A Spatially Resolved PEM Fuel Cell Catalyst Degradation Study Under Automotive Load Cycle for Durability Prediction

One of the limiting bottlenecks of polymer electrolyte membrane fuel cell (PEMFC) technology to create a breakthrough in cost-effectiveness and lifetime in automotive applications is the highly load-sensitive degradation of cell components. Most of the cell performance evaluation on the single cell or system level provides only an averaged insight into cell voltage and current values, and does not reveal the spatial behavior of the cell state variables. Since, the reported cell failure cases in the literature show highly localized cell component degradation, an averaged analysis will not be able to provide a thorough insight in the causes of the cell failure, nor to propose mitigation strategies. The spatial distribution of reactants concentration and pressure gradients in the flow field leads to a spatially varying cell operating behavior. This creates specific zones of variable performance in the membrane electrode assembly (MEA). Hence, one can observe the redistribution of the local current density, leading to uneven reactant utilization, reduced overall efficiency, and localized accelerated degradation [1,2].

In this study, with the help of a 2D multiphysics model [3] of a single cell, we can not only have a high spatio-temporal resolution of the fuel cell state variables, but also a detailed insight in the spatial degradation of cell component properties. In particular, we study the loss of electro-chemical active surface area (ECSA) based on an electrochemical degradation reaction mechanisms. The degradation is quantified spatially resolved along the flow length. Using an in-house system model of a car, we expose the fuel cell model to a highly transient loading cycle (New European Driving Cycle). Using a time-upscaling methodology, we present a predictive analysis of cell end-of-life under different operating conditions.

References:

1.    C. Robin, M. Gerard, A. A. Franco, and P. Schott, “Multi-scale coupling between two dynamical models for PEMFC aging prediction,” International Journal of Hydrogen Energy 38, 4675–4688 (2013).

2.    J. Dillet, D. Spernjak, A. Lamibrac, G. Maranzana, R. Mukundan, J. Fairweather, S. Didierjean, R. L. Borup, and O. Lottin, “Impact of flow rates and electrode specifications on degradations during repeated startups and shutdowns in polymer-electrolyte membrane fuel cells,” Journal of Power Sources 250, 68–79 (2014).

3.    C. Bao and W. G. Bessler, “Two-dimensional modeling of a polymer electrolyte membrane fuel cell with long flow channel. Part I. Model development,” Journal of Power Sources 275, 922–934 (2015).