WO2007110941A1 - Fuel cell - Google Patents

Abstract

[PROBLEMS] To provide a fuel cell that including realization of satisfactory fuel supply at the time of high-load discharge, facilitates controlling of the velocity of transportation of methanol as a fuel, and that is equipped with a fuel vaporization part of low cost ensuring high durability. [MEANS FOR SOLVING PROBLEMS] There is provided a fuel cell comprising proton-conductive solid electrolyte layer (22) and, interposing the same, fuel electrode (23) for feeding of vaporized fuel to the solid electrolyte layer and air electrode (21) for feeding of oxygen to the solid electrolyte layer, the fuel employed being a liquid fuel, wherein fuel vaporizing part (47) for vaporizing the liquid fuel has fuel vaporizing membrane (49) containing a sulfonic acid polymer and another polymer, the fuel vaporizing membrane (49) having its interior dotted with particles of the other polymer and having a mechanical strength higher than that of membrane of the sulfonic acid polymer.

Description

 Specification

 Fuel cell

 Technical field

 TECHNICAL FIELD [0001] The present invention relates to a direct methanol type fuel cell, and more particularly to a vaporization supply type fuel cell including a low-cost and highly durable fuel vaporization unit.

 Background art

 [0002] With the increase in functionality and performance of portable electronic devices such as mobile phones, personal digital assistants, notebook computers, etc., there is a need to improve the performance of batteries that serve as drive power sources.

[0003] Currently, lithium-ion secondary batteries are mainly used as the drive power source for portable electronic devices, and there is a limit in improving the power energy density (the amount of energy stored per unit mass). For some reasons, fuel cells are attracting attention as an alternative to this due to inconvenience of charging.

 [0004] A fuel cell has a much higher energy density than a lithium ion battery, and does not require charging. In particular, direct methanol fuel cells (DMFC), which generate electricity by supplying organic fuel such as methanol directly onto the electrode, do not use a reformer that reforms organic fuel into hydrogen. It is particularly easy to reduce the size and weight, and is suitable as a power source for portable electronic devices.

 [0005] In DMFC, by supplying methanol from the liquid fuel reservoir to the catalyst layer of the fuel electrode, protons (H +), electrons (e—), and carbon dioxide are generated on the catalyst ( Reaction formula: CH

 Three

OH + H 0 → CO + 6H + + 6e—), protons permeate the polymer solid electrolyte membrane,

twenty two

 It combines with oxygen in the air electrode catalyst layer to produce water. At this time, by connecting the fuel electrode and the air electrode to an external circuit, electric power can be taken out by the generated electrons.

[0006] The fuel supply method in the DMFC fuel cell can be classified into a liquid supply type in which liquid fuel is directly supplied to the surface of a large fuel electrode and a vaporization supply type in which liquid fuel is vaporized and then supplied to the electrode section. .

[0007] In the liquid supply type, when a high-concentration methanol solution is used as the fuel, the electrolyte membrane is methanol. The high-concentration solution permeates the methanol and does not contribute to power generation. As a result, methanol increases, and so-called methanol crossover that causes a decrease in the performance of the air electrode occurs.

 [0008] On the other hand, in the vaporization supply type, liquid fuel is vaporized by the fuel vaporization section, and gaseous methanol is supplied to the fuel electrode. Such a vaporization supply type avoids the problem of methanol crossover and makes it possible to increase the concentration of fuel. As a result, energy density is improved. Note that a vaporization film having a function of vaporizing a liquid is generally used for the fuel vaporization unit.

 [0009] As a method for vaporizing liquid fuel using the vaporized membrane, a method using a carbon porous plate as the vaporized membrane has been proposed (see Patent Document 1). The aqueous methanol solution is transported through the pores of the carbon porous plate with an average pore diameter of 5 m using capillary force. Then, it is vaporized on the fuel electrode side surface of the carbon porous plate having an average pore diameter of 100 / zm.

