CN109390554A - Negative plate, lithium-rich negative plate thereof, lithium ion secondary battery and preparation method - Google Patents

Negative plate, lithium-rich negative plate thereof, lithium ion secondary battery and preparation method Download PDF

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Publication number
CN109390554A
CN109390554A CN201710672180.1A CN201710672180A CN109390554A CN 109390554 A CN109390554 A CN 109390554A CN 201710672180 A CN201710672180 A CN 201710672180A CN 109390554 A CN109390554 A CN 109390554A
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negative electrode
lithium
electrode tab
heat dissipating
active material
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CN109390554B (en
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潘建伟
龚志杰
张盛武
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Contemporary Amperex Technology Co Ltd
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Contemporary Amperex 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
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • 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
    • H01M4/04—Processes of manufacture in general
    • H01M4/0402—Methods of deposition of the material
    • 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
    • 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
    • H01M4/136—Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
    • 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
    • H01M4/1391—Processes of manufacture of electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • 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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1397—Processes of manufacture of electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2220/00—Batteries for particular applications
    • H01M2220/30—Batteries in portable systems, e.g. mobile phone, laptop
    • 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
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    • Y02E60/10—Energy storage using batteries

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Abstract

The application relates to the technical field of energy storage materials, in particular to a negative plate, a lithium-rich negative plate, a lithium ion battery and a preparation method of the lithium-rich negative plate. The negative plate comprises a negative current collector, a negative active material layer and a porous heat dissipation layer, wherein the porous heat dissipation layer contains a compound or a polymer with at least one of structural units shown in a formula I, a formula II and a formula III. The negative pole piece solves the problem that the temperature of the pole piece is too high due to a large amount of heat generated in the process of lithium supplement of the negative pole, and effectively improves the first coulombic efficiency, so that the energy density of the lithium ion secondary battery is greatly improved, and the lithium ion secondary battery is ensured to have good electrochemical performance.

Description

A kind of negative electrode tab and its rich lithium cathode sheet and lithium ion secondary battery and preparation method
Technical field
This application involves energy storage material technical fields, specifically, be related to a kind of negative electrode tab, its rich lithium cathode sheet, its lithium from Sub- secondary cell and preparation method thereof.
Background technique
With the product such as laptop of consumer electronics, mobile phone, handheld device, tablet computer etc. it is universal, greatly Requirement of the family to its battery is also increasingly stringenter；For example require battery should be small and light and high capacity must also be possessed, Long circulating and stable performance.In the secondary battery, lithium ion secondary battery is higher for the battery of other types Energy density advantage makes it inhibit to occupy dominant position on the market.
Silicium cathode battery is the important directions that lithium battery improves energy density at present, and silicium cathode battery coulombic efficiency for the first time It is lower, pre- benefit lithium is needed to improve first effect problem.Quickly embedding lithium reaction can occur in silicium cathode lithium up process and generate big calorimetric Amount, to bring the safety problem in production process.
In the actual production process, silicium cathode benefit lithium can be reduced using dry wind or other physical cooling methods to produce Pole piece temperature in journey, but it can not be fully solved problem, there is a certain security risk；Starting with from the structure of pole piece, it is scattered to increase Hot path is a kind of relatively easy method realized and reduce security risk.In existing heat dissipation layered scheme, in negative electrode active material Setting includes the porous heat dissipating layer of conductive agent and binder between the bed of material and benefit lithium layer, can slow down lithium ion to negative electrode active material Expect the rate of diffusion to reduce rate of heat production.But conductive agent such as conductive black can adsorb lithium ion, cause lithium in lithium up process The utilization rate of ion reduces.
In consideration of it, special propose the application.
Summary of the invention
The primary goal of the invention of the application is to propose a kind of negative electrode tab.
The second goal of the invention of the application is to propose a kind of rich lithium cathode sheet.
The third goal of the invention of the application is to propose its a kind of lithium ion battery.
The 4th goal of the invention of the application is to propose a kind of cathode piece preparation method.
