JP4585804B2 - Liquid fuel cell - Google Patents

Description

  The present invention relates to a liquid fuel cell, and more particularly to a technique for controlling a cell temperature.

  In recent years, as a power source for portable electronic devices that support the information society, the efficiency of a single power generation device is high, and therefore, expectations for fuel cells are increasing. A fuel cell is a mechanism for generating electricity through this reaction by electrochemically oxidizing and reducing fuel at an anode and air at a cathode.

  Among various types of fuel cells, a polymer electrolyte fuel cell (hereinafter referred to as “PEFC”) using a solid polymer ion exchange membrane as an electrolyte has a thin electrolyte membrane and reaction. Since the temperature is 100 ° C. or lower, which is a relatively low temperature compared to other fuel cells, large-scale auxiliary equipment is not required, and thus downsizing is possible. In recent years, it is expected as a next-generation power source for automobiles and households, and those using hydrogen as a fuel are already being put into practical use in automobiles. In this case, as a means for containing fuel (hydrogen) High-pressure cylinders are mainly used.

  On the other hand, a direct methanol fuel cell (hereinafter referred to as “DMFC”), which generates electricity by directly extracting protons from methanol, does not require a reformer and is more in comparison to gas fuel. Since liquid methanol with a high volumetric energy density is used, the fuel container can be made smaller than a high-pressure gas cylinder, so that it can be applied to power supplies for small devices, especially for secondary battery replacement for portable devices. Attention has been gathered.

  However, a DMFC using methanol as a fuel has a lower power output than a PEFC using hydrogen as a fuel because the overvoltage of methanol oxidation on the anode side is very large. Therefore, in order to use a fuel cell as a power source for portable equipment, it is essential to improve the power generation efficiency. In general, it is known that as the temperature rises, the catalytic activity of the anode and cathode electrodes increases and the polarization of both electrodes decreases, and raising the cell temperature is effective for improving power generation efficiency. It is one of the means.

  Further, in order to be able to be used as a power source for portable devices, the same level of usability as a conventional battery is required. That is, it is required that the device can be used immediately after the power is turned on, and that it can cope with frequent power on / off operations. However, in general, when the fuel cell is restarted after being unused for a long time, at the beginning of the supply of fuel, the cell reaction layer in the fuel cell is at room temperature, so that the rated power cannot be obtained immediately. Problems arise.

Accordingly, as a conventional technique, in order to start the fuel cell early, when the temperature of the fuel cell is detected and determined to be equal to or lower than a predetermined temperature, the output terminals of the positive electrode and the negative electrode of the fuel cell are low impedance. A circuit configuration is disclosed in which a quasi-short-circuit state is established via a load of the current so that a larger current than normal flows in the fuel cell (see, for example, Patent Document 1).
JP 2000-30719 A

  As described above, when the fuel cell is restarted after being unused for a long period of time, at the beginning of the supply of fuel, the cell reaction layer in the fuel cell is at room temperature, so the rated power cannot be obtained immediately. The problem arises. In the prior art described in Patent Document 1, a battery temperature control circuit is disclosed in order to solve the above problem. However, since the energy owned by the battery is converted into electrical energy and then converted into thermal energy, there is a problem that energy loss occurs in the process. In addition, it is necessary to install a temperature control circuit outside, and the system becomes large and heavy, so it is not suitable for portable use.

  The present invention has been made in view of such circumstances, and provides a liquid fuel cell capable of improving the startup characteristics at startup with a simple configuration.

  The liquid fuel cell according to the present invention includes a first cell and a second cell in which a fuel electrode and an air electrode are disposed with an electrolyte membrane interposed therebetween, and the second cell is disposed in thermal contact with the first cell. The liquid permeability of the electrolyte membrane is higher than that of the first cell.

  The liquid fuel supplied to the fuel electrode is usually decomposed by a catalyst provided in the fuel electrode to generate protons, which move through the electrolyte membrane to the air electrode, and are generated during proton generation. Moves through the external circuit to the air electrode, and protons, electrons, and oxygen in the air react at the air electrode to generate electricity (battery operation). However, a part of the liquid fuel is not decomposed at the fuel electrode, passes through the electrolyte membrane as it is, moves to the air electrode, reacts with oxygen in the air at the air electrode, and is oxidized to generate heat (crossover operation). . In this crossover operation, since liquid fuel is not used for power generation, this operation has led to a decrease in fuel utilization efficiency and has been conventionally considered undesirable.

