Preparation method of fuel cell cathode plate capable of resisting cathode poisoning

Abstract

The invention relates to a preparation method of a fuel cell cathode plate capable of resisting cathode poisoning, and belongs to the technical field of fuel cells. The method comprises the following steps: obtaining an iron-based substrate with set chemical components and a first set thickness; the nickel-based substrate with the second set thickness is obtained; the iron-based substrate and the nickel-based substrate are subjected to coping and degreasing treatment, and the surface roughness of the iron-based substrate and the surface roughness of the nickel-based substrate are controlled; the degreased iron-based substrate and the degreased nickel-based substrate are subjected to cold composite rolling, and a composite strip is obtained; and the composite strip is sequentially subjected to annealing, trimming and sizing and runner machining, and the negative plate is obtained. The cathode plate has stable electrochemical performance and a low ASR value at a high temperature, less Cr-containing substances are deposited on the cathode, and the high requirement of the fuel cell on the cathode material can be met.

Description

Technical Field

[0001] The present application relates to the technical field of fuel cells, and in particular to a method for preparing a cathode plate of a fuel cell that is resistant to cathode poisoning. Background Art

[0002] High-temperature solid oxide fuel cell (SOFC) is a highly efficient energy conversion device that can directly convert the chemical energy of fuel into electrical energy at a high temperature of 800°C. It can directly use carbon-containing gases such as methane, natural gas and water gas as fuel. With the continuous improvement of material manufacturing processes and design technologies, the operating temperature of SOFC has been reduced from the traditional 1000°C to a medium temperature range of 600-800°C. This change makes it possible to use metal connector materials because metal connectors can meet the basic requirements of electrical conductivity, thermal expansion coefficient, thermal conductivity and oxidation resistance within this operating temperature range. At present, the four types of ferritic stainless steel connectors that have been studied more carefully are Crofer 22APU, SUS430, X10CrAl18 and ZMG232.

[0003] Although the above alloys have excellent performance, there are still bottlenecks in their commercial use, and they cannot currently meet the requirements of long-term operation of SOFC cell stacks. The main problem is that Cr-containing alloys will form volatile gaseous substances in an oxidizing environment. These volatile substances will be deposited on the cathode surface, seriously damaging the electrochemical properties of SOFC, that is, the cathode poisoning problem. At present, commercial alloys generally use the method of coating the cathode to solve the problem of cathode poisoning. However, this method increases the production process, prolongs the production preparation process, increases processing costs, and may lead to reduced production efficiency. In addition, the coating process may also be accompanied by problems such as environmental pollution. Summary of the invention

[0004] The present application provides a method for preparing a cathode plate of a fuel cell that is resistant to cathode poisoning, in order to solve the following technical problem: how to solve the cathode poisoning problem of the existing fuel cell cathode plate caused by Cr volatilization at 600° C. to 900° C.

[0005] The present application provides a method for preparing a cathode plate of a fuel cell that is resistant to cathode poisoning, the method comprising:

[0006] Obtaining an iron-based substrate having a set chemical composition and a first set thickness;

[0007] Obtaining a nickel-based substrate having a second set thickness;

[0008] Grinding and degreasing the iron-based substrate and the nickel-based substrate, and controlling the surface roughness of the iron-based substrate and the nickel-based substrate;

[0009] Cold composite rolling the degreased iron-based substrate and the nickel-based substrate to obtain a composite strip;

[0010] The composite strip is sequentially subjected to annealing, trimming and sizing, and flow channel machining to obtain a cathode plate.

[0011] Optionally, the deformation amount of a single pass of the cold composite rolling is 40% to 75%.

[0012] Optionally, the annealing temperature is 270°C to 350°C, the annealing holding time is 1h to 5h, and the annealing hydrogen injection volume is ≥ 20m 3 / h.

[0013] Optionally, the surface roughness of the iron-based substrate is 80 μm to 120 μm.

[0014] Optionally, the surface roughness of the nickel-based substrate is 50 μm to 80 μm.

