CN110707316B - Silicon-based lithium ion battery cathode material and preparation method thereof - Google Patents
Silicon-based lithium ion battery cathode material and preparation method thereof Download PDFInfo
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- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 title claims abstract description 90
- 229910052710 silicon Inorganic materials 0.000 title claims abstract description 90
- 239000010703 silicon Substances 0.000 title claims abstract description 90
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title claims abstract description 54
- 229910001416 lithium ion Inorganic materials 0.000 title claims abstract description 54
- 239000010406 cathode material Substances 0.000 title claims abstract description 21
- 238000002360 preparation method Methods 0.000 title claims abstract description 12
- 229920000642 polymer Polymers 0.000 claims abstract description 64
- 239000002131 composite material Substances 0.000 claims abstract description 63
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 57
- 239000011247 coating layer Substances 0.000 claims abstract description 43
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 40
- 239000002086 nanomaterial Substances 0.000 claims abstract description 35
- 239000008367 deionised water Substances 0.000 claims abstract description 14
- 229910021641 deionized water Inorganic materials 0.000 claims abstract description 14
- 238000000034 method Methods 0.000 claims abstract description 14
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 14
- 239000011230 binding agent Substances 0.000 claims abstract description 11
- 239000007773 negative electrode material Substances 0.000 claims abstract description 11
- 238000001694 spray drying Methods 0.000 claims abstract description 9
- 238000006243 chemical reaction Methods 0.000 claims description 24
- -1 ester compounds Chemical class 0.000 claims description 19
- 239000000203 mixture Substances 0.000 claims description 15
- 239000002245 particle Substances 0.000 claims description 15
- 238000005086 pumping Methods 0.000 claims description 15
- 239000003792 electrolyte Substances 0.000 claims description 13
- 239000007787 solid Substances 0.000 claims description 13
- 239000011259 mixed solution Substances 0.000 claims description 11
- 229910021389 graphene Inorganic materials 0.000 claims description 8
- 229920003229 poly(methyl methacrylate) Polymers 0.000 claims description 8
- 239000004926 polymethyl methacrylate Substances 0.000 claims description 8
- 239000011856 silicon-based particle Substances 0.000 claims description 8
- 238000000227 grinding Methods 0.000 claims description 7
- 238000001035 drying Methods 0.000 claims description 6
- 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 5
- 239000001768 carboxy methyl cellulose Substances 0.000 claims description 5
- 229920001343 polytetrafluoroethylene Polymers 0.000 claims description 5
- 239000004810 polytetrafluoroethylene Substances 0.000 claims description 5
- 235000019812 sodium carboxymethyl cellulose Nutrition 0.000 claims description 5
- 229920001027 sodium carboxymethylcellulose Polymers 0.000 claims description 5
- 239000002904 solvent Substances 0.000 claims description 5
- 239000000853 adhesive Substances 0.000 claims description 4
- 230000001070 adhesive effect Effects 0.000 claims description 4
- 239000011248 coating agent Substances 0.000 claims description 4
- 238000000576 coating method Methods 0.000 claims description 4
- 238000002156 mixing Methods 0.000 claims description 4
- 229920003048 styrene butadiene rubber Polymers 0.000 claims description 4
- UCPYLLCMEDAXFR-UHFFFAOYSA-N triphosgene Chemical compound ClC(Cl)(Cl)OC(=O)OC(Cl)(Cl)Cl UCPYLLCMEDAXFR-UHFFFAOYSA-N 0.000 claims description 4
- 239000002253 acid Substances 0.000 claims description 3
- 239000002134 carbon nanofiber Substances 0.000 claims description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 2
- 239000002048 multi walled nanotube Substances 0.000 claims description 2
- 229910052814 silicon oxide Inorganic materials 0.000 claims description 2
- 239000002109 single walled nanotube Substances 0.000 claims description 2
- 239000010405 anode material Substances 0.000 claims 3
- 150000001242 acetic acid derivatives Chemical class 0.000 claims 1
- 150000004649 carbonic acid derivatives Chemical class 0.000 claims 1
- 150000003891 oxalate salts Chemical class 0.000 claims 1
