An integrated fuel cell bipolar plate and a method of making the same

Abstract

This invention discloses an integrated fuel cell bipolar plate and its preparation method. The method includes the following steps: S01, uniformly spreading a first mixed powder in a mold to obtain a first mixed powder layer; uniformly spreading a pore-forming material on the first mixed powder layer to obtain a pore-forming material layer; uniformly spreading a second mixed powder on the pore-forming material layer to obtain an integrated bipolar plate powder; S02, pressing the integrated bipolar plate powder at 140℃~160℃ to obtain an integrated bipolar plate; heating the integrated bipolar plate to 200℃~230℃ and maintaining it for 2h~3h to obtain an integrated bipolar plate with flow channels; S03, immersing the integrated bipolar plate with flow channels in an acrylic resin solution, vacuum pressurizing the impregnation, rinsing, and then curing to obtain an integrated fuel cell bipolar plate. The preparation method of this application is simple, has low production cost, and high production efficiency, and can be used for large-scale production of bipolar plates.

Description

Technical Field

[0001] This invention belongs to the field of fuel cell technology, and particularly relates to an integrated fuel cell bipolar plate and its preparation method. Background Technology

[0002] The bipolar plate (BP) of a fuel cell, also known as a flow field plate, is the "skeleton" of the fuel cell stack. It is stacked with the membrane electrode assembly to form the fuel cell stack. In the fuel cell, it plays a role in supporting, collecting current, providing channels for coolant, and separating oxidant and reductant.

[0003] Currently, common bipolar plates (such as graphite engraved plates, metal bipolar plates, and flexible graphite bipolar plates) are basically made by gluing or welding two single plates together to form a bipolar plate, which is then stacked with the membrane electrode assembly (MEA). Some methods integrate the MEA and plates into a single cell, stacking them as single-cell units. Others do not integrate the plates with each other or with the MEA, directly stacking the cathode / anode / MEA. Integrating bipolar plates by gluing them together is a complex process, prone to damage or sealing defects, increasing manufacturing costs. If integration is not performed using common methods, three adhesive strips are needed in a set of plates / MEA, increasing the sealing defect rate and hindering the disassembly and repair of the fuel cell stack, making it difficult to meet the needs of actual production. Summary of the Invention

[0004] This invention provides an integrated fuel cell bipolar plate and its preparation method, aiming to solve the technical problems of existing bipolar plates, such as complex preparation process, high preparation cost, low sealing qualification rate, and difficulty in disassembling and repairing fuel cell stacks.

[0005] To address the aforementioned technical problems, one aspect of this invention provides a method for preparing an integrated fuel cell bipolar plate, comprising the following steps:

[0006] S01. The first mixed powder is evenly spread in the mold to obtain the first mixed powder layer; the forming and pore-forming material is evenly spread on the first mixed powder layer to obtain the forming and pore-forming material layer; the second mixed powder is evenly spread on the forming and pore-forming material layer to obtain the integrated electrode powder.

[0007] S02. The integrated electrode powder is pressurized and molded at 140℃~160℃ to obtain an integrated electrode; the integrated electrode is heated to 200℃~230℃ and held for 2h~3h to obtain an integrated bipolar plate with a cathode flow channel, an anode flow channel and a water flow channel.

[0008] S03. The integrated bipolar plate with cathode flow channel, anode flow channel and water flow channel is immersed in acrylic resin, impregnated under vacuum pressure, rinsed and then cured to obtain an integrated fuel cell bipolar plate.

[0009] In a preferred embodiment, in step S01,

[0010] Both the first mixed powder and the second mixed powder are graphite / adhesive mixed powders; the mass ratio of the first mixed powder to the second mixed powder is 1:1.

[0011] The graphite / adhesive mixed powder is prepared by the following method: 75% to 85% graphite and 15% to 25% adhesive are mixed evenly by dry powder spraying to obtain the graphite / adhesive mixed powder; the percentages are by mass percentage.

[0012] The graphite is expanded graphite; the adhesive is conductive polyaniline.

[0013] The upper mold of the mold is the cathode flow field of the electrode plate, and the lower mold of the mold is the anode flow field of the electrode plate.

