Fuel cell, gas diffusion layer and preparation method thereof

Abstract

The invention discloses a fuel cell and a gas diffusion layer thereof, the gas diffusion layer is suitable for forming the fuel cell, and the pore volume value range of the gas diffusion layer is 2.3 ml / g to 3.5 ml / g; and the value range of the pore volume ratio of the micropores with the pore diameters in the range of 10-60 microns in the gas diffusion layer is 55-70%. The fuel cell and the gas diffusion layer thereof have the beneficial effects that the fuel cell and the gas diffusion layer thereof can obtain better cell performance by controlling the proportion of the micropores in the preset aperture range.

Description

Technical Field

[0001] The present application belongs to the field of fuel cell technology, and in particular, relates to a fuel cell, a gas diffusion layer and a preparation method thereof. Background Art

[0002] A fuel cell (also known as a proton exchange membrane cell) is composed of a plate, a gas expansion layer, a catalyst layer, a proton exchange membrane, etc.

[0003] Among them, the gas diffusion layer plays the role of water vapor transport, electron conduction, heat transfer, etc.

[0004] Generally speaking, the gas diffusion layer usually includes a carbon paper layer and a microporous layer; wherein, the carbon paper layer is formed by impregnation, graphitization, hydrophobization and other processes of carbon fiber, and the micropore size of the carbon paper layer is relatively large, distributed between 10μm and 100μm; the microporous layer is formed by mixing carbon black, hydrophobic agent and other additives to form a slurry, coating it on carbon paper and then subjecting it to heat treatment; the micropore size of the microporous layer is relatively small, distributed between 1μm and 20μm.

[0005] The water in the fuel cell is mainly composed of two parts. One is the anode and cathode gases that are humidified externally and flow into the battery through the bipolar plate flow channel. The other part is generated by the reduction reaction of the cathode catalyst layer.

[0006] The microporous layer plays a role in gradient dispersion of water vapor, "atomizing" the water introduced from the carbon paper side and discharging the water produced by the catalyst layer in time. However, under high-power density operating conditions, fuel cells often suffer from insufficient "three-transmission" capabilities of the gas diffusion layer, resulting in the appearance of a "liquid film" between the gas diffusion layers, leading to performance degradation and life attenuation. The reason lies in the insufficient design of the pore structure on the gas diffusion layer. When the pore size distribution concentration of the gas diffusion layer is low, water vapor will face differences in resistance when penetrating different pore sizes, and has a radial flow tendency; the matching of large pores and small pores is poor, resulting in a rapid increase in water saturated vapor pressure or obstruction of gas transmission at the MPL-carbon paper coating interface. Summary of the invention

[0007] In view of this, the present application provides a method for solving the aforementioned technical problems.

[0008] In a first aspect, an embodiment of the present application provides a gas diffusion layer suitable for constituting a fuel cell, wherein the pore volume of the gas diffusion layer ranges from 2.3 ml / g to 3.5 ml / g;

[0009] The pore volume ratio of micropores with a pore diameter ranging from 10 μm to 60 μm in the gas diffusion layer ranges from 55% to 70%.

[0010] Optionally, in some embodiments of the present application, the gas diffusion layer includes a carbon paper layer and a microporous layer;

[0011] The carbon black particle size in the gas diffusion layer ranges from 10 μm to 30 μm;

[0012] and / or, the surface oxygen content of the gas diffusion layer ranges from 0.6wt% to 1.2wt%;

[0013] And / or, the coating thickness of the microporous layer of the gas diffusion layer ranges from 20 μm to 50 μm;

[0014] And / or, the hydrophobic agent content of the gas diffusion layer ranges from 5wt% to 30wt%;

[0015] And / or, the thickness of the carbon paper layer ranges from 140 μm to 180 μm;

[0016] And / or, the porosity of the carbon paper layer ranges from 75% to 85%.

[0017] Optionally, in some embodiments of the present application, the pore distribution span of the gas diffusion layer ranges from 0.6 to 0.8;

[0018] W w =(W 20 -W 30 )÷(W 10 -W 60 )

[0019] The pore distribution span W of the gas diffusion layer w The calculation is performed using the following formula:

[0020] Among them, the W 10 is the cumulative pore volume fraction corresponding to a pore size of 10 μm when the pore volume is tested by mercury intrusion;

[0021] The W 20 is the cumulative pore volume fraction corresponding to a pore diameter of 20 μm when the pore volume is tested by mercury intrusion porosimetry;

[0022] The W 30 is the cumulative pore volume fraction corresponding to a pore diameter of 30 μm when the pore volume is tested by mercury intrusion;

[0023] The W 60 It is the cumulative pore volume fraction corresponding to a pore size of 60 μm when the pore volume is tested by mercury intrusion porosimetry.

