Microporous layer slurry for regulating penetration depth, gas diffusion layer and preparation method

Abstract

The present application relates to the field of fuel cell materials, and in particular to a microporous layer slurry, a gas diffusion layer and a preparation method for regulating penetration depth; the raw materials of the microporous layer slurry include: a dispersant, conductive carbon black, a hydrophobic agent and an acidic organic thickener; the mass ratio of the acidic organic thickener to the microporous layer slurry is 0.05 to 0.2; by introducing the acidic organic thickener into the microporous layer slurry and limiting the mass ratio between the acidic organic thickener and the microporous layer slurry as a whole, by regulating the proportion of the acidic organic thickener, the resistance of the microporous layer slurry penetration process can be adjusted, and in the later process of preparing the gas diffusion layer, the acidic organic thickener can be used in combination with heating to accelerate the loss of water in the microporous layer slurry, thereby further preventing the microporous layer slurry from penetrating into the substrate layer, thereby achieving effective control of the penetration depth of the microporous layer slurry.

Description

Technical Field

[0001] The present application relates to the field of fuel cell materials, and in particular to a microporous layer slurry for regulating penetration depth, a gas diffusion layer and a preparation method thereof. Background Art

[0002] A fuel cell is a chemical device that converts the chemical energy of a fuel directly into electrical energy, also known as an electrochemical generator. It is the fourth power generation technology after hydroelectric power generation, thermal power generation, and atomic power generation. Since fuel cells convert part of the Gibbs free energy in the chemical energy of a fuel into electrical energy through electrochemical reactions, they are not limited by the Carnot cycle effect and therefore have high efficiency. In addition, fuel cells use fuel and oxygen as raw materials and have no mechanical transmission parts, so they emit very little harmful gas and have a long service life. It can be seen that from the perspective of energy conservation and ecological protection, fuel cells are the most promising power generation technology.

[0003] The main structure of a fuel cell is a membrane electrode, which is mainly composed of a catalyst layer and a gas diffusion layer, wherein the diffusion layer can be divided into a base layer and a microporous layer. The base layer is in direct contact with the catalyst layer, and plays the role of supporting the microporous layer and the catalyst layer, collecting current, conducting gas and discharging water. The main materials used are carbon paper, carbon cloth, etc., and the gas diffusion layer plays the role of transmitting the reaction gas and the water generated on the cathode catalyst layer side; the gas diffusion layer is mainly composed of a microporous layer and a base layer, but experiments at this stage show that the depth of penetration of the microporous layer into the base layer has a certain influence on the performance of the gas diffusion layer, and currently the microporous layer is mainly formed by the dispersant in the microporous layer slurry directly entering the base layer, and most of the dispersant is an organic solvent, and it is difficult to control the penetration depth of the microporous layer slurry by controlling the dispersant. Therefore, how to provide a microporous layer slurry that can adjust the depth of penetration of the microporous layer into the base layer is a technical problem that urgently needs to be solved. Summary of the invention

[0004] The present application provides a microporous layer slurry, a gas diffusion layer and a preparation method for regulating the penetration depth, so as to solve the technical problem in the prior art that the penetration depth of the microporous layer into the substrate layer is difficult to regulate. Through the microporous layer slurry, the penetration depth of the microporous layer into the substrate layer can be effectively regulated.

[0005] In a first aspect, the present application provides a microporous layer slurry for regulating penetration depth, wherein the raw materials of the microporous layer slurry include: a dispersant, conductive carbon black, a hydrophobic agent, and an acidic organic thickener;

[0006] The mass ratio of the acidic organic thickener to the microporous layer slurry is 0.05 to 0.2.

[0007] Optionally, the acidic organic thickener includes a dodecyl sulfate thickener.

[0008] Optionally, the acidic organic thickener includes an acid solution of a self-thickening polymer and sodium dodecyl sulfate.

[0009] Optionally, the dispersant includes at least one of ethanol, isopropanol, ethylene glycol and hexafluoroisopropanol; and / or,

[0010] The water repellent comprises at least one of polytetrafluoroethylene, polyvinylidene fluoride and a copolymer of tetrafluoroethylene and ethylene.

[0011] Optionally, the conductive carbon black includes at least one of acetylene black, Vulcan XC-72, Black pearls, carbon nanotubes and graphene powder.

