JP2008174771A - Hydrogen storage device using solar power, method for forming hydrogen storage alloy electrode, and the hydrogen storage alloy electrode - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a shock-resistant, inexpensive, compact hydrogen storage device where, even if electrolysis is performed while directly dipping a hydrogen storage alloy electrode into an aqueous solution, oxidation is hard to occur, and occluded hydrogen is easy to be discharged, to provide a method for simply forming the hydrogen storage alloy electrode, and to provide the electrode formed thereby. <P>SOLUTION: The hydrogen storage device is characterized in that a solar power is used, the aqueous solution to be electrolyzed includes alkali metal, a hydrogen storage alloy electrode is incorporated in a cassette to which the aqueous solution can be charged/discharged, an alkali aqueous solution is generated by electrolysis, the inside of the cassette is provided with an alkaline substance, the electrolysis of the alkali aqueous solution can be maintained, and the cassette can be detached from the body. A solar battery panel is fitted with a float and a spindle, and it is floated on the sea, thus an electrolytic operation is made possible. Also disclosed is a hydrogen storage alloy electrode easily formed by a forming method including a removing stage for removing a coat material after an integration stage of compression/binding. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention electrolyzes an aqueous solution containing an alkali metal such as seawater with electric power from a solar cell to generate hydrogen while generating an alkaline aqueous solution, and this hydrogen is directly stored in a hydrogen storage alloy electrode as a negative electrode. Then, the present invention relates to a hydrogen storage device using photovoltaic power generation that can be used by releasing the hydrogen, a method of forming the hydrogen storage alloy electrode, and a hydrogen storage alloy electrode by this method.

By electrolyzing water and aqueous solutions, various industrial applications such as hydrogen production have been developed.

As a conventional method for producing hydrogen gas by electrolysis, an alkaline water electrolysis method or a method using a solar cell can be cited, and hydrogen is attracting attention as a clean new energy to replace fossil fuel.

However, since the conventional alkaline water electrolysis method uses existing energy such as petroleum and nuclear power for electrolysis, it is not desirable from the viewpoint of global environmental problems and energy problems in recent years. On the other hand, solar cells are expected as a clean hydrogen production method because they can convert natural light energy of sunlight into electric energy.

2. Description of the Related Art Conventionally, a fuel cell comprising a solar cell, a water electrolysis tank, a hydrogen storage means and an oxygen storage means for hydrogen and oxygen generated from the water electrolysis tank, and a fuel cell that operates with hydrogen and oxygen therefrom. There was a system (see Patent Document 1). In this hydrogen storage system, a hydrogen storage container containing a hydrogen storage alloy, a nonconductive container integrated with the hydrogen storage container, a heating device in which a coil for electromagnetic induction is disposed in the nonconductive container, The hydrogen storage container includes a cooling means for cooling the hydrogen storage alloy, and the hydrogen storage container has a structure that can be taken in and out of the non-conductive container, and can be transported by itself.

In addition, conventionally, it has at least a pair of electrodes at least partially immersed in the electrolyzed water, a solar cell, and a hydrogen storage alloy, and the electrolyzed water is electrolyzed by applying the output of the solar cell to each electrode. At the same time, there has been a CO ₂ refrigerant cycle device provided with a hydrogen generation and storage device that stores hydrogen generated by electrolysis in a hydrogen storage alloy (see Patent Document 2).

However, in the above examples, water is electrolyzed in a water electrolysis tank, and the generated hydrogen and oxygen gas is stored in a tank, and the hydrogen gas is stored in a hydrogen storage alloy in a gas state. The hydrogen storage alloy was not directly immersed in the water to be electrolyzed to store hydrogen by electrolysis. For this reason, there is a problem that the size of the tank becomes large, and circulation of hydrogen gas through a pipe is necessary, and the hydrogen pressure in the tank must be increased.

On the other hand, the applicant first used all or part of the negative electrode as a hydrogen storage electrode when electrolyzing an aqueous solution to generate hydrogen, and dipped it in the aqueous solution to be electrolyzed, It has been proposed to store hydrogen generated by decomposition directly into a hydrogen storage electrode (see Patent Document 3). In addition, in a solar cell that is used by generating electricity while immersing the positive electrode and negative electrode of the solar cell in an aqueous solution, a solar cell was proposed in which a float having a specific gravity smaller than that of the aqueous solution was provided on the substrate and floated on the electrolyzed water. (See Patent Document 4).

