Electrochemical device pipeline connecting assembly and application thereof

Abstract

The invention relates to the technical field of electrochemical device pipeline connection, and provides an electrochemical device pipeline connection assembly and application thereof, and by adopting the electrochemical device pipeline connection assembly, the requirements of gas transmission, sealing and insulation between a cell stack and an external metal pipeline at high temperature can be met at the same time. The pipeline connecting assembly comprises a connecting piece for communicating an external first metal pipeline with a second metal pipeline which is in electric contact with the electrochemical device; the connecting piece comprises a first sealing washer, a ceramic communicating pipeline and a second sealing washer which are sequentially arranged between the first metal pipeline and the second metal pipeline; the thermal expansion coefficient of the connecting piece is between the thermal expansion coefficient of the first metal pipeline and the thermal expansion coefficient of the second metal pipeline.

Description

Technical Field

[0001] This invention relates to the field of pipeline connection technology for electrochemical devices, and further to pipeline connection technology for solid oxide fuel cells, specifically to a pipeline connection component for electrochemical devices and its application. Background Technology

[0002] Solid oxide fuel cells (SOFCs) are all-solid-state chemical power generation devices that directly convert the chemical energy in fuel into electrical energy. They operate at temperatures of 600-1000℃ and have advantages such as high power generation efficiency, wide fuel adaptability, strong resistance to degradation, and low environmental pollution.

[0003] To meet the gas transport requirements of SOFC battery stacks at high temperatures, external metal pipes are needed to connect to the inlet and outlet pipes of the anode and cathode of the battery stack to transport the anode and cathode gases. During operation, the anode and cathode inlets and outlets of the battery stack are typically electrically connected to the power take-up plate. If these connections are not insulated from the external metal pipes, current will be conducted through the metal pipes to the grounding auxiliary system or other battery stacks, posing a risk of short circuits or electric shock.

[0004] CN211550833U, CN113611904A, and CN117267490A all employ two sealing flanges with an insulating layer in between, such as insulating ceramic sheets, mica gaskets, or other insulating materials. The bolts or screws used to fasten the flanges are equipped with ceramic collars to achieve insulation between the fuel cell stack and the external metal pipe flanges, respectively. This design has multiple insulation interfaces, especially the collar method used for insulation between the bolts and the flanges, which poses potential risks such as insufficient ceramic ring thickness or cracking during installation and operation, reducing insulation reliability. In addition, the flange-connected gas pipes all need to be welded to the external metal pipes, making maintenance and replacement inconvenient. Summary of the Invention

[0005] To address at least one deficiency in existing technologies, this invention provides an electrochemical device pipeline connection assembly and its application. When used in electrochemical devices, particularly solid oxide fuel cell power generation devices, the electrochemical device pipeline connection assembly of this invention can simultaneously meet the gas transmission, sealing, and insulation requirements between the battery stack and external metal pipelines at high temperatures. Moreover, it can effectively reduce the risk of gas leakage in high-temperature application scenarios and has high sealing and insulation reliability.

[0006] To achieve its objective, the present invention provides the following technical solution:

[0007] This invention provides an electrochemical device pipeline connection assembly, the pipeline connection assembly including a connector for connecting an external first metal pipe and a second metal pipe that is in electrical contact with the electrochemical device;

[0008] The connector includes a first sealing gasket, a ceramic connecting pipe, and a second sealing gasket, which are sequentially disposed between the first metal pipe and the second metal pipe; when the connector is connected between the first metal pipe and the second metal pipe, the ceramic connecting pipe can communicate with the first metal pipe and the second metal pipe.

[0009] The coefficient of thermal expansion of the connector is between that of the first metal pipe and the second metal pipe.

[0010] Furthermore, the absolute value of the difference between the coefficient of thermal expansion of the connector and the coefficients of thermal expansion of the first metal pipe and the second metal pipe is less than 3.5 × 10⁻⁶. -6 K -1 .

[0011] In another aspect, the present invention provides an electrochemical device pipeline connection mechanism, the pipeline connection mechanism comprising an external first metal pipeline, a second metal pipeline in electrical contact with the electrochemical device, and a pipeline connection assembly connecting the first metal pipeline and the second metal pipeline.

[0012] The pipe connection assembly is the pipe connection assembly described above.

[0013] In another aspect, the present invention also provides the application of the electrochemical device pipeline connection assembly described above in an electrochemical device, preferably, the electrochemical device being a solid oxide fuel cell.

[0014] The technical solution provided by this invention has the following beneficial effects:

[0015] The electrochemical device piping connection assembly provided by this invention can simultaneously meet the gas transmission, sealing, and insulation requirements between the battery stack and the external metal piping at high temperatures, ensuring the stable operation of the fuel cell power generation device. In the piping connection assembly of this invention, the thermal expansion coefficient of the connector is controlled between that of the first metal piping and the second metal piping, and the absolute value of the difference is controlled to be less than 3.5 × 10⁻⁶. -6 K -1 The provided connection components can reduce the total amount of high-temperature expansion deformation of gas transmission pipelines, reduce thermal stress, enhance structural stability, effectively avoid gas leakage caused by excessive deformation differences, and improve the reliability of system insulation and sealing. Attached Figure Description

[0016] Figure 1 This is a three-dimensional structural diagram of an electrochemical device pipeline connection assembly connected between first and second metal pipelines 1 and 2 in one embodiment.

[0017] Figure 2 for Figure 1 A schematic diagram of the decomposed structure;

[0018] Figure 3 for Figure 1 Front view diagram;

[0019] Figure 4 for Figure 1 A cross-sectional schematic diagram;

[0020] Figure 5 This is a schematic diagram of the flange plate structure of a split flange in one embodiment. Detailed Implementation

[0021] To facilitate understanding of the present invention, the following description, in conjunction with embodiments, will further illustrate the invention. It should be understood that the following embodiments are merely for a better understanding of the invention and do not imply that the invention is limited to these embodiments.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The term "and / or" may be used herein to include any and all combinations of one or more of the associated listed items.

[0023] The directional terms such as up, down, left, right, front, back, front, back, top, and bottom mentioned or possibly used in this specification are defined relative to the structures shown in the accompanying drawings. These are relative concepts and may therefore vary depending on their location and usage. The terms "inner" and "outer" refer to directions toward or away from the geometric center of a specific component, respectively. Furthermore, the terms "first," "second," and "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. In the description of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly; for example, they may refer to direct connection or indirect connection through an intermediate medium. Those skilled in the art can understand the specific meanings of the above terms within the context of this application, depending on the specific circumstances.

