WO2018183047A1 - Plaque de champ d'écoulement pour une pile à combustible électrochimique - Google Patents

Plaque de champ d'écoulement pour une pile à combustible électrochimique Download PDF

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Publication number
WO2018183047A1
WO2018183047A1 PCT/US2018/023420 US2018023420W WO2018183047A1 WO 2018183047 A1 WO2018183047 A1 WO 2018183047A1 US 2018023420 W US2018023420 W US 2018023420W WO 2018183047 A1 WO2018183047 A1 WO 2018183047A1
Authority
WO
WIPO (PCT)
Prior art keywords
flow field
anode
cathode
landing
field plate
Prior art date
Application number
PCT/US2018/023420
Other languages
English (en)
Inventor
Ryan Christopher MCKAY
Original Assignee
Ballard Power Systems Inc.
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 Ballard Power Systems Inc., Ballard Material Products Inc. filed Critical Ballard Power Systems Inc.
Publication of WO2018183047A1 publication Critical patent/WO2018183047A1/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
    • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
    • H01M8/0258—Collectors; Separators, e.g. bipolar separators; Interconnectors characterised by the configuration of channels, e.g. by the flow field of the reactant or coolant
    • H01M8/0265—Collectors; Separators, e.g. bipolar separators; Interconnectors characterised by the configuration of channels, e.g. by the flow field of the reactant or coolant the reactant or coolant channels having varying cross sections
    • 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
    • H01M8/0258—Collectors; Separators, e.g. bipolar separators; Interconnectors characterised by the configuration of channels, e.g. by the flow field of the reactant or coolant
    • H01M8/0263—Collectors; Separators, e.g. bipolar separators; Interconnectors characterised by the configuration of channels, e.g. by the flow field of the reactant or coolant having meandering or serpentine paths
    • 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
    • H01M8/04014—Heat exchange using gaseous fluids; Heat exchange by combustion of reactants
    • 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
    • H01M8/1004—Fuel cells with solid electrolytes characterised by membrane-electrode assemblies [MEA]
    • 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 disclosure relates to electrochemical fuel cells and, particular, to flow field plates for air-cooled fuel cells.
  • Fuel cells convert reactants, namely, fuel and oxidant, to generate electric power and reaction products.
  • Polymer electrolyte membrane fuel cells (“PEM fuel cell”) employ a membrane electrode assembly (“MEA”), which comprises a solid polymer electrolyte or ion-exchange membrane disposed between the two electrodes, namely a cathode and an anode.
  • MEA membrane electrode assembly
  • a catalyst typically induces the desired electrochemical reactions at the electrodes.
  • Separator plates, or flow field plates for directing the reactants across one surface of each electrode substrate, are disposed on each side of the MEA.
  • the output voltage of an individual fuel cell under load is generally below one volt. Therefore, in order to provide greater output voltage, multiple cells are usually stacked together and are connected in series to create a higher voltage fuel cell stack. End plate assemblies are placed at each end of the stack to hold the stack together and to compress the stack components together. Compressive force effects sealing and provides adequate electrical contact between various stack components. Fuel cell stacks can then be further connected in series and/or parallel combinations to form larger arrays for delivering higher voltages and/or currents.
  • Figures 1 -4 collectively illustrate a typical design of a conventional MEA 5, with electrodes 1 ,3 sandwiching a proton exchange membrane 2 therebetween (Figure 1 ); an electrochemical cell 10 comprising an MEA 5 between flow field plates 1 1 , 12 ( Figure 2); a stack 50 of electrochemical cells 10 ( Figure 3); and stack 50 compressed between endplates 17, 18 ( Figure 4).
  • Figures 1 -4 each also illustrate manifolds 30 for delivering and removing reactants and products to and from the fuel cells during operation.
  • a separate cooling stream is desirable because such fuel cell stacks tend to operate at higher temperatures and produce more liquid water.
  • a separate coolant stream therefore, provides better control of the conditions of the fuel cell stack during operation but requires additional balance of plant components, such as a coolant reservoir and pumps, as well as additional maintenance.
  • a bipolar flow field plate is formed by joining two flow field plates together, namely, an anode flow field plate and a cathode flow field plate, so that an anode flow field is formed on one surface of the anode flow field plate while a cathode flow field is formed on one surface of the cathode flow field plate.
  • a coolant flow field is formed between opposing surfaces of the anode flow field plate and the cathode flow field plate when the anode and cathode plates are bonded, glued or welded together to form a bipolar flow field plate.
  • the coolant which may be water, glycol, or a mixture thereof, is circulated as a separate stream in the coolant flow field.
  • an air-cooled fuel cell stack can be used because control of the oxidant stoichiometry and temperature of the fuel cell stack is less stringent.
  • Air-cooled stacks are desirable as they typically operate with reactants at near ambient oxidant temperatures and pressures, and do not require a separate cooling system because air is used as the oxidant and the coolant, thereby simplifying the system design.
  • Air-cooled stacks also often operate with a dead-ended anode, that is, the anode is dead- ended or closed for at least a portion of the time during operating and periodically purged to remove primarily impurities and liquid water, such as the method of operating a fuel cell as described in U.S. Patent No.
  • the cathode flow field channels are typically very large compared to the anode flow field channels to allow for a very high air stoichiometry, which also allows for sufficient cooling of the fuel cell during operation.
  • the cathode flow field channels tend to be very short, for example, running along the width of the flow field plate (i.e. , running perpendicular to the anode flow field channels) and open to air on both ends, to reduce pressure drop, which reduces the need for more powerful air blowers.
  • the bipolar flow field plate is typically a single plate that has an anode flow field on one surface and a cathode flow field on the opposing surface.
  • Flow field plates need to be electrically and thermally conductive and, therefore, typically comprise graphitic and/or metallic materials, such as graphite and stainless steels that are coated with an electrically conductive material.
  • Metal plates are desirable as they are usually made thinner than graphite plates, which is advantageous for automotive applications which require high power density, and can be easily formed by stamping such that the negative features of the anode flow field plate can be used as the positive features of the coolant flow field channels.
  • the negative features of the anode flow field plate need to be suitable as the positive features of the cathode flow field channels.
  • anode and cathode flow field channels may be running in different directions, for example, if the anode flow field channels are serpentine flow channels and the cathode flow field channels are straight flow channels, such as that shown in U.S. SIR registration number H002241 .
  • a flow field plate for an air-cooled fuel cell comprises: an anode flow field comprising a serpentine anode flow channel with a plurality of passes, wherein each pass is separated by an anode landing and each pass is fluidly connected to an adjacent pass by a recess formed in the anode landing; and an opposing cathode flow field comprising a plurality of cathode flow channels, wherein each cathode flow channel is separated by a cathode landing; wherein the anode landing of the anode flow field forms the cathode flow field channels of the cathode flow field; and a depth of the recess in the anode landing is less than a depth of the cathode flow channels.
  • the depth of the recess in the anode landing is less than half the depth of the cathode flow channel. In further embodiments, the depth of the recess in the anode landing is less than a third of the depth of the cathode flow channel. In yet further embodiments, the depth of the recess in the anode landing is less than a quarter of the depth of the cathode flow channel.
  • Figures 1 to 4 show a fuel cell stack configuration according to the prior art.
  • Figure 5 shows an isometric view of an anode flow field side of a bipolar flow field plate according to one embodiment.
  • Figure 6 shows an isometric view of a cathode flow field side of a bipolar flow field plate according to one embodiment.
  • Figure 7 shows a cross-sectional view of two bipolar flow field plates according to one embodiment.
  • a bipolar flow field plate for an air-cooled fuel cell comprises an anode flow field on one surface having a serpentine anode flow channel and a cathode flow field on the opposing surface having a plurality of cathode flow channels.
  • Figure 5 shows the anode flow field side of an exemplary bipolar flow field plate.
  • Bipolar flow field plate 100 comprises an anode flow field having serpentine flow channel 104 which is fluidly connected to fuel inlet manifold 106 via fuel feed channel 108.
  • Serpentine flow channel 104 includes a number of passes 1 10a, 1 10b, 1 10c that traverse across the width of bipolar plate 100 towards to the oxidant outlet manifold (not shown).
  • anode landings 1 12a, 1 12b, 1 12c are formed between passes 1 10a, 1 10b, 1 10c to separate each of the passes while also forming the cathode flow channels on the opposing side of bipolar flow field plate 100.
  • recesses 1 14a, 1 14b, 1 14c are formed in the end portions of anode landings 1 10a, 1 10b, 1 10c, thereby forming a single serpentine flow channel 104.
  • the depth of recesses 1 14a, 1 14b, 1 14c are less than the depth or height of anode landings 1 12a, 1 12b, 1 12c, so as not to significantly block air flow through the cathode flow channels on the opposing side of bipolar flow field plate 100.
  • the depth of the recesses or "vias" 1 14a, 1 14b, 1 14c should be such that the pressure drop of the cathode flow channels is not significantly increased.
  • the depths of recesses 1 14a, 1 14b, 1 14c are less than one half of the depth or height of anode landings 1 12a, 1 12b, 1 12c. In specific embodiments, the depths of recesses 1 14a, 1 14b, 1 14c are less than one third of the depth or height of anode landings 1 12a, 1 12b, 1 12c. In yet further embodiments, the depths of recesses 1 14a, 1 14b, 1 14c are less than one quarter of the depth or height of anode landings 1 12a, 1 12b, 1 12c. In further embodiments, the depths of recesses 1 14a, 1 14b, 1 14c are less than one eighth of the depth or height of anode landings 1 12a, 1 12b, 1 12c.
  • cathode flow channels 1 18a, 1 18b, 1 18c may be oversized to further reduce the pressure drop therein.
  • the air stoichiometry of the oxidant flowing through the cathode flow channels may range from about 10 to about 200 during fuel cell operation. While the air stoichiometry can be designed to be very high, the fuel stoichiometry is still desirably low for fuel efficiency reasons. For example, the fuel stoichiometry may range from 1 .0 to about 2.0, typically about 1 .1 to about 1 .5.
  • a serpentine anode flow channel that traverses the anode flow field is desirable to maximize the length of the anode flow channel in order to create enough pressure drop within the channel to remove impurities and liquid water, particularly when operating with a dead-ended anode. In some embodiments, a single
  • serpentine flow channel is used on the anode flow field.
  • Recesses 1 14a, 1 14b, 1 14c should be sized such that they allow for liquid water removal.
  • recesses 1 14a, 1 14b, 1 14c are not necessarily the same size.
  • the recesses near the outlet could be slightly bigger in cross-sectional area than the recesses at the inlet to help with liquid water removal at the outlet.
  • one skilled in the art will be able to determine the size of the cathode flow channels to allow for different recess sizes while reducing pressure drop in the cathode flow channels.
  • a number of fuel cells are stacked together such that the MEA is interposed between two bipolar plates.
  • the MEA is interposed between two bipolar plates.
  • the landings and channels will overlap one another and create an "egg-box" effect, which will damage the MEA due to flexure.
  • the flow field channels and landings of one flow field plate are offset with the flow field landings and channels of the adjacent flow field plate so that the MEA can be compressed without any flexural movement.
  • the anode landing aligns and overlaps with the cathode landing of the opposite plate.
  • the flow field plate is asymmetrical such that the flow field features of the flow field plate are biased towards one manifold of the plate, so that when the flow field plate is rotated 180 degrees in the x-y plane, the features of the adjacent plate will overlap one another such that the anode landing overlaps with the cathode landing of the opposite plate. This allows only one flow field plate that needs to be formed, thereby reducing production costs.
  • Flow field plate 100 may be any suitable material, such as, but not limited to, graphitic, carbonaceous, or metallic, and combinations thereof.
  • flow field plate 100 may be a stainless steel metal coated with an electrically conductive coating.
  • the advantage of using a metallic material is that the plate may be formed simply, for example but not limited to, by stamping or hydroforming.
  • flow field plate 100 may also be, for example, a graphite plate or an expanded graphite plate with molded or machined features.