In order to complete the purpose of the application, the technical solution of use are as follows:
This application involves a kind of negative electrode tab, including negative current collector, anode active material layer and porous heat dissipating layer,
The anode active material layer is located on the negative current collector,
The porous heat dissipating layer is located in the anode active material layer；
Contain negative electrode active material in the anode active material layer, the negative electrode active material is selected from silicon, tin, oxidation Silicon, tin oxide, silicon and the composite material of carbon, the composite material of tin and carbon, the halide of silicon, the halide of tin, silicon alloy, tin close At least one of gold；
Contain the compound at least one of structural unit shown in Formulas I, Formula II, formula III in the porous heat dissipating layer Or polymer；
Wherein, R1、R2It is independently selected from C1~C6Alkyl.
Optionally, the polymer with structural unit shown in Formulas I is selected from the polymer as shown in Formulas I A；
Wherein, R1、R2It is independently selected from C1~C3Alkyl, 100≤n≤10000.
Optionally, the compound with structural unit shown in Formula II is selected from the polymer as shown in Formula II A；
Wherein, R1、R2It is independently selected from C1~C3Alkyl, R3Selected from C1~C6Alkylidene, R4Selected from C1~C6Alkyl.
Optionally, the polymer with structural unit shown in formula III is selected from the polymer as shown in formula III A；
Wherein, R1、R2It is independently selected from C1~C3Alkyl, R5、R6It is independently selected from C1~C6Alkylidene, 100≤ m≤10000。
Optionally, polyortho methylaniline, poly- two propylene dimethyl ammonium, dimethyl amine ethyl ester are contained in the porous heat dissipating layer At least one of.
Optionally, the hole coverage rate of the porous heat dissipating layer is 20%~50%.
Optionally, it is preferably 20nm~90nm that the aperture of the porous heat dissipating layer, which is 10nm~120nm,.
Optionally, the thickness of the porous heat dissipating layer can be 0.5 μm~3.5 μm.
Optionally, the negative electrode active material may also include at least one of graphite, amorphous carbon.
The application further relates to a kind of rich lithium cathode sheet, negative electrode tab and metallic lithium layer containing the application, the metallic lithium layer It is set on the porous heat dissipating layer.
The application further relates to a kind of lithium ion secondary battery, and the lithium ion secondary battery includes the rich cathode of lithium of the application Piece.
The application further relates to the preparation method of above-mentioned negative electrode tab, at least includes the following steps:
The anode active material layer is prepared on the negative current collector；
Contain compound or polymer system at least one of structural unit shown in Formulas I, Formula II, formula III for described The solvent of the standby solution for being 0.1~20% at mass percent concentration, the solution is selected from polar solvent, preferably water；
By the solution coating in the anode active material layer, formed after the solvent evaporation in the solution described more Hole heat dissipating layer.
The technical solution of the application at least has following beneficial effect:
Negative electrode tab provided by the present application solves the problems, such as that a large amount of heat production cause pole piece temperature excessively high in cathode lithium up process, Effectively improve using the negative electrode tab lithium ion secondary battery coulombic efficiency for the first time, thus greatly improve lithium from The energy density of sub- secondary cell guarantees that lithium ion secondary battery has good chemical property.
Detailed description of the invention
Fig. 1 is the structural schematic diagram of the negative electrode tab of the embodiment of the present application；
Fig. 2 is the structural schematic diagram of the rich lithium cathode sheet of the embodiment of the present application；
Fig. 3 is the electron scanning micrograph (× 1000 times) of 1 negative electrode tab of comparative example；
Fig. 4 is the electron scanning micrograph (× 5000 times) of the embodiment of the present application negative electrode tab cross section；
Fig. 5 is the electron scanning micrograph (× 50000 times) of the embodiment of the present application negative electrode tab；
Fig. 6 is the pole piece heating temperature test chart of comparative example 1 and embodiment 2.
Wherein:
1- negative electrode tab；
11- negative current collector；
12- anode active material layer；
The porous heat dissipating layer of 13-；
2- richness lithium cathode sheet；
21- metallic lithium layer.
Specific embodiment
Combined with specific embodiments below, the application is further described.It should be understood that these embodiments are merely to illustrate the application Rather than limitation scope of the present application.
[negative electrode tab]
The first aspect of the embodiment of the present application proposes a kind of negative electrode tab, and structural schematic diagram is as shown in Figure 1, negative electrode tab 1 is wrapped Negative current collector 11, anode active material layer 12 and porous heat dissipating layer 13 are included, anode active material layer 12 is located at negative current collector On 11, porous heat dissipating layer 13 is located in anode active material layer 12.