[0024] This invention provides a pipe connection assembly for an electrochemical device. The assembly includes a connector for connecting an external first metal pipe 1 and a second metal pipe 2 that is in electrical contact with the electrochemical device. The second metal pipe 2 is in electrical contact with the battery stack, and the first metal pipe 1 is an external metal pipe. The pipe connection assembly provides this invention for connecting the first and second metal pipes 1 and 2. The connector is connected between the first metal pipe 1 and the second metal pipe 2. Specifically, the connector includes a ceramic connecting pipe 3, a first sealing gasket 6, and a second sealing gasket 7. When the connector is connected between the first and second metal pipes 1 and 2, the first sealing gasket 6, the ceramic connecting pipe 3, and the second sealing gasket 7 are arranged sequentially along the direction from the first metal pipe 1 to the second metal pipe 2, and the ceramic connecting pipe 3 is connected to both the first metal pipe 1 and the second metal pipe 2. The first sealing gasket 6 is located between the first metal pipe 1 and the ceramic connecting pipe 3, i.e., at the connection point of the first metal pipe 1 and the ceramic connecting pipe 3, and serves a sealing function. The second sealing gasket 7 is disposed between the second metal pipe 2 and the ceramic connecting pipe 3, that is, at the connection between the second metal pipe 2 and the ceramic connecting pipe 3, and serves a sealing function. The coefficient of thermal expansion of the connector is between the coefficient of thermal expansion of the first metal pipe 1 and the coefficient of thermal expansion of the second metal pipe 2; and the absolute value of the difference between the coefficient of thermal expansion of the connector and the coefficients of thermal expansion of the first and second metal pipes is less than 3.5 × 10⁻⁶. -6 K -1 That is, the absolute value of the difference between the thermal expansion coefficient of the connector and the thermal expansion coefficient of the first metal pipe 1 is less than 3.5 × 10⁻⁶. -6 K -1 And the absolute value of the difference between the thermal expansion coefficient of the connector and the thermal expansion coefficient of the second metal pipe 2 is less than 3.5 × 10⁻⁶. -6 K -1 .

[0025] The electrochemical device piping connection assembly provided by this invention can simultaneously meet the gas transmission, sealing, and insulation requirements between the battery stack and the external metal piping at high temperatures, ensuring the stable operation of the fuel cell power generation device. In the piping connection assembly of this invention, the thermal expansion coefficient of the connector is controlled between the thermal expansion coefficients of the first metal pipe 1 and the second metal pipe 2, and the absolute value of the difference is controlled to be less than 3.5 × 10⁻⁶. -6 K -1 This can reduce the total amount of high-temperature expansion deformation of gas transmission pipelines, reduce high-temperature stress, enhance structural stability, effectively avoid stretching or compression due to large differences in high-temperature expansion deformation between the first and second metal pipelines 1 and 2, and avoid gas leakage caused by excessive differences in deformation.

[0026] Furthermore, the pipe connection assembly also includes a first metal fastener 4 and a second metal fastener 5, such as a clamp or flange. The first metal fastener 4 is used to securely connect the connector to the first metal pipe 1; the second metal fastener 5 is used to securely connect the connector to the second metal pipe 2. Preferably, the material of the first metal fastener 4 is the same as that of the first metal pipe 1, or the absolute value of the difference between the coefficient of thermal expansion of the first metal fastener 4 and the coefficient of thermal expansion of the first metal pipe 1 is less than 1.5 × 10⁻⁶. -6 K -1 The material of the second metal fastener 5 is the same as that of the second metal pipe 2, or the absolute value of the difference between the coefficient of thermal expansion of the second metal fastener 5 and the coefficient of thermal expansion of the second metal pipe 2 is less than 1.5 × 10⁻⁶. -6 K -1 Through this preferred method, when the materials of the first metal pipe 1 and the second metal pipe 2 are different, corresponding metal fasteners with the same material as the corresponding metal pipe or with similar coefficients of thermal expansion can be used to improve the sealing performance of the pipe connection.

[0027] In the text, the "coefficient of thermal expansion" in the phrases "difference between the thermal expansion coefficient of the connector and the first metal pipe", "difference between the thermal expansion coefficient of the connector and the second metal pipe", "difference between the thermal expansion coefficient of the first metal fastener and the first metal pipe", and "difference between the thermal expansion coefficient of the second metal fastener and the second metal pipe" all refer to the average thermal expansion coefficient within the range of 20-800℃.

[0028] In some application examples, one end of the first metal pipe 1 in the electrochemical device is provided with a first flange 11, and one end of the second metal pipe 2 is provided with a second flange 21. For such first and second metal pipes 1 and 2, in a preferred embodiment of the present invention, the two ends of the ceramic connecting pipe 3 are respectively provided with a first flange 31 and a second flange 32. When the connector is connected between the first and second metal pipes 1 and 2, a first sealing gasket 6 is sandwiched between the first flange 31 and the first flange 11, and a second sealing gasket 7 is sandwiched between the second flange 32 and the second flange 21. Specifically, the first sealing gasket 6 and the second sealing gasket 7 can each be an O-ring. Preferably, the first sealing gasket 6 and the second sealing gasket 7 are compressible sealing gaskets, with a compression ratio preferably of 20-40%. The surface of the first flange 31 that contacts the first sealing gasket 6 is provided with a groove (not shown in the figure, see groove 33), preferably an annular groove, for example, multiple annular grooves; the surface of the second flange 32 that contacts the second sealing gasket 7 is provided with a groove 33, preferably an annular groove, for example, multiple annular grooves. The compressible sealing gaskets are compressible. When the connector is compressed due to high-temperature expansion, the first and second sealing gaskets 6 and 7 can elastically deform and fill the grooves opened on the first flange 31 and second flange 32 of the ceramic connecting pipe 3, thereby effectively compensating for the deformation and displacement of the first and second metal pipes 1 and 2 and the connector caused by thermal expansion, ensuring the sealing and stability of the connection. More specifically, the first flange 31 and the second flange 32 are L-shaped flanges.

[0029] In a preferred embodiment, the first metal fastener 4 is a first split flange 41 adapted to the first flange 11, and the second metal fastener 5 is a second split flange 51 adapted to the second flange 21. Specifically, the first split flange 41 and the second split flange 51 are respectively assembled from multiple flange plates 43 and 56, forming a first split flange 41 and a second split flange 51 that can be fitted onto the ceramic connecting pipe 3; specifically, the multiple flange plates 43 and 56 are respectively assembled to form a ring-shaped first split flange 41 and a second split flange 51. When the ceramic connecting pipe 3 is fastened to the first flange 11 via the first split flange 41, the first split flange 41 is fitted onto the first flange 31 of the ceramic connecting pipe 3; when the ceramic connecting pipe 3 is fastened to the second flange 21 via the second split flange 51, the second split flange 51 is fitted onto the second flange 32 of the ceramic connecting pipe 3. Preferably, the first split flange 41 is provided with a first limiting groove 42 for accommodating the first flange 31 and the first sealing gasket 6. When the ceramic connecting pipe 3 and the first flange 11 are fastened together by the first split flange 41, the first flange 31 and the first sealing gasket 6 of the ceramic connecting pipe 3 are both located in the first limiting groove 42, and the first flange 31 abuts against the first split flange 41 through the first limiting groove 42. The first flange 31 and the first limiting groove 42 of the first split flange 41 cooperate to play the role of positioning and limiting. Preferably, the second split flange 51 is provided with a second limiting groove 53 for accommodating the second flange 32 and the second sealing gasket 7. When the ceramic connecting pipe 3 and the second flange 21 are fastened together by the second split flange 51, the second flange 32 and the second sealing gasket 7 of the ceramic connecting pipe 3 are both located in the second limiting groove 53, and the second flange 32 abuts against the second split flange 51 through the second limiting groove 53. The second flange 32 and the second limiting groove 53 of the second split flange 51 cooperate to play the role of positioning and limiting.

