A balanced force structure for a flat end plate fuel cell stack

Abstract

The present invention provides a planar end plate type fuel cell stack balanced force structure, the fuel cell stack includes a blind end plate, a blind end current collecting plate, a blind end edge node plate, an intermediate node plate, a gas outlet end edge node plate, a gas outlet end current collecting plate, and a gas outlet end plate, which are arranged in sequence, and also includes a balancing plate, wherein one balancing plate is respectively arranged between the blind end plate and the blind end current collecting plate and between the gas outlet end plate and the gas outlet end current collecting plate; the balancing plate is provided with a plurality of flow channels on the side surface facing the blind end plate or the gas outlet end plate, the flow channels are arranged along the length direction of the balancing plate, and the depth of the flow channels is normally distributed in the width direction of the balancing plate. The technical solution of the present invention solves the problems of uneven force on the edge nodes and differences with the intermediate nodes in the prior art, improves the reliability of the stack, and saves costs.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and in particular to a force-bearing structure of an edge node of a planar end plate type fuel cell stack. Background Art

[0002] Fuel cells can efficiently and cleanly convert the chemical energy of the reactants into electrical energy, and have the characteristics of low noise and easy start and stop, making them an ideal energy conversion medium in line with future low-carbon development. Fuel cells are usually composed of multiple bipolar plates and membrane electrodes stacked on top of each other, and reinforced by end plates at both ends to form a stack. In addition, due to actual usage requirements, the end plates at both ends of the stack should not be too thick or too heavy, which will significantly reduce the specific power of the stack. The use of non-planar stacks in production can easily limit the external system integration of the stack. Therefore, efficient and simple planar end plate fuel cells have become the commonly used type of stack. During the actual production and assembly process, the end plates of the flat end plate type fuel cell stack are connected and fixed by bolts on all sides. The force on the four sides of the end plate is greater, and the force in the middle position is smaller, causing the end plate to arch toward the middle and bend and deform, making the force on the edge nodes close to the end plate side very uneven. If the power of the fuel cell stack itself increases and the plane size of the bipolar plate increases, the uneven force on the edge nodes of the fuel cell stack and the difference between the edge nodes and the middle nodes will be further aggravated, affecting the fluid distribution of the edge nodes of the fuel cell stack, the mechanical matching status of the sub-components, the life of the membrane electrode, and the low-temperature startup performance, and aggravating the edge node effect of the fuel cell stack. Summary of the Invention

[0003] To address the aforementioned technical issues of uneven stress on edge sections and differences in stress across stack sections, a planar end plate fuel cell stack balance structure is provided. This invention primarily utilizes a balance plate with a three-dimensional curved surface structure similar to a flow channel to improve the stress on the stack edge sections during assembly and pre-tightening, ensuring uniform stress on the stack edge sections. This reduces the stress differences between stack sections and improves stack consistency.

[0004] The technical means adopted in the present invention are as follows:

[0005] A planar end plate type fuel cell stack balanced force structure, the fuel cell stack includes a blind end plate, a blind end current collecting plate, a blind end edge node plate, an intermediate node plate, a gas outlet end edge node plate, a gas outlet end current collecting plate and a gas outlet end plate arranged in sequence, and also includes a balancing plate, one balancing plate is respectively arranged between the blind end plate and the blind end current collecting plate and between the gas outlet end plate and the gas outlet end current collecting plate; the balancing plate is provided with a plurality of flow channels on one side surface facing the blind end plate or the gas outlet end plate, the flow channels are arranged along the length direction of the balancing plate, and the flow channel depth is normally distributed in the width direction of the balancing plate.

[0006] Furthermore, the equalizing plate includes a base, the flow channels are provided on one side surface of the base, the other side surface of the base is a plane, flow channel ridges are formed between adjacent flow channels, and the flow channel ridges are an arc-shaped structure in the length direction.

