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Том 61, № 5 (2025)
Equilibrium and Discharge Characteristics of a Single Cell of Hydrogen-Vanadium Battery with Electrolyte of Different Acidity
Аннотация
A single-unit of rechargeable power source, hydrogen-vanadium battery (Pt–C)H2 Nafion VO2+(C)), has been studied for various sulfuric-acid contents of the vanadium electrolyte (catholyte) in the range from 3 to 6 M for the total amount of sulfuric-acid residues and a total concentration of vanadium compounds of 1 M. For this range of compositions, the dependences of the cell voltage (OCV) and of the half-cell potentials (OCP) on the vanadyl-to-vanadate ratio in the electrolyte have been determined for the open-circuit regime while the voltage and potentials shifts have been measured for the current passage through the cell in both directions. Contributions of both half-cell the potentials as well as of their polarizations to the cell voltage have been found separately by means of an external reference electrode branched to the vanadium flow electrode via film-shaped Luggin capillary. Conductivity of the vanadium electrolyte has been measured in the course of charge-discharge cycling and its dependence on vanadyl-to-vanadate ratio for the series of electrolyte compositions has been determined. It was found for the high-current region that the maximal specific discharge power of the cell diminishes from 0.68 to 0.45 W/cm2 with increase of the catholyte acidity, as a consequence of the concentration polarizations of both the positive and the negative half-cells, with a higher relative contribution for the latter one. For the low-current region (±0.25 A/cm2) the voltage-current curves of both half-cells are linear. The slope (i. e. the polarization resistance) for the hydrogen half-cell increases with a growth of electrolyte acidity while it decreases for the vanadium half-cell. As a result, their sum (i. e. the total resistance of the cell) increases from 0.34 to 0.39 Ohm cm2 in the range of acidities studied.
Èlektrohimiâ. 2025;61(5):237-250
237-250
Special issue based on the reports at the 17th International Meeting “Fundamental and Applied Problems of Solid State Ionics” (Chernogolovka, June 16–23, 2024)
Investigation of the binary eutectic system (1–x)(LiClO4–KClO4)–xAl2O3 by combination light spectroscopy (CLS)
Аннотация
The physical and chemical properties of the eutectic system (0.76LiClO4–0.24KClO4) eut and its heterogeneous composites with nanosized aluminum oxide powder at different temperatures, phase states and concentrations of Al2O3 have been investigated by Raman spectroscopy, differential scanning calorimetry (DSC) and impedance spectroscopy. The addition of Al2O3 leads to an increase in ionic conductivity and a decrease in activation energy. It is shown by Raman spectroscopy that the addition of aluminum oxide leads to the formation of an amorphous phase due to the “destruction” of the crystalline phase of lithium perchlorate.
Èlektrohimiâ. 2025;61(5):251-259
251-259
Electrical conductivity of the polyvinyl alcohol – sodium rhodanide system
Аннотация
In this work, sodium-ionic polymer electrolytes based on polyvinyl alcohol (PVA) and sodium rhodanide (NaSCN) have been investigated as promising materials for energy storage devices. The main attention is paid to the study of the influence of NaSCN concentration on the ionic conductivity, phase transitions and structural changes of the system in the temperature range 293–373 K. The results of differential thermal analysis, spectroscopy and electrochemical impedance measurements are presented, which showed a significant increase in specific ionic conductivity at a concentration of 20 wt % NaSCN. NaSCN. An improvement in ionic transport is observed due to the breaking of hydrogen bonds in the polymer matrix and an increase in the amorphous phase of the polymer. Quantum chemical calculations demonstrated the influence of solvation and hydration on the properties of ions in the system, indicating a favourable interaction of sodium cations with OH-groups of PVA.
Èlektrohimiâ. 2025;61(5):260-270
260-270