WO2022057551A1

WO2022057551A1 - Pem electrolytic cell conductive partition plate having gas-liquid distribution flow field structure

Info

Publication number: WO2022057551A1
Application number: PCT/CN2021/112980
Authority: WO
Inventors: 迟军; 俞红梅; 邵志刚; 孙凯; 韦世慧; 刘凯; 孙树成
Original assignee: 中国科学院大连化学物理研究所
Priority date: 2020-09-21
Filing date: 2021-08-17
Publication date: 2022-03-24

Abstract

The present invention relates to a PEM electrolytic cell conductive partition plate having a gas-liquid distribution flow field structure, and a processing method therefor. Sealant line grooves, a flow guide groove, a gas channel, a liquid channel and other functional partitions are integrated onto the same component and are integrally formed. Compared with a traditional conductive partition plate, the conductive partition plate in the present invention has the advantages of reducing the number of processing instances and the processing difficulty, such that the manufacturing of the conductive partition plate, the assembly quality of a pile and the positioning accuracy can all be guaranteed. In the conductive partition plate of the present invention, the sealant line grooves do not need to be reinforced separately, and the operation stability of an electrolytic cell under the working condition of generating high-pressure hydrogen (>3.5 MPa) can be guaranteed. Compared with the prior art, the conductive partition plate of the present invention has a simple structure and can be installed in an easy and reliable manner, processing flow links for the conductive partition plate are reduced, and the structural reliability thereof is improved.

Description

A conductive separator with gas-liquid distribution flow field structure for PEM electrolyzer

technical field

The invention belongs to the field of electrochemistry, and in particular relates to a conductive separator with a gas-liquid distribution flow field structure for a PEM electrolytic cell.

Background technique

The conductive separator is one of the core components of the electrolysis hydrogen production electrolyzer, which directly affects the electrolysis efficiency, electrolysis energy consumption, electrolysis cost and the life of the electrolysis cell.

The structure of the existing conductive separator for hydrogen production by water electrolysis is relatively complex, including multi-structure modules such as a main body, a plate-frame assembly, and a sealing structure. These structural modules are often machined individually as individual components. Such conductive separators have complex processing procedures and high positioning accuracy requirements, which bring a lot of inconvenience to the mass production and assembly of the conductive separators. In addition, as an independently processed plate-and-frame assembly, it needs to be connected to the main body of the conductive divider by bonding and welding. Such a connection method will cause problems such as weak connection method and excessive deformation of the flatness of the conductive divider, which is not conducive to The electrolytic cells operate under heated, high pressure operating conditions.

Specifically, the existing conductive separators for water electrolysis mainly have the following problems: 1. The plate and frame components of the conductive separators need to be processed separately, resulting in the need to repeat the same processing for the plate and frame components and the main body of the conductive separators, resulting in processing costs. Increase; 2. The position of the positioning hole of the conductive partition plate and the positioning hole of the main body of the conductive partition plate require high positioning accuracy, resulting in higher assembly difficulty; 3. The existing conductive partition plate sealant groove needs to be bonded , or welding for reinforcement, which complicates the processing process of the conductive separator, and cannot guarantee the reliability of the sealing function of the conductive separator under the high-voltage operation of the electrolytic cell; Fourth, in the stack of the filter press structure, There are many sealing interfaces in the equipment, and the risk of material leakage inside the stack is high. The conductive separators prepared by the existing conductive separator whole plate preparation process are mostly used for fuel cells, and are mostly in the form of stamping and molding. Stamping and molding will cause corresponding groove ridge structures on both sides of the entire board. The structure is not suitable for water electrolysis.

SUMMARY OF THE INVENTION

In view of the above problems, the present invention provides a conductive separator with a gas-liquid distribution flow field structure for a PEM electrolyzer, the conductive separator is a whole plate structure, and the conductive separator can be used for water electrolysis to produce hydrogen in the device.

The technical scheme of the present invention is as follows:

The invention provides a conductive partition plate with a gas-liquid distribution flow field structure for a PEM electrolytic cell. The conductive partition plate has a whole plate structure; one side of the conductive partition plate is provided with an anode flow field, and the other side is provided with an anode flow field. A cathode flow field is provided; both ends of the conductive separator are provided with an anode material inlet and outlet and a cathode material inlet and outlet.

Based on the above solution, preferably, each inlet and outlet and the periphery of the flow field are provided with sealant grooves.

Based on the above solution, preferably, a bridge area is provided between the anode material inlet and outlet and the anode flow field, for connecting the anode material inlet and outlet and the anode flow field.

