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

Marcasite FeS 2 hollow microspheres were selectively synthesized by a simple hydrothermal method . Time-dependent evolution reveal that marcasite FeS 2 hollow microspheres is formed attributed to the phase transformation from greigite Fe 3 S 4 into marcasite FeS 2 with Ostwald ripening mechanism. The hollow marcasite FeS 2 exhibits excellent electrochemical performance as the anode of sodium ion batteries (SIBs). Significantly, the FeS 2 (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 FeS 2 (M) hollow microsphere electrodes are investigated by the in-depth kinetics analysis. Our results demonstrate the marcasite FeS 2 hollow microspheres would be a promising anode material for SIBs.