[0007] Furthermore, the flow channel depth D1 on the equalizing plate is 0.5~2D, the width W1 is 0.8~1.2W, and the width of the flow channel ridge is L1=0.8~1.2L, wherein D, W and L respectively represent the depth, width and width of the flow channel ridge in the active area of ​​the single polar plate in the intermediate section plate.

[0008] Furthermore, a three-cavity structure is provided at both ends of the gas outlet end collecting plate, and the length of the balancing plate is smaller than the distance between the three-cavity structures at both ends of the gas outlet end collecting plate.

[0009] Furthermore, the intermediate electrode plate includes a cathode side monopolar plate and an anode side monopolar plate, the cathode side monopolar plate and the anode side monopolar plate are made of graphite or metal, and the balancing plate is made of the same material as the cathode side monopolar plate and the anode side monopolar plate.

[0010] Furthermore, the cathode side monopolar plate and the anode side monopolar plate are made of graphite, and the cathode side monopolar plate and the anode side monopolar plate are bonded together to form the intermediate section plate. The compressive strength of the intermediate section plate is not less than 20 MPa, the electrical conductivity in the thickness direction is not less than 25 S / cm, and the thermal conductivity is not less than 15 W / m·k.

[0011] Furthermore, the cathode side monopolar plate, the anode side monopolar plate and the balancing plate are made of stainless steel, and the cathode side monopolar plate and the anode side monopolar plate are welded to form the intermediate section plate.

[0012] Compared with the prior art, the present invention has the following advantages:

[0013] 1. The present invention provides a balanced force structure for a planar end-plate fuel cell stack. By adding balancing plates on both sides of the stack, during the assembly pre-tightening process, the upper end of the balancing plate fits against the inner side of the end plate to compensate for the bending deformation of the end plate, while the lower end of the balancing plate base still maintains a planar structure, so that the edge nodes are evenly stressed. This effectively solves problems such as poor flow distribution at the edge nodes, excessive local shear force on the proton exchange membrane, and under-pressure or over-pressure of the carbon paper. It improves the consistency of each node of the stack and maintains a good specific power of the stack. During the operation of the stack, the flow channel structure on the balancing plate can dissipate heat, reduce the operating temperature of the stack, and ensure operational stability.

[0014] 2. The present invention provides a planar end plate type fuel cell stack balanced force structure. Without changing the original stack structure design, only a balancing plate is added to the two ends of the stack, and a flow channel structure is set on the balancing plate to reduce the weight of the balancing plate itself, so that the volume and weight of the stack are not significantly increased. It is not only suitable for graphite plate stacks, but also for metal plate stacks. It has simple process and high reliability, and can be repeatedly assembled and maintained, saving production costs.

[0015] In summary, the application of the balancing plate in the technical solution of the present invention can improve the stress conditions on the edge nodes of the battery stack without changing the stack structure, thereby improving the consistency of the battery stack. Therefore, the technical solution of the present invention solves the problem of differential stress on the edge nodes and the middle nodes in the prior art, and the uneven stress on the edge nodes.

[0016] Based on the above reasons, the present invention can be widely promoted in the fields of fuel cell technology and the like. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0018] Figure 1 This is a structural schematic diagram of the equalizing plate of the present invention.

[0019] Figure 2 This is a schematic diagram of the structure of the planar end plate fuel cell stack described in the present invention.

[0020] Figure 3 The figure is a schematic diagram of the assembly process of the balancing plate of the present invention with the blind-end plate and the blind-end current collecting plate at the blind-end side of the stack.

[0021] Figure 4 The figure is a schematic diagram of the assembly process of the balancing plate of the present invention at the gas inlet end side of the fuel cell stack, the gas inlet end plate and the gas inlet end current collecting plate.

[0022] Figure 5 This is a finite element analysis cloud diagram of the force between the balancing plate and the blind end plate of the present invention.

