Proton exchange membrane fuel cell (PEMFC) is a type of fuel cell generating electricity and operating on the opposite principle to PEM electrolysis, which consumes electricity. They are a leading candidate to replace the aging alkaline fuel-cell technology. Titanium sintered felt is placed in the gas diffusion layer and plays the role of air guide, drainage, electronic conductivity and support. The gas diffusion layer is mainly made of titanium sintered felt as raw materials, with a porosity of 60% to 80%. After hydrophobic treatment, hydrophilic channels and hydrophobic channels are formed. The hydrophilic channels can lead the water in the catalyst layer into the bipolar plate, while the hydrophobic channels provide transport paths for gas diffusion.

Air Guide & Drainage Function
Gas diffusion layer plays an important role in PEMFC membrane electrode and can effectively transport the hydrogen and oxygen in the bipolar plate to the catalytic layer to meet the reaction needs of catalytic layer; meanwhile, it can also drain out water generated in the catalytic layer to avoid water accumulating in the catalytic layer and hindering the progress of reaction. This phenomenon is called “water logging”. Therefore, the diffusion layer needs to be a porous material to ensure it has both good air permeability and good drainage performance.

Conductive & Support Function
The gas diffusion layer requires good electronic conductivity, so that the electrons generated from the catalytic layer can pass through the diffusion layer and reach the bipolar plate. In addition, the gas diffusion layer also provides a certain support strength for the membrane electrode. The gas diffusion layer is the thickness part of the membrane electrode, generally greater than 100 μm.