Electrospun Nanofibrous Aluminum Doped Antimony/Carbon as a Universal Anode Material for Lithium and Sodium‐Ion Batteries

Abstract Antimony‐based anodes offer high theoretical capacities but face critical challenges such as severe volume expansion and poor cycle life in rechargeable batteries. Developing a suitable dopant for Sb‐based anodes and integrating these materials with nanofiber architectures presents a promising pathway to address these limitations. This study investigates the effect of Al doping in Sb alloy‐based nanofibers by comparing antimony nanofibers (Sb‐NF) with aluminum‐doped Sb‐NF (Sb 0.95 Al 0.05 ‐NF). In lithium‐ion batteries (LIBs), Sb‐NF remains electrochemically active up to a 10 C‐rate, while Sb 0.95 Al 0.05 ‐NF sustains cyclability even at 30 C‐rate, delivering 73.9 mAh g −1 . For sodium‐ion batteries (SIBs), both anodes function up to 25 C‐rate, but Sb 0.95 Al 0.05 ‐NF achieves a reversible capacity of 117 mAh g −1 , significantly outperforming Sb‐NF, which delivers 50 mAh g −1 . Long‐term cycling studies on LIB show that Sb 0.95 Al 0.05 ‐NF retains nearly three times the capacity of Sb‐NF after 300 cycles, with capacity retention of 14% and 9%, respectively. In SIBs, Sb 0.95 Al 0.05 ‐NF exhibits superior performance up to 200 cycles, however, both Sb‐NF and Sb 0.95 Al 0.05 ‐NF electrodes are affected by electrolyte related degradation including sodium dendrite formation beyond 200 cycles. Cyclic voltammetry reveals higher diffusion coefficients for Sb 0.95 Al 0.05 ‐NF in both LIB and SIB configuration. These findings highlight the synergetic benefits of doping and nanofiber morphology in improving rate capability and cycling stability.