Hack, Jennifer;
(2021)
Multiscale Characterisation of Polymer Electrolyte Fuel Cells.
Doctoral thesis (Ph.D), UCL (University College London).
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Abstract
With the need to decarbonize comes the shift from fossil fuels to alternative sources of electricity generation. Polymer electrolyte fuel cells (PEFCs) are considered one of the promising alternative energy technologies, with applications from transport to stationary power. The materials inside PEFCs are intrinsically linked to their performance and the processes within them occur across multiple length- and timescales. Furthermore, current challenges for the design and performance of PEFCs include issues with water management, the durability of materials and degradation of electrochemical performance. In recent years, X ray and neutron imaging techniques have been emerging as key tools for characterizing the structure and morphology of fuel cells across length and time scales. With this in mind, this thesis describes the work undertaken to carry out multiscale characterization of PEFCs, from macro to nanoscale and from their beginning to end-of-life performance. Using a toolbox of both electrochemical and imaging techniques the work aims to develop methods for correlating the structure and morphology of features of the PEFC to their performance and degradation. For operando and in-situ imaging, bespoke fuel cells are designed to suit imaging requirements. Firstly, work at the macroscale is carried out. The use of (as yet unreported) operando neutron tomography showed that flow field geometry affects water distribution and fuel cell performance. Secondly, X ray computed tomography (X ray CT) was used to carry out microscale ex situ and in situ studies. Results showed that whilst ex situ imaging allows for optimisation of imaging parameters, a more in depth understanding of degradation mechanisms is afforded using in situ imaging. In situ work allowed for visualisation of the morphological mechanisms for inhomogeneous degradation across the MEA, by way of crack growth and propagation. The findings of this work are expected to provide guidance for the engineering of the next generation of PEFC materials and technologies.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | Multiscale Characterisation of Polymer Electrolyte Fuel Cells |
| Event: | UCL (University College London) |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | Copyright © The Author 2021. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request. |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Chemical Engineering |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10120865 |
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