Advanced Alkali-Activated Persulfate Preoxidation Strategy for Efficient Regeneration of Degraded Ternary Cathode Materials

Direct regeneration of spent layered cathodes is a promising strategy for sustainable lithium-ion battery recycling, yet their practical implementation is often restricted by the severe interfacial and structural degradation of Ni-rich layered cathode materials. Under alkaline conditions, K 2 S 2 O 8 generates reactive sulfate and hydroxyl radicals, which partially decompose PVDF-derived interfacial residues and oxidize the reduced surface Ni species. These reactions attenuate the fluorinated surface coverage and suppress rock-salt-like reconstruction, thereby producing a more structurally ordered preactivated surface. After subsequent high-temperature sintering, the regenerated LiNi 0.83 Co 0.12 Mn 0.05 O 2 (NCM83) exhibits a well-restored layered structure, delivering a high discharge capacity of 205.3 mAh g –1 and a capacity retention of 87.8% after 300 cycles. Without alkali-activated persulfate preoxidation, the regenerated NCM cathode presents higher residual structural disorder and inferior electrochemical performance, retaining only 72.2% of its capacity after 300 cycles. This work demonstrates that radical-assisted surface preactivation is an effective route to overcome relithiation limitations in direct cathode regeneration.