Solid oxide fuel cell electrolyte film

Abstract

The utility model discloses an electrolyte film of a solid oxide fuel cell, which is arranged on the surface of one side of a substrate and comprises a transition layer, a self-repairing layer and a compact layer which are sequentially arranged along the direction far away from the substrate, the transition layer is obtained by preparing a film through a solid-liquid phase forming process and carrying out first sintering, and the self-repairing layer and the compact layer are obtained through a vacuum sputtering coating process at room temperature. According to the utility model, the compact and thin electrolyte film can be obtained at a low preparation temperature, so that the energy consumption cost can be reduced, and commercial application is facilitated. According to the utility model, better film-substrate binding force and film compactness can be realized, pores and cracks are not easy to generate under extreme conditions, the surface of the prepared electrolyte film is smoother, and better interface contact can be realized.

Description

Technical Field

[0001] The utility model relates to the technical field of solid oxide fuel cells, in particular to a solid oxide fuel cell electrolyte film. Background Art

[0002] Solid oxide fuel cells (SOFCs) have the advantages of high energy conversion efficiency, wide fuel adaptability, low cost, etc., making them have broad application potential in scenarios such as large-scale fixed power generation, residential combined heat and power systems, and portable power sources. Among them, the solid oxide electrolyte is one of the key components of SOFCs, and generally needs to have characteristics such as sufficient density, high ionic conductivity, low internal resistance, and strong bonding force. Usually, in order to achieve a high ionic conductivity of the electrolyte material, the operating temperature of SOFCs is mostly 800 - 1000 °C. However, such a high temperature will accelerate material aging, shorten the battery life, and also bring safety hazards. Therefore, preparing a thin-film electrolyte with a thin film thickness, low internal resistance, and high density is one of the methods to reduce the operating temperature of SOFCs.

[0003] At present, common SOFCs electrolyte materials include YSZ, ScSZ, GDC, etc. For traditional solid-liquid phase forming electrolyte manufacturing processes, such as screen printing, spin coating, dip coating, inkjet printing, tape casting, etc., in order to ensure airtightness, the required electrolyte generally has a relatively thick film layer, high internal resistance, and needs to be sintered at a high temperature of 1300 °C - 1400 °C or above, which will consume a high amount of energy. The manufactured electrolyte is also difficult to be applicable to SOFCs operating at a lower temperature, and the electrolyte film layer will undergo varying degrees of deformation after high-temperature sintering. Therefore, there are limitations in large-scale industrial applications.

[0004] In recent years, physical deposition techniques such as sputtering, pulsed laser deposition, and atomic layer deposition have received extensive attention from researchers for their application in manufacturing thin SOFC thin film electrolytes. However, the research results of physical deposition techniques for SOFC thin film electrolytes currently can only achieve better film-substrate adhesion and film densification on surfaces with small pores and relatively flat surfaces. Therefore, it is only limited to the preparation of small-area electrolytes. Once applied to the preparation of large-area thin film electrolytes, problems such as difficulty in achieving uniform deposition of the electrolyte film and poor process reproducibility will cause a significant decline in the electrolyte performance. Moreover, when using vacuum sputtering coating technology to prepare electrolytes, in order to improve the film densification, most depositions need to be carried out at a temperature of about 700 °C. However, high temperatures will bring problems such as energy consumption and equipment aging, with relatively high costs. And sometimes, high-temperature sintering above 1000 °C is required after film deposition, consuming a lot of time and energy costs, which is not conducive to long-term commercial applications. In addition, the electrolytes prepared by existing technologies are prone to generating pores during high-temperature operation at relatively thin thicknesses, making it difficult to be commercially applied in practice. Therefore, there are significant challenges in ensuring the uniformity, airtightness, durability, and electrochemical performance during large-area preparation while reducing the electrolyte thickness and improving the adhesion. Summary of the Utility Model

[0005] The purpose of the present utility model is to overcome the above-mentioned defects existing in the prior art and provide a solid oxide fuel cell electrolyte thin film.

[0006] To achieve the above purpose, the technical solution of the present utility model is as follows:

[0007] The present utility model provides a solid oxide fuel cell electrolyte thin film, which is disposed on one side surface of a substrate and includes a transition layer, a self-healing layer, and a dense layer sequentially arranged in a direction away from the substrate;

[0008] The transition layer is formed into a film by a solid-liquid phase forming process and obtained through first sintering, and the self-healing layer and the dense layer are obtained by a vacuum sputtering coating process at room temperature.

[0009] Furthermore, the substrate includes a single-layer substrate or a multi-layer substrate. The single-layer substrate is a single-layer porous substrate composed of one of porous metal oxides, ceramics, and doped ceramics, and the multi-layer substrate is a multi-layer porous substrate composed of porous metals, alloys, metal oxides, ceramics, doped ceramics, catalysts, and their mixtures in sequence.

[0010] Furthermore, the transition layer is used to seal the pores existing on the surface of the substrate. The self-healing layer is used to reduce the thermal mismatch stress caused by the mismatch of the material thermal expansion coefficients between the electrolyte film and the substrate, and to flatten the surface of the transition layer. The dense layer is used to form the surface of the electrolyte film that ensures airtightness and is dense and pore-free.

[0011] Furthermore, the self-healing layer is formed by depositing first coating particles, and the atomic bond force is weakened through the first vacuum sputtering coating process to provide mechanical compatibility for the electrolyte film, thereby reducing the thermal mismatch stress caused by the mismatch of the material thermal expansion coefficients between the electrolyte film and the substrate, and the surface of the transition layer is flattened through the filling effect of the first coating particles.

[0012] Furthermore, the dense layer is formed by depositing second coating particles, and through the second vacuum sputtering coating process, the particle size of the second coating particles is smaller than that of the first coating particles, and a dense crystal structure that is closely arranged and pore-free is formed on the surface of the self-healing layer as the surface layer of the electrolyte film.

