JP2011113912A - Fuel cell - Google Patents

Abstract

A fuel cell capable of stably outputting electric power while suppressing its size is provided.
A fuel cell according to one embodiment of the present invention includes a fuel cell main body that generates power by supplying fuel, a power storage element that is charged by electric power generated by the fuel cell main body, and heat generated during power generation of the fuel cell main body. In a state where is transmitted to the storage element, and a housing for storing the fuel cell body and the storage element.
[Selection] Figure 1

Description

  The present invention relates to a fuel cell including a storage element such as a secondary battery.

  In recent years, attempts have been made to use a fuel cell as a power source for portable electronic devices such as notebook computers and mobile phones so that they can be used for a long time without being charged. A fuel cell is characterized in that it can generate electric power simply by supplying fuel and air, and can generate electric power continuously for a long time if fuel is replenished. For this reason, if the fuel cell can be reduced in size, it can be said that the system is extremely advantageous as a power source for portable electronic devices.

  The direct methanol fuel cell (DMFC) is promising as a power source for portable electronic devices because it can be downsized and the fuel can be easily handled. As the liquid fuel supply method in the DMFC, there are known an active method such as a gas supply type and a liquid supply type, and a passive method such as an internal vaporization type in which the liquid fuel in the fuel container is vaporized inside the cell and supplied to the fuel electrode. It has been.

  Among these, a passive system such as an internal vaporization type is particularly advantageous for downsizing of the DMFC. In the passive DMFC, for example, a structure is proposed in which a membrane electrode assembly (fuel cell) having a fuel electrode, an electrolyte membrane, and an air electrode is disposed on a fuel containing portion made of a resin box-like container ( For example, see Patent Document 1).

  However, in the DMFC system, the temperature of the membrane electrode assembly rises due to the heat generated by the chemical reaction during power generation, and members constituting the membrane electrode assembly and members disposed around the membrane electrode assembly are However, there is a problem that the output of the fuel cell is lowered due to deterioration such as deformation and alteration due to heat. In order to prevent this, a method of detecting the temperature of the membrane electrode assembly and shutting off or suppressing the supply of fuel to the membrane electrode assembly when the detected temperature exceeds a preset value Alternatively, a method of providing a heat radiating member on the surface of the housing of the fuel cell and radiating the heat of the membrane electrode assembly to the outside can be considered.

International Publication No. 2005/112172 Pamphlet

However, when the supply of fuel is cut off or suppressed, the power generation reaction is suppressed, and as a result, the output of the fuel cell may be reduced. Further, when the heat of the membrane electrode assembly is radiated to the outside, it is necessary to increase the surface area of the heat radiating member to exchange heat with the outside in order to sufficiently radiate the heat generated in the membrane electrode assembly, and the fuel cell also becomes large. There is a fear.
The present invention has been made to solve such conventional problems, and an object thereof is to provide a fuel cell capable of stably outputting electric power while suppressing the size.

  A fuel cell according to one embodiment of the present invention includes a fuel cell main body that generates power by supplying fuel, a power storage element that is charged by power generated by the fuel cell main body, and heat generated during power generation of the fuel cell main body in the power storage element. And a housing for storing the fuel cell main body and the storage element in a transmitted state.

  ADVANTAGE OF THE INVENTION According to this invention, the fuel cell which can output electric power stably can be provided, suppressing a magnitude | size.

It is the figure which showed the structure of the fuel cell which concerns on 1st Embodiment. It is the figure which showed an example of the structure of the electric power generation cell of the fuel cell which concerns on 1st Embodiment. It is the figure which showed an example of the structure of the fuel distribution mechanism of the fuel cell which concerns on 1st Embodiment. It is the figure which showed an example of the arrangement | positioning relationship of the fuel cell main body and secondary battery of the fuel cell which concern on 1st Embodiment. It is the figure which showed an example of the arrangement | positioning relationship of the fuel cell main body and secondary battery of the fuel cell which concern on 1st Embodiment. It is the figure which showed the other example of the arrangement | positioning relationship of the fuel cell main body and secondary battery of the fuel cell which concern on 1st Embodiment. It is the figure which showed the other example of the arrangement | positioning relationship of the fuel cell main body and secondary battery of the fuel cell which concern on 1st Embodiment. It is the figure which showed an example of arrangement | positioning relationship of the fuel cell main body and secondary battery of the fuel cell which concern on other embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(First embodiment)
FIG. 1 is a diagram showing a configuration of a fuel cell 1 according to the first embodiment. The fuel cell 1 according to the first embodiment includes a valve 101, a pump 102, a fuel cell main body 103, a DC / DC converter 104 (step-up DC / DC converter), a fuel tank 105, a control unit 106, a lithium ion secondary battery. (LIB: Lithium-ion Battery) charging circuit 107, lithium ion secondary battery (hereinafter referred to as LIB; Lithium-ion Battery) 108, which is a storage element, DC / DC converter 109 (step-up DC / DC converter), output A terminal 110 and a housing 111 are provided. In the first embodiment, a direct methanol fuel cell (hereinafter referred to as DMFC) will be described as an example of the fuel cell 1.

