CN212783524U

CN212783524U - Monopolar plate, bipolar plate and fuel cell

Info

Publication number: CN212783524U
Application number: CN202021865391.0U
Authority: CN
Inventors: 王思偲; 王阳; 薛晓婷; 刘智亮; 宋平
Original assignee: Gree Electric Appliances Inc of Zhuhai
Current assignee: Gree Electric Appliances Inc of Zhuhai
Priority date: 2020-08-31
Filing date: 2020-08-31
Publication date: 2021-03-23
Anticipated expiration: 2030-08-31

Abstract

The present application provides a unipolar plate, a bipolar plate, and a fuel cell. This unipolar plate includes gas inlet and gas outlet, and gas inlet sets up the first end at the minor face of unipolar plate, and gas outlet sets up the second end at the minor face of unipolar plate, and unipolar plate still includes gas flow channel (1), and gas flow channel (1) extends along the minor face direction of unipolar plate, and the one end and the gas inlet intercommunication of gas flow channel (1), the other end and the gas outlet intercommunication of gas flow channel (1), and gas flow channel (1) are S-shaped or zigzag. According to the unipolar plate, the bipolar plate and the fuel cell, the reaction time of gas can be prolonged, and the mass transfer capacity of the gas can be enhanced.

Description

Monopolar plate, bipolar plate and fuel cell

Technical Field

The application relates to the technical field of fuel cells, in particular to a unipolar plate, a bipolar plate and a fuel cell.

Background

The fuel cell is a device for directly converting chemical energy of fuel into electric energy, has the advantages of high energy conversion rate, environmental friendliness, low operation temperature and the like, and is a clean energy technology with great development prospect. The metal bipolar plate is a core component of the proton exchange membrane fuel cell, and compared with graphite and composite bipolar plates, the metal bipolar plate has obvious advantages, such as good heat conduction and electric conductivity, good gas barrier property, high mechanical strength and the like, and is gradually becoming a technical trend and a research hotspot of designing high-power-density fuel cells.

The bipolar plate has a plurality of important functions of collecting conduction current, supporting a membrane electrode, uniformly conveying and isolating reaction gas, circulating cooling liquid, quickly dissipating heat and the like, and restricts the performance and durability of the fuel cell. The transport characteristics of the cooling medium, the reaction medium, in the bipolar plate flow field have a significant impact on the performance and durability of the fuel cell. Therefore, the bipolar plate design must compromise the mass transfer and water removal requirements of the reactant gases. However, the flowing direction of the reaction medium in the fuel cell is parallel to the plane of the plate, and the mass transfer concentration gradient caused by the electrochemical reaction is perpendicular to the plane of the plate, so how to organically combine the mass transfer enhancement of the reaction medium flowing on the flow field plane with the electrochemical reaction enhancement is a technical difficulty in the design of the fuel cell.

In addition, since the bipolar plate operates in a high-current acidic environment, the electrochemical corrosion resistance of the bipolar plate also determines the reliability of the bipolar plate and the life of the fuel cell. Therefore, advances in cooling medium flow field management design and corrosion resistance of the plates are critical to the development of metallic bipolar plate components.

The working medium circulating in the flow channel is a multiphase mixture of reaction gas, steam and condensed water. The water comes from the reduction reaction of the cathode catalyst layer, enters the cathode and anode flow channels through diffusion (through the diffusion layer) and is discharged out of the flow channels along with the gas flow. The timely discharge of the water generated by the reaction can obviously improve the performance of the fuel cell, on one hand, the flooding of the catalyst layer is avoided (so that the electrochemical corrosion of the catalyst is avoided), and on the other hand, the blockage of a diffusion mass transfer channel of the reaction gas is avoided (so that the fuel starvation on the catalyst layer is avoided). Therefore, the fluidity of the working medium inside the flow passage is extremely important.

In the bipolar plate known at present, the cathode flow field and the anode flow field are designed by adopting direct current channels, the path is short, and the contact time and the reaction area are insufficient, so that the reaction time of gas is insufficient, and the mass transfer of the gas is poor.

SUMMERY OF THE UTILITY MODEL

Therefore, an object of the present invention is to provide a unipolar plate, a bipolar plate, and a fuel cell, which can increase the reaction time of gas and enhance the mass transfer capability of gas.

