Stack arrangement for a fuel cell

Abstract

The invention relates to a stack (2), for a fuel cell, comprising a primary separator (10), with a primary circulation field (12) and a primary rim (13). The stack comprises a primary inner fin (20A), integral with the primary separator, projecting from the primary rim, connected to the primary circulation field and intended to bear against a primary gas-diffusion layer of a membrane electrode assembly (30). The stack comprises a primary peripheral seal (70), intended to be positioned between the primary rim and a peripheral zone of the membrane electrode assembly (30). According to the invention, the stack comprises a primary outer fin (71A), integral with the primary peripheral seal, which projects from the primary rim (13), which is offset with respect to the primary inner fin and which is intended to be positioned between the primary rim and the primary gas-diffusion layer.

Description

[0001] STACKING ARRANGEMENT FOR A FUEL CELL

[0002] The present invention relates to a stack for a fuel cell and a fuel cell comprising such a stack.

[0003] US2022271306A1 describes electrochemical cells, each comprising a superposition of a first separator, a membrane-electrode assembly and a second separator. The membrane-electrode assembly comprises an electrolytic membrane, coated by a cathode, on the side of the first separator, and by an anode, on the side of the second separator. The cathode and the anode each comprise a gas diffusion layer in contact with the first and second separators respectively. The membrane-electrode assembly also comprises a frame which surrounds the membrane. In order for the frame to be attached to the membrane, the inner periphery of the frame is arranged between the electrolytic membrane and the anode, the anode being locally lifted from the electrolytic membrane near its outer peripheral edge.

[0004] The separators are each made of a stamped sheet metal. The second separator of a first cell is joined to the first separator of the next cell to form a joined separator.

[0005] Each separator forms a respective circulation field, for a circulation of gas containing oxygen for the first separator, and for a circulation of gas containing dihydrogen for the second separator. For each separator, at the edge of the separator, the separator forms a peripheral sealing portion bearing against the sheet of the frame of the membrane-electrode assembly, with the interposition of an elastomer sealing gasket, to prevent gas leakage.

[0006] Each separator also forms anti-bypass protrusions, integral with the separator. In the transverse direction, each anti-bypass protrusion extends from the circulation field, towards the sealing portion, while being however distant from the sealing portion. Each anti-bypass protrusion bears against the gas diffusion layer, for their end superimposed with the membrane. Each protrusion is distant from the frame, for their end superimposed with the frame. A resin seal element is superimposed on the anti-bypass protrusion, for its part opposite the frame, in order to partially fill the space between the anti-bypass protrusion and the frame. The anti-bypass protrusions and these seal elements are intended to limit gas from bypassing the first circulation field, by passing between the first circulation field and the peripheral sealing portion.However, in practice, these known electrochemical cells may prove difficult to manufacture, particularly with regard to the elastomer seal carried by the peripheral sealing portion and the resin seal elements. Indeed, certain seal manufacturing processes that would be advantageous and inexpensive seem to be excluded because of the structure of these known electrochemical cells. In particular, overmolding of the seal and / or the resin seal elements onto the separator is difficult, if not impossible, to implement, because the anti-bypass protrusions integral with the separator as well as other reliefs and hollows formed by the separator, do not leave sufficient space for the application of an overmolding apparatus onto the separator.Therefore, although it may seem attractive to add an elastomeric element to attempt to fill the gap between the anti-bypass protrusion and the elastomeric seal, the practical implementation of this solution may prove costly and complex, in that it is not easy to form such an elastomeric element on a surface that has reliefs and depressions.

[0007] The aim of the invention is then to propose a new stack for a fuel cell, which, while being easier to manufacture, makes it possible to effectively limit a phenomenon of bypassing a circulation field by reactive fluid.

[0008] To this end, the invention relates to a stack, for a fuel cell, the stack defining a stacking direction, a transverse direction and a distinct longitudinal direction, and comprising:

[0009] - a primary separator, which extends perpendicular to the stacking direction and which comprises: a primary circulation field, for guiding a flow of primary reactive fluid, and a primary rim, which extends the primary separator beyond the primary circulation field in the transverse direction;

[0010] - a primary peripheral seal, which is interposed between the primary rim and a peripheral zone of a membrane electrode assembly along the stacking direction; and

[0011] - at least one primary internal fin, integral with the primary separator, which projects from the primary rim in the stacking direction, and which comprises: an internal base end, connected to the primary circulation field and intended to bear against a primary gas diffusion layer of the membrane electrode assembly, in the stacking direction, and an external free end, which is intended to be opposite the peripheral zone in the stacking direction.

[0012] According to the invention, the stack further comprises at least one primary external fin, which is integral with the primary peripheral seal, which projects, in relief in the stacking direction, from the primary rim, said at least one primary internal fin and said at least one primary external fin being offset from each other in the longitudinal direction, and said at least one primary external fin comprising:

[0013] - an external base end, connected to the primary peripheral seal; and

[0014] - an internal free end, intended to be interposed between the primary rim and the primary gas diffusion layer following the stacking direction.

[0015] An idea underlying the invention is to provide both at least one primary internal fin integral with the primary separator, in particular metallic, and a primary external fin integral with the primary peripheral seal, in particular made of elastomer. Said at least one primary internal fin is attached to the circulation field by the internal base end, but is advantageously distant from the primary peripheral seal, in the transverse direction, at the external free end. Said at least one primary internal fin therefore does not hinder the formation of the primary peripheral seal, in particular by overmolding. Similarly, said at least one primary external fin is attached to the primary peripheral seal by the external base end, but may advantageously be distant from the circulation field, so that the manufacture of said at least one primary external fin is not hindered, in particular by overmolding.It is advantageous to form both the primary peripheral seal and said at least one primary external fin, in a single operation, in particular overmolding. Despite the space provided between the external free end and the primary peripheral seal and the space provided between the internal free end and the primary circulation field, the bypassing of the primary circulation field by the primary reactive fluid is limited or prevented to the extent that said at least one primary external fin and said at least one primary internal fin are offset from each other in the longitudinal direction, and therefore follow one another in the longitudinal direction. This succession of fins in the longitudinal direction forms baffles along the primary circulation field, between the primary circulation field and the primary peripheral seal, which limits the bypassing of the primary circulation field by primary reactive fluid.

[0016] By "fin" we preferably mean a punctual and local outgrowth coming from material with and from the primary separator, in the case of the primary fin, or the seal, in the case of the external fin. Preferably, the fin has an elongated shape in the transverse direction Y, in particular in the manner of an "I", a comma, a parenthesis, a fraction bar, etc. In other words, the length of the fin is greater in the longitudinal direction Y than in its two other directions. More precisely, at least one of the fins extends in 3 directions:

[0017] - a thickness, along the stacking direction Z - a width, along the longitudinal direction X

[0018] - a length, along or projected along the transverse direction Y.

[0019] The thickness is then preferably less than the width, which is itself less than the length. For example, the width is at least half as large as the length and / or the thickness is at least ten times less large than the width.

[0020] The invention also relates to a fuel cell comprising the stack as defined above.

[0021] According to other advantageous aspects of the invention, one or more of the following characteristics are provided, taken individually or in all technically possible combinations.

[0022] Preferably, the inner base end of said at least one primary inner fin is offset in the longitudinal direction relative to the outer free end of said at least one primary inner fin.

[0023] Preferably, the internal free end of said at least one primary external fin is offset in the longitudinal direction relative to the external base end of said at least one primary external fin.

[0024] Preferably, a plurality of primary outer fins and a plurality of primary inner fins are provided and are distributed alternately along the primary rim. Said primary outer fins are then preferably distinct and spaced apart from each other and / or said plurality of primary inner fins are then preferably distinct and spaced apart from each other.

[0025] Preferably, said at least one primary external fin and the primary peripheral seal are arranged on the same flat area of ​​the primary rim.

[0026] Preferably, said at least one primary internal fin is distant from the primary peripheral seal in the transverse direction.

[0027] Preferably, the primary circulation field comprises dikes and channels, which are distributed alternately in the transverse direction. Preferably, each dike and each channel is generally oriented parallel to the longitudinal direction. Preferably, each channel is bordered by two of the dikes in the transverse direction. Preferably, each dike is in relief in the stacking direction relative to the channel which is bordered by said dike. Preferably, the dikes comprise a last dike which delimits the primary circulation field and by means of which the primary rim, on which said at least one primary external fin is arranged, is connected to the primary circulation field. Preferably, the last dike is distant from the internal free end of said at least one primary external fin in the transverse direction.Preferably, said at least one primary internal fin, the primary rim and the primary circulation field are formed by the same plastically deformed sheet constituting the primary separator.

[0028] Preferably: the stack comprises the membrane electrode assembly, which extends perpendicular to the stacking direction, which is superimposed with the primary separator, such that the membrane electrode assembly is arranged in the stacking direction relative to the primary separator, the membrane electrode assembly comprising:

[0029] • an exchange layer, which comprises a central zone and the peripheral zone which extends the exchange layer beyond the central zone in the transverse direction, the exchange layer comprising, at least in the central zone, a proton exchange polymer membrane, and

[0030] • the primary gas diffusion layer, interposed, in the stacking direction, between the primary circulation field and the central zone; the internal base end bears against the primary gas diffusion layer in the stacking direction; the internal free end faces the peripheral zone in the stacking direction; said at least one primary external fin is interposed between the primary rim and the membrane electrode assembly in the stacking direction; and the internal free end is interposed between the primary rim and the primary gas diffusion layer in the stacking direction.

[0031] Preferably, the stack further comprises a secondary separator, which extends perpendicular to the stacking direction, which is superimposed with the membrane-electrode assembly such that the secondary separator is arranged in the stacking direction relative to the membrane-electrode assembly, and which comprises: a secondary circulation field, for guiding a secondary reactive fluid flow, and a secondary rim, which extends the secondary separator beyond the secondary circulation field in the transverse direction. Preferably, the membrane-electrode assembly comprises a secondary gas diffusion layer, interposed, in the stacking direction, between the central zone and the secondary circulation field. Preferably, the stack further comprises a secondary peripheral seal, which is interposed between the peripheral zone and the secondary rim in the stacking direction.Preferably, the stack further comprises at least one secondary external fin, which is integral with the secondary peripheral seal, which is interposed between the membrane-electrode assembly and the secondary rim along the stacking direction, and which comprises: an external base end, connected to the secondary peripheral seal, and an internal free end, interposed between the secondary gas diffusion layer and the secondary rim along the stacking direction.

[0032] Preferably, the outer base end of said at least one secondary outer fin is offset in the longitudinal direction relative to the inner free end of said at least one secondary outer fin.

[0033] Preferably, said at least one primary internal fin and said at least one secondary external fin are arranged in an aligned manner along the stacking direction, at least for a respective intersection portion of said at least one primary internal fin and said at least one secondary external fin.

