BiSb Alloy\nAnchored on Selenium Doped Carbon Nanofibers\nas Highly Stable Anode Materials for Sodium/Potassium-Ion Batteries

Sodium/potassium-ion\nbatteries (SIBs/PIBs) as alternatives complement\nof Li-ion batteries (LIBs) exhibit cost-effective, appropriate redox\npotential, and high energy density. Unfortunately, the large volumetric\nexpansion and severe pulverization toward anode materials of SIBs/PIBs\nduring the charge/discharge progress limit their practical implementations.\nIn this work, selenium doped carbon nanofibers integrated with bismuth–antimony\nalloy nanocrystals (denoted as BiSb-Se/CNFs) have been fabricated\nas anode materials for SIBs/PIBs. The hierarchical carbon nanofiber\nframeworks in BiSb-Se/CNFs composite not only provide sufficient space\nto accommodate Na/K ions, ensuring high structural stability, but\nalso facilitate rapid electron and ion transport, enhancing the redox\nreaction kinetic. As expected, the BiSb-Se/CNFs electrode demonstrates\na superior sodium storage capacity of 370 mAh g<sup>–1</sup> at current densities of 0.5 A g<sup>–1</sup> after 650 cycles,\nwithstanding a long-term cycling of 2000 cycles and showing a remarkable\ncapacity up to 309 mAh g<sup>–1</sup> at 2 A g<sup>–1</sup>. Moreover, an impressive potassium storage performance with a superior\ncapacity and outstanding reversible stability can be observed over\nthe BiSb-Se/CNFs electrode. This work elucidates the design of alloy-type\nelectrodes with a high lifespan in both SIBs and PIBs, which provides\ninspiration for practical multiapplication scenarios for anodes.