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

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 Li₆Zr₂O₇, monitored via high-temperature X-ray diffraction, the strategy simultaneously enables: Li source replenishment, Zr doping into the bulk lattice, and Conformal ion-conductive Li₂ZrO₃ coating on regenerated LiNi_0.8Co_0.1Mn_0.1O₂ (R-NCM811-2%LZO). Crucially, the upcycling process strategically utilizes lattice vacancies in the oxide to facilitate Zr dopant diffusion, while Li₂ZrO₃ 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.