  The fuel tank 105 stores liquid fuel used for power generation. Examples of the liquid fuel include methanol fuels such as aqueous methanol solutions of various concentrations and pure methanol. The liquid fuel is not necessarily limited to methanol fuel. The liquid fuel may be, for example, an ethanol fuel such as an ethanol aqueous solution or pure ethanol, a propanol fuel such as a propanol aqueous solution or pure propanol, a glycol fuel such as a glycol aqueous solution or pure glycol, dimethyl ether, formic acid, or other liquid fuel.

  The control unit 106 controls the entire fuel cell 1 according to the first embodiment. The control unit 106 controls the valve 101, the pump 102, the DC / DC converter 104, the LIB charging circuit 107, the DC / DC converter 109, and the like.

  The valve 101 opens and closes a fuel supply path from the fuel tank 105 to the fuel cell main body 103. The pump 102 supplies the fuel stored in the fuel tank 105 to the fuel cell main body 103. When fuel is supplied to the fuel cell main body 103, the fuel undergoes a chemical reaction with oxygen in the air to generate electricity.

  The electric power generated by the fuel cell main body 103 is boosted by the DC / DC converter 104. The electric power boosted by the DC / DC converter 104 is supplied to the LIB 108 by the LIB charging circuit 107. The LIB 108 is chargeable / dischargeable, temporarily stores electric power supplied from the fuel cell main body 103, and discharges it as necessary.

  The LIB 108 is a type of non-aqueous electrolyte secondary battery, and is a secondary battery in which lithium ions in the electrolyte are responsible for electrical conduction. The LIB 108 generally uses a lithium metal oxide for the positive electrode (anode) and a carbon material such as graphite for the negative electrode, and can be classified into the following types depending on the material of the positive electrode.

1. 1. Cobalt type lithium ion secondary battery 2. Nickel-based lithium ion secondary battery 3. Manganese lithium ion secondary battery Lithium ion secondary batteries using other lithium metal oxides such as iron and vanadium

Among the above, cobalt-based lithium ion secondary batteries are widely used, and lithium cobalt oxide is used for the positive electrode, a carbon material is used for the negative electrode, and a lithium salt dissolved in an organic solvent is used for the electrolytic solution. The chemical reaction formula at the time of charging is as follows. This chemical reaction is an endothermic reaction.
Positive electrode: LiCoO ₂ → Li _x CoO ₂ + (1-x) Li ⁺ + (1-x) e ⁻ (1)
Negative electrode: (1-x) Li ⁺ + (1-x) e ⁻ + C ₆ → Li _1-x C ₆ (2)
(X is a number such that 0 <x <1 and is usually about 0.5)

  The DC / DC converter 109 boosts the electric power supplied from the LIB 108 to a predetermined value and supplies it to an external load connected to the fuel cell 1 via the output terminal 110. That is, in the present embodiment, the electric power generated by the fuel cell main body 103 is once charged in the LIB 108 and then output to the external load connected to the fuel cell 1. The electric power charged in the LIB 108 is also used when supplying electric power necessary for operating the fuel cell 1 (for example, the valve 101 and the pump 102).

  2 and 3 are diagrams showing an example of the configuration of the fuel cell main body 103 of the fuel cell 1. Hereinafter, the configuration of the fuel cell main body 103 will be described with reference to FIGS.

  The fuel cell body 103 includes a membrane electrode assembly (MEA) 21 including an anode (fuel electrode) 22, a cathode (air electrode / oxidant electrode) 24, and an electrolyte membrane 23. The anode (fuel electrode) 22 has an anode catalyst layer 22a and an anode gas diffusion layer 22b. The cathode (air electrode / oxidant electrode) 24 includes a cathode catalyst layer 24b and a cathode gas diffusion layer 24a. The electrolyte membrane 23 is sandwiched between the anode catalyst layer 22a and the cathode catalyst layer 24b and has proton (hydrogen ion) conductivity.

