DE102006051320A1 - Fuel cell i.e. direct methanol fuel cell, arrangement, has anode and cathode with medium permeable interlayer to diaphragm unit over channel structures, where interlayer covers channels of one structure and includes intermediate segments - Google Patents

Abstract

The arrangement has a diaphragm unit (2) with an anode (3) and a cathode (4) arranged on opposite sides. The anode and cathode include channel structures (5, 6) for laminar media distribution and segments (7) for isolated measurement of electrical characteristics. The anode and cathode include a medium permeable interlayer (8) to the diaphragm unit over the channel structures. The interlayer covers channels (9) of the channel structure (6). The interlayer includes intermediate segments corresponding to the segments (7). Independent claims are also included for the following: (A) a test station including a fuel cell arrangement (B) a method for manufacturing a fuel cell arrangement.

Description

The The present invention relates to a fuel cell assembly as well a process for their preparation.

The uniform distribution of the electrical current density or the metabolic rate in an electrochemical cell is important for high efficiency, reliable operation and a long lifetime of the fuel cell assembly. The knowledge of this distribution allows many insights into the operation of an electrochemical cell. This is first and foremost the optimal design of the flow field, which must ensure that the operating fluids and coolant are optimally distributed, the humidifying state of a membrane is set correspondingly well and evenly low contact resistance occurs. In fuel cells with two-phase transport, for example, direct methanol fuel cells (DMFC), where in addition to methanol, the resulting CO ₂ must be discharged in the anode compartment, in addition to the operation management also the construction of the flow field plays a crucial role.

It is therefore very desirable while the development phase of fuel cells is a suitable instrument to analyze the current density distribution. So will one Optimization of the design and operation of the electrochemical cell possible. This allows also quality fluctuations be analyzed by membrane materials and catalyst coatings.

requirement but is that the method of spatially resolved current density measurement a sufficiently high resolution owns and only a very small constructive difference of all the mass transport influencing characteristics between the measuring device and the fuel cell assembly of the later product. The Measurement method itself should therefore have no effect on the fuel cell assembly / electrochemical Cell have.

In the DE 102 13 478 A1 For example, a method for determining or specifying the current density distribution and the spatially resolved metabolic rate in electrochemical reactions is realized by dividing one of the electrodes into segments isolated from each other and connecting each segment to a separate current source or current sink dedicated to the operation of the electrochemical reaction an integrated circuit, which is switched as a Kostantspannungsquelle.

The individual segments of the electrode and the connection of the segments with the integrated circuits are realized with multilayer printed circuit boards. On the top of the circuit board thus creates a matrix-shaped field the individual segments in the form of metallization pads. Even if with the known fuel cell assembly, a segmental investigation electrical properties is desired, but so the media flow is limited because it can only be done around the segments, and these only a little Height (less than 1 mm) and one due to the very limited distance between the segments has very small channel cross-section. In particular, through the existing conductivity the gas diffusion layer (GDL) laterally in the plane of the plane there is a balance between the segments (possibly short-circuit effects).

Of the The present invention is therefore based on the object, in the spatially resolved Measurement of the current density distribution in fuel cells, a fuel cell assembly in which the measurement setup is the channel structures as little as possible influences and thus the behavior of regular anodes / cathodes if possible real pictures.

These Task is governed by the objects of independent claims solved.

A Fuel cell arrangement according to the invention contains a membrane unit with a part of the membrane unit arranged Anode and a cathode disposed on the other hand, the membrane unit, wherein the cathode and / or the anode each have a channel structure to the plane Media distribution and segments for isolated measurement of electrical Have properties in these segments. According to the invention, at least one has the electrodes (cathode and / or anode) to the membrane unit on or over their structures at least partially a media-permeable liner on. This intermediate layer covers at least partially channels the respective channel structure. The liner also points to the electrically separated segments corresponding interposing segments which are also substantially electrically isolated from each other are.

