Diffusion layer with gradient change of hydrophobicity as well as preparation method and application of diffusion layer

Abstract

The invention discloses a diffusion layer with gradient change of hydrophobicity as well as a preparation method and an application of the diffusion layer. The diffusion layer with gradient change of hydrophobicity comprises a porous base material and a microporous layer, wherein the porous base material is provided with a vertical hydrophobic layer, and micropores of the microporous layer are provided with a parallel hydrophobic layer with gradient change of hydrophobicity. The preparation method of the diffusion layer with gradient change of hydrophobicity comprises the steps as follows: pretreatment of the porous base material, hydrophobic treatment of the porous base material, preparation of slurry and preparation of the microporous layer. The diffusion layer with gradient change of hydrophobicity and a catalyst-loaded proton exchange membrane constitute a membrane electrode assembly to be applied to fuel cells. Compared with the prior art, the diffusion layer with gradient change of hydrophobicity has the advantages of being good in drainage effect, capable of preventing cells from being flooded and improving the performance of the fuel cells and the like. The preparation method has the advantages of being simple to operate, easy to industrialize, reasonable in design and the like.

Description

technical field [0001] The invention relates to the technical field of fuel cells, in particular to a diffusion layer with a gradient change in hydrophobicity and a preparation method and application thereof. Background technique [0002] A fuel cell is a device that converts chemical energy stored in fuel and oxidant into electrical energy. A proton exchange membrane fuel cell (PEMFC) is composed of a guide plate, a membrane electrode (a component coated with anode and cathode catalyst layers on both sides of the proton exchange membrane) and a diffusion layer. The reaction gas (the anode is usually hydrogen, the cathode is air or oxygen) is diverted through the guide plate, and then diffused to the surface of the catalyst through the gas diffusion layer to react. . In the reaction process of fuel cells, water management is an important process. It is necessary to ensure that the proton exchange membrane contains enough water to achieve the best conductivity, and it is al...

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Problems solved by technology

These patents have a certain hydrophobic gradient in the direction perpendicular to the catalytic layer (or diffusion layer) in a certain way, which is conducive to discharging the water generated by the reaction from the electrode surface into the flow guide channel, preventing the electrode surface from being flooded and hindering The reaction proceeds, but the above patents do not do a good job of controlling the water management in the direction parallel to the diffusion layer

As the water is discharged into the diversion tank, water will accumulate as the gas flows from the inlet to the outlet along the gas flow direction of the bipolar plate of the PEMFC, and the above patents do not do it in the direction parallel to the diffusion layer. Take good countermeasures to prevent the impact of water accumulation in the direction parallel to the diffusion layer

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