FIELD OF THE INVENTION

The present invention relates to coolant manifold in PEM fuel cell stack formed by plurality of stacked fuel cells so as to distribute and collect the coolant across the fuel cell stack, more particularly it relates to coolant manifolds in PEM fuel cell stacks with interdigitated flow field designs for water removal.

BACKGROUND OF THE INVENTION

Proton Exchange Membrane Fuel Cells are said to be the best type of fuel cell as the vehicular power source to eventually replace the gasoline and diesel internal combustion engines. Compared to other electrolytes, they operate at very low temperatures of about 800 C allowing rapid start-up. The efficiency of a PEM unit usually reaches between 40 to 60% and the output of the system can be varied to meet shifting demand pattern.. It has drawn most of the attention because of its simplicity, low operating temperature, quick start-up, high efficiency, high energy density and viability over other fuel cell technologies [1].

The by-products of a typical fuel cell system are water and heat. During the normal operation of a PEM fuel cell, liquid water forms at the cathode side of the fuel cell as a result of electrochemical reaction, and also due to the transfer of water from anode to cathode through the electrolyte membrane via electroosmotic effect. Inadequate removal of so formed water causes a condition called flooding in the fuel cell, in which water remains on the cathode electrode surface and blocks the dispersion of oxidizing gas onto the cathode surface. Water flooding will make the PEM fuel cell performance unreliable and unpredictable even under identical operating conditions [2]. Heat management is also an important issue due to the fact that PEM fuel cells need to be operated at specified temperature range that is heat generated as a by-product of the electrochemical reaction need to be removed and the heat generation is non-uniform [3]. Dynamic water balance and heat management are the important challenges for PEM fuel cell stack design and operation.

PRIOR ART

The most conventionally used methods are using a cooling manifold across the fuel cell stack with coolant at the edge of the active area, flowing the coolant between the fuel cells, cooling with phase change [1]. Still another conventional method is to use appropriate design of flow channels on the flow field plates or bipolar plates [2].

US6686084 titled "Gas Block Mechanism for water removal in fuel cells" proposes a conventional method for water management wherein, the accumulated water is directed away from the cathode using capillaries incorporated in it or by using hydrophobic materials such as Teflon in cathode incorporated in it, or by using meshes or screens within the cathode to transfer liquid water away from the catalyst layer.

US5804326 entitled "Integrated reactant and coolant fluid flow field layer for an electrochemical fuel cell" proposed a flow field plate design, which consists of both reactant gas flow field and coolant flow field on the same plate surfaces. Here, each of the separator layers comprises one or more reactant stream passages in fluid communication with one of the electrodes. At least one of the separator layers further comprises one or more coolant stream passages which do not superpose the electrochemically active area of the adjacent membrane electrode assembly, and are fluidly isolated from the reactant stream passages.

US5945232 entitled "PEM-type fuel cell assembly having multiple parallel fuel cell sub-stacks employing shared fluid flow plate assemblies and shared membrane electrode assemblies" describes another integrated bipolar plate design comprising of a flow field assembly, subdivided into multiple fluid flow sub-plates and each sub-plate is having its own reactant flow field design and a cooling flow field is positioned around each of the fluid flow sub-plates. But these designs cause non-uniform temperature distribution across the fuel cell stack [4].

US7745032, US 6686084, US6503653, US2001/0004501 and US5641586 describes the state-of-art wherein, the interdigitated flow field design has dead-end flow channel configuration which creates the pressure drop between flow inlet and flow outlet; to force the reactants gases to flow through the gas diffusion layer for the convection transport and thus improves the efficiency of the fuel cell.

A number of fuel cells are required to be stacked to get voltages useful for practical applications. US 6686084, US5853909 and US5840414 describes that a conventional fuel cell system may require a cooling plate for every fuel cell. The use of number of cooling plates increases the weight, volume and cost of the fuel cell stack.

US6686084, US 5853909, US 5840414 and US 2007/0218332 proposes that the cooling manifolds with cooler plates increases the weight of the fuel cell stack and thus decreases its efficiency. In contrast to this, US 5804326 and US 5945232 proposes that the cooling manifolds formed without the use of cooler plates suffer with the problem of water flooding.

