JPH09259942A - Photochemically hydrogenated secondary air battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery which can perform photocharge by high energy density, by constituting a positive electrode by a member having an oxygen catalyst and a generative electrode by a hydrogen absorbing material and an n-type semiconductor. SOLUTION: Hydrogen absorption of a hydrogen pole member 42a constituting a negative electrode 42, electron excitation action of a photopole member 42b and a potential gradient, formed by bringing the photopole member 42b into contact with an electrolyte 44, are utilized, generation of hydrogen absorption can be made by optical energy. Simultaneously, by action of an oxygen permeation suppressing film 43 provided in a position mutually separating a electrolyte contact surface between the hydrogen pole member 42a and the photopole member 42b, oxygen generated at charging time is diffused in a hydrogen pole member surface, to be prevented from returning to water by reaction with absorbed hydrogen of the negative electrode 42, an optical charge can be performed. By electrochemical reaction of oxygen by catalytic action of a positive electrode 41, a discharge with oxygen in the air serving as an active material can be attained.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an air battery and an oxygen-type battery.
Involved in hydrogen fuel cells, nickel-hydrogen cells, and photochemical cells, oxygen in the air and hydrides (occluded hydrogen) in the cells
The present invention relates to a photochemical secondary battery which is capable of discharging by reaction with and regenerating (that is, charging) by light energy, and which is excellent in energy saving and does not require a charger or replenishment of hydrogen fuel.

[0002]

2. Description of the Related Art An attempt to charge a secondary battery with light energy such as visible light from the sun has been made for a long time, and as such a battery, an amorphous silicon solar battery and a nickel-cadmium battery or a lead battery are used. A solar battery that combines a secondary battery is known. FIG. 8 is a diagram showing the appearance of a conventional photo secondary battery. FIG. 9 is a diagram showing an equivalent circuit of the battery shown in FIG. 8 and 9, reference numeral 1 is a solar cell, 2 is a secondary battery, 3 is a voltage adjusting circuit, 4 is a backflow prevention diode, 5 and 6 are positive and negative terminals, 7 is a positive and negative terminals, respectively. It is an external load connected to the terminal. These conventional photo-rechargeable batteries are two-stage type (indirect-type) photo-rechargeable batteries in which the obtained power is stored in the rechargeable battery 2 after being generated by the solar cell 1, and the voltage adjusting circuit 3 and the reverse current are used. The prevention diode 4 is necessary,
It has a drawback that the structure of the battery is complicated and large. In addition, in order for the above-mentioned conventional type photo-rechargeable battery to function properly, it is necessary to adjust the electric power generated by the solar cell 1 to a voltage suitable for charging the rechargeable battery 2, which causes a large energy loss. It has become a thing. In addition, the energy conversion step at the time of charging also has a problem of undergoing energy conversion in the form of three stages of light → electricity → electrochemistry. Furthermore, in order to manufacture the solar cell 1,
It also has manufacturing difficulties such as the need for relatively advanced manufacturing equipment such as pn junction equipment. In FIG.
P. The block diagram of a conventional photochemical secondary battery proposed by Peter et al. Is shown. In the figure, reference numeral 17 is a battery container,
Reference numeral 17a is a lid for sealing the battery container, 18 is a separator, 19 is a photoelectrode made of an n-type semiconductor, 20a is a charging electrode, and 20b is a discharging electrode. FIG. 11 is a diagram showing a simple configuration and energy levels of a conventional photochemical secondary battery proposed by Yonezawa et al. In FIG. 11, reference numeral 1
Reference numeral 1 is a positive electrode, 12 is a negative electrode, 13 is a photoelectrode made of an n-type semiconductor, 14 is a separator, 15 is a load, and 16 is a charge / discharge changeover switch. These photochemical secondary batteries utilize the electrochemical characteristics of the semiconductor-electrolyte interface,
That is, the light energy is electrochemically stored by utilizing the bending of the energy band generated when the semiconductor electrode is brought into contact with the electrolyte. The photoconversion part of the photochemical secondary battery shown in FIG. 10 is configured only by immersing the photoelectrode 19 made of an n-type semiconductor in the electrolyte S.
It is superior to the conventional photo-rechargeable batteries shown in FIGS. 8 and 9 such as solar cells which are required. However, the reaction of these batteries is
It is based on the redox reaction of the electrolyte, and all battery active materials necessary for discharging must be retained in the battery,
In order to increase the capacity, a large amount of electrolyte is required, and basically there is a drawback that a large energy density cannot be expected. In addition, there is a drawback that the connection of the electrodes has to be switched using a switch or the like in order to shift from discharging to charging (or vice versa).

