JP2009295542A - Fuel battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel battery capable of increasing an amount of water supplied to an anode (a fuel electrode) and suppressing the deterioration of the diffusion of an oxidizing gas on a cathode catalyst layer and obtaining a high output. <P>SOLUTION: The fuel battery 1 comprises an anode (a fuel electrode) 13, a cathode (an air electrode) 16, a fuel battery cell 10 having an electrolyte membrane 17 sandwiched by the anode and the cathode, a moisturizing layer 50 arranged by being laminated on the cathode (air electrode) 16, and a surface cover 60 arranged by being laminated on the moisturizing layer 50 and having an air inlet 61. The cathode catalyst layer 14 of the cathode (air electrode) 16 has a first catalyst layer 14a located so as to correspond to the air inlet 61 of the surface cover 60, and a second catalyst layer 14b forming a section excluding the first catalyst layer 14a. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fuel cell using liquid fuel.

  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. The fuel cell has a feature 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 becomes a very advantageous system 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 miniaturized 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.

  Various methods can be adopted as means for supplying fuel to the anode (fuel electrode). Examples of the fuel supply means include a system in which a liquid fuel such as an aqueous methanol solution is directly circulated under the anode conductive layer. Furthermore, an external vaporization type in which methanol or the like is evaporated outside the fuel cell to produce a gaseous fuel, and the gaseous fuel flows under the anode conductive layer, or a liquid fuel such as pure methanol or an aqueous methanol solution in the fuel storage part And a fuel supply means such as an internal vaporization type that vaporizes the liquid fuel inside the cell and supplies it to the anode.

  On the other hand, as means for supplying air as an oxidant to the cathode (air electrode), an active type that forcibly supplies air with a fan or a blower, or a spontaneous breathing (passive) type that supplies air only by natural diffusion from the atmosphere Etc.

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

  Here, the membrane electrode assembly includes an anode (fuel electrode) having an anode catalyst layer and an anode gas diffusion layer, a cathode (air electrode) having a cathode catalyst layer and a cathode gas diffusion layer, an anode catalyst layer, and a cathode. An electrolyte membrane having proton (hydrogen ion) conductivity sandwiched between catalyst layers. The membrane electrode assembly is sandwiched between an anode conductive layer disposed on the anode (fuel electrode) side and a cathode conductive layer disposed on the cathode (air electrode) side.

The liquid fuel supplied to the fuel supply unit from the fuel storage unit via the flow path remains as the liquid fuel or the fuel distribution layer and the anode conductive layer are formed in a state where the liquid fuel and the vaporized fuel in which the liquid fuel is vaporized are mixed. To the anode gas diffusion layer of the fuel cell. The fuel supplied to the anode gas diffusion layer is diffused in the anode gas diffusion layer and supplied to the anode catalyst layer. When methanol fuel is used as the liquid fuel, an internal reforming reaction of methanol represented by the following formula (1) occurs in the anode catalyst layer.
CH ₃ OH + H ₂ O → CO ₂ + 6H ⁺ + 6e ⁻ Formula (1)

  When pure methanol is used as the methanol fuel, the methanol is reformed by the internal reforming reaction of the above formula (1) with water generated in the cathode catalyst layer or water in the electrolyte membrane, or It is modified by other reaction mechanisms that do not require water.

Electrons (e ⁻ ) generated by this reaction are guided to the outside via a current collector, and are operated to a cathode (air electrode) after operating a portable electronic device or the like as so-called electricity. The proton (H ⁺ ) generated by the internal reforming reaction of the above formula (1) is guided to the cathode through the electrolyte membrane. Air is supplied to the cathode (air electrode) as an oxidant gas through the moisture retaining layer. Electrons (e ⁻ ) and protons (H ⁺ ) that have reached the cathode (air electrode) cause a reaction shown in the following formula (2) with oxygen in the air in the cathode catalyst layer, and water is generated along with this power generation reaction. Generate.
(3/2) O ₂ + 6e ⁻ + 6H ⁺ → 3H ₂ O Formula (2)

In order for the internal reforming reaction described above to be performed smoothly and to obtain a high output and a stable output in the fuel cell, at least a part of the water (H ₂ O) generated in the cathode catalyst layer by Formula (2) is used. The cycle that permeates the electrolyte membrane, diffuses into the anode catalyst layer, and is consumed by the reaction of the above formula (1) needs to be performed smoothly.

  To achieve this, a moisturizing layer that impregnates water generated in the cathode catalyst layer to suppress transpiration is placed near the cathode (air electrode), and the moisture retention amount of the cathode catalyst layer is the moisture retention of the anode catalyst layer. A state in which the amount is larger than the amount is configured, and water generated in the cathode catalyst layer using the osmotic pressure phenomenon is supplied to the anode catalyst layer through the electrolyte membrane.

In the fuel cell that supplies water from the cathode (air electrode) to the anode (fuel electrode) as described above, the amount of water supplied to the anode (fuel electrode) is increased to promote the reaction of the above formula (1). In order to improve the output, the amount of proton conductive resin in the cathode catalyst layer is increased to increase the hydrophilicity of the cathode catalyst layer, or the porosity of the cathode catalyst layer is decreased to generate in the cathode catalyst layer. The method which suppresses that the water which carried out evaporates to external air as water vapor | steam is taken (for example, refer patent document 2-3).
International Publication No. 2005/112172 Pamphlet JP 2007-80725 A JP 2007-80726 A

  However, as in the conventional fuel cell described above, the amount of proton conductive resin in the cathode catalyst layer is increased to increase the hydrophilicity of the cathode catalyst layer, or the porosity of the cathode catalyst layer is decreased to reduce the cathode catalyst layer. In the configuration in which the water generated in the layer is prevented from evaporating to the outside air as water vapor, the pores of the cathode catalyst layer are blocked by the generated water, and the air diffusibility in the cathode catalyst layer may be reduced. This makes it difficult for the reaction of the above-described formula (2) to occur, and there is a problem that the output of the fuel cell decreases. On the other hand, in order to improve the air diffusibility in the cathode catalyst layer, if the amount of proton conductive resin in the cathode catalyst layer is reduced or the porosity of the cathode catalyst layer is increased, it is supplied to the anode (fuel electrode). The amount of water decreased, resulting in a decrease in fuel cell output.

  Accordingly, the present invention has been made to solve the above-described problems, and can increase the amount of water supplied to the anode (fuel electrode) and suppress a decrease in the diffusion of oxidizing gas in the cathode catalyst layer. An object of the present invention is to provide a fuel cell capable of obtaining a high output.