Based on the above solution, preferably, four corners of the conductive partition plate are provided with positioning holes for fixing the conductive partition plate to the external structure.

Based on the above solution, preferably, the anode material inlets and outlets are located at both ends of the conductive separator in the width direction, and are centrally symmetric; the cathode material inlets and outlets are respectively located at two ends in the width direction of the conductive separator. end, and the center is symmetrical.

Based on the above solution, preferably, the anode material inlet and outlet and the cathode material inlet and outlet are rectangular.

Based on the above solution, preferably, the anode flow field is linear, the anode flow field includes several flow channels parallel to each other, and the cathode flow field is a plane region.

In the above-mentioned conductive partition plate, the plate-frame assembly is no longer separated from the main body of the conductive partition plate, but is integrally processed and formed as a part of the conductive partition plate.

The cathode/anode material inlet and outlet, positioning holes, bridge areas and the main body of the conductive separator in the plate-frame assembly are integrally formed, and it is no longer necessary to repeatedly process the same structure as the main body of the conductive separator.

The sealant wire groove is integrally formed with the main body of the conductive separator, and no additional connection method is required to fix the sealant wire groove to the main body of the conductive separator.

The above-mentioned conductive separator with gas-liquid distribution flow field structure for PEM electrolyzer can be processed and formed by a 3D printing method; the 3D printing method includes the following steps:

a. Three-dimensional modeling: make a three-dimensional model diagram of the conductive partition plate to be printed in a computer, and perform two-dimensional slice processing on the three-dimensional model diagram;

b. Preparation of printing materials;

c. Input the modeling graphics in step a into the 3D printing printing program according to the format; send the printing material prepared in step b into the printing device, and the printing nozzle in the printing device and the printing platform cooperate with each other, and the printing The materials are alternately printed and stacked to form, and after the printing is completed, a conductive separator with a whole board structure is obtained;

d. Send the conductive partition plate printed in step c out of the printing system;

The steps a and b are in no particular order.

Based on the above solution, preferably, the printing material is prepared by mixing spherical titanium powder and a binder.

Based on the above solution, preferably, the ratio of the spherical titanium powder to the binder is 10:1-5:1; the particle size of the spherical titanium powder is 50-200 microns.

Based on the above solution, preferably, the ratio of the spherical titanium powder to the binder is 10:1; the particle size of the spherical titanium powder is 50 microns.

The conductive partition plate with the gas-liquid distribution flow field structure for the above-mentioned PEM electrolytic cell can also be processed and formed by an etching method; the etching method includes the following steps:

a. Coating protective layer: Coating resin protective layer on the surface of metal plate;

b. The coating is dry;

C. exposure and development: utilize the development template to cover the area to be etched 1, and the non-etched area is exposed to ultraviolet light, so that the resin in this area is cured;

d. Cleaning the uncured coating: the metal plate treated in step c is cleaned with detergent to remove the uncured resin;

e. Initial etching: the metal plate processed in step d is sent to the etching machine for etching;

f. Stripping cleaning: the metal plate treated in step e is cleaned and stripped with a cleaning agent;

g. Etching again: according to the steps a to f, the areas II to X to be etched are respectively etched, and the required etching depths of the areas to be etched I to X are all different, X≥II, after the etching is completed, the conductive Partition plate.

Based on the above solution, preferably, in the to-be-etched regions I to X, the required etching depths are sequentially increased.

Based on the above solution, preferably, the resin is urethane acrylate (urethane acrylate), epoxy acrylate or modified epoxy acrylate; the thickness of the protective layer is 0.5-1 mm; in the step b , the drying temperature is 60-80°C, and the drying time is 30-60min; in the step c, the exposure time is 10-15min; in the step d, the cleaning solvent is one or more of benzene, toluene, and xylene. kind.

Based on the above scheme, preferably, the thickness of the protective layer is 0.7 mm; in the step b, the drying temperature is 80° C., and the drying time is 30 minutes; in the step c, the exposure time is 10 minutes; in the step d, The cleaning solvent was toluene.

Based on the above scheme, preferably, in the step e, the concentration of the etching solution sprayed from the nozzle of the etching machine is 10-50 wt.%; the nozzle pressure is 0.5-1.5 psi; and the etching time is 10-30 min.

Based on the above solution, preferably, the nozzle pressure is 1.0 psi, the etching time is 10 min, and the etching solution concentration is 20 wt.%.

Based on the above scheme, preferably, in the step g, the concentration of the etching solution is 10-100 wt.%, the etching time is 5-15 min, the nozzle pressure is 0.5-3.0 psi, preferably the concentration of the etching solution is 100 wt.%, and the etching time is 10 min, the nozzle pressure was 1.5 psi, and other preparation conditions were the same as those used in the initial etching.

