Nucleation of Lead Sulfate in Porous Lead‐Dioxide Electrodes

A one-dimensional mathematical model of a porous lead-dioxide electrode is described and used to investigate led-sulfate nucleation and growth during discharge. Derivation of a nucleation rate expression that is based on classical, heterogeneous nucleation theory is outlined. An electrochemical kinetic expression is derived based on a reaction mechanism involving elementary steps, and concentrated ternary electrolyte theory is used in formulating material-transport equations. Nucleation and electrochemical kinetic parameters are estimated by comparison of model results with experimental results available in the literature. The interplay of nucleation and growth kinetics of lead sulfate is responsible for the initial minimum in the voltage-time curve that is commonly observed during constant-current discharge.