Si-C composite material and preparation method thereof and lithium ion battery containing same

A technology of silicon-carbon composite materials and composite materials, applied in battery electrodes, secondary batteries, circuits, etc., can solve the problems of time-consuming and labor-intensive, difficult large-scale production, etc., achieve high cycle stability, increase stability and conductivity, The effect of alleviating chalking and shedding phenomenon

Active Publication Date: 2013-05-15
CHERY AUTOMOBILE CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The above two methods are very effective in overcoming the specific capacity fading problem of silicon-based negative electrode materials, but because

Method used

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  • Si-C composite material and preparation method thereof and lithium ion battery containing same
  • Si-C composite material and preparation method thereof and lithium ion battery containing same
  • Si-C composite material and preparation method thereof and lithium ion battery containing same

Examples

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Effect test

Embodiment 1

[0035] This embodiment provides a method for preparing a silicon-carbon composite material, comprising the following steps:

[0036] (1) Pre-oxidation

[0037] Weighed 3.0 grams of spherical nano-silicon powder with a particle size of 80 nm, burned it to 400° C. in air for 4 hours, and obtained 4.2 grams of composite material 4 of silicon dioxide coated with silicon in the form of powder. It is measured that the silicon dioxide-coated silicon composite material 4 has a silicon content of 71% and an oxygen content of 29%. Converting the oxygen content therein into the amount of silicon dioxide, it can be known that the silicon dioxide content in the silicon dioxide-coated composite material is 54%.

[0038] (2) Carbon coating

[0039]Weigh 4 grams of the above silicon dioxide-coated silicon composite material 4, add 1 gram of starch and 10 grams of water to it, and ultrasonically disperse for 30 minutes. Then transfer the mixture to a polytetrafluoroethylene reactor, seal th...

Embodiment 2

[0051] This embodiment provides a method for preparing a silicon-carbon composite material, comprising the following steps:

[0052] (1) Pre-oxidation

[0053] Weigh 3.0 grams of spherical nano-silicon powder with a particle size of 100 nm, burn it to 450° C. in air for 2 hours, and obtain 4.3 grams of a composite material of silicon dioxide coated with silicon in the form of powder. It is measured that in the silicon dioxide-coated silicon composite material, the silicon content is 67%, and the oxygen content is 32%. Converting the oxygen content therein into the amount of silicon dioxide, it can be seen that the silicon dioxide content in the silicon dioxide-coated silicon composite material is 60%.

[0054] (2) Carbon coating

[0055] Weigh 4 grams of the above silica-coated silicon composite material, add 2 grams of fructose and 20 grams of water to it, and ultrasonically disperse for 5 minutes. Then transfer the mixture to a polytetrafluoroethylene reactor, seal the po...

Embodiment 3

[0061] This embodiment provides a method for preparing a silicon-carbon composite material, comprising the following steps:

[0062] (1) Pre-oxidation

[0063] Weigh 3.0 g of spherical nano-silicon powder with a particle size of 500 nm, burn it to 600° C. in air for 1 hour, and obtain 4.7 g of a composite material of silicon dioxide coated with silicon in the form of powder. It is measured that in the silicon dioxide-coated silicon composite material, the silicon content is 64%, and the oxygen content is 36%. Converting the oxygen content therein into the amount of silicon dioxide, it can be seen that the silicon dioxide content in the silicon dioxide-coated composite material is 68%.

[0064] (2) Carbon coating

[0065] Weigh 4 g of the above silica-coated silicon composite material, add 4 g of a mixture of sucrose and lactose (wherein the molar ratio of sucrose to lactose is 1:1) and 20 g of water, and ultrasonically disperse for 100 minutes. Then transfer the mixture to ...

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Abstract

The invention discloses a preparation method of a Si-C composite material. The preparation method comprises the following steps of: (1) cauterizing Si powder in an oxygen-containing atmosphere to obtain a SiO2-coated Si composite material; (2) mixing the SiO2-coated Si composite material with a carbohydrate, coating the SiO2-coated Si composite material with a carbon precursor by a hydrothermal method, and heating and carbonizing in an inert atmosphere to obtain a carbon-coated composite material which is coated on the SiO2-coated Si composite material; and (3) corroding SiO2 with excessive hydrofluoric acid to obtain the Si-C composite material. The Si-C composite material provided by the invention has electrochemical reversible lithium embedding/extraction property so as to effectively prevent chalking and dropping of the active particles in the charge/discharge process, and also has high lithium storage capacity property of the Si-based material as well as high cycling stability of the C-based material. Therefore, a battery prepared by the Si-C composite material has better cycling performance.

Description

technical field [0001] The invention belongs to the technical field of battery manufacturing, and in particular relates to a silicon-carbon composite material with high specific capacity, a preparation method thereof, and a lithium-ion battery prepared by using the silicon-carbon composite material. Background technique [0002] At present, the negative electrode of commercialized lithium-ion batteries uses graphitized carbon, such as mesocarbon microspheres MCMB and CMS materials. The volume expansion of these materials is basically below 9% during the lithium intercalation and desorption process, showing high Coulombic efficiency and excellent performance. Cycle stability. However, the theoretical lithium intercalation capacity of graphite is 372mAh / g, and the actual use has reached 370mAh / g. Therefore, the low theoretical lithium storage capacity of the graphite electrode itself makes it difficult to make breakthroughs. Researchers have been exploring a new type Electrod...

Claims

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Application Information

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IPC IPC(8): H01M4/38H01M4/587H01M4/04H01M10/0525
CPCY02E60/122Y02E60/10
Inventor 曾绍忠赵志刚陈效华
Owner CHERY AUTOMOBILE CO LTD
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