Electrodeposition of bright Al and Al-Mn were carried out in AlCl3-1-ethyl-3-methyl-imidazolium chloride (AlCl3-EMIC) and MnCl2-AlCl3-EMIC ionic liquid with additives. The effects of the additive on the morphology
structure and brightness of the coatings were studied. The mechanism of brightening was discussed. The morphologies and structures of the coatings were characterized by SEM and XRD
respectively. The brightness of the coatings were characterized in the capability of reflecting images in the coatings. The results showed that ultra-bright Al and Al-Mn coatings were electrodeposited with the additives. The brightness of coating increased with the concentration of additive. The ultra-bright Al coating was nanocrystals with a preferred crystallographic orientation
while the ultra-bright Al-Mn coating was amorphous particles in nanometers. The brightening of coating is attributed to the grain refinement and preferred growth of the coating caused by the additive.