Alignment device for a cell stack, particularly a fuel cell stack

Abstract

A battery stack (1) comprising at least a plurality of electrical plates (2) and a plurality of insulating layers (18), the stack of the plurality of electrical plates (2) and insulating layers (18) being stacked alternately such that the electrical plates (2) are separated by the insulating layers (18) and the electrical plates (2) and / or insulating layers (18) are aligned with one another, each electrical plate (2) having a first alignment through hole (14) and a second alignment through hole (16), and the electrical plates (2) and / or insulating layers (18) are aligned with one another, the electrical plates (2) having a first alignment through hole (14) and a second alignment through hole (16) and the electrical plates (2) and / or insulating layers (18) being aligned with one another, the electrical plates (2) and / or insulating layers (18) being stacked alternately such that the electrical plates (2) and / or insulating layers (18) are aligned with one another, the electrical plates (2) having a first alignment through hole (14) and a second alignment through hole (16) and the electrical plates (2) and / or insulating layers (18) are aligned with one another, the electrical plates (2) and / or insulating layers (18) being stacked alternately such that the electrical plates (2) and / or insulating layers (18) are aligned with one another, the electrical plates (2) and / or insulating layers (18) being stacked alternately ... and / or a battery stack (1) is disclosed in which internal alignment elements (30) are provided for aligning the electrical plates (2) and the insulating layer (18), each internal alignment element (30) having a base plate (32) and an alignment portion (34) protruding from the base plate (32), and the alignment portion (34) of one alignment element (30) extends through at least the first electrical plate (2), the first insulating layer (18), the second electrical plate (2) and the second insulating layer (18).

Description

[Technical field]

[0001] The present invention relates to a cell stack, in particular a fuel cell stack, according to claim 1. [Background technology]

[0002] A cell stack typically consists of multiple stacked electrical plates separated from each other by insulating layers.

[0003] In the special case of a fuel cell stack, the electrical plates are bipolar plates and the insulating layers are multi-layer membrane electrode assemblies. The bipolar plates themselves are a combination of anode and cathode plates fixed to each other, which are separated, or in other words sandwiched, by the membrane electrode assembly. The cathode and anode plates forming the bipolar plates are usually conductive metal or graphite plates, so-called flow field plates, which have flow fields for reactants on one side and for cooling fluids on the other side. In the assembled membrane electrode assembly, the flow field plates are placed on top of each other with the cooling fluid flow fields facing each other and the reactant flow fields facing the sandwiching membrane electrode assembly. The currents generated by the membrane electrode assembly during the operation of the fuel cell stack will result in a potential difference between the bipolar plate assemblies.

[0004] To form a battery stack, all the electrical plates and insulating layers, e.g., membrane electrode assemblies and bipolar plates, are stacked alternately on top of each other. However, the alignment of each electrical plate to its associated insulating layer, e.g., membrane electrode assembly, is critical to the performance of the completed battery stack, as is the alignment between the electrical plates themselves.

[0005] The desired alignment is typically achieved using an alignment mechanism, such as an alignment rod or an alignment rack, which interacts with alignment structures on the electrical plates. However, after aligning the stack, the stack must be removed from the alignment mechanism, with the risk of losing the alignment of the electrical plates and the insulating layers. Summary of the Invention [Problem to be solved by the invention]

[0006] It is therefore an object of the present invention to provide a cell stack in general, and a fuel cell stack in particular, that allows for a more efficient stack and more reliable alignment of the stacked components without the risk of loosening the alignment when the stack is removed from the alignment mechanism. [Means for solving the problem]

[0007] This object is solved by a battery stack according to claim 1.

[0008] Below, a cell stack, in particular a fuel cell stack, is proposed, which consists of at least a number of electrical plates and a number of insulating layers, whereby the electrical plates and the insulating layers are stacked such that the electrical plates are separated by insulating layers and the electrical plates and / or the insulating layers are aligned with each other.

[0009] Generally, in this application, the term "electrical plate" does not necessarily refer to a rigid electrical plate. Similarly, an electrical element (anode or cathode), such as a flexible layer, may be termed an electrical plate in this application.

