Effect of sodium dodecyl sulfate on the electrodeposited PbO₂ film on copper substrate for positive electrode of lead-acid battery

Significant internal impedance coupled with low electrochemical utilization of the cathode (PbO₂) in lead-acid batteries often cause poor discharge current density, leading to premature battery failure. To improve battery performance, lead dioxide (PbO₂) films were electrodeposited on a copper substrate from an alkaline lead nitrate solution with and without sodium dodecyl sulfate (SDS) additives. The films were characterized by coulombic efficiency and thickness measurements, scanning electron microscopy (SEM), and X-ray diffraction (XRD). Their electrochemical performance was assessed using cyclic voltammetry (CV) in 4.7 M H₂SO₄. The CV results indicated that charge-discharge current density, discharge density, and charge efficiency increase with cycle number. Films electrodeposited with SDS exhibited smaller grain sizes, higher porosity, and stronger substrate adherence, resulting in enhanced cycle endurance compared to films without SDS. The longest cycle life was observed for films deposited with 0.5 g/L SDS. During cycling, bulky crystallites converted into smaller grains with increased porosity, essential for enhanced battery performance. XRD analysis revealed that the films were primarily α-PbO₂, with SDS favoring increased β-PbO₂ content. Repeated cycles led to reduced crystallinity, with SDS aiding in minimizing amorphous PbO₂ formation. These findings suggest that PbO₂ electrodes deposited with 0.5 g/L SDS demonstrate improved cycling stability, making them highly suitable for lead-acid battery applications.