JP3531866B2 - Thin-film solid lithium ion secondary battery - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated thin-film solid lithium ion secondary battery in which two or more thin-film solid secondary battery cells are laminated, and a thin-film solid secondary battery cell and a silicon solar battery are laminated to form a composite. The present invention relates to a composite type thin film solid lithium ion secondary battery.

[0002]

2. Description of the Related Art Conventionally, as a positive electrode material of a lithium ion secondary battery, Li capable of inserting and extracting lithium ions has been used.
CoO ₂ , LiNiO ₂ , LiMn ₂ O ₂ , LiMnO
₂ , a lithium transition metal compound represented by LiM1 _x M2 _y O _z (M1 and M2 are transition metals, and x, y, and z are arbitrary real numbers) is used.

Further, as the negative electrode material, graphite capable of inserting and extracting lithium ions, carbon material such as coke, polymer burned material, metallic lithium, alloy of lithium and other metal, TiO ₂ , Nb ₂ O. ₅ , SnO ₂ , Fe ₂ O ₃ ,
A metal oxide such as SiO ₂ or a metal sulfide is used.

As the solid electrolyte, LiPF ₆ , LiCl in a polymer material such as polyethylene oxide, polypropylene oxide or polyethylene oxide derivative is used.
One containing a solute composed of a lithium salt such as O ₄ , gel-like one impregnated with a non-aqueous electrolytic solution obtained by dissolving this solute in an organic solvent, Li ₂ S, Li ₃ PO ₄ -N, etc. Inorganic solid electrolytes are known.

Recently, there has been great interest in and reported research on solid lithium secondary batteries and secondary batteries that do not use lithium metal. It is known that such a rocking chair type secondary battery is composed only of a thin film electrode having a semiconductor substrate as a support substrate and a solid electrolyte (Japanese Patent Laid-Open No. 10-
No. 284130).

Further, in such a secondary battery integrated with a solar cell in which a rocking chair type solid electrolyte secondary battery and a solar cell are combined facing each other, a plurality of thin film solar cell elements are connected in series to form a solar cell. A photoelectric conversion device suitable for installation on a rooftop of a house, in which a large number of solid thin film secondary batteries connected in series on the same substrate as the module are connected in parallel and the terminals are exposed to the outside and integrally sealed (Japanese Patent Laid-Open No. 8-33.
No. 0616 gazette) or a back electrode of a solar cell having a conductive surface is commonly used as an outer casing of a positive electrode or a negative electrode in a secondary battery, and a secondary battery suitable for a watch or the like having a thin battery thickness is known (special feature). Kaihei 11-74002).

The inventor of the present invention firstly prepared a niobium pentoxide film as a positive electrode active material on a metal substrate or a silicon substrate in a secondary battery using an alkali metal or an alkali metal alloy for the negative electrode and a solid electrolyte for the electrolyte. It has been found that by using a highly oriented thin film or a highly oriented thin film in which a niobium pentoxide film has been lithiated in advance, the battery can be made thinner and downsized, and the charge / discharge capacity is increased, and excellent charge / discharge characteristics are exhibited. (Japanese Patent Laid-Open No. 7-142054). Also,
V ₂ O ₅ , Nb ₂ O ₅ , WO containing lithium in advance
_{By using 3} , or MoO ₃ as the negative electrode active material,
It has been found that the battery can be made thinner and lighter, and the charge and discharge characteristics are excellent (JP-A-8-241707).

Furthermore, V2O5 is used for both the positive and negative electrodes.
We have developed and reported an all-solid-state lithium-ion secondary battery using (Electrochemical and Solid-State Letters, 2 (7) 3
20-322, 1999). This secondary battery has an open terminal voltage of 3.5-
It has a discharge capacity of about 6 μAh / cm ² when discharged to 1.0 V at 3.6 V and 10 μAh / cm ² . Also,
It showed relatively good cycle characteristics of 350 cycles or more and 0.079 V / month and self-discharge performance.

[0009]

It is compact, has high reliability, and therefore can be used for a lighter weight thin film solid state secondary battery which is widely used in various types of portable electronic devices and a charging operation. The development of a practical, all-solid-state, thin-film solid state secondary battery that is maintenance-free and has a high capacity is an issue.

[0010]

Means for Solving the Problems The present inventor has paid attention to the excellent characteristics of an all-solid-state lithium-ion secondary battery using V ₂ O ₅ for a positive electrode and a negative electrode, and has developed this to develop a laminated all-solid-state battery. In addition to developing a lithium-ion secondary battery, a maintenance-free, high-capacity practical all-solid-state solar cell composite thin-film solid lithium-ion secondary battery by combining an all-solid-state lithium-ion secondary battery and a silicon solar cell succeeded in.

