A tubular SOFC and a method for manufacturing the same

Abstract

The application provides a tubular SOFC and a preparation method thereof. The preparation method comprises the following steps: preparing an electrolyte green body layer and an anode green body layer by rotating centrifugation, respectively controlling electrolyte slurry composition and centrifugation process parameters in the preparation of the electrolyte green body layer, respectively controlling anode slurry composition and centrifugation process parameters in the preparation of the anode green body layer, then preparing a half cell by co-firing, and finally preparing a cathode layer, so as to obtain the tubular SOFC. The preparation method can solve the problems of complex preparation process and uneven multilayer ceramic caused by special equipment, and improve the electrochemical performance of the material.

Description

Technical Field

[0001] This invention relates to the field of batteries, and in particular to a tubular SOFC and its preparation method. Background Technology

[0002] Solid oxide fuel cells (SOFCs) are all-solid-state power generation devices that efficiently and environmentally convert the chemical energy of fuel and oxidant into electrical energy. They mainly consist of a cathode, anode, and electrolyte, and can be broadly classified into planar and tubular types based on their support structure. Compared to planar SOFCs, tubular SOFCs are favored by research institutions and industry due to their advantages such as not requiring high-temperature sealing (sealing can be done at the cold end) and stable performance. The highly symmetrical structure of tubular SOFCs makes them less prone to cracking due to stress between functional layers during heating and cooling, resulting in better thermal cycling stability. This effectively shortens the start-up time of tubular SOFCs, making them more suitable for applications requiring rapid start-up and shutdown, such as mobile power equipment.

[0003] However, the fabrication of tubular SOFCs typically requires specialized equipment such as extruders and isostatic presses, making the process difficult and costly. Furthermore, the preforms prepared by extruders and isostatic presses often suffer from poor symmetry and uneven electrolyte layers, affecting battery performance.

[0004] The invention patent "A method for preparing an anode-supported SOFC electrolyte film (CN113270591B)" relates to a method for preparing an anode-supported SOFC electrolyte film. This patent only uses centrifugal deposition forming technology to prepare the electrolyte film, while the anode is prepared on the electrolyte layer by cold isostatic pressing technology. It is difficult to ensure that the center of the electrolyte and the center of the anode are aligned, so its symmetry is poor.

[0005] The invention patent "Centrifugal Preparation Method of Electrolyte Film for Solid Oxide Fuel Cells (CN105047973A)" relates to a centrifugal preparation method for electrolyte films in solid oxide fuel cells. The patent reports that the anode is prepared by dry pressing, and the electrolyte film is prepared by centrifugation. However, this method requires the anode preform to be calcined at high temperature before centrifugation to prepare the electrolyte layer, resulting in a cumbersome and complex process and suboptimal product performance. Summary of the Invention

[0006] In view of this, the present invention provides a tubular SOFC and its preparation method. The preparation method provided by the present invention can improve the uniformity of multilayer ceramics and simplify the process, while ensuring the electrochemical performance of the product.

[0007] This invention provides a method for preparing a tubular SOFC, comprising the following steps:

[0008] A) Centrifugal deposition to prepare electrolyte green layer:

[0009] The electrolyte slurry is added into a tubular mold, and then the tubular mold is placed on a centrifuge for high-speed centrifugation. After centrifugation, the residual liquid is poured out and then dried to form an electrolyte green layer.

[0010] The above steps are repeated n times for centrifugal deposition until the desired thickness of the electrolyte green layer is obtained;

[0011] in:

[0012] n≥1;

[0013] The high-speed centrifugation speed is 300-3000 rpm, and the time is 2-60 min;

[0014] The electrolyte slurry comprises the following components in the following mass ratio:

[0015] Zirconia-based electrolyte: 0.01%–50%;

[0016] Adhesive 0%–10%;

[0017] Solvent 40%–99.9%;

[0018] B) Centrifugal deposition for preparing the anodic green layer:

[0019] The anode slurry is added into the tubular mold with the electrolyte green layer obtained in step A), and then the tubular mold is placed on a centrifuge for high-speed centrifugation. After centrifugation, the residual liquid is poured out and then dried to form an anode green layer on the surface of the electrolyte green layer.

[0020] The above steps are followed for a total of m centrifugal depositions until the required thickness of the anodic green sheet is obtained;

[0021] in:

[0022] m≥1;

[0023] The high-speed centrifugation speed is 300-3000 rpm, and the time is 2-60 min;

[0024] The anode slurry comprises the following components in the following mass ratio:

[0025]

[0026] C) Co-firing:

[0027] The tubular mold with electrolyte green layer and anode green layer obtained in step B) is placed in the furnace for calcination, and then demolded to obtain a tubular half cell with electrolyte layer and anode support layer.

[0028] Wherein, the calcination is gradient calcination;

[0029] The gradient calcination process is as follows:

[0030] First step: Raise the temperature from room temperature to the first temperature, and then hold it at that temperature; the first temperature is 200-800℃, and the holding time is 0.1-30h.

[0031] The second step involves raising the temperature from the first temperature to the second temperature and then holding it at that temperature; the second temperature is between 600 and 1200°C, and the holding time is between 0.1 and 30 hours.

[0032] The third step: the temperature is increased from the second temperature to the third temperature, and then held at that temperature; the third temperature is 1200-1600℃, and the holding time is 0.1-30h.

[0033] In the gradient calcination, the first temperature < the second temperature < the third temperature;

[0034] D) Preparation of cathode:

[0035] A cathode layer is prepared on the surface of the electrolytic layer of the tubular half-cell obtained in step C) to obtain a tubular SOFC.

