FUEL CELL ASSEMBLY, FUEL CELL SYSTEM, AND FUEL CELL VEHICLE

Abstract

A fuel cell assembly is provided comprising a membrane electrode assembly that includes a membrane and a first electrode, which is arranged on a first side of the membrane and to which a first gas diffusion layer is assigned. The fuel cell assembly further includes a frame and an adhesive layer directly bonding the membrane electrode assembly to the frame at least in certain areas at an edge area of the membrane electrode assembly. The adhesive layer penetrates the first electrode, and the membrane is directly bonded to the frame as a result of this penetration. A fuel cell system and a fuel cell vehicle comprising such a fuel cell assembly are also provided.

Claims

1. A fuel cell assembly, comprising: a membrane electrode assembly including: a membrane; a first electrode arranged on a first side of the membrane and to which a first gas diffusion layer is assigned; and a second electrode arranged on a second side of the membrane opposite to the first side of the membrane and to which a second gas diffusion layer is assigned; a frame; and an adhesive layer directly bonding the membrane electrode assembly to the frame, wherein the adhesive layer is present at least in certain areas at an edge area of the membrane electrode assembly, wherein the adhesive layer penetrates the first electrode, and wherein the membrane is directly bonded to the frame as a result of the penetration, and wherein the adhesive layer has a first adhesive layer section connecting the membrane at the edge area to the frame and a second adhesive layer section connecting the membrane at the edge area to the second gas diffusion layer.

2. The fuel cell assembly of claim 1, wherein the first electrode has a porosity configured such that the adhesive layer fully penetrates the first electrode to bond the frame to the membrane.

3. The fuel cell assembly according to claim 1, wherein the adhesive layer has a viscosity selected to completely penetrate the first electrode to bond the frame to the membrane.

4. The fuel cell assembly according to claim 1, wherein the adhesive layer has a surface energy and/or surface tension selected so that the adhesive layer completely penetrates the first electrode to bond the frame to the membrane.

5. (canceled)

6. The fuel cell assembly according to claim 1, wherein the membrane and the electrodes are formed in lateral extension with an identical surface area.

7. The fuel cell assembly according to claim 6, wherein the frame comprises a recess with a flow cross section whose surface area is smaller than the lateral surface area of the membrane.

8. The fuel cell assembly according to claim 6, wherein a first sealing layer that circumferentially seals the first gas diffusion layer is assigned to the frame on a first frame side, and a second sealing layer that circumferentially seals both the second gas diffusion layer and the membrane is assigned to the frame on a second frame side that is opposite the first frame side.

9. A fuel cell system including a fuel cell assembly comprising: a membrane electrode assembly including: a membrane; and a first electrode arranged on a first side of the membrane and to which a first gas diffusion layer is assigned; a frame; and an adhesive layer directly bonding the membrane electrode assembly to the frame, wherein the adhesive layer is present at least in certain areas at an edge area of the membrane electrode assembly, wherein the adhesive layer penetrates the first electrode, and wherein the membrane is directly bonded to the frame as a result of the penetration.

10. A fuel cell vehicle having a fuel cell system including a fuel cell assembly comprising: a membrane electrode assembly including: a membrane; and a first electrode arranged on a first side of the membrane and to which a first gas diffusion layer is assigned; a frame; and an adhesive layer directly bonding the membrane electrode assembly to the frame, wherein the adhesive layer is present at least in certain areas at an edge area of the membrane electrode assembly, wherein the adhesive layer penetrates the first electrode, and wherein the membrane is directly bonded to the frame as a result of the penetration.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0023] Further advantages, features, and details will be apparent from the claims, from the following description of embodiments, and from the drawing.

[0024] FIG. 1 shows a cross-sectional view of a fuel cell assembly.

