CN114628684B - High-energy-density quick-charging graphite composite material and preparation method thereof - Google Patents
High-energy-density quick-charging graphite composite material and preparation method thereof Download PDFInfo
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 87
- 229910002804 graphite Inorganic materials 0.000 title claims abstract description 87
- 239000010439 graphite Substances 0.000 title claims abstract description 87
- 239000002131 composite material Substances 0.000 title claims abstract description 51
- 238000002360 preparation method Methods 0.000 title claims abstract description 15
- 229910003481 amorphous carbon Inorganic materials 0.000 claims abstract description 15
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 14
- 239000010703 silicon Substances 0.000 claims abstract description 14
- 238000010438 heat treatment Methods 0.000 claims description 19
- 239000006087 Silane Coupling Agent Substances 0.000 claims description 16
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 12
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 12
- 229910052782 aluminium Inorganic materials 0.000 claims description 12
- 238000010000 carbonizing Methods 0.000 claims description 11
- 238000001291 vacuum drying Methods 0.000 claims description 11
- 238000003756 stirring Methods 0.000 claims description 10
- 238000002156 mixing Methods 0.000 claims description 9
- XNDZQQSKSQTQQD-UHFFFAOYSA-N 3-methylcyclohex-2-en-1-ol Chemical compound CC1=CC(O)CCC1 XNDZQQSKSQTQQD-UHFFFAOYSA-N 0.000 claims description 8
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims description 7
- 230000032683 aging Effects 0.000 claims description 6
- WNROFYMDJYEPJX-UHFFFAOYSA-K aluminium hydroxide Chemical compound [OH-].[OH-].[OH-].[Al+3] WNROFYMDJYEPJX-UHFFFAOYSA-K 0.000 claims description 6
- 239000012298 atmosphere Substances 0.000 claims description 6
- 238000000498 ball milling Methods 0.000 claims description 6
- 239000012299 nitrogen atmosphere Substances 0.000 claims description 6
- 239000002243 precursor Substances 0.000 claims description 6
- VZGDMQKNWNREIO-UHFFFAOYSA-N tetrachloromethane Chemical compound ClC(Cl)(Cl)Cl VZGDMQKNWNREIO-UHFFFAOYSA-N 0.000 claims description 6
- 238000006243 chemical reaction Methods 0.000 claims description 5
- 238000000227 grinding Methods 0.000 claims description 5
- 238000001694 spray drying Methods 0.000 claims description 5
- XDTMQSROBMDMFD-UHFFFAOYSA-N Cyclohexane Chemical compound C1CCCCC1 XDTMQSROBMDMFD-UHFFFAOYSA-N 0.000 claims description 4
- 239000004111 Potassium silicate Substances 0.000 claims description 4
- 239000003513 alkali Substances 0.000 claims description 4
- NNHHDJVEYQHLHG-UHFFFAOYSA-N potassium silicate Chemical compound [K+].[K+].[O-][Si]([O-])=O NNHHDJVEYQHLHG-UHFFFAOYSA-N 0.000 claims description 4
- 229910052913 potassium silicate Inorganic materials 0.000 claims description 4
- 235000019353 potassium silicate Nutrition 0.000 claims description 4
- 238000004321 preservation Methods 0.000 claims description 4
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 claims description 3
- 239000004115 Sodium Silicate Substances 0.000 claims description 3
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 claims description 3
- 229910052911 sodium silicate Inorganic materials 0.000 claims description 3
- 150000007530 organic bases Chemical class 0.000 claims description 2
- 239000003960 organic solvent Substances 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 claims 3
- 239000000463 material Substances 0.000 abstract description 19
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 abstract description 9
- 239000011258 core-shell material Substances 0.000 abstract description 3
- 150000003377 silicon compounds Chemical class 0.000 abstract description 3
- 239000000243 solution Substances 0.000 description 28
- 230000000052 comparative effect Effects 0.000 description 15
- ZMANZCXQSJIPKH-UHFFFAOYSA-N Triethylamine Chemical compound CCN(CC)CC ZMANZCXQSJIPKH-UHFFFAOYSA-N 0.000 description 12
- 238000012360 testing method Methods 0.000 description 12
- 239000007773 negative electrode material Substances 0.000 description 11
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 10
- 239000003792 electrolyte Substances 0.000 description 10
- 239000007788 liquid Substances 0.000 description 10
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 7
- 238000010521 absorption reaction Methods 0.000 description 6
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 5
- 229940024545 aluminum hydroxide Drugs 0.000 description 5
- 229910052786 argon Inorganic materials 0.000 description 5
- 229910001416 lithium ion Inorganic materials 0.000 description 5
- 230000014759 maintenance of location Effects 0.000 description 5
- 229910013870 LiPF 6 Inorganic materials 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- 239000002245 particle Substances 0.000 description 4
- 239000000047 product Substances 0.000 description 4
- 239000002210 silicon-based material Substances 0.000 description 4