In this way, it is thus ensured that on the one hand "real" channel structures with relatively large channel cross-sectional areas can be provided which correspond to the flow behavior of media in "real" channel structures of an anode or a cathode. Despite these channel structures, the electrical connection of the respective electrode to the membrane unit is as large as possible. This is because the corresponding intermediate layer covers the channel structures and thus contact the membrane unit over a large area of electrically conductive (and preferably correspondingly stiff) sections of the intermediate layer. The fact that the liner au ßerdem is designed to be permeable to media, can be secured by appropriate slots and / or eg by a correspondingly porous structure, the unhindered passage of media through the intermediate layer to the membrane unit. On the one hand, the desired large-area connection to the membrane unit is secured, on the other hand, the size of the channel structures is not adversely affected by measuring segments and finally, by the corresponding isolation of the individual segments from each other a meaningful current density measurement possible.

The Fuel cell arrangement according to the invention is suitable for example as a test arrangement. This can be done at the less critical electrode of the test setup with the segmented Electrode be housed. For example, in a methanol-powered Fuel cell in which methanol is supplied on the anode side and cathode-side air, the measuring structure be mounted on the cathode side, because the distribution of air in the channel structures rather uncritical and therefore requires less optimization than the methanol supplied Anode side. Well, you can In such a construction, different channel structures for the anode are "tried" and the respective ones electrical properties in the individual segments can then be detected accordingly with the measurement setup on the cathode side. This leads to meaningful Results showing both the overall efficiency of the fuel cell as well as the goodness of Determine distribution in the critical anode channel structure. By Targeted optimization in segments with unsatisfactory measurement results can then the anode structures are optimized.

ever However, according to the principle of fuel cell arrangement can also anode side Be given measuring setups. For example, with a gaseous Hydrogen fuel cell may make sense be to accommodate the appropriate measurement setup at the anode and to compare different cathode channel structures. in this connection It is always important that the measurement side of the later real (or in series manufactured) fuel cell assembly should be as similar as possible, because only so correspondingly usable results come out.

Of course it is but it is also possible on both sides of the electrode (ie at anode and at cathode) corresponding Segmentation.

Finally is does not limit the application of the present fuel cell assembly on test operation or development operation. It also can make sense, a corresponding segmentation in a series prepared fuel cell assembly to provide. hereby for example Malfunctions or blockages are indirectly detected well. Furthermore can be a corresponding regulation of the media supply depending on the measurement results targeted in individual segments, for example, a "siphoning" of the fuel cell assembly to prevent. Especially with big industrialists Application, the number of segments can be kept correspondingly small could be, for example it be sufficient there, in a single-channel execution of the Channel structure (for example in the form of a meander) only to attach one segment at the beginning and at the end of the channel structure, which are then compared with each other metrologically.

in principle are different electrical properties of the individual segments measurable. It can, for example, at a prescribed current the corresponding voltage drop can be measured. Of course they are also specified voltage differences or spatially resolved measurement. the cell impedance is possible. It is only important that in each case conclusions about the electrical power in the individual segments (both relative and absolute) are possible. In this case, the measurement takes place with a relatively high quality, since the segments essentially are electrically isolated from each other and therefore no short-circuit effects given in area plane which could adversely affect the measurement results.

Summarized can therefore be said that for spatially resolved Measurements of the current density distribution in fuel cells in which one or both electrodes divided into segments isolated from each other and each segment with its own for the operation of the electrochemical Reaction provided power source or sink is connected the main problem is, despite the multitude of individually executable ones Current conductor to form a channel structure with the later product preferably is identical and a low electrical cross between owns the individual segments.

The problem is solved according to the invention by distributing conductive vertical paths distributed matrix-like in a channel structure (flow field) consisting of insulating material. At the upper side facing the membrane unit, at the upper end of the conductive paths, an intermediate layer, preferably a conductive microchannel structure, is conductively connected, covering almost the entire membrane surface like a segment and interconnected by thin isolation zones. On this microchannel structure, a likewise segmented structured gas diffusion layer or even catalyst layer can be applied. The liner or Microchannel structure is mechanically stable enough to apply a uniform contact pressure on the membrane unit (fuel cell membrane.

