JP3376653B2 - Energy conversion device and electrode - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an energy conversion device and an electrode, and more particularly to an energy conversion device and an electrode for directly converting chemical energy and electric energy of a substance.

[0002]

2. Description of the Related Art The energy conversion device mentioned here is a device for converting chemical energy and electric energy of a substance,
For example, a fuel cell that reacts hydrogen as a fuel with oxygen and converts its chemical energy into electrical energy, or conversely, hydrogen that receives electrical energy and electrolyzes water to generate hydrogen and oxygen (oxygen ) Represented by a generator.

At the electrodes of these energy conversion devices, a reaction for producing water or a reverse reaction for decomposing water is usually carried out. For example, in a fuel cell electrode, the following formula (1)
The reaction for generating water shown in (1) is generally performed, and in the water electrolysis system, the reaction for decomposing water shown by the following formula (2) is generally performed.

[0004]   Formula (1)       Cathode reaction: 2H ++ 2e − + (1/2) O2 → H2O       Anode reaction: H2 → 2H ++ 2e−   Formula (2)       Anode reaction: H2O → 2H ++ 2e − + (1/2) O2       Cathode reaction: 2H ++ 2e- → H2

In order to carry out these reactions continuously,
It is necessary to continuously supply the reactant to the electrode and remove the product from the vicinity of the electrode. For example, in the case of a polymer electrolyte fuel cell, it is necessary to continuously supply oxygen and remove water as a product at the cathode . If the product water is not removed, water will stay near the electrodes,
This is because the operating efficiency is reduced and the reaction is stopped in some cases. At the anode, it is necessary to continuously supply hydrogen gas and smoothly diffuse hydrogen ions into the electrolyte membrane. Since the hydrogen ions to move water bonded to the electrolyte membrane becomes hydrated state in the electrolyte membrane, such that water in the vicinity of the anode is not insufficient, from the outside to the anode with <br/> near the electrolyte membrane Need to replenish water. Ano
If the water near the battery is insufficient, the diffusion of hydrogen ions into the electrolyte membrane is hindered, and the hydrogen ions in the electrolyte membrane become insufficient,
This is because the reaction at the cathode is hindered.

Conventionally, generated water near the electrodes is removed or makeup water is supplied, and at the same time, fuel gas is supplied to the electrodes,
As a device for efficiently and continuously converting energy,
The electrode is provided with a convex portion made of a hydrophilic portion and a concave portion made of a water repellent portion, and the unevenness serves to remove generated water or supply makeup water and supply fuel gas to the electrode (for example, JP-A-4-12462). , Hydrophilic gas diffusion membrane with multiple penetrations is bonded to hydrophilic reaction membrane to form an electrode. Through the penetrations, generated water is removed or makeup water is supplied and the hydrophobic gas diffusion membrane is used for fuel gas. An apparatus (for example, Japanese Laid-Open Patent Publication No. 3-182052) for supplying the electricity has been proposed.

[0007]

However, in an apparatus for providing irregularities on an electrode, it is necessary to make the intervals of the irregularities small in order to improve the effect. If the intervals of the irregularities are made small, it becomes difficult to process the electrodes. At the same time, there was a problem that the manufacturing cost increased. In addition, no matter how fine the intervals are, in machining, microscopically, the removal of generated water, the supply of makeup water, and the supply of gas become uneven. Where the generated water is not removed, the makeup water is not supplied, or the gas is not sufficiently supplied, the electrode reaction is hindered, and the operation efficiency is reduced as a whole.

Further, in an apparatus for bonding a gas diffusion film to a hydrophilic reaction film, it is necessary to precisely process a plurality of members, bond them to form an electrode, and further bond an electrolyte. A hot pressing method is generally used for joining these materials by applying heat and pressure at the same time. However, since a plurality of members having different material properties are joined, there is a problem that the joining becomes extremely difficult. Further, even if joining is possible, there arises a problem that the yield is low.

