Method for improving combination of SOFC cathode and electrolyte based on Ag enhanced interface

Abstract

The invention discloses a method for improving combination of an SOFC cathode and an electrolyte based on an Ag enhanced interface. The method mainly comprises the following steps: preparing a cathode material and corresponding cathode slurry; a cathode material and silver powder are mixed to prepare'cathode + Ag 'composite slurry; coating the'cathode + Ag 'composite slurry on the electrolyte surface of the SOFC half cell, and drying; continuously coating a layer of pure cathode slurry on the anode, and drying; and calcining at 980-1200 DEG C for 1-5 hours to obtain a single cell with the structure of an anode electrolyte Ag enhanced interface cathode. According to the method, the Ag particles in the cathode are melted and settled to the cathode / electrolyte interface at the calcining temperature higher than the melting point (-962 DEG C) of Ag, and the joint of the cathode and the electrolyte is partially coated, so that the Ag enhanced interface capable of improving two-phase combination is constructed. The Ag enhanced interface can effectively improve the problem of weak interface bonding of the SOFC cathode / electrolyte, increase the effective contact area of the interface, and enhance the ORR activity and conductivity of the cathode at the same time, thereby significantly improving the electrochemical performance and durability of the battery.

Description

Technical Field

[0001] The present invention belongs to the technical fields of inorganic non-metallic ceramic interface engineering and energy power technology, and particularly relates to a method for improving the bonding between the cathode and electrolyte of a SOFC by enhancing the interface with Ag, that is, a preparation method for an Ag-enhanced interface used to improve the bonding between the cathode and electrolyte of a solid oxide fuel cell (SOFC); namely, a new method for enhancing the bonding between the cathode and electrolyte and the cell performance by melting Ag particles on the cathode and partially coating the connection between the cathode and electrolyte to construct an Ag-enhanced interface. Background Art

[0002] Solid oxide fuel cell (SOFC) is an electrochemical device that directly converts the chemical energy in fuel into electrical energy. It has the advantages of high energy conversion efficiency, zero emissions, low cost, and diverse fuels, and is one of the most promising distributed power sources at present. To promote the commercial progress of SOFC, enhance its competitive advantage, reducing its operating temperature and extending its service life are the top priorities at present. As the site of the rapid oxygen reduction reaction (ORR), the bonding quality at the cathode / electrolyte interface is an important factor determining the performance of SOFC, and the evolution of the interface structure also plays a key role in the battery durability. However, a large amount of work in recent years has shown that SOFC still has the inherent defect of weak bonding at the cathode / electrolyte interface, which limits its development and application. This defect is mainly caused by the following two reasons: 1) The thermal expansion coefficient (TEC) of cathode materials is generally higher than that of electrolytes. The interfacial thermal stress generated during the high-temperature operation of the battery due to the interlayer thermal mismatch is one of the important factors that damage the bonding at the cathode / electrolyte interface; 2) The surface activity of the electrolyte after high-temperature annealing decreases, and the flat and smooth surface is not conducive to its bonding with the cathode, jointly resulting in problems such as weak bonding at the cathode / electrolyte and high interfacial resistance. To solve the problem of weak interfacial bonding, many attempts and efforts have been made in the field and remarkable results have been achieved, which can be mainly divided into the following three directions: 1) Starting from the cathode, reducing the cathode TEC (i: Zhang Y, Chen B, Guan D, et al. Thermal-expansion offset for high-performance fuel cell cathodes[J]. Nature, 2021, 591(7849): 246-251; ii: Cai Bin, Lu Fei, Yang Mengjie, et al. A novel composite cathode material containing negative thermal expansion material and its application in preparing SOFC[P]. Chinese invention patent, CN111403754B); 2) Starting from the electrolyte, activating the electrolytic surface and increasing the surface roughness (Bian W, Wu W, Wang B, et al. Revitalizing interface in protonic ceramic cells by acid etch[J]. Nature, 2022, 604(7906): 479-485); 3) Starting from the cathode / electrolyte interface, constructing an interfacial interlayer to enhance the interfacial bonding. This application focuses on introducing the work in this aspect.