[0012] In a second aspect, the present application provides a method for preparing the microporous layer slurry according to the first aspect, the method comprising:

[0013] The dispersant and the conductive carbon black are mixed, and first stirred and ultrasonicated to obtain a carbonaceous slurry;

[0014] The water repellent and the acidic organic thickener are added to the carbonaceous slurry, and a second stirring and grinding process is performed to obtain a microporous layer slurry.

[0015] Optionally, the time for the first stirring, the second stirring, the ultrasound and the grinding is 25 min to 35 min respectively.

[0016] In a third aspect, the present application provides a gas diffusion layer, which is prepared by printing the microporous layer slurry described in the first aspect on a base layer.

[0017] Optionally, the weight content of the water repellent in the microporous layer is 15% to 35%.

[0018] In a fourth aspect, the present application provides a method for preparing the gas diffusion layer according to the third aspect, the method comprising:

[0019] The base layer is subjected to a hydrophobic treatment;

[0020] Printing the microporous layer slurry described in the first aspect on the surface of the hydrophobic treated substrate layer, and then drying and baking, and heat-insulating to obtain a gas diffusion layer;

[0021] The conductive carbon black loading in the gas diffusion layer is 0.8 mg / cm 2 ~3mg / cm 2 .

[0022] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0023] The embodiment of the present application provides a microporous layer slurry for regulating penetration depth. An acidic organic thickener is introduced into the microporous layer slurry, and the mass ratio between the acidic organic thickener and the microporous layer slurry as a whole is limited. Since the acidic organic thickener can utilize the hydrophobic side chains in the thickener system under acidic conditions to combine with hydrogen bonds in water to increase the flow volume of the microporous layer slurry, thereby increasing the viscosity of the system, so that the penetration process of the microporous layer slurry on the base layer is hindered. Therefore, by regulating the proportion of the acidic organic thickener, the resistance of the microporous layer slurry penetration process can be adjusted. In the later process of preparing the gas diffusion layer, the acidic organic thickener can be used in combination with heating to accelerate the loss of water in the microporous layer slurry, thereby further preventing the microporous layer slurry from penetrating into the base layer, thereby achieving effective control of the penetration depth of the microporous layer slurry. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0025] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0026] Figure 1 A schematic flow chart of a method for preparing a microporous layer slurry provided in an embodiment of the present application;

[0027] Figure 2 A schematic flow chart of a method for preparing a gas diffusion layer provided in an embodiment of the present application;

[0028] Figure 3 A schematic diagram showing the comparison of polarization curves of gas diffusion layer samples provided in the embodiments of the present application;

[0029] Figure 4 This is an electron microscope image of the penetration depth of the microporous layer slurry in the gas diffusion layer sample provided in the embodiment of the present application, wherein: Figure 4 A is an electron microscope image of the penetration depth of the microporous layer slurry in the gas diffusion layer sample provided in Example 2 of the present application, Figure 4 B is an electron microscope image of the penetration depth of the microporous layer slurry in the gas diffusion layer sample provided in Comparative Example 2 of the present application, Figure 4 C is an electron microscope image of the penetration depth of the microporous layer slurry in the gas diffusion layer sample provided in Example 1 of the present application, Figure 4 D is an electron microscope image of the penetration depth of the microporous layer slurry in the gas diffusion layer sample provided in Comparative Example 1 of the application, Figure 4E is an electron microscope image of the penetration depth of the microporous layer slurry in the gas diffusion layer sample provided in Example 3 of the present application. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0031] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0032] The creative thinking of this application is:

[0033] Experiments at this stage show that the depth of penetration of the microporous layer into the substrate layer has a certain influence on the performance of the gas diffusion layer: when the penetration depth is too large, the gas diffusion layer is flooded with water in large quantities, and the accumulated water acts as a back pressure, causing severe capillary condensation in the MPL penetration area, thereby depriving the supply of reactant gas and seriously affecting the performance of the membrane electrode;

[0034] When the penetration depth is small, the drainage is not optimal and the air permeability will also be affected to a certain extent. At present, the microporous layer is mainly formed by the dispersant in the microporous layer slurry directly entering the base layer, and most of the dispersants are organic solvents. It is difficult to control the penetration depth of the microporous layer slurry by controlling the dispersant. Therefore, how to provide a microporous layer slurry that can adjust the penetration depth of the microporous layer into the base layer is a technical problem that urgently needs to be solved.

