Molten Sodium Research Articles

A Fundamental Study on the Preparation of Sodium Tungstate from Wolframite via the Smelting Process

Tungsten is a high-value resource with a wide range of applications. The tungsten metal is produced via ammonium paratungstate, which is a multi-stage process including leaching, conversion, precipitation, calcination, and reduction. A short process to produce tungsten metal from the electrolysis of molten sodium tungstate has been demonstrated. However, sodium tungstate cannot be directly produced from wolframite in the conventional hydrometallurgical process. There was no information reported in the literature on producing sodium tungstate directly from tungsten concentrates. The present study proposed a simple and low-cost process to produce sodium tungstate by high-temperature processing of wolframite. The mixtures of wolframite, sodium carbonate, and silica were melted in air between 1100 and 1300 °C. High-density sodium tungstate was easily separated from the immiscible slag, which contained all impurities from wolframite, flux, excess sodium oxide, and dissolved tungsten oxide. The slag was further water leached to recover sodium tungstate in the solution. Effects of Na2CO3/Ore and SiO2/Ore ratios, temperature, and reaction time on the recovery of tungstate and the purity of sodium tungstate were systematically studied. Sodium tungstate containing over 78% WO3 was produced in the smelting process, which is suitable for the electrolysis process. The experimental results will provide a theoretical basis for the direct production of sodium tungstate from wolframite. The compositions of the WO3-containing slags and sodium tungstate reported in the present study fill the knowledge gap of the tungsten-containing thermodynamic database. Further studies to use complex and low-grade tungsten concentrates to produce sodium tungstate are underway.

Activation of Methane in Vapor and Molten Sodium Catalyst

Activation of Methane in Vapor and Molten Sodium Catalyst

Рекуперация и очистка газовых выбросов целлюлозного производства

For pulp production, large-scale enterprises have been built which, while in operation, are subject to new requirements, different from the design ones, for economic efficiency, labour safety, as well as impact on the local population and the environment. Significant success in this work has been achieved by changing the liquor recovery technology, switching to burning black liquor of increased concentration, which makes it possible to almost completely eliminate the largest source of hydrogen sulfide and methyl mercaptan emissions with flue gases, reduce sulfur losses and improve energy efficiency of soda recovery boilers. Another significant source of soda recovery boiler emissions is a smelt dissolving tank vent. An important technological operation of dissolving molten sodium salts with weak white liquor supplied from the causticization shop takes place in the tank. The modern development of smelt leaching technology is related to the improvement of equipment compatible with the technology of regeneration of chemical reagents for pulp production. Heat exchangers and gas purifiers of “gas-liquid” systems, easier to adapt to technological requirements compared to other systems, are installed on the dissolving tank vent. The installation of such equipment provides the change in the smelt leaching technology, and affects the technology of causticization and lime recovery. This article covers the research of the relationship between the technical solutions ensuring the safety of personnel in the boiler shop, heat and chemicals recovery, as well as purification of gas emissions and the changes in the technology of smelt leaching in the soda recovery boiler of the pulp mill. On the basis of experimental data and a mathematical model of the movement of the vapour-gas mixture in the smelt dissolving tank vent, the technological feasibility of installing heat exchangers at different heights of the vent and the possibility of effective purification of gas emissions using a direct-flow sprayer have been considered. The applicability of the irrigation of the steam-gas flow with weak white liquor, which is formed during the cycle of chemical regeneration in pulp production, as well as the conditions for ensuring reliable operation of gas purification equipment, have been investigated. The quantitative characteristics of the necessary change in consumption and composition of weak white liquor and the methods of its supply to the dissolving tank have been obtained.

Glass-based sealants for joining α to β’’-Al2O3 in Na–Zn batteries

This study deals with the design and the characterisation of glass-based materials for the hermetic sealing of ceramic components (α-to β’’-Al2O3) in solid-electrolyte cells operating at approximately 300 °C. A silica-based commercially available glass and a newly developed silica-free glass, potentially resistant to corrosion by molten sodium salts, are reviewed and discussed. 25 wt% alumina powder is incorporated into both formulations. The sintering behaviour of the glass systems and their wetting characteristics on alumina are evaluated at the selected sealing temperatures: 900 °C for 40 min (for the silica-based system) and 700 °C for 1 h (for the silica-free system). The viscosity of both glass systems at these temperatures, which is approximately 105 Poise, is deemed suitable for facilitating proper glass flow and bonding with the alumina components. Furthermore, the coefficient of thermal expansion (CTE) of the potential sealant candidates is investigated. The results demonstrate good compatibility between the glass-based systems (CTE ≈ 7–7.6· 10−6 K−1 at temperatures ranging from 100 to 300 °C) and α- and β’’-Al2O3 (CTE ≈ 7.3· 10−6 K−1 within the same temperature range). The microstructural analysis conducted using field-emission scanning electron microscopy (FE-SEM) confirms good thermo-mechanical matching between the glass-based sealants and the alumina ceramic components and that no reaction occurs during the sealing between alumina powder and the glass matrix.

