Preparation And Supercapacitive Properties Of PbO₂-MnO₂ Electrodes By Electrodeposition

PbO₂-MnO₂ electrodes with three-dimensional porous structure were prepared using electrochemical codeposition methods through the manganese nitrate into the solution system.The optimum preparation technological condition and the concentration of manganese ion is 50mmol/L of the manganese ion concentration,30 mA/cm² of the current density,180 rpm of the stirring speed,60 min of the deposition time and the bath temperature keeps at 30℃.The morphology,structure and composition of PbO₂-MnO₂ electrodes were investigated by SEM,XRD,EDS and XPS.The results show that the content of manganese in the electrodes increases and the grain size decreases with the increase of manganese ions concentration in the bath.The content of manganese can reach 48.4 at%and the smallest grain size is 5.2nm when the manganese ion concentration is 50mmol/L.The surface area of PbO₂-MnO₂ electrode forming three-dimensional porous structure is about 2.5 times higher than the pure electrode.The influence of manganese ions on electrodeposition process of lead dioxide was studied by cyclic voltammetry（CV）,chronoamperometry（CA）and electrochemical impedance spectroscopy（EIS）.The results shows that manganese can inhibit the electrodeposition of lead dioxide.However,the nucleation model is not influenced by the addition of manganese ions and the electrodeposition process still fits instantaneous nucleation model with three-dimensional growth.The electrochemical capacitance properties of PbO₂-MnO₂ electrodes were determined by cyclic voltammetry（CV）,galvanostatic charge-discharge（GCD）and electrochemical impedance spectroscopy（EIS）.The results show that its capacitance is stored by the pseudocapacitance mechanism,and the specific capacitance decreases with the increasing of current density.The specific capacitance of PbO₂-MnO₂electrode is 379.91 F/g at 0.5 A/g.Obviously,the pure PbO₂ electrode exhibits much lower specific capacitance values than it,which is only 64.3 F/g.PbO₂-MnO₂electrodes possess the excellent supercapacitive performance,which are promising electrode materials for supercapacitors.The excellent specific capacitance can be attributed to the three-dimensional porous structure and the synergistic effect of lead dioxide with excellent conductivity and manganese dioxide with good specific capacitance.