JP2002042863A - Thin-film solid-state lithium-ion secondary battery - Google Patents

Abstract

[PROBLEMS] To develop a lightweight, high-capacity, practical, all-solid-state laminated thin-film solid-state secondary battery and a composite thin-film solid-state secondary battery with a solar cell. The present invention provides a laminated thin-film solid lithium ion secondary battery comprising two or more thin-film solid lithium ion secondary battery cells. A single conductive layer is laminated as a common electrode film between the upper cell and the lower cell. Alternatively, lamination is performed with an insulating film interposed between the respective electrode films of the upper cell and the lower cell. Alternatively, the layers are stacked with the respective substrates of the upper cell and the lower cell interposed therebetween. Furthermore, a thin-film solid lithium-ion secondary battery cell is laminated on a silicon solar cell formed on a transparent substrate via an insulating layer, and the thin-film solid lithium-ion secondary battery cell formed on the substrate is combined. A solar cell composite thin-film solid lithium-ion secondary battery or a thin-film solid lithium-ion secondary battery cell and a silicon solar cell on a single substrate or on a separated substrate in which silicon solar cells are stacked and combined via an insulating layer Solar cell composite thin-film solid lithium-ion secondary battery formed separately and composited with a solar cell.

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-state lithium-ion secondary battery in which two or more thin-film solid-state secondary battery cells are laminated, and a composite of a thin-film solid-state secondary battery cell and a silicon solar battery by lamination. The present invention relates to a composite 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
CoO ₂ , LiNiO ₂ , LiMn ₂ O ₂ , LiMnO
_{2, LiM1 x M2 y O z} (M1, M2 is a transition metal, x, y, z are arbitrary real number) lithium transition metal compound is used represented by like.

Examples of the negative electrode material include graphite capable of absorbing and releasing lithium ions, carbon materials such as coke and polymer fired bodies, metallic lithium, alloys of lithium and other metals, TiO ₂ and Nb ₂ O. ₅ , SnO ₂ , Fe ₂ O ₃ ,
Metal oxides such as SiO ₂ and metal sulfides are used.

As a solid electrolyte, a polymer material such as polyethylene oxide, polypropylene oxide, or polyethylene oxide derivative contains LiPF ₆ , LiCl
A material containing a solute composed of a lithium salt such as O _4, a gel-like material impregnated with a non-aqueous electrolyte in which the solute is dissolved in an organic solvent, Li ₂ S, Li ₃ PO ₄ —N, etc. Are known.

[0005] Recently, there has been a great deal of interest in studies of solid lithium secondary batteries and secondary batteries that do not use lithium metal, which have been reported. It is known that such a rocking chair type secondary battery is composed of only a thin film electrode using a semiconductor substrate as a support substrate and a solid electrolyte (Japanese Patent Application Laid-Open No. 10-1998).
284130).

In a solar cell integrated type secondary battery in which such a rocking chair type solid electrolyte secondary battery and a solar cell are combined face to face, 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 house roof or the like, in which a large number of solid-state thin-film rechargeable 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.
No. 0616) and a secondary battery suitable for watches and the like, in which the thickness of the battery is reduced by using the back-facing electrode of a solar cell having a conductive surface in common as the outer package of the positive electrode or the negative electrode of the secondary battery. JP-A-11-74002).

The inventor of the present invention has previously made the negative electrode an alkali metal or the like.
Or an alkali metal alloy and a solid electrolyte
Rechargeable battery on a metal or silicon substrate
In addition, a highly oriented thin film of niobium pentoxide film as a cathode active material or
Is a highly oriented thin film obtained by preliminarily lithiating a niobium pentoxide film.
By using it, the battery can be made thinner and smaller,
Also increase the charge / discharge capacity and show excellent charge / discharge characteristics
(Japanese Unexamined Patent Publication (Kokai) No. 7-142054). Also,
V containing lithium in advance_TwoO_Five, Nb_TwoO _Five, WO
_Three, Or MoO_ThreeBy using as a negative electrode active material,
It is possible to make batteries thinner and lighter,
(JP-A-8-241707)
Gazette).

Furthermore, V is applied to both the positive and negative electrodes._TwoO_Five
Developed and reported an all-solid 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 to
3.6 V, 10 μAh / cm ^TwoAnd discharged to 1.0V
When about 6μAh / cm^TwoWith a discharge capacity of Also,
Relatively good over 350 cycles and 0.079V / month
It showed good cycle characteristics and self-discharge performance.

[0009]

SUMMARY OF THE INVENTION A compact and highly reliable thin-film solid-state secondary battery widely used in various forms of portable electronic devices, and a light-weight thin-film solid-state secondary battery. The development of a maintenance-free, high-capacity practical all-solid-state thin-film solid-state secondary battery that is unnecessary is an issue.