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical group O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 description 3
- 229910021383 artificial graphite Inorganic materials 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- OIFBSDVPJOWBCH-UHFFFAOYSA-N Diethyl carbonate Chemical compound CCOC(=O)OCC OIFBSDVPJOWBCH-UHFFFAOYSA-N 0.000 description 2
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 2
- UIIMBOGNXHQVGW-UHFFFAOYSA-M Sodium bicarbonate Chemical compound [Na+].OC([O-])=O UIIMBOGNXHQVGW-UHFFFAOYSA-M 0.000 description 2
- 239000003575 carbonaceous material Substances 0.000 description 2
- 238000003763 carbonization Methods 0.000 description 2
- 239000010406 cathode material Substances 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 235000019441 ethanol Nutrition 0.000 description 2
- 238000011049 filling Methods 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 239000011259 mixed solution Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 229910021426 porous silicon Inorganic materials 0.000 description 2
- 238000007086 side reaction Methods 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- 238000003860 storage Methods 0.000 description 2
- 238000010998 test method Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 238000005303 weighing Methods 0.000 description 2
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- BOTDANWDWHJENH-UHFFFAOYSA-N Tetraethyl orthosilicate Chemical compound CCO[Si](OCC)(OCC)OCC BOTDANWDWHJENH-UHFFFAOYSA-N 0.000 description 1
- 239000004964 aerogel Substances 0.000 description 1
- 229940024546 aluminum hydroxide gel Drugs 0.000 description 1
- -1 aluminum nitrate nonahydrate ethanol Chemical compound 0.000 description 1
- SMYKVLBUSSNXMV-UHFFFAOYSA-K aluminum;trihydroxide;hydrate Chemical compound O.[OH-].[OH-].[OH-].[Al+3] SMYKVLBUSSNXMV-UHFFFAOYSA-K 0.000 description 1
- 239000010405 anode material Substances 0.000 description 1
- 239000012300 argon atmosphere Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000011247 coating layer Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000001351 cycling effect Effects 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 229910021641 deionized water Inorganic materials 0.000 description 1
- IJKVHSBPTUYDLN-UHFFFAOYSA-N dihydroxy(oxo)silane Chemical compound O[Si](O)=O IJKVHSBPTUYDLN-UHFFFAOYSA-N 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 239000008151 electrolyte solution Substances 0.000 description 1
- 239000007770 graphite material Substances 0.000 description 1
- 229910003474 graphite-silicon composite material Inorganic materials 0.000 description 1
- 230000003301 hydrolyzing effect Effects 0.000 description 1
- 239000010410 layer Substances 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 150000002894 organic compounds Chemical class 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 239000012466 permeate Substances 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 229910000028 potassium bicarbonate Inorganic materials 0.000 description 1
- 235000015497 potassium bicarbonate Nutrition 0.000 description 1
- 239000011736 potassium bicarbonate Substances 0.000 description 1
- TYJJADVDDVDEDZ-UHFFFAOYSA-M potassium hydrogencarbonate Chemical compound [K+].OC([O-])=O TYJJADVDDVDEDZ-UHFFFAOYSA-M 0.000 description 1
- 238000001878 scanning electron micrograph Methods 0.000 description 1
- 239000002153 silicon-carbon composite material Substances 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 229910000030 sodium bicarbonate Inorganic materials 0.000 description 1
- 235000017557 sodium bicarbonate Nutrition 0.000 description 1
- 229910000029 sodium carbonate Inorganic materials 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
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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
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
-
- 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
- H01M4/36—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
- H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
- H01M4/483—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides for non-aqueous cells
-
- 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
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
- H01M2004/027—Negative electrodes
-
- 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 discloses a high-energy density quick-charging graphite composite material and a preparation method thereof, wherein the composite material has a core-shell structure, the core is a silicon-doped graphite complex, and the shell is amorphous carbon containing porous alumina; the mass of the shell is 1-10% based on 100% of the total mass of the composite material. Wherein in the inner core, the silicon is SiO X (X is more than 0 and less than 2) the mass ratio of the silicon compound to the inner core is 1-10%. According to the invention, when the energy density of the material is improved by doping silicon in the porous graphite, the porous alumina in the shell has a high specific surface area, so that the impedance is reduced, and the quick charging performance of the material is improved.
