Electrochemical performance of electrochemical double layer capacitors containing pyrrolidinium and ammonium fluorosulfonyl imide in acetonitrile-based electrolytes

Abstract

In this study, we conducted a comprehensive analysis of the chemical-physical properties of electrolytes containing the ionic liquids N-propyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide [Pyr₁₃FSI] and N-trimethyl-N-propylammonium bis (fluorosulfonyl)imide [N₁₁₁₃FSI] dissolved in acetonitrile (ACN). We showed that these innovative electrolytes display favourable transport and thermal properties. When used as electrolytes in electrical double layer capacitors (EDLCs), they allow the realization of devices with excellent energy and power density values, which can be maintained over a wide temperature range. When charge-discharge cycles are carried out, the stability of EDLCs containing these alternative electrolytes is comparable to that of devices containing conventional electrolytes. However, during float tests, their stability is affected by the occurrence of anodic dissolution of the Al current collectors.