[0010]

The present inventors have focused on the excellent characteristics of an all solid lithium ion secondary battery using V ₂ O ₅ for the positive electrode and the negative electrode, In addition to developing lithium-ion secondary batteries, develop a maintenance-free, high-capacity practical all-solid-state solar cell composite thin-film solid-state lithium-ion secondary battery by combining all-solid-state lithium-ion secondary batteries and silicon solar cells succeeded in.

That is, the present invention is a stacked thin-film solid-state lithium-ion secondary battery characterized in that two or more thin-film solid-state lithium-ion secondary battery cells are stacked.

Further, the present invention provides a thin-film solid lithium ion secondary battery cell in which a single conductive layer is laminated as a common electrode film between an upper cell and a lower cell, and The ion secondary battery cell is formed on an electrode film formed on a substrate surface, and the uppermost thin-film solid lithium ion secondary battery cell has an electrode film formed on the surface. It is a laminated thin film solid lithium ion secondary battery.

Further, the present invention is the above-mentioned laminated thin-film solid lithium ion secondary battery, wherein the common electrode film is sandwiched between insulating layers.

Further, according to the present invention, a thin-film solid lithium ion secondary battery cell is laminated with an insulating film interposed between the respective electrode films of the upper cell and the lower cell, and the lowermost thin film solid lithium ion secondary battery is provided. The cell is formed on an electrode film formed on the substrate surface, and the thin film solid lithium ion secondary battery cell of the uppermost layer has an electrode film formed on the surface. It is a lithium ion secondary battery.

Further, according to the present invention, a thin-film solid lithium ion secondary battery cell is laminated with an upper cell and a lower cell interposed therebetween, and each thin-film solid lithium ion secondary battery cell is formed on the substrate surface. The laminated thin-film solid lithium-ion secondary battery described above, further comprising an electrode film formed on the electrode film and formed on the surface.

Further, according to the present invention, 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 (0 ≦ x ≦ 4), Li
CoO ₂ / V ₂ O ₅ , LiNiO ₂ / V ₂ O ₅ , and the solid electrolyte is a nitrogen-containing lithium phosphate salt represented by the formula Li ₃ PO _4-y N _y (where 0 <y <0.5). The stacked thin-film solid lithium ion secondary battery described above.

The present invention also provides the above-mentioned thin-film solid lithium ion secondary battery, wherein the material of at least one electrode film is vanadium metal.

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

Further, the present invention relates to a thin-film solid-state lithium ion secondary battery cell laminated on a silicon solar cell formed on a transparent substrate via an insulating layer, or a thin-film solid-state solid-state battery formed on a substrate. A solar cell composite type thin film solid lithium ion secondary battery characterized in that a silicon solar cell is laminated and combined with a lithium ion secondary battery cell via an insulating layer.

Further, the present invention provides a solar cell composite type wherein a thin-film solid lithium ion secondary battery cell and a silicon solar cell are separately formed on one substrate or separated substrates and then combined. It is a thin-film solid lithium ion secondary battery.

According to the present invention, there is further provided a solar cell composite-type 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.

The present invention also provides the above-mentioned laminated thin-film solid lithium ion secondary battery, wherein the surface of the thin-film solid lithium ion secondary battery cell layer exposed to the air is insulated and coated with a silicon nitride film. It is a battery or a solar cell composite thin film solid lithium ion secondary battery.

In the series-connected solar cells described in the above-mentioned prior art, since solar cells cannot be laminated in the first place because of the operating principle, they are laid out on the same substrate and arranged in series, or secondary cells are connected in series. Also in this example, they are laid out and wired in series on the same substrate. These have not led to the idea of lamination since the solid-state thin film secondary battery was not actually operated.

The present invention realizes lamination of a thin-film solid state secondary battery cell by laminating a single conductive layer as a common electrode film, thereby realizing a practical solar cell composite type thin-film solid state. A lithium ion secondary battery was obtained. As described above, by using a single conductive layer as the common electrode film, 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 formed by applying silicon nitride as an insulating protective film and laminating a thin film cell. For the first time, commercialization was possible by establishing a lithium insertion technology. The insulating protective film may be any film having a protective property such as electrical conductivity and oxidation resistance, reduction resistance atmosphere, and water resistance for both electron conduction and ion conduction. It has been found that the SiO ₂ film is defective, whereas the silicon nitride film exhibits good characteristics.

The thin-film solid secondary battery cell according to 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 to use any one of the following. As the solid electrolyte, a lithium phosphate salt containing nitrogen represented by the formula Li ₃ PO _4-y N _y is preferable. With _{Li 3 PO 4-y N y} , in particular it can increase the ionic conductivity by addition of nitrogen.

