JPH07118333B2 - Solar battery - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solar battery that uses a solid electrolyte secondary battery to store electric power obtained from a solar cell that uses photovoltaic power of a semiconductor p / n junction. More specifically, the present invention relates to a novel solar battery in which Cu ₂ S, which is a p-type semiconductor forming the p / n junction, also serves as the positive electrode of the solid electrolyte secondary battery using a Cu ⁺ ion conductive solid electrolyte.

2. Description of the Related Art Solar cells that use the photovoltaic power of semiconductor p / n junctions do not have a power storage function by themselves, so solar cells alone can supply power only while light is being irradiated.

Further, in order to supply electric power even when there is no light irradiation, the solar cell is conventionally most used as a solar power storage device in combination with a secondary battery such as a nickel-cadmium battery. As a secondary battery used for such a purpose, in place of a nickel-cadmium battery using a conventional liquid electrolyte, etc., all the battery constituent elements are solid, and in principle, there is no liquid leakage, a thin type, By using a solid electrolyte secondary battery that can be easily miniaturized, a number of unprecedented advantages such as integration of solar cells and secondary batteries and sharing of packages can be obtained.

The present inventors have previously proposed a solar power storage device in which, of such solid electrolyte secondary batteries, a secondary battery using a Cu ⁺ ion conductive solid electrolyte and a solar battery are combined. This device has an advantage that a device having excellent storage efficiency can be obtained by suitably combining the number of single cells of a solar battery and the number of single cells of a secondary battery.

Problems to be Solved by the Invention However, such a solar power storage device includes two types of a secondary battery including a positive electrode, a negative electrode, and an electrolyte, and a solar cell including a semiconductor p / n junction. It is a composite of independent elements, and each element manufactured by an independent manufacturing process is housed in the same package.
In addition to the three components of the positive electrode, the negative electrode, and the solid electrolyte, a total of five components of p-type and n-type semiconductors are required as constituent elements or materials. Moreover, in order to obtain a suitable combination of voltages, a plurality of elements are required for each.

When expecting high reliability in the finished device, it is desirable that the number of constituent elements is as small as possible, and it is desirable that the solar cell and the secondary battery are configured by one continuous manufacturing process.

Means for Solving the Problems In the present invention, the p-type semiconductor that constitutes the solar cell uses Cu ₂ S, which can also act as the positive electrode of the secondary battery, as the positive electrode, so that the minimum required five constituent elements are provided. To provide four solar storage batteries. Further, it becomes possible to construct the solar cell and the secondary battery in one continuous manufacturing process.

That is, the solar battery according to the present invention uses Cu ₂ S, which is a p-type semiconductor, as a positive electrode, a Cu ⁺ ion conductive solid electrolyte,
Electromotive force consisting of negative electrode mainly composed of metallic copper is about 0.3-0.4V
Of the solid electrolyte secondary battery, and a p / n junction formed by the junction of CdS, which is an n-type semiconductor, and Cu ₂ S, which is a p-type semiconductor that also acts as the positive electrode. It is composed of a power generation unit (b) whose electric power is 0.50V. Cu ₂ S is formed on the CdS layer, and Cu is formed on top of it.
⁺ Ion conductive solid electrolyte layer and four layers of negative electrode layer mainly composed of metallic copper (hereinafter abbreviated as Cu negative electrode layer), CdS layer and C
The solar battery according to the present invention is formed by electrically connecting with the negative electrode layer. The Cu negative electrode layer is formed in a mesh shape, a lattice shape, a comb shape, or the like so that light can reach the p / n junction.

As the Cu ⁺ ion conductive solid electrolyte, a Cu ⁺ ion conductive solid electrolyte represented by the general formula RbCu ₄ I _{2 -X} Cl _{3 + X} (x = 0.25 to 0.75) is suitable in consideration of light transmittance. Used.

Fig. 3 shows RbC where x = 0.5 in the above-mentioned general formula formed by the resistance heating method on a quartz glass plate under a vacuum of 5 × 10 ^-5 Torr.
FIG. 4 shows the optical absorption spectrum of a u ₄ I ₁₅ Cl ₃₅ film (thickness: 3.5 μ).

It absorbs at 450 nm or less and it is difficult for sunlight to pass the ultraviolet light, but it can be used without any problems in practical use.
Further, the range of x = 0.25~0.75, RbCu ₄ decomposition voltage of I _2-X Cl _{3 + X} is about 0.6V, a voltage of 0.5V from the power generating section (b) over a long period of time storage unit ( Even if it is applied for charging a), there is no possibility of deterioration of the electricity storage unit (a) due to decomposition of the Cu ⁺ ion conductive solid electrolyte layer.

Next, the electrical connection between the CdS layer and the Cu negative electrode is, if necessary,
This can be done through a diode having a forward voltage drop of about 0.1 to 0.2V. As such a diode, a germanium diode can usually be used. Connection is CdS
The direction in which electrons flow from the layer toward the Cu negative electrode layer is the forward direction. By doing so, it is possible to effectively prevent the electricity stored in the power storage unit (a) from leaking through the power generation unit (b) when there is no light irradiation.

