Molten Salt Research Articles

Eliminating nonuniform geometric effects for long-term stable electrochemical extraction of high-purity titanium.

Electrorefining of low-grade titanium is one of the strategies for achieving high-purity titanium. However, the presence of nonuniform geometric effects would be induced to impact the nonuniform geometric distribution of overpotential, leading to impurity dissolution and nonuniform Ti deposition. Here, in situ high-temperature characterizations on the molten salt electrorefining process are applied to establish an anodic dissolution principle for quantitatively evaluating nonuniform geometric effects of electrode. For eliminating the nonuniform geometric effects, coaxial anode-cathode configurations are designed to promote the nonuniform anodic dissolution and nonuniform cathodic deposition. Consequently, the geometric uniformity of titanium products on the cathodes is substantially enhanced, and thus, long-term stable electrorefining process (~12hours, ~330% increment compared to the electrode of reference configuration) and highly purified titanium products (99.2%) are achieved.

Confirmation of radicals auto-generated in [Bmim][PF6]/[C16mim][PF6]/water reverse micelles and the radical quantification based on the 1,1-diphenyl-2-picrylhydrazine (DPPHH) spectroscopic probe.

Ionic liquids (ILs) which belong to the molten salt of a high ionic environment exhibit a number of unique properties, including the formation of various heterogeneities in their microemulsion. We found that auto-generated radicals within a [Bmim][PF6]/[C16mim][PF6]/PBS reverse micelles (IL-RMs) and then the radicals were quantified in this study. For the radical confirmation, EPR spectroscopy with 5,5-dimethyl-1-pyrroline N-oxide (DMPO) free radical scavenger was carried out. A spectroscopic chemical probe of 1,1-diphenyl-2-picrylhydrazine (DPPHH) was employed to quantify the radicals in the IL-RM systems. The mechanism of the radical generation was also proposed. The DPPHH probe method is simple, rapid, and sensitive to quantify free radicals in the IL-RM systems. Finally, IL-RMs were successfully applied to degrade Rhodamine B (Rho-B) dye with low degradation cost, simple operation, short time consumption, and remarkable degradation effect. The results show a near 100% degradation rate for 10μmol·L-1 Rho-B in the IL-RMs system with pH 7.4 PBS containing 1mmol·L-1 chloroacetic acid as an aqueous phase.

Immobilization of simulated radioactive CsCl by hydrothermal synthesis for molten salt waste disposal

Immobilization of simulated radioactive CsCl by hydrothermal synthesis for molten salt waste disposal

Co-Motif-Engineered RuO2 Nanosheets for Robust and Efficient Acidic Oxygen Evolution.

The development of efficient and reliable acidic oxygen evolution reaction (OER) electrocatalysts represents a crucial step in the process of water electrolysis. RuO2, a benchmark OER catalyst, suffers from limited large-scale applicability due to its tendency toward the less stable lattice oxygen mechanism (LOM). This work reports the synthesis of Co-doped RuO2 nanosheets with a unique porous morphology composed of interconnected grains via a facile molten salt method. Co doping modulates the grain size, effectively increasing the specific surface area and introducing oxygen vacancies. These oxygen vacancies, coupled with the Co dopants, form Co-O(V) motifs that tune the electronic configuration of Ru. This structural engineering promotes a shift in the OER mechanism from the detrimental LOM pathway to the more efficient adsorbate evolution mechanism (AEM), significantly enhancing the stability of the RuO2 matrix in acidic environments. The optimized Co0.108-RuO2 catalyst exhibits a low overpotential of 214 mV at 10 mA cm-2 and remarkable stability over commercial RuO2 and undoped counterparts, owing to the synergistic effect of the increased surface area, Co-O(V) motifs, and favored AEM pathway. This strategy of utilizing Co doping to engineer morphology, electronic structure, and reaction mechanism offers a promising avenue for developing high-performance OER electrocatalysts.