Conventionally, hydrogen storage alloy electrodes immersed in an alkaline solution have been activated by the development of nickel metal hydride batteries (see Patent Document 5). However, in the nickel metal hydride battery, hydrogen absorption and release are performed as charge and discharge of hydrogen ions in and out of a specific alkaline solution, whereas the hydrogen storage alloy electrode of the present invention is an electrolyte such as seawater. Therefore, it is only the operation of occlusion of hydrogen ions in the presence of various unspecified ions. Furthermore, regarding the release of hydrogen, it is taken out from an alkaline solution, heated release in gas or reduced pressure release, etc. It is to be released as hydrogen gas, and it is necessary to have an optimal structure for these.
JP-A-9-50820 JP 2006-46872 A JP 2002-170980 A JP 2004-281708 A JP 2002-42801 A

However, in the case of an ordinary solar cell, the obtained electromotive force must be guided to another electrode to be electrolyzed, so that connection wiring is necessary, and the fixing of the electrode is complicated and large. There is a problem of end.

Further, the hydrogen storage alloy is easily oxidized, and when immersed in an ordinary aqueous solution, the hydrogen storage alloy is oxidized and inactivated, so that there is a problem that hydrogen cannot be stored. For this reason, it was necessary to perform electrolysis in a strong alkaline aqueous solution.

In addition, when trying to install solar panels on land, they were exposed to storms and had to be fixed. Furthermore, securing a sunny land as a vast installation area is extremely limited and costly. On the other hand, the large sea having a large area is sunny and the solar panel that can be used by floating in the large sea requires very little installation cost and is very convenient.

In the present invention, the power of the solar cell was connected to the negative electrode, for example, Mm (La, Ce, Nd , Pr) -Ni system, _{Ti-Ni-based, Ti-NiZr (Ti 2-} x Zr x V 4-y Ni _y ) Electrolysis while directly immersing a hydrogen storage alloy electrode using a hydrogen storage alloy such as _1-z Cr _{z in an} aqueous solution to generate hydrogen and prevent the hydrogen storage alloy from being oxidized. In addition to providing a structure that makes it easy to take out the stored hydrogen, and also to provide a hydrogen storage device that uses a small-sized solar power generation that has a structure that can withstand being exposed to storms, it is easy to use a hydrogen storage alloy electrode that is used therefor. It is an object to provide a forming method and a hydrogen storage alloy electrode by the method.

In order to achieve the above object, a hydrogen storage device using solar power generation according to claim 1 of the present invention electrolyzes an aqueous solution using the power of a solar cell, and stores the generated hydrogen in a hydrogen storage alloy electrode. In the hydrogen storage device, the negative electrode of the solar cell is connected to the hydrogen storage alloy electrode, and this hydrogen storage alloy electrode is used as at least a part of the negative electrode material when electrolyzing and soaks in the aqueous solution to be electrolyzed. The aqueous solution to be electrolyzed is an aqueous solution containing an alkali metal, an alkaline aqueous solution is generated by electrolysis of the aqueous solution, and the hydrogen storage alloy electrode is immersed in the alkaline aqueous solution. It is characterized in that it is built in a cassette that allows an electrolyzed aqueous solution to enter and exit, and that this cassette is removable from the hydrogen storage device. In the is.

When the hydrogen storage alloy electrode is exposed to a normal aqueous solution, it is immediately oxidized and deactivated, making it impossible to store hydrogen. Therefore, for example, in a nickel metal hydride fuel cell, a hydrogen storage alloy electrode is always immersed in an alkaline aqueous solution. For this reason, the present invention utilizes the fact that a strong alkaline aqueous solution is formed near the negative electrode when an aqueous solution containing an alkali metal is electrolyzed even if it is neutral, such as seawater or saline. In addition, the hydrogen storage alloy electrode is not easily oxidized.

Further, in the present invention, the hydrogen storage alloy electrode is built in the cassette that allows the electrolytic solution to enter and exit, and is electrically connected to the negative electrode of the solar cell, and the hydrogen storage alloy electrode itself also acts as the negative electrode. For this reason, the strong alkaline aqueous solution generated in the vicinity has a structure that is difficult to escape due to diffusion or the like.

In the present invention, the hydrogen storage alloy electrode is incorporated into the cassette so that it can be detached from the hydrogen storage device. After that, the cassette is transported to a predetermined facility where the stored hydrogen is heated. It can be taken out as hydrogen gas.

The hydrogen storage device using solar power generation according to claim 2 of the present invention is a case where the solar cell, the positive electrode and the cassette holder to which the cassette is mounted have an integrated structure. The hydrogen storage device using photovoltaic power generation according to the present invention is mainly assumed to be used by floating this device in the sea. Therefore, a compact structure that can withstand storms is required. It is done. Therefore, the structure is integrated as much as possible.

The hydrogen storage device using photovoltaic power generation according to claim 3 of the present invention is such that the aqueous solution to be electrolyzed is an aqueous solution in which an alkali metal chloride is dissolved. For example, when using a saline solution containing. Of course, the aqueous electrolytic solution may be an alkaline aqueous solution containing an alkali metal.

