Room-Temperature Fluoride Shuttle Batteries Based on a Fluorohydrogenate Ionic Liquid Electrolyte

Fluoride shuttle batteries (FSBs) are attracting considerable interest as next-generation energy storage devices, owing to their superior energy density. We focused on fluorohydrogenate ionic liquids (FHILs) as new electrolytes for FSBs operating at room temperature, because they show much higher ionic conductivities compared with those of conventional electrolytes. In the present study, the charge–discharge behavior of CuF2 positive electrodes was investigated in the [C2C1im][(FH)2.3F] (C2C1im = 1-ethyl-3-methylimidazolium) FHIL at 298 K. The CuF2 electrode exhibited an initial discharge capacity of ca. 500 mAh (g-CuF2)−1, which is close to the theoretical capacity, 528 mAh (g-CuF2)−1.