High voltage electrochemical capacitors operating at elevated temperature based on 1,1-dimethylpyrrolidinium tetrafluoroborate

In this manuscript, we report an investigation about the application of 1,1-dimethylpyrrolidinium tetrafluoroborate (Pyr11BF4) as conducting salt for electric double-layer capacitors (EDLCs). Utilizing this non-conventional salt is possible to realize highly conductive acetonitrile (ACN) based electrolytes. We showed that the use of the electrolyte 2 M Pyr11BF4 in ACN makes possible the realization of high perfomance EDLC operating at 3.4 V, and displaying excellent stability (88% capacitance retention after 500 h floating at 3.4 V). Additionally, EDLCs containing this alternative electrolyte outperforms the state-of-the-art devices also at increased temperature (91% capacitance retention after 500 h floating at 3.0 and 60 °C). Taking advantage of the postmortem GC–MS measuements, we showed that the higher performance possible with this novel electrolyte is associated to the high electrochemical and thermal stability of Pyr11BF4.