[0003] The design and construction of the cathode / electrolyte interface interlayer usually starts from the following three goals: 1) enhancing the bonding strength of the cathode / electrolyte interface; 2) enhancing the ORR ability or ion-electron transport rate at the interface; 3) preventing interfacial chemical diffusion. For this reason, the materials used for the interface interlayer are usually cathode materials (Choi S, Kucharczyk C J, Liang Y, et al. Exceptional power density and stability at intermediate temperatures in protonic ceramic fuel cells[J]. Nature Energy, 2018, 3(3): 202-210), electrolyte materials (Nguyen X D, Lee S W, Kim S J, et al. Boosting electrochemical performance via extra-role of La-Doped CeO 2-δ interlayer for “Oxygen Provider” at high-current SOFC operation[J]. Advanced Science, 2024, 11(46): 2402348), and cathode + electrolyte composite materials (Umer M A, Cheng C Y, Lai B R, et al. Growth of Gd 0.3 Ca 2.7 Co 3.82 Cu 0.18 O 9-δ - BaCe 0.6 Zr 0.2 Y 0.2 O 3-δBulk Heterojunction Cathode Interlayer by Pulsed Laser Deposition for Enhancing Protonic Solid Oxide Fuel Cell Performance[J]. Applied Surface Science, 2023, 638: 158139). These types. The interfacial interlayers constructed from these materials have all been proven to effectively enhance the cathode / electrolyte interfacial bonding and improve cell performance. In addition, metal intermediate functional layers have also been innovatively used to enhance the SOFC cathode / electrolyte interface, achieving significant gain effects. Choi et al. (i: Choi M, Hwang S, Kim S J, et al. Rational design of a metallic functional layer for high-performance solid oxide fuel cells[J]. ACS Applied Energy Materials, 2019, 2(6): 4059-4068; ii: Choi M, Hwang S, Byun D, et al. Enhanced charge transfer with Ag grids at electrolyte / electrode interfaces in solid oxide fuel cells[J]. Journal of Materials Chemistry A, 2016, 4(12): 4420-4424.) introduced metal intermediate functional layers with Al, Ni, Ag grid structures at the SOFC cathode / electrolyte interface using a printing technique. The results showed that among several metals, the Ag functional layer exhibited the best enhancement effect and performance improvement. The comprehensive results proved that the addition of the Ag functional layer could effectively increase the cathode / electrolyte interfacial bonding strength, while enhancing the cathode ORR activity and conductivity, thus significantly improving the cell performance and stability.

[0004] Although the metal intermediate functional layer prepared by Choi et al. has achieved significant gain effects, there are still some deficiencies. For example, the grid gap of this metal intermediate layer reaches 50 - 400 μm, while the cathode particle size is usually in the micrometer range (<5 μm) and even in the sub-micrometer range (100 nm - 1 μm). Obviously, the designed metal intermediate layer in this work has limited enhancement effect on the local cathode / electrolyte microinterface. Therefore, to make up for the deficiencies of the current metal intermediate layer-related work and further enhance the cathode / electrolyte interface bonding, this application innovatively proposes a new method of constructing an Ag-enhanced interface by melting cathode Ag particles. Summary of the Invention

[0005] To solve the above problems existing in the prior art in the field, the present invention provides a method for improving the bonding between the cathode and electrolyte of a SOFC based on an Ag-enhanced interface, which is a method for improving the bonding between the cathode and electrolyte of a solid oxide fuel cell (SOFC) by melting cathode Ag particles to construct an Ag-enhanced interface; that is, an additional "cathode + Ag" layer is added between the cathode and electrolyte layers, and by using a calcination temperature higher than the melting point of Ag, the Ag particles in the "cathode + Ag" layer are melted and settled to the cathode / electrolyte interface, and partially coat the connection between the cathode and electrolyte, thereby constructing an Ag-enhanced interface that can improve the bonding of the two, and obtaining a single cell with the structure of anode|electrolyte|Ag-enhanced interface|cathode To achieve the above object, the present invention adopts the following technical solutions: A method for improving the bonding between the cathode and electrolyte of a SOFC based on an Ag-enhanced interface, which adds an additional "cathode + Ag" layer between the cathode and electrolyte layers; and by using a calcination temperature higher than the melting point of Ag, the Ag particles in the "cathode + Ag" layer are melted and settled to the cathode / electrolyte interface, and partially coat the connection between the cathode and electrolyte, thereby constructing an Ag-enhanced interface that can improve the bonding of the two, and obtaining a single cell with the structure of anode|electrolyte|Ag-enhanced interface|cathode.