[0036] Preferably, in the electrolyte slurry:

[0037] The zirconium oxide-based electrolyte is YSZ and / or ScYSZ;

[0038] The adhesive is at least one of polyvinyl alcohol, polyvinyl butyral, ethyl cellulose and acrylic emulsion;

[0039] The solvent is at least one selected from water, ethanol, xylene, n-butanol, and isopropanol.

[0040] Preferably, in the anode slurry:

[0041] The zirconium oxide-based electrolyte is YSZ and / or ScYSZ;

[0042] The pore-forming agent is at least one of graphite, starch, and polymethyl methacrylate;

[0043] The adhesive is at least one of polyvinyl alcohol, polyvinyl butyral, ethyl cellulose and acrylic emulsion;

[0044] The solvent is at least one selected from water, ethanol, xylene, n-butanol, and isopropanol.

[0045] Preferably, in step C):

[0046] In the first step, the heating rate is 0.1–5 °C / min;

[0047] In the second step, the heating rate is 0.1–5 °C / min;

[0048] In the third step, the heating rate is 0.1–5 °C / min.

[0049] Preferably, in step C), after calcination, the temperature is further reduced before demolding.

[0050] Preferably, in step D), the cathode active material in the cathode layer is La. 1-x Sr x Co 1-y Fe y O3, where 0≤x≤1, 0≤y≤1.

[0051] Preferably, in step D), the method for preparing the cathode layer specifically includes: coating the cathode slurry onto the surface of the electrolyte layer of the half-cell obtained in step C), and then calcining it to form the cathode layer;

[0052] The cathode slurry comprises the following components in the indicated mass ratios:

[0053]

[0054] The cathode powder is La. 1-x Sr x Co 1-y Fe y O3, where 0≤x≤1, 0≤y≤1.

[0055] Preferably, in the cathode slurry:

[0056] The pore-forming agent is at least one of graphite, starch, and polymethyl methacrylate;

[0057] The dispersant is at least one of terpineol, fish oil and triethanolamine;

[0058] The adhesive is at least one of polyvinyl alcohol, polyvinyl butyral, ethyl cellulose, and acrylic emulsion.

[0059] Preferably, the calcination temperature in step D) is 500–1300°C, and the holding time is 0–30 h.

[0060] The present invention also provides a tubular SOFC prepared by the preparation method described in the above technical solution.

[0061] The present invention provides a method for preparing a tubular SOFC (solid oxide fuel cell), which involves preparing an electrolyte green layer and an anode green layer separately by rotational centrifugation. The electrolyte slurry composition and centrifugation process parameters are controlled during the preparation of the electrolyte green layer, and the anode slurry composition and centrifugation process parameters are also controlled during the preparation of the anode green layer. Then, a half-cell is prepared in one step by co-firing, and finally, a cathode layer is prepared to obtain the tubular SOFC. This method overcomes the drawbacks of complex preparation processes and inhomogeneous multilayer ceramics caused by specialized equipment, and improves the electrochemical performance of the material.

[0062] Experimental results show that the tubular SOFC provided by this invention has a maximum output power of 363 mW / cm². -2 It exhibits excellent output characteristics; its ohmic impedance is 0.35Ωcm. 2 The polarization impedance is 0.42 Ωcm. 2 It exhibits excellent impedance characteristics. Attached Figure Description

[0063] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0064] Figure 1 This is a schematic diagram of a tubular mold being fixed on a centrifuge.

[0065] Figure 2 This is a schematic diagram of the structure of the tubular half-cell before demolding in step C) of the preparation method of the present invention;

[0066] Figure 3 This is a discharge curve of the battery in Example 1 at 650°C using hydrogen as fuel;

[0067] Figure 4 The AC impedance spectrum of the battery in Example 1 at 650°C under open-circuit voltage conditions;

[0068] Figure 5 Here is a SEM image of the cross-section of the battery in Example 1; where, Figure 5 (a) and 5(b) are SEM images at different magnifications. Detailed Implementation

[0069] This invention provides a method for preparing a tubular SOFC, comprising the following steps:

[0070] A) Centrifugal deposition to prepare electrolyte green layer:

[0071] The electrolyte slurry is added into a tubular mold, and then the tubular mold is placed on a centrifuge for high-speed centrifugation. After centrifugation, the residual liquid is poured out and then dried to form an electrolyte green layer.

[0072] The above steps are repeated n times for centrifugal deposition until the desired thickness of the electrolyte green layer is obtained;

[0073] in:

[0074] n≥1;

[0075] The high-speed centrifugation speed is 300-3000 rpm, and the time is 2-60 min;

[0076] The electrolyte slurry comprises the following components in the following mass ratio:

[0077] Zirconia-based electrolyte: 0.01%–50%;

[0078] Adhesive 0%–10%;

[0079] Solvent 40%–99.9%;

[0080] B) Centrifugal deposition for preparing the anodic green layer:

[0081] The anode slurry is added into the tubular mold with the electrolyte green layer obtained in step A), and then the tubular mold is placed on a centrifuge for high-speed centrifugation. After centrifugation, the residual liquid is poured out and then dried to form an anode green layer on the surface of the electrolyte green layer.

[0082] The above steps are followed for a total of m centrifugal depositions until the required thickness of the anodic green sheet is obtained;

[0083] in:

[0084] m≥1;

[0085] The high-speed centrifugation speed is 300-3000 rpm, and the time is 2-60 min;

[0086] The anode slurry comprises the following components in the following mass ratio:

[0087]

[0088]

[0089] C) Co-firing:

[0090] The tubular mold with electrolyte green layer and anode green layer obtained in step B) is placed in the furnace for calcination, and then demolded to obtain a tubular half cell with electrolyte layer and anode support layer.