[0035] The embodiment of the present application provides a microporous layer slurry for regulating penetration depth, wherein the raw materials of the microporous layer slurry include: a dispersant, conductive carbon black, a hydrophobic agent, and an acidic organic thickener;

[0036] The mass ratio of the acidic organic thickener to the microporous layer slurry is 0.05 to 0.2.

[0037] In the embodiment of the present application, the positive effect of controlling the mass ratio of the acidic organic thickener to the microporous layer slurry to 0.05-0.2 is that within the range of this mass ratio, the thickening effect of the acidic organic thickener can be guaranteed, while at the same time preventing the thickener from affecting the uniformity of the microporous layer slurry dispersed on the base layer.

[0038] In some optional embodiments, the acidic organic thickener includes a dodecyl sulfate thickener.

[0039] In the embodiments of the present application, the specific type of the acidic organic thickener is controlled. Since the dodecyl sulfate thickener has good water solubility and multiple hydrophobic side chains, it will combine with hydrogen bonds in water to increase the flow volume of the microporous layer slurry. Therefore, it can effectively increase the viscosity of the microporous layer slurry, further prevent the microporous layer slurry from penetrating into the base layer, and thus achieve effective control of the penetration depth of the microporous layer slurry.

[0040] In some optional embodiments, the acidic organic thickener includes a self-thickening polymer complexed with an acid solution of sodium dodecyl sulfate (ADD-SDS).

[0041] In the embodiments of the present application, the specific type of the acidic organic thickener is controlled. On the one hand, the thickening degree of the microporous layer slurry can be improved by combining the self-thickening polymer with the acid solution of sodium dodecyl sulfate. On the other hand, the self-thickening polymer with the acid solution of sodium dodecyl sulfate is combined with heating to accelerate the loss of water in the microporous layer slurry, thereby further preventing the microporous layer slurry from penetrating into the base layer, thereby achieving effective control of the penetration depth of the microporous layer slurry.

[0042] In some optional embodiments, the dispersant includes at least one of ethanol, isopropanol, ethylene glycol and hexafluoroisopropanol; and / or,

[0043] The water repellent comprises at least one of polytetrafluoroethylene, polyvinylidene fluoride and a copolymer of tetrafluoroethylene and ethylene.

[0044] In the embodiments of the present application, the specific type of dispersant is limited. On the one hand, it can ensure that the conductive carbon black is dispersed by the dispersant and evenly distributed in the microporous layer slurry, thereby ensuring the uniform distribution of the pore size on the gas diffusion layer. On the other hand, through the joint action of the dispersant and the acidic organic thickener, the acidic organic thickener can be evenly dispersed in the microporous layer slurry, thereby ensuring its thickening effect.

[0045] By limiting the specific type of the hydrophobic agent, on the one hand, the hydrophobicity of the microporous layer slurry can be improved, and on the other hand, the acidic organic thickener can be evenly dispersed in the microporous layer slurry by combining with the dispersant, thereby ensuring its thickening effect.

[0046] In some optional embodiments, the conductive carbon black includes at least one of acetylene black, Vulcan XC-72, Blackpearls, carbon nanotubes and graphene powder.

[0047] In the embodiments of the present application, the specific types of conductive carbon black are limited to include most carbon black particles with good conductivity, while ensuring that they can be evenly dispersed in the dispersant and hydrophobic agent solutions, thereby ensuring that the acidic organic thickener is evenly dispersed in the microporous layer slurry, thereby ensuring its thickening effect.

[0048] like Figure 1 As shown, based on a general inventive concept, an embodiment of the present application provides a method for preparing the microporous layer slurry, the method comprising:

[0049] S1. mixing the dispersant and the conductive carbon black, and performing a first stirring and ultrasound to obtain a carbonaceous slurry;

[0050] S2. Add the water repellent and the acidic organic thickener to the carbonaceous slurry, and perform a second stirring and grinding to obtain a microporous layer slurry.

