阅读说明：本技术 气体扩散层、其制备方法、以及相应的膜电极组件以及燃料电池 (Gas diffusion layer, method for producing same, and corresponding membrane electrode assembly and fuel cell ) 是由 沈星汉 于 2019-12-31 设计创作，主要内容包括：本发明公开了一种气体扩散层,制备方法、膜电极组件以及燃料电池,本发明技术方案设置所述气体扩散层疏水处理工艺中所用的浆料中特别添加了含有儿茶酚或含有邻苯二酚结构化合物的添加剂,特别是盐酸多巴胺。这样,能够显著气体扩散层材料的均一性、疏水性、导电性和耐久性,同时用该气体扩散层制备的燃料电池电堆性能有显著提升。(The invention discloses a gas diffusion layer, a preparation method, a membrane electrode assembly and a fuel cell. Therefore, the uniformity, hydrophobicity, conductivity and durability of the gas diffusion layer material can be obviously improved, and the performance of the fuel cell stack prepared by the gas diffusion layer is obviously improved.)

1. A gas diffusion layer for a fuel cell, comprising a gas diffusion layer substrate, and a water repellent treatment slurry coated on the surface of the gas diffusion layer; wherein the additive containing catechol or catechol structure compound is added into the hydrophobic treatment slurry.

2. A production method for producing the gas diffusion layer according to claim 1, comprising:

the preparation method of the hydrophobic treatment slurry comprises the following steps: mixing slurry comprising water, polytetrafluoroethylene solution, isopropanol, ethanol, catechol or catechol-containing compound in proportion, dispersing and mixing with a homogenizer, and further dispersing with an ultrasonic cleaner;

immersing the gas diffusion layer substrate in the slurry;

taking the gas diffusion layer base material out of the slurry, and heating and drying the gas diffusion layer base material;

repeating the steps for 2-8 times in the preparation process of the gas diffusion layer; and

and (4) coating the microporous layer on the gas diffusion layer substrate subjected to the hydrophobic treatment.

3. A membrane electrode assembly, comprising: a cathode-side gas diffusion layer, a cathode-side catalyst layer, a proton exchange membrane, an anode-side catalyst layer, and an anode-side gas diffusion layer which are stacked in this order; wherein the cathode-side gas diffusion layer comprises the gas diffusion layer of claim 1; the anode-side gas diffusion layer comprising the gas diffusion layer according to claim 1.

4. A fuel cell, characterized in that the fuel cell comprises: a fuel cell stack comprising a membrane electrode assembly, a plate, a collector, an insulator plate, a seal structure, and an end plate according to claim 3.

Technical Field

The invention relates to the technical field of fuel cells, in particular to a gas diffusion layer, a preparation method, a membrane electrode assembly and a fuel cell.

Background

As an alternative energy technology, fuel cells have attracted considerable attention and continued research and development due to their characteristics of convenience in starting, high energy density, zero emission, and high energy conversion efficiency, and have been widely used as power sources for automobiles, communication base stations, portable electric tools, and the like. The power supply system for commercial use has the outstanding advantages of long enough service life and high energy density, such as application to standby power supplies, passenger vehicles, material transport vehicles, submarines and the like.

Proton exchange membrane fuel cells are the most mature, closest to commercially available fuel cells. The gas diffusion layer mainly plays five roles in the membrane electrode of the proton exchange membrane fuel cell: the first step, supporting a proton exchange membrane and a catalytic layer; secondly, transmitting the cathode and anode reaction gas in the flow field flow channel to the surface of the catalyst through molecular diffusion and Knudsen; third, electrons generated from the catalytic layer are transferred to the plate. Fourthly, water produced by the catalyst layer is transmitted to the flow channel for timely removal through capillary effect, concentration diffusion and the like in the gas diffusion layer, and mass transfer polarization is avoided. Fifth, the method comprises the following steps: sometimes, the gas diffusion layer performs a function of attaching the catalyst layer, and the catalyst layer is directly coated on the surface of the gas diffusion layer. The commonly used gas diffusion layer uses carbon fiber as a raw material, raw paper is prepared by a wet papermaking method or a non-woven dry method, and then raw paper of the gas diffusion layer is prepared by carbonization and graphitization engineering. Because the surface of the carbon fiber is hydrophilic or not very hydrophobic, water generated in the fuel cell or input water is accumulated in the gas diffusion layer and is difficult to discharge, so that reaction gas cannot be transmitted to the surface of the catalyst in time, severe mass transfer polarization is generated, and the performance of the cell is reduced.

