CN117039006A - Gas diffusion layer, fuel cell and preparation method - Google Patents
Gas diffusion layer, fuel cell and preparation method Download PDFInfo
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- CN117039006A CN117039006A CN202311060858.2A CN202311060858A CN117039006A CN 117039006 A CN117039006 A CN 117039006A CN 202311060858 A CN202311060858 A CN 202311060858A CN 117039006 A CN117039006 A CN 117039006A
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- 238000009792 diffusion process Methods 0.000 title claims abstract description 60
- 239000000446 fuel Substances 0.000 title claims abstract description 31
- 238000002360 preparation method Methods 0.000 title abstract description 11
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 155
- 239000011148 porous material Substances 0.000 claims abstract description 53
- 239000002041 carbon nanotube Substances 0.000 claims abstract description 46
- 229910021393 carbon nanotube Inorganic materials 0.000 claims abstract description 46
- 239000000203 mixture Substances 0.000 claims abstract description 4
- 239000002002 slurry Substances 0.000 claims description 74
- 230000002209 hydrophobic effect Effects 0.000 claims description 33
- 229910052799 carbon Inorganic materials 0.000 claims description 26
- 239000002048 multi walled nanotube Substances 0.000 claims description 24
- 229920001343 polytetrafluoroethylene Polymers 0.000 claims description 24
- 239000004810 polytetrafluoroethylene Substances 0.000 claims description 24
- 239000003795 chemical substances by application Substances 0.000 claims description 21
- 239000000758 substrate Substances 0.000 claims description 19
- 238000000576 coating method Methods 0.000 claims description 14
- 239000011248 coating agent Substances 0.000 claims description 12
- 238000001035 drying Methods 0.000 claims description 12
- 239000002109 single walled nanotube Substances 0.000 claims description 12
- 239000004812 Fluorinated ethylene propylene Substances 0.000 claims description 9
- 239000002033 PVDF binder Substances 0.000 claims description 9
- HQQADJVZYDDRJT-UHFFFAOYSA-N ethene;prop-1-ene Chemical group C=C.CC=C HQQADJVZYDDRJT-UHFFFAOYSA-N 0.000 claims description 9
- 229920009441 perflouroethylene propylene Polymers 0.000 claims description 9
- -1 polytetrafluoroethylene Polymers 0.000 claims description 9
- 229920002981 polyvinylidene fluoride Polymers 0.000 claims description 9
- 239000002245 particle Substances 0.000 claims description 8
- 238000000034 method Methods 0.000 claims description 7
- 239000007789 gas Substances 0.000 abstract description 53
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 26
- 239000002737 fuel gas Substances 0.000 abstract description 4
- 230000035699 permeability Effects 0.000 abstract description 4
- 239000010410 layer Substances 0.000 description 200
- 239000012528 membrane Substances 0.000 description 23
- 239000002270 dispersing agent Substances 0.000 description 15
- 238000003756 stirring Methods 0.000 description 14
- 239000007788 liquid Substances 0.000 description 12
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 11
- 239000006185 dispersion Substances 0.000 description 9
- 230000000052 comparative effect Effects 0.000 description 8
- 239000002243 precursor Substances 0.000 description 8
- 239000002904 solvent Substances 0.000 description 8
- 238000005245 sintering Methods 0.000 description 7
- 238000005303 weighing Methods 0.000 description 6
- 239000012046 mixed solvent Substances 0.000 description 5
- 239000001267 polyvinylpyrrolidone Substances 0.000 description 5
- 235000013855 polyvinylpyrrolidone Nutrition 0.000 description 5
- 229920000036 polyvinylpyrrolidone Polymers 0.000 description 5
- 230000010287 polarization Effects 0.000 description 4
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 description 3
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 description 3
- 230000003197 catalytic effect Effects 0.000 description 3
- 238000002791 soaking Methods 0.000 description 3
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 230000002035 prolonged effect Effects 0.000 description 2
- 239000012495 reaction gas Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 238000010345 tape casting Methods 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000012512 characterization method Methods 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000003411 electrode reaction Methods 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000011229 interlayer Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 230000003014 reinforcing effect Effects 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
- H01M4/8605—Porous electrodes
- H01M4/861—Porous electrodes with a gradient in the porosity
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
- H01M4/88—Processes of manufacture
- H01M4/8803—Supports for the deposition of the catalytic active composition
- H01M4/8807—Gas diffusion layers
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/50—Fuel cells
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Inert Electrodes (AREA)
Abstract
The invention relates to a gas diffusion layer, a fuel cell and a preparation method. The gas diffusion layer comprises a basal layer, a first microporous layer and a second microporous layer which are sequentially laminated; the first microporous layer comprises first carbon powder; the second microporous layer comprises a mixture of second carbon powder and carbon nanotubes; the pore size of the micropores in the second microporous layer is smaller than that of the micropores in the first microporous layer. The first microporous layer has larger pore diameter and higher air permeability, the second microporous layer utilizes the pore diameter structure of the carbon nano tube, and the existence of small pore diameter pore channels is increased in the layer to form stronger capillary force, so that the removal of generated water under high current density is promoted. The gas diffusion layer enlarges the pore size distribution of the microporous layer, so that the pore size structure in the gas diffusion layer has the characteristics of multiple layers and multiple gradient distribution, the redistribution of water and gas in the gas diffusion layer is enhanced, the utilization rate of fuel gas is improved, and the performance of the fuel cell is improved.