These problems are not limited to the polymer electrolyte fuel cell, and can be applied to other fuel cells such as phosphoric acid fuel cells and various energy conversion devices such as so-called water electrolyzers. . Further, the above-mentioned problem that the generated water cannot be efficiently removed or the makeup water cannot be efficiently supplied and the gas cannot be efficiently supplied at the same time is not limited to the electrode used in the energy conversion device.

The energy conversion device of the present invention aims to solve these problems and efficiently and continuously convert energy, and the electrode of the present invention aims to simultaneously satisfy hydrophilicity and water repellency. , Adopted the following configuration.

[0011]

A first energy conversion device of the present invention is an energy conversion device which comprises a cathode , an anode and an electrolyte, and which directly converts chemical energy and electric energy of a substance into the cathode. Or Ano
At least one of the cords is formed by mixing hydrophilic carbon fibers having hydrophilicity and water-repellent carbon fibers having water repellency.

[0012] The second energy conversion device of the present invention, cathode
In an energy conversion device that includes a cathode , an anode, and an electrolyte disposed between the electrodes, and that directly converts chemical energy and electric energy of a substance, the cathode has hydrophilic carbon fibers having hydrophilicity and a hydrophobic carbon fiber. First, a water-repellent carbon fiber having water-based property is formed based on an electrochemical reaction in the cathode .
Formed are mixed at a ratio of, the anode is formed by a hydrophilic carbon fibers having a hydrophilic and a water-repellent carbon fiber having water repellency mix at a second rate that is based on the electrochemical reaction at the anode It is characterized by being done.

In such an energy conversion device,
Hydrophilic carbon fiber having a hydrophilic property
And the water-repellent carbon fiber having water repellency were set to a predetermined ratio.
Carbon cloth, carbon paper or carbon fiber
Can be formed as a belt .

On the other hand, it is used in this energy conversion device.
The electrode has hydrophilic carbon fiber having hydrophilicity and water repellency
Water-repellent carbon fibers mixed with each other.
Further, the hydrophilic carbon fiber and the water-repellent carbon fiber may be woven in a predetermined ratio to form a carbon cloth. Further, the electrode may be formed as carbon paper or carbon felt in which the hydrophilic carbon fiber and the water-repellent carbon fiber are mixed in a predetermined ratio.

[0015]

In the first energy conversion system of the present invention configured as described above, the hydrophilic carbon fibers remove generated water or supply makeup water, and the water repellent carbon fibers repel water to supply gas. Or eliminate it. Therefore, it is possible to efficiently and continuously perform the electrochemical reaction at the electrodes.

A second energy conversion device of the present invention is a first energy conversion device based on an electrochemical reaction of hydrophilic carbon fibers having hydrophilicity and water-repellent carbon fibers having water repellency at a cathode .
Mix at a rate of by forming the cathode, Ca
Smooth the electrochemical reaction in the sword . In addition, a hydrophilic carbon fiber having hydrophilicity and a water-repellent carbon fiber having water repellency are formed on the anode based on an electrochemical reaction.
Ano by forming the anode mix in a ratio of
Smoothes the electrochemical reaction in the battery.

In the electrode of the present invention, the hydrophilic carbon fiber exhibits hydrophilicity and the water repellent carbon fiber exhibits water repellency. As a result, the hydrophilic carbon fibers remove generated water or supply makeup water, and the water-repellent carbon fibers supply or remove gas.

Here, if the electrode is formed as a carbon cloth in which hydrophilic carbon fibers and water-repellent carbon fibers are woven at a predetermined ratio, a carbon cloth exhibiting both hydrophilicity and water repellency can be obtained. . Further, when the electrode is formed as carbon paper or carbon felt in which hydrophilic carbon fibers and water-repellent carbon fibers are mixed in a predetermined ratio, carbon paper or carbon exhibiting hydrophilicity and water repellency at the same time. It is possible to obtain a felt and directly form an electrode in an arbitrary shape.

[0019]

Preferred embodiments of the present invention will be described below in order to further clarify the structure and operation of the present invention described above. FIG. 1 is a schematic diagram of a cell structure of a polymer electrolyte fuel cell which is an embodiment of the present invention. As shown,
The cell comprises an electrolyte 10, a cathode 20 and an anode 3
0, gas flow path structures 40 and 50 forming flow paths for the cathode- side fuel and the anode- side fuel, and a separator 60 for partitioning each cell.

