Membrane electrode and fuel cell

Abstract

The invention discloses a membrane electrode and a fuel cell, and belongs to the field of fuel cells, the membrane electrode for the fuel cell comprises a cathode diffusion layer, a cathode catalyst layer, a proton exchange membrane, an anode catalyst layer and an anode diffusion layer which are stacked in sequence, and the membrane electrode is provided with a first area and a second area which are arranged in sequence in the hydrogen flowing direction, the contact angle of the cathode catalyst layer in the second area is larger than that in the first area; the contact angle of the cathode catalyst layer in the second area is larger than the contact angle of the cathode diffusion layer, and the contact angle of the cathode catalyst layer in the first area is smaller than the contact angle of the cathode diffusion layer. Through the arrangement, the drainage of the cathode catalyst layer in the second region can be improved, the diffusion of cathode water in the second region to the anode catalyst layer is reduced, the anode catalyst layer in the second region is prevented from being flooded, and meanwhile, the water-retaining property of the cathode catalyst layer in the first region is improved; and the water distribution uniformity of the whole cathode catalyst layer and the anode catalyst layer is realized.

Description

Technical Field

[0001] The present application relates to the field of fuel cells, and in particular to a membrane electrode and a fuel cell. Background Art

[0002] Polymer electrolyte membrane fuel cells (PEMFCs) are usually composed of a proton exchange membrane sandwiched between two catalyst layers, two porous gas diffusion layers, and two bipolar plates with flow channels. Protons and electrons produced by the hydrogen oxidation reaction in the anode catalyst layer flow through the proton exchange membrane and the external circuit respectively, and participate in the oxygen reduction reaction in the cathode catalyst layer, producing water and waste heat.

[0003] Although considerable progress has been made in overall cell performance, the key performance and durability limitations focus on water management of PEMFCs, namely the transport of product water (liquid and vapor) and the resulting drying and / or flooding of component parts. Too little water can cause membrane electrode drying, which increases ionic resistance and exacerbates voltage drop due to ohmic losses. Too much water can cause flooding and block the pores of the catalyst layer and gas diffusion layer, thereby reducing the transfer rate of reactant gases to the catalyst sites. Inappropriate humidity conditions can not only reduce the performance and efficiency of the fuel cell, but can even lead to irreversible degradation of internal components such as catalysts or membranes. For example, under drier conditions, the proton exchange membrane is more susceptible to free radical attack, resulting in chemical corrosion and damage. Under wetter conditions, Pt catalysts are prone to mobility loss and Pt banding problems. At the same time, over-humidification can easily lead to local anode undergassing and reverse polarity problems, which seriously affect the long-term durability of the stack. Therefore, water management is a key issue in proton exchange membrane fuel cells. Summary of the invention

[0004] The present application provides a membrane electrode and a fuel cell, which can alleviate the overall or local gas shortage problem and improve the sensitivity, life and safety of the fuel cell to different humidity.

[0005] The embodiment of the present application is implemented as follows:

[0006] In a first aspect, the present application provides an example of a membrane electrode for a fuel cell, the fuel cell having a hydrogen outlet and a hydrogen inlet, the membrane electrode comprising a cathode diffusion layer, a cathode catalyst layer, a proton exchange membrane, an anode catalyst layer and an anode diffusion layer stacked in sequence, the membrane electrode having a first region and a second region arranged in sequence along a hydrogen flow direction, the first region corresponding to the hydrogen inlet, and the second region corresponding to the hydrogen outlet;

[0007] The contact angle of the cathode catalyst layer in the second region is greater than the contact angle in the first region;

[0008] The contact angle of the cathode catalyst layer in the second region is greater than the contact angle of the cathode diffusion layer, and the contact angle of the cathode catalyst layer in the first region is less than the contact angle of the cathode diffusion layer.

