JP2005116360A - Fuel cell system and portable electronic component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system delivering a stable output and high power generating efficiency, in a fuel cell system using an unsealed fuel cell of DMFC type, and to provide a portable electronic component. <P>SOLUTION: The system is configured to include an unsealed fuel cell body 101 and a vibration motor 108. The vibration motor applies vibration to the fuel cell body, and air bubbles are blown off at an anode of the fuel cell body and stay there. Consequently, a contact area between the anode and liquid fuel recovers to an original state and the fuel cell body is capable of achieving a stable output and high power generating efficiency. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a fuel cell system that generates electric power by supplying liquid fuel directly to a fuel cell body, and a portable electronic device equipped with the fuel cell system.

Fuel cells are attracting attention as a next-generation clean and highly efficient energy source. In particular, polymer electrolyte fuel cells (PEFCs) with anode and cathode electrodes joined to both sides of a polymer electrolyte membrane have features that make them suitable as power sources for electric vehicles and distributed power sources for home use. And has been developing rapidly. In recent years, the direct methanol fuel cell (DMFC) that generates electricity by supplying methanol and dimethyl ether directly to the anode without reforming them is based on this polymer electrolyte fuel cell (PEFC) technology. Development is active. This direct methanol fuel cell (DMFC) is easy to miniaturize because it does not require a reformer or hydrogen container for reforming organic fuel such as methanol into a hydrogen-rich gas, and is attracting attention as a mobile power source. Has been.
The DMFC generally has a stack configuration in which fuel cells are connected in series, and a circulation type fuel cell system that forcibly supplies fuel and air to the fuel cells and a natural supply of fuel and air without taking the stack configuration Two types of open type fuel cell systems are known. Of these, the open type does not require an auxiliary machine such as a pump or a compressor for forcibly supplying fuel or air to the fuel cell body, and thus is easy to configure and effective for miniaturization (for example, patents). Reference 1).

A schematic view of the DMFC fuel cell is shown in FIG. In the fuel cell 10, an anode portion 2 and a cathode portion 3 are arranged on both sides of the solid polymer electrolyte membrane 1. The anode part 2 has a catalyst layer 4 and a fuel diffusion layer 6, and the cathode part 3 has a catalyst layer 5 and a gas diffusion layer 7. A Pt—Ru catalyst is used for the catalyst layer 4, and a Pt catalyst is used for the catalyst layer 5. The fuel diffusion layer 6 and the gas diffusion layer 7 serve as passages for supplying fuel and air to the catalyst layers 4 and 5, respectively, and must have a current collecting function, and are generally made of a porous conductive material. A certain carbon paper is used (for example, refer patent document 2).
On the other hand, in a DMFC that supplies liquid fuel directly to a fuel cell, for example, methanol and water react at the anode electrode by the following reaction mechanism.
CH ₃ OH + H ₂ O → CO ₂ + 6H ⁺ + 6e ⁻
For example, when the fuel is dimethyl ether, dimethyl ether and water react by the following reaction mechanism.
CH ₃ OCH ₃ + 3H ₂ O → 2CO ₂ + 12H ⁺ + 12e ⁻
As shown in the reaction mechanism described above, in a fuel cell that supplies direct fuel such as DMFC, CO ₂ is generated in the reaction of the anode electrode of the fuel cell. The generated CO ₂ passes through the fuel diffusion layer 6 and is released to the outside.
US Pat. No. 6,458,479 JP2002-56856

Since CO ₂ generated in the anode section 2 is a gas, it has a very large volume compared to the supplied fuel, and needs to be quickly recovered. However, since the fuel diffusion layer 6 is a porous material, gas tends to stay therein, and CO ₂ tends to stay in the fuel diffusion layer 6 and the catalyst layer 4 in the form of bubbles. Since CO ₂ is not released to the outside, the supply of fuel is not smoothly performed in the CO ₂ retention portion, and the effective area with which the fuel comes into contact is substantially reduced, resulting in a decrease in fuel cell performance. There is. Further, if the bubbles due to CO ₂ become a certain size, they are released from the fuel diffusion layer 6 and the catalyst layer 4, but since this action is performed irregularly, it is difficult to obtain stable fuel cell performance. There is also a problem.

