DESC:RELATED APPLICATION

Benefit is claimed to Indian Provisional Application No. 201721020722 titled "A METAL BIPOLAR PLATE DESIGN" by KPIT Technologies Limited, filed on 14th June 2017, which is herein incorporated in its entirety by reference for all purposes.

FIELD OF THE INVENTION

The present invention generally relates to a fuel cell stack, and more particularly relates to a bi-polar metal plate for the fuel cell stack that is effective and simple in design.

BACKGROUND OF THE INVENTION

Nowadays, fuel cells are being used as a power source for many applications. Proton exchange membrane (PEM) (e.g. Hydrogen Fuel Cell) is a one of such fuel cells. PEM fuel cell stacks are commonly configured having a plurality of fuel cell elements in a stacked configuration. The fuel cell elements commonly include a pair of PEM elements separated by a conventional bi-polar plate. The conventional bi-polar plates include a pair of plates joined by adhesive seal, by brazing, and by welding. These are the key components of PEM fuel cell stacks with multifunctional character. Various materials could be used for the production of these conventional bi-polar plates. Such conventional bi-polar plates include non-porous graphite, coated metallic sheets, polymer composites, etc.

According to the prior art, the conventional bi-polar plate is formed by assembling or welding a pair of metal sheets such that a functional flow field is created on each side of the bi-polar plate assembly. These methods are expensive and are complex to adopt. The fabrication methods of the conventional bi-polar plates are the main challenges in fuel cell. Selection of the plate material, geometry of flow field design and the fabrication method are the main issues. The major challenges that are faced while using the conventional metal bi-polar plates are perpendicular channels which obstruct flow of both H2 and O2, no proper landing space for gasket and direct impact of incoming air on Kapton films which causes damage. Further, the conventional metal bi-polar plates include flow fields that may terminate the flow fields at inlet causing reduction in effective current generation area. The conventional metal bi-polar plates also lack management of pressure causing fluttering of the Kapton films.

Therefore, there is a need for a unique bi-polar metal plate that has an anode and cathode on either side of the plate, which is effective and simple in design.

SUMMARY OF THE INVENTION

The present invention herein provides a bi-polar metal plate for a fuel cell stack and a method for constructing a fuel cell, comprises an anode and a cathode on either side of a bi-polar metal plate. In one aspect, the bi-polar metal plate includes a first side being adapted to have a first set of predefined channels and a second side being adapted to have a second set of predefined channels. The first set of predefined channels on the first side of bi-polar metal plate is adapted to provide a first flow field for a first reactant, and the second set of predefined channels on the second side of the bi-polar metal plate is adapted to provide a second flow field for a second reactant. One or more first channels of the first set of predefined channels terminating at a first inlet/outlet on the first side of bi-polar metal plate are adapted to have a first bypass flow field to maintain the one or more first channels active and one or more second channels of the second set of predefined channels terminating at a second inlet/outlet on the second side of the bi-polar metal plate are adapted to have a second bypass flow field to maintain the one or more second channels active.

According to one embodiment, the first reactant is one of an anode and a cathode and the second reactant is one of the anode and the cathode.

According to an embodiment, the bi-polar metal plate includes an underpass flow field formed by at least one of one or more teeth protrusions on the first side of the bi-polar metal plates to enable flowing of coolant. In another embodiment, the underpass flow filed is formed by providing variation in height of ridges of a first flow field on the first side of the bi-polar metal plate.
In yet another embodiment, the underpass flow field is formed by providing variation in height of ridges of a second flow field on the second side of the bi-polar metal plate.