[0030] In the preferred embodiment, see Figure 2 , Figure 5 The first split flange 41 has flange plates 43 with splicing structures formed on each flange plate 43, enabling them to be spliced ​​together to form the first split flange 41; the second split flange 51 has flange plates 56 with splicing structures formed on each flange plate 56, enabling them to be spliced ​​together to form the second split flange 51. Preferably, the splicing structure includes mutually adaptable positioning grooves and positioning protrusions. Taking the flange plate 56 of the second split flange 51 as an example, see... Figure 5For example, positioning grooves 55 and positioning protrusions 54 are formed on each flange plate 56; or, positioning grooves 55 are formed on some flange plates 56 and positioning protrusions 54 are formed on some flange plates 56; when splicing the flange plates 56, the splicing is achieved by the insertion of the positioning grooves 55 and positioning protrusions 54 that are mutually adapted between the flange plates 56; the specific description of the splicing structure of the flange plate 43 of the first split flange 41 can be referred to the description of the flange plate 56, and will not be repeated here.

[0031] More specifically, the first split flange 41 has a connection structure for bolting to the first flange 11, and the second split flange 51 has a connection structure for bolting to the second flange 21. For example, the first flange 11 and the first split flange 41 are respectively provided with through holes 12 and 44. By inserting the screw 81 into the through holes 12 and 44 of the first flange 11 and the first split flange 41, and tightening the nuts 82 at both ends of the screw 81, the clamping force of the screw 81 and the nuts 82 is used to achieve a tight connection. At the same time, the compressible first sealing gasket 6 undergoes elastic deformation, improving the sealing performance. The bolting connection between the second flange 21 and the second split flange 51 is similar and will not be described in detail.

[0032] In a preferred embodiment of the present invention, the first metal fastener 4 and the second metal fastener 5 are respectively a first split flange 41 and a second split flange 51 that are easy to install and disassemble. The metal fasteners can be reused, and there is no need to perform special treatment on the first and second metal pipes 1 and 2 to be connected and the corresponding first and second flanges 11 and 21. Furthermore, there is no need for on-site cutting and welding, which can effectively reduce construction costs.

[0033] In a preferred embodiment, the ceramic connecting pipe 3 has an average coefficient of thermal expansion of (10-13)×10⁻⁶ in the temperature range of 20-800℃. -6 K -1 The flexural strength is 50-200MPa, and the electrical resistance is (5-10)×10⁻⁶. 13Ω. Using a ceramic connecting pipe 3 with this preferred performance characteristic helps to obtain the required connector with the required coefficient of thermal expansion. On the other hand, using such a ceramic connecting pipe 3 as a gas channel, after being connected to the metal pipe with metal fasteners, can ensure that the battery stack inlet and outlet pipes are in an insulated state from the external first metal pipe 1, eliminating the risk of short circuit between the battery stack and the external metal pipe, which is beneficial to ensuring the safety of the fuel cell. Preferably, the ceramic connecting pipe 3 contains 10-30 wt% diopside, 25-60 wt% magnesium oxide, 15-40 wt% forsterite, and 1-8 wt% aluminum nitride; more preferably, the ceramic connecting pipe 3 contains 15-25 wt% diopside, 35-50 wt% magnesium oxide, 20-35 wt% forsterite, and 3-5 wt% aluminum nitride. The inventors have found that the ceramic connecting pipe 3 using the above-mentioned formulation can better control the coefficient of thermal expansion and resistance, and has an average coefficient of thermal expansion, bending strength, and resistance value within the range of 20-800℃ that meets the above requirements. Using such a ceramic connecting pipe 3 helps to obtain connectors with the required coefficient of thermal expansion and can effectively eliminate the risk of short circuit between the battery stack and the external metal pipe, thereby improving safety.

[0034] The ceramic connecting pipe 3 can be prepared using conventional manufacturing techniques in the art. For example, in some embodiments, the preparation method of the ceramic connecting pipe 3 includes the following preparation steps:

[0035] (1a) The ceramic powder and binder are mixed evenly, and the mixture is kneaded to obtain a mixed clay material, for example, in a kneading machine; wherein the ceramic powder comprises 10-30 wt% diopside, 25-60 wt% magnesium oxide, 15-40 wt% forsterite and 1-8 wt% aluminum nitride; more preferably, the ceramic powder comprises 15-25 wt% diopside, 35-50 wt% magnesium oxide, 20-35 wt% forsterite and 3-5 wt% aluminum nitride;

[0036] (2a) The mixed clay is kneaded, for example, in a vacuum kneading machine, and kneading can be performed multiple times under different vacuum degrees; then it is sealed and aged, for example, for 12-24 hours; the resulting clay is shaped to obtain a ceramic connecting pipe blank; the blank is dried and sintered, and the sintered sample is mechanically treated, including one or more of cutting, grinding, and polishing, to obtain the ceramic connecting pipe 3. Specifically, the kneading can be performed multiple times as needed, for example, multiple kneadings under different vacuum degrees, and after each kneading, it is sealed and aged for a period of time, for example, 12-24 hours.

[0037] Using the above preparation method, an average thermal expansion coefficient of (10-13)×10⁻⁶ can be obtained at temperatures ranging from 20 to 800℃. -6K -1 The flexural strength is 50-200MPa, and the electrical resistance is (5-10)×10⁻⁶. 13 The ceramic connecting pipe 3 of Ω; In the pipe connection assembly of the present invention, the ceramic connecting pipe 3 obtained by the above preparation method is easy to obtain the connector with the required thermal expansion coefficient, and can effectively eliminate the short circuit risk between the battery stack and the external metal pipe, thereby improving safety.

[0038] Preferably, in step (1a), the binder is one or more of dextrin, polyvinyl alcohol, polyacrylic acid, and cellulose, with cellulose being preferred; preferably, the amount of binder used is 5-30 wt% of the amount of ceramic powder.

[0039] Preferably, in step (1a), when kneading the clay, a mixed solvent of ethanol and water is added, preferably the mass percentage of ethanol in the mixed solvent is 40-60%, and the amount of the mixed solvent is 10-20 wt% of the amount of ceramic powder.

[0040] Preferably, in step (1a), during the kneading process, after adding the mixed solvent of ethanol and water for kneading, an extrusion aid and an ethanol solvent are added to continue kneading. The extrusion aid is, for example, one or more of emulsified silicone oil, aluminum stearate, and graphite, preferably emulsified silicone oil; preferably, the amount of the extrusion aid is 5-15 wt% of the ceramic powder. Specifically, for example, after the ceramic powder and binder are mixed evenly in a kneader, they are added to the kneader together with the mixed solvent of ethanol and water, and kneaded for 30-60 minutes; then, the extrusion aid and the ethanol solvent are added, and kneading continues for 15-30 minutes to obtain a mixed clay. The amount of the ethanol solvent is, for example, 2-8 wt% of the ceramic powder.

[0041] In step (2a), the molding process can be selected from one of dry pressing, isostatic pressing, extrusion molding, slip casting, hot die casting, injection molding and injection molding, preferably dry pressing or injection molding.

