Electrochemical Recycling of Spent Lithium-Ion Battery Cathodes: Direct Regeneration, Electrochemical Leaching, and Selective Separation

Growing volumes of spent lithium-ion batteries challenge waste management and resource security. Conventional recycling recovers metals but often consumes energy and chemicals while sacrificing cathode structural value. Electrochemical methods enable cathode repair, controlled dissolution, and selective recovery, yet their suitability for diverse feeds and product requirements remains unclear. This Critical Review develops a material-state- and product-oriented framework linking cathode degradation, electrochemical transformations, and product specifications. Relithiation, defect repair, and cell-level rejuvenation are evaluated as regeneration strategies, with functional repurposing considered separately. Electrochemical leaching is classified by direct or indirect redox transfer, while paired or coupled operation is treated as reactor-level integration. Electrodialysis, electrosorption, and electrodeposition are assessed for ion redistribution, selective capture, concentration, and product formation. Because extraction efficiency alone cannot establish successful recycling, we emphasize feedstock tolerance, selectivity, Faradaic and ion-transport efficiencies, energy and reagent consumption, component durability, and qualified-product yield within defined system boundaries. Future priorities include diagnosis-guided routing, realistic black-mass validation, standardized reporting, scalable reactors, and integrated techno-economic and life-cycle assessment. Electrochemical technologies can complement established recycling through feedstock-adaptive pathways that retain, recover, or upgrade cathode value.