From the above description, how to ensure the gas transmission balance in the fuel cell to ensure the fuel cell has better performance is a problem to be solved urgently in the fuel cell field.

Disclosure of Invention

In order to solve the problems, the technical scheme of the invention provides a gas diffusion layer, a preparation method, a membrane electrode assembly and a fuel cell, which can ensure the gas transmission balance in the fuel cell.

In order to realize the above problem, the present invention provides the following technical solutions:

a gas diffusion layer for a fuel cell, wherein an additive containing catechol or a compound having a catechol structure (particularly dopamine hydrochloride) is added to a slurry used in a hydrophobic treatment process.

And dopamine hydrochloride is added into slurry used in the process of hydrophobic treatment of the gas diffusion layer.

The slurry used in the hydrophobic process of the gas diffusion layer consists of water, polytetrafluoroethylene solution, isopropanol, ethanol, catechol or a compound containing a catechol structure (particularly dopamine hydrochloride) and the like.

The dosage of the catechol or the additive containing catechol structural compound (especially dopamine hydrochloride) accounts for 0.05-30% of the total mass of the slurry.

The thickness of the gas diffusion layer is 10 μm to 500 μm.

The invention also includes a method for preparing the gas diffusion layer, comprising:

the slurry for the hydrophobic treatment process, namely the configuration of the hydrophobic treatment slurry, is prepared by mixing water, a polytetrafluoroethylene solution, isopropanol, ethanol, catechol or a slurry containing catechol structural compounds (particularly dopamine hydrochloride) and the like according to a proportion, dispersing and mixing the mixture by a homogenizer, and further dispersing the mixture uniformly by an ultrasonic cleaner.

The gas diffusion layer substrate was immersed in the slurry described above.

The gas diffusion layer substrate was taken out of the slurry and then dried by heating.

The above steps are repeated 2-8 times in the gas diffusion layer preparation process.

And (4) coating the microporous layer on the gas diffusion layer substrate subjected to the hydrophobic treatment.

The preparation method comprises the following steps:

the preparation of the slurry for the hydrophobic treatment process comprises the steps of mixing the slurry consisting of water, a polytetrafluoroethylene solution, isopropanol, ethanol, dopamine hydrochloride and the like according to a proportion, dispersing, mixing and dispersing uniformly by using a homogenizer, and further dispersing uniformly by using an ultrasonic cleaner.

The gas diffusion layer substrate was immersed in the slurry described above.

The gas diffusion layer substrate was taken out of the slurry and then dried by heating.

The above steps are repeated 2-8 times in the gas diffusion layer preparation process.

And (4) coating the microporous layer on the gas diffusion layer substrate subjected to the hydrophobic treatment.

According to the preparation method of the gas diffusion layer, the using amount of catechol or an additive containing catechol structural compound (particularly dopamine hydrochloride) accounts for 0.05-30% of the total mass of the slurry.

The preparation method of the gas diffusion layer comprises the steps of taking out slurry and then heating and drying, wherein the heating temperature range is 200-300 ℃, and normal pressure drying or vacuum drying can be selected.

The preparation method of the gas diffusion layer comprises the step of preparing the gas diffusion layer with the thickness of 10-500 mu m.

