Box-like FeS@nitrogen-sulfur dual-doped carbon as high-performance anode materials for lithium ion and sodium ion batteries

Abstract Box-like FeS@nitrogen-sulfur dual-doped carbon (NSC) composite is synthesized through a typical solvothermal route, followed by carbonization at 500 °C in argon (Ar). When applied for Li-ion batteries (LIBs) and sodium ion batteries (SIBs), the FeS@NSC composite can deliver excellent rate capability and long-term cycling stability. Particularly, for LIBs, a high reversible discharge specific capacity of 611.8 mA h g−1 is achieved at a current density of 1 A g−1 after 250 cycles, much higher than that (185 mA h g−1) of its precursor FeS-FeS2 composite. When used for sodium storage, FeS@NSC composite keeps reversible discharge specific capacities of 473.2 and 356.2 mA h g−1 at a current density of 0.2 and 0.5 A g−1 after 100 cycles, respectively. Improved lithium and sodium storage performance of box-like FeS@NSC composite is attributed that NSC layer can enhance the electronic conductivity and the reactivity of FeS@NSC composite, and accommodate volume variations during electrochemical reactions. The remarkable lithium/sodium storage capacities of box-like FeS@NSC composite reveal its promising potential as anode materials for Li/Na-ion batteries.