The cathode 20 and the anode 30 are made of carbon cloth woven with carbon fibers, and platinum or an alloy of platinum and another metal is supported on carbon powder as a catalyst, and the carbon powder is carbon cloth. Kneaded or applied in the gap. More specifically, the cathode 20 and the anode
The door 30 has the structure shown in FIG. FIG. 2 is a cathode
It is an enlarged view of a portion of the over de 20 or anode 30. As shown, cathode 20 and anode 3
No. 0 is formed by weaving the warp yarns 22 made of a bundle of hydrophilic carbon fibers having hydrophilicity and the weft yarns 24 made of a bundle of water-repellent carbon fibers having water repellency substantially evenly. Therefore, the proportions of the hydrophilic carbon fibers and the water-repellent carbon fibers that are mixed are substantially equal. Here, the hydrophilic carbon fiber is a normal carbon fiber. Normal carbon fiber exhibits hydrophilicity when it is not subjected to any processing.

The water repellent carbon fiber is obtained as follows.
First, an ordinary carbon fiber is dispersed in polytetrafluoroethylene (for example, Polyflon D manufactured by Daikin Industries, Ltd.).
-1). Next, after drying in air at room temperature for a while, it is dried in air at a temperature of 100 ° C. for 30 minutes to 1 hour to completely evaporate the water content of the dispersion. Then, in a nitrogen atmosphere, it is heated at 250 ° C. to 300 ° C. for 2 hours to 3 hours, and polytetrafluoroethylene is baked on the surface of the carbon fiber to obtain a water repellent carbon fiber. The water-repellent carbon fiber thus obtained exhibits water repellency due to the polytetrafluoroethylene formed on the surface of the carbon fiber.

The electrolyte 10 is an ion exchange membrane formed of a polymer material, for example, a fluorine resin, and exhibits good electric conductivity in a wet state. The gas flow channel structures 40 and 50 are made of porous carbon having gas permeability and have a porosity of 40 to 80%. Further, the gas flow path structure 40 has a flow path for the oxygen-containing gas, which is the cathode fuel, and the cathode 20.
A flow path 42 that forms a water collection path for the water generated in 1. is formed, and a flow path 52 for a mixed gas of hydrogen-containing gas that is anode fuel and water vapor is formed in the gas flow path structure 50. The separator 60 is formed of gas-impermeable carbon that is made gas-impermeable by compressing carbon, and is used for stacking cells formed by the electrolyte 10, the electrodes 20, 30, and the gas flow path structures 40 and 50. Make a partition.
In this embodiment, the gas flow channel structures 40 and 50 and the separator 60 are formed separately, but the gas flow channel structure 40 and the separator 60 are integrally formed of gas impermeable carbon or the gas flow channel. Structure in which the structure 50 and the separator 60 are integrally formed by gas impermeable carbon, the gas flow path structures 40 and 50, and the separator 60
A configuration in which is integrally formed of gas impermeable carbon is also suitable.

In the polymer electrolyte fuel cell thus constructed, hydrogen and oxygen react with each other in the cathode 20 and the anode 30 by the chemical reaction represented by the above-mentioned formula (1), and the reaction energy (chemical energy) is directly converted into electricity. Convert to energy.

On the surface of the catalyst (platinum or the like) kneaded or applied to the cathode 20, water is produced by the above reaction. When this water stays near the cathode 20, the above reaction is hindered. The hydrophilic carbon fiber warp yarns 22 guide this water to the flow passage 42 formed by the gas flow passage structure 40 and the cathode 20 and remove it from the vicinity of the catalyst. On the other hand, the weft thread 24 of the water-repellent carbon fiber repels water from the periphery of the fiber and guides the oxygen-containing gas to the catalyst surface from the contact surface between the gas flow channel structure 40 and the cathode 20 or the flow channel 42. Therefore,
In the cathode 20, the water generated by the warp yarns 22 is transferred and the generated water is removed, and the weft yarns 24 supply electrons and oxygen-containing gas. As a result, the above reaction is efficiently and continuously performed on the catalyst surface of the cathode 20.

