The components of electrolytes play an important role in determining the properties of supercapacitors. Different electrolytes have their superiority and disadvantages. Aqueous electrolyte is one of the electrolytes used in supercapacitors, but it is limited in industrialization because of its narrow voltage window and low energy density. The addition of organic solvents could enhance the performance of supercapacitors, which has gained more and more attention in this research direction. In this work, 6 mol/L KOH solution was used as the electrolyte, and the activated carbon with high specific surface area was used as electrode material. The effects of organic additives on the electrochemical performance and energy density of supercapacitors in aqueous electrolytes were investigated. The electrochemical properties of the supercapacitor were researched after adding different kinds of organic additives in the aqueous electrolyte. The results showed that the polarization phenomenon of the system can be significantly suppressed due to the addition of appropriate organic additives, the operating voltage window and energy density of the supercapacitor were improved. After 10vol% isopropanol was added to the aqueous electrolyte, the wettability between the electrode material and the electrolyte was greatly improved, and the specific capacity increased from 79.3 F/g to 113.2 F/g. Adding 20vol% isopropanol, the working voltage window of the system increased from ?0.8~0 V to ?0.8~0.5 V, the energy density of the supercapacitor reached 19.4 Wh/kg, the charge transfer resistance of the system was significantly reduced, the specific capacity decreased by 13.9% at 10 A/g than it was at 0.5 A/g while the specific capacity decreased by 30.3% without additives. However, when 30vol% isopropanol was added, since the ion transfer at the viscous electrolyte was limited, the conductivity was greatly lowered, resulting in rapid decay of the specific capacitance.
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