[0091] Wherein, the calcination is gradient calcination;

[0092] The gradient calcination process is as follows:

[0093] First step: Raise the temperature from room temperature to the first temperature, and then hold it at that temperature; the first temperature is 200-800℃, and the holding time is 0.1-30h.

[0094] The second step involves raising the temperature from the first temperature to the second temperature and then holding it at that temperature; the second temperature is between 600 and 1200°C, and the holding time is between 0.1 and 30 hours.

[0095] The third step: the temperature is increased from the second temperature to the third temperature, and then held at that temperature; the third temperature is 1200-1600℃, and the holding time is 0.1-30h.

[0096] In the gradient calcination, the first temperature < the second temperature < the third temperature;

[0097] D) Preparation of cathode:

[0098] A cathode layer is prepared on the surface of the electrolytic layer of the tubular half-cell obtained in step C) to obtain a tubular SOFC.

[0099] Regarding step A) Centrifugal deposition to prepare the electrolyte green layer :

[0100] According to the present invention, electrolyte slurry is added into a tubular mold, and then the tubular mold is placed on a centrifuge for high-speed centrifugation. After centrifugation, the residual liquid is poured out and then dried to form an electrolyte green layer. The above steps are repeated n times for centrifugation deposition until an electrolyte green layer of the required thickness is obtained.

[0101] In this invention, the electrolyte slurry comprises the following components in the following mass ratio:

[0102] Zirconia-based electrolyte: 0.01%–50%;

[0103] Adhesive 0%–10%;

[0104] Solvent content: 40%–99.9%.

[0105] in:

[0106] The zirconia-based electrolyte is preferably YSZ (yttrium oxide-stabilized zirconia) and / or ScYSZ (scandium oxide-yttrium oxide-stabilized zirconia). The zirconia-based electrolyte constitutes 0.01% to 50% by mass in the electrolyte slurry, specifically 1.96%, 2.43%, 3.22%, 4.76%, 9.07%, 11.09%, 14.25%, 19.92%, 33.11%, and 49.50%.

[0107] The binder is preferably at least one selected from polyvinyl alcohol, polyvinyl butyral, ethyl cellulose, and acrylic emulsion. The binder constitutes 0% to 10% of the electrolyte slurry by mass, preferably excluding the endpoint 0%, and may specifically be 0.04%, 0.05%, 0.06%, 0.10%, 0.14%, 0.18%, 0.22%, 0.27%, 0.28%, 0.40%, 0.66%, 0.99%, or 1.10%.

[0108] The solvent is preferably at least one selected from water, ethanol, xylene, n-butanol, and isopropanol. The binder in the electrolyte slurry has a mass percentage of 40% to 90%, specifically 98.00%, 97.51%, 96.71%, 95.15%, 95.1%, 90.74%, 90.66%, 88.69%, 84.47%, 79.68%, 66.23%, 49.50%, and 43.96%, preferably a balance (i.e., to make up to 100%).

[0109] The present invention does not impose any special restrictions on the preparation method of the electrolyte slurry. The above components can be mixed evenly according to conventional methods in the art; for example, the above materials can be mixed evenly by ball milling to obtain the electrolyte slurry.

[0110] In this invention, the tubular mold is preferably a corundum tube or a quartz tube.

[0111] In this invention, when adding electrolyte slurry into a tubular mold, the amount of electrolyte slurry to be added is determined according to the length and contents of the tubular mold. Then, it is placed on a centrifuge for high-speed centrifugation. The sedimentation rate of electrolyte particles is controlled by controlling the composition of the slurry, the centrifugation speed and time, etc., thereby controlling the thickness of the electrolyte layer.

[0112] In this invention, the centrifuge is preferably a horizontal centrifuge. The tubular mold is placed and fixed on the centrifuge, and then high-speed centrifugation is performed. A schematic diagram of the tubular mold being fixed on the centrifuge is shown below. Figure 1 As shown, 1 is the motor connecting shaft, 2 is the tube fixing and limiting device, and 3 is the tubular mold.

[0113] In this invention, the rotation speed of the high-speed centrifuge is 300-3000 rpm, specifically 300 rpm, 400 rpm, 500 rpm, 600 rpm, 700 rpm, 800 rpm, 900 rpm, 1000 rpm, 1100 rpm, 1200 rpm, 1300 rpm, 1400 rpm, 1500 rpm, 1600 rpm, 1700 rpm, 1800 rpm, 1900 rpm, 2000 rpm, 2100 rpm, 2200 rpm, 2300 rpm, 2400 rpm, 2500 rpm, 2600 rpm, 2700 rpm, 2800 rpm, 2900 rpm, and 3000 rpm. The high-speed centrifugation time is 2 to 60 minutes, specifically 2 minutes, 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, and 60 minutes.

[0114] In this invention, after centrifugation, the residual liquid is poured off and then dried. The drying temperature is preferably 30–120°C, but can be carried out at room temperature. After drying, an electrolyte green layer is formed.