[0006] Specifically, the thickness of the "cathode + Ag" layer can be 2 - 10 μm.

[0007] Specifically, the Ag content in the "cathode + Ag" layer can be 5 - 40 wt.%.

[0008] Further, the Ag raw material for preparing the "cathode + Ag" layer is silver powder. Preferably, the particle size of the silver powder can be 50 nm - 2 μm.

[0009] The present invention provides a preparation method of a SOFC containing an Ag-enhanced interface, which includes the following steps: S1: Prepare the cathode material and the corresponding cathode slurry; S2: Prepare a "cathode + Ag" composite slurry by mixing the cathode material obtained in S1 with silver powder; S3: Coat a layer of the "cathode + Ag" composite slurry obtained in S2 on the surface of the electrolyte of the SOFC half-cell and dry it; S4: Continuously coat a layer of the cathode slurry obtained in S1 on the basis of S3 and dry it; S5: Calcinate the half-cell obtained in S4 at 980 - 1200 °C for 1 - 5 h to obtain an SOFC single cell with the structure of anode | electrolyte | Ag-enhanced interface | cathode. This method uses a calcination temperature higher than the melting point of Ag (~962 °C) to melt the Ag particles in the cathode and settle them to the cathode / electrolyte interface, and partially coat the connection between the cathode and the electrolyte, thereby constructing an Ag-enhanced interface that can improve the combination of the two. The Ag-enhanced interface can effectively improve the problem of weak bonding at the SOFC cathode / electrolyte interface, increase the effective contact area of the interface, and simultaneously enhance the ORR activity and conductivity of the cathode, thereby significantly improving the electrochemical performance and durability of the battery.

[0010] Specifically, in step S2, first mix and grind the cathode material and silver powder to obtain a "cathode + Ag" composite powder; the Ag content in the "cathode + Ag" composite powder is 5 - 40 wt.%; then weigh the corresponding raw materials according to the mass ratio of "cathode + Ag" composite powder: ethyl cellulose: terpineol = 10: 0.3 - 1: 10, mix and grind to obtain a "cathode + Ag" composite slurry.

[0011] Specifically, the thickness of the cathode layer obtained in S4 can be 2 - 50 μm.

[0012] The present invention provides an SOFC prepared by the above preparation method.

[0013] The present invention ingeniously utilizes the melting of cathode Ag particles to construct an Ag-enhanced interface and improve the combination of the SOFC cathode and electrolyte. This method can effectively increase the actual contact area of the cathode / electrolyte interface and significantly improve the electrochemical performance and durability of the battery.

[0014] Compared with the prior art, the method for improving the combination of the SOFC cathode and electrolyte by the Ag-enhanced interface in the present invention has the following advantages and beneficial effects: 1) Compared with the reported metal intermediate functional layers with a grid structure having a large spacing (50 - 400 μm), the Ag particle size of the Ag-enhanced interface in the present invention is only in the micron scale (<5 μm) or even in the sub-micron scale (100 nm - 1 μm), which is consistent with the cathode particle size. This size structure ensures that the Ag-enhanced interface in the present invention has a significant and effective enhancement effect on both the macroscopic interface and the local microscopic structure of the cathode / electrolyte.

