JP2008097986A - Direct methanol type fuel battery system and portable electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a direct methanol type fuel battery system of supplying methanol as gas, with the use of solid methanol extremely safe in a fuel cartridge state, and solving such problems as liquid leak, crossover, and degradation of outputs in the case of use of liquid fuel as a system. <P>SOLUTION: The direct methanol type fuel battery system is provided with a fuel container part 3 containing solid methanol solidifying methanol, a fuel battery cell 5, and a carrier gas circulation means 1. The fuel container part 3 is provided with a carrier gas supply channel 2 communicated with the carrier gas circulation means 1, and a fuel gas circulation channel 4 communicated with a fuel electrode side of the fuel battery cell 5. The fuel battery cell 5 is provided with a circulation flow channel 9 communicated with the fuel electrode side as well as the carrier gas circulation means 1, so that, when carrier gas is supplied from the carrier gas circulation means 1 to the fuel container part 5 through the carrier gas supply channel 2, fuel gas containing methanol flows back from the circulation flow channel 9 to the carrier gas circulation means 1, after the fuel gas containing methanol is supplied to the fuel electrode. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a direct methanol fuel cell system using solid methanol as a fuel, and more particularly to a direct methanol fuel cell system suitable for small portable electronic devices.

  A solid polymer electrolyte fuel cell has a solid electrolyte membrane such as a perfluorosulfonic acid membrane as an electrolyte, and a fuel electrode (anode) and an oxidant electrode (cathode) are joined to both sides of the membrane, and hydrogen is connected to the anode. It is a device that generates electricity through an electrochemical reaction by supplying oxygen to methanol and cathode. Among these, a solid polymer electrolyte fuel cell using methanol as a fuel is called a “direct methanol fuel cell (DMFC)”, and power is generated by the following reaction formula.

Anode: CH ₃ OH + H ₂ O → 6H ⁺ + CO ₂ + 6e ⁻ ... [1]
Cathode: 3/2 O ₂ + 6H ⁺ + 6e ⁻ → 3H ₂ O [2]
In order to cause this reaction, both electrodes are composed of a mixture of carbon fine particles carrying a catalyst material and a solid polymer electrolyte.

  In such a direct methanol fuel cell, the methanol supplied to the anode passes through the pores in the electrode and reaches the catalyst. The methanol is decomposed by this catalyst, and the electrons in the reaction of the above reaction formula [1]. And hydrogen ions are produced. The hydrogen ions reach the cathode through the electrolyte in the anode and the solid electrolyte membrane between the two electrodes, react with oxygen supplied to the cathode and electrons flowing from the external circuit, and water as shown in the above reaction formula [2]. Produce. On the other hand, electrons emitted from methanol are led to the external circuit through the catalyst carrier in the anode, and flow into the cathode from the external circuit. As a result, in the external circuit, electrons flow from the anode to the cathode, and electric power is taken out.

  The direct methanol fuel cell using methanol as a fuel is useful as a small power source for portable electronic devices because it has a low operating temperature and does not require a large auxiliary machine. Development has been activated as a next-generation power source.

  On the other hand, since methanol used for fuel is liquid, it easily leaks, and there are concerns about the flammability and toxicity of methanol itself, and measures for safe use have become issues. In addition, when liquid methanol is supplied to the fuel electrode of the fuel cell, carbon dioxide gas is generated at the fuel electrode as described above, but the reaction at the fuel electrode is poor because of the poor release of carbon dioxide gas from liquid methanol. There is a problem that it becomes an obstructive factor and easily reduces output. Further, in order to maintain the contact state between the liquid and the fuel electrode, there is a problem that the direction of the fuel cell is limited.

  Furthermore, the disadvantages of using liquid fuel are the degradation of fuel cell performance due to the impurities dissolved in the liquid fuel being supplied to the fuel cell, and methanol, which is a liquid fuel component, permeates the electrolyte membrane of the fuel cell. And a crossover phenomenon that reaches the air electrode.

