WO2011052650A1 - Pile à combustible - Google Patents

Pile à combustible Download PDF

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Publication number
WO2011052650A1
WO2011052650A1 PCT/JP2010/069092 JP2010069092W WO2011052650A1 WO 2011052650 A1 WO2011052650 A1 WO 2011052650A1 JP 2010069092 W JP2010069092 W JP 2010069092W WO 2011052650 A1 WO2011052650 A1 WO 2011052650A1
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WIPO (PCT)
Prior art keywords
fuel
catalyst layer
anode
cathode
thickness
Prior art date
Application number
PCT/JP2010/069092
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English (en)
Japanese (ja)
Inventor
宏晃 若松
千草　尚
勝美 市川
仁 甲田
小野寺　真一
北澤　祐介
直之 高澤
信一 上林
Original Assignee
株式会社 東芝
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Publication of WO2011052650A1 publication Critical patent/WO2011052650A1/fr

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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
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/1004—Fuel cells with solid electrolytes characterised by membrane-electrode assemblies [MEA]
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/90—Selection of catalytic material
    • H01M4/92—Metals of platinum group
    • 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
    • H01M8/0247—Collectors; Separators, e.g. bipolar separators; Interconnectors characterised by the form
    • 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]
    • 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

  • Embodiments of the present invention relate to a fuel cell, and particularly to a small liquid fuel direct supply type fuel cell.
  • methanol is oxidatively decomposed at an anode (for example, a fuel electrode) to generate carbon dioxide, protons, and electrons.
  • anode for example, a fuel electrode
  • the cathode for example, the air electrode
  • water is generated by oxygen obtained from air
  • electrons supplied from the fuel electrode through an external circuit for example, power is supplied by electrons passing through the external circuit.
  • Patent Document 1 discloses that the thickness of a catalyst layer using polyethersulfone as a binder and the thickness of a gas diffusion layer of the catalyst layer are defined.
  • Patent Document 2 discloses that the thickness of the catalyst layer using polyvinylidene fluoride as a binder and the thickness of the gas diffusion layer of the catalyst layer are defined.
  • Patent Document 3 uses a cathode catalyst layer in which a plurality of layers having different ratios of the mass of the polymer electrolyte to the mass of the conductive support are laminated along the direction of the gas diffusion layer from the polymer electrolyte membrane, and the average of the anode catalyst layer A fuel cell membrane electrode assembly having a thickness smaller than the average thickness of the cathode catalyst layer is disclosed.
  • Patent Document 4 discloses a fuel cell membrane-electrode assembly in which the average thickness of the anode catalyst layer is smaller than the average thickness of the cathode catalyst layer.
  • FIG. 2 The internal perspective sectional view showing the fuel cell concerning an embodiment.
  • the perspective view which shows the fuel distribution mechanism of the fuel cell of FIG. FIG. 2 is a schematic cross-sectional view showing a main part of the fuel cell of FIG. 1.
  • Embodiment aims at providing the fuel cell excellent in output performance.
  • a fuel cell including a membrane electrode assembly including an anode, a cathode, and an electrolyte membrane
  • the anode includes an anode catalyst layer and an anode gas diffusion layer provided facing one surface of the anode catalyst layer.
  • the cathode includes a cathode catalyst layer and a cathode gas diffusion layer provided facing one surface of the cathode catalyst layer.
  • the electrolyte membrane is disposed between the anode catalyst layer and the cathode catalyst layer.
  • the anode catalyst layer and the cathode catalyst layer have a noble metal weight density of 0.2 g / cc or more and 0.8 g / cc or less, and satisfy the following formula (1).
  • T a is the thickness of the anode catalyst layer.
  • a fuel cell excellent in output performance can be provided.
  • FIG. 1 is an internal perspective sectional view showing a fuel cell according to an embodiment
  • FIG. 2 is a perspective view showing a fuel distribution mechanism of the fuel cell of FIG. 1
  • FIG. 3 is a diagram of the fuel cell of FIG. It is a cross-sectional schematic diagram which shows the principal part.
  • the fuel cell 100 includes a membrane electrode assembly 1, a fuel storage unit 3 that stores liquid fuel F, a flow path 4 that connects the fuel supply unit 2 and the fuel storage unit 3, a fuel introduction unit 30, and a fuel introduction unit.
  • a fuel supply unit 2 that supplies fuel to the unit 30 and an oxidant introduction unit (oxygen introduction unit) 40 are provided.
  • the membrane electrode assembly 1 includes an anode (fuel electrode) 5, a cathode (air electrode) 6, and a proton conductive electrolyte membrane 7 disposed between the anode 5 and the cathode 6.
  • the anode 5 has an anode catalyst layer 8 provided facing one surface of the electrolyte membrane 7 and an anode gas diffusion layer 9 laminated on the anode catalyst layer 8.
