CN114497451B - Negative plate and preparation method and application thereof - Google Patents
Negative plate and preparation method and application thereof Download PDFInfo
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- CN114497451B CN114497451B CN202210104227.5A CN202210104227A CN114497451B CN 114497451 B CN114497451 B CN 114497451B CN 202210104227 A CN202210104227 A CN 202210104227A CN 114497451 B CN114497451 B CN 114497451B
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- 238000002360 preparation method Methods 0.000 title abstract description 19
- 239000003575 carbonaceous material Substances 0.000 claims abstract description 52
- 239000006183 anode active material Substances 0.000 claims abstract description 50
- 239000007773 negative electrode material Substances 0.000 claims abstract description 46
- 125000005842 heteroatom Chemical group 0.000 claims abstract description 45
- 239000011230 binding agent Substances 0.000 claims abstract description 40
- 229910021385 hard carbon Inorganic materials 0.000 claims abstract description 23
- 239000006258 conductive agent Substances 0.000 claims abstract description 19
- 229910052698 phosphorus Inorganic materials 0.000 claims abstract description 18
- 239000011159 matrix material Substances 0.000 claims abstract description 15
- 229910052796 boron Inorganic materials 0.000 claims abstract description 14
- 229910052717 sulfur Inorganic materials 0.000 claims abstract description 14
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 12
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 11
- 239000010703 silicon Substances 0.000 claims abstract description 11
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 4
- 239000010410 layer Substances 0.000 claims description 77
- 239000000463 material Substances 0.000 claims description 74
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 52
- 238000010438 heat treatment Methods 0.000 claims description 38
- 239000002245 particle Substances 0.000 claims description 31
- 229910052799 carbon Inorganic materials 0.000 claims description 28
- OBNDGIHQAIXEAO-UHFFFAOYSA-N [O].[Si] Chemical compound [O].[Si] OBNDGIHQAIXEAO-UHFFFAOYSA-N 0.000 claims description 27
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 24
- 239000000126 substance Substances 0.000 claims description 21
- 239000002243 precursor Substances 0.000 claims description 20
- 238000001035 drying Methods 0.000 claims description 18
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 claims description 17
- 239000000758 substrate Substances 0.000 claims description 17
- 239000011248 coating agent Substances 0.000 claims description 16
- 238000000576 coating method Methods 0.000 claims description 16
- 238000000034 method Methods 0.000 claims description 15
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims description 14
- 239000002131 composite material Substances 0.000 claims description 14
- 239000011267 electrode slurry Substances 0.000 claims description 14
- 239000011574 phosphorus Substances 0.000 claims description 14
- 239000002904 solvent Substances 0.000 claims description 12
- 238000004321 preservation Methods 0.000 claims description 11
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 claims description 10
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims description 10
- 229910021389 graphene Inorganic materials 0.000 claims description 10
- 229910002804 graphite Inorganic materials 0.000 claims description 10
- 239000010439 graphite Substances 0.000 claims description 10
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 10
- 239000000377 silicon dioxide Substances 0.000 claims description 10
- 239000011593 sulfur Substances 0.000 claims description 10
- 238000007740 vapor deposition Methods 0.000 claims description 10
- 239000007789 gas Substances 0.000 claims description 8
- 230000001681 protective effect Effects 0.000 claims description 8
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 8
- DPXJVFZANSGRMM-UHFFFAOYSA-N acetic acid;2,3,4,5,6-pentahydroxyhexanal;sodium Chemical compound [Na].CC(O)=O.OCC(O)C(O)C(O)C(O)C=O DPXJVFZANSGRMM-UHFFFAOYSA-N 0.000 claims description 7
- 239000001768 carboxy methyl cellulose Substances 0.000 claims description 7
- 238000000151 deposition Methods 0.000 claims description 7
- 239000000203 mixture Substances 0.000 claims description 7
- 235000019812 sodium carboxymethyl cellulose Nutrition 0.000 claims description 7
- 229920001027 sodium carboxymethylcellulose Polymers 0.000 claims description 7
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims description 6
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 claims description 6
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 6
- 229920002125 Sokalan® Polymers 0.000 claims description 5
- 229920000877 Melamine resin Polymers 0.000 claims description 4
- HSFWRNGVRCDJHI-UHFFFAOYSA-N alpha-acetylene Natural products C#C HSFWRNGVRCDJHI-UHFFFAOYSA-N 0.000 claims description 4
- MNNHAPBLZZVQHP-UHFFFAOYSA-N diammonium hydrogen phosphate Chemical compound [NH4+].[NH4+].OP([O-])([O-])=O MNNHAPBLZZVQHP-UHFFFAOYSA-N 0.000 claims description 4
- 229910000388 diammonium phosphate Inorganic materials 0.000 claims description 4
- 235000019838 diammonium phosphate Nutrition 0.000 claims description 4
- 125000002534 ethynyl group Chemical group [H]C#C* 0.000 claims description 4
- JDSHMPZPIAZGSV-UHFFFAOYSA-N melamine Chemical compound NC1=NC(N)=NC(N)=N1 JDSHMPZPIAZGSV-UHFFFAOYSA-N 0.000 claims description 4
- 239000004584 polyacrylic acid Substances 0.000 claims description 4
- LIVNPJMFVYWSIS-UHFFFAOYSA-N silicon monoxide Chemical compound [Si-]#[O+] LIVNPJMFVYWSIS-UHFFFAOYSA-N 0.000 claims description 4
- 229910052814 silicon oxide Inorganic materials 0.000 claims description 4
- 229920003048 styrene butadiene rubber Polymers 0.000 claims description 4
- IXPNQXFRVYWDDI-UHFFFAOYSA-N 1-methyl-2,4-dioxo-1,3-diazinane-5-carboximidamide Chemical compound CN1CC(C(N)=N)C(=O)NC1=O IXPNQXFRVYWDDI-UHFFFAOYSA-N 0.000 claims description 3
- 229920000049 Carbon (fiber) Polymers 0.000 claims description 3
- 229920001661 Chitosan Polymers 0.000 claims description 3
- 239000005696 Diammonium phosphate Substances 0.000 claims description 3
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 claims description 3
- 239000005977 Ethylene Substances 0.000 claims description 3
- 239000004372 Polyvinyl alcohol Substances 0.000 claims description 3
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 claims description 3
- HMDDXIMCDZRSNE-UHFFFAOYSA-N [C].[Si] Chemical compound [C].[Si] HMDDXIMCDZRSNE-UHFFFAOYSA-N 0.000 claims description 3
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims description 3
- 239000006256 anode slurry Substances 0.000 claims description 3
- 239000007864 aqueous solution Substances 0.000 claims description 3
- KGBXLFKZBHKPEV-UHFFFAOYSA-N boric acid Chemical compound OB(O)O KGBXLFKZBHKPEV-UHFFFAOYSA-N 0.000 claims description 3
- 239000004327 boric acid Substances 0.000 claims description 3
- 229910052810 boron oxide Inorganic materials 0.000 claims description 3
- 239000004202 carbamide Substances 0.000 claims description 3
- 239000004917 carbon fiber Substances 0.000 claims description 3
- 229910021393 carbon nanotube Inorganic materials 0.000 claims description 3
- 239000002041 carbon nanotube Substances 0.000 claims description 3
- 125000002057 carboxymethyl group Chemical group [H]OC(=O)C([H])([H])[*] 0.000 claims description 3