[0042] Specifically, in step (2a), the drying process may involve naturally drying the ceramic connecting pipe blank at room temperature, for example, for 12-24 hours; followed by further drying, for example, at a drying temperature of 80-120°C for 5-12 hours, which may be achieved using programmed temperature control. Preferably, the sintering process includes: first holding at 200-400°C for 2-10 hours to remove the binder and extrusion aid, and then raising the temperature to 1400-1600°C and holding for 2-5 hours. For example, during the sintering process, the temperature may be raised to 200-400°C at a rate of 3°C / min and then raised to 1400-1600°C at a rate of 5°C / min.

[0043] In a preferred embodiment, the coefficient of thermal expansion of the first sealing gasket 6 and the second sealing gasket 7 are respectively located between the coefficients of thermal expansion of the first metal pipe 1 and the second metal pipe 2. This helps to obtain the required coefficient of thermal expansion for the connector and further improves the sealing reliability of the connection assembly. The coefficient of thermal expansion refers to the average coefficient of thermal expansion in the range of 20-800℃.

[0044] Preferably, the average coefficients of thermal expansion of the first sealing gasket 6 and the second sealing gasket 7 at 20-800℃ are independently (10-18)×10⁻⁶. -6 K -1 Preferably, the first sealing gasket 6 and the second sealing gasket 7 are compressible sealing gaskets, and the compression ratio of the compressible sealing gaskets is preferably 20-40%.

[0045] More preferably, the first sealing gasket 6 and the second sealing gasket 7 each independently contain 15-50 wt% silicon oxide, 10-40 wt% barium oxide, 10-40 wt% magnesium oxide, 2-15 wt% aluminum oxide, 1-5 wt% yttrium-stabilized zirconium oxide, 1-5 wt% thorium oxide, and 0.5-5 wt% carbon fiber; preferably, the yttrium-stabilized zirconium oxide contains 3-8% yttrium in its molar percentage, and this material is commercially available. More preferably, the first sealing gasket 6 and the second sealing gasket 7 each independently contain 25-40 wt% silicon oxide, 20-30 wt% barium oxide, 15-30 wt% magnesium oxide, 5-10 wt% aluminum oxide, 2-4 wt% yttrium-stabilized zirconium oxide, 2-4 wt% thorium oxide, and 1-3 wt% carbon fiber. The inventors have discovered that the sealing gasket using the above-mentioned formulation system has an optimized coefficient of thermal expansion and compressibility. The combination of a specific proportion of yttrium oxide-stabilized zirconium oxide, thorium oxide, and carbon fiber reinforcement significantly improves the matching of coefficients of thermal expansion and compressibility through the interaction between the components. This enhances the stability of the sealing gasket in high-temperature environments, provides a more reliable sealing effect under extreme conditions, and reduces the risk of leakage.

[0046] By using the first sealing gasket 6 and the second sealing gasket 7 with the above-mentioned preferred formulation, a compressible sealing gasket that meets the requirements of average thermal expansion coefficient and compressibility within the range of 20-800℃ can be obtained. When such first and second sealing gaskets 6 and 7 are used in conjunction with ceramic connecting pipes 3, they have good compressibility at high temperatures and can effectively improve sealing performance.

[0047] The first and second sealing gaskets can be prepared using existing processes in the art. For example, in some preferred embodiments, the preparation methods of the first sealing gasket 6 or the second sealing gasket 7 respectively include the following steps:

[0048] (1b) After melting and quenching the raw material powder for the sealing gasket, a glass base material is obtained; the glass base material is crushed and ground to obtain glass powder; the glass powder is ground evenly with a binder and a solvent, and then formed into a sealing gasket blank; the raw material powder for the sealing gasket includes 15-50 wt% silicon oxide, 10-40 wt% barium oxide, 10-40 wt% magnesium oxide, 2-15 wt% aluminum oxide, 1-5 wt% yttrium-stabilized zirconium oxide, 1-5 wt% thorium oxide, and 0.5-5 wt% carbon fiber, preferably including 25-40 wt% silicon oxide, 20-30 wt% barium oxide, 15-30 wt% magnesium oxide, 5-10 wt% aluminum oxide, 2-4 wt% yttrium-stabilized zirconium oxide, 2-4 wt% thorium oxide, and 1-3 wt% carbon fiber; preferably, the molar percentage of yttrium oxide in the yttrium-stabilized zirconium oxide is 3-8%;

[0049] (2b) The sealing gasket blank is sintered and then mechanically processed to obtain the first sealing gasket 6 or the second sealing gasket 7.

[0050] Preferably, in step (1b), the melting is carried out under a protective atmosphere (e.g., nitrogen). Specifically, for example, the temperature is raised to 1100-1500°C and held for 1-3 hours; for example, the temperature is raised to 1100-1500°C at a heating rate of 5-15°C / min.

[0051] The average coefficients of thermal expansion of the first sealing gasket 6 and the second sealing gasket 7 obtained by the above preparation method are independently (10-18)×10 in the range of 20-800℃. -6 K -1 The compression ratios are 20-40%. The first sealing gasket 6 and the second sealing gasket 7 obtained by the above preparation method in the pipe connection assembly of the present invention have good compressibility at high temperature, which can effectively improve the sealing performance. At the same time, when used in conjunction with the ceramic connecting pipe 3 provided by the present invention, it is easy to obtain the connection parts with the required thermal expansion coefficient, thereby improving the reliability of the pipe connection.

[0052] In some examples, in step (1b), the melt obtained from the melting process is poured into deionized water for quenching.

[0053] Preferably, in step (1b), the binder is one or more of polyvinyl butyral, acrylic resin, and polymethyl methacrylate, preferably polyvinyl butyral; the amount of the binder is preferably 10-40 wt% of the amount of glass powder. Preferably, in step (1b), the solvent is one or more of ethanol, acetone, and butanone, preferably ethanol, and the amount of the solvent is, for example, 10-20 wt% of the amount of glass powder.

[0054] Preferably, in step (2b), the sintering includes: first heating the sealing gasket blank, for example, slowly heating it at a rate of 1-10°C / min to 120-180°C and holding it for 3-5 hours; then heating it to 500-550°C and holding it for 2-5 hours to remove the adhesive; and then heating it to 700-800°C and holding it for 2-10 hours for crystallization treatment. Specifically, for example, heating it to 500-550°C at a rate of 3°C / min and heating it to 700-800°C at a rate of 5°C / min.

[0055] Specifically, the mechanical processing described in step (2b) includes precisely machining the sintered sealing gasket blank according to the dimensions adapted to the grooves on the first and second flanges of the ceramic connecting pipe, including mechanical processing such as cutting, grinding, and polishing, to ensure that the obtained sealing gasket precisely matches the grooves on the first and second flanges of the ceramic connecting pipe.

[0056] In some preferred examples, the thickness of the first sealing gasket 6 and the second sealing gasket 7 is independently 1-5 mm.

