CN116805679A - High specific capacity silicon-carbon composite negative electrode material and preparation method of pole piece thereof - Google Patents
High specific capacity silicon-carbon composite negative electrode material and preparation method of pole piece thereof Download PDFInfo
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- CN116805679A CN116805679A CN202310957985.6A CN202310957985A CN116805679A CN 116805679 A CN116805679 A CN 116805679A CN 202310957985 A CN202310957985 A CN 202310957985A CN 116805679 A CN116805679 A CN 116805679A
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- 238000002360 preparation method Methods 0.000 title claims abstract description 10
- 239000011868 silicon-carbon composite negative electrode material Substances 0.000 title claims description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 54
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 49
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 48
- 239000010703 silicon Substances 0.000 claims abstract description 48
- 239000005543 nano-size silicon particle Substances 0.000 claims abstract description 43
- 229910002804 graphite Inorganic materials 0.000 claims abstract description 40
- 239000010439 graphite Substances 0.000 claims abstract description 40
- 239000011870 silicon-carbon composite anode material Substances 0.000 claims abstract description 21
- 239000011248 coating agent Substances 0.000 claims abstract description 13
- 238000000576 coating method Methods 0.000 claims abstract description 13
- 238000001291 vacuum drying Methods 0.000 claims abstract description 13
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 11
- 239000002153 silicon-carbon composite material Substances 0.000 claims abstract description 11
- 239000011230 binding agent Substances 0.000 claims abstract description 10
- 239000006258 conductive agent Substances 0.000 claims abstract description 10
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 claims abstract description 6
- 238000000034 method Methods 0.000 claims abstract description 6
- 239000000203 mixture Substances 0.000 claims abstract description 5
- 239000004480 active ingredient Substances 0.000 claims abstract description 3
- 239000011889 copper foil Substances 0.000 claims abstract description 3
- 238000003756 stirring Methods 0.000 claims description 17
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 16
- CYIDZMCFTVVTJO-UHFFFAOYSA-N pyromellitic acid Chemical compound OC(=O)C1=CC(C(O)=O)=C(C(O)=O)C=C1C(O)=O CYIDZMCFTVVTJO-UHFFFAOYSA-N 0.000 claims description 14
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 10
- 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 9
- 239000001768 carboxy methyl cellulose Substances 0.000 claims description 9
- 239000008367 deionised water Substances 0.000 claims description 9
- 229910021641 deionized water Inorganic materials 0.000 claims description 9
- 235000019812 sodium carboxymethyl cellulose Nutrition 0.000 claims description 9
- 229920001027 sodium carboxymethylcellulose Polymers 0.000 claims description 9
- 239000002245 particle Substances 0.000 claims description 6
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 claims description 5
- RLHGFJMGWQXPBW-UHFFFAOYSA-N 2-hydroxy-3-(1h-imidazol-5-ylmethyl)benzamide Chemical compound NC(=O)C1=CC=CC(CC=2NC=NC=2)=C1O RLHGFJMGWQXPBW-UHFFFAOYSA-N 0.000 claims description 4
- ZPAKUZKMGJJMAA-UHFFFAOYSA-N Cyclohexane-1,2,4,5-tetracarboxylic acid Chemical compound OC(=O)C1CC(C(O)=O)C(C(O)=O)CC1C(O)=O ZPAKUZKMGJJMAA-UHFFFAOYSA-N 0.000 claims description 4
- UJMDYLWCYJJYMO-UHFFFAOYSA-N benzene-1,2,3-tricarboxylic acid Chemical compound OC(=O)C1=CC=CC(C(O)=O)=C1C(O)=O UJMDYLWCYJJYMO-UHFFFAOYSA-N 0.000 claims description 4
- QMKYBPDZANOJGF-UHFFFAOYSA-N benzene-1,3,5-tricarboxylic acid Chemical compound OC(=O)C1=CC(C(O)=O)=CC(C(O)=O)=C1 QMKYBPDZANOJGF-UHFFFAOYSA-N 0.000 claims description 4
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 4
- 239000002904 solvent Substances 0.000 claims description 4
- KQTIIICEAUMSDG-UHFFFAOYSA-N tricarballylic acid Chemical compound OC(=O)CC(C(O)=O)CC(O)=O KQTIIICEAUMSDG-UHFFFAOYSA-N 0.000 claims description 4
- ARCGXLSVLAOJQL-UHFFFAOYSA-N trimellitic acid Chemical compound OC(=O)C1=CC=C(C(O)=O)C(C(O)=O)=C1 ARCGXLSVLAOJQL-UHFFFAOYSA-N 0.000 claims description 4
- 125000002887 hydroxy group Chemical group [H]O* 0.000 claims description 3
- 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 2
- YJLYANLCNIKXMG-UHFFFAOYSA-N N-Methyldioctylamine Chemical compound CCCCCCCCN(C)CCCCCCCC YJLYANLCNIKXMG-UHFFFAOYSA-N 0.000 claims description 2
- 229920002125 Sokalan® Polymers 0.000 claims description 2
- 238000007605 air drying Methods 0.000 claims description 2
- LOGBRYZYTBQBTB-UHFFFAOYSA-N butane-1,2,4-tricarboxylic acid Chemical compound OC(=O)CCC(C(O)=O)CC(O)=O LOGBRYZYTBQBTB-UHFFFAOYSA-N 0.000 claims description 2
- 229910052799 carbon Inorganic materials 0.000 claims description 2
- 239000002134 carbon nanofiber Substances 0.000 claims description 2
- 239000002041 carbon nanotube Substances 0.000 claims description 2
- 229910021393 carbon nanotube Inorganic materials 0.000 claims description 2
- 239000011247 coating layer Substances 0.000 claims description 2
- 229910021389 graphene Inorganic materials 0.000 claims description 2
