Electrochemical study of hydrocarbon-derived electrolytes for supercapacitors

In this paper, we evaluate the essential electrochemical properties-capacitive and resistive behaviors-of hydrocarbon-derived electrolytes for supercapacitor application using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The electrolytes were systematically prepared from three hydrocarbon-derived compounds, which have different molecular structures and functional groups, by treatment with high-concentration sulfuric acid (H₂SO₄) at room temperature. Two-electrode cells were assembled by sandwiching an electrolytecontaining glass wool separator with two active electrodes of activated carbon sheets. The dc electrical properties of the tested cells in terms of their capacitive behavior were investigated by CV, and in order to observe the frequency characteristics of the constructed cells, EIS was carried out. Compared with the tested cell with only high-concentration H ₂SO₄ as the electrolyte, the cell with the derived electrolytes exhibit a capacitance as high as 135 F/g with an improved overall internal resistance of 2.5ω. Through the use of a simple preparation method and lowcost precursors, hydrocarbon-derived electrolytes could potentially find large-scale and higher-rating supercapacitor applications.