CN115295764B - Negative electrode plate, preparation method thereof and secondary battery - Google Patents
Negative electrode plate, preparation method thereof and secondary battery Download PDFInfo
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- CN115295764B CN115295764B CN202210907036.2A CN202210907036A CN115295764B CN 115295764 B CN115295764 B CN 115295764B CN 202210907036 A CN202210907036 A CN 202210907036A CN 115295764 B CN115295764 B CN 115295764B
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- NIFIFKQPDTWWGU-UHFFFAOYSA-N pyrite Chemical compound [Fe+2].[S-][S-] NIFIFKQPDTWWGU-UHFFFAOYSA-N 0.000 description 1
- 229910052683 pyrite Inorganic materials 0.000 description 1
- 230000034655 secondary growth Effects 0.000 description 1
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- 229910052721 tungsten Inorganic materials 0.000 description 1
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- 239000012498 ultrapure water Substances 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- GPPXJZIENCGNKB-UHFFFAOYSA-N vanadium Chemical compound [V]#[V] GPPXJZIENCGNKB-UHFFFAOYSA-N 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
- 239000011701 zinc Substances 0.000 description 1
- 229910052726 zirconium Inorganic materials 0.000 description 1
Classifications
-
- 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
- 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
- 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
- H01M4/62—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
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Materials Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
本发明属于二次电池技术领域，尤其涉及一种负极极片和二次电池。本发明的负极极片包括负极集流体以及设置于负极集流体至少一表面的膜片层，所述膜片层包括以下重量份数的原料：80～98份硅材料、0.1～5份产气材料、1～10份粘结剂和0.2～8份的导电剂。本发明的一种负极极片，能够有效地控制电极材料在循环过程中的膨胀，控制容量衰减，提高循环稳定性。
The present invention belongs to the technical field of secondary batteries, and in particular, relates to a negative electrode plate and a secondary battery. The negative electrode plate of the present invention includes a negative electrode current collector and a membrane layer disposed on at least one surface of the negative electrode current collector, and the membrane layer includes the following raw materials in parts by weight: 80 to 98 parts of silicon material, 0.1 to 5 parts of gas generating material, 1 to 10 parts of binder and 0.2 to 8 parts of conductive agent. A negative electrode plate of the present invention can effectively control the expansion of electrode materials during the cycle, control capacity attenuation, and improve cycle stability.
Description
Technical Field
The invention belongs to the technical field of secondary batteries, and particularly relates to a negative electrode plate, a preparation method thereof and a secondary battery.
Background
Currently, lithium Ion Batteries (LIBs) are widely used in portable devices and electronic products, however, there are still some problems in the application of electric vehicles and renewable energy storage grids, including energy density, material cost, and use safety. Therefore, it is important to develop a lithium ion battery having high energy density and long cycle life with excellent performance.
Silicon (Si) has an excellent theoretical specific surface area capacity, developed as one of attractive candidate negative electrode materials, and silicon negative electrodes have a very high theoretical capacity (about 4200 mAh/g), about 10 times the current available commercial graphite negative electrode capacity (about 370 mAh/g). Unfortunately, silicon presents a serious inherent problem in the lithiation process/delithiation process. Repeated intercalation and deintercalation of lithium ions easily causes huge volume changes (about 300%) and cracks, resulting in poor electron conductivity and secondary growth of an uncontrollable Solid Electrolyte Interface (SEI) film, which eventually damages the integrity of the battery, resulting in rapid capacity decay.
Carbon-coated silicon is an effective strategy for inhibiting volume expansion of silicon anode materials in lithium ion batteries and improving cycle stability. However, optimization of the carbon/silicon clad material structure and improvement of structural stability and flexibility on the negative electrode sheet level remain a great challenge.
Disclosure of Invention
One of the purposes of the invention is to provide a negative electrode plate which can effectively control the expansion of electrode materials in the circulation process, control the capacity attenuation and improve the circulation stability aiming at the defects of the prior art.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
the negative electrode plate comprises a negative electrode current collector and a membrane layer arranged on at least one surface of the negative electrode current collector, wherein the membrane layer comprises, by weight, 80-98 parts of a silicon material, 0.1-5 parts of a gas generating material, 1-10 parts of a binder and 0.2-8 parts of a conductive agent.
Preferably, the membrane layer comprises an expansion layer arranged on the surface of the negative electrode current collector, a buffer layer arranged on one side of the expansion layer away from the negative electrode current collector, and a protective layer arranged on the buffer layer away from the expansion layer.
Preferably, the thickness of the membrane layer is 0.035-0.95 mm, and the compaction density of the membrane layer is 1.05-1.90 g/cm 3.
Preferably, the pore diameters of the expansion layer, the buffer layer and the protective layer satisfy the following relation K Intumescent layer 50≥K Buffer layer 50≥K protective layer 50,K Intumescent layer 50≤0.035mm,K protective layer 50 >0.
Preferably, the mass ratio of the silicon material in the expansion layer, the buffer layer and the protective layer is 80% -98%, the mass ratio of the gas generating material in the expansion layer, the buffer layer and the protective layer is 0.1% -5%, the mass ratio of the binder in the expansion layer, the buffer layer and the protective layer is 1% -10%, and the mass ratio of the conductive agent in the expansion layer, the buffer layer and the protective layer is 0.2% -8%.
Preferably, the silicon material content in the expansion layer is greater than the silicon material content in the buffer layer, and the silicon material content in the buffer layer is greater than the silicon material content in the protective layer.
Preferably, the gas generating material content in the expansion layer is greater than the gas generating material content in the buffer layer and/or the gas generating material content in the expansion layer is greater than the gas generating material content in the protective layer.
Preferably, the binder content in the expansion layer is greater than the binder content in the buffer layer and/or the binder content in the protective layer is greater than the binder content in the buffer layer.
Preferably, the content of the conductive agent in the expansion layer is greater than the content of the conductive agent in the buffer layer and/or the content of the conductive agent in the expansion layer is greater than the content of the conductive agent in the protective layer.
The second purpose of the invention is to provide a preparation method of the negative electrode plate, aiming at the defects of the prior art, slurries with different silicon material contents and gas generating material contents are respectively prepared, and an expansion layer, a buffer layer and a protection layer are respectively obtained through coating.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
the preparation method of the negative electrode plate comprises the following steps:
Step S1, mixing a silicon material, a gas generating material, a binder and a conductive agent according to a first proportion, adding a solvent and stirring to prepare first negative electrode slurry;
Step S2, coating the first negative electrode slurry on at least one surface of a negative electrode current collector, and drying to form an expansion layer, wherein in step S3, a silicon material, a gas generating material, a binder and a conductive agent are mixed according to a second proportion, and a solvent is added for stirring to prepare a second negative electrode slurry;
S4, coating the second negative electrode slurry on the surface of the expansion layer, and drying to form a buffer layer;
s5, mixing the silicon material, the gas generating material, the binder and the conductive agent according to a third proportion, adding a solvent and stirring to prepare third negative electrode slurry;
And S6, coating the third negative electrode slurry on the surface of the buffer layer, and drying to form a protective layer to obtain the negative electrode plate.
The invention aims to provide a secondary battery which has higher capacity and cycle life, slower capacity attenuation and good cycle stability, and aims to overcome the defects of the prior art.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
A secondary battery comprises the negative electrode plate.
Compared with the prior art, the invention has the beneficial effects that the silicon material is arranged in the pole piece to increase the capacity and the gas production material, so that the pole piece has a certain porosity, space is provided for the volume expansion of the silicon material, the expansion of the electrode material in the circulation process is effectively slowed down, the capacity attenuation is controlled, and the circulation stability is improved.
