A solid oxide fuel cell stack structure and sealing method

Abstract

The present invention relates to the field of solid oxide fuel cell technology, and in particular to a solid oxide fuel cell stack structure and sealing method. In the technical solution of the present invention, a strategic improvement is made to the battery cell structure of the traditional stack. By adopting a reverse structure, the compression seal frame is set on the top surface of the battery cell, and the battery cell is covered with the self-gravity of the compression seal frame cleverly, thereby achieving reliable sealing between the compression seal frame and the battery cell. It overcomes the technical defect of the prior art stack structure that the gravity of the support frame itself may cause the support frame to sink due to the certain deformability of the sealant, thereby affecting the seal between the battery cell mounted on the support frame. On this basis, by further adding a compression seal component, a highly reliable seal between the compression seal frame and the battery cell is achieved. The stack structure of the invention is simple, and the sealing method is easy to implement, which greatly improves the assembly and sealing reliability of the stack and reduces the cost of the stack.

Description

Technical Field

[0001] The present invention relates to the technical field of solid oxide fuel cell assembly and sealing, and in particular to a solid oxide fuel cell stack structure and a sealing method. Background Art

[0002] Flat-plate solid oxide fuel cells offer advantages such as simple structure, easy assembly, and high power density. During stack assembly, precise dimension matching of the flat-plate cells, connecting plates, current collectors, and sealing materials is crucial, ensuring good sealing and current collection to ensure stable and efficient stack operation.

[0003] A fuel cell stack connects multiple cells through connectors and current collectors, sealed with sealing materials. This allows for multiple layers of cells to be stacked, resulting in a power output far greater than that of a single cell. A good seal ensures a regular supply of fuel and oxidant gases to the stack and prevents them from mixing. Gas leakage can cause the stack to malfunction. Furthermore, leaked fuel gas can react with air, causing localized overheating and ultimately failure. Fuel gas leaks can also pose an explosion hazard.

[0004] When sealing the stack, the sealant is in a solid state, or softened and non-flowing, requiring a certain level of pressure to achieve a seal. Excessive pressure or uneven force can affect the sealant's bond with adjacent sealing materials. Seal design is crucial to the proper and stable operation of the entire stack.

[0005] Sealing and current collection are technical difficulties in the current production of high-power solid oxide fuel cell stacks, hindering the industrialization of solid oxide fuel cells. Existing stack integration technologies include perforated cell integration and non-perforated cell integration. Perforated cell stack integration utilizes perforated individual cells, resulting in a simpler structure. However, perforation reduces the strength of the cell hole area, significantly impacting stack assembly reliability. Sealing the sides of the porous cell support also presents challenges.

[0006] The assembly of non-perforated batteries usually adopts a frame support structure, which has a complex structure, strict processing precision requirements, high cost, and the sealing between the battery and the frame is a difficult point.

[0007] The patent with announcement number CN104521053B proposes a fully sealed method for flat-plate batteries, which uses a battery frame, batteries, connecting components, sealing components, and gasket components to achieve battery sealing. Sealing components and gasket components are arranged between the battery frame and the connecting components, so as to improve the uniformity of the spacing between the battery frame and the connecting components. However, this structural design has strict requirements on materials and processing accuracy. Otherwise, the sealing layer between the battery and the support frame will not be stressed or unevenly stressed during sealing, and adaptive sealing between the two cannot be achieved, resulting in incomplete sealing between the battery and the support frame, or even falling off and separating, seriously affecting the stability and safety of the battery stack. In addition, the support frame is in contact with the sealing material, and the sealing material has a certain degree of deformability under sealing conditions. The support frame may move downward due to the gravity of the support frame itself, affecting the seal between the battery located above the support frame and the support frame, and affecting the performance of the battery stack. Summary of the Invention

[0008] The purpose of the present invention is to provide a solid oxide fuel cell stack structure and sealing method to address the technical defects of the prior art, such as the need for precise matching of the dimensions of the various components of the stack and the precise matching of the softening properties of the glass glue, which is difficult to implement and has a high risk of failure, and is not conducive to the large-scale industrialization of solid oxide fuel cells.