On the catalyst surface of the anode 30, a reaction in which hydrogen gas (H2) becomes hydrogen ions (H +) is performed. When the hydrogen ions move from the catalyst surface through the electrolyte 10 to the cathode 20 in a hydrated state, water is insufficient near the catalyst surface. The warp yarn 22 made of the hydrophilic carbon fiber of the anode 30 is capable of removing this deficient water.
Water adhering to the surface of the anode 30 on the side of the flow channel 52 is guided to near the surface of the catalyst to make up for it. Since a large amount of water vapor is contained in the gas flowing through the flow channel 52, water is always attached to the surface of the anode 30 on the flow channel 52 side. In addition, the weft yarn 24 made of the water-repellent carbon fiber of the anode 30
Guides hydrogen gas to the catalyst surface from the contact surface between the gas flow channel structure 50 and the anode 30 or the flow channel 52. Therefore, in the anode 30, the warp yarns 22 receive electrons and make up for the insufficient water, and the weft yarns 24 receive electrons and supply hydrogen gas. As a result, the above reaction is efficiently and continuously performed on the catalyst surface of the anode 30.

In the polymer electrolyte fuel cell described above,
Since the cathode 20 and the anode 30 are formed by using the hydrophilic carbon fiber and the water-repellent carbon fiber, the produced water is removed to the flow channel 42 without being retained in the cathode 20, and the insufficient water is sufficiently produced in the anode 30. At the same time, the fuel gas can be supplied to the cathode 20 and the anode 30 smoothly. As a result, the electrochemical reaction at the electrode can be continuously and stably performed. Therefore, operating efficiency can be improved and stable electric power can be obtained.

The polymer electrolyte fuel cell can generally be miniaturized by increasing the load current density. However, when the load current density is suddenly changed, the water content of the electrolyte 10 is changed and the internal resistance is increased. It tends to fluctuate. In the present embodiment, the generated water is smoothly removed and the insufficient water is replenished even if the load current density is increased. Therefore, it is possible to prevent the fluctuation of the water content of the electrolyte 10 and reduce the size. Therefore, it is effective when it is installed in a limited space, for example, when it is installed in a vehicle or the like.

Furthermore, since the electrode is formed by weaving the thread made of the hydrophilic carbon fiber and the thread made of the water-repellent carbon fiber, the electrode can be manufactured more easily than the machined one. It can be manufactured at low cost.

In the embodiment, the warp yarns 22 made of hydrophilic carbon fibers and the weft yarns 24 made of water-repellent carbon fibers are evenly woven to form an electrode so that the ratio of the hydrophilic carbon fibers to the water-repellent carbon fibers is substantially equal. However, various ratios can be used according to the purpose of use. Also, this ratio is
It is desirable to set it according to the type of battery and operating condition. In the case of the polymer electrolyte fuel cells described in the examples, if the load current density is operated in a small region, the amount of water produced per unit time is small, so the proportion of the hydrophilic carbon fibers may be small. If you operate in a region where the load current density is large, the amount of water produced per unit time will increase, so
For efficient operation, it is desirable to increase the proportion of hydrophilic carbon fibers. Further, when the operating state changes, such as when the load current density changes with time, it is desirable to determine which load current density should be focused on for operation and to determine the proportion of the hydrophilic carbon fibers. The ratio of the hydrophilic carbon fibers to the water-repellent carbon fibers can be changed by changing the number of yarns (weaving density) per unit length of the warp yarn 22 or the weft yarn 24.

