Preparation and performances of room molten salt as electrolyte in carbon-carbon capacitor based on LiPF6 and trifluoroacetamide

Abstract

A novel room molten salt with an eutectic temperature of about -62°C is prepared using LiPF6 and trifluoroacetamide as precursors. And then its performances are evaluated in carbon-carbon electrochemical double layer capacitor (EDLC) as electrolyte. The thermal properties of the complex electrolyte with different molar ratios are characterized and then the liquid-solid phase diagram is presented by using differential scanning calorimeter (DSC) and Fourier transform infrared spectroscopy (FTIR). The hydrogen bonding interaction between LiPF6 and trifluoroacetamide molecules is attributed to the formation of the as-prepared molten salt. In addition, the results of cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and conductance tests show that the as-prepared LiPF6/trifluoroacetamide electrolyte has a maximum conductance at room temperature, i. e. 1.30 mS/cm, a stable electrochemical window of ca. 5.6 V, an applicable temperature of more than 60°C, suggesting it is a promising electrolyte candidate for carbon-carbon EDLCs.