A connector for flat tube solid oxide fuel cell and a preparation method thereof

Abstract

The invention discloses a connector for a flat tube solid oxide fuel cell and a preparation method thereof, belonging to the technical field of fuel cell materials. The preparation method comprises the following steps: (1) mixing ceramic material, nickel oxide, binder, plasticizer, polyethylene glycol, triethanolamine and anhydrous ethanol uniformly to obtain a spray slurry; (2) spraying the spray slurry obtained in step (1) on the surface of a substrate material and drying it, repeating the spraying and drying, and then sintering to obtain the connector. The invention can achieve controllable thickness of the connector by adjusting the slurry ratio and superimposing spraying and drying, and can achieve low-temperature sintering densification at 1350°C, which can greatly reduce losses and save costs in industrial production. The obtained connector has a dense surface without cracks, a tight interface, a uniform thickness, and no penetrating gas pores, and has the characteristics of high air tightness, high density, and high operating voltage.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cell materials, and in particular to a connector for a flat tube solid oxide fuel cell and a preparation method thereof. Background Art

[0002] Solid Oxide Fuel Cell (SOFC) is an energy conversion device that directly converts the chemical energy of fuel into electrical energy. It has the advantages of high energy conversion rate, strong fuel adaptability and environmental friendliness.

[0003] SOFC has very high requirements for the electrical conductivity, physical and chemical stability, and thermal expansion performance of the connection materials at high temperatures. After working for a long time in the high temperature environment of SOFC, traditional stainless steel materials have the risk of volatilization and diffusion of Cr elements and contamination of the oxygen electrode. Their own oxidation will also lead to an increase in resistivity, which is not conducive to the electrochemical performance of SOFC.

[0004] Therefore, researchers are committed to developing ceramic interconnect materials with good electrical conductivity. However, currently common ceramic interconnect materials require high temperatures above 1500°C to achieve material densification. In engineering applications, the increase in calcination temperature will generate a lot of energy consumption and increase costs. How to achieve low-temperature densification of ceramic interconnect materials is one of the problems that need to be solved urgently. At the same time, the thickness of the commonly used interconnect preparation methods is difficult to directly control, and the obtained interconnects also have problems such as poor density, low working voltage, and poor flatness. A solid oxide fuel cell interconnect with high flatness, tight and uniform bonding, high working voltage, controllable thickness and low-temperature dense sintering is urgently needed. Summary of the invention

[0005] In order to solve the above technical problems, the purpose of the present invention is to provide a connector for a flat tube solid oxide fuel cell and a preparation method thereof, so as to solve the problems of high calcination temperature, low flatness, density, operating voltage, and difficulty in direct thickness control during the preparation of existing SOFC connectors.

[0006] The technical solution of the present invention to solve the above technical problems is as follows:

[0007] A method for preparing a connector for a flat tube solid oxide fuel cell comprises the following steps:

[0008] (1) mixing ceramic material, nickel oxide, binder, plasticizer, polyethylene glycol, triethanolamine and anhydrous ethanol to obtain a spray slurry;

[0009] (2) spraying the spray slurry obtained in step (1) onto the surface of the base material and drying it, repeating the spraying and drying steps, and then sintering the slurry to obtain the product.

[0010] The beneficial effects of the present invention are as follows: the present invention uses ceramic material, nickel oxide, binder, plasticizer, polyethylene glycol, triethanolamine and anhydrous ethanol as raw materials to prepare spray slurry, and sprays the connector on the surface of the flat tube solid oxide fuel cell by spraying. By adjusting the ratio of the slurry and the spray drying superposition method, the thickness of the connector can be effectively controlled; at the same time, the connector for the flat tube solid oxide fuel cell prepared by the present invention can be densified at a lower temperature, and the connector structure can achieve co-contraction with the flat tube solid oxide fuel cell, with uniform thickness, dense structure, and no penetrating gas pores, thereby ensuring high airtightness, greatly reducing losses in industrial production, and saving costs.