[0009] The membrane electrode provided by the present application facilitates the transfer of water from the second area of ​​the cathode catalyst to the first area by making the contact angle of the cathode catalyst layer in the second area greater than the contact angle of the cathode diffusion layer. At this time, the contact angle of the cathode catalyst layer in the second area is controlled to be greater than the contact angle of the cathode diffusion layer, which can improve the drainage of the cathode catalyst layer in the second area, reduce the diffusion of cathode water in the second area to the anode catalyst layer, and avoid flooding of the anode catalyst layer in the second area. At the same time, controlling the contact angle of the cathode catalyst layer in the first area to be less than the contact angle of the cathode diffusion layer can increase the water retention of the cathode catalyst layer in the first area, thereby achieving a comprehensive effect to achieve uniformity of water distribution in the entire cathode catalyst layer and the anode catalyst layer, improve the sensitivity of the fuel cell to different humidity levels, alleviate the overall or local gas shortage problem caused by flooding, and improve the life and safety of the fuel cell.

[0010] In some optional embodiments, taking the area of ​​the cathode catalyst layer as the catalytically active area of ​​the membrane electrode, the first region accounts for 40%-60% of the catalytically active area, and the second region accounts for 40%-60% of the catalytically active area.

[0011] In some optional embodiments, the contact angle of the anode catalyst layer in the second region is greater than the contact angle of the anode diffusion layer, and the contact angle of the anode catalyst layer in the first region is less than the contact angle of the anode diffusion layer.

[0012] In some optional embodiments, the difference between the contact angle of the cathode catalyst layer in the second region and the contact angle of the cathode diffusion layer is 5°-10°.

[0013] In some optional embodiments, the difference between the contact angle of the cathode catalyst layer in the first region and the contact angle of the cathode diffusion layer is 5°-10°.

[0014] In some optional embodiments, the contact angle of the cathode catalyst layer in the second region is smaller than the contact angle of the anode catalyst layer in the second region.

[0015] In some optional embodiments, the contact angle of the cathode catalyst layer in the first region is greater than the contact angle of the anode catalyst layer in the first region.

[0016] In some optional embodiments, the contact angle of the cathode catalyst layer in the second region is 140°-150°, and the contact angle of the cathode catalyst layer in the first region is 120°-130°.

[0017] In some optional embodiments, the contact angle of the anode catalyst layer in the second region is 140°-150°, and the contact angle of the anode catalyst layer in the first region is 120°-130°.

[0018] In some optional embodiments, the contact angles of the cathode diffusion layer and / or the anode diffusion layer are 130°-140° respectively;

[0019] Optionally, the cathode diffusion layer and the anode diffusion layer are carbon paper layers respectively.

[0020] In a second aspect, the present application provides an example of a fuel cell, the fuel cell comprising at least one membrane electrode provided in the first aspect of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 A schematic diagram of the structure of the membrane electrode provided in Example 1 of the present application;

[0023] Figure 2 This is a scanning electron microscope image of the cathode catalyst layer at the hydrogen outlet position and the proton exchange membrane near the cathode after long-term operation of the membrane electrode provided in Example 1 of the present application;

[0024] Figure 3 This is a scanning electron microscope image of the cathode catalyst layer at the hydrogen outlet position and the proton exchange membrane close to the cathode after long-term operation of the membrane electrode provided in Comparative Example 1 of the present application.

[0025] Icon: 10-membrane electrode; 11-hydrogen inlet; 12-hydrogen outlet; 13-oxygen inlet; 14-oxygen outlet; 15-first area; 16-second area. DETAILED DESCRIPTION

[0026] The embodiments of the present application will be described in detail below in conjunction with the examples, but it will be appreciated by those skilled in the art that the following examples are only used to illustrate the present application and should not be considered as limiting the scope of the present application. In the examples, if specific conditions are not specified, they are carried out according to normal conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0027] Overall or local gas shortage has always been a difficult problem that challenges the design and component response of fuel cells under variable load conditions for vehicles, especially the problem of local gas shortage at the anode. Accompanied by the reverse current mechanism, local gas shortage at the anode can form a high potential at the cathode, which in turn causes corrosion of the carbon carrier. Under the common hydrogen-air countercurrent intake structure, anode water management has attracted much attention. As the electrochemical reaction proceeds, the hydrogen partial pressure from the inlet of the anode active area to the outlet of the active area gradually decreases, and the water vapor partial pressure increases. The risk of "flooding" in the outlet area is relatively high, and local gas shortage may occur at any time. Due to the low temperature at the cathode inlet, the membrane is prone to dryness, which causes the problem of excessive humidity difference between the inlet and outlet of the membrane electrode.

[0028] In view of this, this application is hereby filed.