  • the cathode 6 has a cathode catalyst layer 11 provided facing the other surface of the electrolyte membrane 7 and a cathode gas diffusion layer 12 laminated on the cathode catalyst layer 11.
  • the electrolyte membrane 7 contains a proton conductive material, such as a fluorine-based resin having a sulfonic acid group (trade name Nafion (registered trademark) manufactured by DuPont or Flemion (registered trademark) manufactured by Asahi Glass Co., Ltd.). Perfluorosulfonic acid polymer, etc.), hydrocarbon resins having a sulfonic acid group, inorganic substances (for example, tungstic acid, phosphotungstic acid, lithium nitrate, etc.) are used, but are not limited thereto.
  • a proton conductive material such as a fluorine-based resin having a sulfonic acid group (trade name Nafion (registered trademark) manufactured by DuPont or Flemion (registered trademark) manufactured by Asahi Glass Co., Ltd.).
  • Perfluorosulfonic acid polymer, etc.) hydrocarbon resins having a sulfonic acid group
  • inorganic substances
  • the anode gas diffusion layer 9 and the cathode gas diffusion layer 12 can be formed from, for example, a paper, a nonwoven fabric, a woven fabric, a knitted fabric, or a conductive porous film made of a fiber such as carbon or a conductive polymer. However, it is preferably formed from carbon paper. Any gas diffusion layer may be provided with water repellency or may not be provided with water repellency. For the water repellent treatment, a fluorine resin such as polytetrafluoroethylene (PTFE) can be used.
  • PTFE polytetrafluoroethylene
  • the anode gas diffusion layer 9 serves to uniformly supply fuel to the anode catalyst layer 8 and also serves as a current collector for the anode catalyst layer 8.
  • the cathode gas diffusion layer 12 serves to uniformly supply the oxidant to the cathode catalyst layer 11 and also serves as a current collector for the cathode catalyst layer 11.
  • the anode catalyst layer 8 includes an anode catalyst and a polymer electrolyte such as a perfluoropolysulfonic acid polymer electrolyte.
  • the cathode catalyst layer 11 includes a cathode catalyst and a polymer electrolyte such as a perfluoropolysulfonic acid polymer electrolyte.
  • the anode catalyst and the cathode catalyst contain a noble metal.
  • the noble metal for example, a single metal such as Pt, Ru, Rh, Ir, Os, and Pd, which is a platinum group element, an alloy containing a platinum group element, or the like is used.
  • Pt—Ru and Pt—Mo having strong resistance to methanol and carbon monoxide are suitable as the anode side catalyst
  • platinum, Pt—Ni, Pt—Co and the like are suitable as the cathode side catalyst.
  • the present invention is not limited to these. Either a supported catalyst using a conductive support such as a carbon material or an unsupported catalyst can be used.
  • particulate carbon such as activated carbon or graphite, or fibrous carbon can be used.
  • a perfluoropolysulfonic acid polymer electrolyte for example, a perfluoropolysulfonic acid polymer electrolyte can be used.
  • Perfluoropolysulfonic acid-based polymer electrolytes can use fluorine-based resins having sulfonic acid groups. Specifically, the product name Nafion (registered trademark) manufactured by DuPont and the product name Flemion (produced by Asahi Glass Co., Ltd.) Perfluorosulfonic acid polymers such as (registered trademark).
  • the perfluoropolysulfonic acid polymer electrolyte is used to bind the catalyst to the gas diffusion layer and to conduct protons generated by the electrochemical reaction.
  • perfluoropolysulfonic acid-based polymer electrolytes increase the proton conductivity of the electrode and contribute to the improvement of output performance.
  • a rubber O-ring 15 is disposed between the electrolyte membrane 7 and the cover plate 16 and between the electrolyte membrane 7 and the fuel supply unit 2 so as to surround the periphery of the membrane electrode assembly (MEA) 1. These prevent fuel leakage and oxidant leakage.
  • the oxidant introduction part (oxygen introduction part) 40 has a function of taking in an oxidant such as air from the outside and supplying it to the MEA 1 and is adjacent to the air electrode gas diffusion layer 12 from the exterior (for example, a cover plate) of the fuel cell.
  • the oxidant introduction part 40 includes a member arranged in this manner.
  • the oxidant introduction unit 40 includes, for example, the conductive layer 13 provided to face the cathode gas diffusion layer 12, the moisturizing layer 18, and the cover plate 16, but is not limited to this configuration. In addition, the configuration without the conductive layer 13 and the moisture retaining layer 18 can be obtained.
  • the conductive layer 13 is provided as necessary.
  • a porous layer for example, a mesh
  • a foil body made of a metal material such as gold or nickel, or a conductive metal material such as stainless steel (SUS) is made of gold.
  • a composite material coated with a highly conductive metal such as is used.
  • the moisture retaining layer 18 is disposed between the cover plate 16 and the cathode 6 as necessary.
  • the moisturizing layer 18 is impregnated with a part of the water generated in the cathode catalyst layer 11 to suppress the transpiration of water and has a function of diffusing a part of the generated water to the anode side.
  • the cathode gas diffusion layer also has a function of uniformly introducing air as an oxidant to promote uniform diffusion of the oxidant to the cathode catalyst layer 11.
  • the moisturizing layer 18 is composed of a flat plate made of, for example, a polyethylene porous film.
  • the cover plate 16 has a plurality of through holes 16a as openings for taking in air as an oxidant.
  • the cover plate 16 adjusts the intake amount of air, and the adjustment is performed by changing the number and size of the air inlets. It also plays a role of increasing the adhesion by pressurizing the MEA and the moisturizing layer.
  • the cover plate 16 can be made of a metal such as SUS304, but is not limited thereto. By providing such a cover plate 16, the oxidant can be naturally supplied to the cathode 6 without using a blower for supplying the oxidant. Note that the oxidizing agent is not limited to air, and a gas containing O 2 can be used.
  • a fuel distribution mechanism 2 as a fuel supply unit is disposed on the anode 5 side of the membrane electrode assembly 1.
  • the fuel supply unit 2 has a fuel discharge port facing the fuel intake surface of the fuel introduction unit 40, and supplies fuel to the fuel introduction unit 40 through the fuel discharge port.
  • the fuel distribution mechanism 2 is connected to the fuel storage unit 3 through a flow path 4 of liquid fuel F such as piping. Liquid fuel F is introduced into the fuel distribution mechanism 2 from the fuel storage portion 3 through the flow path 4.
  • the flow path 4 is not limited to piping independent of the fuel distribution mechanism 2 and the fuel storage unit 3. For example, when the fuel distribution mechanism 2 and the fuel storage unit 3 are stacked and integrated, a flow path of the liquid fuel F that connects them may be used.
  • the fuel distribution mechanism 2 only needs to be connected to the fuel storage unit 3 via the flow path 4.
  • the mechanism for feeding the liquid fuel F from the fuel storage unit 3 to the fuel distribution mechanism 2 is not particularly limited.
  • the liquid fuel F can be dropped from the fuel storage unit 3 to the fuel distribution mechanism 2 and fed by gravity.
  • the flow path 4 filled with a porous body or the like the liquid can be fed from the fuel storage portion 3 to the fuel distribution mechanism 2 by a capillary phenomenon.
  • liquid feeding from the fuel storage unit 3 to the fuel distribution mechanism 2 may be performed by a pump 17 as shown in FIG.
  • a fuel cutoff valve may be arranged instead of the pump 17. In this case, the fuel cutoff valve is provided to control the supply of the liquid fuel F through the flow path.
  • the pump 17 functions as a supply pump that simply supplies liquid fuel from the fuel storage unit 3 to the fuel distribution mechanism 2, and functions as a circulation pump that circulates excess liquid fuel supplied to the fuel cells. It does not provide.
  • the fuel cell equipped with this pump does not circulate the fuel, so the configuration is different from the conventional active method, and the configuration is different from the pure passive method such as the conventional internal vaporization type, so-called semi-passive type. Applicable.
  • the type of the pump that functions as the fuel supply means is not particularly limited, but a rotary vane pump that can feed a small amount of liquid fuel with good controllability and can be reduced in size and weight, It is preferable to use an electroosmotic pump, a diaphragm pump, a squeezing pump, or the like.
  • the rotary vane pump feeds liquid by rotating wings with a motor.
  • the electroosmotic flow pump uses a sintered porous body such as silica that causes an electroosmotic flow phenomenon.
  • a diaphragm pump drives a diaphragm with an electromagnet or piezoelectric ceramics to send liquid.
  • the squeezing pump presses a part of a flexible fuel flow path and squeezes the fuel.
  • the pump is electrically connected to the control means (not shown), and the supply amount of the liquid fuel supplied to the fuel supply unit is controlled by the control means.
  • the fuel distribution mechanism 2 includes at least one fuel injection port 21 into which the liquid fuel F flows through the flow path 4 and a plurality of fuel exhausts that discharge the liquid fuel F and its vaporized components.
  • a fuel distribution plate 23 having an outlet 22 is provided.
  • the fuel distribution plate 23 is provided with a gap 24 serving as a liquid fuel passage guided from the fuel inlet 21.
  • the plurality of fuel discharge ports 22 are directly connected to gaps 24 that function as fuel passages.
  • the fuel distribution plate 23 is made of, for example, a vaporized component of liquid fuel or a material that does not allow liquid fuel to permeate. Specifically, for example, polyethylene terephthalate (PET) resin, polyethylene naphthalate (PEN) resin, polyimide resin, and the like. Consists of.
  • PET polyethylene terephthalate
  • PEN polyethylene naphthalate
  • polyimide resin polyimide resin
  • the liquid fuel F introduced into the fuel distribution mechanism 2 from the fuel inlet 21 enters the gap portion 24 and is led to the plurality of fuel discharge ports 22 through the gap portion 24 functioning as the fuel passage.