On the other hand, as a battery for taking out electric energy by utilizing an electrochemical reaction of oxygen and hydrogen, there is an oxygen-hydrogen fuel cell well known as a conventional type battery. However, as a matter of course, the above fuel cell is a cell that operates and functions only while hydrogen, which is a fuel, or a raw material gas of hydrogen is supplied, and if the supply of these fuels is cut off, electrical energy can be taken out. Cannot be done and does not function as a battery. As described above, the fuel cell has a problem that the supply of fuel is essentially essential. For this issue,
As a conventional technique relating to a device for generating hydrogen by using light energy, there is a "water splitting device using light energy" in Japanese Patent Laid-Open No. 53-31576. However, in this device, only hydrogen is produced, and electrical energy cannot be taken out by the reaction. FIG. 12 shows a conventional type of “oxygen utilizing light energy-which combines these two functions.
FIG. 3 is a diagram showing a configuration of a “hydrogen fuel cell” (Japanese Patent Laid-Open No. 54-11450). In the figure, reference numeral 21 is a battery case, 22
Is an electrolytic solution, 23 is an n-type semiconductor, 24 is an oxygen electrode, 25 is a hydrogen electrode, 26 is a changeover switch for connecting the hydrogen electrode to either the n-type semiconductor or the oxygen electrode, 27 is a light receiving window, 28
Is an additional resistance, and 29 is an oxygen outlet. The oxygen-hydrogen fuel cell can obtain water output by light energy and electric output by electrochemical reaction of generated hydrogen and oxygen. In this respect, it is superior to the water splitting apparatus and the conventional fuel cell. There is. However, in the conventional battery, the changeover switch is switched between the n-type semiconductor electrode (contact point a) and the oxygen electrode (contact point b) during light irradiation (when water is decomposed) and during darkness (when electric output is taken out). I have to switch. There was a serious drawback that neither water decomposition nor discharge (obtaining electric output) was possible without such switch operation. Further, in a nickel-hydrogen battery, safety is ensured by utilizing a water-forming reaction between oxygen that is overcharged and hydrogen on a hydrogen electrode (negative electrode), and that of a wet solar cell (photochemical cell). As is clear from the operating principle, in the structure of the conventional battery, most of the oxygen generated on the surface of the n-type semiconductor electrode reacts with hydrogen on the surface of the hydrogen electrode in the water splitting reaction using light energy, and is converted into water again. Since it is not possible to prevent the progress of the returning reaction, the dark discharge had a serious drawback related to the fundamental principle that only a very small amount of residual hydrogen was available compared to the amount of photogenerated hydrogen. In particular, in order to increase the light receiving area per unit volume of the battery for the purpose of effective use of light, it is necessary to make the battery thin. In this case, the n-type semiconductor electrode and the hydrogen electrode are arranged close to each other. Therefore, the above drawbacks are fatal.

Further, FIG. 13 is a view showing a cross-sectional structural view of a "photofuel cell" (Japanese Patent Application No. 3-115077) which the present inventors have already applied for. In the figure, reference numeral 31 is a battery case, 32 and 33 are battery terminals, 34 is a first electrode, and 34 is a first electrode.
a is a water-repellent film, 35 is a second electrode, 36 is a first electrolyte, 37 is a second electrolyte, and 38 is a photocatalyst. In this photo fuel cell, during charging (when water is decomposed) and during discharging, in particular,
It is superior to the above-mentioned "oxygen-hydrogen fuel cell utilizing light energy" in that it does not require switching. However, in this photofuel cell, oxygen and hydrogen generated by photolysis of water are basically retained in the cell in the form of dissolved substances in gas or electrolyte, so that it is necessary to obtain a large discharge capacity. However, there was a drawback that the volume of the battery was inevitably increased.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is a photochemical secondary battery in which light energy is directly stored in a battery as a substance change of a negative electrode constituent material and the energy can be taken out when necessary. It is possible to discharge by reaction of oxygen in the air with hydrogen stored in the negative electrode (hydride) and to charge by light energy (hydrogenation of negative electrode constituent materials), which is excellent in energy saving without the need for a charger. It is an object of the present invention to provide a photohydrogenated air secondary battery that is a high energy density secondary battery and also has a function as an oxygen-hydrogen fuel cell that does not require refueling.

[0006]

The present invention will be described in brief. The present invention relates to a photohydrogenated air secondary battery, which comprises a positive electrode, a negative electrode, an oxygen permeation inhibiting film, and these positive and negative electrodes. It has a contacting electrolyte, a battery case containing the negative electrode, the positive electrode, and the electrolyte, and the battery case is provided with a light-receiving section for making light incident on the negative electrode member forming the negative electrode. Is composed of a member having an oxygen catalyst,
The negative electrode is composed of a hydrogen electrode member made of a material having a hydrogen storage property or a property of forming a hydride, which is electrically connected to each other, and a photoelectrode member made of an n-type semiconductor. The deterring film is made of a low oxygen permeability member, and the oxygen permeation inhibiting film separates the electrolyte contact surfaces of the hydrogen electrode member and the photoelectrode member forming the negative electrode from each other, and the photoelectrode member to the hydrogen electrode member. The oxygen migration reaction of oxygen in the hydrogen electrode member forming the negative electrode and the reduction reaction of oxygen on the oxygen catalyst forming the positive electrode, and discharging the light of the negative electrode. By the light energy irradiated on the n-type semiconductor forming the polar member,
It is characterized by being charged by advancing a hydrogenation reaction or a hydrogen storage reaction of the hydrogen electrode member of the negative electrode.