That is, according to the present invention, (1) in a secondary battery in which two or more layers of thin-film all- solid-state lithium-ion secondary battery cells are stacked, the combination of the positive electrode active material and the negative electrode active material is L
i _x Mn ₂ O ₄ (1 ≦ x ≦ 2) / V ₂ O ₅ , V ₂ O ₅ /
Li _x V ₂ O ₅ (0 ≦ x ≦ 4), LiCoO ₂ / V ₂ O
_5, is either LiNiO ₂ / V ₂ O _5, solids collector
The resolution is expressed by the formula Li ₃ PO _4-y N _y (where 0 <y <0.
5) Nitrogen-containing lithium phosphate represented by 5)
The material of at least one electrode film is vanadium metal.
Yes, the upper layer cell is laminated in an inverted layered type in which the lower layer cell is inverted, and a single conductive layer is used as a common electrode film of the adjacent upper layer cell and lower layer cell so that the upper layer is either positive or negative. A laminated thin-film all- solid-state lithium ion secondary battery, characterized in that a terminal is provided on the common electrode film by interposing it between a cell and a lower layer cell.

The present invention also provides (2) the secondary of (1) above.
In the battery, the lowermost thin film solid lithium ion secondary battery cell is formed on the electrode film A formed on the surface of the substrate,
The thin film solid-state lithium ion secondary battery cell of the uppermost layer has an electrode film B formed on the surface, and has a polarity opposite to that of the common electrode film.
A terminal provided on the electrode film A and a terminal provided on the electrode film B
To connect in series, parallel, or series-parallel connection type laminated battery
This is a laminated thin film solid lithium ion secondary battery characterized by the above.

The present invention also provides (3) the secondary of (1) above.
In a battery, multiple common electrode films with different polarities
Cells are stacked so that
The lithium ion secondary battery cell is an electrode formed on the substrate surface
A thin film solid lithium ion layer formed on the film A and serving as the uppermost layer.
The secondary battery cell has an electrode film B formed on the surface,
Terminals and electrodes provided on the electrode film A having a polarity opposite to that of the polar film
A terminal provided on the membrane B is connected to form a parallel connection type laminated battery.
It is a laminated thin film solid lithium ion secondary battery characterized by the above.

Further, according to the present invention, (4) an insulating film is provided between respective electrode films which are common electrode films of the upper layer cell and the lower layer cell.
The laminated thin film solid lithium ion secondary battery according to the above (2) or (3) is characterized in that the cells are laminated as an interlayer insulating layer between the cells .

The present invention also provides (5) thin film solid lithium
The surface of the ion secondary battery cell layer exposed to the atmosphere is silicon nitride.
(1) characterized in that it is insulation-coated with a system film
To (4) the thin film solid lithium ion secondary battery
It is a pond.

[0016]

[0017]

The present invention also provides Li _x in which ( 6 ) Li ions are inserted into V ₂ O ₅ by a wet method or a dry method.
V ₂ O ₅ (0 ≦ x ≦ 4) is used as a negative electrode active material. The thin film solid lithium ion secondary battery according to any one of the above (1) to ( 5 ).

Further, according to the present invention, a thin film solid lithium ion secondary battery cell is laminated and compounded on a silicon solar battery formed on a transparent substrate with an insulating layer interposed therebetween, or a thin film solid formed on the substrate is used. A thin film solid-state lithium-ion secondary battery of the solar cell composite type, wherein a silicon solar battery is laminated on a lithium-ion secondary battery cell via an insulating layer to be composited.

Further, according to the present invention, a thin film solid lithium ion secondary battery cell and a silicon solar battery are separately formed on one substrate or on separate substrates and are combined to form a composite solar battery. It is a thin film solid lithium ion secondary battery.

Further, the present invention is the above-mentioned solar cell composite thin film solid lithium ion secondary battery, wherein the thin film solid lithium ion secondary battery cell is the above-mentioned laminated thin film solid lithium ion secondary battery. is there.

Further, according to the present invention, the surface of the thin film solid lithium ion secondary battery cell layer exposed to the atmosphere is insulation-coated with a silicon nitride based film. It is a battery or a solar cell composite type thin film solid lithium ion secondary battery.

In the case of solar cells, the series-connected solar cells described in the above-mentioned prior art cannot be stacked in the first place because of the operating principle. Therefore, they are laid on the same substrate and connected in series, or secondary batteries are connected in series. In the above example also, they are laid side by side on the same substrate and wired in series. These do not lead to the idea of stacking because the solid thin film secondary battery is not actually operated.

The present invention provides a single conductive layer with an adjacent top layer.
Either positive or negative as a common electrode film for the cell and the lower cell
By interposing between the upper layer cell and the lower layer cell so as to have the polarities described above and stacking them, thin film solid state secondary battery cells can be stacked, and thus a practical solar cell composite type thin film solid lithium ion A secondary battery could be obtained.
Thus, the upper cell and a lower layer adjacent the single conductive layer
By using it as a common electrode film with the cell , the manufacturing process can be simplified.