[0014] The molding pore-forming material is molded polyvinyl alcohol.

[0015] The molded polyvinyl alcohol is prepared by the following method:

[0016] S11. Polyvinyl alcohol (PVA) and water are mixed at a mass ratio of 1:10 to 1:20 and heated to 80°C to 90°C to obtain a homogeneous solution; a crosslinking agent is added to the homogeneous solution and the mixture is stirred until homogeneous to obtain a mixed solution; the mass of the crosslinking agent is 1% to 3% of the mass of the polyvinyl alcohol.

[0017] S12. Cool the mixed solution to room temperature to obtain a cooled mixed solution; introduce the cooled mixed solution into the electrode water surface flow field mold to obtain polyvinyl alcohol with a flow field shape;

[0018] S13. The polyvinyl alcohol with the flow field shape is dried at 40℃~60℃ to obtain molded polyvinyl alcohol.

[0019] In a preferred embodiment, in step S11,

[0020] The crosslinking agent is borax.

[0021] The stirring time should be continued for 20 to 30 minutes. This ensures that the borax is evenly dispersed.

[0022] In a preferred embodiment, in step S02,

[0023] The pressurization pressure is 25–35 MPa; the pressurization time is 15–20 minutes. The heating is carried out in an inert gas; the inert gas is preferably argon. Through heating, the PVA undergoes high-temperature decomposition, forming a water channel structure inside the electrode plate, resulting in an integrated bipolar plate with cathode, anode, and water channels.

[0024] In a preferred embodiment, in step S03...

[0025] The vacuum pressure impregnation time is preferably 4 to 6 hours; the vacuum pressure impregnation pressure is preferably 0.4 to 0.6 MPa. Impregnation can seal the pores of the electrode plate, ensuring its airtightness.

[0026] The rinsing process involves rinsing with clean water for 30 to 60 minutes.

[0027] The curing process involves curing in hot water at 90–95°C for 30–60 minutes.

[0028] On the other hand, this application embodiment also provides an integrated fuel cell bipolar plate, which is prepared by the above-described preparation method.

[0029] Compared with existing technologies, the technical solution of this invention has the following beneficial effects: This application uses polyvinyl alcohol as the pore-forming material, expanded graphite as the graphite material, borax as the crosslinking agent, and conductive polyaniline as the adhesive to directly prepare an integrated fuel cell bipolar plate. The method of this application eliminates the need for bonding and lamination, reducing production steps, improving production efficiency, and lowering production costs. The preparation method of this application is simple and easy to implement, significantly shortening the bipolar plate preparation cycle, and achieving high production efficiency, making it suitable for large-scale production of bipolar plates. The resulting integrated fuel cell bipolar plate has low contact resistance, high molding efficiency, and excellent performance, meeting the needs of fuel cell applications. Detailed Implementation

[0030] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0031] Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0032] Currently, existing bipolar plates suffer from long fabrication times and low production efficiency. To address these technical problems, this application provides a method for fabricating an integrated fuel cell bipolar plate, comprising the following steps:

[0033] S01. The first mixed powder is evenly spread in the mold to obtain the first mixed powder layer; the forming and pore-forming material is evenly spread on the first mixed powder layer to obtain the forming and pore-forming material layer; the second mixed powder is evenly spread on the forming and pore-forming material layer to obtain the integrated electrode powder.

[0034] S02. The integrated electrode powder is pressurized and molded at 140℃~160℃ to obtain an integrated electrode; the integrated electrode is heated to 200℃~230℃ and held for 2h~3h to obtain an integrated bipolar plate with a cathode flow channel, an anode flow channel and a water flow channel.

[0035] S03. The integrated bipolar plate with cathode flow channel, anode flow channel and water flow channel is immersed in acrylic resin, impregnated under vacuum pressure, rinsed and then cured to obtain an integrated fuel cell bipolar plate.

[0036] This application uses polyvinyl alcohol as the pore-forming material, expanded graphite as the graphite material, borax as the crosslinking agent, and conductive polyaniline as the adhesive to directly prepare an integrated fuel cell bipolar plate. This method eliminates the need for bonding and lamination during integration, reducing production steps, improving production efficiency, and lowering production costs.

