Design and selection of fuel cell gas diffusion layer

As an important component of the membrane electrode, the design and selection of the gas diffusion layer should be adapted to local conditions according to factors such as the water management characteristics of the stack, the size of the electrode plate, and the target thickness of the monomer.

The gas diffusion layer (GDL) is a type of hydrophobic porous medium material, located between the flow field plate and the catalytic layer, acting as a carrier for water and gas transport, heat transfer, and electron conduction, and provides structural support during assembly and operation. GDL is usually composed of a macroporous substrate (MPS) and a microporous layer (MPL). Among them, the base layer is usually composed of an anisotropic stack of carbon fibers and directly contacts the flow field plate; the microporous layer is formed by mixing carbon-based powder and a water-repellent agent and directly contacts the catalytic layer.

Key characteristics of gas diffusion layer

The gas diffusion layer is usually composed of a porous, non-woven, and macroporous carbon substrate. The substrate is hydrophobically treated with PTFE and coated with a single or multiple microporous layer (MPL). Generally, gas diffusion layer materials for proton exchange membrane fuel cells should have key characteristics such as reaction gas diffusion, product water diffusion and transport, electrical conductivity, heat conduction, and mechanical support.

Microporous layer

The microporous layer is a microporous structure composed of carbon powder and PTFE. The thickness and porosity of the microporous layer have an important impact on fuel cell performance. The thickness of the microporous layer directly affects the product water transmission rate, the electrical conductivity (contact resistance) of the gas diffusion layer and the mechanical strength (such as the surface roughness of the microporous layer). The following provides some basic comparative experiments to facilitate users to have a basic understanding of the design and selection of the microporous layer.

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