[0001] The present subject matter relates to fuel cells, and in particular,
to heating of fuel cells.
> BACKGROUND
[0002] Fuel cells convert chemical energy into electric power. The
fuel cell produces electricity from a chemical reaction between a fuel and an oxidant. Some fuel cells, such as High Temperature Polymer Electrolyte fuel cells (HTPEM-FC), operate at a temperature between 80° C and 150° C. Such ) fuel cells start producing electric power when heated to above-mentioned temperature.
BRIEF DESCRIPTION OF DRAWINGS
[0003] The detailed description is provided with reference to the
accompanying figures. In the figures, the left-most digit(s) of a reference
> number identifies the figure in which the reference number first appears. The
same numbers are used throughout the drawings to reference like features
and components.
[0004] Fig. 1 illustrates a perspective view of a plate assembly, in
accordance with an implementation of the present subject matter;
) [0005] Fig. 2 illustrates an exploded view of the plate assembly, in
accordance with an implementation of the present subject matter;
[0006] Fig. 3 illustrates an exploded view of the plate assembly, in
accordance with an implementation of the present subject matter;
[0007] Fig. 4 illustrates a sectional view of the plate assembly, in
> accordance with an implementation of the present subject matter; and
[0008] Fig. 5 illustrates a block diagram of a fuel cell stack, in
accordance with an implementation of the present subject matter.

[0009] A fuel cell stack may comprise a plurality of fuel cells. Each
fuel cell may comprise an anode, where fuel may undergo an oxidation reaction, and a cathode, where an oxidant may undergo a reduction reaction.
i The fuel may be, for example, hydrogen and the oxidant may be, for example, air. The anode and the cathode may have a catalyst, such as Platinum (Pt) catalyst. In an example, the anode and the cathode may be part of a membrane electrode assembly (MEA). The MEA may comprise a conducting medium, such as a polymer electrolyte membrane (PEM) positioned between
i the anode and the cathode. The PEM conducts the hydrogen ions released from the anode as a result of the oxidation reaction to reach the cathode and prevents the electrons from the anode to pass through the PEM.
[0010] If the fuel has carbon monoxide (CO), the Pt catalyst may get
contaminated, leading to prevention of chemical reactions at the anode and
i at the cathode after a period of time. The contamination of the anode and the cathode by CO may be reduced at elevated temperatures of the fuel cell stack, such as temperatures in the range of 80°C to 150°C. Hence, in some fuel cells, such as High Temperature Polymer Electrolyte fuel cells (HTPEM-FC), the operating temperatures are generally maintained in the temperature
i range of 80° C to 150°C. In particular, the MEA of such fuel cells may have to be heated quickly and be maintained at the temperature range of 80° C to 150°C for starting of chemical reactions of the fuel cells and continuous operation of such fuel cells.
[0011] The heating of fuel cells of the fuel cell stack may be an
i energy-consuming and a time-consuming process, for example, due to the presence of poor heat-conducting components in the fuel cell. For instance, in some cases, a heating pad is used to heat the fuel cells. One or more heating pads may be disposed on sides of the fuel cell stack for heating the fuel cells. However, due to thermal losses at ends of the fuel cell stack, the i use of heating pad may result in slow heating of the fuel cells. Further, heat