[0024] Optionally, in some embodiments of the present application, wherein W 10 is the cumulative pore volume fraction corresponding to a pore size of 10 μm when the pore volume is tested by mercury intrusion, and its value range is 78% to 85%;

[0025] and / or, W 20 is the cumulative pore volume fraction corresponding to a pore diameter of 20 μm when the pore volume is tested by mercury intrusion, and its value range is 75% to 65%;

[0026] and / or, W 30 is the cumulative pore volume fraction corresponding to a pore size of 30 μm when the pore volume is tested by mercury intrusion, and its value range is 25% to 33%;

[0027] and / or, W 60 It is the cumulative pore volume fraction corresponding to a pore diameter of 60 μm when the pore volume is tested by mercury intrusion, and its value range is 10% to 15%.

[0028] In a second aspect, an embodiment of the present application provides a method for preparing a gas diffusion layer, comprising:

[0029] applying a conductive slurry to carbon paper to form a gas diffusion layer blank;

[0030] Drying and heating the gas diffusion layer blank to obtain the gas diffusion layer;

[0031] The pore volume of the gas diffusion layer ranges from 2.3 ml / g to 3.5 ml / g; the pore volume ratio of micropores with a pore size ranging from 10 μm to 60 μm in the gas diffusion layer ranges from 55% to 70%.

[0032] Optionally, in some embodiments of the present application, the gas diffusion layer includes a carbon paper layer and a microporous layer;

[0033] The carbon black particle size in the gas diffusion layer ranges from 10 μm to 30 μm;

[0034] and / or, the surface oxygen content of the gas diffusion layer ranges from 0.6wt% to 1.2wt%;

[0035] And / or, the coating thickness of the microporous layer of the gas diffusion layer ranges from 20 μm to 50 μm;

[0036] And / or, the hydrophobic agent content of the gas diffusion layer ranges from 5wt% to 30wt%;

[0037] And / or, the thickness of the carbon paper layer ranges from 140 μm to 180 μm;

[0038] And / or, the porosity of the carbon paper layer ranges from 75% to 85%.

[0039] Optionally, in some embodiments of the present application, the pore distribution span of the gas diffusion layer ranges from 0.6 to 0.8;

[0040] W w =(W 20 -W 30 )÷(W 10 -W 60 )

[0041] The pore distribution span W of the gas diffusion layer w The calculation is performed using the following formula:

[0042] Among them, the W 10 is the cumulative pore volume fraction corresponding to a pore size of 10 μm when the pore volume is tested by mercury intrusion;

[0043] The W 20 is the cumulative pore volume fraction corresponding to a pore diameter of 20 μm when the pore volume is tested by mercury intrusion porosimetry;

[0044] The W 30 is the cumulative pore volume fraction corresponding to a pore diameter of 30 μm when the pore volume is tested by mercury intrusion;

[0045] The W 60 is the cumulative pore volume fraction corresponding to a pore size of 60 μm when the pore volume is tested by mercury intrusion;

[0046] and / or, the W 10 is the cumulative pore volume fraction corresponding to a pore size of 10 μm when the pore volume is tested by mercury intrusion, and its value range is 78% to 85%;

[0047] and / or, the W 20 is the cumulative pore volume fraction corresponding to a pore diameter of 20 μm when the pore volume is tested by mercury intrusion, and the value range is 75% to 65%;

[0048] and / or, the W 30 is the cumulative pore volume fraction corresponding to a pore size of 30 μm when the pore volume is tested by mercury intrusion, and its value range is 25% to 33%;

[0049] and / or, the W 60 It is the cumulative pore volume fraction corresponding to a pore diameter of 60 μm when the pore volume is tested by mercury intrusion, and its value range is 10% to 15%.

[0050] Optionally, in some embodiments of the present application, the conductive paste includes: carbon black, a solvent, and a hydrophobic agent;

[0051] Wherein, the mass percentage of the carbon black in the conductive paste ranges from 4% to 10%; and / or

[0052] And / or, the particle size of the carbon black ranges from 8 μm to 50 μm;

[0053] And / or, the hydrophobic agent includes: one or more of polytetrafluoroethylene and silicone resin;

[0054] And / or, the mass percentage of the hydrophobic agent in the conductive paste is in the range of 15% to 35%;

[0055] And / or, the solvent includes: one or more of water, propanol, ethanol, isopropanol, butanol;

[0056] And / or, the mass percentage of the solvent in the conductive paste is in a range of 75% to 85%;

[0057] And / or, the conductive paste further comprises: one or more of a dispersant, a stabilizer, a thickener, an antistatic agent, a paste penetrant, a softener, and a surfactant.

