JP3251978B2 - Composite electrode and 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 technical field of a sheet-shaped thin battery and a sheet-shaped thin battery using the same.

[0002]

2. Description of the Related Art In recent years, with the miniaturization, weight reduction, and handheldness of electric equipment, there has been an increasing demand for high energy density and miniaturization of batteries as power sources, and various batteries have been proposed. Above all, thin batteries are attracting attention as high-output, high-energy density, spaceless batteries. However, thin batteries are not enough in terms of energy capacity,
At present, it is limited to applications such as memory backup and power supplies for low power devices. Although it is possible to improve the energy capacity by increasing the area, it becomes more difficult to fix the sheet-like electrode to the current collector substrate as the area increases, and the peeling and peeling from the edge of the electrode become remarkable. Come. Therefore, sufficient current collection from the electrode cannot be performed, and the expected energy capacity cannot be obtained.
Also, when handling the battery, the sheet-like electrode begins to peel off from the end of the current collector substrate due to bending of the battery, etc.
After all, the energy capacity becomes small.

[0003]

An object of the present invention is to provide an electrode which has solved the above-mentioned problems, and a high-performance and highly reliable sheet-shaped thin battery using the electrode, which has a high energy capacity.

[0004]

According to a first aspect of the present invention, in a sheet-like electrode coated and fixed on a current collector substrate with a current collector substrate and a fusible film, the fusible film is a porous film; The present invention relates to a sheet-shaped electrode having an opening having a size and a shape capable of forming an overlapping portion with the sheet-shaped electrode at an outer peripheral edge of the sheet-shaped electrode. In the second aspect of the present invention, in the sheet-like electrode covered and fixed by the current collector substrate and the fusible film, the fusible film is formed at least at an outer peripheral edge of the sheet-like electrode. The present invention relates to a sheet-shaped electrode having an opening having a size and a shape capable of forming an overlapping portion with the sheet-shaped electrode, and having a large number of holes in the overlapping portion. Third of the present invention
In the sheet-like electrode covered and fixed by the current collector substrate and the fusible film, the fusible film is a porous film, and at least the outer peripheral edge of the sheet-like electrode. The present invention relates to a sheet-shaped electrode having an opening having a size and a shape capable of forming an overlapping portion with the sheet-shaped electrode, wherein a large number of holes are provided in the overlapping portion. A fourth aspect of the present invention relates to a sheet-shaped thin battery, wherein at least one of the two electrodes is constituted by the electrode according to any one of claims 1 to 3. The structure of the present invention will be specifically described with reference to FIGS. However, the battery of the present invention is not limited to those shown in these drawings. According to the present invention, when a large-area battery element, for example, a large-area sheet electrode having a size of 25 cm ² or more, particularly 50 cm ² or more, is fixed on a current collector substrate, the effect is enhanced.

In the present invention, as the fusible film, an opening (hole) having a size and shape capable of forming a portion overlapping the sheet electrode and at least the outer peripheral portion thereof is provided in the fusible film. Thus, the electrodes could be more firmly fixed on the current collector (FIG. 1). However, when the fusible film having the opening as described above is used, the sheet electrode is firmly fixed on the current collector substrate, but the sheet electrode overlaps with the fusible film. Almost no energy can be extracted. Therefore, the present inventors form a large number of holes in the film before or after fusion at a portion corresponding to the overlapping portion (FIG. 2), or use a porous film that can pass ions. As a result, the above problem was solved, and the reduction in the capacitance of the overlapping area could be minimized. The size of the hole formed in the fusible film is preferably about 0.5 to 10 mm. Also, the number of holes varies depending on the size,
About 00 / cm ² is preferable.

As another mode of fixing a sheet electrode to a current collector substrate using a film having a fusibility, instead of using a fusion film having openings as shown in FIGS. The sheet electrode can be fixed to the current collector substrate in the same manner as described above using a porous fusion film having no opening. In this case, when fusion is performed by heat, many of the pores are closed, so that a large number of holes are preferably formed in the portion of the fusion film that overlaps the sheet-like electrode as shown in FIG. Further, it is more preferable that the porous fusion film also serves as a separator. By employing such a configuration, an extremely thin electrode having high reliability can be obtained.

