"Novel Li-N-metal hydride based materials for hydrogen storage"
Antonio Santoru / Early Stage Researcher at the Helmholtz Zentrum in Geesthacht, Germany
Working title of thesis
Novel Li-N metal hydride based materials for hydrogen storage.
Mixture of Amides and Hydrides are very promising materials for hydrogen storage. In particular the 2LiH-Mg(NH2)2 systems shows a theoretical hydrogen desorption temperature suitable for on-board power supply. Unfortunately the thermodynamic equilibrium state was not reached in suitable times because of the too high kinetic barrier. The best additive up to now is KH, and the phases involved in the kinetic process are relatively new and interesting materials. Understanding the synthesis mechanism of these new K/Mg-based phases and the investigation of the desorption kinetics in new amides-hydride systems is my main short-term target.
Nevertheless other new Li-N based systems can be synthesized combining LiH with HN-containing phases or molecules (amides, amines…). There is enough space in the chemistry of these new compounds to obtain new desorption pathways. Moreover, other hydrides than LiH can be combined and tested with amides phases, for example borohydrides, in order to obtain Reactive Composites. However the results reported so far for these systems were promising in terms of high gravimetric capacity and low desorption temperatures, but no system was proved to be reversible due to the formation of phases containing stable B-N bonds which is a strong limitation for practical use in mobile applications.
Tasks and methodology
For the synthesis and investigation of these systems I would like to gain confidence with some of the more advanced techniques (experimental method, data treatment and interpretation of the results): Ball Milling under high pressure of gas (HP-BM), In Situ X-Ray Diffraction (XRD) and neutron diffraction, Raman Spectroscopy, Mass Spectrometer-coupled desorption measurements (MS), Calorimetric Analyses (DSC and HP-DSC) thermogravimetric and differential thermal analyses (TG-DTA).
Antonio Santoru was born in Sassari on the 14/09/88. He obtained the Degree in Chemistry (3 years duration) and in Chemical Sciences (2 year duration) under the supervision of Prof. Stefano Enzo in October 2011 and in October 2013 respectively.
Topic of the thesis were the “Quantitative XRD analysis of fly ashes and powders from desulfurization process of carbon and oil power plants” and “Synthesis, characterization and reaction kinetics of potassium/magnesium based amide systems for hydrogen storage. During these experiences some skills and competences were developed like the synthesis of new materials and control of solid-solid and solid-gas reactions by mechanochemical or thermal processes under inert or reactive atmosphere; structural characterization by In-Situ Synchrotron Powder X-Ray Diffraction and Ex-Situ Powder X-Ray Diffraction; quantitative analysis and structural properties determination by Rietveld refinement; evaluation of thermal properties and by calorimetric methods (High-Pressure DSC); evaluation of the gas desorption properties in hydrogen storage functional materials (amides) by manometric (Sievert apparatus) and mass spectrometer measurements.