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Silicon-carbon composite material and preparation method thereof, and lithium ion battery

A silicon-carbon composite material and composite technology, applied in battery electrodes, circuits, electrical components, etc., can solve the problems of complex synthesis process, time-consuming and labor-intensive, difficult to large-scale production, etc., to reduce volume expansion, shorten diffusion path, extend The effect of charge-discharge cycle life

Active Publication Date: 2013-10-09
CHERY AUTOMOBILE CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] The above two methods are very effective in overcoming the specific capacity fading problem of silicon-based negative electrode materials, but due to the very complicated synthesis process adopted by the above method, it is time-consuming and laborious, and it is difficult to produce on a large scale

Method used

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  • Silicon-carbon composite material and preparation method thereof, and lithium ion battery

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Embodiment 1

[0033] This embodiment provides a method for preparing a silicon-carbon composite material, comprising the following steps:

[0034] (1) Add a catalytic amount of concentrated sulfuric acid (generally 0.01-0.15 grams of concentrated sulfuric acid per gram of sucrose) into the sucrose solution, and then add a solution with a specific surface area of ​​700m 2 / g of silica gel (the main component is porous silica), wherein the mass ratio of silica gel to sucrose is 1:1, stir evenly, and evaporate to dryness. Then transfer to a crucible and burn under the protection of nitrogen atmosphere. The burning temperature is 600°C and the burning time is 12 hours to obtain porous carbon-coated silica, thereby forming nano-carbon and silicon dioxide interconnected. composite structure.

[0035] (2) Weigh potassium particles (particle size 1mm), wherein the amount of potassium particles is 100% of the theoretical amount that can completely reduce the silicon dioxide in step (1). Mix the po...

Embodiment 2

[0044] This embodiment provides a method for preparing a silicon-carbon composite material, comprising the following steps:

[0045] (1) Add a catalytic amount of concentrated sulfuric acid (generally 0.01 to 0.15 grams of concentrated sulfuric acid per gram of lactic acid or glucose) into the solution of lactic acid and glucose (where the mass ratio of lactic acid and glucose is 1:1), and then Adding a specific surface area of ​​500m 2 / g of fumed silica powder, wherein the ratio of the mass of fumed silica powder to the sum of the mass of lactic acid and glucose is 2:1, stir evenly, and evaporate to dryness. Transfer to a crucible again, and burn under the protection of a helium atmosphere. The burning temperature is 950 ° C, and the burning time is 0.5 hours, so that porous carbon is coated on the fumed silica, and the carbon in the carbon layer The particle size is nanoscale, and porous carbon-coated fumed silica is obtained.

[0046] (2) Weigh magnesium particles (parti...

Embodiment 3

[0050] This embodiment provides a method for preparing a silicon-carbon composite material, comprising the following steps:

[0051] (1) Add quartz sand with an average particle size of 5 microns to the starch solution, wherein the mass ratio of starch to quartz sand is 4:1, put it into a hydrothermal reaction kettle and heat it to 600°C for 2 hours. Then transferred to the crucible, burning under the protection of argon atmosphere, the burning temperature is 400 ℃, and the burning time is 24 hours, so that the porous carbon is coated on the surface of the quartz sand, and the carbon particles in the carbon layer The diameter is nanoscale, and the porous carbon-coated quartz sand is obtained.

[0052] (2) Weigh lithium and sodium particles (particle size 1mm) (the mass ratio of lithium and sodium is 2:1), wherein the amount of lithium and sodium particles is such that all the quartz sand in step (1) can be reduced 120% of the theoretical usage. Mix the particles of lithium a...

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Abstract

The invention discloses a silicon-carbon composite material and a preparation method thereof, and a lithium ion battery. The method comprises the following steps of (1) coating porous carbon on porous silicon dioxide; (2) reducing the porous silicon dioxide to porous silicon by using a metal more active than silicon to obtain a porous carbon-porous silicon-metal oxide composite; and (3) etching the metal oxide in the carbon-porous silicon-metal oxide composite to obtain the silicon-carbon composite material. In the silicon-carbon composite material, the porous silicon is prepared by a metallothermic method; the porous silicon particles prepared by the metallothermic method are in micron size, so that agglomeration rarely occurs; and pore walls in the porous silicon particles and apertures are in nano size. Compared with imporous micron silicon powder, the silicon-carbon composite material shortens diffusion paths of lithium ions in silicon matrix, thereby facilitating large-current discharge; the holes in the porous silicon particles can accommodate volume expansion in a silicon-embedding process; and charge-discharge cycle life of the material is prolonged.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and in particular relates to a silicon-carbon composite material, a preparation method thereof, and a lithium ion battery. Background technique [0002] At present, the lithium-ion batteries used in production mainly use graphite-based negative electrode materials, but the theoretical lithium intercalation capacity of graphite is 372mAh / g, but it has actually reached 370mAh / g. Therefore, there is almost no room for improvement in the capacity of graphite-based negative electrode materials. [0003] In the past ten years, a variety of new high-capacity and high-rate negative electrode materials have been developed, among which silicon-based materials have become a research hotspot due to their high mass specific capacity (the theoretical specific capacity of silicon is 4200mAh / g). The material is accompanied by serious volume expansion and contraction during the lithium intercalation...

Claims

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Application Information

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IPC IPC(8): H01M4/38H01M4/134
CPCY02E60/10
Inventor 曾绍忠赵志刚陈效华阴山慧
Owner CHERY AUTOMOBILE CO LTD
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