In one aspect, a fuel cell stack is described herein. The fuel cell stack includes a plurality of bi-polar metal plates, a plurality of supporting plates, a plurality of membrane electrode assembly (MEA) and a plurality of gaskets. The plurality of bi-polar metal plates is placed parallel to each other. Each plate of the plurality of bi-polar metal plates includes a first set of predefined channels on a first side and a second set of predefined channels on a second side. Each supporting plate is positioned between two bi-polar metal plates of the plurality of bi-polar metal plates. Each supporting plate includes a first bend along a flow direction and a second bend perpendicular to the flow direction to avoid cross flow of a second reactant from the second side to the first side. Each MEA is positioned between the two bi-polar metal plates of the plurality of bi-polar metal plates. The gasket is positioned on at least one side (i.e. the first side and/or the second side) of each plate of the plurality of bi-polar metal plates. Each gasket includes a plurality of protrusions on one side and a plurality of indentations on another side at regular intervals.

According to one embodiment, the first set of predefined channels on the first side of each plate is adapted to provide a first flow field for a first reactant and the second set of predefined channels on the second side of each plate is adapted to provide a second flow field for the second reactant.

According to another embodiment, one or more first channels of the first set of predefined channels terminating at a first inlet/outlet on the first side of each plate is adapted to have a first bypass flow field to maintain the one or more first channels active and one or more second channels of the second set of predefined channels terminating at a second inlet/outlet on the second side of each plate is adapted to have a second bypass flow field to maintain the one or more second channels active.

According to yet another embodiment, the fuel cell stack includes an underpass flow field to balance pressure on a pair of bi-polar metal plates of the plurality of bi-polar plates and provide cooling effect to the pair of bi-polar metal plates.

According to yet another embodiment, the underpass flow field is achieved by at least one of one or more teeth protrusions on the first side of each plate of the bi-polar metal plates to enable flowing of coolant in between the pair of bi-polar metal plates and variation in height of ridges of a second flow field and a first flow field between the pair of bi-polar metal plates.

According to yet another embodiment, each gasket of the plurality of gasket is integrated with one or more stiffeners to give stiffness and eliminate cross flow of a first reactant and the second reactant.

According to yet another embodiment, the first reactant is one of an anode and a cathode and the second reactant is one of the anode and the cathode.

In another aspect, a method for constructing a fuel cell comprising an anode and a cathode on either side of a bi-polar metal plate is described herein. The method includes creating an impression on a first side of a pair of bi-polar metal plates to form a first set of predefined channels on the first side and a second set of predefined channels on a second side of the pair of bi-polar metal plates, positioning a supporting plate on the second side of a first bi-polar metal plate of the pair of bi-polar metal plates, wherein the supporting plate comprises a first bend along a flow direction and a second bend perpendicular to the flow direction for avoiding cross flow of a second reactant from the second side to the first side, positioning a membrane electrode assembly (MEA) between the pair of bi-polar metal plates and positioning a gasket on the first side and the second side of each bi-polar metal plate of the pair of bi-polar metal plates, wherein the gasket comprises a plurality of protrusions on one side and a plurality of indentations on another side at regular intervals for attaching with each plate of the pair of bi-polar metal plates.

According to one embodiment, the method includes creating a first bypass flow field on the first side for maintaining one or more first channels of the first set of predefined channels active and creating a second bypass flow field on the second side for maintaining one or more second channels of the second set of predefined channels active.

According to another embodiment, the method includes creating an underpass flow field for balancing pressure in each plate of the pair of bi-polar metal plates by at least one of one or more teeth protrusions on the first side of each plate of the bi-polar metal plates to enable flowing of coolant in between the pair of bi-polar metal plates, and variation in height of ridges of a second flow field and a first flow field between the pair of bi-polar metal plates.

The foregoing has outlined, in general, the various aspects of the invention and is to serve as an aid to better understand the more complete detailed description which is to follow. In reference to such, there is to be a clear understanding that the present invention is not limited to the method or application of use described and illustrated herein. It is intended that any other advantages and objects of the present invention that become apparent or obvious from the detailed description or illustrations contained herein are within the scope of the present invention.

Other features of the embodiments will be apparent from the accompanying drawings and from the detailed description that follows.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The other objects, features and advantages will occur to those skilled in the art from the following description of the preferred embodiment and the accompanying drawings in which:

Figure 1 depicts a bi-polar metal plate having a first flow field and a second flow field on either side of the bi-polar metal plate, according to an embodiment of the present invention.

