Long-Term Stability of Mullite and Magnesia-encased Ag|Ag + Reference Electrodes in Molten MgCl 2 -KCl-NaCl

• Published in: Journal of the Electrochemical Society Vol. 170; no. 5; p. 57505
• Main Authors: Choi, Suhee, Steppan, Jim, Simpson, Michael F.
• Format: Journal Article
• Language: English
• Published: United States The Electrochemical Society 08.05.2023
• ISSN: 0013-4651; 1945-7111
• DOI: 10.1149/1945-7111/acd35a

In this study, the stability of Ag|Ag + molten chloride reference electrodes was studied using mullite and magnesia tubes as reference electrode membrane materials in molten MgCl 2 -KCl-NaCl for continuous immersion up to 31 d. Two electrochemical methods were used to characterize the long-term performance of the reference electrodes at 500 °C in an inert atmosphere using a Mg rod as the working electrode: open circuit potential (OCP) and onset of Mg(II) reduction as measured by cyclic voltammetry (CV). There was only a 3% difference between the average OCP measured versus the mullite and MgO reference electrodes. Potential drift was higher for mullite (−1.34 mV d −1 ) than MgO (0.22 mV d −1 ). But both drift rates were very low compared to the OCP data standard deviation, indicating that no significant drift was measured for us to 31 d.