A molten salt approach for synthesizing Mo2N nanoparticles embedded in N-doped mesoporous carbon as efficient hydrogen evolution electrocatalysts

A molten salt approach for synthesizing Mo2N nanoparticles embedded in N-doped mesoporous carbon as efficient hydrogen evolution electrocatalysts

Corrosion Behavior of Two Kinds of Stainless Steels in a Novel Ternary Nitrate/Nitrite Molten Salt

Corrosion Behavior of Two Kinds of Stainless Steels in a Novel Ternary Nitrate/Nitrite Molten Salt

Operation strategy of the heliostat field and receiver based on categorization of DNI fluctuation types

Transient changes in receiver heat are due to Direct Normal Irradiance (DNI) fluctuations, requiring operational strategies for receiver safety in cloudy weather. The effects of different operational strategies on the outlet temperature of molten salt and the tube wall temperature change rate were conducted by a 3D model. A strategy with heliostat field defocusing is recommended during long-time high fluctuations and moderate fluctuations with high dispersion. Under conditions of long-time moderate fluctuations with moderate and low dispersion and long-time low fluctuations, the rated outlet temperature set at 565 °C can meet the need. However, it is necessary to increase the molten salt flow before and after DNI ≤ 300 W/m2 to avoid too fast tube temperature change rate. According to the coefficient of variation (CV) during short-time DNI fluctuation, the strategy of heliostat defocusing (CV less than 50%) or rated outlet temperature (CV more than 50%) can be chosen. Combining the solar power tower (SPT) system model and cost model, the thermodynamic performance and economic analysis for systems with and without operational strategies were studied. With the operational strategy, the electricity generation was reduced by 3.39% compared to systems without any strategy. However, the lifetime of the receiver was increased, resulting in a 2.17% reduction in the Levelized Cost of Energy (LCOE).

Cooling Performance Experiment and Simulation Investigation of Flow Boiling Heat Transfer for Wire Rods during Quenching in Molten Salt Mixtures

When the wire is cooled in the salt bath, since the wire temperature far exceeds the boiling point of the molten salt, accurately modeling the heat transfer process in molten salt quenching is difficult. Therefore, for investigating the cooling mechanism and improving the mechanical properties of wire rods, quenching experiments are conducted on specimens (92Si) at various molten salt (a 1:1 mixture of NaNO3‐KNO3) temperatures using a salt bath furnace. Cooling curves are measured, and thus the real boiling heat transfer coefficient (HTC) at the metal–salt interface is calculated using a validated in‐house‐programmed inverse heat transfer algorithm based on experimental data. By integrating the experimentally determined boiling HTC with the convective HTC obtained from a salt bath simulation, a mathematical model of superposition flow boiling heat transfer is developed to predict the heat transfer characteristics, wire cooling behavior, and phase‐transformation processes within the salt bath, which is also an innovation point of this article. The model effectively captures the actual heat transfer behavior during the early stages of salt bath quenching. The model is further used to evaluate the optimal molten salt temperature for quenching in a modified salt bath system with a flow rate of 60 m3 h−1.

Novel processes for preparing high-purity anhydrous YCl3 and Mg-Y alloys

ABSTRACT The process for preparing high-purity anhydrous yttrium chloride was investigated using a complex salt containing an excess of yttrium oxychloride. By studying the conversion of yttrium oxychloride, it was determined that the key to preparing high-purity anhydrous yttrium chloride lay in the synergistic actions of gas-solid and solid-solid reactions. On this basis, a purity control strategy involving the adjustment of the height-diameter ratio of the sample was proposed to inhibit hydrolysis and enhance the conversion rate. By adopting the purity control strategy, high-purity anhydrous yttrium chloride with a yttrium oxychloride content below 0.1 wt.% was obtained at 600°C when the height-diameter ratio of the samples exceeded 1.42. Finally, the experiments on preparing Mg-Y alloys through molten salt electrolysis validated the impact of the YCl3 purity on the electrolysis process. When the high-purity anhydrous yttrium chloride obtained by this strategy was utilized, the current efficiency could reach 83.7%.

S-CO2 Brayton Cycle Coupled with Molten Salts Thermal Storage Energy, Exergy and Sizing Comparative Analysis

S-CO2 Brayton Cycle Coupled with Molten Salts Thermal Storage Energy, Exergy and Sizing Comparative Analysis

NaCl-Assisted electrospinning of bifunctional carbon fibers for High-Performance flexible zinc-air batteries.

