WO2002013286A2 - Electrochemical cell comprising electrically conductive bipolar plates or end plates made of polymer composite material - Google Patents

Electrochemical cell comprising electrically conductive bipolar plates or end plates made of polymer composite material Download PDF

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Publication number
WO2002013286A2
WO2002013286A2 PCT/DE2001/002922 DE0102922W WO0213286A2 WO 2002013286 A2 WO2002013286 A2 WO 2002013286A2 DE 0102922 W DE0102922 W DE 0102922W WO 0213286 A2 WO0213286 A2 WO 0213286A2
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Prior art keywords
electrochemical cell
metal fibers
conductivity
plastic
carbon
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PCT/DE2001/002922
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German (de)
French (fr)
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WO2002013286A3 (en
Inventor
Stefan Höller
Uwe Küter
Original Assignee
Hoeller Stefan
Kueter Uwe
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Application filed by Hoeller Stefan, Kueter Uwe filed Critical Hoeller Stefan
Priority to AU2001289550A priority Critical patent/AU2001289550A1/en
Publication of WO2002013286A2 publication Critical patent/WO2002013286A2/en
Publication of WO2002013286A3 publication Critical patent/WO2002013286A3/en

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    • 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
    • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
    • H01M8/0204—Non-porous and characterised by the material
    • H01M8/0223—Composites
    • H01M8/0226—Composites in the form of mixtures
    • 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
    • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
    • H01M8/0204—Non-porous and characterised by the material
    • H01M8/0206—Metals or alloys
    • 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
    • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
    • H01M8/0204—Non-porous and characterised by the material
    • H01M8/0213—Gas-impermeable carbon-containing materials
    • 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
    • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
    • H01M8/0204—Non-porous and characterised by the material
    • H01M8/0221—Organic resins; Organic polymers
    • 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, in particular a fuel cell, according to the features specified in the preamble of claim 1.
  • Electrochemical cells are, for example, electrolysis cells or fuel cells.
  • a known type of such cells works with a gas-tight and ion-permeable polymer electrolyte membrane, on the one hand an anode and on the other hand a cathode.
  • Such anodes or cathodes are usually designed as gas diffusion electrodes, as are described, for example, in DE 195 44 323 A1. Through a gas diffusion electrode, gas reaches the surface of the membrane, the electrode being catalytically coated, as a result of which the desired catalytic oxidation of the fuel takes place.
  • the gas diffusion electrodes are usually electrically conductive
  • Supported plate via which the contact is made.
  • This is either an end plate or, if several fuel cells are connected in series to form a stack, a bipolar plate which supports gas diffusion electrodes on both sides.
  • the gas supply to the gas diffusion electrodes usually takes place via these plates, for which purpose corresponding
  • Channels are provided in the plates. Such a structure can also be found in electrolysis cells, in particular in fuel cells which can be operated reversibly.
  • bipolar plates or end plates therefore have to fulfill several tasks. They must be gas-tight, they must be good conductors and should Beyond that, it can be inexpensive to manufacture, since such fuel cells are usually connected in series to form a stack in which a large number of such plates is required. Because of the channels provided on the plate surface or surface, injection molding is currently the only possible production method, since machining such a plate would be disproportionately expensive. However, due to the conductivity requirements, these plates are still complex to manufacture. A high proportion of carbon is added to the plastic to maintain good conductivity. The addition of metal powder, which is otherwise known for increasing the conductivity, is not suitable for this application, since then the
  • the object of the invention is to design a generic electrochemical cell, in particular a fuel cell, in such a way that it can be inexpensively manufactured in large quantities, in particular the electrically conductive bipolar plates or the electrically conductive end plates.
  • the end plates or, in the case of a stack of cells, the bipolar plates and the end plates from plastic as injection-molded parts in a single fuel cell or an electrolysis cell, and to increase the conductivity on the one hand the plastic is a non-metallic conductive substance and on the other hand metal fibers admix.
  • the contact resistance in the area of the surface of the plate is not decisively determined by the metal fibers, but by the non-metallic material, in particular carbon, which increases the conductivity and is insensitive to this extent.
  • the metal fibers thus ensure good conductivity within the material, whereas the non-metallic material ensures a low contact resistance and the conduction between the metal fibers.
