Manufacturing method of solid oxide fuel cell connecting plate

Abstract

The invention relates to a manufacturing method of a solid oxide fuel cell connecting plate, which comprises the following steps of: preparing a heat-resistant alloy plate which is a chromium-based alloy plate, a stainless steel plate or a nickel-based alloy plate by adopting a powder metallurgy method, the thickness of the heat-resistant alloy plate is 1-3mm, the porosity of the heat-resistant alloy plate is 5-20%, and the thickness of the heat-resistant alloy plate is 1-3 mm; the method comprises the following steps: soaking a heat-resistant alloy plate in a solution containing a hole sealing agent in a hole sealing agent infiltration manner, vacuumizing, keeping for 10 minutes, taking out the heat-resistant alloy plate, and drying to obtain the solid oxide fuel cell connecting plate, the hole sealing agent is a silicate base, a phosphate base, an inorganic ceramic base or a metal-ceramic composite base, and the hole sealing agent is a metal-ceramic composite base. And the size of the solid oxide fuel cell connecting plate is 100-250cm < 2 >. The large-size solid oxide fuel cell connecting plate prepared by the invention has few pores and good air tightness. Meanwhile, the hole sealing agent hinders inward diffusion of the oxidizing atmosphere, and the oxidation resistance of the connecting plate is greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of fuel cell technology, and specifically relates to a method for manufacturing a solid oxide fuel cell connection plate. Background Technology

[0002] Solid oxide fuel cells (SOFCs) are a highly efficient and clean energy conversion technology. Their core characteristics include high-temperature operation (600–1000℃), an all-solid-state structure (no liquid electrolyte), and fuel flexibility (they can directly utilize various fuels such as hydrogen, methane, and biogas). Their significant advantages include: 1. Ultra-high efficiency: power generation efficiency of 50–65%, and combined heat and power (CHP) efficiency exceeding 80%; 2. Environmentally friendly: zero harmful emissions, producing only water and carbon dioxide; 3. Long lifespan and low degradation: ceramic materials are high-temperature resistant, with a degradation rate of <0.5% / 1000 hours; 4. Versatile application: suitable for distributed power generation, industrial waste energy utilization, and hydrogen electrolysis. SOFCs combine high energy efficiency with low carbon emissions, making them a key technology for future sustainable energy systems.

[0003] In solid oxide fuel cells, the connecting plate is a core component supporting the stable operation of the fuel cell stack. It mainly plays the following key roles: 1. Electrical connection: connecting the anode and cathode of adjacent single cells in series to form a complete circuit, ensuring that electrons flow from the anode to the cathode through the external circuit; 2. Gas isolation: preventing the fuel (H2 / CH4) from directly mixing with the oxidant (air), avoiding energy loss or explosion risks. The surface is processed with microchannels (such as serpentine / parallel channels) to evenly distribute gas to the electrode active area; 3. Mechanical support: supporting the brittle ceramic electrolyte and electrode layer and resisting the assembly pressure of the fuel cell stack.

[0004] In solid oxide fuel cells (SOFCs), the airtightness of the connecting plates is a key factor in ensuring the efficient, stable, and safe operation of the fuel stack, directly affecting battery performance, lifespan, and system reliability. Its importance is mainly reflected in the following aspects: 1. Preventing cross-mixing of fuel and oxidant: If fuel (H2 / CH4) and oxidant (O2 / air) come into direct contact, a combustion reaction will occur instead of an electrochemical reaction, leading to a significant decrease in energy efficiency; 2. Reducing polarization losses: Gas cross-contamination alters the local atmosphere of the electrodes, increasing concentration polarization and affecting battery voltage stability; 3. Extending fuel stack lifespan: Fuel leakage to the air side may cause repeated oxidation / reduction of the Ni-based anode, inducing microcracks. Gas leakage also accelerates the aging or cracking of sealing materials (such as glass-ceramics).

