The priority leaching of lithium from spent LiFePO4 cathode without the oxidization

Abstract

Due to the scarcity of Li resources and the environmental burden, comprehensive and efficient recycling of spent LiFePO4 batteries has attracted extensive attention. The existing recycling strategy still has obstacles of low Li recovery efficiency and high consumption of acid and base. The pressure leaching was proposed to extract Li from the spent LiFePO4 cathode selectively without oxidization. The process is mainly to fix the Fe and P in the residue and the Li into the water phase, reducing the reagent consumption and the burden of subsequent removal of Fe and P. More than 99 % of Li could be extracted into the solution under optimal conditions, and it avoided the entrance of the impurities Al and Ca into the leaching solution. The extraction mechanism indicated that the selective extraction of Li and the precipitation of Fe3(PO4)2‧8H2O were carried out stepwise. In addition, the leaching solution was used to prepare high-purity Li2CO3 products and leaching residue could be applied to produce battery-grade FePO4. This process puts forward a new approach to recovering Li from spent LiFePO4 batteries, which has the advantages of high efficiency, reagent cost savings, and easy operation.