Effects of temperature and current density on zinc electrodeposition from acidic sulfate electrolyte with [BMIM]HSO4 as additive

The effects of temperature and current density on cathodic current efficiency, specific energy consumption, and zinc deposit morphology during zinc electrodeposition from sulfate electrolyte in the presence of 1-butyl-3-methylimidazolium hydrogen sulfate ([BMIM]HSO4) as additive were investigated. The highest current efficiency (93.7%) and lowest specific energy consumption (2,486 kWh t(-1)) were achieved at 400 A m(-2) and 313 K with addition of 5 mg dm(-3) [BMIM]HSO4. In addition, the temperature dependence of some kinetic parameters for the zinc electrodeposition reaction was experimentally determined. Potentiodynamic polarization sweeps were carried out to obtain the expression for each parameter as a function of temperature. In the condition studied, the exchange current density depended on temperature as ln(i (0)) = -a/T + b and the charge transfer coefficient was constant. Moreover, the adsorption of the additive on cathodic surface obeyed the Langmuir adsorption isotherm. The associated thermodynamic parameters indicated the adsorption to be chemical.