[0058] And / or, the surfactant includes: one or more of imidazoline, polyoxyethylene ether, sodium alkyl sulfonate, betaine, amino acid, polyacrylate, polyethylene glycol, polyvinyl pyrrolidone, polyvinyl alcohol, cerium nitrate, and cerous nitrate;

[0059] And / or, the mass percentage of the surfactant in the conductive paste is in a range of 3% to 19%;

[0060] And / or, the preparation method further comprises: performing a hydrophobic treatment on the carbon paper, wherein the mass concentration of the hydrophobic agent in the hydrophobic treatment ranges from 5% to 15%;

[0061] And / or, the number of times of the hydrophobic treatment ranges from 1 to 5.

[0062] Optionally, in some embodiments of the present application, the drying equipment used to dry and heat the gas diffusion layer includes one or more of a blast oven, a vacuum oven, a microwave evaporator, and a nitrogen-filled oven; and / or

[0063] and / or, the drying temperature when drying and heating the gas diffusion layer is in the range of 30° C. to 120° C.;

[0064] and / or, the drying wind speed during the drying and heating of the gas diffusion layer is in the range of 0.1 m / s to 1.0 m / s;

[0065] and / or, the absolute pressure value of the gas diffusion layer during drying and heating is in the range of 1 KPa to 201 KPa;

[0066] And / or, the drying time when the gas diffusion layer is dried and heated is in the range of 5 min to 60 min;

[0067] and / or, the drying atmosphere during the drying and heating treatment of the gas diffusion layer comprises one or more of nitrogen, nitrogen-oxygen mixed gas, oxygen, and CO2;

[0068] and / or, the heating equipment used for drying and heating the gas diffusion layer includes: one or more of a microwave muffle furnace, a tubular furnace, a high temperature muffle furnace, and a resistance muffle furnace;

[0069] and / or, the heating temperature when drying and heating the gas diffusion layer is in the range of 250° C. to 350° C.;

[0070] and / or, the drying time when the gas diffusion layer is dried and heated is in the range of 60 min to 300 min;

[0071] And / or, the drying atmosphere during the drying and heating treatment of the gas diffusion layer includes nitrogen, nitrogen-oxygen mixed gas, oxygen, CO 2 One or more of .

[0072] In a third aspect, an embodiment of the present application provides a fuel cell, comprising the aforementioned gas diffusion layer or a gas diffusion layer prepared by the aforementioned preparation method.

[0073] The beneficial effects of the present application are as follows: a fuel cell and a gas diffusion layer thereof are provided, which can achieve better battery performance by controlling the proportion of micropores within a preset pore size range. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0075] Figure 1 is a schematic structural diagram of a gas diffusion layer provided in some embodiments of the present application;

[0076] Figure 2 It is a schematic diagram of the main steps of the preparation method provided in some embodiments of the present application;

[0077] Figure 3 It is a physical schematic diagram of a gas diffusion layer provided in some embodiments of the present application. DETAILED DESCRIPTION

[0078] The technical solutions 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 only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application. In addition, it should be understood that the specific implementation methods described herein are only used to illustrate and explain the present application, and are not used to limit the present application.

[0079] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0080] In this application, unless otherwise stated, directional words such as "upper" and "lower" generally refer to the upper and lower parts of the device in actual use or working state, specifically the drawing direction in the accompanying drawings; while "inner" and "outer" refer to the outline of the device. In addition, in the description of this application, the term "including" means "including but not limited to". The terms first, second, third, etc. are used only as labels and do not impose numerical requirements or establish an order.

[0081] In this application, "and / or" describes the association relationship of associated objects, indicating that there may be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural.

[0082] In the present application, "at least one" means one or more, and "plurality" means two or more. "One or more", "at least one of the following" or similar expressions refer to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b, or c", or "at least one of a, b, and c" can all mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, c can be single or multiple, respectively.

[0083] 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.

