Effects of fluoroethylene carbonate-induced solid-electrolyte-interface layers on carbon-based anode materials for potassium ion batteries

Abstract Potassium ion batteries (PIBs) are characterized by poor cycling stabilities and insufficient Coulombic efficiencies (CEs) due to the employment of conventional carbonate-based electrolyte systems that are normally used in lithium ion batteries. In this study, we investigated the effects of fluoroethylene carbonate (FEC)-induced solid-electrolyte-interface (SEI) layers on carbon-based anode materials for PIBs and achieved a remarkable enhancement of cycling performance by adding a small amount of FEC (0.2 wt.%) in a carbonate-based electrolyte system. The 0.2 wt.% FEC additive induced the formation of well-balanced organic-inorganic hybrid SEI layers, which effectively blocked additional electrolyte decomposition in consecutive discharge/charge cycles, causing a significant enhancement of CE and capacity retention. In addition, the FEC additive reduced the self-discharge rate from 2.2 to 1.5 mV h-1, demonstrating its beneficial effect on cycling stabilities.