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

LIBs are widely used in portable electronics, but their application in grid-scale energy storage is limited due to lithium’s high cost and resource constraints. As a more affordable alternative, Sodium-ion batteries (SIBs) offer the promise of large-scale deployment. Among various cathode materials, O3-type NaNi0.4Fe0.2Mn0.4O2 (NFM424) demonstrates high capacity and ease of synthesis, yet suffers from structural degradation and sluggish Na+ kinetics caused by large ionic radius and strong electrostatic interactions. To overcome these issues, a configuration strategy combined with TiO2 and Co3O4 was introduced to improve structural and electrochemical stability. The resulting NaNi0.4Fe0.2Mn0.3Co0.05Ti0.05O2 (NFMCT) cathode mitigated Jahn-Teller distortions and Na+/vacancy ordering while enhancing phase integrity and diffusion pathways. Synthesized via high-temperature solid-state reaction, NFMCT achieved a high initial Coulombic efficiency of 106.14% and maintained 93.7 mAhg-1 after 550 cycles at 1C, with superior rate capabilities at 2C and 5C. These findings deepen the understanding of configuration strategy by using multi-element oxide and highlight a practical strategy for designing high-performance SIB cathodes.