In the embodiment, the warp yarn 2 made of hydrophilic carbon fiber is used.
2 and the weft yarn 24 made of the water-repellent carbon fiber were woven to form an electrode. However, as in the electrode shown enlarged in FIG. 3, the warp yarn 22a made of the hydrophilic carbon fiber and the warp yarn 22b made of the water-repellent carbon fiber are alternately formed. It is also preferable that the arranged warp yarns and the weft yarns in which the weft yarns 24a made of hydrophilic carbon fibers and the weft yarns 24b made of water-repellent carbon fibers are alternately arranged are woven to form an electrode. In this case, the arrangement of the warp yarns, the weft yarns, or both of the hydrophilic carbon fibers and the water-repellent carbon fibers may be periodic or random. The ratio of the hydrophilic carbon fiber and the water repellent carbon fiber in this electrode is changed by changing the ratio of the yarns 22a and 24a made of the hydrophilic carbon fiber and the yarns 22b and 24b made of the water repellent carbon fiber in the warp or weft. It can be performed by arranging them.

Further, as in the electrode shown enlarged in FIG. 4, it is also preferable that the electrodes are formed by weaving warp yarns 22c and weft yarns 24c in which hydrophilic carbon fibers and water-repellent carbon fibers are mixed almost evenly. is there. In this case, the threads for weaving the electrodes are hydrophilic carbon fibers 23 (carbon fibers having a cross section without hatch) and water-repellent carbon fibers 25 (carbon fibers having a cross section with hatch) as shown in FIG. ) And are mixed so that they are almost even. The thread for weaving the electrode is usually composed of a bundle of hundreds to thousands of carbon fibers. The ratio of the hydrophilic carbon fiber and the water repellent carbon fiber of the electrode can be changed by changing the ratio of the hydrophilic carbon fiber 23 and the water repellent carbon fiber 25 which are mixed.

Further, like the thread illustrated in FIG. 6, a thread 26 made of a hydrophilic carbon fiber and a thread 27 made of a water-repellent carbon fiber are twisted into a twisted thread 28, and the twisted thread 28 is used as a warp thread and a weft thread. A configuration in which the electrodes are woven in is also suitable.
In this case, the twisted yarn 28 is preferably twisted with three or more yarns in addition to two twisted yarns. The ratio of the hydrophilic carbon fiber and the water repellent carbon fiber of the electrode is changed by changing the thickness of the thread 26 made of the hydrophilic carbon fiber and the thread 2 made of the water repellent carbon fiber.
It can be done by changing the thickness of 7,
This can also be done by increasing the number of twisted threads and changing the ratio.

In the embodiment, the warp yarns 22 and the weft yarns 24 are woven in two axes (vertical axis and horizontal axis), but a configuration in which they are woven in three or more axes is also suitable. In addition, the cathode 20 and the anode
Although the ratio of the hydrophilic carbon fibers and the water-repellent carbon fibers of the cord 30 is made equal in plan view, a non-uniform constitution may also be acceptable.

Further, in the embodiment, the cathode 20 and the anode
Although the electrode 30 is the same electrode, a configuration with different electrodes, for example, only one of the cathode 20 and the anode 30 is formed of hydrophilic carbon fiber and water repellent carbon fiber, and the other is configuration in accordance with the material and, Caso
A configuration in which the ratio of the hydrophilic carbon fibers of the cord 20 to the water-repellent carbon fibers and the ratio of the anode 30 are different is also suitable. Depending on the operating conditions, the water generated at the cathode 20
In some cases, the water shortage in the anode 30 may affect the operating efficiency, and in this case, it is desirable that the proportion of the hydrophilic carbon fibers in the cathode 20 be larger than that in the anode 30.

Next, a polymer electrolyte fuel cell according to a second embodiment of the present invention will be described. The cell structure of the polymer electrolyte fuel cell of the second embodiment is the same as the cell structure of the polymer electrolyte fuel cell of the first embodiment except the structures of the cathode 20 and the anode 30. The cathode 20a and the anode 30a of the second embodiment are, as shown in FIG.
A hydrophilic carbon fiber having a length of 1 mm to 10 mm and a water-repellent carbon fiber having a length of 1 mm to 10 mm are mixed in an irregular and arbitrary direction at a substantially equal ratio to form a carbon paper or a carbon felt having a thickness α. It is a thing. In this electrode, carbon or an alloy of platinum and another metal is supported as a catalyst on carbon powder, and the carbon powder is kneaded or applied in the gap of the carbon cloth. Since the water-repellent carbon fiber can be obtained by performing the same treatment as that of the first embodiment, the description thereof will be omitted.

