Solid oxide fuel cell stack and preparation method thereof

Abstract

The invention provides a solid oxide fuel cell stack and a preparation method thereof. The solid oxide fuel cell stack comprises a clamping assembly and a reactor core assembly clamped in the clamping assembly, wherein the reactor core assembly comprises a battery repeating unit stacked in the clamping assembly and a separator arranged between the battery repeating unit and the clamping assembly. The stack with a full-sealed structure is designed and prepared through a coupling process of series stacking, in-situ packaging and pressure sintering, so that the problems of poor sealing performance, low reliability, low preparation efficiency and relatively high energy consumption of the existing solid oxide fuel cell stack can be effectively solved.

Description

Technical Field

[0001] The present invention relates to the field of new energy technologies, and more specifically, to a solid oxide fuel cell stack and a preparation method thereof. Background Art

[0002] Solid oxide fuel cells (SOFCs) are energy conversion devices that directly generate electricity and heat through the electrochemical reaction between a reductant in the anode fuel and an oxidant in the cathode fuel. Due to their high efficiency and low pollutant emissions, they are considered a clean, low-carbon, safe, and efficient method of power generation. SOFC stacks can generate power from tens of watts to hundreds of megawatts, and have a wide range of applications, including distributed power generation, hydrogen production, combined energy storage, microgrids, military applications, combined heat and power systems in power plants, ships, large vehicles, drones, and large data centers.

[0003] SOFC has a variety of different structures. For a flat single cell, one cell can usually generate a voltage of 0.5-1V and a power of 20-50W. In order to produce a sufficiently high output power, several SOFC cells need to be stacked to form a SOFC stack (SOFC includes components such as anode, electrolyte, cathode and connector. These components are formed into a SOFC stack through specific structural design and assembly technology).

[0004] Existing SOFC stack preparation technologies mainly include sintering technology and assembly technology. Among them, sintering technology mainly involves pressing multiple SOFC components together under high temperature and high pressure to form a stack structure; assembly technology mainly involves connecting multiple SOFC components together in series or parallel to form a stack.

[0005] However, existing SOFC stack fabrication technology still has several problems and limitations. First, it requires multiple sintering and assembly steps, resulting in complex processes, severe leakage, long production cycles, high costs, and potential safety hazards. Second, existing technologies cannot guarantee the consistency and reliability of stacks during fabrication, thus affecting their discharge performance and service life. Finally, existing technologies require high temperatures during stack fabrication, resulting in high energy consumption and incompatibility with achieving the dual carbon goals.

[0006] Therefore, there is an urgent need for a SOFC stack structure and preparation method that can achieve high sealing, high reliability, high efficiency and relatively low energy consumption. Summary of the Invention

[0007] In view of the above problems, the purpose of the present invention is to provide a solid oxide fuel cell stack and a preparation method thereof to solve the problems of poor sealing, low reliability, low preparation efficiency and relatively high energy consumption of existing solid oxide fuel cell stacks.

[0008] The solid oxide fuel cell stack provided by the present invention includes a clamping assembly and a core assembly clamped in the clamping assembly; wherein, the core assembly includes a battery repeating unit stacked in the clamping assembly and an isolation member arranged between the battery repeating unit and the clamping assembly.

[0009] In addition, a preferred solution is that the clamping assembly includes a top end plate and a bottom end plate, and the isolation member includes a top isolation member and a bottom isolation member, wherein,

[0010] The top separator is disposed between the battery repeating unit and the top end plate, and the bottom separator is disposed between the battery repeating unit and the bottom end plate.

[0011] In addition, a preferred solution is that the top isolation member includes a top mica plate, a top conductive plate, a top silver paste and silver mesh, and a top light plate, which are arranged in sequence from top to bottom; wherein the top mica plate is arranged on a side close to the top end plate, and the top light plate is arranged on a side close to the battery repeating unit;

[0012] The bottom isolation member includes a bottom mica plate, a bottom conductive plate, a bottom silver paste and silver mesh, and a bottom light plate arranged in sequence from bottom to top; wherein, the bottom mica plate is arranged on a side close to the bottom end plate, and the bottom light plate is arranged on a side close to the battery repeating unit.