The hydrogen storage device using photovoltaic power generation according to claim 4 of the present invention is a case where an alkaline substance is provided in the cassette and the oxidation of the hydrogen storage alloy electrode is prevented when immersed in an aqueous solution to be electrolyzed. . As described above, when the hydrogen storage alloy electrode is exposed to normal water, it immediately oxidizes and is inactivated, making it impossible to store hydrogen. Therefore, it is inactivated when exposed to water such as neutral seawater, so that an alkaline substance is provided in the cassette so that when a hydrogen storage alloy electrode is immersed in seawater, it becomes a strong alkaline aqueous solution immediately. This is the case.

There are various methods for providing an alkaline substance in the cassette. For example, a storage place such as sodium hydroxide (NaOH) or potassium hydroxide (KOH) is formed at a specific place in the cassette. When immersed in an aqueous solution to be electrolyzed, it may be dissolved therein to make the inside of the cassette a strong alkaline aqueous solution, or rather, an alkaline substance may be provided at a specific location in the hydrogen storage alloy electrode. Alternatively, it may be soaked in a concentrated alkaline aqueous solution, and then sodium hydroxide or the like dissolved by drying may be left in the pores of the hydrogen storage alloy electrode.

The hydrogen storage device using solar power generation according to claim 5 of the present invention is a case where a structure including a weight and a float and floating on an aqueous solution to be electrolyzed is provided. It is assumed that the solar cell is made into a panel shape and floated on an electrolyzed aqueous solution such as seawater. In this case, the panel-like solar cell receives a light from the sun with its face on the seawater. There is a need for a structure that can be stably held by weights and floats against storms. In the present invention, apart from the arrangement of weights and floats, the panel-like solar cell may cover some seawater, but usually the light-receiving part of the solar cell faces the seawater and emits light from the sun. This is the case where the structure can receive light.

In order to achieve a hydrogen storage device that is as compact and inexpensive as possible, the hydrogen storage device using photovoltaic power generation according to claim 6 of the present invention is a case where the weight is mainly composed of a cassette containing a hydrogen storage alloy electrode. This is a case where the majority of the weight is structured to be a cassette containing a hydrogen storage alloy electrode. Of course, it may be better to have a structure in which a weight other than the cassette is further hung down in order to ensure further stability in operating the hydrogen storage device floating on the sea.

The hydrogen storage device using solar power generation according to claim 7 of the present invention is a case where a carbon-based material is used for the positive electrode in the portion immersed in the aqueous solution to be electrolyzed. According to the experimental results, it was confirmed that even when platinum or gold was used for the positive electrode, it was etched during electrolysis. It has been confirmed that the carbon electrode operates stably although the electrolysis voltage increases. Examples of the carbon-based material include carbon fiber, a material in which this is woven, and a rubber-based material and a plastic material that contain a large amount of carbon black and ensure conductivity.

The method for forming a hydrogen storage alloy electrode according to claim 8 of the present invention is a method for forming a hydrogen storage alloy electrode, wherein a conductive material is plated on the surface of a powdered hydrogen storage alloy which is a raw material constituting the hydrogen storage alloy electrode. A coating process for coating with, etc., an integration process in which the powdered hydrogen storage alloy that has undergone this coating process is compressed and bonded and integrated via a coating material of this conductive material, and after this integration process, the coating material And a step of removing the conductive material for chemically removing a part of the surface and exposing at least a part of the surface of the powdered hydrogen storage alloy bonded thereto. However, if the coating material is conductive rubber or plastic, the process proceeds to the integration process as it is, so the coating process is not film formation, and after the subsequent integration process, the surfaces of the powdered hydrogen storage alloy are mutually attached. A film is formed to be bound.

The features and objects of the method for forming the hydrogen storage alloy electrode of the present invention can be further explained as follows. First, as a coating process, the surface of the powdered hydrogen storage alloy is made of a coating material, which is a conductive material, and coatings each having a thickness of at least several micrometers are formed together by electroless plating or coating, or conductive. In the case of rubbers or plastics, these are mixed with these powders or dissolved with a solvent and mixed with a powdered hydrogen storage alloy. After that, this is compressed in a pressing or rolling compression process, and a powdered hydrogen storage alloy is bound using the coating material as an adhesive layer. In the integration process using the press, an electrode having a predetermined shape is formed. The powdered hydrogen storage alloy that has undergone the coating process is placed in the mold and compressed. In addition, the powdered hydrogen storage alloy that has undergone the coating process on the rolled substrate, or the powdered hydrogen storage alloy that has been mixed with conductive rubber, etc. also serves as the coating process, and the integration process is performed by compression by rolling. Do. A coating material is used with the adhesive layer for binding as a binding material. Accordingly, the coating material needs to have conductivity for use as a hydrogen storage alloy electrode, and heat resistance is required because hydrogen is taken out as a gas at a high temperature of 100 ° C. or higher. Furthermore, since the hydrogen storage alloy electrode is used as a negative electrode for solar cells, it is always at a negative potential, so it does not dissolve in the aqueous solution to be electrolyzed. May be used as a coating material. However, when the electrode wiring is cut off, it is exposed to the aqueous electrolytic solution of the alkaline aqueous solution, so that an alkali resistant material such as nickel (Ni) is desirable as much as possible.

