JP5838322B2 - Thin battery - Google Patents

Description

  The present invention relates to a flexible thin battery. More specifically, the present invention relates to an improvement in an exterior body that accommodates an electrode group.

  In recent years, with the miniaturization and high performance of electronic devices, batteries used as power sources are also required to be small and light. As such a battery, a thin battery used in fields such as an IC card incorporating a microcomputer chip and RFID (Radio Frequency Identification) has been developed.

  A typical thin battery includes, for example, a sheet-shaped electrode group in a bag-shaped exterior body formed of a laminate film in which a resin film is laminated on both surfaces of an aluminum foil, as disclosed in Patent Document 1 below. Then, what sealed the electrode group by heat-sealing an opening part is known.

  Further, for example, Patent Document 2 below describes, as a structure of an outer package of a thin battery, a flexible polymer base film that is attached to a battery and encloses the battery, and a battery on which the battery is encapsulated and sealed. A battery package for a thin battery having a deposited flexible inorganic material layer is disclosed.

  By the way, in recent years, for example, as disclosed in Patent Document 3 below, a transdermal administration device (iontophoresis process) using the principle of iontophoresis for controlling the permeability of a drug from the skin using electricity. Development of a biometric information acquisition device that acquires biometric information by bringing it into contact with the skin of a living body, as disclosed in Patent Document 4 below, is being promoted. In addition, iontophoresis is a method in which a voltage is applied between an ionic drug placed under one electrode and the other electrode, and the ionic drug is accelerated by the electric field to penetrate subcutaneously.

JP 2000-258881 A JP-A-6-23179 JP-A-6-23179 JP 2011-92543 A

  For example, in a conventional thin battery used as a power source for an IC card, the main body of the IC card itself has rigidity, and the thin battery is supported by such a card body. The level was sufficient in the range lower than the flexibility of the card body. The IC card is not used so as to be bent at an acute angle such as an angle of 90 degrees or less. On the other hand, as described above, as an iontophoresis transdermal administration device and a biological information acquisition device for acquiring biological information used in contact with the skin of a living body, the device is made thin, and the skin Even if the living body moves in a contacted state, it may be required to be greatly deformed so as to follow the movement of the skin. And in order to raise the freedom degree of design of such an apparatus, the thin battery which was excellent by flexibility at a high level is calculated | required. However, when a thin battery that is not sufficiently flexible, such as a conventional thin battery, is used as a power source for a device that is used in contact with the skin of a living body as described above, It is too hard and may cause the user to feel uncomfortable.

  An object of this invention is to provide the thin battery excellent in flexibility.

One aspect of the present invention includes a sheet-like electrode group including a positive electrode, a negative electrode, and an electrode structure in which an electrolyte layer interposed between the positive electrode and the negative electrode is laminated, and a film outer package that hermetically stores the electrode group. The film outer package is formed by laminating a first resin film, a vapor deposition layer of a metal material or an inorganic material having a thickness of 0.01 to 1 μm, and a second resin film, which are sequentially laminated on one surface of the first resin film. and it is formed from a laminated film including a deposition layer containing laminate film was, the electrode group of flexural modulus of der Ru thin battery below 300 MPa.

  The present inventor has found that the mechanical properties of the exterior body, which has not been noticed so far, have a great influence on the flexibility when considering the mechanical behavior when the thin battery is bent. Specifically, as shown in FIG. 7, when the thin battery 100 including the electrode group 90 is folded, the outer side of the outer package 101 extends and the inner side is compressed. I noticed that it has a great influence on flexibility. Conventionally, a laminated film in which a thick aluminum foil is used as a gas barrier layer and a resin layer is laminated has been widely used for an outer package of a thin battery. In the present invention, it has been found that by using a thin gas barrier layer made of a vapor deposition film instead of a thick gas barrier layer such as a thick aluminum foil, it is possible to greatly improve the elongation characteristics of the outer package of a thin battery. . In addition, although the gas barrier property may be lowered to some extent in battery applications that are used for a long period of time, an excessively high gas barrier property is not required in the case of battery applications that are used in a short period of time.

In the thin type battery, and a tensile modulus of the laminate film is 100MPa or less, the thickness of the conductive pole group not more than 700μm is preferable from the viewpoint of greater flexibility can be obtained.