  According to one aspect of the present invention, a membrane electrode assembly having a fuel electrode, an air electrode, and an electrolyte membrane sandwiched between the fuel electrode and the air electrode is disposed in a stacked manner on the air electrode. A fuel cell comprising a moisturizing layer and a surface cover having an air inlet arranged to be laminated on the moisturizing layer, wherein the cathode catalyst layer of the air electrode corresponds to the air inlet of the surface cover. A fuel cell is provided, comprising: a first catalyst layer positioned at a distance between the first catalyst layer and a second catalyst layer constituting a portion other than the first catalyst layer.

  According to the fuel cell of the present invention, it is possible to increase the amount of water supplied to the anode (fuel electrode) and to suppress a reduction in the diffusion of the oxidizing gas in the cathode catalyst layer, thereby obtaining a high output.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a cross-sectional view showing a configuration of a fuel cell 1 according to an embodiment of the present invention. FIG. 2 is a plan view of the cathode catalyst layer 14. FIG. 3 is a cross-sectional view showing a configuration when the fuel cell 1 according to the first embodiment of the present invention includes the pump 70.

  As shown in FIG. 1, the fuel cell 1 includes a fuel cell 10 constituting an electromotive unit, and anode conductivity provided on the anode (fuel electrode) side and the cathode (air electrode) side of the fuel cell 10. A layer 18, a cathode conductive layer 19, a fuel distribution layer 30 having a plurality of openings 31 provided to face the anode conductive layer 18, and a side of the fuel distribution layer 30 different from the fuel cell 10 side. A fuel supply mechanism 40 that is disposed and supplies liquid fuel F to the fuel distribution layer 30, a moisturizing layer 50 laminated on the cathode conductive layer 19, and a plurality of air inlets 61 laminated on the moisturizing layer 50. A front cover 60.

  The fuel cell 10 is a so-called membrane electrode assembly (MEA), and includes an anode (fuel electrode) 13 having an anode catalyst layer 11 and an anode gas diffusion layer 12, a cathode catalyst layer 14, and a cathode gas diffusion. A cathode (air electrode) 16 having a layer 15 and an electrolyte membrane 17 having proton (hydrogen ion) conductivity sandwiched between the anode catalyst layer 11 and the cathode catalyst layer 14.

  Examples of the catalyst contained in the anode catalyst layer 11 include a simple substance of a platinum group element such as Pt, Ru, Rh, Ir, Os, and Pd, and an alloy containing the platinum group element. Specifically, it is preferable to use, for example, Pt—Ru, Pt—Mo or the like having strong resistance to methanol, carbon monoxide, or the like as the anode catalyst layer 11. However, the catalyst is not limited to these, and various substances having catalytic activity can be used. The catalyst may be either a supported catalyst using a conductive support such as a carbon material or an unsupported catalyst. The anode catalyst layer 11 and the cathode catalyst layer 14 contain a proton conductive electrolyte.

  As shown in FIGS. 1 and 2, the cathode catalyst layer 14 constitutes a first catalyst layer 14 a located corresponding to the air inlet 61 of the surface cover 60 and a portion other than the first catalyst layer 14 a. And the second catalyst layer 14b.

  Here, the 1st catalyst layer 14a is comprised so that the ratio of the proton conductive resin contained in a catalyst layer may become lower than the 2nd catalyst layer 14b. In this way, by configuring the first catalyst layer 14a such that the proportion of the proton conductive resin contained in the catalyst layer is lower than that of the second catalyst layer 14b, in the first catalyst layer 14a, It is possible to improve the diffusibility of air. Further, the second catalyst layer 14b can suppress the water generated in the cathode catalyst layer 14 from being evaporated to the outside as water vapor. The first catalyst layer 14a is configured to have a higher porosity than the second catalyst layer 14b. In this way, by configuring the first catalyst layer 14a to have a higher porosity than the second catalyst layer 14b, it is possible to improve air diffusibility in the first catalyst layer 14a. it can. Further, the second catalyst layer 14b can suppress the water generated in the cathode catalyst layer 14 from being evaporated to the outside as water vapor. Note that the first catalyst layer 14a may be configured so that the proportion of the proton conductive resin contained in the catalyst layer is lower and the porosity is higher than that of the second catalyst layer 14b.

  Examples of the catalyst contained in the cathode catalyst layer 14 include a simple substance of a platinum group element such as Pt, Ru, Rh, Ir, Os, and Pd, an alloy containing the platinum group element, and the like. Specifically, for example, Pt, Pt—Ni, Pt—Co or the like is preferably used as the cathode catalyst layer 14. However, the catalyst is not limited to these, and various substances having catalytic activity can be used. The catalyst may be either a supported catalyst using a conductive support such as a carbon material or an unsupported catalyst.

  (1) In the cathode catalyst layer 14, the total area of the first catalyst layer 14 a, that is, the total area of the first catalyst layer 14 a on the surface of the cathode catalyst layer 14 is the air inlet 61 of the surface cover 60. And (2) the first catalyst layer 14a located corresponding to the air inlet 61 of the surface cover 60, as viewed in the thickness direction of the fuel cell 1. In some cases, the total area of the portions where the air inlet 61 and the first catalyst layer 14 a overlap is preferably configured to be 0.3 times or more the total area of the air inlet 61. In other words, when the surface cover 60 is orthogonally projected onto the surface of the cathode catalyst layer 14, the total area of the portions where the air introduction port 61 and the first catalyst layer 14 a overlap is the air introduction port 61. It is preferable that the total area be 0.3 times or more of the total area.

  Here, it is preferable to set this range when the total area of the first catalyst layer 14a is smaller than 0.5 times the total area of the air inlets 61 of the surface cover 60. This is because the effect of improving the air diffusibility by the catalyst layer 14a cannot be sufficiently obtained, and when the ratio is larger than 1.5 times, the effect of suppressing the evaporation of water vapor to the outside air by the second catalyst layer 14b is sufficiently obtained. This is because the total area of the portion where the air inlet 61 and the first catalyst layer 14a overlap is smaller than 0.3 times the total area of the air inlet 61. This is because neither of the above two effects can be obtained. Note that the upper limit of the range in (2) is 1 time, and this is 1 time when the first catalyst layer 14 a is configured to overlap the air inlet 61.

  Examples of the proton conductive material constituting the electrolyte membrane 17 include fluorine-based resins (Nafion (trade name, manufactured by DuPont) and Flemion (trade name, manufactured by Asahi Glass Co., Ltd.) such as a perfluorosulfonic acid polymer having a sulfonic acid group. Etc.), organic materials such as hydrocarbon resins having sulfonic acid groups, or inorganic materials such as tungstic acid and phosphotungstic acid. However, the proton conductive electrolyte membrane 17 is not limited to these.