 Patent Document 1: Japanese Unexamined Patent Publication No. 2000-106201

 Disclosure of the invention

[0010] (Problems to be solved by the invention)

 However, in the example of Patent Document 1, since the capillary force is used for transporting the methanol aqueous solution, the high load discharge required for the portable electronic device in which the fuel transport speed in the carbon porous membrane is slow. When this is done, there is a problem that a shortage of methanol will occur.

 [0011] Also, under normal use conditions, force S that needs to be appropriately controlled so that the rate of transporting methanol does not become excessive S, two types of carbon porous materials with different pore sizes used in Patent Document i It is not easy to manufacture a membrane by controlling the pore diameter so as to satisfy such conditions.

 [0012] Furthermore, it is essential to have durability and low cost so as not to be damaged even when high load discharge is repeatedly performed.

[0013] The present invention has been made in view of the above problems, and it is easy to control the speed of transporting methanol as a fuel, including the realization of sufficient fuel supply during high-load discharge. In addition, a fuel cell having a low-cost fuel vaporization section that can ensure durability The purpose is to provide.

 [0014] (Means for solving the problem)

 The present inventor has found that the above problem can be solved by using a membrane having a mixed polymer force including a sulfonic acid-based polymer and another polymer as a fuel vaporization membrane. It came to an eggplant.

That is, a low cost can be realized by mixing a predetermined amount of another polymer material that is available at low cost with a sulfonic acid-based polymer material that is currently expensive.

[0016] In addition, by changing the mixing ratio at the time of manufacture, the amount of other polymer that is difficult to permeate the fuel in the fuel vaporized film changes (spotted), so the fuel transportation speed can be easily increased. It can also be controlled.

 [0017] According to one aspect of the present invention, the fuel cell of the present invention includes a fuel electrode to which vaporized fuel is supplied to the solid electrolyte layer with the proton conductive solid electrolyte layer interposed therebetween, and the solid electrolyte. A fuel cell that uses liquid fuel as a fuel, and includes a sulfonic acid-based polymer and another polymer in the fuel vaporization section that vaporizes the liquid fuel. The fuel vaporized film is interspersed with particles of the other polymer, and the mechanical strength of the fuel vaporized film is higher than the mechanical strength of the film made of the sulfonic acid polymer. It is characterized by that.

 [0018] Further, according to another aspect of the present invention, the fuel cell of the present invention includes a fuel electrode to which vaporized fuel is supplied to the solid electrolyte layer with the proton conductive solid electrolyte layer interposed therebetween. An air electrode to which oxygen is supplied to the solid electrolyte layer, and a fuel cell using liquid fuel as a fuel, a sulfonic acid polymer in the fuel vaporization section for vaporizing the liquid fuel, and It has a fuel vaporization film containing another polymer having a methanol permeation rate slower than that of a sulfonic acid polymer, and the fuel vaporization film is dotted with particles of the other polymer inside. To do.

 [0019] (Effect of the invention)

According to the present invention, in the fuel cell of the present invention, by using a membrane containing a sulfonic acid polymer and the above-mentioned other polymer as the fuel vaporization membrane, it is easy to control the speed at which the fuel is transported. In addition, it is possible to ensure durability and low cost fuel cells Can be provided.

 Brief Description of Drawings

 FIG. 1 is a schematic cross-sectional view showing a configuration of a fuel cell according to Example 1 of the present invention.

 FIG. 2 is a schematic diagram showing the dispersion state of other polymers in the fuel vaporization membrane according to Example 1 of the present invention.

 [FIG. 3] is a diagram showing a rupture of a fuel vaporized film.

 FIG. 4 is a characteristic diagram showing changes in the number of discharges and discharge capacity in Example 1 and Comparative Example.

 FIG. 5 is a perspective view schematically showing the appearance of the fuel cell.

 FIG. 6 is a schematic cross-sectional view showing a modification of the main configuration of the fuel cell.

 BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, details according to embodiments of the present invention will be described with reference to the drawings.

