CN217740579U - Bipolar plate and fuel cell - Google Patents

Abstract

The utility model provides a bipolar plate and fuel cell. The bipolar plate includes a pair of unipolar plates, each unipolar plate having opposing inner and outer surfaces, the inner surface having a reaction gas flow field formed thereon, the reaction gas flow field including a plurality of grooves arranged side-by-side, the outer surface having a plurality of ribs formed thereon corresponding to the plurality of grooves and a plurality of coolant channels defined between the plurality of ribs, wherein each rib extends along an undulating path, each rib of one of the pair of unipolar plates abuts a corresponding rib of the other unipolar plate, and a peak and a valley of each rib are offset relative to a peak and valley, respectively, of the corresponding rib to form a plurality of communication ports communicating respective coolant channels of the pair of unipolar plates, the plurality of coolant channels and the plurality of communication ports forming a coolant flow field between the pair of unipolar plates.

Description

Bipolar plate and fuel cell

Technical Field

The present invention relates to the field of fuel cell manufacturing, and more particularly, to a bipolar plate for a fuel cell and a fuel cell using the bipolar plate.

Background

Due to the advantages of energy conservation and ecological environment protection, fuel cells have become a promising power generation technology and are widely used in vehicles such as electric vehicles. However, the fuel cell generates a large amount of heat when power is supplied, and the loss of the heat in time affects the operation of the fuel cell. Therefore, efficient cooling of the fuel cell is critical to achieving high temperature operation and longer life. Fuel cells tend to dissipate heat by coolant flowing through their coolant channels. However, the coolant passage is of a passive design, and needs to be determined after the fuel gas flow passage and the oxidant gas passage are designed. In the existing design, the low pressure drop and good distribution of the fuel gas channels and the oxidant gas channels and the low pressure drop and good distribution of the coolant channels are difficult to be considered, so that the existing fuel cells usually have the problem that the performance of the fuel cells is affected due to the fact that the temperature of the downstream of the central area is increased due to insufficient coolant.

Therefore, there is a need in the art for a fuel cell that can achieve both low pressure drop and good distribution of the fuel gas channels and the oxidant gas channels and low pressure drop and good distribution of the coolant channels.

SUMMERY OF THE UTILITY MODEL

In order to solve the above-mentioned problems of the prior art, the present invention provides a bipolar plate for a fuel cell, including a pair of unipolar plates, wherein each unipolar plate has opposite inner and outer surfaces, a reaction gas flow field is formed on the inner surface, the reaction gas flow field includes a plurality of grooves arranged side by side, a plurality of ribs corresponding to the plurality of grooves and a plurality of coolant channels defined between the plurality of ribs are formed on the outer surface, wherein each rib extends along a wavy path, each rib of one of the pair of unipolar plates abuts against a corresponding rib of the other unipolar plate, and a peak and a trough of each rib are respectively offset with respect to a peak and a trough of the corresponding rib so as to form a plurality of communication ports communicating respective coolant channels of the pair of unipolar plates with each other, the plurality of coolant channels (i.e., the respective coolant channels of the pair of unipolar plates) and the plurality of communication ports forming a coolant flow field between the pair of unipolar plates.

According to an alternative embodiment of the invention, each rib has the same period and amplitude as the corresponding rib.

According to an alternative embodiment of the invention, the wave crest and the wave trough of each rib are aligned with the wave trough and the wave crest of the corresponding rib, respectively.

According to an alternative embodiment of the present invention, wherein each rib of each unipolar plate has the same amplitude and period.

According to an optional embodiment of the present invention, wherein the reactant gas flow field circulates along a first direction, and the coolant flow field circulates along a second direction, the second direction being transverse to the first direction.

In accordance with an alternative embodiment of the invention, each rib extends along a sinusoidal path.

Also in order to solve the above problems in the prior art, the present invention also provides a fuel cell including a housing containing a coolant and a stack disposed in the housing, wherein the stack includes a plurality of membrane electrode assemblies and a plurality of bipolar plates as described above, the membrane electrode assemblies and the bipolar plates being stacked together in an alternating manner.