- 239000011247 coating layer Substances 0.000 claims description 3
- JKWMSGQKBLHBQQ-UHFFFAOYSA-N diboron trioxide Chemical compound O=BOB=O JKWMSGQKBLHBQQ-UHFFFAOYSA-N 0.000 claims description 3
- BNIILDVGGAEEIG-UHFFFAOYSA-L disodium hydrogen phosphate Chemical compound [Na+].[Na+].OP([O-])([O-])=O BNIILDVGGAEEIG-UHFFFAOYSA-L 0.000 claims description 3
- 229910000397 disodium phosphate Inorganic materials 0.000 claims description 3
- 235000019800 disodium phosphate Nutrition 0.000 claims description 3
- 239000001866 hydroxypropyl methyl cellulose Substances 0.000 claims description 3
- 235000010979 hydroxypropyl methyl cellulose Nutrition 0.000 claims description 3
- 229920003088 hydroxypropyl methyl cellulose Polymers 0.000 claims description 3
- UFVKGYZPFZQRLF-UHFFFAOYSA-N hydroxypropyl methyl cellulose Chemical compound OC1C(O)C(OC)OC(CO)C1OC1C(O)C(O)C(OC2C(C(O)C(OC3C(C(O)C(O)C(CO)O3)O)C(CO)O2)O)C(CO)O1 UFVKGYZPFZQRLF-UHFFFAOYSA-N 0.000 claims description 3
- 235000011007 phosphoric acid Nutrition 0.000 claims description 3
- 229920002239 polyacrylonitrile Polymers 0.000 claims description 3
- 229920002451 polyvinyl alcohol Polymers 0.000 claims description 3
- 239000001294 propane Substances 0.000 claims description 3
- 239000002002 slurry Substances 0.000 claims description 3
- 239000000661 sodium alginate Substances 0.000 claims description 3
- 235000010413 sodium alginate Nutrition 0.000 claims description 3
- 229940005550 sodium alginate Drugs 0.000 claims description 3
- 239000001488 sodium phosphate Substances 0.000 claims description 3
- YUKQRDCYNOVPGJ-UHFFFAOYSA-N thioacetamide Chemical compound CC(N)=S YUKQRDCYNOVPGJ-UHFFFAOYSA-N 0.000 claims description 3
- DLFVBJFMPXGRIB-UHFFFAOYSA-N thioacetamide Natural products CC(N)=O DLFVBJFMPXGRIB-UHFFFAOYSA-N 0.000 claims description 3
- 238000004519 manufacturing process Methods 0.000 claims 10
- 229910052760 oxygen Inorganic materials 0.000 abstract description 6
- 125000004429 atom Chemical group 0.000 abstract description 3
- 241000894007 species Species 0.000 description 24
- 239000011149 active material Substances 0.000 description 10
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 9
- 229910001416 lithium ion Inorganic materials 0.000 description 9
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 8
- 230000000052 comparative effect Effects 0.000 description 8
- 229910052744 lithium Inorganic materials 0.000 description 8
- 230000014759 maintenance of location Effects 0.000 description 6
- 239000000853 adhesive Substances 0.000 description 5
- 230000001070 adhesive effect Effects 0.000 description 5
- 230000007547 defect Effects 0.000 description 5
- 238000001179 sorption measurement Methods 0.000 description 5
- 239000013543 active substance Substances 0.000 description 4
- 238000009826 distribution Methods 0.000 description 4
- 239000003792 electrolyte Substances 0.000 description 4
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 3
- 239000010405 anode material Substances 0.000 description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 239000011889 copper foil Substances 0.000 description 3
- 230000008021 deposition Effects 0.000 description 3
- 230000005012 migration Effects 0.000 description 3
- 238000013508 migration Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 230000010287 polarization Effects 0.000 description 3
- 239000002210 silicon-based material Substances 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- 238000007605 air drying Methods 0.000 description 2
- 229910021383 artificial graphite Inorganic materials 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000009831 deintercalation Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000011534 incubation Methods 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 208000019901 Anxiety disease Diseases 0.000 description 1
- 241001391944 Commicarpus scandens Species 0.000 description 1
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 1
- 239000002033 PVDF binder Substances 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000003044 adaptive effect Effects 0.000 description 1
- 230000036506 anxiety Effects 0.000 description 1
- 239000012298 atmosphere Substances 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 239000002134 carbon nanofiber Substances 0.000 description 1
- 239000006182 cathode active material Substances 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 238000007323 disproportionation reaction Methods 0.000 description 1
- 125000000524 functional group Chemical group 0.000 description 1
- 239000007770 graphite material Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 239000005543 nano-size silicon particle Substances 0.000 description 1
- 229910021382 natural graphite Inorganic materials 0.000 description 1
- 125000004433 nitrogen atom Chemical group N* 0.000 description 1
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000006479 redox reaction Methods 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 150000003376 silicon Chemical class 0.000 description 1
- 239000011866 silicon-based anode active material Substances 0.000 description 1
- 239000002356 single layer Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 230000001502 supplementing effect Effects 0.000 description 1
- 230000003746 surface roughness Effects 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
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
-
- 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
- H01M10/04—Construction or manufacture in general
-
- 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
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/362—Composites
- H01M4/366—Composites as layered products
-
- 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
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
- H01M4/386—Silicon or alloys based on silicon
-
- 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
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Composite Materials (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The invention relates to the technical field of batteries, in particular to a negative plate and a preparation method and application thereof. A negative electrode sheet including a negative electrode current collector, a first negative electrode active layer, and a second negative electrode active layer; the negative electrode current collector comprises a negative electrode current collector matrix and a carbon material layer arranged on at least one side surface of the negative electrode current collector matrix, wherein a first negative electrode active layer is arranged on the surface of the carbon material layer, which is far away from the negative electrode current collector matrix, and a second negative electrode active layer is arranged on the surface of the first negative electrode active layer, which is far away from the negative electrode current collector; the first negative electrode active layer comprises a first negative electrode active material, a first binder and a first conductive agent, wherein the first negative electrode active material comprises a silicon-based negative electrode material doped with hetero atoms; the second anode active layer includes a second anode active material including a hard carbon material doped with hetero atoms and a second binder; the atoms include at least one of P, N, S, B and O. The negative electrode sheet has excellent quick charge performance.