In order to solve the above problem, the present application provides a unipolar plate, including gas inlet and gas outlet, gas inlet sets up the first end at the minor face of unipolar plate, and gas outlet sets up the second end at the minor face of unipolar plate, and unipolar plate still includes the gas flow way, and the gas flow way extends along the minor face direction of unipolar plate, and the one end and the gas inlet intercommunication of gas flow way, the other end and the gas outlet intercommunication of gas flow way, and the gas flow way is S-shaped or zigzag.

Preferably, the protrusions of the first side of the gas flow channel correspond to the depressions of the second side of the gas flow channel, and the depressions of the first side of the gas flow channel correspond to the protrusions of the second side of the gas flow channel.

Preferably, the gas flow channels are multiple and arranged at intervals along the length direction of the unipolar plate, and two adjacent gas flow channels are spaced by the guide structure.

Preferably, the guide structure includes a flow guide portion and a connection portion, and the flow guide portion and the connection portion are sequentially connected and alternately arranged along a width direction of the unipolar plate.

Preferably, the cross section of the flow guide part is in a shape of diamond, circle, ellipse, drop or regular polygon.

Preferably, the outer side of the outermost gas flow channel is trapezoidal.

Preferably, the gas inlet and the gas outlet are diagonally arranged at both ends of the gas flow channel.

Preferably, two adjacent gas flow channels are communicated by a gas inlet at the gas inlet end; and/or two adjacent gas flow channels are communicated at the outlet end by a gas outlet.

Preferably, the gas inlet includes a hydrogen inlet and an air inlet, the gas outlet includes a hydrogen outlet and an air outlet, the hydrogen inlet and the air inlet are located at a first end of the gas flow channel, the hydrogen outlet and the air outlet are located at a second end of the gas flow channel, the hydrogen inlet and the air inlet are alternately arranged along a length direction of the unipolar plate, and the hydrogen outlet and the air outlet are alternately arranged along the length direction of the unipolar plate.

Preferably, a bolt through hole is arranged between the hydrogen inlet and the air inlet; and/or a bolt through hole is arranged between the hydrogen outlet and the air outlet.

Preferably, a flow guiding structure is provided at the gas inlet and/or the gas outlet.

Preferably, the flow guiding structure is in a straight shape, a drop shape or a zigzag shape.

Preferably, the flow guide structures are matched to form a flow guide channel, and the flow guide channel is splayed or jellyfish-shaped.

Preferably, the flow guide structures cooperate to form a flow guide channel, and the flow guide channel is of an outwardly expanding structure at the gas inlet.

Preferably, the four corners of the unipolar plate are provided with connecting holes, the periphery of each connecting hole is provided with a jellyfish-shaped supporting structure, and the tentacles of the supporting structures face the inner side of the unipolar plate.

Preferably, the unipolar plate further comprises a cooling liquid inlet, a cooling liquid outlet and a cooling liquid channel, the cooling liquid channel is connected between the cooling liquid inlet and the cooling liquid outlet, and the gas flow field area is larger than or equal to the cooling liquid flow field area.

According to another aspect of the present application, there is provided a bipolar plate comprising a unipolar plate, the unipolar plate being the unipolar plate described above.

According to another aspect of the present application, there is provided a fuel cell comprising the above-described monopolar plate or the above-described bipolar plate.

The application provides a unipolar plate, including gas inlet and gas outlet, gas inlet sets up the first end at the minor face of unipolar plate, and gas outlet sets up the second end at the minor face of unipolar plate, and unipolar plate still includes gas flow channel, and gas flow channel extends along unipolar plate ' S minor face direction, and gas flow channel ' S one end and gas inlet intercommunication, gas flow channel ' S the other end and gas outlet intercommunication, and gas flow channel are S-shaped or zigzag. This application is through making the gas flow way form S-shaped or zigzag structure, can utilize S-shaped or zigzag structure to form the water conservancy diversion, reduce working medium reaction zone runner flow resistance, increase gas flow way drainage ability, avoid taking place the drainage dead angle, adopt S-shaped or zigzag flow way structure, it is higher to make reaction gas flow resistance compare in the direct current way, the length of the whole flow path of reaction gas has been increased, gaseous reaction time has been increased, the possibility of crossing the flow field ridge along vertical direction has been strengthened, and reaction gas crosses the vertical downward diffusion flow of flow field ridge, must pass through the contact area between polar plate and the porous diffusion layer of membrane electrode, thereby discharge and the reaction gas diffusion mass transfer of reactant in this area have been strengthened, gas mass transfer ability has been strengthened.

