文献类型：期刊文献

英文题名：Electrochemical behavior of Fe(Ⅲ) and mechanism of cathode passivation induced by Fe(Ⅲ) in MgCl?-KCl molten salt

作者：Liu, Zhuangzhuang[1]; Yang, Xiaobo[3]; Li, Shengting[4]; Lu, Guimin[1]; Sun, Ze[1,2,3]

机构：[1] National Engineering Research Center for Integrated Utilization of Salt Lake Resource, School of Chemical Engineering, East China University of Science and Technology, Shanghai, China; [2] Salt Lake Chemical Engineering Research Complex, Qinghai University, Xi’ning, 810016, China; [3] School of Chemistry and Materials Science, Qinghai Minzu University, Xi’ning, 810007, China; [4] Qinghai Yanhu Industry Co., Ltd., Golmud, 816099, China

年份：2026

外文期刊名：Ionics

收录：EI(收录号：20262520956960)

语种：英文

外文关键词：Cathodes - Chlorine compounds - Chlorite minerals - Electrolysis - Electrolytic reduction - Iron deposits - Magnesium - Molar ratio - Molten materials - Passivation - Potassium compounds - Salt deposits

摘要：Iron impurities are among the most detrimental impurities in magnesium electrolysis because they can promote cathode passivation, reduce current efficiency, and contribute to Mg loss. This study systematically investigated the electrochemical reduction of Fe(Ⅲ) and the corresponding cathode passivation mechanism in an anhydrous carnallite melt composed of MgCl? and KCl with a molar ratio of 1:1 at 973K. Based on cyclic voltammetry (CV), square wave voltammetry (SWV), chronoamperometry (CA), chronopotentiometry (CP), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS), the results show that Fe(Ⅲ) reduction is a single-step, diffusion-controlled, quasi-reversible process. Current reversal chronopotentiometry (CR-CP) measurements based on representative curves suggested a decrease in apparent current efficiency from 92.5% to 79.1% after 10min of electrolysis. Morphological and electrochemical analyses further suggest the underlying passivation mechanism. During the initial stage of electrolysis, Fe(Ⅲ) is preferentially reduced and deposited on the cathode surface as a porous, sponge-like structure. The newly formed porous Fe deposits may adsorb MgO-containing species from the molten salt, suggesting the possible presence of an Fe/Mg/O-rich passivation layer on the cathode surface. Such a surface layer may reduce the wettability of the cathode toward liquid Mg and hinder the spreading and coalescence of Mg droplets, thereby promoting the deposition of Mg as fine, discrete, caviar-like particles with diameters below 1mm. This process may contribute to Mg loss and the decrease in current efficiency during electrolysis. These findings provide fundamental insight into the role of Fe(Ⅲ) in cathode passivation during magnesium electrolysis. ? The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2026.