Drawings
Fig. 1 is a schematic structural view of a negative electrode tab of the present invention.
The cathode current collector comprises 1 of a cathode current collector, 2 of a membrane layer, 21 of an expansion layer, 22 of a buffer layer, 23 of a protective layer, 24 of a pore, 25 of a silicon material.
Detailed Description
The invention will be described in further detail with reference to the following detailed description and the accompanying drawings, but the embodiments of the invention are not limited thereto.
1. The negative pole piece can effectively control the expansion of electrode materials in the circulation process, control the capacity attenuation and improve the circulation stability.
The negative electrode plate comprises a negative electrode current collector 1 and a membrane layer 2 arranged on at least one surface of the negative electrode current collector 1, wherein the membrane layer 2 comprises, by weight, 80-98 parts of a silicon material 25, 0.1-5 parts of a gas generating material, 1-10 parts of a binder and 0.2-8 parts of a conductive agent.
According to the invention, the silicon material 25 is arranged in the pole piece to increase the capacity and the gas production material, so that the pole piece has a certain porosity 24, a space is provided for the volume expansion of the silicon material 25, the expansion of the electrode material in the circulation process is effectively slowed down, the capacity attenuation is controlled, and the circulation stability is improved.
The silicon material 25 contains at least one of a carbon-coated nano or micron silicon material 25, a nano or micron silicon oxide and carbon composite material, a silicon carbon nano or micron wire material and a SiOx (2 > x > 0) carbon nano or micron composite material, further, the silicon material 25 contains at least one of artificial graphite, natural ink, modified graphite, soft carbon and hard carbon, and further, the silicon material 25 contains at least one element of oxygen, lithium, magnesium, sodium, potassium, calcium, beryllium, strontium, zirconium, vanadium, boron, zinc, aluminum, silver and fluorine. The silicon material 25 may be single particles or composite particles, and further, the composite particles are polymerized from a plurality of single particles.
The gas generating material is at least one of ammonium fluoride, ammonium chloride and ammonium nitrate.
The binder is at least one of monomers, polymers and copolymers of acrylonitrile, vinylidene fluoride, sodium carboxymethyl cellulose, methacryloyl, acrylic acid, baamine, acrylamide, amide, imide, acrylic ester, styrene-butadiene rubber, vinyl alcohol, sodium alginate, chitosan, ethylene glycol and the like.
The conductive agent is at least one of conductive carbon black, acetylene black, graphite, graphene, micro-nano fibrous conductive agent and micro-nano tubular conductive agent.
The negative current collector 1 is at least one of copper foil, porous copper foil, foam nickel/copper foil, zinc-plated copper foil, nickel-plated copper foil, carbon-coated copper foil, nickel foil, titanium foil, carbon-containing porous copper foil, and single-metal or multi-metal porous copper foil. Copper foil, zinc-plated, nickel-plated and the like, and carbon-coated copper foil are preferable.
In some embodiments, the membrane layer 2 includes an expansion layer 21 disposed on the surface of the negative electrode current collector 1, a buffer layer 22 disposed on a side of the expansion layer 21 away from the negative electrode current collector 1, and a protective layer 23 disposed on the buffer layer 22 away from the expansion layer 21.
The membrane layer 2 is provided with different expansion layers 21, buffer layers 22 and protective layers 23, so that the respective layers respectively play respective roles, and the three layers are matched and cooperated to obtain the pole piece with higher capacity and smaller expansion, and the pole piece has particularly good electrochemical performance and cycling stability.
In some embodiments, the thickness of the film layer 2 is 0.035-0.95 mm, and the compaction density of the film layer 2 is 1.05-1.90 g/cm 3. The film layer 2 is changed with the thickness of the swelling layer 21, the buffer layer 22 and the protective layer 23, and preferably the compaction density of the film layer 2 is 1.45 to 1.72g/cm 3.
In some embodiments, the pore 24 diameters of the expansion layer 21, the buffer layer 22, and the protective layer 23 satisfy the following relationship K Intumescent layer 2150≥K Buffer layer 2250≥K protective layer 2350,K Intumescent layer 2150≤0.035mm,K protective layer 2350>0.
The expansion layer 21, the buffer layer 22 and the protection layer 23 are all provided with pores 24, and the volume ratio of the pores 24 in the expansion layer 21, the buffer layer 22 and the protection layer 23 is reduced in sequence, the pores 24 are gradually denser in sequence, and conversely, the diameters of the pores 24 of the protection layer 23, the buffer layer 22 and the expansion layer 21 are straighter. The above-mentioned K Intumescent layer 2150 is the pore 24 diameter value corresponding to the cumulative percentage of all the pores 24 in the expansion layer 21 reaching 50%, K Buffer layer 2250 is the pore 24 diameter value corresponding to the cumulative percentage of all the pores 24 in the buffer layer 22 reaching 50%, and K protective layer 2350 is the pore 24 diameter value corresponding to the cumulative percentage of all the pores 24 in the protective layer 23 reaching 50%, and the length unit of the pore 24 diameter may be one of nm and μm, mm, cm, dm, m according to the described suitability.
In some embodiments, the mass ratio of the silicon material 25 in the expansion layer 21, the buffer layer 22 and the protection layer 23 is 80% -98%, the mass ratio of the gas generating material in the expansion layer 21, the buffer layer 22 and the protection layer 23 is 0.1% -5%, the mass ratio of the binder in the expansion layer 21, the buffer layer 22 and the protection layer 23 is 1% -10%, and the mass ratio of the conductive agent in the expansion layer 21, the buffer layer 22 and the protection layer 23 is 0.2% -8%.
In some embodiments, the silicon material 25 content in the expansion layer 21 is greater than the silicon material 25 content in the buffer layer 22, and the silicon material 25 content in the buffer layer 22 is greater than the silicon material 25 content in the protection layer 23.
Further, 35% or more of the mass of silicon in the expansion layer 21 to the mass of the buffer layer 22 to the mass of the protective layer 23 to >0.5% or 85% or more of the mass of silicon material 25 in the expansion layer 21 to the mass of silicon material 25 in the buffer layer 22 to the mass of silicon material 25 in the protective layer 23 to >1.0%.
In some embodiments, the gas generating material content in the expansion layer 21 is greater than the gas generating material content in the buffer layer 22 and/or the gas generating material content in the expansion layer 21 is greater than the gas generating material content in the protective layer 23.
In some embodiments, the binder content in the intumescent layer 21 is greater than the binder content in the buffer layer 22 and/or the binder content in the protective layer 23 is greater than the binder content in the buffer layer 22.
In some embodiments, the amount of conductive agent in the intumescent layer 21 is greater than the amount of conductive agent in the buffer layer 22 and/or the amount of conductive agent in the intumescent layer 21 is greater than the amount of conductive agent in the protective layer 23.
2. The preparation method of the negative electrode plate comprises the following steps:
step S1, mixing a silicon material 25, a gas generating material, a binder and a conductive agent according to a first proportion, adding a solvent and stirring to prepare first negative electrode slurry;
step S2, coating the first negative electrode slurry on at least one surface of the negative electrode current collector 1, and drying to form an expansion layer 21;
step S3, mixing the silicon material 25, the gas generating material, the binder and the conductive agent according to a second proportion, adding a solvent and stirring to prepare second negative electrode slurry;
Step S4, coating the second negative electrode slurry on the surface of the expansion layer 21, and drying to form a buffer layer 22;
step S5, mixing the silicon material 25, the gas generating material, the binder and the conductive agent according to a third proportion, adding a solvent and stirring to prepare third negative electrode slurry;
and S6, coating the third negative electrode slurry on the surface of the buffer layer 22, and drying to form the protective layer 23 to obtain the negative electrode plate.