In order to avoid these problems, for example, in Patent Document 2, a fuel supply path is arranged between the catalyst layer and the solid polymer film. However, this configuration assumes the above-described circulation type fuel cell and cannot be used for an open type fuel cell. Furthermore, in the said structure, since the catalyst layer and the solid polymer film are not contacting, the problem that the hydrogen ion conductivity between both falls will arise. In order to supplement the hydrogen ion conductivity, the fuel solution needs to be acidified, which causes a safety problem.
The present invention has been made to solve such problems, and in a fuel cell system using an open type fuel cell that generates power by supplying liquid fuel directly to the fuel cell body, a stable output and It is an object of the present invention to provide a fuel cell system having high power generation efficiency and a portable electronic device equipped with the fuel cell system.

The fuel cell system according to the first aspect of the present invention includes an open type fuel cell main body that generates power by naturally supplying liquid fuel to the anode part and air to the cathode part,
A vibration imparting device that gives the open fuel cell main body a vibration for gas exclusion that eliminates bubbles remaining in the anode part;
A control device for controlling the operation of the vibration applying device;
It is provided with.

  Further, the gas exclusion vibration can be configured to have a frequency of 10 Hz or more.

  Further, the vibration applying device may be configured to be a vibration motor.

  Further, the control device may be configured to perform operation control for periodically vibrating the open type fuel cell main body with respect to the vibration applying device.

  Furthermore, a portable electronic device according to a second aspect of the present invention includes the fuel cell system according to the first aspect, and is supplied with electric power from the fuel cell system.

  In the second aspect, the vibration applying device provided in the fuel cell system may be configured to vibrate the portable electronic device.

  In the second aspect, the control device provided in the fuel cell system is a gas exclusion vibration applied to the open fuel cell main body and a vibration applied to the portable electronic device to the vibration applying device. It can also be configured to perform operation control for generating device vibrations having a vibration pattern different from the exclusion vibrations.

  In the second aspect, the portable electronic device may be configured to be a mobile communication device.

According to the fuel cell system of the first aspect of the present invention and the portable electronic device of the second aspect of the present invention, the open type fuel cell is provided with a vibration applying device so as to give vibration to the open type fuel cell. Therefore, it is possible to effectively release the bubbles staying in the catalyst layer and the fuel diffusion layer of the open type fuel cell from the fuel cell to the outside. Thereby, the contact area of the catalyst layer or the fuel diffusion layer and the liquid fuel can be increased as compared with the time of bubble adhesion, and the original power generation amount can be recovered. Therefore, it is possible to provide a fuel cell system and a portable electronic device having a stable output and high power generation efficiency, and the portable electronic device can be miniaturized by including the fuel cell system.
In addition, it is possible to effectively promote the discharge of bubbles by setting the frequency to 10 Hz or more, and the manufacturing cost can be reduced by using the vibration motor.
Further, by periodically applying the vibration, the power consumption of the vibration applying device can be reduced.
Further, the portable electronic device can be downsized by vibrating the portable electronic device with the vibration applying device. Furthermore, by making the vibration applied to the open type fuel cell different from the vibration applied to the portable electronic device, erroneous recognition between the two can be prevented.

A fuel cell system according to an embodiment of the present invention and a portable electronic device including the fuel cell system will be described below with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected about the same component.
<First Embodiment>
FIG. 1 shows an outline of the fuel cell system of the present embodiment. The fuel cell system 100 includes, as a basic configuration, a fuel cell main body 101, a vibration applying device 108, and a control device 109. In this embodiment, a fuel tank 105, a fuel supply path 106, and a fuel holding unit 107 are further provided. Prepare.
The fuel cell main body 101 has the same configuration as that described in FIG. 4, and an anode portion 2 and a cathode portion 3 are arranged on both sides of the solid polymer electrolyte membrane 1. The anode part 2 has a catalyst layer 4 and a fuel diffusion layer 6, and the cathode part 3 has a catalyst layer 5 and a gas diffusion layer 7. In FIG. 1, illustration of the catalyst layers 4 and 5, the fuel diffusion layer 6, and the gas diffusion layer 7 is omitted for simplification of illustration. Further, the fuel cell main body 101 may have a single cell configuration composed of one cell, or may have a configuration in which a plurality are arranged on a substantially flat surface.

