CN203481322U - Gas diffusion layer of proton exchange membrane fuel cell - Google Patents

Abstract

The utility model discloses a gas diffusion layer of a proton exchange membrane fuel cell, which comprises a substrate and a microporous layer, wherein the substrate is a porous metal net, the surface of the porous metal net is provided with an electroplated layer, the aperture of the porous metal net is 0.076-0.4 mm, and the thickness of the porous metal net is 0.01-0.4 mm; the microporous layer is formed by coating carbon black slurry on the surface of a carbon fiber fabric, and the substrate and the microporous layer are overlapped and then are integrated through pressing. Has the advantages of simple process and convenient operation.

Description

Gas Diffusion Layers in Proton Exchange Membrane Fuel Cells

technical field

The utility model belongs to a proton exchange membrane fuel cell, in particular to a gas diffusion layer of a proton exchange membrane fuel cell.

Background technique

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 the price is high. The import price is about 300 US dollars per square meter, and most of the carbon paper market is occupied by Toray Company of Japan, SGL Company of Germany, and Ballard Company of Canada, which seriously affects the domestic diffusion. layer development.

In the prior art, Patent Publication No. CN101140990A, titled Application of an Electrode Gas Diffusion Layer in a Proton Exchange Membrane Fuel Cell, uses a metal mesh to carry carbon powder and a hydrophobic organic compound as an electrode gas diffusion layer. The preparation method is to level the surface of one side or both sides of the metal mesh with carbon powder and hydrophobic organic compound, and to obtain the electrode gas diffusion layer through high temperature treatment at 290-380°C under the protection of inert gas. The preparation method of the microporous layer is to directly prepare the microporous layer on the surface of the substrate by means of spray coating, dip coating, doctor blade coating or screen printing, and bake together. 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 more likely to peel off, and the peeled carbon powder is easy to block the pores of the microporous layer, affecting the water and gas 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; On the other hand, 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 . Patent Publication No. CN1323455C, the name is a method for making conductive and gas diffusion layer materials in electrochemical power generation devices. The process steps are: (1) select an organic film as a binder, and place a layer of metal or non-metal wire under the film net heating; (2) uniformly scatter polyacrylonitrile-based carbon fibers on the semi-molten organic film in step (1) and heat press to form a structural material-diffusion layer; (3) mix conductive powder with required Mix other materials into conductive powder paste, and transfer the conductive powder paste evenly to the object of step (2) by printing method --- drying on one or both sides of the diffusion layer; (4) the object of step (3) One or more sheets are hot pressed and pressed to make conductive and gas diffusion layer materials. The base material of the diffusion layer is carbon fiber material. There are deficiencies: 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. Patent Publication No. CN102082277 B. A metal gas diffusion layer for fuel cells and its preparation method, the main content of which is to prepare short stainless steel fiber sintered mats by vacuum high-temperature sintering, and then use closed-field unbalanced magnetron sputtering ions Plating technology prepares a chromium layer and a graphite layer on the pretreated stainless steel short fiber sintered felt at one time, then uses polytetrafluoroethylene to carry out hydrophobic treatment on the whole coated stainless steel short fiber sintered felt, and finally uses ultrasonic vibration method to clean the surface carbon powder. coating to obtain a metal gas diffusion layer for fuel cells. 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 acts as a hydrophobic treatment on metal surfaces, which affects the metal's electrical conductivity.

Utility model content

The utility model aims to overcome the defects of the prior art, and provides a gas diffusion layer for a proton exchange membrane fuel cell, which has the advantages of simple process and convenient operation.

In order to solve the above technical problems, the utility model provides the following technical solutions:

The gas diffusion layer of a proton exchange membrane fuel cell comprises a substrate and a microporous layer, the substrate is a porous metal mesh, the surface of the porous metal mesh is provided with an electroplating layer, and the porous metal mesh has an aperture of 0.076-0.4 mm. The thickness of the mesh is 0.01-0.4 mm; the microporous layer is coated on the surface of the carbon fiber fabric by carbon black slurry, and the substrate and the microporous layer are overlapped and bonded together by pressing.

The porous wire mesh is one of punched mesh, woven mesh, stretched mesh, laser perforated mesh, wire-cut mesh, powder metallurgy mesh, casting mesh, injection molding mesh, and foam mesh.

The material of the porous metal mesh is one of titanium, nickel, stainless steel, gold, silver mesh, laser perforated titanium plate, and nickel plate.

The surface of the electroplating layer is one of: carbon plating, titanium, titanium nitride, chromium nitride, chromium carbonitride, gold, black zinc, and black nickel.

