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CN-121687937-B - Preparation method of double-coated silicon-carbon composite material, electrode and lithium battery

CN121687937BCN 121687937 BCN121687937 BCN 121687937BCN-121687937-B

Abstract

The application belongs to the technical field of lithium batteries, and relates to a preparation method of a double-coated silicon-carbon composite material, an electrode and a lithium battery, wherein the method comprises the steps of soaking a lithium doping agent and an MOF material in a first organic solvent, adding a template agent and a catalyst, reacting, filtering, and freeze-drying to obtain a gel composite; in an inert atmosphere, the gel composite is heated to a first preset temperature, carbon dioxide is introduced according to a preset flow, the temperature is reduced, the gel composite is added into mixed acid for soaking, acid washing and vacuum drying, porous carbon composite material is dried in vacuum, liquid silane, phosphane derivative, dispersing agent, porous carbon composite material and silane coupling agent are added into a second organic solvent, spray drying is carried out, primary carbonization is carried out, silicon carbon precursor material is obtained, resin is dissolved in a third organic solvent, fast ion conductor and silicon carbon precursor material are added, secondary carbonization is carried out, the temperature is reduced to a second preset temperature, reducing gas is introduced, and double-coated silicon carbon composite material is obtained, conductivity is improved, interface stability is improved, and full electric expansion is reduced.

Inventors

  • FU WANQUN
  • FU SHIDI

Assignees

  • 湖南拓森新能源有限公司

Dates

Publication Date
20260508
Application Date
20260209

Claims (10)

