Oscillations and Pattern Formation in a PEM Fuel Cell with Pt/Ru Anode Exposed to H-2/CO Mixtures

In this work, the behavior of a polymer electrolyte membrane (PEM) fuel cell with a Pt/Ru anode exposed to H-2/CO mixtures is investigated. A compact, isothermal one-dimensional model is derived to address the phenomena occurring at the along-the-channel direction. Besides material balances for the anode channel and electrode, the model considers charge balances for the membrane (Laplace equation) and both the anodic and cathodic double layers. The model predicts the formation of complex spatiotemporal patterns for a wide range of technical relevant operating conditions. The system can be understood as a chain of coupled oscillators. The electrical coupling is influenced by the electrolyte conductivity. Furthermore, the system features coupling by the anode gas channel dynamics. Depending on the ratio of the characteristic time for CO transport in the gas channel and the characteristic time required for CO adsorption, two limiting cases with varying degrees of complexity exist. The qualitative theoretical results of the present contribution give a guideline for the design of a validating experiment and pave the way for a systematic experimental analysis. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3469570] All rights reserved.