Solid Molten Salt Research Articles

Novel Fe trihalides solid molten salt-FeX3 (X = F, Cl, Br) via one-step method with low temperature as anodes of lithium-ion batteries

Cost-effective metal trihalides exhibiting high specific capacity hold significant promise as anodes in lithium-ion batteries (LIBs). Within this study, the spotlight falls on innovative anode materials, denoted as solid molten salts (SMS-FeX3, X = F, Cl, Br), which are synthesized through the utilization of transition metal trihalides. SMS-FeX3 anodes offer a range of advantages, including facile synthesis, environmental sustainability, and the electrochemical benefits stemming from the superior conductivity and electrochemical performance of solid molten salts. Leveraging the synergistic interaction between Fe trihalides (FeF3, FeCl3, FeBr3) and N-Methyl-2-Pyrrolidone (NMP), these SMS materials exhibit exceptional electrochemical performance and remarkable cycle stability. Furthermore, a comprehensive comparison among the three Fe trihalides underscores their distinct characteristics: SMS-FeF3 showcases a consistent Coulombic Efficiency of approximately 100 % throughout 400 cycles. SMS-FeCl3 stands out with an initial specific capacity of 1258 mAh/g at 100 mA g−1, sustaining at 900 mAh/g after 400 cycles. Meanwhile, SMS-FeBr3, serving as a comparative material, exhibits commendable rate performance even at 2000 mA g−1. These captivating and pioneering SMS-FeX3 anode materials offer a fresh perspective on the anode fabrication of LIBs, bearing exceptional promise for practical applications.

Novel supported low-temperature solid molten salt (SMS) anode materials for Li-ion batteries

The Solid Molten Salt-Fe2O3@Polypyrrole (SMS-Fe2O3@PPy) materials as anode electrode are successfully synthesized by a two-step method and applied for lithium-ion batteries (LIBs). The SMS-Fe2O3@PPy electrode is composed of Fe-based solid molten salt (SMS), PPy and octahedral Fe2O3 nanoparticles. Importantly, the introduction of PPy not only can provide a coating to suppress the volume expansion but also improve the electrical conductivity of the material. The elegant synergy effectively reduces the volume expansion of the material during the Li+ insertion/extraction process. As an anode for the LIBs, the SMS-Fe2O3@PPy electrode deliver reversible capacities of 1346 mAh/g at 100 mA g−1, good cycle stability of 1198 mAh/g even after 1000 cycles at 500 mA g−1 and excellent rate performance of 110 mAh/g even at 50 A g−1. It is found that the SMS can provide a large amount of LiH by combining with Li+ in the discharge process. The potential adsorption sites (site A and site B) from SMS were obtained by Density Functional theory (DFT) methods, and the attraction capacity of SMS to Li+ increased with the increasing of the number of electrons around SMS.All above unique advantages lead to a large specific capacity as well as excellent cycling stability, resulting in a considerable electrochemical performance. It can be seen from the excellent electrochemical performance of SMS-Fe2O3@PPy electrode that portends this will be a promising material for high-performance electrochemical devices.

High-temperature ultrafast welding creating favorable V2O5 and conductive agents interface for high specific energy thermal batteries

The high interfacial resistance between V 2 O 5 cathode materials and conductive agents (molten salt and super carbon) is one of the biggest issues that hinder the development of high specific energy thermal batteries. Designing fast Li + and e – transport channels in cathode electrodes is considered as an effect method to improve electrochemical performance. Hence, a high-temperature ultrafast welding is proposed to reduce V 2 O 5 /conductive agents interfacial resistance by reconstructing the transmission channels of Li + and e – in this paper. The experimental studies reveal the optimum ultrafast welding of 700 °C for 10 s, eliminating gap resistance of cathode electrodes induced by the melt of solid molten salt and rebuilding the more plentiful Li + and e – transport channels, further reducing the contact resistance and gap resistance. Therefore, the electrodes deliver a high specific capacity of 270.69 mAh g −1 and a high specific energy of 610.60 Wh kg −1 at 0.1 A cm −2 and 500 °C with a cut-off voltage of 1.6 V. The high-temperature ultrafast welding provides guidance to build Li + and e – transport channels of other cathode materials in thermal batteries.