Therefore, there is a need for an apparatus and method for efficient heat and water management which eliminates all the problems associated with fuel cell stack operation and satisfies all the above mentioned requirements. The advantages of the present invention includes mechanisms to maintain membrane hydration and uniform temperature distribution over the electrode surface; to prevent water flooding on cathode side; to eliminate separate cooling plate for each fuel cell and thus to improve the stack power density.

The novel aspects of the invention are that the cooling manifold provided is common for integrated cooling flow fields on both anode and cathode sides, in fluid communication which can maintain uniform temperature distribution across the fuel cell stack by removing the excess heat produced during the electrochemical reaction and eliminates the use separate cooling plates in PEM fuel cell stack; cooling flow fields are positioned in-between and around both the anode and cathode gas flow fields; the integrated cathode flow field assembly includes two symmetrical sets of interdigitated flow configuration with separate inlet and outlets for each set uniform distribution of reaction products or water across the flow field design in which the liquid water from porous gas block
medium of each set is in fluid communication with cathode side coolant flow field; the integrated anode flow field design includes a common inlet at centre of the flow field plate (bipolar plate) which is communication with all the four flow sectors of anode flow field design which provides centrally symmetric uniform distribution of reactants across the entire flow field plate without any stagnant areas and channeling, low concentration drop, and low pressure drop. Thus the described flow field design can remove water effectively and reduces water flooding. This design also provides convention transport of the reactants thus improving the efficiency of the system. The other features and advantages of the present invention will become more apparent with reference to the following description of the drawings and appended claims.

SUMMARY

The present invention relates to coolant manifold in proton exchange membrane fuel cell, using hydrogen gas as the fuel and oxygen gas as oxidant. In one of the embodiments of the present invention; a coolant manifold for distributing and collecting the coolant across all the fuel cells of the stack is formed by a plurality of stacked cells with a common inlet and a common outlet for all the fuel cells in the system. The coolant manifold (comprised of two chambers, one for discharging and the other for collecting the coolant) is installed by aligning the central axis of the inlet and outlets of the coolant flow field for all the fuel cells of the system. The coolant manifold distributes the coolant to the coolant flow fields on both sides of each and every flow field plate or bipolar plate (i.e. around both anode and cathode side flow field designs).

In another aspect of the present invention, there is an integrated cathode plate assembly consists of two individual sets of interdigitated flow field design which are symmetrical to each other and a coolant flow field placed in-between and around the cathode gas interdigitated flow field design. Each set of interdigitated flow field design includes a major surface with feed side interdigitated flow channels and discharge side interdigitated channels arranged in an interdigitated configuration allows the flow of cathode gas from feed side channels to discharge side channels. A number of porous gas block mediums are placed in adjacent to the feed side flow field channels and the porosity of the gas blocks is such that the liquid water flows through the porous gas block medium with cathode gas remain blocked from flowing through the medium. The cathode side gas block medium is in fluid communication with coolant manifold. The gas block medium of one set is in communication with inlet (discharge) chamber of the manifold and the other set is in communication with outlet (collecting) chamber of the manifold. The inlet chamber of the cooling manifold is further in communication with two flow channels of the cooling flow field on the cathode surface and the cooling flow field (integrated with cathode gas flow field) is positioned in-between and around both the sets. The coolant flows through the prescribed design and ejects out of the design through the outlet chamber of the cooling manifold.

Another aspect of the present invention comprises of an integrated anode plate flow field design with a common flow inlet (for all the flow sectors of the anode flow field design at the centre of the flow field plate) for effective supply of gaseous fuel to all the flow field sectors and also includes an outlet (at the periphery/corner of the rectangular anode gas flow field design) for each sector for effective collection of reactants/reaction products for the fuel cell operation. The fuel gas flow through each sector in a plurality of passes and each flow sector includes a plurality of sets, each set containing plurality of flow channels connected in straight and parallel pattern. The sets of the each flow sector are connected in serial flow pattern. The number of sets is same for all sectors. The four sectors are symmetrical with each other across the common inlet at the centre of the flow field design and flow field plate (bipolar plate). The inlet chamber of the coolant manifold is in communication with two flow channels of the coolant flow field (integrated with anode gas flow field), and is positioned in-between and around each of the flow field sectors. The coolant coming from the coolant flow field is in communication with the outlet chamber of the cooling manifold.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 illustrates an exploded view of two cell PEM fuel cell stack with all the embodiments of the present invention;

