CN116387536A - Gas diffusion layer, membrane electrode assembly, fuel cell and electricity utilization device - Google Patents
Gas diffusion layer, membrane electrode assembly, fuel cell and electricity utilization device Download PDFInfo
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Classifications
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- 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
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/10—Fuel cells with solid electrolytes
- H01M8/1004—Fuel cells with solid electrolytes characterised by membrane-electrode assemblies [MEA]
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/10—Fuel cells with solid electrolytes
- H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
- H01M8/1018—Polymeric electrolyte materials
- H01M8/1041—Polymer electrolyte composites, mixtures or blends
- H01M8/1046—Mixtures of at least one polymer and at least one additive
- H01M8/1048—Ion-conducting additives, e.g. ion-conducting particles, heteropolyacids, metal phosphate or polybenzimidazole with phosphoric acid
-
- 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
Abstract
The invention relates to the technical field of fuel cell materials, in particular to a gas diffusion layer, a membrane electrode assembly, a fuel cell and an electric device. The gas diffusion layer comprises a substrate layer and a microporous layer arranged on the substrate layer, wherein the components of the microporous layer comprise: carbon powder, a binder and a metal oxide. The gas diffusion layer adopts the metal oxide doping method to add the metal oxide into the microporous layer, is applied to the high-temperature fuel cell taking the phosphoric acid doped polymer film as the proton exchange film, and along with the high-temperature operation of the fuel cell, the phosphoric acid in the proton exchange film is vaporized and moved into the gas diffusion layer and reacts with the metal oxide in the microporous layer to generate phosphate, so that the corrosion of the phosphoric acid to carbon powder in the microporous layer is reduced, the phosphoric acid corrosion resistance and the electrochemical corrosion resistance of the gas diffusion layer are improved, and the service life of the high-temperature fuel cell is prolonged.
Description
Technical Field
The invention relates to the technical field of fuel cell materials, in particular to a gas diffusion layer, a membrane electrode assembly, a fuel cell and an electric device.
Background
The fuel cell is a high-efficiency pollution-free power generation cell, and the most widely used fuel cell is a proton exchange membrane fuel cell at present. The proton exchange membrane fuel cell can be classified into a high temperature proton exchange membrane fuel cell (High Temperature Proton Exchange Membrane Fuel Cell, HT-PEMFC) and a low temperature proton exchange fuel cell (Low Temperature Proton Exchange Membrane Fuel Cell, LT-PEMFC) according to the temperature at the time of operation. The operating temperature of the HT-PEMFC is 160-220 ℃, the operating temperature of the LT-PEMFC is 60-95 ℃ generally, and the higher operating temperature can not only improve the electrochemical reaction rate, but also improve the CO poisoning resistance of the noble metal Pt/C catalyst. Therefore, the HT-PEMFC has lower purity requirement on the hydrogen at the anode side, and has more application scenes compared with the LT-PEMFC.
The main functional structure of the fuel cell is a membrane electrode, and specifically comprises a proton exchange membrane, a catalytic layer and a gas diffusion layer, wherein the proton exchange membrane is an insulator and is used for dividing an anode and a cathode to prevent direct mixing of fuel and air from chemical reaction; the catalytic layers on the two sides are places where fuel and oxidant perform electrochemical reaction; the outermost gas diffusion layer has the main function of a diffusion medium for fuel gas, oxygen, reaction products and electrons, and has high electrical conductivity, high thermal conductivity, corrosion resistance and hydrophobicity. The mechanisms for shortening the service life and degrading the performance of the fuel cell mainly include: migration and dissolution of catalyst atoms, corrosion of catalyst support carbon; chemical, thermal and mechanical attenuation of proton exchange membranes; the carbon in the gas diffusion layer is corroded, so that the microporous structure is changed, the transmission of reaction raw materials and products is not facilitated, and meanwhile, the resistivity is increased. Therefore, the preparation of a gas diffusion layer having good corrosion resistance and conductivity is of great importance for improving the life of a fuel cell.
Disclosure of Invention
Based on the above, the invention provides a gas diffusion layer which is applied to a fuel cell and can prolong the service life of the fuel cell.
A first object of the present invention is to provide a gas diffusion layer comprising a base layer and a microporous layer provided on the base layer, the components of the microporous layer comprising: carbon powder, a binder and a metal oxide.
In some specific embodiments, the microporous layer comprises the components in parts by weight: 60-85 parts of carbon powder, 10-30 parts of binder and 1-10 parts of metal oxide.
In some specific embodiments, the microporous layer comprises the components in mass percent: 60-85% of carbon powder, 10-30% of binder and 1-10% of metal oxide.
In some specific embodiments, the microporous layer comprises the components in mass percent: 70-80% of carbon powder, 15-25% of binder and 3-8% of metal oxide.
In some specific embodiments, the metal oxide is capable of reacting with phosphoric acid at a temperature of 160-220 ℃ to form a phosphate.
In some specific embodiments, the metal oxide is selected from the group consisting of Fe 2 O 3 、Al 2 O 3 、MnO 2 And one or more of MgO.
In some specific embodiments, the metal oxide has a particle size of 40nm to 100nm.
In some specific embodiments, the carbon powder is one or more of XC-72, XC-72R, ketjen black, carbon nanotubes, graphene, and graphite.
In some specific embodiments, the carbon powder has a particle size of 30nm to 500nm.
In some specific embodiments, the binder is one or more of polytetrafluoroethylene, perfluoroethylene propylene copolymer, tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer, and polysilazane resin.
In some specific embodiments, the base layer has a thickness of 150 μm to 200 μm.
