Preparation method of lithium iron phosphate-lithium vanadium phosphate flaky composite cathode material

Abstract

The invention discloses a preparation method of a lithium iron phosphate-lithium vanadium phosphate flaky composite cathode material. The preparation method comprises the following steps that 1, a vanadium source, an iron source, a phosphorus source, a lithium source and an organic carbon source are dissolved into deionized water according to the molar ratio 2:1:4:4:(3-5) of vanadium atoms to iron atoms to phosphorus atoms to lithium atoms to carbon atoms, a surfactant is added, the pH value is regulated, and stirring is conducted; 2, the mixture is transferred into a high-pressure reaction kettle, protective gas is introduced, reacting is conducted for 10 h to 30 h at the speed of 200 rpm to 1,200 rpm at the temperature of 200 DEG C to 300 DEG C, and after washing, filtering and drying are conducted, grinding is conducted; 3, roasting is conducted in a non-oxidative atmosphere at the temperature of 600 DEG C to 800 DEG C, and then the material is obtained. The lithium iron phosphate-lithium vanadium phosphate flaky composite cathode material synthesized through the method has the excellent electronic conductivity and ionic conductivity and is excellent in electrochemical performance, good and stable in product homogeneity and low in cost.

Description

technical field [0001] The invention relates to a preparation method of lithium iron phosphate-lithium vanadium phosphate, a positive electrode material of a lithium ion battery, in particular to a preparation method of a sheet-shaped composite positive electrode material, lithium iron phosphate-lithium vanadium phosphate. Background technique [0002] The conductivity of lithium iron phosphate is very poor, the capacity decays quickly when discharged at a high current, and the low-temperature performance and rate performance are poor; the metal ions in the crystal structure of lithium vanadium phosphate are far apart, which reduces the mobility of electrons in the material, resulting in The electronic conductivity is low, and the effect of charging and discharging under high current is not ideal. Two traditional phosphate-based positive electrode materials are prepared together, and the high ion conductivity, high theoretical specific capacity and high discharge voltage of l...

AI Technical Summary

Problems solved by technology

[0002] The conductivity of lithium iron phosphate is very poor, the capacity decays quickly when discharged at a high current, and the low-temperature performance and rate performance are poor; the metal ions in the crystal structure of lithium vanadium phosphate are far apart, which reduces the mobility of electrons in the material, resulting in The electronic conductivity is low, and the effect of charging and discharging under high current is not ideal. Two traditional phosphate-based positive electrode materials are prepared together, and the high ion conductivity, high theoretical specific capacity and high discharge voltage of lithium vanadium phosphate are used. It is an effective method to modify lithium iron phosphate-based materials based on advantages such as platform and good low-temperature discharge performance.

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