WO2024055188A1 - Negative electrode sheet, secondary battery and electric apparatus - Google Patents

Negative electrode sheet, secondary battery and electric apparatus Download PDF

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Publication number
WO2024055188A1
WO2024055188A1 PCT/CN2022/118684 CN2022118684W WO2024055188A1 WO 2024055188 A1 WO2024055188 A1 WO 2024055188A1 CN 2022118684 W CN2022118684 W CN 2022118684W WO 2024055188 A1 WO2024055188 A1 WO 2024055188A1
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active material
material layer
conductive agent
negative electrode
negative
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PCT/CN2022/118684
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French (fr)
Chinese (zh)
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吴凯
温浩楠
严青伟
王家政
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宁德时代新能源科技股份有限公司
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Priority to PCT/CN2022/118684 priority Critical patent/WO2024055188A1/en
Publication of WO2024055188A1 publication Critical patent/WO2024055188A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • This application belongs to the technical field of secondary batteries, and specifically relates to a negative electrode plate, a secondary battery and an electrical device.
  • Secondary batteries are widely used in various consumer electronics and electric vehicles due to their outstanding characteristics such as light weight, no pollution, and no memory effect. As the demand for power batteries gradually expands, customers' demand for power battery energy density is also getting higher and higher.
  • the technical means used to improve the energy density of batteries often lead to the degradation of other aspects of battery performance, such as the dynamic performance, fast charging performance and cycle performance of the battery, while increasing the energy density.
  • this application provides a negative electrode plate, a secondary battery and a power device, aiming to take into account the energy density of the secondary battery while making the secondary battery have better dynamic performance and fast charging. performance and cycle performance.
  • a negative electrode plate including:
  • a negative active material layer is located on at least one surface of the negative current collector.
  • the negative active material layer includes a first conductive agent and a second conductive agent with different aspect ratios.
  • the conduction factor of the negative active material layer is expressed as is i 0 , then the conduction factor of the negative active material layer satisfies: 0.005 ⁇ i 0 ⁇ 3;
  • the conduction factor i 0 (aspect ratio of the first conductive agent*mass proportion of the first conductive agent in the negative active material layer)/total thickness of the negative active material layer+ (Aspect ratio of the second conductive agent*mass proportion of the second conductive agent in the negative active material layer)/total thickness of the negative active material layer;
  • the conduction factor i 0 ((weight of the first conductive agent in the first negative active material layer + second negative active material layer weight of the first conductive agent in the unit area)/total weight of the active material layer on one side of the negative electrode per unit area*aspect ratio of the first conductive agent+(weight of the second conductive agent in the first negative active material layer+second negative active material layer The weight of the second conductive agent)/the total weight of the active material layer on one side of the negative electrode per unit area*the aspect ratio of the second conductive agent)/the total thickness of the active material layer.
  • this application at least includes the following beneficial effects:
  • the negative electrode piece of the present application is provided with a first conductive agent and a second conductive agent with different aspect ratios, and at the same time, a conduction factor i 0 is introduced, and the conduction factor i 0 is related to the aspect ratio of the conductive agent and the conductive agent.
  • the mass proportion in the negative active material layer is positively correlated and negatively correlated with the thickness of the negative active material layer; by adjusting the aspect ratio of the first conductive agent and its mass proportion in the negative active material layer, the second conductive agent
  • the aspect ratio and its mass proportion in the negative active material layer and the thickness of the negative active material layer make the conduction factor i 0 of the negative active material layer satisfy 0.005 ⁇ i 0 ⁇ 3, even in a thicker negative electrode
  • the electron movement path in the negative active material layer can still be increased in the active material layer, so that as much negative active material as possible can participate in the charge and discharge process. In this way, when the above-mentioned negative electrode plate is applied to a secondary battery, it can improve the dynamic performance, fast charging performance and cycle performance of the secondary battery while taking into account the energy density of the secondary battery.
  • the aspect ratio of the first conductive agent is recorded as a, then the aspect ratio of the first conductive agent satisfies: a ⁇ 1000;
  • the first conductive agent includes one or more of carbon black, superconducting acetylene black, Ketjen black and nanosilver wires.
  • the aspect ratio of the second conductive agent is recorded as b, then the aspect ratio of the second conductive agent satisfies: 1000 ⁇ b ⁇ 10000;
  • the second conductive agent includes one or more of single-walled carbon nanotubes and multi-walled carbon nanotubes.
  • the negative active material layer further includes a negative active material, and the negative active material is a carbon-based active material or a mixture of a carbon-based active material and a silicon-based active material.
  • the silicon-based active material includes one or more of silicon, silicon-oxygen materials, and silicon-carbon materials.
  • the negative active material layer is a single layer, and the thickness of the negative active material layer is 46.9-126.6 ⁇ m.
  • the mass proportion of the first conductive agent in the negative active material layer is 0.5 to 5%; the mass proportion of the second conductive agent in the negative active material layer It is 0.005 ⁇ 6%.
  • the mass ratio of the carbon-based active material to the silicon-based active material is (75-100): (0-25).
  • the negative active material layer includes:
  • the first negative active material layer is located on at least one surface of the negative current collector.
  • the conduction factor of the first negative active material layer is denoted as i 1 , then the conduction factor of the first negative active material layer satisfies :0.1 ⁇ i 1 ⁇ 6;
  • the second negative electrode active material layer is located on the surface of the first negative electrode active material layer away from the negative electrode current collector.
  • the conduction factor of the second negative electrode active material layer is denoted as i 2 , then the second negative electrode active material layer
  • the conduction factor of the material layer satisfies: 0 ⁇ i 2 ⁇ 0.75.
  • the mass proportion of the silicon-based material in the first negative active material layer is greater than the mass proportion of the silicon-based material in the second negative active material layer;
  • the mass ratio of the carbon-based material and the silicon-based material in the first negative active material layer is (75-95): (5-25); the carbon-based material and silicon in the second negative active material layer are The mass ratio of the base material is (90 ⁇ 100): (0 ⁇ 10).
  • the mass proportion of the first conductive agent in the first negative active material layer is 0.5-5%; the second conductive agent in the first negative active material layer The mass proportion is 0.05 ⁇ 6%.
  • the mass proportion of the first conductive agent in the second negative active material layer is 0.5 to 5%; the second conductive agent in the second negative active material layer The mass proportion is 0 ⁇ 3%.
  • the sum of the thicknesses of the first negative active material layer and the second negative active material layer is 46.9-126.6 ⁇ m;
  • the thickness ratio of the first negative active material layer and the second negative active material layer is (0.25 ⁇ 0.67):1.
  • the negative electrode sheet has a sheet density of 8.4 mg/cm 2 to 13 mg/cm 2 .
  • a second aspect of the present application provides a secondary battery, which includes the negative electrode plate of the first aspect of the present application.
  • a third aspect of the present application provides an electrical device, which includes the secondary battery of the second aspect of the present application.
  • FIG. 1 is a schematic diagram of an embodiment of a negative electrode sheet.
  • FIG. 2 is a schematic diagram of an embodiment of a negative electrode plate.
  • FIG. 3 is a schematic diagram of an embodiment of a secondary battery.
  • FIG. 4 is an exploded view of FIG. 3 .
  • Figure 5 is a schematic diagram of an embodiment of a battery pack.
  • FIG. 6 is a schematic diagram of an electrical device using a secondary battery as a power source according to an embodiment.
  • any lower limit can be combined with any upper limit to form an unexpressed range; and any lower limit can be combined with other lower limits to form an unexpressed range, and likewise any upper limit can be combined with any other upper limit to form an unexpressed range.
  • each individually disclosed point or single value may itself serve as a lower or upper limit in combination with any other point or single value or with other lower or upper limits to form a range not expressly recited.
  • Ranges disclosed herein are defined in terms of lower and upper limits. A given range is defined by selecting a lower limit and an upper limit that define the boundaries of the particular range. Ranges defined in this manner may be inclusive or exclusive of the endpoints, and may be arbitrarily combined, that is, any lower limit may be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, understand that ranges of 60-110 and 80-120 are also expected. Furthermore, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2- 3, 2-4 and 2-5.
  • the numerical range “a-b” represents an abbreviated representation of any combination of real numbers between a and b, where a and b are both real numbers.
  • the numerical range “0-5" means that all real numbers between "0-5" have been listed in this article, and "0-5" is just an abbreviation of these numerical combinations.
  • a certain parameter is an integer ⁇ 2
  • the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially.
  • step (c) means that step (c) may be added to the method in any order.
  • the method may include steps (a), (b) and (c). , may also include steps (a), (c) and (b), may also include steps (c), (a) and (b), etc.
  • the negative electrode sheet provided by this application includes: a negative electrode current collector; a negative electrode active material layer located on at least one surface of the negative electrode current collector.
  • the negative electrode active material layer includes a first conductive agent and a second conductive agent with different aspect ratios.
  • the negative electrode The conduction factor of the active material layer is recorded as i 0 , then the conduction factor of the negative active material layer satisfies: 0.005 ⁇ i 0 ⁇ 3;
  • the conduction factor i 0 (aspect ratio of the first conductive agent*mass proportion of the first conductive agent in the negative active material layer)/total thickness of the negative active material layer+(th The aspect ratio of the second conductive agent*the mass proportion of the second conductive agent in the negative active material layer)/the total thickness of the negative active material layer;
  • the conduction factor i 0 ((weight of the first conductive agent in the first negative active material layer + the weight of the first conductive agent in the second negative active material layer The weight of a conductive agent) / the total weight of the active material layer on one side of the negative electrode per unit area * the aspect ratio of the first conductive agent + (the weight of the second conductive agent in the first negative active material layer + the second conductive agent in the second negative active material layer The weight of the second conductive agent)/the total weight of the active material layer on one side of the negative electrode per unit area*the aspect ratio of the second conductive agent))/the total thickness of the active material layer.
  • the negative electrode piece of the present application is provided with a first conductive agent and a second conductive agent with different aspect ratios, and at the same time, a conduction factor i 0 is introduced, and the conduction factor i 0 is related to the length of the conductive agent.
  • the diameter ratio is positively correlated with the mass proportion of the conductive agent in the negative active material layer, and negatively correlated with the thickness of the negative active material layer; by adjusting the aspect ratio of the first conductive agent and its mass proportion in the negative active material layer ratio, the aspect ratio of the second conductive agent and its mass proportion in the negative active material layer and the thickness of the negative active material layer, so that the conduction factor i 0 of the negative active material layer satisfies 0.005 ⁇ i 0 ⁇ 3, Even in a thick negative active material layer, the electron movement path in the negative active material layer can still be increased, so that as much negative active material as possible can participate in the charge and discharge process. In this way, when the above-mentioned negative electrode plate is applied to a secondary battery, it can improve the dynamic performance, fast charging performance and cycle performance of the secondary battery while taking into account the energy density of the secondary battery.
  • the greater the aspect ratio of the conductive agent the more elongated and linear its shape will be.
  • its dosage can be appropriately reduced.
  • the smaller the aspect ratio of the conductive agent the shape tends to be short tube or point-like.
  • its dosage can be appropriately increased.
  • the conduction factor is positively correlated with the aspect ratio of the conductive agent and the mass proportion of the conductive agent in the negative active material layer, and is negatively correlated with the thickness of the negative active material layer.
  • the conduction factor (the length of the conductive agent Diameter ratio*the mass proportion of the conductive agent in the negative active material layer)/the total thickness of the negative active material layer ( ⁇ m).
  • the conduction factor i 0 of the negative active material layer (aspect ratio of the first conductive agent * mass proportion of the first conductive agent in the negative active material layer)/ The total thickness of the negative active material layer ( ⁇ m) + (the aspect ratio of the second conductive agent * the mass proportion of the second conductive agent in the negative active material layer) / the total thickness of the negative active material layer ( ⁇ m).
  • the conduction factor i 0 of the negative active material layer is measured using the following method: 1. Before embedding lithium, perform cross-sectional CP characterization of the negative electrode piece and measure the thickness of the negative active material layer; 2. , before embedding lithium, weigh out the weight of the negative electrode piece per unit area and the weight of the negative electrode current collector per unit area, based on the formula: (weight of the negative electrode piece per unit area - weight of the negative electrode current collector per unit area)/2, calculation unit The weight of the active material layer on one side of the negative electrode per area; 3.
  • the conduction factor i 0 of the negative active material layer ((the first conductive agent in the first negative active material layer Weight + weight of the first conductive agent in the second negative electrode active material layer) / total weight of the active material layer on one side of the negative electrode per unit area * aspect ratio of the first conductive agent + ( second conductive agent in the first negative electrode active material layer Weight + weight of the second conductive agent in the second negative active material layer)/total weight of the active material layer on one side of the negative electrode per unit area*aspect ratio of the second conductive agent))/total thickness of the active material layer.
  • the conduction factor i 0 of the total negative active material layer is measured using the following method: 1. Before lithium insertion, the negative electrode piece Perform cross-sectional CP characterization and measure the thickness of the total negative active material layer; 2. Before embedding lithium, weigh the weight of the negative electrode piece per unit area and the weight of the negative electrode current collector per unit area, based on the formula: (negative electrode piece per unit area weight - the weight of the negative electrode current collector per unit area)/2, calculate the total weight of the active material layer on one side of the negative electrode per unit area; 3.
  • the first negative active material layer on the surface of the current collector; 4. Soak the second negative active material layer in pure water, rinse it several times until the binder is washed away, and dry to obtain the silicon in the second negative active material layer.
  • the weight of the agent and the weight of the second conductive agent 5.
  • the first conductive agent and the second conductive agent in the first negative active material layer are respectively Carry out SEM scanning and measure the aspect ratio of the first conductive agent and the second conductive agent in the first negative active material layer; 8. Substitute each measurement value obtained above into the formula: ((The first conductive agent in the first negative active material layer Agent weight + weight of the first conductive agent in the second negative electrode active material layer) / total weight of the active material layer on one side of the negative electrode per unit area * aspect ratio of the first conductive agent + ( second conductive agent in the first negative electrode active material layer Agent weight + weight of the second conductive agent in the second negative active material layer)/total weight of the active material layer on one side of the negative electrode per unit area*aspect ratio of the second conductive agent))/total thickness of the active material layer, calculate the total The conduction factor i 0 of the negative active material layer.
  • the inventor found that when the negative electrode plate of the present application meets the above design conditions and optionally meets one or more of the following conditions, the kinetics of the secondary battery can be further improved. performance, fast charging performance and cycle performance.
  • the aspect ratio of the first conductive agent is recorded as a, then the aspect ratio of the first conductive agent satisfies: a ⁇ 1000; for example, the aspect ratio of the first conductive agent can satisfy 1.01 ⁇ a ⁇ 800, 1.01 ⁇ a ⁇ 200, 100 ⁇ a ⁇ 500 or 200 ⁇ a ⁇ 800, etc.
  • the shape of the first conductive agent tends to be short tube-like or dot-like. Further, the aspect ratio of the first conductive agent satisfies: 1.01 ⁇ a ⁇ 200.
  • the first conductive agent includes one or more of carbon black, superconducting acetylene black, Ketjen black and nanosilver wires.
  • the aspect ratio of the second conductive agent is recorded as b, then the aspect ratio of the second conductive agent satisfies: 1000 ⁇ b ⁇ 10000; for example, the aspect ratio of the second conductive agent can satisfy 1000 ⁇ b ⁇ 5000, 2000 ⁇ b ⁇ 7000 or 5000 ⁇ b ⁇ 10000, etc.
  • the shape of the second conductive agent tends to be elongated and linear.
  • the linear second conductive agent can be attached to the surface of the silicon-based active material. In the case of a silicon-based active material While conducting electrons, it restrains the expansion of silicon-based materials during the lithium insertion process. Further, the aspect ratio of the second conductive agent satisfies: 5000 ⁇ b ⁇ 10000.
  • the second conductive agent includes one or more of single-walled carbon nanotubes and multi-walled carbon nanotubes.
  • the negative active material layer further includes a negative active material, and the negative active material is a carbon-based active material or a mixture of a carbon-based active material and a silicon-based active material.
  • the negative active material may be entirely carbon-based active material, or may be partly carbon-based active material and partly silicon-based active material.
  • the negative active material is partly carbon-based active material and partly silicon-based active material.
  • Silicon-based active materials have high capacity but their volume expansion rate is too large during the lithium intercalation process. Although carbon-based active materials have a smaller volume expansion rate during the lithium intercalation process, their capacity is lower than that of silicon-based active materials.
  • the carbon-based active material includes one or more of artificial graphite and natural graphite.
  • the silicon-based active material includes one or more of silicon, silicon-oxygen materials, and silicon-carbon materials.
  • FIG. 1 is a schematic diagram of an embodiment of a negative electrode plate.
  • the negative active material layer is a single layer, and the thickness of the negative active material layer is 46.9-126.6 ⁇ m; for example, it can be 46.9-51.5 ⁇ m, 52.5-75 ⁇ m, 54-68 ⁇ m, or 75 ⁇ m. ⁇ 126.6 ⁇ m etc.
  • Technicians have found through research that when the thickness of the negative active material layer is within the above range, the secondary battery can have excellent dynamic performance, fast charging performance and cycle performance while taking into account the energy density of the secondary battery.
  • the thickness of the above-mentioned negative electrode active material layer is measured using the following method: cross-sectional CP characterization of the negative electrode piece is performed, and the thickness of the negative electrode active material layer is measured.
  • the mass proportion of the first conductive agent in the negative active material layer is 0.5-5%; for example, it can be 0.5-1%, 1-5%, or 2-4%.
  • the mass proportion of the second conductive agent in the negative active material layer is 0.005-6%; for example, it can be 0.005-1.55%, 0.87-3.1%, 0.15-5% or 1-6%.
  • the mass ratio of the carbon-based active material to the silicon-based active material is (75 ⁇ 100): (0 ⁇ 25); for example, it can be (75 ⁇ 85): (15 ⁇ 25) or ( 85 ⁇ 100):(0 ⁇ 15) etc.
  • Embodiments of the present application also provide a method for preparing a negative electrode sheet, including: preparing a negative electrode slurry, and coating the negative electrode slurry on at least one surface of the negative electrode current collector to form a negative electrode active material layer.
  • FIG. 2 is a schematic diagram of an embodiment of a negative electrode plate.
  • the negative active material layer includes: a first negative active material layer located on at least one surface of the negative current collector, and the conduction factor of the first negative active material layer is denoted as i 1 , Then the conduction factor of the first negative active material layer satisfies: 0.1 ⁇ i 1 ⁇ 6; the second negative active material layer is located on the surface of the first negative active material layer away from the negative current collector, and the conduction factor of the second negative active material layer is The pass factor is recorded as i 2 , then the conduction factor of the second negative electrode active material layer satisfies: 0 ⁇ i 2 ⁇ 0.75.
  • the conduction factor i 1 of the first negative electrode active material layer and the conduction factor i 2 of the second negative electrode active material layer independently satisfy the above range, the first negative electrode active material layer and the conduction factor i 2 can also be made.
  • the conduction factor i 0 of the total negative active material layer composed of the second negative active material layer satisfies: 0.005 ⁇ i 0 ⁇ 3.
  • the conduction factor i 1 (aspect ratio of the first conductive agent * mass proportion of the first conductive agent in the first negative electrode active material layer) / total mass of the first negative electrode active material layer Thickness ( ⁇ m) + (aspect ratio of the second conductive agent * mass proportion of the second conductive agent in the first negative active material layer)/total thickness of the first negative active material layer ( ⁇ m).
  • the conduction factor i 1 is measured using the following method: 1. Before lithium embedding, perform cross-sectional CP characterization of the negative electrode piece and measure the thickness of the first negative electrode active material layer; 2. Before lithium embedding, take out the negative electrode piece per unit area Separate the upper and lower layers to obtain the first negative electrode active material layer located on the surface of the negative electrode current collector; 3. Weigh the weight of the negative electrode sheet per unit area after removing the second negative electrode active material layer, and the weight of the negative electrode current collector per unit area, based on Formula: (weight of the negative electrode sheet per unit area after removing the second negative electrode active material layer - weight of the negative electrode current collector per unit area)/2, calculate the weight of the first negative electrode active material layer on one side of the negative electrode per unit area; 4.
  • the current collector and the first negative active material layer located on its surface are soaked in pure water. All the first negative active material layers are washed and mixed in pure water. Filter and rinse multiple times until the binder is washed and dried.
  • the mixture of silicon-based material, carbon-based material, first conductive agent and second conductive agent in the first negative electrode active material layer is obtained by drying; and the mixture is subjected to physical classification treatment to obtain the silicon-based material in the first negative electrode active material layer. weight, the weight of the carbon-based material, the weight of the first conductive agent and the weight of the second conductive agent; 5.
  • the conduction factor i 2 (aspect ratio of the first conductive agent * mass proportion of the first conductive agent in the first negative electrode active material layer) / total mass of the first negative electrode active material layer Thickness ( ⁇ m) + (aspect ratio of the second conductive agent * mass proportion of the second conductive agent in the first negative active material layer)/total thickness of the first negative active material layer ( ⁇ m).
  • the conduction factor i 2 is measured using the following method: 1. Before lithium embedding, perform cross-sectional CP characterization of the negative electrode piece and measure the thickness of the second negative electrode active material layer; 2. Before lithium embedding, take out the negative electrode piece per unit area Separate the upper and lower layers to obtain a single layer of the second negative active material layer, and weigh its weight to obtain the weight of the second negative active material layer on one side of the negative electrode per unit area; 3.
  • the negative electrode per unit area The weight of the second negative electrode active material layer on one side is used to calculate the mass proportion of the first conductive agent in the second negative electrode active material layer; based on the weight of the second conductive agent in the second negative electrode active material layer and the second negative electrode on one side of the negative electrode per unit area According to the weight of the active material layer, calculate the mass proportion of the second conductive agent in the second negative electrode active material layer; 6.
  • the mass proportion of the silicon-based material in the first negative active material layer is greater than the mass proportion of the silicon-based material in the second negative active material layer.
  • the silicon-based material in the first negative active material layer will not produce an excessive expansion effect.
  • the electrochemical performance of the secondary battery is more affected by the second negative active material layer.
  • Providing more carbon-based materials in the second negative active material layer can improve the cycle and storage performance of the secondary battery.
  • the mass proportion of silicon-based materials in the first negative active material layer is relatively large.
  • the conduction factor i 1 of the first negative active material layer is in the above range, the mass proportion of the linear conductive agent in it is relatively large. , which can conduct electrons for the silicon-based active material while reducing the expansion of the silicon-based material during the lithium insertion process; the carbon-based material in the second negative electrode active material layer accounts for a large proportion of the mass, and the conduction of the second negative electrode active material layer
  • the pass factor i 2 is within the above range, the secondary battery can have better electrochemical performance.
  • the mass ratio of the carbon-based material and the silicon-based material in the first negative active material layer is (75 ⁇ 95): (5 ⁇ 25); for example, it can be (75 ⁇ 85): (15 ⁇ 25) or (85 ⁇ 95): (5 ⁇ 15) etc.
  • the mass ratio of the carbon-based material and the silicon-based material in the second negative electrode active material layer is (90 ⁇ 100): (0 ⁇ 10); for example, it can be (90 ⁇ 95): (5 ⁇ 10), (95 ⁇ 100): (0 ⁇ 5) or (90 ⁇ 98): (2 ⁇ 10) etc.
  • the mass proportion of the first conductive agent in the first negative active material layer is 0.5-5%; for example, it can be 0.5-1.2%, 1.5-3%, or 1-5%.
  • the mass proportion of the second conductive agent in the first negative active material layer is 0.05-6%; for example, it can be 0.05-1%, 0.3-2.1%, or 2.1-6%.
  • the mass proportion of the first conductive agent in the second negative electrode active material layer is 0.5-5%; for example, it can be 0.5-1%, 1-4%, or 2-5%.
  • the mass proportion of the second conductive agent in the second negative electrode active material layer is 0 to 3%; for example, it can be 0 to 0.5%, 0.3 to 1%, or 1 to 3%.
  • the sum of the thicknesses of the first negative active material layer and the second negative active material layer is 46.9-126.6 ⁇ m.
  • Technicians have found through research that when the sum of the thicknesses of the first negative electrode active material layer and the second negative electrode active material layer is within the above range, the secondary battery can have excellent kinetics while taking into account the energy density of the secondary battery. performance, fast charging performance and cycle performance.
  • the thickness ratio of the first negative active material layer and the second negative active material layer is (0.25 ⁇ 0.67):1.
  • the thickness of the second negative electrode active material layer is beneficial to form a gradient pore distribution between the second negative electrode active material layer and the first negative electrode active material layer, so that the active ions released from the positive electrode are dispersed in the negative electrode membrane.
  • the liquid phase conduction resistance on the surface of the layer is reduced, which can avoid the accumulation of active ions on the surface of the negative electrode film layer and cause lithium precipitation.
  • the uniform diffusion of active ions in the negative electrode film layer is conducive to reducing polarization and further improving the power of the secondary battery. chemical performance and cycle performance.
  • the ratio of the thickness of the first negative electrode active material layer and the second negative electrode active material layer mentioned above is measured using the following method: before lithium embedding, perform cross-sectional CP characterization of the negative electrode piece, and measure the thickness of the first negative electrode active material layer respectively. thickness and the thickness of the second negative electrode active material layer, and then calculate the ratio of the thickness of the first negative electrode active material layer to the thickness of the second negative electrode active material layer.
  • the negative electrode piece has an area density of 8.4 mg/cm 2 to 13 mg/cm 2 .
  • Technicians have found through research that when the density of the negative electrode piece is within the above range, the energy density and fast charging performance of the negative electrode piece can be further improved.
  • the surface density of the above-mentioned negative electrode piece is measured using the following method: Use a punching die to punch out a 1cm 2 negative electrode piece, and then weigh it to obtain the total weight M0 of the 1cm 2 piece; punch out a 1cm 2 negative electrode Clean the active material layer of the electrode piece with pure water, and then weigh it to obtain the weight M1 of the negative electrode current collector. Then calculate the electrode piece surface density of the negative electrode piece based on the formula (M0-M1)/2.
  • Embodiments of the present application also provide a method for preparing a negative electrode sheet, including the following steps:
  • the negative electrode current collector can use conventional metal foil or composite current collector.
  • the metal foil may be copper foil.
  • the composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base material.
  • the composite current collector can be formed by forming metal materials (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as polypropylene (PP), polyterephthalate It is formed on substrates such as ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the negative active material layer usually also includes conductive agents, binders and other optional auxiliaries.
  • the conductive agent may be one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • the weight ratio of the conductive agent in the negative electrode film layer is 0 to 20% by weight, based on the total weight of the negative electrode film layer.
  • the binder may be selected from styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), At least one of polymethacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).