Description
Technical Field
The invention relates to the technical field of fuel cells, in particular to a gas diffusion layer, a fuel cell and a preparation method.
Background
The proton exchange membrane fuel cell isA green novel energy source can convert chemical energy into electric energy, and CO does not exist in the conversion process 2 And CO and nitrogen-containing and sulfur-containing compounds. In addition, proton exchange membrane fuel cells are receiving attention from various countries because their raw material sources are clean and renewable. The gas diffusion layer is one of the key structures of the proton exchange membrane fuel cell, plays a role of 'gas-water-electricity-heat' conduction, and has an important influence on the performance of the proton exchange membrane fuel cell.
With the rapid development of proton exchange membrane fuel cells, the power requirements of the proton exchange membrane fuel cells are higher and higher, and the current density is increased along with the increase of the power. Under the condition of higher current density, the electrode reaction can generate a large amount of water in the proton exchange membrane fuel cell, and the generated water can influence the transmission of reaction gas in the proton exchange membrane fuel cell, so that the performance of the proton exchange membrane fuel cell is reduced.
Disclosure of Invention
Based on this, it is necessary to provide a gas diffusion layer capable of improving the performance of the fuel cell.
In addition, it is necessary to provide a method for preparing the gas diffusion layer.
In addition, it is also necessary to provide a fuel cell including the above gas diffusion layer.
A gas diffusion layer comprising a substrate layer, a first microporous layer and a second microporous layer which are sequentially laminated; the first microporous layer comprises first carbon powder; the second microporous layer comprises a mixture of second carbon powder and carbon nanotubes; the pore size of the micropores in the second microporous layer is smaller than that of the micropores in the first microporous layer.
In one embodiment, the micropores in the first microporous layer have a pore size of 10 μm to 15 μm; the pore diameter of the micropores in the second microporous layer is 2-5 μm.
In one embodiment, the first microporous layer further comprises a first hydrophobic agent.
In one embodiment, the first hydrophobic agent comprises one or more of polytetrafluoroethylene, polyvinylidene fluoride, fluorinated ethylene propylene.
In one embodiment, the second microporous layer further comprises a second hydrophobic agent.
In one embodiment, the second hydrophobic agent comprises one or more of polytetrafluoroethylene, polyvinylidene fluoride, fluorinated ethylene propylene;
in one embodiment, in the second microporous layer, the mass fraction of the second carbon powder is 50% -90%, and the mass fraction of the carbon nanotubes is 10% -50%.
In one embodiment, the particle size of the first carbon powder is 44 nm-52 nm, and the particle size of the second carbon powder is 32 nm-40 nm.
In one embodiment, the first carbon powder comprises at least one of XC72 carbon powder, li 435 carbon powder, and Li 400 carbon powder.
In one embodiment, the second carbon powder comprises at least one of XC72 carbon powder, li 435 carbon powder, and Li 400 carbon powder.
In one embodiment, the carbon nanotubes comprise at least one of multi-walled carbon nanotubes and single-walled carbon nanotubes.
In one embodiment, the multi-walled carbon nanotubes include at least one of G5 multi-walled carbon nanotubes, H4 multi-walled carbon nanotubes, H10 multi-walled carbon nanotubes, and G3 multi-walled carbon nanotubes.