  As the catalyst contained in the anode catalyst layer 22a and the cathode catalyst layer 24b, a simple substance of a platinum group element such as Pt, Ru, Rh, Ir, Os, Pd, an alloy containing the platinum group element, or the like can be used. For the anode catalyst layer 22a, it is preferable to use Pt—Ru, Pt—Mo or the like having strong resistance to methanol, carbon monoxide and the like. Pt, Pt—Ni, or the like is preferably used for the cathode catalyst layer 24b. However, the catalyst is not limited to these, and various substances having catalytic activity can be used. The catalyst may be a supported catalyst using a conductive support such as a carbon material or an unsupported catalyst.

  Examples of the proton conductive material constituting the electrolyte membrane 23 include fluorine-based resins such as perfluorosulfonic acid polymer having a sulfonic acid group (Nafion (trade name, manufactured by DuPont) and Flemion (trade name, manufactured by Asahi Glass Co., Ltd.). ), An organic material such as a hydrocarbon-based resin having a sulfonic acid group, or an inorganic material such as tungstic acid or phosphotungstic acid.

  The anode gas diffusion layer 22b is a current collector of the anode catalyst layer 22a that uniformly supplies fuel to the anode catalyst layer 22a. The cathode gas diffusion layer 24a is a current collector of the cathode catalyst layer 24b that uniformly supplies an oxidant to the cathode catalyst layer 24b. The anode gas diffusion layer 22b and the cathode gas diffusion layer 24a are made of a porous substrate.

  A conductive layer as a current collector is laminated on the anode gas diffusion layer 22b and the cathode gas diffusion layer 24a as necessary. As these conductive layers, for example, a porous layer (for example, mesh) made of a conductive metal material such as Au or Ni, a porous film, a foil body, a conductive metal material such as stainless steel (SUS), gold or the like. A composite material coated with a highly conductive metal can be used. Carbonaceous materials such as graphite (graphite) can also be used. A rubber 0-ring 26 is interposed between the electrolyte membrane 23 and a fuel distribution mechanism 31 and a cover plate 25, which will be described later. These 0-rings 26 prevent fuel leakage and oxidant leakage from the fuel cell main body 103.

  The cover plate 25 has an opening (not shown) for taking in air as an oxidizing agent. A moisture retaining layer and a surface layer are disposed between the cover plate 25 and the cathode 24 as necessary. The moisturizing layer is impregnated with a part of the water produced in the cathode catalyst layer 24b, and suppresses the transpiration of water and promotes the uniform diffusion of air into the cathode catalyst layer 24b. The surface layer adjusts the amount of air taken in, and has a plurality of air inlets whose number, size, etc. are adjusted according to the amount of air taken in. This moisture retention layer is comprised with the flat plate which consists of a polyethylene-made porous film etc., for example.

  A fuel distribution mechanism 31 is disposed on the anode (fuel electrode) 22 side of the fuel cell main body 103. A fuel tank 105 is connected to the fuel distribution mechanism 31 via a liquid fuel flow path 36 such as a pipe.

  Fuel is introduced into the fuel distribution mechanism 31 from the fuel tank 105 through the flow path 36. The flow path 36 is not limited to piping independent of the fuel distribution mechanism 31 and the fuel tank 105. For example, when the fuel distribution mechanism 31 and the fuel tank 105 are stacked and integrated, a fuel flow path connecting them may be used. The fuel distribution mechanism 31 may be connected to the fuel tank 105 via the flow path 36.

  As shown in FIG. 3, the fuel distribution mechanism 31 includes at least one fuel inlet 35 through which fuel flows through the flow path 36 and a plurality of fuel outlets 33 that discharge fuel and vaporized components thereof. A fuel distribution plate 32 is provided. The fuel distribution plate 32 is made of, for example, polyethylene terephthalate (PET) resin, polyethylene naphthalate (PEN) resin, polyimide resin, or the like. As shown in FIG. 2, a gap 34 serving as a fuel passage led from the fuel injection port 35 is provided inside the fuel distribution plate 32. The plurality of fuel discharge ports 33 are directly connected to the gaps 34 that function as fuel passages.