Figure 2A illustrates a plan view of cathode flow field assembly with respect to embodiments of die present invention;

Figure 2B illustrates an isometric view of cathode flow field assembly of the present invention across the section EE';

Figure 3A illustrates a plan view of anode flow field design with respect to embodiments of the present invention;

Figure 3B illustrates an enlarged view of a flow sector of anode flow field design to the present invention;

Figure 4 illustrates a plan view of proton exchange membrane (PEM) with some aspects of the present invention;

Figure 5 illustrates a plan view of the gasket with embodiments of the invention;

Figure 6A illustrates an isometric view of ten cell PEM fuel cell stack with alt the embodiments of the present invention; and

Figure 6B illustrates an isometric view often cell PEM fuel cell stack across the section UVWXYZ with all the embodiments of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Descriptions of various embodiments of the present invention are made in referent to the accompanying drawings, and are shown by way of illustration in which the invention may be practiced. The following description is only for the sake of understanding and is not intended to limit the present invention. By adding or utilizing other embodiments and structural or dimensional changes may be done without eliminating the scope of present invention.

Figure I includes a flow field plate or bipolar plate 1 of present invention, pair of membrane-electrode assemblies (MEAs) 4, 5 on both sides of the flow field plate 1, gaskets 2, 6 on both sides of MEA 4, gaskets 3, 7 on both sides of MEA 5 and end contact plates 8, 9 adjacent to gaskets 6, 7, respectively. The flow field plate is made up of electrically conducting material such as graphite, carbon composites, or a metal coated with corrosion resistant material.

The flow field plate or bipolar plate 1, MEAs 4, 5, gaskets 2, 3, 6, 7 and end contact elements 8, 9 are stacked together between two end plates 10, 11. Non-conductive gaskets 2, 3, 6, 7 may be used to provide sealing and electrical insulation between the components of the fuel cell stack and also to hold or position the MEA assemblies 4, 5 in alignment with the flow field embodiments of the present invention.

The MEAs 4, 5 typically include proton exchange membranes 4B, 5B formed by a perfluorocarbon-sulfonic acid ionomer (PSA polymer) such as Nafion® (a specific PEM registered to Dupont), platinum/carbon catalyzed electrodes 4A, 4C, and 5A, 5C on either sides of proton exchange membranes 4B, 5B, respectively, gas diffusion layers (made of carbon fibers or carbon cloth) 4D, 4E and 5D, 5E are placed adjacent to cathode 4A, 5A and anode 4C, 5C layers. The fuel gas (typically H2 gas for PEM fuel cells) is supplied to gas diffusion layers 4E, 5E of MEAs 4, 5, electrochemical reaction of hydrogen oxidation occurs at the interface between catalyst impregnated anode layers 4C, 5C and proton exchange membranes 4B, 5B to produce hydrogen ions (protons) and electrons. The so formed electrons are forced to travel through an external circuit in the form of electrical current. The protons pass through polymer electrolyte membrane 4B, 5B to the cathode side interface, between catalyst loaded cathode layers 4A, 5A and proton exchange membranes 4B, 5B where they react exothermically with electrons transferred from external circuit and oxygen gas supplied on cathode side 4A, 5A to produce water. The number of cells in series determines the maximum stack voltage and the active area of each cell limits the maximum current that may be derived from the fuel cell stack.

Figure 2A shows a plan view of one of the aspects of the present invention i.e. cathode flow field assembly 32 on flow field plate or bipolar plate 1 consisting of two sets of interdigitated flow field design 13, 14 with separate inlets 15, 16 and outlets 17, 18 and 19,20 for the sets 13,14, respectively. The sets 13, 14 are symmetrical about the axis EE' with 1800 rotation. The cathode gas flows through the interdigitated flow field 21 A, 21B of sets 13,14 and the flow fields 21 A, 21B of each set 13,14 are in communication with flow field inlets 15, 16, respectively, which are further in communication with cathode gas inlet flow chambers (not shown in Figure 2A). The flow field inlets 15,16 are located at the opposite corners of the cathode flow field assembly 32 as well as flow field plate or bipolar plate 1.

