A proton exchange membrane fuel cell cathode and a membrane electrode comprising the same

Abstract

The present invention belongs to the technical field of fuel cells, and specifically relates to a proton exchange membrane fuel cell cathode and a membrane electrode including the same. The cathode includes a cathode gas diffusion layer and a cathode catalyst layer arranged in sequence from the outside to the internal proton exchange membrane direction, and the cathode also includes a sulfur dioxide mass transfer barrier layer located outside the cathode gas diffusion layer; the sulfur dioxide mass transfer barrier layer includes a sulfur dioxide electro-oxidation catalyst and an alkaline resin binder, and the mass ratio of the sulfur dioxide electro-oxidation catalyst to the resin binder is 1:1-4:1. The present invention realizes the online removal of sulfur dioxide in the barrier layer by alkaline resin adsorption-electrocatalyst oxidation, inhibits the mass transfer of sulfur dioxide to the cathode catalyst layer, so as to reduce the poisoning effect of sulfur dioxide on the cathode catalyst, significantly improves the output performance of the fuel cell under the direct supply of sulfur dioxide-containing air, and thus improves the adaptability of the battery system to the operating environment.

Description

Technical Field

[0001] The invention belongs to the technical field of fuel cells, and in particular relates to a cathode of a proton exchange membrane fuel cell and a membrane electrode comprising the cathode. Background Art

[0002] Proton exchange membrane fuel cells can convert chemical energy in fuel into electrical energy. They are green and pollution-free, low noise, high energy conversion efficiency, and fast startup. They are widely considered to be the most promising energy conversion devices and have been widely used in transportation, household electricity, and distributed power stations. In actual use, compressed air is most commonly used as cathode feed gas in consideration of cost and convenience. However, because sulfur dioxide has a stronger ability to bind to platinum than oxygen, the platinum-based catalyst of the fuel cell is very sensitive to sulfur dioxide. Even trace amounts of sulfur dioxide in the air can cause irreversible performance degradation of the battery. In order to avoid the negative effects of sulfur dioxide, most fuel cell systems use purified air or pure oxygen as the cathode supply gas, which greatly increases the complexity and cost of the battery system.

[0003] At present, there are two main technical approaches to reduce the poisoning effect of sulfur dioxide: one is to optimize the catalyst, including alloying platinum-based catalysts, adding metal oxides to platinum-based catalysts, and developing non-precious metal catalysts. This approach is only in the laboratory stage, and no commercially recognized and effective anti-sulfur dioxide poisoning catalysts have been developed. The second is to pass the sulfur dioxide-containing air through an external purification device before it enters the cathode of the fuel cell, and desulfurize it by physical adsorption, chemical adsorption or electrochemical oxidation. However, the introduction of the new structure will increase the volume and weight of the battery system, which will not only increase the complexity and cost of the fuel cell system, but also increase the difficulty of integration with other electronic devices. Summary of the invention

[0004] The object of the present invention is to provide a proton exchange membrane fuel cell cathode and a membrane electrode including the same, which does not require an external purification device, realizes the online removal of sulfur dioxide in the barrier layer by the alkaline resin adsorption-catalyst oxidation in the sulfur dioxide mass transfer barrier layer, inhibits the mass transfer of sulfur dioxide to the cathode catalyst layer, significantly improves the output performance under the supply of sulfur dioxide-containing cathode, and thus improves the adaptability of the fuel cell system to the operating environment.

[0005] In order to achieve the above object, the technical solution of the present invention is as follows:

[0006] In one aspect, the present invention provides a cathode of a proton exchange membrane fuel cell, the cathode comprising a cathode gas diffusion layer and a cathode catalyst layer arranged in sequence from the outside to the inner proton exchange membrane direction, and the cathode further comprising a sulfur dioxide mass transfer barrier layer located outside the cathode gas diffusion layer;

[0007] The sulfur dioxide mass transfer barrier layer comprises a sulfur dioxide electro-oxidation catalyst and an alkaline resin binder, and the mass ratio of the sulfur dioxide electro-oxidation catalyst to the resin binder is 1:1-4:1.

[0008] Furthermore, the cathode gas diffusion layer comprises a cathode carbon paper and a cathode microporous layer which are sequentially arranged from the outside to the inside in the direction of the proton exchange membrane.