The photohydrogenated air secondary battery of the present invention has the following features and differences from conventional batteries. (1) In the photohydrogenated air secondary battery of the present invention, the positive electrode is composed of an oxygen catalyst, and the catalytic action reduces oxygen in the air to obtain an electrical output (discharge). (2) The negative electrode was composed of a hydrogen electrode member and a photoelectrode member. The hydrogen electrode member is made of a material having a hydrogen storage property or forming a hydride. The photoelectrode member is made of an n-type semiconductor, and is brought into contact with an electrolyte to form an energy band bend (potential gradient). With such a configuration, the light absorbed by the photoelectrode member is used as an energy source to cause a hydrogenation reaction (hydrogen storage reaction) of the hydrogen electrode member, and convert the light energy into a hydride (storage hydrogen). It accumulated as a material change in the negative electrode, which enabled charging. (3) The hydrogen electrode member and the photoelectrode member of the negative electrode are integrated or electrically connected. By this, 3 ~
Unlike the conventional battery having five electrodes, it is not necessary to switch the connection between the electrodes, and the switch for that is also unnecessary. Further, in the negative electrode configuration of the present invention, by bending the energy band in the photoelectrode member, that is, by forming an energy barrier, the discharge current is passed between the positive electrode and the negative electrode hydrogen electrode member through the load. The above switch can be dispensed with by adopting a configuration in which it flows in between and does not flow into the photoelectrode member. Further, with the above negative electrode configuration, the battery structure can be simplified and the energy density can be improved. (4) Further, an oxygen permeation inhibiting film is provided at a position separating the electrolyte contact surfaces of the hydrogen electrode member and the photoelectrode member that form the negative electrode from each other. In conventional batteries, oxygen generated during charging diffuses and moves to the surface of the hydrogen electrode member, reacts with the hydride (occluded hydrogen) of the negative electrode, and returns to water, making it difficult to accumulate (charge) as a hydride. . However, in the battery of the present invention, due to the action of the oxygen permeation inhibiting film, the diffusion transfer of oxygen from the photoelectrode member to the hydrogen electrode member is suppressed, and the light energy is transferred to the hydride (occluded hydrogen) in the negative electrode. It became possible to store it as a material change. (5) Further, in the battery of the present invention, the hydrogen dissociation equilibrium pressure of the hydrogen electrode member forming the negative electrode is made of a material having a pressure of 1 atm or less, so that the battery of the present invention has an open system (the battery internal pressure is large. Also in a battery (atmospheric pressure), unlike the conventional battery, it is possible to prevent a decrease in discharge capacity due to hydrogen dissociation and flowing out from the air holes. A battery having the above characteristics does not exist in conventional batteries, and is made possible for the first time by the present invention. By the technology of the present invention, discharge by reaction between oxygen in the air and hydride (occluded hydrogen) accumulated in the negative electrode and discharge by light energy (hydrogenation of negative electrode constituent material) are possible, and energy saving that does not require a charger It has become possible to provide a high-performance, high-energy-density secondary battery having excellent properties.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below. First, the embodiments of the present invention are listed below. (1) The hydrogen electrode member forming the negative electrode is characterized by being made of a material having a hydrogen dissociation equilibrium pressure of 1 atm or less and having a hydrogen storage property or a property of forming a hydride. (2) An electrolyte is not interposed between the photoelectrode member that constitutes the negative electrode and the light receiving portion of the battery case, and the light receiving surface of the photoelectrode member is not in direct contact with the electrolyte. (3) The light receiving portion of the battery case is formed of a photoelectrode member that constitutes the negative electrode. (4) The hydrogen electrode member and the photoelectrode member are in physical contact with each other to form an integral electrode to form the negative electrode. (5) The battery case is provided with at least one air hole near the positive electrode member for allowing a part of the positive electrode member to come into contact with outside air. (6) The battery case is made of an oxygen permeable member at least in the vicinity of the positive electrode member. (7) The positive electrode member is composed of an oxygen catalyst and a water repellent agent that prevents the electrolyte from flowing out and permeating to the outside of the battery through the air holes of the battery case or the portion formed by the oxygen permeable member. Is characterized by. (8) A water-repellent film or water-repellent film that prevents the electrolyte from flowing out and permeating to the outside of the battery through the air hole or the oxygen permeable member of the battery case between the positive electrode member and the battery case. It is characterized by having a plate. (9) A diffusion paper for uniformly diffusing oxygen on the surface of the positive electrode member is provided between the positive electrode member and the battery case. (10) Between the water-repellent film or water-repellent plate and the battery case,
It is characterized in that a diffusion paper for uniformly diffusing oxygen on the surface of the positive electrode member is provided. (11) The hydrogen electrode member of the negative electrode is made of a member that has already occluded hydrogen or a hydride.

