Development of experimental methodologies for PEMFC cold starts
Résumé
As part of the France 2030 program, decarbonation of industry, and in particular the development of hydrogen in the automotive sector is one of the main objectives for reducing greenhouse gases [1]. Thus, the DURASYS-PAC project is born, supported by PEPRH2. Its purpose is to study the durability of Proton Exchange Membrane Fuel Cells (PEMFC) for heavy mobility. It targets a start-up inferior to 30 seconds, at temperatures as low as -30°C associated to a durability superior to 20000 hours [2]. This work focuses on the identification of degradation of PEMFC materials during cold starts. One aspect of this study is to carry out passive hydrothermal ageing, i.e. without fuel cell operation, in order to study degradation caused specifically by the effects of cold starts.To carry out passive hydrothermal ageing processes representative of stack conditions, systems controlling mechanical stress, humidity and temperature applied to a PEMFC have been developed. The first one is a cell enclosing a Membrane Electrode Assembly (MEA), subjected to controlled stress, regulated temperature, supplied with humidified nitrogen and connected to a potentiostat for Electrochemical Impedance Spectroscopy (EIS). The second one, shown in Figure 1, allows to simulate the mechanical compression of a cell. It is dedicated to cross-sectional observations of the MEA after placement in various environments.Cell characterisation methodologies are under development to follow the degradation of MEA materials and interfaces during ageing, such as morphological, mechanical, electrochemical and physico-chemical characterisations. As shown in Figure 2, EIS results can be related to membrane wetting at different humidities in the surrounding atmosphere. Differential Scanning Calorimetry (DSC) analysis allows to study the melting and crystallization of water. As well, microscopic cross-sectional observations show the interfaces of the MEA, while peeling will enable to study variations in the adhesion of the multilayers. Moreover, an X-ray tomography capsule is developed to perform in-situ ageing and to observe its consequences in three spatial dimensions with high resolution.The identification of degradation markers will then enable us to define mitigations adapted to the cold starts of a PEMFC.
Domaines
| Origine | Fichiers produits par l'(les) auteur(s) |
|---|---|
| Licence |