[0057] In solid oxide fuel cell power generation systems, the average coefficient of thermal expansion of the metal materials used for the metal pipes connecting to the inlet and outlet pipes of the battery stack (i.e., the second metal pipe 2) and the external metal pipes (i.e., the first metal pipe 1) within the temperature range of 20-800℃ is typically (11-19)×10⁻⁶. -6 K -1 When the thermal expansion coefficients of the two metal pipe materials differ significantly, the ceramic connecting pipe 3 of this invention, in conjunction with the first and second sealing gaskets 6 and 7, particularly when the average thermal expansion coefficient is (10-13)×10 in the range of 20-800℃, can be utilized. -6 K -1 The ceramic connecting pipe 3, used in conjunction with a ceramic pipe having an average thermal expansion coefficient of (10-18)×10 in the temperature range of 20-800℃. -6 K -1The first sealing gasket 6 and the second sealing gasket 7 are provided, and the coefficients of thermal expansion of the first and second sealing gaskets 6 and 7 are located between the coefficients of thermal expansion of the first and second metal pipes 1 and 2; and the coefficient of thermal expansion of the entire connection is located between the coefficients of thermal expansion of the first metal pipe 1 and the coefficients of thermal expansion of the second metal pipe 2; this can effectively reduce the total amount of high-temperature expansion deformation of the gas transmission pipeline, more effectively reduce high-temperature stress, and can avoid gas leakage caused by excessive deformation difference to a greater extent.

[0058] The present invention also provides a pipeline connection mechanism for an electrochemical device, see below. Figure 1 and Figure 2 The pipe connection mechanism includes an external first metal pipe 1, a second metal pipe 2 that is in electrical contact with the electrochemical device, and a pipe connection assembly connecting the first metal pipe and the second metal pipe; wherein, the pipe connection assembly is the pipe connection assembly described above, and will not be repeated here.

[0059] This invention also provides the application of the electrochemical device piping connection assembly described above in an electrochemical device, preferably a solid oxide fuel cell. Using the piping connection assembly of this invention for connecting the fuel cell stack to other fuel cell stacks or other devices, systems, or components in a solid oxide fuel cell provides improved sealing and insulation reliability.

[0060] The present invention will be further illustrated by the following embodiments, but it should not be construed as the present invention being limited to these embodiments.

[0061] Where specific experimental steps or conditions are not specified in the examples, the corresponding conventional experimental steps or conditions in this technical field can be followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0062] In the following embodiments, the schematic diagrams of the electrochemical device piping connection assemblies are all referred to Figure 1-4Specifically, the electrochemical device piping connection components in the following embodiments all include connectors, a first metal fastener 4, and a second metal fastener 5. The connector includes a ceramic connecting pipe 3, a first sealing gasket 6, and a second sealing gasket 7, both of which are compressible O-rings. The ceramic connecting pipe 3 has a first flange 31 and a second flange 32 at both ends. One end of the first metal pipe 1 of the electrochemical device has a first flange 11, and one end of the second metal pipe 2 has a second flange 21. Correspondingly, in these embodiments, the first metal fastener 4 and the second metal fastener 5 are respectively a first split flange 41 and a second split flange 51, formed by splicing two flange plates. The first split flange 41 and the first flange 11 are bolted together, and the second split flange 51 and the second flange 21 are bolted together. Regarding... Figure 1-4 For detailed descriptions of the electrochemical connection components shown, please refer to the preceding text; they will not be repeated here.

[0063] Example 1:

[0064] The average coefficients of thermal expansion of the first metal pipe 1 (made of Crofer 22H) and the second metal pipe 2 (made of Inconel 625) in the range of 20-800℃ are 11.3×10⁻⁶ and 11.3×10⁻⁶, respectively. -6 K -1 With 15.3×10 -6 K -1 .

[0065] (1) Preparation of ceramic connecting pipe 3:

[0066] Weigh 110g of diopside (purity ≥95%), 250g of magnesium oxide (purity ≥99%), 187g of forsterite (purity ≥97%) and 22g of aluminum nitride (purity ≥99%), put them into a ball mill and mix them thoroughly for 5 hours, then sieve them to obtain ceramic powder;

[0067] Weigh 500g of sieved ceramic powder with a particle size less than 0.1mm and 74g of cellulose and put them into a kneader. While kneading, add 75mL of aqueous solution containing 50wt% ethanol. After kneading for 50 minutes, add 40g of emulsified silicone oil and 20mL of ethanol and continue kneading for 30 minutes. Then transfer the resulting mud to a vacuum kneader and knead it for 30 minutes under a vacuum of 0.05MPa. After sealing and aging for 12 hours, perform a second vacuum kneading at a vacuum of 0.08MPa for 20 minutes. After sealing and aging for 12 hours, perform a third vacuum kneading at a vacuum of 0.1MPa for 10 minutes. Seal and age the mud section for 24 hours to obtain mud for connecting pipes.

[0068] The clay material is poured into a mold and pressed under dry pressure at 150 MPa for 15 minutes to obtain a ceramic connecting pipe blank. The blank is then naturally dried at room temperature for 15 hours, followed by drying in an oven at 120°C (3°C / min) for 10 hours. Afterward, it is transferred to a vacuum resistance furnace and heated to 300°C (3°C / min) under a nitrogen atmosphere, held for 5 hours to remove the binder and extrusion aid. The temperature is then further increased to 1450°C (5°C / min), held for 3 hours, and then cooled at a rate of 5°C / min to obtain a sintered sample. The surface of the sintered sample is then ground and polished to obtain ceramic connecting pipe 3, denoted as ceramic connecting pipe T1. Its structural schematic diagram is shown below. Figure 2 The device has a first flange 31 and a second flange 32 at both ends, and multiple annular grooves 33 are formed on the first flange 31 and the second flange 32.

[0069] (2) Fabricate the first metal fastener 4 and the second metal fastener 5 to match the dimensions of the ceramic connecting pipe T1. The materials of the first and second metal fasteners 4 and 5 are Crofer 22H and Inconel 625, respectively. In this embodiment, the first metal fastener 4 and the second metal fastener 5 are both split flanges. See the structural diagram. Figure 2 and Figure 5 As shown, the split flange includes two flange plates, and multiple through holes evenly distributed along its axial direction are opened on the end face of the flange plates; the flange through hole of the first metal fastener 4 is adapted to the through hole of the first flange 11 of the first metal pipe 1, and the flange through hole of the second metal fastener 5 is adapted to the through hole of the second flange 21 of the second metal pipe 2.

[0070] (3) Preparation of sealing gaskets:

[0071] Weigh out 72g of silicon dioxide, 50g of barium oxide, 47g of magnesium oxide, 17g of aluminum oxide, 5.6g of yttrium-stabilized zirconium oxide 8YSZ (8mol% Y2O3-doped ZrO2), 5.2g of thorium oxide and 4g of carbon fiber, mix them and grind them thoroughly, then sieve out the fine powder (≤0.25mm) to obtain the raw material powder for sealing gaskets;

[0072] The raw material powder for sealing gaskets is placed in a crucible, transferred to a crystallization furnace, and nitrogen is continuously introduced. The temperature is raised to 1450℃ at a heating rate of 10℃ / min and held for 2 hours. Then, the molten material in the crucible is directly poured into deionized water for quenching to obtain the glass base material.

[0073] The glass base material is crushed and ground, and then passed through a 325-mesh sieve to obtain glass powder.

[0074] Weigh 100g of glass powder, 25g of polyvinyl butyral and 15g of ethanol, grind them evenly in a ball mill, transfer them to a mold, and press them into O-ring sealing gasket blanks.