Description
Technical Field
The invention relates to the technical field of batteries, in particular to a negative plate and a preparation method and application thereof.
Background
In recent years, sales of new energy automobiles are gradually increased, and performance of lithium ion batteries as power sources is also required to be higher and higher in various aspects, wherein in order to solve the problem of 'cruising and charging anxiety' of products, the new lithium ion batteries are required to have higher energy density and faster charging time. Graphite is used as a cathode active material which is most mature in the current industry, the practical playing capacity of the graphite is basically close to the theoretical capacity, and the high energy density index is difficult to meet. Based on the existing positive electrode main material and battery formula system, the graphite mixed silicon-based negative electrode is beneficial to further improving the energy density of the lithium ion battery, and the disadvantage of short endurance mileage of the new energy automobile can be effectively solved. However, the inherent semiconductor property of the silicon material limits the quick charge capacity of the battery, and the difference of the electron migration efficiencies of the two materials in the charge and discharge processes can cause uneven current distribution in the negative plate, so that the potential of a local area is easy to break through the lower limit of 0V, lithium deposition is generated, the quick charge performance of the power battery is reduced, and the safety is influenced.
The silica-doped ink negative electrode plate is easy to generate uneven distribution of conductive carbon and unstable binder network in mixed homogenate coating due to different surface tension of particles of two materials and different adsorption capacities of the conductive carbon and the binder, so that the battery multiplying power performance is not ideal; because the electrochemical deintercalation lithium potential of the graphite material is different from that of the silicon material, the problem of deintercalation lithium of two different active material materials can occur, the current distribution in the negative electrode plate is quite uneven, and local metal lithium deposition is easy to occur, so that the safety of the battery is influenced; therefore, how to obtain a pole piece with high-rate characteristics by using two different active materials as main materials is a technical problem to be solved.
In view of this, the present invention has been made.
Disclosure of Invention
An object of the present invention is to provide a negative electrode sheet, which can improve the fast charge performance of the sheet by providing a specific negative electrode current collector, a first negative electrode active layer, and a second negative electrode active layer in cooperation.
The invention also aims to provide a preparation method of the negative plate, which is simple and easy to implement.
Another object of the present invention is to provide a battery having excellent cycle performance and rate performance.
In order to achieve the above object of the present invention, the following technical solutions are specifically adopted:
a negative electrode sheet including a negative electrode current collector, a first negative electrode active layer, and a second negative electrode active layer; the negative electrode current collector comprises a negative electrode current collector matrix and a carbon material layer arranged on at least one side surface of the negative electrode current collector matrix, wherein the surface of the carbon material layer, which is far away from the negative electrode current collector matrix, is provided with a first negative electrode active layer, and the surface of the first negative electrode active layer, which is far away from the negative electrode current collector, is provided with a second negative electrode active layer;
the first negative electrode active layer comprises a first negative electrode active material, a first binder and a first conductive agent, wherein the first negative electrode active material comprises a silicon-based negative electrode material doped with a first hetero atom;
the second anode active layer comprises a second anode active material and a second binder, the second anode active material comprises a hard carbon material, and a second hetero atom is doped in the hard carbon material;
the first heteroatom and the second heteroatom include at least one of P, N, S, B and O, respectively.
Preferably, the silicon-based anode material comprises a silicon-oxygen composite material and a carbon coating layer coated on at least part of the surface of the silicon-oxygen composite material, wherein the silicon-oxygen composite material comprises Si and SiO x Wherein x is more than or equal to 0.8 and less than or equal to 1.2;
preferably, in the first anode active material, the doping amount of the first hetero atom is 3at% to 8at%;
preferably, in the second anode active material, the doping amount of the second hetero atom is 2at% to 5at%;
preferably, the mass ratio of the first anode active material to the second anode active material is (5% -30%): (70% -95%).
Preferably, the silicon-based anode material comprises at least one of a nano silicon-carbon material, a silicon oxygen material and a lithium supplementing silicon oxygen material;
preferably, the first negative electrode active material has a particle diameter D50 of 1 to 20 μm, preferably 3 to 10 μm;
preferably, the ratio of the particle diameter D90 and the particle diameter D50 of the first anode active material is (1.7 to 3.5): 1, a step of;
preferably, the mass ratio of the first anode active material, the first binder and the first conductive agent is (95% -98%): (1% -3%): (1% -2%);
preferably, the first binder comprises at least one of sodium carboxymethyl cellulose, polyacrylic acid, sodium alginate, carboxymethyl chitosan, polyacrylonitrile and polyvinyl alcohol;
preferably, the first conductive agent includes at least one of conductive graphite, conductive carbon black, carbon nanotubes, carbon fibers, and graphene.
Preferably, the particle diameter D50 of the second anode active material is 10 to 25 μm, preferably 15 to 20 μm;
preferably, the ratio of the particle diameter D50 of the second anode active material to the particle diameter D50 of the first anode active material is (1.5-6): 1;
preferably, the mass ratio of the second anode active material to the second binder is (95% -98%): (2% -5%);
preferably, the second binder includes at least one of styrene-butadiene rubber, sodium carboxymethyl cellulose, and hydroxypropyl methyl cellulose.
Preferably, the roughness of the negative electrode current collector is more than or equal to 0.1 mu m;
preferably, the carbon material layer includes at least one of graphite and graphene;
preferably, the thickness of the first anode active layer is 20 to 60 μm;
preferably, the thickness of the second anode active layer is 120 to 160 μm;
preferably, the thickness of the carbon material layer is 2 to 5 μm.
The preparation method of the negative plate comprises the following steps:
coating carbon material slurry on at least one side surface of the negative electrode current collector matrix, and drying to obtain a negative electrode current collector with a carbon material layer; coating a first negative electrode slurry on the surface of the carbon material layer far away from the negative electrode current collector substrate, and drying to obtain a first negative electrode active layer; coating a second negative electrode slurry on the surface of the first negative electrode active layer, which is far away from the negative electrode current collector substrate, and drying to obtain a second negative electrode active layer;
the first negative electrode slurry includes the first negative electrode active material, a first binder, a first conductive agent, and a first solvent;
the second anode slurry includes the second anode active material, a second binder, and a second solvent.
