AEM membrane electrode, AEM electrolyzer and electrolytic hydrogen production method

Abstract

The present invention discloses an AEM membrane electrode, an AEM electrolyzer and an electrolytic hydrogen production method, and belongs to the technical field of electrolytic hydrogen production. The AEM membrane electrode of the present invention is a vertical structure, which includes an anode collector mass transfer catalytic layer, an anion exchange membrane, a cathode catalytic layer and a cathode collector mass transfer layer from top to bottom; the AEM electrolyzer includes an anode end plate, a plurality of electrolysis chambers and a cathode end plate from top to bottom; each adjacent electrolysis chamber is isolated by a yin-yang composite plate; the anode surface of the yin-yang composite plate is connected to the alkali solution inlet and the alkali solution outlet, and the cathode surface of the yin-yang composite plate is connected to the hydrogen outlet; the electrolysis chamber includes an AEM membrane electrode, and its anode collector mass transfer catalytic layer contacts the anode surface of the yin-yang composite plate, and the cathode collector mass transfer layer contacts the cathode surface of the yin-yang composite plate. The membrane electrode of the present invention has better operating stability and more efficient hydrogen production performance, the electrolyzer has high gas production purity and high equipment safety, the water content of hydrogen is low, and the gas purification and drying cost is low.

Description

Technical Field

[0001] The present invention relates to the technical field of electrolytic hydrogen production, and in particular to an AEM membrane electrode, an AEM electrolyzer and an electrolytic hydrogen production method. Background Art

[0002] The information disclosed in the background of the invention is only intended to enhance the understanding of the overall background of the invention and should not be necessarily regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] Anion Exchange Membrane (AEM) water electrolysis hydrogen production technology uses anion exchange membrane as the diaphragm of the electrolytic cell to electrolyze water to generate hydrogen and oxygen. It is one of the most cutting-edge water electrolysis technologies. AEM electrolysis hydrogen production technology combines the advantages of traditional alkaline solution electrolysis hydrogen production (ALK) and pure water electrolysis hydrogen production (PEM), that is, it can use non-precious metal catalysts in an alkaline working environment, has low requirements for various components such as plates, and can be operated intermittently.

[0004] The electrochemical reaction in the AEM electrolyzer is similar to that in the ALK electrolyzer. The specific process is as follows:

[0005] Anode reaction: 4OH - →O2↑+H2O+2e - ;

[0006] Cathode reaction: 2H2O+2e - →H2↑+2OH - .

[0007] At present, the commercial AEM membrane electrode structure is mainly composed of a diffusion layer, a catalyst layer and an anion membrane. The diffusion layer is used for current collection and gas-liquid mass transfer, and the catalyst layer is the site of the electrochemical reaction. The preparation method of the catalyst layer is to deposit the electrocatalyst slurry directly on the diffusion layer, then sinter to form an electrode, and finally assemble it with the anion exchange membrane by mechanical or hot pressing (this method is called CCS method). The electrolyte used is a low-concentration alkali solution (KOH or NaOH solution with a mass fraction of 1-5%). The liquid inlet method is as follows: Figure 1As shown, this liquid inlet method is similar to the ALK electrolysis technology. The alkali solution enters the cathode chamber and the anode chamber respectively, and an electrochemical reaction occurs. The cathode chamber produces hydrogen and the anode chamber produces oxygen. Then, they enter the cathode tank and the anode tank respectively for gas-liquid separation. The hydrogen and oxygen enter the gas pipeline, and the remaining alkali solution is mixed and enters the electrolyzer. However, the problems with the above-mentioned commercial AEM electrolyzer are mainly the following aspects: First, since the diffusion layer and the catalytic layer in the membrane electrode are pressed together by physical action, there is a large contact resistance, and long-term operation will reduce the performance of the electrolyzer; second, the CCS method will lead to poor ion conduction between the electrode and the membrane, thereby increasing the interface resistance, which is not conducive to the stability of the membrane electrode; third, the double-circulation method has complex process operations, and the hydrogen produced at the cathode end has a high water content, which increases the cost of gas drying. In addition, the mixing of alkali solutions in the anode and cathode chambers leads to high oxygen content in hydrogen and hydrogen content in oxygen, thereby reducing the gas purity.

