CN117926293A - Alkaline membrane electrode electrolyzer for producing hydrogen by alkaline water electrolysis and preparation method thereof - Google Patents

Abstract

The invention provides an alkaline membrane electrode type electrolytic tank for producing hydrogen by alkaline water electrolysis and a preparation method thereof. The alkaline membrane electrode type electrolytic cell comprises an electrolytic unit and end plates arranged on two sides of the electrolytic unit, the electrolytic unit comprises an electrolytic cell, and the electrolytic cell comprises a bipolar plate, an anode diffusion layer, a membrane electrode, a cathode diffusion layer and a bipolar plate which are stacked in sequence; the membrane electrode comprises a diaphragm, and an anode catalyst layer and a cathode catalyst layer which are respectively supported on the two side surfaces of the diaphragm; the membrane is a porous membrane or an alkaline anion exchange membrane; the thickness of the bipolar plate is 1-3mm, the thicknesses of the anode diffusion layer and the cathode diffusion layer are respectively 0.02-4mm, and the mesh numbers of the anode diffusion layer and the cathode diffusion layer are respectively 50-500 meshes.

Description

Alkaline membrane electrode electrolyzer for producing hydrogen by alkaline water electrolysis and preparation method thereof

Technical Field

The invention relates to the technical field of hydrogen production by alkaline water electrolysis, and in particular to an alkaline membrane electrode electrolyzer for hydrogen production by alkaline water electrolysis and a preparation method thereof.

Background Art

With the increasing global attention to environmental protection and decarbonization and the advancement of renewable energy power generation technology, the use of renewable energy such as wind power, photovoltaic and hydropower to produce hydrogen is an important way to achieve a green hydrogen economy. Hydrogen energy can be widely used in methanol production, oil hydrogenation, synthetic ammonia, metal smelting, heating and vehicle transportation. The total amount of renewable energy is growing significantly and will become one of the main energy sources. Its power generation cost is declining with the maturity of technology and the expansion of scale. Renewable energy hydrogen production is expected to be competitive in the market. In addition, renewable energy hydrogen production can absorb abandoned wind, photovoltaic and hydropower electricity to obtain low-cost hydrogen.

Water electrolysis hydrogen production technology includes alkaline water electrolysis hydrogen production, proton exchange membrane water electrolysis hydrogen production, anion exchange membrane water electrolysis hydrogen production and solid oxide water electrolysis hydrogen production. Among them, alkaline water electrolysis hydrogen production technology is the most mature and has been widely used in thermal power plants and precision electronic product production. The schematic diagram of the electrolysis chamber structure of the traditional alkaline electrolyzer is shown in Figure 4, which includes bipolar plates, anode nickel mesh electrodes, diaphragms, cathode nickel mesh electrodes, and bipolar plates stacked in sequence, and the nickel mesh electrodes used are shown in Figure 5. Alkaline water electrolysis hydrogen production technology has the advantages of low equipment cost, long life and robustness, and is suitable for large-scale production of green hydrogen, but the existing alkaline water electrolysis hydrogen production electrolyzer still has the disadvantages of low current density and high electrolysis energy consumption. Reducing the chamber voltage of alkaline water electrolysis is the key to improving electrolysis energy efficiency and current density.

Patent application CN104364425A discloses a bipolar alkaline water electrolysis unit and an electrolyzer, wherein the bipolar alkaline water electrolysis unit provided is assembled in an electrolyzer for electrolyzing an electrolyte consisting of alkaline water to obtain oxygen and hydrogen, wherein the bipolar alkaline water electrolysis unit is provided with an anode for oxygen evolution, a cathode for hydrogen evolution, a conductive partition separating the anode and the cathode, and an annular outer frame surrounding the conductive partition, wherein a gas and electrolyte passage portion is provided at the upper portion of the conductive partition and/or the outer frame, and an electrolyte passage portion is provided at the lower portion of the conductive partition and/or the outer frame. This scheme, by providing an outer frame surrounding the partition of the bipolar alkaline water electrolysis unit, will not damage the ion permeable diaphragm or electrodes (anode and cathode) even if electrolysis is performed at a high current density of more than 3kA/ ^m2 , can be easily installed, and can also suppress equipment costs. The main improvement purpose of this scheme is to provide a bipolar alkaline water electrolysis unit and electrolyzer with low equipment cost and capable of stable electrolysis.

Summary of the invention

The invention provides an alkaline membrane electrode electrolyzer for producing hydrogen by alkaline water electrolysis and a preparation method thereof. The alkaline membrane electrode electrolyzer has a lower cell voltage in producing hydrogen by alkaline water electrolysis, which is beneficial to reducing the energy consumption of alkaline water electrolysis.

To achieve the purpose, the present invention provides the following technical solutions:

In one aspect, the present invention provides an alkaline membrane electrode electrolyzer for producing hydrogen by alkaline water electrolysis, the alkaline membrane electrode electrolyzer comprising an electrolysis unit and end plates arranged on both sides of the electrolysis unit, the electrolysis unit comprising an electrolysis chamber, the electrolysis chamber comprising a bipolar plate, an anode diffusion layer, a membrane electrode, a cathode diffusion layer and a bipolar plate stacked in sequence;

The membrane electrode comprises a diaphragm and an anode catalyst layer and a cathode catalyst layer respectively loaded on the two side surfaces of the diaphragm; the diaphragm is a porous diaphragm or an alkaline anion exchange membrane;

The thickness of the bipolar plate is 1-3 mm, the thickness of the anode diffusion layer and the cathode diffusion layer are 0.02-4 mm respectively, and the mesh numbers of the anode diffusion layer and the cathode diffusion layer are 50-500 meshes respectively.

