JP3194448B2 - Light air secondary battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a secondary battery capable of both charging and discharging, and more particularly to a light-air secondary battery which discharges using oxygen in air as an energy source and charges it with light energy. .

[0002]

2. Description of the Related Art Attempts to charge a secondary battery with light energy such as solar visible light have been made before. Such batteries include amorphous silicon solar batteries and nickel-cadmium storage batteries and lead storage batteries. 2. Description of the Related Art A solar storage battery in which a secondary battery is combined is known.

The photo secondary battery will be described with reference to FIGS. FIG. 13 is a perspective view of a conventional light secondary battery, and FIG. 14 is an equivalent circuit diagram of the light secondary battery of FIG. The optical secondary battery shown in FIG. 13 and FIG.
And a storage battery 2 for storing the power obtained by the solar cell 1
And a voltage adjusting circuit 3 for adjusting the voltage generated in the solar cell 1
And a backflow prevention diode 4 for preventing a current flowing from the solar cell 1 to the storage battery 2 from flowing back. The optical secondary battery is configured in a two-stage type (indirect type) in which the solar cell 1 generates power and the power obtained by the solar cell 1 is stored in the storage battery 2.

[0004]

However, in such a conventional photorechargeable battery, the components such as the voltage regulating circuit 3 and the backflow prevention diode 4 are indispensable. Has the disadvantage of being complex and large.

In addition, in order for the conventional light secondary battery to function properly, it is necessary to adjust the power generated by the solar cell 1 to a voltage suitable for charging the storage battery 2, and the power consumed for this adjustment is required. There is a problem that the energy loss is large. In addition, since the above-mentioned photorechargeable battery undergoes three energy conversion steps of light → electricity → electrochemistry, the number of components for this energy conversion step is increased, or energy loss due to this energy conversion step is caused. There is also a problem such as an increase in Furthermore, there are also difficulties in manufacturing the solar cell 1 such that relatively advanced manufacturing equipment such as pn junction equipment is required to manufacture the solar cell 1.

FIG. 15 is a diagram showing a conventional light storage battery. This photovoltaic cell comprises a transparent glass substrate 7, a p-type semiconductor 8, an i-type semiconductor 9, current collectors 10, 11, a cathode 12, an anode 13, a solid electrolyte 14, a passivation layer 15, a transparent A battery including the electrode 16. As in the above description, this photovoltaic battery has a complicated structure, and has disadvantages such as a problem of manufacturing a semiconductor electrode and a low energy density.

FIG. 16 shows a configuration diagram of a conventional photochemical secondary battery. In the figure, reference numeral 17 denotes a battery container, 17a.
Is a lid for sealing the battery container, 18 is a separator, 1
9 is a photoelectrode made of an n-type semiconductor, 20a is a charging electrode, and 20b is a discharging electrode. FIG. 17 shows photochemistry 2
1 shows a simple configuration and an energy level diagram of a secondary battery.

[0008] These photochemical secondary batteries make use of the electrochemical characteristics of the semiconductor-electrolyte interface, that is, convert the light energy into electricity using the bending of the energy band generated when the semiconductor electrode is brought into contact with the electrolyte. It accumulates chemically. The light conversion section of the photochemical secondary battery shown in FIG. 16 is configured by simply immersing the semiconductor electrode 19 in the electrolyte S. In this regard, the light conversion section shown in FIGS. It is superior to air secondary batteries.

However, conversion of light energy to electrochemical energy requires a photoelectrode made of a relatively expensive semiconductor material. Without this electrode, light charging cannot be performed and the cell does not function as a secondary battery. It goes without saying. Therefore, these conventional batteries have 4
It is composed of electrodes and three electrodes, and there has been a problem that it has to be a multi-electrode battery which requires one or two electrodes in addition to the positive electrode and the negative electrode. Further, as shown in FIG. 17, there is a disadvantage that the connection of the electrodes must be switched using a switch or the like in order to shift from discharging to charging (or vice versa). Further, the reaction of these batteries is based on the oxidation-reduction reaction of the electrolyte, and a large amount of electrolyte is required for increasing the capacity, and there is a disadvantage that a large energy density cannot be basically expected.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and uses oxygen in the air as an energy source to discharge and charge with light energy. It is an object of the present invention to provide an air secondary battery, and in particular, to realize a light air secondary battery having a simple configuration including a two-electrode system without necessarily requiring a photoelectrode made of a semiconductor or a photochemically excited substance.