[0013] In addition, a preferred solution is that n battery repeating units are stacked between the top end plate and the bottom end plate; wherein n is an integer, and n≥1.

[0014] In addition, a preferred solution is that the battery repeating unit includes a first battery cell, a connector and a first nickel mesh; wherein the connector is arranged on a side of the first battery cell close to the top end plate, and the first nickel mesh is arranged on a side of the first battery cell close to the bottom end plate.

[0015] In addition, a preferred solution is that a battery supplement unit is arranged between the battery repeating unit in the uppermost layer and the top light panel; wherein, the battery supplement unit includes a second battery cell, a second nickel mesh and a silver mesh; wherein, the silver mesh is arranged on the side of the second battery cell close to the top light panel, and the second nickel mesh is arranged on the side of the second battery cell close to the battery repeating unit.

[0016] In addition, preferably, the connecting piece is a ferritic stainless steel connecting piece.

[0017] In addition, preferably, the battery piece is one of a yttrium-zirconium-based anode-supported battery, a yttrium-zirconium-based electrolyte-supported battery, a scandium-zirconium-based anode-supported battery, and a scandium-zirconium-based electrolyte-supported single battery.

[0018] In addition, preferably, a U-shaped gas path is arranged in the core assembly, and an air inlet and an air outlet are arranged on the top end plate and the bottom end plate, respectively; and the two ends of the U-shaped gas path are connected to the air inlet and the air outlet, respectively.

[0019] In another aspect, the present application also provides a preparation method of the solid oxide fuel cell stack as described above, and the preparation method comprises:

[0020] The n pool repeating units and the battery supplementing unit are clamped in the clamping assembly in a series stacking manner to form an initial cell stack;

[0021] The edges of the gas path grooves between adjacent components in the initial cell stack are sealed by dispensing sealant, and then pressure is applied to complete in-situ packaging of the initial cell stack;

[0022] The in-situ packaged cell stack is placed in a stack sintering furnace for pressure assembly sintering.

[0023] Compared with the prior art, the solid oxide fuel cell stack and the preparation method thereof according to the present application have the following beneficial effects:

[0024] The solid oxide fuel cell stack and the preparation method thereof provided by the present application can realize rapid series stacking of multiple cells by self-designing clamping assemblies, separators, battery repeating units and other components, can significantly reduce the number of subsequent sintering and assembly (only one sintering and one assembly are used for the same batch of batteries), can strengthen sealing effect, can speed up production rhythm, and can reduce production cost; in addition, the preparation method of the solid oxide fuel cell stack provided by the present application can effectively ensure the consistency and reliability of the stack, can improve production efficiency, and is conducive to realizing batch production; in addition, the solid oxide fuel cell stack provided by the present application can realize higher output power at a lower temperature, can not only reduce energy consumption and improve the output power of the stack, but also can prolong the service life of the stack.

[0025] To the accomplishment of the foregoing and related ends, one or more aspects of the application, as generally described herein, include the features set forth in the claims appended hereto. These and other aspects, features, and advantages of the present application will become apparent to those of ordinary skill in the art from the following detailed description, which, taken in conjunction with the accompanying drawings, discloses various embodiments. Those skilled in the art will further appreciate that the BRIEF DESCRIPTION OF DRAWINGS

[0026] Other objects and advantages of the application will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the accompanying drawings, discloses various embodiments. Those skilled in the art will further appreciate that the

[0027] Figure 1 A perspective view of a solid oxide fuel cell stack according to an embodiment of the present application,

[0028] Figure 2 A front view of a cross-sectional structure of a solid oxide fuel cell stack according to an embodiment of the present application;

