Mg-based nanocomposites for hydrogen storage with additives containing Zr or Fe

Abstract

Hydrogen storage is an important subject of applied research, in order to make possible the use of H2 as a cleaner and renewable energy carrier. Some of the major recent advances in this field refer to the development of solid hydrogen tanks using metallic hydrides, in particular based on MgH2. This material presents as main advantages its high volumetric density of energy and the low cost of the starting metal. The preparation of MgH2 - based nanocomposites by high-energy ball milling (HEBM) promotes important improvements in the H-absorption/desorption kinetics at temperatures around 300 °C. In this proposal, different nanocomposites based on MgH2 will be prepared with additives containing Zr or Fe. Three types of materials will be considered: the metallic elements; compounds with the presence of fluorine; amorphous metal alloys. The additive that provides the best hydrogen storage properties will be selected for forthcoming tests with different compositions. Finally, the optimized mixture will be evaluated using cold rolling (CR) as a processing route, which has a significant cost advantage over HEBM. The microstructures and morphologies obtained will be evaluated by different techniques of structural characterization and correlated to the corresponding H2 storage properties. The evolution of the phases formed during the processing and during loading with hydrogen will be evaluated by X-ray diffraction (XRD). Morphological and distribution analyzes of the present phases will be performed by scanning electron microscopy (SEM). The H-absorption/desorption properties will be determined by differential scanning calorimetry (DSC) and kinetic measurements by the Sievert method. The analysis of the results should lead to the establishment of new correlations between structure, properties and processing of MgH2-based nanocomposites for hydrogen storage. (AU)