NaCl-Assisted electrospinning of bifunctional carbon fibers for High-Performance flexible zinc-air batteries.

Selection of Sol-Gel Coatings by the Analytic Hierarchy Process and Life Cycle Assessment for Concentrated Solar Power Plants

Sol-gel coatings are commonly used to prevent corrosion from molten salt mixtures in CSP plants. Until now, they have been driven primarily by cost considerations, without integrating environmental criteria into the modeling and decision-making process. The novelty of this study lies in the development of an evaluation framework that incorporates environmental impact alongside technical and economic factors, providing a more sustainable approach. This work assesses porosity, thermal shock resistance, and thickness to determine the optimal sol-gel coating. For this purpose, the multi-criteria decision-making technique “Analytic Hierarchy Process” (AHP) and the Life Cycle Assessment (LCA) methodology are implemented. The results show that the scores obtained for the 3YSZ-5A (5% mol) coating are higher than those of the 3YSZ (3% mol) and 3YSZ-20A (20% mol) coatings, between 1.52 and 1.69, respectively. The 3YSZ-5A coating (5% mol) is the optimal solution among all the systems analyzed, with a score of 0.61 AHP pt. The coating of the same type and higher molar concentration (20%) achieved 0.55 AHP pt. Finally, the 3YSZ type coating received the lowest rating, with a score of 0.36 AHP pt. The insights generated in this research will support decision-making in the design and maintenance of CSP plants.

Corrosion effect by preferential formation of Cr and Fe-based ceramic compounds under NaCl–KCl–MgCl2 molten salts

Corrosion effect by preferential formation of Cr and Fe-based ceramic compounds under NaCl–KCl–MgCl2 molten salts

Molten Li Salt Modified Buried Interface Releases Strain and Realizes High Performance n-i-p Type CsPbI3 Perovskite Solar Cells.

Inorganic CsPbI3 perovskite solar cells (pero-SCs) have attracted great attention in photovoltaic research in recent years. Thermal annealing treatment is important for device optimization of the pero-SCs, nevertheless, traditional annealing process leads to residual strain owing to the difference of thermal expansion coefficients between perovskite active layer and SnO2 electron transporting layer (ETL) in n-i-p pero-SCs. Additionally, abundant defects and mismatched energy levels restrict the application of SnO2 as ETL in the CsPbI3 n-i-p pero-SCs. Here, by applying a molten mixture of Li salts during the fabrication of the ETL, the residual strain is eliminated and the energy level alignment is optimized. The molten salt (MS) treatment improves the quality of the SnO2 ETL, facilitates better crystallization of the perovskite active layer, and reduces lattice strain. As a result, the n-i-p pero-SCs based on CsPbI3 with SnO2 ETL show a notable increase in power conversion efficiency, from 17.46% for the device without the MS treatment to 20.49% for that with the MS treatment, and enhanced stability of the pero-SCs. This approach addresses key challenges in the pero-SCs, demonstrating that optimizing the interface between the ETL and perovskite active layer can greatly improve the photovoltaic performance of the CsPbI3-based n-i-p pero-SCs.

Insight to the Electro-Deposition of Sr and Cs to the Liquid Bi Electrode-A Model Development

Abstract The use of Bi electrode for the electrochemical separation of Sr and Cs is a promising method for separating radioactive nuclides. Because both the active electrode and molten salt system are in liquid form, the electrochemical reactions involve various physical changes, making the process complex and interdependent. By integrating the diffusion, electromigration, and phase transition, a transition model enabling real-time predictions of Sr and Cs separation in the molten salt was developed and validated by the experiments. Effect of values and modes of the applied current on the Sr and Cs deposition was examined. It was found that based on the laboratory-scale electrochemical reactions, applying a large current followed by a decreasing current facilitates the electrochemical separation of Sr and Cs.

