Electrochemical Impedance Spectroscopy and Cyclic Voltammetry Methods for Monitoring SmCl3 Concentration in Molten Eutectic LiCl-KCl

  • Shaltry, Michael R. (Idaho National Laboratory) ;
  • Allahar, Kerry N. (Boise State Univ.) ;
  • Butt, Darryl P. (Univ. of Utah, Department of Materials Science & Engineering) ;
  • Simpson, Michael F. (Univ. of Utah, Department of Materials Science & Engineering) ;
  • Phongikaroon, Supathorn (Virginia Commonwealth Univ.)
  • Received : 2019.11.05
  • Accepted : 2020.03.10
  • Published : 2020.03.30


Molten salt solutions consisting of eutectic LiCl-KCl and concentrations of samarium chloride (0.5 to 3.0 wt%) at 500℃ were analyzed using both cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The CV technique gave the average diffusion coefficient for Sm3+ over the concentration range. Equipped with Sm3+ diffusion coefficient, the Randles-Sevcik equation predicted Sm3+ concentration values that agree with the given experimental values. From CV measurements; the anodic, cathodic, and half-peak potentials were identified and subsequently used as a parameter to acquire EIS spectra. A six-element Voigt model was used to model the EIS data in terms of resistance-time constant pairs. The lowest resistances were observed at the half-peak potential with the associated resistance-time constant pairs characterizing the reversible reaction between Sm3+ and Sm2+. By extrapolation, the Voigt model estimated the polarization resistance and established a polarization resistance-concentration relationship.


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