[0029] Figure 3 A flow chart of a method of manufacturing a solid oxide fuel cell stack according to an embodiment of the present application;

[0030] Figure 4 A graph of a gas tightness test of a solid oxide fuel cell stack according to an embodiment (Example 1 and Example 2) of the present application;

[0031] Figure 5 A graph of an open circuit voltage (OCV) test of a solid oxide fuel cell stack according to an embodiment (Example 1 and Example 2) of the present application;

[0032] Figure 6 A graph of a performance comparison of a solid oxide fuel cell stack according to an embodiment (Example 1 and Example 2) of the present application;

[0033] Reference numerals: 1, anode electrode post, 2, cathode electrode post, 3, anode fuel inlet gas path, 4, anode fuel outlet gas path, 5, cathode fuel inlet gas path, 6, cathode fuel outlet gas path, 7, fastener, 8, top end plate, 9, bottom end plate, 10, top mica plate, 11, bottom mica plate, 12, top conductive plate, 13, bottom conductive plate, 14, core assembly, 15, cell repeating unit, 16, top silver paste silver mesh, 17, bottom silver paste silver mesh, 18, top light plate, 19, bottom light plate, 20, connecting tab, 21, first cell tab, 22, first nickel mesh, 23, second nickel mesh, 24, second cell tab, 25, silver mesh. DETAILED DESCRIPTION

[0034] In the following description, for illustrative purposes, numerous specific details are set forth to provide a comprehensive understanding of one or more embodiments. However, it will be apparent that the embodiments may be practiced without these specific details. In other examples, well-known structures and devices are shown in block diagram form to facilitate description of one or more embodiments.

[0035] Figure 1 The solid oxide fuel cell stack according to an embodiment of the present invention is shown in FIG. Figure 2 The main cross-sectional structure of the solid oxide fuel cell stack according to an embodiment of the present invention is shown. Figure 1 and Figure 2 It can be seen that the solid oxide fuel cell stack provided by the present invention includes a clamping assembly for assembling fuel cells in series and a core assembly (including battery cells serving as fuel cells) clamped in the clamping assembly in a series assembly manner; wherein, the core assembly includes battery repeating units stacked in the clamping assembly and an isolation member arranged between the battery repeating unit and the clamping assembly, and the isolation member is used to isolate the battery repeating unit from the clamping assembly.

[0036] Specifically, the clamping assembly includes a top end plate 8 and a bottom end plate 9, and the spacers include a top spacer and a bottom spacer. The top spacer is disposed between the repeating cell unit and the top end plate to isolate the repeating cell unit from the top end plate, and the bottom spacer is disposed between the repeating cell unit and the bottom end plate to isolate the repeating cell unit from the bottom end plate. Furthermore, to enhance the stability of the entire stack, the clamping assembly can be connected and fastened to the core assembly via fasteners 7 (e.g., bolts).

[0037] It should be noted that the clamping assembly (including the top end plate and the bottom end plate) in the solid oxide fuel cell stack provided in the embodiment of the present invention can isolate the core assembly 14 from the external environment, and can complete the connection with the external gas supply system and the mutual isolation of different gas paths through the air inlet and air outlet provided therein. In addition, it should be noted that in order to realize signal transmission, a conductive column can be welded on the clamping assembly, and the electrical signal is led out through the conductive column. Specifically, the conductive column can include an anode electrode column 1 and a cathode electrode column 2; wherein the anode electrode column 1 is connected to the anode component in the core assembly, and the cathode electrode column 2 is connected to the cathode component in the core assembly.

