JP2008153040A - Fuel cell, fuel cell system, and control method of fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell, a fuel cell system equipped with the fuel cell, and a control method of the fuel cell system. <P>SOLUTION: The fuel cell is at least provided with an electrolyte layer, an anode electrode as well as a cathode electrode opposed to each other pinching the electrolyte layer, a collector, and a separator. The collector has a laminated structure consisting of two or more layers containing at least a high-resistance layer forming one of the surfaces and a low-resistance layer with a resistance value lower than the high-resistance layer and forming the other surface, the collector and the anode electrode and/or the cathode electrode are in contact with each other directly or through a conductive member. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel cell, a fuel cell system including the fuel cell, and a control method for the fuel cell system, and more particularly, to a direct methanol fuel cell, a fuel cell system including the fuel cell, and a control method for the fuel cell system. About.

  In recent years, as a power source for portable electronic devices that support the information society, there is an increasing expectation for a fuel cell because it has high power generation efficiency and high energy density as a single power generation device. The fuel cell electrochemically oxidizes and reduces a reducing agent such as hydrogen and methanol at the anode electrode and an oxidant such as oxygen in the air at the cathode electrode, and generates electricity through this oxidation and reduction reaction.

  Among various fuel cell systems, a direct methanol fuel cell (hereinafter also referred to as “DMFC”) that generates electricity by directly extracting protons from methanol does not require a reformer, and Since liquid methanol having a higher volumetric energy density than gas fuel is used, the methanol fuel container can be made smaller than when a high-pressure gas cylinder represented by hydrogen is used. Therefore, DMFC has been attracting attention in terms of application to power supplies for small devices, particularly secondary battery replacement for portable devices.

  In addition, since the fuel of DMFC is liquid, it is possible to use a narrow curved space part, which was a dead space in the conventional fuel cell system, as a fuel space. It has the merit that it can be used for electronic equipment.

  FIG. 21 is a cross-sectional view showing the structure of a conventional fuel cell. As shown in FIG. 21, a fuel cell generally includes a structure (membrane electrode assembly, hereinafter simply referred to as MEA) in which an electrolyte layer 1 is sandwiched between an anode electrode 2 and a cathode electrode 3 as a pair of conductive separators. In each separator, each of the separators has a serial stack structure arranged as shown in FIG. 21 so that one side is the anode side and the other side is the cathode side. Generally, a flow path 8 and a cathode fuel flow path 9 are provided, and an extraction electrode 5 and, if necessary, a heater 7 are generally provided at the end of the stack structure. The above-described stack structure is pressed by a casing 6 or an end plate of the cell using fastening members such as bolts and nuts from both sides of the stack structure, thereby reducing contact resistance and maintaining the stack structure.

  In a general solid polymer fuel cell, a polymer film such as a Nafion (registered trademark) film, a sulfonated polyimide film, an inorganic solid polymer, or an inorganic-organic hybrid polymer film is used as an electrolyte layer. Electrodes are integrated and attached to both surfaces by hot pressing, and a diffusion layer (for example, carbon paper, carbon cloth, etc.) for diffusing fuel is attached to the catalyst layer. As the electrode, a catalyst layer generally composed of catalytic metal-supported carbon particles and an ion conductive polymer binder, for example, a catalyst layer composed of platinum-supported carbon or platinum-ruthenium-supported carbon and Nafion binder is used. It is done.

  For example, hydrogen, methanol or the like is supplied as a reducing agent to the anode electrode, and oxygen or the like is supplied as an oxidizing agent to the cathode electrode from a flow path provided in the separator. In a fuel cell, electrons are taken out from the oxidation-reduction reaction that occurs at each of the anode and cathode electrodes and used as direct current electric energy. A structure that exchanges electrons with an electrode and collects and flows electrons is generally defined as a current collector. A structure that separates the anode and the cathode is generally defined as a separator. An electrolyte layer is also included in the separator.

  Conventionally, in a fuel cell, there is a problem that power generation efficiency is significantly reduced at low temperatures. The cause is mainly a decrease in ionic conductivity of the electrolyte layer, a decrease in catalytic activity, and the like. When the outside air temperature is low, for example, when the outside air temperature is below the freezing point, it takes time until a predetermined output characteristic is obtained particularly at the time of startup. Further, there is a problem that the fuel cell deteriorates when the outside air temperature becomes below freezing point when the fuel cell is stopped. In a polymer electrolyte layer using proton as a carrier, the proton conductivity is proportional to the number of cation exchange groups in the polymer constituting the polymer electrolyte layer. There is a large amount. Since this cation exchange group adsorbs moisture, there is a considerable amount of moisture in the polymer electrolyte layer. Below the freezing point, this moisture freezes and causes volume expansion, which causes deterioration of the fuel cell.

  As a countermeasure to the above problem, as described in Patent Document 1, a technique for supplying electric power to an external load of a fuel cell and improving startability by self-heating is proposed. In addition, as described in Patent Document 2, a fuel cell stack is sandwiched and heated by an insulating plate equipped with a PTC heater, thereby improving startability and protecting the temperature after stopping, Patent As described in Document 3, a technique for improving startability by locally heating a fuel cell with a heater and promoting self-heating is also proposed. Also, as described in Patent Document 4, a technique has been proposed in which a portion having a high resistance value is provided at the end of the current collector plate and the temperature of the cell at the end is improved.

Fuel cells are required to improve power generation efficiency not only at start-up but also during steady operation. In order to improve power generation efficiency, the MEA that is the power generation unit, that is, the anode electrode, cathode electrode, and electrolyte layer portions It is preferable to raise the temperature of the material within a range not exceeding the pressure resistance of the material. On the other hand, in recent years, miniaturization of fuel cells is also required. However, in the conventional fuel cell and stack as described above, it is difficult to achieve both startability and power generation efficiency by improving the heating efficiency of the electrode and the electrolyte layer, and downsizing of the fuel cell. Currently.
JP 2000-512068 A JP-A-5-89900 JP 2002-313391 A JP 2003-45462 A

  An object of the present invention is to solve the above problems and to provide a fuel cell capable of improving startability and power generation efficiency and downsizing, a fuel cell system including the fuel cell, and a control method for the fuel cell system. To do.

  The present invention includes at least an electrolyte layer, an anode electrode and a cathode electrode facing each other with the electrolyte layer interposed therebetween, a current collector, and a separator, and the current collector includes a high resistance layer forming one surface, And a low-resistance layer having a lower resistance value than that of the high-resistance layer and forming the other surface, and a laminated structure comprising two or more layers, and the current collector, the anode electrode, and / or Alternatively, the present invention relates to a fuel cell in which the cathode electrode is in direct contact with or through a conductive member.

  The fuel cell of the present invention preferably has a laminated structure in which an anode-side current collector, an anode electrode, an electrolyte layer, a cathode electrode, and a cathode-side current collector are laminated in this order.

  The fuel cell of the present invention preferably has a laminated structure in which an anode electrode, an anode current collector, an electrolyte layer, a cathode current collector, and a cathode electrode are laminated in this order.

  In the present invention, the low resistance layer of the current collector is preferably in contact with the anode electrode and / or the cathode electrode directly or through a conductive member.

  In the present invention, the layers other than the low resistance layer in the current collector are preferably electrically connected to the anode electrode or the cathode electrode only through the low resistance layer.

  In the present invention, two or more layers constituting the current collector are laminated with each other through only an insulating layer in a region where the anode electrode or cathode electrode is formed, and the anode electrode or cathode electrode is not formed. It is preferable that at least a part of the region is electrically connected.

  In the present invention, each layer constituting the current collector preferably has a take-out portion for taking out current.

  In the present invention, the current collector is formed between the electrolyte layer and the anode electrode and / or the cathode electrode, and layers other than the low resistance layer of the current collector are formed with the anode electrode and / or the cathode electrode. It is preferable that the region is covered with an insulating layer.

In the present invention, the insulating layer is preferably made of a porous body.
In the present invention, it is preferable that the current collector and the electrolyte layer are integrated by joining the insulating layer and the electrolyte layer.

In the present invention, the insulating layer is preferably made of an electrolyte material.
The fuel cell of the present invention preferably further includes a heater.

  The present invention is also a fuel cell system for driving a load, wherein any one of the above-described fuel cells and a switch unit for controlling the presence or absence of energization to two or more layers constituting the current collector A temperature sensor for detecting at least one of the temperature of the anode and / or cathode electrode of the fuel cell and the outside air temperature, and a control unit for controlling the switch unit based on the detection result of the temperature sensor, The present invention relates to a fuel cell system.

  The present invention is also a fuel cell system for driving a load, wherein any one of the above-described fuel cells and a switch unit for controlling the presence or absence of energization to two or more layers constituting the current collector And a monitor unit for detecting the output current and / or output voltage of the fuel cell, and a control unit for controlling the switch unit based on the detection result of the monitor unit.

In the fuel cell system of the present invention, the current collector is provided on the anode side and the cathode side of the fuel cell, and the current collector on the anode side and the cathode side includes a high resistance layer and a low resistance layer,
The switch unit includes first and second switch elements for electrically connecting the load and the high resistance layer and the low resistance layer on the anode side, and the load and the high resistance layer and the low resistance layer on the cathode side. It is preferable to include a third and a fourth switch element for electrical connection.

  The fuel cell system of the present invention preferably further includes a power storage device and a charge / discharge circuit for the power storage device.

  The present invention is also a control method of the above-described fuel cell system, wherein the temperature sensor detects at least one of the temperature of the anode and / or cathode electrode of the fuel cell and the outside air temperature, and based on the detection result. And a step of controlling the switch unit by the control unit to energize a layer other than the low resistance layer in the current collector, and by passing a current through the layer other than the low resistance layer, the anode electrode and / or the cathode electrode The present invention relates to a control method of a fuel cell system for increasing temperature.

  In the energizing step, energizing layers other than the low resistance layer in the current collector when the temperature of the anode electrode and / or cathode electrode or the outside air temperature is lower than a predetermined temperature based on the detection result. Is preferred.

  According to the present invention, the temperature difference obtained by subtracting the temperature of the anode electrode from the temperature of the cathode electrode based on the detection result is detected in advance in the step of detecting and detecting the temperature of the anode electrode and the cathode electrode in the detecting step. The present invention relates to a control method for a fuel cell system in which a current other than a low resistance layer in a current collector is energized when lower than a predetermined value.

  The present invention is also a control method for the fuel cell system described above, wherein the monitor unit detects the output current and / or output voltage of the fuel cell, and the output current and / or output voltage is determined based on the detection result. By controlling the switch unit by the control unit and energizing a layer other than the low-resistance layer in the current collector when lower than a predetermined value set in advance, and by passing a current through the layer other than the low-resistance layer The present invention relates to a method for controlling a fuel cell system, which raises the temperature of an anode electrode and / or a cathode electrode.

  In the control method of the fuel cell system of the present invention, current collectors are provided on the anode side and the cathode side of the fuel cell, and the current collectors on the anode side and the cathode side are composed of a high resistance layer and a low resistance layer, The switch unit includes first and second switch elements for electrically connecting the load and the high resistance layer and the low resistance layer on the anode side, and the load and the high resistance layer and the low resistance layer on the cathode side. And electrically conducting the high resistance layer in the energizing step by conducting the first and third switch elements, respectively. .

  According to the present invention, it is possible to provide a fuel cell having improved startability and power generation efficiency and capable of being downsized, a fuel cell system including the fuel cell, and a control method for the fuel cell system.

  The fuel cell of the present invention includes at least an electrolyte layer, an anode electrode and a cathode electrode facing each other with the electrolyte layer interposed therebetween, a current collector, and a separator. Further, the current collector provided in the fuel cell of the present invention comprises a high resistance layer forming one surface, and a low resistance layer having a lower resistance value than the high resistance layer and forming the other surface. It has a laminated structure composed of at least two layers including at least a current collector, and the anode electrode and / or the cathode electrode are in direct contact with each other through a conductive member. In the following description of the present invention, the “anode electrode and / or cathode electrode” is also simply referred to as “electrode” unless otherwise specified.

  When a current is passed through the high resistance layer of the current collector, the current collector itself can generate heat due to resistance loss, and the fuel cell can be heated. On the other hand, the low resistance layer of the current collector is excellent in function as an extraction electrode that collects current generated from the fuel cell from the electrode. In the fuel cell of the present invention having a current collector including at least a high resistance layer and a low resistance layer, for example, by switching a circuit, a current is allowed to flow in either or both of the high resistance layer and the low resistance layer. Can be easily set. Therefore, for example, when the outside air temperature decreases or when the fuel cell starts, the temperature of the fuel cell, particularly in the vicinity of the electrode and the electrolyte layer, is quickly increased by passing a current through the high resistance layer. During normal operation, By using the resistance layer for current collection from the electrode so that a current flows through the low resistance layer, it is possible to obtain excellent startability and power generation efficiency.

  In the present invention, since the current collector functioning as the extraction electrode is also used as the heating element, the structure of the fuel cell can be simplified, and a smaller fuel cell can be obtained.

  That is, for example, a heater typified by a heating wire generally applies a voltage to cause a current to flow and generates heat due to resistance loss. Therefore, when such a heater is brought into direct contact with the electrode, a voltage is applied to the electrode. In addition, the fuel cell may be enlarged to provide a heater. On the other hand, when external heat such as a chemical reaction or heat of a semiconductor element is used, the internal structure of the cell is complicated by the conductor for guiding the heat, and the cell becomes large. On the other hand, according to the configuration of the fuel cell of the present invention, it is possible to efficiently heat the MEA with a simple and small configuration by causing the current collector itself to generate heat.

  In the present invention, the current collector and the electrode are formed so as to be in contact directly or via a conductive member. That is, it has the characteristic that the distance between the electrode and the electrolyte layer and the current collector is relatively short. The current collector functions as an extraction electrode for the fuel cell and is made of a conductive material. Since a material having high conductivity generally has a low thermal resistance, in the present invention, the current collector is connected to the electrode with a low thermal resistance. For example, as compared with the case of heating with a heater or the like, the electrode and the electrolyte layer are connected. The heat transfer efficiency is extremely excellent.

  In addition, when the current for energizing the current collector cannot be secured from the fuel cell at the time of starting the fuel cell of the present invention, a current is passed from the external power source such as a secondary battery or a capacitor to the current collector, By raising the temperature of the electrolyte layer instantaneously, the fuel cell can be started early and output power can be taken out from the fuel cell.

  1 and 2 are cross-sectional views showing an example of a configuration in which a plurality of cells are connected in the fuel cell of the present invention. The fuel cells 100 and 200 include an electrolyte layer 101, an anode electrode 102a and a cathode electrode 102b facing each other with the electrolyte layer interposed therebetween, current collectors 103, 104, and 105, and a separator 106. The current collectors 103, 104, and 105 are formed so as to be in contact with the anode electrode 102a and the cathode electrode 102b. The fuel cell 100 is also provided with an anode fuel channel 107a, a cathode fuel channel 107b, and heaters 109a and 109b. The current collectors 103, 104, and 105 have a laminated structure including two or more layers, but are simplified in FIGS. In addition, since the site | part to which the same referential mark is attached | subjected in this invention has the same function, description is not repeated about each drawing.

  FIG. 1 shows a structure in which a fuel cell includes an insulating separator 106, cells are connected in series, and are stacked in the layer thickness direction. FIG. 2 shows a structure in which cells are stacked vertically and horizontally in a plane direction. 1 and 2, from two or more layers including at least a high resistance layer forming one surface and a low resistance layer having a lower resistance value than the high resistance layer and forming the other surface. The case where the current collector having the laminated structure is provided on both the anode side and the cathode side is shown. However, in the present invention, it suffices if a current collector having the above characteristics is provided on at least one of the anode side and the cathode side.

  As shown in FIG. 1, the fuel cell of the present invention may further include diffusion layers 108 a and 108 b outside the current collectors 103, 104, and 105. In the present invention, the diffusion layer may be formed between the current collector and the electrode as the conductive member in the present invention.

  The fuel cell of the present invention may have a structure as shown in FIG. 1 in which a plurality of unit cells of the fuel cell are stacked in the layer thickness direction, or FIG. 2 in which a plurality of unit cells are stacked vertically and horizontally in the plane direction. A known stack structure may be employed.

  When the fuel cell of the present invention has a stack structure, a current collector composed of two or more layers including at least a high resistance layer and a low resistance layer may be provided in all of the unit cells and forms both ends of the stack structure. You may provide only in a unit cell. Further, the current collector may be provided at intervals of every other unit cell in the stack structure. In the planar stack structure as shown in FIG. 2, the current collector is preferably provided in a unit cell that forms the peripheral edge of the stack structure, particularly in a unit cell that forms four corners of the stack structure.

  When the current collector is provided in all the unit cells, the electrodes and the electrolyte layer can be heated more uniformly and efficiently.

  In addition, when the current collector is provided only in a part of the unit cell, for example, in the above-described manner, the electrodes and the electrolyte layer can be heated relatively uniformly and with high efficiency, and power for heat generation can be obtained. Consumption can be kept low, and the power generation efficiency of the fuel cell can be improved.

  The fuel cell of the present invention may further include a heater as long as the effects of the present invention are not impaired. In this case, the electrode and the electrolyte layer can be heated more rapidly by the combination with the current collector formed in the present invention. In this case, the heater is preferably provided in the cell surrounded by the separator, that is, in the unit cell of the fuel cell in terms of heating efficiency. Specifically, the heater is insulated from the current collector, It is preferable to provide between the separators, inside the electrodes, or adjacent to both the electrodes and the separators.