Next, the portion of the porous hydrogen storage alloy electrode that is exposed to the electrolyzed aqueous solution should be exposed to the hydrogen storage alloy. Therefore, the portions other than the portions where the powdered hydrogen storage alloys are strongly bonded in the compression step remain. In the removal process that removes the surface coating material by chemical reaction such as etching or elution with a solvent, the integrated porous porous surface has hydrogen storage of each particle of the original powdered hydrogen storage alloy A hydrogen storage alloy electrode in which the alloy is exposed is produced.

When nickel (Ni) is used as the coating material, the powdered hydrogen storage alloy may be treated with an electroless nickel plating solution and plated to a thickness of about 5 microns, or carbon black may be mixed with rubber or plastic. It is also possible to use a material whose conductivity is increased. When nickel (Ni) is used, the surface of fine particles of the powdered hydrogen storage alloy removes strongly bonded parts by infiltrating weak acid such as dilute nitric acid from the porous part of the porous hydrogen storage alloy electrode in the removal process. The coating material can be removed by chemical etching to expose the surface of the powdered hydrogen storage alloy. In this way, the occlusion of hydrogen by electrolysis can be facilitated. The same can be applied to other metal plating. In addition, carbon black was mixed with the above rubber and plastic, and the coating material was allowed to penetrate the porous portion of the porous hydrogen storage alloy electrode by removing the rubber or plastic solvent, and similarly removed the strongly bonded portion. Part of rubber and plastic can be dissolved to expose the surface of the powdered hydrogen storage alloy.

In the compression process, the powdered hydrogen storage alloy coated with the coating material after the coating process may be combined with a press to form a predetermined shape, but it may be a foil such as steel or nickel, a roller on a plate-shaped rolling substrate, etc. May be rolled. If the rolled substrate is eroded by an alkaline solution, the surface should be coated with an alkaline solution material and a conductive material (eg nickel) that can withstand the high temperatures used for hydrogen release. good. This may be sent to the next removal step and wound or overlapped to form a porous hydrogen storage alloy electrode having a predetermined size.

A hydrogen storage alloy electrode according to claim 9 of the present invention is formed by the forming method according to claim 8.

Since the hydrogen storage device using photovoltaic power generation of the present invention uses an aqueous solution containing an alkali metal as an aqueous solution to be electrolyzed, a strong alkaline aqueous solution such as an aqueous sodium hydroxide solution is generated near the negative electrode. There is an advantage that the alloy electrode can occlude hydrogen without being oxidized.

In the hydrogen storage device using solar power generation according to the present invention, even when the aqueous solution to be electrolyzed is neutral like seawater, the cassette containing the hydrogen storage alloy electrode is provided with an alkaline substance and immersed in the aqueous solution to be electrolyzed. Occasionally, the alkaline substance dissolves into a strong alkaline aqueous solution, which has the advantage that the hydrogen storage alloy electrode can be prevented from being oxidized and inactivated. Once electrolysis starts, a strong alkaline aqueous solution is generated and replenished in the vicinity of the negative electrode where the hydrogen storage alloy electrode is present as described above, so that inactivation can be continuously prevented in subsequent electrolysis. .

For example, since the seawater is electrolyzed by floating on the sea using the power of the solar cell, hydrogen can be taken out as an inexhaustible energy source and can be used as a clean energy source even if hydrogen is burned. . In addition, for example, when used floating in the sea, the solar cell panel can be restored with a weight and a float so that it can receive sunlight even if it is shaken by being exposed to storms. It can be used with various devices.

Since a cassette containing a hydrogen storage alloy electrode as a weight can be mainly used, it can be a compact hydrogen storage device.

The cassette holder for mounting the solar cell, the positive electrode and the cassette has an integrated structure, so that it is a compact device that can easily be coated to prevent corrosion even when immersed in seawater. There are advantages. In addition, even if it is an integrated structure, the structure which can be disassembled with a screw etc. for the purpose of repair etc. is desirable.

The hydrogen storage alloy electrode is built in a cassette that allows the electrolytic solution to enter and exit. Further, since this cassette is detachable from the hydrogen storage device, the cassette can be easily removed and the specified equipment is installed. There is an advantage that hydrogen can be taken out by transporting it to a certain place and heating a cassette containing a hydrogen storage alloy electrode. In addition, the place with the predetermined equipment may be a special facility, or may be an automobile that uses hydrogen as a fuel.