Description
Technical Field
The invention belongs to the technical field of lithium ion battery materials, particularly relates to a high-energy-density quick-charging graphite composite material, and also relates to a preparation method of the high-energy-density quick-charging graphite composite material.
Background
With the improvement of the energy density requirement of the lithium ion battery in the market, the fast charging performance is also improved while the lithium ion battery cathode material is required to have high energy density. The current graphite material has good quick charging performance, but has low energy density; although the silicon-based material has high energy density, the silicon-based material has the defects of poor quick charge performance, large expansion, poor high-temperature storage and the like. One of the measures for improving the energy density and the quick charge performance of the cathode material is to mix the carbon-based material and the silicon-based material to play a synergistic effect between the carbon-based material and the silicon-based material, although the two types of materials are mixed in the market, the materials belong to physical mixing, the uniformity is poor, the impedance is large, and the surface of the materials is not treated and modified, so that the improvement range of the charging capability is small; for example, chinese patent CN201811642943.9 discloses a silicon/expanded graphite/amorphous carbon composite material and a preparation method thereof, wherein tetraethoxysilane, absolute ethyl alcohol and deionized water are mixedTo prepare SiO 2 Mixing the aerogel blocky solid with magnesium powder, and heating in an argon atmosphere to obtain nano porous silicon; and then mixing and coating the nano porous silicon and the expanded graphite in ethanol to obtain the silicon/expanded graphite/amorphous carbon composite material. Although the expansion is improved, the surface of the material is not coated and modified, so that side reactions with electrolyte are more, and the storage performance, the cycle performance and the power performance of the material are reduced.
Disclosure of Invention
The invention aims to overcome the defects and provide a high-energy-density quick-charging graphite composite material which can improve the energy density of the material and improve the quick charging performance of the material.
The invention also aims to provide a preparation method of the high-energy-density quick-charging graphite composite material.
The invention relates to a high-energy-density quick-filling graphite composite material, wherein the composite material is in a core-shell structure, an inner core is a silicon-doped graphite complex, and an outer shell is amorphous carbon containing porous alumina; the mass of the shell is 1-10% calculated by the total mass of the composite material 100%.
In the core, silicon is SiO X (X is more than 0 and less than 2) the mass ratio of the silicon compound to the inner core is 1-10%.
The invention relates to a preparation method of a high-energy-density quick-filling graphite composite material, which comprises the following steps:
(1) mixing graphite and 1-10 wt% of aqueous alkali at normal temperature, stirring and reacting for 12h, centrifuging the product, vacuum drying at 80 ℃ for 6h and carbonizing at 800 ℃ for 3h, grinding and crushing to obtain porous graphite, adding the porous graphite into 1-10 wt% of inorganic silicon solution, and adding a silane coupling agent, wherein the weight ratio of porous graphite: inorganic silicon: the mass ratio of the silane coupling agent is 90-95: 5-10: 1-5, spray drying, and carbonizing at 700-1000 ℃ for 1-6 h in an inert atmosphere to obtain a silicon-doped graphite complex;
(2) dispersing the silicon-doped graphite complex in an organic solution to prepare a solution with the mass concentration of 1-10%, uniformly stirring, dropwise adding a solution of aluminum nitrate nonahydrate, wherein the silicon-doped graphite complex comprises the following components in percentage by mass: the mass ratio of the aluminum nitrate nonahydrate is 100: 10-30; and then, dropwise adding organic base to adjust the pH value to 5-8, reacting at room temperature for 1-12 h to form aluminum sol, heating to 50-100 ℃, carrying out aging reaction for 6-24 h to form aluminum gel, carrying out vacuum drying and ball milling, placing the obtained aluminum hydroxide coated graphite precursor in a vacuum tube furnace, heating to 700-1000 ℃ under the nitrogen atmosphere, wherein the heating rate is 1-5 ℃/min, and the heat preservation time is 1-6 h, so as to obtain the aluminum oxide/amorphous carbon coated graphite composite material, namely the high-energy-density quick-charging graphite composite material.