Preferably, the thickness of the anode catalyst layer and the cathode catalyst layer is 2-50 μm, respectively, preferably ≥2 μm and less than 10 μm; further preferably, the ratio of the thickness of the anode catalyst layer to the cathode catalyst layer is 1-3.

In some embodiments, the material of the porous membrane is selected from one or more of polyethersulfone, polysulfone, polyphenylene sulfide, polytetrafluoroethylene, polyvinylidene fluoride, and polyvinyl chloride.

In some embodiments, the material of the alkaline anion exchange membrane is selected from quaternary ammonium salt anion exchange membrane, polyethersulfone anion exchange membrane or polyphenylene ether anion exchange membrane.

In some embodiments, the membrane has a porosity of 30-80% and a thickness of 0.05-0.7 mm.

Preferably, the bipolar plate is a nickel-plated steel plate or a titanium plate; preferably, the bipolar plate has a nickel-plated layer with a thickness of 1-200 μm.

Preferably, the anode diffusion layer and the cathode diffusion layer are respectively selected from nickel mesh, nickel felt, porous nickel plate, porous nickel foil, nickel-plated steel mesh, nickel-plated porous steel plate, nickel-plated titanium mesh or nickel-plated porous titanium plate.

Preferably, the catalysts in the anode catalyst layer and the cathode catalyst layer are selected from one or more of metals including nickel and metal oxides including nickel. Preferably, the catalyst loadings in the anode catalyst layer and the cathode catalyst layer are 0.5-20 mg/cm ² , respectively.

Preferably, the electrolysis unit comprises two or more electrolysis chambers.

Preferably, in the electrolysis chamber, among the bipolar plates, anode diffusion layers, membrane electrodes, cathode diffusion layers and bipolar plates stacked in sequence, sealing gaskets are provided between two adjacent components.

Preferably, the thickness of the bipolar plate is 2-3 mm, the thickness of the anode diffusion layer and the cathode diffusion layer is 0.1-0.2 mm, and the mesh size of the anode diffusion layer and the cathode diffusion layer is 150-250 meshes.

The present invention also provides a method for preparing the alkaline membrane electrode type electrolyzer described above, wherein the end plates are respectively arranged on both sides of the electrolysis unit and assembled to obtain the alkaline membrane electrode type electrolyzer.

In some embodiments, the preparation steps of the membrane electrode in the electrolysis unit include: respectively loading an anode catalyst layer and a cathode catalyst layer on both side surfaces of the diaphragm by physical vapor deposition, transfer or direct coating to obtain the membrane electrode.

In some embodiments, the transfer method includes the following operations: coating a catalyst slurry in which a catalyst is dispersed on a transfer membrane, and then drying it; and then placing it on both sides of the diaphragm to obtain the membrane electrode by transfer.

In some embodiments, the direct coating method includes the following operations: coating a catalyst slurry dispersed with a catalyst on both sides of the diaphragm, and obtaining the membrane electrode by drying and hot pressing; preferably, the drying is carried out at 80-150°C, and the hot pressing is carried out at 130-210°C and 0.5MPa-10MPa.

In some embodiments, in the catalyst slurry, the binder used is selected from one or more of polysulfone, polyethersulfone, polyphenylene sulfide and perfluorosulfonic acid resin;

Preferably, in the catalyst slurry, the solvent used is selected from one or more of esters, ketones, amides, alcohols and water solvents;

Further preferably, the mass ratio of catalyst:binder:solvent in the catalyst slurry is 1:0.01-5:0.4-50.

The technical solution provided by the present invention has the following beneficial effects:

The present invention is based on a membrane electrode with cathode and anode catalyst layers loaded on both sides of a porous diaphragm or an alkaline anion exchange membrane, and develops an electrolyzer for producing hydrogen by alkaline electrolysis of water. The electrolyzer is assembled with bipolar plates of a specific thickness and cathode and anode diffusion layers of a specific thickness and mesh size. It has a lower cell voltage when used in alkaline electrolysis of water to produce hydrogen, and can significantly reduce the energy consumption of alkaline electrolysis of water.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic structural diagram of an alkaline membrane electrode electrolyzer for producing hydrogen by alkaline water electrolysis provided in one embodiment of the present invention;

FIG2 is a photograph of the appearance of a membrane electrode in one embodiment of the present invention;

FIG3 is a schematic diagram of a partial structure of a membrane electrode in one embodiment of the present invention;

FIG4 is a schematic diagram of the electrolysis chamber structure of a conventional alkaline electrolytic cell;

FIG. 5 is a schematic diagram of a nickel mesh electrode used in a conventional alkaline electrolytic cell.

DETAILED DESCRIPTION

In order to facilitate the understanding of the present invention, the present invention will be further described below in conjunction with examples. It should be understood that the following examples are only for a better understanding of the present invention and do not mean that the present invention is limited to the following examples.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the invention belongs. The term "and/or" as may be used herein includes any and all combinations of one or more of the associated listed items.

Where specific experimental steps or conditions are not specified in the examples, the corresponding conventional experimental steps or conditions in the art can be used. The reagents or instruments used without specifying the manufacturer are all conventional products that can be purchased commercially.