[0011] Furthermore, in step (1), the mass volume ratio of the ceramic material, nickel oxide, binder, plasticizer, polyethylene glycol, triethanolamine and anhydrous ethanol is 8-12 g: 0.8-1.2 g: 0.3-0.7 g: 3-5 g: 0.8-1.2 mL: 0.5-1 mL: 50-200 mL.

[0012] Furthermore, the mass volume ratio of the ceramic material, nickel oxide, binder, plasticizer, polyethylene glycol, triethanolamine and anhydrous ethanol is 10g:1g:0.5g:4g:1mL:0.7mL:140mL.

[0013] The beneficial effect of adopting the above-mentioned further technical scheme is: the two organic components of polyethylene glycol and triethanolamine are added in the present invention, and through the interaction with the plasticizer therein, the plasticity, fluidity and adhesion of the prepared spray slurry are effectively improved, thereby effectively improving the self-strength of the prepared connector and the bonding strength and density between the connector and the substrate.

[0014] Furthermore, the ceramic material is La 1-x Sr x Ti 1-y Mn y O3, x=0.1~0.4, y=0.1~0.4, powder particle size is 200~500nm.

[0015] Preferably, the ceramic material is La 0.6 Sr 0.4 Ti 0.6 Mn 0.4 O3.

[0016] The beneficial effects of adopting the above further technical solution are: the present invention uses La 1-x Sr x Ti 1-y Mn yO3 is a ceramic material, which ensures high bonding performance between the connector and the base material, and effectively isolates the contact between the fuel gas and the air through its own high air tightness, thereby achieving high conductivity.

[0017] Furthermore, the binder is any one of polyvinyl butyral, polyvinyl alcohol and acrylic resin; and the plasticizer is dibutyl phthalate or dioctyl phthalate.

[0018] The beneficial effects of adopting the above-mentioned further technical scheme are as follows: the present invention uses phthalate substances as plasticizers, which not only improves the plasticity of the slurry, but also works together with polyethylene glycol and triethanolamine to improve the plasticity, fluidity and adhesion of the slurry; polyvinyl butyral is added as a binder, which interacts with other organic components in the raw materials, improves the strength of the connector layer after drying, and improves the bonding strength between the connector and the substrate.

[0019] Furthermore, in step (2), the substrate material is a flat tube solid oxide fuel cell.

[0020] Furthermore, in step (2), the drying temperature is 60-70° C. and the drying time is 1-5 min.

[0021] Preferably, the drying temperature is 70° C. and the drying time is 3 minutes.

[0022] The beneficial effect of adopting the above-mentioned further technical scheme is as follows: the present invention performs drying treatment at a relatively low temperature not exceeding 70°C, which not only ensures the drying effect and molding condition of the connector after spraying, but also effectively avoids the rapid volatilization of ethanol on the surface of the connector caused by high drying temperature, resulting in a large number of cracks, uneven surface, and affecting the density after high-temperature calcination.

[0023] Furthermore, the number of times of spraying and drying in step (2) is 5-10 times.

[0024] The beneficial effect of adopting the above further technical solution is that the present invention can achieve efficient and controllable thickness of the obtained connector by multiple spraying and drying methods through such a superposition method.

[0025] Furthermore, in step (2), the sintering temperature is 1300-1400° C. and the sintering time is 3-7 hours.

[0026] Preferably, the sintering temperature in step (2) is 1350° C. and the sintering time is 5 hours.

[0027] The beneficial effect of adopting the above further technical solution is that the present invention can achieve high densification of the connector through a relatively low calcination temperature of 1350° C., which can greatly reduce losses and save costs in industrial production.

[0028] A connector for a flat tube solid oxide fuel cell is prepared by the above-mentioned preparation method.

