The effect of Ca and Bi addition on the mechanical strength, corrosion resistance, and Rechargeability of Pb1.5Sn alloy for the positive grid of lead-acid batteries.

Lead-acid batteries need to evolve to keep up with the electrification of vehicles and not lose ground to other technologies. The grid designed using a lead alloy thus plays a very important role in the performance of the battery, as, in the course of the various cycles, this component undergoes a natural corrosion process at positive potential, while immersed in a sulfuric acid solution. The aim of this study is therefore to examine the effect of the addition of calcium and bismuth on the microstructure, mechanical behavior and corrosion resistance of the Pb1.5%Sn alloy, with a view to using this in the positive grid of lead-acid batteries. The alloys developed during this study were evaluated using optical microscopy and scanning electron microscopy. Mechanical properties were investigated using universal tensile and hardness tests. Electrochemical tests of cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy were carried out in a 5M sulfuric acid solution at 25 °C to simulate the behavior of the alloy when in operation. The composition of the corrosion products formed were subsequently characterized by morphological analysis using scanning electron microscopy and the composition was determined using energy dispersive X-ray spectroscopy and X-ray diffraction analysis. The results indicate that the Pb1.5Sn0.12Bi alloy presented better corrosion resistance characteristics than the Pb1.5Sn0.05Ca alloy, making it suitable for inclusion in the composition of the positive electrode of a lead-acid battery. Further investment is however required to compensate for the shortcomings in relation to the mechanical properties of the material.