Effect of benzoquinone additives on the performance of symmetric carbon/carbon capacitors - electrochemical impedance study

This paper reports on the electrochemical performance of symmetric carbon/carbon electrochemical capacitors operating in aqueous electrolytic solutions with various benzoquinones as a source of pseudocapacitance. The benzoquinones have been introduced for the enhancement of capacitance values and the energy density in the final device. Three isomers, namely hydroquinone, catechol and resorcinol as electrolyte modifiers displayed different electrochemical activity in acidic electrolyte, affecting final electrochemical performance of the capacitors subjected to investigations. Furthermore, the paper demonstrates the electrochemical impedance spectroscopy as a powerful technique for electrochemical capacitor characterization and discusses the potential risk of the overestimation of the data recorded.