JPH01124975A - Photocell - Google Patents

Abstract

PURPOSE:To increase photocharge current and discharge current and to increase capacity density by forming basic structural elements with a negative current collector, a negative electrode, a solid electrolyte, a capacity electrode, a photo positive electrode, and a positive current collector. CONSTITUTION:Basic structural elements are formed with a negative current collector 1, a reversible copper negative electrode 2, a Cu<+> ion conductive solid electrolyte 3, a capacity electrode 4 comprising CuxMo6S8-y, a photoelectrode 5 comprising (Tix'Zr1-x')S2-y', and a positive current collector 6. To increase photocharge current and discharge current and to heighten charge acceptance, (Tix,Zr1-x')S2-y' is used as the photoelectrode and to improve the disadvantage of low capacity, CuxMo6S8-y is used as the capacity electrode, and both electrodes form a composite electrode. Disadvatages of small photocharge current and discharge current and low capacity density are eliminated, and a compact, lightweight cell capable of shortening charge time and durable to quick load change is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention has the functions of a solar cell and a secondary battery, and can be used as a permanent power source for electronic watches and calculators, as well as for photovoltaic power generation and power storage.
The present invention relates to photovoltaic cells that are widely used in various fields.

Conventional technology Until now, there was no commercially available power supply device that had both the functions of a solar cell and a secondary battery. The power generated by the solar cells is stored in a secondary battery, and when there is no light, such as at night, or when a large instantaneous current is required, the secondary battery supplies power to the load.

Recently, attempts have been made to use semiconductor electrodes to cause electrochemical reactions by injecting light to obtain useful substances or to store them as electricity. For example, using an n-TtOz photoelectrode and a platinum electrode, water is photolyzed and Ot gas is produced from the photoelectrode example.
Obtaining H2 gas from the platinum electrode side is one example of obtaining useful substances. Also, Mr. H, TRIBUTSCH is solid state ionics; 5OLID 5TAT
E l0NIC89/10 (1988), PP41-5
8, N0RIHHOLLAND PUBLISHING
COMPANY and STRUCTURE AND BONDING; 5 TRUC'r (JRE & BONDING.

49 (1982), PP127-175.5PR-IN
In GERVERLAG, nuzrsz-yl deintercalates C needle ions with light through electrical discharge.
demonstrated the possibility of photo secondary batteries using

Problems to be Solved by the Invention However, when an n-type Zr5z-y' photoelectrode is used with an aqueous electrolyte, in addition to the photocharging reaction, a photocorrosion reaction occurs with the solution, resulting in an extremely short lifespan. had.

The present applicant previously proposed a Cu+ ion conductive solid electrolyte Rb.
It has been found that photocorrosion can be prevented by using Cu4hscls,s as an electrolyte. However, ZrSgy
' has the disadvantage that both electronic conductivity and Cu ionoconductivity are low, and the charging/discharging current cannot be large, and the number of Cu+ ions that can be intercalated in ZrS, □' (corresponding to X in CuxZrSz-5/) is 0.15 However, it had the disadvantage of a low capacity density.

The present invention solves the above-mentioned conventional drawbacks of inability to increase photocharging current and discharging current and low capacity density, and provides a small and lightweight battery that shortens charging time and can withstand sudden loads. The purpose is to

Means for Solving the Problems The present invention has been made to achieve the above object, and includes a capacitive electrode consisting of a negative electrode current collector, a reversible copper negative electrode, a Cu + ion conductive solid electrolyte, and CuxMo6S8-y. and,
(T i / Z r, , l) The basic components are a photoelectrode made of S, -yl and a positive electrode current collector.

Function The present invention uses zrs2 as a photoelectrode in order to increase the photocharge current and discharge current and increase charge acceptance.
,; use ("xZr+-z)81,'. Its form is T iS 1-y h Z r
S! In order to improve the drawback of low capacitance density by using a mixture or a solid solution with CuXMO6S8-y as a capacitor electrode, the problem is solved by combining CuXMO6S8-y.

