Performance Benefits of Multiwall Carbon Nanotubes in the Polymer Electrolyte Membrane Fuel Cell Gas Diffusion Layer

A commercial gas diffusion layer (GDL) with a microporous layer (MPL) containing multiwall carbon nanotubes (MWCNT) exhibited better performance in a polymer electrolyte membrane (PEM) fuel cell than that with a conventional GDL. This performance benefit was attributed to improved oxygen mass transport in the cathode GDL. The operation of the fuel cell was visualized with synchrotron X-ray radiography to measure the liquid water saturation in the two GDLs. A higher liquid water saturation was measured in the operating fuel with the MWCNT-based MPL than with the conventional MPL. But, the MWCNTs induced higher effective porosity within the GDL, allowing for improved overall oxygen transport, and thus the cell performed better even with higher saturation of liquid water in the GDL.