The electrochemical behaviour of lead dioxide electrodes

The electrochemistry of planar and porous lead dioxide electrodes has been investigated using the techniques: linear sweep voltammetry, potentiostatic pulse experiments and Faradaic (a.c.) impedance studies. The first two techniques were digitally controlled and the data were acquired at high speed and could be easily retrieved after storage. A morphological examination on the electrodes was also carried out using scanning electron microscopy. The electrochemical behaviour of flat lead in sulphuric acid at concentrations in excess of 5 mol dm-3 has been studied. Various solid lead alloys in different sulphuric acid concentrations were investigated together with porous PbO2 on different lead alloy supports. It was found that the acid concentration had a marked effect on the electrochemistry of the electrodes. The current transients obtained from potentiostatic step experiments with the porous PbO2 electrodes were nearly all of a complex nature and some attempt was made to match the data with established mathematical relationships for electracrystallisation processes. The alloys used were of industrial importance and they were lead-antimonyp lead-tin-calcium and lead-tin-bismuth-calcium. Also various automotive positive pastes were employed to form the porous PbO2 structure. A.C. impedance studies were carried out on the porous PbO2 electrodes. An analogue was found which described the discharge process of Pb02.