[0005] In recent years, in order to improve the power density of SOFC systems, the area of ​​the designed single cells has been continuously increasing, which has placed higher demands on the fabrication processes of various components, including the fabrication of large-size interconnect plates. Fabricating large-size interconnect plates using powder metallurgy requires a large tonnage for pressing, but due to the limitations of existing press tonnage, the pressing density cannot reach the ideal level, and the density after sintering may not meet the airtightness requirements. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a method for manufacturing a large-size solid oxide fuel cell connecting plate, in order to improve the airtightness of the connecting plate, in view of the current status of the prior art.

[0007] The technical solution adopted by the present invention to solve the above-mentioned technical problems is: a method for manufacturing a solid oxide fuel cell connection plate, characterized by the following steps: A heat-resistant alloy plate is prepared using powder metallurgy. The heat-resistant alloy plate is a chromium-based alloy plate, a stainless steel plate, or a nickel-based alloy plate. The thickness of the heat-resistant alloy plate is 1-3 mm, and the porosity is 5-20%. The heat-resistant alloy plate is immersed in a solution containing a sealing agent by impregnation. After vacuuming and maintaining this state for 10 minutes, the heat-resistant alloy plate is removed and dried to obtain a solid oxide fuel cell connection plate. The sealing agent is silicate-based, phosphate-based, inorganic ceramic-based, or metal-ceramic composite-based. The size of the solid oxide fuel cell connection plate is 100-250 cm². 2 .

[0008] The dimensions mentioned above refer to the area of ​​a single surface of the connecting plate.

[0009] The solid oxide fuel cell connecting plate obtained by impregnating a heat-resistant alloy plate with a sealing agent has few pores and good airtightness. At the same time, the sealing agent hinders the inward diffusion of oxidizing atmosphere, significantly improving the oxidation resistance of the connecting plate.

[0010] Preferably, in the powder metallurgy method, the particle size of the powder used is -1000 to -60 mesh, the pressing pressure of the molding process is 500 to 1500 MPa, the sintering temperature is 1100 to 1600℃, the holding time is 0.5 to 4 hours, and the sintering atmosphere is a vacuum or argon protection.

[0011] Preferably, the process of impregnating the sealing agent can be repeated, and the heat-resistant alloy plate must be removed and dried after each impregnation. This allows the number of impregnation cycles to be selected based on the impregnation effect of different sealing agents.

[0012] In the above scheme, preferably, after the heat-resistant alloy plate is removed and dried, the internal pores of the heat-resistant alloy plate are selectively filled using an oxidation sealing process, and then the surface oxide layer is removed by sandblasting, thus obtaining the solid oxide fuel cell connection plate. This further reduces the porosity of the connection plate and improves its airtightness.

[0013] Furthermore, sandblasting can simultaneously remove any residual sealant from the surface.

[0014] Furthermore, the oxidation sealing process is as follows: oxidation is carried out in an air or oxygen atmosphere at an oxidation temperature of 800~1100℃ for 1~120h.

[0015] Preferably, the solid oxide fuel cell connection plate has a leakage rate ≤ 5 mL / min (2.75 bar, 20°C), a bending strength ≥ 300 MPa (20°C), and an oxidation weight gain ≤ 5 mg / cm³. 2 (800℃, per thousand hours).

[0016] Compared with the prior art, the advantages of the present invention are as follows: the solid oxide fuel cell connecting plate obtained by impregnating the heat-resistant alloy plate with a sealing agent has fewer pores and better airtightness. At the same time, the sealing agent hinders the inward diffusion of oxidizing atmosphere, greatly improving the oxidation resistance of the connecting plate. Attached Figure Description

[0017] Figure 1 This is a cross-sectional microscope image of the heat-resistant alloy plate after sodium silicate impregnation in Example 1 of the present invention; Figure 2 This is a cross-sectional microscope image of the heat-resistant alloy plate after oxidation sealing in Embodiment 1 of the present invention. Detailed Implementation

[0018] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Example 1:

