JP2007188860A - Fuel cell system with gasket having voltage detection terminal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system having a power generation part generating electric power by electrochemical reaction of hydrogen with oxygen. <P>SOLUTION: The fuel cell system contains a membrane electrode assembly containing a conductive polymer membrane having an anode layer and a cathode layer on each side of the conductive polymer membrane; a pair of separator plates facing the anode layer and the cathode layer of the membrane electrode assembly and having a flow passage through which hydrogen-containing fuel or an oxygen-containing gas supplied to the electrode layer flows; a pair of gaskets preventing fluid leakage interposed between the membrane electrode assembly and the separator plate. At least one gasket of the pair of gaskets is a voltage detecting gasket comprising a first frame of elastic material and a second frame of conductive material. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a voltage measuring means capable of measuring a voltage of an electricity generation unit during a fuel cell development process, an optimization tuning process, or during actual operation, and more specifically, prevents fluid outflow in the electricity generation unit. The present invention relates to a fuel cell system including a gasket having a voltage measurement terminal so that the voltage can be measured.

  In general, a fuel cell system is a power generation system that generates electricity, and includes an electricity generation unit that generates electricity by an electrochemical reaction between hydrogen and oxygen. The electricity generating unit has a structure in which a plurality of unit cells each including a conductive polymer film having selective ion permeability and cathode and anode electrodes provided on both sides of the polymer film are stacked. At this time, a bipolar plate for supplying hydrogen and oxygen to the anode electrode and the cathode electrode is provided between adjacent unit cells.

  Means for measuring the voltage at the electricity generator when electricity is generated by the electrochemical reaction between hydrogen and oxygen described above are well known.

  For example, Japanese Patent Laid-Open No. 2005-183308 (Patent Document 1) shows a fuel cell having a structure in which a voltage detection terminal of a voltage detection unit is in contact with a terminal connection portion of a separator, as shown in FIG. ing. In Patent Document 1, such an inert gas is supplied to the anode side electrode, while air is supplied to the cathode side electrode, and the circuit voltage of the power generation cell is detected by the voltage detection unit.

  In Japanese Patent Application Laid-Open No. 2005-019042 (Patent Document 2), as shown in FIG. 5, a flow path for cooling water is formed in a separator of a single fuel cell, and a voltage evaluation unit is formed in the separator. A fuel cell stack is disclosed that is disposed in the vicinity of the coolant flow path.

  In Japanese Patent Laid-Open No. 9-199147 (Patent Document 3), as shown in FIG. 6, an electrolyte layer is sandwiched between a fuel electrode and an oxidant electrode formed by applying a catalyst to a substrate. Disclosed is a potential measuring means for measuring a potential of at least one of a fuel electrode and an oxidant electrode of at least two unit cells in a sub-stack formed by alternately laminating a plurality of unit cells and gas separation plates. Yes.

  JP-A-8-007911 (Patent Document 4) has a structure in which the voltage measurement terminals 14 are electrically connected to the cells C at both ends of the substack Ts, as shown in FIG. It is disclosed. The voltage measurement terminal 14 is sandwiched between the cell at the end of the substack and the cooling unit 7, and is sandwiched between the cell at the end of the substack and the current collector plate 8.

In a conventional technique for measuring the voltage of a fuel cell unit cell, a method in which a pin-shaped meter-reading device is sandwiched between bipolar plates constituting a unit cell cannot guarantee stable contact, and an accurate voltage It was difficult to measure. In addition, there is a problem that the bipolar plate of the unit cell is damaged or the contact is poor as the number of times of voltage detection is increased during the development process and the tuning process.
JP 2005-183308 A JP 2005-019042 A JP-A-9-199147 JP-A-8-007911 JP 2003-123801 A

  Accordingly, an object of the present invention is to provide a fuel cell system having an electricity generation unit that generates electricity by an electrochemical reaction between hydrogen and oxygen.

  To achieve the above object, the electricity generator according to the present invention includes an electrode film assembly having a conductive polymer film having an anode electrode layer and a cathode electrode layer provided on both sides, and the electrode film. A pair of separator plates each having a flow channel through which a hydrogen-containing fuel or an oxygen-containing gas to be provided to the electrode layer faces the anode electrode layer and the cathode electrode layer of the assembly, and the electrode membrane assembly and the separator plate; A pair of gaskets interposed between the first and second gaskets to prevent fluid leakage, and at least one of the gaskets is a voltage detection gasket comprising a first frame made of an elastic material and a second frame made of a conductive material. It is characterized by that.

  The separation plate in contact with the voltage detection gasket is made of a non-conductive material.

  The first frame is in contact with a separation plate, and the second frame is in contact with a conductive polymer film.

