The Gas Diffusion Layer (GDL) is a very important supporting material in a Membrane Electrode Assembly (MEA). Gas diffusion layers are a porous material composed of a dense array of carbon fibers, which also provides an electrically conductive pathway for current collection. GDL plays an important role of electronic connection between the bipolar plate with channel-land structure and the electrode. In addition, the GDL also performs the following essential functions: passage for reactant transport and heat/water removal, mechanical support to the membrane electrode assembly (MEA), and protection of the catalyst layer from corrosion or erosion caused by flows or other factors. Physical processes in GDLs, in addition to diffusive transport, include bypass flow induced by in-plane pressure difference between neighboring channels, through-plane flow induced by mass source/sink due to electrochemical reactions, heat transfer like the heat pipe effect, two-phase flow, and electron transport.
The two types of gas diffusion layers most commonly used are carbon paper and carbon cloth. Both are carbon fiber based porous materials: carbon paper is non-woven, while carbon cloth is woven fabric, thus no binder is needed.
Gas Diffusion Layer's Main Functions:
1. A gas diffused pathway from flow channels to the catalyst layer.
2. Help to remove by-produced water outside of the catalyst layer and prevent flooding.
3. Keep some water on surface for conductivity through the membrane.
4. Heat transfer during cell operation.
5. Provide enough mechanical strength to hold membrane electrode assembly from extension caused by water absorbance.
Check out our Tech Article: What is the Difference Between Carbon Paper and Carbon Cloth Based Gas Diffusion Layers (GDL)?
View or Download all of our Gas Diffusion Layer (GDL) property sheets here.
If you need help selecting the appropriate GDL, take a look at our Gas Diffusion Layer Comparison Chart. We have compiled a table of over 20 of the most common GDL types and their specifications (as supplied by the manufacturers) in an easy to read format that will save you hours of searching through individual property sheets.