Molten Salt Electrolysis Research Articles

Facile preparation of metallic vanadium from consumable V2CO solid solution by molten salt electrolysis

A novel strategy for the preparation of metallic vanadium from V2CO solid solution as consumable anode is proposed by molten salt electrolysis. Controllable synthesis of V2CO solid solution was confirmed based on thermodynamic analysis and carbothermal reduction of V2O3. The constant-current electrolysis process of V2CO was divided into three stages, i.e. induction period (IP), initial depositional period (IDP), and reaction equilibrium period (REP). It was found that V2+ ions from V2CO anode were mainly dissolved into NaCl-KCl molten salts at lower anode current density than 0.2 A cm−2, and then was reduced on cathode. Meanwhile, CO was formed on anode. With the increase of anode current density, the concentrations of vanadium ions in molten salts were increased and induction period was shortened. In addition, particle size of metallic vanadium decreased with the increase of cathode current density. At all anode and cathode current density, metallic vanadium with high purity was obtained by molten salt electrolysis with consumable V2CO anode.

CO2‐Derived Oxygen‐Rich Carbon with Enhanced Redox Reactions as a Cathode Material for Aqueous Zn‐Ion Batteries

AbstractAqueous Zn‐ion batteries based on carbon cathode materials show high potential in the application of energy storage due to their low cost, high safety and long cycling lifespan, but the low reversible capacity and energy density hinder their practical. Herein, CO2‐derived oxygen‐rich carbons by molten salt electrolysis are proposed as attractive cathode materials with enhanced redox reactions. By optimizing the electrolysis current density at 50 mA cm−2, electrolytic carbon featuring honeycomb‐like morphology, high specific surface area and O content, as well as abundant defect is realized. Owing to the enhanced electrochemical reactions originating from the oxygen‐rich functional group in the electrolytic carbon, improved electrochemical Zn storage performance is achieved, showing a high capacity of 257 mAh g−1 at 0.05 A g−1, which is one of the highest values reported, and it preserves good cycling stability after 10000 cycles at 1 A g−1. It is revealed that C=O group in electrolytic carbon shows high reactivity and can reversibly storage and release Zn2+ ions, which is accompanied by the formation and dissolution of ZnxOTfy(OH)2x‐y⋅nH2O layer. This work offers effective strategy to improve the electrochemical performance of carbons by manipulating the surface reaction of carbon for aqueous Zn‐ion batteries.

In situ X-ray diffraction analysis of electrochemical Dy–Ni alloying in molten LiCl–KCl

In situ energy-dispersive X-ray diffraction was employed to investigate electrochemical Dy–Ni alloying in molten LiCl–KCl at 723 K. This enabled the determination of the crystal structures and orientations of the products formed during molten salt electrolysis, while also eliminating the effects of the post-electrolysis processes (such as cooling and washing) that are necessary in ex situ measurements. The diffraction peak intensities of DyNi2 generally increased during potentiostatic electrolysis at 0.50 V vs. Li+/Li, whereas the Ni diffraction peak intensities gradually decreased. Furthermore, the intensity of the X-ray fluorescence peak of Dy gradually increased. Thus, DyNi2 could be directly formed from Ni via electrolysis, as no diffraction peaks corresponding to materials other than Ni and DyNi2 were observed. Moreover, (022)-oriented DyNi2 grew preferentially on the (200)-oriented Ni substrate.