A Hybrid Solar–Thermoelectric System Incorporating Molten Salt for Sustainable Energy Storage Solutions

Green sustainable energy, especially renewable energy, is gaining huge popularity and is considered a vital energy in addressing energy conservation and global climate change. One of the most significant renewable energy sources in the UAE is solar energy, due to the country’s high solar radiation levels. This paper focuses on advanced technology that integrates parabolic trough mirrors, molten salt storage, and thermoelectric generators (TEGs) to provide a reliable and effective solar system in the UAE. Furthermore, the new system can be manufactured in different sizes suitable for consumption whether in ordinary houses or commercial establishments and businesses. The proposed design theoretically achieves the target electrical energy of 2.067 kWh/day with 90% thermal efficiency, 90.2% optical efficiency, and 8% TEG efficiency that can be elevated to higher values reaching 149% using the liquid-saturated porous medium, ensuring the operation of the system throughout the day. This makes it a suitable solar system in off-grid areas. Moreover, this system is a cost-effective, carbon-free, and day-and-night energy source that can be dispatched on the electric grid like any fossil fuel plant under the proposed method, with less maintenance, thus contributing to the UAE’s renewable energy strategy.

Colloidal Chemistry in Molten Inorganic Salts: Direct Synthesis of III-V Quantum Dots via Dehalosilylation of (Me3Si)3Pn (Pn = P, As) with Group III Halides.

Gallium pnictides, such as GaAs and GaP, are among the most widely used semiconductors for electronic, optoelectronic, and photonic applications. However, solution syntheses of gallium pnictide nanomaterials are less developed than those of many other colloidal semiconductors, including indium pnictides, II-VI and IV-VI compounds, and lead halide perovskites. In this work, we demonstrate that the Wells dehalosilylation reaction can be carried out in molten inorganic salt solvents to synthesize colloidal GaAs, GaP, and GaP1-xAsx nanocrystals. We demonstrate that discrete colloidal nanocrystals can be nucleated and grown in a molten salt with control over their size and composition. Additionally, we found that reaction temperatures above 400 °C are crucial for annealing structural defects in GaAs nanocrystals. We also highlight the utility of the as-synthesized GaP nanocrystals by showing that GaP can be solution-processed into high-refractive-index coatings and patterned by direct optical lithography with micron resolution. Finally, we demonstrate that dehalosilylation reactions in molten salts can be generalized to synthesize indium pnictide (Pn = As, P) and ternary (In1-xGaxAs and In1-xGaxP) quantum dots.

Molten salts assisted synthesis of single crystalline NCM811 with surface modification for high energy density lithium-ion batteries

Molten salts assisted synthesis of single crystalline NCM811 with surface modification for high energy density lithium-ion batteries

Stable Molten Salts Mediated Growth of Single‐Crystalline LiNi0.8Co0.1Mn0.1O2 with High Voltage Tolerance

AbstractAs electronic devices rapidly iterate and power batteries continuously upgrade, the demand for cathode materials with high energy density is becoming increasingly stringent. This trend not only drives the development of high voltage cathode materials, but also imposes great challenges on their repair and regeneration toward enhanced battery performance. This study presents a stable eutectic molten salt approach, utilizing an optimized KCl‐LiCl‐LiOH system that effectively mitigates lithium volatilization at the elevated temperatures. Moreover, this system enables sufficient single‐crystal reconstruction of fractured polycrystalline cathodes, achieving high structural stability and voltage tolerance in the regenerated cathode without further modification. The regenerated cathode (R‐NCM) exhibits superior structural and electrochemical stability, retaining 81.7% of its capacity after 400 cycles at 1 C with a cutoff voltage of 4.5 V, compared to 51.5% capacity retention for commercial cathodes (C‐NCM) under the same conditions. Even under high‐rate cycling conditions at 5 C, R‐NCM still retains 88.3% of its capacity after 200 cycles. The findings highlight the potential of direct regeneration methods to fulfill the growing demand for high‐performance high voltage cathodes.

Unveiling the Microscopic Origin of Ion Transference Numbers in Molten Salt Systems: A Kinetic Theory Approach to an Accurate “Golden Rule”

Unveiling the Microscopic Origin of Ion Transference Numbers in Molten Salt Systems: A Kinetic Theory Approach to an Accurate “Golden Rule”