Preparation method of positive electrode material LiFePO4/C of lithium ion battery

Abstract

The invention discloses a method for preparing the positive electrode material LiFePO4 / C of a lithium ion battery by adopting carbon sources of the polystyrene sphere series. A carbon thermal reduction and solid phase sintering method is adopted in the preparation process. The method comprises the following concrete steps: firstly, uniformly mixing a lithium source, an iron source and a phosphorus source, and then, mixing the mixture with a carbon source; then, adding a solvent for ball milling, and drying to obtain a precursor; and pretreating and calcining the precursor in the protective atmosphere, and then, cooling the precursor in a furnace to synthesize the LiFePO4 / C of which the particle size distribution is uniform and the particle diameter is 200-500nm. The invention has the advantages of wide sources of raw materials, simple preparation method, convenient control and operation, good carbon coating effect, excellent electrochemical performance and the like.

Description

technical field [0001] The present invention relates to the preparation method of lithium-ion battery cathode material, especially the lithium-ion battery cathode material LiFePO 4 / C preparation method. Background technique [0002] Cathode materials are an important part of lithium-ion batteries, and the development of new cathode materials has become one of the keys to the development of lithium-ion batteries. Olivine structure LiFePO 4 It has the advantages of low cost, environmental friendliness, high capacity, good safety performance, stable cycle, and stable discharge voltage. However, LiFePO 4 There are also two major defects: one is low electrical conductivity, and the other is low ion diffusion coefficient, which leads to poor high-rate discharge and low-temperature performance of the material. To overcome this shortcoming, technologies such as carbon coating, particle size reduction and ion doping are often used to improve. [0003] Currently, LiFePO 4 The m...

AI Technical Summary

Problems solved by technology

However, LiFePO 4 There are also two major defects: one is low electrical conductivity, and the other is low ion diffusion coefficient, resulting in poor high-rate discharge and low-temperature performance of the material

Although this method is easy to synthesize LiFePO 4 / C, but there are also large defects: if the sintering temperature is low, LiFePO 4 The crystallinity is not high, which affects the electrochemical performance of the material; if the reaction and sintering temperature is to be increased, the product particles will be coarse and the particle size distribution will be uneven; and amorphous carbon often cannot be completely coated on LiFePO 4 particle surface

[0005] Although the solid-state reaction method is simple, the prepared LiFePO 4 Coarse particles are prone to occur, and the particle size distribution range is also wide. In the process of carbothermal reduction reaction with traditional carbon sources such as graphite, glucose, sucrose, etc., due to the small contact area between particles, the carbon source during high temperature pyrolysis Poor fluidity, unable to ensure uniform and complete coverage of LiFePO with conductive carbon layer 4 Particles, which affect the high-current discharge and cycle performance of the material