Combined in-situ EC-AFM and CV measurement study on lead electrode for lead acid batteries

摘要

An Electrochemical Atomic Force Microscope (EC-AFM) was used to study the surface of a lead electrode in sulfuric acid electrolyte, when the reaction corresponding to what occurs at the negative electrode of a lead-acid battery took place. At first, the AFM observation was applied to the lead electrode during Cyclic-Voltammetry (CV) measurement as well, and was found to be useful to obtaining continuous in-situ AFM images of the surface morphology. These AFM images dynamically showed the surface morphology change depending on the oxidation and reduction of the lead electrode. From this observation result, it was visually confirmed that the quick deposition of lead sulfate crystals occurs after super-saturation phenomena at the oxidation peak on CV, and that the slow dissolving of the lead sulfate crystals occurs after the reduction peak. After that, AFM images of the lead sulfate morphology after oxidation were compared with those in a different potential sweeping rate and electrolyte concentration at CV. It was then clearly found that the crystal size becomes smaller when the potential sweeping rate is fast or the electrolyte concentration is high. We also confirmed that the difference in AFM images and SEM images that were observed on the same electrode after oxidation with potential sweeping was almost nothing.