The preparation method of the high-energy-density quick-charging graphite composite material comprises the following steps: the inorganic silicon solution in the step (1) is one of potassium silicate solution or sodium silicate solution;
the preparation method of the high-energy-density quick-charging graphite composite material comprises the following steps: the silane coupling agent in the step (1) is one of a silane coupling agent KH550, a silane coupling agent KH560 or a silane coupling agent KH 570.
The preparation method of the high-energy-density quick-charging graphite composite material comprises the following steps: in the step (2), the organic solvent is one of cyclohexane, N-methyl pyrrolidone or carbon tetrachloride.
Compared with the prior art, the invention has obvious beneficial effects, and the technical scheme can show that: the preparation method comprises the steps of preparing an inner core of a silicon-doped graphite complex by a chemical method, coating amorphous carbon of porous alumina on the surface of the inner core, hydrolyzing aluminum nitrate nonahydrate under an alkaline condition to generate aluminum hydroxide gel, sintering to generate porous alumina, and finally obtaining a coating layer of which the outer layer contains the porous alumina and the amorphous carbon by using amorphous carbon formed by carbonizing an organic compound; and the contact between the aluminum oxide and the electrolyte is inert, so that the first efficiency of the material is improved, and the energy density of the battery is indirectly improved. The porous structure improves the transmission rate of lithium ions in the charging and discharging process and improves the multiplying power performance. The graphite reacts with alkali, the alkali compound is decomposed after carbonization to obtain the porous graphite composite material, and the silicate solution permeates into the porous structure and reacts with the silane coupling agent to be carbonized to form the silicon compound material with a network structure, wherein the network structure can reduce the expansion of doped silicon and reduce the impedance.
Drawings
Fig. 1 is an SEM image of the alumina/amorphous carbon-coated graphite composite obtained in example 1.
Detailed Description
Example 1
A preparation method of a high-energy-density quick-charging graphite composite material comprises the following steps:
(1) mixing 10g of graphite with 500ml of 5% sodium carbonate solution, stirring, reacting for 12 hours, centrifuging the product, vacuum drying at 80 ℃ for 6 hours, carbonizing at 800 ℃ for 3 hours, and grinding and crushing to obtain porous graphite; adding 92g of porous graphite into 100ml of 4 wt% potassium silicate solution, adding 4g of KH550 silane coupling agent, spray-drying, and carbonizing at 800 ℃ for 3h under argon inert atmosphere to obtain a silicon-doped graphite composite;
(2) dispersing 100g of the silicon-doped graphite complex in 2000ml of cyclohexane organic solution to prepare a solution with the mass concentration of 5%, uniformly stirring, dropwise adding 200ml of ethanol solution of 10wt% of aluminum nitrate nonahydrate, dropwise adding triethylamine to adjust the pH value to 6, reacting at room temperature for 6h to form aluminum sol, heating to 80 ℃, aging to react for 12h to form aluminum gel, vacuum drying at 80 ℃ for 24h, ball-milling, placing the obtained aluminum hydroxide coated graphite precursor in a vacuum tube furnace, heating to 850 ℃ under the nitrogen atmosphere, heating at the rate of 3 ℃/min, and keeping the temperature for 3h to obtain the aluminum oxide/amorphous carbon coated graphite composite material.