[0038] In a specific embodiment of the present invention, the top insulator may include a top mica board 10, a top conductive board 12, a top silver paste and silver mesh 16, and a top light board 18 arranged in sequence from top to bottom; wherein, the top mica board 10 is arranged on a side close to the top end plate 8, and the top light board 18 is arranged on a side close to the battery repeating unit 15; the bottom insulator may include a bottom mica board 11, a bottom conductive board 13, a bottom silver paste and silver mesh 17, and a bottom light board 19 arranged in sequence from bottom to top; wherein, the bottom mica board 11 is arranged on a side close to the bottom end plate 9, and the bottom light board 19 is arranged on a side close to the battery repeating unit 15.

[0039] Furthermore, a plurality of battery repetition units 15 (e.g., n; wherein n is an integer, n≥1, and n is preferably 1 to 30) are stacked between the top end plate 8 and the bottom end plate 9; and the battery repetition unit 15 includes a first battery cell 21, a connector 20, and a first nickel mesh 22; wherein the connector 20 is arranged on a side of the first battery cell 21 close to the top end plate 8, and the first nickel mesh 22 is arranged on a side of the first battery cell 21 close to the bottom end plate 9.

[0040] Furthermore, a battery supplement unit may be provided between the topmost battery repeating unit 15 and the top light panel 18; wherein the battery supplement unit includes a second battery cell 24, a second nickel mesh 23 and a silver mesh 25; wherein the silver mesh 25 is provided on the side of the second battery cell 24 close to the top light panel 18, and the second nickel mesh 23 is provided on the side of the second battery cell 24 close to the battery repeating unit 15.

[0041] The following is combined with Figure 2 The structure of the solid oxide fuel cell stack provided by the present invention is described in detail.

[0042] The core assembly is arranged between the bottom end plate 9 and the top end plate 8 of the clamping assembly. When viewed from above, it is a square of the same size as the (SOFC) cell sheet and consists of a top insulation member, a cell supplement unit, multiple cell repeating units and a stack of bottom insulation members.

[0043] The entire solid oxide fuel cell stack includes, from bottom to top, a bottom end plate 9, a bottom mica plate 11 (insulation function, no need for sealing), a bottom conductive plate 13 (needs glue dispensing sealing material), a bottom silver paste silver mesh 17 (for soft contact and current collection), a bottom light plate 19 (needs glue dispensing sealing material), a plurality of battery repeating units 15, a second nickel mesh 23 (for anode current collection), a second battery cell 24 (needs glue dispensing sealing material), a silver mesh 25 (for current collection), a top light plate 18 (needs glue dispensing sealing material), a top silver paste silver mesh 16 (for soft contact and current collection), a top conductive plate 12 (needs glue dispensing sealing material), a bottom conductive plate 13 (needs glue dispensing sealing material), a bottom conductive plate 14 (needs glue dispensing sealing material), a bottom conductive plate 15 (needs glue dispensing sealing material), a bottom conductive plate 16 ... Glue dispensing sealing material), top mica board 10 (needs glue dispensing sealing material), top end plate 8 (needs glue dispensing sealing material); wherein, the bottom isolator includes bottom mica board 9, bottom conductive plate 11, bottom silver paste silver mesh, bottom light board; the top isolator includes top light board, top silver paste silver mesh, top conductive plate 13, top mica board 19; the battery repeating unit includes: a first battery cell 21 (needs glue dispensing sealing material), a first nickel mesh 22 (anode current collector) and a connecting piece 20 (needs glue dispensing sealing material); the battery supplement unit includes a second nickel mesh 23, a second battery cell 24, and a silver mesh 25.

[0044] It should be noted that a first nickel mesh 22 is provided between the anode side (lower side) of the first cell 21 and the connector 20 (belonging to another cell repeating unit). The first nickel mesh 22 is coated with anode current collecting slurry. A silver mesh (including the top silver mesh and the bottom silver mesh) coated with silver paste is provided between the bare plate (including the top bare plate and the bottom bare plate) and the conductive plate (including the top conductive plate and the bottom conductive plate). A silver mesh can be added between the cathode and the top bare plate of the second cell to enhance the conductive performance. In addition, the area of ​​the silver mesh and the nickel mesh (including the first nickel mesh and the second nickel mesh) must be smaller than the area of ​​the silk-screened current collecting layer of the cell (including the first cell and the second cell), and cannot be too close to the edge of the current collecting layer to avoid contact with the undried sealant during the movement of the battery stack, resulting in gaps and affecting the sealing effect.