- 238000005056 compaction Methods 0.000 abstract description 4
- 239000007767 bonding agent Substances 0.000 abstract 1
- 239000002041 carbon nanotube Substances 0.000 description 10
- 229910021393 carbon nanotube Inorganic materials 0.000 description 10
- 238000003756 stirring Methods 0.000 description 10
- 230000000052 comparative effect Effects 0.000 description 8
- 239000002210 silicon-based material Substances 0.000 description 8
- 238000007599 discharging Methods 0.000 description 7
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 6
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 description 6
- 239000000463 material Substances 0.000 description 5
- 239000010410 layer Substances 0.000 description 4
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 description 3
- 238000002679 ablation Methods 0.000 description 3
- 125000005456 glyceride group Chemical group 0.000 description 3
- 238000011065 in-situ storage Methods 0.000 description 3
- 238000011068 loading method Methods 0.000 description 3
- 230000014759 maintenance of location Effects 0.000 description 3
- CYIDZMCFTVVTJO-UHFFFAOYSA-N pyromellityc acid Natural products OC(=O)C1=CC(C(O)=O)=C(C(O)=O)C=C1C(O)=O CYIDZMCFTVVTJO-UHFFFAOYSA-N 0.000 description 3
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- JFMGYULNQJPJCY-UHFFFAOYSA-N 4-(hydroxymethyl)-1,3-dioxolan-2-one Chemical compound OCC1COC(=O)O1 JFMGYULNQJPJCY-UHFFFAOYSA-N 0.000 description 1
- 229910013872 LiPF Inorganic materials 0.000 description 1
- 101150058243 Lipf gene Proteins 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000007853 buffer solution Substances 0.000 description 1
- 239000003575 carbonaceous material Substances 0.000 description 1
- 229920001688 coating polymer Polymers 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000008602 contraction Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 230000010287 polarization Effects 0.000 description 1
- 230000002441 reversible effect Effects 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000012795 verification Methods 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
- H01M4/36—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
-
- 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
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/624—Electric conductive fillers
- H01M4/625—Carbon or graphite
-
- 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
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The invention discloses a silicon-based lithium ion battery cathode material and a preparation method thereof, belonging to the technical field of lithium ion batteries. The silicon-based lithium ion battery cathode material sequentially comprises from inside to outside: silicon-based composite material, carbon nano material/polymer mixed coating layer; wherein the mass ratio of the polymer to the silicon-based composite material is 0.05-0.6: 1, and the mass ratio of the carbon nano material to the silicon-based composite material is 0.001-0.1: 1. The silicon-based composite material is prepared from a silicon-based composite material, a polymer, a carbon nano material, a binder, deionized water and the like by a spray drying load method or a fluidized bed load method. The negative electrode material can effectively release stress generated by volume expansion under extremely high pole piece compaction density, can effectively maintain the integrity of a conductive network and a bonding agent network, and can improve the electrochemical performance of a battery cell.
Description
Technical Field
The invention relates to the technical field of lithium ion batteries, in particular to a silicon-based lithium ion battery cathode material and a preparation method thereof.
Background
As a lithium ion battery cathode, the theoretical capacity of a silicon-based material can reach up to 4200mAh/g, and the silicon-based material has the advantages of low potential, stable and long platform discharge, high safety performance and the like, and is considered to be one of high-energy-density cathode materials with the most commercial application prospect in the market. However, the silica-based material has large volume expansion and contraction in the charging and discharging processes, so that particles are crushed to damage the structure and influence a conductive network to reduce the conductivity, the reversible capacity is rapidly reduced, and the cycle performance is poor.