- 239000002086 nanomaterial Substances 0.000 claims description 2
- 239000007773 negative electrode material Substances 0.000 claims description 2
- ROTJZTYLACIJIG-UHFFFAOYSA-N pentane-1,3,5-tricarboxylic acid Chemical compound OC(=O)CCC(C(O)=O)CCC(O)=O ROTJZTYLACIJIG-UHFFFAOYSA-N 0.000 claims description 2
- 239000004584 polyacrylic acid Substances 0.000 claims description 2
- 239000000661 sodium alginate Substances 0.000 claims description 2
- 235000010413 sodium alginate Nutrition 0.000 claims description 2
- 229940005550 sodium alginate Drugs 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 claims 1
- 229920003048 styrene butadiene rubber Polymers 0.000 claims 1
- 239000003607 modifier Substances 0.000 abstract description 17
- 238000001035 drying Methods 0.000 abstract description 15
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 abstract description 9
- 229910001416 lithium ion Inorganic materials 0.000 abstract description 9
- 238000002156 mixing Methods 0.000 abstract description 2
- 125000004122 cyclic group Chemical group 0.000 abstract 1
- 239000006230 acetylene black Substances 0.000 description 8
- 229910052802 copper Inorganic materials 0.000 description 8
- 239000010949 copper Substances 0.000 description 8
- 238000005303 weighing Methods 0.000 description 8
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 4
- 239000002131 composite material Substances 0.000 description 4
- 229910052744 lithium Inorganic materials 0.000 description 4
- 239000010406 cathode material Substances 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000005886 esterification reaction Methods 0.000 description 2
- 235000019441 ethanol Nutrition 0.000 description 2
- 230000002687 intercalation Effects 0.000 description 2
- 238000009830 intercalation Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000013543 active substance Substances 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 239000010405 anode material Substances 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 239000007772 electrode material Substances 0.000 description 1
- 239000007770 graphite material Substances 0.000 description 1
- WGCNASOHLSPBMP-UHFFFAOYSA-N hydroxyacetaldehyde Natural products OCC=O WGCNASOHLSPBMP-UHFFFAOYSA-N 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 239000002048 multi walled nanotube Substances 0.000 description 1
- 150000007519 polyprotic acids Polymers 0.000 description 1
- 238000010298 pulverizing process Methods 0.000 description 1
- 230000008929 regeneration Effects 0.000 description 1
- 238000011069 regeneration method Methods 0.000 description 1
- 150000003384 small molecules Chemical class 0.000 description 1
Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—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
- 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
- H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/134—Electrodes based on metals, Si or alloys
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/139—Processes of manufacture
- H01M4/1393—Processes of manufacture of electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/139—Processes of manufacture
- H01M4/1395—Processes of manufacture of electrodes based on metals, Si or alloys
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—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
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
- H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
- H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
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- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
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- H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
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- 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
Abstract
The invention belongs to the technical field of lithium ion batteries, and particularly relates to a high specific capacity silicon-carbon composite anode material and a preparation method of a pole piece thereof. The high-specific-capacity silicon-carbon composite anode material comprises active ingredients of silicon-coated graphite, a specific surface modifier and nano silicon, wherein the nano silicon forms a covalent bond through the specific surface modifier to be coated on the surface of the silicon-coated graphite; the specific surface modifier is a bridging molecule containing a carboxyl group. The preparation method of the pole piece comprises the following steps: uniformly mixing silicon-coated graphite, a specific surface modifier, nano silicon, a conductive agent and a binder according to a certain proportion, coating the mixture on the surface of a copper foil current collector, and drying and vacuum drying the mixture to obtain the high-specific-capacity silicon-carbon composite negative electrode plate. The silicon-carbon composite anode material and the pole piece preparation method thereof disclosed by the invention have the advantages of simple process and strong practicability, and after the prepared pole piece is assembled into a battery, the initial coulomb efficiency and the cyclic stability are greatly improved, so that the silicon-carbon composite anode material and the pole piece preparation method thereof are suitable for high-energy-density lithium ion batteries.
