Improved Electrochemical Performance of Na-Ion Batteries in Ether-Based Electrolytes: A Case Study of ZnS Nanospheres

Sodium-ion batteries are considered as a promising technology for large-scale energy storage applications, owing to their low cost. However, there are many challenges for developing sodium-ion batteries with high capacity, long cycle life, and high-rate capability. Herein, the development of high-performance sodium-ion batteries using ZnS nanospheres as anode material and an ether-based electrolyte, which exhibit improved electrochemical performance over the pure alkyl carbonate electrolytes, is reported. ZnS nanospheres deliver a high specifi c capacity of 1000 mA h g(-1) and high initial Columbic effi ciency of 90%. Electrochemical testing and fi rst-principle calculations demonstrate that the ether-based solvent can facilitate charge transport, reduce the energy barrier for sodium-ion diffusion, and thus enhance electrochemical performances. Ex situ measurements (X-ray diffraction (XRD), fi eld emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) mapping) reveal that ZnS nanospheres maintain structural integrity during the charge and discharge processes over 100 cycles. As anode material for sodium-ion batteries, ZnS nanospheres deliver high reversible sodium storage capacity, high Coulombic effi ciencies, and extended cycle life.