Drawings

Figure 1 is a block diagram of an anode plate according to an embodiment of the present application;

FIG. 2 is a structural view of a cathode plate according to an embodiment of the present application;

fig. 3 is a gas flow path diagram of a unipolar plate according to an embodiment of the present application;

figure 4 is a schematic view of a guide structure of an anode plate according to an embodiment of the present application;

fig. 5 is a first flow directing channel configuration at the gas inlet for a unipolar plate according to an embodiment of the present application;

fig. 6 is a block diagram of a second type of flow directing channel at the gas inlet for a unipolar plate according to an embodiment of the present application;

fig. 7 is a block diagram of a third flow directing channel at the gas inlet for a unipolar plate according to an embodiment of the present application.

The reference numerals are represented as:

1. a gas flow channel; 2. a flow guide part; 3. a connecting portion; 4. a hydrogen inlet; 5. a hydrogen outlet; 6. an air inlet; 7. an air outlet; 8. a coolant inlet; 9. a coolant outlet; 10. passing a hole through a bolt; 11. a flow guide structure; 12. a flow guide channel; 13. a support structure; 14. and connecting the holes.

Detailed Description

Referring to fig. 1 to 7 in combination, according to an embodiment of the present application, the unipolar plate includes a gas inlet and a gas outlet, the gas inlet is disposed at a first end of a short side of the unipolar plate, the gas outlet is disposed at a second end of the short side of the unipolar plate, the unipolar plate further includes a gas flow channel 1, the gas flow channel 1 extends along the direction of the short side of the unipolar plate, one end of the gas flow channel 1 is communicated with the gas inlet, the other end of the gas flow channel 1 is communicated with the gas outlet, and the gas flow channel 1 is S-shaped or zigzag.

This application is through making the gas flow path form S-shaped or zigzag structure, can utilize S-shaped or zigzag structure to form the water conservancy diversion, reduce the working medium reaction zone runner flow resistance of the gas flow path 1 that extends along the minor face direction of unipolar plate, increase the drainage ability of gas flow path 1, avoid taking place the drainage dead angle, adopt S-shaped or zigzag flow path structure, it is higher to make reaction gas flow resistance compare in the direct current way, the length of the whole flow path of reaction gas has been increased, gaseous reaction time has been increased, the possibility of crossing the flow field back along vertical direction has been strengthened, and reaction gas crosses the vertical downward diffusion flow of flow field back, must pass through the contact area between polar plate and the porous diffusion layer of membrane electrode, thereby discharge and the reaction gas diffusion mass transfer of reactant in this area have been strengthened, gas mass transfer ability has been strengthened.

The gas flow channels 1 are arranged at intervals along the length direction of the unipolar plate, a single gas flow channel 1 extends along the short side direction of the unipolar plate, and two adjacent gas flow channels 1 are spaced by the guide structure. The utility model provides a gas flow channel 1 is a plurality of, and a plurality of gas flow channel 1 arranges along the length direction of unipolar plate to make the quantity of gas flow channel 1 can select according to the size of fuel cell power, through the quantity that changes gas flow channel 1, reasonable adjustment fuel cell's size, make fuel cell's size and power phase-match, and can obtain great active area, and make fuel cell still can keep higher, stable, even local electrical property.

In the flowing process of the reaction gas, one part of the reaction gas directly flows linearly from the middle part of the gas flow channel 1, so that a local gas short circuit is formed, and the other part of the reaction gas flows in an S shape or a zigzag shape under the flow guide effect of the S-shaped or zigzag flow channel structure, so that the flowing path of the reaction gas is lengthened, the reaction time of the reaction gas is prolonged, meanwhile, the gas flow needing to cross the ridge of the flow field is greatly increased, the diffusion efficiency of the reaction gas is improved, and the mass transfer capacity of the gas is improved.

