Encapsulating Sn_xSb Nanoparticles in Multichannel Graphene-Carbon Fibers As Flexible Anodes to Store Lithium Ions with High Capacities

SnxSb intermetallic composites as high theoretical capacities anodes for lithium ion batteries (LIBs) suffer from the quick capacity fading owing to their huge volume change. In this study, flexible mats made up of SnxSb-graphene-carbon porous multichannel nanofibers are fabricated by an electrospinning method and succedent annealing treatment at 700 °C. The flexible mats as binder-free anodes show a specific capacity of 729 mA h/g in the 500th cycle at a current density of 0.1 A/g, which is much higher than those of graphene-carbon nanofibers, pure carbon nanofibers, and SnxSb-graphene-carbon nanofibers at the same cycle. The flexible mats could provide a reversible capacity of 381 mA h/g at 2 A/g, also higher than those of nanofibers, graphene-carbon nanofibers, and SnxSb-carbon nanofibers. It is found that the suitable nanochannels could accommodate the volume expansion to achieve a high specific capacity. Besides, the graphene serves as both conductive and mechanical-property additives to enhance the rate capacity and flexibility of the mats. The electrospinning technique combined with graphene modification may be an effective method to produce flexible electrodes for fuel cells, lithium ion batteries, and super capacitors.