Fuel cell bipolar plate and stack

Abstract

The present invention discloses a fuel cell bipolar plate and stack, which relates to the field of fuel cell stack design, including a first plate and a second plate, the key points of which are that a first side of a first flow channel of each first plate is provided with a plurality of first protrusions, the first protrusions form a first concave block on the second side of the first flow channel, a second side of a second flow channel of each second plate is provided with a plurality of second protrusions, the second protrusions form a second concave block on the first side of the second flow channel, and the gap between the first concave block and the second concave block located in the same column of the first plate and the second plate vertically and the gap between the second concave block and the first concave form a third flow channel. Different from other nested bipolar plates, the third flow channel of the present invention is in a cross relationship with the first flow channel and the second flow channel, and the third flow channel is formed by shrinking the first flow channel and the second flow channel by a certain height, and the flow channel height can be reduced by one, thereby reducing the thickness of the bipolar plate and improving the volume power density of the fuel cell.

Description

Technical Field

[0001] The present invention relates to the field of fuel cell stack design, and in particular to a fuel cell bipolar plate and a fuel cell stack. Background Art

[0002] A fuel cell is a power generation device that converts the chemical energy in fuel and oxidant directly into electrical energy through electrochemical reactions. It has the advantages of high energy conversion rate, no pollution and low noise. A single cell of a fuel cell is composed of a plate and a membrane electrode, and multiple cells are stacked into a fuel cell stack. The volume power density of a fuel cell is calculated in the national standard using the volume of all cells between the current collecting plates as the denominator. Therefore, the thickness of a single cell is an important factor affecting the volume power density of a fuel cell. The thickness of a traditional single cell is composed of the thickness of the plate substrate × 2 + the height of the cathode flow channel + the height of the anode flow channel + the thickness of the membrane electrode after compression, which makes the volume power density of the fuel cell relatively low. In view of the above problems, it is necessary to study and design a new type of fuel cell bipolar plate and stack to overcome the problems existing in existing fuel cells. Summary of the invention

[0003] In order to solve the problem of low volume power density of fuel cells due to excessive thickness of single cells in existing fuel cells, the present invention provides a fuel cell bipolar plate and a fuel cell stack.

[0004] The technical solution adopted by the present invention to achieve the above-mentioned object is: a fuel cell bipolar plate, comprising a first electrode plate and a second electrode plate, a first side of the flow channel area of ​​the first electrode plate is transversely provided with a plurality of first ridges, a first flow channel for the flow of a first working medium is formed between two adjacent first ridges, and the first ridge forms a first groove on the second side of the flow channel area of ​​the first electrode plate;

[0005] A plurality of second ridges are transversely arranged on the second side of the second electrode plate flow channel region, a second flow channel for the flow of the second working medium is formed between two adjacent second ridges, and the second ridges form a second groove on the first side of the second electrode plate flow channel region;

[0006] A plurality of first protrusions are provided on the first side of each of the first flow channels, and the first protrusions form a first recess on the second side of the first flow channel. A plurality of second protrusions are provided on the second side of each of the second flow channels, and the second protrusions form a second recess on the first side of the second flow channel. The first electrode plate and the second electrode plate are nested with each other, and the first side of the second electrode plate is fitted with the second side of the first electrode plate. The first side of the second flow channel of the second electrode plate is assembled in the second side of the first groove of the first electrode plate. The gap between the first recess and the second groove of the first electrode plate and the second electrode plate vertically located in the same column and the gap between the second recess and the first groove form a third flow channel for the flow of a third working medium.

[0007] In a fuel cell bipolar plate according to some embodiments of the present invention, the height of the first protrusion is smaller than the depth of the first flow channel, and the height of the second protrusion is smaller than the depth of the second flow channel, thereby ensuring smooth flow of the third working medium as well as the flow of the first working medium and the second working medium.

[0008] In a fuel cell bipolar plate according to some embodiments of the present invention, the first electrode plate and the second electrode plate are both provided with a first working medium inlet, a first working medium outlet, a second working medium inlet, a second working medium outlet, a third working medium inlet and a third working medium outlet, the first working medium inlet of the first electrode plate corresponds to the first working medium inlet of the second electrode plate, the first working medium outlet of the first electrode plate corresponds to the first working medium outlet of the second electrode plate, the second working medium inlet of the first electrode plate corresponds to the second working medium inlet of the second electrode plate, the second working medium outlet of the first electrode plate corresponds to the second working medium outlet of the second electrode plate, the third working medium inlet of the first electrode plate corresponds to the third working medium inlet of the second electrode plate, and the third working medium outlet of the first electrode plate corresponds to the third working medium outlet of the second electrode plate.