[0013] Furthermore, the electrolyte materials of the transition layer, the self-healing layer, and the dense layer are the same or different; and / or, the transition layer includes one to multiple sub-transition layers, and the electrolyte materials of the multiple sub-transition layers are the same or different; and / or, the self-healing layer includes one to multiple sub-self-healing layers, and the electrolyte materials of the multiple sub-self-healing layers are the same or different; and / or, the dense layer includes one to multiple sub-dense layers, and the electrolyte materials of the multiple sub-dense layers are the same or different.

[0014] Furthermore, the electrolyte materials of the transition layer, the self-healing layer, or the dense layer include at least one of yttria-stabilized zirconia (YSZ), gadolinium-doped ceria (GDC), yttrium-doped ceria (YDC), and samarium-doped ceria (SDC).

[0015] Furthermore, the atomic bond force of the self-healing layer is less than that of the dense layer, and the particle size of the second coating particles is smaller than that of the first coating particles.

[0016] Furthermore, the thickness of the transition layer is 5 - 30 µm.

[0017] Furthermore, the thicknesses of the self-healing layer and the dense layer are 30 nm - 1 µm.

[0018] As can be seen from the above technical solutions, the present utility model forms an electrolyte film on one side surface of a substrate, and the electrolyte film sequentially includes a transition layer, a self-healing layer, and a dense layer. The transition layer is formed by a solid-liquid phase forming process and subjected to a first sintering, and the self-healing layer and the dense layer are obtained by a vacuum sputtering coating process at room temperature, so as to obtain a dense and thin electrolyte film at a relatively low preparation temperature, thereby reducing energy consumption costs and facilitating commercial application. Moreover, by designing the combined electrolyte structure of the transition layer, the self-healing layer, and the dense layer, the present utility model can be applied to the surfaces of various types of substrates (base materials), achieving good film-substrate adhesion and film denseness, not easily generating pores and not easily cracking under extreme conditions, and the surface of the prepared electrolyte film is relatively flat, enabling good interfacial contact. The present utility model has the following advantages:

[0019] (1) By combining the traditional solid-liquid phase forming process with the modern vacuum sputtering coating process, a dense and thin SOFC electrolyte film is obtained, thereby reducing internal resistance and enhancing ionic conductivity to lower the operating temperature of the solid oxide fuel cell.

[0020] (2) Under the condition of thickness reduction, a dense and pore-free SOFC electrolyte film is obtained, ensuring airtightness and effectively preventing direct contact of reaction gases.

[0021] (3) It can be used to prepare SOFC electrolyte films with a relatively large area (for example, 1 - 500 cm 2 ), and the film has good uniformity and excellent process reproducibility over a large area.

[0022] (4) The preparation process of the electrolyte film of the present utility model is carried out at a relatively low temperature. The solid-liquid phase forming process adopts a relatively low sintering temperature (700 - 1200 °C) lower than the conventional sintering temperature, and the vacuum sputtering coating process uses room temperature film formation. After vacuum sputtering coating, a high-quality film can be obtained without post-annealing treatment, thereby reducing energy consumption costs and facilitating commercial application.

[0023] (5) For the electrolyte film prepared by the present utility model, good film-substrate adhesion and film denseness can be achieved on the surfaces of various types of substrates.

[0024] (6) The electrolyte film prepared by the present utility model is not easily generated pores and not easily cracked after multiple high-low temperature thermal cycles.

[0025] (7) The surface roughness of the electrolyte film prepared by the method of the present utility model is small, enabling good upper interface contact. Description of the Drawings

[0026] Figure 1Schematic structural diagram of an electrolyte film of a solid oxide fuel cell according to a preferred embodiment of the present invention.

[0027] Figure 2 Schematic flow diagram of a method for preparing an electrolyte film of a solid oxide fuel cell according to a preferred embodiment of the present invention.

[0028] Figure 3 Schematic comparison diagram of SEM test results on the surfaces of the YSZ transition layer and the electrolyte film prepared in Example 1 of the present invention.

[0029] Figure 4 Schematic comparison diagram of water contact angle test results on the surfaces of the YSZ transition layer and the electrolyte film prepared in Example 1 of the present invention.

[0030] Figure 5 Schematic comparison diagram of SEM test results on the surfaces of the YSZ transition layer and the dense layer prepared in Example 2 of the present invention.

[0031] Among them, Figure 3 The left half of [it] is Figure 3 (a), Figure 3 The right half of [it] is Figure 3 b; Figure 4 The left half of [it] is Figure 4 (a), Figure 4 The right half of [it] is Figure 4 b; Figure 5 The left half of [it] is Figure 5 a, Figure 5 The right half of [it] is Figure 5 b. Detailed implementation manners

[0032] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein shall have the ordinary meanings understood by those of ordinary skill in the art in the field to which the present invention belongs. The words such as "including" used herein mean that the elements or items appearing before this word cover the elements or items listed after this word and their equivalents, without excluding other elements or items.

[0033] When preparing solid oxide fuel cell electrolyte films by traditional methods such as screen printing, spin coating, dip coating, and inkjet printing, in order to ensure airtightness, the thickness of the prepared electrolyte film is generally very thick, with a large internal resistance, which is not suitable for SOFC to operate at a lower working temperature, and needs to be sintered at a high temperature above 1300 - 1400 °C, requiring a relatively high energy consumption. Moreover, the electrolyte film will undergo varying degrees of deformation after high-temperature sintering, which is not conducive to commercial preparation. For the electrolyte films prepared by the existing vacuum sputtering coating technology, when the thickness is relatively thin, pores are likely to be generated during high-temperature operation, making it difficult to commercialize. In addition, it is difficult for the existing technology to achieve uniform deposition of large-area (such as 1 - 500 cm 2 2) SOFC electrolyte films, and the process reproducibility is poor. Most of the existing vacuum sputtering coating processes need to increase the coating temperature (such as increasing to 700 °C) to improve the film layer quality, but high temperature will bring problems such as energy consumption and equipment aging, with a relatively high cost, which is not conducive to long-term commercial application. The existing vacuum sputtering coating process can achieve better film-substrate adhesion and film densification only on a surface with small pores and relatively flat, and is only applicable to small areas, which is not conducive to large-scale production.