[0115] In this invention, the above steps are followed for a total of n centrifugal depositions until an electrolyte green layer of the desired thickness is obtained. Wherein, n ≥ 1. In each of the n centrifugal depositions, the subsequent centrifugal deposition is performed based on the electrolyte green layer obtained in the previous centrifugal deposition. For example, assuming a second centrifugal deposition is to be performed, after the electrolyte green layer is formed in the first centrifugal deposition, electrolyte slurry is added to a tubular mold containing the electrolyte green layer, and then the mold is centrifuged at high speed. After centrifugation, the residual liquid is poured out, and the mold is dried to form another electrolyte green layer. This process is repeated, with each resulting electrolyte green layer stacked on top of the others until the target thickness is reached. In this invention, there is no special limitation on the target thickness of the electrolyte layer; a conventional electrolyte layer thickness in the art is sufficient, generally 1–20 μm. In this invention, in each of the n centrifugal depositions, the high-speed centrifugation conditions (speed and time) are independently selected from the parameter range described above. That is, the high-speed centrifugation conditions in each centrifugal deposition are selected from the parameter range described above, but the centrifugation parameters in each centrifugal deposition can be the same or different.

[0116] Regarding step B) centrifugal deposition for preparing the anolyte green layer :

[0117] According to the present invention, the anode slurry is added into the tubular mold with the electrolyte green layer obtained in step A), and then the tubular mold is placed on a centrifuge for high-speed centrifugation. After centrifugation, the residual liquid is poured out and then dried to form an anode green layer on the surface of the electrolyte green layer. The above steps are performed for a total of m centrifugation depositions until the anode green layer of the required thickness is obtained.

[0118] In this invention, the anode slurry comprises the following components in the following mass ratio:

[0119]

[0120] in:

[0121] The mass percentage of NiO in the anode slurry is 0.4% to 45%, specifically 0.40%, 0.48%, 0.64%, 0.94%, 1.77%, 2.15%, 2.74%, 3.76%, 6.02%, 8.62%, 9.43%, 10.92%, 13.17%, 15.04%, 24.09%, 24.81%, 34.48%, and 37.73%.

[0122] The zirconia-based electrolyte is preferably YSZ (yttrium-stabilized zirconia) and / or ScYSZ (scandium-yttrium-stabilized zirconia). The zirconia-based electrolyte constitutes 0.4% to 45% by mass in the anode slurry, specifically 1.55%, 1.94%, 2.55%, 3.29%, 3.75%, 7.07%, 8.58%, 10.93%, 15.04%, 16.54%, 24.10%, 34.48%, and 37.74%.

[0123] The pore-forming agent is preferably at least one selected from graphite, starch, and polymethyl methacrylate (PMMA). The pore-forming agent constitutes 0% to 25% by mass in the anode slurry, specifically 0%, 0.16%, 0.48%, 0.73%, 0.96%, 1.41%, 2.65%, 3.22%, 4.10%, 5.64%, 8.27%, 9.04%, 12.93%, and 14.15%.

[0124] The binder is preferably at least one selected from polyvinyl alcohol, polyvinyl butyral, ethyl cellulose, and acrylic emulsion. The binder constitutes 0% to 1% by mass of the anode slurry, preferably excluding the endpoint 0%, and may specifically be 0.04%, 0.05%, 0.06%, 0.10%, 0.18%, 0.22%, 0.25%, 0.28%, 0.40%, 0.66%, 0.74%, or 0.99%.

[0125] The solvent is preferably at least one selected from water, ethanol, xylene, n-butanol, and isopropanol. The binder in the anode slurry has a mass percentage of 30% to 99.9%, specifically 98.00%, 97.51%, 96.71%, 95.15%, 90.74%, 88.69%, 84.47%, 83.13%, 79.68%, 66.23%, 49.63%, 49.50%, and 43.96%, preferably a balance (i.e., to make up to 100%).

[0126] The present invention does not impose any special restrictions on the preparation method of the anode slurry. The above components can be mixed evenly according to conventional methods in the art; for example, the above materials can be mixed evenly by ball milling to obtain the anode slurry.

[0127] In this invention, when the anode slurry is added to the tubular mold with the electrolyte green layer obtained in step A), the amount of anode slurry to be added is determined according to the length and contents of the tubular mold. Then, it is placed on a centrifuge for high-speed centrifugation. The settling speed of the anode particles is controlled by controlling the slurry composition, centrifugation speed and time, thereby controlling the thickness of the anode layer.

[0128] In this invention, the centrifuge is preferably a horizontal centrifuge. A tubular mold is placed and fixed on the centrifuge, and then high-speed centrifugation is performed. In this invention, the high-speed centrifugation speed is 300–3000 rpm, specifically 300 rpm, 400 rpm, 500 rpm, 600 rpm, 700 rpm, 800 rpm, 900 rpm, 1000 rpm, 1100 rpm, 1200 rpm, 1300 rpm, 1400 rpm, 1500 rpm, 1600 rpm, 1700 rpm, 1800 rpm, 1900 rpm, 2000 rpm, 2100 rpm, 2200 rpm, 2300 rpm, 2400 rpm, 2500 rpm, 2600 rpm, 2700 rpm, 2800 rpm, 2900 rpm, and 3000 rpm. The high-speed centrifugation time is 2 to 60 minutes, specifically 2 minutes, 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, and 60 minutes.

[0129] In this invention, after centrifugation, the residual liquid is poured off, and then dried. The drying temperature is preferably 30–120°C, but can be carried out at room temperature. After drying, an anodic green layer is formed.