[0009] In a fuel cell bipolar plate according to some embodiments of the present invention, the first flow channel and the second flow channel are both serpentine flow channels, the total lateral length of the first flow channel is an integer multiple of the lateral period of the first flow channel, and the total lateral length of the second flow channel is an integer multiple of the lateral period of the second flow channel.

[0010] According to a fuel cell bipolar plate of some embodiments of the present invention, the first polar plate is an anode plate, the first flow channel is used for the flow of anode working medium, the second polar plate is a cathode plate, the second flow channel is used for the flow of cathode working medium, and the third flow channel is used for the flow of cooling working medium.

[0011] According to a fuel cell bipolar plate of some embodiments of the present invention, the first polar plate is a cathode plate, the first flow channel is used for the flow of cathode working medium, the second polar plate is an anode plate, the second flow channel is used for the flow of anode working medium, and the third flow channel is used for the flow of cooling working medium.

[0012] The present invention also provides a fuel cell stack, comprising a plurality of the above-mentioned fuel cell bipolar plates and a plurality of membrane electrodes, a membrane electrode is provided between each of the two pairs of the bipolar plates, the two adjacent pairs of the bipolar plates are centrally symmetrically arranged, and the bipolar plates on both sides of the membrane electrode are stacked after being relatively rotated 180°, the first ridge of the bipolar plate located above and the second ridge of the bipolar plate located below are arranged oppositely, and the flow channels between the plates on both sides of the membrane electrode form a serpentine cross structure. If the centrally symmetrical feature of the two adjacent pairs of bipolar plates of the present invention is not used, two types of positive and negative plates are required, which not only increases the cost of an additional set of stamping dies, but also increases the risk of mixing during production. After using the centrally symmetrical feature of the two adjacent pairs of bipolar plates of the present invention, the flow channels between the plates form a serpentine cross, which greatly alleviates the contact resistance of the first ridge and the second ridge relative to each other and the influence of the increased diffusion distance.

[0013] According to a fuel cell stack of some embodiments of the present invention, the thickness of the region corresponding to the flow channel region of the membrane electrode and the first electrode plate or the flow channel region of the second electrode plate is less than the thickness of other regions. The support structure outside the flow channel region of the first electrode plate and the second electrode plate is higher than the height of the flow channel region, and the structure outside the flow channel region of the first electrode plate and the second electrode plate is a non-nested structure, resulting in an increase in the flow resistance of the first working medium, the second working medium and the third working medium outside the flow channel region. In order to solve this problem, the membrane electrode is designed to be thick inside the flow channel region and thin outside the flow channel region, and the support structure outside the flow channel region corresponding to the first electrode plate and the second electrode plate is designed to be higher than the height of the flow channel region, thereby utilizing the thickness difference between the inside and outside of the flow channel region of the membrane electrode to reduce the flow resistance outside the flow channel region.

[0014] A fuel cell bipolar plate of the present invention has an inspection interface on one side. The inspection interface is assembled with the rotation of the upper and lower bipolar plates. After the rotation, the inspection interface will also form the same structure at the central symmetry, which is conducive to designing a higher strength inspection plug-in.

[0015] A fuel cell bipolar plate and stack of the present invention has a bipolar plate structure that is different from other nested bipolar plates. The third flow channel of the present invention is in a cross relationship with the first flow channel and the second flow channel. The third flow channel is formed by shrinking the first flow channel and the second flow channel to a certain height, and the flow channel height can be reduced by one, thereby reducing the thickness of the bipolar plate and improving the volume power density of the fuel cell. The present invention reduces the original two sets of anode and cathode single-stage plates to one set each through the central symmetric arrangement of two adjacent pairs of bipolar plates and the design of serpentine flow channels. Through the height difference between the flow channel area and the non-flow channel area of ​​the anode and cathode single-stage plates, the height outside the flow channel area is increased in combination with a membrane electrode with a thickness difference, thereby reducing the flow resistance outside the flow channel area. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 2 is a schematic diagram of the main structure of a bipolar plate according to an embodiment of the present invention;

[0017] Figure 2 is a partial axial schematic diagram of the flow channel area of ​​a bipolar plate according to an embodiment of the present invention;

[0018] Figure 3 The present invention Figure 2 A schematic diagram of the first side of the first electrode plate;

[0019] Figure 4 The present invention Figure 2 Schematic diagram of the cross section at AA;

[0020] Figure 5 It is a schematic diagram of the coordination relationship between the bipolar plates and the membrane electrode without using the central symmetry of two adjacent pairs of bipolar plates;

[0021] Figure 6 It is a schematic diagram of the coordination relationship between the bipolar plates and the membrane electrode using two adjacent pairs of bipolar plates that are centrally symmetrical;

[0022] Figure 7 Schematic diagram of the cross-section of the bipolar plate and membrane electrode.