[0075] The blank is heated to 150℃ at 1℃ / min and held for 5 hours; then heated to 550℃ at 3℃ / min and held for 3 hours to remove the glue; then heated to 750℃ at 5℃ / min and held for 5 hours to crystallize.

[0076] The sintered sample was mechanically processed according to the dimensions of the annular grooves on the first and second flanges of the ceramic connecting pipe T1, and then polished to obtain sealing gasket M1 with a thickness of 3mm. The first and second sealing gaskets 6 and 7 are both made of sealing gasket M1.

[0077] (4) The performance test results of ceramic connecting pipes and sealing gaskets are shown in Table 1 and Table 2.

[0078] The coefficient of thermal expansion of the samples was tested using a thermal dilatometer at a heating rate of 10℃ / min, within a range of 20-1000℃. The data in Table 1 represent the average coefficient of thermal expansion for samples between 20-800℃. The resistance of the samples was tested using an insulation resistance tester. Bending strength was tested using a universal tensile testing machine. Compression ratio was tested using a high-temperature mechanical testing system; the formula for calculating compression ratio is: Compression ratio = (Compression amount of the tested sample / Original thickness) × 100%.

[0079] Example 2:

[0080] The procedure is the same as in Example 1, except that:

[0081] The average coefficients of thermal expansion of the first metal pipe 1 (made of Crofer 22H) and the second metal pipe 2 (made of stainless steel 316L) in the range of 20-800℃ are 11.3×10⁻⁶ and 11.3×10⁻⁶, respectively. -6 K -1 With 16.5×10 -6 K -1 .

[0082] In step (1), when preparing the ceramic connecting pipe 3, 81g of diopside (purity ≥95%), 250g of magnesium oxide (purity ≥99%), 158g of forsterite (purity ≥97%) and 20g of aluminum nitride (purity ≥99%) were weighed and placed in a ball mill for ball milling and mixing; the remaining operations were carried out in accordance with Example 1.

[0083] In step (2), the materials of the first metal fastener 4 and the second metal fastener 5 are selected as Crofer 22H and stainless steel 316L, respectively.

[0084] In step (3), when preparing the sealing gasket, 54g of silicon oxide, 60g of barium oxide, 51.8g of magnesium oxide, 19g of aluminum oxide, 7.4g of yttrium-stabilized zirconium oxide 8YSZ, 5.8g of thorium oxide and 3.2g of carbon fiber were weighed, mixed and then thoroughly ground; the remaining operations were carried out in accordance with Example 1.

[0085] Example 3:

[0086] The procedure is the same as in Example 1, except that:

[0087] The average coefficients of thermal expansion of the first metal pipe 1 and the second metal pipe 2 in the range of 20-800℃ are 11.3×10⁻⁶ and 11.3×10⁻⁶, respectively. -6 K -1 With 13.6×10 -6 K -1 .

[0088] In step (1), when preparing the ceramic connecting pipe 3, 122g of diopside (purity ≥95%), 250g of magnesium oxide (purity ≥99%), 177g of forsterite (purity ≥97%) and 23g of aluminum nitride (purity ≥99%) were weighed and placed in a ball mill for ball milling and mixing; the remaining operations were carried out in accordance with Example 1.

[0089] In step (2), both the first and second metal fasteners are made of stainless steel 441 (with an average coefficient of thermal expansion of 12.4 × 10⁻⁶ in the range of 20-800℃). -6 K -1 );

[0090] In step (3), when preparing the sealing gasket, 78g of silicon oxide, 40g of barium oxide, 59g of magnesium oxide, 10.5g of aluminum oxide, 4.2g of yttrium-stabilized zirconium oxide 8YSZ, 4.4g of thorium oxide and 5.0g of carbon fiber were weighed, mixed and then thoroughly ground; the remaining operations were carried out in accordance with Example 1.

[0091] Example 4:

[0092] The procedure is the same as in Example 1, except that:

[0093] The average coefficients of thermal expansion of the first metal pipe 1 and the second metal pipe 2 in the range of 20-800℃ are 12.4×10⁻⁶. -6 K -1 With 16.5×10 -6 K -1 .

[0094] In step (1), when preparing the ceramic connecting pipe 3, 182g of diopside (purity ≥95%), 250g of magnesium oxide (purity ≥99%), 247g of forsterite (purity ≥97%) and 34g of aluminum nitride (purity ≥99%) were weighed and placed in a ball mill for ball milling and mixing; the remaining operations were carried out in accordance with Example 1.

[0095] In step (2), the materials of the first metal fastener and the second metal fastener are respectively selected as stainless steel 441 (with an average coefficient of thermal expansion of 12.4 × 10⁻⁶ in the range of 20-800℃). -6 K -1 ), 316L (with an average coefficient of thermal expansion of 16.5×10 in the range of 20-800℃). -6 K -1 );

[0096] In step (3), when preparing the sealing gasket, 50g of silicon oxide, 72.6g of barium oxide, 52.5g of magnesium oxide, 11.2g of aluminum oxide, 5.4g of yttrium-stabilized zirconium oxide 8YSZ, 5.2g of thorium oxide and 3.0g of carbon fiber were weighed, mixed and then thoroughly ground; the remaining operations were carried out in accordance with Example 1.

[0097] Example 5:

[0098] The procedure is the same as in Example 1, except that:

[0099] The average coefficients of thermal expansion of the first metal pipe 1 and the second metal pipe 2 in the range of 20-800℃ are 13.6×10⁻⁶. -6 K -1 With 18.5×10 -6 K -1 .

[0100] In step (1), when preparing the ceramic connecting pipe 3, 154g of diopside (purity ≥95%), 270g of magnesium oxide (purity ≥99%), 76g of forsterite (purity ≥97%) and 16g of aluminum nitride (purity ≥99%) were weighed and placed in a ball mill for ball milling and mixing; the remaining operations were carried out in accordance with Example 1.

[0101] In step (2), the materials of the first metal fastener and the second metal fastener are respectively selected as Incoloy 800 (with an average coefficient of thermal expansion of 13.6 × 10⁻⁶ in the range of 20-800℃). -6 K -1 ), Stainless steel 310S (with an average coefficient of thermal expansion of 18.5 × 10⁻⁶ in the temperature range of 20-800℃). -6 K -1 ).

[0102] In step (3), when preparing the sealing gasket, 35.8g of silicon oxide, 78g of barium oxide, 58.4g of magnesium oxide, 9.2g of aluminum oxide, 6.6g of yttrium-stabilized zirconium oxide 8YSZ, 10.0g of thorium oxide and 2.0g of carbon fiber were weighed, mixed and then thoroughly ground; the remaining operations were carried out in accordance with Example 1.

[0103] Example 6:

[0104] The procedure is the same as in Example 1, except that:

[0105] The average coefficients of thermal expansion of the first metal pipe 1 and the second metal pipe 2 in the range of 20-800℃ are 11.3×10⁻⁶ and 11.3×10⁻⁶, respectively. -6 K -1 With 12.4×10 -6 K -1 .

[0106] In step (1), when preparing the ceramic connecting pipe 3, 95g of diopside (purity ≥95%), 250g of magnesium oxide (purity ≥99%), 230g of forsterite (purity ≥97%) and 48g of aluminum nitride (purity ≥99%) were weighed and placed in a ball mill for ball milling and mixing; the remaining operations were carried out in accordance with Example 1.

