Fuel cell stack, fuel cell device and fuel cell vehicle

Abstract

Fuel cell stack (1) comprising a plurality of fuel cells (3) which are received between two end plates (2) in a housing (4), and comprising a clamping device (5), wherein the housing (4) is formed on each side by at least two spaced-apart clamping struts (6) serving to clamp the fuel cells (3), between which sealing plates (7) with a lower density than the clamping struts (6) are arranged to bridge the gap and seal the housing (4), characterized in that the sealing plates (7) are attached and sealed against the clamping struts (6) with an adhesive layer.

Description

[0001] The invention relates to a fuel cell stack comprising a plurality of fuel cells mounted between two end plates in a housing, and to a clamping device. The housing is formed on each side by at least two spaced-apart clamping struts serving to clamp the fuel cells. Between these struts, sealing plates with a lower density than the clamping struts are arranged to bridge the gap and seal the housing. The invention further relates to a fuel cell device and a fuel cell vehicle.

[0002] Fuel cells are used to generate electrical energy through an electrochemical reaction. To increase usable power, several fuel cells can be connected in series to form a fuel cell stack. Each fuel cell comprises an anode, a cathode, and a proton-conducting membrane separating the anode and cathode. This membrane is coated with a catalyst to promote the electrochemical reaction. Furthermore, in a fuel cell stack, each fuel cell has bipolar plates on both sides of the membrane to supply the reactants and, if necessary, a coolant. Gas diffusion layers are also used to distribute the reactants supplied by the bipolar plates as evenly as possible across the entire surface of the catalyst-coated membrane.

[0003] This plurality of fuel cells grouped in a fuel cell stack is generally pressed together using tensile elements with a force in the range of several tons in order to achieve sufficient contact pressure on the catalyst-coated membrane to reduce ohmic losses and to avoid leaks of the seals used by means of the high compression.

[0004] DE 10 2019 219 782 A1 discloses, by way of example, a fuel cell stack formed from individual cells, which is clamped between two end plates by means of a clamping device made of carbon fiber composite material with a low coefficient of thermal expansion. WO 02 / 27836 A2 discloses a fuel cell stack characterized by a large number of fuel cells. To prevent buckling, a stabilizing sleeve is used in the central area along its longitudinal direction, which utilizes tension struts or tension straps running transversely to the longitudinal direction as connecting elements. DE 10 2020 213 317 A1 discloses a fuel cell stack in which angle bars are arranged at the corners as part of a shell surface, connected on each side of the shell surface by struts. Cover elements are inserted between adjacent angle bars.It is known from DE 10 2018 210 176 A1 to weld clamping elements to end plates.

[0005] The fuel cell stacks are arranged in a housing made of a metallic cast or sheet metal part to separate them from the environment, whereby the high mass is particularly disadvantageous in a mobile application.

[0006] The object of the present invention is to design a fuel cell stack in such a way that it can be constructed with a lower mass. A further object is to provide an improved fuel cell device and an improved fuel cell vehicle.

[0007] This problem is solved by a fuel cell stack with the features of claim 1, by a fuel cell device with the features of claim 8, and by a fuel cell vehicle with the features of claim 9. Advantageous embodiments with expedient further developments of the invention are specified in the dependent claims.

[0008] The fuel cell stack is characterized by the provision of a hybrid housing with reduced mass, in which large surface areas of the housing are formed by a lightweight material, which is also used for sealing the housing, with the sealing plates being attached and sealed to the tension struts with an adhesive layer to achieve the desired tightness.

[0009] For improved mechanical stability, it is advisable to assign a tension strut to each corner of the housing.

[0010] The tension struts are made of a metallic material in order to provide the tensioning function permanently with sufficient compression.

[0011] The sealing plates are made of a plastic that provides a lightweight, low-density material.

[0012] The sealing plates can be arranged in a plane with the tensioning struts between them, or the sealing plates can be arranged overlapping with the tensioning struts on them.

[0013] The tension struts and end plates are preferably made of steel or a steel alloy and / or welded and / or bolted together.

[0014] The aforementioned advantages and effects also apply analogously to a fuel cell vehicle with a fuel cell device having such a fuel cell stack, which has increased reliability and effectiveness over the entire lifespan of the fuel cell stack, in particular because the reduced mass reduces energy consumption and thus increases the range.

[0015] The features and combinations of features mentioned above in the description, as well as the features and combinations of features mentioned below in the figure description and / or shown in the figures alone, can be used not only in the combination specified in each case, but also in other combinations or on their own.

[0016] Further advantages, features, and details of the invention will become apparent from the claims, the following description of preferred embodiments, and the drawings. These show: Fig. 1 a schematic representation of a fuel cell stack with tension struts as load-bearing cell row tensioning elements and the associated sealing plates of the housing, and Fig. 2 an exploded view of a fuel cell stack arranged in a housing according to the invention in the configuration as a duo-stack.

[0017] In the Fig. Figure 1 schematically shows a fuel cell stack 1 consisting of a plurality of fuel cells 3 connected in series, arranged inside a housing 4 of the fuel cell stack 1 between two end plates 2.