Ferrimagnetic devitrified glass doped with copper by ion exchange: Microstructure, bioactivity and antibacterial properties

In this work, the ion-exchange technique in molten salts was investigated to introduce copper ions in a bioactive and ferrimagnetic devitrified glass. This approach aimed to develop a magnetic and bioactive material for oncologic bone implants, able to join the ability to promote bone bonding to hyperthermic therapy while simultaneously lowering the risk of developing post-surgery infections. The ion-exchange approach was developed in order to overcome experimental critical issues related to the influence of copper introduction as a starting reagent, during the material synthesis, on magnetite nucleation.The magnetic devitrified glass was prepared by melt and quenching route, followed by ion exchange in a mixture of molten sodium and copper nitrates, in three different Na/Cu molar ratios (20, 200, 2000). The obtained samples were analysed in terms of morphology, composition, ability to release heat, bioactivity and antibacterial properties. The results revealed that copper ion-exchange involved both sodium and calcium ions and the precipitation of few amounts of copper oxide aggregates occurred. The crystalline nature of the starting material and its ability to reach the temperature needed for hyperthermia, under exposition to an alternating magnetic field, were not affected. A bacteriostatic effect was obtained by samples with the highest copper amount and the copper doping did not affect the bioactivity of the glass ceramic.

Batteries Worth Their Salt: Targeting Next Generation Stationary Storage with Molten Salt Electrolytes

There is an imminent need for batteries capable of meeting the evolving demands of a growing stationary storage landscape, one rich in renewable energy sources and challenged with unprecedented global electrification. Key to our future electrical grid, desirable large-scale, long-duration batteries must not only meet demands for high power and energy density, but they must be safe, cost-effective, and should be sustainably sourced from earth-abundant materials. Here, we will highlight our research and development of low temperature molten salt batteries that employ active materials such as sodium, aluminum, iron, chloride, and iodide. We will demonstrate the promise of our approach through a low-temperature (100°C) molten sodium battery that comprises a molten sodium anode, a solid-state NaSICON ceramic separator, and a low-cost molten metal-halide salt catholyte. These batteries, with remarkable voltages greater than 3.1V, are capable of months of cycling as well as high current charge and discharge behavior, greater than 50mA/cm2. Here, we will not only highlight these performance metrics, but we will describe how we used specialized electrochemical and chemical characterization technique to understand the impacts of molten salt electrolyte composition, electrochemistry, and interfacial interactions on battery performance. By understanding the connections between specific electrochemical phenomena and battery chemistry, we have learned to improve battery performance through tuning of properties, such as molten salt Lewis acidity and current collector composition. This scientifically-motivated battery design approach continues to enable agile innovation and advances to realize the potential of molten salt batteries as a new, impactful stationary storage technology.Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.

Sodium chloride modulated construction of hollow Co/Co3O4 heterostructure with enhanced mesoscale diffusion towards overall water splitting

Fabricating an efficient electrocatalyst for both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) isthe most challenging task for overall water splitting. Herein, we utilized the confinement effect of molten sodium chloride (NaCl) to controllably prepare hollow Co/Co3O4 nanoparticles embedded into nitrogen-doped carbon (H-Co/Co3O4-NC). Experimental and theoretical investigations revealed that the interfacial interaction within Co/Co3O4 heterostructure played a pivotal role in modulating the electronic structure and facilitating the electron transfer. Meanwhile, the superiority of hollow nanostructure could promote the mesoscale mass diffusion. Remarkably, the as-prepared H-Co/Co3O4-NC catalyst achieved the low overpotentials of 316 mV and 252 mV towards OER and HER, respectively, which delivered overall water splitting with the potential of 1.76 V at a current density of 10 mA cm−2.

