Improving the Stability of Supercapacitors at High Voltages and High Temperatures by the Implementation of Ethyl Isopropyl Sulfone as Electrolyte Solvent

摘要

Two of the main weaknesses of modern electric double-layer capacitors arethe rather limited ranges of operating voltage and temperature in whichthese devices do not suffer from the occurrence of irreversible decompositionprocesses. These parameters are strongly interconnected and lowering theoperating voltage when increasing the temperature is unavoidable, so asto protect the electric double-layer capacitor from damage. With the aim tomaintain the operating voltage as high as possible at elevated temperatures,in this study, the application of ethyl isopropyl sulfone as an electrolytesolvent for electric double-layer capacitors is presented. It is shown thatethyl isopropyl sulfone-based electrolytes display excellent thermal andelectrochemical stability enabling high capacitance retention after floatingtests for 500 h at 60 and 80 ℃, e.g. 68 at 3.4 V at 60 ℃. A possible reasonfor the above-average stability is that decomposition products of ethylisopropyl sulfone can deposit on the electrode surface which may act as apassivation layer and prevent further degradation.