engleski

Three electrode electrochemical investigation of different salt/solvent electrolyte combinations in a symmetrical carbon/carbon double layer supercapacitor

To grasp a clear image of the processes inside a supercapacitor, their effect on cell performance and the contribution of both the positive and negative side, it is of great importance to perform simultaneous measurements on both sides using a three electrode setup. Therefore, such measurements were performed on a double-layer carbon/carbon supercapacitor assembled in a three-electrode sandwich cell design. Sixteen different combinations of salts and solvents were used to prepare the electrolytes – four salts (tetraethylammonium tetrafluoroborate, tetrabutylammonium tetrafluoroborate, tetraethylammonium hexafluorophospate and tetrabutylammonium hexafluorophospate) and four solvents (acetonitrile, dimethyl sulfoxide, dimethylformamide and propylene carbonate). Constant current charging/ discharging, cyclic voltammetry and electrochemical impedance spectroscopy techniques were employed for testing. As shown in our previous work[1] the impedance measurements are affected by asymmetries in the cell design and show predictable artefacts in single electrode measurements. Whole cell measurements show to be qualitatively and quantitatively comparable to the sum of the single electrode results which confirms the validity of the measurements. The results of DC measurements did not show sensitivity to cell design asymmetries and provide valuable insight to the applicability of certain solvent-salt combinations for their use as supercapacitor electrolytes. Simultaneous measurements of both the anode and cathode side allowed us to observe the differences in the performance of individual electrolyte combinations and their applicability in supercapacitors.

supercapacitors, measurement artefacts, electrochemical impedance spectroscopy

nije evidentirano