Therefore, in order to solve such problems such as the safety of methanol, the present applicant has variously reported about "solid methanol fuel" which solidifies methanol by forming a molecular compound, makes it difficult to leak and greatly reduces flammability. Proposed (see Patent Documents 1 to 3). When this solid methanol comes into contact with water, the methanol in the solid is released to the water side. The aqueous methanol solution thus produced can be used directly as a fuel for a methanol fuel cell.
JP 2006-040629 A JP 2005-325254 A International Publication No. 2005/0624210 Pamphlet

  However, the method of use proposed in Patent Documents 1 to 3 is to extract methanol by bringing solid methanol into contact with water to produce an aqueous methanol solution, which is supplied to the fuel cell. . Therefore, the fuel cell system has problems such as leakage of methanol aqueous solution and crossover as in liquid fuel. In addition, this water supply system requires water supply means such as a water tank and a pump, but it is preferable that the apparatus has a simple device structure that does not require them in order to be applied to a portable electronic device or the like. Therefore, a direct methanol fuel cell that supplies methanol as a gas has been desired.

  The present invention has been made in view of the above problems, and uses liquid methanol that is very safe in the state of the fuel cartridge, and also uses liquid fuel as a system, such as liquid leakage, crossover, output reduction, etc. An object of the present invention is to provide a direct methanol fuel cell system in which methanol is solved as a gas and is supplied as a gas. Another object of the present invention is to provide a portable electronic device using the direct methanol fuel cell system.

  In order to solve the above-mentioned problems, the present invention includes a fuel storage unit that stores solid methanol obtained by solidifying methanol, a fuel cell, and carrier gas circulation means, and the fuel storage unit includes the carrier. A carrier gas supply path communicating with the gas circulation means and a fuel gas flow passage communicating with the fuel electrode side of the fuel cell are provided, and the fuel cell communicates with the fuel electrode side with the fuel cell side. A fuel gas containing methanol vaporized from the solid methanol is provided when a carrier gas is provided from the carrier gas circulating means to the fuel storage portion through the carrier gas supply path. Is supplied to the fuel electrode of the fuel cell and then recirculates from the circulation channel to the carrier gas circulation means. Providing (claim 1).

  According to the above invention (Invention 1), when the carrier gas is supplied to the fuel storage portion by the carrier gas circulation means such as a pump, in the case of solid methanol, the methanol is loosened by the intermolecular force such as the inclusion phenomenon inside the material. The fuel gas containing the gas is gradually vaporized and supplied to the fuel electrode of the fuel cell, and the vaporized methanol is decomposed on the fuel electrode catalyst. Power is generated. In order to generate power in a fuel cell, it is necessary to supply an equimolar amount of water to the fuel electrode, but the reaction proceeds by using the water originally retained in the electrolyte membrane at the start of power generation. However, as the reaction proceeds, water generated at the air electrode reversely osmosis through the electrolyte membrane and is supplied to the fuel electrode, so that power generation occurs without supplying water.

  Then, by continuing the supply of the carrier gas, the fuel electrode is replenished with methanol and power generation is continued. On the other hand, excess methanol is recirculated from the circulation flow path to the carrier gas circulation means and reused. . Thus, since excess methanol is not supplied to a fuel electrode, it can be set as the direct methanol fuel cell system by which problems, such as crossover and a liquid leak, were solved. In addition, since the carrier gas is circulated and used, it is not necessary to separately provide a gas cylinder or the like, and the methanol contained in the solid methanol can be effectively used.

  In the said invention (invention 1), it is preferable that the said fuel accommodating part is a detachable cartridge (invention 2). According to this invention (invention 2), when the amount of methanol contained in solid methanol decreases, the methanol concentration in the fuel gas decreases, and the output of the fuel cell decreases, the cartridge is replaced, It can be used again in good condition.

  In the said invention (invention 1,2), it is preferable that the carrier gas supplied to the fuel electrode of the said fuel cell substantially does not contain oxygen (invention 3). According to this invention (invention 3), it is possible to prevent the generation of harmful substances such as formaldehyde, formic acid and methyl formate due to the oxidation of methanol, and also prevent the generation of heat and the consumption of methanol due to the oxidation of methanol. Can do.

  In the said invention (Invention 1-3), it is preferable that the said solid methanol is what solidified methanol aqueous solution (Invention 4). Moreover, in the said invention (Invention 1-3), it is preferable that the said fuel accommodating part contains a water-containing solid material with the said solid methanol (Invention 5). Furthermore, in the said invention (Invention 1-3), it is preferable to provide the water replenishment container containing a water-containing solid material between the said fuel accommodating part and the said fuel battery cell (Invention 6).

