Hierarchical carbon nanofibers@tin sulfide nanotube with sulfur‐doped carbon layer for ultrafast lithium‐storage capability

Summary Combining a high‐capacity material possessing a core@shell structure with a carbon material is a powerful tactic for reinforcing the performance of Li‐ion battery (LIB) anodes. As an efficient and simple approach to obtain tin(II) sulfide (SnS) with ultrafast lithium‐storage capability and cycling stability, we propose the hierarchical core@shell structure of carbon nanofibers@SnS nanotubes (CNF@SnSNTs) covered with S‐doped carbon via a one‐pot carbonization by harnessing the Kirkendall effect of camphene and sulfurization of SnO2 by L‐cysteine. This hierarchical core@shell structure contains mesoporous carbon nanofibers (CNFs) that reduce the Li‐ion diffusion pathway, SnS nanotubes (NTs) that expand the active site, and a S‐doped carbon layer at the faces of the SnS NTs that promotes the electrical conductivity and inhibits volume expansion of SnS. Therefore, a CNF@SnSNT‐C7 electrode achieves superb ultrafast electrochemical performance (528.1 mAh/g under a current density of 2000 mA/g), high specific capacity (2218.2 mAh/g under a current density of 100 mA/g), and an ultrafast cycling stability of 92.9% after 500 cycles under a current density of 2000 mA/g. These performance improvements are resulted from the synergistical effect of mesoporous CNFs, SnS NTs, and S‐doped carbon layer. Therefore, CNF@SnSNT is potential anode material for LIBs having superior Li‐storage capability. Hierarchical core@shell structure of carbon nanofibers@tin sulfide nanotube (CNF@SnSNT) with S‐doped carbon layer was successfully fabricated via one‐pot carbonization by the Kirkendall effect of camphene and sulfurization of SnO2 by L‐cysteine. Because of the SnS NTs having increased number of active sites, the specific capacity was increased. Also, owing to the mesoporous CNFs reducing the Li‐ion diffusion pathway, the ultrafast cycling capability was enhanced. Finally, because of the S‐doped carbon layers on the surface of the SnS NTs which prevent the volume expansion of SnS and increase the electrical conductivity, the ultrafast cycling stability was enhanced.