Humidity and Moisture in PEM Fuel Cells
In order for a fuel cell to function properly, the proton exchange membrane must retain moisture. If they are not fully humidified, the electrical conductivity decreases and therefore more energy is expended in the proton transport phenomenon. If it gets too dry, the membrane stops functioning as a proton transporter. Since hydrogen fuel cells consume hydrogen and oxygen to generate electricity and water, it seems like there should be plenty of water around. This creates the problem of potentially flooding the catalyst layer if the excess water is removed.
Hydrogen and oxygen (or air) need to reach catalyst sites and membranes to be converted into electricity. However, if there is any liquid water in the catalyst layer, it will cover the catalyst, and the gas cannot reach it, essentially rendering the underwater catalyst useless—significantly reducing the conversion of H2 and O2 into electricity.
This is why gas diffusion layers are key materials. GDL materials are specially formulated with hydrophobic coatings and permeabilities, all to help carry water away from the catalyst layer. This is further complicated when you consider that fuel cells operate in widely varying environments. Some need to work in hot/dry desert environments, while others need to work in very humid environments. Each manufacturer has a variety of GDL types optimized for different operating parameters and with different physical properties.
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Our coating solutions are environmentally-friendly, efficient and highly reliable, and enable dramatic reductions in overspray, savings in raw material, water and energy usage and provide improved process repeatability, transfer efficiency, high uniformity and reduced emissions.
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