a novel room temperature organosilicon ionic liquid (sin1il) was synthesized and its chemical structure and electrochemical window were characterized. the ionic conductivity of sin1il/propylene carbonate (pc)/acetonitrile (an) solution was 19.6 ms.cm(-1), comparable with the commercial electrolytes currently used in supercapacitors. the electrochemical performance of the cells using activated carbon as electrodes and sin1il-based formula with pc/an as electrolytes was systematically evaluated. sin1il/pc electrolyte exhibited superior rate capability and lower impedance compared to a conventional electrolyte (tetraethylammonium tetrafluoroborate (et4nbf4)/pc). upon applying a working voltage of 2.7 v, the sin1il/pc cell had a specific capacitance of 108 f.g(-1) at a current density of 1000 ma.g(-1).