  The anode gas diffusion layer 12 laminated on the anode catalyst layer 11 serves to uniformly supply fuel to the anode catalyst layer 11 and also serves as a current collector for the anode catalyst layer 11. The cathode gas diffusion layer 15 laminated on the cathode catalyst layer 14 serves to uniformly supply the oxidant to the cathode catalyst layer 14 and also serves as a current collector for the cathode catalyst layer 14. The anode gas diffusion layer 12 and the cathode gas diffusion layer 15 are porous bodies or meshes made of a porous carbonaceous material such as carbon paper, carbon cloth, or carbon silk, or a metal material such as titanium, titanium alloy, stainless steel, or gold. Etc.

  The anode conductive layer 18 laminated on the surface of the anode gas diffusion layer 12 and the cathode conductive layer 19 laminated on the surface of the cathode gas diffusion layer 15 are, for example, a mesh or a porous film made of a conductive metal material such as Au. Etc. Among these, the anode conductive layer 18 and the cathode conductive layer 19 are preferably formed of a thin film having a plurality of openings opened corresponding to the fuel cell 10, and the fuel cell is formed through the openings. The fuel from the opening 31 of the fuel distribution layer 30 provided facing the cell 10 is guided to the fuel cell 10. The anode conductive layer 18 and the cathode conductive layer 19 are configured so that fuel and oxidant do not leak from their peripheral edges. Also, rubber O-rings 20 are interposed between the electrolyte membrane 17 and the anode conductive layer 18 and the cathode conductive layer 19, respectively, thereby preventing fuel leakage and oxidant leakage from the fuel cell 10. is doing. Here, although the fuel cell 1 including the anode conductive layer 18 and the cathode conductive layer 19 is shown, the anode gas diffusion layer 12 and the anode conductive layer 18 and the cathode conductive layer 19 are not provided as described above. The cathode gas diffusion layer 15 may function as a diffusion layer and may function as a conductive layer.

  The moisturizing layer 50 is impregnated with a part of the water generated in the cathode catalyst layer 14 to suppress the transpiration of water and promote uniform diffusion of air to the cathode catalyst layer 14. The moisturizing layer 50 is composed of a flat plate made of, for example, a polyethylene porous film.

  The front cover 60 adjusts the amount of air taken in, and the adjustment is performed by changing the number and size of the air inlets 61. The front cover 60 is preferably made of, for example, a stainless alloy such as SUS304 or SUS316L, or a metal such as titanium or a titanium alloy.

  The fuel supply mechanism 40 mainly includes a fuel storage part 41, a fuel supply part main body 42, and a flow path 44.

  The fuel storage unit 41 stores liquid fuel F corresponding to the fuel battery cell 10. The fuel storage portion 41 is made of a material that does not cause dissolution or alteration by the liquid fuel F. Specifically, polyethylene (PE), polypropylene (PP), polyetheretherketone (PEEK), or the like is used as a material constituting the fuel storage unit 41. Although not shown, the fuel storage portion 41 is provided with a fuel supply port for supplying the liquid fuel F.

  Examples of the liquid fuel F include methanol fuels such as methanol aqueous solutions having various concentrations and pure methanol. The liquid fuel F is not necessarily limited to methanol fuel. The liquid fuel F may be, for example, an ethanol fuel such as an ethanol aqueous solution or pure ethanol, a propanol fuel such as a propanol aqueous solution or pure propanol, a glycol fuel such as a glycol aqueous solution or pure glycol, dimethyl ether, formic acid, or other liquid fuel. In any case, liquid fuel corresponding to the fuel cell 10 is stored in the fuel storage portion 41.

  The fuel supply unit main body 42 includes a fuel supply unit 43 including recesses for uniformly dispersing the liquid fuel F in order to uniformly supply the supplied liquid fuel F to the fuel distribution layer 30. The fuel supply unit 43 is connected to the fuel storage unit 41 via a flow path 44 of the liquid fuel F configured by piping or the like.

  The liquid fuel F stored in the fuel storage part 41 can be dropped and sent to the fuel supply part 43 via the flow path 44 using gravity. Alternatively, the flow path 44 may be filled with a porous body or the like, and the liquid fuel F stored in the fuel storage unit 41 may be fed to the fuel supply unit 43 by capillary action. Further, as shown in FIG. 3, the liquid fuel F stored in the fuel storage unit 41 may be forcibly sent to the fuel supply unit 43 by interposing a pump 70 in a part of the flow path 44.

  The pump 70 functions as a supply pump that simply supplies the liquid fuel F from the fuel storage unit 41 to the fuel supply unit 43, and is a circulation pump that circulates excess liquid fuel F supplied to the fuel cells 10. It does not have the function as. Since the fuel cell 1 provided with the pump 70 does not circulate fuel, the fuel cell 1 is called a so-called semi-passive type, which has a different configuration from a conventional active method and a different configuration from a pure passive method such as a conventional internal vaporization type. Applicable to the method. The type of the pump 70 that functions as the fuel supply means is not particularly limited, but from the viewpoint that a small amount of the liquid fuel F can be fed with good controllability and that further reduction in size and weight can be achieved. It is preferable to use a vane pump, an electroosmotic flow pump, a diaphragm pump, a squeezing pump, or the like. The rotary vane pump feeds liquid by rotating wings with a motor. The electroosmotic flow pump uses a sintered porous body such as silica that causes an electroosmotic flow phenomenon. A diaphragm pump drives a diaphragm with an electromagnet or piezoelectric ceramics to send liquid. The squeezing pump presses a part of a flexible fuel flow path and squeezes the fuel. Among these, it is more preferable to use an electroosmotic pump or a diaphragm pump having piezoelectric ceramics from the viewpoint of driving power, size, and the like. When the pump 70 is provided as described above, the pump 70 is electrically connected to control means (not shown), and the supply amount of the liquid fuel F supplied to the fuel supply unit 43 is controlled by the control means. .

  The fuel distribution layer 30 is configured by, for example, a flat plate in which a plurality of openings 31 are formed, and is sandwiched between the anode gas diffusion layer 12 and the fuel supply unit 43. The fuel distribution layer 30 is made of a material that does not allow the vaporized component of the liquid fuel F or the liquid fuel F to permeate. Specifically, for example, a polyethylene terephthalate (PET) resin, a polyethylene naphthalate (PEN) resin, or a polyimide resin. Etc. Further, the fuel distribution layer 30 may be constituted by, for example, a gas-liquid separation membrane that separates the vaporized component of the liquid fuel F and the liquid fuel F and permeates the vaporized component to the fuel cell unit 10 side. Examples of the gas-liquid separation membrane include silicone rubber, low density polyethylene (LDPE) thin film, polyvinyl chloride (PVC) thin film, polyethylene terephthalate (PET) thin film, fluororesin (for example, polytetrafluoroethylene (PTFE), tetrafluoroethylene). -Perfluoroalkyl vinyl ether copolymer (PFA) etc.) A microporous film etc. are used.