A number of feed side interdigitated channels 22A, 22B are extended and fluid communication with feed side internal plenum 23A, 23B and these feed side interdigitated channels 22A, 22B have dead-end terminals 24A, 24B for sets 13, 14, respectively. In another embodiment of the interdigitated flow field design, there is an array of feed side interdigitated channels 22A, 22B that are perpendicular to the feed side internal plenum 23A, 23B, respectively. Adjacent and/or in between the feed side interdigitated channels 22A, 22B there are exhaust side interdigitated channels 25A, 25B, respectively, where the cathode gas flows along the same direction as that of fees side interdigitated channels 22A, 22B. The feed side interdigitated channels 22A, 22B are substantially parallel with exhaust side interdigitated channels 25A, 25B. The exhaust side interdigitated channels 25A, 25B have terminal ends 26A, 26B and they are extended and in communication with exhaust side internal plenum 27A, 27B which are further in communication with exhaust side cathode gas outlets 18,20 respectively.

The ribs or lands between the feed side interdigitated channels 22A, 22B and exhaust side interdigitated channels 25A, 25B is referred as the lands between interdigitated channels 28A, 28B. The convective diffusion of cathode gas over the lands 28A, 28B from feed side interdigitated channels 22A, 22B to exhaust side interdigitated channels 25A, 25B is through the gas diffusion layer (not shown in Figure 2A).

The interdigitated flow configuration results in high pressure drop between feed side interdigitated channels 22A, 22B and exhaust side interdigitated channels 25A, 25B which causes the cathode gas to convective transfer 29A, 29B through the cathode side gas diffusion layer. A porous gas block medium 30A, 30B is inserted into the cathode side of the flow field plate or bipolar plate 1 adjacent to the feed side interdigitated channels 22A, 22B. The other embodiments related to gas block medium 30A, 30B made of graphite, sintered metals, glass fibers, resin fibers and combination of any of these with binding resin, are explained in detail in the description of Figure 2B. The porous gas block medium 30A, 30B is in communication with inlet 17 and outlet 19, respectively; of the cathode side coolant flow field 31 integrated to interdigitated flow field designs 13, 14. The integrated coolant flow field 31 is positioned in-between and around the two sets of interdigitated flow field design 13, 14 and common inlet 36 for anode gas flow field design 37.

Figure 2B shows an isometric view of cathode flow field assembly with embodiments of the present invention across the section EE'. The embodiments related to anode side flow field 35 assembly 35 are excluded in Figure 2B. The liquid water produced or condensed on cathode side feed interdigitated channels 22A sipped off through the porous gas block medium 30A to the cathode side coolant flow field 31 inlet 17. The liquid water flow from feed side interdigitated flow channels 22A to porous gas block medium 30A is represented by 33A. The gas block medium 30A is positioned into the cathode side base plate to provide means of porous medium for the flow 34A of liquid water from porous gas block medium to cooling flow field inlet 17 which is in further communication with coolant inlet flow chamber 57 (not shown in Figure 2B)

Figure 3A depicts plan view of anode flow field assembly 35, having a common inlet or opening 36 (for the anode gas flow field design 37) which is in communication to four symmetrical sectors 38A, 38B, 38C, 38D. This embodiment directs the anode gas towards flow ribs 44A, 44B, 44C, 44D of the upstream sets 39A, 39B, 39C, 39D for effective reactant distribution. The openings 45A, 45B, 45C, 45D at corners/periphery of the anode gas flow field couple the outlet manifolds for the reactant gases/produces from anode side flow sectors 38A, 38B, 38C, 38D, respectively. The reactant gas concentration variation is same and symmetrical for all the sectors 38A, 38B, 38C, 38D, since the flow sectors share equal amount of active surface area. The effective flow length 46A, 46B, 46C, 46D from the flow inlet 36 to outlets 45A, 45B, 45C, 45D is same and symmetrical from the flow inlet to outlet for all the sectors 38A, 38B, 38C, 38D, which incorporates equal and symmetrical pressure drop variation across all the flow sectors 38A, 38B, 38C, 38D. The anode side coolant flow field design 51 with inlet 17 and outlet 19 is placed in-between and around the anode gas flow field design 37 as shown in Figure 3A (i.e. the anode side coolant flow field design 51 is integrated with gas flow field design 37). The flow channels for reactant flow fields and for coolant flow fields 31,51 are of square type cross section (1 mm x 1 mm). The porous gas block medium 30A, 30B placed adjacent to feed side interdigitated flow channels 22A, 22B positioned into the cathode side base plate with cross section dimensions 1 mm x 1.25 mm.