In one embodiment, the single-walled carbon nanotubes comprise OH17 single-walled carbon nanotubes.
In one embodiment, the first microporous layer has a thickness of 5 μm to 30 μm. The thickness of the second microporous layer is 10-20 mu m.
In one embodiment, the substrate layer comprises carbon paper.
In one embodiment, the substrate layer is carbon paper containing a third hydrophobizing agent.
The method for preparing a gas diffusion layer according to any of the above embodiments, comprising the steps of:
preparing a first slurry containing the first carbon powder;
preparing a second slurry containing the second carbon powder and the carbon nanotubes;
coating the first slurry on the substrate layer, and drying to obtain a first slurry layer;
coating the second slurry on the first slurry layer, and drying to obtain a second slurry layer; and
the first slurry layer and the second slurry layer are heated to form the first microporous layer and the second microporous layer, respectively.
A fuel cell comprising a gas diffusion layer according to any one of the embodiments above.
The gas diffusion layer comprises a first microporous layer and a second microporous layer which are sequentially laminated on the substrate layer, wherein the first microporous layer contains first carbon powder, the second microporous layer contains carbon nano tubes except for the second carbon powder, the pore diameter of micropores in the second microporous layer is controlled to be smaller than that of micropores in the first microporous layer, the first microporous layer has larger pore diameter and higher air permeability, the second microporous layer utilizes the pore diameter structure of the carbon nano tubes, the existence of small pore diameter pore channels is increased in the layer, stronger capillary force is formed, and the removal of generated water under high current density is promoted. The gas diffusion layer enlarges the pore size distribution of the microporous layer, so that the pore size structure in the gas diffusion layer has the characteristics of multiple layers and multiple gradient distribution, the redistribution of water and gas in the gas diffusion layer is enhanced, the utilization rate of fuel gas is improved, and the performance of the fuel cell is improved.
Drawings
FIG. 1 is a schematic view of a gas diffusion layer according to the present invention;
FIG. 2 is a flow chart of the preparation of a gas diffusion layer according to the present invention;
FIG. 3 is a graph showing polarization performance of membrane electrodes prepared from the gas diffusion layers in examples 1 to 7 and comparative examples 1 to 2, respectively, of the present invention.
Detailed Description
In order that the invention may be readily understood, a more complete description of the invention will be rendered by reference to the appended drawings. Preferred embodiments of the present invention are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and/or" as used herein encompasses any and all combinations of one or more of the associated listed items.
As shown in fig. 1, the present invention provides a gas diffusion layer 100 including a base layer 110, a first microporous layer 120, and a second microporous layer 130, which are sequentially stacked. The first microporous layer 120 contains a first carbon powder. The second microporous layer 130 comprises a mixture of a second carbon powder and carbon nanotubes. The pore size of the micropores in the second microporous layer 130 is smaller than the pore size of the micropores in the first microporous layer 120.
The gas diffusion layer 100 includes a first microporous layer 120 and a second microporous layer 130 sequentially stacked on a substrate layer 110, where the first microporous layer 120 includes a first carbon powder, the second microporous layer 130 includes a carbon nanotube in addition to the second carbon powder, and the pore diameter of the micropores in the second microporous layer 130 is controlled to be smaller than that of the micropores in the first microporous layer 120, the first microporous layer 120 has a larger pore diameter and higher air permeability, the second microporous layer 130 utilizes the pore diameter structure of the carbon nanotube itself to increase the existence of small pore diameter pores in the layer, so as to form stronger capillary force and promote the removal of generated water under high current density. The gas diffusion layer 100 expands the pore size distribution of the microporous layer, so that the pore size structure in the gas diffusion layer 100 has the characteristics of multi-level and multi-gradient distribution, the redistribution of water and gas in the gas diffusion layer 100 is enhanced, the utilization rate of fuel gas is improved, and the performance of the fuel cell is improved.
In one embodiment, the particle size of the first carbon powder is 44nm to 52nm. In one embodiment, the first carbon powder comprises at least one of XC72 carbon powder, li 435 carbon powder, and Li 400 carbon powder.
In one embodiment, the first microporous layer 120 further comprises a first hydrophobic agent.
In one embodiment, the first hydrophobic agent comprises one or more of polytetrafluoroethylene, polyvinylidene fluoride, fluorinated ethylene propylene.