[0029] The following is a detailed description of the membrane electrode and fuel cell of the embodiment of the present application:

[0030] In a first aspect, the present application provides a membrane electrode for a fuel cell, the fuel cell having a hydrogen outlet and a hydrogen inlet, the membrane electrode comprising a cathode diffusion layer, a cathode catalyst layer, a proton exchange membrane, an anode catalyst layer and an anode diffusion layer stacked in sequence, the membrane electrode having a first region and a second region arranged in sequence along a hydrogen flow direction, the first region corresponding to the hydrogen inlet, and the second region corresponding to the hydrogen outlet;

[0031] The contact angle of the cathode catalyst layer in the second region is greater than the contact angle in the first region;

[0032] The contact angle of the cathode catalyst layer in the second region is greater than the contact angle of the cathode diffusion layer, and the contact angle of the cathode catalyst layer in the first region is less than the contact angle of the cathode diffusion layer.

[0033] The cathode catalyst layer contains a cathode catalyst, and the anode catalyst layer contains an anode catalyst.

[0034] The contact angle of the cathode catalyst layer refers to the contact angle of the surface of the catalyst layer facing the corresponding cathode diffusion layer. The contact angle of the cathode diffusion layer refers to the contact angle of the surface of the diffusion layer facing the cathode catalyst layer.

[0035] The contact angle test method of the cathode / anode catalyst layer is as follows: the cathode / anode catalyst layer is placed on a contact angle measuring instrument platform, and the contact angle test of the first area and the second area is performed.

[0036] The contact angle test method of the cathode / anode diffusion layer is as follows: the cathode / anode diffusion layer is placed on a contact angle measuring instrument platform to perform a contact angle test.

[0037] It can be understood that the larger the contact angle, the higher the hydrophobicity, and the easier it is for water to transfer from the side with high hydrophobicity to the side with low hydrophobicity. The contact angle of the cathode catalyst layer in the second region is greater than that in the first region, that is, the hydrophobicity of the cathode catalyst layer in the second region is greater than that in the first region, which is conducive to the transfer of water from the second region of the cathode catalyst to the first region, that is, it is conducive to the transfer of water from the side of the cathode catalyst corresponding to the hydrogen outlet to the side corresponding to the hydrogen inlet.

[0038] The membrane electrode provided by the present application facilitates the transfer of water from the second area of ​​the cathode catalyst to the first area by making the contact angle of the cathode catalyst layer in the second area greater than the contact angle of the cathode diffusion layer. At this time, the contact angle of the cathode catalyst layer in the second area is controlled to be greater than the contact angle of the cathode diffusion layer, which can improve the drainage of the cathode catalyst layer in the second area, reduce the diffusion of cathode water in the second area to the anode catalyst layer, and avoid flooding of the anode catalyst layer in the second area. At the same time, controlling the contact angle of the cathode catalyst layer in the first area to be less than the contact angle of the cathode diffusion layer can increase the water retention of the cathode catalyst layer in the first area, thereby achieving a comprehensive effect to achieve uniformity of water distribution in the entire cathode catalyst layer and the anode catalyst layer, improve the sensitivity of the fuel cell to different humidity levels, alleviate the overall or local gas shortage problem caused by flooding, and improve the life and safety of the fuel cell.

[0039] In some optional embodiments, taking the area of ​​the cathode catalyst layer as the catalytically active area of ​​the membrane electrode, the first region accounts for 40%-60% of the catalytically active area, and the second region accounts for 40%-60% of the catalytically active area.

[0040] That is, the first region accounts for 40%-60% of the catalytically active region of the entire membrane electrode (calculated by the cathode catalyst layer area). The second region accounts for 40%-60% of the catalytically active region of the entire membrane electrode (calculated by the cathode catalyst layer area).

[0041] Exemplarily, the area of ​​the first region or the second region accounts for any value among 40%, 45%, 50%, 55% and 60% of the catalytic active region area of ​​the entire membrane electrode (calculated based on the cathode catalyst layer area) or between any two values.

[0042] In some optional embodiments, the contact angle of the anode catalyst layer in the second region is greater than the contact angle of the anode diffusion layer, and the contact angle of the anode catalyst layer in the first region is less than the contact angle of the anode diffusion layer.

