Preparation method of lithium iron phosphate/carbon nanotube composite material

Abstract

The invention provides a preparation method of a lithium iron phosphate / carbon nanotube composite material. The preparation method comprises the steps of: dissolving a lithium source and a phosphate source in a mixed liquor agent prepared from alcohol and water to prepare a reaction solution, then adding a ferrous source and a reducing agent, then adding a surfactant, finally adding carbon nanotubes, reacting for 6-8h in a polytetrafluoroethylene high-pressure reaction kettle at 160-200 DEG C to obtain a precursor, calcining the obtained precursor at 600-800 DEG C under the protection of inert gas to prepare the lithium iron phosphate / carbon nanotube composite material with favorable performance. The lithium iron phosphate prepared according to the invention has the advantages of high purity, small grain size, regular shapes and the like, and the carbon nanotubes are embedded into the interiors or cladded onto the surfaces of lithium iron phosphate particles to play a role of electric conductive network, so that the composite material achieves an excellent electrochemical property and is an ideal cathode material for preparing the lithium ion battery.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and relates to a preparation method of lithium iron phosphate / carbon nanotubes, a positive electrode material of lithium ion batteries. Background technique [0002] In the past two decades, due to the high specific capacity and good safety performance of lithium-ion batteries, a technological revolution in portable electronic products has been set off. As the new energy vehicle industry has become one of the country's seven strategic emerging industries, batteries, as the source of power, have become a key bottleneck in the development of the new energy vehicle industry. The rapid development of lithium-ion batteries provides technical support for solving this bottleneck. At the same time, lithium-ion batteries are also the most effective way to store and use sustainable new energy. At present, the common cathode materials for lithium-ion batteries mostly use LiCoO 2 , LiNi 0.8...

AI Technical Summary

Problems solved by technology

Olivine LiFePO 4 There are three main problems in positive electrode materials: low electrical conductivity, low diffusion coefficient of lithium ions, and low tap density

Existing nanoscale LiFePO 4 There are mainly two kinds of preparation methods: hydrothermal method and solvothermal method. Although the particle size of the prepared granular material can reach the nanometer level, its shape is irregular and the size distribution is not uniform, which cannot effectively solve the lithium ion diffusion coefficient. The problem of low and low tap density, its conductivity is still relatively low

Moreover, when preparing nano-sized LiFePO4 by hydrothermal method or solvothermal method, there is no mechanical protective film on the surface of the particles during the growth process of the particles, which cannot prevent the further aggregation of the particles, resulting in clusters.

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