  As described above, the reaction proceeds by using the water originally retained in the electrolyte membrane at the start of power generation, and as the reaction proceeds, the water generated at the air electrode reversely permeates the electrolyte membrane and supplies it to the fuel electrode. Therefore, power generation occurs even if water is not supplied, but when water consumption is high, that is, when the output of the fuel cell is increased, if the operation is continued in such a state, the electrolyte membrane is removed from the air electrode. Moisture is insufficient with only the moisture that is reverse osmosis and supplied to the fuel electrode or the humidity in the air, and the output may decrease over time. This is considered to be caused by the fact that when the water in the fuel electrode is insufficient, not only the water necessary for the reaction cannot be supplied, but also the electrical conductivity of the electrolyte membrane decreases.

  Therefore, in the above inventions (inventions 4 to 6), water and methanol are also solid, so that methanol and water vaporize without the presence of water as a liquid in the system, so that the electrolyte Moisture required for wetting and reaction can be supplied, and stable power generation can be performed.

  In the said invention (invention 1-6), it is preferable that the said fuel gas flow path is formed in the branched form in the said fuel electrode (invention 7).

  Normally, in a direct methanol fuel cell of liquid fuel supply type, the separator that becomes the fuel flow path at the fuel electrode is a single meandering flow path, but when this is applied to vaporized methanol gas, Since the concentration of methanol gas in the fuel gas decreases from upstream to downstream of the separator, the electromotive force decreases due to Nernstross.

  Therefore, according to the above invention (invention 7), the fuel gas flow passage is formed in a branched shape at the fuel electrode, thereby reducing the difference in concentration of methanol gas in the fuel gas, thereby reducing the electromotive force. It is possible to suppress.

  Moreover, this invention provides the portable electronic device characterized by including the direct methanol fuel cell system of the said invention (Invention 1-7) (Invention 8). According to this invention (Claim 8), problems such as crossover and liquid leakage are improved, efficient power generation is possible, and stable operation is possible by using a compact direct methanol fuel cell system. Portable electronic devices.

  ADVANTAGE OF THE INVENTION According to this invention, problems, such as crossover and a liquid leak, are improved, problems, such as a power fall, can be solved, and the direct methanol type fuel cell system which can generate electric power efficiently can be provided. In addition, since it is not necessary to provide a water supply means, a carrier gas cylinder, or the like, the direct methanol fuel cell system can also be made compact.

Hereinafter, a direct methanol fuel cell system according to an embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a flowchart showing a direct methanol fuel cell system according to this embodiment, and FIG. 2 is a cross-sectional view showing a solid methanol fuel cartridge in the direct methanol fuel cell system according to this embodiment.

  As shown in FIGS. 1 and 2, the direct methanol fuel cell system according to the present embodiment includes a pump 1 serving as a carrier gas circulation means that takes in normal air (air) as a carrier gas, and a solid methanol fuel storage unit. The solid methanol fuel cartridge 3 and the fuel cell 5 are provided. The exhaust side of the pump 1 and the solid methanol fuel cartridge 3 communicate with each other through the carrier gas supply path 2, and the solid methanol fuel cartridge 3. And the fuel cell 5 communicate with each other through a fuel gas flow passage 4.

  In such a direct methanol fuel cell system, the solid methanol fuel cartridge 3 is provided with a partition wall 3B so as to form a bent channel in the box-shaped casing 3A as shown in FIG. Filled with solid methanol S. Then, one side (the upper side in the figure) partitioned by the partition wall 3B is connected to the carrier gas supply path 2, and the other side (the lower side in the figure) is connected to the fuel gas flow path 4, so that the carrier gas is The solid methanol S passes while making sufficient contact.

  The fuel cell 5 includes a fuel electrode 6, a solid polymer electrolyte membrane 7, and an air electrode 8, and the fuel electrode 6 is connected to the fuel gas flow path 4 and the circulation flow path 9 connected to the intake side of the pump 1. Are sealed in a cover 5A communicating with each other, and the air electrode 8 is open to the atmosphere. The circulation channel 9 is provided with a pressure regulating valve (not shown).

