Influence of acidic ionic liquids as an electrolyte additive on the electrochemical and corrosion behaviors of lead-acid battery

The aim of this study is to introduce the application of some acidic ionic liquids (ILs) as an electrolyte additive in lead-acid batteries. A family of alkylammonium hydrogen sulfate ILs, which are different in the number of alkyl chain, is investigated with the aim to compare their effects on the electrochemical behavior of Pb-Sb-Sn alloy in sulfuric acid solution. The hydrogen and oxygen gas evolution potential and anodic layer characteristics were investigated employing cyclic and linear sweep voltammetric methods. The morphological changes of the PbSO4 layer that formed on the electrode surface were confirmed using scanning electron microscopy. Also, potentiodynamic polarization curves, electrochemical impedance spectroscopy, and an equivalent circuit analysis were used to evaluate the corrosion behaviors of the Pb-Sb-Sn alloy in the presence of ILs. The obtained results indicate that hydrogen and oxygen evolution overpotential of lead-antimony-tin alloy increases in the solution containing IL and mainly depends on the number of alkyl chain in alkylammonium cation. It is clearly observed that the morphology of PbSO4 layer changes under the influence of ILs. The corrosion studies show an increase in corrosion resistance of lead alloy in the presence of some ILs. Also, the electrochemical effects of ILs in conversion of PbSO4 to PbO2 and vice versa were investigated by carbon-PbO paste electrode. Cyclic voltammogram of carbon-PbO electrode shows that in the presence of ILs, oxidation and reduction peak currents increase, while reversibility decreases.