A thin-film solid lithium ion secondary battery composed entirely of 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 the advantage that the production process is simple because the positive and negative electrode materials are of the same type. However, it is weak to moisture,
A silicon nitride-based film is most suitable as a protective insulating film for protecting Li ions from being released.

The thin-film solid secondary battery cell used in the present invention comprises:
(1) Since the element structure is a solid, a solid (electron)
High reliability and long life can be expected, which are peculiar to devices, etc. (2) Ultra-small and light weight that can be laminated because it is a thin film. (3) Lithium ion cell that does not use lithium metal. High safety from
(4) Since lithium is the most electrochemically lowest metal, it has a high energy density. (5) Since it is a secondary battery, it can be used repeatedly. In principle, the same material can be used for a long time. It can be used and contributes to resource saving.

The effective areas of the thin-film solid lithium ion secondary battery and the solar cell are significantly different, and the characteristics and merits of the solar cell combined lithium-ion secondary battery are realized only after the realization of the laminated thin-film lithium-ion secondary battery. Conversely, a stacked lithium ion secondary battery is indispensable to make the solar cell composite lithium ion secondary battery practical.

The effective area of a thin-film solid state secondary battery that can be charged by a 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, they are all contained in the lower layer within the area of the solar cell.

The lithium-ion secondary battery obtained by combining the stacked lithium-ion secondary battery of the present invention with a solar cell can simplify the charge control circuit, and can perform the initial high-current high-speed charging process and the subsequent stage. It has excellent advantages such as small current low-speed charging process, automatic control of charging end potential and automatic stop function.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 and 2 show an embodiment in which a laminated thin-film solid lithium ion secondary battery of the present invention is a two-layer cell. FIG. 1 shows a series connection type,
FIG. 2 shows a parallel connection type. A 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 stacked on the electrode film 5 formed in a layer on the surface of the substrate 4. A cell 20 having the same structure as the cell 10 is stacked on the cell 10. The common electrode film 6 formed in a layer is interposed between the cell 10 and the cell 20. The surface of the uppermost cell 20 has the electrode film 7 formed in a layer shape.

In FIG. 1, the positive electrode terminal 8 is provided on the electrode film 5 on the surface of the substrate 4, and the negative electrode terminal 9 is provided on the electrode film 7 on the surface of the upper cell 20. In FIG. 2, the positive electrode terminal 8 is provided on the electrode film 5 on the surface of the substrate 4, the positive electrode terminal 8 is provided on the electrode film 7 on the surface of the upper cell 20, and the negative electrode terminal 9 is provided on the common electrode film 6. I have. In the case of a parallel type two-layer cell, as shown in FIG. 2, an inverted stacked type in which the upper cell 20 is inverted with respect to the lower cell 10 is possible. In this case, since an insulating layer in a general multilayer cell is not required, The manufacturing process is simplified.

The materials of the electrode films 5, 6, and 7 are as follows.
Mo, Ni, Cr, A usually used as an electrode material
Any conductive material such as 1, Cu, Au or the like may be used.
Indium metal V is more preferred. This is based on the cathode active material and
And / or V as an anode active material _TwoO_FiveWhen to use
In the secondary battery fabrication process, V and V_TwoO_FiveForm a film
When using the same vanadium metal target
If the sputtering gas is pure Ar, a V metal film is formed,
If an Ar-O mixed gas is used, V_TwoO_FiveThe film is deposited
Therefore, there is an advantage that the manufacturing process of the secondary battery is simplified.
And V and V_TwoO_FivePhysical and electrical characteristics of the interface with the film
Is also preferred.

As the substrate, 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. 3 is an embodiment showing a case where a multilayer thin-film solid-state lithium-ion secondary battery of the present invention is a multilayered cell. FIG. 3 (a1) shows a common electrode type multilayer laminated cell (series connection) cell. (A2)
1 shows a common electrode type multilayer stacked cell (inverted stacked type parallel connection / same series parallel connection). In each case, connection is made by external connection, and no insulating layer is used for multi-layer stacking. In the case of FIG. 3A2, the unit cells 10, 20,.
If the multilayer series cell of FIG. 3 (a1) is used instead of the unit cell in the portion indicated by, the cell becomes an inverted stacked series-parallel cell.
An insulating protective film 11 is provided on the uppermost n layer.

The insulating layer type multilayer cell shown in FIG. 3B is obtained by adding a step of providing an interlayer insulating layer 12 between the cells in addition to the manufacturing steps shown in FIGS. 3A1 and 3A2. This is the most general form, and it is possible to select serial and parallel or serial / parallel (coexistence) by external connection, or to connect in advance in a predetermined series / parallel / serial / parallel. FIG.
The separation / independent multi-stage stacked cell (series connection / parallel connection / serial / parallel connection) of (c) is intended for mass production, and the substrate 4 is a single-layer cell 10 of a roll-up type on a long base polymer film. Is manufactured and then cut to a fixed size and stacked in multiple stages. If necessary, it can be fixed (laminated) with an adhesive.