The first solvent and the second solvent of the present invention each include N-methylpyrrolidone.
Preferably, the preparation method of the first negative active material includes the steps of:
performing first heat treatment on a silicon-oxygen material under the condition of protective gas to obtain a silicon-oxygen composite substrate, and depositing a carbon source on the surface of the silicon-oxygen composite substrate in a vapor deposition mode to form a carbon-coated silicon-oxygen material; drying the mixture of the carbon-coated silica material, the precursor material of the first hetero atom and water, and performing a second heat treatment on the dried material under the condition of protective gas;
preferably, the precursor material of the first heteroatom includes at least one of a nitrogen-containing species, a phosphorus-containing species, a sulfur-containing species, and a boron-containing species;
preferably, the nitrogen-containing substance comprises at least one of melamine and urea;
preferably, the phosphorus-containing material includes at least one of diammonium phosphate, disodium phosphate, and phosphoric acid;
preferably, the sulfur-containing material comprises sulfuric acid, na 2 At least one of an aqueous solution of S and thioacetamide;
preferably, the boron-containing material comprises at least one of boric acid and boron oxide;
preferably, the mass ratio of the carbon-coated silica material to the nitrogen-containing substance is 1: (2-4);
preferably, the carbon source comprises at least one of methane, acetylene, propane and ethylene;
preferably, the temperature of the first heat treatment is 350-450 ℃, and the heat preservation time of the first heat treatment is 55-65 min;
preferably, the temperature of the vapor deposition is 600-1000 ℃ and the time is 25-40 min;
preferably, the temperature of the second heat treatment is 550-750 ℃, and the heat preservation time of the second heat treatment is 90-150 min.
Preferably, the preparation method of the second anode active material includes the following steps:
and drying the mixture of the hard carbon material, the precursor material of the second hetero atom and water, and performing third heat treatment on the dried material.
Preferably, the precursor material of the second heteroatom comprises at least one of a nitrogen-containing species, a phosphorus-containing species, a sulfur-containing species, and a boron-containing species;
preferably, the mass ratio of the hard carbon material to the precursor material of the second heteroatom is 1: (4-10);
preferably, the temperature of the third heat treatment is 60-90 ℃, and the heat preservation time of the third heat treatment is 60-120 min.
A battery comprises the negative plate.
Compared with the prior art, the invention has the beneficial effects that:
(1) According to the invention, by doping different atoms on the two anode active materials, the diffusion coefficients of lithium ions in the two materials are more approximate, so that the local metal lithium deposition phenomenon formed by uneven current distribution in the pole piece is inhibited to a certain extent, and the quick charge characteristic of the pole piece is improved; compared with the traditional current collector, the compatibility between the current collector after the prime coating and the second layer of negative electrode active material is better, the migration efficiency of electrons at the interface is promoted, the polarization is reduced, and the pole piece quick charge characteristic is improved.
(2) The negative electrode plate adopts a multi-layer structure, the silicon-based material and the hard carbon material are respectively used as the active material layers, so that the common competition of conductive carbon adsorption is avoided, the conductive carbon adsorption and the hard carbon adsorption are cooperated with each other to play a role, and the overall electrical performance of the battery is improved.
(3) The preparation method of the negative plate is simple and easy to implement.
(4) The battery of the invention has excellent cycle performance and rate performance.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the description of the embodiments or the prior art will be briefly described, and it is obvious that the drawings in the description below are some embodiments of the present invention, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic structural diagram of a negative plate in embodiment 1 of the present invention;
fig. 2 is a graph of capacity retention ratio of the battery;
fig. 3 is a graph showing comparison of rate charging performance of the battery.
Detailed Description
Embodiments of the present invention will be described in detail below with reference to examples, but it will be understood by those skilled in the art that the following examples are only for illustrating the present invention and should not be construed as limiting the scope of the present invention. The specific conditions are not noted in the examples and are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.
According to one aspect of the present invention, the present invention relates to a negative electrode sheet including a negative electrode current collector, a first negative electrode active layer, and a second negative electrode active layer; the negative electrode current collector comprises a negative electrode current collector matrix and a carbon material layer arranged on at least one side surface of the negative electrode current collector matrix, wherein the surface of the carbon material layer, which is far away from the negative electrode current collector matrix, is provided with a first negative electrode active layer, and the surface of the first negative electrode active layer, which is far away from the negative electrode current collector, is provided with a second negative electrode active layer;
the first negative electrode active layer comprises a first negative electrode active material, a first binder and a first conductive agent, wherein the first negative electrode active material comprises a silicon-based negative electrode material doped with a first hetero atom;
the second anode active layer comprises a second anode active material and a second binder, the second anode active material comprises a hard carbon material, and a second hetero atom is doped in the hard carbon material;
the first heteroatom and the second heteroatom include at least one of P, N, S, B and O, respectively.
In the invention, the two active materials can form a disordered structure defect on the surface by introducing hetero atoms, and the defects obviously improve the wettability with the surface of electrolyte and enhance the conductivity; at the same time promote Li + Absorption, diffusion and transport, reduced active material to active material, active material to current collectorInterfacial polarization between.
In one embodiment, a carbon material layer, a first anode active layer, and a second anode active layer are sequentially stacked on one surface of an anode current collector substrate.
In one embodiment, a carbon material layer, a first anode active layer, and a second anode active layer are sequentially stacked on both side surfaces of an anode current collector substrate, respectively.
In one embodiment, the roughness of the negative electrode current collector is equal to or greater than 0.1 μm. For example, 0.15 μm, 0.2 μm, 0.25 μm, 0.3 μm, 0.35 μm, 0.4 μm, etc. are possible. For example, the particle size may be 0.1 to 0.5. Mu.m.
In one embodiment, the carbon material layer includes at least one of graphite and graphene.
In one embodiment, the negative current collector substrate comprises copper foil. The bottom-coating copper foil is used, so that the adhesive force between the anode active material layer and the current collector can be obviously improved, and the quick-charging use stability of the pole piece is enhanced; the carbon material adopted in one embodiment of the invention is a graphene material, and compared with the traditional current collector, the graphene coating has more contact sites, can be used for attaching a second layer of negative electrode active substances, and improves the cohesive force of the pole piece; in addition, the graphene material can improve the compatibility between the second-layer anode active material and the current collector, promote the migration efficiency of electrons at the interface, reduce polarization and further improve the pole piece fast charge characteristic.
The thickness of the first anode active layer and the thickness of the second anode active layer can be adjusted according to actual requirements.
