FeS2 microspheres with an ether-based electrolyte for high-performance rechargeable lithium batteries

Abstract

Pyrite FeS₂ has been successfully applied in primary Li/FeS₂ batteries, but its poor cyclability in traditional carbonate-based electrolytes seriously hinders its application in rechargeable batteries. To overcome this issue, efforts have been made to focus on the modification of FeS₂. However, it is still difficult to improve the electrode performance especially for bare FeS₂. Herein, we report that changing carbonate-based electrolytes to selected ether-based lithium bis(trifluoromethanesulfonyl)imide and diglyme electrolytes greatly enhances the reversibility of the electrochemical reaction. FeS₂ microspheres with a high tap density of 2.2 g cm⁻³ show the stable discharge capacities of 680 mA h g⁻¹ at 100 mA g⁻¹ and 412 mA h g⁻¹ even at 6000 mA g⁻¹. Moreover, the capacity retention is 90% after 100 cycles at 1000 mA g⁻¹. The main reason for the long cycling is to inhibit the side reaction of the intermediate polysulfides with electrolytes.