[0034] In view of the above problems, the present utility model provides a solid oxide fuel cell electrolyte film and a preparation method. By forming an electrolyte film on one surface of a substrate, the electrolyte film sequentially includes a transition layer, a self-healing layer, and a dense layer, and the transition layer is formed by a solid-liquid phase forming process and subjected to a first sintering, and the self-healing layer and the dense layer are obtained by a vacuum sputtering coating process at room temperature, so as to obtain a dense and thin electrolyte film at a relatively low preparation temperature. The electrolyte film prepared by the method of the present utility model has a relatively thin thickness, can be applicable to complex types of substrates, the preparation process temperature is relatively low, and no high-temperature post-treatment is required, and it is not easy to crack during high-temperature operation.

[0035] The following further elaborates on the specific embodiments of the present utility model in conjunction with the accompanying drawings.

[0036] Refer to Figure 1 FIG.. The present utility model provides a solid oxide fuel cell electrolyte film, and the electrolyte film 2 is disposed on the upper surface shown in the figure of the substrate 1. Moreover, the electrolyte film 2 sequentially includes a transition layer 3, a self-healing layer 4, and a dense layer 5 along the direction away from the upper surface of the substrate 1.

[0037] Among them, the transition layer 3 is obtained by film formation through a solid-liquid phase forming process and then undergoes a first sintering. The self-healing layer 4 and the dense layer 5 are obtained through a vacuum sputtering coating process at room temperature. The transition layer 3 is used to seal the pores existing on the surface of the substrate 1; the self-healing layer 4 is used to reduce the thermal mismatch stress caused by the mismatch of the material thermal expansion coefficients between the electrolyte film 2 and the substrate 1, and to flatten the surface of the transition layer 3; the dense layer 5 is used to form the surface of the dense and pore-free electrolyte film 2 to ensure airtightness.

[0038] In some embodiments, the substrate 1 includes a single-layer substrate or a multi-layer substrate. Among them, the single-layer substrate is a single-layer porous substrate composed of one of porous metal oxides, ceramics, and doped ceramics. The multi-layer substrate is a multi-layer porous substrate composed of porous metals, alloys, metal oxides, ceramics, doped ceramics, catalysts, and their mixtures in sequence. The pore size of the upper surface of the substrate 1 in contact with the electrolyte film 2 is generally required to be smaller than the maximum thickness of the electrolyte film 2 (for example, 32 µm).

[0039] It should be noted that the present utility model is applicable to different types of solid oxide fuel cells, such as electrolyte-supported SOFCs, anode-supported SOFCs, metal-supported SOFCs, cathode-supported SOFCs, ceramic support-supported SOFCs, etc. According to the different forms of battery support, the types and materials of the substrate are also different, and they affect the overall performance of the battery.

[0040] In some embodiments, the transition layer 3 is obtained by film formation through a solid-liquid phase forming process and then undergoes a first sintering. The temperature of the first sintering is a lower sintering temperature of 700 - 1200 °C, which is lower than the conventional sintering temperature. The thickness of the transition layer 3 is 5 - 30 µm. The function of the transition layer 3 is to seal the pores of the substrate 1. However, since the prepared transition layer 3 film is relatively thin and the above-mentioned low-temperature sintering is adopted, there may still be a small number of pores in it (Note: The electrolyte prepared by the traditional solid-liquid phase forming process needs to be sintered at a temperature of 1300 - 1400 °C to reduce pores; the thickness of the YSZ film usually prepared with electrolyte support is usually about 200 µm).

[0041] In some embodiments, the self-healing layer 4 is deposited on the upper surface of the transition layer 3 through the first coating particles formed in the first vacuum sputtering coating process, and the atomic bond force is weakened through the first vacuum sputtering coating process, so that the formed self-healing layer 4 has toughness, making the entire electrolyte film 2 not easily crack under high temperature and extreme environments. The self-healing layer 4 connects the transition layer 3 and the dense layer 5, providing mechanical compatibility for the entire electrolyte film 2, thereby reducing the thermal mismatch stress caused by the mismatch of the material thermal expansion coefficients between the electrolyte film 2 and the substrate 1, and making the entire electrolyte film 2 not easily generate cracks under extreme conditions.

[0042] Moreover, the self-healing layer 4 forms first coating particles with relatively large particle sizes. By utilizing the filling effect of the first coating particles, it plugs the holes that may exist on the surface of the transition layer 3 and acts as a bridge, and also assists in filling the gaps that may exist on the surface of the transition layer 3, thereby weakening the influence of the surface pores of the transition layer 3 and the deformation generated after the first sintering and other morphologies, making the surface of the transition layer 3 flat and obtaining a relatively flat and dense surface of the self-healing layer 4.

[0043] In some embodiments, the dense layer 5 is formed by depositing fine second coating particles with relatively small particle sizes formed in the second vacuum sputtering coating process. Through the second vacuum sputtering coating process, the particle size of the second coating particles is smaller than that of the first coating particles. The second coating particles form a dense crystal structure with no holes and close arrangement on the surface of the self-healing layer 4, and the formed dense layer 5 serves as the surface layer of the entire electrolyte film 2.

[0044] In some embodiments, the electrolyte materials of the transition layer 3, the self-healing layer 4, and the dense layer 5 are the same or different.

[0045] In some embodiments, the transition layer 3 includes one or more sub-transition layers 3, and the electrolyte materials of the multiple sub-transition layers 3 are the same or different.