The protrusions of the first side of the gas flow channel 1 correspond to the depressions of the second side of the gas flow channel 1, and the depressions of the first side of the gas flow channel 1 correspond to the protrusions of the second side of the gas flow channel 1. Because the bulges and the depressions of the two side walls of the gas flow channel 1 form dislocation, the wave crest of the first side of the gas flow channel 1 is opposite to the wave trough of the second side, and the wave trough of the first side is opposite to the wave crest of the second side, so that an S-shaped or zigzag flow guide structure is more favorably formed, and the flow guide efficiency of the gas flow channel 1 to reaction gas is increased.

In order to reduce the flow resistance of the reaction gas and enhance the diffusion capacity of the reaction gas, a guide structure is arranged at each corner and the gas confluence position, the guide structure comprises a flow guide part 2 and a connecting part 3, and the flow guide part 2 and the connecting part 3 are sequentially connected and alternately arranged along the width direction of the unipolar plate. The flow guide part 2 is embodied in an island form, except that the resistance and the speed of reaction gas are smaller in the steering process, the flow field of cooling fluid is arranged on the back of the island, the flow resistance of the cooling fluid is also reduced, and the flow guide part plays a role in guiding, when flowing working medium is collected in each island and then flows downstream, the heat of the cooling fluid can be comprehensively cooled in the island, the heat at each part of the bipolar plate is uniformly distributed, the condition of uneven cold and heat is avoided, and the cooling fluid can be ensured to be transferred to each corner of the flow field. The "island" structure described above may also be applied to spiral, divergent, etc. flow field structures.

In the present embodiment, the cross section of the flow guide part 2 is in a shape of diamond, circle, ellipse, drop or regular polygon. As shown in fig. 4, the cross section of the flow guide part 2 at a is circular, the cross section of the flow guide part 2 at B is elliptical, the cross section of the flow guide part 2 at C is drop-shaped, the cross section of the flow guide part 2 at D is regular hexagon, the cross section of the flow guide part 2 at E is regular octagon, the cross section of the flow guide part 2 at F is regular decagon, and the cross section of the flow guide part 2 at G is regular pentagon. As shown in fig. 1, the cross section of the flow guide part 2 is diamond-shaped.

In this embodiment, the outer side edges of the two gas flow channels 1 located at the outermost side are continuous trapezoids, so that the path length of the reaction gas at the bending position can be increased, and meanwhile, an inclined flow guide inclined plane can be formed at the tail end position, the design performance of the flow field is improved, water flow is discharged more easily, the flow path of the reaction gas is further optimized, and the reaction gas can more easily cross the ridge of the flow field and reach the contact area between the polar plate and the membrane electrode porous diffusion layer.

The gas inlet and the gas outlet are arranged at opposite angles at two ends of the gas flow channel 1, the positions of the gas inlet and the gas outlet can be reasonably designed according to the flow path of the gas flow channel 1, so that the direction of the gas inlet is matched with the flow direction of the gas flow channel 1 at the position of the gas inlet, the direction of the gas outlet is matched with the flow direction of the gas flow channel 1 at the position of the gas outlet, the flow resistance of the reaction gas is further reduced, and the diffusion capacity of the reaction gas is enhanced.

The adjacent two gas channels 1 are communicated at the gas inlet end by a gas inlet; and/or two adjacent gas flow channels 1 are communicated at the outlet end by a gas outlet.

The gas inlet includes hydrogen import 4 and air intlet 6, the gas outlet includes hydrogen export 5 and air outlet 7, hydrogen import 4 and air intlet 6 are located the first end of gas flow channel 1, hydrogen export 5 and air outlet 7 are located the second end of gas flow channel 1, hydrogen import 4 and air intlet 6 arrange along the length direction of unipolar plate in turn, hydrogen export 5 and air outlet 7 arrange along the length direction of unipolar plate in turn, can rationally arrange gaseous exit position, make gaseous exit position and gas flow channel 1's structure phase-match, form great reaction gas flow field area, improve fuel cell's performance.

A bolt through hole 10 is arranged between the hydrogen inlet 4 and the air inlet 6; and/or a bolt through hole 10 is arranged between the hydrogen outlet 5 and the air outlet 7. Because the unipolar plate is long, if in the process of forming the bipolar plate, only the four corners are fixed by bolts, the problem of insufficient fixing capacity of the middle position is caused, the separation of the middle polar plate is easily caused, and the bipolar plate is damaged or fails. This application is guaranteeing that gaseous exit arranges under the condition that satisfies the requirement, sets up a plurality of bolt via holes 10 on unipolar plate's length direction to make bolt via hole 10 arrange with gaseous exit in turn, can guarantee the stability of connection structure between the bipolar plate, avoid the not enough problem of middle part joint strength, improve bipolar plate structural stability, can avoid again leading to the fact the interference to gaseous exit, improved bipolar plate's structural performance.