[0034] Preferably, the peripheral zone of the exchange layer is formed by a holding frame which has an internal peripheral portion delimiting the central zone occupied by the proton exchange polymer membrane, the holding frame being assembled by the internal peripheral portion to an external peripheral portion of the proton exchange polymer membrane. Preferably, the primary gas diffusion layer, the holding frame and the secondary gas diffusion layer form an excess thickness zone, where the primary gas diffusion layer, the holding frame and the secondary gas diffusion layer are superimposed along the stacking direction.Preferably, the primary gas diffusion layer, the proton exchange polymer membrane and the secondary gas diffusion layer form a zone of reduced thickness, where the primary gas diffusion layer, the proton exchange polymer membrane and the secondary gas diffusion layer are superimposed along the stacking direction. Preferably, along the stacking direction, a thickness of the membrane-electrode assembly, measured in the excess thickness zone, is greater than a thickness of the membrane-electrode assembly measured in the zone of reduced thickness. Preferably, the excess thickness zone is interposed, along the stacking direction, between the intersection portion of said at least one primary internal fin and the intersection portion of said at least one secondary external fin.

[0035] Preferably, each internal fin is connected to the circulation field only via its internal base end. In particular, each external free end is connected to the circulation field only via the internal base end. Preferably, each internal fin has the same width, measured in the longitudinal direction, over at least the majority of its length. Preferably, each external fin is connected to the peripheral seal only via its external base end. In particular, each internal free end is connected to the peripheral seal only via the external base end. Preferably, each external fin has the same width, measured in the longitudinal direction, over at least the majority of its length.

[0036] According to an embodiment independent of the invention described above, a stack is defined for a fuel cell, the stack defining a stacking direction, a transverse direction and a distinct longitudinal direction, and comprising a primary separator, which extends perpendicular to the stacking direction. The primary separator comprises a primary circulation field, for guiding a flow of primary reactive fluid, and a primary rim, which extends the primary separator beyond the primary circulation field in the transverse direction. The stack comprises a secondary separator, which extends perpendicular to the stacking direction and which comprises a secondary circulation field, for guiding a flow of secondary reactive fluid and a secondary rim, which extends the secondary separator beyond the secondary circulation field in the transverse direction.The stack comprises a membrane-electrode assembly, which extends perpendicular to the stacking direction, which is interposed between the primary separator and the secondary separator along the stacking direction, such that the membrane-electrode assembly is arranged in the stacking direction relative to the primary separator and the secondary separator is arranged in the stacking direction relative to the membrane-electrode assembly.The membrane electrode assembly comprises an exchange layer, which comprises a central zone and a peripheral zone which extends the exchange layer beyond the central zone in the transverse direction, the exchange layer comprising, at least in the central zone, a proton exchange polymer membrane, a primary gas diffusion layer, interposed, in the stacking direction, between the primary circulation field and the central zone, and a secondary gas diffusion layer, interposed, in the stacking direction, between the central zone and the secondary circulation field.The stack comprises at least one primary internal fin, integral with the primary separator, which projects from the primary rim in the stacking direction, and which comprises an internal base end, connected to the primary circulation field and bearing against the primary gas diffusion layer in the stacking direction, and an external free end, which is arranged so as to be opposite the peripheral zone in the stacking direction. The stack comprises a secondary peripheral seal, which is interposed between the peripheral zone and the secondary rim in the stacking direction. According to this independent embodiment of the invention, the stack further comprises at least one secondary external fin, integral with the secondary peripheral seal, which is interposed between the membrane-electrode assembly and the secondary rim in the stacking direction.Said at least one secondary external fin comprises an external base end, connected to the secondary peripheral seal and an internal free end, interposed between the secondary gas diffusion layer and the secondary rim in the stacking direction.

[0037] Preferably, for this independent embodiment, said at least one primary internal fin and said at least one secondary external fin are arranged in an aligned manner along the stacking direction, for at least a respective intersection portion of said at least one primary internal fin and said at least one secondary fin.

[0038] Preferably, for this independent embodiment, the outer free end of said at least one primary inner fin is offset in the longitudinal direction relative to the inner base end of said at least one primary inner fin. Preferably, the inner free end of said at least one secondary outer fin is offset in the longitudinal direction relative to the outer base end of said at least one secondary outer fin.

[0039] According to an embodiment independent of the invention described above, a stack is defined for a fuel cell, the stack defining a stacking direction, a transverse direction and a distinct longitudinal direction, and comprising:

[0040] - a primary separator, which extends perpendicular to the stacking direction and which comprises: a primary circulation field, for guiding a flow of primary reactive fluid, and a primary rim, which extends the primary separator beyond the primary circulation field in the transverse direction;

[0041] - a membrane-electrode assembly, which extends perpendicular to the stacking direction, which is superimposed with the primary separator, such that the membrane-electrode assembly is arranged in the stacking direction relative to the primary separator, the membrane-electrode assembly comprising: an exchange layer, which comprises a central zone and a peripheral zone which extends the exchange layer beyond the central zone in the transverse direction, the exchange layer comprising, at least in the central zone, a proton exchange polymer membrane, and a primary gas diffusion layer, interposed, in the stacking direction, between the primary circulation field and the central zone;- at least one primary internal fin, integral with the primary separator, which projects from the primary rim in the stacking direction, and which comprises: an internal base end, connected to the primary circulation field and bearing against the primary gas diffusion layer in the stacking direction, and an external free end, which is arranged so as to be opposite the peripheral zone in the stacking direction; and a primary peripheral seal, which is interposed between the primary rim and the peripheral zone in the stacking direction.;

[0042] According to the invention, the stack further comprises at least one primary external fin, which is integral with the primary peripheral seal, which is interposed between the primary rim and the membrane-electrode assembly in the stacking direction, said at least one primary internal fin and said at least one primary external fin being offset from each other in the longitudinal direction, and said at least one primary external fin comprising:

[0043] - an external base end, connected to the primary peripheral seal; and an internal free end, interposed between the primary rim and the primary gas diffusion layer along the stacking direction.

[0044] Furthermore, any characteristic of the invention as defined above is applicable to these independent embodiments and vice versa.

[0045] The invention will appear more clearly on reading the description which follows, given solely by way of non-limiting example, and made with reference to the drawings in which:

[0046] [Fig 1] Figure 1 is a perspective view of a fuel cell comprising a stack according to the invention.

[0047] [Fig 2] Figure 2 includes a front view of a primary separator and a back view of a membrane-electrode assembly belonging to the stack of Figure 1.

[0048] [Fig 3] Figure 3 includes a back view of a secondary separator and a front view of the membrane-electrode assembly belonging to the stack of the previous figures.

[0049] [Fig 4] Figure 4 is a partial cross-section of the stack along the plane

[0050] IV- IV shown in figures 2 and 3.

[0051] [Fig 5] Figure 5 is a partial cross-section of the stack taken along the plane

[0052] VV shown in Figures 2 and 3.

[0053] [Fig 6] Figure 6 is a partial front view of the primary separator, also showing, in broken lines, certain characteristics of the membrane-electrode assembly superimposed on the primary separator and of the secondary separator superimposed on the membrane-electrode assembly. Figure 6 also shows section planes IV- IV and V- V.

[0054] Figure 1 shows a fuel cell 1, comprising a stack 2 of electrochemical cells 4, as well as two terminal plates 3. The fuel cell 1 is preferably intended to equip a vehicle, in particular to electrically power an electric motor intended for traction or propulsion of the vehicle.

[0055] Stack 2 defines a longitudinal direction X, a transverse direction Y and a stacking direction Z. As illustrated, each of these directions X, Y and Z is oriented, that is to say it is directed in a direction symbolized by an arrow in the figures. These directions are perpendicular to each other and distinct. Preferably, the transverse direction Y is directed upwards when the stack is in use.

[0056] The stack 2 is interposed between the two end plates 3 along the stacking direction Z and is sandwiched between said end plates 3. The stack 2 is supplied, advantageously via one of the end plates 3, with a primary reactive fluid, a secondary reactive fluid and, preferably, a cooling fluid. The primary reactive fluid and the secondary reactive fluid react chemically within the stack 2 to generate electricity. The primary and secondary reactive fluids, loaded with reaction products, and the cooling fluid heated by the stack 2, are also discharged from the stack 2, for example via the same end plate 3.

[0057] The primary reactive fluid may be an anodic fluid, preferably a hydrogen-containing gas. The secondary reactive fluid may be a cathodic fluid, preferably an oxygen-containing gas, such as air. Alternatively, the primary reactive fluid is the cathodic fluid while the secondary reactive fluid is the anodic fluid. The cooling fluid is advantageously a coolant.

[0058] The stack 2 can comprise several hundred electrochemical cells 4. Each electrochemical cell 4 comprises, successively along the stacking direction Z, a primary separator 10, a primary peripheral seal 70, a membrane-electrode assembly 30, a secondary peripheral seal 90 and a secondary separator 50. These elements are shown separately in Figures 2 and 3, and assembled in Figures 4 and 5.

[0059] Within each cell 4 a chemical reaction occurs between the primary and secondary reactive fluids, creating an electrical potential difference between the primary separator 10 and the secondary separator 50. Here, for each cell 4, the primary separator 10 is an anodic separator while the secondary separator 50 is a cathodic separator, but the reverse could be expected.

[0060] The primary separator 10 has a general plate shape, which extends along a plane perpendicular to the stacking direction Z. The primary separator 10 is metallic, or made of another electrically conductive material. Preferably, the primary separator 10 is formed by a single sheet, extending along the X and Y directions and stamped along the stacking direction Z. Functionally, the primary separator 10 can be referred to as the “polar plate” of the cell 4.

[0061] Figure 2 shows the primary separator 10, of which a reaction face 11 is visible. The reaction face 11 is turned in the stacking direction Z. The primary separator 10 comprises a primary circulation field 12, two primary edges 13 and two end edges 14, forming the reaction face 11.

[0062] The primary circulation field 12 is disposed in the center of the primary separator 10, being formed on the reaction face 11. During use, the primary circulation field 12 guides a flow FH of primary reactive fluid along the reaction face 11, circulating, overall, in a direction opposite to the direction X.

[0063] In more detail, the primary circulation field 12 comprises dikes 17 and channels 18, which extend, overall, parallel to the X direction and which are distributed alternately along the Y direction. The dikes 17 and the channels 18 are here rectilinear along the X direction, but may have other shapes, in particular with undulations along the Y direction. Each channel 18 is bordered by two of the dikes 17 along the transverse direction Y, so that the dikes 17 delimit the channels 18 between them, in pairs. Each dike 17 is in relief along the stacking direction Z relative to the channel 18 which is bordered by said dike 17. As shown in Figures 4 and 5, the flow FH is guided by the dikes 17 and the channels 18 so as to divide to circulate inside each channel 18 in the opposite direction to the longitudinal direction X.Preferably, the dikes 17 and the channels 18 are formed directly by stamping the sheet metal forming the primary separator 10. Preferably, the bottom of the channels 18 extends in the same plane as the edges 13 and / or 14 while the top of the dikes 17 is in relief relative to the edges 13 and / or 14 along the stacking direction Z.