[0046] In some embodiments, the self-healing layer 4 includes one or more sub-self-healing layers 4, and the electrolyte materials of the multiple sub-self-healing layers 4 are the same or different.

[0047] In some embodiments, the dense layer 5 includes one or more sub-dense layers 5, and the electrolyte materials of the multiple sub-dense layers 5 are the same or different.

[0048] In some embodiments, the electrolyte material of the electrolyte film 2 includes at least one of yttria-stabilized zirconia (YSZ), gadolinium-doped ceria (GDC), yttrium-doped ceria (YDC), and samarium-doped ceria (SDC). Preferably, the electrolyte material of the electrolyte film 2 includes at least one of YSZ and GDC.

[0049] In some embodiments, the electrolyte material of the transition layer 3 includes at least one of YSZ, GDC, YDC, and SDC. Preferably, the electrolyte material of the transition layer 3 includes at least one of YSZ and GDC.

[0050] In some embodiments, the electrolyte material of the self-healing layer 4 includes at least one of YSZ, GDC, YDC, and SDC. Preferably, the electrolyte material of the self-healing layer 4 includes at least one of YSZ and GDC.

[0051] In some embodiments, the electrolyte material of the dense layer 5 includes at least one of YSZ, GDC, YDC, and SDC. Preferably, the electrolyte material of the dense layer 5 includes at least one of YSZ and GDC.

[0052] In some embodiments, by making the sputtering power and process gas pressure of the first vacuum sputtering coating process greater than those of the second vacuum sputtering coating process, and adopting an intermittent coating method during the first vacuum sputtering coating process, the interatomic bonding force of the self-healing layer 4 is made less than that of the dense layer 5, so as to obtain a self-healing layer 4 with weakened interatomic bonding force, and the particle size of the second coating particles is made smaller than that of the first coating particles.

[0053] In some embodiments, the thicknesses of the self-healing layer 4 and the dense layer 5 are 30 nm to 1 µm.

[0054] In some embodiments, no annealing treatment is performed after the first vacuum sputtering coating process and the second vacuum sputtering coating process are completed. That is, after the first vacuum sputtering coating process is completed and the self-healing layer 4 is formed, no annealing treatment is performed. And after the second vacuum sputtering coating process is completed and the dense layer 5 is formed, no annealing treatment is also performed. That is, the electrolyte film 2 of the present invention not only has a relatively low temperature during the preparation process, but also does not require high-temperature post-treatment.

[0055] In some embodiments, after the dense layer 5 is obtained, the electrolyte film 2 is also obtained by performing a low-temperature second sintering. Among them, the temperature of the second sintering is 100 to 800 °C, and the time of the second sintering is within 10 hours. By performing overall low-temperature sintering on the electrolyte film 2 after the dense layer 5 is obtained, the bonding between the transition layer 3, the self-healing layer 4, and the dense layer 5 can be promoted, and the film layer stress can be reduced, so as to obtain a higher-quality electrolyte film 2.

[0056] The following further details a method for preparing a solid oxide fuel cell electrolyte film 2 of the present invention through specific embodiments and in combination with the drawings.

[0057] A method for preparing a solid oxide fuel cell electrolyte film 2 of the present invention includes:

[0058] Providing a substrate 1;

[0059] Forming an electrolyte film 2 on one side surface of the substrate 1, so that the electrolyte film 2 includes a transition layer 3, a self-healing layer 4, and a dense layer 5 formed in sequence along the direction away from the substrate 1;

[0060] Among them, the transition layer 3 is obtained by film formation through a solid-liquid phase forming process and first sintering, and the self-healing layer 4 and the dense layer 5 are obtained through a vacuum sputtering coating process at room temperature.

[0061] Reference Figure 2 In some embodiments, a method for preparing a solid oxide fuel cell electrolyte film 2 of the present utility model can be used to prepare, for example Figure 1 a solid oxide fuel cell electrolyte film 2 of the present utility model as shown, and includes the following steps:

[0062] Step S1: Form a transition layer 3 on the surface of the substrate 1.

[0063] Using electrolyte powder, binder and solvent as raw materials, uniformly mix them, and through a solid-liquid phase forming process, prepare a thinner film on the porous surface of the substrate 1. Then, sinter at a lower sintering temperature lower than the conventional sintering temperature (first sintering) to obtain a thinner transition layer 3, as Figure 1 shown.

[0064] The transition layer 3 is used to seal the pores on the surface of the substrate 1. Since the prepared transition layer 3 film is thinner and the above low-temperature sintering is used, there may still be a small amount of pores in it. While the electrolyte prepared by the traditional solid-liquid phase forming process needs to be sintered at a temperature of 1300 - 1400 °C to reduce pores; and the YSZ film prepared by electrolyte support is usually about 200 μm thick.

[0065] In some embodiments, the substrate 1 includes but is not limited to a single-layer or multi-layer porous substrate 1 made of porous metal, alloy, metal oxide, ceramic, doped ceramic, catalyst and their mixtures. The pore size of the upper surface of the substrate 1 in contact with the electrolyte film 2 is generally required to be less than the maximum thickness of the electrolyte film 2 (for example, 32 µm).

[0066] In some embodiments, the solid-liquid phase forming process includes one or a combination of more of tape casting, screen printing, slurry spin coating, electrophoretic deposition, slurry 3D printing, dry forming, slip casting, centrifugal casting, sol-gel method, spraying, spray pyrolysis method. Preferably, the solid-liquid phase forming process includes tape casting, screen printing, and slurry spin coating methods.

[0067] In some embodiments, the electrolyte powder raw material includes one of yttria-doped zirconia (YSZ), gadolinia-doped ceria (GDC), yttria-doped ceria (YDC), samarium-doped ceria (SDC), etc.

[0068] The binder includes one of ethyl cellulose, nitrocellulose, carboxymethyl cellulose, polyvinyl alcohol, polyvinyl butyral, etc.

