Method for regenerating positive active material from waste lithium iron phosphate batteries

Abstract

The invention discloses a method for regenerating a positive active material from waste lithium iron phosphate batteries. The method comprises the steps as follows: 1) waste lithium iron phosphate batteries are discharged in saline water, and organic solvents, roll cores and casing materials are disassembled; 2) the roll cores are subjected to crushing, calcination and other steps, and active materials, copper foil and aluminum foil are separated through vibrating screening. Fluorine-containing waste gas is absorbed with lime water, the copper foil and the aluminum foil are separated with a magnetic separation method, the active materials are leached out with sulfuric acid, and a leachate and carbon residues are obtained through separation; 3) Cu<2+> in the leachate is reduced to elementary copper by adding iron powder, meanwhile, Fe<3+> is reduced to Fe<2+>, copper and excessive iron residues are filtered out, aluminum is removed through precipitation with an alkaline liquid, the filtrate is supplemented with a phosphorus source after filtration, the pH value is adjusted by adding the alkaline liquid, coarse lithium iron phosphate precipitates are produced, and finally, battery-grade lithium iron phosphate is obtained through sintering. Comprehensive utilization of the waste lithium iron phosphate batteries and regeneration of the active materials are realized with a simple, practical, economical and feasible method, no secondary pollution is produced, and the method is suitable for industrial production.

Description

technical field [0001] The invention belongs to the field of recycling lithium ion secondary batteries, in particular to a method for regenerating positive active materials from waste lithium iron phosphate batteries. Background technique [0002] With the rapid development of modern science and technology, the problem of social energy and environmental ecological pollution has become increasingly prominent, and the environmental and ecological pollution of various waste batteries has become the focus of social attention. Lithium iron phosphate batteries are widely used in power batteries and energy storage batteries due to their low cost, good cycle performance, and good safety performance. However, power and energy storage batteries usually require more battery materials than conventional small batteries. Therefore, in the next 3 to 5 years, a large number of lithium iron phosphate batteries will be scrapped, and their recycling has high social value. [0003] However, at...

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Problems solved by technology

[0010] In order to solve the problems of existing recovered lithium iron phosphate materials such as many heterophases, poor phase uniformity, complicated recovery process, and low recovery rate of the target product, the present invention provides a method for regenerating the positive electrode active material of lithium iron phosphate batteries, aiming at Regeneration of battery-grade lithium iron phosphate in one step

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