Electrospun of CoSn nanoboxes@carbon nanotubes as free-standing anodes for high-performance lithium-/potassium-ion batteries

Herein, we report a novel structure with hollow CoSn alloy nanoboxes encapsulated in N-doped carbon nanotubes (CoSn@N-C nanotubes) for Li-ion batteries (LIBs) and K-ion batteries (PIBs). The structure is synthesized by an electrospinning method and subsequent calcination process. The obtained hollow N-doped carbon nanotubes not only effectively ensure the stability of CoSn alloys, but also accelerate ionic/electronic transport rate. Besides, the inner inactive Co and the hollow structure of CoSn nanoboxes can buffer the volume expansion of CoSn alloys during cycling. Benefiting from the hierarchical nanostructure and synergistic effect of the components, the electrodes demonstrate a reversible capacity of 653 mAh g-1 after 450 cycles in LIBs at 0.2 A g-1. Notably in PIBs, the CoSn@N-C nanotubes exhibits high rate capabilities up to 10 A g-1 and remarkable cycling life (178 mAh g-1 after 2000 cycles at 0.5 A g-1).