[0009] Furthermore, the sulfur dioxide mass transfer barrier layer is located outside the cathode carbon paper; the sulfur dioxide mass transfer barrier layer is coated on the outer surface of the cathode support layer, and the coating includes spraying, scraping, brushing or screen printing.

[0010] Furthermore, the sulfur dioxide electro-oxidation catalyst includes a combination of one or more carbon-supported metal materials, carbon materials, and doped carbon materials; the doped carbon materials include a combination of one or more nitrogen-doped carbon materials, oxygen-doped carbon materials, nitrogen-oxygen co-doped carbon materials, metal-doped carbon materials, and metal-nitrogen co-doped carbon materials; the carbon-supported metal material includes Pt / C or Au / C, and the carbon material includes carbon nanotubes, carbon fibers or carbon powder.

[0011] Furthermore, the alkaline resin binder includes one or more combinations of TP-85, TP-100, Fumion FAA, Sustainion®, and piperION®.

[0012] Furthermore, the loading amount of the sulfur dioxide electro-oxidation catalyst in the sulfur dioxide mass transfer barrier layer is 0.1-0.5 mg cm -2 .

[0013] Another aspect of the present invention provides a proton exchange membrane fuel cell membrane electrode, comprising a cathode, a proton exchange membrane and an anode stacked in sequence, wherein the cathode is the cathode described above.

[0014] Furthermore, the anode includes an anode gas diffusion layer and an anode catalyst layer which are arranged in sequence from the outside to the inside of the proton exchange membrane.

[0015] Furthermore, the anode gas diffusion layer includes an anode carbon paper and an anode microporous layer which are sequentially arranged from the outside to the inside of the proton exchange membrane.

[0016] The present invention also provides a fuel cell, comprising the above membrane electrode.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] (1) The cathode and membrane electrode comprising the cathode provided by the present invention use a conductive sulfur dioxide electrocatalyst and an alkaline resin binder to construct a sulfur dioxide mass transfer barrier layer integrated with the cathode gas diffusion layer without adding any additional structure to the fuel cell and almost without increasing the volume and mass of the battery, thereby fully ensuring the simplicity and portability of the battery structure.

[0019] (2) The alkaline resin component selected in the present invention not only acts as a binder but also serves as a site for adsorbing acidic sulfur dioxide gas, thereby inhibiting the mass transfer of sulfur dioxide to the catalyst layer. At the same time, the conductive sulfur dioxide electro-oxidation catalyst can further oxidize the trapped sulfur dioxide, releasing the sites for adsorbing sulfur dioxide inside the resin, and repeating a new round of capture-oxidation in the barrier layer. Therefore, the synergistic combination of the alkaline resin and the electro-oxidation catalyst achieves continuous and effective online oxidation removal of sulfur dioxide in the barrier layer.

[0020] (3) The membrane electrode of the present invention has an adaptable range for the working environment. The output power of the membrane electrode is improved under the supply of air containing sulfur dioxide. The fuel cell using the membrane electrode structure of the present invention is insensitive to the cathode supply gas, and the direct supply of air containing sulfur dioxide does not cause a significant change in the battery output performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the structure of the membrane electrode of the present invention;

[0022] In the figure, 1, cathode, 2, proton exchange membrane, 3, anode, 4, sulfur dioxide mass transfer barrier layer;

[0023] 101, cathode carbon paper, 102, cathode microporous layer, 103, cathode catalyst layer, 301, anode carbon paper, 302, anode microporous layer, 303, anode catalyst layer;

[0024] Figure 2 Performance comparison of PEMFC assembled with membrane electrodes of Examples 1, 3, 4 and the membrane electrode of Comparative Example 1 under different cathode supplies, a is Comparative Example 1, b is Example 1, c is Example 3, and d is Example 4. DETAILED DESCRIPTION

[0025] The technical solution of the present invention will be clearly and completely described below in conjunction with the drawings and embodiments. Obviously, the described embodiments are only part of the embodiments of the invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0026] Unless otherwise specified, the materials used in the embodiments of the present invention can be obtained through commercial channels or prepared according to conventional methods well known to those skilled in the art.