The preparation method of the gas diffusion layer comprises the following steps:

a cathode-side gas diffusion layer, a cathode-side catalyst layer, a proton exchange membrane, an anode-side catalyst layer, and an anode-side gas diffusion layer which are stacked in this order;

wherein the cathode-side gas diffusion layer is prepared by the hydrophobic treatment process as described in any one of examples 1 to 5; the anode-side gas diffusion layer was prepared by the hydrophobic treatment process according to any one of examples 1 to 5

The present invention also includes a fuel cell comprising: the fuel cell pile is composed of membrane electrode, polar plate, current collecting plate, insulating plate, sealing structure and end plate.

The slurry selected by the invention is particularly added with an additive containing catechol or a catechol structure compound, particularly dopamine hydrochloride. Aromatic ring functional groups in the substance are units with pi-pi conjugated structures, are similar to carbon-carbon chemical bond structures on the surfaces of carbon fibers subjected to high-temperature graphitization treatment, can be well contacted and dispersed, and meanwhile, an adjacent dihydroxy structure on an aromatic ring can be well contacted with a polytetrafluoroethylene molecular chain and is also well mutually soluble with alcohol solvents in a polytetrafluoroethylene solution. Particularly, dopamine hydrochloride containing a catechol structure has an amino acid structure functional group, and can further increase the bonding between a polytetrafluoroethylene solution and carbon fibers. The functional group with the amino acid structure can be naturally decomposed to produce gas to be discharged when being subjected to high-temperature treatment in the later process, and is a pore-forming agent which can increase the porosity of the gas diffusion layer material. In fact, the knowledge of the attachment ability of the catechol group is derived from the substances secreted on the antennae of marine organisms of shellfish, which may be attached to a variety of different surfaces, because the catechol group is present in the adhesion proteins secreted by the antennae. The compound containing the catechol group can imitate the miraculous adhesion capability of shellfish, so that the polytetrafluoroethylene can be tightly adhered to the surface of the carbon fiber of the gas diffusion layer.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

FIG. 1 is a scanning electron micrograph of gas diffusion layer failure as described in the present specification;

FIG. 2 is a schematic flow chart of a preparation method provided by an embodiment of the invention;

fig. 3 is a schematic structural diagram of a membrane electrode assembly according to an embodiment of the present invention;

fig. 4 is a comparative graph of the test performance results of the gas diffusion layer prepared by using the example of the present invention and the gas diffusion layer single cell prepared by the conventional scheme.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In general, the basic components of a proton exchange membrane fuel cell include: polar plate, gas diffusion layer, catalyst layer and proton exchange membrane.

The electrode plate can be divided into a unipolar plate and a bipolar plate, and has the functions of separating each single cell in the cell stack, conveying fuel and oxygen to the gas diffusion layer through a channel on the electrode plate, and meanwhile, having high conductivity so as to lead current to the outside.

The gas diffusion layer, the catalyst layer and the proton exchange membrane constitute a membrane electrode assembly. The gas diffusion layer, which is one of the key materials in a pem fuel cell, is located between the catalyst layer and the plate and is the outermost layer of the mea, which provides contact between the mea and the plate, distributes the reactants to the catalyst layer, and allows the reaction product water to leave the electrode surface, allowing water to pass between the electrodes and the flow channels.

In view of the above requirements, the materials for gas diffusion layers, which are currently being used in fuel cells, are porous carbon materials, such as carbon papers, e.g., carbon fiber papers, or carbon cloths, e.g., carbon fiber cloths, and are coated with a microporous layer on one side surface thereof. In order to improve the transport of reaction gas and liquid water in the gas diffusion layer, a hydrophobic treatment is generally performed on carbon paper or carbon cloth to construct hydrophobic gas-phase channels.