In some specific embodiments, the microporous layer has a thickness of 20 μm to 50 μm.
The second object of the present invention is to provide a method for preparing the gas diffusion layer, comprising:
s1, mixing carbon powder with alcohol and water to obtain carbon powder treatment liquid;
s2, mixing the carbon powder treatment liquid with a binder and a metal oxide to obtain microporous layer slurry;
and S3, coating the microporous layer slurry on the surface of the substrate layer, and drying and sintering to form the microporous layer to obtain the gas diffusion layer.
In some specific embodiments, the volume ratio of the alcohol to the water is 1:0.1-1; the alcohol is one or more of methanol, n-propanol, isopropanol, ethylene glycol and n-butanol.
In some specific embodiments, the binder is added in the form of a binder emulsion, the components of the binder emulsion comprising: the adhesive comprises an adhesive, a surfactant and water, wherein the adhesive accounts for 10-20% of the mass of the adhesive emulsion.
In some specific embodiments, the microporous layer slurry has a solids content of 8% to 30%.
In some specific embodiments, the sintering process is performed under an inert atmosphere at a sintering temperature of 200 to 380 ℃ for a sintering time of 0.5 to 2 hours.
A third object of the present invention provides the use of the gas diffusion layer described above in a high temperature fuel cell.
The fourth object of the invention is to provide a membrane electrode assembly, which comprises a first gas diffusion layer, a first catalytic layer, a proton exchange membrane, a second catalytic layer and a second gas diffusion layer which are sequentially stacked, wherein the first gas diffusion layer and/or the second gas diffusion layer is/are the gas diffusion layers.
In some specific embodiments, the proton exchange membrane is a phosphoric acid doped polymer membrane.
A fifth object of the present invention is to provide a fuel cell comprising the above membrane electrode assembly and bipolar plates provided on both sides of the membrane electrode assembly.
A sixth object of the present invention is to provide an electric power consumption device including the above-described fuel cell.
Compared with the prior art, the invention has the following beneficial effects:
according to the gas diffusion layer, the metal oxide is added into the microporous layer by adopting the metal oxide doping method, so that the gas diffusion layer is applied to a high-temperature fuel cell taking a polymer membrane doped with phosphoric acid as a proton exchange membrane, and along with the high-temperature operation of the fuel cell, phosphoric acid in the proton exchange membrane is vaporized and moved into the gas diffusion layer and reacts with the metal oxide in the microporous layer to generate phosphate, so that the corrosion of phosphoric acid to carbon powder in the microporous layer is reduced, and the phosphoric acid corrosion resistance and electrochemical corrosion resistance of the gas diffusion layer are improved, so that the service life of the high-temperature fuel cell is prolonged.
The preparation method of the gas diffusion layer has the advantages of wide sources of raw materials, simple preparation process and mild conditions, and is suitable for industrial application.
Drawings
FIG. 1 is a graph showing the polarization of a gas diffusion layer according to example 1 of the present invention before and after an aging test of a fuel cell;
FIG. 2 is a graph showing the polarization of the gas diffusion layer according to example 2 before and after aging test of the fuel cell;
fig. 3 is a graph showing polarization curves before and after the gas diffusion layer according to comparative example 1 is applied to a fuel cell for an aging test.
Detailed Description
In order that the invention may be readily understood, a more particular description of the invention will be rendered by reference to specific embodiments that are illustrated in the appended 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.
Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the invention, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise. In the description of the present invention, the meaning of "several" means at least one, such as one, two, etc., unless specifically defined otherwise.
The words "preferably," "more preferably," and the like in the present invention refer to embodiments of the invention that may provide certain benefits in some instances. However, other embodiments may be preferred under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, nor is it intended to exclude other embodiments from the scope of the invention.
When a range of values is disclosed herein, the range is considered to be continuous and includes both the minimum and maximum values for the range, as well as each value between such minimum and maximum values. Further, when a range refers to an integer, each integer between the minimum and maximum values of the range is included. Further, when multiple range description features or characteristics are provided, the ranges may be combined. In other words, unless otherwise indicated, all ranges disclosed herein are to be understood to include any and all subranges subsumed therein.
All percentages, fractions and ratios are calculated on the total mass of the composition of the invention, unless otherwise indicated. All of the mass of the ingredients listed, unless otherwise indicated, are given to the active substance content and therefore they do not include solvents or by-products that may be included in commercially available materials. The term "mass percent" herein may be represented by the symbol "%". All molecular weights herein are weight average molecular weights expressed in daltons, unless indicated otherwise. All formulations and tests herein take place in an environment of 25 ℃, unless otherwise indicated. The terms "comprising," "including," "containing," "having," or other variations thereof herein are intended to cover a non-closed inclusion, without distinguishing between them. The term "comprising" means that other steps and ingredients may be added that do not affect the end result. The compositions and methods/processes of the present invention comprise, consist of, and consist essentially of the essential elements and limitations described herein, as well as additional or optional ingredients, components, steps, or limitations of any of the embodiments described herein. The terms "efficacy," "performance," "effect," "efficacy" are not differentiated herein.
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 includes any and all combinations of one or more of the associated listed items.
In the HT-PEMFC taking a polymer membrane doped with phosphoric acid as a proton exchange membrane, the phosphoric acid in the polymer membrane is vaporized to penetrate through a catalytic layer and to penetrate into a gas diffusion layer in the high-temperature operation process, on one hand, the phosphoric acid causes chemical corrosion to carbon powder of a microporous layer, and on the other hand, when phosphoric acid electrolyte exists, the carbon powder generates high-potential electrochemical corrosion under the condition of battery counter electrode, so that the resistance of the gas diffusion layer is increased, the current density is reduced, and the service life of the HT-PEMFC is reduced.