generated by such heating pads may be transferred not only to the MEA, but also to the complete fuel cell structure including components, such as casing, fasteners, and the like. Thus, such a heat transfer may reduce the efficiency of the heating process and may cause failure of such components.
[0012] In order to heat the MEA quickly and to speed up the process
of starting the chemical reactions in the fuel cell, the heating process may have to be improved. In this regard, in some cases, the MEA may be heated by fixing heating coil in flow field plates, such as an anode flow field plate and a cathode flow field plate, of fuel cells. The anode flow field plate and the cathode flow field plate may include flow channels which may act as pathway for the fuel and oxidant respectively. The heating coil is fixed around the flow field area. The fixing of heating coil around the flow channels gives rise to a non-uniform temperature distribution across the MEA. The non-uniform temperature distribution in the MEA may affect the performance of the fuel cells. For instance, the non-uniform temperature distribution across the MEA may give rise to poor utilization of reactants in the fuel cell, resulting in poor performance of the fuel cell.
[0013] The present subject matter relates to heating of fuel cells.
With the implementations of present subject matter, heating of the fuel cells to an elevated temperature, such as temperatures from 80° C to 150° C, may be achieved in a reduced time span and in an efficient manner.
[0014] In accordance with an example implementation, a fuel cell
stack may comprise a plurality of fuel cells. The fuel cell stack may comprise a plate assembly. The plate assembly may comprise a cathode flow field plate and an anode flow field plate. The cathode flow field plate may be part of a first fuel cell of the fuel cell stack and may supply oxidant to a cathode of the first fuel cell. The cathode flow field plate may have a first cathode surface and a second cathode surface. The anode flow field plate may be part of a second fuel cell and may supply fuel to an anode of the second fuel cell. The anode flow field plate may have a first anode surface and a second anode

surface. In an example, the first anode surface may face and may be in contact with the first cathode surface.
[0015] The plate assembly may comprise a heating element. The
heating element may be positioned in a first groove of a first grooved surface. The first grooved surface may be either the first anode surface or the first cathode surface. When supplied with electric current, the heating element may heat the first fuel cell and the second fuel cell. For instance, the heating element may heat the cathode flow field plate and the anode flow field plate and in turn, heat the first fuel cell and the second fuel cell.
[0016] The present subject matter facilitates an efficient and quick
heating of the fuel cells. For instance, since the plate assembly comprises the heating element, the present subject matter facilitates heating of the fuel cells to elevated temperatures in a reduced time span. This, in turn, decreases the starting time of the fuel cells. Further, the present subject matter may achieve a uniform temperature distribution across the electrodes of the fuel cell. Consequently, the present subject matter may enhance the performance of the fuel cells.
[0017] The present subject matter is further described with reference
to Figs. 1-5. It should be noted that the description and figures merely illustrate principles of the present subject matter. Various arrangements may be devised that, although not explicitly described or shown herein, encompass the principles of the present subject matter. Moreover, all statements herein reciting principles, aspects, and examples of the present subject matter, as well as specific examples thereof, are intended to encompass equivalents thereof.
[0018] Fig. 1 illustrates a perspective view of a plate assembly 100,
in accordance with an implementation of the present subject matter.
[0019] The plate assembly 100 may comprise an anode flow field
plate 102 to supply fuel to an anode (not shown in Fig. 1) and a cathode flow

field plate 104 to supply oxidant to a cathode (not shown in Fig. 1). In an example, the anode flow field plate 102 and the cathode flow field plate 104 may be made of graphite.
[0020] The anode flow field plate 102 and the cathode flow field plate
104 may face each other and may contact each other. For instance, a first anode surface (not shown in Fig. 1) of the anode flow field plate 102 and a first cathode surface (not shown in Fig. 1) of the cathode flow field plate 104 may face each other and may be in contact with each other. In an example, the first cathode surface may cover the entire first anode surface and vice-versa.
[0021] The anode flow field plate 102 may have a second anode
surface 106 behind/rear side of the first anode surface. Similarly, the cathode flow field plate 104 may have a second cathode surface (not shown in Fig. 1) behind/rear side of the first cathode surface.
[0022] The anode flow field plate 102 may have a first plurality of flow
channels 108 on the second anode surface 106 to facilitate fuel flow. That is, the first plurality of flow channels 108 may act as a pathway for the fuel to reach the anode. In an example, the anode may be positioned in proximity of the second anode surface 106. Similarly, the cathode flow field plate 104 may comprise a second plurality of flow channels 110 positioned on the second cathode surface to facilitate oxidant flow. That is, the second plurality of flow channels 110 may act as a pathway for the oxidant to reach the cathode. The cathode may be positioned in proximity of the second cathode surface.
[0023] The plate assembly 100 may further comprise a heating
element 112 to heat the anode flow field plate 102 and the cathode flow field plate 104. The heating element 112 may be sandwiched between the anode flow field plate 102 and the cathode flow field plate 104. For instance, the heating element 112 may be positioned between the first anode surface and the first cathode surface.