Chinese patent application CN103474667A, CN102394287A, CN103474667A, CN103367727 and the like compound nanometer silicon-based materials and buffer base materials such as carbon materials and the like in different modes, and then coat the surfaces with carbon layers. From the material level, these methods can play a role in relieving volume expansion and maintaining the completion of the particles. On the pole piece layer, due to the intrinsic volume expansion of the silicon-based material, the high-compaction particles are irreversibly separated due to volume change in the charging and discharging processes, so that the binder network and the conductive network are damaged, the phenomena of pole piece folding, active matter falling and the like are caused, and the cycle performance of the battery cell is seriously influenced.
The Chinese patent CN109830673A is to construct a cavity between the silicon particles and the carbon coating layer to reserve a space for the expansion of the silicon-based material, thereby improving the service life and safety of the material. But due to the existence of the cavity structure, the processing performance and the compaction density of the pole piece of the material are greatly limited, and the capacity and the energy density of the cell are seriously influenced.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention aims to provide a silicon-based lithium ion battery negative electrode material and a preparation method thereof, wherein the negative electrode material can effectively release stress generated by volume expansion under extremely high pole piece compaction density, and can effectively maintain the integrity of a conductive network and a binder network and improve the electrochemical performance of a battery core.
In order to solve the problems, the technical scheme adopted by the invention is as follows:
a silicon-based lithium ion battery cathode material sequentially comprises the following components from inside to outside: silicon-based composite material, carbon nano material/polymer mixed coating layer; wherein the mass ratio of the polymer to the silicon-based composite material is 0.05-0.6: 1, and the mass ratio of the carbon nano material to the silicon-based composite material is 0.001-0.1: 1.
Preferably, the mass ratio of the polymer to the silicon-based composite material is 0.15:1, and the mass ratio of the carbon nano material to the silicon-based composite material is 0.1: 1.
As a preferred embodiment of the invention, the silicon-based composite material is silicon-based particles coated with carbon, and the silicon-based particles are silicon or SiOXOr a mixture of the two, wherein x is more than 0 and less than or equal to 1; the carbon nanomaterial in the carbon nanomaterial/polymer mixed coating layer is one or a mixture of more than two of a single-walled carbon nanotube, a multi-walled carbon nanotube, graphene and carbon nanofiber.
The invention further comprises a polymer coating layer, and the mass ratio of the polymer coating layer to the silicon-based composite material is 0.05-0.4: 1, preferably 0.2: 1.
In a preferred embodiment of the present invention, the polymer in the carbon nanomaterial/polymer mixed coating layer and the polymer coating layer is one or a mixture of two or more of solid olefinic acid ester compounds, solid carbonic acid ester compounds, solid acetic acid ester compounds, solid carboxylic acid ester compounds and solid oxalic acid ester compounds which are soluble in the electrolyte of the lithium ion battery.
Further preferably, the polymers include, but are not limited to: polymethyl methacrylate and derivatives thereof, cyclic glycerol carbonate derivatives, cyclic glycerol sulfite derivatives, triphosgene and derivatives thereof; the particle size of the polymer in the carbon nano material/polymer mixed coating layer and the polymer coating layer is 0.1-1 mu m, and preferably 0.5 mu m.
The invention also comprises a binder, wherein the mass ratio of the binder to the silicon-based composite material is 0.001-0.01: 1, preferably 0.004: 1; the binder is one or a mixture of more than two of polytetrafluoroethylene, styrene butadiene rubber and sodium carboxymethylcellulose.
The invention also provides a preparation method of the silicon-based lithium ion battery cathode material, which comprises the following steps:
uniformly mixing the silicon-based composite material, the polymer, the carbon nano material, the binder and deionized water, pumping the mixture into spray drying equipment at the speed of 0.1g/min-100g/min, wherein the air inlet temperature is 90-300 ℃, taking out after the reaction is finished, grinding and crushing to obtain the silicon-based lithium ion battery cathode material with a silicon-based particle core and a carbon nano material/polymer mixed coating layer shell. Wherein the content of the deionized water is 30-90%.