Contain the compound or poly- at least one of structural unit shown in Formulas I, Formula II, formula III in porous heat dissipating layer Close object；
Wherein, R1、R2It is independently selected from C1~C6Alkyl.
The embodiment of the present application by the way that porous heat dissipating layer is arranged on cathode pole piece, contain in porous heat dissipating layer such as Formulas I, formula Structural unit shown in II, formula III has dimethyl amine class formation, and the compound or polymer of the class formation can be self-assembled into porous Structure, to form the heat dissipating layer with porous structure.It is porous to dissipate when carrying out benefit lithium in the negative electrode tab in the embodiment of the present application Cathode membrane and metallic lithium layer are effectively completely cut off between cathode membrane and metallic lithium layer, avoid negative electrode active material by thermosphere Matter (such as silicon, tin) is directly contacted with metallic lithium layer, to slow down the quick embedding lithium reaction in lithium up process, and cathode is effectively reduced Heating problem in piece lithium up process.The heat diffusion that the porous structure of porous heat dissipating layer can assist lithium up process to generate, from And effectively reduce pole piece temperature.Further, the porous structure of heat dissipating layer can make electrolyte abundant in the embodiment of the present application Infiltrate negative electrode tab.If due to non-wetting when battery completely fills, lithium ion can not be embedded in negative electrode active material that (no ion is logical Road), so that battery core is expired cathode membrane surface when filling and blackspot occur, the capacity for influencing battery plays.Therefore, in the embodiment of the present application Porous heat dissipating layer can also improve the infiltration phenomenon of negative electrode tab, further increase secondary cell in addition to great heat radiation effect Capacity retention ratio.
Contain negative electrode active material in anode active material layer in the embodiment of the present application.
Negative electrode active material in the embodiment of the present application includes the coulomb for the first time that battery is caused using the negative electrode active material Efficiency is lower, needs pre- benefit lithium to improve the negative electrode active material of the lower problem of coulombic efficiency for the first time.
Optionally, negative electrode active material is selected from silicon, tin, silica (SiOx, 0 < x≤2), tin oxide (SnOy, 0 < y≤2), Composite material (Sn/C), the halide of silicon, the halide of tin, the silicon alloy, tin of the composite material (Si/C) of silicon and carbon, tin and carbon At least one of alloy；
Specifically, the composite material (Si/C) of silicon and carbon, which refers to, is formed by material after silicon face coats carbon；
The composite material (Sn/C) of tin and carbon, which refers to, is formed by material after tin surfaces coat carbon；
The alloying substance that silicon alloy can be formed for silicon and at least one metallic element, such as the alloy of silicon and tin；
The alloying substance that tin alloy can be formed for tin and at least one metallic element, such as tin and antimony alloy；
The halide of silicon can be selected from silicon chloride；
The halide of tin can be selected from stannic chloride.
Further alternative, negative electrode active material can also add at least one of graphite, amorphous carbon.Optionally, stone Ink, at least one of amorphous carbon can be mixed with above-mentioned negative electrode active material with arbitrary proportion, it is preferred that graphite, amorphous Mass percentage content is 20%~80% at least one of carbon in the negative active material.Further add graphite, without fixed Shape carbon can improve the problem of silicon anode expansion.
In the anode active material layer of the embodiment of the present application, in addition to above-mentioned negative electrode active material, also containing conductive agent and Binder；
Specifically, bonding agent can be selected from butadiene-styrene rubber, polyvinylidene fluoride, polytetrafluoroethylene (PTFE), Viton, polyurethane, One or more of polyacrylic acid, Sodium Polyacrylate, polyvinyl alcohol, alginic acid, sodium alginate.
Conductive agent can be selected from one or more of acetylene black, conductive carbon black, carbon fiber, carbon nanotube, Ketjen black.It is conductive Carbon black can be selected from one or more of Super P, Super S, 350G.
In porous heat dissipating layer in the embodiment of the present application containing in Formulas I, Formula II, structural unit shown in formula III at least A kind of compound or polymer.
Optionally, the porous heat dissipating layer in the embodiment of the present application is by having the function of that self assembly is porous material, has The compound or polymer of structural unit shown at least one of Formulas I, Formula II, formula III are prepared.
