BiSb Alloy Anchored on Selenium Doped Carbon Nanofibers as Highly Stable Anode Materials for Sodium/Potassium-Ion Batteries

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