Potential instabilities of lead-silver alloy anodes in acidic sulfate electrolytes

The kinetic behaviour of lead and lead-silver anodes, polarized under galvanostatic conditions in a H2SO4-ZnSO4-MnSO4 electrolyte, has been studied. Whereas the potential of the lead anode stabilizes during electrolysis, the potential of the lead-silver alloy anode oscillates between two limits after an induction time. Both silver on the anode surface and manganese in the electrolyte are required for the potential oscillations to appear. With increasing time the potential oscillations change in shape and period. From impedance data obtained earlier, at the beginning of, and during the potential oscillations, it is shown that the potential instabilities originate from electrode coverage by a silver salt adsorbate.