Recycling spent lithium-ion battery cathode: an overview

The past decades have witnessed the rapid development of lithium-ion batteries (LIBs), which are applied in nearly every aspect of our daily life. However, the increasing number of spent LIBs (S-LIBs) poses a great threat to the environment. Thus, to protect the environment and preserve limited lithium resources, it is necessary to recycle S-LIBs. In this review, we initially provide a brief introduction on the structure and degradation mechanism of LIBs and pretreatment of S-LIBs. Subsequently, we highlight the recent advancements in the development of recycling the cathode of S-LIBs, including its direct, hydrometallurgical, and pyrometallurgical recovery. The advantages and disadvantages of each recycling process are also discussed from the viewpoint of the environment and economy. In addition, we also introduce the recycling of S-LIBs through a green and environmentally friendly process of treating waste with waste. Finally, the overall perspective of this technology and areas requiring particular attention in the future are discussed. This review introduces the structure and failure mechanism of lithium-ion batteries, followed by a systematic summary of recycling techniques, including direct, hydrometallurgical, and pyrometallurgical recovery.