Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “KCl”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Synthesis of americium trichloride via chlorination of americium oxide using zirconium tetrachloride in LiCl-KCl molten salt

To better inform electrorefining operations of used nuclear fuel, a fundamental understanding of the electrochemical properties of each actinide in the molten salt electrolyte is needed. Access to actinide chlorides is thus required to support measurement of these properties. In this work, we synthesized americium trichloride through a novel pathway comprising chlorination of Am2O3 with ZrCl4 in a LiCl-KCl molten salt at 500 degrees C. The formation of AmCl3 was confirmed by cyclic voltammetry and gamma spectroscopy. This chlorination method does not produce mixed hazardous-radioactive waste and the byproduct, ZrO2, is not electrochemically active and does not affect the actinide electrodeposition reaction.

actinide chloride synthesis↗
DOE OSTI2023

Time dependent chlorination of CeO 2 , La 2 O 3 and Nd 2 O 3 by ZrCl 4 dissolved in eutectic LiCl–KCl

Partial chlorination of CeO 2 , La 2 O 3 , and Nd 2 O 3 was achieved using ZrCl 4 dissolved in molten LiCl-KCl at 450°C over a period of 4-5 hr. ZrCl 4 was pre-volatilized into an argon stream to maintain a constant vapor pressure for equilibration with the salt. This approach was effective at maintaining the ZrCl 4 concentration at the solubility limit of 1.3 mol% in the molten salt throughout the duration of two of the chlorination experiments and within about 60% of the solubility limit in the third experiment. Based on the analysis of salt samples, fractional conversion after four hours of reaction for CeO 2 , and five hours for La 2 O 3 , and Nd 2 O 3 were calculated to be 0.97, 0.28, and 0.65 respectively. Assuming a shrinking core diffusion-limited model, the diffusivity of ZrCl 4 through the hypothesized ZrO 2 layer was calculated for the chlorination of CeO 2 , La 2 O 3 , and Nd 2 O 3 were 1.76 x 10 -10 cm 2 /sec, 7.85 x 10 -12 cm 2 /sec, and 7.42 x 10 -12 cm 2 /sec, respectively. Given the extremely low values calculated for diffusivity, it was concluded that the process is chemical reaction rate limited and that a complete reaction of each rare earth oxide could be achieved. Furthermore, a chemically controlled shrinking core model was shown to also fit the experimental data closely.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2021

Effect of excess Mg to control corrosion in molten MgCl 2 and KCl eutectic salt mixture

Structural alloys may experience corrosion when exposed to molten chloride salts due to selective dissolution of active alloying elements. One way to prevent this is to make the molten salt reducing. For the KCl + MgCl 2 eutectic salt mixture, pure Mg can be added to achieve this. However, Mg can form intermetallic compounds with nickel at high temperatures, which may cause alloy embrittlement. This work shows that an optimum level of excess Mg could be added to the molten salt which will prevent corrosion of alloys like 316 H, while not forming any detectable Ni-Mg intermetallic phases on Ni-rich alloy surfaces.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Electrochemical recovery of Nd using liquid metals (Bi and Sn) in LiCl-KCl-NdCl 3

Highly efficient recovery of Nd into liquid metals of Bi and Sn was achieved in molten LiCl-KCl-NdCl 3 electrolyte at 773–973 K by leveraging the strong interactions of Nd with liquid metals. Based on the emf measurements of Nd-Sn and Nd-Bi alloys, the activity values of Nd were determined as low as 1.1–5.8×10 –13 in both liquid metals at 973 K while the solubility of Nd was found to be 1.46 mol% in Sn and 5.65 mol% in Bi. Both liquid metals demonstrated high round-trip coulombic efficiencies (>99.3%) during deposition-removal cycles of 10–50 mA cm –2 and high recovery capacity up to approximately 20 mol% Nd beyond the solubility limit. In addition, a high Nd recovery yield (84–90%) with respect to the applied charge was confirmed based on chemical analysis of electrolysis products in Bi after constant current electrolysis (–50 mA cm –2 ) at 873–973 K. Overpotentials during the Nd deposition process were attributed to charge-transfer and mass-transport resistances based on the current-potential curve and electrochemical impedance spectroscopy. The charge-transfer kinetics of Nd deposition into liquid metals was facile with high exchange current densities at ~220 mA cm –2 . Finally, the exceptionally high recovery efficiency for Nd in the molten chloride is thought to result from strong chemical interactions (i.e., low activity) of Nd in liquid metals that encourage one-step reduction, i.e., Nd 3+ + 3e → Nd(in Bi or Sn) by effectively suppressing side reaction pathways from multivalent states (Nd 2+ and Nd 3+ ).

