Hydrogen storage in Mg-Ti thin film alloys: An in situ characterization study

Van Son Media, Son, 2009. – 154 p. – ISBN: 978-90-386-1632-2.Based on the weight constraints for on-board hydrogen storage systems, most of the elements are not particularly suitable as effective hydrogen storage medium. Hence, only the lightweight elements that can store a significant amount of hydrogen are of prime interest. Also, the phase of the hydride is important as it has a profound effect on the volumetric capacity. For example, CH₄ is a gas at ambient temperatures, which will lower the volumetric capacity significantly as compared to storing hydrogen in a solid. In this respect, Mg is one of the most promising elements as it exhibits a high gravimetric storage capacity of 7.7 wt.% of hydrogen and a high volumetric capacity of 110 kg/m³. In spite of its excellent storage capacity, the high desorption temperature (279 °C) and extremely slow hydrogen sorption kinetics prevent Mg from being employed commercially. It is generally accepted that the formation of a MgH₂ layer blocks further hydrogen diffusion, effectively decreasing the high storage capacity. Large scale application of metal hydrides as solid state hydrogen storage medium for the hydrogen economy is by no means the only possibility to commercialize metal hydrides.
From the Table of Contents
Introduction
The hydrogen economy
Other applications of metal hydrides
Recent progress in Mg-based alloys
Scope
Experimental
Thin film deposition and characterization
Electrochemical characterization
The electrochemical setup
Galvanostatic control
GITT charging and discharging
Amperometry and cyclic voltammetry
Electrochemical impedance spectroscopy
X-ray Diffraction
Grain size
Texture formation
In situ electrochemical X-ray diffraction
Hydrogen storage in Pd thin films
Results & discussion
Thermodynamics of Pd hydride thin film electrodes
Kinetics of Pd hydride thin film electrodes
Electrochemical hydrogen storage in thin film Mg_yTi_1-y alloys
Results & discussion
Structural characterization of the as-prepared thin films
Galvanostatic (dis)charging behavior
Thermodynamics and kinetics
Effects of the deposition technique
In situ XRD study of Mg_yTi_1-y alloys
Results & discussion
Structural characterization via in situ XRD gas loading
Structural characterization using in situ electrochemical XRD
Hydrogen storage in ternary MgTiX alloys
Results & discussion
The Miedema model
Thermodynamics of MgTiX hydride thin film electrodes