  The fuel introduced into the fuel distribution mechanism 31 from the fuel inlet 35 enters the gap 34 and is guided to the plurality of fuel outlets 33 through the gap 34 functioning as the fuel passage. For example, a gas-liquid separator (not shown) that transmits only the vaporized component of the fuel and does not transmit the liquid component may be disposed in the plurality of fuel discharge ports 33. This gas-liquid separator includes, for example, silicone rubber, low density polyethylene (LDPE) thin film, polyvinyl chloride (PVC) thin film, polyethylene terephthalate (PET) thin film, fluororesin (for example, polytetrafluoroethylene (PTFE), tetrafluoro An ethylene / perfluoroalkyl vinyl ether copolymer (PFA) or the like) and a microporous film. The gas-liquid separator may be installed as a gas-liquid separation membrane or the like between the fuel distribution mechanism 31 and the anode 22. The vaporized component of the fuel is discharged from a plurality of fuel discharge ports 33 toward a plurality of locations of the anode 22.

A plurality of fuel discharge ports 33 are provided on the surface of the fuel distribution plate 32 in contact with the anode 22. As a result, fuel can be supplied to the entire fuel cell main body 103. The number of the fuel discharge ports 33 may be two or more. However, in order to equalize the fuel supply amount in the surface of the fuel cell main body 103, the fuel discharge ports 33 of 0.1 to 10 / cm ² exist. It is preferable to form so as to.

  A pump 102 as a fuel transfer control unit is inserted into a flow path 36 that connects between the fuel distribution mechanism 31 and the fuel tank 105. The pump 102 is not a circulation pump that circulates fuel, but is a fuel supply pump that transfers fuel from the fuel tank 105 to the fuel distribution mechanism 31. By supplying fuel with such a pump 102 when necessary, the controllability of the fuel supply amount is improved.

  In this case, as the pump 102, a rotary vane pump, an electroosmotic pump, a diaphragm pump, a squeezing pump, etc. should be used from the viewpoint that a small amount of fuel can be sent with good controllability and can be reduced in size and weight. Is preferred. The fuel may be sent using gravity or a capillary phenomenon. When using gravity, the fuel tank 105 is disposed above the fuel cell main body 103. When the capillary phenomenon is used, the fuel flow path 36 is filled with a porous material.

  The rotary vane pump feeds liquid by rotating the wings with a motor. The electroosmotic flow pump uses a sintered porous material such as silica that causes an electroosmotic flow phenomenon. The diaphragm pump is a pump that feeds liquid by driving a diaphragm with an electromagnet or piezoelectric ceramics. The squeezing pump presses a part of the flexible fuel flow path and squeezes the fuel. Of the above pumps, it is more preferable to use an electroosmotic pump or a diaphragm pump having piezoelectric ceramics from the viewpoints of driving power and size. In addition, as long as the fuel is supplied from the fuel distribution mechanism 31 to the membrane electrode assembly 21, it is possible to use only the valve 101 without using the pump 102. In this case, the valve 101 is provided to control the supply of liquid fuel through the flow path 36.

  In such a configuration, the fuel stored in the fuel tank 105 is transferred through the flow path 36 by the pump 102 and supplied to the fuel distribution mechanism 31. The fuel discharged from the fuel distribution mechanism 31 is supplied to the anode (fuel electrode) 22 of the fuel cell main body 103. In the fuel cell main body 103, the fuel is diffused by the anode gas diffusion layer 22b and supplied to the anode catalyst layer 22a. When methanol fuel is used as the fuel, an internal reforming reaction of methanol shown in the following formula (3) occurs in the anode catalyst layer 22a.

  When pure methanol is used as the methanol fuel, the water generated in the cathode catalyst layer 24b and the water in the electrolyte membrane 23 are reacted with methanol to cause the internal reforming reaction of the following formula (l). Alternatively, the internal reforming reaction is caused by another reaction mechanism that does not require water.