The gas inlet and/or the gas outlet are/is provided with a flow guide structure 11, and the flow guide structure 11 is in a straight line shape, a drop shape or a zigzag shape. The plurality of flow guiding structures 11 cooperate with each other to form a flow guiding channel 12, and at the gas inlet, the flow guiding channel 12 is an outward expanding structure, where the outward expanding structure means that the gas flow area of the flow guiding channel 12 is gradually increased along the gas flow direction. In the process that gas flows to the gas flow channel 1 from the gas inlet, the flow channel area is gradually increased, so that the flow resistance of fluid flow at the reaction gas inlet can be effectively reduced, the flow resistance is small, and the mass transfer and diffusion capacity is strong.

The diversion channel 12 is in a splayed shape or a jellyfish shape. The flow guide structures 11 are designed at the inlet and the outlet of the reaction gas, the flow guide structures 11 adopt shapes of drop, snake, bionic jellyfish tentacles and the like, when the reaction gas is introduced from the outside and is introduced into a flow field, the guide flow channel and the drop structure with the angle theta less than or equal to 90 degrees with the vertical direction are utilized, the flow guide structure has better conduction efficiency and smaller resistance, and the reaction gas can be better diffused into the flow field. By adopting the flow guide structure, the bionic principle can be utilized to the maximum extent in the flowing process of the working medium, the disturbance degree of the working medium in the flowing process is improved under the action of greatly reducing resistance and a certain centrifugal force, the working medium is more easily conducted downwards, and the flow guide structure has certain capacity of crossing a ridge area of a flow field and strengthens the mass transfer capacity of gas in a membrane electrode in a contact area.

The four corners of the unipolar plate are provided with connecting holes 14, the periphery of the connecting holes 14 is provided with a jellyfish-shaped supporting structure 13, and the tentacle of the supporting structure 13 faces the inner side of the unipolar plate. The connecting holes 14 are positioning pin holes and screw column through holes, the peripheries of the positioning pin holes and the screw column through holes are supported by the jellyfish-shaped supporting structures 13, the polar plates can be reinforced on one side, the jellyfish feelers are in the plate-shaped deformation direction in the pressing and stacking process, and the positioning and supporting force is enhanced through the reinforcing ribs, so that a more reliable back structure is obtained.

The unipolar plate further comprises a cooling liquid inlet 8, a cooling liquid outlet 9 and a cooling liquid flow channel, wherein the cooling liquid flow channel is connected between the cooling liquid inlet 8 and the cooling liquid outlet 9, and the area of the gas flow field is larger than or equal to that of the cooling liquid flow field.

In the embodiment, as shown in fig. 3, D2 is greater than D1, and the width of the reactant gas channel is greater than or equal to the width of the coolant fluid channel, so that the gas flow field area is effectively greater than or equal to the coolant fluid field area, and the working performance of the whole fuel cell is effectively ensured.

The flow channel structure can increase the flow area of a cooling working medium, the gathering area is designed at the island structure, the central area can be increased, the heat transfer performance is stable, the heat transfer capacity is high, the temperature distribution of the heat dissipation surface is uniform, and the dynamic response is good.

The unipolar plate flow field structure is particularly suitable for designing large-scale composite flow fields. The modularized design concept is adopted, the consistency of the structure and the performance of the flow field can be ensured, the expansion is easy, and the uniformity of the flow on the air side can be ensured. Meanwhile, the multi-position guiding and converging structure is more beneficial to prolonging the working medium flow path, reducing the resistance, increasing the disturbance degree, obtaining high-efficiency heat dissipation capacity and balancing the heating area; the cooling device can form a grid or netted cooling liquid flowing space, has smaller flow resistance and more uniform distribution, plays a cooling effect to the maximum extent and achieves the heating balance.

According to an embodiment of the present application, the bipolar plate comprises a unipolar plate, the unipolar plate being the unipolar plate described above.

According to an embodiment of the present application, a fuel cell includes the above-described unipolar plate or the above-described bipolar plate.

It is readily understood by a person skilled in the art that the advantageous ways described above can be freely combined, superimposed without conflict.