[0018] Each of the fuel cells 3 comprises an anode and a cathode, as well as a proton-conducting membrane separating the anode from the cathode. The membrane is formed from an ionomer, preferably a sulfonated tetrafluoroethylene polymer (PTFE) or a polymer of perfluorinated sulfonic acid (PFSA).

[0019] Fuel (for example, hydrogen) is supplied to the anodes via anode compartments within the fuel cell stack 1. In a polymer electrolyte membrane fuel cell (PEM fuel cell), fuel or fuel molecules are split into protons and electrons at the anode. The membrane allows the protons (for example, H₂) to be released. + ) through, but is impermeable to electrons (e - The following reaction takes place at the anode: 2H₂ → 4H₂ + + 4e -(Oxidation / Electron Release). While the protons pass through the membrane to the cathode, the electrons are conducted to the cathode or to an energy storage device via an external circuit. Cathode gas (for example, oxygen or oxygen-containing air) can be supplied to the cathodes via cathode compartments within the fuel cell stack 1, so that the following reaction takes place on the cathode side: O₂ + 4H₂ + + 4e - → 2H2O (reduction / electron uptake).

[0020] Fig. Figure 1 schematically shows such a fuel cell stack 1 with a plurality of fuel cells 3, which are accommodated between two end plates 2 in the housing 4. A clamping device 5 serves to achieve sufficient contact pressure on the catalyst-coated membrane to reduce ohmic losses and to prevent leaks by means of the high compression. In the illustrated embodiment, the housing 4 is formed on each side by at least two spaced-apart clamping struts 6 for the clamping device 5, which serve to mechanically clamp the fuel cells 3. Between these clamping struts, sealing plates 7 with a lower density than the clamping struts 6 are arranged to bridge the gap and seal the housing 4.The tension struts 6 are assigned to at least each corner 8 of the housing 4, with the sealing plates 7 being attached and sealed to the tension struts 6 by an adhesive layer. In the illustrated embodiment, the sealing plates 7 are arranged in a plane with the tension struts 6 between them. Alternatively, the sealing plates 7 can be arranged overlapping the tension struts 6 on top of them (not shown). These designs ensure good sealing of the housing 4, so that the requirements for protection classes for splash protection or water resistance can also be met. Graphite particles can optionally be added to the sealing plates 7 to improve electromagnetic compatibility.

[0021] The tension struts 6 are made of a metallic material, in particular steel or a steel alloy, and the same material can be chosen for the end plates 2, so that the metallic components of the housing 4 can be welded together. The sealing plates 7 are made of a plastic to achieve a low density.

[0022] It is not only possible to arrange a fuel cell stack 1 in the housing 4. Fig. Figure 2 shows an embodiment with a duo-stack, i.e., two separately formed fuel cell stacks 1 which are accommodated in the housing 4, so that the housing 4 requires a larger surface area and the advantages of the housing design become particularly evident.

[0023] The result is a hybrid housing with topology-optimized end plates 2 and clamping struts 6, combined with lightweight plastic sealing plates 7. The clamping device 5 is part of the housing 4 and does not require springs; thermal insulation is either unnecessary or only partially required, as the thermal insulation is already improved by the plastic sealing plates 7.

[0024] Such a fuel cell stack 1 unfolds its advantages particularly in a fuel cell device intended for use in a fuel cell vehicle. REFERENCE MARK LIST 1 fuel cell stack 2 End plate 3 Fuel cell 4 cases 5 Clamping device 6 tension strut 7 Sealing plate 8 corner

Claims

[1] Fuel cell stack (1) comprising a plurality of fuel cells (3) which are received between two end plates (2) in a housing (4) and comprising a clamping device (5), wherein the housing (4) is formed on each side by at least two spaced-apart clamping struts (6) serving to clamp the fuel cells (3), between which sealing plates (7) with a lower density than the clamping struts (6) are arranged to bridge the gap and seal the housing (4), characterized by , that the sealing plates (7) are attached and sealed against the tension struts (6) with a layer of adhesive. [2] Fuel cell stack (1) according to claim 1, characterized by , that each corner (8) of the housing (4) is assigned a tension strut (6). [3] Fuel cell stack (1) according to claim 1 or 2, characterized by that the tension struts (6) are made of a metallic material [4] Fuel cell stack (1) according to any one of claims 1 to 3, characterized by , that the sealing plates (7) are made of a plastic. [5] Fuel cell stack (1) according to any one of claims 1 to 4, characterized by that the sealing plates (7) are arranged in a plane with the tension struts (6) between them. [6] Fuel cell stack (1) according to any one of claims 1 to 4, characterized by that the sealing plates (7) are arranged overlapping with the tension struts (6) on these. [7] Fuel cell stack (1) according to any one of claims 3 to 6, characterized by , that the tension struts (6) and the end plates (2) are made of steel or a steel alloy and / or are welded and / or bolted together. [8] Fuel cell device with a fuel cell stack (1) according to any one of claims 1 to 7. [9] Fuel cell vehicle with a fuel cell device according to claim 8.

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