Gradient selenium-doping regulating interfacial charge transfer in zinc sulfide/carbon anode for stable lithium storage.

Metal sulfides have attracted much attentions as anode materials for lithium-ion batteries (LIBs) because of the high theoretical capacity. However, the poor electronic conductivity and large volume variation usually give rise to the rapid capacity decay and undesirable rate performance, severely hampering their practical application. Herein, a gradient selenium-doped hollow sandwich structured zinc sulfide/carbon (ZnS/C) composite (Se-HSZC) is designed and fabricated as long life-span and stable anode material for LIBs. The gradient Se-doping enhances the interfacial charge transfer in Se-HSZC, while the unique double carbon shell sandwich structure further greatly reduces the volume expansion and ensures the electron fast transportation. Consequently, the Se-HSZC anode presents outstanding rate capability (654 mAh g-1 at 2 A g-1) with remarkable reversible capacity (567 mAh g-1 after 1500 cycles at 4 A g-1) for the half battery. In particular, a reversible capacity of 457 mAh g-1 at 0.5 A g-1 is achieved after 50 cycles for the full battery with LiNi0.6Co0.2Mn0.2O2 as cathode. This work offers a promising design route of novel metal sulfides nanostructures for high performance LIBs.