Based on this, an embodiment of the present invention provides a gas diffusion layer. The gas diffusion layer comprises a gas diffusion layer comprising a substrate layer and a microporous layer arranged on the substrate layer, wherein the components of the microporous layer comprise: carbon powder, a binder and a metal oxide.
In some of these embodiments, the metal oxide is capable of reacting with phosphoric acid at a temperature of 160 to 220 DEG CGenerating phosphate by the reaction. In particular, the metal oxide may be Fe 2 O 3 、Al 2 O 3 、MnO 2 And MgO, preferably the metal oxide is Al 2 O 3 。
Further, the metal oxide may be nano-sized metal oxide powder, and as an example, the particle size thereof may be 40nm to 100nm.
The metal oxide can react with phosphoric acid at about 200deg.C to produce corresponding phosphate and water, and Fe 2 O 3 And Al 2 O 3 For example, the reaction equation is as follows:
Fe 2 O 3 +3H 3 PO 4 →Fe 3 (PO 4 ) 2 +3H 2 O
Al 2 O 3 +6H 3 PO 4 →2Al(H 2 PO 4 ) 3 +3H 2 O
the reaction condition is close to the operation temperature of HT-PEMFC, when the fuel cell is operated at about 200 ℃, phosphoric acid migrating to the gas diffusion layer through the proton exchange membrane reacts with the metal oxide at the operation temperature, so that the corrosion of the phosphoric acid to carbon powder is slowed down, and the service life of the gas diffusion layer is prolonged.
In some embodiments, the microporous layer comprises the components in parts by weight: 60-85 parts of carbon powder, 10-30 parts of binder and 1-10 parts of metal oxide.
It is understood that carbon powder includes, but is not limited to, 60 parts, 62 parts, 64 parts, 65 parts, 68 parts, 70 parts, 72 parts, 75 parts, 78 parts, 80 parts, 82 parts, 85 parts by weight; binders include, but are not limited to, 10 parts, 12 parts, 14 parts, 15 parts, 16 parts, 18 parts, 20 parts, 22 parts, 25 parts, 28 parts, 30 parts; the metal oxides include, but are not limited to, 1 part, 2 parts, 4 parts, 5 parts, 6 parts, 8 parts, 10 parts.
The following holds true for the range that any two of these point values may be made up as end values in some examples.
In some embodiments, the microporous layer comprises the components in mass percent: 60-85% of carbon powder, 10-30% of binder and 1-10% of metal oxide.
It is understood that carbon powders include, but are not limited to, 60%, 62%, 64%, 65%, 68%, 70%, 72%, 75%, 78%, 80%, 82%, 85% by weight; binders include, but are not limited to, 10%, 12%, 14%, 15%, 16%, 18%, 20%, 22%, 25%, 28%, 30%; the metal oxides include, but are not limited to, 1%, 2%, 4%, 5%, 6%, 8%, 10%.
The following holds true for the range that any two of these point values may be made up as end values in some examples.
Further, the microporous layer comprises the following components in percentage by mass: 70-80% of carbon powder, 15-25% of binder and 3-8% of metal oxide.
When the metal oxide content is too low, the effect of absorbing phosphoric acid is weak, and when the metal oxide content is too high, the resistance of the gas diffusion layer increases.
In some of these embodiments, the carbon powder may be one or more of XC-72, XC-72R, ketjen black, carbon nanotubes, graphene, or graphite. Further, the carbon powder can be nano-scale carbon powder, and the particle size is 30 nm-500 nm.
In some of these embodiments, the binder is one or more of Polytetrafluoroethylene (PTFE), perfluoroethylene propylene copolymer (FEP), tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer (PFA), and polysilazane resin. Polytetrafluoroethylene (PTFE) is preferred.
In some of these embodiments, the base layer in the gas diffusion layer is a carbon fiber layer. The carbon fiber layer is formed by stacking carbon fibers. Further, the thickness of the base layer is 150-200 μm, and the pore radius is 10-30 μm.
In some of these embodiments, the microporous layer has a thickness of 20 μm to 50 μm and a pore radius of less than 100nm.
According to the invention, the metal oxide is doped in the microporous layer, so that the metal oxide can react with phosphoric acid entering the gas diffusion layer when the high-temperature fuel cell is operated, the corrosion of phosphoric acid to carbon powder in the microporous layer is reduced, the phosphoric acid corrosion resistance and electrochemical corrosion resistance of the gas diffusion layer are improved, and the service life of the high-temperature fuel cell is prolonged.
The invention can ensure the conductivity of the gas diffusion layer and furthest slow down the corrosion of phosphoric acid to carbon powder in the microporous layer by further controlling the proportion of metal oxide in the microporous layer, so that the microporous layer has stable structure, the air permeability of the gas diffusion layer is ensured, the attenuation of the gas diffusion layer is slowed down, and the service life of the high-temperature fuel cell is prolonged.
Another embodiment of the present invention provides a method for preparing the above gas diffusion layer, comprising the following steps S1 to S3.
S1, mixing carbon powder with alcohol and water to obtain carbon powder treatment liquid.
In the step, the volume ratio of the alcohol to the water is 1:0.1-1, and the alcohol can be one or more selected from methanol, n-propanol, isopropanol, ethylene glycol and n-butanol, preferably the alcohol is isopropanol and ethylene glycol. The mixing process in this step may be carried out by grinding for 1-2 hours with a sand mill at 2000-2500 rpm.
