BiSbx nanoalloys encapsulated by carbon fibers as high rate sodium ions storage anodes

BiSbx is a promising anode material for sodium ion batteries because of its merits in tolerating fast charge transfer during cycles. Here, a simple electrospinning is adopted to produce the BiSbx nanoalloys. One-dimensional (1D) carbon fibers with 30 - 50 nm BiSbx nanoparticles uniformly encapsulated inner (denoted as BiSbx@C) was fabricated. The as-prepared BiSbx@C anodes exhibit unexpected rate capability for sodium ions storage, withstanding a high current density of 20 A g-1 and delivering a reversible capacity of 500.2 mAh g-1 and 86.4% capacity retention after 100 cycles, which can be attributed to the bimetallic nanoalloys combined with 1D carbon that tolerate fast capacity fading during cycling and accommodate the volume expand during cycling. Specially, deeper understanding of the underlying mechanism of the Na+ ions storage and rapid transfer capability is civilized, which is vital to advance the sodium ions batteries for commercialization.