[0010] However, when the cell stack is a fuel cell stack, the electrical plates are bipolar plates, each consisting of an anode plate and a cathode plate fixed together, and the insulating layer is then a multi-layer membrane electrode assembly. The bipolar plates are typically rigid metal or graphite plates with flow field mechanisms for supplying and distributing reactants and / or coolants to the bipolar plates and / or the adjacent membrane electrode assemblies.

[0011] To ensure automatic alignment of the electrical plates with respect to one another, each electrical plate has a first alignment through-hole and a second alignment through-hole on which and / or within which internal alignment elements are provided for aligning the electrical plates and the insulating layers, and these internal alignment elements ensure that the stacked components remain in a stacked and aligned position even when external stacking or alignment devices, such as alignment rods or alignment racks, are removed.

[0012] To that end, the first and second alignment through holes may preferably be separated from each other diagonally or diametrically with respect to the electrical plate.

[0013] It should further be noted that the insulating layer may be provided with corresponding alignment through holes and may cooperate with the alignment elements as well. It should further be noted that the alignment elements may also be an integral part of the insulating layer. In the case of a fuel cell, the insulating layer is a membrane electrode assembly and the alignment elements are preferably an integral part of a subgasket of the membrane electrode assembly.

[0014] Further, each internal alignment element has a base plate and an adjustment portion protruding from the base plate, the adjustment portion of an alignment element extending through at least the first electrical plate, the first insulating layer, the second electrical plate, and the second insulating layer, and when the alignment element is an integral part of the insulating layer, the base plate may be flush with the insulating layer.

[0015] The internal alignment elements extend through at least two unit cells (each unit cell consisting of one electrical plate and one insulating layer) to ensure that the adjacent electrical plates are aligned with each other. Furthermore, as mentioned above, the internal alignment elements allow for permanent alignment throughout the life of the cells, not just during the stack.

[0016] According to a further preferred embodiment, the adjustment portion of the alignment element is recessed from the base plate, so that a step is formed between the base plate and the adjustment portion, which allows for easy attachment of the alignment element to the electrical plate. Alternatively, the alignment element can also be attached by other fastening methods, for example by click-fitting the alignment element to the electrical plate, by welding / soldering the alignment element to the electrical plate, or by integrating the alignment element between the anode and cathode plates of a bipolar plate.

[0017] To improve the accuracy and precision of the alignment, it is further preferred if, on the opposite side of the adjustment portion, the base plate of the alignment element has a recess dimensioned to accommodate the adjustment portion of a second adjacent alignment element, so that a first alignment element is configured to be stacked on top of a second alignment element. The cooperation between the recess of the base plate of one alignment element and the adjustment portion of the adjacent alignment element allows the formation of an internal alignment rod that fixes the orientation of the stacked components relative to one another. Furthermore, this allows for space-efficient stacking of the alignment elements, as they can be stacked on top of one another.

[0018] Thereby, it is particularly preferred if the alignment elements are arranged such that for each single electric plate, one of the alignment through-holes is in contact with the base plate of a first alignment element, and the other alignment through-hole of the very same electric plate is only in contact with the adjustment portion of another second alignment element. Thereby, the alignment elements are arranged alternately and extend through the second electric plates oriented by the preceding alignment element. That is, for example, on electric plate 1, the base plate of the first alignment element 1 is arranged and its adjustment portion extends through electric plate 2, on electric plate 2, the base plate of the second alignment element is arranged and its adjustment portion extends through electric plate 3, on electric plate 3, the base plate of the third alignment element is arranged and its adjustment portion extends through electric plate 4, etc. In this way, all electric plates are interconnected by alignment elements, which improves the stack and alignment accuracy.

[0019] In order to simplify the above-mentioned interleaving of alignment elements on / in the alignment through-holes, it is further preferred that the first alignment through-hole has a first shape and the second alignment through-hole has a second shape, the first and second shapes being different. In that regard, it is particularly preferred if one of the alignment through-holes has an elongated shape, whereas the second alignment through-hole has a circular shape. Additionally or alternatively, the first alignment through-hole is arranged at a different position than the second alignment through-hole. This allows a reliable and automatic alignment of the electrical plate and the insulating layer.

[0020] Furthermore, it is preferred if the shape of the base plate of the internal alignment element and / or the shape of the adjustment portion of the alignment element matches the shape / dimension of the alignment through-holes of the electrical plate, thereby allowing fail-safe stacking and alignment of components and improving stacking and alignment accuracy.