In one embodiment, the first negative electrode active layer has a thickness of 20 to 60 μm.
In one embodiment, the second anode active layer has a thickness of 120 to 160 μm.
In one embodiment, the carbon material layer has a thickness of 2 to 5 μm.
In one embodiment, the silicon-based anode material comprises a silicon oxide material and a carbon coating layer coated on at least part of the surface of the silicon oxide material, wherein the silicon oxide material comprisesSi and SiO x Wherein x is more than or equal to 0.8 and less than or equal to 1.2.
In one embodiment, the first negative electrode active material has a doping amount of the first hetero atom of 3at% to 8at%. For example, 3at%, 3.2at%, 3.5at%, 3.7at%, 4at%, 4.5at%, 5at%, 6at%, 7at% may be included.
In one embodiment, the second negative electrode active material has a doping amount of the second hetero atom of 2at% to 5at%. In one embodiment, the doping amount of the second heteroatom includes, but is not limited to, 2.2at%, 2.5at%, 2.7at%, 3at%, 3.2at%, 3.5at%, 3.7at%, 4at%, 4.2at%, 4.5at%, 4.7at%, or 5at%. The conductivity of the negative plate is improved better by regulating and controlling the doping amount of the hetero atoms, the wettability of the negative plate and the electrolyte surface is improved, and the cycle performance of the battery is improved. When the doping amount of the hetero atoms is low, defects in the hard carbon material are few, the binding force of chemical bonds is insufficient, the number of generated lithium ion active sites is also insufficient, and the improvement effect on the lithium storage capacity is limited; when the doping amount of the hetero atoms is too high, defects in the hard carbon material are formed much, so that the shuttle resistance of lithium ions in the material is larger, and the overall rate performance of the material is affected;
in one embodiment, the mass ratio of the first anode active material to the second anode active material is (5% -30%): (70% -95%). In one embodiment, the mass ratio of the first anode active material to the second anode active material includes, but is not limited to, 5%:95%, 10%:90%, 12%:88%, 15%:85%, 20%:80%, 25%:75%, 30%:70%.
In one embodiment, the silicon-based negative electrode material includes at least one of a nano silicon carbon material, a silicon oxygen material, and a lithium-supplementing silicon oxygen material.
In one embodiment, the first negative electrode active material has a particle diameter D50 of 1 to 20 μm, preferably 3 to 10 μm. In one embodiment, the particle diameter D50 of the first anode active material includes, but is not limited to, 2 μm, 3 μm, 5 μm, 6 μm, 8 μm, 10 μm, 12 μm, 15 μm, 16 μm, 18 μm, or 19 μm.
In one embodiment, the ratio of the particle diameter D90 and the particle diameter D50 of the first anode active material is (1.7 to 3.5): 1. in one embodiment, the ratio of the particle diameter D90 and the particle diameter D50 of the first anode active material includes, but is not limited to, 1.8: 1. 2: 1. 2.2: 1. 2.5:1, 2.7:1, 3:1, or 3.5:1.
In one embodiment, the mass ratio of the first anode active material, the first binder, and the first conductive agent is (95% -98%): (1% -3%): (1% -2%). In one embodiment, the mass ratio of the first anode active material, the first binder, and the first conductive agent includes, but is not limited to, 95%:2%:2%, 96%:3%:1% or 97%:2%:1%. The electrical property and the mechanical property of the negative plate can be further improved better by adopting a proper dosage ratio.
In one embodiment, the first binder includes at least one of sodium carboxymethyl cellulose, polyacrylic acid, sodium alginate, carboxymethyl chitosan, polyacrylonitrile, and polyvinyl alcohol.
In one embodiment, the first conductive agent includes at least one of conductive graphite, conductive carbon black, carbon nanotubes, carbon fibers (VGCF), and graphene.
In one embodiment, the particle diameter D50 of the second anode active material is 10 to 25 μm, preferably 15 to 20 μm. In one embodiment, the particle size D50 of the second anode active material includes, but is not limited to, 12 μm, 15 μm, 17 μm, 19 μm, 20 μm, 22 μm, or 25 μm.
In one embodiment, the ratio of the particle diameter D50 of the second anode active material to the particle diameter D50 of the first anode active material is (1.5-6): 1. In an embodiment, the ratio of the particle size D50 of the second anode active material to the particle size D50 of the first anode active material includes, but is not limited to, 2.2:1, 2.5:1, 2.7:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, or 5.5:1.
In one embodiment, the mass ratio of the second anode active material to the second binder is (95% -98%): (2% -5%). In one embodiment, the mass ratio of the second anode active material to the second binder includes, but is not limited to, 95%:5%, 96%:4%, 97%:3% or 98%:2%.
In one embodiment, the second binder includes at least one of styrene-butadiene rubber, sodium carboxymethyl cellulose, and hydroxypropyl methyl cellulose.
The invention uses the adhesive which is respectively matched with different active materials, thereby avoiding the damage of the multidimensional structure of the adhesive, reducing the adhesive force of the pole piece and affecting the stability of the pole piece.
According to another aspect of the invention, the invention relates to a preparation method of the negative plate, comprising the following steps:
coating carbon material slurry on at least one side surface of the negative electrode current collector matrix, and drying to obtain a negative electrode current collector with a carbon material layer; coating a first negative electrode slurry on the surface of the carbon material layer far away from the negative electrode current collector substrate, and drying to obtain a first negative electrode active layer; coating a second negative electrode slurry on the surface of the first negative electrode active layer, which is far away from the negative electrode current collector substrate, and drying to obtain a second negative electrode active layer;
the first negative electrode slurry includes the first negative electrode active material, a first binder, a first conductive agent, and a first solvent;
the second anode slurry includes the second anode active material, a second binder, and a second solvent.
The preparation method of the invention is simple and easy to implement.
In one embodiment, the method for preparing the first negative active material includes the steps of:
performing first heat treatment on a silicon-oxygen material under the condition of protective gas to obtain a silicon-oxygen composite substrate, and depositing a carbon source on the surface of the silicon-oxygen composite substrate in a vapor deposition mode to form a carbon-coated silicon-oxygen material; and drying the mixture of the carbon-coated silica material, the precursor material of the first hetero atom and water, and performing second heat treatment on the dried material under the condition of protective gas.
In one embodiment, the precursor material of the first heteroatom includes at least one of a nitrogen-containing species, a phosphorus-containing species, a sulfur-containing species, a boron-containing species, and an oxygen-containing species.