[0011]

A light air 2 according to claim 1.
The secondary battery has a positive electrode, a negative electrode, an electrolyte in contact with the positive electrode and the negative electrode, and a battery case in which the positive electrode, the negative electrode, and the electrolyte are accommodated. A light-receiving portion for making light incident on the negative electrode member is provided,
The positive electrode is configured to have an oxygen catalyst, and is discharged by an oxidation reaction and a reduction reaction of oxygen of the metal negative electrode member forming the negative electrode, and causes light energy to act on a discharge product generated in the negative electrode member by the discharge. Thereby, the product is reduced and charged.

The light-air secondary battery according to claim 2 is the light-air secondary battery according to claim 1, wherein at least a part of the metal negative electrode member forming the negative electrode includes an oxide of the metal; Alternatively, it is characterized by being composed of a composite component metal or alloy composed of a plurality of metals.

The light-air secondary battery according to claim 3 is the light-air secondary battery according to claim 1, wherein the negative electrode member serving as a negative electrode and oxygen, nitrogen, carbon dioxide, Alternatively, it is characterized by containing compounds such as metal oxides, nitrides, carbides and hydroxides generated by contact with the electrolyte, or composite compounds thereof.

According to a fourth aspect of the present invention, there is provided a light-air secondary battery according to the first, second, or third aspect, wherein the battery case has an air hole for bringing external air into contact with the positive electrode. At least one or more are provided near the positive electrode.

A light-air secondary battery according to a fifth aspect is the light-air secondary battery according to the first, second or third aspect, wherein at least a portion near the positive electrode of the battery case is made of an oxygen-permeable member. It is a feature.

The light-air secondary battery according to claim 6 is the light-air secondary battery according to claim 4 or 5, wherein the positive electrode comprises an oxygen catalyst and an air hole or an oxygen-permeable member of a battery case. And a water repellent for preventing the electrolyte in the battery case from flowing out and permeating out of the battery through the portion.

The light-air secondary battery according to claim 7 is the light-air secondary battery according to claim 4 or 5, wherein an air hole or oxygen permeability of the battery case is provided between the positive electrode and the battery case. A water-repellent film or a water-repellent plate is provided for preventing the electrolyte from flowing out of the battery case to the outside of the battery and permeating through the portion made of the member.

The light-air secondary battery according to claim 8 is the light-air secondary battery according to claim 4 or 5, wherein oxygen is uniformly diffused between the positive electrode and the battery case on the surface of the positive electrode. It is characterized in that diffusion paper is provided.

The light-air secondary battery according to a ninth aspect is the light-air secondary battery according to the seventh aspect, wherein oxygen is applied to the surface of the positive electrode between the water-repellent film or the water-repellent plate and the battery case. In this case, a diffusion paper for diffusing the paper is provided.

[0020]

As described above, the photo-air secondary battery of the present invention has the following functions. In the light-air secondary battery according to claim 1, a metal negative electrode member serving as a negative electrode and an oxide thereof are discharged by an oxidation reaction, and light energy acts on a discharge product generated in the negative electrode member by the discharge, Since the product is configured to be reduced and charged, at the time of discharging, the metal negative electrode member or the oxide thereof forming the negative electrode is oxidized by oxygen in the air and discharged, and at the time of charging, the negative electrode is formed. Light is incident on the negative electrode member from the light receiving portion, and light energy is applied to a product generated on the negative electrode member by the oxidation, whereby the product is reduced. Therefore, such a light-air secondary battery can be charged in any of energy forms of electricity and light, and a charging reaction can proceed even during discharging.

According to a second aspect of the present invention, there is provided the photo-air secondary battery having the function of the first aspect, wherein at least a part of the metal negative electrode member forming the negative electrode comprises an oxide of the metal or a plurality of the metal negative electrodes. Since the composite member is made of a composite component metal or alloy, the negative electrode member such as an oxide of the metal exhibits semiconductor characteristics, and the negative electrode member exhibiting the semiconductor characteristics promotes the photocharge reaction.

According to a third aspect of the present invention, there is provided a photo-air secondary battery having the function of the first aspect, wherein the negative electrode member serving as a negative electrode is connected to oxygen, nitrogen, carbon dioxide, or an electrolyte in the air. Since a metal oxide, a nitride, a carbide, a compound such as a hydroxide, or a composite compound thereof is contained, a negative electrode member such as the above-described metal oxide exhibits semiconductor characteristics. The indicated negative electrode member promotes the photocharge reaction.

According to a fourth aspect of the present invention, there is provided a light-air secondary battery having the functions described in the first, second, and third aspects, and external air passes through an air hole provided in the battery case. Contact

The light-air secondary battery according to the fifth aspect has the function according to the first, second or third aspect, and air passes through the oxygen permeability of the battery case, and this air comes into contact with the positive electrode.