[0019] A method for manufacturing a solid oxide fuel cell connection plate includes the following steps: Step 1: Prepare Cr5Fe heat-resistant alloy plates using powder metallurgy. The powder particle size was selected as -100 mesh, the pressing pressure was 900 MPa, and sintering was carried out under vacuum reverse argon protection at a temperature of 1450℃ for 2 hours. The thickness of the sintered heat-resistant alloy plate was approximately 2.5 mm, and the porosity was approximately 10%. Step 2: Immerse the sintered heat-resistant alloy plate in a sodium silicate aqueous solution (50% deionized water), evacuate to -95 kPa and maintain for 10 min, then immediately remove and dry at 90°C for 30 min; repeat the above steps three times. Microscopic images of the cross-section of the immersed heat-resistant alloy plate are shown below. Figure 1 As shown; Step 3: The impregnated heat-resistant alloy plate is oxidized at 1050℃ for 10 hours in air. The microscopic cross-sectional image of the oxidized and sealed heat-resistant alloy plate is shown below. Figure 2 As shown; Step 4: Sandblast the surface of the oxidized and sealed heat-resistant alloy plate with -120 mesh white corundum to remove the surface oxide layer and residual sodium silicate, thus obtaining the solid oxide fuel cell connection plate.

[0020] The solid oxide fuel cell connection plate fabricated in this embodiment has a size of 180cm. 2 It has few pores. Specific performance parameters are: leakage rate ≤5mL / min (2.75bar, 20℃), flexural strength 310MPa (20℃), and oxidative weight gain 0.3mg / cm³. 2 (800℃, per thousand hours). Example 2:

[0021] A method for manufacturing a solid oxide fuel cell connection plate includes the following steps: Step 1: Prepare Cr5Fe heat-resistant alloy plates using powder metallurgy. The powder particle size was selected as -100 mesh, the pressing pressure was 800 MPa, and sintering was carried out under vacuum reverse argon protection at a temperature of 1450℃ for 2 hours. The thickness of the sintered heat-resistant alloy plate was approximately 2.8 mm, and the porosity was approximately 12%. Step 2: Immerse the sintered heat-resistant alloy plate in a sol-gel (30% aluminum sol, 2% silane coupling agent, balance ethanol), vacuum to -0.1MPa and hold for 10 min, then immediately remove it and dry at 80℃ for 30 min, and then sinter at 600℃ for 1 h. Step 3: The heat-resistant alloy plate after impregnation and sintering is oxidized at 1050℃ for 10 hours in air atmosphere; Step 4: Sandblast the surface of the oxidized and sealed heat-resistant alloy plate with -120 mesh white corundum to remove the surface oxide layer and residual aluminum oxide, thus obtaining the solid oxide fuel cell connection plate.

[0022] The solid oxide fuel cell connection plate fabricated in this embodiment has a size of 150cm. 2 It has few pores. Specific performance parameters are: leakage rate ≤3mL / min (2.75bar, 0℃), flexural strength 310MPa (20℃), and oxidative weight gain 0.2mg / cm³. 2 (800℃, per thousand hours). Example 3:

[0023] A method for manufacturing a solid oxide fuel cell connection plate includes the following steps: Step 1: Prepare heat-resistant alloy plates of 430 stainless steel using powder metallurgy: The powder particle size was selected as -100 mesh, the pressing pressure was 500 MPa, and sintering was carried out under vacuum reverse argon protection at a temperature of 1250℃ for 1 hour. The thickness of the sintered heat-resistant alloy plate was approximately 2.5 mm, and the porosity was approximately 5%. Step 2: Immerse the sintered heat-resistant alloy plate in an aqueous solution of aluminum phosphate (50% Al(H2PO4)3, 30% ZrSiO4, and the remainder deionized water), evacuate to -0.1MPa and hold for 10 minutes, then immediately remove it and cure at 120℃ for 1 hour, and then keep it at 400℃ for 1 hour. Step 3: Sandblast the surface of the impregnated heat-resistant alloy plate with -120 mesh white corundum to remove the residual aluminum phosphate-based sealing agent on the surface, thus obtaining the solid oxide fuel cell connection plate.