[0009]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

Embodiment 1 FIGS. 1 and 2 are views for explaining a first embodiment of the present invention. FIG. 1 is an external view of the battery of the present invention, and FIG. 2 is an X- line in FIG.
It is sectional drawing which follows the X'line. In the figure, reference numeral 41 is a positive electrode made of a porous oxygen catalyst, 42a is a material having a hydrogen storage property or a property of forming a hydride, or a member having already stored hydrogen or a hydrogen electrode member made of a hydride, and 42b is an n-type. It is a photoelectrode member made of a semiconductor and constitutes the negative electrode 42 together with the hydrogen electrode member 42a. Reference numeral 43 isolates the electrolyte contact surface of the hydrogen electrode member 42a and the electrolyte contact surface of the photoelectrode member 42b, which form the negative electrode, from each other, and suppresses the movement of oxygen from the photoelectrode member surface to the hydrogen electrode member surface. An oxygen permeation inhibiting film composed of a low oxygen permeability member for preventing the contact, 44 an electrolyte contacting the positive electrode and the negative electrode, 45 a separator for preventing contact between the positive electrode and the negative electrode, 46 and 47, a positive electrode terminal and a negative electrode terminal, 48 Is a battery case (container) for housing these battery components, 49 is a water-repellent film, and 50 is a battery case 48.
And 51 are connecting conductors for connecting the hydrogen electrode member 42a and the photoelectrode member 42b. The battery case 48 is
The light receiving portion 48a is formed in a rectangular box shape and is made of a light transmitting material or the like that also serves as one surface, and a plate-like bottom portion 48b provided on the opposite side of the light receiving portion 48a.
A large number of air holes 50 are formed in this. The air holes 50 are also provided in part in the battery case portion near the photoelectrode member 42b of the negative electrode to release oxygen generated from the surface of the photoelectrode member during charging to the outside. The battery case 48 has a bottom 48
The liquid electrolyte 44 filled between the positive electrode 41 arranged on the b side and the negative electrode 42 arranged on the light receiving part 48a side, and between the light receiving part 48a and the negative electrode 42, and the positive electrode 41 and the negative electrode. A separator 45, which is provided between the hydrogen electrode member 42a and the n-type semiconductor member 42b, is provided between the hydrogen electrode member 42a and the n-type semiconductor member 42b. Has been done. Although the battery case 48 is formed in the shape of a rectangular box, the present invention is not limited to this and may have a cylindrical shape or the like. The water-repellent film 49 is disposed between the positive electrode 41 and the air hole 50, has air permeability, and is configured to prevent the electrolyte 44 from flowing out. In the photohydrogenated air secondary battery of this example, in order to smoothly proceed the discharge reaction based on the reduction of oxygen in the air, oxygen, the electrolyte, and the positive electrode (oxygen catalyst) were used.
It is necessary to effectively form a field at the gas-liquid-solid three-phase interface composed of and. Therefore, for the purpose of increasing the above three-phase interface field, the positive electrode was composed of a porous oxygen catalyst. However, when a battery used for low rate (low current) discharge is constructed, it need not necessarily be porous, and a plate-shaped positive electrode may be used.

In the above embodiment, the positive electrode 41 is made of carbon (porous carbon) or porous nickel having an oxygen catalytic action,
And a porous oxygen catalyst (P, P
t-C, Pd-C, Pt-Ni, Pd-Ni), and
Pt, Pd, Ir, Rh, Os, Ru, Pt-Co, P
t-Au, Pt-Sn, Pd-Au, Ru-Ta, Pt
-Pd-Au, Pt-oxide, Au, Ag, Ag-C,
Ni-P, Ag-Ni-P, Raney nickel, Ni-M
Noble metals and alloys such as n, Ni-cobalt oxide, Cu-Ag, Cu-Au, and Raney silver, nickel boride, cobalt boride, tungsten carbide, titanium hydroxide, tungsten phosphide, niobium phosphide, and transition metal carbides. , Spinel compounds, silver oxide, tungsten oxide, inorganic compounds such as perovskite ionic crystals of transition metals, and organic compounds such as bacteria, nonionic activators, phthalocyanines, metal phthalocyanines, activated carbon, and quinones. Is preferred.

Further, the hydrogen electrode material 42 constituting the negative electrode 42
a is a La-Ni system alloy, a La-Nd-Ni system alloy, L
a-Gd-Ni-based alloy, La-Y-Ni-based alloy, La-
Co-Ni type alloy, La-Ce-Ni type alloy, La-N
i-Ag type alloy, La-Ni-Fe type alloy, La-Ni
-Cr alloy, La-Ni-Pd alloy, La-Ni-
Cu-based alloy, La-Ni-Al-based alloy, La-Ni-M
n-based alloy, La-Ni-In-based alloy, La-Ni-Sn
Type alloy, La-Ni-Ga type alloy, La-Ni-Si type alloy, La-Ni-Ge type alloy, La-Ni-Al-C
o-based alloy, La-Ni-Al-Mn-based alloy, La-Ni
-Al-Cr based alloy, La-Ni-Al-Cu based alloy,
La-Ni-Al-Si based alloy, La-Ni-Al-T
i-based alloy, La-Ni-Al-Zr-based alloy, La-Ni
-Mn-Zr-based alloy, La-Ni-Mn-Ti-based alloy,
La-Ni-Mn-V based alloy, La-Ni-Cr-Mn
Type alloy, La-Ni-Cr-Zr type alloy, La-Ni-
Fe-Zr-based alloys, La-Ni-Cu-Zr-based alloys, alloys in which the La element in the above alloys is replaced by misch metal, Ti-Zr-Mn-Mo-based alloys and Zr
Ti, F such as -Fe-Mn-based alloy and Mg-Ni-based alloy
e, Mn, Al, Ce, Ca, Mg, Zr, Nb, V,
Hydrogen storage alloys such as alloys composed of two or more combinations of Co, Ni and Cr elements, and further Ti, V, Zr, La and P
It is preferable to be composed of a metal (having a hydrogen storage property) that forms a hydride such as d or Pt, or a hydride of the above alloy or metal (a substance that stores hydrogen). In particular, in a semi-open battery such as the battery of this embodiment, it is difficult to make the internal pressure of the battery equal to or higher than the atmospheric pressure because the air holes 50 are provided for utilizing oxygen in the outside air for the discharge reaction. Is. Therefore, in order to prevent the reduction of the discharge capacity due to the dissociation of the hydride (occluded hydrogen) generated in the negative electrode by charging,
It is desirable that the hydrogen electrode member is made of a material having a dissociation equilibrium pressure of hydrogen of 1 atm or less.