[0037] The amount of pore-forming material used varies depending on the electrode design. The pore-forming agent will eventually dissolve, and its mass depends on the size and structural design of the water flow channel, without affecting the overall forming effect of the electrode.

[0038] In a preferred embodiment, in step S01,

[0039] Both the first mixed powder and the second mixed powder are graphite / adhesive mixed powders; the mass ratio of the first mixed powder to the second mixed powder is 1:1.

[0040] The graphite / adhesive mixed powder is prepared by the following method: 75% to 85% graphite and 15% to 25% adhesive are mixed evenly by dry powder spraying to obtain the graphite / adhesive mixed powder; the percentages are by mass percentage.

[0041] The graphite is expanded graphite; the adhesive is conductive polyaniline.

[0042] The upper mold of the mold is the cathode flow field of the electrode plate, and the lower mold of the mold is the anode flow field of the electrode plate.

[0043] The molding pore-forming material is molded polyvinyl alcohol.

[0044] The molded polyvinyl alcohol is prepared by the following method:

[0045] S11. Polyvinyl alcohol (PVA) and water are mixed at a mass ratio of 1:10 to 1:20 and heated to 80°C to 90°C to obtain a homogeneous solution; a crosslinking agent is added to the homogeneous solution and the mixture is stirred until homogeneous to obtain a mixed solution; the mass of the crosslinking agent is 1% to 3% of the mass of the polyvinyl alcohol.

[0046] S12. Cool the mixed solution to room temperature (to slow down the crosslinking reaction rate and provide sufficient time for molding) to obtain a cooled mixed solution; introduce the cooled mixed solution into the electrode water surface flow field mold to obtain polyvinyl alcohol with a flow field shape;

[0047] S13. The polyvinyl alcohol with the flow field shape is dried at 40℃~60℃ (by drying to reduce moisture and increase the stability of the polyvinyl alcohol structure) to obtain molded polyvinyl alcohol.

[0048] In a preferred embodiment, in step S11,

[0049] The crosslinking agent is borax.

[0050] The stirring time should be continued for 20 to 30 minutes. This ensures that the borax is evenly dispersed.

[0051] In a preferred embodiment, in step S02,

[0052] The pressurization pressure is 25–35 MPa; the pressurization time is 15–20 minutes. The heating is carried out in an inert gas; the inert gas is preferably argon. Through heating, the PVA undergoes high-temperature decomposition, forming a water channel structure inside the electrode plate, resulting in an integrated bipolar plate with cathode, anode, and water channels.

[0053] In a preferred embodiment, in step S03...

[0054] The vacuum pressure impregnation time is preferably 4 to 6 hours; the vacuum pressure impregnation pressure is preferably 0.4 to 0.6 MPa. Impregnation can seal the pores of the electrode plate, ensuring its airtightness.

[0055] The rinsing process involves rinsing with clean water for 30 to 60 minutes.

[0056] The curing process involves curing in hot water at 90–95°C for 30–60 minutes.

[0057] In the embodiments of this application, the solution of this application can be achieved as long as the operating conditions are controlled within the above-mentioned range.

[0058] Example 1

[0059] A method for fabricating an integrated fuel cell bipolar plate includes the following steps:

[0060] S01. 30g of the first mixed powder is evenly spread in the mold to obtain the first mixed powder layer; 9g of the forming and pore-forming material is evenly spread on the first mixed powder layer to obtain the forming and pore-forming material layer; 30g of the second mixed powder is evenly spread on the forming and pore-forming material layer to obtain the integrated electrode powder.

[0061] S02. At 160°C, the integrated electrode powder is pressurized and molded to obtain an integrated electrode; the integrated electrode is heated to 220°C and held for 3 hours to obtain an integrated bipolar plate with a cathode flow channel, an anode flow channel and a water flow channel.

[0062] S03. The integrated bipolar plate with cathode flow channel, anode flow channel and water flow channel is immersed in acrylic resin, impregnated under vacuum pressure, rinsed and then cured to obtain an integrated fuel cell bipolar plate.

[0063] In step S01,

[0064] Both the first mixed powder and the second mixed powder are graphite / adhesive mixed powders; the mass ratio of the first mixed powder to the second mixed powder is 1:1.