  The second frame is provided with a voltage detection terminal.

  As described above, according to the present invention, the bipolar plate is damaged when the voltage is detected by the bipolar plate by measuring the voltage generated from the unit cell using the voltage detection gasket having the frame made of the conductive material. The voltage can be accurately detected while preventing the phenomenon.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a schematic view of a fuel cell system according to the present invention, FIG. 2 is a cross-sectional view showing a part of an electricity generator having a voltage detection gasket according to the present invention, and FIG. 3 is a voltage detection according to the present invention. It is a perspective view of a gasket.

  Referring to FIG. 1, the fuel cell system according to the present invention is provided with one or more unit cells. The electricity generator 100 generates electricity by an electrochemical reaction between hydrogen and oxygen, and the electricity generator 100 is supplied with hydrogen. A fuel supply unit 200 that supplies the contained fuel and an oxygen supply unit 300 that supplies an oxygen-containing gas to the electricity generation unit 100 are included.

  Here, the hydrogen-containing fuel means liquid raw fuel such as alcohol fuel such as methanol and ethanol, hydrocarbon fuel such as methane, propane and butane, natural gas fuel such as liquefied natural gas, or gaseous raw fuel such as hydrogen. The hydrogen can be preferably obtained from the liquid raw fuel.

  The fuel supply unit 200 may include a raw fuel supply tank (not shown) in a direct methanol fuel cell that directly supplies the liquid raw fuel to the electricity generator 100. Meanwhile, in the polymer electrolyte fuel cell that supplies gaseous raw fuel to the electricity generation unit 100, the fuel supply unit 200 includes a raw fuel storage unit (not shown) in which liquid raw fuel is stored, and the raw fuel storage unit. A reforming fuel (not shown) for supplying a reformed fuel mainly composed of hydrogen obtained through a reforming process to the liquid raw fuel supplied from the unit, that is, a gaseous raw fuel to the electricity generating unit 100 Can be configured.

  In the following, a direct methanol fuel cell will be described as a reference.

  Referring to FIG. 2, the unit cell provided in the electricity generating unit 100 includes a conductive polymer film 112 having selective ion permeability, anode electrodes 114 provided on both sides of the conductive polymer film 112, and It has an electrode membrane assembly 110 (MEA) composed of a cathode electrode 116, and an anode electrode 114 and a separator plate 130 for supplying a hydrogen-containing fuel and an oxygen-containing gas to the cathode electrode 116, respectively.

  The conductive polymer film 112 has a function of preventing permeation of hydrogen-containing fuel as well as an ion exchange function of transmitting hydrogen ions generated from a catalyst layer (not shown) of the anode electrode 114 to the catalyst layer of the cathode electrode 116. The conductive polymer electrolyte membrane has a thickness of about 50 to 200 μm. Examples of the conductive polymer film 112 include a perfluorinated sulfonic acid resin film made of perfluorosulfonate resin (Nafion (registered trademark)), a porous polytetrafluoroethylene thin film support, and a perfluorosulfonic acid ( For example, a membrane coated with a resin solution such as perfluorinated sulfide acid) or a membrane in which a porous non-conductive polymer support is coated with a cation exchange resin and an inorganic silicate is used.

In the electrode membrane assembly 110, an electrode, for example, a cathode electrode 116, includes a first porous support layer such as carbon paper, a first diffusion layer of a catalyst material sequentially stacked on the first porous support layer, and a first porous layer. 1 catalyst layer. The first porous support layer includes not only an inflow path of oxygen supplied through an oxygen supply channel 134 formed on one surface of the separation plate 130, but also the first catalyst layer as described below. Providing an outflow path for water (H ₂ O), a byproduct of the electrochemical reaction consisting of In the first catalyst layer, oxygen provided via the first porous support layer and the first diffusion layer undergoes a reduction reaction of the following reaction formula 1.
Cathode reaction:
(3/2) O ₂ + 6H ⁺ + 6e ⁻ → 3H ₂ O (1)

  The first diffusion layer is interposed between the first porous support layer and the first catalyst layer, and oxygen supplied through the oxygen supply channel 134 is uniformly dispersed in the first catalyst layer. In this way, the water generated through the reduction reaction acts to be discharged to the first porous support layer.