  However, since the crossover operation occurs even when the cell is at a low temperature and there is no process for extracting electrons from the liquid fuel via an external circuit, this operation generates more heat in the cell than in the case of battery operation.

  The inventor of the present invention can obtain a liquid fuel cell that can improve start-up characteristics at start-up with a simple configuration by actively utilizing a crossover operation that has been considered to be undesirable in the past. As a result, the present invention has been completed.

  According to the present invention, since the liquid permeability of the electrolyte membrane of the second cell is higher than that of the first cell, the liquid fuel easily moves from the fuel electrode to the air electrode in the second cell, and a crossover operation is likely to occur. For this reason, the second cell easily generates heat due to the crossover operation even at a low temperature. Since the second cell is in thermal contact with the first cell, the first cell is heated by the heat generated in the second cell. For this reason, the temperature of both the first and second cells rises, and the startup characteristics at startup are improved.

  The second cell is not only a fuel cell but also a heater for heating the first cell. For this reason, it is not necessary to separately provide a heater, and the entire liquid fuel cell can be reduced in size. Further, since the second cell directly converts the fuel into heat energy, the energy conversion loss can be reduced. In addition, since the same type of material as that used for the battery reaction is used as the combustion energy source (ie, the same fuel can be used to generate power and generate heat), the system is simpler than using other materials. In addition, fuel can be easily replenished, and from this point, the entire fuel cell can be downsized.

  The liquid fuel cell according to the present invention includes a first cell and a second cell in which a fuel electrode and an air electrode are disposed with an electrolyte membrane interposed therebetween, and the second cell is disposed in thermal contact with the first cell. The liquid permeability of the electrolyte membrane is higher than that of the first cell.

The present invention can be mainly implemented in the following two embodiments.
1. First Embodiment A liquid fuel cell according to a first embodiment of the present invention is characterized in that a first cell and a second cell are connected in series.

  In the first embodiment, at least one of a plurality of cells connected in series has a function as a battery and a function as a heater for heating another cell based on the principle described above. . Therefore, in this embodiment, the heater can be incorporated into the fuel cell without adding a new member.

  Here, the specific structure of the liquid fuel cell of this embodiment is illustrated using FIG. FIG. 1 is an exemplification, and the scope of the present embodiment is not limited to the structure of FIG. The liquid fuel cell of this embodiment includes a first cell 1 and a second cell 11, which are electrically connected to each other via a flow path plate 6. That is, the first cell 1 and the second cell 11 are connected in series. The first cell 1 has a structure in which the fuel electrode 3 and the air electrode 4 are arranged with the electrolyte membrane 2 interposed therebetween, and the second cell 11 has the fuel electrode 13 and the air electrode 14 with the electrolyte membrane 12 interposed therebetween. Each has a distributed structure. The fuel electrodes 3 and 13 include fuel electrode current collectors 3a and 13a and fuel electrode catalyst layers 3b and 13b, respectively. The air electrodes 4 and 14 include air electrode current collectors 4a and 14a and air electrode catalyst layers 4b and 14b, respectively. The electrolyte films 2 and 12 are made of a polymer film, an inorganic film, an organic-inorganic hybrid film, or the like. The air electrode catalyst layer 14b of the second cell 11 preferably includes a CO poisoning resistant catalyst. As will be described later, in the second cell 11, a crossover operation is likely to occur. In the crossover operation, CO is generated and the air electrode catalyst layer 14b is likely to be poisoned. Therefore, it is preferable that the air electrode catalyst layer 14b of the second cell 11 is resistant to CO poisoning and protected from CO. Specifically, an alloy such as Pt / Ru, Pt / Os, Pt / Ir, Pt / Pd, Pt / Rh, Pt / Sn is used as the CO poisoning resistant catalyst.