According to an alternative embodiment of the present invention, the reactant gas flow field of each unipolar plate of each bipolar plate is sealed in the stack, and the coolant flow field of each bipolar plate communicates with the outside of the stack.

According to an alternative embodiment of the invention, the galvanic pile is immersed in the coolant.

According to an alternative embodiment of the invention, the housing is provided with a coolant inlet and a coolant outlet, respectively, at two diagonally separated corners.

The invention may be embodied in the exemplary embodiments shown in the drawings. It is to be noted, however, that the drawings are designed solely for purposes of illustration and that any variations which come within the teachings of the invention are intended to be included therein.

Drawings

The accompanying drawings illustrate exemplary embodiments of the invention. These drawings should not be construed as necessarily limiting the scope of the invention, in which:

fig. 1 is a schematic perspective view of a fuel cell according to the present invention;

figure 2 is a schematic exploded view of a fuel cell stack according to the present invention;

figure 3 is a schematic side view of a bipolar plate according to the invention and a schematic cross-sectional view thereof taken along the line III-III;

figure 4 is a schematic side view of an anode plate of a bipolar plate according to the present invention; and

fig. 5 is a schematic side view of a cathode plate of a bipolar plate according to the present invention.

Detailed Description

Further features and advantages of the present invention will become apparent from the following description, which proceeds with reference to the accompanying drawings. Exemplary embodiments of the invention are illustrated in the accompanying drawings, and the various drawings are not necessarily drawn to scale. This invention may, however, be embodied in many different forms and should not be construed as necessarily limited to the exemplary embodiments set forth herein. Rather, these exemplary embodiments are provided only to illustrate the present invention and to convey the spirit and substance of the invention to those skilled in the art.

The present invention is directed to an improved bipolar plate (BPP) for a fuel cell such as a Proton Exchange Membrane (PEM) fuel cell and a fuel cell including the same. In particular, the cathode gas flow field, the anode gas flow field (which may be collectively referred to as gas flow field or reactant gas flow field), and the coolant flow field of the bipolar plate have novel designs, thus allowing the heat dissipation performance of the fuel cell to be improved, and thus allowing the fuel cell to operate at higher loads and have an extended service life.

Alternative but non-limiting embodiments of bipolar plates and fuel cells according to the invention are described in detail below with reference to the various figures.

Referring to fig. 1, there is shown a schematic perspective view of a fuel cell according to the present invention. As shown in fig. 1, a fuel cell 100 includes a casing 110 and a stack 120 disposed in the casing 110, wherein the casing 110 contains a coolant, and the stack 120 is disposed in the casing 110 in such a manner as to be immersed in the coolant. Specifically, the housing 110 is provided with a coolant inlet 111 and a coolant outlet 112 at two corners divided along a diagonal line, respectively. In this configuration, a coolant pump, a radiator, and the like may be provided outside the fuel cell 100 to form a heat radiation line connecting the fuel cell 100, the coolant pump, the radiator, and the like in series, and after the coolant pump and the radiator are activated, the coolant may be circulated between the fuel cell 100 and the radiator to absorb heat generated by the stack 120 during operation using the coolant to help the stack 120 radiate heat. Of course, a heater may be provided on the heat dissipation line in parallel with the radiator so that the coolant is heated by the coolant pump and the heater and the stack 120 is preheated by the coolant during the winter start, which facilitates the cold start of the stack 120.

