Graphite silicon-based composite anode material and preparation method thereof

A negative electrode material and composite material technology, which is applied in the preparation process of graphite silicon-based composite negative electrode materials for lithium-ion batteries, can solve problems such as difficult to avoid nano-silicon agglomeration, achieve high specific surface energy, high initial charge and discharge efficiency, Simple operation effect

Inactive Publication Date: 2015-02-18
南京毕汉特威高分子材料有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, in this method, graphite and nano-silicon are composited by spray drying, and it is difficult to avoid the agglomeration of nano-silicon during the drying and compounding process.

Method used

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  • Graphite silicon-based composite anode material and preparation method thereof
  • Graphite silicon-based composite anode material and preparation method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0050] In the presence of an ethanol dispersion medium, use a grinder to grind silicon, and add maleic acid to the silicon grinding solution to control the pH value of the silicon grinding dispersion to 5.8 and the mass solid content to 13%, and set aside. The average particle size of the silicon particles in the silicon polishing liquid is 150nm.

[0051] Preparation of polymer / nano-silicon composite microsphere emulsion: In a four-port glass reactor equipped with a reflux condenser, a thermometer, and a nitrogen pipe, add 58.8 g of 17% polyvinylpyrrolidone PVP ethanol solution, 20% nano Siliconethanol dispersion 125g, ethanol 193.3g, be warming up to 65 ℃, in system, add dropwise the mixed monomer solution containing benzoyl peroxide initiator (0.85g benzoyl peroxide is dissolved in 60g styrene and 40g propylene Nitrile mixed monomer), the dropping time is 30min, after the dropping is completed, the insulation reaction is carried out for 7h, and the polymer / nano-silicon comp...

Embodiment 2

[0055] Preparation of nano-silicon dispersion liquid: prepared as in Example 1, the average particle diameter of silicon particles in the silicon grinding liquid is 150nm.

[0056] Preparation of polymer / nano-silicon microsphere emulsion: In a four-port glass reactor equipped with a reflux condenser, a thermometer, and a nitrogen vent pipe, add 70.5 g of 17% polyvinyl butyral PVB ethanol solution, 20% 105g of nano silicon ethanol dispersion liquid, isopropanol 180.8g, be warming up to 70 ℃, dropwise add the mixed monomer solution containing benzoyl peroxide and azobisisobutyronitrile mixed initiator (0.57g over Benzoyl oxide and 1.20g of azobisisobutyronitrile are dissolved in a mixed monomer of 70g of styrene and 30g of acrylonitrile), and the time for the dropwise addition is 30min. It is a polymer / nano-silicon composite microsphere emulsion with 26.77% and an average particle diameter of 4220nm.

[0057] Liquid-phase compounding of polymer / nano-silicon composite microspher...

Embodiment 3

[0060] Preparation of nano-silicon dispersion: prepared as in Example 1, the obtained nano-silicon dispersion had a solid content of 20%, and the average particle diameter of silicon particles in the silicon grinding liquid was 180 nm.

[0061]In a four-port glass reactor equipped with a reflux condenser, a thermometer, and a nitrogen duct, add 75 g of ethanol solution of 17% polyvinylpyrrolidone PVP, 123.6 g of 13% nano-silicon ethanol dispersion, and 200 g of isopropanol. Contain the mixed monomer solution of benzoyl peroxide and azobisisobutyronitrile mixed initiator (2.86g benzoyl peroxide and 4.14g azobisisobutyronitrile are dissolved in 60g of α-methylstyrene and 40g of prepared from mixed monomers of methacrylonitrile), the titration time is 30min, the temperature is raised to 70°C, and the heat preservation reaction is carried out for 7h to obtain a polymer / nano-silicon composite microsphere emulsion with a solid content of 28.2% and an average particle diameter of 1100...

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Abstract

The invention relates to a graphite silicon-based composite anode material for a lithium ion battery and a preparation method thereof. The graphite silicon-based composite anode material comprises a nano-silicon cracked carbon composite material, graphite and a carbon material coating layer. The preparation method comprises the following steps: firstly, nano-silicon is obtained by a high-energy wet mechanical milling method; secondly, nano-silicon and a polymer with high carbon residue are compounded by dispersion polymerization so as to form a polymer/nano-silicon composite microsphere emulsion with nano-silicon inlaid in polymeric microspheres; thirdly, the microsphere emulsion and graphite are compounded; and finally, solid-phase coating is carried out by the use of an organic carbon source, and heat treatment is conducted to obtain the graphite silicon-based composite anode material for a lithium ion battery. By the above method, the problem that nano-silicon is liable to agglomeration, especially agglomeration of nano-silicon from a liquid disperse state to a dry state, due to low granularity and high specific surface energy is solved. The anode material has characteristics of high specific capacity (greater than 550mAh/g), high initial charge discharge efficiency (greater than 80%) and high conductivity.

Description

technical field [0001] The invention relates to the field of lithium-ion battery materials, in particular to a preparation process for a graphite-silicon-based composite negative electrode material for lithium-ion batteries. Background technique [0002] Due to its high storage capacity (theoretical specific capacity 4200mAh / g) and abundant resources, silicon materials are considered to be one of the ideal candidates for developing a new generation of lithium-ion battery anode materials with high specific energy and high power density. However, the silicon anode undergoes serious volume expansion and contraction during the lithium intercalation and desorption cycle, resulting in the destruction and pulverization of the material structure, which leads to the decline of the electrode cycle performance, which limits its commercial application. Therefore, suppressing the volume expansion of silicon materials and improving the structural stability of materials is of great signifi...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/36H01M4/38H01M4/62H01M10/0525
CPCH01M4/364H01M4/386H01M4/62H01M10/0525Y02E60/10
Inventor 刘祥汪舟鹭
Owner 南京毕汉特威高分子材料有限公司
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