[0024] The solid oxide fuel cell connection plate fabricated in this embodiment has a size of 120cm. 2 It has few pores. Furthermore, the solid oxide fuel cell connection plate underwent an airtightness test at 3 bar pressure, with a gas leakage of <1 mL / min. Specific performance parameters are: leakage rate ≤0.5 mL / min (2.75 bar, 20℃), flexural strength 400 MPa (20℃), and oxidation weight gain 5 mg / cm³. 2 (800℃, per thousand hours). Comparative Example 1:

[0025] The Cr5Fe heat-resistant alloy plate prepared in step 1 of Example 1 was used as the connection plate for the solid oxide fuel cell. The performance parameters of the connection plate were: leakage rate > 10 mL / min (2.75 bar, 20℃), bending strength 300 MPa (20℃), and oxidation weight gain 3 mg / cm³. 2 (800℃, per thousand hours). Comparative Example 2:

[0026] The Cr5Fe heat-resistant alloy plate prepared in step 1 of Example 1 was oxidized at 1050℃ for 10 hours in air. Then, the surface of the oxidized heat-resistant alloy plate was sandblasted with -120 mesh white corundum to remove the surface oxide layer, thus obtaining the solid oxide fuel cell connection plate. The performance parameters of this connection plate are: leakage rate <10mL / min (2.75bar, 20℃), bending strength 290MPa (20℃), and oxidation weight gain 1mg / cm³. 2 (800℃, per thousand hours). Comparative Example 3:

[0027] The heat-resistant alloy plate made of 430 stainless steel prepared in step 1 of Example 3 was used as the connection plate for the solid oxide fuel cell. The performance parameters of the connection plate were: leakage rate ≤1mL / min (2.75bar, 20℃), bending strength 400MPa (20℃), and oxidation weight gain 10mg / cm³. 2 (800℃, per thousand hours).

Claims

1. A method for manufacturing a solid oxide fuel cell connection plate, characterized in that... The steps are as follows: A heat-resistant alloy plate is prepared using powder metallurgy. The heat-resistant alloy plate is a chromium-based alloy plate, a stainless steel plate, or a nickel-based alloy plate. The thickness of the heat-resistant alloy plate is 1-3 mm, and the porosity is 5-20%. The heat-resistant alloy plate is immersed in a solution containing a sealing agent by impregnation. After vacuuming and maintaining this state for 10 minutes, the heat-resistant alloy plate is removed and dried to obtain a solid oxide fuel cell connection plate. The sealing agent is silicate-based, phosphate-based, inorganic ceramic-based, or metal-ceramic composite-based. The size of the solid oxide fuel cell connection plate is 100-250 cm². 2 .

2. The manufacturing method according to claim 1, characterized in that: In powder metallurgy, the particle size of the powder used is -1000 to -60 mesh, the pressing pressure of the molding process is 500 to 1500 MPa, the sintering temperature is 1100 to 1600℃, the holding time is 0.5 to 4 hours, and the sintering atmosphere is a vacuum or argon protection.

3. The manufacturing method according to claim 1, characterized in that: The process of impregnating the sealing agent can be repeated, and the heat-resistant alloy plate must be removed and dried after each impregnation.

4. The manufacturing method according to claim 1, characterized in that: After the heat-resistant alloy plate is removed and dried, the internal pores of the heat-resistant alloy plate are selectively filled by an oxidation sealing process. Then, the surface oxide layer is removed by sandblasting to obtain the solid oxide fuel cell connection plate.

5. The manufacturing method according to claim 4, characterized in that: Sandblasting can remove residual sealant from the surface at the same time.

6. The manufacturing method according to claim 4, characterized in that: The oxidation sealing process is as follows: oxidation is carried out in an air or oxygen atmosphere at a temperature of 800~1100℃ for 1~120h.

7. The manufacturing method according to any one of claims 1 to 6, characterized in that: The solid oxide fuel cell connection plate has a leakage rate ≤5mL / min, a bending strength ≥300MPa, and an oxidation weight gain ≤5mg / cm³. 2 .

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