Figure 3B shows enlarged view of flow sector 38A of the anode gas flow field design 37. The flow sector 38A is composed of five sets 39A, 40A, 41 A, 42A, 43A; each set containing two flow channels 45A', 46A' formed by one flow rib 44A and the flow channels 45A', 46A' are connected in straight and parallel pattern. The five sets 39A, 40A, 41 A, 42A, 43A of the flow sector 38A are connected in serial flow pattern. All the consecutive pairs of sets of the sector are connected through interconnecting channels 47A, 48A, 49A, 50A. All the flow sectors are symmetrical in accordance to their flow arrangement formed by the flow channels 45A', 46'i interconnecting channels 47A, 48A, 49A, 50A, flow ribs 44A, 44B, 44C, 44D etc.

The plan view of proton exchange membrane (PEM) 4B5 5Bp platinum catalyzed carbon cathode 4A, 5A, and anode 4C, 5C layer,, cathode and anode side gad diffusion layers 4D, 5D and 4E, 5E is depicted in Figure 4, the dimensions of PEM are such that the anode gas flow field 37 and cathode gas flow fields 13, 14 arc covered totally and eliminating the use of PEM over both cathode cooling flow field desig31 (show Figure 2A) and anode cooling flow field design 51 (shown in Figure 3A.. The openin366 is made to provide means for anode gas inlet manifold (not shown here) to supply anode gas to anode flow field design 37. The dimensions for branches of proton exchange membrane (PEM) 52, 53 are such that, PEM shall cover the anode flow field desig377 and cathode flow field designs 13, 14 (two sets of interdigitated flow field design) with an excess offset of I mm to provide means to incorporate in between the gaskets 2, 6 and 3, 7 for MEAs 4, 5(refer Figure 5), respectively.

Figured depicts the plan view of gasket 2, 3, 6, 7 used to hold the MEAs 4, 5t to prevent the mixing of reactant gases with each other, and to avoid the leakage of gases from fuel cells. The dimensions of the openings 54, 55 should be such that they cover the anode flow field design 37 and cathode flow field designs 13, 14. The other openings for cathode gas inlets 15, 16, cathode gas outlets 18, 20, coolant flow field design inlet 17 and coolant flow field design outlet 19, common anode gas inlet 36, anode gas outlets 45A, 45B, ,5C, 45D are given to provide means for their respective manifolds.

Figure 6A is an isometric view of ten cell PEM fuel cell stack 56 with all the embodiments of the present invention. The anode gas outlet manifolds 60A 60B 60C 60D corresponding to anode gas outlets 45A, 45B, 45C, 45D, cathode gas inlet manifolds 61, 62 corresponding to anode gas inlets 15, 16, and cathode gas outlet manifolds 63, 64 corresponding to anode gas outlets 18, 20 are also shown.

Figure 6B depicts an isometric view often cell stack across the section UVWXYZ with all the embodiments of the present invention, to show the inlet and outlet chambers of cooling manifold 57, 58. The common anode gas inlet manifold 59 corresponding to the anode gas flow field design 37 is also shown.

REFERENCES

1. Barbir, F. PEMFuel Cells: Theory and Practice, Elsevier Academic Press, New York., 2005.

2. Li, XL, Sabir, I. and Park, J., Journal of Power Sources, 163 (2007), 933-942.

3. Matamoros, L. and Briiggemann, D., Journal of Power Sources, 161 (2006), 203-213.

4. Li, Xi. and Sabir, 1., International Journal of Hydrogen Energy, 30 (2005), 359-371. preliminary.

WE CLAIM:

1. A coolant manifold integrated in a flow filed plate for a Proton Exchange
Membrane cell fuel stack used in a vehicle characterized with uniform membrane
hydration, temperature distribution and devoid of water flooding comprising of:

(a) An integrated cathode flow field assembly 32 on flow field plate 1 including two symmetrical sets of interdigitated flow configuration 13, 14 with separate inlets 15,16 and outlets 17,18 and 19 , 20 for the sets 13,14 respectively, and a porous gas block medium 30A, 30B for each set; and

(b) An integrated anode flow field design assembly 35 includes a common inlet 36 at the centre of the plate in communication with plurality of symmetrical sectors 38A, 38B, 38C, 38D; each sector having outlets 45A, 45B, 45C, 45D at the periphery for all the sectors 38A, 38B, 38C, 38D; and an internally integrated coolant design 51.

