Gas diffusion layer of PEMFC (Proton Exchange Membrane Fuel Cell) and preparation method thereof

Abstract

The invention discloses a gas diffusion layer of a PEMFC (Proton Exchange Membrane Fuel Cell). The gas diffusion layer comprises a substrate and a micropore layer, wherein the substrate is a porous metal net of which the surface is provided with an electroplating layer; the pore diameter of the porous metal net is 0.076-0.4mm, and the thickness of the porous metal net is 0.01-0.4mm; the micropore layer is formed by coating carbon black slurry on the surface of a carbon fiber fabric, and the substrate and the micropore layer are overlapped and then laminated into a whole. The preparation method comprises the following steps of: overlapping the sintered micropore layer and one or more layers of treated porous metal nets, and then pressing, thereby obtaining the gas diffusion layer which utilizes the metal net as the substrate. The preparation method is simple process and convenient to operate.

Description

technical field [0001] The invention belongs to a proton exchange membrane fuel cell, in particular to a gas diffusion layer of the proton exchange membrane fuel cell. Background technique [0002] The gas diffusion layer is one of the important core components of the proton exchange membrane fuel cell. It plays the role of water vapor transmission, supporting the catalytic layer and collecting current in the membrane electrode. Therefore, it plays a key role in the proton exchange membrane fuel cell. The composition of the gas diffusion layer includes a substrate and a microporous layer. At present, the base of the gas diffusion layer for fuel cells at home and abroad mostly uses carbon fiber to prepare carbon paper or carbon cloth. After the base is pretreated by hydrophobicity and leveling, a microporous layer is prepared on the surface. Spraying and other processes. The preparation process of the gas diffusion layer substrate prepared by this method is cumbersome and t...

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Problems solved by technology

Disadvantages: ①This technology adopts the method of carrying carbon powder on the metal mesh to treat the metal surface. Since the surface of the metal mesh is relatively smooth, the carbon powder has weak adhesion and is easy to fall off. Under the impact, the carbon powder is easier to peel off, and the peeled carbon powder is easy to block the pores of the microporous layer, affecting the water vapor transmission of the membrane electrode, and then affecting the performance of the membrane electrode

②The metal substrate of this technology needs to be treated with hydrophobicity. On the one hand, the hydrophobic treatment requires high-temperature sintering, and inert gas protection is required to prevent the oxidation of the metal substrate under high temperature conditions. The process is complex and time-consuming, which is not conducive to production; Hydrophobic treatment will reduce the conductivity of the metal mesh

③This technology adopts the method of direct spraying, dipping coating, scraping coating or screen printing on the surface of the metal mesh to prepare the microporous layer. First of all, this method has higher requirements on the pore diameter of the metal mesh, and the pore diameter should not be too large, otherwise the slurry will be easy to Leakage occurs; secondly, the metal mesh needs to be sintered together with the microporous layer, which may cause partial oxidation under the condition of an uncommon atmosphere; thirdly, the microporous layer is prepared directly on the metal mesh, which is troublesome to operate and is not conducive to production

Disadvantages: ① This technology uses carbon fiber material as the base, which is expensive, and the carbon fiber material is mainly carbon paper or carbon cloth, which is easily damaged during use and has high requirements for transportation

There are disadvantages: the metal matrix prepared by this method is complicated to operate, and the interlayer and graphite layer are prepared by ion plating on the metal fiber, and the price is relatively high

PTFE hydrophobically treats the surface of the metal, which affects the conductivity of the metal

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