In a common hydrophobic treatment process, the formulation of the hydrophobic treatment slurry is polytetrafluoroethylene solution (aqueous solution of polytetrafluoroethylene, solid content of polytetrafluoroethylene is 5-65%), ethanol, isopropanol and water. The polytetrafluoroethylene serving as a hydrophobic agent can be attached to the surface of carbon fiber of the gas diffusion layer to form a hydrophobic protective film, meanwhile, the attachment of the polytetrafluoroethylene can also reduce single macropores in the carbon paper or the carbon cloth substrate (for example, about 90% of the pores in Toray H060 carbon paper are macropores with the pore diameter larger than 20 microns, so that a large amount of water is accumulated in the gas diffusion layer to prevent the reaction gas from entering), the pore diameter of the gas diffusion layer substrate is reduced and evenly distributed, a good pore structure and hydrophobicity are provided, the gas and the water are redistributed, and the electrode catalyst layer is prevented from being flooded with water.

However, the surface of the carbon fiber is hydrophilic, and is not easy to combine with a hydrophobic polytetrafluoroethylene solution, and although the conventional slurry preparation method can solve the problem that the gas diffusion layer material is hydrophobic, the polytetrafluoroethylene is not uniformly distributed on the surface of the carbon fiber and is easy to agglomerate. Particularly, in the long-term operation process of the fuel cell stack, especially the operation condition of the fuel cell stack for vehicles is very complex and harsh, and the fuel cell stack has tens of thousands of hours of operation life and tens of thousands of dry-wet cycles and cold-heat shock. When failure analysis of a membrane electrode which is a core component of a fuel cell stack is carried out, a hydrophobic agent polytetrafluoroethylene material in a gas diffusion layer falls off to cause local flooding, reaction gas is prevented from diffusing to the surface of a catalyst to cause mass transfer polarization to cause local reversal, and finally the electrode voltage of the membrane is reduced or the actual effect of perforation is caused.

The slurry selected by the invention is particularly added with an additive containing catechol or a catechol structure compound, particularly dopamine hydrochloride. Aromatic ring functional groups in the substance are units with pi-pi conjugated structures, are similar to carbon-carbon chemical bond structures on the surfaces of carbon fibers subjected to high-temperature graphitization treatment, can be well contacted and dispersed, and meanwhile, an adjacent dihydroxy structure on an aromatic ring can be well contacted with a polytetrafluoroethylene molecular chain and is also well mutually soluble with alcohol solvents in a polytetrafluoroethylene solution. Particularly, dopamine hydrochloride containing a catechol structure has an amino acid structure functional group, and can further increase the bonding between a polytetrafluoroethylene solution and carbon fibers. The functional group with the amino acid structure can be naturally decomposed to produce gas to be discharged when being subjected to high-temperature treatment in the later process, and is a pore-forming agent which can increase the porosity of the gas diffusion layer material. In fact, the knowledge of the attachment ability of the catechol group is derived from the substances secreted on the antennae of marine organisms of shellfish, which may be attached to a variety of different surfaces, because the catechol group is present in the adhesion proteins secreted by the antennae. The compound containing the catechol group can imitate the miraculous adhesion capability of shellfish, so that the polytetrafluoroethylene can be tightly adhered to the surface of the carbon fiber of the gas diffusion layer.

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.

Referring to fig. 1, fig. 1 is a scanning electron microscope photograph showing that a gas diffusion layer material prepared by a gas diffusion layer hydrophobic process method of the present invention fails after being applied to a fuel cell stack, and it is apparent from the photograph that a hydrophobic substance coated on the surface of carbon fibers falls off to expose the carbon fibers.

The preparation method of the present invention is shown in fig. 2, and fig. 2 is a schematic flow chart of a preparation method provided in an embodiment of the present invention, and the preparation method includes:

step S11: preparing hydrophobic treatment slurry, which consists of water, polytetrafluoroethylene solution, isopropanol, ethanol, catechol or a compound containing catechol structure, especially dopamine hydrochloride, and mixing and dispersing uniformly.

Step S12: a gas diffusion layer substrate, such as carbon paper or carbon cloth, is wetted in a hydrophobically treated slurry.