The preparation method of the negative electrode plate respectively prepares slurries with different silicon material 25 contents and gas generating material contents, and respectively obtains the expansion layer 21, the buffer layer 22 and the protective layer 23 through coating. In the preparation method of the negative electrode plate, the drying temperature is 50-120 ℃ and the drying time is 4-20 hours. The rolling pressure of the tabletting is 0.05-0.55 MPa. Further, the rolling pressure required for the first compression sheet is < the rolling pressure required for the subsequent two compression sheets. The gas generating material comprises, by mass, 2594% -96% of a silicon material, 1.5% -3% of a binder, 1.5% -1.8% of a conductive agent, and 0.7% -1.5% of a gas generating material, wherein the first proportion comprises, by mass, 2596% -97% of a silicon material, 1.2% -1.5% of a binder, 1.1% -1.5% of a conductive agent, and 0.4% -0.6% of a gas generating material, and the third proportion comprises, by mass, 2596% -98% of a silicon material, 1.5% -3% of a binder, 0.6% -0.8% of a conductive agent, and 0.2% -0.3% of a gas generating material. The solvent is one of deionized water, purified water and ultrapure water.
3. A secondary battery has high capacity and cycle life, low capacity fade and good cycle stability.
A secondary battery comprises the negative electrode plate.
The secondary battery comprises a positive plate, a separation film, a negative plate, electrolyte and a shell, wherein the separation film is used for separating the positive plate from the negative plate, the shell is used for packaging the positive plate, the separation film, the negative plate and the electrolyte, and the negative plate is the negative plate.
Positive electrode
The positive electrode sheet comprises a positive electrode current collector and a positive electrode active material layer arranged on at least one surface of the positive electrode current collector, wherein the positive electrode active material layer comprises a positive electrode active material, the positive electrode active material can be a combination of one or more compounds shown by chemical formulas such as Li aNixCoyMzO2-bNb (wherein 0.95-1.2, x >0, y-0, z-0, and x+y+z=1, 0-1, m is selected from one or more combinations of Mn and Al, N is selected from one or more combinations of F, P, S), and the positive electrode active material can also be a combination of one or more compounds including LiCoO2、LiNiO2、LiVO2、LiCrO2、LiMn2O4、LiCoMnO4、Li2NiMn3O8、LiNi0.5Mn1.5O4、LiCoPO4、LiMnPO4、LiFePO4、LiNiPO4、LiCoFSO4、CuS2、FeS2、MoS2、NiS、TiS2 and the like. The positive electrode active material may be further modified, and a method for modifying the positive electrode active material should be known to those skilled in the art, for example, coating, doping, etc. may be used to modify the positive electrode active material, and the material used in the modification may be one or more combinations including but not limited to Al, B, P, zr, si, ti, ge, sn, mg, ce, W, etc. The positive current collector is usually a structure or a part for collecting current, and the positive current collector may be various materials suitable for being used as a positive current collector of a lithium ion battery in the field, for example, the positive current collector may be a metal foil, and the like, and more particularly may include, but is not limited to, an aluminum foil, and the like.
Electrolyte solution
The lithium ion battery also includes an electrolyte comprising an organic solvent, an electrolyte lithium salt, and an additive. The electrolyte lithium salt may be LiPF 6 and/or LiBOB used in the high-temperature electrolyte, at least one of LiBF 4、LiBOB、LiPF6 used in the low-temperature electrolyte, at least one of LiBF 4、LiBOB、LiPF6 and LiTFSI used in the overcharge-preventing electrolyte, or at least one of LiClO 4、LiAsF6、LiCF3SO3、LiN(CF3SO2)2. The organic solvent can be cyclic carbonate, including PC and EC, chain carbonate, including DFC, DMC, EMC, carboxylic ester, including MF, MA, EA, MP, etc. And the additive includes, but is not limited to, at least one of a film forming additive, a conductive additive, a flame retardant additive, an overcharge preventing additive, an additive for controlling the contents of H 2 O and HF in the electrolyte, an additive for improving low temperature performance, and a multifunctional additive.
Preferably, the shell is made of one of stainless steel and aluminum plastic film. More preferably, the housing is an aluminum plastic film.
Example 1
1, Preparing a negative electrode plate:
1.1 a silicon-containing layered negative plate comprises a negative current collector 1 copper foil and a layer of membrane on each of two sides of the copper foil, wherein the membrane comprises a silicon material 25, a binder and a conductive agent.
1.2A preparation method of a silicon-containing layered negative plate comprises the steps of mixing a silicon material 25, a conductive agent, a binder and a gas-generating material, adding deionized water, stirring, pulping to obtain a negative electrode slurry, coating the negative electrode slurry on a copper foil, tabletting, slicing and drying to obtain a copper foil attached with an expansion layer 21, coating the negative electrode slurry on the copper foil, tabletting, slicing and drying to obtain a copper foil attached with the expansion layer 21 and a buffer layer 22, and coating the negative electrode slurry on the copper foil, tabletting, slicing and drying to obtain the copper foil attached with the expansion layer 21, the buffer layer 22 and a protective layer 23 (membrane), namely the silicon-containing layered negative plate.
The drying temperature is 105 ℃ and the drying time is 6h.
The rolling pressure required by the first tabletting is 0.09MPa, and the rolling pressure required by the subsequent two tabletting is 1.65MPa and 1.89MPa respectively.
1.3 A membrane with the thickness of 0.132mm comprises an expansion layer 21, a buffer layer 22 and a protective layer 23, wherein the expansion layer 21, the buffer layer 22 and the protective layer 23 are sequentially and closely contacted and arranged, the expansion layer 21 is nearest to the negative electrode current collector 1, the buffer layer 22 and the protective layer 23 are sequentially far away from the negative electrode current collector 1, and the protective layer 23 is nearest to electrolyte and a separation membrane, as shown in figure 1;
The diameters of pores 24 in the expansion layer 21, the buffer layer 22 and the protection layer 23 are sequentially reduced, the volume ratio of the pores 24 is sequentially reduced, the pores 24 are sequentially more dense, and the diameters of the pores 24 of the protection layer 23, the buffer layer 22 and the expansion layer 21 are sequentially more dilute and larger, so that the requirement that 0.014m is more than or equal to K Intumescent layer 2150≥K Buffer layer 2250≥K protective layer 2350 >0 is met.
The silicon material 25 is single particles and composite particles, the micron silicon oxide and the graphite composite material are mixed to obtain single particles, and a plurality of single particles are polymerized to obtain composite particles;
The mass of the silicon material 25 in the expansion layer 21, the buffer layer 22 and the protection layer 23 is 95.7%, 97% and 97.6%, respectively, wherein the mass of the silicon oxide in each layer of the expansion layer 21, the buffer layer 22 and the protection layer 23 is 16.2%, 12.8% and 3.1% of the mass of the expansion layer 21, the buffer layer 22 and the protection layer 23, respectively.
The adhesive is prepared by mixing polyacrylonitrile and styrene-butadiene latex according to a mass ratio of 1:1, and the adhesive respectively accounts for 1.5%, 1.2% and 1.5% of the mass of each layer of the expansion layer 21, the buffer layer 22 and the protection layer 23;
The gas generating substance is ammonium fluoride, and the ammonium fluoride accounts for 1.5%, 0.5% and 0.2% of the mass of the expansion layer 21, the buffer layer 22 and the protection layer 23 respectively;
The conductive agent is prepared by mixing conductive carbon black and conductive carbon nano tubes according to the mass ratio of 8:2, and the conductive agent respectively accounts for 1.8%, 1.2% and 0.6% of the mass of the expansion layer 21, the buffer layer 22 and the protection layer 23.