[0043] The contact angle of the anode catalyst layer refers to the contact angle of the surface of the catalyst layer facing the corresponding anode diffusion layer. The contact angle of the anode diffusion layer refers to the contact angle of the surface of the diffusion layer facing the anode catalyst layer.

[0044] By utilizing the fact that the contact angle of the anode catalyst layer in the second region is greater than the contact angle of the anode diffusion layer, diffusion of water in the anode catalyst layer in the second region to the anode diffusion layer is promoted, which is beneficial to improving the drainage of the anode catalyst layer in the second region and avoiding flooding of the anode catalyst layer in the second region; by utilizing the fact that the contact angle of the anode catalyst layer in the first region is less than the contact angle of the anode diffusion layer, it is beneficial to improving the water retention of the anode catalyst layer in the first region and to achieving uniform water distribution throughout the anode catalyst layer.

[0045] In some optional embodiments, the difference between the contact angle of the cathode catalyst layer in the second region and the contact angle of the cathode diffusion layer is 5°-10°.

[0046] It can be understood that the contact angle of the cathode catalyst layer in the second region is greater than the contact angle of the cathode diffusion layer, that is, the contact angle difference here refers to the contact angle of the cathode catalyst layer in the second region minus the contact angle of the cathode diffusion layer.

[0047] Controlling the difference in contact angles between the two within the above range is beneficial to improving drainage of the cathode catalyst layer in the second region, reducing diffusion of cathode water in the second region to the anode catalyst layer, and avoiding flooding of the anode catalyst layer in the second region.

[0048] Illustratively, the difference between the contact angle of the cathode catalyst layer in the second region and the contact angle of the cathode diffusion layer is any value of 5°, 6°, 7°, 8°, 9°, 10° or between any two values.

[0049] In some optional embodiments, the difference between the contact angle of the cathode catalyst layer in the first region and the contact angle of the cathode diffusion layer is 5°-10°.

[0050] It can be understood that the contact angle of the cathode catalyst layer in the first region is smaller than the contact angle of the cathode diffusion layer, that is, the contact angle difference here refers to the contact angle of the cathode diffusion layer minus the contact angle of the cathode catalyst layer in the second region.

[0051] Controlling the difference between the contact angles of the two within the above range is beneficial to increasing the water retention of the cathode catalyst layer in the first region.

[0052] Illustratively, the difference between the contact angle of the cathode catalyst layer in the first region and the contact angle of the cathode diffusion layer is any value of 5°, 6°, 7°, 8°, 9°, 10° or between any two values.

[0053] In some optional embodiments, the contact angle of the cathode catalyst layer in the second region is smaller than the contact angle of the anode catalyst layer in the second region.

[0054] The above arrangement is conducive to the transfer of water in the anode catalyst layer from the second area to the second area of ​​the cathode catalyst layer, and is conducive to the cooperation with the cathode catalyst layer and cathode diffusion layer to achieve uniform water distribution in the entire cathode catalyst layer and anode catalyst layer.

[0055] In some optional embodiments, the contact angle of the cathode catalyst layer in the first region is greater than the contact angle of the anode catalyst layer in the first region.

[0056] The above arrangement is conducive to achieving uniform water distribution throughout the cathode catalyst layer and the anode catalyst layer.

[0057] In some optional embodiments, the contact angle of the cathode catalyst layer in the second region is 140°-150°, and the contact angle of the cathode catalyst layer in the first region is 120°-130°.

[0058] Exemplarily, the contact angle of the cathode catalyst layer in the second region is any one of 140°, 142°, 145°, 147°, 150°, or between any two values.

[0059] Illustratively, the contact angle of the cathode catalyst layer in the first region is any one of 120°, 121°, 123°, 125°, 127°, 130°, or between any two values.

[0060] In some optional embodiments, the contact angle of the anode catalyst layer in the second region is 140°-150°, and the contact angle of the anode catalyst layer in the first region is 120°-130°.

[0061] Illustratively, the contact angle of the anode catalyst layer in the second region is any one of 140°, 142°, 145°, 147°, 150°, or between any two values.

[0062] Illustratively, the contact angle of the anode catalyst layer in the first region is any value of 120°, 121°, 123°, 125°, 127°, 130°, or between any two values.

[0063] In some optional embodiments, the contact angles of the cathode diffusion layer and / or the anode diffusion layer are respectively 130°-140°.