Figure 2 depicts a bi-polar metal plate having a first bypass flow field near a first inlet/outlet for effective increase in current generation area, according to an embodiment of the present invention.

Figure 3 depicts a pair of bi-polar metal plates having an underpass flow field to balance pressure and provide cooling effect to the pair of bi-polar metal plates of a fuel cell stack, according to an embodiment of the present invention.

Figure 4A & 4B depicts a bi-polar metal plate having a supporting plate for supporting a membrane electrode assembly (MEA) and distributing uniform pressure along a gasket, according to an embodiment of the present invention.

Figure 5 depicts a bi-polar metal plate having a gasket for avoiding buckling of the bi-polar metal plate, according to an embodiment of the present invention.

Figure 6 depicts a bi-polar metal plate having a gasket that provides underpass for a first reactant and a second reactant, according to an embodiment of the present invention.

Figure 7 is a schematic diagram of arrangement of a pair of bi-polar metal plates in a fuel cell stack, according to an embodiment of the present invention.

Figure 8 is a schematic diagram of a bi-polar metal plate illustrating flipping axis and flipping direction while assembling a pair of bi-polar metal plates in a fuel cell stack, according to an embodiment of the present invention.

The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a bi-polar metal plate of a fuel cell which comprises an anode and a cathode on either side. In the following detailed description of the embodiments of the invention, reference is made to the accompanying drawings that form a part hereof, and in which are shown by way of illustration specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that changes may be made without departing from the scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined only by the appended claims.

The specification may refer to “an”, “one” or “some” embodiment(s) in several locations. This does not necessarily imply that each such reference is to the same embodiment(s), or that the feature only applies to a single embodiment. Single features of different embodiments may also be combined to provide other embodiments.

As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless expressly stated otherwise. It will be further understood that the terms “includes”, “comprises”, “including” and/or “comprising” when used in this specification, specify the presence of stated features, integers, steps, operations, elements and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term “and/or” includes any and all combinations and arrangements of one or more of the associated listed items.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

The embodiments herein and the various features and advantages details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein can be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.

Figure 1 depicts a bi-polar metal plate 102 having a first flow field 104 and a second flow field 106 on either side of the bi-polar metal plate 102, according to an embodiment of the present invention. According to Figure 1, the bi-polar metal plate 102 includes a first set of predefined channels on a first side and a second set of predefined channels on a second side. The first set of predefined channels is adapted to provide the first flow field 104 for a first reactant. The second set of predefined channels is adapted to provide the second flow field 106 for a second reactant. In one embodiment, the first reactant is an anode and the second reactant is a cathode. In another embodiment, the first reactant is the cathode and the second reactant is the anode. The first set of predefined channels on the first side is formed by an impression on the first side during stamping. The impression on the first side of the bi-polar metal plate 102 creates corresponding ribs on the second side. The created ribs form the second set of predefined channels on the second side. In an embodiment, a reactant (e.g. the first reactant or the second reactant) on a side of the cathode is O_2. In another embodiment, the reactant (e.g. the first reactant or the second reactant) on a side of the anode is H_2. As the bi-polar metal plate 102 includes the anode and the cathode on either side, requirement of welding is completely eliminated and turnaround time is minimized during production of the bi-polar metal plate 102 in order to minimize manufacturing cost and manufacturing complexity.

Figure 2 depicts a bi-polar metal plate 102 having a first bypass flow field 204 near a first inlet/outlet 202 to increase effective current generation area, according to an embodiment of the present invention. According to Figure 2, the bi-polar metal plate 102 includes one or more first channels and one or more second channels within a first set of predefined channels and a second set of predefined channels respectively. The one or more first channels on a first side terminate near the first inlet/outlet 202 (e.g. H2 inlet/outlet) which leads to decrease in current generation area. The bi-polar metal plate 102 includes the first bypass flow field 204 to maintain the one or more terminated first channels active and increase the effective current generation area. The first bypass flow field 204 connects the one or more terminated first channels to one of channels of the first set of predefined channels to enable circulation of a first reactant on the first side. Similarly, a second bypass flow field connects one or more terminated second channels to one of channels of second set of predefined channels to enable circulation of a second reactant on a second side.

Figure 3 depicts a pair of bi-polar metal plates having an underpass flow field 304 to balance pressure and provide cooling effect to the pair of bi-polar metal plates of a fuel cell stack, according to an embodiment of the present invention. According an embodiment of the present invention, the pair of bi-polar metal plates achieves the underpass flow field 304 by providing one or more teeth protrusions on a first side of each plate of the pair of bi-polar metal plates to enable flowing of coolant in between the pair of bi-polar metal plates. According to another embodiment of the present invention, the pair of bi-polar metal plates achieves the underpass flow field by providing variation in height of ridges 302 of a second flow field and a first flow field between the pair of bi-polar metal plates. The underpass flow field 304 is adapted to balance the pressure and provide the cooling effect to the pair of bi-polar metal plates of the fuel cell stack. In an embodiment, a supporting plate, a membrane electrode assembly (MEA) and a gasket are positioned in between the pair of bi-polar metal plates.

Figure 4A & 4B depicts a bi-polar metal plate 102 having a supporting plate 402 for supporting a membrane electrode assembly (MEA) 404 and distributing uniform pressure along a gasket, according to an embodiment of the present invention. In a fuel cell stack, each supporting plate 402 is positioned between two bi-polar metal plates of a plurality of bi-polar metal plates for supporting the MEA 402 during compression of the fuel cell stack. The supporting plate 402 includes bent edges, a first bend along a flow direction and a second bend perpendicular to the flow direction for avoiding cross flow 406 of either a second reactant from a second side to a first side or a first reactant from the first side to the second side. In an embodiment, the supporting plate 402 is made of electrically insulating material. The supporting plate 402 is adapted to reduce leakage of a coolant and further provide landing space for a gasket. The supporting plate 402 further distributes uniform pressure 408 along the gasket by utilizing the first bend and the second bend and avoids fluttering of the supporting plate 402 in the fuel cell stack.

Figure 5 depicts a bi-polar metal plate 102 having a gasket 502 for avoiding buckling of the bi-polar metal plate 102, according to an embodiment of the present invention. In a fuel cell stack, the gasket 502 is positioned on a first side and a second side of each bi-polar metal plate of a pair of bi-polar metal plates. The gasket 502 includes one or more protrusions 504 on one side and one or more indentations 506 on other side at regular intervals for attaching with each plate of the pair of bi-polar metal plates. In an embodiment, each plate of the pair of bi-polar metal plates includes one or more protrusions on one side and one or more indentations 506 on other side for attaching with the gasket 502 of a plurality of gaskets in the fuel cell stack. In an embodiment, each gasket of the plurality of gaskets is positioned on the first side and the second side of each plate of the pair of bi-polar metal plates. The gasket 502 is adapted to secure the pair of bi-polar metal plates and avoid buckling during compression of the fuel cell stack. In an embodiment, the one or more protrusions 504 on the gasket 502 is adapted to provide free flow of one of a first reactant and a second reactant. In an embodiment, the gasket 502 is integrated with one or more stiffeners to provide stiffness and eliminate cross flow of a first reactant and a second reactant.

Figure 6 depicts a bi-polar metal plate 102 having a gasket 502 that provides underpass for a first reactant and a second reactant, according to an embodiment of the present invention. According to Figure 6, the gasket 502 that is attached with the bi-polar metal plate 102 provides underpass (as depicted in 602 and 604) for either the first reactant (e.g. H_2) or the second reactant (e.g. O_2) near sides, edges, a first inlet/outlet and a second inlet/outlet through one or more protrusions 504 on the gasket 502.