[0007] It is desired that the fusible film be fused with heat of 70 ° C to 200 ° C.
C. to 150C. If the film is fused at 70 ° C. or less, the film lacks stability and reliability. If the film does not fuse at 200 ° C. or more, it causes melting or deterioration of the sheet electrode active material. Examples of the fusible film include heat fusible films such as modified polyethylene and modified polypropylene.Especially, when the fusible film is also used as a separator, a polymer pore filter such as polyethylene and polypropylene is most preferable. preferable. The overlapping portion between the fusible film and the sheet electrode is preferably about 1 mm or more in order to fuse the two more firmly.

In the battery of the present invention, after a battery element and a partition which at least one of a positive electrode and a negative electrode are formed of the above-mentioned sheet electrode and an electrolyte are laminated, the partition and the current collector are bonded and sealed. It is manufactured by doing.

FIG. 4 shows an example of the sheet-like thin film battery of the present invention. Examples of the positive electrode (b) include a transition metal chalcogen compound and a conductive polymer compound, and examples of the transition metal chalcogen compound include TiO ₂ , Cr ₃ O ₈ , V ₂ O ₅ , and V ₃
Oxides such as O ₆ , NiO ₂ , MnO ₂ , CoO ₂ and MoO ₃ , sulfides such as TiS ₂ , VS ₂ , FeS and MoS ₃ and selenium compounds such as NbSe ₃ , V, M
Examples thereof include a sheet of a composite oxide of n, Co, Ni and an alkali metal. In addition, as the conductive high molecular compound, a sheet of polyacetylene, polyparaphenylene, polypyrrole, polythiophene, polyazulene, polydiphenylbenzidine, polyphthalocyanine, polyaniline, or the like can be used. Further, a sheet formed from a complex of a chalcogenide of a transition metal and a conductive polymer can also be used. Examples of the negative electrode active material constituting the negative electrode (i) include alkali metals such as Li, K, and Na, and Li and Al, Pb, Cd, Si, Ca, In,
Examples include alloys with Zn and Mg, polymer materials such as polyacetylene, polythiophene, polyparaphenylene, polypyridine, polyphenylenevinylene, polyphenylene xylylene, and reduced polymers of hexachlorobutadiene, carbon bodies, and graphite.

Examples of the electrolyte include an electrolytic solution comprising an electrolyte salt and a solvent, and a solid electrolyte. However, it is preferable to use a solid polymer electrolyte in order to prevent liquid leakage, maintain close contact between the positive and negative electrodes, and keep the distance constant. When an electrolytic solution is used, it is preferable that the separator contains the electrolytic solution. As an electrolyte salt of the electrolyte, PF is used as an anion.
₆ (−), SbF ₆ (−), AsF ₆ (−), SbCl
₆ A halide anion of a Va group element such as (−): a halide anion of a IIIa group element such as BF ₄ (−), BR ₄ (−) (R: phenyl group, alkyl group); ClO ₄ Perchlorate anion such as (-); Cl
Examples thereof include halogen anions such as (−), Br (−) and I (−), and CF ₃ SO ₃ (−). Examples of the cation include alkali metal ions such as Li (+), Na (+) and K (+), (R ₄ N) (+) [R: 1 to 20 carbon atoms.
A hydrocarbon group] and the like. [The above (+) and (-) represent a positive ion and a negative ion, respectively. The same applies hereinafter. Specific examples of the above-mentioned compounds which give dovants are LiPF ₆ , LiSbF ₆ , LiAsF ₆ , L
iClO ₄ , NaClO ₄ , KI, KPF ₆ , KSbF ₆ ,
KAsF _6, KClO _4, [(n-Bu) ₄ N] (+) -
CF ₃ SO ₃ (−), [(n-Bu) ₄ N] (+) · Cl
O ₄ (−), [(n-Bu) ₄ N] (+) · BF
₄ (−), LiAlCl ₄ , LiBF ₄ , LiCF ₃ SO ₃
And the like.

The solvent constituting the electrolyte solution is not particularly limited, but a solvent having a relatively large polarity is preferably used. Specifically, propylene carbonate, ethylene carbonate, benzonitrile, acetonitrile,
Tetrahydrofuran, 2-methyltetrahydrofuran,
one or two of organic solvents such as γ-butyrolactone, dioxolane, triethylphosphate, triethylphosphite, dimethylformamide, dimethylacetamide, dimethylsulfoxide, dioxane, dimethoxyethane, polyethylene glycol, sulfolane, dichloroethane, chlorobenzene, nitrobenzene, etc. Mixtures of more than one species can be mentioned.