[0069] The solvent includes one of terpineol, 1,4-butyrolactone, glycerol, dibutyl phthalate, tributyl citrate, etc.;

[0070] In some embodiments, the first sintering temperature is 700 - 1200 °C. Preferably, the first sintering temperature is 800 - 1100 °C. More preferably, the first sintering temperature is 900 - 1100 °C.

[0071] In some embodiments, the thickness of the transition layer 3 is 5 - 30 µm. Preferably, the thickness of the transition layer 3 is 5 - 25 µm. More preferably, the thickness of the transition layer 3 is 5 - 20 µm.

[0072] Step S2: Form a self - healing layer 4 on the surface of the transition layer 3.

[0073] Under room - temperature conditions, using the electrolyte raw material as the target, through the first vacuum sputtering coating process, a self - healing layer 4 thinner than the transition layer 3 formed by the deposition of the first coating particles is formed on the surface of the transition layer 3.

[0074] In some embodiments, the electrolyte raw material target used in the first vacuum sputtering coating process includes, but is not limited to, one of Y / Zr alloy, Gd / Ce alloy, Y / Ce alloy, Sm / Ce alloy, yttria - stabilized zirconia (YSZ), gadolinium - doped ceria (GDC), yttria - doped ceria (YDC), samarium - doped ceria (SDC). Preferably, the electrolyte raw material target used in the first vacuum sputtering coating process includes one of Y / Zr alloy, Gd / Ce alloy, YSZ, GDC.

[0075] In some embodiments, the first vacuum sputtering coating type includes one or a combination of more than one of direct - current sputtering, radio - frequency sputtering, direct - current reactive sputtering, radio - frequency reactive sputtering, direct - current pulsed sputtering.

[0076] In some embodiments, under room - temperature conditions, first perform ion cleaning on the substrate 1 coated with the transition layer 3, and then use the first vacuum sputtering coating process, with the above - mentioned electrolyte raw material as the target, to deposit the self - healing layer 4 on the surface of the transition layer 3.

[0077] Both the ion cleaning and the first vacuum sputtering coating are carried out at room temperature without heating.

[0078] After completing the first vacuum sputtering coating process to obtain the self - healing layer 4, no annealing treatment is performed.

[0079] The self-healing layer 4 is a film layer formed by depositing first coating particles mainly composed of large coating particles and medium coating particles. During the sputtering process, by regulating the sputtering process to weaken the interatomic bonding, the formed self-healing layer 4 has toughness and is not prone to cracking under high temperature and extreme environments. The self-healing layer 4 connects the transition layer 3 and the dense layer 5. The self-healing layer 4 can provide mechanical compatibility for the entire electrolyte film layer structure, reduce the thermal mismatch stress caused by the mismatch of the thermal expansion coefficients between the electrolyte and the substrate 1, and make the entire electrolyte thin film 2 not prone to cracks under extreme conditions. Among them, the large coating particles in the self-healing layer 4 play the role of plugging holes and bridging, and the medium coating particles assist in filling the gaps, thereby weakening the influence of the surface pores of the transition layer 3, deformation after sintering and other morphologies, and obtaining a relatively flat and dense surface of the self-healing layer 4. Therefore, it can be used to prepare SOFC electrolyte thin films 2 with a relatively large area (for example, 1-500 cm 2 ), and the film has good uniformity and excellent process reproducibility over a large area.

[0080] In some embodiments, the process parameters related to the first vacuum sputtering coating process include:

[0081] The sputtering power of the target is relatively large, being 1-10 W / cm 2 , preferably 2-8 W / cm 2 , and further preferably 2-6 W / cm 2 .

[0082] During the process, the process gas pressure is relatively high, being 0.3-2 Pa, preferably 0.3-1.5 Pa, and further preferably 0.3-1 Pa; the flow rate of the process gas Ar is 20-500 sccm, preferably 20-400 sccm, and further preferably 20-300 sccm; the flow rate of the process gas O 2 during the process is below 300 sccm, preferably below 200 sccm, and further preferably below 100 sccm; the O 2 / Ar mixing ratio is 1 / 300-1 / 1, preferably 1 / 200-1 / 3, and further preferably 1 / 100-1 / 4; the sputtering coating rate is relatively fast, being 20-300 nm / min, preferably 20-200 nm / min, and further preferably 20-100 nm / min.

[0083] The target-substrate distance is 2-30 cm, preferably 3-25 cm, and further preferably 4-20 cm.

[0084] The bias voltage is 0--1200 V, preferably -20 V--800 V, and further preferably -50 V--600 V; the bias voltage duty cycle is 1-100%, preferably 5-80%, and further preferably 10-60%.

[0085] Among them, the above coating process is an intermittent coating process, which is realized by intermittently turning on and off the working gas, and O 2 and Ar are mixed in a gas mixing tank and then intermittently introduced into the sputtering chamber. The ratio of the process pause time to the total process time is 1 / 50 to 1 / 3, preferably 1 / 40 to 1 / 3, and further preferably 1 / 30 to 1 / 3.

[0086] The obtained self-healing layer 4 is as Figure 1 shown. The thickness of the self-healing layer 4 is 30 nm to 1 µm, preferably 100 nm to 1 µm, and further preferably 150 nm to 900 nm.

[0087] Step S3: Form a dense layer 5 on the surface of the self-healing layer 4 to form the electrolyte film 2.

[0088] Under room temperature conditions, using the electrolyte raw material as the target, through the second vacuum sputtering coating process, a dense layer 5 thinner than the transition layer 3 formed by the deposition of the second coating particles is continuously formed on the surface of the self-healing layer 4.

