JP3025798B2 - Photochemical secondary battery and method of manufacturing photochemical secondary battery - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a chargeable / dischargeable secondary battery, and more particularly to a secondary battery which can be charged with light energy.

[Conventional technology and its problems]

Attempts to charge a secondary battery with light energy such as solar visible light have been made for a long time.
2. Description of the Related Art A solar storage battery in which an amorphous silicon solar cell is combined with a secondary battery such as a nickel-cadmium storage battery or a lead storage battery is known. FIG. 9 shows an external view of a conventional photorechargeable battery, and FIG. 10 shows an equivalent circuit diagram of the battery shown in FIG. This conventional light secondary battery uses the power obtained by the solar cell
Is a two-stage type (indirect type) light secondary battery that stores power in a solar cell 14 and a storage battery 15.
However, there is a disadvantage that the structure of the battery is complicated and large, for example, it is necessary to provide the battery between them. Further, in order for such a battery to function properly, the power generated by the solar cell 1 needs to be adjusted to a voltage suitable for charging the storage battery 15 by the voltage adjustment circuit 16, and the energy loss for that purpose is also reduced. It has become big. In addition, the energy conversion step also has a problem that energy conversion is performed in three stages of light → electricity → electrochemistry. Further, in order to manufacture the solar cell 1, relatively high-level manufacturing equipment such as a pn junction equipment is required, and there is also difficulty in manufacturing.

On the other hand, many studies have already been made on a photochemical cell that converts light energy into electric energy by utilizing the bending of an energy band generated when a semiconductor electrode is brought into contact with an electrolyte. However, these are generally called wet solar cells, and as shown in FIG. 11, the electrochemical oxide generated on the surface of the semiconductor photoelectrode 1 is immediately reduced on the surface of the counter electrode 18. , The electrolyte 14 is always kept in the initial state, and naturally
There is no power storage function as a secondary battery. Also, as shown in FIG. 12, an attempt has been made to produce oxygen and hydrogen from the aqueous electrolyte 4 by light energy by applying the same principle as the battery of FIG. Although the oxygen and hydrogen produced here can be used as an energy source of a fuel cell, the present cell does not necessarily have a function as a secondary cell.

An object of the present invention is to provide a photochemical secondary battery capable of directly converting and storing light energy into electrochemical energy and extracting the energy when needed, that is, a light-chargeable secondary battery having a simple structure and manufacturing. To provide.

[Means for solving the problem]

The photochemical secondary battery of the present invention has a photoelectrode made of an n-type semiconductor at least one surface of which is immersed in an electrolyte, a negative electrode immersed in the electrolyte, and electrically connected to the photoelectrode. Means for solving the problem include a positive electrode which is immersed in the electrolyte via a negative electrode and a separator, and which is electrically insulated from the light electrode.

 Hereinafter, the present invention will be described in detail.

The present invention provides a battery capable of causing an electrochemical substance change directly by light energy, storing (charging) the substance, and discharging when necessary, by utilizing the electrochemical characteristics of the semiconductor and the electrical interface. That is the biggest feature.
To achieve this, the present invention differs from the prior art in the following points. That is, only by immersing the light electrode (semiconductor electrode) in the electrolyte, the same energy band bending as in the pn junction of a solar cell or the like was produced. In addition, the load and the positive electrode are electrically connected directly to the light pole, and the positive electrode or the negative electrode, which is one of the poles of the secondary battery, is arranged near the light pole, whereby the light pole is electrically connected to the light pole. The charging reaction by the light between the positive electrode or the negative electrode and the discharging reaction between the positive electrode and the negative electrode are realized in one battery. In order to realize a secondary battery with a relatively high voltage, the negative electrode of the p-type light pole, the n-type light pole and the positive electrode are electrically connected, and the p-type light pole and the positive electrode, and n
The photoelectrode and the negative electrode were arranged in the vicinity, and all these electrodes were brought into contact with the same electrolyte to constitute a photochemical secondary battery. In order to improve the conversion (charge) efficiency by light, a ferroelectric semiconductor is used as a light pole, and an electric field is applied in advance vertically to the surface of the light pole, and then the electric field is removed to form a battery. As a result, the polarization plane structure is maintained even after removing the external electric field,
The efficiency of separation of holes and excited electrons in the light pole by light can be improved, and as a result, the charging efficiency of the battery of the present invention can be improved. The photoelectrode is composed of a condensed polycyclic aromatic compound that is an organic semiconductor that is relatively easy to manufacture.

