Cesium carborane as an unconventional non-aqueous electrolyte salt for electrochemical capacitors

•Novel cesium carborane salt based non-aqueous electrolytes for electrochemical capacitors.•Cesium cation specific adsorption on micro-meso-porous carbon surface depends on the organic solvent used.•The so-called pore opening process (electrowetting) takes place during electrochemical capacitor system charge/discharge cycles, leading to the system recovery from starvation-like behavior in dilute electrolytes.

A novel electrolyte salt for non-aqueous electrochemical capacitors, cesium carborane, was electrochemically characterized in two organic solvent systems at different concentrations–acetonitrile and a 1:1 mixture of ethylene carbonate and dimethyl carbonate. It was found that Cs+ ion specific adsorption takes place, being dependent on the electrolyte concentration and on the solvent used. Stronger specific adsorption effect with partial charge transfer was observed from the acetonitrile based electrolytes, where the cesium salt has low solubility.