[0023] In the figure: 1. first electrode plate, 1-1. first ridge, 1-2. first flow channel, 1-3. first groove, 1-4. first protrusion, 2. second electrode plate, 2-1. second ridge, 2-2. second flow channel, 2-3. first groove, 2-4. second protrusion, 2-5. third flow channel, 3. first working medium inlet, 4. first working medium outlet, 5. second working medium inlet, 6. second working medium outlet, 7. third working medium inlet, 8. third working medium outlet, 9. membrane electrode, 10. inspection interface. DETAILED DESCRIPTION

[0024] The following embodiments of the present invention are described in further detail in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0025] In the description of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. The terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. In addition, in the description of the present invention, unless otherwise specified, the meaning of "multiple" is two or more.

[0026] A fuel cell bipolar plate of this embodiment, such as Figure 1-Figure 4 As shown, it includes a first electrode plate 1 and a second electrode plate 2, a first side of the flow channel area of ​​the first electrode plate 1 is provided with a plurality of first ridges 1-1 transversely, a first flow channel 1-2 for the flow of a first working medium is formed between two adjacent first ridges 1-1, and the first ridge 1-1 forms a first groove 1-3 on the second side of the flow channel area of ​​the first electrode plate 1; a second side of the flow channel area of ​​the second electrode plate 2 is provided with a plurality of second ridges 2-1 transversely, a second flow channel 2-2 for the flow of a second working medium is formed between two adjacent second ridges 2-1, and the second ridge 2-1 forms a second groove 2-3 on the first side of the flow channel area of ​​the second electrode plate 2; a plurality of first protrusions 1-4 are provided on the first side of each first flow channel 1-2, and the first protrusions The protrusions 1-4 form a first concave block on the second side of the first flow channel 1-2, and each second flow channel 2-2 is provided with a plurality of second protrusions 2-4 on the second side, and the second protrusions 2-4 form a second concave block on the first side of the second flow channel 2-2. The first electrode plate 1 and the second electrode plate 2 are nested with each other, and the first side of the second electrode plate 2 is fitted with the second side of the first electrode plate 1. The first side of the second flow channel 2-2 of the second electrode plate 2 is assembled in the second side of the first groove 1-3 of the first electrode plate 1. The gap between the first concave block and the second groove 2-3 located in the same column vertically of the first electrode plate 1 and the second electrode plate 2 and the gap between the second concave block and the first groove 1-3 form a third flow channel 2-5 for the flow of a third working medium. In this embodiment, the first electrode plate 1 and the second electrode plate 2 are nested for use, which can reduce the thickness of the single bipolar plate.

[0027] The height of the first protrusion 1-4 is smaller than the depth of the first flow channel 1-2 to prevent blocking the flow of the first working medium in the first flow channel 1-2. The height of the second protrusion 2-4 is smaller than the depth of the second flow channel 2-2 to prevent blocking the flow of the second working medium in the second flow channel 2-2. This can ensure the smooth flow of the third working medium as well as the flow of the first working medium and the second working medium.

[0028] The first electrode plate 1 and the second electrode plate 2 are both provided with a first working medium inlet 3, a first working medium outlet 4, a second working medium inlet 5, a second working medium outlet 6, a third working medium inlet 7 and a third working medium outlet 8. The first working medium inlet 3 of the first electrode plate corresponds to the first working medium inlet 3 of the second electrode plate. The first working medium inlet 3 is used to flow the first working medium into the bipolar plate. The first working medium outlet 4 of the first electrode plate corresponds to the first working medium outlet 4 of the second electrode plate. The first working medium outlet 4 is used to flow out of the first working medium in the bipolar plate. The second working medium inlet 5 of the first electrode plate corresponds to the first working medium outlet 4 of the second electrode plate. The second working medium inlet 5 corresponds to the second working medium inlet 5, and the second working medium outlet 6 of the first electrode plate corresponds to the second working medium outlet 6 of the second electrode plate, and the second working medium outlet 6 is used for the outflow of the second working medium in the bipolar plate. The third working medium inlet 7 of the first electrode plate corresponds to the third working medium inlet 7 of the second electrode plate, and the third working medium inlet 7 is used for the inflow of the third working medium into the bipolar plate. The third working medium outlet 8 of the first electrode plate corresponds to the third working medium outlet 8 of the second electrode plate, and the third working medium outlet 8 is used for the outflow of the third working medium in the bipolar plate.