The external connection type insulating layer type multilayer laminated cell shown in FIG. 3 (b) is connected in parallel at the time of charging, and is charged by a solar cell of a single charger unit, and is operated in series or series-parallel at the time of operation of a secondary battery. It can be reconnected and used. Details will be described later.

FIGS. 4 and 5 show charge / discharge of the series-type two-layer laminated thin-film solid lithium ion secondary battery shown in FIG. 1 and the parallel-type two-layer laminated thin-film solid lithium ion secondary battery shown in FIG. 2, respectively. The curve is shown. In FIG. 4, it can be seen that the device operates at a high voltage which is about twice that of the single-layer cell. In FIG. 5, the current (current density is 2.0 [μA /
cm ² ]).

FIG. 6 shows an embodiment in which a single-layer thin-film solid lithium ion secondary battery formed on a substrate is covered with an insulating protective film 18 in order to examine the characteristics of the insulating protective film. The whole of the thin-film solid lithium ion secondary battery 10 formed on the surface of the substrate 4 together with the positive electrode 5, the negative electrode 7, the terminal 8, and the terminal 9 is covered with the insulating protective film 18. The insulating protective film must maintain the property of protecting the cell from the atmosphere, various gas atmospheres that are encountered in daily life, and moisture.
At the same time, it is necessary to have such characteristics that Li ⁺ ions are not irreversibly taken in and battery operation is not deteriorated.

As the protective film of the thin-film solid secondary battery cell used in the present invention, a silicon nitride-based material such as Si ₃ N ₄ or SiN is particularly suitable. The formation of a silicon nitride film such as Si ₃ N ₄ or SiN can be performed by the RF alternating current sputtering method like other films. The film thickness is about 500-1500 °, preferably about 1000 °.

[0042] FIG. 7A shows the charge / discharge characteristics before forming the protective film.
Is shown. FIG. 7 (b)_ThreeN _FourCharge / discharge after forming protective film
It shows the electrical characteristics. FIG. 7 (c)_TwoAfter forming the protective film
It shows charge and discharge characteristics. The charge / discharge characteristics (a) before film formation are as follows:
(B) Si_ThreeN_FourAfter forming the protective film, its characteristics are maintained
In contrast, (c) SiO_TwoAfter film formation
If the battery capacity and repetition characteristics are both large,
Has deteriorated. SiO _TwoIn the case of, demonstrated with Si-LSI
As already mentioned, it is an excellent insulator electronically,
Turned out to be insufficient.

Next, a preferred cathode active material used in the laminated lithium ion secondary battery of the present invention will be described.
If the positive electrode active material is LiMn ₂ O ₄ battery, the positive electrode active material itself has a Li ion as a constituent atom, a portion thereof infusion, although it is possible to dispense, the V ₂ O ₅ cathode active material In the case of a V ₂ O ₅ / Li _x V ₂ O ₅ battery, 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 with ₂ O _5, and charge and discharge are performed by exchanging the Li ⁺ ions thereafter. This type of secondary battery is called a rocking chair type.

First, Li⁺Ion to V_TwoO_FiveInsert into
(Li conversion) methods include (1) wet type, (2)
Lie type, (3) sputtering method. (3) Sputter method
Is V _TwoO_FiveBinary sputtering target during film formation
To V_TwoO_FiveAnd Li-containing oxides are simultaneously sputtered.
Li is doped by sputtering.

FIG. 8 shows that L is applied to V ₂ O ₅ using the wet method.
FIG. 4 is a partial cross-sectional view illustrating an electrochemical technique of an embodiment in which i ⁺ ions are inserted. The lithium ion secondary battery cell 10 during or after fabrication is replaced with a liquid electrolyte (1 mol Li
ClO ₄ among those dissolved in propylene carbonate solution), Li by discharging the V ₂ O ₅ 3 of the negative electrode will cathode, a Li metal electrode as a negative electrode (not shown)
^In this method, ⁺ ions are inserted into V ₂ O ₅ . in this case,
V ₂ O _{5, which} is a positive electrode, is left open.

There are three types of wet methods, as shown in FIG.
Shows a direct type, which is a method performed before the negative electrode (V) film on the uppermost layer is applied, but has a disadvantage that the Li _x V ₂ O ₅ -V interface is once exposed to a solution.