2, Preparation of lithium ion battery:
and winding the prepared silicon-containing layered negative plate, the isolating film and the positive plate (containing 96.5% of lithium nickel cobalt manganese oxide LiNi 0.8Co0.1Mn0.1O2 positive active substance) to obtain a battery core, sealing the battery core, packaging the battery core into a battery shell, welding a shell opening, vacuum drying, injecting electrolyte into the battery shell, packaging, standing, forming and separating the battery shell to obtain the lithium ion battery.
The measurement items comprise compaction density and capacity retention rate of the lithium ion battery after 1 circle, 20 circles, 100 circles, 500 circles and 1000 circles of cyclic charge and discharge, and the surface appearance of the membrane after 1000 circles of cyclic charge and discharge is observed by an electron microscope.
Example 2
1, Preparing a negative electrode plate:
1.1 a silicon-containing layered negative plate comprises a negative current collector 1 copper foil and a layer of membrane on each of two sides of the copper foil, wherein the membrane comprises a silicon material 25, a binder and a conductive agent.
1.2A preparation method of a silicon-containing layered negative plate comprises the steps of mixing a silicon material 25, a conductive agent, a binder and a gas-generating material, adding deionized water, stirring, pulping to obtain a negative electrode slurry, coating the negative electrode slurry on a copper foil, tabletting, slicing and drying to obtain a copper foil attached with an expansion layer 21, coating the negative electrode slurry on the copper foil, tabletting, slicing and drying to obtain a copper foil attached with the expansion layer 21 and a buffer layer 22, and coating the negative electrode slurry on the copper foil, tabletting, slicing and drying to obtain the copper foil attached with the expansion layer 21, the buffer layer 22 and a protective layer 23 (membrane), namely the silicon-containing layered negative plate.
The drying temperature is 105 ℃ and the drying time is 6h.
The rolling pressure required by the first tabletting is 0.09MPa, and the rolling pressure required by the subsequent two tabletting is 1.65MPa and 1.89MPa respectively.
1.3 A membrane with the thickness of 0.136mm comprises an expansion layer 21, a buffer layer 22 and a protective layer 23, wherein the expansion layer 21, the buffer layer 22 and the protective layer 23 are sequentially and closely contacted and arranged, the expansion layer 21 is nearest to the negative electrode current collector 1, the buffer layer 22 and the protective layer 23 are sequentially far away from the negative electrode current collector 1, and the protective layer 23 is nearest to electrolyte and a separation membrane;
The diameters of pores 24 in the expansion layer 21, the buffer layer 22 and the protection layer 23 are sequentially reduced, the volume ratio of the pores 24 is sequentially reduced, the pores 24 are sequentially more dense, and the diameters of the pores 24 of the protection layer 23, the buffer layer 22 and the expansion layer 21 are sequentially more dilute and larger, so that the requirement that 0.014m is more than or equal to K Intumescent layer 2150≥K Buffer layer 2250≥K protective layer 2350 >0 is met.
The silicon material 25 is single particles and composite particles, the micron silicon oxide and the graphite composite material are mixed to obtain single particles, and a plurality of single particles are polymerized to obtain composite particles;
The silicon material 25 is 95.8%, 97.2% and 97% of the mass of the expansion layer 21, the buffer layer 22 and the protective layer 23, wherein the silicon oxide mass of each layer of the expansion layer 21, the buffer layer 22 and the protective layer 23 respectively accounts for 15.8%, 12.7% and 2.9% of the mass of the expansion layer 21, the buffer layer 22 and the protective layer 23.
The adhesive is prepared by mixing polyacrylonitrile and styrene-butadiene latex according to a mass ratio of 1:1, and the adhesive respectively accounts for 2.0%, 1.2% and 2.0% of the mass of each layer of the expansion layer 21, the buffer layer 22 and the protection layer 23;
The gas generating material is ammonium fluoride, and the ammonium fluoride accounts for 0.7%, 0.4% and 0.2% of the mass of the expansion layer 21, the buffer layer 22 and the protection layer 23 respectively;
The conductive agent is prepared by mixing conductive carbon black and conductive carbon nano tubes according to the mass ratio of 8:2, and the conductive agent respectively accounts for 1.5%, 1.2% and 0.8% of the mass of the expansion layer 21, the buffer layer 22 and the protection layer 23.
2, Preparation of lithium ion battery:
Winding a silicon-containing layered negative plate, a separation film and a positive plate (containing 96.5% of lithium nickel cobalt manganese oxide (LiNi 0.8Co0.1Mn0.1O2 positive active substance)) to obtain a battery core, sealing the battery core by a film, packaging a battery shell of the battery core, welding a shell opening, vacuum drying, injecting electrolyte into the battery shell, packaging, standing, forming and separating the battery shell to obtain the lithium ion battery.
The measurement items comprise compaction density and capacity retention rate of the lithium ion battery after 1 circle, 20 circles, 100 circles, 500 circles and 1000 circles of cyclic charge and discharge, and the surface appearance of the membrane after 1000 circles of cyclic charge and discharge is observed by an electron microscope.
Example 3
1 Silicon-containing layered negative plate:
1.1 a silicon-containing layered negative plate comprises a negative current collector 1 copper foil and a layer of membrane on each of two sides of the copper foil, wherein the membrane comprises a silicon material 25, a binder and a conductive agent.
1.2A preparation method of a silicon-containing layered negative plate comprises the steps of mixing a silicon material 25, a conductive agent, a binder and a gas-generating material, adding deionized water, stirring, pulping to obtain a negative electrode slurry, coating the negative electrode slurry on a copper foil, tabletting, slicing and drying to obtain a copper foil attached with an expansion layer 21, coating the negative electrode slurry on the copper foil, tabletting, slicing and drying to obtain a copper foil attached with the expansion layer 21 and a buffer layer 22, and coating the negative electrode slurry on the copper foil, tabletting, slicing and drying to obtain the copper foil attached with the expansion layer 21, the buffer layer 22 and a protective layer 23 (membrane), namely the silicon-containing layered negative plate.
The drying temperature is 105 ℃ and the drying time is 6h.
The rolling pressure required by the first tabletting is 0.09MPa, and the rolling pressure required by the subsequent two tabletting is 1.65MPa and 1.89MPa respectively.
1.3 A membrane thickness is 0.137mm, the membrane comprises an expansion layer 21, a buffer layer 22 and a protective layer 23, the expansion layer 21, the buffer layer 22 and the protective layer 23 are sequentially and closely contacted and arranged, the expansion layer 21 is nearest to the negative electrode current collector 1, the buffer layer 22 and the protective layer 23 are sequentially far away from the negative electrode current collector 1, and the protective layer 23 is nearest to electrolyte and a separation membrane;
The diameters of pores 24 in the expansion layer 21, the buffer layer 22 and the protection layer 23 are sequentially reduced, the volume ratio of the pores 24 is sequentially reduced, the pores 24 are sequentially more dense, and the diameters of the pores 24 of the protection layer 23, the buffer layer 22 and the expansion layer 21 are sequentially more dilute and larger, so that the requirement that 0.014m is more than or equal to K Intumescent layer 2150≥K Buffer layer 2250≥K protective layer 2350 >0 is met.
The silicon material 25 is single particles and composite particles, the micron silicon oxide and the graphite composite material are mixed to obtain single particles, and a plurality of single particles are polymerized to obtain composite particles;
The silicon material 25 is 95.2%, 96.8% and 96.5% of the mass of the expansion layer 21, the buffer layer 22 and the protective layer 23, wherein the silicon oxide mass of each layer of the expansion layer 21, the buffer layer 22 and the protective layer 23 respectively accounts for 15.5%, 12.7% and 2.8% of the mass of the expansion layer 21, the buffer layer 22 and the protective layer 23.
