Electrodeposited PbO2 thin film as positive electrode in PbO2/AC hybrid capacitor

Lead dioxide (PbO2) thin films were prepared on Ti/SnO2 substrates by means of electrodeposition method. Galvanostatic technique was applied in PbO2 film formation process, and the effect of deposition current on morphology and crystalline form of the PbO2 thin films was studied by means of scanning electron microscopy (SEM) and X-ray diffraction (XRD). The energy storage capacity of the prepared PbO2 electrode was investigated by means of cyclic voltammetry (CV) and charge/discharge cycles, and a rough surface structure PbO2 film was selected as positive electrode in the construction of PbO2/AC hybrid capacitor in a 1.28 g cm−3 H2SO4 solution. The electrochemical performance was determined by charge/discharge tests and electrochemical impedance spectroscopy (EIS). The results showed that the PbO2/AC hybrid capacitor exhibited high capacitance, good cycling stability and long cycle life. In the voltage range of 1.8–0.8 V during discharge process, considering the weight of all components of the hybrid capacitor, including the two electrodes, current collectors, H2SO4 electrolyte and separator, the specific energy and power of the device were 11.7 Wh kg−1 and 22 W kg−1 at 0.75 mA cm−2, and 7.8 Wh kg−1 and 258 W kg−1 at 10 mA cm−2 discharge currents, respectively. The capacity retains 83% of its initial value after 3000 deep cycles at the 4 C rate of charge/discharge.