Step S13: and (4) putting the gas diffusion layer soaked with the hydrophobic treatment slurry into a drying box for high-temperature drying treatment.

Step S14: repeating the above steps S12 and S13 2-8 times

The performance of the fuel cell (sample one) using the gas diffusion layer according to the present invention is compared with the performance of the fuel cell (sample two) prepared by the conventional technology, with reference to specific design parameters.

Sample one: the technical scheme of the embodiment of the invention prepares the gas diffusion layer

1) Preparing hydrophobic treatment slurry of a gas diffusion layer:

slurry A: 150ml of 60% polytetrafluoroethylene solution is measured and transferred to a 3000ml volumetric flask, 20ml of isopropanol and 20ml of ethanol are added, 4.5g of dopamine hydrochloride is weighed and transferred to the volumetric flask, the volumetric flask is fixed to 3000ml by deionized water, and the flask is shaken uniformly.

Slurry B: 15ml of 60% polytetrafluoroethylene solution is weighed and transferred to a 3000ml volumetric flask, 0.45g of dopamine hydrochloride is weighed and transferred to the volumetric flask, the volumetric flask is fixed to 3000ml by deionized water, and the flask is shaken uniformly.

2) Dispersing the slurry for hydrophobic treatment of the gas diffusion layer: and transferring the prepared slurry into a glass container, placing the glass container into an ultrasonic cleaning machine, ultrasonically oscillating for 1 hour, and simultaneously keeping the temperature of water in the ultrasonic cleaning machine not higher than 35 ℃.

3) And respectively pouring the slurry A and the slurry B subjected to the ultrasonic dispersion and uniform treatment into two containers with the areas of 500mm x 500 mm.

4) The gas diffusion layer substrate was completely immersed in the slurry a for a period of not less than 10 seconds.

5) And (3) putting the gas diffusion layer soaked with the hydrophobic treatment slurry into an air-blast drying box, wherein the temperature of the air-blast drying box is 245 ℃, and the drying time is 5 minutes.

6) The dried gas diffusion layer is taken out and then the operations of steps 4 and 5 are repeated once.

7) And (6) immersing the gas diffusion layer treated in the step (6) into the slurry B solution, wherein the soaking time is not less than 10 seconds.

8) And (4) placing the gas diffusion layer treated in the step (7) into an air-blowing drying oven, wherein the temperature of the air-blowing drying oven is 245 ℃, and the drying time is 5 minutes.

9) The gas diffusion layer resulting from the treatment of step 8 is loaded and considered to be at the end of the hydrophobic treatment if its weight is increased by 8 +/-0.5% compared to the weight of the gas diffusion layer substrate in step 4. If the weight gain does not reach this range, steps 7 and 8 are repeated until a weight gain of 8 +/-0.5% is reached.

10) Microporous layer slurry preparation: 3.2g of Vulcan XC-72(R), 60ml of aqueous solution containing 2.5g of ammonium oxalate and 8g of 20 percent PTFE diluent are weighed and poured into a certain amount of isopropanol to be uniformly stirred to prepare slurry with the viscosity of 300 cp.

11) And (3) coating the slurry prepared in the step 10 on the gas diffusion layer obtained in the step 9 after the hydrophobic treatment.

12) And (3) putting the gas diffusion layer obtained in the step (11) into a muffle furnace, heating at the heating rate of 5 ℃/min, finally roasting at 340 ℃ for 60min, and taking the gas diffusion layer after the furnace temperature is reduced to room temperature.

The gas diffusion layer material prepared in this example was measured to have a porosity of 53.1% and a thickness of 213 μm according to the following microporous layer porosity test method, and contact angles of both surfaces were 155 ° and 144 °, respectively.

Comparative example sample two: preparation of microporous layer structure by traditional technical scheme

1) Preparing hydrophobic treatment slurry of a gas diffusion layer:

slurry A: 150ml of 60% polytetrafluoroethylene solution is measured and transferred to a 3000ml volumetric flask, the volumetric flask is fixed to 3000ml with deionized water, and the flask is shaken uniformly.

