Emerging Strategies for Spent Li-Ion Battery Recycling: Progress and Perspectives of Redox-Mediated Methods

The exponential growth of the electric vehicle (EV) market has triggered a massive accumulation of spent lithium-ion batteries (sLIBs), which urgently requires sustainable recycling strategies to reduce environmental risks and ensure the availability of key mineral resources. While traditional pyrometallurgical and hydrometallurgical processes are established for large-scale operations, they are limited by high energy consumption, high reagent consumption, and hazardous secondary emissions. This review systematically evaluates current recycling methods, ranging from traditional smelting and acid-leaching to emerging electrochemical paradigms. A primary focus is placed on the redox-mediated method, a transformative electrochemical strategy designed to overcome the high energy consumption of traditional strategies and the inherent kinetic limitations in direct electrochemical extraction. This method introduces a redox mediator that decouples the electrochemical reaction into the mediator regeneration reaction at the electrode interface and the delithiation reaction at the solid-liquid interface, thereby enabling efficient and targeted energy-supplying recycling. Furthermore, the redox mediator recovery method can be ingeniously combined with value-added processes such as hydrogen production and zinc deposition, significantly reducing energy consumption and carbon footprint compared to traditional methods. This article shows the value of the redox mediator method, which combines waste treatment and resource regeneration.