  • a gas-liquid separator (not shown) that transmits only the vaporized component of the liquid fuel and does not transmit the liquid component may be disposed in the plurality of fuel discharge ports 22.
  • the vaporized component of the liquid fuel is supplied to the anode 5 of the membrane electrode assembly 1.
  • the vaporized component of the liquid fuel is discharged from a plurality of fuel discharge ports 22 toward a plurality of locations of the fuel introduction unit 30.
  • a plurality of fuel discharge ports 22 are provided on the surface of the fuel distribution plate 23 facing the fuel introduction portion 30 so that fuel can be supplied to the entire membrane electrode assembly 1.
  • the number of the fuel discharge ports 22 may be two or more. However, in order to equalize the fuel supply amount in the surface of the membrane electrode assembly 1, the fuel discharge ports 22 of 0.1 to 10 / cm 2 are provided. It is preferable to form it so that it exists.
  • the liquid fuel F introduced into the fuel distribution mechanism 2 described above is guided to the plurality of fuel discharge ports 22 via the gaps 24. Since the gap 24 of the fuel distribution mechanism 2 functions as a buffer, fuel of a specified concentration is discharged from the plurality of fuel discharge ports 22. Since the plurality of fuel discharge ports 22 are arranged so that fuel is supplied to the entire surface of the membrane electrode assembly 1, the amount of fuel supplied to the membrane electrode assembly 1 can be made uniform.
  • the liquid storage unit 3 stores the liquid fuel F corresponding to the membrane electrode assembly 1.
  • the liquid fuel F include methanol fuels such as methanol aqueous solutions having various concentrations and pure methanol.
  • the liquid fuel F is not necessarily limited to methanol fuel.
  • the liquid fuel F may be, for example, an ethanol fuel such as an ethanol aqueous solution or pure ethanol, a propanol fuel such as a propanol aqueous solution or pure propanol, a glycol fuel such as a glycol aqueous solution or pure glycol, dimethyl ether, formic acid, or other liquid fuel.
  • the liquid fuel F corresponding to the membrane electrode assembly 1 is stored in the fuel storage portion 3.
  • the type and concentration of liquid fuel are not limited. However, the characteristic of the fuel distribution mechanism 2 having a plurality of fuel discharge ports 22 becomes more apparent when the fuel concentration is high. For this reason, the fuel cell can particularly exhibit its performance and effects when a methanol aqueous solution or pure methanol having a concentration of 80% or more is used as the liquid fuel.
  • the fuel introduction unit 30 has a function of supplying the fuel discharged from the fuel discharge port 22 of the fuel distribution mechanism 2 to the MEA 1, and a member disposed between the anode gas diffusion layer 9 and the fuel distribution mechanism 2 is provided. It is included in this fuel introduction part 30.
  • the fuel introduction part 30 is provided to face the fuel electrode gas diffusion layer 9 and has a fuel intake surface in contact with the fuel discharge port 22 of the fuel distribution mechanism 2.
  • the fuel intake surface refers to the surface on the fuel discharge port 22 side of the layer in contact with the fuel discharge port 22 of the fuel distribution mechanism 2.
  • the present invention is not limited to this, and the fuel diffusion layer 19 may not be included, or other layers may be included.
  • the conductive layer 14 is provided as necessary.
  • a porous layer for example, a mesh
  • a foil body made of a metal material such as gold or nickel, or a conductive metal material such as stainless steel (SUS) is made of gold.
  • a composite material coated with a highly conductive metal such as is used.
  • the fuel diffusion layer 19 has a surface in contact with the fuel discharge port 22 of the fuel supply unit 2 and plays a role of uniformly diffusing the fuel discharged from the fuel discharge port 22 to the anode 5 as vaporized fuel.
  • the fuel released from the fuel distribution mechanism 2 is introduced into the MEA 1 via the fuel introduction unit 30.
  • the fuel diffuses through the anode gas diffusion layer 9 and is supplied to the anode catalyst layer 8.
  • an internal reforming reaction of methanol shown in the following formula (A) occurs.
  • the fuel cell described above includes an anode catalyst layer, an anode having an anode gas diffusion layer provided facing one side of the anode catalyst layer, a cathode catalyst layer, and one of the cathode catalyst layer.
  • a membrane electrode assembly is provided that includes a cathode having a cathode gas diffusion layer provided facing the surface, and an anode catalyst layer and an electrolyte membrane disposed between the cathode catalyst layer.
  • the anode catalyst layer and the cathode catalyst layer have a noble metal weight density of 0.2 g / cc or more and 0.8 g / cc or less, and satisfy the following formula (1).
  • T a is the thickness of the anode catalyst layer.
  • the weight density of at least one of the anode catalyst layer and the cathode catalyst layer is 0.2 g / cc or more. It has been found that when the amount is 0.8 g / cc or less, both the initial output and the output retention rate of the fuel cell are improved.
  • the catalyst amount of at least one of the anode catalyst layer and the cathode catalyst layer becomes sufficient.
  • the output can be improved.
  • the noble metal weight density of at least one of the anode catalyst layer and the cathode catalyst layer 0.8 g / cc or less the fuel diffusion efficiency or the air intake efficiency is improved, so that the initial output and the output maintenance ratio are improved. Can do.
  • both the anode catalyst layer and the cathode catalyst layer when the noble metal weight density of both the anode catalyst layer and the cathode catalyst layer is 0.2 g / cc or more and 0.8 g / cc or less, the amount of catalyst in both the anode catalyst layer and the cathode catalyst layer becomes sufficient. Since both the fuel diffusion efficiency and the air intake efficiency are improved, the initial output and the output maintenance rate can be greatly improved.
  • a more preferable range of the noble metal weight density ( ⁇ a) in the anode catalyst layer is 0.5 g / cc or more and 0.7 g / cc or less.
  • a more preferable range of the catalyst noble metal weight density ( ⁇ c) in the cathode catalyst layer is 0.3 g / cc or more and 0.6 g / cc or less.
  • the upper limit value of (T a / T c ) is desirably 7. By setting the value of (T a / T c ) to 7 or less, the thickness of the anode catalyst layer relative to the cathode catalyst layer becomes appropriate, and fuel diffusion proceeds smoothly, so that sufficient output can be obtained. it can.
  • the upper limit value of (T a / T c ) is more preferably 4.25. By setting the amount to 4.25 or less, it is possible to avoid a relatively small amount of the catalyst on the cathode, thereby improving the life characteristics.
  • the noble metal weight density ( ⁇ a) of the anode catalyst layer is 0.2 g / cc or more and 0.8 g / cc or less, and the cathode satisfies the following formula (2).
  • the cathode By setting the value of the ratio of (T c / C d ) to 0.1 or more when the noble metal weight density ( ⁇ a) of the anode catalyst layer is 0.2 g / cc or more and 0.8 g / cc or less, the cathode Thus, both the initial output and the output retention ratio can be further improved by the synergistic effect of the cathode and the anode.
  • the value of the ratio (T c / C d ) 0.5 or less, so-called flooding in which H 2 O generated by the power generation reaction becomes liquid water and covers the cathode gas diffusion layer is prevented. Therefore, the air intake efficiency is improved, and both the initial output and the output maintenance rate can be further improved.
  • the cathode thickness C d is desirably 250 ⁇ m or 400 ⁇ m or less. As a result, the initial output and the output maintenance ratio can be further improved.
  • the noble metal weight density of the cathode catalyst layer is 0.2 g / cc or more and 0.8 g / cc or less, and the anode satisfies the following formula (3).
  • T a 0.1 ⁇ (T a / A d ) ⁇ 0.6 (3)
  • T a the thickness of the anode catalyst layer.
  • both the initial output and the output retention ratio can be further improved by the synergistic effect of the cathode and the anode.
  • the value of (T a / A d ) is 0.6 or less, it is possible to increase both the proton conductive ability of the anode catalyst layer and the gas diffusion ability of the anode gas diffusion layer. It is possible to suppress the fuel efficiency. As a result, both the initial output and the output maintenance rate can be further improved.
  • the thickness A d of the anode is preferably not less than 330 [mu] m 650 .mu.m or less. As a result, the initial output and the output maintenance ratio can be further improved.
  • the thickness T e of the electrolyte membrane is preferably not more than 180 [mu] m.
  • the total thickness of T M and the thickness A f of the fuel introduction part 30 (hereinafter referred to as cell thickness T) is not particularly limited, but can be 700 ⁇ m or more and 900 ⁇ m or less.
  • the fuel cell according to the present embodiment is not limited to the structure shown in FIGS. 1 to 3, and can be configured as shown in FIG. 4, for example. Members similar to those described in FIGS. 1 to 3 are denoted by the same reference numerals and description thereof is omitted.
  • the fuel diffusion layer 19 of the fuel introduction unit 30 includes a diffusion sheet (product name Sunmap manufactured by Nitto Denko) 51, a gas-liquid separation membrane 52, and a polytetrafluoroethylene (PTFE) membrane 53 in this order from the fuel supply unit 2 side. Are stacked.
  • the conductive layer 14 is laminated on the PTFE film 53.
  • the surface of the diffusion sheet 51 is in contact with the fuel discharge port 22 of the fuel supply unit 2.
  • the gas-liquid separation membrane separates the vaporized component of the liquid fuel and the liquid fuel, and passes the vaporized component to the anode (fuel electrode) side.
  • This gas-liquid separation membrane is made of a material that is inert to liquid fuel and does not dissolve, and is formed into a sheet.
  • silicone rubber low-density polyethylene (LDPE) thin film, polyvinyl chloride (PVC) thin film, polyethylene
  • LDPE low-density polyethylene
  • PVC polyvinyl chloride
  • It is made of a material such as a terephthalate (PET) thin film, a fluororesin (for example, polytetrafluoroethylene (PTFE), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), etc.), or a microporous film.
  • the gas-liquid separation membrane is configured so that fuel and the like do not leak from the periphery.
  • the PTFE membrane suppresses the permeation of water vapor and prevents an excessive amount of water vapor from being supplied to the anode.
  • a resin frame (not shown) may be provided between the gas-liquid separation membrane and the anode.
  • the space surrounded by the frame functions as a vaporized fuel storage chamber (so-called vapor pool) that temporarily stores the vaporized fuel that has diffused through the gas-liquid separation membrane, and also functions as a reinforcing plate that tightly contacts the membrane electrode assembly To do. Due to the effect of suppressing the amount of permeated methanol in the vaporized fuel storage chamber and the gas-liquid separation membrane, it is possible to avoid supplying a large amount of vaporized fuel to the anode catalyst layer at once.
  • the frame is a short frame, and is made of engineering plastic having high chemical resistance such as polyetheretherketone (PEEK: trademark of Victorex).
  • the oxidant introduction unit 40 has a multilayer structure in which the conductive layer 13, the PTFE film 54, the moisture retention layer 18, the reinforcing plate 55, and the cover plate 56 are laminated in this order from the cathode 6 side.
  • the reinforcing plate 55 and the cover plate 56 are made of, for example, SUS, and each has a plurality of openings (not shown) for taking in air as an oxidant.
  • the PTFE membrane 54 is impregnated with a part of the water generated in the cathode catalyst layer 11 to suppress the transpiration of water and promote the uniform diffusion of air to the cathode catalyst layer 11.
  • the thickness of each component is measured by the following method.
  • the precious metal weight and the precious metal weight density are measured by the following methods.
  • the MEA cut out for measuring the amount of noble metal is first peeled off to the anode and the cathode. Next, the whole area is cut out to 2 cm 2 and placed in a container, 250 mL of a hydrochloric acid / nitric acid mixed solution is added, and a thermal decomposition treatment is performed at 140 ° C. for 2 hours.
  • the cut-out from the MEA is the central portion in the planar direction of each cell.
  • the obtained heat-decomposed liquid is subjected to (xmL) ICP measurement (pressure acid decomposition-ICP emission spectroscopy).
  • ICP measurement pressure acid decomposition-ICP emission spectroscopy.
  • IRIS Advantage manufactured by Thermo Fisher Scientific Co., Ltd. was used.
  • the measurement conditions are as shown below.
  • the amount of noble metal in the sample (y / X) ⁇ 250.
  • a precious metal weight per unit area (mg / cm 2 ) is calculated from the obtained precious metal amount ( ⁇ g) and the sample area.
  • the fuel cell applicable to the embodiment has a liquid fuel and an oxidant from its form. Active type fuel cell that supplies the fuel using an auxiliary device such as a pump, a passive type (internal vaporization type) fuel cell that supplies a vaporized component of liquid fuel to the anode, and a semi-passive type fuel cell shown in FIG. It is done.
  • the active fuel cell employs a system in which a fuel made of an aqueous methanol solution is supplied to the anode of the MEA while being adjusted by a pump so that the amount thereof is constant, and air is also supplied to the cathode by a pump.
  • a fuel made of an aqueous methanol solution is supplied to the anode of the MEA while being adjusted by a pump so that the amount thereof is constant, and air is also supplied to the cathode by a pump.
  • the passive type fuel cell a system in which vaporized methanol is naturally supplied to the anode of the MEA and natural air is also supplied to the cathode and no extra equipment such as a pump is provided.
  • the fuel supplied from the fuel storage part to the membrane electrode assembly is used for the power generation reaction, and is not circulated thereafter and returned to the fuel storage part.
  • the semi-passive type fuel cell is different from the active method because it does not circulate the fuel, and does not impair the downsizing of the device. Further, the semi-passive type fuel cell uses a pump for supplying fuel, and is different from a pure passive type such as an internal vaporization type. In this semi-passive type fuel cell, a fuel cutoff valve may be arranged in place of the pump as long as fuel is supplied from the fuel storage portion to the membrane electrode assembly. In this case, the fuel cutoff valve is provided to control the supply of liquid fuel through the flow path.
  • the fuel cell according to the embodiment described above is effective when various liquid fuels are used, and the type and concentration of the liquid fuel are not limited. Further, the above-described embodiment has been described by taking a semi-passive type using a pump for supplying fuel as an example of the configuration of the fuel cell main body, but for a purely passive type fuel cell such as an internal vaporization type However, the present invention can be applied.