[0065] The graphite / adhesive mixed powder is prepared by the following method: 80% graphite and 20% adhesive are mixed evenly by dry powder spraying to obtain the graphite / adhesive mixed powder; the percentage is a mass percentage.

[0066] The graphite is expanded graphite; the adhesive is conductive polyaniline.

[0067] The upper mold of the mold is the cathode flow field of the electrode plate, and the lower mold of the mold is the anode flow field of the electrode plate.

[0068] The molding pore-forming material is molded polyvinyl alcohol.

[0069] The molded polyvinyl alcohol is prepared by the following method:

[0070] S11. Polyvinyl alcohol and water are mixed at a mass ratio of 1:10 and heated to 80°C to obtain a homogeneous solution; a crosslinking agent is added to the homogeneous solution, and stirring is continued until homogeneous to obtain a mixed solution; the mass of the crosslinking agent is 3% of the mass of the polyvinyl alcohol;

[0071] S12. Cool the mixed solution to room temperature to obtain a cooled mixed solution; introduce the cooled mixed solution into the electrode water surface flow field mold to obtain polyvinyl alcohol with a flow field shape;

[0072] S13. The polyvinyl alcohol with the flow field shape is dried at 50°C to obtain molded polyvinyl alcohol.

[0073] In step S11, the crosslinking agent is borax; the stirring time is 30 minutes.

[0074] In step S02,

[0075] The pressurization pressure is 30 MPa; the pressurization time is 15 minutes. The heating is carried out in an inert gas; the inert gas is argon.

[0076] In step S03,

[0077] The vacuum pressure impregnation time is 4 hours; the vacuum pressure impregnation pressure is 0.4 MPa.

[0078] The rinsing process involves rinsing with clean water for 30 minutes.

[0079] The curing process involves curing in hot water at 90°C for 30 minutes.

[0080] The fabricated integrated fuel cell bipolar plate was cut and then subjected to airtightness and related performance tests. The results showed that the airtightness of the integrated fuel cell was 0.12 sccm and the contact resistance was 4.3 mΩ·cm. 2 The conductivity is 354 S / cm, meaning that the integrated fuel cell bipolar plate obtained in this application meets the requirements for use of fuel cells and can satisfy the needs of fuel cell use.

[0081] Example 2

[0082] A method for fabricating an integrated fuel cell bipolar plate includes the following steps:

[0083] S01. The first mixed powder is evenly spread in the mold to obtain the first mixed powder layer; the forming and pore-forming material is evenly spread on the first mixed powder layer to obtain the forming and pore-forming material layer; the second mixed powder is evenly spread on the forming and pore-forming material layer to obtain the integrated electrode powder.

[0084] S02. At 140°C, the integrated electrode powder is pressurized and molded to obtain an integrated electrode; the integrated electrode is heated to 200°C and held for 2 hours to obtain an integrated bipolar plate with a cathode flow channel, an anode flow channel and a water flow channel.

[0085] S03. The integrated bipolar plate with cathode flow channel, anode flow channel and water flow channel is immersed in acrylic resin, impregnated under vacuum pressure, rinsed and then cured to obtain an integrated fuel cell bipolar plate.

[0086] In step S01,

[0087] Both the first mixed powder and the second mixed powder are graphite / adhesive mixed powders; the mass ratio of the first mixed powder to the second mixed powder is 1:1.

[0088] The graphite / adhesive mixed powder is prepared by the following method: 75% graphite and 25% adhesive are mixed evenly by dry powder spraying to obtain the graphite / adhesive mixed powder; the percentage is a mass percentage.

[0089] The graphite is expanded graphite; the adhesive is conductive polyaniline.

[0090] The upper mold of the mold is the cathode flow field of the electrode plate, and the lower mold of the mold is the anode flow field of the electrode plate.

[0091] The molding pore-forming material is molded polyvinyl alcohol.

