Gas Diffusion Media and Their Degradation
Research output: Chapter in Book/Report/Conference proceeding › Chapter
Colleges, School and Institutes
- University of Birmingham
Gas diffusion media (GDM), also called gas diffusion layers (GDLs), are important sub-components in PEMFC membrane electrode assemblies (MEAs). The GDL, with its porous nature, plays an essential role in assisting the hydrogen oxidation (HOR) and oxygen reduction (ORR) reactions in the catalyst layers by allowing the reactants to diffuse from the flow field channels to the active sites on the electrocatalyst. It also facilitates water management in the catalyst layer and the polymeric proton exchange membrane (PEM), by allowing water vapor together with the reactants to diffuse out to ensure sufficient humidification for the PEM. At the same time, the GDLs are electrically connected to the catalyst ink and offer a supporting structure for the catalyst layers. In addition, it is an electrically conducting medium that transfers electrons between the catalyst layer and the flow field or bipolar plates (BPPs). However, GDL also suffers from electrochemical, mechanical and thermal degradation under PEM fuel cell operating conditions. This degradation results in changes in its properties, which affect the overall performance of loss of water transfer ability and changes in structure that affect the flows of reactants to the catalyst layer. PEM fuel cell degradation studies have mainly focused on studying membrane and catalyst layer degradation and little attention is given to GDL degradation. Further studies are required to develop a better understanding of these mechanisms, and methods for in-situ GDL degradation detection. Finally, GDL characteristics and durability tests need to be standardized.
|Title of host publication||Polymer Electrolyte Fuel Cell Degradation|
|Publication status||Published - 2011|