[0008] Therefore, it is necessary to develop an AEM membrane electrode with lower contact resistance and interface resistance and an AEM electrolyzer with high gas production purity. Summary of the invention

[0009] In view of this, the present invention provides an AEM membrane electrode, an AEM electrolyzer and a method for producing hydrogen by electrolysis, which solve the problems of poor long-term stability and low gas purity of the AEM electrolyzer in the prior art.

[0010] In a first aspect, the present invention provides an AEM membrane electrode, wherein the AEM membrane electrode is a vertical structure, and comprises, from top to bottom, an anode collector mass transfer catalyst layer, an anion exchange membrane, a cathode catalyst layer and a cathode collector mass transfer layer;

[0011] The anode collector mass transfer catalytic layer includes a nickel mesh, a nickel plain mesh and a porous nickel foil from top to bottom, and the nickel mesh, the nickel plain mesh and the porous nickel foil are welded and connected; an anode catalyst is attached to the surface of the porous nickel foil;

[0012] The cathode catalyst in the cathode catalyst layer is attached to the anion exchange membrane;

[0013] The cathode collector transfer layer includes nickel felt and nickel plain mesh in order from top to bottom, and the nickel felt and nickel plain mesh are welded and connected.

[0014] Preferably, the anode catalyst is selected from one or more of Ni, Fe, Co or Mn.

[0015] Preferably, the cathode catalyst is selected from one or more of Ni, Mo, Fe, Co, La or Ce.

[0016] Preferably, the welding process is diffusion welding.

[0017] In a second aspect, the present invention provides an AEM electrolytic cell, which comprises, from top to bottom, an anode terminal plate, a plurality of electrolytic chambers and a cathode terminal plate; each adjacent electrolytic chamber is isolated by a cathode-cathode composite plate;

[0018] The anode end plate is provided with an alkali solution inlet, an alkali solution outlet and a hydrogen outlet; the anode surface of the yin-yang composite plate is in communication with the alkali solution inlet and the alkali solution outlet, and the cathode surface of the yin-yang composite plate is in communication with the hydrogen outlet;

[0019] The electrolysis chamber comprises the AEM membrane electrode as described in the first aspect above, the anode collector mass transfer catalytic layer of the AEM membrane electrode contacts the anode surface of the yin-yang composite plate, and the cathode collector mass transfer layer of the AEM membrane electrode contacts the cathode surface of the yin-yang composite plate.

[0020] Preferably, a sealing gasket is also provided in the electrolysis chamber, and the sealing gasket is located on the upper and lower sides of the anion exchange membrane of the AEM membrane electrode.

[0021] Preferably, the anode surface of the anode end plate and the yin-yang composite plate is provided with a groove for accommodating the anode collector mass transfer catalytic layer of the AEM membrane electrode; the cathode end plate and the cathode surface of the yin-yang composite plate are provided with a groove for accommodating the cathode collector mass transfer layer of the AEM membrane electrode.

[0022] Preferably, the AEM electrolytic cell further comprises fastening bolts for pressing and fixing the anode end plate, the plurality of electrolysis chambers and the cathode end plate.

[0023] In a third aspect, the present invention further provides a method for producing hydrogen by electrolysis, based on the above-mentioned AEM electrolyzer, comprising the following steps:

[0024] After the AEM electrolytic cell is assembled, alkali solution is injected into each electrolytic cell through the alkali solution inlet, direct current is supplied to the AEM electrolytic cell, the anode end plate and the anode surface of the yin-yang composite plate are connected to the positive electrode of the power supply, and the cathode end plate and the cathode surface of the yin-yang composite plate are connected to the negative electrode of the power supply;

[0025] The alkali solution flowing through each electrolysis chamber is electrolyzed under the action of direct current, hydrogen is generated at the cathode end of the electrolysis chamber, and the hydrogen is discharged through the hydrogen outlet; oxygen is generated at the anode end of the electrolysis chamber, and oxygen and alkali solution are discharged through the alkali solution outlet.

[0026] Preferably, the voltage of the direct current is 1.8-2.0V.

