Harnessing Temperature‐Mediated Strain Management to Realize Ultra‐Stable Oxide Cathodes in Na‐Ion Batteries

ABSTRACT Sodium (Na)‐ion batteries (NIBs) are emerging as a promising solution for large scale energy storage applications. Among various cathode chemistries, O3‐phase layered transition‐metal oxides stand out for their high energy density, yet their practical deployment is restricted by intricate phase transitions that induce lattice distortion, stress accumulation, and particle cracking, leading to rapid performance degradation. Here, we propose a temperature‐mediated strain‐management strategy to improve the phase reversibility and structural stability of O3‐phase oxide cathodes. Comprehensive structural and dynamic analyses reveal that optimal thermal regulation facilitates lattice strain release, mitigates detrimental stress accumulation that drives irreversible phase transitions, and accelerates Na + diffusion kinetics. As a result, structural degradation, transition‐metal dissolution, and capacity fading are effectively suppressed. This work provides a new perspective on employing external fields to overcome the intrinsic structural instability of layered oxides, offering fundamental insights for rational cathode design and reliable operation of practical NIBs for energy storage.