A conductive separator with a gas-liquid distribution flow field structure

Abstract

The present invention relates to a conductive separator plate with a gas-liquid distribution flow field structure and a processing method thereof, wherein functional partitions such as a sealant wire trough, a guide trough, a gas channel, and a liquid channel are integrated into the same component and formed in one piece. Compared with traditional conductive separator plates, the conductive separator plate of the present invention reduces the number of processing times and the difficulty of processing, so that the manufacturing of the conductive separator plate, the assembly quality of the battery stack, and the positioning accuracy are all guaranteed. The conductive separator plate of the present invention does not require separate reinforcement of the sealant wire trough, and can ensure the operating stability of the electrolytic cell under the condition of producing high-pressure hydrogen (>3.5MPa). Compared with the prior art, the conductive separator plate of the present invention has a simple structure, is easy and reliable to install, reduces the processing steps, and improves the structural reliability.

Description

Technical Field

[0001] The invention belongs to the field of electrochemistry, and in particular relates to a conductive partition plate with a gas-liquid distribution flow field structure. Background Art

[0002] The conductive separator is one of the core components of the electrolytic cell for hydrogen production by electrolysis, which directly affects the electrolysis efficiency, electrolysis energy consumption, electrolysis cost and the life of the electrolytic cell.

[0003] The structure of the existing conductive separator for hydrogen production by water electrolysis is relatively complex, including multiple structural modules such as the main body, plate-frame components, and sealing structures. These structural modules are often processed separately as independent components. The processing flow of this type of conductive separator is complicated and requires high positioning accuracy, which brings many inconveniences to the mass production and assembly of the conductive separator. In addition, as an independently processed plate-frame component, it is necessary to keep it connected to the main body of the conductive separator by bonding or welding. This type of connection method will cause problems such as loose connection and excessive deformation of the flatness of the conductive separator, which is not conducive to the operation of the electrolytic cell under heating and high-pressure operating conditions.

[0004] Specifically, the existing conductive separators for water electrolysis have the following main problems: 1. The plate-frame assembly of the conductive separator needs to be processed separately, which causes the plate-frame assembly and the conductive separator body to need to repeat the same processing, resulting in increased processing costs; 2. The positioning accuracy requirements of the positioning holes of the conductive separator and the positioning holes of the conductive separator body are high, resulting in higher assembly difficulty; 3. The existing conductive separator sealant wire grooves need to be reinforced by bonding or welding, which complicates the processing flow of the conductive separator and cannot guarantee the reliability of the sealing function of the conductive separator under high-voltage operation of the electrolytic cell; 4. In the fuel cell stack with a filter press structure, there are many sealing interfaces of the equipment, and the risk of leakage of materials inside the fuel cell 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 and ridge structures on both sides of the whole plate, which is not suitable for water electrolysis. Summary of the invention

[0005] In view of the above problems, the present invention provides a conductive separator with a gas-liquid distribution flow field structure. The conductive separator is a whole plate structure and can be used in a water electrolysis hydrogen production device.

[0006] The technical solution of the present invention is as follows:

[0007] The present invention provides a conductive separator plate with a gas-liquid distribution flow field structure, wherein the conductive separator plate is a whole plate structure; one side of the conductive separator plate is provided with an anode flow field, and the other side is provided with a cathode flow field; both ends of the conductive separator plate are provided with an anode material inlet and an cathode material inlet.

[0008] Based on the above solution, preferably, sealant wire grooves are provided around the inlet and outlet and the flow field.

[0009] 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.

[0010] Based on the above solution, preferably, positioning holes are provided at four corners of the conductive separator plate for fixing the conductive separator plate to an external structure.

[0011] Based on the above scheme, preferably, the anode material inlet and outlet are respectively located at both ends of the width direction of the conductive separator and are centrally symmetrical; the cathode material inlet and outlet are respectively located at both ends of the width direction of the conductive separator and are centrally symmetrical.

