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.

Automated summary

Three-dimensional porous FeS@N-doped carbon nanosheets were successfully synthesized using a sol-gel method and solid sulfidation process. These nanosheets demonstrated excellent electrochemical performance as anodes for sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs), with outstanding cycling stability and rate behavior. The unique structure of the nanosheets inhibits aggregation and pulverization of FeS, enhances conductivity, immobilizes dissolved polysulfides, and increases the contact area between active materials and electrolytes. The N-doped carbon framework also provides abundant active sites for Na+(K+) storage.