_{CH 3 OH + H 2 O →} CO 2 tens ^{6H + + 6e - ... (3} )
Electrons (e ⁻ ) generated by this reaction are led to the outside via a current collector, supplied as so-called output to the load side, and then led to the cathode (air electrode) 24. In addition, protons (H ⁺ ) generated by the internal reforming reaction of the formula (3) are guided to the cathode 24 through the electrolyte membrane 23. Air is supplied to the cathode 24 as an oxidant. The electrons (e ⁻ ) and protons (H ⁺ ) that have reached the cathode 24 react with oxygen in the air in accordance with the following equation (4) in the cathode catalyst layer 24b, and water is generated along with this reaction.
6e ⁻ + 6H ⁺ + (3/2) O ₂ → 3H ₂ O (4)

  The fuel cell 1 shown in FIG. 2 is a type of fuel cell called a semi-passive. In the semi-passive type fuel cell, the fuel supplied from the fuel tank 105 to the membrane electrode assembly 21 is used for a power generation reaction and is not circulated thereafter and returned to the fuel tank 105. The semi-passive type fuel cell is different from the conventional active method because it does not circulate the fuel, and does not impair the downsizing of the device.

  Further, the fuel cell 1 uses a pump 102 for supplying fuel, and is different from a pure passive system such as a conventional internal vaporization type. For this reason, the fuel cell 1 is referred to as a semi-passive method as described above. Note that this semi-passive type fuel cell may be configured such that only the valve 101 is disposed instead of the pump 102 as long as fuel is supplied from the fuel tank 105 to the membrane electrode assembly 21. . In this case, the valve 101 is provided to control the supply of liquid fuel through the flow path 36.

  4A and 4B are diagrams illustrating an example of an arrangement relationship between the fuel cell main body 103 and the LIB 108 of the fuel cell 1 according to the first embodiment. FIG. 4A is a cross-sectional view of the fuel cell 1, and FIG. 4B is a plan view of the fuel cell 1. In FIG. 4A and FIG. 4B, illustration is abbreviate | omitted about structures other than the fuel cell main body 103 and LIB108.

  The fuel cell main body 103 and the LIB 108 are accommodated in a common casing 111. The casing 111 protects the fuel cell main body 103 and the LIB 108 and fixes the positional relationship between them, and the material and shape are not particularly limited.

  Each of the fuel cell main body 103 and the LIB 108 has at least one flat portion 103a, 108a, and is stored in the casing with the flat portion 103a of the fuel cell main body 103 and the flat portion 108a of the LIB 108 facing or in contact with each other. ing.

  In the example shown in FIGS. 4A and 4B, each of the fuel cell body 103 and the LIB 108 has a rectangular parallelepiped shape, and the inside of the casing 111 is in a state where the lower surface 103a of the fuel cell body 103 and the upper surface 108a of the LIB 108 face each other. It is stored in. The lower surface 103a of the fuel cell main body 103 and the upper surface 108a of the LIB 108 may be in contact with each other.

  In the example shown in FIGS. 4A and 4B, the heat generated in the fuel cell main body 103 is absorbed by the LIB 108, and it is necessary to cut off or suppress the supply of fuel or enlarge the heat dissipation member in order to suppress the temperature rise of the fuel cell main body 103. There is no. Further, the heat generated in the fuel cell main body 103 is absorbed by the LIB 108, and an increase in the temperature of the fuel cell main body 103 can be suppressed, so that power can be output stably.

  5A and 5B are diagrams showing another example of the arrangement relationship between the fuel cell main body 103 and the LIB 108 of the fuel cell 1 according to the first embodiment. FIG. 5A is a cross-sectional view of the fuel cell 1, and FIG. 5B is a plan view of the fuel cell 1. In FIGS. 5A and 5B, the components other than the fuel cell main body 103 and the LIB 108 are not shown.

  In the example shown in FIGS. 5A and 5B, the upper surface 103a of the fuel cell main body 103 and the upper surface 108a of the LIB 108 are arranged on substantially the same plane, and the upper surface 103a of the fuel cell main body 103 and the upper surface 108a of the LIB 108 are 112 is housed in the casing 111 in a state of facing the lower surface 112a of the 112. The upper surface 103a of the fuel cell main body 103 and the lower surface 112a of the heat conductor 112, and the upper surface 108a of the LIB 108 and the lower surface 112a of the heat conductor 112 may be in contact with each other.

  In the example shown in FIGS. 5A and 5B, the heat generated in the fuel cell main body 103 is absorbed by the LIB 108 through the heat conductor 112. For this reason, the heat generated in the fuel cell main body 103 is absorbed by the LIB 108, and it is not necessary to cut off or suppress the supply of fuel or increase the size of the heat dissipation member in order to suppress the temperature rise of the fuel cell main body 103. Further, the heat generated in the fuel cell main body 103 is absorbed by the LIB 108, and an increase in the temperature of the fuel cell main body 103 can be suppressed, so that power can be output stably. Furthermore, in the example shown in FIGS. 5A and 5B, the casing 111 of the fuel cell 1 can be thinned, and the design is improved.

