A review of research progress on combined pyro-hydrometallurgical technology for spent lithium-ion batteries

In the past, metal mineral resources were extracted to produce widely used lithium-ion batteries. Today, the transformation of valuable metals from spent lithium-ion batteries into reusable resources has become a critical field of research. This review article outlines recent advancements in combined pyro-hydrometallurgical technologies for recycling spent LIBs. It begins with an analysis of the evolution of LIB recycling policies in the European Union, the United States and China, highlighting China's implementation of specific and targeted measures to enhance its lithium-ion battery recycling infrastructure over the past decade. An environmental impact assessment reveals that combined pyro-hydrometallurgical techniques can significantly reduce the temperatures required for pyrometallurgical processes and minimize the reliance on chemicals in hydrometallurgical operations, thus holding substantial promise for reducing environmental emissions. Furthermore, this review examines oxygen-free roasting, molten salt-assisted roasting and biomass reduction roasting within the framework of combined pyro-hydrometallurgical technologies. Finally, it provides an outlook on the field of spent lithium battery recycling, offering valuable references and guidance for future development.