In one embodiment, the pores in the first microporous layer 120 have a pore size of 10 μm to 15 μm. In one embodiment, the thickness of the first microporous layer 120 is 5 μm to 30 μm. Further, the thickness of the first microporous layer 120 is 5 μm to 10 μm.
In one embodiment, the first microporous layer 120 includes a second carbon powder, carbon nanotubes, and a second hydrophobic agent.
In one embodiment, in the second microporous layer 130, the mass fraction of the second carbon powder is 50% -90%, and the mass fraction of the carbon nanotubes is 10% -50%. Further, in the second microporous layer 130, the mass fraction of the second carbon powder is 75% -80%, and the mass fraction of the carbon nanotubes is 20% -25%.
In one embodiment, the particle size of the second carbon powder is 32nm to 40nm. In one embodiment, the second carbon powder comprises at least one of XC72 carbon powder, li 435 carbon powder, and Li 400 carbon powder.
In one embodiment, the mass fraction of the carbon nanotubes in the second microporous layer 130 is 0.5% to 1.3%. In one embodiment, the diameter of the carbon nanotubes is 9nm to 12nm.
In one embodiment, the carbon nanotubes comprise at least one of multi-walled carbon nanotubes and single-walled carbon nanotubes. In one embodiment, the multi-walled carbon nanotubes comprise at least one of G5 multi-walled carbon nanotubes, H4 multi-walled carbon nanotubes, H10 multi-walled carbon nanotubes, and G3 multi-walled carbon nanotubes. In one embodiment, the single-walled carbon nanotubes comprise OH17 single-walled carbon nanotubes.
In one embodiment, the mass fraction of the second hydrophobic agent in the second microporous layer 130 is 1% to 5%. In one embodiment, the second hydrophobic agent comprises one or more of polytetrafluoroethylene, polyvinylidene fluoride, fluorinated ethylene propylene.
Wherein the pore size of the micropores in the second microporous layer 130 is smaller than the pore size of the micropores in the first microporous layer 120. In one embodiment, the micropores in the second microporous layer 130 have a pore size of 2 μm to 5 μm. In one embodiment, the thickness of the second microporous layer 130 is 10 μm to 20 μm. Further, the thickness of the second microporous layer 130 is 10 μm to 15 μm.
In one embodiment, the substrate layer 110 is carbon paper.
The substrate layer 110 may also contain a third hydrophobic agent therein. In one embodiment, the third hydrophobic agent comprises one or more of polytetrafluoroethylene, polyvinylidene fluoride, fluorinated ethylene propylene.
Referring to fig. 2, the present invention further provides a method for preparing the gas diffusion layer 100, which includes the following steps:
step S11, providing a base layer 110.
Step S12, preparing a first slurry containing first carbon powder.
In one embodiment, a first carbon powder, a first dispersant and a first hydrophobizing agent are dispersed in a first solvent to obtain a first slurry.
In one embodiment, the particle size of the first carbon powder is 44nm to 52nm. In one embodiment, the first carbon powder comprises at least one of XC72 carbon powder, li 435 carbon powder, and Li 400 carbon powder.
In one embodiment, the first dispersant includes at least one of PVP (polyvinylpyrrolidone), a ZetaSperse 3100 dispersant, and a ZetaSperse 3600 dispersant.
In one embodiment, the first hydrophobic agent comprises one or more of polytetrafluoroethylene, polyvinylidene fluoride, fluorinated ethylene propylene.
In one embodiment, the first solvent is water.
More specifically, adding first carbon powder and PVP into water, stirring to obtain a first slurry precursor liquid, adding PTFE dispersion with the mass fraction of 6% -10% into the first slurry precursor liquid, and stirring at a stirring speed of 150rpm-250rpm for 30-120 min to obtain the first slurry.
Step S13, preparing a second slurry containing second carbon powder and carbon nanotubes.
In one embodiment, the second carbon powder, the carbon nanotubes, the second dispersant and the second hydrophobic agent are dispersed in a second solvent to obtain a second slurry.
In one embodiment, the particle size of the second carbon powder is 32nm to 40nm. In one embodiment, the second carbon powder comprises at least one of XC72 carbon powder, li 435 carbon powder, and Li 400 carbon powder.