And S2, mixing the carbon powder treatment liquid with a binder and a metal oxide to obtain microporous layer slurry.
In this step, the binder is added in the form of a binder emulsion comprising the components: the adhesive accounts for 10-20% of the mass of the adhesive emulsion, can be prepared by self, or can be diluted before use by purchasing the adhesive emulsion with high concentration and corresponding adhesive. The main function of the surfactant is that the binder is uniformly dispersed in water and is removed in the subsequent sintering process. In the mixing process of the step, sand milling can be adopted, in a specific embodiment, the mixing treatment is adopted by adopting a mode of twice sand milling and ultrasonic treatment, the first grinding is carried out for 1-3 hours under the condition of 2000-2500 rpm, the second grinding is carried out for 1-2 hours under the condition of 1000-1500 rpm, and finally ultrasonic dispersion is carried out. The solid content of the microporous layer slurry obtained by the process is 8-30%.
And S3, coating the microporous layer slurry on the surface of the substrate layer, and drying and sintering to form the microporous layer to obtain the gas diffusion layer.
Wherein, the coating comprises a spraying method, a brushing method, a knife coating method, a silk screen method and the like. The coating speed is 40-60 mm/min, preferably 50mm/min; the thickness of the coating is 40 μm to 80. Mu.m, preferably 50. Mu.m. Wherein the temperature in the drying process is 50-90 ℃ and the time is 1-2 h. The sintering treatment is carried out in an inert atmosphere, the sintering temperature is 200-380 ℃, and the sintering time is 0.5-2 h. It should be understood that the specific temperature and time of the sintering process may be adjusted depending on the material of the surfactant in the binder emulsion.
The raw materials adopted in the preparation method of the gas diffusion layer are cheap and easy to obtain, the process is simple, the conditions in each process are mild, the environment is friendly, and the preparation method is suitable for industrial production and application.
In yet another embodiment, the present invention provides the use of the gas diffusion layer described above in the manufacture of a fuel cell.
In another embodiment, the present invention provides a membrane electrode assembly including a first gas diffusion layer, a first catalytic layer, a proton exchange membrane, a second catalytic layer, and a second gas diffusion layer stacked in this order. Wherein the first gas diffusion layer and/or the second gas diffusion layer are/is the gas diffusion layers. Wherein the microporous layer in the gas diffusion layer is attached to the catalytic layer.
In a specific example, the proton exchange membrane is a polymer membrane doped with phosphoric acid, including but not limited to a polybenzimidazole membrane doped with phosphoric acid (PBI membrane), a polyvinylpyrrolidone membrane doped with phosphoric acid (PVP membrane), etc., and the catalyst in the first and second catalytic layers includes but is not limited to Pt/C, ir/C, ag/C, ru/C.
In another embodiment, the invention provides a fuel cell, which comprises the membrane electrode assembly and bipolar plates arranged on two sides of the membrane electrode assembly.
Still another embodiment of the present invention provides an electric device including the above-described fuel cell. Such power utilization devices include, but are not limited to, devices involved in the fields of stationary generators, transportation equipment, portable power sources, and the like. Including but not limited to passenger cars, commercial cars, bicycles, motorcycles, aircraft, watercraft, and the like.
The invention is described in detail below in connection with specific embodiments, which are intended to be illustrative rather than limiting.
Example 1
Addition of metal oxide Al 2 O 3 Is prepared by the following steps:
s1, adding 400mL of isopropanol and 45mL of ultrapure water into a sand mill, adding 50g of XC-72 carbon black, and starting the sand mill to grind for 2 hours at 2200rpm after the addition is finished to obtain carbon powder treatment liquid.
S2, continuously adding 125g of PTFE emulsion with 10wt% of binder and 3g of Al into the sand mill containing the carbon powder treatment liquid 2 O 3 And (3) starting the sand mill again to grind for 2 hours at 2500rpm, reducing the rotation speed of the sand mill to 1200rpm, grinding for 1.5 hours, taking out the sanded mixed solution, and performing ice bath ultrasonic dispersion for 1 hour to obtain the microporous layer slurry.
And S3, coating the microporous layer slurry on the surface of the carbon fiber substrate layer by using a slit coating mode, wherein the coating speed is 50mm/min, the height is 50 mu m, the temperature of an operating table is 60 ℃, and the microporous layer slurry is continuously dried on the operating table for 1h after the coating is finished. And (3) placing the dried sample into a tube furnace, and sintering at 360 ℃ for 1.5 hours under a nitrogen atmosphere to obtain the gas diffusion layer.
Example 2
Addition of metal oxide Fe 2 O 3 Is prepared by the following steps:
s1, adding 400mL of ethylene glycol and 45mL of ultrapure water into a sand mill, adding 50g of XC-72 carbon black, and starting the sand mill to grind for 1h at 2000rpm after the addition is finished to obtain carbon powder treatment liquid.
S2, continuously adding 125g of EEP emulsion with 10wt% of binder content and 3g of Fe into the sand mill containing the carbon powder treatment liquid 2 O 3 And (3) starting the sand mill again to grind for 1h at 2000rpm, reducing the rotation speed of the sand mill to 1500rpm, grinding for 2h again, taking out the sanded mixed solution, and performing ice bath ultrasonic dispersion for 2h to obtain the microporous layer slurry.