  In the present invention, when the current collector is in direct contact with the anode electrode and / or the cathode electrode, the heat conduction from the current collector to the electrode is particularly good, and the temperature of the electrode and the electrolyte layer can be increased efficiently. Is preferable in that it is possible. FIG. 1 shows a case where current collectors 103, 104, and 105 are in direct contact with anode electrode 102a and cathode electrode 102b, respectively.

  On the other hand, in the present invention, a conductive member may be interposed between the current collector and the anode electrode and / or the cathode electrode. Examples of the conductive member include a diffusion layer made of carbon or the like. The diffusion layer functions to supply fuel and discharge carbon dioxide between the current collector and the anode electrode at the anode electrode. Further, the cathode electrode functions to supply an oxidant represented by oxygen between the current collector and the cathode electrode and to discharge generated water.

  1 and 2, for example, the fuel cell of the present invention has a laminated structure in which an anode-side current collector, an anode electrode, an electrolyte layer, a cathode electrode, and a cathode-side current collector are laminated in this order. It is preferable. In this case, since the current collector is in contact with the electrode, the heat conduction from the current collector to the electrode is good, and the heat dissipated to the outside is small, so that the temperature of the electrode and electrolyte layer can be raised with low power consumption I can do it. Thereby, the startability of the fuel cell can be improved, and the power generation efficiency can be improved by improving ion conductivity and catalytic activity. Moreover, since the diffusion coefficient of fuel, air, by-products and various ions increases as the temperature in the vicinity of the electrode increases, the energy density can be improved by reducing the diffusion resistance of each substance, and the power generation efficiency can be further improved. it can.

  The fuel cell of the present invention preferably has a laminated structure in which an anode electrode, an anode current collector, an electrolyte layer, a cathode current collector, and a cathode electrode are laminated in this order. In this case, since the current collector is located between the electrode and the electrolyte layer, it is possible to efficiently raise the temperature of the electrode and the electrolyte layer. In addition, since the current collector is sandwiched between the electrode and the electrolyte layer, the adhesive force between the current collector, the electrode and the electrolyte layer is improved, and the adhesion can be further improved and the contact resistance can be further reduced. It is.

  In the present invention, it is preferable that the low-resistance layer of the current collector is in contact with the anode electrode and / or the cathode electrode directly or through a conductive member to collect current at the low-resistance layer. In this case, loss of heat generated by resistance when supplying power from the fuel cell to an external device can be reduced, and power can be efficiently extracted. In addition, when a current flows through the current collector, a voltage drop due to resistance occurs, and unevenness in potential distribution and output current density occurs on the electrode surface, so the catalyst in the electrode is locally loaded and the catalyst deteriorates. However, when the current is collected in the low resistance layer portion, the voltage drop due to the resistance can be prevented, so that the deterioration of the catalyst can be satisfactorily prevented.

  In the present invention, layers other than the low resistance layer of the current collector may be provided so as to be insulated from the anode electrode or the cathode electrode, but layers other than the low resistance layer of the current collector are low. It is preferable to be electrically connected to the anode electrode or the cathode electrode only through the resistance layer. In this case, heat generated when a current is passed through a layer other than the low resistance layer can be supplied to the electrode as close as possible through the low resistance layer. Further, it is possible to prevent a potential distribution due to a voltage drop generated when a current is passed through the portion of the layer having a higher resistance than the low resistance layer from being applied to the electrode, and to prevent deterioration of the catalyst in the electrode.

  In the present invention, the layers other than the low resistance layer of the current collector are covered with, for example, an insulating layer, so that each layer of the current collector is laminated only through the insulating layer in the region where the electrode is formed. In at least a part of the region where the electrode is not formed, it is also preferable that layers other than the low resistance layer are electrically connected to the anode electrode or the cathode electrode only through the low resistance layer. In this case, deterioration of the catalyst in the electrode can be satisfactorily prevented.

  In this case, it is preferable to provide a current extraction portion (ie, an extraction terminal) in each layer constituting the current collector, so that not only the low resistance layer but also a layer other than the low resistance layer can be used as the extraction electrode. Can do. In this case, it is preferable to provide the extraction portion so as to face the connection portion between the layer other than the low resistance layer and the low resistance layer with the middle point of the connection portion between the electrode and the current collector interposed therebetween. It is preferable to provide the extraction portion in a region other than the connection portion between the electrode and the current collector. Thereby, the structure which a layer other than the low resistance layer of an electrical power collector and a collector does not contact directly can be formed reliably.

  It is also preferable that the current collector is formed between the electrolyte layer and the electrode, and in the region where the electrode is formed, a layer other than the low resistance layer of the current collector is covered with an insulating layer. Also in this case, deterioration of the catalyst in the electrode can be prevented particularly well.

  When a layer other than the low resistance layer is electrically connected to the electrode only through the low resistance layer, heating of the fuel cell by flowing current through the layer other than the low resistance layer of the current collector After switching the circuit so that a current flows through this layer, the output terminal of the fuel cell can be short-circuited. Even if the output terminal of the fuel cell is short-circuited, the potential difference between the anode and cathode of each fuel cell does not become close to 0 due to the presence of layers other than the low resistance layer, and excessive overvoltage is applied to the catalyst. Therefore, there is an advantage that the catalyst does not deteriorate. Note that the resistance value of the layers other than the low resistance layer is such that the output current that flows at the time of a short circuit does not deteriorate the catalyst due to the overvoltage of the electrode, and a sufficient output current flows for heating the electrode and the electrolyte. It is preferable to select as follows.

  In the present invention, the resistance value of the current collector is preferably uniform (that is, uniform) in the planar direction. In this case, the current flow becomes uniform, and the heat generation in the current collector becomes uniform. As a result, heating of the electrode and the electrolyte layer can be performed uniformly to prevent local improvement in the catalytic ability of the electrode and the ionic conductivity in the electrolyte layer, and unevenness of the output current of the electrode and potential distribution can be prevented. Deterioration of the electrolyte layer and the catalyst due to a typical temperature rise can be satisfactorily prevented.

  Hereinafter, a more detailed example of the structure of the fuel cell of the present invention will be described with reference to the drawings by taking a direct methanol fuel cell as an example, but the present invention is not limited to this. In the following, a case of a so-called direct methanol (direct methanol type) fuel cell in which an aqueous methanol solution having a predetermined concentration of 3 mol / L is used for the anode fuel and oxygen in the air is used for the cathode will be described as an example.

<Electrolyte layer>
The electrolyte layer can be formed of a conventionally known appropriate polymer film, inorganic film, or composite film. Examples of the polymer membrane include perfluorosulfonic acid electrolytes such as Nafion (registered trademark) (DuPont), Dow membrane (Dow Chemical), Aciplex (Asahi Kasei) and Flemion (Asahi Glass). Examples thereof include hydrocarbon electrolyte layers such as layers, polystyrene sulfonic acid, and sulfonated polyether ether ketone. Examples of the inorganic film include phosphate glass, cesium hydrogen sulfate, polytungstophosphoric acid, ammonium polyphosphate, and the like. Examples of the composite membrane include a Gore Select membrane (manufactured by Gore) and a pore filling electrolyte layer.

The proton conductivity of the electrolyte layer is preferably 10 ⁻⁵ S / cm or more, and more preferably 10 ⁻³ S / cm or more. The electrolyte layer having a proton conductivity of 10 ⁻³ S / cm or more can be formed by a polymer electrolyte layer such as a perfluorosulfonic acid polymer or a hydrocarbon polymer.

<Anode electrode and cathode electrode>
In the present invention, the anode electrode means a site where a substance supplied from the outside causes a chemical reaction to generate protons and electrons, and the cathode electrode means a substance supplied from the outside that converts protons and electrons. It means a site that takes up, causes a chemical reaction, and produces water. The anode electrode and the cathode electrode are typically constituted by an anode catalyst layer and a cathode catalyst layer.

  The anode electrode can typically be composed of an anode catalyst layer including carbon particles supporting anode catalyst particles and a solid polymer electrolyte. In addition, the cathode electrode can typically be composed of a cathode catalyst layer including carbon particles supporting cathode catalyst particles and a solid polymer electrolyte. In the anode electrode, the anode catalyst particles have a function of generating carbon dioxide, protons, and electrons from methanol, and the solid polymer electrolyte has a function of conducting the protons generated above to the electrolyte layer. The carbon particles have a function of conducting the electrons generated above to the anode current collector. In the cathode electrode, the cathode catalyst particles have a function of generating water from oxygen, protons, and electrons, and the solid polymer electrolyte has a function of conducting protons from the electrolyte layer to the vicinity of the cathode catalyst particles. Has a function of conducting electrons from the cathode conductive layer in the vicinity of the cathode catalyst particles.

  Examples of the carbon particles include acetylene black (for example, XC72 (manufactured by Vulcan)), ketjen black, amorphous carbon, carbon nanotube, carbon nanohorn, and the like.

  Examples of the catalyst for forming the anode catalyst particles and the cathode catalyst particles include noble metals such as Pt, Ru, Au, Ag, Rh, Pd, Os, Ir, Ni, V, Ti, Co, Mo, Fe, Cu, and Zn. Base metals such as are exemplified. These can be used alone or in combination of two or more. In addition, the kind of catalyst contained in an anode catalyst layer and a cathode catalyst layer is not necessarily limited to the same kind, A different kind of catalyst can be used.

  The polymer electrolyte has a function of electrically connecting the carbon particles carrying the catalyst between them (ie, electronically) and physically connecting the carbon particles to the electrolyte layer, as well as hydrogen ion conduction. Function, water mobility and oxygen permeability are required. Therefore, specifically, the polymer electrolyte is preferably an organic polymer having a strong acid group such as a sulfone group or a phosphoric acid group or a weak acid group such as a carboxyl group. Examples of the organic polymer include sulfonic acid group-containing perfluorocarbon (Nafion (manufactured by DuPont)), carboxyl group-containing perfluorocarbon (for example, Flemion (manufactured by Asahi Kasei)), polystyrene sulfonic acid copolymer, and polyvinyl sulfonic acid copolymer. , Etc. are exemplified.

  The thicknesses of the anode electrode and the cathode electrode are preferably 0.1 mm or less, respectively, from the viewpoint that the resistance of proton conduction and the resistance of electronic conduction can be reduced and methanol or oxygen can be supplied to the inside. It is preferable that it is 0.1 micrometer or more at the point which can improve an output voltage by obtaining a sufficient catalyst load.

<Current collector>
The current collector formed in the present invention has a function as an extraction electrode and a function as a heating element, and is typically made of metal. In the present invention, the current collector includes at least two of a high resistance layer forming one surface and a low resistance layer having a resistance value lower than that of the high resistance layer and forming the other surface. Consists of layers. The low resistance layer is a conductive layer having the lowest sheet resistance among the layers forming the current collector. The resistance value of each layer constituting the current collector can be controlled by the metal material and shape. The current collector is preferably one having a hole processed in the flat plate, particularly a one having a through hole formed therein, or a mesh-like one in that the resistance value can be easily increased or decreased. It is preferable to adjust the resistance value by controlling the aperture ratio, thickness, aperture, and the like of the current collector. Thereby, the resistance value can be set easily and inexpensively.

  In the present invention, the current collector is formed so as to be in contact with the anode electrode and / or the cathode electrode directly or via a conductive member. When the current collector is provided on either the anode side or the cathode side, for example, at least one element selected from the group consisting of Ti, Ta, Au, Ag, Pt, Nb, Ni, Si, W, and Al is used. It is preferable to include. By including these elements, the specific resistance of the current collector that functions as the extraction electrode is reduced, so that the resistance loss of the extraction electrode can be reduced and the power generation efficiency can be improved. Further, as the current collector, a stainless alloy may be used, and SUS316L, NSSC270, etc., which are sulfuric acid-resistant stainless steel, are more preferable.

  A current collector composed of two or more layers having different resistance values can be designed by changing the material and shape of each layer. In addition, as a high resistance layer and / or a low resistance layer forming the surface of the current collector, it is preferable to use a metal mesh or a stamped metal plate that has been subjected to conductive corrosion resistance treatment.

  Further, when corrosion of the current collector becomes a problem, Au having corrosion resistance that does not elute metal ions on the surface of the current collector in an acidic aqueous solution atmosphere or oxygen atmosphere and does not form a non-conductive layer, You may coat noble metals, such as Pt, Pd, and Ru, and the conductive resin which consists of carbon, carbon, and resin. Thereby, there is no possibility that metal ions eluted in the electrolyte and the electrolyte layer in the anode electrode and cathode electrode described later are mixed into the current collector. Furthermore, since a non-conductive layer is not formed on the current collector surface, long-term reliability of the MEA can be obtained.

  Further, the thickness of the current collector varies depending on the value of the specific resistance of the metal material to be used. However, in order to suppress a voltage drop as the wiring, the thickness is preferably 100 μm or more in the case of a plate shape. Further, when the current collector has a mesh shape, the wire diameter is preferably 100 μm or more.

  When using a metal mesh or stamped metal plate as the current collector, the current collector is provided with openings in the layer thickness direction for supplying fuel and air to the anode catalyst layer and the cathode catalyst layer, respectively. Can do. As a result, it is possible to efficiently collect current while reducing the obstruction of the supply of liquid fuel and gaseous fuel in the layer thickness direction of the current collector that functions as the extraction electrode.

  The opening portion may be formed as a through-hole in the layer thickness direction of the current collector, and the shape of the opening portion is not particularly limited, but the opening ratio is in the range of 10% to 95%. It is preferable. Here, the aperture ratio of the current collector is calculated as SB / SA × 100 (unit:%), where SA is the electrode area and SB is the total area of the apertures formed in the current collector. Defined by the value The porosity is preferably 40% or more in that methanol can be satisfactorily supplied to the anode catalyst layer and oxygen to the cathode catalyst layer. If the aperture ratio becomes excessively large, the resistance of the current collector may increase or the mechanical strength may be lost. Therefore, the aperture ratio is preferably 90% or less.

The resistance value of the high resistance layer on the electrode is a resistance when a terminal is attached to each of two opposite sides of a square of 1 cm ² and a current is passed in a plane direction, that is, a sheet resistance per 1 cm ^{2 of} area, 10 mΩ to 300 mΩ. It is preferable to be within the range. When the sheet resistance value of the high resistance layer is 10 mΩ or more, the function as a heating element is good, and when it is 300 mΩ or less, for example, when the high resistance layer is used as an extraction electrode together with the low resistance layer, the power generation efficiency is reduced. It can be maintained well. The sheet resistance value of the high resistance layer is more preferably 100 mΩ or more, particularly preferably 150 mΩ or more, and more preferably 200 mΩ or less.

The resistance value of the low resistance layer on the electrode is preferably in the range of 1 mΩ to 30 mΩ as the sheet resistance per 1 cm ² of the area. When the resistance value of the low resistance layer is 1 mΩ or more, it is easy to obtain materials and to produce the low resistance layer. When the resistance value is 30 mΩ or less, the function as the extraction electrode is good. The sheet resistance value of the low resistance layer is more preferably 5 mΩ or more, particularly preferably 10 mΩ or more, and more preferably 25 mΩ or less, particularly preferably 20 mΩ or less.

In the present invention, when, for example, an intermediate resistance layer is provided between the high resistance layer and the low resistance layer, the resistance value of the intermediate resistance layer is intermediate between the resistance value of the high resistance layer and the resistance value of the low resistance layer. However, it is preferable that the resistance value of the middle resistance layer is the sheet resistance per 1 cm ^{2 of} the above-described area, for example, in the range of 50 mΩ to 100 mΩ.

More typically, when the current collector is composed of two layers of a high resistance layer and a low resistance layer, the resistance value of the low resistance layer is about 15 mΩ in terms of the sheet resistance, and the resistance value of the high resistance layer is A combination having a sheet resistance of about 150 mΩ is preferable. For example, in a fuel cell having an electrode area of 5 cm ² , a combination in which the sheet resistance of the low resistance layer is about 15 mΩ and the sheet resistance of the high resistance layer is about 150 mΩ is preferable.

  In the present invention, the current collector is preferably formed so as to cover the entire electrode surface. In this case, the electrode and the electrolyte layer can be heated more uniformly, and there is little possibility that unevenness of the output current and potential distribution occur in the electrode, and the power generation characteristics of the entire fuel cell can be further improved.

<Separator>
In the present invention, the separator has a function of preventing a short circuit between the anode side and the cathode side when a plurality of unit cells of the fuel cell are stacked and forming a fuel flow path. As the material of the separator, a polymer material excellent in acid resistance and methanol resistance, such as polypropylene resin, polycarbonate, acrylic resin, PTFE (polytetrafluoroethylene) resin, polyphenylene ether resin, PEEK (polyether ether ketone) resin, etc. preferable.

  When the separator is made of an insulating material, for example, in a fuel cell having a structure as shown in FIG. 3, the current can be taken out in the plane direction, and the current is passed through the high resistance layer, so that the structure is small and thin. This has the advantage that the MEA can be uniformly heated easily. Further, since the separator is insulative, the thermal resistance to the outside of the fuel cell is increased, and the heat generated by the current collector can be used for heating the electrode and the electrolyte layer. And has the advantage of better power generation efficiency.

  Examples of the insulating material include polypropylene resin, polycarbonate, acrylic resin, PTFE (polytetrafluoroethylene) resin, polyphenylene ether resin, polyimide resin, PEEK (polyether ether ketone) resin, and these polymer resins. Examples include those coated with an exterior and filled with polyurethane foam, glass wool, polystyrene foam, polyethylene foam and the like.