The adhesive is prepared by mixing polyacrylonitrile and styrene-butadiene latex according to a mass ratio of 1:1, and the adhesive respectively accounts for 2.5%, 1.5% and 2.5% of the mass of each layer of the expansion layer 21, the buffer layer 22 and the protection layer 23;
the gas generating material is ammonium fluoride, and the ammonium fluoride accounts for 0.8%, 0.5% and 0.2% of the mass of the expansion layer 21, the buffer layer 22 and the protection layer 23 respectively;
The conductive agent is prepared by mixing conductive carbon black and conductive carbon nano tubes according to the mass ratio of 8:2, and the conductive agent respectively accounts for 1.8%, 1.2% and 0.6% of the mass of the expansion layer 21, the buffer layer 22 and the protection layer 23.
2, Preparation of lithium ion battery:
Winding a silicon-containing layered negative plate, a separation film and a positive plate (containing 96.5% of lithium nickel cobalt manganese oxide (LiNi 0.8Co0.1Mn0.1O2 positive active substance)) to obtain a battery core, sealing the battery core by a film, packaging a battery shell of the battery core, welding a shell opening, vacuum drying, injecting electrolyte into the battery shell, packaging, standing, forming and separating the battery shell to obtain the lithium ion battery.
The measurement items comprise compaction density and capacity retention rate of the lithium ion battery after 1 circle, 20 circles, 100 circles, 500 circles and 1000 circles of cyclic charge and discharge, and the surface appearance of the membrane after 1000 circles of cyclic charge and discharge is observed by an electron microscope.
Example 4
1 Silicon-containing layered negative plate:
1.1 a silicon-containing layered negative plate comprises a negative current collector 1 copper foil and a layer of membrane on each of two sides of the copper foil, wherein the membrane comprises a silicon material 25, a binder and a conductive agent.
1.2A preparation method of a silicon-containing layered negative plate comprises the steps of mixing a silicon material 25, a conductive agent, a binder and a gas-generating material, adding deionized water, stirring, pulping to obtain a negative electrode slurry, coating the negative electrode slurry on a copper foil, tabletting, slicing and drying to obtain a copper foil attached with an expansion layer 21, coating the negative electrode slurry on the copper foil, tabletting, slicing and drying to obtain a copper foil attached with the expansion layer 21 and a buffer layer 22, and coating the negative electrode slurry on the copper foil, tabletting, slicing and drying to obtain the copper foil attached with the expansion layer 21, the buffer layer 22 and a protective layer 23 (membrane), namely the silicon-containing layered negative plate.
The drying temperature is 105 ℃ and the drying time is 6h.
The rolling pressure required by the first tabletting is 0.09MPa, and the rolling pressure required by the subsequent two tabletting is 1.65MPa and 1.89MPa respectively.
1.3 A membrane thickness is 0.143mm, the membrane comprises an expansion layer 21, a buffer layer 22 and a protective layer 23, the expansion layer 21, the buffer layer 22 and the protective layer 23 are sequentially and closely contacted and arranged, the expansion layer 21 is nearest to the negative electrode current collector 1, the buffer layer 22 and the protective layer 23 are sequentially far away from the negative electrode current collector 1, and the protective layer 23 is nearest to electrolyte and a separation membrane;
The diameters of pores 24 in the expansion layer 21, the buffer layer 22 and the protection layer 23 are sequentially reduced, the volume ratio of the pores 24 is sequentially reduced, the pores 24 are sequentially more dense, and the diameters of the pores 24 of the protection layer 23, the buffer layer 22 and the expansion layer 21 are sequentially more dilute and larger, so that the requirement that 0.014m is more than or equal to K Intumescent layer 2150≥K Buffer layer 2250≥K protective layer 2350 >0 is met.
The silicon material 25 is single particles and composite particles, the micron silicon oxide and the graphite composite material are mixed to obtain single particles, and a plurality of single particles are polymerized to obtain composite particles;
The silicon material 25 is 94.7%, 96.8% and 96% of the mass of the expansion layer 21, the buffer layer 22 and the protective layer 23, wherein the silicon oxide mass of each layer of the expansion layer 21, the buffer layer 22 and the protective layer 23 respectively accounts for 14.7%, 12.1% and 2.5% of the mass of the expansion layer 21, the buffer layer 22 and the protective layer 23.
The adhesive is prepared by mixing polyacrylonitrile and styrene-butadiene latex according to a mass ratio of 1:1, and the adhesive respectively accounts for 3.0%, 1.5% and 3.0% of the mass of each layer of the expansion layer 21, the buffer layer 22 and the protection layer 23;
the gas generating material is ammonium fluoride, and the ammonium fluoride accounts for 0.8%, 0.5% and 0.2% of the mass of the expansion layer 21, the buffer layer 22 and the protection layer 23 respectively;
The conductive agent is prepared by mixing conductive carbon black and conductive carbon nano tubes according to the mass ratio of 8:2, and the conductive agent respectively accounts for 1.5%, 1.2% and 0.8% of the mass of the expansion layer 21, the buffer layer 22 and the protection layer 23.
2, Preparation of lithium ion battery:
Winding a silicon-containing layered negative plate, a separation film and a positive plate (containing 96.5% of lithium nickel cobalt manganese oxide (LiNi 0.8Co0.1Mn0.1O2 positive active substance)) to obtain a battery core, sealing the battery core by a film, packaging a battery shell of the battery core, welding a shell opening, vacuum drying, injecting electrolyte into the battery shell, packaging, standing, forming and separating the battery shell to obtain the lithium ion battery.
The measurement items comprise compaction density and capacity retention rate of the lithium ion battery after 1 circle, 20 circles, 100 circles, 500 circles and 1000 circles of cyclic charge and discharge, and the surface appearance of the membrane after 1000 circles of cyclic charge and discharge is observed by an electron microscope.
Example 5
1 Silicon-containing layered negative plate:
1.1 a silicon-containing layered negative plate comprises a negative current collector 1 copper foil and a layer of membrane on each of two sides of the copper foil, wherein the membrane comprises a silicon material 25, a binder and a conductive agent.
1.2A preparation method of a silicon-containing layered negative plate comprises the steps of mixing a silicon material 25, a conductive agent, a binder and a gas-generating material, adding deionized water, stirring, pulping to obtain a negative electrode slurry, coating the negative electrode slurry on a copper foil, tabletting, slicing and drying to obtain a copper foil attached with an expansion layer 21, coating the negative electrode slurry on the copper foil, tabletting, slicing and drying to obtain a copper foil attached with the expansion layer 21 and a buffer layer 22, and coating the negative electrode slurry on the copper foil, tabletting, slicing and drying to obtain the copper foil attached with the expansion layer 21, the buffer layer 22 and a protective layer 23 (membrane), namely the silicon-containing layered negative plate.
The drying temperature was 85 ℃ and the drying time was 12h.
The rolling pressure required by the first tabletting is 0.13MPa, and the rolling pressure required by the subsequent two tabletting is 1.85MPa and 1.95MPa respectively.