[0015] 2) The present invention ingeniously utilizes the melting and sedimentation of Ag particles in the cathode to construct an Ag-enhanced interface. This method belongs to the conventional SOFC preparation process and can be achieved synchronously during the normal preparation process of the battery; no additional and complex preparation processes and procedures are required; the process is simple and easy to control, suitable for large-scale production.

[0016] 3) The TEC value of Ag is between that of the cathode and the electrolyte material, which can effectively buffer the interfacial thermal stress; in addition, Ag has good ductility and deformation ability, which can effectively connect the cathode and the electrolyte, relieve the interfacial deformation, cracking, etc. caused by stress and other factors, and improve the electrochemical performance and durability of the battery.

[0017] 4) In addition to the role of improving the cathode / electrolyte interface bonding, Ag itself also has excellent ORR activity and conductivity, which can effectively enhance the ORR ability and electron transport ability of the cathode, and synergistically improve the performance of SOFC. Brief Description of the Drawings

[0018] Figure 1 XRD patterns of the "Ag + cathode" (a, b) and "Ag + electrolyte" (c, d) mixed powders prepared in Example 1 of the present invention after calcination at 1000 °C, where Figures (b) and (d) are the partial enlarged views of Figures (a) and (c), respectively; Figure 2 XPS spectra of the "Ag + cathode" mixed powder prepared in Example 1 of the present invention before (a, b) and after (c, d) calcination at 1000 °C; Figure 3 SEM + EDS stratification diagrams (a) of a partial cross-section of a single cell with the structure of anode|electrolyte|cathode + Ag|cathode and the corresponding SEM (b) and EDS (c) diagrams prepared in Example 1 of the present invention after calcination at 950 °C, used to observe the distribution of Ag in the battery structure before melting; Figure 4 SEM and EDS diagrams of a partial cross-section of a single cell with the structure of anode|electrolyte|Ag-enhanced interface|cathode prepared in the present invention with Ag contents of 0 (a), 10 (b), 20 (c), and 30 (d) wt.% after calcination at 1000 °C; Figure 5 Results of the cathode / electrolyte interface peeling test of single cells with the structure of anode|electrolyte|Ag-enhanced interface|cathode with different Ag contents prepared in the present invention; Figure 6 I-V and I-P curves of single cells with Ag contents of 0 (a) and 20 (b) wt.% prepared in the present invention, and the corresponding long-term stability (c) and thermal cycle stability (d) test results; Figure 7EIS curves (a) of single cells with Ag contents of 0 and 20 wt.% prepared according to the present invention, and the corresponding ohmic resistance R o (b), polarization resistance R p (c) Arrhenius plot; Figure 8 Process for improving the bonding between the cathode and electrolyte of SOFC based on Ag-enhanced interface according to the present invention. Detailed implementation manners

[0019] The technical solutions of the present invention will be further introduced in detail below in conjunction with embodiments, but the protection scope of the present invention is not limited thereto. In order to enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be further described below in conjunction with specific embodiments, but the embodiments cited are not intended to limit the present invention. Unless otherwise defined, all professional terms used hereinafter have the same meaning as commonly understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the protection scope of the present invention.

[0020] Unless otherwise specifically stated, various raw materials, reagents, instruments and equipment used in the following embodiments of the present invention can be obtained through market purchase or prepared by existing methods.

[0021] In the following embodiments, the Ag raw material for preparing the "cathode + Ag" layer is silver powder, and the silver powder is commercial silver powder with a particle size of 50 nm - 2 μm.

[0022] Example 1 A method for improving the bonding between the cathode and electrolyte of SOFC based on Ag-enhanced interface, which additionally adds a "cathode + Ag" layer between the cathode and electrolyte layers. The thickness of the "cathode + Ag" layer is 5 μm. The Ag content in the "cathode + Ag" layer is 20 wt.%.