Formulas I, Formula II, structural unit shown in formula III have dimethyl amine class formation, the compound or polymer of the class formation After mixing (or dissolution) with polar solvent, in polar solvent evaporation process, Formulas I, Formula II, structural unit institute shown in formula III The dimethyl amine class formation having can be self-assembled into porous structure, and the scanning electron microscope of microstructure such as Fig. 4, Fig. 5 are shone Shown in piece, Fig. 4 is the electron scanning micrograph of negative electrode tab cross section, and Fig. 5 is the scanning electron microscope on negative electrode tab surface Photo.In Fig. 4, it can measure to obtain the thickness of porous heat dissipating layer.
In the embodiment of the present application, the polymer with structural unit shown in Formulas I is selected from the polymer as shown in Formulas I A；
Wherein, R1、R2It is independently selected from C1~C3Alkyl, 100≤n≤10000.
As a kind of improvement of the embodiment of the present application, work as R1、R2When being methyl, polymer shown in Formulas I A is selected from poly- neighbour Methylaniline (POT), concrete structure formula is as follows:
Wherein, 100≤n≤10000.
In the embodiment of the present application, the compound with structural unit shown in Formula II is as shown in Formula II A；
Wherein, R1、R2It is independently selected from C1~C3Alkyl, R3Selected from C1~C6Alkylidene；R4Selected from C1~C6Alkyl.
As a kind of improvement of the embodiment of the present application, work as R1、R2When being methyl, compound shown in Formula II A is specifically such as formula Shown in IIAa；
Further, work as R3When for ethylidene, Formula II Aa compound represented is selected from dimethyl amine ethyl ester, concrete structure formula It is as follows:
In the embodiment of the present application, the polymer with structural unit shown in formula III is selected from the polymer as shown in formula III A；
Wherein, R1、R2It is independently selected from C1~C3Alkyl, R5、R6It is independently selected from C1~C6Alkylidene, 100≤ m≤10000。
Work as R1、R2When being methyl, polymer shown in IIIA is specific as shown in formula III Aa:
Further, work as R5、R6When being methylene, formula III Aa compound represented is selected from poly- two propylene dimethyl ammonium, Concrete structure formula is as follows:
Wherein, 100≤m≤10000.
As a kind of improvement of the embodiment of the present application negative electrode tab, the aperture of porous heat dissipating layer is 10nm~120nm；Preferably 20nm~90nm, more preferably 30nm~80nm.If the aperture of porous heat dissipating layer is excessive, to stop fluid injection before embedding lithium without It helps；If the aperture of porous heat dissipating layer is too small, the dynamic performance of cathode pole piece is influenced.As the embodiment of the present application cathode A kind of improvement of piece, the hole coverage rate of porous heat dissipating layer are 20%~50%.In the embodiment of the present application, the meaning of hole coverage rate Are as follows: porous material accounts for the ratio between anode surface area in porous heat dissipating layer.
If the hole coverage rate of porous heat dissipating layer it is too small can not effective auxiliary heat dissipation, while sufficient lithium ion can not be provided Channel；If the hole coverage rate of porous heat dissipating layer is excessive, heat dissipating layer structure can not be supported, while can not effectively completely cut off negative electrode active Material and metal layer.As a kind of improvement of the embodiment of the present application negative electrode tab, the thickness of porous heat dissipating layer can be 0.5 μm~3.5 μ m.If the blocked up lithium ion transport that will lead to of porous heat dissipating layer is excessively slow, capacity is influenced；If porous heat dissipating layer is excessively thin to be hindered Too fast lithium ion insertion.
[rich lithium cathode sheet]
As the rich lithium cathode sheet of the embodiment of the present application second aspect, structural schematic diagram is as shown in Fig. 2, rich lithium cathode sheet 2 negative electrode tabs 1 and metallic lithium layer 21 containing first aspect in the embodiment of the present application, metallic lithium layer 21 are set to porous heat dissipating layer 13 On.
Wherein, metallic lithium layer can be metallic lithium foil, optionally, metallic lithium foil with a thickness of 1 μm~20 μm.
[lithium ion secondary battery]
Lithium ion secondary battery as the embodiment of the present application third aspect, comprising: positive plate；Negative electrode tab；Isolation film, Every between positive plate and negative electrode tab；And electrolyte.Wherein, negative electrode tab is the rich lithium according to the embodiment of the present application second aspect Negative electrode tab.