[0064] Exemplarily, the contact angles of the cathode diffusion layer and / or the anode diffusion layer are any value of 130°, 132°, 135°, 137°, 140°, or between any two values.

[0065] Controlling the contact angles of the cathode catalyst layer, anode catalyst layer, cathode diffusion layer and / or anode diffusion layer within the above ranges is beneficial to the comprehensive effect, achieving uniformity of water distribution in the entire cathode catalyst layer and anode catalyst layer, and improving the sensitivity, safety and life of the fuel cell to different humidity.

[0066] Optionally, the cathode diffusion layer and the anode diffusion layer are carbon paper layers respectively.

[0067] It should be noted that the first region and the second region of each of the above-mentioned cathode / anode catalyst layers can be hydrophilically treated and hydrophobically treated according to the actual contact angle requirements, wherein the hydrophilic treatment includes but is not limited to adding, for example, water-retaining components to the cathode / anode catalyst layers in the corresponding regions, or directly using hydrophilic catalysts, hydrophilic ion conductors, etc., wherein the water-retaining components include but are not limited to at least one of SiO2, TiO2 or polyvinyl alcohol; the hydrophobic treatment includes but is not limited to adding hydrophobic components, using hydrophobic catalysts, hydrophobic ion conductors, etc.

[0068] The cathode / anode diffusion layer can also be selected according to the actual contact angle or adjusted by hydrophilicity and hydrophobicity such as PTFE.

[0069] A second aspect of the present application provides a fuel cell, which includes at least one membrane electrode provided by the first aspect of the present application.

[0070] The membrane electrode and fuel cell of the present application are further described in detail below in conjunction with the embodiments.

[0071] Example 1

[0072] See also Figure 1 The fuel cell has a hydrogen outlet 11, a hydrogen inlet 12, an oxygen outlet 13, and an oxygen inlet 14, wherein the hydrogen outlet 11 and the hydrogen inlet 12 are arranged diagonally along the membrane electrode, and the oxygen outlet 13 and the oxygen inlet 14 are arranged diagonally along the membrane electrode.

[0073] The membrane electrode comprises a cathode diffusion layer, a cathode catalyst layer, a proton exchange membrane, an anode catalyst layer and an anode diffusion layer stacked in sequence along the thickness direction, and the membrane electrode has a first region 15 and a second region 16 arranged in sequence along the hydrogen flow direction, wherein the first region 15 corresponds to the hydrogen inlet 11, and the second region 16 corresponds to the hydrogen outlet 12. The first region 15 and the second region 16 are as follows Figure 1 The electrodes are shown arranged diagonally along the membrane.

[0074] 1. Catalyst coated membrane (CCM) preparation:

[0075] First region cathode catalyst layer: Weigh 1.5g 60wt% Pt / C cathode catalyst, 3g Nafion D2020 ionomer solution and 0.1g PVA hydrophilic component, add 20g water and 60g ethanol to mix and disperse to obtain the first region cathode catalyst layer slurry, spray the slurry on one side of the proton exchange membrane, and form the first region cathode catalyst layer after drying, so that the first region cathode catalyst layer occupies one half of the entire cathode catalyst layer area, and the contact angle of the first region cathode catalyst layer is tested to be 120°.

[0076] First region anode catalyst layer: Weigh 1.5g 60wt% Pt / C anode catalyst, 3g Nafion D2020 ionomer solution and 0.1g PVA hydrophilic component, add 20g water and 60g ethanol to mix and disperse to obtain the first region anode catalyst layer slurry, spray the slurry on the other side of the proton exchange membrane, and form the first region anode catalyst layer after drying, so that the first region anode catalyst layer occupies one half of the area of ​​the entire anode catalyst layer, and the contact angle of the first region anode catalyst layer is tested to be 120°.

[0077] Second region cathode catalyst layer: Weigh 1.5g 60wt% Pt / C cathode catalyst, 3g Nafion D2020 ionomer solution and 0.1g PTFE hydrophobic component, add 20g water and 60g ethanol to mix and disperse to obtain the second region cathode catalyst layer slurry, spray the slurry on one side of the proton exchange membrane, and form the second region cathode catalyst layer after drying, so that the second region cathode catalyst layer occupies one half of the area of ​​the entire cathode catalyst layer, and the contact angle of the second region cathode catalyst layer is tested to be 140°.