〔Example〕

1 and 2 are views for explaining a first embodiment of the present invention, wherein reference numeral 1 denotes a light pole made of an n-type semiconductor. Symbols 2 and 3 are a positive electrode and a negative electrode, respectively, symbol 4 is an electrolyte, symbol 5 is a separator, symbols 6 and 7 are
A positive terminal and a negative terminal, reference numeral 8 denotes a connection lead, and reference numeral 9 denotes a battery case (container). Here, the light pole 1 and the negative electrode 3 are electrically connected by the connection conductor 8, and the electrolyte 4 is in contact with the light pole 1, the positive electrode 2, and the negative electrode 3. Light pole 1
Is attached to the battery case 9 after an electric field is applied perpendicularly to the surface and the electric field is removed to form a polarization plane structure. Hereinafter, the operation at the time of charging and discharging in this embodiment will be briefly described. At the contact interface with the electrolyte 4, the energy band of the light pole 1 is bent upward toward the electrolyte 4. Now, when the surface of the light pole 1 is irradiated with light energy such as the sun or a fluorescent lamp, electrons are excited in the conduction band of the energy band of the light pole 1 and holes are generated in the valence band.
This hole is carried toward the electrolyte 4 along the bending of the band, and causes an electrochemical oxidation reaction on the surface of the light pole 1. The electrons excited in the conduction band reach the surface of the negative electrode 3 through the connection conductor 8 and perform an electrochemical reduction reaction there. As a result, an oxidation product is accumulated near the light pole 1 and a reduction product is accumulated near the negative electrode 3, and the charging reaction of the secondary battery proceeds. On the other hand, at the time of discharging, an oxidation reaction proceeds on the surface of the negative electrode 3, and electrons generated at this time are supplied to a load connected to the positive electrode terminal 6 and the negative electrode terminal 7. The substance is reduced on the surface of the positive electrode 2 by the electrons. As described above, the energy conversion mode in the photochemical secondary battery of the present invention is direct conversion from light to electrochemical energy, and a voltage adjustment circuit or the like is not required. Thus, the battery structure can be simplified and downsized.

FIGS. 3 and 4 are diagrams for explaining the second embodiment of the present invention, wherein reference numeral 1 denotes a light pole made of a p-type semiconductor, and light pole 1 and positive electrode 2 are different from each other. Except for being electrically connected by the connection conductor 8, the other configuration is exactly the same as the first embodiment of the present invention shown in FIGS. 1 and 2.

FIG. 5 and FIG. 6 are diagrams for explaining the third embodiment of the present invention. This example is different from the first embodiment in that the light pole 1 is replaced with a first light pole 10 made of an n-type semiconductor,
The point is that it is divided into a second light pole 11 made of a p-type semiconductor, and the first light pole 10 and the second light pole 11 are insulated by an insulator layer 12. Further, the first light pole 10 and the second light pole 11 are arranged on the same plane, the first light pole 10 is the negative electrode 3, the second light pole 11 is the positive electrode 2, and the connection conductor 8 is 13 and electrically connected.

1 to 6 are examples in which the light receiving surface of the light pole 1 is not in contact with the electrolyte 4, but the electrolyte 4 is transparent, and the attenuation of light energy is almost negligible. If so, a structure in which the light receiving surface comes into contact with the electrolyte 4 and acts as a battery reaction surface as illustrated in FIG. 8 with reference to FIG. 2 may be employed. In this case as well, the situation is exactly the same, and the contact area between the light pole 1 and the electrolyte 4 increases, so that an improvement in conversion efficiency can be expected. Such a structure has similar functions and effects when applied to the example shown in FIGS. 3 to 6.

In any of the above embodiments, the light pole 1 is made of GaP, GaAs, AlA.
s, ZnS, AlSb, InP, CdS, GaSb, InAs, ZnTe, SiC, BaTiO ₃ , TiO ₂ ,
ZnO, Ag ₂ S, Ag ₂ Se, Ag ₂ Te, SnO ₂ , ThO ₂ , V ₂ O ₅ , Nb ₂ O ₅ , Ta ₂ O ₅ , Bi
₂ S ₃ , M ₀ O ₃ , WO ₃ , NaxWO ₃ , LixWO ₃ , KxWO ₃ (all x = 0 to
1), MnO ₂ , FeS ₂ , HgSe, Bi ₂ Se ₃ , PbCrO ₄ , PbOx (x = 0 to 1)
2), CdSe, PbSe (x > 0.1), Sb 2 Te 3, Cr 2 O 3, MnO 3, FeOx
(X <1), FeS, NiO, CoO, Pr 2 O 3, CuI, Ag 2 O, SnS, MoO 2, Bi 2
Compound semiconductors such as O ₃ , inorganic semiconductors such as Si, Ge, Se, anthracene, tetracene, pentacene, pyrene, perylene,
Ansanthrene, ovalene, coronene, biolanthrene, isobiolanthrene, pyranthrene, anthanthrone, biolanthrone, isobiolanthrone, pyranthrone, cyananthrone, isodanthrone black, flavanthrone, indanthrone, phthalocyanine, copper phthalocyanine, graphite, etc. condensed polycyclic aromatic compounds, polyacetylene, polyaniline, polyparaphenylene, Porichiiofen, PbZr Ti _{1-O 3} represented by PbZr _{0 3} TiO _{0 7} O ₃ having a polymer and ferroelectric polypyrrole, Pb _{1 -}
M ₂ NbO ₆ (x = 0 to 1, M = K, an alkali metal such as Na) or the like. The electrolyte 4 is acetonitrile,
It is composed of a non-aqueous solvent such as propylene carbonate, a base such as potassium hydroxide and sodium hydroxide, an acid such as sulfuric acid and acetic acid, an oxidation-reduction solution such as potassium ferrosyanide / potassium ferricyanide, and a mixed solution thereof. The battery case (container) 9 is not particularly limited as long as it is made of a material that is not affected by these electrolytes, such as an ABS resin or a fluororesin. In the light receiving surface portion of the battery case 9, the light pole 1 also serves as the battery case 9, or a transparent case material is formed. The connecting conductors 8 and 13 are made of copper wire or the like whose surface is not covered by the electrolyte 4 and is coated with an insulating material. The positive electrode 2 and the negative electrode 3 are made of platinum, palladium, iron, sodium, tin,
It is composed of copper, carbon, nickel, zinc, lead, cadmium, lithium and oxides thereof.