[0027] The present invention provides a proton exchange membrane fuel cell membrane electrode, the structure of which is as follows Figure 1 As shown, it includes an anode 3, a proton exchange membrane 2, and a cathode 1 stacked in sequence; the cathode 1 includes a cathode gas diffusion layer and a cathode catalyst layer 103 arranged in sequence from the outside to the inside of the proton exchange membrane 2, and the cathode 2 also includes a sulfur dioxide mass transfer barrier layer 4 located outside the cathode gas diffusion layer; the anode 3 includes an anode gas diffusion layer and an anode catalyst layer 303 arranged in sequence from the outside to the inside of the proton exchange membrane.

[0028] In one embodiment of the present invention, the cathode 1 includes a cathode carbon paper 101, a cathode microporous layer 102 and a cathode catalyst layer 103 arranged in sequence from the outside to the inside of the proton exchange membrane 2, and the sulfur dioxide mass transfer barrier layer 4 is located on the outside of the cathode carbon paper 101; the anode 3 includes an anode carbon paper 301, an anode microporous layer 302 and an anode catalyst layer 303 arranged in sequence from the outside to the inside of the proton exchange membrane.

[0029] Example 1

[0030] A proton exchange membrane fuel cell membrane electrode, such as Figure 1 As shown, nickel-nitrogen co-doped carbon (Ni-NC) is used to construct a sulfur dioxide mass transfer barrier layer, and the preparation method of the membrane electrode includes the following steps:

[0031] 5 mg Ni-NC was dissolved in 5 ml of anhydrous ethanol solution, and then 25 mg of 5 wt.% TP-100 solution was added as a binder and interception site for the sulfur dioxide mass transfer barrier layer to obtain the barrier layer ink. The cathode gas diffusion layer was composed of 5 wt.% PTFE hydrophobically treated carbon paper (Toray TGP-H-060) and PTFE content of 40 wt.%, carbon powder Vulcan XC-72 with a loading of 1 mg cm -2 The barrier layer ink is sprayed on one side of the outer surface of the carbon paper with an area of ​​5 cm*5 cm. The Ni-NC loading in the sulfur dioxide mass transfer barrier layer 4 is 0.1 mg cm -2 The mass fraction of TP-100 in the barrier layer ink solids is 20%; the anode gas diffusion layer is composed of 5wt.% PTFE hydrophobic treated Toray TGP-H-060 and PTFE content is 40wt.%, and the carbon powder Vulcan XC-72 loading is 1 mg cm -2The cathode gas diffusion layer and the catalyst-coated Nafion 211 membrane (the anode and cathode catalysts are Pt / C catalysts with a loading of 0.2 mg cm -2 and 0.4 mgcm -2 ), anode gas diffusion layer, and then stacked in sequence and hot pressed at 140°C and 0.1 MPa for 2 minutes to form a membrane electrode.

[0032] Example 2

[0033] Nickel-nitrogen co-doped carbon (Ni-NC) was used to construct a sulfur dioxide mass transfer barrier layer, and the membrane electrode was prepared by the same method as in Example 1, except that the alkaline resin binder used was 100 mg of 5 wt.% TP-100 solution, and the mass ratio of the sulfur dioxide electro-oxidation catalyst to the resin binder was 1:1.

[0034] Example 3

[0035] Nickel-nitrogen co-doped carbon (Ni-NC) was used to construct the sulfur dioxide mass transfer barrier layer. The membrane electrode was prepared by the same method as in Example 1, except that 12.5 mg of Ni-NC and 125 mg of 5 wt.% TP-100 solution were used, and the loading amount of Ni-NC in the sulfur dioxide mass transfer barrier layer 4 was 0.25 mg cm -2 , the mass ratio of the electro-oxidation catalyst to the resin binder is 2:1.

