WO2009073453A2 - Supports d'électrode dans des plénums de distribution de fluide dans des piles à combustible - Google Patents

Supports d'électrode dans des plénums de distribution de fluide dans des piles à combustible Download PDF

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Publication number
WO2009073453A2
WO2009073453A2 PCT/US2008/084580 US2008084580W WO2009073453A2 WO 2009073453 A2 WO2009073453 A2 WO 2009073453A2 US 2008084580 W US2008084580 W US 2008084580W WO 2009073453 A2 WO2009073453 A2 WO 2009073453A2
Authority
WO
WIPO (PCT)
Prior art keywords
fuel cell
flow field
plenum
field plate
porous support
Prior art date
Application number
PCT/US2008/084580
Other languages
English (en)
Other versions
WO2009073453A3 (fr
Inventor
Julie Bellerive
Original Assignee
Bdf Ip Holdings Ltd.
Ballard Material Products Inc.
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 Bdf Ip Holdings Ltd., Ballard Material Products Inc. filed Critical Bdf Ip Holdings Ltd.
Publication of WO2009073453A2 publication Critical patent/WO2009073453A2/fr
Publication of WO2009073453A3 publication Critical patent/WO2009073453A3/fr

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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
    • H01M8/02—Details
    • H01M8/0271—Sealing or supporting means around electrodes, matrices or membranes
    • 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 present invention relates to structures and methods for mechanically supporting fuel cell electrodes in the vicinity of the fluid distribution plenums in some flow field plates.
  • it relates to plenum inserts for flow field plates in solid polymer electrolyte fuel cells.
  • Fuel cells are devices in which fuel and oxidant fluids electrochemically react to generate electricity.
  • a type of fuel cell being developed for various commercial applications is the solid polymer electrolyte fuel cell which employs a membrane electrode assembly (MEA) comprising a solid polymer electrolyte or ion exchange membrane disposed between two electrodes.
  • MEA membrane electrode assembly
  • Each electrode comprises an appropriate catalyst, preferably located next to the solid polymer electrolyte.
  • the catalyst may, for example, be a metal black, an alloy, or a supported metal catalyst such as platinum on carbon.
  • the catalyst may be disposed in a catalyst layer, and the catalyst layer typically contains ionomer, which may be similar to that used for the solid polymer electrolyte (for example, Nafion ® ).
  • the electrode may also contain a fluid diffusion layer (typically a porous, electrically conductive sheet material) that may be employed for purposes of mechanical support and/or reactant distribution.
  • a fluid diffusion layer typically a porous, electrically conductive sheet material
  • these fluid diffusion layers are referred to as gas diffusion layers (GDL)
  • the electrodes are referred to as gas diffusion electrodes (GDE).
  • Flow field plates are typically also employed adjacent the electrodes in solid polymer electrolyte fuel cells. Fluid distribution features including inlet and outlet ports, fluid distribution plenums, and numerous fluid channels are formed in the surface of the plates adjacent the electrodes in order to distribute reactant fluids to, and remove reaction by-products from, the electrodes.
  • the flow field plates also typically serve as separator plates to separate one fuel cell from another in a series stack of fuel cells. (For commercial applications, a plurality of fuel cells are generally stacked in series in order to deliver a greater output voltage.)
  • the flow field plates also provide a path for electrical and thermal conduction. And, it is the flow field plates that also generally provide mechanical support and dimensional stability to the MEAs in the cells.
  • the components making up the typical MEA are quite thin and have relatively low structural stiffness.
  • the electrolyte is an ionomer plastic material on the order of 25 microns thick.
  • the fluid diffusion layers are typically porous carbonaceous webs (such as a paper or fabric) with thickness ranging between about 100 to 200 microns.
  • the MEA can deflect into any larger open areas in the adjacent flow field plates. This can result in damage to the MEA and the deflected MEA can also block any fluid flow that was intended to occur in those open areas of the flow field plates.
  • the largest open areas may be in the vicinity of the reactant fluid inlet and outlet ports where plenums are often incorporated for purposes of distributing the fluids to and from the more complex structured flow field channels.
  • a fuel cell of the invention comprises an electrolyte and cathode and anode electrodes adjacent the electrolyte. At least one of the electrodes has a flow field plate adjacent it, in which the flow field plate comprises fluid channels in the surface adjacent the electrode, a fluid inlet and a fluid outlet port, a plenum fluidly connecting one of the ports to the fluid channels, and a porous support inserted in the plenum.
  • Porous support embodiments of the invention provide mechanical support for the electrode and prevent it from deflecting into the plenum, without itself significantly restricting flow and hence fuel cell performance. Generally then, the porous support is selected such that the pressure drop across the plenum comprising the inserted porous support is less than 10%, and preferably less than 5%, of the pressure drop across the entire flow field plate.
  • a suitable support can be made of a plastic, such as polypropylene. Further, the support can be a mesh made of overlapping fibres. In this case, mechanical support primarily is provided where the fibers intersect.
  • Openings in the porous support are of a small enough size that unsupported spans of the adjacent electrode surface are not too large.
  • openings less than or about 1 mm in size can be suitable.
  • the support can be less than about 1 mm thick.
  • the invention is particularly suitable for fuel cell designs employing flow field plates having a plurality of parallel linear fluid channels, an inlet plenum, and an outlet plenum, in which the inlet and outlet ports are at opposite ends of the linear fluid channels, and the inlet and outlet plenums connect the inlet and outlet ports to the linear fluid channels.
  • Porous supports are preferably used in each of these plenums.
  • the invention is also particularly suitable for fuel cell designs employing backfeed holes in the inlet and outlet ports.
  • Figure 1 is a schematic cross-sectional view of a single solid polymer electrolyte (SPE) fuel cell.
  • SPE single solid polymer electrolyte
  • Figure 2 is a schematic view of one embodiment of the invention in which a flow field plate for a SPE fuel cell has a plastic mesh support in a gas distribution plenum.
  • Figure 3 is a polarization plot comparing voltage versus current density for the inventive and comparative fuel cells in the Examples.
  • FIG. 1 A general schematic cross-sectional view of a single solid polymer electrolyte (SPE) fuel cell 1 is shown in Figure 1.
  • Fuel cell 1 comprises ionomer electrolyte 2, anode gas diffusion electrode (GDE) 3, cathode GDE 4, anode flow field plate 9, and cathode flow field plate 10.
  • Anode GDE 2 comprises gas diffusion layer (GDL) 5 and catalyst layer 7.
  • Cathode GDE 3 comprises GDL 6 and catalyst layer 8.
  • Anode and cathode catalyst layers 7, 8 are adjacent electrolyte 2.
  • Anode and cathode GDLs 5, 6 are adjacent flow field plates 9 and 10, respectively.
  • Anode and cathode flow field plates 9, 10 have fluid distribution channels 16, 18 formed in the surface adjacent the GDLs for purposes of distributing reactants to and removing reaction products from the GDEs.
  • the walls 17, 19 of fluid distribution channels 16, 19 provide mechanical support to GDLs 5, 6 and also provide electrical and thermal contact thereto.
  • Typical suitable base materials for GDLs 5, 6 include carbonized or graphitized carbon fiber non-woven mats such as TGP-H-050 (Toray Industries Inc., Tokyo, Japan), and AvCarb ® P50 and EP-40 (Ballard Material Products Inc., Lowell, MA). These porous carbon substrates may then be coated or impregnated with various other materials as desired in order to alter certain characteristics such as wettability, porosity, conductivity, etc.
  • Flow field plates 9, 10 may be made of a suitable carbonaceous material, such as expanded graphite that has been impregnated with a suitable filler to reduce porosity and improve certain mechanical characteristics.
  • FIG. 2 shows a schematic view of the end of a flow field plate 20 that may be employed in an automotive SPE fuel cell stack. Developmental automotive stacks frequently use a high aspect ratio design in which the cell length is significantly greater than the width.
  • flow field plate 20 comprises manifold openings for the various fluids supplied to the fuel cell stack, namely fuel inlet manifold opening 21, cathode inlet manifold opening 22, and coolant inlet manifold opening 23.
  • Figure 2 specifically shows the surface of the inlet end of an anode flow field plate that is adjacent an anode GDL.
  • a preferred flow field design is shown that employs a plurality of parallel linear fuel distribution channels 24.
  • Fuel reactant is generally provided throughout the fuel cell stack via the fuel inlet manifold that is formed by the stack of fuel inlet manifold openings 22 in adjacent cells in the stack.
  • Fuel is delivered to fuel backfeed inlet port 26 via a passageway along the back surface of flow field plate 20 (not shown).
  • Fuel then enters gas distribution plenum 28 and is distributed to the plurality of inlets of fuel flow channels 24.
  • plastic mesh support 25 is provided in plenum 28 to provide mechanical support to an adjacent anode GDL. Support 25 provides numerous points of support over the relatively large open area occupied by plenum 28.
  • An appropriate support 25 has to provide adequate mechanical support to the adjacent anode GDL without adversely affecting fuel flow distribution to fuel flow field channels 24.
  • the porous support is selected such that the pressure drop across the plenum, with the porous support inserted, is less than 10%, and preferably less than 5%, of the pressure drop across the entire flow field plate.
  • meshes can be suitable for this purpose. For instance, meshes less than about 1 mm thick and with mesh openings less than or about 1 mm in size can be suitable. However, foams and/or other like materials may also be employed.
  • Suitable materials for the insert include plastics, metals, or ceramics. Metals may be advantageous in that they additionally provide electrical and thermal contact in the plenum region. However, the fuel cell environment is quite corrosive and this places restrictions on what metal embodiments may be employed (e.g., stainless steels with corrosion resistant coatings). Suitable plastic materials include polypropylene, PTFE, and nylon.
  • porous support of the invention at the inlet end of an anode flow field plate
  • porous supports may be used at inlet and/or outlet ends of any flow field plate (anode, cathode, or in principle coolant) as is considered desirable and there is a need for support.
  • a comparative conventional solid polymer fuel cell was constructed comprising a 25 micrometer thick Nafion ® electrolyte, platinum catalyst based gas diffusion electrodes (which employed EP-40 and P50 carbon fiber mats on the cathode and anode respectively), and expanded graphite flow field plates. Both the cathode and anode flow field plates were similar in design to that depicted in Figure 2.
  • Another inventive fuel cell was constructed in a similar manner except that porous plastic supports were inserted in the inlet and outlet plenums in the flow field plates. The plenum dimensions were 42 mm by 8 mm by 760 micrometers.
  • the plastic supports were cut from extruded polypropylene mesh that was 760 micron thick (i.e., same as depth of plenums), had strands that were 380 microns in diameter, and in which there were 7.1 strands/cm (implying strand centers were 1408 micron apart and the mesh openings were about 1028 micron in size).
  • the weave pattern of the mesh was rectangular and the mesh inserts were oriented in the plenums such that the weave direction was at 45 degrees to that of the parallel linear flow fields in the flow field plates.
  • FIG. 3 shows the polarization plots of the comparative fuel cell (determined twice) and the inventive fuel cell comprising the porous supports in the flow field plate plenums.
  • the polarization plots of the two fuel cells are essentially the same over the operating current density range. Only at the highest current density is there any possible indication of an effect on performance. Even if so, in practice this is not significant.
  • the GDLs in the comparative cell actually cracked.
  • the inventive fuel cell was also subjected to a 22 psi cross pressure test. Unlike the comparative cell, the GDL here showed no such damage (i.e., no "puffing up” or deflection) and no increase in pressure drop was observed.