Electrochemical Reduction of Lead Sulphide in NaCl-KCl and NaCl-KCl-%2Na2S

In this study, the lead production from lead sulfide (PbS) by molten salt electrolysis was investigated under potentiostatic and galvanostatic conditions using NaCl-KCl and NaCl-KCl-2%Na2S electrolytes. Stable cell voltage and current were aimed with the addition of Na2S to the NaCl-KCl electrolyte. Reduction experiments were carried out at constant 700 °C temperature and for 15 min. duration. The current density was set to 250 mA/cm2 for the galvanostatic reduction experiments. It was observed that there was an increase in cell voltage in both electrolytes due to the decrease in the amount of PbS in galvanostatic experiments. In these experiments, it was determined that the reduction occurred at higher cell voltages in the NaCl-KCl electrolyte compared to the NaCl-KCl-2%Na2S electrolyte. Although the cell voltage was aimed to remain constant with the Na2S addition, the cell voltage decreased slightly compared to the NaCl-KCl electrolyte, but increased with the experiment duration as in the NaCl-KCl electrolyte. Potentiostatic reduction experiments carried out at a constant cell voltage of 3.0 V under the electrolyte decomposition voltage. The morphology of the cathode products was examined by SEM-EDS analysis and, the phases were examined by X-ray diffractometry. Higher current values were obtained in the NaCl-KCl-%2Na2S electrolyte compared to the NaCl-KCl electrolyte. Current variation with electrolysis duration showed similar trends in both electrolytes. According to structural characterization, it was determined that the metallic lead mass did not contain any impurities.

Separation of uranium from lanthanides (La, Sm) with sacrificial Li anode in LiCl-KCl eutectic salt

In the electrorefining process, the existence of cyclic electrolysis will lead to a low current efficiency. In order to eliminate the cyclic electrolysis, we explored a sacrificial Li metal anode for separating uranium (U) and lanthanides in this work. Electrochemical technique as well as electronic absorption spectroscopy (EAS) were employed to study the U species during the separation process. After potentiostatic deposition separation, the recovery efficiency of U reached 99%, and the main products were Al3U and Al4U. At the same time, the successful separation of U and lanthanides was achieved, and the separation factors for La and Sm were SFU/La = 2251, SFU/Sm = 4662, respectively. The results of EAS showed that both U and Sm remained in the lower valence states U(III) and Sm(II) during the separation process, indicating that the cyclic electrolysis was suppressed. Finally, the use of Li anode to suppress cyclic electrolysis has achieved a current efficiency of 93%. It is of great significance to improve current efficiency in the pyrochemical processing of spent nuclear fuel by molten salt electrolysis.

Electrolytic extraction of yttrium using recycle liquid gallium electrode from molten LiCl-KCl

To recover the rare earth element yttrium (Y) from spent fuel by molten salt electrolysis technology, the electrochemical redox mechanism of Y(III) and Ga(III) ions on tungsten electrode and the electrode reaction of Y(III) ions on the liquid Ga electrode were systematically detected by a series of electrochemical test methods, including cyclic voltammetry, square wave voltammetry and open circuit chronopotentiometry, etc. The thermodynamic and kinetic parameters of the electrode process on Ga(III) and Y(III) ions were obtained in this work. The measured diffusion activation energies (Ea) of electrode process for Y(III) and Ga(III) ions were calculated as 30.40 kJ·mol−1 and 33.33 kJ·mol−1. The electrodeposition process of Y and Ga was studied by CV and OCP, and thermodynamic parameters of Ga-Y alloys formed were also calculated. Thermodynamic parameters of Ga2Y intermetallic compounds were calculated based on open circuit chronopotentiometry at different temperatures (ΔHf0(Ga2Y)=-279.205kJmol-1 and ΔSf0(Ga2Y)=-123.9Jmol-1K-1). Yttrium was extracted by potentiostatic electrolysis and galvanostatic electrolysis on liquid Ga electrode in molten salts. In order to save the amount of liquid metal gallium, the best initial (2.5 g) was used. The cathodic deposition Products were characterized by X-ray diffraction analysis and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy. According to ICP-AES analysis, the extraction rate of Y on Ga electrode can reach a maximum of 99.39%.

Waste Eggshell-derived N, P, S Tri-doped Core-shell Catalysts for Efficient Fenton-like Catalysis

Heteroatom-doped carbon materials have been proved as potent catalysts for the remediation of organic contaminants. Herein, molten salt electrolysis (MSE) was employed to convert waste eggshell and Co3O4 into N, P, S tri-doped core–shell catalyst (Co@NPSC), achieving the conversion of waste eggshell into value-added materials. Impressively, Co@NPSC/peroxymonosulfate (PMS) system exhibited an exceptional ultra-high turnover frequency (TOF) value of 83.86 min−1 for sulfamethoxazole (SMX) degradation with a low catalyst dosage of 0.001 g L–1. Subsequently, density functional theory (DFT) simulation clarified the synergistic essences of catalytic oxidation (i.e., the Co@NPSC catalyst reduced the adsorption energy of PMS molecular on its surface, reduced itself work function, enhanced the length of the O-O bond (IO-O) of PMS molecule, and facilitated electron transfer for PMS activation). In addition, both theoretical predictions and acute toxicity assay results indicated that the degradation of SMX equals detoxification. This work provides a new insight into the reutilization of waste eggshell and the design of heteroatom-doped core–shell catalysts.