[0027] Compared with the prior art, the present invention has achieved the following beneficial effects:

[0028] (1) The anode collector mass transfer catalytic layer and the cathode collector mass transfer layer of the AEM membrane electrode provided by the present invention are both connected by welding, and the contact resistance is lower; at the same time, the cathode catalyst of the present invention is attached to the anion exchange membrane, and the interface resistance between the anode and cathode is lower, so the membrane electrode of the present invention has better operating stability and more efficient hydrogen production performance;

[0029] (2) The structural design of the AEM electrolytic cell of the present invention allows the alkali solution to circulate only at the anode end, thereby preventing the mixing of the alkali solutions at the cathode and cathode ends. This not only simplifies the operation but also improves the purity of hydrogen and the safety of the equipment. The water content of hydrogen is low, thereby reducing the cost of gas purification and drying. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The drawings constituting part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their description are used to explain the present invention and do not constitute an improper limitation of the present invention. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0031] Figure 1 This is a schematic diagram of the liquid inlet method of the commercial AEM membrane electrode;

[0032] Figure 2 is a schematic diagram of the AEM membrane electrode structure provided by an embodiment of the present invention;

[0033] Figure 3 It is a schematic structural diagram of an AEM electrolytic cell provided in an embodiment of the present invention;

[0034] Figure 4 It is a schematic structural diagram of the anode surface and cathode surface of the yin-yang composite plate provided in an embodiment of the present invention;

[0035] Figure 5 is a schematic structural diagram of a sealing gasket provided by an embodiment of the present invention;

[0036] Figure 6 It is a schematic diagram of the decomposition structure of the electrolytic chamber of the AEM electrolytic cell provided in an embodiment of the present invention;

[0037] In the figure, 1, anode collector mass transfer catalytic layer; 101, nickel mesh; 102, anode nickel plain mesh; 103, porous nickel foil; 2, anion exchange membrane; 3, cathode catalytic layer; 4, cathode collector mass transfer layer; 401, nickel felt; 402, cathode nickel plain mesh; 5, anode terminal plate; 6, yin and yang composite plate; 601, anode surface; 602, first alkali solution through hole; 603, second alkali solution through hole; 604, first hydrogen through hole; 605, composite plate bolt hole; 606, cathode surface; 7, sealing gasket; 701, third alkali solution through hole; 702, fourth alkali solution through hole; 703, second hydrogen through hole; 704, gasket bolt hole; 8, cathode terminal plate; 9, alkali solution inlet; 10, alkali solution outlet; 11, hydrogen outlet; 12, fastening bolt; 13, base; 14, wiring copper busbar. DETAILED DESCRIPTION

[0038] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those of ordinary skill in the art to which the present invention belongs. In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0039] Please refer to Figure 2-6 , Figure 2 is a schematic diagram of the AEM membrane electrode structure provided by an embodiment of the present invention, Figure 3 is a schematic diagram of the structure of the AEM electrolytic cell provided in an embodiment of the present invention, Figure 4 Schematic diagram of the structure of the anode and cathode surfaces of the yin-yang composite plate provided in an embodiment of the present invention. Figure 5 is a schematic diagram of the structure of a sealing gasket provided in an embodiment of the present invention, Figure 6 It is a schematic diagram of the decomposition structure of the electrolytic chamber of the AEM electrolytic cell provided in an embodiment of the present invention.

[0040] The embodiment of the present invention provides an AEM membrane electrode, the AEM membrane electrode is a vertical structure, such as Figure 2 As shown, from top to bottom, it includes an anode collector mass transfer catalyst layer 1, an anion exchange membrane 2, a cathode catalyst layer 3 and a cathode collector mass transfer layer 4.