[0107] In step (2), both the first and second metal fasteners are made of stainless steel 441 (with an average coefficient of thermal expansion of 12.4 × 10⁻⁶ in the range of 20-800℃). -6 K -1 );

[0108] In step (3), when preparing the sealing gasket, 77g of silicon oxide, 58.2g of barium oxide, 29.0g of magnesium oxide, 15.2g of aluminum oxide, 8.6g of yttrium-stabilized zirconium oxide 8YSZ, 5.8g of thorium oxide and 6.0g of carbon fiber were weighed, mixed and thoroughly ground; the remaining operations were carried out in accordance with Example 1.

[0109] Comparative Example 1

[0110] The procedure is the same as in Example 1, except that:

[0111] In step (1), when preparing the ceramic connecting pipe 3, 246g of diopside (purity ≥95%), 125g of magnesium oxide (purity ≥99%), 280g of forsterite (purity ≥97%) and 30g of aluminum nitride (purity ≥99%) were weighed and placed in a ball mill for ball milling and mixing; the remaining operations were carried out in accordance with Example 1.

[0112] Comparative Example 2

[0113] The procedure is the same as in Example 1, except that:

[0114] In step (3), when preparing the sealing gasket, 110g of silicon oxide, 19.6g of barium oxide, 38.6g of magnesium oxide, 17.0g of aluminum oxide, 5.6g of yttrium-stabilized zirconium oxide 8YSZ, 5.2g of thorium oxide and 4.0g of carbon fiber were weighed, mixed and thoroughly ground; the remaining operations were carried out in accordance with Example 1.

[0115] Table 1. Performance test results of ceramic connecting pipes and sealing gaskets in Examples 1-6

[0116]

[0117] In Table 1, the "coefficient of thermal expansion" refers to the average coefficient of thermal expansion in the range of 20-800℃.

[0118] Test case

[0119] Each pipe connection component was prepared according to the embodiments and Comparative Examples 1-2. Each pipe connection component was connected to the first metal pipe 1 and the second metal pipe 2 in the electrochemical device, and then heated together to 800°C, held at that temperature for 24 hours, and then cooled to room temperature for airtightness testing. The airtightness testing method involved sealing one end of the first metal pipe 1 or the second metal pipe 2 and inflating it through the other end. Compressed air was then used to pressurize the inside of the pipe to a predetermined test pressure (1 MPa) and maintained for a certain period to stabilize the pressure. The soap bubble method was used to test the seal, i.e., soapy water was applied to the connection points between the connectors and the first or second metal pipes 1 and 2, and the presence of bubbles was observed. The results showed that no bubbles were found between the connectors and the sealing surfaces of the connected metal pipes in each embodiment, indicating good sealing performance. However, bubbles were found between the connectors and the sealing surfaces of the connected metal pipes in Comparative Examples 1 and 2, indicating leakage. Therefore, the connectors provided in the embodiments of the present invention have better sealing performance.

[0120] The above experiments demonstrate that the connector provided by this invention is effective in providing an insulating and sealed connection between an external metal pipe (i.e., the first metal pipe) and a metal pipe that is in electrical contact with the battery stack (i.e., the second metal pipe). Simultaneously, the thermal expansion coefficient of the connector is controlled between that of the first and second metal pipes, and the absolute value of the difference between the thermal expansion coefficients of the connector and the first and second metal pipes is less than 3.5 × 10⁻⁶. -6 K -1This invention can simultaneously meet the requirements for gas transmission, sealing, and insulation between the battery stack and external metal pipes at high temperatures, exhibiting high sealing and insulation reliability. In contrast, the connectors in the comparative example, which do not meet the requirements of this invention, have poor sealing and insulation reliability when used in electrochemical devices to connect electrically contacting metal pipes and external metal pipes. Temperature changes in the connection components can cause thermal stress and seal failure, making it impossible to meet the requirements for gas transmission and sealing between the battery stack and external metal pipes at high temperatures.

[0121] It is readily understood that the above embodiments are merely illustrative examples for clear explanation and do not imply that the invention is limited thereto. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A pipeline connection assembly for an electrochemical device, characterized in that, The pipe connection assembly includes a connector for connecting an external first metal pipe and a second metal pipe that is in electrical contact with the electrochemical device. The connector includes a first sealing gasket, a ceramic connecting pipe, and a second sealing gasket, which are sequentially disposed between the first metal pipe and the second metal pipe; when the connector is connected between the first metal pipe and the second metal pipe, the ceramic connecting pipe can communicate with the first metal pipe and the second metal pipe. The coefficient of thermal expansion of the connector is between that of the first metal pipe and the second metal pipe. Furthermore, the absolute value of the difference between the thermal expansion coefficient of the connector and the thermal expansion coefficients of the first and second metal pipes is less than 3.5 × 10⁻⁶. -6 K -1 .

2. The electrochemical device pipeline connection assembly according to claim 1, characterized in that, The pipe connection assembly also includes a first metal fastener and a second metal fastener. The first metal fastener is used to securely connect the connector to the first metal pipe; The second metal fastener is used to securely connect the connector to the second metal pipe; Preferably, the material of the first metal fastener is the same as that of the first metal pipe, or the absolute value of the difference between the coefficient of thermal expansion of the first metal fastener and the coefficient of thermal expansion of the first metal pipe is less than 1.5 × 10⁻⁶. -6 K -1 ; Preferably, the material of the second metal fastener is the same as that of the second metal pipe, or the absolute value of the difference between the coefficient of thermal expansion of the second metal fastener and the coefficient of thermal expansion of the second metal pipe is less than 1.5 × 10⁻⁶. -6 K -1 .

3. The electrochemical device pipeline connection assembly according to claim 2, characterized in that, The first metal pipe has a first flange at one end, and the second metal pipe has a second flange at one end. The ceramic connecting pipe is provided with a first flange and a second flange at both ends; The first sealing gasket is used to be sandwiched between the first flange and the first flange; The second sealing gasket is used to be sandwiched between the second flange and the second flange; Preferably, the first sealing gasket is a compressible sealing gasket, and the surface of the first flange that contacts the first sealing gasket is provided with a groove, preferably an annular groove; Preferably, the second sealing gasket is a compressible sealing gasket, and the surface of the second flange that contacts the second sealing gasket is provided with a groove, preferably an annular groove; Preferably, the first flange and the second flange are both L-shaped flanges.

4. The electrochemical device pipeline connection assembly according to claim 3, characterized in that, The first metal fastener is a first split flange adapted to the first flange; The second metal fastener is a second split flange adapted to the second flange; The first split flange and the second split flange are each composed of multiple flange pieces spliced ​​together; When the ceramic connecting pipe is fastened to the first flange through the first split flange, the first split flange is sleeved outside the first flange of the ceramic connecting pipe; When the ceramic connecting pipe is fastened to the second flange through the second split flange, the second split flange is sleeved outside the second flange of the ceramic connecting pipe; Preferably, the first split flange is provided with a first limiting groove for accommodating the first flange and the first sealing gasket; when the ceramic connecting pipe is fastened to the first flange through the first split flange, the first flange abuts against the first split flange through the first limiting groove. Preferably, the second split flange is provided with a second limiting groove for accommodating the second flange and the second sealing gasket; when the ceramic connecting pipe is fastened to the second flange through the second split flange, the second flange abuts against the second split flange through the second limiting groove; Preferably, each flange piece of the first split flange has a splicing structure that enables the flange pieces to be spliced ​​together to form the first split flange; each flange piece of the second split flange has a splicing structure that enables the flange pieces to be spliced ​​together to form the second split flange; more preferably, the splicing structure includes mutually adaptable positioning grooves and positioning protrusions. Preferably, the first split flange has a connection structure for bolting to the first flange, and the second split flange has a connection structure for bolting to the second flange.

