STUDY OF THE ELECTROCHEMICAL REDOX BEHAVIOUR OF THE LEAD AND ITS ALLOYS IN SULPHURIC ACID SOLUTIONS

摘要

Using the potentiodynamic method, the electrochemical redox behaviour of the Pb/PbSO_4 system on the lead alloys electrodes in aqueous H_2SO_4 solutions was studied. The potential sweep of the working electrode, within given potentials ranges (i.e. -1200mV to -800mV; +800mV to +1600mV and -1200mV to + 1600mV), was intended to simulate the processes taking place at the positive and negative plates of the lead/acid battery during charge/discharge cycling. The electrochemical redox behaviour of the Pb/PbO_(n(1.2))/PbSO_4 system on the lead and lead -alloy in aqueous H_2SO_4 solutions has been studied in the potential ranges mentioned above. The characteristics of the polarization curves (i.e., shape and height and potential range in which peaks appear), as well as the values of the kinetic parameters determined from such curves, enable conclusions to be drawn concerning the electrochemical characteristics of the Pb/PbO_(n(1.2))/PbSO_4 system. The behaviour of lead and lead alloys anodes during oxygen evolution in H_2SO_4 concentrated solutions has been studied by electrochemical impedance spectroscopy. A reaction model of anodic processes is presented, which quantitatively fits the experimental data.