[0009] In order to achieve the above object, the technical solution adopted by the present invention is:

[0010] A solid oxide fuel cell stack structure comprises an upper end plate and a lower end plate arranged in parallel, and a plurality of battery cells stacked in sequence between the two end plates, a connecting plate being provided between adjacent battery cells, each of the battery cells comprising a compression sealing frame and a battery cell in sequence from top to bottom, a first sealing layer being provided between the compression sealing frame and the battery cell, a rectangular through hole being provided in the middle of the compression sealing frame, an inwardly concave rectangular step being provided on one side of the bottom of the compression sealing frame along the circumferential edge of the rectangular through hole, the rectangular step being used for compression sealing the battery cell, and the first sealing layer being provided between the battery cell and the rectangular step.

[0011] In the technical solution of the present invention, a strategic improvement is made to the battery cell structure in the traditional battery stack. In the known battery stack sealing technology, the sealing material has a light weight. During the assembly of the battery cell and the support frame, the first sealing layer provided between the two needs to be under a certain uniform pressure to achieve a good seal. The existing battery stack sealing structure generates forces acting on the support frame and the battery cell respectively by matching the dimensions of each component. A good seal can only be achieved when the dimensions and thermal properties of each component are precisely matched. Since there is glass glue on both sides of the support frame, it has a certain degree of deformability. The gravity of the support frame itself may cause the support frame to sink, thereby affecting the seal between the battery cell mounted on the frame. In the battery stack of the present invention, by adopting a reverse structure, the conventional battery support frame is flipped and placed on the battery cell to become a compression sealing frame. The compression sealing frame's own gravity is cleverly used to cover the battery cell. On this basis, by further adding a compression sealing component, a dense fit between the support frame and the battery cell is achieved, and the sealing of the battery stack is simply achieved. The battery does not require punching, and is easy to assemble, which greatly guarantees the stable performance of the battery stack.

[0012] As a preferred solution of the present invention, a pressure sealing member is provided on the top side of the pressure sealing frame in the area corresponding to the rectangular step, the pressure sealing member corresponding to the position of the first sealing layer, and the pressure sealing member is provided on the back side of the rectangular step and the adjacent area.

[0013] The pressure-sealing components are preferably four independent strip structures (pressure-sealing strips), which are respectively arranged at the four edges of the rectangular step.

[0014] Preferably, the compression sealing member may also be an annular structure, and the outline of the annular structure coincides with the outline of the rectangular step.

[0015] Further preferably, the sealing member can also be a short sheet structure (sealing sheet), which includes two to four pieces of 1-2 cm long sealing material, and the sealing sheets are respectively arranged in the middle position of the four sealing frame surfaces of the rectangular step.

[0016] Preferably, the compression seal member is made of a high-temperature-resistant, flexible material, specifically at least one of mica, glass, metal, or ceramic. This compression seal member is highly robust, ensuring adaptive matching between the compression seal frame, the cells, and the sealing material during stack sealing, achieving a large-area compression seal between layers.

[0017] The thickness of the compression sealing member is 20-1000 μm, more preferably, the thickness of the compression sealing member is 100-300 μm. The width of the compression sealing member is 1 / 3-3 times the width of the sealant, and optimally 3 / 4-3 / 2.

[0018] As a preferred solution of the present invention, the connecting plate includes a first surface and a second surface, the first surface is connected to the battery cell through a second sealing layer, and the second surface is connected to the upper surface of the compression sealing frame through a third sealing layer, where the compression sealing frame refers to the compression sealing frame of adjacent battery cells.

[0019] The first surface is provided with a first groove, and the second surface is provided with a second groove. A plurality of flow channels are respectively provided in the first groove and the second groove, and the flow channels are channels for the flow of fuel gas or air.

[0020] As a preferred embodiment of the present invention, the second sealing layer has a first through-hole in the middle, the contour of which matches the edge contour of the first groove. The third sealing layer has a second through-hole in the middle, the contour of which matches the edge contour of the second groove. The second and third sealing layers are used to seal the connecting plate, the compression seal frame, and the single cells together, achieving inter-cell sealing and isolating the fuel gas and air between the metal plates.

