Oxidation of Nickel in AlCl3-1-Butylpyridinium Chloride at Ambient Temperature

We have studied in detail the electrochemical reaction of nickel in several kinds of molar ratio-controlled molten salts consisting of AlCl 3 and 1-butylpyridinium chloride (BPC) at 40°C. We observed NiCl 2 as an oxidation product from nickel on the surface of the electrode in slightly acidic AlCl 3 /BPC salts with molar ratios of 1.05/1.0 and 1.1/1.0. However, in strongly acidic salt with the ratio of 1.5/1.0, NiCl 2 deposits on the electrode less than when in the above salts, and no NiCl 2 is observed in basic and neutral salts with the ratio of 1.0/1.0 or less AlCl 3 content. This suggests that [NiCl 4 ] 2− ions form as the oxidation of nickel in such neutral and basic AlCl 3 /BPC salts.