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Title: Polymer-hydride nanocomposites for portable hydrogen storage
Author: Ploszajski, Anna
ISNI:       0000 0004 7229 3738
Awarding Body: UCL (University College London)
Current Institution: University College London (University of London)
Date of Award: 2018
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It has been nearly fifty years since the idea of the hydrogen economy – an energy landscape centred on hydrogen as the energy vector – was proposed. A major difficulty in realising the hydrogen economy has been hydrogen storage, particularly for the portable applications for which this energy-dense fuel is so attractive. For these applications, solid-state approaches to hydrogen storage are a good alternative to gas cylinders, from a volumetric and weight perspective. This thesis focuses on one particular material; a composite made from ammonia borane and polyethylene oxide (AB-PEO). A major finding from this project was that the ABPEO material is a cocrystal-forming system, the first to be recognised as a hydrogen storage material. The kinetics and mechanism of formation of the cocrystal phase have been investigated. The molecular structure of an AB-PEO cocrystal polymorph has been ascertained, and this experimentally proved what was only previously computationally predicted; that hydrogen bonds form between AB and PEO. These hydrogen bonds have been found to encourage hydrogen release from the AB molecules by promoting the formation of key reaction intermediates when the material is heated. This modification of the hydrogen release pathway results in lower hydrogen release temperatures but an increase in the levels of volatile gaseous impurities released alongside the hydrogen. However, a major beneficial effect of PEO on AB is the suppression of the bubbling and foaming which usually accompanies hydrogen release from AB. In this work, advanced time-resolved 3D imaging techniques have been used to observe and quantify the microstructural pore dynamics during hydrogen release from pellets made from AB-PEO composites. These experiments, never before used in the context of hydrogen storage, provide key insights to allow materials engineers to manufacture solid-state hydrogen storage materials into working portable systems.
Supervisor: Skipper, N. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available