[0021] As a preferred solution of the present invention, a first boss group is provided in the first groove, and the first boss group is provided at the two ends of the flow channel. A second boss group is provided in the second groove, and the second boss group is also provided at the two ends of the flow channel.

[0022] On the first surface of the connecting plate, parallel to the flow channel, two flat areas are formed. Two sides of the cell correspond to the connecting plate's flat areas, while the other two sides of the cell correspond to the first set of bosses. A current collector layer is located between the connecting plate and the cell. The current collector layer, the flow channel plate's flat area, and the first set of bosses work together to provide good and uniform support for the cell.

[0023] The second boss group cooperates with the planar area of ​​the connecting plate parallel to the flow channel to jointly apply pressure to the pressure sealing component, acting on the first sealing layer to achieve good sealing.

[0024] Preferably, a current collecting layer is further provided at the first surface position where the connector contacts the battery cell. The current collecting layer is a well-known flexible porous metal material, which may be one or more of silver mesh, nickel mesh, and stainless steel mesh.

[0025] As a preferred embodiment of the present invention, the first boss group includes a plurality of first boss units, and the plurality of first boss units are used to support the edges of the battery cell. The second boss group includes a plurality of second boss units, and the plurality of second boss units are used to abut the upper surface of the pressure sealing frame. The plurality of first boss units are used to disperse the reaction gas, and at the same time cooperate with the side plane area parallel to the flow channel of the first surface of the collecting net and the connecting plate to support the sealing edges around the battery cell. The second boss group includes a plurality of second boss units, and the plurality of second boss units are used to disperse the reaction gas, and at the same time cooperate with the side plane area parallel to the flow channel of the second surface of the connecting plate to abut the pressure sealing component, thereby applying pressure to the pressure sealing frame.

[0026] The connecting plate allows for the inflow and outflow of gas, either fuel gas or air, and distribution through through-holes and flow channels. For example, if fuel gas enters the flow channel through a through-hole on one side of the first groove, air enters the flow channel through a through-hole on the opposite side of the second groove. Fuel gas and air flow in the same or opposite directions on either side of the connecting plate. Cross-flow of fuel gas and air can also be achieved by partially adjusting the connecting plate structure.

[0027] Specifically, the first boss group is arranged on the side close to the battery cell, and the second boss group is arranged on the side of the compression seal frame close to the adjacent battery stack unit. The first boss unit is used to support the edge of the battery cell to ensure that when the sealing material is sealed with the battery at the rectangular step of the compression seal frame, the battery cell will not bend due to the downward force and fail to form a compression seal, thereby avoiding the battery stability being reduced due to the insufficient bonding of the sealing material. The side plane area parallel to the flow channel on the first surface of the connecting plate cooperates to support the sealing edge of the battery cell, while the side plane area parallel to the flow channel on the second surface of the connecting plate cooperates to support the compression seal component and apply pressure to the compression seal frame.

[0028] As a preferred embodiment of the present invention, the first sealing layer is at least one of glass, ceramic, and well-known composite sealing materials and brazing materials; the second sealing layer is at least one of glass, ceramic, and well-known composite sealing materials and brazing materials; the third sealing layer is at least one of glass, ceramic, and well-known composite sealing materials and brazing materials.

[0029] Preferably, the thickness of the third sealing layer is not less than the thickness of the pressure-sealing component.

[0030] Preferably, the heat shrinkage rate of the sealing materials in the first sealing layer, the second sealing layer and the third sealing layer is 5%-80%. More preferably, the heat shrinkage rate of the multi-layer sealing material is 30%-50%.

[0031] Preferably, the thickness of the compression sealing member is thinner than that of the sealing material, so that sufficient contact between layers can be more finely adjusted.

[0032] Preferably, the sealing material can be prepared into an independent sealing layer by casting, or prepared by screen printing, casting, or dispensing to form an integrated structure with the sealing surface.

[0033] Further preferably, a support member is provided on the lower surface of the compression seal frame, and at least one of the support member and the compression seal member is made of an insulating material. When the cathode of the battery cell faces upward, the compression seal member is made of an insulating material, and the support member can be either an insulating material or a non-insulating material. When the anode of the battery cell faces upward, the compression seal member can be either an insulating material or a conductive material, and the support member is made of an insulating material.