In one embodiment, the precursor material of the first heteroatom includes at least one of a nitrogen-containing species, a phosphorus-containing species, a sulfur-containing species, and a boron-containing species. In one embodiment, the nitrogen-containing substance includes at least one of melamine and urea. In one embodiment, the phosphorus-containing material includes at least one of diammonium phosphate, disodium phosphate, and phosphoric acid. In one embodiment, the sulfur species include sulfuric acid, na 2 At least one of an aqueous solution of S and thioacetamide. In one embodiment, the boron-containing material includes at least one of boric acid and boron oxide. The oxygen element is oxygen defect generated by disproportionation reaction.
In one embodiment, the mass ratio of the carbon-coated silica material to the nitrogen-containing species is 1: (2-4). In an embodiment, the mass ratio of the carbon-coated silica material to the nitrogen-containing species includes, but is not limited to, 1:2.1, 1:2.5, 1:2.7, 1:3, 1:3.2, 1:3.5, or 1:3.7.
In one embodiment, the carbon source comprises at least one of methane, acetylene, propane, and ethylene.
In one embodiment, the temperature of the first heat treatment is 350-450 ℃, and the heat preservation time of the first heat treatment is 55-65 min. In one embodiment, the temperature of the first heat treatment includes, but is not limited to, 360 ℃, 370 ℃, 380 ℃, 390 ℃, 400 ℃, 410 ℃, 420 ℃, 430 ℃, 440 ℃, or 445 ℃. The time of incubation for the first heat treatment includes, but is not limited to, 57min, 59min, 60min, 62min, or 64min.
In one embodiment, the vapor deposition is performed at a temperature of 600 to 1000 ℃ for a time of 25 to 40 minutes. In one embodiment, the temperature of vapor deposition includes, but is not limited to, 650 ℃, 700 ℃, 750 ℃, 800 ℃, 850 ℃, 900 ℃, 950 ℃, or 980 ℃. The time of vapor deposition was 27min, 30min, 33min, 35min, 37min, or 39min.
In one embodiment, the temperature of the second heat treatment is 550 to 750 ℃, and the time for maintaining the temperature of the second heat treatment is 90 to 150 minutes. In one embodiment, the temperature of the second heat treatment includes, but is not limited to, 560 ℃, 570 ℃, 580 ℃, 600 ℃, 620 ℃, 650 ℃, 670 ℃, 700 ℃, or 720 ℃. The incubation time for the second heat treatment includes, but is not limited to, 100min, 110min, 120min, 130min, 140min, or 145min.
In one embodiment, the method for preparing the second anode active material includes the steps of:
and drying the mixture of the hard carbon material, the precursor material of the second hetero atom and water, and performing third heat treatment on the dried material.
In one embodiment, the precursor material of the second heteroatom includes at least one of a nitrogen-containing species, a phosphorus-containing species, a sulfur-containing species, and a boron-containing species. The precursor material of the second heteroatom is the same as the precursor material of the first atom.
In one embodiment, the mass ratio of the hard carbon material to the precursor material of the second heteroatom is 1: (4-10). In an embodiment, the mass ratio of the hard carbon material to the precursor material of the second heteroatom includes, but is not limited to, 1:4.5, 1:5, 1:5.5, 1:6, 1:7, 1:or 1:9. The hard carbon material and the precursor material of the second hetero atom adopt proper mass ratio, so that the content of the second hetero atom is regulated and controlled to improve the electrochemical performance of the negative plate.
In one embodiment, the temperature of the third heat treatment is 60-90 ℃, and the time for heat preservation of the third heat treatment is 60-120 min. In one embodiment, the temperature of the third heat treatment includes, but is not limited to, 65 ℃, 70 ℃, 75 ℃, 80 ℃, 85 ℃, 90 ℃, 100 ℃, 110 ℃, or 120 ℃.
In one embodiment, the hetero atom is P, and the hard carbon doped with P has higher capacity, better multiplying power performance, faster ion transmission rate and more stable cycle characteristic than conventional artificial graphite, natural graphite and intermediate phase graphite, and the advantages are mainly attributed to P-C bond and P-O bond formed after P doping, the P-O and P-C bond can improve the adsorption effect on lithium ions, and meanwhile, the P-C bondCan participate in oxidation-reduction reaction to generate Li x PC y The two functions cooperatively to increase the material capacity.
According to another aspect, the present invention relates to a battery including the negative electrode sheet.
The battery has excellent cycle performance, multiplying power performance and long service life.
The lithium ion battery can be prepared by combining the positive plate, the diaphragm, the electrolyte and the multilayer plate according to the conventional technical means by a person skilled in the art. Compared with a battery before modification, the lithium ion battery prepared according to the scheme disclosed by the application can still keep excellent capacity exertion under high multiplying power, and the lithium separation window is widened by 2C.
The present invention will be further explained below with reference to specific examples and comparative examples.
Fig. 1 is a schematic structural diagram of a negative electrode sheet in embodiment 1 of the present invention. Fig. 2 is a graph showing the capacity retention ratio of the battery. Fig. 3 is a graph showing comparison of rate charging performance of the battery.
Example 1
The preparation method of the negative plate comprises the following steps:
1. preparation of first and second negative electrode active materials
Performing first heat treatment on SiO under the condition of protective gas to obtain a silica composite substrate, and depositing a carbon source on the surface of the silica composite substrate in a vapor deposition mode to form a carbon-coated silica material; uniformly dispersing the silicon oxygen material coated with carbon and nitrogen-containing substance by water solvent method, and air drying 2 Performing a second heat treatment in the atmosphere to form an N-atom doped modified silicon-based anode active material; wherein the carbon source is acetylene; the temperature of the first heat treatment is 400 ℃, and the heat preservation time is 60min; the temperature of vapor deposition is 800 ℃ and the time is 30min; the nitrogen-containing substance is melamine; the temperature of the second heat treatment is 650 ℃, and the heat preservation time is 120min; the mass ratio of the carbon-coated silica material to the nitrogen-containing substance is 1:3, a step of;
a method of preparing a second anode active material, comprising: uniformly dispersing a hard carbon material and a phosphorus-containing substance by a water solvent method, and then carrying out third heat treatment under protective gas after air drying to form a phosphorus doped modified hard carbon anode active material; wherein the phosphorus-containing material comprises diammonium hydrogen phosphate, the third heat treatment temperature is 90 ℃, the heat preservation time is 90min, and the mass ratio of the hard carbon material to the phosphorus-containing material is 1:7, preparing a base material;
2. preparation of negative electrode sheet
(1) Preparing a negative electrode current collector: coating carbon materials on the surfaces of two sides of a copper foil, wherein the carbon materials are dispersed graphene, and drying to obtain a negative electrode current collector, wherein the surface roughness is 0.15 mu m;
(2) Coating the surface of the carbon material layer of the negative electrode current collector with the first negative electrode slurry, and drying to obtain a first negative electrode active layer; the preparation method of the first negative electrode slurry comprises the following steps: uniformly mixing the first negative electrode active material with a first binder, a first conductive agent and a first solvent to obtain a first negative electrode slurry; the first negative electrode active material had a particle diameter D50 of 4 μm and a particle diameter D90 of 8; the first binder is polyacrylic acid; the first conductive agent is conductive carbon black; the mass ratio of the first anode active material, the first binder and the first conductive agent is 96%:2%:2%;
(3) Coating a second negative electrode slurry on the surface of the first negative electrode active layer, and drying to obtain a second negative electrode active layer; a method of preparing a second negative electrode slurry comprising: uniformly mixing a second anode active material, a second binder and a solvent; the particle diameter D50 of the second anode active material was 12 μm; the second binder is a mixture of styrene-butadiene rubber and sodium carboxymethyl cellulose; the mass ratio of the second anode active material to the second binder is 97%:3%;
wherein the mass ratio of the first anode active material to the second anode active material is 16%:84%.