  Further, as shown in FIG. 3, a meandering separator 11 is incorporated in the cover 5A, one end of the separator 11 is connected to the fuel gas flow passage 4, and the other end is connected to the circulation passage 9. The fuel gas passes along the separator 11.

In the direct methanol fuel cell system as described above, normal air (air) is used as a carrier gas in the present embodiment. However, the present invention is not limited to this, and nitrogen gas (N ₂ ), an inert gas, or the like is supplied. May be. Note that when air is used as a carrier gas, oxygen is contained, so that oxidation of methanol generates harmful substances such as formaldehyde, formic acid, and methyl formate in addition to water. However, in this embodiment, since the carrier gas is recycled, oxygen is consumed immediately, and this oxidation reaction does not occur only in the initial stage. Therefore, the harmful substance has substantially no problem, and moisture generated in the initial state is supplied to the fuel electrode.

  Further, as the solid methanol S, a methanol molecular compound including a clathrate compound of methanol, methanol solidified with a polymer or gelled with dibenzylidene-D-sorbitol, magnesium aluminate metasilicate, etc. Substances that contain methanol and show a solid state, such as those made solid by holding methanol by adsorption or the like on inorganic materials, and those in which the vaporization temperature of methanol is adjusted by coating them. Anything can be used.

  A molecular compound is a compound in which two or more kinds of compounds that can exist stably alone are bonded by a relatively weak interaction other than a covalent bond, such as a hydrogen bond or van der Waals force. Hydrates, solvates, addition compounds, inclusion compounds and the like.

  Such a molecular compound can be formed by a contact reaction between a compound that forms the molecular compound and methanol, can convert methanol into a solid compound, and can store methanol in a relatively lightweight and stable manner. Can do. In particular, an inclusion compound in which methanol is included by a reaction between a host compound and methanol is preferable.

  As solid methanol, the thing of various forms, such as a sheet form, block shape (block shape), and a granular form, can be used. Among these, the particulate form is preferable. By using particulate methanol as the solid methanol and reducing the particle size, the vaporization rate of methanol can be increased and the generated methanol vapor can be easily moved.

  The particle size of the solid methanol is preferably in the range of 1 μm to 10 mm, particularly 100 μm to 5 mm in view of handling properties, filling properties, gas mobility and the like.

  Such solid methanol is preferably obtained by incorporating 1 to 3 parts by mass of methanol with respect to 1 part by mass of the base material.

  Such solid methanol does not have to be 100% pure methanol, but water added to methanol to obtain a methanol aqueous solution with a desired concentration. Also good.

  In this embodiment, the fuel cartridge 3 may contain a water-containing solid material together with the solid methanol S. The water-containing solid material may be any material that can be constrained to such an extent that water does not leak out as a liquid, such as inorganic porous materials such as magnesium aluminate metasilicate, organic porous materials, fibrous materials, and water-absorbing polymer materials. Etc. can be applied. Specifically, silica-based and titania-based inorganic porous materials, activated carbon, porous glass material, glass fiber, fiber materials such as general cloth and paper, cellulose fiber, polyamide-based water absorbent resin, etc. It is not limited to these. Moreover, you may use what adjusted the vaporization temperature of water by coating a water-containing solid material.

  Such a water-containing solid material is preferably obtained by incorporating 1 to 3 parts by mass of water with respect to 1 part by mass of the base material.

The operation of the direct methanol fuel cell system having such a configuration will be described.
In FIG. 1, when air is introduced into the circulation flow path and air is circulated by the pump 1, the air flows into the solid methanol fuel cartridge 3 through the carrier gas supply path 2.

  The solid methanol S in the fuel cartridge 3 does not vaporize at a stroke because the methanol is gently restrained by the intermolecular force including the inclusion phenomenon inside the material, but gradually vaporizes. The methanol molecules gradually vaporized from the surface of the solid methanol S are mixed with air and supplied as fuel gas from the fuel gas flow passage 4 to the fuel electrode 6 of the fuel cell 5, as shown in FIG. It reacts at the fuel electrode 6 through the separator 11.

