A MgMn₂O₄-Based Solid State Reference Electrode for High-Temperature Molten Salts

The development of reliable reference electrodes is critical for advancing electrochemical studies in high-temperature molten salts. In this work, the MgMn 2 O 4 /Mg 2 MnO 4 redox couple is utilized as a solid-state reference electrode in the ternary molten salt system MgCl 2 -NaCl-KCl. The electrochemical behavior of the MgMn 2 O 4 /Mg 2 MnO 4 redox couple was evaluated via cyclic voltammetry and chronopotentiometry, which revealed a reversible insertion and extraction of Mg in MgMn 2 O 4 . The MgMn 2 O 4 electrode displayed a stable value for 100 h when tested by monitoring the open circuit potential. The electrochemical behavior of Sb 2 O 3 was studied in MgCl 2 -NaCl-KCl to demonstrate the practical utility of the electrode. Cyclic voltammetry measurements, chronoamperometry, and powder X-ray diffraction analysis confirmed the complete reduction of Sb 2 O 3 to Sb. These findings show that the MgMn 2 O 4 /Mg 2 MnO 4 system is a promising candidate for stable and reproducible reference electrode for applications in high-temperature molten salt systems.