[0064] With respect to the longitudinal direction X, the two end edges 14 are arranged on either side of the circulation field 12. Each end edge 14 extends individually in the transverse direction Y to serve the circulation field 12 over its entire width. One of the end edges 14 extends the primary separator 10 beyond the primary circulation field 12, in the direction X, while the other end edge 14 extends the primary separator 10 beyond the primary circulation field 12, in the opposite direction.

[0065] With respect to the transverse direction Y, the two primary edges 13 are arranged on either side of the circulation field 12. Each primary edge 13 extends individually in the longitudinal direction X so as to run along the circulation field 12 over its entire length, and to connect the two edges 14 together. One of the primary edges 13 extends the primary separator 10 beyond the primary circulation field 12, in the direction Y, while the other primary edge 13 extends the primary separator 10 beyond the primary circulation field 12, in the opposite direction. Each primary edge 13 is advantageously a strip elongated in the direction X and with a certain width in the direction Y. Each end edge 14 is advantageously a strip elongated in the direction Y and with a certain width in the direction X.In particular, one of the primary edges 13, shown in Figures 4 and 5, extends from the last of the dikes 17 of the circulation field 12 in the direction Y. The other primary edge 13, visible in Figure 2, extends from the last of the dikes 17 of the circulation field 12 in the opposite direction to the direction Y. These last two dikes delimit between them the circulation field 12, in the direction Y.

[0066] The secondary separator 50 has a general plate shape, which extends along a plane perpendicular to the stacking direction Z. The secondary separator 50 is metallic, or made of another electrically conductive material. Preferably, the secondary separator 50 is formed by a single sheet, extending along the X and Y directions and stamped in the opposite direction to the stacking direction Z. Functionally, the secondary separator 50 can be referred to as the “polar plate” of the cell 4.

[0067] Figure 3 shows the secondary separator 50, of which a reaction face 51 is visible. The reaction face 51 is facing away from the stacking direction Z. The secondary separator 50 comprises a secondary circulation field 52, two secondary edges 53 and two end edges 54, forming the reaction face 51.

[0068] Preferably, the secondary circulation field 52 is opposite the primary circulation field 12 in the stacking direction Z. Preferably, the edges 53 and 54 are respectively aligned with the edges 13 and 14 in the stacking direction Z.

[0069] The secondary circulation field 52 is arranged in the center of the secondary separator 50, being formed on the reaction face 51. During use, the secondary circulation field 52 guides a flow FO of secondary reactive fluid along the reaction face 51, circulating, overall, in the longitudinal direction X. In more detail, the secondary circulation field 52 comprises dikes 57 and channels 58, which extend, overall, parallel to the direction X and which are distributed alternately in the direction Y. The dikes 57 and the channels 58 are here rectilinear in the direction X, but may have other shapes, in particular with undulations in the direction Y. Each channel 58 is bordered by two of the dikes 57 in the transverse direction Y, so that the dikes 57 delimit the channels 58 between them, in pairs.Each dam 57 is in relief in the opposite direction to the stacking direction Z relative to the channel 58 which is bordered by said dam 57. As shown in Figures 4 and 5, the flow FO is guided by the dams 57 and the channels 58 so as to divide to circulate inside each channel 58 in the longitudinal direction X. Preferably, the dams 57 and the channels 58 are formed directly by stamping the sheet metal forming the secondary separator 50. Preferably, the bottom of the channels 58 extends in the same plane as the edges 53 and / or 54 while the top of the dams 57 is in relief relative to the edges 53 and / or 54 in the opposite direction to the stacking direction Z.

[0070] With respect to the longitudinal direction X, the two end edges 54 are arranged on either side of the circulation field 52. Each end edge 54 extends individually in the transverse direction Y to serve the circulation field 52 over its entire width. One of the end edges 54 extends the secondary separator 50 beyond the secondary circulation field 52, in the direction X, while the other end edge 54 extends the secondary separator 50 beyond the secondary circulation field 52, in the opposite direction.

[0071] With respect to the transverse direction Y, the two secondary edges 53 are arranged on either side of the secondary circulation field 52. Each secondary edge 53 extends individually in the longitudinal direction X so as to run along the secondary circulation field 52 over its entire length, and to connect the two edges 54 together. One of the secondary edges 53 extends the secondary separator 50 beyond the secondary circulation field 52, in the direction Y, while the other secondary edge 53 extends the secondary separator 50 beyond the secondary circulation field 52, in the opposite direction. Each secondary edge 53 is advantageously a strip elongated in the direction X and with a certain width in the direction Y. Each end edge 54 is advantageously a strip elongated in the direction Y and with a certain width in the direction X.In particular, one of the secondary edges 53, shown in Figures 4 and 5, extends from the last of the dikes 57 of the circulation field 52 in the direction Y. The other secondary edge 53, visible in Figure 3, extends from the last of the dikes 57 of the circulation field 52 in the opposite direction to the direction Y. These last two dikes delimit between them the circulation field 52, in the direction Y.

[0072] The membrane-electrode assembly 30, which is shown in Figures 2 to 5, has a general plate shape, which extends along a plane perpendicular to the stacking direction Z. The membrane-electrode assembly 30 is superimposed with the primary separator 10 of the same cell 4, along the stacking direction Z, that is to say that the membrane-electrode assembly 30 and the primary separator 10 are stacked along the direction Z, in particular with superposition of their respective contours. Thus superimposed, the membrane-electrode assembly 30 is arranged in the stacking direction Z relative to the primary separator 10, as visible in FIGS. 4 and 5. The secondary separator 50 is superimposed with the membrane-electrode assembly 30 of the same cell 4 along the stacking direction Z, that is to say that the membrane-electrode assembly 30 and the secondary separator 50 are stacked along the direction Z, in particular with superposition of their respective contours.Thus superimposed, the secondary separator 50 is arranged in the stacking direction Z relative to the membrane-electrode assembly 30 and relative to the primary separator 10 of the same cell 4. In other words, for each cell 4, the membrane-electrode assembly 30 is interposed between the primary separator 10 and the secondary separator 50 along the direction Z.

[0073] The membrane-electrode assembly 30 comprises an exchange layer 33, a primary gas diffusion layer 34 and a secondary gas diffusion layer 35. The exchange layer 33 comprises a proton exchange polymer membrane 38 and a holding frame 39, which together constitute a central zone 36 of the exchange layer 33 and a peripheral zone 37 of the exchange layer 33.

[0074] The membrane-electrode assembly 30 has a primary face 31, shown in particular in FIG. 2, facing in the opposite direction to the stacking direction Z towards the immediately adjacent primary separator 10, belonging to the same cell 4. The primary face 31 is formed by the peripheral zone 37 and the primary gas diffusion layer 34, which overlap locally. The membrane-electrode assembly 30 has a secondary face 32, shown in particular in FIG. 3, facing in the direction Z towards the immediately adjacent secondary separator 50. The secondary face 32 is formed by the peripheral zone 37 and the secondary gas diffusion layer 35, which overlap locally.

[0075] In the present example, the gas diffusion primer layer 34 and the gas diffusion secondary layer 35 are of the same size, so that their outer edge is superimposed along the Z direction, as shown in FIG. 4. However, provision may be made for them not to be of the same size, so that their respective outer edge is offset from each other.

[0076] The holding frame 39 and the proton exchange membrane 38 extend along the same plane perpendicular to the stacking direction Z, the holding frame 39 surrounding the proton exchange membrane 38 over its entire periphery.

[0077] The holding frame 39 is for example formed by two polymer films superimposed along the stacking direction Z. In the present example, the holding frame 39 forms the peripheral zone 37 of the exchange layer 33. The holding frame 39, and therefore the peripheral zone 37, advantageously extends around the entire periphery of the assembly 30, in particular forming an external peripheral edge of the assembly 30.

[0078] The holding frame 39 has an internal peripheral portion 40, which delimits, inside the holding frame 39, an internal window, here of rectangular shape. This internal window occupies the central zone 36, which is therefore delimited by the internal peripheral portion 40 of the holding frame 39. At the internal peripheral portion 40, the holding frame 39 preferably forms an internal peripheral groove 45, which opens onto the internal window.

[0079] Parallel to the transverse direction Y, on one side of the central zone 36 shown in Figures 4 and 5, the peripheral zone 37 extends the exchange layer 33 beyond the central zone 36 in the transverse direction Y. On the opposite side of the central zone 36, the peripheral zone 37 extends the exchange layer 33 beyond the central zone 36 in the opposite direction to the transverse direction Y. Similarly, parallel to the longitudinal direction X, on one side of the central zone 36, the peripheral zone 37 extends the exchange layer 33 beyond the central zone 36 in the longitudinal direction X. On the opposite side of the central zone 36, the peripheral zone 37 extends the exchange layer 33 beyond the central zone 36 in the opposite direction to the longitudinal direction X.

[0080] The holding frame 39 is for example formed by two polymer films superimposed along the stacking direction Z, the two polymer films being in contact with each other except for the internal peripheral portion 40 where the polymer films are distant to delimit the internal peripheral groove 45.

[0081] The central zone 36 is entirely occupied by the proton exchange membrane 38. The proton exchange membrane 38 has an outer peripheral portion 41, which extends over its entire circumference, giving the membrane 38, for example, a rectangular shape. Preferably, the outer peripheral portion 41 extends beyond the central zone 36, encroaching on the peripheral zone 37. In the example, the outer peripheral portion 41 is received in the inner peripheral groove 45. The proton exchange membrane 38 and the holding frame 39 are assembled with each other, in that the outer peripheral portion 41 and the inner peripheral portion 40 are assembled. For example, as illustrated in FIGS. 4 and 5, the outer peripheral portion 41 is received inside the inner peripheral portion 40 of the holding frame 39, here in the inner peripheral groove 45.In particular, the inner peripheral portion 40 pinches the outer peripheral portion 41 along the stacking direction Z at the inner peripheral groove 45. To form the inner peripheral groove 45, the holding frame 39 divides into two locally at the inner peripheral portion 40, to extend on either side of the outer peripheral portion 41 of the membrane 38, along the stacking direction Z. For the case where the holding frame 39 is formed by the two polymer films, it can be provided that the polymer films receive between them the outer peripheral portion 41 of the proton exchange polymer membrane 38, at the inner peripheral portion 40.

[0082] While the holding frame 39 and the membrane 38 have a thickness, measured along the Z direction, which is substantially constant and equal outside the inner 40 and outer 41 peripheral portions, said inner 40 and outer 41 peripheral portions form a slight local excess thickness along the Z direction, at the location where they overlap and / or are received one within the other. Optionally, at least for the central zone 36, the proton exchange membrane 38 is covered, on the primary face 31 side, by a layer of catalyst and on the secondary face 32 side, by another layer of catalyst.

[0083] In the opposite direction to the stacking direction Z, the primary gas diffusion layer 34 covers the central zone 36, including the membrane 38, on the side of the primary face 31, and preferably also covers a portion of the peripheral zone 37, as shown in FIGS. 4 and 5. Preferably, the primary gas diffusion layer 34 covers the inner 40 and outer 41 peripheral portions, where the holding frame 39 and the membrane 38 overlap and / or are received one inside the other. Preferably, the primary gas diffusion layer 34 extends, in the transverse direction Y, beyond the outer portion 41 of the membrane 38, between the membrane 38 and the seal 70.

[0084] In the stacking direction Z, the secondary gas diffusion layer 35 covers the central zone 36, including the membrane 38, on the side of the secondary face 32, and preferably also covers a part of the peripheral zone 37. Preferably, the secondary gas diffusion layer 35 covers the inner 40 and outer 41 peripheral portions, where the holding frame 39 and the membrane 38 overlap and / or are received one inside the other. Preferably, the secondary gas diffusion layer extends, in the transverse direction Y, beyond the outer peripheral portion 41 of the membrane 38, between the membrane 38 and the seal 90.

[0085] Preferably, the membrane electrode assembly 30 has a zone 42, called the “internal extra thickness zone”, at the location where the gas diffusion layers 34 and 35, the internal peripheral portion 40 of the holding frame 39 and the external peripheral portion 41 of the membrane 38 overlap.

[0086] Preferably, the membrane electrode assembly 30 has a zone 47, called the “external extra thickness zone”, at the location where the gas diffusion layers 34 and 35 and the holding frame 39, without the interposition of the membrane 38. Along the transverse direction Y, the zone 47 follows the zone 42.

[0087] Preferably, the membrane electrode assembly 30 has a zone 46, called the “zone of reduced thickness”, at the location where the gas diffusion layers 34 and 35 and the membrane 38 overlap, without the interposition of the holding frame 39. Along the transverse direction Y, the zone 42 follows the zone 46.

[0088] Preferably, along the Z direction, a thickness of the membrane-electrode assembly 30 measured in the excess thickness zone 42 is greater than a thickness of the membrane-electrode assembly 30 measured in the lesser thickness zone 46.

[0089] Preferably, along the Z direction, a thickness of the membrane-electrode assembly 30 measured in the excess thickness zone 47 is greater than a thickness of the membrane-electrode assembly 30 measured in the lesser thickness zone 46.

[0090] Preferably, along the Z direction, a thickness of the membrane-electrode assembly 30 measured in the excess thickness zone 42 is slightly greater than a thickness of the membrane-electrode assembly 30 measured in the excess thickness zone 47.

[0091] The exchange layer 33 is therefore interposed between the gas diffusion layers 34 and 35, along the stacking direction Z, at least for the central zone 36.

[0092] Along the stacking direction Z, the reaction face 11 of the primary separator 10 faces the primary face 31 of the membrane-electrode assembly 30. In particular, the primary edges 13 and the end edges 14 of the primary separator 10 are arranged, along the stacking direction Z, opposite but at a distance from the peripheral zone 37, in particular from the holding frame 39.

[0093] The primary gas diffusion layer 34 is interposed, along the stacking direction Z, between the primary circulation field 12 and the central zone 36. In particular, the primary gas diffusion layer 34 bears against the dikes 17 in the opposite direction to the stacking direction Z, so as to delimit the channels 18 along the direction Z, and so as to allow electrical conduction between the primary gas diffusion layer 34 and the primary separator 10. The flow of primary reactive fluid FH conducted by each channel 18 is therefore in contact with the primary gas diffusion layer 34. All or part of the flow FH therefore diffuses into the primary gas diffusion layer 34.

[0094] In the opposite direction to the stacking direction Z, the reaction face 51 of the secondary separator 50 faces the secondary face 32 of the membrane-electrode assembly 30. In particular, the secondary edges 53 and the end edges 54 of the secondary separator 50 are arranged, in the stacking direction Z, opposite and at a distance from the peripheral zone 37, in particular from the holding frame 39.

[0095] The secondary gas diffusion layer 35 is interposed, along the stacking direction Z, between the secondary circulation field 52 and the central zone 36. In particular, the secondary gas diffusion layer 35 bears against the dikes 57 along the stacking direction Z, so as to delimit the channels 58 in the opposite direction to the direction Z, and so as to allow electrical conduction between the secondary gas diffusion layer 35 and the secondary separator 50. The flow of secondary reactive fluid FO conducted by each channel 58 is therefore in contact with the secondary gas diffusion layer 35. All or part of the flow FO therefore diffuses into the secondary gas diffusion layer 35.

[0096] The primary reactive fluid having diffused into the primary gas diffusion layer 34 and the secondary reactive fluid having diffused into the secondary gas diffusion layer 35 can then, without passing through the membrane 38, exchange protons through the membrane 38, which creates an electrical charge imbalance, bringing the separators 10 and 50 to a different electrical potential. In other words, the membrane 38 is the seat of an electrochemical reaction for the cell 4, by means of which the cell generates electricity, heat and reaction products by consuming the primary and secondary reactive fluids.

[0097] An opening 15H, for supplying the primary circulation field 12 with primary reactive fluid, is provided through one of the end rims 14 arranged in the X direction relative to the other end rim 14. The opening 15H is fluidically connected to the face 11, so that a flow of primary reactive fluid circulating through the opening 15H, parallel to the Z direction, supplies the face 11 with primary reactive fluid.

[0098] An opening 16H, for evacuating primary reactive fluid from the circulation field 12, is provided through the other end rim 14. The opening 16H is fluidically connected to the face 11, so that primary reactive fluid present on the face 11 can be evacuated through the opening 15H, parallel to the direction Z.

[0099] Preferably, the 15H opening is offset from the 16H opening along the transverse direction Y, so as to be higher than the 16H opening in use. The 16H opening then benefits from gravity to facilitate the evacuation of the primary reactive fluid and / or the reaction products formed in the primary circulation field.

[0100] Optionally, the reaction face 11 comprises collectors, sometimes called homogenization fields or distribution fields, not shown. In certain embodiments, these homogenization fields form, for example, channels on the face 11, arranged in a fan shape, one of the homogenization fields fluidly connecting the opening 15H to the circulation field 12, and the other homogenization field fluidly connecting the circulation field 12 to the opening 16H.

[0101] Other openings 150, 160, 150 and 160 are provided through the end edges 14.

[0102] The opening 150 is an opening in which a flow of secondary reactive fluid circulates, parallel to the direction Z, for supplying the stack 2. The opening 150 passes through the primary separator 10 parallel to the direction Z without being fluidically connected to the face 11, that is to say without supplying the face 11 with the secondary reactive fluid. For this, on the face 11, the opening 150 is advantageously surrounded by a closed-contour seal, interposed between the primary separator 10 and the membrane-electrode assembly 30.

[0103] Preferably, the opening 150 is located on the extreme edge 14 opposite the opening 15H, being aligned with the opening 15H in the longitudinal direction X.

[0104] The opening 160 is an opening in which a flow of secondary reactive fluid circulates, parallel to the direction Z, for the evacuation of the stack 2. The opening 160 passes through the primary separator 10 parallel to the direction Z without being fluidically connected to the face 11. For this, on the face 11, the opening 160 is advantageously surrounded by a closed-contour seal, interposed between the primary separator 10 and the membrane-electrode assembly 30.

[0105] Preferably, the openings 150 and 160 are each arranged on one of the end rims 14. Preferably, the opening 160 is located on the end rim 14 opposite the opening 150. Preferably, the opening 160 is offset in the longitudinal direction X relative to the opening 150. Preferably, the opening 150 is offset relative to the opening 160 in the transverse direction Y, so as to be higher than the opening 160 in use.

[0106] The opening 150 is an opening in which a flow of cooling fluid circulates, parallel to the direction Z, for supplying the stack 2. The opening 150 passes through the primary separator 10 parallel to the direction Z without being fluidically connected to the face 11. For this, on the face 11, the opening 15C is advantageously surrounded by a closed-contour seal, interposed between the primary separator 10 and the membrane-electrode assembly 30.

[0107] The opening 16C is an opening in which a flow of cooling fluid circulates, parallel to the direction Z, for the evacuation of the stack 2. The opening 16C passes through the primary separator 10 parallel to the direction Z without being fluidically connected to the face 11. For this, on the face 11, the opening 16C is advantageously surrounded by a closed-contour seal, interposed between the primary separator 10 and the membrane-electrode assembly 30.

[0108] Preferably, the openings 15C and 16C are each arranged on one of the end rims 14. Preferably, the opening 16C is located on the end rim 14 opposite relative to the opening 15C, being aligned with the opening 15C in the longitudinal direction X. For example, the opening 15C is offset in the longitudinal direction X relative to the opening 16C. Preferably, the opening 15C is arranged between the openings 15H and 160 carried by the same end rim 14. Preferably, the opening 16C is arranged between the openings 150 and 16H carried by the same end rim 14.

[0109] An opening 550, for supplying the secondary circulation field 52 with secondary reactive fluid, is provided through one of the end edges 54 arranged in the opposite direction to the X direction relative to the other end edge 54. The opening 550 is aligned with the opening 150 along the stacking direction Z, the same flow of secondary reactive fluid circulating through these openings 150 and 550. The opening 550 is fluidically connected to the face 51, so that a flow of secondary reactive fluid circulating through the opening 550, parallel to the Z direction, supplies the face 51 with secondary reactive fluid.

[0110] An opening 560, for evacuating secondary reactive fluid from the circulation field 52, is provided through the other end rim 54. The opening 560 is aligned with the opening 160 along the stacking direction Z, the same flow of secondary reactive fluid circulating through these openings 160 and 560. The opening 560 is fluidically connected to the face 51, so that secondary reactive fluid present on the face 51 can be evacuated through the opening 560, parallel to the direction Z.

[0111] Preferably, the opening 550 is offset relative to the opening 560 in the transverse direction Y, so as to be higher than the opening 560 in use. The opening 560 then benefits from gravity to facilitate the evacuation of the secondary reactive fluid and / or the reaction products formed in the secondary circulation field. Optionally, the reaction face 51 comprises collectors, sometimes called homogenization fields or distribution fields, not shown. In certain embodiments, these homogenization fields form channels on the face 51, arranged in a fan shape, one of the homogenization fields fluidly connecting the opening 550 to the circulation field 52, and the other homogenization field fluidly connecting the circulation field 52 to the opening 560.

[0112] Other openings 55H, 56H, 550 and 560 are provided through the end edges 54. These other openings 55H, 56H, 55C and 56C are respectively aligned, along the stacking direction Z, with the openings 15H, 16H, 150 and 160.

[0113] The opening 55H is an opening in which the flow of primary reactive fluid circulates, which also circulates in the opening 15H. The opening 55H passes through the secondary separator 50 parallel to the Z direction without being fluidically connected to the face 51, i.e. without supplying the face 51 with the primary reactive fluid. For this purpose, on the face 51, the opening 55H is advantageously surrounded by a closed-contour seal, interposed between the membrane-electrode assembly 30 and the secondary separator 50.

[0114] Preferably, the opening 55H is located on the extreme edge 54 opposite the opening 550, being aligned with the opening 550 in the longitudinal direction X.

[0115] The opening 56H is an opening in which the same flow of primary reactive fluid circulates, parallel to the Z direction as for the opening 16H. The opening 56H passes through the secondary separator 50 parallel to the Z direction without being fluidically connected to the face 51. For this, on the face 51, the opening 56H is advantageously surrounded by a closed-contour seal, interposed between the membrane-electrode assembly 30 and the secondary separator 50.

[0116] Preferably, the openings 55H and 56H are each arranged on one of the end rims 54. Preferably, the opening 56H is located on the opposite end rim 14 relative to the opening 55H. Preferably, the opening 55H is offset in the longitudinal direction X relative to the opening 56H. Preferably, the opening 55H is offset relative to the opening 56H in the transverse direction Y, so as to be higher than the opening 56H in use.

[0117] The opening 55C is an opening in which the same flow of cooling fluid circulates as that of the opening 15C, parallel to the Z direction. The opening 55C passes through the secondary separator 50 parallel to the Z direction without being fluidically connected to the face 51. For this purpose, on the face 51, the opening 55C is advantageously surrounded by a closed-contour seal, interposed between the membrane-electrode assembly 30 and the secondary separator 50. The opening 56C is an opening in which the same flow of cooling fluid circulates as that of the opening 16C, parallel to the Z direction. The opening 56C passes through the secondary separator 50 parallel to the Z direction without being fluidically connected to the face 51. For this purpose, on the face 51, the opening 56C is advantageously surrounded by a closed-contour seal, interposed between the membrane-electrode assembly 30 and the secondary separator 50.

[0118] Preferably, the openings 55C and 56C are each arranged on one of the end rims 54. Preferably, the opening 56C is located on the end rim 14 opposite relative to the opening 55C, being aligned with the opening 15C in the longitudinal direction X. For example, the opening 55C is offset in the longitudinal direction X relative to the opening 56C. Preferably, the opening 55C is arranged between the openings 55H and 560 carried by the same end rim 54. Preferably, the opening 56C is arranged between the openings 550 and 56H carried by the same end rim 54.

[0119] The peripheral zone 37 of the membrane-electrode assembly 30, here the holding frame 39, comprises openings 43H, 430, 43C, 44H, 440 and 44C, passing through in the stacking direction Z. The opening 43H fluidly connects the openings 15H and 55H in the Z direction, being aligned with the latter. The opening 44H fluidly connects the openings 16H and 56H in the Z direction, being aligned with the latter. The opening 430 fluidly connects the openings 150 and 550 in the Z direction, being aligned with the latter. The opening 440 fluidly connects the openings 160 and 560 in the Z direction, being aligned with the latter. The opening 43C fluidly connects the openings 15C and 55C along the Z direction, being aligned with the latter. The opening 44C fluidly connects the openings 16C and 56C along the Z direction, being aligned with the latter.

[0120] The primary peripheral seal 70 forms a closed and continuous contour, which is in sealing contact with the face 11 of the primary separator 10 over its entire closed contour. Along the stacking direction Z, the primary peripheral seal 70 is interposed between the faces 11 and 31. Along the stacking direction Z, the primary peripheral seal 70 is interposed between, on the one hand, the edges 13 and 14 and, on the other hand, the peripheral zone 37. The peripheral seal 70 then encloses, inside itself, a sealed volume intended to contain primary reactive gas, this volume being delimited, along the stacking direction Z, by the primary separator 10 and the membrane-electrode assembly 30. The primary peripheral seal 70 aims to prevent leakage of primary reactive fluid out of the face 11, towards the periphery of the primary separator 10.For this, the primary peripheral seal 70 surrounds at least the circulation field 12 and the openings 15H and 16H serving the face 11, or even surrounds the openings 150, 160, 15C and 16C, as is the case here. In particular, the primary peripheral seal 70 extends successively along a first of the edges 14, then a first of the edges 13 adjacent to the first edge 14, then along the second edge 14 adjacent to this first edge 13, then along the second edge 13, to rejoin the first edge 14.

[0121] In practice, on the reaction face 11, part of the flow FH is likely to bypass the circulation field 12, by circulating along the primary edges 13, between the circulation field 12 and the primary peripheral seal 70.

[0122] The secondary peripheral seal 90 forms a closed and continuous contour, which is in sealing contact with the face 51 of the secondary separator 50 over its entire closed contour. Along the stacking direction Z, the secondary peripheral seal 90 is interposed between the faces 32 and 51. Along the stacking direction Z, the secondary peripheral seal 90 is interposed between, on the one hand, the peripheral zone 37 and, on the other hand, the edges 53 and 54. The peripheral seal 90 then encloses, inside itself, a sealed volume intended to contain secondary reactive gas, this volume being delimited, along the stacking direction Z, by the membrane-electrode assembly 30 and the secondary separator 50. The secondary peripheral seal 90 aims to prevent leakage of secondary reactive fluid out of the face 51, towards the periphery of the secondary separator 50.For this, the secondary peripheral seal 90 surrounds at least the circulation field 52 and the openings 550 and 560 serving the face 51, or even surrounds the openings 55H, 56H, 55C and 56C, as is the case here. In particular, the secondary peripheral seal 90 extends successively along a first of the edges 54, then a first of the edges 53 adjacent to the first edge 54, then along the second edge 54 adjacent to this first edge 53, then along the second edge 53, to rejoin the first edge 54.

[0123] In practice, on the reaction face 51, part of the FO flow is likely to bypass the circulation field 52, by circulating along the secondary edges 53, between the circulation field 52 and the secondary peripheral seal 90.

[0124] Alternatively, the exchange layer 33 is devoid of a holding frame. In this case, it can be provided that the proton exchange membrane 38 occupies not only the central zone 36, but also the peripheral zone 37. In this case, there are no extra thickness zones 42 and 47, and the openings 43H, 44H, 430, 440, 43C, 44C can be provided through the membrane 38 in the peripheral zone 37.

[0125] As shown in Figures 4 and 5, on the back of the reaction face 11, the primary separator 10 advantageously forms a cooling face 19. Similarly, on the back of the reaction face 51, the secondary separator 50 advantageously forms a cooling face 59. Within the stack 2, the cells 4 are successively superimposed along the stacking direction Z, in particular with the secondary separator 50 of a first cell 4 bearing against the primary separator 10 of the following cell 4. In particular, the cooling faces 19 and 59 bear against each other. Thus, bearing against each other, the secondary separator 50 and the primary separator 10 form a bipolar plate, brought to the same electrical potential during use. On the side of the faces 19 and 59, the separators 10 and 50 are supported for example by means of the edges 13 and 53, and the edges 14 and 54.The channels 18 and 58 formed in hollows on the side of the faces 11 and 51 give rise to the formation of corresponding dikes in relief on the side of the faces 19 and 53 between the separators 10 and 50, which can bear against each other. Likewise, the dikes 17 and 57 formed in relief on the side of the faces 11 and 51 give rise to the formation of corresponding hollow channels on the side of the faces 19 and 53, between the separators 10 and 50, forming a circulation field between the separators 10 and 50 for a flow of cooling fluid FC, as shown in FIGS. 4 and 5. On the side of the cooling faces 19 and 53, it is provided that the openings 15C, 43C and 55C supply the cooling field with cooling fluid and that the openings 16C, 44C and 56C discharge cooling fluid.On the other hand, the other openings 15H, 43H, 55H, 160, 440, 560, 150, 430, 550, 160, 440 and 560 do not open out, being for example surrounded by closed contour seals, interposed between the separators 10 and 50. Along the edges 13 and 53 and the edges 14 and 54, the separators 10 and 50 can be assembled to each other, for example by gluing, welding or brazing, or, in a variant not shown, they can simply rest against each other, preferably with the interposition of a peripheral sealing seal forming a closed and continuous contour along the edges 13 and 53 and the edges 14 and 54, to delimit the cooling field in a sealed manner.

[0126] As shown in Figures 2, 4 and 5, the primary separator 10 forms several primary internal fins 20A and 20B. In other words, the primary internal fins 20A and 20B are integral with the primary separator 10. The fins 20A and 20B are therefore formed from the same material as the primary separator 10, in the example a metallic material, and form a single piece in one piece with the primary separator 10. In particular, it is provided that the fins 20A and 20B are obtained by the same process as that which made it possible to form the dikes 17 and the channels 18, namely, for example, a stamping of the sheet metal constituting the primary separator 10.

[0127] The fins 20A and 20B are intended to limit the quantity of primary reactive fluid which bypasses the primary circulation field 12 and which would circulate along the edges 13. The primary internal fins 20A protrude, in relief along the stacking direction Z, from one of the primary edges 13, located in the transverse direction Y relative to the primary circulation field 12. Preferably, along the longitudinal direction X, the fins 20A are regularly spaced along the primary edge 13. The primary internal fins 20B protrude in relief along the stacking direction Z, from the other primary edge 13, being regularly spaced along the longitudinal direction X. The same number of fins 20A is preferably provided as fins 20B.

[0128] Each primary internal fin 20A and 20B comprises an internal base end 21 and an external free end 22, formed in relief along the stacking direction Z relative to the primary rim 13. For each fin 20A and 20B, the ends 21 and 22 are continuously connected, so that the fin 20A or 20B concerned is straight, or hook-shaped, or is bent from the end 21 to the end 22.

[0129] Each fin 20A and 20B is connected to the primary circulation field 12 via its internal base end 21. In particular, as shown in Figures 2, 4 and 5, for the fins 20A, the internal base end 21 is connected to the last dike 17 of the circulation field 12 along the Y direction. In particular, for the fins 20B, the internal base end 21 is connected to the last dike 17 of the circulation field 12, in the opposite direction to the Y direction.