  On the other hand, when the separator is made of a heat-insulating material, the conduction of heat generated by the current collector to the outside of the fuel cell is suppressed, and the heating efficiency of the electrode and the electrolyte layer according to the present invention becomes better, and the fuel cell This has the advantage that the startability and the power generation efficiency are improved. Examples of the material having excellent heat insulating properties include those in which the exterior is coated with the above-described polymer resin, and polyurethane foam, glass wool, polystyrene foam, polyethylene foam and the like are filled inside.

<Anode diffusion layer, cathode diffusion layer>
In the present invention, an anode diffusion layer and a cathode diffusion layer may be provided as the diffusion layer. The diffusion layer may be provided as a conductive member between the electrode and the current collector, or may be provided to face the electrode with the current collector interposed therebetween. The anode diffusion layer functions to supply fuel and discharge carbon dioxide between the current collector and the anode electrode. The cathode diffusion layer functions to supply an oxidant represented by oxygen between the current collector and the cathode electrode and to discharge generated water.

  The diffusion layer can be formed as an electron conductive porous body such as carbon. In addition, when the water-repellent porous body is provided so as to face the electrode across the current collector, the water-repellent porous body repels the low-concentration methanol aqueous solution, and the porous body contains carbon dioxide, air, etc. When a large amount of the gas is contained, the heat insulating property of the porous body is improved and the methanol aqueous solution is not deprived of heat, so that the temperature of the fuel cell can be controlled more efficiently.

<Heater>
When a heater is provided in the present invention, the heater has a function of heating the electrode and the electrolyte layer to improve the startability and power generation efficiency of the fuel cell. The heater is preferably installed inside the separator, and particularly preferably integrated with the separator. As the heater, for example, an electric resistance heater made of nichrome wire or the like can be used. A thermistor heater having PTC characteristics is preferably used as a heater because the temperature control system can be simplified. An NTC thermistor heater may be used as a heater, and heating may be performed while monitoring the temperature.

  The heater is preferably subjected to a corrosion resistance treatment. Also, the heater may be a chemical reaction designed so that the reactant does not directly touch the fuel cell, or heat generated by a separately prepared combustor, for example, hydrogen-oxygen by steam reforming of hydrocarbons. It may be a heater that conveys heat, etc. used in the reforming reaction in a fuel cell using as a fuel. You may conduct heat, such as operation | movement heat | fever of apparatus, and heat_generation | fever of devices, such as a power transistor, from the heat source which generate | occur | produces elsewhere by a heat pipe.

(Embodiment 1)
FIG. 3 is a plan view for explaining an example of the configuration of the current collector in the fuel cell of the present invention. FIG. 3 shows a case where the fuel cell is a single cell. In the present invention, with respect to FIG. 3 and subsequent figures, parts not particularly described below have the same configuration as in FIG.

  In the present invention, two or more layers constituting the current collector are laminated with each other through only an insulating layer in a region where the anode electrode or cathode electrode is formed, and a region where the anode electrode or cathode electrode is not formed It is preferable that at least a part of these are electrically connected. In this case, in the region where the electrode is formed, since the low resistance layer and the layer other than the low resistance layer are insulated, the voltage generated when a current is passed through the layer other than the low resistance layer in the current collector It is possible to prevent the potential distribution due to the drop from being applied to the electrode and to satisfactorily prevent deterioration of the catalyst in the electrode. In addition, since each layer constituting the current collector is laminated at a relatively short distance through only the insulating layer, the heat generated by flowing a current through the layers other than the low resistance layer is comparatively transmitted through the low resistance layer. It is transmitted to the electrode and the electrolyte layer with little loss, and the electrode and the electrolyte layer are efficiently heated. In addition, in the region where the electrode is not formed, there is an electrical joint portion between the low resistance layer and the layer other than the low resistance layer in the current collector. The heat generated by flowing an electric current can be efficiently transmitted to the electrode and the electrolyte layer through the bonding site, and the electrode and the electrolyte layer can be efficiently heated.

  In the fuel cell shown in FIG. 3, the current collector is composed of two layers of a high resistance layer 303a and a low resistance layer 303b, and an insulating layer 311 is formed between the high resistance layer 303a and the low resistance layer 303b. The high resistance layer 303a and the low resistance layer 303b are electrically insulated by an insulating layer 311 in a region where the anode electrode 302a and the cathode electrode 302b are formed. On the other hand, in the region where the anode electrode 302a and the cathode electrode 302b are not formed, on the side opposite to the side where the current collector is drawn outside the separator, that is, the current extraction part side outside the cell, The shape of the high-resistance layer 303a is designed so that the 303a and the low-resistance layer 302b are in direct contact with each other without the insulating layer 311, thereby electrically connecting the high-resistance layer 303a and the low-resistance layer 303b.

  Note that the high resistance layer 303a, the insulating layer 311 and the low resistance layer 303b are joined by the insulating adhesive layer 312 at the intermediate portion on the current extraction portion side, and the high resistance layer 303a and the insulation at the end opposite to the extraction portion side. The layer 311 and the low resistance layer 303b are sealed by the insulating sealing portion 313.

  In the present invention, for example, when an insulating layer is provided as shown in FIG. 3, the insulating layer is preferably made of a porous material. In this case, the discharge efficiency of carbon dioxide and water, which are byproducts of the reaction in the fuel cell, and the diffusion supply of fuel and oxygen become better, and the power generation output is improved.

  As the porous body, a water-repellent porous body such as PTFE (polytetrafluoroethylene), PVDF (polyvinylidene fluoride), PP (polypropylene) is preferable. When a water-repellent porous body is used, the generated water is pushed out on the cathode side, and an oxygen supply port is secured, so that an advantage of suppressing a decrease in output power due to insufficient supply of oxygen can be obtained. On the side, carbon dioxide and water, which are by-products, are quickly discharged to the outside through the porous body, so that it is possible to prevent the fuel supply from being hindered when bubbles are attached to the catalyst layer. There is an advantage that a decrease in output power due to insufficient supply of fuel such as an aqueous solution can be suppressed.

The porous material, silica (SiO _2), such as titanium oxide (TiO _2), the other surface of the inorganic porous material is hydrophilic silica (SiO _2), hydrophilic such as titanium oxide (TiO ₂₎ A porous layer made of a composite layer composed of particles exhibiting an organic polymer and an organic polymer having a hydrophilic functional group such as a hydroxyl group, a sulfonic acid group, a carbonyl group, an amide group, or the like can be used. .

  In FIG. 3, the low resistance layer 303b of the current collector is formed so as to be in contact with the electrodes on both the anode side and the cathode side. Further, a portion of the current collector other than the low resistance layer 303 b, that is, the high resistance layer 303 a is formed so as to be in contact with the electrode through the insulating layer 311. The high resistance layer 303a has an extraction portion for extracting current from the low resistance layer 303b to the outside of the fuel cell through the high resistance layer 303a. As a result, when the current is taken out, the current collected from the electrode flows through the low resistance layer 303b in the plane direction when the current is output as it is through the low resistance layer 303b, and the current reaching the extraction portion is It is taken out of the cell as it is. On the other hand, when a current is output through the high resistance layer 303a, the current flows in a region opposite to the take-out portion of the low resistance layer 303b and passes through the interface between the high resistance layer 303a and the low resistance layer 303b. It is transmitted to the layer 303a, and further flows through the high resistance layer 303a in the plane direction to reach the extraction portion. Here, since the high resistance layer 303a is not in contact with the electrode, the high resistance layer can generate heat more uniformly.

  Both the high resistance layer 303a and the low resistance layer 303b are preferably formed so as to have a uniform resistance value in the plane direction in order to efficiently flow current in the plane direction.

  In this case, since the electrodes and the electrolyte layer can be heated more uniformly, the resistance value of each layer constituting the current collector is in the plane direction, that is, at the interface between the layers, at least in the region where the electrode is formed. It is preferable that the value is uniform in the direction parallel to the.

  As a method of making the resistance value of each layer constituting the current collector uniform in the plane direction, for example, a through hole is provided in the current collector, and the variation in the thickness of the conductor portion (that is, the portion other than the through hole) is an ideal value. Can be exemplified by a method in which the width and the pitch of the through holes are reduced to about ± 10%.

In addition, evaluation of whether or not the resistance value of the current collector is uniform in the planar direction is made by measuring the resistance value by, for example, the DC two-terminal method or the DC four-terminal method, and the variation in sheet resistance per cm ² is ideal. It can be evaluated by a method of determining that the width is ± 10% or less from the value and is uniform (ie, uniform).

When the current collector of the present invention is configured as shown in FIG. 3 and consists of two layers, a high resistance layer 303a and a low resistance layer 303b, the specific resistance of the low resistance layer 303b is 1 × 10 ⁻⁴ Ω. The specific resistance of the high resistance layer 303a is preferably about 3 × 10 ⁻³ to 4 × 10 ⁻³ Ω · cm. For example, in the case of a fuel cell having an electrode area of 5 cm ² , the resistance value of the low resistance layer 303b is preferably 10 mΩ or less in terms of the sheet resistance per 1 cm ² described above, and the resistance of the high resistance layer 303a. The value is preferably about 200 to 400 mΩ in terms of the sheet resistance per 1 cm ² described above.

  In the present invention, each layer constituting the current collector can be joined to another layer by, for example, solder, Ag paste, fusion, a conductive sheet, a conductive adhesive, or the like.

  The material constituting the insulating layer 311 is preferably a polymer resin, such as polytetrafluoroethylene (PTFE) resin, polyvinylidene fluoride (PVDF) resin, polyimide resin, polyethylene resin, polypropylene resin, polyacrylic resin, polyacrylic ester. Resin etc. can be illustrated. In addition, ceramic and the like are also preferable. For metals such as titanium and SUS that form an oxide film passivation on the surface, heat treatment may be performed at a high temperature of 400 to 800 ° C. in an oxygen atmosphere to form a high-resistance oxide film as an insulating layer.

  As a material constituting the insulating adhesive layer 312, for example, an ultraviolet curable type or a thermosetting type, and a resin excellent in sulfuric acid resistance and methanol resistance is preferable. Specifically, acrylic resins, polyimide resins, ester resins, polyacrylate resins, and the like are preferable.

  In addition, as a resin used for the insulating layer and the insulating adhesive layer, a photosensitive resist film or a photosensitive plate-making resin used for a metal mask or the like is also preferably used.

  For the insulating sealing portion 313, a polymer resin similar to that used for the insulating layer 311 can be preferably used. The insulating adhesive layer 312 is provided outside the region where the electrode is formed, and typically bonds the high resistance layer 303a and the low resistance layer 303b. The insulating adhesive layer 312 is preferably arranged so as not to cover the electrode formation region.

  Also in the configuration as shown in FIG. 3, it is preferable that the current collector, the electrode, and the electrolyte layer are integrated and in close contact.

(Embodiment 2)
FIG. 4 is a plan view for explaining an example of the configuration of the current collector in the fuel cell of the present invention. The structure shown in FIG. 4 can be formed on the anode side and / or the cathode side, but only one is shown in FIG. In FIG. 4, the current collector is composed of two layers, a high resistance layer 403a and a low resistance layer 403b. The insulating layer 411a is formed so as to coat the high resistance layer 403a, and the high resistance layer 403a and the electrode 402 are insulated by the insulating layer 411a. The current collector is disposed so as to be embedded in the electrode 402.

  In the first embodiment, an example in which the shape of the high resistance layer is designed so as to have electrical connection with the low resistance layer has been described. However, in this embodiment, the high resistance layer 403a and the low resistance layer 403a are formed by the bonding member 414. The resistance layer 403b is electrically connected.

  In FIG. 4, a current can be extracted from the extraction portion from the low resistance layer 403b through the bonding member 414 and the high resistance layer 403a. In this case, the electrode and the electrolyte layer can be heated more efficiently by passing a current through the high resistance layer by switching the switch.

  In a region where the electrode 402 is not formed, an insulating adhesive layer 412 is provided on the extraction portion side, and an insulating sealing portion 413 for sealing, a bonding member 414, and an end portion on the opposite side to the extraction portion are provided. Is provided. As a result, when the current is extracted, the current collected from the electrode flows in the plane direction of the low resistance layer 403b when the current is output as it is through the low resistance layer 403b, and reaches the extraction portion. Is taken out of the cell as it is. On the other hand, when a current is output through the high resistance layer 403a, the current flows in a region opposite to the extraction portion of the low resistance layer 403b and passes through the interface between the high resistance layer 403a and the low resistance layer 403b. It is transmitted to the high resistance layer 403a, and further flows in the planar direction through the high resistance layer 403a to reach the extraction portion. Here, since the high resistance layer 403a is not in contact with the electrode, the high resistance layer can generate heat more uniformly.

  Both the high resistance layer 403a and the low resistance layer 403b are preferably formed so as to have a uniform resistance value in the plane direction in order to allow current to flow efficiently in the plane direction.

(Embodiment 3)
FIG. 5 is a plan view for explaining an example of the configuration of the current collector in the fuel cell of the present invention. The structure shown in FIG. 5 can be formed on the anode side and / or the cathode side, but only one of them is shown in FIG. In the present invention, for example, as shown in FIG. 5, an electrode 502 is formed in the through-hole portion of the current collector, and the high resistance layer 503 a is covered with the insulating layer 511 and insulated from the electrode 502. Is preferred. The low resistance layer 503b can be formed in contact with the electrolyte layer 101. According to such a configuration, heating of the electrode and the electrolyte layer can be performed more uniformly and efficiently.

  In FIG. 5, the insulating adhesive layer 512, the insulating sealing portion 513, and the bonding member 514 have the same shapes and functions as the insulating adhesive layer 412, the insulating sealing portion 413, and the bonding member 414 in FIG. 4. In FIG. 5, the high-resistance layer 503a and the low-resistance layer 503b of the current collector are formed so as to have through holes penetrating in the layer thickness direction. Thus, the low resistance layer 503b is in contact with the electrode 502.

  In the first to third embodiments, a case where a current collector including a high resistance layer and a low resistance layer is used and an electrical junction is provided in a region where the high resistance layer and the low resistance layer are not formed with electrodes is described. did. Here, for example, as shown in FIG. 3, an example of a method for manufacturing a current collector in the case where the above-described electrical junction is provided by adjusting the shape of the high resistance layer will be described below. In addition, below, the aspect which adjusts resistance value by providing a through-hole in a collector is also demonstrated collectively.

  FIG. 6 is a diagram illustrating an example of a method for manufacturing a current collector having a through hole. For example, a P-type silicon substrate of about 0.01 Ω · cm has a diameter of about 100 μm and a pitch of about 200 μm, and through holes are formed by hexagonal close-packing to form a substrate 15 (FIG. 6A). At this time, when N-type silicon, for example, is used as the substrate, the through holes can be made denser by, for example, a photo-assisted electrolytic etching method. The high resistance layer is formed by the above method.

  Next, metal layers 25 and 35 such as gold (Au), for example, are stacked on a part of the region on the substrate 15 by, for example, sputtering (FIG. 6B). Next, the surface of the substrate is oxidized to insulate portions other than the metal layers 25 and 35 on the upper surface. In the oxidation treatment, for example, the oxide layer 45 having a thickness of about 100 nm can be formed by heating in dry oxygen at 900 ° C. for 3 hours (FIG. 6C).

  As the metal foil 55, for example, a titanium foil having a shape similar to the through hole of the substrate 15 is formed in 100 μm by drilling, or at least a part of the through hole of the substrate 15 is a through hole of the titanium foil. What formed the through-hole of the shape which is contained by the hole process etc. can be used. The titanium foil is preferably further plated with, for example, Au (gold). Specifically, when the substrate 15 and the metal foil 55 are laminated as described above, a thickness of Au is applied to a titanium foil in which holes that can penetrate both of them are formed by punching, lath processing, or the like. It can be used by plating at about 0.2 μm. The low resistance layer is formed by the above method.

  Next, the high-resistance layer substrate 15 and the low-resistance layer metal foil 55 are joined together by soldering. The solder portion can be coated with PVDF, photosensitive polyacrylic resin, photosensitive polyimide resin, or the like. As described above, two current extraction portions 65 and 75 are formed, and a current collector having a through hole is manufactured (FIG. 6D). It can be used as a current collector composed of a resistance layer and a low resistance layer.

(Embodiment 4)
FIG. 7 is a plan view for explaining an example of the configuration of the current collector in the fuel cell of the present invention. In the present invention, it is sufficient that the current collector includes at least a high resistance layer and a low resistance layer, but between the high resistance layer and the low resistance layer, for example, between the high resistance layer and the low resistance layer. A current collector composed of three or more layers having a layer having a resistance value can also be used. FIG. 7 illustrates an example in which a current collector including three layers of a high resistance layer 703a, a low resistance layer 703b, and an intermediate resistance layer 703c having an intermediate resistance value between the high resistance layer 703a and the low resistance layer 703b is used. Shows about. In FIG. 7, insulating layers 711a and 711b for insulating the high resistance layer 703a, the low resistance layer 703b, and the middle resistance layer 703c are provided.

  The high resistance layer 703a, the low resistance layer 703b, and the middle resistance layer 703c are electrically insulated through the insulating layers 711a and 711b in the region where the anode electrode and the cathode electrode are formed. On the other hand, in the region where the anode electrode and the cathode electrode are not formed, the high resistance layer 703a, the low resistance layer 703b, and the middle resistance layer 703c are in direct contact with each other without an insulating layer on the side opposite to the current extraction portion side. Connected. The insulating adhesive layer 712 and the insulating sealing portion 713 can be formed in the same manner as the insulating adhesive layer 312 and the insulating sealing portion 313 shown in FIG. Thereby, the electrode and the electrolyte layer can be heated more efficiently by passing a current through the high resistance layer or the middle resistance layer by switching the switch.

