In situ analysis of electrochemical reactions at a lead surface in sulfuric acid solution

An Atomic Force Microscope (AFM) was used to analyze the surface of a lead plate when the reaction corresponding to what occurs at the negative electr ode of a lead acid battery, Pb + SO42- reversible arrow PbSO4 + 2e, took pl ace. At the beginning, when the lead plate, on the surface of which lead ox ide already existed, was in contact with sulfuric acid, lead sulfate crysta ls were formed and gradually grew with time without applying any potential. In situ AFM observation of the formation and the growth of lead sulfate at the potential corresponding to the discharge reaction was attempted. And i t was possible along with the reduction of the lead sulfate, which formed i n discharging process. The results also showed that the chemically formed l ead sulfate crystals were clearly different in appearance from the electroc hemically formed ones. These results were also applied to a study of the me chanism of the sulfation process that often occurs in the active material o f the negative electrode of a lead acid battery. (C) 2000 Elsevier Science S.A. All rights reserved.