JP2010055954A - Electrode, fuel cell using the same, and electronic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell capable of restraining fuel crossover and restraining generation of overvoltage at an oxygen electrode side, and to provide an electronic device using the same. <P>SOLUTION: A fuel-electrolyte passage 30 is arranged between a fuel electrode 10 and an oxygen electrode 20, and a fuel-electrolyte mixed liquid is circulated in the same passage. The oxygen electrode 20 has a laminated structure of a diffusion layer 22 and a catalyst layer 23 on a current collector 21, and for example, palladium (Pd) and palladium alloy as a selective catalyst which is not reacted with a fuel and reacts with oxygen is included in the catalyst layer 23. The fuel is not oxidized in the oxygen electrode 20, and deterioration of characteristics caused by the fuel crossover can be restrained. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electrode used as an oxygen electrode such as a direct methanol fuel cell (DMFC) in which methanol is directly supplied to a fuel electrode to cause a reaction, a fuel cell using the electrode, and a fuel cell using the fuel cell. It is related with the provided electronic equipment.

  There are an energy density and an output density as indices indicating the characteristics of the battery. The energy density is an energy storage amount per unit mass of the battery, and the output density is an output amount per unit mass of the battery. Lithium ion secondary batteries have two characteristics of relatively high energy density and extremely high power density, and since they are highly complete, they are widely used as power sources for mobile devices. However, in recent years, power consumption of mobile devices tends to increase as performance increases, and further improvements in energy density and output density are required for lithium ion secondary batteries.

  Solutions include changing the electrode materials that make up the positive and negative electrodes, improving the application method of the electrode materials, and improving the encapsulation method of the electrode materials, and research to improve the energy density of lithium-ion secondary batteries has been conducted. It has been broken. However, the hurdles for practical use are still high. In addition, unless the constituent materials used in current lithium ion secondary batteries are changed, it is difficult to expect significant improvement in energy density.

  For this reason, the development of a battery with higher energy density to replace the lithium ion secondary battery is urgently needed, and the fuel cell is regarded as a promising candidate.

  The fuel cell has a configuration in which an electrolyte is disposed between an anode (fuel electrode) and a cathode (oxygen electrode). Fuel is supplied to the fuel electrode, and air or oxygen is supplied to the oxygen electrode. As a result, an oxidation-reduction reaction occurs in which the fuel is oxidized by oxygen at the fuel electrode and the oxygen electrode, and a part of the chemical energy of the fuel is converted into electric energy and extracted.

  Various types of fuel cells have already been proposed or prototyped, and some have been put into practical use. Depending on the electrolyte used, these fuel cells may be alkaline electrolyte fuel cells (AFC), phosphoric acid fuel cells (PAFC), molten carbonate fuel cells (MCFC), or molten carbonate fuel cells (MCFC). Cell), solid oxide fuel cell (SOFC), polymer electrolyte fuel cell (PEFC), and the like. Among these, the PEFC can be operated at a temperature lower than that of other types, for example, about 30 ° C to 130 ° C.

  As the fuel for the fuel cell, various combustible substances such as hydrogen and methanol can be used. However, gaseous fuel such as hydrogen is not suitable for miniaturization because a storage cylinder or the like is required. On the other hand, liquid fuel such as methanol is advantageous in that it is easy to store. In particular, the DMFC does not require a reformer for taking out hydrogen from the fuel, and has an advantage that the configuration is simplified and the miniaturization is easy.

  In DMFC, fuel methanol is usually supplied to a fuel electrode as a low-concentration or high-concentration aqueous solution or in a pure methanol gas state, and is oxidized to carbon dioxide in a catalyst layer of the fuel electrode. Protons generated at this time move to the oxygen electrode through the electrolyte membrane separating the fuel electrode and the oxygen electrode, and react with oxygen at the oxygen electrode to generate water. The reaction that occurs in the fuel electrode, oxygen electrode, and DMFC as a whole is represented by Chemical Formula 1.

(Chemical formula 1)
Fuel electrode: CH ₃ OH + H ₂ O → CO ₂ + 6e ⁻ + 6H ⁺
Oxygen ^{_{electrode: (3/2) O 2 + 6e}} - + 6H + → 3H 2 O
Entire DMFC: CH ₃ OH + (3/2) O ₂ → CO ₂ + 2H ₂ O

  The energy density of methanol, which is a fuel of DMFC, is theoretically 4.8 kW / L, which is more than 10 times the energy density of a general lithium ion secondary battery. That is, a fuel cell using methanol as a fuel has many possibilities of surpassing the energy density of a lithium ion secondary battery. From the above, DMFC is most likely to be used as an energy source for mobile devices and electric vehicles among various fuel cells.

