JPH07122305A - Sealed light oxygen secondary battery - Google Patents

Abstract

PURPOSE:To provide a two electrode system sealed light oxygen secondary battery capable of charging. CONSTITUTION:A positive electrode 21 made of an oxygen catalyst, a negative electrode 22 made of a metallic negative electrode member 22a, an electrolyte 23 in contact with the positive electrode 21 and the negative electrode 22, and a battery case 27 into which the positive electrode 21, the negative electrode 22, and the electrolyte 23 are accommodated are arranged. A light receptor 27a from which rays enters the negative electrode member 22a is installed in the battery case 27. The electrolyte 23 is absorbed and held in a porous body 24. A battery is discharged with the oxidation reaction of the negative electrode member 22a and the reduction reaction of oxygen. By exposing the discharge product on the negative electrode member 22a to light energy, the discharge product is reduced, and at the same time oxygen is produced for charging. A charger is unnecessary because charge is conducted by light. Battery structure is simplified in two electrode system of the positive electrode and the negative electrode.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rechargeable battery capable of both charging and discharging, which can be charged by light energy and does not require a charger. It relates to the next battery.

[0002]

2. Description of the Related Art Attempts have been made to generate electricity by utilizing the redox reaction of oxygen generated by light energy such as visible light from the sun. As shown in FIG. -A-4042758 photochemical cell is known. Here, reference numeral 1 is a photochemical cell, and this photochemical cell 1 is
It has a pipe-shaped eugometer 2, and a pipe-shaped right arm 3 and a left arm 4 which are arranged in parallel with each other around the eugometer 2. The interiors of the eugeometer 2, the right arm 3, and the left arm 4 communicate with each other.

The right arm 3 and the left arm 4 are provided with upper stoppers 3a, 4a and lower stoppers 3b, 4b for sealing them. The right arm 3 and the left arm 4 are connected by a bridge 5 that connects them. A central valve 2a is formed on the upper part of the eugeometer 2 and a lower part thereof is connected to the bridge 5. The right arm 3, the left arm 4, and the bridge 5 are filled with an electrolyte 6.

In addition, the light arm 3 has air 1 above it.
0 is filled, the lower part is filled with the electrolyte 6, and the anode 7 is arranged in the electrolyte 6. On the other hand, the left arm 4 is filled with air 11 in the upper part and the electrolyte 6 in the lower part.
And the cathode 8 is disposed across the air 11 and the electrolyte 6. Conductors 7a and 8a are connected to the anode 7 and the cathode 8, respectively, and the conductors 7a and 8a are connected to each other via a load 9.

A light source 12 for irradiating the anode 7 with light
Is installed adjacent to the outside of the light arm 3.
The light source 12 includes a mercury lamp 13 and the mercury lamp 1.
And a lens 14 for focusing the light of No. 3 and irradiating it to the anode 7. In such a photochemical cell 10, oxygen is generated by irradiating the anode 7 having titanium dioxide formed on its surface with light energy. By guiding this oxygen from the anode 7 to the platinum cathode 8 and reducing it, the light energy is electrochemically converted into electric energy.

[0006]

However, in the conventional photochemical cell, since the power is generated only while the light energy is being irradiated, the light energy storage function, that is,
It has a drawback that it has no secondary battery function and can be discharged only under light irradiation. In addition, the conversion of light energy into electrochemical energy requires an anode 7 made of a relatively expensive semiconductor material. Without this anode 7, photo-charging cannot be performed and there is a problem that it does not function as a photovoltaic cell. It was Further, in order to discharge a relatively large current, it is necessary to quickly move oxygen generated in the anode 7 to the cathode 8. However, in the conventional photochemical cell, the moving speed of oxygen in the electrolyte 6 is slow. However, there is a drawback that a large current cannot be discharged.