Example 2
A preparation method of a high-energy-density quick-charging graphite composite material comprises the following steps:
(1) mixing and stirring 100g of artificial graphite with 500ml of 1% potassium bicarbonate solution, reacting for 12 hours, centrifuging the product, carrying out vacuum drying at 80 ℃ for 6 hours and carbonizing at 800 ℃ for 3 hours, grinding and crushing to obtain porous graphite, adding 90g of porous graphite into 500ml of 1 wt% potassium silicate solution, adding 5g of silane coupling agent KH570, carrying out spray drying, and carbonizing at 700 ℃ for 6 hours under argon inert atmosphere to obtain a silicon-doped graphite composite;
(2) dispersing 100g of the silicon-doped graphite complex in 10000ml of N-methyl pyrrolidone solution to prepare a solution with the mass concentration of 1%, uniformly stirring, dropwise adding 100ml of a solution of 10wt% of aluminum nitrate nonahydrate, dropwise adding triethylamine to adjust the pH value to 5, reacting at room temperature for 1h to form aluminum sol, heating to 100 ℃, carrying out aging reaction for 6h to form aluminum gel, carrying out vacuum drying at 80 ℃ for 24h, carrying out ball milling, placing the obtained aluminum hydroxide coated graphite precursor in a vacuum tube furnace, heating to 700 ℃ under the nitrogen atmosphere, wherein the heating rate is 1 ℃/min, and the heat preservation time is 6h, thus obtaining the aluminum oxide/amorphous carbon coated graphite composite material.
Example 3
A preparation method of a high-energy-density quick-charging graphite composite material comprises the following steps:
(1) mixing and stirring 100g of artificial graphite with 500ml of 10wt% sodium bicarbonate solution, reacting for 12h, centrifuging the product, carrying out vacuum drying at 80 ℃ for 6h and carbonizing at 800 ℃ for 3h, grinding and crushing to obtain porous graphite, adding 95g of porous graphite into 40ml of 10wt% sodium silicate solution, adding 1g of silane coupling agent KH570, carrying out spray drying, and carbonizing at 1000 ℃ for 6h under an argon inert atmosphere to obtain a silicon-doped graphite composite;
(2) dispersing 100g of graphite complex in 1000ml of carbon tetrachloride organic solution to prepare 10% solution with mass concentration, uniformly stirring, dropwise adding 300ml of 10wt% aluminum nitrate nonahydrate solution, dropwise adding triethylamine to adjust the pH value to 8, reacting at room temperature for 12h to form aluminum sol, heating to 50 ℃, aging to react for 24h to form aluminum gel, vacuum drying at 80 ℃ for 24h, ball milling, placing the obtained aluminum hydroxide coated graphite precursor in a vacuum tube furnace, heating to 1000 ℃ under nitrogen atmosphere, heating at the rate of 5 ℃/min, and keeping the temperature for 1h to obtain the aluminum oxide/amorphous carbon coated graphite composite material.
Comparative example 1:
100g of the silicon-doped graphite composite prepared in example 1 was taken, 10g of pitch was added and mixed uniformly, and then the mixture was heated to 800 ℃ in an argon inert atmosphere for carbonization for 3 hours and crushed to obtain an amorphous carbon-coated silicon graphite composite material.
Comparative example 2:
100g of artificial graphite is dispersed in 2000ml of cyclohexane organic solution to prepare a solution with the mass concentration of 5 percent, and the solution is mechanically stirred uniformly; then 200ml of 10wt% aluminum nitrate nonahydrate ethanol solution is dripped; then triethylamine is added dropwise to adjust the pH value to 6, and the mixture reacts for 6 hours at room temperature to form aluminum sol; and finally, heating to 80 ℃, carrying out aging reaction for 12h to form aluminum gel, carrying out vacuum drying for 24h at 80 ℃, carrying out ball milling, then placing the obtained aluminum hydroxide coated graphite precursor in a vacuum tube furnace, heating to 850 ℃ under the nitrogen atmosphere, wherein the heating rate is 3 ℃/min, and the heat preservation time is 3h, thus obtaining the aluminum oxide/amorphous carbon coated graphite composite material.
Test examples
(1) SEM test
The graphite composite anode material prepared in example 1 was subjected to SEM test, and the results are shown in fig. 1.
As can be seen from figure 1, the material has a core-shell structure, the particle size is between 10 and 15 mu m, and the particle size distribution is reasonable.
(2) Physical and chemical property test
The conductivity, tap density, specific surface area and particle size of the graphite composite negative electrode materials in the examples 1-3 and the comparative examples 1-2 are tested according to the test method in the standard GB/T-2433and 2019 graphite type negative electrode materials of lithium ion batteries. The test results are shown in table 1.