  • filler material non-metallic conductive material and metal fibers
  • the metal fibers do not need to be made of a noble metal, but should preferably consist of stainless steel, titanium or an alloy thereof, in order to be largely insensitive to oxidation even in the surface area. In addition, this property is also advantageous when using a noble metal, but should preferably consist of stainless steel, titanium or an alloy thereof, in order to be largely insensitive to oxidation even in the surface area. In addition, this property is also advantageous when using a noble metal, but should preferably consist of stainless steel, titanium or an alloy thereof, in order to be largely insensitive to oxidation even in the surface area. In addition, this property is also advantageous when using a
  • the proportion of metal fibers is preferred between 1 and 15 percent by weight, preferably in the range of about 7 to 8% based on the total weight of the injection molded component. With a suitable choice of diameter and length, the metal fibers still have the positive property that they improve the strength properties of the base material, in particular with regard to tensile and bending strength. Since the
  • Metal fibers are relatively heavy compared to plastic, the weight percentages given above generally correspond to volume percentages of less than 3%. This low metal fiber content means that the plastics provided with it, in particular thermoplastics, are easy to process and generally do not require any special precautions when processing the
  • thermoplastic materials for example polyamide
  • thermoplastic materials are enriched with up to 40% carbon in order to achieve a conductivity of the plastic.
  • the conductivity that can be achieved in this way still represents a compromise between economical production and the technical requirements with regard to conductivity. If more carbon were added to the plastic to increase the conductivity, this would no longer be sprayable, which would significantly increase the production costs. According to the invention it is therefore provided that the basic conductivity of the plastic
  • metal fibers are additionally admixed with the plastic. Part of the carbon admixture is replaced by the metal fibers, which can significantly increase the conductivity. However, the material is conditioned in such a way that the sprayability is fully retained.
  • Metal fibers are preferably used which have an average diameter of 8 ⁇ m and a length of about 5 mm. These metal fibers are preferably plastic-coated the actual injection molding material, for. B. a polyamide added. The intensive mixing takes place within the extruder, whereby the plastic coating of the metal fibers melts and is distributed in the remaining plastic.
  • the non-metallic substance is also preferably added in fiber form, for example in the form of carbon fibers with an average diameter of 12 ⁇ m and a length of about 6 mm.
  • the carbon fibers are also mixed into the granules before the extrusion process together with the metal fibers, with intensive mixing taking place within the extruder, which however leads to the carbon fibers breaking and then having an average length of about 100 ⁇ m.
  • the total proportion of carbon fibers and metal fibers should not exceed 40% by weight in order to ensure the sprayability of the material.
  • Fig. 1 shows the schematic structure of a fuel cell
  • Fig. 2 shows a section through an end plate of such a fuel cell.
  • the structure of the fuel cell essentially corresponds to that from DE 195 44
  • 323 AI known. 1 consists of an end plate 1, a gas diffusion electrode 2, a gas-tight and ion-permeable polymer electrolyte membrane 3, a further gas diffusion electrode 4 and a second end plate 5, which are fixed by sealing frame parts and mechanical fastenings (not shown) and are tightly connected.
  • the end plates 1 and 5 meandering channels are provided, which are open to the gas diffusion membrane.
  • the reaction gases for example hydrogen through the end plate 5 and oxygen through the end plate 1, are supplied via the end plates 1 and 5, which are in conductive contact with the gas diffusion electrodes 2 and 4, respectively.
  • the gas passes into the channels open to the gas diffusion electrode and reacts with the catalysts applied there in the form of catalytic combustion.
  • the resulting electrical energy can be removed via the end plates 1 and 5.
  • Fig. 2 the structure of these end plates described above is shown schematically.
  • 6 shows a thermoplastic base material, here a polyamide, to which carbon fibers 7 and metal fibers 8 have been added before the extrusion process.
  • the comparatively long metal fibers are arranged spatially distributed in the plastic and form a three-dimensional structure with a net-like structure.
  • the metal fibers which are several millimeters long, bridge the large distances in the material, which ensures good conductivity.
  • the carbon fibers 7 present in a substantially greater number form conductive bridges.
  • the carbon fibers 7 serve to achieve the lowest possible contact resistance when contacting from the surface.
  • the end plates 1 and 5 are injection molded, with the base material in the form of granules, a polyamide, 30% by weight carbon fibers and 10% by weight plastic-coated stainless steel metal fibers, which have been mixed intensively with one another within the extruder screw, the plastic coating of the metal fibers 8 melted and thus a structure similar to that shown in Fig. 2 has arisen.

Abstract

The invention relates to a fuel cell comprising a polymer electrolyte membrane and two gas diffusion electrodes, which are arranged on both sides of said membrane and which are terminated by electrically conductive end plates. The end plates are produced in an injection molding and are comprised of a thermoplastic base material (6) and of a non-metallic substance (7) that increases the conductivity, for example carbon. Metal fibers (8) are incorporated inside the base material in order to additionally increase the conductivity.