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

Preparation of a uranium monocarbide anode and electrochemical characterization in molten LiCl-KCl-UCl 3

Porous uranium carbide (UC) pellets possessing moderate electrical conductivity were synthesized by reaction of UO 2 with graphite at temperatures up to 1550°C under rough vacuum. Conversions as high as 98% were achieved at soak times of 2-4 hours. The electrochemistry of the UC pellets in molten LiCl-KCl-6.5 wt% UCl 3 was explored using a variety of techniques including DC polarization methods, cyclic voltammetry, chronopotentiometry and bulk electrolysis. Here, the electrode reaction for anodic dissolution was found to be kinetically controlled by dissociation of UC to a transition state complex that was hypothesized to consist of a uranium atom partially complexed by chloride ions. Precise measurements of current efficiencies using chronopotentiometry indicated upper limits of 90.9 ± 3.4% and 98.3 +1.7/-3.7% for anode and cathode, respectively, when operating at anodic overpotentials near +300 mV. Bulk electrolysis of a UC pellet performed by passing 98% of the theoretical charge resulted in nearly complete recovery of its uranium content as highly pure metal at the cathode.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Thermodynamic properties of Gd-Bi alloys determined by emf measurements in LiCl-KCl-GdCl 3 electrolyte

Thermodynamic properties of binary Gd-Bi alloys (mole fraction, x Gd = 0.02–0.35) were determined using electromotive force (emf) measurements in molten LiCl-KCl-GdCl 3 electrolyte in complement with structural, microstructural, and thermal characterization. X-ray diffractometry (XRD) and scanning electron microscopy (SEM) identified the phase constituents of Gd-Bi alloys (x Gd = 0.02–0.35) as Bi matrix and GdBi compound. According to differential scanning calorimetry (DSC) measurements up to 1250 K, a eutectic transition [L = Bi + GdBi] was observed at 543 K but the reported peritectic transition [L + GdBi = GdBi 2 ] was not detected, suggesting the absence of the GdBi 2 compound. Based on structural, microstructural, and thermal characterization of Gd-Bi alloys (x Gd = 0.02–0.35), the GdBi 2 compound was not detected, and its thermodynamic stability is questionable. The emf of Gd-Bi alloy (x Gd = 0.16) at 700–1048 K relative to Gd(s) was measured by electrodepositing pure Gd metal at 25 K increments. Further, the emf values of Gd-Bi alloys were determined via coulometric titration of Gd into liquid Bi using a two-phase [L + GdBi] alloy as a reference electrode at 773–973 K. The solubility of Gd in liquid Bi was also estimated to be 0.50 mol% (773 K), 0.99 mol% (873 K), and 2.21 mol% (973 K) and the excess partial molar Gibbs energy (Δ$\mathrm{\bar{G}^{ex}_{Gd}}$) of liquid Gd-Bi alloys was as low as 65 kJ mol –1 , indicating strong chemical interactions between Gd and Bi.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Electrochemical properties of Gd(III) ions in LiCl-KCl-GdCl 3 at 723–1023 K

