Home > Publications database > Mechanische Eigenschaften von katalysatorbeschichteten Membranen für die Polymer-Elektrolyt-Membran Elektrolyse |
Book/Dissertation / PhD Thesis | FZJ-2021-01789 |
2021
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag
Jülich
ISBN: 978-3-95806-533-8
Please use a persistent id in citations: http://hdl.handle.net/2128/27671 urn:nbn:de:0001-2021051014
Abstract: With the aim of substituting fossil fuels, the expansion of renewable electricity generation in Germany hasbeen strongly promoted in recent years. Due to weather conditions, electricity from wind and solar poweris subject to high fluctuation, so it is necessary to develop efficient storage options for electricity. One possibility is to store electricity in the form of hydrogen, which is generated by the electrolysis technology from renewable electricity. The polymer electrolyte membrane electrolysis is particularly suitable for this purpose. It works dynamically and can react quickly to the fluctuating input power. At present, this technology is still being worked on in terms of cost reduction, increased efficiency and longevity. Inparticular, the optimization of the catalyst coated membrane, typically Nafion$^{©}$ with iridium on the anode side and platinum on the cathode side, offers the potential to provide an improvement in these three areas. With regard to the mechanical properties, however, there is hardly any understanding so far. The aim of this work is therefore to analyze the mechanical properties of catalyst coated membranes and then to investigate the influence of these mechanical properties on cell performance. The work is divided into two parts: ex-situ and in-situ experiments. To investigate the relevant mechanical properties of catalyst coated membranes, ex-situ compression tests, swelling tests, stress relaxation experiments and creep tests under electrolysis conditions and under compression were carried out. For the in situ experiments, a pressure cell was developed with which it was possible to transfer clamping pressure via a stamp directly to the active cell area. In addition, different cell designs could be compared. The ex situ experiments showed a viscoelastic behavior for Nafion$^{©}$ and catalyst coated Nafion$^{©}$ under electrolysis conditions. The viscosity of catalyst coated membranes is 38 % lower. In the in situ experiments it could subsequently be proved that these viscoelastic properties have an influence on the cell performance. Due to the compression of the membrane, a loss of water occurs, which results in the performance being reduced above an optimum clamping pressure of 2.5 MPa. The time dependence of the compression after a pressure change, the swelling pressure and the stress relaxation also lead to a change in clamping pressure and thus performance over time. By constructive solutions clamping pressure must be kept constant in the cell.
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