Institute of High Temperature Electrochemistry

Muon-catalyzed fusion occurs with wave effects of varying duration. The aim of this study is to determine the response of the electron system of helium atoms and molecules to muon absorption. Due to electron–phonon coupling, perturbations in the form of oscillations of the electron system generate vibrations of the atoms. The fundamental frequency of the damped oscillations of the electron system of a helium atom fused with a muon is 8.265 × 1016 s–1. The spectral density of the oscillations of electronic states of a mesomolecule consisting of a helium atom and a muon is represented as a peak in the frequency dependence. Muon capture by a helium molecule leads to beats with an oscillation frequency of ~2 × 1012 s–1 commensurable with the frequency corresponding to the heat transfer mode.

Development of lithium all-solid-state power sources is a topical area of research worldwide. In order to solve the problem of high resistance at the cathode|solid electrolyte interface, it is proposed to introduce lithium-conducting glass 65Li2O·27B2O3·8SiO2 into the cathode material. Using X-ray diffraction and DSC data, it was established that there is no interaction between the cathode, sintering additive, and solid electrolyte up to 670°C. The introduction of 5 wt % glass followed by heat treatment resulted in a decrease in the resistance at the interface between cathode and solid electrolyte from 45 kOhm cm2 at 300°C to ~0.8 and 0.1 kOhm cm2 at 200 and 300°C, respectively. The charge-discharge process of all-solid-state power source is possible up to a current density of 100 μA/cm2 at a temperature of 200°C. Long-term cycling of the cell at a current density of 20 μA/cm2 at 200°C shows no deterioration in performance during the first 10 cycles.

This study theoretically evaluates the thermophysical properties of high-entropy molten salt mixtures composed of lithium, sodium, and potassium fluorides and chlorides, exhibiting enhanced thermodynamic stability as a result of the high configurational entropy. The equimolar mixture, , maximizes configurational entropy. This mixture's configurational entropy ( = 13.21 J mol-1 K-1) approaches the high-entropy threshold of Rln5 (13.38 J mol-1 K-1). These high-entropy mixtures, with entropy significantly exceeding that of FLiNaK (6.9 J mol-1 K-1), are promising coolants for molten salt reactors due to improved thermodynamic stability. Two eutectic compositions with reduced lithium content, derived from the phase diagram (melting points 606 and 630 °C), are also analyzed. Density, heat capacity, thermal conductivity, and viscosity are calculated from liquidus to 1000 °C using phenomenological superposition-extrapolation, thermodynamic perturbation theory (TPT), and molecular dynamics with machine learning interatomic potentials (MLIPs).

(100–x) Li2ZrO3–x 65Li2O · 27B2O3 · 8SiO2 (x = 1–8 wt. %) composites have been prepared. Relative density of the composites is shown to be higher than that of the sintered Li2ZrO3. According to the X-ray diffraction analysis, the formation of an impurity phase is observed at x of 8 wt. %, while other samples demonstrate peaks corresponding to monoclinic Li2ZrO3. Conductivity studies reveal that the application of the lithium borosilicate glass as sintering additives increases the total conductivity from ~ 10–7 to ~ 10–5 S · cm–1. The Li | 94Li2ZrO3–6LBS|Li electrochemical cell has been tested for the stability against molten lithium at 250 °C for 336 h and superior stability of the composite has been proven. Based on the obtained results, the 94Li2ZrO3–6LBS composite can be recommended for application in lithium batteries.

The experimental study of the formation/growth processes of crystals with Na0.74WO3 isostructural formula during potentiostatic electrolysis of 0.8Na2WO4–0.2WO3 and 0.9Na2WO4–0.1WO3 melts at 973 and 1023 K is performed. A mathematical model is proposed to describe the complex process mechanism, including the electroreduction of polytungstate anions [WnO3n+1]2– on the Pt cathode surface to [WnO3n]–, as well as the electrochemical and chemical reactions of Na+ with [WnO3n+1]2– and [WnO3n]–, respectively, on the crystal surface. The model considers the change in the concentration of lower reduced forms in the near-electrode layer, the ohmic drop in the melt, the mixed control of deposit growth, and the evolution of the new phase surface area and volume during the process. Exchange currents for electrochemical reactions, rate constants for reactions associated with deposit growth, surface concentration of lower reduced forms, formation time, and number density of nuclei are found from fitting chronoamperograms using this model. It is detected that the chemical reaction promotes the growth of crystals, while the electrochemical reaction leads to their electrodissolution under the studied conditions. The rates of forward and backward chemical reactions decrease as the temperature and the WO3 mole fraction in the melt decrease, respectively, while the kinetics of the electrochemical reaction depends weakly on these factors. The calculated crystal sizes and their numbers are in good agreement with the experimental ones. The proposed approaches to modeling are important for the development of technologies for the electrochemical synthesis of cubic NaxWO3.

Improving the efficiency of solid oxide electrolyzers is important for various industries, including chemical, energy, and mechanical engineering. This paper examines the influence of the design of solid oxide electrolyzer current leads on improving its exergy efficiency. For this purpose, mathematical modeling carried out to assess the effect of changes in design characteristics (such as the area of the reaction surface and channel edges) for a solid oxide electrolyzer of a planar design on its performance indicators. The relationship between changes in the trajectories of the current lead gas channels and voltage losses during operation of the electrochemical device, as well as their impact on the exergy efficiency of the electrolyzer, was established.