Further, the laminated lithium-ion secondary battery and the lithium-ion secondary battery in which the laminated lithium-ion secondary battery is combined with a solar cell are manufactured by applying silicon nitride as an insulating protective film and laminated thin film cells. It was possible to commercialize it for the first time by establishing a lithium insertion technology. The insulating protective film may be a film having protective properties such as electric conductivity and oxidation resistance for both electron conduction and ionic conduction, a reduction resistant atmosphere, and water resistance. It was found that the SiO ₂ film is defective, whereas the silicon nitride film exhibits good characteristics.

The thin film solid state secondary battery cell of the present invention comprises:
The combination of the positive electrode active material and the negative electrode active material is Li _x Mn ₂ O ₄
(1 ≦ x ≦ 2) / V 2 O 5, V 2 O 5 / Li x V 2 O 5
, LiCoO ₂ / V ₂ O ₅ , LiNiO ₂ / V ₂ O ₅
It is preferable that either of Further, as the solid electrolyte, a nitrogen-containing lithium phosphate salt represented by the formula Li ₃ PO _4-y N _y is preferable. When Li ₃ PO _4-y N _y is used, the ionic conductivity can be particularly increased by adding nitrogen.

The thin film solid lithium ion secondary battery consisting of all oxides and nitrides has good compatibility with air and is stable. V ₂ O ₅ / Li ₃ PO _4-y N _y / Li _x V ₂ O ₅
Has advantages such as a simple manufacturing process because the positive and negative electrode materials are the same. However, although weak against moisture, the silicon nitride-based film is most suitable as a protective insulating film that protects Li ions from being desorbed.

The thin film solid state secondary battery cell used in the present invention is
(1) Solid (electron) because the element structure is solid
High reliability and long life peculiar to the element, etc. can be expected, (2) Since it is a thin film, it is possible to stack and realize ultra-compact and lightweight, (3) It is a lithium ion cell that does not use metallic lithium To be highly safe,
(4) Since lithium is the most electrochemically base metal, it has a high energy density. (5) Since it is a secondary battery, it can be used repeatedly, and in principle, the same material can be used for a long time. It can be used and can contribute to resource saving.

The effective areas of the thin film solid lithium ion secondary battery and the solar cell are greatly different, and the features and merits of the solar cell composite lithium ion secondary battery are realized only when the laminated thin film lithium ion secondary battery is realized. On the contrary, the laminated lithium ion secondary battery is indispensable for making the solar cell composite type lithium ion secondary battery practical.

The effective area of the thin film solid secondary battery that can be charged by the solar cell is determined only by the area of the solar cell charging unit. That is, by stacking the thin film solid state secondary batteries, all of them are contained in the lower layer within the area of the solar cell.

The lithium-ion secondary battery in which the laminated lithium-ion secondary battery of the present invention is combined with a solar cell can simplify the charge control circuit, and can be used in the initial high-current high-speed charging process and in the latter stage. It has excellent advantages such as small current low speed charging process, automatic control of charging end potential and automatic stop function.

[0032]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG . 1 is an embodiment showing a laminated thin film solid lithium ion secondary battery of the present invention in the case of a two-layer cell. FIG. 1 shows a parallel connection type. The single cell 10 includes a positive electrode active material 1, a solid electrolyte 2, and a negative electrode active material 3. The cell 10 is laminated on the electrode film A 5 formed in layers on the surface of the substrate 4. A cell 20 having the same structure as the cell 10 is stacked on the cell 10.
Between the cell 10 and the cell 20, which is formed in a layer cell
The common electrode film 6 of 10 and the cell 20 is interposed. The uppermost cell 20 has an electrode film B 7 formed in layers on the surface.

In FIG. 1, the positive electrode terminal 8 is provided on the electrode film A 5 on the surface of the substrate 4, the positive electrode terminal 8 is provided on the electrode film B 7 on the surface of the upper cell 20, and the negative electrode terminal 9 is provided on the common electrode film 6. Is provided. In the case of the parallel type two-layer cell, as shown in FIG. 1, it is possible to use an inversion stacking type in which the upper layer cell 20 and the lower layer cell 10 are inverted. In this case, an insulating layer in a general multi-layer cell is not necessary. The manufacturing process is simplified.

The materials of the electrode film A 5, the common electrode film 6 and the electrode film B 7 are Mo, Ni and C which are usually used as electrode materials.
Any conductive material such as r, Al, Cu, Au may be used, but vanadium metal V is more preferable. This is because when V ₂ O ₅ is used as the positive electrode active material and / or the negative electrode active material, the same vanadium metal target is used when forming the V and V ₂ O ₅ films in the secondary battery manufacturing process. When the sputtering gas is pure Ar, a V metal film is formed, and when the Ar—O mixed gas is used, a V ₂ O ₅ film is formed, so that the manufacturing process of the secondary battery is simplified. And the interface characteristics between the V and V ₂ O ₅ films are physically and electrically preferable.

A wide variety of substrates can be used, such as a hard substrate such as a Si substrate or a glass substrate, a flexible metal thin plate, a plastic thin plate, or a polyethylene film substrate.

FIG. 2 shows an embodiment of a cell in which the laminated thin film solid lithium ion secondary battery of the present invention is laminated in multiple layers. FIG. 2 shows a common electrode type multilayer laminated cell (inverted laminated type parallel connection / same series parallel connection). They are connected by an external connection and do not use an insulating layer for multilayer stacking.

