Targeted Etching of Heterogeneous Phases and Crystal‐Induced Regrowth for Direct Single‐Crystal Regeneration of Spent Cathode Materials

Abstract The recycling of spent lithium‐ion batteries is a critical link in the global transition to new energy systems. Direct single‐crystal regeneration has emerged as a key research direction for recycling of spent cathode materials, yet it faces inherent conflicts between high‐temperature kinetics for single‐crystal transformation and structural stability, and the dilemma of balancing particle fragmentation with crystal integrity. Herein, the study presents a strategy of targeted etching of heterogeneous phases and crystal‐induced regrowth to achieve efficient single‐crystal regeneration of spent cathode materials. In the molten salt‐mediated system, the precise etching of the rock‐salt phase via Cl − penetration induces local lattice distortion and stress accumulation, leading to the controlled and oriented cleavage of polycrystalline particles. Leveraging the strong ion migration effect, this process facilitates simultaneous relithiation and single‐crystal regeneration. Owing to the restored morphological and structural integrity, the regenerated single‐crystal cathode delivers a high initial discharge capacity of 183.60 mAh g −1 at 1C and an exceptional capacity retention of 93% after 100 cycles. Economic and environmental analysis further confirms the significant cost advantage of this strategy over conventional pyrometallurgical and hydrometallurgical recycling routes. This study provides an innovative solution for the direct regeneration of cathode materials in spent lithium‐ion batteries.