Electrochemical behavior of Gd(III) ions in molten LiCl-KCl-GdCl 3 was investigated at 723–1023 K via cyclic voltammetry using tungsten as a working electrode, Gd-Bi (mole fraction, x Gd = 0.16) as a reference electrode, and Gd-Bi (x Gd = 0.02) as a counter electrode. A single reduction–oxidation wave was observed, confirming a single-step, 3-electron transfer Gd(III)/Gd transition. The cathodic peak potential exhibited minimal change (<13 mV) over a wide range of scan rates (0.05–0.30 V s –1 ), indicating facile charge transfer kinetics (i.e., a reversible electrode process). A nucleation overpotential associated with solid Gd deposition was observable at low temperatures (T < 823 K). The mass transport properties of Gd(III) ions were estimated using the Berzins and Delahay relation based on diffusion-limiting peak current. The diffusivity values were determined to be D Gd(III) = 0.5–2.7 × 10 –5 cm 2 s –1 at 723–1023 K with an associated activation energy of E a = 33.9 (±1.0) kJ mol –1 . Finally, the two-phase [liquid + GdBi] Gd-Bi alloy reference electrode experienced less than 0.5 mV of drift over 5 days of repeated electrochemical measurements, indicating high stability.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Electrochemical recovery of Gd into liquid Bi in molten LiCl-KCl-GdCl 3

The electrochemical recovery of Gd into liquid Bi electrodes was investigated in molten LiCl-KCl-GdCl 3 electrolyte at 773–973 K using constant currents of 10–150 mA cm −2 . High round-trip coulombic efficiency (>97 %) was demonstrated for deposition and removal of Gd into and from liquid Bi at all temperatures, confirming chemically reversible electrode reactions towards high recovery yield of Gd using liquid Bi. Furthermore, the overpotential associated with deposition of Gd into the liquid Bi electrode gradually increased with current density and decreased with temperature. At the lowest temperature of 773 K, a steep increase in overpotential was evident at high current densities due to slower mass transport and low solubility of Gd in liquid Bi (0.5 at.% Gd). Based on the impedance spectra of Bi electrodes at 773–973 K, the exchange current density was estimated to be 110–220 mA cm −2 , indicating facile charge transfer at the liquid electrode-electrolyte interface. Post-mortem characterization of Bi cathodes after electrolysis at 873 K indicated the formation of a solid GdBi(s) compound layer at the Bi electrode surface. Chemical analysis of Bi cathodes at various deposited Gd compositions resulted in Faradaic efficiencies of ∼75–84 %, promising a high recovery yield of Gd from molten salts using a strongly-interacting liquid Bi electrode.

36 - MATERIALS SCIENCE↗
DOE OSTI2023

Temperature and anion ligand field dependence of LnCl 3 (Ln = Nd, Dy, Sm) electronic absorption spectra in LiCl–KCl eutectic molten salt

A comprehensive knowledge of the coordination, bonding, and speciation of elements in molten salt mixtures is necessary to understand and predict the chemical and physical properties of the salt. Absorption spectroscopy can yield information about the chemistry of species of interest in alkali halide molten salt mixtures by revealing information about the electronic structure and transitions of those species. In this study, ultraviolet (UV), visible (vis), and near-infrared (NIR) absorption spectroscopy was used to examine changes to the electronic structure of trivalent Nd, Sm, and Dy in LiCl–KCl eutectic molten salt with changes in temperature and the anion composition of the melt. With increasing temperature, changes to spectral features suggest a distortion of the coordination complexes. Changes to lineshape with the substitution of alternative halide anions were examined and analyzed, revealing differences in the coordination for I – versus F – with the lanthanides. Gaussian peak fitting was used to show that the changes in lineshape with the progressive addition of F – anions can be explained by the superposition of a set of absorption bands from complexes with all Cl – anion ligands and a set of blueshifted absorption bands from complexes containing both F – and Cl – anion ligands. Finally, this work yields a new method to analyze and interpret change to electronic absorption spectra for f-block elements dissolved in alkali halide molten salts as well as new observations of the interactions of larger and smaller halide anions with lanthanides in Cl – -based molten salts.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2020

Temperature Dependence of Short and Intermediate Range Order in Molten MgCl 2 and Its Mixture with KCl