Finally are another independent objects given. This concerns, for example, a test subject containing a fuel cell arrangement according to the invention, wherein this test stand is a measuring structure for inserting the fuel cell assembly and one with segments of the inserted fuel cell assembly understandable connectable evaluation unit.

Further is also a method for producing an embodiment of a Inventive fuel cell assembly shown. This is to produce a first electrode (anode or cathode) a metal plate with an array of pins (one) in the foot area the metal pins provided with an insulating plate. this happens for example by pouring a polymer layer of an insulating plastic. The metal plate is then on the insulation board repellent side structured and connections from individual metal pins (one) to a corresponding printed circuit board assembly produced. The pins, which then go up to the electrical Stand out contact, then be with a segmented liner provided, which is applied to these pins. following is a membrane unit on the pins repellent side of the Attached intermediate system and on the other side of the membrane unit again a supplementary one Electrode (anode or cathode) attached.

This is, however, only an exemplary production method, especially for very Small scale fuel cell assemblies are also microstructured Produce fuel cell assemblies, in which process from Semiconductor technology can be used (this will be later once detailed).

advantageous Further developments of the present inven tion are given in the dependent claims.

A advantageous development provides that the intermediate layer as continuous liner executed which is electric between individual interposer segments has insulating regions. You can for electrically insulating, porous substrates with adequate media permeability (fiber materials, fabrics, porous glasses or ceramics used in the Segment of segments were made electrically conductive sections or the overall conductive are, but only in z-direction, perpendicular to the membrane, so it to no cross currents between the segments can come.

In an alternative embodiment is the liner of physical constructed from separate intermediate layers segments. In this Case columns are provided between the interleaving segments. These are for electrical isolation only and should be preferably be as small as possible size contract area to provide the membrane unit ready.

Especially It is advantageous that the spacer segments to the membrane unit towards, but not necessarily adjacent to, a microchannel structure exhibit. This is good for maintaining the contact pressure to the membrane unit and therefore to improve the efficiency. The The finest distribution towards the membrane unit is provided by the microchannel structure guaranteed. The channel width of microchannels the microchannel structure is in this case preferably 20 to 500 micrometers, particularly preferably 20 to 100 microns.

These Microchannel structure may vary depending on the medium or membrane unit or Size of the channels directly connect to the membrane unit or even an additional about the same size and have segmented gas diffusion layer according to the segments.

A Another advantageous embodiment provides that the segments the anode and / or cathode pins (one) for electrical connection having an associated circuit board assembly. This circuit board arrangement is used to connect to operational amplifiers or integrated circuits and thus allows a space-saving connection of the segments corresponding further measuring technology.

Basically each of the segments has its own circuit, with the current, voltage or resistance measurement can be performed regulated.

The corresponding pins of the anode and the cathode are preferably arranged in a corresponding insulating plate, which to the PCB assembly is easily attachable. The electrical connection the conductive one Pins of the segments with the corresponding contacts of the circuit board takes place about by electrically conductive Adhesives or anisotropically conductive Adhesives, by contact mats (only in the z-direction, i.e. perpendicular to the membrane unit plane, conductive) or by soldering.

The pins are preferably embedded in corresponding channel structures. These channel structures consist for example of a cast epoxy resin, the corresponding channel structures can be shown as side-by-side parallel channels or as a meandering structure. Alternatively, the pins may be isolated (pin-fin array).

The channel width of the channels in the channel structures is preferably 0.5 to 5 mm, here is always sufficient space for gaseous or liquid media. For most applications, it has been found that an aspect ratio of 1: 1, that is, the channel depth is approximately equal to the channel height, has been found to be sufficient. Only with a variant with freestanding pins (see for example 3 in the description below), it may be necessary to make the height of the pins larger than their mutual distance (up to about 10x higher), if so natural convection or only small forced air movement at the cathode is to be simulated.