Description
Technical Field
The invention belongs to the technical field of lithium ion battery electrode materials, and particularly relates to a high specific capacity silicon-carbon composite anode material and a preparation method of a pole piece thereof.
Background
With the rapid development of new energy automobile industry, higher requirements are put forward on the aspects of energy density, cycle life, cost, safety and the like of the lithium ion power battery. However, the energy density of the lithium ion power battery sold in the market at present is low, the requirement of a new energy automobile on long endurance mileage is difficult to meet, and the requirement of the lithium ion battery with high energy density is more urgent.
From the aspect of the cathode material, the current commercial lithium ion battery cathode material is mainly graphite with good circulation stability and conductivity and low cost, but the theoretical specific capacity of the graphite is low and is only 372mAh/g. Compared with graphite, when silicon reaches the maximum lithium intercalation degree at room temperature, the theoretical specific capacity is up to 3579mAh/g, and meanwhile, the lithium intercalation potential of silicon is lower, the source is wide, so that the silicon becomes a potential next-generation lithium ion battery cathode material. However, when silicon is intercalated into lithium, the volume expansion can reach 300%, and serious volume expansion causes the problems of pole piece pulverization, electric insulation of active substances, repeated rupture and regeneration of SEI films, continuous consumption of active lithium and the like, thereby limiting the application of silicon in lithium ion batteries.
For these problems, a simple combination of silicon and graphite is currently used to suppress the volume expansion effect of silicon, but the agglomeration phenomenon of silicon is easy to occur in the combination process of silicon and graphite, resulting in poor cycle stability. Therefore, the invention designs and prepares a novel silicon-carbon composite material. Specifically, the silicon coated on the graphite surface in the composite material can improve the specific capacity of the composite material while not affecting the graphite performance. And the nano silicon on the surface of the graphite can also provide a connecting site, more nano silicon is uniformly/stably bound on the surface of the graphite material through organic small molecule polybasic acid, the proportion of silicon in the negative electrode active material is improved while the circulation stability is ensured, and the energy density of the battery is finally improved.
Disclosure of Invention
In order to improve the charge-discharge specific capacity and the cycle stability of the silicon-carbon composite anode material, the invention provides the silicon-carbon composite anode material with high specific capacity and the preparation method of the pole piece, and the prepared pole piece has the advantages of high specific capacity and high cycle stability.
In order to achieve the above purpose, the invention adopts the following technical scheme:
the invention develops a high specific capacity silicon-carbon composite anode material. The active ingredients of the anode material comprise silicon-coated graphite, nano silicon and bridging molecules containing carboxyl groups. The bridging molecule containing carboxyl groups is used as a specific surface modifier between the silicon-coated graphite and the nano silicon, the specific surface modifier is subjected to esterification reaction with hydroxyl groups on the surface of the silicon through carboxyl groups, covalent bond connection is formed between the silicon-coated graphite and the nano silicon, so that the nano silicon is uniformly coated on the surface of the silicon-coated graphite, and the theoretical specific capacity of the material is improved; meanwhile, the surface modifier can form covalent bonds between the nano silicon and the nano silicon, so that the volume expansion of the silicon is inhibited, and the structural stability of the material is improved. When the addition amount of the surface modifier is large, the surface modifier can be independently used as a binder to form a firm three-dimensional network structure in the pole piece, so that the cycle stability of the battery is effectively improved.
