Rational synthesis of marcacite FeS2 hollow microspheres for high-rate and long-life sodium ion battery anode

Abstract Marcasite FeS2 hollow microspheres were selectively synthesized by a simple hydrothermal method. Time-dependent evolution reveal that marcasite FeS2 hollow microspheres is formed attributed to the phase transformation from greigite Fe3S4 into marcasite FeS2 with Ostwald ripening mechanism. The hollow marcasite FeS2 exhibits excellent electrochemical performance as the anode of sodium ion batteries (SIBs). Significantly, the FeS2 (M) hollow microspheres deliver a high specific discharge capacity of 363 mA h g−1 at 100 mA g−1 after 300 cycles. They also still deliver high-rate and long-life performance with a specific discharge capacity of 280 mA h g−1 at a high current density of 1000 mA g−1 after 1000 cycles. Moreover, the high rate capability and long cycling stability of the FeS2 (M) hollow microsphere electrodes are investigated by the in-depth kinetics analysis. Our results demonstrate the marcasite FeS2 hollow microspheres would be a promising anode material for SIBs.