[0092] The molded polyvinyl alcohol is prepared by the following method:

[0093] S11. Polyvinyl alcohol and water are mixed at a mass ratio of 1:20 and heated to 90°C to obtain a homogeneous solution; a crosslinking agent is added to the homogeneous solution, and stirring is continued until homogeneous to obtain a mixed solution; the mass of the crosslinking agent is 1% of the mass of the polyvinyl alcohol;

[0094] S12. Cool the mixed solution to room temperature to obtain a cooled mixed solution; introduce the cooled mixed solution into the electrode water surface flow field mold to obtain polyvinyl alcohol with a flow field shape;

[0095] S13. The polyvinyl alcohol with the flow field shape is dried at 40°C to obtain molded polyvinyl alcohol.

[0096] In step S11, the crosslinking agent is borax; the stirring time is 20 minutes. This ensures that the borax is evenly dispersed.

[0097] In step S02,

[0098] The pressurization pressure is 25 MPa; the pressurization time is 20 minutes. The heating is carried out in an inert gas; the inert gas is argon.

[0099] In step S03,

[0100] The vacuum pressure impregnation time is 5 hours; the vacuum pressure impregnation pressure is 0.5 MPa.

[0101] The rinsing process involves rinsing with clean water for 45 minutes.

[0102] The curing process involves curing in hot water at 95°C for 45 minutes.

[0103] The prepared integrated fuel cell bipolar plate was cut and then subjected to airtightness and related performance tests. The results showed that the airtightness of the integrated fuel cell was 0.13 sccm and the contact resistance was 4.2 mΩ·cm. 2 The conductivity is 353 S / cm, meaning that the integrated fuel cell bipolar plate obtained in this application meets the requirements for use of fuel cells and can satisfy the needs of fuel cell use.

[0104] Example 3

[0105] A method for fabricating an integrated fuel cell bipolar plate includes the following steps:

[0106] S01. The first mixed powder is evenly spread in the mold to obtain the first mixed powder layer; the forming and pore-forming material is evenly spread on the first mixed powder layer to obtain the forming and pore-forming material layer; the second mixed powder is evenly spread on the forming and pore-forming material layer to obtain the integrated electrode powder.

[0107] S02. At 150°C, the integrated electrode powder is pressurized and molded to obtain an integrated electrode; the integrated electrode is heated to 230°C and held for 3 hours to obtain an integrated bipolar plate with a cathode flow channel, an anode flow channel and a water flow channel.

[0108] S03. The integrated bipolar plate with cathode flow channel, anode flow channel and water flow channel is immersed in acrylic resin, impregnated under vacuum pressure, rinsed and then cured to obtain an integrated fuel cell bipolar plate.

[0109] In step S01,

[0110] Both the first mixed powder and the second mixed powder are graphite / adhesive mixed powders; the mass ratio of the first mixed powder to the second mixed powder is 1:1.

[0111] The graphite / adhesive mixed powder is prepared by the following method: 85% graphite and 15% adhesive are mixed evenly by dry powder spraying to obtain the graphite / adhesive mixed powder; the percentage is a mass percentage.

[0112] The graphite is expanded graphite; the adhesive is conductive polyaniline.

[0113] The upper mold of the mold is the cathode flow field of the electrode plate, and the lower mold of the mold is the anode flow field of the electrode plate.

[0114] The molding pore-forming material is molded polyvinyl alcohol.

[0115] The molded polyvinyl alcohol is prepared by the following method:

[0116] S11. Polyvinyl alcohol and water are mixed at a mass ratio of 1:15 and heated to 85°C to obtain a homogeneous solution; a crosslinking agent is added to the homogeneous solution and stirring is continued until homogeneous to obtain a mixed solution; the mass of the crosslinking agent is 2% of the mass of the polyvinyl alcohol;

[0117] S12. Cool the mixed solution to room temperature to obtain a cooled mixed solution; introduce the cooled mixed solution into the electrode water surface flow field mold to obtain polyvinyl alcohol with a flow field shape;

[0118] S13. The polyvinyl alcohol with the flow field shape is dried at 50°C to obtain molded polyvinyl alcohol.

[0119] In step S11, the crosslinking agent is borax; the stirring time is 30 minutes. This ensures that the borax is evenly dispersed.

[0120] In step S02,

[0121] The pressurization pressure is 28 MPa; the pressurization time is 18 minutes. The heating is carried out in an inert gas; the inert gas is argon.