The insulating layer multilayer laminated cell of Figure 3, shown in Figure 2
In addition to the manufacturing process of the multi-layered cells, the process of providing the interlayer insulating layer 12 between the cells is added, which is the most general form, and is connected in series and parallel or series-parallel with external connection (coexistence). Can be selected, or can be connected in advance in a predetermined series / parallel / serial parallel.

The external connection type insulation layer type multi-layer laminated cells shown in FIG. 3 are connected in parallel at the time of charging to be charged by the solar battery of a single charger unit, and reconnected in series or series-parallel at the time of operation of the secondary battery. Can be used. Details will be described later.

FIG . 4 shows charge / discharge curves of the parallel type two-layer laminated thin film solid lithium ion secondary battery shown in FIG. Double the current of a single layer cell (current density is
It can be seen that it operates at 2.0 [μA / cm ² ].

FIG. 5 shows a mode in which the whole single-layer thin film solid lithium ion secondary battery formed on a substrate is covered with an insulating protective film 18 in order to investigate the characteristics of the insulating protective film. The thin-film solid lithium ion secondary battery 10 formed on the surface of the substrate 4 is covered with an insulating protective film 18 together with the positive electrode 5, the negative electrode 7, the terminal 8 and the terminal 9. The insulating protective film must retain the property of protecting the cell from the atmosphere, various gas atmospheres that are touched in daily life, and moisture.
At the same time, it is necessary to have a characteristic that does not lead to deterioration of battery operation by irreversibly taking in Li ⁺ ions.

Silicon nitride materials such as Si ₃ N ₄ and SiN are particularly suitable for the protective film of the thin film solid secondary battery cell used in the present invention. The silicon nitride film such as Si ₃ N ₄ or SiN can be formed by the RF AC sputtering method like other films. The film thickness is about 500 to 1500Å, preferably about 1000Å.

[0042] Figure 6 (a) shows a charge-discharge characteristic before the protective film deposition. 6 (b) shows the charge-discharge characteristics after Si ₃ N ₄ protective film deposition. Figure 6 (c) shows a charge-discharge characteristics after SiO ₂ protective film deposition. The charge / discharge characteristics (a) before film formation are
The characteristics are retained after the formation of the Si ₃ N ₄ protective film in (b), whereas the characteristics are retained after the formation of the SiO ₂ film in (c) in terms of both battery capacity and repetitive characteristics. The characteristics are significantly degraded. In the case of SiO ₂ , it has been proved that it is an excellent insulator electronically, but is insufficient for ions, as has been proved by Si-LSI.

Next, a suitable positive electrode active material used in the laminated lithium ion secondary battery of the present invention will be described.
When the positive electrode active material is a LiMn ₂ O ₄ battery, the positive electrode active material itself has Li ions as constituent atoms, and a part of it can be injected and poured out, but V ₂ O ₅ is used as the positive electrode active material. In the case of the V ₂ O ₅ / Li _x V ₂ O ₅ battery to be used, it is necessary to first insert Li ⁺ ions into V ₂ O ₅ (to make Li). ₂ O ₅ is the negative electrode V, the potential decreases when Li ⁺ ions are implanted, the resulting positive electrode V ₂ O ₅ and a negative electrode Li _x V
_A potential difference is generated between ₂ O ₅ and the Li ⁺ ions are exchanged thereafter, so that charge and discharge are performed. This type of secondary battery is called a rocking chair type.

As a method of first inserting Li ⁺ ions into V ₂ O ₅ (converting to Li), there are (1) wet type, (2) dry type, and (3) sputtering method. (3) In the sputtering method, Li is doped by co-sputtering in which V ₂ O ₅ and a Li-containing oxide are simultaneously sputtered from a _binary sputtering target when the V ₂ O ₅ film is formed.

FIG. 7 shows that L was added to V ₂ O ₅ using the wet method.
It is a fragmentary sectional view explaining the electrochemical method of the embodiment which inserts i ^<+> ion. The lithium-ion secondary battery cell 10 during or after fabrication is treated with a liquid electrolyte (1 mol of Li
In a solution obtained by dissolving ClO ₄ in a propylene carbonate solution), V ₂ O ₅ 3 to be a negative electrode is used as a positive electrode and a Li metal electrode is used as a negative electrode (not shown) to discharge Li.
^This is a method of inserting ⁺ ions into V ₂ O ₅ . in this case,
V ₂ O _{5, which} is the positive electrode, is left open.

[0046] There are three in the wet method, as shown in FIG. 7 (a)
Represents a direct type, is a method carried out before attaching the negative electrode (V) film of the uppermost layer portion has the disadvantage that Li _x V ₂ O ₅ -V interface is exposed once the solution.

