A gas diffusion layer substrate for fuel cell membrane electrode and preparation method thereof

Abstract

The present invention provides a gas diffusion layer substrate for a fuel cell membrane electrode and a preparation method thereof, belonging to the field of fuel cell technology. The preparation method is to place a planar carbon material in a glue solution for immersion; place the immersion product in an electric field environment and at a cathode for high voltage treatment; dry, solidify and carbonize the product after the high voltage treatment to obtain a gas diffusion layer substrate. The thickness direction resistance value of the obtained gas diffusion layer substrate is generally 2-10mΩ·cm 2 The present invention adds conductive carbon material when preparing the gas diffusion layer substrate, and performs high voltage treatment after dipping, so that the gas diffusion layer substrate not only has good conductivity in the in-plane direction, but also maintains a high level of conductivity in the thickness direction, thereby solving the problems of high resistivity and low power generation performance during the power generation process of the fuel cell stack.

Description

Technical Field

[0001] The present invention belongs to the technical field of fuel cells, and in particular relates to a gas diffusion layer substrate for a fuel cell membrane electrode and a preparation method thereof. Background Art

[0002] The basic structure of a solid polymer fuel cell (hereinafter referred to as a fuel cell) consists of a proton exchange membrane, a catalyst, and a gas diffusion layer arranged at the cathode and anode electrodes. The gas diffusion substrate acts as a battery reaction field and a current collector. In addition, in a general fuel cell, a waterproof layer is arranged between the catalyst and the gas diffusion layer substrate, and a bipolar plate is arranged on the other side of the gas diffusion layer substrate.

[0003] In the prior art, carbon paper, a gas diffusion layer substrate for fuel cells, is a porous sheet material formed by bonding dispersed carbon fibers with carbonized materials. Carbon papers with different porosities can be designed to improve the air permeability and drainage of the carbon paper.

[0004] However, the random arrangement of carbon fibers in the current porous carbon paper results in better conductivity in the plane direction but poorer conductivity in the thickness direction, leading to problems such as high resistivity and low power generation performance during the power generation process of the battery stack.

[0005] In view of this, the present invention is proposed. Summary of the invention

[0006] The object of the present invention is to provide a gas diffusion layer substrate for a fuel cell membrane electrode and a preparation method and application thereof, so as to solve the above-mentioned problems.

[0007] In order to achieve the above objectives, the present invention particularly adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a method for preparing a gas diffusion layer substrate for a fuel cell membrane electrode, comprising the following steps:

[0009] The planar carbon material is placed in the glue solution and dipped in glue;

[0010] The dipped product is placed in an electric field environment and placed at a cathode for high voltage treatment;

[0011] The product after the high voltage treatment is dried, solidified and carbonized to obtain the product.

[0012] In a second aspect, the present invention also provides a gas diffusion layer substrate for a fuel cell membrane electrode prepared by the preparation method.

[0013] Beneficial effects of the present invention:

[0014] The present invention adds conductive carbon material when preparing the gas diffusion layer substrate, and performs high voltage treatment after dipping, so that the gas diffusion layer substrate not only has good conductivity in the in-plane direction, but also maintains a high level of conductivity in the thickness direction, thereby solving the problems of high resistivity and low power generation performance during the power generation process of the fuel cell stack. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 It is a structural schematic diagram of the high voltage treatment of the planar carbon material after the resin impregnation of the present invention;

[0017] Figure 2 This is a sample photo of the gas diffusion layer substrate of Example 4 of the present invention.

[0018] Description of reference numerals:

[0019] 1-power supply; 2-anode; 3-cathode; 4-product after dipping. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] When an amount, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper preferred values ​​and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value, regardless of whether the range is disclosed separately. For example, when a range of "1 to 5" is disclosed, the described range should be interpreted as including ranges "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described in this article, unless otherwise stated, the range is intended to include its end values ​​and all integers and fractions within the range.

[0022] In these embodiments, unless otherwise specified, the parts and percentages are all based on mass. The raw material ratios not specified in the present invention can be mixed in any ratio.

[0023] "And / or" is used to indicate that one or both of the stated situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0024] A method for preparing a gas diffusion layer substrate for a fuel cell membrane electrode of the present invention comprises the following steps:

[0025] The planar carbon material is placed in the glue solution and dipped in glue;

[0026] See also Figure 1 The dipped product 4 is placed in an electric field environment and placed on the cathode 3, graphite is used as the anode 2, and the power supply 1 is turned on for high voltage treatment.