[0130] In this invention, a total of m centrifugal depositions are performed according to the above steps until the desired thickness and different porosity hierarchical structures of the anode green layer are obtained. Where m ≥ 1. In each of the m centrifugal depositions, the subsequent centrifugal deposition is performed based on the anode green layer obtained in the previous centrifugal deposition. For example, assuming a second centrifugal deposition is to be performed, after the anode green layer is formed in the first centrifugal deposition, anode slurry is added to a tubular mold containing the anode green layer, and then the mold is centrifuged at high speed. After centrifugation, the residual liquid is poured out, and the mold is dried to form another anode green layer. This process is repeated, with each anode green layer being superimposed on the others until the target thickness is reached. In this invention, there is no special limitation on the target thickness of the anode layer; a conventional anode thickness in the art is sufficient, generally 10–2000 μm. In this invention, in each of the m centrifugal depositions, the high-speed centrifugation conditions (speed and time) are independently selected from the parameter range described above. That is, the high-speed centrifugation conditions in each centrifugal deposition are selected from the parameter range described above, but the centrifugation parameters in each centrifugal deposition can be the same or different.

[0131] Regarding step C) co-firing :

[0132] According to the present invention, the tubular mold with electrolyte green layer and anode green layer obtained in step B) is placed in a furnace for calcination, and then demolded to obtain a tubular half cell with electrolyte layer and anode support layer.

[0133] In this invention, the furnace used for calcination is preferably a tube furnace.

[0134] In this invention, the calcination is a gradient calcination. The gradient calcination process is as follows:

[0135] The first step involves heating from room temperature to a first temperature, followed by holding at that temperature. The preferred heating rate is 0.1–5℃ / min, specifically 0.1℃ / min, 0.5℃ / min, 1℃ / min, 2℃ / min, 3℃ / min, 4℃ / min, or 5℃ / min. The first temperature is 200–800℃, specifically 200℃, 300℃, 400℃, 500℃, 600℃, 700℃, or 800℃. The holding time is 0.1–30 hours, specifically 0.5 hours, 1 hour, 4 hours, 6 hours, 10 hours, 15 hours, 20 hours, 25 hours, or 30 hours.

[0136] The second step involves heating from the first temperature to the second temperature, followed by holding at that temperature. The preferred heating rate is 0.1–5℃ / min, specifically 0.1℃ / min, 0.5℃ / min, 1℃ / min, 2℃ / min, 3℃ / min, 4℃ / min, or 5℃ / min. The second temperature is 600–1200℃, specifically 600℃, 700℃, 800℃, 900℃, 1000℃, 1100℃, or 1200℃. The holding time is 0.1–30 hours, specifically 0.5 hours, 1 hour, 4 hours, 8 hours, 10 hours, 15 hours, 20 hours, 25 hours, or 30 hours.

[0137] The third step involves raising the temperature from the second temperature to the third temperature, followed by holding at that temperature. The preferred heating rate is 0.1–5℃ / min, specifically 0.1℃ / min, 0.5℃ / min, 1℃ / min, 2℃ / min, 3℃ / min, 4℃ / min, or 5℃ / min. The third temperature is 1200–1600℃, specifically 1200℃, 1300℃, 1400℃, 1500℃, or 1600℃. The holding time is 0.1–30 hours, specifically 0.5 hours, 1 hour, 5 hours, 7 hours, 10 hours, 15 hours, 20 hours, 25 hours, or 30 hours.

[0138] In the gradient calcination process described above, the first temperature < the second temperature < the third temperature.

[0139] In this invention, after the above-mentioned calcination, a cooling process is also performed. Specifically, the cooling process involves reducing the temperature from a third temperature to room temperature; in practice, this is done during furnace cooling. The preferred cooling rate is 0.1–10 °C / min, specifically 0.1 °C / min, 0.5 °C / min, 1 °C / min, 2 °C / min, 3 °C / min, 4 °C / min, 5 °C / min, 6 °C / min, 7 °C / min, 8 °C / min, 9 °C / min, or 10 °C / min.

[0140] In this invention, after the aforementioned cooling process, the cell is demolded to obtain a tubular half-cell with an electrolyte layer and an anode support layer. Specifically, it is a porous tubular half-cell with a dense electrolyte layer on its surface. The structure of the tubular half-cell before demolding is as follows: Figure 2 As shown, 3 is a tubular mold, 4 is an electrolyte layer, and 5 is an anode support layer.

[0141] Regarding step D) preparing the cathode :

[0142] According to the present invention, a cathode layer is prepared on the surface of the electrolytic layer of the tubular half-cell obtained in step C) to obtain a tubular SOFC.

[0143] In this invention, the cathode active material in the cathode layer is preferably La. 1-x Srx Co 1-y Fe y O3, wherein 0 ≤ x ≤ 1, specifically 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0. 0 ≤ y ≤ 1, specifically 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0. This invention does not impose any special restrictions on the source of the cathode active material, which can be a commercially available product or prepared according to conventional methods in the art.

[0144] In this invention, the method for preparing the cathode layer preferably includes: coating the cathode slurry onto the surface of the electrolyte layer of the half-cell obtained in step C), and then calcining it to form the cathode layer.

[0145] In this invention, the cathode slurry preferably comprises the following components in the following mass ratio:

[0146]

[0147] in:

[0148] The cathode powder is La. 1-x Sr x Co 1-y Fe y O3, where 0 ≤ x ≤ 1, specifically 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0. 0 ≤ y ≤ 1, specifically 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0. In some embodiments of the present invention, the cathode powder is La. 0.6 Sr 0.4 Co 0.2 Fe 0.8 O3, La 0.4 Sr 0.6 Co 0.8 Fe 0.2 O3. The cathode powder in the cathode slurry has a mass percentage of 15% to 50%, specifically 15.30%, 20.86%, 25.22%, 26.08%, 26.99%, 27.97%, 29.03%, 30.17%, 31.40%, 32.73%, 34.19%, 35.78%, 37.52%, 39.45%, 41.58%, 43.96%, 45.87%, 46.62%, and 49.63%.

