A Corundum Membrane Ni/Ni2+ Reference Electrode for High-Temperature Fluoride Molten Salt

Abstract

Molten salts are widely employed as attractive electrolytes in electrolytic refining, extraction and separation of spent fuel, and electrochemical formation of metals and its alloys, etc. However, the high temperature and strong corrosiveness of fluorine molten salt make it difficult to select and establish a stable and reliable reference electrode. To meet this challenge, a new reference electrode for fluorine molten salt was conveniently fabricated by sealing the Ni/Ni2+(NiF2) couple in a commercial corundum tube whose closed end was ground into a membrane (ca. 0.1 mm in thickness) as ion membrane to facilitate ion conduction. The performances of Ni/NiF2 reference electrode were determined by various electrochemical techniques. The results showed that the Ni/NiF2 reference electrode had a good stability tested by CV for 50 h, and the deviation of the potential was 10 mV. The potential deviation of the Ni/NiF2 electrode prepared after different fabricated times and multiple cooling and melting could be controlled within 5 mV, which showed that Ni/NiF2 had a good reproducibility. Furthermore, Ni/NiF2 exhibited a good temperature reversibility and reusability. These findings indicated that the prepared Ni/NiF2 electrode could be a suitable reference electrode for fluoride molten salt.