Molten salt processes were developed several decades ago as a promising technology for material processing and industrial process heat applications. This technology is still seen today as extremely suitable for thermal energy storage and power production. Liquid salts can indeed be considered legitimate candidates for several heat transfer applications thanks to favorable physical properties such as high boiling point, low vapor pressures, large specific heat, and large thermal conductivity.

In December 2015 a “Molten Salt Electrochemistry Short Course” was organized at University of Wisconsin Madison. The course was taught by Professor Digby MacDonald, a renowned expert in electrochemistry techniques for corrosion studies in aqueous environments. The course concentrated on the fundamentals of electrochemistry, with specific references to processes such as corrosion, electro-deposition, passivity and passivity breakdown, stress corrosion cracking, and corrosion fatigue. The course also included a discussion of the specialized techniques employed to study hydrogen in metals and carbon (graphite).

This paper will discuss the applicability of each of these electrochemistry techniques to molten fluoride salts and will provide an overview of the current status of these techniques in fluoride ionic liquids. The definition of a thermodynamically stable reference electrode (RE) has emerged as one of the critical points required to rigorously apply electrochemistry analytical techniques to fluoride salt systems. Therefore, this paper will review the fluoride molten salt RE designs developed in the 1960s and 1970s and in recent years. Additionally this paper will report designs and testing of the fluoride salt REs under development at University of Wisconsin -Madison.