A method for preparing a gas diffusion layer of a proton exchange membrane fuel cell, comprising the steps of:

(1) Surface treatment on the surface of the porous metal mesh;

(2) After preparing carbon black, dispersant and hydrophilic material into uniformly dispersed slurry, add hydrophobic agent, hydrophilic material, pore-forming agent and thickener to prepare the slurry into carbon black slurry with viscosity; Among them, the weight ratio of the added substances is carbon black 2-5: dispersant 0.6-3: hydrophobic agent 0.35-3.5: hydrophilic material 0.2-5: pore-forming agent 0.2-5: thickener 10-50;

The carbon black is one or more of Ketjen black, acetylene black, Cabot XC-72R, pearl black, conductive carbon black, graphite powder, graphene, carbon nanotubes, and expanded graphite;

The dispersant is one or more of polyethylene glycol isooctyl phenyl ether, polyoxyethylene sorbitan ether stearate, and fatty alcohol polyoxyethylene ether;

The hydrophobic agent is one or a mixed solution of polytetrafluoroethylene, polyvinylidene fluoride and polypropylene solution;

The hydrophilic material is a mixture of one or more of silica, alumina powder, and alumina fiber powder;

The pore-forming agent is one or more mixtures of ammonium chloride, ammonium bicarbonate, and ammonium oxalate;

The thickener is one or more mixtures of sodium hydroxymethyl cellulose and polyethylene glycol;

(3) Prepare the prepared carbon black slurry on the carbon fiber fabric by screen printing/blade coating, dry and sinter to obtain a microporous layer;

(4) After laminating the sintered microporous layer and one or more layers of treated porous wire mesh, pressing it to prepare a gas diffusion layer based on the wire mesh.

The thickness of the carbon fiber fabric in step (3) is 0.002-0.05 mm, the thickness of the microporous layer is 0.03-0.15 mm, and the sintering temperature is 200°C-400°C.

Compared with the prior art, the utility model has the following beneficial effects:

① Porous metal materials are used instead of carbon fiber materials as the substrate of the diffusion layer, which has a wide range of material sources, simple preparation process, low price, high mechanical strength, not easy to break, can effectively play a supporting role, and has excellent electrical conductivity.

②The porous metal material requires low pore diameter and uniformity, and prevents the slurry from penetrating into the substrate, and will not cause flooding due to condensed water in materials such as carbon paper/carbon cloth; the pore size range is conducive to water vapor transmission , without hydrophobic treatment, preventing the oxidation of porous metal caused by high-temperature sintering, and reducing the preparation process.

③ Hydrophobic agent is added to polytetrafluoroethylene to reduce the conductivity of the base material.

④ The microporous layer and the porous metal material are prepared separately, and the gas diffusion layer is prepared by pressing, which is conducive to large-scale production.

Description of drawings

Fig. 1 is the schematic diagram of the gas diffusion layer of the utility model proton exchange membrane fuel cell;

Fig. 2 is a scanning diagram of the membrane electrode polarization prepared by the metal mesh diffusion layer of the utility model.

Detailed ways

The preferred embodiments of the present utility model are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described here are only used to illustrate and explain the present utility model, and are not intended to limit the present utility model.

As shown in Figure 1, the gas diffusion layer of the proton exchange membrane fuel cell comprises a substrate 1 and a microporous layer 2, the substrate 1 is a porous metal mesh, and the surface of the porous metal mesh is provided with an electroplating layer 11, and the porous metal The diameter of the mesh is 0.05-0.4mm, and the thickness of the porous metal mesh is 0.01-0.4mm; the microporous layer 2 is coated on the surface of the carbon fiber fabric by carbon black slurry 21, and the substrate and the microporous layer are overlapped and bonded together by pressing. The porous wire mesh is one of punched mesh, woven mesh, stretched mesh, laser perforated mesh, wire-cut mesh, powder metallurgy mesh, casting mesh, injection molding mesh, and foam mesh.

The material of the porous metal mesh is one of titanium, nickel, stainless steel, gold, silver mesh, laser perforated titanium plate, and nickel plate.

The surface of the electroplating layer is one of: carbon plating, titanium, titanium nitride, chromium nitride, chromium carbonitride, gold, black zinc, and black nickel.

The preparation method one of the gas diffusion layer of the utility model proton exchange membrane fuel cell is as follows:

(1) A nickel mesh with a hole diameter of 0.15mm and a thickness of 0.2mm was used as the substrate. After cleaning the surface, a layer of carbon with a thickness of 0.003mm was coated on the surface by vacuum evaporation method to prepare the gas diffusion layer. base.