2. The coolant manifold integrated in a flow field plate as in claim 1 wherein, two symmetrical sets 13 and 14 of the cathode flow field assembly comprising of plurality of interdigitated flow field 21 A, 21B are in communication with flow field inlets 15,16 respectively.

3. The coolant manifold integrated in a flow field plate as in claim 1 wherein, the inlets 15, 16 are located at the opposite corners of the cathode flow assembly 32 as well as flow field plate 1.

4. The coolant manifold integrated in a flow field plate as in claim 1 wherein, two symmetrical sets 13 and 14 of the cathode flow field assembly further comprising of plurality of feed side interdigitated flow field channels 22A, 22B; exhaust side interdigitated channels 25A, 25B; the said exhaust side interdigitated channels having terminal ends 26A, 26B.

5. The coolant manifold integrated in a flow field plate as in claim 5 wherein, feed side interdigitated flow field channels 22A, 22B and exhaust side interdigitated channels 25A, 25B are extended and fluid communication with feed side internal plenum 23A, 23B and exhaust side internal plenum 27A, 27B respectively.

6. The coolant manifold integrated in a flow field plate as in claim 5 wherein, the ribs or land between feed side interdigitated flow field channels 22A, 22B and exhaust side interdigitated channels 25A, 25B is referred as the lands between interdigitated cannels 28A, 28B and convective diffusion of cathode gas over these lands is through the gas diffusion layer.

7. The coolant manifold integrated in a flow field plate as in claim 1 wherein, the gas block medium of the cathode flow field assembly is made of graphite, sintered metals, glass fibers, resin fibers and combination of any of these with binding resin.

8. The coolant manifold integrated in a flow field plate as in claim 1 wherein, the porous gas block medium 30A and 30B of the cathode flow field assembly is in communication with the inlet 17 and outlet 19, respectively.

9. The coolant manifold integrated in a flow field plate as in claim 1 wherein the anode flow field assembly includes four symmetrical sectors 3 8A, 38B, 38C and 38D whose reactant gas concentration variation is same and symmetrical.

10. The coolant manifold integrated in a flow field plate as in claim 1 wherein, anode flow field assembly has a common inlet or opening 36 which is in communication to four symmetrical sectors 3 8A, 38B, 38C, 38D which directs the anode gas towards flow ribs 44A, 44B, 44C, 44D of the upstream sets 39A, 39B, 39C, 39D for effective reactant distribution.

11. The coolant manifold integrated in a flow field plate as in claim 1 wherein, anode flow field assembly has an outlets 45A, 45B, 45C, 45D at corners/periphery and couple the outlet manifolds for the reactant gases/products from anode side flow sectors 38A, 38B, 38C, 38D respectively.

12. The coolant manifold integrated in a flow field plate as in claim 1 wherein, anode flow field assembly has an anode side coolant flow field design 51 with inlet 17 and outlet 19 is placed in-between and around anode gas flow field design 37.

13. The coolant manifold integrated in a flow field plate as in claim 1 wherein, anode gas flow field design has a flow sector 38A is composed of five sets 39A, 40A, 41 A, 42A, 43A and are connected in serial parallel pattern.

14. The coolant manifold integrated in a flow field plate as in claim 1 wherein, each set of the flow sector connected in straight and parallel pattern in the anode flow field design assembly comprising two flow channels 45A\ 46Av formed by one flow rib 44A.

15. The coolant manifold integrated in a flow field plate as in claim 1 wherein, all the consecutive pairs of sets of the sector are connected through interconnecting channels 47A, 48A, 49A, 50A.

16. The coolant manifold integrated in a flow filed plate as in claim 1 where it is integrated in a fuel cell stack 16 which includes a pair of membrane-electrode assemblies 2, 3 on both sides of the flow field plate 1; end contact elements 4, 5 adjacent to membrane electrode assemblies 4, 5 stacked between two end plates 6, 7; and non-conductive gaskets 8,9,10 & 11 placed above and below each flow field plate for sealing any gas leakage.

17. The coolant manifold integrated in a flow field plate as in claim 1 wherein the fuel cell stack is integrated in a two-wheeler.