[0149] The pore-forming agent is preferably at least one selected from graphite, starch, and polymethyl methacrylate (PMMA). The pore-forming agent constitutes 0% to 20% by mass in the cathode paste, specifically 0.00%, 1.56%, 2.98%, 3.14%, 4.28%, 4.59%, 5.46%, 6.56%, 7.82%, 8.10%, 8.71%, 9.42%, 10.26%, 11.26%, 12.47%, 13.99%, 14.89%, 16.72%, 18.64%, and 19.83%.

[0150] The dispersant is preferably at least one selected from terpineol, fish oil, and triethanolamine. The dispersant constitutes 30% to 80% by mass in the cathode slurry, specifically 31.45%, 32.26%, 36.36%, 40.00%, 43.24%, 44.71%, 45.87%, 48.78%, 51.16%, 53.33%, 55.32%, 57.14%, 58.82%, 60.38%, 63.16%, 65.57%, 68.42%, 69.98%, 72.34%, 75.42%, 76.78%, and 79.63%.

[0151] The binder is preferably at least one selected from polyvinyl alcohol, polyvinyl butyral, ethyl cellulose, and acrylic emulsion. The binder constitutes 1.5% to 4% by mass of the cathode slurry, specifically 1.64%, 1.82%, 2.04%, 2.33%, 2.52%, 2.86%, 3.03%, 3.23%, 3.67%, 3.82%, and 3.99%.

[0152] The present invention does not impose any special restrictions on the preparation method of the cathode slurry. The above components can be mixed evenly according to conventional methods in the art; for example, the above materials can be mixed evenly by grinding and mixing to obtain the cathode slurry.

[0153] In this invention, the cathode paste is coated onto the surface of the electrolyte layer and then calcined. The preferred heating rate for calcination is 0.01–20 °C / min, specifically 0.5 °C / min, 1 °C / min, 2 °C / min, 3 °C / min, 4 °C / min, 5 °C / min, 6 °C / min, 7 °C / min, 8 °C / min, 9 °C / min, 10 °C / min, 11 °C / min, 12 °C / min, 13 °C / min, 14 °C / min, 15 °C / min, 16 °C / min, 17 °C / min, 18 °C / min, 19 °C / min, or 20 °C / min. The preferred target temperature for calcination is 500–1300 °C, specifically 500 °C, 600 °C, 700 °C, 800 °C, 900 °C, 1000 °C, 1100 °C, 1200 °C, or 1300 °C. The preferred holding time for calcination is 0 to 30 hours, specifically 0 hours, 2 hours, 4 hours, 6 hours, 8 hours, 10 hours, 12 hours, 14 hours, 16 hours, 18 hours, 20 hours, 22 hours, 24 hours, 26 hours, 28 hours, and 30 hours.

[0154] In this invention, after the above-mentioned calcination, a cooling process is also performed. In this invention, the cooling is to room temperature, and in actual operation, it is cooled along with the furnace. The preferred cooling rate is 0.01–20 °C / min, specifically 0.5 °C / min, 1 °C / min, 2 °C / min, 3 °C / min, 4 °C / min, 5 °C / min, 6 °C / min, 7 °C / min, 8 °C / min, 9 °C / min, 10 °C / min, 11 °C / min, 12 °C / min, 13 °C / min, 14 °C / min, 15 °C / min, 16 °C / min, 17 °C / min, 18 °C / min, 19 °C / min, and 20 °C / min. After the above treatment, a cathode layer is formed on the surface of the electrolyte layer, thereby obtaining a tubular SOFC.

[0155] The present invention also provides a tubular SOFC prepared by the preparation method described in the above technical solution. The obtained tubular SOFC includes an anode support layer, an electrolyte layer, and a cathode layer that are sequentially stacked and in contact.

[0156] The preparation method provided by this invention involves preparing an electrolyte green layer and an anode green layer separately by rotary centrifugation. The electrolyte slurry composition and centrifugation process parameters are controlled during the preparation of the electrolyte green layer, and the anode slurry composition and centrifugation process parameters are also controlled during the preparation of the anode green layer. Then, a half-cell is fabricated in one step through co-firing, and finally, a cathode layer is prepared to obtain a tubular SOFC. This preparation method overcomes the drawbacks of complex preparation processes and inhomogeneous multilayer ceramics caused by specialized equipment, and improves the electrochemical performance of the material.

[0157] Experimental results show that the tubular SOFC provided by this invention has a maximum output power of 363 mW / cm². -2 It exhibits excellent output characteristics; its ohmic impedance is 0.35Ωcm. 2 The polarization impedance is 0.42 Ωcm. 2 It exhibits excellent impedance characteristics.

[0158] To further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and are not intended to limit the scope of the claims of the present invention.

[0159] Example 1

[0160] A) Centrifugal deposition to prepare electrolyte green layer:

[0161] a1. Preparation of electrolyte slurry

[0162] Raw material composition:

[0163] Zirconia-based electrolyte YSZ 9.07%;

[0164] Polyvinyl butyral adhesive 0.27%;

[0165] Xylene solvent content: 90.66%.

[0166] Preparation: The above raw materials are ball-milled and mixed to obtain an electrolyte slurry.

[0167] a2. Pour the electrolyte slurry into a corundum tubular mold, then place the tubular mold on a horizontal centrifuge and fix it for high-speed centrifugation at 2000 rpm for 5 minutes. Then, pour out the residual liquid and dry it at room temperature to form an electrolyte green layer.