And S3, coating the microporous layer slurry on the surface of the carbon fiber substrate layer by using a slit coating mode, wherein the coating speed is 50mm/min, the height is 50 mu m, the temperature of an operating table is 80 ℃, and the microporous layer slurry is continuously dried on the operating table for 1h after the coating is finished. And (3) placing the dried sample into a tube furnace, and sintering at 300 ℃ for 1.5 hours under a nitrogen atmosphere to obtain the gas diffusion layer.
Example 3
Addition of metal oxide MnO 2 Is prepared by the following steps:
s1, adding 400mL of methanol and 45mL of ultrapure water into a sand mill, adding 50g of XC-72 carbon black, and starting the sand mill to grind at 2200rpm for 1.5h after the addition to obtain carbon powder treatment liquid.
S2, continuously adding 125g of PFA emulsion with 10wt% binder content and 3g of MnO into the sand mill containing the carbon powder treatment liquid 2 And (3) starting the sand mill again to grind for 3 hours at 2000rpm, reducing the rotation speed of the sand mill to 1000rpm, grinding for 1 hour again, taking out the sanded mixed solution, and performing ice bath ultrasonic dispersion for 1 hour to obtain the microporous layer slurry.
And S3, coating the microporous layer slurry on the surface of the carbon fiber substrate layer by using a slit coating mode, wherein the coating speed is 50mm/min, the height is 50 mu m, the temperature of an operating table is 50 ℃, and the microporous layer slurry is continuously dried on the operating table for 1h after the coating is finished. And (3) placing the dried sample into a tube furnace, and sintering at 340 ℃ for 0.5h under a nitrogen atmosphere to obtain the gas diffusion layer.
Example 4
Preparing a gas diffusion layer added with a metal oxide MgO:
s1, adding 400mL of ethanol and 45mL of ultrapure water into a sand mill, adding 50g of XC-72 carbon black, and starting the sand mill to grind at 2300rpm for 1.5 hours after the addition to obtain carbon powder treatment liquid.
And S2, continuously adding 125g of PFA emulsion with the binder content of 10wt% and 3g of MgO powder into the sand mill containing the carbon powder treatment liquid, starting the sand mill again to grind for 3 hours at 2100rpm, then reducing the rotation speed of the sand mill to 1200rpm, grinding for 1 hour again, taking out the sanded mixed liquid, and performing ice bath ultrasonic dispersion for 1.5 hours to obtain microporous layer slurry.
And S3, coating the microporous layer slurry on the surface of the carbon fiber substrate layer by using a slit coating mode, wherein the coating speed is 50mm/min, the height is 50 mu m, the temperature of an operating table is 50 ℃, and the microporous layer slurry is continuously dried on the operating table for 1h after the coating is finished. And (3) placing the dried sample into a tube furnace, and sintering at 340 ℃ for 1.5 hours in a nitrogen atmosphere to obtain the gas diffusion layer.
Example 5
Addition of metal oxide Al 2 O 3 Is prepared by the following steps:
s1, adding 400mL of isopropanol and 100mL of ultrapure water into a sand mill, adding 50g of XC-72 carbon black, and starting the sand mill to grind for 2 hours at 2200rpm after the addition is finished to obtain carbon powder treatment liquid.
S2, continuously adding 150g of PTFE emulsion with 10wt% of binder and 3g of Al into the sand mill containing the carbon powder treatment liquid 2 O 3 And (3) starting the sand mill again to grind for 2 hours at 2500rpm, reducing the rotation speed of the sand mill to 1200rpm, grinding for 1.5 hours, taking out the sanded mixed solution, and performing ice bath ultrasonic dispersion for 1 hour to obtain the microporous layer slurry.
And S3, coating the microporous layer slurry on the surface of the carbon fiber substrate layer by using a slit coating mode, wherein the coating speed is 50mm/min, the height is 50 mu m, the temperature of an operating table is 60 ℃, and the microporous layer slurry is continuously dried on the operating table for 1h after the coating is finished. And (3) placing the dried sample into a tube furnace, and sintering at 360 ℃ for 1.5 hours under a nitrogen atmosphere to obtain the gas diffusion layer.
Example 6
Addition of metal oxide Al 2 O 3 Is prepared by the following steps:
s1, adding 400mL of isopropanol and 150mL of ultrapure water into a sand mill, adding 50g of XC-72 carbon black, and starting the sand mill to grind for 2 hours at 2200rpm after the addition is finished to obtain carbon powder treatment liquid.
S2, continuously adding 80g of PTFE emulsion with 10wt% of binder and 3g of Al into the sand mill containing the carbon powder treatment liquid 2 O 3 And (3) starting the sand mill again to grind for 2 hours at 2500rpm, reducing the rotation speed of the sand mill to 1200rpm, grinding for 1.5 hours, taking out the sanded mixed solution, and performing ice bath ultrasonic dispersion for 1 hour to obtain the microporous layer slurry.
And S3, coating the microporous layer slurry on the surface of the carbon fiber substrate layer by using a slit coating mode, wherein the coating speed is 50mm/min, the height is 50 mu m, the temperature of an operating table is 60 ℃, and the microporous layer slurry is continuously dried on the operating table for 1h after the coating is finished. And (3) placing the dried sample into a tube furnace, and sintering at 360 ℃ for 1.5 hours under a nitrogen atmosphere to obtain the gas diffusion layer.
Example 7
Addition of metal oxide Al 2 O 3 Is prepared by the following steps:
s1, adding 400mL of isopropanol and 45mL of ultrapure water into a sand mill, adding 50g of XC-72 carbon black, and starting the sand mill to grind for 2 hours at 2200rpm after the addition is finished to obtain carbon powder treatment liquid.
