Determination of Kinetic Properties of Ni(II) Ions in Molten LiF-NaF-KF via Voltammetry

Smith, Nathan D.; Lombardo, Stephen J.; Shang, Shun‐Li; Liu, Zhe; Kim, Hojung

doi:10.1149/1945-7111/acd6c1

Cited by 2 publications

(3 citation statements)

References 30 publications

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“…Figure 5b illustrates the occurrence of Cr/Cr(II)/Cr (III) redox reactions within the potential window of +0.1 V to +1.0 V K+/K , and Ni/Ni(II) redox reactions in the range of +1.50 to +3.00 V K+/K . 47,56 It is noted that possible oxidation peaks are visible observed in vicinity to the Ni/Ni(II) peaks. This may be attributed to the polycrystalline nature of the Pt wire and the possible formation of Ni-Cr-F complex species, which has yet to be investigated in this salt environment.…”

Section: Resultsmentioning

confidence: 99%

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Morphological Evolution and Dealloying During Corrosion of Ni20Cr (wt.%) in Molten FLiNaK Salts

Chan,

Romanovskaia,

Mills

et al. 2024

J. Electrochem. Soc.

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In this work, the dealloying corrosion behavior of the FCC Ni20Cr (wt.%) in molten LiF-NaF-KF (FLiNaK) salts at 600 °C under varying applied potentials was investigated. Using in-operando electrochemical techniques and a multi-modal suite of characterization methods, we connect electrochemical potential, thermodynamic stability, and electro-dissolution kinetics to the corrosion morphologies. Notably, under certain potential regimes, a micro-scale bicontinuous structure, characterized by a network of interconnected ligaments and pores with the composition of the more noble (MN) element, becomes prominent. At other potentials both MN and less noble (LN) elements dealloy but at different rates. The dealloying process consists of bulk and grain boundary diffusion of Cr to the metal/salt interface, interphase Cr oxidation, accompanied by surface diffusion of Ni to interconnected ligaments. This process is predominately controlled by charge transfer, resulting in the formation of Cr(II) and Cr(III) species at a constant rate of attack for a period of 10,000 seconds. At higher potentials, the bicontinuous porous structure undergoes further surface coarsening. Concurrently, Cr(II), Cr(III), and Ni(II) begin to dissolve, with the dissolution of Ni occurring at a significantly slower rate. When solid state transport of Cr is exceeded by the interfacial rates, dealloying depths are limited.

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Section: Resultsmentioning

confidence: 99%

“…1a. For a more in-depth elaboration on the kinetic properties of NiF 2 or Ni(II) in FLiNaK, readers are referred to a recent study by Smith et al 47 These thermodynamic redox potentials can guide understanding of E-log(i) corrosion behavior.…”

Section: Resultsmentioning

confidence: 99%

Morphological Evolution and Dealloying During Corrosion of Ni20Cr (wt.%) in Molten FLiNaK Salts

Chan,

Romanovskaia,

Mills

et al. 2024

J. Electrochem. Soc.

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“…In some studies, the cylindrical working electrode is approximately regarded as a plate electrode, and the diffusion coefficient of the study object is calculated using Cottrell equation. [29][30][31][32] However, in this experiment, CA experiment and Cottrell equation were not used to calculate the diffusion coefficient. It is only necessary to obtain the limiting diffusion current through the CA experiment to calculate the diffusion layer thickness.…”

Section: Theoretical Analysismentioning

confidence: 99%

Mass Transfer Process by Diffusion of RE(III) (RE=La, Pr) in Eutectic LiCl-KCl Salt

Wei,

Li,

Cai

et al. 2024

J. Electrochem. Soc.

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Mass transfer is an important link in the entire electrode process. To investigate mass transfer process by diffusion of trivalent rare Earth ions in molten LiCl-KCl system, the electroreduction mechanism, mass transfer kinetics and diffusion layer thicknesses of RE(III) (RE = La and Pr) were studied by a series of electrochemical methods. It was found that RE(III) underwent one-step reduction reaction with the exchange of 3-electron and reversible processes. The diffusion coefficients (D) of RE(III) and limiting current densities (j l ) for RE(III)/RE pair were measured at different temperatures and concentrations by cyclic voltammetry and chronoamperometry, respectively. Based on the results of D and j l , the diffusion layer thickness (δ) of RE(III) was calculated using the simplified Nernst-Planck formula. Furthermore, the impacts of temperature and concentration on δ were explored. The results indicated that as the temperature declined and ions concentration increased, δ decreased. Meanwhile, the relationships between δ and temperature and concentration were also obtained.

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Determination of Kinetic Properties of Ni(II) Ions in Molten LiF-NaF-KF via Voltammetry

Cited by 2 publications

References 30 publications

Morphological Evolution and Dealloying During Corrosion of Ni20Cr (wt.%) in Molten FLiNaK Salts

Morphological Evolution and Dealloying During Corrosion of Ni20Cr (wt.%) in Molten FLiNaK Salts

Mass Transfer Process by Diffusion of RE(III) (RE=La, Pr) in Eutectic LiCl-KCl Salt

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