Slurry B: 15ml of 60% polytetrafluoroethylene solution is weighed and transferred to a 3000ml volumetric flask, the volumetric flask is fixed to 3000ml with deionized water, and the flask is shaken uniformly.

2) Dispersing the slurry for hydrophobic treatment of the gas diffusion layer: and transferring the prepared slurry into a glass container, placing the glass container into an ultrasonic cleaning machine, ultrasonically oscillating for 1 hour, and simultaneously keeping the temperature of water in the ultrasonic cleaning machine not higher than 35 ℃.

3) And respectively pouring the slurry A and the slurry B subjected to the ultrasonic dispersion and uniform treatment into two containers with the areas of 500mm x 500 mm.

4) The gas diffusion layer substrate was completely immersed in the slurry a for a period of not less than 10 seconds.

5) And (3) putting the gas diffusion layer soaked with the hydrophobic treatment slurry into an air-blast drying box, wherein the temperature of the air-blast drying box is 245 ℃, and the drying time is 5 minutes.

6) The dried gas diffusion layer is taken out and then the operations of steps 4 and 5 are repeated once.

7) And (6) immersing the gas diffusion layer treated in the step (6) into the slurry B solution, wherein the soaking time is not less than 10 seconds.

8) And (4) placing the gas diffusion layer treated in the step (7) into an air-blowing drying oven, wherein the temperature of the air-blowing drying oven is 245 ℃, and the drying time is 5 minutes.

9) The gas diffusion layer resulting from the treatment of step 8 is loaded and considered to be at the end of the hydrophobic treatment if its weight is increased by 8 +/-0.5% compared to the weight of the gas diffusion layer substrate in step 4. If the weight gain does not reach this range, steps 7 and 8 are repeated until a weight gain of 8 +/-0.5% is reached.

10) Microporous layer slurry preparation: 3.2g of Vulcan XC-72(R), 60ml of aqueous solution containing 2.5g of ammonium oxalate and 8g of 20 percent PTFE diluent are weighed and poured into a certain amount of isopropanol to be uniformly stirred to prepare slurry with the viscosity of 300 cp.

11) And (3) coating the slurry prepared in the step 10 on the gas diffusion layer obtained in the step 9 after the hydrophobic treatment.

12) And (3) putting the gas diffusion layer obtained in the step (11) into a muffle furnace, heating at the heating rate of 5 ℃/min, finally roasting at 340 ℃ for 60min, and taking the gas diffusion layer after the furnace temperature is reduced to room temperature.

The gas diffusion layer material prepared in this example was measured to have a porosity of 49.7% and a thickness of 210 μm according to the following microporous layer porosity test method, and contact angles of both surfaces were 150 ° and 142 °, respectively.

Sample three: the technical scheme of the embodiment of the invention prepares the gas diffusion layer

1) Preparing hydrophobic treatment slurry of a gas diffusion layer:

slurry A: 150ml of 60% polytetrafluoroethylene solution is measured and transferred to a 3000ml volumetric flask, 20ml of isopropanol is added, 20ml of ethanol is added, 9g of catechol is weighed and transferred to the volumetric flask, deionized water is used for fixing the volume of the volumetric flask to 3000ml, and the volumetric flask is shaken uniformly.

Slurry B: 15ml of 60% polytetrafluoroethylene solution is weighed and transferred to a 3000ml volumetric flask, 0.9g of catechol is weighed and transferred to the volumetric flask, the volumetric flask is fixed to 3000ml by deionized water, and the flask is shaken uniformly.

2) Dispersing the slurry for hydrophobic treatment of the gas diffusion layer: and transferring the prepared slurry into a glass container, placing the glass container into an ultrasonic cleaning machine, ultrasonically oscillating for 1 hour, and simultaneously keeping the temperature of water in the ultrasonic cleaning machine not higher than 35 ℃.