It is understood that the diameter of the carbon nanotubes is nano-scale, for example, 9nm to 12nm.
In one embodiment, the carbon nanotubes comprise at least one of multi-walled carbon nanotubes and single-walled carbon nanotubes. In one embodiment, the multi-walled carbon nanotubes comprise at least one of G5 multi-walled carbon nanotubes, H4 multi-walled carbon nanotubes, H10 multi-walled carbon nanotubes, and G3 multi-walled carbon nanotubes. In one embodiment, the single-walled carbon nanotubes may be OH17 single-walled carbon nanotubes.
In an embodiment, the second dispersant includes at least one of PVP, zetaSperse 3100 dispersant and ZetaSperse 3600 dispersant.
In one embodiment, the second hydrophobic agent comprises one or more of polytetrafluoroethylene, polyvinylidene fluoride, fluorinated ethylene propylene.
In one embodiment, the second solvent is a mixed solvent composed of water and an alcohol, and the alcohol includes at least one of ethanol, isopropanol, ethylene glycol, and glycerol. In one embodiment, the volume ratio of water to alcohol in the second solvent is 1:3.
More specifically, adding second carbon powder, carbon nano tube and PVP into a second solvent composed of water and alcohol, stirring to obtain second slurry precursor liquid, adding PTFE dispersion liquid with the mass fraction of 10% -50% into the second slurry precursor liquid, and stirring at a stirring speed of 150-250 rpm for 30-120 min to obtain second slurry.
In step S14, the first slurry is coated on the substrate layer 110, and the first slurry layer is obtained after drying.
Specifically, the first paste is coated on the base layer 110 under the condition of 100 μm to 300 μm, and dried at the temperature of 60 ℃ to 100 ℃ for 30 minutes, thereby obtaining the first paste layer. Wherein, under the condition of 100-300 μm, the thickness of the first slurry layer before drying is 100-300 μm.
In one embodiment, the coating method may be a knife coating method. In one embodiment, the substrate layer 110 may be secured to a blade before the first paste is coated on the substrate layer 110 to facilitate subsequent blade coating of the first paste on the substrate layer 110.
And S15, coating the second slurry on the first slurry layer, and drying to obtain the second slurry layer.
Specifically, the second slurry is coated on the first slurry layer under the condition of 300-400 mu m, and is dried at the temperature of 80-120 ℃ to obtain the second slurry layer. Wherein, under the condition of 300 μm to 400 μm, the thickness of the second slurry layer before drying is 300 μm to 400 μm.
In one embodiment, the coating method may be a knife coating method.
Step S16, heating the first slurry layer and the second slurry layer to form the first microporous layer 120 and the second microporous layer 130, respectively, thereby obtaining the gas diffusion layer 100.
Specifically, sintering the first slurry layer at a temperature of 330 to 400 ℃ to remove the first dispersant and the first solvent in the first slurry layer, thereby forming the first slurry layer into the first microporous layer 120; the second slurry layer is sintered at a temperature of 330-400 deg.c to remove the second dispersant and the second solvent in the second slurry layer, thereby forming the second microporous layer 130 from the second slurry layer.
Wherein the base layer 110, the first microporous layer 120, and the second microporous layer 130 together comprise the gas diffusion layer 100.
After the gas diffusion layer 100 is prepared, a proton exchange membrane and a catalytic side portion may be prepared, and a membrane electrode may be finally prepared. It will be appreciated that after the membrane electrode is prepared, the fuel cell may be further prepared by subsequent steps.
At least one embodiment of the present invention provides a fuel cell comprising a gas diffusion layer 100.
In one embodiment, the fuel cell may be a proton exchange membrane fuel cell. Specifically, the proton exchange membrane fuel cell includes a proton exchange membrane, a catalytic layer, and a gas diffusion layer 100. Wherein the catalytic layer is located between the proton exchange membrane and the gas diffusion layer 100.