Referring to fig. 2, there is shown a schematic exploded view of a stack of fuel cells according to the present invention. As shown in fig. 2, the cell stack 120 includes a plurality of cells 121 stacked together, wherein each cell 121 includes a Membrane Electrode Assembly (MEA) 121M and an anode plate 121A and a cathode plate 121C on both sides of the MEA 121M, the anode plate 121A can deliver anode gas (e.g., hydrogen) from an anode gas source to the MEA 121M, and the cathode plate 121C can deliver cathode gas (e.g., oxygen) from a cathode gas source to the MEA 121M, and the MEA 121M provides a region (hereinafter referred to as an active region) where the anode gas and the cathode gas electrochemically react. In particular, the anode plate 121A and the cathode plate 121C of each cell 121 form a bipolar plate 121P with the cathode plate 121C and the anode plate 121A of the adjacent cell 121, wherein the anode plate 121A and the cathode plate 121C may be collectively referred to as a unipolar plate. Accordingly, the stack 120 may also be considered to be formed of a plurality of bipolar plates 121P and a plurality of mea 121M stacked together in an alternating manner. For example, in the manufacturing process, the anode plate and the cathode plate positioned at the outermost side are first arranged, then the bipolar plate 121P and the membrane electrode assembly 121M are arranged between the anode plate and the cathode plate in an alternating manner, and finally the stack 120 is formed by stacking these components together, so that the bipolar plate 121P may serve as a connecting member of the adjacent unit cells 121 to thereby function as a connecting member of the adjacent unit cells 121 to form the complete stack 120, and the bipolar plate 121P may also collect and transmit electric current generated by electrochemical reaction of anode gas and cathode gas.

Referring to fig. 3-5, there are shown schematic side views of a bipolar plate according to the present invention and the anode and cathode plates making up the bipolar plate, respectively. As shown in fig. 3 and the III-III sectional view thereof, the bipolar plate 121P may be roughly divided into a common channel region 10, a distribution region 20 and a flow field region 30, wherein the common channel region 10 is communicated with an intake channel and an exhaust channel to receive gas from a gas source without undergoing an electrochemical reaction and to discharge gas having undergone the electrochemical reaction, the distribution region 20 is used to communicate the common channel region 10 with the flow field region 30, and the flow field region 30 corresponds to an active region of the membrane electrode assembly 121M to supply cathode gas and anode gas for electrochemical reaction thereof to the active region of the membrane electrode assembly 121M. In particular, as shown in FIG. 3, one common conduit region 10 and one distribution region 20 are provided on each side of the flow field region 30.

As shown in fig. 4, the anode plate 121A has an anode gas inlet 11 and an anode gas outlet 12 formed in the common tube region 10, the anode gas inlet 11 and the anode gas outlet 12 being positioned on both sides of the flow field region 30 and extending through the anode plate 121A. The anode plate 121A also has an anode gas flow field formed in the flow field region 30, wherein the anode gas flow field communicates with the anode gas inlet 11 and the anode gas outlet 12 through the distribution pipe 21 formed in the distribution region 20. In this configuration, anode gas from the anode gas inlet 11 will be delivered to the anode gas flow field through the distribution pipe 21 located upstream of the anode gas flow field, the anode gas will participate in the electrochemical reaction in the active area of the membrane electrode assembly 121M as it flows in the anode gas flow field, and then the anode gas having undergone the electrochemical reaction will be delivered from the anode gas flow field to the anode gas outlet 12 through the distribution pipe 21 located downstream of the anode gas flow field. In particular, anode plate 121A has an anode plate inner surface 121A 'intended to face a corresponding membrane electrode assembly 121M and an anode plate outer surface 121A "opposite anode plate inner surface 121A', in the orientation shown in fig. 4, anode plate inner surface 121A 'faces the reader and anode plate outer surface 121A" faces away from the reader, wherein both distribution tubes 21 and anode gas flow fields are formed on anode plate inner surface 121A'. As shown in cross-section III-III of fig. 3 and in phantom in fig. 4, the anode gas flow field is formed by a plurality of anode plate slots 31 recessed from an anode plate inner surface 121A ', wherein each anode plate slot 31 extends along a first direction X from a respective upstream distribution tube 21 to a respective downstream distribution tube 21 to communicate with the anode gas inlet 11 and the anode gas outlet 12 through the respective distribution tube 21, and the plurality of anode plate slots 31 are spaced apart from each other along a second direction Y transverse (e.g., perpendicular) to the first direction X, and a plurality of anode plate ribs 31' are formed on the anode plate outer surface 121A "to protrude from the anode plate outer surface 121A" corresponding to the plurality of anode plate slots 31. In the manufacturing process, the anode plate groove 31 and the anode plate rib 31 'described above may be formed by punching the anode plate inner surface 121A' of the anode plate 121A. Like the plurality of anode plate grooves 31, the plurality of anode plate ribs 31 'are also spaced apart from one another along the second direction Y on the anode plate outer surface 121A ″ to thereby define anode plate coolant channels 32 between adjacent anode plate ribs 31'. In particular, each anode plate groove 31 and each anode plate rib 31' extend in a wavy (e.g., sinusoidal) path in the first direction X from a distribution region 20 upstream thereof to a distribution region 20 downstream thereof.

