Recent advancements in hydrometallurgical recycling technologies of spent lithium-ion battery cathode materials

The rapidly increasing production of lithium-ion batteries (LIBs) and their limited service time increases the number of spent LIBs, eventually causing serious environmental issues and resource wastage. From the perspectives of clean production and the development of the LIB industry, the effective recovery and recycling of spent LIBs require urgent solutions. This study provides an overview of the current hydrometallurgical processes employed in the recycling of spent cathode materials, focusing on the leaching of valuable metals and their postprocessing. In particular, this research reviews the various leaching systems (inorganic acid, organic acid, and ammonia) and the separation of valuable metals, and then, recommendations for subsequent study are offered in an attempt to contribute to the development of highly efficient methods for recycling spent cathode materials. In addition, a range of existing technologies, such as solvent extraction, chemical precipitation, electrochemical deposition, and regeneration, for the postprocessing of leaching solutions are summarized. Finally, the promising technologies, existing challenges and suggestions with respect to the development of effective and environmentally friendly recycling methods for handling spent cathode materials are identified.