[0015] Optionally, the set chemical composition includes, by mass fraction: Cr: 20% to 25%, Nb: 0.2% to 1.0%, W: 1% to 3%, Si: 0.15% to 0.3%, Mn: 0.1% to 0.8%, Al: 0.15% to 0.4%, C+N≤0.010%, O≤0.0020%, and matrix element Fe; wherein C+N represents the sum of the mass fractions of C and N.

[0016] Optionally, the first set thickness is 2 mm to 7 mm.

[0017] Optionally, the chemical composition of the nickel-based substrate includes, by mass fraction: Ni≥99.5%.

[0018] Optionally, the second set thickness satisfies the following relationship: 0.1mm≥h*ka≥0.01mm;

[0019] Wherein, h represents the second set thickness of the nickel-based substrate, k represents the deformation rate of the nickel-based substrate during the cold composite rolling process, and a represents the processing depth of the runner machining.

[0020] Optionally, in an O2-H2O atmosphere, after the cathode plate is oxidized at 600°C to 900°C for 40,000 hours, ASR ≤ 0.015Ω·cm 2 .

[0021] Optionally, the cathode plate is at a temperature above 900°C, when passing 400mA / cm 2 After 4000h of polarization with a current of 10000, the Cr-containing substances deposited at the cathode are ≤0.05mg / cm 2 .

[0022] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0023] The embodiment of the present application provides a method for preparing a cathode plate of a fuel cell that is resistant to cathode poisoning, the method comprising: obtaining an iron-based substrate having a set chemical composition and a first set thickness; obtaining a nickel-based substrate having a second set thickness; performing grinding and degreasing treatment on the iron-based substrate and the nickel-based substrate, and controlling the surface roughness of the iron-based substrate and the nickel-based substrate; performing cold composite rolling on the degreased iron-based substrate and the nickel-based substrate to obtain a composite strip; performing annealing, trimming and sizing, and flow channel machining on the composite strip in sequence to obtain a cathode plate. By performing cold composite rolling on the iron-based substrate and the nickel-based substrate, controlling the rolling parameters, the surface hardening layer of the metal material to be composited is broken under a large rolling force and welded under a large pressure, and the metal atoms are fully diffused by annealing to achieve a strong metallurgical bond, thereby achieving a layer of Ni metal composite on the cathode side of the solid oxide fuel cell substrate, and avoiding the poisoning of the battery cathode plate. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0026] Figure 1 A schematic flow chart of a method for preparing a cathode plate of a fuel cell that is resistant to cathode poisoning provided in an embodiment of the present application. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0028] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be understood as a rigid limitation on the scope of the present application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within the range; for example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which applies regardless of the range; in addition, whenever a numerical range is indicated in this document, it is meant to include any cited numbers (fractions or integers) within the indicated range.

[0029] In this document, the terms including "including" and "including" mean "including but not limited to". Relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. "And / or" describes the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone; where A and B can be singular or plural. "At least one" means one or more, and "plurality" means two or more; "at least one", "at least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items; for example, "at least one of a, b, or c", or "at least one of a, b, and c" can all mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple. "Parts" such as parts by weight and parts by mass indicate the proportional relationship between the components. In the proportional relationship involved in this article, the parameters that need to be described by proportion should be understood as the first term of the proportional formula in the order of description, and the proportional numbers should be understood as the second term of the proportional formula. For example, if the mass ratio of substance A, substance B and substance C is 1:2:3, then substance A, substance B and substance C should correspond to the proportional numbers in the proportional formula in the order of description, that is, the mass of substance A: the mass of substance B: the mass of substance C = 1:2:3.

[0030] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this article can be purchased from the market or prepared by existing methods.

[0031] Figure 1 A schematic flow chart of a method for preparing a cathode plate of a fuel cell that is resistant to cathode poisoning provided in an embodiment of the present application.

[0032] like Figure 1 As shown, the embodiment of the present application provides a method for preparing a cathode plate of a fuel cell that is resistant to cathode poisoning, the method comprising:

[0033] S1, obtaining an iron-based substrate having a set chemical composition and a first set thickness;

[0034] In some embodiments, the set chemical composition includes, by mass fraction: Cr: 20% to 25%, Nb: 0.2% to 1.0%, W: 1% to 3%, Si: 0.15% to 0.3%, Mn: 0.1% to 0.8%, Al: 0.15% to 0.4%, C+N≤0.010%, O≤0.0020%, and matrix element Fe; wherein C+N represents the sum of the mass fractions of C and N.