  1. 1. The preparation method of the double-coated silicon-carbon composite material is characterized by comprising the following steps: S1, soaking a lithium dopant and an MOF material in a first organic solvent, adding a template agent and an organic catalyst, uniformly mixing, reacting, filtering, and freeze-drying to obtain a gel complex; S2, heating the gel composite to a first preset temperature in an inert atmosphere, introducing carbon dioxide gas according to a preset flow, cooling to an ambient temperature, adding the obtained material into a mixed acid solution for soaking, carrying out acid washing, and then carrying out vacuum drying to obtain a porous carbon composite material; s3, adding liquid silane, phosphane derivatives, a dispersing agent, a porous carbon composite material and a silane coupling agent into a second organic solvent, uniformly mixing, spray-drying, and carbonizing for the first time to obtain a silicon-carbon precursor material; s4, dissolving resin in a third organic solvent, uniformly dispersing, adding a fast ion conductor and a silicon-carbon precursor material, performing secondary carbonization, cooling to a second preset temperature, and introducing reducing gas for reduction treatment to obtain a double-coated silicon-carbon composite material; wherein the template agent is any one of polystyrene microsphere and tetramethyl ammonium hydroxide; The organic catalyst is one or a combination of more of ferrocene, ferrous oxalate, ferric citrate and cupric acetate; the phosphane derivative is any one or a combination of more of (benzoyl methylene) triphenylphosphane, (acetylmethylene) triphenylphosphane and cyanomethylene trimethylphosphane, and P is provided by decomposition of the phosphane derivative, so that P doping is realized, a silicon phosphorus compound is formed, and a buffer phase is formed to play a role in stabilizing a structure; Wherein, the gas yield ratio of the double-coated silicon-carbon composite material is 0.014ml/mg, 0.021ml/mg, 0.032ml/mg, 0.035ml/mg, 0.041ml/mg, 0.043ml/mg, 0.045ml/mg; Wherein the preset flow is 100 ml/min-500 ml/min, the first preset temperature is 900 ℃ to 1100 ℃, and the second preset temperature is 400 ℃ to 600 ℃.
  2. 2. The preparation method of the double-coated silicon-carbon composite material according to claim 1, wherein in the step S1, the mass ratio of the lithium dopant to the MOF material to the first organic solvent to the spherical template to the organic catalyst is (1-5): 100 (500-1000): 5-1): 1-5; the reaction temperature is 100-200 ℃ and the reaction time is 1-6 h; The freeze-drying temperature was-40℃and the time was 24 hours.
  3. 3. The method of preparing a double-coated silicon-carbon composite material according to claim 1, wherein in step S1, the lithium dopant is any one or a combination of a plurality of lithium-rich lithium ferrite, lithium-rich lithium nickelate, lithium-rich manganese base and lithium-rich lithium cobaltate; The MOF material is one or more of ZIF-8, ZIF-67, MOF-74, chromium-based MIL-101, iron-based MIL-101, mg-MOF-74 and Ni-MOF-74; the first organic solvent is any one or a combination of more of dimethyl carbonate, diethyl carbonate, ethylene carbonate and propylene carbonate.
  4. 4. The method for preparing a double-coated silicon-carbon composite material according to claim 1, wherein in the step S2, carbon dioxide gas is introduced for 30 minutes to 300 minutes; the mass ratio of nitric acid to hydrochloric acid in the mixed acid solution is 1:1, and the soaking time is 12 hours.
  5. 5. The preparation method of the double-coated silicon-carbon composite material according to claim 1, wherein in the step S3, the mass ratio of the liquid silane to the phosphane derivative to the dispersant to the porous carbon composite material to the silane coupling agent is 100 (10-30): 1-5): 100-200): 10-20; the primary carbonization temperature is 1000-1300 ℃ and the primary carbonization time is 1-6 hours; In the step S4, the mass ratio of the resin to the third organic solvent to the silicon-carbon precursor material to the fast ion conductor is (2-10): (50-200): (100): (1-5); the temperature of the secondary carbonization is 700-800 ℃ and the time is 1-3 hours; the reduction treatment time is 1-3 h.
  6. 6. The method for preparing a double-coated silicon-carbon composite material according to claim 1, wherein in the step S3, the silane coupling agent is any one or a combination of a plurality of gamma-aminopropyl triethoxysilane, gamma-methacryloxypropyl group, N-beta-aminoethyl-gamma-aminopropyl trimethoxysilane; The dispersing agent is one or a combination of more of polyvinylpyrrolidone, ricinoleic acid, methylcellulose, hydroxypropyl methylcellulose, polyvinyl alcohol and sodium stearate; The liquid silane is one or more of propyl trichlorosilane, dimethyl chlorosilane, trichloroethyl silane, methyl vinyl dichlorosilane, triisopropyl chlorosilane and phenyl dichlorosilane; the second organic solvent is N-methyl pyrrolidone.
  7. 7. The method for preparing a double-coated silicon-carbon composite material according to claim 1, wherein in the step S4, the resin is any one or a combination of a plurality of phenolic resin, furfural resin, epoxy resin and urea-formaldehyde resin; the third organic solvent is any one or a combination of a plurality of xylene, ethyl acetate, acetone and toluene; The fast ion conductor is any one or a combination of a plurality of lithium aluminum titanium phosphate, lithium zirconium phosphate and lithium aluminum silicate; the reducing gas is any one or a combination of more of hydrogen, carbon monoxide and hydrogen sulfide.
  8. 8. The double-coated silicon-carbon composite material is characterized by being prepared by the preparation method of the double-coated silicon-carbon composite material according to any one of claims 1-7.
  9. 9. An electrode, characterized by comprising the double-coated silicon-carbon composite material prepared by the preparation method of the double-coated silicon-carbon composite material according to any one of claims 1 to 7, or the double-coated silicon-carbon composite material according to claim 8.
  10. 10. A lithium battery comprising a positive electrode, a negative electrode, and an electrolyte, wherein the negative electrode is the electrode of claim 9.