[0041] The anode collector mass transfer catalytic layer 1 includes a nickel mesh 101, an anode nickel plain mesh 102 and a porous nickel foil 103 from top to bottom, and an anode catalyst is attached to the surface of the porous nickel foil 103; the anode catalyst is selected from one or more of non-precious metals Ni, Fe, Co, and Mn. The nickel mesh 101 is a liquid guide layer, the anode nickel plain mesh 102 is a gas-liquid diffusion mass transfer layer, and the porous nickel foil 103 is an anode catalyst layer. The nickel mesh 101, the anode nickel plain mesh 102 and the porous nickel foil 103 are welded and connected, and the welding process is preferably diffusion welding, which can greatly reduce the contact resistance between the gas-liquid diffusion layer and the catalyst layer and improve the electrolysis efficiency. The temperature of the diffusion welding is 700-1500°C, the welding pressure is 10-30MPa, and the insulation time is 0.5-1h.

[0042] The thickness of the anode nickel plain mesh 102 is 0.5-1 mm, and the mesh number is 10-100 mesh; the thickness of the nickel stretched mesh 101 is 0.5-1 mm, and the mesh number is 10-100 mesh; the thickness of the porous nickel foil 103 is 0.1-0.3 mm, and the micropore diameter is 5-50 μm.

[0043] The cathode catalyst in the cathode catalyst layer 3 is attached to the anion exchange membrane 2. This design can reduce the interface resistance between the cathode and cathode, thereby improving the electrolysis efficiency. The cathode catalyst is selected from one or more of non-precious metals Ni, Mo, Fe, Co, La or Ce.

[0044] The cathode collector carrier layer 4 includes a nickel felt 401 and a cathode nickel plain mesh 402 from top to bottom. The nickel felt 401 is used as a current collecting layer, and its thickness is 0.2-0.5 mm and its porosity is 50-80%. The mesh number of the cathode nickel plain mesh 402 is 10-100 meshes and the thickness is 0.2-0.8 mm. The nickel felt 401 and the cathode nickel plain mesh 402 are welded and connected, and the welding process is diffusion welding, which can greatly reduce the contact resistance and improve the electrolysis efficiency. The temperature of the diffusion welding is 700-1500°C, the welding pressure is 10-30MPa, and the insulation time is 0.5-1h.

[0045] The present invention also provides an AEM electrolytic cell, which is a vertical structure, such as Figure 3 and Figure 6 As shown, the AEM electrolytic cell includes an anode terminal plate 5, a plurality of electrolytic chambers and a cathode terminal plate 8 from top to bottom; each adjacent electrolytic chamber is isolated by a cathode-cathode composite plate 6.

[0046] The anode end plate 5 is provided with an alkali solution inlet 9, an alkali solution outlet 10 and a hydrogen outlet 11. Figure 4As shown, the positive and negative composite plate 6 is provided with a first alkali solution through hole 602, a second alkali solution through hole 603, a first hydrogen through hole 604 and a composite plate bolt hole 605. The first alkali solution through hole 602 is communicated with the alkali solution inlet 9 of the anode end plate 5, the second alkali solution through hole 603 is communicated with the alkali solution outlet 10 of the anode end plate 5, and the first hydrogen through hole 604 is communicated with the hydrogen outlet 11 of the anode end plate 5.

[0047] The anode surface 601 of the yin-yang composite plate 6 is connected to the alkali solution inlet 9 and the alkali solution outlet 10 through the first alkali solution through hole 602 and the second alkali solution through hole 603, respectively, and the cathode surface 606 of the yin-yang composite plate 6 is connected to the hydrogen outlet 11 through the first hydrogen through hole 604. This structural design ensures that the alkali solution circulates only at the anode end of the electrolysis chamber, avoiding the mixing of the alkali solutions of the anode and cathode, and also ensures that the anode oxygen and the cathode hydrogen have high purity.

[0048] An AEM membrane electrode is arranged in each electrolysis chamber, and the anode collector mass transfer catalytic layer 1 of the AEM membrane electrode contacts the anode surface 601 of the yin-yang composite plate 6, and the cathode collector mass transfer layer 4 of the AEM membrane electrode contacts the cathode surface 606 of the yin-yang composite plate 6. In the uppermost electrolysis chamber of the AEM electrolyzer, the anode collector mass transfer catalytic layer 1 of the AEM membrane electrode contacts the anode terminal plate 5; in the lowermost electrolysis chamber of the AEM electrolyzer, the cathode collector mass transfer layer 4 of the AEM membrane electrode contacts the cathode terminal plate 8.