[0084] The fuel cell of the present application includes: a polar plate, a gas diffusion layer, a catalyst layer, and a proton exchange membrane. The fuel cell is a "sandwich" structure, with a proton exchange membrane in the middle, and catalysts, gas diffusion layers, and bipolar plates distributed on both sides in sequence, wherein the proton exchange membrane plays a role in hydrogen mass transfer, the catalyst oxidizes and reduces hydrogen and oxygen, the gas diffusion layer plays a role in water vapor dispersion and transmission, the surface of the bipolar plate has a flow field gas conduction, and its mechanical strength supports the entire membrane electrode structure. This part is conventional technology in the field and will not be elaborated here.

[0085] Reference Figure 1 As shown, the gas diffusion layer of the present application includes: a carbon paper layer and a microporous layer.

[0086] The pore volume of the gas diffusion layer ranges from 2.3 ml / g to 3.5 ml / g; the pore volume ratio of micropores with a pore size ranging from 10 μm to 60 μm in the gas diffusion layer ranges from 55% to 70%.

[0087] In some embodiments of the present application, the gas diffusion layer includes a carbon paper layer and a microporous layer; the particle size of the carbon black in the gas diffusion layer ranges from 10 μm to 30 μm.

[0088] In some embodiments of the present application, the surface oxygen content of the gas diffusion layer ranges from 0.6 wt % to 1.2 wt %.

[0089] In some embodiments of the present application, the coating thickness of the microporous layer of the gas diffusion layer ranges from 20 μm to 50 μm.

[0090] In some embodiments of the present application, the hydrophobic agent content of the gas diffusion layer ranges from 5 wt % to 30 wt %.

[0091] In some embodiments of the present application, the thickness of the carbon paper layer ranges from 140 μm to 180 μm.

[0092] In some embodiments of the present application, the porosity of the carbon paper layer ranges from 75% to 85%.

[0093] In some embodiments of the present application, the pore distribution span of the gas diffusion layer ranges from 0.6 to 0.8.

[0094] W w =(W 20 -W 30 )÷(W 10 -W 60 )

[0095] The pore distribution span W of the gas diffusion layer w The calculation is performed using the following formula:

[0096] Among them, the W 10 is the cumulative pore volume fraction corresponding to a pore size of 10 μm when the pore volume is tested by mercury intrusion;

[0097] The W 20 is the cumulative pore volume fraction corresponding to a pore diameter of 20 μm when the pore volume is tested by mercury intrusion porosimetry;

[0098] The W 30 is the cumulative pore volume fraction corresponding to a pore diameter of 30 μm when the pore volume is tested by mercury intrusion;

[0099] The W 60 It is the cumulative pore volume fraction corresponding to a pore size of 60 μm when the pore volume is tested by mercury intrusion porosimetry.

[0100] In some embodiments of the present application, wherein W 10 It is the cumulative pore volume fraction corresponding to a pore diameter of 10 μm when the pore volume is tested by mercury intrusion, and its value range is 78% to 85%.

[0101] In some embodiments of the present application, W 20 It is the cumulative pore volume fraction corresponding to a pore diameter of 20 μm when the pore volume is tested by mercury intrusion, and its value range is 75% to 65%.

[0102] In some embodiments of the present application, W 30 It is the cumulative pore volume fraction corresponding to a pore diameter of 30 μm when the pore volume is tested by mercury intrusion, and its value range is 25% to 33%.

[0103] In some embodiments of the present application, W 60 It is the cumulative pore volume fraction corresponding to a pore diameter of 60 μm when the pore volume is tested by mercury intrusion, and its value range is 10% to 15%.

[0104] Reference Figure 2As shown, the embodiment of the present application provides a method for preparing a gas diffusion layer, comprising:

[0105] S100: applying a conductive slurry to carbon paper to form a gas diffusion layer blank;

[0106] S200: drying and heating the gas diffusion layer blank to obtain the gas diffusion layer;

[0107] The pore volume of the gas diffusion layer ranges from 2.3 ml / g to 3.5 ml / g; the pore volume ratio of micropores with a pore size ranging from 10 μm to 60 μm in the gas diffusion layer ranges from 55% to 70%.

