FUEL CELL AND FUEL CELL SYSTEM

Abstract

A fuel cell comprises a polymer electrolyte membrane, an anode electrode being associated with said membrane on the first side thereof and a cathode electrode being associated with said membrane on the second side thereof, wherein a gas diffusion layer is associated with each of the electrodes on the side thereof that faces away from the polymer electrolyte membrane, and wherein a flow field plate having a flow field for distributing the reactants is associated with each of the gas diffusion layers on the side thereof that faces away from the polymer electrolyte membrane, characterized in that at least one conducting line formed from a hygroscopic and/or capillary-active material is provided for conducting water and thus for moistening the polymer electrolyte membrane.

Claims

1. A fuel cell, comprising: a polymer electrolyte membrane; an anode electrode on a first side of the polymer electrolyte membrane; a cathode electrode on a second side of the polymer electrolyte membrane; an anode gas diffusion layer on a side of the anode electrode that faces away from the polymer electrolyte membrane; a cathode gas diffusion layer on a side of the cathode electrode that faces away from the polymer electrolyte membrane; an anode flow field plate having an anode flow field for distributing an anode reactant on a side of the anode gas diffusion layer that faces away from the polymer electrolyte membrane; a cathode flow field plate having a cathode flow field for distributing a cathode reactant on a side of the cathode gas diffusion layer that faces away from the polymer electrolyte membrane; and at least one conducting line formed from a hygroscopic and/or capillary-active material for conducting water and thus for moistening the polymer electrolyte membrane.

2. The fuel cell according to claim 1, wherein the at least one conducting line is aligned parallel to or identical to a reactant channel of the flow field.

3. The fuel cell according to claim 1, wherein the at least one conducting line extends perpendicular to a reactant channel of the flow field.

4. The fuel cell according to claim 1, wherein the at least one conducting line is embedded in the polymer electrolyte membrane.

5. The fuel cell according to claim 1, wherein the at least one conducting line is embedded in the gas diffusion layer.

6. The fuel cell according to claim 5, wherein the at least one conducting line extends along a flow field web separating two reactant channels of the flow field from each other.

7. The fuel cell according to claim 6, wherein the dimensions of the at least one conducting line are adapted to the dimensions of the flow field web.

8. The fuel cell according to claim 1, wherein the at least one conducting line is connected in a fluid-mechanical manner to a reactant outlet.

9. The fuel cell according to claim 1, wherein the at least one conducting line is connected in a fluid-mechanical manner to an outlet of a water extractor arranged in an anode exhaust line.

10. A fuel cell system comprising a plurality of fuel cells connected in series, each of the fuel cells comprising: a polymer electrolyte membrane; an anode electrode on a first side of the polymer electrolyte membrane; a cathode electrode on a second side of the polymer electrolyte membrane; an anode gas diffusion layer on a side of the anode electrode that faces away from the polymer electrolyte membrane; a cathode gas diffusion layer on a side of the cathode electrode that faces away from the polymer electrolyte membrane; an anode flow field plate having an anode flow field for distributing an anode reactant on a side of the anode gas diffusion layer that faces away from the polymer electrolyte membrane; a cathode flow field plate having a cathode flow field for distributing a cathode reactant on a side of the cathode gas diffusion layer that faces away from the polymer electrolyte membrane; and at least one conducting line formed from a hygroscopic and/or capillary-active material for conducting water and thus for moistening the polymer electrolyte membrane.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0020] Further advantages, features and details will be apparent from the claims, the following description of embodiments, and from the drawings.

[0021] FIG. 1 shows a schematic cross-sectional view of a first fuel cell,

[0022] FIG. 2 shows a schematic cross-sectional view of a second fuel cell,

[0023] FIG. 3 shows a schematic cross-sectional view of a third fuel cell,

[0024] FIG. 4 shows a schematic cross-sectional view of a fourth fuel cell, and

[0025] FIG. 5 shows a fuel cell system with a fuel cell stack comprising a plurality of fuel cells according to FIGS. 1 to 4.

DETAILED DESCRIPTION

[0026] FIGS. 1 to 4 show a fuel cell 1.

