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Silicon/carbon composite anode material for lithium ion batteries and preparation method thereof

A negative electrode material and carbon composite technology, applied in the direction of battery electrodes, batteries, negative electrodes, etc., can solve the problems of restricting battery cycle performance and rate performance, shortening lithium ion transmission distance, mechanical pulverization, etc., and achieve good lithium ion transmission performance , Ensure electrochemical stability, reduce the possible effect of agglomeration

Active Publication Date: 2015-07-01
GENERAL RESEARCH INSTITUTE FOR NONFERROUS METALS BEIJNG
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  • Abstract
  • Description
  • Claims
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Problems solved by technology

However, the large volume change of the silicon material during the intercalation / delithiation process will cause the destruction of the material structure and mechanical pulverization. At the same time, the electrical conductivity of the silicon material is relatively poor, which restricts the cycle performance and rate performance of the battery. hindering its industrial application
[0004] Aiming at the problems encountered in the application of silicon anode materials, researchers currently use two methods to improve the properties of silicon anode materials: nano-size of materials and compounding of materials Easy release to prevent particle breakage while shortening lithium ions (Li + ) transmission distance, to speed up the transmission speed; however, pure silicon nanoparticles have high surface energy and defects, their thermodynamic properties are unstable, and they are easy to agglomerate during charge and discharge, resulting in rapid decline in battery capacity

Method used

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  • Silicon/carbon composite anode material for lithium ion batteries and preparation method thereof
  • Silicon/carbon composite anode material for lithium ion batteries and preparation method thereof
  • Silicon/carbon composite anode material for lithium ion batteries and preparation method thereof

Examples

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preparation example Construction

[0047] The preparation process of the silicon / carbon composite structure negative electrode material of the present invention comprises the following specific preparation steps:

[0048] (1) Preparation of carbon-coated silicon-containing materials: take the silicon-containing material SiO with a mass ratio of 0.1 to 4 z 1 and amorphous carbon precursor 2, and 0≤z≤2, the above two materials are dispersed into ethanol, water or a mixed solution of the two through mechanical stirring, wherein the silicon-containing material SiO z It is in the form of powder, and its particle size is less than 3 μm; the above-mentioned dispersion solution is spray-dried or blast-dried; and the product obtained by drying is sintered and carbonized at 180-600 ° C in a protective atmosphere to obtain a carbon-coated Silicon material 3;

[0049] The precursor of amorphous carbon is one or more of glucose, sucrose, starch and phenolic resin, which is mainly used to form a conductive carbon layer on t...

Embodiment 1

[0057] Get 16g of silicon nanoparticles (particle size D50 is 30nm) and 24g of glucose dispersed in 400g of ethanol, mechanically stirred for 0.5h, and then spray-dried to obtain granular powder, the granular powder in a tube vacuum furnace, Argon protection, calcination at 200°C for 0.5h to obtain material A.

[0058] Take 2g of the above-mentioned material A, and disperse it in 2g of liquid vinyl tris(2-methoxyethoxy)silane monomer compound by mechanical stirring, add 10g of ethanol and 0.5g of hydrochloric acid aqueous solution with a pH of 4, and mechanically After stirring for 0.5 h, add 0.1 g of carbon fiber and 8 g of graphite, and mechanically knead for 10 min to obtain paste mixture B.

[0059] Put the above paste mixture B into a vacuum tube furnace, under argon protection, and calcinate at 750°C for 90 minutes to obtain a block composite material C, whose stoichiometric formula can be expressed as 0.083Si0.058AC-0.059SiO 1.5 C 2.1 &0.0118CF-C.

[0060] The above-...

Embodiment 2

[0063] The same process as in Example 1, except that the amount of carbon fiber added was increased from 0.1 g in Example 1 to 0.3 g. The composite materials obtained under this example have a capacity of 768.5mAh / g and 583.7mAh / g before delithiation for the first time, and a Coulombic efficiency of 75.9% for the first time; after 10 cycles, the specific capacity is 629.6mAh / g, and the capacity retention rate is 107.9%.

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Abstract

The invention relates to a silicon / carbon composite anode material for lithium ion batteries and a preparation method thereof. The material is composed of a graphite framework material, a middle buffer layer SiOC material, carbon fiber and a silicon-containing material with the carbon-coated surface, wherein the silicon-containing material with the carbon-coated surface is combined with the graphite framework material through the buffer layer SiOC and carbon fiber. Stoichiometric equation of the composite anode material is aSiOz@dAC-bSiOxCy&cCF-C, wherein a is less than or equal to 0.2 and greater than 0; b is less than or equal to 0.4 and greater than 0; c is less than or equal to 0.1 and greater than 0; d is less than or equal to 0.1 and greater than 0; z is less than or equal to 2 and greater than or equal to 0; x is less than 4 and greater than 0; and y is less than or equal to 20 and greater than 0. In the composite material, the amorphous carbon-coated silicon material is effectively contacted with graphite under the action of SiOC and carbon fiber so as to avoid agglomeration of the silicon material itself and peeling of graphite. According to the invention, charge-discharge specific capacity is adjustable, and electrochemical cyclic stability is high.

Description

technical field [0001] The invention relates to a silicon / carbon composite negative electrode material for lithium ion batteries and a preparation method thereof, in particular to a highly dispersed silicon / carbon composite negative electrode material for lithium ion batteries and a preparation method thereof. Background technique [0002] Due to its performance advantages, lithium-ion batteries have been used in various mobile energy storage, such as laptops, mobile phones and cameras. With the development of lithium-ion batteries, lithium-ion batteries with high specific energy, long life and low cost that can be applied to electric vehicles and large-scale energy storage power stations will become the focus of research. At present, the development and progress of cathode materials, one of the main factors determining battery performance, has laid the foundation for the research and development of high-performance lithium-ion batteries; however, graphite-based commercial a...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/36H01M4/583
CPCH01M4/134H01M4/1395H01M4/362H01M4/386H01M4/62H01M10/0525H01M2004/027H01M2220/20H01M2220/30Y02E60/10
Inventor 卢世刚王建涛王耀黄斌杨娟玉谭翱
Owner GENERAL RESEARCH INSTITUTE FOR NONFERROUS METALS BEIJNG
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