  • SBR styrene-butadiene rubber
  • PAA polyacrylic acid
  • PAAS sodium polyacrylate
  • PAM polyacrylamide
  • PVA polyvinyl alcohol
  • SA sodium alginate
  • PMAA polymethacrylic acid
  • CMCS carboxymethyl chitosan
  • other optional additives may be PTC thermistor materials, etc.
  • the weight ratio of the other additives in the negative electrode film layer is 0 to 15% by weight, based on the total weight of the negative electrode film layer.
  • Secondary batteries refer to batteries that can be recharged to activate active materials and continue to be used after the battery is discharged.
  • a secondary battery includes a positive electrode sheet, the negative electrode sheet provided above in this application, a separator and an electrolyte.
  • active ions are inserted and detached back and forth between the positive and negative electrodes.
  • the isolation film is arranged between the positive electrode piece and the negative electrode piece to play the role of isolation.
  • the electrolyte plays a role in conducting ions between the positive and negative electrodes.
  • a positive electrode sheet usually includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector.
  • the positive electrode film layer includes a positive electrode active material.
  • the positive electrode current collector has two surfaces facing each other in its own thickness direction, and the positive electrode film layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.
  • the positive electrode current collector may use a metal foil or a composite current collector.
  • the metal foil aluminum foil can be used.
  • the composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer.
  • the composite current collector can be formed by forming metal materials (aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver and silver alloys, etc.) on polymer material substrates (such as polypropylene (PP), polyterephthalate It is formed on substrates such as ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the cathode active material may be a cathode active material known in the art for lithium ion batteries.
  • the cathode active material may include at least one of the following materials: an olivine-structured lithium-containing phosphate, a lithium transition metal oxide, and their respective modified compounds.
  • the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials of batteries can also be used. Only one type of these positive electrode active materials may be used alone, or two or more types may be used in combination.
  • lithium transition metal oxides may include, but are not limited to, lithium cobalt oxides (such as LiCoO 2 ), lithium nickel oxides (such as LiNiO 2 ), lithium manganese oxides (such as LiMnO 2 , LiMn 2 O 4 ), lithium Nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1/3 Co 1/3 Mn 1/3 O 2 (also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O 2 (can also be abbreviated to NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O 2 (can also be abbreviated to NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O 2 (can also be abbreviated to NCM 622 ), LiNi At least one of 0.8 Co 0.1 Mn 0.1 O 2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as Li Li
  • the olivine structure contains Examples of lithium phosphates may include, but are not limited to, lithium iron phosphate (such as LiFePO 4 (also referred to as LFP)), composites of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO 4 ), lithium manganese phosphate and carbon. At least one of composite materials, lithium iron manganese phosphate, and composite materials of lithium iron manganese phosphate and carbon.
  • the weight ratio of the positive electrode active material in the positive electrode film layer is 80 to 100% by weight, based on the total weight of the positive electrode film layer count.
  • the cathode active material may be a cathode active material known in the art for sodium-ion batteries.
  • the cathode active material may be a cathode active material known in the art for sodium-ion batteries.
  • only one type of positive electrode active material may be used alone, or two or more types may be combined.
  • the positive active material can be selected from sodium iron composite oxide (NaFeO 2 ), sodium cobalt composite oxide (NaCoO 2 ), sodium chromium composite oxide (NaCrO 2 ), sodium manganese composite oxide (NaMnO 2 ), sodium nickel Composite oxide (NaNiO 2 ), sodium nickel titanium composite oxide (NaNi 1/2 Ti 1/2 O 2 ), sodium nickel manganese composite oxide (NaNi 1/2 Mn 1/2 O 2 ), sodium iron manganese composite Oxide (Na 2/3 Fe 1/3 Mn 2/3 O 2 ), sodium nickel cobalt manganese composite oxide (NaNi 1/3 Co 1/3 Mn 1/3 O 2 ), sodium iron phosphate compound (NaFePO 4 ), sodium manganese phosphate compound (NaMn P O 4 ), sodium cobalt phosphate compound (NaCoPO 4 ), Prussian blue materials, polyanionic materials (phosphates, fluorophosphates, pyrophosphates, sulfates), etc.,
  • the positive electrode film layer also optionally includes binders, conductive agents and other optional auxiliaries.
  • the binder may include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene At least one of ethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer and fluorine-containing acrylate resin.
  • the weight ratio of the binder in the positive electrode film layer is 0 to 20% by weight, based on the total weight of the positive electrode film layer.
  • the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • the weight ratio of the conductive agent in the positive electrode film layer is 0 to 20% by weight, based on the total weight of the positive electrode film layer.
  • the positive electrode sheet can be prepared in the following manner: the above-mentioned components for preparing the positive electrode sheet, such as the positive active material, the conductive agent, the binder and any other components are dispersed in a solvent (such as N-methyl pyrrolidone) to form a positive electrode slurry, wherein the solid content of the positive electrode slurry is 40 to 80 wt%, and the viscosity at room temperature is adjusted to 5000 to 25000 mPa ⁇ s; the positive electrode slurry is coated on the positive electrode current collector and dried , cold pressing and other processes, the positive electrode piece can be obtained; the unit area density of the positive electrode powder coating is 150 ⁇ 350 mg/m 2 , and the compacted density of the positive electrode piece is 3.0 ⁇ 3.6g/cm 3 , optionally 3.3 ⁇ 3.5 g/cm 3 .
  • the calculation formula of the compacted density is
  • Compaction density coating surface density / (thickness of electrode piece after extrusion - thickness of current collector).
  • the secondary battery further includes a separator film.
  • a separator film There is no particular restriction on the type of isolation membrane in this application. Any well-known porous structure isolation membrane with good chemical stability and mechanical stability can be used.
  • the material of the isolation membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride.
  • the isolation film can be a single-layer film or a multi-layer composite film, with no special restrictions. When the isolation film is a multi-layer composite film, the materials of each layer can be the same or different, and there is no particular limitation.
  • the thickness of the isolation film is 6-40 ⁇ m, optionally 12-20 ⁇ m.
  • the positive electrode piece, the negative electrode piece and the separator film can be made into an electrode assembly through a winding process or a lamination process.
  • the secondary battery may include an electrolyte that serves to conduct ions between a positive electrode and a negative electrode.
  • the electrolyte solution may include electrolyte salts and solvents.
  • the electrolyte salt may be selected from lithium hexafluorophosphate (LiPF 6 ), lithium tetrafluoroborate (LiBF 4 ), lithium perchlorate (LiClO 4 ), lithium hexafluoroarsenate (LiAsF 6 ), lithium bisfluorosulfonyl imide ( LiFSI), lithium bistrifluoromethanesulfonimide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluoromethanesulfonate borate (LiDFOB), lithium dioxalatoborate (LiBOB), lithium difluorophosphate (LiPO 2 F 2 ), one or more of lithium difluorodioxalate phosphate (LiDFOP) and lithium tetrafluorooxalate phosphate (LiTFOP).
  • the concentration of the electrolyte salt is usually 0.5 to 5 mol/L.
  • the solvent may be selected from ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), carbonic acid Dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), One or more of ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS) and diethyl sulf
  • additives are also included in the electrolyte.
  • additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain properties of the battery, such as additives that improve the overcharge performance of the battery, additives that improve the high-temperature performance of the battery, and additives that improve the low-temperature performance of the battery. Additives etc.
  • the secondary battery of the present application is a lithium-ion secondary battery.
  • the secondary battery can be prepared according to conventional methods in the art, for example, the positive electrode sheet, the separator film, and the negative electrode sheet are wound (or stacked) in order, so that the separator film is between the positive electrode sheet and the negative electrode sheet for isolation. function to obtain the battery core, place the battery core in the outer package, inject the electrolyte and seal it to obtain a secondary battery.
  • FIG. 3 shows an example of a square-structured secondary battery 4 .
  • the secondary battery may include an outer packaging.
  • the outer packaging can be used to package the above-mentioned electrode assembly and electrolyte.
  • the outer packaging of the secondary battery may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc.
  • the outer packaging of the secondary battery may also be a soft bag, such as a bag-type soft bag.
  • the material of the soft bag may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, polybutylene succinate, and the like.
  • the outer package may include a housing 41 and a cover 43 .
  • the housing 41 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and the side plates enclose a receiving cavity.
  • the housing 41 has an opening communicating with the accommodation cavity, and the cover plate 43 can cover the opening to close the accommodation cavity.
  • the positive electrode piece, the negative electrode piece and the isolation film can be formed into the electrode assembly 42 through a winding process or a lamination process.
  • the electrode assembly 52 is packaged in the containing cavity.
  • the electrolyte soaks into the electrode assembly 42 .
  • the number of electrode assemblies 42 contained in the secondary battery 4 can be one or more, and can be adjusted according to requirements.
  • the above-mentioned secondary batteries can also be assembled into a battery pack, and the number of secondary batteries contained in the battery pack can be adjusted according to the application and capacity of the battery pack.
  • FIG. 5 is a battery pack 1 as an example.
  • the battery pack 1 may include a battery box and a plurality of secondary batteries 4 provided in the battery box.
  • the battery box includes an upper box 2 and a lower box 3 .
  • the upper box 2 can be covered with the lower box 3 and form a closed space for accommodating the secondary battery 4 .
  • the plurality of secondary batteries 4 can be arranged in the battery box in any manner.
  • the present application also provides an electrical device, which includes at least one of the secondary battery or battery pack.
  • the secondary battery or battery pack may be used as a power source for the device or as an energy storage unit for the device.
  • the device may be, but is not limited to, a mobile device (such as a mobile phone, a laptop, etc.), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, or an electric golf ball). vehicles, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.
  • the device can select secondary batteries or battery packs according to its usage requirements.
  • FIG. 6 shows an electrical device 5 as an example.
  • the electric device 5 is a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, or the like.
  • a battery pack can be used.
  • the device may be a mobile phone, a tablet, a laptop, etc.
  • the device is usually required to be thin and light, and a secondary battery can be used as a power source.
  • the electrode pieces After drying, the electrode pieces are cold pressed and cut into negative electrode pieces with a length of 735mm and a film width of 93mm.
  • the area density of the electrode pieces is 12 mg/cm. 2
  • the compacted density is 1.6g/cm 3
  • the total thickness of both sides of the pole piece is 158 ⁇ m.
  • the preparation method of the negative electrode piece in Examples 2-8 is basically similar to the preparation method of the negative electrode piece in Example 1.
  • the main difference lies in: the type and/or amount of the first conductive agent used when preparing the negative electrode piece, and the amount of the first conductive agent.
  • At least one of the type and/or amount of the conductive agent, the thickness of the negative active material layer, and the mass ratio of the carbon-based material and the silicon-based material in the negative active material layer is different. See Table 1 for details.
  • the preparation method of the negative electrode piece in Examples 2-8 and the preparation method of the negative electrode piece in Example 1 also include the following differences: the mass ratio of the negative active material, conductive agent and other auxiliaries and the area density of the electrode piece when preparing the negative electrode piece At least one of them is different.
  • Example 2 the negative active material, single-walled carbon nanotubes (as the second conductive agent), the conductive agent acetylene black (as the first conductive agent), the thickener sodium carboxymethyl cellulose (CMC), and the viscose
  • the binder styrene-butadiene rubber (SBR) is mixed according to the mass ratio of 95.795:0.005:1:1.2:2; the polar sheet density is 8.18 mg/cm 2 .
  • Example 3 the negative electrode active material, single-walled carbon nanotubes (as the second conductive agent), the conductive agent acetylene black (as the first conductive agent), the thickener sodium carboxymethyl cellulose (CMC), and the binder D Styrene rubber (SBR) is mixed according to the mass ratio of 94.75:1.05:1:1.2:2; the polar sheet density is 8.26 mg/cm 2 .
  • Example 4 the negative electrode active material, single-walled carbon nanotubes (as the second conductive agent), conductive agent acetylene black (as the first conductive agent), thickener sodium carboxymethyl cellulose (CMC), and binder styrene butadiene rubber (SBR) were mixed at a mass ratio of 92.56:3.24:1:1.2:2; the electrode sheet surface density was 8.44 mg/cm 2 .
  • Example 5 the negative electrode active material, single-walled carbon nanotubes (as the second conductive agent), nanosilver wires (as the first conductive agent), thickener sodium carboxymethyl cellulose (CMC), and binder butyl styrene
  • SBR The rubber
  • SBR is mixed according to the mass ratio of 94.76:1.04:1:1.2:2; the polar sheet density is 8.44mg/cm 2 .
  • Example 6 the negative active material, single-walled carbon nanotubes (as the second conductive agent), nanosilver wires (as the first conductive agent), thickener sodium carboxymethyl cellulose (CMC), and binder butyl styrene
  • SBR The rubber
  • SBR is mixed according to the mass ratio of 94.88:0.92:1:1.2:2; the polar sheet density is 8.44mg/cm 2 .
  • Example 7 the negative electrode active material, single-walled carbon nanotubes (as the second conductive agent), the conductive agent acetylene black (as the first conductive agent), the thickener sodium carboxymethyl cellulose (CMC), and the binder D Styrene rubber (SBR) is mixed according to the mass ratio of 90.3:5.5:1:1.2:2; the polar sheet density is 8.63 mg/cm 2 .
  • Example 8 the negative active material, single-walled carbon nanotubes (as the second conductive agent), the conductive agent acetylene black (as the first conductive agent), the thickener sodium carboxymethyl cellulose (CMC), and the binder D Styrene rubber (SBR) is mixed according to the mass ratio of 95.275:0.525:1:1.2:2; the pole sheet density is 8.28 mg/cm 2 .
  • Preparation of the first negative electrode slurry combine the negative active material, single-walled carbon nanotubes (as the second conductive agent), the conductive agent acetylene black (as the first conductive agent), and the thickener sodium carboxymethylcellulose (CMC) , the binder styrene-butadiene rubber (SBR) is mixed according to the mass ratio of 95.745:0.055:1:1.2:2, add the solvent deionized water, and stir under the action of a vacuum mixer until the system is uniform;
  • SBR styrene-butadiene rubber
  • Preparation of the second negative electrode slurry combine the negative active material, single-walled carbon nanotubes (as the second conductive agent), the conductive agent acetylene black (as the first conductive agent), and the thickener sodium carboxymethyl cellulose (CMC) , the binder styrene-butadiene rubber (SBR) is mixed according to the mass ratio of 95.5:0.3:1:1.2:2, add the solvent deionized water, and stir under the action of a vacuum mixer until the system is uniform;
  • SBR styrene-butadiene rubber
  • the first negative electrode slurry and the second negative electrode slurry are evenly coated on both surfaces of the negative electrode current collector copper foil with a thickness of 8 ⁇ m at 4.22 mg/cm 2 and 6.62 mg/cm 2 in sequence, and dried at 110°C for 20 minutes. After drying, the pole pieces were cold-pressed and cut to obtain negative electrode pole pieces with a length of 735mm and a film width of 93mm.
  • the surface density of the pole piece was 10.84mg/cm 2 and the compacted density was 1.6g/cm 3 .
  • the total thickness of both sides of the pole piece was 144 ⁇ m.
  • the preparation method of the negative electrode piece in Examples 10-11 is basically similar to the preparation method of the negative electrode piece in Example 9.
  • the main difference lies in: when preparing the negative electrode piece, the first conductive agent used in the first negative active material layer is The type and/or amount, the type and/or amount of the second conductive agent in the first negative active material layer, the thickness of the first negative active material layer, and the mass ratio of the carbon-based material and the silicon-based material in the first negative active material layer At least one of them is different, see Table 2 for details.
  • the preparation method of the negative electrode sheet in Examples 10-11 and the preparation method of the negative electrode sheet in Example 9 also include the following differences: when preparing the negative electrode sheet, the negative active material, conductive agent and other auxiliary agents in the first negative active material layer At least one of the mass ratio and the polar area density is different.
  • the negative electrode active material single-walled carbon nanotubes (as the second conductive agent), the conductive agent acetylene black (as the first conductive agent), and the thickener carboxymethyl Sodium cellulose (CMC) and binder styrene-butadiene rubber (SBR) are mixed at a mass ratio of 94.8:1:1:1.2:2.
  • CMC carboxymethyl Sodium cellulose
  • SBR binder styrene-butadiene rubber
  • the first negative electrode slurry and the second negative electrode slurry are evenly coated on both surfaces of the negative electrode current collector copper foil with a thickness of 8 ⁇ m at 3.25 mg/cm 2 and 6.62 mg/cm 2 in sequence, and dried at 110°C for 20 minutes. After drying, the pole pieces are cold-pressed and cut to obtain negative electrode pole pieces with a length of 735mm and a film width of 93mm.
  • the surface density of the pole piece is 9.87mg/cm 2
  • the compacted density is 1.6g/cm 3
  • the total thickness of both sides of the pole piece is 133 ⁇ m.
  • the negative electrode active material, single-walled carbon nanotubes (as the second conductive agent), the conductive agent acetylene black (as the first conductive agent), and the thickener sodium carboxymethylcellulose (CMC) and binder styrene-butadiene rubber (SBR) are mixed at a mass ratio of 94.384:1.416:1:1.2:2.
  • the first negative electrode slurry and the second negative electrode slurry are evenly coated on both surfaces of the negative electrode current collector copper foil with a thickness of 8 ⁇ m at 2.79 mg/cm 2 and 6.62 mg/cm 2 in sequence, and dried at 110°C for 20 minutes. After drying, the pole pieces are cold-pressed and cut to obtain negative electrode pole pieces with a length of 735mm and a film width of 93mm.
  • the surface density of the pole piece is 9.52mg/cm 2
  • the compacted density is 1.6g/cm 3
  • the total thickness of both sides of the pole piece is 126 ⁇ m.
  • the preparation method of the negative electrode piece in Examples 12-14 is basically similar to the preparation method of the negative electrode piece in Example 10.
  • the main difference lies in: when preparing the negative electrode piece, the amount of the first conductive agent used in the second negative electrode active material layer is The type and/or amount, the type and/or amount of the second conductive agent in the second negative electrode active material layer, the thickness of the second negative electrode active material layer, and the mass ratio of the carbon-based material and the silicon-based material in the second negative electrode active material layer At least one of them is different, see Table 2 for details.
  • the preparation method of the negative electrode sheet in Examples 12-14 and the preparation method of the negative electrode sheet in Example 10 also include the following differences: when preparing the negative electrode sheet, the negative active material, conductive agent and other auxiliary agents in the second negative active material layer At least one of the mass ratio and the polar area density is different.
  • the negative electrode active material conductive agent acetylene black (as the first conductive agent), thickener sodium carboxymethylcellulose (CMC), and binder styrene-butadiene rubber (SBR) Mix according to the mass ratio of 95.8:1:1.2:2.
  • the first negative electrode slurry and the second negative electrode slurry are evenly coated on both surfaces of the negative electrode current collector copper foil with a thickness of 8 ⁇ m at 3.25 mg/cm 2 and 7.08 mg/cm 2 in sequence, and dried at 110°C for 20 minutes. After drying, the pole pieces are cold-pressed and cut to obtain negative electrode pole pieces with a length of 735mm and a film width of 93mm.
  • the surface density of the pole piece is 10.33mg/cm 2
  • the compacted density is 1.6g/cm 3
  • the total thickness of both sides of the pole piece is 138 ⁇ m.
  • the negative electrode active material, single-walled carbon nanotubes (as the second conductive agent), the conductive agent acetylene black (as the first conductive agent), and the thickener sodium carboxymethylcellulose (CMC) and binder styrene-butadiene rubber (SBR) are mixed at a mass ratio of 95.5:0.3:1:1.2:2.
  • the first negative electrode slurry and the second negative electrode slurry are evenly coated on both surfaces of the negative electrode current collector copper foil with a thickness of 8 ⁇ m at 3.25 mg/cm 2 and 6.1 mg/cm 2 in sequence, and dried at 110°C for 20 minutes. After drying, the pole pieces are cold-pressed and cut to obtain negative electrode pole pieces with a length of 735mm and a film width of 93mm.
  • the surface density of the pole piece is 9.35mg/cm 2
  • the compacted density is 1.6g/cm 3
  • the total thickness of both sides of the pole piece is 126 ⁇ m.
  • the negative electrode active material, single-walled carbon nanotubes (as the second conductive agent), the conductive agent acetylene black (as the first conductive agent), and the thickener sodium carboxymethylcellulose (CMC) and binder styrene-butadiene rubber (SBR) are mixed at a mass ratio of 95.3:0.5:1:1.2:2.
  • the first negative electrode slurry and the second negative electrode slurry are evenly coated on both surfaces of the negative electrode current collector copper foil with a thickness of 8 ⁇ m at 3.25 mg/cm 2 and 5.4 mg/cm 2 in sequence, and dried at 110°C for 20 minutes. After drying, the pole pieces are cold-pressed and cut to obtain negative electrode pole pieces with a length of 735mm and a film width of 93mm.
  • the surface density of the pole piece is 8.65mg/cm 2 and the compacted density is 1.6g/cm 3 .
  • the total thickness of both sides of the pole piece is 117 ⁇ m.
  • Example 15 The difference between Example 15 and Example 14 is that: the first negative active material layer in Example 14 is the same as the second negative active material layer in Example 15, and the second negative active material layer in Example 14 is the same as that in Example 14.
  • the first negative active material layer in 15 is the same.
  • the preparation of the first negative electrode slurry the negative electrode active material, single-walled carbon nanotubes (as the second conductive agent), the conductive agent acetylene black (as the first conductive agent), and the thickener sodium carboxymethylcellulose (CMC) and binder styrene-butadiene rubber (SBR) are mixed at a mass ratio of 95.3:0.5:1:1.2:2, add solvent deionized water, and stir under the action of a vacuum mixer until the system is uniform;
  • CMC carboxymethylcellulose
  • SBR binder styrene-butadiene rubber
  • Preparation of the second negative electrode slurry combine the negative active material, single-walled carbon nanotubes (as the second conductive agent), the conductive agent acetylene black (as the first conductive agent), and the thickener sodium carboxymethylcellulose (CMC) , the binder styrene-butadiene rubber (SBR) is mixed at a mass ratio of 94.8:1:1:1.2:2, add solvent deionized water, and stir under the action of a vacuum mixer until the system is uniform;
  • SBR styrene-butadiene rubber
  • the first negative electrode slurry and the second negative electrode slurry are evenly coated on both surfaces of the negative electrode current collector copper foil with a thickness of 8 ⁇ m at 5.4 mg/cm 2 and 3.25 mg/cm 2 in sequence, and dried at 110°C for 20 minutes. After drying, the pole pieces are cold-pressed and cut to obtain negative electrode pole pieces with a length of 735mm and a film width of 93mm.
  • the surface density of the pole piece is 8.65mg/cm 2 and the compacted density is 1.6g/cm 3 .
  • the total thickness of both sides of the pole piece is 117 ⁇ m.
  • Preparation of the first negative electrode slurry add the negative active material, multi-walled carbon nanotubes (as the second conductive agent), the conductive agent Ketjen Black (as the first conductive agent), and the thickener sodium carboxymethylcellulose (CMC ) and the binder styrene-butadiene rubber (SBR) are mixed at a mass ratio of 94.8:1:1:1.2:2, add solvent deionized water, and stir under the action of a vacuum mixer until the system is uniform;
  • CMC carboxymethylcellulose
  • SBR binder styrene-butadiene rubber
  • Preparation of the second negative electrode slurry combine the negative active material, multi-walled carbon nanotubes (as the second conductive agent), the conductive agent carbon black (as the first conductive agent), and the thickener sodium carboxymethylcellulose (CMC) , the binder styrene-butadiene rubber (SBR) is mixed according to the mass ratio of 95.3:0.5:1:1.2:2, add the solvent deionized water, and stir under the action of a vacuum mixer until the system is uniform;
  • SBR styrene-butadiene rubber
  • the first negative electrode slurry and the second negative electrode slurry are evenly coated on both surfaces of the negative electrode current collector copper foil with a thickness of 8 ⁇ m at 3.25 mg/cm 2 and 5.4 mg/cm 2 in sequence, and dried at 110°C for 20 minutes. After drying, the pole pieces are cold-pressed and cut to obtain negative electrode pole pieces with a length of 735mm and a film width of 93mm.
  • the surface density of the pole piece is 8.65mg/cm 2 and the compacted density is 0.705g/cm 3 .
  • the total thickness of both sides of the pole piece is 253 ⁇ m.
  • Example 17 The difference between Example 17 and Example 2 is that in Example 17, the negative active material, single-walled carbon nanotubes (as the second conductive agent), the conductive agent acetylene black (as the first conductive agent), and the thickener carboxymethyl Sodium cellulose (CMC) and binder styrene-butadiene rubber (SBR) are mixed at a mass ratio of 94.2:1.6:1:1.2:2; the pole sheet density is 6.8 mg/cm 2 .
  • CMC carboxymethyl Sodium cellulose
  • SBR binder styrene-butadiene rubber
  • the preparation method of the negative electrode piece in Comparative Example 1 is basically similar to the preparation method of the negative electrode piece in Example 1. The difference is that only the first conductive agent is included, and the negative active material of the same quality is used instead of the second conductive agent. For details, see Table 1.
  • the preparation method of the negative electrode piece in Comparative Example 2 is basically similar to the preparation method of the negative electrode piece in Example 2. The difference is that only the first conductive agent is included, and the negative active material of the same quality is used instead of the second conductive agent. For details, see Table 1.
  • the difference between the preparation method of the negative electrode sheet in Comparative Example 3 and the negative electrode sheet in Example 9 is that: the first negative active material layer only includes the first conductive agent, and the negative active material of the same quality is used instead of the second conductive agent; A negative active material layer only includes the first conductive agent, and the negative active material of the same quality is used to replace the second conductive agent. See Table 2 for details.
  • the difference between the preparation method of the negative electrode sheet in Comparative Example 4 and the negative electrode sheet in Example 10 is that: the first negative active material layer only includes the first conductive agent, and the negative active material of the same quality is used instead of the second conductive agent; A negative active material layer only includes the first conductive agent, and the negative active material of the same quality is used to replace the second conductive agent. See Table 2 for details.
  • the difference between the preparation method of the negative electrode sheet in Comparative Example 5 and the negative electrode sheet in Example 11 is that: the first negative active material layer only includes the first conductive agent, and the negative active material of the same quality is used instead of the second conductive agent; A negative active material layer only includes the first conductive agent, and the negative active material of the same quality is used to replace the second conductive agent. See Table 2 for details.
  • the difference between the preparation method of the negative electrode sheet in Comparative Example 6 and the negative electrode sheet in Example 12 is that: the first negative active material layer only includes the first conductive agent, and the negative active material of the same quality is used instead of the second conductive agent; A negative active material layer only includes the first conductive agent, and the negative active material of the same quality is used to replace the second conductive agent. See Table 2 for details.