S2, continuously adding 125g of PTFE emulsion with 10wt% of binder and 2g of Al into the sand mill containing the carbon powder treatment liquid 2 O 3 And (3) starting the sand mill again to grind for 2 hours at 2500rpm, reducing the rotation speed of the sand mill to 1200rpm, grinding for 1.5 hours, taking out the sanded mixed solution, and performing ice bath ultrasonic dispersion for 1 hour to obtain the microporous layer slurry.
And S3, coating the microporous layer slurry on the surface of the carbon fiber substrate layer by using a slit coating mode, wherein the coating speed is 50mm/min, the height is 50 mu m, the temperature of an operating table is 60 ℃, and the microporous layer slurry is continuously dried on the operating table for 1h after the coating is finished. And (3) placing the dried sample into a tube furnace, and sintering at 360 ℃ for 1.5 hours under a nitrogen atmosphere to obtain the gas diffusion layer.
Example 8
Addition of metal oxide Al 2 O 3 Is prepared by the following steps:
s1, adding 400mL of isopropanol and 45mL of ultrapure water into a sand mill, adding 50g of XC-72 carbon black, and starting the sand mill to grind for 2 hours at 2200rpm after the addition is finished to obtain carbon powder treatment liquid.
S2, continuously adding 125g of PTFE emulsion with 10wt% of binder and 2.5g of Al into the sand mill containing the carbon powder treatment liquid 2 O 3 Starting the sand mill again to grind for 2h at 2500rpm, then reducing the rotation speed of the sand mill to 1200rpm for further grinding for 1.5h, taking out the sanded mixed solution for ice bathAnd (5) performing ultrasonic dispersion for 1h to obtain microporous layer slurry.
And S3, coating the microporous layer slurry on the surface of the carbon fiber substrate layer by using a slit coating mode, wherein the coating speed is 50mm/min, the height is 50 mu m, the temperature of an operating table is 60 ℃, and the microporous layer slurry is continuously dried on the operating table for 1h after the coating is finished. And (3) placing the dried sample into a tube furnace, and sintering at 360 ℃ for 1.5 hours under a nitrogen atmosphere to obtain the gas diffusion layer.
Example 9
Addition of metal oxide Al 2 O 3 Is prepared by the following steps:
s1, adding 400mL of isopropanol and 45mL of ultrapure water into a sand mill, adding 50g of XC-72 carbon black, and starting the sand mill to grind for 2 hours at 2200rpm after the addition is finished to obtain carbon powder treatment liquid.
S2, continuously adding 125g of PTFE emulsion with 10wt% of binder and 4g of Al into the sand mill containing the carbon powder treatment liquid 2 O 3 And (3) starting the sand mill again to grind for 2 hours at 2500rpm, reducing the rotation speed of the sand mill to 1200rpm, grinding for 1.5 hours, taking out the sanded mixed solution, and performing ice bath ultrasonic dispersion for 1 hour to obtain the microporous layer slurry.
And S3, coating the microporous layer slurry on the surface of the carbon fiber substrate layer by using a slit coating mode, wherein the coating speed is 50mm/min, the height is 50 mu m, the temperature of an operating table is 60 ℃, and the microporous layer slurry is continuously dried on the operating table for 1h after the coating is finished. And (3) placing the dried sample into a tube furnace, and sintering at 360 ℃ for 1.5 hours under a nitrogen atmosphere to obtain the gas diffusion layer.
Example 10
Addition of metal oxide Al 2 O 3 Is prepared by the following steps:
s1, adding 400mL of isopropanol and 45mL of ultrapure water into a sand mill, adding 50g of XC-72 carbon black, and starting the sand mill to grind for 2 hours at 2200rpm after the addition is finished to obtain carbon powder treatment liquid.
S2, continuously adding 125g of PTFE emulsion with 10wt% of binder and 5g of Al into the sand mill containing the carbon powder treatment liquid 2 O 3 The powder was ground for 2 hours at 2500rpm by restarting the sand mill, and then the rotational speed of the sand mill was reduced to 1200rpm for further 1.5 hoursTaking out the sanded mixed solution, and performing ice bath ultrasonic dispersion for 1h to obtain microporous layer slurry.
And S3, coating the microporous layer slurry on the surface of the carbon fiber substrate layer by using a slit coating mode, wherein the coating speed is 50mm/min, the height is 50 mu m, the temperature of an operating table is 60 ℃, and the microporous layer slurry is continuously dried on the operating table for 1h after the coating is finished. And (3) placing the dried sample into a tube furnace, and sintering at 360 ℃ for 1.5 hours under a nitrogen atmosphere to obtain the gas diffusion layer.
Example 11
Addition of metal oxide Al 2 O 3 Is prepared by gas diffusion layer
S1, adding 400ml of isopropanol and 45ml of ultrapure water into a sand mill, adding 50g of XC-72 carbon black, and starting the sand mill to grind for 2 hours at 2200rpm after the addition is finished to obtain carbon powder treatment liquid.
S2, continuously adding 125g of PTFE emulsion with 10wt% of binder and 8g of Al into the sand mill containing the carbon powder treatment liquid 2 O 3 And (3) starting the sand mill again to grind for 2 hours at 2500rpm, reducing the rotation speed of the sand mill to 1200rpm, grinding for 1.5 hours, taking out the sanded mixed solution, and performing ice bath ultrasonic dispersion for 1 hour to obtain the microporous layer slurry.