  Next, a method for forming the cathode catalyst layer 14 composed of the first catalyst layer 14a and the second catalyst layer 14b will be described. Here, five methods (a) to (e) are illustrated as methods for forming the cathode catalyst layer 14, but are not limited to these forming methods.

  (A) First, two cathode gas diffusion layers (a first cathode gas diffusion layer and a second cathode gas diffusion layer) are prepared. The two cathode gas diffusion layers may have the same thickness and properties. A catalyst paste having the composition of the first catalyst layer 14a is applied to the entire surface of the first cathode gas diffusion layer and dried to form the first catalyst layer 14a. A catalyst paste having the composition of the second catalyst layer 14b is applied to the entire surface of the second cathode gas diffusion layer and dried to form the second catalyst layer 14b.

  After that, the second cathode gas diffusion layer on which the second catalyst layer 14b is formed has a through-hole formed at a position corresponding to the air inlet 61 of the surface cover 60, that is, at the same position as the air inlet 61 of the surface cover 60. To do. On the other hand, the first cathode gas diffusion layer on which the first catalyst layer 14 a is formed is cut into the same shape as the air inlet 61 of the surface cover 60. Then, what was cut out from the first cathode gas diffusion layer is fitted into the through hole formed in the second cathode gas diffusion layer. By such a method, the cathode catalyst layer 14 composed of the first catalyst layer 14a and the second catalyst layer 14b can be formed.

  (B) First, a first mask cut out in a shape for applying the first catalyst layer 14a is disposed on the substrate constituting the cathode gas diffusion layer, and a catalyst paste having the composition of the first catalyst layer 14a is disposed. Apply. After the paste is dried, the first mask is removed. Thus, the first catalyst layer 14a is formed at a predetermined position on the substrate.

  Subsequently, on the substrate on which the first catalyst layer 14a is formed, a second mask cut out in a shape for applying the second catalyst layer 14b is disposed, and a catalyst paste having the composition of the second catalyst layer 14b Apply. After the paste is dried, the second mask is removed. By such a method, the cathode catalyst layer 14 composed of the first catalyst layer 14a and the second catalyst layer 14b can be formed. The order in which the first catalyst layer 14a and the second catalyst layer 14b are formed is not particularly limited, and the second catalyst layer 14b may be formed first.

  (C) The catalyst layer is formed by directly spraying the catalyst paste for forming the first catalyst layer 14a and the second catalyst layer 14b on the substrate constituting the cathode gas diffusion layer as in an air spray or an ink jet printer. Using a coating device, the catalyst paste for forming the first catalyst layer 14a and the second catalyst layer 14b is respectively applied to predetermined positions. Then, the applied catalyst paste is dried. By such a method, the cathode catalyst layer 14 composed of the first catalyst layer 14a and the second catalyst layer 14b can be formed.

  (D) First, a catalyst paste having the composition of the first catalyst layer 14a is applied to the entire surface of the substrate constituting the cathode gas diffusion layer and dried to form the first catalyst layer 14a. On this first catalyst layer 14a, a mask cut out in a shape for applying the second catalyst layer 14b is disposed, and a solution in which only the proton conductive resin is dispersed is applied. When the mask is removed after the solution is dried, the portion where the solution in which only the proton conductive resin is dispersed is applied becomes the second catalyst layer 14b, and the portion where the solution is not applied becomes the first catalyst layer 14a. . By such a method, the cathode catalyst layer 14 composed of the first catalyst layer 14a and the second catalyst layer 14b can be formed.

  (E) First, a catalyst paste having the composition of the first catalyst layer 14a is applied to the entire surface of the substrate constituting the cathode gas diffusion layer and dried to form the first catalyst layer 14a. On the first catalyst layer 14a, a hard plate cut out in the same shape as the portion forming the second catalyst layer 14b is disposed, and the cathode catalyst layer is compressed by a press, a vise or a heavy stone. Subsequently, when the hard plate is removed, the portion compressed by the hard plate becomes the second catalyst layer 14b, and the portion not compressed becomes the first catalyst layer 14a. By such a method, the cathode catalyst layer 14 composed of the first catalyst layer 14a and the second catalyst layer 14b can be formed.

  Next, the operation of the fuel cell 1 described above will be described.

The liquid fuel F led out from the fuel storage unit 41 toward the fuel supply unit 43 via the flow path 44 is supplied to the fuel supply unit 43 and remains as the liquid fuel F, or the liquid fuel F and the liquid fuel F are vaporized. The vaporized fuel is mixed and supplied to the anode gas diffusion layer 12 of the fuel cell 10 through the fuel distribution layer 30 and the anode conductive layer 18. The fuel supplied to the anode gas diffusion layer 12 is diffused in the anode gas diffusion layer 12 and supplied to the anode catalyst layer 11. When methanol fuel is used as the liquid fuel, an internal reforming reaction of methanol represented by the following formula (1) occurs in the anode catalyst layer 11. The formula (1) is the same as the above-described formula (1).
CH ₃ OH + H ₂ O → CO ₂ + 6H ⁺ + 6e ⁻ Formula (1)

  When pure methanol is used as the methanol fuel, is methanol reformed by water generated in the cathode catalyst layer 14 or water in the electrolyte membrane 17 and the internal reforming reaction of the above formula (1)? Or other reaction mechanisms that do not require water.

Electrons (e ⁻ ) generated by this reaction are guided to the outside through a current collector, and are operated to a cathode (air electrode) 16 after operating a portable electronic device or the like as so-called electricity. Further, protons (H ⁺⁾ generated by the internal reforming reaction of the formula (1) is guided to the cathode (air electrode) 16 through the electrolyte membrane 17. Air is supplied to the cathode (air electrode) 16 as an oxidant. Electrons (e ⁻ ) and protons (H ⁺ ) reaching the cathode (air electrode) 16 cause a reaction shown in the following formula (2) with oxygen in the air in the cathode catalyst layer 14, and accompanying this power generation reaction, Water is produced. This equation (2) is the same as the above-described equation (2).
(3/2) O ₂ + 6e ⁻ + 6H ⁺ → 3H ₂ O Formula (2)

  The first catalyst layer 14 a in the cathode catalyst layer 14 of the cathode (air electrode) 16 mainly improves air diffusibility.

  The internal reforming reaction described above is performed smoothly, and a high output and a stable output can be obtained in the fuel cell 1.

  According to the fuel cell 1 of the first embodiment of the present invention described above, the cathode catalyst layer 14 is composed of the first catalyst layer 14a and the second catalyst layer 14b, and the first catalyst layer 14a is The diffusibility of air is improved in the first catalyst layer 14a by configuring the proton conductive resin contained in the catalyst layer at a lower ratio and / or having a higher porosity than the second catalyst layer 14b. Can be achieved. In addition, by locating the first catalyst layer 14a corresponding to the air inlet 61 of the surface cover 60, it is possible to further improve the air diffusibility in the first catalyst layer 14a. Furthermore, the second catalyst layer 14 b can suppress the water generated in the cathode catalyst layer 14 from being evaporated to the outside air as water vapor, and supply sufficient water to the anode (fuel electrode) 13. Further, in the fuel cell 1 including the cathode catalyst layer 14 having such a configuration, a high output and a stable output can be obtained.