In summary, the invention has the following beneficial effects:
the gas diffusion layer comprises a first microporous layer and a second microporous layer which are sequentially laminated on a substrate layer, wherein the first microporous layer comprises first carbon powder, the second microporous layer comprises carbon nano tubes besides the second carbon powder, the pore diameter of micropores in the second microporous layer is controlled to be smaller than that of micropores in the first microporous layer, the first microporous layer has larger pore diameter and higher air permeability, the second microporous layer utilizes the pore diameter structure of the carbon nano tubes, small pore diameter pore channels are added in the layer, so that stronger capillary force is formed, and the removal of generated water under high current density is promoted. The gas diffusion layer enlarges the pore size distribution of the microporous layer, so that the pore size structure in the gas diffusion layer has the characteristics of multiple layers and multiple gradient distribution, the redistribution of water and gas in the gas diffusion layer is enhanced, the utilization rate of fuel gas is improved, and the performance of the fuel cell is improved.
And (II) the second microporous layer comprises carbon nano tubes, so that the pore size distribution in the gas diffusion layer is enlarged, and the existence of small pore size pore channels is increased, thereby enhancing the water drainage effect of cathode generated water under higher current density, and further improving the performance of the fuel cell. That is, the carbon nanotubes in the second microporous layer of the present invention can provide a sufficient amount of suitable pore size for the gas diffusion layer, and provide a certain motive force for generating water channels in the electrodes of the fuel cell, thereby facilitating the removal of water.
The invention utilizes the self pore diameter structure of the carbon nano tube and the composite characteristic of the carbon nano tube and carbon powder, namely the carbon nano tube is used as a reinforcing structure and can be combined with the carbon powder, so that the cohesiveness of the first microporous layer and the second microporous layer is enhanced, the service lives of the first microporous layer and the second microporous layer are prolonged, and the service lives of the gas diffusion layer and the fuel cell are prolonged.
And (IV) the invention can improve the pore diameter structure of the surface of the second microporous layer and improve the resistance value of the second microporous layer by controlling the proportion of the carbon nano tubes in the second microporous layer. Meanwhile, depending on the difference of pore diameter structures of the carbon nano tubes, multiple interlayer spacing structures can be formed, and the small-pore-diameter carbon nano tubes can keep the moisture of the fuel cell as much as possible at the initial stage of reaction, wet the proton exchange membrane and enable proton channels to be smooth.
The gas diffusion layer provided by the invention comprises a substrate layer, and a first microporous layer and a second microporous layer which are sequentially laminated on the substrate layer, wherein the first microporous layer is slightly immersed in the substrate layer, so that the cohesiveness between the first microporous layer and the substrate layer is enhanced, and the defects of the first microporous layer can be made up due to smaller pore diameter of micropores in the second microporous layer, so that stronger capillary force is formed, the removal of water generated under high current density is promoted, and the redistribution of water and reaction gas is formed.
The invention is further illustrated by the following specific examples and comparative examples.
Example 1
(1) Taking carbon paper with the size of 6cm by 6cm, weighing after drying, then placing the carbon paper in PTFE dispersion liquid with the mass fraction of 1% for soaking for 5min, taking out, sintering at the temperature of 350 ℃, weighing, and calculating the mass fraction of PTFE to obtain the hydrophobic carbon paper. Wherein, in the hydrophobic carbon paper, the mass fraction of PTFE is 3%.
(2) 8g of carbon powder was weighed, the weighed carbon powder and 3.2g of dispersant ZetaSperse 3100 were added to 100g of water, and stirred at 5000rpm for 60 minutes to obtain a first slurry precursor liquid, and then 5.7g of PTFE dispersion was added dropwise at a stirring speed of 200rpm, and stirred for 2 hours to obtain a first slurry.
(3) 7.2g of carbon powder and 0.8g of carbon nano tube are weighed, the weighed carbon powder, the weighed carbon nano tube and a dispersing agent ZetaSperse 3100 are added into a mixed solvent consisting of water and alcohol, the volume ratio of water and alcohol in the mixed solvent is set to be 1:3, the mass ratio of the carbon powder to the dispersing agent is controlled to be 5:2, stirring is carried out for 60min at a rotation speed of 5000rpm, a second slurry precursor liquid is obtained, then 5.7g of PTFE dispersion is dropwise added at a stirring speed of 200rpm, and stirring is carried out for 2h, thus obtaining a second slurry.
(4) The hydrophobic carbon paper was fixed on a blade coater, and the first slurry was coated on the hydrophobic carbon paper under 200 μm conditions, and dried at 60 ℃ for 30min to obtain a first slurry layer.
(5) And coating the second slurry on the first slurry layer under the condition of 350 mu m, and drying at the temperature of 80-120 ℃ for 1h to obtain the second slurry layer.