[0012] Based on the above solution, preferably, the anode material inlet and outlet and the cathode material inlet and outlet are rectangular.

[0013] Based on the above solution, preferably, the anode flow field is linear, and the anode flow field includes a plurality of flow channels parallel to each other; and the cathode flow field is a plane area.

[0014] In the above-mentioned conductive partition plate, the plate-frame assembly is no longer separated from the conductive partition plate body, but is integrally formed as a part of the conductive partition plate.

[0015] The cathode / anode material inlet and outlet, positioning holes, and bridge area in the plate-frame assembly are integrally formed with the conductive separator plate body, and there is no need to repeatedly process the same structure as the conductive separator plate body.

[0016] The sealant wire duct is integrally formed with the conductive partition plate body, and no additional connection method is required to fix the sealant wire duct to the conductive partition plate body.

[0017] The conductive partition plate with the gas-liquid distribution flow field structure can be formed by 3D printing; the 3D printing method includes the following steps:

[0018] a. Three-dimensional modeling: making a three-dimensional model of the conductive separator to be printed in a computer, and performing two-dimensional slicing on the three-dimensional model;

[0019] b. Prepare printing materials;

[0020] c. Input the modeling graphics in step a into the 3D printing program according to the format; send the printing material prepared in step b into the printing device, and the printing nozzle and the printing platform in the printing device cooperate with each other to print and stack the printing materials alternately, and after printing is completed, a conductive separator with a whole plate structure is obtained;

[0021] d. Sending the conductive separator plate printed in step c out of the printing system;

[0022] The steps a and b are performed in no particular order.

[0023] Based on the above solution, preferably, the printing material is prepared by mixing spherical titanium powder and a binder.

[0024] Based on the above solution, preferably, the ratio of the spherical titanium powder to the binder is 10:1 to 5:1; and the particle size of the spherical titanium powder is 50 to 200 microns.

[0025] Based on the above solution, preferably, the ratio of the spherical titanium powder to the binder is 10:1; and the particle size of the spherical titanium powder is 50 microns.

[0026] The conductive partition plate with the gas-liquid distribution flow field structure can also be formed by etching; the etching method includes the following steps:

[0027] a. Coating protective layer: Coating a resin protective layer on the surface of the metal plate;

[0028] b. Coating drying;

[0029] c. Exposure and development: Cover the area to be etched I with a developing template, and expose the non-etched area to ultraviolet light to cure the resin in the area;

[0030] d. Cleaning the uncured coating: Clean the metal plate treated in step c with a detergent to remove the uncured resin;

[0031] e. Initial etching: The metal plate treated in step d is fed into an etching machine for etching;

[0032] f. Demolding and cleaning: The metal plate treated in step e is cleaned and demolded using a cleaning agent;

[0033] g. Etching again: Etching the regions II to X to be etched respectively according to steps a to f, wherein the etching depths required for the regions I to be etched are different, X≥II, and after etching, the conductive separator is obtained.

[0034] Based on the above solution, preferably, in the regions I to X to be etched, the required etching depths increase successively.

[0035] Based on the above scheme, preferably, the resin is urethane acrylate (polyurethane acrylate), epoxy acrylate or modified epoxy acrylate; the thickness of the protective layer is 0.5 to 1 mm; in the step b, the drying temperature is 60 to 80°C, and the drying time is 30 to 60 min; in the step c, the exposure time is 10 to 15 min; in the step d, the cleaning solvent is one or more of benzene, toluene, and xylene.

[0036] 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 min; in the step c, the exposure time is 10 min; in the step d, the cleaning solvent is toluene.

[0037] 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 10-50wt.%; the nozzle pressure is 0.5-1.5psi; and the etching time is 10-30min.

[0038] Based on the above scheme, preferably, the nozzle pressure is 1.0 psi, the etching time is 10 min, and the etching solution concentration is 20 wt.%.