  The thermal conductor 112 is a substance that does not dissolve, corrode, oxidize, etc. due to liquid fuel, water, oxygen, etc. and has a high thermal conductivity λ (the thermal conductivity at 20 ° C. is 10 W / mK or more. , Preferably 50 W / mK or more, more preferably 200 W / mK or more). This is because the heat exchange between the fuel cell main body 103 and the LIB 108 is more efficiently performed as the thermal conductivity λ increases.

  As the substance having a high thermal conductivity λ, metals such as stainless steel, copper, aluminum, tungsten, molybdenum, or alloys of these metals can be used. Carbonaceous materials such as graphite (graphite) can also be used. When a metal material is used as the heat conductor 112, it is necessary to prevent oxidation and corrosion by water generated at the cathode, oxygen, water vapor, etc. contained in the atmosphere. For this reason, the heat conductor 112 is made of a material that does not easily corrode such as stainless steel, or the surface is plated with a metal that is not easily oxidized, such as gold, or is coated with a carbonaceous material, resin, or rubber. Therefore, it is necessary to take measures such as painting with paint that does not dissolve in the liquid fuel vapor.

  As the resin or rubber for coating as described above, polyethylene, polypropylene, polystyrene, polyethylene terephthalate, nylon, polyetheretherketone (PEEK: trademark of Victorex), polytetrafluoroethylene (PTFE), tetrafluoroethylene -Resin such as perfluoroalkyl vinyl ether copolymer (PFA), polyvinyl chloride, polyimide, silicone resin, rubber such as ethylene / propylene rubber (EPDM), fluorine rubber, etc. can be used. Since these resins and rubbers have a lower thermal conductivity than metals, it is desirable to make the resin or rubber to be coated as thin as possible.

Next, specific examples of the fuel cell 1 according to the first embodiment and evaluation results thereof will be described.
(Configurations of Examples 1 and 2 and Comparative Example 1)
The configurations of Examples 1 and 2 and Comparative Example 1 will be described below.
In order not to give a detailed explanation, the configuration of the fuel cell main body 103 and the LIB 108, which is a feature of the present invention, is avoided to mention specific numerical values (the configuration of the fuel cell is not disclosed to other companies). For). → OK.

Example 1
In the first embodiment, the fuel cell main body 103 and the LIB 108 are arranged so as to have the positional relationship shown in FIGS. 4A and 4B. Hereinafter, the configuration of the fuel cell 1 according to the first embodiment will be described.
First, a perfluorocarbon sulfonic acid solution as a proton conductive resin and water and methoxypropanol as a dispersion medium are added to carbon black supporting anode catalyst particles, and carbon black supporting anode catalyst particles is dispersed and pasted. Was prepared. This paste was applied to porous carbon paper as the anode gas diffusion layer 22b to obtain an anode catalyst layer 22a.

  A paste is prepared by adding a perfluorocarbon sulfonic acid solution as a proton conductive resin and water and methoxypropanol as a dispersion medium to carbon black carrying cathode catalyst particles, and dispersing the carbon black carrying cathode catalyst particles. did. The paste was applied to porous carbon paper that is the cathode gas diffusion layer 24a to obtain a cathode catalyst layer 24b.

The anode gas diffusion layer 22b and the cathode gas diffusion layer 24a have the same shape and size and the same thickness, and the anode catalyst layer 22a and the cathode catalyst layer 24b applied to these gas diffusion layers have the same shape and size. is there.

  Between the anode catalyst layer 22a and the cathode catalyst layer 24b prepared as described above, a perfluorocarbon sulfonic acid membrane (trade name: nafion membrane, manufactured by DuPont) is used as the electrolyte membrane 23, and the anode catalyst layer 22a and the cathode catalyst layer 24b. The membrane electrode assembly was obtained by performing hot pressing in a state where the positions were aligned with each other.

  On the cathode gas diffusion layer 24a, a gold foil having an opening at a position corresponding to an air inlet of a cover plate 25 described later was laminated to form a cathode conductive layer. A gold foil having an opening at a position corresponding to the hole of the fuel distribution layer was laminated under the anode gas diffusion layer 22b to form an anode conductive layer. A polyethylene porous film was laminated on the cathode conductive layer as a moisture retention layer.