[0078] Second region anode catalyst layer: Weigh 1.5g 60wt% Pt / C anode catalyst, 3g Nafion D2020 ionomer solution and 0.1g PTFE hydrophobic component, add 20g water and 60g ethanol to mix and disperse to obtain the second region anode catalyst layer slurry, spray the slurry on the other side of the proton exchange membrane, and form the second region anode catalyst layer after drying, so that the second region anode catalyst layer occupies one half of the area of ​​the entire anode catalyst layer, and the contact angle of the second region anode catalyst layer is tested to be 140°.

[0079] 2. Preparation of membrane electrode (MEA):

[0080] Anode carbon paper and cathode carbon paper with contact angles of 130° were selected, and the anode carbon paper, CCM and cathode carbon paper were packaged with a frame to form an MEA.

[0081] Comparative Example 1

[0082] 1. Catalyst coated membrane (CCM) preparation:

[0083] Cathode catalyst layer: Weigh 1.5g of 60wt% Pt / C cathode catalyst and 3g of NafionD2020 ionomer solution, add 20g of water and 60g of ethanol to mix and disperse to obtain cathode catalyst layer slurry, spray the slurry on one side of the proton exchange membrane, and form a cathode catalyst layer after drying. The tested contact angle is 130°.

[0084] Anode catalyst layer: Weigh 1.5g of 60wt% Pt / C anode catalyst and 3g of NafionD2020 ionomer solution, add 20g of water and 60g of ethanol to mix and disperse to obtain anode catalyst layer slurry, spray the slurry on the other side of the proton exchange membrane, and form an anode catalyst layer after drying. The tested contact angle is 130°.

[0085] 2. Preparation of membrane electrode (MEA):

[0086] Anode carbon paper and cathode carbon paper with a contact angle of 130° were selected, and the anode carbon paper, CCM and cathode carbon paper were packaged with a frame to form an MEA.

[0087] Comparative Example 2

[0088] 1. Catalyst coated membrane (CCM) preparation:

[0089] Cathode catalyst layer: Weigh 1.5g of 60wt% Pt / C cathode catalyst, 3g of NafionD2020 ionomer solution and 0.1g of PVA hydrophilic component, add 20g of water and 60g of ethanol to mix and disperse to obtain cathode catalyst layer slurry, spray the slurry on one side of the proton exchange membrane, and form a cathode catalyst layer after drying. The tested contact angle is 120°.

[0090] Anode catalyst layer: Weigh 1.5g of 60wt% Pt / C anode catalyst, 3g of NafionD2020 ionomer solution and 0.1g of PVA hydrophilic component, add 20g of water and 60g of ethanol to mix and disperse to obtain anode catalyst layer slurry, spray the slurry on the other side of the proton exchange membrane, and form an anode catalyst layer after drying. The tested contact angle is 120°.

[0091] 2. Preparation of membrane electrode (MEA):

[0092] Anode carbon paper and cathode carbon paper with a contact angle of 130° were selected, and the anode carbon paper, CCM and cathode carbon paper were packaged with a frame to form an MEA.

[0093] Comparative Example 3

[0094] 1. Catalyst coated membrane (CCM) preparation:

[0095] Cathode catalyst layer: Weigh 1.5g of 60wt% Pt / C cathode catalyst, 3g of NafionD2020 ionomer solution and 0.1g of PTFE hydrophobic component, add 20g of water and 60g of ethanol to mix and disperse to obtain cathode catalyst layer slurry, spray the slurry on one side of the proton exchange membrane, and form a cathode catalyst layer after drying. The tested contact angle is 140°.

[0096] Anode catalyst layer: Weigh 1.5g of 60wt% Pt / C anode catalyst, 3g of NafionD2020 ionomer solution and 0.1g of PTFE hydrophobic component, add 20g of water and 60g of ethanol to mix and disperse to obtain anode catalyst layer slurry, spray the slurry on the other side of the proton exchange membrane, and form an anode catalyst layer after drying. The tested contact angle is 140°.

[0097] 2. Preparation of membrane electrode (MEA):

[0098] Anode carbon paper and cathode carbon paper with a contact angle of 130° were selected, and the anode carbon paper, CCM and cathode carbon paper were packaged with a frame to form an MEA.

