Electrochemical methods contribute to the recycling and regeneration path of lithium-ion batteries

Lithium-ion batteries (LIBs) are increasingly used in transportation, portable electronic devices and energy storage, with the number of spent LIBs increasing year by year. The various metal compounds contained in spent LIBs are a great hazard to the environment. Recycling spent LIBs can not only prevent environmental pollution but also meet the demand for various metal resources in the LIB market. But the variety of cathode materials and the mixing of unknown elements from production and utilization make the recovery more difficult and costly. Therefore, it is essential to explore a low-cost and efficient process for recycling spent LIBs. The methods of recycling spent LIBs include hydrometallurgy, pyrometallurgy, solid-phase regeneration and electrochemical methods, etc. The electrochemical methods for recycling spent LIBs have the advantages of high selectivity toward certain metal ions and are environmentally friendly. This review provides a comprehensive summary of the application of electrochemical methods in the disposal of spent LIBs, including pretreatment, leaching, element separation and regeneration. Applying the electrochemical method to the recycling of spent LIBs, replacing the traditional chemical leaching with the applied current as the reaction driving force, can greatly improve recycling efficiency while reducing reagent consumption and environmental hazards. The main obstacles of electrochemical methods in the recycling of spent LIBs and the solutions to these problems are discussed in detail. Finally, we comprehensively compare electrochemical methods with conventional recovery methods and propose a promising recovery process. We expect this review can provide a good idea for more efficient recycling of LIBs.