  • the difference between the preparation method of the negative electrode sheet in Comparative Example 7 and the negative electrode sheet in Example 13 is that: the first negative active material layer only includes the first conductive agent, and the negative active material of the same quality is used instead of the second conductive agent; A negative active material layer only includes the first conductive agent, and the negative active material of the same quality is used to replace the second conductive agent. See Table 2 for details.
  • the difference between the preparation method of the negative electrode sheet in Comparative Example 8 and the negative electrode sheet in Example 14 is that: the first negative active material layer only includes the first conductive agent, and the negative active material of the same quality is used instead of the second conductive agent; A negative active material layer only includes the first conductive agent, and the negative active material of the same quality is used to replace the second conductive agent. See Table 2 for details.
  • the thickness of the material layer can adjust the conduction factor of the active material layer. See Table 1 or Table 2 for details.
  • the parameters of the negative electrode plates of Examples 1-8, 17 and Comparative Examples 1-2 are as shown in Table 1 below.
  • the parameters of the negative electrode pieces of Examples 9 to 16 and Comparative Examples 3 to 8 are as shown in Table 2 below.
  • i 0 in Table 1 and Table 2 represents the conduction factor of the negative active material layer when the negative active material layer is a single layer, or the conduction factor of the total negative active material layer when the negative active material layer is two layers; i total Indicates the conduction factor of the total negative active material layer when there are two negative active material layers.
  • i 1 indicates the conduction factor of the first negative active material layer when there are two negative active material layers.
  • i 2 indicates that the negative active material layer is The conduction factor of the second negative active material layer when there are two layers.
  • L 0 represents the thickness of the negative electrode active material layer when the negative electrode active material layer is a single layer
  • L 1 represents the thickness of the first negative electrode active material layer when the negative electrode active material layer is a double layer
  • L 2 represents the thickness of the first negative electrode active material layer when the negative electrode active material layer is a double layer The thickness of the two negative electrode active material layers.
  • r1 represents the aspect ratio of the first conductive agent
  • r2 represents the aspect ratio of the second conductive agent
  • n 01 indicates the mass proportion of the first conductive agent when the negative active material layer is a single layer
  • n 02 indicates the mass proportion of the second conductive agent when the negative active material layer is a single layer
  • n 11 indicates that the negative active material layer is two layers
  • n 12 represents the mass proportion of the second conductive agent in the first negative active material layer when the negative active material layer is two layers
  • n 21 Indicates the mass proportion of the first conductive agent in the second negative electrode active material layer when the negative electrode active material layer is two layers.
  • n 22 indicates the mass proportion of the second conductive agent in the second negative electrode active material layer when the negative electrode active material layer is two layers. The quality ratio in .
  • m 0 represents the mass ratio of the carbon-based active material and the silicon-based active material in the negative active material layer when the negative active material layer is a single layer
  • m 1 represents the carbon-based active material in the first negative active material layer when there are two negative active material layers.
  • m2 represents the mass ratio of the carbon-based active material and the silicon-based active material in the second negative active material layer when the negative active material layer is two layers.
  • SWCNT stands for single-walled carbon nanotube
  • MWCNT stands for multi-walled carbon nanotube
  • NCM 811 lithium nickel cobalt manganese oxide LiNi 0.8 Co 0.1 Mn 0.1 O 2
  • Super P conductive agent carbon black
  • PVDF binder polyvinylidene fluoride
  • NMP N-Methylpyrrolidone
  • the compacted density of the positive electrode piece is 3.5g/cm 3 and the areal density is 18.04mg/cm 2 .
  • Isolation film Polyethylene film (PE) with a thickness of 12 ⁇ m is used as the isolation film.
  • Preparation of the secondary battery Stack the positive electrode sheet, the isolation film, and the negative electrode sheet in the above embodiments or comparative examples in order, so that the isolation film plays an isolation role between the positive and negative electrode sheets, and then
  • the bare battery core is obtained by winding; the bare battery core is placed in an outer packaging shell, dried and then injected with the electrolyte prepared above. After vacuum packaging, standing, formation, shaping and other processes, a secondary battery is obtained.
  • Each prepared secondary battery was charged to 3.4V at a rate of 0.02C at 45°C, then charged to 3.75V at a rate of 0.1C.
  • the measured capacity was marked C0, and then charged to 4.25V at a rate of 0.33C at 25°C.
  • V the capacity measured by charging at 4.25V constant voltage to 0.05C is marked as C1
  • the capacity measured by discharging to 2.5V at 0.33C is marked as D0; let it stand for 5 minutes; discharge it with 0.33D0 to 2.5V; let it stand 5 minutes; charge to 4.25V at 0.33D0, charge to 0.05D0 at 4.25V constant voltage; let it stand for 5 minutes; discharge at 0.33D0 for 90 minutes.
  • the battery power is 50% of the full charge, which is called 50 % SOC; record the resting voltage after 30 minutes of rest and mark it as V0; record the voltage V1 after discharging with 4D0 for 30 seconds.
  • 50% SOC discharge DCR (V0-V1)/4D0.
  • Each prepared secondary battery was charged to 3.4V at a rate of 0.02C at 45°C, then charged to 3.75V at a rate of 0.1C.
  • the measured capacity was marked C0, and then charged to 4.25V at a rate of 0.33C at 25°C.
  • V the capacity measured by charging at 4.25V constant voltage to 0.05C is marked as C1
  • the capacity measured by discharging to 2.5V at 0.33C is marked as D0; let it stand for 5 minutes; discharge it with 0.33D0 to 2.5V; let it stand 5 minutes; charge to 4.25V at 0.33D0, charge to 0.05D0 at 4.25V constant voltage; let it stand for 5 minutes; discharge at 0.33D0 for 90 minutes.
  • the battery power is 50% of the full charge, which is called 50 % SOC; record the resting voltage after 30 minutes of rest and mark it as V2; record the voltage V3 after charging with 4D0 for 30 seconds.
  • 50% SOC charging DCR (V3-V2)/4D0.
  • the main difference between Examples 2-4 is that by adjusting the mass proportion of the second conductive agent with a large aspect ratio and the thickness of the negative active material layer, the conduction factor of the negative active material layer is adjusted; from the embodiment It can be seen from the results of 2-4 that by increasing the mass proportion of the second conductive agent with a large aspect ratio, the conduction factor of the negative active material layer can be improved, thereby improving the kinetic performance, fast charging performance and cycle performance of the secondary battery. .
  • Embodiments 14-15 The main difference between Embodiments 14-15 is that the first negative active material layer in Embodiment 14 is the same as the second negative active material layer in Embodiment 15, and the second negative active material layer in Embodiment 14 is the same as that in Embodiment 15.
  • the first negative active material layer in is the same; it can be seen from the results of Example 14 and Example 15 that when the negative active material layer is two layers, the conduction factor of the total negative active material layer satisfies 0.005 ⁇ i 0 ⁇ 3
  • the mass proportion of the silicon-based material in the first negative electrode active material layer is set to be greater than the mass proportion of the silicon-based material in the second negative electrode active material layer, and the thickness of the first negative electrode active material layer is set to be smaller than the second negative electrode active material layer.
  • the thickness of the active material layer while the conduction factor of the first negative active material layer satisfies 0.1 ⁇ i 1 ⁇ 6, and the conduction factor of the second negative active material layer satisfies 0 ⁇ i 2 ⁇ 0.75, can further improve the performance of the secondary battery. Kinetic performance, fast charging performance and cycle performance.
  • Example 1 and Comparative Example 1 From the results of Example 1 and Comparative Example 1, the results of Example 2 and Comparative Example 2, the results of Example 9 and Comparative Example 3, the results of Example 10 and Comparative Example 4, the results of Example 11 and Comparative Example 5 , the results of Example 12 and Comparative Example 6, the results of Example 13 and Comparative Example 7, and the results of Example 14 and Comparative Example 8, it can be seen that when the negative active material layer contains a linear conductive agent with a large aspect ratio , can improve the fast charging performance and cycle capacity retention rate of secondary batteries; and reduce the full charge expansion rate of the negative electrode sheet after 500 cycles, especially when the negative active material layer contains silicon-based active materials, the negative active material layer After adding the linear conductive agent, the volume expansion rate of the negative electrode plate decreased more significantly.
  • the technician analyzed the reason. This may be because the linear conductive agent can adhere to the surface of the silicon-based active material and conduct conduction for the silicon-based active material. The electrons simultaneously bind the expansion of the silicon-based material during the lithium insertion process.

Abstract

The present application relates to a negative electrode sheet, a secondary battery, and an electric apparatus. The negative electrode sheet comprises: a negative electrode current collector; and a negative electrode active material layer located on at least one surface of the negative electrode current collector, the negative electrode active material layer comprising a first conductive agent and a second conductive agent having different aspect ratios, a conduction factor of the negative electrode active material layer being denoted as i0, and the conduction factor of the negative electrode active material layer satisfying: 0.005≤i0≤3.

Description

负极极片、二次电池及用电装置Negative electrode plates, secondary batteries and electrical devices 技术领域Technical field
本申请属于二次电池技术领域，具体涉及一种负极极片、二次电池及用电装置。This application belongs to the technical field of secondary batteries, and specifically relates to a negative electrode plate, a secondary battery and an electrical device.
背景技术Background technique
二次电池因具有重量轻、无污染、无记忆效应等突出特点，被广泛应用于各类消费类电子产品和电动车辆中。随着动力电池市场的需求逐渐扩大，客户对动力电池能量密度的需求也越来越高。Secondary batteries are widely used in various consumer electronics and electric vehicles due to their outstanding characteristics such as light weight, no pollution, and no memory effect. As the demand for power batteries gradually expands, customers' demand for power battery energy density is also getting higher and higher.
但是相关技术中，采用的改善电池能量密度的技术手段在提高能量密度的同时往往会导致电池其他方面性能的劣化，例如，电池的动力学性能、快充性能和循环性能等。However, in related technologies, the technical means used to improve the energy density of batteries often lead to the degradation of other aspects of battery performance, such as the dynamic performance, fast charging performance and cycle performance of the battery, while increasing the energy density.
发明内容Contents of the invention
鉴于背景技术中存在的技术问题，本申请提供一种负极极片、二次电池及用电装置，旨在兼顾二次电池能量密度的同时使二次电池具有较好的动力学性能、快充性能和循环性能。In view of the technical problems existing in the background technology, this application provides a negative electrode plate, a secondary battery and a power device, aiming to take into account the energy density of the secondary battery while making the secondary battery have better dynamic performance and fast charging. performance and cycle performance.
为了实现上述目的，本申请的第一方面提供一种负极极片，包括：In order to achieve the above objectives, a first aspect of the present application provides a negative electrode plate, including:
负极集流体；Negative current collector;
负极活性物质层，位于所述负极集流体的至少一个表面上，所述负极活性物质层包括长径比不同的第一导电剂和第二导电剂，所述负极活性物质层的导通因子记为i 0，则所述负极活性物质层的导通因子满足：0.005≤i 0≤3； A negative active material layer is located on at least one surface of the negative current collector. The negative active material layer includes a first conductive agent and a second conductive agent with different aspect ratios. The conduction factor of the negative active material layer is expressed as is i 0 , then the conduction factor of the negative active material layer satisfies: 0.005≤i 0 ≤3;
当所述负极活性物质层为单层时，导通因子i 0＝(第一导电剂长径比*第一导电剂在负极活性物质层的质量占比)/负极活性物质层的总厚度+(第二导电剂长径比*第二导电剂在负极活性物质层的质量占比)/负极活性物质层的总厚度； When the negative active material layer is a single layer, the conduction factor i 0 =(aspect ratio of the first conductive agent*mass proportion of the first conductive agent in the negative active material layer)/total thickness of the negative active material layer+ (Aspect ratio of the second conductive agent*mass proportion of the second conductive agent in the negative active material layer)/total thickness of the negative active material layer;
当所述负极活性物质层包括第一负极活性物质层和第二负极活性物质层时，导通因子i 0＝((第一负极活性物质层中第一导电剂重量+第二负极活性物质层中第一导电剂的重量)/单位面积负极单面活性物质层的总重量*第一导电剂的长径比+(第一负极活性物质层中第二导电剂重量+第二负极活性物质层中第二导电剂的重量)/单位面积负极单面活 性物质层的总重量*第二导电剂的长径比))/活性物资层的总厚度。 When the negative active material layer includes a first negative active material layer and a second negative active material layer, the conduction factor i 0 = ((weight of the first conductive agent in the first negative active material layer + second negative active material layer weight of the first conductive agent in the unit area)/total weight of the active material layer on one side of the negative electrode per unit area*aspect ratio of the first conductive agent+(weight of the second conductive agent in the first negative active material layer+second negative active material layer The weight of the second conductive agent)/the total weight of the active material layer on one side of the negative electrode per unit area*the aspect ratio of the second conductive agent)/the total thickness of the active material layer.
相对于现有技术，本申请至少包括如下所述的有益效果：Compared with the prior art, this application at least includes the following beneficial effects:
本申请的负极极片，其设置有长径比不同的第一导电剂和第二导电剂，同时引入导通因子i 0，且导通因子i 0与导电剂的长径比和导电剂在负极活性物质层中的质量占比呈正相关，与负极活性物质层的厚度呈负相关；通过调配第一导电剂的长径比及其在负极活性物质层中的质量占比、第二导电剂的长径比及其在负极活性物质层中的质量占比和负极活性物质层的厚度，使得负极活性物质层的导通因子i 0满足0.005≤i 0≤3时，即使在较厚的负极活性物质层内仍可增大负极活性物质层中电子移动通路，使得尽可能多的负极活性材料参与充放电过程。如此上述负极极片应用于二次电池，可在兼顾二次电池能量密度的同时，提升二次电池的动力学性能、快充性能和循环性能。 The negative electrode piece of the present application is provided with a first conductive agent and a second conductive agent with different aspect ratios, and at the same time, a conduction factor i 0 is introduced, and the conduction factor i 0 is related to the aspect ratio of the conductive agent and the conductive agent. The mass proportion in the negative active material layer is positively correlated and negatively correlated with the thickness of the negative active material layer; by adjusting the aspect ratio of the first conductive agent and its mass proportion in the negative active material layer, the second conductive agent The aspect ratio and its mass proportion in the negative active material layer and the thickness of the negative active material layer make the conduction factor i 0 of the negative active material layer satisfy 0.005≤i 0 ≤3, even in a thicker negative electrode The electron movement path in the negative active material layer can still be increased in the active material layer, so that as much negative active material as possible can participate in the charge and discharge process. In this way, when the above-mentioned negative electrode plate is applied to a secondary battery, it can improve the dynamic performance, fast charging performance and cycle performance of the secondary battery while taking into account the energy density of the secondary battery.
在本申请任意实施方式中，所述第一导电剂的长径比记为a，则所述第一导电剂的长径比满足：a＜1000；In any embodiment of the present application, the aspect ratio of the first conductive agent is recorded as a, then the aspect ratio of the first conductive agent satisfies: a<1000;
可选地，所述第一导电剂包括炭黑、超导电乙炔黑、科琴黑和纳米银线中的一种或多种。Optionally, the first conductive agent includes one or more of carbon black, superconducting acetylene black, Ketjen black and nanosilver wires.
在本申请任意实施方式中，所述第二导电剂的长径比记为b，则所述第二导电剂的长径比满足：1000≤b≤10000；In any embodiment of the present application, the aspect ratio of the second conductive agent is recorded as b, then the aspect ratio of the second conductive agent satisfies: 1000≤b≤10000;
可选地，所述第二导电剂包括单壁碳纳米管和多壁碳纳米管中的一种或多种。Optionally, the second conductive agent includes one or more of single-walled carbon nanotubes and multi-walled carbon nanotubes.
在本申请任意实施方式中，所述负极活性物质层还包括负极活性材料，所述负极活性材料为碳基活性材料或碳基活性材料与硅基活性材料的混合物。In any embodiment of the present application, the negative active material layer further includes a negative active material, and the negative active material is a carbon-based active material or a mixture of a carbon-based active material and a silicon-based active material.
在本申请任意实施方式中，所述硅基活性材料包括硅、硅氧材料和硅碳材料中的一种或多种。In any embodiment of the present application, the silicon-based active material includes one or more of silicon, silicon-oxygen materials, and silicon-carbon materials.
在本申请任意实施方式中，所述负极活性物质层为单层，所述负极活性物质层的厚度为46.9～126.6μm。In any embodiment of the present application, the negative active material layer is a single layer, and the thickness of the negative active material layer is 46.9-126.6 μm.
在本申请任意实施方式中，所述第一导电剂在所述负极活性物质层中的质量占比为0.5～5％；所述第二导电剂在所述负极活性物质层中的质量占比为0.005～6％。In any embodiment of the present application, the mass proportion of the first conductive agent in the negative active material layer is 0.5 to 5%; the mass proportion of the second conductive agent in the negative active material layer It is 0.005~6%.
在本申请任意实施方式中，所述碳基活性材料与所述硅基活性材料的质量比为(75～100):(0～25)。In any embodiment of the present application, the mass ratio of the carbon-based active material to the silicon-based active material is (75-100): (0-25).
在本申请任意实施方式中，所述负极活性物质层包括：In any embodiment of the present application, the negative active material layer includes:
第一负极活性物质层，位于所述负极集流体的至少一个表面上，所述第一负极活性 物质层的导通因子记为i 1，则所述第一负极活性物质层的导通因子满足：0.1≤i 1≤6； The first negative active material layer is located on at least one surface of the negative current collector. The conduction factor of the first negative active material layer is denoted as i 1 , then the conduction factor of the first negative active material layer satisfies :0.1≤i 1 ≤6;
第二负极活性物质层，位于所述第一负极活性物质层远离所述负极集流体的表面上，所述第二负极活性物质层的导通因子记为i 2，则所述第二负极活性物质层的导通因子满足：0＜i 2≤0.75。 The second negative electrode active material layer is located on the surface of the first negative electrode active material layer away from the negative electrode current collector. The conduction factor of the second negative electrode active material layer is denoted as i 2 , then the second negative electrode active material layer The conduction factor of the material layer satisfies: 0＜i 2 ≤0.75.
在本申请任意实施方式中，所述第一负极活性物质层中硅基材料的质量占比大于所述第二负极活性物质层中硅基材料的质量占比；In any embodiment of the present application, the mass proportion of the silicon-based material in the first negative active material layer is greater than the mass proportion of the silicon-based material in the second negative active material layer;
可选地，所述第一负极活性物质层中碳基材料和硅基材料的质量比为(75～95):(5～25)；所述第二负极活性物质层中碳基材料和硅基材料的质量占比为(90～100):(0～10)。Optionally, the mass ratio of the carbon-based material and the silicon-based material in the first negative active material layer is (75-95): (5-25); the carbon-based material and silicon in the second negative active material layer are The mass ratio of the base material is (90~100): (0~10).
在本申请任意实施方式中，所述第一导电剂在所述第一负极活性物质层中的质量占比为0.5～5％；所述第二导电剂在所述第一负极活性物质层中的质量占比为0.05～6％。In any embodiment of the present application, the mass proportion of the first conductive agent in the first negative active material layer is 0.5-5%; the second conductive agent in the first negative active material layer The mass proportion is 0.05~6%.
在本申请任意实施方式中，所述第一导电剂在所述第二负极活性物质层中的质量占比为0.5～5％；所述第二导电剂在所述第二负极活性物质层中的质量占比为0～3％。In any embodiment of the present application, the mass proportion of the first conductive agent in the second negative active material layer is 0.5 to 5%; the second conductive agent in the second negative active material layer The mass proportion is 0~3%.
在本申请任意实施方式中，所述第一负极活性物质层和所述第二负极活性物质层的厚度之和为46.9～126.6μm；In any embodiment of the present application, the sum of the thicknesses of the first negative active material layer and the second negative active material layer is 46.9-126.6 μm;
可选地，所述第一负极活性物质层和所述第二负极活性物质层的厚度之比为(0.25～0.67):1。Optionally, the thickness ratio of the first negative active material layer and the second negative active material layer is (0.25˜0.67):1.
在本申请任意实施方式中，所述负极极片的极片面密度为8.4mg/cm 2～13mg/cm 2。 In any embodiment of the present application, the negative electrode sheet has a sheet density of 8.4 mg/cm 2 to 13 mg/cm 2 .
本申请的第二方面提供一种二次电池，其包括如本申请第一方面的负极极片。A second aspect of the present application provides a secondary battery, which includes the negative electrode plate of the first aspect of the present application.
本申请的第三方面提供一种用电装置，其包括如本申请第二方面的二次电池。A third aspect of the present application provides an electrical device, which includes the secondary battery of the second aspect of the present application.
附图说明Description of drawings
为了更清楚地说明本申请的技术方案，下面将对本申请中所使用的附图作简单介绍。显而易见地，下面所描述的附图仅仅是本申请的一些实施方式，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据附图获得其他的附图。In order to explain the technical solution of the present application more clearly, the drawings used in the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on the drawings without exerting creative efforts.
图1是负极极片的一实施方式的示意图。FIG. 1 is a schematic diagram of an embodiment of a negative electrode sheet.
图2是负极极片的一实施方式的示意图。FIG. 2 is a schematic diagram of an embodiment of a negative electrode plate.
图3是二次电池的一实施方式的示意图。FIG. 3 is a schematic diagram of an embodiment of a secondary battery.
图4是图3的分解图。FIG. 4 is an exploded view of FIG. 3 .
图5是电池包的一实施方式的示意图。Figure 5 is a schematic diagram of an embodiment of a battery pack.
图6是二次电池用作电源的用电装置的一实施方式的示意图。FIG. 6 is a schematic diagram of an electrical device using a secondary battery as a power source according to an embodiment.
附图标记说明：Explanation of reference symbols:
1、电池包；2、上箱体；3、下箱体；4、二次电池；41、壳体；42、电极组件；43、盖板；5、用电装置。1. Battery pack; 2. Upper box; 3. Lower box; 4. Secondary battery; 41. Shell; 42. Electrode assembly; 43. Cover; 5. Electrical device.
具体实施方式Detailed ways
下面结合具体实施方式，进一步阐述本申请。应理解，这些具体实施方式仅用于说明本申请而不用于限制本申请的范围。The present application will be further elaborated below in conjunction with specific embodiments. It should be understood that these specific embodiments are only used to illustrate the present application and are not intended to limit the scope of the present application.
为了简明，本文仅具体地公开了一些数值范围。然而，任意下限可以与任意上限组合形成未明确记载的范围；以及任意下限可以与其它下限组合形成未明确记载的范围，同样任意上限可以与任意其它上限组合形成未明确记载的范围。此外，每个单独公开的点或单个数值自身可以作为下限或上限与任意其它点或单个数值组合或与其它下限或上限组合形成未明确记载的范围。For the sake of simplicity, only certain numerical ranges are specifically disclosed herein. However, any lower limit can be combined with any upper limit to form an unexpressed range; and any lower limit can be combined with other lower limits to form an unexpressed range, and likewise any upper limit can be combined with any other upper limit to form an unexpressed range. Furthermore, each individually disclosed point or single value may itself serve as a lower or upper limit in combination with any other point or single value or with other lower or upper limits to form a range not expressly recited.
本申请所公开的“范围”以下限和上限的形式来限定，给定范围是通过选定一个下限和一个上限进行限定的，选定的下限和上限限定了特别范围的边界。这种方式进行限定的范围可以是包括端值或不包括端值的，并且可以进行任意地组合，即任何下限可以与任何上限组合形成一个范围。例如，如果针对特定参数列出了60-120和80-110的范围，理解为60-110和80-120的范围也是预料到的。此外，如果列出的最小范围值1和2，和如果列出了最大范围值3，4和5，则下面的范围可全部预料到：1-3、1-4、1-5、2-3、2-4和2-5。在本申请中，除非有其他说明，数值范围“a-b”表示a到b之间的任意实数组合的缩略表示，其中a和b都是实数。例如数值范围“0-5”表示本文中已经全部列出了“0-5”之间的全部实数，“0-5”只是这些数值组合的缩略表示。另外，当表述某个参数为≥2的整数，则相当于公开了该参数为例如整数2、3、4、5、6、7、8、9、10、11、12等。"Ranges" disclosed herein are defined in terms of lower and upper limits. A given range is defined by selecting a lower limit and an upper limit that define the boundaries of the particular range. Ranges defined in this manner may be inclusive or exclusive of the endpoints, and may be arbitrarily combined, that is, any lower limit may be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, understand that ranges of 60-110 and 80-120 are also expected. Furthermore, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2- 3, 2-4 and 2-5. In this application, unless stated otherwise, the numerical range "a-b" represents an abbreviated representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been listed in this article, and "0-5" is just an abbreviation of these numerical combinations. In addition, when stating that a certain parameter is an integer ≥ 2, it is equivalent to disclosing that the parameter is an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.
如果没有特别的说明，本申请的所有实施方式以及可选实施方式可以相互组合形成新的技术方案。If there is no special description, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions.
如果没有特别的说明，本申请的所有技术特征以及可选技术特征可以相互组合形成新的技术方案。If there is no special description, all technical features and optional technical features of the present application can be combined with each other to form new technical solutions.
如果没有特别的说明，本申请的所有步骤可以顺序进行，也可以随机进行，优选是顺序进行的。例如，所述方法包括步骤(a)和(b)，表示所述方法可包括顺序进行的步骤(a) 和(b)，也可以包括顺序进行的步骤(b)和(a)。例如，所述提到所述方法还可包括步骤(c)，表示步骤(c)可以任意顺序加入到所述方法，例如，所述方法可以包括步骤(a)、(b)和(c)，也可包括步骤(a)、(c)和(b)，也可以包括步骤(c)、(a)和(b)等。If there is no special instructions, all steps of the present application can be performed sequentially or randomly, and are preferably performed sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, mentioning that the method may also include step (c) means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b) and (c). , may also include steps (a), (c) and (b), may also include steps (c), (a) and (b), etc.
如果没有特别的说明，本申请所提到的“包括”和“包含”表示开放式，也可以是封闭式。例如，所述“包括”和“包含”可以表示还可以包括或包含没有列出的其他组分，也可以仅包括或包含列出的组分。If there is no special explanation, the words "include" and "include" mentioned in this application represent open expressions, which may also be closed expressions. For example, "comprising" and "comprising" may mean that other components not listed may also be included or included, or only the listed components may be included or included.
在本文的描述中，需要说明的是，除非另有说明，“以上”、“以下”为包括本数，“一种或几种”中“几种”的含义是两种及两种以上。In the description of this article, it should be noted that, unless otherwise stated, "above" and "below" include the original number, and "several" in "one or several" means two or more than two.