  However, the DMFC has a problem that, although the theoretical voltage is 1.23V, the output voltage when actually generating power is reduced to about 0.6V or less. The cause of the decrease in the output voltage is a voltage drop caused by the internal resistance of the DMFC. In the DMFC, the resistance caused by the reaction that occurs at both electrodes, the resistance that accompanies the movement of the substance, and the proton that occurs when the proton moves through the electrolyte membrane There are internal resistances such as resistance and contact resistance. The energy that can actually be extracted as electrical energy from the oxidation of methanol is represented by the product of the output voltage during power generation and the amount of electricity flowing through the circuit. The energy that can be produced is reduced accordingly. Note that the amount of electricity that can be extracted into the circuit by the oxidation of methanol is proportional to the amount of methanol in the DMFC if the total amount of methanol is oxidized at the fuel electrode according to Chemical Formula 1.

  Also, DMFC has a problem of methanol crossover (fuel crossover). Methanol crossover is an electricity that transports hydrated methanol by the phenomenon that methanol diffuses and moves due to the difference in methanol concentration between the fuel electrode side and oxygen electrode side, and the movement of water caused by the movement of protons. This is a phenomenon in which methanol permeates the electrolyte membrane from the fuel electrode side and reaches the oxygen electrode side due to two mechanisms of the permeation phenomenon.

  When methanol crossover occurs, the permeated methanol is oxidized at the catalyst layer of the oxygen electrode. The methanol oxidation reaction on the oxygen electrode side is the same as the above-described oxidation reaction on the fuel electrode side, but causes a decrease in the output voltage of the DMFC. Further, since methanol is not used for power generation on the fuel electrode side and is wasted on the oxygen electrode side, the amount of electricity that can be taken out by the circuit is reduced accordingly. Further, since the catalyst layer of the oxygen electrode is not a platinum (Pt) -ruthenium (Ru) alloy catalyst but a platinum (Pt) catalyst, carbon monoxide (CO) is easily adsorbed on the catalyst surface, and the catalyst is poisoned. There are also inconveniences such as

  As described above, the DMFC has two problems, that is, a voltage drop caused by internal resistance and methanol crossover, and a waste of fuel due to the methanol crossover, which cause the power generation efficiency of the DMFC to be reduced. Therefore, in order to increase the power generation efficiency of the DMFC, research and development for improving the characteristics of the materials constituting the DMFC and research and development for optimizing the operating conditions of the DMFC are being conducted vigorously.

  In the research to improve the characteristics of the material constituting the DMFC, there are things related to the electrolyte membrane and the catalyst on the fuel electrode side. Currently, polyperfluoroalkylsulfonic acid resin membranes (“Nafion (registered trademark)” manufactured by DuPont) are generally used for electrolyte membranes, but higher proton conductivity and higher methanol permeation prevention Fluorine polymer membranes, hydrocarbon polymer electrolyte membranes, hydrogel-based electrolyte membranes, and the like have been studied as having high performance. With respect to the catalyst on the fuel electrode side, research and development of a catalyst having higher activity than the platinum (Pt) -ruthenium (Ru) alloy catalyst that is generally used at present has been conducted.

  Such improvement in the characteristics of the constituent materials of the fuel cell is appropriate as a means for improving the power generation efficiency of the fuel cell. However, the present situation is that an optimum electrolyte membrane has not been found as well as an optimum catalyst that can overcome the above two problems is not found.

On the other hand, Patent Document 1 discloses a technique using a liquid electrolyte (electrolytic solution) instead of the electrolyte membrane. In some cases, the electrolyte solution is stationary between the oxygen electrode and the fuel electrode, but flows through the flow path provided between the oxygen electrode and the fuel electrode. It may be returned and circulated.
JP 59-191265 A

  However, in the electrolyte noncirculation type fuel cell described in Patent Document 1 or the electrolyte circulation type fuel cell having the same structure as this, a fuel crossover occurs and an overvoltage is generated on the oxygen electrode side. This is because the fluid containing fuel passes through the fuel electrode without being reacted, and further flows during power generation at a certain flow rate or passes through a stationary liquid electrolyte and reaches the oxygen electrode, and the fuel is oxidized. Because. In order to suppress the fuel crossover, it is sufficient that almost all of the fuel reacts when passing through the fuel electrode, and if the fuel concentration is optimized, it can be significantly suppressed.