After removing the cassette containing the hydrogen storage alloy electrode that has stored hydrogen from the hydrogen storage device, it can be replaced on the spot with a cassette containing another hydrogen storage alloy electrode that has not yet stored hydrogen. There is an advantage that the hydrogen storage device can be operated.

In the above description, it has been described that it is used floating in the sea. For example, it is floated in a salt water tank or water tank as an aqueous solution in which an alkali metal chloride is dissolved in a factory or household, and the power of the solar cell Since hydrogen can be taken out by using this, there is an advantage that the production of clean energy can be dispersed.

Since the carbon-based material is used for the positive electrode immersed in the aqueous solution to be electrolyzed, there is an advantage that a stable and durable hydrogen storage device can be provided.

In the method for forming a hydrogen storage alloy electrode of the present invention, the conductive material can be coated on the surface of the powdered hydrogen storage alloy, and the porous material is compressed in the compression process. In addition, there is an advantage that the surface of the powdered hydrogen storage alloy in direct contact with the aqueous solution to be electrolyzed can be easily exposed by injecting and removing the solvent.

In the method of forming a hydrogen storage alloy electrode of the present invention, when a coating process such as a metal plating film is performed as a coating material, after the integration process of compression, there is a gap in the bound powdered hydrogen storage alloy. The coating material etchant can easily enter, and in other coating processes, the solvent of the coating material can be injected to remove the coating material, except for strongly bonded parts. A hydrogen storage alloy electrode is formed which is shaped into a specific shape by the quality and exposes the respective surfaces of the powdered hydrogen storage alloy. However, when the hydrogen storage device using photovoltaic power generation is actually floated on the sea to electrolyze the seawater and store the hydrogen in the hydrogen storage alloy electrode, the exposed surface of the powdered hydrogen storage alloy part of the hydrogen storage alloy electrode In addition, other positive ion metals and molecules contained in seawater are plated, bacterial growth and contamination are caused, which hinders hydrogen storage. Therefore, it is necessary to regenerate the hydrogen storage alloy electrode after hydrogen is released as a gas and taken out. For this purpose, using the porous hydrogen storage alloy electrode described above, there is an advantage that it can be regenerated by being washed and removed with an acid, an aqueous alkali solution, or a solvent through the pores.

  Hereinafter, a hydrogen storage device using solar power generation according to the present invention will be described in detail based on examples with reference to the drawings.

  FIG. 1 is a schematic cross-sectional view showing an embodiment of a hydrogen storage device using solar power generation according to the present invention, and shows a state when floating on the sea. It floats in the sea by the float 9, and the cassette 3 containing the hydrogen storage alloy electrode 2 is the main body of the weight 8, so it is electrically connected to the negative electrode 5 of the solar cell 1 via the negative electrode 15. The hydrogen storage alloy electrode 2 and the positive electrode 14 electrically connected to the positive electrode 4 of the solar cell 1 are always immersed in seawater which is an aqueous solution to be electrolyzed. The solar cell 1 is in the form of a panel, and the light receiving unit 101 appears to have a face in the atmosphere with the sun. In this embodiment, the weight 8 has a structure mainly composed of a detachable cassette 3 (see FIG. 3) in which the hydrogen storage alloy electrode 2 is incorporated.

FIG. 2 shows a part of the hydrogen storage device using solar power generation according to the present invention in which the solar cell when the cassette 3 shown in FIG. 3 is removed and the cassette holder for mounting the positive electrode and the cassette are integrated. 1 is a schematic cross-sectional view of an embodiment (hereinafter referred to as a main body). FIG. 3 shows a schematic cross-sectional view of one embodiment of the removable cassette 3, and shows a state in which the hydrogen storage alloy electrode 2 is mounted inside the cassette 3.

The outline of the structure of the hydrogen storage device using solar power generation according to the present invention will be described as follows. The structure of the main body in which the light receiving part 101 of the panel-shaped solar cell 1 is integrated with the cassette holder 23 for supporting the cassette 9 containing the floating 9 and the hydrogen storage alloy electrode 2 via the support plate 10. It has become. The state of this body is shown in FIG.

The present embodiment assumes a case where a hydrogen storage device using solar power generation is floated on the sea and seawater is used as an electrolyzed aqueous solution. The panel-like solar cell 1 of the hydrogen storage device using photovoltaic power generation is designed to balance well between the weight 8 and the float 9, and the hydrogen storage device floating in the sea is exposed to storms Even if it repeats, it has designed so that the light-receiving part 101 of the panel-shaped solar cell 1 may come out to the sea surface again, and can receive sunlight.