  • Example 1 ⁇ Production of anode> A platinum-supporting carbon (carbon carrier: ketjen black, platinum content: 50% by mass) particles 8%, a perfluorosulfonic acid polymer composed of DE2020 (manufactured by DuPont), and a solvent are mixed by a homogenizer to obtain about 20 A slurry with a% solid content was prepared, and this was applied to one side of a compressed carbon paper (TGP-H-120 manufactured by Toray Industries, Inc.) as an anode gas diffusion layer using a die coater. This was dried at room temperature to form an anode catalyst layer.
  • a compressed carbon paper TGP-H-120 manufactured by Toray Industries, Inc.
  • MEA membrane electrode assembly
  • the membrane electrode assembly was sandwiched between gold foils having a plurality of apertures for taking in air and vaporized methanol to form an anode conductive layer having a thickness of 60 ⁇ m and a cathode conductive layer having a thickness of 60 ⁇ m.
  • the laminated body in which the membrane electrode assembly (MEA), the anode conductive layer, and the cathode conductive layer were laminated was sandwiched between two resin frames.
  • a rubber O-ring was sandwiched between the cathode side of the membrane electrode assembly and one frame, and between the anode side of the membrane electrode assembly and the other frame, respectively.
  • the anode side frame was fixed to the liquid fuel storage chamber with a screw through a gas-liquid separation membrane.
  • a 0.2 mm thick silicone sheet was used for the gas-liquid separation membrane.
  • a porous plate having a porosity of 28% and a thickness of 750 ⁇ m was arranged to form a moisture retaining layer.
  • a stainless steel plate (SUS304) having a thickness of 2 mm with air inlets (4 mm diameter, 64 holes) for air intake is arranged to form a cover plate, and screwed Fixed.
  • Pure water is injected into the liquid fuel storage chamber of the fuel cell formed as described above while controlling the cathode temperature to 55 ° C. with a pump.
  • the initial output and the output retention rate were measured by the following method, and the results are shown in Table 1 below.
  • Pure methanol having a purity of 99.9% by weight was supplied to the fuel cell produced as described above in an environment where the temperature was 25 ° C. and the relative humidity was 50%.
  • a constant voltage power supply is connected to control the current flowing through the fuel cell so that the output voltage of the fuel cell becomes constant at 0.35 V (per 1 MEA).
  • the output density obtained from the fuel cell is controlled.
  • the output density (mW / cm 2 ) of the fuel cell is obtained by multiplying the current density flowing through the fuel cell (current value per 1 cm 2 area of the power generation unit (mA / cm 2 )) by the output voltage of the fuel cell.
  • the initial output is an average of the output density of 10 to 20 hours from the start of power generation.
  • the output maintenance ratio is obtained by dividing the output density after 1000 hours by the initial output in%.
  • each constituent member is measured by the method described above, and the cell thickness T, the catalyst layer thickness ratio (T a / T c ), the cathode thickness ratio (T c / C d ), and the anode
  • the thickness ratio (T a / A d ) is also shown in Table 1 below.
  • the oxygen introducing section 40 has a cover plate, the moisture retaining layer, the conductive layer and the frame, the thickness C o of the oxygen introduction part 40 was 1710Myuemu.
  • the cathode thickness C d is 310 .mu.m
  • the anode having a thickness of A d is 470 ⁇ m
  • 50 ⁇ m thickness of the electrolyte membrane T e the thickness T M of the membrane electrode assembly was 830 microns.
  • the fuel introduction part 30 had a gas-liquid separation membrane, a conductive layer, and a frame, and the thickness A f of the fuel introduction part 30 was 450 ⁇ m.
  • Example 2 By changing the thickness of the cathode catalyst layer and the anode catalyst layer by changing the pressing conditions during MEA fabrication, the cell thickness T, the noble metal weight density, the catalyst layer thickness ratio (T a / T c ), A fuel cell was manufactured in the same manner as in Example 1 except that the cathode thickness ratio (T c / C d ) and the anode thickness ratio (T a / A d ) were changed as shown in Table 1 below. . The initial output and output retention rate of the obtained fuel cell were measured under the same conditions as in Example 1, and the results are shown in Table 1 below.
  • Example 10 An attempt was made to produce a membrane electrode assembly including an anode having a catalyst layer thickness ratio (T a / T c ) of 1.55 and an anode catalyst layer having a noble metal weight density of 0.889 g / cc. At this time, the anode catalyst layer was destroyed, and a membrane electrode assembly could not be obtained.
  • T a / T c catalyst layer thickness ratio
  • the weight density of at least one of the cathode catalyst layer and the anode catalyst layer is 0.2 g / cc or more and 0.8 g / cc or less, and the thickness ratio (T a / T c ) is
  • Examples 1 to 8 have an initial output or an output maintained as compared with Example 9 in which the noble metal weight density of the anode catalyst layer is within the above range but the thickness ratio (T a / T c ) is less than 1. It can be seen that the rate is high and the output performance is excellent.