As the separator (j), a separator having low resistance to the ion migration of the electrolyte solution and excellent in solution retention is used. For example, a glass fiber filter; a polymer pore filter such as polyester, Teflon, polyflon, and polypropylene; a nonwoven fabric; or a nonwoven fabric made of glass fiber and a polymer thereof can be used. The separator can also be used as a fusible film as described above.

Examples of the solid electrolyte include inorganic and organic electrolytes, and organic electrolytes are exemplified in terms of flexibility and the like. For example, in an inorganic system, for example, AgC
metal halides such as 1, AgBr, AgI, and LiI; and RbAg ₄ I ₅ and RbAg ₄ I ₄ CN.
Further, in the organic system, polyethylene oxide, polypropylene oxide, polyvinylidene fluoride, polyacrylamide, etc. as a polymer matrix, a composite obtained by dissolving the above-described electrolyte salt in a polymer matrix,
Alternatively, a crosslinked product thereof, a low molecular weight polyethylene oxide, a polymer solid electrolyte in which an ionic dissociating group such as a crown ether is grafted to the polymer main chain or a polymer solid electrolyte containing an electrolyte solution in a high molecular weight polymer, The electrolyte may be used alone, but is preferably used in combination with a separator for the purpose of making the current density uniform and preventing a short circuit.

As the current collector (c), it is preferable to use a metal film such as nickel, titanium, copper, stainless steel or the like as a substrate at the same time as the current collector. It may be made of a material.

As the partition wall (h) used in the battery of the present invention, an insulator which is not reactive with the battery element and can be adhered to the current collector or the exterior is used. Specifically, it is composed of a resin layer of polyethylene, polypropylene, nylon, polyester or the like and an adhesive layer. As the adhesive layer, heat-fusible resin such as modified polyethylene, modified polypropylene,
Epoxy-based, acrylic-based, and ceramic-based adhesives can be exemplified. Among these, a combination of polyethylene and polypropylene as the resin layer and modified polyethylene and modified polypropylene as the adhesive layer is most preferable in terms of adhesion to the current collector and stability.

[0016]

【Example】

Example 1 As shown in FIG. 1, 130 × 130 mm, thickness 3 was formed on a SUS304 plate (c) having a size of 140 × 140 mm and a thickness of 50 μm.
A heat-sealing film in which a polyaniline sheet (b) of 00 μm is arranged, the electrode (b) and the SUS plate (c) are bonded with a conductive adhesive, and a number of holes (g) are opened as shown in FIG. (A
2), the electrode (b) was fused and fixed by heat at 120 ° C. to form a positive electrode (d3) with a current collector substrate shown in FIG. Next, a polypropylene partition wall (h) having an outer shape of 140 × 140 mm, a width of 5 mm, and a thickness of 350 μm, the surface of which is modified to have a metal-fusing property, is laminated on the current collector, and bonded to the current collector by heat fusion. did. A polymer solid electrolyte composition obtained by mixing 80% of an electrolyte solution of 3MLiBF ₄ / (propylene carbonate + dimethoxyethane) (volume ratio 7: 3), 19.2% of ethoxydiethylene glycol acrylate, and 0.8% of methylbenzoylformate was used. Positive electrode (d
After infiltration into 1), a 25 μm polypropylene pore filter (trade name: Celgard) (j) was laminated, irradiated with a high-pressure mercury lamp, and an electrolyte was laminated on the positive electrode (d1). Meanwhile, 1
SUS304 plate of 40 × 140 mm and thickness of 50 μm (c
1) Li having a thickness of 100 μm was bonded thereon in the same manner as the positive electrode, and the above-mentioned polymer solid electrolyte composition was applied on Li, and then irradiated with a high-pressure mercury lamp to laminate the electrolyte on Li. As shown in FIG. 4, an electrode (d1) with a current collector in which a positive electrode / electrolyte is laminated and a negative electrode (c1) with a current collector substrate in which a negative electrode (Li) / electrolyte are laminated are bonded together and the partition wall portion is thermally fused. Perform sealing, 140mm × 140mm × 0.45mm
A thin sheet-shaped battery was prepared. This battery was charged to 3.7V and then discharged to 2.5mA at 50mA.
A discharge capacity of 120 mAh was obtained. Thereafter, the battery was subjected to a bending test, and no particular change was observed in its performance.