在本文的描述中，除非另有说明，术语“或(or)”是包括性的。也就是说，短语“A或(or)B”表示“A，B，或A和B两者”。更具体地，以下任一条件均满足条件“A或B”：A为真(或存在)并且B为假(或不存在)；A为假(或不存在)而B为真(或存在)；或A和B都为真(或存在)。除非另有说明，本申请中使用的术语具有本领域技术人员通常所理解的公知含义。除非另有说明，本申请中提到的各参数的数值可以用本领域常用的各种测量方法进行测量(例如，可以按照在本申请的实施例中给出的方法进行测试)。In the description herein, the term "or" is inclusive unless stated otherwise. That is, the phrase "A or (or) B" means "A, B, or both A and B." More specifically, condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists) ; Or both A and B are true (or exist). Unless otherwise stated, terms used in this application have their commonly understood meanings as generally understood by those skilled in the art. Unless otherwise stated, the values of each parameter mentioned in this application can be measured using various measurement methods commonly used in the art (for example, they can be tested according to the methods given in the examples of this application).
本申请提供的负极极片，包括：负极集流体；负极活性物质层，位于负极集流体的至少一个表面上，负极活性物质层包括长径比不同的第一导电剂和第二导电剂，负极活性物质层的导通因子记为i 0，则负极活性物质层的导通因子满足：0.005≤i 0≤3； The negative electrode sheet provided by this application includes: a negative electrode current collector; a negative electrode active material layer located on at least one surface of the negative electrode current collector. The negative electrode active material layer includes a first conductive agent and a second conductive agent with different aspect ratios. The negative electrode The conduction factor of the active material layer is recorded as i 0 , then the conduction factor of the negative active material layer satisfies: 0.005≤i 0 ≤3;
当负极活性物质层为单层时，导通因子i 0＝(第一导电剂长径比*第一导电剂在负极活性物质层的质量占比)/负极活性物质层的总厚度+(第二导电剂长径比*第二导电剂在负极活性物质层的质量占比)/负极活性物质层的总厚度； When the negative active material layer is a single layer, the conduction factor i 0 =(aspect ratio of the first conductive agent*mass proportion of the first conductive agent in the negative active material layer)/total thickness of the negative active material layer+(th The aspect ratio of the second conductive agent*the mass proportion of the second conductive agent in the negative active material layer)/the total thickness of the negative active material layer;
当负极活性物质层包括第一负极活性物质层和第二负极活性物质层时，导通因子i 0＝((第一负极活性物质层中第一导电剂重量+第二负极活性物质层中第一导电剂的重量)/单位面积负极单面活性物质层的总重量*第一导电剂的长径比+(第一负极活性物质层中第二导电剂重量+第二负极活性物质层中第二导电剂的重量)/单位面积负极单面活性物质层的总重量*第二导电剂的长径比))/活性物资层的总厚度。 When the negative active material layer includes a first negative active material layer and a second negative active material layer, the conduction factor i 0 = ((weight of the first conductive agent in the first negative active material layer + the weight of the first conductive agent in the second negative active material layer The weight of a conductive agent) / the total weight of the active material layer on one side of the negative electrode per unit area * the aspect ratio of the first conductive agent + (the weight of the second conductive agent in the first negative active material layer + the second conductive agent in the second negative active material layer The weight of the second conductive agent)/the total weight of the active material layer on one side of the negative electrode per unit area*the aspect ratio of the second conductive agent))/the total thickness of the active material layer.
不希望限于任何理论，本申请的负极极片，其设置有长径比不同的第一导电剂和第二导电剂，同时引入导通因子i 0，且导通因子i 0与导电剂的长径比和导电剂在负极活性物质层中的质量占比呈正相关，与负极活性物质层的厚度呈负相关；通过调配第一导电 剂的长径比及其在负极活性物质层中的质量占比、第二导电剂的长径比及其在负极活性物质层中的质量占比和负极活性物质层的厚度，使得负极活性物质层的导通因子i 0满足0.005≤i 0≤3时，即使在较厚的负极活性物质层内仍可增大负极活性物质层中电子移动通路，使得尽可能多的负极活性材料参与充放电过程。如此上述负极极片应用于二次电池，可在兼顾二次电池能量密度的同时，提升二次电池的动力学性能、快充性能和循环性能。 Without wishing to be limited to any theory, the negative electrode piece of the present application is provided with a first conductive agent and a second conductive agent with different aspect ratios, and at the same time, a conduction factor i 0 is introduced, and the conduction factor i 0 is related to the length of the conductive agent. The diameter ratio is positively correlated with the mass proportion of the conductive agent in the negative active material layer, and negatively correlated with the thickness of the negative active material layer; by adjusting the aspect ratio of the first conductive agent and its mass proportion in the negative active material layer ratio, the aspect ratio of the second conductive agent and its mass proportion in the negative active material layer and the thickness of the negative active material layer, so that the conduction factor i 0 of the negative active material layer satisfies 0.005 ≤ i 0 ≤3, Even in a thick negative active material layer, the electron movement path in the negative active material layer can still be increased, so that as much negative active material as possible can participate in the charge and discharge process. In this way, when the above-mentioned negative electrode plate is applied to a secondary battery, it can improve the dynamic performance, fast charging performance and cycle performance of the secondary battery while taking into account the energy density of the secondary battery.
需要说明的是，“兼顾二次电池能量密度”是指不损失或者能够提高二次电池的能量密度。It should be noted that “taking into account the energy density of the secondary battery” means that the energy density of the secondary battery is not lost or can be increased.
可理解，导电剂的长径比越大，则其形状更趋向于细长形的线状，在调整负极活性物质层中长径比较大的导电剂的质量占比时，可适当减少其用量；导电剂的长径比越小，则其形状趋向于短管状或点状，在调整负极活性物质层中长径比较小的导电剂的质量占比时，可适当增加其用量。It can be understood that the greater the aspect ratio of the conductive agent, the more elongated and linear its shape will be. When adjusting the mass proportion of the conductive agent with a large aspect ratio in the negative active material layer, its dosage can be appropriately reduced. ; The smaller the aspect ratio of the conductive agent, the shape tends to be short tube or point-like. When adjusting the mass proportion of the conductive agent with a smaller aspect ratio in the negative active material layer, its dosage can be appropriately increased.
需要说明的是，导通因子与导电剂的长径比和导电剂在负极活性物质层中的质量占比呈正相关，与负极活性物质层的厚度呈负相关，导通因子＝(导电剂长径比*导电剂在负极活性物质层的质量占比)/负极活性物质层的总厚度(μm)。具体到上述提及的负极活性物质层为单层时，负极活性物质层的导通因子i 0＝(第一导电剂长径比*第一导电剂在负极活性物质层的质量占比)/负极活性物质层的总厚度(μm)+(第二导电剂长径比*第二导电剂在负极活性物质层的质量占比)/负极活性物质层的总厚度(μm)。 It should be noted that the conduction factor is positively correlated with the aspect ratio of the conductive agent and the mass proportion of the conductive agent in the negative active material layer, and is negatively correlated with the thickness of the negative active material layer. The conduction factor = (the length of the conductive agent Diameter ratio*the mass proportion of the conductive agent in the negative active material layer)/the total thickness of the negative active material layer (μm). Specifically, when the above-mentioned negative active material layer is a single layer, the conduction factor i 0 of the negative active material layer = (aspect ratio of the first conductive agent * mass proportion of the first conductive agent in the negative active material layer)/ The total thickness of the negative active material layer (μm) + (the aspect ratio of the second conductive agent * the mass proportion of the second conductive agent in the negative active material layer) / the total thickness of the negative active material layer (μm).
负极活性物质层为单层时，负极活性物质层的导通因子i 0采用如下方法测得：1、在嵌锂前，对负极极片进行截面CP表征，测量负极活性物质层的厚度；2、在嵌锂前，称量出单位面积负极极片的重量以及单位面积负极集流体的重量，基于公式：(单位面积负极极片的重量-单位面积负极集流体的重量)/2，计算单位面积负极单面活性物质层的重量；3、将单位面积负极极片浸泡在纯水中，将所有的活性物质层洗净混合在纯水中，通过多次过滤冲洗直到粘接剂(例如，CMC,SBR等)被洗净，然后烘干得到硅基材料、碳基材料、第一导电剂和第二导电剂的混合物；4、将以上混合物通过物理分级处理，分别得到硅基材料重量、碳基材料重量以及第一导电剂重量和第二导电剂重量；5、对第一导电剂和第二导电剂分别进行SEM扫描，测量第一导电剂和第二导电剂的长径比；6、根据第一导电剂重量、单位面积负极单面活性物质层的重量，计算第一导电剂在负极活性物质层的质量占比；根据第二导电剂重量、单位面积负极单面活性物质层的重量，计算第二导电剂在负极活性物质层的质量占比；7、将上述得到的第一导电剂 的长径比及其在负极活性物质层的质量占比、第二导电剂的长径比及其在负极活性物质层的质量占比、负极活性物质层的厚度代入公式：(第一导电剂长径比*第一导电剂在负极活性物质层的质量占比)/负极活性物质层的总厚度(μm)+(第二导电剂长径比*第二导电剂在负极活性物质层的质量占比)/负极活性物质层的总厚度(μm)，计算公式计算负极活性物质层的导通因子i 0。 When the negative active material layer is a single layer, the conduction factor i 0 of the negative active material layer is measured using the following method: 1. Before embedding lithium, perform cross-sectional CP characterization of the negative electrode piece and measure the thickness of the negative active material layer; 2. , before embedding lithium, weigh out the weight of the negative electrode piece per unit area and the weight of the negative electrode current collector per unit area, based on the formula: (weight of the negative electrode piece per unit area - weight of the negative electrode current collector per unit area)/2, calculation unit The weight of the active material layer on one side of the negative electrode per area; 3. Soak the negative electrode piece per unit area in pure water, wash and mix all the active material layers in pure water, and filter and rinse multiple times until the adhesive (for example, CMC, SBR, etc.) are washed and then dried to obtain a mixture of silicon-based material, carbon-based material, first conductive agent and second conductive agent; 4. The above mixture is subjected to physical classification to obtain the weight of silicon-based material, The weight of the carbon-based material, the weight of the first conductive agent and the weight of the second conductive agent; 5. Perform SEM scanning on the first conductive agent and the second conductive agent respectively, and measure the aspect ratio of the first conductive agent and the second conductive agent; 6 , based on the weight of the first conductive agent and the weight of the active material layer on one side of the negative electrode per unit area, calculate the mass proportion of the first conductive agent in the negative active material layer; based on the weight of the second conductive agent and the weight of the active material layer on one side of the negative electrode per unit area. weight, calculate the mass proportion of the second conductive agent in the negative active material layer; 7. Combine the above-obtained aspect ratio of the first conductive agent and its mass proportion in the negative active material layer, the aspect ratio of the second conductive agent The ratio and its mass proportion in the negative active material layer and the thickness of the negative active material layer are substituted into the formula: (aspect ratio of the first conductive agent * mass proportion of the first conductive agent in the negative active material layer) / negative active material layer The total thickness (μm) + (the aspect ratio of the second conductive agent * the mass proportion of the second conductive agent in the negative active material layer) / the total thickness of the negative active material layer (μm), the calculation formula calculates the thickness of the negative active material layer Conduction factor i 0 .
负极活性物质层为由第一负极活性物质层和第二负极活性物质层构成的双层结构时，负极活性物质层的导通因子i 0＝((第一负极活性物质层中第一导电剂重量+第二负极活性物质层中第一导电剂的重量)/单位面积负极单面活性物质层的总重量*第一导电剂的长径比+(第一负极活性物质层中第二导电剂重量+第二负极活性物质层中第二导电剂的重量)/单位面积负极单面活性物质层的总重量*第二导电剂的长径比))/活性物资层的总厚度。 When the negative active material layer has a double-layer structure composed of a first negative active material layer and a second negative active material layer, the conduction factor i 0 of the negative active material layer = ((the first conductive agent in the first negative active material layer Weight + weight of the first conductive agent in the second negative electrode active material layer) / total weight of the active material layer on one side of the negative electrode per unit area * aspect ratio of the first conductive agent + ( second conductive agent in the first negative electrode active material layer Weight + weight of the second conductive agent in the second negative active material layer)/total weight of the active material layer on one side of the negative electrode per unit area*aspect ratio of the second conductive agent))/total thickness of the active material layer.
当负极活性物质层包括第一负极活性物质层和第二负极活性物质层时，总的负极活性物质层的导通因子i 0采用如下方法测得：1、在嵌锂前，对负极极片进行截面CP表征，测量总的负极活性物质层的厚度；2、在嵌锂前，称量出单位面积负极极片的重量以及单位面积负极集流体的重量，基于公式：(单位面积负极极片的重量-单位面积负极集流体的重量)/2，计算单位面积负极单面活性物质层的总重量；3、将单位面积负极极片进行上下层分离，得到第二负极活性物质层以及位于负极集流体表面的第一负极活性物质层；4、将第二负极活性物质层浸泡在纯水中，通过多次过来冲洗直到粘结剂被洗净，烘干得到第二负极活性物质层中硅基材料、碳基材料、第一导电剂和第二导电剂的混合物；并将混合物同过物理分级处理，分别得到第二负极活性物质层中硅基材料重量、碳基材料重量以及第一导电剂重量和第二导电剂重量；5、对第二负极活性物质层中的第一导电剂和第二导电剂分别进行SEM扫描，测量第二负极活性物质层中第一导电剂和第二导电剂的长径比；6、将负极集流体及位于其表面的第一负极活性物质层浸泡在纯水中，将所有的第一负极活性物质层洗净混合在纯水中，通过多次过滤冲洗直到粘结剂被洗净，烘干得到第一负极活性物质层中硅基材料、碳基材料、第一导电剂和第二导电剂的混合物；并将混合物同过物理分级处理，分别得到第一负极活性物质层中硅基材料重量、碳基材料重量以及第一导电剂重量和第二导电剂重量；7、对第一负极活性物质层中的第一导电剂和第二导电剂分别进行SEM扫描，测量第一负极活性物质层中第一导电剂和第二导电剂的长径比；8、将上述得到的各测量值代入公式：((第一负极活性物 质层中第一导电剂重量+第二负极活性物质层中第一导电剂的重量)/单位面积负极单面活性物质层的总重量*第一导电剂的长径比+(第一负极活性物质层中第二导电剂重量+第二负极活性物质层中第二导电剂的重量)/单位面积负极单面活性物质层的总重量*第二导电剂的长径比))/活性物资层的总厚度，计算总的负极活性物质层的导通因子i 0。 When the negative active material layer includes a first negative active material layer and a second negative active material layer, the conduction factor i 0 of the total negative active material layer is measured using the following method: 1. Before lithium insertion, the negative electrode piece Perform cross-sectional CP characterization and measure the thickness of the total negative active material layer; 2. Before embedding lithium, weigh the weight of the negative electrode piece per unit area and the weight of the negative electrode current collector per unit area, based on the formula: (negative electrode piece per unit area weight - the weight of the negative electrode current collector per unit area)/2, calculate the total weight of the active material layer on one side of the negative electrode per unit area; 3. Separate the upper and lower layers of the negative electrode sheet per unit area to obtain the second negative electrode active material layer and the second negative electrode active material layer located on the negative electrode. The first negative active material layer on the surface of the current collector; 4. Soak the second negative active material layer in pure water, rinse it several times until the binder is washed away, and dry to obtain the silicon in the second negative active material layer. A mixture of base material, carbon-based material, first conductive agent and second conductive agent; and the mixture is physically classified to obtain the weight of the silicon-based material, the weight of the carbon-based material and the first conductive agent in the second negative active material layer. The weight of the agent and the weight of the second conductive agent; 5. Conduct an SEM scan on the first conductive agent and the second conductive agent in the second negative active material layer, and measure the first conductive agent and the second conductive agent in the second negative active material layer. The aspect ratio of the agent; 6. Soak the negative electrode current collector and the first negative electrode active material layer on its surface in pure water, wash and mix all the first negative electrode active material layer in pure water, and filter it through multiple times Rinse until the binder is washed away, and dry to obtain a mixture of silicon-based material, carbon-based material, first conductive agent and second conductive agent in the first negative active material layer; and the mixture is subjected to physical classification to obtain respectively The weight of the silicon-based material, the weight of the carbon-based material, the weight of the first conductive agent and the weight of the second conductive agent in the first negative active material layer; 7. The first conductive agent and the second conductive agent in the first negative active material layer are respectively Carry out SEM scanning and measure the aspect ratio of the first conductive agent and the second conductive agent in the first negative active material layer; 8. Substitute each measurement value obtained above into the formula: ((The first conductive agent in the first negative active material layer Agent weight + weight of the first conductive agent in the second negative electrode active material layer) / total weight of the active material layer on one side of the negative electrode per unit area * aspect ratio of the first conductive agent + ( second conductive agent in the first negative electrode active material layer Agent weight + weight of the second conductive agent in the second negative active material layer)/total weight of the active material layer on one side of the negative electrode per unit area*aspect ratio of the second conductive agent))/total thickness of the active material layer, calculate the total The conduction factor i 0 of the negative active material layer.
本发明人经深入研究发现，当本申请的负极极片在满足上述设计条件的基础上，若还可选地满足下述条件中的一个或几个时，可以进一步提升二次电池的动力学性能、快充性能和循环性能。After in-depth research, the inventor found that when the negative electrode plate of the present application meets the above design conditions and optionally meets one or more of the following conditions, the kinetics of the secondary battery can be further improved. performance, fast charging performance and cycle performance.
在其中的一些实施例中，第一导电剂的长径比记为a，则第一导电剂的长径比满足：a＜1000；例如，第一导电剂的长径比可以满足1.01≤a≤800、1.01≤a≤200、100≤a≤500或200≤a≤800等。第一导电剂的形状趋向于短管状或点状。进一步地，第一导电剂的长径比满足：1.01≤a≤200。In some embodiments, the aspect ratio of the first conductive agent is recorded as a, then the aspect ratio of the first conductive agent satisfies: a<1000; for example, the aspect ratio of the first conductive agent can satisfy 1.01≤a ≤800, 1.01≤a≤200, 100≤a≤500 or 200≤a≤800, etc. The shape of the first conductive agent tends to be short tube-like or dot-like. Further, the aspect ratio of the first conductive agent satisfies: 1.01≤a≤200.
可选地，第一导电剂包括炭黑、超导电乙炔黑、科琴黑和纳米银线中的一种或多种。Optionally, the first conductive agent includes one or more of carbon black, superconducting acetylene black, Ketjen black and nanosilver wires.
在其中的一些实施例中，第二导电剂的长径比记为b，则第二导电剂的长径比满足：1000≤b≤10000；例如，第二导电剂的长径比可以满足1000≤b≤5000、2000≤b≤7000或5000≤b≤10000等。第二导电剂的形状趋向于细长形的线状，当负极活性物质层采用硅基活性材料时，线状的第二导电剂可附着在硅基活性材料的表面，在为硅基活性材料导通电子的同时束缚硅基材料在嵌锂过程中的膨胀。进一步地，第二导电剂的长径比满足：5000≤b≤10000。In some embodiments, the aspect ratio of the second conductive agent is recorded as b, then the aspect ratio of the second conductive agent satisfies: 1000≤b≤10000; for example, the aspect ratio of the second conductive agent can satisfy 1000 ≤b≤5000, 2000≤b≤7000 or 5000≤b≤10000, etc. The shape of the second conductive agent tends to be elongated and linear. When the negative active material layer uses a silicon-based active material, the linear second conductive agent can be attached to the surface of the silicon-based active material. In the case of a silicon-based active material While conducting electrons, it restrains the expansion of silicon-based materials during the lithium insertion process. Further, the aspect ratio of the second conductive agent satisfies: 5000≤b≤10000.
可选地，第二导电剂包括单壁碳纳米管和多壁碳纳米管中的一种或多种。Optionally, the second conductive agent includes one or more of single-walled carbon nanotubes and multi-walled carbon nanotubes.
在其中的一些实施例中，负极活性物质层还包括负极活性材料，负极活性材料为碳基活性材料或碳基活性材料与硅基活性材料的混合物。In some embodiments, the negative active material layer further includes a negative active material, and the negative active material is a carbon-based active material or a mixture of a carbon-based active material and a silicon-based active material.
可理解，负极活性材料可全部为碳基活性材料，也可以部分为碳基活性材料部分为硅基活性材料。较佳地，负极活性材料为部分为碳基活性材料，部分为硅基活性材料。硅基活性材料容量高但在嵌锂过程中其体积膨胀率过大，碳基活性材料虽然在嵌锂过程中体积膨胀率较小但其容量较硅基活性材料第，采用碳基活性材料和硅基活性材料的混合物作为负极活性材料时，可在兼顾二次电池能量密度的同时，明显改善由于硅基活性材料嵌锂导致的负极极片膨胀问题。It can be understood that the negative active material may be entirely carbon-based active material, or may be partly carbon-based active material and partly silicon-based active material. Preferably, the negative active material is partly carbon-based active material and partly silicon-based active material. Silicon-based active materials have high capacity but their volume expansion rate is too large during the lithium intercalation process. Although carbon-based active materials have a smaller volume expansion rate during the lithium intercalation process, their capacity is lower than that of silicon-based active materials. Carbon-based active materials and When a mixture of silicon-based active materials is used as a negative electrode active material, it can significantly improve the expansion problem of the negative electrode plate caused by lithium embedding in the silicon-based active material while taking into account the energy density of the secondary battery.
在其中的一些实施例中，碳基活性材料包括人造石墨和天然石墨中的一种或多种。In some embodiments, the carbon-based active material includes one or more of artificial graphite and natural graphite.
在其中的一些实施例中，硅基活性材料包括硅、硅氧材料和硅碳材料中的一种或多 种。In some embodiments, the silicon-based active material includes one or more of silicon, silicon-oxygen materials, and silicon-carbon materials.
图1是负极极片的一实施方式的示意图。在其中的一些实施例中，参照图1，负极活性物质层为单层，负极活性物质层的厚度为46.9～126.6μm；例如，可以为46.9～51.5μm、52.5～75μm、54～68μm或75～126.6μm等。技术人员经研究发现，当负极活性物质层的厚度在上述范围内时，可在兼顾二次电池能量密度的同时，使二次电池具有优异的动力学性能、快充性能和循环性能。FIG. 1 is a schematic diagram of an embodiment of a negative electrode plate. In some embodiments, referring to Figure 1, the negative active material layer is a single layer, and the thickness of the negative active material layer is 46.9-126.6 μm; for example, it can be 46.9-51.5 μm, 52.5-75 μm, 54-68 μm, or 75 μm. ~126.6μm etc. Technicians have found through research that when the thickness of the negative active material layer is within the above range, the secondary battery can have excellent dynamic performance, fast charging performance and cycle performance while taking into account the energy density of the secondary battery.
上述提及的负极活性物质层的厚度采用如下方法测得：对负极极片进行截面CP表征，测量负极活性物质层的厚度。The thickness of the above-mentioned negative electrode active material layer is measured using the following method: cross-sectional CP characterization of the negative electrode piece is performed, and the thickness of the negative electrode active material layer is measured.
在其中的一些实施例中，第一导电剂在负极活性物质层中的质量占比为0.5～5％；例如，可以为0.5～1％、1～5％或2～4％等。第二导电剂在负极活性物质层中的质量占比为0.005～6％；例如，可以为0.005～1.55％、0.87～3.1％、0.15～5％或1～6％等。In some embodiments, the mass proportion of the first conductive agent in the negative active material layer is 0.5-5%; for example, it can be 0.5-1%, 1-5%, or 2-4%. The mass proportion of the second conductive agent in the negative active material layer is 0.005-6%; for example, it can be 0.005-1.55%, 0.87-3.1%, 0.15-5% or 1-6%.
在其中的一些实施例中，碳基活性材料与硅基活性材料的质量比为(75～100):(0～25)；例如，可以为(75～85):(15～25)或(85～100):(0～15)等。In some embodiments, the mass ratio of the carbon-based active material to the silicon-based active material is (75~100): (0~25); for example, it can be (75~85): (15~25) or ( 85～100):(0～15) etc.
本申请的实施例还提供了一种负极极片的制备方法，包括：制备负极浆料，将负极浆料涂覆在负极集流体的至少一个表面上，形成负极活性物质层。Embodiments of the present application also provide a method for preparing a negative electrode sheet, including: preparing a negative electrode slurry, and coating the negative electrode slurry on at least one surface of the negative electrode current collector to form a negative electrode active material layer.
图2是负极极片的一实施方式的示意图。在其中的一些实施例中，参照图2，负极活性物质层包括：第一负极活性物质层，位于负极集流体的至少一个表面上，第一负极活性物质层的导通因子记为i 1，则第一负极活性物质层的导通因子满足：0.1≤i 1≤6；第二负极活性物质层，位于第一负极活性物质层远离负极集流体的表面上，第二负极活性物质层的导通因子记为i 2，则第二负极活性物质层的导通因子满足：0＜i 2≤0.75。 FIG. 2 is a schematic diagram of an embodiment of a negative electrode plate. In some embodiments, referring to FIG. 2 , the negative active material layer includes: a first negative active material layer located on at least one surface of the negative current collector, and the conduction factor of the first negative active material layer is denoted as i 1 , Then the conduction factor of the first negative active material layer satisfies: 0.1≤i 1 ≤6; the second negative active material layer is located on the surface of the first negative active material layer away from the negative current collector, and the conduction factor of the second negative active material layer is The pass factor is recorded as i 2 , then the conduction factor of the second negative electrode active material layer satisfies: 0＜i 2 ≤0.75.
需要说明的是，在第一负极活性物质层的导通因子i 1和第二负极活性物质层的导通因子i 2分别独立地满足上述范围时，亦可使得由第一负极活性物质层和第二负极活性物质层组成的总的负极活性物质层的导通因子i 0满足：0.005≤i 0≤3。 It should be noted that when the conduction factor i 1 of the first negative electrode active material layer and the conduction factor i 2 of the second negative electrode active material layer independently satisfy the above range, the first negative electrode active material layer and the conduction factor i 2 can also be made. The conduction factor i 0 of the total negative active material layer composed of the second negative active material layer satisfies: 0.005≤i 0 ≤3.
上述提及的导通因子i 1，导通因子i 1＝(第一导电剂长径比*第一导电剂在第一负极活性物质层的质量占比)/第一负极活性物质层的总厚度(μm)+(第二导电剂长径比*第二导电剂在第一负极活性物质层的质量占比)/第一负极活性物质层的总厚度(μm)。 The conduction factor i 1 mentioned above, the conduction factor i 1 = (aspect ratio of the first conductive agent * mass proportion of the first conductive agent in the first negative electrode active material layer) / total mass of the first negative electrode active material layer Thickness (μm) + (aspect ratio of the second conductive agent * mass proportion of the second conductive agent in the first negative active material layer)/total thickness of the first negative active material layer (μm).
