A novel closed-loop process for the simultaneous recovery of valuable metals and iron from a mixed type of spent lithium-ion batteries

Abstract

It might be of practical significance to recover different metals from the already complicated waste spent lithium-ion battery (LIB) stream by simplified recycling processes. This study is, therefore, focused on the exploration of a simplified process for the simultaneous recovery of different metals from waste cathode materials of mixed types of spent LIBs. It is discovered that the leaching agent phosphoric acid demonstrates natural repulsion for Fe, while valuable metals such as Ni, Co, Mn, and Li can be completely dissolved under optimized leaching conditions, indicating a coupling reaction of selective leaching and precipitating for valuable metals and iron, respectively. Characterization results indicate valuable metal-enriched solution and pure FePO₄ in leaching solution and residue, respectively. Kinetics and dynamics studies suggest that the leaching of valuable metals is co-controlled by chemical reaction and internal diffusion, accompanying a spontaneous formation of FePO₄. Then, new cathode materials LiFePO₄ and LiNi_1/3Co_1/3Mn_1/3O₂ with sound electrochemical performances can be re-fabricated from leaching residues and lixivium, respectively, and phosphoric acid can be regenerated during the co-precipitating of valuable metals. This entire recycling process can be a highly selective, closed-loop and simplified alternative for recycling different metals from the current most complicated waste LIB stream.