  Liquid fuel is supplied to the fuel electrodes 3 and 13 through the liquid fuel flow paths 5a and 6a formed on one side of the flow path plates 5 and 6. The liquid fuel flows into the liquid fuel flow paths 5a and 6a from the liquid fuel inlets 5b and 6b, and is discharged from the liquid fuel discharge ports 5c and 6c. Liquid fuel is circulated by a liquid feed pump. As a liquid fuel supply method, in addition to the method shown in FIG. 1, a method in which the liquid fuel in the fuel storage tank is naturally dropped, a method in which fuel is drawn from the fuel storage tank using the capillary force of the porous body, a liquid fuel The method of vaporizing and supplying with steam etc. is mentioned. As the liquid fuel, an organic solution containing hydrogen atoms such as methanol, DME (dimethyl ether) or formic acid, or a mixed liquid fuel with a gas can be used.

  Air is supplied to the air electrodes 4 and 14 through the air flow paths 6d and 7d formed on one side of the flow path plates 6 and 7. Air is supplied by a blower fan or the like. As the air supply method, in addition to the fuel electrode flow paths 5a and 6a, the air flow paths 6d and 7d are formed by a single flow path having an inlet and an outlet, as shown in FIG. The method of supplying air with a pump is mentioned.

  The second cell 11 is disposed in thermal contact with the first cell 1. That is, the flow path plate 6 between the first cell 1 and the second cell 11 is formed of a material having high thermal conductivity (for example, carbon). The liquid permeability of the electrolyte membrane 12 in the second cell 11 is higher than that of the electrolyte membrane 2 in the first cell 1. In order to increase the liquid permeability of the electrolyte membrane, the film thickness may be reduced. Therefore, the second cell 11 preferably has an electrolyte membrane 12 having a thickness smaller than that of the first cell 1. The second cell 11 may have an electrolyte membrane 12 made of a material different from that of the first cell 1. The liquid permeability of the electrolyte membrane may differ depending on the material of the membrane. By using different materials for the electrolyte membrane of the first cell 1 and the second cell 11, the liquid permeability of the electrolyte membrane 12 of the second cell 11 can be changed. The rate can be higher than that of the first cell 1.

Here, the operation of the present embodiment will be described.
Part of the liquid fuel supplied to the fuel electrode 13 of the second cell 11 is decomposed by the fuel electrode catalyst layer 13b to generate protons, contributing to power generation (battery operation). On the other hand, the remainder of the fuel that has not been decomposed by the catalyst layer 13b reaches the air electrode 14 through the electrolyte membrane 12 having a high liquid permeability, where it is oxidized by oxygen in the air supplied to the air electrode 14 and is heated. Occurs (crossover operation). That is, the second cell 11 performs both power generation and heat generation. The heat generated in the second cell 11 is conducted to the first cell 1 through the flow path plate 6. For this reason, the temperature of both the 1st cell 1 and the 2nd cell 11 rises.

  Immediately after startup, the temperature of the first cell 1 and the second cell 11 is usually low and the liquid fuel is difficult to be decomposed, so the power generation efficiency is poor. In this embodiment, the second cell 11 generates heat and quickly The temperature of the first cell 1 and the second cell 11 is increased. Therefore, according to the present embodiment, a fuel cell with good start-up characteristics can be obtained without adding new parts.

  In FIG. 1, only the first and second cells are illustrated, but a configuration in which more cells are stacked and electrically connected in series may be employed. And it becomes possible to ensure a required voltage and electric power by pressing and fixing each member with the support base material 8 from the outermost part of those cells. When stacking multiple cells, a fuel flow path is formed on one side of each flow path plate, and an air flow path is formed on the other side, thereby reducing the number of parts and obtaining good electrical conduction. Can do.

2. Second Embodiment A liquid fuel cell according to a second embodiment of the present invention is characterized in that the second cell is electrically separated from the first cell.

  Also in this embodiment, the second cell is similar to the first embodiment in that it generates both power and heat. Therefore, the description of the electrolyte membrane or the catalyst layer in the first embodiment is applicable to the second embodiment as long as it does not contradict the purpose.

  In the present embodiment, the first and second cells are not connected in series, and the second cell is electrically separated from the first cell. For this reason, the heat generated in the second cell is supplied to the first cell, but the electricity generated in the second cell is used independently of the first cell.

