Highly amorphous PbO2 as an electrode in hybrid electrochemical capacitors

This paper presents a synthesis and characterizes highly amorphous lead dioxide and its use in hybrid electrochemical capacitor C/PbO₂. Highly amorphous lead dioxide with a small amount of β-PbO₂ was synthesized by galvanostatic deposition from acetate solution. The hybrid supercapacitor was constructed with PbO₂ as the positive electrode whereas activated carbon as the negative electrode. The morphology of materials was examined by scanning electron microscopy and their structure was characterized by means of an X-ray diffraction technique. The electrochemical performance of hybrid electrochemical capacitor with synthesized PbO₂ was studied by cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscopy. To indicate that the amorphous form of lead dioxide was predominant, results were compared to highly crystalline β-PbO₂. The hybrid electrochemical capacitor with synthesized material exhibits a much greater specific capacitance, higher specific energy and power than the highly crystalline one. The specific capacitance values obtained for the supercapacitor rose more than twice in favour of amorphous PbO₂. Also, long cycling did not influence any of the electrochemical properties of this hybrid electrochemical capacitor, which makes it an interesting energy storage device.