According to a sixth aspect of the present invention, the photo-air secondary battery has the functions of the fourth and fifth aspects, wherein oxygen is reduced by the oxygen catalyst of the positive electrode, and air holes or oxygen of the battery case are reduced by the water repellent of the positive electrode. The outflow and permeation of the electrolyte in the battery case to the outside of the battery through the portion made of the permeable member are prevented.

According to a seventh aspect of the present invention, there is provided a light-air secondary battery having the functions of the fourth and fifth aspects, wherein the water-repellent film or the water-repellent plate provided between the positive electrode and the battery case is formed of a battery case. The outflow and permeation of the electrolyte from the inside of the battery case to the outside of the battery through the hole or the portion made of the oxygen-permeable member are prevented.

[0027] In the light-air secondary battery according to the eighth aspect, while having the function of the fourth or fifth aspect, the diffusion paper provided between the positive electrode and the battery case uniformly diffuses oxygen to the positive electrode surface. Let me know.

In the light air secondary battery according to the ninth aspect, the diffusion sheet provided between the battery case and the water-repellent film or the water-repellent plate has the function of the seventh aspect, and oxygen is applied to the surface of the positive electrode. Let it spread evenly.

[0029]

1 and 2 show a first embodiment of a light-air secondary battery according to the present invention. In the drawings, reference numeral 21 denotes a positive electrode made of a conductive material or a catalyst, 22 denotes a negative electrode, 22a Is a metal negative electrode member forming a negative electrode, 23 is an electrolyte contacting the positive electrode and the negative electrode, 24 is a separator, 25 is a positive electrode terminal electrically connected to the positive electrode 21, and 26 is an electrically connected negative electrode member 22a. The negative electrode terminal, 27 is a battery case, and 28 is a water-repellent film.

The battery case 27 is formed in the shape of a rectangular box, and the light receiving portion 2 made of a light transmitting material or the like also serving as one surface.
7a, and a plate-like bottom portion 27b provided on the opposite side of the light receiving portion 27a, and a large number of air holes 29 are formed in the bottom portion 27b. The battery case 27 has a bottom 27
The positive electrode 21 disposed on the side b, the negative electrode 22 disposed on the light receiving portion 27a side, and the liquid electrolyte filled between the positive electrode 21 and the negative electrode 22 and between the light receiving portion 27a and the negative electrode 22 23 and a separator 24 provided between the positive electrode 21 and the negative electrode 22 and made of glass fiber or the like through which the electrolyte 23 can pass. Although the battery case 27 is formed in the shape of a rectangular box, the present invention is not limited to this, and may have a shape such as a column. The water-repellent film 28 is provided between the positive electrode 21 and the bottom portion 27b, has air permeability, and is configured to prevent the electrolyte 23 from flowing out.

In the photo-air secondary battery of this embodiment, the discharge reaction based on the reduction of oxygen in the air proceeds smoothly,
It is necessary to effectively form a gas-liquid-solid three-phase interface field composed of oxygen, the electrolyte 23, and the positive electrode 21 (oxygen catalyst). Therefore, the positive electrode 21 is formed of a porous oxygen catalyst for the purpose of increasing the three-phase interface field. However, when configuring a battery used for low-rate (low-current) discharge, the battery need not necessarily be porous, and a plate-shaped positive electrode 21 may be used.

The positive electrode 21 is made of carbon (porous carbon) or porous nickel, and a porous oxygen catalyst (Pt-C, Pd-C, Pt-Ni, Pt) carrying Pt or Pd on them.
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, carbides of transition metals, spinel compounds, silver oxide, tungsten oxide And inorganic compounds such as perovskite-type ionic crystals of transition metals, and organic compounds such as bacteria, nonionic activators, phthalocyanines, metal phthalocyanines, activated carbon, and quinones.

As the material of the negative electrode member 22a forming the negative electrode 22, Ti, Zn, Fe, Pb, Al, Co, H
f, V, Nb, Ni, Pd, Pt, Cu, Ag, Cd,
In, Ge, Sn, Bi, Th, Ta, Cr, Mo,
Metals whose oxides exhibit semiconductor properties, such as W, Pr, Bi, U, or at least a part of the metal is an oxide of the metal;
And it is composed of these composite component metals, alloys and the like. The negative electrode member 22a constituting the negative electrode 22 is formed by contacting oxygen, nitrogen, carbon dioxide, or a trace amount of metal oxide, nitride, carbide, hydroxide, or a composite compound thereof in the air. It is preferable that such a compound be contained in the negative electrode 22 because a product which is naturally formed on the surface but exhibits semiconductor characteristics promotes a photocharge reaction.