[0047] FIG. 7 (b) shows an edge type, after completing a solid electrolyte thin film cell 10, small negative electrode film 7 (e.g., a metal V) slightly V ₂ O ₅ film not covered by Three
Is a method in which Li ⁺ ions are inserted from the periphery (edge portion) of the electrode and are circulated to the back surface covered with the electrode film 7 by lateral diffusion, so that Li _x V ₂ O ₅ −
While the V interface is not exposed to the solution, it is effective in the case of a small area cell in which lateral diffusion of Li ⁺ ions can sufficiently occur.

FIG. 7C shows a mesh type, and FIG.
This is to solve the defect of the edge type, in which the negative electrode film 7 is a mesh-shaped electrode film. By this method, sufficient Li insertion can be realized even in a large area cell.

The drying method shown in Figure 8, utilizes ion implantation is used in Si lithography art (ion implantation), a direct-type or mask-type in FIG. 8 (a), implanted in vacuum In the device, the V ₂ O ₅ film 3 in the upper layer is directly connected to the V ₂ O ₅ film 3 or through a mask.
Implant i ⁺ ions.

At this time, it is necessary to adjust the accelerating voltage so that the penetration depth of Li ⁺ ions does not penetrate into the lower solid electrolyte 2 and falls within the V ₂ O ₅ film 3.
Even if it is contained in the V ₂ O ₅ film 3, if the energy of Li ⁺ ions is too large, it forms a bond in the V ₂ O ₅ crystal to stabilize and become immovable, which cannot contribute to the battery operation. Therefore, it is necessary to set the Li ⁺ ion implantation acceleration voltage to a low voltage. Generally, when the accelerating voltage decreases, the ion current also decreases. The implantation time tends to be long.

In the indirect type (buffer type) of FIG. 8B , Li ⁺ ions are implanted into the lower V ₂ O ₅ film 3 through the thin film of the negative electrode film 7 (for example, metal V).
Li + ions are advantageous to the battery operation are lower movable Li ⁺ ion energy when entering the the appropriately decelerated in the V ₂ O ₅ film 3 (buffer) V ₂ O ₅ film 3.

FIG. 9 shows the results of monitoring changes in the negative electrode and positive electrode potentials when Li ions were inserted by the wet method. It was confirmed that the potential of V ₂ O ₅ expected to be the negative electrode was changed from about 3V to 0 potential, while the potential of V ₂ O ₅ expected to be the positive electrode was not changed at about 3V.

FIG. 10 shows the charge / discharge characteristics of the thin film solid lithium ion secondary battery of the present invention produced by inserting Li ions into V ₂ O ₅ by the wet method. Good charge / discharge characteristics are shown in FIG. It turns out that

FIG. 11 shows three types of the solar cell composite type thin film solid lithium ion secondary battery of the present invention. Figure 1
1 (a) is a secondary battery-on-solar battery type, in which a thin film solid secondary battery cell 10 is laminated on a Si solar battery 15 formed on the surface of a transparent substrate 14 via an insulating layer 16.
The silicon nitride film 11 is insulation-coated.
FIG. 11 (b), solar cells - a secondary battery type, - one
Thin film solid secondary battery cell 10 formed on the surface of substrate 4
The Si solar cell 15 is laminated on the insulating layer 16 and covered with the transparent protective film 17.

FIG. 11 (c) shows a coplanar type or a separate independent type in one diagram, in which the thin film solid state secondary battery cell 10 and the Si solar cell 15 are one substrate or a separated substrate 4. Alternatively, the thin-film solid state secondary battery cells 10 are separately formed on the transparent substrate 14, and are covered with the silicon nitride film 11 for insulation protection. The Si solar cell 15 is made according to whether the substrates 4 and 14 are transparent or opaque. And is covered with the silicon nitride film 11 or the transparent protective film 17.

11 (a), (b), and (c), only the unit cell 10 is shown as a thin film solid state secondary battery cell, but the thin film solid state secondary battery cell should be a multi-layer laminated cell. Thus, the effective cell areas of both the solar battery cell and the thin film solid secondary battery cell can be reduced. In this case, instead of the unit cell 10, the common electrode multilayer stack cell (inverted stacked parallel connection / the series-parallel connection) shown in FIG. 2,
And the insulating layer type multi-layer laminated cell shown in FIG. 3 (series / parallel /
One of the stacked thin film solid state secondary battery cells (serial / parallel connection) is used.

The electromotive force of a Si solar cell is about 0.65 V in a commercially available unit cell (single cell), and the photocurrent is about 70 μA / cm ² in a normal ceiling lamp (fluorescent lamp). It is about 100 μA / cm ² at the lamp stand. Under outdoor sunlight, it is more effective in terms of intensity and spectrum, and has a large photocurrent.

To charge a solid electrolyte thin film lithium ion secondary battery with a solar cell, three solar cells are connected in series for 2V charging and six for 4V charging (hereinafter referred to as "solar battery charger unit"). ")) Must be used. In the case of solar cells, even if they are connected in series, individual single cells need to be laid out in a plane and arranged. This is because every cell needs light. That is,
It takes a plurality of solar cells to charge one thin film solid state secondary battery cell.