Electrolytic core–shell Co@C for diethyl phthalate degradation

• A high-value utilization strategy of CO 2 converted carbon materials was provided. • CO 2 was used as a feedstock to prepare Co@C catalyst. • Co@C was synthesized by the molten salt electrochemical conversion. • Co@C catalyst showed a high turnover frequency value of 2.28 min −1 . • DFT calculations identified the activation mechanism of PMS by Co@C. Greenhouse gases carbon dioxide (CO 2 ) can be converted into high value-added carbon materials by molten salt electrolysis. Herein, we employ CO 2 as the inorganic carbon source to prepare a core–shell catalyst (Co@C) by molten salt electrolysis for the activation of peroxymonosulfate (PMS) to degrade diethyl phthalate (DEP). The electrolytic Co@C catalyst presents a high catalytic performance for the degradation of DEP with a high turnover frequency (TOF) value (2.28 min −1 ), a relatively low catalyst dosage (Cat = 50 mg L –1 ), low oxidant concentration (PMS = 0.46 mM), a wide range of pH applicability (pH = 3–9), and low activation energy ( E a = 38.88 kJ mol −1 ). In addition, the Co leaching rate is low (<1 mg L –1 ) in the pH range of 5–11 and the total organic carbon (TOC) removal was reached 78.9% under the catalyst dosage was 50 mg L –1 . The DEP degradation pathways mainly involved ethyl formate elimination, ethoxy abstraction, carboxyl abstraction, decarboxylation, hydroxy abstraction, esterification and ring cleavage of DEP. Further, theoretical calculations confirm that Co nanoparticles (Co NPs) encapsulated with graphitized carbon shell derived from CO 2 reduce the work function (WF) of catalysts, enhance the length of bond O–O ( I O-O ) of PMS molecule, and facilitate the charge transfer from the catalysts to PMS molecule. This work provides a new insight into the utilization of CO 2 served as inorganic carbon sources and the design of heterogeneous catalysts.

Harvesting Si Nanostructures and C–Si Composites by Paired Electrolysis in Molten Salt: Implications for Lithium Storage

Harvesting Si Nanostructures and C–Si Composites by Paired Electrolysis in Molten Salt: Implications for Lithium Storage

Study on the Reaction Between Anodic Gas and Nd in Neodymium Oxide Molten Salt Electrolysis

Study on the Reaction Between Anodic Gas and Nd in Neodymium Oxide Molten Salt Electrolysis

Effect of Bubbles and Liquid Drops Fluid Dynamics on the Lithium Recombination inside a Lithium Electrolytic Cell with Diaphragm

Metallic lithium, which is a critical and strategic metal for the world’s production of energy storage devices, is mainly produced from molten salt electrolysis. To increase the efficiency of the process, it is of utmost importance to prevent lithium recombination during the process to avoid energy waste. This research studies the behavior of the main variables involved in the reaction inside a -production experimental cell from the mass transfer, electrochemical and fluid dynamics standpoints. Simulations were done for a total electrolysis time interval of 600 s using a turbulent (k-ε) approach to solve the two-phase flow coupled to the lithium electrolysis process. To analyze the influence of cathode fluid dynamics in relation to the amount of recombined lithium, two configurations of the diaphragm were evaluated including the incorporation of a baffle at the bottom of the cell and the inclination of the diaphragm. The baffle reduced the amount of recombined lithium by and the diaphragm with an inclination < 90° reduced the total recombined mass by although it increased the energy consumption by with respect to the base case of a vertical diaphragm.