And S3, coating the microporous layer slurry on the surface of the carbon fiber substrate layer by using a slit coating mode, wherein the coating speed is 50mm/min, the height is 50 mu m, the temperature of an operating table is 60 ℃, and the microporous layer slurry is continuously dried on the operating table for 1h after the coating is finished. And (3) placing the dried sample into a tube furnace, and sintering at 360 ℃ for 1.5 hours under a nitrogen atmosphere to obtain the gas diffusion layer.
Example 12
Addition of metal oxide Al 2 O 3 Is prepared by the following steps:
s1, adding 400ml of isopropanol and 45ml of ultrapure water into a sand mill, adding 50g of XC-72 carbon black, and starting the sand mill to grind for 2 hours at 2200rpm after the addition is finished to obtain carbon powder treatment liquid.
S2, continuously adding 250g of PTFE emulsion with 10wt% of binder and 3g of Al into the sand mill containing the carbon powder treatment liquid 2 O 3 The powder was ground for 2 hours at 2500rpm by restarting the sand mill and then fallingAnd (3) grinding for 1.5 hours again at the rotating speed of the low-sand mill of 1200rpm, taking out the sanded mixed solution, and performing ice bath ultrasonic dispersion for 1 hour to obtain microporous layer slurry.
And S3, coating the microporous layer slurry on the surface of the carbon fiber substrate layer by using a slit coating mode, wherein the coating speed is 50mm/min, the height is 50 mu m, the temperature of an operating table is 60 ℃, and the microporous layer slurry is continuously dried on the operating table for 1h after the coating is finished. And (3) placing the dried sample into a tube furnace, and sintering at 360 ℃ for 1.5 hours under a nitrogen atmosphere to obtain the gas diffusion layer.
Comparative example 1
Preparation of a gas diffusion layer without addition of metal oxide:
s1, adding 400ml of isopropanol and 45ml of ultrapure water into a sand mill, adding 50g of XC-72 carbon black, and starting the sand mill to grind for 2 hours at 2200rpm after the addition is finished to obtain carbon powder treatment liquid.
And S2, continuously adding 125g of PTFE emulsion with the binder content of 10wt% into the sand mill containing the carbon powder treatment liquid, starting the sand mill again to grind for 2 hours at 2500rpm, then reducing the rotation speed of the sand mill to 1200rpm and grinding for 1.5 hours, taking out the sanded mixed liquid, and performing ice bath ultrasonic dispersion for 1 hour to obtain the microporous layer slurry.
And S3, coating the microporous layer slurry on the surface of the carbon fiber substrate layer by using a slit coating mode, wherein the coating speed is 50mm/min, the height is 50 mu m, the temperature of an operating table is 60 ℃, and the microporous layer slurry is continuously dried on the operating table for 1h after the coating is finished. And (3) placing the dried sample into a tube furnace, and sintering at 360 ℃ for 1.5 hours under a nitrogen atmosphere to obtain the gas diffusion layer.
Comparative example 2
This comparative example is substantially the same as example 1, except that the metal oxide is changed to CaO.
The raw materials and proportions of examples 1 to 12 and comparative examples 1 to 2 are shown in Table 1.
Table 1 raw materials and proportions of each example and comparative example
The gas diffusion layer samples obtained in examples 1 to 12 and comparative examples 1 to 2 were subjected to an experiment of phosphoric acid corrosion in which 50% of phosphoric acid was used, the soaking time was 100 hours, and the temperature was 20 ℃. The thickness, air permeability, electrical resistance, and tensile strength of each gas diffusion layer sample were measured before and after the phosphoric acid corrosion test. The specific results are shown in Table 2.
TABLE 2 phosphoric acid Corrosion test results for each gas diffusion layer of examples and comparative examples
From comparison of the performance parameters before and after immersing phosphoric acid in each example and comparative example in table 2, it can be obtained that the increase of the resistance of the metal oxide doped gas diffusion layer before and after immersing is small, while the increase of the resistance of the gas diffusion layer without adding metal oxide is large, wherein the increase of the resistance after immersing the gas diffusion layer in example 1 is only 0.02mΩ@1mpa, and the increase of the resistance corresponding to the gas diffusion layer in comparative example 1 is 0.2mΩ@1mpa, which is different by one order of magnitude. Meanwhile, the change of the tensile strength of the gas diffusion layer doped with the metal oxide after the phosphoric acid soaking is much smaller than that of the gas diffusion layer undoped with the metal oxide, wherein the tensile strength of the gas diffusion layer of example 1 after the soaking is reduced by about 2N/cm, and the tensile strength of the gas diffusion layer of comparative example 1 is reduced by about 20N/cm. In the fuel cell, the electric resistance of the gas diffusion layer is increased to weaken the electric conductivity, and the tensile strength is weakened to easily cause mechanical damage, so that the service life of the fuel cell is shortened. In addition, when the metal oxide is doped in a proper ratio (comparative example 1 and example 11), it can not only ensure the gas permeability and conductivity of the gas diffusion layer, but also minimize the phosphoric acid corrosion according to various performance parameters before and after the soaking thereof. The metal oxide of comparative example 2 was CaO, and the increase in the resistance of the CaO-added gas diffusion layer after the phosphoric acid soaking was still significantly improved, which suggests that not all metal oxides may have a good phosphoric acid corrosion resistance, which may occur due to the fact that CaO reacts too slowly with phosphoric acid at the operating temperature of the fuel cell.