[0130] As can be seen in Figures 2 and 6, each primary internal fin 20A, 20B is advantageously a local and point fin which preferentially projects from the last dam 17. In other words, each primary internal fin 20A 20B is attached to the last dam 17 by a point zone, distinct and distant from the attachment zone of another primary internal fin. In particular, each primary internal fin 20A 20B is attached to the last dam 17 by its internal base end 21.

[0131] As can be seen in Figures 2 and 6, each primary internal fin 20A 20B has a substantially elongated shape along the transverse direction Y. In fact, each primary internal fin 20A 20B extends along three directions:

[0132] - a thickness, following the stacking direction Z

[0133] - a width, along the longitudinal direction X

[0134] - a length, following the transverse direction Y.

[0135] The thickness is then preferably less than the width, which is itself less than the length. For example, the width is at least half as great as the length. The thickness is at least ten times less great than the width.

[0136] Each primary internal fin 20A, 20B is preferably “I” or comma-shaped as illustrated. Each fin 20A and 20B bears against the primary gas diffusion layer 34 in the stacking direction Z, at least for the internal base end 21.

[0137] For each fin 20A the external free end 22 is arranged in the Y direction relative to the internal base end 21, so as to be as close as possible to the primary peripheral seal 70. However, so that the peripheral seal 70 can be easily manufactured, in particular by overmolding, each primary internal fin 20A, and in particular the external free end 22, is distant from the primary peripheral seal 70, in particular in the transverse direction Y. As shown in FIGS. 4 and 5, the external free end 22 of the fin 20A extends beyond the central zone 36 in the transverse direction Y, and even preferably beyond the primary gas diffusion layer 34. Thus, the external free end 22 of the fin 20A is arranged so as to be opposite the peripheral zone 37 opposite the primary rim 13 on which this fin 20A is arranged.In the present example, the free end 22 is opposite the peripheral zone 37 with the interposition of the gas diffusion layer 34 between the peripheral zone 37 and the free end 22. Preferably, the external free end 22 is not in abutment against the gas diffusion layer 34. As better visible in FIG. 2, for each fin 20A, it is advantageously provided that the internal base end 21 is offset in the longitudinal direction X relative to the external free end 22.

[0138] For each fin 20B the internal base end 21 is arranged in the Y direction relative to the external free end 22, so that the external free end 22 is as close as possible to the primary peripheral seal 70. Here also, so that the peripheral seal 70 can be easily manufactured, each primary internal fin 20B is distant from the primary peripheral seal 70, in particular in the transverse direction Y. The external free end 22 of the fin 20B extends beyond the central zone 36 in the opposite direction to the transverse direction Y, and even preferentially beyond the primary gas diffusion layer 34. Thus, the external free end 22 of the fin 20B is arranged so as to be opposite the peripheral zone 37 opposite the primary rim 13 on which this fin 20B is arranged. Preferably, the external free end 22 does not bear against the gas diffusion layer 34.As better seen in Figure 2, for each fin 20B, it is advantageous to provide that the external free end 22 is offset in the longitudinal direction X relative to the internal base end 21.

[0139] Preferably, for each fin 20A or 20B, the fin forms a strip or dike, from the base end to the free end, which is bent or curved so that the free end is offset relative to the base end. For example, an offset may be provided, along the X direction, which corresponds to approximately a quarter of the wavelength of a corrugation formed by the dikes 17 of the circulation field 12. For example, this offset is between 4 and 5 millimeters. It may be provided that the angle of a straight line between the base end and the free end forms an angle of approximately 30 to 75 degrees relative to the X direction. Preferably, this description of the shape of the fin also applies to the other fins defined below.

[0140] As shown in Figures 2, 4 and 5, the cell 4 also comprises several primary external fins 71 A and 71 B, which are integral with the peripheral seal 70. In other words, the primary external fins 71 A and 71 B and the seal 70 form a single piece. The fins 71 A and 71 B are therefore formed from the same material as the primary peripheral seal 70, for example an elastomer. In particular, it is provided that the fins 71 A and 71 B are obtained by the same process as that which made it possible to form the primary peripheral seal 70, for example, overmolding on the face 11 of the primary separator 10, preferably in the same manufacturing step.

[0141] As can be seen in Figures 2 and 6, each primary external fin 71 A, 71 B is advantageously a local and point fin which projects from the peripheral seal 70. In other words, each primary external fin 71 A and 71 B is attached to the peripheral seal 70 by a point zone, distinct and distant from the attachment zone of another primary external fin. In particular, each primary external fin 71 A, 71 B is attached to the peripheral seal 70 by its internal base end 72.

[0142] As can be seen in Figures 2 and 6, each primary external fin 71 A, 71 B has an elongated shape along the transverse direction Y. In fact, each primary external fin 71 A, 71 B extends along three directions:

[0143] - a thickness, following the stacking direction Z

[0144] - a width, along the longitudinal direction X

[0145] - a length, following the transverse direction Y.

[0146] The thickness is then preferably less than the width, which is itself less than the length. For example, the width is at least half as great as the length. The thickness is at least ten times less great than the width.

[0147] Each primary outer fin 71 A, 71 B is preferably “I” or comma shaped, as illustrated.

[0148] The fins 71A and 71B are intended to limit the amount of primary reactive fluid that bypasses the primary circulation field 12 and that would circulate along the edges 13. The primary external fins 71A protrude, in relief along the stacking direction Z, from one of the primary edges 13, located in the transverse direction Y relative to the primary circulation field 12. Along the longitudinal direction X, the fins 71A are regularly spaced along the primary edge 13. Along the direction X, each fin 71A is offset relative to one of the fins 20A that precedes or succeeds it. Preferably, the fins 71A are alternated along the direction X with the fins 20A, as shown in FIG. 2. In other words, each fin 20A is immediately followed along the direction X by a fin 71A and vice versa.This alternation of fins 20A and 71A along the X direction makes it possible to effectively limit the quantity of reactive fluid which bypasses the circulation field 12, by forming baffles. Alternatively, a succession of a number N of fins 71A is provided, followed by the same number N of fins 20A, followed by the same number N of fins 71A and so on, where N is a natural whole number greater than or equal to two, such as two, three, four, five, or six. For example, when N = 2, there are two 71A fins followed by two 20A fins followed by two 71A fins. Alternatively, there is provided a succession of a number N1 of 71A fins, followed by a different number N2 of 20A fins, followed by a number N1 of 71A fins and so on, where N1 and N2 are each a natural whole number greater than or equal to two, such as two, three, four, five, or six.

[0149] The primary external fins 71 B project, in relief along the stacking direction Z, from the other primary rim 13, being regularly spaced along the longitudinal direction X, preferably also alternating with the fins 20B along the direction X. The same number of fins 71 A as fins 71 B is preferably provided. The primary external fins 71 A and 71 B project from their respective primary rim 13 so as to be interposed, along the stacking direction Z, between this primary rim 13 and the membrane-electrode assembly 30. In particular, for each fin 71 A and 71 B, a portion of the fin is interposed between the primary rim 13 and the primary gas diffusion layer 34.

[0150] Each primary external fin 71 A and 71 B comprises an external base end 72, by means of which the fin 71 A or 71 B is connected to the primary peripheral seal 70, and an internal free end 73, interposed between the primary rim 13 carrying this fin 71 A or 71 B and the primary gas diffusion layer 34. For each fin 71 A and 71 B, the ends 72 and 73 are continuously connected, so that the fin 71 A or 71 B concerned is straight, or hook-shaped, or is bent from the end 72 to the end 73.

[0151] As shown in Figures 4 and 5, it is possible to provide that the outer base end 72 is opposite, in the stacking direction Z, the peripheral zone 37 of the membrane-electrode assembly 30 with a clearance between the outer base end 72 and the peripheral zone 37 in the stacking direction Z. On the contrary, it is possible to provide that the end 72 is in abutment against the peripheral zone 37. For each fin 71A, the inner free end 73 is in abutment against the primary gas diffusion layer 34, extending at least in the excess thickness zone 47 in the opposite direction to the Y direction, or preferably extending in the excess thickness zone 42 or beyond the excess thickness zone 42 in the opposite direction to the Y direction.For each fin 71 B, the internal free end 73 bears against the primary gas diffusion layer 34, extending at least in the excess thickness zone 47 in the direction Y, or preferably extending in the excess thickness zone 42 or beyond the excess thickness zone 42 in the direction Y. In other words, for each fin 71 A, 71 B, the internal free end 73 is arranged inside towards the primary circulation field 12 relative to the excess thickness zone 42.

[0152] For each fin 71 A, the internal free end 73 is arranged in the opposite direction to the Y direction relative to the external base end 72, so as to be as close as possible to the circulation field 12. However, so that the fin 71 A can be easily manufactured, in particular by overmolding, each primary external fin 71 A, in particular the internal free end 73, is distant from the circulation field 12, in particular from the last dike 17 of the field 12 in the Y direction, as shown in FIGS. 2, 4 and 5. As best seen in FIG. 2, for each fin 71 A, it is advantageously provided that the internal free end 73 is offset in the longitudinal direction X relative to the external base end 72.

[0153] For each fin 71 B, the internal free end 73 is arranged in the direction Y relative to the external base end 72, so as to be as close as possible to the circulation field 12. Nevertheless, so that the fin 71 B can be easily manufactured, in particular by overmolding, each primary external fin 71 B, in particular the internal free end 73, is distant from the circulation field 12, in particular from the last dike 17 of the field 12 in the direction Y, as shown in FIG. 2. As better visible in FIG. 2, for each fin 71 B, it is advantageously provided that the external base end 72 is offset in the longitudinal direction X relative to the internal free end 73.

[0154] Preferably, each primary rim 13 is entirely flat, as is the case in the present example. Thus, the fins 71A and 71B as well as the seal 70 are arranged on the same flat area 13A of the primary rim 13, which extends along a plane perpendicular to the stacking direction Z. Alternatively, for the case where the primary rim 13 is not entirely flat, provision is still preferably made for the fins 71A and 71B to be arranged on the same flat area 13A, belonging to the reaction face 11. Preferably, the fins 20A and 20B protrude from the same flat area 13A. In particular, the seal 70 is not raised by a dam which would be formed by the rim 13, with respect to the fins 71A and 71B.

[0155] Preferably, the primary separator 10, at least for its circulation field 12 and its fins 20A and 20B, but also preferably for its openings 15 and 16, is symmetrical according to a 180° symmetry, relative to an axis of symmetry defined parallel to the stacking direction at the center of the primary separator 10. Preferably, the seal 70 and the fins 71A and 71B are also symmetrical according to the same symmetry.