[0022] (Example 1)

 FIG. 1 is a schematic cross-sectional view showing a configuration of a fuel cell according to Example 1 of the present invention. As shown in FIG. 1, the fuel cell 10 includes a power generation unit 20, an air supply unit 30 that supplies oxygen gas contained in the air to the power generation unit 20, and a fuel gas such as methanol gas by vaporizing liquid fuel. It consists of a fuel supply unit 40 and the like that supplies the power generation unit 20.

 [0023] Power generation section

 The power generation unit 20 is configured by laminating an air electrode 21, a solid electrolyte layer 22, and a fuel electrode 23 in this order. This power generation unit 20 is also called a membrane electrode assembly (MEA) and affects the performance of the fuel cell.

 The air electrode 21 is composed of a force not shown because it is a thin film, for example, a porous carbon paper and a catalyst layer. The catalyst layer also has, for example, Pt (platinum) fine particles and carbon powder force having Pt supported on the surface, and is disposed so as to be in contact with the solid electrolyte layer 22.

[0025] The solid electrolyte layer 22 is made of a proton-conductive polymer solid electrolyte. Examples of such a polymer electrolyte include a resin having a strong acid group such as a sulfone group and a phosphate group and a weak acid group such as a carboxyl group. The solid electrolyte layer 22 is, for example, NAPION (registered trademark) NF117 (trade name) manufactured by DuPont, or Aciplex (trade name) manufactured by Asahi Kasei. ) Can be used.

 [0026] The fuel electrode 23 is composed of a force not shown because it is a thin film, for example, a porous carbon paper and a catalyst layer. The catalyst layer is made of, for example, fine particles of a Pt—Ru (ruthenium) alloy or a carbon powder carrier carrying a Pt—Ru alloy on the surface, and is disposed so as to be in contact with the solid electrolyte layer 22.

 In the power generation unit 20, fuel gas is supplied to the fuel electrode 23. As the liquid fuel that is the basis of the fuel gas, for example, methanol, ethanol, dimethyl ether of approximately 100% concentration, or an aqueous solution thereof can be used. In this embodiment, an aqueous methanol solution will be described as an example.

 [0028] In the catalyst layer of the fuel electrode 23, the reaction of the following reaction formula 1 proceeds, the fuel gas methanol gas and water vapor are consumed, carbon dioxide gas, proton (H +), electrons (e-), etc. Is generated.

 CH OH + H 0 → CO + 6H + + 6e—… (Scheme 1)

 3 2 2

 Protons are conducted through the solid electrolyte layer 22 and reach the air electrode 21. On the other hand, the electrons perform work on a load connected as an external circuit (not shown) to the fuel cell 10 via the fuel gas diffusion layer 54 and the anode current collector 53. Further, the electrons reach the air electrode 21 through the air electrode current collector 33 and the air electrode gas diffusion layer 34. In the catalyst layer of the air electrode 21, the reaction of the following reaction formula 2 proceeds, and protons, electrons, and oxygen gas are consumed and water vapor is generated.

3/20 + 6H ⁺ + 6e "→ 3H 2 O (Reaction Formula 2)

 twenty two

 [0030] The generated water vapor is discharged to the outside through the air electrode gas diffusion layers 32 and 34 and the oxygen supply port 3 la. Further, the carbon dioxide gas generated at the fuel electrode 23 is discharged to the outside by a generation gas discharge section (not shown). In this manner, the fuel cell 10 generates power using the methanol aqueous solution as the liquid fuel.

 [0031] One air supply unit

The air supply unit 30 diffuses the oxygen gas introduced from the air electrode side casing 31 and the oxygen supply port 31a of the air electrode side casing 31, and introduces oxygen gas into the air electrode 21. , 34 and the air electrode current collector 33. [0032] The air electrode side casing 31 is made of a metal material or a resin material. The resin material is not particularly limited, but in terms of resistance to alcohols such as methanol, polyolefins such as polyethylene and polypropylene, fluorine resins such as PTFE and PFA, polychlorinated butyl, polybutylene terephthalate, polyethylene naphthalate, poly It is preferable to use a resin such as ether sulfone, polysulfone, polyphenylene oxide, polyether ether ketone, and acrylic.