[preparation method of negative electrode tab]
As the preparation method of the embodiment of the present application fourth aspect negative electrode tab, at least include the following steps:
Step 1 prepares the anode active material layer on negative current collector；
Step 2 will contain compound or polymer at least one of structural unit shown in Formulas I, Formula II, formula III It is prepared into the solution that mass percent concentration is 0.1~20%；
The solvent of solution is selected from polar solvent, preferably water；
Step 3, by solution coating in the anode active material layer, form porous heat dissipation after the solvent evaporation in solution Layer.
That is, the negative electrode tab of the embodiment of the present application be coating containing in Formulas I, Formula II, structural unit shown in formula III at least The solution of a kind of compound or polymer is prepared after being dried by evaporation；Above compound or polymer self assembles shape At porous heat dissipating layer.
In above-mentioned preparation process, it is 0.1~20% that above compound or polymer, which are prepared into mass percent concentration, Solution, preferably 1~10%；If the concentration of solution is too small, coating weight is too small, if the concentration of solution is excessive, applies Cloth amount is excessive.
It during the preparation process, can by controlling the concentration of above-mentioned solution, and by adjusting coating speed and coating speed ratio Porous heat dissipating layer coating weight is controlled, and then controls the thickness of porous heat dissipating layer.Specific coating speed and coating speed ratio according to Different coating apparatus are set.
As a kind of improvement of the embodiment of the present application preparation method, dry temperature is 50 DEG C~100 DEG C.If dry Temperature is excessively high, then coating is easy to crack, the easy clot of pole piece；If dry temperature is too low, underdry leads to lower process excellent rate Decline.
During the preparation process, by control coating weight and drying condition, the aperture and hole of porous heat dissipating layer be can control Coverage rate.Under the conditions of the coating weight of the embodiment of the present application and drying temperature, the aperture of the porous heat dissipating layer of the application can control Within the above range with hole coverage rate.
As a kind of improvement of the embodiment of the present application preparation method, coating method is selected from extrusion coated, transfer spraying or micro- Intaglio plate coating.
Below by way of specific embodiment and comparative example, the application is described in detail, these embodiments are only intended to Bright the application, and the application is not limited to following embodiment.It is all that technical scheme is modified or replaced equivalently, and The spirit and scope of technical scheme are not departed from, should all be covered in the protection scope of the application.In the embodiment of the present application Used raw material is commercially available unless otherwise specified.
Comparative example 1
By the mixture of negative electrode active material graphite and Si powder (wherein, the mass percentage of Si powder be 25%), cathode Bonding agent butadiene-styrene rubber, cathode conductive agent conductive carbon black Super P 92:3:5 in mass ratio are uniformly mixed with water is made cathode slurry Material, later according to 121mg/1540mm2Coat weight negative electrode slurry is coated uniformly on positive and negative the two of negative current collector copper foil On face, negative electrode tab is prepared into after 85 DEG C of ovens are dried.The electron scanning micrograph of negative electrode tab is as shown in Figure 3.
Metallic lithium foil is compounded in negative electrode tab by the compound mode of roll-in to get rich lithium cathode sheet is arrived, wherein metal Lithium foil with a thickness of 10 μm.
Comparative example 2
By the mixture of negative electrode active material graphite and Si powder (wherein, the mass percentage of Si powder be 25%), cathode Bonding agent butadiene-styrene rubber, cathode conductive agent conductive carbon black SuperP 92:3:5 in mass ratio are uniformly mixed with water is made cathode slurry Material, later according to 121mg/1540mm2Coat weight negative electrode slurry is coated uniformly on positive and negative the two of negative current collector copper foil On face, initial negative electrode tab is prepared into after 85 DEG C of ovens are dried.
Conductive agent conductive carbon black Super P and bonding agent sodium carboxymethylcellulose 97:3 in mass ratio are mixed with pure water It is even that slurry is made, slurry is coated on the two of initial negative electrode tab using the method that rotary spraying or high pressure painting or centrifugal force spray On face, porous conductive coating is formed after dry, wherein the thickness control of porous conductive coating is at 1 ± 0.5 μm, porous conductive coating Porosity be 42.33%.
Metallic lithium foil is compounded in negative electrode tab by the compound mode of roll-in to get rich lithium cathode sheet is arrived, wherein metal Lithium foil with a thickness of 10 μm.