[0051] In the embodiment of the present application, a first stirring and ultrasound are used to evenly mix the conductive carbon black and the dispersant to ensure that the conductive carbon black is evenly dispersed, and then the carbon-containing slurry, the hydrophobic agent and the acidic organic thickener are subjected to a second stirring and grinding, which can ensure that the carbon-containing slurry, the hydrophobic agent and the acidic organic thickener are fully mixed to obtain a microporous layer slurry with uniform component distribution.

[0052] This method is a method for preparing the above-mentioned microporous layer slurry. The specific composition of the microporous layer slurry can refer to the above-mentioned embodiment. Since this method adopts part or all of the technical solutions of the above-mentioned embodiment, it at least has all the beneficial effects brought by the technical solutions of the above-mentioned embodiment, which will not be repeated here one by one.

[0053] In some optional embodiments, the time for the first stirring, the second stirring, the ultrasound and the grinding is 25 min to 35 min respectively.

[0054] In the embodiments of the present application, the specific time of the first stirring, the second stirring, the ultrasound and the grinding is controlled to ensure that the components of the microporous layer slurry are fully mixed to obtain a microporous layer slurry with uniform component distribution.

[0055] In some optional embodiments, the weight content of the water repellent in the microporous layer is 15% to 35%.

[0056] In the embodiment of the present application, the positive effect of controlling the weight content of the hydrophobic agent in the microporous layer to 15% to 35% is that within this content range, the hydrophobicity of the microporous layer can be ensured, thereby ensuring the normal drainage function of the gas diffusion layer.

[0057] Based on a general inventive concept, an embodiment of the present application provides a gas diffusion layer, wherein the gas diffusion layer is prepared by printing the microporous layer slurry on a base layer.

[0058] In the embodiment of the present application, the printing method can be screen printing, spray printing and smear printing.

[0059] The gas diffusion layer is realized based on the above-mentioned microporous layer slurry. The specific composition of the microporous layer slurry can refer to the above-mentioned embodiment. Since the gas diffusion layer adopts part or all of the technical solutions of the above-mentioned embodiments, it has at least all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be described one by one here.

[0060] like Figure 2 As shown, based on a general inventive concept, an embodiment of the present application provides a method for preparing the gas diffusion layer, the method comprising:

[0061] S1. Treat the substrate with hydrophobic treatment;

[0062] S2. Printing the microporous layer slurry on the surface of the base layer after hydrophobic treatment, and then drying and baking, and heat preservation to obtain a gas diffusion layer;

[0063] The conductive carbon black loading in the gas diffusion layer is 0.8 mg / cm 2 ~3mg / cm 2 .

[0064] In the embodiment of the present application, the base layer is subjected to a hydrophobic treatment to ensure complete adhesion between the microporous layer slurry and the base layer, and the base layer printed with the microporous layer slurry is dried and baked to ensure rapid water loss of the acidic organic thickener, thereby enabling the depth of penetration of the microporous layer slurry into the base layer to be controlled by controlling the drying and baking temperatures.

[0065] The conductive carbon black loading in the gas diffusion layer is controlled to be 0.8 mg / cm 2 ~3mg / cm 2 The positive effect is that within the range of the loading, it can ensure that there is enough conductive carbon black in the gas diffusion layer, thereby ensuring the conductive performance of the gas diffusion layer.

[0066] This method is a method for preparing the above-mentioned gas diffusion layer. The specific composition of the gas diffusion layer can refer to the above-mentioned embodiment. Since this method adopts part or all of the technical solutions of the above-mentioned embodiment, it at least has all the beneficial effects brought by the technical solutions of the above-mentioned embodiment, which will not be described one by one here.

[0067] The present application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are intended only to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods for which specific conditions are not specified in the following examples are usually measured according to national standards. If there is no corresponding national standard, then the conditions recommended by the manufacturer are followed.

