Physicochemical identity and charge storage properties of battery-type nickel oxide material and its composites with activated carbon

• A low temperature synthesis results in unusual capacitive behavior of nickel oxide.
• The capacitive properties are evaluated from two and three-electrode measurements.
• Activated carbon additive leads to approximately twofold increase in capacity of NiO-based symmetric cell.
• Also, the practical voltage window is broadened from 0.6V to 1V.
• The cell performance is improved in terms of energy and power densities.

The structural properties of annealed nickel oxide and its composites with activated carbon (synthesized via simple precipitation methods) have been addressed using X-ray diffraction, X-ray photoelectron spectroscopy, nitrogen adsorption/desorption method and scanning electron microscopy. The charge storage properties of materials have also been investigated in three- and two-electrode configurations by means of cyclic voltammetry and galvanostatic charging/discharging in alkaline media. The results are consistent with the view that, depending on a method of preparation, the resulting nickel oxide films may exhibit redox characteristics different from that typically observed for nickel oxide-based materials. It is demonstrated that faradaic-type (redox) reactions, that are typical for battery-like materials, contribute predominantly to the high electrode capacity of 257C g−1 (at 0.1 A g−1). By combining nickel oxide with a capacitive material such as activated carbon within the two-electrode symmetric cell, systems with increased charge-storage capabilities have been obtained. The fact, that the voltage window of nickel oxide-based cell has been broadened positively from 0.6 V to 1 V upon introduction of activated carbon, has also resulted in the increase of the cell’s energy and power densities as well.