Investigation of methoxypropionitrile as co-solvent for ethylene carbonate based electrolyte in supercapacitors. A safe and wide temperature range electrolyte

Abstract

The performances obtained with methoxypropionitrile/ethylene carbonate mixture based electrolytes were investigated in supercapacitor application. The incorporation of methoxypropionitrile allows a good compromise between electrochemical performances and safety issue to be exhibited in a wide temperature range. This improvement is associated with the decrease of electrolyte viscosity without compromising the salt solubility and dissociation. The highest conductivity values, 20mScm−1 at 30°C compared to 14mScm−1 in PC (propylene carbonate), were obtained with both 1M tetraethylammonium tetrafluoroborate (TEABF4) and spiro-(1,1′)-bipyrrolidium tetrafluoroborate (SBPBF4) salts. Bulk liquid state was conserved for these electrolytes in a wide temperature range. Then, interesting electrolyte conductivities were obtained at low temperature (5.2mScm−1 at −25°C) which is twice that of PC+TEABF4 1M electrolyte at the same conditions. Moreover, the capacitor performance of EC/MP based electrolyte is better than PC one at room temperature.