5. The electrochemical device piping connection assembly according to any one of claims 1-4, characterized in that, The average coefficient of thermal expansion of the ceramic connecting pipe in the temperature range of 20-800℃ is (10-13)×10. -6 K -1 The flexural strength is 50-200MPa, and the electrical resistance is (5-10)×10⁻⁶. 13 Ω; Preferably, the ceramic connecting pipe contains 10-30 wt% diopside, 25-60 wt% magnesium oxide, 15-40 wt% forsterite, and 1-8 wt% aluminum nitride. More preferably, the ceramic connecting pipe contains 15-25 wt% diopside, 35-50 wt% magnesium oxide, 20-35 wt% forsterite, and 3-5 wt% aluminum nitride.

6. The electrochemical device piping connection assembly according to any one of claims 1-5, characterized in that, The preparation steps of the ceramic connecting pipe include: (1a) The ceramic powder and binder are mixed evenly, and the mixture is kneaded to obtain a mixed clay material; the ceramic powder includes 10-30 wt% diopside, 25-60 wt% magnesium oxide, 15-40 wt% forsterite and 1-8 wt% aluminum nitride; more preferably, the ceramic powder includes 15-25 wt% diopside, 35-50 wt% magnesium oxide, 20-35 wt% forsterite and 3-5 wt% aluminum nitride; (2a) The mixed clay is kneaded and then sealed and aged; the resulting clay is shaped to obtain a ceramic connecting pipe blank; the blank is dried and sintered, and the sintered sample is mechanically treated to obtain the ceramic connecting pipe. Preferably, in step (1a), the binder is one or more of dextrin, polyvinyl alcohol, polyacrylic acid, and cellulose; preferably, the amount of the binder is 5-30 wt% of the amount of ceramic powder. Preferably, in step (1a), when kneading the clay, a mixed solvent of ethanol and water is added, preferably the mass percentage of ethanol in the mixed solvent is 40-60%, and preferably the amount of the mixed solvent is 10-20 wt% of the amount of ceramic powder; more preferably, in step (1a), after kneading with the mixed solvent of ethanol and water, an extrusion aid and an ethanol solvent are added to continue kneading, preferably one or more of emulsified silicone oil, aluminum stearate, and graphite, preferably the amount of the extrusion aid is 5-15 wt% of the amount of ceramic powder, and preferably the amount of the ethanol solvent is 2-8 wt% of the amount of ceramic powder; Preferably, in step (2a), the sintering process includes: first holding at 200-400℃ for 2-10 hours, and then raising the temperature to 1400-1600℃ and holding for 2-5 hours.

7. The electrochemical device piping connection assembly according to any one of claims 1-6, characterized in that, The coefficients of thermal expansion of the first sealing gasket and the second sealing gasket are respectively located between the coefficients of thermal expansion of the first metal pipe and the coefficients of thermal expansion of the second metal pipe; Preferably, the average coefficients of thermal expansion of the first sealing gasket and the second sealing gasket in the range of 20-800°C are independently (10-18)×10⁻⁶. -6 K -1 ; Preferably, the first sealing gasket and the second sealing gasket are both compressible sealing gaskets, and preferably the compression ratio of the compressible sealing gaskets is 20-40% respectively; Preferably, the thickness of the first sealing gasket and the second sealing gasket are each 1-5 mm independently; Preferably, the first sealing gasket and the second sealing gasket each independently contain 15-50 wt% silicon oxide, 10-40 wt% barium oxide, 10-40 wt% magnesium oxide, 2-15 wt% aluminum oxide, 1-5 wt% yttrium-stabilized zirconium oxide, 1-5 wt% thorium oxide, and 0.5-5 wt% carbon fiber; preferably, the molar percentage of yttrium oxide in the yttrium-stabilized zirconium oxide is 3-8%. More preferably, the first sealing gasket and the second sealing gasket each independently contain 25-40 wt% silicon oxide, 20-30 wt% barium oxide, 15-30 wt% magnesium oxide, 5-10 wt% aluminum oxide, 2-4 wt% yttrium-stabilized zirconium oxide, 2-4 wt% thorium oxide, and 1-3 wt% carbon fiber.

8. The electrochemical device piping connection assembly according to any one of claims 1-7, characterized in that, The preparation steps of the first sealing gasket or the second sealing gasket respectively include: (1b) After melting and quenching the raw material powder of the sealing gasket, a glass base material is obtained; the glass base material is crushed and ground to obtain glass powder; the glass powder is ground evenly with binder and solvent, and then formed into a sealing gasket blank. The sealing gasket raw material powder comprises 15-50 wt% silicon dioxide, 10-40 wt% barium oxide, 10-40 wt% magnesium oxide, 2-15 wt% aluminum oxide, 1-5 wt% yttrium-stabilized zirconium oxide, 1-5 wt% thorium oxide, and 0.5-5 wt% carbon fiber; preferably, it comprises 25-40 wt% silicon dioxide, 20-30 wt% barium oxide, 15-30 wt% magnesium oxide, 5-10 wt% aluminum oxide, 2-4 wt% yttrium-stabilized zirconium oxide, 2-4 wt% thorium oxide, and 1-3 wt% carbon fiber; preferably, the molar percentage of yttrium oxide in the yttrium-stabilized zirconium oxide is 3-8%. (2b) The sealing gasket blank is sintered and then mechanically processed to obtain the first sealing gasket or the second sealing gasket. Preferably, in step (1b), the melting is carried out at 1100-1500°C under a protective atmosphere; Preferably, in step (1b), the binder is one or more of polyvinyl butyral, acrylic resin and polymethyl methacrylate; the amount of the binder is preferably 10-40 wt% of the amount of glass powder. Preferably, in step (1b), the solvent is one or more of ethanol, acetone and butanone, and the amount of the solvent is preferably 10-20 wt% of the amount of glass powder. Preferably, in step (2b), the sintering includes: first heating the sealing gasket blank to 120-180℃ and holding it for 3-5 hours; then raising the temperature to 500-550℃ and holding it for 2-5 hours; and then raising the temperature to 700-800℃ and holding it for 2-10 hours.

9. A pipeline connection mechanism for an electrochemical device, characterized in that, The pipe connection mechanism includes an external first metal pipe, a second metal pipe that is in electrical contact with the electrochemical device, and a pipe connection assembly connecting the first metal pipe and the second metal pipe. The pipe connection assembly is the pipe connection assembly according to any one of claims 1-8.

10. The application of the electrochemical device pipeline connection assembly according to any one of claims 1-8 in an electrochemical device, preferably, the electrochemical device is a solid oxide fuel cell.

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