The present invention is not intended to be limited to the particular embodiments shown and described, but is to be accorded the widest scope consistent with the principles and novel features herein disclosed. The foregoing is only a preferred embodiment of the present application, and it should be noted that, for those skilled in the art, several modifications and variations can be made without departing from the technical principle of the present application, and these modifications and variations should also be considered as the protection scope of the present application.

Claims

1. The unipolar plate is characterized by comprising a gas inlet and a gas outlet, wherein the gas inlet is arranged at a first end of a short side of the unipolar plate, the gas outlet is arranged at a second end of the short side of the unipolar plate, the unipolar plate further comprises a gas flow channel (1), the gas flow channel (1) extends along the direction of the short side of the unipolar plate, one end of the gas flow channel (1) is communicated with the gas inlet, the other end of the gas flow channel (1) is communicated with the gas outlet, and the gas flow channel (1) is S-shaped or zigzag; the gas flow channels (1) are arranged at intervals along the length direction of the unipolar plate, and two adjacent gas flow channels (1) are spaced by a guide structure; the guide structure comprises a flow guide part (2) and a connecting part (3), wherein the flow guide part (2) and the connecting part (3) are sequentially connected and alternately arranged along the width direction of the unipolar plate.

2. The unipolar plate according to claim 1, characterized in that the elevations of the first side of the gas flow channel (1) correspond to the depressions of the second side of the gas flow channel (1), the depressions of the first side of the gas flow channel (1) corresponding to the elevations of the second side of the gas flow channel (1).

3. Unipolar plate according to claim 1, characterised in that the cross-section of the flow guides (2) is rhomboidal, circular, oval, drop-shaped or regular polygonal.

4. Unipolar plate according to claim 1, characterised in that the outer side edges of the outermost gas flow channels (1) are trapezoidal.

5. The unipolar plate according to claim 1, wherein the gas inlet and the gas outlet are arranged diagonally at both ends of the gas flow channel (1).

6. The unipolar plate according to claim 1, wherein two adjacent gas flow channels (1) are connected at the gas inlet end by a gas inlet; and/or two adjacent gas flow channels (1) are communicated at the outlet end by a gas outlet.

7. The unipolar plate according to claim 1, wherein the gas inlets comprise a hydrogen inlet (4) and an air inlet (6), the gas outlets comprise a hydrogen outlet (5) and an air outlet (7), the hydrogen inlet (4) and the air inlet (6) are located at a first end of the gas flow channel (1), the hydrogen outlet (5) and the air outlet (7) are located at a second end of the gas flow channel (1), the hydrogen inlet (4) and the air inlet (6) are alternately arranged along a length direction of the unipolar plate, and the hydrogen outlet (5) and the air outlet (7) are alternately arranged along the length direction of the unipolar plate.

8. The unipolar plate according to claim 7, characterized in that bolt through holes (10) are provided between the hydrogen inlet (4) and the air inlet (6); and/or a bolt through hole (10) is arranged between the hydrogen outlet (5) and the air outlet (7).

9. Unipolar plate according to one of claims 1 to 8, characterised in that a flow-guiding structure (11) is provided at the gas inlet and/or the gas outlet.

10. The unipolar plate according to claim 9, characterized in that the flow-guiding structure (11) is in the shape of a straight line, of a drop or of a sawtooth.

11. The unipolar plate according to claim 10, wherein the flow-directing structures (11) cooperate to form flow-directing channels (12), the flow-directing channels (12) being splayed.

12. The unipolar plate according to claim 10, wherein the flow-directing structures (11) cooperate to form flow-directing channels (12), the flow-directing channels (12) being flared structures at the gas inlet.

13. Unipolar plate according to one of claims 1 to 8, characterized in that the four corners of the unipolar plate are provided with connection holes (14).

14. The unipolar plate according to any one of claims 1 to 8, further comprising a coolant inlet (8), a coolant outlet (9), and a coolant flow channel connected between the coolant inlet (8) and the coolant outlet (9), the gas flow field area being greater than or equal to the coolant flow field area.

15. A bipolar plate comprising a unipolar plate, wherein said unipolar plate is according to any one of claims 1 to 14.

16. A fuel cell comprising the unipolar plate of any one of claims 1 to 14 or the bipolar plate of claim 15.