Determination of Pseudocapacitance Changes of Nickel Oxide NiO Electrode with the Use of Dynamic Electrochemical Impedance Spectroscopy

The electrochemical capacitors (ECs) are attractive energy storage devices which can be applied in many electronic products (e.g., cameras, laptops, cell phones) or hybrid electric vehicles (HEV). The energy storage in ECs is based on capacitive (the electrical double layer charging/discharging) and pseudocapacitive (additional charge provided by faradic reaction) phenomena. Considering the electrodes exhibiting pseudocapacitance, examination of their capacitance value is usually complicated, mainly because of its dependence on applied potential. This paper presents the results of evaluating the capacitance of the nickel oxide electrode material by the analysis of the impedance spectra obtained by Dynamic Electrochemical Impedance Spectroscopy (DEIS). The proposed solution allows to acquire the detailed information about capacitance changes as a function of applied potential. Another applied technique, i.e. Atomic Force Microscopy (AFM) revealed no significant changes of electrode topography during polarization.