[0035] As a common conductive material, the control of chemical composition during the preparation of iron-based substrates is crucial. In addition to the main iron element, an appropriate amount of alloying elements, such as chromium, are also added. Among them, chromium can improve the corrosion resistance of the substrate. The amount and proportion of alloying elements added need to be precisely controlled according to actual needs to ensure that the substrate has sufficient corrosion resistance and mechanical strength while meeting the conductivity.

[0036] In some embodiments, the first set thickness is 2 mm to 7 mm.

[0037] The thickness of the iron-based substrate needs to be determined according to the design requirements of the fuel cell. During the preparation process, hot rolling, cold rolling, annealing and other process methods are required to ensure that the substrate reaches the required thickness requirements.

[0038] S2, obtaining a nickel-based substrate having a second set thickness;

[0039] The thickness of the nickel-based substrate is related to the subsequent processing parameters and needs to be determined based on the subsequent processing parameters.

[0040] In some embodiments, the chemical composition of the nickel-based substrate includes, by mass fraction: Ni≥99.5%.

[0041] This means that the nickel-based substrate is mainly composed of nickel, and the nickel content is extremely high, which is usually called high-purity nickel or pure nickel substrate. High-purity nickel substrate has excellent electrical conductivity, thermal conductivity and corrosion resistance.

[0042] In some embodiments, the second set thickness satisfies the following relationship: 0.1 mm ≥ h*ka ≥ 0.01 mm;

[0043] Wherein, h represents the second set thickness of the nickel-based substrate, k represents the deformation rate of the nickel-based substrate during the cold composite rolling process, and a represents the processing depth of the runner machining.

[0044] Deformation rate k: During the cold composite rolling process, the nickel-based substrate will deform to a certain extent. The deformation rate k is a parameter used to describe the degree of deformation, which is equal to the ratio of the deformed size to the original size.

[0045] The processing depth a of flow channel machining: refers to the depth of the channel on the cathode plate for gas flow, which affects the gas flow efficiency and battery performance.

[0046] S3, grinding and degreasing the iron-based substrate and the nickel-based substrate, and controlling the surface roughness of the iron-based substrate and the nickel-based substrate;

[0047] Before cold composite rolling, it is crucial to grind and degrease the substrate. The grinding process can penetrate into the surface of the substrate, remove defects, impurities and pollutants that affect the surface flatness and quality, make the substrate surface smoother and flatter, and ensure the smooth progress of subsequent processes. The degreasing process is mainly to thoroughly remove organic matter such as grease, lubricating oil, and rust-proof oil attached to the surface of the substrate by chemical or physical methods, exposing a clean metal matrix to ensure good wettability and bonding between the substrate and another metal material during the cold composite rolling process. In the embodiment of the present application, grinding methods such as grinding wheels can be used to grind iron-based substrates and nickel-based substrates, and degreasing agents such as anhydrous ethanol can be used to degrease and clean the surfaces of iron-based substrates and nickel-based substrates.

[0048] In some embodiments, the surface roughness of the iron-based substrate is 80 μm to 120 μm.

[0049] In some embodiments, the surface roughness of the nickel-based substrate is 50 μm to 80 μm.

[0050] S4, cold composite rolling the degreased iron-based substrate and the nickel-based substrate to obtain a composite strip;

[0051] Cold composite rolling is a rolling process carried out at room temperature, which can combine two or more metal materials together through a rolling process to form a composite material. This method can accurately control the thickness, composition and microstructure of the composite material, thereby optimizing its performance. Through the cold composite rolling method, composite materials with excellent oxidation resistance and electrical conductivity can be prepared, which can be used as cathodes or cathode coatings for SOFCs. During the cold composite rolling process, parameters such as rolling force, rolling speed and temperature need to be precisely controlled to ensure a good metallurgical bond between the two substrates while avoiding cracks and defects. In the embodiment of the present application, the yield rate of the composite strip is ≥85%, and the production efficiency of the composite strip is 100kg / h to 300kg / h.