  Although the above structure is very excellent as a crossover suppressing structure, it is a structure that completely separates the electrolyte and the liquid containing the fuel, so that the electrolyte flow path is always between the oxygen electrode and the fuel electrode. It is necessary to form a fuel flow path on the fuel electrode surface not facing the oxygen electrode. Therefore, when producing the above fuel cell, two flow paths are required to separate the fuel and the electrolyte, and when the fuel cell is generated, both the electrolyte and the fuel are circulated. In this case, since fine control is required for both liquids, the structure and control are slightly complicated.

  The simplest structure of a fuel cell using a liquid electrolyte is a structure in which a “fuel / electrolyte mixed solution” containing dissolved fuel is supplied between a fuel electrode and an oxygen electrode. That is, it is sufficient to form one flow path, and the structure is very simple.

  However, this method also has a fatal problem. Since the liquid mixture containing the fuel dissolved in the electrolytic solution is supplied between the fuel electrode and the oxygen electrode, the fuel is directly supplied to the oxygen electrode side. Therefore, fuel crossover is always occurring, and overvoltage is generated on the oxygen electrode side. Needless to say, this is a serious problem in a fuel cell using a normal platinum-based catalyst on the oxygen electrode side.

  The present invention has been made in view of such problems, and a first object of the invention is to provide a fuel cell capable of suppressing the influence of fuel crossover and preventing characteristic deterioration due to overvoltage on the oxygen electrode side, and the fuel cell. It is to provide an electronic device used.

  A second object of the present invention is to provide an electrode that can be suitably used as an oxygen electrode of the fuel cell.

  A fuel cell according to the present invention is provided between a fuel electrode and an oxygen electrode, a fuel electrode, an oxygen electrode that is disposed opposite to the fuel electrode, and includes a selective catalyst that does not react with fuel but reacts with oxygen. And at least an electrolyte flow path for circulating the electrolyte.

  The electrode according to the present invention is used as an oxygen electrode of the fuel cell according to the present invention, and has a catalyst layer containing a selective catalyst that does not react with fuel on a current collector.

  An electronic apparatus according to the present invention includes the fuel cell according to the present invention.

  In the fuel cell of the present invention, since the oxygen electrode contains a selective catalyst that does not react with fuel but reacts with oxygen, only the reaction between oxygen and the selective catalyst occurs at the oxygen electrode, and the fuel is supplied to the oxygen electrode. Even if contacted, the fuel and the selective catalyst do not react. Therefore, overvoltage on the oxygen electrode side is suppressed.

  According to the fuel cell of the present invention or the electrode of the present invention, since the oxygen electrode includes a selective catalyst that does not react with fuel but reacts with oxygen, the fuel crossover is suppressed, and the overvoltage on the oxygen electrode side is reduced. It is possible to suppress the characteristic deterioration due to.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a cross-sectional structure of a fuel cell 110 according to an embodiment of the present invention. This fuel cell 110 is a so-called direct methanol flow based fuel cell (DMFFC), and has a configuration in which a fuel electrode (anode) 10 and an oxygen electrode (cathode) 20 are arranged to face each other. ing. Between the fuel electrode 10 and the oxygen electrode 20, there is provided a fuel / electrolyte flow path 30 through which the fuel / electrolyte mixed liquid (fluid F1) flows.

  The fuel electrode 10 is obtained by laminating a diffusion layer 12 and a catalyst layer 13 in this order on a current collector 11. On the other hand, the oxygen electrode 20 has a configuration in which a diffusion layer 22 and a catalyst layer 23 are laminated on a current collector 21 in this order. The catalyst layer 13 and the catalyst layer 23 face the fuel / electrolyte flow path 30.

  The current collector 11 is made of, for example, a porous material or a plate-like member having electrical conductivity, specifically, a titanium (Ti) mesh or a titanium plate. Similarly, the current collector 21 is made of, for example, a titanium mesh or a titanium plate.

The diffusion layers 12 and 22 are made of, for example, carbon cloth, carbon paper, or a carbon sheet. These diffusion layers 12 and 22 are preferably subjected to water repellent treatment with polytetrafluoroethylene (PTFE) or the like. However, the diffusion layers 12 and 22 are not necessarily provided, and the catalyst layer may be formed directly on the current collector.

  The catalyst layer 13 on the fuel electrode 10 side has a property of oxidizing a fuel as a catalyst, for example, a metal such as palladium (Pd), platinum (Pt), iridium (Ir), rhodium (Rh), and ruthenium (Ru). It is composed of a simple substance or an alloy, an organic complex, an enzyme or the like.