[0027] The fuel cell 1 comprises a polymer electrolyte membrane 2, an anode electrode 3 being associated with said membrane on the first side thereof and a cathode electrode 4 being associated with said membrane on the second side thereof, wherein a gas diffusion layer 5 is associated with each of the electrodes 3, 4 on the side thereof that faces away from the polymer electrolyte membrane. This gas diffusion layer 5 likewise also comprises a microporous layer 10 which gives the gas diffusion layer 5 a lower porosity on its side facing the polymer electrolyte membrane 2. A flow plate 6 with a flow field for distributing the reactants is associated with each of the gas diffusion layers 5 on their side facing away from the polymer electrolyte membrane 2. In some embodiments, at least one, or several, conducting lines 7 formed from a hygroscopic and/or capillary-active material are present in the fuel cells 1 for conducting water and thus for moistening the polymer electrolyte membrane 2.

[0028] As shown in FIG. 1 and FIG. 3, it is possible for the at least one conducting line 7 to be embedded in the polymer electrolyte membrane 2. Alternatively, or additionally, as shown in FIG. 2 and FIG. 4, there is the possibility that the at least one conducting line 7 is embedded in the gas diffusion layer 5. In this case, at least one or more of the conducting lines 7 can be assigned to each of the gas diffusion layers 5, as shown in FIG. 2.

[0029] As evidenced by the fuel cells according to FIG. 1 and FIG. 2, the conducting line 7 is aligned parallel to or identical to a reactant channel 8 of the flow field of the flow field plate 6, such that there is an “along the channel” configuration for the conducting line 7. In the example according to FIG. 2, in which the at least one conducting line 7 is embedded in the gas diffusion layer 5, the conducting line 7 extends along one flow field web 9 of the flow field separating two of the reactant channels 8 from each other. The dimensions of the at least one conducting line 7 are adapted to the dimensions of the flow field web 9, so that no further “dead zones” are created by embedding the conducting line 7 in the gas diffusion layer 5.

[0030] The configurations according to FIG. 3 and FIG. 4 show the possibility that the at least one conducting line 7 may also extend perpendicular to one of the reactant channels 8 of the flow field, thus providing a configuration that is “in plane.”

[0031] FIG. 5 shows a fuel cell system 100 with a plurality of fuel cells 1 connected in series according to FIGS. 1 to 4. As a core component, the fuel cell system 100 comprises a fuel cell stack 102, which has a plurality of fuel cells 1 arranged in stack form, not shown in more detail here. In order to supply the fuel cell stack 102 with the fuel, the fuel cell stack 102 is connected on the anode side to an anode supply line 104 for supplying a hydrogen-containing anode gas from an anode reservoir 106 via a heat exchanger 108, such as in the form of a recuperator. The anode operating pressure on the anode side of the fuel cell stack 102 is adjustable via an actuator 110 in the anode supply line 104. On the anode outlet side, there is an anode exhaust line 112, which is fluid-mechanically connected to an anode recirculation line 114 which in turn is fluid-mechanically connected to the anode supply line 104 for removal of unreacted anode gas. On the anode side, a separator, in particular a water extractor 116, is furthermore present in the anode recirculation line 114, the outflow of which is fluid-mechanically connected to the at least one conducting line 7 by means of a fluid supply line 118, in order to thus moisten the polymer electrolyte membrane 2 with the water collected in the separator via the conducting line 7. Alternatively, the conducting line 7 can also directly suction the liquid accumulating at the reactant outlet 130.

[0032] On the cathode side, the fuel cell stack 102 is connected to a cathode supply line 120 for supplying the oxygen-containing cathode gas. A compressor 26 is connected upstream of the cathode supply line 120 to convey and compress the cathode gas. In the configuration shown, the compressor 122 is implemented as a principally electric motor-driven compressor 122, the propulsion of which occurs by means an electric motor equipped with corresponding power electronics, which is not shown in more detail.

[0033] The cathode gas which has been suctioned in from the environment by means of the compressor 122, is conducted directly via the cathode supply line 120 to the fuel cell stack 102. On the cathode outlet side, a cathode exhaust line 124 is provided for discharging the cathode exhaust gas.

[0034] In addition, a bypass line 126 is provided downstream of the compressor 122. The bypass line 126 fluid-mechanically connects the cathode supply line 126 to the cathode exhaust line 124 for adjusting the mass flow of cathode gas flowing through the cathode supply line 126 by means of an actuator 128.

[0035] 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.