  Next, the fact that the fuel cell according to the present invention has excellent output characteristics will be described based on Examples and Comparative Examples.

(Example 1)
The fuel cell used in Example 1 has the same configuration as the fuel cell 1 shown in FIG. 3, and will be described with reference to FIG.

  First, a method for producing the fuel battery cell 10 will be described.

  To the carbon black supporting the anode catalyst particles (Pt: Ru = 1: 1), a perfluorocarbon sulfonic acid solution as a proton conductive resin and water and methoxypropanol as a dispersion medium were added to support the anode catalyst particles. A paste was prepared by dispersing carbon black. The obtained paste was applied to porous carbon paper (40 mm × 30 mm rectangle) as the anode gas diffusion layer 12 to obtain an anode catalyst layer 11 having a thickness of 100 μm.

  To the carbon black carrying the cathode catalyst particles (Pt), a perfluorocarbon sulfonic acid solution as a proton conductive resin and water and methoxypropanol as a dispersion medium are added to disperse the carbon black carrying the cathode catalyst particles. A paste was prepared. The obtained paste was applied to porous carbon paper as the cathode gas diffusion layer 15 to obtain a first catalyst layer 14a having a thickness of 100 μm. Here, the proportion of the proton conductive resin contained in the first catalyst layer 14a after the drying of the first catalyst layer 14a was 22% by weight. Further, the porosity of the first catalyst layer 14a was measured by a mercury intrusion method and found to be 40%. The porosity of the catalyst layer was measured using Shimadzu Autopore 9520 type under the condition of an initial pressure of about 7 kPa (corresponding to a pore diameter of about 180 μm). At this time, the total pore volume measured using only the cathode gas diffusion layer 15 before applying the first catalyst layer 14a as a sample, and the cathode gas diffusion layer 15 after applying and drying the first catalyst layer 14a The difference from the total pore volume measured as a sample is considered to be equal to the pore volume of only the first catalyst layer 14a, and from the value of the pore volume of only the first catalyst layer 14a, the first catalyst layer The porosity of 14a was calculated.

  Further, a second catalyst layer having a thickness of 100 μm is applied to the porous carbon paper as the cathode gas diffusion layer 15 by applying a paste prepared in the same manner as in the case of forming the first catalyst layer 14a. 14b was obtained. Here, the proportion of the proton conductive resin contained in the second catalyst layer 14b after the drying of the second catalyst layer 14b was 30% by weight. The porosity of the second catalyst layer 14b was 30% as a result of measurement by the mercury intrusion method described above.

  An outer shape of the cathode gas diffusion layer 15 coated with the second catalyst layer 14b is formed in a rectangular shape (40 mm × 30 mm), and a surface cover 60 described later in the cathode gas diffusion layer 15 coated with the second catalyst layer 14b is formed. Forty-eight circular holes having a diameter of 3 mm were uniformly formed at the same position as the formed air inlet 61. Subsequently, 48 disks having a diameter of 3 mm were cut out from the cathode gas diffusion layer 15 coated with the first catalyst layer 14a, and these were cut into holes formed in the cathode gas diffusion layer 15 coated with the second catalyst layer 14b. The catalyst layer was fitted so that the surfaces of the catalyst layer were flush. Thereby, the cathode catalyst layer 14 provided with the 1st catalyst layer 14a and the 2nd catalyst layer 14b was obtained. The anode catalyst layer 11 and the cathode catalyst layer 14 have the same shape and size.

  A perfluorocarbon sulfonic acid membrane (trade name: nafion membrane) having a thickness of 30 μm and a water content of 10 to 20% by weight as the electrolyte membrane 17 between the anode catalyst layer 11 and the cathode catalyst layer 14 produced as described above. The fuel cell 10 was obtained by performing hot pressing in a state where the anode catalyst layer 11 and the cathode catalyst layer 14 face each other.

  Subsequently, the fuel battery cell 10 was sandwiched between gold foils having a plurality of openings to form an anode conductive layer 18 and a cathode conductive layer 19. A rubber O-ring 20 was sandwiched between the electrolyte membrane 17 and the anode conductive layer 18 and between the electrolyte membrane 17 and the cathode conductive layer 19 for sealing.

Further, as the moisture retaining layer 50, the thickness is 1 mm, the air permeability is 2 seconds / 100 cm ³ (according to the measurement method specified in JIS P-8117), and the moisture permeability is 2000 g / (m ² · 24 h) (JIS L A porous film made of polyethylene of −1099 A-1) was cut into a rectangle (44 mm × 34 mm) and laminated on the cathode conductive layer 19. The air supplied from the outside air to the cathode (air electrode) 16 passes through the moisture retaining layer 50.

  On this moisturizing layer 50, a stainless steel plate (SUS304) having a thickness of 1 mm in which 48 air inlets 61 having a rectangular outer shape (44 mm × 34 mm) and a diameter of 3 mm are uniformly formed is disposed. A surface cover 60 was obtained.

  At this time, in the first catalyst layer 14a positioned corresponding to the air inlet 61 of the surface cover 60, the first catalyst layer 14a is formed in each air inlet 61 when viewed in the thickness direction of the fuel cell 1. The other part of the cathode catalyst layer 14 was constituted by the second catalyst layer 14b. Therefore, the total area of the first catalyst layer 14 a on the surface of the cathode catalyst layer 14 was one times the total area of the air inlet 61 of the surface cover 60. Further, in the first catalyst layer 14 a located corresponding to the air inlet 61 of the surface cover 60, the air inlet 61 and the first catalyst layer 14 a overlap when viewed in the thickness direction of the fuel cell 1. The total area of the portions was one times the total area of the air inlet 61.

  Further, an ironing pump was used as the pump 70, and a part of the flow path 44 was squeezed in a certain direction to generate pressure, and the liquid fuel F stored in the fuel storage unit 41 was sent to the fuel supply unit 43. . Here, a control circuit for controlling the rotational speed of the ironing pump by the current flowing through the fuel cell 1 is configured, and the fuel supply amount necessary for causing an electrochemical reaction in the fuel cell 1 (per 1 A of current per minute) The fuel was controlled so that 1.4 times the amount of methanol supplied (3.3 mg) was always supplied.