As the electrolyte 23 of this embodiment, a base such as potassium hydroxide, sodium hydroxide, or ammonium chloride, or a liquid electrolyte such as a weak acid is used. Further, although the charging performance is deteriorated, a strong acid or a salt such as sulfuric acid or hydrochloric acid can be used. In this embodiment, the liquid electrolyte 23 is used as described above.
Is not limited to a liquid, and any electrolyte such as a solid or a paste can be used as long as electron transfer between the positive electrode 21 and the negative electrode 22 through the electrolyte 23 is not hindered. .

The separator 24 is not particularly limited as long as it has durability against electrolytes such as glass fiber, polyamide fiber nonwoven fabric, polyolefin fiber nonwoven fabric, cellulose, synthetic resin and the like.

The battery case 27 is not particularly limited as long as it is a material such as ABS resin or fluororesin which is not affected by the electrolyte 23. However, the light receiving surface 27a located on the negative electrode side of the battery case 27 is a (colorless or colored) member that transmits at least part of visible light and part of ultraviolet light, for example,
It is composed of a transparent plate or a transparent film made of glass, quartz glass, acrylic, styrene, or the like. Of course, the entire battery case 27 may be made of a member such as a transparent plate or a transparent film. The light transmitting portion 27a is configured to transmit light as described above. When the irradiation light reaches the surface of the negative electrode member 22a forming the negative electrode 22 in order to progress the photocharge reaction, the irradiation light This is to prevent the light energy that is absorbed or reflected by the case 27 and reaches the surface of the negative electrode member 22a forming the negative electrode 22 from being extremely reduced.

On the other hand, in order for the discharge reaction based on the reduction of the oxygen in the air to proceed smoothly, the oxygen in the air must diffuse and move to the surface of the cathode 21 composed of the oxygen catalyst. For the purpose of realizing such diffusion transfer of oxygen, the battery of the present embodiment has a configuration in which at least one small-diameter air hole 29 is provided in the bottom portion 27b of the battery case 27 on the positive electrode 21 side. The air hole 29 functions as a port for taking in oxygen from the air. Therefore, as long as air can be taken in, the air hole 29 may be a large-diameter air hole or an opening.

The water-repellent film 28 is composed of the positive electrode 21 and the battery case 2
7 and the bottom 27b. This water-repellent film 2
8 shows that the electrolyte 23 passing through the hole of the positive electrode 21
Through the light-air secondary battery through the air and prevent it from flowing out (due to its water repellency), and also contributes to an increase in the three-phase interface field composed of oxygen, the electrolyte 23 and the positive electrode 21. . The water-repellent film (water-repellent plate) 28 is preferably made of, for example, a fluorine-based resin such as porous tetrafluoroethylene or a silicon-based resin.

The light-air secondary battery of this embodiment may be constructed by using a water-repellent plate instead of the water-repellent film 28. Instead of providing the water repellent film 28 and the water repellent plate, a water repellent is mixed in an oxygen catalyst to form the positive electrode 21 from the oxygen catalyst and the water repellent. A function similar to that of the water-repellent film 28 (water-repellent plate) may be provided to the positive electrode 21. In this case, the effect of increasing the three-phase interface field is further increased.

When the air hole 29 is formed small, the bottom portion 27b of the battery case 27 is formed in order to uniformly diffuse oxygen taken in from the air hole 29 over the entire surface of the positive electrode 21.
A diffusion paper 30 made of cellulose or the like may be provided between the water repellent film 28 and the positive electrode 21 containing a water repellent.

FIG. 3 is a view for explaining a second embodiment of the present invention.
The bottom 27b 'on one side is made of an oxygen-permeable member. Other configurations of the second embodiment are the same as those of the first embodiment. Bottom portion 27 of battery case 27 on positive electrode 21 side
The b 'portion is made of an oxygen-permeable member because oxygen outside the battery is diffused and moved to the surface of the positive electrode 21 made of an oxygen catalyst, and the air holes 29 are formed in the battery case 27 in the first embodiment. Is the same as

The oxygen-permeable member is preferably made of a material such as ethyl cellulose, cellulose, acetate, and butyrate, but is not limited to these as long as it is a member having oxygen permeability.

The light-air secondary battery of the first embodiment has a structure in which an air hole 29 is provided in the battery case 27 to take oxygen into the battery case 27, and the light-air air battery of the second embodiment In the secondary battery, a part of the battery case 27 is formed of an oxygen-permeable member, but the above configuration is not used, and the discharge reaction proceeds using only oxygen present in the battery case 27 and oxygen generated by charging. It is also possible to make it. Therefore, the air holes 29 are formed in the bottom 27b of the battery case 27.
It is not essential that the bottom 27b be made of an oxygen-permeable member. However, in this case, since oxygen cannot be taken in from the outside, the discharge capacity of the battery, that is, the energy density, is lower than that in the above embodiment.