Example 2
The preparation method of the negative plate comprises the following steps of: 2, the other conditions were the same as in example 1.
Example 3
The preparation method of the negative plate comprises the following steps of: 4, the other conditions were the same as in example 1.
Example 4
The preparation method of the negative plate comprises the following steps of: outside 4; other conditions were the same as in example 1.
Example 5
The preparation method of the negative plate comprises the following steps of: outside 10; other conditions were the same as in example 1.
Comparative example 1
The negative electrode sheet is prepared by adopting a conventional graphite-doped silicon-oxygen negative electrode material, wherein the proportion is as follows: active material, conductive agent, binder=96:2:2, binder is PAA, wherein the active material consists of 16% of silicon oxygen material and 84% of artificial graphite, and the whole capacity is 500mAh/g.
Experimental example
The negative electrode sheets of examples 1 to 5 and comparative example 1 were respectively combined with a positive electrode sheet, a separator, and an electrolyte to prepare batteries; wherein, the positive electrode comprises an active substance and a conductive agent, the active substance comprises binder=97:1:2, the binder is PVDF, and the active substance is NCM811; the overall capacity of the negative electrode sheets in examples 1 to 5 was 500mAh/g. The obtained soft pack battery electrical properties were mainly tested for battery cycle life and battery capacity retention at high rate, as shown in table 1.
Table 1 performance comparison of pouch cells
As can be seen from table 1: the negative electrode peel force in the examples was 26% greater than in the comparative examples, which may indicate that the adhesion of the multi-layer negative electrode was stronger than that of the single-layer electrode sheet, probably due to two points, first: the compatibility between the modified current collector and the second layer of negative electrode active material is better; second,: the two layers of negative electrode active materials are all adhesive which is adaptive to the active main material, so that the bonding degree of the active main material and the surface functional groups of the active main material is more compact, and the conclusion can be verified according to the rebound data of the full charge plate of the battery BOL.
Fig. 2 shows that the 1C/1C cycle at 25 ℃ of example 1 and comparative example 1 shows that the battery obtained by using the multilayer negative electrode sheet of the present invention has higher cycle stability, a retention of 90% at a cut-off, and a cycle life of 500cls, which is more than 200cls in comparative example.
Fig. 3 is a graph of the rate charge performance of the battery including the pole pieces of example 1 and comparative example, wherein the comparative example battery capacity retention rate is significantly lower than the battery of example 1 after 2C current density, and the two battery retention rates at 4C are 87.40% and 40.77%, respectively, and the fast charge capability of the pole piece is greatly increased after modification.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention.
Claims (39)
1. The negative electrode sheet is characterized by comprising a negative electrode current collector, a first negative electrode active layer and a second negative electrode active layer; the negative electrode current collector comprises a negative electrode current collector matrix and a carbon material layer arranged on at least one side surface of the negative electrode current collector matrix, wherein the surface of the carbon material layer, which is far away from the negative electrode current collector matrix, is provided with a first negative electrode active layer, and the surface of the first negative electrode active layer, which is far away from the negative electrode current collector, is provided with a second negative electrode active layer;
the first negative electrode active layer comprises a first negative electrode active material, a first binder and a first conductive agent, wherein the first negative electrode active material comprises a silicon-based negative electrode material doped with a first hetero atom;
the second anode active layer comprises a second anode active material and a second binder, the second anode active material comprises a hard carbon material, and a second hetero atom is doped in the hard carbon material;
the first and second heteroatoms include at least one of P, N, S and B, respectively.
2. The negative electrode sheet according to claim 1, wherein the silicon-based negative electrode material comprises a silicon-oxygen composite material and a carbon coating layer coated on at least part of the surface of the silicon-oxygen composite material, the silicon-oxygen composite material comprising Si and SiO x Wherein x is more than or equal to 0.8 and less than or equal to 1.2.
3. The negative electrode sheet according to claim 1, wherein the doping amount of the first hetero atom in the first negative electrode active material is 3at% to 8at%.
4. The negative electrode sheet according to claim 1, wherein the doping amount of the second hetero atom in the second negative electrode active material is 2at% to 5at%.
5. The negative electrode sheet according to claim 1, wherein a mass ratio of the first negative electrode active material to the second negative electrode active material is (5% -30%): (70% -95%).
6. The negative electrode sheet of claim 1, wherein the silicon-based negative electrode material comprises at least one of a nano silicon-carbon material, a silicon oxygen material, and a lithium-supplemented silicon oxygen material.
7. The negative electrode sheet according to claim 1, wherein the first negative electrode active material has a particle diameter D50 of 1 to 20 μm.
8. The negative electrode sheet according to claim 7, wherein the first negative electrode active material has a particle diameter D50 of 3 to 10 μm.
9. The negative electrode sheet according to claim 7, wherein the ratio of the particle diameter D90 and the particle diameter D50 of the first negative electrode active material is (1.7 to 3.5): 1.
10. the negative electrode sheet according to claim 1, wherein the mass ratio of the first negative electrode active material, the first binder, and the first conductive agent is (95% -98%): (1% -3%): (1% -2%).
11. The negative electrode sheet of claim 10, wherein the first binder comprises at least one of sodium carboxymethyl cellulose, polyacrylic acid, sodium alginate, carboxymethyl chitosan, polyacrylonitrile, and polyvinyl alcohol.