Further, the above preparation method further comprises the steps of: dissolving a polymer in a solvent of a lithium ion battery electrolyte to ensure that the mass percent of the polymer is 5-20%, preferably 15%; placing the prepared silicon-based lithium ion battery negative electrode material in a fluidized bed; pumping the prepared mixed solution into a fluidized bed for reaction at the speed of 0.1g/min-100g/min, and obtaining the silicon-based lithium ion battery cathode material with the surface coated with the polymer coating layer after the reaction is finished.
The invention also provides another preparation method of the silicon-based lithium ion battery cathode material, which comprises the following steps:
uniformly mixing a polymer, a carbon nano material, a binder and deionized water to prepare a mixed solution; and (3) placing the silicon-based composite material in a fluidized bed, pumping the mixed solution into the fluidized bed for reaction at the speed of 0.1-100 g/min, wherein the air inlet temperature is 90-300 ℃, taking out the silicon-based composite material after the reaction is finished, drying, grinding and crushing the silicon-based composite material to obtain the silicon-based lithium ion battery cathode material with the core of silicon-based particles and the shell of a carbon nano material/polymer mixed coating layer. Wherein the content of the deionized water is 30-90%.
Further, the above preparation method further comprises the steps of: dissolving a polymer in a solvent of a lithium ion battery electrolyte to ensure that the mass percentage of the polymer is 5-20%; placing the prepared silicon-based lithium ion battery negative electrode material in a fluidized bed; pumping the prepared mixed solution into a fluidized bed for reaction at the speed of 0.1g/min-100g/min, and obtaining the silicon-based lithium ion battery cathode material with the surface coated with the polymer coating layer after the reaction is finished.
Compared with the prior art, the invention has the beneficial effects that:
the silicon-based lithium ion battery cathode material disclosed by the invention is characterized in that a coating layer capable of self-melting in situ in lithium ion battery electrolyte, namely a polymer coating layer capable of being dissolved in an electrolyte solvent, is coated on the surface of a silicon-based composite material, and the polymer coating layer occupies a certain volume space in a pole piece made of the cathode material; after the battery core is assembled and is filled with electrolyte, the polymer coating layer is dissolved by the electrolyte, and the occupied area of the polymer coating layer can provide space required by expansion for the silicon-based composite material in the charging and discharging processes, so that the stress generated by volume expansion can be effectively released, and the contact stress with surrounding particles can be relieved; meanwhile, the carbon nano material coated on the surface can still keep physical contact with peripheral particles after the polymer coating is ablated, so that the integrity of the conductive network and the adhesive network is effectively maintained, and the electrochemical performance of the battery cell is improved.
The preparation method of the invention innovatively applies the in-situ self-ablation technology to the field of lithium ion battery cathode materials, provides an expansion space for the silicon-based materials in the battery cell and maintains the integrity of the adhesive network and the conductive network, and has good application prospect in the production aspect of the silicon-based materials.
Detailed Description
The present invention will be described in further detail with reference to specific embodiments.
Example 1: spray drying load method for preparing silicon-based lithium ion battery composite material with silicon-based composite material as core and carbon nano material/polymer mixed coating layer as shell
Adding 500g of silicon-based composite material, 0.5g of polytetrafluoroethylene, 0.5g of carbon nano tube and 25g of polymethyl methacrylate with the particle size of 500nm into 500g of deionized water, uniformly stirring, then carrying out spray drying at the speed of 50g/min, taking out, grinding and crushing, and thus obtaining the silicon-based lithium ion battery composite material with the surface coated with the carbon nano tube and the polymethyl methacrylate.
Example 2: fluidized bed loading method for preparing silicon-based lithium ion battery composite material with silicon-based composite material as core and carbon nano material/polymer mixed coating layer as shell
A. Adding 500g of silicon-based composite material into a cavity of a fluidized bed;
B. adding 5g of a mixture of styrene-butadiene rubber and sodium carboxymethylcellulose, 50g of a mixture of carbon nanotubes and graphene and 200g of bis (2, 3-cyclic carbonate) carbonate with the particle size of 1 mu m into 1000g of deionized water, uniformly stirring, pumping into a fluidized bed at the speed of 80g/min for reaction, wherein the air inlet temperature is 150 ℃, taking out a sample after the reaction is finished, drying and crushing to obtain the silicon-based lithium ion battery composite material with the surface coated with the bis (2, 3-cyclic carbonate) carbonate, the carbon nanotubes and the graphene.
