Anchoring-Induced Interphase via Dual Mortise-Tenon Interactions for Synergistic Stabilization of Surface Co and O in...

Interfacial instability of LiCoO₂ (LCO) above 4.6 V remains a bottleneck for high-energy-density batteries due to the coupled Co dissolution and O release. Here, inspired by mortise-tenon structures, we propose a dual-site cooperative anchoring strategy targeting Co and O lattice sites via atomic orbital-level interactions. Through screening based on electronic structure and geometric compatibility, phenylmethylsulfonyl fluoride (PMSF) was identified as an optimal additive. Owing to its high HOMO level and precise spatial matching, PMSF undergoes site-specific sacrificial oxidation prioritized at the LCO surface lattice. This dual-site docking achieves directional orbital overlap with the surface Co and O sites, effectively lowering the activation energy for the formation of a uniform, ion-conductive, and thin (∼5 nm) cathode electrolyte interphase. The resulting interphase acts as a robust chemical shield that suppresses Co dissolution and O loss simultaneously. As a result, LCO half-cells with 0.3 wt% PMSF retained 61.9% capacity after 200 cycles at 4.8 V. Moreover, 1 Ah graphite||LCO pouch cells maintained 99.5% and 79.6% capacity after 300 and 600 cycles at 4.6 V, respectively. These findings demonstrate that dual-site anchoring provides a pivotal guiding principle for transitioning from disordered decomposition to controlled, site-specific interfacial assembly for next-generation high-voltage cathodes.