  In FIG. 7, the low resistance layer 703b of the current collector is formed so as to be in contact with the electrodes on both the anode side and the cathode side. Further, portions other than the low resistance layer 703 b in the current collector, that is, the high resistance layer 703 a and the middle resistance layer 703 c are formed so as to be in contact with the electrode through the insulating layer 711. As a result, when the current is extracted from the extraction portion of the low resistance layer 703b, the current collected from the electrode flows through the low resistance layer 703b in a plane direction, that is, a direction perpendicular to the layer thickness direction. Reach the extraction part. The current that has reached the extraction section is extracted out of the cell as it is. On the other hand, when the current is extracted from the extraction portion of the medium resistance layer 703c, the current that has flowed to the side opposite to the extraction portion of the low resistance layer 703b is caused to flow through the interface between the intermediate resistance layer 703c and the low resistance layer 703b and the high resistance layer 703a. Then, it is transmitted to the middle resistance layer 703c, flows through the middle resistance layer 703c in the plane direction, and reaches the extraction portion. Similarly, when the current is extracted from the extraction portion of the high resistance layer 703a, the current flowing on the opposite side to the extraction portion of the low resistance layer 703b passes through the interface between the high resistance layer 703a and the low resistance layer 703b. And flows through the high resistance layer 703a in the plane direction to reach the extraction portion.

  As described above, even when the current collector is composed of three or more layers having different resistance values, the heat generation amount of the current collector can be controlled by selecting which of the extraction portions of each layer the current is extracted from. Here, since the high resistance layer 703a and the middle resistance layer 703c are not in contact with the electrode, more uniform heat generation of the high resistance layer and the middle resistance layer is possible.

(Embodiment 5)
FIG. 8 is a plan view for explaining an example of the configuration of the current collector in the fuel cell of the present invention, and FIG. 9 is a cross-sectional view showing the IX-IX cross section of FIG. The configurations shown in FIGS. 8 and 9 can be formed on the anode side and / or the cathode side, but only one of them is shown in FIGS. 8 and 9. In this embodiment, the case where an electrode, a current collector, and an electrolyte layer are stacked in this order will be described. 8 and 9, the high resistance layer 803a of the current collector is covered with an insulating layer 811. Thereby, contact with the electrode and electrolyte layer of a high resistance layer can be prevented more reliably, and heating of an electrode and an electrolyte layer can be performed more uniformly.

  The insulating layer 811 has a portion bonded to the electrolyte layer 101 through the electrode 802 and a portion bonded to the electrolyte layer 101 by the adhesive layer 816. The insulating layer 811, the high resistance layer 803a, and the low resistance layer 803b are formed so as to be sandwiched between the electrodes 802, and an insulating sealing portion 813 and a bonding member 814 are formed.

  The electrode 802 having a shape as shown in FIGS. 8 and 9 is formed by applying a catalyst paste made of carbon particles supporting a catalyst and an electrolyte polymer on the electrolyte layer 101 and drying it, and then laminating a current collector. The catalyst paste can be applied and dried from above. The catalyst paste can be prepared by the following procedure. A catalyst paste for forming an anode electrode (hereinafter also referred to as anode catalyst paste) is a catalyst-supported carbon composed of Pt-Ru particles having a Pt loading amount of 32.5 wt% and a Ru loading amount of 16.9 wt% and carbon particles. Particles (for example, TEC66E50, manufactured by Tanaka Kikinzoku Co., Ltd.), 20 wt% of an alcohol solution of Nafion (registered trademark) (manufactured by Aldrich), isopropanol, and alumina balls at a predetermined ratio of polytetrafluoroethylene (PTFE) ), And mixing for 50 minutes at 500 rpm using a stirring defoamer. Further, by using catalyst-supported carbon particles (for example, TEC10E50E, manufactured by Tanaka Kikinzoku Co., Ltd.) composed of Pt particles having a Pt support amount of 46.8 wt% and carbon particles, a cathode electrode is formed similarly to the anode catalyst paste. A catalyst paste (hereinafter also referred to as a cathode catalyst paste) can be produced. After the current collector and the electrolyte layer 101 are joined, the anode catalyst paste and the cathode catalyst paste are applied and dried, whereby the electrode 802 can be manufactured.

  In the configuration shown in FIGS. 8 and 9, the current collector and the electrolyte layer are integrated by bonding the insulating layer 811 and the electrolyte layer 101 with an adhesive layer 816. This eliminates the need to press the current collector, electrode, and electrolyte layer with fastening members such as bolts and nuts, thereby further reducing the size, thickness, and weight of the cell. The term “integrated” in the present invention means a state of being in close contact without being fastened by, for example, an end plate, bolts, nuts, or the like.

  In addition, since the current collector and the electrolyte layer are integrated using an adhesive layer, there is little risk of peeling off, and a stable contact between the electrode and the electrolyte layer and the current collector can be secured. Property can be further improved.

  As a material for the adhesive layer 816, for example, epoxy resin, phenol resin, unsaturated polyester resin, or the like, polyacrylic acid ester that is a photosensitive resin, polyacrylic resin, or the like can be used.

(Embodiment 6)
In the present invention, when a layer other than the low resistance layer of the current collector is covered with an insulating layer, the insulating layer is preferably made of an electrolyte material. The electrolyte layer is made of an insulating electrolyte. Therefore, in the above case, the layers other than the low resistance layer in the current collector are covered with the electronic insulating electrolyte, and even when a current locally flows through the layers other than the low resistance layer, the electrolyte layer and the catalyst The problem of deterioration can be avoided. Further, since the insulating layer is proton conductive, ion diffusion resistance can be reduced. Furthermore, since the electrolyte layer and the current collector can be firmly bonded, the possibility of causing an increase in ohmic resistance due to the peeling of the current collector is reduced.

  FIG. 10 is a plan view for explaining an example of the configuration of the current collector in the fuel cell of the present invention, and FIG. 11 is a cross-sectional view showing a XI-XI cross section of FIG. The configurations shown in FIGS. 10 and 11 can be formed on the anode side and / or the cathode side, but only one of them is shown in FIGS. 10 and 11. 10 and 11, the current collector is formed between the electrolyte layer 101 and the electrode 1002. The insulating layer 1011 is made of an electrolyte material. The high-resistance layer 1003 a of the current collector is covered with an insulating layer 1011, and a low-resistance layer 1003 b is formed on the insulating layer 1011. The insulating layer 1011 is bonded to the electrolyte layer 101 through the adhesive layer 1016. That is, the high resistance layer 1003a is integrated so as to be embedded in the electrolyte, and the insulating sealing portion 1013 and the bonding member 1014 are further formed. Note that as the material of the adhesive layer 1016, a material similar to that of the adhesive layer 816 can be used.

  10 and 11, the insulating layer 1011 can be made of the same material as the electrolyte layer 101. The insulating layer 1011 and the electrolyte layer 101 are bonded with, for example, a relatively low molecular weight electrolyte polymer having the same configuration as the electrolyte layer 101, and more preferably a lower molecular weight electrolyte polymer than the electrolyte layer 101. It is preferable. Specifically, an electrolyte polymer having a molecular weight lower than that of the electrolyte layer 101 is applied to the electrolyte layer 101 and / or the insulating layer 1011, and the electrolyte layer 101 and the insulating layer 1011 are bonded together, and then bonded by hot pressing. can do. In this case, peeling between the current collector and the electrolyte layer 101 is prevented, and a stable contact between the electrode and the current collector can be secured, so that the reliability of the fuel cell is improved. In addition, since the protons generated at the anode electrode are transferred to the cathode more efficiently, the power generation efficiency of the fuel cell is further improved.

  The electrode 1002 having a shape as shown in FIGS. 10 and 11 is formed by, for example, applying a catalyst paste made of carbon particles supporting a catalyst and an electrolyte polymer on the electrolyte layer 101 and drying it, and then laminating a current collector. Further, the catalyst paste can be applied and dried from above. The catalyst paste can be prepared by the following procedure. A catalyst paste for forming an anode electrode (hereinafter also referred to as anode catalyst paste) is a catalyst-supported carbon composed of Pt-Ru particles having a Pt loading amount of 32.5 wt% and a Ru loading amount of 16.9 wt% and carbon particles. Particles (for example, TEC66E50, manufactured by Tanaka Kikinzoku Co., Ltd.), an alcohol solution of 20 wt% Nafion (registered trademark) (manufactured by Aldrich), isopropanol, and alumina balls in a predetermined ratio of polytetrafluoroethylene (PTFE) It can produce by mixing for 50 minutes at 500 rpm using a stirrer. Further, by using catalyst-supported carbon particles (for example, TEC10E50E, manufactured by Tanaka Kikinzoku Co., Ltd.) composed of Pt particles having a Pt support amount of 46.8 wt% and carbon particles, a cathode electrode is formed similarly to the anode catalyst paste. A catalyst paste (hereinafter also referred to as a cathode catalyst paste) can be produced. After the current collector and the electrolyte layer 101 are joined, the anode catalyst paste and the cathode catalyst paste are applied and dried, whereby the electrode 1002 can be manufactured.

<Fuel cell manufacturing method>
The fuel cell of the present invention is not particularly limited as long as it has the structure as described above, but the fuel cell of the present invention can be produced, for example, as follows. In addition, the well-known method normally used in manufacture of a fuel cell can be used suitably about the part which is not demonstrated below in the manufacturing method of a fuel cell. In the following, the case where the current collector is composed of two layers of a high resistance layer and a low resistance layer and the high resistance layer is covered with an insulating layer will be described first.

  The fuel cell of the present invention typically includes (1) a step of forming a current collector (current collector forming step) comprising a high resistance layer and a low resistance layer, and (2) a high resistance layer and a low resistance. A step of covering the high-resistance layer with an insulating layer (insulation coating step), (3) a step of bonding the high-resistance layer and the low-resistance layer (bonding step), and (4) ) A step of forming a diffusion layer (a diffusion layer formation step), (5) a step of forming an electrode (electrode formation step), and (6) a step of integrally forming the diffusion layer, the current collector, the electrolyte layer, and the electrode. It can manufacture by the manufacturing method which consists of (integration process). When a CCM (Catalyst Coated Membrane) in which an electrode and an electrolyte layer are integrally formed is purchased and used, the electrode forming step (5) can be omitted.

  Here, “integrated” refers to a state in which each member of the MEA is not separated even if pressure is not applied from the outside, specifically, a state in which the members are joined by a chemical bond, an anchor effect, an adhesive force, or the like. Point to. As a method for integrating, for example, a method of fusing the electrolyte layer to the electrode and the current collector by a hot press method can be mentioned. Typically, the solid polymer electrolyte in the electrode and the polymer material constituting the conductive porous substance are deformed by the heat during hot pressing, thereby ensuring bonding by a three-dimensional anchor effect. According to such a method, it is possible to maintain good electrical and heat conductive contact between the current collector and the electrode without tightening with a bolt or nut or the like and applying external pressure.

(1) Current collector forming step The current collector can be produced by, for example, a silicon process. The resistance value of each layer can be controlled by the amount of metal on silicon or the amount of different ions doped into silicon. The use of MEMS (micro electro mechanical systems) technology is preferable in that high-precision microfabrication is possible, and the process is suitable for mass production.

  For example, a current collector can be manufactured by preparing a silicon substrate with holes formed by a drill, a UV-YAG laser, wet etching, or the like and adjusting the silicon substrate to a predetermined size by dicing. In the case of N-type silicon, the holes can be made denser by the photo-assisted electrolytic etching method. Further, a current collector having different resistance values can be formed by partially laminating metal by sputtering. Specifically, the surface of the silicon substrate is oxidized to insulate portions other than the metal. Next, a metal is laminated on the surface of the substrate oxidized as described above. Or it adheres through metal foil and a metal plate adhesive agent. Instead of oxidation treatment, an insulating sheet such as polyimide may be applied or adhered to form. If necessary, the metal surface is plated with gold. A switch is formed in each of the two electrode outlets.

  In the current collector forming step, for example, a plurality of metal plates or metal foils to be used as a current collector are formed on a plane by a punching method, an etching method, a laser method, a drilling method using a drill, or the like. Openings can be formed.

  In the punching method, an opening can be formed by preparing a mold for forming a predetermined opening pattern and pressing and punching it to a current collector. In such a manufacturing method, a plurality of holes can be formed at one time without using a special apparatus, and inexpensive processing is possible. Further, since the machining is not applied with heat, it is possible to form a hole that is independent of the selected current collector material and material.

  As an etching method, a photoetching process method used in printed wiring technology or the like can be used. A photosensitive resist is applied or laminated on one surface of the current collector to form a photosensitive layer, and after forming a resist pattern of the current collector to be left after exposure, development and etching are performed to open holes. Can be formed. In such a manufacturing method, it is possible to form a plurality of openings at a time and to process a fine opening pattern.

  In the laser method, an opening can be formed using a laser such as excimer, carbon dioxide gas, or xenon. At this time, by using a condensing laser, the current collector can be moved on the XY stage for each single opening to form a predetermined opening pattern.

  In any of the above methods, the resistance value of the current collector can be controlled by the thickness, hole diameter, and hole area ratio of the metal plate or metal foil.

  Further, a mesh in which metal wires are knitted into a plain weave can be used as the current collector. In this case, the resistance value can be controlled by controlling the wire diameter and mesh size of the mesh.

  In addition, when the current collector needs acid resistance and chemical resistance, after forming an opening by the above method, a metal having excellent acid resistance and chemical resistance such as Au and Pt is collected. Plating on the surface is preferred.

(2) Insulation coating step The high resistance layer coated with the insulation layer is, for example, sandwiching the current collector with a polyimide sheet formed so as to cover the entire surface of the electrode, and sealing the outer periphery with a polyimide adhesive. It can be produced by a method. Moreover, a negative photosensitive polyimide resin is apply | coated to parts other than the electric current extraction part in a high resistance layer, and a high resistance layer can be coat | covered with an insulating layer by hardening this polyimide resin by UV irradiation. Alternatively, a thermosetting polyimide resin may be used and cured by curing at a curing temperature. It is preferable that the polyimide sheet used as an insulating layer is a porous body. However, in this case, the above-mentioned catalyst paste enters the inside of the pores of the porous body, and the pore diameter is so small that the high resistance layer of the current collector and the electrode are not in electrical contact with each other. Use the body. The pore diameter is preferably, for example, 1 μm or less in diameter in that electrical contact between the high resistance layer of the current collector and the electrode can be satisfactorily prevented.

  Examples of other porous sheets that can be used as the insulating layer include polypropylene and polyethylene nonwoven fabrics and expanded PTFE. When a water-repellent porous material is used as the insulating layer, it is preferable to extend the porous material to the outside of the cell housing so that carbon dioxide can be discharged. Alternatively, the insulating layer may be formed by a method of applying PVDF (polyvinylidene fluoride) dissolved in an NMP (N-methylpyrrolidone) solvent to a current collector. In this case, it is preferable not to block the opening formed in the opening forming step.

(3) Joining process As a method of joining the high resistance layer and the low resistance layer of the current collector, the high resistance layer and the low resistance layer are joined by a joining member such as solder outside the region where the electrodes are formed. Or the like can be used. In this case, it is preferable to use low-temperature solder as the joining member. Soldering may be performed before the step (2). Further, the high resistance layer and the low resistance layer may be joined by caulking, bolts, or nuts. At that time, for example, a silver paste is preferably applied so that the contact area of the joint portion is increased. Further, bonding may be performed by adhering the high resistance layer and the low resistance layer with a paste in which conductive particles such as carbon particles and an organic polymer are dispersed in a solvent. It is preferable to provide an insulating sealing portion at the joint portion by coating with a resin having excellent heat resistance and insulation properties such as polyimide and PDVF. The insulating sealing portion is more preferably made of a thermosetting resin or a photosensitive resin.

(4) Diffusion layer forming step Of the current collector produced in the step (3) above, an adhesive liquid is applied to the surface opposite to the surface to be bonded to the electrode, and the current collector and The current collector and the diffusion layer can be integrated by bonding the diffusion layer and further thermocompression bonding in an integration step (6) described later. As the diffusion layer, typically a porous body is preferably used. Further, the adhesive liquid is preferably a polymer having the same physical properties as the porous body forming the diffusion layer. When the hydrophilic liquid is provided, the hydrophilic polymer is replaced with the water-repellent porous body. When it is provided, it is preferable to use a water-repellent polymer.

(5) Electrode forming step A catalyst paste obtained by dispersing catalyst particles, conductive particles, and an electrolyte in an organic solvent is uniformly applied using a bar coating method, a screen printing method, a spray coating method, or the like. The electrode can be formed by a method of removing the organic solvent in the paste. In such a method, since an electrode having a large number of pores can be formed, the effective surface area of the catalyst particles can be increased.

  In the present invention, the catalyst layer constituting the electrode may be formed on the surface of the electrolyte layer. For example, the catalyst layer may be formed on the surface of a diffusion layer made of a conductive porous material covered with a conductive layer. By forming the catalyst layer integrally with the electrolyte layer or the conductive layer in advance, it is possible to obtain an interface with good adhesion. When the conductive layer is exposed by the mask, the catalyst layer and the conductive layer can be brought into direct contact by applying and forming the catalyst layer from above.

  Furthermore, for example, a method of forming a catalyst layer on a plastic film or the like (not shown) and then transferring the catalyst layer to an electrolyte layer or a current collector may be used. In such a production method, the catalyst layer can be separately formed in advance. Therefore, even for an organic solvent that lowers the proton conductivity of the electrolyte layer or an organic solvent that forms an insulating layer on the surface of the conductive layer, the dispersibility between the catalyst particles and the conductive particles is improved. It can be used as a solvent for the paste.