Example 3: spray drying load method for preparing silicon-based lithium ion battery composite material with silicon-based composite material as core, carbon nano material/polymer mixed coating layer as secondary outer layer and polymer coating layer as shell
A. Adding 500g of silicon-based composite material, 0.5g of polytetrafluoroethylene, 1g of carbon nano tube and 30g of polymethyl methacrylate with the particle size of 100nm into 500g of deionized water, uniformly stirring, then carrying out spray drying at the speed of 100g/min, taking out, grinding and crushing to obtain the composite material with the surface coated with the carbon nano tube and the polymethyl methacrylate, wherein the air inlet temperature is 200 ℃;
B. adding the composite material prepared in the step A into a cavity of a fluidized bed;
C. adding 25g of tetra (1, 2-cyclosulfidic acid glyceride) pyromellitic acid ester into 125g of ethylene carbonate, and stirring until the solid is completely dissolved;
D. and D, pumping the tetra (1, 2-cyclosulfidic glyceride) pyromellitic acid ester solution prepared in the step C into a fluidized bed at the speed of 60g/min, and finishing the reaction to obtain the silicon-based lithium ion battery composite material with the surface coated with the tetra (1, 2-cyclosulfidic glyceride) pyromellitic acid ester.
Example 4: fluidized bed loading method for preparing silicon-based lithium ion battery composite material with silicon-based composite material as core, carbon nano material/polymer mixed coating layer as secondary outer layer and polymer coating layer as shell
A. Adding 500g of silicon-based composite material into a cavity of a fluidized bed;
B. adding 40g of a mixture of the carbon nano tube and the graphene and 100g of bis (2, 3-cyclic carbonate glyceride) carbonate with the particle size of 800nm into 800g of deionized water, uniformly stirring, pumping into a fluidized bed at the speed of 10g/min, controlling the air inlet temperature to be 250 ℃, taking out a sample after the reaction is finished, drying and crushing to obtain a composite material with the surface coated with the bis (2, 3-cyclic carbonate glyceride) carbonate, the carbon nano tube and the graphene;
C. b, adding the composite material prepared in the step B into a cavity of a fluidized bed;
D. adding 200g of bis (2, 3-cyclic carbon glyceride) oxalate into 4000g of mixed solution of ethylene carbonate and dimethyl carbonate, and stirring until the solid is completely dissolved;
E. and D, pumping the mixed solution prepared in the step D into a fluidized bed at the speed of 90g/min, and finishing the reaction to obtain the silicon-based lithium ion battery composite material with the surface coated with the bis (2, 3-cyclic glycerol carbonate) oxalate.
Example 5: fluidized bed loading method for preparing silicon-based lithium ion battery composite material with silicon-based composite material as core and carbon nano material/polymer mixed coating layer as shell
A. Adding 500g of silicon-based composite material into a cavity of a fluidized bed;
B. adding 2g of a mixture of sodium carboxymethylcellulose, 50g of graphene and 75g of glycerol cyclosulfite with the particle size of 0.5 mu m into 269g of deionized water, uniformly stirring, pumping into a fluidized bed at the speed of 60g/min for reaction, wherein the air inlet temperature is 300 ℃, taking out a sample after the reaction is finished, drying and crushing to obtain the silicon-based lithium ion battery composite material with the surface coated with the glycerol cyclosulfite and the graphene.