12 and 13 show LiMn.
₂ O ₄ / Li ₃ PO _4-y N _y / V ₂ O ₅ solid electrolyte battery (effective area 100 mm ² ) is the effective area of the solar cell when it is charged by the solar battery charger unit consisting of 6 series cells. 6 is a graph showing charge characteristics and discharge characteristics as parameters. In the figure, the solar cell single cell area and the solar cell charger unit effective area are
(1) is 100 mm ² , 600 mm ² , (2) is 50 m
m ² , 300 mm ² , (3) is 17 mm ² , 100 mm
^{Is 2} .

Figure12(A) shows the relationship between charging time and charging current.
Graph showing the engagement,12(B) is charging time and terminal voltage
It is a graph which shows the relationship of. The charging end time is12
(A) charging current x charging time integrated area, that is, charging
It was decided that the amount would be constant. Also, the figureThirteen(A)
Discharge current of 5μA / cm²When fixed to
Figure shows the relationship between the discharge time and the terminal voltageThirteenIt shows in (b). end
The discharge was terminated when the child voltage reached 1.2V.

In the case of FIG. 12 (a) (charging current), the area of the solar cell is 100 → 50 → 17 mm under the room light.
^{When the value} is decreased to ² , in the embodiment, the total charging amount (the integrated value of the charging current) is kept constant, so that the charging time is increased. In this example, in the case of (3), that is, the area of the solar cell charging unit and the area of the secondary battery are about the same, but a charging time of about 40 minutes is required. However, (1),
(2), in any case of (3), of course, Figure 1
As seen in 3 , when the end voltage is 1.2V,
With a discharge current of 5 μA / cm ² , a discharge time of about 30 minutes (0.5 hr) was obtained, which is 2.5 μA / cm ² for this secondary battery.
It shows that it has a discharge capacity (or battery capacity) of cm ² .

Therefore, for example, when 10 rechargeable battery cells having the same area are stacked in parallel, the charging time is ten times as long as about 400 minutes (6.7 hours), but the same area as the solar battery charging unit (up to 100 mm). ² ) shows that a secondary battery pack having 10 times the battery capacity (25 μAh in this example) can be charged. Of course, if the irradiation intensity is increased, high speed charging can be performed in a shorter time. As described above, when the charge amount was kept constant (FIG. 12 (a)), in each of the cases (1), (2) and (3), the discharge time was about 30 minutes, which was expected. It showed good reproducibility.

When the irradiation (charging) condition is (1), the single cell of the solar cell has almost the same area as the solid lithium-ion secondary battery cell, but since there are 6 charger units in series, 600 mm ² , which requires an effective area of about 6 times that of a solid lithium ion secondary battery cell.

On the other hand, in the case of the condition (3), the single cell of the solar battery is 1/6 of the solid lithium ion secondary battery cell, but the occupied area as the charger unit is the solid lithium ion secondary battery. It will be similar to that of the cell. That is, at present, the areas of the solid lithium ion secondary battery cell and the charging solar battery (charger unit) are approximately the same. Although further improvement of the characteristics of the solid electrolyte battery can be expected, the improvement of the characteristics of the solar cell is saturated.

As has been made clear in the above embodiment, it was possible to charge the battery at a relatively high speed for about 40 minutes even under the condition (3). If the charging time is extended or the irradiation light intensity is increased, it is possible to charge a plurality of solid-state lithium-ion secondary battery cells at one time with one charger unit. By stacking the lithium-ion secondary battery cells in parallel, the battery capacity can be increased by the number of stacked batteries without increasing the effective area of the solid lithium-ion secondary battery cells. That is, it is possible to obtain the merit of charging by the solar cell by forming a composite with the solar cell only after stacking.

FIG. 14 shows a circuit configuration example of a solar cell composite type solid lithium ion secondary battery. The circuit of the solar cell composite type solid lithium ion secondary battery 30 of the present invention may have an extremely simple configuration of a diode D and a resistor R (a switch can be inserted if necessary). FIG. 14 shows an example in which the diode D and the resistor R are externally attached to individual elements (discrete elements). However, an all-thin film solar cell composite solid lithium ion secondary battery in which the diode and the resistor are made of thin films is used. You can also do it.

[0067] Figure 15 (a) shows the charge and discharge voltage of the solar cell composite solid-state lithium-ion secondary battery, and FIG. 15 (b)
Indicates the charge / discharge current. The measurement was performed under the lighting of a fluorescent lamp on the indoor ceiling, and the discharge characteristics used a commercially available digital stopwatch as a load. The load current decreases as the terminal voltage of the secondary battery decreases.

FIG. 16 is an enlarged view of one charging cycle shown in FIG. 15 (a). In this example, the charging current is about 12 μA at the beginning and then drastically decreases, and finally about 1 μA. Calm down. Along with this, the charging terminal voltage of the secondary battery also rises rapidly at first and then gradually increases from around 2.5V. If a resistance load is used instead of the secondary battery, a constant photocurrent flows under a constant irradiation intensity, and the voltage across the resistance also becomes constant. That is, as a result of combining the thin film lithium-ion secondary battery and the Si solar cell, it was newly found that the charging curve thereof draws an extremely ideal curve.

