The effects of Ag content and dendrite spacing on the electrochemical behavior of Pb–Ag alloys for Pb-acid battery components

Abstract

The present study proposes correlations between the silver content and the dendrite arm spacing of two distinct Pb–Ag alloys (1 and 2.4 wt.% Ag) with their resulting electrochemical corrosion responses. Samples having a wide range of dendritic spacings were obtained using a water-cooled unidirectional solidification system. EIS, potentiodynamic polarization curves and an equivalent circuit were used to characterize the corrosion behavior of these samples in a 0.5 M H2SO4 solution at 25°C. It was found that both the Ag alloying and the scale of secondary dendritic arm, λ2, have important roles on the electrochemical corrosion behavior. The current density decreased with the increase in λ2. The increase in silver content provoked only a slightly improvement in the corrosion resistance and its addition to a Pb alloy should meticulously be analyzed considering the ratio anode/cathode areas. Although the addition of silver increases considerably the final cost of Pb–Ag alloys, these alloys can be used as alternative materials for the manufacture of lead-acid battery components.