[0021] In that regard, it is further preferred if the size and shape of the alignment through holes are slightly larger than the size and shape of the alignment elements, so that there is a clearance fit between the alignment elements and the alignment through holes in the stack, pre-aligning the components, and final alignment is achieved by subsequent compression of the stack while the alignment elements are deformable within the remaining space of the alignment through holes, so that after compression of the stack, internal alignment elements fit snugly into the alignment through holes, providing long-life alignment of the stack.

[0022] According to a further preferred embodiment, adjacent electrical plates and the corresponding first and second alignment through-holes are arranged such that the first alignment through-hole of one electrical plate is aligned with the second alignment through-hole of the adjacent electrical plate. In that regard, it is preferred if the electrical plates are symmetrical with respect to a rotation of 180° about the surface normal of the electrical plates. In case the electrical plates are bipolar plates, it is preferred that the bipolar plates are symmetrical with respect to a rotation of 180° about the surface normal of the cathode or anode side. Thereby, a rotation of 180° of each second electrical plate of the stack results in an automatic alternating arrangement of the first and second alignment through-holes. Besides the simplification of manufacturing, stacking and alignment, the fact that only one set of electrical plates needs to be produced also allows for the compensation of manufacturing tolerances that may lead to stacks of unequal dimensions.

[0023] As mentioned above, the at least one insulating layer may further comprise an alignment through-hole configured to cooperate with at least one alignment element. Preferably, the insulating layer may have two alignment through-holes arranged corresponding to the first and second alignment through-holes of the electrical plate. However, it is also possible that the alignment through-holes of the insulating layer have different dimensions and / or shapes than the first and second alignment through-holes of the electrical plate.

[0024] As noted above, each alignment element extends through at least the first electrical plate, the first insulating layer, the second electrical plate, and the second insulating layer. Thus, the total height h of the alignment element is a is equal to or greater than two cell pitches (one cell pitch is the total height of the electrical plate and the insulating layer): H ≥ 2 × (D EP +D IL For a fuel cell stack, this relationship is H ≥ 2 × (D BBP +D MEAThat is, the alignment element is preferably higher than two cell pitches such that the top of the alignment element extends to the second unit battery.

[0025] According to a further preferred embodiment, the adjustment portion of each alignment element has a first adjustment portion and a second adjustment portion, the size and / or shape of the first adjustment portion matching the shape of the first alignment through-hole and / or the size and / or shape of the second adjustment portion matching the shape of the second alignment through-hole, which further enables fail-safe alignment and stacking of components.

[0026] In that regard, it is particularly advantageous if the second adjustment portion of the adjustment portion of the alignment element is recessed from the first adjustment portion, thereby forming a step between the first and second adjustment portions of the alignment element, preferably with the dimensions of the first adjustment portion adapted to the dimensions and / or shape of the first alignment through-hole and the dimensions of the second adjustment portion adapted to the dimensions and / or shape of the second alignment through-hole, which allows for alignment through-holes of various sizes and shapes and improves stacking accuracy.

[0027] According to a further preferred embodiment, the height h of the first adjustment part a1 is one cell pitch, i.e., the thickness D of the electrical plate EP + the thickness D of the insulating layer IL (h a1 ≒D EP +D IL ) while the height h a2 is one cell pitch or more (h a2 ≧D EP +D IL For fuel cells, this relationship is expressed as h a2 ≧D BBP +D MEA This shows that:

[0028] Furthermore, the recess h of the base plater and the shape and height h a2 The excess part of the adjustment part that exceeds the height of one cell pitch is the depth h of the recess. r may be designed to fit: a2 ≒D EP +D IL +h r For fuel cells, this relationship is h a2 ≒D BPP +D MEA +h r This may allow the alignment elements to be stacked on top of each other.

[0029] It should be noted that the relationships specified above take into account compression of the completed stack.

[0030] It is also possible to configure the alignment portion of the alignment element to be larger than a multiple (two or more) cell pitch such that the alignment element is configured to align with multiple unit cells, rather than just connecting two adjacent electrical plates and their corresponding insulating layers. This has the added advantage that the number of alignment elements can be reduced, since each alignment element can align with multiple unit cells. Also, the number of alignment elements required can be reduced.