Fuel cell test was performed using the gas diffusion layer samples obtained in examples 1 to 12 and comparative examples 1 to 2 as cathode and anode gas diffusion layers of HT-PEMFC, and the effective area of the membrane electrode was 5×5cm 2 The platinum loading of noble metal of the cathode and anode catalytic layers is 1mg/cm 2 The high temperature proton exchange membrane is a PBI membrane doped with phosphoric acid, the running temperature of the battery is 200 ℃, and no back pressure exists. In order to accelerate the aging of the membrane electrode, triangular wave circulation of 0.6-1.0V is used for 1000 circles, the sweeping speed is 100mV/s, and the performance curves of the membrane electrode before and after the accelerated aging are recorded. The current densities at 0.6V before and after the aging test are shown in Table 3. The polarization curves before and after aging of examples 1, 2 and comparative example 1 are shown in fig. 1 to 3.
TABLE 3 peak power densities (mW/cm) before and after aging for each gas diffusion layer of examples and comparative examples 2 )
According to the current densities of 0.6V before and after the aging test of each example and comparative example in table 3, it is known that the current density of the fuel cell before and after aging tends to decrease more remarkably compared with the current density of the fuel cell corresponding to the gas diffusion layer doped with the specific metal oxide, i.e., the fuel cell corresponding to the gas diffusion layer doped with the metal oxide can slow down the degradation of the cell performance and prolong the service life of the fuel cell. In addition, according to examples 11 and 12, when the doped metal oxide or the binder is excessive, the resistance value thereof is increased, resulting in poor initial electrical properties of the corresponding fuel cell, which cannot meet the basic requirements of the fuel cell.
From fig. 1 to 3, it is understood that comparative example 1 shows a significant deterioration in performance after the aging test, which is related to erosion of phosphoric acid in the membrane electrode. When the metal oxide is added, the metal oxide Al is doped 2 O 3 The corresponding fuel cell of the gas diffusion layer of (a) has a lower degree of degradation of cell performance than that of a fuel cell without the addition of metal oxide Al 2 O 3 Is provided. In combination with the relevant test results of table 2, it can be derived that: the doped metal oxide can effectively relieve the corrosion of phosphoric acid to the gas diffusion layer, slow down the performance attenuation of the cell and prolong the service life of the fuel cell.
The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described 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 above 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 invention. 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, wherein the gas diffusion layer comprises a substrate layer and a microporous layer disposed on the substrate layer, and wherein the microporous layer comprises the following components: carbon powder, a binder and a metal oxide.
2. The gas diffusion layer according to claim 1, wherein the microporous layer comprises at least one of the following (1) to (3):
(1) The microporous layer comprises the following components in parts by weight: 60-85 parts of carbon powder, 10-30 parts of binder and 1-10 parts of metal oxide;
(2) The microporous layer comprises the following components in percentage by mass: 60-85% of carbon powder, 10-30% of binder and 1-10% of metal oxide;
(3) The microporous layer comprises the following components in percentage by mass: 70-80% of carbon powder, 15-25% of binder and 3-8% of metal oxide.
3. The gas diffusion layer according to any one of claims 1 to 2, wherein the metal oxide comprises at least one of the following features (4) to (6):
(4) The metal oxide can react with phosphoric acid at 160-220 ℃ to generate phosphate;
(5) The metal oxide is selected from Fe 2 O 3 、Al 2 O 3 、MnO 2 And one or more of MgO;
(6) The particle size of the metal oxide is 40 nm-100 nm.
4. The gas diffusion layer according to any one of claims 1 to 2, characterized in that the gas diffusion layer comprises at least one of the following (7) to (11):
(7) The carbon powder is one or more of XC-72, XC-72R, ketjen black, carbon nano tubes, graphene and graphite;
(8) The particle size of the carbon powder is 30 nm-500 nm;
(9) The adhesive is one or more of polytetrafluoroethylene, perfluoroethylene propylene copolymer, tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer and polysilazane resin;
(10) The thickness of the basal layer is 150-200 mu m;
(11) The thickness of the microporous layer is 20-50 mu m.
5. The method for producing a gas diffusion layer according to any one of claims 1 to 4, comprising:
s1, mixing carbon powder with alcohol and water to obtain carbon powder treatment liquid;
s2, mixing the carbon powder treatment liquid with a binder and a metal oxide to obtain microporous layer slurry;
and S3, coating the microporous layer slurry on the surface of the substrate layer, and drying and sintering to form the microporous layer to obtain the gas diffusion layer.
6. The method of producing a gas diffusion layer according to claim 5, characterized in that the production method comprises at least one of the following features (12) to (16):
(12) The volume ratio of the alcohol to the water is 1:0.1-1;
(13) The alcohol is one or more of methanol, n-propanol, isopropanol, ethylene glycol and n-butanol;
(14) The binder is added in the form of a binder emulsion, and the components of the binder emulsion comprise: the adhesive comprises an adhesive, a surfactant and water, wherein the adhesive accounts for 10-20% of the mass of the adhesive emulsion;
(15) The solid content of the microporous layer slurry is 8% -30%;
(16) The sintering treatment is carried out in an inert atmosphere, the sintering temperature is 200-380 ℃, and the sintering time is 0.5-2 h.
7. Use of a gas diffusion layer according to any one of claims 1 to 4 for the preparation of a fuel cell.
8. A membrane electrode assembly comprising a first gas diffusion layer, a first catalytic layer, a proton exchange membrane, a second catalytic layer and a second gas diffusion layer laminated in sequence, wherein the first gas diffusion layer and/or the second gas diffusion layer is the gas diffusion layer of any one of claims 1 to 4, and the proton exchange membrane is a polymer membrane doped with phosphoric acid.
9. A fuel cell comprising the membrane electrode assembly of claim 8 and bipolar plates disposed on either side of the membrane electrode assembly.
10. An electrical device comprising the fuel cell of claim 9.
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