FIG. 8B shows an edge-type V ₂ O ₅ film which is not covered with a slightly smaller negative electrode film 7 (for example, metal V) after the solid electrolyte thin film cell 10 is completed. 3
Li ⁺ ions are inserted from the periphery (edge portion) of the substrate, and the Li ⁺ ions are wrapped around the back surface covered with the electrode film 7 by lateral diffusion to perform Li insertion, and Li _x V ₂ O ₅ −
Although the V interface is not exposed to the solution, it is effective in the case of a small area cell in which the lateral diffusion of Li ⁺ ions can sufficiently occur.

FIG. 8C shows a mesh type, and FIG.
In order to solve the disadvantage of the edge type, the negative electrode film 7 is a mesh-like electrode film. By this method, sufficient Li insertion can be realized even in a large area cell.

The dry method shown in FIG. 9 utilizes ion implantation (ion implantation) used in the field of Si lithography. The direct type or mask type shown in FIG. In the apparatus, L is directly applied to the upper layer V ₂ O ₅ film 3 or through a mask.
Implant i ⁺ ions.

At this time, Li⁺Ion penetration depth is lower
Without penetrating to the solid electrolyte 2, V _TwoO_FiveFit in membrane 3
It is necessary to adjust the accelerating voltage so that
Even if V_TwoO_FiveEven if it fits in the film 3, Li⁺Ion's
If the energy is too large, V_TwoO_FiveCreate bonds in the crystal
Stabilizes and becomes unable to move, contributing to battery operation
Can not. Therefore, Li⁺Ion implantation acceleration voltage
Must be set to a low voltage. Generally, acceleration voltage decreases
Then, the ion current becomes low. Driving time
Tends to be longer.

The indirect type (buffer) shown in FIG.
Type) passes through a thin film of the negative electrode film 7 (for example, metal V).
The lower V_TwoO_FiveLi for film 3⁺To implant ions,
Li ⁺Ion is V_TwoO_FiveIt is decelerated appropriately in the membrane 3 (batch
Fa) V_TwoO_FiveLow energy when entering the membrane 3
Movable Li⁺Ion, which is convenient for battery operation.
You.

FIG. 10 shows the results of monitoring changes in the negative electrode and positive electrode potentials during the insertion of Li ions by the wet method. It was confirmed that the potential of the planned negative electrode V ₂ O ₅ changed from about 3 V to 0 potential, while the potential of the planned positive electrode V ₂ O ₅ did not change at about 3 V.

FIG. 11 shows the charge / discharge characteristics of the thin-film solid lithium ion secondary battery of the present invention prepared by inserting Li ions into V ₂ O ₅ using the wet method. Is obtained.

FIG. 12 shows three types of solar cell composite type thin film solid lithium ion secondary batteries of the present invention. Figure 1
2 (a) is a secondary battery-on-solar battery type, in which a thin-film solid secondary battery cell 10 is laminated via an insulating layer 16 on a Si solar battery 15 formed on the surface of a transparent substrate 14,
It is formed by insulating protection coating with a silicon nitride film 11.
FIG. 12B shows a solar cell-on-secondary cell type,
Thin-film solid secondary battery cell 10 formed on the surface of substrate 4
A solar cell 15 is laminated via an insulating layer 16 and is covered with a transparent protective film 17.

FIG. 12 (c) shows the coplanar type or the separated independent type in one figure, in which the thin-film solid state secondary battery cell 10 and the Si solar cell 15 are one substrate or the separated substrate 4 Alternatively, the thin-film solid-state secondary battery cells 10 are separately formed on a transparent substrate 14, and are insulated and coated with a silicon nitride film 11, and the Si solar cell 15 is formed according to whether the substrates 4 and 14 are transparent or opaque. And is covered with a silicon nitride film 11 or a transparent protective film 17.

In FIGS. 12A, 12B and 12C, only the unit cell 10 is shown as a thin-film solid-state secondary battery cell. Thereby, the effective cell area of both the solar battery cell and the thin-film solid secondary battery cell can be reduced. In this case, in place of the unit cell 10, the common electrode type multilayer laminated cell (series connection) shown in FIG. 3A1 and the common electrode type multilayer laminated cell shown in FIG. One of the stacked thin-film solid-state secondary battery cells of the serial-parallel connection) and the insulating-layer-type multilayer stacked cell (series / parallel / series-parallel connection) shown in FIG. 3B is used.

The electromotive force of a Si solar cell is about 0.65 V for a commercially available unit cell (single cell), the photocurrent is about 70 μA / cm ^{2 for} a normal ceiling light (fluorescent lamp), It is about 100 μA / cm ² for a lamp stand. Under outdoor sunlight, the intensity and spectrum are more effective and the photocurrent is larger.

