Electrochemical Performance of Layered FeSe for Sodium Ion Batteries Using Ether-Based Solvents

We have evaluated layered FeSe as the anode in sodium ion-batteries using an ether-based electrolyte. The maximum first reversible capacity and efficiency are 294 mAh g(-1) and 87.2%, respectively. From XRD analysis, intercalation of Na ions between the selenide double layers of the layered FeSe occurred in the early stages of the first charging, which was followed by the formation of an amorphous Na-Se structure. Nevertheless, FeSe demonstrated good cycle performance and rate capability, with a discharge capacity retention ratio of 90% after 100 cycles and 75% at a current rate of 1.0 A g(-1) (similar to 3C). Overall, the results presented herein suggest that FeSe has potential to function as the anode in sodium ion batteries. (c) The Author(s) 2018. Published by ECS.