Abstract
This paper presents a study of the carbon support corrosion and mitigation strategies through the use of a pseudo-3D model. This model consists in coupling a 2D model along the channel with another model perpendicular to the flow at the rib/channel scale. Simulations offer a deeper understanding of the corrosion through the analysis of the local conditions. Rib/channel heterogeneities show the higher degradation in the zones facing the anodic rib. These results are validated qualitatively on literature data by analysis of SEM images and carbon dioxide concentration at the cathode outlet. Three mitigation strategies are studied using the model. The first one consists in speeding up the hydrogen filling of the cell. The second strategy involves an external electrical resistance to create a current leak during the startup. Third, a design study of the rib/channel is performed to minimize the cathode degradation. Whatever the mitigation strategy, it consists in reducing either the duration or the magnitude of the high cathode electrode potential.
Highlights
For automotive application, the durability of fuel cells has to be improved
Current proton exchange membrane fuel cells (PEMFC) lifetime is around 4000 h, when 5000 h are expected for vehicle application [1]
When the H2 front arrives at the anode outlet, hydrogen reaches first the anode catalyst layer in front of the channel while its diffusion under the rib is delayed, so a small cathode potential heterogeneity is induced with a higher potential in the area facing the anode rib and a lower potential in the area facing the anode gas channel
Summary
The durability of fuel cells has to be improved. Current proton exchange membrane fuel cells (PEMFC) lifetime is around 4000 h, when 5000 h are expected for vehicle application [1]. The cell is discretized into twenty sections considering a 1D generic electrode model This 1D model accounts for the complex electrochemical mechanism, including surface platinum reduction/oxidation as well as two carbon oxidation reactions. The development of mitigation strategies through system controls may limit the carbon corrosion during startup and shutdown. An auxiliary load allows mitigating the degradation by hindering the decrease of electro-chemical surface area (ECSA) [24,25] This latter strategy limits the high potential achieved by the cathode and mitigates the carbon corrosion rate during a startup [9]. A modelling approach is proposed to evaluate the impact of the startup scenarios as well as the bipolar plate design on the carbon support corrosion. No simulation studies were performed so far on the design of the bipolar plate as a way to mitigate the carbon corrosion during startup/shutdown
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