[0024] In an example, to position the heating element 112 between
the first anode surface and the first cathode surface, a first groove (not shown in Fig. 1) may be provided on one of the two surfaces. The surface on which the first groove is provided (which is either the first anode surface or the first
i cathode surface) may also be referred to as a first grooved surface. In addition to the first groove on the first surface, a second groove (not shown in Fig. 1) may be provided on a second grooved surface. If the first grooved surface is the first anode surface, the second grooved surface may be the first cathode surface and if the first grooved surface is the first cathode
i surface, the second grooved surface may be the first anode surface. In the below description, the first grooved surface is explained as the first anode surface and the second grooved surface is explained as the first cathode surface.
[0025] Since the groove, such as the first groove and the second
i groove, is provided on surface behind the surface that has flow channels, the machining of the cathode flow field plate 104 and the anode flow field plate 102 becomes simpler, when compared to techniques where a heating element is positioned in grooves provided on same surface as the flow channels.
i [0026] The heating element 112 may get heated when supplied with
an electric current. The heat of the heating element 112 gets transferred to the anode flow field plate 102 and the cathode flow field plate 104, causing their heating. For instance, the heating of the heating element 112 may cause heating of the first anode surface, the second anode surface 106, the first
i cathode surface, and the second cathode surface. To connect the heating element 112 with a power supply, a portion of the heating element 112 may extend out of the anode flow field plate 102 and the cathode flow field plate 104, as illustrated in Fig. 1.
[0027] In an example, the anode flow field plate 102 and the cathode
i flow field plate 104 may have same dimensions. For instance, the anode flow

field plate 102 may have the same length, breadth, and thickness as the cathode flow field plate 104.
[0028] Further, the anode flow field plate 102 may comprise a first
plurality of openings 114-1, 114-2, 114-3 and 114-4 and the cathode flow field
5 plate 104 may comprise a second plurality of openings (not marked in Fig. 1). A diameter of the first plurality of openings 114-1, 114-2, 114-3 and 114-4 may be same as that of the second plurality of openings. Further, a position of the first plurality of openings 114-1, 114-2, 114-3, 114-4 on the anode flow field plate 102 may be same as a position of the second plurality of openings
D of the cathode flow field plate 104. Accordingly, when the anode flow field plate 102 contacts the cathode flow field plate 104, the first plurality of openings 114 may coincide with the second plurality of openings. The first plurality of openings 114-1, 114-2, 114-3 and 114-4, and the second plurality of openings may facilitate coupling of the anode flow field plate 102 and the
5 cathode flow field plate 104 with other components of a fuel cell stack, such as anodes, cathodes, and other plate assemblies. For instance, the components of the fuel cell stack may have openings similar to that of the first plurality of openings 114 and the second plurality of openings. Fasteners may be inserted into the openings of various components of the fuel cell stack
D to assemble the fuel cell stack.
[0029] Fig. 2 illustrates an exploded view of the plate assembly 100,
in accordance with an implementation of the present subject matter. Here, the second cathode surface 202 of the cathode flow field plate 104 is shown. The second plurality of flow channels 110 on the second cathode surface 202 5 may facilitate supply of the oxidant to the cathode (not shown in Fig. 2). Further, the cathode flow field plate 104 may comprise the second plurality of openings 203-1, 203-2, 203-3, and 203-4 to facilitate coupling with the anode flow field plate 102 and various components of the fuel cell stack (not shown in Fig. 2).

