Electrospinning-assisted Ni doping activates maricite NaFePO4 for high-performance sodium-ion batteries

With 154 mAh g −1 of theoretical capacity and a stable polyanionic framework, NaFePO 4 shows considerable promise as a cathode material in sodium-ion battery systems. However, the maricite-type structure presents a high energy barrier for Na + migration, thereby restricting the electrochemical performance achievable in practice. Herein, an electrospinning-assisted Ni 2+ containing strategy is proposed to regulate the microstructural features and electronic properties of maricite-phase NaFePO 4 . Experimental investigations together with theoretical calculations reveal that introducing Ni 2+ reduces the band-gap width and enhances electronic conductivity. Meanwhile, the electrospun one-dimensional nanofibers construct continuous, shortened Na + transport pathways, leading to substantially faster ion-diffusion kinetics. Benefiting from this dual modulation, the optimized carbon-coated Ni-doped NaFePO 4 nanofiber cathode achieves 146 mAh g −1 at 0.1 C and retains 97.5% of its initial capacity after 100 cycles at 1 C. At an elevated rate of 20 C, the electrode still maintains 82.3% of its capacity after 5000 cycles, highlighting its excellent long-term cycling stability. The present study establishes an efficient activation route for maricite-type NaFePO 4 and offers a viable pathway toward cost-efficient and long-life cathode materials applicable to advanced sodium-ion battery systems.