Selective recovery of lithium from spent lithium iron phosphate batteries using oxidation pressure sulfuric acid leaching system

Abstract

Oxidation pressure leaching was proposed to selectively dissolve Li from spent LiFePO4 batteries in a stoichiometric sulfuric acid solution. Using O2 as an oxidant and stoichiometric sulfuric acid as leaching agent, above 97% of Li was leached into the solution, whereas more than 99% of Fe remained in the leaching residue, enabling a relatively low cost for one-step separation of Li and Fe. And then, by adjusting the pH of leachate, above 95% of Li was recovered in the form of the Li3PO4 product through iron removal and chemical precipitation of phosphate.