Cathode plate 121C has a similar configuration to anode plate 121A. As shown in fig. 5, the cathode plate 121C has a cathode gas inlet 13 and a cathode gas outlet 14 formed in the common piping region 10, the cathode gas inlet 13 and the cathode gas outlet 14 being positioned on both sides of the flow field region 30 and extending through the cathode plate 121C. The cathode plate 121C also has a cathode gas flow field formed in the flow field area 30, wherein the cathode gas flow field communicates with the cathode gas inlet 13 and the cathode gas outlet 14 through the distribution pipe 21 formed in the distribution area 20. In this configuration, cathode gas from the cathode gas inlet 13 will be delivered to the cathode gas flow field through the distribution pipe 21 located upstream of the cathode gas flow field, the cathode gas will participate in the electrochemical reaction in the active area of the membrane electrode assembly 121M as it flows in the cathode gas flow field, and then the cathode gas having undergone the electrochemical reaction will be delivered from the cathode gas flow field to the cathode gas outlet 14 through the distribution pipe 21 located downstream of the cathode gas flow field. In particular, the cathode plate 121C has a cathode plate inner surface 121C ' intended to face the respective membrane electrode assembly 121M and a cathode plate outer surface 121C "opposite the cathode plate inner surface 121C", the cathode plate inner surface 121C ' facing the reader and the cathode plate outer surface 121C "facing away from the reader in the orientation shown in fig. 5, wherein both the distribution tube 21 and the cathode gas flow field are formed on the cathode plate inner surface 121C '. As shown in the cross-section III-III of fig. 3 and the shaded portion of fig. 5, the cathode gas flow field is composed of a plurality of cathode plate grooves 33 recessed from the cathode plate inner surface 121C ', wherein each cathode plate groove 33 extends along the first direction X from the respective upstream distribution tube 21 to the respective downstream distribution tube 21 so as to communicate with the cathode gas inlet 13 and the cathode gas outlet 14 through the respective distribution tube 21, and the plurality of cathode plate grooves 33 are spaced apart from each other along the second direction Y transverse to the first direction X, while a plurality of cathode plate ribs 33' protruding from the cathode plate outer surface 121C "corresponding to the plurality of cathode plate grooves 33 are formed on the cathode plate outer surface 121C". The cathode plate grooves 33 and the cathode plate ribs 33 'may be formed by punching the cathode plate inner surface 121C' of the cathode plate 121C during the manufacturing process. Like the plurality of cathode plate grooves 33, on the cathode plate outer surface 121C ", a plurality of cathode plate ribs 33 'are also spaced apart from each other in the second direction Y, thereby defining cathode plate coolant channels 34 between adjacent cathode plate ribs 33'. In particular, each cathode plate groove 33 and each cathode plate rib 33' also extend in the first direction X along an undulating (e.g., sinusoidal) path from the distribution area 20 upstream thereof to the distribution area 20 downstream thereof.