Figure 7 is a schematic diagram of arrangement of a pair of bi-polar metal plates in a fuel cell stack, according to an embodiment of the present invention. According to Figure 7, a schematic view of a bi-polar metal plate 102 is depicted in 702. The fuel cell stack includes a plurality of bi-polar metal plates. The plurality of bi-polar metal plates includes one or more pairs of bi-polar metal plates that are placed parallel to each other. Each pair of bi-polar metal plates includes a first bi-polar metal plate 704 and a second bi-polar metal plate 712. Each pair of bi-polar metal plates further includes a supporting plate 706, an MEA 708 and a gasket 710. The supporting plate 706 is positioned between the first bi-polar metal plate 704 and the second bi-polar metal plate 712 of each pair of bi-polar metal plates. The supporting plate 706 includes a first bend along a flow direction and a second bend perpendicular to the flow direction to avoid cross flow of a second reactant from a second side to a first side. The MEA 708 is positioned between the first bi-polar metal plate 704 and the second bi-polar metal plate 712. In an embodiment, the supporting plate, the MEA and the gasket are positioned between each pair of the plurality of bi-polar metal plates as described above to construct the fuel cell stack. In another embodiment, the gasket is integrated with one or more stiffeners to provide stiffness and eliminate cross flow of a first reactant and the second reactant. In an embodiment, the fuel cells stack includes an arrangement of combination of serpentine anode and parallel cathode.

Figure 8 is a schematic diagram of a bi-polar metal plate 102 illustrating flipping axis and flipping direction while assembling a pair of bi-polar metal plates in a fuel cell stack, according to an embodiment of the present invention. According to this embodiment, the bi-polar metal plate 102 depicts a first inlet/outlet port 802A, a second inlet/outlet port 802B, a flipping direction 804 and a flipping axis 806. In an embodiment, the bi-polar metal plate is adapted to have positioning and placement of the first inlet/outlet port 802A and the second inlet/outlet port 802B at one or more places within the bi-polar metal plate 102. The flipping axis 806 of the bi-polar metal plate 102 is adapted to vertically flip (i.e. in the flipping direction 804) the bi-polar metal plate 102 while assembling to ensure rib to rib contact with the other bi-polar metal plate in the fuel cell stack. The flipping direction 804 is depicted in Figure.8

While the specification has been described in detail with respect to specific embodiments of the invention, it will be appreciated that those skilled in the art, upon attaining an understanding of the foregoing, may readily conceive of alterations to, variations of, and equivalents to these embodiments. These and other modifications and variations to the present invention may be practiced by those of ordinary skill in the art, without departing from the scope of the present invention. Furthermore, those of ordinary skill in the art will appreciate that the foregoing description is by way of example only and is not intended to limit the invention. Thus, it is intended that the present subject matter covers such modifications and variations. ,CLAIMS:We claim:
1. A bi-polar metal plate for a fuel cell stack, the bi-polar metal plate comprising:
a first side being adapted to have a first set of predefined channels; and
a second side being adapted to have a second set of predefined channels,
wherein the first set of predefined channels on the first side of bi-polar metal plate being adapted to provide a first flow field for a first reactant, and the second set of predefined channels on the second side of the bi-polar metal plate being adapted to provide a second flow field for a second reactant,
one or more first channels of the first set of predefined channels terminating at a first inlet/outlet on the first side of bi-polar metal plate being adapted to have a first bypass flow field to maintain the one or more first channels active, and
one or more second channels of the second set of predefined channels terminating at a second inlet/outlet on the second side of the bi-polar metal plate being adapted to have a second bypass flow field to maintain the one or more second channels active.

2. The bi-polar metal plate as claimed in claim 1, wherein the first reactant is one of an anode and a cathode and the second reactant is one of the anode and the cathode.

3. The bi-polar metal plate as claimed in claim 1 further comprising an underpass flow field formed by at least one of
one or more teeth protrusions on the first side of the bi-polar metal plates to enable flowing of coolant; and
variation in height of ridges of a first flow field and a second flow field on the first side and the second side of the bi-polar metal plate.

