Recycling cathode materials of spent lithium-ion batteries for advanced catalysts production

Spent lithium-ion batteries (LIBs) usually containing transition metals (e.g., nickel, cobalt, manganese) and toxic organic electrolytes can negatively affect the human health and environment. Exciting advances have been achieved in exploiting high efficiency, low cost, and environmentally-friendly processes for recycling spent LIBs. Until now, recycling electrode materials of spent LIBs has focused on the recovery of valuable metal resources that can be reutilized for production of new batteries or functional materials (e.g., catalysts). For the catalyst synthesis from spent LIBs, hydrometallurgical processes have been widely employed for recovery of transition metals compared to pyrometallurgical processes. Particularly, the recovered transition metal oxides such as CoOx and MnOx or their composites have more impact on catalysis applications, especially in the eletro- and photo-catalytic water splitting and organic pollutants degradation. Furthermore, the synthesis of transition metal-based compounds (e.g., oxides, oxyhydroxides, borides, phosphides, sulfides, nitrides) from spent LIBs should be developed to improve their photo-electro-catalytic activities in hydrogen evolution reaction (HER)/oxygen evolution reaction (OER). Additionally, the recovered transition metals can be used to improve the catalytic activity of other photo-catalysts (e.g., g-C3N4). “Waste-to-wealth” strategies of spent LIBs to catalysts would provide considerable benefits of environmental protection and functional materials synthesis in an efficient way.