Multiscale Structural Recovery of Spent NCM Cathodes through W-Doping-Assisted Regeneration

The rapid growth of Li-ion battery consumption has led to an increasing number of spent batteries, posing serious challenges to resource sustainability and environmental protection. This study develops a low-carbon, W-doping-assisted direct regeneration strategy for spent LiNi 0.5 Co 0.2 Mn 0.3 O 2 (NCM523) cathode materials, aiming to realize simultaneous lattice restoration, microstructural reconstruction, and interfacial stabilization. The regeneration process involves hydrothermal relithiation combined with W incorporation and high-temperature annealing. Comprehensive characterizations, including XRD, XPS, SEM, HRTEM, EPR, and electrochemical analyses, reveal that the proposed method effectively reconstructs the layered R 3̅ m structure and recovers long-range order while eliminating impurity phases. W incorporation enhances structural integrity by forming robust W–O bonds, suppressing oxygen vacancy formation, mitigating Li/Ni cation mixing, and reducing microcrack propagation. Furthermore, the regeneration process restores the high oxidation states of transition metals (Ni 3+, Co 3+, Mn 4+ ), thereby stabilizing the lattice and improving charge-transfer kinetics. The regenerated cathode exhibits a high initial discharge capacity of approximately 163 mA·h·g –1, reduced polarization, and excellent cycling stability comparable to or surpassing that of fresh NCM523. Overall, this work demonstrates that W-doping-assisted direct regeneration provides an effective and sustainable pathway for multiscale structural recovery of spent NCM cathodes, promoting high-value utilization in circular battery recycling.