[0039] Based on the above scheme, preferably, in the step g, the etching solution concentration is 10-100wt.%, the etching time is 5-15min, and the nozzle pressure is 0.5-3.0psi, preferably the etching solution concentration is 100wt.%, the etching time is 10min, the nozzle pressure is 1.5psi, and the other preparation conditions are the same as those used in the initial etching.

[0040] Based on the above scheme, preferably, in step f, the cleaning agent is an alkali solution with a concentration of 20 to 70 wt.%, preferably a potassium hydroxide solution with a concentration of 30 wt.%.

[0041] The above-mentioned preparation method provided by the present invention greatly simplifies the processing steps of the conductive separator, improves the structural stability of the conductive separator, reduces the bonding interface of the sealing structure, and reduces the risk of leakage of substances in the fuel cell stack.

[0042] The conductive separator prepared by the above method of the present invention can be applied to fuel cells, renewable fuel cells, photoelectrocatalytic devices, electrolytic hydrogen generator devices or electrochemical hydrogen compressors.

[0043] Beneficial Effects

[0044] 1. The conductive separator plate prepared by the method provided by the present invention is integrally processed and formed without independent plate-frame components, and is a whole plate structure; whereas the plate-frame components of the conventional water electrolysis conductive separator plate are separated from the conductive separator plate body, and the oxygen and electrolyte inlets and outlets, hydrogen inlets and outlets, sealant wire grooves, positioning holes, bridge areas and other structures need to be processed separately.

[0045] 2. The difference between the conductive separator plate processed by the method provided by the present invention and the integrated conductive separator plate of the fuel cell is that the integrated conductive separator plate of the fuel cell still needs to be processed and combined with two monopolar plates separately, while the conductive separator plate obtained by the present technical solution is a whole plate structure of only a single plate, and does not require two monopolar plates.

[0046] 3. The difference between the conductive separator processed by the method provided by the present invention and the separator of the traditional fuel cell and electrolytic cell is that: in the fuel cell stack with a filter press structure, the separator using the technical solution can reduce the risk of sealing leakage of the equipment to half of the original number, greatly reducing the risk of leakage of the fuel cell stack.

[0047] 4. The present invention completes the processing of the sealant wire groove, guide groove and flow field on the main material of the separator plate; this water electrolysis conductive separator plate integrates the various functional areas of the conductive separator plate; simplifies the assembly process, reduces the processing difficulty of the electrode plate, and ensures the assembly quality and positioning accuracy of the channel; and the electrode plate formed as a whole plate does not require separate reinforcement of the sealant wire groove, which can ensure the high-voltage operation stability of the electrolytic cell.

[0048] 5. Compared with the conductive separators processed by traditional processes, the conductive separators obtained by the preparation method provided by the present invention have guaranteed assembly quality and positioning accuracy of the fuel cell stack; the conductive separators optimized by the present method have better performance when used in proton exchange membrane (PEM) water electrolysis cells; the conductive separators provided by the present invention have wide application value in fuel cells, renewable fuel cells, photoelectrocatalysis, electrolytic hydrogen generator devices, and electrochemical hydrogen compressors.

[0049] 6. The conductive separator in water electrolysis needs to cooperate with the water-permeable plate to complete the assembly of the battery stack. The water-permeable plate is usually a metal porous material or metal mesh with a certain thickness, which plays a role of conductivity and water permeability. Therefore, it is necessary to make a concave surface of a certain depth on the conductive 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, to place the water-permeable plate. Fuel cells usually do not need to cooperate with metal water-permeable plates. Therefore, the present invention controls the etching conditions (etching solution concentration and pressure) in the etching method, and etches different areas under different conditions to achieve the synthesis of multi-level depth difference conductive separators, and can adjust the roughness of the bottom plane of the sealant wire groove of the metal conductive separator, and cooperate with the metal water-permeable plate to seal, so as to achieve effective sealing under high pressure environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 . Schematic diagram of a conductive separator plate (oxygen side) with a gas-liquid distribution flow field structure;

