(437g) A Promising Electrolyte of Ionic Liquids for Aluminium Deposition

A Promising Electrolyte of Ionic Liquids for Aluminium Deposition

Qian Wang^a, Bin Chen^a, Qinqin Zhang^a,b, Suojiang Zhang^a,*

^aBeijing Key Laboratory of Ionic Liquids Clean Process, Key Laboratory of Green Process and Engineering,

  State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences,

  Beijing 100190, P.R. China

^bCollege of Chemistry and Chemical Engineering, University of Chinese Academy of Sciences, Beijing 100049, P.R. China

^*Corresponding author. E-mail: sjzhang@home.ipe.ac.cn Tel.: +86 10 82627080

Ionic liquids (ILs) become the preferred electrolyte for aluminum electrodeposition due to their low melting point, negligible vapor pressure, high conductivity, and wide electrochemical window [1].  The research work on electrodeposition of aluminum from ILs began in 1951 [2], since then researchers conducted a series of studies [3-5], inwhich the types of ILs can be divided into four categories.  They are mixtures of anhydrous aluminium halides with alkylpyridinium halides, alkylimidazolium halides, alkylpyrrolidinium halides and aralkylammonium halides, respectively.  Usually, the anhydrous aluminium halide is anhydrous aluminium chloride (AlCl₃).

In this study, four typical ILs of the above four systems, 1- butyl -3- methylpyridinium chloride-AlCl₃, 1-butyl-3- methylimidazolium chloride-AlCl₃, 1-butyl-1-methylpyrrolidinium chloride-AlCl₃, and phenyltrimethylammonium chloride-AlCl₃, were chose using as the electrolyte for aluminium deposition.  Firstly, the physical properties of the four ILs were measured.  At room temperature, 1-butyl-3- methylimidazolium chloride-AlCl₃ has the highest conductivity and the lowest viscosity.  Meanwhile, they are similar in density.  Then aluminium coatings were prepared from them at the same current density, respectively.  By comparing the quality of the obtained coatings, it was found that compact and smooth aluminium coatings can be prepared from the IL formed by mixing 1-butyl-3- methylimidazolium chloride with AlCl₃ at 30℃.  But in the other three systems, only when the temperature is higher than 60℃, good quality aluminium coatings can be obtained.  Finally, the cyclic voltammetry of the four electrolytes was determined in a three-electrode cell at different temperature, also showing that the 1-butyl-3- methylimidazolium chloride-AlCl₃ has the best electrochemical property at a lower temperature.  All this proves that 1-butyl-3- methylimidazolium chloride-AlCl₃is a promising electrolyte for aluminium deposition.

References

[1] Brown L. Electroplating with non-aqueous solutions [J]. Trans. Inst. Met. Finish., 2010, 88,122-123.

[2] Hurley F H, Wier T P. The electrodeposition of aluminum from nonaqueous solution at room temperature [J]. J.Electrochem.Soc., 1951, 98, 207-212.

[3] Yue G, Zhang S, Zhu Y, et al. A promising method for electrodeposition of aluminium on stainless steel in ionic liquid [J]. AIChE J., 2009, 55, 783-796.

[4] Liu Q, Liu K, Han Q, et al. Study on electrodeposition of Al from trimethylphenylammonium chloride (TMPAC)-aluminum chloride (AlCl₃) ionic liquids + benzene. Chin. Surf. Eng.,   2010, 23, 34-39.

[5] Giridhar P, El Abedin S Zein, Endres F. Electrodeposition of aluminium from 1-butyl-1-methylpyrrolidinium chloride/AlCl₃ and mixtures with 1-ethyl-3-methylimidazolium chloride/AlCl₃ [J]. Electrochim. Acta, 2012, 70, 210-214.