Pillar-Effect-Stabilized Layered Oxide Sodium-Ion Battery Cathodes with Enhanced Air Stability and Processability

Abstract Air instability continues to severely impede the practical deployment of Na-layered oxides (NLOs) by necessitating extremely stringent dry-room handling during electrode processing. Although many approaches have been explored to improve air stability, economically viable and industrially compatible optimization routes directly applicable to already commercialized materials are still urgently needed. Herein, a Ca-pillar stabilization strategy is developed for O3-NaNi1/3Fe1/3Mn1/3O2 (NFM-Ca) via a facile mixing-and-recalcination process, simultaneously enhancing air tolerance, electrode processability, and cyclability. Systematic characterizations conducted under a controlled H2O/CO2-rich atmosphere reveal that Ca-pillaring effectively retards Na+/H+ exchange, thus inhibiting the formation of surface alkali residues and structural collapse. Consequently, NFM-Ca retains 93.6% of its initial capacity after 1 week of air exposure and remains processability even after prolonged air aging. This work offers a cost-effective strategy to improve the air tolerance and processability of NLOs, highlighting the importance of simultaneously considering air tolerance and cost-performance balance in cathode design.