Preparation method of lithium iron phosphate cathode material and lithium iron phosphate cathode material

Abstract

The invention discloses a preparation method of a lithium iron phosphate cathode material and the lithium iron phosphate cathode material. The preparation method comprises the steps as follows: lithium iron phosphate is prepared by a solid-phase synthesis method; the solid-phase synthesis method comprises ball-mill mixing and high-temperature calcination; acetylene is introduced into an inert atmosphere during calcination; and carbon nano tubes are formed in generated lithium iron phosphate particles and among the lithium iron phosphate particles to obtain the lithium iron phosphate cathode material with high conductivity. According to the preparation method, a chemical vapor deposition method for the carbon nano tubes is ingeniously combined with the solid-phase synthesis method of the lithium iron phosphate; the carbon nano tubes are gradually deposited on the surfaces of the lithium iron phosphate particles along with synthesis of the lithium iron phosphate during high-temperature calcination; a three-dimensional conductive path is formed in the particles and among the particles; and the conductivity of the cathode material is improved. According to the method, the lithium iron phosphate and the carbon nano tubes are crossly generated in a same reaction container, so that the process is simplified; the carbon nano tubes are evenly distributed; and the quality of the lithium iron phosphate cathode material is improved.

Description

technical field [0001] The present application relates to the field of preparation of positive electrode materials for lithium ion batteries, in particular to a method for preparing a lithium iron phosphate positive electrode material, and the prepared lithium iron phosphate positive electrode material. Background technique [0002] LiFePO 4 It is a positive electrode material widely used in lithium-ion batteries. 1997LiFePO 4 It has been proposed to be used in cathode materials, and has broad application prospects due to its wide source of raw materials, low price, environmental friendliness, stable material structure, good chemical compatibility, and outstanding cycle stability. [0003] However, pure LiFePO 4 There are two obvious shortcomings in the material, one is its low electrical conductivity, which makes it poor in high-rate charge and discharge performance, and it is difficult to adapt to high-current conditions, which is not conducive to the application in pow...

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Problems solved by technology

[0004] In terms of coated carbon, the patent with the publication number CN101546830A discloses a lithium iron phosphate material coated with carbon nanotubes (CNTs). In this method, the carbon nanotubes are directly dispersed into the reactant solution for reaction and coating. The carbon nanotube-coated lithium iron phosphate material has good rate and cycle performance; however, this method directly adds carbon nanotubes to the lithium iron phosphate reactant solution, which is prone to uneven distribution, agglomeration, etc., which affects The quality of lithium iron phosphate material