Fluorine-free Ionic Liquid Based on Thiocyanate Anion with Propylene Carbonate as Electrolytes for Supercapacitors: Effects of Concentration and Temperature

High performance supercapacitors were constructed using ionic liquid 1-ethyl-3-methylimidazolium thiocyanate(EmimSCN)-based electrolyte with chemically reduced graphene oxide(CRGO) as electrodes. Propylene carbonate(PC) was selected as the solvent due to its stable physical and electrochemical properties. Then, in-depth study of the concentration and temperature effects on the electrochemical properties of the EmimSCN/PC electrolyte was carried out. Electrochemical measurements revealed that 2.0 mol/L EmimSCN/PC electrolyte delivered good electrochemical performance(131 F/g of the specific capacity after 3000 cycles at room temperature). Moreover, the assembled supercapacitors exhibited good capacitive behavior at an extending temperature(397 F/g of the specific capacity after 3000 cycles at 50 degrees C), demonstrating that the EmimSCN/PC electrolyte is a promising candidate for safe high-power supercapacitors.