As a result, power generation is performed according to the following reaction formula.
Anode: CH ₃ OH + H ₂ O → 6H ⁺ + CO ₂ + 6e ⁻ ... [1]
Cathode: 3/2 O ₂ + 6H ⁺ + 6e ⁻ → 3H ₂ O [2]

  At this time, the methanol concentration in the vicinity of the fuel electrode 6 is considerably dilute compared with the method of directly supplying liquid methanol (aqueous solution), but not all of the methanol in the fuel electrode 6 reacts even in the liquid supply method. Only partly decomposed due to the limit of activity. Moreover, the more methanol is, the more methanol is crossed over to the air electrode 8 side.

  Therefore, a high concentration of methanol in the fuel electrode 6 is not necessarily a merit, and even with methanol having a concentration just vaporized from solid methanol through the carrier gas, an output almost equivalent to that of the liquid supply method can be obtained. It is done.

  And while methanol is decomposed | disassembled and reduced by the fuel electrode 6, since the methanol gas from solid methanol is also supplied by continuing supply of the carrier gas by the pump 1, the said electric power generation reaction will continue. Become.

  At this time, in the reaction formula [1], equimolar water with methanol is required. However, as described above, water is generated by the initial oxidation reaction of methanol by using air as a carrier gas. The reaction is started by the moisture due to the oxidation of methanol and the moisture originally held by the solid polymer electrolyte membrane 7. Then, as the reaction proceeds, as shown in the reaction formula [2], water generated at the air electrode 8 reversely permeates the solid polymer electrolyte membrane 7 and is supplied to the fuel electrode 6, thereby continuing the power generation reaction. To do. However, in order to reliably perform initial power generation, water may be included in the fuel electrode 6 in advance.

  In addition, when there is little moisture in the air which is carrier gas and there exists a possibility that a water | moisture content may run short only with the water | moisture content produced by reaction of a cathode, it is preferable to use the water-containing solid material mentioned above together. As a result, the water vaporized from the water-containing solid material is supplied to the fuel electrode 6 together with methanol and the carrier gas. However, in order to reliably perform initial power generation, water may be included in the fuel electrode 6 in advance.

  The reaction between methanol and water produces carbon dioxide gas that is equimolar with methanol, and this carbon dioxide gas is circulated from the circulation channel 9 to the pump 1. Further, methanol (gas) remaining without reacting at the fuel electrode 6 is also circulated from the circulation flow path 9 to the pump 1. Thereby, since the methanol contained in the solid methanol S does not diffuse into the external environment, the methanol can be effectively used and the life of the fuel cartridge 3 can be extended. Furthermore, it is not necessary to prepare a carrier gas cylinder or the like separately.

  In addition, when the inside of the path exceeds a predetermined pressure due to carbon dioxide gas or the like generated by the anode reaction, an appropriate amount of carrier gas can be released from a pressure regulating valve (not shown) provided in the circulation channel 9. Good.

  Then, the solid methanol S is supplied with the methanol contained in the fuel cell along with the power generation, so that the methanol content is reduced. Then, the power generation can be continued by replacing the fuel cartridge 3 together.

  As mentioned above, although this invention has been demonstrated based on embodiment, this invention is not limited to the said embodiment, A various deformation | transformation implementation is possible.

  For example, in the above embodiment, the separator 11 of the fuel electrode 6 has a meandering shape as shown in FIG. 3, but in such a separator 11, the upstream (fuel gas flow path 4) side to the downstream (circulation flow path 9). Since the concentration of methanol gas in the fuel gas decreases with the reaction at the fuel electrode 6, the electromotive force decreases due to Nernstross. Therefore, the fuel from the upstream side of the separator 11 to the downstream side is formed by forming the separators 11A in parallel as shown in FIG. 4 or by forming the separators 11B in a grid shape as shown in FIG. Since the difference in concentration of methanol gas in the gas can be reduced, it is preferable to suppress the decrease in electromotive force. In addition, the separator 11 can be made into various branched shapes, such as not only this but forming radially.

  Further, when solid methanol and a water-containing solid material are used in combination, there is no need to mix the solid methanol and the water-containing solid material into the fuel cartridge 3 as in the above embodiment, and the solid methanol fuel cartridge 3 Apart from this, a cartridge (water replenishing container) of water-containing solid material may be provided between the fuel cartridge 3 and the fuel cell 5, that is, in the fuel gas flow path 4.