[0122] In step S03,

[0123] The vacuum pressure impregnation time is 5 hours; the vacuum pressure impregnation pressure is 0.6 MPa.

[0124] The rinsing process involves rinsing with clean water for 60 minutes.

[0125] The curing process involves curing in hot water at 92°C for 60 minutes.

[0126] The fabricated integrated fuel cell bipolar plate was cut and then subjected to airtightness and related performance tests. The results showed that the airtightness of the integrated fuel cell was 0.14 sccm and the contact resistance was 4.3 mΩ·cm. 2The conductivity is 356 S / cm, meaning that the integrated fuel cell bipolar plate obtained in this application meets the requirements for use of fuel cells and can satisfy the needs of fuel cell use.

[0127] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for fabricating an integrated fuel cell bipolar plate, characterized in that, Includes the following steps: S01. The first mixed powder is evenly spread in the mold to obtain the first mixed powder layer; the forming and pore-forming material is evenly spread on the first mixed powder layer to obtain the forming and pore-forming material layer; the second mixed powder is evenly spread on the forming and pore-forming material layer to obtain the integrated electrode powder. S02. The integrated electrode powder is pressurized and molded at 140℃~160℃ to obtain an integrated electrode; the integrated electrode is heated to 200℃~230℃ and held for 2h~3h to obtain an integrated bipolar plate with a cathode flow channel, an anode flow channel and a water flow channel. S03. The integrated bipolar plate with cathode flow channel, anode flow channel and water flow channel is immersed in acrylic resin, impregnated under vacuum pressure, rinsed and then cured to obtain an integrated fuel cell bipolar plate. In step S01, both the first mixed powder and the second mixed powder are graphite / adhesive mixed powders; the mass ratio of the first mixed powder to the second mixed powder is 1:

1. The graphite / adhesive mixed powder is prepared by the following method: 75%–85% graphite and 15%–25% adhesive are mixed evenly by dry powder spraying to obtain the graphite / adhesive mixed powder; the percentages are by mass; the graphite is expanded graphite; the adhesive is conductive polyaniline; The molding pore-forming material is molded polyvinyl alcohol; the molded polyvinyl alcohol is prepared by the following method: S11. Polyvinyl alcohol and water are mixed at a mass ratio of 1:10 to 1:20 and heated to 80°C to 90°C to obtain a homogeneous solution; a crosslinking agent is added to the homogeneous solution, and stirring is continued until homogeneous to obtain a mixed solution; the mass of the crosslinking agent is 1% to 3% of the mass of the polyvinyl alcohol. S12. Cool the mixed solution to room temperature to obtain a cooled mixed solution; The cooling mixture is introduced into the electrode plate water surface flow field mold to obtain polyvinyl alcohol with a flow field shape; S13. The polyvinyl alcohol with the flow field shape is dried at 40℃~60℃ to obtain molded polyvinyl alcohol.

2. The method for preparing the integrated fuel cell bipolar plate according to claim 1, characterized in that, In step S01, the upper mold of the mold is the cathode flow field of the electrode plate, and the lower mold of the mold is the anode flow field of the electrode plate.

3. The method for preparing the integrated fuel cell bipolar plate according to claim 1, characterized in that, In step S11, The crosslinking agent is borax; the stirring time is 20 to 30 minutes.

4. The method for preparing the integrated fuel cell bipolar plate according to claim 1, characterized in that, In step S02, the pressurization pressure is 25-35 MPa; the pressurization time is 15-20 minutes; and the heating is carried out in an inert gas.

5. The method for preparing the integrated fuel cell bipolar plate according to claim 1, characterized in that, In step S03, the vacuum pressure impregnation time is 4 to 6 hours; the vacuum pressure impregnation pressure is 0.4 to 0.6 MPa.

6. The method for preparing the integrated fuel cell bipolar plate according to claim 1, characterized in that, In step S03, the rinsing is performed with clean water for 30 to 60 minutes; The curing process involves curing in hot water at 90–95°C for 30–60 minutes.

7. An integrated fuel cell bipolar plate, characterized in that, The integrated fuel cell bipolar plate is prepared by the preparation method described in any one of claims 1 to 6.