Understanding of TiO2/Co3O4-modified configuration strategy for stabilizing O3-type NaNi0.4Fe0.2Mn0.4O2 cathodes with enhanced long-term and rate performance

• A TiO2/Co3O4-modified configuration strategy significantly enhances the structural and electrochemical stability of O3-type NaNi0.4Fe0.2Mn0.4O2 cathodes. • The resulting NFMCT cathode mitigates Jahn-Teller distortions and Na+/vacancy ordering, improving phase integrity and Na+ diffusion pathways. • NFMCT delivers a high reversible capacity of 93.7 mAh·g−1 after 550 cycles at 1 C, with superior rate performance at 2 C and 5 C. • This work provides a practical and cost-effective strategy for designing high-performance sodium-ion battery cathodes.