The segments for measuring the electrical properties, which are given in the anode or the cathode, respectively adjacent surfaces of the membrane unit between 0.2 and 10 mm ² , preferably between 0.5 and 1.5 mm ² . Overall, a wide variety of fuel cell applications are possible, preferably a DMFC or a PEMFC will be given. The electrochemically active region of a single cell of this fuel cell arrangement should in this case have between 4 and 400 mm ² .

It should, even if PEM and DMFC possible Areas of application are, no limitation on these concepts be. The invention is suitable for any form of fuel cell planar membranes and planar cell-plate assemblies (in different to fuel cells with a tubular structure). In addition to fuel cells with polymer membrane, the invention can also be used for micro fuel cells, e.g. made of silicon, or for High temperature fuel cells (SOFC, MCFC) or alkaline fuel cells with liquid electrolyte be used. The structure then only needs to be compatible with compatible, temperature-stable materials.

Especially is advantageous if in a corresponding test arrangement the Anode and or the cathode are designed interchangeable. Preferably, respectively the electrode at which just not indicated the measuring segments are. This can be different Electrodes are tested with their corresponding channel structures.

Especially However, it is also advantageous if the fuel cell arrangement having a measuring and / or regulating device. That's it too possible an online self-regulation for regular Produce fuel cell assemblies, with which the fuel cell assembly each can be operated in an optimal range and before All malfunctions can be indirectly detected in this way are.

A Particularly advantageous development provides that in particular wide channels and / or wide webs in the channel structures through these channels and / or web areas several summarized segments are characterized. So can a channel, for example, by a maximum of 2 adjacent segments be characterized. In this way one obtains a spatially resolved measurement in the cross section of a single web / channel.

A particularly advantageous development of the production method according to the invention provides that resilient contact pins are fitted into an insulating plate (or into a substrate), onto which prefabricated intermediate layer segments are plugged. In this case, the segments can be mounted partially movable on the contact pins, whereby they compensate for manufacturing tolerances alone. The spring force is calculated according to the number of segments so that the desired contact pressure can be set (50 ... 200 N / cm ² ). It can also spring contact pins are used, which have at the same time up and down spring contacts and thus simultaneously contact the circuit board below.

Further advantageous developments are given in the remaining dependent claims.

in the The invention will be explained with reference to several figures. It demonstrate:

1 FIG. 2: a cross section of a fuel cell arrangement according to the invention,

2a to 2d FIG. 2 shows various production steps of an electrode according to the invention using the example of a cathode, FIG.

3 : another example of a cathode according to the invention,

4 : A plan view of an intermediate layer according to the invention and

5 and 6 Further embodiments of the erfingunsgemäßen fuel cell assembly.

1 shows the cross section of a fuel cell assembly according to the invention, which is designed as DMFC (direct methanol fuel cell). Above a membrane unit 2 is an anode 3 attached with a canal structure 5 , Zwi the channel structure 5 and the membrane unit 2 an anode-side gas diffusion layer is attached. In the fuel cell assembly according to the invention 1 Among other things, it is about testing different anode types with different channel structures with regard to a uniform media feed over the entire surface.

This is the anode 3 interchangeable disposed in the fuel cell assembly. An air driven cathode is below the membrane unit 2 shown.