[0036] Example 4

[0037] The carbon powder Vulcan XC-72 is used to construct a sulfur dioxide mass transfer barrier layer. The preparation method of the membrane electrode includes the following steps:

[0038] 25 mg Vulcan XC-72 was dissolved in 5 ml of anhydrous ethanol solution, and then 500 mg 5 wt.% TP-100 solution was added as a binder and interception site for the sulfur dioxide mass transfer barrier layer to obtain the barrier layer ink. The cathode gas diffusion layer was composed of 5 wt.% PTFE hydrophobically treated carbon paper (Toray TGP-H-060) and PTFE content of 40 wt.%, carbon powder VulcanXC-72 loading of 1 mg cm -2 The barrier layer ink is sprayed on one side of the outer surface of the carbon paper with an area of ​​5 cm*5 cm. The loading amount of Vulcan XC-72 in the sulfur dioxide mass transfer barrier layer 4 is 0.5 mg cm -2The mass fraction of TP-100 in the barrier layer ink solids is 50%; the anode gas diffusion layer is composed of 5 wt.% PTFE hydrophobic treated Toray TGP-H-060 and PTFE content is 40wt.%, and the carbon powder Vulcan XC-72 loading is 1 mg cm -2 The cathode gas diffusion layer and the catalyst-coated Nafion 211 membrane (the anode and cathode catalysts are Pt / C catalysts, with a loading of 0.2 mg / cm -2 and 0.4 mg cm -2 ), anode gas diffusion layer, and then stacked in sequence and hot pressed at 140°C and 0.1 MPa for 2 minutes to form a membrane electrode.

[0039] Example 5

[0040] Carbon-supported platinum (Pt / C) is used to construct a sulfur dioxide mass transfer barrier layer. The preparation method of the membrane electrode includes the following steps:

[0041] 5 mg Pt / C was dissolved in 5 ml of anhydrous ethanol solution, and then 100 mg 5 wt.% TP-100 was added as a binder and interception site for the sulfur dioxide mass transfer barrier layer to obtain the barrier layer ink. The cathode gas diffusion layer was composed of 5 wt.% PTFE hydrophobically treated carbon paper (Toray TGP-H-060) and PTFE content of 40 wt.%, carbon powder Vulcan XC-72 with a loading of 1 mg cm -2 The barrier layer ink is sprayed on one side of the outer surface of the carbon paper with an area of ​​5 cm*5 cm. The Pt / C loading in the sulfur dioxide mass transfer barrier layer 4 is 0.1 mg cm -2 The mass fraction of TP-100 in the barrier layer ink solids is 50%; the anode gas diffusion layer is composed of 5wt.% PTFE hydrophobic treated Toray TGP-H-060 and PTFE content is 40wt.%, and the carbon powder Vulcan XC-72 loading is 1 mg cm -2 The cathode gas diffusion layer and the catalyst-coated Nafion 211 membrane (the anode and cathode catalysts are Pt / C catalysts with a loading of 0.2 mg cm -2 and 0.4 mgcm -2 ), anode gas diffusion layer, and then stacked in sequence and hot pressed at 140°C and 0.1 MPa for 2 minutes to form a membrane electrode.

[0042] Example 6

[0043] Carbon-supported platinum (Pt / C) was used to construct the sulfur dioxide mass transfer barrier layer, and the membrane electrode was prepared using the same method as in Example 5, except that the alkaline resin used was TP-85.

[0044] Example 7

[0045] Carbon-supported platinum (Pt / C) was used to construct the sulfur dioxide mass transfer barrier layer, and the membrane electrode was prepared using the same method as in Example 5, except that the alkaline resin binder used was Fumion FAA.

[0046] Example 8

[0047] Carbon-supported platinum (Pt / C) was used to construct the sulfur dioxide mass transfer barrier layer, and the membrane electrode was prepared using the same method as in Example 5, except that the alkaline resin binder used was Sustainion®.

[0048] Example 9

[0049] Carbon-supported platinum (Pt / C) was used to construct the sulfur dioxide mass transfer barrier layer, and the membrane electrode was prepared using the same method as in Example 5, except that the alkaline resin binder used was piperION®.

[0050] Comparative Example 1

[0051] A proton exchange membrane fuel cell membrane electrode comprises an anode, a proton exchange membrane, and a cathode stacked in sequence; the cathode comprises cathode carbon paper, a cathode microporous layer, and a cathode catalyst layer arranged in sequence from the outside to the inside of the proton exchange membrane; the anode comprises anode carbon paper, an anode microporous layer, and an anode catalyst layer arranged in sequence from the outside to the inside of the proton exchange membrane.