12. The negative electrode sheet of claim 10, wherein the first conductive agent comprises at least one of conductive graphite, conductive carbon black, carbon nanotubes, carbon fibers, and graphene.
13. The negative electrode sheet according to claim 1, wherein the particle diameter D50 of the second negative electrode active material is 10 to 25 μm.
14. The negative electrode sheet according to claim 13, wherein the particle diameter D50 of the second negative electrode active material is 15 to 20 μm.
15. The negative electrode sheet according to claim 13, wherein the ratio of the particle diameter D50 of the second negative electrode active material to the particle diameter D50 of the first negative electrode active material is (1.5 to 6): 1.
16. The negative electrode sheet according to claim 13, wherein the mass ratio of the second negative electrode active material and the second binder is (95% -98%): (2% -5%).
17. The negative electrode sheet of claim 13, wherein the second binder comprises at least one of styrene-butadiene rubber, sodium carboxymethyl cellulose, and hydroxypropyl methyl cellulose.
18. The negative electrode sheet according to claim 1, wherein the roughness of the negative electrode current collector is not less than 0.1 μm.
19. The negative electrode sheet of claim 1, wherein the carbon material layer comprises at least one of graphite and graphene.
20. The negative electrode sheet according to claim 1, wherein the thickness of the first negative electrode active layer is 20 to 60 μm.
21. The negative electrode sheet according to claim 1, wherein the thickness of the second negative electrode active layer is 120 to 160 μm.
22. The negative electrode sheet according to claim 1, wherein the thickness of the carbon material layer is 2-5 μm.
23. The method for preparing a negative electrode sheet according to any one of claims 1 to 22, characterized by comprising the steps of:
coating carbon material slurry on at least one side surface of the negative electrode current collector matrix, and drying to obtain a negative electrode current collector with a carbon material layer; coating a first negative electrode slurry on the surface of the carbon material layer far away from the negative electrode current collector substrate, and drying to obtain a first negative electrode active layer; coating a second negative electrode slurry on the surface of the first negative electrode active layer, which is far away from the negative electrode current collector substrate, and drying to obtain a second negative electrode active layer;
the first negative electrode slurry includes the first negative electrode active material, a first binder, a first conductive agent, and a first solvent;
the second anode slurry includes the second anode active material, a second binder, and a second solvent.
24. The method for producing a negative electrode sheet according to claim 23, characterized in that the method for producing a first negative electrode active material comprises the steps of:
performing first heat treatment on a silicon-oxygen material under the condition of protective gas to obtain a silicon-oxygen composite substrate, and depositing a carbon source on the surface of the silicon-oxygen composite substrate in a vapor deposition mode to form a carbon-coated silicon-oxygen material; and drying the mixture of the carbon-coated silica material, the precursor material of the first hetero atom and water, and performing second heat treatment on the dried material under the condition of protective gas.
25. The method according to claim 24, wherein the precursor material of the first hetero atom includes at least one of a nitrogen-containing substance, a phosphorus-containing substance, a sulfur-containing substance, and a boron-containing substance.
26. The method for producing a negative electrode sheet according to claim 25, wherein the nitrogen-containing substance includes at least one of melamine and urea.
27. The method for producing a negative electrode sheet according to claim 25, wherein the phosphorus-containing substance includes at least one of diammonium phosphate, disodium phosphate, and phosphoric acid.
28. The method for producing a negative electrode sheet according to claim 25, wherein the sulfur-containing substance comprises sulfuric acid, na 2 At least one of an aqueous solution of S and thioacetamide.
29. The method for producing a negative electrode sheet according to claim 25, wherein the boron-containing substance includes at least one of boric acid and boron oxide.
30. The method for producing a negative electrode sheet according to claim 25, wherein a mass ratio of the carbon-coated silicon oxide material to the nitrogen-containing substance is 1: (2-4).
31. The method for producing a negative electrode sheet according to claim 24, wherein the carbon source includes at least one of methane, acetylene, propane, and ethylene.
32. The method for preparing a negative electrode sheet according to claim 24, wherein the temperature of the first heat treatment is 350-450 ℃, and the heat preservation time of the first heat treatment is 55-65 min.
33. The method for preparing a negative electrode sheet according to claim 24, wherein the vapor deposition temperature is 600-1000 ℃ and the time is 25-40 min.
34. The method for preparing a negative electrode sheet according to claim 24, wherein the temperature of the second heat treatment is 550-750 ℃, and the time of heat preservation of the second heat treatment is 90-150 min.
35. The method for producing a negative electrode sheet according to claim 23, characterized in that the method for producing a second negative electrode active material comprises the steps of:
and drying the mixture of the hard carbon material, the precursor material of the second hetero atom and water, and performing third heat treatment on the dried material.
36. The method according to claim 35, wherein the precursor material of the second hetero atom includes at least one of a nitrogen-containing substance, a phosphorus-containing substance, a sulfur-containing substance, and a boron-containing substance.
37. The method of claim 35, wherein the mass ratio of the hard carbon material to the precursor material of the second hetero atom is 1: (4-10).
38. The method for preparing a negative electrode sheet according to claim 35, wherein the temperature of the third heat treatment is 60-90 ℃, and the time of heat preservation of the third heat treatment is 60-120 min.
39. A battery comprising the negative electrode sheet according to any one of claims 1 to 22.
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| CN111900356A (en) * | 2020-08-13 | 2020-11-06 | 珠海冠宇电池股份有限公司 | Negative plate and lithium ion battery comprising same |
| CN112838197A (en) * | 2019-11-25 | 2021-05-25 | 华为技术有限公司 | Negative electrode material, preparation method thereof, battery and terminal |
| CN113471440A (en) * | 2021-07-09 | 2021-10-01 | 惠州亿纬锂能股份有限公司 | Silica material, preparation method and application thereof |
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| CN107195893A (en) * | 2017-07-01 | 2017-09-22 | 合肥国轩高科动力能源有限公司 | A kind of lithium ion battery boron-doping silicon base negative material |
| CN107946576A (en) * | 2017-11-21 | 2018-04-20 | 中航锂电（洛阳）有限公司 | A kind of high magnification graphite cathode material and preparation method thereof, lithium ion battery |
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| CN111540882A (en) * | 2020-06-04 | 2020-08-14 | 湖北亿纬动力有限公司 | Negative pole piece, preparation method and application thereof |
| CN111900356A (en) * | 2020-08-13 | 2020-11-06 | 珠海冠宇电池股份有限公司 | Negative plate and lithium ion battery comprising same |
| CN113471440A (en) * | 2021-07-09 | 2021-10-01 | 惠州亿纬锂能股份有限公司 | Silica material, preparation method and application thereof |
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