[0034] The support member corresponds to the position of the first sealing layer and the pressure-sealing member, and is located on both sides of the pressure-sealing frame with the pressure-sealing member.

[0035] The supporting members are preferably four independent strip structures (sealing strips), which are respectively arranged at the four sealing edges of the battery cell.

[0036] Preferably, the supporting member may also be an annular structure, and the outline of the annular structure coincides with the outline of the rectangular step or the first sealing layer.

[0037] Further preferably, the support member can also be a sheet structure (sealing sheet), which includes 2-4 pieces of support material with a length of 1-2 cm. The support sheets are respectively arranged on the battery sheet and correspond to the middle areas of the four sides on the back of the first sealing layer.

[0038] Preferably, the support member is made of a high-temperature resistant flexible material, specifically at least one of mica, glass, metal or ceramic materials.

[0039] Preferably, the connector and the compression sealing frame can be made of a known metal material for solid oxide fuel cells, preferably ferritic stainless steel.

[0040] A method for sealing a solid oxide fuel cell stack comprises the following steps:

[0041] S1. Stacking a plurality of battery cells and a plurality of connecting plates in the above-mentioned battery stack structure between an upper end plate (101) and a lower end plate (102) arranged in parallel in the order of ABABAB...A to form a first battery stack, wherein A represents a battery cell and B represents a connecting plate; specifically, the battery cells are pre-assembled first, a second sealing layer is provided on the first surface of the connecting plate, and a third sealing layer is provided on the second surface of the connecting plate, and then a prescribed number of stacking steps are repeated in the above manner;

[0042] Alternatively, one of the battery cells and one of the connecting plates in the above-mentioned stack structure is regarded as a stack unit, and then the stack unit is stacked in sequence between the upper end plate and the lower end plate arranged in parallel to form a second stack; specifically, the stack unit is pre-assembled and then the stack units are stacked;

[0043] Alternatively, the battery cell, the first sealing layer, the compression sealing frame, the third sealing layer, the connecting plate, and the second sealing layer are stacked sequentially from bottom to top in the order of EFGCHD-EFGCHD...G between the upper end plate (101) and the lower end plate (102) arranged in parallel to form a third battery stack; wherein E represents the battery cell, F represents the first sealing layer, G represents the compression sealing frame, H represents the connecting plate, C represents the third sealing layer, and D represents the second sealing layer;

[0044] S2. Move the first battery stack, or the second battery stack, or the third battery stack into a high-temperature furnace for high-temperature firing to complete the sealing of the battery stack.

[0045] Preferably, in step S1, the assembly process of the first battery stack, the second battery stack, and the third battery stack all involves the assembly of the first sealing layer, the second sealing layer, and the third sealing layer. The sealing layer can be prepared as an independent sealing layer by casting; or prepared by screen printing, casting, or dispensing to form an integrated structure with the sealing surface;

[0046] More preferably, according to the assembly method of S1 above, the corresponding positions during the assembly process also include installing a compression sealing member and / or installing a supporting member.

[0047] In the sealing method of the present invention, during the firing process, the solid oxide fuel cell stack is fired in a high-temperature furnace in a stacked form with the compression sealing frame on top and the battery cells on the bottom, so that each layer in the final stack can form a better sealing effect.

[0048] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0049] The battery stack of the present invention has a simple structure, is easy to assemble, and offers stable performance. This is achieved by strategically improving the structure of the battery cells in conventional battery stacks. Specifically, a compression seal frame is placed inverted on top of the battery cells, allowing the weight of the compression seal frame to act on the battery cells, securing them tightly. Furthermore, by adding compression seal components, a close fit between the compression seal frame and the battery cells is achieved, simplifying the sealing of the battery stack. This reduces assembly difficulty, improves sealing reliability, and significantly ensures the stable performance of the battery stack.

[0050] Through the innovative use of sealing components, the thickness of the sealing strip is thinner than the sealing material, which can be used to fine-tune the downward movement distance of the sealing frame to achieve adaptive matching between layers.