Molecular dynamics simulation of homogeneous nucleation of melting in superheated sodium crystal

The melting process and nucleation behaviour of sodium (Na) crystals are crucial for the frozen start-up of high-temperature sodium heat pipes and the working performance of molten sodium batteries. Equilibrium melting and the homogeneous nucleation of melting in superheated Na crystal are studied by molecular dynamics simulation. The thermodynamic properties and nucleation of Na crystal during the heating process are investigated by the characterization of the density, radial distribution function (RDF), self-diffusion coefficient (D), nucleation rate (Ihom), etc. Firstly, the equilibrium melting of Na crystal is simulated and verified by the single-phase method. Results show that Na's equilibrium melting temperature, densities, and RDF simulated match well with experimental values, demonstrating that the EAM/FS potential is suitable for studying the melting processes of Na crystal. Secondly, the calculated D of liquid Na increases approximately linearly with rising temperature within 440 K∼540 K and fits with experimental data well. The activation energy for the diffusion of Na obtained by linear fitting is 1.6406·10-20 J, which agrees well with the observed values. Finally, the homogeneous nucleation of melting in superheated Na crystal is analyzed. It is found that the Ihom of melting in superheated Na crystal rises exponentially with increasing temperature, which is consistent with the prediction in literature. The kinetic stability limit of superheated Na crystal is 468.3 K, and the relation between the Ihom of melting in superheated Na crystal and temperature is given. The physical properties and nucleation theory of Na crystal simulated during the melting can provide theoretical support for sodium's heat and mass transfer-related applications, such as sodium heat pipes and sodium batteries.

Oxidative Dissolution of Cemented Tungsten Carbides in Molten Sodium Carbonate by Addition of Copper(I) Oxide as Oxidizing Agent for Tungsten Recycling

Due to the monopolized supply of tungsten resource, it is important to efficiently recycle tungsten scrap for use as a secondary resource. The recycling of tungsten from cemented carbide tools by the molten carbonate method was investigated using simulated hard and soft scrap (carbide tool tips and WC powder, respectively). The oxidative dissolution of tungsten was examined in molten Na2CO3 under Ar–O2–CO2 atmospheres at 1173 K. Based on the immersion potentials of Cu, W, Co, C, and WC–Co, Cu2O was suggested to work as an oxidizing agent for tungsten dissolution. The oxidative dissolution rate for carbide tool tips with 12.8 mol% Cu2O addition reached 57 mg h−1 for the reaction time of 2.5 h, equivalent to 0.32 mm h−1. The decrease in the dissolution rate after 2.5 h was attributed to the decrease in the Cu(I) ion concentration in the melt and the inhibition of ion diffusion by the deposited metallic Cu. No violent reaction leading to explosion was observed, even for the oxidative dissolution of fine WC powder with a large surface area. Thus, this method provides significant safety improvements compared to the molten nitrate method.Graphical

(Best Student Presentation) Extending the NaCl-AlCl3 Phase Diagram to Enable Low-Cost, Long-Duration Na-Al Batteries for the Grid

Achieving deep grid decarbonization via intermittent renewable power sources requires extensive grid-scale energy storage technologies to deliver stable power during periods of low generation. Doing so at scale and at low cost further adds to this challenge, as current solutions generally rely on geographically limited solutions such as pumped hydro storage, or costly battery chemistries focusing primarily on Li-ion technologies. As an alternative, battery systems based on lower cost materials such as sodium offer an attractive alternative for low-cost, scalable, and non-geographically limited electrochemical energy storage.This work combines an abundant and inexpensive molten sodium metal anode with a cost-effective aluminum cathode to provide a proof-of-concept alternative for grid-scale energy storage. Building on prior work utilizing the high reversibility of the neutral sodium chloroaluminate (NaAlCl4) molten salt electrolyte commonly used for classic molten sodium batteries, this work demonstrates greater capacity utilization of the NaCl-AlCl3 binary system by ‘overcharging’ this Na-Al battery to form an acidic chloroaluminate catholyte, NaAl2Cl7. Leveraging the reaction between NaAlCl4 and NaAl2Cl7 in conjunction with that between Al/NaCl and NaAlCl4 advantageously utilizes the majority of Na available in the cathode for capacity, in addition to providing a higher discharge voltage (~ 2 V compared to ~ 1.6 V for the NaAlCl4 reaction), thereby adding ~ 119 Wh kg-1 additional specific energy, on top of the 493 Wh kg-1 theoretical specific energy of the neutral Na-Al battery reaction between Al/NaCl and NaAlCl4.Fundamental aspects of the acidic chloroaluminate reaction are investigated, showing that cells using only the acidic reaction are able to cycle for hundreds of cycles. The acidic reaction between NaAlCl4 and NaAl2Cl7 occurs via a solution-phase reaction, unlike the two-phase neutral reaction between NaCl/Al and NaAlCl4, and we confirm via Raman and NMR spectroscopies that complete conversion to NaAl2Cl7 occurs at end of charge. Na-Al batteries utilizing both reactions demonstrate high areal capacity (~ 46 mAh cm-2) and excellent reversibility. Enabled by the rapid mass transfer and solid-liquid reaction mechanism of the chloroaluminate catholyte, a higher areal capacity cell with ~ 132 mAh cm-2 is demonstrated, allowing a discharge duration of 28.2 h, implying that this Na-Al battery chemistry may be suitable for long-duration energy storage for grid applications. Finally, the raw active materials cost of this battery is estimated to be only ~ $7 kWh-1, which is promising for enabling low-cost renewable power utilization for the grid. Figure 1