[0031] According to a further preferred embodiment, the electrical plate further comprises a flow field for distributing reactants on the electrical plate. In that regard, the flow field may be formed as a protruding structure protruding from the base of the plate. Alternatively, the plate may have other protruding structures, e.g. bead seals, also protruding from the base of the electrical plate. These protruding structures are common in fuel cells, where the bipolar plate is designed to distribute reactants to the membrane electrode assembly.

[0032] When the electrical plate has at least one protruding structure, e.g., a bead seal or a flow field, protruding from the base of the electrical plate in the direction of the adjacent insulating layer, the height h of the base plate of the alignment element b is the protruding height D of the protruding structure above the base of the electrical plate PS (h b ≒D PS , preferably h b <D PS ) is even more preferable.

[0033] According to a further preferred embodiment, when the electrical plate has at least one protruding structure, not only the height of the base plate of the alignment element but also the first adjustment part of the adjustment part may be close to the height of the protruding structure (h a1 <D PS This embodiment allows for an insulating layer having alignment through holes that are identically shaped and match the size and shape of the second adjustment portion of the adjustment part, allowing for a freely positionable insulating layer.

[0034] According to a further preferred embodiment, due to the potential difference between the electric plates, it is preferred if the alignment elements are made from an electrically insulating material, for example a plastic material. It is further advantageous if the alignment elements are moulded, preferably injection moulded.

[0035] Further preferred embodiments are defined in the description and drawings, as well as in the dependent claims, whereby an element described or shown in combination with other elements may also be present alone or in combination with other elements, without departing from the scope of protection.

[0036] In the following, preferred embodiments of the invention are described with reference to the drawings, which are for illustrative purposes and not for limiting the scope of protection, which is defined only by the appended claims. [Brief description of the drawings]

[0037] [Figure 1] FIG. 2 is a schematic plan view of a bipolar plate of the fuel cell stack according to the first embodiment. [Diagram 2] FIG. 2 is a schematic plan view of a membrane electrode assembly of a fuel cell stack according to a first embodiment. [Diagram 3] 1 is a schematic cross-sectional view through part of a fuel cell stack according to a first embodiment; [Figure 3a] 1 is a schematic cross-sectional view through part of a fuel cell stack according to a first embodiment; [Figure 4] FIG. 5 is a schematic cross-sectional view through part of a fuel cell stack according to a second embodiment. [Diagram 5] FIG. 4 is a schematic enlarged cross-sectional view through the alignment element shown in FIG. 3. [Figure 6] FIG. 5 is a schematic enlarged cross-sectional view through the alignment element shown in FIG. 4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] In the following, elements that function identically or similarly are designated with the same reference numbers.

[0039] Below, the principles of the invention are described in the context of a fuel cell stack, but the principles are equally applicable to any other type of cell or cell stack.

[0040] FIG. 1 shows a simplified schematic plan view of a bipolar plate 2 (electrical plate) of a fuel cell stack 1 according to a first embodiment. Typically, each bipolar plate 2 is a combination of an anode plate and a cathode plate fixed to each other. Each anode and cathode plate has a front side and a back side, with the front or reactant side facing the adjacent membrane electrode assembly (not shown in FIG. 1) and the back or coolant side facing each other. Furthermore, each bipolar plate 2 has a number of openings 4, 6, i.e. manifolds, for supplying (openings 4) and draining (openings 6) reactants and coolant to / from the bipolar plate 2. To distribute the reactants and coolant over the plate, the bipolar plate may further have protruding structures (not shown), forming fluid flow fields 8 for the respective reactants / coolant. To seal the flow fields against the environment, the plate further comprises so-called bead seals 10, which protrude from the base 12 of the plate and may extend beyond the height of the flow field structures.

[0041] Furthermore, the bipolar plate 2 has a first alignment through hole 14 and a second alignment through hole 16, with the first alignment through hole 14 being located at a different position than the second alignment through hole 16. In Figure 1, the first alignment through hole 14 is located diametrically opposite the second alignment through hole 16. This makes the first and second alignment through holes 14, 16 symmetrical with respect to a 180° rotation about the surface normal of the bipolar plate.