Then, pure methanol having a purity of 99.9% by weight was supplied to the above-described fuel cell 1 in an environment where the temperature was 25 ° C. and the relative humidity was 50% so that the above supply amount was obtained. A constant voltage power source as an external load is connected, and the current flowing through the fuel cell 1 is controlled so that the output voltage of the fuel cell 1 is constant at 0.3 V. At this time, the output density obtained from the fuel cell 1 Was measured. Here, the output density (mW / cm ² ) of the fuel cell 1 refers to the current density flowing through the fuel cell 1 (current value per 1 cm ² area (mA / cm ² ) of the power generation unit) and the output voltage of the fuel cell 1. Multiplied by. Further, the area of the power generation unit is the area of the portion where the anode catalyst layer 11 and the cathode catalyst layer 14 face each other. In this embodiment, the area of the anode catalyst layer 11 and the area of the cathode catalyst layer 14 (the sum of the areas of the first catalyst layer 14a and the second catalyst layer 14b) are equal and completely opposed to each other. The area of the part is equal to the area of these catalyst layers.

  Table 1 shows the measurement results. Here, the relative output density when the output density in Comparative Example 1 described later is 100 is shown.

(Example 2)
In the fuel cell 1 used in Example 2, the production method of the cathode catalyst layer 14 is different from that of the fuel cell 1 used in Example 1, but the other configuration is the same as that of the fuel cell 1 used in Example 1. As with the cathode catalyst layer 14 of Example 1, the total area of the first catalyst layer 14 a on the surface of the cathode catalyst layer 14 was set to be one time the total area of the air inlet 61 of the surface cover 60. . Further, in the first catalyst layer 14 a located corresponding to the air inlet 61 of the surface cover 60, the air inlet 61 and the first catalyst layer 14 a overlap when viewed in the thickness direction of the fuel cell 1. The total area of the portions was one time the total area of the air inlet 61.

  A method for producing the cathode catalyst layer 14 will be described.

  To the carbon black carrying the cathode catalyst particles (Pt), a perfluorocarbon sulfonic acid solution as a proton conductive resin and water and methoxypropanol as a dispersion medium are added to disperse the carbon black carrying the cathode catalyst particles. A paste was prepared. A first mask cut out in a shape for applying the first catalyst layer 14a was placed on the porous carbon paper as the cathode gas diffusion layer 15, and the obtained paste was applied. When the first mask was removed after the paste was dried, the first catalyst layer 14a was obtained at a predetermined position. Here, the proportion of the proton conductive resin contained in the first catalyst layer 14a after the drying of the first catalyst layer 14a was 22% by weight. Further, the porosity of the first catalyst layer 14a was measured by the mercury intrusion method in the same manner as in Example 1, and as a result, it was 40%.

  Subsequently, a second mask cut out in a shape to apply the second catalyst layer 14b is disposed on the cathode gas diffusion layer 15 on which the first catalyst layer 14a is formed, and the catalyst prepared in the same manner as described above. The paste was applied. When the paste was dried and the second mask was removed, the second catalyst layer 14b was obtained at a predetermined position. Here, the proportion of the proton conductive resin contained in the second catalyst layer 14b after the drying of the second catalyst layer 14b was 30% by weight. The porosity of the second catalyst layer 14b was 30% as a result of measurement by the mercury intrusion method described above.

  Thus, the cathode catalyst layer 14 provided with the 1st catalyst layer 14a and the 2nd catalyst layer 14b was obtained. Further, the manufacturing method of the constituent parts of the other fuel cell 1 was the same as that of the fuel cell 1 used in Example 1.

  Further, the measurement method, measurement conditions, calculation method, and the like of the power density were the same as those in Example 1. Table 1 shows the measurement results. Here, the relative output density when the output density in Comparative Example 1 described later is 100 is shown.

(Example 3)
In the fuel cell 1 used in Example 3, the production method of the cathode catalyst layer 14 is different from that of the fuel cell 1 used in Example 1, but the other configuration is the same as that of the fuel cell 1 used in Example 1. As with the cathode catalyst layer 14 of Example 1, the total area of the first catalyst layer 14 a on the surface of the cathode catalyst layer 14 was set to be one time the total area of the air inlet 61 of the surface cover 60. . Further, in the first catalyst layer 14 a located corresponding to the air inlet 61 of the surface cover 60, the air inlet 61 and the first catalyst layer 14 a overlap when viewed in the thickness direction of the fuel cell 1. The total area of the portions was one time the total area of the air inlet 61.

  A method for producing the cathode catalyst layer 14 will be described.

  To the carbon black carrying the cathode catalyst particles (Pt), a perfluorocarbon sulfonic acid solution as a proton conductive resin and water and methoxypropanol as a dispersion medium are added to disperse the carbon black carrying the cathode catalyst particles. A paste was prepared. The obtained paste was applied to porous carbon paper as the cathode gas diffusion layer 15 and dried to obtain a first catalyst layer 14a. Here, the proportion of the proton conductive resin contained in the first catalyst layer 14a after the drying of the first catalyst layer 14a was 26% by weight.

On the formed first catalyst layer 14a, circular holes with a diameter of 3 mm are evenly 48 so as to be in the same position as the air inlet 61 formed in the surface cover 60 having a rectangular outer shape (40 mm × 30 mm). A formed stainless steel plate (SUS304) having a thickness of 1 mm was placed and compressed vertically by a press at a pressure of 40 kgf / cm ² . Thereafter, when the stainless steel plate was removed, the portion compressed by the stainless steel plate constituted the second catalyst layer 14b, and the portion not compressed by the stainless steel plate constituted the first catalyst layer 14a. Each porosity was measured by the mercury intrusion method in the same manner as in Example 1. As a result, the first catalyst layer 14a was 35% and the second catalyst layer 14b was 20%. The proportion of the proton conductive resin contained in the second catalyst layer 14b after the drying of the second catalyst layer 14b is 26% by weight, which is the same as that of the first catalyst layer 14a.

  Thus, the cathode catalyst layer 14 provided with the 1st catalyst layer 14a and the 2nd catalyst layer 14b was obtained. Further, the manufacturing method of the constituent parts of the other fuel cell 1 was the same as that of the fuel cell 1 used in Example 1.

  Further, the measurement method, measurement conditions, calculation method, and the like of the power density were the same as those in Example 1. Table 1 shows the measurement results. Here, the relative output density when the output density in Comparative Example 1 described later is 100 is shown.

(Example 4)
Used in Example 1 except that the diameter of the first catalyst layer 14a is 2.2 mm, and the first catalyst layer 14a is arranged so that the center of each of the first catalyst layer 14a and the air inlet 61 of the surface cover 60 is aligned. The fuel cell 1 was the same.

