Single-precursor-enabled surface/near-surface engineering for stabilizing oxygen redox in high-voltage Li-rich layered cathodes

Li-rich layered oxide cathodes offer high energy density but suffer from severe oxygen-related structural degradation and interfacial instability under high-voltage cycling. Herein, ammonium tetrathiomolybdate ((NH 4 ) 2 MoS 4 ) is employed as a multifunctional precursor to regulate the surface and near-surface chemistry of Li-rich cathodes through facile thermal treatment. The resulting S-LRO cathode features a MoS x -derived interphase coupled with a reconstructed subsurface region, where spinel-like domains, modulated oxygen-defect environments, and Mo O interactions are simultaneously generated. This integrated architecture stabilizes lattice oxygen activity, suppresses transition-metal migration, mitigates anisotropic lattice strain, and restrains the continuous growth of cathode-electrolyte interphase during prolonged cycling. Consequently, S-LRO delivers enhanced rate capability and durable cycling performance, maintaining 81.8% capacity retention after 400 cycles at 1C and 79.4% after 200 cycles at 45 °C. Furthermore, the fully delithiated S-LRO electrode exhibits significantly improved thermal stability, with the exothermic onset temperature increased by 69.5 °C compared with the pristine counterpart. This work demonstrates an effective surface/near-surface regulation strategy for mitigating oxygen-related degradation and interfacial failure in high-energy Li-rich layered cathodes.