[0029] The first flow channel 1-2 and the second flow channel 2-2 are both serpentine flow channels. The total transverse length of the first flow channel 1-2 is an integer multiple of the transverse period of the first flow channel 1-2, and the total transverse length of the second flow channel 2-2 is an integer multiple of the transverse period of the second flow channel 2-2.

[0030] As a preference of this embodiment, the first electrode plate 1 is an anode plate, the first flow channel 1-2 is used for the flow of anode working medium, the second electrode plate 2 is a cathode plate, the second flow channel 2-2 is used for the flow of cathode working medium, and the third flow channel 2-5 is used for the flow of cooling working medium.

[0031] As another preference of this embodiment, the first electrode plate 1 is a cathode plate, the first flow channel 1-2 is used for the flow of cathode working medium, the second electrode plate 2 is an anode plate, the second flow channel 2-2 is used for the flow of anode working medium, and the third flow channel 2-5 is used for the flow of cooling working medium.

[0032] Different from other nested bipolar plates, the cooling channel of this embodiment is in a cross relationship with the cathode and anode channels, and the cooling channel is formed by the cathode and anode channels being retracted to a certain height.

[0033] This embodiment also provides a fuel cell stack, including a plurality of the above-mentioned fuel cell bipolar plates and a plurality of membrane electrodes 9, a membrane electrode 9 is provided between two pairs of bipolar plates, the two adjacent pairs of bipolar plates are centrally symmetrically arranged, and the bipolar plates on both sides of the membrane electrode 9 are stacked after being rotated 180° relative to each other, the first ridge 1-1 of the upper bipolar plate is arranged opposite to the second ridge 2-1 of the lower bipolar plate, and the flow channels between the plates on both sides of the membrane electrode 9 form a serpentine cross structure. Figure 5 As shown, the central symmetry feature of the two adjacent pairs of bipolar plates of the present invention is not used. It can be seen that the ridge of the anode plate is directly below the cathode flow channel, which is very unfavorable for fuel cells. On the one hand, the flow channel to the ridge will cause the local pressure to decrease, thereby increasing the contact resistance. On the other hand, it will increase the diffusion distance of the cathode / anode working medium, resulting in a decrease in the concentration of reactants in the reaction zone. Both factors will lead to a decrease in the power generation performance of the fuel cell. In addition, two types of anode and cathode plates are required, which not only increases the cost of an additional set of stamping dies, but also increases the risk of mixing during production.

[0034] like Figure 6 As shown, after using the central symmetry feature of two adjacent pairs of bipolar plates of the present invention, the bipolar plates on both sides of the membrane electrode 9 are stacked after being rotated 180° relative to each other, and the flow channels between the plates on both sides of the membrane electrode 9 form a serpentine cross, which also greatly alleviates the contact resistance of the first ridge and the second ridge set relative to each other and the influence of the increased diffusion distance.

[0035] like Figure 7 As shown, the thickness of the area corresponding to the flow channel area of ​​the first electrode plate 1 or the flow channel area of ​​the second electrode plate 2 is greater than the thickness of other areas. The structure outside the flow channel area of ​​the first electrode plate and the second electrode plate is a non-nested structure, which increases the flow resistance of the first working medium, the second working medium and the third working medium outside the flow channel area. In order to solve this problem, the membrane electrode is designed to be thick inside the flow channel area and thin outside the flow channel area. The corresponding support structure outside the flow channel area on the first electrode plate and the second electrode plate is higher than the height of the flow channel area, thereby utilizing the thickness difference between the inside and outside of the flow channel area of ​​the membrane electrode to reduce the flow resistance outside the flow channel area.

[0036] A fuel cell bipolar plate of the present embodiment is also provided with an inspection interface 10 on one side. The inspection interface 10 is used to install an inspection plug-in, which is used to detect the plate voltage. When the stack data is abnormal, the inspection plug-in can quickly check the voltage of the single plate and troubleshoot the fault. The inspection interface 10 is assembled with the upper and lower groups of bipolar plates, and the inspection interface 10 will form the same structure at the central symmetric position after rotation, which is also conducive to designing a higher strength inspection plug-in.