(6) Integration step The current collector, the electrolyte layer, and the electrode can be integrated by, for example, thermocompression bonding. Specifically, the catalyst layer surface of the electrolyte layer on which the catalyst layer is formed, obtained in the electrode forming step (5), and the assembly produced in the steps (1), (2), and (3) above. It arrange | positions so that the opening part of an electric conductor may contact, and also arrange | position the diffusion layer provided at the process of said (4). Next, using a hot press machine, thermocompression bonding is performed at a temperature exceeding the softening temperature and glass transition temperature of the electrolyte layer, the catalyst layer, the diffusion layer, and the adhesive liquid used in the step (4).

  The MEA produced by the above method has good adhesion at each interface and a fine aperture pattern is formed. By producing a fuel cell using such an MEA, It is possible to suppress a decrease in output voltage due to insufficient supply of methanol and oxygen.

  In the present invention, when the current collector is composed of three layers having different resistance values, for example, the MEA can be manufactured by the following method. That is, a current collector composed of three layers is prepared so as to have different resistance values in all three types in the above step (1). Moreover, in said process (2), the solution of PVDF is apply | coated to layers other than a low resistance layer among electrical power collectors, and electronic insulation is provided. In the step (3), a three-layer current collector is bonded. As shown in FIG. 7, a low resistance layer 703b is bonded to an electrode, and an intermediate resistance layer 703c, an insulating layer 711a, and a high resistance layer 703a are stacked in this order with the insulating layer 711b interposed therebetween. By providing a switch in each layer of the current collector, it is possible to control the output current to flow in each layer.

  In the present invention, when the current collector, the insulating layer, and the electrolyte layer are joined, the above steps (1) to (5) are as described above, and in the integration step of step (6), the insulating layer is formed. There is a method of adhering to the electrolyte layer. Outside the electrode formation region, the electrolyte layer and the insulating layer can be bonded using an adhesive. As the adhesive, the same polymer as the electrolyte layer is applied to the insulating layer and the electrolyte layer, and the insulating layer and the electrolyte layer are overlapped by the method described in the above step (6) and bonded by hot pressing. In addition, a polymer that is excellent in acid resistance and chemical resistance, softens at the temperature during hot pressing, and can be bonded by thermocompression bonding is preferably used as the adhesive. In addition, a polymer that is thermoset at a temperature lower than the heat resistant temperature of the electrolyte layer, that is, a temperature at which the electrolyte layer does not change or soften is preferable. As a result, the current collector and the MEA can be firmly adhered to each other, and long-term improvement in adhesion, reduction of loss due to contact resistance during current collection, and improvement of heat conduction efficiency can be realized over a long period of time. I can do it. This improves the reliability and yield of the product.

  In the present invention, when an insulating layer made of an electrolyte material is provided, in step (2), an electrolyte material is used as the material of the insulating layer, and as an adhesive in the integration step of step (6), for example, the electrolyte material is an organic solvent. A dispersed solution can be used. Thereby, not only the current collector and the electrolyte layer are firmly bonded, but also protons obtained in the anode catalyst layer of the anode electrode can quickly move to the electrolyte layer and move to the cathode side. Also, on the cathode side, diffusion of protons and water from the electrolyte layer to the cathode catalyst layer is improved, and the output power of the fuel cell can be improved.

  FIG. 12 is a cross-sectional view showing the structure of the fuel cell of the present invention. In the fuel cell 1200, an anode electrode 1202a and a cathode electrode 1202b are formed inside the housing 59 so as to face each other with the electrolyte layer 1201 interposed therebetween. A low-resistance layer 1203b is formed as the anode current collector, and a high-resistance layer 1203a and a low-resistance layer 1203b are formed as the cathode current collector with the insulating layer 1211 sandwiched therebetween. Further, the anode-side diffusion layer 1208a and the cathode side are formed. The diffusion layer 1208b is formed. The high resistance layer 1203a and the low resistance layer 1203b are electrically connected by a bonding member 1214 in a region where no electrode is formed. A cathode electrode is formed by pressing and pressing a cathode current collector against a cathode-side diffusion layer 1208b made of carbon GDL, and applying a cathode catalyst layer as a cathode electrode 1202b on the cathode current collector. On the anode side, a fuel container 19, a fuel supply port 29, and a ventilation hole 49 are provided. An anode electrode wiring 69a and a cathode electrode wiring 69b are connected to the anode current collector and the cathode current collector, respectively.

As the low resistance layer 1203b, a metal plate (expanded metal) having a diamond-shaped through-hole with a thickness of about 0.5 mm and a width of about 1 mm on a Ti plate having a thickness of about 100 μm and gold plated to a thickness of 1 μm is used. be able to. Further, as the high resistance layer 1203a, for example, a SUS316L mesh that is a wire mesh (100 mesh) made of SUS316L and having a wire diameter of 30 μm can be used. For example, the anode diffusion layer 1208a and the anode current collector are fixed by pressing, and an anode catalyst layer is applied as the anode electrode 1202a, so that the anode electrode is formed in contact with the current collector. The anode electrode, for example, the electrolyte layer 1201 made of Nafion (registered trademark) 117, and the cathode electrode are stacked in this order so that the positions of the catalyst forming regions of the anode electrode and the cathode electrode are aligned, for example, at 130 ° C. and 10 kgf / cm ² . A membrane electrode assembly is formed by hot pressing for 2 minutes.

  Furthermore, the housing 59 can be manufactured by cutting out acrylic resin, for example. By adhering the outer periphery of the casing and the membrane electrode assembly using an adhesive layer 39 such as a thermosetting polymer, an epoxy resin, more preferably a photopolymerizable polymer, FIG. The fuel cell shown in FIG.

  The fuel cell of the present invention produced as described above can be suitably applied to, for example, a portable electronic device.

<Fuel cell system>
The present invention is also a fuel cell system for driving an external device as a load, for controlling each of the above-described fuel cells and whether or not current is supplied to two or more layers constituting the current collector. Switch unit, a temperature sensor for detecting the temperature of the anode and / or cathode electrode of the fuel cell and the outside air temperature, and a control unit for controlling the switch unit based on the detection result of the temperature sensor And a fuel cell system. 13-15 is a figure explaining the example of the fuel cell system of this invention. 13 to 15, an example in which the current collector on the anode side and the cathode side is composed of a high resistance layer and a low resistance layer will be described. However, as described above, the current collector is composed of three or more layers. May be. 13 to 15, for convenience, the upper part of the cell structure is described as the cathode side and the lower part is described as the anode side.

(Embodiment 7)
A fuel cell system 1300 illustrated in FIG. 13 includes the fuel cell 300 having the cell structure illustrated in FIG. 3, a temperature sensor 91 provided in the vicinity of the anode electrode, and a control unit 92. 442, 443, 444, 445, 446 are provided. The current collector includes an anode-side and cathode-side high-resistance layer 303a and an anode-side and cathode-side low-resistance layer 303b. The presence or absence of energization to each layer of the current collector can be controlled by each switch. In FIG. 13, the structure of the fuel cell 300 is shown in a simplified manner. Although FIG. 13 shows the case where the temperature sensor 91 is provided in the vicinity of the anode electrode, the installation location of the temperature sensor 91 is not limited to this. Only one temperature sensor or two or more temperature sensors can be provided. Typically, it can be provided in a manner capable of sensing at least one of the temperature of the anode electrode and / or the cathode electrode and the outside air temperature. The temperature of the electrode is preferably sensed directly, but a temperature sensor may be provided near the electrode, and the temperature near the electrode may be sensed as the electrode temperature. It is particularly preferable to provide a temperature sensor in the vicinity of the anode electrode.

  By controlling the temperature by monitoring the temperature with the temperature sensor and switching the part that conducts to the external device between the low resistance layer and high resistance layer of the current collector, it is highly efficient even when the external device is steady The fuel cell can continue to generate electricity. In addition, in a fuel cell using hydrogen and oxygen as fuel, if the water generated at the cathode is not successfully removed, the output may drop if the output is continuously taken out. This is one of the causes that water accumulates and oxygen is not supplied. When the temperature in the vicinity of the electrode is high at a constant time, the water generated at the cathode does not condense and the supply of the cathode fuel and oxygen is not hindered, so that the continuous output characteristics can be improved. According to the present invention, unlike the prior art, the temperature in the vicinity of the catalyst of the electrode can be increased, so that a remarkable output improvement effect can be obtained. Furthermore, according to the present invention, the catalytic activity is also improved. When an organic compound fuel, such as methanol, is used as the fuel, the catalytic activity is deactivated due to CO poisoning, etc., but the deactivation rate can be reduced by operating at a high temperature, improving the continuous output characteristics. Can be made.

  When the fuel cell system of the present invention includes a temperature sensor and a control unit, the fuel cell can be caused to generate power when the temperature of the external device is lower than a predetermined temperature at the time of light load during standby or when the external device is stopped. Durability of the constituent materials of the fuel cell by controlling the temperature of the fuel cell, particularly in the vicinity of the electrode and electrolyte layer, to be less than a certain level by self-heating and, if necessary, heat generated by passing a current through the high resistance layer The effect of not lowering the property is obtained. Further, when the temperature of the electrode and the electrolyte layer is maintained at a predetermined temperature or higher, there is an advantage that the output can be instantaneously taken out from the fuel cell even when the external device suddenly returns from the standby state.

(Embodiment 8)
FIG. 14 shows an example of a fuel cell system including a fuel cell in which a plurality of cell structures similar to the cell structure in the fuel cell shown in FIG. 3 are stacked. Is not shown. The fuel cell system of the present invention preferably further includes a power storage device, and FIG. 14 shows a case where the power storage device is provided.

  A fuel cell system 1400 includes a fuel cell in which a plurality of cells having the same structure, which are represented as cells 300a, 300b, and 300c, are stacked, and a temperature sensor (see FIG. And a control unit 96. 14 is connected to an operation state monitor 93, an operation state monitor 93 that detects opening and closing of switches 441a and 442a, which will be described later, a power storage device 94 including two storage batteries, and a charge / discharge circuit 95. ing. Although the temperature sensor is not shown in FIG. 14, each cell can be provided in the same manner as in FIG. Also in FIG. 14, the structure of the fuel cell is shown in a simplified manner as in FIG. In FIG. 14, a stack structure and a switch connected to an intermediate portion of the stack structure are partially omitted.

  As an example, the connection relationship of three cells 300a, 300b, and 300c in the fuel cell system 1400 will be described. In the cell 300a, the current collector on the anode side and the current collector on the cathode side are composed of a high resistance layer 303a and a low resistance layer 303b. The same applies to the other cells 300b and 300c. Whether the current collector is energized or not can be controlled by the switch unit.

  The cathode side of the cell 300 a is connected to a terminal (+ side) of an external device via a switch and an operation state monitor 93. Specifically, the switch 441a is provided as a first switch element between the operation state monitor 93 and one end side of the high resistance layer 303a on the cathode side. The switch 442a is provided as a second switch element between the operation state monitor 93 and the low resistance layer 303b on the cathode side.

  In addition, a switch for connecting the cell 300a and the cell 300b is provided. Specifically, a switch for connecting the anode side of the cell 300a and the cathode side of the cell 300b is provided. In this example, as an example, the switch 444a for connecting the low resistance layer 303b on the anode side of the cell 300a and the low resistance layer 303b on the cathode side of the cell 300b, the high resistance layer 303a on the anode side of the cell 300a and the cell 300b The case where the switch 445a for connecting with the cathode side high resistance layer 303a is provided is shown. Similar switches 444b and 445b are provided when connecting other cells connected in series.

  In addition, a switch is provided corresponding to each cell, connected to power storage device 94 and charge / discharge circuit 95, and provided to supply a current to the high resistance layer of each cell. Specifically, a switch 447a for connecting between one end side of the high resistance layer 303a on the cathode side of the cell 300a and the charge / discharge circuit 95, and the other end side of the high resistance layer 303a on the cathode side of the cell 300a, A switch 443a for connecting the power storage device 94 is provided. Similarly, a switch 448a for connecting between one end side of the high resistance layer 303a on the anode side of the cell 300a and the charge / discharge circuit 95, the other end side of the high resistance layer 303a on the anode side of the cell 300a, and the power storage device And a switch 446 a for connecting to the terminal 94. The same applies to other cells, and a case is shown in which switches 447b and 443b are provided on one end and the other end side corresponding to the high resistance layer 303a on the cathode side of the cell 300b, respectively. Further, the case where switches 448b and 446b are provided on one end and the other end side corresponding to the high resistance layer 303a on the anode side of the cell 300b is shown.

  Further, a case is shown in which switches 447c and 443c are provided on one end and the other end side corresponding to the high resistance layer 303a on the cathode side of the cell 300c, respectively. The case where switches 448c and 446c are provided on one end and the other end side corresponding to the high resistance layer 303a on the anode side of the cell 300c is shown. In addition, a case where a switch 449c for connecting between one end side of the high resistance layer 303a on the anode side of the cell 300c and the power storage device 94 is provided is shown.

  The anode side of the cell 300c is connected to a terminal (− side) of an external device via a switch. Specifically, one of the switches 444c as the fourth switch element is connected to the terminal (− side) of the external device, and the other is connected to the low resistance layer on the anode side. Also, one of the switches 445c as the third switch element is connected to the terminal (− side) of the external device, and the other is connected to the high resistance layer on the anode side.

(Embodiment 9)
The fuel cell system of the present invention may include a monitor unit for detecting the output current and / or the output voltage of the fuel cell instead of or in addition to the above temperature sensor. A fuel cell system 1500 shown in FIG. 15 shows an example in which a monitor unit 97 is provided instead of or together with the temperature sensor of the fuel cell system 1400 shown in FIG. 14, and a control unit 98 is provided as a control unit. .

  When the fuel cell is a direct methanol system in particular, factors that cause a decrease in output include insufficient supply of fuel due to condensation of water generated at the cathode and poisoning of the catalyst by carbon monoxide in the catalytic reaction process. When the fuel cell system of the present invention has an output current and / or output voltage monitor, the output current and / or output voltage of the fuel cell is monitored, and the output current and / or output voltage has decreased. In addition, the fuel cell can be controlled so that the current is heated by the current collector within a range where the temperature does not become too high as the heat resistance of the material of the fuel cell. As a result, the catalytic activity can be improved and the poisoning can be recovered, and the condensed water can be evaporated to improve the fuel supply to the cathode. In the fuel cell according to the present invention, the current collector is provided in the vicinity of the electrode and the electrolyte layer, so that the time and energy required for the temperature of the catalyst to increase can be reduced compared with the conventional case, and The energy of the supplied fuel can be used for generated power with higher efficiency.

  As a temperature sensor provided in the fuel cell system of the present invention, for example, a thermocouple or the like can be used. As the switch, for example, a switch using a semiconductor such as a MOS transistor or a thyristor, a mechanical relay using an electromagnetic coil, or the like can be used.

  When the control unit provided in the fuel cell system of the present invention is a temperature control unit on the assumption that it is combined with a temperature sensor, it is preferable to use a thermistor as the temperature sensor. Specifically, for example, a thermistor is provided at a position where the temperature is to be sensed, for example, in the vicinity of the anode electrode, and a circuit is assembled so that a switch such as a transistor is turned on / off by a resistance change of the thermistor. This makes it possible to perform automatic temperature control by switching circuits. This eliminates the need for complicated control and power consumption by the circuit, and enables the fuel cell to be miniaturized. Examples of the transistor include a bipolar transistor and an FET transistor. As the transistor, an FET transistor driven by voltage is preferable in terms of power consumption and low power consumption. Further, it is preferable to control the temperature by inputting the resistance value of the thermistor to the comparator and comparing the resistance value at an arbitrary temperature with the comparator. Further, it may be controlled by calculating a value AD-converted using a microcomputer by a CPU. For example, “NTC thermistor NT” manufactured by KOA Corporation can be preferably used as the thermistor. A platinum thin film temperature sensor manufactured by KOA Corporation can also be used as the temperature sensor. When a temperature sensor is installed in the vicinity of an electrode, temperature measurement is performed by bringing a temperature sensor whose surface is covered with an insulating film into contact with the electrode, and the temperature at that time can be regarded as the temperature of the electrode.

  For example, a microcomputer is preferably used as the control unit of the fuel cell system of the present invention, and an AD converter is particularly preferable. Further, the value of the output current can be monitored by, for example, performing current-voltage conversion using a resistor and an operational amplifier, inputting the voltage value to the AD converter terminal of the microcomputer, and calculating by the CPU of the microcomputer. The value of the output voltage can be monitored by connecting a node to be measured with a resistor and the ground. When the output voltage is high, it is preferable to use a plurality of resistors as the above-described resistors, and it is preferable to input a divided voltage value of the resistors to the AD converter terminal and to calculate it by the CPU of the microcomputer.

  The fuel cell system of the present invention preferably includes a fuel cell and a power storage device as shown in FIGS. 14 and 15 for example. In this case, the current extracted from the fuel cell can be stored in a power storage device including one or two or more storage batteries, such as a secondary battery and a capacitor, and can be reused. As a result, when the output of the fuel cell is reduced or when the fuel cell is started, the output power that is insufficient by supplying current from the power storage device can be compensated, and the temperature in the vicinity of the electrode and the electrolyte layer can be maintained at a certain level or more. On the other hand, when the power storage device is in a fully charged state, power generation from the fuel cell can be stopped and power can be supplied from the power storage device to an external device. When the power storage device is composed of two or more storage batteries, the power of the fuel cell is stored in one storage battery during the heat treatment by passing a current through the high resistance layer of the current collector. This is preferable because the battery can be operated.

  Examples of the power storage device include secondary batteries such as lithium ion secondary batteries, nickel hydride secondary batteries, proton batteries, and conductive polymer batteries, capacitors, and the like. Further, the power storage device can be provided, for example, in a manner similar to power storage device 94 shown in FIGS.

  FIG. 16 is a circuit diagram showing an aspect of a temperature control unit provided as a control unit of the fuel cell system of the present invention. As the temperature control unit, for example, a thermistor having a PTC (POSITIVE TEMPERATURE COEFFICIENT) characteristic is installed as a temperature sensor at a position where the temperature is to be sensed, and the transistor switch is turned on / off at a predetermined temperature by the resistance change of the thermistor. A circuit assembled so as to be able to be turned off can be employed.

  With reference to FIG. 16, a method for performing switch switching as to whether or not a current is passed through the high resistance layer and the low resistance layer using switches as shown in FIGS. In the following, a case where the switch is switched when the temperature detected by the temperature sensor is 40 ° C. or higher will be described as an example. However, the present invention is not limited to this. First, a constant voltage 46 of −5V is created from the secondary battery. The gate-source potential of the FET transistor 36 is determined by the divided voltage of the resistor 56 b and the thermistor 16. The resistance value of the thermistor 16 increases as the temperature rises, and turns on when the gate-source potential is about 2 V or more. The thermistor 16 has a characteristic of 470Ω at 25 ° C. and 4.7 kΩ at 45 ° C. The resistor 56b is 3 kΩ. Below about 40 ° C., the resistance value of the thermistor 16 is 4.5Ω or less, and the gate voltage is 2V or more due to the partial voltage of the resistor 56b. Therefore, the MOSFET 36 is turned on, and −5V is applied to the gate voltage of the MOSFET 26. Therefore, the MOSFET 26 is turned on. Here, the MOSFET 26 is a MOSFET which is turned on when the gate-source voltage is about −2V. The resistor 56a is 100 kΩ. This makes it possible to automatically control the switching of the switch when the current flows through the high resistance layer and when the current does not flow at a temperature of 40 ° C. depending on the temperature. By the method as described above, the input terminal 66 and the output terminal 76 can be controlled to be electrically connected at a predetermined temperature or higher set in advance.

<Control method of fuel cell system>
The present invention is also a method for controlling any one of the above-described fuel cell systems, the step of detecting at least one of the temperature of the anode and / or cathode electrode of the fuel cell and the outside air temperature by a temperature sensor; And a step of controlling the switch unit by the control unit based on the detection result and energizing a layer other than the low-resistance layer in the current collector, and passing an electric current through the layer other than the low-resistance layer, The present invention also relates to a method for controlling a fuel cell system that raises the temperature of a cathode electrode. Typically, when the temperature of the anode electrode and / or the cathode electrode or the outside air temperature is lower than a predetermined temperature set in advance, the temperature of the anode electrode and / or the cathode electrode is set by energizing layers other than the low resistance layer. Raise. In this case, when the temperature of the anode electrode and / or cathode electrode or the outside air temperature reaches the predetermined temperature, energization to layers other than the low resistance layer may be stopped.

  FIGS. 17 to 20 are flowcharts illustrating an example of a control mode of the fuel cell in the present invention. Below, the aspect of control of the fuel cell in the operation of an external device using the fuel cell as a power source will be described.

(Embodiment 10)
First, a control flow of the fuel cell when using the fuel cell system shown in FIG. 13 will be described with reference to FIG. When the fuel cell is activated and the temperature sensor 91 and the control unit 92 determine whether or not the temperature near the anode electrode is equal to or higher than a predetermined temperature A set in advance (step S102), the temperature near the anode electrode is the predetermined temperature A. If the temperature is lower (NO in step S102), the process proceeds to heat treatment 1 (step S104). If the temperature is equal to or higher than the predetermined temperature A (YES in step S102), the controller 92 switches 441, 445. Is turned off, the switches 442 and 444 are turned on, and the routine proceeds to a steady operation of supplying the power collected by the low resistance layer 303b to an external device (step S106).

  The heat treatment 1 is performed as follows. That is, the control unit 92 turns on the first and third switch elements connected to the high resistance layer 303a shown as switches 441 and 445, and connects the first and third switch elements shown as switches 442 and 444 to the low resistance layer 303b. By turning off the second and fourth switching elements and causing a current to flow through the high resistance layer 303a, the high resistance layer 303a generates heat due to the resistance loss of the current and is collected from the low resistance layer 303b through the high resistance layer 303a. Supply power to external devices. The heat of the high resistance layer 303a is quickly transferred to the low resistance layer 303b, and the electrode and the electrolyte layer are heated. When the temperature in the vicinity of the anode electrode becomes equal to or higher than the predetermined temperature A by heat treatment 1 (YES in step S102), the switch is switched by the control unit 96, and the routine proceeds to the above-described steady operation (step S106). In the steady operation (step S106), the external device is operated by the fuel cell (step S108). When an external device is operated by power generation of the fuel cell, the temperature of the fuel cell may gradually decrease depending on the outside air temperature. The process proceeds to the determination by the temperature sensor 91 and the controller 92 (step S110) as to whether or not the temperature in the vicinity of the anode electrode is equal to or higher than the predetermined temperature B set in advance as a temperature lower than the above-described predetermined temperature A. If the temperature is lower than the predetermined temperature B (NO in step S110), the process returns to step S102. If the temperature is equal to or higher than the predetermined temperature B (YES in step S110), the fuel cell continues to be external. The device is operated (step S108).

  Here, it is preferable that the predetermined temperature A is set within a range of 40 to 60 ° C., for example. The predetermined temperature B is preferably a temperature that can normally be reached at the lowest operating environment temperature, that is, an environmental temperature of −5 ° C., and can be set within a range of 20 to 30 ° C., for example.

(Embodiment 11)
The direct methanol fuel cell has a problem that water freezes when the outside air temperature becomes 0 ° C. or lower. In particular, water generated at the cathode and moisture in the electrolyte layer are problematic. When water produced at the cathode or water in the electrolyte layer freezes, the ionic conductivity decreases. In addition, the durability of the electrolyte layer and MEA is also impaired by expansion and contraction due to freezing of water. At a light load such as during standby or when the vehicle is stopped, the fuel cell temperature decreases due to a small amount of self-heating of the fuel cell.

  In the present invention, for example, an operation state monitor such as the operation state monitor 93 of FIG. 14 determines the operation state such as whether the external device is in a standby state, a stop state, or a steady operation state. It is preferable to maintain the temperature of the battery, particularly in the vicinity of the electrode and the electrolyte layer, within a predetermined range. The operating state can be determined by monitoring the output current and / or output voltage of the fuel cell and determining whether or not the output current and / or output voltage is equal to or higher than a predetermined value by the control unit. .

  With reference to FIG. 18 and FIG. 19, the control flow of the operation state when using the fuel cell system shown in FIG. 14 will be described.

  Referring to FIG. 18, in a steady state, the control unit 96 turns on the switches connected to the low resistance layer 303b, which are shown as the switches 442a, 444a, 444b, and 444c in FIG. 14, and the switches 441a, 445a, 445b, and 445c are turned on. By turning off the switch connected to the high resistance layer 303a shown, the power collected from the low resistance layer 303b is supplied to the device, and the device is operated by the fuel cell (step S202). During operation, when the operation state monitor 93 and the control unit 96 determine whether or not to wait (step S204), if it is standby (YES in step S204), the process proceeds to standby (step S208). If it is not during standby (NO in step S204), the process proceeds to determination (S206) of whether the temperature in the vicinity of the anode electrode is equal to or higher than the predetermined temperature B by the temperature sensor 91 and the control unit 96. When the temperature near the anode electrode is equal to or higher than the predetermined temperature B (YES in step S206), the device is operated with the fuel cell (step S202), and when the temperature near the anode electrode is lower than the predetermined temperature B (in step S206, NO), the process proceeds to heat treatment 1 (step S214).

  The heat treatment 1 is performed by turning on the switch connected to the high resistance layer 303a and turning off the switch connected to the low resistance layer 303b, as in the method described above with reference to FIG. After the heat treatment 1, the process proceeds to the determination (S216) of whether or not the temperature near the anode electrode is equal to or higher than the predetermined temperature A by the temperature sensor 91 and the control unit 96. When the temperature in the vicinity of the anode electrode is equal to or higher than the predetermined temperature A (YES in step S216), the process returns to the operation of the external device in the fuel cell (step S202), and the temperature in the vicinity of the anode electrode is lower than the predetermined temperature A (step In S216, NO), and the above heat treatment 1 (S214) is performed until the temperature in the vicinity of the anode electrode becomes equal to or higher than the predetermined temperature A.

  After the transition to the standby time (step S208), in FIG. 19, when the operation state monitor 93 and the control unit 96 determine whether or not it is in the steady state (step S302), if it is not in the steady state (NO in step S302), the anode The process proceeds to determination (step S304) by the temperature sensor 91 and the control unit 96 as to whether or not the temperature in the vicinity of the electrode is equal to or higher than a predetermined temperature C set in advance. If the temperature in the vicinity of the anode electrode is equal to or higher than the predetermined temperature C (YES in step S304), the process returns to the determination (step S302) as to whether the temperature is normal. On the other hand, when the determination in step S302 is a steady operation (YES in step S302), the process returns to the steady state (step S306). When the temperature in the vicinity of the anode electrode is lower than the predetermined temperature C (NO in step S304), a signal is sent to the control unit 96, and the process proceeds to heat treatment 2 (step S308).

  Heat treatment 2 during standby is performed as follows. That is, the control unit 96 turns on the switches 443a, 443b, 443c, 447a, 447b, 447c and turns off the other switches, and the power collected by the high resistance layer 303a is supplied from the fuel cell to one of the power storage devices 94. The storage battery is charged with a constant current by stepping up or down to a charge voltage or higher by a charge / discharge circuit 95. As the amount of power generated by the fuel cell increases, the fuel cell is further heated by self-heating and heat generation due to resistance loss in the high resistance layer. The heat treatment 2 is controlled by the control unit 96 so as to be performed for a predetermined time set in advance.

  As the predetermined time elapses, the controller 96 switches off the switch that was turned on in the heat treatment 2 and ends the heat treatment 2 (step S308). When the operation state monitor 93 and the control unit 96 determine whether or not it is in a steady state (step S310), if it is in a steady state (YES in step S310), return to the steady state (step S306), and not in a steady state (step S310). In S310, NO), the process proceeds to determination (step S312) by the temperature sensor 91 and the control unit 96 whether or not the vicinity of the anode electrode is equal to or higher than a predetermined temperature D set in advance. If the temperature in the vicinity of the anode electrode is equal to or higher than the predetermined temperature D (YES in step S312), the process returns to the determination of whether or not it is stationary (step S302), and the temperature in the vicinity of the anode electrode is lower than the predetermined temperature D ( In step S312, NO, the process returns to heat treatment 2 (step S308). When returning to the normal state (step S306) as described above, the control proceeds to the control in the flowchart shown in FIG. 18 through the return from the standby state shown in FIG. 18 (step S210). In the manner described above, temperature control in the vicinity of the anode electrode can be performed during normal operation and standby.

  In the present invention, the predetermined temperature C is preferably 5 to 9 ° C. Moreover, as the predetermined temperature D, about 10-13 degreeC is preferable. When the predetermined temperature C and the predetermined temperature D are set within the above ranges, water freezing inside the fuel cell is well prevented, and the power consumption of the fuel cell during standby is reduced to reduce power generation efficiency. Can be prevented.

  In addition, the aspect of said heat processing 1 (step S214) in case the fuel cell system of this invention is equipped with an electrical storage apparatus is demonstrated to the case of the fuel cell system shown by FIG. 14 as an example. That is, the control unit 96 turns on the switches 441a, 445a, 445b, 445c, 447a, and 447c, and turns off the other switches so that a current flows through the high resistance layer 303a and heats the high resistance layer 303a. One of the storage batteries 94 of the storage battery 94 is charged. Which storage battery is charged is determined by controlling the charge / discharge circuit 95 by the control unit 96.

  The state of charge of the storage battery being charged in the power storage device 94 is monitored by the open / close voltage by the charge / discharge circuit 95, and if charged to 90% or more, the control unit 96 determines the other storage battery being charged and the charging target. Switch. When all the storage batteries are charged to 90% or more and the charging current from the fuel cell stops flowing beyond a predetermined value, the charging / discharging circuit 95 cuts off the charging current and stops the output from the fuel cell to the device. When the external device is not operating (YES in step S204), the process proceeds to the control in the flowchart shown in FIG. When the external device is in the standby state, the switches 441a, 445c, 443a, 446a, 443b, 446b, 443c, 446c, 447a, 448a, 447b, 448b, 447c, 448c are turned on, and the other switches are turned off. Electric power is supplied from the power storage device to the device and the high resistance layer 303a. When the voltage of the power storage device monitored by the charge / discharge circuit 95 and transmitted to the control unit 96 becomes equal to or lower than a predetermined voltage set in advance, the control unit 96 switches the switch and restarts the heat treatment and power storage by the fuel cell. To do.

  In the present invention, when the heat treatment 1 is performed, a hybrid system that supplies both the power of the power storage device and the fuel cell to the device may be employed. In this case, the switches 441a, 445a, 445b, 445c, 447a, 449c are turned on, and the other switches are turned off. The charging / discharging circuit 95 controls to supply power from the storage battery that is insufficient to operate the external device with the output from the fuel cell.

  In addition, when an output exceeding the power consumption of the external device can be taken out from the fuel cell in a steady state, the switches 442a, 444a, 444b, 444c, 447a, 446c are turned on and the other switches are turned off. It is preferable to store power in the power storage device 94.

  If no current can be taken from the fuel cell at startup, the switches 443a, 446a, 443b, 446b, 443c, 446c, 447a, 448a, 447b, 448b, 447c, 448c are turned on and the other switches are turned off. It is preferable to pass a current from the power storage device 94 to the high resistance layer 303a to quickly raise the temperature of the fuel cell.

  In the present invention, when performing the heat treatment for a predetermined time, it is preferable to apply a limiter by a temperature sensor so that the heat treatment can be temporarily interrupted when the vicinity of the electrode and the electrolyte layer becomes too high. In this case, it is preferable to supply the shortage of power supplied to the device from the power storage device while the limiter is activated and the heat treatment is interrupted. As the limiter, for example, by turning off both of the switches 441a and 442a which are the switches of the output terminals of the fuel cell, the output current of the fuel cell is prevented from flowing, and the output current is interrupted by the charge / discharge circuit 95. Examples include a configuration in which the heat treatment is interrupted and a configuration in which the current is switched to flow through the low resistance layer.

(Embodiment 12)
In the present invention, when the outside air temperature is lower than a predetermined temperature set in advance, the temperature of the anode electrode and / or the cathode electrode is raised by flowing a current through the high resistance layer, and the current flows when the outside air temperature reaches the predetermined temperature. The fuel cell system may be controlled by stopping the flow. In this case, the fuel cell may be controlled in the same manner as described above except that the temperature sensor is installed in the outside air to monitor the outside air temperature.

(Embodiment 13)
In the present invention, the current may be controlled to flow through the high resistance layer when the temperature difference value obtained by subtracting the anode electrode temperature from the cathode electrode temperature is lower than a predetermined value set in advance. In this case, the current flow may be stopped when the temperature difference value reaches a predetermined value. In the present invention, when the cathode electrode is at a higher temperature than the anode electrode and the temperature difference between the two electrodes is maintained at a predetermined value or more, water or water vapor generated on the cathode side, water diffused from the anode side to the cathode side, and The amount of water that is generated by oxidation of the crossover methanol and returns to the electrolyte layer due to the vapor pressure difference between the anode side and cathode side water and moves from the cathode side to the anode side through the electrolyte layer Can be increased. This control not only improves the power generation efficiency due to the temperature rise described above, but also moves the water on the cathode side to the anode side, thereby reducing the methanol concentration in the catalyst layer of the anode electrode and reducing the power generation characteristics due to crossover. And the power generation efficiency of the fuel cell is improved. Also, by reusing the water generated on the cathode side for the reaction on the anode side, it becomes possible to reduce the amount of water contained in the anode-side fuel container prepared in advance, making the fuel container smaller and lighter And the output density and energy density of the entire fuel cell system can be improved.

  In order to make the value of the temperature difference obtained by subtracting the temperature of the anode electrode from the temperature of the cathode electrode equal to or greater than a predetermined value, the above-described temperature sensors are installed in the vicinity of the anode electrode and the cathode electrode. The temperature of each electrode is monitored, and when the temperature difference is lower than a predetermined value, a current is passed through the high-resistance layer of the current collector on the cathode side to raise the temperature of the cathode electrode, thereby The difference can be greater than or equal to a predetermined value. The temperature difference is preferably set to about 10 to 15 ° C. The heat treatment of the cathode electrode is preferably performed intermittently at a predetermined operation timing for a predetermined operation time.

  The intermittent heat treatment can be performed as follows, for example. That is, after heat treatment is performed to set the temperature difference value to 10 ° C. or more, the heat treatment is continued for 1 minute so that the temperature difference value does not become 10 ° C. or less. The heat treatment is stopped after 1 minute, and the heat treatment is not performed for 5 minutes, and the operation is performed in a steady operation. By repeating the above operation, intermittent heat treatment can be performed.

(Embodiment 14)
In the present invention, the output current and / or output voltage of the fuel cell is detected by the monitor unit, and when the value of the output current and / or output voltage is lower than a predetermined value, a current is passed through the high resistance layer. Thus, the temperature of the anode electrode and / or the cathode electrode may be controlled to increase. In this case, the current flow may be stopped when the above value reaches a predetermined value. According to such control, during operation of the fuel cell, the output current and / or output voltage can be maintained at a predetermined value or more, and a stable output from the fuel cell to the external device can be obtained.

  Specifically, the output current and / or output voltage of the fuel cell is constantly monitored, and when the value of the output current and / or output voltage is equal to or greater than a predetermined value, the current is taken out from the low resistance layer of the current collector, When the value of the output current and / or output voltage is lower than a predetermined value, it is preferable to switch the current to flow through the high resistance layer for a predetermined time to increase the temperature in the vicinity of the electrode and the electrolyte layer.

  With reference to FIG. 20, the control flow of the operation state by monitoring the single cell voltage using the fuel cell system shown in FIG.

  In FIG. 20, at the time of steady operation, the device is operated with the fuel cell (step S402). During operation, when the monitor unit 97 and the control unit 98 determine whether the single cell voltage is equal to or higher than a predetermined value V1 (step S404), the single cell voltage is equal to or higher than the predetermined value V1 (step S404). In step S404, YES), the process proceeds to the determination (step S410) as to whether or not the operation state monitor 93 and the control unit 98 are on standby. If the single cell voltage is lower than the predetermined value V1 (NO in step S404), the process proceeds to heat treatment 2 (step S502). Heat treatment 2 is performed in the same manner as described in FIG.

  The heating process 2 is performed (step S502), and the process proceeds to the determination (step S504) as to whether the operation state monitor 93 and the control unit 98 are on standby. If the determination is standby (YES in step S504), the heating process is performed. 2 is terminated and the process proceeds to the standby state (step S506). If the standby state is not reached (NO in step S504), the control unit 98 proceeds to the determination of whether or not the predetermined time E has elapsed (step S508). When the predetermined time E has elapsed (YES in step S508), the process proceeds to determination (step S406) whether or not the single cell voltage is equal to or higher than the predetermined voltage V1. If the predetermined time E has not elapsed (NO in step S508), the process returns to heat treatment 2 (step S502).

  If the single cell voltage is equal to or higher than the predetermined value V1 (YES in step S406), the operation state monitor 93 and the control unit 98 proceed to the determination of whether or not the standby state (step S410), and the single cell voltage is the predetermined value V1. If it is lower (NO in step S406), it is determined as abnormal and the system is stopped (step S412). If it is determined whether or not it is in standby (step S410) and it is in standby (YES in step S410), it shifts to standby (step S414). If it is not in standby (NO in step S410), the vicinity of the anode electrode When the temperature of the anode electrode is equal to or higher than the aforementioned predetermined temperature B, the process proceeds to a determination by the temperature sensor (not shown) and the control unit 98 (step S416). When the device is operated with the fuel cell (step S402) and the temperature near the anode electrode is lower than the predetermined temperature B (NO in step S416), the temperature near the anode electrode is equal to or higher than the predetermined temperature A. The process proceeds to the determination by the temperature sensor and control unit 98 (step S418). When the temperature near the anode electrode is equal to or higher than the predetermined temperature A (YES in step S418), the device is operated with the fuel cell (step S402), and when the temperature near the anode electrode is lower than the predetermined temperature A (step S418). In NO, the process proceeds to heat treatment 1 (step S420). Heat treatment 1 is performed in the same manner as described above with reference to FIG. In the determination (step S420) of whether or not the operation state monitor 93 and the control unit 98 are on standby (step S420: YES), the process shifts to standby (step S422) and is not on standby (step S420). In step S420, NO), the process returns to the determination (step S418) of whether or not the temperature in the vicinity of the anode electrode is equal to or higher than the predetermined temperature A.

  In the case of shifting to the standby time (step S414, step S422), the same control as described above with reference to FIG. 19 is performed. In FIG. 19, when it is determined that the time is steady (YES in step S302 or YES in step S310), the process returns to the steady state (step S306), and the process returns from the standby state in FIG. 20 (step S424). Then, the control shifts to the flowchart shown in FIG.

  The predetermined voltage V1 can be set to about 0.2V ± 0.05V, for example. The predetermined time E can be set to about 5 to 10 minutes, for example.

  In the present invention, the heat treatment 1 and the heat treatment 2 may be performed by, for example, a method of alternately heating the anode side and the cathode side by the following method. That is, as the heating on the anode side, only the switches connected to the high resistance layer on the anode side, which are shown as switches 443a, 443b, 443c, 447a, 447b, and 447c, are turned on, and the other switches are turned off. Current is passed through the high resistance layer on the side. Next, as the heating on the cathode side, only the switches connected to the high-resistance layer on the cathode side, which are indicated as switches 446a, 446b, 446c, 448a, 448b, and 448c, are turned on, and the other switches are turned off. Current is passed through the high resistance layer on the side. In addition, the switches 441a, 444a, 445b, and 444c are turned on for output, and the switches 442a, 445a, 444b, and 445c are turned on for output, and the switches are switched at predetermined time intervals. The anode side and the cathode side may be alternately heated. By repeating the above switch switching, heating of the anode side and the cathode side can be performed alternately.

  In the present invention, when the fuel cell system includes a power storage device, power storage in the power storage device may be performed when the device is lightly loaded, stopped, or terminated. In the present invention, when a heater is provided in the fuel cell, it is preferable to connect a switch that is controlled to be turned on / off simultaneously with energization to the high resistance layer.

  In addition, as the heat treatment during standby of the external device in the present invention, for example, control by an output voltage monitor may be performed in addition to the control by the set temperature as shown in FIG.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these.

[Example 1]
As the electrolyte layer, a Nafion (registered trademark) 117 membrane (manufactured by DuPont) having a size of 30 mm × 30 mm and a thickness of about 175 μm was used.

  The catalyst paste was prepared by the following procedure. Catalyst-supported carbon particles (TEC66E50, manufactured by Tanaka Kikinzoku Co., Ltd.) comprising Pt-Ru particles and carbon particles having a Pt-supported amount of 32.5 wt% and a Ru-supported amount of 16.9 wt%, and 20 wt% of Nafion (registered trademark) alcohol An anode catalyst paste was prepared by putting a solution (manufactured by Aldrich), isopropanol, and alumina balls into a PTFE container at a predetermined ratio and mixing them at 500 rpm for 50 minutes using a stirrer.

  In addition, a cathode catalyst paste was prepared in the same manner as the anode catalyst paste described above, using catalyst-supported carbon particles (TEC10E50E, manufactured by Tanaka Kikinzoku Co., Ltd.) comprising Pt particles having a Pt support amount of 46.8 wt% and carbon particles. .

  As a current collector, a platinum plate with a thickness of 1 μm is formed by opening a diamond-shaped through-hole having a thickness of 0.5 mm, a width of 1 mm, a width of 1.5 mm, and a length of 0.75 mm on a Ti plate having a thickness of 100 μm. And a current collector made of a laminate of a low resistance layer made of Ti and a high resistance layer not plated on a titanium mesh made of a wire mesh (100 mesh) having a wire diameter of 30 μm. As an insulating layer, a polyimide coating material was applied to a titanium mesh which is a high resistance layer and cured. Cure is performed at a temperature of 3.5 ° C./minute and held at 170 ° C. for 30 minutes, then at a temperature of 3.5 ° C./minute and held at 320 ° C. for 60 minutes, and then cooled to room temperature. It was. With solder, the ends of the high resistance layer and the low resistance layer were joined to form a joining member, and further, a polyimide resin was coated to seal the solder joint, thereby obtaining an insulating sealing portion. The metal lath was processed by a processor (Sunk Metal Co., Ltd.).

The resistance value of the high resistance layer is 170 mΩ, which is a resistance when a terminal is attached to each of two opposite sides of a 1 cm ² square and a current is passed in a plane direction, that is, a sheet resistance per 1 cm ^{2 of} area. The resistance value of the layer was 16 mΩ as the sheet resistance. The end of the current collector was a current extraction part.

GDL31BC (manufactured by SGL Carbon Japan Co., Ltd.), which is a carbon gas diffusion layer, is used as a porous substrate with a size of 23 mm × 23 mm, and the GDL31BC and the surface on the high resistance layer side of the current collector are laminated to face each other. The GDL31BC and the current collector were pressed and integrated at 1 t / cm ² . In this way, two integrated products are formed, and the anode catalyst paste is 100 μm thick on the one integrated current collector and the cathode catalyst paste on the other integrated current collector. Were coated in a thickness of 20 μm to form an anode electrode and a cathode electrode.

GDL31BC, current collector, anode electrode, Nafion (registered trademark) 117, cathode electrode, current collector, and GDL31BC were laminated in this order to produce a laminate. GDL31BC was arranged to coincide with the electrode formation region. The electrode side surface of GDL31BC is a carbon porous body having water repellency. This laminate was hot pressed at 130 ° C. and 10 kgf / cm ² for 2 minutes. Thus, a membrane electrode assembly having a structure in which a current collector is embedded in the catalyst layer and a carbon gas diffusion layer is provided so as to face the electrolyte layer with the current collector interposed therebetween can be obtained. Produced.

  An anode for supplying fuel and air between the anode diffusion layer and the cathode diffusion layer and the separator by sandwiching the outside of the membrane electrode assembly with an insulating separator made of polyacrylic resin A fuel channel and a cathode fuel channel were provided. A heater was installed at the position of the wall surface of the anode inside the separator and integrated with the separator. As the heater, an electric resistance heater in which the surface of the nichrome wire was coated with a corrosion-resistant resin was used. A unit cell of a fuel cell was produced by the above method. 10 cells were stacked in series connection to form a stack.

  A fuel cell system was constructed so as to be the same as the configuration shown in FIG. 13 except that the fuel cell produced above was used.

  When the constructed fuel cell system is started up, electric power is output from the fuel cell, the high resistance layer is energized and heated, and the heating time from the start to the anode electrode temperature of 40 ° C. is measured. The heating time was shortened to about 1/10 compared with the case of using the fuel cell of Conventional Example 1 described later. In this embodiment, the titanium mesh that is the high resistance layer is coated with the polyimide resin that is the insulating layer, and thus is not in contact with the catalyst layer of the electrode. Further, the high resistance layer and the low resistance layer are insulated by the polyimide resin except for the soldered portion. In this embodiment, the Ti—Au plate, which is a low resistance layer, is prevented from being electrically short-circuited by the catalyst layer other than the soldered portion, and therefore the catalyst layer of the electrode is effectively heated.

[Conventional example 1]
As Conventional Example 1, a fuel cell was manufactured as follows. The same anode catalyst paste and cathode catalyst paste as in Example 1 were used. GDL31BC (manufactured by SGL Carbon Japan Co., Ltd.), which is the same carbon gas diffusion layer as in Example 1, was used as a porous substrate having a size of 23 mm × 23 mm, and an anode catalyst paste and a cathode catalyst paste were respectively applied onto GDL31BC. Then, an electrode was formed. As the electrolyte layer, a Nafion (registered trademark) 117 membrane (manufactured by DuPont) having a size of 30 mm × 30 mm and a thickness of about 175 μm was used. GDL31BC, anode electrode, Nafion (registered trademark) 117, cathode electrode, and GDL31BC were laminated in this order. GDL31BC was arranged to match the electrode. The electrode-side surface of GDL31BC is a carbon porous body having water repellency. The laminated body was hot-pressed at 130 ° C. and 10 kgf / cm ² for 2 minutes to produce a membrane electrode assembly. This membrane electrode assembly is sandwiched between carbon anodes having a shape shown in FIG. 21 where fuel and air flow paths are configured for both the anode and cathode, and each member is fixed using bolts and nuts. The fuel cell stack was concluded. As the carbon separator, a carbon separator having a size of 4 × 4 cm, a depth of the anode flow path and the cathode flow path of 1 mm, and a width between the flow paths of 2 mm was laminated by stacking 10 cells. A heating wire heater was provided on the outer periphery of the stack, and a temperature sensor was also provided in the vicinity of the anode electrode of each cell. The fuel cell was produced by the above method, and the heating time from when the fuel cell was started until the temperature of the anode electrode reached 40 ° C. was measured.

[Example 2]
In this example, an insulating layer laminated on a current collector is joined to an electrolyte layer, and an anode electrode, a cathode electrode, an anode diffusion layer, and a cathode diffusion layer are disposed thereon, thereby forming a membrane electrode assembly, a collector. A fuel cell having a structure in which an electric body and a diffusion layer were joined was fabricated.

  The current collector is a 150 μm thick Ti plate with 0.5 mm vertical, 1 mm horizontal, 1.5 mm horizontal pitch, 0.75 mm vertical through holes, and platinum plated with a thickness of 1 μm. A current collector made of a laminate of a low-resistance layer and a high-resistance layer in which platinum is plated with a thickness of 100 nm on a titanium mesh made of metal lath (100 mesh) having a line width of 30 μm was used. After the polyimide resin is thinly applied to the current collector, a porous polyimide sheet having a thickness of 50 μm is sandwiched as an insulating layer between the high resistance layer and the low resistance layer, and the polyimide is thermally cured to reduce the resistance between the high resistance layer and the low resistance layer. The resistance layer was joined. As the insulating layer, one having a through hole having the same shape as that of the low resistance layer was used, and the above bonding was performed in a state where the positions of the through holes of the low resistance layer and the insulating layer were aligned.

  In the same manner as shown in FIG. 3, the above-mentioned joining is performed so as to have regions not joined to the electrodes at both ends of the current collector, with one end serving as a current extraction portion and the other end serving as a high resistance layer and a low resistance. An electrical junction with the layer was made. That is, at the other end, the high resistance layer and the low resistance layer were joined by solder as a joining member. The solder was coated with a polyimide resin in order to prevent corrosion and to improve the peel strength in the vicinity of the take-out part. An insulating sealing portion was provided around the joining member so that the fuel liquid did not contact the joining member.

  As shown in FIGS. 8 and 9, the porous polyimide sheet protruding from the end of the current collector was joined to the electrolyte layer using an adhesive. That is, after applying a phenol resin, which is an adhesive that is thermally cured at 150 ° C., hot pressing was performed at 150 ° C. for 10 minutes, and the pressed state was cooled to room temperature and bonded. Thereafter, an anode catalyst paste and a cathode catalyst paste prepared in the same manner as in Example 1 were applied and dried to form an anode catalyst layer and a cathode catalyst layer, and then GDL31BC, which is a carbon gas diffusion layer, was added to the anode catalyst layer. It was laminated on the catalyst layer and the cathode catalyst layer, and integrated by hot pressing at 130 ° C. for 2 minutes.

  When the heating time from the construction and start-up of the fuel cell system to the temperature of the anode electrode reaching 40 ° C. was measured in the same manner as in Example 1 except for the members described above, a result of about 2 minutes was obtained. In this embodiment, since the current collector and the electrolyte layer are firmly bonded with an adhesive via an insulating layer, peeling due to swelling and shrinkage due to temperature change is unlikely to occur.

[Example 3]
The current collector is a 150 μm thick Ti plate with 0.5 mm vertical, 1 mm horizontal, 1.5 mm horizontal pitch, 0.75 mm vertical through holes, and platinum plated with a thickness of 1 μm. And a current collector made of a laminate of a low resistance layer made of Ti and a high resistance layer not plated on a titanium mesh made of a wire mesh (100 mesh) having a wire diameter of 30 μm. As an insulating layer, a polyarylene ether sulfonic acid resin that is an electrolyte polymer was applied to a titanium mesh that was a high resistance layer and dried at 150 ° C. The end portions of the high resistance layer and the low resistance layer were joined with solder, and the PVDF resin was coated to seal the solder joint portion. The resistance value of the high resistance layer was 170 mΩ as a sheet resistance of 1 cm ² measured by the same method as described above, and the resistance value of the low resistance layer was 16 mΩ as the sheet resistance. The end of the current collector was a current extraction part.

The high resistance layer side coated with the polyarylene ether sulfonic acid resin is laminated on the insulating layer made of the same kind of polyarylene ether sulfonic acid resin as that used for the electrolyte layer, and 150 kg, 5 minutes, 10 kgf / cm ^2. The electrolyte layer, the current collector, and the insulating layer were joined by hot pressing under the conditions described above. By being made of the same kind of polymer, the electrolyte layer and the insulating layer were well adhered and adhered. From this, a membrane electrode assembly was produced in the same manner as in Example 2.

  When the heating time from the construction and start-up of the fuel cell system to the temperature of the anode electrode reaching 40 ° C. was measured in the same manner as in Example 1 except for the members described above, a result of about 2 minutes was obtained.

[Example 4]
A high resistance layer was produced by the following method. A P-type silicon substrate with holes formed by wet etching is prepared, adjusted to a size of 25 cm × 25 cm by dicing, and, as shown in FIG. 6, P having a thickness of 1000 μm and 0.01 Ω · cm A through-hole having a diameter of 100 μm was formed in the mold silicon substrate to produce a substrate 15. The through holes were opened at a pitch of 200 μm so as to provide hexagonal closest packing. Gold was deposited as metal layers 25 and 35 on a part of the region of the substrate 15 by sputtering. Further, the surface of the substrate 15 was oxidized to insulate portions other than gold. The oxidation treatment was performed by heating at 900 ° C. for 3 hours in dry oxygen to form an oxide layer 45 having a thickness of about 100 nm.

  Next, a low resistance layer was produced by the following method. A metal foil 55 was laminated on the surface of the oxidized substrate. In this example, the metal foil 55 was formed by plating the surface of a P-type silicon substrate with gold (Au) to a thickness of 0.2 μm and laminating 100 μm of a titanium foil whose surface was further treated. In the titanium foil, a through hole having the same shape as the through hole formed in the P-type silicon substrate was formed by drilling. Next, the metal layer 35 and the surface of the low resistance layer on which gold was formed were joined by solder. The solder part was coated with polyimide resin. Each of the two current extraction units 65 and 75 is provided with a switch. The metal foil 55 was brought into contact with the catalyst layer surface of the membrane electrode assembly.