[0029] The present invention has the following beneficial effects:

[0030] The present invention provides a method for preparing a connector for a flat tube solid oxide fuel cell. The thickness of the connector can be controlled by adjusting the slurry ratio and spraying and drying. Low-temperature sintering and densification can be achieved at 1350°C, which can greatly reduce losses and save costs in industrial production. The connector for a flat tube solid oxide fuel cell prepared has a dense surface without cracks, a tight interface, a uniform thickness of the connector, and no penetrating gas channels. It has high air tightness and high density, can avoid gas leakage in actual work, and can reach a high working voltage of 1.09V under a 750°C discharge test. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a schematic diagram of the structure of a flat tube solid oxide fuel cell with a connector prepared in Example 1, wherein 1-connector, 2-anode support, 3-functional layer, 4-pore, 5-electrolyte;

[0032] Figure 2 The microscopic morphology of the connector for flat tube solid oxide fuel cell prepared in Example 1, wherein (a) is the surface, and (b) is the cross section;

[0033] Figure 3 The microscopic morphology of the connector for flat tube solid oxide fuel cell prepared in Example 2, wherein (a) is the surface, and (b) is the cross section;

[0034] Figure 4 This is a cross-sectional microscopic morphology of the connector for a flat tube solid oxide fuel cell prepared in Example 3;

[0035] Figure 5 The surface microscopic morphology of the connector for flat tube solid oxide fuel cell prepared in Example 1 and Comparative Example 2 are shown in FIG. 1 and FIG. 2, wherein (a) Comparative Example 1 and (b) Comparative Example 2;

[0036] Figure 6 This is a discharge power curve of the flat tube solid oxide fuel cell with a connector prepared in Example 1. DETAILED DESCRIPTION

[0037] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples are only used to explain the present invention and are not used to limit the scope of the present invention. If specific conditions are not specified in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0038] Embodiment 1:

[0039] A method for preparing a connector for a flat tube solid oxide fuel cell comprises the following steps:

[0040] (1) Using La with a particle size of 200 to 500 nm 0.6 Sr 0.4 Ti 0.6 Mn 0.4 O3 powder (LSTM) is used as the raw material. 1 g of nickel oxide, 0.5 g of polyvinyl butyral, 4 g of dibutyl phthalate, 1 mL of polyethylene glycol, 0.7 mL of triethanolamine and 140 mL of anhydrous ethanol are added to every 10 g of LSTM. The mixture is mixed by sand milling to obtain a spray slurry.

[0041] (2) The vertical distance of spraying is set to 10 cm, and the half-cell is used as the spraying base. The lateral movement distance of the nozzle along the half-cell is set to 3 cm for spraying; after spraying, the half-cell is placed in a constant temperature drying oven at 70°C for 3 minutes, and the above spraying and drying steps are repeated 5 times.

[0042] (3) The spray-dried half-cell is placed in a box-type muffle furnace and kept at 1350° C. for 5 hours to obtain a connector for a flat tube solid oxide fuel cell.

[0043] The schematic diagram of the obtained flat tube solid oxide fuel cell structure with a connector is as follows: Figure 1 shown.

[0044] Embodiment 2:

[0045] A method for preparing a connector for a flat tube solid oxide fuel cell comprises the following steps:

[0046] (1) Using La with a particle size of 200 to 500 nm 0.6 Sr 0.4 Ti 0.6 Mn 0.4 O3 powder (LSTM) is used as the raw material. 1 g of nickel oxide, 0.5 g of polyvinyl butyral, 4 g of dibutyl phthalate, 1 mL of polyethylene glycol, 0.7 mL of triethanolamine and 140 mL of anhydrous ethanol are added to every 10 g of LSTM. The mixture is mixed by sand milling to obtain a spray slurry.

[0047] (2) The vertical distance of spraying is set to 10 cm, the half-cell is used as the spraying base, and the lateral movement distance of the nozzle along the half-cell is set to 3 cm for spraying; after spraying, the half-cell is placed in a constant temperature drying oven at 70°C for 3 minutes, and the above spraying and drying steps are repeated 10 times.

[0048] (3) The spray-dried half-cell is placed in a box-type muffle furnace and kept at 1350° C. for 5 hours to obtain a connector for a flat tube solid oxide fuel cell.

[0049] Embodiment 3:

[0050] A method for preparing a connector for a flat tube solid oxide fuel cell comprises the following steps:

[0051] (1) Using La with a particle size of 200 to 500 nm 0.6 Sr 0.4 Ti 0.6 Mn 0.4 O3 powder (LSTM) is used as the raw material. 1 g of nickel oxide, 0.5 g of polyvinyl butyral, 4 g of dibutyl phthalate, 1 mL of polyethylene glycol, 0.7 mL of triethanolamine and 70 mL of anhydrous ethanol are added to every 10 g of LSTM. The mixture is mixed by sand milling to obtain a spray slurry.