  In the second embodiment, the liquid fuel flow rate that varies the flow rate of the liquid fuel supplied to the fuel electrode of the second cell in conjunction with the temperature of the first cell so that the flow rate becomes zero at the first threshold temperature. It is preferable to further include a control unit. The first threshold temperature is usually set lower than a limit temperature that causes deterioration of the first cell. The amount of heat generated in the second cell can be controlled by changing the flow rate of the liquid fuel supplied to the fuel electrode of the second cell in conjunction with the temperature of the first cell. The temperature can be controlled. The liquid fuel flow rate control unit can be configured using, for example, a valve that is linked to temperature fluctuations.

  Further, it is preferable to further include an air flow rate control unit that varies the flow rate of the air supplied to the air electrode of the second cell in conjunction with the temperature of the first cell so that the flow rate becomes zero at the first threshold temperature. . By changing the flow rate of air to the second cell, the amount of heat generated in the second cell can be controlled, and as a result, the temperature of the first cell can be controlled. The air flow rate control unit can be configured using, for example, a valve that is linked to temperature fluctuations.

  Moreover, it is preferable to further include a cooling water supply unit that supplies cooling water to the air electrode of the second cell when the temperature of the first cell exceeds a second threshold temperature higher than the first threshold temperature. If only the flow control of the liquid fuel or the air cannot control the temperature of the first cell, and if the temperature of the first cell exceeds the second threshold temperature higher than the first threshold temperature, the second cell By supplying cooling water to the air electrode, it is possible to cool the first cell and prevent the first cell from deteriorating.

  Here, a specific configuration of the liquid fuel cell of the present embodiment will be illustrated with reference to FIG. FIG. 2 is an exemplification, and the scope of the present embodiment is not limited to the configuration of FIG. The liquid fuel cell of this embodiment includes a first cell 1 and a second cell 11, which are electrically separated from each other by an insulating film 50. The configurations of the first cell 1 and the second cell 11 are the same as those described in the first embodiment. Therefore, the second cell 11 has an electrolyte membrane having a higher liquid permeability than the first cell 1. However, in the first embodiment, a carbon material having excellent electrical conductivity and strength is usually used as the material of the flow path plate. However, in the second embodiment, the material of the flow path plate is electrically conductive. It is not limited to what has nature.

  The insulating film 50 has high thermal conductivity, and the first cell 1 and the second cell 11 are in thermal contact (that is, the heat generated in the second cell 11 is easily generated in the first cell 1). To be conducted). Specifically, the insulating film 50 is, for example, mixed with a matrix resin (for example, silicone rubber) and a heat conductive filler (for example, boron nitride), mixed and diluted in a solvent, and then formed into a sheet shape according to a doctor blade method. It can be prepared by a method of drying, pressing and vulcanizing.

  Liquid fuel is supplied to the fuel electrodes 3 and 13 of the first and second cells 1 and 11 from the liquid fuel container 40b in which the liquid fuel is accommodated via the liquid feed pump 20b. The fuel discharge ports of the fuel electrodes 3 and 13 are connected to the liquid fuel container 40b. Between the pump 20b and the fuel inlet of the fuel electrode 13, a valve (liquid fuel flow control unit) 30a that decreases the flow rate in conjunction with the temperature rise is interposed.

  The valve 30a includes a spring 31, a shape memory alloy spring 32, and a slider valve 33 as shown in FIG. The spring 31 is excellent in corrosion resistance and is made of a material whose force generated by temperature is substantially constant, and is made of, for example, stainless steel. As the shape memory alloy spring 32, for example, a Ti—Ni alloy having good shape memory characteristics and excellent corrosion resistance is used. Shape memory alloys are characterized in that they are soft in the martensite phase at low temperatures and generate little force, and hard and generate in the austenite phase at high temperatures. Utilizing these characteristics, since the generated force of the stainless spring 31 exceeds the generated force of the shape memory alloy spring 32 at low temperature, the slider valve 33 having a hollow shape moves downward (shown by a dotted line in the figure). A road is secured. Since the generated force of the shape memory alloy spring 32 exceeds the generated force of the stainless spring 31 at a high temperature, the slider valve 33 moves upward to shield the flow path.