  At this time, the total area of the first catalyst layer 14 a on the surface of the cathode catalyst layer 14 was 0.54 times the total area of the air inlet 61 of the surface cover 60. Further, in the first catalyst layer 14 a located corresponding to the air inlet 61 of the surface cover 60, the air inlet 61 and the first catalyst layer 14 a overlap when viewed in the thickness direction of the fuel cell 1. The total area of the portions was 0.54 times the total area of the air inlet 61. Further, the manufacturing method of the constituent parts of the other fuel cell 1 was the same as that of the fuel cell 1 used in Example 1.

  Further, the measurement method, measurement conditions, calculation method, and the like of the power density were the same as those in Example 1. Table 1 shows the measurement results. Here, the relative output density when the output density in Comparative Example 1 described later is 100 is shown.

(Example 5)
Used in Example 1 except that the diameter of the first catalyst layer 14a is 3.6 mm, and the first catalyst layer 14a is disposed so that the center of each of the first catalyst layer 14a and the air inlet 61 of the surface cover 60 is aligned. The fuel cell 1 was the same.

  At this time, the total area of the first catalyst layer 14 a on the surface of the cathode catalyst layer 14 was 1.44 times the total area of the air inlet 61 of the surface cover 60. Further, in the first catalyst layer 14 a located corresponding to the air inlet 61 of the surface cover 60, the air inlet 61 and the first catalyst layer 14 a overlap when viewed in the thickness direction of the fuel cell 1. The total area of the portions was 1.44 times the total area of the air inlet 61. Further, the manufacturing method of the constituent parts of the other fuel cell 1 was the same as that of the fuel cell 1 used in Example 1.

  Further, the measurement method, measurement conditions, calculation method, and the like of the power density were the same as those in Example 1. Table 1 shows the measurement results. Here, the relative output density when the output density in Comparative Example 1 described later is 100 is shown.

(Example 6)
FIG. 4 schematically shows the overlapping state of the first catalyst layer 14 a and the air inlet 61 of the surface cover 60 in the cathode catalyst layer 14 used in Example 6 when viewed in the thickness direction of the fuel cell 1. It is the shown top view.

  The diameter of the first catalyst layer 14a is 3 mm, and as shown in FIG. 4, the center X of each first catalyst layer 14a corresponds to each first catalyst layer 14a. Example 1 except that the first catalyst layer 14a is disposed so that the distance between the center X of the first catalyst layer 14a and the center Y of the air inlet 61 of the surface cover 60 is 1.5 mm. The same as the fuel cell 1 used in FIG.

  At this time, the total area of the first catalyst layer 14 a on the surface of the cathode catalyst layer 14 is one times the total area of the air inlet 61 of the surface cover 60, that is, the first catalyst on the surface of the cathode catalyst layer 14. The total area of the layers 14a and the total area of the air inlets 61 of the surface cover 60 were configured to be equal. Further, in the first catalyst layer 14 a located corresponding to the air inlet 61 of the surface cover 60, the air inlet 61 and the first catalyst layer 14 a overlap when viewed in the thickness direction of the fuel cell 1. The total area of the portions was 0.39 times the total area of the air inlet 61. Further, the manufacturing method of the constituent parts of the other fuel cell 1 was the same as that of the fuel cell 1 used in Example 1.

  Further, the measurement method, measurement conditions, calculation method, and the like of the power density were the same as those in Example 1. Table 1 shows the measurement results. Here, the relative output density when the output density in Comparative Example 1 described later is 100 is shown.

(Comparative Example 1)
In the fuel cell used in Comparative Example 1, the cathode catalyst layer 14 is not composed of the first catalyst layer 14a and the second catalyst layer 14b, but is composed of one type of catalyst layer. 1 was the same as the fuel cell 1 used in 1. That is, the total area of the first catalyst layer 14 a on the surface of the cathode catalyst layer 14 is “0” times the total area of the air inlet 61 of the surface cover 60. Further, in the first catalyst layer 14 a located corresponding to the air inlet 61 of the surface cover 60, the air inlet 61 and the first catalyst layer 14 a overlap when viewed in the thickness direction of the fuel cell 1. The total area of the portions is “0” times the total area of the air inlet 61.

  A method for producing the cathode catalyst layer 14 will be described.

  To the carbon black carrying the cathode catalyst particles (Pt), a perfluorocarbon sulfonic acid solution as a proton conductive resin and water and methoxypropanol as a dispersion medium are added to disperse the carbon black carrying the cathode catalyst particles. A paste was prepared. On the porous carbon paper as the cathode gas diffusion layer 15, the obtained paste was applied and dried to obtain a cathode catalyst layer 14. Here, the proportion of the proton conductive resin contained in the cathode catalyst layer 14 after drying was 26% by weight. Further, the porosity of the cathode catalyst layer 14 was measured by the mercury intrusion method in the same manner as in Example 1. As a result, it was 35%. Further, the manufacturing method of the constituent parts of the other fuel cell 1 was the same as that of the fuel cell 1 used in Example 1.

  Further, the measurement method, measurement conditions, calculation method, and the like of the power density were the same as those in Example 1. Table 1 shows the measurement results. Here, the output density in Comparative Example 1 is shown as 100. Here, since the cathode catalyst layer 14 is composed of one type of catalyst layer, the ratio of the proton conductive resin and the porosity in the first catalyst layer and the second catalyst layer in Table 1 are as follows. The value is the same value.

(Comparative Example 2)
The fuel used in Example 1 except that the diameter of the first catalyst layer 14a is 2 mm, and the first catalyst layer 14a is arranged so that the center of each of the first catalyst layer 14a and the air inlet 61 of the surface cover 60 is aligned. Same as battery 1.

  At this time, the total area of the first catalyst layer 14 a on the surface of the cathode catalyst layer 14 was 0.44 times the total area of the air inlet 61 of the surface cover 60. Further, in the first catalyst layer 14 a located corresponding to the air inlet 61 of the surface cover 60, the air inlet 61 and the first catalyst layer 14 a overlap when viewed in the thickness direction of the fuel cell 1. The total area of the portions was 0.44 times the total area of the air inlet 61. Further, the manufacturing method of the constituent parts of the other fuel cell 1 was the same as that of the fuel cell 1 used in Example 1.

  Further, the measurement method, measurement conditions, calculation method, and the like of the power density were the same as those in Example 1. Table 1 shows the measurement results. Here, the relative output density when the output density in Comparative Example 1 is set to 100 is shown.

(Comparative Example 3)
The fuel used in Example 1 except that the diameter of the first catalyst layer 14a is 4 mm, and the first catalyst layer 14a is disposed so that the center of each of the first catalyst layer 14a and the air inlet 61 of the surface cover 60 is aligned. Same as battery 1.

  At this time, the total area of the first catalyst layer 14 a on the surface of the cathode catalyst layer 14 was 1.78 times the total area of the air inlet 61 of the surface cover 60. Further, in the first catalyst layer 14 a located corresponding to the air inlet 61 of the surface cover 60, the air inlet 61 and the first catalyst layer 14 a overlap when viewed in the thickness direction of the fuel cell 1. The total area of the portions was 1.78 times the total area of the air inlet 61. Further, the manufacturing method of the constituent parts of the other fuel cell 1 was the same as that of the fuel cell 1 used in Example 1.