[0052] The cathode gas diffusion layer was composed of 5 wt.% PTFE hydrophobically treated carbon paper (Toray TGP-H-060) and 40 wt.% PTFE content and 1 mg cm-1 carbon powder Vulcan XC-72. -2 The anode gas diffusion layer is composed of 5 wt.% PTFE hydrophobic treated Toray TGP-H-060 and PTFE content of 40wt.%, carbon powder Vulcan XC-72 loading of 1 mgcm -2 The cathode gas diffusion layer and the catalyst-coated Nafion 211 membrane (the anode and cathode catalysts are Pt / C catalysts with a loading of 0.2 mg cm -2 and 0.4 mg cm -2 ), the anode gas diffusion layers are stacked in sequence and hot pressed at 140°C and 0.1MPa for 2 minutes to form a membrane electrode.

[0053] Test Example 1

[0054] The membrane electrode of Examples 1, 3, 4 and Comparative Example 1 was assembled into a fuel cell for performance evaluation. The test conditions were: battery operating temperature 80°C, back pressure 0.1 MPa, anode and cathode gas flow rates of 0.2 L / min and 0.8 L / min respectively, anode humidification 100%, cathode humidification 30% RH.

[0055] like Figure 2 As shown, the conventional membrane electrode structure battery in Comparative Example 1 ( Figure 2 a) After the introduction of sulfur dioxide-containing air, the performance was significantly reduced and could not withstand the poisoning effect of ppm-level sulfur dioxide. The performance of Example 1 and Example 3 was better than that of Example 4. Figure 2 b) and Example 3 ( Figure 2 c) The fuel cell with the membrane electrode structure is not sensitive to the cathode supply gas, and the direct supply of sulfur dioxide-containing air does not cause a significant change in the cell output performance, which proves that the membrane electrode structure of the present invention can improve the adaptability of the fuel cell system to the operating environment. Example 4 ( Figure 2 d) The performance of the membrane electrode fuel cell was slightly reduced after the air containing 10 ppm sulfur dioxide was introduced.

[0056] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A cathode of a proton exchange membrane fuel cell, the cathode comprising a cathode gas diffusion layer and a cathode catalyst layer arranged in sequence from the outside to the inside of the proton exchange membrane, characterized in that: The cathode further comprises a sulfur dioxide mass transfer barrier layer located outside the cathode gas diffusion layer; The sulfur dioxide mass transfer barrier layer comprises a sulfur dioxide electro-oxidation catalyst and an alkaline resin binder, wherein the mass ratio of the sulfur dioxide electro-oxidation catalyst to the resin binder is 1:1-4:1; The alkaline resin binder is TP-85 or TP-100.

2. The cathode according to claim 1, characterized in that: The cathode gas diffusion layer comprises cathode carbon paper and a cathode microporous layer which are arranged in sequence from the outside to the inner proton exchange membrane direction.

3. The cathode according to claim 2, characterized in that: The sulfur dioxide mass transfer barrier layer is located outside the cathode carbon paper.

4. The cathode according to claim 1, characterized in that: The sulfur dioxide electro-oxidation catalyst includes a combination of one or more of a carbon-supported metal material, a carbon material, and a doped carbon material.

5. The cathode according to claim 1, characterized in that: The loading amount of the sulfur dioxide electrooxidation catalyst in the sulfur dioxide mass transfer barrier layer is 0.1-0.5 mg cm -2 .

6. A proton exchange membrane fuel cell membrane electrode, comprising a cathode, a proton exchange membrane and an anode stacked in sequence, characterized in that: The cathode is the cathode according to any one of claims 1 to 5.

7. The membrane electrode according to claim 6, characterized in that: The anode comprises an anode gas diffusion layer and an anode catalyst layer which are arranged in sequence from the outside to the inner proton exchange membrane.

8. The membrane electrode according to claim 6, characterized in that: The anode gas diffusion layer comprises an anode carbon paper and an anode microporous layer which are sequentially arranged from the outside to the inner proton exchange membrane direction.

9. A fuel cell, characterized in that: A membrane electrode comprising any one of claims 6 to 8.

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