  The direct methanol fuel cell system according to the present embodiment as described above does not have a liquid inside the system, can be made compact, and as long as the solid methanol has a predetermined amount of methanol, there is no decrease in output, etc. It is particularly suitable as a power source for portable electronic devices that are required to be downsized.

  The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to the following examples as long as the gist of the present invention is not exceeded.

[Example 1]
[Fuel battery cell]
The following fuel cell was used for the test.
MEA: MEA for DMFC manufactured by Chemix
・ Electrolyte membrane: Nafion117 (DuPont, film thickness 50μm)
・ Anode (fuel electrode) catalyst; Pt-Ru / C
・ Cathode (air electrode) catalyst; Pt / C
-Effective membrane area: 40 x 40 mm
Current collecting material: SUS mesh (Au plating)
Fuel electrode: sealed structure Air electrode: open structure

[Preparation of film-forming solid methanol]
After blending hydroxypropyl cellulose (2 g) and methanol (300 g) with magnesium aluminate metasilicate powder (100 g), the mixture was granulated into spherical particles having a diameter of about 3 mm using a granulator to obtain solid methanol particles. .

  After introducing the solid methanol particles into the coating apparatus, a 0.5% methanol aqueous solution of ethyl cellulose, which is a film forming material, is sprayed at a flow rate of 10 mL / min for 5 minutes and dried to form a film of ethyl cellulose having a thickness of about 30 μm on the surface. The film-forming solid methanol particles were formed. The methanol content of the film-forming solid methanol particles was about 65%.

[Direct methanol fuel cell system]
2 g of the film-forming solid methanol particles were filled in the cartridge 3 shown in FIG. 2 having a size of 40 × 40 × 10 (mm) and mounted on the system shown in FIG. 1 to prepare a system. At this time, as the fuel electrode 6 of the fuel cell 5, pure water was previously stretched and wetted, pure water was removed before the test, and water droplets were removed with a nitrogen gas flow. The carrier gas had a flow rate of 80 mL / min, and the separator 11 of the fuel electrode 6 had the shape shown in FIG.

[Comparative Example 1]
A direct methanol fuel cell system (Comparative Example 1) was produced in the same manner as in Example 1 except that a 3% aqueous methanol solution was supplied to the fuel electrode 6 of the fuel cell 5 without using a carrier gas.

[Power generation test]
With respect to the direct methanol fuel cell systems of Example 1 and Comparative Example 1, a current was passed by an electronic load device, and the characteristics of the fuel cell were measured. The horizontal axis is the load current density (mA / cm ² , the load current divided by the effective membrane area of the MEA), and the cell output density (mW / cm ² , the load current density and the voltage value between the fuel electrode and the air electrode) FIG. 6 shows a graph in which the product of (V) is the vertical axis.

As is clear from FIG. 6, in the direct methanol fuel cell system of Example 1, the cell voltage during measurement was stable, and the maximum output was about 7 mW / cm ² . Furthermore, there was almost no decrease in output even when the carrier gas was circulated in that state for 2 hours.

In contrast, in the direct methanol fuel cell system of Comparative Example 1 to which the aqueous methanol solution was supplied, the cell voltage during the measurement was stable, but the maximum output was as low as about 6.5 mW / cm ^2. A decrease in output was also observed when running for hours. This is considered to be due to a decrease in reactivity at the fuel electrode 6 due to carbon dioxide gas.

[Example 2]
A direct methanol fuel cell system was prepared in the same manner as in Example 1, except that a film-forming solid methanol was prepared using an aqueous methanol solution (concentration: 70% by mass), and the methanol content was 40% and the water content was 20%. (Example 2) was produced.

  The direct methanol fuel cell system of Example 2 was subjected to a power generation test similar to that of Example 1, and the characteristics of the fuel cell were measured. As a result, the stability over time was better than that of Example 1. This is considered to be because moisture is supplied to the fuel electrode 6 together with methanol.

