CN115172663A - Composite negative pole piece and preparation method and application thereof - Google Patents

Composite negative pole piece and preparation method and application thereof Download PDF

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CN115172663A
CN115172663A CN202210528244.1A CN202210528244A CN115172663A CN 115172663 A CN115172663 A CN 115172663A CN 202210528244 A CN202210528244 A CN 202210528244A CN 115172663 A CN115172663 A CN 115172663A
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active layer
negative electrode
active material
carbon
conductive agent
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王坤
成小康
苏威同
田冰冰
李真棠
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Guangdong Carriage Power Technology Co ltd
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Guangdong Carriage Power Technology Co ltd
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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
    • 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
    • H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • 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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • 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
    • H01M4/134—Electrodes based on metals, Si or alloys
    • 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
    • H01M4/139—Processes of manufacture
    • H01M4/1393—Processes of manufacture of electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • 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
    • H01M4/139—Processes of manufacture
    • H01M4/1395—Processes of manufacture of electrodes based on metals, Si or alloys
    • 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
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0085—Immobilising or gelification of electrolyte
    • 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

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Abstract

The invention discloses a composite negative pole piece and a preparation method and application thereof, wherein the composite negative pole piece comprises a current collector, a first active layer arranged on the upper surface and the lower surface of the current collector, and a second active layer arranged on the first active layer, wherein the materials of the first active layer and the second active layer respectively comprise active substances, a conductive agent, a binder, a thickening agent and solid electrolyte; the active materials in the first active layer and the second active layer are different materials, or the material of the first active layer is the same as the material forming the second active layer, but the mass ratio of the active materials to the conductive agent in the first active layer to the second active layer is different. The battery cell composed of the composite negative pole piece provided by the invention can obtain excellent comprehensive properties such as high energy density, high rate performance, high safety performance, long cycle performance, low cost and the like.

Description

Composite negative pole piece and preparation method and application thereof
Technical Field
The invention relates to the technical field of negative electrode materials, in particular to a composite negative electrode plate and a preparation method and application thereof.
Background
From the commercial application, the lithium ion battery is distinguished from various energy storage technologies by virtue of the advantages of the lithium ion battery in the aspects of energy density, voltage platform, cycle life, no memory effect, environmental protection, self-discharge, stability and the like, and is widely applied to various consumer electronics products, electric vehicles, energy storage power stations and the like.
However, with the widespread use of lithium ion batteries in consumer electronics, electric vehicles, energy storage, and other applications, the current lithium ion battery technology has difficulty in meeting the requirements for comprehensive properties such as energy density, rate capability, cycle performance, quick charge performance, high and low temperature performance, stability, safety performance, and cost.
Accordingly, the prior art is yet to be improved and developed.
Disclosure of Invention
In view of the defects of the prior art, the invention aims to provide a composite negative electrode plate and a preparation method and application thereof, and aims to solve the problem that the conventional lithium ion battery negative electrode material is poor in comprehensive electrical property.
The technical scheme of the invention is as follows:
a composite negative pole piece comprises a current collector, first active layers arranged on the upper surface and the lower surface of the current collector, and a second active layer arranged on the first active layer, wherein the material for forming the first active layer comprises a first negative pole active substance, a first conductive agent, a first binder, a first thickening agent and a first solid electrolyte, and the material for forming the second active layer comprises a second negative pole active substance, a second conductive agent, a second binder, a second thickening agent and a second solid electrolyte; the first negative electrode active material and the second negative electrode active material are different materials, or the material forming the first active layer and the material forming the second active layer are the same, the mass ratio of the first negative electrode active material in the first active layer is different from the mass ratio of the second negative electrode active material in the second active layer, and the mass ratio of the first conductive agent in the first active layer is different from the mass ratio of the second conductive agent in the second active layer.
The composite negative electrode plate is characterized in that the first negative active material is one of artificial graphite, a silicon-carbon material, natural graphite, carbon black, carbon fiber, a carbon nanotube, graphene, hard carbon, silicon, tin and silicon monoxide; the second negative active material is one of artificial graphite, a silicon-carbon material, natural graphite, carbon black, carbon fiber, a carbon nanotube, graphene, hard carbon, silicon, tin and silicon monoxide.
The composite negative electrode plate is characterized in that the first negative active material is artificial graphite, and the second negative active material is a silicon-carbon material.
