Influence of Sn addition on the corrosion resistance and recharge capacity of Pb-1, 5wt%Sn alloy for positive grids of lead acid batteries

ABSTRACT The present work aimed to evaluate the corrosion process of the Pb and Pb-1,5wt%Sn alloy under cycling conditions in sulfuric acid, in order to understand the influence of Sn on the corrosion resistance and recharge capacity for positives grids of lead-acid batteries. The study samples were prepared by casting process. The microstructure of the materials was evaluated by optical microscopy. Cyclic voltammetry tests for simulation of charge and discharge of positive electrode in accumulators were carried out in sulfuric acid (5M) in the potential range of 1.3 V to 2.2 V (vs SCE), totaling 400 cycles. The morphology and composition of the corrosion product deposits were analyzed by scanning electronic microscopy (SEM) and X-ray diffraction (XRD), respectively. Weight loss, electrochemical impedance spectroscopy (EIS) and SEM analysis were performed to evaluate the effect of corrosion process on the surface of the analyzed materials. The study showed that Sn addition promoted a doping effect on the formed corrosion deposits layers, increasing the charging efficiency of the accumulator and decreasing the weight loss by corrosion. The Pb1.5wt%Sn alloy showed to be more susceptible to the intergranular corrosion process and pitting corrosion in the grain compared to pure Pb.