[0027] The product after the high voltage treatment is dried, solidified and carbonized to obtain the product.

[0028] In some optional embodiments, the planar carbon material includes one or more of carbon fiber paper, carbon fiber felt or carbon fiber cloth.

[0029] In some optional embodiments, the glue includes a solution of one or more of phenolic resin, polyacrylonitrile resin, chitosan, furan resin or benzoxazine resin.

[0030] In some preferred embodiments, the glue contains conductive carbon material.

[0031] Furthermore, the conductive carbon material includes one or more of carbon nanotubes, nanocarbon fibers, carbon black, graphite or graphene.

[0032] Furthermore, the mass concentration of the conductive carbon material in the glue solution is 0.1-10wt%.

[0033] In some more preferred embodiments, before placing the impregnated product in an electric field environment, the product is subjected to secondary impregnation in an adhesive solution that does not contain the conductive carbon material. The secondary impregnation helps consolidate the conductive carbon material inside the substrate, making it easier to orient along the thickness direction when a voltage is applied, thereby preventing part of the conductive carbon material from detaching from the substrate in the electric field or failing to form an orientation in the thickness direction.

[0034] Furthermore, the dipping time in the glue solution without carbon nanotubes is 1-3 minutes.

[0035] In some optional embodiments, the voltage of the high voltage treatment is 100-2000 V / cm, and the time of the high voltage treatment is 30 seconds-10 minutes. Since the conductive carbon material is oriented along the thickness direction in the electric field, the conductivity in the thickness direction is improved.

[0036] When the applied voltage is lower than 100 V / cm, a lengthy process is required due to the low electric field intensity, which increases the cost.

[0037] When the applied voltage is higher than 2000V / cm, the electric field is too strong, making carbon materials such as carbon fibers and carbon nanotubes prone to conductive breakdown, leading to danger.

[0038] In some preferred embodiments, the voltage of the high voltage treatment is 900-1100 V / cm.

[0039] In some optional embodiments, the curing is to press the dried carbon fiber base paper at 130-200° C. and 0.1-2 MPa.

[0040] In some optional embodiments, the carbonization temperature is 900-1800° C., and the carbonization time is 2-30 min.

[0041] In some optional embodiments, after the carbonization, the carbonized product is further hydrophobized.

[0042] Furthermore, the hydrophobization is to fully contact the carbonized product with a solution, dispersion or suspension of a hydrophobic material, followed by drying and heat treatment.

[0043] The gas diffusion layer substrate for fuel cell membrane electrode prepared by the preparation method of the present invention generally has a thickness direction resistance value of 2-10 mΩ·cm 2 .

[0044] The resistivity in the thickness direction of the substrate prepared in the embodiment of the present invention was tested.

[0045] Thickness direction resistivity test method: The gas diffusion layer substrate was sandwiched between two gold-plated copper electrodes, a pressure of 1 MPa was applied between the copper electrode plates, and then a 10 mA / cm 2 The current density is read, and the voltage drop at this time is read. The resistivity in the thickness direction of the gas diffusion layer substrate is calculated as follows:

[0046] R(Ω·cm 2 )=(voltage drop (V)×sample area (cm 2 )) / Current(A)

[0047] Example 1

[0048] A method for preparing a gas diffusion layer substrate for a fuel cell membrane electrode:

[0049] (1) A 10 wt % aqueous solution of phenolic resin is prepared, and carbon nanotubes are added to form a glue solution so that the mass concentration of the carbon nanotubes is 2 wt %.

[0050] (2) Immerse commercially available carbon fiber paper in the adhesive solution for 30 minutes.

[0051] (3) The impregnated carbon fiber paper is placed in a high voltage electric field environment, where the carbon fiber paper is placed at the cathode and the anode is a graphite electrode, and a voltage of 1000 V / cm is applied for 2 minutes.

[0052] (4) The carbon fiber paper after high voltage treatment was dried at 110 °C, then pressed at 180 °C and 0.5 MPa for 10 min, and then carbonized at 1700 °C for 20 min.

[0053] (5) The carbonized product is immersed in a polytetrafluoroethylene aqueous solution with a mass concentration of 10% for 5 minutes, taken out and dried, and finally sintered at 350° C. to obtain the gas diffusion layer substrate.