Electrochemical Behavior of Sm(III) and Electrodeposition of Samarium from 1-Butyl-1-Methylpyrrolidinium Dicyanamide Ionic Liquid

Electrodeposition of rare-earth metals using ionic liquid is considered as a potential alternative to conventional high-temperature molten salt electrolysis. Herein, the electrochemical reduction of samarium(III) at near ambient conditions is investigated using different samarium precursors, namely, triflate (Sm(OTf)3), nitrate (Sm(NO3)3.6H2O) and chloride (SmCl3), in 1-butyl-1-methylpyrrolidinium dicyanamide ([BMP][DCA]) ionic liquid. FT-infrared and Raman spectroscopy analyses of Sm3+/[BMP][DCA] solutions confirm the coordination of Sm3+ species with ion through nitrogen atom. Cyclic voltammetry of Sm3+ at glassy carbon electrode provides evidence of a two-step reduction process in all the systems via Sm3+ to Sm2+ and Sm2+ to Sm0 with peaks observed at similar reduction potentials owing to indifference in samarium(III) chemistries in each medium which is supported by a plausible mechanism. The diffusion coefficient of Sm3+ in [BMP][DCA] was determined to be 3.00 × 10−7, 3.64 × 10−8 and 1.90 × 10−7 cm2.s−1 for Sm(OTf)3, Sm(NO3)3.6H2O and SmCl3 systems, respectively. The electrodeposition of samarium was achieved on nickel and glassy carbon substrates under two different potentials and temperatures. X-ray photoelectron spectroscopy confirms that the samarium electrodeposits are a mixture of metallic and oxide forms.

Basic Physical Properties of Aluminum Alloys and Their Electrolyte Systems Prepared by Molten Salt Electrolysis Using Black Aluminum Dross as Raw Material

Basic Physical Properties of Aluminum Alloys and Their Electrolyte Systems Prepared by Molten Salt Electrolysis Using Black Aluminum Dross as Raw Material

Corrosion Protection Oxide Scale Formed on Surface of Fe-Ni-M (M = Al, Cr, Cu) Inert Anode for Molten Salt Electrolysis.

An oxide scale formed on the surface of metal anodes is crucial for determining the overall quality of molten salt electrolysis (MSE), particularly for the durability of the anode materials. However, the material properties of oxide scales are yet to be revealed, particularly in ternary spinel oxide phases. Therefore, we investigate the mechanical and thermal properties of spinel oxides via first-principles calculations. The oxides are calculated using the models of normal (cubic) and inverse (orthorhombic) spinel compounds. The d-orbital exchange correlation potential of transition metal oxides is addressed using the generalized gradient approximation plus Hubbard U. The lattice constant, formation energy, cohesive energy, elastic modulus, Poisson’s ratio, universal anisotropy index, hardness, minimal thermal conductivity, and thermal expansion coefficient are calculated. Based on the calculated mechanical and thermal properties of the spinel compound, the Fe–Ni–Al inert anode is expected to be the most suitable oxide scale for MSE applications among the materials investigated in our study.

The formation mechanism and thermolelectric performance of CoSb3 skutterudite with tailored morphologies prepared by molten salt electrolysis

The electrolysis voltage strongly influences the morphology and thermoelectric performance of materials prepared by electrochemical synthesis. However, the nature of the reaction is not clear up to now. In this paper, skutterudite CoSb3 with different morphologies are synthesized by molten salt electrolysis at various electrolysis voltages, and the effect of electrolysis voltage on the morphology and thermoelectric performance of skutterudite CoSb3 are studied by comparing their SEM patterns as well as electrical conductivity, Seebeck coefficients and thermal conductivity. The electrical conductivities and Seebeck coefficients of the obtained CoSb3 were tested by a four-probe technique. The thermal conductivities were measured by a thermal diffusivity system using Pyroceram as a reference sample. It is found that the electrolysis voltage affects the morphology of the CoSb3 via influencing the relationship between the reaction and diffusion rates. The ZT values of the materials are dependent on their morphologies, grain size and the highest ZT value is 0.028 for petal-like aggregates.