[0089] In some embodiments, the electrolyte raw material target used in the second vacuum sputtering coating process includes, but is not limited to, one of Y / Zr alloy, Gd / Ce alloy, Y / Ce alloy, Sm / Ce alloy, yttria-stabilized zirconia (YSZ), gadolinium-doped ceria (GDC), yttria-doped ceria (YDC), and samarium-doped ceria (SDC). Preferably, the electrolyte raw material target used in the second vacuum sputtering coating process includes one of Y / Zr alloy, Gd / Ce alloy, YSZ, and GDC.

[0090] In some embodiments, the second vacuum sputtering coating type includes one or a combination of direct current sputtering, radio frequency sputtering, direct current reactive sputtering, radio frequency reactive sputtering, and direct current pulsed sputtering.

[0091] The second vacuum sputtering coating is carried out at room temperature without heating. After the dense layer 5 is obtained by completing the second vacuum sputtering coating process, no annealing treatment is performed.

[0092] The dense layer 5 is a film layer composed of the deposition of fine second coating particles. The dense layer 5 uses sputtering to generate fine particles and is deposited on the self-healing layer 4 at a slightly lower deposition rate to form a dense crystal structure with a tight arrangement and no pinholes.

[0093] In some embodiments, the relevant process parameters during the second vacuum sputtering coating process include:

[0094] The sputtering power of the target is small, which is 0.01 to 3 W / cm 2 , preferably 0.05 to 2.5 W / cm2 and more preferably 0.1~2 W / cm 2 .

[0095] During the process, the process gas pressure is relatively low, being 0.05~1 Pa, preferably 0.05~0.8 Pa, and more preferably 0.05~0.5 Pa; the flow rate of the working gas Ar is 20~500 sccm, preferably 20~400 sccm, and more preferably 20~300 sccm; during the process, the flow rate of the working gas O 2 is below 300 sccm, preferably below 200 sccm, and more preferably below 100 sccm; the O 2 / Ar mixing ratio is 1 / 300~1 / 1, preferably 1 / 200~1 / 3, and more preferably 1 / 100~1 / 4; the sputtering coating rate is relatively slow, being 0.5~50 nm / min, preferably 1~45 nm / min, and more preferably 5~30 nm / min.

[0096] The target-substrate distance is 2~30 cm, preferably 3~25 cm, and more preferably 4~20 cm; the bias voltage is +200 V~-1200 V, preferably -20 V~-800 V, and more preferably -50 V~-600 V; the bias duty cycle is 1~100%, preferably 5%~80%, and more preferably 10%~60%.

[0097] The obtained dense layer 5 is as Figure 1 shown. The thickness of the dense layer 5 is 30 nm~1 µm, preferably 50 nm~800 nm, and more preferably 100 nm~600 nm.

[0098] When preparing the self-healing layer 4 and the dense layer 5, the electrolyte raw material is used as the target, and they are prepared by the method of vacuum sputtering coating. The main difference lies in the different preparation processes.

[0099] Among them, by making the sputtering power and process gas pressure of the first vacuum sputtering coating process greater than those of the second vacuum sputtering coating process, and adopting an intermittent coating method during the first vacuum sputtering coating process, the interatomic bonding force of the self-healing layer 4 deposited is made less than the interatomic bonding force of the dense layer 5 deposited, so as to obtain a self-healing layer 4 with weakened interatomic bonding force, and making the particle size of the second coating particles smaller than that of the first coating particles, so as to provide mechanical compatibility for the electrolyte film 2 through the self-healing layer 4, reduce the thermal mismatch stress caused by the mismatch of the material thermal expansion coefficients between the electrolyte film 2 and the substrate 1, and level the surface of the transition layer 3 through the filling effect of the first coating particles. By making the sputtering power and process gas pressure of the second vacuum sputtering coating process less than those of the first vacuum sputtering coating process, the deposition rate and particle size of the second coating particles are reduced, and a dense crystal structure without holes and arranged tightly is formed on the surface of the self-healing layer 4 as the surface layer of the electrolyte film 2. Therefore, in the case of reduced thickness, a dense and hole-free SOFC electrolyte film 2 is obtained, ensuring airtightness and effectively preventing the direct contact of reaction gases. Moreover, the surface roughness of the electrolyte film 2 prepared by the method of the present utility model is small, and good upper interface contact can be achieved.

[0100] It should be noted that the sputtering power for preparing the self-healing layer 4 is higher than that for preparing the dense layer 5, based on the principle that the higher the sputtering power used, the greater the sputtering amount of the target material, the more large particles are sputtered, and the faster the film layer deposition rate. As a result, it is difficult for the first coating particles to migrate and diffuse on the surface of the substrate (transition layer 3), and it is easy to form layered or island-like clusters with relatively weak interatomic bonding forces, but it can achieve the functions of plugging holes, bridging, and filling gaps. While the sputtering power for preparing the dense layer 5 is low, the sputtering amount of the target material is small, and it is easier to form fine second coating particles, so that the film layer of the dense layer 5 is denser.

[0101] Furthermore, during the preparation of the self-healing layer 4, the sputtering gas pressure is higher than that during the preparation of the dense layer 5. The gas pressure is mainly determined by the background vacuum and the working gas flow rate during the coating process. During the preparation of the self-healing layer 4, the working gas is introduced in an intermittent manner, thereby realizing intermittent coating. The formed self-healing layer 4 has a weak atomic bonding force and plays a role in providing mechanical compatibility for the entire film layer structure of the electrolyte film 2 when connecting the transition layer 3 and the dense layer 5. While during the preparation of the dense layer 5, the vacuum degree is high and the working gas is less, the mean free path of gas molecules increases, and it is not easy to form island-like clusters, and it is relatively easy to form a uniform and dense film layer.

[0102] Further, the sputtering coating rate when preparing the self-healing layer 4 is higher than that when preparing the dense layer 5. To weaken the influence of the pores on the surface of the transition layer 3 and obtain a film layer with weak atomic bonding force, a relatively fast coating rate is required when preparing the self-healing layer 4. When preparing the dense layer 5, in order to facilitate the subsequent processes of the battery, a flat, uniform and dense plane needs to be formed. Therefore, fine second coating particles need to be generated, so that they have enough time to migrate and diffuse after deposition. Therefore, a lower coating rate needs to be provided when preparing the dense layer 5.

