NaBO2/NaAlO2 dual-coating: A novel strategy for high-performance sodium-ion battery cathodes

Abstract

The development of cost-effective and resource-abundant sodium-ion batteries (SIBs) is crucial for large-scale energy storage and electric vehicle field. However, the commercial layered transition metal oxide cathodes in SIBs still face some drawbacks of inferior cycling stability, structural instability, and side reactions at the electrode-electrolyte interface. To overcome these limitations, a novel dual-surface coating strategy was developed by integrating NaBO₂ and NaAlO₂ coating layers onto NaNi_1/3Fe_1/3Mn_1/3O₂ (NFM) cathodes. The dual layers of NaBO₂ and NaAlO₂ effectively isolate the cathode from the electrolyte, while the outer NaBO₂ layer further enhances Na⁺ transport and stabilizes the solid electrolyte interface, thereby dramatically enhancing the structural stability of the NFM cathode. Coupling with the dual-modification strategy, NaBO₂/NaAlO₂-NFM exhibited much enhanced rate capability and cycling stability. It retains 73.3% of its initial capacity after 300 cycles at 50 mA g⁻¹, markedly outperforming B-NFM (42.6%) and bare NFM (33.7%). This work establishes a rational interface design principle-combining a physical barrier with an ion-conductive promoter-as a general and scalable route to project high-performance SIB cathodes, highlighting the pivotal role of precise interfacial control in next-generation battery technology.