4. A fuel cell stack comprising:
a plurality of bi-polar metal plates placed parallel to each other, wherein each plate of the plurality of bi-polar metal plates includes a first set of predefined channels on a first side and a second set of predefined channels on a second side;
a plurality of supporting plates, wherein each supporting plate positioned between two bi-polar metal plates of the plurality of bi-polar metal plates, wherein each supporting plate comprises a first bend along a flow direction and a second bend perpendicular to the flow direction to avoid cross flow of a second reactant from the second side to the first side;
a plurality of membrane electrode assembly (MEA), wherein each MEA positioned between the two bi-polar metal plates of the plurality of bi-polar metal plates; and
a plurality of gaskets, wherein each gasket positioned on the first side and the second side of each plate of the plurality of bi-polar metal plates, wherein each gasket comprises a plurality of protrusions on one side and a plurality of indentations on another side at regular intervals.

5. The fuel cell stack as claimed in claim 4, wherein the first set of predefined channels on the first side of each plate is adapted to provide a first flow field for a first reactant, and the second set of predefined channels on the second side of each plate is adapted to provide a second flow field for the second reactant.

6. The fuel cell stack as claimed in claim 4, wherein one or more first channels of the first set of predefined channels terminating at a first inlet/outlet on the first side of each plate is adapted to have a first bypass flow field to maintain the one or more first channels active,
wherein one or more second channels of the second set of predefined channels terminating at a second inlet/outlet on the second side of each plate is adapted to have a second bypass flow field to maintain the one or more second channels active.

7. The fuel cell stack as claimed in claim 4 further comprising an underpass flow field to balance pressure on a pair of bi-polar metal plates of the plurality of bi-polar plates and provide cooling effect to the pair of bi-polar metal plates.

8. The fuel cell stack as claimed in claim 7, wherein the underpass flow field is achieved by at least one of
one or more teeth protrusions on the first side of each plate of the bi-polar metal plates to enable flowing of coolant in between the pair of bi-polar metal plates; and
variation in height of ridges of a second flow field and a first flow field between the pair of bi-polar metal plates.

9. The fuel cell stack as claimed in claim 4, wherein each gasket of the plurality of gasket is integrated with one or more stiffeners to give stiffness and eliminate cross flow of a first reactant and the second reactant.

10. The fuel cell stack as claimed in claim 5, wherein the first reactant is one of an anode and a cathode and the second reactant is one of the anode and the cathode.

11. A method for constructing a fuel cell comprising an anode and a cathode on either side of a bi-polar metal plate, the method comprising:
creating an impression on a first side of a pair of bi-polar metal plates to form a first set of predefined channels on the first side and a second set of predefined channels on a second side of the pair of bi-polar metal plates;
positioning a supporting plate on the second side of a first bi-polar metal plate of the pair of bi-polar metal plates, wherein the supporting plate comprises a first bend along a flow direction and a second bend perpendicular to the flow direction for avoiding cross flow of a second reactant from the second side to the first side;
positioning a membrane electrode assembly (MEA) between the pair of bi-polar metal plates; and
positioning a gasket on the first side and the second side of each bi-polar metal plate of the pair of bi-polar metal plates, wherein the gasket comprises a plurality of protrusions on one side and a plurality of indentations on another side at regular intervals for attaching with each plate of the pair of bi-polar metal plates.

12. The method as claimed in claim 11 further comprising:
creating a first bypass flow field on the first side for maintaining one or more first channels of the first set of predefined channels active; and
creating a second bypass flow field on the second side for maintaining one or more second channels of the second set of predefined channels active.

13. The method as claimed in claim 11 further comprising:
creating an underpass flow field for balancing pressure in each plate of the pair of bi-polar metal plates by at least one of:
one or more teeth protrusions on the first side of each plate of the bi-polar metal plates to enable flowing of coolant in between the pair of bi-polar metal plates; and
variation in height of ridges of a second flow field and a first flow field between the pair of bi-polar metal plates.