▎ 摘　　要

The composite of carbon materials and transition metal sulfides can significantly improve the poor cycling performance of transition metal sulfides in sodium storage. In this study, the nitrogen/sulfur co-doped three-dimensional graphene (NSGN) encapsulating transition metal sulfides (FeS, Co9S8 and Ni3S2) are designed in a general method to improve the poor cycling stability of transition metal sulfides. The desired anode materials all show an excellent cyclic stability with the capacity retention of 63%, 97% and 98% after 100 cycles in sodium-ion batteries for FeS@NSGN, Co9S8@NSGN and Ni3S2@NSGN electrodes, respectively. Consequently, this work can provide a new insight for in-situ synthesis of metal sulfides and graphene composites to improve the performance of sodium storage.