High Rate Performance of Single‐Crystalline NCM Upcycled from Spent Lithium‐Ion Batteries Via Direct Recovery and Modification

Abstract The global expansion of spent lithium‐ion batteries (LIBs) presents both an urgent environmental issue and a significant economic opportunity, driving the development of diverse recycling processes worldwide. Direct regeneration is a promising method for recovering materials from spent LIBs. However, most existing direct regeneration methods focus solely on recovering cathodes without addressing further improvements in their performance. Herein, a direct regeneration method is reported to upcycle single‐crystalline lithium nickel manganese cobalt oxides (NCM) from spent polycrystalline NCM based on a facile phosphoric acid etching approach. Moreover, the Li₃PO₄ coating and PO₄³⁻ polyanion doping are simultaneously achieved on the surface of single‐crystal NCM during the upcycling single‐crystalline process. The enlarged lattice spacing and fast ionic conductor coating layer enhance Li⁺ diffusion and mitigate phase transformations during delithiation/lithiation. Benefiting from the synergistic effect of single crystal structure and surface modification, the upcycled single‐crystalline LiNi_0.65Co_0.2Mn_0.15O₂ demonstrates excellent electrochemical performances, including large reversible capacity (≈186 mAh g⁻¹ at 0.1C), high‐rate capability (≈142 mAh g⁻¹ at 10C), and excellent cycling stability (≈99% retention for 100 cycles). This approach provides a novel and effective upcycling pathway to transform the spent LIBs into value‐added cathode materials, achieving a win–win situation for environmental protection and resource conservation.