DETAILED DESCRIPTION

[0025] FIG. 1 shows a fuel cell assembly with a membrane electrode arrangement 1, which comprises a semipermeable membrane 2 with a first electrode 3 on its first side 4 and with a second electrode 5 on its second side 6 that is opposite the first side 4. In this, the first electrode 3 may be formed as an anode and the second electrode 5 may be formed as a cathode. There is, however, also the possibility that the first electrode 3 forms the cathode and the second electrode 5 forms the anode of the membrane electrode assembly 1. The membrane 2 may be coated on the first side 4 and on the second side 6 with a catalyst layer made of noble metals or mixtures comprising noble metals such as platinum, palladium, ruthenium or the like, which serve as reaction accelerators in the reaction of the fuel cell. The respective catalyst layer is thereby an integral part of the corresponding electrode 3, 5 or forms the electrode itself.

[0026] In such a polymer electrolyte membrane fuel cell (PEM fuel cell), fuel or fuel molecules, in particular hydrogen, are split into protons and electrons at the first electrode 3 (anode). The membrane 2 allows the protons (e.g., H.sup.+) to pass through, but is impermeable to the electrons (e). The membrane 2 is formed from an ionomer, such as a polytetrafluoroethylene polymer (PTFE) or a polymer of perfluorosulfonic acid (PFSA). The membrane 2 can alternatively be formed as a sulfonated hydrocarbon membrane. In this case, the following reaction occurs at the anode: 2H.sub.2.fwdarw.4H.sup.++4e.sup.− (oxidation/electron release).

[0027] While the protons pass through the membrane 2 to the second electrode 5 (cathode), the electrons are conducted to the cathode or to an energy storage device via an external circuit. A cathode gas, in particular oxygen or oxygen-containing air, is provided at the cathode, so that the following reaction takes place there: O.sub.2+4H.sup.++4e.sup.−.fwdarw.2H.sub.2O (reduction/electron capture).

[0028] A first gas diffusion layer 7 is assigned to the first electrode 3 and a second gas diffusion layer 8 is assigned to the second electrode 5. The gas diffusion layers may be made of carbon fiber paper (CFP). Standard dimensions keep the manufacturing complexity for the individual components of the fuel cell assembly 1 as limited as possible. For this reason, the membrane 2 has a (cross-sectional) surface area in lateral extension which corresponds to that of the electrodes 3, 5.

[0029] To improve a fluid or gas flow within the fuel cell assembly and to increase a water content in the membrane, a first microporous layer 20 is assigned to the first gas diffusion layer 7 on its side facing the first electrode 3. Likewise, a second microporous layer 21 is assigned to the second gas diffusion layer 8 on its side facing the second electrode 5. The lateral dimensions of the microporous layers 20, 21 correspond substantially to the lateral dimensions of the respective gas diffusion layers 7, 8.

[0030] To increase the stability of the fuel cell assembly, a frame 11 with a recess 12 is arranged between the first electrode 3 and the first gas diffusion layer 7. An active area 14 of the membrane electrode arrangement 1 can be predefined by a flow cross section 13 defined by the recess 12.

[0031] At the same time, the flow cross section 13 of the recess 12 has a smaller surface area than the surface area of a flow cross section 15 of the second gas diffusion layer 8. The flow cross section 33 of the first gas diffusion layer 7 substantially corresponds to the flow cross section 15 of the cross section of the second gas diffusion layer 8 oriented orthogonally to the stacking direction.

[0032] The membrane electrode assembly 1 has an edge area 9 on the outer circumference side. The edge area 9 of the membrane electrode assembly 1 is understood to be an area of the membrane electrode assembly 1 surrounding the outer circumference side of the membrane electrode assembly 1 and extending parallel and in part orthogonally to the stacking direction.

[0033] An adhesive layer 10 is provided for a firm bonding of the frame 11 to the membrane electrode assembly 1. The adhesive layer 10 bonds the frame 11 directly to the membrane 2 of the membrane electrode assembly. In this, the first electrode 3 is completely penetrated by material of the adhesive layer 10, for which it may have a suitable porosity. In the same way, the membrane 2 of the membrane electrode assembly 1 can also be directly bonded in the edge area 9 to the second gas diffusion layer 8 by the adhesive layer 10, wherein the second electrode 5 is here also provided with suitable porosity and is completely penetrated by material of the adhesive layer 10.

