High-conductivity lithium iron phosphate powder and preparation method thereof

Abstract

The invention discloses high-conductivity lithium iron phosphate powder and a preparation method thereof. The preparation method comprises the steps as follows: 1) formation of precursor of high-conductivity lithium iron phosphate: a lithium hydroxide solution is stirred and mixed with phosphoric acid; a graphene oxide dispersion liquid is added and stirred; iron sulfate heptahydrate is added and stirred, and a uniform mixture is obtained; the mixture is filtered, washed and dried, and black powder, namely, the precursor of the high-conductivity lithium iron phosphate, is obtained; 2) formation of high-conductivity lithium iron phosphate powder: the precursor, obtained in the step 1), of high-conductivity lithium iron phosphate and lithium carbonate are subjected to ball milling and uniformly mixed, the mixture is calcined in the atmosphere of inert gas, and the high-conductivity lithium iron phosphate powder is obtained. The lithium iron phosphate powder prepared with the method has high conductivity, large specific surface area and higher compaction density, has the particle size of 0.5-1 mu m, has 1-5 layers of graphene and has the iron-phosphorous ratio of 0.95-1.05, and a produced pole piece has the surface resistance of 60 omega and has wide application prospects in the lithium ion battery field.

Description

technical field [0001] The invention belongs to the preparation technology of lithium iron phosphate powder and belongs to the field of inorganic synthesis. Background technique [0002] In the prior art, the preparation of lithium iron phosphate powder mainly adopts a high-temperature solid-phase synthesis method. The basic process of high-temperature solid-state reaction method: After ball milling and mixing iron source, lithium source and phosphorus source, thermal decomposition treatment is carried out at a temperature of 300°C-350°C, and the reactant mixture after thermal decomposition treatment is added to simple organic matter such as glucose, etc. The carbon source is crushed and ball-milled again, and finally a high-temperature solid-state reaction occurs at 600°C-750°C under an inert gas atmosphere such as nitrogen or argon to form lithium iron phosphate with an olivine structure. Although the raw material adaptability of the high-temperature solid-state reaction ...

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Problems solved by technology

However, the high-temperature solid-phase method has a long process, high energy consumption, and high process costs; and the particle size of lithium iron phosphate prepared by the high-temperature solid-phase method is all in the micron level, and the coating layer of amorphous carbon is conductive to the electron conduction of lithium iron phosphate. Sexual improvement is not obvious

[0003] Chinese patent CN102044666B discloses a preparation method of lithium iron phosphate composite material for lithium batteries to solve the problem of insufficient carbon coating or insufficient purity of products in traditional preparation methods

This patent requires the use of high-temperature and high-pressure reactors for the preparation of lithium iron phosphate, which increases the cost of production energy consumption and the complexity of operation, and requires the use of ethanol during washing, which increases the risk

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