Direct Regeneration of Spent LiNi_0.8Co_0.1Mn_0.1O₂ into Ce-Doped Single-Crystal Cathodes

The widespread deployment of lithium-ion batteries (LIBs) is driving a steep rise in end-of-life batteries, heightening resource and environmental burdens and underscoring the need for efficient recycling. Direct regeneration, with its simplified processing, offers a practical alternative to conventional pyrometallurgical and hydrometallurgical routes. Herein, we directly regenerate spent polycrystalline LiNi_0.8Co_0.1Mn_0.1O₂ (S-NCM811) into single-crystal cathodes with uniformly distributed Ce through mechanical deagglomeration-assisted eutectic molten salt regeneration. Lithium is replenished through fast ionic transport in the molten salt, while the surface NiO rock salt phase is relithiated and reconstructed into the layered structure. Notably, Ce doping expands the interlayer spacing and enhances the structural stability of regenerated LiNi_0.8Co_0.1Mn_0.1O₂ (R-NCM811). In situ X-ray diffraction and electrochemical impedance spectroscopy confirm that Ce-doped single-crystal R-NCM811 alleviates H2→H3 lattice distortion and maintains lower charge-transfer resistance. As a result, R-NCM811 exhibits improved electrochemical performance, delivering 159.5 mAh g^-1 at 5 C and retaining 88.17% of its capacity after 300 cycles at 1 C. This work establishes a viable upcycling strategy for regenerating single-crystal cathodes and provides a practical pathway toward more sustainable battery recycling.