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Ageing study and modelling of a High Temperature PEM Fuel Cell (HT-PEMFC)

par Laurence Laffont - publié le , mis à jour le

Sylvain RIGAL’s thesis defense intitled "Étude du vieillissement et modélisation des piles à combustible PEM Hautes Températures (PEM-HT)" (Ageing study and modelling of a High Temperature PEM Fuel Cell (HT-PEMFC)) will be taking place on Thursday, December 20th 2020 at 10 am through visioconferencing.

Work for this thesis has been issued from the initiative projet FUCHYA, conducted by IRT Saint-Exupéry avec le LAPLACE, Safran et Airbus.

Zoom Link :
Participate :

Meeting ID : 957 2861 2589
Passcode : 640765

Jury :
Mr Yann BULTEL - Grenoble INP/LEPMI - Rapporteur
Mr Samir JEMEI - University of Franche-Comté/FEMTO-ST - Rapporteur
Mr Jacques ROZIÈRE University of Montpellier-II /ICGM - Reviewer
Ms Melika HINAJE - University of Lorraine/GREEN - Reviewer
Mr Christophe TURPIN - Toulouse INP - Thesis Supervisor
Mr Amine JAAFAR - Toulouse INP - Thesis co-Supervisor
Ms Marion SCOHY - Safran - Guest
Mr Théophile HORDÉ - Airbus - Guest
Mr Fabio COCCETTI - IRT Saint-Exupéry - Guest

Abstract :
As anthropogenic impacts have never been as heavy for the planet, "renewable" energies could make it possible to reduce the ecological impact linked to humanity’s energical needs. This is why hydrogen currently holds great hope as an energy carrier allowing the storage of electrical energy produced by intermittent "renewable" sources. The Fuel Cell (FC) then appears as a key element of this hydrogen economy.
Amongst FC technologies, the Proton Exchange Membrane FC (PEMFC) seems to generate the most researching efforts. It mainly comes into two sub-technologies : Low Temperature (LT-PEMFC), operating around 80 °C and High Temperature (HT-PEMFC) operating around 160 °C. LT-PEMFC has recently permeated the automobile market. Knowledge of the more recent HT-PEMFC technology is still far from that of LT-PEMFC.
The work presented in this manuscript was carried out at the Laboratory of Plasma and Conversion Energy (LAPLACE) which has been carrting studies on LT-PEMFC and LT-PEM electrolysers since the noughts. This thesis introduces the first works from LAPLACE concerning HT-PEMFC.
In this thesis, a map of the performances of a HT-PEMFC under different operating conditions is drawn up thanks to the conduction of a sensitivity study. During this study, three HT-PEMFC Membrane Electrode Assemblies (AMEs) models were characterized (via polarization curves, cyclic voltametry and electrochemical impedance spectroscopy) under different operating conditions : gas over-stoichiometry and functionning temperature. The resukts are that the HT-PEMFC technology seems to be first impacted by the temperature before over-stoichiometry (in the ranges of variations tested). In addition, this technology seems more conducive to the use of low over-stoichiometry of air and hydrogen than the LT-PEMFC technology.
The thesis uses a model developed at the LAPLACE initially for LT-PEMFC then adapted to the polarization curves from this sensitivity study. To do this, a multi-curve polarization and multi-operating method has been developed. This method seems to allow better decorrelation of certain parameters of the model by forcing other parameters to be common to several operating conditions. The model is also improved as so to take into account the impact of over-stoichiometry of air up on cell voltage. The impact of the reduction in the sensitivity study is also investigated as well as the impact of the degradation of the MEAs during the study.
The last aspect of HT-PEMFC studied in this manuscript is the behavior of this technology during constant current ageing tests in single-cell and multicellular stack. For this, seven AMEs were tested at different powers for more than 500 hours (for the most part). One of the tests, at a power density three times higher than that generally used in the literature as nominal power density, led to the lowest degradation rate. It is also illustrated during this work that the method of calculation of the degradating rate can lead to contradictory results. In addition, the characterization periods seem to have a strong impact upon the degradation, probably because of the high potentials explored which would cause corrosion of the carbon support of the active cathode layer. Finally, the test of a multicellular stack showed degradation rates twice as high as the single-cell tests.