[0156] As shown in Figures 3 to 5, the secondary separator 50 forms several secondary internal fins 60A and 60B. In other words, the secondary internal fins 60A and 60B are integral with the secondary separator 50. The fins 60A and 60B are therefore formed from the same material as the secondary separator 50, for example the same metallic material, and form a single piece in one piece with the secondary separator 50. In particular, it is provided that the fins 60A and 60B are obtained by the same process as that which made it possible to form the dikes 57 and the channels 58, namely, for example, a stamping of the sheet metal constituting the secondary separator 50, preferably during the same manufacturing step.

[0157] The fins 60A and 60B are intended to limit the quantity of secondary reactive fluid which bypasses the secondary circulation field 52 and which would circulate along the edges 53. The secondary internal fins 60A protrude, in relief in the opposite direction to the stacking direction Z, from one of the secondary edges 53, located in the transverse direction Y relative to the secondary circulation field 52. Preferably, in the longitudinal direction X, the fins 60A are regularly spaced along the secondary edge 53. The fins 60B protrude, in relief in the opposite direction to the stacking direction Z, from the other secondary edge 53, being regularly spaced along the longitudinal direction X. The same number of fins 60A is preferably provided as fins 60B.

[0158] Each secondary internal fin 60A and 60B comprises an internal base end 61 and an external free end 62, formed in relief in the opposite direction of the stacking direction Z relative to the secondary rim 53. For each fin 60A and 60B, the ends 61 and 62 are continuously connected, so that the fin 60A or 60B concerned is straight, or hook-shaped, or is bent from the end 61 to the end 62.

[0159] Each fin 60A and 60B is connected to the secondary circulation field 52 via its internal base end 61. In particular, for the fins 60A, the internal base end 61 is connected to the last dike 57 of the circulation field 52 in the direction Y. In particular, for the fins 60B, the internal base end 61 is connected to the last dike 57 of the circulation field 52, in the opposite direction to the direction Y.

[0160] Each fin 60A and 60B bears against the secondary gas diffusion layer 35 in the opposite direction to the stacking direction Z, at least for the internal base end 61.

[0161] For each fin 60A, the external free end 62 is arranged in the Y direction relative to the internal base end 61, so as to be as close as possible to the secondary peripheral seal 90. However, so that the peripheral seal 90 can be easily manufactured, in particular by overmolding, each secondary internal fin 60A, and in particular the external free end 62, is distant from the secondary peripheral seal 90, in particular in the transverse direction Y. The external free end 62 of the fin 60A extends beyond the central zone 36 in the transverse direction Y, and even preferably beyond the secondary gas diffusion layer 35. Thus, the external free end 62 of the fin 60A is arranged so as to be opposite the peripheral zone 37 opposite the secondary rim 53 on which this fin 60A is arranged. Preferably, the external free end 62 does not bear against the gas diffusion layer 35.For each fin 60A, it is advantageous to provide that the external free end 62 is offset in the longitudinal direction X relative to the internal base end 61.

[0162] For each fin 60B the internal base end 61 is arranged in the Y direction relative to the external free end 62, so that the external free end 62 is as close as possible to the secondary peripheral seal 90. Here also, so that the peripheral seal 90 can be easily manufactured, each secondary internal fin 60B is distant from the secondary peripheral seal 90, in particular in the transverse direction Y. The external free end 62 of the fin 60B extends beyond the central zone 36 in the opposite direction to the transverse direction Y, and even preferentially beyond the secondary gas diffusion layer 35. Thus, the external free end 62 of the fin 60B is arranged so as to be opposite the peripheral zone 37 opposite the secondary rim 53 on which this fin 60B is arranged.In the present example, the free end 62 is opposite the peripheral zone 37 with the interposition of the gas diffusion layer 35 between the peripheral zone 37 and the free end 62. Preferably, the external free end 62 is not in abutment against the gas diffusion layer 35. For each fin 60B, it is advantageous to provide that the internal base end 61 is offset in the longitudinal direction X relative to the external free end 62.

[0163] As shown in Figures 3 to 5, the cell 4 also comprises several secondary external fins 91 A and 91 B, which are integral with the peripheral seal 90. In other words, the secondary external fins 91 A and 91 B and the seal 90 form a single piece. The fins 91 A and 91 B are therefore formed from the same material as the secondary peripheral seal 90, for example an elastomer. In particular, it is provided that the fins 91 A and 91 B are obtained by the same process as that which made it possible to form the secondary peripheral seal 90, for example, overmolding on the face 51 of the secondary separator 50, preferably in the same manufacturing step.

[0164] The fins 91A and 91B are intended to limit the amount of secondary reactive fluid that bypasses the secondary circulation field 52 and that would circulate along the edges 53. The external fins 91A protrude, in relief in the opposite direction to the stacking direction Z, from one of the secondary edges 53, located in the transverse direction Y relative to the secondary circulation field 52. Along the longitudinal direction X, the fins 91A are regularly spaced along the edge 53. Along the direction X, each fin 91A is offset relative to one of the fins 60A that precedes or succeeds it. Preferably, the fins 91A are alternated with the fins 60A, as shown in FIG. 3. In other words, each fin 60A is immediately followed by a fin 91A and vice versa. This alternation of fins 60A and 91A makes it possible to effectively limit the quantity of reactive fluid which bypasses the circulation field 52, by forming baffles.Alternatively, a succession of a number N of fins 91A is provided, followed by the same number N of fins 60A, followed by the same number N of fins 91A and so on, where N is a natural number greater than or equal to two, such as two, three, four, five, or six. For example, when N = 2, there are two fins 91A followed by two fins 60A followed by two fins 91A. Alternatively, a succession of a number N1 of fins 91A is provided, followed by a different number N2 of fins 60A, followed by a number N1 of fins 91A and so on, where N1 and N2 are each a natural number greater than or equal to two, such as two, three, four, five, or six.

[0165] The secondary external fins 91 B project, in relief in the opposite direction to the stacking direction Z, from the other secondary rim 53, being regularly spaced along the longitudinal direction X, preferably also being alternated along the direction X with the fins 60B. The same number of fins 91 A as fins 91 B is preferably provided. The secondary external fins 91 A and 91 B project from their respective secondary rim 53 so as to be interposed, along the stacking direction Z, between the membrane-electrode assembly 30 and this secondary rim 53. In particular, for each fin 91 A and 91 B, a portion of the fin is interposed between the secondary gas diffusion layer 35 and this secondary rim 53.

[0166] Each secondary external fin 91 A and 91 B comprises an external base end 92, by means of which the fin 91 A or 91 B is connected to the secondary peripheral seal 90, and an internal free end 93, interposed between the secondary rim 53 carrying this fin 91 A or 91 B and the secondary gas diffusion layer 35. For each fin 91 A and 91 B, the ends 92 and 93 are continuously connected, so that the fin 91 A or 91 B concerned is straight, or hook-shaped, or is bent from the end 92 to the end 93.

[0167] It may be provided that the external base end 92 is opposite, in the stacking direction Z, the peripheral zone 37 of the membrane-electrode assembly 30, with a clearance between the external base end 92 and the peripheral zone 37 in the stacking direction Z. On the contrary, it may be provided that the end 92 is even in abutment against the peripheral zone 37.

[0168] For each fin 91A, the internal free end 93 bears against the secondary gas diffusion layer 35, extending at least in the excess thickness zone 47 in the opposite direction to the Y direction, or preferably extending in the excess thickness zone 42 or beyond the excess thickness zone 42 in the opposite direction to the Y direction. For each fin 91B, the internal free end 93 bears against the primary gas diffusion layer 35, extending at least in the excess thickness zone 47 in the Y direction, or preferably extending in the excess thickness zone 42 or beyond the excess thickness zone 42 in the Y direction. In other words, for each fin 91A, 91B, the internal free end 93 is arranged on the inside towards the secondary circulation field 52 relative to the excess thickness zone 42.

[0169] For each fin 91A the internal free end 93 is arranged in the opposite direction to the Y direction relative to the external base end 92, so as to be as close as possible to the circulation field 52. Nevertheless, so that the fin 91A can be easily manufactured, in particular by overmolding, each secondary external fin 91A, in particular the internal free end 93, is distant from the circulation field 52, in particular from the last dike 57 of the field 52 in the Y direction. As better seen in FIG. 3, for each fin 91A, it is advantageously provided that the external base end 92 is offset in the longitudinal direction X relative to the internal free end 93.

[0170] For each fin 91 B the internal free end 93 is arranged in the direction Y relative to the external base end 92, so as to be as close as possible to the circulation field 52. Nevertheless, so that the fin 91 B can be easily manufactured, in particular by overmolding, each secondary external fin 91 B, in particular the internal free end 93, is distant from the circulation field 52, in particular from the last dike 57 of the field 52 in the direction Y, as shown in FIG. 3. For each fin 91 B, it is advantageously provided that the internal free end 93 is offset in the longitudinal direction X relative to the external base end 92.

[0171] Preferably, each secondary rim 53 is entirely flat, as is the case in the present example. Thus, the fins 91A and 91B as well as the seal 90 are arranged on the same flat zone 53A of the secondary rim 53, which extends along a plane perpendicular to the stacking direction Z. Alternatively, for the case where the secondary rim 53 is not entirely flat, provision is still preferably made for the fins 91A and 91B to be arranged on the same flat zone 53A, belonging to the reaction face 51. In particular, the seal 90 is not raised by a dam which would be formed by the rim 53, with respect to the fins 91A and 91B. Preferably, the fins 60A and 60B protrude from the same flat zone 53A.

[0172] Preferably, the secondary separator 50, at least for its circulation field 52 and its fins 60A and 60B, but also preferably for its openings 55 and 56, is symmetrical according to a 180° symmetry, relative to an axis of symmetry defined parallel to the stacking direction at the center of the secondary separator 50. Preferably, the seal 90 and the fins 91A and 91B are also symmetrical according to the same symmetry.

[0173] Figure 6 shows an enlarged detail of the primary separator 10, shown in the same orientation as in Figure 2, including a portion of the seal 70, the last dam 17 and the fins 20A and 71A. Figure 6 further shows, in broken lines, as in transparency, the location of the excess thickness zone 42 belonging to the membrane-electrode assembly 30 belonging to the same cell 4, and which is superimposed along the stacking direction Z on the primary separator 10. Figure 6 further shows, in broken lines, as in transparency, the location of a portion of the seal 90, the last dam 57 and the fins 60A and 91A belonging to the secondary separator 50 of the same cell 4, superimposed on the membrane-electrode assembly 30 along the stacking direction Z.

