Different charge storage mechanisms at some carbon electrodes in redox active electrolyte revealed by electrochemical impedance spectroscopy

Different charge storage mechanisms at some carbon electrodes in redox active electrolyte are distinguished by electrochemical impedance spectroscopy technique. Significance of monitoring capacitive impedance contribution(s) in distinguishing battery-like and pseudocapacitive charge storage mechanisms is predicted by impedance modelling and verified experimentally. Experimental verification is made by comparison of capacitive impedance contributions in impedance spectra of graphite vs. glassy carbon electrodes. Impedance measurements are made at the same potential values in the supporting H2SO4 electrolyte and H2SO4/K4Fe(CN)6 redox active electrolyte, respectively.