Also in the cathode 20a and the anode 30a of the solid polymer electrolyte fuel cell of the second embodiment thus constituted, hydrogen and oxygen react with each other by the chemical reaction represented by the formula (1), and the reaction energy (chemical energy). Is directly converted into electric energy.

The hydrophilic carbon fiber mixed in the cathode 20a, the water produced in the catalyst (such as platinum) surface of the cathode 20a is guided to the flow path 42 removed from the vicinity of the catalyst. In addition, the cathode
Water repellent carbon fiber over de 20a is water from the surrounding fibers have Ji repellent directs oxygen-containing gas to the catalyst surface. On the other hand, Anoh
Hydrophilic carbon fibers de 30a is a flow path 5 of the anode 30 for the shortage of water due to the hydrogen ions move in a hydrated state
2 Guide water from the surface to make up for it. Further, the water-repellent carbon fiber of the anode 30a guides hydrogen gas to the catalyst surface. Due to these actions, the reactions at the cathode 20b and the anode 30b are efficiently and continuously performed.

In the polymer electrolyte fuel cell of the second embodiment described above, since the cathode 20a and the anode 30a are made of carbon paper or carbon felt formed of hydrophilic carbon fiber and water repellent carbon fiber, they are used as electrodes. The manufacturing can be further facilitated and the cost can be reduced as compared with the machined one. Particularly when the electrode is formed by cutting after forming carbon paper or carbon felt, the cut portion does not fray, so that the cut portion does not need to be treated, and the manufacturing process can be simplified. Further, since carbon paper or carbon felt can be directly formed into a free shape, if it is formed directly into the shape of the electrode, no secondary processing is required.

Since the cathode 20a and the anode 30a are formed of the hydrophilic carbon fiber and the water repellent carbon fiber, the water generated in the cathode 20a is removed to the flow channel 42 without staying, and the water lacking in the anode 30a is removed. The fuel gas can be sufficiently supplemented and the fuel gas can be smoothly supplied. As a result, it is possible to always keep the vicinity of the catalyst surface in a good state, reduce the internal resistance, improve the operation efficiency, and obtain stable power. Further, similarly to the first embodiment, even if the load current density is suddenly changed, the generated water is smoothly removed and the insufficient water is replenished, so that the water content of the electrolyte 10 is stable and the load current density is increased to increase the solid content. The polymer fuel cell can be miniaturized.

In the second embodiment, the ratio of the hydrophilic carbon fiber and the water repellent carbon fiber is set to be substantially equal, but this ratio is determined by the kind of the battery and the operating condition, as in the first embodiment. Therefore, various ratios can be used according to the purpose of use.

Next, a polymer electrolyte fuel cell according to a third embodiment of the present invention will be described. Cell structure of a polymer electrolyte fuel cell of the third embodiment, the cathode 20a and anode of the cell structure of a polymer electrolyte fuel cell of the second embodiment
They are identical except for the structure of the de 30a. Caso of the third embodiment
The cathode 20b and the anode 30b are made of hydrophilic carbon fibers having a length of α or less and water-repellent carbon fibers having a length of 1 mm to 10 mm at a ratio of 1:10 to 3:10 and a carbon paper or carbon having a thickness α. It is felt. In this electrode, platinum or an alloy of platinum and another metal is supported as a catalyst on carbon powder, and the carbon powder is kneaded or applied in the gap between the carbon fibers. Here, the length of the hydrophilic carbon fibers, cathode
Since shorter than the thickness of the de 20b and anode 30b α,
The hydrophilic carbon fibers are present in any direction in the electrode. Therefore, it also exists in the thickness direction of the electrode. The water-repellent carbon fiber can be obtained by performing the same treatment as in the first embodiment.