 [0033] Further, the air electrode side housing 31 is provided with a large number of oxygen supply ports 31a penetrating in the thickness direction. The oxygen supply port 3 la is preferably provided so that oxygen gas is uniformly introduced into the entire air electrode gas diffusion layer 32.

[0034] The air electrode gas diffusion layer 32 is made of a porous material. The porous material is not particularly limited as long as it is porous, but suitable porous materials include, for example, a ceramic porous body, a carbon paper, a carbon fiber non-woven fabric, and a fluororesin porous body. And a polypropylene porous body.

The air electrode current collector 33 is conductive and has a mesh or porous structure. The air electrode current collector 33 allows oxygen gas to pass through the air electrode gas diffusion layer 32 to the air electrode gas diffusion layer 34 side.

 [0036] In addition, the air electrode current collector 33 preferably has a metal material strength with high corrosion resistance such as Ni, SUS304, SUS316 or the like. Further, examples of the structure of the air electrode current collector 33 include a metal mesh, an expanded metal, a metal nonwoven fabric, and a foam metal having a three-dimensional network structure. The air electrode current collector 33 preferably has a highly conductive and highly corrosion-resistant metal film, such as an Au film or an Au alloy film, formed on the surface thereof. By providing such a metal film, it is possible to improve the corrosion resistance of the air electrode current collector 33 and reduce the contact resistance with the air electrode gas diffusion layer 34.

 [0037] The air electrode gas diffusion layer 34 is made of a conductive porous material. Examples of the conductive porous material include carbon paper and carbon fiber nonwoven fabric.

[0038] In the air supply unit 30, oxygen gas in the air is introduced from the oxygen supply port 31a of the air electrode side housing 31, and the oxygen gas diffuses through the openings or pores of the air electrode gas diffusion layers 32 and 34. Then, it is uniformly introduced into the surface of the air electrode 21. Air electrode gas diffusion layer 32 and Z Alternatively, the air electrode gas diffusion layer 34 is not essential if oxygen can be sufficiently supplied to the surface of the air electrode 21 without providing them.

 Note that FIG. 5 shows an arrangement example of the oxygen supply port 31a. FIG. 5 is a perspective view schematically showing the appearance of the fuel cell.

 [0040] The sealing material 55 is made of a resin having excellent airtightness, for example, an epoxy resin or an olefin-based resin. The sealing material 55 is a gas such as methanol gas or carbon dioxide or carbon dioxide inside the fuel cell 10, or a methanol aqueous solution. And the like are prevented from leaking outside the fuel cell 10. Further, the sealing material 55 is similarly used in the fuel supply unit 40 described below.

 [0041] Fuel supply unit

 The fuel supply unit 40 includes a fuel electrode side casing 41, a fuel storage unit 42 filled with an aqueous methanol solution, a fuel vaporization unit 47 that vaporizes methanol in the aqueous methanol solution and converts it into methanol gas, and diffuses the methanol gas. The fuel gas diffusion layers 52 and 54 to be introduced into the fuel electrode 23, the fuel electrode current collector 53, and the like. In the present embodiment, an example in which the main component of the fuel vaporization unit 47 is only the fuel vaporization film 49 will be described, but the fuel vaporization unit 47 is changed to the constituent fuel vaporization film 49 (improves function). ) It is also possible to combine other components.

 [0042] The fuel electrode side housing 41 is made of a metal material or a resin material. The resin material is not particularly limited, but is preferably selected from the same resin materials as those for the air electrode side housing 31 described above in terms of resistance to alcohol such as methanol.

 The fuel storage unit 42 is a gap that is sandwiched between the fuel electrode side casing 41 and the fuel vaporization film 49. An aqueous methanol solution is supplied from the fuel cartridge 43 to the fuel storage unit 42 via the fuel supply port 44. The aqueous methanol solution in the fuel storage unit 42 contacts the surface of the fuel vaporization film 49.