The air supplied from the outside air to the cathode will permeate the moisture retaining layer. A stainless plate (SUS304) having a plurality of rectangular air inlets formed on the moisture retaining layer was laminated as a cover plate 25. The fuel cell main body 103 finally obtained by the above procedure was a rectangular parallelepiped having a vertical length of about 64 mm, a horizontal length of about 44 mm, and a thickness of about 6 mm. The total surface area of the fuel cell body 103 is about 70.0 cm ² .

  The fuel cell main body 103 thus created is connected to the LIB 108 (aluminum laminate type lithium ion secondary battery having a capacity of 400 mAh) via the DC / DC converter 104, and a housing made of ABS resin having a thickness of 0.5 mm. It was stored in the body 111. The LIB 108 is a rectangular parallelepiped having a vertical length of about 38 mm, a horizontal length of about 30 mm, and a thickness of about 3.8 mm. Here, the bottom surface of the fuel cell main body 103 and the top surface of the LIB 108 are opposed to each other, and the distance therebetween is 4 mm.

At this time, of the total surface area of the fuel cell main body 103, the area where the distance to the upper surface of the LIB 108 is 5 mm or less is about 11.4 cm ² (about 16.3% of the total surface area of the fuel cell main body 103). Of the area projected vertically on the cathode catalyst layer 24b, the area overlapping the projection surface of the LIB 108 from the same direction is about 10.0 cm ² (51.9% of the projected area of the cathode catalyst layer 24b).

(Example 2)
In Example 2, the fuel cell main body 103 and the LIB 108 are arranged so as to have the positional relationship shown in FIGS. 5A and 5B. The configuration of the fuel cell main body 103 is the same as that of the first embodiment.
Hereinafter, the configuration of the fuel cell 1 according to Example 2 will be described.

  In the second embodiment, one of the short sides (about 44 mm in length) of the fuel cell main body 103 faces the short side (about 30 mm in length) of the LIB 108 with a distance of 4 mm, and the fuel cell main body 103 The flat surface formed by the cathode catalyst layer 24b and the surface having the largest area among the external shapes of the LIB 108 were arranged in parallel.

  Further, an aluminum plate (thermal conductivity 204 W / mK at 20 ° C.) having a vertical length of 100 mm, a horizontal length of 56 mm, and a thickness of 0.5 mm is used as the heat conductor 112 as a cover plate of the fuel cell main body 103. It arrange | positioned so that the distance with 25 might be set to 0.5 mm. The heat conductor 112 (aluminum plate) is provided with a hole having the same shape and the same size as the air inlet provided in the cover plate 25 of the fuel cell main body 103. Further, the LIB 108 was disposed so that the distance from the thermal conductor 112 was 0.5 mm. It should be noted that the surface having the largest area of the outer shape of the LIB 108 is disposed so as to face the heat conductor 112.

Of the total surface area of the fuel cell body 103, the area where the distance to the closest surface of the heat conductor 112 is 2 mm or less is about 28.7 cm ² (about 41% of the total surface area of the fuel cell body 103). Further, all of the area projected vertically of the cathode catalyst layer 24b (100% of the projected area of the cathode catalyst layer 24b) overlaps the projection surface of the heat conductor 112 from the same direction.

(Comparative Example 1)
In this comparative example 1, the fuel cell main body 103 and the LIB 108 are arranged so as to have the positional relationship shown in FIGS. 5A and 5B as in the second embodiment, but the heat conductor 112 is not provided. Different from 2. The configuration of the fuel cell main body 103 is the same as that of the first embodiment.
Hereinafter, the configuration of the fuel cell 1 according to Comparative Example 1 will be described.

Of the total surface area of the fuel cell main body 103, the area where the distance to the surface closest to the LIB 108 is 5 mm or less is about 2.6 cm ² (about 3.7% of the total surface area of the fuel cell main body 103). In addition, among the areas obtained by vertically projecting the cathode catalyst layer 24b, the area overlapping the projection surface of the LIB 108 from the same direction is zero.

(Comparison between Examples 1 and 2 and Comparative Example 1)
Next, in order to start up the fuel cell 1 obtained in Conventional Example 1, Examples 1 and 2 and Comparative Example 1 in this way and charge the voltage of the lithium ion secondary battery from 3.0 V to 4.0 V The time (minutes) required was measured.

