Evaluation of the Properties of an Electrolyte Based on Formamide and LiTFSI for Electrochemical Capacitors

The performance of electrical energy storage devices depend on the electrolyte properties. Concentrated electrolytes are promising for high-performance energy storage devices thanks to their inherent safety and low cost. We study here different concentrated solutions composed of LiTFSI as a salt (0.5, 1.0, 3.0, 4.0 and 4.5 M) and formamide as a solvent for electrochemical capacitor applications. These electrolytes exhibit appreciable ionic conductivity (2.3 to 8.2 mS cm−1), are favor of electrochemical properties of activated carbon-based EDLC. Electrochemical results reveal that, compared to usual electrolytes, high concentrated electrolytes exhibit long-term cyclability with significant capacitance up to 2000 cycles at an operating voltage of 2.2 V. Moreover, this study shows that low concentrated electrolytes highly corrode the Al current collector whereas the high concentrated electrolytes suppress the Al current collector corrosion process owing to the lack of free solvent (uncoordinated to a Li+ cation).