导通因子i 1采用如下方法测得：1、在嵌锂前，对负极极片进行截面CP表征，测量第一负极活性物质层的厚度；2、在嵌锂前，取出单位面积负极极片进行上下层分离，得到位于负极集流体表面的第一负极活性物质层；3、称量去除第二负极活性物质层后 的单位面积负极极片的重量，以及单位面积负极集流体的重量，基于公式：(去除第二负极活性物质层后的单位面积负极极片的重量-单位面积负极集流体的重量)/2，计算单位面积负极单面第一负极活性物质层的重量；4、将负极集流体及位于其表面的第一负极活性物质层浸泡在纯水中，将所有的第一负极活性物质层洗净混合在纯水中，通过多次过滤冲洗直到粘结剂被洗净，烘干得到第一负极活性物质层中硅基材料、碳基材料、第一导电剂和第二导电剂的混合物；并将混合物同过物理分级处理，分别得到第一负极活性物质层中硅基材料重量、碳基材料重量以及第一导电剂重量和第二导电剂重量；5、对第一负极活性物质层中的第一导电剂和第二导电剂分别进行SEM扫描，测量第一负极活性物质层中第一导电剂和第二导电剂的长径比；6、根据第一负极活性物质层中第一导电剂重量、单位面积负极单面第一负极活性物质层的重量，计算第一导电剂在第一负极活性物质层的质量占比；根据第一负极活性物质层中第二导电剂重量、单位面积负极单面第一负极活性物质层的重量，计算第二导电剂在第一负极活性物质层的质量占比；7、将上述得到的第一导电剂的长径比及其在第一负极活性物质层的质量占比，第二导电剂的长径比及其在第一负极活性物质层的质量占比，第一负极活性物质层厚度代入上述导通因子i 1的计算公式计算第一负极活性物质层的导通因子。 The conduction factor i 1 is measured using the following method: 1. Before lithium embedding, perform cross-sectional CP characterization of the negative electrode piece and measure the thickness of the first negative electrode active material layer; 2. Before lithium embedding, take out the negative electrode piece per unit area Separate the upper and lower layers to obtain the first negative electrode active material layer located on the surface of the negative electrode current collector; 3. Weigh the weight of the negative electrode sheet per unit area after removing the second negative electrode active material layer, and the weight of the negative electrode current collector per unit area, based on Formula: (weight of the negative electrode sheet per unit area after removing the second negative electrode active material layer - weight of the negative electrode current collector per unit area)/2, calculate the weight of the first negative electrode active material layer on one side of the negative electrode per unit area; 4. Place the negative electrode The current collector and the first negative active material layer located on its surface are soaked in pure water. All the first negative active material layers are washed and mixed in pure water. Filter and rinse multiple times until the binder is washed and dried. The mixture of silicon-based material, carbon-based material, first conductive agent and second conductive agent in the first negative electrode active material layer is obtained by drying; and the mixture is subjected to physical classification treatment to obtain the silicon-based material in the first negative electrode active material layer. weight, the weight of the carbon-based material, the weight of the first conductive agent and the weight of the second conductive agent; 5. Conduct an SEM scan on the first conductive agent and the second conductive agent in the first negative active material layer, and measure the first negative active material The aspect ratio of the first conductive agent and the second conductive agent in the layer; 6. Calculate the first conductivity based on the weight of the first conductive agent in the first negative active material layer and the weight of the first negative active material layer on one side of the negative electrode per unit area. The mass proportion of the agent in the first negative electrode active material layer; based on the weight of the second conductive agent in the first negative electrode active material layer and the weight of the first negative electrode active material layer on one side of the negative electrode per unit area, calculate the proportion of the second conductive agent in the first negative electrode The mass proportion of the active material layer; 7. Combine the above-obtained aspect ratio of the first conductive agent and its mass proportion in the first negative electrode active material layer, the aspect ratio of the second conductive agent and its proportion in the first negative electrode The mass proportion of the active material layer and the thickness of the first negative active material layer are substituted into the above calculation formula of conduction factor i 1 to calculate the conduction factor of the first negative active material layer.
上述提及的导通因子i 2，导通因子i 2＝(第一导电剂长径比*第一导电剂在第一负极活性物质层的质量占比)/第一负极活性物质层的总厚度(μm)+(第二导电剂长径比*第二导电剂在第一负极活性物质层的质量占比)/第一负极活性物质层的总厚度(μm)。 The conduction factor i 2 mentioned above, the conduction factor i 2 = (aspect ratio of the first conductive agent * mass proportion of the first conductive agent in the first negative electrode active material layer) / total mass of the first negative electrode active material layer Thickness (μm) + (aspect ratio of the second conductive agent * mass proportion of the second conductive agent in the first negative active material layer)/total thickness of the first negative active material layer (μm).
导通因子i 2采用如下方法测得：1、在嵌锂前，对负极极片进行截面CP表征，测量第二负极活性物质层的厚度；2、在嵌锂前，取出单位面积负极极片进行上下层分离，得到单层第二负极活性物质层，并称量其重量，得到单位面积负极单面第二负极活性物质层的重量；3、将第二负极活性物质层浸泡在纯水中，通过多次过来冲洗直到粘结剂被洗净，烘干得到第二负极活性物质层中硅基材料、碳基材料、第一导电剂和第二导电剂的混合物；并将混合物同过物理分级处理，分别得到第二负极活性物质层中硅基材料重量、碳基材料重量以及第一导电剂重量和第二导电剂重量；4、对第二负极活性物质层中的第一导电剂和第二导电剂分别进行SEM扫描，测量第二负极活性物质层中第一导电剂和第二导电剂的长径比；5、根据第二负极活性物质层中第一导电剂重量、单位面积负极单面第二负极活性物质层的重量，计算第一导电剂在第二负极活性物质层的质量占比；根据第二负极活性物质层中第二导电剂重量、单位面积负极单面第二负极活性 物质层的重量，计算第二导电剂在第二负极活性物质层的质量占比；6、将上述得到的第一导电剂的长径比及其在第二负极活性物质层的质量占比，第二导电剂的长径比及其在第二负极活性物质层的质量占比，第二负极活性物质层厚度代入上述导通因子i 2的计算公式计算第一负极活性物质层的导通因子。 The conduction factor i 2 is measured using the following method: 1. Before lithium embedding, perform cross-sectional CP characterization of the negative electrode piece and measure the thickness of the second negative electrode active material layer; 2. Before lithium embedding, take out the negative electrode piece per unit area Separate the upper and lower layers to obtain a single layer of the second negative active material layer, and weigh its weight to obtain the weight of the second negative active material layer on one side of the negative electrode per unit area; 3. Soak the second negative active material layer in pure water , rinse repeatedly until the binder is washed, and dry to obtain a mixture of silicon-based material, carbon-based material, first conductive agent, and second conductive agent in the second negative active material layer; and the mixture is subjected to physical Grading processing to obtain the weight of the silicon-based material, the weight of the carbon-based material, the weight of the first conductive agent and the weight of the second conductive agent in the second negative active material layer respectively; 4. Calculate the first conductive agent and the weight of the second conductive agent in the second negative active material layer Conduct SEM scanning of the second conductive agent respectively, and measure the aspect ratio of the first conductive agent and the second conductive agent in the second negative electrode active material layer; 5. According to the weight of the first conductive agent in the second negative electrode active material layer, the negative electrode per unit area The weight of the second negative electrode active material layer on one side is used to calculate the mass proportion of the first conductive agent in the second negative electrode active material layer; based on the weight of the second conductive agent in the second negative electrode active material layer and the second negative electrode on one side of the negative electrode per unit area According to the weight of the active material layer, calculate the mass proportion of the second conductive agent in the second negative electrode active material layer; 6. Combine the aspect ratio of the first conductive agent obtained above and its mass proportion in the second negative electrode active material layer , the aspect ratio of the second conductive agent and its mass proportion in the second negative active material layer, the thickness of the second negative active material layer is substituted into the calculation formula of the above conduction factor i 2 to calculate the conduction of the first negative active material layer factor.
在其中的一些实施例中，第一负极活性物质层中硅基材料的质量占比大于第二负极活性物质层中硅基材料的质量占比。通过设置两个负极活性物质层，并且将含硅基材料的质量占比低的第二负极活性物质层设置在远离负极集流体的外层，如此负极极片应用于二次电池时，充电时锂离子会优先嵌入第二负极活性物质层，在循环过程中第二负极活性物质层满充满放循环，靠近负极集流体的第一负极活性物质层非满充满放循环，在第一负极活性物质层中设置较多的硅基材料不但可保证二次电池的具有较高的能量密度，同时第一负极活性物质层中的硅基材料不会产生过大的膨胀效应。此外，二次电池的电化学性能受第二负极活性物质层的影响更大，在第二负极活性物质层中设置较多的碳基材料可使二次电池的循环和存储性能更优。In some embodiments, the mass proportion of the silicon-based material in the first negative active material layer is greater than the mass proportion of the silicon-based material in the second negative active material layer. By arranging two negative electrode active material layers, and arranging the second negative electrode active material layer with a low mass proportion of silicon-based material on the outer layer away from the negative electrode current collector, when the negative electrode sheet is used in a secondary battery, the Lithium ions will be preferentially embedded in the second negative electrode active material layer. During the cycle, the second negative electrode active material layer is fully charged and discharged. The first negative active material layer close to the negative electrode current collector is not fully charged and discharged. During the cycle, the first negative electrode active material layer is filled with discharge. Providing more silicon-based materials in the layer not only ensures that the secondary battery has a higher energy density, but at the same time, the silicon-based material in the first negative active material layer will not produce an excessive expansion effect. In addition, the electrochemical performance of the secondary battery is more affected by the second negative active material layer. Providing more carbon-based materials in the second negative active material layer can improve the cycle and storage performance of the secondary battery.
技术人员经研究发现，第一负极活性物质层内硅基材料的质量占比较大，第一负极活性物质层的导通因子i 1在上述范围时，其内线状的导电剂的质量占比较大，可在为硅基活性材料导通电子的同时减小硅基材料在嵌锂过程中的膨胀；第二负极活性物质层内碳基材料的质量占比较大，第二负极活性物质层的导通因子i 2在上述范围时，便可使二次电池具有较好的电化学性能。 Technicians found through research that the mass proportion of silicon-based materials in the first negative active material layer is relatively large. When the conduction factor i 1 of the first negative active material layer is in the above range, the mass proportion of the linear conductive agent in it is relatively large. , which can conduct electrons for the silicon-based active material while reducing the expansion of the silicon-based material during the lithium insertion process; the carbon-based material in the second negative electrode active material layer accounts for a large proportion of the mass, and the conduction of the second negative electrode active material layer When the pass factor i 2 is within the above range, the secondary battery can have better electrochemical performance.
可选地，第一负极活性物质层中碳基材料和硅基材料的质量比为(75～95):(5～25)；例如，可以为(75～85):(15～25)或(85～95):(5～15)等。Optionally, the mass ratio of the carbon-based material and the silicon-based material in the first negative active material layer is (75~95): (5~25); for example, it can be (75~85): (15~25) or (85～95): (5～15) etc.
第二负极活性物质层中碳基材料和硅基材料的质量占比为(90～100):(0～10)；例如，可以为(90～95):(5～10)、(95～100):(0～5)或(90～98):(2～10)等。The mass ratio of the carbon-based material and the silicon-based material in the second negative electrode active material layer is (90~100): (0~10); for example, it can be (90~95): (5~10), (95~ 100): (0～5) or (90～98): (2～10) etc.
在其中的一些实施例中，第一导电剂在第一负极活性物质层中的质量占比为0.5～5％；例如，可以为0.5～1.2％、1.5～3％或1～5％等。第二导电剂在第一负极活性物质层中的质量占比为0.05～6％；例如，可以为0.05～1％、0.3～2.1％或2.1～6％等。In some embodiments, the mass proportion of the first conductive agent in the first negative active material layer is 0.5-5%; for example, it can be 0.5-1.2%, 1.5-3%, or 1-5%. The mass proportion of the second conductive agent in the first negative active material layer is 0.05-6%; for example, it can be 0.05-1%, 0.3-2.1%, or 2.1-6%.
在其中的一些实施例中，第一导电剂在第二负极活性物质层中的质量占比为0.5～5％；例如，可以为0.5～1％、1～4％或2～5％等。第二导电剂在第二负极活性物质层中的质量占比为0～3％；例如，可以为0～0.5％、0.3～1％或1～3％等。In some embodiments, the mass proportion of the first conductive agent in the second negative electrode active material layer is 0.5-5%; for example, it can be 0.5-1%, 1-4%, or 2-5%. The mass proportion of the second conductive agent in the second negative electrode active material layer is 0 to 3%; for example, it can be 0 to 0.5%, 0.3 to 1%, or 1 to 3%.
在其中的一些实施例中，第一负极活性物质层和第二负极活性物质层的厚度之和为 46.9～126.6μm。技术人员经研究发现，当第一负极活性物质层和第二负极活性物质层的厚度之和在上述范围内时，可在兼顾二次电池能量密度的同时，使二次电池具有优异的动力学性能、快充性能和循环性能。In some embodiments, the sum of the thicknesses of the first negative active material layer and the second negative active material layer is 46.9-126.6 μm. Technicians have found through research that when the sum of the thicknesses of the first negative electrode active material layer and the second negative electrode active material layer is within the above range, the secondary battery can have excellent kinetics while taking into account the energy density of the secondary battery. performance, fast charging performance and cycle performance.
可选地，第一负极活性物质层和第二负极活性物质层的厚度之比为(0.25～0.67):1。通过将第二负极活性物质层的厚度设置为大于第一负极活性物质层的厚度，有利于第二负极活性物质层和第一负极活性物质层形成梯度孔隙分布，使得正极脱出活性离子在负极膜层表面的液相传导阻力减小，可避免活性离子在负极膜层表面堆积引起析锂问题，同时活性离子在负极膜层中的均匀扩散有利于减小极化，进一步提升二次电池的动力学性能和循环性能。Optionally, the thickness ratio of the first negative active material layer and the second negative active material layer is (0.25˜0.67):1. By setting the thickness of the second negative electrode active material layer to be greater than the thickness of the first negative electrode active material layer, it is beneficial to form a gradient pore distribution between the second negative electrode active material layer and the first negative electrode active material layer, so that the active ions released from the positive electrode are dispersed in the negative electrode membrane. The liquid phase conduction resistance on the surface of the layer is reduced, which can avoid the accumulation of active ions on the surface of the negative electrode film layer and cause lithium precipitation. At the same time, the uniform diffusion of active ions in the negative electrode film layer is conducive to reducing polarization and further improving the power of the secondary battery. chemical performance and cycle performance.
上述提及的第一负极活性物质层和第二负极活性物质层的厚度之比采用如下方法测得：在嵌锂前，对负极极片进行截面CP表征，分别测定第一负极活性物质层的厚度和第二负极活性物质层的厚度，然后计算第一负极活性物质层的厚度与第二负极活性物质层的厚度的比值。The ratio of the thickness of the first negative electrode active material layer and the second negative electrode active material layer mentioned above is measured using the following method: before lithium embedding, perform cross-sectional CP characterization of the negative electrode piece, and measure the thickness of the first negative electrode active material layer respectively. thickness and the thickness of the second negative electrode active material layer, and then calculate the ratio of the thickness of the first negative electrode active material layer to the thickness of the second negative electrode active material layer.
在其中的一些实施例中，负极极片的极片面密度为8.4mg/cm 2～13mg/cm 2。技术人员经研究发现，负极极片的极片密度在上述范围时，可进一步改善负极极片的能量密度和快充性能。 In some embodiments, the negative electrode piece has an area density of 8.4 mg/cm 2 to 13 mg/cm 2 . Technicians have found through research that when the density of the negative electrode piece is within the above range, the energy density and fast charging performance of the negative electrode piece can be further improved.
上述提及的负极极片的极片面密度采用如下方法测得：采用冲切模具冲切出1cm 2的负极极片，然后称重得到1cm 2极片的总重量M0；冲切1cm 2的负极极片用纯水将活性物质层清洗掉，然后称重得到负极集流体的重量M1，则基于公式(M0-M1)/2计算负极极片的极片面密度。 The surface density of the above-mentioned negative electrode piece is measured using the following method: Use a punching die to punch out a 1cm 2 negative electrode piece, and then weigh it to obtain the total weight M0 of the 1cm 2 piece; punch out a 1cm 2 negative electrode Clean the active material layer of the electrode piece with pure water, and then weigh it to obtain the weight M1 of the negative electrode current collector. Then calculate the electrode piece surface density of the negative electrode piece based on the formula (M0-M1)/2.
本申请的实施例还提供了一种负极极片的制备方法，包括如下步骤：Embodiments of the present application also provide a method for preparing a negative electrode sheet, including the following steps:
S1、制备第一负极浆料，将第一负极浆料涂覆在负极集流体的至少一个表面上，形成第一负极活性物质层；S1. Prepare a first negative electrode slurry, and coat the first negative electrode slurry on at least one surface of the negative electrode current collector to form a first negative electrode active material layer;
S2、制备第二负极浆料，将第二负极浆料涂覆在第一负极活性物质层远离极集流体的表面上，形成第二负极活性物质层。S2. Prepare a second negative electrode slurry, and apply the second negative electrode slurry on the surface of the first negative electrode active material layer away from the electrode current collector to form a second negative electrode active material layer.
负极集流体可以采用常规金属箔片或复合集流体。作为示例，金属箔片可以采用铜箔。复合集流体可包括高分子材料基层和形成于高分子材料基材至少一个表面上的金属层。复合集流体可通过将金属材料(铜、铜合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚 对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等的基材)上而形成。The negative electrode current collector can use conventional metal foil or composite current collector. As an example, the metal foil may be copper foil. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base material. The composite current collector can be formed by forming metal materials (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as polypropylene (PP), polyterephthalate It is formed on substrates such as ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
负极活性物质层通常还包括导电剂、粘结剂和其他可选助剂。The negative active material layer usually also includes conductive agents, binders and other optional auxiliaries.
作为示例，导电剂可以为超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中一种或几种。所述导电剂在负极膜层中的重量比为0～20重量％，基于负极膜层的总重量计。As an example, the conductive agent may be one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers. The weight ratio of the conductive agent in the negative electrode film layer is 0 to 20% by weight, based on the total weight of the negative electrode film layer.
作为示例，粘结剂可选自丁苯橡胶(SBR)、聚丙烯酸(PAA)、聚丙烯酸钠(PAAS)、聚丙烯酰胺(PAM)、聚乙烯醇(PVA)、海藻酸钠(SA)、聚甲基丙烯酸(PMAA)及羧甲基壳聚糖(CMCS)中的至少一种。所述粘结剂在负极膜层中的重量比为0-30重量％，基于负极膜层的总重量计。As an example, the binder may be selected from styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), At least one of polymethacrylic acid (PMAA) and carboxymethyl chitosan (CMCS). The weight ratio of the binder in the negative electrode film layer is 0-30% by weight, based on the total weight of the negative electrode film layer.
作为示例，其他可选助剂可以是PTC热敏电阻材料等。所述其他助剂在负极膜层中的重量比为0～15重量％，基于负极膜层的总重量计。As an example, other optional additives may be PTC thermistor materials, etc. The weight ratio of the other additives in the negative electrode film layer is 0 to 15% by weight, based on the total weight of the negative electrode film layer.
上述原料为特别说明的均可以通过市购获得。The above-mentioned raw materials are all commercially available unless otherwise specified.
二次电池secondary battery
二次电池，是指在电池放电后可通过充电的方式使活性材料激活而继续使用的电池。Secondary batteries refer to batteries that can be recharged to activate active materials and continue to be used after the battery is discharged.
通常情况下，二次电池包括正极极片、本申请上述提供的负极极片、隔离膜及电解液。在电池充放电过程中，活性离子在正极极片和负极极片之间往返嵌入和脱出。隔离膜设置在正极极片和负极极片之间，起到隔离的作用。电解液在正极极片和负极极片之间起到传导离子的作用。Normally, a secondary battery includes a positive electrode sheet, the negative electrode sheet provided above in this application, a separator and an electrolyte. During the charging and discharging process of the battery, active ions are inserted and detached back and forth between the positive and negative electrodes. The isolation film is arranged between the positive electrode piece and the negative electrode piece to play the role of isolation. The electrolyte plays a role in conducting ions between the positive and negative electrodes.
正极极片Positive electrode piece
在二次电池中，正极极片通常包括正极集流体及设置在正极集流体至少一个表面上的正极膜层，正极膜层包括正极活性材料。In secondary batteries, a positive electrode sheet usually includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector. The positive electrode film layer includes a positive electrode active material.
作为示例，正极集流体具有在其自身厚度方向相对的两个表面，正极膜层设置在正极集流体相对的两个表面的其中任意一者或两者上。As an example, the positive electrode current collector has two surfaces facing each other in its own thickness direction, and the positive electrode film layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.
作为示例，正极集流体可采用金属箔片或复合集流体。例如，作为金属箔片，可采用铝箔。复合集流体可包括高分子材料基层和形成于高分子材料基层至少一个表面上的金属层。复合集流体可通过将金属材料(铝、铝合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等的基材)上而形成。As an example, the positive electrode current collector may use a metal foil or a composite current collector. For example, as the metal foil, aluminum foil can be used. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector can be formed by forming metal materials (aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver and silver alloys, etc.) on polymer material substrates (such as polypropylene (PP), polyterephthalate It is formed on substrates such as ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
当二次电池为锂离子电池时，正极活性材料可采用本领域公知的用于锂离子电池的正极活性材料。作为示例，正极活性材料可包括以下材料中的至少一种：橄榄石结构的含锂磷酸盐、锂过渡金属氧化物及其各自的改性化合物。但本申请并不限定于这些材料，还可以使用其他可被用作电池正极活性材料的传统材料。这些正极活性材料可以仅单独使用一种，也可以将两种以上组合使用。其中，锂过渡金属氧化物的示例可包括但不限于锂钴氧化物(如LiCoO 2)、锂镍氧化物(如LiNiO 2)、锂锰氧化物(如LiMnO 2、LiMn 2O 4)、锂镍钴氧化物、锂锰钴氧化物、锂镍锰氧化物、锂镍钴锰氧化物(如LiNi 1/3Co 1/3Mn 1/3O 2(也可以简称为NCM 333)、LiNi 0.5Co 0.2Mn 0.3O 2(也可以简称为NCM 523)、LiNi 0.5Co 0.25Mn 0.25O 2(也可以简称为NCM 211)、LiNi 0.6Co 0.2Mn 0.2O 2(也可以简称为NCM 622)、LiNi 0.8Co 0.1Mn 0.1O 2(也可以简称为NCM 811)、锂镍钴铝氧化物(如LiNi 0.85Co 0.15Al 0.05O 2)及其改性化合物等中的至少一种。橄榄石结构的含锂磷酸盐的示例可包括但不限于磷酸铁锂(如LiFePO 4(也可以简称为LFP))、磷酸铁锂与碳的复合材料、磷酸锰锂(如LiMnPO 4)、磷酸锰锂与碳的复合材料、磷酸锰铁锂、磷酸锰铁锂与碳的复合材料中的至少一种。所述正极活性材料在正极膜层中的重量比为80～100重量％，基于正极膜层的总重量计。 When the secondary battery is a lithium ion battery, the cathode active material may be a cathode active material known in the art for lithium ion batteries. As an example, the cathode active material may include at least one of the following materials: an olivine-structured lithium-containing phosphate, a lithium transition metal oxide, and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials of batteries can also be used. Only one type of these positive electrode active materials may be used alone, or two or more types may be used in combination. Examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxides (such as LiCoO 2 ), lithium nickel oxides (such as LiNiO 2 ), lithium manganese oxides (such as LiMnO 2 , LiMn 2 O 4 ), lithium Nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1/3 Co 1/3 Mn 1/3 O 2 (also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O 2 (can also be abbreviated to NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O 2 (can also be abbreviated to NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O 2 (can also be abbreviated to NCM 622 ), LiNi At least one of 0.8 Co 0.1 Mn 0.1 O 2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05 O 2 ) and its modified compounds. The olivine structure contains Examples of lithium phosphates may include, but are not limited to, lithium iron phosphate (such as LiFePO 4 (also referred to as LFP)), composites of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO 4 ), lithium manganese phosphate and carbon. At least one of composite materials, lithium iron manganese phosphate, and composite materials of lithium iron manganese phosphate and carbon. The weight ratio of the positive electrode active material in the positive electrode film layer is 80 to 100% by weight, based on the total weight of the positive electrode film layer count.
当二次电池为钠离子电池时，正极活性材料可采用本领域公知的用于钠离子电池的正极活性材料。作为示例，正极活性材料可以仅单独使用一种，也可以将两种以上组合。其中，正极活性物质可选自钠铁复合氧化物(NaFeO 2)、钠钴复合氧化物(NaCoO 2)、钠铬复合氧化物(NaCrO 2)、钠锰复合氧化物(NaMnO 2)、钠镍复合氧化物(NaNiO 2)、钠镍钛复合氧化物(NaNi 1/2Ti 1/2O 2)、钠镍锰复合氧化物(NaNi 1/2Mn 1/2O 2)、钠铁锰复合氧化物(Na 2/3Fe 1/3Mn 2/3O 2)、钠镍钴锰复合氧化物(NaNi 1/3Co 1/3Mn 1/3O 2)、钠铁磷酸化合物(NaFePO 4)、钠锰磷酸化合物(NaMn PO 4)、钠钴磷酸化合物(NaCoPO 4)、普鲁士蓝类材料、聚阴离子材料(磷酸盐、氟磷酸盐、焦磷酸盐、硫酸盐)等，但本申请并不限定于这些材料，本申请还可以使用其他可被用作钠离子电池正极活性物质的传统公知的材料。所述正极活性材料在正极膜层中的重量比为80～100重量％，基于正极膜层的总重量计。 When the secondary battery is a sodium-ion battery, the cathode active material may be a cathode active material known in the art for sodium-ion batteries. As an example, only one type of positive electrode active material may be used alone, or two or more types may be combined. Among them, the positive active material can be selected from sodium iron composite oxide (NaFeO 2 ), sodium cobalt composite oxide (NaCoO 2 ), sodium chromium composite oxide (NaCrO 2 ), sodium manganese composite oxide (NaMnO 2 ), sodium nickel Composite oxide (NaNiO 2 ), sodium nickel titanium composite oxide (NaNi 1/2 Ti 1/2 O 2 ), sodium nickel manganese composite oxide (NaNi 1/2 Mn 1/2 O 2 ), sodium iron manganese composite Oxide (Na 2/3 Fe 1/3 Mn 2/3 O 2 ), sodium nickel cobalt manganese composite oxide (NaNi 1/3 Co 1/3 Mn 1/3 O 2 ), sodium iron phosphate compound (NaFePO 4 ), sodium manganese phosphate compound (NaMn P O 4 ), sodium cobalt phosphate compound (NaCoPO 4 ), Prussian blue materials, polyanionic materials (phosphates, fluorophosphates, pyrophosphates, sulfates), etc., but this application It is not limited to these materials, and other conventionally known materials that can be used as positive electrode active materials of sodium ion batteries can also be used in this application. The weight ratio of the positive electrode active material in the positive electrode film layer is 80 to 100% by weight, based on the total weight of the positive electrode film layer.