(6) Sintering the first slurry layer and the second slurry layer at the temperature of 350 ℃ for 60min to form a first microporous layer and a second microporous layer respectively, thereby obtaining the gas diffusion layer.
Example 2
The preparation method of example 2 is substantially the same as that of example 1, except that:
in the step (3), the mass of the weighed carbon powder is 6.4g, and the mass of the weighed carbon nano tube is 1.6g.
Example 3
The preparation method of example 5 is substantially the same as that of example 1, except that:
in the step (3), the mass of the weighed carbon powder is 5.6g, and the mass of the weighed carbon nano tube is 2.4g.
Example 4
The preparation method of example 4 is substantially the same as that of example 1, except that:
in the step (3), the mass of the carbon powder is 4g, and the mass of the carbon nano tube is 4g.
Example 5
The preparation method of example 5 is substantially the same as that of example 1, except that:
in step (4), the condition for coating the first slurry on the hydrophobic carbon paper is 300 μm.
Example 6
The preparation method of example 6 was substantially the same as that of example 1, except that:
in the step (4), the condition of coating the first slurry on the hydrophobic carbon paper is 300 μm;
in step (5), the condition for coating the second slurry on the first slurry layer was 450 μm.
Example 7
The preparation method of example 7 is substantially the same as that of example 1, except that:
in the step (4), the condition of coating the first slurry on the hydrophobic carbon paper is 300 μm;
in step (5), the condition for coating the second slurry on the first slurry layer was 500 μm.
Comparative example 1
(1) Taking carbon paper with the size of 6cm by 6cm, weighing after drying, then placing the carbon paper in PTFE dispersion liquid with the mass fraction of 1% for soaking for 5min, taking out, sintering at the temperature of 350 ℃, weighing, and calculating the mass fraction of PTFE to obtain the hydrophobic carbon paper. Wherein, in the hydrophobic carbon paper, the mass fraction of PTFE is 3%.
(2) 8g of carbon powder was weighed, the weighed carbon powder and 3.2g of dispersant ZetaSperse 3100 were added to 100g of water, stirred at 5000rpm for 60 minutes to obtain a slurry precursor liquid, and then 5.7g of PTFE dispersion was added dropwise at a stirring speed of 200rpm, and stirred for 2 hours to obtain a slurry.
(3) The hydrophobic carbon paper was fixed on a blade plate, and the slurry was coated on the hydrophobic carbon paper under 300 μm conditions, and dried at 60 ℃ for 30min to obtain a slurry layer.
(4) Sintering the slurry layer at 350 ℃ for 60min to form a microporous layer, thereby obtaining the gas diffusion layer.
Comparative example 2
(1) Taking carbon paper with the size of 6cm by 6cm, weighing after drying, then placing the carbon paper in PTFE dispersion liquid with the mass fraction of 1% for soaking for 5min, taking out, sintering at the temperature of 350 ℃, weighing, and calculating the mass fraction of PTFE to obtain the hydrophobic carbon paper. Wherein, in the hydrophobic carbon paper, the mass fraction of PTFE is 3%.
(2) 7.2g of carbon powder and 0.8g of carbon nano tube are weighed, the weighed carbon powder, the weighed carbon nano tube and the dispersing agent are added into a mixed solvent composed of water and alcohol, the volume ratio of water and alcohol in the mixed solvent is set to be 1:3, stirring is carried out for 60min at a rotation speed of 5000rpm, slurry precursor liquid is obtained, then 5.7g of PTFE dispersion is dropwise added at a stirring speed of 200rpm, and the slurry is obtained after stirring for 2 h.
(3) The hydrophobic carbon paper was fixed on a blade plate, and the slurry was coated on the hydrophobic carbon paper under 300 μm conditions, and dried at 60 ℃ for 30min to obtain a slurry layer.
(4) Sintering the slurry layer at 350 ℃ for 60min to form a microporous layer, thereby obtaining the gas diffusion layer.
The gas diffusion layers produced in examples 1 to 7 and comparative examples 1 to 2 were subjected to physical and chemical property characterization. Specifically, the mass fraction of the carbon nanotubes in the corresponding microporous layer, the thickness of the second microporous layer, and the average pore size of the microporous layers (i.e., the first microporous layer and the second microporous layer) were separately tested, and the test results are shown in table 1 below.
