Carbon encapsulated FeS nanosheet-nanoribbon interwoven sandwich structure as efficient sodium-ion battery anodes

Carbon encapsulation and optimization of nanoparticle structure are key strategies in the development of battery electrode materials. Herein, we report a simple, one step chemical vapor deposition-like method to synthesize carbon encapsulated sandwich structured nanosheets/nanoribbons of ferrous sulphide (FeS@C NSRs) as a high performance sodium-ion battery anode material. The structurally advantageous FeS@C NSRs arises from heating Fe foam in the presence of a sulphur-containing resin, which supplies both the sulphur and carbon for the reaction. FeS@C NSRs maintains a high capacity of 582.8 mAh g−1 at 0.1 A g−1 for 120 cycles and a high rate capability of 270 mAh g−1 at 10 A g−1 for 2500 cycles. The impressive cycling performance results from fast electron and ion transfer with low structural strain on the bulk material. Furthermore, in situ Raman spectroscopy and XRD also reveal evidence that FeS@C NSRs cycles via a fully reversible conversion reaction pathway facilitated by the C–S–Fe bond. The efficient synthesis method could also be explored to produce other carbon coated transition metal sulphides for electrochemical applications.