[0051] The technical solution of the present invention provides a sealing method for a solid oxide fuel cell stack, in which the stack is installed in reverse and placed in a high-temperature furnace for firing, so that the finally sealed stack has high sealing efficiency, high sealing reliability, and the stack operation remains stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 It is a schematic structural diagram of the battery stack of the present invention;

[0053] Figure 2 It is a structural schematic diagram of the battery stack unit of the present invention;

[0054] Figure 3 1 is a schematic side view of the structure of the battery stack of the present invention;

[0055] Figure 4 1 is a schematic side view of the structure of the battery stack unit of the present invention;

[0056] Icons: 101-upper end plate; 102-lower end plate; 103-sealing frame; 104-connecting plate; 105-battery cell; 107-sealing strip; 1061-first sealing layer; 1062-second sealing layer; 1063-third sealing layer; 1001-battery cell; 1002-stack cell; 2-rectangular through hole; 3-rectangular step; 1041-flow channel; 1043-first boss group; 1044-second boss group; 5-third boss; 6-fourth boss, 7-first through hole; 8-second through hole. DETAILED DESCRIPTION

[0057] The present invention will be described in detail below with reference to the accompanying drawings.

[0058] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0059] Example 1

[0060] This embodiment discloses a solid oxide fuel cell stack, such as Figure 1-4 As shown, it includes an upper end plate 101 and a lower end plate 102 arranged in parallel, and a plurality of battery cells 1001 stacked in sequence arranged between the two end plates, and a connecting plate 104 is provided between adjacent battery cells 1001;

[0061] Specifically, each of the battery cells 1001 includes a compression seal frame 103 and a battery cell 105 from top to bottom. A first sealing layer 1061 is provided between the compression seal frame 103 and the battery cell 105. A rectangular through-hole 2 is provided in the middle of the compression seal frame 103. A concave rectangular step 3 is provided on one side of the bottom of the compression seal frame 103 along the circumferential edge of the rectangular through-hole 2. The rectangular step 3 is used to fix the battery cell 105. The first sealing layer 1061 is provided between the battery cell 105 and the rectangular step 3. The depth of the concave rectangular step 3 is adapted to the thickness of the battery cell 105. The battery's dense electrolyte side is sealed with the step through the first sealing layer 1061. The sealing requires applying a stable and continuous balanced pressure to the first sealing layer 1061. The first sealing layer 1061 is at least one of glass, ceramic, a well-known composite sealing material, and a silver-based brazing material.

[0062] To ensure the long-term stability of the seal, a sealing assembly method is designed with the compression seal frame 103 on top and the battery cell 105 on the bottom. The compression seal frame 103 is usually made of ferritic stainless steel and uses its own gravity to achieve free cooperation with the battery cell 105 and compress the battery.

[0063] The back of the rectangular step 3 is provided with a pressure-sealing member. In this embodiment, the pressure-sealing member is in the form of a pressure-sealing strip 107, which is positioned corresponding to the first sealing layer 1061. The pressure-sealing strip 107 is made of a high-temperature resistant flexible material, specifically at least one of mica, glass, metal, or ceramic. In this embodiment, four mica strips (pressure-sealing strips 107) are provided on the back of the step of the pressure-sealing frame 103, each with a thickness of 500 μm.

[0064] The connecting plate 104 includes a first surface and a second surface. The first surface is connected to the battery cells 105 and the lower surface of the compression seal frame via a second sealing layer 1062. The second surface is connected to the upper surface of the adjacent compression seal frame 103 and the battery cells 105 via a third sealing layer 1063. The thickness of the third sealing layer is greater than that of the compression seal strip. The thermal shrinkage rate of the sealing materials used in the first, second, and third sealing layers ranges from 5% to 80%.

[0065] The first surface of the connecting plate is provided with a first groove, and the second surface is provided with a second groove. The first groove and the second groove are respectively provided with a plurality of flow channels 1041, which are passages for the flow of fuel gas or air. The second sealing layer 1062 and the third sealing layer 1063 are made of high-temperature glass.

[0066] The lower surface of the connecting plate 104 is designed with a protruding flow channel 1041 that matches the step height of the pressure sealing frame 103. The height of the flow channel 1041 is convenient for current collection with the battery cathode. There is a silver current collecting net between the cathode and the connecting plate. The upper surface of the connecting plate 104 is designed as a planar flow channel 1041, which cooperates with the anode of the adjacent battery cell 105 for current collection.

