Effective separation and recovery of valuable metals from waste Ni-based batteries: A comprehensive review

The rapidly growing battery industry and the corresponding potential environmental pollution make recycling waste nickel (Ni)-based batteries essential. This review summarized the sources and characteristics of valuable metals in Ni-based batteries. The various treatment processes of waste Ni-based batteries, including acid leaching, bio-leaching, and pyrometallurgy, were compared and discussed. The different pretreatment processes were compared because they influence the recovery of valuable metals. Moreover, the crucial mechanism of hydrometallurgy and pyrometallurgy recovery processes was summarized in detail, and the challenges faced by various pretreatment and recovery processes were also pointed out. A comprehensive treatment method was proposed combining hydrometallurgy and pyrometallurgy processes. Finally, the properties of valuable metals products obtained by different treatment processes were discussed and analyzed, providing useful advice for the completely harmless treatment of waste Ni-based batteries.