Redox behaviors of zirconium in molten LiCl-KCl eutectic salt based on the comproportionation reaction between Zr(0) and Zr(IV)

•The unique comproportionation reaction between Zr(0)/Zr(IV) is investigated.•The product of the comproportionation reaction is Zr(III) rather than Zr(II).•The redox mechanism of Zr is suggested based on experimental results.•The erroneous redox reactions of Zr in previous literatures are correctly interpreted.

The electrochemical behavior of Zr was investigated by a unique comproportionation reaction between Zr(0) and Zr(IV) in molten LiCl-KCl eutectic salt. Based on X-ray photoelectron spectroscopy and square wave voltammetry, the unknown Zr ion, which is the product of comproportionation reaction, was disclosed as Zr(III) instead of Zr(II). Additionally, the cyclic voltammogram of LiCl-KCl-ZrCl4 system showed a significant difference by changing the working electrode. In accordance with the experimental results, the expected reaction for the major redox peaks on cyclic voltammogram was suggested in comparison with other literatures.