Evaluation of the effect of additive group five elements on the properties of Pb-Ca-Sn-Al alloy as the positive grid for lead-acid batteries

As an important part of lead-acid batteries, the grid is mainly used to support active substances and conduct current. Currently, Pb-Ca-Sn-Al alloys are widely used as materials for valve-regulated lead-acid battery grids. The influence of bismuth, barium, strontium, and germanium as alloying additives on the physical and electrochemical behaviors of Pb-Ca-Sn-Al alloys was studied by the methods of metallographic, cyclic voltammetry, linear scanning voltammetry, AC impedance, and scanning electron microscopy. The results show that the addition of Bi and Ba can increase the grain size of the alloy and reduce the intergranular corrosion and corrosion rate of Pb-Ca-Sn-Al alloy. Furthermore, the addition of Bi and Ba could inhibit the growth of Pb (II) and PbO₂ in corrosion layer and improve the corrosion resistance of the alloy. Significantly, Bi and Ba will reduce the oxygen evolution overpotential of the alloy by about 30 mV, which will play important roles on the maintenance-free performance of lead-acid batteries. Both Sr and Ge promote the grain corrosion and intergranular corrosion of the alloy, reducing the corrosion resistance of the alloy. Therefore, improving the performance and corrosion life of the grid by using additives is an important approach to further extending the service life of lead-acid batteries.