[0068] Example 1

[0069] The preparation process of the gas diffusion layer is as follows:

[0070] 1. Preparation of microporous layer slurry: isopropanol and Vulcan XC-72 carbon powder were mixed in a mass ratio of 3:1, and then magnetically stirred for 30 minutes to obtain slurry A. 0.5 mL of ADD-SDS (accounting for 0.15 of the total mass of the microporous layer slurry) and PTFE emulsion with a solid content of 60% were added to the slurry A dispersed to a certain extent, and magnetic stirring was continued for 30 minutes, and then ball milling was performed for 30 minutes to obtain a uniformly dispersed microporous layer slurry;

[0071] 2. Preparation of gas diffusion layer: The base layer material is immersed in a 15% PTFE solution, immersed for 30 minutes, and then placed in an oven and dried at 60°C for 1 hour. This step is repeated 4 times until the PETF content in the pretreated carbon paper is 5.5%;

[0072] The obtained microporous layer slurry was coated on the surface of the hydrophobic treated base layer by screen printing, and then taken out and placed in an oven to dry at 60°C for 1 hour, and then placed in a box-type resistance furnace and heated to 300°C for 3 hours, and kept warm for 0.5 hours to obtain the final gas diffusion layer.

[0073] Example 2

[0074] Comparing Example 2 with Example 1, the difference between Example 2 and Example 1 is:

[0075] 0.1 mL of additive ADD-SDS (accounting for 0.05 of the total mass of the microporous layer slurry) was added.

[0076] Example 3

[0077] Comparing Example 3 with Example 1, the difference between Example 3 and Example 1 is:

[0078] 0.8 mL of additive ADD-SDS (0.20 of the total mass of the microporous layer slurry) was added.

[0079] Comparative Example 1

[0080] Comparative Example 1 and Example 1 are compared. The difference between Comparative Example 1 and Example 1 is:

[0081] Without adding the additive ADD-SDS, the preparation process of the gas diffusion layer is:

[0082] 1. Preparation of microporous layer slurry: Mix isopropyl alcohol and Vulcan XC-72 carbon powder in a mass ratio of 3:1, add magnetic stirring for 30 minutes, ultrasonic for 30 minutes, add 60% polytetrafluoroethylene emulsion to the dispersed slurry, stir it magnetically for 30 minutes, and ball mill to obtain a uniform microporous layer slurry;

[0083] 2. Preparation of gas diffusion layer: The obtained microporous layer slurry is coated on the surface of the hydrophobic treated substrate by screen printing, and then taken out and placed in an oven to dry at 60°C for 1 hour, and then placed in a box-type resistance furnace and heated to 300°C for 3 hours, and kept warm for 0.5 hours to obtain the final gas diffusion layer.

[0084] Comparative Example 2

[0085] Comparative Example 2 and Example 1 are compared. The difference between Comparative Example 2 and Example 1 is:

[0086] Add 1 mL of additive ADD-SDS, and the preparation process of the gas diffusion layer is as follows:

[0087] 1. Preparation of microporous layer slurry: Mix isopropanol solvent and Vulcan XC-72 carbon powder in a mass ratio of 3:1, and then perform magnetic stirring to obtain slurry A. Add 1 mL of ADD-SDS and PTFE emulsion with a solid content of 60% to the slurry A dispersed to a certain extent, continue magnetic stirring, and then perform ball milling to obtain a uniformly dispersed microporous layer slurry;

[0088] 2. Preparation of gas diffusion layer: The obtained microporous layer slurry is coated on the surface of the hydrophobic treated substrate by screen printing, and then taken out and placed in an oven to dry at 60°C for 1 hour, and then placed in a box-type resistance furnace and heated to 300°C for 3 hours, and kept warm for 0.5 hours to obtain the final gas diffusion layer.

[0089] Membrane electrode performance test: Select the same CCM, match different samples, and place them on a single cell test bench for polarization curve test. The test bench model is SCRIBNER 850e, and the current density is set to 2000. The results are as follows: Figure 3 shown.

[0090] Air permeability test: The air permeability of different gas diffusion layers was characterized using an air permeability tester. The results are shown in Table 1.

[0091] Water permeability test: The water permeability of different gas diffusion layers was characterized using a bubble pressure filter membrane pore size analyzer. The results are shown in Table 1.

[0092] SEM test: Through cross-sectional electron microscope observation, the slurry penetration depth is measured. The results are as follows: Figure 4 shown.

