FeS/ZnS nanoflower composites as high performance anode materials for sodium ion batteries

The electrochemical performance of composite materials can be effectively improved by regulating multiple components and designing well-defined microstructure. In this work, FeS/ZnS composites with different Fe/Zn ratios were prepared through a facile wet chemical method. The as-prepared sulfide composite with molar ratio Fe/Zn = 1 exhibits optimal nanoflower morphology and achieves a high specific capacity as sodium-ion battery anode with reversible capacity of 475.1 mA h g(-1) after 50 cycles at a current density of 100 mA g(-1). Moreover, even at a high current density of 2000 mA g(-1), a stable capacity of 207.6 mA h g(-1) can be obtained. The superior electrochemical performance can be attributed to the design of optimal nanoflower structure through the regulation of Fe/Zn ratio, and the nanostructure can efficiently buffer volume change during discharge-charge, shorten Na+ diffusion pathways, promote the electrode/electrolyte contact, and thus render the sulfide composite FeS/ZnS a promising anode material for advanced sodium-ion batteries.