[0054] The gas diffusion layer substrate was tested according to the aforementioned thickness direction resistivity test method, and the test data is shown in Table 1.

[0055] Example 2

[0056] A method for preparing a gas diffusion layer substrate for a fuel cell membrane electrode:

[0057] (1) A 10 wt % aqueous solution of phenolic resin is prepared, and graphite is added to make the mass concentration of graphite be 1 wt % to form a glue solution.

[0058] (2) Immerse commercially available carbon fiber paper in the adhesive solution for 30 minutes.

[0059] (3) The impregnated carbon fiber paper is placed in a high voltage electric field environment, wherein the carbon fiber paper is placed at the cathode and the anode is a graphite electrode, and a voltage of 900 V / cm is applied for 5 minutes.

[0060] (4) The carbon fiber paper after high voltage treatment was dried at 110 °C, then pressed at 150 °C and 1 MPa for 10 min, and then carbonized at 1800 °C for 15 min.

[0061] (5) The carbonized product is immersed in a polytetrafluoroethylene aqueous solution with a mass concentration of 10% for 5 minutes, taken out and dried, and finally sintered at 350° C. to obtain the gas diffusion layer substrate.

[0062] The gas diffusion layer substrate was tested according to the aforementioned thickness direction resistivity test method, and the test data is shown in Table 1.

[0063] Example 3

[0064] A method for preparing a gas diffusion layer substrate for a fuel cell membrane electrode:

[0065] (1) preparing an aqueous solution of about 8 wt % polyacrylonitrile resin, adding graphene so that the mass concentration of the graphene is 0.5 wt % to form a glue solution.

[0066] (2) Immerse commercially available carbon fiber felt in the adhesive solution for 30 minutes.

[0067] (3) The carbon fiber felt after the resin impregnation is placed in a high voltage electric field environment, wherein the carbon fiber felt is placed at the cathode and the anode is a graphite electrode, and a voltage of 1100 V / cm is applied for 1 minute.

[0068] (4) The carbon fiber felt after high voltage treatment was dried at 110°C, then pressed at 200°C and 0.2 MPa for 10 min, and then carbonized at 1500°C for 30 min.

[0069] (5) The carbonized product is immersed in a polytetrafluoroethylene aqueous solution with a mass concentration of 10% for 5 minutes, taken out and dried, and finally sintered at 350° C. to obtain the gas diffusion layer substrate.

[0070] The gas diffusion layer substrate was tested according to the aforementioned thickness direction resistivity test method, and the test data is shown in Table 1.

[0071] Example 4

[0072] A method for preparing a gas diffusion layer substrate for a fuel cell membrane electrode:

[0073] (1) Two aqueous solutions of about 10 wt% phenolic resin are prepared, and carbon nanotubes are added to one of the aqueous solutions so that the mass concentration of the carbon nanotubes is 2 wt% to form a glue solution.

[0074] (2) The commercially available carbon fiber paper is immersed in the glue solution containing carbon nanotubes for 30 minutes, then taken out and immersed in another glue solution without carbon nanotubes for 2 minutes.

[0075] (3) The carbon fiber paper after secondary impregnation is placed in a high voltage electric field environment, wherein the carbon fiber paper is placed at the cathode and the anode is a graphite electrode, and a voltage of 1000 V / cm is applied for 2 minutes.

[0076] (4) The carbon fiber paper after high voltage treatment was dried at 110 °C, then pressed at 180 °C and 0.5 MPa for 10 min, and then carbonized at 1700 °C for 20 min.

[0077] (5) The carbonized product was immersed in a polytetrafluoroethylene aqueous solution with a mass concentration of 10% for 5 minutes, taken out and dried, and finally sintered at 350° C. to obtain the gas diffusion layer substrate. The sample photo is shown in Figure 2 .

[0078] The gas diffusion layer substrate was tested according to the aforementioned thickness direction resistivity test method, and the test data is shown in Table 1.

[0079] Example 5

[0080] A method for preparing a gas diffusion layer substrate for a fuel cell membrane electrode:

[0081] (1) Two aqueous solutions of about 10 wt % phenolic resin are prepared, and carbon nanotubes are added to one of the aqueous solutions so that the mass concentration of the carbon nanotubes is 1 wt % to form a glue solution.

[0082] (2) The commercially available carbon fiber paper is immersed in the glue solution containing carbon nanotubes for 30 minutes, then taken out and immersed in another glue solution without carbon nanotubes for 2 minutes.