[0049] The electrolysis chamber is also provided with a sealing gasket 7, which is located on the upper and lower sides of the anion exchange membrane 2 of the AEM membrane electrode. Figure 5 As shown, the sealing gasket 7 is a frame-type structure, which is hollow inside and does not affect the mass transfer process, that is, does not affect the electrolysis reaction. The sealing gasket 7 can effectively fix the anion exchange membrane 2 and ensure that the electrolytic cell has good sealing performance.

[0050] The sealing gasket 7 is provided with a third alkali solution through hole 701, a fourth alkali solution through hole 702, a second hydrogen through hole 703 and a plurality of gasket bolt holes 704. The third alkali solution through hole 701 is communicated with the alkali solution inlet 9 of the anode end plate 5, the fourth alkali solution through hole 702 is communicated with the alkali solution outlet 10 of the anode end plate 5, and the second hydrogen through hole 703 is communicated with the hydrogen outlet 11 of the anode end plate 5.

[0051] To ensure the sealing of the electrolytic cell, the anode surface 601 of the yin-yang composite plate 6 and the anode end plate 5 are provided with grooves for accommodating the anode collector mass transfer catalytic layer 1 of the AEM membrane electrode; the cathode surface 606 of the yin-yang composite plate 6 and the cathode end plate 8 are provided with grooves for accommodating the cathode collector mass transfer layer 4 of the AEM membrane electrode.

[0052] The AEM electrolyzer is also provided with fastening bolts 12 for pressing and fixing the anode end plate 5, a plurality of electrolysis chambers and the cathode end plate 8; the fastening bolts 12 pass through the anode end plate 5, a plurality of composite plate bolt holes 605, the anion exchange membrane 2 and the gasket bolt holes 704, and the cathode end plate 8.

[0053] A base 13 is also provided at the bottom of the cathode end plate 8 of the AEM electrolytic cell to play a supporting role and ensure stability during electrolysis.

[0054] The AEM electrolytic cell is also provided with a copper busbar 14 for connecting to an electrolytic power source to provide direct current.

[0055] In order to ensure the stability of the electrolytic cell operation and avoid corrosion of the equipment under alkaline conditions, the material of the anode end plate 5, the cathode end plate 8 and the yin-yang composite plate 6 is selected from one or more of carbon steel nickel-plated, stainless steel or pure nickel.

[0056] The present invention also provides a method for producing hydrogen by electrolysis, based on the above-mentioned AEM electrolyzer, comprising the following steps:

[0057] After the AEM electrolytic cell is assembled, alkali solution is injected into each electrolytic cell through the alkali solution inlet 9, and direct current is passed through the AEM electrolytic cell, and the voltage of the direct current is 1.8-2.0 V. The anode end plate 5 and the anode surface 601 of the yin-yang composite plate 6 are connected to the positive pole of the power supply, and the cathode end plate 8 and the cathode surface 606 of the yin-yang composite plate 6 are connected to the negative pole of the power supply.

[0058] The alkali solution flowing through each electrolysis chamber is electrolyzed under the action of direct current, and hydrogen is generated at the cathode end of the electrolysis chamber, and the hydrogen is discharged through the hydrogen outlet 11; oxygen is generated at the anode end of the electrolysis chamber, and the oxygen and alkali solution are discharged through the alkali solution outlet 10.

[0059] The specific principle of hydrogen production by electrolysis is as follows: Figure 6 As shown, the alkali solution is injected into the anode end of each electrolytic chamber through the alkali solution inlet 9. Under the action of gravity, water molecules diffuse through the anode collector mass transfer catalyst layer 1 to the surface of the anion exchange membrane 2, and then penetrate from the anion exchange membrane 2 to the cathode catalyst layer 3. The water molecules undergo electrochemical reactions on the surface of the cathode catalyst layer 3 to produce H2 and OH - , H2 passes through the cathode collector carrier layer 4 through the second hydrogen through hole 703, and then leaves the electrolyzer through the first hydrogen through hole 604 and the hydrogen outlet 11; OH -The hydrogen is transferred to the anode catalyst layer (porous nickel foil 103) through the anion exchange membrane 2, and an electrochemical reaction occurs in the anode catalyst layer to generate O2. The generated O2 and the unreacted alkali solution leave the electrolyzer through the second alkali solution through hole 603 and the alkali solution outlet 10. The electrolytic hydrogen production method of the present invention only circulates the alkali solution at the anode end, and the mixing of the alkali solutions of the cathode and cathode is eliminated. It is not only simple to operate, but also improves the purity of hydrogen and the safety of the equipment; at the same time, since only a small amount of water will pass through the cathode collector mass transfer layer 4, the water content of the generated hydrogen is low.