FIG. 17 shows the light intensity dependence of the charging characteristics of the solar cell composite type solid lithium ion secondary battery.
The Si solar cell was irradiated with light intensity due to room fluorescence through a dimming filter (shown in%). In the case of the present embodiment, even if the light intensity changes in the range of 50 to 15%, the balanced charging terminal voltage is within the range of 3.1 to 3.4V.

This data is obtained by designing the output voltage of the Si solar cell to the charging end voltage (full charge) of the lithium ion secondary battery in advance and automatically producing it without the need to check full charge. It means to end (self-stop function).

At the time of charging a commercially available lithium-ion secondary battery, since a liquid or polymer is used as the electrolyte,
It is necessary to take measures to prevent abnormalities such as disassembly and pressure rise due to overcharging.
The second half (on approaching full charge) uses special charge control electronics to prevent overcharging due to slow charging due to low current.

As described above, from the two data shown in FIGS. 16 and 17 , constant voltage / constant current charging circuit and its switching and full charge check function are required for charging the composite type lithium ion secondary battery of the present invention. It turns out that an extremely simple charging circuit does not suffice. A diode to block the reverse current from the secondary battery to the solar cell in the dark and an abnormally high photocurrent (during high irradiation), and to prevent a large current from flowing into the secondary battery due to a load short circuit. All you need is resistance.

[0073]

INDUSTRIAL APPLICABILITY Since the laminated solid electrolyte thin film lithium ion secondary battery of the present invention has elements laminated in series or in parallel, it can be used as a large voltage or large current power source in large power equipment such as electric vehicles. Is possible. Further, as an all-solid-state electrolyte thin-film solar secondary battery in which a laminated solid electrolyte thin-film lithium-ion secondary battery and a solar cell are combined, energy supply (charging) from a commercial power source is not required, so It has excellent characteristics such as maintenance-free semi-permanent power source characteristics and extremely simple charge control electronic circuit.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of a parallel- type two-layer laminated cell which is an embodiment of the laminated thin-film solid lithium ion secondary battery of the present invention.

FIG. 2 is a common electrode of a multilayer laminated cell which is an embodiment of a laminated thin film solid lithium ion secondary battery of the present invention.
It is a fragmentary sectional view of a type | mold .

FIG. 3 is a partial cross-sectional view of an insulating layer type of a multilayer laminated cell which is an embodiment of the laminated thin film solid lithium ion secondary battery of the present invention.

FIG. 4 is a graph showing a charge / discharge curve of the parallel type two-layer laminated thin film solid lithium ion secondary battery shown in FIG. 1.

FIG. 5 is a partial cross-sectional view showing an embodiment of a thin-film solid lithium ion secondary battery coated with an insulating protective film.

FIG. 6 shows a thin-film solid lithium-ion secondary battery with charge / discharge characteristics (a) before forming a protective film, charge / discharge characteristics (b) after forming a Si ₃ N ₄ protective film, and SiO ₂ protection. It is a graph which shows the charging / discharging characteristic (c) after film-forming.

FIG. 7 is a partial cross-sectional view illustrating an electrochemical method of an embodiment in which Li ⁺ ions are inserted into V ₂ O ₅ by using a wet method.

FIG. 8 is a partial cross-sectional view illustrating a direct type or a mask type (a) and an indirect (buffer) type (b) of an embodiment in which Li ions are inserted into V ₂ O ₅ by using a dry method. Is.

FIG. 9 is a graph showing changes in the negative electrode and positive electrode potentials when Li ions are inserted into V ₂ O ₅ using the wet method.

FIG. 10 is, Li a V ₂ O ₅ using a wet method
It is a graph which shows the charging / discharging characteristic of the thin film solid lithium ion secondary battery of this invention produced by inserting ions.

FIG. 11 shows an embodiment of a solar cell composite-type thin film solid lithium ion secondary battery of the present invention, in which a thin film solid secondary battery cell is laminated on a Si solar battery formed on a substrate (a). ), A thin-film solid secondary battery cell formed on a substrate and a Si solar cell laminated on the substrate (b), Si on the substrate
It is a partial cross-sectional view showing a coplanar type or a separate independent type (c) in which a solar cell and a thin film solid state secondary battery cell are separately formed.

FIG. 12 shows LiMn ₂ O ₄ / Li ₃ PO _4-y N _y.
/ V ₂ O ₅ and shows the charging characteristics and parameters of the effective area of the solar cell when the charge solid electrolyte batteries in series solar battery charger unit of six solar cells, FIG. 12 (a) is a graph showing the relationship between charging time and the charging current, Fig. 12 (b) is a graph showing the relationship between the charge time and the terminal voltage.