[Example 3]
In Example 1, except that 3 g of the film-forming solid methanol and 2 g of the water-containing solid material (water-containing neucillin, water content 75%) 2 g produced in the same manner as the film-forming solid methanol were used to fill the fuel cartridge 3. In the same manner, a direct methanol fuel cell system (Example 3) was produced.

  The direct methanol fuel cell system of Example 3 was subjected to a power generation test similar to that of Example 1, and the characteristics of the fuel cell were measured. As a result, the stability over time was better than that of Example 1. This is considered to be because moisture is supplied to the fuel electrode 6 together with methanol.

[Example 4]
A direct methanol fuel cell system (Example 4) was produced in the same manner as in Example 1 except that the separator 11 of the fuel electrode 6 of the fuel cell 5 shown in FIG. 4 was used.

  The direct methanol fuel cell system of Example 4 was subjected to a power generation test similar to that of Example 1, and the characteristics of the fuel cell were measured. As a result, the output did not decrease for a longer time than Example 1. This is thought to be due to the improvement of Nernstross.

[Example 5]
A direct methanol fuel cell system (Example 5) was produced in the same manner as in Example 1 except that the separator 11 of the fuel electrode 6 of the fuel cell 5 shown in FIG. 5 was used.

  The direct methanol fuel cell system of Example 4 was subjected to a power generation test similar to that of Example 1, and the characteristics of the fuel cell were measured. As a result, the output did not decrease for a longer time than Example 1. This is thought to be due to the improvement of Nernstross.

It is a flow figure showing a direct methanol type fuel cell system concerning one embodiment of the present invention. It is sectional drawing which shows the fuel cartridge in the direct methanol fuel cell system which concerns on one Embodiment of this invention. 1 is a plan view schematically showing a first example of a fuel electrode and a separator in a direct methanol fuel cell system according to an embodiment of the present invention. It is a top view which shows roughly the 2nd example of the fuel electrode and separator in the direct methanol fuel cell system which concerns on one Embodiment of this invention. It is a top view which shows roughly the 3rd example of the fuel electrode and separator in the direct methanol fuel cell system which concerns on one Embodiment of this invention. It is a graph which shows the relationship between the load current density in the direct methanol fuel cell system of Example 1 and the comparative example 1, and the output density of a cell.

Explanation of symbols

1 ... Pump (carrier gas circulation means)
2 ... Carrier gas supply path 3 ... Solid methanol fuel cartridge (fuel storage part)
4 ... Fuel gas flow passage 5 ... Fuel cell 6 ... Fuel electrode 7 ... Solid polymer electrolyte membrane 8 ... Air electrode 9 ... Circulation channel S ... Solid methanol

Claims (8)

A fuel storage section for storing solid methanol obtained by solidifying methanol;
A fuel cell;
A carrier gas circulation means,
The fuel accommodating portion is provided with a carrier gas supply path communicating with the carrier gas circulation means and a fuel gas flow path communicating with the fuel electrode side of the fuel cell,
The fuel battery cell is provided with a circulation flow path that communicates with the fuel electrode side and communicates with the carrier gas circulation means.
When the carrier gas is supplied from the carrier gas circulation means to the fuel storage unit through the carrier gas supply path, the fuel gas containing methanol vaporized from the solid methanol is supplied to the fuel electrode of the fuel cell, A fuel cell system, wherein the fuel cell system recirculates from the circulation channel to the carrier gas circulation means.   2. The direct methanol fuel cell system according to claim 1, wherein the fuel storage unit is a detachable cartridge.   The direct methanol fuel cell system according to claim 1 or 2, wherein the carrier gas supplied to the fuel electrode of the fuel cell does not substantially contain oxygen.   The direct methanol fuel cell system according to any one of claims 1 to 3, wherein the solid methanol is a solidified methanol aqueous solution.   The direct methanol fuel cell system according to any one of claims 1 to 3, wherein the fuel storage unit contains a water-containing solid material together with the solid methanol.   The direct methanol fuel cell system according to any one of claims 1 to 3, further comprising a water replenishment container containing a water-containing solid material between the fuel storage unit and the fuel battery cell.   The direct methanol fuel cell system according to any one of claims 1 to 6, wherein the fuel gas flow passage is formed in a branched shape in the fuel electrode.   A portable electronic device comprising the direct methanol fuel cell system according to claim 1.

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