[0168] B) Centrifugal deposition for preparing the anodic green layer:

[0169] b1. Preparation of anode slurry

[0170] Raw material composition:

[0171]

[0172] Preparation: The above raw materials are ball-milled and mixed to obtain an anode slurry.

[0173] b2. Pour the anode slurry into the tubular mold with the electrolyte green layer obtained in step A), then fix the tubular mold on a horizontal centrifuge and centrifuge at high speed of 2000 rpm for 5 minutes. Then, pour out the residual liquid and dry it at room temperature to form the anode green layer.

[0174] C) Co-firing:

[0175] The tubular mold with electrolyte green sheet and anode green sheet obtained in step B) is placed in a furnace for gradient calcination. The gradient calcination process is as follows:

[0176] First step: Increase the temperature from room temperature to 600℃ at a rate of 1.5℃ / min and hold for 4 hours.

[0177] The second step: the temperature is increased from 600℃ to 1000℃ at a rate of 2.5℃ / min and held for 4 hours.

[0178] The third step: the temperature is increased from 1000℃ to 1400℃ at a rate of 3℃ / min and held for 10 hours.

[0179] After the above gradient calcination, the cells are cooled to room temperature in the furnace at a rate of 2.5℃ / min, and then demolded to obtain a tubular half-cell with an electrolyte layer and an anode support layer.

[0180] D) Preparation of cathode:

[0181] d1. Preparation of cathode paste

[0182] Raw material composition:

[0183]

[0184] Preparation: Grind and mix the above raw materials to obtain cathode slurry.

[0185] d2. Apply a small amount of cathode slurry to the surface of the electrolyte layer using a brush, then place it in a box furnace for calcination. The calcination regime is as follows: heat from room temperature to 1000℃ at a rate of 5℃ / min and hold at that temperature for 4 hours. Then cool it to room temperature with the furnace at a rate of 6℃ / min to obtain a tubular SOFC. The anode support layer thickness is 1000μm, the electrolyte layer thickness is 30μm, and the cathode layer thickness is 20μm.

[0186] Example 2

[0187] A) Centrifugal deposition to prepare electrolyte green layer:

[0188] a1. Preparation of electrolyte slurry

[0189] Raw material composition:

[0190] Zirconia-based electrolyte YSZ 4.76%;

[0191] Polyvinyl butyral adhesive 0.14%;

[0192] Ethanol solvent 95.1%.

[0193] Preparation: The above raw materials are ball-milled and mixed to obtain an electrolyte slurry.

[0194] a2. Pour the electrolyte slurry into a corundum tubular mold, then place the tubular mold on a horizontal centrifuge and fix it for high-speed centrifugation at 3000 rpm for 20 minutes. Then, pour out the residual liquid and dry it at room temperature to form an electrolyte green layer.

[0195] B) Centrifugal deposition for preparing the anodic green layer:

[0196] b1. Preparation of anode slurry

[0197] Raw material composition:

[0198]

[0199] Preparation: The above raw materials are ball-milled and mixed to obtain an anode slurry.

[0200] b2. Pour the anode slurry into the tubular mold with the electrolyte green layer obtained in step A), then fix the tubular mold on a horizontal centrifuge and centrifuge at high speed of 1000 rpm for 20 min. Then, pour out the residual liquid and dry it at room temperature to form the anode green layer.

[0201] C) Co-firing:

[0202] The tubular mold with electrolyte green sheet and anode green sheet obtained in step B) is placed in a furnace for gradient calcination. The gradient calcination process is as follows:

[0203] First step: Increase the temperature from room temperature to 600℃ at a rate of 0.5℃ / min and hold for 6 hours.

[0204] The second step: the temperature is increased from 600℃ to 1000℃ at a rate of 1.5℃ / min and held for 8 hours.

[0205] The third step: the temperature is increased from 1000℃ to 1400℃ at a rate of 2.5℃ / min and held for 7 hours.

[0206] After the above gradient calcination, the furnace is cooled to room temperature at a rate of 5℃ / min, and then demolded to obtain a tubular half-cell with an electrolyte layer and an anode support layer.

[0207] D) Preparation of cathode:

[0208] d1. Preparation of cathode paste

[0209] Raw material composition:

[0210]

[0211] Preparation: Grind and mix the above raw materials to obtain cathode slurry.

[0212] d2. Apply a small amount of cathode paste to the surface of the electrolyte layer using a brush, then place it in a box furnace for calcination. The calcination process is as follows: heat from room temperature to 1100°C at a rate of 3°C / min and hold for 2 hours. Then cool it to room temperature with the furnace at a rate of 2.5°C / min to obtain a tubular SOFC. The thickness of each layer is the same as in Example 1.

[0213] Performance testing:

[0214] The electrochemical performance of the battery in Example 1 was tested, and the results are as follows: Figure 3-4 As shown. Among them, Figure 3 The graph shows the discharge curve of the battery in Example 1 at 650°C using hydrogen as fuel. It can be seen that the maximum output power of the obtained battery is 363 mW / cm². -2 It exhibits excellent output characteristics. Figure 4 The image shows the AC impedance spectrum of the battery in Example 1 under open-circuit voltage conditions at 650°C, with a voltage amplitude of 10mW and a frequency range of 10MHz-0.1Hz. It can be seen that the ohmic impedance of the obtained battery is 0.35Ωcm. 2 The polarization impedance is 0.42 Ωcm. 2 It exhibits excellent impedance characteristics.

