Integrating recycled valuable elements from spent LiFePO4 batteries based on a dimethyl oxalate leaching system

Abstract

Recycling of spent lithium-ion batteries (LIBs) has great significance in sustainable global development and environmental protection. In this study, a novel strategy is proposed to selectively separate and integrate valuable elements from spent LiFePO4 (SLFP) cathode materials via an eco-friendly leaching process using dimethyl oxalate. By properly regulating and controlling the leaching parameters, 99.19 % Li and 96.28 % P were leached into solution, whereas only 0.2 % Fe was dissolved. Leaching mechanism revealed that the high-efficiency dissolution of the SLFP cathode materials is due to the joint action of methanol and oxalic acid derived from dimethyl oxalate hydrolysis. Furthermore, the lithium-containing leaching solution was used to prepare Li3PO4 products with a purity of 99.62 % through crystallization, and the Fe was retained in leach residue in the form of FeC2O4·2H2O with a purity of 99.54 %. These findings provide a reliable reference for environmental protection, selective recovery, and process design of SLFP LIBs.