Three-dimensional porous FeS@N doped carbon nanosheets for high-rate and high-stable sodium/potassium storage

The three-dimensional (3D) FeS@N doped Carbon (NC) nanosheets are successfully synthesized using a simple sol-gel method followed by a solid sulfidation process. As SIBs anode, the 3D FeS@NC nanosheets exhibit a maintainable capacity (254 mAh g −1 at 1.5 A g −1 upon 1100 cycles) and outstanding rate behaviour. As PIBs anode, the 3D FeS@NC nanosheets also exhibit a maintainable capacity (120 mAh g −1 at 1 A g −1 upon 1100 cycles) and outstanding rate behaviour. The excellent electrochemical performance can be attributed to the distinctive 3D porous FeS@NC nanosheets, which can inhibit the aggregation and pulverization of FeS, enhance electronic/ionic conductivity, firmly immobilize the dissolved polysulfides , and provide a larger contact area between active materials and electrolytes. Moreover, the N-doped carbon framework can also provide substantial active sites for Na + (K + ) storage. Our synthesizing strategy can be potentially utilized for fabricating other 3D metal sulfide@C composites for SIB (PIB) anodes.