Structure, microstructure and electrodeposition behaviours of aluminium from AlCl₃-EMIC and AlCl₃-BMIC ionic liquid electrolytes – a comparative study

Electrodeposition of aluminium on the copper substrate using two different chloroaluminate ionic liquid electrolytes such as AlCl3/1-Butyl-3-methylimidazolium chloride electrolyte (AlCl3-BMIC) and AlCl3/1-Ethyl-3-methylimidazolium chloride electrolyte (AlCl3-EMIC) were studied. Cyclic voltammetry studies reveal the aluminium deposition process follows two steps mechanism in AlCl3-EMIC electrolytes and in AlCl3-BMIC electrolytes, it follows single-step mechanism. The AlCl3-EMIC electrolytes permit wide deposition current density window than the AlCl3-BMIC electrolytes for aluminium deposition with good properties. The aluminium deposits obtained from AlCl3-EMIC electrolyte have better surface properties than the deposits obtained from AlCl3-BMIC electrolyte. Detailed comparative studies of deposits obtained from these two electrolytes with respect to deposition mechanism, deposition efficiency and deposition current density window were done. The deposit properties such as surface morphology, microstructure and crystal structures were also compared. From this study, we observed the AlCl3-EMIC electrolyte gives good quality deposits than AlCl3-BMIC electrolyte.