A conventional photochemical cell is composed of a two-electrode system consisting of two electrodes, an anode 7 functioning as a photoelectrode for generating oxygen by light energy, and a cathode 8 for reducing oxygen. It Since this conventional photochemical cell does not have a function as a secondary cell, there is no problem even if it is configured with a two-electrode system. However, in order to realize a photochemical secondary battery having a secondary battery function (light energy storage function), a positive electrode and a negative electrode for performing a so-called discharge reaction, and a charging reaction by electrochemically converting light energy are performed. A photoelectrode is required to advance.
Therefore, at least three or more electrodes of the positive electrode, the negative electrode, and the photoelectrode are required, and this photochemical secondary battery must be configured with a system of three electrodes or more, which complicates the structure of the photochemical secondary battery. There was a drawback.

The present invention has been made in view of the above circumstances, and provides a photo-oxygen secondary battery which can store light energy, that is, can be charged by light energy and which does not require a charger and is excellent in energy saving. To provide. In particular, the main focus is on a simple structure consisting of a semiconductor and a two-electrode system that does not require a photoelectrode made of a photochemically excited substance, and is capable of promptly moving oxygen, which is the positive electrode active material, to the positive electrode surface. By doing so, it is an object to provide a sealed photo-oxygen secondary battery capable of discharging a large current.

[0009]

A sealed type photo-oxygen secondary battery according to claim 1 comprises a positive electrode made of an oxygen catalyst, a negative electrode made of a negative electrode member made of metal, and an electrolyte in contact with the positive electrode and the negative electrode. A hermetically sealed photo-oxygen secondary having a battery case in which the positive electrode, the negative electrode, and the electrolyte are housed, and a light-receiving portion that allows light to enter the negative electrode member forming the negative electrode is provided in the battery case. A battery, wherein the electrolyte is absorbed and retained by a porous body, discharged by an oxidation reaction and a reduction reaction of oxygen of the negative electrode member, and light energy is caused to act on a discharge product generated in the negative electrode member by the discharge. By this, the discharge product is reduced and oxygen is generated to be charged.

The sealed photo-oxygen secondary battery according to claim 2 is
Oxygen is dissolved in the electrolyte, and both oxygen generated in the negative electrode during light irradiation charging and oxygen in the electrolyte act as active materials for the discharge reaction in the positive electrode.

The sealed photo-oxygen secondary battery according to claim 3 is
In the porous body, oxygen is retained in the voids of the porous body, and both oxygen generated in the negative electrode during light irradiation charging and oxygen in the porous body act as an active material of the discharge reaction in the positive electrode. It is a feature.

[0012]

In the sealed photo-oxygen secondary battery of the present invention, the discharge product formed on the surface of the negative electrode member made of metal exhibits semiconductor characteristics, and by utilizing the photoreaction of this discharge product. , The light charging reaction is realized. This eliminates the need to form the negative electrode with the semiconductor electrode. Further, since the electrolyte is absorbed and retained in the porous body, a void is formed in the electrolyte retained in the porous body, and a passage through which gas moves is formed between the negative electrode and the positive electrode. Therefore, the oxygen generated in the negative electrode during photocharging and accumulated in the battery can be quickly diffused onto the oxygen catalyst of the positive electrode during discharging. Also,
In the present invention, a gas-liquid-solid three-phase interface is easily formed by oxygen, an electrolyte, and an oxygen catalyst on the surface of the positive electrode, so that it is not necessary to subject the positive electrode to water repellent treatment. Therefore, even if the oxygen catalyst of the positive electrode is not in contact with oxygen in the outside air, it is possible to discharge with a relatively large current.

[0013]

EXAMPLES First Example First, a first example of the sealed photo-oxygen secondary battery of the present invention will be described with reference to FIGS. 1 and 2. Here, FIG. 2 shows an external view of the photo-oxygen secondary battery of this embodiment, and FIG.
3 is a cross-sectional view taken along line XX ′ in FIG. In the figure, reference numeral 21 is a positive electrode made of an oxygen catalyst, 22 is a negative electrode made of a metal negative electrode member 22a, 23 is an electrolyte that contacts the positive electrode 21 and the negative electrode 22, 24 is a porous body that absorbs and holds the electrolyte 23, and 25 is A positive electrode terminal electrically connected to the positive electrode 21 and a negative electrode 2
A negative electrode terminal electrically connected to 2 and a battery case 27.