Also in the cathode 20b and the anode 30b of the solid polymer electrolyte fuel cell of the third embodiment thus constituted, hydrogen and oxygen react according to the chemical reaction formula shown in formula (1), and the reaction energy (chemical energy) ) Is directly converted into electric energy.

The hydrophilic carbon fiber mixed in the cathode 20b is water produced in the catalyst (such as platinum) surface of the cathode 20b is guided to the flow path 42 removed from the vicinity of the catalyst. Especially caso
The hydrophilic carbon fibers located in the thickness direction of the cord 20b have a large water removal capacity. The water-repellent carbon fiber of the cathode 20b repels water from the periphery of the fiber and guides the oxygen-containing gas to the catalyst surface. On the other hand, the hydrophilic carbon fiber anode 30b is hydrogen ions shortfalls of water by moving in a hydrated state from the flow path 52 side surface of the anode 30b direct the water. In particular, the hydrophilic carbon fibers located in the thickness direction of the anode 30b have a large water supply capability. The water-repellent carbon fiber of the anode 30b guides hydrogen gas to the catalyst surface. By these actions, the cathode 20b and the anode
Reaction in de 30b is performed efficiently and continuously.

In the polymer electrolyte fuel cell of the third embodiment described above, the length of the hydrophilic carbon fiber forming the cathode 20b and the anode 30b is made shorter than the thickness of the electrode,
Since the carbon fibers also exist in the thickness direction, the water generated at the electrodes can be removed and the insufficient water can be replenished more smoothly. As a result, the vicinity of the catalyst surface is always kept in a good state, the water content of the electrolyte 10 is stabilized, the operating efficiency is improved, and stable power can be obtained.
Further, the carbon density is increased by mixing the carbon fiber shorter than the thickness of the electrode, so that the strength of the electrode is increased and the electrical conductivity is also improved.

Of course, since the cathode 20a and the anode 30a are formed by using the water-repellent carbon fiber, the fuel gas can be smoothly supplied. Also, the first
Similar to the example, even if the load current density is suddenly changed, the generated water is removed and the insufficient water is replenished smoothly, so that the water content of the electrolyte 10 becomes stable and the load current density is increased to increase the solid polymer fuel. The battery can be miniaturized. further,
Even if carbon paper or carbon felt is cut into an electrode, the cut portion does not fray, so that there is no need to treat the cut portion, and the manufacturing process can be simplified.

In the third embodiment, the ratio of the hydrophilic carbon fiber and the water repellent carbon fiber is set to 1:10 to 3:10, but
This ratio is determined by the type of battery, operating condition, etc., and can be various ratios according to the purpose of use. Further, in the third embodiment, the cathode 20b and the anode 30b are formed with the hydrophilic carbon fiber in an arbitrary direction, but a configuration in which the longitudinal direction of the hydrophilic carbon fiber is aligned with the thickness direction of the electrode is also suitable. In this case, the ability to remove generated water and the ability to replenish insufficient water are further improved,
It can be operated with high efficiency.

Although the polymer electrolyte fuel cell and the electrodes used in this cell have been described as an example of the embodiments of the present invention, various batteries such as a phosphoric acid fuel cell and an alkaline fuel cell and these cells can be used. It can also be carried out on the electrodes used. In addition, a device having the same structure as the fuel cell but having a reverse chemical reaction, for example, a so-called water electrolyzer or hydrogen generating device having the same structure as the polymer electrolyte fuel cell of the embodiment but having a reverse chemical reaction It can also be implemented in devices and the like and the electrodes used in these devices. Further, the electrode of the present invention is
Besides being used as an energy conversion device, it can also be used as an electrode of a device not intended for energy conversion or a device not performing energy conversion.

[0048]

As described above, in the first energy conversion device of the present invention, the electrode is formed by mixing the hydrophilic carbon fiber having hydrophilicity and the water repellent carbon fiber having water repellency. It is possible to smoothly remove the generated water in the vicinity of the electrode or supply the makeup water, and supply or remove the gas to the electrode. As a result, continuous and stable energy conversion can be performed.