[0042] 1, the first alignment through hole 14 has an elongated shape, while the second alignment through hole 16 has a circular shape. Thus, the alignment through holes have different shapes and dimensions. However, it would be possible for the first and second alignment through holes 14;16 to both have elongated shapes, in which case the longitudinal axis of the first alignment through hole 14 may be perpendicular to the longitudinal axis of the second alignment through hole 16.

[0043] FIG. 2 shows a membrane electrode assembly 18 that can be used in combination with the bipolar plate of FIG. 1 in a fuel cell stack. As can be seen in FIG. 2, the membrane electrode assembly 18 further includes alignment through-holes 20, 22 that allow alignment of the bipolar plate 2 with the membrane electrode assembly 18. As can be seen from a comparison of FIG. 1 and FIG. 2, the membrane electrode assembly 18 may have the same or similar shape as the bipolar plate 2, and has an active area 24 that is in the same area as the flow field area of ​​the bipolar plate 2. The active area 24 of the membrane electrode assembly 18 is typically a three-layer membrane electrode assembly consisting of a membrane sandwiched between an anode and a cathode. Other structures such as manifold openings 26 or alignment through-holes 20, 22 are preferably provided in a subgasket material 28 that surrounds and supports the active area 24 of the three-layer membrane electrode assembly and electrically insulates the sandwiching bipolar plates. Additionally, the membrane electrode assembly may further comprise gas diffusion layers (not shown) on both sides, also disposed within the active area 24 and covering the anode and cathode of the three-layer membrane electrode assembly 18 .

[0044] Figures 3 and 4 and their enlarged views 3a and 4a respectively show schematic cross-sectional views along line II-II in Figure 1 through alignment through-holes 14; 16 of two embodiments of a fuel cell stack 1 consisting of a number of bipolar plates 2-1, 2-2, 2-3, 2-4 and interlayer membrane electrode assemblies 18-1, 18-2, 18-3, 18-4. For simplicity, in the cross-sectional views of Figures 3 and 4, the bipolar plates 2 are shown with a height D PS 1 is shown diagrammatically as a single plate with a protruding structure 10 protruding above a base 12 by just a small amount.

[0045] 3 and 4 shows a special stacking order of the bipolar plates and membrane electrode assemblies, in which all the second bipolar plates 2-2, 2-4... are rotated 180° with respect to the bipolar plates 2-1, 2-3..., so that the first alignment through-holes 14-1, 14-3... of the first bipolar plates 2-1, 2-3... are aligned with the second alignment through-holes 16-2, 16-4... of the second bipolar plates 2-2, 2-4.... The same will apply to the membrane electrode assemblies 18.

[0046] The bipolar plate 2 and the multilayer membrane electrode assembly 18 are aligned with each other by a number of alignment elements 30. Figures 5 and 6 show an enlarged view of the alignment element 30 according to the embodiment shown in Figure 3 (Figure 5), and in Figure 6 an enlarged view of the alignment element 30 according to the second embodiment of Figure 4 is shown.

[0047] Due to the potential difference between the bipolar plates 2, the alignment element 30 is made from a molded, preferably injection molded, electrically insulating material, such as a plastic material. In a particular embodiment not shown, the alignment element 30 may be an integral part of the multi-layer membrane electrode assembly 18, preferably the subgasket 28.

[0048] 5 and 6, alignment element 30 has a base plate 32 and an adjustment portion 34 that is recessed from base plate 32 such that a step 33 is formed between base plate 32 and adjustment portion 34. Thus, base plate 34 has a height h b The adjustment part has a total height h a has.

[0049] The adjustment portion 34 further comprises a first adjustment portion 36 and a second adjustment portion 38, the second adjustment portion 38 being recessed relative to the first adjustment portion 36 to form a further step 37 between the first and second adjustment portions 36, 38 of the adjustment portion 34. In that regard, the first adjustment portion 36 has a height h a1and the second adjustment portion 38 has a height h a2 has.

[0050] Opposite the adjustment portion 34, the base plate 32 of the alignment element 30 has a recess 39. The recess 39 has a dimension and a depth h r are selected such that the adjustment portions 34, and in particular the adjustment portions 38, of adjacent alignment elements 30 can be received in the recesses 39, thereby allowing the alignment elements 30 to be stacked on top of one another, as will be described in further detail below.