This article addresses the non-Debye-Waller temperature behavior in the intermediate range order for molten MgCl 2 and its mixtures with KCl from a theory, Molecular Dynamics and experimental X-ray scattering perspective and puts these findings in the context of discussions and controversies extending at least four decades. We find that these liquids are defined by two structural motifs. The first motif is associated with chains of positive-negative charge alternation; the second motif, which results in a prepeak in the structure function S(q), is associated with the interaction of Mg 2+ and Cl - ions that do not belong to the same charge alternation chain or aggregate. Our complementary X-ray scattering and computational results provide a quantitative explanation for the increase in intensity of the prepeak with temperature as opposed to the behavior of other peaks following normal Debye-Waller behavior. We note temperature has opposite effects on the prevalence of each of the two structural motifs, and the enhancement of one pattern appears to be at the detriment of the other. Whereas the intensity in S(q) associated with the charge alternation motif is diminished at higher temperature the opposite is true for the prepeak associated with the intermediate range order due to the second structural motif.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Anatomy of Local Structural Disorder of Ni(II) Species in MgCl 2 –KCl Molten Salts

Understanding the speciation of metal ions dissolved in molten salts (MS) is critical for enabling a broad range of high-temperature energy applications, including MS nuclear reactors and concentrated solar power plants. However, due to the inherent dynamicity of metal species in the MS environment and the strong temperature dependencies of their multiple coexisting forms, they are difficult to resolve structurally. Herein, we show that combining in situ X-ray absorption spectroscopy (XAS) with ab initio molecular dynamics (AIMD) simulations is necessary to uncover and quantify the coexisting coordination states of Ni(II) in molten MgCl 2 –KCl mixtures and explain how the temperature and salt composition control their relative populations. Furthermore, from the interionic angle and distance distributions of nickel in different coordination states obtained from AIMD simulations, it is evident that for each coordination state, the width and skewness of their bonding distributions increase with increasing coordination number. In conclusion, the combination of XAS with first-principles modeling to resolve metastable metal species in MS is critical for understanding their behavior over a wide range of temperatures and chemical environments in nuclear and solar applications.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Effect of Fluoride Anions on Nd(III) Electrode Processes and Nd Metal Recovery in LiCl–KCl–NdCl 3

Here, this work investigated the impact of fluoride anions on Nd metal recovery in LiCl–KCl–NdCl 3 electrolytes by introducing LiF at a molar F/Nd ratio of 9 at 773 K. The voltammetric measurements confirmed that the fluoride ions facilitated single-step Nd(III)/Nd reduction by promoting the stability of the Nd(III) state compared to two-step reduction (Nd(III)/Nd(II) and Nd(II)/Nd) in all-chloride electrolytes. The stabilized Nd(III) state in the LiF-containing electrolyte effectively suppressed partial Nd(III)/Nd(II) reduction and the back-dissolution of Nd metal via comproportionation. By suppressing these reactions, high round-trip Coulombic efficiencies of 77–86% were achieved in the LiF-containing electrolyte during selective Nd deposition–removal cycles compared to 53–59% in all-chloride electrolytes. The Faradaic yield for Nd metal recovery was estimated at 38.6% in the LiF-containing electrolyte following long-term electrolysis, more than three times higher than 11.3% in all-chloride electrolytes. These results confirm the beneficial effect of fluoride ions on Nd metal recovery in low-melting chloride-based electrolytes, promising efficient Nd recovery at low temperatures.

11 - NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2022

Radiation-induced reaction kinetics of Zn 2+ with e S - and Cl 2 ˙ - in Molten LiCl–KCl eutectic at 400–600 °C

We report molten chloride salts are currently under consideration as combined coolant and liquid fuel for next-generation molten salt nuclear reactors. Unlike complementary light-water reactor technologies, the radiation science underpinning molten salts is in its infancy, and thus requires a fundamental mechanistic investigation to elucidate the radiation-driven chemistry within molten salt reactors. Here we present an electron pulse radiolysis kinetics study into the behaviour of the primary radiolytic species generated in molten chloride systems, i.e., the solvated electron (e S - ) and di-chlorine radical anion (Cl 2 ˙- ). We examine the reaction of e S - with Zn 2+ from 400–600 °C (E a = 30.31 ± 0.09 kJ mol -1 ), and the kinetics and decay mechanisms of Cl 2 ˙- in molten lithium chloride-potassium chloride (LiCl–KCl) eutectic. In the absence of Zn 2+ , the lifetime of e S - was found to be dictated by residual impurities in ostensibly “pure” salts, and thus the observed decay is dependent on sample history rather than being an intrinsic property of the salt. The decay of Cl 2 ˙- is complex, owing to the competition of Cl 2 ˙- disproportionation with several other chemical pathways, one of which involves reduction by radiolytically-produced Zn + species. Overall, the reported findings demonstrate the richness and complexity of chemistry involving the interactions of ionizing radiation with molten salts.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2023

