(153a) Challenges in Selecting Appropriate Working and Reference Electrodes for High-Temperature Molten Salt Systems

Depending on which molten salt (e.g., chloride, fluoride, iodide) is investigated, different working and reference electrode materials can be selected based on the chemical and thermal stability of the electrochemical cell components. In this talk, I will discuss the electrode materials and challenges observed in a spectro-electrochemical setup installed inside a glovebox, and how these challenges were overcome, specifically for the chloride and iodide molten salts.

For molten chlorides, the fundamental interactions between neodymium chloride (NdCl₃) and Nd metal in lithium chloride-potassium chloride eutectic salt were investigated at 773 K. The electrochemical transitions Nd^2+,3+/Nd(s) were evaluated using an inert W electrode with cyclic voltammetry and chronoamperometry techniques, coupled with in-situ UV-Vis spectroscopy to characterize the kinetic pathways of this disproportionation reaction (eq. 1).

Nd(s) + NdCl₃ = NdCl₂ (1)

Along with this study, the spectro-electrochemistry of Chromium Chlorides and Molybdenum Chloride salts will be evaluated, along with its challenges of utilizing different working electrode materials. In the case of molten iodides, I will discuss the challenges related to working electrode selectivity and present spectro-electrochemical results obtained from cyclic voltammetry measurements conducted at 673 K.