[0023] A method for preparing an SOFC with an Ag-enhanced interface (for the specific process, see Figure 8 ), which includes the following steps: S1: Prepare the cathode material and the corresponding cathode slurry; a. Weigh the BSF prepared by the sol-gel method and the NM powder prepared by the solid-phase reaction method according to the mass ratio, and mix them evenly by ball milling to obtain the BSF-20NM composite cathode material; b. Further weigh the BSF-20NM composite cathode material, ethyl cellulose, and terpineol according to the mass ratio, and mix and grind them to obtain the cathode slurry; S2: Use the cathode material obtained in S1 and silver powder to prepare a "cathode + Ag" composite slurry; a. Weigh the obtained BSF-20NM composite cathode material and silver powder in step S1 according to the corresponding ratio, and mix and grind them for 2 h to obtain the "cathode + Ag" composite powder. The Ag content in the "cathode + Ag" composite powder is 20 wt.%. b. Weigh the corresponding raw materials according to the mass ratio of the obtained "cathode + Ag" composite powder: ethyl cellulose: terpineol = 10:1:10, and mix and grind them for 3 h to obtain the "cathode + Ag" composite slurry. S3: Prepare the anode|electrolyte configuration SOFC half-cell, that is, the NiO-SDC|SDC half-cell. The heat treatment temperature is 1450 °C and the heat treatment time is 5 h. The preparation process of the NiO-SDC|SDC half-cell can be specifically referred to the method in the existing literature (Kang Liu, Fei Lu, et al. A high performance thermal expansion offset composite cathode for IT-SOFCs†. Journal of Materials Chemistry A, 2022, 10, 24410). S4: Coat a layer of the "cathode + Ag" composite slurry obtained in S2 on the SDC surface of the half-cell obtained in S3, and dry it. The thickness of the obtained "cathode + Ag" layer is 5 μm. S5: Continuously coat a layer of the cathode slurry obtained in S1 on the basis of S4, and dry it. The thickness of the obtained cathode layer is 10 μm. S6: Calcinate the half-cell obtained in S5 at 1000 °C for 3 h to obtain the SOFC single cell with the structure of anode|electrolyte|Ag enhanced interface|cathode.

[0024] In addition, in order to observe the distribution of Ag in the cell structure before melting, this example additionally prepared an SOFC single cell with the structure of anode|electrolyte|Ag enhanced interface|cathode obtained by calcining at 950 °C for 3 h in step S6 for comparison.

[0025] The above-mentioned electrolyte is the classical oxygen ion conductor electrolyte Ce 0.8 Sm 0.2 O 2-δ (SDC); the cathode material used is the thermal expansion compensation composite cathode material Ba 0.5 Sr 0.5 FeO 3-δ -20NdMnO 3-δ(BSF-20NM). Specific preparation details of the cathode material and cathode slurry can be referred to relevant literature (Lu F, Shi Y, Shi L, et al. Improved SOFC performance by enhancing cathode / electrolyte bonding and grain refinement of cathode with thermal expansion offset[J]. Ceramics International, 2024, 50(22): 46318-46326.) and patents (Cai Bin, Lu Fei, Yang Mengjie, et al. A novel composite cathode material containing negative thermal expansion material and its application in preparing SOFC [P]. Chinese invention patent, CN111403754B).

[0026] Example 2 A method for improving the bonding between the cathode and electrolyte of SOFC based on Ag-enhanced interface, which additionally adds a "cathode + Ag" layer between the cathode and electrolyte layers. The thickness of the "cathode + Ag" layer is 5 μm. The Ag content in the "cathode + Ag" layer is 10 wt.%.

[0027] The preparation process of the SOFC single cell with the structure of anode|electrolyte|Ag-enhanced interface|cathode refers to Example 1.

[0028] Example 3 A method for improving the bonding between the cathode and electrolyte of SOFC based on Ag-enhanced interface, which additionally adds a "cathode + Ag" layer between the cathode and electrolyte layers. The thickness of the "cathode + Ag" layer is 5 μm. The Ag content in the "cathode + Ag" layer is 30 wt.%.

[0029] The preparation process of the SOFC single cell with the structure of anode|electrolyte|Ag-enhanced interface|cathode refers to Example 1.