As described above, by adopting the structure shown in the first embodiment to the third embodiment, it is possible to charge with light having a much simpler structure and higher conversion efficiency than the conventional technology. A secondary battery can be provided.

〔The invention's effect〕

As described above, according to the present invention, the energy band is formed by immersing the light electrode (semiconductor electrode) in the electrolyte, and the light energy is converted from electrochemical energy to electrochemical energy. Or a structure in which the positive electrode or the negative electrode, which is one of the poles of the secondary battery, is electrically connected directly to the positive electrode or the positive electrode, and the positive electrode or the negative electrode, which is electrically connected to the light electrode, The charging reaction by light between the negative electrode and the discharging reaction between the positive electrode and the negative electrode were realized in one battery. This eliminates the need for a voltage adjustment circuit, which is indispensable in a conventional photovoltaic cell using a combination of a solar cell and a secondary cell, and simplifies the cell structure, thus greatly simplifying the production. is there.

[Brief description of the drawings]

FIGS. 1 and 2 show a first embodiment of the present invention. FIG. 1 is a schematic perspective view, and FIG.
FIG. 1 is a sectional view taken along line II-II, and FIGS. 3 and 4 show a second embodiment of the present invention.
The figure is a schematic perspective view, FIG. 4 is a sectional view taken along the line IV-IV of FIG. 3,
5 and 6 show a third embodiment of the present invention. FIG. 5 is a schematic perspective view, FIG. 6 is a sectional view taken along the line VI-VI of FIG. 7 and 8 show a fourth embodiment of the present invention. FIG. 7 is a schematic perspective view, FIG. 8 is a sectional view taken along line VIII-VIII of FIG. FIG. 9 is a schematic perspective view of a conventional secondary battery, FIG. 10 is an equivalent circuit diagram of the secondary battery shown in FIG. 9, and FIG. 11 is a schematic configuration of a conventional regenerative wet-type solar cell. FIG. 12 is a schematic configuration diagram of an oxygen-hydrogen generating battery using light. 1 ... Light electrode, 2 ... Positive electrode, 3 ... Negative electrode, 4 ... Electrolyte,
5 ... separator, 9 ... case, 10 ... first light pole,
11 ... second light pole, 12 ... insulator layer.

Continuation of front page (72) Inventor Toshio Horie 1-6, Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (56) References JP-A-63-19775 (JP, A) JP-A-56-93270 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H01M 14/00

Claims (5)

(57) [Claims] 1. A photoelectrode made of an n-type semiconductor at least one side of which is immersed in an electrolyte, a negative electrode immersed in the electrolyte and electrically connected to the photoelectrode, A cathode immersed in the electrolyte via a separator and electrically insulated from the photoelectrode, wherein the photoelectrode is made of a ferroelectric material and has a polarized surface structure A photochemical secondary battery, characterized in that: 2. A photoelectrode made of a p-type semiconductor at least one surface of which is immersed in an electrolyte; a positive electrode immersed in the electrolyte and electrically connected to the photoelectrode; A negative electrode which is immersed in the electrolyte via a separator and is electrically insulated from the light pole, wherein the light pole is made of a ferroelectric material and has a polarized surface structure formed. A photochemical secondary battery, characterized in that: 3. A first light pole made of an n-type semiconductor whose at least one surface is immersed in an electrolyte, and a second light electrode made of a p-type semiconductor whose at least one surface is immersed in an electrolyte. A negative electrode immersed in the electrolyte and electrically connected to the first light electrode and insulated from the second light electrode; immersed in the electrolyte via the negative electrode and a separator; And a positive electrode electrically connected to the second light pole and insulated from the first light pole. The light pole is made of a ferroelectric material and has a polarized surface structure. A photochemical secondary battery, which is formed. 4. The photochemical cell according to claim 1, wherein the photoelectrode is completely immersed in the electrolyte. 5. A battery comprising: a positive electrode immersed in an electrolyte; a negative electrode immersed in the electrolyte; and a photoelectrode made of a ferroelectric connected to at least one of the positive electrode and the negative electrode. A method for manufacturing a photochemical secondary battery, comprising: forming a polarization plane structure on the light pole by applying an electric field to the ferroelectric substance.