  Since the fuel cell after being left for a long time is at a temperature of about room temperature, the valve 30a is in the “open” state (the state shown in FIG. 3). When the power supply of the fuel cell is turned on, liquid fuel is supplied to the fuel electrode 13 of the second cell 11, passes through the electrolyte membrane 12 with high permeability, and a chemical reaction with oxygen and heat generation occurs on the catalyst of the air electrode 14, and the fuel The entire battery is quickly heated. As the temperature of the fuel cell rises gradually, the generated force of the shape memory alloy spring 31 of the valve 30a rises and the valve is closed, so that the fuel flow rate supplied to the fuel electrode 13 of the second cell 11 is increased. Will decay. At the first threshold temperature T2 set lower than the limit temperature so that the temperature average matches the optimum reference temperature T1 for driving the first cell, the valve 30a is in the “closed” state, and the second cell 11 No further exothermic reaction occurs at, preventing overheating. In order to more accurately reflect the first cell 1 in the fuel flow rate, the valve 30a is preferably disposed adjacent to the first cell 1. Further, since air is continuously supplied to the air electrode 14 side of the second cell 11 even after the threshold temperature T2 is exceeded, the insulating film 50 having good heat conduction and the air electrode 14 side flow of the second cell 11 The road plate serves as a heat radiating plate, can cool the overheated first cell 1, and can suppress reaching a limit temperature that causes the first cell 1 to deteriorate.

  Since the second cell 11 is incorporated electrically separated from the first cell 1, the flow plate of the second cell 11 does not need to use a material having good electrical conductivity. In order to dissipate heat, it is more preferable to use a material having a small heat conduction resistance. For example, a metal plate mainly made of anodized aluminum or a stainless clad steel plate in which Ni, Ti, Cu, Fe, or the like is combined with stainless steel can be used. Accordingly, it is possible to provide a fuel cell capable of temperature control with a simple configuration without using a temperature control element such as a thermistor outside.

  As an air supply means, a blower pump 20 a (or a blower fan) is connected to the air supply ports of the air electrode 4 and the air electrode 14. Each air electrode discharge port is connected to the air electrode recovery container 40a, so that water discharged from the air electrode and excess liquid fuel are recovered. The water and excess liquid fuel recovered in the air electrode recovery container 40a may be returned to the liquid fuel container 40b by the liquid feed pump 20c. Thus, when using the water discharged | emitted from the air electrode, the liquid fuel (for example, 100% methanol) which does not contain water can be used as a fundamental fuel. Further, by interposing a concentration sensor (not shown), the fuel concentration in the liquid fuel recovery container 40b can be diluted. In addition, by cooling the circulating liquid fuel with the recovered water, it becomes possible to cool the fuel cell stack whose temperature has risen too much. Although not shown in FIG. 2, a valve (air flow control unit) is interposed between the blower pump 20a and the second air electrode inlet to supply air fuel to the second air electrode side. As with the fuel electrode side liquid fuel fuel, it is possible to change the temperature in conjunction with the cell temperature and shut off at the threshold temperature T2.

  Further, as indicated by a dotted line in FIG. 2, the air electrode 14 and the air electrode recovery container 40a of the second cell 11 are connected via a valve 30b that increases the flow rate in conjunction with the temperature rise. As the valve 30b, for example, a valve in which the arrangement positions of the shape memory alloy spring and the stainless spring are exchanged in the structure shown in FIG. 3 may be used. Alternatively, a valve having a structure having four shape memory alloys 34 and a bias spring 35 as shown in FIG. 4 may be used (reference document, AEM Society of Japan, Vol. 4, No. 4 (1996). , Pp. 31-36). The shape memory alloy plate 34 has an arc shape as indicated by a broken line in FIG. 4 at room temperature, and the flow path is closed by the restoring force of the bias spring. On the other hand, the shape memory alloy plate 34 heated to a certain level or more has a flat shape as shown by a solid line in FIG. The valve 30b becomes “open” when the second threshold temperature T3 set higher than the first threshold temperature T2 is exceeded, and the recovered water flows. Thereby, it is possible to cool the overheated fuel battery cell and to prevent reaching a limit temperature that causes deterioration of the fuel cell system.

  The present invention is not limited to the above-described embodiments, and various modifications can be made.

  FIG. 5 is a schematic diagram showing the configuration of the liquid fuel cell according to Example 1 of the present invention. This example corresponds to the first embodiment. This liquid fuel cell includes two types of cells, and has a configuration in which one second cell 202 is sandwiched between two first cells 201 arranged on both sides (first cell 201, first cell 201). The basic configuration of the two cells 202 is the same as that of the first cell 1 and the second cell 11 shown in FIG. The five cells are electrically connected to each other and are connected in series.