The operation at the time of charging and discharging of the photo-air secondary battery in the above-described embodiment will be briefly described below. When discharging,
On the negative electrode 22, a metal negative electrode member 22 a forming the negative electrode 22
Reacts with hydroxyl ions and water molecules in the electrolyte 23 to finally generate a metal oxide and supply electrons to an external load through the negative electrode terminal 26.

On the other hand, on the positive electrode 21, oxygen and water in the electrolyte 23 and the negative electrode 22 are supplied through an external load at a three-phase interface formed by oxygen taken from the air, the electrolyte 23, and the oxygen catalyst (positive electrode) 21. The emitted electrons react with each other to generate hydroxyl ions. In this discharge reaction, the reaction in the positive electrode 21 and the negative electrode 22 is offset in the entire battery system, and thus the electrolyte 23 does not decrease at all. Oxygen as a positive electrode active material is supplied to the battery case 27.
Consumption from the air through the bottoms 27b, 27b 'of the airbag does not matter. After all, what changes by the main discharge reaction is the negative electrode member 22a forming the negative electrode 22, and a metal oxide is generated by the discharge reaction. Therefore, charging the light-air secondary battery of this embodiment is nothing but reducing the metal oxide to the original metal or a lower oxide of the metal.

In general, in order to realize light charging, a photoelectrode for performing a photoreaction is required in addition to a positive electrode and a negative electrode. However, the photo-air secondary battery of the present embodiment can perform photo-charging even though there is no photoelectrode in its configuration. This is for the following reason.

Briefly, in this embodiment, the metal oxide formed on the surface of the negative electrode member 22a forming the negative electrode 22 by the discharge reaction functions as a photoelectrode. This means that the charging reaction proceeds. That is, the metal oxide serving as the discharge product has semiconductor characteristics, and the energy band of the discharge product at the contact interface between the electrolyte 23 and the discharge product bends upward toward the electrolyte 23 side. Now, when the surface of the discharge product is irradiated with light energy such as the sun or a fluorescent lamp, it excites electrons in the conduction band and creates holes in the valence band. The holes are carried toward the electrolyte 23 along the bending of the energy band, and react with hydroxyl ions on the surface of the negative electrode member 22 a forming the negative electrode 22 to generate oxygen and water.

On the other hand, the electrons excited in the conduction band move toward the unoxidized metal side in the negative electrode 22 along the bending of the band, and eventually reach the metal-metal oxide-electrolyte interface. Reach. Then, the electrons react with water in the electrolyte 23 to generate hydroxyl ions, and the unreacted metal portion cannot be reduced any more, so that the discharge product which is a metal oxide is reduced to the metal member. Through the above process, the photocharge reaction proceeds.

As described above, by employing the configuration shown in the above embodiment, it is possible to perform discharge using oxygen in air as an energy source and charge using light energy, which are not available in the conventional light-air secondary battery. In addition, it is possible to provide a light air secondary battery which is excellent in energy saving and does not require a charger and has a high energy density. In particular, the battery can be realized with a simple configuration composed of a two-electrode system without a photoelectrode composed of a semiconductor or a photochemically excited substance. Further, it is possible to provide a battery which can be charged in any form of energy of electricity and light, and in which a photocharge reaction proceeds even during discharging.

(Experimental Example 1) Ti | KOH | P using platinum (Pt) and titanium (Ti) for the positive electrode and the negative electrode, respectively, and 1 mol / l potassium hydroxide (KOH) for the electrolyte.
Using a t (O ₂ ) -based light-air secondary battery as an example, a light-air secondary battery according to the first embodiment is prototyped, and the light-air secondary battery is capable of light charging and air discharging. Confirmed to work as

FIG. 4 shows the measurement results of the charging / discharging behavior of the above-produced Ti / O ₂ -based light air secondary battery. In the figure, the change with time of the voltage value corresponds to each measurement state of charge → open → discharge → open, and shows a state in which this series of measurements is repeated five times. The rapid rise of the battery voltage to around 1 V is a voltage recovery process due to charging. In the first and fifth cycles, electric charging was performed, and in the second to fourth cycles, light charging was performed. As a result, recovery of the battery voltage was observed by irradiating the surface of the negative electrode active material after discharging with light, and it was found that charging and discharging were possible repeatedly.

The prototype battery can be charged by either energy means of light or electricity, and no difference in discharge capacity due to the difference in charging means was observed. Further, the prototype battery exhibited excellent life characteristics without any decrease in discharge capacity even when light charge / discharge was repeated 50 times or more.

On the other hand, in order to clarify the influence of light irradiation on the battery characteristics during discharging, the discharging behavior was measured, and the results shown in FIG. 5 were obtained. In this experiment, a decrease in the battery voltage due to the discharge was hardly observed, and it was found that the photocharge reaction proceeds even during the discharge. Regarding the battery reaction, as shown in FIG. 6, the reaction potential of the positive electrode 21 was changed to oxygen / hydroxyl ion (O ₂ /
OH ⁻ ), and the oxidation-reduction potential of the positive electrode 21 was confirmed to be in progress.

It is the negative electrode potential that controls the change in the battery voltage during charging and discharging, whereby the material change of the discharge product, that is, the photoreduction reaction is proceeding on the negative electrode 22. You can see that. The battery experimentally manufactured in this experiment had a diameter of 10 mm and a thickness of 5 mm, and a xenon (Xe) light source was used for the measurement of the charge / discharge behavior. In addition, the battery which was manufactured in the experiment and used for the measurement was manufactured only for the purpose of confirming the light charging / discharging function, and the discharge capacity was greatly increased by making the anode 22 porous and optimally designed.

FIGS. 7 to 11 show changes in the oxidation state of the surface of the Ti electrode caused by the light charging and discharging of the photo-air secondary battery. 7 to 11 show the prototype Tis exemplified in the above-described Experimental Example 1.
XPS of Ti electrode used as a negative electrode member of a | KOH | Pt (O ₂ ) -based light-air secondary battery was investigated in order to examine the oxidation state of the electrode sample surface in five different states of redox state and charge / discharge state. FIG. 3 illustrates the relationship between the O1S (1S orbital of oxygen) electron binding energy (horizontal axis) and the photoelectron intensity (vertical axis) of each sample measured by (X-ray photoelectron spectroscopy) analysis. FIG. 7 shows an analysis result of a Ti electrode naturally oxidized in the atmosphere before assembling a prototype battery.
Shows that the sample of FIG. 7 was treated with 1 mol / l potassium hydroxide (KO)
H) Analysis results of Ti electrode after electrochemical reduction treatment in aqueous solution.

FIG. 9 is a graph showing the relationship between T and T after discharge in Experimental Example 1.
FIG. 10 shows the analysis result of the i-electrode, and FIG. 10 shows the analysis result of the Ti electrode after being electrically charged according to Experimental Example 1, and FIG. 11 shows the analysis result of the Ti electrode after being optically charged according to Experimental Example 1. 7 to 11, the scales on the vertical axis have different values for each sample. Also, the larger the value of the binding energy (the more the position is shifted to the left in the figure), the higher the oxidation state of the Ti metal (the larger the O / Ti atomic ratio). The results of these analyzes are summarized in FIG. FIG. 12 clearly shows a change in the oxidation state of the surface of the Ti electrode due to light charging / discharging (discharge and light irradiation) of the prototype battery.

The photoelectron peaks having intermediate binding energies shown in FIGS. 7 to 11 are due to oxides generated by reacting with the atmosphere after the battery charge / discharge experiment and before the analysis experiment. In addition, although it includes atmospheric oxidation products of Ti reduced to metal by light irradiation, FIG.

From the above measurement results, light irradiation on the higher oxide of Ti metal generated by the discharge, that is, the light reaction of the discharge product itself caused the higher oxide to become a lower oxide or metal. It can be seen that the prototype battery is lightly charged. Therefore, it can be seen that the fact that the prototype battery functions as a light-air secondary battery is supported by the level of material change in addition to the battery function.

[0059]

As described above, the light air 2 of the present invention is used.
The following effects can be obtained with the secondary battery.
According to the photo-air secondary battery according to claim 1, the positive electrode is configured to have an oxygen catalyst, and is discharged by an oxidation reaction and a reduction reaction of oxygen of a metal negative electrode member serving as a negative electrode, and the negative electrode member is discharged by the discharge. Light energy is applied to the generated discharge product to convert the product into metal, and the product is charged. During discharge, the photoreaction of the discharge product formed on the surface of the negative electrode member forming the negative electrode Charging by light energy is realized using the characteristics. Therefore, the photoelectrode composed of a semiconductor or a chemically excited substance, which is essential for the configuration of the conventional photovoltaic secondary battery, can be omitted, whereby the structure of the photoair secondary battery of the present invention is simplified, and furthermore, the manufacturing is easy. It will be easier.

Also, since an oxygen catalyst is used for the positive electrode,
Discharge using oxygen in the air as an energy source (active material) is possible. Therefore, a sufficient amount of the positive electrode active material can be easily replenished from the air, and a light-air secondary battery having a high energy density and excellent in economy and energy saving can be realized.

According to the light-air secondary battery of the second aspect,
The effect according to claim 1 can be obtained, and at least a part of the metal negative electrode member forming the negative electrode has an oxide of the metal, or a composite component metal or an alloy including a plurality of metals. Therefore, the negative electrode member exhibits semiconductor characteristics, and the negative electrode member promotes the photocharge reaction. For this reason, the light-air secondary battery can have a simple structure as compared with a case where a metal oxide or the like of the negative electrode member forms a photoelectrode and a photoelectrode is separately provided.