Embodiment
By negative electrode active material graphite and SiOxThe mixture (weight ratio 7:3) of (0 < x < 2), cathode bonding agent butylbenzene rubber Glue, cathode conductive agent conductive carbon black Super P 92:3:5 in mass ratio are uniformly mixed with water and negative electrode slurry are made, later according to 121mg/1540mm2Coat weight negative electrode slurry is coated uniformly on the tow sides of negative current collector copper foil, by 85 Initial negative electrode tab is prepared into after the drying of DEG C oven.
Polyortho methylaniline (POT), dimethyl amine ethyl ester or poly- two propylene dimethyl ammonium (PDADMA) is dense by 2% respectively Degree is uniformly mixed with pure water is made slurry, is coated on slurry by adjusting the coating speed and coating speed ratio of extrusion coating machine On the two sides of initial negative electrode tab, the porous heat dissipating layer of Examples 1 to 5 is formed after dry in 50 DEG C~90 DEG C temperature ranges.
By further controlling control slurry concentration, drying temperature and coating machine parameter, embodiment 6~11 is prepared Porous heat dissipating layer.
Thickness and the hole coverage rate for controlling porous heat dissipating layer are specifically as shown in table 1.
Metallic lithium foil is compounded in negative electrode tab by the compound mode of roll-in to get rich lithium cathode sheet is arrived, wherein metal Lithium foil with a thickness of 10 μm.
Table 1
Test method:
1, the test of the heating temperature in lithium up process are as follows:
The heating temperature of negative electrode tab uses multichannel temperature logger or thermocouple temperature in the drying shed of low temperature and low humidity in lithium up process Degree meter or infrared thermometer measurement gained, drying shed temperature are 22 DEG C, humidity 1%.Test process are as follows: will be with a thickness of 5 μm Metallic lithium foil is compounded in the negative electrode tab that length is 3m, is wound on the reel of diameter 3cm at once, and the temperature at coiled strip center is detected Variation.
As shown in fig. 6, the temperature change at the negative electrode tab coiled strip center for comparative example 1 and embodiment 2, heating temperature are defined as The peak of temperature in Fig. 6.
2, the test method of the active lithium amount after lithium is mended are as follows:
Active lithium amount will be measured with drainage, will be calculate by the following formula after winding pole piece placement 6 hours:
Wherein, mWater=displaced weight；
Vm=molar volume of gas；
MLiThe molal weight of=Li；
mLi=mend lithium weight.
10 pole pieces are measured in parallel, average value is calculated, obtained data are as shown in table 2.
3, multiplying power test method:
At normal temperature, voltage 4.2V is charged to 0.7C multiplying power, is then 2.5V with 0.5C multiplying power discharging to voltage, at this time Discharge capacity is D1；Voltage 4.2V is charged to 0.7C multiplying power, is then 2.5V with 2C multiplying power discharging to voltage, electric discharge is held at this time Amount is D2.D2/D1 is calculated as 2C high rate performance.
10 pole pieces are measured in parallel, average value is calculated, obtained data are as shown in table 2.
4, coulombic efficiency for the first time:
At normal temperature, voltage 4.2V is charged to 0.3C multiplying power, charging capacity is C0 at this time；With 0.5C multiplying power discharging to electricity 2.5V is pressed, discharge capacity is D0 at this time；Coulombic efficiency=D0/C0 for the first time.
10 pole pieces are measured in parallel, average value is calculated, obtained data are as shown in table 2.
Table 2:
As known from Table 2, embodiment 1-5 is compared with comparative example 1 it is found that embodiments herein, which can reduce pole piece, mends lithium mistake Heating temperature in journey；And embodiment 1-3, in 7, with the increase of heat dissipating layer thickness, heating temperature is declined, active lithium Content increased, but due to the increase without conductive material thickness in heat dissipating layer, electricity while causing heat dissipating layer thickness to increase The high rate performance in pond has a declining tendency.By embodiment 9 it is found that if heat dissipating layer thickness is too small, heat dissipation effect is not significant.
Embodiment 1-5 and comparative example 2 the difference is that material without adsorbable lithium ion in heat dissipating layer, therefore can be effective Raising lithium up process in lithium utilization rate, active lithium amount can be improved；Embodiment 1-5 relative to comparative example 1-2, battery High rate performance does not reduce significantly, therefore under the premise of rationally control heat dissipating layer thickness, cathode pole provided by the invention Piece will not deteriorate battery high rate performance.