When operating light is radiated, the voltage part generated in the power generation part (b) is 0.
The 50V electrons are sent to an external load, where they are consumed and used, and some of them reach the Cu negative electrode through the electrical connection between the CdS layer and Cu negative electrode, where they are liberated from the positive electrode layer Cu ₂ S. Then, it combines with Cu ⁺ ions that have passed through the Cu ⁺ ion conductive solid electrolyte layer to prepare Cu as a Cu negative electrode layer. When light is not applied, the electricity thus stored in the power storage unit (a) is supplied to the external load from the power storage unit (a) in which the Cu ₂ S layer is the positive electrode and the Cu negative electrode layer is the negative electrode. can do.

Hereinafter, description will be made with reference to examples.

Example FIG. 1 is a schematic sectional view showing the structure of a solar battery which is one of the examples of the present invention.

The thickness of the copper (Cu) foil 1 with a thickness of 0.2 mm is 10 by vacuum deposition.
Forming a CdS layer 2 having a size of 5 × 5 mm square and further immersing a Cu ₂ S layer 3 having a thickness of 0.1 μ on the CdS layer 2 in a CuCl solution to replace Cd on the surface with Cu. To form. Then thickness 3.
A Cu ⁺ ion conductive solid electrolyte layer 4 composed of ₅ μm of RbCu ₄ I _1.5 Cl _3.5 is formed on the Cu ₂ S layer 3 by a vacuum deposition method, and further, a Cu composed of a metal copper film having a thickness of 0.3 μm is formed thereon. The negative electrode layer 5 is formed in a grid shape. 6 is a glass plate having conductive indium tin oxide thin films 6a and 6b on one surface, and Cu
Negative electrode layer 5 and the conductive thin film 6a, and Cu ₂ and a part and the conductive thin film 6b of S 'layer are arranged so as monkey respectively electrically connected.

6c is an electrical connection terminal formed by pt paste on the Cu ₂ S layer 3 in order to electrically connect the Cu ₂ S layer 3 and the conductive thin film 6b. The glass plate 6 and the copper foil 1 are adhered by an epoxy resin adhesive 7. Reference numeral 8 denotes a germanium diode, which is connected so that electrons flow from the CdS layer 2 to the Cu negative electrode layer 5 as indicated by the circuit symbol of the diode in the figure. Reference numeral 9 is a pole terminal, and 10 is a pole terminal.

Fig. 2 shows that such a solar battery was exposed to sunlight for 30 minutes and then passed through pole terminal 9 and pole terminal 10 in the dark.
Pole terminal 9 when discharged at a constant current of 50μA for 30 minutes at ℃
3 shows a voltage change between the pole terminal 10 and the pole terminal 10.

In the figure, the 10th and 100th cycles are the terminals at the time of discharging after repeating the charging / discharging cycle of charging for 30 minutes with sunlight for 30 minutes and discharging at 50μA for 30 minutes. It shows the change of the voltage between the two. 100
It gives almost the same initial discharge characteristics as the discharge characteristics even after cycling.

EFFECTS OF THE INVENTION As described above, according to the present invention, Cu ₂ S, which is a p-type semiconductor of a solar power generation unit, is caused to act as a positive electrode of a power storage unit including a solid electrolyte secondary battery, so that the number of components is increased. It is possible to provide a solar storage battery in which the number of solar cells is reduced from the conventional five to four.

[Brief description of drawings]

FIG. 1 is a schematic view showing a cross-sectional structure of a solar storage battery which is one of the embodiments of the present invention, FIG. 2 is a view showing discharge characteristics of the solar storage battery of the embodiment, and FIG. 3 is the solar light of the present invention. It is a figure which shows the light absorption spectrum of the Cu ⁺ ion conductive solid electrolyte membrane used for a storage battery. 1 ... Copper foil, 2 ... CdS layer, 3 ... Cu ₂ S layer, 4 ... Cu ⁺ ion conductive solid electrolyte layer, 5 ... Cu negative electrode layer.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-59-107577 (JP, A) JP-A-60-264060 (JP, A) Japanese Patent Application No. 55-143642 (No. Contents of the description and drawings attached to the application of Microfilm (JP, U) Description of the specification and drawings attached to the application of Japanese Patent Application No. Sho 60-194150 (No. Sho 62-102266) Micro film (JP, U)

Claims (3)

[Claims] 1. A power storage unit comprising: (a) a p-type semiconductor Cu ₂ S as a positive electrode, a Cu ⁺ ion conductive solid electrolyte, and a negative electrode mainly containing metallic copper; and (b) an n-type semiconductor CdS. And a power generation section having a p / n junction formed by joining with the p-type semiconductor Cu ₂ S which is the positive electrode of the power storage section (a), and is mainly composed of the n-type semiconductor CdS and the metallic copper. A solar storage battery, which is electrically connected to a negative electrode. 2. An n-type semiconductor CdS and a negative electrode mainly composed of metallic copper are electrically connected via a diode with a forward direction of electrons flowing from the n-type semiconductor CdS to a negative electrode mainly composed of metallic copper. The solar storage battery according to claim 1, wherein the solar storage battery is connected to. 3. A Cu ⁺ ion conductive solid electrolyte is a compound represented by the general formula: RbCu ₄ I _{2 -X} Cl _{3 + X} (x = 0.25 to 0.75). Item 2. The solar battery according to Item 2 or Item 2.