The operation of the present invention will be described with reference to FIG. The electrolyzed aqueous solution that is seawater is electrolyzed by the electric power generated by the panel-like solar cell 1. Originally, the voltage required for the electrolysis of water is 2.1 V, but it is better that the voltage is 6 V or more in consideration of various voltage drops such as electrode drops. The positive electrode 4 of the solar cell and the negative electrode 5 of the solar cell are formed on the panel of the solar cell 1, and the positive electrode conductor 24 and the negative electrode conductor 25 are embedded in the electrically insulating support plate 10. These are connected to a carbon-based positive electrode 14 and a negative electrode 15, respectively. The positive electrode 14 is immersed in seawater, which is an aqueous solution to be electrolyzed, but the negative electrode 15 is electrically connected to the hydrogen storage alloy electrode 2 built in the cassette 3 used as a part of the negative electrode 15. Yes. The cassette 3 is fastened to the main body with a screw structure or the like so that it can be detached from the main body. Also, the cassette 3 is provided with a storage box 7 for alkaline substances. When the cassette 3 is first immersed in seawater, the alkaline substance 6 such as sodium hydroxide provided therein dissolves in the seawater and melts into the hydrogen storage alloy. The electrode 2 is made a strong alkaline aqueous solution. Thereby, the inactivation by the oxidation etc. of the hydrogen storage alloy electrode 2 can be prevented. In addition, the cassette 3 is made of a porous material so that seawater can enter and exit the cassette 3, or a hole is made, and the alkaline material storage box 7 is also made of a porous material so that seawater can easily enter and exit. , I try to keep a hole. Thus, the cassette 3 is made of a porous material so as to take a role of a filter such as dust in seawater.

When seawater electrolysis starts with the electric power of the solar cell 1, the hydrogen storage alloy electrode 2 used as a part of the negative electrode 15 undergoes electrolysis of an alkaline aqueous solution to generate hydrogen. In many cases, hydrogen that has been positively ionized without becoming hydrogen gas is directly taken into the hydrogen storage alloy electrode 2. However, since a part is released as hydrogen gas, the internal pressure of the cassette 3 increases. Although it is advantageous to store hydrogen in the hydrogen storage alloy electrode 2 when the internal pressure is high to some extent, a pressure balance hole 110 is provided in order to prevent the entry and exit of seawater and the cassette 3 from bursting. ing.

The material of the cassette 3 and the support plate 10 is more conveniently an electrically insulating material. However, when a conductor such as a metal is used, at least a portion in contact with the electrode is coated with an electrically insulating material. It is necessary to prevent a short circuit between the positive and negative electrodes of the solar cell 1.

The cassette cap 13 which is a part of the cassette 3 is fastened to the cassette 3 with screws or the like, for example, and the hydrogen storage alloy electrode 2 can be detached by removing the cassette cap 13. Further, the cassette cap 13 is provided with an alkaline substance insertion port 17 so that the alkaline substance 6 such as sodium hydroxide can be inserted many times, and the lid is covered with the stopper 107.

The positive electrode 14 mainly generates chlorine gas in the case of seawater. In the present embodiment, the generated gas such as the generated chlorine gas is released to the outside through a gap in the positive electrode 14 or, if necessary, through a hole provided in the positive electrode 14. Of course, the gas generated at the positive electrode 14 may be collected and used.

The positive electrode 14 is made of, for example, a conductive rubber material in which carbon fiber is woven and further mixed with carbon black so that the conductive carbon fiber or carbon black is in direct contact with seawater as an electrolysis solution. Yes. This can be constructed to withstand shocks even if the hydrogen storage devices collide with each other when they float in the ocean and are exposed to storms. Of course, although not adopted here, the periphery of the positive electrode 14 may be further surrounded by a plate of metal or the like and provided as a guard plate. In view of repair, repair and regeneration, it is better to have a structure that can be removed and disassembled.

FIG. 4 is a schematic diagram showing each process of forming a hydrogen storage alloy electrode with the powdered hydrogen storage alloy 20 as a nucleus for explaining the respective steps of manufacture, with respect to the method for forming a hydrogen storage alloy electrode of the present invention. It is. In FIG. 4A, for example, fine particles of a powdered hydrogen storage alloy 20 containing nickel (Ni) having a particle diameter of 200 micrometers are depicted. FIG. 4B shows a state in which the surface of the powdered hydrogen storage alloy 20 is uniformly plated with a thickness of about 5 micrometers by electroless plating of nickel (Ni) as the coating material 201. This is the coating process. FIG. 4 (c) shows a state in which after the coating process is finished, the powdered hydrogen storage alloy is pressed and shaped into a predetermined shape by a press, and the powdered hydrogen storage alloy that has been subjected to the coating process is compressed and integrated through the coating material 201. It is the schematic which drawn the condition after the integration process. In this case, the coating material 201 serves as an adhesive that bonds the powdered hydrogen storage alloys together. In FIG. 4 (d), after the integration step, the coating material 201 is removed by etching using the porosity, except for the coating material binding portion 202, which is soaked in dilute nitric acid through the porosity and strongly bonded. The coating material removal part 210 is formed and at least a part of the surface of the bound powdered hydrogen storage alloy is exposed. This process is a removal process.

