Sustainable Revival of Spent Ni‐Rich Cathodes: High‐Temperature Endurance and Accelerated Kinetics via Strategic Upcycling

Abstract The paradigm shift toward the disposal of retired batteries demands sustainable and cost‐effective recycling methods that surpass conventional pyro‐/hydrometallurgy‐based techniques, offering superior profitability, energy efficiency, resource utilization, and environmental benefits. In this study, a one‐step modulation approach is presented for regenerating spent Ni‐rich layered oxides featured with exceptional ion diffusivity and high‐temperature stability. By exploiting decomposed species from Li 6 Zr 2 O 7 , monitored via high‐temperature X‐ray diffraction, the strategy simultaneously enables: Li source replenishment, Zr doping into the bulk lattice, and Conformal ion‐conductive Li 2 ZrO 3 coating on regenerated LiNi 0.8 Co 0.1 Mn 0.1 O 2 (R‐NCM811‐2%LZO). Crucially, the upcycling process strategically utilizes lattice vacancies in the oxide to facilitate Zr dopant diffusion, while Li 2 ZrO 3 coating elevates corrosion resistance and thermal stability. Operando phase tracking reveals that the regenerated cathode maintains reversible lattice breathing and undergoes a continuous, kinetics‐boosted phase transition. By pairing R‐NCM811‐2%LZO cathode with graphite anode in a 3.0 Ah pouch‐format cell, the prototype achieves an energy density of 302 Wh kg −1 , extreme power output of 1260 W kg −1 , 63% mitigation of self‐discharge rate at 55 °C, as well as robust cycling across a wide temperature range. This value‐added strategy upgrades spent NCM811 into high‐temperature‐tolerant, fast‐charging cathodes, paving the way for sustainable battery recycling and circular economy initiatives.