By embodiment 6 it is found that influencing the dynamic performance of cathode pole piece if the aperture of porous heat dissipating layer is too small.By Embodiment 9-10 it is found that if the hole coverage rate of porous heat dissipating layer it is too small can not effective auxiliary heat dissipation, while abundance can not be provided Lithium ion tunnel；If the hole coverage rate of porous heat dissipating layer is excessive, heat dissipating layer structure can not be supported, while can not effectively completely cut off Negative electrode active material and metal layer.
It is not for limiting claim, any this field skill although the application is disclosed as above with preferred embodiment Art personnel without departing from the concept of this application, can make several possible variations and modification, therefore the application Protection scope should be subject to the range that the claim of this application is defined.

Claims (12)

1. a kind of negative electrode tab, which is characterized in that including negative current collector, anode active material layer and porous heat dissipating layer,
The anode active material layer is located on the negative current collector,
The porous heat dissipating layer is located in the anode active material layer；
Contain negative electrode active material in the anode active material layer, the negative electrode active material is selected from silicon, tin, silica, oxygen Change tin, silicon and the composite material of carbon, the composite material of tin and carbon, the halide of silicon, the halide of tin, silicon alloy, in tin alloy At least one；
Contain the compound or poly- at least one of structural unit shown in Formulas I, Formula II, formula III in the porous heat dissipating layer Close object；
Wherein, R1、R2It is independently selected from C1~C6Alkyl.
2. negative electrode tab according to claim 1, which is characterized in that the polymer with structural unit shown in Formulas I is selected from such as Polymer shown in Formulas I A；
Wherein, R1、R2It is independently selected from C1~C3Alkyl, 100≤n≤10000.
3. negative electrode tab according to claim 1, which is characterized in that the compound with structural unit shown in Formula II is selected from such as Polymer shown in Formula II A；
Wherein, R1、R2It is independently selected from C1~C3Alkyl, R3Selected from C1~C6Alkylidene, R4Selected from C1~C6Alkyl.
4. negative electrode tab according to claim 1, which is characterized in that the polymer with structural unit shown in formula III is selected from The polymer as shown in formula III A；
Wherein, R1、R2It is independently selected from C1~C3Alkyl, R5、R6It is independently selected from C1~C6Alkylidene, 100≤m≤ 10000。
5. negative electrode tab according to any one of claims 1 to 4, which is characterized in that contain poly- neighbour in the porous heat dissipating layer At least one of methylaniline, poly- two propylene dimethyl ammonium, dimethyl amine ethyl ester.
6. negative electrode tab according to claim 1, which is characterized in that the hole coverage rate of the porous heat dissipating layer be 20%~ 50%.
7. negative electrode tab according to claim 1, which is characterized in that the aperture of the porous heat dissipating layer is 10nm~120nm； Preferably 20nm~90nm.
8. negative electrode tab according to claim 1, which is characterized in that the porous heat dissipating layer with a thickness of 0.5 μm~3.5 μ m。
9. negative electrode tab according to claim 1, which is characterized in that the negative electrode active material further includes graphite, amorphous At least one of carbon.
10. a kind of richness lithium cathode sheet, which is characterized in that contain negative electrode tab according to any one of claims 1 to 9 and lithium metal Layer,
The metallic lithium layer is set on the porous heat dissipating layer.
11. a kind of lithium ion secondary battery, which is characterized in that the lithium ion secondary battery includes as claimed in claim 10 Rich lithium cathode sheet.
12. a kind of preparation method of negative electrode tab as described in any one of claims 1 to 9, which is characterized in that include at least following Step:
The anode active material layer is prepared on the negative current collector；
The compound containing at least one of structural unit shown in Formulas I, Formula II, formula III or polymer are prepared into The solvent of the solution that mass percent concentration is 0.1~20%, the solution is selected from polar solvent, preferably water；
The solution coating is described porous scattered in being formed in the anode active material layer after the solvent evaporation in the solution Thermosphere.
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CN117117183A (en) * 2023-01-03 2023-11-24 荣耀终端有限公司 Negative electrode piece and lithium ion battery
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CN106099041A (en) * 2016-08-26 2016-11-09 深圳博磊达新能源科技有限公司 A kind of lithium titanate composite negative pole pole piece and lithium titanate battery
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