[0099] Test Example 1

[0100] The voltage values ​​of the MEAs of Example 1 and Comparative Examples 1-3 under different humidity conditions were tested respectively, and the testing methods included:

[0101] Polarization curve test: The fuel cell test temperature was set to 85°C, hydrogen was passed through the anode, air was passed through the cathode, the anode to cathode gas stoichiometric ratio was 1.5:2, the anode humidity and cathode humidity were set as required, and the voltage value was recorded as the current changed. The results are shown in Table 1.

[0102] Table 1 Test results

[0103]

[0104]

[0105] According to Table 1, the overall performance of the MEA of Example 1 is improved compared with that of Comparative Examples 1-3, and the sensitivity in dry and wet states is also improved.

[0106] The changes in the catalyst layer of the membrane electrode provided in Example 1 and Comparative Example 1 after long-term operation were tested. Figure 2 It can be seen that after long-term operation of Example 1, the thickness of the overall catalytic layer changes little, and the "Pt band" formed by the Pt particles in the proton exchange membrane has little effect; according to Figure 3 It can be seen that the thickness of the cathode catalyst layer of Comparative Example 1 is significantly reduced after long-term operation, indicating that the carbon corrosion of the cathode is relatively serious. At the same time, the "Pt band" phenomenon is very obvious, indicating that the Pt loss phenomenon is very serious.

[0107] The comparison shows that the MEA provided in this application can effectively improve the life and safety of the fuel cell.

[0108] The above are only specific embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A membrane electrode for a fuel cell, the fuel cell having a hydrogen outlet and a hydrogen inlet, the membrane electrode comprising a cathode diffusion layer, a cathode catalyst layer, a proton exchange membrane, an anode catalyst layer and an anode diffusion layer stacked in sequence, characterized in that: The membrane electrode has a first region and a second region arranged in sequence along the flow direction of hydrogen, the first region corresponds to the hydrogen inlet, and the second region corresponds to the hydrogen outlet; The contact angle of the cathode catalyst layer in the second region is greater than the contact angle of the cathode catalyst layer in the first region; The contact angle of the cathode catalyst layer in the second region is greater than the contact angle of the cathode diffusion layer, and the contact angle of the cathode catalyst layer in the first region is less than the contact angle of the cathode diffusion layer.

2. The membrane electrode according to claim 1, characterized in that: Taking the area of ​​the cathode catalyst layer as the catalytically active region area of ​​the membrane electrode, the first region accounts for 40%-60% of the catalytically active region area, and the second region accounts for 40%-60% of the catalytically active region area.

3. The membrane electrode according to claim 1, characterized in that: The contact angle of the anode catalyst layer in the second region is greater than the contact angle of the anode diffusion layer, and the contact angle of the anode catalyst layer in the first region is less than the contact angle of the anode diffusion layer.

4. The membrane electrode according to claim 1, characterized in that: The difference between the contact angle of the cathode catalyst layer in the second region and the contact angle of the cathode diffusion layer is 5°-10°; and / or, The difference between the contact angle of the cathode catalyst layer in the first region and the contact angle of the cathode diffusion layer is 5°-10°.

5. The membrane electrode according to any one of claims 1 to 4, characterized in that: A contact angle of the cathode catalyst layer in the second region is smaller than a contact angle of the anode catalyst layer in the second region.

6. The membrane electrode according to any one of claims 1 to 4, characterized in that: A contact angle of the cathode catalyst layer in the first region is greater than a contact angle of the anode catalyst layer in the first region.

7. The membrane electrode according to any one of claims 1 to 4, characterized in that: The contact angle of the cathode catalyst layer in the second region is 140°-150°, and the contact angle of the cathode catalyst layer in the first region is 120°-130°.

8. The membrane electrode according to any one of claims 1 to 4, characterized in that: The contact angle of the anode catalyst layer in the second region is 140°-150°, and the contact angle of the anode catalyst layer in the first region is 120°-130°.

9. The membrane electrode according to any one of claims 1 to 4, characterized in that: The contact angles of the cathode diffusion layer and / or the anode diffusion layer are respectively 130°-140°; Optionally, the cathode diffusion layer and the anode diffusion layer are carbon paper layers respectively.

10. A fuel cell, characterized in that: The fuel cell comprises at least one membrane electrode according to any one of claims 1 to 9.

Images