1.3 A membrane with the thickness of 0.119mm comprises an expansion layer 21, a buffer layer 22 and a protective layer 23, wherein the expansion layer 21, the buffer layer 22 and the protective layer 23 are sequentially and closely contacted and arranged, the expansion layer 21 is nearest to the negative electrode current collector 1, the buffer layer 22 and the protective layer 23 are sequentially far away from the negative electrode current collector 1, and the protective layer 23 is nearest to electrolyte and a separation membrane;
The diameters of pores 24 in the expansion layer 21, the buffer layer 22 and the protection layer 23 are sequentially reduced, the volume ratio of the pores 24 is sequentially reduced, the pores 24 are sequentially more dense, and the diameters of the pores 24 of the protection layer 23, the buffer layer 22 and the expansion layer 21 are sequentially more dilute and larger, so that the requirement that 0.018m is more than or equal to K Intumescent layer 2150≥K Buffer layer 2250≥K protective layer 2350 >0 is met.
The silicon material 25 is single particles and composite particles, the carbon-coated micron silicon material 25 is mixed with the graphite composite material to obtain single particles, and a plurality of single particles are polymerized to obtain composite particles;
The silicon material 25 is 95.7%, 97% and 97.6% of the mass of the expansion layer 21, the buffer layer 22 and the protective layer 23, wherein the silicon oxide mass of each layer of the expansion layer 21, the buffer layer 22 and the protective layer 23 respectively accounts for 15.6%, 12.4% and 3.0% of the mass of the expansion layer 21, the buffer layer 22 and the protective layer 23.
The adhesive is prepared by mixing polyacrylonitrile and polyvinylidene fluoride according to a mass ratio of 1:1, and the adhesive respectively accounts for 1.5%, 1.2% and 1.5% of the mass of each of the three layers of the expansion layer 21, the buffer layer 22 and the protection layer 23;
The gas generating material is ammonium fluoride, and the ammonium fluoride accounts for 1%, 0.6% and 0.3% of the mass of the expansion layer 21, the buffer layer 22 and the protection layer 23 respectively;
the conductive agent is prepared by mixing acetylene black and conductive carbon nano tubes according to the mass ratio of 8:2, and the conductive agent respectively accounts for 1.8%, 1.2% and 0.6% of the mass of the expansion layer 21, the buffer layer 22 and the protection layer 23.
Preparation of a lithium ion battery:
Winding a silicon-containing layered negative plate, a separation film and a positive plate (containing 96.5% of lithium iron phosphate LiFePO 4 positive active substances) to obtain a battery core, sealing the battery core by a film, packaging the battery core, welding a shell opening, vacuum drying, injecting electrolyte into the battery shell, packaging, standing, forming and separating to obtain the lithium ion battery.
The measurement items comprise compaction density and capacity retention rate of the lithium ion battery after 1 circle, 20 circles, 100 circles, 500 circles and 1000 circles of cyclic charge and discharge, and the surface appearance of the membrane after 1000 circles of cyclic charge and discharge is observed by an electron microscope.
Example 6
1 Silicon-containing layered negative plate:
1.1 a silicon-containing layered negative plate comprises a negative current collector 1 copper foil and a layer of membrane on each of two sides of the copper foil, wherein the membrane comprises a silicon material 25, a binder and a conductive agent.
1.2A preparation method of a silicon-containing layered negative plate comprises the steps of mixing a silicon material 25, a conductive agent, a binder and a gas-generating material, adding deionized water, stirring, pulping to obtain a negative electrode slurry, coating the negative electrode slurry on a copper foil, tabletting, slicing and drying to obtain a copper foil attached with an expansion layer 21, coating the negative electrode slurry on the copper foil, tabletting, slicing and drying to obtain a copper foil attached with the expansion layer 21 and a buffer layer 22, and coating the negative electrode slurry on the copper foil, tabletting, slicing and drying to obtain the copper foil attached with the expansion layer 21, the buffer layer 22 and a protective layer 23 (membrane), namely the silicon-containing layered negative plate.
The drying temperature is 85 ℃ and the drying time is 12h.
The rolling pressure required by the first tabletting is 0.13MPa, and the rolling pressure required by the subsequent two tabletting is 1.85MPa and 1.95MPa respectively.
1.3 A membrane with the thickness of 0.117mm comprises an expansion layer 21, a buffer layer 22 and a protective layer 23, wherein the expansion layer 21, the buffer layer 22 and the protective layer 23 are sequentially and closely contacted and arranged, the expansion layer 21 is nearest to the negative electrode current collector 1, the buffer layer 22 and the protective layer 23 are sequentially far away from the negative electrode current collector 1, and the protective layer 23 is nearest to electrolyte and a separation membrane;
The diameters of pores 24 in the expansion layer 21, the buffer layer 22 and the protection layer 23 are sequentially reduced, the volume ratio of the pores 24 is sequentially reduced, the pores 24 are sequentially more dense, and the diameters of the pores 24 of the protection layer 23, the buffer layer 22 and the expansion layer 21 are sequentially more dilute and larger, so that the requirement that 0.018m is more than or equal to K Intumescent layer 2150≥K Buffer layer 2250≥K protective layer 2350 >0 is met.
The silicon material 25 is single particles and composite particles, the micron silicon oxide and the graphite composite material are mixed to obtain single particles, and a plurality of single particles are polymerized to obtain composite particles;
The silicon material 25 is 95.2%, 97% and 97.1% of the mass of the expansion layer 21, the buffer layer 22 and the protective layer 23, wherein the silicon oxide mass of each layer of the expansion layer 21, the buffer layer 22 and the protective layer 23 respectively accounts for 15.5%, 12.5% and 2.8% of the mass of the expansion layer 21, the buffer layer 22 and the protective layer 23.
The adhesive is prepared by mixing polyacrylonitrile and polyvinylidene fluoride according to a mass ratio of 1:1, and the adhesive respectively accounts for 2%, 1.2% and 2% of the mass of each of the three layers of the expansion layer 21, the buffer layer 22 and the protection layer 23;
The gas generating material is ammonium fluoride, and the ammonium fluoride accounts for 1%, 0.6% and 0.3% of the mass of the expansion layer 21, the buffer layer 22 and the protection layer 23 respectively;
the conductive agent is prepared by mixing acetylene black and conductive carbon nano tubes according to the mass ratio of 8:2, and the conductive agent respectively accounts for 1.8%, 1.2% and 0.6% of the mass of the expansion layer 21, the buffer layer 22 and the protection layer 23.
2, Preparation of lithium ion battery:
Winding a silicon-containing layered negative plate, a separation film and a positive plate (containing 96.5% of lithium iron phosphate LiFePO 4 positive active substances) to obtain a battery core, sealing the battery core by a film, packaging the battery core, welding a shell opening, vacuum drying, injecting electrolyte into the battery shell, packaging, standing, forming and separating to obtain the lithium ion battery.
The measurement items comprise compaction density and capacity retention rate of the lithium ion battery after 1 circle, 20 circles, 100 circles, 500 circles and 1000 circles of cyclic charge and discharge, and the surface appearance of the membrane after 1000 circles of cyclic charge and discharge is observed by an electron microscope.
Example 7
1 Silicon-containing layered negative plate:
1.1 a silicon-containing layered negative plate comprises a negative current collector 1 copper foil and a layer of membrane on each of two sides of the copper foil, wherein the membrane comprises a silicon material 25, a binder and a conductive agent.
1.2A preparation method of a silicon-containing layered negative plate comprises the steps of mixing a silicon material 25, a conductive agent, a binder and a gas-generating material, adding deionized water, stirring, pulping to obtain a negative electrode slurry, coating the negative electrode slurry on a copper foil, tabletting, slicing and drying to obtain a copper foil attached with an expansion layer 21, coating the negative electrode slurry on the copper foil, tabletting, slicing and drying to obtain a copper foil attached with the expansion layer 21 and a buffer layer 22, and coating the negative electrode slurry on the copper foil, tabletting, slicing and drying to obtain the copper foil attached with the expansion layer 21, the buffer layer 22 and a protective layer 23 (membrane), namely the silicon-containing layered negative plate.