Moreover, it is preferable that a negative electrode contains lithium as a negative electrode active material, and a vapor deposition layer has a withstand voltage of 3 volts (vs.Li ⁺ / Li) or more. When the positive electrode and the barrier layer are microscopically short-circuited due to burrs at the end of the positive electrode, the gas barrier layer may be oxidized and damaged. In such a case, damage due to elution or decomposition of the gas barrier layer can be suppressed by using the vapor deposition layer having a high withstand voltage as described above as the gas barrier layer. As a material for forming such a deposited layer having a withstand voltage of 3 volts (vs. Li ⁺ / Li) or more, a metal material such as aluminum, titanium, nickel, iron, platinum, gold, silver, palladium, Examples include inorganic oxide materials such as silicon oxide, magnesium oxide, and aluminum oxide.

  In the above thin battery, the negative electrode includes lithium as a negative electrode active material, the first resin film is a polyamide film having a thickness of 10 to 100 μm, and the second resin film is a polyolefin film having a thickness of 20 to 100 μm. The total thickness of the laminate film is preferably 30 to 200 μm, and the first resin film is disposed on the outer surface side of the film exterior body, and the second resin film is disposed on the inner surface side of the film exterior body. Since the polyolefin film has a relatively high reduction resistance, it effectively suppresses the reduction of the vapor deposition layer, which is a gas barrier layer, and the polyamide film has a high chemical resistance, mechanical strength, abrasion resistance, etc. Damage from the outside can be effectively suppressed.

  Another aspect of the present invention is a sheet-like electrode group including an electrode structure in which a positive electrode, a negative electrode, and an electrolyte layer interposed between the positive electrode and the negative electrode are laminated, and a film outer package that hermetically stores the electrode group; The film outer package is composed of a first laminate film and a second laminate film having a higher tensile elastic modulus than the first laminate film, which are joined to each other at the peripheral ends. A vapor deposition layer-containing laminate film obtained by laminating one resin film, a metal material or inorganic material vapor deposition layer having a thickness of 0.01 to 1 μm, and a second resin film, which are sequentially laminated on one surface of the first resin film. It is a thin battery formed from. As described above, when the thin battery is folded, the outer side of the outer package extends and the inner side is compressed. Therefore, as a thin battery exterior body, by making the tensile elastic modulus of the first laminate film located outside when folded to be lower than the tensile elastic modulus of the second laminate film located inside, the thin battery exterior The flexibility of the body can be greatly improved. In addition, by using a metal foil-containing laminate film comprising a thick metal foil such as an aluminum foil as a gas barrier layer as the second laminate film located on the inside, an exterior having an excellent balance between gas barrier properties and flexibility A thin battery with a body is obtained. In such a thin battery, it is preferable that the flexural modulus of the electrode group is 300 MPa or less, the tensile modulus of the first laminate film is 100 MPa or less, and the tensile modulus of the second laminate film is higher than 100 MPa. .

  ADVANTAGE OF THE INVENTION According to this invention, the thin battery excellent in flexibility can be provided.

FIG. 1 is a partially broken perspective view of a thin battery 10 according to an embodiment. 2 is a schematic cross-sectional view taken along the line II ′ of FIG. FIG. 3 is a schematic cross-sectional view of the vapor deposition layer-containing laminate film 14 that forms the film outer package 4. FIG. 4 is a schematic cross-sectional view of a thin battery 20 according to another embodiment. FIG. 5 is a schematic diagram showing an example of use of an electronic device in which the thin battery 10 is mounted. FIG. 6 is an explanatory diagram for explaining a method for measuring the capacity retention rate after bending storage in the example. FIG. 7 is an explanatory diagram for explaining how to apply force when the thin battery is bent.

  An embodiment of a thin battery of the present invention will be described with reference to the drawings. FIG. 1 is a partially broken perspective view of a thin battery 10 of this embodiment. The thin battery 10 of the present embodiment is a nonaqueous electrolyte battery having a laminate film as an outer package. In FIG. 1, 1 is an electrode group, 2 is a positive electrode lead connected to the positive electrode current collector of the electrode group 1, 3 is a negative electrode lead connected to the negative electrode current collector of the electrode group 1, and 4 is an electrode group 1 sealed It is the film exterior body to store.

  As shown in FIG. 1, a thin battery 10 includes a sheet-like electrode group 1 including a positive electrode, a negative electrode, and an electrode structure in which an electrolyte layer interposed between the positive electrode and the negative electrode is laminated. It is hermetically sealed and formed. The positive electrode lead 2 connected to the positive electrode current collector of the electrode group 1 and the negative electrode lead 3 connected to the negative electrode current collector are led out from the film outer package 4 as a positive electrode terminal and a negative electrode terminal, respectively.

