A battery stack sealing structure and battery stack

Abstract

This invention provides a battery stack sealing structure and a battery stack. The battery stack sealing structure includes a first metal electrode plate, a second metal electrode plate, and a sealing element. The sealing element is disposed between the first metal electrode plate and the second metal electrode plate. The sealing element includes a first adhesive layer, an elastic layer, and a second adhesive layer stacked together. The first metal electrode plate has a first elastic groove protruding towards the sealing element, and the second metal electrode plate has a second elastic groove protruding towards the sealing element. The first adhesive layer is bonded to the top surface of the first elastic groove, and the second adhesive layer is bonded to the top surface of the second elastic groove. The sealing structure of this invention can ensure that each metal electrode plate of the stacked single cell is subjected to uniform force, avoid gaps between the metal electrode plates of adjacent single cells, and reduce the pressure required for battery stack assembly.

Description

Technical Field

[0001] This invention relates to the field of electrochemical battery technology, and more specifically, to a battery stack sealing structure and a battery stack. Background Technology

[0002] Metal plates are important components in electrochemical batteries such as fuel cells and flow batteries. A battery stack consists of multiple individual cells, each of which is assembled from a membrane electrode assembly and metal cathode and anode plates on both sides. During stack assembly, multiple individual cells need to be stacked, and the cathode and anode plates of adjacent individual cells need to be sealed to ensure that the fluid flows within the designed flow field and prevents internal or external leakage.

[0003] In existing technology, the sealing method for the metal plates of adjacent single cells adopts a pressure-type sealing structure. Its structure is as follows: Figure 1 As shown, a groove 12 is provided on the first metal plate 1 of a single cell, and a sealing strip 5 is installed in the groove. During battery assembly, an external force is applied to cause the second metal plate 2 of the adjacent single cell to press against the sealing strip 5, causing the sealing strip 5 to deform. After sealing, there is a large contact force between the sealing strip 5 and the metal plates on both sides, thereby achieving a compression seal. However, to ensure the sealing effect, this structure requires a large pressure to be applied to the metal plates, which leads to the following problems:

[0004] (1) Impact on battery performance: During battery stack assembly, hundreds of individual cells are stacked together, making it impossible to ensure that each metal plate of each individual cell is subjected to the same force. Metal plates at different assembly positions will inevitably have pressure differences. At the same time, in order to ensure the sealing effect, it is necessary to apply a standard pressure to the metal plate with the least pressure. At this time, other metal plates will be subjected to pressure exceeding the standard. Since the metal plates themselves are very thin, the metal plates subjected to excessive pressure will deform, causing the flow channels on the metal plates to deform and compress, reducing the fluid flow of the individual cell and degrading its performance.

[0005] (2) Affecting battery life: The metal plates and sealing strips of the pressure-sealed structure form a structure similar to a simply supported beam, which can lead to local stress concentration and easily cause deformation and damage to the metal plates. In addition, due to the existence of assembly tolerances, there may be gaps between some metal plates and sealing strips, allowing water to enter the flow field and corrode the metal plates, resulting in a shortened battery life.

[0006] (3) High production cost: The pressure sealing structure must ensure that the sealing strip and the metal plate have a large compressive force. Correspondingly, a large assembly force must be applied during assembly, so special pressure sealing equipment is required, which increases the equipment cost. In addition, the sealing strip has to withstand a large pressure, which makes the material selection more demanding and the material cost high. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the purpose of this invention is to provide a new fuel cell stack sealing structure that ensures uniform stress on each stacked metal plate, avoids gaps between metal plates of adjacent single cells, and reduces the pressure required for fuel cell stack assembly.

[0008] To achieve the above objectives, the present invention provides a fuel cell stack sealing structure, comprising a first metal electrode plate, a second metal electrode plate, and a sealing element. The first metal electrode plate is the cathode / anode plate of a single cell, and the second metal electrode plate is the anode / cathode plate of another adjacent single cell. The sealing element is disposed between the first metal electrode plate and the second metal electrode plate. The sealing element includes a first adhesive layer, an elastic layer, and a second adhesive layer stacked together. The first metal electrode plate has a first elastic groove protruding toward the sealing element, and the second metal electrode plate has a second elastic groove protruding toward the sealing element. The first adhesive layer is bonded to the top surface of the first elastic groove, and the second adhesive layer is bonded to the top surface of the second elastic groove.