FIG. 13 shows LiMn ₂ O ₄ / Li ₃ PO _4-y N _y.
/ V ₂ O ₅ and shows the discharge characteristics of the effective area of the solar cell as a parameter of the solid electrolyte batteries in series solar battery charger unit of six solar cells when charging, Fig. 13 (a) is a graph showing the relationship between the discharge time and the charging current, Fig. 13 (b) is a graph showing the relationship between the discharge time and the terminal voltage.

FIG. 14 is a circuit diagram showing a control circuit of the solar cell composite type solid lithium ion secondary battery of the present invention.

FIG. 15 is a graph showing charge / discharge voltage (a) and charge / discharge current (b) of the solar cell composite type solid lithium ion secondary battery of the present invention.

16 is an enlarged graph of one charging cycle of the charging / discharging voltage shown in FIG. 15 (a).

FIG. 17 is a graph showing the light intensity dependence of the charging characteristics of the solar cell composite type solid lithium ion secondary battery of the present invention.

[Description of Reference Signs ] 1 positive electrode active material 2 solid electrolyte 3 negative electrode active material 4, 14 substrate 5 electrode film A 6 common electrode film 7 electrode film B 8 terminal 9 terminal 10, 20 thin film solid lithium ion secondary battery cell 11 silicon nitride Film 12 Interlayer insulating layer 15 Si solar cell 16 Insulating layer 17 Transparent protective film

Continuation of front page (51) Int.Cl. ⁷ Identification code FI H01M 4/02 H01M 4/02 CD 4/48 4/48 4/58 4/58 (56) Reference JP-A-11-260417 (JP , A) JP-A-11-111301 (JP, A) JP-A-10-208752 (JP, A) JP-A-9-102302 (JP, A) JP-A-11-260406 (JP, A) JP-A 58-126678 (JP, A) JP 60-72169 (JP, A) JP 8-241707 (JP, A) JP 7-122298 (JP, A) JP 3-155051 (JP, A) A) JP 7-312208 (JP, A) JP 2002-8726 (JP, A) JP 1-169973 (JP, A) JP 1-209673 (JP, A) JP 58- 216476 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01M 10/36-10/40 H01M 2/02-2/08 H01M 2/20-2/34 H01M 4/02 -4/04 H01M 4/38-4/62

Claims (6)

(57) [Claims] 1. A secondary battery comprising two or more layers of thin-film all- solid-state lithium-ion secondary battery cells laminated in a positive electrode active material and a negative electrode active material.
The combination of the polar active materials is Li _x Mn ₂ O ₄ (1 ≦ x ≦
2) / V ₂ O ₅ , V ₂ O ₅ / Li _x V ₂ O ₅ (0 ≦ x ≦
4), LiCoO ₂ / V ₂ O ₅ , LiNiO ₂ / V ₂ O
₅ and the solid electrolyte has the formula Li ₃ PO _4-y
Containing nitrogen represented by N _y (where 0 <y <0.5)
At least one electrode film of lithium phosphate
The material of is a vanadium metal, and the upper layer cell is laminated in an inverted layered type in which the lower layer cell is inverted, and a single conductive layer is used as a common electrode film of the adjacent upper layer cell and lower layer cell. The thin film all- solid-state lithium-ion secondary battery of the laminated type characterized in that a terminal is provided on the common electrode film by interposing it between the upper layer cell and the lower layer cell. 2. The secondary battery according to claim 1, wherein the lowermost thin film solid lithium ion secondary battery cell is formed on the electrode film A formed on the surface of the substrate, and the uppermost thin film solid lithium ion secondary battery is formed. The battery cell has an electrode film B formed on the surface.
The a, common electrode film and then connecting the terminals arranged on the terminal electrode films B formed in the electrode film A of opposite polarity, the stacked thin film all solid, characterized in that a parallel connection type laminated battery Lithium-ion secondary battery. 3. The secondary battery according to claim 1, wherein the cells are stacked so that a plurality of common electrode films have different polarities alternately, and the thin film solid lithium ion secondary battery cell at the bottom layer is a substrate surface. Formed on the electrode film A formed on
The thin-film solid lithium ion secondary battery cell of the uppermost layer has an electrode film B formed on the surface, and has a terminal provided on the electrode film A having a polarity opposite to that of the common electrode film and a terminal provided on the electrode film B. A laminated thin-film all- solid-state lithium-ion secondary battery, which is a connected, series, parallel, or series-parallel connected type laminated battery. 4. An insulating film is interposed as an inter-layer insulating layer between the respective cells, which is a common electrode film of the upper cell and the lower cell, and is laminated. 3. The laminated thin-film all- solid-state lithium-ion secondary battery described in 3. 5. The laminated thin film according to claim 1, wherein the surface of the thin film solid lithium-ion secondary battery cell layer exposed to the atmosphere is insulation-coated with a silicon nitride based film. All- solid-state lithium-ion secondary battery. 6. Li _x V ₂ O ₅ (0 ≦ x ≦ where Li ions are inserted into V ₂ O ₅ by a wet method or a dry method.
4. The thin film all- solid-state lithium ion secondary battery according to claim 1, wherein 4) is used as a negative electrode active material.