Description

Elektrochemische Zelle Electrochemical cell
Die Erfindung betrifft eine elektrochemische Zelle, insbesondere eine Brenn- stoffzelle, gemäß den im Oberbegriff des Anspruchs 1 angegebenen Merkmalen.The invention relates to an electrochemical cell, in particular a fuel cell, according to the features specified in the preamble of claim 1.
Elektrochemische Zellen sind beispielsweise Elektrolysezellen oder Brennstoffzellen. Eine bekannte Bauart solcher Zellen arbeitet mit einer gasdichten und ionendurchlässigen Polymerelektrolytmembran, an der einerseits eine Anode und andererseits eine Kathode anliegt. Solche Anoden oder Kathoden sind üblicherweise als Gasdiffusionselektroden ausgebildet, so wie sie beispielhaft in DE 195 44 323 AI beschrieben sind. Durch eine Gasdiffusionselektrode gelangt Gas flächig zu der Membran, wobei die Elektrode katalytisch beschichtet ist, wodurch die gewünschte katalytische Oxidation des Brennstoffs erfolgt. Die Gasdiffusionselektroden sind üblicherweise durch eine elektrisch leitfähigeElectrochemical cells are, for example, electrolysis cells or fuel cells. A known type of such cells works with a gas-tight and ion-permeable polymer electrolyte membrane, on the one hand an anode and on the other hand a cathode. Such anodes or cathodes are usually designed as gas diffusion electrodes, as are described, for example, in DE 195 44 323 A1. Through a gas diffusion electrode, gas reaches the surface of the membrane, the electrode being catalytically coated, as a result of which the desired catalytic oxidation of the fuel takes place. The gas diffusion electrodes are usually electrically conductive
Platte abgestützt, über welche die Kontaktierung erfolgt. Hierbei handelt es sich entweder um eine Endplatte oder, wenn mehrere Brennstoffzellen zu einem Stack hintereinandergeschaltet sind, um eine bipolare Platte, welche zu beiden Seiten Gasdiffusionselektroden abstützt. Über diese Platten erfolgt üblicher- weise auch die Gaszufuhr zu den Gasdiffusionselektroden, wozu entsprechendeSupported plate, via which the contact is made. This is either an end plate or, if several fuel cells are connected in series to form a stack, a bipolar plate which supports gas diffusion electrodes on both sides. The gas supply to the gas diffusion electrodes usually takes place via these plates, for which purpose corresponding
Kanäle in den Platten vorgesehen sind. Ein solcher Aufbau ist auch bei Elektrolysezellen zu finden, insbesondere bei reversibel betreibbaren Brennstoffzellen.Channels are provided in the plates. Such a structure can also be found in electrolysis cells, in particular in fuel cells which can be operated reversibly.
Diese bipolaren Platten bzw. Endplatten haben also mehrere Aufgaben zu erfüllen. Sie müssen gasdicht sein, sie müssen gut leitend sein und sollen darü- ber hinaus kostengünstig in der Herstellung sein, da solche Brennstoffzellen üblicherweise zu einem Stack in Reihe geschaltet werden, in dem eine Vielzahl solcher Platten benötigt wird. Wegen der auf der Plattenoberfläche bzw. -ober- flachen vorgesehenen Kanäle kommt als Herstellungsverfahren derzeit nur das Spritzgießen in Frage, da eine spanabhebende Bearbeitung einer solchen Platte unverhältnismäßig teuer wäre. Wegen der Leitfähigkeitsanforderungen sind diese Platten jedoch nach wie vor aufwändig in der Herstellung. Dem Kunststoff wird zum Erhalt einer guten Leitfähigkeit ein hoher Kohlenstoffanteil beigemengt. Das sonst zur Leitfähigkeitssteigerung bekannte Beimengen von Metallpulver ist für diesen Anwendungszweck nicht geeignet, da dann dieThese bipolar plates or end plates therefore have to fulfill several tasks. They must be gas-tight, they must be good conductors and should Beyond that, it can be inexpensive to manufacture, since such fuel cells are usually connected in series to form a stack in which a large number of such plates is required. Because of the channels provided on the plate surface or surface, injection molding is currently the only possible production method, since machining such a plate would be disproportionately expensive. However, due to the conductivity requirements, these plates are still complex to manufacture. A high proportion of carbon is added to the plastic to maintain good conductivity. The addition of metal powder, which is otherwise known for increasing the conductivity, is not suitable for this application, since then the
Oberflächen der Platten aufgrund der mit ihnen in Kontakt kommenden Medien oxidieren können, wodurch der Übergangswiderstand unzulässig steigt. Das Beimengen von Edelmetallen in entsprechender Konzentration kommt aus Kostengründen nicht in Betracht.Surfaces of the plates can oxidize due to the media coming into contact with them, which increases the contact resistance inadmissibly. The admixture of precious metals in a corresponding concentration is out of the question for cost reasons.