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

Abstract

L'invention concerne une plaque de champ d'écoulement pour une pile à combustible refroidie par air comprenant : un champ d'écoulement d'anode comprenant un canal d'écoulement d'anode en serpentin avec une pluralité de passages, chaque passage étant séparé par un palier d'anode et chaque passage étant en communication fluidique avec un passage adjacent par un évidement formé dans le palier d'anode; et un champ d'écoulement de cathode opposé comprenant une pluralité de canaux d'écoulement de cathode, chaque canal d'écoulement de cathode étant séparé par un palier de cathode : le palier d'anode formant les canaux de champ d'écoulement de cathode; et une profondeur de l'évidement dans le palier d'anode est inférieure à une profondeur des canaux d'écoulement de cathode.
PCT/US2018/023420 2017-03-29 2018-03-20 Plaque de champ d'écoulement pour une pile à combustible électrochimique WO2018183047A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US201762478440P 2017-03-29 2017-03-29
US62/478,440 2017-03-29

Publications (1)

Publication Number Publication Date
WO2018183047A1 true WO2018183047A1 (fr) 2018-10-04

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114709439A (zh) * 2022-05-31 2022-07-05 武汉氢能与燃料电池产业技术研究院有限公司 质子交换膜燃料电池流场板

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20020081477A1 (en) * 2000-12-26 2002-06-27 Mclean Gerard F. Corrugated flow field plate assembly for a fuel cell
US20030012986A1 (en) * 2000-03-28 2003-01-16 Petra Koschany Method of operating a fuel cell system, and fuel cell system operable accordingly
US20050048351A1 (en) * 2001-11-07 2005-03-03 Hood Peter D. Fuel cell fluid flow field plates
US7153598B2 (en) 2003-03-07 2006-12-26 Ballard Power Systems Inc. Methods of operating fuel cells having closed reactant supply systems

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20030012986A1 (en) * 2000-03-28 2003-01-16 Petra Koschany Method of operating a fuel cell system, and fuel cell system operable accordingly
US20020081477A1 (en) * 2000-12-26 2002-06-27 Mclean Gerard F. Corrugated flow field plate assembly for a fuel cell
US20050048351A1 (en) * 2001-11-07 2005-03-03 Hood Peter D. Fuel cell fluid flow field plates
US7153598B2 (en) 2003-03-07 2006-12-26 Ballard Power Systems Inc. Methods of operating fuel cells having closed reactant supply systems

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114709439A (zh) * 2022-05-31 2022-07-05 武汉氢能与燃料电池产业技术研究院有限公司 质子交换膜燃料电池流场板

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