MX2008010014A - Variable compressibility gaskets - Google Patents

Abstract

A gasket formed of compressible material and having a first sealing surface and a second sealing surface for providing a fluid seal between a first component and a second component, a plurality of cavities provided within the gasket proximate the first and/or second sealing surfaces and extending over at least a first portion of the gasket to provide increased compressibility of the gasket in the first portion.

Description

VARIABLE COMPRESSIBILITY PACKAGES DESCRIPTIVE MEMORY The present invention relates to packaging, and in particular, packaging for use in fuel cell assemblies. Conventional electrochemical fuel cells convert fuel and oxidant into electrical energy and a reaction product. A typical presentation of a conventional fuel cell 10 is shown in Figure 1 which, for reasons of clarity, illustrates the various layers in schematic form. A solid polymeric ion transfer membrane 11 is inserted between an anode 12 and a cathode 13. Usually, the anode 12 and the cathode 13 are both formed of a porous electrically conductive material such as porous carbon, to which small particles are attached. of platinum and / or other precious metal catalysts. The anode 12 and cathode 13 often attach directly to the respective adjacent surfaces of the membrane 11. This combination is commonly referred to as the membrane-electrode assembly, or MEA. The insertion of the polymer membrane and porous electrode layers is an anode fluid flow field plate 14 and a cathode fluid flow field plate 15. The intermediate reinforcement layers 12a and 13a can also be used between the anode fluid flow field plate 14 and the anode 12 and similarly between the cathode fluid flow field 15 plate and the cathode 13. The reinforcement layers are of a porous nature and are fabricated to ensure a Effective gas diffusion to and from the anode and cathode surfaces as well as to assist in the management of water vapor and liquid water. The fluid flow field plates 14, 15 are formed of a non-porous electrically conductive material through which electrical contact can be made with the respective anode electrode 12 or cathode electrode 13. At the same time, the field plates fluid flow facilitates the delivery and / or escape of fluid fuel, oxidant and / or reaction product to and from the porous electrodes 12, 13. This is conventionally done by forming fluid flow passages on a surface of the plates of fluid flow field, such as slots or channels 51 in the surface presented to the porous electrodes 12, 13. Referring also to Figure 2a, a conventional fluid flow channel configuration provides a serpentine structure 20 on one side of the anode 14 (or cathode 15) having an input manifold 21 and an output manifold 22 as shown in FIG. 2a. According to the conventional design, it will be understood that the serpentine structure 20 comprises a channel 16 on the surface of the plate 14 (or 15), while the manifolds 21 and 22 each comprise an opening through the plate in a manner that the supply fluid to or from the channel 20 can be communicated through the full depth of a stack of plates in a direction orthogonal to the plate as particularly indicated by the arrow in the cross section in AA shown in figure 2b. With reference to Figure 3, in stacks of conventional fuel cells 30, stacks of plates are incorporated. In this arrangement, adjacent plates of anode and cathode fluid flow fields are combined in a conventional manner to form a single bipolar plate 31 having anode channels 32 on one side and cathode channels 33 on the opposite side, each adjacent to a respective membrane-electrode assembly (MEA) 34. The openings of the inlet manifold 21 and openings of the outlet manifold 22 are all coated to provide input and output manifolds to the entire stack. The various elements of the stack are shown slightly separated for purposes of clarity, although it will be understood for purposes of the present invention, that they will be compressed together using sealing gaskets. With reference to figure 4, an anode face of an electrode-membrane assembly 40 is coated with a seal packing 41 around its perimeter. The seal package 41 includes two openings 42, 43, around a fluid inlet port 44 and a fluid outlet port 45 at a periphery of the anode face of the MEA 40. An electrically conductive anode plate 46 (shown in dotted pattern in figure 4b and slightly separated for reasons of clarity, but omitted in figure 4a to reveal the structures below) covers the sealing package 41.