This cathode 4 has an insulating plate 16 of a polymer material which is electrically insulating. Within this insulating plate is a matrix of electrically conductive pins 14 made of metal. These pins are each individually with a printed circuit board assembly 15 electrically connected. The circuit board arrangement in turn is connected to a measuring and / or regulating device for measuring electrical properties, in particular for measuring an electrical voltage. On the other hand, this measuring and / or regulating device is also connected to the membrane unit 2 or the anode 3 connected. This makes it possible for every single pen and for each segment associated with that pen 7 taken by itself electrical properties, for example to measure a voltage drop. By providing an entire array of corresponding segments, the field distribution of a given electrical property, such as the voltage drop, can be determined over a large area (essentially over the entire electrochemically active area of the cathode), depending on a particular currently inserted anode 3 , The pins (contact pins) are embedded in an insulator having channel structures (this may be a polymer, a filled polymer or a composite, but also glass or ceramic). As a result, on the cathode side, a media guide allows relatively wide channels 9 , This is not conditional on the width of the channels 9 too little contact surface with the membrane unit 2 and therefore an inefficient or meaningless cathode is provided between the top of the channel structure 6 or the upper ends of the pins 14 on the one hand and the membrane unit 2 on the other hand, a media-permeable liner 8th appropriate. In the present case, this medially permeable intermediate layer is made up of physically separate intermediate layer segments 10 constructed (alternatively, the intermediate layer could also be designed as a continuous intermediate layer, which, however, would then have electrically insulating areas between individual intermediate layers segments).

The interleaved segments 10 consist of Mikrokanal- or lattice structures with a large aperture ratio, so that (at the cathode), the oxygen can be distributed evenly over the entire segment and the resulting water vapor in the underlying channels of the channel structure (the actual flow field) can be derived.

In the 1 shown fuel cell assembly is merely an example to understand. Thus, the subdivision according to the invention into segments which are electrically insulated from one another can also be given purely on the anode side in order to then carry out corresponding experiments, for example with different cathodes. Of course, it is also possible to provide corresponding segments on both sides (ie at the anode and cathode).

1 thus shows a fuel cell assembly 1 containing a membrane unit 2 with an anode arranged on the one hand of the membrane unit 3 and a cathode disposed on the other side of the membrane unit 4 wherein the cathode and / or the anode each have a channel structure 5 respectively. 6 for the area-wide distribution of media as well as segments 7 for isolated measurement of electrical properties in these segments. The cathode and / or the anode have to the membrane unit through its channel structures at least partially a media-permeable intermediate layer 8th on, with these liner channels 9 the respective channel structure 6 at least partially covered and the intermediate layer 8th to the segments 7 corresponding liner segments 10 which are substantially electrically isolated from each other.

The fuel cell arrangement according to the invention can be represented in various sizes. The electrochemically active region preferably has an area between 4 and 400 cm ² on. The channel width of the channels 9 in the channel structures 6 is preferably 0.5 to 5 mm. The segments 7 (or present the largest extension of the spacer segments 10 , measured at the respective outer edges of the microchannel structures 11 ) each have areas between 0.2 and 10 mm ² , preferably 0.5 to 1.5 mm ² . The channel widths of the microchannels 12 the microchannel structure 11 (See in particular 2d , there on the right) each have dimensions of 20 to 50 micrometers, preferably 20 to 100 micrometers.

Even if the present 1 only the fuel cell arrangement itself in a cross-section shows (this is a fuel cell arrangement substantially square in plan view of the membrane unit, which essentially looks the same in an orthogonal section), but a so-called test stand is also part of the invention. Such a test stand contains in addition to the invention Brenn fuel cells arrangement 1 a measuring structure for inserting the fuel cell assembly and a connectable to segments of the inserted fuel cell array evaluation.

The following is an example of a production method for the fuel cell assembly according to the invention 1 shown. For this purpose, first for producing a first electrode, for example, the in 1 shown cathode, a metal plate with an array of pins 14 in the foot area of the metal pins with an insulating plate 16 made of a polymer layer. The metal plate is then patterned on the insulating plate repellent side and connections from individual pins to a corresponding circuit board assembly (for example, the in 1 shown circuit board assembly 15 ) produced. The pencils 14 protrude upwards for electrical contacting and are subsequently provided with a segmented intermediate layer 8th (For example, microchannel structures 11 arranged thereon with portions of gas diffusion layers) applied to these pins, for example by gluing, soldering or welding. The following is a membrane unit 2 and attached to the side facing away from the membrane unit of the cathode, a corresponding anode.

