Highly Conductive Ionic Liquid Electrolytes for Potassium-Ion Batteries

Potassium-ion batteries (K-ion batteries; KIBs) are attractive as high-voltage, low-cost energy storage devices. Ionic liquids (ILs) potential candidates safe and high-performance electrolytes for large-scale Imidazolium-based ILs known to possess high ionic conductivities moderate electrochemical stabilities. In this study, we report the physicochemical properties of K[FSA]–[C2C1im][FSA] (FSA = bis(fluorosulfonyl)amide; C2C1im 1-ethyl-3-methylimidazolium) new KIBs. A phase diagram constructed from differential scanning calorimetry results indicates that melting point IL is below 273 K at compositions x(K[FSA]) 0–0.20 (x(K[FSA]) molar fraction K[FSA]). The viscosity, conductivity, density were measured 0–0.20. conductivity 0.20 10.1 mS cm–1 298 K, which comparable typical organic solvent-based KIB higher than other liquid stability M[FSA]–[C2C1im][FSA] (x(M[FSA]) 0.20; M Na, Li) was determined by cyclic voltammetry measurements. K-based exhibits widest window 5.19 V due negative redox K+/K couple. Thus, expected be a highly conductive electrolyte.