[0051] 3 and 4, the height of the base plate 32 is preferably less than the thickness D of the protruding structures 10 of the bipolar plate 2, e.g., the bead seal. PS It is designed to be close to: b ≒D PS , preferably h b ≦D PS This allows for the placement of the internal alignment elements 30 in the bipolar plate 3 without the additional space requirement of the alignment elements 30. Preferably, the dimensions or height of the base plate 32 are less than the height h of the base plate 32 even after compression of the stack. b is still less than the height of the protruding structures 10. This ensures that all height relationships discussed in this application still apply after the stack is compressed.

[0052] As can be seen from Figures 3 and 4, the total height H of the alignment element is at least two cell pitches d = D MEA +D BPP The cell pitch is defined as the distance between two unit fuel cells, and each unit fuel cell is composed of a bipolar plate 2 and a membrane electrode assembly 18: H≧2×(D MEA +D BPP ).

[0053] In the illustrated embodiments of FIGS. 3 and 5 and 4 and 6, respectively, the height h of the adjustment portion 34 a1 ,h a2In the embodiment shown in FIG. 5 and FIG. 3, the height h of the first adjustment portion 36 is different from that of the first adjustment portion 36. a1 is close to one cell pitch (h a1 ≒D BPP +D MEA ) whereas the height h of the second adjustment portion 38 a2 is larger than one cell pitch (h a2 ≧D BPP +D MEA In this embodiment, the membrane electrode assembly 18 further preferably includes first and second alignment through-holes 20, 22 that are different in size and shape.

[0054] In another preferred embodiment shown in FIG. 6 and FIG. 4, the height h a1 is less than the height of the protruding structure (h a1 ≦D PS ) whereas the height h of the second adjustment portion 38 a2 is greater than the cell pitch plus the height of the membrane electrode assembly (h a2 ≧D BPP +2×D MEA ). This allows for a fuel cell stack 1 where the bipolar plate 2 only needs to include first and second alignment through-holes 14, 16. The membrane electrode assembly 18 may include alignment through-holes 20, 22 of equal size.

[0055] As can be seen from Figures 3 and 4, the dimensions of the first adjustment portion 36 may be close to the dimensions of the first alignment through-hole 14 of the bipolar plate 2, and the dimensions of the second adjustment portion 38 may be close to the dimensions of the second alignment through-hole 16 of the bipolar plate 2. With regard to the membrane electrode assembly 18, the situation is different from that shown for example in Figure 3, and similarly to the bipolar plate 2, the dimensions of the first adjustment portion 36 may be close to the dimensions of the first alignment through-hole 20 of the membrane electrode assembly 18, and the dimensions of the second adjustment portion 38 may be close to the dimensions of the second alignment through-hole 22 of the membrane electrode assembly 18. In the embodiment of Figure 4, in contrast, the dimensions of both alignment through-holes 20 and 22 of the membrane electrode assembly 18 may both be close to the dimensions of the second adjustment portion 38.

[0056] 3 and 4, the alignment elements are arranged alternately on the bipolar plate 2. That is, in the bipolar plate 2-1, the first alignment element 30-1 is arranged in the first alignment through-hole 14-1 of the first bipolar plate 2-1 so that the base plate 32 contacts the first bipolar plate 2-1 and the first adjustment portion 36-1 of the first alignment element 30-1 extends through the first alignment through-hole 14-1. Then, in the second alignment through-hole 16-1 of the first bipolar plate 2-1, the second alignment element 30-2 is arranged such that its second adjustment portion 38-2 extends through the second alignment through-hole 16-1 of the first bipolar plate 2-1.

[0057] In the adjacent bipolar plate 2-2, the situation is the same, but the bipolar plate 2-2 is rotated by 180°, so that the alignment through-holes 14-2, 16-2 are reversed. Thus, the second adjustment part 38-1 of the first alignment element 30-1 extends through the corresponding second alignment through-hole 16-2 of the second bipolar plate 2-2, whereas in the first alignment through-hole 14-2 of the second bipolar plate 2-2, the base plate 32-3 of the third alignment element 30-3 is placed, whose first adjustment part 36-3 extends through the first alignment through-hole 14-2 of the second bipolar plate 2-2.

[0058] For the third bipolar plate 2-3, or generally the n+1th bipolar plate of the stack, the situation is the same as for the first bipolar plate, and for the fourth bipolar plate 2-4, or generally the 2nth bipolar plate, the situation is the same as for the second bipolar plate 2-2.