[0009] This invention utilizes the elastic grooves on the metal plates on both sides and the elastic layer of the sealant to absorb pressure. The elastic grooves and elastic layer have a pressure regulating effect, ensuring that the stacked metal plates are subjected to uniform force, preventing deformation of the metal plates, and guaranteeing consistent performance of each individual cell. The sealant is bonded to the elastic grooves on both sides of the metal plates. Even with assembly tolerances, the adhesion between the adhesive layer and the metal plates can prevent gaps between the sealant and the metal plates, ensuring a good sealing effect. This sealing structure achieves a seal by bonding the adhesive layer and the surface of the elastic grooves, requiring no large pressure to achieve a good sealing effect. Therefore, the assembly force required is small, which helps reduce equipment and material costs. Furthermore, it is easy to assemble and disassemble, and the individual cells can be reassembled.

[0010] Preferably, the first and second adhesive layers are made of pressure-sensitive adhesive, and the elastic layer is made of rubber. The seal adopts a sandwich structure, where the adhesive layer bonds with the elastic groove under relatively small pressure, eliminating gaps between adjacent metal plates and achieving a good sealing effect. The assembly pressure is mainly absorbed by the elastic groove, and when excessive pressure is generated, the elastic layer deforms to absorb the excess pressure, preventing damage to the metal plates.

[0011] Preferably, the thickness of the elastic layer is between 300 and 600 μm. A certain thickness of the elastic layer can compensate for assembly tolerances and ensure contact between the adhesive layer and the elastic groove; however, the thickness of the elastic layer should not be too large to avoid localized stress concentration.

[0012] Preferably, the projection of the seal on the first metal electrode plate covers the first elastic groove, and the projection of the seal on the second metal electrode plate covers the second elastic groove. The seal covers areas where gaps may occur, while simultaneously increasing the contact area with the elastic grooves on both sides, dispersing pressure, and preventing stress concentration.

[0013] Preferably, the cross-sections of the first and second elastic grooves are isosceles trapezoids with an upper base angle ranging from 120° to 160°. The isosceles trapezoidal structure ensures that the elastic grooves have good structural strength and elasticity, and can automatically adjust the pressure.

[0014] Preferably, the width of the top surface of the first elastic groove is between 1 and 2 mm, the width of the inclined surface of the first elastic groove is between 0.4 and 0.6 mm, the width of the top surface of the second elastic groove is between 1 and 2 mm, and the width of the inclined surface of the second elastic groove is between 0.4 and 0.6 mm. Limiting the width and inclination angle of the elastic grooves controls the protrusion height, thereby ensuring that the flow channel dimensions are within the design range. Furthermore, controlling the width of the top surface and the width of the inclined surface in a suitable ratio ensures that pressure can be transmitted to the inclined surface when the top surface is subjected to force, and the pressure can be adjusted through elastic deformation.

[0015] Preferably, the seal has an overlapping area that simultaneously contacts the top surface of both the first and second elastic grooves. The overlapping area is the portion where the two elastic grooves overlap and cover the seal; in this portion, the two elastic grooves and the seal work together to absorb pressure.

[0016] Preferably, the width of the overlapping area is greater than or equal to 0.5 mm. In the design of the fuel cell stack sealing structure, the overlapping area of ​​the elastic protrusions on both sides covering the seal is made as large as possible. Due to assembly tolerances, the relative positions of the elastic protrusions on both sides may shift during assembly, but this sealing structure can absorb larger assembly tolerances. As long as the width of the overlapping area is not too small, the sealing effect can be guaranteed.

[0017] Preferably, the width of the top surface of the first elastic groove is greater than the width of the top surface of the second elastic groove, and the wall thickness of the first elastic groove is greater than the wall thickness of the second elastic groove. This allows the deformation of the second elastic groove to be greater than that of the first elastic groove, ensuring a consistent sealing structure between each individual cell under stress and eliminating the influence of assembly tolerances.

[0018] The present invention also provides a battery stack, including the above-described stack sealing structure.

[0019] In summary, compared with the prior art, the present invention has the following beneficial effects:

[0020] (1) The pressure is adjusted by the sealing element and the elastic grooves on both sides of the stack, so that the stacked metal plates are subjected to uniform force and no metal plate is subjected to excessive force, thereby ensuring the stability of the flow channel size between the metal plates and the uniform performance of each cell.