 The fuel cartridge 43 stores an aqueous methanol solution and supplies it to the fuel storage unit 42. The supply power source of the methanol aqueous solution is not particularly limited. For example, a pump (not shown) or a pressure application unit 45 described below may be used in combination. The fuel supply port 44 may be provided with a valve that controls the inflow and backflow of aqueous methanol!

The pressure application unit 45 is provided in the fuel cartridge 43. The pressure application unit 45 increases the vaporization rate of methanol in the fuel vaporization film 49 by applying a back pressure to the methanol aqueous solution. And the supply rate of methanol gas can be increased.

 The pressure application unit 45 applies a back pressure directly to the methanol aqueous solution filled in the fuel cartridge 43 or via a gas such as nitrogen gas. The magnitude of the back pressure is preferably set in the range of 10 kPa to 100 kPa as appropriate depending on the material of the fuel vaporization film 49. The pressure application unit 45 may be directly connected to the fuel storage unit 42 and the back pressure may be directly applied to the methanol aqueous solution filled in the fuel storage unit 42. In this case, however, a valve will be installed to prevent the methanol from flowing back into the fuel cartridge 43. Further, the pressure application unit 45 is not essential when a sufficient methanol aqueous solution is supplied to the fuel vaporization film 49! / ヽ.

 [0047] Regarding the fuel vaporization film 49 in the fuel vaporization unit 47, a force described in detail later. The methanol water solution can be converted into methanol gas, and the methanol gas supply rate to the fuel electrode 23 can be controlled with a simple structure.

 [0048] The fuel gas diffusion layer 52 is made of a porous material having alcohol resistance such as methanol. Examples of the porous material suitable for the fuel gas diffusion layer 52 include porous materials such as ceramic, carbon pentinocarbon fiber nonwoven fabric, fluorine resin, and polypropylene. Further, the porosity of the fuel gas diffusion layer 52 is preferably set in the range of 30% to 95%, more preferably in the range of 40% to 90%. If the porosity exceeds 95%, the mechanical strength of the fuel gas diffusion layer 52 decreases.

 [0049] The thickness of the fuel gas diffusion layer 52 is not particularly limited, but is preferably 1 mm or less. This is because if the fuel gas diffusion layer 52 is thicker than lmm, the total thickness of the fuel cell is likely to be excessively increased. Although it is preferable to provide the fuel gas diffusion layer 52 as described above, it is not essential when the fuel gas is sufficiently diffused.

 The fuel electrode current collector 53 is made of the same material as the air electrode current collector 33, and a highly conductive and highly corrosion-resistant metal film, for example, a film made of Au is formed on the surface thereof. I prefer that.

 [0051] The fuel gas diffusion layer 54 is composed of a conductive porous material having resistance to alcohol such as methanol. Examples of the conductive porous material include carbon paper and carbon fiber nonwoven fabric.

[0052] As described above, the fuel supply unit 40 is a water-soluble methanol solution supplied to the fuel storage unit 42. The liquid is vaporized by the fuel vaporization film 49, methanol gas is supplied to the fuel electrode 23, and electrons and protons are generated by the reaction of the above reaction formula 1.

[0053] It should be noted that the configuration of FIG. 1 described here may be a configuration in which the power generation unit 20 is disposed on both sides of the fuel supply unit 40, as shown in FIG. 6 (modified example of the main configuration of the fuel cell). .

Next, the fuel vaporization film 49 will be described in detail.

 [0055] The fuel vaporization membrane 49 mainly has a material force obtained by mixing a sulfonic acid-based polymer with another polymer other than the sulfonic acid-based polymer. For example, as shown in FIG. 2, the fuel vaporization film 49 is scattered in the state of being dispersed in other polymer 72 particles (diameter of about 2 μm) 1S sulfonic acid-based polymer 71. The thickness of the fuel vaporization film 49 is not particularly limited, but is preferably 1 mm or less so that the entire thickness of the fuel cell is not excessively increased.