所述正极膜层通常还可选地包括粘结剂、导电剂和其他可选助剂。The positive electrode film layer also optionally includes binders, conductive agents and other optional auxiliaries.
作为示例，所述粘结剂可以包括聚偏氟乙烯(PVDF)、聚四氟乙烯(PTFE)、偏氟乙烯-四氟乙烯-丙烯三元共聚物、偏氟乙烯-六氟丙烯-四氟乙烯三元共聚物、四氟乙烯-六氟丙烯共聚物及含氟丙烯酸酯树脂中的至少一种。所述粘结剂在正极膜层中的重 量比为0～20重量％，基于正极膜层的总重量计。As examples, the binder may include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene At least one of ethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer and fluorine-containing acrylate resin. The weight ratio of the binder in the positive electrode film layer is 0 to 20% by weight, based on the total weight of the positive electrode film layer.
作为示例，所述导电剂可以包括超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的至少一种。所述导电剂在正极膜层中的重量比为0～20重量％，基于正极膜层的总重量计。As an example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers. The weight ratio of the conductive agent in the positive electrode film layer is 0 to 20% by weight, based on the total weight of the positive electrode film layer.
作为示例，可以通过以下方式制备正极极片：将上述用于制备正极极片的组分，例如正极活性材料、导电剂、粘结剂和任意其他的组分分散于溶剂(例如N-甲基吡咯烷酮)中，形成正极浆料，其中所述正极浆料固含量为40～80wt％，室温下的粘度调整到5000～25000mPa·s；将正极浆料涂覆在正极集流体上，经烘干、冷压等工序后，即可得到正极极片；正极粉末涂布单位面密度为150～350mg/m 2，正极极片压实密度为3.0～3.6g/cm 3，可选为3.3～3.5g/cm 3。所述压实密度的计算公式为 As an example, the positive electrode sheet can be prepared in the following manner: the above-mentioned components for preparing the positive electrode sheet, such as the positive active material, the conductive agent, the binder and any other components are dispersed in a solvent (such as N-methyl pyrrolidone) to form a positive electrode slurry, wherein the solid content of the positive electrode slurry is 40 to 80 wt%, and the viscosity at room temperature is adjusted to 5000 to 25000 mPa·s; the positive electrode slurry is coated on the positive electrode current collector and dried , cold pressing and other processes, the positive electrode piece can be obtained; the unit area density of the positive electrode powder coating is 150~350 mg/m 2 , and the compacted density of the positive electrode piece is 3.0~3.6g/cm 3 , optionally 3.3~3.5 g/cm 3 . The calculation formula of the compacted density is
压实密度＝涂布面密度/(挤压后极片厚度-集流体厚度)。Compaction density = coating surface density / (thickness of electrode piece after extrusion - thickness of current collector).
隔离膜Isolation film
在一些实施方式中，二次电池中还包括隔离膜。本申请对隔离膜的种类没有特别的限制，可以选用任意公知的具有良好的化学稳定性和机械稳定性的多孔结构隔离膜。In some embodiments, the secondary battery further includes a separator film. There is no particular restriction on the type of isolation membrane in this application. Any well-known porous structure isolation membrane with good chemical stability and mechanical stability can be used.
在一些实施方式中，隔离膜的材质可选自玻璃纤维、无纺布、聚乙烯、聚丙烯及聚偏二氟乙烯中的至少一种。隔离膜可以是单层薄膜，也可以是多层复合薄膜，没有特别限制。在隔离膜为多层复合薄膜时，各层的材料可以相同或不同，没有特别限制。In some embodiments, the material of the isolation membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride. The isolation film can be a single-layer film or a multi-layer composite film, with no special restrictions. When the isolation film is a multi-layer composite film, the materials of each layer can be the same or different, and there is no particular limitation.
在一些实施方式中，所述隔离膜的厚度为6～40μm，可选为12～20μm。In some embodiments, the thickness of the isolation film is 6-40 μm, optionally 12-20 μm.
在一些实施方式中，正极极片、负极极片和隔离膜可通过卷绕工艺或叠片工艺制成电极组件。In some embodiments, the positive electrode piece, the negative electrode piece and the separator film can be made into an electrode assembly through a winding process or a lamination process.
电解液electrolyte
二次电池可以包括电解液，电解液在正极和负极之间起到传导离子的作用。电解液可以包括电解质盐和溶剂。The secondary battery may include an electrolyte that serves to conduct ions between a positive electrode and a negative electrode. The electrolyte solution may include electrolyte salts and solvents.
作为示例，电解质盐可选自六氟磷酸锂(LiPF 6)、四氟硼酸锂(LiBF 4)、高氯酸锂(LiClO 4)、六氟砷酸锂(LiAsF 6)、双氟磺酰亚胺锂(LiFSI)、双三氟甲磺酰亚胺锂(LiTFSI)、三氟甲磺酸锂(LiTFS)、二氟草酸硼酸锂(LiDFOB)、二草酸硼酸锂(LiBOB)、二氟磷酸锂(LiPO 2F 2)、二氟二草酸磷酸锂(LiDFOP)及四氟草酸磷酸锂(LiTFOP)中的一种或几种。所述电解质盐的浓度通常为0.5～5mol/L。 As an example, the electrolyte salt may be selected from lithium hexafluorophosphate (LiPF 6 ), lithium tetrafluoroborate (LiBF 4 ), lithium perchlorate (LiClO 4 ), lithium hexafluoroarsenate (LiAsF 6 ), lithium bisfluorosulfonyl imide ( LiFSI), lithium bistrifluoromethanesulfonimide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluoromethanesulfonate borate (LiDFOB), lithium dioxalatoborate (LiBOB), lithium difluorophosphate (LiPO 2 F 2 ), one or more of lithium difluorodioxalate phosphate (LiDFOP) and lithium tetrafluorooxalate phosphate (LiTFOP). The concentration of the electrolyte salt is usually 0.5 to 5 mol/L.
作为示例，所述溶剂可选自碳酸亚乙酯(EC)、碳酸亚丙酯(PC)、碳酸甲乙酯 (EMC)、碳酸二乙酯(DEC)、碳酸二甲酯(DMC)、碳酸二丙酯(DPC)、碳酸甲丙酯(MPC)、碳酸乙丙酯(EPC)、碳酸亚丁酯(BC)、氟代碳酸亚乙酯(FEC)、甲酸甲酯(MF)、乙酸甲酯(MA)、乙酸乙酯(EA)、乙酸丙酯(PA)、丙酸甲酯(MP)、丙酸乙酯(EP)、丙酸丙酯(PP)、丁酸甲酯(MB)、丁酸乙酯(EB)、1,4-丁内酯(GBL)、环丁砜(SF)、二甲砜(MSM)、甲乙砜(EMS)及二乙砜(ESE)中的一种或几种。As an example, the solvent may be selected from ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), carbonic acid Dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), One or more of ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS) and diethyl sulfone (ESE) .
在一些实施方式中，电解液中还包括添加剂。例如添加剂可以包括负极成膜添加剂，也可以包括正极成膜添加剂，还可以包括能够改善电池某些性能的添加剂，例如改善电池过充性能的添加剂、改善电池高温性能的添加剂、改善电池低温性能的添加剂等。In some embodiments, additives are also included in the electrolyte. For example, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain properties of the battery, such as additives that improve the overcharge performance of the battery, additives that improve the high-temperature performance of the battery, and additives that improve the low-temperature performance of the battery. Additives etc.
在一些实施方式中，本申请的二次电池为锂离子二次电池。In some embodiments, the secondary battery of the present application is a lithium-ion secondary battery.
可以按照本领域常规方法制备二次电池，例如将正极极片、隔离膜、负极极片按顺序卷绕(或叠片)，使隔离膜处于正极极片与负极极片之间起到隔离的作用，得到电芯，将电芯置于外包装中，注入电解液并封口，得到二次电池。The secondary battery can be prepared according to conventional methods in the art, for example, the positive electrode sheet, the separator film, and the negative electrode sheet are wound (or stacked) in order, so that the separator film is between the positive electrode sheet and the negative electrode sheet for isolation. function to obtain the battery core, place the battery core in the outer package, inject the electrolyte and seal it to obtain a secondary battery.
本申请实施例对二次电池的形状没有特别的限制，其可以是圆柱形、方形或其他任意的形状。如图3是作为一个示例的方形结构的二次电池4。The embodiments of the present application have no particular limitation on the shape of the secondary battery, which may be cylindrical, square, or any other shape. FIG. 3 shows an example of a square-structured secondary battery 4 .
在一些实施例中，二次电池可包括外包装。该外包装可用于封装上述电极组件及电解液。In some embodiments, the secondary battery may include an outer packaging. The outer packaging can be used to package the above-mentioned electrode assembly and electrolyte.
在一些实施例中，二次电池的外包装可以是硬壳，例如硬塑料壳、铝壳、钢壳等。二次电池的外包装也可以是软包，例如袋式软包。软包的材质可以是塑料，作为塑料，可列举出聚丙烯、聚对苯二甲酸丁二醇酯以及聚丁二酸丁二醇酯等。In some embodiments, the outer packaging of the secondary battery may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer packaging of the secondary battery may also be a soft bag, such as a bag-type soft bag. The material of the soft bag may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, polybutylene succinate, and the like.
在一些实施例中，参照图4，外包装可包括壳体41和盖板43。其中，壳体41可包括底板和连接于底板上的侧板，底板和侧板围合形成容纳腔。壳体41具有与容纳腔连通的开口，盖板43能够盖设于所述开口，以封闭所述容纳腔。In some embodiments, referring to FIG. 4 , the outer package may include a housing 41 and a cover 43 . The housing 41 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and the side plates enclose a receiving cavity. The housing 41 has an opening communicating with the accommodation cavity, and the cover plate 43 can cover the opening to close the accommodation cavity.
正极极片、负极极片和隔离膜可经卷绕工艺或叠片工艺形成电极组件42。电极组件52封装于所述容纳腔。电解液浸润于电极组件42中。二次电池4所含电极组件42的数量可以为一个或多个，可根据需求来调节。The positive electrode piece, the negative electrode piece and the isolation film can be formed into the electrode assembly 42 through a winding process or a lamination process. The electrode assembly 52 is packaged in the containing cavity. The electrolyte soaks into the electrode assembly 42 . The number of electrode assemblies 42 contained in the secondary battery 4 can be one or more, and can be adjusted according to requirements.
在一些实施例中，上述二次电池还可以组装成电池包，电池包所含二次电池的数量可以根据电池包的应用和容量进行调节。In some embodiments, the above-mentioned secondary batteries can also be assembled into a battery pack, and the number of secondary batteries contained in the battery pack can be adjusted according to the application and capacity of the battery pack.
图5是作为一个示例的电池包1。在电池包1中可以包括电池箱和设置于电池箱中 的多个二次电池4。电池箱包括上箱体2和下箱体3，上箱体2能够盖设于下箱体3，并形成用于容纳二次电池4的封闭空间。多个二次电池4可以按照任意的方式排布于电池箱中。FIG. 5 is a battery pack 1 as an example. The battery pack 1 may include a battery box and a plurality of secondary batteries 4 provided in the battery box. The battery box includes an upper box 2 and a lower box 3 . The upper box 2 can be covered with the lower box 3 and form a closed space for accommodating the secondary battery 4 . The plurality of secondary batteries 4 can be arranged in the battery box in any manner.
用电装置Electrical device
本申请还提供一种用电装置，所述用电装置包括所述的二次电池或电池包中的至少一种。所述二次电池或电池包可以用作所述装置的电源，也可以作为所述装置的能量存储单元。所述装置可以但不限于是移动设备(例如手机、笔记本电脑等)、电动车辆(例如纯电动车、混合动力电动车、插电式混合动力电动车、电动自行车、电动踏板车、电动高尔夫球车、电动卡车等)、电气列车、船舶及卫星、储能***等。The present application also provides an electrical device, which includes at least one of the secondary battery or battery pack. The secondary battery or battery pack may be used as a power source for the device or as an energy storage unit for the device. The device may be, but is not limited to, a mobile device (such as a mobile phone, a laptop, etc.), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, or an electric golf ball). vehicles, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.
所述装置可以根据其使用需求来选择二次电池或电池包。The device can select secondary batteries or battery packs according to its usage requirements.
图6是作为一个示例的用电装置5。该用电装置5为纯电动车、混合动力电动车、或插电式混合动力电动车等。为了满足该装置对二次电池的高功率和高能量密度的需求，可以采用电池包。FIG. 6 shows an electrical device 5 as an example. The electric device 5 is a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, or the like. In order to meet the device's requirements for high power and high energy density of secondary batteries, a battery pack can be used.
作为另一个示例的装置可以是手机、平板电脑、笔记本电脑等。该装置通常要求轻薄化，可以采用二次电池作为电源。As another example, the device may be a mobile phone, a tablet, a laptop, etc. The device is usually required to be thin and light, and a secondary battery can be used as a power source.
以下结合实施例进一步说明本申请的有益效果。The beneficial effects of the present application will be further described below in conjunction with the examples.
实施例Example
为了使本申请所解决的技术问题、技术方案及有益效果更加清楚，以下将结合实施例和附图进行进一步详细说明。显然，所描述的实施例仅仅是本申请一部分实施例，而不是全部的实施例。以下对至少一个示例性实施例的描述实际上仅仅是说明性的，决不作为对本申请及其应用的任何限制。基于本申请中的实施例，本领域普通技术人员在没有付出创造性劳动前提下所获得的所有其他实施例都属于本申请保护的范围。本申请的实施例和对比例中所用的材料均可以通过商购获得。In order to make the technical problems, technical solutions and beneficial effects solved by this application clearer, further detailed descriptions will be given below with reference to the embodiments and drawings. Obviously, the described embodiments are only some of the embodiments of the present application, but not all of the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the present application and its applications. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of this application. The materials used in the examples and comparative examples of the present application are all commercially available.
一、负极极片的制备1. Preparation of negative electrode pieces
实施例1Example 1
将人造石墨(作为碳基活性材料)、单壁碳纳米管(作为第二导电剂)、导电剂乙炔黑(作为第一导电剂)、增稠剂羧甲基纤维素钠(CMC)、粘结剂丁苯橡胶(SBR)按照重量比为96.25：0.15：1：1.2：1.4进行混合，加入溶剂去离子水，在真空搅拌机 作用下搅拌至体系2均已状，将其均匀涂覆在厚度为8μm的负极集流体铜箔的两个表面上，在110℃干燥20min，干燥后将极片冷压，分切得到长735mm、膜宽为93mm的负极极片，极片面密度为12mg/cm 2，压实密度为1.6g/cm 3，极片双面总厚度为158μm。 Combine artificial graphite (as a carbon-based active material), single-walled carbon nanotubes (as the second conductive agent), conductive agent acetylene black (as the first conductive agent), thickener sodium carboxymethylcellulose (CMC), viscose The binder styrene-butadiene rubber (SBR) is mixed according to the weight ratio of 96.25:0.15:1:1.2:1.4, add solvent deionized water, stir under the action of a vacuum mixer until the system 2 is uniform, and evenly coat it on the thickness of Dry the two surfaces of the 8 μm negative electrode current collector copper foil at 110°C for 20 minutes. After drying, the electrode pieces are cold pressed and cut into negative electrode pieces with a length of 735mm and a film width of 93mm. The area density of the electrode pieces is 12 mg/cm. 2 , the compacted density is 1.6g/cm 3 , and the total thickness of both sides of the pole piece is 158μm.
实施例2-8Example 2-8
实施例2-8中负极极片的制备方法和实施例1中负极极片的制备方法基本相似，区别主要在于：制备负极极片时，采用的第一导电剂的种类和/或用量、第二导电剂的种类和/或用量、负极活性物质层的厚度、负极活性物质层中碳基材料和硅基材料的质量比中的至少一项不同，具体详见表1。The preparation method of the negative electrode piece in Examples 2-8 is basically similar to the preparation method of the negative electrode piece in Example 1. The main difference lies in: the type and/or amount of the first conductive agent used when preparing the negative electrode piece, and the amount of the first conductive agent. At least one of the type and/or amount of the conductive agent, the thickness of the negative active material layer, and the mass ratio of the carbon-based material and the silicon-based material in the negative active material layer is different. See Table 1 for details.
实施例2-8中负极极片的制备方法和实施例1中负极极片的制备方法还包括以下区别：制备负极极片时负极活性材料、导电剂及其他助剂的质量比和极片面密度中的至少一项不同。The preparation method of the negative electrode piece in Examples 2-8 and the preparation method of the negative electrode piece in Example 1 also include the following differences: the mass ratio of the negative active material, conductive agent and other auxiliaries and the area density of the electrode piece when preparing the negative electrode piece At least one of them is different.
具体地，实施例2中负极活性材料、单壁碳纳米管(作为第二导电剂)、导电剂乙炔黑(作为第一导电剂)、增稠剂羧甲基纤维素钠(CMC)、粘结剂丁苯橡胶(SBR)按质量比为95.795:0.005:1:1.2:2进行混合；极片面密度为8.18mg/cm 2。 Specifically, in Example 2, the negative active material, single-walled carbon nanotubes (as the second conductive agent), the conductive agent acetylene black (as the first conductive agent), the thickener sodium carboxymethyl cellulose (CMC), and the viscose The binder styrene-butadiene rubber (SBR) is mixed according to the mass ratio of 95.795:0.005:1:1.2:2; the polar sheet density is 8.18 mg/cm 2 .
实施例3中负极活性材料、单壁碳纳米管(作为第二导电剂)、导电剂乙炔黑(作为第一导电剂)、增稠剂羧甲基纤维素钠(CMC)、粘结剂丁苯橡胶(SBR)按质量比为94.75:1.05:1:1.2:2进行混合；极片面密度为8.26mg/cm 2。 In Example 3, the negative electrode active material, single-walled carbon nanotubes (as the second conductive agent), the conductive agent acetylene black (as the first conductive agent), the thickener sodium carboxymethyl cellulose (CMC), and the binder D Styrene rubber (SBR) is mixed according to the mass ratio of 94.75:1.05:1:1.2:2; the polar sheet density is 8.26 mg/cm 2 .
实施例4中负极活性材料、单壁碳纳米管(作为第二导电剂)、导电剂乙炔黑(作为第一导电剂)、增稠剂羧甲基纤维素钠(CMC)、粘结剂丁苯橡胶(SBR)按质量比为92.56:3.24:1:1.2:2进行混合；极片面密度为8.44mg/cm 2。 In Example 4, the negative electrode active material, single-walled carbon nanotubes (as the second conductive agent), conductive agent acetylene black (as the first conductive agent), thickener sodium carboxymethyl cellulose (CMC), and binder styrene butadiene rubber (SBR) were mixed at a mass ratio of 92.56:3.24:1:1.2:2; the electrode sheet surface density was 8.44 mg/cm 2 .
实施例5中负极活性材料、单壁碳纳米管(作为第二导电剂)、纳米银线(作为第一导电剂)、增稠剂羧甲基纤维素钠(CMC)、粘结剂丁苯橡胶(SBR)按质量比为94.76:1.04:1:1.2:2进行混合；极片面密度为8.44mg/cm 2。 In Example 5, the negative electrode active material, single-walled carbon nanotubes (as the second conductive agent), nanosilver wires (as the first conductive agent), thickener sodium carboxymethyl cellulose (CMC), and binder butyl styrene The rubber (SBR) is mixed according to the mass ratio of 94.76:1.04:1:1.2:2; the polar sheet density is 8.44mg/cm 2 .
实施例6中负极活性材料、单壁碳纳米管(作为第二导电剂)、纳米银线(作为第一导电剂)、增稠剂羧甲基纤维素钠(CMC)、粘结剂丁苯橡胶(SBR)按质量比为94.88:0.92:1:1.2:2进行混合；极片面密度为8.44mg/cm 2。 In Example 6, the negative active material, single-walled carbon nanotubes (as the second conductive agent), nanosilver wires (as the first conductive agent), thickener sodium carboxymethyl cellulose (CMC), and binder butyl styrene The rubber (SBR) is mixed according to the mass ratio of 94.88:0.92:1:1.2:2; the polar sheet density is 8.44mg/cm 2 .
实施例7中负极活性材料、单壁碳纳米管(作为第二导电剂)、导电剂乙炔黑(作为第一导电剂)、增稠剂羧甲基纤维素钠(CMC)、粘结剂丁苯橡胶(SBR)按质量比为90.3:5.5:1:1.2:2进行混合；极片面密度为8.63mg/cm 2。 In Example 7, the negative electrode active material, single-walled carbon nanotubes (as the second conductive agent), the conductive agent acetylene black (as the first conductive agent), the thickener sodium carboxymethyl cellulose (CMC), and the binder D Styrene rubber (SBR) is mixed according to the mass ratio of 90.3:5.5:1:1.2:2; the polar sheet density is 8.63 mg/cm 2 .
实施例8中负极活性材料、单壁碳纳米管(作为第二导电剂)、导电剂乙炔黑(作为第一导电剂)、增稠剂羧甲基纤维素钠(CMC)、粘结剂丁苯橡胶(SBR)按质量比为95.275:0.525:1:1.2:2进行混合；极片面密度为8.28mg/cm 2。 In Example 8, the negative active material, single-walled carbon nanotubes (as the second conductive agent), the conductive agent acetylene black (as the first conductive agent), the thickener sodium carboxymethyl cellulose (CMC), and the binder D Styrene rubber (SBR) is mixed according to the mass ratio of 95.275:0.525:1:1.2:2; the pole sheet density is 8.28 mg/cm 2 .
实施例9Example 9
第一负极浆料的制备：将负极活性材料、单壁碳纳米管(作为第二导电剂)、导电剂乙炔黑(作为第一导电剂)、增稠剂羧甲基纤维素钠(CMC)、粘结剂丁苯橡胶(SBR)按质量比为95.745:0.055:1:1.2:2进行混合，加入溶剂去离子水，在真空搅拌机作用下搅拌至体系呈均一状；Preparation of the first negative electrode slurry: combine the negative active material, single-walled carbon nanotubes (as the second conductive agent), the conductive agent acetylene black (as the first conductive agent), and the thickener sodium carboxymethylcellulose (CMC) , the binder styrene-butadiene rubber (SBR) is mixed according to the mass ratio of 95.745:0.055:1:1.2:2, add the solvent deionized water, and stir under the action of a vacuum mixer until the system is uniform;
第二负极浆料的制备：将负极活性材料、单壁碳纳米管(作为第二导电剂)、导电剂乙炔黑(作为第一导电剂)、增稠剂羧甲基纤维素钠(CMC)、粘结剂丁苯橡胶(SBR)按质量比为95.5:0.3:1:1.2:2进行混合，加入溶剂去离子水，在真空搅拌机作用下搅拌至体系呈均一状；Preparation of the second negative electrode slurry: combine the negative active material, single-walled carbon nanotubes (as the second conductive agent), the conductive agent acetylene black (as the first conductive agent), and the thickener sodium carboxymethyl cellulose (CMC) , the binder styrene-butadiene rubber (SBR) is mixed according to the mass ratio of 95.5:0.3:1:1.2:2, add the solvent deionized water, and stir under the action of a vacuum mixer until the system is uniform;
将第一负极浆料、第二负极浆料依次按4.22mg/cm 2、6.62mg/cm 2均匀涂覆在厚度为8μm的负极集流体铜箔的两个表面上，在110℃干燥20min，干燥后将极片冷压，分切得到长735mm、膜宽为93mm的负极极片，极片面密度为10.84mg/cm 2，压实密度为1.6g/cm 3，极片双面总厚度为144μm。 The first negative electrode slurry and the second negative electrode slurry are evenly coated on both surfaces of the negative electrode current collector copper foil with a thickness of 8 μm at 4.22 mg/cm 2 and 6.62 mg/cm 2 in sequence, and dried at 110°C for 20 minutes. After drying, the pole pieces were cold-pressed and cut to obtain negative electrode pole pieces with a length of 735mm and a film width of 93mm. The surface density of the pole piece was 10.84mg/cm 2 and the compacted density was 1.6g/cm 3 . The total thickness of both sides of the pole piece was 144μm.
实施例10-11Example 10-11
实施例10-11中负极极片的制备方法和实施例9中负极极片的制备方法基本相似，区别主要在于：制备负极极片时，第一负极活性物质层中采用的第一导电剂的种类和/或用量、第一负极活性物质层中第二导电剂的种类和/或用量、第一负极活性物质层的厚度及第一负极活性物质层中碳基材料和硅基材料的质量比中的至少一项不同，具体详见表2。The preparation method of the negative electrode piece in Examples 10-11 is basically similar to the preparation method of the negative electrode piece in Example 9. The main difference lies in: when preparing the negative electrode piece, the first conductive agent used in the first negative active material layer is The type and/or amount, the type and/or amount of the second conductive agent in the first negative active material layer, the thickness of the first negative active material layer, and the mass ratio of the carbon-based material and the silicon-based material in the first negative active material layer At least one of them is different, see Table 2 for details.
实施例10-11中负极极片的制备方法和实施例9中负极极片的制备方法还包括以下区别：制备负极极片时第一负极活性物质层中负极活性材料、导电剂及其他助剂的质量比和极片面密度中的至少一项不同。The preparation method of the negative electrode sheet in Examples 10-11 and the preparation method of the negative electrode sheet in Example 9 also include the following differences: when preparing the negative electrode sheet, the negative active material, conductive agent and other auxiliary agents in the first negative active material layer At least one of the mass ratio and the polar area density is different.
具体地，实施例10中第一负极浆料制备时，负极活性材料、单壁碳纳米管(作为第二导电剂)、导电剂乙炔黑(作为第一导电剂)、增稠剂羧甲基纤维素钠(CMC)、粘结剂丁苯橡胶(SBR)按质量比为94.8:1:1:1.2:2进行混合。Specifically, when preparing the first negative electrode slurry in Example 10, the negative electrode active material, single-walled carbon nanotubes (as the second conductive agent), the conductive agent acetylene black (as the first conductive agent), and the thickener carboxymethyl Sodium cellulose (CMC) and binder styrene-butadiene rubber (SBR) are mixed at a mass ratio of 94.8:1:1:1.2:2.