The drying temperature is 85 ℃ and the drying time is 12h.
The rolling pressure required by the first tabletting is 0.13MPa, and the rolling pressure required by the subsequent two tabletting is 1.85MPa and 1.95MPa respectively.
1.3 A membrane thickness is 0.127mm, the membrane comprises an expansion layer 21, a buffer layer 22 and a protective layer 23, the expansion layer 21, the buffer layer 22 and the protective layer 23 are sequentially and closely contacted and arranged, the expansion layer 21 is nearest to the negative electrode current collector 1, the buffer layer 22 and the protective layer 23 are sequentially far away from the negative electrode current collector 1, and the protective layer 23 is nearest to electrolyte and a separation membrane;
The diameters of pores 24 in the expansion layer 21, the buffer layer 22 and the protection layer 23 are sequentially reduced, the volume ratio of the pores 24 is sequentially reduced, the pores 24 are sequentially more dense, and the diameters of the pores 24 of the protection layer 23, the buffer layer 22 and the expansion layer 21 are sequentially more dilute and larger, so that the requirement that 0.018m is more than or equal to K Intumescent layer 2150≥K Buffer layer 2250≥K protective layer 2350 >0 is met.
The silicon material 25 is single particles and composite particles, the micron silicon oxide and the graphite composite material are mixed to obtain single particles, and a plurality of single particles are polymerized to obtain composite particles;
The silicon material 25 is 94.7%, 96.7% and 96.6% of the mass of the expansion layer 21, the buffer layer 22 and the protective layer 23, wherein the silicon oxide mass of each layer of the expansion layer 21, the buffer layer 22 and the protective layer 23 respectively accounts for 15.3%, 12.2% and 2.5% of the mass of the expansion layer 21, the buffer layer 22 and the protective layer 23.
The adhesive is prepared by mixing polyacrylonitrile and polyvinylidene fluoride according to a mass ratio of 1:1, and the adhesive respectively accounts for 2.5%, 1.5% and 2.5% of the mass of each of the three layers of the expansion layer 21, the buffer layer 22 and the protection layer 23;
The gas generating material is ammonium fluoride, and the ammonium fluoride accounts for 1%, 0.6% and 0.3% of the mass of the expansion layer 21, the buffer layer 22 and the protection layer 23 respectively;
the conductive agent is prepared by mixing acetylene black and conductive carbon nano tubes according to the mass ratio of 8:2, and the conductive agent respectively accounts for 1.8%, 1.2% and 0.6% of the mass of the expansion layer 21, the buffer layer 22 and the protection layer 23.
2, Preparation of lithium ion battery:
Winding a silicon-containing layered negative plate, a separation film and a positive plate (containing 96.5% of lithium iron phosphate LiFePO 4 positive active substances) to obtain a battery core, sealing the battery core by a film, packaging the battery core, welding a shell opening, vacuum drying, injecting electrolyte into the battery shell, packaging, standing, forming and separating to obtain the lithium ion battery.
The measurement items comprise compaction density and capacity retention rate of the lithium ion battery after 1 circle, 20 circles, 100 circles, 500 circles and 1000 circles of cyclic charge and discharge, and the surface appearance of the membrane after 1000 circles of cyclic charge and discharge is observed by an electron microscope.
Example 8:
1 silicon-containing layered negative plate:
1.1 a silicon-containing layered negative plate comprises a negative current collector 1 copper foil and a layer of membrane on each of two sides of the copper foil, wherein the membrane comprises a silicon material 25, a binder and a conductive agent.
1.2A preparation method of a silicon-containing layered negative plate comprises the steps of mixing a silicon material 25, a conductive agent, a binder and a gas-generating material, adding deionized water, stirring, pulping to obtain a negative electrode slurry, coating the negative electrode slurry on a copper foil, tabletting, slicing and drying to obtain a copper foil attached with an expansion layer 21, coating the negative electrode slurry on the copper foil, tabletting, slicing and drying to obtain a copper foil attached with the expansion layer 21 and a buffer layer 22, and coating the negative electrode slurry on the copper foil, tabletting, slicing and drying to obtain the copper foil attached with the expansion layer 21, the buffer layer 22 and a protective layer 23 (membrane), namely the silicon-containing layered negative plate.
The drying temperature is 85 ℃ and the drying time is 12h.
The rolling pressure required by the first tabletting is 0.13MPa, and the rolling pressure required by the subsequent two tabletting is 1.85MPa and 1.95MPa respectively.
1.3 A membrane thickness is 0.115mm, the membrane comprises an expansion layer 21, a buffer layer 22 and a protective layer 23, the expansion layer 21, the buffer layer 22 and the protective layer 23 are sequentially and closely contacted and arranged, the expansion layer 21 is nearest to the negative electrode current collector 1, the buffer layer 22 and the protective layer 23 are sequentially far away from the negative electrode current collector 1, and the protective layer 23 is nearest to electrolyte and a separation membrane;
The diameters of pores 24 in the expansion layer 21, the buffer layer 22 and the protection layer 23 are sequentially reduced, the volume ratio of the pores 24 is sequentially reduced, the pores 24 are sequentially more dense, and the diameters of the pores 24 of the protection layer 23, the buffer layer 22 and the expansion layer 21 are sequentially more dilute and larger, so that the requirement that 0.018m is more than or equal to K Intumescent layer 2150≥K Buffer layer 2250≥K protective layer 2350 >0 is met.
The silicon material 25 is single particles and composite particles, the micron silicon oxide and the graphite composite material are mixed to obtain single particles, and a plurality of single particles are polymerized to obtain composite particles;
The silicon material 25 is 94.2%, 96.7% and 96.1% of the mass of the expansion layer 21, the buffer layer 22 and the protective layer 23, wherein the silicon oxide mass of each layer of the expansion layer 21, the buffer layer 22 and the protective layer 23 respectively accounts for 15.1%, 12.1% and 2.3% of the mass of the expansion layer 21, the buffer layer 22 and the protective layer 23.
The adhesive is prepared by mixing polyacrylonitrile and polyvinylidene fluoride according to a mass ratio of 1:1, and the adhesive respectively accounts for 3%, 1.5% and 3% of the mass of each of the three layers of the expansion layer 21, the buffer layer 22 and the protection layer 23;
The gas generating material is ammonium fluoride, and the ammonium fluoride accounts for 1%, 0.6% and 0.3% of the mass of the expansion layer 21, the buffer layer 22 and the protection layer 23 respectively;
the conductive agent is prepared by mixing acetylene black and conductive carbon nano tubes according to the mass ratio of 8:2, and the conductive agent respectively accounts for 1.8%, 1.2% and 0.6% of the mass of the expansion layer 21, the buffer layer 22 and the protection layer 23.
2, Preparation of lithium ion battery:
Winding a silicon-containing layered negative plate, a separation film and a positive plate (containing 96.5% of lithium iron phosphate LiFePO 4 positive active substances) to obtain a battery core, sealing the battery core by a film, packaging the battery core, welding a shell opening, vacuum drying, injecting electrolyte into the battery shell, packaging, standing, forming and separating to obtain the lithium ion battery.
The measurement items comprise compaction density and capacity retention rate of the lithium ion battery after 1 circle, 20 circles, 100 circles, 500 circles and 1000 circles of cyclic charge and discharge, and the surface appearance of the membrane after 1000 circles of cyclic charge and discharge is observed by an electron microscope.