[0108] In some embodiments of the present application, the conductive paste includes: carbon black, a solvent, and a hydrophobic agent;

[0109] Wherein, the mass percentage of the carbon black in the conductive paste ranges from 4% to 10%; in some embodiments of the present application

[0110] In some embodiments of the present application, the particle size of the carbon black ranges from 8 μm to 50 μm;

[0111] In some embodiments of the present application, the hydrophobic agent includes: one or more of polytetrafluoroethylene and silicone resin;

[0112] In some embodiments of the present application, the mass percentage of the hydrophobic agent in the conductive paste ranges from 15% to 35%;

[0113] In some embodiments of the present application, the solvent includes: one or more of water, propanol, ethanol, isopropanol, and butanol;

[0114] In some embodiments of the present application, the mass percentage of the solvent in the conductive paste ranges from 75% to 85%;

[0115] In some embodiments of the present application, the surfactant includes: one or more of imidazoline, polyoxyethylene ether, sodium alkyl sulfonate, betaine, amino acid, polyacrylate, polyethylene glycol, polyvinyl pyrrolidone, polyvinyl alcohol, cerium nitrate, and cerous nitrate;

[0116] In some embodiments of the present application, the mass percentage of the surfactant in the conductive paste ranges from 3% to 19%;

[0117] In some embodiments of the present application, the preparation method further comprises: performing a hydrophobic treatment on the carbon paper, wherein the mass concentration of the hydrophobic agent in the hydrophobic treatment ranges from 5% to 15%;

[0118] In some embodiments of the present application, the number of times of the hydrophobic treatment ranges from 1 to 5;

[0119] In some embodiments of the present application, the conductive paste further includes: one or more of a dispersant, a stabilizer, a thickener, an antistatic agent, a paste penetrant, and a softener.

[0120] In some embodiments of the present application, the drying equipment used for drying and heating the gas diffusion layer includes one or more of a blast oven, a vacuum oven, a microwave evaporator, and a nitrogen-filled oven; in some embodiments of the present application,

[0121] In some embodiments of the present application, the drying temperature when the gas diffusion layer is dried and heated is in the range of 30° C. to 120° C.;

[0122] In some embodiments of the present application, the drying wind speed when the gas diffusion layer is dried and heated is in the range of 0.1 m / s to 1.0 m / s;

[0123] In some embodiments of the present application, the absolute pressure value when the gas diffusion layer is dried and heated ranges from 1 KPa to 201 KPa;

[0124] In some embodiments of the present application, the drying time when the gas diffusion layer is dried and heated is in the range of 5 min to 60 min;

[0125] In some embodiments of the present application, the drying atmosphere when the gas diffusion layer is dried and heated includes one or more of nitrogen, nitrogen-oxygen mixed gas, oxygen, and CO2;

[0126] In some embodiments of the present application, the heating equipment used when drying and heating the gas diffusion layer includes: one or more of a microwave muffle furnace, a tubular furnace, a high temperature muffle furnace, and a resistance muffle furnace;

[0127] In some embodiments of the present application, the heating temperature when drying and heating the gas diffusion layer is in the range of 250° C. to 350° C.;

[0128] In some embodiments of the present application, the drying time when the gas diffusion layer is dried and heated is in the range of 60 min to 300 min;

[0129] In some embodiments of the present application, the drying atmosphere for drying and heating the gas diffusion layer includes nitrogen, nitrogen-oxygen mixed gas, oxygen, CO 2One or more of .

[0130] An embodiment of the present application provides a fuel cell, comprising the aforementioned gas diffusion layer or the gas diffusion layer prepared by the aforementioned preparation method.

[0131] The technical solution of the present application is further illustrated with reference to the following embodiments and comparative examples.

[0132] Example 1

[0133] D 50 Carbon black with a particle size of 10 μm and an oxygen content of 0.8% is added to a 20 wt % PTFE aqueous solution to prepare a conductive slurry; wherein PTFE is the solute of the hydrophobic agent, and the ratio of PTFE to carbon black is 1:5.

[0134] A carbon paper with a thickness of 140 μm was immersed in a solution (hydrophobic agent in hydrophobizing carbon paper) with a mass ratio of PTFE to water of 1:11 for three times.

[0135] The wet carbon paper was then dried in air at 60 °C and placed in a muffle furnace for heat treatment at 300 °C for 2 h to complete the hydrophobicization.

[0136] The hydrophobized carbon paper was fixed on a doctor blade coater, and the slurry was coated on the carbon paper with a roller, with a coating thickness of 20 μm.

[0137] The wet gas diffusion layer was dried in air at 30° C. for 1 h, and then the device was transferred to a muffle furnace and heat treated at 350° C. for 1 h to obtain a gas diffusion layer A1.

[0138] Example 2

[0139] The difference from Example 1 is that the carbon black particle size is D 50 The other process schemes remain unchanged to obtain the gas diffusion layer A2.

[0140] Example 3

[0141] The difference from Example 1 is that the carbon black particle size is D 50 The other process schemes remain unchanged to obtain the gas diffusion layer A3.