Here, a method for manufacturing the first cell 201 will be described. First, Nafion (registered trademark) made by DuPont having a film thickness of 170 μm was used as an electrolyte membrane, and a 22.3 mm × 22.3 mm anode electrode in which a Pt—Ru-based catalyst layer was applied on carbon cloth, and Pt on carbon cloth. The 22.3 mm × 22.3 mm cathode electrode coated with the catalyst layer was joined by hot pressing at 120 ° C. for 4 minutes at a pressure of 20 kgf / cm ² so that the catalyst layer was in contact with the electrolyte membrane. The membrane electrode assembly is assembled into an anode channel plate having an anode channel having a depth of 1 mm and a width of 1 mm and a cathode channel plate having a cathode channel having a depth of 1 mm and a width of 1 mm. One cell 201 was created.

  Next, a second cell 202 was formed in the same manner as the first cell 201 except that Nafion (registered trademark) made by DuPont having a film thickness of 50 μm was used.

An arrow 401 in FIG. 5 indicates a flow path of the methanol aqueous solution, which is supplied to each cell and discharged from each cell. A 2M aqueous methanol solution was sent to the anode channel at a flow rate of 1.0 ml / min, and air was sent to the cathode channel at a flow rate of 300 ml / min to generate power under a 0.1 A / cm ² load condition. The measurement conditions were room temperature of 24 ° C. and humidity of 40%, and the voltage of the whole cell connected in series was measured. The initial voltage per unit cell was 0.35V.

(Comparative Example 1) In the configuration of Example 1, power generation was performed under the same conditions as Example 1 except that the second cell 202 in FIG. 5 was replaced with the first cell 201 and only the first cell was stacked. The voltage dropped while the load of 0.1 A / cm ² could not be taken.

  From a comparison between Example 1 and Comparative Example 1, it was easily found that the liquid fuel cell of the present invention was excellent in restarting characteristics.

FIG. 6 is a schematic diagram showing a configuration of a liquid fuel cell according to Example 2 of the present invention. This example corresponds to the second embodiment. The first cell 201 was created by the same method as in Example 1. The second cell 203 was prepared by sandwiching a film prepared by the same method as that of the second cell 202 with a flow channel plate that was anodized after forming a flow channel having a depth of 1 mm and a width of 1 mm on an aluminum plate. Between the 1st cell and the 2nd cell, it laminated | stacked like FIG. 6 by interposing the commercially available insulating sheet 501 with favorable heat conductivity. The aqueous methanol solution was supplied to the second cell 203 by taking the structure shown in FIG. 3 and installing a valve 30a that reduces the flow rate in conjunction with the cell temperature so as to be in contact with the first cell 201. The flow rate on the outlet side for each temperature when the aqueous methanol solution was flowed through the flow path through the valve 30a at 1 ml / min was as shown in FIG. A 2M aqueous methanol solution was sent to the anode channel at a flow rate of 1.0 ml / min, air was sent to the cathode channel at a flow rate of 300 ml / min, and power was generated under a 0.1 A / cm 2 load condition. The measurement conditions were a room temperature of 24 ° C. and a humidity of 40%, and the voltage across the first cells 201 connected in series was measured. The initial voltage per unit cell was 0.4V.
There was no change in voltage after 10 hours of operation. The cell temperature during the measurement period was between 65 ° C and 75 ° C. From this, it was confirmed that the liquid fuel system of the present invention can prevent overheating and maintain a stable output even during long-time operation.