3) And respectively pouring the slurry A and the slurry B subjected to the ultrasonic dispersion and uniform treatment into two containers with the areas of 500mm x 500 mm.

4) The gas diffusion layer substrate was completely immersed in the slurry a for a period of not less than 10 seconds.

5) And (3) putting the gas diffusion layer soaked with the hydrophobic treatment slurry into an air-blast drying box, wherein the temperature of the air-blast drying box is 245 ℃, and the drying time is 5 minutes.

6) The dried gas diffusion layer is taken out and then the operations of steps 4 and 5 are repeated once.

7) And (6) immersing the gas diffusion layer treated in the step (6) into the slurry B solution, wherein the soaking time is not less than 10 seconds.

8) And (4) placing the gas diffusion layer treated in the step (7) into an air-blowing drying oven, wherein the temperature of the air-blowing drying oven is 245 ℃, and the drying time is 5 minutes.

9) The gas diffusion layer resulting from the treatment of step 8 is loaded and considered to be at the end of the hydrophobic treatment if its weight is increased by 8 +/-0.5% compared to the weight of the gas diffusion layer substrate in step 4. If the weight gain does not reach this range, steps 7 and 8 are repeated until a weight gain of 8 +/-0.5% is reached.

10) Microporous layer slurry preparation: 3.2g of Vulcan XC-72(R), 60ml of aqueous solution containing 2.5g of ammonium oxalate and 8g of 20 percent PTFE diluent are weighed and poured into a certain amount of isopropanol to be uniformly stirred to prepare slurry with the viscosity of 300 cp.

11) And (3) coating the slurry prepared in the step 10 on the gas diffusion layer obtained in the step 9 after the hydrophobic treatment.

12) And (3) putting the gas diffusion layer obtained in the step (11) into a muffle furnace, heating at the heating rate of 5 ℃/min, finally roasting at 340 ℃ for 60min, and taking the gas diffusion layer after the furnace temperature is reduced to room temperature.

The gas diffusion layer material prepared in this example was measured to have a porosity of 52.4% and a thickness of 215 μm according to the following microporous layer porosity test method, and contact angles of both surfaces were 158 ° and 150 °, respectively.

In the examples of the present invention, the porosity of the microporous layer was measured by a dipping method. Firstly, weighing 1 gas diffusion layer substrate with area a and thickness b1 and subjected to hydrophobic treatment, soaking the gas diffusion layer substrate in decane until the weight is constant (decane is used as wetting liquid), soaking the gas diffusion layer substrate in decane due to low surface energy until the gas diffusion layer substrate can be soaked in all pores of the diffusion layer substrate, and determining the mass 2 of the diffusion layer before and after soaking by using a weighing method. Weighing 3 the prepared diffusion layer (comprising the substrate layer and the microporous layer) with the area of a and the thickness of b2, soaking the diffusion layer (comprising the substrate layer and the microporous layer) in decane until the weight is constant, determining 4 the weight of the diffusion layer (comprising the substrate layer and the microporous layer) before and after soaking by using a weighing method, and calculating the porosity of the microporous layer by the following formula:

FIG. 3 is a diagram showing the components of a fuel cell membrane electrode assembled by gas diffusion layers prepared according to the present invention, where 1 is a proton exchange membrane, 21 is an anode catalyst layer, 31 is an anode gas diffusion layer microporous layer, 41 is an anode gas diffusion layer substrate part, 22 is an anode catalyst layer, 32 is an anode gas diffusion layer microporous layer, and 42 is an anode gas diffusion layer substrate part.

And (3) respectively assembling the first sample and the second sample into a proton exchange membrane fuel cell with an active area of 200cm2, and detecting and comparing electrochemical performances of the cell. The detection environment for the data of fig. 4 is: the cathode inlet pressure was the same as the anode inlet pressure, the anode and anode inlet gas humidity was 50%, and the other operating conditions were the same.