[0021] (2) The seal fits into the elastic groove, with a large contact area, so there will be no local stress concentration, thus avoiding damage to the metal plate.

[0022] (3) The seal is bonded to the metal plates on both sides, which can prevent gaps between the seal and the metal plates, ensure the sealing effect, and help extend the battery life.

[0023] (4) The seal is achieved by bonding the seal to the metal plate, which greatly reduces the pressure required during assembly, reduces the cost of assembly equipment and sealing materials, and makes disassembly and assembly convenient.

[0024] (5) Due to the low assembly pressure and small deformation of the seal, the single cell in the stack can be disassembled and reassembled, and the sealing performance can still be guaranteed. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the cross-sectional structure of a conventional fuel cell stack sealing structure.

[0026] Figure 2 This is a schematic cross-sectional view of the fuel cell stack sealing structure in an embodiment of the present invention.

[0027] Figure 3 This is a schematic diagram of the cross-sectional structure of the seal in an embodiment of the present invention.

[0028] Figure 4 This is a diagram showing the cross-sectional dimensions of the fuel cell stack sealing structure in an embodiment of the present invention.

[0029] Figure 5 This is a schematic diagram of the cross-sectional structure of the fuel cell stack seal in another embodiment of the present invention.

[0030] Explanation of reference numerals in the attached figures:

[0031] 1-First metal electrode plate, 11-First elastic groove, 12-Groove, 2-Second metal electrode plate, 21-Second elastic groove, 3-Sealing element, 31-First adhesive layer, 32-Elastic layer, 33-Second adhesive layer, 34-Overlapping area, 4-Membrane electrode, 5-Sealing strip. Detailed Implementation

[0032] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that the following embodiments are only used to illustrate the implementation methods and typical parameters of the present invention, and are not intended to limit the parameter range described in the present invention. Reasonable variations derived therefrom are still within the protection scope of the claims of the present invention.

[0033] The battery stack is the core component of an electrochemical battery, consisting of multiple stacked individual cells and current collectors. Each individual cell comprises a membrane electrode 4 and a first metal plate 1 (cathode / anode plate) and a second metal plate 2 (anode / cathode plate) disposed on both sides of the membrane electrode 4. After multiple individual cells are stacked, the first metal plate 1 of one individual cell is sealed to the second metal plate 2 of the adjacent individual cell. The sealing structure is generally located at the edge of the metal plate body and the edge of the three-cavity opening. A coolant flow field is formed between adjacent first metal plates 1 and second metal plates 2.

[0034] Combination Figures 2 to 5 As shown, this embodiment provides a sealing structure for sealing adjacent single batteries, including a sealing element 3 disposed between a first metal electrode plate 1 and a second metal electrode plate 2, a first elastic groove 11 protruding from the first metal electrode plate 1 toward the sealing element 3, and a second elastic groove 21 protruding from the second metal electrode plate 2 toward the sealing element 3. The first elastic groove 11 / second elastic groove 21 are integrally formed with the first metal electrode plate 1 / second metal electrode plate 2, generally formed by a stamping process, and have a certain elasticity. After being subjected to force, they will undergo elastic deformation, thereby absorbing the pressure on the metal electrode plates and automatically adjusting to make the force on each metal electrode plate uniform.

[0035] Combination Figure 3 As shown, the sealing element 3 includes a first adhesive layer 31, an elastic layer 32, and a second adhesive layer 33 stacked together. The first adhesive layer 31 is bonded to the top surface of the first elastic groove 11, and the second adhesive layer 33 is bonded to the top surface of the second elastic groove 21. This sealing structure achieves sealing by bonding the adhesive layer and the surface of the elastic groove. It can achieve a good sealing effect without applying a lot of pressure, and the adhesive force can eliminate the influence of assembly tolerance on the sealing performance, ensuring that there are no gaps between the sealing element 3 and the metal electrode plate.

[0036] The elastic layer 32 in the seal 3 is made of an elastic material, preferably rubber. This material can absorb excessive pressure through deformation to prevent damage to the metal plates without excessive compression. After the pressure is removed, the elastic layer 32 can partially recover its deformation, ensuring sealing performance even after disassembling and reassembling the individual cells in the fuel cell stack. The first adhesive layer 31 and the second adhesive layer 33 are made of adhesive materials, preferably pressure-sensitive adhesive. They adhere to the top surface of the elastic groove after being subjected to assembly pressure.