[0034] The adhesive layer 10 herein laterally surrounds the membrane of the membrane electrode arrangement 1 in the edge area 9, which is to say on the outer circumference side; in particular, in a complete manner. The adhesive layer 10 thereby has a U-shaped or C-shaped cross section and is formed from a first adhesive layer section 16 and a second adhesive layer section 17. The first adhesive layer section 16 bonds—through the first electrode 3—the membrane 2 in an edge area 9 of the membrane electrode arrangement 1 to an inner edge area 18 of the frame 11 near the recess 12. The inner edge area 18 of the frame 11 is thereby formed as a partial area of the frame 11 extending outward on the inner circumference side. The second adhesive layer section 17 bonds the second gas diffusion layer 8—through the second electrode 5—to the membrane 2 in the edge area 9 of the membrane electrode assembly 1. Beyond this, a second adhesive layer 19 is provided which bonds the inner edge area 18 of the frame 11 to the first gas diffusion layer 7. During assembly of the fuel cell assembly, the two adhesive layer sections 16 and 17 coalesce to form a common adhesive layer 10 with a monolithic structure.

[0035] A first bipolar plate 27 which is attached to or assigned to the first gas diffusion layer 7 and provides an anode gas flow field 28 is provided on the anode side for the supply of fuel to the first electrode 3. Furthermore, a second bipolar plate 29 for supplying the cathode gas is assigned to the second gas diffusion layer 8 on the cathode side and has a cathode gas flow field 30. The cathode gas is fed through the second gas diffusion layer 8 to the second electrode 5 by the cathode gas flow field 30.

[0036] The lateral extension, which is to say, the extension perpendicular to the stacking direction, of the bipolar plates 27, 28 is greater than that of the gas diffusion layers 7, 8 and corresponds substantially to that of the frame 11. A first sealing layer 22 is arranged between a first frame side 23 of the frame 11 and the first bipolar plate 27 and seals the first gas diffusion layer 7 on the circumference side. A second sealing layer 24 is provided between a second frame side 25 of the frame and the second bipolar plate 28. The sealing layers 22, 24 are formed as compressible sealing lips, each of which is provided multiple times laterally. In the present embodiment example, three sealing lips are provided laterally in each case, which sealing lips are arranged on the circumference side around the first gas diffusion layer 7 and the second gas diffusion layer 8. Thus, the first sealing layer 22 and the second sealing layer 24 each have a total of six of the sealing lips. Another number is possible. In this, the sealing lips of the first sealing layer 22 have a larger diameter than the sealing lips of the second sealing layer 26.

[0037] Beyond this, a first channel 31 and a second channel 32, both extending in the stacking direction through the first bipolar plate 27, the second bipolar plate 29 and the frame 11, are provided laterally to the membrane electrode assembly 1, first channel 31 for supplying the fuel, second channel 32 for supplying the cathode gas to the fuel cell assembly. The channels 31, 32 are arranged within the fuel cell assembly in such a way that, on the side facing the gas diffusion layers 7, 8, in each case two sealing lips of the first sealing layer 22 and in each case two sealing lips of the second sealing layer 24 are arranged inside and, on the side opposite thereto, in each case one sealing lip of the first sealing layer 22 and one sealing lip of the second sealing layer 24 are arranged outside.

[0038] On the basis of the penetration of the electrodes 3, 5 with the material of the adhesive layer 10, a suitable pairing of contact partners results, since both the membrane 2 and the adhesive layer 10 are made of a polymer, which leads to an improved adhesive bond. Since the frame 11 can also be formed of a polymer, such an enhanced adhesive effect is also seen at the contact surface of the frame 11 with the adhesive layer 10. This leads overall to an even more stable fuel cell assembly, which at the same time exhibits improved sealing.

[0039] Aspects of the various embodiments described above can be combined to provide further embodiments. These and other changes can be made to the embodiments in light of the above-detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled.