Acid assisted alcohol washing boosting efficient dealkalization and regeneration of Ni-rich cathodes

Ni-rich layered oxides are among the mainstream cathode active materials (CAMs) for advanced batteries due to high energy density. However, surface residual alkali (SRA) due to the high reactivity hinder their large-scale application. Water washing, a common industrial method to remove SRA tends to brings about Li loss and structural deterioration, which increases the difficulty and cost of industrial processing and leads to performance degradation. This study proposes a liquid-phase enhanced dealkalization strategy employing oxalic acid as an acidic agent and ethanol as solvent for efficient and minimally destructive SRA removal from air-exposed Ni-rich layered oxide LiNi_0.88Co_0.09Mn_0.03O₂. The in situ converted lithium oxalate (from SRA) is subsequently utilized as lithium source during low-temperature re-annealing to repair near-surface structural defects. This approach significantly improves Li-ion transport kinetics, enabling remarkable recovery of electrochemical performance. The regenerated cathode deliver a specific capacity of 173.38 mAh g⁻¹at 1 C—a substantial improvement from 136.93 mAh g⁻¹after air exposure (∼37 mAh g⁻¹enhancement), while maintaining 76.7% capacity retention after 200 cycles. This “waste-to-wealth” strategy presents an innovative pathway for scalable, low-damage dealkalization and short-process regeneration of high-activity cathode materials.