[0103] The present utility model provides a low-temperature preparation method for a self-healable large-area solid oxide fuel cell electrolyte film 2. In order to reduce the preparation temperature and the overall thickness of the electrolyte film, the method of the present utility model combines the traditional solid-liquid forming process with the vacuum sputtering coating process, so as to obtain a relatively dense and thin-film electrolyte at a lower preparation temperature, thereby reducing the energy consumption cost and facilitating commercial application.

[0104] The present utility model also designs a combined electrolyte structure of a self-healing layer 4, a transition layer 3, and a dense layer 5, so that the preparation process is applicable to the surfaces of various types of substrates, and good film-substrate bonding force and film denseness can be achieved. Under extreme conditions (for example, after multiple high-low temperature cycles), pores are not easily generated and cracking is not likely to occur. Moreover, the surface of the prepared electrolyte film 2 is relatively flat, and good interfacial contact can be achieved.

[0105] In some embodiments, it further includes step S4: after forming the dense layer 5, the obtained electrolyte film 2 is subjected to a second sintering.

[0106] After preparing the above-mentioned transition layer 3, self-healing layer 4, and dense layer 5, the electrolyte film 2 is subjected to a low-temperature second sintering to promote the bonding between the film layers and reduce the film layer stress, thereby obtaining a higher-quality electrolyte film 2.

[0107] In some embodiments, the temperature of the second sintering is 100-800 °C, preferably 200-800 °C, and further preferably 300-700 °C.

[0108] In some embodiments, the time of the second sintering is less than 10 hours, preferably less than 5 hours, and further preferably less than 3 hours.

[0109] Example 1

[0110] (1) Preparation of the AAO / NiO-YSZ porous substrate 1: Prepare a porous alumina substrate with a size of 20 cm × 20 cm. After washing and drying, the NiO-YSZ anode material is deposited on the porous alumina substrate by reactive co-sputtering of Ni and Y-Zr alloy targets to obtain the porous substrate 1.

[0111] (2) Preparation of YSZ transition layer 3: Mix the ball-milled YSZ powder and the terpineol ethyl cellulose binding solvent in a ratio of 7:3, stir evenly to obtain the YSZ slurry; uniformly coat the YSZ slurry on the AAO / NiO-YSZ porous substrate 1 by screen printing method, and then carry out low-temperature sintering of the YSZ transition layer 3 at 1100 °C for 3 h. The obtained YSZ transition layer 3 has a thickness of 10 µm. The SEM test results of its surface are as Figure 3 shown in (a), the water contact angle test CA is 44.442, as Figure 4 shown in (a). It can be seen that the electrolyte membrane with only the transition layer 3 prepared still has pores and is relatively hydrophilic.

[0112] (3) Preparation of YSZ self-healing layer 4: Under room temperature conditions, first perform ion cleaning on the substrate 1 deposited with the YSZ transition layer 3, and then use "8mol% Y 2 O 3 -92mol% ZrO 2 " as the mixed target, carry out radio frequency magnetron sputtering, the sputtering power is 5 W / cm 2 , the working gas pressure is 0.5 Pa, the Ar flow rate is 200 sccm, the O 2 flow rate is 30 sccm, the coating rate is 30 nm / min, the target-substrate distance is 8 cm, the bias voltage is -500 V, the duty cycle is 40%, the coating process is intermittent, the process is carried out for 5 min and paused for 1 min alternately. The obtained self-healing layer 4 has a thickness of 600 nm.

[0113] (4) Preparation of YSZ dense layer 5: Use "8mol% Y 2 O 3 -92mol% ZrO 2 " as the target, under room temperature conditions, carry out radio frequency magnetron sputtering, the sputtering power is 1 W / cm 2 , the working gas pressure is 0.2 Pa, the Ar flow rate is 50 sccm, the coating rate is 15 nm / min, the target-substrate distance is 8 cm, the bias voltage is -500 V, the duty cycle is 30%. The obtained dense layer 5 has a thickness of 300 nm.

[0114] After that, no post-treatment is required to obtain a flat and dense YSZ electrolyte thin film 2, and its structure can be referred to Figure 1 , the SEM test results of its surface are as Figure 3 shown in b, the water contact angle test CA is 97.37, as Figure 4 shown in b. The obtained electrolyte thin film 2 is dense and pore-free and relatively hydrophobic. The prepared YSZ electrolyte thin film 2 is heat-treated at 650 °C for 100 h and no cracking is observed.

[0115] Example 2

[0116] (1) Preparation of NiO-YSZ porous substrate 1: A NiO-YSZ porous support substrate 1 with a size of 20 cm × 20 cm was prepared by the tape casting method.

[0117] (2) Preparation of YSZ transition layer 3: The ball-milled YSZ, terpineol carboxymethyl cellulose binder solvent were mixed in a ratio of 6:4, and stirred evenly to obtain a YSZ slurry; the YSZ slurry was evenly coated on the NiO-YSZ porous substrate 1 by spraying method, and then low-temperature sintered at 900 °C for 2 h. The obtained YSZ transition layer 3 had a thickness of 15 µm. The SEM test results are as Figure 5 shown in a.

[0118] (3) Preparation of YSZ self-healing layer 4: Under room temperature conditions, the substrate 1 deposited with the YSZ transition layer 3 was first subjected to ion cleaning, and then "8 mol% Y 2 O 3 -92 mol% ZrO 2 " was used as the target for radio frequency magnetron sputtering. The sputtering power was 3 W / cm 2 , the working gas pressure was 0.6 Pa, the Ar flow rate was 200 sccm, the O 2 flow rate was 50 sccm, the coating rate was 40 nm / min, the target-substrate distance was 8 cm, the bias voltage was -500 V, the duty cycle was 40%, the coating process was intermittent, the process was carried out for 5 min and paused for 30 s alternately. The obtained self-healing layer 4 had a thickness of 800 nm.