Sodium Penetration in Nasicon Solid Electrolytes Under High Current

High conductivity solid electrolytes, such as NaSICON, are poised to play an increasingly important role in safe, reliable battery-based energy storage, enabling a new class of sodium-based batteries. Coupled demands of high current densities (≥0.1 A cm-2) and low temperature (<200 °C) operation, combined with increased discharge times for long duration storage (>12 h), challenge the limitations of solid electrolytes. Here, we explore the penetration of sodium into NaSICON at 0.1 A cm-2 in a symmetric molten sodium cell. Previous studies of β’’-alumina proposed that Poiseuille pressure-driven cracking (Mode I) and low levels of electronic conductivity leading to ion-electron recombination (Mode II) can cause metal accumulation within solid electrolytes, but a comprehensive study at high current density is necessary. To understand and differentiate these modes in NaSICON, this work employs unidirectional galvanostatic testing of Na|NaSICON|Na symmetric cells at 0.1 A cm-2 over 23 1-hour intervals at 110 °C. While galvanostatic testing shows a relatively constant, yet increasingly noisy voltage profile, electrochemical impedance spectroscopy (EIS) between intervals reveals a significant decrease in cell impedance which can be correlated with sodium metal penetration, as observed in scanning electron microscopy (SEM). Significant sodium accumulation from the stripping-side electrode suggests that Mode II failure may be far more prevalent than previously considered. Further, these findings suggest that total charge transported per unit area (mAh cm-2), an important parameter for long duration storage, may be a more critical parameter than current density (mA cm-2) when examining solid electrolyte failure. Together, these results provide a better understanding of the limitations of NaSICON solid electrolytes under high current density and can guide the design of coatings to improve electrode-electrolyte interfaces.

Molten Sodium Batteries – Lewis Acidity of AlCl3/NaI Catholyte Impedes NaSICON Interface

Low temperature molten sodium batteries with sodium metal anodes, NaSICON solid-state separators, and sodium halide salt catholytes are low cost, earth-abundant technologies for grid-scale energy storage.1-3 We compared batteries with NaI/AlCl3-based molten salt catholytes of differing Lewis acidities at 110 °C. Batteries with >50 mol% AlCl3 (acidic catholytes) experienced a linear decline in energy efficiency during cycling, whereas batteries with >50 mol% NaI (basic catholytes) maintained 95% energy efficiency for 100 cycles (5 months) at 2.5 mA cm-2. A 3-electrode cell was developed, enabling electrochemical identification of the NaSICON-catholyte interface as the source of increased impedance. Complementary physical and chemical characterization of the NaSICON exposed to acidic and basic catholytes showed no changes in crystallinity, bulk morphology, or bulk chemical composition, but surface sensitive X-ray photoelectron spectroscopy (XPS) revealed subtle changes in the local NaSICON surface chemistry. In addition, Raman spectroscopy indicated that basic catholytes lack the dimer species Al2Cl6I- present in acidic catholytes. These results suggest that one means to enable efficient and stable battery cycling is maintaining Lewis-basic NaI/AlCl3, which avoids deleterious interactions at the NaSICON-catholyte interface. Recent progress towards achieving high cycling rates in these molten salt systems will also be shared.References L. J. Small, A. Eccleston, J. Lamb, A. C. Read, M. Robins, T. Meaders, D. Ingersoll, P. G. Clem, S. Bhavaraju and E. D. Spoerke, J. Power Sources, 360, 569 (2017).S. J. Percival, L. J. Small and E. D. Spoerke, J. Electrochem. Soc., 165, A3531 (2018).M. M. Gross, S. J. Percival, L. J. Small, J. Lamb, A. S. Peretti and E. D. Spoerke, ACS Appl. Energy Mater., 3, 11456 (2020). Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.