The resistance value of the high resistance layer was 200 mΩ with a sheet resistance of 1 cm ² , and the resistance value of the low resistance layer was 18 mΩ with a sheet resistance.

  When the heating time from the construction and start-up of the fuel cell system to the temperature of the anode electrode reaching 40 ° C. was measured in the same manner as in Example 1 except for the members described above, a result of about 2 minutes was obtained.

[Example 5]
Using the fuel cell produced in Example 1, as shown in FIG. 15, at the ends of the low resistance layer (Ti lath-Pt layer) and the high resistance layer (Ti mesh layer) of the current collector, A fuel cell system including a temperature sensor, a control unit 98, a power storage device 94 including two secondary batteries, and a monitor unit 97 for monitoring the output voltage was constructed. A thermocouple was used as the temperature sensor. The catalyst temperature of the anode electrode was monitored by a temperature sensor. When the temperature was lower than 40 ° C. from the start, heat treatment 1 was performed as follows.

  The switches connected to the high resistance layer indicated by the switches 441a, 445a, 445b, and 445c are turned on, the switches connected to the low resistance layer indicated by the switches 442a, 444a, 444b, and 444c are turned off, and current is supplied to the high resistance layer 303a. By flowing, heat was generated due to resistance loss of current.

  At the time of startup, the switch 447a and the switch 446c connected to the high resistance layer of the endmost cell and the switches 445a and 445b are turned on, and the charge / discharge circuit is connected from the fuel cell to one of the secondary batteries of the power storage device 94. One side was charged with a constant current at 95. In the meantime, the switches 441a, 442a, 444c, and 445c were turned off, and the device was supplied from the other secondary battery of the power storage device 94.

  In the fuel cell of Conventional Example 1, it took about 20 minutes for the catalyst temperature to reach 40 ° C. at a constant current of 1.25 A at 25 ° C., but in this example, it reached 40 ° C. in about 2 minutes. .

  When the catalyst temperature reaches 40 ° C. or higher, the switches 447a and 446c are turned off, the switches connected to the low resistance layers indicated by the switches 442a, 444a, 444b, and 444c are turned on, and a current is passed through the low resistance layer 303b. Then, the operation was shifted to the steady operation of the fuel cell without passing a current through the high resistance layer 303a.

  The operation flow of the fuel cell follows FIG. From the time of startup, the temperature of the current collector portion was monitored, and when the catalyst temperature was less than 40 ° C., a current was passed through the high resistance layer 303a to charge the secondary battery as the power storage device. The instrument was activated by a secondary battery. When the catalyst temperature reached 40 ° C. or higher, the device was operated with a fuel cell. The separator is heat-insulating, and since the heat capacity inside the separator is small, the temperature drop of the catalyst portion is small. When the temperature dropped to 20 ° C., the secondary battery was heated again while being charged in the same manner as at startup. At that time, one secondary battery was charged with a constant current, and the device was operated with the other battery. When the secondary battery was fully charged, the secondary battery being discharged was exchanged for charge and discharge, and the discharged secondary battery was charged. The secondary battery was controlled by a method of monitoring the voltage of the secondary battery with a voltage monitor so that the secondary battery would not be charged until the voltage was lowered to the predetermined voltage V1. During that time, the fuel cell did not generate electricity and was in a standby state. When the secondary battery being discharged was equal to or lower than the predetermined voltage V1, the battery was charged so as to be between the predetermined voltage V2 (where V2> V1). The voltage of the secondary battery was monitored by a charge / discharge circuit. In this embodiment, the switch is on / off controlled by a power transistor.

  In addition, it was determined whether or not the catalyst temperature was 40 ° C. or higher, and the control when switching the transistor was performed by the following method.

  As shown in FIG. 16, a thermistor having PTC (POSITIVE TEMPERATURE COEFFICIENT) characteristics is installed at a position where temperature is desired to be sensed, and a circuit is constructed so that the switch of the transistor can be controlled on / off by changing its resistance.

  A constant voltage 46 of −5 V was created from the secondary battery. The gate-source potential of the MOSFET 36 is determined by the partial pressure of the resistor 56 b and the thermistor 16. The thermistor 16 increases in resistance as the temperature rises, and is turned on when the gate-source potential is about 2 V or more. As the thermistor 16, a thermistor having a characteristic of 470Ω at 25 ° C. and 4.7 kΩ at 45 ° C. was used. The resistor 56b was 3 kΩ. At about 40 ° C. or less, the thermistor is 4.5Ω or less, and the gate voltage is 2 V or more due to the resistance voltage division. Therefore, the MOSFET 36 is turned on, and −5 V is applied to the gate voltage of the MOSFET 26. Turn on. The MOSFET 26 is a MOSFET that is turned on when the gate-source voltage is about −2V. The resistor 56a was 100 kΩ. Thereby, it is possible to automatically control the switching of the switch at a temperature of 40 ° C. depending on the temperature when the current is passed through the high resistance portion and when the current is not passed.

  As described above, the temperature of the current collector can be quickly raised at the time of start-up, and high-efficiency power generation can be performed at a high temperature even in a steady state. The secondary battery was charged to a predetermined voltage when the external device was stopped. Thereby, it was possible to operate the external device with the secondary battery when the external device started up.

[Example 6]
In this example, a fuel cell having the configuration shown in FIG. 12 was produced. The current collector of the cathode electrode was composed of a cathode low resistance layer and a cathode high resistance layer, and an insulating layer was formed between both layers. The cathode current collector was produced in the same manner as in Example 2. The cathode current collector was pressed and pressed against the diffusion layer made of carbon GDL, and the cathode catalyst paste produced by the same method as in Example 1 was applied onto the cathode current collector to form a cathode catalyst layer. Thus, the cathode electrode was formed. The resistance value of the cathode high resistance layer was 170 mΩ as a sheet resistance of 1 cm ² measured by the same method as described above, and the resistance value of the cathode low resistance layer was 16 mΩ as the sheet resistance.

As the current collector for the anode electrode, an Au mesh having a diameter of 70 μm and 100 mesh was used as the anode low resistance layer. The resistance value of the anode low resistance layer was 11 mΩ in terms of the sheet resistance. A diffusion layer made of carbon GDL and an anode current collector were fixed by pressing, and then an anode catalyst paste was applied to form an anode catalyst layer. The anode electrode, the electrolyte layer made of Nafion (registered trademark) 117, and the cathode electrode are laminated in order of the electrode formation region of the anode electrode and the cathode electrode, and hot pressed at 130 ° C. and 10 kgf / cm ² for 2 minutes. The membrane electrode assembly was produced by processing.

  Further, the above membrane electrode assembly was sandwiched between a polyacrylic casing produced by cutting and the outer periphery was sealed with an epoxy resin, thereby producing a fuel cell shown in FIG.

  Using the fuel cell prepared above, the power generation characteristics at room temperature and 50% relative humidity were measured. The fuel cell was surrounded by an acrylic cover case, and a 3 mol / L aqueous methanol solution was supplied from the lower supply port so that the anode catalyst layer was completely immersed, and the cathode catalyst layer was opened to the atmosphere. Since no additional fuel was supplied, an extra 7 CC was supplied to the liquid level on the anode electrode side so that the fuel was immersed in all of the catalyst layer after power generation for 1 hour. A switch was provided so that current could flow independently through the high resistance layer and the low resistance layer of the current collector on the cathode side. At the time of steady operation of the fuel cell, the output is taken out from the low resistance layer using the low resistance layer as a current collector, and the current is passed through the high resistance layer of the cathode electrode by switching the switch for 1 minute every 5 minutes. The heat treatment was performed.

As a result, the power generation characteristic was 0.31 V at 100 mA / cm ² . In this state, the volume of fuel remaining on the anode electrode side after power generation for 1 hour was confirmed to be 6.11 CC.

  In addition, when the same cell as in Example 6 was used and only the current was passed through the low resistance layer, the volume of fuel remaining on the anode side after power generation for 1 hour was 5.62 CC. From the above results, according to the present invention, the water on the cathode side can be returned to the anode side and reused by a small fuel cell by a simple method. It turned out that the size of the fuel tank, such as a cartridge, can be reduced because it improves.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The fuel cell, the fuel cell system, and the control method for the fuel cell system of the present invention can be suitably applied to, for example, portable electronic devices.

It is sectional drawing which shows the example of a structure of the fuel cell of this invention. It is sectional drawing which shows the example of a structure of the fuel cell of this invention. It is a top view explaining the example of a structure of the electrical power collector in the fuel cell of this invention. It is a top view explaining the example of a structure of the electrical power collector in the fuel cell of this invention. It is a top view explaining the example of a structure of the electrical power collector in the fuel cell of this invention. It is a figure explaining the manufacturing method of the electrical power collector which has a through-hole. It is a top view explaining the example of a structure of the electrical power collector in the fuel cell of this invention. It is a top view explaining the example of a structure of the electrical power collector in the fuel cell of this invention. It is sectional drawing which shows the IX-IX cross section of FIG. It is a top view explaining the example of a structure of the electrical power collector in the fuel cell of this invention. It is sectional drawing which shows the XI-XI cross section of FIG. It is sectional drawing which shows the structure of the fuel cell of this invention. It is a figure explaining the example of the fuel cell system of this invention. It is a figure explaining the example of the fuel cell system of this invention. It is a figure explaining the example of the fuel cell system of this invention. It is a circuit diagram which shows the one aspect | mode of the temperature control part provided as a control part of the fuel cell system of this invention. It is a figure which shows the flowchart explaining the example of the aspect of control of the fuel cell in this invention. It is a figure which shows the flowchart explaining the example of the aspect of control of the fuel cell in this invention. It is a figure which shows the flowchart explaining the example of the aspect of control of the fuel cell in this invention. It is a figure which shows the flowchart explaining the example of the aspect of control of the fuel cell in this invention. It is sectional drawing which shows the structure of the fuel cell of a prior art example.

Explanation of symbols

  1,101,1201 Electrolyte layer, 2,102a, 302a, 702a, 1202a Anode electrode, 3,102b, 302b, 702b, 1202b Cathode electrode, 4,106 Separator, 5 Extraction electrode, 6,59 Case, 7,109a 109b heater, 8, 107a anode fuel flow path, 9, 107b cathode fuel flow path, 15 substrate, 25, 35 metal layer, 45 oxide layer, 55 metal foil, 65, 75 current extraction unit, 16 thermistor, 26, 36 MOSET, 46 constant voltage, 56a, 56b resistance, 66 input terminal, 76 output terminal, 19 fuel container, 29 fuel supply port, 39 adhesive layer, 49 ventilation hole, 69a anode electrode wiring, 69b cathode electrode wiring, 91 temperature sensor, 92, 96, 98 control unit, 93 operation status monitor, 94 power storage device, 95 charge / discharge circuit, 97 monitor unit, 100, 200, 300, 700, 1200 fuel cell, 103, 104, 105 current collector, 108a, 108b, 1208a, 1208b diffusion layer, 300a, 300b, 300c cell 303a, 403a, 503a, 703a, 803a, 1003a, 1203a High resistance layer, 55, 303b, 403b, 503b, 703b, 803b, 1003b, 1203b Low resistance layer, 99, 311, 411a, 411b, 511, 711a, 711b , 811, 1011, 1211 Insulating layer, 312, 412, 512, 712 Insulating adhesive layer, 313, 413, 513, 713, 813, 1013 Insulating sealing part, 402, 502, 802, 1002 electrode, 414, 514, 814 , 1014 , 1214 Bonding member, 703c Medium resistance layer, 816, 1016 Adhesive layer, 441, 441a, 441b, 441c, 442, 442a, 442b, 442c, 443, 443a, 443b, 443c, 444, 444a, 444b, 444c, 445 445a, 445b, 445c, 446, 446a, 446b, 446c, 447a, 447b, 447c, 448a, 448b, 448c, 449c switch, 1300, 1400, 1500 Fuel cell system.

Claims (21)

Comprising at least an electrolyte layer, an anode electrode and a cathode electrode facing each other across the electrolyte layer, a current collector, and a separator;
The current collector comprises two or more layers including at least a high resistance layer forming one surface and a low resistance layer having a lower resistance value than the high resistance layer and forming the other surface. Having a laminated structure,
A fuel cell in which the current collector is in contact with the anode electrode and / or the cathode electrode directly or through a conductive member.   2. The fuel cell according to claim 1, wherein the fuel cell has a stacked structure in which the current collector on the anode side, the anode electrode, the electrolyte layer, the cathode electrode, and the current collector on the cathode side are stacked in this order.   2. The fuel cell according to claim 1, wherein the fuel cell has a laminated structure in which the anode electrode, the anode-side current collector, the electrolyte layer, the cathode-side current collector, and the cathode electrode are laminated in this order.   The fuel cell according to claim 1, wherein the low-resistance layer of the current collector is in contact with the anode electrode and / or the cathode electrode directly or through a conductive member.   5. The fuel cell according to claim 4, wherein layers other than the low resistance layer of the current collector are electrically connected to the anode electrode or the cathode electrode only through the low resistance layer. The two or more layers constituting the current collector are laminated via an insulating layer only in a region where the anode electrode or the cathode electrode is formed,
The fuel cell according to claim 5, wherein the fuel cell is electrically connected in at least a part of a region where the anode electrode or the cathode electrode is not formed.   The fuel cell according to claim 6, wherein each layer constituting the current collector has a takeout part for taking out a current. The current collector is formed between the electrolyte layer and the anode electrode and / or the cathode electrode,
The fuel cell according to claim 7, wherein layers other than the low resistance layer of the current collector are covered with an insulating layer in a region where the anode electrode and / or the cathode electrode is formed.   The fuel cell according to any one of claims 6 to 8, wherein the insulating layer is made of a porous body.   The fuel cell according to claim 8 or 9, wherein the current collector and the electrolyte layer are integrated by joining the insulating layer and the electrolyte layer.   The fuel cell according to claim 8, wherein the insulating layer is made of an electrolyte material.   The fuel cell according to claim 1, further comprising a heater. A fuel cell system for driving a load,
The fuel cell according to any one of claims 1 to 12,
A switch unit for controlling the presence or absence of energization to two or more layers constituting the current collector;
A temperature sensor for detecting at least one of a temperature of an anode electrode and / or a cathode electrode of the fuel cell and an outside air temperature;
A control unit for controlling the switch unit based on a detection result of the temperature sensor;
A fuel cell system comprising: A fuel cell system for driving a load,
The fuel cell according to any one of claims 1 to 12,
A switch unit for controlling the presence or absence of energization to two or more layers constituting the current collector;
A monitor for detecting the output current and / or output voltage of the fuel cell;
A control unit for controlling the switch unit based on the detection result of the monitor unit;
A fuel cell system comprising: The current collector is provided on the anode side and the cathode side of the fuel cell,
The current collectors on the anode side and the cathode side are each composed of a high resistance layer and a low resistance layer,
The switch part is
First and second switch elements for electrically connecting the load and the high resistance layer and the low resistance layer on the anode side, respectively;
Third and fourth switch elements for electrically connecting the load and the high resistance layer and the low resistance layer on the cathode side, respectively;
The fuel cell system according to claim 13 or 14, comprising:   The fuel cell system according to any one of claims 13 to 15, further comprising a power storage device and a charge / discharge circuit for the power storage device. A control method for a fuel cell system according to claim 13,
Detecting at least one of a temperature of an anode electrode and / or a cathode electrode of the fuel cell and an outside air temperature by the temperature sensor;
Based on the detection result, the step of controlling the switch unit by the control unit to energize layers other than the low resistance layer in the current collector;
With
A method for controlling a fuel cell system, wherein the temperature of an anode electrode and / or a cathode electrode is raised by passing a current through a layer other than the low resistance layer.   In the energizing step, based on the detection result, when the temperature of the anode electrode and / or the cathode electrode or the outside air temperature is lower than a predetermined temperature set in advance, a layer other than the low resistance layer in the current collector is provided. The fuel cell system control method according to claim 17, wherein energization is performed. In the detecting step, the temperature of the anode electrode and the cathode electrode is detected,
In the energizing step, when the temperature difference obtained by subtracting the temperature of the anode electrode from the temperature of the cathode electrode is lower than a predetermined value based on the detection result, a layer other than the low resistance layer in the current collector The method for controlling a fuel cell system according to claim 17, wherein power is supplied to the fuel cell system. A control method for a fuel cell system according to claim 14,
Detecting the output current and / or output voltage of the fuel cell by the monitor unit;
Based on the detection result, when the output current and / or the output voltage is lower than a predetermined value set in advance, the control unit controls the switch unit to energize layers other than the low resistance layer in the current collector And steps to
With
A method for controlling a fuel cell system, wherein the temperature of an anode electrode and / or a cathode electrode is raised by passing a current through a layer other than the low resistance layer. The current collector is provided on the anode side and the cathode side of the fuel cell,
The current collectors on the anode side and the cathode side are each composed of a high resistance layer and a low resistance layer,
The switch part is
First and second switch elements for electrically connecting the load and the high resistance layer and the low resistance layer on the anode side, respectively;
Third and fourth switch elements for electrically connecting the load and the high resistance layer and the low resistance layer on the cathode side, respectively;
Including
21. The method of controlling a fuel cell system according to claim 17, wherein energization of the high resistance layer in the energizing step is performed by conducting the first and third switch elements.

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