The present invention provides an alkaline membrane electrode electrolyzer for producing hydrogen by alkaline water electrolysis, and its structure is basically the same as that of the existing electrolyzer, and the difference mainly lies in the improvement of the electrolysis chamber. The partial structural schematic diagram of the electrolyzer of the present invention is shown in Figure 1. Specifically, the alkaline membrane electrode electrolyzer includes an electrolysis unit and end plates arranged on both sides of the electrolysis unit, and the electrolysis unit includes an electrolysis chamber, and the electrolysis chamber includes a bipolar plate, an anode diffusion layer, a membrane electrode, a cathode diffusion layer and a bipolar plate stacked in sequence. Among them, the membrane electrode includes a diaphragm and an anode catalyst layer and a cathode catalyst layer respectively loaded on the surfaces of both sides of the diaphragm, as shown in Figures 2 and 3; the diaphragm is a porous diaphragm or an alkaline anion exchange membrane; the membrane electrode is an integrated structure of "anode catalyst layer-diaphragm-cathode catalyst layer". Among them, the thickness of the bipolar plate is 1-3mm, the thickness of the anode diffusion layer and the cathode diffusion layer is 0.02-4mm, and the mesh number of the anode diffusion layer and the cathode diffusion layer is 50-500 mesh respectively.

The present invention develops an alkaline membrane electrode type electrolyzer for producing hydrogen by alkaline water electrolysis based on a specific membrane electrode. The specific membrane electrode uses a porous diaphragm or an alkaline anion exchange membrane as a diaphragm, and an anode catalyst layer and a cathode catalyst layer are respectively loaded on the surfaces of both sides of the diaphragm. Based on the specific membrane electrode, an electrolysis chamber is assembled with a bipolar plate, an anode diffusion layer and a cathode diffusion layer, and then an electrolyzer is assembled. The thickness of the bipolar plate is controlled to be 1-3 mm, the thickness of the anode diffusion layer and the cathode diffusion layer are controlled to be 0.02-4 mm, and the mesh numbers of the anode diffusion layer and the cathode diffusion layer are controlled to be 50-500 meshes. The obtained electrolyzer exhibits a lower chamber voltage when used in producing hydrogen by alkaline water electrolysis.

In some preferred embodiments, the thickness of the anode catalyst layer and the cathode catalyst layer is 2-50 μm, respectively. The use of catalyst layers in this thickness range is beneficial to improving the application performance of the electrolyzer in alkaline water electrolysis to produce hydrogen; more preferably, the thickness of the anode catalyst layer and the cathode catalyst layer are ≥2 μm and less than 10 μm, respectively. The inventors have found that in the electrolyzer of the present invention, the use of catalyst layers in this preferred thickness range can provide a sufficient number of catalytic active sites, while reducing the distance between the anode and the cathode, which is beneficial to further reduce the voltage of the electrolysis chamber; further preferably, the ratio of the thickness of the anode catalyst layer to the cathode catalyst layer is 1-3, which is beneficial to further improve the performance of the electrolyzer in alkaline water electrolysis.

In the alkaline membrane electrode electrolyzer provided in the present invention, the diaphragm in the membrane electrode used is a porous diaphragm or an alkaline anion exchange membrane. Preferably, the material of the porous diaphragm is selected from one or more of polyethersulfone, polysulfone, polyphenylene sulfide, polytetrafluoroethylene, polyvinylidene fluoride, and polyvinyl chloride; preferably, the material of the alkaline anion exchange membrane is selected from quaternary ammonium salt anion exchange membrane, polyethersulfone anion exchange membrane or polyphenylene ether anion exchange membrane.

In some preferred embodiments, in the alkaline membrane electrode electrolyzer provided by the present invention, the porosity of the diaphragm in the membrane electrode used is 30-80%, and the thickness is 0.05-0.7 mm. In the electrolyzer of the present invention, there is no need for the diaphragm to be too thick, and the obtained electrolyzer has better performance in the alkaline electrolysis of water to produce hydrogen, which is beneficial to reducing the chamber voltage.

In some preferred embodiments, the bipolar plate is a nickel-plated steel plate or titanium plate; preferably, the bipolar plate has a nickel-plated layer with a thickness of 1-200 μm; the use of the preferred nickel-plated bipolar plate is beneficial to improving the application stability of the electrolyzer in alkaline water electrolysis to produce hydrogen.

In some preferred embodiments, the anode diffusion layer and the cathode diffusion layer are respectively selected from nickel mesh, nickel felt, perforated nickel plate, perforated nickel foil, nickel-plated steel mesh, nickel-plated perforated steel plate, nickel-plated titanium mesh or nickel-plated perforated titanium plate. The preferred anode diffusion layer and cathode diffusion layer are used to improve the application stability of the electrolyzer in the electrolysis of water to produce hydrogen. There is no particular restriction on the hole shape of the anode diffusion layer and the cathode diffusion layer, for example, it can be any shape such as circular, rhombus, square, rectangular or irregular.

In the present invention, the catalysts used in the anode catalyst layer and the cathode catalyst layer of the membrane electrode can be catalyst types conventionally applicable in the art. For example, the anode catalyst layer can use a conventionally used oxygen evolution catalyst with oxygen evolution activity, and the cathode catalyst layer can use a conventionally used hydrogen evolution catalyst with hydrogen evolution activity. There is no particular limitation on this. Preferably, the catalysts in the anode catalyst layer and the cathode catalyst layer are respectively selected from metals including nickel and/or metal oxides including nickel. The nickel-based catalyst can have higher hydrogen evolution or oxygen evolution performance in an alkaline environment and has good stability. As needed, the catalyst may also contain other metal elements, which are selected from one or more of Group IIB, Group IVB, Group VB, Group VIB, Group VIIB, Group VIII, Group IVA and rare earth elements. For example, the Group IIB element is selected from Zn, and/or the Group IVB element is selected from Ti and/or Zr, and/or the Group VB element is selected from V, and/or the Group VIB element is selected from one or more of Cr, Mo and W, and/or the Group VIIB element is selected from Mn, and/or the Group VIII element is selected from Fe and/or Co, and/or the Group IVA is selected from Sn, and/or the rare earth element is selected from Ce and/or La. In some embodiments, the other metal elements are one or more of Mo, W, Mn, Fe, Co, Zn, Ce and La. In some embodiments, in the nickel-based catalyst used in the anode catalyst layer and the cathode catalyst layer, the mass ratio of the other metal elements to the nickel element is independently 0-20:1. In some specific embodiments, as an example, the nickel-based catalyst is, for example, but not limited to, nickel-iron spinel, nickel-iron hydrotalcite, nickel-cobalt catalyst, nickel-molybdenum catalyst, iron-cobalt-nickel catalyst, Raney nickel catalyst, etc.

Preferably, the catalyst loading in the anode catalyst layer and the cathode catalyst layer is 0.5-20 mg/cm ² respectively. The preferred catalyst loading is conducive to providing a sufficient number of catalytic active sites, and the relatively small catalyst layer thickness is conducive to reducing the distance between the anode and the cathode and reducing the voltage of the electrolysis chamber.

In some embodiments, the electrolysis unit of the electrolytic cell includes more than two electrolysis chambers, for example, two or more electrolysis chambers are repeatedly stacked, and the bipolar plates between two adjacent electrolysis chambers can be shared.

In a specific embodiment, in each electrolysis chamber, a sealing gasket is provided between two adjacent components among the bipolar plate, the anode diffusion layer, the membrane electrode, the cathode diffusion layer and the bipolar plate.

In some more preferred embodiments, in the alkaline membrane electrode electrolyzer of the present invention, the thickness of the bipolar plate is 2-3 mm, the thickness of the anode diffusion layer and the cathode diffusion layer is 0.1-0.2 mm, and the mesh size of the anode diffusion layer and the cathode diffusion layer is 150-250 mesh respectively; the inventors found that the adoption of this preferred embodiment is conducive to further significantly reducing the cell voltage of the electrolyzer provided by the present invention in alkaline water electrolysis to produce hydrogen.

The present invention also provides a method for preparing the alkaline membrane electrode electrolyzer described above, which specifically includes: providing end plates on both sides of the electrolysis unit, fixing them with the end plates, and assembling to obtain the alkaline membrane electrode electrolyzer; the specific assembly operations are conventional in the art, and those skilled in the art can use conventional assembly operations in the art to assemble the electrolyzer of the present invention, which will not be described in detail.

In some embodiments, the preparation steps of the membrane electrode in the electrolysis unit include: forming an anode catalyst layer and a cathode catalyst layer on both side surfaces of the diaphragm by physical vapor deposition, transfer or direct coating to obtain the membrane electrode.

Regarding the physical vapor deposition method, its specific operation can refer to the corresponding conventional process operation in the art, for example, vacuum evaporation, sputtering coating, arc plasma plating, ion plating and molecular beam epitaxy or magnetron sputtering can be specifically used to load the corresponding catalyst on the two side surfaces of the diaphragm. Preferably, the magnetron sputtering method is used, for example, the following steps may be included: the catalyst is prepared into a target material, argon gas is filled under vacuum conditions, and the argon gas is glow discharged under high pressure to form argon ions, and the argon ions are accelerated to bombard the target material under the action of the electric field force to sputter the target material, and the target material is deposited on the porous diaphragm according to the load ratio. The catalyst layer formed by the magnetron sputtering method has a high catalyst dispersion, which is conducive to further reducing the overpotential of the electrolysis of water, and forming a strong and non-detachable catalyst layer, which ultimately helps to improve the application stability of the electrolyzer in the production of hydrogen by alkaline electrolysis of water.

In some embodiments, the transfer method includes the following operations: coating a catalyst slurry in which a catalyst is dispersed on a transfer film, and then drying; placing it on both sides of the diaphragm, and obtaining a membrane electrode by transfer. The transfer film is, for example, but not limited to, one of PET, PTFE or PI. Drying is, for example, vacuum drying, and the drying temperature is, for example, 80-150°C. Transfer conditions include, for example, a transfer temperature of 110-230°C and a pressure of 0.5MPa-10MPa.

In some embodiments, the direct coating method includes the following operations: coating a catalyst slurry dispersed with a catalyst on both sides of the diaphragm, drying, and hot pressing to obtain the membrane electrode; preferably, the drying is carried out at 80-150°C, and the hot pressing is carried out at 130-210°C and 0.5MPa-10MPa.

In the above transfer method and direct coating method, in the catalyst slurry involved, the binder used is preferably selected from one or more of polysulfone, polyethersulfone, polyphenylene sulfide and perfluorosulfonic acid resin. In the catalyst slurry, the solvent used is preferably selected from one or more of esters, ketones, amides, alcohols and water solvents; in some preferred embodiments, the solvent is one or more of butyl ester, butyrolactone, valerolactone, acetone, butanone, cyclohexanone, dimethylformamide, dimethylacetamide, propanol, isopropanol, ethanol and water. In some preferred embodiments, the mass ratio of catalyst: binder: solvent in the catalyst slurry is 1: 0.01-5: 0.4-50, preferably 1: 0.02-3: 1-5. The preparation of the catalyst slurry may specifically include the following operations: the catalyst, binder and solvent are made into a slurry by stirring or ultrasonic dispersion.

In the above transfer method and direct coating method, there is no particular limitation on the coating method involved, and conventional coating methods in the art can be used, such as spraying, blade coating, roll-to-roll coating, or slit coating to uniformly coat the slurry on the transfer film or directly on the diaphragm.

The schematic diagram of the structure of the electrolytic chamber in the electrolytic cell of the following embodiments is shown in FIG1 (where the sealing gasket is not shown), and the structure of the membrane electrode used is shown in FIG3. The structures of the electrolytic cell and the membrane electrode not specifically explained below can be referred to the previous description and will not be described one by one.

The following describes some of the raw materials used in the following examples or comparative examples:

NiFe ₂ O ₄ : Beijing Dekedaojin Technology Co., Ltd.;

NiZnFe ₂ O ₄ : Beijing Dekedaojin Technology Co., Ltd.;

NiCo ₂ O ₄ : Beijing Dekedaojin Technology Co., Ltd.;

Raney nickel catalyst: Jiangsu Raney Metal Technology Co., Ltd.;

Iron-cobalt-nickel alloy: Beijing Dekedaojin Technology Co., Ltd.;

Polysulfone composite polymer porous membrane: Agfa zirfon 220;

Polyethersulfone composite polymer porous membrane: Beijing Maiborui Biomembrane Technology Co., Ltd.

Electrolytic cell performance test: The electrolytic cells of the following embodiments or comparative examples are installed on the water electrolysis test platform. The test conditions include: the reaction medium is 30wt% KOH aqueous solution; the reaction temperature is 80°C, the reaction pressure is normal pressure, and the cell voltage of the electrolytic cell is tested at current densities of 0.4A/ ^cm2 and 0.8A/ ^cm2 .

Embodiment 1:

In the electrolytic unit of the electrolytic cell of this embodiment, an electrolytic chamber is assembled in the order of bipolar plate-sealing gasket-anode diffusion layer-sealing gasket-membrane electrode-sealing gasket-cathode diffusion layer-sealing gasket-bipolar plate, and the electrolytic unit includes a plurality of such electrolytic chambers; end plates are placed and fixed on both sides of the electrolytic unit to assemble into an electrolytic cell.

Among them, the thickness of the bipolar plate is 2mm, and the bipolar plate adopts a steel plate with a nickel-plated layer of 80μm thickness; the anode diffusion layer and the cathode diffusion layer both adopt nickel mesh diffusion layers with a thickness of 0.3mm and a mesh number of 100 respectively.

The catalyst in the anode catalyst layer of the membrane electrode is NiFe ₂ O ₄ , the thickness of the anode catalyst layer is 50 μm, and the catalyst loading of the anode catalyst layer is 2.5 mg/cm ² . The catalyst in the cathode catalyst layer of the membrane electrode is Raney nickel catalyst, the thickness of the cathode catalyst layer is 25 μm, and the catalyst loading of the cathode catalyst layer is 2.5 mg/cm ² . The membrane electrode diaphragm adopts a polysulfone composite polymer porous diaphragm, the thickness of the diaphragm is 0.22 mm, and the porosity is 60%.

In this embodiment, the steps of preparing the membrane electrode include:

1) stirring the anode catalyst, the binder and the solvent in a mass ratio of 1:0.12:4 to obtain an anode catalyst slurry; stirring the cathode catalyst, the binder and the solvent in a mass ratio of 1:0.03:1 to obtain a cathode catalyst slurry; wherein the binder is polysulfone and the solvent is a ketone solution (a mixed solution of 50wt% cyclohexanone, 40wt% butanone and 10wt% butyrolactone);

The anode catalyst slurry and cathode catalyst slurry were respectively coated on the surfaces of both sides of the diaphragm, then dried at 120°C for 2 hours, and then placed in a hot press for hot pressing at a temperature of 150°C and a pressure of 5 MPa for 5 minutes to form an anode catalyst layer and a cathode catalyst layer on the surfaces of both sides of the diaphragm to obtain a membrane electrode.

The cell voltage of the electrolytic cell of this embodiment was tested at current densities of 0.4 A/cm ² and 0.8 A/cm ^2. The results are shown in Table 1.

Embodiment 2:

In the electrolytic unit of the electrolytic cell of this embodiment, an electrolytic chamber is assembled in the order of bipolar plate-sealing gasket-anode diffusion layer-sealing gasket-membrane electrode-sealing gasket-cathode diffusion layer-sealing gasket-bipolar plate, and the electrolytic unit includes a plurality of such electrolytic chambers; end plates are placed and fixed on both sides of the electrolytic unit to assemble into an electrolytic cell.

Among them, the thickness of the bipolar plate is 3mm, and the bipolar plate adopts a titanium plate with a 50μm thick nickel-plated layer; the anode diffusion layer and the cathode diffusion layer both adopt nickel mesh diffusion layers with a thickness of 0.15mm and a mesh number of 200 respectively.

The catalyst in the anode catalyst layer of the membrane electrode is NiZnFe ₂ O ₄ , the thickness of the anode catalyst layer is 30 μm, and the catalyst loading of the anode catalyst layer is 1.5 mg/cm ² . The catalyst in the cathode catalyst layer of the membrane electrode is an iron-cobalt-nickel alloy, the thickness of the cathode catalyst layer is 10 μm, and the catalyst loading of the cathode catalyst layer is 1 mg/cm ² . The membrane electrode diaphragm adopts a polyethersulfone composite polymer porous diaphragm, the thickness of the diaphragm is 0.25 mm, and the porosity is 70%.

In this embodiment, the steps of preparing the membrane electrode include:

1) stirring the anode catalyst, the binder and the solvent in a mass ratio of 1:0.2:2 to obtain an anode catalyst slurry; stirring the cathode catalyst, the binder and the solvent in a mass ratio of 1:0.2:1.5 to obtain a cathode catalyst slurry; wherein the binder is a perfluorosulfonic acid resin and the solvent is an isopropanol aqueous solution with a concentration of 25wt%;

The anode catalyst slurry and cathode catalyst slurry were respectively coated on the surfaces of both sides of the diaphragm, and then dried at 80°C for 12 hours. Then, they were placed in a hot press and hot-pressed at a temperature of 130°C and a pressure of 3 MPa for 10 minutes to form an anode catalyst layer and a cathode catalyst layer on the surfaces of both sides of the diaphragm to obtain a membrane electrode.

The cell voltage of the electrolytic cell of this embodiment was tested at current densities of 0.4 A/cm ² and 0.8 A/cm ^2. The results are shown in Table 1.

Embodiment 3:

In the electrolytic unit of the electrolytic cell of this embodiment, an electrolytic chamber is assembled in the order of bipolar plate-sealing gasket-anode diffusion layer-sealing gasket-membrane electrode-sealing gasket-cathode diffusion layer-sealing gasket-bipolar plate, and the electrolytic unit includes a plurality of such electrolytic chambers; end plates are placed and fixed on both sides of the electrolytic unit to assemble into an electrolytic cell.

Among them, the thickness of the bipolar plate is 2mm, and the bipolar plate adopts a steel plate with a 120μm thick nickel-plated layer; the anode diffusion layer and the cathode diffusion layer both adopt nickel mesh diffusion layers with a thickness of 0.09mm and a mesh number of 300 respectively.

The catalyst in the anode catalyst layer of the membrane electrode is NiFe ₂ O ₄ , the thickness of the anode catalyst layer is 20 μm, and the catalyst loading of the anode catalyst layer is 1 mg/cm ² . The catalyst in the cathode catalyst layer of the membrane electrode is Raney nickel catalyst, the thickness of the cathode catalyst layer is 10 μm, and the catalyst loading of the cathode catalyst layer is 1 mg/cm ² . The membrane electrode diaphragm adopts a polysulfone composite polymer porous diaphragm, the thickness of the diaphragm is 0.22 mm, and the porosity is 60%.

In this embodiment, the steps of preparing the membrane electrode include:

1) The anode catalyst, the binder and the solvent are stirred evenly in a mass ratio of 1:0.075:1.5 to obtain an anode catalyst slurry; the cathode catalyst, the binder and the solvent are stirred evenly in a mass ratio of 1:0.09:1.8 to obtain a cathode catalyst slurry; wherein the binder is polyethersulfone, and the solvent is a ketone solution (a mixed solution of 50wt% cyclohexanone, 20wt% butanone, and 30wt% butyrolactone);

The anode catalyst slurry and cathode catalyst slurry were respectively coated on the transfer film (PTFE), and then dried at 100°C. The transfer film loaded with the catalyst was then placed on both sides of the diaphragm and hot-pressed on a hot press device to obtain a membrane electrode, wherein the transfer temperature was 180°C and the pressure was 10MPa.

The cell voltage of the electrolytic cell of this embodiment was tested at current densities of 0.4 A/cm ² and 0.8 A/cm ^2. The results are shown in Table 1.

Embodiment 4:

In the electrolytic unit of the electrolytic cell of this embodiment, an electrolytic chamber is assembled in the order of bipolar plate-sealing gasket-anode diffusion layer-sealing gasket-membrane electrode-sealing gasket-cathode diffusion layer-sealing gasket-bipolar plate, and the electrolytic unit includes a plurality of such electrolytic chambers; end plates are placed and fixed on both sides of the electrolytic unit to assemble into an electrolytic cell.

Among them, the thickness of the bipolar plate is 1mm, and the bipolar plate adopts a steel plate with a 20μm thick nickel-plated layer; the anode diffusion layer and the cathode diffusion layer both adopt nickel mesh diffusion layers, with a thickness of 0.05mm and a mesh number of 400 respectively.

The catalyst in the anode catalyst layer of the membrane electrode is NiCo ₂ O ₄ , the thickness of the anode catalyst layer is 25 μm, and the catalyst loading of the anode catalyst layer is 1.3 mg/cm ² . The catalyst in the cathode catalyst layer of the membrane electrode is Raney nickel catalyst, the thickness of the cathode catalyst layer is 15 μm, and the catalyst loading of the cathode catalyst layer is 1.5 mg/cm ² . The membrane electrode diaphragm adopts a polysulfone composite polymer porous diaphragm, the thickness of the diaphragm is 0.22 mm, and the porosity is 60%.

In this embodiment, the steps of preparing the membrane electrode include:

1) The anode catalyst, the binder and the solvent are stirred evenly in a mass ratio of 1:0.27:1.8 to obtain an anode catalyst slurry; the cathode catalyst, the binder and the solvent are stirred evenly in a mass ratio of 1:0.3:2 to obtain a cathode catalyst slurry; wherein the binder is a perfluorosulfonic acid resin and the solvent is a 40wt% n-propanol aqueous solution;

The anode catalyst slurry and cathode catalyst slurry were respectively coated on the surfaces of both sides of the diaphragm, and then dried at 150°C for 0.5h, and then placed in a hot press for hot pressing at a temperature of 160°C and a pressure of 2MPa for 3min to form an anode catalyst layer and a cathode catalyst layer on the surfaces of both sides of the diaphragm to obtain a membrane electrode.

The cell voltage of the electrolytic cell of this embodiment was tested at current densities of 0.4 A/cm ² and 0.8 A/cm ^2. The results are shown in Table 1.

Example 5

This embodiment is carried out with reference to the embodiment 1, except that the thickness of the anode diffusion layer and the cathode diffusion layer is 3 mm, and the mesh size is 80 mesh respectively.

The cell voltage of the electrolytic cell of this embodiment was tested at current densities of 0.4 A/cm ² and 0.8 A/cm ^2. The results are shown in Table 1.

Example 6

The method is carried out with reference to Example 2, except that the thickness of the anode catalyst layer and the cathode catalyst layer are both less than 10 μm, and the thickness of the anode catalyst layer is 5 μm, and the thickness of the cathode catalyst layer is 2 μm.

The cell voltage of the electrolytic cell of this embodiment was tested at current densities of 0.4A/ ^cm2 and 0.8A/ ^cm2 . The results are shown in Table 1.

Example 7

The method is carried out with reference to Example 2, except that the thickness of the anode catalyst layer and the cathode catalyst layer are both less than 10 μm, and the thickness of the anode catalyst layer is 9 μm, and the thickness of the cathode catalyst layer is 5 μm.

The cell voltage of the electrolytic cell of this embodiment was tested at current densities of 0.4 A/cm ² and 0.8 A/cm ^2. The results are shown in Table 1.

Comparative Example 1:

The difference between the electrolytic cell in this comparative example and Example 1 is that the structure of the electrolytic chamber is different, and the electrolytic chamber includes a bipolar plate, an anode electrode, a diaphragm, a cathode electrode and a bipolar plate stacked in sequence. The thickness of the bipolar plate is 2 mm, and the material of the bipolar plate is a steel plate with a nickel plating layer of 80 μm thick. The anode electrode and the cathode electrode are electrodes commonly used in commercial alkaline electrolytic cells, with a thickness of 0.5 mm, respectively, and the anode electrode is a nickel mesh, and the cathode electrode is a nickel mesh sprayed with Ni-Al alloy. The cathode electrode is soaked in a 10wt% NaOH aqueous solution for 24 hours before use, and washed with deionized water until the solution is neutral. The diaphragm is a polyphenylene sulfide non-woven fabric (thickness 1 mm) commonly used in commercial alkaline electrolytic cells. The bipolar plate, non-woven fabric, anode electrode and cathode electrode are assembled into an electrolytic cell, and the cell voltage at current densities of 0.4A/ ^cm2 and 0.8A/ ^cm2 is tested.

Comparative Example 2:

The difference between the electrolytic cell in this comparative example and Example 1 is that the structure of the electrolytic cell is different, and the electrolytic cell includes a bipolar plate, an anode electrode, a diaphragm, a cathode electrode and a bipolar plate stacked in sequence. The thickness of the bipolar plate is 2 mm, and the material of the bipolar plate is a steel plate with a nickel plating layer of 80 μm thick. The anode electrode and the cathode electrode are electrodes commonly used in commercial alkaline electrolytic cells, with a thickness of 0.5 mm, respectively, and the anode electrode is a nickel mesh, and the cathode electrode is a nickel mesh sprayed with Ni-Al alloy. The cathode electrode is soaked in a 10wt% NaOH aqueous solution for 24 hours before use, and washed with deionized water until the solution is neutral. The diaphragm is a polysulfone composite polymer porous diaphragm (thickness 0.22 mm), and the bipolar plate, the composite polymer porous diaphragm, the anode electrode and the cathode electrode are assembled into an electrolytic cell, and the cell voltage at current densities of 0.4A/ ^cm2 and 0.8A/ ^cm2 is tested.

Comparative Example 3

This comparative example was carried out with reference to Example 1, except that the thickness of the bipolar plate was 10 mm, the thickness of the anode diffusion layer and the cathode diffusion layer were 5 mm, and the mesh size was 40 meshes.

The cell voltage of the electrolytic cell of this embodiment was tested at current densities of 0.4 A/cm ² and 0.8 A/cm ^2. The results are shown in Table 1.

Comparative Example 4

This comparative example was carried out with reference to Example 1, except that the thickness of the bipolar plate was 0.8 mm, the thickness of the anode diffusion layer and the cathode diffusion layer were 0.015 mm, and the mesh size was 600 meshes.

The cell voltage of the electrolytic cell of this embodiment was tested at current densities of 0.4 A/cm ² and 0.8 A/cm ^2. The results are shown in Table 1.

Comparative Example 5

This comparative example is carried out with reference to Example 1, except that the thickness of the bipolar plate is 0.8 mm, the thickness of the anode diffusion layer and the cathode diffusion layer are 0.015 mm, and the mesh size is 40 meshes.

The cell voltage of the electrolytic cell of this embodiment was tested at current densities of 0.4 A/cm ² and 0.8 A/cm ^2. The results are shown in Table 1.

Table 1

Table 2

As can be seen from the experimental results of Table 1 and Table 2, the electrolyzer of the embodiment of the present invention can obtain lower cell electrolysis than the existing alkaline water electrolysis hydrogen production electrolyzer in Comparative Examples 1 and 2, which is beneficial to reduce the energy consumption of alkaline water electrolysis. From the comparison of the experimental results of the electrolyzer of the embodiment of the present invention and Comparative Examples 3-5, it can be seen that in the electrolyzer of the present invention, while satisfying "the thickness of the bipolar plate is 1-3mm, the thickness of the anode diffusion layer and the cathode diffusion layer is 0.02-4mm respectively, and the mesh number of the anode diffusion layer and the cathode diffusion layer is 50-500 mesh respectively", the provided electrolyzer has better performance and can significantly reduce the cell voltage in alkaline water electrolysis hydrogen production. Further, by comparing Example 2 with Examples 6 and 7, it can be seen that the thickness of the anode catalyst layer and the cathode catalyst layer is preferably controlled to be ≥2μm and less than 10μm, which is beneficial to further reduce the cell voltage.

It is easy to understand that the above embodiments are only examples for clear explanation and do not mean that the present invention is limited thereto. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from this are still within the protection scope of the present invention.

Claims (10)

1. An alkaline membrane electrode electrolyzer for producing hydrogen by alkaline electrolysis of water, characterized in that the alkaline membrane electrode electrolyzer comprises an electrolysis unit and end plates arranged on both sides of the electrolysis unit, the electrolysis unit comprises an electrolysis chamber, and the electrolysis chamber comprises a bipolar plate, an anode diffusion layer, a membrane electrode, a cathode diffusion layer and a bipolar plate stacked in sequence; The membrane electrode comprises a diaphragm and an anode catalyst layer and a cathode catalyst layer respectively loaded on the two side surfaces of the diaphragm; the diaphragm is a porous diaphragm or an alkaline anion exchange membrane; The thickness of the bipolar plate is 1-3 mm, the thickness of the anode diffusion layer and the cathode diffusion layer are 0.02-4 mm respectively, and the mesh numbers of the anode diffusion layer and the cathode diffusion layer are 50-500 meshes respectively. 2. The alkaline membrane electrode electrolyzer according to claim 1, characterized in that the thickness of the anode catalyst layer and the cathode catalyst layer are 2-50 μm, preferably ≥2 μm and less than 10 μm; Further preferably, the thickness ratio of the anode catalyst layer to the cathode catalyst layer is 1-3. 3. The alkaline membrane electrode electrolyzer according to claim 1, characterized in that the material of the porous diaphragm is selected from one or more of polyethersulfone, polysulfone, polyphenylene sulfide, polytetrafluoroethylene, polyvinylidene fluoride, and polyvinyl chloride; And/or, the material of the alkaline anion exchange membrane is selected from quaternary ammonium salt anion exchange membrane, polyethersulfone anion exchange membrane or polyphenylene ether anion exchange membrane; And/or, the diaphragm has a porosity of 30-80% and a thickness of 0.05-0.7 mm. 4. The alkaline membrane electrode electrolyzer according to any one of claims 1 to 3, characterized in that the bipolar plate is a nickel-plated steel plate or a titanium plate; preferably, the bipolar plate has a nickel-plated layer with a thickness of 1 to 200 μm; And/or, the anode diffusion layer and the cathode diffusion layer are respectively selected from nickel mesh, nickel felt, porous nickel plate, porous nickel foil, nickel-plated steel mesh, nickel-plated porous steel plate, nickel-plated titanium mesh or nickel-plated porous titanium plate. 5. The alkaline membrane electrode electrolyzer according to any one of claims 1 to 3, characterized in that the catalysts in the anode catalyst layer and the cathode catalyst layer are respectively selected from one or more of metals including nickel and metal oxides including nickel; Preferably, the catalyst loading in the anode catalyst layer and the cathode catalyst layer is 0.5-20 mg/cm ² , respectively. 6. The alkaline membrane electrode electrolyzer according to any one of claims 1 to 3, characterized in that the electrolysis unit comprises more than two electrolysis chambers; And/or, in the electrolysis chamber, among the bipolar plates, anode diffusion layers, membrane electrodes, cathode diffusion layers and bipolar plates stacked in sequence, sealing gaskets are provided between two adjacent components. 7. The alkaline membrane electrode electrolyzer according to any one of claims 1 to 3, characterized in that the thickness of the bipolar plate is 2-3 mm, the thickness of the anode diffusion layer and the cathode diffusion layer is 0.1-0.2 mm, and the mesh size of the anode diffusion layer and the cathode diffusion layer is 150-250 meshes. 8. The method for preparing an alkaline membrane electrode electrolyzer according to any one of claims 1 to 7, characterized in that the end plates are respectively arranged on both sides of the electrolysis unit and assembled to obtain the alkaline membrane electrode electrolyzer. 9. The preparation method according to claim 8 is characterized in that the preparation steps of the membrane electrode in the electrolysis unit include: respectively loading an anode catalyst layer and a cathode catalyst layer on the two side surfaces of the diaphragm by physical vapor deposition, transfer method or direct coating method to obtain the membrane electrode. 10. The preparation method according to claim 9, characterized in that the transfer method comprises the following operations: coating a catalyst slurry in which a catalyst is dispersed on a transfer film, and then drying it; placing it on both sides of the diaphragm, and obtaining the membrane electrode by transfer; And/or, the direct coating method comprises the following operations: coating a catalyst slurry containing a catalyst dispersed therein on both sides of the diaphragm, drying, and hot pressing to obtain the membrane electrode; preferably, the drying is performed at 80-150° C., and the hot pressing is performed at 130-210° C. and 0.5 MPa-10 MPa; Preferably, in the catalyst slurry, the binder used is selected from one or more of polysulfone, polyethersulfone, polyphenylene sulfide and perfluorosulfonic acid resin; Preferably, in the catalyst slurry, the solvent used is selected from one or more of esters, ketones, amides, alcohols and water solvents; Further preferably, the mass ratio of catalyst:binder:solvent in the catalyst slurry is 1:0.01-5:0.4-50.