TABLE 1 mass fraction of carbon nanotubes in the corresponding microporous layer, thickness of microporous layer, pore size data of microporous layer in examples 1 to 7 and comparative examples 1 to 2
From the test results in table 1 above, it is understood that the higher the carbon nanotube content, the lower the pore size of the second microporous layer, and the pore size of the second microporous layer decreases as the thickness of the second microporous layer increases.
The gas diffusion layers prepared in examples 1 to 7 and comparative examples 1 to 2 were subjected to subsequent steps to prepare membrane electrodes, and the prepared membrane electrodes were subjected to polarization performance test.
Referring to fig. 3, it can be seen that the polarization performance of the membrane electrode prepared by the gas diffusion layers in examples 1-7 through the subsequent steps is better than that of the membrane electrode prepared by the gas diffusion layers in comparative examples 1-2 through the subsequent steps, which indicates that the gas diffusion layers prepared by the present invention can improve the polarization performance of the membrane electrode. Of which the voltage and power of example 2 were highest.
The technical features of the above embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The foregoing examples illustrate only a few embodiments of the invention, which are described in detail and are not to be construed as limiting the scope of the claims. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.
Claims (10)
1. A gas diffusion layer, which is characterized by comprising a basal layer, a first microporous layer and a second microporous layer which are sequentially laminated; the first microporous layer comprises first carbon powder; the second microporous layer comprises a mixture of second carbon powder and carbon nanotubes; the pore size of the micropores in the second microporous layer is smaller than that of the micropores in the first microporous layer.
2. The gas diffusion layer of claim 1, wherein the micropores in the first microporous layer have a pore size of 10 μm to 15 μm; the pore diameter of the micropores in the second microporous layer is 2-5 μm.
3. The gas diffusion layer of claim 1, wherein said first microporous layer further comprises a first hydrophobic agent;
preferably, the first hydrophobic agent comprises one or more of polytetrafluoroethylene, polyvinylidene fluoride, fluorinated ethylene propylene.
4. The gas diffusion layer of claim 1, wherein said second microporous layer further comprises a second hydrophobic agent;
preferably, the second hydrophobic agent comprises one or more of polytetrafluoroethylene, polyvinylidene fluoride, fluorinated ethylene propylene;
preferably, in the second microporous layer, the mass fraction of the second carbon powder is 50% -90%, and the mass fraction of the carbon nanotubes is 10% -50%.
5. A gas diffusion layer according to any one of claims 1 to 4, wherein the first carbon powder has a particle size of 44nm to 52nm and the second carbon powder has a particle size of 32nm to 40nm;
preferably, the first carbon powder comprises at least one of XC72 carbon powder, li 435 carbon powder and Li 400 carbon powder;
preferably, the second carbon powder comprises at least one of XC72 carbon powder, li 435 carbon powder, and Li 400 carbon powder.
6. The gas diffusion layer of any one of claims 1 to 4, wherein the carbon nanotubes comprise at least one of multi-walled carbon nanotubes and single-walled carbon nanotubes;
preferably, the multi-walled carbon nanotube includes at least one of a G5 multi-walled carbon nanotube, an H4 multi-walled carbon nanotube, an H10 multi-walled carbon nanotube, and a G3 multi-walled carbon nanotube;
preferably, the single-walled carbon nanotubes comprise OH17 single-walled carbon nanotubes.
7. The gas diffusion layer according to any one of claims 1 to 4, wherein the thickness of the first microporous layer is 5 μm to 30 μm and the thickness of the second microporous layer is 10 μm to 20 μm.
8. The gas diffusion layer according to any one of claims 1 to 4, wherein the base layer comprises carbon paper;
preferably, the substrate layer is carbon paper containing a third hydrophobizing agent.
9. A method of producing the gas diffusion layer according to any one of claims 1 to 8, comprising the steps of:
preparing a first slurry containing the first carbon powder;
preparing a second slurry containing the second carbon powder and the carbon nanotubes;
coating the first slurry on the substrate layer, and drying to obtain a first slurry layer;
coating the second slurry on the first slurry layer, and drying to obtain a second slurry layer; and
the first slurry layer and the second slurry layer are heated to form the first microporous layer and the second microporous layer, respectively.
10. A fuel cell comprising the gas diffusion layer according to any one of claims 1 to 8.
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