Based on the above scheme, preferably, in the step f, the cleaning agent is an alkaline solution with a concentration of 20-70 wt.%, preferably a potassium hydroxide solution with a concentration of 30 wt.%.

The above-mentioned preparation method provided by the present invention greatly simplifies the processing link of the conductive separator, improves the structural stability of the conductive separator, reduces the bonding interface of the sealing structure, and reduces the leakage risk of substances in the stack.

The conductive separator prepared by the above method of the present invention can be applied to fuel cells, renewable fuel cells, photoelectric catalytic devices, electrolytic hydrogen generator devices or electrochemical hydrogen compressors.

beneficial effect

1. The conductive partition plate prepared by the method provided by the present invention is integrally processed and formed, without independent plate and frame components, and is a whole plate structure; while the plate and frame components of the traditional water electrolysis conductive partition plate are separated from the main body of the conductive partition plate, Oxygen and electrolyte inlet and outlet, hydrogen inlet and outlet, sealant grooves, positioning holes, bridge areas and other structures need to be processed separately.

2. The difference between the conductive separator processed by the method provided by the present invention and the integrated conductive separator of the fuel cell is that the integrated conductive separator of the fuel cell still needs to process two unipolar plates separately and combine them. However, the conductive separating plate obtained by the technical solution is a whole plate structure with only a single plate, and does not need to be formed by two unipolar plates.

3. The difference between the conductive separators processed by the method provided by the present invention and the separators of traditional fuel cells and electrolysis cells is that in the stack of the filter press structure, the separators using this technical solution can be used. The leakage risk area of the equipment is reduced to half of the original number, which greatly reduces the leakage risk of the stack.

4. In the present invention, the sealing glue line groove, the diversion groove and the flow field are all processed on the main material of the separator; this water electrolysis conductive separator integrates each functional area of the conductive separator; the assembly process is simplified. , reducing the processing difficulty of the electrode plate, ensuring the assembly quality and positioning accuracy of the hole channel; and the electrode plate formed by the whole plate does not need to be reinforced separately for the sealant groove, which can ensure the high-voltage operation stability of the electrolytic cell.

5. Compared with the conductive separator obtained by the preparation method provided by the present invention, the assembly quality and positioning accuracy of the stack are guaranteed; the conductive separator optimized by this method It has better performance when used in proton exchange membrane (PEM) water electrolysis cells; the conductive separator provided by the invention is used in fuel cells, renewable fuel cells, photoelectric catalysis, electrolytic hydrogen generator devices, and electrochemical hydrogen compressors There is a wide range of use value.

6. The conductive separator in water electrolysis needs to cooperate with the permeable plate to complete the assembly of the stack. The permeable plate is usually a metal porous material or metal mesh with a certain thickness, which plays the role of conducting electricity and permeating water. A concave surface with a certain depth is made on the separator, that is, the depth difference between the upper surface of the sealing groove and the plane where the central flow field ridge is located, and a water permeable plate is placed. The fuel cell usually does not need to match the metal water permeable plate. Therefore, the present invention adopts the etching method. Control of etching conditions (etching solution concentration and pressure), and etching different areas under different conditions, realize the synthesis of multi-level depth difference conductive separators, and can seal the bottom of the sealant line grooves of the metal conductive separators The roughness of the plane is adjusted, and it is sealed with the metal permeable plate to achieve effective sealing under high pressure environment.

Description of drawings

1. A schematic diagram of a conductive separator (oxygen side) with a gas-liquid distribution flow field structure for a PEM electrolyzer;

Figure 2. A schematic diagram of a conductive separator (hydrogen side) with a gas-liquid distribution flow field structure for a PEM electrolyzer;

Figure 3. Exploded view of the structure of the existing conductive separator;

Figure 4. A schematic diagram of a conductive partition plate with a gas-liquid channel and no distribution flow field structure;

Figure 5. Schematic diagram of the stack leakage risk interface structure;

In the figure, 1. Cathode/Anode material inlet and outlet; 2. Sealant trunking; 3. Flow field area; 4. Positioning hole; 5. Bridge area; 6. Plate frame assembly; 7. Conductive separator body; 8. Risk of material leakage inside the stack.

detailed description

The embodiments of the present invention will be described in detail below with reference to the accompanying drawings and examples, so as to fully understand the implementation process of how the present invention applies technical means to solve technical problems and achieve technical effects.