Molten Sodium Penetration Through Solid-State Nasicon Electrolytes Under High Current

High conductivity solid electrolytes, such as NaSICON, are poised to play an increasingly important role in safe, reliable battery-based energy storage, enabling a new class of sodium-based batteries. Increasing demands of both high current densities (≥0.1 A cm-2) and low temperature (<200 °C) operation, coupled with increased discharge times for long duration storage (>12 h), challenge the limitations of solid electrolytes. Here, we explore the penetration of sodium into NaSICON at 0.1 A cm-2 in a symmetric molten sodium cell. Previous studies of β’’-alumina proposed that Poiseuille pressure-driven cracking (Mode I) and low levels of electronic conductivity leading to ion-electron recombination (Mode II) can cause metal accumulation within solid electrolytes, but a comprehensive study at high current density is necessary. To understand and differentiate these modes in NaSICON, this work employs unidirectional galvanostatic testing of Na|NaSICON|Na symmetric cells at 0.1 A cm-2 over 23 1-hour intervals at 110 °C. While galvanostatic testing shows a relatively constant, yet increasingly noisy voltage profile, electrochemical impedance spectroscopy (EIS) between intervals reveals a significant decrease in cell impedance which can be correlated with sodium metal penetration, as observed in scanning electron microscopy (SEM). Significant sodium accumulation from the stripping-side electrode suggests that Mode II failure may be far more prevalent than previously considered. Further, these findings suggest that total charge transported per unit area (mAh cm-2), an important parameter for long duration storage, may be a more critical parameter than current density (mA cm-2) when examining solid electrolyte failure. Together, these results provide a better understanding of the limitations of NaSICON solid electrolytes under high current density and can guide the design of coatings to improve electrode-electrolyte interfaces.

Evaluation of heterogeneous metal-sulfide molten salt slurry systems for hydrogen production through methane pyrolysis

In this paper we evaluate the addition of suspended metal sulfides to molten salt slurry systems for methane pyrolysis. Stability tests are completed at 800 °C in eutectic molten sodium and potassium bromide for 6 h. In addition, the slurries are evaluated from 800 to 900 °C. It is demonstrated that the addition of metal sulfides does enhance hydrogen production over a 6-h stability test. MoS2 2-μm particles suspended in NaBr-KBr demonstrated 2.75% methane conversion at 800 °C with a 120 mm bubble path, with an apparent activation energy of 57 kJ mol−1. In addition, the MoS2 particles demonstrated good structural stability but deactivated primarily through coking in the melt. The experiments demonstrate the potential to reduce the operating temperature of molten salt methane pyrolysis, although there is notable instability. MoS2 in one run was observed to steadily decline from a peak of 2.84% methane conversion to 1.71% in 6 h. This instability is the result of coking; leaching is also observed in WS2 samples.

Extraction of Lithium from β-Spodumene via Ion Exchange in Molten Sodium Salts

Extraction of Lithium from β-Spodumene via Ion Exchange in Molten Sodium Salts

Synthesis of Planet‐Like Liquid Metal Nanodroplets with Promising Properties for Catalysis

AbstractLiquid metal nanodroplets are an emerging class of underexplored materials with significant potential in many applications, including catalysis, bio‐therapeutics, and phase‐change materials. These nanostructures are generally synthesized by mechanical agitation via ultrasonication of low‐melting metals like Ga. Once these materials are successfully synthesized, they can be suspended in a vast array of different solvents. However, one major issue arises specifically with liquid metal alloys which are found to de‐alloy in the sonication process. Here, it is demonstrated that this challenge can be overcome by undertaking sonication at high temperatures, suspending nanodroplets within molten sodium acetate (NaOAc). After cooling, the nanostructures become planet‐like nanodroplets which are covered by an interfacial oxide crust, feature a liquid metal mantle, and a solid core. The molten salt solvent can effectively be removed rendering this approach to be ideal, especially for catalysts. The proof‐of‐concept application is demonstrated by carrying out electrocatalytic ethanol oxidation, using the Cu–Ga system. The superior performance of the Cu–Ga nanodroplets highlights potential in catalyzing a vast array of reactions. Aside from the Cu–Ga system, this facile process can be applied to multiple other systems, including Ag–Ga, Zn–Ga, Bi–Ga, In–Cu, and Sn–Cu.