In the present embodiment, the anode unit 2 is disposed so as to be exposed in the fuel holding unit 107, and the liquid fuel 190 is naturally supplied from the fuel holding unit 107 to the anode unit 2. The natural supply refers to a supply form in which liquid fuel and air are brought into contact with electrodes without using an auxiliary machine such as a pump. The fuel holding unit 107 is preferably formed of a liquid tank in which the anode unit 2 is exposed and in contact with the liquid fuel 190, or a porous body into which the liquid fuel 190 can permeate. For example, polyurethane, polyester, polycellulose, or the like can be used as the porous material. Further, the fuel holding unit 107 has gas discharge pores and the like. Therefore, the gas composed of bubbles or the like contained in the liquid fuel 190 in the fuel holding unit 107 can be discharged to the outside of the fuel holding unit 107 through the pores.
The cathode part 3 is open to the outside air, and air is naturally supplied. For example, air supply may be forcibly performed using an auxiliary machine such as a fan.
The anode unit 2 and the cathode unit 3 are connected to an output unit 112 that is a unit that outputs electric power generated in the fuel cell main body 101.

  The fuel tank 105 contains a fuel for a fuel cell, and, as a suitable example, an organic solution such as methanol, ethanol, dimethyl ether, etc., particularly an aqueous methanol solution, and is connected to a fuel holding unit 107 via a fuel supply path 106. . The fuel supply path 106 has a configuration in which liquid fuel is naturally supplied from the fuel tank 105 to the fuel holding unit 107. For example, the structure may be formed of a thin tube having a capillary action, for example, or a porous material that allows liquid fuel to permeate. Therefore, the liquid fuel is supplied from the fuel tank 105 to the fuel holding unit 107. An auxiliary machine such as a pump can be provided for forcible supply.

  In this embodiment, the vibration applying device 108 is installed in contact with or close to the cathode portion 3 of the fuel cell main body 101, and vibrates the fuel cell main body 101. The installation location of the vibration applying device 108 is not limited to the cathode unit 3, and may be provided in contact with a casing (not shown) that partially or entirely contacts the fuel cell body 101 and protects the fuel cell body 101. Furthermore, another configuration in which vibration is transmitted indirectly may be adopted. The vibration generating means as the vibration applying device 108 is not particularly limited, but it is preferable to use a vibration motor as in the present embodiment because of its small size and low cost. The vibration motor is a vibration generating motor used in, for example, a mobile phone. Further, the electric power for operating the vibration applying device 108 may be supplied from the fuel cell main body 101 or from another power source.

The control device 109 is a device that controls the operation of the vibration applying device 108, and for example, a microcomputer or the like can be used. As the operation control, in the present embodiment, the supply voltage is controlled so as to generate a frequency of 10 Hz or more for the vibration motor as the vibration applying device 108. By generating a frequency of 10 Hz or more, carbon dioxide bubbles generated and staying in the anode portion 2 during power generation can be effectively eliminated from the fuel cell main body 101. Further, the frequency may be 10 Hz or more, and therefore the vibration applying device 108 may generate ultrasonic vibration. When ultrasonic vibration is used, the vibration applying device 108 uses an ultrasonic wave generation source such as an ultrasonic oscillator including a piezoelectric conversion element instead of the vibration motor. Further, since the bubbles generated in the anode part 2 are attached to the surface of the anode part 2, the direction in which the vibration is applied is preferably an orthogonal direction 191 orthogonal to the anode part 2. By applying vibration in the orthogonal direction 191, bubbles attached to the surface can be more effectively shaken off from the surface.
Further, as the operation control, in the present embodiment, vibration is periodically generated. As an example, after maintaining the state of no vibration for 60 seconds, the operation of applying vibration to the fuel cell body 101 for 5 seconds is repeated. In addition, instead of the periodic vibration application control as described above, control may be performed so that vibration is continuously applied, or control may be performed so that vibration is applied irregularly. Further, when the control device 109 is configured to monitor the power generation amount of the fuel cell main body 101 via the output unit 112, when the power generation amount falls below a specified value, the power generation amount is set to the specified value for a certain period. It is also possible to control so that the vibration by the vibration applying device 108 is applied to the fuel cell main body 101 until the value exceeds.
The electric power of the control device 109 may be supplied from the fuel cell main body 101 or from another power source.