Comparative example 1:
1, preparation of a silicon-containing negative plate:
1.1 mechanically stirring and mixing 0.25kg of micrometer silicon oxide and 4.75kg of graphite to obtain a silicon material 25, and preparing a silicon-containing negative electrode sheet, wherein the silicon material 25, a binder (the binder prepared in the above example 2) and a conductive agent (the conductive agent prepared in the above example 2) are mixed according to a mass ratio of 96.5:2.5:1 to obtain uniform slurry, the slurry is uniformly coated on a copper foil, the copper foil is rolled and pressed under 1.89MPa, sliced and dried under 105 ℃ for 6 hours to obtain a 0.128mm thick one-layer film, and the two sides of the silicon-containing negative electrode sheet are respectively provided with one-layer film.
2, Preparation of lithium ion battery:
And 2.1, winding a silicon-containing layered negative plate, a separation film and a positive plate (containing 97.5% of lithium nickel cobalt manganese oxide LiNi 0.8Co0.1Mn0.1O2 positive electrode active substance) to obtain a battery cell, sealing the battery cell by using a film, packaging a battery shell of the battery cell, welding a shell opening, vacuum drying, injecting electrolyte into the battery shell, packaging, standing, forming and separating the battery shell to obtain the lithium ion battery.
The measurement items comprise compaction density and capacity retention rate of the lithium ion battery after 1 circle, 20 circles, 100 circles, 500 circles and 1000 circles of cyclic charge and discharge, and the surface appearance of the membrane after 1000 circles of cyclic charge and discharge is observed by an electron microscope.
Comparative example 2:
1, preparation of a silicon-containing negative plate:
1.1 mechanically stirring and mixing 0.25kg of micrometer silicon oxide and 4.75kg of graphite to obtain a silicon material 25, and preparing a silicon-containing negative electrode sheet, wherein the silicon material 25, a binder (the binder prepared in the above example 2) and a conductive agent (the conductive agent prepared in the above example 2) are mixed according to a mass ratio of 97:2.0:1.0 to obtain uniform slurry, the slurry is uniformly coated on a copper foil, the copper foil is rolled and pressed under 1.89MPa, sliced and dried under 105 ℃ for 6 hours to obtain a layer of film with a thickness of 0.123mm, and the two sides of the silicon-containing negative electrode sheet are respectively provided with a layer of film.
2, Preparation of lithium ion battery:
And 2.1, winding a silicon-containing layered negative plate, a separation film and a positive plate (containing 97.5% of lithium nickel cobalt manganese oxide LiNi 0.8Co0.1Mn0.1O2 positive electrode active substance) to obtain a battery cell, sealing the battery cell by using a film, packaging a battery shell of the battery cell, welding a shell opening, vacuum drying, injecting electrolyte into the battery shell, packaging, standing, forming and separating the battery shell to obtain the lithium ion battery.
The measurement items comprise compaction density and capacity retention rate of the lithium ion battery after 1 circle, 20 circles, 100 circles, 500 circles and 1000 circles of cyclic charge and discharge, and the surface appearance of the membrane after 1000 circles of cyclic charge and discharge is observed by an electron microscope.
Comparative example 3
1, Preparation of a silicon-containing negative plate:
1.1 mechanically stirring and mixing 0.15kg of carbon-coated micron silicon material 25 and 4.85kg of graphite to obtain silicon material 25, and preparing a silicon-containing negative electrode sheet, wherein the silicon material 25, a binder (the binder prepared in the above example 6) and a conductive agent (the conductive agent prepared in the above example 6) are mixed according to a mass ratio of 96.5:2.0:1.5 to obtain uniform slurry, the slurry is uniformly coated on a copper foil, the copper foil is pressed into a sheet under 1.95MPa, the sheet is sliced, and the sheet is dried at 85 ℃ for 12 hours to obtain a layer of film with a thickness of 0.154mm, and the two sides of the silicon-containing negative electrode sheet are respectively provided with a layer of film.
2, Preparation of lithium ion battery:
And 2.1, winding a silicon-containing layered negative plate, a separation film and a positive plate (containing 97.5% of lithium iron phosphate LiFePO 4 positive active substances) to obtain a battery core, sealing the battery core by a film, packaging a battery shell of the battery core, welding a shell opening, vacuum drying, injecting electrolyte into the battery shell, packaging, standing, forming and separating to obtain the lithium ion battery.
The measurement items comprise compaction density and capacity retention rate of the lithium ion battery after 1 circle, 20 circles, 100 circles, 500 circles and 1000 circles of cyclic charge and discharge, and the surface appearance of the membrane after 1000 circles of cyclic charge and discharge is observed by an electron microscope.
Comparative example 4:
1, preparation of a silicon-containing negative plate:
1.1 mechanically stirring and mixing 0.15kg of carbon-coated micron silicon material 25 and 4.85kg of graphite to obtain silicon material 25, and preparing a silicon-containing negative electrode sheet, wherein the silicon material 25, a binder (the binder prepared in the above example 6) and a conductive agent (the conductive agent prepared in the above example 6) are mixed according to a mass ratio of 97:2.0:1.0 to obtain uniform slurry, the slurry is uniformly coated on copper foil, the copper foil is rolled under 1.95MPa, pressed into tablets, sliced and dried under 85 ℃ for 12 hours to obtain a layer of film with a thickness of 0.152mm, and the two sides of the silicon-containing negative electrode sheet are respectively provided with a layer of film.
2, Preparation of lithium ion battery:
And 2.1, winding a silicon-containing layered negative plate, a separation film and a positive plate (containing 97.5% of lithium iron phosphate LiFePO 4 positive active substances) to obtain a battery core, sealing the battery core by a film, packaging a battery shell of the battery core, welding a shell opening, vacuum drying, injecting electrolyte into the battery shell, packaging, standing, forming and separating to obtain the lithium ion battery.
The measurement items comprise compaction density and capacity retention rate of the lithium ion battery after 1 circle, 20 circles, 100 circles, 500 circles and 1000 circles of cyclic charge and discharge, and the surface appearance of the membrane after 1000 circles of cyclic charge and discharge is observed by an electron microscope.
Table 1 examples 1 to 8 and comparative examples 1 to 4 were measured for item data
Under the condition that the thicknesses and the compaction densities of the films of examples 1-8 and comparative examples 1-4 are similar, the 1 st, 20 th, 100 th, 500 th and 1000 th turn capacity retention rates of the lithium ion battery prepared by the method are obviously better than those of the 1 st, 20 th, 100 th, 500 th and 1000 th turn capacity retention rates of comparative examples 1-4, the appearance of the film of the lithium ion battery of examples 1-8 is also better than that of the film of the lithium ion battery of comparative examples 1-4, and the fact that the film of examples 1-8 has higher dynamic properties of lithium removal and lithium intercalation is shown, so that the lithium ion battery has higher first coulombic efficiency and better capacity retention rate.
Variations and modifications of the above embodiments will occur to those skilled in the art to which the invention pertains from the foregoing disclosure and teachings. Therefore, the present invention is not limited to the above-described embodiments, but is intended to be capable of modification, substitution or variation in light thereof, which will be apparent to those skilled in the art in light of the present teachings. In addition, although specific terms are used in the present specification, these terms are for convenience of description only and do not limit the present invention in any way.
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Country or region after: China Address after: 215500 No. 68, Xin'anjiang Road, Southeast street, Changshu, Suzhou, Jiangsu Applicant after: Jiangsu Zhengli New Energy Battery Technology Co.,Ltd. Address before: 215500 No. 68, Xin'anjiang Road, Southeast street, Changshu, Suzhou, Jiangsu Applicant before: Jiangsu Zenergy Battery Technologies Co.,ltd Country or region before: China |
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