[0119] (4) Preparation of YSZ dense layer 5: Using "8 mol% Y 2 O 3 -92 mol% ZrO 2 " as the target, radio frequency magnetron sputtering was carried out at room temperature. The sputtering power of the electrolyte film was 0.5 W / cm 2 , the working gas pressure was 0.1 Pa, the Ar flow rate was 100 sccm, the O 2 flow rate was 25 sccm, the coating rate was 20 nm / min, the target-substrate distance was 8 cm, the bias voltage was -500 V, the duty cycle was 30%. The obtained dense layer 5 had a thickness of 400 nm.

[0120] (5) Low-temperature sintering was carried out at 500 °C for 1 h to obtain a uniform and dense YSZ electrolyte film 2, and its structure can be referred to Figure 1 , and the SEM test results are as Figure 5 shown in b. The prepared YSZ electrolyte film 2 was heat-treated at 650 °C for 100 h and no cracks were observed.

[0121] In summary, in the present utility model, an electrolyte thin film 2 is formed on one side surface of a substrate 1, the electrolyte thin film 2 sequentially includes a transition layer 3, a self-healing layer 4 and a dense layer 5, the transition layer 3 is formed by a solid-liquid phase forming process and subjected to first sintering, the self-healing layer 4 and the dense layer 5 are obtained by a vacuum sputtering coating process at room temperature, so as to obtain a dense and thin electrolyte thin film 2 at a relatively low preparation temperature, thereby reducing the energy consumption cost and being conducive to commercial application. Moreover, in the present utility model, by designing the combined electrolyte structure of the transition layer 3, the self-healing layer 4 and the dense layer 5, it can be applied to the surfaces of various types of substrates 1 (base materials), good film-substrate bonding force and film denseness can be achieved, pores are not easily generated under extreme conditions, cracking is not easy, and the surface of the obtained electrolyte thin film 2 is relatively flat, and good interface contact can be achieved. Applying the SOFC electrolyte thin film 2 of the present utility model can reduce the internal resistance and improve the ionic conductivity, thereby reducing the operating temperature of the SOFC.

[0122] Although the embodiments of the present utility model have been described in detail above, it is obvious to those skilled in the art that various modifications and changes can be made to these embodiments. However, it should be understood that such modifications and changes are all within the scope and spirit of the present utility model described in the claims. Moreover, the present utility model described herein may have other embodiments and can be implemented or realized in various ways.

Claims

1. A solid oxide fuel cell electrolyte membrane, characterized in that: The electrolyte film is arranged on one side surface of the substrate, and comprises a transition layer, a self-repairing layer and a dense layer which are arranged in sequence in a direction away from the substrate; The transition layer is formed by a solid-liquid phase forming process and then subjected to a first sintering process to obtain the self-repairing layer and the dense layer are obtained by a vacuum sputtering coating process at room temperature.

2. The solid oxide fuel cell electrolyte membrane according to claim 1, characterized in that: The substrate includes a single-layer substrate or a multi-layer substrate. The single-layer substrate is a single-layer porous substrate composed of one of porous metal oxides, ceramics, and doped ceramics. The multi-layer substrate is a multi-layer porous substrate composed of porous metals, alloys, metal oxides, ceramics, and doped ceramics in sequence.

3. The solid oxide fuel cell electrolyte membrane according to claim 1, characterized in that: The transition layer is used to seal the pores on the surface of the substrate, the self-healing layer is used to reduce the thermal mismatch stress between the electrolyte film and the substrate due to the mismatch in material thermal expansion coefficients, and to smooth the surface of the transition layer, and the dense layer is used to form a dense and pore-free surface of the electrolyte film to ensure air tightness.

4. The solid oxide fuel cell electrolyte membrane according to claim 3, characterized in that: The self-healing layer is deposited by first coating particles, and the interatomic bonding force is weakened by a first vacuum sputtering coating process, thereby providing mechanical compatibility for the electrolyte film, thereby reducing the thermal mismatch stress between the electrolyte film and the substrate caused by the mismatch of material thermal expansion coefficients, and the surface of the transition layer is smoothed by the filling effect of the first coating particles.

5. The solid oxide fuel cell electrolyte membrane according to claim 4, characterized in that: The dense layer is formed by depositing second coating particles, and through a second vacuum sputtering coating process, the particle size of the second coating particles is made smaller than the particle size of the first coating particles, forming a dense crystal structure with dense arrangement and no holes on the surface of the self-repairing layer as the surface layer of the electrolyte film.

6. The solid oxide fuel cell electrolyte membrane according to claim 5, characterized in that: The electrolyte materials of the transition layer, the self-repairing layer and the dense layer are the same or different; and / or the transition layer includes one or more sub-transition layers, and the electrolyte materials of the multiple sub-transition layers are the same or different; and / or the self-repairing layer includes one or more sub-self-repairing layers, and the electrolyte materials of the multiple sub-self-repairing layers are the same or different; and / or the dense layer includes one or more sub-dense layers, and the electrolyte materials of the multiple sub-dense layers are the same or different.

7. The solid oxide fuel cell electrolyte membrane according to claim 5 or 6, characterized in that: The interatomic bonding force of the self-repairing layer is smaller than the interatomic bonding force of the dense layer, and the particle size of the second coating particles is smaller than the particle size of the first coating particles.

8. The solid oxide fuel cell electrolyte membrane according to claim 1, characterized in that: The thickness of the transition layer is 5-30 μm.

9. The solid oxide fuel cell electrolyte membrane according to claim 1, characterized in that: The thickness of the self-repairing layer and the dense layer is 30nm~1µm.

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