[0030] The anode flow field plate 102 may comprise the first anode
surface 204. As will be understood, the second anode surface 106 (not shown in Fig. 2) is disposed behind the first anode surface 204 in the view illustrated herein. The first anode surface 204 may comprise the first groove 206, and the first anode surface 204 may be referred to as the first grooved surface. The heating element 112 may be positioned in the first groove 206. The first groove 206 may have a shape corresponding to that of the heating element 112. In an example, the heating element 112 and the first groove 206 may be serpentine-shaped.
[0031] A thickness of the anode flow field plate 102, a depth of the
first plurality of flow channels 108, and a depth of the first groove 206 may be chosen such that there is no impression of the first groove 206 on the second anode surface 106 and no impression of the first plurality of flow channels 108 on the first anode surface 204. As an example, the thickness of the anode flow field plate 102 may be greater than a sum of the depth of the first groove 206 and the depth of the first plurality of flow channels 108.
[0032] Although the heating element 112 is explained as being
positioned in a groove 206 in the first anode surface 204, in an example, the heating element 112 may be positioned in a second groove in the first cathode surface (not shown in Fig. 2). In a further example, grooves may be provided on both the first anode surface 204 and the first cathode surface and the heating element 112 may be positioned in both the first groove 206 and the second groove.
[0033] Fig. 3 illustrates an exploded view of the plate assembly 100,
in accordance with an implementation of the present subject matter. Here, the first cathode surface 302 of the cathode flow field plate 104 is shown. The first cathode surface 302 may comprise the second groove 304. As will be understood, the second cathode surface 202 is disposed behind the first cathode surface 302 in the view illustrated herein.

[0034] To avoid an impression of the second groove 304 on the
second cathode surface 202 and to avoid the impression of the second plurality of flow channels 110 on the first cathode surface 302, a thickness of the cathode flow field plate 104, a depth of the second plurality of flow channels 110, and a depth of the second groove 304 may be chosen accordingly. As an example, the thickness of the cathode flow field plate 104 may be greater than a sum of the depth of the second groove 304 and the depth of the second plurality of flow channels 110.
[0035] The heating element 112 may be positioned in the second
groove 304. The second groove 304 may have a shape corresponding to that of the heating element 112. In an example, the second groove 304 may be serpentine-shaped.
[0036] Further, the heating element 112 may provide uniform
distribution of heat across the cathode flow field plate 104. To facilitate this, the heating element 112 may comprise a plurality of vertical sections. The vertical sections include a first vertical section 306-1, a second vertical section 306-2, and one or more vertical sections, such as 306-3, 306-4 between the first vertical section 306-1 and the second vertical section 306-2. Further, the heating element 112 may comprise a plurality of horizontal sections, such as 308-1, 308-2 connecting the vertical sections of the heating element 112. For instance, the horizontal sections 308-1 may connect the first vertical section 306-1 and the vertical section 306-3, the horizontal section 308-2 may connect the vertical section 306-3 and the vertical section 306-4. The horizontal sections may be, for example, arcuate shaped.
[0037] In an example, the second groove 304 may comprise a
plurality of vertical sections to accommodate the vertical sections of the heating element 112. For instance, the vertical sections of the second groove 304 may include a first vertical section 316-1, a second vertical section 316-2 and one or more vertical sections, such as 316-3, 316-4 between the first vertical section 316-1 and the second vertical section 316-2. Further, each of

a plurality of horizontal sections may connect two vertical sections of the second groove 304. For instance, a horizontal section 317-1 may connect the vertical sections 316-1 and 316-3. Each vertical section of the heating element 112 may be accommodated in a corresponding vertical section of the second groove 304 and a horizontal section of the heating element 112 may be accommodated in the corresponding horizontal section of the second groove 304. For instance, the first vertical section 306-1 of the heating element 112 may be positioned in the first vertical section 316-1 of the second groove 304 and the horizontal section 308-1 of the heating element 112 may be accommodated in the horizontal section 317-1 of the second groove 304.
[0038] The vertical sections of the heating element 112 and the
vertical sections of the second groove 304 may be distributed across the first cathode surface 302. For instance, the cathode flow field plate 104 may comprise a first side 320, a second side 322 opposite to the first side 320, a third side 324, and a fourth side 326 opposite to the third side 324. The vertical sections of the heating element 112 and the vertical sections of the second groove 304 may extend between the first side 320 and the second side 322 and along the third side 324 and the fourth side 326. The first vertical section 306-1 of the heating element 112 positioned in the first vertical section 316-1 of the first groove 206 may be closer to the third side 324 than other vertical sections of the heating element 112. The second vertical section 306-2 of the heating element 112 positioned in the second vertical section 316-2 of the second groove 304 may be closer to the fourth side 326 than other vertical sections.
[0039] As the heating element 112 is positioned in the second groove
304, an area of the first cathode surface 302 enclosed between the first vertical section 306-1 of the heating element 112 and the second vertical section 306-2 of the heating element 112 may be greater than remaining area of the first cathode surface 302. For instance, let A (as illustrated by hatched area in Fig. 3) be an area of the first cathode surface 302 enclosed between

the first vertical section 306-1 of the heating element 112 and the second vertical section 306-2 of the heating element 112. The area A may be greater than the remaining area of the first cathode surface 302. This distribution of the heating element 112 may distribute heat uniformly on the cathode flow field plate 104.
[0040] Similar to the cathode flow field plate 104, the heating element
112 may be distributed across the first anode surface 204 (as shown in Fig. 2) and accordingly, the first groove 206 (as shown in Fig. 2 ) may comprise a plurality of vertical sections 316-1, 316-2, 316-3, 316-4 (as shown in Fig. 3) to accommodate corresponding vertical sections of the heating element 112. The distribution of the vertical sections of the heating element 112 across the first anode surface 204 may facilitate uniform heating of the anode flow field plate 102.
[0041] In an example, in the assembled state of the plate assembly
100, the first anode surface 204 (as shown in Fig. 2) and the first cathode surface 302 may contact each other. Accordingly, the first groove 206 (as shown in Fig. 2) and the second groove 304 may face each other. Further, the heating element 112 may be positioned in the first groove 206 (as shown in Fig. 2) as well as in the second groove 304. For instance, the vertical sections 306-1-306-4 of the heating element 112 may be spread across the first cathode surface 302 and the first anode surface 204 to heat the cathode flow field plate 104 and the anode flow field plate 102 uniformly. In this regard, as the heating element 112 is supplied with electric current, the heating element 112 may heat the anode flow field plate 104 as well as the cathode flow field plate 104.
[0042] Fig. 4 illustrates a sectional view of the plate assembly 100, in
accordance with an implementation of the present subject matter.
[0043] Here, the plurality of vertical sections, such as 402-1, 402-2,
402-3 of the first groove 206, which are distributed across the first anode surface 204 is shown. The vertical sections 306-1, 306-2, 306-3, 306-4 (as

shown in Fig. 3) of the heating element 112 positioned in the corresponding vertical sections 402-1, 402-2, 402-3 of the first groove 206 and in the corresponding vertical sections 316-1, 316-2, 316-3, 316-4 (as shown in Fig. 3) of the second groove 304 may be uniformly distributed across the first anode surface 204 and the first cathode surface 302.
[0044] In the assembled state of the plate assembly 100, where the
first cathode surface 302 contacts the first anode surface 204, the first groove 206 may be symmetrical to the second groove 304. For instance, as the first anode surface 204 and the first cathode surface 302 contact each other, the first groove 206 may be a mirror image of the second groove 304 with respect to a plane of contact between the first cathode surface 302 and the first anode surface 204. That is, a length of the first groove 206, a width of the first groove 206, and the depth of the first groove 206 may be equal to a length of the second groove 304, a width of the second groove 304, and the depth of the second groove 304. Further, a distance between the vertical sections 402-1, 402-2, 402-3 of the first groove 206 may be the same as a distance between vertical sections 316-1 -316-2, 316-3, 316-4 (as shown in Fig. 3) of the second groove 304. For instance, a distance between the first vertical section 316-1 of the first groove 206 and the vertical section 316-3 of the first groove 206 may be same as a distance between the vertical section 402-1 and the vertical section 402-3 of the second groove 306.
[0045] Further, in an example, as the first cathode surface 302 and
the first anode surface 204 contact each other, the first groove 206 and the second groove 304 may face each other, such that the heating element 112 may be accommodated in the first groove 206 as well as in the second groove 304. For instance, the first groove 206 and the second groove 304 may face each other, such that one-half of a thickness of the heating element 112 may be accommodated in the first groove 206 and a remaining half of a thickness of the heating element 112 may be accommodated in the second groove 304. In an example, the heating element 112 may be of circular cross-section and

the first groove 206 and the second groove 304 may form a rectangular cross-section together on engaging with each other. Furthermore, in an example, a thickness of the heating element 112 may be lesser than a sum of a depth of the first groove 206, and a depth of the second groove 304.
[0046] Fig. 5 illustrates a block diagram of a fuel cell stack 500, in
accordance with an implementation of the present subject matter.
[0047] The fuel cell stack 500 may be, for example, a high-
temperature polymer electrolyte membrane fuel cell stack (HT-PEMFC). Such a fuel cell stack 500 may comprise a plurality of fuel cells, each of which may have to be heated to a temperature of 80° C to 150° C to produce electric current. Further, such fuel cells may comprise a polymer electrolyte membrane between an anode and a cathode to allow flow of hydrogen ions from the anode to the cathode, as will be described below.
[0048] The fuel cell stack 500 may comprise a plurality of fuel cells,
such as a first fuel cell 502 and a second fuel cell 504. The first fuel cell 502 may comprise a first anode flow field plate 506, a first anode 508, a first cathode 510, and a first cathode flow field plate 104. The second fuel cell 504 may comprise a second anode flow field plate 102, a second anode 516, a second cathode 518, and a second cathode flow field plate 520. To distinguish the anode flow field plate 102 from the anode flow field plate 506, the anode flow field plate 102 may be referred to as the second anode flow field plate 102. Similarly, to distinguish the cathode flow field plate 104 from the cathode flow field plate 520, the cathode flow field plate 104 may be referred to as the first cathode flow field plate 104.
[0049] The first fuel cell 502 may further comprise a first membrane
electrode assembly (MEA) 526. The first MEA 526 may comprise a first polymer electrolyte membrane (PEM) 528. In an example, the first anode 508 and the first cathode 510 may be part of the first MEA 526. The first MEA 526 may be positioned between the first anode flow field plate 506 and the first cathode flow field plate 104. The first anode flow field plate 506 may supply

fuel to the first anode 508. Accordingly, the first anode 508 may be positioned adjacent to the first anode flow field plate 506 to perform oxidation of fuel. The fuel may be, for example, hydrogen fuel. The first cathode flow field plate 104 may be positioned adjacent to the first cathode 510 to supply oxidant to i the first cathode 510. The oxidant may be, for example, air.
[0050] The first PEM 528 may be positioned between the first anode
508 and the first cathode 510. The first fuel cell 502 may comprise a first gas distribution layer (not shown in Fig. 5) and a second gas distribution layer (not shown in Fig. 5). The first gas distribution layer may be positioned between
i the first anode flow field plate 506 and the first anode 508. The first gas distribution layer may allow access of fuel from the first anode flow field plate 506 to the first anode 508. The second gas distribution layer may be positioned between the first cathode flow field plate 104 and the first cathode 510. The second gas distribution layer may allow access of the oxidant from
i the first cathode flow field plate 104 to the first cathode 510.
[0051] In operation, at the first anode 508, hydrogen fuel may be split
into hydrogen ions and electrons. The first PEM 528 may conduct the hydrogen ions to reach the first cathode 510. On the other hand, the first PEM 528 may prevent the electrons to pass through it. The electrons may pass i through an external circuit to reach the first cathode 510. This flow of electrons causes electrical current. Further, at the first cathode 510, the oxygen, the hydrogen ions, and the electrons, react to form water.
[0052] Further, the second fuel cell 504 may comprise a second MEA
529. The second MEA 529 may comprise a second PEM 530. The second i anode 516 and the second cathode 518 may be part of the second MEA 529. The second MEA 529 may be positioned between the second anode flow field plate 102 and the second cathode flow field plate 520.
[0053] As mentioned earlier, the second anode flow field plate 102
may face and may be in contact with the first cathode flow field plate 104. For

instance, the first anode surface 204 (as shown in Fig. 2) may face and may be in contact with the first cathode surface 302 (as shown in Fig. 3).
[0054] The second anode flow field plate 102 may supply fuel to the
second anode 516 of the second fuel cell 504. Accordingly, the second anode 516 may be positioned adjacent to the second anode flow field plate 102 and the second cathode flow field plate 520 may be positioned adjacent to the second cathode 518.The second PEM 530 may be positioned between the second anode 516 and the second cathode 518.
[0055] Similar to the first fuel cell 502, the second fuel cell 504 may
comprise a third gas distribution later (not shown in Fig. 5) and a fourth gas distribution layer (not shown in Fig. 5). Further, the working of second fuel cell 504 may be similar to the working of the first fuel cell 502.
[0056] An MEA of each fuel cell of the fuel cell stack 500 may have
to be heated to an operating temperature 80° C to 150° C. Accordingly, the fuel cell stack 500 may comprise the heating element 112 positioned in the first cathode flow field plate 104 and on the second anode flow field plate 102. The heating element 112, the first cathode flow field plate 104, and the second anode flow field plate 102 may be part of the plate assembly 100, as explained with reference to Figs. 1-4. The heating element 112 may be positioned, for example, in at least one of a groove of a surface of the second anode flow field plate 102 and a groove of a surface of the first cathode flow field plate 104. For instance, the heating element 112 may be positioned at least in one of the first groove 206 and the second groove 304. In an example, the heating element 112 may be positioned in the first groove 206 as well the second groove 304, as explained earlier.
[0057] The heating element 112 may comprise the plurality of
sections, such as the plurality of vertical sections 306-1, 306-2, 306-3, 306-4 (as shown in Fig. 3) distributed over, for example, at least one of a surface of the second anode flow field plate 102 and a surface of the first cathode flow field plate 104. In an example, the plurality of vertical sections 306-1, 306-2,

306-3, 306-4 may be distributed over the first cathode surface 302 as well as the first anode surface 204, to facilitate uniform heating over the cathode flow field plate 104 and the anode flow field plate 102, as explained earlier.
[0058] During operation, when the heating element 112 is supplied
i with the electrical current, the heating element 112 may heat the first cathode
flow field plate 104 and the second anode flow field plate 102. By the virtue
of the design of the plate assembly 100, the heating element 112 may
uniformly heat the first cathode flow field plate 104 and the second anode
flow field plate 102 upon supplying electric current. That is, a uniform
i temperature distribution across the first cathode flow field plate 104 and the
second anode flow field plate 102 may be achieved by heating using the
heating element 112. As a result, the first MEA 526 and the second MEA 529
also get heated uniformly to achieve a uniform temperature distribution
across first MEA 526 and the second MEA 529. The heating temperature may
i be, for example, temperature between 80° C and 150° C.
[0059] The performance of the fuel cell may depend on heat
distribution across a MEA of a fuel cell. A non-uniform heat distribution across the MEA may give rise to poor utilization of reactants in the fuel cell, resulting in poor performance of the fuel cell. For instance, in techniques, where a
i heating element is positioned between or around the flow channels of the anode flow field plate, and between or around the cathode flow field plate, the performance of the fuel cells may be poor due to non-uniform temperature distribution caused by such heating element. The present subject matter, by achieving uniform distribution of heat across the MEA, may facilitate effective
i utilization of reactants and may enhance the performance of the fuel cell.
[0060] Although in the above description is explained with respect to
examples in which the fuel cell stack has separate anode flow field plates and cathode flow field plates, the fuel cell stack 500 may comprise a plurality of bipolar plates (not shown in Fig. 5). Each bipolar plate may have a cathode i flow channels on one side of the bipolar plate and an anode flow channels on