FIG. 5 shows a flow chart of the characteristic steps of the method for forming the hydrogen storage alloy electrode of the present invention. Here, a powdered hydrogen storage alloy 20 is prepared, and this is flowed in the order of a coating process, an integration process, and a removal process, and a flow chart of a process for finally producing a hydrogen storage alloy electrode is shown as a block diagram. .

In the method for forming a hydrogen storage alloy electrode according to the present invention, a powdered hydrogen storage alloy 20 is prepared, and this is passed through a coating process, an integration process, and a removal process in this order to finally produce a hydrogen storage alloy electrode. However, FIG. 6 shows an embodiment of the hydrogen storage alloy electrode according to the present invention. The integration process in the method for forming the hydrogen storage alloy electrode of the present invention is performed by applying a coating process to a mold of a predetermined size. FIG. 2 is a schematic view of an embodiment of the hydrogen storage alloy electrode 2 in which the powdered hydrogen storage alloy 20 is put and compressed by a press to be bonded and integrated. In the drawing, the particles of the powdered hydrogen storage alloy 20 are exaggerated and drawn greatly. For example, the longitudinal dimension of the substantially cuboid hydrogen storage alloy electrode 2 is about 20 cm. For example, a nickel plating layer is used as the coating material 201.

FIG. 7 shows another embodiment of the hydrogen storage alloy electrode according to the present invention. In FIG. 6 in the case of the example 4 described above, the powdered hydrogen storage alloy 20 that has been subjected to the coating process is put and compressed by a press to be integrated and integrated into an integrated process. In FIG. 7, for example, a nickel-plated steel plate is used as a rolled substrate 150, and the powdered hydrogen storage alloy 20 that has undergone the coating process is applied to both the front and back surfaces, for example, viscosity adjustment liquid or liquid adhesive is adjusted in viscosity. It is applied while adjusting the viscosity, for example, by mixing the powdered hydrogen storage alloy 20 before the coating process with the coating process, for example, mixing carbon black or the like with a rubber-based liquid. A plate-shaped hydrogen storage alloy electrode 2 is shown in which the sheet is rolled and compressed with a roller and bonded and integrated. Of course, the viscosity adjusting liquid can be removed simply by heating the viscosity adjusting liquid. However, in the step of removing the coating material 201, the coating material binding portion of the coating material 201 using an organic solvent or the like of the coating material 201 is used. The coating material removing portion 210 can be formed by elution leaving 202.

FIG. 8 shows another embodiment of the form of the hydrogen storage alloy electrode of the present invention, in which the plate-shaped hydrogen storage alloy electrode 2 produced in FIG. In this example, the wound type hydrogen storage alloy electrode 2 is used. The rolled rolled substrate 150 can be joined to another electrode plate to form a negative electrode 15 collectively like one electrode of a conventional wound capacitor element. This is advantageous because it is compact and the resistance of the electrode is reduced.

Although not shown as an example, as the coating material 201, as described above, for example, a material in which carbon black is mixed with rubber or plastic to increase conductivity may be used. In the removing step, the coating material 201 except the coating material binding portion 202 is removed by impregnation with a rubber or plastic solvent to form the coating material removal portion 210, and the bound powdered hydrogen It is also possible to expose at least part of the surface of the storage alloy.

In general, the hydrogen storage alloy expands in volume when it stores hydrogen, so it easily breaks and is preferably in powder form from the beginning. Further, the hydrogen storage alloy electrode 2 also has a porous material including the coating material removal portion 210 and the selection and thickness of the material so that the coating material binding portion 202 is flexible so that it can withstand internal stress associated with storage and release of hydrogen. It is desirable to increase the ratio.

  The hydrogen storage device using photovoltaic power generation of the present invention is mainly assumed to be used by floating in the ocean. Therefore, there is a need for a structure that is as compact as possible and that can withstand storms. The solar cell is made into a panel shape and the power is used. The negative electrode of the solar cell is used as a hydrogen storage alloy electrode. It is directly immersed in seawater as an aqueous solution to be electrolyzed. This is a hydrogen storage device that directly stores in an electrode. In general, hydrogen storage alloys are oxidized only when they are not alkaline aqueous solutions, so the seawater is also devised so that it becomes an alkaline aqueous solution from the beginning. It is also characterized in that an alkaline aqueous solution is continuously electrolyzed even when electrolysis is performed. In addition, this hydrogen storage alloy electrode is built in a cassette that allows the electrolytic solution to enter and exit, and since this cassette can be detached from the hydrogen storage device, a hydrogen storage alloy electrode that stores hydrogen The cassette with built-in can be transported to facilities and places where hydrogen is released as hydrogen gas. The place where the hydrogen gas is taken out from the hydrogen storage alloy electrode may be an automobile, in which the hydrogen gas can be used as a fuel or can be used as a fuel cell. Various methods for extracting hydrogen gas from the hydrogen storage alloy electrode are conceivable, but it would be optimal to heat the hydrogen storage alloy electrode. The hydrogen-absorbing alloy electrode from which hydrogen has been released can be regenerated and reused by removing a plating film or contaminants of various ions in the seawater adhering to the surface.