[0052] In some embodiments, the deformation amount of a single pass of the cold composite rolling is 40% to 75%.

[0053] The bonding strength of the metal composite strip increases with the deformation amount, and the deformation heat increases, which leads to an increase in the number of activated metal atoms and an increase in the bonding strength of the composite strip; however, due to the special properties of the ferrite structure of the iron-based substrate, the grain boundary bonding force is weak, and excessive deformation will cause the ferrite substrate to crack. Therefore, the embodiment of the present application limits the single-pass deformation amount to 40% to 75%. If the deformation amount is less than 40%, rolling failure will occur; if the deformation amount is higher than 75%, the risk of cracking of the iron-based substrate increases. Exemplarily, the single-pass deformation amount of cold composite rolling can be 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, etc.

[0054] S5, annealing, trimming and sizing the composite strip in sequence, and processing the flow channel by a machine to obtain a cathode plate.

[0055] After the cold composite rolling process, the composite substrate needs to undergo a series of post-processing operations to ensure that it meets the quality requirements of the final product - the cathode plate. Cold composite rolling forms local rolling welds between the two substrates, mainly mechanical interlocking, while diffusion annealing starts new bonding points, allowing the atoms of the entire contact surface to penetrate each other. Next, according to the specific size requirements and design specifications of the cathode plate, the composite substrate is precisely trimmed and sized. This step is designed to remove excess parts, accurately control the dimensional accuracy of the cathode plate, ensure its good fit with the overall assembly and other components, and meet the various technical standards for the operation of the fuel cell system. Finally, a complex flow channel system is finely engraved on the cathode plate through flow channel machining technology. These flow channels are key components for the normal operation of fuel cells. They are responsible for evenly distributing the reaction gas to every corner of the battery, ensuring that the battery surface is fully contacted and chemical reactions occur.

[0056] In some embodiments, the annealing temperature is 270°C to 350°C, the annealing holding time is 1h to 5h, and the annealing hydrogen injection volume is ≥ 20m 3 / h.

[0057] The annealing temperature is lower than 270°C, which is insufficient to achieve the effect of complete diffusion and penetration; the annealing temperature is higher than 350°C, which will lead to the precipitation of brittle phase. Exemplarily, the annealing temperature can be 270°C, 280°C, 290°C, 300°C, 310°C, 320°C, 330°C, 340°C, 350°C, etc.

[0058] Hydrogen injection can protect the material from oxidation during annealing and help control the atmosphere in the furnace. For example, the annealing hydrogen injection rate is 20m3 / h, 22m 3 / h、24m 3 / h、26m 3 / h、28m 3 / h、30m 3 / h, etc.

[0059] In the embodiment of the present application, a box-type furnace is used for annealing. The box-type furnace has a compact structure and is easy to operate, and is suitable for annealing of various materials. By adjusting parameters such as the amount of hydrogen sprayed, the atmosphere in the furnace can be accurately controlled to ensure the consistency of the annealing effect. The box-type furnace usually has a higher thermal efficiency and lower energy consumption, which is conducive to reducing production costs.

[0060] In some embodiments, after the cathode plate is oxidized at 600°C to 900°C for 40,000 hours in an O2-H2O atmosphere, ASR is ≤ 0.015Ω·cm 2 .

[0061] In the fuel cell system, the cathode plate is an important carrier of gas diffusion and electrochemical reaction. The quality of its conductive performance directly affects the efficiency of the entire battery system. ASR (area specific resistance) is an indicator to measure the conductivity of a material. The smaller the ASR, the better the conductivity of the material. In the embodiment of the present application, after the cathode plate is oxidized at 600℃~900℃ for 40000h, ASR≤0.015Ω·cm 2 ,This result indicates that the cathode plate maintains good conductivity for a long time in high temperature and oxidative environment.

[0062] In some embodiments, the cathode plate is at a temperature above 900°C when passing 400 mA / cm 2 After 4000h of polarization with a current of 10000, the Cr-containing substances deposited at the cathode are ≤0.05mg / cm 2 .