The battery case 27 is formed in a rectangular box shape and has a light receiving portion 27a made of a light transmitting material or the like which also serves as a surface.
And a plate-shaped bottom portion 27b provided on the back surface. The battery case 27 includes a positive electrode 21 arranged on the bottom portion 27b side.
And a negative electrode 22 disposed on the light receiving portion 27a side are arranged and housed side by side, and between the bottom portion 27b and the positive electrode 21, between the positive electrode 21 and the negative electrode 22, and between the negative electrode 22 and the light receiving portion 27a.
And the porous body 24 are housed between them. The liquid electrolyte 23 is absorbed and held in the porous body 24.

The battery case 27 is not particularly limited as long as it is made of a material such as ABS resin or fluororesin that is not attacked by the electrolyte 23. However, the light receiving portion 27a of the battery case 27
Is composed of a transparent plate (transparent or colorless) such as glass, quartz glass, acrylic, or styrene that transmits at least part of visible light or part of ultraviolet light, a transparent film, or the like. Of course, the entire battery case 27 may be made of such a member as a transparent plate or a transparent film.

That is, in order for the photocharge reaction to proceed, the irradiation light needs to reach the surface of the negative electrode member 22a forming the negative electrode 22, but the irradiation light is absorbed or reflected by the battery case 27, and as a result, the negative electrode In order to prevent the light energy reaching the surface of the member 22a from being extremely reduced, it is preferable that the light receiving portion 27a be formed of a transparent plate or a transparent film.

In this sealed photo-oxygen secondary battery, in order to prevent the electrolyte 23 from decreasing, the photo-oxygen secondary battery has a sealed structure and is generated at the negative electrode 22 during light irradiation (during charging). The oxygen stored in the battery case 27 is discharged as a positive electrode active material. That is, the electrolytic solution 2
3 is sealed in the battery case 27. By thus forming the photo-oxygen secondary battery in the sealed structure, the photo-oxygen secondary battery having excellent durability can be prevented even though the oxygen is used as the positive electrode active material to prevent the electrolyte 23 from decreasing. Can be realized.

Further, in order to improve the high rate (large current) discharge characteristics by rapidly diffusing the oxygen accumulated in the battery case 27 onto the oxygen catalyst of the positive electrode 21 during discharge,
Are absorbed and retained by the porous body 24. That is, the electrolyte 2
A void 30 is formed in the anode 3, and a passage through which gas can move is formed between the anode 22 and the cathode 21. As a result, the oxygen generated in the negative electrode 22 during light charging and accumulated in the battery case 27 can be quickly diffused onto the oxygen catalyst of the positive electrode 21 during discharging. Further, by absorbing and holding the electrolyte 23 in the porous body 24, oxygen, the electrolyte 23 and the oxygen catalyst can be formed on the surface of the positive electrode 21 even if the positive electrode 21 is not composed of an oxygen catalyst which is particularly water repellent. A gas-liquid-solid three-phase interface is easily formed, and the discharge reaction can be smoothly advanced.

The positive electrode 21 is made of carbon (porous carbon) or porous nickel, and a porous oxygen catalyst (Pt-C, Pd-C, Pt-Ni, P) in which Pt or Pd is supported.
d-Ni), and further Pt, Pd, Ir, Rh, Os,
Ru, Pt-Co, Pt-Au, Pt-Sn, Pd-A
u, Ru-Ta, Pt-Pd-Au, Pt-oxide, A
u, Ag, Ag-C, Ni-P, Ag-Ni-P, Raney nickel, Ni-Mn, Ni-cobalt oxide, Cu-
Noble metals and alloys such as Ag, Cu-Au, and Raney silver, nickel boride, cobalt boride, tungsten carbide, titanium hydroxide, tungsten phosphide, niobium phosphide, transition metal carbides, spinel compounds, silver oxide, tungsten oxide. , An inorganic compound such as a perovskite type ionic crystal of a transition metal, or an organic compound such as a bacterium, a nonionic activator, a phthalocyanine, a metal phthalocyanine, activated carbon or a quinone.

