Modeling and investigation of design factors and their impact on carbon corrosion of PEMFC electrodes

Models of carbon corrosion induced by oxygen and hydrogen coexistence on the negative electrode are presented. In proton exchange membrane fuel cells (PEMFCs), this phenomenon occurs under several situations, such as start-up, shutdown, and hydrogen starvation. In the absence of hydrogen, the source of protons on the negative electrode is the oxygen reduction reaction. The solution potential decreases and induces an overpotential, eta(1)(s), large enough to cause carbon corrosion on the positive electrode even at low temperatures. The carbon corrosion current is large enough to influence the lifetime of PEMFCs not only in the case of high oxygen partial pressure, such as observed during start-up, but also in the case of low partial pressures such as a result of the permeation of oxygen through the membrane. The influence of key parameters for carbon corrosion is investigated. It is clear that the oxygen reduction activity on the negative electrode, the thickness of the membrane, and the cell potential can affect the carbon corrosion on the positive electrode significantly. (c) 2008 The Electrochemical Society.