Dissolution of zinc oxide in a protic ionic liquid with the 1-methylimidazolium cation and electrodeposition of zinc from ZnO/ionic liquid and ZnO/ionic liquid–water mixtures

• ZnO can be dissolved in a protic imidazolium ionic liquid at quite a high concentration.
• Zn2+ ion was stabilized by 1-methylimidazole, evidenced by FTIR and Raman spectra.
• High current density deposition of zinc can be achieved both in ionic liquid and in ionic liquid–water mixtures.
• A spongy-like porous zinc structure was obtained.

We show that zinc oxide can be dissolved in the protic ionic liquid 1-methylimidazolium trifluoromethylsulfonate, [MIm]TfO at quite a high concentration (~ 2.5 mol/L). FTIR and Raman spectra revealed the association of zinc ions with 1-methylimidazole. The ZnO/[MIm]TfO solutions and their mixtures with water were employed as electrolytes for the electrodeposition of zinc. High current density electrodeposition of zinc can be achieved in the employed electrolytes. Spongy-like zinc structures with a high porosity were obtained in ZnO/[MIm]TfO and the formation of Au1.2Zn8.8 alloy was observed. Compact and hexagonal zinc deposits were found in the presence of water. The present results show the potential of ionic liquids as electrolytes for rechargeable zinc–air batteries.