behind/rear side of the cathode flow channels. Accordingly, the bipolar plates may be shared between adjacent fuel cells such that the cathode flow channels of the bipolar plate may be a part of one fuel cell to supply oxidant to that fuel cell and the anode flow channels of the bipolar plate may be a i part of an adjacent fuel cell to supply fuel to that fuel cell.
[0061] The present subject matter enables efficient and quick heating
of the fuel cells. For instance, since the plate assembly comprises the heating element, the present subject matter facilitates heating of the fuel cells to elevated temperatures in a reduced time span. This, in turn, decreases the i starting time of the fuel cells. Further, the present subject matter may achieve a uniform temperature distribution across the fuel cell. As a result, the present subject matter may enhance the performance of the fuel cells.
[0062] Although the present subject matter has been described with
reference to specific implementations, this description is not meant to be i construed in a limiting sense. Various modifications of the disclosed implementations, as well as alternate implementations of the subject matter, will become apparent to persons skilled in the art upon reference to the description of the subject matter.

I/We Claim:
1. A plate assembly (100) for a fuel cell stack comprising:
a cathode flow field plate (104) to supply oxidant to a cathode
of a first fuel cell of the fuel cell stack, the cathode flow field plate
5 (104) having a first cathode surface (302) and a second cathode
surface (202);
an anode flow field plate (102) to supply fuel to an anode of
a second fuel cell of the fuel cell stack, the anode flow field plate
(102) having a first anode surface (204) and a second anode surface
10 (106), wherein the first cathode surface (302) faces and is in contact
with the first anode surface (204); and
a heating element (112) positioned in a first groove (206) of a first grooved surface, the first grooved surface being one of: the first cathode surface (302) and the first anode surface (204).
15 2. The plate assembly (100) as claimed in claim 1, wherein the heating
element (112) is a heating coil.
3. The plate assembly (100) as claimed in claim 1, wherein the heating
element (112) is positioned in a second groove (304) of a second grooved
surface, the second grooved surface being the other of: the first cathode
20 surface (302) and the first anode surface (204), wherein the first groove (206) is symmetrical to the second groove (304).
4. The plate assembly (100) as claimed in claim 3, wherein the first
anode surface (204) comprises the first groove (206) and the second anode
surface (106) comprises a first plurality of flow channels (108) to facilitate fuel
25 flow and wherein the first cathode surface (302) comprises the second groove (304) and the second cathode surface (202) comprises a second plurality of flow channels (110) to facilitate oxidant flow.

5. The plate assembly (100) as claimed in claim 3, wherein a shape of the second groove (304) on the second grooved surface corresponds to a shape of the heating element (112).
6. The plate assembly (100) as claimed in claim 1, wherein a shape of the first groove (206) on the first grooved surface corresponds to a shape of the heating element (112).
7 The plate assembly (100) as claimed in claim 1, wherein a portion of the heating element (112) extends out of the first groove (206) to be connected to a power supply.
8. The plate assembly (100) as claimed in claim 1, wherein the cathode flow field plate (104) and the anode flow field plate (102) are made of graphite.
9. A fuel cell stack (500) comprising:
a first fuel cell (502) comprising: a first anode flow field plate (506); a first anode (508); a first PEM (528); a first cathode (510); and a first cathode flow field plate (104); and a second fuel cell (504) comprising:
a second anode flow field plate (102) in contact with the first cathode flow field plate (104); a second anode (516); a second PEM (530); a second cathode (518); and a second cathode flow field plate (520); and a heating element (112) positioned between the first cathode flow field plate (104) and the second anode flow field plate (102).

10. The fuel cell stack (500) as claimed in claim 9, wherein the heating element (112) is positioned in at least one of a groove of a surface of the second anode flow field plate (102) and in a groove of a surface of the first cathode flow field plate (104).
11. The fuel cell stack (500) as claimed in claim 9, wherein the heating element (112) comprises a plurality of sections distributed over at least one of a surface of the first cathode flow field plate (104) and a surface of the second anode flow field plate (102).
12. The fuel cell stack (500) as claimed in claim 11, wherein the heating element (112) is a serpentine-shaped heating coil.