In the photoelectrode member 42b, the valence band level at the interface with the electrolyte 44 is nobler than the oxygen generation potential, and the conduction band level is the hydrogen electrode member 42a.
S at a base potential lower than that of the hydrogenation reaction that proceeds above
n such as rTiO ₃ , TiO ₂ , CdS, SiC, GaP
It is preferably composed of a type semiconductor. In addition to the compound semiconductor, the present light pole member may be a single element semiconductor, a condensed polycyclic aromatic compound, an organic semiconductor, an n-type semiconductor, and
Any combination of the electrolyte 44 and the hydrogen electrode member 42a may be used as long as it satisfies the level (potential), and the kind of material is not particularly limited.

The electrolyte 44 contains potassium hydroxide,
It is composed of a base such as sodium hydroxide or ammonium chloride or an aqueous electrolyte such as a weak acid. Further, although the charging performance is lowered, a strong acid or salt such as sulfuric acid or hydrochloric acid can be used. In this example, the liquid electrolyte is used,
The electrolyte 44 is not limited to a liquid and may be a paste or the like.

The oxygen permeation inhibiting film 43 is made of glass fiber, polyamide fiber nonwoven fabric, polyolefin fiber nonwoven fabric, polypropylene, polyethylene or Nafion.
Although it is composed of a membrane, an ion exchange membrane, a cellulose membrane, a synthetic resin, or the like, it is not limited to the above materials as long as it is a membrane that prevents diffusion and movement of oxygen and allows an electrolyte to permeate.

The separator 45 is made of glass fiber, polyamide fiber nonwoven fabric, polyolefin fiber nonwoven fabric,
Although it is composed of cellulose, synthetic resin, or the like, it is not particularly limited as long as it has durability against an electrolyte, and the oxygen permeation inhibiting film 43 may be used.

The battery case (container) 48 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 44. However, the light receiving portion 48a of the battery case 48 is composed of a transparent plate or a transparent film such as glass, quartz glass, acrylic, or styrene that transmits at least part of visible light or part of ultraviolet light (colorless or colored). To do. Of course, the entire battery case 48 may be composed of these members. As described above, the light receiving portion 48a is configured to transmit at least a part of visible light or a part of ultraviolet light, so that the irradiation light reaches the surface of the photoelectrode member 42b in order to promote the photocharge reaction. This is to prevent the irradiation light from being absorbed or reflected by the battery case 48 and lowering the light energy reaching the surface of the photoelectrode member.

On the other hand, in order for the discharge reaction based on the reduction of oxygen in the air to proceed smoothly, the oxygen must diffuse and move to the surface of the positive electrode comprising the oxygen catalyst. For the purpose of realizing such diffusion and transfer of oxygen, the battery of the present embodiment has a bottom portion 48b on the positive electrode 41 side of the battery case 48.
In this configuration, the air hole 50 including at least one small hole is provided. The air hole 50 functions as an oxygen intake port from the air, and instead of the small hole, a large diameter air hole or an opening may be used.

The water-repellent film (water-repellent plate) 49 is provided between the positive electrode 41 and the air hole 50 of the battery case 48.
This water-repellent film 49 is used for the electrolyte 44 that has passed through the holes in the positive electrode.
Has a function of preventing permeation and outflow to the outside of the battery through the air holes 50 (due to its water repellency), and also contributes to increase of the gas-liquid solid three-phase interface field. The water-repellent film (water-repellent plate) 49 is preferably made of a fluorine-based resin such as porous tetrafluoroethylene or a silicon-based resin.
It is needless to say that the water-repellent film 49 can use the water-repellent plate instead of the water-repellent film to form the battery of the present invention. Also, instead of installing a water-repellent film or water-repellent plate,
The present invention can also be achieved by mixing a water repellent agent in the positive electrode to form a positive electrode from an oxygen catalyst and a water repellent agent, and by giving the positive electrode the function of the water repellent film (water repellent plate). A battery can be constructed. In this case, the effect of increasing the three-phase interface field is further increased. When the air holes are formed of small holes, the bottom 48b of the battery case is formed in order to uniformly diffuse the oxygen taken in from the air holes 50 over the entire positive electrode surface.
A diffusion paper 50 made of cellulose or the like may be provided between the water-repellent film 49 or the positive electrode 41 containing the water-repellent agent.

Second Embodiment FIG. 3 is a diagram for explaining a second embodiment of the present invention.
The bottom 48b of the battery case 48 on the positive electrode side and a part of the negative electrode in the vicinity of the photoelectrode member are constituted by the oxygen permeable member 52. The other structure of this embodiment is similar to that of the first embodiment. The bottom portion 48b of the battery case is made of an oxygen permeable member because the oxygen outside the battery is formed by the positive electrode 4 made of an oxygen catalyst.
1 is to diffuse and move to the surface, and part of the vicinity of the photoelectrode member is formed of the oxygen permeable member 52 in order to discharge oxygen generated during charging to the outside. This has the same effect as forming the air holes 50 in the battery case in the example.

The oxygen permeable member 52 is preferably composed of an oxygen permeable member such as ethyl cellulose, cellulose, acetate and butyrate, but any member having an oxygen permeable property may be used and is not limited thereto. Not a thing.

Of course, in the battery of the present invention, it is possible to proceed the discharge reaction by utilizing only the oxygen existing in the battery case and the oxygen generated by charging, and it is not always necessary to form an air hole at 48b at the bottom of the battery case. It is not necessary to provide or configure it with an oxygen permeable member. However, in this case, since it is impossible to take in oxygen from the outside, the discharge capacity of the battery, that is, the energy density is lower than that in the first and second embodiments.

