LAUSR

Ionic liquids (ILs) are promising electrolytes for supercapacitors due to their wide electrochemical window. However, most ILs are viscous in nature and require diffusional and rotational transformations to access the pore space of common supercapacitor electrodes. In this study, novel anionic surfactant ILs (ASILs) are synthesized to lubricate the electrode surface to improve pore accessibility by IL ions. ASIL composition (0–10 wt%) and temperature (22–150 °C)-dependent capacitances, as a measure of pore accessibility and wettability, are determined by cyclic voltammetry. 10 wt% 1-butyl-1-methylpyrrolidinium docusate, [PYR14][AOT], in the base IL 1-propyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide, [PYR13][TFSI], exhibits the highest specific capacitance (202 F g−1 at 150 °C and 10 mV s−1), compared to [PYR13][TFSI] (160 F g−1). Electrochemical impedance spectroscopy measurements indicate resistive charging for ASIL/IL electrolyte compared to the base IL at 22 °C due to reduced conductivity—a consequence of larger non-polar domains. However, at elevated temperatures (> 100 °C), electrolyte resistance is circumvented as the viscosity is reduced. The wide voltage window of ILs and improved wettability by ASILs can be coupled to maximize energy storage capability of supercapacitors for high-temperature power applications.Graphical abstract