Description

Preparation method of double-coated silicon-carbon composite material, electrode and lithium battery Technical Field The application belongs to the technical field of lithium batteries, and particularly relates to a preparation method of a double-coated silicon-carbon composite material, an electrode and a lithium battery. Background The porous carbon is a precursor material of the silicon-carbon composite material, the electronic conductivity or the ionic conductivity of the material is improved mainly by doping hetero atoms, the carbon matrix is a biomass material of resin and coconut shells, the pore volume is small, the expansion is large, the performance of the silicon-carbon composite material is further reduced, and in addition, the current silicon-carbon composite material has high resistivity, and the electrochemical performance of a lithium battery is reduced. The silicon-carbon composite material in the prior art has the problems of small pore volume, large expansion, high resistivity and reduced electrochemical performance of the lithium battery. Disclosure of Invention The application provides a preparation method of a double-coated silicon-carbon composite material, an electrode and a lithium battery, and aims to solve the problems that the silicon-carbon composite material has small pore volume, large expansion and high resistivity and reduces the electrochemical performance of the lithium battery to a certain extent. In a first aspect, the present application provides a method for preparing a double-coated silicon-carbon composite material, comprising: S1, soaking a lithium dopant and an MOF material in a first organic solvent, adding a template agent and an organic catalyst, uniformly mixing, reacting, filtering, and freeze-drying to obtain a gel complex; S2, heating the gel composite to a first preset temperature in an inert atmosphere, introducing carbon dioxide gas according to a preset flow, cooling to an ambient temperature, adding the obtained material into a mixed acid solution for soaking, carrying out acid washing, and then carrying out vacuum drying to obtain a porous carbon composite material; s3, adding liquid silane, phosphane derivatives, a dispersing agent, a porous carbon composite material and a silane coupling agent into a second organic solvent, uniformly mixing, spray-drying, and carbonizing for the first time to obtain a silicon-carbon precursor material; and S4, dissolving resin in a third organic solvent, uniformly dispersing, adding a fast ion conductor and a silicon-carbon precursor material, performing secondary carbonization, cooling to a second preset temperature, and introducing reducing gas for reduction treatment to obtain the double-coated silicon-carbon composite material. In one embodiment, in the step S1, the mass ratio of the lithium dopant to the MOF material to the first organic solvent to the spherical template to the organic catalyst is (1-5) 100 (500-1000) 5-1 (1-5); the reaction temperature is 100-200 ℃ and the reaction time is 1-6 h; The freeze-drying temperature was-40℃and the time was 24 hours. In one embodiment, in step S1, the lithium dopant is any one or a combination of lithium-rich lithium ferrite, lithium-rich lithium nickelate, lithium-rich manganese base, lithium-rich lithium cobaltate; The MOF material is one or more of ZIF-8, ZIF-67, MOF-74, chromium-based MIL-101, iron-based MIL-101, mg-MOF-74 and Ni-MOF-74; The first organic solvent is any one or a combination of more of dimethyl carbonate, diethyl carbonate, ethylene carbonate and propylene carbonate; The template agent is any one of polystyrene microsphere and tetramethyl ammonium hydroxide; the organic catalyst is one or a combination of more of ferrocene, ferrous oxalate, ferric citrate and cupric acetate. In one embodiment, in the step S2, the first preset temperature is 900-1100 ℃, the preset flow is 100-500 ml/min, and the carbon dioxide gas is introduced for 30-300 min; the mass ratio of nitric acid to hydrochloric acid in the mixed acid solution is 1:1, and the soaking time is 12 hours. In one embodiment, in the step S3, the mass ratio of the liquid silane to the phosphane derivative to the dispersing agent to the porous carbon composite material to the silane coupling agent is 100 (10-30)/(1-5)/(100-200)/(10-20); the primary carbonization temperature is 1000-1300 ℃ and the primary carbonization time is 1-6 hours; In the step S4, the mass ratio of the resin to the third organic solvent to the silicon-carbon precursor material to the fast ion conductor is (2-10): (50-200): (100): (1-5); the temperature of the secondary carbonization is 700-800 ℃ and the time is 1-3 hours; the second preset temperature is 400-600 ℃, and the reduction treatment time is 1-3 hours. In one embodiment, in step S3, the silane coupling agent is any one or more of γ -aminopropyl triethoxysilane, γ -methacryloxypropyl, N- β -aminoethyl- γ -aminopropyl trimethoxysilane; The dispersing agent is one or a c