The operation of the fuel cell system 100 configured as described above will be described below.
Liquid fuel is supplied from the fuel tank 105 through the fuel supply path 106 to the fuel holding unit 107, and the liquid fuel 190 is naturally supplied from the fuel holding unit 107 to the anode unit 2. On the other hand, air is naturally supplied to the cathode portion 3. In the anode part 2 and the cathode part 3, electric power is generated by the reaction of the catalytic action of the catalyst layer that each has, and electric power is supplied to the output part 112. At this time, in the anode part 2, gas is generated by the above reaction, for example, CO ₂ is generated if the liquid fuel is an aqueous methanol solution. Part of the generated CO ₂ passes through the pores provided in the fuel holding unit 107 and is released to the outside, but part of the CO ₂ stays in the catalyst layer and the fuel diffusion layer in the anode unit 2.
Here, the vibration applying device 108 applies vibration to the fuel cell main body 101 by the above-described control operation by the control device 109. By applying vibration to the fuel cell main body 101, the gas staying in the catalyst layer and the fuel diffusion layer in the anode portion 2 is shaken off and removed.

As described above, according to the fuel cell system 100 of the present embodiment, the carbon dioxide staying in the catalyst layer 4 and the fuel diffusion layer 6 of the anode portion 2 by applying vibration to the fuel cell main body 101 by the vibration applying device 108. A gas such as a gas can be removed from the catalyst layer 4 and the fuel diffusion layer 6 by the vibration and effectively removed. As a result, the contact area of the liquid fuel 190 in the catalyst layer 4 and the fuel diffusion layer 6 is increased as compared to when bubbles are attached, and thus the amount of power generation is recovered. Therefore, stable electric power can be output from the output unit 112 by applying the vibration. Further, for example, when the fuel cell body 101 is a semi-open type fuel cell that naturally supplies fuel to the anode part 2 and forcibly supplies air to the cathode part 3, the vibration applying device 108 and the control device are also provided. 109 can be provided.
The configuration of the fuel cell system 100 of the present embodiment is an example. For example, as shown in FIG. 2, a fuel cell in which the fuel tank 105 is also used as the fuel holding unit 107 and the fuel supply path 106 is omitted. The configuration of the system 115 can also be adopted. That is, it is only necessary to provide the vibration applying device 108 that vibrates the fuel cell main body 101, and the configuration of the other parts can be changed as appropriate.

Second Embodiment
Taking the fuel cell system 100 described above as an example, a portable electronic device of the present embodiment that includes the fuel cell system 100 and that is supplied with electric power from the fuel cell system 100 will be described below with reference to FIG. . In FIG. 3, description of components that are not related to the fuel cell system 100 such as a microcomputer and a display unit provided in the portable electronic device 120 is omitted. The portable electronic device 120 corresponds to, for example, a notebook personal computer or a cellular phone. In the present embodiment, a cellular phone is taken as an example.
The fuel cell system 100 is built in or directly connected to the portable electronic device 120 and is integrated with the portable electronic device 120. The control device 109 may be arranged in the portable electronic device 120 and may also be used as another control device, for example, a microcomputer for the portable electronic device 120.
In the second embodiment, the vibration applying device 108 is disposed in the fuel cell system 100. However, the vibration applying device 108 may be disposed in the portable electronic device 120 in the vicinity of the fuel cell main body 101. In this case, it goes without saying that the vibration applying device 108 can apply vibration to the portable electronic device 120.

The operation of the portable electronic device 120 configured as described above will be described below.
The fuel cell system 100 generates power as described above, and the vibration applying device 108 applies vibration to the fuel cell main body 101 as described above under the control of the control device 109. Therefore, the gas staying in the anode part 2 of the fuel cell main body 101 is excluded.
On the other hand, the portable electronic device 120 receives power from the output unit 112 of the fuel cell system 100 and operates. Since the gas staying in the anode unit 2 is excluded as described above, the portable electronic device 120 is always supplied with stable power from the fuel cell system 100.
Further, when the portable electronic device 120 itself needs to vibrate like a mobile phone, the vibration applying device 108 can be used as a vibration source for the portable electronic device 120. In this case, the control device 109 may be configured to control vibration generation for the portable electronic device 120. Thus, by sharing the vibration source between the portable electronic device 120 and the fuel cell body 101, it is not necessary to provide a separate vibration source within the portable electronic device 120, and the overall configuration of the device can be made compact. Can do.
When the vibration source is shared, the control device 109 makes the vibration pattern in the device vibration that vibrates the portable electronic device 120 itself different from the vibration pattern in the gas exclusion vibration that vibrates the fuel cell main body 101. It is preferable to control it. By making the vibration patterns of the two different, the user of the portable electronic device 120 is prevented from misidentifying the vibration for gas exclusion for the fuel cell main body 101 as the vibration for the device of the portable electronic device 120 itself. be able to.