Preferably, the silicon in the silicon-coated graphite is combined with the graphite in the form of a coating or coated particles, wherein the silicon content is 0.1% -10%; the thickness of the coating layer or the size of the coated particles is less than 100nm.
Preferably, the carbon content of the nano silicon is 0-2%, the nano silicon has a zero-dimensional, one-dimensional or two-dimensional nano structure, and the content of the nano silicon is 0.1% -20% of the total mass of the silicon-carbon composite anode material.
The invention also provides a preparation method of the high specific capacity silicon-carbon composite negative electrode plate, which comprises the following steps: and fully stirring and mixing the silicon-coated graphite, the specific surface modifier, the nano silicon, the conductive agent, the adhesive and the solvent according to a certain proportion, uniformly coating the mixture on the surface of the copper foil current collector, and drying the mixture in vacuum after forced air drying to obtain the silicon-carbon composite negative electrode plate.
More preferably, the specific surface modifier forms covalent bonds between the silicon-coated graphite and the nano silicon and between the nano silicon and the nano silicon through esterification reaction, so that the nano silicon is uniformly coated on the surface of the silicon-coated graphite.
More preferably, the total mass is the mass sum of the silicon-coated graphite, the specific surface modifier, the nano silicon, the conductive agent and the binder, wherein the silicon-coated graphite accounts for 74-85% of the total mass, the specific surface modifier accounts for 1-10% of the total mass, the nano silicon accounts for 5-20% of the total mass, and the silicon-carbon composite anode material comprising the silicon-coated graphite, the nano silicon and the specific surface modifier accounts for 80-95% of the total mass; the mass of the conductive agent is 2-10% of the total mass, and the mass of the binder is 0-10% of the total mass.
More preferably, the specific surface modifier is at least one of 1,2,4, 5-benzene tetracarboxylic acid, 1,2,4, 5-cyclohexane tetracarboxylic acid, 1,2,3, 4-butane tetracarboxylic acid, 1,2, 3-benzene tricarboxylic acid, 1,2, 4-benzene tricarboxylic acid, 1,3, 5-benzene tricarboxylic acid, 1,2, 3-propane tricarboxylic acid, 1,2, 4-butane tricarboxylic acid, 1,3, 5-pentane tricarboxylic acid, 1,3, 5-cyclohexane tricarboxylic acid, preferably 1,2,4, 5-benzene tetracarboxylic acid, 1,2,4, 5-cyclohexane tetracarboxylic acid and 1,2,3, 4-butane tetracarboxylic acid.
More preferably, the conductive agent is at least one of conductive carbon black, carbon nanotubes, carbon nanofibers and graphene, and the binder is at least one of sodium carboxymethyl cellulose, polyacrylic acid and sodium alginate.
More preferably, the solvent is at least one of water, ethanol and glycol, and preferably an ethanol aqueous solution with a mass fraction of 20% -60%.
More preferably, the particle size of the nano silicon is 20 nm-200 nm, and the surface of the nano silicon is rich in hydroxyl groups.
Compared with the prior art, the invention has the beneficial effects that:
1. the specific surface modifier used in the invention forms a covalent bond between the nano silicon and the silicon coated graphite, so that the nano silicon is uniformly coated on the surface of the silicon coated graphite, and the specific capacity of the composite material is improved.
2. The specific surface modifier used in the invention can inhibit the volume expansion effect of silicon and improve the cycle stability of the composite material while bridging graphite and silicon.
Detailed description of the preferred embodiments
Comparative example 1
Respectively weighing 0.7g of graphite (without silicon), 0.1g of nano silicon, 0.05g of sodium carboxymethylcellulose and 0.1g of acetylene black, adding 4ml of deionized water and 2ml of absolute ethyl alcohol, magnetically stirring for 12 hours, finally adding 0.05g of SBR, stirring for 1 hour, uniformly coating on the surface of a copper current collector, drying at 60 ℃ for 30 minutes, and then drying at 120 ℃ in a vacuum drying oven for 12 hours; finally, slicing and preparing the button half-cell, and testing at room temperature and current density of 200mA/g, wherein the testing voltage range is 0.01-1.5V. The results of the sample testing are shown in table 1.
