Ionic Liquid Modified Electrochemical Capacitor with Long‐Term Performance

Ionic liquids are used, for example, as corrosion inhibitors for metals, steel, and metal alloys. The method of preventing corrosion through the whole group of these kinds of compounds, called inhibitors, is to use them as additives to aggressive environments, including aqueous electrolytes. In this article, we present the inhibitive effect of imidazolium ionic liquids with 2,5‐dihydroxybenzenesulfonate anion on the corrosion of 316L stainless steel in neutral medium. In addition, we demonstrate that when the ionic liquid is used as an additive to the electrolyte solution (1 M Na2SO4) of a symmetric carbon/carbon electrochemical capacitor with 316L stainless‐steel current collectors, the capacitor lifetime is significantly extended. The ionic‐liquid additive inhibits corrosion of the current collector surface and, in effect, prevents activated carbon porous space from being blocked by corrosion products. The impact of imidazolium ionic liquids with a 2,5‐dihydroxybenzenesulfonate anion on the corrosion of 316L stainless steel in neutral medium is studied. The use of the ionic‐liquid additive in the aqueous electrolyte solution (1 M Na2SO4) of an electrochemical capacitor inhibits corrosion of the current collectors, thus extending the lifetime of the cell.