TABLE 1
| Negative electrode active material | Example 1 | Example 2 | Example 3 | Comparative example 1 | Comparative example 2 |
| Conductivity (cm/S) | 5.4*10 -9 | 3.9*10 -9 | 1.2*10 -9 | 1.1*10 -10 | 1*10 -10 |
| Tap density (g/cm) 3 ) | 0.98 | 0.97 | 0.96 | 0.90 | 0.89 |
| Specific surface area (m) 2 /g) | 4.2 | 4.1 | 4.0 | 1.7 | 1.3 |
| Particle size (. mu.m) | 11.2 | 11.7 | 12.1 | 11.6 | 12.8 |
As can be seen from table 1, the electrical conductivity of the graphite composite negative electrode materials prepared in examples 1 to 3 is significantly higher than that of comparative example 1, which may be caused by the porous structure, the large specific surface area and the high electrical conductivity of the example materials; meanwhile, the porous alumina can be combined with the core graphite through chemical bonds due to chemical reaction, so that the impedance is lower, and the tap density can be improved.
(3) Button cell test
The graphite composite negative electrode materials prepared in examples 1 to 3 and the graphite composite negative electrode materials of comparative examples 1 to 2 were assembled into button cells, respectively, as follows:
the graphite composite negative electrode materials prepared in examples 1-3 and comparative examples 1-2 are used as negative electrodes and assembled into button cells together with lithium sheets, electrolyte and a diaphragm in a glove box with the content of argon and water lower than 0.1 ppm. Wherein the diaphragm is celegard 2400; the electrolyte is LiPF 6 In the electrolyte solution of (1), LiPF 6 Is 1mol/L, and the solvent is Ethylene Carbonate (EC) and diethyl carbonate (DMC) according to the weight ratio of 1:1 mixing the resulting mixed solution.
Marking the prepared button cells as A-1, B-1, C-1, D-1 and E-1 respectively, and testing the performance of the button cells by adopting a blue tester under the following test conditions: charging and discharging at 0.1C rate, and cycling for 3 weeks at a voltage range of 0.05-2V. The test results are shown in table 2.
TABLE 2
As can be seen from table 2, the button cells prepared using the graphite composite negative electrode materials of examples 1-3 have significantly higher discharge capacities and efficiencies than those of comparative examples 1-2. The experimental result shows that the graphite composite negative electrode material can enable the battery to have good discharge capacity and first efficiency; the silicon is doped in the porous graphite to improve the specific capacity of the material, and the surface of the porous graphite is coated with the porous alumina, so that the expansion of the silicon in the charge and discharge process is reduced, and the first efficiency is improved.
(4) Laminate polymer battery performance test
The graphite composite negative electrodes of examples 1 to 3 and comparative examples 1 to 2 were used as negative electrode active materials, and ternary materials (LiN) were used as positive electrode active materialsi 1/3 Co 1/3 Mn 1/3 O 2 ) The electrolyte and the diaphragm are assembled into the 5Ah soft package battery.
Wherein the diaphragm is celegard 2400, and the electrolyte is LiPF 6 Solution (solvent is mixed solution of EC and DEC with volume ratio of 1:1, LiPF 6 The concentration of (1.3 mol/L). And marking the prepared soft package batteries as A-2, B-2, C-2, D-2 and E-2 respectively.
In examples 1-3 and comparative examples 1-2, 5Ah soft-package batteries and corresponding negative electrode plates thereof were prepared, and the liquid absorption and retention capacity and cycle performance of the negative electrode plates thereof were tested, and the results are shown in tables 3-4. The test method is as follows:
1) liquid absorption capacity:
and (3) adopting a 1mL burette, sucking the electrolyte VmL, dripping a drop on the surface of the pole piece, timing until the electrolyte is completely absorbed, recording the time t, and calculating the liquid absorption speed V/t of the pole piece. The test results are shown in table 3.
2) And (4) testing the liquid retention rate:
calculating the theoretical liquid absorption amount m1 of the pole piece according to the pole piece parameters, weighing the weight m2 of the pole piece, then placing the pole piece into electrolyte to be soaked for 24 hours, weighing the weight m3 of the pole piece, calculating the liquid absorption amount m3-m2 of the pole piece, and calculating according to the following formula: the liquid retention rate was (m3-m2) × 100%/m 1.
