Effect of Sn on the electrochemical corrosion behavior of Pb-Ca grid and influence on lead-acid battery performance

摘要

Lead antimony alloys lead to water loss in lead-acid battery applications and influence of battery performance. Nowadays lead-calcium alloys have replaced lead antimony alloys for positive grids of lead-acid batteries. Lead-tin alloys have good protective effect on capacity loss in deep discharge conditions. Amount of tin is important, increasing tin lead to increase the corrosion resistance, mechanical properties and grain size of lead–calcium–tin alloys. Growth of positive battery grids related with localized intergranular corrosion and creep along grain boundaries. Furthermore, the grain boundaries become smooth as the tin amount increased. Dependent on tin level decrease of oxidation current and weight loss of alloys due to corrosion and decrease of oxygen evolution. According to decreasing oxygen evolution affected battery self discharge performance.Corrosion of positive electrodes is the main factor in the life of battery. The aim of the present study is to examine electrochemical behavior and mechanical properties of Pb alloys with adding different Sn level. Pb-0.06%Ca-0.8%Sn and Pb-0.06%Ca-1.3%Sn alloys corrosion and oxygen evolution behavior were investigated by Tafel Extrapolation and Linear Sweep Voltametry (LSV) electrochemical techniques. The electrochemical tests were performed in 5M H_2S_O4 solutions at 25℃. All polarization experiments were performed using Gamry reference 3000 potentiostat/galvanostat corrosion measurement system and Hg/Hg_2SO_4 reference electrode. Grid corrosion test was performed using Gamry 3000 Potentiostat/Galvanostat with 30K Booster at 75℃ for evaluate weight loss and growth performance of alloys. Both Tafel Extrapolation and weight loss tests were demonstrated Pb-0.06%Ca-1.3%Sn alloy corrosion resistance is better. Otherwise, LSV result shows that oxygen evolution rate enhanced by decreasing tin level. Batteries were produced with using %0.8Sn and %1.3Sn alloy grids and Battery corrosion tests were performed at the end of present study. Grid corrosion test results promoted electrochemical tests. Decreasing tin level increased weight loss of grids and decreased corrosion resistance. Battery life that is produced with %0.8Sn grid is less than %1.3Sn.