It is a perspective view which shows an example of the structure of the 1st Embodiment of this invention. It is a block diagram which shows an example of a structure of the 2nd Embodiment of this invention. It is a schematic sectional drawing which shows an example of the temperature interlocking flow control valve used for this invention. It is a schematic sectional drawing which shows an example of the temperature interlocking flow control valve used for this invention. It is a perspective view which shows the structure of the liquid fuel cell of Example 1 of this invention. . It is a perspective view which shows the structure of the liquid fuel cell of Example 2 of this invention. . It is a graph which shows the flow temperature characteristic of the temperature interlocking flow control valve concerning Example 2 of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,11: Liquid fuel cell 2,12: Electrolyte membrane 3,13: Fuel electrode 4,14: Air electrode 5,6,7: Flow path plate 8: Support substrate 20a, 20b, 20c: Pump 30a, 30b: Flow control valve 40a, 40b Aqueous solution container

Claims (14)

First cell, the second cell and the liquid fuel cell Ru provided with a liquid fuel flow control unit,
Each of the first cell and the second cell has an electrolyte membrane, and a fuel electrode and an air electrode arranged with the electrolyte membrane interposed therebetween,
A liquid fuel flow path capable of supplying liquid fuel to the fuel electrode;
The first cell and the second cell are disposed in thermal contact,
The electrolyte membrane of the second cell is formed so that the amount of liquid fuel that permeates from the fuel electrode side to the air electrode side is larger than the electrolyte membrane of the first cell,
The first cell is heated by the heat generated when the liquid fuel that has passed through the electrolyte membrane of the second cell reacts with oxygen at the air electrode of the second cell,
The liquid fuel flow rate control unit is provided so as to control the heat generation amount of the second cell by changing the flow rate per unit time of the liquid fuel supplied to the fuel electrode of the second cell. Liquid fuel cell. The liquid fuel flow rate control unit, so that the flow rate per unit at a first threshold temperature time becomes zero, per unit of liquid fuel supply time to the fuel electrode of the second cell in conjunction with the temperature of the first cell The liquid fuel cell according to claim 1 , wherein the flow rate is varied. The liquid fuel cell according to claim 2 , wherein the liquid fuel flow rate control unit includes a valve that interlocks with a temperature change. 4. The liquid fuel cell according to claim 3 , wherein the valve includes a member made of a shape memory alloy as a constituent element. First cell, the second cell and the liquid fuel cell Ru includes an air flow control unit,
Each of the first cell and the second cell has an electrolyte membrane, and a fuel electrode and an air electrode arranged with the electrolyte membrane interposed therebetween,
A liquid fuel channel capable of supplying liquid fuel to the fuel electrode and an air channel capable of supplying air to the air electrode;
The first cell and the second cell are disposed in thermal contact,
The electrolyte membrane of the second cell is formed so that the amount of liquid fuel that permeates from the fuel electrode side to the air electrode side is larger than the electrolyte membrane of the first cell,
The first cell is heated by the heat generated when the liquid fuel that has passed through the electrolyte membrane of the second cell reacts with oxygen at the air electrode of the second cell,
The air flow control unit is provided so as to control the heat generation amount of the second cell by changing the flow rate per unit time of the air supplied to the air electrode of the second cell. Fuel cell. The air flow rate controller controls the flow rate of air supplied to the air electrode of the second cell per unit time in conjunction with the temperature of the first cell so that the flow rate per unit time becomes zero at the first threshold temperature. The liquid fuel cell according to claim 5 , wherein The liquid fuel cell according to claim 6 , wherein the air fuel flow rate control unit includes a valve that interlocks with a temperature change. The liquid fuel cell according to claim 7 , wherein the valve includes a member made of a shape memory alloy as a constituent element. Temperature of the first cell, when exceeding the high second threshold temperature than the first threshold temperature, claim further comprising a cooling water supply unit for supplying cooling water to the air electrode of the second cell 2～4,6 The liquid fuel cell as described in any one of -8 . The electrolyte membrane of the second cell is made of the same material as the electrolyte membrane of the first cell, and film thickness than the electrolyte film of the first cell is rather thin,
The liquid fuel cell according to any one of claims 1 to 9, wherein the electrolyte membrane of the second cell is permeable to liquid fuel at 24 ° C. The liquid fuel cell according to any one of claims 1 to 10, wherein the electrolyte membrane of the first cell and the electrolyte membrane of the second cell are made of different materials. Air electrode of the second cell, liquid fuel cell according to any one of claims 1 to 11 comprising the CO poisoning tolerant catalyst. The second cell, liquid fuel cell according to any one of claims 1 to 12, characterized in that it is electrically separated from the first cell. An insulating film between the first cell and the second cell;
The liquid fuel cell according to claim 1, wherein the insulating film electrically separates the first cell and the second cell.

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