Identification of self-discharge mechanisms of ionic liquid electrolyte based supercapacitor under high-temperature operation

Ionic liquids (ILs) are promising electrolytes for supercapacitors (SCs) aimed high-temperature applications, where increased ionic conductivity results in superior capacitive performance compared to room temperature (RT) performance. However, an also accelerates the self-discharge rate that adversely affects energy retention and restricts usage of SCs standalone applications. In this study, a detailed electrochemical investigation on behaviour carbon-based containing IL, 1-Ethyl-3-methylimidazolium acetate (EMIM Ac), has been carried out range RT - 60 °C, underlying mechanisms identified. The reveal at high voltage 1.5 V, is characterized by combination charge redistribution diffusion both °C. At diffusion-controlled mechanism dominates lower voltages over effect, while contribute similar extent. observed difference between °C explained terms decreased RC time constant (τRC) elevated temperature, same conclusions potentially applicable other IL-containing as well.