[0037] The embodiments of the present invention are given for the purpose of illustration and description, and are not intended to be exhaustive or to limit the invention to the disclosed forms. Many modifications and variations will be apparent to those of ordinary skill in the art. The embodiments are selected and described in order to better illustrate the principles and practical applications of the present invention and to enable those of ordinary skill in the art to understand the present invention and thereby design various embodiments with various modifications suitable for specific uses.

Claims

1. A fuel cell stack, characterized in that: A fuel cell stack comprises a plurality of fuel cell bipolar plates and a plurality of membrane electrodes (9), wherein a membrane electrode (9) is provided between two pairs of the bipolar plates, the bipolar plates comprising a first electrode plate (1) and a second electrode plate (2), a plurality of first ridges (1-1) are transversely provided on a first side of a flow channel region of the first electrode plate (1), a first flow channel (1-2) for a first working medium to flow is formed between two adjacent first ridges (1-1), and the first ridges (1-1) form a first groove (1-3) on a second side of the flow channel region of the first electrode plate (1); A plurality of second ridges (2-1) are transversely arranged on the second side of the flow channel region of the second electrode plate (2); a second flow channel (2-2) for the flow of a second working medium is formed between two adjacent second ridges (2-1); and the second ridges (2-1) form a second groove (2-3) on the first side of the flow channel region of the second electrode plate (2); A plurality of first protrusions (1-4) are provided on the first side of each first flow channel (1-2), and the first protrusions (1-4) form a first concave block on the second side of the first flow channel (1-2); a plurality of second protrusions (2-4) are provided on the second side of each second flow channel (2-2), and the second protrusions (2-4) form a second concave block on the first side of the second flow channel (2-2); the first electrode plate (1) and the second electrode plate (2) are nested with each other, the first side of the second electrode plate (2) is in contact with the second side of the first electrode plate (1), the first side of the second flow channel (2-2) of the second electrode plate (2) is assembled in the second side of the first groove (1-3) of the first electrode plate (1), and the gap between the first groove and the second groove (2-3) located in the same column of the first electrode plate (1) and the second electrode plate (2) vertically and the gap between the second groove and the first groove (1-3) form a third flow channel (2-5) for the flow of a third working medium; The two adjacent pairs of bipolar plates are centrally symmetrically arranged, and the bipolar plates on both sides of the membrane electrode (9) are stacked after being rotated 180 degrees relative to each other, the first ridge (1-1) of the bipolar plate located above and the second ridge (2-1) of the bipolar plate located below are arranged opposite to each other, and the flow channels between the plates on both sides of the membrane electrode (9) form a serpentine cross structure; The thickness of the membrane electrode (9) in the region corresponding to the flow channel region of the first electrode plate (1) or the flow channel region of the second electrode plate (2) is greater than the thickness of other regions; A patrol inspection interface (10) is also provided on one side of the fuel cell bipolar plate.

2. A fuel cell stack according to claim 1, characterized in that: The height of the first protrusion (1-4) is smaller than the depth of the first flow channel (1-2), and the height of the second protrusion (2-4) is smaller than the depth of the second flow channel (2-2).

3. A fuel cell stack according to claim 2, characterized in that: The first electrode plate (1) and the second electrode plate (2) are both provided with a first working medium inlet (3), a first working medium outlet (4), a second working medium inlet (5), a second working medium outlet (6), a third working medium inlet (7) and a third working medium outlet (8).

4. A fuel cell stack according to claim 3, characterized in that: The first flow channel (1-2) and the second flow channel (2-2) are both serpentine flow channels, the total transverse length of the first flow channel (1-2) is an integer multiple of the transverse period of the first flow channel (1-2), and the total transverse length of the second flow channel (2-2) is an integer multiple of the transverse period of the second flow channel (2-2).

5. A fuel cell stack according to any one of claims 1 to 4, characterized in that: The first electrode plate (1) is an anode plate, the first flow channel (1-2) is used for the flow of an anode working medium, the second electrode plate (2) is a cathode plate, the second flow channel (2-2) is used for the flow of a cathode working medium, and the third flow channel (2-5) is used for the flow of a cooling working medium.

6. A fuel cell stack according to any one of claims 1 to 4, characterized in that: The first electrode plate (1) is a cathode plate, the first flow channel (1-2) is used for the flow of cathode working medium, the second electrode plate (2) is an anode plate, the second flow channel (2-2) is used for the flow of anode working medium, and the third flow channel (2-5) is used for the flow of cooling working medium.

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