In the just described method, the pins could 14 partially free-standing (Pin-Finn-Array). During the manufacturing process, however, it is also possible to pour this area of the pins in an insulating material to create appropriate channel structures. In this case, for example, a complete pouring the space between the pins can be provided and then carried out by mechanical processing or laser ablation, the production of the corresponding channels. For smaller channel heights (less than 1 mm), a solid resist can also be laminated on and the channels are subsequently produced by photo-structuring. To get a flat, clean surface of the metal pins 14 To ensure the surface of the entire part is possibly ground and polished. The distance and the grid of matrix-shaped metal pins 14 must be chosen so that the metal pins are always only in the area of the webs between the channels, as they would otherwise affect the mass transfer in the channels.

The manufacturing process is again in the 2a to 2d illustrated.

2a Here, on the right side, shows a plan view of an insulating plate 16 with inserted pins 14 , which are already isolated on the underside of the insulating plate for connection to a corresponding circuit board assembly.

2 B shows the arrangement 2a , meanwhile channel structures 6 with channels 9 were prepared by casting with a polymer, such as epoxy resin, the subsequent structuring in the spaces between the pins was done by laser ablation.

2c shows the arrangement 2 B , wherein substantially square microchannel structures 11 on the tops of the pins 14 are set up. Every pin 14 corresponds to a single electrical segment 7 , which is measurable independently of the other segments. The top-mounted square microchannel structure 11 is electric with the pin 11 connected and even made of an electrically conductive and media-permeable material.

In 2d then again the arrangement is off 2c shown, pointing to the microchannel structure 11 each a gas diffusion layer was placed with a corresponding square section (s. 2d , left side). In 2d , right side is a microchannel structure 11 with microchannels 12 shown which to underlying pins 14 each followed.

In the 2d shown gas diffusion layer sections are electrically conductive, to avoid short circuits and a "blurring" of the measurement result, therefore, the gas diffusion layer in the in 2d divided segments shown. However, the mechanical stiffness of a single segment is usually too small to pass through the pins 14 mediated contact pressure evenly distributed to the middle of the channel area. Therefore, the microchannel support structures are necessary. They have a high me chanical rigidity and at the same time the highest possible opening ratio (ratio of the open areas between the webs to the width of the webs), so that the transport of the reactants is not hindered.

The microchannel structure 11 (or an equivalent lattice structure) itself can first be generated on a contiguous substrate. This is done by mechanical processing, laser structuring or etching a thinner metal plate (about 100-500 microns). The production can also be achieved by electrodeposition. The result is a grid structure with a high aperture ratio and high rigidity. In order to achieve a necessary rigidity, in addition to the choice of metal or alloy, the ratio of thickness to external dimensions (distance between two channels) also plays a role 12 , Length of the channels or length of the segment) a crucial role.

Subsequently, the microchannel structure 11 with the metal pins 14 by soldering, spot welding ßen or electrically conductive bonding connected. Subsequently, the flatness of the micro-channel structure can be checked and possibly improved by post-processing. The separation between the individual segments now takes place by means of mechanical processing (sawing with a thin saw blade) or by laser processing.

On This way, there will be a very small distance between each one Segments guaranteed. To prevent corrosion, the entire metal structure with a precious metal (preferably gold) or otherwise (such as with conductive Polymers) coated. The material used must be in the Fuel cell should be corrosion resistant and should have a low contact resistance have.

The sections of gas diffusion layer, which in 2d on the microchannel structures 11 is applied, for example, can be glued in the middle of a segment with a glue point (this is in 2d , indicated on the right). Are the lattice structures of the microchannel structure 11 sufficiently small (10-200 microns) can be dispensed with corresponding gas diffusion layer segments also. However, the gas diffusion layer can also first be applied across the gingiva and then separated between the individual segments (for example by sawing or laser cutting).

Next The exemplary arrangement shown here are also examples for smaller ones Given dimensions according to the invention.