A New Strategy for Designing Supported Low Temperature Solid Molten Salt as Anode Materials for Lithium Ion Batteries

A New Strategy for Designing Supported Low Temperature Solid Molten Salt as Anode Materials for Lithium Ion Batteries

Increasing interfacial infiltration between cathode materials and solid molten salt for high power thermal batteries

Interfacial infiltration between cathode materials and ionic conduction additive is a key factor for reducing contact resistance in thermal battery. And structure of cathode materials has a huge impact on interfacial infiltration. Hence, NiS2 with nano structure, globular micro-nano structure and three dimensional micro-nano hierarchical structure are synthesized and used as cathode materials of high power thermal battery. A sintering treatment similar to the hot-pressing of powder is used to improve the infiltration between cathode materials and solid molten salt. The pulse test results show that nano NiS2 electrode has minimum resistance, which means nanocrystallization is beneficial to improve interfacial infiltration. Further studies indicate that microvoid of micro-nano hierarchical structures is not filled by solid molten salt electrolyte, which obstructs transmission of electronic and Li+, and sintering treatment could improve interfacial infiltration. The nano NiS2 cathode has excellent specific capacity with 484.2 mAh g − 1 under 0.2 A cm−2 after sintering treatment, which is higher than 431.7 mAh g − 1 of globular micro-nano NiS2 and 271.2 mAh g − 1 of three dimensional micro-nano NiS2 cathodes. The discharge results further show that hierarchical structures do not apply to the high power thermal battery based on non-flowing character of molten salt under the natural condition.

A novel process for preparing molten salt/expanded graphite composite phase change blocks with good uniformity and small volume expansion

Herein a novel process was explored for preparing molten salt/expanded graphite (EG) composite phase change material (PCM) blocks, which involves mixing a solid molten salt with EG thoroughly, compressing the mixture into a block with a designed shape and then heating the block to a temperature above the melting point of the molten salt followed by cooling. An MgCl2-KCl eutectic salt was used as the PCM, and its EG-based composite PCM block was prepared by this process, in which the optimal mass fraction of the eutectic was determined to be around 85%. The microstructure of the MgCl2-KCl/EG composite PCM block containing 85% the eutectic shows a uniform distribution of the molten salt. The composite PCM block has a melting point of 424.14°C and a solidification point of 418.39°C, and its latent heat values are 161.37J/g for melting and 160.28J/g for solidification. Compared with the eutectic salt, the composite PCM block exhibits a reduction in supercooling by 3.7°C and an enhancement in thermal conductivity by 11-fold. It has been verified that the composite PCM block possesses excellent thermal reliability. Furthermore, the composite PCM block has been compared with the one prepared by the conventional method (first adsorption and then compression). It is found that the composite PCM block fabricated by the novel process exhibits better uniformity and smaller volume expansion than the one obtained from the conventional method. The MgCl2-KCl/EG composite block shows great promise in high-temperature thermal energy storage systems, and this novel process is very suitable for preparing molten salt/EG composite PCM blocks.

Porous Magnesia Fibers as an Immobilizing Agent for Molten Salt in Thermal Batteries

In this work porous MgO fibers were investigated as an immobilizing agent in the solid molten salt electrolytes for thermal batteries. Their distribution, uniformity and electrochemical performance were characterized. Compared with ball-milling method, the use of liquid nitrogen as mixing medium resulted in an homogeneous distribution of molten salt particles on the surface of porous MgO fibers. The ionic conductivity of the separator using porous MgO fibers as an immobilizing agent is slightly higher than that of the separator when MgO powders were used as the immobilizing agent. Moreover, the discharge specific capacity of the battery using the porous MgO fibers, 564.39 mAh·g−1, is significantly greater than that of the battery using MgO powders, 355.67 mAh·g−1. More importantly, the electrolyte leakage content of the separator based on porous MgO fibers is also the lowest. Porous MgO fibers offer promising application in thermal batteries.