According to the light-air secondary battery of the third aspect,
A metal oxide, a nitride, and a carbide formed by contacting the negative electrode member with oxygen, nitrogen, carbon dioxide, or an electrolyte in the air, while being capable of achieving the effects of claim 1. , Compounds such as hydroxides,
Alternatively, since these composite compounds are included, the composite compound of the negative electrode member shows semiconductor characteristics,
Such a negative electrode member forms a photoelectrode. Therefore, the light-air secondary battery can have a simple structure as compared with a case where a photoelectrode is separately provided.

According to the light-air secondary battery of the fourth aspect,
In the battery case, at least one air hole for bringing external air into contact with the positive electrode is provided in the vicinity of the positive electrode. Therefore, external air can be sufficiently supplied to the positive electrode from the air hole, and the energy density of the light-air secondary battery can be increased.

According to the light-air secondary battery of the fifth aspect,
The effect according to claim 1, 2 or 3 can be obtained, and at least a portion near the positive electrode of the battery case is made of an oxygen-permeable member, so that external oxygen passes through the oxygen-permeable member and the positive electrode Diffusely moves to the surface. Therefore, sufficient oxygen can be supplied to the positive electrode, and the energy density of the photo-air secondary battery can be increased.

According to the light-air secondary battery of the sixth aspect,
The effect according to claim 4 or 5 can be obtained, and the positive electrode has an oxygen catalyst and an outflow and permeation of the electrolyte in the battery case to the outside of the battery through a portion formed of an air hole or an oxygen-permeable member of the battery case. And the water repellent to prevent oxygen, the oxygen is reduced by the oxygen catalyst of the positive electrode, and the water repellent of the positive electrode passes through the air hole of the battery case or the portion made of the oxygen permeable member to the outside of the battery in the electrolyte in the battery case. Outflow and permeation are prevented. Therefore, oxygen can be diffused and moved to the surface of the oxygen catalyst in a state where the electrolyte is contained in the battery case. Therefore, an interface can be formed between oxygen, the electrolyte, and the positive electrode, and the discharge reaction based on the reduction of oxygen can smoothly proceed.

According to the light-air secondary battery according to the seventh aspect,
The electrolyte according to claim 4 or 5, wherein the electrolyte flows from the inside of the battery case to the outside of the battery between the positive electrode and the battery case through an air hole or an oxygen-permeable member of the battery case. Since the structure is provided with a water-repellent film or a water-repellent plate for preventing oxygen and permeation, an interface can be formed between oxygen, the electrolyte, and the positive electrode. Therefore, the discharge reaction based on the reduction of oxygen can smoothly proceed.

According to the light-air secondary battery of the eighth aspect,
The effect according to claim 4 or 5 can be obtained, and the diffusion paper is provided between the positive electrode and the battery case to uniformly diffuse oxygen to the surface of the positive electrode. Thus, the oxygen reduction reaction can proceed smoothly.

According to the light-air secondary battery of the ninth aspect,
In addition to the effect of claim 7, the diffusion paper is provided between the water-repellent film or the water-repellent plate and the battery case to diffuse oxygen uniformly to the positive electrode surface. It can move to the surface of the positive electrode, contribute to an increase in the interface formed between oxygen, the electrolyte, and the positive electrode, and can smoothly progress the reduction reaction of oxygen.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an external view of a first embodiment of a light-air secondary battery according to the present invention.

FIG. 2 shows the X of the light-air secondary battery of the first embodiment shown in FIG.
It is sectional drawing which follows the -X 'line.

FIG. 3 is a sectional view showing a second embodiment of the photo-air secondary battery according to the present invention.

FIG. 4 shows a prototype Ti | KOH |
It is a graph which shows the measurement result of the battery voltage and charge / discharge current about a Pt (O ₂ ) -based light air secondary battery, and shows the charge / discharge behavior of this prototype battery.

FIG. 5 shows a prototype Ti | KOH | produced as an embodiment of the present invention.
It is a graph which shows the measurement result of the battery voltage and charge / discharge current about a Pt (O ₂ ) -based light air secondary battery, and shows the discharge behavior of the prototype battery under light irradiation.

FIG. 6 shows a prototype Ti | KOH |
It is a graph which shows the measurement result of the battery voltage and electrode potential regarding a Pt (O ₂ ) -based light-air secondary battery, and shows the potential of the positive electrode and the negative electrode during charging and discharging of the prototype battery.