[0215] Example 1: The morphology of the battery cross-section is as follows Figure 5 As shown, Figure 5 Here is a SEM image of the cross-section of the battery in Example 1, where, Figure 5 (a) and 5(b) are SEM images at different magnifications. It can be seen that the anode has good porosity and the electrolyte has a dense structure.

[0216] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of these embodiments are merely to aid in understanding the method and core ideas of the present invention, including the best mode, and to enable any person skilled in the art to practice the present invention, including manufacturing and using any device or system, and implementing any combined method. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from its principles, and these improvements and modifications also fall within the scope of protection of the claims. The scope of protection of this patent is defined by the claims and may include other embodiments that can be conceived by those skilled in the art. If these other embodiments have structural elements similar to those expressed in the claims, or if they include equivalent structural elements that are not substantially different from those expressed in the claims, then these other embodiments should also be included within the scope of the claims.

Claims

1. A method for preparing a tubular SOFC, characterized in that, Includes the following steps: A) Centrifugal deposition to prepare electrolyte green layer: The electrolyte slurry is added into a tubular mold, and then the tubular mold is placed on a centrifuge for high-speed centrifugation. After centrifugation, the residual liquid is poured out and then dried to form an electrolyte green layer. The above steps are repeated n times for centrifugal deposition until the desired thickness of the electrolyte green layer is obtained; in: n≥1； The high-speed centrifugation speed is 300-3000 rpm, and the time is 2-60 min; The electrolyte slurry comprises the following components in the following mass ratio: Zirconia-based electrolyte: 0.01%–50%; Adhesive 0%–10%; Solvent 40%–99.9%; B) Centrifugal deposition for preparing the anodic green layer: The anode slurry is added into the tubular mold with the electrolyte green layer obtained in step A), and then the tubular mold is placed on a centrifuge for high-speed centrifugation. After centrifugation, the residual liquid is poured out and then dried to form an anode green layer on the surface of the electrolyte green layer. The above steps are followed for a total of m centrifugal depositions until the required thickness of the anodic green sheet is obtained; in: m≥1； The high-speed centrifugation speed is 300-3000 rpm, and the time is 2-60 min; The anode slurry comprises the following components in the following mass ratio: C) Co-firing: The tubular mold with electrolyte green layer and anode green layer obtained in step B) is placed in the furnace for calcination, and then demolded to obtain a tubular half cell with electrolyte layer and anode support layer. Wherein, the calcination is gradient calcination; The gradient calcination process is as follows: First step: Raise the temperature from room temperature to the first temperature, and then hold it at that temperature; the first temperature is 200-800℃, and the holding time is 0.1-30h. The second step involves raising the temperature from the first temperature to the second temperature and then holding it at that temperature; the second temperature is between 600 and 1200°C, and the holding time is between 0.1 and 30 hours. The third step: the temperature is increased from the second temperature to the third temperature, and then held at that temperature; the third temperature is 1200-1600℃, and the holding time is 0.1-30h. In the gradient calcination, the first temperature < the second temperature < the third temperature; D) Preparation of cathode: A cathode layer is prepared on the surface of the electrolytic layer of the tubular half-cell obtained in step C) to obtain a tubular SOFC.

2. The preparation method according to claim 1, characterized in that, In the electrolyte slurry: The zirconium oxide-based electrolyte is YSZ and / or ScYSZ; The adhesive is at least one of polyvinyl alcohol, polyvinyl butyral, ethyl cellulose and acrylic emulsion; The solvent is at least one selected from water, ethanol, xylene, n-butanol, and isopropanol.

3. The preparation method according to claim 1, characterized in that, In the anode slurry: The zirconium oxide-based electrolyte is YSZ and / or ScYSZ; The pore-forming agent is at least one of graphite, starch, and polymethyl methacrylate; The adhesive is at least one of polyvinyl alcohol, polyvinyl butyral, ethyl cellulose and acrylic emulsion; The solvent is at least one selected from water, ethanol, xylene, n-butanol, and isopropanol.

4. The preparation method according to claim 1, characterized in that, In step C): In the first step, the heating rate is 0.1–5 °C / min; In the second step, the heating rate is 0.1–5 °C / min; In the third step, the heating rate is 0.1–5 °C / min.

5. The preparation method according to claim 1, characterized in that, In step C), after calcination, the temperature is lowered before demolding.

6. The preparation method according to claim 1, characterized in that, In step D), the cathode active material in the cathode layer is La. 1-x Sr x Co 1-y Fe y O3, where 0≤x≤1, 0≤y≤1.

7. The preparation method according to claim 1, characterized in that, In step D), the method for preparing the cathode layer specifically includes: coating the cathode slurry onto the surface of the electrolyte layer of the half-cell obtained in step C), and then calcining it to form the cathode layer; The cathode slurry comprises the following components in the indicated mass ratios: The cathode powder is La. 1-x Sr x Co 1-y Fe y O3, where 0≤x≤1, 0≤y≤1.

8. The preparation method according to claim 7, characterized in that, In the cathode slurry: The pore-forming agent is at least one of graphite, starch, and polymethyl methacrylate; The dispersant is at least one of terpineol, fish oil and triethanolamine; The adhesive is at least one of polyvinyl alcohol, polyvinyl butyral, ethyl cellulose, and acrylic emulsion.

9. The preparation method according to claim 7, characterized in that, In step D), the calcination temperature is 500–1300℃, and the holding time is 0–30h.

10. A tubular SOFC prepared by any one of claims 1 to 9.

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