Example 6: spray drying load method for preparing silicon-based lithium ion battery composite material with silicon-based composite material as core and carbon nano material/polymer mixed coating layer as shell, and fluidized bed load method for coating polymer coating layer on surface
A. And adding 500g of the silicon-based composite material, 2g of polytetrafluoroethylene, 50g of the carbon nano tube and 75g of polymethyl methacrylate with the particle size of 500nm into 5643g of deionized water, uniformly stirring, carrying out spray drying at the speed of 100g/min, taking out, grinding and crushing to obtain the silicon-based lithium ion battery composite material with the surface coated with the carbon nano tube and the polymethyl methacrylate, wherein the air inlet temperature is 90 ℃.
B. Adding the composite material prepared in the step A into a cavity of a fluidized bed;
C. adding 100g of triphosgene into 4000g of ethylene carbonate, and stirring until the solid is completely dissolved;
D. and D, pumping the solution prepared in the step C into a fluidized bed at the speed of 90g/min, and finishing the reaction to obtain the silicon-based lithium ion battery composite material with the triphosgene coated on the surface.
Comparative example 1
The silicon-based composite body used in example 1 was used as comparative example 1, which was a sample before improvement.
Comparative example 2:
A. adding 500g of silicon-based composite material into a cavity of a fluidized bed;
B. adding 5g of a mixture of styrene-butadiene rubber and sodium carboxymethylcellulose and 200g of bis (2, 3-cyclic carbonate) carbonate with the particle size of 1 mu m into 1000g of deionized water, uniformly stirring, pumping into a fluidized bed at the speed of 80g/min for reaction, taking out a sample after the reaction is finished, drying and crushing to obtain the silicon-based lithium ion battery composite material with the surface coated with the bis (2, 3-cyclic carbonate) carbonate.
And (3) performance verification:
the silicon-based lithium ion negative electrode materials prepared in the six embodiments and the silicon-based composite materials of comparative examples 1-2 are respectively manufactured into pole pieces and used as working electrodes, and LiPF is used6The button cell is assembled by using/DMC + EC + DEC (1: 1: 1) as electrolyte, the charging and discharging cut-off voltage is 0.01-1.5V, the charging and discharging are carried out by using 100mA/g constant current, the first charging specific capacity, the first coulombic efficiency and the 50-cycle retention rate are measured, and the results are shown in table 1.
TABLE 1 comparison of initial specific charge capacity, initial coulombic efficiency, 50 cycle retention
| Specific capacity for first charge (mAh/g) | First coulombic efficiency (%) | 50-week cycle maintenance (%) | |
| Example 1 | 1346 | 62 | 72 |
| Example 2 | 1684 | 76 | 61 |
| Example 3 | 1342 | 61 | 74 |
| Example 4 | 1668 | 74 | 62 |
| Example 5 | 1670 | 73 | 61 |
| Example 6 | 1668 | 72 | 63 |
| Comparative example 1 | 1345 | 61 | 18 |
| Comparative example 2 | 1664 | 74 | 42 |
As can be seen from table 1, the cycle retention rate of the silicon-based negative electrode material prepared in the six embodiments of the present invention is greatly improved compared with the silicon-based composite material coated with the in-situ self-ablation coating layer in comparative example 1 and compared with comparative example 2 not containing the carbon nanomaterial, which indicates that the polymer coating layer of the present invention is dissolved by the electrolyte after being assembled into the battery cell and the electrolyte is injected into the battery cell, and the occupied area of the polymer coating layer can provide a space required for expansion of the silicon-based composite material during the charging and discharging processes, so as to effectively release the stress generated by volume expansion and alleviate the contact stress with the surrounding particles. The existence of the carbon nano material provides perfect electric contact for the silicon-based material after the ablation of the coating, maintains the integrity of the conductive network and reduces the polarization in the charging and discharging process.
The above embodiments are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited thereby, and any insubstantial changes and substitutions made by those skilled in the art based on the present invention are within the protection scope of the present invention.