Impact of iodide ions on the speciation of radiolytic transients in molten LiCl–KCl eutectic salt mixtures

The fate of fission-product iodine is critical for the deployment of next generation molten salt reactor technologies, owing to its volatility and biological impacts if it were to be released into the environment. To date, little is known on how ionizing radiation fields influence the redox chemistry, speciation, and transport of iodine in high temperature molten salts. Here we employ picosecond electron pulse irradiation techniques to elucidate for the first time the impact of iodide ions (I – ) on the speciation and chemical kinetics of the primary radiation-induced transient radicals generated in molten chloride salt mixtures (e S – and Cl 2 ˙– ) as a function of temperature (400–700 °C). In the presence of I – ions (≥ 1 wt% KI in LiCl–KCl eutectic), we find that the transient spectrum following the electron pulse is composed of at least three overlapping species: the e S – and the Cl 2 ˙– and ICl ˙– radical anions, for which a deconvoluted spectrum of the latter is reported here for the first time in molten salts. This new transient spectrum was consistent with gas phase density functional theory calculations. The lifetime of the e S – was unaffected by the addition of I – ions. The newly observed interhalogen radical anion, ICl˙ – , exhibited a lifetime on the order of microseconds over the investigated temperature range. The associated chemical kinetics indicate that the predominate mechanism of ICl˙ – decay is via reaction with the Cl 2 ˙– radical anion. The iodine containing product of this reaction is expected to be ICl 2 – , which will have implications for the transport of fission-product iodine in MSR technologies.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2024

Kinetics of Radiation-induced Cr( II ) and Cr( III ) Redox Chemistry in Molten LiCl-KCl Eutectic

Chromium (Cr) is a frequent constituent of the metal alloys proposed for molten salt nuclear reactor (MSR) applications, and is typically the least noble metal ion present. Consequently, chromium is preferentially corroded into molten salt solutions. Here, the redox poise and redox cycling of chromium ions in the salt can greatly influence its corrosivity towards structural alloys, ultimately impacting the longevity of MSR systems. Radiation-induced chemistry is expected to play a significant role in determining the chromium oxidation state distribution during MSR operations. In the present research, electron pulse radiolysis techniques were employed to characterize the reactivity of Cr(II) and Cr(III) ions with primary radiolysis products in molten lithium chloride–potassium chloride (LiCl–KCl) eutectic over a temperature range of 400–600 °C. Both chromium oxidation states were found to rapidly react with the primary products of molten chloride salt radiolysis, i.e., the solvated electron (e S - ) and the dichlorine radical anion (Cl 2 ˙ - ). For reactions with the e S - , second-order rate coefficients (k) of k = (4.1 ± 0.2) and (6.1 ± 0.3) × 10 10 M -1 s -1 at 400 °C for Cr(II) and Cr(III), respectively, were determined. Temperature-dependent measurements allowed for the derivation of activation parameters for electron capture by Cr(II) and Cr(III). Both chromium ions also react with Cl 2 ˙ - , k = (7.2 ± 0.3) and (1.4 ± 0.1) × 10 9 M -1 s -1 at 400 °C for Cr(II) and Cr(III), respectively.

37 - INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL C↗
DOE OSTI2021

Parametric Study of Used Nuclear Oxide Fuel Constituent Dissolution in Molten LiCl-KCl-UCl 3

Prior work identified dissolution of used nuclear oxide fuel constituents from a uranium oxide matrix into molten LiCl-KCl-UCl 3 at 500°C, prompting a subsequent series of three progressive studies (including an initial scoping study, an electrolytic dissolution study, and a chemical-seeded dissolution study) to further investigate associated parameters and mechanisms. Thermodynamic calculations were performed to identify possible reaction mechanisms and their propensities in used oxide fuel constituent dissolution. Used nuclear oxide fuels with varying preconditions from fast and thermal test reactors were separately immersed in the subject salt system to assess fuel constituent migration from the bulk fuel matrix to the salt phase in an initial scoping study. Dissolution of expected fuel constituents, including alkali, alkaline earth, lanthanide, and transuranium oxides, into the chloride salt phase varied widely, ranging from 12% to 99% in the initial study. Uranium isotope blending between the salt phase and bulk fuel matrix was also observed, which was attributed to reducing conditions in the fuel matrix. Electrolytic and chemical-seeded dissolution studies were subsequently performed to effect reducing conditions in the fuel. Other parameters, including temperature (at 500°C, 650°C, 725°C, and 800°C) and uranium trichloride concentrations (at 6, 9, and 19 wt% uranium), were investigated in the latter two studies, resulting in fuel constituent dissolution above 90%. Extents of dissolution were based on initial and final fuel constituent concentrations in the oxide fuels following operations in the salt and subsequent removal of the salt via distillation. Finally, in this series of progressive studies, oxide fuel preconditioning and in situ reducing conditions, along with elevated temperature and uranium trichloride concentrations, were the primary parameters promoting used nuclear oxide fuel constituent dissolution in accordance with identified reaction mechanisms.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2022

Composition-transferable machine learning potential for LiCl-KCl molten salts validated by high-energy x-ray diffraction

Unraveling the liquid structure of multicomponent molten salts is challenging due to the difficulty in conducting and interpreting high-temperature diffraction experiments. Here, motivated by this challenge, we developed composition-transferable Gaussian approximation potential (GAP) for molten LiCl-KCl. A DFT-SCAN accurate GAP is active-learned from only ~1100 training configurations drawn from 10 unique mixture compositions enriched with metadynamics. The GAP-computed structures show strong agreement across high-energy x-ray diffraction experiments, including for a eutectic not explicitly included in model training, thereby opening the possibility of composition discovery.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2020

Recovery of Alkaline-Earths into Liquid Bi in Ternary LiCl-KCl-SrCl 2 /BaCl 2 Electrolytes at 500 °C

Electrochemical reduction of Sr 2+ and Ba 2+ into liquid Bi was investigated in dilute concentrations of SrCl 2 /BaCl 2 (0-5 mol%) in LiCl-KCl electrolytes at 500 °C to ascertain the limit of liquid Bi electrodes for alkaline-earth recovery. Analysis of the electrodes after constant current electrolysis to the specific charge of 270 C g -1 showed Sr 2+ ions consuming 29% of charge at 5 mol% before dropping to 8%-10% of the total charge at 0.45-0.72 mol% SrCl 2 . Ba 2+ ions consumed 54% at 5 mol% BaCl 2 before decreasing to 22%-24% at 0.42-0.89 mol% BaCl 2 ; substantial co-deposition of Li was observed in all chemistries, consuming up to 53% of charge. Considering only 1% of the total charge was consumed for depositing Ba 2+ and Sr 2+ ions in ~0.1 mol% SrCl 2 /BaCl 2 electrolyte, the lower recovery limit of Bi for alkaline-earth elements is suggested to be at ~0.4 mol% SrCl 2 /BaCl 2 to achieve appreciable deposition of alkaline-earths (>1.5 mol% Ba/Sr in liquid Bi). The overpotentials of liquid Bi at 5 mol% of SrCl 2 /BaCl 2 were evaluated by electrochemical impedance spectroscopy. The co-deposition of Sr and Li exhibited the largest increase in charge transfer resistances implying sluggish charge transfer kinetics whereas the co-deposition of Ba and Li exhibited a large increase in mass transport resistances due to the slow diffusion of Ba 2+ ions in the electrolyte.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