The material of the negative electrode member 22a forming the negative electrode 22 is Ti, Zn, Fe, Pb, Al, Co, H.
f, V, Nb, Ni, Pd, Pt, Cu, Ag, Cd,
In, Ge, Sn, Bi, Th, Ta, Cr, Mo,
The oxides such as W, Pr, Bi, and U are composed of a metal exhibiting semiconductor characteristics, and a metal, alloy, or the like of these composite components. These metals are oxygen, nitrogen, and
A small amount of metal oxides, nitrides, carbides, hydroxides, or composite compounds of these are spontaneously generated on the surface by contact with carbon dioxide or the electrolyte 23. Will promote
It is preferable that such a compound be contained in the negative electrode member 22a.

As the electrolyte 23, a base such as potassium hydroxide, sodium hydroxide or ammonium chloride,
A liquid electrolyte such as a weak acid is used. Further, although the charging performance is lowered, a strong acid or salt such as sulfuric acid or hydrochloric acid can be used.

The porous body 24 is not particularly limited as long as it has durability against the electrolyte 23 such as glass fiber, polyamide fiber non-woven fabric, polyolefin fiber non-woven fabric, cellulose, synthetic resin or the like, that is, basic resistance or acid resistance. . However, in order to prevent the intensity of the irradiation light required for photocharging from being absorbed and attenuated by the porous body 24, at least the light receiving portion 27 of the battery case 27 in the whole porous body 24.
The portion disposed between a and the negative electrode 22 is made of a member having a property of transmitting a part of visible light or a part of ultraviolet light, such as glass fiber, or is formed in a thin film shape. preferable.

Second Embodiment Next, a second embodiment of the sealed photo-oxygen secondary battery will be described.
This will be described with reference to FIG. FIG. 3 is a diagram for explaining the second embodiment of the present invention, FIG. 3 (A) is a cross-sectional view of the sealed photo-oxygen secondary battery of the second embodiment, and FIG. 3 (B) is a diagram. Three
It is a block diagram when the electrolyte part of (A) is expanded. In the figure, reference numeral 28 is oxygen dissolved in the electrolyte 23 of the aqueous solution, and all other reference numerals are the same as those in the first embodiment. In the present embodiment, the electrolyte 23 is an aqueous electrolyte 23.
Oxygen 28 is forcibly dissolved therein by a method such as bubbling, and all other configurations are the same as in the first embodiment.

In such a sealed type photo-oxygen secondary battery, both the oxygen generated in the negative electrode 22 during light irradiation charging and the oxygen 28 dissolved in the electrolyte 23 of the aqueous solution are both charged in the positive electrode 2.
1 is used as the active material of the discharge reaction.

Third Embodiment Next, a third embodiment of the sealed photo-oxygen secondary battery will be described.
This will be described with reference to FIG. FIG. 4 (A) is a cross-sectional view showing a third embodiment of the sealed photo-oxygen secondary battery, and FIG. 4 (B) is a configuration diagram showing an enlarged part of the electrolyte of FIG. 4 (A). . In the figure, reference numeral 29 is oxygen retained in the voids 30 of the porous body 24, and all other reference numerals are the same as in the first embodiment. In the present embodiment, oxygen 29 is forcibly retained in the voids 30 of the porous body 24 by a method such as press-fitting using an oxygen cylinder in the porous body 24.
Is the same as the embodiment described above. In such a third embodiment,
Both oxygen generated in the negative electrode 22 during light irradiation charging and oxygen 29 retained in the voids 30 of the porous body 24 can act as active materials for the discharge reaction in the positive electrode 21.