[0049] In the second energy conversion device of the present invention, Ca
Hydrophilic carbon fibers having a hydrophilic based on electrochemical reaction at cathode and anode, so to form an electrode defining a ratio of the water-repellent carbon fiber having water repellency, Caso
The electrochemical reaction can be smoothly performed on the cathode and the anode , and continuous and stable energy conversion can be performed.

In the electrode of the present invention, since the electrode is formed by using the hydrophilic carbon fiber and the water repellent carbon fiber, the electrode can exhibit hydrophilicity and water repellency at the same time. That is, the hydrophilic carbon fibers can facilitate the removal of generated water or the supply of makeup water, and the water-repellent carbon fibers can facilitate the exclusion or supply of gas. In addition, since machining is not required after molding, manufacturing is easy and the cost can be reduced. Further, when the carbon cloth in which the hydrophilic carbon fiber and the water repellent carbon fiber are woven in a predetermined ratio is formed, it is possible to have both hydrophilicity and water repellency in the same process as the conventional manufacturing process. . If hydrophilic carbon fibers and water-repellent carbon fibers are mixed in a predetermined ratio to form carbon paper or carbon felt, it is possible to have both hydrophilicity and water repellency and directly form a free shape. can do.

[Brief description of drawings]

FIG. 1 is a schematic view of a cell structure of a polymer electrolyte fuel cell which is an embodiment of the present invention.

FIG. 2 is an enlarged explanatory view in which a part of a cathode 20 and an anode 30 is enlarged.

FIG. 3 is an enlarged explanatory diagram in which a part of a modified example of the cathode 20 and the anode 30 is enlarged.

FIG. 4 is an enlarged explanatory diagram in which a part of a modified example of the cathode 20 and the anode 30 is enlarged.

FIG. 5 is an explanatory diagram illustrating the configuration of warp yarns 22c and weft yarns 24c.

FIG. 6 is an explanatory diagram illustrating the configuration of the twisted yarn 28.

FIG. 7 is a cathode 20a and an anode 3 of the second embodiment.
It is explanatory drawing which illustrates the external appearance of 0a.

[Explanation of symbols]

10 ... Electrolyte 20, 20a, 20b ... Cathode 22, 22a, 22b, 22c ... Warp yarn 23 ... Hydrophilic carbon fiber 24, 24a, 24b, 24c ... weft 25 ... Water-repellent carbon fiber 28 ... twisted yarn 30, 30a, 30b ... Anode 40, 50 ... Gas flow channel structure 42, 52 ... flow path 60 ... Separator

Claims (5)

(57) [Claims] A cathode [1 claim], an anode, and an electrolyte, the energy conversion device that converts the chemical energy and electrical energy of a substance directly, at least one of the cathode or anode,
An energy conversion device comprising a mixture of hydrophilic carbon fibers having hydrophilicity and water-repellent carbon fibers having water repellency. 2. A cathode, an anode, and an electrolyte arranging between the both poles, the energy conversion device that converts the chemical energy and electrical energy of a substance directly, the cathode, hydrophilic carbon having a hydrophilic Fiber and water-repellent carbon fiber having water repellency are mixed and formed at a first ratio based on an electrochemical reaction in the cathode , and the anode has hydrophilic carbon fiber having hydrophilicity and water repellency. An energy conversion device characterized in that it is formed by mixing water-repellent carbon fibers in a second ratio based on an electrochemical reaction in the anode . 3. The energy according to claim 1 or 2.
A conversion device, wherein the cathode and the anode have a hydrophilic parent.
Prescribes water-based carbon fibers and water-repellent carbon fibers
Of carbon cloth, carbon paper or
An energy conversion device characterized by being formed as carbon felt . 4. Chemical energy and electric energy of a substance
An electrode used in an energy conversion device for direct conversion, the electrode being formed by mixing hydrophilic carbon fibers having hydrophilicity and water- repellent carbon fibers having water repellency in a predetermined ratio. 5. The electrode according to claim 4 , wherein the hydrophilic carbon fiber and the water-repellent carbon fiber are mixed in a predetermined ratio to form a carbon cloth, carbon paper or carbon felt.