The photoelectrode of the present invention exhibits n-type semiconductivity and is C
It has the property of intercalating u ions through discharge. When these materials are exposed to light, light with energy greater than the band gap is absorbed, excites electrons into the conductive band, and generates holes in the conductive band. The energy level of the F edge of this conductive band is above the oxidation-reduction potential of copper, and the upper energy level of the conductive band is
If the energy level is below that at which ions intercalate in the semiconductor, the electrons in the conductive band will not react with Cu+ ions on the photoelectrode because of the energy barrier at the interface between the photoelectrode and the electrolyte. , passes through an external circuit to reach the counter electrode, where it returns the Cu+ ions to x@("u -1-x@e -+x-(C
Precipitate u. In addition, the holes generated in the conductive band are C
ux(Ti);ZrI,,')s2y', or CuxMO@Sa, is oxidized to produce Cux(TixZ
r+-x)S-+x-P■→x-cu+ (TjzZy
I-X) St-y or CuxMoss8. +X-P■4 x-(:u+Moa
Releases Cu+ ions like 5s-y. These reactions are similar to the charging reactions of photosecondary batteries. Whether photocharging is possible or not depends on the redox potential of Cu and Cux (T1xZr
+-2) It depends on whether the redox potential of St->7% or CuxMo6S8-y is included or not. In order to create such a state, it is better to have a larger breadth gap of the photoelectrode, but on the other hand, the more effectively the energy limit of the light that can be used shifts to the higher energy side and decreases. The use of a mixture or solid solution of Ti5ffi3: and zrs, -ρ as a photoelectrode is similar to the conventional ZrS,
-y has the effect of lowering the band gap of 1.68 eV, thereby increasing the efficiency of the photocharging reaction. The use of a mixture or solid solution also has the effect of significantly increasing the electronic conductivity and C♂ ionic conductivity of the photoelectrode over the Zrst horse, thereby increasing the charging and discharging current.

Both Tl5t-y and zrst-- have Cu reversibly in them.
The amount of ions that can be intercalated is extremely small, with X being 0.15. On the other hand, Cuz MOa Sa-y
When using, for example, y=0.1 and 0.9<x (1,9, 0,2≦y<0.
4, a large amount of Cu ions can be intercalated as shown in 0.2(

Embodiments Below, embodiments of the present invention will be explained in detail based on the drawings.

FIG. 1 is a basic configuration diagram of a photovoltaic cell using press molding in one embodiment of the present invention.

In the figure, 1 is a copper mesh of about 100 me that will be the negative electrode current collector, 2 is the electrolytic copper powder that will be the negative electrode active material, CutS and CL1+
3 is a molded mixture with an ion-conductive solid electrolyte, 4 is a molded product containing only a solid electrolyte, 4 is CuxMo, which becomes a capacitive positive electrode, 5
Mixed molded product of s-7 and electrolyte, 5 becomes a photoelectrode.
A mixture of ts, -y and ZrS2-y, or a mixed molded product of a solid solution and an electrolyte, 6 is graphite serving as a positive electrode current collector. Reference numerals 7 and 7' denote holding plates made of Bakelite plates for holding the photovoltaic battery, and the holding plate 7 has holes 8 for allowing light to enter the photoelectrode side.

At the bottom of a mold with a diameter of 13 mmφ, first place 10 which will become the negative electrode current collector 1.
A copper net of 0me' and 18mmφ is placed on top of it, and electrolytic copper powder of 0.0961 mm, Cu! SO
,064f.

C, + ion conductive solid electrolyte RbCu4IL6 C1
Add mixed powder of s, sO, OQ evenly and make 1001'4
Temporarily molded at a pressure of /cJ, and then electrolyte 8 was added for 0.2 s.
Then, as the photoelectrode 5, a Ti
S and ZrS.

and (A)0:1, [F])0.25:0.75
．． (C'IO, 50:0.50゜II))0.75:0
．． 25. ■ Mixed with a ratio of 1:O and ■ 0.75
: A solid solution of 0.04 and 0.01 F of electrolyte was added to each solid solution at a ratio of 0.25, and the whole was molded under a pressure of 8 tA to make pellets.

A positive electrode current collector 6 made of graphite with a hole for light incidence of 1Qmmφ was provided on the photoelectrode 5 of this pellet to form a battery, and after constant voltage charging of 0.55V, and an additional 10μA After discharging to a final voltage of 0.8 and obtaining a discharge curve, a 500 W Xe lamp was irradiated from a distance of 250 m, and the photocharging current was measured after 20 seconds. The light charge current was determined by irradiating light at 0.55V and 0.3V with the dark current being zero.

The results are shown in Figure 2 (discharge curve) and Figure 3 (light charging current).
It was like that. From now on, the X value of (Tix Zr+ y) S 2-y is 0.5
It is recognized that those in which ≦x<o and 8 have a large photo-charge current and an excellent discharge curve. ! is 0.75
The larger one has a better discharge curve, but 0.3V
If the battery is discharged to this point, photocharging will no longer be possible. We believe that this is because the bandgap becomes too narrow. If the X' value is smaller than 0.50, the photo-charge current will be small and the discharge curve will also be low. This is due to the photoelectrode electrons and Cu
This is thought to be due to the lower ion conductivity.

Therefore, a mold with a diameter of 13 mmφ was used as the negative electrode current collector 1, and the negative electrode 2 and electrolyte 3 were temporarily molded in the same manner as described above.
-y of y as (G) O, (FD O,1, (I) 0.
2, (J) of 0.4 was mixed with 0.04 f and 0.01 f of electrolyte powder and temporarily molded, and Ti5x-y' and Zr! -y' to 0.7
5: Add powder mixed with 0.01 (/) of electrolyte to 0.04 fl mixed at a ratio of 0.25, and add 8t/Cl.
In step 11, the pellets were formed into pellets. on this photoelectrode 5]
After assembling a battery by providing a positive electrode current collector 6 made of graphite with a hole for light incidence of Qmmφ and charging it at a constant voltage of 0.55V, the capacity was 200 μA, along with the above-mentioned document 0 in which the positive electrode 4 was not provided. A discharge curve was obtained when a constant current discharge was performed at 500 μA and 1 mA to a final voltage of 0.3 V, and finally, the photocurrent at O and aV was measured in the same manner as described above, and the samples were compared.

The results were as shown in FIG. 4 (discharge curve) and FIG. 5 (photocharging current). From these results, it can be seen that when the capacitive positive electrode 4 is attached, the discharge capacity increases by about 10 times due to K, and the drooping of the photo-charging current is also reduced because of this. It is also recognized that when the y value of Cu, MO6S8-y, -y of the capacitive positive electrode 4 is zero, the discharge capacity decreases.

Therefore, the capacitive positive electrode 4 consisting of CuXMO6S8-y, -7
It is preferable that x = 2 + 0-1≦y≦0.4, and by combining it with the photoelectrode 5, the capacity density can be significantly increased. (TjX'Zr l
−)! ') The optical poles 5 and 12 consisting of S 2-chi are 0.
It is desirable that 5≦x'<0.8 p non 0.1.

FIG. 6 shows a cross-sectional view (a) and a top view of a photovoltaic cell using a thin (thick) film, which is another embodiment of the present invention.

Figure <a) is a sectional view taken along line xx' of figure Φ). The same parts as in FIG. 1 are given the same numbers.

In the figure, graphite paste, which will become the positive electrode current collector 6, is screen printed on a glass substrate 7, excluding the incident light area, and heated to 200°C.
Baking was carried out for 30 minutes. Even if a film of about 2 μm is formed by sputtering instead of screen printing, the same current collecting effect can be obtained. Next, TiS2 and ZrS2, which will become the photoelectrode 5
■5oooCi with magnetron sputtering with a ratio of 0.75: 0.25-y to the bow
IL.

Cut Mos S ? , 8 was deposited to a thickness of 1 μm using magnetron sputtering. Next, RbCu4ICls,s, which will become the electrolyte 8, was applied by vapor deposition to a thickness of about 10μ. Furthermore, it becomes the active material of negative electrode 2 ('u and Cn2S
A mixture with a ratio of 0.6:0.4 was deposited to a thickness of about 1 μm by magnetron sputtering. Finally, the negative electrode current collector 1 is formed ('u) with a thickness of 1μ by vapor deposition, and the connection of each cell is completed. 8 is a layer of epoxy resin that covers the cells. In this way, the l1ff angle ( Exposure section 8.9
ff angle) 4 cells were connected in series, and a t-shaped one was made.

A 2.2 V Zener diode 9 was connected to the photo secondary battery thus produced, and the battery was subjected to the following experiment. The reason for using the Zener diode 9 is to prevent overcharging (2.
This is to prevent overcharging (if it exceeds 2 μ, it will lead to overcharging, which will generate electricity and shorten the life of the battery), and to enable optical charging even when there is no load.

In the experiment, first, a 500 W 5 minutes after the start of photocharging) was determined.

The results were as shown in FIG. From now on, when the photoelectrode becomes as thin as about 5000A, light reaches the capacitive positive electrode, which is a P-type semiconductor, from the photoelectrode, which is an n-type semiconductor, and the photocharging speed decreases, so a battery can be constructed with a thin (thick) film. It can also be seen that it is necessary to use a photoelectrode with a thickness of 1 μm or more in this case.

As mentioned above, TiS2. which is an n-type semiconductor. ;&ZrS
, ' by using a photocathode consisting of a mixture or solid solution of ZrS2, which was provided by one of the inventors.
The efficiency of photocharging is higher than that of a secondary battery using , ; as a photoelectrode, and the charging and discharging current can be increased,
By combining a capacitive positive electrode made of Cu2M0g5s□ with a photoelectrode, the capacitance density can be significantly increased.

Effects of the Invention In short, the present invention provides a photovoltaic cell whose basic components are a negative electrode current collector, a negative electrode, a solid electrolyte, a capacitive positive electrode, a photoelectrode, and a positive electrode current collector, and which increases the photocharging current and discharging current. It has the advantage of significantly increasing capacity density, shortening charging time, being able to withstand sudden loads, and being smaller and lighter.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a photovoltaic cell using press molding according to an embodiment of the present invention, FIG. 2 is a characteristic diagram showing the effect of the photoelectrode of the same embodiment on the discharge curve, and FIG. 3 is a diagram showing the effect of the photoelectrode of the same embodiment on the discharge curve. FIG. 4 is a characteristic diagram showing the effect of the photoelectrode on the photocharging current; FIG. 4 is a diagram showing the effect on the discharge curve of the capacitive positive electrode of the same example; FIG.
The figure shows the effect of the capacitive positive electrode of the same embodiment on the photocharging current, and FIG. 6 shows the structure of a thin film photovoltaic cell in another embodiment of the present invention, and FIG. 6(a) is a cross-sectional view. Figure, 6th
Figure tb) is a plan view, and Figure 7 is a characteristic diagram showing the effect of the thickness of the photoelectrode on the photocharging current of the same example. 1... Negative electrode current collector, 2... Negative electrode, 8... Electrolyte,
4... Capacitive positive electrode, 5... Photoelectrode, 6... Positive electrode current collector. Name of agent: Patent attorney Toshio Nakao and 1 other person
111 to 7 holding slope 7 Hohiro Ginabeko voltage (VJ Figure 3 Ti52-y 25 50 15 Z
h 52-(Relationship (771s/zo, Jimako Voltage CV) ゝFigure 5(, uy Mob 5s-y M Ca2 No45
S deficiency of g-1 (v value) 116 Figure 7 Thickness of nine electric scrapers (pm)

Claims (4)

[Claims] (1) Negative electrode current collector, reversible copper negative electrode, Cu^+ ion conductive solid electrolyte, capacitive positive electrode consisting of Cu_xMO_6S_8_-_y (however, 0.1≦y≦0.4), (Ti_x
'Zr_1_-_x') S_2-y' (However, 0.5≦
A photovoltaic cell characterized in that its basic components include a photocathode and a cathode current collector, each of which has the following properties: x<0.8, y≧0.1. (2) A mixed molded product of Cu^+ ion-conductive solid electrolyte, electrolytic copper powder, and Cu^2S as a reversible copper negative electrode, and the Cu^+ ion-conductive solid electrolyte and Cu_x as a capacitive positive electrode.
A mixed molded product with Mo_6S_8_-_y, the Cu^+ ion conductive solid electrolyte and (Ti_x'Z
2. The photovoltaic cell according to claim 1, characterized in that a molded mixture of the negative electrode current collector and the photopositive electrode current collector is made of copper and graphite is used as the photopositive electrode current collector. (3) Copper film as negative electrode current collector, copper powder and Cu_ as negative electrode
Mixed membrane with 2S, Cu^+ ion conductive solid electrolyte membrane as electrolyte, Cu_xMo_6S_8_ as capacitive positive electrode
−_y film, as a photopositive electrode (Ti_x'Zr_1_-_
2. The photovoltaic cell according to claim 1, wherein a film of x')S_2_-_y' and a graphite film provided at the periphery of the photoelectrode as a positive electrode current collector are sequentially laminated. (4) The thickness of the photopositive electrode is set to such a level that all incident light is absorbed by this layer and does not reach the capacitive positive electrode (1 μ < δ). The photovoltaic cell according to any one of the above.