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Method for preparing silicon-carbon negative electrode material based on micron silicon dioxide

A technology of silicon dioxide and negative electrode materials, which is applied in the direction of battery electrodes, secondary batteries, electrochemical generators, etc., can solve the problems of high preparation cost, easy aggregation of particles, and difficulty in industrialization and application, and achieve simple operation and low cost Effect

Active Publication Date: 2018-08-31
SICHUAN UNIV +1
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  • Abstract
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  • Claims
  • Application Information

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Problems solved by technology

Yu Xiaolei (Preparation and Performance Research of High-performance Silicon-Carbon Composite Anode Materials for Lithium-ion Batteries, Master Thesis of Shanghai Jiaotong University, 2013) Using two different silicon sources of nano-silica powder and mesoporous silica (SBA-15) , prepared a spherical porous silicon / graphene@carbon (Si / GNS@C) composite material, but the carbon coating method is chemical vapor deposition, which is not easy to be popularized and applied in industrialization; Tao Huachao et al. (prepared by magnesia thermal reduction method Porous silicon-carbon composite anode materials, "Journal of Silicates" 2013 08) based on mesoporous SiO 2 Silicon carbon materials are prepared for the direct magnesia thermal reduction of silicon sources, due to the nanoscale SiO 2 Most of the preparations rely on biomass silicon sources or hydrolysis of tetraethyl orthosilicate (TEOS), and the formed particles are easy to agglomerate, resulting in high preparation costs and unsatisfactory magnesium thermal reaction effects

Method used

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  • Method for preparing silicon-carbon negative electrode material based on micron silicon dioxide
  • Method for preparing silicon-carbon negative electrode material based on micron silicon dioxide
  • Method for preparing silicon-carbon negative electrode material based on micron silicon dioxide

Examples

Experimental program
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Effect test

Embodiment 1

[0023] Weigh SiO 2 30g, 5g of polyvinylpyrrolidone and 120mL of water were placed in a sand mill, wet-milled for 4 hours, separated, placed in a refrigerator, and freeze-dried in a freeze dryer at -45°C for two days and two nights.

[0024] The freeze-dried product was placed in a tube furnace and calcined at 450 °C for 4 h in an inert atmosphere to obtain SiO 2 @C material, then follow SiO 2 The mass ratio of @C:Mg:NaCl is 1:1:1, in an inert atmosphere, magnesia thermal reduction at 650°C for 4 hours, washing in 2M hydrochloric acid solution for 8 hours, to remove magnesia reaction by-products; The solution after washing is added into a hydrofluoric acid solution with a mass fraction of 5% to wash for 0.5h to remove incompletely reacted SiO 2 , washed with deionized water and ethanol solution, filtered until neutral, placed in a vacuum oven, and dried in vacuum at 80°C for 12h to obtain a Si@C composite material.

[0025] The Si@C composite material and graphene oxide wer...

Embodiment 2

[0027] Weigh SiO 2 40g, 10g of polyvinylpyrrolidone and 120mL of water were mixed with a sand mill, wet-milled for 4 hours, separated, placed in a refrigerator, and freeze-dried in a freeze dryer at -45°C for two days and two nights.

[0028] The freeze-dried product was placed in a tube furnace and calcined at 450 °C for 4 h in an inert atmosphere to obtain SiO 2 @C material, then follow SiO 2 The mass ratio of @C:Mg:NaCl is 1:1:1, in an inert atmosphere, magnesia thermal reduction at 650°C for 4 hours, washing in 2M hydrochloric acid solution for 8 hours, to remove magnesia reaction by-products; The solution after washing is added into a hydrofluoric acid solution with a mass fraction of 5% to wash for 0.5h to remove incompletely reacted SiO 2 , washed with deionized water and ethanol solution, filtered until neutral, placed in a vacuum oven, and dried in vacuum at 80°C for 12h to obtain a Si@C composite material.

[0029] The Si@C composite material and graphene oxide w...

Embodiment 3

[0031] Weigh SiO 2 60g, 5g of polyvinylpyrrolidone and 120mL of water were mixed with a sand mill, wet-milled for 4 hours, separated, placed in a refrigerator, and freeze-dried in a freeze dryer at -45°C for two days and two nights.

[0032] The freeze-dried product was placed in a tube furnace and calcined at 500°C for 4 hours in an inert atmosphere to obtain SiO 2 @C material, then follow SiO 2 @C: The mass ratio of Mg:NaCl is 1:1:3, in an inert atmosphere, magnesia thermal reduction at 650°C for 4 hours, washing in 2M hydrochloric acid solution for 8 hours, to remove magnesia thermal reaction by-products; The solution after washing is added into a hydrofluoric acid solution with a mass fraction of 5% to wash for 0.5h to remove incompletely reacted SiO 2 , washed with deionized water and ethanol solution, filtered until neutral, placed in a vacuum oven, and dried in vacuum at 80°C for 12h to obtain a Si@C composite material.

[0033] The Si@C composite material and graph...

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Abstract

A method for preparing a silicon-carbon negative electrode material based on micron silicon dioxide, which comprises the following steps of: 1) preparing a slurry according to the mass ratio of silicon dioxide: carbon source: water=(30-80) : (5-15) : (60-120), wet grinding for 4-5h, freeze-drying to obtain nano-scale silicon dioxide; 2) carbonizing the obtained product of 1) at high temperature toobtain a silicon dioxide-carbon material, and then carrying out magnesium thermal reduction at 600-750 DEG C according to the mass ratio of silicon dioxide-carbon: Mg: NaCl=1:1:1-1:1:10, pickling, washing and drying to obtain the silicon-carbon nanoparticles; 3) ultrasonically mixing the nano particles of 2) with graphene oxide solution, spraying, thermal cracking and coating and reducing to obtain the material. The method has the advantages of low cost, simple operation and uneasy agglomeration, can maintain the original appearance of the sample, has good structural stability of the product,and has strong electrical conductivity and ion transmission capacity of the material.

Description

technical field [0001] The invention belongs to the field of preparation of silicon-carbon negative electrode materials, and in particular relates to a method for preparing silicon-carbon negative electrode materials based on micron silicon dioxide. Background technique [0002] Silicon-based materials are very potential high-performance lithium-ion battery anode materials, with the highest known theoretical specific capacity (4200mAh / g) and low lithium intercalation potential (0.1Vvs.Li / Li+), and abundant resources. Environment friendly. However, the silicon negative electrode is accompanied by a huge volume change (up to 300%) during the process of deintercalating lithium, which will cause the silicon particles to be broken and pulverized, and the electrode material will lose its electrical activity, showing extremely poor cycle stability; in addition, the silicon itself The conductivity is not high and the rate characteristics are poor, which seriously affects the applic...

Claims

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Application Information

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IPC IPC(8): H01M4/36H01M4/38H01M4/62H01M10/0525
CPCH01M4/366H01M4/386H01M4/625H01M4/628H01M10/0525Y02E60/10
Inventor 吴振国吴晨郭孝东向伟钟本和
Owner SICHUAN UNIV
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