[0045] Furthermore, a U-shaped gas path is provided within the core assembly, and an air inlet and an air outlet are provided on the top end plate; wherein, the two ends of the U-shaped gas path are connected to the air inlet and the air outlet, respectively. It should be noted that the gas path distribution of the entire solid oxide fuel cell stack is a fully enclosed structure gas path for fuel gas (such as hydrogen) and air, and the gas path opening is located on the top end plate, which serves as the air inlet and gas outlet, respectively. Gas paths for air and gas are formed within the stack, and the gas paths for air and gas are both "U"-shaped from top to bottom. Corresponding partial gas paths are provided on all four sides of the top mica plate and the top conductive plate, while corresponding partial gas paths are not required for the bottom mica plate and the conductive plate.

[0046] The following combination Figure 1 The gas path inside the solid oxide fuel cell stack provided by the present invention is described in detail.Figure 1 It can be seen that an anode fuel inlet path 3 (corresponding to the air inlet) and an anode fuel outlet path 4 (corresponding to the air outlet) are respectively arranged on the left and right sides of the top end plate, and the two ends of a horizontal "U"-shaped gas path formed inside the fuel cell stack are respectively connected to the anode fuel inlet path 3 and the anode fuel outlet path 4; a cathode fuel inlet path 5 (corresponding to the air inlet) and a cathode fuel outlet path (6 corresponding to the air outlet) are respectively arranged on the front and rear sides of the top end plate, and the two ends of a longitudinal "U"-shaped gas path formed inside the fuel cell stack are respectively connected to the cathode fuel inlet path 5 and the cathode fuel outlet path 6; among them, the horizontal "U"-shaped gas path and the longitudinal "U"-shaped gas path are cross-distributed.

[0047] Furthermore, for each of the two adjacent battery cells connected in series, gas paths for transporting fuel and air are required. These two gas paths constitute the mutually sealed and isolated anode and cathode gas paths of the battery cells. Specifically, grooves are provided on the upper and lower surfaces of the connector. The grooves, together with the sealing material and the battery cells, form a gap with an inlet and an outlet, which serves as the internal gas path of the stack, through which oxygen and fuel gas flow respectively. The gas path distribution design in the solid oxide fuel cell stack provided by the present invention is a cross-flow distribution, with the upper grooves perpendicular to the lower grooves, and the oxygen inlet and outlet and the fuel gas inlet and outlet are arranged on the four sides of the stack.

[0048] It should also be noted that due to the long transfer path of oxygen from the cathode side to the cathode ribs, the oxygen concentration is lower under the cathode ribs and higher under the oxygen channels, resulting in a larger mass transfer resistance (the hydrogen concentration on the anode side also shows a similar pattern). The fuel cell stack has simultaneous coupling effects between hydrogen concentration, oxygen concentration, temperature, water vapor, and current density. The arrangement of the cross-flow channels provided by the present invention can make the current density present an isolated point distribution, with a higher current density at the intersection of the cathode ribs and the anode ribs, and a lower current density at the intersection of the cathode channels and the anode channels. The cross-flow channel arrangement has better thermal management performance, can reduce the temperature of the fuel cell, and can also ensure sufficient contact between the anode and cathode fuels.