  Further, the measurement method, measurement conditions, calculation method, and the like of the power density were the same as those in Example 1. Table 1 shows the measurement results. Here, the relative output density when the output density in Comparative Example 1 is set to 100 is shown.

(Comparative Example 4)
FIG. 5 schematically shows the overlapping state of the first catalyst layer 14 a and the air inlet 61 of the surface cover 60 in the cathode catalyst layer 14 used in Comparative Example 4 when viewed in the thickness direction of the fuel cell 1. It is the shown top view.

  The diameter of the first catalyst layer 14a is 3 mm. As shown in FIG. 5, the center X of each first catalyst layer 14a and the air inlet 61 of the surface cover 60 corresponding to each first catalyst layer 14a. The fuel cell 1 was the same as the fuel cell 1 used in Example 1, except that the distance from the center Y was 2.1 mm.

  At this time, the total area of the first catalyst layer 14 a on the surface of the cathode catalyst layer 14 is one times the total area of the air inlet 61 of the surface cover 60, that is, the first catalyst on the surface of the cathode catalyst layer 14. The total area of the layers 14a and the total area of the air inlets 61 of the surface cover 60 were configured to be equal. Further, in the first catalyst layer 14 a located corresponding to the air inlet 61 of the surface cover 60, the air inlet 61 and the first catalyst layer 14 a overlap when viewed in the thickness direction of the fuel cell 1. The total area of the portions was 0.18 times the total area of the air inlet 61. Further, the manufacturing method of the constituent parts of the other fuel cell 1 was the same as that of the fuel cell 1 used in Example 1.

  Further, the measurement method, measurement conditions, calculation method, and the like of the power density were the same as those in Example 1. Table 1 shows the measurement results. Here, the relative output density when the output density in Comparative Example 1 is set to 100 is shown.

(Summary of Examples 1 to 6 and Comparative Examples 1 to 4)
Table 1 shows the relative power densities in Examples 1 to 6 and Comparative Examples 1 to 4.

  As shown in Table 1, it was found that the fuel cells in Examples 1 to 6 had a higher relative output density than the fuel cells in Comparative Examples 1 to 4. That is, the total area of the first catalyst layer 14 a on the surface of the cathode catalyst layer 14 is 0.5 to 1.5 times the total area of the air inlet 61 of the surface cover 60, and In the first catalyst layer 14a positioned corresponding to the air inlet 61, the total area of the portions where the air inlet 61 and the first catalyst layer 14a overlap when viewed in the thickness direction of the fuel cell 1 is It was found that the relative output density was high under the condition that the total area of the air inlet 61 was 0.3 times or more.

  The present invention can be applied to various fuel cells using liquid fuel. Further, the specific configuration of the fuel cell and the supply state of the fuel are not particularly limited. For example, the liquid fuel is directly circulated under the anode conductive layer, or the liquid fuel is evaporated outside the fuel cell. Various forms, such as an external vaporization type in which vaporized gaseous fuel flows under the anode conductive layer, an internal vaporization type in which liquid fuel is accommodated in the fuel accommodating portion, and the liquid fuel is vaporized inside the cell and supplied to the anode catalyst layer The present invention can be applied to. In the implementation stage, the constituent elements can be modified and embodied without departing from the technical idea of the present invention. Furthermore, various modifications are possible, such as appropriately combining a plurality of components shown in the above embodiment, or deleting some components from all the components shown in the embodiment. Embodiments of the present invention can be expanded or modified within the scope of the technical idea of the present invention, and these expanded and modified embodiments are also included in the technical scope of the present invention.

It is sectional drawing which shows the structure of the fuel cell of one embodiment which concerns on this invention. The top view of a cathode catalyst layer. Sectional drawing which shows the structure at the time of providing the pump in the fuel cell of 1st Embodiment based on this invention. The top view which showed typically the overlapping state of the 1st catalyst layer in the cathode catalyst layer used in Example 6, and the air inlet of a surface cover when it sees in the thickness direction of a fuel cell. The top view which showed typically the overlapping state of the 1st catalyst layer in the cathode catalyst layer used in the comparative example 4, and the air inlet of a surface cover when it sees in the thickness direction of a fuel cell.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Fuel cell, 10 ... Fuel cell, 11 ... Anode catalyst layer, 12 ... Anode gas diffusion layer, 13 ... Anode (fuel electrode), 14 ... Cathode catalyst layer, 14a ... First catalyst layer, 14b ... Second Catalyst layer, 15 ... cathode gas diffusion layer, 16 ... cathode (air electrode), 17 ... electrolyte membrane, 18 ... anode conductive layer, 19 ... cathode conductive layer, 20 ... O-ring, 30 ... fuel distribution layer, 31 ... opening , 40 ... Fuel supply mechanism, 41 ... Fuel storage unit, 42 ... Fuel supply unit body, 43 ... Fuel supply unit, 44 ... Channel, 50 ... Moisturizing layer, 60 ... Surface cover, 61 ... Air inlet, F ... Liquid fuel.

Claims (6)

A membrane electrode assembly having a fuel electrode, an air electrode, and an electrolyte membrane sandwiched between the fuel electrode and the air electrode;
A moisturizing layer disposed on the air electrode,
A fuel cell comprising: a surface cover having an air inlet, which is laminated on the moisturizing layer,
The cathode catalyst layer of the air electrode,
A first catalyst layer positioned corresponding to the air inlet of the surface cover;
And a second catalyst layer constituting a portion other than the first catalyst layer.   2. The fuel cell according to claim 1, wherein the first catalyst layer has a lower proportion of the proton conductive resin contained in the catalyst layer than the second catalyst layer.   The fuel cell according to claim 1, wherein the first catalyst layer has a higher porosity than the second catalyst layer.   4. The cathode catalyst layer according to claim 1, wherein the cathode catalyst layer is configured by combining the first catalyst layer and the second catalyst layer that are separately formed. 5. Fuel cell.   4. The fuel cell according to claim 1, wherein the second catalyst layer of the cathode catalyst layer is configured by compressing a predetermined portion of the first catalyst layer. 5.   The total area of the first catalyst layer on the surface of the cathode catalyst layer is 0.5 to 1.5 times the total area of the air inlet of the surface cover, and the air inlet of the surface cover In the first catalyst layer located corresponding to the thickness of the fuel cell, the total area of the portions where the air inlet and the first catalyst layer overlap is the sum of the air inlets. The fuel cell according to any one of claims 1 to 5, wherein the fuel cell is 0.3 times or more of a total area.

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