[0142] Example 4

[0143] The difference from Example 1 is that the carbon black particle size is D 50 The other process schemes remain unchanged to obtain the gas diffusion layer A3.

[0144] Example 5

[0145] The difference from Example 1 is that the carbon black particle size is D 50The other process schemes remain unchanged to obtain the gas diffusion layer A3.

[0146] Example 6

[0147] The difference from Example 1 is that the carbon black particle size is D 50 The other process schemes remain unchanged to obtain the gas diffusion layer A3.

[0148] Example 7

[0149] The difference from Example 1 is that the carbon black particle size is D 50 The other process schemes remain unchanged to obtain the gas diffusion layer A3.

[0150] Example 8

[0151] The difference from Example 1 is that the thickness of the carbon paper is 160 μm. The other process schemes remain unchanged to obtain a gas diffusion layer A4.

[0152] Example 9

[0153] The difference from Example 1 is that the thickness of the carbon paper is 180 μm. The other process schemes remain unchanged to obtain a gas diffusion layer A5.

[0154] Example 10

[0155] The difference from Example 1 is that the slurry coating thickness is 30 μm. The other process schemes remain unchanged to obtain a gas diffusion layer A6.

[0156] Embodiment 11

[0157] The difference from Example 1 is that the slurry coating thickness is 50 μm. The other process schemes remain unchanged to obtain a gas diffusion layer A7.

[0158] Example 12

[0159] The difference from Example 1 is that the content of the hydrophobic agent is 30%. The other process schemes remain unchanged to obtain a gas diffusion layer A8.

[0160] Example 13

[0161] The difference from Example 1 is that the content of the hydrophobic agent is 40%. The other process schemes remain unchanged to obtain a gas diffusion layer A9.

[0162] 1. Fuel cell preparation method:

[0163] Place a three-snake bipolar plate on the table, and put the PTFE sealing gasket, gas diffusion layer, three-in-one membrane electrode, gas diffusion layer, PTFE sealing gasket, three-snake bipolar plate and other components in sequence, tighten the short plate with a torque of 6N / m, and control the compression rate of the gas diffusion layer to 25%.

[0164] Preparation of three-in-one membrane electrode: The anode catalyst layer is prepared using the commercial catalyst TEC10V30E with a loading of 0.1 mg / cm2; the cathode catalyst layer is prepared using the highly active commercial catalyst TEC10E50E with a high specific surface carbon carrier with a loading of 0.3 mg / cm2; the anode and cathode catalyst layers are placed on both sides of the 8μm proton exchange membrane respectively and placed in a hot press for transfer.

[0165] The gas diffusion layer used was the gas diffusion layer prepared in the above-mentioned embodiment and comparative example.

[0166] 2. Fuel cell testing method:

[0167] The battery performance is tested using a hydrogen fuel cell bench (manufacturer: Qun Yi, equipment model: 850E).

[0168] Activation conditions: Before all tests begin, the single cell needs to be fully activated. The activation conditions are: hydrogen is passed through the anode and air is passed through the cathode. The gas flow rates are 1.5slpm and 2.0slpm respectively. The load is connected to control the voltage to 0.5V for 24h. The battery temperature is 80℃, and the humidity of the anode and cathode is 100RH.

[0169] Test conditions: Polarization curve test was conducted under the conditions of battery temperature of 80℃, anode and cathode humidity of 100RH, back pressure of 150Kpa, and hydrogen to air ratio of 1.5:2.5. The current control mode was adopted, the current started from 0A, and a voltage value was recorded every 2.5A, and each current was stabilized for 5 minutes. Finally, the voltage at the current density value of 3A / cm2 was taken as the battery performance in Table 1.

[0170] The test results are shown in Table 1. The test results of each embodiment and comparative example are as described in Table 1.

[0171] In the present application, by optimizing the preparation process of the microporous layer and the carbon paper layer, a more suitable pore volume and a certain proportion of micropores with a moderate pore size are obtained, which is beneficial to maintain the water balance inside the battery and prevent flooding, thereby protecting the performance and life of the battery.

[0172] The higher the consistency of the size of the mass transfer channel formed by the micropores in the gas diffusion layer, the better the uniformity of the gas diffusion layer. When water vapor flows in the gas diffusion layer, the penetration resistance faced by water vapor at various positions on the gas diffusion layer is consistent, which is conducive to reducing the condensation of water vapor on the plane of the gas diffusion layer and accelerating the discharge of water vapor.

