Degradation Study of the Cells Operated Under Low or High Humidity Conditions at Cathode and/or Anode

Monday, 27 July 2015: 17:00
Dochart (Scottish Exhibition and Conference Centre)
K. A. Friedrich (DLR), D. G. Sanchez, T. Ruiu, I. Biswas, S. Helmly (German Aerospace Center (DLR)), M. Schulze (Deutsches Zentrum für Luft- und Raumfahrt e.V.), and J. Sanchez-Monreal (Universidad Carlos III de Madrid)
Water management represents one of the main challenges for the design and operation of polymer electrolyte membrane fuel cells (PEMFC), the amount of water in the cell affects the performances and degradation processes. Commonly, the main goal is try to reduce the humidification in order to simplifying the humidification system and enhancing the performance stability of the cell. However, insufficient water content can lead to increased degradation and performance loss. These negative effects depend strongly on water distribution [1] in the cell and can therefore be highly non-uniform [2]. The relation between low humidification and degradation is complex and not yet fully understood. To bring more insight into this, the differences in the local conditions of the cell must be taken into account when examining performance and degradation. Thus, in this work, particular attention is paid to the local analysis of performance and degradation of cells operated under low or high humidity conditions at cathode and/or anode.

In order to study locally the degradation influence of inlet gas humidification on cell performance all the experiments were performaned with the DLR- PCB segmented cell current density measurements, other global effect were analyzed using in-situ diagnostic tools, such as cyclic voltammetry. The changes observed locally in the current densities distributions were investigated locally by post-mortem ex-situ investigations by XPS and SEM/EDX to determine changes in the chemical composition of the different layers during the experiment.

 [1] D. G. Sanchez and P. L. Garcia-Ybarra, Int. J. Hydrogen Energy, 37, 7279 (2012).

[2] D. G. Sanchez, D. G. Diaz, R. Hiesgen, I. Wehl and K. A. Friedrich, J. Electroanal. Chem., 649, 219 (2010).