In recent years, since many hydrogen storage alloys have been developed and are commercially available, powdered hydrogen storage alloys can be obtained easily and inexpensively, and a hydrogen storage device using inexpensive solar power generation can be provided.

It is a cross-sectional schematic diagram which shows one Example of the hydrogen storage apparatus using the photovoltaic power generation of this invention. (Example 1) 1 is a schematic cross-sectional view showing an embodiment of a part (main body) of a hydrogen storage device using solar power generation according to the present invention. (Example 1) It is the cross-sectional schematic which shows one Example of the cassette which can attach or detach the hydrogen storage apparatus using the solar power generation of this invention. (Example 1) It is the schematic which showed each process of forming a hydrogen storage alloy electrode by making the powdered hydrogen storage alloy 20 into a nucleus for explaining each process of manufacture regarding the formation method of the hydrogen storage alloy electrode of this invention. (Example 2) The flowchart of the characteristic process of the formation method of the hydrogen storage alloy electrode of this invention is shown. (Example 3) An example of the form of the hydrogen storage alloy electrode of the present invention is shown. Example 4 Another example of the form of the hydrogen storage alloy electrode of the present invention is shown. (Example 5) Another Example of the form of the hydrogen storage alloy electrode of invention is shown. (Example 6)

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Solar cell 2 Hydrogen storage alloy electrode 3 Cassette 4 Solar cell positive electrode 5 Solar cell negative electrode 6 Alkaline substance 7 Alkaline substance storage box 8 Weight 9 Floating plate 10 Support plate 13 Cassette cap 14 Positive electrode 15 Negative electrode 17 Alkaline substance insertion port 20 Powdered hydrogen storage alloy 23 Cassette holder 24 Positive electrode conductor 25 Negative electrode conductor 101 Light receiving portion 107 Plug 20
110 Pressure balance hole 150 Rolled substrate 201 Coat material 202 Coat material binding part 210 Coat material removing part

Claims (9)

In a hydrogen storage device that uses solar power to electrolyze an aqueous solution using the power of a solar cell and store the hydrogen generated at that time in a hydrogen storage alloy electrode, the negative electrode of the solar cell is connected to the hydrogen storage alloy electrode. The hydrogen storage alloy electrode is used as at least a part of a negative electrode material when electrolyzing and is immersed in an aqueous solution to be electrolyzed, the aqueous solution to be electrolyzed is an aqueous solution containing an alkali metal, An alkaline aqueous solution is generated by electrolysis of the aqueous solution, and the hydrogen storage alloy electrode is immersed in the alkaline aqueous solution; the hydrogen storage alloy electrode is built in a cassette that allows the aqueous solution to be electrolyzed; The hydrogen storage device using photovoltaic power generation, wherein the cassette is detachable from the hydrogen storage device. The hydrogen storage device using solar power generation according to claim 1, wherein the solar battery, the positive electrode, and the cassette holder on which the cassette is mounted have an integrated structure. The hydrogen storage device using photovoltaic power generation according to claim 1 or 2, wherein the aqueous solution to be electrolyzed is an aqueous solution in which an alkali metal chloride is dissolved. The hydrogen storage device using photovoltaic power generation according to any one of claims 1 to 3, wherein an alkaline substance is provided in the cassette and the oxidation of the hydrogen storage alloy electrode is prevented when immersed in an aqueous solution to be electrolyzed. The hydrogen storage device using solar power generation according to any one of claims 1 to 4, wherein the hydrogen storage device includes a weight and a float, and is structured to float on an aqueous solution to be electrolyzed. The hydrogen storage device using solar power generation according to claim 5, wherein the weight is mainly a cassette containing a hydrogen storage alloy electrode. The hydrogen storage device using solar power generation according to any one of claims 1 to 6, wherein a carbon-based material is used for a positive electrode in a portion immersed in the aqueous solution. A method for forming a hydrogen storage alloy electrode, comprising: a coating step of coating a conductive material on the surface of a powdered hydrogen storage alloy which is a raw material constituting the hydrogen storage alloy electrode; and compressing the powdered hydrogen storage alloy after the coating step. Then, an integration step of binding and integrating through the coating material which is the conductive material, and after the integration step, a part of the coating material is chemically removed and bonded to form a powdered hydrogen storage alloy A method for forming a hydrogen-absorbing alloy electrode, comprising the step of removing a coating material for exposing at least a part of the surface of the electrode. A hydrogen storage alloy electrode formed by the forming method according to claim 8.

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