Nanostructured Fe2(MoO4)3 cathodes: Enhancing ion and electron kinetics for high-rate and low-temperature sodium-ion batteries

The nanostructured process effectively boosts the rate capability of Fe 2 (MoO 4 ) 3 . • The FMO-4.25 maintains a high capacity of 74.5 mAh g −1 at 100C. • Even at −20 °C, it retains 65 mAh·g −1 at 1C after 500 cycles. • In-situ EIS tracked interface kinetics evolution and CEI formation. Fe 2 (MoO 4 ) 3 (FMO), a promising polyanionic cathode material for sodium-ion batteries (SIBs), offers a stable three-dimensional framework, high operating voltage, and exceptional thermal stability, positioning it as a suitable candidate for large-scale energy storage systems. However, its practical implementation is still hindered by sluggish reaction kinetics. In this study, we address the issues of low electronic conductivity and slow Na + migration in FMO cathode material by an electrospinning-based nano-Synthesis strategy. By precisely regulating the pH of the precursor solution and optimizing the sintering process, the as-prepared FMO-4.25 electrode delivers a high specific capacity of 83.4 mAh·g −1 at 2C after 100 cycles and maintains a discharge capacity of 74.5 mAh·g −1 even at an ultrahigh rate of 100C. Moreover, it exhibits remarkable rate capability and long-term cycling stability even under low-temperature conditions. The electrochemical analysis reveals that the nano structuring of the FMO-4.25 electrode effectively enhances the kinetics of ion diffusion and electron transfer. Furtherover, the nanostructure effectively suppresses volume strain during Na + (de)intercalation, promotes the formation of a stable cathode-electrolyte interphase (CEI), and preserves the integrity of the interfacial and conductive networks, thereby synergistically improving the structural stability of the material. This work provides new insights into the controlled synthesis and mechanistic understanding of high-performance iron molybdate-based cathode materials, offering a valuable reference for advancing the practical application of SIBs in high-power and low-temperature environments. Download: Download high-res image (88KB) Download: Download full-size image