The result shows that the voltage of the battery prepared by the sample I is still stable above the density of 1.0A/cm2, while the voltage of the battery prepared by the sample II is obviously reduced, and the phenomenon of mass transfer polarization occurs. In fig. 4, the horizontal axis represents current density, and the vertical axis represents voltage. Therefore, the fuel cell prepared by the technical scheme has better cell performance.

In some embodiments, the microporous layer slurry used in step S11 includes a conductive material, a pore former, a hydrophobic agent, and a dispersion liquid, and is uniformly mixed and dispersed.

The process conditions may be adjusted as necessary to form gas diffusion layers of different thicknesses, for example, to obtain a thickness of the gas diffusion layer of between 10 μm and 500 μm.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

The invention may be implemented by the following examples:

1. a gas diffusion layer for a fuel cell, comprising a gas diffusion layer substrate, and a water repellent treatment slurry coated on the surface of the gas diffusion layer; wherein the additive containing catechol or catechol structure compound is added into the hydrophobic treatment slurry.

2. The gas diffusion layer according to example 1, wherein dopamine hydrochloride is added to the hydrophobic treatment slurry.

3. The gas diffusion layer according to example 1, wherein the hydrophobic treatment slurry is composed of water, a polytetrafluoroethylene solution, isopropyl alcohol, ethanol, catechol, or a compound containing a catechol structure.

4. The gas diffusion layer according to example 3, wherein the compound having a catechol structure is dopamine hydrochloride.

5. The gas diffusion layer according to example 1, wherein the hydrophobic treatment slurry comprises water, a polytetrafluoroethylene solution, isopropyl alcohol, ethanol, catechol, or a compound containing a catechol structure.

6. The gas diffusion layer according to example 5, wherein the compound having a catechol structure is dopamine hydrochloride.

7. The gas diffusion layer according to example 1, wherein the catechol or the additive containing a catechol structural compound is used in an amount of 0.05% to 30% by mass based on the total mass of the slurry.

8. The gas diffusion layer structure according to example 1, wherein the thickness of the gas diffusion layer is 10 μm to 500 μm.

9. A production method for producing a gas diffusion layer according to any one of examples 1 to 8, comprising:

the preparation method of the hydrophobic treatment slurry comprises the following steps: mixing slurry comprising water, polytetrafluoroethylene solution, isopropanol, ethanol, catechol or catechol-containing compound in proportion, dispersing and mixing with a homogenizer, and further dispersing with an ultrasonic cleaner;

immersing the gas diffusion layer substrate in the slurry;

taking the gas diffusion layer base material out of the slurry, and heating and drying the gas diffusion layer base material;

repeating the steps for 2-8 times in the preparation process of the gas diffusion layer; and

and (4) coating the microporous layer on the gas diffusion layer substrate subjected to the hydrophobic treatment.

10. The method according to example 9, wherein the compound having a catechol structure is dopamine hydrochloride.

11. The method according to example 9, wherein the catechol or the additive containing a catechol structural compound is used in an amount of 0.05 to 30% by mass based on the total mass of the slurry.

12. The method according to example 9, wherein the slurry is taken out and then dried by heating at a temperature of 200 to 300 ℃, and the drying under normal pressure or vacuum may be selected.

13. The production method according to example 9, characterized in that the thickness of the gas diffusion layer is 10 μm to 500 μm.

14. A membrane electrode assembly, comprising: a cathode-side gas diffusion layer, a cathode-side catalyst layer, a proton exchange membrane, an anode-side catalyst layer, and an anode-side gas diffusion layer which are stacked in this order; wherein the cathode-side gas diffusion layer comprises the gas diffusion layer according to any one of examples 1 to 8; the anode-side gas diffusion layer includes the gas diffusion layer according to any one of examples 1 to 8.

15. A fuel cell, characterized in that the fuel cell comprises: a fuel cell stack comprising the membrane electrode assembly, the electrode plate, the current collecting plate, the insulating plate, the sealing structure, and the end plate according to example 14.