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Preparation method for silicon-carbon composite anode material of lithium ion battery

A lithium-ion battery, silicon-carbon composite technology, applied in the direction of battery electrodes, secondary batteries, circuits, etc., can solve the problems of nano-silicon agglomeration, nano-silicon extraction polymerization reaction, instability, etc., to achieve improved bonding strength, good conductivity and Cushioning effect, effect of improving cycle performance

Inactive Publication Date: 2015-09-16
NANJING UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This method solves the problem that nano-silicon is easy to agglomerate due to its small particle size, high specific surface energy, and exhibits excellent battery performance. However, this method is only suitable for the recombination of a small amount of nano-silicon inside the microsphere and is used in the suspension polymerization process. When excessive nano-silicon is compounded, on the one hand, nano-silicon is easy to escape from the microspheres, making the polymerization reaction unstable; on the other hand, nano-silicon inside the microspheres will agglomerate during high-temperature sintering.

Method used

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  • Preparation method for silicon-carbon composite anode material of lithium ion battery
  • Preparation method for silicon-carbon composite anode material of lithium ion battery

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0053] In the presence of an ethanol dispersion medium, use a ball mill 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 18%, and set aside. The average particle size of the silicon particles in the silicon polishing liquid is 150nm.

[0054] Preparation of polymer / nano-silicon composite microsphere dispersion: Add 58.8 g of 17% polyvinylpyrrolidone ethanol solution, 18% nano Siliconethanol dispersion 111g, ethanol 193.3g, be warming up to 65 ℃, in system, dropwise add the mixed monomer solution containing benzoyl peroxide initiator (5g benzoyl peroxide is dissolved in 60g styrene and 40g acrylonitrile prepared in the 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 composite microsphere dispersion with a solid content of 28.12% and an average particle diamet...

Embodiment 2

[0058] Preparation of nano-silicon dispersion liquid: prepared as in Example 1, the average particle diameter of silicon particles in the silicon grinding liquid is 250nm, and the solid content is 7%.

[0059] The preparation of polymer / nanocomposite silicon microsphere dispersion liquid: in the four port glass reactor that is equipped with reflux condenser, thermometer, nitrogen through pipe, add the ethanol solution 70.5g of 17% polyvinyl butyral PVB successively, 7% nano silicon ethanol dispersion liquid 105g, dehydrated alcohol 180.8g, be warming up to 70 ℃, in system, add dropwise the mixed monomer solution that contains benzoyl peroxide and azobisisobutyronitrile mixed initiator (0.57 g benzoyl peroxide and 1.20 g of azobisisobutyronitrile are dissolved in the mixed monomer of 70 g of styrene and 30 g of acrylonitrile) and the time for the addition is 30 min. The solid content is 26.39%, the average particle size is the polymer / nano-silicon composite microsphere dispersi...

Embodiment 3

[0063] Preparation of nano-silicon dispersion: prepared as in Example 1, the obtained nano-silicon dispersion had a solid content of 9%, and the average particle diameter of silicon particles in the silicon grinding liquid was 220 nm.

[0064] Preparation of polymer / nano-silicon composite microsphere dispersion: In a four-port glass reactor equipped with a reflux condenser, a thermometer, and a nitrogen pipe, add 75 g of 17% polyvinylpyrrolidone PVP ethanol solution, 9% nano Silicon ethanol dispersion 123.6g, ethanol 200g, add the mixed monomer solution containing benzoyl peroxide and azobisisobutyronitrile mixed initiator (2.86g benzoyl peroxide and 3.14g azobisisobutyronitrile are dissolved in 60g of α-methylstyrene and 40g of methacrylonitrile mixed monomer), the titration time is 30min, the temperature is raised to 70°C, and the heat preservation reaction is 7h, and the solid content is 25.36%, and the average particle size is 1200nm polymer / nano-silicon composite microsph...

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Abstract

The present invention relates to a preparation method for a silicon-carbon composite anode material of a lithium ion battery. The method comprises: firstly obtaining nano-silicon dispersion liquid by using a high energy wet mechanical ball milling method; then combining the nano-silicon dispersion liquid with a high-residual-carbon polymer through dispersion polymerization to obtain a polymer / nano-silicon composite micro-sphere dispersion liquid in which flake nano-silicon is embedded in polymer micro-spheres; and finally performing self-assembling, organic carbon sources solid phase coating and heat treatment on the polymer / nano-silicon composite micro-sphere dispersion, the nano-silicon and graphite of the nano-silicon to obtain the silicon-carbon composite anode material of the lithium ion battery. The method solves the problem that nano-silicon is prone to agglomerate as the granularity of the nano-silicon is small and the specific surface energy is high, and adding of elemental silicon greatly improves the capacity of the silicon-carbon composite anode material.

Description

technical field [0001] The invention relates to the field of lithium-ion battery materials, in particular to a preparation process of a silicon-carbon composite negative electrode material for a lithium-ion battery. technical background [0002] Among many alternative negative electrode materials for lithium-ion batteries, silicon has become one of the most potential materials to replace graphite negative electrode materials due to its extremely high specific capacity (theoretical value 4200mAh / g). However, silicon-based negative electrode materials have huge volume changes during the intercalation and deintercalation of lithium ions. If the coating is improper or defective, the electrode active material will be separated from the current collector, which will seriously affect the cycle performance of the battery. This limits its commercial application. Therefore, suppressing the volume expansion of silicon materials and improving the structural stability of materials is of...

Claims

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Application Information

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IPC IPC(8): H01M4/36H01M4/38H01M4/62H01M10/0525
CPCH01M4/366H01M4/38H01M4/625H01M10/0525Y02E60/10
Inventor 刘祥汪舟鹭黄维
Owner NANJING UNIV OF TECH
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