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

Effects of fluoroethylene carbonate (FEC)-induced solid-electrolyte-interface layers on carbon-based anode materials for potassium ion batteries were investigated, and a remarkable enhancement of cycling stabilities was achieved by adding small amount of FEC additive, 0.2 wt%, in a widely used carbonate-based electrolyte system. [Display omitted] •Effects of FEC additives on carbon-based anodes for potassium ion batteries were studied.•A carbonate-based electrolyte including FEC additives forms rigid inorganic SEI layers.•Excess FEC additive causes high film resistance (Rf), leading to poor reversible capacities.•0.2 wt% FEC induces well-balanced organic–inorganic hybrid SEI layers.•Stable cycling, high CE, and low self-discharge rate were achieved with 0.2 wt% FEC. 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.