The composite negative electrode plate is characterized in that the first negative electrode active material is artificial graphite, and the second negative electrode active material is hard carbon.
The composite negative electrode plate is characterized in that the first negative electrode active substance is artificial graphite, and the second negative electrode active substance is natural graphite.
The composite negative electrode plate is characterized in that the material for forming the first active layer comprises, by mass, 70-88% of a first negative electrode active material, 0.5-5% of a first conductive agent, 0.5-5% of a first binder, 0.5-5% of a first thickening agent and 5-20% of a first solid electrolyte; the material forming the second active layer comprises, by mass, 70-88% of a second negative electrode active material, 0.5-5% of a second conductive agent, 0.5-5% of a second binder, 0.5-5% of a second thickener, and 5-20% of a second solid electrolyte.
The composite negative pole piece is characterized in that the first conductive agent and the second conductive agent are independently selected from one or more of conductive carbon black, single-walled carbon nanotubes, multi-walled carbon nanotubes, graphene, ketjen black, conductive graphite and carbon fibers; the first binder and the second binder are independently selected from one or more of styrene butadiene rubber, modified styrene butadiene rubber, nitrile butadiene rubber, polyacrylic acid, sodium polyacrylate, polyacrylonitrile and polyacrylate; the first thickening agent and the second thickening agent are independently selected from one or two of carboxymethyl cellulose and polyether modified organic silicon polymer; the first solid electrolyte and the second solid electrolyte are independently selected from one or more of lithium lanthanum zirconium oxygen, lithium lanthanum zirconium tantalum oxygen, lithium lanthanum titanium oxygen, titanium aluminum lithium phosphate, zirconium lithium phosphate, germanium aluminum lithium phosphate, lithium germanium phosphorus sulfur, lithium phosphorus sulfur chloride, lithium phosphorus sulfur bromide and lithium phosphorus sulfur iodide.
A preparation method of a composite negative pole piece comprises the following steps:
mixing a first negative electrode active material, a first conductive agent, a first binder, a first thickener, a first solid electrolyte and deionized water to form first slurry;
mixing a second negative electrode active material, a second conductive agent, a second binder, a second thickener, a second solid electrolyte and deionized water to form a second slurry,
coating the first slurry on the upper surface and the lower surface of a current collector to form a first active layer;
and coating the second slurry on the surface of the first active layer to form a second active layer, so as to obtain the composite negative pole piece.
The application of the composite negative pole piece is characterized in that the composite negative pole piece is used for preparing an all-solid-state lithium ion battery.
Has the advantages that: the composite negative pole piece provided by the invention is of a double-layer structure and comprises a first active layer and a second active layer, the composite negative pole piece of the double-layer structure can avoid the defects of one active layer, obtain the advantages of the other active layer and achieve the effect of bringing out the best in each other, so that a battery cell consisting of the composite negative pole piece can obtain excellent comprehensive performances such as high energy density, high rate capability, high safety performance, long cycle performance, low cost and the like.
Drawings
Fig. 1 is a schematic structural diagram of a composite negative electrode plate according to the present invention.
Detailed Description
The invention provides a composite negative pole piece and a preparation method and application thereof, and the invention is further explained in detail below in order to make the purpose, technical scheme and effect of the invention clearer and clearer. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Referring to fig. 1, fig. 1 is a schematic structural diagram of a composite negative electrode plate provided in the present invention, and as shown in the figure, the composite negative electrode plate includes a current collector 10, a first active layer 20 disposed on upper and lower surfaces of the current collector 10, and a second active layer 30 disposed on the first active layer 20, a material forming the first active layer 20 includes a first negative electrode active material, a first conductive agent, a first binder, a first thickener, and a first solid electrolyte, and a material forming the second active layer 30 includes a second negative electrode active material, a second conductive agent, a second binder, a second thickener, and a second solid electrolyte; the first negative electrode active material and the second negative electrode active material are different materials, or the material forming the first active layer and the material forming the second active layer are the same, the mass ratio of the first negative electrode active material in the first active layer is different from the mass ratio of the second negative electrode active material in the second active layer, and the mass ratio of the first conductive agent in the first active layer is different from the mass ratio of the second conductive agent in the second active layer.