Embodiment 3 FIG. 4 is a diagram for explaining the third embodiment of the present invention.
The electrolyte 44 is not interposed between the light receiving surface of the negative electrode light electrode member 42b and the light receiving portion 48a of the battery case, and the light receiving surface of the light electrode member does not come into direct contact with the electrolyte. Other configurations are the same as those of the first embodiment. It is needless to say that a battery having the above structure and having the other structure as the embodiment of the present invention can form a battery similar to that of the second embodiment.

Fourth Embodiment FIG. 5 is a diagram for explaining a fourth embodiment of the present invention,
The light receiving portion 48a of the battery case is the negative electrode photoelectrode member 42b.
And the photoelectrode member also serves as a part of the battery case, and the other structure is the same as that of the first embodiment. Also,
It goes without saying that, as an embodiment of the present invention, it is possible to construct a battery having the above-mentioned structure and having the other structure similar to that of the second embodiment. In the third and fourth embodiments, the irradiation light reaches the photoelectrode without passing through the electrolyte, so that the light charging efficiency is higher than that in the first and second embodiments. Can be raised. It is also possible to use a light absorbing member as the electrolyte.

Embodiment 5 FIG. 6 is a diagram for explaining the fifth embodiment of the present invention.
In the battery of the present embodiment, the hydrogen electrode member 42a and the photoelectrode member 42b forming the negative electrode 42 are in physical contact with each other to form an integrated electrode (composite electrode) to form the negative electrode 42. . This eliminates the need for the connecting conductor 51 between the hydrogen electrode member 42a and the photoelectrode member 42b, which is required in the above embodiment, and improves the reliability of the battery.
Since the connection area between the hydrogen electrode member 42a and the photoelectrode member 42b is significantly increased and the resistance loss between both members is reduced, the charging efficiency by light is improved as compared with the first to fourth embodiments. It goes without saying that the batteries of the examples of the present invention also have the above-described structure, and can have the other structures in the same manner as the batteries of the second example.

The operation of charging and discharging the photohydrogenated air secondary battery in the above embodiment of the present invention will be briefly described below.
FIG. 7 shows an outline of the charge / discharge reaction of the battery of the present invention and an example of the reaction formula. That is, at the time of discharge, hydrogen in the hydrogenated negative electrode member 42 a of the hydrogenated electrode and hydroxide ion (O 2 in the electrolyte 44).
H ⁻ ) reacts with hydrogen to escape from the alloy or metal that is the hydrogen electrode member to generate water, and also supplies electrons (e ⁻ ) to the load through the negative electrode terminal 47. On the other hand, on the positive electrode 41, at the three-phase interface formed by oxygen taken from the air, the electrolyte 44 and the oxygen catalyst (positive electrode) 41, oxygen and water in the electrolyte and the negative electrode are supplied (released) through a load. React with the generated electrons to generate hydroxide ions. In this discharge reaction, oxygen, which is the positive electrode active material, is taken in from the air, so that its consumption is not a problem.
After all, in the present discharge reaction, an electric output can be obtained by a reaction of producing water from oxygen in the air and hydrogen in the hydride in the battery.

Next, the operation during charging / discharging will be briefly described.
At the contact interface between the photoelectrode member 42b made of an n-type semiconductor and the electrolyte 44, the energy band in the photoelectrode member bends upward toward the electrolyte. Now, when the light energy of the sun or a fluorescent lamp is applied to the surface of this photoelectrode,
It excites electrons in the conduction band and creates holes (h ⁺ ) in the valence band. The holes are carried to the electrolyte side along the bend of the band, and react with hydroxyl ions on the surface of the negative electrode photoelectrode member 42b to generate oxygen and water. On the other hand, the electrons excited in the conduction band move to the hydrogen electrode member 42a via the connection conductor 51 (directly in the fifth embodiment) along the bend of the band, and eventually reach the negative electrode surface in contact with the electrolyte. . Then, by reacting with water in the electrolyte to generate hydroxide ions, the alloy or metal (M) that is a hydrogen electrode member is hydrogenated to form a hydride (hydrogen storage material) MH _n , thereby causing discharge. Return to the previous state. Through the above process, the photocharge reaction proceeds,
It can be discharged again. After all, in the charge / discharge reaction of the battery of this example, hydrogen is exchanged (moved in and out) between the hydrogen electrode member 42a of the negative electrode and the electrolyte 44 like a piston. The electrons generated in the hydrogen electrode member at the time of discharge are exclusively supplied to the load (finally the positive electrode) without moving to the photoelectrode member electrically connected to the hydrogen electrode. This utilizes the fact that electrons cannot move toward the electrolyte interface due to the bending of the energy band in the photoelectrode member. In addition, in the battery of this embodiment, light charging (irradiation)
Oxygen generated on the photoelectrode member surface 42b sometimes diffuses and moves to the hydrogen electrode member surface 42a, reacts with the hydride (MH _n ) generated by the photocharge reaction and returns to water, and accumulates as hydride ( The phenomenon that it cannot be charged does not occur. This is due to the action of the oxygen permeation inhibiting film 43 which is provided so as to separate the electrolyte contact surfaces of the hydrogen electrode member and the photoelectrode member from each other. It became possible to suppress the diffusion transfer of oxygen to the hydrogen electrode member, and to store the light energy as a material change to the hydride in the negative electrode. Furthermore,
In this embodiment, since the hydrogen dissociation equilibrium pressure of the hydrogen electrode member constituting the negative electrode is set to be low, hydrogen is dissociated even in the open system battery as in this embodiment, and the air hole 5
It is possible to prevent the discharge capacity from decreasing due to the outflow from 0 to the outside.