[0067] The second sealing layer 1062 has a first through hole 7 in the middle, and the contour of the first through hole 7 matches the edge contour of the first groove. The third sealing layer 1063 has a second through hole 8 in the middle, and the contour of the second through hole matches the edge contour of the second groove.

[0068] A first boss group 1043 is provided in the first groove and is disposed at both ends of the flow channel 1041 . A second boss group 1044 is provided in the second groove and is also disposed at both ends of the flow channel.

[0069] The first boss group 1043 includes several first boss units, and several first boss units are used to disperse the fuel gas. A third boss 5 is provided on the first surface of the connecting plate 104, and the third boss 5 is provided at the opposite end of the first boss unit. The first boss unit and the third boss 5 are respectively located at the two ends of the flow channel, and the third boss 5 is flush with the first surface. The first boss group 1043, the third boss 5 can cooperate with the side plane area parallel to the flow channel 1041 on the first surface of the connecting plate 104 to support the sealing edges around the battery cell 105.

[0070] The second boss group 1044 includes several second boss units, and several second boss units are used to disperse air. A fourth boss 6 is provided on the second surface of the connecting plate 104, and the fourth boss 6 is provided at the opposite end of the second boss group 1044. The second boss group 1044 and the fourth boss 6 are respectively located at the two ends of the flow channel, and the fourth boss 6 is flush with the second surface. The second boss group 1044, the fourth boss 6 and the side plane area parallel to the flow channel 1041 on the second surface of the connecting plate 104 cooperate to support the pressure sealing strip 107 and apply pressure to the pressure sealing frame 103.

[0071] The connecting plate allows for the inflow, outflow, and distribution of gas, where the gas refers to either fuel gas or air, through through-holes and flow channels 1041. In this embodiment, fuel gas enters flow channel 1041 through a through-hole on one side of the first groove, while air enters flow channel 1041 through a through-hole on the opposite side of the second groove. The fuel gas and air flow in opposite directions on either side of the connecting plate 104.

[0072] The second sealing layer 1062, compression seal 107, compression seal frame 103, first sealing layer 1061, and battery cell 105 form a complete battery cell 1001. The third sealing layer 1063 then seals the battery cell 1001 and the connecting plate 104 together to form a stack unit 1002. After the stack units 1002 are stacked, upper and lower end plates 101 and 102 are installed at both ends to form a stack. The connecting plate 104 is not installed in the stack unit 1002 near the lower end plate 102.

[0073] In the present invention, there are two ways to attach the battery cells to the compression seal frame: either on the cathode side or the anode side. In this embodiment, the compression seal frame contacts the battery cells on the cathode side. To facilitate performance comparison of different stack structures, the following embodiments and comparative examples uniformly utilize the compression seal frame connected to the cathode side battery cells.

[0074] Example 2

[0075] This embodiment 2 discloses a solid oxide fuel cell stack, whose structure is basically the same as the stack structure in embodiment 1, with the difference that two mica strips with a thickness of 400 μm are provided on the back of the rectangular step of the pressure sealing frame 103 to ensure electrical insulation between the pressure sealing frame 103 and the connecting plate 104.

[0076] Example 3

[0077] This embodiment 3 discloses a solid oxide fuel cell stack, the structure of which is basically the same as that of the stack in embodiment 1, except that no pressure-sealing component is provided on the back of the rectangular step of the pressure-sealing frame 103 .

[0078] Example 4

[0079] This embodiment 4 provides a method for sealing a solid oxide fuel cell stack, specifically comprising the following steps:

[0080] S1: In step S1, the battery stack structures of embodiments 1-3 are assembled respectively according to the stacking method of the first battery stack; specifically, the first battery stack is stacked according to the following method:

[0081] The battery cells, the first sealing layer, and the compression sealing frame are pre-assembled into a battery unit (1001); a plurality of battery units (1001), a second sealing layer (1062), a plurality of connecting plates (104), and a third sealing layer (1063) are stacked between an upper end plate (101) and a lower end plate (102) arranged in parallel in the order of ABCD-ABCD...A to form a first battery stack; wherein A represents a battery unit, B represents a second sealing layer, C represents a connecting plate, and D represents a third sealing layer; specifically, the first sealing layer, the second sealing layer, and the third sealing layer can be prepared as independent sealing layers by casting; or can be prepared by screen printing, casting, or dispensing to form an integrated structure with the sealing surface;

[0082] S2: The stack structures of the above-mentioned embodiments 1-3 are respectively moved into a high-temperature furnace for firing to complete the sealing of the stack.