Similarly, the anode electrode 114 includes a second porous support layer such as carbon paper, and a second diffusion layer and a second catalyst layer of a catalyst material sequentially stacked on the second porous support layer. The second porous support layer includes not only the inflow path of the hydrogen-containing fuel supplied through the fuel supply flow path 132 formed on one surface of the separation plate 130, but also the second porous support layer as described below. It provides an outflow route for carbon dioxide (CO ₂ ), which is a byproduct of the electrochemical reaction performed in the catalyst layer. In the second catalyst layer, the hydrogen-containing fuel provided via the second porous support layer and the second diffusion layer undergoes an oxidation reaction of the following reaction formula 2.
Anode reaction:
CH ₃ OH + H ₂ O → CO ₂ + 6H ⁺ + 6e ⁻ (2)

  The second diffusion layer is interposed between the second porous support layer and the second catalyst layer, and the hydrogen-containing fuel supplied through the fuel supply channel 132 is uniformly dispersed in the second catalyst layer. In this manner, carbon dioxide generated through the oxidation reaction is discharged to the second porous support layer.

  Therefore, in the electricity generation unit 100, the anode electrode 114 generates carbon dioxide, six hydrogen ions, and electrons by the reaction between methanol and water (oxidation reaction). The hydrogen ions are transferred to the cathode electrode 116 through the polymer membrane 112, for example, a hydrogen ion exchange membrane, and the electrons are transferred to the cathode electrode 116 through the protrusions 2 of the current collector 14b. At the cathode electrode 116, hydrogen ions, electrons, and oxygen react to generate water (reduction reaction). Overall, methanol and oxygen react to produce water and carbon dioxide.

  On the other hand, in the unit cell of the electricity generating unit 100, gaskets 120A and 120B are provided between the electrode membrane assembly 100 and the separation plate 130 for preventing fluid outflow. According to the present invention, at least one gasket acts on the voltage detection gasket 120B that can detect the voltage generated in the unit cell while preventing fluid outflow. In the figure, the voltage detection gasket 120B is provided on the anode electrode side of the electrode membrane assembly 100, but is not limited thereto, and can be provided on the cathode electrode side or both sides.

  Referring to FIG. 3, the voltage detection gasket 120B includes a first frame 122 made of an elastic material and a second frame 124 made of a conductive material. The first frame and the second frames 122 and 124 include through windows 122a and 124a penetrating so that the anode electrode and the fuel supply flow path 132 of the separation plate 130 can come into surface contact, and edges that surround the through windows 122a and 124a. Part 122b, 124b. At this time, the second frame 124 is provided with a voltage detection terminal 124c extending from the edge 124b to the outside. The first frame 122 is located in contact with the separation plate 130, and the second frame 124 is located in contact with the conductive polymer film 112. This is to allow a current generated as a result of the electrochemical reaction performed in the electrode film assembly 110 to flow through the second frame 124.

  As described above, in a state where the voltage detection gasket 120B is provided on one side of the conductive polymer film 112, the general gasket 120A made of an elastic material may be formed on the other side of the conductive polymer film 112 and another separation plate. Provided between. However, the voltage detection gasket 120B according to the present invention may be provided on both side surfaces of the conductive polymer film 112.

  In the separation plate 130, a fuel supply flow path 132 through which hydrogen-containing fuel can flow is provided on one side surface facing the anode electrode 114 of the electrode membrane assembly 100, and faces the cathode electrode 116. On the other side, an oxygen supply channel 134 through which an oxygen-containing gas can flow is provided. The separator 130 is provided with a refrigerant flow channel 136 through which a refrigerant can flow in order to remove heat generated during the above-described electrochemical reaction.

  As described above, the separation plate 130 may be made of a non-conductive material with the voltage detection gasket 120B provided between the separation plate 130 and the conductive polymer membrane 112. This is because the current generated in the electrode film assembly 110 can flow to the second frame 124 of the voltage detection gasket 120B. That is, if the voltage detection gasket 120B is provided on the anode electrode 114 side of the electrode membrane assembly 110, the separation plate 130 in contact with the anode electrode 114 can be made of a non-conductive material, and the voltage detection If the gasket 120B is provided on the cathode electrode 116 side of the electrode membrane assembly 110, the separation plate 130 contacting the cathode electrode 116 can be made of a non-conductive material.

  For example, if the voltage detection gasket 120B is provided on both sides of the electrode membrane assembly 110, the hydrogen is supplied through the fuel supply channel 132 and the oxygen supply channel 134 formed in the non-conductive substance separation plate 130. The contained fuel and the oxygen-containing gas are supplied to the anode electrode 114 and the cathode electrode 116, respectively. Then, as a result of the electrochemical reaction composed of the anode electrode 114 and the cathode electrode 116, carbon dioxide and water respectively generated at the anode electrode 114 and the cathode electrode 116 are discharged to the outside through the non-conductive substance separation plate 130. Is done. In this way, when the separator 130 is made of a non-conductive material, the manufacturing cost can be reduced.