Example 1

This embodiment provides a conductive separator with a gas-liquid distribution flow field structure for a PEM electrolytic cell. The structure is shown in FIG. 1 . The conductive separator is a whole plate structure. One side is oxygen and electrolyte flow field (ie anode flow field), the other side is hydrogen flow field (ie cathode flow field); both ends of described conductive separator A are provided with anode material inlet and outlet (ie oxygen, electrolyte The inlet and outlet of the gas-liquid mixture) and the inlet and outlet of the cathode material (that is, the inlet and outlet of the hydrogen gas); the inlet and outlet of the anode material are respectively located at both ends of the width direction of the conductive separator, and are symmetrical in the center; the inlet and outlet of the cathode material are The outlets are respectively located at both ends of the conductive separator in the width direction, and are symmetrical in the center; the inlet and outlet of the anode material and the inlet and outlet of the cathode material are rectangular.

There are sealant line grooves 2 around the inlet and outlet and the flow field; a bridge area 5 is arranged between the anode material inlet and outlet and the anode flow field, which is used to connect the anode flow field and the anode material inlet. Export.

The four corners of the conductive partition plate A are provided with positioning holes 4 for fixing the conductive partition plate to the external structure.

The anode flow field is linear, and the anode flow field includes several flow channels parallel to each other; the cathode flow field is a plane area.

The above-mentioned conductive separator is prepared by an etching method, and the etching processing method comprises the following steps:

1. Coating the protective layer: Coating the resin protective layer on the surface of the metal plate, the thickness of the coating is kept at 0.3-0.5mm; and drying is carried out, and the drying condition is 60 ℃, 30min.

2. Exposure and development: use the developing template to cover the area to be etched, and expose the area to be protected with ultraviolet light to cure the resin in this area. Lose.

3. Initial etching: The metal device coated with the cured resin protective layer is sent to the etching machine for etching. The pressure of the etching solution sprayed from the nozzle of the etching machine is 0.8psi, the etching time is 60min, and the concentration of the etching solution is 5wt.%HF solution;

The initial etching is carried out by spraying the etching solution on both sides, and the areas to be processed are as follows:

Cathode/anode material inlet and outlet (anode material inlet and outlet are oxygen and electrolyte gas-liquid mixture inlet and outlet, cathode material inlet and outlet are hydrogen inlet and outlet), positioning hole, sealant groove area, anode material inlet and outlet and anode flow The bridge region between the fields, the anode flow field region and the cathode flow field region.

Among them, the sealant line groove area and the cathode flow field area can be completed after the first etching, and the cathode flow field area after etching is shown in Figure 2; Flow field plane area), it needs to be etched again to further process the groove; the cathode/anode material inlet and outlet and the positioning hole are half-etched after the initial etching, and need to be cut and blanked by mechanically assisted processing.

4. Defilm cleaning: The conductive separator after the initial etching is cleaned and removed, and the cleaning agent can be selected as a potassium hydroxide solution with a concentration of 30 wt.%.

5. Re-etching: Re-etching adopts the method of spraying etching solution on one side to process the grooves in the anode flow field area and the bridge area. The specific steps are as follows: The anode flow field of the separator needs to be processed into the grooves. The plane parts of the flow field area and the bridge area are coated with a protective layer, and the corresponding area of the flow field groove to be processed is exposed, followed by exposure and development, etching processing, and stripping cleaning according to the above 1 to 4 procedures in turn to obtain the final product. , the etching solution concentration in the re-etching process is 100wt.%, the etching time is 10min, the nozzle pressure is 1.5psi, and other preparation conditions are the same as those used in the initial etching. The etched cathode/anode material inlet and outlet and positioning holes are cut and blanked to obtain a conductive separator A (the structure is shown in Figure 1).

Assemble the stack A with the conductive separator A prepared by the above method in Section 10, and conduct the tightness test. The operation method is as follows:

Connect the 15MPa gas cylinder with the pressure-resistant pipeline for the stack. An exhaust valve should be added on one side of the stack, and a stop valve and a pressure gauge should be added at the front end of the pressure reducing valve of the gas cylinder. Helium gas of different pressures should be used for pressure sealing test.

Through the test results, it is found that the stack A has no leakage at 5MPa, and no obvious sealing failure.

Example 2

This embodiment provides a conductive separator with a gas-liquid distribution flow field structure for a PEM electrolytic cell. The structure of the conductive separator is the same as that of Embodiment 1, and the difference from Embodiment 1 is that this embodiment The conductive separators of the 3D printing method are prepared by the 3D printing method; the steps of the 3D printing method are as follows:

1. 3D modeling: According to the shape and size of the conductive partition plate to be printed, design the shape of each functional area, the shape of the section, etc.; Figures are processed in two-dimensional slices.

2. Preparation of printing material: The spherical titanium powder with a particle size of ~70 microns and a binder are prepared into a printing material in a ratio of 15:1.

3. Input the modeling graphics in step 1 into the 3D printing printing program according to the format, and send the printing materials prepared in step 2 into the printing equipment. The printing materials are alternately printed and stacked.

4. The control component starts the conveying action of the printing platform, operates the printing platform to send the conductive partition plate printed in step 3 out of the printing system, completes the printing, and obtains the conductive partition plate B with the gas-liquid distribution flow field.

Use 10 conductive separators B prepared according to the above steps to assemble the stack B, and conduct the tightness test. The operation method is as follows:

Through the test results, it is found that the stack B has no leakage at 5MPa, and no obvious sealing failure.

Comparative Example 1

In order to achieve high-pressure gas sealing above 4MPa, it is necessary to finely adjust the roughness of the bottom plane of the sealant groove of the metal conductive separator. The adjustment process is as follows:

The conductive separator C with flow field is processed according to the steps described in Example 1, wherein the processing of the sealant groove is performed during the initial etching process, and the difference from Example 1 is:

1. When processing the sealant line groove on the conductive partition plate C, the concentration of the etching solution used is relatively low, which is one-fifth of the concentration of the etching solution again, that is, the HF solution with a concentration of 20wt.%;

2. When processing the sealant line groove on the conductive separator C, the pressure of the etching solution sprayed from the nozzle of the etching machine is reduced to half of the etching operation again, about 0.4psi, and the etching time is 30-60min;

Ten cell stacks were assembled with conductive separators C for tightness testing. The assembled stack was stack C, which was compared with stack A in Example 1. The comparison test results showed that stack C occurred at 4.5 MPa. There is no leakage, while the stack A can still maintain good sealing performance at 5.5MPa, and there is no obvious sealing failure.

Comparative Example 2

In order to highlight that the conductive separation plate of the present invention has advantages in stack sealing compared to the conductive separation plate processed by the traditional method, the two are compared, and the operation method is as follows:

1. Use 10 sections of the conductive separators prepared in Example 1 and other necessary components to assemble an electrolytic cell stack A, and use 10 sections of the same size of the traditional process to prepare the combined conductive separators (as shown in Figure 2) and Other necessary components are assembled into electrolytic cell stack D;

2. The stack A and stack D are assembled in the following way: connect the 15MPa gas cylinder to the stack with pressure-resistant pipeline, add an exhaust valve on one side of the stack, and add a stop valve and Pressure gauge, using different pressures of helium for pressure sealing test;

Through the comparative test results, it is found that the stack D leaks at 2.5MPa, and the seal is extruded, while the stack A can still maintain good sealing performance at 4MPa, and there is no obvious seal failure.

Claims

A conductive separator with a gas-liquid distribution flow field structure for PEM electrolyzers, characterized in that the conductive separator is a whole-plate structure; one side of the conductive separator is provided with an anode flow field, and the other side is provided with an anode flow field. A cathode flow field is provided; both ends of the conductive separator are provided with an anode material inlet and outlet and a cathode material inlet and outlet.
The conductive partition plate according to claim 1, wherein each inlet and outlet and the periphery of the flow field are provided with sealant grooves.
The conductive separator according to claim 1, wherein a bridge area is provided between the anode material inlet and outlet and the anode flow field for connecting the anode material inlet and outlet with the anode flow field.
The conductive partition plate according to claim 1, wherein four corners of the conductive partition plate are provided with positioning holes for fixing the conductive partition plate to the external structure.
The conductive separator according to claim 1, wherein the anode material inlet and outlet are respectively located at both ends of the conductive separator in the width direction, and are centrally symmetric; the cathode material inlet and outlet are respectively located at the opposite ends of the conductive separator. Both ends of the conductive separator in the width direction are centrally symmetric.
The conductive separator according to claim 1, wherein the anode material inlet and outlet and the cathode material inlet and outlet are rectangular.
The conductive separator according to claim 4, wherein the length of the inlet and outlet of the anode material is greater than the length of the inlet and outlet of the cathode material.
The conductive separator according to claim 1, wherein the anode flow field is linear, the anode flow field includes a plurality of flow channels parallel to each other, and the cathode flow field is a plane area.
An application of the conductive separator according to any one of claims 1 to 8 in a fuel cell, a renewable fuel cell, a photoelectric catalytic device, an electrolytic hydrogen generator device or an electrochemical hydrogen compressor.