The operation during charging and discharging of the sealed photo-oxygen secondary battery in the above embodiment will be briefly described below. During discharge, the metal negative electrode member 22a forming the negative electrode 22 reacts with the hydroxide ions in the electrolyte 23 on the negative electrode 22 to finally generate metal oxide and water, and the negative electrode terminal 2
Electrons are supplied to the external load through 6.

On the other hand, on the positive electrode 21, oxygen and electrolyte 23
At the three-phase interface formed by the oxygen catalyst (positive electrode) 21 and the oxygen in the electrolyte 23 and the electrons supplied (released) from the negative electrode 22 through the load react to generate hydroxide ions. In this discharge reaction, the reaction in the positive electrode 21 and the negative electrode 22 in the entire battery system is canceled out,
No reduction of the electrolyte 23 occurs. After all, what is consumed by this discharge reaction is the metal negative electrode member 22a,
A metal oxide is produced. Therefore, charging the sealed photo-oxygen secondary battery of this embodiment is nothing but reducing metal oxides.

By the way, in general, in order to realize the photocharge, in addition to the positive electrode 21 and the negative electrode 22, a photoelectrode for performing a photoreaction is required. However, the sealed optical oxygen 2 of this embodiment is
The secondary battery does not have such a photoelectrode. Nevertheless, the reason why light charging can be performed is as follows.
In this example, the metal oxide generated on the surface of the negative electrode 22 by the discharge reaction functions as a photoelectrode, and as a result, the photocharge reaction proceeds even without the photoelectrode. This charging reaction will be described in more detail.

The metal oxide as a discharge product exhibits semiconductor characteristics, and the energy band of the discharge product bends upward toward the electrolyte 23 at the contact interface between the discharge product and the electrolyte 23. At this time, when the surface of the discharge product is irradiated with light energy such as the sun or a fluorescent lamp, electrons are excited in the conduction band of the discharge product to generate holes in the valence band. This hole is filled with electrolyte 2 along the bend of the band.
It is carried to the No. 3 side and reacts with hydroxyl ions on the surface of the negative electrode member 22a to generate oxygen and water. On the other hand, the electrons excited in the conduction band move to the non-oxidized negative electrode member 22a along the bending of the band, and eventually the negative electrode member 22 made of metal.
It reaches the interface of a-metal oxide-electrolyte 23. here,
The electrons react with water in the electrolyte 23 to generate hydroxide ions, and the unreacted metal portion cannot be further reduced, so that the discharge product which is a metal oxide is reduced.
The photocharge reaction proceeds through the above process.

As described above, the first embodiment and the second embodiment
By adopting the configuration shown in the third embodiment and the third embodiment, it is possible to perform discharge using oxygen as an energy source and charge with light energy, which is not in the conventional sealed photo-oxygen secondary battery, and to use a charger. It is possible to provide a secondary battery that does not require energy and is excellent in energy saving. In particular, it is possible to provide a sealed photo-oxygen secondary battery which is excellent in durability without the possibility of the electrolyte 23 decreasing even when used for a long period under a high temperature environment.

[0031]

As described above, according to the sealed photo-oxygen secondary battery of the present invention, the following effects can be obtained. According to the sealed photo-oxygen secondary battery of claim 1, a positive electrode made of an oxygen catalyst, a negative electrode made of a metal negative electrode member, an electrolyte in contact with the positive electrode and the negative electrode, the positive electrode and the negative electrode. A battery case in which the electrolyte is housed, and the battery case is provided with a light-receiving portion for making light incident on the negative electrode member that forms the negative electrode, and discharges due to an oxidation reaction and a reduction reaction of oxygen of the negative electrode member. The discharge product generated on the negative electrode member by the discharge is subjected to light energy to reduce the discharge product and generate oxygen to be charged, so that the discharge generation generated on the surface of the negative electrode at the time of discharge. Charging by light energy is realized by utilizing the photoreactivity of an object. That is, the metal oxide as a discharge product exhibits semiconductor characteristics, and the energy band of the discharge product bends upward toward the electrolyte at the contact interface between the discharge product and the electrolyte. Light energy is applied to this discharge product to excite electrons in the conduction band of the discharge product to generate holes in the valence band. The holes are carried to the electrolyte side along the bend of the energy band and reacted with hydroxide ions on the surface of the negative electrode member to generate oxygen and water. On the other hand, the electrons excited in the conduction band are moved to the negative electrode member along the bend of the energy band, and reach the interface between the negative electrode member made of metal-metal oxide-electrolyte. Here, the electrons react with water in the electrolyte to generate hydroxide ions and reduce discharge products.