Vor diesem Hintergrund liegt der Erfindung die Aufgabe zugrunde, eine gattungsgemäße elektrochemische Zelle, insbesondere eine Brennstoffzelle, so auszubilden, dass sie in großen Stückzahlen kostengünstig herstellbar ist, insbesondere die elektrisch leitfähigen bipolaren Platten bzw. die elektrisch leitfähigen Endplatten.Against this background, the object of the invention is to design a generic electrochemical cell, in particular a fuel cell, in such a way that it can be inexpensively manufactured in large quantities, in particular the electrically conductive bipolar plates or the electrically conductive end plates.
Diese Aufgabe wird gemäß der Erfindung durch die in Anspruch 1 angegebenen Merkmale gelöst. Vorteilhafte Ausgestaltungen der Erfindung sind in den Unteransprüchen sowie der nachfolgenden Beschreibung angegeben.This object is achieved according to the invention by the features specified in claim 1. Advantageous embodiments of the invention are specified in the subclaims and in the description below.
Gemäß der Erfindung ist somit vorgesehen, bei einer einzelnen Brennstoffzelle oder einer Elektrolysezelle die Endplatten bzw. bei einem Stack von Zellen die bipolaren Platten und die Endplatten aus Kunststoff als Spritzgussteile herzustellen und dabei zur Erhöhung der Leitfähigkeit einerseits dem Kunststoff einen nichtmetallischen leitfähigen Stoff und andererseits Metallfasern zuzumischen.According to the invention, it is thus provided to manufacture the end plates or, in the case of a stack of cells, the bipolar plates and the end plates from plastic as injection-molded parts in a single fuel cell or an electrolysis cell, and to increase the conductivity on the one hand the plastic is a non-metallic conductive substance and on the other hand metal fibers admix.
Diese die Leitfähigkeit erhöhenden Komponenten haben den Effekt, dass durch den nichtmetallischen Stoff, beispielsweise auf Kohlenstoff basis, eine Grundleitfähigkeit des Werkstoffes geschaffen wird, die jedoch nicht so hoch wie bei Platten bekannter Art aus Spritzguss sein muss, wodurch die Herstellung deutlich vereinfacht und verbilligt wird. Diese Grundleitfähigkeit dient im Wesentli- chen dazu, den Übergangswiderstand an der Oberfläche gering zu halten und die kurzen Brücken innerhalb des Werkstoffes zwischen den Metallfasern zu bilden. Die eigentliche Leitfähigkeit hingegen wird durch die im Kunststoff eingegliederten Metallfasern gewährleistet. Da die Metallfasern innerhalb des Werkstoffes durch den Werkstoff selbst geschützt sind, besteht die Gefahr einer Oxidation nur im Bereich der Oberfläche. Der Übergangswiderstand im Bereich der Oberfläche der Platte wird jedoch nicht entscheidend durch die Metallfasern, sondern durch den die Leitfähigkeit erhöhenden nichtmetallischen Werkstoff, insbesondere Kohlenstoff, bestimmt, der insoweit unempfindlich ist. Durch die Metallfasern wird also eine gute Leitfähigkeit innerhalb des Werkstoffes sicher- gestellt, wohingegen der nichtmetallische Werkstoff für einen kleinen Übergangswiderstand und die Leitung zwischen den Metallfasern sorgt. Es kann somit bei vergleichsweise geringem Anteil von Zusatzwerkstoff (nicht metallischer leitender Stoff sowie Metallfasern) eine hohe Leitfähigkeit im Kunststoff erzielt werden, ohne die sonst bei hoher Leitfähigkeit auftretenden Festigkeits- probleme im Werkstoff oder Herstellungsprobleme zu induzieren.These components which increase the conductivity have the effect that the non-metallic substance, for example based on carbon, a basic conductivity of the material is created, which, however, does not have to be as high as in the case of plates of known type made from injection molding, as a result of which the production is significantly simplified and cheaper. This basic conductivity essentially serves to keep the contact resistance on the surface low and to form the short bridges within the material between the metal fibers. The actual conductivity, on the other hand, is guaranteed by the metal fibers integrated into the plastic. Since the metal fibers within the material are protected by the material itself, there is a risk of oxidation only in the area of the surface. However, the contact resistance in the area of the surface of the plate is not decisively determined by the metal fibers, but by the non-metallic material, in particular carbon, which increases the conductivity and is insensitive to this extent. The metal fibers thus ensure good conductivity within the material, whereas the non-metallic material ensures a low contact resistance and the conduction between the metal fibers. Thus, with a comparatively small proportion of filler material (non-metallic conductive material and metal fibers), a high conductivity can be achieved in the plastic without inducing the strength problems in the material or manufacturing problems that otherwise occur with high conductivity.
Die Metallfasern brauchen nicht aus einem Edelmetall zu sein, sollten jedoch bevorzugt aus Edelstahl, Titan oder einer Legierung daraus bestehen, um auch im Oberflächenbereich weitgehend unempfindlich gegen Oxidation zu sein. Darüber hinaus ist diese Eigenschaft auch von Vorteil bei Verwendung einerThe metal fibers do not need to be made of a noble metal, but should preferably consist of stainless steel, titanium or an alloy thereof, in order to be largely insensitive to oxidation even in the surface area. In addition, this property is also advantageous when using a
Vielzahl von Kunststoffen, die nicht vollständig diffusionsdicht sind, so dass bei Langzeiteinwirkungen auch eine Oxidation innerhalb des Werkstoffes eintreten könnte.A large number of plastics that are not completely diffusion-tight, so that long-term exposure could lead to oxidation within the material.
Schon ein vergleichsweise geringer Metallfaseranteil bewirkt eine gute Leitfähigkeit des Kunststoffs. Der Anteil der Metallfasern wird vorzugsweise zwischen 1 und 15 Gewichtsprozenten, vorzugsweise im Bereich von etwa 7 bis 8 % bezogen auf das Gesamtgewicht des Spritzgussbauteils, liegen. Dabei haben bei geeigneter Wahl von Durchmesser und Länge die Metallfasem noch die positive Eigenschaft, dass sie die Festigkeitseigenschaften des Grundwerkstoffes verbessern, insbesondere im Hinblick auf Zug- und Biegefestigkeit. Da dieEven a comparatively low proportion of metal fiber results in good conductivity of the plastic. The proportion of metal fibers is preferred between 1 and 15 percent by weight, preferably in the range of about 7 to 8% based on the total weight of the injection molded component. With a suitable choice of diameter and length, the metal fibers still have the positive property that they improve the strength properties of the base material, in particular with regard to tensile and bending strength. Since the
Metallfasem gegenüber dem Kunststoff verhältnismäßig schwer sind, entsprechen die vorstehend angegebenen Gewichtsprozente in der Regel Volumenprozenten von unter 3 %. Dieser geringe Metallfaseranteil fuhrt dazu, dass die damit versehenen Kunststoffe, insbesondere Thermoplaste, gut zu verarbeiten sind und in der Regel keine besonderen Vorkehrungen bei der Verarbeitung desMetal fibers are relatively heavy compared to plastic, the weight percentages given above generally correspond to volume percentages of less than 3%. This low metal fiber content means that the plastics provided with it, in particular thermoplastics, are easy to process and generally do not require any special precautions when processing the
Werkstoffes zu treffen sind.Material to be taken.
Nach dem Stand der Technik werden thermoplastische Kunststoffe, beispielsweise Polyamid, mit bis zu 40 % Kohlenstoff angereichert, um eine Leitfähigkeit des Kunststoffs zu erreichen. Die damit erzielbare Leitfähigkeit stellt aber immer noch einen Kompromiss zwischen wirtschaftlicher Herstellung und den technischen Anforderungen im Hinblick auf die Leitfähigkeit dar. Würde man dem Kunststoff mehr Kohlenstoff zur Erhöhung der Leitfähigkeit hinzufügen, so wäre dieser nicht mehr spritzfähig, was die Fertigungskosten erheblich erhöhen würde. Gemäß der Erfindung ist daher vorgesehen, die Grundleitfähigkeit desAccording to the prior art, thermoplastic materials, for example polyamide, are enriched with up to 40% carbon in order to achieve a conductivity of the plastic. However, the conductivity that can be achieved in this way still represents a compromise between economical production and the technical requirements with regard to conductivity. If more carbon were added to the plastic to increase the conductivity, this would no longer be sprayable, which would significantly increase the production costs. According to the invention it is therefore provided that the basic conductivity of the
Kunststoffes durch Beimengen eines die Leitfähigkeit erhöhenden nichtmetallischen Stoffes, typischerweise auf Kohlenstoffbasis, zu bewirken, beispielsweise durch Beimengen von Ruß oder Grafit, wie dies auch nach dem Stand der Technik erfolgt. Eine ganz erhebliche Leitfähigkeitssteigerung wird jedoch gemäß der Erfindung durch die zusätzlich dem Kunststoff beigemengten Metallfasem erreicht. Es wird ein Teil der Kohlenstofϊbeimengung durch die Metallfasem ersetzt, wodurch die Leitfähigkeit ganz erheblich gesteigert werden kann. Dabei wird der Werkstoff jedoch so konditioniert, dass die Spritzfähigkeit voll erhalten bleibt. Es werden bevorzugt Metallfasem eingesetzt, die einen mittleren Durchmesser von 8 μm bei einer Länge von etwa 5 mm haben. Diese Metallfasem werden bevorzugt kunststoffummantelt dem eigentlichen Spritzgusswerkstoff, z. B. einem Polyamid, zugegeben. Die intensive Durchmischung erfolgt innerhalb des Extruders, wobei die Kunststofftimmantelung der Metallfasem aufschmilzt und sich in dem übrigen Kunststoff verteilt.To effect plastic by admixing a non-metallic substance, typically based on carbon, which increases the conductivity, for example by admixing carbon black or graphite, as is also done according to the prior art. According to the invention, however, a very considerable increase in conductivity is achieved by the metal fibers additionally admixed with the plastic. Part of the carbon admixture is replaced by the metal fibers, which can significantly increase the conductivity. However, the material is conditioned in such a way that the sprayability is fully retained. Metal fibers are preferably used which have an average diameter of 8 μm and a length of about 5 mm. These metal fibers are preferably plastic-coated the actual injection molding material, for. B. a polyamide added. The intensive mixing takes place within the extruder, whereby the plastic coating of the metal fibers melts and is distributed in the remaining plastic.
Bevorzugt wird auch der nichtmetallische Stoff in Faserform zugefügt, beispielsweise in Form von Kohlefasem mit einem mittleren Durchmesser von 12 μm bei einer Länge von etwa 6 mm. Auch die Kohlefasern werden dem Granulat vor dem Extrusionsvorgang zusammen mit den Metallfasem zugemischt, wobei auch hier innerhalb des Extruders eine intensive Durchmischung stattfindet, die allerdings dazu fuhrt, dass die Kohlefasem brechen und dann eine durchschnittliche Länge von etwa 100 μm aufweisen. Der Gesamtanteil von Kohlefasem und Metallfasem sollte 40 Gewichtsprozent nicht überschreiten, um die Spritzfähigkeit des Materials zu gewährleisten.The non-metallic substance is also preferably added in fiber form, for example in the form of carbon fibers with an average diameter of 12 μm and a length of about 6 mm. The carbon fibers are also mixed into the granules before the extrusion process together with the metal fibers, with intensive mixing taking place within the extruder, which however leads to the carbon fibers breaking and then having an average length of about 100 μm. The total proportion of carbon fibers and metal fibers should not exceed 40% by weight in order to ensure the sprayability of the material.
Die Erfindung ist nachfolgend anhand eines in der Zeichnung dargestellten Ausfuhrungsbeispiels erläutert. Es zeigen:The invention is explained below using an exemplary embodiment shown in the drawing. Show it:
Fig. 1 den schematischen Aufbau einer Brennstoffzelle undFig. 1 shows the schematic structure of a fuel cell and
Fig. 2 einen Schnitt durch eine Endplatte einer solchen Brennstoffzelle.Fig. 2 shows a section through an end plate of such a fuel cell.
Der Aufbau der Brennstoffzelle entspricht im Wesentlichen dem aus DE 195 44The structure of the fuel cell essentially corresponds to that from DE 195 44
323 AI bekannten. Die in Fig. 1 in Explosionsdarstellung schematisch dargestellte Brennstoffzelle besteht aus einer Endplatte 1, einer Gasdiffusionselektrode 2, einer gasdichten und ionendurchlässigen Polymerelektrolytmembran 3, einer weiteren Gasdiffusionselektrode 4 sowie einer zweiten Endplatte 5, die über jeweils dichtende Rahmenteile und (nicht dargestellte) mechanische Befestigungen fest und dicht miteinander verbunden sind. In den Endplatten 1 und 5 sind mäanderfδrmig geführte Kanäle vorgesehen, die zur Gasdiffusionsmembran hin offen sind. Über die Endplatten 1 und 5, die leitend an den Gasdiffusionselektroden 2 bzw. 4 anliegen, werden die Reaktionsgase, beispielsweise Wasserstoff durch die Endplatte 5 und Sauerstoff durch die Endplatte 1, zu- geführt. Das Gas gelangt über die zur Gasdiffusionselektrode offenen Kanäle in diese hinein und reagiert mit den dort aufgebrachten Katalysatoren in Form einer katalytischen Verbrennung. Die dabei entstehende elektrische Energie kann über die Endplatten 1 und 5 abgenommen werden.323 AI known. 1 consists of an end plate 1, a gas diffusion electrode 2, a gas-tight and ion-permeable polymer electrolyte membrane 3, a further gas diffusion electrode 4 and a second end plate 5, which are fixed by sealing frame parts and mechanical fastenings (not shown) and are tightly connected. In the end plates 1 and 5 meandering channels are provided, which are open to the gas diffusion membrane. The reaction gases, for example hydrogen through the end plate 5 and oxygen through the end plate 1, are supplied via the end plates 1 and 5, which are in conductive contact with the gas diffusion electrodes 2 and 4, respectively. The gas passes into the channels open to the gas diffusion electrode and reacts with the catalysts applied there in the form of catalytic combustion. The resulting electrical energy can be removed via the end plates 1 and 5.
