Gas diffusion layer for proton exchange membrane fuel cell and preparation method thereof

Abstract

The present invention relates to a gas diffusion layer for a proton exchange membrane fuel cell and a preparation method thereof. After the carbon fiber base paper is obtained by drying and drying, carbonization and graphitization are carried out under the protection of nitrogen or inert gas to obtain a gas diffusion layer for proton exchange membrane fuel cell; the fibrous binder is a composite fiber or Blended fibers; the final gas diffusion layer for a proton exchange membrane fuel cell has a pore gradient, and the layer with the smallest pore size is an intrinsic microporous layer. The method of the invention reduces the steps of infiltrating the resin with the base paper, can realize the integrated molding of the carbon paper and the microporous layer, reduces the coating and preparation of the subsequent microporous layer, has a simple process and reduces costs.

Description

technical field [0001] The invention belongs to the technical field of fuel cells, and relates to a gas diffusion layer for a proton exchange membrane fuel cell and a preparation method thereof. Background technique [0002] Fuel cell is a new and environmentally friendly power generation device, which can directly convert chemical energy stored in fuel into electrical energy. Since its power generation does not have severe combustion, and the conversion process is green and environmentally friendly, the use of fuel cells is a solution to the current energy crisis. effective way. Among various fuel cells, proton exchange membrane fuel cells are considered as one of the most potential power sources due to their high power density, high energy conversion efficiency, low temperature start-up, pollution-free, and lightweight. The fuel cell will generate a lot of water during operation. If there is no way to discharge it in time, the catalytic layer will be flooded, the entire c...

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Problems solved by technology

Adhesives can be solid, such as powder and fiber, or liquid, but powdery adhesives usually have problems with uneven distribution, resulting in poor material performance; liquid adhesives usually have uncontrollable adhesion and problems such as pollution

Chinese patent CN111900418A provides a method for preparing a carbon fiber paper prefabricated body for a gas diffusion layer of a fuel cell. Although adding a small amount of nanocellulose can significantly improve the dispersion of carbon fibers, the binder resin is immersed in the vacuum negative pressure suction process. Carbon paper still cannot solve the problems of uneven distribution of resin inside carbon paper and difficulty in controlling the amount of adhesion caused by its own fluidity and gravity, which will eventually lead to poor overall uniformity of carbon paper

Chinese patent CN101047253A provides a carbon fiber paper bonded with acrylic fibers. The acrylic fibers are introduced into the carbon fiber laminations through a conventional wet papermaking process, and then solidified and carbonized to prepare carbon fiber paper. The mixture is evenly distributed, but due to the low residual carbon rate of acrylic fibers, the bond strength between carbon fibers after carbonization is weak

Chinese patent CN112490454A prepares a gas diffusion layer with an integrated gradient structure composed of a carbon fiber layer and a microporous layer by means of transfer printing, which improves the bonding ability between the microporous layer and the carbon fiber substrate, and improves the conductivity and gas transmission capabilities, but its process More cumbersome and complicated, not conducive to large-scale production preparation

Chinese patent CN201811457447.6 uses sulfur atom-doped graphene and fluorinated ethylene-propylene copolymer to prepare the microporous layer, which shows good battery performance in medium and low humidity environments, and the maximum power density is higher than that of conventional microporous layers. 55%, but this preparation process is complex and uses extremely expensive graphene

The hydrophobicity / hydrophilicity of the diffusion layer used is relatively fixed, which cannot meet the complex working conditions of the fuel cell, which determines that the water management process of the current commercial fuel cell diffusion layer still needs to be optimized

Chinese patent CN111029605A uses carbon paper treated with a hydrophobic agent as a support layer, and uses a hydrophobic agent, a conductive agent and a dispersant as a microporous layer slurry, which is evenly sprayed on one side of the support layer, and then sprayed on the microporous layer with a hydrophilic agent in an atomized manner. On the pore layer, a gas diffusion layer with a hydrophilic and hydrophobic synergistic structure is made. However, when the current density is high, the generated water is easily accumulated in the hydrophilic area of ​​the microporous layer, resulting in water flooding.

Invention patent CN1378014A first prepares two kinds of carbon paper slurries with different compositions and hydrophobic properties, and then filters the pulp twice, presses and molds them, and then undergoes post-processing, so that the two sides after molding have different hydrophilic and hydrophobic properties, and the raw materials are cheap and easy to obtain , but the carbon paper formed by pressing the filter pulp twice will cause cracking in the middle, reducing its mechanical and conductive functions

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