Example 1
Respectively weighing 0.7g of silicon-coated graphite, 0.1g of nano silicon, 0.05g of 1,2,4, 5-benzene tetracarboxylic acid, 0.025g of sodium carboxymethyl cellulose and 0.1g of acetylene black, adding 4ml of deionized water and 2ml of absolute ethyl alcohol, magnetically stirring for 12 hours, finally adding 0.025g of SBR, stirring for 1 hour, uniformly coating on the surface of a copper current collector, drying at 60 ℃ for 30 minutes, and then drying in a vacuum drying oven at 120 ℃ for 12 hours; finally, slicing and preparing the button half-cell, and testing at room temperature and current density of 200mA/g, wherein the testing voltage range is 0.01-1.5V. The results of the sample testing are shown in table 1.
Example 2
Respectively weighing 0.7g of silicon-coated graphite, 0.1g of nano silicon, 0.05g of 1,2,4, 5-cyclohexane tetracarboxylic acid, 0.025g of sodium carboxymethyl cellulose and 0.1g of acetylene black, adding 4ml of deionized water and 2ml of absolute ethyl alcohol, magnetically stirring for 12 hours, finally adding 0.025g of SBR, stirring for 1 hour, uniformly coating on the surface of a copper current collector, drying at 60 ℃ for 30 minutes, and vacuum-drying at 120 ℃ in a vacuum drying oven for 12 hours; finally, slicing and preparing the button half-cell, and testing at room temperature and current density of 200mA/g, wherein the testing voltage range is 0.01-1.5V. The results of the sample testing are shown in table 1.
Example 3
Respectively weighing 0.7g of silicon-coated graphite, 0.1g of nano silicon, 0.05g of 1,2,3, 4-butane tetracarboxylic acid, 0.025g of sodium carboxymethyl cellulose and 0.1g of acetylene black, adding 4ml of deionized water and 2ml of absolute ethyl alcohol, magnetically stirring for 12 hours, finally adding 0.025g of SBR, stirring for 1 hour, uniformly coating on the surface of a copper current collector, drying at 60 ℃ for 30 minutes, and vacuum-drying at 120 ℃ in a vacuum drying oven for 12 hours; finally, slicing and preparing the button half-cell, and testing at room temperature and current density of 200mA/g, wherein the testing voltage range is 0.01-1.5V. The results of the sample testing are shown in table 1.
Example 4
Respectively weighing 0.7g of silicon-coated graphite, 0.1g of nano silicon, 0.05g of 1,2,4, 5-benzene tetracarboxylic acid, 0.025g of sodium carboxymethyl cellulose, 0.09g of acetylene black and 0.01g of multi-wall carbon nano tube, adding 4ml of deionized water and 2ml of absolute ethyl alcohol, magnetically stirring for 12 hours, finally adding 0.025g of SBR, stirring for 1 hour, uniformly coating on the surface of a copper current collector, drying at 60 ℃ for 30 minutes, and then drying at 120 ℃ in a vacuum drying oven for 12 hours; finally, slicing and preparing the button half-cell, and testing at room temperature and current density of 200mA/g, wherein the testing voltage range is 0.01-1.5V. The results of the sample testing are shown in table 1.
Example 5
Respectively weighing 0.7g of silicon-coated graphite, 0.1g of nano silicon, 0.1g of 1,2,4, 5-benzene tetracarboxylic acid and 0.1g of acetylene black, adding 4ml of deionized water and 2ml of absolute ethyl alcohol, magnetically stirring for 12 hours, uniformly coating the surfaces of copper current collectors, drying at 60 ℃ for 30 minutes, and then drying in a vacuum drying oven at 120 ℃ for 12 hours; finally, slicing and preparing the button half-cell, and testing at room temperature and current density of 200mA/g, wherein the testing voltage range is 0.01-1.5V. The results of the sample testing are shown in table 1.
Comparative example 2
Respectively weighing 0.6g of graphite (without silicon), 0.2g of nano silicon, 0.05g of sodium carboxymethylcellulose and 0.1g of acetylene black, adding 4ml of deionized water and 2ml of absolute ethyl alcohol, magnetically stirring for 12 hours, finally adding 0.05g of SBR, stirring for 1 hour, uniformly coating on the surface of a copper current collector, drying at 60 ℃ for 30 minutes, and then drying at 120 ℃ in a vacuum drying oven for 12 hours; finally, slicing and preparing the button half-cell, and testing at room temperature and current density of 200mA/g, wherein the testing voltage range is 0.01-1.5V. The results of the sample testing are shown in table 1.
