Recovery of valuable metals from end-of-life Li-ion batteries: Technologies, progress, and perspectives

With the increasing demand for Li-ion batteries in electric vehicles and electronics, the recovery of valuable metals from spent Li-ion batteries (SLIBs) becomes crucial from both economic and environmental perspectives. However, there is a lack of holistic perspectives on developing sustainable technologies to advance the value chain of valuable metals from SLIBs. Thus, this review has systematically examined existing upstream and downstream technologies for metals recovery from SLIBs to figure out the trends of these technologies. For upstream recovery, the evolution of pyrometallurgical techniques was discussed, while applications of hydrometallurgical methods were comprehensively analyzed. Synthetic biology tools and metabolic engineering were recommended to enhance the tolerance of microorganisms in biohydrometallurgy towards its industrialization. We proposed that a tandem biological and hydrothermal leaching process could realize a robust and highly efficient metal leaching from SLIBs. Downstream separation technologies play a pivotal role in fractionation of metal ions. Membrane technologies are extensively compared for selective separation of specific metal ions and acids from SLIBs leachate. Despite the unique advantage in environmental friendliness over industrial solvent extraction and precipitation methods, an imbalance between selectivity and cost limits the commercialization of membrane technologies. Key features were specifically concluded for both conventional and emerging membrane processes. Through the analysis of the state-of-the-art and trends of industrial SLIBs recycling business, this review offers promising outlooks on technological development and industrialization based on the entire value chain. Eventually, this review promotes the recycling of valuable metals from SLIBs to a higher innovation level by adopting more sustainable and cost-efficient technologies.