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Silicon-carbon composite material, and preparation method and application thereof

A technology of silicon-carbon composite materials and mixtures, applied in active material electrodes, electrical components, electrochemical generators, etc., can solve the problems of reduced Coulombic efficiency and difficulty in meeting commercial needs

Pending Publication Date: 2021-04-13
CHINA PETROLEUM & CHEM CORP +1
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  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, although the composite material has improved cycle stability, the first coulombic efficiency is significantly reduced, only about 61.9%; patent CN103996837A also discloses a method for preparing a silicon-carbon composite material, which uses a sol-gel method to Using ethyl acetate as the silicon source, a layer of SiOx was deposited on the surface of Si powder, and a layer of carbon was coated on the surface of SiOx@Si, and finally SiOx@Si / C silicon-carbon composite negative electrode material was obtained.
The composite material shows good electrochemical performance, but its first Coulombic efficiency is only 73.8%, which is still difficult to meet the needs of commercialization

Method used

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  • Silicon-carbon composite material, and preparation method and application thereof
  • Silicon-carbon composite material, and preparation method and application thereof
  • Silicon-carbon composite material, and preparation method and application thereof

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preparation example Construction

[0036] One aspect of the present invention provides a method for preparing a silicon-carbon composite material, comprising the following steps: uniformly mixing silicon oxide, silicon, an organic carbon source and graphite to obtain a mixture, stirring the mixture in water to obtain a suspension; The precursor is obtained after crushing and drying; the precursor is roasted to obtain a silicon-carbon composite material.

[0037] According to the present invention, silicon oxide (SiO) has good cycle stability as the lithium ion battery negative electrode material, but its first coulombic efficiency is relatively low; Silicon (Si) has better first coulombic efficiency and higher coulombic efficiency as the negative electrode material. Theoretical specific capacity, but its cycle stability is relatively poor. Although the existing methods have been reported to prepare silicon-carbon composite materials by combining the two with carbon sources, none of them can solve the problem of...

Embodiment 1

[0058] (1) Disperse 2g of glucose and 2g of PVP in 150ml of deionized water, add 2g of nano silicon powder (50-150nm) and 2g of SiO (2-5μm) into the above solution, stir at 500rpm for 3h, then add 0.5 g sodium carboxymethyl cellulose (CMC) and 16g of graphite flakes (3500 mesh, Xianfeng Nano) with a particle size of 5 to 10 μm, then added 1.29g of CNTs (accounting for 5% of the total mass), and continued to stir for 0.5h to obtain suspension;

[0059] (2) Transfer the suspension obtained in step (1) to a 500mL stainless steel ball mill tank, add stainless steel balls at a ratio of 10:1 by the ball-to-material ratio, and feed Ar gas into the ball mill tank. The rotating speed ball mill is 8h. The suspension after ball milling was sand milled at a speed of 2200rpm for 0.5h in a sand mill;

[0060] (3) The slurry after sanding in step (2) was granulated by spray drying, the inlet temperature during spray drying was 180°C, and the outlet temperature was 100°C. Obtain silicon-ca...

Embodiment 2

[0064](1) Disperse 2g of glucose and 2g of PVP in 150ml of deionized water, add 2g of nano silicon powder (50-150nm) and 2g of SiO (2-5μm) into the above solution, stir at 500rpm for 3h, then add 0.5 g sodium carboxymethyl cellulose (CMC) and 16g of graphite flakes (3500 mesh, Xianfeng Nano) with a particle size of 5 to 10 μm, then added 1.29g of CNTs (accounting for 5% of the total mass), and continued to stir for 0.5h to obtain suspension;

[0065] (2) Transfer the suspension obtained in step (1) to a 500mL stainless steel ball mill tank, add stainless steel balls at a ratio of 10:1 by the ball-to-material ratio, and feed Ar gas into the ball mill tank. The rotating speed ball mill is 8h. The suspension after ball milling was sand milled at a speed of 2200rpm for 0.5h in a sand mill;

[0066] (3) The slurry after sanding in step (2) was granulated by spray drying, the inlet temperature during spray drying was 180°C, and the outlet temperature was 100°C. Obtain silicon car...

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Abstract

The invention provides a silicon-carbon composite material, and a preparation method and application thereof. The method comprises the following step: evenly mixing silicon monoxide, silicon, an organic carbon source and graphite to obtain a mixture, placing the mixture in water, and stirring to obtain a suspension; crushing the suspension, and drying to obtain a precursor; and roasting the precursor to obtain the silicon-carbon composite material. According to the method, graphite is used as a carbon source, silicon monoxide and silicon are used as double silicon sources, the advantages of the graphite and the silicon monoxide are combined, the cycling stability of the silicon-carbon composite material is effectively improved, in addition, an organic carbon source is added for compounding, the first coulombic efficiency is improved while the high specific capacity is guaranteed, and the silicon-carbon composite material has excellent comprehensive performance. The preparation method is low in raw material cost, simple in process and easy for industrial production, and has a good application prospect when being used as a lithium ion battery negative electrode material.

Description

technical field [0001] The invention relates to battery material technology, in particular to a silicon-carbon composite material and its preparation method and application. Background technique [0002] Lithium-ion battery is a common energy storage device, which has been widely used in small portable electronic devices due to its advantages of high energy density, long cycle life, high safety and low pollution, and is gradually used in electric vehicles. The electrode material determines the main electrochemical performance of lithium-ion batteries, and it is imperative to develop new electrode materials with high specific capacity, long cycle life and high rate performance. In lithium-ion battery anode materials, the specific capacity of graphitic carbon materials, which have been widely used commercially, is close to its theoretical specific capacity (372mAh g -1 ), it is difficult to greatly increase the specific capacity. Therefore, the development of a new generatio...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/36H01M4/38H01M4/583H01M10/0525
CPCH01M4/362H01M4/386H01M4/583H01M10/0525H01M2004/027Y02E60/10
Inventor 杨文胜张洪涛陈旭于永利林伟国荣峻峰杜泽学
Owner CHINA PETROLEUM & CHEM CORP
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