Free-standing SnS/C nanofiber anodes for ultralong cycle-life lithium-ion batteries and sodium-ion batteries

The development of flexible energy storage devices is the key to widen the application of flexible electronics and wearable devices. Flexible electrodes with superior electrochemical performance are critical components for flexible energy storage devices. Herein, we propose a simple and versatile electrospinning strategy to prepare the SnS/C nanofibers (SnS/C NFs) film. By using SnS/C NFs film directly as a free-standing anode in both lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs), it can provide outstanding electrochemical performance. For LIBs, it delivers high capacities of 648 and 548 mA h g^-1 at 200 and 500 mA g^-1 respectively after 500 cycles. It even shows outstanding cyclability for 1000 cycles. For SIBs, it retains capacity of 481 mA h g^-1 after 100 cycles at 50 mA g^-1. Moreover, the capacity remains as high as 349 mA h g^-1 at 200 mA g^-1 after 500 cycles. The outstanding electrochemical performance is mainly attributed to the fact that the fine SnS nanoparticles dispersed in one-dimensional porous nanofibers with uniform diameters around 130 nm shorten the transport path of ions and electrons, and the presence of N-doped carbon enhanced the electrical conductivity as well as relieve the volume change caused by the alloying/de-alloying reaction. Besides, the ultra-robust mechanical flexibility of SnS/C NFs film makes it a promising anode candidate for flexible LIB and SIB in future.