[0173] Table 1

[0174]

[0175]

[0176] In order to actually describe the uniformity of the micropores in the gas diffusion layer, we introduce the concept of describing the pore size distribution span. Referring to Table 1, it can be seen that in Examples 1 to 7, the final pore size distribution span is changed by changing the carbon black particle size. From the performance of this group of batteries, it can be seen that as the pore size distribution span increases, the battery performance is first improved, and then the performance decreases when it reaches the inflection point (Example 6). It can be seen that the pore size distribution span needs to be selected within a certain range to obtain better battery performance.

[0177] The technical solutions provided by the embodiments of the present application are introduced in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea. At the same time, for technical personnel in this field, according to the idea of ​​the present application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A gas diffusion layer suitable for constituting a fuel cell, characterized in that: The pore volume of the gas diffusion layer ranges from 2.3 ml / g to 3.5 ml / g; The pore volume ratio of micropores with a pore diameter ranging from 10 μm to 60 μm in the gas diffusion layer ranges from 55% to 70%.

2. The gas diffusion layer according to claim 1, characterized in that: in, The gas diffusion layer comprises a carbon paper layer and a microporous layer; The carbon black particle size in the gas diffusion layer ranges from 10 μm to 30 μm; and / or, the surface oxygen content of the gas diffusion layer is in the range of 0.6wt% to 1.2wt%; And / or, the coating thickness of the microporous layer of the gas diffusion layer ranges from 20 μm to 50 μm; And / or, the hydrophobic agent content of the gas diffusion layer ranges from 5wt% to 30wt%; And / or, the thickness of the carbon paper layer ranges from 140 μm to 180 μm; And / or, the porosity of the carbon paper layer ranges from 75% to 85%.

3. The gas diffusion layer according to claim 1, characterized in that: in, The pore distribution span of the gas diffusion layer ranges from 0.6 to 0.8; The pore distribution span W of the gas diffusion layer w The calculation is performed using the following formula: IN w =(In 20 -IN 30 )÷(In 10 -IN 60 ) Among them, the W 10 is the cumulative pore volume fraction corresponding to a pore size of 10 μm when the pore volume is tested by mercury intrusion; The W 20 is the cumulative pore volume fraction corresponding to a pore diameter of 20 μm when the pore volume is tested by mercury intrusion porosimetry; The W 30 is the cumulative pore volume fraction corresponding to a pore diameter of 30 μm when the pore volume is tested by mercury intrusion; The W 60 It is the cumulative pore volume fraction corresponding to a pore size of 60 μm when the pore volume is tested by mercury intrusion porosimetry.

4. The gas diffusion layer according to claim 1, characterized in that: in, W 10 is the cumulative pore volume fraction corresponding to a pore size of 10 μm when the pore volume is tested by mercury intrusion, and its value range is 78% to 85%; and / or, W 20 is the cumulative pore volume fraction corresponding to a pore diameter of 20 μm when the pore volume is tested by mercury intrusion, and its value range is 75% to 65%; and / or, W 30 is the cumulative pore volume fraction corresponding to a pore size of 30 μm when the pore volume is tested by mercury intrusion, and its value range is 25% to 33%; and / or, W 60 It is the cumulative pore volume fraction corresponding to a pore diameter of 60 μm when the pore volume is tested by mercury intrusion, and its value range is 10% to 15%.

5. A method for preparing a gas diffusion layer, characterized in that: The preparation method comprises: applying a conductive slurry to carbon paper to form a gas diffusion layer blank; Drying and heating the gas diffusion layer blank to obtain the gas diffusion layer; The pore volume of the gas diffusion layer ranges from 2.3 ml / g to 3.5 ml / g; the pore volume ratio of micropores with a pore size ranging from 10 μm to 60 μm in the gas diffusion layer ranges from 55% to 70%.

6. The preparation method according to claim 5, characterized in that: in, The gas diffusion layer comprises a carbon paper layer and a microporous layer; The carbon black particle size in the gas diffusion layer ranges from 10 μm to 30 μm; and / or, the surface oxygen content of the gas diffusion layer ranges from 0.6wt% to 1.2wt%; And / or, the coating thickness of the microporous layer of the gas diffusion layer ranges from 20 μm to 50 μm; And / or, the hydrophobic agent content of the gas diffusion layer ranges from 5wt% to 30wt%; And / or, the thickness of the carbon paper layer ranges from 140 μm to 180 μm; And / or, the porosity of the carbon paper layer ranges from 75% to 85%.

