Preparation method of fluorine ion doped lithium iron phosphate material

Abstract

The present invention discloses a preparation method of a fluorine ion doped lithium iron phosphate material. The method comprises the following steps of: S1, preparing of a precursor mixed solution,namely dissolving a soluble lithium source, an iron source, a phosphorus source and fluoride in deionized water, and adding a water-soluble carbon source and a water-soluble auxiliary agent for dissolving to obtain the precursor mixed solution; S2, gelation treatment: carrying out oil bath heating on the precursor mixed solution obtained in the step S1 to obtain viscous precursor gel; S3, self-propagating combustion treatment: heating the precursor gel obtained in the step S2 to carry out self-propagating combustion decomposition to obtain a combustion product; S4, ball-milling treatment: transferring the combustion product obtained by combustion decomposition in the step S3 into a ball-milling tank, and carrying out high-speed ball-milling mixing to obtain mixed slurry; and S5, low-temperature sintering treatment: and cooling the mixed slurry to room temperature to obtain a final product. The preparation method of the fluorine ion doped lithium iron phosphate material has the characteristics of low energy consumption, high tap density, uniform mixing, the good modification effect and the excellent electrochemical performance.

Description

technical field [0001] The invention relates to the technical field of lithium iron phosphate materials, in particular to a method for preparing a fluoride ion-doped lithium iron phosphate material. Background technique [0002] Since J.B.Goodnough [J.Electrochem.Soc., 144 (1997) 1188] research group took the lead in synthesizing olivine-type LiFePO4 in 1997 and using it as the positive electrode material of lithium-ion batteries, LiFePO 4 Because of its stable structure, high specific capacity, long cycle life, low manufacturing cost, good safety performance, and environmental friendliness, it is considered to be an ideal cathode material for lithium-ion power batteries in the future. [0003] However, LiFePO 4 The low electronic conductivity and ion conductivity greatly limit its practical application in the field of lithium-ion power batteries. At present, the main modification methods to improve the conductivity include adding conductive agents, particle size control, ...

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Problems solved by technology

[0005] However, in the actual control process, this method has the following limitations: if the sintering temperature is as high as 450-650°C by the solid-state method, the energy consumption is high, the fluorine ion is seriously lost, and the shape control cannot be performed; such as the way of adding carbon source Both are directly adding solid carbon source to the raw material, which increases the difficulty of mixing and affects the uniformity of mixing

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