[0059] As mentioned above and shown in the enlarged views of FIGS. 3a and 4a, the total height h of the adjustment portion 34 of the alignment element 30 ais configured to be larger than two cell pitches d. That is, the adjustment portion 34-1 of the first alignment element 30 extends through the second alignment through-hole 16-2 and the second membrane electrode assembly 18-2 of the second bipolar plate 2-2, and protrudes onto the second membrane electrode assembly 18-2 and into the space formed by the protruding structure 10-3 of the third bipolar plate 2-3. This design allows the stacking of the alignment elements 30-1 and 30-3, since the part of the adjustment portion 38 that extends into the space of the third bipolar plate can be accommodated in the recess 39-2 of the adjacent alignment element 30-2.

[0060] Therefore, the recess 39 of the first alignment element 30-1 and the second adjustment portion 38-1 of the first alignment element 30-1 are preferably designed so that the second adjustment portion 38 of the second alignment element 30-2 can be accommodated in the recess 29 of the first alignment element 30-1. r is a part of the adjustment portion 38 extending into the space of the third bipolar plate, the recess depth h r It is designed to fit.

[0061] To compensate for the loss in height when the stack is compressed after stacking, the alignment through holes and alignment elements may be designed such that only a clearance fit is formed between the adjustment portions 36, 38 and the corresponding alignment through holes 14, 16 during stacking. When the stack is compressed, the alignment elements may deform to fill the remaining space. Alternatively or additionally, the recesses 39 in the base plate 22 may be made deeper than necessary to accommodate the additional height of the alignment elements during compression.

[0062] In summary, by providing alignment through-holes cooperating with each alignment element, it is possible to provide a fuel cell stack that allows for a more efficient stack and more reliable alignment of the stacked components without the risk of loosening the alignment when the stack is removed from the alignment mechanism. At the same time, the cooperating alignment through-holes and alignment elements allow for balancing manufacturing tolerances in plate thickness. [Explanation of symbols]

[0063] 1. Fuel cell stack 2 Bipolar Plates 4,6 Reactant / coolant manifold 8 Flow field section 10 Protruding elements 12 Bipolar plate base 14 First alignment through hole (bipolar plate) 16 Second alignment through hole (bipolar plate) 18 Membrane Electrode Assembly 20 First alignment through hole (membrane electrode assembly) 22 Second alignment through hole (membrane electrode assembly) 24 Active Area 26 Manifold opening 28 Subgasket 30 Alignment Elements 32 Base plate 34 Adjustment part 33 Step between base plate and adjustment part 36 1st adjustment section 38 Second adjustment section 37 Step between the first and second adjustment parts 39 Recess H Overall height of alignment element h b Base plate height h a Height of adjustment part h a1 Height of the first adjustment part ha2 Second adjustment part height D MEA Membrane electrode assembly thickness D BPP Bipolar Plate Thickness D PS Bipolar plate protruding part thickness d Cell pitch

Claims

1. A battery stack (1) consisting of at least a plurality of electrical plates (2) and a plurality of insulating layers (18), the stack of the plurality of electrical plates (2) and insulating layers (18) being stacked alternately such that the electrical plates (2) are separated by insulating layers (18) and the electrical plates (2) and / or the insulating layers (18) are aligned with each other, Each electrical plate (2) has a first alignment through hole (14) and a second alignment through hole (16), and an internal alignment element (30) is provided on and / or within said alignment through holes (14; 16) for aligning said electrical plate (2) and said insulating layer (18), and each internal alignment element (30) has a base plate (32) and an adjustment portion (34) protruding from said base plate (32), and said adjustment portion (34) of one alignment element (30) extends through at least the first electrical plate (2), the first insulating layer (18), the second electrical plate (2) and the second insulating layer (18) such that a total height H of said alignment element is equal to or greater than two cell pitches (H≧2×(D ＥＰ +D ＩＬ ), the adjustment portion (34) of each alignment element (30) has a first adjustment portion (36) and a second adjustment portion (38), the dimensions and / or shape of the first adjustment portion (36) matching the dimensions and / or shape of the first alignment through hole (14), and / or the dimensions and / or shape of the second adjustment portion (38) matching the dimensions and / or shape of the second alignment through hole (16).