Characterizations and growth kinetics of the borided layer formed on pure nickel by molten salt electrolysis

Molten salt electrolysis was applied for the boronizing of nickel with Na2B4O7?10H2O-Na2CO3 as the electrolyte and characterizations and the growth kinetics of borided layer is reported. The experiment was carried out in silicon carbide crucible at 1193 K, 1223 K, and 1243 K for 1 h, 2 h, 3 h, and 4 h. The morphology and phases formed on the surface of pure nickel were analyzed by means of scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and X-ray diffraction analysis (XRD). The surface hardness and corrosion resistance of the boronized sample were tested by micro hardness tester and electrochemical workstation, respectively. The borided layer was composed of nickel borides and its thickness ranged from 71 to 184 ?m. After 1 h of boronizing, the hardness of the silicon rich borides is 966 HK, which is a little lower than that of the nickel borides (992-1008 HK); the surface hardness reached 1755 HK after 4 h electrolysis. Electrochemical impedance spectroscopy analysis showed that the corrosion resistance of boronized sample is better than that of pure nickel. Borided layer growth kinetics was studied by analyzing the relationship between thickness of the borided layer and time by mathematical method. Then the diffusion coefficient constant of boron atom in nickel at 1193 K, 1223 K and 1243 K was calculated accordingly and an equation was obtained to estimate the thickness of the borided layer.

Electrochemical extraction kinetics of Nd on reactive electrodes

• Pyroprocessing technology is a promising technology for the reprocessing of spent fuel. • It is critical to pursue electrode materials with high An / Ln separation efficiency. • The electrochemical reduction of Nd 3+ on the W electrode is a two-step reduction process. • The kinetic properties of Nd 3+ on W, reactive electrodes were measured. • Cd was evaluated as a favorable electrode material for electrochemical extract ion of Nd. Pyroprocessing technology with molten salt electrolysis as the core is a promising technology for the reprocessing of spent fuel. In this work, the electrochemical reduction mechanism and kinetic properties of Nd 3+ on various electrodes (inert W and reactive Al, Ga, Bi, Cd, Zn, Pb, and Sn electrodes) were systematically investigated and compared in LiCl-KCl eutectic melts using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and Tafel techniques. The electrochemical reduction of Nd 3+ was a two-step process on the W electrode including Nd 3+ →Nd 2+ and Nd 2+ →Nd, while it became a one-step process involving three electrons on the reactive electrodes with obvious depolarization effects. Furthermore, the connections between the reduction potentials of Nd 3+ on these reactive cathodes and the formation energies of the electrode-rich alloy phases (Al 11 Nd 3 , Cd 11 Nd, Pb 3 Nd, Zn 17 Nd 2 , Ga 6 Nd, Sn 3 Nd, BiNd 2 ) were established. After evaluating the physicochemical, depolarization and kinetic properties of these reactive electrodes, liquid Cd was considered as the most favorable material for the electrochemical extraction of Nd. In addition, Al, Cd, and Bi are also promising candidates for An / Ln separation.

In Situ Synthesis of Titanium Carbide Coating on Foam Titanium by Molten Salt Electrolysis

In Situ Synthesis of Titanium Carbide Coating on Foam Titanium by Molten Salt Electrolysis

Controllable preparation of dual-phase VC-C through in-situ electroconversion for lithium storage

Transition metal carbides as promising electrode materials for lithium ions batteries (LIBs) have attracted wide attentions due to high conductivity and capacity. In this paper, dual-phase VC-C as anode materials of LIBs is designed and synthesized through green and controllable in-situ electroconversion from CO 2 and NaVO 3 in molten salt. Three products including dual-phase VC-C (VC–C), vanadium carbide doped by carbon (VC-DC) and carbon doped by vanadium carbide (C-DVC), are prepared by the effective regulation during molten salt electrolysis. It is confirmed that dual-phase VC-C as anode materials of LIBs exhibits the best charge/discharge performance and cycling stability. At current density of 0.1 A g −1 , the stable reversible capacity can reach to 652.3 mAh g −1 . Even at a high current density of 1.0 A g −1 , the reversible capacity maintains about 300 mAh g −1 after 600 cycles. The capacity retention is as high as 98.4%. The average capacity loss of per cycle is only 0.0027%. The dual-phase VC-C through sustainable electroconversion from CO 2 and NaVO 3 in molten salt is of good promising anode materials for LIBs.

Recycling alloy scrap and CO2 by paired molten salt electrolysis

Reclaiming valuable materials from retired alloys and CO2 in an eco-friendly and efficient manner is critically important to meet the urgent need for strategical metals and curb climate change.