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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

Pour réduire une dimension et améliorer une performance dans des piles à combustible, des électrodes plus fines et plus poreuses sont employées de façon souhaitable. Cependant, de telles électrodes sont davantage sujettes à une déflexion lorsqu'elles sont soumises aux pressions de fluide que l'on trouve dans la pile à combustible. Une déflexion est davantage susceptible de se produire sur des zones non supportées plus importantes, telles que les plénums de distribution de gaz dans certaines conceptions de pile à combustible, et le résultat peut être le blocage des plénums. Certains supports poreux peuvent être introduits à l'intérieur des plénums, de telle sorte que les électrodes sont supportées à l'encontre d'une déflexion sans affecter de façon défavorable la performance de pile à combustible.
PCT/US2008/084580 2007-11-30 2008-11-24 Supports d'électrode dans des plénums de distribution de fluide dans des piles à combustible WO2009073453A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US99162207P 2007-11-30 2007-11-30
US60/991,622 2007-11-30

Publications (2)

Publication Number Publication Date
WO2009073453A2 true WO2009073453A2 (fr) 2009-06-11
WO2009073453A3 WO2009073453A3 (fr) 2010-03-18

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103354292A (zh) * 2009-12-07 2013-10-16 财团法人工业技术研究院 燃料电池系统
DE102021205800A1 (de) 2021-02-08 2022-08-11 Cellcentric Gmbh & Co. Kg Separatorplatte für einen Brennstoffzellenstapel

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6015633A (en) * 1998-10-07 2000-01-18 Plug Power, L.L.C. Fluid flow plate for water management, method for fabricating same, and fuel cell employing same
EP1020942A1 (fr) * 1997-05-14 2000-07-19 SANYO ELECTRIC Co., Ltd. Cellule electrochimique a polymere solide permettant de fournir de maniere constante d'excellentes caracteristiques de production d'energie
US20040115500A1 (en) * 2001-06-15 2004-06-17 Yasuji Ogami Polymer electrolyte fuel cell and power-generating system with polymer electrolyte fuel cells
EP1777770A1 (fr) * 2005-10-20 2007-04-25 Samsung SDI Co., Ltd. Système de pile à combustible semi-passive
WO2008030504A1 (fr) * 2006-09-07 2008-03-13 Bdf Ip Holdings Ltd. Dispositif et procédé pour la gestion de fluides dans un empilement de piles à combustible

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1020942A1 (fr) * 1997-05-14 2000-07-19 SANYO ELECTRIC Co., Ltd. Cellule electrochimique a polymere solide permettant de fournir de maniere constante d'excellentes caracteristiques de production d'energie
US6015633A (en) * 1998-10-07 2000-01-18 Plug Power, L.L.C. Fluid flow plate for water management, method for fabricating same, and fuel cell employing same
US20040115500A1 (en) * 2001-06-15 2004-06-17 Yasuji Ogami Polymer electrolyte fuel cell and power-generating system with polymer electrolyte fuel cells
EP1777770A1 (fr) * 2005-10-20 2007-04-25 Samsung SDI Co., Ltd. Système de pile à combustible semi-passive
WO2008030504A1 (fr) * 2006-09-07 2008-03-13 Bdf Ip Holdings Ltd. Dispositif et procédé pour la gestion de fluides dans un empilement de piles à combustible

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103354292A (zh) * 2009-12-07 2013-10-16 财团法人工业技术研究院 燃料电池系统
DE102021205800A1 (de) 2021-02-08 2022-08-11 Cellcentric Gmbh & Co. Kg Separatorplatte für einen Brennstoffzellenstapel

Also Published As

Publication number Publication date
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