Detection of Off-Gassed Products From Molten Salts Using Laser-Induced Breakdown Spectroscopy.

The detection of off-gassed sodium from molten sodium nitrate (NaNO3) at temperatures between 330 °C and 505 °C and off-gassed calcium from molten lithium chloride-potassium chloride eutectic (LKE) mixtures at 510 °C with laser-induced breakdown spectroscopy (LIBS) was demonstrated. NaNO3 and LKE samples were melted in a custom-built crucible that promoted the generation of off-gassed products from the molten sample. The off-gassed products were analyzed with a LIBS system designed to probe the high-temperature environment. Na D emission lines, Na(I)588.99 nm and Na(I) 589.59 nm, were detected from the NaNO3 samples after reaching a temperature threshold, which indicated the occurrence of phase change. In LKE mixtures, the detection of Ca impurities at a concentration of 78 mg/kg was possible using the emission lines Ca(II) 393.66 nm and Ca(II) 395.85 nm. This work demonstrates the real-time monitoring capabilities of LIBS in high-temperature environments that simulate the conditions of molten salt reactors.

Characteristics and purification of Himalayan salt by high temperature melting

Abstract Himalayan rock salt contains a variety of minerals and trace elements, which is conducive to human health. The solutions of black rock salt and rose salt are alkaline, and the content of water insoluble matter is 0.34 and 0.083%, respectively. The element composition of water insoluble matter in rock salt is determined and analyzed. It is found that the main component of two kinds of rock salt water insoluble matter is soil. Due to the presence of water insoluble matter in rock salt, according to the different specific gravity of molten sodium chloride and insoluble matter, rock salt was purified by high-temperature melting method. Rose salt is mainly studied during purification. The results showed that the content of insoluble matter in rose salt decreased from 0.083 to 0.0024% after holding at 950°C for 40 min; the contents of arsenic, barium, and lead decreased to 0.0032, 0.61, and 0.21 mg·kg−1, respectively; the content of sodium increased to 39.24%, the contents of calcium, magnesium, and iron reached to 2,200, 855, and 1.31 mg·kg−1, respectively.

Electrode Blocking Due to Redox Reactions in Aluminum Chloride-Sodium Iodide Molten Salts

Iodide redox reactions in molten NaI/AlCl3 are shown to generate surface-blocking films, which may limit the useful cycling rates and energy densities of molten sodium batteries below 150 °C. An experimental investigation of electrode interfacial stability at 110 °C reveals the source of the reaction rate limitations. Electrochemical experiments in a 3-electrode configuration confirm an increase of resistance on the electrode surface after oxidation or reduction current is passed. Using chronopotentiometry, chronoamperometry, cyclic voltammetry, and electrochemical impedance spectroscopy, the film formation is shown to depend on the electrode material (W, Mo, Ta, or glassy carbon), as well as the Lewis acidity and molar ratio of I−/I3 − in the molten salt electrolytes. These factors impact the amount of charge that can be passed at a given current density prior to developing excessive overpotential due to film formation that blocks the electrode surface. The results presented here guide the design and use of iodide-based molten salt electrolytes and electrode materials for grid scale battery applications.

Miniature DC electromagnetic pumps of molten lead and sodium to support development of Gen-IV nuclear reactors

This work developed designs of submerged, dual-regions, miniature DC-EM pumps for circulating molten lead and liquid sodium at ≤500 °C without active cooling for use in ex-pile and in-pile test loops to support of materials and fuel developments for Gen-IV sodium and molten lead fast nuclear reactor. These pumps with two pumping regions are 57 mm, 66.8 mm, 95.4 mm, and 133.5 mm in diameter and have two Alnico 5 permanent magnets with Hiperco-50 pole pieces for focusing the magnetic field lines in the flow duct. The Equivalent Circuit Model (ECM) linked to the Finite Element Method Magnetics (FEMM) software in MATLAB platform calculated the pumps characteristics for a wide range of parameters. Also determined are the pumps dimensions for the highest cumulative pumping power and peak efficiency. These dimensions are the height, width, and length of the flow duct, the thickness of the Alnico magnets, the length of current electrodes, and the separation distance between the two pumping regions. For molten lead, the pumping power increases from 368 W to 728 W, and the peak efficiency from 14.7% to 31.6% with increased pump diameter from 57 mm to 133.5 mm. For liquid sodium, both the pumping power and peak efficiency are higher, increasing from 392 W to 767 W and from 44.3 to 51.2%, respectively, with increased pump diameter from 57 mm to 133.5 mm.