将第一负极浆料、第二负极浆料依次按3.25mg/cm 2、6.62mg/cm 2均匀涂覆在厚度 为8μm的负极集流体铜箔的两个表面上，在110℃干燥20min，干燥后将极片冷压，分切得到长735mm、膜宽为93mm的负极极片，极片面密度为9.87mg/cm 2，压实密度为1.6g/cm 3，极片双面总厚度为133μm。 The first negative electrode slurry and the second negative electrode slurry are evenly coated on both surfaces of the negative electrode current collector copper foil with a thickness of 8 μm at 3.25 mg/cm 2 and 6.62 mg/cm 2 in sequence, and dried at 110°C for 20 minutes. After drying, the pole pieces are cold-pressed and cut to obtain negative electrode pole pieces with a length of 735mm and a film width of 93mm. The surface density of the pole piece is 9.87mg/cm 2 , the compacted density is 1.6g/cm 3 , and the total thickness of both sides of the pole piece is 133μm.
实施例11中第一负极浆料制备时，负极活性材料、单壁碳纳米管(作为第二导电剂)、导电剂乙炔黑(作为第一导电剂)、增稠剂羧甲基纤维素钠(CMC)、粘结剂丁苯橡胶(SBR)按质量比为94.384:1.416:1:1.2:2进行混合。When preparing the first negative electrode slurry in Example 11, the negative electrode active material, single-walled carbon nanotubes (as the second conductive agent), the conductive agent acetylene black (as the first conductive agent), and the thickener sodium carboxymethylcellulose (CMC) and binder styrene-butadiene rubber (SBR) are mixed at a mass ratio of 94.384:1.416:1:1.2:2.
将第一负极浆料、第二负极浆料依次按2.79mg/cm 2、6.62mg/cm 2均匀涂覆在厚度为8μm的负极集流体铜箔的两个表面上，在110℃干燥20min，干燥后将极片冷压，分切得到长735mm、膜宽为93mm的负极极片，极片面密度为9.52mg/cm 2，压实密度为1.6g/cm 3，极片双面总厚度为126μm。 The first negative electrode slurry and the second negative electrode slurry are evenly coated on both surfaces of the negative electrode current collector copper foil with a thickness of 8 μm at 2.79 mg/cm 2 and 6.62 mg/cm 2 in sequence, and dried at 110°C for 20 minutes. After drying, the pole pieces are cold-pressed and cut to obtain negative electrode pole pieces with a length of 735mm and a film width of 93mm. The surface density of the pole piece is 9.52mg/cm 2 , the compacted density is 1.6g/cm 3 , and the total thickness of both sides of the pole piece is 126μm.
实施例12-14Examples 12-14
实施例12-14中负极极片的制备方法和实施例10中负极极片的制备方法基本相似，区别主要在于：制备负极极片时，第二负极活性物质层中采用的第一导电剂的种类和/或用量、第二负极活性物质层中第二导电剂的种类和/或用量、第二负极活性物质层的厚度及第二负极活性物质层中碳基材料和硅基材料的质量比中的至少一项不同，具体详见表2。The preparation method of the negative electrode piece in Examples 12-14 is basically similar to the preparation method of the negative electrode piece in Example 10. The main difference lies in: when preparing the negative electrode piece, the amount of the first conductive agent used in the second negative electrode active material layer is The type and/or amount, the type and/or amount of the second conductive agent in the second negative electrode active material layer, the thickness of the second negative electrode active material layer, and the mass ratio of the carbon-based material and the silicon-based material in the second negative electrode active material layer At least one of them is different, see Table 2 for details.
实施例12-14中负极极片的制备方法和实施例10中负极极片的制备方法还包括以下区别：制备负极极片时第二负极活性物质层中负极活性材料、导电剂及其他助剂的质量比和极片面密度中的至少一项不同。The preparation method of the negative electrode sheet in Examples 12-14 and the preparation method of the negative electrode sheet in Example 10 also include the following differences: when preparing the negative electrode sheet, the negative active material, conductive agent and other auxiliary agents in the second negative active material layer At least one of the mass ratio and the polar area density is different.
实施例12中第二负极浆料制备时，负极活性材料、导电剂乙炔黑(作为第一导电剂)、增稠剂羧甲基纤维素钠(CMC)、粘结剂丁苯橡胶(SBR)按质量比为95.8:1:1.2:2进行混合。When preparing the second negative electrode slurry in Example 12, the negative electrode active material, conductive agent acetylene black (as the first conductive agent), thickener sodium carboxymethylcellulose (CMC), and binder styrene-butadiene rubber (SBR) Mix according to the mass ratio of 95.8:1:1.2:2.
将第一负极浆料、第二负极浆料依次按3.25mg/cm 2、7.08mg/cm 2均匀涂覆在厚度为8μm的负极集流体铜箔的两个表面上，在110℃干燥20min，干燥后将极片冷压，分切得到长735mm、膜宽为93mm的负极极片，极片面密度为10.33mg/cm 2，压实密度为1.6g/cm 3，极片双面总厚度为138μm。 The first negative electrode slurry and the second negative electrode slurry are evenly coated on both surfaces of the negative electrode current collector copper foil with a thickness of 8 μm at 3.25 mg/cm 2 and 7.08 mg/cm 2 in sequence, and dried at 110°C for 20 minutes. After drying, the pole pieces are cold-pressed and cut to obtain negative electrode pole pieces with a length of 735mm and a film width of 93mm. The surface density of the pole piece is 10.33mg/cm 2 , the compacted density is 1.6g/cm 3 , and the total thickness of both sides of the pole piece is 138μm.
实施例13中第二负极浆料制备时，负极活性材料、单壁碳纳米管(作为第二导电剂)、导电剂乙炔黑(作为第一导电剂)、增稠剂羧甲基纤维素钠(CMC)、粘结剂丁苯橡胶(SBR)按质量比为95.5:0.3:1:1.2:2进行混合。When preparing the second negative electrode slurry in Example 13, the negative electrode active material, single-walled carbon nanotubes (as the second conductive agent), the conductive agent acetylene black (as the first conductive agent), and the thickener sodium carboxymethylcellulose (CMC) and binder styrene-butadiene rubber (SBR) are mixed at a mass ratio of 95.5:0.3:1:1.2:2.
将第一负极浆料、第二负极浆料依次按3.25mg/cm 2、6.1mg/cm 2均匀涂覆在厚度为8μm的负极集流体铜箔的两个表面上，在110℃干燥20min，干燥后将极片冷压，分切得到长735mm、膜宽为93mm的负极极片，极片面密度为9.35mg/cm 2，压实密度为1.6g/cm 3，极片双面总厚度为126μm。 The first negative electrode slurry and the second negative electrode slurry are evenly coated on both surfaces of the negative electrode current collector copper foil with a thickness of 8 μm at 3.25 mg/cm 2 and 6.1 mg/cm 2 in sequence, and dried at 110°C for 20 minutes. After drying, the pole pieces are cold-pressed and cut to obtain negative electrode pole pieces with a length of 735mm and a film width of 93mm. The surface density of the pole piece is 9.35mg/cm 2 , the compacted density is 1.6g/cm 3 , and the total thickness of both sides of the pole piece is 126μm.
实施例14中第二负极浆料制备时，负极活性材料、单壁碳纳米管(作为第二导电剂)、导电剂乙炔黑(作为第一导电剂)、增稠剂羧甲基纤维素钠(CMC)、粘结剂丁苯橡胶(SBR)按质量比为95.3:0.5:1:1.2:2进行混合。When preparing the second negative electrode slurry in Example 14, the negative electrode active material, single-walled carbon nanotubes (as the second conductive agent), the conductive agent acetylene black (as the first conductive agent), and the thickener sodium carboxymethylcellulose (CMC) and binder styrene-butadiene rubber (SBR) are mixed at a mass ratio of 95.3:0.5:1:1.2:2.
将第一负极浆料、第二负极浆料依次按3.25mg/cm 2、5.4mg/cm 2均匀涂覆在厚度为8μm的负极集流体铜箔的两个表面上，在110℃干燥20min，干燥后将极片冷压，分切得到长735mm、膜宽为93mm的负极极片，极片面密度为8.65mg/cm 2，压实密度为1.6g/cm 3，极片双面总厚度为117μm。 The first negative electrode slurry and the second negative electrode slurry are evenly coated on both surfaces of the negative electrode current collector copper foil with a thickness of 8 μm at 3.25 mg/cm 2 and 5.4 mg/cm 2 in sequence, and dried at 110°C for 20 minutes. After drying, the pole pieces are cold-pressed and cut to obtain negative electrode pole pieces with a length of 735mm and a film width of 93mm. The surface density of the pole piece is 8.65mg/cm 2 and the compacted density is 1.6g/cm 3 . The total thickness of both sides of the pole piece is 117μm.
实施例15Example 15
实施例15和实施例14的区别在于：实施例14中的第一负极活性物质层和实施例15中的第二负极活性物质层相同，实施例14中的第二负极活性物质层和实施例15中的第一负极活性物质层相同。The difference between Example 15 and Example 14 is that: the first negative active material layer in Example 14 is the same as the second negative active material layer in Example 15, and the second negative active material layer in Example 14 is the same as that in Example 14. The first negative active material layer in 15 is the same.
具体地，第一负极浆料的制备：将负极活性材料、单壁碳纳米管(作为第二导电剂)、导电剂乙炔黑(作为第一导电剂)、增稠剂羧甲基纤维素钠(CMC)、粘结剂丁苯橡胶(SBR)按质量比为95.3:0.5:1:1.2:2进行混合，加入溶剂去离子水，在真空搅拌机作用下搅拌至体系呈均一状；Specifically, the preparation of the first negative electrode slurry: the negative electrode active material, single-walled carbon nanotubes (as the second conductive agent), the conductive agent acetylene black (as the first conductive agent), and the thickener sodium carboxymethylcellulose (CMC) and binder styrene-butadiene rubber (SBR) are mixed at a mass ratio of 95.3:0.5:1:1.2:2, add solvent deionized water, and stir under the action of a vacuum mixer until the system is uniform;
第二负极浆料的制备：将负极活性材料、单壁碳纳米管(作为第二导电剂)、导电剂乙炔黑(作为第一导电剂)、增稠剂羧甲基纤维素钠(CMC)、粘结剂丁苯橡胶(SBR)按质量比为94.8:1:1:1.2:2进行混合，加入溶剂去离子水，在真空搅拌机作用下搅拌至体系呈均一状；Preparation of the second negative electrode slurry: combine the negative active material, single-walled carbon nanotubes (as the second conductive agent), the conductive agent acetylene black (as the first conductive agent), and the thickener sodium carboxymethylcellulose (CMC) , the binder styrene-butadiene rubber (SBR) is mixed at a mass ratio of 94.8:1:1:1.2:2, add solvent deionized water, and stir under the action of a vacuum mixer until the system is uniform;
将第一负极浆料、第二负极浆料依次按5.4mg/cm 2、3.25mg/cm 2均匀涂覆在厚度为8μm的负极集流体铜箔的两个表面上，在110℃干燥20min，干燥后将极片冷压，分切得到长735mm、膜宽为93mm的负极极片，极片面密度为8.65mg/cm 2，压实密度为1.6g/cm 3，极片双面总厚度为117μm。 The first negative electrode slurry and the second negative electrode slurry are evenly coated on both surfaces of the negative electrode current collector copper foil with a thickness of 8 μm at 5.4 mg/cm 2 and 3.25 mg/cm 2 in sequence, and dried at 110°C for 20 minutes. After drying, the pole pieces are cold-pressed and cut to obtain negative electrode pole pieces with a length of 735mm and a film width of 93mm. The surface density of the pole piece is 8.65mg/cm 2 and the compacted density is 1.6g/cm 3 . The total thickness of both sides of the pole piece is 117μm.
实施例16Example 16
第一负极浆料的制备：将负极活性材料、多壁碳纳米管(作为第二导电剂)、导电 剂科琴黑(作为第一导电剂)、增稠剂羧甲基纤维素钠(CMC)、粘结剂丁苯橡胶(SBR)按质量比为94.8:1:1:1.2:2进行混合，加入溶剂去离子水，在真空搅拌机作用下搅拌至体系呈均一状；Preparation of the first negative electrode slurry: add the negative active material, multi-walled carbon nanotubes (as the second conductive agent), the conductive agent Ketjen Black (as the first conductive agent), and the thickener sodium carboxymethylcellulose (CMC ) and the binder styrene-butadiene rubber (SBR) are mixed at a mass ratio of 94.8:1:1:1.2:2, add solvent deionized water, and stir under the action of a vacuum mixer until the system is uniform;
第二负极浆料的制备：将负极活性材料、多壁碳纳米管(作为第二导电剂)、导电剂碳黑(作为第一导电剂)、增稠剂羧甲基纤维素钠(CMC)、粘结剂丁苯橡胶(SBR)按质量比为95.3:0.5:1:1.2:2进行混合，加入溶剂去离子水，在真空搅拌机作用下搅拌至体系呈均一状；Preparation of the second negative electrode slurry: combine the negative active material, multi-walled carbon nanotubes (as the second conductive agent), the conductive agent carbon black (as the first conductive agent), and the thickener sodium carboxymethylcellulose (CMC) , the binder styrene-butadiene rubber (SBR) is mixed according to the mass ratio of 95.3:0.5:1:1.2:2, add the solvent deionized water, and stir under the action of a vacuum mixer until the system is uniform;
将第一负极浆料、第二负极浆料依次按3.25mg/cm 2、5.4mg/cm 2均匀涂覆在厚度为8μm的负极集流体铜箔的两个表面上，在110℃干燥20min，干燥后将极片冷压，分切得到长735mm、膜宽为93mm的负极极片，极片面密度为8.65mg/cm 2，压实密度为0.705g/cm 3，极片双面总厚度为253μm。 The first negative electrode slurry and the second negative electrode slurry are evenly coated on both surfaces of the negative electrode current collector copper foil with a thickness of 8 μm at 3.25 mg/cm 2 and 5.4 mg/cm 2 in sequence, and dried at 110°C for 20 minutes. After drying, the pole pieces are cold-pressed and cut to obtain negative electrode pole pieces with a length of 735mm and a film width of 93mm. The surface density of the pole piece is 8.65mg/cm 2 and the compacted density is 0.705g/cm 3 . The total thickness of both sides of the pole piece is 253μm.
实施例17Example 17
实施例17和实施例2的区别在于：实施例17中负极活性材料、单壁碳纳米管(作为第二导电剂)、导电剂乙炔黑(作为第一导电剂)、增稠剂羧甲基纤维素钠(CMC)、粘结剂丁苯橡胶(SBR)按质量比为94.2:1.6:1:1.2:2进行混合；极片面密度为6.8mg/cm 2。 The difference between Example 17 and Example 2 is that in Example 17, the negative active material, single-walled carbon nanotubes (as the second conductive agent), the conductive agent acetylene black (as the first conductive agent), and the thickener carboxymethyl Sodium cellulose (CMC) and binder styrene-butadiene rubber (SBR) are mixed at a mass ratio of 94.2:1.6:1:1.2:2; the pole sheet density is 6.8 mg/cm 2 .
对比例1Comparative example 1
对比例1中负极极片的制备方法和实施例1中负极极片的制备方法基本相似，区别在于：仅包括第一导电剂，采用相同质量的负极活性材料代替第二导电剂，具体详见表1。The preparation method of the negative electrode piece in Comparative Example 1 is basically similar to the preparation method of the negative electrode piece in Example 1. The difference is that only the first conductive agent is included, and the negative active material of the same quality is used instead of the second conductive agent. For details, see Table 1.
对比例2Comparative example 2
对比例2中负极极片的制备方法和实施例2中负极极片的制备方法基本相似，区别在于：仅包括第一导电剂，采用相同质量的负极活性材料代替第二导电剂，具体详见表1。The preparation method of the negative electrode piece in Comparative Example 2 is basically similar to the preparation method of the negative electrode piece in Example 2. The difference is that only the first conductive agent is included, and the negative active material of the same quality is used instead of the second conductive agent. For details, see Table 1.
对比例3Comparative example 3
对比例3中负极极片的制备方法和实施例9中负极极片的区别在于：第一负极活性物质层中仅包括第一导电剂，采用相同质量的负极活性材料代替第二导电剂；第一负极活性物质层中仅包括第一导电剂，采用相同质量的负极活性材料代替第二导电剂，具体详见表2。The difference between the preparation method of the negative electrode sheet in Comparative Example 3 and the negative electrode sheet in Example 9 is that: the first negative active material layer only includes the first conductive agent, and the negative active material of the same quality is used instead of the second conductive agent; A negative active material layer only includes the first conductive agent, and the negative active material of the same quality is used to replace the second conductive agent. See Table 2 for details.
对比例4Comparative example 4
对比例4中负极极片的制备方法和实施例10中负极极片的区别在于：第一负极活性物质层中仅包括第一导电剂，采用相同质量的负极活性材料代替第二导电剂；第一负极活性物质层中仅包括第一导电剂，采用相同质量的负极活性材料代替第二导电剂，具体详见表2。The difference between the preparation method of the negative electrode sheet in Comparative Example 4 and the negative electrode sheet in Example 10 is that: the first negative active material layer only includes the first conductive agent, and the negative active material of the same quality is used instead of the second conductive agent; A negative active material layer only includes the first conductive agent, and the negative active material of the same quality is used to replace the second conductive agent. See Table 2 for details.
对比例5Comparative example 5
对比例5中负极极片的制备方法和实施例11中负极极片的区别在于：第一负极活性物质层中仅包括第一导电剂，采用相同质量的负极活性材料代替第二导电剂；第一负极活性物质层中仅包括第一导电剂，采用相同质量的负极活性材料代替第二导电剂，具体详见表2。The difference between the preparation method of the negative electrode sheet in Comparative Example 5 and the negative electrode sheet in Example 11 is that: the first negative active material layer only includes the first conductive agent, and the negative active material of the same quality is used instead of the second conductive agent; A negative active material layer only includes the first conductive agent, and the negative active material of the same quality is used to replace the second conductive agent. See Table 2 for details.
对比例6Comparative example 6
对比例6中负极极片的制备方法和实施例12中负极极片的区别在于：第一负极活性物质层中仅包括第一导电剂，采用相同质量的负极活性材料代替第二导电剂；第一负极活性物质层中仅包括第一导电剂，采用相同质量的负极活性材料代替第二导电剂，具体详见表2。The difference between the preparation method of the negative electrode sheet in Comparative Example 6 and the negative electrode sheet in Example 12 is that: the first negative active material layer only includes the first conductive agent, and the negative active material of the same quality is used instead of the second conductive agent; A negative active material layer only includes the first conductive agent, and the negative active material of the same quality is used to replace the second conductive agent. See Table 2 for details.
对比例7Comparative example 7
对比例7中负极极片的制备方法和实施例13中负极极片的区别在于：第一负极活性物质层中仅包括第一导电剂，采用相同质量的负极活性材料代替第二导电剂；第一负极活性物质层中仅包括第一导电剂，采用相同质量的负极活性材料代替第二导电剂，具体详见表2。The difference between the preparation method of the negative electrode sheet in Comparative Example 7 and the negative electrode sheet in Example 13 is that: the first negative active material layer only includes the first conductive agent, and the negative active material of the same quality is used instead of the second conductive agent; A negative active material layer only includes the first conductive agent, and the negative active material of the same quality is used to replace the second conductive agent. See Table 2 for details.
对比例8Comparative example 8
对比例8中负极极片的制备方法和实施例14中负极极片的区别在于：第一负极活性物质层中仅包括第一导电剂，采用相同质量的负极活性材料代替第二导电剂；第一负极活性物质层中仅包括第一导电剂，采用相同质量的负极活性材料代替第二导电剂，具体详见表2。The difference between the preparation method of the negative electrode sheet in Comparative Example 8 and the negative electrode sheet in Example 14 is that: the first negative active material layer only includes the first conductive agent, and the negative active material of the same quality is used instead of the second conductive agent; A negative active material layer only includes the first conductive agent, and the negative active material of the same quality is used to replace the second conductive agent. See Table 2 for details.
需要说明的是，上述各实施例和对比例中，通过调整各负极活性物质层中第一导电剂的种类和/或质量占比、第二导电剂的种类和/或质量占比以及负极活性物质层的厚度可调整活性物质层的导通因子，具体详见表1或表2。实施例1-8、实施例17和对比例1-2的负极极片的参数如下表1所示。实施例9～16和对比例3～8的负极极片的参数如下表2所示。It should be noted that in the above-mentioned embodiments and comparative examples, by adjusting the type and/or mass proportion of the first conductive agent, the type and/or mass proportion of the second conductive agent, and the negative electrode activity in each negative active material layer The thickness of the material layer can adjust the conduction factor of the active material layer. See Table 1 or Table 2 for details. The parameters of the negative electrode plates of Examples 1-8, 17 and Comparative Examples 1-2 are as shown in Table 1 below. The parameters of the negative electrode pieces of Examples 9 to 16 and Comparative Examples 3 to 8 are as shown in Table 2 below.
表1Table 1
组别Group i 0 i 0 r 1 r 1 n 01 n 01 r 2 r 2 n 02 n 02 L 0(μm) L 0 (μm) m 0 m 0
实施例1Example 1 0.1000.100 乙炔黑1.01Acetylene black 1.01 1％1% SWCNT 5000SWCNT 5000 0.15％0.15% 7575 100:0100:0
实施例2Example 2 0.0050.005 乙炔黑1.01Acetylene black 1.01 1％1% SWCNT 5000SWCNT 5000 0.005％0.005% 51.551.5 85:1585:15
实施例3Example 3 1.0001.000 乙炔黑1.01Acetylene black 1.01 1％1% SWCNT 5000SWCNT 5000 1.05％1.05% 52.552.5 85:1585:15
实施例4Example 4 3.0003.000 乙炔黑1.01Acetylene black 1.01 1％1% SWCNT 5000SWCNT 5000 3.24％3.24% 5454 85:1585:15
实施例5Example 5 1.0001.000 纳米银线200Nano silver wire 200 1％1% SWCNT 5000SWCNT 5000 1.04％1.04% 5454 85:1585:15
实施例6Example 6 1.0001.000 纳米银线800Nano silver wire 800 1％1% SWCNT 5000SWCNT 5000 0.92％0.92% 5454 85:1585:15
实施例7Example 7 1.0001.000 乙炔黑1.01Acetylene black 1.01 1％1% SWCNT 1000SWCNT 1000 5.5％5.5% 5555 85:1585:15
实施例8Example 8 1.0001.000 乙炔黑1.01Acetylene black 1.01 1％1% SWCNT 10000SWCNT 10000 0.525％0.525% 52.552.5 85:1585:15
实施例17Example 17 2.0002.000 乙炔黑1.01Acetylene black 1.01 1％1% SWCNT 5000SWCNT 5000 1.6％1.6% 4040 75:2575:25
对比例1Comparative example 1 0.00010.0001 乙炔黑1.01Acetylene black 1.01 1％1% // // 7575 100:0100:0
对比例2Comparative example 2 0.00020.0002 乙炔黑1.01Acetylene black 1.01 1％1% // // 51.551.5 85:1585:15
表2Table 2
Figure PCTCN2022118684-appb-000001
Figure PCTCN2022118684-appb-000001
Figure PCTCN2022118684-appb-000002
Figure PCTCN2022118684-appb-000002
其中，表1和表2中i 0表示负极活性物质层为单层时负极活性物质层的导通因子，或负极活性物质层为两层时总的负极活性物质层的导通因子；i 总表示负极活性物质层为两层时总的负极活性物质层的导通因子，i 1表示负极活性物质层为两层时第一负极活性物质层的导通因子，i 2表示负极活性物质层为两层时第二负极活性物质层的导通因子。 Among them, i 0 in Table 1 and Table 2 represents the conduction factor of the negative active material layer when the negative active material layer is a single layer, or the conduction factor of the total negative active material layer when the negative active material layer is two layers; i total Indicates the conduction factor of the total negative active material layer when there are two negative active material layers. i 1 indicates the conduction factor of the first negative active material layer when there are two negative active material layers. i 2 indicates that the negative active material layer is The conduction factor of the second negative active material layer when there are two layers.
L 0表示负极活性物质层为单层时负极活性物质层的厚度；L 1表示负极活性物质层为双层时第一负极活性物质层的厚度，L 2表示负极活性物质层为双层时第二负极活性物质层的厚度。 L 0 represents the thickness of the negative electrode active material layer when the negative electrode active material layer is a single layer; L 1 represents the thickness of the first negative electrode active material layer when the negative electrode active material layer is a double layer; L 2 represents the thickness of the first negative electrode active material layer when the negative electrode active material layer is a double layer The thickness of the two negative electrode active material layers.
r 1表示第一导电剂的长径比，r 2表示第二导电剂的长径比。 r1 represents the aspect ratio of the first conductive agent, and r2 represents the aspect ratio of the second conductive agent.
n 01表示负极活性物质层为单层时第一导电剂的质量占比，n 02表示负极活性物质层为单层时第二导电剂的质量占比；n 11表示负极活性物质层为两层时，第一导电剂在第一负极活性物质层中的质量占比，n 12表示负极活性物质层为两层时，第二导电剂在第一负极活性物质层中的质量占比；n 21表示负极活性物质层为两层时，第一导电剂在第二负极活性物质层中的质量占比，n 22表示负极活性物质层为两层时，第二导电剂在第二负极活性物质层中的质量占比。 n 01 indicates the mass proportion of the first conductive agent when the negative active material layer is a single layer; n 02 indicates the mass proportion of the second conductive agent when the negative active material layer is a single layer; n 11 indicates that the negative active material layer is two layers When , the mass proportion of the first conductive agent in the first negative active material layer, n 12 represents the mass proportion of the second conductive agent in the first negative active material layer when the negative active material layer is two layers; n 21 Indicates the mass proportion of the first conductive agent in the second negative electrode active material layer when the negative electrode active material layer is two layers. n 22 indicates the mass proportion of the second conductive agent in the second negative electrode active material layer when the negative electrode active material layer is two layers. The quality ratio in .
m 0表负极活性物质层为单层时，负极活性物质层内碳基活性材料和硅基活性材料的质量比；m 1表示负极活性物质层为两层时，第一负极活性物质层内碳基活性材料和硅基活性材料的质量比；m 2表示负极活性物质层为两层时，第二负极活性物质层内碳基活性材料和硅基活性材料的质量比。 m 0 represents the mass ratio of the carbon-based active material and the silicon-based active material in the negative active material layer when the negative active material layer is a single layer; m 1 represents the carbon-based active material in the first negative active material layer when there are two negative active material layers. The mass ratio of the carbon-based active material and the silicon-based active material; m2 represents the mass ratio of the carbon-based active material and the silicon-based active material in the second negative active material layer when the negative active material layer is two layers.