As shown in fig. 3 and the III-III sectional view therein, bipolar plate 121P is made up of an anode plate 121A and a cathode plate 121C joined together, with an anode plate inner surface 121A 'of anode plate 121A and a cathode plate inner surface 121C' of cathode plate 121C facing away from each other, and an anode plate outer surface 121A "of anode plate 121A and a cathode plate outer surface 121C" of cathode plate 121C facing toward each other, in the orientation shown in fig. 3, with the anode plate inner surface 121A 'of anode plate 121A facing the reader and the cathode plate inner surface 121C' of cathode plate 121C facing away from the reader. In addition, each of the plurality of anode plate ribs 31 'on the anode plate outer surface 121A ″ abuts against each of the plurality of cathode plate ribs 33' on the cathode plate outer surface 121C ″, that is, each of the anode plate ribs 31 'abuts against one corresponding cathode plate rib 33', and in this configuration, the plurality of anode plate ribs 31 'and the plurality of cathode plate ribs 33' space the anode plate outer surface 121A ″ and the cathode plate outer surface 121C ″ from each other. Specifically, the crests (or troughs) of each anode plate rib 31 'and the crests (or troughs) of the corresponding cathode plate rib 33' are offset from each other along the first direction X. In this configuration, a plurality of communication ports 35 are formed which are distributed in a matrix form, specifically, each anode plate rib 31 'and the corresponding cathode plate rib 33' form a row of communication ports 35 which are arranged in the first direction X, and the plurality of anode plate ribs 31 'and the plurality of cathode plate ribs 33' form a plurality of rows of communication ports 35 which are arranged in the second direction Y, wherein each communication port 35 communicates the anode plate coolant passage 32 and the cathode plate coolant passage 34 adjacent thereto with each other, and in this configuration, each anode plate coolant passage 32 communicates with one cathode plate coolant passage 34 through one row of communication ports 35, and the anode plate coolant passage 32 and the cathode plate coolant passage 34 at both ends in the second direction Y also communicate with the outside through one row of communication ports 35. Since the common channel region 10 of the bipolar plate 121P is often sealed off from the outside, a coolant flow field extending in the second direction Y is formed in the flow field region 30 of the bipolar plate 121P, more specifically between the anode plate outer surface 121A "of the anode plate 121A and the cathode plate outer surface 121C" of the cathode plate 121C, which coolant flow field can not only remain free in the second direction Y but also have a large flow cross section due to the presence of the multiple rows of communication openings 35. In this configuration, the anode gas and the cathode gas will flow through the anode gas flow field and the cathode gas flow field generally in a first direction X, and the coolant will flow through the coolant flow field generally in a second direction Y (shown by dashed lines in the III-III cross-sectional view) transverse to the first direction X, so that both the anode gas channels, the cathode gas channels, and the coolant channels can exhibit low pressure drop and good distribution, which enables the anode gas and the cathode gas to flow smoothly through the flow field area so as to ensure efficient electrochemical reactions, and the coolant can flow smoothly through the flow field area so as to ensure efficient heat dissipation, thereby ensuring efficient operation of the fuel cell and having an extended service life.

Specifically, each anode plate rib 31 'has the same amplitude and period, and each cathode plate rib 33' has the same amplitude and period. In this configuration, each of the communication ports 35 on the columns located along the second direction Y is the same, which helps ensure uniformity in the flow of the coolant in the coolant flow field and thus improves uniformity in the heat exchange of the coolant with the anode plate and the cathode plate in the coolant flow field, thereby reliably avoiding the generation of local hot spots.

In particular, each anode plate rib 31 'has the same amplitude and period as the corresponding cathode plate rib 33'. In this configuration, each communication opening 35 formed by the same anode plate rib 31 'and the corresponding cathode plate rib 33', i.e., each communication opening 35 in the course located along the first direction X, is the same, which also helps to ensure the uniformity of the flow of the coolant in the coolant flow field, and thus improves the uniformity of the heat exchange of the coolant with the anode and cathode plates in the coolant flow field, thereby reliably avoiding the generation of local hot spots.

Of course, if the above two features are combined so that all the anode plate ribs 31 'and the cathode plate ribs 33' have the same amplitude and period, all the communication ports 35 formed are the same, which further improves the consistency of heat exchange of the coolant with the anode and cathode plates in the coolant flow field, thereby more reliably avoiding the generation of local hot spots.

Specifically, the crests and troughs of each anode plate rib 31 'are aligned with the troughs and crests, respectively, of the corresponding cathode plate rib 33' along the second direction Y. With this configuration, a larger communication port 35 can be formed to enable the coolant to flow more smoothly through the coolant flow field, which further improves the heat radiation performance.