Example 6 Mesh oxygen-like platinum (Pt) was used for the positive electrode oxygen catalyst, and LaNi _3.76 Al having a shape of 15 mm × 15 mm was used for the negative electrode hydrogen electrode member.
_1.24 Similarly, SrTiO ₃ was used for the negative electrode photoelectrode member, potassium hydroxide (KOH) aqueous solution for the electrolyte, microporous glass fiber and Nafion film for the oxygen permeation inhibiting film, and quartz glass for the light receiving part. SrTiO 3 according to the first embodiment
_{A 3-} MH _n | KOH | O ₂ (Pt) -based photohydrogenated air secondary battery was prepared and a charge / discharge test was conducted. A 500 W Xe (xenon) lamp was used as a light source for light irradiation. As a result, the battery voltage is about 1V and the discharge capacity is 100mAh.
In addition to the above, the hydrogenation charge reaction proceeded by light irradiation, and repeated discharge was possible. These results show that the measured equilibrium potential of LaNi _3.76 Al _1.24 used for the hydrogen electrode member of the above-mentioned negative electrode is about −0.8 _V (Hg / HgO electrode standard), which is considerably noble as compared to LaNi _{5 and the} like. Since the hydrogenation reaction has a property of advancing even at a potential, the battery of this example has a configuration in which the photohydrogenation charging reaction easily proceeds, and the hydrogen dissociation equilibrium pressure of the alloy is about 1.5 ×.
Due to the extremely low pressure of 10 ⁻³ atm, dissociation of hydrogen was suppressed, and further, due to the action of the oxygen permeation inhibiting film, diffusion of oxygen generated by light irradiation was suppressed,
This is due to the action and effect of the present invention such that the recombination reaction with the hydride could be prevented. As described above, by adopting the configurations shown in the first, second, third, fourth, fifth, and sixth embodiments, oxygen in air and negative electrode Discharge by reaction with hydrogen accumulated in and hydrogen charge by light energy are possible.
It is possible to provide a high energy density secondary battery excellent in energy saving that does not require a charger.

[0029]

As described above, in the photohydrogenated secondary battery of the present invention, the hydrogen storage (hydride formation) action of the hydrogen electrode member constituting the negative electrode, and the electron excitation action and the photoexcitation action of the photoelectrode member. By utilizing the potential gradient (bend of energy band) formed by contacting the electrode member with the electrolyte, it is possible to cause the hydrogenation (hydrogen storage) reaction by light energy, and at the same time, the hydrogen electrode member and the light Oxygen generated at the time of charging diffuses and moves to the surface of the hydrogen electrode member due to the action of the oxygen permeation inhibiting film provided at the position where the electrolyte contact surface with the electrode member is isolated from each other, and reacts with the hydride of the negative electrode (storage hydrogen). By preventing it from returning to the water, it enables light charging. In addition, the electrochemical reaction of oxygen by the catalytic action of the positive electrode enables discharge using oxygen in the air as an energy source (active material). in this way,
INDUSTRIAL APPLICABILITY According to the present invention, it is possible to discharge by the reaction of oxygen in the air, which exists substantially infinitely, with hydride (storage hydrogen) in the battery, and also to charge by the light energy, which exists infinitely in the surroundings. It is possible to realize a photochemical secondary battery with a high energy density. Therefore, the present invention substantially functions as an oxygen-hydrogen fuel cell that does not require refueling, has an excellent energy saving property, and can provide a secondary battery capable of being photocharged at a high energy density, which is a great effect. There is.

[Brief description of drawings]

FIG. 1 is a view showing an appearance of a photohydrogenated air secondary battery according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a cross-sectional view taken along line XX ′ of FIG.

FIG. 3 is a diagram illustrating a second embodiment of the present invention.

FIG. 4 is a diagram illustrating a third embodiment of the present invention.

FIG. 5 is a diagram illustrating a fourth embodiment of the present invention.

FIG. 6 is a diagram illustrating a fifth embodiment of the present invention.

FIG. 7 is a diagram for explaining a charge / discharge reaction of the battery of the present invention, showing an outline of the reaction and an example of a reaction formula.

FIG. 8 is a view showing an appearance of a conventional photo secondary battery.

FIG. 9 is a diagram showing an equivalent circuit of FIG.

FIG. 10 is a diagram showing a structure of a conventional photochemical secondary battery.

FIG. 11 is a diagram showing a simple configuration and energy levels of a conventional photochemical secondary battery proposed by Yonezawa et al.

FIG. 12 is a diagram showing a configuration of an “oxygen-hydrogen fuel cell utilizing light energy” described in JP-A No. 54-11450.

FIG. 13 is a diagram showing a cross-sectional configuration diagram of a “photofuel cell” described in the drawing of Japanese Patent Application No. 3-115077.