  On the other hand, the catalyst layer 23 on the oxygen electrode 20 side includes, as a catalyst, a selective catalyst that does not react with fuel but reacts with oxygen. Thereby, in this fuel cell 110, fuel crossover can be suppressed and characteristic deterioration due to overvoltage on the oxygen electrode side can be suppressed.

  The selective catalyst is preferably, for example, palladium (Pd) or a palladium-based alloy. Specifically, as the selective catalyst, a binary system such as palladium iron (PdFe), palladium nickel (PdNi), palladium cobalt (PdCo), palladium chromium (PdCr), palladium gold (PdAu), palladium cobalt gold ( Examples thereof include ternary catalysts such as PdCoAu) and palladium iron gold (PdFeAu), and ruthenium selenium (RuSe) which is a ruthenium alloy. In addition, the catalyst layer 23 includes an organic complex, an enzyme, and the like.

  In addition to the catalyst, the catalyst layers 13 and 23 may contain a proton conductor and a binder. Examples of the proton conductor include the above-described polyperfluoroalkylsulfonic acid resin (“Nafion (registered trademark)” manufactured by DuPont) or other resins having proton conductivity. The binder is added to maintain the strength and flexibility of the catalyst layers 13 and 23, and examples thereof include resins such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF).

  Exterior members 14 and 24 are provided outside the fuel electrode 10 and the oxygen electrode 20, respectively. The exterior members 14 and 24 have, for example, a thickness of 1 mm and are made of a generally available material such as a titanium (Ti) plate, but the material is not particularly limited. In addition, if the thickness of the exterior members 14 and 24 is thin, the thinner one is desirable.

  The fuel / electrolyte channel 30 is formed, for example, by forming a fine channel by processing a resin sheet, and is bonded to the surface of the fuel electrode 10 facing the oxygen electrode 20. The fuel / electrolyte channel 30 is supplied with a fluid F1 containing a fuel and an electrolyte, for example, a methanol-sulfuric acid mixed solution, via a fuel / electrolyte inlet 14A and a fuel / electrolyte outlet 14B provided in the exterior member 14. It has become. The number and shape of the flow paths are not limited and may be, for example, a snake shape or a parallel type. Further, the width, height, and length of the flow path are not particularly limited, but a smaller one is desirable. In the fuel / electrolyte channel 30, the fuel and the electrolyte may be mixed and may be circulated, or the fuel and the electrolyte may be circulated in a separated state.

  An air flow path 40 for supplying air or oxygen is provided on the opposite side (outside) of the oxygen electrode 20 from the fuel / electrolyte flow path 30. Air is supplied to the air flow path 40 by natural ventilation or a forced supply method such as a fan, a pump, and a blower through an air inlet 24A and an air outlet 24B provided in the exterior member 24. Yes.

  The fuel cell 110 can be manufactured, for example, as follows.

  First, as a catalyst, for example, an alloy containing platinum (Pt) and ruthenium (Ru) in a predetermined ratio, and a dispersion solution of a polyperfluoroalkylsulfonic acid resin (“Nafion (registered trademark)” manufactured by DuPont). The catalyst layer 13 of the fuel electrode 10 is formed by mixing at a predetermined ratio. This catalyst layer 13 is thermocompression bonded to the diffusion layer 12 made of the above-described material. Subsequently, the diffusion layer 12 and the catalyst layer 13 are thermocompression bonded to one surface of the current collector 11 made of the above-described material using a hot-melt adhesive or an adhesive resin sheet to form the fuel electrode 10. . Note that the catalyst layer 13 may be directly formed on the current collector 11 without forming the diffusion layer 12 as described above.

  Moreover, as a catalyst, a selective catalyst such as palladium iron black or palladium iron-supporting carbon and a dispersion solution of polyperfluoroalkylsulfonic acid resin (“Nafion (registered trademark)” manufactured by DuPont) is mixed in a predetermined ratio. Then, the catalyst layer 23 of the oxygen electrode 20 is formed. This catalyst layer 23 is thermocompression bonded to the diffusion layer 22 made of the above-described material. Subsequently, the diffusion layer 22 and the catalyst layer 23 are thermocompression bonded to the current collector 21 made of the above-described material using a hot-melt adhesive or an adhesive resin sheet to form the oxygen electrode 20.