[0030] Example 4 A method for improving the bonding between the cathode and electrolyte of SOFC based on Ag-enhanced interface, which additionally adds a "cathode + Ag" layer between the cathode and electrolyte layers. The thickness of the "cathode + Ag" layer is 5 μm. The Ag content in the "cathode + Ag" layer is 40 wt.%.

[0031] The preparation process of the SOFC single cell with the structure of anode|electrolyte|Ag-enhanced interface|cathode refers to Example 1.

[0032] Comparative Example 1 A method for improving the bonding between the cathode and electrolyte of a SOFC based on Ag-enhanced interface, which additionally adds a "cathode + Ag" layer between the cathode and electrolyte layers. The thickness of the "cathode + Ag" layer is 5 μm. The Ag content in the "cathode + Ag" layer is 0 wt.%.

[0033] The preparation process of the SOFC single cell with the anode|electrolyte|Ag-enhanced interface|cathode refers to Example 1.

[0034] Figure 1 XRD patterns of the "Ag + cathode" (a, b) and "Ag + electrolyte" (c, d) mixed powders prepared in Example 1 of the present invention after calcination at 1000 °C, where Figures (b) and (d) are the partial enlarged views of Figures (a) and (c) respectively. It can be seen from the figure that no diffraction peaks related to the second phase or impurity phase were observed after the mixed calcination of the "Ag + cathode (i.e., BSF-NM-Ag)" and "Ag + electrolyte (i.e., SDC-Ag)" mixed powders. The peak position shifts in the partial enlarged views shown in Figures (b) and (d) are also very small. This indicates good chemical compatibility between BSF, NM, SDC, and Ag.

[0035] Figure 2 XPS spectra of the "Ag + cathode" mixed powder prepared in Example 1 of the present invention before (a, b) and after (c, d) calcination at 1000 °C. It can be seen from the figure that there is no obvious binding energy shift in the peaks of Fe and Ag elements before and after the mixed calcination, further proving the good compatibility between Ag, BSF, and NM.

[0036] Figure 3 SEM + EDS layer-by-layer diagram (a) of a partial cross-section of a single cell with the structure of anode|electrolyte|cathode + Ag|cathode prepared additionally in Example 1 of the present invention after calcination at 950 °C, and the corresponding SEM (b) and EDS (c) diagrams, used to observe the distribution of Ag in the cell structure before melting. It can be seen from the figure that Ag particles are relatively evenly distributed in the "cathode + Ag" layer, and the thickness of the "cathode + Ag" layer is about 5 μm, which is basically consistent with the designed thickness and meets the use requirements.

[0037] Figure 4SEM and EDS images of a partial cross-section of a single cell with the structure of anode|electrolyte|Ag-enhanced interface|cathode after calcination at 1000 °C when the Ag content prepared according to the present invention is 0 (a), 10 (b), 20 (c), and 30 (d) wt.%. It can be seen from the figure that since the melting point of Ag is 960 °C and the single cell is calcined at 1000 °C, the Ag in the "cathode + Ag" layer will melt and settle to the cathode / electrolyte interface, and partially coat the connection between the cathode and the electrolyte, forming an "Ag-enhanced interface", which plays a role in connecting the cathode and the electrolyte. When the Ag content increases from 10 wt.% to 20 wt.%, 30 wt.%, the Ag at the Ag-enhanced interface also increases significantly after sintering at 1000 °C, forming dot-like, island-like, and flake-like structures respectively; the increase in Ag at the Ag-enhanced interface is beneficial to enhancing the cathode / electrolyte bonding, but too much Ag is not conducive to gas diffusion.

[0038] Figure 5 Results of the cathode / electrolyte interface peeling test of single cells with the structure of anode|electrolyte|Ag-enhanced interface|cathode and different Ag contents (0, 10, 20, 30 wt.%) prepared according to the present invention. It can be seen from the figure that as the Ag content increases, the cathode / electrolyte interface peeling strength also continuously increases; the cathode / electrolyte interface peeling strength when the Ag content is 20 wt.% is 11.3 N·cm -2 , compared with 0 wt.% (6.1 N·cm -2 ) it is increased by about 85.3%. This result quantitatively proves the good connection effect of the Ag-enhanced interface and can significantly improve the cathode / electrolyte interface bonding.