For producing a fuel cell arrangement with smaller dimensions, for example, a separating or sacrificial layer is applied to a substrate (silicon wafer, glass, metal, ceramic) (by spinning or spraying). On this layer, a full-surface metal layer is applied (by sputtering or Glavanik). Subsequently, a substrate film (this would be in 1 the insulating plate 16 correspond) is produced by laminating a polymer film or a spin-on a polymer precursor and cured. For example, a sheet of Kapton ^® (registered trademark of DuPont) is used, or is spun on a generic polyimide. Then matrix-shaped openings for plated-through holes are produced. For example, Kapton can be patterned by laser or reactive ion etching (RIE). Photosensitive polyimide is instead exposed, developed and cured. With the help of the lower full-area metallization, a metallic plated-through hole is then produced by galvanic deposition from the lower side to the upper side of the foil. In the next step, a thickness photosensitive resist mask is applied, exposed and developed and galvanically the studs or "stud bumps" 14 produced. Just before the metal deposition reaches the surface of the resist, a second photoresist is applied, exposed and developed, and the microchannel structure 11 (see, for example 2d ) galvanically produced. Subsequently, the upper and the lower resist are removed (paint "stripping"). The metal structures are freed of polymer residues by means of RIE and galvanically coated with a corrosion-resistant layer (preferably gold).

Finally, the insulating plate / substrate film is removed from the carrier substrate by dissolving the sacrificial layer and the plating base is removed by etching. In this way, the pitch of the segments 100 Microns or even smaller. Thus, a very high resolution is achieved and, in particular, micro-fuel cells which are produced using microsystem technology can undergo corresponding test procedures for suitable anodes or cathodes, or achieve a very high spatial resolution, for example individual channels / bridges, in the case of larger fuel cells.

Main Applications for measurements with Fuel cell assemblies according to the invention affect DMFC or PEM.

A Channel structure according to the invention is preferably used as a cathode. This creates a simpler Overall construction, as the segmented arrangement is not sealed got to.

at DMFC uses the segmented channel structure as the cathode side to supply defined oxygen or air. On the anode side can now quickly different channel geometries are tested, the at different Operating conditions achieve a homogeneous current density. It can also draw conclusions the two phases transport (transport of carbon dioxide bubbles) determined become.

at PEM, the segmented channel structure is preferably used for hydrogen transport. On the cathode side different channel geometries are tested an optimization for to find the oxygen or water transport.

Should Fuel cells are examined while oxygen is passing through natural Convection of the ambient air takes place, so can an open structure be used at the cathode.

4 shows in deviation to the in 1 shown intermediate layer, a plan view of an intermediate layer, which is on the one hand media permeable, but on the other hand between individual spacer layers 10 has insulating regions. As a result, a lateral current between the be adjacent segments avoided thereby a significantly improved signal separation between individual segments is achieved.

5 relates to a specific embodiment, which broader channels 9 and / or wider webs of the channel structure. Here is for example in 5 , top left, shown that inter alia segments are grouped into subunits.

6 shows an embodiment in which resilient pins 21 in the actual contact pins 14 are installed. Unlike the example in 5 shown, substantially rigid in the longitudinal direction, contact pins, these are in the height direction (ie towards the membrane unit back) essentially "self-balancing". Prefabricated spacer segments can also be attached to the corresponding pins.

Claims (21)