[0056] Examples of the sulfonic acid-based polymer include polymeric materials having alcohol resistance such as methanol. Specifically, a resin mainly composed of perfluorosulfonic acid-based resin is used. The perfluorosulfonic acid-based resin is, for example, a resin having a main chain of fluorine resin and a side chain having a sulfonic acid group. Examples of the resin film that can be used include Naphion (registered trademark) manufactured by DuPont, and Aciplex manufactured by Asahi Kasei.

 In addition to the above, suitable sulfonic acid-based polymers include resins mainly composed of perfluorocarbon-based resins having a carboxyl group. The perfluorocarbon-based resin having a carboxyl group is, for example, a resin having a main chain of fluorine resin and a side chain having a carboxyl group. An example of a strong resin is Flemion manufactured by Asahi Glass Co., Ltd.

 In addition to the above, examples of suitable sulfonic acid-based polymers include resins mainly composed of polysulfone, polyimide, polyetheretherketone, and polyamide. Furthermore, polymeric materials containing silicone, such as silicone rubber, can be mentioned. The resin mainly composed of the above-mentioned predetermined resin is a resin containing 50% by weight or more of the predetermined resin in the entire resin.

[0059] As described above, as a suitable sulfonic acid polymer (as a mixed material of the fuel vaporization film 49), The glued material is a polymer material having resistance to methanol and is non-porous. When such a non-porous material is used as the fuel vaporization film 49, the liquid methanol is vaporized after penetrating into the fuel vaporization film 49. In general, it is possible to obtain a higher permeation capacity than when a porous material is used.

 [0060] On the other hand, the other polymers here have higher mechanical strength than the sulfonic acid-based polymers, and mixing with the sulfonic acid-based polymers reduces the mechanical strength of the sulfonic acid-based polymers. compensate. In addition, other polymers have the property of hardly permeating methanol. In other words, other polymers act to limit the permeation rate of methanol gas, which has a slower methanol permeation rate than sulfonic acid polymers. Suitable other polymers include, for example, vinylidene fluoride resin (PVDF).

 [0061] Furthermore, such a mixed polymer also has the advantage that the permeation rate of methanol in the fuel vaporization membrane 49 can be easily controlled by changing the mixing ratio of the sulfonic acid-based polymer and other polymers. is there. Since sulfonic acid-based polymers represented by perfluorosulfonic acid rosin are expensive, the sulfonic acid-based polymers may be mixed and used at a ratio of 50% by weight or less. !

 [0062] In consideration of the applicable range, in addition to the above-mentioned vinylidene fluoride resin (PVDF), other polymers suitable as a mixed material for the fuel vaporization membrane 49 include polyethylene, polypropylene, polystyrene, polyethylene Examples include terephthalate, polychlorinated butyl, and polyethylene naphtharate. Two or more of these may be mixed.

 [0063] Among the sulfonic acid-based polymers described above, a resin mainly composed of a perfluorosulfonic acid-based resin and a perfluorocarbon-based resin having a carboxyl group include It has a characteristic that the permeation rate of tanol gas (fuel gas) is larger than other materials. Therefore, when a film made of these materials is used as the fuel vaporization film 49, as shown in FIG. 3, a cover made of a metal such as SUS is provided on both sides of the fuel vaporization film 49 also having these material forces. It is also considered effective to arrange this as a solution for controlling the fuel permeation rate.

[0064] However, the sulfonic acid-based polymer has a property of swelling when wetted with an aqueous methanol solution and drying and shrinking when the methanol aqueous solution is cut off. Therefore, figure When the metal is directly sandwiched as shown in FIG. 3, there may be a problem that a fissure 51 as shown in the figure is generated due to a difference in thermal expansion coefficient with the cover 48. When such a phenomenon occurs, the methanol in the fuel leaks to the fuel electrode side as a liquid, leading to a reduction in the amount of power generated.