Therefore, in spite of being a photo secondary battery, a photo electrode made of a semiconductor or a chemically excited substance is not required, and a simple structure of a two-electrode system can be obtained and the battery structure can be simplified. Since the electrolyte is absorbed and retained in the porous body, voids are formed in the electrolyte retained in the porous body, and a passage through which gas moves is formed between the negative electrode and the positive electrode. Therefore, oxygen can be smoothly diffused to the surface of the positive electrode, and a photo-oxygen secondary battery having excellent discharge performance can be realized. Therefore, it is possible to provide a sealed photo-oxygen secondary battery which is excellent in discharge performance, has a simple structure and manufacture, is excellent in energy saving, and can be charged by light.

Further, according to the sealed photo-oxygen secondary battery of the second aspect, in addition to oxygen generated in the negative electrode during charging, oxygen dissolved in the electrolyte also acts as an active material of the discharge reaction. Further, it becomes possible to discharge a large current.

Further, according to the sealed photo-oxygen secondary battery of the third aspect, a large amount of oxygen can be present in the voids of the porous body as compared with the case where oxygen is dissolved only in the electrolyte. It is not limited to the amount of oxygen due to the solubility of oxygen in the gas, and a large current can be discharged.

[Brief description of drawings]

FIG. 1 is a sectional view taken along line XX ′ of FIG. 2, showing a first embodiment of the sealed photo-oxygen secondary battery of the present invention.

FIG. 2 is a perspective view of the sealed photo-oxygen secondary battery of the first embodiment shown in FIG.

FIG. 3 is a cross-sectional view showing a second embodiment of the sealed photo-oxygen secondary battery of the present invention.

FIG. 4 is a cross-sectional view showing a third embodiment of the sealed photo-oxygen secondary battery of the present invention.

FIG. 5 is a configuration diagram showing a conventional photochemical cell.

[Explanation of symbols]

 21 ... Positive electrode 22 ... Negative electrode 22a ... Negative electrode member 23 ... Electrolyte 24 ... Porous body 27 ... Battery case 27a ... Light receiving part 28/29 ... Oxygen 30 ... Void

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tsutomu Ogata 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation

Claims (3)

[Claims] 1. A positive electrode made of an oxygen catalyst, a negative electrode made of a negative electrode member made of metal, an electrolyte in contact with the positive electrode and the negative electrode, and a battery case accommodating the positive electrode, the negative electrode, and the electrolyte. A sealed-type photo-oxygen secondary battery, wherein the battery case is provided with a light-receiving part for making light incident on the negative electrode member forming the negative electrode, wherein the electrolyte is absorbed and retained by a porous body, The negative electrode member is discharged by the oxidation reaction and the reduction reaction of oxygen, and light energy is applied to the discharge product generated in the negative electrode member by the discharge to reduce the discharge product and generate oxygen to be charged. A sealed photo-oxygen secondary battery characterized by the above. 2. The electrolyte is characterized in that oxygen is dissolved, and both oxygen generated in the negative electrode during light irradiation charging and oxygen in the electrolyte act as an active material of a discharge reaction in the positive electrode. The sealed optical oxygen 2 according to claim 1.
Next battery. 3. The porous body holds oxygen in voids of the porous body, and both oxygen generated in the negative electrode during light irradiation charging and oxygen in the porous body are active materials for discharge reaction in the positive electrode. The sealed photo-oxygen secondary battery according to claim 1, wherein the sealed photo-oxygen secondary battery according to claim 1.