In Fig. 2 ist der einleitend beschriebene Aufbau dieser Endplatten schematisch dargestellt. Dabei ist mit 6 ein thermoplastischer Grundwerkstoff, hier ein Polyamid, dargestellt, dem vor dem Extrusionsvorgang Kohlefasem 7 sowie Metallfasern 8 beigemengt worden sind. Wie insbesondere die vergrößert dargestellte Einzelheit der Fig. verdeutlicht, liegen die vergleichsweise langen Metallfasem räumlich verteilt in dem Kunststoff angeordnet und bilden ein dreidimensionales Gebilde mit netzartiger Struktur. Die mehrere Millimeter langen Metallfasem überbrücken dabei die großen Entfernungen im Werkstoff, wodurch eine gute Leitfähigkeit erzielt wird. Im Bereich der Oberfläche und zwischen den Metallfasem 8 bilden die in wesentlich größerer Anzahl vorhande- nen Kohlefasern 7 leitende Brücken. Insbesondere im Oberflächenbereich, wo die Metallfasem korrodieren könnten, dienen die Kohlefasem 7 dazu, einen möglichst geringen Übergangswiderstand bei Kontaktierung von der Oberfläche her zu erreichen. Die Endplatten 1 und 5 sind in Spritzguss gefertigt, wobei dem als Granulat vorliegenden Grundwerkstoff, einem Polyamid, 30 Gewichts- prozent Kohlefasem und 10 Gewichtsprozent kunststoffummantelte Edelstahlmetallfasern beigemengt worden sind, die innerhalb der Extruderschnecke intensiv miteinander vermengt worden sind, wobei die Kunststoffummantelung der Metallfasem 8 aufgeschmolzen und somit ein Gefüge ähnlich dem in Fig. 2 dargestellten entstanden ist. In Fig. 2 the structure of these end plates described above is shown schematically. 6 shows a thermoplastic base material, here a polyamide, to which carbon fibers 7 and metal fibers 8 have been added before the extrusion process. As is particularly clear from the detail shown in FIG. 1, the comparatively long metal fibers are arranged spatially distributed in the plastic and form a three-dimensional structure with a net-like structure. The metal fibers, which are several millimeters long, bridge the large distances in the material, which ensures good conductivity. In the area of the surface and between the metal fibers 8, the carbon fibers 7 present in a substantially greater number form conductive bridges. In particular in the surface area where the metal fibers could corrode, the carbon fibers 7 serve to achieve the lowest possible contact resistance when contacting from the surface. The end plates 1 and 5 are injection molded, with the base material in the form of granules, a polyamide, 30% by weight carbon fibers and 10% by weight plastic-coated stainless steel metal fibers, which have been mixed intensively with one another within the extruder screw, the plastic coating of the metal fibers 8 melted and thus a structure similar to that shown in Fig. 2 has arisen.

Claims

A N S P R U C H E EXPECTATIONS
1. Elektrochemische Zelle, insbesondere Brennstoffzelle, mit einer Polymerelektrolytmembran (3) und mit mindestens einer elektrisch leitfähigen bipolaren Platte (1, 5) oder elektrisch leitfähigen Endplatte, die im Spritzguss hergestellt ist und im Wesentlichen aus Kunststoff (6) und einem die Leitfähigkeit erhöhenden nichtmetallischen Stoff (7) besteht, dadurch gekennzeichnet, dass zur weiteren Erhöhung der Leitfähigkeit Metallfasem (8) in den Kunststoff eingegliedert sind.1. Electrochemical cell, in particular fuel cell, with a polymer electrolyte membrane (3) and with at least one electrically conductive bipolar plate (1, 5) or electrically conductive end plate, which is produced by injection molding and essentially made of plastic (6) and a conductivity increasing non-metallic substance (7), characterized in that metal fibers (8) are incorporated into the plastic to further increase the conductivity.