Example 2 As a fusion film, a film having many holes formed in a portion corresponding to a fusion portion with a sheet electrode as shown in FIG.
3) A sheet-like thin electrode (d2) shown in FIG. 3 was prepared in the same manner as in Example 1 except that a positive electrode produced also as a separator was used. At this time, a discharge capacity of 150 mAh was obtained in the charge / discharge test under the same conditions as in Example 1, even though the thickness was reduced to 0.42 mm. afterwards,
The battery was subjected to a bending test, and no particular change was observed in its performance.

Comparative Example 1 A positive electrode member was prepared in the same manner as in Example 1 except that a polyaniline sheet having a size of 130 × 130 mm and a thickness of 300 μm was fixed on a SUS304 plate having a size of 140 × 140 mm and a thickness of 50 μm using only a conductive adhesive. A sheet-shaped thin battery was manufactured. At this time, in the charge / discharge test under the same conditions as in Example 1, 15
Although a discharge capacity of 0 mAh could be achieved, a clear decrease in capacity was observed after a few cycles. Further, when the battery was subjected to a bending test thereafter, the discharge capacity was reduced to less than half, and it is considered that the polyaniline sheet of the positive electrode was largely detached from the current collector substrate.

[0019]

According to the present invention, an electrode with a current collector substrate in which a sheet-like electrode and a current collector substrate are firmly bonded by a fusible sheet can be obtained. A highly reliable sheet-shaped thin battery with high performance is provided.

[Brief description of the drawings]

FIG. 1 shows a configuration in which a large-area sheet-shaped electrode (b) is fixed using a fusion film (a1) provided with an opening (e) in a current collector substrate (c), and It is a figure showing sheet-like electrode (d1) fixed with a constituent member.

FIG. 2 shows a sheet-like electrode (b) of FIG. 1 and a fusion film (a).
It is a figure which shows the state which provided many holes (g) in the fusion part (f) with 2).

FIG. 3 shows a porous fused film / separator (a3), a sheet-like electrode (b), a current collector substrate (c), and a sheet composed of these members, which are components of the positive electrode member of Example 2. It is a figure which shows a shape positive electrode (d2).

FIG. 4 is a diagram showing a combination of battery constituent members such as a positive electrode, a separator (j), a partition (h), a negative electrode (i), and a current collector substrate (c1) using the electrode with substrate (d3) shown in FIG. It is.

[Explanation of symbols]

(A) A fusing film (a1) A fusing film having an opening (a2) A fusing film in which a number of holes are provided in a portion corresponding to a fusing surface with a sheet-like electrode (a3) A sheet-like electrode (B) Sheet-shaped electrode (c) Current collector substrate (c1) Current collector substrate (d) Electrode (current collector) (D1) Electrode (with current collector substrate) (d2) Electrode (with current collector substrate) (d3) Positive electrode (with current collector substrate) (e) Opening (hole) (f) Sheet Fused surface between electrode and fusible film (f1) Fused portion between sheet electrode and porous fusible film (f2) Fused surface between current collector substrate and fusible film (g) Fused portion ( f) or a number of holes provided in (f1) (h) Partition walls (i) Negative electrode (with current collector substrate) (j Separator

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Toshiyuki Kabata 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (56) References JP-A-6-45005 (JP, A) JP 54-18041 (JP, A) JP-A 4-76253 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01M 4/02 H01M 4/64 H01M 10/40

Claims (4)

(57) [Claims] 1. A sheet-like electrode covered and fixed on a current collector substrate with a current collector substrate and a fusible film, wherein the fusible film is a porous film, and at least the outside of the sheet-like electrode. A sheet-shaped electrode having an opening having a size and a shape capable of forming an overlapping portion with the sheet-shaped electrode at a peripheral portion. 2. A sheet-like electrode coated and fixed on a current collector substrate with a current collector substrate and a fusible film, wherein the fusible film is formed at least at the outer peripheral edge of the sheet-like electrode. It has an opening of a size and shape capable of forming an overlapping portion with the electrode,
A sheet-like electrode, wherein a number of holes are provided in the overlapping portion. 3. The sheet-like electrode covered and fixed on the current collector substrate with a current collector substrate and a fusible film, wherein the fusible film is a porous film, and at least the outside of the sheet-like electrode. A sheet-shaped electrode having an opening having a size and a shape capable of forming an overlapping portion with the sheet-shaped electrode at a peripheral portion, wherein a number of holes are provided in the overlapping portion. 4. A thin sheet-shaped battery, wherein at least one of the two electrodes is constituted by the electrode according to claim 1.