[0037] Combination Figure 2and Figure 4 As shown, in this embodiment, the sealing element 3 has a large width, covering the area where gaps may occur. Its projection on the first metal plate 1 covers the first elastic groove 11, and its projection on the second metal plate 2 covers the second elastic groove 21, ensuring that the top surfaces of the elastic grooves on both sides are in complete contact with the sealing element 3. The contact surface is large enough to ensure the sealing effect and avoid stress concentration.

[0038] In this embodiment, the cross-sections of the first elastic groove 11 and the second elastic groove 21 are isosceles trapezoids with an upper base angle of 145°. This structure gives the elastic grooves excellent structural strength and elasticity, thereby supporting and absorbing assembly pressure. In some optional embodiments, the cross-sections of the first elastic groove 11 and the second elastic groove 21 are isosceles trapezoids with an upper base angle ranging from 120° to 160°.

[0039] In other embodiments, the cross-section of the first elastic groove 11 and the second elastic groove 21 is a double-layer isosceles trapezoid. This structure has better elasticity, but with the overall width of the elastic groove remaining unchanged, the width of the top surface of the groove will decrease, and the sealing surface area in contact with the seal 3 will be reduced.

[0040] Combination Figure 4 As shown, in this embodiment, the first elastic groove 11 and the second elastic groove 21 are symmetrical structures with the same dimensions. The width W1 of the first elastic groove 11 and the top surface of the groove, and the width W2 of the second elastic groove 21 and the top surface of the groove are both 1.9 mm. The width L1 of the inclined surface of the first elastic groove 11 and the width L2 of the inclined surface of the second elastic groove 21 are both 0.45 mm. The width of the top surface of the groove and the width of the inclined surface are controlled in a suitable ratio to ensure that when the top surface of the groove is subjected to force, the pressure can be transmitted to the inclined surface. The pressure is absorbed through elastic deformation, and the force on each metal electrode plate is automatically adjusted.

[0041] In other embodiments, the dimensions of the first elastic groove 11 and the second elastic groove 21 may be the same or different. The width W1 of the top surface of the first elastic groove 11 is limited to between 1 and 2 mm, and the width L1 of the inclined surface is limited to between 0.4 and 0.6 mm. The width W2 of the top surface of the second elastic groove 21 is limited to between 1 and 2 mm, and the width L2 of the inclined surface is limited to between 0.4 and 0.6 mm. This controls the pressure absorption effect and the protrusion height of the elastic groove, ensuring that the flow channel dimensions of the first metal electrode 1 and the second metal electrode 2 are within the design range.

[0042] In this embodiment, the thickness D of the elastic layer 32 is 600 μm. The elastic layer 32 has a certain thickness, which can offset assembly tolerances and ensure contact between the adhesive layer and the elastic groove. In other embodiments, to avoid local stress concentration, the thickness D of the elastic layer 32 is limited to between 300 and 600 μm, while the thicknesses of the first adhesive layer 31 and the second adhesive layer 33 are generally less than or equal to 5 μm, which has little impact on the overall thickness of the seal 3.

[0043] Combination Figure 5 As shown, the seal 3 has an overlapping area 34 that simultaneously contacts the top surface of the first elastic groove 11 and the top surface of the second elastic groove 21. Within the overlapping area 34, the first elastic groove 11, the second elastic groove 21, and the seal 3 can work together to automatically adjust the pressure on the metal plate.

[0044] Ideally, the first elastic groove 11 and the second elastic groove 21 are symmetrically arranged, such as... Figure 4 As shown, at this time, the sealing parts 3 that contact the first elastic groove 11 and the second elastic groove 21 completely overlap. The width of the overlapping area 34 is the width of the top surface of the groove of the first elastic groove 11 or the second elastic groove 21. The larger the width of the overlapping area 34, the larger the corresponding sealing contact surface, and the better the sealing effect. However, in reality, there will be assembly tolerances. The first metal plate 1 and the second metal plate 2 of adjacent single cells will be offset, as shown in the following situation. Figure 5 As shown, the first elastic groove 11 and the second elastic groove 21 are not completely aligned. The sealing structure provided by the various embodiments of the present invention can absorb large assembly tolerances, and an ideal sealing effect can be obtained simply by ensuring that the width D of the overlapping area 34 is greater than or equal to 0.5 mm.

