EP1706914A2 - Electrochemical cell arrangement having a pocket-shaped structure - Google Patents

Electrochemical cell arrangement having a pocket-shaped structure

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Publication number
EP1706914A2
EP1706914A2 EP20040804231 EP04804231A EP1706914A2 EP 1706914 A2 EP1706914 A2 EP 1706914A2 EP 20040804231 EP20040804231 EP 20040804231 EP 04804231 A EP04804231 A EP 04804231A EP 1706914 A2 EP1706914 A2 EP 1706914A2
Authority
EP
Grant status
Application
Patent type
Prior art keywords
folding
cell
pockets
electrolyte
electrode
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP20040804231
Other languages
German (de)
French (fr)
Inventor
Maria Acosta
Gerhart Eigenberger
Clemens Merten
Gerhard Friedrich
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Stuttgart Universitaet
Original Assignee
Stuttgart Universitaet
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date

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Classifications

    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL INTO ELECTRICAL ENERGY
    • H01M8/00Fuel cells; Manufacture thereof
    • H01M8/10Fuel cells with solid electrolytes
    • H01M8/1009Fuel cells with solid electrolytes with one of the reactants being liquid, solid or liquid-charged
    • H01M8/1011Direct alcohol fuel cells [DAFC], e.g. direct methanol fuel cells [DMFC]
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL INTO ELECTRICAL ENERGY
    • H01M8/00Fuel cells; Manufacture thereof
    • H01M8/02Details
    • H01M8/0271Sealing or supporting means around electrodes, matrices or membranes
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL INTO ELECTRICAL ENERGY
    • H01M8/00Fuel cells; Manufacture thereof
    • H01M8/10Fuel cells with solid electrolytes
    • H01M8/1007Fuel cells with solid electrolytes with both reactants being gaseous or vaporised
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL INTO ELECTRICAL ENERGY
    • H01M8/00Fuel cells; Manufacture thereof
    • H01M8/10Fuel cells with solid electrolytes
    • H01M8/1016Fuel cells with solid electrolytes characterised by the electrolyte material
    • H01M8/1018Polymeric electrolyte materials
    • H01M8/1065Polymeric electrolyte materials characterised by the form, e.g. perforated or wave-shaped
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL INTO ELECTRICAL ENERGY
    • H01M8/00Fuel cells; Manufacture thereof
    • H01M8/24Grouping of fuel cells, e.g. stacking of fuel cells
    • H01M8/241Grouping of fuel cells, e.g. stacking of fuel cells with solid or matrix-supported electrolytes
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL INTO ELECTRICAL ENERGY
    • H01M8/00Fuel cells; Manufacture thereof
    • H01M8/04Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04007Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids related to heat exchange
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/50Fuel cells
    • Y02E60/52Fuel cells characterised by type or design
    • Y02E60/521Proton Exchange Membrane Fuel Cells [PEMFC]
    • Y02E60/522Direct Alcohol Fuel Cells [DAFC]
    • Y02E60/523Direct Methanol Fuel Cells [DMFC]

Abstract

The invention relates to an electrochemical stack of cells, preferably a stack of cells for membrane fuel or membrane electrolysis-cells, formed from several parallel or serially connected individual cells. All cathode sides of the individual cells and all anode sides of the individual cells are disposed in pockets which are formed by a meandering, folded electrolyte layer and are closed on the upper and lower front surfaces thereof. The individual cells are made of, in a manner known per se, electrodes comprising downstream and/or upstream conductors, in addition to, optionally, backing and current distributors on both sides of the electrolyte layer. The individual downstream and/or upstream conductors are electrically connected thus producing a serial or parallel connection. Then, the anode fluid and/or the cathode fluid is supplied to or evacuated from all open pockets on the anode and/or cathode side of the anode and/or cathode chamber without the need for individual distribution and sealing, normally in a parallel plate stack, of successive cells. Instead, the area between the anode and cathode chamber is sealed by the folded electrolyte layer and the two front-sided sealing elements.

Description

The electrochemical cell assembly in pocket-shaped design

The invention relates to an electrochemical cell stack (Stack), preferably a cell stack for Membranbrennstoff- or membrane electrolysis cells formed from multiple parallel or series-connected single cells, wherein all the cathode sides of the individual cells and all anode sides of the single cells are arranged in pockets concertina fashion or by a . maanderformig folded electrolyte layer are formed and which are closed at their upper and lower end faces. Which single cells are constructed in a known manner from downstream passageway or Zuleitern electrodes and optionally backing and flow distributors on both sides of the electrolyte layer, wherein the downstream passageway or individual feeders can be electrically interconnected so that a series or parallel connection is obtained. Then, supply or discharge of the anode fluid and said cathode fluid for all the anode or cathode side of the anode or cathode compartment open bags can be carried out in each case together without the usual stack in a parallel plate single distribution and sealing of successive cells would be required. Instead, the seal between the anode and cathode compartments by the folded electrolyte layer and the two end seals is ensured. The invention thus relates to a novel structure of an electrochemical cell stack, the pels in comparison with the conventional construction according to the principle of a Parallelplattensta- in particular by a simple, common accessibility of all anode and cathode compartments, a simplified sealing and mechanical by a lower voltage stress and a distinguishes lower space consumption of the electrolyte material.

In electrochemical cells electrochemical reactions occur at the electrodes from through Elektronenzu- or discharge, in which either consumes electrical energy or is generated. In both cases, individual cells are suitably electrically connected one behind the other so that the required or generated electric voltage is a multiple of the individual cell voltage. The series-connected cells are arranged expediently in the form of a compact cell stack ( "Stack").

The most widespread is the parallel-plate stack are arranged in the single cells with planar electrodes and electrolyte layers one after the other so that the electrode and the current conductor of successive cells to bipolar electrodes or bipolar plates are combined. but the anode fluid and cathode fluid must then be separated from each other, distributed over the anode or cathode compartments of each individual cell and be withdrawn therefrom, wherein the electrode spaces each of flow channels between the electrolyte and one side of the bipolar electrode or bipolar plate are formed. This requires a complex flow control and distribution as well as reliable sealing of the individual electrodes fluids against each other and to the outside. Both are accomplished by distributing frame between the individual cells and connected to the frame or launched seals. The necessary sealing pressure all of the individual cells must be pressed together to-for example, by tie rods and end plates massive. This can induce mechanical stresses in the electrolyte layers, which can lead to mechanical failure. Because polymer electrolyte membranes swell differently depending on the water content of the electrode fluids or shrinking, this can also result in a rigid input voltage of the membrane to membrane failure. In addition, the inlet and outlet channels are often passed through apertures within the electrolyte layers through the entire cell stack. This means that a considerably greater electrolyte layer area is needed in comparison to the electrochemically active surface.

Fig. 1 shows the typical structure of a membrane fuel cell stack using the example of a polymer membrane fuel cell. The cell stack 10 comprises a plurality of repeat units each comprising a bipolar plate 6, two seals 8 and the membrane electrolyte layer 20 with the applied on both sides, catalyst-coated electrodes 38th At both ends of the end plates 7 are provided in which the holes 4 are mounted for guiding the tie rod. These tie rods of the disc stack is clamped together amount to apply the necessary forces for the sealing gaskets. 8 By the compression of the (elastic) seals 8 stresses in the electrolyte membranes 20 can be induced, which eventually lead to cracks. These are enhanced when (as with polymer membrane fuel cells) swell the electrolyte membranes under changing humidification different. The channels 32 serve to supply and discharge of the electrode fluids and, optionally, coolant and the distribution of the electrodes fluids to the electrode chambers on both sides of the electrolyte membrane 20 to penetrate the electrolyte membranes 20 and thus reduce the effective area of ​​the electrode surface 38th

From US 2003 / 0108783A1, a fuel cell is known, the electrolyte layer in the form of edges of flaps are folded in starting from the conventional parallel plate design, so that they facilitate the sealing of the electrodes and the separation of the two electrodes fluids. This is to account for both sides of the electrolyte layer, the gaskets. However, this is a risk that the electrolyte layer tears at the folded and pressed by the tie rod corners increases. In addition, the land use of electrolyte membrane material increases by the folding.

Although found in the technical and patent literature numerous proposals on how each some of those mentioned disadvantages of parallel plate stacks can be reduced, their aforementioned principal disadvantages are unavoidable in principle.

Another way to go, the so-called planar cell concepts in which a continuous separating layer separates the anode from the whole entire cathode compartment. From DE 43 29 819 A1 such an electrochemical cell is known, which is in the form of a strip membrane. In FIG. 2, the operating principle for the case of the polymer electrolyte membrane (PEM) fuel cell is illustrated. The strip membrane consists of consecutive electrolytic layer elements 36, each applied on both sides of the electrolyte layer 20, electrodes 38, as well as contact 34 and insulating members anode 14 and cathode space 16 are located on opposite sides of the strip membrane and have to be sealed to the outside and against one another. the anode of one cell with the cathode of the adjacent cell by the contact elements 34 is respectively connected to each other for the series circuit. Furthermore described in DE 43 29 819 A1 also a stepped assembly for series interconnection of the individual cells. This eliminates the contact and insulating elements and the electrodes 38 take over the function of the downstream passageway or feeders.

Since the contacting of the individual cells via the edges of the contact resistance is large. To solve the problem, in DE 195 39 959 C2 a different version for a fuel cell assembly is described. Its principle is shown in Fig. 3. In this arrangement, a continuous electrolyte layer 20 is used. For series connection of the electrodes 38, these are spatially one behind the other applied to both sides of the electrolyte layer 20 and electrically separated from each other and respectively feed line 34 connected to one another via the edges by downstream passageway. The entire electrode surface is contacted by current collector plates 38th The anode fluid then flows respectively on the one hand, the cathode fluid on the other side of the planar electrolyte layer 20 and has outwardly and sealed relative to the other electrode fluid.

Because of the high surface area required planar concepts have been limited to electrochemical cells less power.

From US 5,709,961 and US 6,054,228 a (membrane) fuel cell system is known, which is based on a modified planar array. In contrast to FIG. 3, the electrolyte layer is not formed continuously. Rather, there is a planar array of a sequence of (metallic) Bipolarrahmen 9, which are arranged imbricated overlapping, and between which in each case separate electrolyte layers are 20, as shown in Fig. 4. The anode chamber 14 is always on one side of the cathode chamber 16 on the back of the device. are so-called gas barrier, a sort of flat gaskets 8 for the separation of the two electrodes fluid spaces, integrated on the side sealed to one another in the electrode 38th The planar arrangement can also be folded in and sealed to the side. This results in a closed pocket, for example, the anode fluid (hydrogen), while the cathode fluid (air) flows around the bag from the outside. Multiple pockets can be stacked with the respective supply and discharge lines for the anode fluid and electrically connected. Overall, the described arrangement is also production-technically complex and potentially error-prone by the diffizilen roof tile-like structure and the many sealing surfaces between the electrolyte layer and Bipolarrahmen.

The present invention thus has for its object to provide an electrochemical cell assembly in which, in contrast to the conventional parallel plate stack concepts, as shown in Fig. 1, the sealing of the cells is achieved without the application of a sealing force, and the electrolyte layer surface used is better utilized. Further, a compact volume without a large space needed to in contrast to the planar arrays, as shown in FIGS. 2 to 4 can be obtained. In contrast to the tile-like structure with stacked bags as shown in FIG. 4, also aims to achieve a simpler structure with fewer sealing surfaces and simple flow guidance.

This object is achieved by the features characterized in the claims embodiments.

According to the present invention is an electrochemical cell, in particular PEM fuel cell or electrolytic cell provided, which is characterized in that a fixed, gas-tight, containing electrolyte layer (20) ( "diaphragm") in a housing (48, 49) either maanderformig is folded or so piecewise gas-tightly connected together so that meander-shaped folding pockets (12) are formed, that these folding pockets (12) at their end faces (19) against the neighboring pockets and / or the housing are sealed, so that the entire pocket space on one side the convolution ( "anode compartment") (14) from the entire pocket space of the other side of the fold ( "cathode compartment") (16) is separated and flows through all folding pockets of the anode space from an anode fluid and all folding pockets of the cathode compartment from a cathode fluid separately or overflows be and the electrolyte layer (20) on both sides of the folding pockets in a conventional manner with electric odenkatalysator (22), backing (24) flow, field (30) and downstream passageway or zuleitern is provided (34), so that a sequence of membrane electrode units (EMEs) (26) is formed, and initiating the downstream or feeders (34) each are EME. electrically so with the Stromabbzw, zuleitern adjacent EMEs connected, that depending on the requirements an electrical parallel or series connection of the individual EMEs is generated.

In a preferred embodiment of the present invention, a gas-tightly enclosed by the membrane-electrode space is formed in that the or is gas-tightly connected to one end of the pleated membrane to the other end of the pleated membrane that a plurality of membrane folds are connected at their ends gas-tight manner. In a specific embodiment of the present invention, the folding is arranged around a cylindrical core, that the folding pockets (12) protrude star-shaped from the core, and one electrode chamber (14) inward to the cylindrical core and the other electrode chamber (16) by is open outwardly and, optionally, an outer housing (48) encloses the folding assembly cylinder.

In a further embodiment of the present invention, the electrode chambers at the end faces (19) of the folding arrangement, and optionally the common housing by potting material (18) are sealed gas-tight, wherein the potting compound, for example, an elastically-curable polymer composition, such as in particular an elastically curable silicon-containing polymer composition, a ceramic composition or a solder is used and the adhesion of the casting compound to the elements to be sealed, optionally by pre-treatment (primer, adhesion promoter, etc.) is ensured or improved.

In yet another embodiment of the present invention, the EMEs (26) are electrically connected in series, for which purpose the downstream passageway or feed line (34) of the two EME halves are in each folding pocket (12) electrically insulated from each other and their electrical connections, either by the sealing compound out to the outside (18) at the end faces (19) or through the lateral opening of the folding pockets and are connected there with the terminals of the downstream passageway or feed line (34) of the adjacent bags.

Preferably, the downstream passageway or feed line (34) are profiled or composed of several elements that they form flow channels (32) for the directed flow through the folding pockets (12). In the folding pockets (12) elements for the purpose of directed flow guide (flow field, (30)) and / or for electrical supply and downstream passageway (34) to be installed to elastically deform on lateral pressure as soon as (via the housing 49) exerting a lateral pressure force (50) on all the folding pockets (12), so that the impressed spring tension of these elements for a permanently good mechanical contact between the electrolyte layer (20), catalyst layer (22), backing (24) and Stromabbzw, zuleitern ( 34) provides. Moreover, can be arranged which are flowed through by a heat transfer fluid at predetermined folding pockets (12) devices for heat dissipation or feed, wherein the supply and discharge of the heat transfer gerfluids via lines through the potted end faces (19) or through the side pocket openings takes place. According to the invention, heat removal may be provided in that the downstream passageway or feed line (34) further lying in the folding pockets faces or cooling fins (52) formed and by the potted end faces (19) or the side pocket openings are led outward. The anode fluid and / or the cathode fluid can be fed via feed channels (40) in the side pocket openings further flow inside the folding pockets (12) in the direction of the end faces (19) and are drawn off through discharge channels (42) in the side pocket openings. Alternatively, the cathode fluid and / or the anode fluid can be parallel to the end faces (19) through the folding pockets (12) flows, wherein the base of each folding pocket a collecting channel (44) receiving the electrode fluid or distributed and the electrode fluid over a certain height of the folding pockets (12) these flows, from the collecting channel (44) is taken up and deflected and flows back over a certain height of the folding pockets. However, the cathodes fluid and / or the arrival can be parallel to the end surfaces (19) through the folding pockets flow (12) and from a collecting channel (44) odenfluid also over the entire height of the folding pockets (12) was added to each folding pocket at the bottom or distributed wherein the collecting channel (44) is passed through one or both of the potted end faces (19) and collecting channels all have their common inlet and outlet in a connection head outside the potted end faces (19).

Another object of the present invention is a polymer membrane fuel cell which is designed such that the air and optionally also the combustion gas, respectively on an absorbent, porous structure (46) is placed on the folding pockets (12) pressed into this folding pockets or is sucked and humidified thereby and the absorbent porous structure (46), either periodically impregnated with water or is on a side in contact with water, so that the water is distributed by capillary action independently and uniformly over the porous structure (46). Preferably, the porous structure (46) may be arranged on or between the protruding out of the pockets of the cathode side cooling fins (52), that the humidification of the air takes place at approximately the temperature of the cooling fins.

Yet another object of the present invention is a direct methanol fuel cell which is designed such that the anode compartment (14) is filled with the liquid methanol-water mixture and the carbon dioxide bubbles formed during the anode reaction by forced or natural convection with the methanol water mixture to be transported from the anode bags (12).

The electrochemical cell assembly of the invention starts from a plana- ren arrangement according to FIG. 3. However, the foreseen in the present invention, electrolyte layer is in each case folded maanderformig between the individual electrodes so that folding pockets are formed. This folding pockets are sealed at their end faces against the neighboring pockets and the housing so that the entire pocket space is isolated on one side of the fold ( "anode chamber") of the whole pocket space on the other side of the fold ( "cathode compartment"). All the bags of the anode or cathode space are separated from the anode and cathode fluid flow through and parallel to each other. The electrolyte layer or zuleitern on both sides of the folding pockets in a known manner with electrode catalyst and downstream passageway and optionally backing and flow guide ( "flow field") is provided. In the case of membrane fuel cells produced in this way a series of electrode-membrane-electrode units (EMEs). the downstream passageway or feed line into the folding pockets can be brought out and electrically connected to each other so that there is, as required, a parallel or series connection of individual cells formed between two folding pockets. in series circuit are to initiating the downstream feeders or double run in each pocket and against each other to electrically isolate. in this way, a compact design with high power density is produced.

The folding pockets are arranged in a housing, so that two mutually gas-tightly sealed spaces are formed in the housing. The case still has usually appropriate allocations for both electrodes fluids on the respective sides.

The meander-shaped fold according to the invention the electrolyte layer lends itself to flexible electrolyte layers, especially in polymer electrolyte membranes. In brittle electrolyte layers a similar bag construction can be gas-tightly connected to each other be achieved in that the flat electrolyte walls of each pocket at one or three page (s). One of the ion current interrupting compound has thereby reliably prevent the additional advantage of cross-currents (ion currents through the electrolyte) between the individual cells.

The anode and cathode fluid is usually distributed in parallel to all the anode and cathode pockets. The flow guide within the respective rule can Faitta- through between the electrodes and downstream passageway or feeders arranged spacers (spacer) and flow guides (flow fields) are facilitated. These elements can also be combined in one component, for example, by profiling of the downstream passageway or feeders. The folding arrangement is enclosed by a housing and the two end faces a gas-tight sealed so that the anode compartment is completely separated from the cathode space. In the case of a polymer membrane fuel cell or -Elektrolysezelle to ensure elastic polymeric encapsulants offer, which enter into a tight connection with the diaphragm, the downstream passageway or zuleitern and the housing. Such elastic polymeric encapsulants are known to one skilled in the art.

The inventive arrangement allows a flexible flow guidance of the electrodes fluids. The supply and discharge of the electrode fluids can take place either via the lateral openings or pocket by the end faces.

To improve the electrical contact between the individual cells, the spacers or flow guides can be resiliently constructed or designed. Then, during assembly of the housing onto the accordion folding a lateral compressive force is applied, which ensures on the electrolyte layer for a permanent contact pressure of the electrodes. In contrast to the lateral pressure force in assembling a conventional parallel plate stack, with both a sufficient sealing pressure like a good contact must be achieved, the lateral compressive force is used here only for better contact. So that they can be specifically adjusted and induces no lateral tension of the electrolyte layer.

The temperature of the cell assembly can be effected inserted into the pockets tempering, which are flowed through by a heat carrier. Alternatively, the downstream passageway or feed line so formed and passed over the end faces and the side pockets inside can be at smaller arrangements is that a kind of fin cooling from the outside takes place.

Furthermore it is also possible according to the invention that the individual cells are connected differently by an external switching means. This may be advantageous when, for example, is to be adjusted are the voltage and the current strength for a particular system and / or when a cell exhibits too niedri- ge power when, for example, the electrode catalyst that cell is damaged.

Subsequently, several embodiments of the electrochemical cell assembly according to the invention the example of a polymer electrolyte are (PEM) fuel cell described without being limited thereto. The examples can be personalized with the necessary modifications as known to one skilled in the art applied to other types of fuel cells and electrolysis cells.

Show it:

Fig. 1 shows a conventional cell stack in a parallel plate configuration, Fig. 2 shows a conventional planar cell arrangement according to the principle of the strip membrane,

Fig. 3 shows a conventional planar cell array with a continuous electrolyte layer 20,

Fig. 4 is a planar cell array with overlap of ziegeiförmiger Bipolarrahmen 9,

Fig. 5 is a perspective view of the folded electrolyte layer of a cell stack 10 according to the invention,

Fig. 6 shows a cross section through a cell stack 10 along AB according to FIG. 5, FIG. 7 is a side view of the active electrode surface 38 of a folding bag 12 according to Fig. 5 for the flow configuration according to claim 10, Fig. 8 is a side view of the active electrode surface 38 . a folding bag 12 according to Fig 5 for the flow configuration according to claim 11, and the section along GH,

Fig. 9 is a side view of the active electrode surface 38 of a folding pocket 12 in FIG. 5 for the flow configuration according to claim 12, and a cross section taken along CD,

Fig. 10 is a sectional view of a PEM fuel cell according to claim 13 and 14 with cooling fins 52 and integrated humidification 46, in which only the cathode side is shown in detail, Fig. 11 is a longitudinal section through the anode side of a direct methanol fuel cell according to claim 15,

Fig. 12 is a section through a membrane fuel cell, constructed in accordance with claim 2 by two mutually gas-tightly connected to the membrane folds, so that the anode chamber 14 completely from the membrane 20 (and the two end plates 48) is enclosed,

Fig. 13 is a section through a membrane fuel cell, in which the folding pockets 12 are arranged according to claim 3 by a cylindrical core, FIG. 14, made up of five series-connected single cells with an inventive PEM fuel cell stack, measured current-voltage - characteristic, and Figure 15, which belongs to Figure 14 power curve of the PEM fuel cell stack...

Figures 1 to 4 have already been explained in the introductory part of the description of the prior art.

Fig. 5 shows the scheme of the folded electrolyte layer of a cell stack 10 of the invention using the example of a PEM fuel cell or a PEM electrolysis cell. The electrolyte layer 20 is formed as a polymer electrolyte membrane and maanderformig folded. The resulting single folding pockets 12 are respectively opened to the anode compartment 14 and cathode compartment sixteenth the folding pockets 12 are sealed against each other and to the outside by a sealing compound 18 on the two end faces 19th

Fig. 6 shows a cross section through a cell stack 10 of FIG. 5 along AB, in which the individual components can be identified within the folding pockets 12 in detail. Within the folding pockets are located on both sides of the electrolyte layer 20 each an electrode catalyst layer 22 with electrode backing 24. The electrolyte membrane forms together with the two electrode catalysts and the backing the so-called membrane electrode assembly (MEA) 26. FEMER are between the two halves EME present within a folding bag 12 is electrically conductive, wave-shaped profiled elements 30 which serve for the distribution and management of the electrodes fluids (flow fields). They may be formed from a suitable metal sheet. The elements 30 form for the EMEs 26 simultaneously initiating the downstream or feed line 34 or associated with these electrically conductive connection. The profiled elements 30 may be placed in protective frame 28 made of a suitable electrically non-conductive plastic, to protect the membrane fold. is addition to the protection of the electrolyte layer 20 from mechanical damage at the base of each folding pocket 12, this protective frame 28 may serve the flow guide within the folding pockets, as described below in Fig. 7 explained.

For a series connection of individual cells or initiating the downstream must be duplicated within a folding pocket 12 and feed line insulated from each other 34th This is done in Fig. 6 by means disposed between the two downstream passageway or zuleitern electrical insulation 36. The electrical series connection of the individual cells on the downstream passageway or feed line 34 is indicated in Fig. 6. The electrical connection preferably takes place over the end surfaces 19, for example, embedded in the casting compound 18th

The fold assembly of FIG. 6 is surrounded by the outer casing, indicated 48, 49. When assembling a compressive force in the direction of arrows 50 may be applied on the housing side parts 49, through which the wave-shaped profiled elements are biased 30th Thus, the catalyst layers 22, the electrode backing 24, the electrolyte layers 20 and initiating the downstream or permanently pressed against each other feeders 34, which may result in a improved contact to improved cell behavior.

In Fig. 7 to 9 show various flow guides according to the invention for the electrode fluids are shown. In Fig. 7, the electrode fluid over the incorporated in the protection frame 28 feed channels 40 from the open side is supplied to the folding pockets, flows within the folding pockets in the direction of the end faces 19 and is peeled off laterally by the incorporated into the protective frame 28 discharge channels 42. The flow guide elements 30 are profiled so that they support the vertical flow guidance here. In FIG. 8, the electrode fluid is supplied over a certain height of the folding pockets laterally, horizontal flows (parallel to the end surfaces 19) through the folding pockets 12, at the base of each folding pocket is provided with a porous or with lateral openings collecting channel received and deflected 44 and flows back outside the Zuströmungsbereichs. The flow guide members 30 are profiled such that they support the horizontal flow. In this case, the collecting channel 44 protects the folding of the electrolyte layer 20 at the base of each folding pocket 12 from mechanical damage by the elements 30. The collection channel 44 may be connected to the frame 28, which supports the flow guidance and redirection. In addition to the illustrated central unit with two outlets various combinations with single or multiple inlets and outlets as well as a meandering shaped (several times varying between inlet and outflow) flow profile are possible, of course.

In Fig. 9, the electrode fluid over the entire height of the folding pockets 12 flows parallel to the end surfaces 19, at the base of each folding pocket is absorbed through a collection channel 44 12 and guided in the collecting channel 44 by one of the molded end surfaces 19 to the outside. In a similar manner, the anode fluid can be supplied by corresponding flow channels on the other end face and is discharged from the pockets in each case laterally through flow channels 44 on the one end face, the cathode fluid. Of course, all of the flow guides of Fig. 7 can be combined to 9 for the anode fluid with all flow guides for the cathode fluid, wherein the flow directions may also be changed.

In case of a membrane fuel cell with hydrogen-air operation has as its object, the electrodes gases, but at least the air to moisten so that the membrane does not dry out. This requires an adjustment of the saturation temperature of the humidifier to the (average) temperature of the membrane fuel cell. In addition, the temperature of the fuel cell should be limited by a sufficient heat dissipation. In the folding arrangement of FIG. 5, the standard solution of heat removal is to introduce into the folding pockets heat dissipation elements, which are flowed through by a heat carrier. The heat dissipation elements are appropriately integrated into the profiled power dissipation elements 30th The supply and discharge of the heat carrier can be carried out in each case on the side-opened bags or by the end faces 19th

For small units, heat dissipation can also be achieved by cooling fins. An embodiment according to the invention for membrane fuel cells with water serstoff-air mode is shown in FIG. 10. In this case, only the air side is shown in detail. The elements 13 of the hydrogen side can eg. Example, have a structure as shown in Fig. 6. On the air side, the profiled elements 30 are preferably formed of a highly thermally conductive material and extended so that they protrude as cooling fins 52 laterally out of the opened Falttaschen12. Alternatively, a separate, highly thermally conductive fin can be electrically isolated between the two profiled elements 30 and pushed the current conductor 34 and guided laterally outwards. The outer part of the cooling fin 52 is then cooled by natural convection or blowing ambient air. A portion of the air is drawn in the manner of Fig. 9 by a fan outside one of the two end faces 19 through the flow channels 44. The air flows via a porous, absorbent, water-wetted structure 46 disposed on and between the cooling fins 52 and thus largely assumes the cooling fin temperature. The porous structure 46 is impregnated in the rule, either periodically with (decalcified) water or is on one side with a water reservoir in communication, so that the water is distributed by capillary action independently and uniformly over the porous structure. In this way, humidification always takes place with a saturation temperature corresponding approximately to the cell temperature and thus ensures sufficient membrane humidification. Simultaneously, the heat of evaporation of the dampening water is used for cooling the cell.

In the case of a direct methanol fuel cell with liquid methanol-water mixture for fuel to an inventive construction offers in FIG. 11 to where the fold is arranged horizontally and have the openings of the folding pockets on the (fluid-filled) anode side up. The methanol-water mixture is then R mpe of a Umwälzpu or by Bla senauftriebsströmung passed through the cell in the circuit to discharge the CO 2 formed as well as the heat released. It can be made of the flow of the methanol-water mixture through collecting channels 44 on one (or both) end face (s). It then flows into the folding pockets from bottom to top, wherein the CO 2 bubbles formed entrains.

Besides those shown in Figs. 5 to 10 arrays closed by a housing electrode spaces one electrode chamber can also be completely enclosed by the membrane. FIGS. 12 and 13 show two embodiments in cross-section. These arrangements always come to mind when one electrode chamber to communicate with the atmosphere in contact 16th Typical examples are air-breathing fuel cell with small hydrogen or methanol as fuel, and electrolytic cells for the production of hydrogen (from water), chlorine (from aqueous HCI) or oxygen (from water). When the cathode are in contact in the last two cases, with the environment, the reduction of H + with atmospheric oxygen to water is carried out. In Fig. 12, two folds are gas-tightly connected to each other by the example of hydrogen or direct methanol fuel cell, the cathode chamber 16 is open to the environment and the anode compartment 14 of the electrolyte membrane 20 and the two end plates is fully enclosed. It may be appropriate, in each case only to be arranged in the folding pockets of the anode chamber 14, an electrically conductive profiled element 30th Then, the two outer counter-electrodes must be electrically connected in the folding pockets open to the surrounding cathode compartment 16 by contact bridges 55 to form an electrode-membrane unit (EME) 26th The required contact pressure can again be effected via end plates 49, which are pressed together by a force 50th

Alternatively, the convolution shown in FIG. 13 may be arranged around a cylindrical core around also so that the folding pockets 12 star-shaped extending from the core, and 14 is opened inward toward the cylindrical core and the other electrode chamber 16 to the outside, an electrode space. In the arrangement of Fig. 13 gas permeable cathode are angled 53 is inserted in the cathode pockets 16, that the necessary pressing force to membrane 20, catalyst layers 22 and electrode backing 24 yields when these cathodes are pressed together by clamping strands 54. Alternatively, such an arrangement may be enclosed by a cylindrical casing. This is useful, for example, then on when the fuel or electrolysis cell is to be operated under pressure.

Fig. 14 shows the measured data of a current-voltage characteristic of a cell stack according to the invention, made up of five series-connected single cells. Fig. 15 shows the corresponding performance curve. The electrolyte layer is formed by a continuous Nafion® 1135 membrane. The electrodes are Double Sided ELAT electrodes from E-TEK, each with a Pt loading of anode and cathode sides of 0.4 mg Pt / cm 2. These electrodes contain the same catalyst layer and backing. The electrode area is 40 cm 2 per cell. The gases hydrogen and air were humidified and externally supplied at a pressure of 250 mbar. It has been chosen a flow guide according to Fig. 7. When potting proved a additionsvemetzender, transparent, two-component silicone rubber as well suited. He also has at room temperature on a variety of substrates, in particular Nafion membranes, a very good adhesion. To improve the adhesion to the polycarbonate housing as well as on metal surfaces, a coupling agent or a primer containing reactive silanes or silicone resins used.

LIST OF REFERENCE NUMBERS

4 holes for tie rods

6 bipolar plate flow fields

7 endplate

8 gas seal Bipolarrahmen

cell stack

Folding

Contents of a folding pocket

anode chamber

cathode space

sealing compound

face

Electrolyte layer (electrolyte membrane)

catalyst layer

Electrode Backing

Membrane electrode unit (EME)

protective frame

Profiled elements (flow fields)

Electrode fluid channels

Downstream passageway or feeders

electrical insulation

electrode area

feed channel

discharge channel

collecting duct

Absorbent porous structure

outer casing

Outer-side part

Direction of an external compressive force upon assembly of the housing

Cooling fin angular electrode

strap

Contact bridge

Claims

claims
1. An electrochemical cell, in particular PEM fuel cell or electrolysis cell, with a fixed, gas-tight, containing electrolyte layer (20) as a membrane in a housing (48, 49) is maanderformig folded or so piecewise gas-tightly connected to one another either that meandering folding pockets (12 ) are formed, said folding pockets (12) at their end faces (19) against the neighboring pockets and / or the housing are sealed, so that the entire pocket space on one side of the fold ( "anode chamber") (14) from the entire pocket space the other side of the fold ( "cathode compartment") (16) is isolated and all folding pockets of the anode space from an anode fluid and all folding pockets of the cathode compartment from a cathode fluid flow through separately or flows over and the electrolyte layer (20) on both sides of the gusset electrode catalyst (22), backing (24) flow, field (30) and downstream passageway or zuleitern (34) is provided, so that ei ne series of membrane electrode units (EMEs) (26) is formed, and initiating the downstream or feeders (34) are each electrically connected so EME with the downstream passageway or zuleitern adjacent EMEs that an electrical parallel or series connection of individual EMEs is generated.
2. An electrochemical cell according to claim 1, wherein a gas-tightly enclosed by the membrane-electrode space is formed in that the or is gas-tightly connected to one end of the pleated membrane to the other end of the pleated membrane that a plurality of membrane folds are connected at their ends gas-tight manner.
3. An electrochemical cell according to claim 1 or 2, wherein the folding is arranged around a cylindrical core, that the folding pockets (12) protrude star-shaped from the core, and one electrode chamber (14) inward to the cylindrical core and the other electrode chamber (16) is open to the outside and, optionally, an outer housing (48) encloses the folding assembly cylinder.
4. An electrochemical cell according to any one of claims 1 to 3, wherein the electrode chambers at the end faces (19) of the folding arrangement, and optionally the common housing by potting material (18) are sealed gas-tight, wherein as embedding an elastically curable polymer composition, a ceramic composition or lot is used, and the adhesion of the casting compound to the sealed elements are optionally ensured by a primer or an adhesion promoter or improved.
5. An electrochemical cell according to any one of claims 1 to 4, wherein the EMEs (26) are electrically connected in series, for which purpose the downstream passageway or feed line (34) of the two EME halves in each folding pocket (12) are electrically insulated from each other and their electrical connections by the potting compound (18) are either at the end faces (19) or through the lateral opening of the folding pockets outward and connected there to the terminals of the Stromabbzw, feeders (34) of the adjacent bags.
6. An electrochemical cell according to any one of claims 1 to 5, wherein the downstream passageway or feed line (34) are profiled or composed of several elements that they form flow channels (32) for the directed flow through the folding pockets (12).
7. An electrochemical cell according to any one of claims 1 to 6, wherein in the folding pockets (12) elements for the purpose of directed flow guide (flow field, (30)) and / or for electrical supply and downstream passageway (34) are installed, the deform elastically to lateral pressure as soon as the housing (49) exerting a lateral pressure force (50) on all the folding pockets (12), so that the impressed spring tension of these elements for a permanently good mechanical contact between the electrolyte layer (20), catalyst layer ( 22), backing (24) and downstream passageway or zuleitern (34) provides.
8. An electrochemical cell according to any one of claims 1 to 7, wherein at predetermined folding pockets (12) devices for heat dissipation or are arranged feed, which are flowed through by a heat transfer fluid, said supply and discharge of heat transfer fluid through lines through the potted end faces ( 19) or is carried out through the side pocket openings.
9. An electrochemical cell according to any one of claims 1 to 8, wherein designed for heat dissipation initiating the downstream or feed line (34) or more lying in the folding pockets surfaces as cooling fins (52) and through the molded end faces (19) or the side pocket openings by be guided outside.
10. An electrochemical cell according to any one of claims 1 to 9, wherein the anode fluid and / or the cathode fluid via supply passages (40) is fed into the side pocket openings, within the folding pockets (12) in the direction of the end faces (19) is guided by discharge channels (42) is withdrawn in the side pocket openings.
11. An electrochemical cell according to any one of claims 1 to 9, wherein said cathode fluid and / or the anode fluid to the end faces parallel (19) through the folding pockets (12) is guided, wherein the base of each folding pocket a collecting channel (44) receiving the electrode fluid or and the distributed electrode fluid flows over a certain height of the folding pockets (12) in these, from the collecting channel (44) is taken up and deflected and flows back over a certain height of the folding pockets.
12. An electrochemical cell according to any one of claims 1 to 9, wherein said cathode fluid and / or the anode fluid over the entire height of the folding pockets (12) parallel to the end surfaces (19) through the folding pockets (12) is guided (by a collecting channel 44 ) is added to each folding pocket at the bottom or distributed, wherein the collecting channel (44) is passed through one or both of the potted end faces (19) and all the collecting channels have their common inlet and outlet in a connection head outside the potted end faces (19) ,
13. Polymer membrane fuel cell according to claim 11 or 12, characterized in that the air and optionally also the combustion gas, respectively on an absorbent, porous structure (46) is placed on the folding pockets (12) pressed into this folding pockets or vacuumed and is moistened and thereby the absorbent porous structure (46) is either soaked periodically with water or is on a side in contact with water, so that the water is distributed by capillary action independently and uniformly over the porous structure (46).
14. Polymer membrane fuel cell according to claim 9 and 13, characterized in that the porous structure (46) on or between the protruding out of the pockets of the cathode side cooling fins is arranged (52) so that the humidification of the air is approximately at the temperature of fins takes place.
15. Direct methanol fuel cell according to any one of claims 1 to 12, wherein the anode chamber (14) is filled with the liquid methanol-water mixture and the carbon dioxide bubbles formed during the anode reaction by forced or natural convection with the methanol-water mixture of the be transported anode bags (12).
EP20040804231 2003-12-23 2004-12-22 Electrochemical cell arrangement having a pocket-shaped structure Withdrawn EP1706914A2 (en)

Priority Applications (2)

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DE10361468 2003-12-23
PCT/EP2004/014637 WO2005064731A3 (en) 2003-12-23 2004-12-22 Electrochemical cell arrangement having a pocket-shaped structure

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DE102007050617A1 (en) * 2007-10-23 2009-04-30 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Fuel cell system with in-shingle design fuel cells and uses
GB201314769D0 (en) * 2013-08-19 2013-10-02 Intelligent Energy Ltd A fuel cell and its method of manufacture
DE102016117984A1 (en) 2016-09-23 2018-03-29 Kuntze Instruments Gmbh A method for attaching at least two electrodes on an electrochemical measuring cell for determining the concentration of an oxidizing or reducing agent or the conductivity and other measured quantities in a liquid or at the surface of materials such as paper, non-woven, food or skin and mucosa
DE102016122285A1 (en) * 2016-11-19 2018-05-24 Friedrich-Schiller-Universität Jena Flow battery for storing electrical energy with radially disposed hollow fiber membranes

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JPH1030197A (en) * 1996-05-15 1998-02-03 Mitsubishi Electric Corp Solid-state high-polymer electrolytic module and its production, and dehumidifying device using the same
US6054228A (en) * 1996-06-06 2000-04-25 Lynntech, Inc. Fuel cell system for low pressure operation
KR100409042B1 (en) * 2001-02-24 2003-12-11 (주)퓨얼셀 파워 Membrane Electrode Assembly and method for producing the same
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