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

FIGS. 13 and 14 show LiMn, respectively.
₂ O ₄ / Li ₃ PO _4-y N _y / V ₂ O ₅ solid electrolyte battery (effective area 100 mm ² ) 7 is a graph showing charging characteristics and discharging characteristics using the effective area of a solar cell as a parameter when charging is performed by a solar cell charger unit including six series cells. In the figure, the solar cell single cell area and the effective area of the solar cell charger unit are respectively:
(1) is 100 mm ² , 600 mm ² , (2) is 50 m
m ² , 300 mm ² , (3) is 17 mm ² , 100 mm
²

FIG. 13A is a graph showing the relationship between the charging time and the charging current, and FIG. 13B is a graph showing the relationship between the charging time and the terminal voltage. The charging end time is shown in FIG.
The integral area of (charging current) × (charging time) in (a), that is, the charging amount was determined to be constant. FIG. 14 (a)
FIG. 14B shows the relationship between the discharge time and the terminal voltage when the discharge current is fixed at 5 μA / cm ² as shown in FIG. The discharge was terminated when the terminal voltage reached 1.2 V.

In the case of FIG. 13A (charging current), the area of the solar cell was changed from 100 → 50 → 17 mm under an indoor lamp.
^{When the value} is decreased to ² , the embodiment shows an increase in the charging time because the total charge amount (integrated value of the charging current) is kept constant. In this example, in the case of (3), that is, the area of the solar battery charging unit and the area of the secondary battery are almost the same, but a charging time of about 40 minutes is required. However, (1),
In either case of (2) or (3), FIG.
As seen in Fig. 4, when the end voltage is set to 1.2V,
At a discharge current of 5 μA / cm ² , a discharge time of about 30 minutes (0.5 hr) is obtained, which indicates that the secondary battery has a discharge current of ^2.5 μA / cm ^2.
It has a discharge capacity (or battery capacity) of cm ² .

Therefore, for example, when ten secondary battery cells of the same area are stacked in parallel, the charging time is ten times as long as about 400 minutes (6.7 hr), but the same area (up to 100 mm) as the solar battery charging unit. ² ) 10 times the battery capacity (in this example, 25 μAh) indicates that the secondary battery pack can be charged. Of course, if the irradiation intensity is increased, shorter-time high-speed charging is possible. Thus, when the charge amount was kept constant (FIG. 13 (a)), in each of the cases (1), (2) and (3), a discharge time approximately equal to about 30 minutes was given, which was expected. Good reproducibility was shown.

When the irradiation (charge) condition is (1), the single cell of the solar cell has substantially the same area as the solid lithium ion secondary battery cell. ² , which requires about six times the effective area of the solid lithium ion secondary battery cell.

On the other hand, when the condition is (3), the single cell of the solar cell is 1/6 of the solid lithium ion secondary battery cell, but the area occupied by the charger unit is as small as It is comparable to that of the cell. That is, at present, the solid lithium ion secondary battery cell and the charging solar cell (charger unit) have approximately the same area. Further improvement in the characteristics of the solid electrolyte battery can be expected, but the improvement in the characteristics of the solar cell is saturated.

As has been clarified in the above embodiment, a relatively high-speed charging of about 40 minutes was possible even in the case of 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 once with one charger unit. If the lithium ion secondary battery cells are stacked in parallel, the battery capacity can be increased by the number of stacked layers without increasing the effective area of the solid lithium ion secondary battery cells. That is, the merits of charging by the solar cell by combining with the solar cell can be obtained only after the lamination.

FIG. 15 shows an example of a circuit configuration of a solar cell composite type solid lithium ion secondary battery. The circuit of the solar cell combined solid lithium ion secondary battery 30 of the present invention may have a very simple configuration of a diode D and a resistor R (a switch can be inserted if necessary). FIG. 15 shows an example in which a diode D and a resistor R are externally provided as individual elements (discrete elements). You can also.

FIG. 16 (a) shows the charge / discharge voltage of the solar cell composite type solid lithium ion secondary battery, and FIG.
Indicates charge / discharge current. The measurement was performed under fluorescent lamp illumination on the indoor ceiling, and the discharge characteristics were measured using a commercially available digital stopwatch as a load. As the terminal voltage of the secondary battery decreases, the load current decreases.

FIG. 17 is an enlarged view of one charging cycle shown in FIG. 16 (a). In this example, the charging current is about 12 μA at first, then decreases rapidly, and finally reaches about 1 μA. Calm down. Along with this, the charging terminal voltage of the secondary battery also increases rapidly at first, and then gradually increases from around 2.5V. If a resistive load is used instead of the secondary battery, a constant photocurrent flows under a constant irradiation intensity, and the voltage across the resistor also becomes constant. That is, as a result of combining the thin-film lithium-ion secondary battery and the Si solar battery, it has been newly found that the charging curve draws an extremely ideal curve.

FIG. 18 shows the light intensity dependency of the charging characteristics of the solar cell composite type solid lithium ion secondary battery.
The light intensity of the room fluorescent light was applied to a Si solar cell through a dimming filter (indicated by%). 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 falls in the range of 3.1 to 3.4 V.

If the output voltage of the Si solar cell is designed and manufactured in advance to the charge end voltage (full charge) of the lithium ion secondary battery, this data is automatically obtained without checking the full charge. It means to end (self stop function).

At the time of charging a commercially available lithium ion secondary battery, a liquid or a polymer is used as an electrolyte.
It is necessary to take measures to prevent abnormalities such as decomposition and pressure rise due to overcharging.
In the second half (when nearing full charge), a special charge control electronic circuit is used so that overcharge is not exceeded by low-speed charge with low current.

As described above, based on the two data shown in FIGS. 17 and 18, when charging the composite lithium ion secondary battery of the present invention, a constant voltage / constant current charging circuit and its switching and full charge checking functions are required. It turns out that a very simple charging circuit is not required. A diode for preventing reverse current from the secondary battery to the solar cell in the dark and an extraordinarily high photocurrent (during high irradiation) and for suppressing a large current due to a load short circuit from flowing to the secondary battery All that is needed is the resistance.

[0073]

The stacked solid electrolyte thin film lithium ion secondary battery of the present invention has elements stacked in a series or parallel connection, so that it can be used as a large voltage or large current power supply for high power devices such as electric vehicles. Is possible. In addition, as an all-solid-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 supply is not required. It has the characteristics of a semi-permanent power supply free of maintenance (charging, etc.) and an extremely simple charge control electronic circuit.

[Brief description of the drawings]

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

FIG. 2 is a partial cross-sectional view of a parallel two-layer laminated cell which is one embodiment of the laminated thin-film solid lithium ion secondary battery of the present invention.

FIGS. 3A and 3B are common electrode types (a1) and (a2), an insulating layer type (b), and a separation type of a multilayer stacked cell as an embodiment of the stacked thin-film solid lithium ion secondary battery of the present invention. It is a fragmentary sectional view of (standalone type) (c).

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

FIG. 5 is a graph showing a charge / discharge curve of the parallel type two-layer stacked type thin film solid lithium ion secondary battery shown in FIG.

FIG. 6 is a partial cross-sectional view showing an embodiment of a thin-film solid lithium ion secondary battery covered with an insulating protective film.

FIG. 7 is a graph showing charge / discharge characteristics before forming a protective film (a), charge / discharge characteristics after forming a Si ₃ N ₄ protective film (b), and protection of SiO _{2 for} a thin-film solid lithium ion secondary battery. 4 is a graph showing charge / discharge characteristics (c) after film formation.

FIG. 8 shows that Li ⁺ is added to V ₂ O ₅ using a wet method.
FIG. 3 is a partial cross-sectional view illustrating an electrochemical method of an embodiment in which ions are inserted.

FIG. 9 is a partial cross-sectional view illustrating a direct type or mask type (a) and an indirect (buffer) type (b) of an embodiment in which Li ions are inserted into V ₂ O ₅ using a dry method. It is.

FIG. 10 is a graph showing the relationship between L and V ₂ O ₅ using a wet method;
It is a graph which shows the change of the negative electrode and positive electrode potential at the time of i ion insertion.

FIG. 11 is a graph showing the relationship between L and V ₂ O ₅ using a wet method;
4 is a graph showing charge / discharge characteristics of a thin-film solid lithium ion secondary battery of the present invention prepared by inserting i-ions.

FIG. 12 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 cell formed on a substrate (a). ), A thin-film solid-state secondary battery cell formed on a substrate, on which a Si solar cell is laminated (b);
FIG. 6 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 secondary battery cell are separately formed.

FIG. 13 shows LiMn ₂ O ₄ / Li ₃ PO _4-yN
FIG. 13 (a) shows the charging characteristics with the effective area of the solar cell as a parameter when the _y / V ₂ O ₅ solid electrolyte battery is charged by a series solar cell charger unit composed of six solar cells. ) Is a graph showing the relationship between the charging time and the charging current, and FIG. 13B is a graph showing the relationship between the charging time and the terminal voltage.

FIG. 14 shows LiMn ₂ O ₄ / Li ₃ PO _4-yN
FIG. 14 (a) shows a discharge characteristic using the effective area of a solar cell as a parameter when the _y / V ₂ O ₅ solid electrolyte battery is charged by a series solar cell charger unit including six solar cells. ) Is a graph showing the relationship between the discharge time and the charging current, and FIG. 14B is a graph showing the relationship between the discharge time and the terminal voltage.

FIG. 15 is a circuit diagram showing a control circuit of the solar cell combined type solid lithium ion secondary battery of the present invention.

FIG. 16 is a graph showing a charge / discharge voltage (a) and a charge / discharge current (b) of the solar cell combined type solid lithium ion secondary battery of the present invention.