[0052] (2) The vertical distance of spraying is set to 10 cm, the half-cell is used as the spraying base, and the lateral movement distance of the nozzle along the half-cell is set to 3 cm for spraying; after spraying, the half-cell is placed in a constant temperature drying oven at 70°C for 3 minutes, and the above spraying and drying steps are repeated 10 times.

[0053] (3) The spray-dried half-cell is placed in a box-type muffle furnace and kept at 1350° C. for 5 hours to obtain a connector for a flat tube solid oxide fuel cell.

[0054] Comparative Example 1:

[0055] A method for preparing a connector for a flat tube solid oxide fuel cell comprises the following steps:

[0056] (1) Using La with a particle size of 200 to 500 nm 0.6 Sr 0.4 Ti 0.6 Mn 0.4 O3 powder (LSTM) is used as the raw material. 1 g of nickel oxide, 0.5 g of polyvinyl butyral, 4 g of dibutyl phthalate, 1 mL of polyethylene glycol, 0.7 mL of triethanolamine and 140 mL of anhydrous ethanol are added to every 10 g of LSTM. The mixture is mixed by sand milling to obtain a spray slurry.

[0057] (2) The vertical distance of spraying is set to 10 cm, and the half-cell is used as the spraying base. The lateral movement distance of the nozzle along the half-cell is set to 3 cm for spraying; after spraying, the half-cell is placed in a constant temperature drying oven at 80°C for 3 minutes, and the above spraying and drying steps are repeated 5 times.

[0058] (3) The spray-dried half-cell is placed in a box-type muffle furnace and kept at 1350° C. for 5 hours to obtain a connector for a flat tube solid oxide fuel cell.

[0059] Comparative Example 2:

[0060] A method for preparing a connector for a flat tube solid oxide fuel cell comprises the following steps:

[0061] (1) Using La with a particle size of 200 to 500 nm 0.6 Sr 0.4 Ti 0.6 Mn 0.4 O3 powder (LSTM) is used as the raw material. 1 g of nickel oxide, 0.5 g of polyvinyl butyral, 4 g of dibutyl phthalate, 1 mL of polyethylene glycol, 0.7 mL of triethanolamine and 140 mL of anhydrous ethanol are added to every 10 g of LSTM. The mixture is mixed by sand milling to obtain a spray slurry.

[0062] (2) The vertical distance of spraying is set to 10 cm, the half-cell is used as the spraying base, and the lateral movement distance of the nozzle along the half-cell is set to 3 cm for spraying; after spraying, the half-cell is placed in a constant temperature drying oven at 100°C for 3 minutes, and the above spraying and drying steps are repeated 5 times.

[0063] (3) The spray-dried half-cell is placed in a box-type muffle furnace and kept at 1350° C. for 5 hours to obtain a connector for a flat tube solid oxide fuel cell.

[0064] Test Example 1: Performance Characterization

[0065] (1) The surface morphology and cross-sectional morphology of the interconnects for flat tube solid oxide fuel cells prepared in Examples 1-3 and Comparative Examples 1-2 were characterized using a scanning electron microscope.

[0066] The experimental results are as follows Figure 2-Figure 5 shown.

[0067] according to Figure 2-Figure 4It can be seen from the cross-sectional microscopic morphology that the thicknesses of the connectors for flat tube solid oxide fuel cells prepared in Examples 1 to 3 are 5.10 μm, 10.75 μm and 14.13 μm, respectively. The results show that the connectors for flat tube solid oxide fuel cells prepared in the present invention can achieve controllable thickness of the connectors by adjusting the slurry ratio and multiple spraying, drying and superposition. At the same time, the connectors for flat tube solid oxide fuel cells prepared in Examples 1-3 have uniform cross-sectional structure and thickness, and have no obvious pore structure, which ensures the compactness and high air tightness of the structure and can effectively avoid the problem of gas leakage in actual work. The half-cell of the flat tube solid oxide fuel cell has a shrinkage rate of 20% during sintering, but the connectors prepared in Examples 1-3 of the present invention are tightly fitted to achieve shrinkage, and high density can be achieved by calcining at only 1350°C, which can greatly reduce consumption and save costs in industrial production.