[0045] Ideally, the first elastic groove 11 and the second elastic groove 21 are symmetrically arranged, and their deformation after being subjected to force is also symmetrical. However, due to assembly tolerances, in reality, the deformation of the first elastic groove 11 and the second elastic groove 21 is generally different. Furthermore, in some adjacent single cells, the deformation of the first elastic groove 11 is larger, while in other adjacent single cells, the deformation of the second elastic groove 21 is larger. This makes it impossible to guarantee the consistency of the sealing structure between the single cells. To solve this problem, in some preferred embodiments, the first elastic groove 11 and the second elastic groove 21 are designed with different sizes, such as... Figure 5 As shown, the width of the top surface of the first elastic groove 11 is greater than the width of the top surface of the second elastic groove 21, and the wall thickness of the first elastic groove 11 is greater than the wall thickness of the second elastic groove 21. Thus, when the first elastic groove 11 and the second elastic groove 21 are subjected to the same force, the deformation of the second elastic groove 21 of each single cell will always be greater than that of the first elastic groove 11. This results in good consistency of the sealing structure between the assembled single cells, uniform stress on the metal plates, and uniform performance of each single cell.

[0046] The pressure required for assembling the fuel cell stack sealing structure provided in the above embodiment is significantly reduced compared to the existing pressure-type sealing structure. The cost of assembly equipment and sealing materials is reduced, and disassembly and assembly are convenient. After assembly, the deformation of the sealing component 3 is small. The single cells in the fuel cell stack can be disassembled and reassembled, and the sealing performance can still be guaranteed. It has a good prospect for industrial application and promotion.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A fuel cell stack sealing structure, characterized in that, The device includes a first metal electrode plate (1), a second metal electrode plate (2), and a sealing element (3). The first metal electrode plate (1) is the cathode / anode plate of a single cell, and the second metal electrode plate (2) is the anode / cathode plate of another adjacent single cell. The sealing element (3) is disposed between the first metal electrode plate (1) and the second metal electrode plate (2). The sealing element (3) includes a first adhesive layer (31), an elastic layer (32), and a second adhesive layer (33) stacked together. The first metal electrode plate (1) has a first elastic groove (11) protruding toward the sealing element (3), and the second metal electrode plate (2) has a first elastic groove (11) protruding toward the sealing element (3). The second elastic groove (21) protrudes towards the seal (3), the first adhesive layer (31) is bonded to the top surface of the first elastic groove (11), the second adhesive layer (33) is bonded to the top surface of the second elastic groove (21), the cross-section of the first elastic groove (11) and the second elastic groove (21) is an isosceles trapezoid with an upper base angle ranging from 120° to 160°, the width of the top surface of the first elastic groove (11) is greater than the width of the top surface of the second elastic groove (21), and the wall thickness of the first elastic groove (11) is greater than the wall thickness of the second elastic groove (21).

2. The fuel cell stack sealing structure according to claim 1, characterized in that, The first adhesive layer (31) and the second adhesive layer (33) are made of pressure-sensitive adhesive, and the elastic layer (32) is made of rubber.

3. The fuel cell stack sealing structure according to claim 2, characterized in that, The thickness of the elastic layer (32) ranges from 300 to 600 μm.

4. The fuel cell stack sealing structure according to claim 1, characterized in that, The projection of the seal (3) on the first metal electrode plate (1) covers the first elastic groove (11), and the projection of the seal (3) on the second metal electrode plate (2) covers the second elastic groove (21).

5. The fuel cell stack sealing structure according to claim 1, characterized in that, The width of the top surface of the first elastic groove (11) is between 1 and 2 mm, the width of the inclined surface of the first elastic groove (11) is between 0.4 and 0.6 mm, the width of the top surface of the second elastic groove (21) is between 1 and 2 mm, and the width of the inclined surface of the second elastic groove (21) is between 0.4 and 0.6 mm.

6. The fuel cell stack sealing structure according to claim 5, characterized in that, The seal (3) has an overlapping area (34) that simultaneously contacts the top surface of the first elastic groove (11) and the top surface of the second elastic groove (21).

7. The fuel cell stack sealing structure according to claim 6, characterized in that, The width of the overlapping area (34) is greater than or equal to 0.5 mm.

8. A battery stack, characterized in that, Includes the fuel cell stack sealing structure as described in any one of claims 1-7.

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