 [0065] According to the present embodiment, the fuel vaporization film 49 itself has a high mechanical strength. Therefore, the cover 48 is basically unnecessary, and the problem of such a decrease in power generation is avoided. (Ie, while improving durability), low cost can be realized.

 [0066] The effect on durability will be described with reference to FIG. FIG. 4 is a characteristic diagram showing changes in the number of discharges and discharge capacity in Example 1 and Comparative Example.

 In the graph of FIG. 4, the horizontal axis is the number of times of high load discharge, and the vertical axis is the discharge capacity per unit fuel (methanol lcc). One port in the series is the case where the mixed polymer of this example is used, and two series are the case in the comparative example.

 [0068] In the fuel cell according to this example, a mixed polymer (blend ratio 50 wt%) in which PVDF of the same weight was mixed with Nafion manufactured by DuPont was used as the fuel vaporization film. In addition, the fuel cell of the comparative example uses a naphthoion membrane manufactured by DuPont as a fuel vaporization membrane, and uses a naphthoion membrane sandwiched by a cover 48 as shown in FIG. .

 [0069] All other conditions were the same. Specifically, using a fuel cell configured as follows,

2. The current flowing during OV output was measured. The discharge under such conditions was repeated a plurality of times, and the discharge capacity for each number of discharges was calculated.

 'Fuel electrode: platinum ruthenium alloy supported catalyst

 • Air electrode: Platinum supported catalyst

 • Electrolyte: Nafion NF112 (DuPont)

 • Fuel: 100vol% methanol 2.5cc

[0070] For the above discharge electrode area was 10 hours discharge using fuel cells 52cm ^2. The downtime was 10 minutes. During discharge, the current value varies rather than a constant value.

[0071] Specifically, the fuel vaporization film according to this example was manufactured by the following method. [0072] First, using a twin-screw extruder (2D15W type) manufactured by Toyo Seiki, 50 weights of DuPont Nafion (NR50) powder and Kureha PVDF (KF polymer W # 1300) powder % Was mixed. The heating temperature during mixing was 250 ° C and the screw speed was 300 rpm. The heating temperature for mixing is set to a temperature higher than the melting point of the sulfonic acid polymer material and the melting point of the other polymer material.

 [0073] Next, using a film production machine, the mixed polymer which was also injected with the biaxial extruder force was formed into a film with a film thickness of 175 µm.

 Here, when the tensile strength of the produced film (a film in which another polymer was mixed) was measured, the tensile strength was 45 MPa. Since the tensile strength of naphthion (trade name of DuPont) alone is 40MPa, the tensile strength increased by 5MPa by mixing other polymers. As for the tensile strength of the naphthion-only film, naphthion 117 (DuPont product name) was used to verify that the tensile strength was 40 MPa as described above.

 [0075] From the graph of FIG. 4, in the comparative example, the discharge capacity gradually decreases due to the breakage of the fuel vaporization film after the number of discharges exceeds 10 times. This means that a certain discharge capacity is maintained and high durability is ensured.

 [Example 2]

 In this example, a fuel vaporized film made of a mixed polymer was produced by the following method different from the example.

 [0077] First, using a twin-screw extruder (2D15W type) manufactured by Toyo Seiki, powder of Nafion (R-1000) manufactured by DuPont and powder of PVDF (KF polymer W # 1300) manufactured by Kureha were used. 50% by weight was mixed. The heating temperature during mixing was 250 ° C and the screw speed was 300 rpm.

 [0078] Next, using a film production machine, the mixed polymer that was also injected with the biaxial extruder force was formed into a film with a film thickness of 175 µm.

[0079] The process so far differs from Example 1 only in that the DuPont Nafion (NR50) used in Example 1 is replaced with the company's Nafion (R-1000). Nafion (R-1000) has a sulfonic acid group! /, N! /, So to attach a sulfonic acid group.

In the present embodiment, the following steps are further required. [0080] Steps required only for Example 2 below

 Next, the film-like mixed polymer is mixed with 15% KOHZ 35% DMSOZ 50% H 0

 After being immersed in the aqueous solution 2 (500 ml), the mixture was heated and stirred at 80 ° C. for 30 minutes.

