EP1706914A2 - Ensemble cellules electrochimiques a structure en forme de poches - Google Patents

Ensemble cellules electrochimiques a structure en forme de poches

Info

Publication number
EP1706914A2
EP1706914A2 EP04804231A EP04804231A EP1706914A2 EP 1706914 A2 EP1706914 A2 EP 1706914A2 EP 04804231 A EP04804231 A EP 04804231A EP 04804231 A EP04804231 A EP 04804231A EP 1706914 A2 EP1706914 A2 EP 1706914A2
Authority
EP
European Patent Office
Prior art keywords
pockets
folding
anode
fluid
cell according
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Withdrawn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
EP04804231A
Other languages
German (de)
English (en)
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.)
Universitaet Stuttgart
Original Assignee
Universitaet Stuttgart
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
Application filed by Universitaet Stuttgart filed Critical Universitaet Stuttgart
Publication of EP1706914A2 publication Critical patent/EP1706914A2/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/1009—Fuel cells with solid electrolytes with one of the reactants being liquid, solid or liquid-charged
    • H01M8/1011—Direct alcohol fuel cells [DAFC], e.g. direct methanol fuel cells [DMFC]
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/02—Details
    • H01M8/0271—Sealing or supporting means around electrodes, matrices or membranes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/1007—Fuel cells with solid electrolytes with both reactants being gaseous or vaporised
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
    • H01M8/1018—Polymeric electrolyte materials
    • H01M8/1065—Polymeric electrolyte materials characterised by the form, e.g. perforated or wave-shaped
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/24—Grouping of fuel cells, e.g. stacking of fuel cells
    • H01M8/241—Grouping of fuel cells, e.g. stacking of fuel cells with solid or matrix-supported electrolytes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04007—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids related to heat exchange
    • Y—GENERAL 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
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells

Definitions

  • the invention relates to an electrochemical cell stack, preferably a cell stack for membrane fuel or membrane electrolysis cells, formed from a plurality of individual cells connected in parallel or in series, all cathode sides of the individual cells and all anode sides of the individual cells being arranged in pockets, which are arranged by an accordion-shaped or formed in a meandering folded electrolyte layer and which are closed on their upper and lower end faces.
  • the individual cells are constructed in a known manner from electrodes with current or supply leads and, if appropriate, backing and flow distributors on both sides of the electrolyte layer, the individual current or supply leads being electrically connected in such a way that a series or parallel connection results.
  • the invention thus relates to a novel structure of an electrochemical cell stack which, in comparison to the conventional structure based on the principle of a parallel plate stack, is characterized in particular by simple, common access to all anode and cathode spaces, a simplified sealing and by a lower mechanical stress load and one characterized by lower land consumption of the electrolyte material.
  • electrochemical reactions take place at the electrodes by electron supply or removal, in which either electrical energy is consumed or generated.
  • individual cells are expediently electrically connected in series so that the required or generated electrical voltage is a multiple of the individual cell voltage.
  • the cells connected in series are expediently arranged in the form of a compact cell stack (“stack”).
  • the cell stack 10 comprises a multiplicity of repetition units, each comprising a bipolar plate 6, two seals 8 and the membrane electrolyte layer 20 with the electrodes 38 coated on both sides and coated with catalyst. End plates 7 are provided at both ends, in which the bores 4 are provided for guiding the tie rods. The plate stack is assembled with these tie rods. volume-tensioned to apply the necessary sealing forces for the flat seals 8. By compressing the (elastic) seals 8, stresses can be induced in the electrolyte membranes 20, which in the long run lead to cracks.
  • the channels 32 serve to supply and discharge the electrode fluids and, if appropriate, coolant and to distribute the electrode fluids to the electrode spaces on both sides of the electrolyte membrane 20. They penetrate the electrolyte membranes 20 and thus reduce their effective area to the electrode surface 38.
  • a fuel cell is known from US 2003 / 0108783A1, in which, based on the conventional parallel plate design, the electrolyte layer edges are folded in the form of flaps so that they facilitate the sealing of the electrodes or the separation of the two electrode fluids. This should eliminate the flat seals on both sides of the electrolyte layer. However, this increases the risk that the electrolyte layer will tear open at the folded corners and pressed by the tie rods. In addition, the area consumption of electrolyte membrane material increases due to the folding.
  • planar cell concepts take a different approach, in which a continuous separating layer separates the entire anode and the entire cathode space.
  • Such an electrochemical cell is known from DE 43 29 819 A1, which is designed in the form of a strip membrane. 2 shows the functional principle for the case of the polymer electrolyte membrane (PEM) fuel cell.
  • the strip membrane consists of successive electrolyte layer elements, with electrodes 38 applied to both sides of the electrolyte layer 20, as well as contact elements 34 and insulating elements 36.
  • Anode elements 14 and cathode space 16 are located on opposite sides of the strip membrane and must be sealed to the outside and against each other.
  • DE 43 29 819 A1 also describes a step-like arrangement for connecting the individual cells in series. This eliminates the contact and insulating elements and the electrodes 38 take over the function of the current collector or conductor.
  • FIG. 3 A continuous electrolyte layer 20 is used in this arrangement.
  • the electrodes 38 are applied locally one behind the other on both sides of the electrolyte layer 20 and electrically separated from one another and connected to one another via the edges by means of current collectors or feeders 34.
  • the entire electrode surface 38 is contacted by current collector plates.
  • the anode fluid then flows on one side, the cathode fluid on the other side of the flat electrolyte layer 20 and must be sealed off from the outside and from the other electrode fluid.
  • a (membrane) fuel cell system which is based on a modified planar arrangement.
  • the electrolyte layer is not continuous.
  • the planar arrangement consists of a sequence of (metallic) bipolar frames 9, which are arranged overlapping in the manner of roof tiles and between which there are separate electrolyte layers 20, as shown in FIG. 4.
  • the anode compartment 14 is always on one side, the cathode compartment 16 on the back of the arrangement.
  • So-called gas barriers, a kind of flat seals 8 are used to separate the two electrode fluid spaces. integrated in the electrodes 38 on the sides to be sealed off from one another.
  • the planar arrangement can also be folded once and sealed at the side.
  • the present invention is therefore based on the object of providing an electrochemical cell arrangement in which, in contrast to the conventional parallel plate stack concepts, as shown in FIG. 1, the cells are sealed without the application of a sealing force and the electrolyte layer surface used is better utilized. Furthermore, in contrast to the planar arrangements, as shown in FIGS. 2 to 4, a compact volume without a large footprint is to be achieved. In contrast to the roof-tile structure with stacked pockets, as shown in FIG. 4, a simpler structure with fewer sealing surfaces and simple flow guidance is also to be achieved.
  • an electrochemical cell in particular a PEM fuel cell or electrolysis cell, which is characterized in that a solid, gas-tight, electrolyte-containing layer (20) (“membrane”) in a housing (48, 49) is either meandering folded or so gas-tightly connected piece by piece that meandering folding pockets (12) are formed, that these folding pockets (12) are sealed at their end faces (19) against the neighboring pockets and / or the housing, so that the entire pocket space is on one side the folding ("anode compartment") (14) of the entire pocket space of the other side of the fold (“cathode compartment") (16) is separated and all the folding pockets of the anode compartment are flowed through or overflowed by an anode fluid and all the folding pockets of the cathode compartment are separated from one another and the electrolyte layer (20) on both sides of the Folding pockets are provided in the usual way with electrode catalyst (22), backing (24), flow field (30) and current conductors (34) so that a sequence
  • an electrode space enclosed by the membrane in a gas-tight manner is formed in that one end of the folded membrane is connected in a gas-tight manner to the other end of the folded membrane or in that a plurality of membrane folds are connected to one another in a gas-tight manner at their ends.
  • the fold is arranged around a cylindrical core in such a way that the folding pockets (12) protrude in a star shape from the core and one electrode space (14) inwards to the cylindrical core and the other electrode space (16) is open on the outside and optionally an outer housing (48) encloses the folding arrangement in a cylindrical shape.
  • the electrode spaces on the end faces (19) of the folding arrangement and, if appropriate, on the common housing are sealed gas-tight by casting compound (18), the sealing compound being, for example, an elastically curable polymer compound, in particular an elastically hardenable silicon-containing polymer compound, a ceramic compound or a solder is used and the adhesion of the sealing compound to the elements to be sealed is ensured or improved if necessary by pretreatment (primer, adhesion promoter, etc.).
  • the sealing compound being, for example, an elastically curable polymer compound, in particular an elastically hardenable silicon-containing polymer compound, a ceramic compound or a solder is used and the adhesion of the sealing compound to the elements to be sealed is ensured or improved if necessary by pretreatment (primer, adhesion promoter, etc.).
  • the EMEs (26) are electrically connected in series, for which purpose the current conductors (34) of the Both EME halves in each folding pocket (12) are electrically insulated from each other and their electrical connections are led either to the outside through the potting compound (18) on the end faces (19) or through the side opening of the folding pockets and there with the connections of the current supply or can be connected to the feeder (34) of the adjacent pockets.
  • the current conductors or feeders (34) are preferably profiled or composed of several elements in such a way that they form flow channels (32) for the directional flow through the folding pockets (12).
  • Elements for the purpose of directed flow guidance (flow field, (30)) and / or for electrical current supply or supply (34) can be installed in the folding pockets (12), which deform elastically to lateral pressure as soon as the housing ( 49) a lateral compressive force (50) is exerted on all folding pockets (12), so that the impressed spring tension of these elements leads to permanent good mechanical contact between the electrolyte layer (20), catalyst layer (22), backing (24) and current drain ( 34) provides.
  • devices for heat removal or supply can be arranged in predetermined folding pockets (12) through which a heat transfer fluid flows, the supply and removal of the heat transfer fluid taking place via lines through the cast end faces (19) or through the side pocket openings.
  • heat dissipation can be provided in that the current conductors or supply lines (34) or further surfaces lying in the folding pockets are designed as cooling ribs (52) and are guided to the outside through the encapsulated end surfaces (19) or the lateral pocket openings.
  • the anode fluid and / or the cathode fluid can also be supplied via supply channels (40) in the side pocket openings, flow inside the folding pockets (12) in the direction of the end faces (19) and be drawn off through discharge channels (42) in the side pocket openings.
  • the cathode fluid and / or the anode fluid can flow through the folding pockets (12) parallel to the end faces (19), a collecting channel (44) receiving or distributing the electrode fluid at the bottom of each folding pocket and the electrode fluid over a certain height of the folding pockets (12) flows into the latter, is received and deflected by the collecting duct (44) and flows back again over a certain height of the folding pockets.
  • ode fluid can also flow through the folding pockets (12) over the entire height of the folding pockets (12) parallel to the end faces (19) and can be received or distributed by a collecting channel (44) at the bottom of each folding pocket, the collecting channel (44) is guided through one or both of the encapsulated end faces (19) and all the collecting channels have their common inlet or outlet in a connection head outside the encapsulated end faces (19).
  • Another object of the present invention is a polymer membrane fuel cell, which is designed in such a way that the air and possibly also the fuel gas are pressed into these folding pockets via an absorbent, porous structure (46) which is placed on the folding pockets (12) or is sucked and thereby moistened and the absorbent porous structure (46) is either periodically impregnated with water or is in contact with water on one side so that the water is distributed independently and evenly over the porous structure (46) by capillary action.
  • the porous structure (46) can preferably be arranged on or between the cooling fins (52) protruding from the pockets on the cathode side in such a way that the humidification of the air takes place approximately at 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 space (14) is filled with the liquid methanol-water mixture and the carbon dioxide bubbles formed in the anode reaction by forced or natural convection with the methanol Water mixture can be transported from the anode pockets (12).
  • the electrochemical cell arrangement according to the invention is based on a planar arrangement according to FIG. 3.
  • the electrolyte layer provided in the context of the present invention is folded in a meandering manner between the individual electrodes, so that folding pockets are formed. These folding pockets are sealed at their end faces against the adjacent pockets and the housing such that the entire pocket space on one side of the fold (“anode space”) is separated from the entire pocket space on the other side of the fold (“cathode space”). All pockets of the anode or cathode spaces are separated from the anode or cathode fluid and flowed through parallel to each other.
  • the electrolyte layer is provided on both sides of the folding pockets in a known manner with an electrode catalytic converter and a current discharge or supply line and, if appropriate, backing and flow guidance (“flow field”).
  • an electrode catalytic converter and a current discharge or supply line and, if appropriate, backing and flow guidance (“flow field”).
  • flow field In the case of membrane fuel cells, this results in a sequence of electrode-membrane-electrode units (EMEs)
  • EMEs electrode-membrane-electrode units
  • the current conductors or feeders in the folding pockets can be led out and electrically connected to one another in such a way that the individual cells formed between two folding pockets are connected in parallel or in series, as required To be carried out twice in each pocket and electrically insulated from each other, this creates a compact design with high power density.
  • the folding pockets are arranged in a housing, so that two spaces which are sealed off from one another in a gas-tight manner are formed in the housing.
  • the housing then usually has corresponding feeds for both electrode fluids on the respective sides.
  • the meandering folding of the electrolyte layer according to the invention is suitable for flexible electrolyte layers, in particular for polymeric electrolyte membranes.
  • a comparable pocket structure can be achieved by connecting the flat electrolyte walls of each pocket to one or three sides in a gas-tight manner.
  • a connection interrupting the ion current has the additional advantage of reliably preventing cross currents (ion currents through the electrolyte) between the individual cells.
  • the anode or cathode fluid is generally distributed in parallel to all anode or cathode pockets.
  • the flow guidance within the respective pockets can be facilitated by spacers and flow fields arranged between the electrodes and current collectors or feeders. These elements can also be combined in one component, for example by profiling the current arrester or feeder.
  • the folding arrangement is made by one Enclosed housing and sealed gas-tight on the two end faces so that the anode compartment is completely separated from the cathode compartment.
  • elastic polymer casting compounds are suitable for this, which form a gas-tight connection with the membrane, the current conductors or conductors and the housing. Such elastic polymer casting compounds are known to a person skilled in the art.
  • the arrangement according to the invention allows flexible flow guidance of the electrode fluids.
  • the electrode fluids can be supplied or discharged either through the side pocket openings or through the end faces.
  • the spacers or flow guides can be constructed or designed to be resilient. Then, when assembling the housing, a lateral compressive force is exerted on the concertina fold, which ensures that the electrodes are permanently pressed onto the electrolyte layer. In contrast to the lateral compressive force when assembling a conventional parallel plate stack, with which both sufficient sealing pressure and good contact must be achieved, the lateral compressive force only serves for better contact. It can be adjusted in a targeted manner and does not induce any lateral tensile stress on the electrolyte layer.
  • the temperature of the cell arrangement can be brought about by means of temperature control elements inserted into the pockets, through which a heat transfer medium flows.
  • the current conductors or feeders can be designed and guided to the outside via the end faces or the lateral pockets in such a way that a type of rib cooling takes place from the outside.
  • the individual cells are connected differently by an external switching device. This can be advantageous if, for example, the voltage or the current intensity is to be adapted for a specific system and / or if a cell has an excessively low Performance shows if, for example, the electrode catalyst of that cell is damaged.
  • FIG. 1 shows a conventional cell stack in a parallel plate arrangement
  • FIG. 2 shows a conventional planar cell arrangement based on the principle of the strip membrane
  • FIG. 5 shows 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 shows a side view of the active electrode surface 38 of a folding pocket 12 according to FIG. 5 for the flow configuration according to claim 10
  • FIG. 8 shows a side view of the active electrode surface 38 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 according to FIG. 5 for the flow configuration according to claim 12, and a cross section along C-D,
  • 10 shows a section through a PEM fuel cell according to claims 13 and 14 with cooling fins 52 and integrated air humidification 46, in which only the cathode side is drawn in detail, 11 shows a longitudinal section through the anode side of a direct methanol fuel cell according to claim 15,
  • FIG. 12 shows a section through a membrane fuel cell which, according to claim 2, is constructed by two membrane folds connected to one another in a gastight manner, so that the anode space 14 is completely enclosed by the membrane 20 (and the two end plates 48),
  • FIG. 13 shows a section through a membrane fuel cell in which the folding pockets 12 are arranged around a cylindrical core
  • FIG. 14 shows the current-voltage measured with a PEM fuel cell stack according to the invention, constructed from five individual cells connected in series - Characteristic curve
  • FIG. 15 shows the power curve of the PEM fuel cell stack belonging to FIG. 14.
  • FIG. 5 shows the schematic of the folded electrolyte layer of a cell stack 10 according to the invention using the example of a PEM fuel cell or a PEM electrolysis cell.
  • the electrolyte layer 20 is designed as a polymer electrolyte membrane and folded in a meandering shape.
  • the resulting individual folding pockets 12 are each open to the anode compartment 14 or cathode compartment 16. On the two end faces 19, the folding pockets 12 are sealed against one another and to the outside by a casting compound 18.
  • FIG. 6 shows a cross section through a cell stack 10 according to FIG. 5 along AB, in which the individual components within the folding pockets 12 can be seen in detail.
  • an electrode catalyst layer 22 Inside the folding pockets there is an electrode catalyst layer 22 with an electrode backing 24 on both sides of the electrolyte layer 20.
  • the electrolyte membrane forms, together with the two electrode catalysts and the backing, the so-called electrode membrane unit (EME) 26 between the two EME halves there are electrically conductive, wavy profiled elements 30 within a folding pocket 12, which serve to distribute and guide the electrode fluids (flow fields). You can be formed from a suitable metal sheet.
  • the elements 30 simultaneously form the current conductors 34 or have an electrically conductive connection with them.
  • the profiled elements 30 can be inserted into protective frames 28 made of a suitable, electrically non-conductive plastic in order to protect the membrane fold.
  • these protective frames 28 can serve to guide the flow within the folding pockets, as will be explained below in FIG. 7.
  • the current conductors or feeders 34 For a series connection of the individual cells, the current conductors or feeders 34 must be present twice in a folding pocket 12 and insulated from one another. This is done in FIG. 6 by means of electrical insulation 36 arranged between the two current conductors or conductors.
  • the electrical connection in series of the individual cells via the current conductors or conductors 34 is indicated in FIG. 6.
  • the electrical connection preferably takes place via the end faces 19, e.g. embedded in the casting compound 18.
  • FIG. 7 to 9 show various flow guides according to the invention for the electrode fluids.
  • the electrode fluid is fed from the open side to the folding pockets via the feed channels 40 incorporated into the protective frame 28, flows within the folding pockets in the direction of the end faces 19 and is laterally drawn off again through the discharge channels 42 incorporated into the protective frame 28.
  • the flow guide elements 30 are profiled in such a way that they support the vertical flow guide here.
  • the electrode fluid is supplied laterally over a certain height of the folding pockets, flows horizontally (parallel to the end faces 19) through the folding pockets 12, is received at the bottom of each folding pocket via a porous or side channel 44 and deflected and flows back outside the inflow area.
  • the flow guide elements 30 are profiled so that they support the horizontal flow.
  • the collecting duct 44 protects the folding of the electrolyte layer 20 at the base of each folding pocket 12 against mechanical damage by the elements 30.
  • the collecting duct 44 can be connected to the frame 28, which supports the flow guidance and deflection.
  • various combinations with single or multiple inlets and outlets as well as a meandering flow pattern are of course also possible.
  • the electrode fluid flows over the entire height of the folding pockets 12 parallel to the end faces 19, is received at the bottom of each folding pocket 12 via a collecting duct 44 and is guided outwards in the collecting duct 44 through one of the encapsulated end surfaces 19.
  • the anode fluid can be supplied through flow channels 44 through one end face, the cathode fluid through corresponding flow channels through the other end face and can be discharged laterally from the pockets.
  • all flow guides of FIGS. 7 to 9 for the anode fluid can be combined with all flow guides for the cathode fluid, the flow directions also being able to be changed.
  • the task is to moisten the electrode gases, or at least the air, so that the membrane does not dry out.
  • This requires adaptation of the humidifier's saturation temperature to the (mean) temperature of the membrane fuel cell.
  • the temperature of the fuel cell should be limited by sufficient heat dissipation. 5
  • the standard solution for heat dissipation is to insert heat dissipation elements into the folding pockets, through which a heat transfer medium flows.
  • the heat dissipation elements are expediently integrated into the profiled current dissipation elements 30.
  • the supply and removal of the heat transfer medium can take place via the laterally open pockets or through the end faces 19.
  • FIG. 10 An embodiment of the invention for membrane fuel cells with hydrogen-air operation is shown in FIG. 10. Only the air side is shown in detail.
  • the elements 13 of the hydrogen side can, for. B. have a structure as in Fig. 6.
  • the profiled elements 30 are expediently formed from a material which is a good heat conductor and are elongated such that they protrude laterally as cooling fins 52 from the open folding pockets 12.
  • a separate, highly heat-conducting cooling fin can be pushed between the two profiled elements 30 or the current conductor 34 in an electrically insulated manner and guided laterally outwards.
  • the outer part of the cooling fin 52 is then cooled by natural convection or by blowing with ambient air. Part of the air is drawn in through the flow channels 44 via a fan outside one of the two end faces 19. The air flows over a porous, absorbent structure 46 moistened with water, which is arranged on and between the cooling fins 52 and thus largely assumes the cooling fin temperature.
  • the porous structure 46 is usually either periodically impregnated with (decalcified) water or is connected on one side to a water reservoir, so that the water is distributed independently and evenly over the porous structure by capillary action. In this way, the air is always humidified at a saturation temperature that corresponds approximately to the cell temperature and thus ensures sufficient membrane humidification. At the same time, the heat of evaporation of the dampening water is used to cool the cell.
  • a construction according to the invention is appropriate Fig. 11, in which the fold is arranged horizontally and the openings of the folding pockets for the (liquid-filled) anode side point upwards.
  • the methanol-water mixture is then circulated through a cell from a circulating pump or through the bubble buoyancy flow in order to dissipate the CO 2 formed and the heat released.
  • the methanol-water mixture can flow in through collecting channels 44 over one (or both) end face (s). It then flows from bottom to top in the folding pockets, taking the CO 2 bubbles formed with it.
  • an electrode space can also be completely enclosed by the membrane. 12 and 13 show two embodiments in cross section. These arrangements are always appropriate when an electrode space 16 is to be in contact with the atmosphere. Typical examples are air-breathing small fuel cells with hydrogen or methanol as fuel, as well as electrolysis cells for the production of hydrogen (from water), chlorine (from aqueous HCl) or oxygen (from water). If the cathodes are in contact with the environment in the last two cases, H + is reduced with atmospheric oxygen to water.
  • the folding according to FIG. 13 can also be arranged around a cylindrical core in such a way that the folding pockets 12 protrude in a star shape from the core, and the one electrode space 14 inwards to the cylindrical core and the other electrode space 16 is open to the outside.
  • gas-permeable cathodes 53 are angled into the cathode pockets 16 in such a way that the necessary pressing force on the membrane 20, catalyst layers 22 and electrode backing 24 results when these cathodes are pressed together by tensioning straps 54.
  • such an arrangement can also be enclosed by a cylindrical housing. This is useful, for example, when the fuel or electrolysis cell is to be operated under excess pressure.
  • FIG. 14 shows the measured data of a current-voltage characteristic curve of a cell stack according to the invention, constructed from five individual cells connected in series.
  • 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 for the anode and cathode side of 0.4 mg Pt / cm 2 . These electrodes contain the catalyst layer and backing at the same time.
  • the electrode area is 40 cm 2 per cell.
  • the gases hydrogen and air were humidified externally and supplied at an overpressure of 250 mbar.
  • a flow guide according to FIG. 7 was chosen.
  • An addition-curing, transparent, two-component silicone rubber has proven to be a suitable casting compound. It has very good adhesion even at room temperature on many substrates, especially on Nafion membranes. In order to improve the adhesion on the polycarbonate housing and on metal surfaces, an adhesion promoter or a primer containing reactive silanes or silicone resins was used.
  • Electrolyte layer (electrolyte membrane)
  • Electrode membrane unit (EME)

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  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Sustainable Development (AREA)
  • Sustainable Energy (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Fuel Cell (AREA)

Abstract

Empilement de cellules électrochimiques, de préférence empilement de cellules à combustible à membrane ou de cellules à électrolyse à membrane, formé de plusieurs cellules individuelles connectées en parallèle ou en série, tous les côtés cathode des cellules individuelles et tous les côtés anode des cellules individuelles étant disposés dans des poches formées par une couche électrolytique pliée en forme de méandres et fermées au niveau de leur face supérieure et inférieure. Les cellules individuelles sont constituées, de manière connue, d'électrodes pourvues de conducteurs d'amenée et d'évacuation de courant, ainsi éventuellement que d'une couche de diffusion et de répartiteurs de flux des deux côtés de la couche électrolytique. Les conducteurs individuels d'amenée et d'évacuation de courant sont connectés électriquement de manière telle qu'il en résulte une connexion en série ou en parallèle. En outre, l'amenée ou l'évacuation du fluide d'anode ou du fluide de cathode pour toutes les poches ouvertes respectivement du côté de l'anode ou du côté de la cathode de l'espace d'anode ou de cathode peut avoir lieu en commun sans qu'une répartition et une étanchéification individuelles, habituelles dans un empilement de plaques en parallèle, de cellules successives soit nécessaire. Au lieu de cela, l'étanchéification entre l'espace d'anode et l'espace de cathode est garantie par la couche électrolytique pliée et par les deux éléments d'étanchéité supérieur et inférieur.
EP04804231A 2003-12-23 2004-12-22 Ensemble cellules electrochimiques a structure en forme de poches Withdrawn EP1706914A2 (fr)

Applications Claiming Priority (2)

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PCT/EP2004/014637 WO2005064731A2 (fr) 2003-12-23 2004-12-22 Ensemble cellules electrochimiques a structure en forme de poches

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GB2517425A (en) * 2013-08-19 2015-02-25 Intelligent Energy Ltd A fuel cell and its method of manufacture
DE102016117984B4 (de) 2016-09-23 2021-02-18 Kuntze Instruments Gmbh Vergussverfahren zum Anbringen von mindestens zwei Elektroden an einer elektrochemischen Messzelle mit einem ablösbaren Montagehilfsträger
DE102016122285A1 (de) * 2016-11-19 2018-05-24 Friedrich-Schiller-Universität Jena Redox-Flow-Batterie zur Speicherung elektrischer Energie mit radial angeordneten Hohlfasermembranen
AT16961U1 (fr) * 2019-04-04 2021-01-15 Zieger Johannes
DE102019212754A1 (de) * 2019-08-26 2021-03-04 Robert Bosch Gmbh Brennstoffzelle
GB201915438D0 (en) * 2019-10-24 2019-12-11 Ceres Ip Co Ltd Metal-supported cell unit

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WO2005064731A2 (fr) 2005-07-14

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