  • Example 1 to Example 5 in which the noble metal weight density of both the cathode catalyst layer and the anode catalyst layer is 0.2 g / cc to 0.8 g / cc It can be seen that both are superior to Examples 6 and 7 in which the noble metal weight density of only one of the cathode catalyst layer and the anode catalyst layer satisfies the above range.
  • Example 1 the cathode thickness ratio (T c / C d ) and the anode thickness ratio (T a / A d ) satisfy the expressions (2) and (3).
  • both the initial output and the output retention ratio are superior to Example 8 (the cathode thickness ratio (T c / C d ) does not satisfy the formula (2)). Recognize.
  • the present invention can be applied to various fuel cells using liquid fuel. Further, the specific configuration of the fuel cell, the supply state of the fuel, and the like are not particularly limited.
  • the constituent elements can be modified and embodied without departing from the technical idea of the present invention. Furthermore, various modifications are possible, such as appropriately combining a plurality of constituent elements shown in the above embodiment, or deleting some constituent elements from all the constituent elements shown in the embodiment.
  • Embodiments of the present invention can be expanded or modified within the scope of the technical idea of the present invention, and these expanded and modified embodiments are also included in the technical scope of the present invention.
  • SYMBOLS 1 Membrane electrode assembly (MEA), 2 ... Fuel supply part (fuel distribution mechanism), 3 ... Fuel accommodating part, 4 ... Flow path, 5 ... Anode, 6 ... Cathode, 7 ... Electrolyte membrane, 8 ... Anode catalyst layer , 9 ... Anode gas diffusion layer, 11 ... Cathode catalyst layer, 12 ... Cathode gas diffusion layer, 13 ... Cathode conductive layer, 14 ... Anode conductive layer, 15 ... O-ring, 16 ... Cover plate, 16a ... Opening, 17 ... Pump, 18 ... moisturizing layer, 21 ... fuel inlet, 22 ... fuel outlet, 23 ... fuel distribution plate, 24 ... gap, 30 ... fuel inlet, 40 ... oxidant inlet, 100 ... fuel cell.
  • MEA Membrane electrode assembly
  • 2 Fuel supply part (fuel distribution mechanism), 3 ... Fuel accommodating part, 4 ... Flow path, 5 ... Anode, 6 ... Cathode,

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Abstract

La présente invention concerne une pile à combustible pourvue d'un ensemble électrode à membrane comprenant l'anode, la cathode, et une membrane d'électrolyte. L'anode comprend une couche de catalyseur d'anode, et une couche de diffusion de gaz d'anode agencée en face d'une surface de la couche de catalyseur d'anode. La cathode comprend une couche de catalyseur de cathode, et une couche de diffusion de gaz de cathode agencée en face d'une surface de la couche de catalyseur de cathode. La membrane d'électrolyte est disposée entre la couche de catalyseur d'anode et la couche de catalyseur de cathode. La densité massique du métal noble dans la couche de catalyseur d'anode et/ou la couche de catalyseur de cathode est de 0,2 à 0,8 g/cc, et les couches de catalyseur satisfont à l'inégalité suivante : 1 ≤ (Ta/Tc) (1), avec Tc l'épaisseur de la couche de catalyseur de cathode et Ta l'épaisseur de la couche de catalyseur d'anode.
PCT/JP2010/069092 2009-10-28 2010-10-27 Pile à combustible WO2011052650A1 (fr)

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US20200295381A1 (en) * 2017-10-03 2020-09-17 Vito Nv Carbon Based Electrode with Large Geometric Dimensions
CN111886733A (zh) * 2018-03-29 2020-11-03 凸版印刷株式会社 膜电极接合体及固体高分子型燃料电池

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WO2006006607A1 (fr) * 2004-07-13 2006-01-19 Matsushita Electric Industrial Co., Ltd. Pile à combustible électrolytique polymère
JP2008041474A (ja) * 2006-08-08 2008-02-21 Gs Yuasa Corporation:Kk 直接メタノール形燃料電池用膜／電極接合体およびそれを用いた直接メタノール形燃料電池
WO2008143020A1 (fr) * 2007-05-14 2008-11-27 Nec Corporation Pile à combustible de type polymère à l'état solide
JP2009076451A (ja) * 2007-08-24 2009-04-09 Toshiba Corp 燃料電池用電極膜接合体およびそれを用いた燃料電池
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Cited By (3)

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Publication number Priority date Publication date Assignee Title
US20200295381A1 (en) * 2017-10-03 2020-09-17 Vito Nv Carbon Based Electrode with Large Geometric Dimensions
US11962019B2 (en) * 2017-10-03 2024-04-16 Vito Nv Carbon based electrode with large geometric dimensions
CN111886733A (zh) * 2018-03-29 2020-11-03 凸版印刷株式会社 膜电极接合体及固体高分子型燃料电池

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