Preparation method of high-performance ferrous phosphate

Abstract

The invention discloses a preparation method of high-performance battery-grade ferrous phosphate. The method comprises the following steps: preparing a mixed solution of an iron source and a metal ionadditive, wherein ferrous sulfate with a concentration of 0.5-2 mol / L and a metal ion additive are mixed to prepare an iron source aqueous solution, and the molar ratio of the metal ions in the metaladditive to the iron is (0.05-0.1):1; and preparing a mixed solution of a phosphorus source, a complexing agent and a surfactant, wherein a phosphorus source, a complexing agent and a surfactant aremixed according to a certain ratio to prepare a phosphorus source aqueous solution, a molar ratio of phosphorus to iron is (0.7-0.8):1, concentrate molar ratio of the complexing agent to iron is (0.01-0.1):1, and a mass ratio of the surfactant to iron is (0.5-3%):1. According to the invention, the basic electrical property of a LiFePO4 positive electrode material can be improved, a LiFePO4 positive electrode material precursor ferrous phosphate is modified, and a mesoporous metal ion doped ferrous phosphate material is prepared by optimizing a ferrous phosphate synthesis process.

Description

technical field [0001] The invention relates to the technical field of preparation of electrochemical power source materials, in particular to a preparation method of high-performance ferrous phosphate. Background technique [0002] Among the developed lithium-ion cathode materials, lithium iron phosphate has become the most popular choice due to its environmental friendliness, low raw material cost, high theoretical capacity (170mAh / g), stable voltage platform, excellent safety performance, good thermal stability, and excellent cycle performance. The research hotspot of the new generation of positive electrode materials, but lithium iron phosphate has two obvious defects, one is poor conductivity, high rate charge and discharge efficiency is low; the other is low tap density, resulting in low volume specific capacity, these two defects affect its material In practical applications, especially the poor consistency of the production process, people currently use metal nanopar...

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Problems solved by technology

[0002] Among the developed lithium-ion cathode materials, lithium iron phosphate has become the most popular choice due to its environmental friendliness, low raw material cost, high theoretical capacity (170mAh / g), stable voltage platform, excellent safety performance, good thermal stability, and excellent cycle performance. The research hotspot of the new generation of positive electrode materials, but lithium iron phosphate has two obvious defects, one is poor conductivity, high rate charge and discharge efficiency is low; the other is low tap density, resulting in low volume specific capacity, these two defects affect its material In practical applications, especially the poor consistency of the production process, people currently use metal nanoparticle coating, carbon coating and ion doping to improve the conductivity of materials, and carbon coating can only improve the conductivity of materials to a limited extent. The increase of the material leads to a decrease in the tap density of the material, only 0.7-1.0g / cm 3 , although metal nanoparticle coating and ion doping effects can greatly improve the conductivity of the material, since the metal particle and ion doping process is a solid-solid mixture, the material cannot be fully coated and uniformly doped.