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Abstract Developing suitable cathodes of sodium‐ion batteries (SIBs) with robust electrochemical performance and industrial application potential is crucial for the commercialization of large‐scale stationary energy storage systems. Layered sodium transition metal oxides, Na_xTmO₂(Tm representing transition metal), possessing considerable specific capacity, high operational potential, facile synthesis, cost‐effectiveness, and environmentally friendly characteristics, stand out as viable cathode materials. Nevertheless, the prevailing challenge of air‐induced degradation in most Na_xTmO₂significantly increases costs associated with production, storage, and transportation, coupled with a rapid decay in reversible capacity. This inherent obstacle inevitably impedes the advancement and commercial viability of SIBs. To address this challenge, it is essential to decode the chemistry of degradation caused by air exposure and develop protective strategies accordingly. In this review, a comprehensive and in‐depth understanding of the fundamental mechanisms associated with air‐induced degradation is provided. Additionally, the current state‐of‐the‐art effective protective strategies are explored and discuss the corresponding sustainability and scalability features. This review concludes with an outlook on present and future research directions concerning air‐stable cathode materials, offering potential avenues for upcoming investigations in advancing alkali metal layered oxides. 

Abstract Sodium all‐solid‐state batteries (NaSSBs) with an alloy‐type anode (e.g., Sn and Sb) offer superior capacity and energy density compared to hard carbon anode. However, the irreversible loss of Na⁺at the alloy anode during the initial cycle results in diminished capacity and stability, impairing full‐cell performance. This study presents an easy‐to‐implement cathode presodiation strategy by employing a Na‐rich material to address these challenges. Leveraging the high theoretical capacity and suitable voltage window, Na₂S is chosen as the Na donor, which is activated by creating a mixed electron‐ion conducting network, delivering a high capacity of 511.7 mAh g⁻¹. By adding a small amount (i.e., 3 wt.%) of Na₂S to the cathode composite, a NaCrO₂|| Sn full cell demonstrated capacity improvement from 90.8 to 118.2 mAh g⁻¹(based on cathode mass). The capacity‐balanced full cell can thus cycle to more than 300 times with >90% capacity retention. This work provides a practical solution to enhance the full‐cell performance and advance the transformation from half‐cell to full‐cell applications of NaSSBs. 

Binary nanoparticle superlattices (BNSLs) comprised of polymer-grafted shaped nanoparticles enable the construction of new isotropic mesomaterial.