[Explanation of symbols]

1: Solar battery, 2: Secondary battery, 3: Voltage adjustment circuit, 4:
Backflow prevention diode, 5: positive electrode terminal, 6: negative electrode terminal,
7: external load connected to the positive electrode terminal and the negative electrode terminal, 11:
Positive electrode, 12: negative electrode, 13: photoelectrode made of n-type semiconductor,
14: separator, 15: load, 16: charge / discharge changeover switch, 17: battery container, 17a: lid for sealing the battery container, 18: separator, 19: photoelectrode made of n-type semiconductor, 20a: for charging Electrode, 20b: Electrode for discharge, 21: Battery case, 22: Electrolyte, 23: n-type semiconductor, 24: Oxygen electrode, 25: Hydrogen electrode, 26: Hydrogen electrode is either an n-type semiconductor or an oxygen electrode Switch for connecting to, 27: light receiving window, 28: additional resistance, 29: oxygen outlet, 31: battery case, 32, 33: battery terminal, 3
4: first electrode, 34a: water-repellent film, 35: second electrode, 36: first electrolyte, 37: second electrolyte, 38:
Photocatalyst, 41: Positive electrode made of porous oxygen catalyst, 42: Negative electrode, 42a: Hydrogen electrode member, 42b: Photoelectrode member, 43: Electrolyte contact surface of hydrogen electrode member 42a constituting the above-mentioned negative electrode and electrolyte of photoelectrode member 42b An oxygen permeation inhibiting film made of a low oxygen permeability member for isolating the contact surface from each other and suppressing the movement of oxygen from the surface of the photoelectrode member to the surface of the hydrogen electrode member, 44: contacting with the positive electrode and the negative electrode Electrolyte, 4
5: Separator for preventing contact between positive electrode and negative electrode, 46: positive electrode terminal, 47: negative electrode terminal, 48: battery case (container) containing these battery constituent members, 49: water-repellent film, 50:
Air holes provided in the battery case 48, connection conductors 51: 42a and the photoelectrode member 42b, 52: oxygen permeable member

Claims (12)

[Claims] 1. A positive electrode, a negative electrode, an oxygen permeation inhibiting film, an electrolyte in contact with the positive electrode and the negative electrode, a battery case accommodating the negative electrode, the positive electrode and the electrolyte,
The battery case is provided with a light-receiving portion for injecting light into the negative electrode member forming the negative electrode, the positive electrode is formed of a member having an oxygen catalyst, and the negative electrodes are electrically connected to each other. And a hydrogen electrode member made of a material having a property of forming a hydride and a photoelectrode member made of an n-type semiconductor, wherein the oxygen permeation inhibiting film is made of a low oxygen permeability member, and the oxygen The permeation-inhibiting film separates the electrolyte contact surfaces of the hydrogen electrode member and the photoelectrode member forming the negative electrode from each other to suppress the diffusion and movement of oxygen from the photoelectrode member to the hydrogen electrode member, and forms the negative electrode. By the oxidation reaction of hydrogen in the hydrogen electrode member and the reduction reaction of oxygen on the oxygen catalyst constituting the positive electrode, discharge is caused, and by the light energy irradiated on the n-type semiconductor forming the negative electrode photoelectrode member, ,Up Light hydrogenation air secondary battery, characterized in that it is charged by advancing the hydrogenation reaction, or hydrogen absorbing reaction of the negative electrode of the hydrogen electrode member. 2. The hydrogen electrode member forming the negative electrode is made of a material having a hydrogen dissociation equilibrium pressure of 1 atm or less, a hydrogen storage property, or a property of forming a hydride. The photohydrogenated air secondary battery described. 3. The electrolyte is not interposed between the photoelectrode member constituting the negative electrode and the light receiving portion of the battery case, and the light receiving surface of the photoelectrode member does not come into direct contact with the electrolyte. Alternatively, the photohydrogenated air secondary battery according to item 2. 4. The light receiving portion of the battery case is formed of a photoelectrode member that constitutes the negative electrode.
Alternatively, the photohydrogenated air secondary battery according to item 2. 5. The photohydrogen according to claim 1, wherein the hydrogen electrode member and the photoelectrode member are in physical contact with each other to form an integral electrode to constitute the negative electrode. Air secondary battery. 6. The battery case is provided with at least one air hole near the positive electrode member for allowing a part of the positive electrode member and external air to come into contact with each other. 6. The photohydrogenated air secondary battery according to any one of items 1 to 5. 7. The photohydrogenated air secondary battery according to claim 1, wherein the battery case is made of an oxygen permeable member at least in the vicinity of the positive electrode member. 8. The positive electrode member is composed of an oxygen catalyst and a water repellent which prevents the electrolyte from flowing out and permeating to the outside of the battery through an air hole of the battery case or a portion formed by an oxygen permeable member. 1 to 7 characterized in that
The photohydrogenated air secondary battery according to any one of 1. 9. A water-repellent film for preventing the electrolyte from flowing out and permeating to the outside of the battery through the air hole of the battery case or a portion formed of an oxygen permeable member between the positive electrode member and the battery case. The photohydrogenated air secondary battery according to claim 1, further comprising a water-repellent plate. 10. Between the positive electrode member and the battery case,
The photohydrogenation air secondary battery according to claim 9, further comprising a diffusion paper for uniformly diffusing oxygen on the surface of the positive electrode member. 11. The diffusion paper for uniformly diffusing oxygen on the surface of the positive electrode member is provided between the water-repellent film or water-repellent plate and the battery case. The photohydrogenated air secondary battery described. 12. The photohydrogenated air secondary battery according to claim 1, wherein the hydrogen electrode member of the negative electrode is made of a member that has already occluded hydrogen or a hydride. .