2. 2. The battery stack (1) of claim 1, wherein the first alignment through holes (14; 16) have a first shape, preferably an elongated shape, and the second alignment through holes (14; 16) have a second shape, preferably a circular shape, and the first and second shapes are different.

3. 3. The battery stack (1) of claim 1 or 2, wherein the adjustment portion (34) of the alignment element (30) is recessed from the base plate (32) such that a step (33) is formed between the base plate (32) and the adjustment portion (34).

4. 4. A battery stack (1) according to any one of claims 1 to 3, wherein the base plate (32) of the alignment element (30) has a recess (39) on an opposite side to the adjustment portion (34) that is dimensioned to receive the adjustment portion (34) of an adjacent second alignment element (30), thereby configuring one alignment element (30-1) to be stacked on a further alignment element (30-3).

5. 5. A battery stack (1) as claimed in any one of claims 1 to 4, wherein the second adjustment portion (38) is recessed from the first adjustment portion (36) to form a step (37) between the first and second adjustment portions (36; 38) of the alignment element (30).

6. The height h of the first adjustment portion (36) of the adjustment portion (34) ａ１ corresponds to at least one cell pitch, i.e., the thickness of one electrical plate (2) plus one insulating layer (18), or an integer multiple of the cell pitch (h ａ１ = x × (D ＥＰ +D ＩＬ ) (x is an integer)), and the height h of the second adjustment portion (38) of the adjustment portion (34) is ａ２ is at least one cell pitch, or an integer multiple of the cell pitch, i.e., the thickness of one electrical plate (2) and one insulating layer (18) (h ａ２ ≧x×(D ＥＰ +D ＩＬ 6. The battery stack (1) according to claim 1, wherein x is an integer.

7. The height h of the second adjustment portion (38) of the adjustment portion (34) ａ２ is at least one cell pitch or an integer multiple of the cell pitch (h ａ２ >x x (D ＥＰ +D ＩＬ ) (x is an integer) so that the second adjustment portion exceeds the height of one cell pitch or an integer multiple of the cell pitch by an excess portion, and on the opposite side of the adjustment portion (34), the base plate (32) of the alignment element (30) has a recess (39) dimensioned to receive the excess portion of the second adjustment portion (38) of the adjustment portion (34) of an adjacent second alignment element (30) such that one alignment element (30-1) is configured to be stacked on a further alignment element (30-3), and the depth of the recess is configured to receive the excess portion of the second adjustment portion (38) of the adjustment portion (34), so that ａ２ ≒ x × (D ＥＰ +D ＩＬ ) + h ｒ The battery stack (1) according to claim 6,

8. 8. A battery stack (1) according to any one of claims 1 to 7, wherein the alignment elements (30) are arranged such that, for each single electrical plate (2), one of the alignment through holes (14; 16) contacts the base plate (32) of a first alignment element (30-1) and the other alignment through hole (14; 16) of the very same electrical plate (2) contacts the adjustment portion (34-2) of another second alignment element (30-2).

9. 9. A battery stack (1) according to any one of claims 2 to 8, wherein the base plate (32) of the internal alignment element (30) is disposed on / in the first alignment through-hole (14; 16) having the first shape.

10. 10. A battery stack (1) according to any one of claims 1 to 9, wherein adjacent electrical plates (2) and corresponding first and second alignment through holes (14; 16) are arranged such that the first alignment through hole (14) of one electrical plate (2) is aligned with the second alignment through hole (16) of an adjacent electrical plate.

11. The electrical plate (2) has a height D from the base of the electrical plate in the direction of the adjacent insulating layer (18). ＰＳ and the alignment element (30) has at least one protruding structure protruding at a height h ｂ is the height D of the protruding structure ＰＳ 11. A battery stack (1) according to any of the preceding claims, designed such that:

12. 12. A battery stack (1) according to any of the preceding claims, wherein the alignment elements (30) are made from an electrically insulating material, preferably a plastic material, and preferably the alignment elements (30) are moulded, preferably injection moulded.

13. 2. The cell stack (1) of claim 1, wherein the cell stack (1) is a fuel cell stack (1), the electrical plates (2) are bipolar plates (BPP) consisting of an anode plate and a cathode plate fixed to each other, and the insulating layer (18) is a membrane electrode assembly (MEA).

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