[0083] Example 5

[0084] This embodiment 5 provides a method for sealing a solid oxide fuel cell stack, specifically comprising the following steps:

[0085] S1: In step S1, the stack structures of Examples 1-3 are assembled respectively according to the stacking method of the third stack; specifically, the second stack is assembled according to the following method:

[0086] The battery cell, the first sealing layer, the compression sealing frame, the third sealing layer, the connecting plate, and the second sealing layer are sequentially stacked from bottom to top in the order of EFGCHD-EFGCHD...G between the upper end plate (101) and the lower end plate (102) arranged in parallel to form a third battery stack; wherein E represents the battery cell, F represents the first sealing layer, G represents the compression sealing frame, H represents the connecting plate, C represents the third sealing layer, and D represents the second sealing layer;

[0087] S2: The stack structures of the above-mentioned embodiments 1-3 are respectively moved into a high-temperature furnace for firing to complete the sealing of the stack.

[0088] Comparative Example 1

[0089] This comparative example 1 discloses a solid oxide fuel cell stack, the structure of which is basically the same as that of the stack in Example 1, except that: a sealing assembly method is adopted in which the compression sealing frame 103 is flipped over and the cell sheet 105 is placed on top, and an annular mica is provided on the cell sheet 105.

[0090] Comparative Example 2

[0091] Comparative Example 2 discloses a solid oxide fuel cell stack, the structure of which is substantially the same as that of the stack in Comparative Example 1, with the difference that two mica strips are provided on the back of the rectangular step of the compression sealing frame 103 .

[0092] Comparative Example 3

[0093] Comparative Example 3 discloses a solid oxide fuel cell stack, the structure of which is basically the same as that of the stack in Comparative Example 1, except that no mica strips or ring-shaped mica are added.

[0094] The battery stack structures of Examples 1-3 and the battery cells in Comparative Examples 1-3 completed according to the sealing method of Example 4 were respectively assembled into battery stacks containing 50 battery cells for stack testing. The battery stacks were subjected to leak detection and battery stack reduction tests. The leak detection and OCV test results are shown in Table 1.

[0095] Table 1 is a summary of the leakage and COV test results of the fuel cell stack

[0096] Example Leak detection OCV Example 1 No leakage 56.25V Example 2 No leakage 55.90V Example 3 Basically no leakage 55.40V Comparative Example 1 Slight air leak 53.85 Comparative Example 2 Slight air leak 52.15 Comparative Example 3 Serious air leakage -

[0097] By making structural changes to the battery cells and adopting a reverse structure, the conventional battery support frame is flipped and placed on the battery cells to form a compression sealing frame. The battery cells are cleverly covered with the compression sealing frame's own gravity, thereby achieving tight assembly. On this basis, by further adding compression sealing components, a close fit between the compression sealing frame and the battery cells is achieved, making the assembly process of the entire battery stack simpler. After sealing according to any one of the battery stack structures in Examples 1-3, it is quick and can achieve better battery performance.

[0098] The results show that the sealing method of the present invention of reversely assembling the battery stack and high-temperature firing has significant benefits in improving the assembly and sealing reliability of the battery stack.