  Next, an adhesive resin sheet is prepared, and a flow path is formed in the resin sheet to form the fuel / electrolyte flow path 30. Further, the exterior member 14 made of the above-described material is provided with a fuel / electrolyte inlet 14A and a fuel / electrolyte outlet 14B made of, for example, a resin joint, and the exterior member 24 has an air inlet 24A made of, for example, a resin joint, and An air outlet 24B is provided.

  Subsequently, the fuel / electrolyte channel 30 is thermocompression bonded to the surface of the fuel electrode 10 facing the oxygen electrode 20.

  Thereafter, the oxygen electrode 20 is bonded to the thermocompression-bonded fuel / electrolyte flow path 30 and stored in the exterior members 14 and 24. Thereby, the fuel cell 110 shown in FIG. 1 is completed.

  Next, the operation of the fuel cell 110 will be described.

  In the fuel cell 110, when fuel and electrolyte are supplied to the fuel electrode 10 through the fuel / electrolyte channel 30, protons and electrons are generated by the reaction. Protons move to the oxygen electrode 20 through the fuel / electrolyte channel 30 and react with electrons and oxygen to generate water. The reaction that occurs in the fuel electrode 10, the oxygen electrode 20, and the fuel cell 110 as a whole is represented by Chemical Formula 2 below. Thereby, a part of the chemical energy of methanol, which is the fuel, is converted into electric energy and taken out as electric power. Carbon dioxide generated at the fuel electrode 10 and water generated at the oxygen electrode 20 flow out to the fuel / electrolyte flow path 30 and are removed.

(Chemical formula 2)
Fuel electrode _{10: CH 3 OH + H 2} O → CO 2 + 6e - + 6H +
Oxygen electrode 20: (3/2) O ₂ + 6e ⁻ + 6H ⁺ → 3H ₂ O
Entire fuel cell 110: CH ₃ OH + (3/2) O ₂ → CO ₂ + 2H ₂ O

  Here, since the catalyst layer 23 of the oxygen electrode 20 includes a selective catalyst that does not react with the fuel but reacts with oxygen, the fuel is not oxidized at the oxygen electrode 20. That is, in the oxygen electrode 20, the oxidation reaction of methanol that occurs at the fuel electrode 10 shown in Chemical Formula 2 does not proceed. Therefore, characteristic deterioration due to fuel crossover is suppressed, and it is possible to realize the fuel cell 110 that is stable and highly efficient in the long term.

  On the other hand, if a platinum-based catalyst having very excellent fuel oxidation ability and oxygen reduction ability is used for the oxygen electrode, as described above, the reaction that occurs at the fuel electrode also occurs on the oxygen electrode, resulting in overvoltage. As a result, a fuel cell characteristic deterioration phenomenon occurs (fuel crossover).

FIG. 2A shows current-voltage characteristics when palladium iron (PdFe) as a selective catalyst is used for the oxygen electrode 20 of the fuel cell 110, and FIG. 2B shows current-power characteristics. It is what. 2A and 2B show a comparison between the case where the fuel concentration of the fuel / electrolyte mixture is set to 0.5M and the case where the fuel concentration is set to 1.0M. The concentration of sulfuric acid as an electrolyte is 0.5M.

  As can be seen from FIGS. 2A and 2B, when palladium iron (PdFe), which is a selective catalyst, is used for the oxygen electrode 20, both current-voltage characteristics and current-power characteristics are obtained. Very good results were obtained. When platinum was used as the catalyst, immediately after the fuel / electrolyte mixture was supplied, power generation stopped due to the influence of fuel crossover, making measurement impossible.

  Further, when the fuel concentration of the fuel / electrolyte mixed solution is compared with the case where the fuel concentration is 0.5M and 1.0M, the characteristics are improved when the fuel concentration is increased to 1.0M. From this, it can be seen that even when the fuel concentration is increased, the catalytic activity of the fuel electrode is improved without being affected by the fuel crossover generated in the oxygen electrode 20.

  FIG. 3 shows the results of detecting the methanol contained in the air discharged from the outlet 24B of the air flow path 40 and examining the relationship between the concentration and the generated current. Here, the selectivity of methanol oxidation when palladium iron (PdFe) is used for the oxygen electrode 20 is compared with the case where platinum (Pt) is used for the oxygen electrode 20. The fuel concentration of the fuel / electrolyte mixture is 0.5M methanol.