In the composite negative electrode plate provided by the invention, the first negative active material and the second negative active material are different materials, which means that the first negative active material and the second negative active material are different materials in gram capacity, compacted density, rate capability, safety performance, cycle performance or cost, so that the composite negative electrode plate with a double-layer structure formed by different active material materials can avoid the defects of one active layer, obtain the advantages of the other active layer, achieve the effect of complementing each other, and enable a battery cell formed by the composite negative electrode plate to obtain excellent comprehensive properties such as high energy density, high rate capability, high safety performance, long cycle performance, low cost and the like.
In the composite negative electrode plate provided by the invention, the material for forming the first active layer is the same as the material for forming the second active layer, and the mass ratio of the first negative electrode active material to the first conductive agent in the first active layer is different from the mass ratio of the second negative electrode active material to the second conductive agent in the second active layer. That is to say, the formula proportions of the first active layer and the second active layer in the composite negative electrode sheet are different, and the composite negative electrode sheet with a double-layer structure formed under the condition can avoid the defects of one active layer, obtain the advantages of the other active layer and achieve the effect of complementing each other, so that the battery cell formed by the composite negative electrode sheet can obtain excellent comprehensive performances such as high energy density, high rate capability, high safety performance, long cycle performance, low cost and the like.
In some embodiments, the first negative active material is one of artificial graphite, a silicon carbon material, natural graphite, carbon black, carbon fiber, carbon nanotube, graphene, hard carbon, silicon, tin, and silica, but is not limited thereto. The second negative active material is one of artificial graphite, silicon carbon material, natural graphite, carbon black, carbon fiber, carbon nanotube, graphene, hard carbon, silicon, tin, and silica, but is not limited thereto.
In some specific embodiments, a composite negative electrode sheet is provided, which includes a current collector, a first active layer disposed on upper and lower surfaces of the current collector, and a second active layer disposed on the first active layer, wherein a material forming the first active layer includes a first negative electrode active material, a first conductive agent, a first binder, a first thickener, and a first solid electrolyte, and a material forming the second active layer includes a second negative electrode active material, a second conductive agent, a second binder, a second thickener, and a second solid electrolyte; the first negative electrode active material is artificial graphite, and the second negative electrode active material is a silicon carbon material. In this embodiment, since the silicon-carbon material has higher energy density and high dynamic performance compared with the artificial graphite, when the composite negative electrode plate provided by this embodiment is used for preparing an all-solid-state lithium ion battery, the energy density of the battery can be effectively increased, the rate capability and the fast charging performance of the battery can be improved, and the electrical performance and the safety performance of the battery can be improved.
In some specific embodiments, there is also provided a composite negative electrode sheet including a current collector, a first active layer disposed on upper and lower surfaces of the current collector, and a second active layer disposed on the first active layer, wherein a material forming the first active layer includes a first negative electrode active material, a first conductive agent, a first binder, a first thickener, and a first solid electrolyte, and a material forming the second active layer includes a second negative electrode active material, a second conductive agent, a second binder, a second thickener, and a second solid electrolyte; the first negative electrode active material is artificial graphite, and the second negative electrode active material is hard carbon. In this embodiment, since the hard carbon has better dynamic performance and safety performance than artificial graphite, when the composite negative electrode sheet provided by this embodiment is used for preparing an all-solid-state lithium ion battery, the dynamic performance, cycle performance, and safety performance of the battery can be effectively improved.
In some specific embodiments, there is also provided a composite negative electrode sheet including a current collector, a first active layer disposed on upper and lower surfaces of the current collector, and a second active layer disposed on the first active layer, wherein a material forming the first active layer includes a first negative electrode active material, a first conductive agent, a first binder, a first thickener, and a first solid electrolyte, and a material forming the second active layer includes a second negative electrode active material, a second conductive agent, a second binder, a second thickener, and a second solid electrolyte; the first negative electrode active material is artificial graphite, and the second negative electrode active material is natural graphite. In this embodiment, since natural graphite has higher dynamic performance and lower cost than artificial graphite, when the composite negative electrode sheet provided in this embodiment is used to prepare an all-solid-state lithium ion battery, the dynamic performance of the battery can be effectively improved, and the manufacturing cost of the battery can be reduced.
In some embodiments, the material forming the first active layer includes, in mass percent, 70 to 88% of a first negative electrode active material, 0.5 to 5% of a first conductive agent, 0.5 to 5% of a first binder, 0.5 to 5% of a first thickener, and 5 to 20% of a first solid electrolyte; the material forming the second active layer includes, by mass, 70 to 88% of a second negative electrode active material, 0.5 to 5% of a second conductive agent, 0.5 to 5% of a second binder, 0.5 to 5% of a second thickener, and 5 to 20% of a second solid electrolyte.
In some embodiments, the first and second conductive agents are independently selected from one or more of conductive carbon black, single-walled carbon nanotubes, multi-walled carbon nanotubes, graphene, ketjen black, conductive graphite, and carbon fibers, but are not limited thereto. The first conductive agent and the second conductive agent may be the same or different.
In some embodiments, the first binder and the second binder are independently selected from one or more of styrene-butadiene rubber, modified styrene-butadiene rubber, nitrile-butadiene rubber, polyacrylic acid, sodium polyacrylate, polyacrylonitrile, and polyacrylate, but are not limited thereto. The first binder and the second binder may be the same or different.
In some embodiments, the first and second thickeners are independently selected from one or two of carboxymethyl cellulose, polyether modified silicone polymer, but are not limited thereto. The first thickener and the second thickener may be the same or different.
In some embodiments, the first solid state electrolyte and the second solid state electrolyte are independently selected from one or more of lithium lanthanum zirconium oxygen, lithium lanthanum zirconium tantalum oxygen, lithium lanthanum titanium oxygen, lithium titanium aluminum phosphate, lithium zirconium phosphate, lithium germanium aluminum phosphate, lithium germanium phosphorous sulfide, lithium phosphorous sulfide chloride, lithium phosphorous sulfide bromide, and lithium phosphorous sulfide iodide, but are not limited thereto. The first solid state electrolyte and the second solid state electrolyte may be the same or different.
In some embodiments, there is also provided a method of making a composite negative electrode sheet, comprising the steps of:
s10, mixing a first negative electrode active material, a first conductive agent, a first binder, a first thickening agent, a first solid electrolyte and deionized water to form first slurry;
s20, mixing a second negative electrode active material, a second conductive agent, a second binder, a second thickening agent, a second solid electrolyte and deionized water to form second slurry,
s30, coating the first slurry on the upper surface and the lower surface of a current collector to form a first active layer;
and S40, coating the second slurry on the surface of the first active layer to form a second active layer, and thus obtaining the composite negative pole piece.
The preparation method of the composite negative pole piece provided by the embodiment is simple and easy to operate, the prepared composite negative pole piece is of a double-layer structure and comprises a first active layer and a second active layer, the composite negative pole piece of the double-layer structure can avoid the defect of one active layer, and the advantage of the other active layer is obtained, so that the effect of bringing out the best in each other is achieved, and the battery cell formed by the composite negative pole piece can obtain excellent comprehensive performances such as high energy density, high rate capability, high safety performance, long cycle performance, low cost and the like.
In some embodiments, the application of the composite negative electrode plate is also provided, wherein the composite negative electrode plate is used for preparing an all-solid-state lithium ion battery. In this embodiment, the all-solid-state lithium ion battery further includes a solid electrolyte and a positive electrode plate, the solid electrolyte is not limited in this embodiment, and may be any known solid electrolyte that can be used in a lithium ion battery, such as lithium lanthanum zirconium oxygen, lithium lanthanum zirconium tantalum oxygen, lithium lanthanum titanium oxygen, titanium aluminum lithium phosphate, zirconium lithium phosphate, germanium aluminum lithium phosphate, lithium germanium phosphorus sulfur, lithium phosphorus sulfur chloride, lithium phosphorus sulfur bromide, lithium phosphorus sulfur iodide, and the like. The active material of the positive electrode plate is not limited in this embodiment, and may be any one of or a combination of at least two of active materials known to be used in a positive electrode material of a lithium ion battery, such as lithium iron phosphate, lithium cobaltate, ternary nickel-cobalt-manganese, ternary nickel-cobalt-aluminum, lithium manganate, and the like. And separating the negative pole piece from the negative pole piece through solid electrolyte to form an electrode group, placing the motor group into a battery case, and sealing the battery case to obtain the all-solid-state lithium ion battery.
The invention is further illustrated by the following specific examples:
example 1
The first negative active material layer slurry is formed by mixing 86.15% of artificial graphite, 0.8% of conductive carbon black, 0.05% of carbon nano tubes, 1.8% of styrene butadiene rubber, 1.2% of carboxymethyl cellulose, 10% of lithium lanthanum zirconium oxygen solid electrolyte and deionized water, and is coated on the surface of the carbon-coated copper foil to form a first negative active material layer; the second negative electrode active material layer slurry is formed by mixing 86.15% of silicon carbon negative electrode material, 0.8% of conductive carbon black, 0.05% of carbon nano tube, 1.8% of styrene butadiene rubber, 1.2% of carboxymethyl cellulose, 10% of lithium lanthanum zirconium oxygen solid electrolyte and deionized water, and is coated on the surface of the first negative electrode active material layer to form a second negative electrode active material layer. The density of the coating surface of the first negative electrode active material layer was 21g/m 2 The second negative electrode active material layer coating surface density was 70g/m 2 。
Example 2
The first negative active material layer slurry is formed by mixing 86.15% of artificial graphite 1, 0.8% of conductive carbon black, 0.05% of carbon nano tubes, 1.8% of styrene butadiene rubber, 1.2% of carboxymethyl cellulose, 10% of lithium lanthanum zirconium oxygen solid electrolyte and deionized water, and is coated on the surface of the carbon-coated copper foil to form a first negative active material layer; the second negative active material layer slurry is formed by mixing 86.15% of artificial graphite 2, 0.8% of conductive carbon black, 0.05% of carbon nano tubes, 1.8% of styrene butadiene rubber, 1.2% of carboxymethyl cellulose, 10% of lithium lanthanum zirconium oxygen solid electrolyte and deionized water, and is coated on the surface of the first negative active material layer to form a second negative active material layer. The artificial graphite 2 has better dynamic performance than the artificial graphiteThe graphite 1 is better, the gram capacity is lower, but the cost is lower. The density of the coating surface of the first negative electrode active material layer is 32g/m 2 The second negative electrode active material layer coating surface density was 70g/m 2 。
Example 3
The first negative active material layer slurry is formed by mixing 86.15% of artificial graphite, 0.8% of conductive carbon black, 0.05% of carbon nano tubes, 1.8% of styrene butadiene rubber, 1.2% of carboxymethyl cellulose, 10% of lithium lanthanum zirconium oxygen solid electrolyte and deionized water, and is coated on the surface of the carbon-coated copper foil to form a first negative active material layer; the second negative electrode active material layer slurry is formed by mixing 86.15% of hard carbon, 0.8% of conductive carbon black, 0.05% of carbon nano tubes, 1.8% of styrene butadiene rubber, 1.2% of carboxymethyl cellulose, 10% of lithium lanthanum zirconium oxygen solid electrolyte and deionized water, and is coated on the surface of the first negative electrode active material layer to form a second negative electrode active material layer. The coating surface density of the first negative electrode active material layer is 34g/m 2 The second negative electrode active material layer coating surface density was 70g/m 2 。
Example 4
The first negative active material layer slurry is formed by mixing 86.15% of artificial graphite, 0.8% of conductive carbon black, 0.05% of carbon nano tubes, 1.8% of styrene butadiene rubber, 1.2% of carboxymethyl cellulose, 10% of lithium lanthanum zirconium oxygen solid electrolyte and deionized water, and is coated on the surface of the carbon-coated copper foil to form a first negative active material layer; the second negative active material layer slurry is formed by mixing 85.6% of artificial graphite, 1.3% of conductive carbon black, 0.1% of carbon nano tubes, 1.8% of styrene butadiene rubber, 1.2% of carboxymethyl cellulose, 10% of lithium lanthanum zirconium oxygen solid electrolyte and deionized water, and is coated on the surface of the first negative active material layer to form a second negative active material layer. The density of the coating surface of the first negative electrode active material layer is 30g/m 2 The second negative electrode active material layer coating surface density was 70g/m 2 。
Example 5
The first negative active material layer slurry is formed by mixing 86.15% of artificial graphite, 0.8% of conductive carbon black, 0.05% of carbon nano tube, 1.8% of styrene butadiene rubber, 1.2% of carboxymethyl cellulose, 10% of lithium lanthanum zirconium oxygen solid electrolyte and deionized water to form slurryCoating the carbon-coated copper foil on the surface to form a first negative active material layer; the second negative electrode active material layer slurry is formed by mixing 86.15% of natural graphite, 0.8% of conductive carbon black, 0.05% of carbon nanotubes, 1.8% of styrene butadiene rubber, 1.2% of carboxymethyl cellulose, 10% of lithium lanthanum zirconium oxygen solid electrolyte and deionized water, and is coated on the surface of the first negative electrode active material layer to form a second negative electrode active material layer. The density of the coating surface of the first negative electrode active material layer is 30g/m 2 The second negative electrode active material layer coating surface density was 70g/m 2 。
Comparative example 1
The active substance layer slurry is prepared by mixing 86.15% of artificial graphite, 0.8% of conductive carbon black, 0.05% of carbon nano tube, 1.8% of styrene butadiene rubber, 1.2% of carboxymethyl cellulose, 10% of lithium lanthanum zirconium oxygen solid electrolyte and deionized water, and coating the obtained slurry on the surface of the carbon-coated copper foil to form a negative pole piece, wherein the coating surface density is 100g/m 2 。
The negative electrode plate of example 1 and the negative electrode plate of comparative example 1 were assembled into an all-solid-state lithium ion battery, and the energy density, rate capability and safety performance of the battery were evaluated, and the results are shown in table 1.
Table 1 results of performance testing
Figure BDA0003645486230000101
As can be seen from the data in table 1, the double-layer structure composite negative electrode plate prepared in embodiment 1 of the present invention can utilize the high energy density and high dynamic performance of the second active layer, namely the silicon-carbon material, to improve the energy density of the battery cell, improve the rate capability and the fast charging performance, and improve the electrical performance and the safety performance of the all-solid-state battery.
The cathode plates in example 2 and comparative example 1 were assembled into an all-solid-state lithium ion battery, and the rate performance, the cycle capacity retention rate, and the cost of the battery were evaluated, and the results are shown in table 2.
Table 2 results of performance testing
Figure BDA0003645486230000102
Figure BDA0003645486230000111
As can be seen from the data in table 2, the double-layer structure composite negative electrode plate prepared in embodiment 2 of the present invention can improve the dynamic performance and the cycle performance of the battery cell by using the better dynamic performance of the second active layer artificial graphite 2, and reduce the battery cell cost.
The negative electrode plates in example 3 and comparative example 1 were assembled into an all-solid-state lithium ion battery, and the rate performance, the cycle capacity retention rate, and the puncture throughput of the battery were evaluated, and the results are shown in table 3.
TABLE 3 results of Performance testing
Figure BDA0003645486230000112
As can be seen from the data in table 3, the double-layer structure composite negative electrode plate prepared in embodiment 3 of the present invention can utilize the high dynamics and high safety performance of the hard carbon of the second active layer, so as to improve the dynamic performance, cycle performance and safety performance of the battery cell.
The negative electrode plates in example 4 and comparative example 1 were assembled into an all-solid-state lithium ion battery, and the rate performance, the cycle capacity retention rate, and the safety performance of the battery were evaluated, with the results shown in table 4.
Table 4 results of performance testing
Figure BDA0003645486230000113
Figure BDA0003645486230000121
As can be seen from the data in table 4, the double-layer structure composite negative electrode plate prepared in embodiment 4 of the present invention has the advantage that the conductivity of the composite negative electrode plate can be improved due to the increased content of the conductive agent in the second active layer, so as to improve the dynamic performance and the cycle performance of the battery cell.
The cathode pole pieces in example 5 and comparative example 1 were assembled into an all-solid-state lithium ion battery, and the rate performance, safety performance, and cost of the battery were evaluated, with the results shown in table 5.
TABLE 5 results of Performance testing
Figure BDA0003645486230000122
As can be seen from the data in table 5, the double-layer structure composite negative electrode plate prepared in embodiment 5 of the present invention can improve the cell dynamic performance and reduce the cell cost by using the advantages of high dynamic performance and low cost of the natural graphite in the second active layer.
In summary, the composite negative electrode plate provided by the invention has a double-layer structure, and includes the first active layer and the second active layer, the composite negative electrode plate with the double-layer structure can avoid the disadvantage of one active layer, and obtain the advantage of the other active layer, so as to achieve the effect of bringing out the best in each other, and thus, a battery cell composed of the composite negative electrode plate can obtain excellent comprehensive properties such as high energy density, high rate capability, high safety performance, long cycle performance, low cost, and the like.
It will be understood that the invention is not limited to the examples described above, but that modifications and variations will occur to those skilled in the art in light of the above teachings, and that all such modifications and variations are considered to be within the scope of the invention as defined by the appended claims.

