卷 61, 编号 5 (2025)

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.

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.