[0083] (3) The carbon fiber paper after secondary impregnation is placed in a high voltage electric field environment, wherein the carbon fiber paper is placed at the cathode and the anode is a graphite electrode, and a voltage of 900 V / cm is applied for 5 minutes.

[0084] (4) The carbon fiber paper after high voltage treatment was dried at 110 °C, then pressed at 150 °C and 1 MPa for 10 min, and then carbonized at 1800 °C for 15 min.

[0085] (5) The carbonized product is immersed in a polytetrafluoroethylene aqueous solution with a mass concentration of 10% for 5 minutes, taken out and dried, and finally sintered at 350° C. to obtain the gas diffusion layer substrate.

[0086] The gas diffusion layer substrate was tested according to the aforementioned thickness direction resistivity test method, and the test data is shown in Table 1.

[0087] Comparative Example 1

[0088] The difference from Example 1 is that the carbon fiber paper after impregnation is directly subjected to the steps of drying, curing, carbonization and hydrophobization without high voltage treatment. The obtained gas diffusion layer substrate is tested according to the aforementioned thickness direction resistivity test method. The test data are shown in Table 1.

[0089] Comparative Example 2

[0090] The difference from Example 1 is that no carbon nanotubes are added to the glue solution. The obtained gas diffusion layer substrate is tested according to the aforementioned thickness direction resistivity test method. The test data is shown in Table 1.

[0091] Table 1 Performance test of conductive carbon paper obtained in Examples and Comparative Examples

[0092]

[0093] It can be seen from Table 1 that the resistivity of the products obtained in Examples 1-5 is significantly lower than that in Comparative Examples 1 and 2 where no high voltage treatment is performed and no conductive carbon material is added for orientation. Moreover, in Examples 4 and 5 where secondary impregnation is performed, the resistivity of the products obtained is further lower than that in Examples 1 and 2 under the same conditions.

[0094] Please note that the technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, all possible combinations of the technical features in the above embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification. The above embodiments only express several implementation methods of the present application, and their descriptions are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, without departing from the concept of the present application, several variations and improvements can be made, which all belong to the scope of protection of the present application. Therefore, the scope of protection of the patent in this application shall be based on the attached claims.

Claims

1. A method for preparing a gas diffusion layer substrate for a fuel cell membrane electrode, characterized in that: The steps include: The planar carbon material is placed in the glue solution and dipped in glue; The dipped product is placed in an electric field environment and placed at a cathode for high voltage treatment; The product after the high voltage treatment is dried, solidified and carbonized to obtain; The planar carbon material includes one or more of carbon fiber paper, carbon fiber felt or carbon fiber cloth; The glue solution includes a solution of one or more of phenolic resin, polyacrylonitrile resin, chitosan, furan resin or benzoxazine resin; The glue contains conductive carbon material; The voltage of the high voltage treatment is 100-2000 V / cm, and the time of the high voltage treatment is 30 seconds-10 minutes.

2. The preparation method according to claim 1, characterized in that: The conductive carbon material includes one or more of carbon nanotubes, carbon nanofibers, carbon black, graphite or graphene.

3. The preparation method according to claim 2, characterized in that The mass concentration of the conductive carbon material in the glue solution is 0.1-10 wt %.

4. The preparation method according to claim 2 or 3, characterized in that: Before placing the impregnated product in an electric field environment, the product is impregnated for a second time in an adhesive solution that does not contain the conductive carbon material.

5. The preparation method according to claim 4, characterized in that: The time of dipping in the glue solution without carbon nanotubes is 1-3 minutes.

6. The preparation method according to claim 1, characterized in that The voltage of the high voltage treatment is 900-1100 V / cm.

7. The preparation method according to claim 1, characterized in that: The curing is to press the dried carbon fiber base paper at 130-200°C and 0.1-2MPa; And / or, the carbonization temperature is 900-1800° C., and the carbonization time is 2-30 min.

8. The preparation method according to claim 1, characterized in that: After the carbonization, the carbonized product is further hydrophobized.

9. The preparation method according to claim 8, characterized in that: The hydrophobization is to fully contact the carbonized product with a solution, dispersion or suspension of a hydrophobic material, followed by drying and heat treatment.

10. A gas diffusion layer substrate for a fuel cell membrane electrode prepared by the preparation method according to any one of claims 1 to 9.

Images