(2) ①Weigh 10g of acetylene black, and gradually disperse it in 40ml of 5% polyethylene glycol isooctyl phenyl ether by means of cell crushing; ②Weigh 7.14g of 60% PTFE solution, add 4g of water After dilution, add dropwise to ① the acetylene black slurry to prepare a slurry with a PTFE load of 30%; ③ Take 8g of silicon dioxide and 8g of ammonium chloride and dissolve them in ②; ④ Take 20g of PEG-600 drops Add it to the above ③, after the dropwise addition is complete, sonicate for 30 minutes to obtain a carbon black slurry.

(3) Prepare a microporous layer on a carbon fiber fabric with a thickness of 0.003 mm by scraping the prepared carbon black slurry. Sinter in a sintering furnace for 30 minutes.

(4) After superimposing the prepared microporous layer and a layer of porous metal material after surface treatment, press and press at 110°C and 0.5MPa for 2 minutes to obtain a gas diffusion layer based on porous metal.

(5) After combining the catalyst-coated membrane with a cathode and anode loading of 0.4 mg/cm ² and the gas diffusion layer of the metal substrate, the membrane electrode was prepared by pressing at 110 °C.

(6) Perform a single-cell polarization scan on a membrane electrode prepared with a wire mesh diffusion layer (as shown in Figure 2), where the test conditions are: battery temperature 45°C, H2 pressure 0.04MPa, air stoichiometric ratio 8.2, cathode and anode humidification The temperature is 20°C, no humidification, and the anode adopts the dead-end test method.

The second preparation method of the gas diffusion layer of the proton exchange membrane fuel cell is as follows:

(1) A nickel mesh with a hole diameter of 0.3mm and a thickness of 0.15mm is used as the substrate. After cleaning the surface, a layer of carbon with a thickness of about 0.003mm is plated on the surface by vacuum evaporation method to obtain the gas diffusion layer. base.

(2) ①Weigh 15g of acetylene black, and gradually disperse it in 90ml of 3% polyethylene glycol isooctyl phenyl ether by means of cell crushing; ②Weigh 6.24g of 60% PTFE solution, add 3g of water After dilution, add dropwise to ① the acetylene black slurry to prepare a slurry with a PTFE load of 20%; ③ Take 9g of silicon dioxide and 9g of ammonium chloride and dissolve them in ②; ④ Take 36g of PEG-600 drops Add it to the above ③, after the dropwise addition is complete, sonicate for 30 minutes to obtain a carbon black slurry.

(3) Prepare a microporous layer on a carbon fiber fabric with a thickness of 0.006 mm by scraping the prepared carbon black slurry. Sinter in a sintering furnace for 30 minutes.

(4) After superimposing the prepared microporous layer and a layer of porous metal material after surface treatment, they were pressed together at 110°C and 0.5 MPa for 2 minutes to obtain a gas diffusion layer based on porous metal.

(5) After combining the catalyst-coated membrane with a cathode and anode loading of 0.4 mg/cm ² and the gas diffusion layer of the metal substrate, the membrane electrode was prepared by pressing at 110 °C.

(6) Conduct single-cell polarization scanning on the membrane electrode prepared by the metal mesh diffusion layer. The test conditions are: battery temperature 45°C, H2 pressure 0.04MPa, air stoichiometric ratio 8.2, cathode and anode humidification temperature 20°C respectively , No humidification, the anode adopts the dead-end test method.

The above is only to illustrate the implementation of the utility model, and is not intended to limit the utility model. For those skilled in the art, any modification, equivalent replacement, Improvements and the like should all be included within the protection scope of the present utility model.

Claims (4)

1. the gas diffusion layers of Proton Exchange Membrane Fuel Cells, comprise substrate and microporous layers, it is characterized in that: described substrate is expanded metal, described porous metals net surface is provided with electrodeposited coating, described porous metals screen distance is 0.076-0.4 millimeter, and expanded metal thickness is 0.01-0.4 millimeter; Described microporous layers is coated on carbon fibre fabric surface by carbon black slurry, after substrate and microporous layers are overlapping, by pressing, is integrated.

2. the gas diffusion layers of Proton Exchange Membrane Fuel Cells as claimed in claim 1, is characterized in that: described porous metals silk screen is a kind of in punching net, mesh grid, stretching nets, laser drilling net, line cutting net, powder metallurgy net, casting net, injection moulding net, foam web.

3. the gas diffusion layers of Proton Exchange Membrane Fuel Cells as claimed in claim 1, is characterized in that: described expanded metal material is a kind of in titanium, nickel, stainless steel, gold, silver net, laser drilling titanium plate, nickel plate.

4. the gas diffusion layers of Proton Exchange Membrane Fuel Cells as claimed in claim 1, is characterized in that: described electrodeposited coating surface is: a kind of in plating carbon, titanium, titanium nitride, chromium nitride, carbon chromium nitride, gold, black zinc, black nickel.

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