[0051] Figure 2 . Schematic diagram of a conductive separator plate (hydrogen side) with a gas-liquid distribution flow field structure;

[0052] Figure 3 . Exploded view of the existing conductive separator structure;

[0053] Figure 4. Schematic diagram of a conductive partition plate with a gas-liquid channel and a non-distribution flow field structure;

[0054] Figure 5 .Schematic diagram of the stack leakage risk interface structure;

[0055] In the figure, 1. cathode / anode material inlet and outlet; 2. sealant wire trough; 3. flow field area; 4. positioning hole; 5. bridge area; 6. plate and frame assembly; 7. conductive separator body; 8. risk surface of material leakage inside the fuel cell stack. DETAILED DESCRIPTION

[0056] The following will describe the implementation modes of the present invention in detail with reference to the accompanying drawings and embodiments, so as to fully understand how the present invention applies technical means to solve technical problems and achieve the implementation process of technical effects.

[0057] Example 1

[0058] This embodiment provides a conductive partition plate with a gas-liquid distribution flow field structure, the structure is as follows Figure 1 As shown, the conductive separator plate is a whole plate structure, one side of the conductive separator plate A is an oxygen and electrolyte flow field (i.e., an anode flow field), and the other side is a hydrogen flow field (i.e., a cathode flow field); both ends of the conductive separator plate A are provided with an anode material inlet and outlet (i.e., an inlet and outlet of a gas-liquid mixture of oxygen and electrolyte) and a cathode material inlet and outlet (i.e., a hydrogen inlet and outlet); the anode material inlet and outlet are respectively located at the two ends of the width direction of the conductive separator plate, and are centrally symmetrical; the cathode material inlet and outlet are respectively located at the two ends of the width direction of the conductive separator plate, and are centrally symmetrical; the anode material inlet and outlet and the cathode material inlet and outlet are rectangular.

[0059] A sealing rubber groove 2 is provided around each inlet and outlet and the flow field; a bridge area 5 is provided between the anode material inlet and outlet and the anode flow field to connect the anode flow field and the anode material inlet and outlet.

[0060] Positioning holes 4 are provided at the four corners of the conductive partition plate A for fixing the conductive partition plate to the external structure.

[0061] The anode flow field is linear and includes a plurality of flow channels parallel to each other; the cathode flow field is a plane area.

[0062] The conductive separator is prepared by etching, and the etching process comprises the following steps:

[0063] 1. Coating protective layer: Coat the surface of the metal plate with a resin protective layer, with the coating thickness maintained at 0.3-0.5 mm; and perform drying treatment at 60°C for 30 minutes.

[0064] 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. The exposure time is 5 to 10 minutes, and then use toluene detergent to clean the board to remove the uncured resin.

[0065] 3. Initial etching: The metal device coated with the cured resin protective layer is sent to the etching machine for etching. The etching liquid pressure sprayed from the nozzle of the etching machine is 0.8 psi, the etching time is 60 minutes, and the etching liquid concentration is 5wt.% HF solution;

[0066] The initial etching is carried out by double-sided spraying of etching liquid. The areas that need to be processed are as follows:

[0067] Cathode / anode material inlet and outlet (the anode material inlet and outlet are the inlet and outlet of the gas-liquid mixture of oxygen and electrolyte, and the cathode material inlet and outlet are the inlet and outlet of hydrogen), positioning holes, sealant wire groove area, bridge area between the anode material inlet and outlet and the anode flow field, anode flow field area and cathode flow field area.

[0068] Among them, the sealant line slot area and the cathode flow field area can be completed after the initial etching. The cathode flow field area after etching is as follows Figure 2 As shown; the anode flow field area and the bridge area are flat areas (same as the cathode flow field flat area) after the initial etching, and need to be further etched to form grooves; the cathode / anode material inlet and outlet and the positioning holes are in a semi-etched state after the initial etching, and need to be cut with the help of mechanical assistance.

