Lattice Reconstruction and Surface Engineering Enable High‐Voltage Operation of Regenerated LiCoO 2 Cathodes

ABSTRACT Efficient recycling and high‐value regeneration of spent LiCoO 2 (LCO) cathodes are important for advancing lithium‐ion batteries (LIBs) recycling and promoting the sustainable utilization of critical resources. Here, we identify the intrinsic factors limiting the structural recovery of spent LCO (SLCO) and demonstrate that lattice reconstruction effectively restores both structural integrity and electrochemical stability at high voltages up to 4.6 V. We develop a multistep regeneration strategy that integrates selective impurity removal, lithium compensation, and high‐temperature solid‐state sintering to reconstruct the layered lattice and enhance Li + diffusion kinetics. Moreover, a uniform nanoscopic rock‐salt surface layer is deliberately engineered to suppress phase transitions and mitigate parasitic side reactions during high‐voltage cycling. Benefiting from these synergistic modifications, the regenerated LCO delivers good cycling stability, retaining 81.0% of its capacity after 1500 cycles at 2 C/4 C and achieving 121.3 mAh g −1 at 10 C under 4.6 V. This work provides a practical and scalable approach for regenerating SLCO cathodes with high‐voltage capability, offering new insights into green recycling and the sustainable development of LIBs cathode materials.