  In the fuel cell system having the electricity generation unit having the above-described structure, the voltage of each unit cell is measured during the development process, the optimization tuning process, or the actual operation to determine whether the unit is operating normally. That is, a voltage detector (not shown) is brought into contact with the voltage detection terminal 124c provided on the second frame of the voltage detection gasket 120B to measure the voltage per unit cell. The voltage detector generally includes a voltage detection unit that is connected to the voltage detection terminal 124c so as to be energized, and a voltage display unit that measures the voltage of the unit battery detected by the voltage detection unit.

  Hereinafter, the operation of the fuel cell system according to the present invention will be described.

  A low concentration hydrogen-containing fuel, for example, methanol having a predetermined concentration diluted with water is supplied to the electricity generation unit 100 from the fuel supply unit 200. In the electricity generating unit 100, it is easily supplied to the unit cell, particularly the anode electrode 114 of the electrode membrane assembly 110, via the fuel supply channel 132 of the separation plate 130. Oxygen supplied from the oxygen supply unit 300 is supplied from the electricity generation unit 100 to the unit cell, in particular, the cathode electrode 116 of the electrode membrane assembly 110 via the oxygen supply channel 134 of the separation plate 130.

  In the anode electrode 114, the hydrogen-containing fuel provided via the second porous support layer and the second diffusion layer is oxidized in the second catalyst layer, and as a result, hydrogen ions, electrons, and carbon dioxide are generated. The At this time, hydrogen ions move to the first catalyst layer of the cathode electrode 116 through the conductive polymer membrane 112, and carbon dioxide passes through the second porous support layer to the fuel supply channel of the separation plate 130. It is discharged to the outside through 132.

  In the cathode electrode 116, oxygen provided through the first porous support layer and the first diffusion layer reacts with hydrogen ions in the first catalyst layer, and as a result, water is generated. The water is discharged to the outside through the oxygen supply channel 134 of the separation plate 130 via the first porous support layer.

  At this time, the voltage detection unit of the voltage measuring device is brought into contact with the voltage detection terminal 124c to measure the voltage generated in the unit cell during the above-described electrochemical reaction. Whether each unit battery is operating normally is determined according to the magnitude of the voltage measured by the voltage measuring device.

  The above description merely exemplifies a preferred embodiment of the present invention, and those skilled in the art to which the present invention belongs will not depart from the spirit and scope of the present invention described in the appended claims. It can be appreciated that modifications and changes can be made to the present invention.

1 is a schematic view of a fuel cell system according to the present invention. It is sectional drawing which shows a part of electricity generation part which has the voltage detection gasket by this invention. It is a perspective view of the voltage detection gasket by this invention. It is a figure which shows the state by which the voltage detection terminal was provided to the separator by a prior art. 1 is a cross-sectional view of a conventional fuel cell stack. 1 is a cross-sectional view of a conventional fuel cell stack. 1 is a cross-sectional view of a conventional fuel cell stack.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Electricity generation part 200 Fuel supply part 300 Oxygen supply part 112 Conductive polymer film 114 Anode electrode 116 Cathode electrode 120A, 120B Gasket 122 1st frame 124 2nd frame 122a, 124a Through window 122b, 124b Edge part 124c Voltage detection terminal 130 Separator plate 134 Oxygen supply channel 136 Refrigerant flow channel

Claims (8)

In a fuel cell system having an electricity generation unit that generates electricity by an electrochemical reaction between hydrogen and oxygen,
The electricity generator is
An electrode film assembly having a conductive polymer film having an anode electrode layer and a cathode electrode layer respectively provided on both sides;
A pair of separator plates each having a flow channel through which a hydrogen-containing fuel or an oxygen-containing gas flows to face the anode electrode layer and the cathode electrode layer of the electrode membrane assembly and to provide the electrode layer;
A pair of gaskets interposed between the electrode membrane assembly and the separation plate to prevent fluid leakage,
At least one of the gaskets is a voltage detection gasket comprising a first frame made of an elastic material and a second frame made of a conductive material.   The fuel cell system according to claim 1, wherein the voltage detection gasket is provided with a voltage detection terminal.   The fuel cell system according to claim 2, wherein the voltage detection terminal is provided in the second frame.   The fuel cell system according to claim 3, wherein the second frame is in contact with the conductive polymer membrane, and the first frame is in contact with a separation plate.   The fuel cell system according to claim 4, wherein the voltage detection gasket is provided adjacent to the anode electrode layer.   The fuel cell system according to claim 4, wherein the voltage detection gasket is provided adjacent to the cathode electrode layer.   The fuel cell system according to claim 1, wherein the separation plate is provided with a refrigerant flow channel through which a refrigerant can flow.   The fuel cell system according to claim 1, wherein the separation plate in contact with the voltage detection gasket is made of a non-conductive material.

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