In particular, each anode plate rib 31 'and each cathode plate rib 33' extend along a sinusoidal path. With this configuration, the anode gas and the cathode gas can flow more smoothly in the anode plate grooves 31 and the cathode plate grooves 33 corresponding to the anode plate ribs 31 'and the cathode plate ribs 33', so as to ensure smooth progress of the electrochemical reaction. Of course, it will be understood by those skilled in the art that the anode plate ribs 31 'and the cathode plate ribs 33' may also extend along paths of other wave shapes, such as zigzag shapes, and this obviously falls within the scope of the present invention.

Returning to fig. 1 and 2, in the stack 120 assembled using the bipolar plates 121P having the above-described configuration, the anode gas flow field on the anode plate 121A and the cathode gas flow field on the cathode plate 121C of each bipolar plate 121P are sealed in the corresponding unit cell 121, and the coolant flow field between the anode plate 121A and the cathode plate 121C is open to the outside. In this configuration, the stack 120 may be immersed in the coolant in the casing 110, and after the coolant pump is activated, the coolant will flow through the coolant flow field in each bipolar plate 121P, thereby efficiently dissipating heat for the respective cells 121.

Alternative but non-limiting embodiments of a bipolar plate and a fuel cell according to the invention are described in detail above with the aid of the figures. Modifications and additions to the techniques and structures, as well as re-combinations of features in various embodiments, which do not depart from the spirit and substance of the disclosure, will be readily apparent to those of ordinary skill in the art as the same becomes better understood by reference to the following detailed description. Accordingly, such modifications and additions that can be envisaged under the teaching of the present invention are to be considered as part of the present invention. The scope of the present invention includes both equivalents known at the time of filing and equivalents not yet foreseen.

Claims (10)

1. A bipolar plate for a fuel cell including a pair of unipolar plates, wherein each unipolar plate has opposite inner and outer surfaces, the inner surface having a reaction gas flow field formed thereon, the reaction gas flow field including a plurality of grooves arranged side by side, the outer surface having a plurality of ribs formed thereon corresponding to the plurality of grooves and a plurality of coolant channels defined between the plurality of ribs, wherein,

each rib extends along an undulating path, each rib of one of the pair of unipolar plates abuts a corresponding rib of the other unipolar plate, and a peak and a trough of each rib are offset relative to a peak and a trough, respectively, of the corresponding rib to form a plurality of communication ports communicating respective coolant channels of the pair of unipolar plates, the plurality of coolant channels and the plurality of communication ports forming a coolant flow field between the pair of unipolar plates.

2. The bipolar plate of claim 1 wherein each rib has the same period and amplitude as the corresponding rib.

3. A bipolar plate as claimed in claim 2, wherein the peaks and troughs of each rib are aligned with the troughs and crests, respectively, of the corresponding rib.

4. A bipolar plate as in any one of claims 1 to 3, wherein each rib of each unipolar plate has the same amplitude and period.

5. A bipolar plate as in any one of claims 1 to 3, wherein said reactant gas flow fields circulate in a first direction and said coolant flow fields circulate in a second direction, said second direction being transverse to said first direction.

6. A bipolar plate as claimed in any one of claims 1 to 3, wherein each rib extends along a sinusoidal path.

7. Fuel cell comprising a housing containing a coolant and an electric stack arranged in the housing, characterized in that the stack comprises a plurality of membrane electrode assemblies and a plurality of bipolar plates according to any one of claims 1 to 6, the membrane electrode assemblies and the bipolar plates being stacked together in an alternating manner.

8. The fuel cell of claim 7, wherein the reactant gas flow field of each monopolar plate of each bipolar plate is sealed in the stack and the coolant flow field of each bipolar plate is in communication with the exterior of the stack.

9. The fuel cell of claim 8, wherein the stack is immersed in the coolant.

10. The fuel cell according to any one of claims 7 to 9, wherein the housing is provided with a coolant inlet and a coolant outlet, respectively, at two corners divided along a diagonal line.

Images