[0093] Table 1 Data of air permeability, water permeability and contact angle of gas diffusion layer samples of various embodiments and comparative examples

[0094]

[0095]

[0096] Combined with Table 1, Figure 3 and Figure 4 From the data:

[0097] The performance of Example 1 is better than that of Comparative Example 1 and Comparative Example 2. At 2000 current density, the voltage of Example 1 is 0.587V, the voltage of Example 2 is 0.558V, and the voltage of Example 3 is 0.532V, which are all higher than the v0.528 voltage of Comparative Example 1 and the 0.530V voltage of Comparative Example 2. This may be due to the different penetration depths. For samples with more appropriate penetration depths, water is more easily removed from the pores due to the action of capillary force. Under high current density, although the water production is greater, the performance will be better due to the excellent drainage performance. It can be seen from the scanning electron microscope that the depth of Example 1 is 21μm ( Figure 4 C), the depth of Example 2 is 26 μm ( Figure 4 A), the depth of Example 3 is 9.2 μm ( Figure 4 E), the depth of comparative example 1 is 38 μm ( Figure 4 D), the depth of comparative example 2 is 8.1 μm ( Figure 4 B), which supports this conjecture.

[0098] Therefore, the gas diffusion layer prepared by using the microporous layer slurry of the present application not only has excellent drainage performance, but also has reduced internal resistance. At the same time, when the same CCM is used for MEA preparation, the performance of the gas diffusion layer is improved compared with the commercial gas diffusion layer.

[0099] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the range description from 1 to 6 should be considered to have specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0100] In this application, unless otherwise specified, directional words such as "upper" and "lower" used refer specifically to the directions of the drawings in the accompanying drawings. In addition, in the description of the specification of this application, the terms "include", "comprise", etc. mean "including but not limited to".

[0101] In this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. In this article, "and / or" describes the association relationship of associated objects, indicating that there can be three relationships, for example, A and / or B, which can represent: A exists alone, A and B exist at the same time, and B exists alone. Wherein A, B can be singular or plural. In this article, "at least one" refers to one or more, and "multiple" refers to two or more. "At least one", "the following at least one (individual)" or similar expressions refer to any combination of these items, including any combination of single (individual) or plural (individual). For example, "at least one (individual) of a, b, or c", or "at least one (individual) of a, b, and c", can all represent: a, b, c, ab (i.e. a and b), ac, bc, or abc, wherein a, b, c can be single or multiple respectively.

[0102] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A microporous layer slurry for regulating penetration depth, characterized in that: The raw materials of the microporous layer slurry include: dispersant, conductive carbon black, hydrophobic agent and acidic organic thickener; The mass ratio of the acidic organic thickener to the microporous layer slurry is 0.05-0.2, and the acidic organic thickener is an acid solution of a self-thickening polymer and a composite sodium dodecyl sulfate.

2. The microporous layer slurry according to claim 1, characterized in that: The dispersant comprises at least one of ethanol, isopropanol, ethylene glycol and hexafluoroisopropanol; and / or, The water repellent comprises at least one of polytetrafluoroethylene, polyvinylidene fluoride and a copolymer of tetrafluoroethylene and ethylene.

3. The microporous layer slurry according to claim 1, characterized in that: The conductive carbon black includes at least one of acetylene black, Vulcan XC-72, Black pearls, carbon nanotubes and graphene powder.

4. A method for preparing the microporous layer slurry according to any one of claims 1 to 3, characterized in that: The method comprises: The dispersant and the conductive carbon black are mixed, and first stirred and ultrasonicated to obtain a carbonaceous slurry; The water repellent and the acidic organic thickener are added to the carbonaceous slurry, and a second stirring and grinding process is performed to obtain a microporous layer slurry.

5. The method according to claim 4, characterized in that The time for the first stirring, the second stirring, the ultrasound and the grinding is 25 min to 35 min respectively.

6. A gas diffusion layer, characterized in that: The gas diffusion layer comprises a microporous layer and a base layer, and the microporous layer is prepared by printing the microporous layer slurry according to any one of claims 1 to 3 on the surface of the base layer.

7. The gas diffusion layer according to claim 6, characterized in that: The weight content of the water repellent in the microporous layer is 15% to 35%.

8. A method for preparing the gas diffusion layer according to claim 6 or 7, characterized in that: The method comprises: The base layer is subjected to a hydrophobic treatment; Printing the microporous layer slurry as claimed in any one of claims 1 to 5 on the surface of the hydrophobic treated substrate layer, followed by drying and calcining, and heat preservation to obtain a gas diffusion layer; The conductive carbon black loading in the gas diffusion layer is 0.8 mg / cm 2 ~3mg / cm 2 .

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