3) Cycle performance: testing the cycle performance of the battery at the temperature of 25 +/-3 ℃ with the charge-discharge multiplying power of 1C/1C and the voltage range of 2.5V-4.2V;
TABLE 3
As can be seen from Table 3, the liquid absorbing and retaining capabilities of the silicon-carbon composite materials obtained in examples 1-3 are significantly higher than those of the comparative examples, i.e., the graphite composite material of the present invention has a high specific surface area and a porous structure thereof, and the liquid absorbing capability of the material is improved.
TABLE 4
| Negative electrode material for battery | Capacity retention (%) after 500 cycles |
| Example 1 | 95.62 |
| Example 2 | 94.78 |
| Example 3 | 94.39 |
| Comparative example 1 | 87.11 |
| Comparative example 2 | 90.55 |
The table 4 shows that the cycle performance of the battery in the example is obviously better than that of the comparative example because the graphite composite material obtained in the example has low expansion rate, so that the consumption of electrolyte is reduced in the cycle process, the side reaction is reduced, and the cycle performance is improved; meanwhile, the graphite composite material of the embodiment has a large specific surface area, and the liquid absorption and retention capacity of the material is improved, so that the cycle performance of the material is improved.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in any way, and any simple modification, equivalent change and modification made to the above embodiment according to the technical spirit of the present invention are within the scope of the present invention without departing from the technical spirit of the present invention.
Claims (4)
1. A preparation method of a high-energy-density quick-charging graphite composite material comprises the following steps:
(1) mixing graphite and 1-10 wt% of aqueous alkali at normal temperature, stirring and reacting for 12h, centrifuging the product, vacuum drying at 80 ℃ for 6h and carbonizing at 800 ℃ for 3h, grinding and crushing to obtain porous graphite, adding the porous graphite into 1-10 wt% of inorganic silicon solution, and adding a silane coupling agent, wherein the weight ratio of porous graphite: inorganic silicon: the mass ratio of the silane coupling agent is 90-95: 5-10: 1-5, spray drying, and carbonizing at 700-1000 ℃ for 1-6 h in an inert atmosphere to obtain a silicon-doped graphite complex;
(2) dispersing the silicon-doped graphite complex in an organic solution to prepare a solution with the mass concentration of 1-10%, uniformly stirring, dropwise adding a solution of aluminum nitrate nonahydrate, wherein the silicon-doped graphite complex comprises the following components in percentage by mass: the mass ratio of the aluminum nitrate nonahydrate is 100: 10-30; and then, dropwise adding organic base to adjust the pH value to 5-8, reacting at room temperature for 1-12 h to form aluminum sol, heating to 50-100 ℃, carrying out aging reaction for 6-24 h to form aluminum gel, carrying out vacuum drying and ball milling, placing the obtained aluminum hydroxide coated graphite precursor in a vacuum tube furnace, heating to 700-1000 ℃ under the nitrogen atmosphere, wherein the heating rate is 1-5 ℃/min, and the heat preservation time is 1-6 h, so as to obtain the aluminum oxide/amorphous carbon coated graphite composite material, namely the high-energy-density quick-charging graphite composite material.
2. The process for preparing a high energy density, fast-charging graphite composite material according to claim 1, wherein: the inorganic silicon solution in the step (1) is one of potassium silicate solution or sodium silicate solution.
3. The process for preparing a high energy density, fast-charging graphite composite material according to claim 1, wherein: the silane coupling agent in the step (1) is one of a silane coupling agent KH550, a silane coupling agent KH560 or a silane coupling agent KH 570.
4. The process for preparing a high energy density, fast-charging graphite composite material according to claim 1, wherein: in the step (2), the organic solvent is one of cyclohexane, N-methyl pyrrolidone or carbon tetrachloride.
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Denomination of invention: A high-energy density fast charging graphite composite material and its preparation method Effective date of registration: 20231122 Granted publication date: 20220909 Pledgee: Guiyang Branch of Shanghai Pudong Development Bank Co.,Ltd. Pledgor: Huiyang (Guizhou) new energy materials Co.,Ltd. Registration number: Y2023520000068 |