[0039] Figure 6 I-V and I-P curves of single cells with Ag contents of 0 (a) and 20 (b) wt.% prepared in Comparative Example 1 and Example 1 of the present invention, and the corresponding long-term stability (c) and thermal cycle stability (d) test results. It can be seen from (a) and (b) in the figure that at 450 - 650 °C, compared with the single cell with 0 wt.% Ag content, the PPD of the single cell with 20 wt.% Ag content increases from 161 - 1511 mW∙cm -2 to 185 - 1653 mW∙cm -2 , quantitatively proving that the construction of the Ag-enhanced interface can effectively improve the output performance of SOFC single cells. It can be seen from (c, d) in the figure that compared with the single cell with 0 wt.% Ag content, the performance decay rates of the single cell with 20 wt.% Ag content after long-term operation and thermal cycle operation are reduced from 14.7% and 15.7% to 10.9% and 8.3% respectively, proving that while the Ag-enhanced interface improves the output performance of SOFC single cells, it can also effectively improve its long-term stability and thermal cycle stability.

[0040] Figure 7 EIS curves (a) and corresponding ohmic resistance R of single cells with Ag contents of 0 and 20 wt.% prepared in Comparative Example 1 and Example 1 of the present invention o (b), polarization resistance R p (c) Arrhenius plots. It can be seen from the figure that at 450 - 650 °C, compared with the single cell with 0 wt.% Ag content, the ohmic and polarization resistances of the single cell with 20 wt.% Ag content are significantly reduced; indicating that the construction of the Ag-enhanced interface can effectively reduce the resistance, thereby improving the cell performance.

[0041] Figure 8 Process flow of the method for improving the bonding between the cathode and electrolyte of SOFC based on the Ag-enhanced interface in the present invention. It can be seen that the method used in the present invention belongs to the conventional SOFC preparation process and can be realized synchronously during the normal preparation process of the cell; no additional and complex preparation processes and procedures are required; the process is simple and easy to control, and is suitable for large-scale production.

Claims

1. A method for improving the bonding between SOFC cathode and electrolyte based on Ag enhanced interface, characterized in that: An additional "cathode + Ag" layer is added between the cathode and electrolyte layers.

2. The method according to claim 1, characterized in that The thickness of the "cathode + Ag" layer is 2-10 μm.

3. The method according to claim 1 or 2, characterized in that The Ag content in the "cathode+Ag" layer is 5-40 wt.%.

4. The method according to claim 1, characterized in that The Ag raw material used to prepare the "cathode + Ag" layer is silver powder.

5. The method according to claim 4, characterized in that The particle size of the silver powder is 50 nm-2 μm.

6. A method for preparing a SOFC containing an Ag enhanced interface, characterized in that: The steps include: S1: preparing cathode material and corresponding cathode slurry; S2: Prepare a "cathode + Ag" composite slurry by mixing the cathode material obtained in S1 with silver powder; S3: Apply a layer of "cathode + Ag" composite slurry obtained in S2 on the surface of the SOFC half-cell electrolyte and dry it; S4: Continue to apply a layer of cathode slurry obtained in S1 on the basis of S3, and dry; S5: Calcine the half-cell obtained in S4 at 980-1200 °C for 1-5 h.

7. The preparation method according to claim 6, characterized in that: In step S2, the cathode material and silver powder are first mixed and ground to obtain a "cathode + Ag" composite powder; the Ag content in the "cathode + Ag" composite powder is 5-40 wt.%; then the corresponding raw materials are weighed according to the mass ratio of "cathode + Ag" composite powder: ethyl cellulose: pinene alcohol = 10:0.3-1:10, mixed and ground to obtain a "cathode + Ag" composite slurry.

8. The preparation method according to claim 6, characterized in that: The cathode layer thickness obtained by S4 was 2-50 μm.

9. SOFC prepared by the preparation method according to any one of claims 6 to 8.

Images