Example 6
Respectively weighing 0.6g of silicon-coated graphite, 0.2g of nano silicon, 0.05g of 1,2,4, 5-benzene tetracarboxylic acid, 0.025g of sodium carboxymethyl cellulose and 0.1g of acetylene black, adding 4ml of deionized water and 2ml of absolute ethyl alcohol, magnetically stirring for 12 hours, finally adding 0.025g of SBR, stirring for 1 hour, uniformly coating on the surface of a copper current collector, drying at 60 ℃ for 30 minutes, and vacuum drying at 120 ℃ in a vacuum drying oven for 12 hours; finally, slicing and preparing the button half-cell, and testing at room temperature and current density of 200mA/g, wherein the testing voltage range is 0.01-1.5V. The results of the sample testing are shown in table 1.
Table 1 comparison of electrochemical properties of different samples
Claims (10)
1. A high specific capacity silicon-carbon composite negative electrode material is characterized in that: the active ingredients of the negative electrode material comprise silicon-coated graphite, nano silicon and bridging molecules containing carboxyl groups, wherein the carboxyl groups of the bridging molecules are respectively combined with the silicon on the surface of the graphite and the nano silicon through covalent bonds, so that the nano silicon is uniformly distributed on the surface of the silicon-coated graphite.
2. The high specific capacity silicon-carbon composite anode material according to claim 1, wherein: the silicon in the silicon-coated graphite is combined with the graphite in a coating or coated particle form, wherein the content of the silicon is 0.1% -10%; the thickness of the coating layer or the size of the coated particles is less than 100nm.
3. The high specific capacity silicon-carbon composite anode material according to claim 1, wherein: the carbon content of the nano silicon is 0-2%, the nano silicon has a zero-dimensional, one-dimensional or two-dimensional nano structure, and the content of the nano silicon is 0.1% -20% of the total mass of the silicon-carbon composite anode material; the particle size of the nano silicon is 20 nm-200 nm, and the surface of the nano silicon contains hydroxyl.
4. The high specific capacity silicon-carbon composite anode material according to claim 1, wherein: the bridging molecule is at least one of 1,2,4, 5-benzene tetracarboxylic acid, 1,2,4, 5-cyclohexane tetracarboxylic acid, 1,2,3, 4-butane tetracarboxylic acid, 1,2, 3-benzene tricarboxylic acid, 1,2, 4-benzene tricarboxylic acid, 1,3, 5-benzene tricarboxylic acid, 1,2, 3-propane tricarboxylic acid, 1,2, 4-butane tricarboxylic acid, 1,3, 5-pentane tricarboxylic acid and 1,3, 5-cyclohexane tricarboxylic acid.
5. A preparation method of a high specific capacity silicon-carbon composite negative electrode plate is characterized by comprising the following steps: fully and uniformly stirring a silicon-carbon composite anode material, a conductive agent and a solvent according to a certain proportion, coating the mixture on the surface of a copper foil current collector, and carrying out forced air drying and vacuum drying to obtain a high-specific-capacity silicon-carbon composite anode piece; the silicon-carbon composite anode material is the high specific capacity silicon-carbon composite anode material according to any one of claims 1 to 4.
6. The method for preparing the high-specific-capacity silicon-carbon composite negative electrode plate, which is characterized by comprising the following steps of: the silicon-carbon composite anode material can play a role in bonding; when the addition amount of bridging molecules in the silicon-carbon composite anode material is small, an additional binder needs to be added.
7. The method for preparing the high-specific-capacity silicon-carbon composite negative electrode plate, which is characterized by comprising the following steps of: the total mass of the silicon-carbon composite anode material, the conductive agent and the binder is 80-95%, the conductive agent is 2-10% and the binder is 0-10%.
8. The method for preparing the high-specific-capacity silicon-carbon composite negative electrode plate according to claim 5 or 7, which is characterized by comprising the following steps: taking the mass sum of the silicon-carbon composite anode material, the conductive agent and the binder as the total mass, wherein the silicon-coated graphite accounts for 74-85% of the total mass, the bridging molecule accounts for 1-10% of the total mass, and the nano silicon accounts for 5-20% of the total mass.
9. The method for preparing the high-specific-capacity silicon-carbon composite negative electrode plate, which is characterized by comprising the following steps of: the conductive agent is at least one of conductive carbon black, carbon nano tubes, carbon nano fibers and graphene; the binder is at least one of sodium carboxymethyl cellulose, polyacrylic acid, sodium alginate and styrene-butadiene rubber; the solvent is at least one of deionized water, ethanol and ethylene glycol.
10. The high specific capacity silicon-carbon composite negative electrode sheet produced by the production method of any one of claims 5 to 9.
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