FIGS. 7 to 11 show a prototype Ti |
Regarding the Ti electrode used as the negative electrode member of the KOH | Pt (O ₂ ) -based photo-air secondary battery, the binding energy (horizontal axis) of the 1S orbital of oxygen on the surface of this Ti electrode is
FIG. 7 shows the relationship between the photoelectron intensity (vertical axis) and the analysis result of a Ti electrode naturally oxidized in the atmosphere before assembling a prototype battery.

FIG. 8 is a graph showing T after electrochemical reduction treatment of the sample of FIG. 7 in a 1 mol / l aqueous solution of potassium hydroxide (KOH).
It is an analysis result of i electrode.

FIG. 9 is an analysis result of a Ti electrode after discharging according to Experimental Example 1;

FIG. 10 is an analysis result of a Ti electrode after being electrically charged in Experimental Example 1 described above.

FIG. 11 shows an analysis result of a Ti electrode after photocharge according to Experimental Example 1 above.

FIG. 12 is a graph clearly showing the increase / decrease of the Ti oxide and the change of the oxidation state due to the light charge / discharge (discharge and light irradiation) according to Experimental Example 1;

FIG. 13 shows an external view of a conventional light air secondary battery.

FIG. 14 shows an equivalent circuit of FIG.

FIG. 15 shows a configuration diagram of a conventional photovoltaic cell.

FIG. 16 shows a configuration diagram of a conventional photochemical secondary battery of the first example.

FIG. 17 shows a simple configuration and an energy level diagram of a second conventional photochemical secondary battery.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 21 ... Positive electrode 22 ... Negative electrode 22a ... Negative electrode member 23 ... Electrolyte 24 ... Separator 25 ... Positive electrode terminal 26 ... Negative electrode terminal 27 ... Battery case 27a ... Light-receiving part 28 ... Water-repellent film (water-repellent plate) 29 ... Air hole 30 ... Diffusion paper

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masaaki Takeuchi 1-6-1, Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (56) References JP-A-5-198319 (JP, A) JP-A Heisei JP-A-6-215806 (JP, A) JP-A-6-215807 (JP, A) JP-A-4-171681 (JP, A) JP-A-52-74831 (JP, A) JP-A-56-93270 (JP, A A) JP-A-58-127389 (JP, A) JP-A-63-19775 (JP, A) IEICE Technical Report, Vol. 91 No. 439 p. 15-20 (Heisei 4-1-24) Proceedings of the 59th Annual Meeting of the Electrochemical Society, p. 222, (Hei 4-3-19) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01M 14/00

Claims (9)

(57) [Claims] A positive electrode, a negative electrode, an electrolyte in contact with the positive electrode and the negative electrode, and a battery case in which the positive electrode, the negative electrode, and the electrolyte are accommodated.
A light-receiving portion for inputting light to the negative electrode member forming the negative electrode is provided, the positive electrode is configured to have an oxygen catalyst, and the metal negative electrode member forming the negative electrode is discharged by an oxidation reaction and an oxygen reduction reaction. A light-air secondary battery characterized in that light energy is applied to a discharge product generated in the negative electrode member by discharging, thereby reducing and charging the product. 2. The method according to claim 1, wherein at least a part of the metal negative electrode member forming the negative electrode is made of an oxide of the metal, or a composite component metal or alloy composed of a plurality of metals. Light air secondary battery. 3. A compound such as a metal oxide, a nitride, a carbide, or a hydroxide formed by contacting the negative electrode member with oxygen, nitrogen, carbon dioxide, or an electrolyte in the air. 2. The light-air secondary battery according to claim 1, further comprising a composite compound thereof. 4. The light according to claim 1, wherein the battery case is provided with at least one or more air holes for bringing external air into contact with the positive electrode near the positive electrode. Air secondary battery. 5. The photo-air secondary battery according to claim 1, wherein at least a portion near the positive electrode of the battery case is made of an oxygen-permeable member. 6. The positive electrode is composed of an oxygen catalyst and a water repellent for preventing the electrolyte in the battery case from flowing out and permeating out of the battery through an air hole or a portion formed of an oxygen-permeable member of the battery case. The light-air secondary battery according to claim 4 or 5, wherein 7. A water-repellent film for preventing electrolyte from flowing out of the battery case to the outside of the battery between the positive electrode and the battery case through an air hole or a portion made of an oxygen-permeable member of the battery case. The light-air secondary battery according to claim 4, further comprising a water-repellent plate. 8. The photo-air secondary battery according to claim 4, wherein a diffusion paper for uniformly diffusing oxygen to the surface of the positive electrode is provided between the positive electrode and the battery case. 9. The light-air secondary battery according to claim 7, wherein diffusion paper is provided between the water-repellent film or the water-repellent plate and the battery case to uniformly diffuse oxygen to the surface of the positive electrode. .