[0063] The evaluation of cathode deposition after high-temperature polarization is a key indicator for evaluating cathode plate performance. During actual operation, the fuel cell may produce electrode polarization under high temperature and polarization conditions, resulting in the formation of deposits on the surface of the cathode plate. The composition of these deposits is complex and may include metal oxides, hydroxides and other chemical products. The presence of deposits not only occupies valuable reaction area, but may also change the physical and chemical properties of the cathode plate, such as reducing the gas diffusion rate and increasing the internal resistance of the electrode. Therefore, it is necessary to evaluate the type and amount of deposits on the cathode plate after high-temperature polarization. In the embodiment of the present application, the cathode plate is at a temperature above 900°C, when passing through 400mA / cm 2 After 4000h of polarization with a current of 10000, the Cr-containing substances deposited at the cathode are ≤0.05mg / cm 2 This result shows that the cathode plate has good resistance to Cr volatilization under high temperature and current.

[0064] The preparation method provided in this application ensures that the cathode plate obtained finally has excellent anti-cathode poisoning performance by precisely controlling the chemical composition, thickness, surface roughness of the iron-based and nickel-based substrates, as well as process parameters such as cold composite rolling and annealing. This not only improves the efficiency and life of the fuel cell, but also provides technical support for its application in a wider range of fields.

[0065] The present application is further described below in conjunction with specific examples. The experimental methods in the following examples where specific conditions are not specified are usually measured in accordance with national standards / industry standards; if there are no corresponding national standards / industry standards, they are measured in accordance with common international standards, conventional conditions or conditions recommended by the manufacturer.

[0066] Example 1

[0067] An iron-based substrate with a thickness of 5 mm was obtained, and the chemical composition of the iron-based substrate included: Cr: 22%, Nb: 0.5%, W: 1%, Si: 0.1%, Mn: 0.1%, Al: 0.2%, C+N≤0.010%, O: 0.0018%, and the rest was Fe.

[0068] The thickness of the nickel-based substrate is 1 mm; after the iron-based substrate and the nickel-based substrate are ground and degreased, the surface roughness of the iron-based substrate is 80 μm, and the surface roughness of the nickel-based substrate is 50 μm.

[0069] The deformation of a single pass of cold composite rolling is 50%, the yield rate of composite strip is 88%, and the production efficiency of composite strip is 150kg / h.

[0070] The annealing was carried out in a box furnace at a temperature of 300°C, a holding time of 2 hours, and a hydrogen injection volume of 20 m 3 / h.

[0071] Trim the edges and determine the length to 2 meters.

[0072] The flow channel machining is performed on the nickel layer side of the composite strip, and the depth of the cathode plate gas flow channel groove is 0.4mm.

[0073] The obtained solid oxide fuel cell cathode plate performance:

[0074] Conductivity index: In O2-H2O atmosphere, oxidized at 600℃~900℃ for 40000h, ASR is 0.015Ω·cm 2 .

[0075] Cathode Cr volatilization index: cathode plate above 900℃, 400mA / cm 2 Current polarization for 4000h, cathode deposition of Cr-containing substances is 0.05mg / cm 2 .

[0076] Example 2

[0077] An iron-based substrate with a thickness of 2.5 mm was obtained, and the chemical composition of the iron-based substrate included: Cr: 22%, Nb: 0.5%, W: 1%, Si: 0.1%, Mn: 0.1%, Al: 0.2%, C+N≤0.010%, O: 0.0018%, and the rest was Fe.

[0078] The thickness of the nickel-based substrate is 0.5 mm; after the iron-based substrate and the nickel-based substrate are ground and degreased, the surface roughness of the iron-based substrate is 80 μm, and the surface roughness of the nickel-based substrate is 50 μm.

[0079] The deformation of a single pass of cold composite rolling is 75%, the yield rate of composite strip is 85%, and the production efficiency of composite strip is 100kg / h.

[0080] The annealing was carried out in a box furnace at a temperature of 320°C, a holding time of 1 h, and a hydrogen injection volume of 20 m 3 / h.