[0068] according to Figure 2 , Figure 3 and Figure 5 It can be seen from the surface microscopic morphology diagram in that the surface of the connector for flat tube solid oxide fuel cells prepared in Example 1 and Example 2 of the present invention is dense and crack-free, and the interface is tightly bonded; while after the drying temperature is increased in Comparative Example 1 and Comparative Example 2, the connector for flat tube solid oxide fuel cells prepared has gradually obvious cracks due to factors such as rapid volatilization of ethanol, and the surface is uneven. After high-temperature calcination, the density is seriously affected, which is not conducive to obtaining the electrical properties of the single cell.

[0069] (2) Discharge test

[0070] The single cell obtained after spraying the connector in Example 1 was subjected to a discharge test. One end of the single cell was inserted into the mold, sealed with glass powder and conductive glue, and silver paste was coated on both ends of the battery and connected with a silver mesh to collect current. The sealed single cell was placed in a high-temperature furnace, 50 mL / min of hydrogen was introduced into the air inlet as fuel gas, and the cathode side was placed in the air as oxidizing gas. The Arbin-MT2000 fuel cell test system was used to perform a discharge test at 750°C.

[0071] The experimental results are as follows Figure 6 shown.

[0072] According to the content in the figure, the 750°C test voltage of a single cell having a connector for a flat tube solid oxide fuel cell prepared in Example 1 of the present invention can reach 1.09V, indicating that the connector for a flat tube solid oxide fuel cell prepared in the present invention has a dense structure, ensuring that the battery does not leak.

[0073] 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, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a connector for a flat tube solid oxide fuel cell, characterized in that: The following steps are involved: (1) mixing ceramic material, nickel oxide, binder, plasticizer, polyethylene glycol, triethanolamine and anhydrous ethanol to obtain a spray slurry; (2) spraying the spray slurry obtained in step (1) onto the surface of the base material and drying it, repeating the spraying and drying, and then sintering the slurry to obtain; The ceramic material is La 1-x Sr x Ti 1-y Mn y O3, x=0.1~0.4, y=0.1~0.4, powder particle size is 200~500nm; The drying temperature in step (2) is 60-70° C. and the drying time is 1-5 min; The number of times of spraying and drying in the step (2) is 5-10 times.

2. The method for preparing a connector for a flat tube solid oxide fuel cell according to claim 1, characterized in that: In the step (1), the mass volume ratio of the ceramic material, nickel oxide, binder, plasticizer, polyethylene glycol, triethanolamine and anhydrous ethanol is 8-12 g: 0.8-1.2 g: 0.3-0.7 g: 3-5 g: 0.8-1.2 mL: 0.5-1 mL: 50-200 mL.

3. The method for preparing a connector for a flat tube solid oxide fuel cell according to claim 2, characterized in that: The mass volume ratio of ceramic material, nickel oxide, binder, plasticizer, polyethylene glycol, triethanolamine and anhydrous ethanol is 10g:1g:0.5g:4g:1mL:0.7mL:140mL.

4. The method for preparing a connector for a flat tube solid oxide fuel cell according to any one of claims 1 to 3, characterized in that: The binder is any one of polyvinyl butyral, polyvinyl alcohol and acrylic resin; the plasticizer is dibutyl phthalate or dioctyl phthalate.

5. The method for preparing a connector for a flat tube solid oxide fuel cell according to claim 1, characterized in that: In the step (2), the substrate material is a flat tube solid oxide fuel cell.

6. The method for preparing a connector for a flat tube solid oxide fuel cell according to claim 1, characterized in that: The sintering temperature in step (2) is 1300-1400° C. and the sintering time is 3-7 hours.

7. A connector for a flat tube solid oxide fuel cell, characterized in that: The method is prepared according to any one of claims 1 to 6.

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