A method for recovering and preparing a lithium-manganese-iron phosphate positive-electrode material covered with carbon from waste lithium iron phosphate batteries

Abstract

The invention provides a method of recovery and reutilization of waste lithium iron phosphate batteries. The method includes (1) separating positive electrode material mixture from the waste lithium iron phosphate batteries; (2) fully dissolving the positive electrode material mixture with sulfuric acid, performing filtration to obtain a first filtrate, adding ammonia water into the filtrate understirring until the pH value of the system is 1.0-1.9, stirring the mixture, and performing filtration to obtain a second filtrate and iron phosphate precipitate; (3) adding barium hydroxide or bariumnitrate into the second filtrate and performing filtration to obtain a third filtrate; (4) adding the third filtrate, the iron phosphate precipitate, a manganese source, a phosphorus source and a carbon source according to the element ratio of a product to be prepared that is lithium-manganese-iron phosphate LiFe<1-x>Mn<x>PO4 to obtain a solution mixture; and (5) subjecting the solution mixture to ball milling, drying and crushing, pre-sintering a product at a first temperature in an inert atmosphere, and sintering the product at a second temperature to obtain the lithium-manganese-iron phosphate positive-electrode material covered with carbon. Through the method, all elements in the waste lithium iron phosphate batteries are recovered and reutilized.

Description

technical field [0001] The invention relates to the technical field of comprehensive utilization of waste resources, in particular to a method for preparing carbon-coated lithium manganese iron phosphate cathode materials from waste lithium iron phosphate batteries. Background technique [0002] With the development of various electronic products and electric tools, people's demand for batteries is increasing day by day. Lithium-ion batteries have been widely used in civil and military fields due to their high specific energy, long cycle life, and good rate performance. At present, lithium-ion batteries using lithium iron phosphate as the positive electrode material are widely used as power batteries for electric vehicles and other power tools due to their relatively low cost and good safety performance. And more and more. Therefore, the effective recycling and reuse of waste lithium iron phosphate batteries has dual significance of economic value and social benefit. [0...

AI Technical Summary

Problems solved by technology

[0003] In order to recycle waste lithium iron phosphate batteries, most people use pyrometallurgical calcination regeneration and hydrometallurgy to recover valuable metals for positive electrode materials, but the regenerated positive electrode materials obtained by pyrometallurgy contain other impurity elements, which will cause battery performance damage after repeated use. Poor, and the hydrometallurgical method is easy to produce a large amount of lye, the post-processing becomes complicated and the cost is high

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