Claims (9)

1. A composite negative pole piece is characterized by comprising a current collector, first active layers arranged on the upper surface and the lower surface of the current collector, and a second active layer arranged on the first active layer, wherein the material for forming the first active layer comprises a first negative active substance, a first conductive agent, a first binder, a first thickening agent and a first solid electrolyte, and the material for forming the second active layer comprises a second negative active substance, a second conductive agent, a second binder, a second thickening agent and a second solid electrolyte; the first negative electrode active material and the second negative electrode active material are different materials, or the material forming the first active layer and the material forming the second active layer are the same, the mass ratio of the first negative electrode active material in the first active layer is different from the mass ratio of the second negative electrode active material in the second active layer, and the mass ratio of the first conductive agent in the first active layer is different from the mass ratio of the second conductive agent in the second active layer.
2. The composite negative electrode sheet according to claim 1, wherein the first negative active material is one of artificial graphite, silicon carbon material, natural graphite, carbon black, carbon fiber, carbon nanotube, graphene, hard carbon, silicon, tin and silicon monoxide; the second negative active material is one of artificial graphite, a silicon-carbon material, natural graphite, carbon black, carbon fiber, a carbon nanotube, graphene, hard carbon, silicon, tin and silicon monoxide.
3. The composite negative electrode sheet according to claim 2, wherein the first negative active material is artificial graphite and the second negative active material is a silicon carbon material.
4. The composite negative electrode sheet according to claim 2, wherein the first negative active material is artificial graphite and the second negative active material is hard carbon.
5. The composite negative electrode sheet according to claim 2, wherein the first negative electrode active material is artificial graphite and the second negative electrode active material is natural graphite.
6. The composite negative electrode sheet according to claim 1, wherein the material forming the first active layer comprises, by mass, 70 to 88% of a first negative electrode active material, 0.5 to 5% of a first conductive agent, 0.5 to 5% of a first binder, 0.5 to 5% of a first thickener, and 5 to 20% of a first solid electrolyte; the material forming the second active layer comprises, by mass, 70-88% of a second negative electrode active material, 0.5-5% of a second conductive agent, 0.5-5% of a second binder, 0.5-5% of a second thickener, and 5-20% of a second solid electrolyte.
7. The composite negative electrode plate as claimed in any one of claims 1 to 6, wherein the first conductive agent and the second conductive agent are independently selected from one or more of conductive carbon black, single-walled carbon nanotube, multi-walled carbon nanotube, graphene, ketjen black, conductive graphite and carbon fiber; the first binder and the second binder are independently selected from one or more of styrene-butadiene rubber, modified styrene-butadiene rubber, nitrile-butadiene rubber, polyacrylic acid, sodium polyacrylate, polyacrylonitrile and polyacrylate; the first thickening agent and the second thickening agent are independently selected from one or two of carboxymethyl cellulose and polyether modified organic silicon polymer; the first solid electrolyte and the second solid electrolyte are independently selected from one or more of lithium lanthanum zirconium oxygen, lithium lanthanum zirconium tantalum oxygen, lithium lanthanum titanium oxygen, titanium aluminum lithium phosphate, zirconium lithium phosphate, germanium aluminum lithium phosphate, lithium germanium phosphorus sulfur, lithium phosphorus sulfur chloride, lithium phosphorus sulfur bromide and lithium phosphorus sulfur iodide.
8. A preparation method of the composite negative pole piece as claimed in any one of claims 1 to 7, characterized by comprising the steps of:
mixing a first negative electrode active material, a first conductive agent, a first binder, a first thickener, a first solid electrolyte and deionized water to form a first slurry;
mixing a second negative electrode active material, a second conductive agent, a second binder, a second thickener, a second solid electrolyte and deionized water to form a second slurry,
coating the first slurry on the upper surface and the lower surface of a current collector to form a first active layer;
and coating the second slurry on the surface of the first active layer to form a second active layer, so as to obtain the composite negative pole piece.
9. The application of the composite negative pole piece as claimed in any one of claims 1 to 7, wherein the composite negative pole piece is used for preparing an all-solid-state lithium ion battery.
CN202210528244.1A 2022-05-16 2022-05-16 Composite negative pole piece and preparation method and application thereof Pending CN115172663A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115986062A (en) * 2023-01-31 2023-04-18 重庆长安新能源汽车科技有限公司 Multi-level nano-porous gradient pole piece, preparation method and lithium ion battery

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115986062A (en) * 2023-01-31 2023-04-18 重庆长安新能源汽车科技有限公司 Multi-level nano-porous gradient pole piece, preparation method and lithium ion battery

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