[0174] Figures 4 to 6 show that each primary internal fin 20A and each secondary external fin 91A are preferably arranged so as to be aligned along the stacking direction Z, that is to say superimposed along the direction Z, for at least one intersection portion 29 of the fin 20A and one intersection portion 99 of the fin 91A. The intersection portions 29 and 99 are therefore superimposed along the stacking direction Z, being separated by the membrane-electrode assembly 30. In the example, the fact that the base ends 21 and 92 are offset in the longitudinal direction X relative to the free ends 22 and 93, the fins 20A and 91A are crossed, so that only the portions 29 and 99 are aligned along the stacking direction Z.As shown in Figure 6, it is advantageously provided that the excess thickness zone 42 and / or the excess thickness zone 47 is interposed between the intersection portions 29 and 99, along the stacking direction Z. This reduces the risks of deformation of the membrane-electrode assembly 30, in that the pressing of the fin 20A against the excess thickness zone 42 and / or 47 is compensated, in the opposite direction, by the pressing of the fin 91A against the excess thickness zone 42 and / or 47.

[0175] Likewise, preferably, each primary external fin 71A and each secondary internal fin 60A are preferentially arranged so as to be aligned along the stacking direction Z, that is to say superimposed along the direction Z, for at least one intersection portion 69 of the fin 60A and one intersection portion 79 of the fin 71A. The intersection portions 69 and 79 are therefore superimposed along the stacking direction Z, being separated by the membrane-electrode assembly 30. In the example, the fact that the free ends 73 and 62 are offset in the longitudinal direction X relative to the base ends 72 and 61, the fins 60A and 71A are crossed, so that only the portions 69 and 79 are aligned along the stacking direction Z. It is provided that the excess thickness zone 42 and / or the zone of excess thickness 47 is interposed between the intersection portions 69 and 79, following the stacking direction Z.Here too, this reduces the risk of deformation of the membrane-electrode assembly 30.

[0176] This arrangement of the fins 20A and 71A and of the fins 60A and 91A with respect to the zones of excess thickness 42 and / or 47 creates a local overcompression, to force any fluid flows, which usually tend to bypass the circulation field, to go around said fins, which imposes a pressure drop on these any fluid flows.

[0177] Concerning the alignment in the Z direction of the fins 20A and 91 A, that of the fins 60A and 71 A, and with the excess thickness zone 42 and / or 47, the same principles are applicable to the fins 20B and 91 B and to the fins 60B and 71 B.

[0178] Preferably, it is provided that all the cells 4 of the stack 2 are identical and that their various elements, in particular the fins, are aligned along the stacking direction Z.

[0179] Alternatively, instead of being stamped, the sheets forming the separators 10 and 50 are plastically deformed by another method. Alternatively, the separators 10 and 50 are formed from a machined, rather than plastically deformed, material, or are obtained from a plastically deformed and machined sheet.

[0180] As a further variant, the primary 10 and secondary 50 separators are manufactured by first providing a plate, already forming the primary 13 and end 14 flanges if it is a primary separator 10, or respectively, the secondary 53 and end 54 flanges, if it is a secondary separator 50. Then, an additive manufacturing step is applied to the plate to form both the primary circulation field 12 and the internal fins 20A, 30B, if it is a primary separator 10, or to form both the secondary circulation field 52 and the internal fins 60A, 60B, if it is a secondary separator 50.

[0181] Any feature described above for one embodiment or variant is applicable to other embodiments and variants, as far as technically possible.

Claims

CLAIMS 1.- Stack (2), for a fuel cell (1), the stack (2) defining a stacking direction (Z), a transverse direction (Y) and a longitudinal direction (X) distinct, and comprising: a primary separator (10), which extends perpendicular to the stacking direction (Z) and which comprises: • a primary circulation field (12), to guide a flow of primary reactive fluid (FH), and • a primary rim (13), which extends the primary separator (10) beyond the primary circulation field (12) in the transverse direction (Y); - a primary peripheral seal (70), which is interposed between the primary rim (13) and a peripheral zone (37) of a membrane electrode assembly (30), in the stacking direction (Z); and - at least one primary internal fin (20A), integral with the primary separator (10), which projects from the primary rim (13) in the stacking direction (Z), and which comprises: • an internal base end (21), connected to the primary circulation field (12) and intended to come into contact with a primary gas diffusion layer (34) of the membrane electrode assembly (30), in the stacking direction (Z), and • an external free end (22), which is intended to be opposite the peripheral zone (37) in the stacking direction (Z); characterized in that the stack (2) further comprises at least one primary external fin (71 A), which is integral with the primary peripheral seal (70), which projects, in relief in the stacking direction (Z), from the primary rim (13), said at least one primary internal fin (20A) and said at least one primary external fin (71 A) being offset from each other in the longitudinal direction (X), and said at least one primary external fin (71 A) comprising: - an external base end (72), connected to the primary peripheral seal (70); and - an internal free end (73), intended to be interposed between the primary rim (13) and the primary gas diffusion layer (34) in the stacking direction (Z). 2.- Stack (2) according to claim 1, in which the internal base end (21) of said at least one primary internal fin (20A) is offset in the direction longitudinal (X) relative to the external free end (22) of said at least one primary internal fin (20A). 3.- Stack (2) according to any one of the preceding claims, in which the internal free end (73) of said at least one primary external fin (71 A) is offset in the longitudinal direction (X) relative to the external base end (72) of said at least one primary external fin (71 A). 4.- Stack (2) according to any one of the preceding claims, in which several primary external fins (71 A) and several primary internal fins (20A) are provided and are distributed alternately along the primary rim (13). 5.- Stack (2) according to any one of the preceding claims, in which said at least one primary external fin (71 A) and the primary peripheral seal (70) are arranged on the same flat zone (13A) of the primary rim (13). 6.- Stack (2) according to any one of the preceding claims, in which said at least one primary internal fin (20A) is distant from the primary peripheral seal (70) in the transverse direction (Y). 7.- Stack (2) according to any one of the preceding claims, in which: - the primary circulation field (12) comprises dikes (17) and channels (18), which are distributed alternately along the transverse direction (Y); - each dike (17) and each channel (18) is generally oriented parallel to the longitudinal direction (X); - each channel (18) is bordered by two of the dikes (17) in the transverse direction (Y); each dike (17) is in relief in the stacking direction (Z) relative to the channel (18) which is bordered by said dike (17); - the dikes (17) comprise a last dike (17) which delimits the primary circulation field (12) and by means of which the primary rim (13), on which said at least one primary external fin (71 A) is arranged, is connected to the primary circulation field (12); and - the last dam (17) is distant from the internal free end (73) of said at least one primary external fin (71 A) in the transverse direction (Y). 8.- Stack (2) according to any one of the preceding claims, in which said at least one primary internal fin (20A), the primary rim (13) and the primary circulation field (12) are formed by the same plastically deformed sheet constituting the primary separator (10). 9.- Stack (2) according to any one of the preceding claims, in which: the stack (2) comprises the membrane electrode assembly (30), which extends perpendicular to the stacking direction (Z), which is superimposed with the primary separator (10), such that the membrane electrode assembly (30) is arranged in the stacking direction (Z) relative to the primary separator (10), the membrane electrode assembly comprising: • an exchange layer (33), which comprises a central zone (36) and the peripheral zone (37) which extends the exchange layer (33) beyond the central zone (36) in the transverse direction (Y), the exchange layer (33) comprising, at least in the central zone (36), a proton exchange polymer membrane (38), and • the primary gas diffusion layer (34), interposed, in the stacking direction (Z), between the primary circulation field (12) and the central zone (36); the internal base end (21) bears against the primary gas diffusion layer (34) in the stacking direction (Z); the internal free end (22) faces the peripheral zone (37) in the stacking direction (Z); - said at least one primary external fin (71 A) is interposed between the primary rim (13) and the membrane electrode assembly (30) in the stacking direction (Z); and - the internal free end (73) is interposed between the primary rim (13) and the primary gas diffusion layer (34) in the stacking direction (Z). Stack (2) according to claim 9, in which: - the stack (2) further comprises a secondary separator (50), which extends perpendicular to the stacking direction (Z), which is superimposed with the membrane-electrode assembly (30) so that the secondary separator (50) is arranged in the stacking direction (Z) relative to the membrane-electrode assembly (30), and which comprises: • a secondary circulation field (52), to guide a flow of secondary reactive fluid (FO), and • a secondary rim (53), which extends the secondary separator (50) beyond the secondary circulation field (52) in the transverse direction (Y); - the membrane-electrode assembly (30) comprises a secondary gas diffusion layer (35), interposed, in the stacking direction (Z), between the central zone (36) and the secondary circulation field (52); - the stack (2) further comprises a secondary peripheral seal (90), which is interposed between the peripheral zone (37) and the secondary rim (53) in the stacking direction (Z); - the stack (2) further comprises at least one secondary external fin (91 A), which is integral with the secondary peripheral seal (90), which is interposed between the membrane-electrode assembly (30) and the secondary rim (53) in the stacking direction (Z), and which comprises: • an external base end (92), connected to the secondary peripheral seal (90), and • an internal free end (93), interposed between the secondary gas diffusion layer (35) and the secondary rim (53) in the stacking direction (Z). Stack (2) according to claim 10, in which the external base end (92) of said at least one secondary external fin (91 A) is offset in the longitudinal direction (X) relative to the internal free end (93) of said at least one secondary external fin (91 A). Stack (2) according to any one of claims 10 or 11, wherein said at least one primary internal fin (20A) and said at least one secondary external fin (91 A) are arranged in an aligned manner in the stacking direction (Z), at least for a respective intersection portion (29, 99) of said at least one primary internal fin (20A) and said at least one secondary external fin (91 A).Stack (2) according to claim 12, in which: the peripheral zone (37) of the exchange layer (33) is formed by a holding frame (39) which has an internal peripheral portion (40) delimiting the central zone (36) occupied by the proton exchange polymer membrane (38), the holding frame (39) being assembled by the internal peripheral portion (40) to an external peripheral portion (41) of the proton exchange polymer membrane (38); - the primary gas diffusion layer (34), the holding frame (39) and the secondary gas diffusion layer (35) form an excess thickness zone (42, 47), where the primary gas diffusion layer (34), the holding frame (39) and the secondary gas diffusion layer (35) are superimposed in the stacking direction (Z); - the primary gas diffusion layer (34), the proton exchange polymer membrane (38) and the secondary gas diffusion layer (35) form a zone of lesser thickness (46), where the primary gas diffusion layer (34), the proton exchange polymer membrane (38) and the secondary gas diffusion layer (35) are superimposed along the stacking direction (Z); along the stacking direction (Z), a thickness of the membrane-electrode assembly (30), measured in the excess thickness zone (42), is greater than a thickness of the membrane-electrode assembly (30) measured in the lesser thickness zone (46); and the excess thickness zone (42, 47) is interposed, along the stacking direction (Z), between the intersection portion (29) of said at least one primary internal fin (20A) and the intersection portion (99) of said at least one secondary external fin (91 A). Fuel cell (1) comprising the stack (2) according to any one of the preceding claims.

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