  The measurement was performed in an environment where the temperature was 25 ° C. and the relative humidity was 50%. In addition, a thermocouple is attached to the surface of the center portion of the surface cover, and the supply amount of pure methanol (purity 99.9 wt%) is controlled so that the temperature measured by this thermocouple is constant at 45 ° C. . Further, the DC / DC converter 104 controls the current so that the output voltage of the fuel cell main body 103 (the input voltage of the DC / DC converter 104) is constant at 1.4V, and the voltage of the LIB 108 is increased from 3.0V. The battery was charged until it reached 4.0V.

Table 1 shows the time (minutes) required for charging under the above conditions.

  As shown in Table 1, the time required for charging by the fuel cells 1 according to Examples 1 and 2 and Comparative Example 1 is 240 minutes, 230 minutes, and 280 minutes, respectively. As is clear from this, in the fuel cell 1 according to Examples 1 and 2, the time required for charging the LIB 108 is shorter than that of the fuel cell 1 according to Comparative Example 1. From this, it can be inferred that in the fuel cells 1 of Examples 1 and 2, the output of the fuel cell 1 (power generated per unit time) is higher than that in Comparative Example 1.

  This is because at least a part of the heat generated by the power generation of the fuel cell 1 is absorbed by an endothermic reaction when the LIB 108 is charged, and the temperature of the fuel cell 1 does not rise excessively. This is considered to be due to the smooth progress of the reaction represented by 3) or formula (4).

(Other embodiments)
Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. For example, as shown in FIG. 6, the fuel cell main body 103, the heat conductor 112, and the LIB 108 may be housed in the casing 111 in a state of being stacked in the same order. In this case, since the heat generated in the fuel cell main body 103 is absorbed by the LIB 108 via the heat conductor 112 having high thermal conductivity, it can be expected that the endothermic effect by the LIB 108 is further increased. The fuel cell main body 103 and the heat conductor 112, and the LIB 108 and the heat conductor 112 may be stacked in contact with each other, or a space may be provided between them or may be stacked.

  In the first embodiment, the lithium ion secondary battery (LIB 108), which is a secondary battery, has been described as an example of the special electric element. However, as long as it has an endothermic reaction during charging, other types of power storage elements Can also be used.

  DESCRIPTION OF SYMBOLS 1 ... Fuel cell, 101 ... Valve, 102 ... Pump, 103 ... Fuel cell main body, 104 ... DC / DC converter, 105 ... Fuel tank, 106 ... Control part, 107 ... LIB charging circuit, 108 ... LIB (electric storage element), DESCRIPTION OF SYMBOLS 109 ... DC / DC converter, 110 ... Output terminal, 111 ... Housing, 112 ... Thermal conductor, 22 ... Anode, 23 ... Electrolyte membrane, 24 ... Cathode, 25 ... Cover plate, 26 ... O-ring, 31 ... Fuel distribution mechanism 32 ... Fuel distribution plate, 33 ... Fuel discharge port, 34 ... Gap, 35 ... Fuel injection port, 36 ... Flow path.

Claims (6)

A fuel cell body that generates electricity by supplying fuel; and
A storage element charged by the power generated by the fuel cell body; and
In a state where heat generated during power generation of the fuel cell main body is transmitted to the power storage element, a housing that houses the fuel cell main body and the power storage element;
A fuel cell comprising:   The fuel cell according to claim 1, further comprising a heat conductor that transfers heat generated in the fuel cell main body to the power storage element.   Each of the fuel cell main body and the power storage element has at least one flat portion, and at least one flat portion of the fuel cell main body and at least one flat portion of the power storage element face or contact each other. The fuel cell according to claim 1 or 2, wherein the fuel cell is housed in the housing.   Each of the fuel cell main body and the electricity storage element has a rectangular parallelepiped shape, and the lower surface of the fuel cell main body and the upper surface of the electricity storage element constituting the rectangular parallelepiped shape are accommodated in the casing so as to face or contact each other. The fuel cell according to claim 1 or 2, wherein   The fuel cell main body and the power storage element have a distance of 5 mm or less between the fuel cell main body and the power storage element, and the area of the fuel cell main body facing or contacting the power storage element is the entire area of the fuel cell main body. The fuel cell according to any one of claims 1 to 4, wherein the fuel cell is housed in the casing so as to have a surface area of 15% or more.   The fuel cell according to any one of claims 1 to 5, wherein the power storage element is a lithium ion secondary battery.

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