Claims (6)
1. The silicon-based lithium ion battery cathode material is characterized in that: comprises the following components in sequence from inside to outside: a silicon-based composite material, a carbon nanomaterial/polymer hybrid coating layer, and a polymer coating layer;
wherein the mass ratio of the polymer in the carbon nano material/polymer mixed coating layer to the silicon-based composite material is 0.05-0.6: 1, and the mass ratio of the carbon nano material in the carbon nano material/polymer mixed coating layer to the silicon-based composite material is 0.001-0.1: 1; the mass ratio of the polymer coating layer to the silicon-based composite material is 0.05-0.4: 1;
the carbon nano material/polymer mixed coating layer and the polymer in the polymer coating layer are one or a mixture of more than two of solid olefine acid ester compounds, solid carbonate compounds, solid acetate compounds, solid carboxylate compounds and solid oxalate compounds which can be dissolved in the lithium ion battery electrolyte.
2. The silicon-based lithium ion battery anode material of claim 1, wherein: the silicon-based composite material is a coatingSilicon-based particles with carbon, the silicon-based particles being silicon or SiOXOr a mixture of the two, wherein x is more than 0 and less than or equal to 1; the carbon nanomaterial in the carbon nanomaterial/polymer mixed coating layer is one or a mixture of more than two of a single-walled carbon nanotube, a multi-walled carbon nanotube, graphene and carbon nanofiber.
3. The silicon-based lithium ion battery anode material of claim 1, wherein: the polymers in the carbon nanomaterial/polymer hybrid coating and the polymer coating include, but are not limited to: polymethyl methacrylate and derivatives thereof, cyclic glycerol carbonate derivatives, cyclic glycerol sulfite derivatives, triphosgene and derivatives thereof.
4. The silicon-based lithium ion battery anode material according to any one of claims 1 to 3, characterized in that: the adhesive is also included, and the mass ratio of the adhesive to the silicon-based composite material is 0.001-0.01: 1; the binder is one or a mixture of more than two of polytetrafluoroethylene, styrene butadiene rubber and sodium carboxymethylcellulose.
5. The preparation method of the silicon-based lithium ion battery negative electrode material as defined in any one of claims 1 to 4, characterized by comprising the following steps: the method comprises the following steps:
uniformly mixing the silicon-based composite material, the polymer, the carbon nano material, the binder and deionized water, pumping the mixture into spray drying equipment at the speed of 0.1g/min-100g/min, taking out after the reaction is finished, grinding and crushing to obtain the silicon-based lithium ion battery cathode material with a silicon-based particle core and a carbon nano material/polymer mixed coating layer shell;
dissolving a polymer in a solvent of a lithium ion battery electrolyte to ensure that the mass percentage of the polymer is 5-20%; placing the prepared silicon-based lithium ion battery negative electrode material in a fluidized bed; pumping the prepared mixed solution into a fluidized bed for reaction at the speed of 0.1g/min-100g/min, and obtaining the silicon-based lithium ion battery cathode material with the surface coated with the polymer coating layer after the reaction is finished.
6. The preparation method of the silicon-based lithium ion battery negative electrode material as defined in any one of claims 1 to 4, characterized by comprising the following steps: the method comprises the following steps:
uniformly mixing a polymer, a carbon nano material, a binder and deionized water to prepare a mixed solution; placing the silicon-based composite material in a fluidized bed, pumping the mixed solution into the fluidized bed at the speed of 0.1g/min-100g/min for reaction, taking out the mixed solution after the reaction is finished, drying, grinding and crushing to obtain a silicon-based lithium ion battery cathode material with a silicon-based particle core and a carbon nano material/polymer mixed coating layer shell;
dissolving a polymer in a solvent of a lithium ion battery electrolyte to ensure that the mass percentage of the polymer is 5-20%; placing the prepared silicon-based lithium ion battery negative electrode material in a fluidized bed; pumping the prepared mixed solution into a fluidized bed for reaction at the speed of 0.1g/min-100g/min, and obtaining the silicon-based lithium ion battery cathode material with the surface coated with the polymer coating layer after the reaction is finished.
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| CN111613796B (en) * | 2020-05-21 | 2022-07-26 | 芜湖天弋能源科技有限公司 | Negative electrode material with negative strain material coated with silicon carbon, preparation method of negative electrode material and lithium ion battery |
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