Growth and Dissolution Kinetics of Lead Sulfate and Lead Dioxide Crystals in Positive Plates of Lead–Acid Batteries
Effective utilization of the positive active-material (PAM) is key to increasing lead–acid battery performance. The capacity of the lead-acid battery is limited by the supply of sulfuric acid solution into the pores of the PAM. If the concentration of the electrolyte can be maintained within the pores during the discharge process, then the PAM may be utilized more effectively and return a higher capacity. Low-utilization coefficients can be attributed to the formation of large lead sulfate (PbSO4) crystals during discharge, which are known to block the pores of the PAM on the surface and prevent further acid penetration into the inner parts of the plate. To mitigate pore blockage and increase the pore structure of the PAM, various paste additives have been investigated such as diatoms, inert fillers, fibres, and porous materials. This presentation focuses on the addition of porous polymethacrylate cross polymer (PMMA) microspheres into the PAM. The porous and hydrophilic nature of this additive enables the absorption of the sulfuric acid solution, which, in turn, could serve as an acid reservoir and prevent acid starvation inside the pores during discharge. In particular, the study elucidates the influence of the PMMA additive on PbSO4 to PbO2 transformation, crystallization, and growth kinetics during the charge–discharging reactions. Using 2-V laboratory test cells, the effects of the porous PMMA microspheres are observed in situ with electron microscopy and X-ray diffraction techniques.
PhD. Candidate, Missouri University of Science and Technology
Julian Kosacki is a PhD Candidate at the Missouri University of Science and Technology. He is currently collaborating with NorthStar Battery Company to undertake research on advanced lead–battery technologies that are operating in microgrid systems at the campus’s EcoVillage. Members of the University’s Microgrid Industrial Consortium aim to explore improvements in lead–acid batteries for storage of renewable energy source in communities of the future.