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Surface-modified silicon-carbon composite material and preparation method and application thereof

A technology of silicon-carbon composite materials and carbon composite materials, applied in the direction of electrical components, electrochemical generators, battery electrodes, etc., can solve the problems of difficult formation of SEI film, affecting battery performance, low electrical conductivity, etc., and achieve optimized heat treatment process , improve the conductivity, the effect of a simple method

Inactive Publication Date: 2019-03-29
ZOTYE INT AUTOMOBILE TRADING CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although nanonization and compounding can improve the cycle performance of silicon-based negative electrodes, it is still a big challenge to realize the simple and large-scale preparation of nano-silicon-based materials.
In addition, unlike graphite anodes, it is difficult for silicon-based anodes to form a stable SEI film. The residual HF in the electrolyte also has a corrosive effect on silicon, so it is necessary to protect the surface of silicon to form an artificial SEI film. In addition, the electrical conductivity of silicon Low, need to introduce conductive agent
[0004] Currently, additives are used in the electrolyte to form the SEI film. Too many additives will affect the performance of the battery, and too few additives will be gradually consumed during use.

Method used

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  • Surface-modified silicon-carbon composite material and preparation method and application thereof
  • Surface-modified silicon-carbon composite material and preparation method and application thereof
  • Surface-modified silicon-carbon composite material and preparation method and application thereof

Examples

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Effect test

Embodiment 1

[0044] A method for preparing a surface-modified silicon-carbon composite material, comprising the following steps:

[0045] 1) Commercial crude silicon was ball milled at 480r / min for 10 hours, then washed with 0.1mol / L hydrochloric acid for 14 hours, then washed with deionized water until neutral, and then heat-treated at 600°C for 4 hours under an argon atmosphere. Silicon is initially crushed and purified to obtain purified crude silicon;

[0046]2) Mix the crude silicon and magnesium powder purified in step 1) uniformly in a molar ratio of 1:2.02, and heat-treat in an argon atmosphere at 600°C for 10 hours to obtain a magnesium-silicon alloy;

[0047] 3) Cool the magnesium-silicon alloy obtained above to room temperature under an argon atmosphere, and then mix it with sodium carbonate evenly. The molar ratio of sodium carbonate to magnesium-silicon alloy is 0.5:1. The mixture is heat-treated in an argon atmosphere at 800°C for 5 hours, and collected product;

[0048] 4)...

Embodiment 2

[0060] A method for preparing a surface-modified silicon-carbon composite material, comprising the following steps:

[0061] 1) Commercial crude silicon was ball-milled at 480r / min for 10 hours, then washed with 0.1mol / L hydrochloric acid for 14 hours, then washed with deionized water until neutral, and then heat-treated at 600°C for 4 hours under an argon atmosphere. Crude silicon is initially pulverized and purified to obtain purified crude silicon;

[0062] 2) Mix the crude silicon and magnesium powder purified in step 1) uniformly in a molar ratio of 1:2.04, and heat-treat in an argon atmosphere at 550° C. for 15 hours to obtain a magnesium-silicon alloy;

[0063] 3) Cool the magnesium-silicon alloy obtained above to room temperature under an argon atmosphere, and then mix it uniformly with magnesium carbonate. The molar ratio of magnesium carbonate to magnesium-silicon alloy is 0.8:1. The mixture is heat-treated in an argon atmosphere at 750°C for 10 hours, and collected ...

Embodiment 3

[0070] A method for preparing a surface-modified silicon-carbon composite material, comprising the following steps:

[0071] 1) The commercial crude silicon was ball milled at 480r / min for 10 hours, then washed with 0.1mol / L hydrochloric acid for 14 hours, neutralized with deionized water, and then heat-treated at 600°C for 4 hours under an argon atmosphere. Perform preliminary crushing and purification to obtain purified crude silicon;

[0072] 2) Mix the crude silicon and magnesium powder purified in step 1) uniformly in a molar ratio of 1:2.06, and heat-treat in an argon atmosphere at 650° C. for 5 hours to obtain a magnesium-silicon alloy;

[0073] 3) Cool the magnesium-silicon alloy obtained above to room temperature under an argon atmosphere, and then mix it uniformly with potassium carbonate. The molar ratio of potassium carbonate to magnesium-silicon alloy is 1:1. The mixture is heat-treated in an argon atmosphere at 750°C for 10 hours, and collected product;

[0074...

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Abstract

The invention discloses a surface-modified silicon-carbon composite material and a preparation method and application thereof. The preparation method comprises the following steps: purifying commercial coarse silicon, enabling the purified commercial coarse silicon to react with magnesium to obtain a magnesium-silicon alloy, carrying out thermal decomposition of the magnesium-silicon alloy to obtain nano-silicon, carrying out in-situ carbon coating to obtain a silicon-carbon nano-material, and compounding the nano-silicon carbon with fluoride through ball milling to obtain a silicon-based composite material. Compared with the prior art, the method provided by the invention is low in energy consumption, low in cost, short in period and beneficial to large-scale production. According to themethod, the volume change of silicon in the lithiation / delithiation process can be buffered, and the contact between silicon particles and the electrolyte can be prevented, so that the silicon is prevented from being corroded by the electrolyte, and the diffusion of lithium ions from the liquid electrolyte to the silicon particles is not influenced. The prepared surface fluoride modified silicon-carbon composite material is high in capacity, is high in initial coulombic efficiency, and is excellent in cycle performance.

Description

technical field [0001] The invention relates to the technical field of energy storage batteries, in particular to a surface-modified silicon-carbon composite material and a preparation method and application thereof. Background technique [0002] Lithium-ion batteries are now widely used in mobile electronic devices, such as smartphones, laptops, etc., and have huge markets in grid energy storage, electric vehicles. However, with the large-scale use of lithium-ion batteries in electric vehicles, traditional graphite-based anodes cannot meet the increasing requirements of high energy density for power batteries. Compared with graphite-based negative electrodes, the theoretical capacity of silicon-based negative electrodes reaches 4200mAh / g, which has important application prospects. [0003] However, in the process of forming the lithium-silicon alloy, the volume expansion is as high as 300%, which seriously affects the cycle life of the material. At present, measures to im...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/36H01M4/38H01M4/62H01M10/0525
CPCH01M4/366H01M4/386H01M4/628H01M10/0525Y02E60/10
Inventor 牛丽媛郑东沈长海刘慧军金源谢健郭永斌
Owner ZOTYE INT AUTOMOBILE TRADING CO LTD
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