[0081] Next, after washing twice for 30 minutes with running water, an aqueous solution of 15% KOH (1000 ml

) For about 1 hour.

[0082] Finally, it was dried at a temperature of 90 ° C for about 2 hours to produce a film-like fuel vaporized film having a thickness of 175 m. In addition, the same effect as Example 1 was confirmed using the produced fuel vaporization film | membrane.

 Industrial applicability

The fuel cell of the present invention can be used as a battery for portable electronic devices such as a mobile phone, a portable information terminal, and a notebook computer.

 Explanation of symbols

[0084] 10 ... Fuel cell

 20 ... Power generation section

 21 ... Air electrode

 22 ... Solid electrolyte layer

 23 ... Fuel electrode

 30 ... Air supply section

 31 ··· Air electrode side housing

 31a… Oxygen supply port

 32, 34 ... Air electrode gas diffusion layer

 33 ... Air current collector

 40 ... Fuel supply section

 41 ... Fuel electrode housing

 42 ... Fuel storage

 43 ... Fuel cartridge

 44 ... Fuel supply port

45 ... Pressure application part ··· Fuel vaporization section

· '· Kano Kuichi

··· Fuel vaporization membrane

· Fuel supply hole ··· Rip

54 ... Fuel gas diffusion layer · Fuel electrode current collector ··· Sealing material

····· Solephonic acid polymer ··· Other polymers

Claims

The scope of the claims  [1] A fuel electrode to which vaporized fuel is supplied to the solid electrolyte layer and an air electrode to which oxygen is supplied to the solid electrolyte layer are provided with a proton conductive solid electrolyte layer interposed therebetween. For fuel cells that use liquid fuel,  The fuel vaporization section that vaporizes the liquid fuel has a fuel vaporization film containing a sulfonic acid-based polymer and another polymer,  The fuel vaporized membrane is interspersed with particles of the other polymer, and the mechanical strength is higher than the mechanical strength of the membrane made of the sulfonic acid polymer.  The fuel cell characterized by the above-mentioned.  [2] A fuel electrode to which vaporized fuel is supplied to the solid electrolyte layer and an air electrode to which oxygen is supplied to the solid electrolyte layer are provided with a proton conductive solid electrolyte layer interposed therebetween. For fuel cells that use liquid fuel,  The fuel vaporization section that vaporizes the liquid fuel has a fuel vaporization film containing a sulfonic acid-based polymer and another polymer having a slower methanol permeation rate than the sulfonic acid-based polymer,  The fuel vaporization film is interspersed with particles of the other polymer.  The fuel cell characterized by the above-mentioned. [3] The mechanical strength of the fuel vaporized membrane is higher than the mechanical strength of the membrane made of the sulfonic acid polymer.  The fuel cell according to claim 2, wherein: [4] The mechanical strength is tensile strength  The fuel cell according to claim 1, wherein: [5] The other polymer particles having an average particle size of micron order are dispersed in the fuel vaporization film.  The fuel cell according to claim 1, wherein: [6] The other polymer is a polymer containing a fluorine atom.  The fuel cell according to claim 1, wherein: [7] The other polymer is vinylidene fluoride resin. The fuel cell according to claim 1, wherein: [8] The other polymer is one or more of polyethylene, polypropylene, polystyrene, polyethylene terephthalate, polychlorinated butyl, and polyethylene naphthalate.  The fuel cell according to claim 1, wherein: [9] The sulfonic acid polymer is a perfluorosulfonic acid resin.  The fuel cell according to claim 1, wherein: [10] In the mixed polymer, the perfluorosulfonic acid-based resin is mixed at a ratio of 50% by weight or less.  The fuel cell according to claim 9, wherein: [11] The fuel vaporized membrane is mixed by a twin-screw extruder at a temperature higher than the melting point of the sulfonic acid polymer and the melting point of the other polymer.  The fuel cell according to claim 1, wherein: