JPH1174002A - Secondary battery integrated with solar cell and watch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To thin the whole combination of a solar cell and a secondary battery without decreasing charge and discharge capacity of the secondary battery, by using a substrate having a conductive surface of the solar cell as an outer covering of a positive electrode or a negative electrode of the secondary battery, and combining the solar cell with the secondary battery. SOLUTION: A solar cell 10 such as amorphous solar cell is arranged on a substrate 11 such as metal sheet through an insulating layer 12. A negative electrode 21 such as graphite and a positive electrode 23 such as metal oxide are provided so as to sandwich a solid electrolyte 22 formed by containing a solute such as Li PF6 in a polymer material such as polyethylene oxide and an insulating packing 25 is provided around them, then a secondary battery 20 is provided. This secondary battery 20 is connected to the solar cell 10 using the substrate 11 of the solar cell 10 as a negative electrode outer covering, further a positive electrode outer covering 24 is provided. This secondary battery of a solar cell integrated type is fitted in a movement 40 of a watch such as a wrist watch together with a control circuit 30. Thus, it is possible to thin the thickness of the watch using the combined solar cell and the secondary battery as a power source.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a solar cell-integrated secondary battery in which a solar cell and a secondary battery are combined, and a timepiece using such a solar cell-integrated secondary battery.
In particular, a solar cell-integrated secondary battery and a solar cell-integrated secondary battery in which the thickness of the above-described solar cell-integrated secondary battery is reduced so that the solar cell-integrated secondary battery can be suitably used as a power source in a watch such as a wristwatch The present invention relates to a timepiece using a watch.

[0002]

2. Description of the Related Art In recent years, wristwatches and the like have used a solar cell as a power source. However, when a watch is operated only by electric power generated by the solar cell, it becomes dark. Since the clock stops at a place or the like, as shown in JP-A-62-203525, a solar battery and a secondary battery are combined, and the power generated by the solar battery is charged into the secondary battery. In a dark place or the like, a watch has been developed in which the timepiece is operated by discharging the secondary battery.

However, the above-mentioned publication discloses that a solar cell and a secondary battery are provided separately by simply combining a solar cell and a secondary battery, and the charge and discharge of the secondary battery are controlled. Control circuit is also provided separately, so that when a combination of such a solar cell and a secondary battery is used as a power source for a watch such as a wristwatch, the energy density of the secondary battery is reduced, and In order to obtain a charge / discharge capacity, there has been a problem that the thickness of the timepiece is increased.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems when a solar cell and a secondary battery are combined and used as a power source for a timepiece such as a wristwatch. When using a combination of a solar cell and a secondary battery, the thickness of the combination of the solar cell and the secondary battery can be reduced without reducing the charge / discharge capacity of the secondary battery. It is an object of the present invention to reduce the thickness of a watch when a combination of the battery and a secondary battery is used as a power source of a watch such as a wristwatch.

[0005]

According to a first aspect of the present invention, there is provided a solar cell-integrated secondary battery in which a solar cell and a secondary battery are combined to solve the above-mentioned problems. In the body type secondary battery, a substrate of a solar cell having a conductive surface was used as an outer package of the positive electrode or the negative electrode in the above secondary battery.

Here, in the solar cell-integrated secondary battery according to the first aspect, since the substrate in the solar cell is used as the positive electrode or the negative electrode in the secondary battery as described above, the positive electrode in the secondary battery is used. Alternatively, there is no need to separately provide an outer package of the negative electrode, and the overall thickness of the solar cell integrated secondary battery can be reduced.

Here, as the solar cell used in the above-described solar cell integrated type secondary battery, a commonly used known solar cell can be used, and any structure such as amorphous, single crystal, and polycrystalline can be used. It may be a solar cell. Then, an appropriate number of the solar cells are connected in series, so that the generated voltage corresponds to the charging voltage of the secondary battery.

The substrate of the solar cell may be any substrate having a conductive surface as described above. For example, a substrate composed of a thin metal plate or a plastic film provided with a metal film may be used. Can be used.

On the other hand, as the secondary battery used for the above-mentioned solar battery integrated type secondary battery, a commonly used known battery can be used. In order to use and reduce the thickness, a flat coin-shaped one is generally used.

Further, when a solid electrolyte secondary battery using a solid electrolyte is used for the secondary battery as in the solar battery integrated secondary battery according to the second aspect of the present invention, the thickness of the secondary battery is further increased. When a solid electrolyte secondary battery using lithium as its active material is used, a sufficient charge / discharge capacity can be obtained even when the thickness of the secondary battery is reduced.

Here, in the solid electrolyte secondary battery using lithium as an active material, as a cathode material, for example, LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ , which can occlude and release lithium ions, can be used. LiM
_{nO 2, LiM 1X M 2y O} Z (M 1, M 2 is a transition metal, x, y, z are an arbitrary real number.) lithium transition metal compounds represented by is suitably used.

Examples of the negative electrode material include carbon materials such as graphite, coke, and polymer fired bodies capable of inserting and extracting lithium ions, lithium metal, alloys of lithium and other metals, metal oxides, and metal oxides. Sulfides and the like are used.

As the solid electrolyte, for example, a polymer material such as polyethylene oxide, polypropylene oxide or polyethylene oxide derivative contains LiPF ₆ , L
Use a solute containing a solute composed of a lithium salt such as iClO _4, a gel-like one impregnated with a non-aqueous electrolyte in which the above solute is dissolved in an organic solvent, or an inorganic solid electrolyte such as Li ₂ S Examples of the organic solvent that can dissolve solutes include ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, cyclopentanone, sulfolane, dimethyl sulfolane, 3-methyl-1,3-oxazolidin-2-one. Γ-butyrolactone, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, butyl methyl carbonate, ethyl propyl carbonate, butyl ethyl carbonate, dipropyl carbonate, 1,2-dimethoxyethane, tetrahydrofura , 2-methyltetrahydrofuran, 1,3-dioxolan, methyl acetate, ethyl acetate and the like can be used alone or in combination of two or more.

When the positive electrode of the secondary battery is brought into contact with the solar cell substrate, the positive electrode may react with the solar cell substrate. When a negative electrode of a secondary battery is brought into contact with a substrate of a solar cell as in a secondary battery, the negative electrode and the substrate of the solar cell do not react with each other and can be used stably.

Further, when a metal oxide is used as the negative electrode material of the negative electrode of the secondary battery as in the solar cell integrated type secondary battery according to claim 3 of the present invention, a carbon material, metal lithium, or the like is used as the negative electrode material. The contact with the substrate of the solar cell is improved as compared with the case where the solar cell is used, and the current can be appropriately collected without using the current collector. The cycle characteristics of the secondary battery are improved. Here, as such a metal oxide, lithium titanate, lithium niobate, lithium stannate, lithium ferrate, lithium silicate and the like can be used.

When the above-described solar cell-integrated secondary battery is used as a power source for a timepiece such as a wristwatch, the solar cell-integrated secondary battery is formed to be thin as described above.
The thickness of the entire timepiece using the solar cell-integrated secondary battery can also be reduced.

Further, when a control circuit for controlling charging and discharging of the secondary battery is provided integrally with the secondary battery on the substrate of the solar cell, the thickness of the entire timepiece can be further reduced.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a solar cell integrated secondary battery according to an embodiment of the present invention and a timepiece using the solar cell integrated secondary battery will be specifically described, and a comparative example will be described.
It is clear that the timepiece using the solar cell-integrated secondary battery described in this embodiment can be reduced in thickness.

(Embodiment 1) In this embodiment, FIG.
As shown in the figure, the product is made of SUS and has a diameter of 20 mm and a thickness of 0.1 mm.
The solar cell 10 was provided on the substrate 11 having a thickness of 2 mm with the insulating layer 12 interposed therebetween.

In providing the secondary battery 20 to be integrated with the solar cell 10, a positive electrode, a negative electrode and a solid electrolyte prepared as described below were used.

[Preparation of Positive Electrode] In preparing a positive electrode, LiCoO ₂ was used as a positive electrode material.
₂ , artificial graphite as a conductive agent, and polyvinylidene fluoride as a binder in a weight ratio of 80:10:10, and N-methyl-2-pyrrolidone (NMP) was added thereto to form a slurry. The slurry was applied to one surface of an aluminum foil as a positive electrode current collector by a doctor blade method, and dried in a vacuum at 150 ° C. for 2 hours to produce a positive electrode.

[Preparation of Negative Electrode] In preparing the negative electrode, the negative electrode material was prepared by adding a spacing d002 between lattice planes (002).
Is 3.35 °, and the crystallite size Lc in the c-axis direction is 10
Using a carbon powder of 00 ° or more, this carbon powder and polyvinylidene fluoride as a binder are mixed at a weight ratio of 90:10, and NMP is added thereto to form a slurry, and this slurry is used as a negative electrode current collector. One side of the copper foil was applied by a doctor blade method, and this was vacuum-dried at 150 ° C. for 2 hours to produce a negative electrode.

[Preparation of Solid Electrolyte] In preparing a solid electrolyte, polyethylene oxide having a molecular weight of 20,000 to 100,000 was vacuum-dried at 110 ° C. for 10 hours, and then lithium hexafluorophosphate LiPF was added thereto.
₆ was impregnated with a solution of 1 mol / l in dimethyl carbonate, and then vacuum-dried at 110 ° C. for 2 hours to remove dimethyl carbonate. The weight ratio of polyethylene oxide and LiPF ₆ was 95: 5. A solid electrolyte having a ratio was prepared.

Then, on the substrate 11 of the solar cell 10, the negative electrode 21, the solid electrolyte 22, and the positive electrode 22 formed as described above are provided on the surface opposite to the surface on which the solar cell 10 is provided via the insulating layer 12. 23, and a cathode case 24 made of aluminum is provided on the cathode 23. Between the cathode case 24 and the substrate 11, the anode 21 and the solid electrolyte 22 stacked as described above are provided.
And an insulating packing 25 made of polyethylene resin around the positive electrode 23, and the insulating packing 25 is welded to the positive electrode package 24 and the substrate 11 at 150 ° C. to produce a solar cell integrated secondary battery. The packing 25 electrically insulates the positive electrode package 24 from the substrate 11 and seals the secondary battery 20.

In this embodiment, a solar cell integrated secondary battery manufactured as described above is used, and the remaining space provided with the solar cell integrated secondary battery is A control circuit 30 for controlling charging and discharging and a clock movement 40 are provided. In this embodiment, the control circuit 30 is in contact with the substrate 11, but the control circuit 30 is not formed integrally with the substrate 11.

As described above, the solar cell 10 and the secondary battery 2
When the control circuit 30 and the movement 40 are separately provided, the total thickness of the control circuit 30 and the movement 40 is 3.0 m.
m.

(Embodiment 2) In this embodiment, FIG.
As shown in FIG. 7, a solar cell integrated type secondary battery is manufactured in the same manner as in the above-described Example 1, while the solar cell 1
The control circuit 30 for controlling the charging and discharging of the secondary battery 20 is integrally formed on the same surface of the substrate 11 as the surface on which the secondary battery 20 is provided, and the clock movement 4 is provided in the remaining space.
0 was provided.

Thus, the solar cell 10 and the secondary battery 2
0 and the control circuit 30 are integrally formed, and when a clock movement 40 is provided separately from the control circuit 30, the overall thickness is set to 2.
The thickness could be further reduced to 6 mm.

Comparative Example 1 In this comparative example, FIG.
As shown in FIG.
, A clock movement 40 is integrally provided on the surface opposite to the surface on which the solar cell 10 is provided via the insulating layer 12, and the secondary battery 20 and the charging / discharging of the secondary battery 20 are provided via the clock movement 40. And a control circuit 30 for controlling the control.

Here, in this comparative example, when providing the secondary battery 20 as described above, the above-described first embodiment was used.
Unlike the case of the above, it is necessary to provide the negative electrode package 26, and the negative electrode 21, the solid electrolyte 22, and the positive electrode 23 are laminated between the negative electrode package 26 and the positive electrode package 24. The thickness of the secondary battery 20 was larger than that of each of the above embodiments.

When the solar cell 10, the clock movement 40, the secondary battery 20, and the control circuit 30 are provided as described above, the overall thickness is 5.0 mm, It was thicker than that.

(Embodiment 3) In this embodiment 3, as shown in FIG. 4, the solar cell 10 is provided on an SUS substrate 11 with an insulating layer 12 interposed therebetween, as in the above-described embodiment 1. did.

In providing the secondary battery 20 to be integrated with the solar cell 10, a positive electrode, a negative electrode and a solid electrolyte prepared as described below were used.

[Preparation of Positive Electrode] In preparing the positive electrode, LiCoO ₂ was used as a positive electrode material.
₂ , a conductive agent, carbon, and a binder, polytetrafluoroethylene, were mixed at a weight ratio of 80:10:10 to prepare a positive electrode mixture.
A positive electrode was produced by pressing into a disk having a thickness of 400 μm and a thickness of 400 μm without using a positive electrode current collector.

[Preparation of Negative Electrode] In preparing the negative electrode, graphite was used as a negative electrode material, and this graphite powder and polytetrafluoroethylene as a binder were mixed at a weight ratio of 90:10 to prepare a negative electrode mixture. This negative electrode mixture was pressure-formed into a disk having a diameter of 14 mm and a thickness of 400 μm, and a negative electrode was produced without using a negative electrode current collector.

[Preparation of Solid Electrolyte] In preparing a solid electrolyte, lithium hexafluorophosphate LiPF was added to 1 kg of polyethylene oxide heated and melted.
₆ was added at a rate of 1 mol, and this was cured to produce a disk-shaped solid electrolyte having a diameter of 14 mm and a thickness of 100 μm.

On the substrate 11 of the solar cell 10, the negative electrode 21, the solid electrolyte 22, and the positive electrode 22 formed as described above are provided on the surface opposite to the surface on which the solar cell 10 is provided via the insulating layer 12. 23, and a disc-shaped positive-electrode casing 24 made of SUS having a diameter of 20 mm and a thickness of 100 μm is provided on the positive electrode 23, and between the positive-electrode casing 24 and the substrate 11. An insulating packing 25 made of polyethylene resin is disposed around the negative electrode 21, the solid electrolyte 22, and the positive electrode 23 stacked as described above, and the insulating packing 25 electrically insulates the positive electrode package 24 and the substrate 11. At the same time, the insulating packing 25 was welded to the positive electrode case 24 and the substrate 11 to seal the secondary battery 20, thereby producing a solar cell integrated secondary battery.

In this embodiment, in the solar cell integrated type secondary battery manufactured as described above, the secondary battery 20 is provided in contact with the portion of the solar cell 10 where the secondary battery 20 is not provided. 20 is provided with a control circuit 30 for controlling charging and discharging.

Comparative Example 2 In this comparative example, FIG.
As shown in FIG.
In providing the secondary battery 20 so as to be in contact with the substrate 11 of the solar cell 10, between the substrate 11 of the solar cell 10 and the negative electrode 21,
S in the shape of a disk with a diameter of 20 mm and a thickness of 100 μm
A solar cell integrated secondary battery was produced in the same manner as in Example 3 except that a US-made negative electrode case 26 was provided.

When the energy densities of the secondary batteries 20 in the solar cell integrated secondary batteries of the above-mentioned Example 3 and Comparative Example 2 are compared, in the secondary battery 20 of Example 3, the negative The energy density is higher than that of the secondary battery 20 of Comparative Example 2 by the amount not provided, whereas the energy density of the secondary battery 20 of Comparative Example 2 was 100 Wh / l. Example 3
Secondary battery 20 has an energy density of 150
Wh / l, and the energy density was improved about 1.5 times.

(Examples 4 to 9) In these examples, only the negative electrode materials used for the secondary battery 20 in the fabrication of the solar cell integrated type secondary battery in the above-mentioned Example 3 are shown in Table 1 below. The solar cell integrated secondary batteries were fabricated in the same manner as in Example 3 except for the following changes.

Then, in each of the solar cell integrated type secondary batteries of Example 3 and Examples 4 to 9 above, each secondary battery 20 was charged by the solar cell 10 to a charge end voltage of 2.5 V. Thereafter, the battery was discharged to a discharge end voltage of 1 V, and such charge / discharge was repeated. The number of cycles until the discharge capacity became half of the initial discharge capacity was obtained. The results are shown in Table 1 below. .

[0043]

[Table 1]

As is apparent from these results, in the secondary battery 20 of the solar cell integrated type secondary battery, when the negative electrode current collector is not used for the negative electrode 21, lithium titanate and lithium niobate are used as the negative electrode material. When a metal oxide comprising lithium, lithium stannate, lithium ferrate, and lithium silicate is used, the cycle characteristics of the secondary battery 20 are improved as compared with the case where a carbon material such as graphite or metal lithium is used as the negative electrode material. Was.

[0045]

As described in detail above, in the solar cell integrated secondary battery according to the first aspect of the present invention, the substrate in the solar cell is used as the outer package of the positive electrode or the negative electrode in the secondary battery. In addition, it is not necessary to separately provide the outer package of the positive electrode or the negative electrode in the secondary battery, and the overall thickness of the solar cell integrated secondary battery can be reduced.

Further, when a solid electrolyte secondary battery is used as the secondary battery as in the solar cell integrated secondary battery according to the second aspect of the present invention, the thickness of the secondary battery can be further reduced. When a solid electrolyte secondary battery using lithium as its active material is used, a sufficient charge / discharge capacity can be obtained even when the thickness of the secondary battery is reduced.

Further, when the negative electrode of the secondary battery is brought into contact with the solar cell substrate as in the solar cell integrated secondary battery according to the third aspect of the present invention, the negative electrode reacts with the solar cell substrate. The use of a metal oxide as the negative electrode material of the negative electrode in this secondary battery makes the secondary battery more secondary than the case where a carbon material or metal lithium is used as the negative electrode material. The cycle characteristics of the battery were improved.

When the above-described solar cell-integrated secondary battery is used as a power source for a timepiece such as a wristwatch, the thickness of the entire timepiece using the solar cell-integrated secondary battery can be reduced. In addition, when a negative electrode of a secondary battery is brought into contact with a substrate of a solar cell and a metal oxide is used as a negative electrode material of the negative electrode, the negative electrode can be suitably used as a power source of a watch for a long time.

When a control circuit for controlling the charging and discharging of the secondary battery is provided integrally with the secondary battery on the substrate of the solar battery, the thickness of the entire timepiece can be further reduced.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing a state in which a solar cell is provided with a combination of a secondary battery, a control circuit, and a timepiece movement in Embodiment 1 of the present invention.

FIG. 2 is a schematic explanatory view showing a state in which a secondary battery, a control circuit, and a timepiece movement are provided in combination in a solar battery in Embodiment 2 of the present invention.

FIG. 3 is a schematic explanatory view showing a state where a secondary battery, a control circuit, and a timepiece movement are provided in combination in a solar battery in Comparative Example 1.

FIG. 4 is a schematic explanatory view showing a state in which a solar cell, a secondary cell, and a control circuit are provided in combination in Embodiment 3 of the present invention.

FIG. 5 is a schematic explanatory view showing a state in which a solar cell, a secondary battery, and a control circuit are provided in combination in Comparative Example 2.

[Description of Signs] 10 Solar cell 11 Solar cell substrate 20 Secondary battery 21 Negative electrode 22 Solid electrolyte 23 Positive electrode 24 Positive electrode casing 30 Control circuit 40 Clock movement

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Toshiyuki Noma 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Inventor Koji Nishio 2-chome, Keihanhondori, Moriguchi-shi, Osaka No. 5-5 in Sanyo Electric Co., Ltd.

Claims (5)

[Claims] 1. A solar cell integrated secondary battery comprising a combination of a solar cell and a secondary battery, wherein a solar cell substrate having a conductive surface is used as an outer package of a positive electrode or a negative electrode in the secondary battery. A solar cell integrated type secondary battery characterized by the above-mentioned. 2. The solar cell integrated secondary battery according to claim 1, wherein the secondary battery is a solid electrolyte secondary battery. 3. The solar cell integrated secondary battery according to claim 1, wherein the negative electrode of the secondary battery is brought into contact with a substrate of the solar cell, and a metal oxide is used as a negative electrode material of the negative electrode. A watch characterized by the presence. 4. A timepiece using the solar cell integrated type secondary battery according to claim 1 as a power supply. 5. The timepiece according to claim 4, wherein a control circuit for controlling charging and discharging of the secondary battery is formed integrally with a substrate having a conductive surface of the solar cell. .