7. The preparation method according to claim 5 or 6, characterized in that: in, The pore distribution span of the gas diffusion layer ranges from 0.6 to 0.8; The pore distribution span W of the gas diffusion layer w The calculation is performed using the following formula: IN w =(In 20 -IN 30 )÷(In 10 -IN 60 ) Among them, the W 10 is the cumulative pore volume fraction corresponding to a pore size of 10 μm when the pore volume is tested by mercury intrusion; The W 20 is the cumulative pore volume fraction corresponding to a pore diameter of 20 μm when the pore volume is tested by mercury intrusion porosimetry; The W 30 is the cumulative pore volume fraction corresponding to a pore diameter of 30 μm when the pore volume is tested by mercury intrusion; The W 60 is the cumulative pore volume fraction corresponding to a pore size of 60 μm when the pore volume is tested by mercury intrusion; and / or, the W 10 is the cumulative pore volume fraction corresponding to a pore size of 10 μm when the pore volume is tested by mercury intrusion, and its value range is 78% to 85%; and / or, the W 20 is the cumulative pore volume fraction corresponding to a pore diameter of 20 μm when the pore volume is tested by mercury intrusion, and the value range is 75% to 65%; and / or, the W 30 is the cumulative pore volume fraction corresponding to a pore size of 30 μm when the pore volume is tested by mercury intrusion, and its value range is 25% to 33%; and / or, the W 60 It is the cumulative pore volume fraction corresponding to a pore diameter of 60 μm when the pore volume is tested by mercury intrusion, and its value range is 10% to 15%.

8. The preparation method according to claim 5 or 6, Features: in, The conductive paste comprises: carbon black, solvent, and hydrophobic agent; Wherein, the mass percentage of the carbon black in the conductive paste ranges from 4% to 10%; and / or And / or, the particle size of the carbon black ranges from 8 μm to 50 μm; And / or, the hydrophobic agent includes: one or more of polytetrafluoroethylene and silicone resin; And / or, the mass percentage of the hydrophobic agent in the conductive paste is in the range of 15% to 35%; And / or, the solvent includes: one or more of water, propanol, ethanol, isopropanol, butanol; And / or, the mass percentage of the solvent in the conductive paste is in a range of 75% to 85%; And / or, the surfactant includes: one or more of imidazoline, polyoxyethylene ether, sodium alkyl sulfonate, betaine, amino acid, polyacrylate, polyethylene glycol, polyvinyl pyrrolidone, polyvinyl alcohol, cerium nitrate, and cerous nitrate; And / or, the conductive paste further comprises: one or more of a dispersant, a stabilizer, a thickener, an antistatic agent, a paste penetrant, a softener, and a surfactant; And / or, the mass percentage of the surfactant in the conductive paste is in a range of 3% to 19%; And / or, the preparation method further comprises: performing a hydrophobic treatment on the carbon paper, wherein the mass concentration of the hydrophobic agent in the hydrophobic treatment ranges from 5% to 15%; And / or, the number of times of the hydrophobic treatment ranges from 1 to 5.

9. The preparation method according to claim 5 or 6, characterized in that: in, The drying equipment used for drying and heating the gas diffusion layer includes one or more of a blast oven, a vacuum oven, a microwave evaporator, and a nitrogen-filled oven; and / or and / or, the drying temperature when drying and heating the gas diffusion layer is in the range of 30° C. to 120° C.; and / or, the drying wind speed during the drying and heating of the gas diffusion layer is in the range of 0.1 m / s to 1.0 m / s; and / or, the absolute pressure value of the gas diffusion layer during drying and heating is in the range of 1 KPa to 201 KPa; And / or, the drying time when the gas diffusion layer is dried and heated is in the range of 5 min to 60 min; and / or, the drying atmosphere during the drying and heating treatment of the gas diffusion layer comprises one or more of nitrogen, nitrogen-oxygen mixed gas, oxygen, and CO2; and / or, the heating equipment used for drying and heating the gas diffusion layer includes: one or more of a microwave muffle furnace, a tubular furnace, a high temperature muffle furnace, and a resistance muffle furnace; and / or, the heating temperature when drying and heating the gas diffusion layer is in the range of 250° C. to 350° C.; and / or, the drying time when the gas diffusion layer is dried and heated is in the range of 60 min to 300 min; And / or, the drying atmosphere during the drying and heating treatment of the gas diffusion layer includes one or more of nitrogen, nitrogen-oxygen mixed gas, oxygen, and CO2.

10. A fuel cell, characterized in that: The fuel cell comprises the gas diffusion layer according to any one of claims 1 to 4 or the gas diffusion layer prepared according to any one of claims 5 to 9.

Images