The anode face of the MEA 40, the seal package 41 and the anode plate 46 together define a fluid containment volume 47 between the fluid inlet port 44 and the fluid outlet port 45. The containment volume of fluid is realized through the impermeability of the anode plate 46 and sealing gasket 41 together with the limited permeability of the MEA (i.e., leaving substantially only ionic flow). Within this containment volume 47 a sheet of diffuser material 48 extends. The sheet of diffuser material is cut into a shape which results in the formation of one or more chambers 49, 50 defined between a side edge 51, 52 of the blade 48 and the sealing gasket 41. In particular, as shown in FIG. 4, the first chamber 49 constitutes an inlet chamber that extends around a main portion of the peripheral side edge 51 of the sheet 48 of the diffuser material (that is, most of the three sides). The second chamber 50 constitutes an outlet chamber that extends around a smaller portion of the peripheral side edge 52 of the sheet 48 of diffuser material. Conventional packaging, being of uniform thickness and composition, will normally suffice when the sealing surfaces are uniformly flat and parallel. A uniform compression applied on the sealing surfaces can then provide an adequate seal. However, in certain circumstances the use of such conventional packaging may not be optimal. For example, when surface features such as additional components are to be included in a sealing surface, the uniform compressibility of a package will result in uneven pressure across the packing area. The regions of reduced distance between sealing surfaces, for example due to surface protuberances, will be subjected to higher pressures, and the regions of increased distance between sealing surfaces, for example surrounding said protuberances, will be subjected to consequently lower pressures. . This can reduce the reliability and / or effectiveness of a seal. In addition, a conventional package may have the tendency to expand at the edges of the sealing area under pressure, displacing the packing material out of the sealing area. For a conventional packaging material, therefore, high pressures may be necessary to ensure that an adequate seal is obtained. For thin packings in particular, the pressure required may be even higher, because the compressibility of the packing is reduced. Alternatively, the requirements for the surfaces to have a flat character and a parallelism with a wider tolerance can be increased. Under high pressures, a package can also be subjected to material runoff which, over time, could reduce the effectiveness of the seal. This reduction in effectiveness can also be exacerbated by the thermal cycle. One solution to the aforementioned problems is to create specially designed three-dimensional gaskets specifically configured to fit profiled surfaces. However, these packages can be prohibitively expensive and being of variable thickness, they may not even provide a sufficiently uniform seal in certain circumstances such as in the example of fuel cells shown herein. Another solution is to increase the compressibility of the packaging material, in order to adapt to non-uniform surfaces and allow a reduced sealing pressure. However, such packages may have an undesirable increased tendency to move out of the sealing area. Therefore, there is a need for a package that can be effectively sealed against non-uniform surfaces that have a reduced tendency to move out of the sealing area, be capable of sealing under lower sealing pressures and have a low manufacturing cost. compared to special design three-dimensional packaging. It is an object of the present invention to provide a package that overcomes one or more of the problems of the prior art packages. According to a first aspect, the present invention provides a package formed of compressible material and having a first sealing surface and a second sealing surface for providing a fluid seal between a first component and a second component, a plurality of cavities provided proximate to the first and / or second sealing surfaces and extending over at least one first portion of the package to provide increased package compressibility in the first portion. According to a second aspect, the present invention provides a method for sealing a fuel cell comprising: providing a package formed of compressible material having a first sealing surface and a second sealing surface and a plurality of cavities close to the first and / or second sealing surfaces and extending over at least a second portion of the package to provide increased package compressibility in the first portion; placing the packing between a fluid flow field plate and a membrane-electrode assembly and applying compressive pressure between the fluid flow field plate and the membrane-electrode assembly through the packing to provide a fluid seal between the same. According to a third aspect, the present invention provides a fuel cell comprising: an electrode membrane assembly; a fluid flow field plate; and a package according to the first aspect. The advantages of the invention, as compared to conventional packages, can include a reduction in a total applied load necessary to form a seal, an improved ability of the package to maintain a seal after thermal cycling, and a capacity to seal around protrusions of surface on one or both of the sealing surfaces.

The embodiments of the present invention will now be described by way of example and with reference to the accompanying drawings, in which: Figure 1 shows a schematic cross-sectional view through a part of a conventional fuel cell; Figures 2a and 2b show respectively a simplified and cross-sectional view of a fluid flow field plate of the fuel cell of Figure 1; Figure 3 shows a cross-sectional view through a stack of conventional fuel cells with bipolar plates; Fig. 4a shows a plan view of an anode configuration having a diffuser material sheet positioned with respect to a sealing gasket and fluid inlet and outlet ports, and Fig. 4b shows the corresponding transverse side view in the line AA; Figure 5 shows a perspective view of the construction of part of a package of the present invention; Figure 6 shows a cross-sectional view of a portion of a package of one embodiment of the present invention; Figure 7 shows a schematic cross-sectional view of a portion of a package according to an embodiment of the present invention being under an applied pressure; Figure 8 shows a plan view of a closed cell grid structure of cavities of a package according to a preferred embodiment of the invention; Figure 9 shows a plan view of a closed cell grid structure of cavities of a package according to a preferred embodiment of the invention, with additional fluid distribution channel cavities; Figure 10 shows a plan view of an alternative closed cell grid structure of cavities of a package according to a preferred embodiment of the invention; Figure 11 shows a plan view of an anode configuration having two portions of packaging material of different special design; Fig. 12 shows a perspective view of an alternative packing configuration comprising regions of open cell and closed cell; Figure 13 shows a plan view of another alternative packing configuration comprising regions of open cell and closed cell; Fig. 14 shows a plan view of another alternative packing configuration comprising a fluid port together with open and closed cell regions; and Figure 15 shows a plan view of an alternative configuration of a package comprising a fluid port, fluid supply channels and fluid connection with an external fluid manifold. Conventional designs of anode and cathode fluid flow plates incorporating fluid flow channels in their faces have already been discussed with respect to Figures 1 to 3, and the arrangement of a typical package for use with such plates has been treated with respect to Figure 4. Figure 5 illustrates a representative portion of a package 53 of the present invention. The package 53 has a first sealing surface 54 and a second sealing surface 55. A first plurality of cavities 56 is provided within the package 53 in the first sealing surface and extends over the package portion. In this particular embodiment, the cavities 56 extend in a regular array over the portion of the package 53 shown. A second plurality of cavities 57 provided within the package on the second sealing surface 55 is also shown, being in this embodiment substantially similar in size and arrangement to the first plurality of cavities. Although the cavities 56 are shown in Figure 5 provided on the surface 54, in other embodiments the cavities 56 may be provided below the surface 54, but sufficiently close to the surface to influence the local surface compressibility through the thickness of the packaging 53.

The sealing surface 54, 55 of the package is defined as that surface that is in contact with the surface of the component to which the package will be sealed. Therefore, the sealing surface generally does not include the interior surface of the cavities 56, 57. However, as the pressure applied to the packing 53 increases, a proportion of the interior surface of the cavities 56, 57 may become part of the sealing surface of the package 53, which proportion increases with increasing applied pressure. The term "cavity density" is used herein as a measure of the number of cavities present over any defined area of the packing 53. The cavity density on a first sealing surface 54 of a portion of the packing 53 may be different from the cavity density on a second sealing surface 55 of the same portion of the packaging 53. For example, if the area of the sealing surface 54 of the packaging 53 of Figure 5 is 1 cm2 and the number of cavities is 36, the Cavity density in the first sealing surface is 36 cm "2. The term" cavity volume "as used herein is the total void volume of any given cavity, which can be useful in terms of a figure average for cavities in the package 53 or in a certain region thereof It will be recognized that the cavity density and cavity volume in a region of the package will each determine at least in part the compressibility from that region of the package.

The term "compressible material" is intended to encompass solid materials which can be significantly deformed under applied compressive pressure, and whose physical mechanical properties may be characterized by a combination of elastic deformation, ie, recoverable, and plastic, that is, permanent and non-recoverable. , under an applied pressure. Time-dependent effects such as runoff and viscoelasticity can also partly define the properties of the compressible material. An increase in the compressibility of a region of the package will correspond to a reduction in the pressure needed to compress the total thickness of that region to the same degree. Put alternatively, the same applied pressure will cause the total thickness of that region to be reduced to a greater degree. In Figure 6 a cross-sectional view of an alternative asymmetric arrangement of cavities 62, 63 is shown in a package 61 of the present invention, wherein the cavity volumes are different in the first sealing surface 64 and the second sealing surface 65 The cavities 62 near the first sealing surface 64 have different dimensions than the cavities 63 near the second sealing surface 65. The result of this type of variation in cavity volume will be that the packing material 66 between the cavities more 63 is able to compress even more than the packing material 67 between the smaller cavities 62 under the same applied pressure.

An effect similar to that shown in Figure 6 can be obtained, instead of altering the average cavity volume below each of the first 64 and second 65 sealing surfaces, by altering the separation between the cavities and thus affecting the cavity density. The cavity density and / or cavity volumes may be different in at least opposite surface portions selected from the packaging close to the first 64 and second 65 sealing surfaces, the opposing surface portions being selected regions of the first 64 and second 65 sealing surfaces that are substantially coextensive on opposite sealing surfaces of the package 61. In said asymmetric arrangement in the package 61 of Figure 6, the surface adhesion properties can be consequently diverted to a surface. The contact area of a sealing surface 64 of the package 61 compared to the other sealing surface 65 will tend to prefer adhesion to one surface over the other without the need for adhesives or surface preparations. In figure 7 a schematic cross-sectional view of the behavior of said packing 61 under compression between an upper component 77 and a lower component 76 is shown. The packing 61 is located between two component surfaces 74, 75. On the component surface lower 74 is a surface feature 73, which protrudes from the plane of the component surface 74. The application of pressure in the direction indicated by the arrow 71 causes the packing material in the compensation region 72 to compress more than the material outside the compensation region. The additional compression of the package is captured within the volume of the package itself, and does not cause any further widening around the outer perimeter of the package 61. The cavities 63 allow the surrounding packing material within the compensation region 72 to widen in the cavities 63 along directions orthogonal to the force application direction. The surface feature 73, for example, may be a sheet or wedge of relatively incompressible material, such as a water distribution sheet, positioned to cover selected regions of the fluid flow plate. Because the gasket 61 is capable of compressibly deforming about the surface feature 73, the seal around the surface feature is not compromised by its presence. The gasket 51, 61 of the present invention may preferably comprise rectangular cavities 56, 57, 62, 63 arranged in a regular array, for example in a square design substantially uniformly spaced, as shown in Figure 5. They are also contemplated other types of regular repetition patterns such as hexagonal or triangular patterns. Also contemplated within the scope of the invention are non-repetitive patterns or random distributions of cavities, which may also be characterized by a cavity density and an average cavity volume.

It will be understood that the term "cavities" is intended to encompass definitions that apply to individually isolated cavity arrangements through a package, as well as interconnected cavity arrangements formed within individually isolated pillars arrangements or other elevated features. A package of the present invention may comprise one or both types of cavities through at least a portion of one or both sealing surfaces. It is contemplated that a variety of conventional packaging materials may be used in the present invention, such as butyl, nitrile or silicone gums. However, other materials such as expanded PTFE can also be used. The thickness of the packing preferably is less than 10 mm. Preferably, the thickness of the non-compressed package is between 0.1 and 3 mm, and preferably between 0.1 and 1 mm. Preferably, the average volume of the cavities 56, 57, 62, 63 is less than 5 mm3, and in particular it is within the range of 0.001 to 1mm3. The cavities preferably have a substantially cube shape, although the cavities can have any suitable shape, and also preferably have an average linear dimension within the range of 0.1 to 1mm. The cavities of a package 53, 61 of the present invention are preferably formed by applying a texture to the surface or surfaces of a package of uniform thickness. This texturing can be performed by compression molding of the package, for example between platens configured under conditions of heat and pressure in order to plastically deform the packaging material in the required form. Alternatively, various known techniques can be used to form the packaging material of the present invention, such as casting, injection molding or rolling / calendering using textured rolls. A possible additional function that the cavities of the present invention can perform is that of fluid distribution. Figure 8 shows a closed cell grid structure of cavities in a package according to the present invention, with a sealing surface 54 and isolated cavities 56. By altering this design so that the selected cavities are extended and made interconnect more than isolate one from another, an arrangement such as that shown in figure 9 can be reached. The package 90 has formed within itself as part of the cavity pattern, a series of interconnected fluid supply channels 91 , 92, 94. Each of these fluid feed channels, as for the surrounding cavities 56, has a depth which extends at least partially through the thickness of the packing 90. In the case where the packing is formed directly In the fluid flow field plate, for example by molding, the fluid feed channels can extend through the entire thickness of the package. A fluid inlet channel 91 is connected to a plurality of fluid outlet channels 92 through fluid distribution channels 94. The preferred direction of fluid flow in use is indicated by arrows 93. Together with openings 42 , 43 provided in the package 41, as shown in Figure 4, the arrangement illustrated in Figure 9 may have a special design for distributing fluid from the fluid inlet port 44 through various ports of the chamber 49 adjacent to the membrane-electrode assembly 40. The same type of arrangement can also apply to a fluid outlet port 45. The compressibility of the package 90, which can have a special design through the density, depth and size of the cavities 56 , can be used to control to a certain extent the degree to which the fluid feed channels 91, 92, 94 are capable of passing fluid. With an applied pressure increased through the packing 90, the fluid feed channels 91, 92, 94 will become more restricted, tending to bring the fluid paths 93 closer together. This will increase the back pressure at the fluid inlet port 44. This can help improve the accuracy of the fluid distribution through a number of membrane-electrode assemblies. The precision and speed of fluid measurement can then be at least partially controlled by the pressure applied through the fuel cell assembly 30 comprising a package 91 of the type of Figure 9. Separate components which would otherwise be necessary for performing these functions can then be advantageously withdrawn.

An alternative packing arrangement is illustrated in Figure 10, in which a package 101 is provided with cavities 103 arranged in a regular grid pattern below the sealing surface 102. In this arrangement, the volume and / or density of the cavity they can be increased beyond the possible in the arrangement shown in Figure 8 while maintaining the fluid insulation of each cavity during use. Other types of cavity arrangements, not restricted to square cavities or arrangements of regular grids of the type illustrated as an example, can also be contemplated. For example, circular cavities can be beneficial in terms of ease of fabrication. Other forms are also possible. The cavities 56, 57, 62, 63 within a package 53, 61 may be provided within certain predetermined portions of the package 53, 61, according to their position in the package and the function they are required to perform. In Figure 11 there is shown an exemplary arrangement of an anode configuration with a gasket 41 surrounding a first chamber 49 and a second chamber 50 in an arrangement similar to that shown in Figure 4. A first portion 41a of the gasket has a special design, in accordance with the principles illustrated in Figure 9 and detailed above, to have fluid distribution channels 94 within the first portion 41a and with fluid outlet channels 92 provided in the interior perimeter portion 110 of the packaging 41 in fluid communication with the first chamber 49. The fluid inlet channel 91 of the first portion 41a coincides with the fluid inlet port 44 in the opening 42 in the package 41. The fluid entering the inlet channel of the fluid 91 is distributed along the inner perimeter 1 0 of the package close to the first chamber 49, through the fluid distribution channels 94 provided within the first portion 41a of the package 41. The second portion 41b of the package 41 has a special design in this example in the manner illustrated in figures 5 and 8, and above detailed, so that the fluid leaves the second chamber 50 through from the fluid outlet port 45 located in an opening 43 in the package 41. The distribution of fluid through the package can be achieved through the special design of open cell regions of the package. An example of such gasket 120 is shown in Fig. 12, which comprises closed cell regions 122 and open cell regions 121. Fluid can flow into the open cell regions around pillars 123, which in this example are formed as circular or oval cylinders. The pillars 123 may alternatively be cylinders of rectangular or polygonal section, or even of variable section such as conical or pyramidal shapes. The arrangement of the pillars can be of any suitable repetition or non-repetition pattern, or they can be randomly distributed. Examples of possible patterns include regular square patterns or hexagonal or diagonal packing. The pillars 123 may be advantageously formed to have a selected height that is different from that of the surrounding closed cell region. The selection of the pillars to have a reduced height allows the distortion to be reduced when the package 120 is under compressive pressure. The reduced height of said pillars can also serve to support components which could coat the open cell region. The selection of the pillars 123 to be higher than the surrounding packing will result in the pillars compressing more than the surrounding material, which can be used to measure fluid flow through the open cell region 121. As shown in Figure 13, the open cell region 121 may itself comprise a fluid inlet and / or outlet port, in this example it consists of a series of fluid channels 131 that extend through the packing and are limited by Closed cell regions 122. As shown in Figure 14, the package may comprise a fluid port 141, which may be for fluid inlet or outlet. The fluid port 141 is surrounded by a closed cell region 143, except for when the passage of fluid through the package is required, where there is a fluid supply region 142 comprising an open cell region as in the figure 12. This open cell region 142 may comprise a series of fluid channels or alternatively may comprise a plurality of interconnected cavities formed between raised pillars of the packaging material. It will be understood that the package of the present invention need not be of a unitary construction, ie, be formed entirely of a type of compressible material, but instead may be formed of more than one type of material. For example, the package may consist of a first layer of compressible material in which the cavities are provided and a second underlying layer of a relatively incompressible material. The first layer can be applied through any sble means, for example by screen printing, lamination, molding or other methods. A pattern in the layer of compressible material can thus define an arrangement of cavities through at least a portion of one or both of the sealing surfaces of the package. For example, a silicone rubber pattern may be applied by screen printing to one or both surfaces of a polyester sheet, thereby forming an elastically compressible surface layer after curing. The surface layer thus formed imparts improved sealing properties to the sheet, which might otherwise be unsble for sealing applications. Preferably, patterns such as those illustrated in Figures 8-10 may be applied although any sble pattern comprising cavities is contemplated. In Figure 15 a further alternative arrangement of a package 150 is shown, in which a combination of closed cell and open cell regions is provided to form defined fluid delivery regions within the package 150. A fluid port 153 is surrounded for a closed cell region 154, except for a region comprising fluid supply channels 152a. The fluid supply channels 152 fluidly connect the fluid port 153 with an interior volume 155 defined by the package 150. An additional region of fluid supply channels 152b serves to connect the interior volume 155 defined by the package 150 to an external manifold 151. For example, the external manifold 151 can be used to supply refrigerant to the fuel cell, while the fluid port 153 supplies oxidant. The gaskets as described herein meet the particularly exact requirements for gaskets used in fuel cells. Typically, such fuel cell gaskets are required to have high dimensional accuracy over a large area and may need to obtain a seal over a large surface area with a compression of, for example, only 0.2 mm for each cell. To reduce the distortion of a fuel cell stack having many individual cells, and to allow an adequate volume for a diffusing layer within each cell, the thickness dimensions of a sealing gasket may need to vary only about 10% when a sealing pressure is applied. Therefore, surfaces with a high tolerance on matching surfaces of the packages are required to prevent leakage. However, fuel cell gaskets also require sufficient elasticity and flexibility to allow thermal expansion and contraction of other components such as tie rods that pass through the cells of a cell. A high degree of pressure is required in the loading and sealing of fuel cell stacks and gaskets described here offer surprisingly important advantages in this regard. The cavities of the described packages allow a reduction in load and an improved capacity to seal around surface protrusions and allow certain dimensional and load tolerances to be relaxed without compromising the sealing capacity of the packaging or the dimensional accuracy throughout. the thickness of a stack of fuel cells. It is contemplated that other embodiments are within the scope of the appended claims.

Claims (14)

NOVELTY OF THE INVENTION CLAIMS

1. - A package formed of compressible material and having a first sealing surface and a second sealing surface for providing a fluid seal between a first component and a second component, a plurality of cavities provided in a manner close to the first and / or second sealing surfaces and extending over at least a first portion of the package to provide increased package compressibility in the first portion.

2. The package according to claim 1, further characterized in that the volume density and / or cavity volumes vary through at least one of the first and second sealing surfaces.

3. The package according to claim 1, further characterized in that the cavity density and / or cavity volumes are different in the first and second sealing surfaces.

4. The package according to claim 3, further characterized in that the cavity density and / or cavity volumes are different in opposite surface portions selected from the package.

5. - The package according to claim 1, further characterized in that the cavities are arranged in one or more regular arrangements.

6. The package according to any preceding claim, further characterized in that the cavities have an average linear dimension within the range of 0.1 to 1 mm.

7. - The package according to any preceding claim, further characterized in that the cavities have an average volume within the range of 0.001 to 1 mm3.

8. The package according to any preceding claim, further characterized in that the cavities are substantially cube-shaped.

9. The package according to any preceding claim, further characterized in that the cavities include a plurality of fluid feed channels provided within the package near the first sealing surface, each fluid supply channel having a depth extending at least partially through the packaging.

10. The package according to claim 9, further characterized in that the plurality of fluid feed channels are fluidly connected to an opening comprising a fluid inlet and / or outlet port.

11. The package according to claim 11, further characterized in that the plurality of fluid feed channels are adapted to be fluidly connected to a membrane-electrode assembly of a fuel cell.

12. The package according to any preceding claim, further characterized in that the package comprises a first layer of compressible material in which is provided the plurality of cavities and a second layer of relatively incompressible material near the first layer.

13. - A method for sealing a fuel cell, comprising: providing a package formed of compressible material having a first sealing surface and a second sealing surface and a plurality of cavities near the first and / or second surfaces of sealed and extending over at least a first portion of the package to provide increased package compressibility in the first portion; placing the packing between a fluid flow field plate and a membrane-electrode assembly; and applying compressive pressure between the fluid flow field plate and the membrane-electrode assembly through the packing to provide a fluid seal therebetween.

14. - A fuel cell comprising: an electrode membrane assembly; a fluid flow field plate; and a package of any of claims 1 to 12.