FIG. 17 is an enlarged graph of one charge cycle of the charge / discharge voltage shown in FIG. 16 (a).

FIG. 18 is a graph showing the light intensity dependence of the charging characteristics of the combined solar battery solid-state lithium ion secondary battery of the present invention.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01M 4/02 H01M 4/48 5H050 4/48 4/58 4/58 10/36 A 10/36 10 / 46 10/46 H01L 31/04 K F term (reference) 5F051 JA07 JA17 5H011 AA00 AA02 AA04 AA05 AA06 AA07 AA09 AA13 AA17 CC05 DD21 5H022 AA09 AA19 CC25 EE01 EE03 EE04 EE07 KK04 A15 A02 A02 A02 BJ04 BJ06 BJ12 DJ01 DJ02 DJ04 DJ05 DJ11 EJ01 EJ03 EJ06 EJ12 HJ02 HJ12 5H030 AA09 AA10 AS00 AS08 BB07 DD01 DD09 DD20 DD30 5H050 AA00 AA01 AA15 AA18 AA19 AA20 BA15 CA02 CA08 CA09 CB02 FA01 DA02

Claims (12)

[Claims] 1. A stacked thin-film solid lithium ion secondary battery comprising two or more thin-film solid lithium ion secondary battery cells stacked. 2. A thin-film solid-state lithium-ion secondary battery in which a single conductive layer is interposed between an upper-layer cell and a lower-layer cell with a single conductive layer serving as a common electrode film. 2. The lamination according to claim 1, wherein the cell is formed on an electrode film formed on the substrate surface, and the uppermost thin film solid lithium ion secondary battery cell has the electrode film formed on the surface. Type thin film solid lithium ion secondary battery. 3. The laminated thin-film solid lithium ion secondary battery according to claim 2, wherein the common electrode film is sandwiched between insulating layers. 4. A thin-film solid lithium-ion secondary battery cell is stacked with an insulating film interposed between respective electrode films of an upper cell and a lower cell, and the lowermost thin-film solid lithium-ion secondary battery cell is mounted on a substrate surface. 2. The laminated thin-film solid lithium ion according to claim 1, wherein the thin-film solid lithium ion secondary battery cell formed on the electrode film formed on the uppermost layer has an electrode film formed on the surface. Ion secondary battery. 5. A thin-film solid lithium-ion secondary battery cell is stacked with an upper cell and a lower cell interposed therebetween, and each thin-film solid lithium-ion secondary battery cell is formed on an electrode film formed on the substrate surface. 2. The laminated thin-film solid lithium-ion secondary battery according to claim 1, further comprising an electrode film formed on the surface of the battery. 6. The combination of a positive electrode active material and a negative electrode active material
Li_xMn_TwoO_Four(1 ≦ x ≦ 2) / V_TwoO_Five, V_TwoO_Five
/ Li_xV_TwoO_Five(0 ≦ x ≦ 4), LiCoO _Two/ V_Two
O_Five, LiNiO_Two/ V_TwoO_FiveIs either a solid
The electrolyte is of the formula Li _ThreePO_4-yN_y(However, 0 <y <0.
It is a lithium phosphate salt containing nitrogen represented by 5)
The product according to any one of claims 1 to 5, wherein
Layered thin film solid lithium ion secondary battery. 7. The thin-film solid lithium ion secondary battery according to claim 1, wherein a material of at least one electrode film is vanadium metal. 8. Li _x V ₂ O _{5 wherein} Li ions are inserted into V ₂ O ₅ by a wet method or a dry method (0 ≦ x ≦
8. The thin-film solid lithium ion secondary battery according to claim 1, wherein 4) is used as a negative electrode active material. 9. A thin-film solid lithium-ion secondary battery cell laminated on a silicon solar cell formed on a transparent substrate via an insulating layer, or a thin-film solid lithium-ion secondary battery cell formed on a substrate. A solar cell composite type thin film solid lithium ion secondary battery, wherein a silicon solar cell is laminated on a battery cell via an insulating layer and composited. 10. A solar cell composite type thin film solid lithium ion, wherein a thin film solid lithium ion secondary battery cell and a silicon solar cell are separately formed on one substrate or a separated substrate and are combined. Rechargeable battery. 11. A thin-film solid lithium ion secondary battery according to claim 1, wherein the thin-film solid lithium ion secondary battery cell is a laminated thin-film solid lithium ion secondary battery.
Or a solar cell composite type thin film solid lithium ion secondary battery according to item 10. 12. The laminated thin film according to claim 1, wherein a surface of the thin film solid lithium ion secondary battery cell layer exposed to the air is insulated and coated with a silicon nitride-based film. A solid lithium ion secondary battery or a solar cell composite thin film solid lithium ion secondary battery.