An embodiment of the fuel cell system 115 shown in FIG. 2 will be described below.
The liquid fuel 190 is a 2M aqueous methanol solution. As the fuel cell main body 101, a single cell having the configuration shown in FIG. 4 was used, and for the solid polymer membrane 1, trade name Nafion (manufactured by DuPont), which is a perfluorocarbon sulfonic acid polymer material, was used. Carbon paper is used for the gas diffusion layer 7 and the fuel diffusion layer 6, and a Pt-Ru carrier carbon catalyst is used in an amount of 1.7 mg / cm ² for the catalyst layer 4 of the anode portion 2, and the catalyst for the cathode portion 3 is used. For layer 5, a Pt-treated carbon catalyst was used in an amount of 1.5 mg / cm ² . The cell area of the fuel cell main body 101 is 16 cm ² .
The fuel supply to the anode part 2 and the air supply to the cathode part 3 are natural supply.

  Table 1 shows operating conditions of the vibration applying device 108 in the configuration of the above-described embodiment. As shown in Table 1, no vibration was given at all in the comparative example.

  The evaluations of Examples 1 and 2 and Comparative Example shown in Table 1 were made by comparing the amount of power generated when the fuel cell body 101 was operated at an output of 0.4 V for 1 hour. The evaluation results are shown in Table 2.

  As is clear from Table 2, the power generation amount of the fuel cell is greatly increased in Example 1 and Example 2 to which vibration is applied compared to the comparative example in which vibration is not applied. Therefore, it can be seen that applying vibration to the fuel cell main body 101 by the vibration applying device 108 is effective.

  Table 3 shows the amount of power generated when a constant frequency is applied to the fuel cell main body 101 at a rate of 5 seconds in 60 seconds and operated at 0.4 V for 1 hour.

  As is clear from Table 3, when it is found that the amount of power generation is larger and the application of vibration is more effective when the vibration is applied as in the above case, the power generation amount is substantially constant regardless of the change in the frequency. From this, it can be seen that the applied frequency may be about 10 Hz or more.

  The present invention is particularly useful for a fuel cell system that generates electric power by supplying liquid fuel directly to the fuel cell main body, and an electronic device equipped with the fuel cell system.

FIG. 1 is a diagram illustrating a configuration example of a fuel cell system according to an embodiment of the present invention. FIG. 2 is a diagram showing another configuration example of the fuel cell system shown in FIG. FIG. 3 is a diagram illustrating an example of a portable electronic device that is an embodiment of the present invention. FIG. 4 is a diagram showing the configuration of the fuel cell main body.

Explanation of symbols

2 ... anode part, 3 ... cathode part,
101 ... Fuel cell main body, 108 ... Vibration applying device, 109 ... Control device,
190: liquid fuel, 191: orthogonal direction.

Claims (8)

An open type fuel cell body (101) for generating electricity by naturally supplying liquid fuel (190) to the anode part (2) and air to the cathode part (3);
A vibration imparting device (108) for applying a gas-exclusion vibration to the open-type fuel cell main body to eliminate bubbles remaining in the anode part;
A control device (109) for controlling the operation of the vibration applying device;
A fuel cell system comprising:   The fuel cell system according to claim 1, wherein the gas exclusion vibration has a frequency of 10 Hz or more.   The fuel cell system according to claim 1, wherein the vibration applying device is a vibration motor.   4. The fuel cell system according to claim 1, wherein the control device performs operation control to periodically vibrate the open type fuel cell main body with respect to the vibration applying device. 5.   A portable electronic device comprising the fuel cell system according to claim 1 and receiving power supply from the fuel cell system.   6. The portable electronic device according to claim 5, wherein the vibration applying device provided in the fuel cell system vibrates the portable electronic device.   The control device provided in the fuel cell system differs from the vibration applying device in that the vibration for gas exclusion given to the open type fuel cell main body and the vibration given to the portable electronic device for the vibration applying device. The portable electronic device according to claim 6, wherein operation control is performed to generate device vibration having a vibration pattern. The portable electronic device according to any one of claims 5 to 7, wherein the portable electronic device is a mobile communication device.

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