[0060] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An AEM electrolytic cell, characterized in that: From top to bottom, it includes an anode terminal plate, a number of electrolytic chambers and a cathode terminal plate; each adjacent electrolytic chamber is isolated by a cathode-cathode composite plate; The anode end plate is provided with an alkali solution inlet, an alkali solution outlet and a hydrogen outlet; the anode surface of the yin-yang composite plate is in communication with the alkali solution inlet and the alkali solution outlet, and the cathode surface of the yin-yang composite plate is in communication with the hydrogen outlet; The electrolysis chamber comprises an AEM membrane electrode, the anode collector mass transfer catalytic layer of the AEM membrane electrode contacts the anode surface of the yin-yang composite plate, and the cathode collector mass transfer layer of the AEM membrane electrode contacts the cathode surface of the yin-yang composite plate; The AEM membrane electrode is a vertical structure, which includes, from top to bottom, an anode collector mass transfer catalyst layer, an anion exchange membrane, a cathode catalyst layer and a cathode collector mass transfer layer; The anode collector mass transfer catalytic layer includes a nickel mesh, a nickel plain mesh and a porous nickel foil from top to bottom, and the nickel mesh, the nickel plain mesh and the porous nickel foil are welded and connected; an anode catalyst is attached to the surface of the porous nickel foil; The cathode catalyst in the cathode catalyst layer is attached to the anion exchange membrane; The cathode collector transfer layer includes nickel felt and nickel plain mesh in order from top to bottom, and the nickel felt and nickel plain mesh are welded and connected; A sealing gasket is also provided in the electrolysis chamber, and the sealing gasket is located on the upper and lower sides of the anion exchange membrane of the AEM membrane electrode; The anode surface of the anode terminal plate and the yin-yang composite plate is provided with a groove for accommodating the anode collector mass transfer catalytic layer of the AEM membrane electrode; the cathode surface of the cathode terminal plate and the yin-yang composite plate is provided with a groove for accommodating the cathode collector mass transfer layer of the AEM membrane electrode.

2. The AEM electrolyzer according to claim 1, characterized in that The anode catalyst is selected from one or more of Ni, Fe, Co and Mn.

3. The AEM electrolyzer according to claim 1, characterized in that The cathode catalyst is selected from one or more of Ni, Mo, Fe, Co, La or Ce.

4. The AEM electrolyzer according to claim 1, characterized in that The welding process is diffusion welding.

5. The AEM electrolyzer according to claim 1, characterized in that The AEM electrolytic cell also includes fastening bolts for pressing and fixing the anode end plate, a plurality of electrolysis chambers and the cathode end plate.

6. A method for producing hydrogen by electrolysis, based on the AEM electrolyzer according to any one of claims 1 to 5, characterized in that: The steps include: After the AEM electrolytic cell is assembled, alkali solution is injected into each electrolytic cell through the alkali solution inlet, direct current is supplied to the AEM electrolytic cell, the anode end plate and the anode surface of the yin-yang composite plate are connected to the positive electrode of the power supply, and the cathode end plate and the cathode surface of the yin-yang composite plate are connected to the negative electrode of the power supply; The alkali solution flowing through each electrolysis chamber is electrolyzed under the action of direct current, hydrogen is generated at the cathode end of the electrolysis chamber, and the hydrogen is discharged through the hydrogen outlet; oxygen is generated at the anode end of the electrolysis chamber, and oxygen and alkali solution are discharged through the alkali solution outlet.

7. The method for producing hydrogen by electrolysis according to claim 6, characterized in that: The voltage of the direct current is 1.8-2.0V.

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