Fuel cell assembly ( 1 ) containing a membrane unit ( 2 ) with an anode arranged on the one hand of the membrane unit ( 3 ) and on the other hand the membrane unit arranged cathode ( 4 ), wherein the cathode and / or the anode each have a channel structure ( 5 . 6 ) for the areal media distribution as well as segments ( 7 ) for the isolated measurement of electrical properties in these segments, characterized in that the cathode ( 4 ) and / or the anode ( 3 ) to the membrane unit over its channel structures at least partially a media-permeable intermediate layer ( 8th ), said intermediate layer channels ( 9 ) of the respective channel structure ( 6 ) at least partially covered and the intermediate layer ( 8th ) to the segments ( 7 ) corresponding spacer segments ( 10 ), which are substantially electrically isolated from each other. Fuel cell arrangement according to claim 1, characterized in that the intermediate layer ( 8th ) is designed as a continuous intermediate layer, which between individual intermediate layer segments ( 10 ) has electrically insulating regions. Fuel cell arrangement according to claim 1, characterized in that the intermediate layer ( 8th ) is constructed of physically separate spacer segments. Fuel cell arrangement according to one of the preceding claims, characterized in that the spacer segments ( 10 ) to, but not necessarily adjacent to, a microchannel structure ( 11 ) exhibit. Fuel cell arrangement according to claim 4, characterized in that the channel width of microchannels ( 12 ) of the microchannel structure is 20 to 500 micrometers, preferably 20 to 100 micrometers. Fuel cell arrangement according to one of the preceding claims, characterized in that the intermediate layer ( 8th ) to the membrane unit ( 2 ) immediately adjacent one to the segments ( 7 ) correspondingly segmented gas diffusion layer ( 13 ) having. Fuel cell arrangement according to one of the preceding claims, characterized in that the segments ( 7 ) of the anode ( 3 ) and / or the cathode ( 4 ) Pencils ( 14 ) for electrical connection to an associated circuit board assembly. Fuel cell arrangement according to claim 7, characterized in that the pins ( 14 ) of anode ( 3 ) and / or cathode ( 4 ) in a respective insulating plate ( 16 ) are arranged. Fuel cell arrangement according to one of claims 7 or 8, characterized in that the pins ( 14 ) are embedded in insulating webs of the flow field or the channel structures ( 6 ). Fuel cell arrangement according to one of claims 7 or 8, characterized in that the pins ( 14 ) are freestanding. Fuel cell arrangement according to one of the preceding claims, that the segments ( 7 ) of anode ( 3 ) and / or cathode ( 4 ) each have surfaces between 0.2 and 10 mm ² , preferably 0.5 to 1.5 mm ² . Fuel cell arrangement according to one of the preceding claims, characterized in that the channel width of the channels ( 9 ) in the channel structures ( 6 ) Is 0.5 to 5 mm. Fuel cell assembly according to one of the preceding Claims, characterized in that it comprises a direct methanol fuel cell, a with gaseous Hydrogen fuel cell or other fuel cell is. Fuel cell arrangement according to one of the preceding claims, characterized in that it has an area between 4 and 400 cm ² in the electrochemically active region. Fuel cell arrangement according to one of the preceding claims, characterized in that the anode ( 3 ) and / or the cathode ( 4 ) is designed to be interchangeable [if, for example, in a test arrangement different channel structures this is useful on the side opposite to the "measurement page". Fuel cell assembly according to one of the preceding Claims, characterized in that this is a measuring and / or regulating device having. Fuel cell assembly according to one of the preceding Claims, characterized in that at wide channels and / or wide webs in the channel structures these channels and / or web areas characterized by a plurality of combined segments become. Test stand containing a fuel cell assembly according to one of the preceding claims, which has a measuring structure for inserting the fuel cell assembly and one with segments the inserted fuel cell assembly connectable evaluation identifies. Method for producing a fuel cell arrangement according to one of the preceding claims, wherein initially for producing an anode ( 3 ) or cathode ( 4 ) a metal plate with an array of pins ( 14 ) in the foot region of the metal pins with an insulating plate ( 16 ) and the metal plate is then patterned on the side facing away from the insulating plate and connections from individual pins to a corresponding printed circuit board assembly ( 15 ), so that the pens ( 14 ) protrude upward for electrical contacting and then a segmented intermediate layer ( 8th ) is applied to these pins and subsequently a membrane unit ( 2 ) and on the opposite side of the membrane unit a supplementary cathode ( 4 ) or anode ( 3 ) is attached. A method according to claim 19, characterized in that during production of the anode ( 3 ) or cathode ( 4 ) the pins are poured into a channel structure made of insulating material. A method according to claim 19, characterized in that in an insulating ( 16 ) resilient pins ( 21 ) are fitted on the prefabricated spacer segments are plugged.