[0069] 4. Demolding and cleaning: Clean and demold the conductive partition after the initial etching. The cleaning agent can be a potassium hydroxide solution with a concentration of 30wt.%.

[0070] 5. Etching again: The etching again adopts the method of single-sided spraying etching liquid to process the grooves in the anode flow field area and the bridge area. The specific steps are as follows: the flow field area and the plane part of the bridge area of ​​the anode flow field of the separator plate where the grooves need to be processed are coated with a protective layer, and the corresponding area of ​​the flow field grooves to be processed is exposed, and the exposure and development, etching processing, and film stripping and cleaning are carried out in accordance with the above 1 to 4 processes to obtain the final product. The etching liquid concentration in the re-etching process is 100wt.%, the etching time is 10min, the nozzle pressure is 1.5psi, and the other preparation conditions are the same as those used in the initial etching. After etching, the half-etched cathode / anode material inlet and outlet and the positioning hole are cut and blanked by mechanical auxiliary processing to obtain a conductive separator A (structure as Figure 1 shown).

[0071] Use the conductive separator A prepared by the method in Section 10 to assemble the stack A and perform a sealing test. The operation method is as follows:

[0072] Connect the 15MPa gas cylinder to the fuel cell stack with a pressure-resistant pipeline. An exhaust valve is required on one side of the fuel cell stack. A stop valve and a pressure gauge are required at the front end of the gas cylinder pressure reducing valve. Use helium at different pressures to perform pressure sealing tests.

[0073] The test results showed that stack A had no leakage at 5MPa and no obvious sealing failure.

[0074] Example 2

[0075] This embodiment provides a conductive separator with a gas-liquid distribution flow field structure. The structure of the conductive separator is the same as that of Embodiment 1. The difference from Embodiment 1 is that the conductive separator of this embodiment is prepared by 3D printing. The steps of the 3D printing method are as follows:

[0076] 1. Three-dimensional modeling: According to the shape and size of the conductive separator to be printed, design the shape of each functional area, the shape of the cross section, etc.; make a three-dimensional model of the designed conductive separator in the computer, and perform two-dimensional slicing on the three-dimensional model.

[0077] 2. Preparation of printing materials: Spherical titanium powder with a particle size of 70 μm and a binder are prepared into printing materials in a ratio of 15:1.

[0078] 3. Input the modeling graphics in step 1 into the 3D printing program according to the format, and send the printing material prepared in step 2 into the printing device. The print head and the printing platform in the printing device cooperate with each other to alternately print and stack the printing materials prepared in step 2.

[0079] 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.

[0080] Use 10 sections of conductive separators B made according to the above steps to assemble the battery stack B and perform a sealing test. The operation method is as follows:

[0081] Connect the 15MPa gas cylinder to the fuel cell stack with a pressure-resistant pipeline. An exhaust valve is required on one side of the fuel cell stack. A stop valve and a pressure gauge are required at the front end of the gas cylinder pressure reducing valve. Use helium at different pressures to perform pressure sealing tests.

[0082] The test results showed that stack B had no leakage at 5MPa and no obvious sealing failure.

[0083] Comparative Example 1

[0084] 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 wire groove of the metal conductive partition plate. The adjustment process is as follows:

[0085] The conductive partition plate C with a flow field is processed according to the steps described in Example 1, wherein the processing of the sealant wire groove is performed during the initial etching process. The difference from Example 1 is that:

[0086] 1. When processing the sealant wire 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 second etching solution, that is, a 20wt.% HF solution;

[0087] 2. When processing the sealant groove on the conductive partition plate C, the pressure of the etching liquid sprayed from the nozzle of the etching machine is reduced to half of that during the second etching operation, which is about 0.4 psi, and the etching time is 30 to 60 minutes;

[0088] Ten fuel cells were assembled using conductive partition plates C for sealing tests. The assembled fuel cell was called fuel cell C and compared with fuel cell A in Example 1. The comparative test results showed that fuel cell C leaked at 4.5 MPa, while fuel cell A could still maintain good sealing at 5.5 MPa without obvious sealing failure.

[0089] Comparative Example 2

[0090] In order to highlight the advantages of the conductive separator of the present invention over the conductive separator processed by the traditional method in terms of stack sealing, the two are compared, and the operation method is as follows:

[0091] 1. Ten conductive separators prepared in Example 1 and other necessary components are assembled into an electrolytic cell stack A. Ten combined conductive separators (such as Figure 2 As shown) and other necessary components are assembled into an electrolytic cell stack D;

[0092] 2. Both stack A and stack D are assembled in the following manner: connect the 15MPa gas cylinder to the stack with a pressure-resistant pipeline, add an exhaust valve on one side of the stack, add a stop valve and a pressure gauge on the front end of the gas cylinder pressure reducing valve, and use helium at different pressures for pressure sealing test;

[0093] By comparing the test results, it was found that stack D leaked at 2.5MPa and there was seal extrusion, while stack A could still maintain good sealing at 4MPa without obvious sealing failure.

Claims

1. A conductive separator with a gas-liquid distribution flow field structure, 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 a cathode flow field; both ends of the conductive separator are provided with an anode material inlet and an cathode material inlet; Sealant wire grooves are provided around each inlet and outlet and the flow field; 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; The four corners of the conductive partition plate are provided with positioning holes for fixing the conductive partition plate to the external structure; The anode material inlet and outlet are respectively located at the two ends of the width direction of the conductive separator, and are symmetrical to the center; the cathode material inlet and outlet are respectively located at the two ends of the width direction of the conductive separator, and are symmetrical to the center; The conductive partition plate with the gas-liquid distribution flow field structure is formed by etching; the etching method comprises the following steps: a. Coating a protective layer: coating a resin protective layer on the surface of the metal plate; b. Coating drying; c. Exposure and development: Covering the area to be etched using a developing template I, the non-etched area is exposed to ultraviolet light so that the resin in the area is cured; d. Cleaning the uncured coating: The metal plate treated in step c is cleaned with a detergent to clean off the uncured resin; e. Initial etching: The metal plate processed in step d is fed into the etching machine for etching; f. Demolding and cleaning: The metal plate treated in step e is cleaned and demolded using a cleaning agent; g. Etching again: etching the etching regions II to X respectively according to steps a to f, the etching depths of the etching regions I to X are different, X ≥ II, after etching, the conductive separator is obtained; The resin is 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 to 15 minutes; In the step d, the cleaning solvent is one or more of benzene, toluene and xylene; In the step e, the concentration of the etching solution sprayed from the nozzle of the etching machine is 10-50wt.%; the nozzle pressure is 0.5-1.5psi; and the etching time is 10-30min; In the step g, the etching solution concentration is 10-100 wt.%, the etching time is 5-15 min, and the nozzle pressure is 0.5-3.0 psi; Among them, the areas that need to be processed in the first etching are as follows: cathode / anode material inlet and outlet, positioning holes, sealant wire groove area, bridge area between anode material inlet and outlet and anode flow field, anode flow field area and cathode flow field area; the sealant wire groove area and cathode flow field area can be completed after the first etching, and the cathode flow field area becomes a plane area after etching. The anode flow field area and the bridge area are plane areas after the first etching, and need to be further etched to form grooves.

2. The conductive separator according to claim 1, characterized in that: The anode material inlet and outlet and the cathode material inlet and outlet are rectangular.

3. The conductive separator according to claim 1, characterized in that: The length of the anode material inlet and outlet is greater than the length of the cathode material inlet and outlet.

4. The conductive separator according to claim 1, characterized in that: The anode flow field is linear and includes a plurality of flow channels parallel to each other; the cathode flow field is a plane area.

5. Use of the conductive separator according to any one of claims 1 to 4 in a fuel cell, a renewable fuel cell, a photoelectrocatalytic device, an electrolytic hydrogen generator device or an electrochemical hydrogen compressor.

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