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

A technology of silicon-carbon composite materials and carbon-based composite materials, applied in battery electrodes, secondary batteries, circuits, etc., can solve problems such as difficult large-scale production, complex synthesis process, time-consuming and laborious, etc.

Active Publication Date: 2016-12-28
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 methods, 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, lithium-ion battery

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Embodiment 1

[0025] This embodiment provides a method for preparing a silicon-carbon composite material, comprising the following steps:

[0026] (1) Forming silica on the simple carbon-based material to obtain a silica-carbon-based composite material;

[0027] (2) Reducing the silicon dioxide in the silicon dioxide-carbon-based composite material to silicon with a metal more active than silicon to obtain a metal oxide-silicon-carbon-based composite material;

[0028] (3) Corroding the metal oxide in the metal oxide-silicon-carbon-based composite material with acid to obtain a silicon-carbon composite material.

[0029] In this example, a silicon-carbon composite material was prepared by the above-mentioned method.

[0030] This embodiment also provides a lithium-ion battery, the negative electrode of which contains the above-mentioned silicon-carbon composite material.

[0031] The preparation method of the silicon-carbon composite material in this example firstly forms silicon dioxide ...

Embodiment 2

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

[0034] (1) Add expanded graphite (with a particle size of 1000 mesh) into ethanol, and then add a catalyst, which is a 10% ammonia solution. After ultrasonic dispersion is uniform, add tetraethyl orthosilicate while stirring. Tetraethyl orthosilicate undergoes a hydrolysis reaction to generate silicon dioxide in the microscopic pores of the expanded graphite. After stirring for 24 hours, it is filtered, washed with water, and dried to obtain a silicon dioxide-expanded graphite composite material.

[0035] (2) Weigh calcium particles (particle size 1mm), wherein the amount of calcium particles is 50% of the theoretical amount that can completely reduce the silicon dioxide in step (1). Mix calcium particles with the silica-expanded graphite composite material obtained in step (1), add toluene to it, then add steel balls, put them into a planetary ball mil...

Embodiment 3

[0046] This embodiment provides a method for preparing a silicon-carbon composite material, comprising the following steps:

[0047] (1) Add acetylene black, a simple silicon-based material, to ethanol, and then add a catalyst. The catalyst is a hydrochloric acid solution with a concentration of 10%. After ultrasonic dispersion is uniform, tetrapropyl orthosilicate is added while stirring. The hydrolysis reaction of tetrapropyl ester produces silicon dioxide in the microscopic pores of acetylene black. After stirring for 12 hours, it is filtered, washed with water, and dried to obtain a silicon dioxide-acetylene black composite material.

[0048] (2) Weigh sodium particles (particle size 1mm), wherein the amount of sodium particles is 80% of the theoretical amount that can completely reduce the silicon dioxide in step (1). Mix the sodium particles with the silica-acetylene black composite material obtained in step (1), add ether to it, add steel balls, put them into a planetar...

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Abstract

The invention discloses a silicon-carbon composite material and a preparation method thereof as well as a lithium ion battery. The method comprises the following steps of: (1) forming silicon dioxide on elemental carbon-based material to obtain silicon dioxide-carbon-based composite material; (2) reducing the silicon dioxide in the silicon dioxide-carbon-based composite material into silicon by metal with activity larger than that of the silicon to obtain metallic oxide-silicon-carbon-based composite material; (3) corroding the metallic oxide in the metallic oxide-silicon-carbon-based composite material by acid to obtain the silicon-carbon composite material. According to the method, the silicon dioxide is firstly formed on the carbon-based material, and a gap is formed between the carbon-based material and the silicon after the silicon dioxide is reduced into the silicon; the carbon-based material is good conducting material, thus becoming a conductive frame of the silicon. Therefore, when lithium is embedded into the lithium ion battery made from the silicon-carbon composite material, the increased volume can be contained in the gap between the carbon-based material and the silicon, so that the damage to a pole piece caused by the volume effect can be alleviated.

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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Patent Type & Authority Patents(China)
IPC IPC(8): H01M4/38H01M10/0525
CPCY02E60/10
Inventor 曾绍忠赵志刚阴山慧王秀田胡德言陈效华
Owner CHERY AUTOMOBILE CO LTD