SWCNT表示单壁碳纳米管，MWCNT表示多壁碳纳米管。SWCNT stands for single-walled carbon nanotube, and MWCNT stands for multi-walled carbon nanotube.
二、电池的制备2. Preparation of batteries
1、正极极片的制备：1. Preparation of positive electrode plate:
将锂镍钴锰氧化物LiNi 0.8Co 0.1Mn 0.1O 2(NCM 811)、导电剂炭黑(Super P)、粘结剂聚偏氟乙烯(PVDF)按重量比97.5∶1.5∶1在适量的N-甲基吡咯烷酮(NMP)中充分搅拌混合均匀，使其形成均匀的正极浆料；将正极浆料涂覆于正极集流体铝箔的表面，经烘干、冷压、分条、裁切，得到正极极片。正极极片的压实密度为3.5g/cm 3，面密度为18.04mg/cm 2。 Add lithium nickel cobalt manganese oxide LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM 811 ), conductive agent carbon black (Super P), and binder polyvinylidene fluoride (PVDF) in an appropriate amount according to the weight ratio of 97.5:1.5:1. N-Methylpyrrolidone (NMP) is thoroughly stirred and mixed evenly to form a uniform positive electrode slurry; the positive electrode slurry is coated on the surface of the positive electrode current collector aluminum foil, dried, cold pressed, slit, and cut. Get the positive electrode piece. The compacted density of the positive electrode piece is 3.5g/cm 3 and the areal density is 18.04mg/cm 2 .
2、隔离膜：以厚度为12μm的聚乙烯膜(PE)作为隔离膜。2. Isolation film: Polyethylene film (PE) with a thickness of 12 μm is used as the isolation film.
3、电解液的制备：将碳酸乙烯酯(EC)、碳酸甲乙酯(EMC)、碳酸二乙酯(DEC)按体积比1:1:1混合，然后将LiPF6均匀溶解在上述溶液中，得到电解液。该电解液中，LiPF 6的浓度为1mol/L。 3. Preparation of electrolyte: Mix ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a volume ratio of 1:1:1, and then dissolve LiPF6 evenly in the above solution. Get electrolyte. In this electrolyte, the concentration of LiPF 6 is 1 mol/L.
4、二次电池的制备：将正极极片、隔离膜、上述各实施例或对比例中的负极极片按顺序堆叠，使隔离膜处于正、负极极片之间起到隔离的作用，然后卷绕得到裸电芯；将裸电芯置于外包装壳中，干燥后注入上述制备的电解液，经真空封装、静置、化成、整形等工序，获得二次电池。4. Preparation of the secondary battery: Stack the positive electrode sheet, the isolation film, and the negative electrode sheet in the above embodiments or comparative examples in order, so that the isolation film plays an isolation role between the positive and negative electrode sheets, and then The bare battery core is obtained by winding; the bare battery core is placed in an outer packaging shell, dried and then injected with the electrolyte prepared above. After vacuum packaging, standing, formation, shaping and other processes, a secondary battery is obtained.
三、电池性能测试3. Battery performance test
1、二次电池的放电DCR测试1. Discharge DCR test of secondary battery
将制作好的各二次电池在25℃环境中执行以下方法：Perform the following methods on each prepared secondary battery in a 25°C environment:
将制作好的各二次电池在45℃下以0.02C倍率充电至3.4V，然后以0.1C倍率充电至3.75V所测的容量标记为C0，然后在25℃下以0.33C倍率充电至4.25V，4.25V恒压充电至0.05C所测得的容量标记为C1，最后以0.33C放电至2.5V所测得的容量标记为D0；静置5min；以0.33D0放电至2.5V；静置5分钟；以0.33D0充电至4.25V，4.25V恒压充电至0.05D0；静置5min；以0.33D0放电90min，此时电芯的电量为满充时的50％，将其称之为50％SOC；静止30min后记录静止电压标记为V0；以4D0放电30s后记录电压V1。其中，50％SOC放电DCR＝(V0-V1)/4D0。Each prepared secondary battery was charged to 3.4V at a rate of 0.02C at 45°C, then charged to 3.75V at a rate of 0.1C. The measured capacity was marked C0, and then charged to 4.25V at a rate of 0.33C at 25°C. V, the capacity measured by charging at 4.25V constant voltage to 0.05C is marked as C1, and finally the capacity measured by discharging to 2.5V at 0.33C is marked as D0; let it stand for 5 minutes; discharge it with 0.33D0 to 2.5V; let it stand 5 minutes; charge to 4.25V at 0.33D0, charge to 0.05D0 at 4.25V constant voltage; let it stand for 5 minutes; discharge at 0.33D0 for 90 minutes. At this time, the battery power is 50% of the full charge, which is called 50 % SOC; record the resting voltage after 30 minutes of rest and mark it as V0; record the voltage V1 after discharging with 4D0 for 30 seconds. Among them, 50% SOC discharge DCR=(V0-V1)/4D0.
2、二次电池的充电DCR测试2. Charging DCR test of secondary battery
将制作好的各二次电池在25℃环境中执行以下方法：Perform the following methods on each prepared secondary battery in a 25°C environment:
将制作好的各二次电池在45℃下以0.02C倍率充电至3.4V，然后以0.1C倍率充电至3.75V所测的容量标记为C0，然后在25℃下以0.33C倍率充电至4.25V，4.25V恒压充电至0.05C所测得的容量标记为C1，最后以0.33C放电至2.5V所测得的容量标记为D0；静置5min；以0.33D0放电至2.5V；静置5分钟；以0.33D0充电至4.25V，4.25V恒压充电至0.05D0；静置5min；以0.33D0放电90min，此时电芯的电量为满充时的50％， 将其称之为50％SOC；静止30min后记录静止电压标记为V2；以4D0充电30s后记录电压V3。其中，50％SOC充电DCR＝(V3-V2)/4D0。Each prepared secondary battery was charged to 3.4V at a rate of 0.02C at 45°C, then charged to 3.75V at a rate of 0.1C. The measured capacity was marked C0, and then charged to 4.25V at a rate of 0.33C at 25°C. V, the capacity measured by charging at 4.25V constant voltage to 0.05C is marked as C1, and finally the capacity measured by discharging to 2.5V at 0.33C is marked as D0; let it stand for 5 minutes; discharge it with 0.33D0 to 2.5V; let it stand 5 minutes; charge to 4.25V at 0.33D0, charge to 0.05D0 at 4.25V constant voltage; let it stand for 5 minutes; discharge at 0.33D0 for 90 minutes. At this time, the battery power is 50% of the full charge, which is called 50 % SOC; record the resting voltage after 30 minutes of rest and mark it as V2; record the voltage V3 after charging with 4D0 for 30 seconds. Among them, 50% SOC charging DCR = (V3-V2)/4D0.
3、二次电池在25℃下的循环性能测试3. Cycle performance test of secondary battery at 25℃
将制作好的各二次电池在45℃的恒温环境下，以1D0倍率恒流充电至电压为4.25V，再在4.25V电压下恒压充电至电流小于等于0.05D0，之后静置5min，然后以1D0倍率恒流放电至电压为2.5V，静置5min，此为一个循环充放电过程，此次的放电容量记为二次电池第1次循环的放电容量。将二次电池按照上述方法进行500个循环充放电测试，循环500圈后的容量保持率＝循环500圈后的容量/第1次循环的放电容量x100％。Charge each prepared secondary battery in a constant temperature environment of 45°C at a constant current of 1D0 until the voltage is 4.25V, then charge at a constant voltage of 4.25V until the current is less than or equal to 0.05D0, then let it stand for 5 minutes, and then Discharge at a constant current of 1D0 rate until the voltage is 2.5V, and let it stand for 5 minutes. This is a cycle charge and discharge process. The discharge capacity this time is recorded as the discharge capacity of the first cycle of the secondary battery. The secondary battery is subjected to 500 cycle charge and discharge tests according to the above method. The capacity retention rate after 500 cycles = the capacity after 500 cycles/the discharge capacity of the first cycle x 100%.
4、二次电池在45℃下的极片循环膨胀性能测试4. Cyclic expansion performance test of secondary battery pole pieces at 45°C
将制作好的负极极片完成冷压工序时的极片厚度记为h0，按上述二次电池在45℃下的循环性能测试方法，将二次电池循环500圈后，以1D0倍率恒流充电至电压为4.25V，再在4.25V电压下恒压充电至电流小于等于0.05D0，之后静置5min，此时电芯为满充状态，然后在干燥房中拆解此电芯，将循环500圈后的负极极片厚度记为h500，则二次电池在45℃下的极片500圈循环膨胀率＝(h500-h0)/h0*100％。Record the thickness of the negative electrode piece when the cold pressing process is completed as h0. According to the above-mentioned cycle performance test method of the secondary battery at 45°C, cycle the secondary battery for 500 cycles and charge it at a constant current rate of 1D0 to a voltage of 4.25V, then charge at a constant voltage of 4.25V until the current is less than or equal to 0.05D0, then let it sit for 5 minutes. At this time, the battery core is fully charged. Then disassemble the battery core in a drying room and cycle 500 The thickness of the negative electrode piece after the cycle is recorded as h500. Then the 500 cycle expansion rate of the electrode piece of the secondary battery at 45°C = (h500-h0)/h0*100%.
各实施例和对比例制得的二次电池的性能测试结果如下表3所示。The performance test results of the secondary batteries prepared in each embodiment and comparative example are shown in Table 3 below.
表3table 3
Figure PCTCN2022118684-appb-000003
Figure PCTCN2022118684-appb-000003
Figure PCTCN2022118684-appb-000004
Figure PCTCN2022118684-appb-000004
由表3中实施例1-8和实施例17的结果可知，对于全部采用碳基活性材料作为负极活性材料的负极极片，或对于采用碳基活性材料和硅基活性材料的混合物作为负极活性材料的负极极片而言，通过调配两种导电剂的长径比及各自在负极活性物质层中的质量占比、负极活性物质层的厚度，使得负极活性物质层的导通因子i 0满足0.005≤i 0≤3时，可增大负极活性物质层中电子移动通路，使得尽可能多的负极活性材料参与充放电过程，提升二次电池的动力学性能、快充性能和循环性能。 It can be seen from the results of Examples 1-8 and 17 in Table 3 that for negative electrode sheets that use all carbon-based active materials as negative electrode active materials, or for use a mixture of carbon-based active materials and silicon-based active materials as negative electrode active materials For the negative electrode piece of the material, by adjusting the aspect ratio of the two conductive agents, their respective mass proportions in the negative active material layer, and the thickness of the negative active material layer, the conduction factor i 0 of the negative active material layer satisfies When 0.005≤i 0 ≤3, the electron movement path in the negative active material layer can be increased, allowing as many negative active materials as possible to participate in the charge and discharge process, and improving the kinetic performance, fast charging performance and cycle performance of the secondary battery.
由实施例9-16的结果可知，通过分别调配各负极活性物质层中两种导电剂的长径比、两种导电剂在各负极活性物质层中的质量占比、两个负极活性物质层的厚度，使得总的负极活性物质层的导通因子i 0满足0.005≤i 0≤3时，可提升二次电池的动力学性能、快充性能和循环性能。 It can be seen from the results of Examples 9-16 that by separately formulating the aspect ratio of the two conductive agents in each negative active material layer, the mass proportion of the two conductive agents in each negative active material layer, the two negative active material layers The thickness makes the conduction factor i 0 of the total negative active material layer satisfy 0.005≤i 0 ≤3, which can improve the kinetic performance, fast charging performance and cycle performance of the secondary battery.
实施例2-4的主要区别在于，通过调整长径比大的第二导电剂的质量占比及负极活性物质层的厚度，以实现对于负极活性物质层的导通因子的调整；由实施例2-4的结果可知，通过增加长径比大的第二导电剂的质量占比，可提高负极活性物质层的导通因子，进而提高二次电池的动力学性能、快充性能和循环性能。The main difference between Examples 2-4 is that by adjusting the mass proportion of the second conductive agent with a large aspect ratio and the thickness of the negative active material layer, the conduction factor of the negative active material layer is adjusted; from the embodiment It can be seen from the results of 2-4 that by increasing the mass proportion of the second conductive agent with a large aspect ratio, the conduction factor of the negative active material layer can be improved, thereby improving the kinetic performance, fast charging performance and cycle performance of the secondary battery. .
实施例14-15的主要区别在于，实施例14中的第一负极活性物质层和实施例15中的第二负极活性物质层相同，实施例14中的第二负极活性物质层和实施例15中的第一负极活性物质层相同；由实施例14和实施例15的结果可知，当负极活性物质层为两层时，在总的负极活性物质层的导通因子满足0.005≤i 0≤3时，将第一负极活性物质层中硅基材料的质量占比设置为大于第二负极活性物质层中硅基材料的质量占比，将第一负极活性物质层的厚度设置为小于第二负极活性物质层的厚度，同时第一负极活性物质层的导通因子满足0.1≤i 1≤6、第二负极活性物质层的导通因子满足0＜i 2≤0.75，可进一步提升二次电池的动力学性能、快充性能和循环性能。 The main difference between Embodiments 14-15 is that the first negative active material layer in Embodiment 14 is the same as the second negative active material layer in Embodiment 15, and the second negative active material layer in Embodiment 14 is the same as that in Embodiment 15. The first negative active material layer in is the same; it can be seen from the results of Example 14 and Example 15 that when the negative active material layer is two layers, the conduction factor of the total negative active material layer satisfies 0.005≤i 0 ≤3 When , the mass proportion of the silicon-based material in the first negative electrode active material layer is set to be greater than the mass proportion of the silicon-based material in the second negative electrode active material layer, and the thickness of the first negative electrode active material layer is set to be smaller than the second negative electrode active material layer. The thickness of the active material layer, while the conduction factor of the first negative active material layer satisfies 0.1≤i 1 ≤6, and the conduction factor of the second negative active material layer satisfies 0<i 2 ≤0.75, can further improve the performance of the secondary battery. Kinetic performance, fast charging performance and cycle performance.
由实施例1和对比例1的结果、实施例2和对比例2的结果、实施例9和对比例3的结果、实施例10和对比例4的结果、实施例11和对比例5的结果、实施例12和对比例6的结果、实施例13和对比例7的结果以及实施例14和对比例8的结果可知，当负极活性物质层中含有长径比大的线状的导电剂时，可提高二次电池的快充性能、循环容量保持率；并降低循环500圈后负极极片的满充膨胀率，尤其当负极活性物质层中含 有硅基活性材料时，负极活性物质层中加入线状的导电剂后负极极片体积膨胀率下降更明显，技术人员分析其原因，这可能是由于线状的导电剂可附着在硅基活性材料的表面，在为硅基活性材料导通电子的同时束缚硅基材料在嵌锂过程中的膨胀。From the results of Example 1 and Comparative Example 1, the results of Example 2 and Comparative Example 2, the results of Example 9 and Comparative Example 3, the results of Example 10 and Comparative Example 4, the results of Example 11 and Comparative Example 5 , the results of Example 12 and Comparative Example 6, the results of Example 13 and Comparative Example 7, and the results of Example 14 and Comparative Example 8, it can be seen that when the negative active material layer contains a linear conductive agent with a large aspect ratio , can improve the fast charging performance and cycle capacity retention rate of secondary batteries; and reduce the full charge expansion rate of the negative electrode sheet after 500 cycles, especially when the negative active material layer contains silicon-based active materials, the negative active material layer After adding the linear conductive agent, the volume expansion rate of the negative electrode plate decreased more significantly. The technician analyzed the reason. This may be because the linear conductive agent can adhere to the surface of the silicon-based active material and conduct conduction for the silicon-based active material. The electrons simultaneously bind the expansion of the silicon-based material during the lithium insertion process.
以上所述，仅为本申请的具体实施方式，但本申请的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本申请揭露的技术范围内，可轻易想到各种等效的修改或替换，这些修改或替换都应涵盖在本申请的保护范围之内。因此，本申请的保护范围应以权利要求的保护范围为准。The above are only specific embodiments of the present application, but the protection scope of the present application is not limited thereto. Any person familiar with the technical field can easily think of various equivalent methods within the technical scope disclosed in the present application. Modification or replacement, these modifications or replacements shall be covered by the protection scope of this application. Therefore, the protection scope of this application should be subject to the protection scope of the claims.

Claims (16)

  1. 一种负极极片，包括：A negative electrode piece, including:
    负极集流体；Negative current collector;
    负极活性物质层，位于所述负极集流体的至少一个表面上，所述负极活性物质层包括长径比不同的第一导电剂和第二导电剂，所述负极活性物质层的导通因子记为i 0，则所述负极活性物质层的导通因子满足：0.005≤i 0≤3； A negative active material layer is located on at least one surface of the negative current collector. The negative active material layer includes a first conductive agent and a second conductive agent with different aspect ratios. The conduction factor of the negative active material layer is expressed as is i 0 , then the conduction factor of the negative active material layer satisfies: 0.005≤i 0 ≤3;
    当所述负极活性物质层为单层时，导通因子i 0＝(第一导电剂长径比*第一导电剂在负极活性物质层的质量占比)/负极活性物质层的总厚度+(第二导电剂长径比*第二导电剂在负极活性物质层的质量占比)/负极活性物质层的总厚度； When the negative active material layer is a single layer, the conduction factor i 0 =(aspect ratio of the first conductive agent*mass proportion of the first conductive agent in the negative active material layer)/total thickness of the negative active material layer+ (Aspect ratio of the second conductive agent*mass proportion of the second conductive agent in the negative active material layer)/total thickness of the negative active material layer;
    当所述负极活性物质层包括第一负极活性物质层和第二负极活性物质层时，导通因子i 0＝((第一负极活性物质层中第一导电剂重量+第二负极活性物质层中第一导电剂的重量)/单位面积负极单面活性物质层的总重量*第一导电剂的长径比+(第一负极活性物质层中第二导电剂重量+第二负极活性物质层中第二导电剂的重量)/单位面积负极单面活性物质层的总重量*第二导电剂的长径比))/活性物资层的总厚度。 When the negative active material layer includes a first negative active material layer and a second negative active material layer, the conduction factor i 0 = ((weight of the first conductive agent in the first negative active material layer + second negative active material layer weight of the first conductive agent in the unit area)/total weight of the active material layer on one side of the negative electrode per unit area*aspect ratio of the first conductive agent+(weight of the second conductive agent in the first negative active material layer+second negative active material layer The weight of the second conductive agent)/the total weight of the active material layer on one side of the negative electrode per unit area*the aspect ratio of the second conductive agent)/the total thickness of the active material layer.
  2. 如权利要求1所述的负极极片，其中所述第一导电剂的长径比记为a，则所述第一导电剂的长径比满足：a＜1000；The negative electrode piece according to claim 1, wherein the aspect ratio of the first conductive agent is denoted as a, then the aspect ratio of the first conductive agent satisfies: a<1000;
    可选地，所述第一导电剂包括炭黑、超导电乙炔黑、科琴黑和纳米银线中的一种或多种。Optionally, the first conductive agent includes one or more of carbon black, superconducting acetylene black, Ketjen black and nanosilver wires.
  3. 如权利要求1至2任一项所述的负极极片，其中所述第二导电剂的长径比记为b，则所述第二导电剂的长径比满足：1000≤b≤10000；The negative electrode piece according to any one of claims 1 to 2, wherein the aspect ratio of the second conductive agent is denoted as b, then the aspect ratio of the second conductive agent satisfies: 1000≤b≤10000;
    可选地，所述第二导电剂包括单壁碳纳米管和多壁碳纳米管中的一种或多种。Optionally, the second conductive agent includes one or more of single-walled carbon nanotubes and multi-walled carbon nanotubes.
  4. 如权利要求1至3任一项所述的负极极片，其中所述负极活性物质层还包括负极活性材料，所述负极活性材料为碳基活性材料或碳基活性材料与硅基活性材料的混合物。The negative electrode sheet according to any one of claims 1 to 3, wherein the negative active material layer further includes a negative active material, and the negative active material is a carbon-based active material or a combination of a carbon-based active material and a silicon-based active material. mixture.
  5. 如权利要求4所述的负极极片，其中所述硅基活性材料包括硅、硅氧材料和硅碳材料中的一种或多种。The negative electrode sheet of claim 4, wherein the silicon-based active material includes one or more of silicon, silicon-oxygen materials, and silicon-carbon materials.
  6. 如权利要求1至5任一项所述的负极极片，其中所述负极活性物质层为单层，所述负极活性物质层的厚度为46.9～126.6μm。The negative electrode sheet according to any one of claims 1 to 5, wherein the negative active material layer is a single layer, and the thickness of the negative active material layer is 46.9-126.6 μm.
  7. 如权利要求6所述的负极极片，其中所述第一导电剂在所述负极活性物质层中的质量占比为0.5～5％；所述第二导电剂在所述负极活性物质层中的质量占比为0.005～6％。The negative electrode sheet according to claim 6, wherein the mass proportion of the first conductive agent in the negative active material layer is 0.5 to 5%; the second conductive agent in the negative active material layer The mass proportion is 0.005~6%.
  8. 如权利要求6至7任一项所述的负极极片，其中所述碳基活性材料与所述硅基活性材料的质量比为(75～100):(0～25)。The negative electrode sheet according to any one of claims 6 to 7, wherein the mass ratio of the carbon-based active material to the silicon-based active material is (75-100): (0-25).
  9. 如权利要求1至5任一项所述的负极极片，其中所述负极活性物质层包括：The negative electrode sheet according to any one of claims 1 to 5, wherein the negative active material layer includes:
    第一负极活性物质层，位于所述负极集流体的至少一个表面上，所述第一负极活性物质层的导通因子记为i 1，则所述第一负极活性物质层的导通因子满足：0.1≤i 1≤6； The first negative active material layer is located on at least one surface of the negative current collector. The conduction factor of the first negative active material layer is denoted as i 1 , then the conduction factor of the first negative active material layer satisfies :0.1≤i 1 ≤6;
    第二负极活性物质层，位于所述第一负极活性物质层远离所述负极集流体的表面上，所述第二负极活性物质层的导通因子记为i 2，则所述第二负极活性物质层的导通因子满足：0＜i 2≤0.75。 The second negative electrode active material layer is located on the surface of the first negative electrode active material layer away from the negative electrode current collector. The conduction factor of the second negative electrode active material layer is denoted as i 2 , then the second negative electrode active material layer The conduction factor of the material layer satisfies: 0＜i 2 ≤0.75.
  10. 如权利要求9所述的负极极片，其中所述第一负极活性物质层中硅基材料的质量占比大于所述第二负极活性物质层中硅基材料的质量占比；The negative electrode sheet according to claim 9, wherein the mass proportion of the silicon-based material in the first negative active material layer is greater than the mass proportion of the silicon-based material in the second negative active material layer;
    可选地，所述第一负极活性物质层中碳基材料和硅基材料的质量比为(75～95):(5～25)；所述第二负极活性物质层中碳基材料和硅基材料的质量占比为(90～100):(0～10)。Optionally, the mass ratio of the carbon-based material and the silicon-based material in the first negative active material layer is (75-95): (5-25); the carbon-based material and silicon in the second negative active material layer are The mass ratio of the base material is (90~100): (0~10).
  11. 如权利要求9至10任一项所述的负极极片，其中所述第一导电剂在所述第一负极活性物质层中的质量占比为0.5～5％；所述第二导电剂在所述第一负极活性物质层中的质量占比为0.05～6％。The negative electrode sheet according to any one of claims 9 to 10, wherein the mass proportion of the first conductive agent in the first negative active material layer is 0.5-5%; the second conductive agent is in The mass proportion of the first negative active material layer is 0.05-6%.
  12. 如权利要求9至11任一项所述的负极极片，其中所述第一导电剂在所述第二负极活性物质层中的质量占比为0.5～5％；所述第二导电剂在所述第二负极活性物质层中的质量占比为0～3％。The negative electrode sheet according to any one of claims 9 to 11, wherein the mass proportion of the first conductive agent in the second negative electrode active material layer is 0.5-5%; the second conductive agent is in The mass proportion of the second negative active material layer is 0-3%.
  13. 如权利要求9至12任一项所述的负极极片，其中所述第一负极活性物质层和所述第二负极活性物质层的厚度之和为46.9～126.6μm；The negative electrode sheet according to any one of claims 9 to 12, wherein the sum of the thicknesses of the first negative active material layer and the second negative active material layer is 46.9-126.6 μm;
    可选地，所述第一负极活性物质层和所述第二负极活性物质层的厚度之比为(0.25～0.67):1。Optionally, the thickness ratio of the first negative active material layer and the second negative active material layer is (0.25˜0.67):1.
  14. 如权利要求1至13任一项所述的负极极片，其中所述负极极片的极片面密度为8.4mg/cm 2～13mg/cm 2。 The negative electrode piece according to any one of claims 1 to 13, wherein the negative electrode piece has an area density of 8.4 mg/cm 2 to 13 mg/cm 2 .
  15. 一种二次电池，包括如权利要求1至14任一项所述的负极极片。A secondary battery including the negative electrode plate according to any one of claims 1 to 14.
  16. 一种用电装置，包括如权利要求15所述的二次电池。An electrical device including the secondary battery according to claim 15.
PCT/CN2022/118684 2022-09-14 2022-09-14 Negative electrode sheet, secondary battery and electric apparatus WO2024055188A1 (en)

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Citations (4)

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Publication number Priority date Publication date Assignee Title
JP2015053165A (en) * 2013-09-06 2015-03-19 日立化成株式会社 Positive electrode for lithium ion secondary batteries, and lithium ion secondary battery
CN109980199A (en) * 2019-03-20 2019-07-05 宁德新能源科技有限公司 Negative electrode active material and preparation method thereof and the device for using the negative electrode active material
CN112670445A (en) * 2020-12-22 2021-04-16 银隆新能源股份有限公司 Lithium ion battery cathode, preparation method thereof and lithium ion battery
WO2021251663A1 (en) * 2020-06-11 2021-12-16 주식회사 엘지에너지솔루션 Anode and secondary battery comprising same

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2015053165A (en) * 2013-09-06 2015-03-19 日立化成株式会社 Positive electrode for lithium ion secondary batteries, and lithium ion secondary battery
CN109980199A (en) * 2019-03-20 2019-07-05 宁德新能源科技有限公司 Negative electrode active material and preparation method thereof and the device for using the negative electrode active material
WO2021251663A1 (en) * 2020-06-11 2021-12-16 주식회사 엘지에너지솔루션 Anode and secondary battery comprising same
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