[0081] Trim the edges and determine the length to 2 meters.

[0082] The flow channel machining is performed on the nickel layer side of the composite strip, and the depth of the cathode plate gas flow channel groove is 0.1mm.

[0083] The obtained solid oxide fuel cell cathode plate performance:

[0084] Conductivity index: In O2-H2O atmosphere, 600℃~900℃ oxidation for 40000h, ASR is 0.013Ω·cm 2 .

[0085] Cathode Cr volatilization index: cathode plate above 900℃, 400mA / cm 2 Current polarization for 4000h, cathode deposition of Cr-containing substances is 0.04mg / cm 2 .

[0086] Comparative Example 1

[0087] An iron-based substrate with a thickness of 2.5 mm was obtained, and the chemical composition of the iron-based substrate included: Cr: 22%, Nb: 0.5%, W: 1%, Si: 0.1%, Mn: 0.1%, Al: 0.2%, C+N≤0.010%, O: 0.0018%, and the rest was Fe.

[0088] The annealing was carried out in a box furnace at a temperature of 320°C, a holding time of 1 h, and a hydrogen injection volume of 20 m 3 / h.

[0089] Trim the edges and determine the length to 2 meters.

[0090] The flow channel is machined to a depth of 0.1 mm for the gas flow channel groove of the cathode plate.

[0091] The obtained solid oxide fuel cell cathode plate performance:

[0092] Conductivity index: In O2-H2O atmosphere, oxidized at 600℃~900℃ for 40000h, ASR is 0.5Ω·cm 2 .

[0093] Cathode Cr volatilization index: cathode plate above 900℃, 400mA / cm 2 Current polarization for 4000h, cathode deposition of Cr-containing substances is 0.2mg / cm 2 .

[0094] Comparative Example 2

[0095] An iron-based substrate with a thickness of 5 mm was obtained, and the chemical composition of the iron-based substrate included: Cr: 22%, Nb: 0.5%, W: 1%, Si: 0.1%, Mn: 0.1%, Al: 0.2%, C+N≤0.010%, O: 0.0018%, and the rest was Fe.

[0096] The thickness of the nickel-based substrate is 1 mm; after the iron-based substrate and the nickel-based substrate are ground and degreased, the surface roughness of the iron-based substrate is 80 μm, and the surface roughness of the nickel-based substrate is 50 μm.

[0097] The deformation of a single pass of cold composite rolling is 35%.

[0098] The annealing was carried out in a box furnace at a temperature of 300°C, a holding time of 2 hours, and a hydrogen injection volume of 20 m 3 / h.

[0099] Trim the edges and determine the length to 2 meters.

[0100] The flow channel machining is performed on the nickel layer side of the composite strip, and the depth of the cathode plate gas flow channel groove is 0.4mm.

[0101] The composite nickel layer cracked and composite rolling failed.

[0102] Comparative Example 3

[0103] An iron-based substrate with a thickness of 5 mm was obtained, and the chemical composition of the iron-based substrate included: Cr: 22%, Nb: 0.5%, W: 1%, Si: 0.1%, Mn: 0.1%, Al: 0.2%, C+N≤0.010%, O: 0.0018%, and the rest was Fe.

[0104] The thickness of the nickel-based substrate is 1 mm; after the iron-based substrate and the nickel-based substrate are ground and degreased, the surface roughness of the iron-based substrate is 80 μm, and the surface roughness of the nickel-based substrate is 50 μm.

[0105] The deformation of a single pass of cold composite rolling is 70%.

[0106] Annealing was carried out in a box furnace at a temperature of 400°C, a holding time of 2 hours, and a hydrogen injection volume of 20 m 3 / h.

[0107] Trim the edges and determine the length to 2 meters.

[0108] The flow channel machining is performed on the nickel layer side of the composite strip, and the depth of the cathode plate gas flow channel groove is 0.4mm.

[0109] The annealing temperature of this comparative example is too high, resulting in the precipitation of a brittle phase in the iron-based matrix, which leads to cracking of the matrix.