Morphology and Magnetic Properties of NiCuZn Ferrite Synthesized by Solid-Molten Salt Method

Cu doped NiCuZn ferrite Ni0.4-xCuxZn0.6Fe2O4 (x=0.16~0.28) have been prepared by the solid-molten salt method using NaCl as flux. The structure and properties were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM) and vibrating sample magnetometer (VSM) techniques. It is found that addition of Cu2+ results in the particles size growing up because of the tend of crystal structure to be a normal Zn ferrite.The Ms values of NCZF are decrease gradually with increasing of Cu content. Curie temperature (Tc) increases with Cu2+ content in the range of x<0.20, and then decreasing rapidly. This can be ascribed to that the lower magnetization moment Cu2+ ion amount of B-site increasing leads to weaker super-exchange effect.

Immersed particles of a multiphase reacting flow with chemical decomposition in the stokes flow regime

This paper examines the transient chemical decomposition of solid particles in a multiphase flow consisting of molten and gaseous phases at high temperature and low Reynolds number. The mass, energy, momentum and chemical reaction equations are solved for a particle immersed in a viscous flow of uniform properties. Numerical solutions are obtained and the results are validated with experimental data of samples involving the chemical decomposition of the mixture of CuO and CuCl2 particles in a molten salt. The analysis provides new insight into the implications of the rate of reaction vs. heat and mass transfer in a complex gas–solid–molten salt multiphase reacting system, as well as the impact on hydrogen yield in the thermochemical copper–chlorine (Cu–Cl) cycle of hydrogen generation.

A novel approach to the synthesis of a non‐toxic, platy pigment for anticorrosive paints

PurposeTo develop a method for the preparation of micaceous zinc ferrite (MZF), anticorrosive pigment having desirable chemical and physical properties.Design/methodology/approachMZF pigment was prepared after firing the oxidised solid molten salts without washing. The MZF pigment obtained was characterised using X‐ray diffraction analysis, crystal size analysis, scanning electron microscope and energy dispersive X‐ray analysis. The pigment obtained was also evaluated chemically with respect to moisture content, content of water‐soluble salts, hydrogen ion concentration (pH) and weight loss; and physically with respect to particle shape, colour, specific gravity and oil absorption. Commercially available micaceous iron oxide and zinc ferrite pigments were also characterised in comparison.FindingsA spinel, MZF pigment was prepared using relevant oxidised solid molten salts. The preparation produced a lamellar structure with a basic nature giving not only barrier protection but also chemical passivation of the substrate.Research limitations/implicationsThe anticorrosive properties of the pigments obtained could be evaluated using more conventional methods such as salt‐spray test.Practical implicationsThe pigment prepared could be used as a highly efficient pigment for anticorrosion coating for steel.Originality/valueThe method for the preparation of MZF pigment was novel. The pigment obtained could be used in various resin systems to produce anticorrosive paints for steel protection.

Further notes on sampling analysis, with application to coal

Herein a novel process was explored for preparing molten salt/expanded graphite (EG) composite phase change material (PCM) blocks, which involves mixing a solid molten salt with EG thoroughly, compressing the mixture into a block with a designed shape and then heating the block to a temperature above the melting point of the molten salt followed by cooling. An MgCl2-KCl eutectic salt was used as the PCM, and its EG-based composite PCM block was prepared by this process, in which the optimal mass fraction of the eutectic was determined to be around 85%. The microstructure of the MgCl2-KCl/EG composite PCM block containing 85% the eutectic shows a uniform distribution of the molten salt. The composite PCM block has a melting point of 424.14 °C and a solidification point of 418.39 °C, and its latent heat values are 161.37 J/g for melting and 160.28 J/g for solidification. Compared with the eutectic salt, the composite PCM block exhibits a reduction in supercooling by 3.7 °C and an enhancement in thermal conductivity by 11-fold. It has been verified that the composite PCM block possesses excellent thermal reliability. Furthermore, the composite PCM block has been compared with the one prepared by the conventional method (first adsorption and then compression). It is found that the composite PCM block fabricated by the novel process exhibits better uniformity and smaller volume expansion than the one obtained from the conventional method. The MgCl2-KCl/EG composite block shows great promise in high-temperature thermal energy storage systems, and this novel process is very suitable for preparing molten salt/EG composite PCM blocks.