Suppressing Lattice Oxygen Release and Mitigating Mechanical Stress Buildup in Co-Free LiNiO₂Cathodes

Cobalt-free LiNiO₂ (LNO) layered oxide cathodes are now positioned as a leading candidate for next-generation high-energy-density batteries, owing to their cost efficiency and ultra-high-capacity. Nevertheless, the coupled mechanical–electrochemical instability and thermally induced lattice oxygen evolution under extreme operating temperatures critically restrict their commercial deployment. Herein, we employ a high-valence W⁶⁺ doping strategy to alleviate lattice stress in the LNO during high-temperature operation. Simultaneously, this modification markedly strengthens the anchoring of surface lattice oxygen, effectively inhibiting oxygen release from the bulk structure. The W-doped LNO cathode demonstrates an initial discharge capacity of 236.9 mAh g^–1 at 0.1 C under harsh 45 °C conditions. Remarkably, the modified electrode retains 77.6% of its capacity after 100 cycles, surpassing that of the pristine LNO, which suffers severe capacity degradation (65.4% retention) under identical testing protocols. This study presents critical strategic insights into the practical implementation of cobalt-free layered LNO cathodes under high-temperature operational environments.