[0110] It can be seen from the above embodiments and comparative examples that the preparation process parameters of the embodiments are all within the required range of the present invention, and the obtained fuel cell cathode plate can effectively avoid the cathode poisoning problem caused by Cr volatilization at 600°C to 900°C.

[0111] One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

[0112] Low energy consumption and low pollution: Compared with the traditional coating method, the cold rolling composite technology adopted in the embodiment of the present invention does not require a high-temperature melting process, thereby significantly reducing energy consumption and pollutant emissions.

[0113] High production efficiency: Cold rolling composite technology can realize continuous production, greatly improve production efficiency and shorten production cycle.

[0114] Low cost: Since complex processes such as high-temperature melting and spraying are omitted, the production cost of the embodiment of the present invention is effectively controlled, making the product more competitive in the market.

[0115] Excellent performance: Through cold rolling composite and annealing treatment, a strong metallurgical bond is achieved between the iron-based matrix and the nickel-based matrix, ensuring the stability and durability of the Ni metal layer on the cathode side of the SOFC substrate.

[0116] Avoid poisoning of the battery cathode plate: The composite layer of Ni metal can effectively prevent the battery cathode plate from being poisoned due to contact with harmful substances, thereby extending the service life of SOFC.

[0117] The method provided by the embodiment of the present invention has the advantages of low energy consumption, low pollution, high production efficiency and low cost compared with the coating method.

[0118] The above is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. It will be apparent to those skilled in the art that various modifications to these embodiments are possible, and the general principles defined in the present application can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown in the present application, but will conform to the widest scope consistent with the principles and novel features applied for by the present application.

Claims

1. A method for preparing a cathode plate of a fuel cell that is resistant to cathode poisoning, the method comprising: Obtaining an iron-based substrate having a set chemical composition and a first set thickness; Obtaining a nickel-based substrate having a second set thickness; Grinding and degreasing the iron-based substrate and the nickel-based substrate, and controlling the surface roughness of the iron-based substrate and the nickel-based substrate; Cold composite rolling the degreased iron-based substrate and the nickel-based substrate to obtain a composite strip; The composite strip is sequentially subjected to annealing, trimming and sizing, and flow channel machining to obtain a cathode plate.

2. The method according to claim 1, characterized in that The deformation amount of a single pass of the cold composite rolling is 40% to 75%.

3. The method according to claim 1, characterized in that The annealing temperature is 270°C to 350°C, the annealing holding time is 1h to 5h, and the annealing hydrogen injection volume is ≥ 20m 3 / h.

4. The method according to claim 1, characterized in that: The surface roughness of the iron-based substrate is 80 μm to 120 μm; and / or, The surface roughness of the nickel-based substrate is 50 μm to 80 μm.

5. The method according to claim 1, characterized in that In terms of mass fraction, the set chemical composition includes: Cr: 20% to 25%, Nb: 0.2% to 1.0%, W: 1% to 3%, Si: 0.15% to 0.3%, Mn: 0.1% to 0.8%, Al: 0.15% to 0.4%, C+N≤0.010%, O≤0.0020%, and matrix element Fe; wherein C+N represents the sum of the mass fractions of C and N.

6. The method according to claim 1, characterized in that The first set thickness is 2 mm to 7 mm.

7. The method according to claim 1, characterized in that Measured by mass fraction, the chemical composition of the nickel-based substrate includes: Ni≥99.5%.

8. The method according to claim 1, characterized in that The second set thickness satisfies the following relationship: 0.1mm≥h*ka≥0.01mm; Wherein, h represents the second set thickness of the nickel-based substrate, k represents the deformation rate of the nickel-based substrate during the cold composite rolling process, and a represents the processing depth of the runner machining.

9. The method according to claim 1, characterized in that: In an O2-H2O atmosphere, after the cathode plate is oxidized at 600°C to 900°C for 40,000 hours, ASR is ≤ 0.015Ω·cm 2 .

10. The method according to claim 1, characterized in that The cathode plate is at a temperature above 900°C, when passing 400mA / cm 2 After 4000h of polarization with a current of 10000, the Cr-containing substances deposited at the cathode are ≤0.05mg / cm 2 .

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