[0023] In the figure: 11, blind end plate; 12, gas port end plate; 121, hydrogen cavity port; 122, oxygen cavity port; 123, water cavity port; 21, blind end current collecting plate; 22, gas port end current collecting plate; 3, intermediate node plate; 41, blind end edge node plate; 42, gas port end edge node plate; 5, balancing plate. DETAILED DESCRIPTION

[0024] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0025] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0026] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0027] Unless otherwise specifically stated, the relative arrangement of the parts and steps, numerical expressions and numerical values ​​described in these embodiments do not limit the scope of the present invention. At the same time, it should be clear that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship. The techniques, methods and equipment known to ordinary technicians in the relevant fields may not be discussed in detail, but where appropriate, the techniques, methods and equipment should be considered as part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following figures, so once an item is defined in one figure, it does not need to be further discussed in subsequent figures.

[0028] In the description of the present invention, it should be understood that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "horizontal, vertical, vertical, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention: the directional words "inside and outside" refer to the inside and outside relative to the outline of each component itself.

[0029] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used herein to describe the spatial positional relationship of a device or feature to other devices or features as shown in the figures. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figures. For example, if the device in the drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below their position devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0030] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0031] Example 1

[0032] like Figure 1-2As shown, the present invention provides a planar end plate type fuel cell stack balanced force structure, comprising a blind end plate 11, a blind end current collecting plate 21, a blind end edge node plate 41, an intermediate node plate 3, a gas outlet end edge node plate 42, a gas outlet end current collecting plate 22 and a gas outlet end plate 12, wherein a balancing plate 5 is respectively arranged between the blind end plate 11 and the blind end current collecting plate 21 and between the gas outlet end plate 12 and the gas outlet end current collecting plate 22, and the balancing plate 5 is provided with a plurality of flow channels on one side surface facing the blind end plate 11 or the gas outlet end plate 12, the flow channels are arranged along the length direction of the balancing plate 5, and the flow channel depth is normally distributed in the width direction of the balancing plate 5, the balancing plate 5 includes a base, the flow channels are arranged on one side surface of the base, the other side surface of the base is a plane, there is a flow channel ridge between adjacent flow channels, and the flow channel ridge in the length direction is a curved surface structure, and the specific shape can be obtained through finite element simulation as needed; as shown Figures 3-4 As shown, during the assembly pre-tightening process, the arc-shaped flow channel ridge of the balancing plate 5 can compensate for the bending deformation of the blind end plate 11 and the gas port end plate 12, and play a role in supporting the end plates. The flow channel structure can reduce the weight of the balancing plate 5 to meet the power-to-weight ratio of the fuel cell stack. The flow channel structure can also increase the heat dissipation area of ​​the balancing plate 5 and reduce the temperature.

[0033] Furthermore, the flow channel on the equalizing plate 5 has a depth D1 of 0.5 to 2D, a width W1 of 0.8 to 1.2W, and a width L1 of the flow channel ridge of 0.8 to 1.2L, wherein D, W, and L represent the depth and width of the flow channel in the active area of ​​the single polar plate in the intermediate section plate and the width of the flow channel ridge, respectively.

[0034] Furthermore, a three-cavity structure including a hydrogen cavity 121, an oxygen cavity 122, and a water cavity 123 is provided at both ends of the gas inlet end current collecting plate 22, and a sealing groove is provided around the three-cavity structure. The length of the balancing plate 5 is less than the distance between the three-cavity structures at both ends of the gas inlet end current collecting plate 22.

[0035] Furthermore, the intermediate electrode plate 3 includes a cathode side monopolar plate and an anode side monopolar plate, and the cathode side monopolar plate and the anode side monopolar plate are an integrated structure of base and flow channel. Flow channels are opened within the active area of ​​the cathode side monopolar plate and the anode side monopolar plate, and the depth D, flow channel width W and flow channel ridge width L of each flow channel are the same.