[0049] In addition, for the connector, it is preferred to use ferritic stainless steel material for production. Ferritic stainless steel connectors are easy to prepare and inexpensive, and are currently the best choice for connectors. It should be noted here that, under high temperature conditions, metal connectors will inevitably oxidize, forming an oxide layer on the surface. The thickness and type of the oxide layer will affect the interface compatibility between the sealing material and the connector. Existing sealing materials have poor interface compatibility with metal end plates and connector materials. Metal materials oxidize significantly at high temperatures and are only partially in contact with the sealing materials between adjacent components. The interfaces of the connectors in the solid oxide fuel cell stack provided by the present invention are tightly combined, which can effectively block the diffusion of oxygen and effectively prevent the connector from continuing to oxidize.

[0050] In actual use, the battery cell provided by the present invention is preferably one of a yttrium zirconium-based anode-supported battery, a yttrium zirconium-based electrolyte-supported battery, a scandium zirconium-based anode-supported battery, and a scandium zirconium-based electrolyte-supported single battery.

[0051] On the other hand, the present invention also provides a method for preparing a solid oxide fuel cell stack. The flow chart of the preparation method is as follows: Figure 3 As shown, the preparation method includes:

[0052] S110: clamping n cell repeating units and battery supplementing units in a clamping assembly in a stacked manner in series to form an initial battery stack;

[0053] S120: dispensing sealing material on the edges of the gas path grooves between adjacent components in the initial battery stack and then applying pressure to complete the in-situ packaging of the initial battery stack;

[0054] S130: placing the battery stack after in-situ packaging in a battery stack sintering furnace for press-fitting and sintering.

[0055] Specifically, in the process of applying pressure after dispensing the sealing material on the edges of the gas path grooves between adjacent components in the initial battery stack to complete the in-situ packaging of the initial battery stack, SiO2-CaO-Al2O3 glass-ceramic composite sealing material can be selected, and the SiO2-CaO-Al2O3 glass-ceramic composite sealing material is dispensed on the sealing path of the edges of the gas path grooves between adjacent components in the initial battery stack formed in S1, and then after applying assembly pressure perpendicular to the core assembly, the sealing material is brought into close contact with the edge of the battery to isolate the gas and air atmosphere, thereby completing the in-situ packaging of the battery stack.

[0056] Furthermore, after dispensing the sealing material on the gas path groove edge between adjacent components in the initial battery stack, pressure is applied to complete the in-situ packaging of the initial battery stack. The diameter of the dispensing pipette needle is preferably 0.5-5 mm, the air pressure is preferably 10-30 pasi, and the assembly pressure is preferably 0-300 N / section. In addition, the composite sealing material needs to have good thermal matching (for example, the thermal expansion coefficient is preferably 8.5×10 -6 / ℃-10.5×10 -6 / ℃), good insulation (conductivity is preferably less than 1×10 -8 S / cm), good adhesion (porosity is preferably less than 0.5%), good filling property (can withstand pressure of 0-1000N), and good wettability (obvious adhesion interface, element diffusion layer <20μm).

[0057] In addition, when placing the battery stack after in-situ packaging in the battery stack sintering furnace for press-fitting and sintering, after placing the battery stack after in-situ packaging in S2 in the battery stack sintering furnace, it is necessary to adjust the height of the bottom supporting bricks to avoid collision of the battery stack; after confirming the height, send the battery stack into the furnace, use a square to measure whether the pressure column is in the center of the battery stack, lower the pressure column after adjustment, and perform initial pressure with a pressure of 300-400N / section; finally, remove the 4 bolts on the top end plate and bottom end plate that fix the battery stack for press-fitting and sintering.

[0058] Furthermore, during the battery stack press assembly process, the temperature is preferably room temperature-1000°C, the press assembly pressure is preferably 300-600N / section, and the holding time is preferably 2-6 hours. During the battery stack sintering process, the binder removal temperature is preferably room temperature-800°C, the rate is preferably 0.5-2°C / min; the holding time is preferably 2-4 hours to avoid the formation of holes in the sealing material; the sealing temperature is preferably 800-1000°C, the rate is preferably 0.5-2°C / min, and the holding time is preferably 2-6 hours to avoid insufficient crystallization and softening of the sealing material or loose filling.

[0059] It should be noted that after the solid oxide fuel cell stack provided by the present invention is prepared, the gas and oxygen gas lines of the entire solid oxide fuel cell stack can be tested for air tightness using the pressure difference method and the flow method. The gas pressure is preferably 0-50 kPa, and the leakage rate needs to be <5%.

[0060] In addition, after the solid oxide fuel cell stack provided by the present invention is prepared, the battery stack power, power density, power generation efficiency and fuel utilization rate can be tested in accordance with "GB / T34582-2017 / IEC TS 62282-7-2:2014 Solid Oxide Fuel Cell and Battery Stack Performance Test Method", the temperature is set to 700-850°C, the open circuit voltage of the n-cell battery stack is n*(0.8-1.2)V, the power is n*(20-50)W, the power density is 0.2-0.5W / cm2, the power generation efficiency is 25%-50%, and the fuel utilization rate is 35%-55%.

[0061] The following is a further introduction to the method for preparing a solid oxide fuel cell stack provided by the present invention by way of examples.

[0062] Example 1

[0063] Step 1: Place the five-segment Scandium Zirconium-based anode-supported solid oxide fuel cell and components from bottom to top. Figure 1 and Figure 2 The structures shown are connected in series to form a battery stack.

[0064] Step 2: Apply glue to the sealing path of the gas channel between adjacent components in step 1. After applying assembly pressure perpendicular to the core, the sealing material is in close contact with the edge of the battery. The four corners of the stack are fixed with bolts to complete the in-situ packaging of the stack. The dispensing pipette needle has a diameter of 0.5mm, the air pressure is 20pasi, and the assembly pressure is 1500N.

[0065] Step 3: Place the battery stack encapsulated in situ in step 2 in a battery stack sintering furnace, set a pressure of 1600N for initial pressing, remove the four bolts fixing the battery stack, and press-fit sintering; battery stack pressing system: temperature is room temperature-1000℃, pressing pressure is 2000N, and holding time is 6h; battery stack sintering molding system: debinding temperature is room temperature-800℃, rate is 0.5℃ / min, and holding time is 2h; sealing temperature is 800-1000℃, rate is 1℃ / min, and holding time is 4h.

[0066] Example 2

[0067] The difference between this embodiment and embodiment 1 lies in the battery stack material. Embodiment 1 is a scandium zirconium based SOFC material (NiO-ScSZ anode / ScSZ electrolyte / GDC insulation layer / LSCF-GDC cathode), while this embodiment is a yttrium zirconium based SOFC material NiO-YSZ anode / YSZ electrolyte / GDC insulation layer / LSCF-GDC cathode. All other steps and parameters are exactly the same as those in embodiment 1. The performance test results of embodiment 1 and embodiment 2 at a medium and low temperature operating temperature of 650°C and a medium temperature operating temperature of 750°C are shown in FIG. Figure 6 .

[0068] The gas tightness test results of the battery stacks of Example 1 and Example 2 are as follows: Figure 4 As shown, the anode fuel gas path and cathode fuel gas path of the fuel cell stack were tested for air tightness using the combined pressure differential method and the flow rate method. The leakage rates of the five-cell stack under a pressure of 0-25 kPa were both less than 3%, indicating that the sealing performance of the embodiment is excellent. The fuel cell structure designed and formed by the present invention is uniform and flat, with high reliability, meeting the fuel cell stack sealing requirements and providing a guarantee for subsequent performance tests.

[0069] The open circuit voltage OCV test results of Example 1 and Example 2 are as follows: Figure 5 As shown, the OCV of the five-cell stack reaches 5.12V, which is close to the theoretical voltage. This shows that the stacks of the two embodiments are well sealed and the electrolyte of the battery is dense. The stacking process of the present invention has the advantages of simplicity, consistency and good sealing.

[0070] The electrical properties of Example 1 and Example 2 are as follows Figure 6As shown, the sealed assembly of battery stacks under different battery material conditions at medium and low temperatures of 650℃-750℃ can be achieved, and the discharge power can reach 152W.

[0071] As above Figures 1 to 6 The solid oxide fuel cell stack structure design and its preparation method according to the present invention are described by way of example. However, those skilled in the art will appreciate that various improvements may be made to the solid oxide fuel cell stack and its preparation method proposed above without departing from the scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the contents of the appended claims.

Claims

1. A solid oxide fuel cell stack, characterized in that: It comprises a clamping assembly and a core assembly clamped in the clamping assembly; wherein, The core assembly includes a battery repeating unit stacked in the clamping assembly and a spacer disposed between the battery repeating unit and the clamping assembly.

2. The solid oxide fuel cell stack according to claim 1, wherein: The clamping assembly includes a top end plate and a bottom end plate, and the isolation member includes a top isolation member and a bottom isolation member, wherein, The top separator is disposed between the battery repeating unit and the top end plate, and the bottom separator is disposed between the battery repeating unit and the bottom end plate.

3. The solid oxide fuel cell stack according to claim 2, wherein: The top isolation member includes a top mica plate, a top conductive plate, a top silver paste and silver mesh, and a top light plate, which are sequentially arranged from top to bottom; wherein the top mica plate is arranged on a side close to the top end plate, and the top light plate is arranged on a side close to the battery repeating unit; The bottom isolation member includes a bottom mica plate, a bottom conductive plate, a bottom silver paste and silver mesh, and a bottom light plate arranged in sequence from bottom to top; wherein, the bottom mica plate is arranged on a side close to the bottom end plate, and the bottom light plate is arranged on a side close to the battery repeating unit.

4. The solid oxide fuel cell stack according to claim 3, wherein: The battery repeating units are stacked n times between the top end plate and the bottom end plate; wherein n is an integer, and n≥1.

5. The solid oxide fuel cell stack according to claim 4, wherein: The battery repeating unit includes a connecting piece, a first battery piece and a first nickel mesh; wherein the connecting piece is arranged on a side of the first battery piece close to the top end plate, and the first nickel mesh is arranged on a side of the first battery piece close to the bottom end plate.

6. The solid oxide fuel cell stack according to claim 5, wherein: A battery supplement unit is arranged between the battery repeating unit in the uppermost layer and the top light panel; wherein the battery supplement unit includes a second battery cell, a second nickel mesh and a silver mesh; wherein the silver mesh is arranged on a side of the second battery cell close to the top light panel, and the second nickel mesh is arranged on a side of the second battery cell close to the battery repeating unit.

7. The solid oxide fuel cell stack according to claim 6, wherein: The connecting piece is a ferritic stainless steel connecting piece.

8. The solid oxide fuel cell stack according to claim 7, wherein: The battery cell is one of a yttrium zirconium-based anode-supported battery, a yttrium zirconium-based electrolyte-supported battery, a scandium zirconium-based anode-supported battery, and a scandium zirconium-based electrolyte-supported single battery.

9. The solid oxide fuel cell stack according to claim 8, wherein: A U-shaped gas path is provided in the core assembly, and an air inlet and an air outlet are provided on the top end plate and the bottom end plate, respectively; wherein, both ends of the U-shaped gas path are connected to the air inlet and the air outlet, respectively.

10. The method for preparing a solid oxide fuel cell stack according to any one of claims 1 to 9, wherein: The preparation method comprises: clamping n cell repeating units and battery supplementing units in the clamping assembly in a stacked manner in series to form an initial battery stack; Dispensing sealing material on the edges of gas path channels between adjacent components in the initial battery stack and then applying pressure to complete in-situ packaging of the initial battery stack; The battery stack after in-situ packaging is placed in a battery stack sintering furnace for press-fitting and sintering.

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