A Comprehensive Review on Reductive Recycling of Cathode Materials of Spent Lithium‐Ion Batteries

The prosperity of the lithium‐ion battery market is inevitably accompanied by the depletion of corresponding resources and the accumulation of spent batteries in a dialectical manner. Spent lithium‐ion batteries are harboring the characteristics of hazardous waste and high‐value resources, so efficient recycling is of great significance. The cathode material is considered as an interesting target for repurposing. Despite some important reviews give commendable emphasis to recycling technologies, there is still a dearth of exploration of recycling mechanisms. This deficiency of awareness highlights the need for further research and development in this area. This review aims to systematically review and thoroughly discuss the reduction reaction mechanism of each method regarding different cathode materials. And systematically digest the selection of reducing agent and the effect of reduction reaction on material regeneration are systematically digested, as well as the impact of the reduction reaction on the regeneration of materials. This review emphasizes the importance of balancing efficiency, economic and environmental benefits in reuse technologies. Finally, the review proposes an outlook on the opportunities and challenges facing the reuse of key materials for next‐generation spent batteries aimed at promoting the green and sustainable development of lithium‐ion batteries, circular economy and ecological balance. This review aims to digest lithium‐ion battery cathode material recycling and regeneration methods based on the reduction reaction mechanism. It discusses several reductants commonly used in the recycling process, and introduces some recently proposed direct regeneration methods. Finally, it concludes and outlooks the battery recycling based on the reduction reaction mechanism.