  From FIG. 3, it can be seen that when palladium iron (PdFe) is used as the oxygen electrode 20 at the outlet 24B of the air flow path 40, a higher methanol concentration is detected than when platinum (Pt) is used. This is considered to be because, when palladium iron (PdFe) was used for the oxygen electrode 20, the methanol oxidation reaction did not occur, so that methanol was not consumed by the oxygen electrode 20 but was detected at the air flow path outlet 24. . In addition, the difference between the palladium iron (PdFe) curve and the platinum (Pt) curve indicates the difference in overvoltage generated at the oxygen electrode 20 due to methanol crossover, and the generation of this overvoltage significantly deteriorates the characteristics of the fuel cell. Cause it.

  That is, it was found that if the oxygen electrode 20 contains palladium iron (PdFe), which is a selective catalyst, overvoltage in the oxygen electrode 20 can be suppressed and characteristic deterioration can be suppressed. In addition, although the result of PdFe was shown here, since it has the same characteristic if it is any of the selective catalyst mentioned above, the same result can be obtained.

  As described above, in the fuel cell 110 according to the present embodiment, the oxygen electrode 20 includes a selective catalyst that does not react with fuel but reacts with oxygen. Therefore, a fatal problem occurs when a platinum catalyst is used. It is possible to suppress deterioration in characteristics due to fuel crossover, deterioration in catalyst durability, and reduction in catalyst capacity due to poisoning of the reaction surface of the catalyst. Accordingly, it can be suitably used for multifunctional and high-performance electronic devices with large power consumption. In particular, it is extremely suitable when the fuel / electrolyte mixture is directly supplied between the oxygen electrode 20 and the fuel electrode 10.

  In particular, the fuel / electrolyte channel 30 allows the fuel and the electrolyte to circulate through the same channel, so that the fuel and the electrolyte can be supplied through a single channel, and the fuel and the electrolyte are separated from each other. Compared with the case where it circulates in a flow path, it becomes a simple structure and it becomes easy to realize thickness reduction. Furthermore, an electrolyte membrane is not required, power generation can be performed without being affected by temperature and humidity, and ion conductivity (proton conductivity) can be increased as compared with the case where an electrolyte membrane is used. In addition, there is no risk of deterioration of the electrolyte membrane or a decrease in proton conductivity due to drying of the electrolyte membrane, and problems such as flooding and moisture management in the oxygen electrode can be solved.

  Next, an application example of the fuel cell 110 will be described.

(Application example)
FIG. 4 shows a schematic configuration of an electronic device using the fuel cell 110. The electronic device is, for example, a mobile device such as a mobile phone or a PDA (Personal Digital Assistant), a notebook PC (Personal Computer), and the like. The fuel cell system 1 and the fuel cell system 1 generate power. And an external circuit (load) 2 driven by the electric energy generated.

  The fuel cell system 1 includes, for example, a fuel cell 110, a measuring unit 120 that measures the operating state of the fuel cell 110, and a control unit 130 that determines the operating conditions of the fuel cell 110 based on the measurement result of the measuring unit 120. It has. The fuel cell system 1 also includes a fuel / electrolyte supply unit 140 that supplies the fuel cell 110 with a fluid F1 containing fuel and electrolyte, and a fuel that supplies only the fuel F2 such as methanol to the fuel / electrolyte storage unit 141. And a supply unit 150. The fuel / electrolyte flow path 30 in the fuel cell 110 is connected to the fuel / electrolyte supply unit 140 via a fuel / electrolyte inlet 14A and a fuel / electrolyte outlet 14B provided in the exterior member 14, so that the fuel / electrolyte is supplied. The fluid F1 is supplied from the supply unit 140.

  The measuring unit 120 measures the operating voltage and operating current of the fuel cell 110. For example, the measuring unit 120 measures the operating voltage of the fuel cell 110, the current measuring circuit 122 that measures the operating current, and the And a communication line 123 for sending the measured result to the control unit 130.

  The control unit 130 controls the fuel / electrolyte supply parameter and the fuel supply parameter as operating conditions of the fuel cell 110 based on the measurement result of the measurement unit 120. For example, the calculation unit 131, the storage (memory) unit 132, a communication unit 133 and a communication line 134. Here, the fuel / electrolyte supply parameter includes, for example, the supply flow rate of the fluid F1 containing the fuel / electrolyte. The fuel supply parameter includes, for example, a supply flow rate and a supply amount of the fuel F2, and may include a supply concentration as necessary. The control unit 130 can be configured by a microcomputer, for example.

  The calculation unit 131 calculates the output of the fuel cell 110 from the measurement result obtained by the measurement unit 120, and sets the fuel / electrolyte supply parameter and the fuel supply parameter. Specifically, the calculation unit 131 averages the anode potential, the cathode potential, the output voltage, and the output current sampled at regular intervals from various measurement results input to the storage unit 132, and calculates the average anode potential, average cathode potential, The average output voltage and the average output current are calculated and input to the storage unit 132, and various average values stored in the storage unit 132 are compared with each other to determine the fuel / electrolyte supply parameter and the fuel supply parameter. ing.

  The storage unit 132 stores various measurement values sent from the measurement unit 120, various average values calculated by the calculation unit 131, and the like.

  The communication unit 133 receives a measurement result from the measurement unit 120 via the communication line 123 and inputs the measurement result to the storage unit 132, and the fuel / electrolyte supply unit 140 and the fuel supply unit 150 via the communication line 134. And a function of outputting signals for setting the supply parameter and the fuel supply parameter.

  The fuel / electrolyte supply unit 140 includes a fuel / electrolyte storage unit 141, a fuel / electrolyte supply adjustment unit 142, and a fuel / electrolyte supply line 143. The fuel / electrolyte storage unit 141 stores the fluid F1 and is configured by, for example, a tank or a cartridge. The fuel / electrolyte supply adjustment unit 142 adjusts the supply flow rate of the fluid F1. The fuel / electrolyte supply adjusting unit 142 is not particularly limited as long as it can be driven by a signal from the control unit 130. For example, the fuel / electrolyte supply adjusting unit 142 may be a valve driven by a motor or a piezoelectric element, or an electromagnetic pump. It is preferable to be configured.

  The fuel supply unit 150 includes a fuel storage unit 151, a fuel supply adjustment unit 152, and a fuel supply line 153. The fuel storage unit 151 stores only the fuel F2 such as methanol, and is configured by, for example, a tank or a cartridge. The fuel supply adjustment unit 152 adjusts the supply flow rate and supply amount of the fuel F2. The fuel supply adjustment unit 152 is not particularly limited as long as it can be driven by a signal from the control unit 130. For example, the fuel supply adjustment unit 152 includes a valve driven by a motor or a piezoelectric element, or an electromagnetic pump. It is preferable. The fuel supply unit 150 may include a concentration adjusting unit (not shown) that adjusts the supply concentration of the fuel F2. The concentration adjusting unit can be omitted when pure (99.9%) methanol is used as the fuel F2, and the size can be further reduced.

  The fuel cell system 1 can be manufactured as follows. For example, the fuel cell 110 is incorporated into a system having the measurement unit 120, the control unit 130, the fuel / electrolyte supply unit 140, and the fuel supply unit 150 having the above-described configuration, and the fuel inlet 14A, the fuel outlet 14B, and the fuel supply unit 150 are included. Are connected by a fuel supply line 153 made of, for example, a silicone tube, and the fuel / electrolyte inlet 14A, the fuel / electrolyte outlet 14B, and the fuel / electrolyte supply unit 140 are connected by a fuel / electrolyte supply line 143 made of, for example, a silicone tube. . Thereby, the fuel cell system 1 shown in FIG. 4 is completed.

  In such a fuel cell system 1, when the fluid F1 containing fuel and electrolyte is supplied from the fuel / electrolyte supply unit 140 to the fuel cell 110, electric power is taken out from the fuel cell 110 and the external circuit 2 is driven. During the operation of the fuel cell 110, the operating voltage and operating current of the fuel cell 110 are measured by the measuring unit 120, and based on the measurement results, the control unit 130 determines the fuel / electrolysis described above as the operating condition of the fuel cell 110. Liquid supply parameters and fuel supply parameters are controlled. The measurement by the measurement unit 120 and the parameter control by the control unit 130 are frequently repeated, and the supply state of the fluid F1 and the fuel F2 is optimized following the characteristic variation of the fuel cell 110.

  Since the fuel cell system 1 includes the fuel cell 110, high output can be realized with a simple configuration with high flexibility that can be incorporated into a large-sized device from a mobile device. Therefore, it can be suitably used for a multifunctional and high-performance electronic device that is thin and consumes a large amount of power.

  While the present invention has been described with reference to the embodiment, the present invention is not limited to the above embodiment, and various modifications can be made. For example, in the above-described embodiment, the configuration of the fuel electrode 10, the oxygen electrode 20, the fuel / electrolyte channel 30 and the air channel 40 has been specifically described. However, the configuration may be made of other structures or other materials. Also good. For example, the fuel / electrolyte channel 30 is formed by processing a resin sheet as described in the above embodiment to form a channel, or a porous body, for example, a sheet such as a nonwoven fabric. May be soaked.

  For example, in the above-described embodiment, the fuel / electrolyte channel 30 is described as an example of supplying a fluid in which fuel and electrolyte are mixed between the fuel electrode 10 and the oxygen electrode 20. However, the present invention is not limited to this. For example, a fuel supply channel for distributing fuel to the fuel electrode 10 side and an electrolyte channel for distributing electrolyte to the oxygen electrode 20 side may be provided separately. Good. Alternatively, in this case, an electrolyte membrane having ion conductivity may be provided on the oxygen electrode 20 side instead of a flow path through which the electrolyte solution is circulated. However, as described in the above embodiment, when the fuel and the electrolyte are circulated through the same flow path, the increase in thickness can be more effectively suppressed.

Further, for example, the fluid F1 containing the fuel and the electrolyte described in the above embodiment is not particularly limited as long as it has proton (H ⁺ ) conductivity. For example, in addition to sulfuric acid, phosphoric acid or ions Liquid. Furthermore, the fuel F2 described in the embodiment may be other alcohols such as ethanol and dimethyl ether or sugar fuel in addition to methanol.

  In addition, although the case where air is supplied to the oxygen electrode 20 has been described in the above embodiment, oxygen or a gas containing oxygen may be supplied instead of air.

  Furthermore, the material and thickness of each component described in the above embodiment or the operating conditions of the fuel cell 110 are not limited, and may be other materials and thicknesses, or may be other operating conditions. Good.

  In addition, in the above embodiment, the direct methanol fuel cell has been described as an example of the fuel cell. However, the present invention is not limited to this, and a fuel cell using a substance other than liquid fuel such as hydrogen as a fuel, for example, PEFC (Polymer Electrolyte Fuel Cell (solid polymer fuel cell), alkaline fuel cell, or enzyme battery using sugar fuel such as glucose is also applicable.

  Furthermore, in the above-described embodiments and examples, the single cell type fuel cell has been described. However, the present invention can also be applied to a stacked type in which a plurality of cells are stacked.

1 is a cross-sectional view illustrating a schematic configuration of a fuel cell according to an embodiment of the present invention. It is a figure for demonstrating the characteristic of the fuel cell shown in FIG. It is a figure for demonstrating the characteristic of the fuel cell shown in FIG. It is a figure showing the schematic structure of the electronic device provided with the fuel cell shown in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Fuel cell system, 2 ... External circuit (load), 10 ... Fuel electrode, 11, 21 ... Current collector, 12, 22 ... Diffusion layer, 13, 23 ... Catalyst layer, 20 ... Oxygen electrode, 14, 24 ... Exterior member, 30 ... Fuel / electrolyte flow path, 40 ... Air flow path, 110 ... Fuel cell, 120 ... Measuring part, 123 ... Communication line, 130 ... Control part, 131 ... Calculation part, 132 ... Storage part, 133 ... Communication unit 134 ... Communication line 140 ... Fuel / electrolyte supply unit 141 ... Fuel / electrolyte storage unit 142 ... Fuel / electrolyte supply adjustment unit 143 ... Fuel / electrolyte supply line 150 ... Fuel supply unit 151 ... A fuel storage unit, 152... A fuel supply adjustment unit, 153... A fuel supply line.

Claims (6)

A fuel electrode;
An oxygen electrode that is disposed opposite the fuel electrode and includes a selective catalyst that does not react with fuel but reacts with oxygen;
A fuel cell comprising: an electrolyte flow path provided between the fuel electrode and the oxygen electrode and allowing at least an electrolyte to flow therethrough.   The fuel cell according to claim 1, wherein the oxygen electrode has a catalyst layer containing the selective catalyst on a current collector, and the catalyst layer faces the electrolyte flow path.   The fuel cell according to claim 1, wherein the electrolyte channel is a fuel / electrolyte channel that allows fuel to flow along with the electrolyte.   The fuel cell according to any one of claims 1 to 3, wherein the selective catalyst is palladium or a palladium alloy. On the current collector, a catalyst layer containing a selective catalyst that does not react with fuel but reacts with oxygen,
An electrode used as the oxygen electrode of a fuel cell having an electrolyte flow path for allowing at least an electrolyte to flow between the fuel electrode and the oxygen electrode. Comprising a fuel cell having an electrolyte flow path for flowing at least an electrolyte between the fuel electrode and the oxygen electrode;
The electronic device in which the oxygen electrode has a catalyst layer including a selective catalyst that does not react with fuel but reacts with oxygen on the current collector.

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