2. Elektrochemische Zelle nach Anspruch 1, dadurch gekennzeichnet, dass die Metallfasem (8) aus Edelstahl, Titan oder einer Legierung daraus bestehen.2. Electrochemical cell according to claim 1, characterized in that the metal fibers (8) consist of stainless steel, titanium or an alloy thereof.
3. Elektrochemische Zelle nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass die Metallfasem (8) einen Anteil von 1 % bis 15 %, vorzugsweise von etwa 7 bis 8 % am Gesamtgewicht des jeweiligen Spritzgussbauteils haben.3. Electrochemical cell according to one of the preceding claims, characterized in that the metal fibers (8) have a proportion of 1% to 15%, preferably of about 7 to 8%, of the total weight of the respective injection molded component.
4. Elektrochemische Zelle nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass die Metallfasem (8) eine mittlere Länge von 2 bis 10 mm haben.4. Electrochemical cell according to one of the preceding claims, characterized in that the metal fibers (8) have an average length of 2 to 10 mm.
5. Elektrochemische Zelle nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass die Metallfasem (8) einen mittleren Durchmesser von 6 bis 20 μm haben. 5. Electrochemical cell according to one of the preceding claims, characterized in that the metal fibers (8) have an average diameter of 6 to 20 microns.
6. Elektrochemische Zelle nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass der Kunststoff ein Thermoplast, vorzugsweise ein Polyamid (6) ist und der die Leitfähigkeit erhöhende nichtmetallische Stoff Kohlenstoff in Form von Ruß oder Grafϊt ist.6. Electrochemical cell according to one of the preceding claims, characterized in that the plastic is a thermoplastic, preferably a polyamide (6) and the non-metallic substance which increases the conductivity is carbon in the form of carbon black or graphite.
7. Elektrochemische Zelle nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass der Kohlenstoff in Form von Kohlenstofffasem (7) gebildet ist. 7. Electrochemical cell according to one of the preceding claims, characterized in that the carbon is formed in the form of carbon fibers (7).
PCT/DE2001/002922 2000-08-08 2001-08-06 Electrochemical cell comprising electrically conductive bipolar plates or end plates made of polymer composite material WO2002013286A2 (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102012010994A1 (en) 2012-06-02 2013-12-05 Volkswagen Aktiengesellschaft End plate for a fuel cell and fuel cell with such

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10219384A1 (en) * 2002-04-30 2003-11-20 Proton Motor Fuel Cell Gmbh Bipolar plate for fuel cell stacks and process for their manufacture
DE102009026097A1 (en) * 2009-07-03 2011-01-05 Akwa Gmbh Method for manufacturing electrode unit for metal-air-cell that is utilized in e.g. optics, involves opening die-casting mold, and forming opening edge that is provided with cover in unbended manner
DE102021205458A1 (en) * 2021-05-28 2022-12-01 Robert Bosch Gesellschaft mit beschränkter Haftung Electrolyser, bipolar plate and method for their manufacture

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4569786A (en) * 1983-04-12 1986-02-11 Ube Industries, Ltd. Electrically conductive thermoplastic resin composition containing metal and carbon fibers
WO2000030202A1 (en) * 1998-11-18 2000-05-25 Energy Partners, L.C. Fuel cell collector plate and method of fabrication
WO2000044005A1 (en) * 1999-01-19 2000-07-27 E.I. Du Pont De Nemours And Company Injection moldable conductive aromatic thermoplastic liquid crystalline polymeric compositions
DE10041209A1 (en) * 1999-08-27 2001-08-02 Freudenberg Carl Fa Thermoplastic composition useful in an electrically conducting member, e.g. electrical connector, comprises a fully cured thermoplastic vulcanizate and electrically conducting solid fillers in specified amount

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4569786A (en) * 1983-04-12 1986-02-11 Ube Industries, Ltd. Electrically conductive thermoplastic resin composition containing metal and carbon fibers
WO2000030202A1 (en) * 1998-11-18 2000-05-25 Energy Partners, L.C. Fuel cell collector plate and method of fabrication
WO2000044005A1 (en) * 1999-01-19 2000-07-27 E.I. Du Pont De Nemours And Company Injection moldable conductive aromatic thermoplastic liquid crystalline polymeric compositions
DE10041209A1 (en) * 1999-08-27 2001-08-02 Freudenberg Carl Fa Thermoplastic composition useful in an electrically conducting member, e.g. electrical connector, comprises a fully cured thermoplastic vulcanizate and electrically conducting solid fillers in specified amount

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102012010994A1 (en) 2012-06-02 2013-12-05 Volkswagen Aktiengesellschaft End plate for a fuel cell and fuel cell with such

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