[0099] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for sealing a solid oxide fuel cell stack, characterized in that: The steps include: S1. Stacking a plurality of battery cells (1001) and a plurality of connecting plates (104) in a battery stack structure between an upper end plate (101) and a lower end plate (102) arranged in parallel in the order of ABABAB...A to form a first battery stack, wherein A represents a battery cell and B represents a connecting plate; Alternatively, one of the battery cells and one of the connecting plates is regarded as a stack unit (1002), and the stack unit (1002) is then stacked in sequence between the upper end plate (101) and the lower end plate (102) arranged in parallel to form a second stack; Alternatively, the battery cell, the first sealing layer, the compression sealing frame, and the connecting plate are stacked in sequence between the upper end plate (101) and the lower end plate (102) arranged in parallel in the order of EFGHEFGH...G to form a third battery stack; wherein E represents the battery cell, F represents the first sealing layer, G represents the compression sealing frame, and H represents the connecting plate; S2. Move the first battery stack, the second battery stack, or the third battery stack in step S1 into a high-temperature furnace for firing to complete the sealing of the battery stack; The battery stack structure comprises an upper end plate (101) and a lower end plate (102) arranged in parallel, and a plurality of battery cells (1001) arranged in sequence and stacked between the two end plates, and a connecting plate (104) is arranged between adjacent battery cells (1001). The battery stack structure is characterized in that each of the battery cells (1001) comprises a compression sealing frame (103) and a battery cell (105) in sequence from top to bottom, a first sealing layer (1061) is arranged between the compression sealing frame (103) and the battery cell (105), a rectangular through hole (2) is arranged in the middle of the compression sealing frame (103), and a concave rectangular step (3) is arranged on one side of the bottom of the compression sealing frame (103) along the circumferential edge of the rectangular through hole (2), the rectangular step (3) is used to compress the battery cell (105), and the first sealing layer (1061) is arranged between the battery cell (105) and the rectangular step (3).

2. The method for sealing a solid oxide fuel cell stack according to claim 1, wherein: On one side of the top of the compression-sealing frame (103), a compression-sealing component is provided in an area corresponding to the rectangular step (3), and the compression-sealing component corresponds to the position of the first sealing layer (1061).

3. The method for sealing a solid oxide fuel cell stack according to claim 2, wherein: The compression sealing member is made of at least one of mica, glass, metal or ceramic materials.

4. The method for sealing a solid oxide fuel cell stack according to claim 2, wherein: The connecting plate (104) includes a first surface and a second surface, wherein the first surface is connected to the lower surface of the compression sealing frame (103) via a second sealing layer (1062), and the second surface is connected to the upper surface of the compression sealing frame (103) of the adjacent battery cell (1001) via a third sealing layer (1063), the first surface is provided with a first groove, and the second surface is provided with a second groove, and a plurality of flow channels (1041) are respectively provided in the first groove and the second groove, and the flow channels (1041) are channels for the flow of fuel gas or air.

5. The method for sealing a solid oxide fuel cell stack according to claim 4, wherein: The second sealing layer (1062) has a first through hole (7) in the middle, and the outline of the first through hole (7) matches the edge outline of the first groove. The third sealing layer (1063) has a second through hole (8) in the middle, and the outline of the second through hole (8) matches the edge outline of the second groove.

6. The method for sealing a solid oxide fuel cell stack according to claim 4, wherein: A first boss group (1043) is provided in the first groove, and the first boss group (1043) is provided at both ends of the flow channel (1041); a second boss group (1044) is provided in the second groove, and the second boss group (1044) is provided at both ends of the flow channel.

7. The method for sealing a solid oxide fuel cell stack according to claim 6, wherein: The first boss group (1043) includes a plurality of first boss units, and the plurality of first boss units correspond to the edges of the battery cell (105); the second boss group (1044) includes a plurality of second boss units, and the plurality of second boss units correspond to the upper surface of the compression sealing frame (103).

8. The method for sealing a solid oxide fuel cell stack according to any one of claims 4 to 7, characterized in that: The first sealing layer (1061) is at least one of glass, ceramics and composite sealing materials thereof, and brazing materials; The second sealing layer (1062) is at least one of glass, ceramics and composite sealing materials thereof, and brazing materials; The third sealing layer (1063) is at least one of glass, ceramics and composite sealing materials thereof, and brazing materials.

9. The method for sealing a solid oxide fuel cell stack according to claim 8, wherein: The thickness of the third sealing layer (1063) is not less than the thickness of the pressure-sealing member.

10. The method for sealing a solid oxide fuel cell stack according to claim 9, wherein: A supporting member is provided on the lower surface of the compression sealing frame (103), and at least one of the supporting member and the compression sealing member is made of insulating material.

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