Papers by Author: Thomáš Fabián

Abstract: Hydrogen is suggested as a promising fuel of the near future for the utilization in automotive and mobile applications. Therefore, safe and effective hydrogen storage systems need to be developed. One of the possibilities, suitable especially for mobile applications, is the storage of hydrogen in the form of light-metal hydrides. In this work we studied microstructure and hydrogen absorption and desorption kinetics in selected Mg-Ni alloys. Hydrogen saturation was carried out by the cathodic polarization in alkaline water-based solution. It was confirmed that hydrogen could be stored in the Mg2Ni intermetallic phase forming Mg2NiH0.3 phase using this technology. MgH2 hydride is also formed when the temperature of 90 °C is applied. The total content of hydrogen in the material after saturation is approx. 0.7 wt. % according to the thermogravimetry analysis. This low value is caused probably by the surface oxidation, blocking further hydrogen diffusion. Thermal hydrogen desorption tests showed that the Mg2NiH0.3 phase is able to release hydrogen even at temperatures lower than 100 °C.

Abstract: Hydrogen is the promising pollutant-free fuel of the near future. For various hydrogen applications, suitable storage systems have to be developed. One of the safe ways is the reversible storage of hydrogen in the form of light metal (lithium or magnesium) hydrides. MgH2 magnesium hydride shows very high storage capacity (approx. 7 wt. %), but its problem is high thermodynamic stability. Therefore, high temperature (over 400°C) is necessary for MgH2 to decompose producing hydrogen. The solution of this problem can be the utilization of the complex magnesium hydrides containing nickel, copper or other transition metals. In this work, the microstructure and hydrogen storage properties of the various magnesium alloys (Mg-Ni, Mg-Zn, Mg-Cu and Mg-Cu-Al) are described. The aim was to find suitable hydrogen storage system with good storage capacity and sufficient rate of formation and decomposition of hydrides. Microstructure, chemical and phase composition of the alloys were determined by the light and scanning electron microscopy, EDS and XRD. Hydrogen saturation was carried out by cathodic polarization in the alkaline solution. Hydrogen content in the material was estimated by XRD from the shift of the diffraction lines of present phases.