[0036] Furthermore, in this embodiment, the cathode side monopolar plate and the anode side monopolar plate are made of graphite, and the blind end edge node plate 41, the gas port end edge node plate 42 and the equalizing plate 5 are all made of the same material as the cathode side monopolar plate and the anode side monopolar plate;

[0037] Furthermore, the cathode side monopolar plate and the anode side monopolar plate are bonded together to form the intermediate section plate 3, and the intermediate section plate 3 has a compressive strength of not less than 20 MPa, an electrical conductivity in the thickness direction of not less than 25 S / cm, and a thermal conductivity of not less than 15 W / m·k;

[0038] Finite element analysis is performed on the stress conditions of the balancing plate 5 and the blind end plate 11. Figure 5 It can be seen that the deformation of the middle area of ​​the blind end plate 11 is large, and the deformation of the side of the balancing plate 5 close to the blind end current collecting plate 21 is relatively uniform. Since the force-bearing structure of the balancing plate 5 compensates for the bending deformation of the end plate 11, the deformation of the inner side of the balancing plate 5 is more uniform, and the force transmitted to the blind end current collecting plate 21 and the blind end edge node plate 41 will also be evenly distributed, so that the force within the active area of ​​the edge node is uniform.

[0039] Example 2

[0040] The only difference between this embodiment and embodiment 1 is that the cathode side monopolar plate, the anode side monopolar plate and the equalizing plate 5 are made of stainless steel, the blind end edge node plate 41 and the gas port end edge node plate 42 are made of the same material as the cathode side monopolar plate and the anode side monopolar plate, and the cathode side monopolar plate and the anode side monopolar plate are welded to form the intermediate node plate 3.

[0041] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements 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 planar end plate type fuel cell stack balanced force structure, the fuel cell stack comprising a blind end plate, a blind end current collecting plate, a blind end edge node plate, an intermediate node plate, a gas port end edge node plate, a gas port end current collecting plate and a gas port end plate arranged in sequence; characterized in that: It also includes a balancing plate, one of which is respectively provided between the blind end plate and the blind end current collecting plate, and between the gas outlet end plate and the gas outlet end current collecting plate; a plurality of flow channels are provided on a surface of the balancing plate facing the blind end plate or the gas outlet end plate, the flow channels are provided along the length direction of the balancing plate, and the depth of the flow channels is normally distributed in the width direction of the balancing plate; The equalizing plate includes a base, the flow channels are arranged on one side surface of the base, the other side surface of the base is a plane, a flow channel ridge is formed between adjacent flow channels, and the flow channel ridge surface is a curved surface structure in the length direction.

2. The balanced force structure of a planar end plate type fuel cell stack according to claim 1, characterized in that: The flow channel depth D1 on the balancing plate is 0.5~2D, the width W1 is 0.8~1.2W, and the width L1 of the flow channel ridge is 0.8~1.2L, wherein D, W and L represent the depth, width and width of the flow channel ridge in the active area of ​​the single polar plate in the intermediate section plate, respectively.

3. The balanced force structure of a planar end plate type fuel cell stack according to claim 1, characterized in that: A three-cavity structure is respectively provided at both ends of the gas outlet end collecting plate, and the length of the balancing plate is smaller than the distance between the three-cavity structures at both ends of the gas outlet end collecting plate.

4. The balanced force structure of a planar end plate type fuel cell stack according to claim 1, characterized in that: The intermediate section plate includes a cathode side monopolar plate and an anode side monopolar plate, the cathode side monopolar plate and the anode side monopolar plate are made of graphite or metal, and the balancing plate is made of the same material as the cathode side monopolar plate and the anode side monopolar plate.

5. The balanced force structure of a planar end plate type fuel cell stack according to claim 4, characterized in that: The cathode side monopolar plate and the anode side monopolar plate are made of graphite. The cathode side monopolar plate and the anode side monopolar plate are bonded together to form the intermediate section plate. The compressive strength of the intermediate section plate is not less than 20 MPa, the electrical conductivity in the thickness direction is not less than 25 S / cm, and the thermal conductivity is not less than 15 W / m•k.

6. The balanced force structure of a planar end plate type fuel cell stack according to claim 4, characterized in that: The cathode side monopolar plate, the anode side monopolar plate and the balancing plate are made of stainless steel, and the cathode side monopolar plate and the anode side monopolar plate are welded to form the intermediate section plate.

Images