  2 is a schematic cross-sectional view taken along the line II ′ of FIG. As shown in FIG. 2, the electrode group 1 includes a positive electrode 5 that occludes and releases lithium, a negative electrode 6 that occludes and releases lithium, and an electrolyte layer 7 that is interposed between the positive electrode 5 and the negative electrode 6. A group. The positive electrode 5 includes a positive electrode active material layer 5a and a positive electrode current collector 5b, and the negative electrode 5 includes a negative electrode active material layer 6a and a negative electrode current collector 6b.

The positive electrode 5 is formed, for example, by applying a positive electrode active material layer forming slurry to the surface of the positive electrode current collector 5b, and drying and rolling. The positive electrode active material layer forming slurry is prepared, for example, by mixing and mixing a positive electrode active material, a binder, and a conductive material in a dispersion medium. Specific examples of the positive electrode active material include, for example, manganese dioxide; fluorinated graphite; thionyl chloride; lithium-containing composite oxide mainly composed of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, etc .; LiYPO ₄ , And olivine-type lithium phosphate represented by Li ₂ YPO ₄ F (wherein Y represents at least one element selected from the group consisting of Co, Ni, Mn, and Fe). Specific examples of the binder include, for example, polyvinylidene fluoride, polytetrafluoroethylene, polyhexafluoropropylene, styrene butadiene rubber, and modified acrylic rubber. Specific examples of the conductive agent include graphites such as natural graphite and artificial graphite; carbon blacks such as acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black; carbon fiber and metal Examples thereof include conductive fibers such as fibers. Specific examples of the dispersion medium include dimethylformamide, dimethylacetamide, methylformamide, N-methyl-2-pyrrolidone, dimethylamine, acetone, and cyclohexanone. Specific examples of the positive electrode current collector include a metal foil made of stainless steel, titanium, aluminum, an aluminum alloy, or the like. Note that the positive electrode current collector may be a deposited film formed in a thin film shape using a plasma chemical vapor deposition method (PVD method) or a chemical vapor deposition method (CVD method) instead of the metal foil.

  The negative electrode 6 is formed, for example, by applying a slurry for forming a negative electrode active material layer on the surface of the negative electrode current collector 6b, and drying and rolling. The slurry for forming a negative electrode active material layer is prepared, for example, by mixing and mixing a negative electrode active material, a binder, and a conductive agent, if necessary, in a dispersion medium. Specific examples of the negative electrode active material include, for example, lithium or lithium alloys, various carbon materials such as graphite materials, occlusion of lithium by alloying with lithium at the time of negative electrode potential, and release of lithium during discharge. And alloy-based negative electrode active materials such as silicon-based active materials and tin-based active materials. As the binder, the dispersion medium, and the conductive agent, the same binder as that used for the positive electrode can be used. Specific examples of the negative electrode current collector include a metal foil made of copper, copper alloy, stainless steel, titanium, nickel, or the like. The negative electrode current collector may also be formed on the thin film by using a PVD method or a CVD method instead of the metal foil. Moreover, as a negative electrode, you may use lithium or lithium alloy which is a negative electrode active material with metal foil. The negative electrode active material layer may be formed by pressing a lithium or lithium alloy metal foil, which is a negative electrode active material, onto a negative electrode current collector.

  As the electrolyte layer 7, for example, a polymer electrolyte, a solid electrolyte, a nonaqueous electrolytic solution impregnated in a separator, or the like can be used. Among these, a polymer electrolyte or a solid electrolyte is particularly preferable from the viewpoint that leakage can be suppressed.

The polymer electrolyte is prepared, for example, by integrating an electrolytic solution obtained by mixing a lithium salt and a nonaqueous solvent with a matrix polymer. Further, such a polymer electrolyte may be fixed by impregnating a separator or applying it on an electrode. Specific examples of the lithium salt include, for example, LiClO ₄ , LiBF ₄ , LiPF ₆ , LiAlCl ₄ , LiSbF ₆ , LiSCN, LiCF ₃ SO ₃ , LiCF ₃ CO ₂ , LiAsF ₆ , LiB ₁₀ Cl ₁₀ , lower aliphatic carboxylic acid. Lithium, LiCl, LiBr, LiI, LiBCl ₄ , borates, imide salts and the like can be mentioned. Specific examples of the non-aqueous solvent include, for example, cyclic carbonates such as propylene carbonate, ethylene carbonate, and butylene carbonate; chain carbonate esters such as diethyl carbonate, ethyl methyl carbonate, and dimethyl carbonate; γ-butyrolactone, γ-valero And cyclic carboxylic acid esters such as lactones. Specific examples of the matrix polymer include, for example, polyvinylidene fluoride (PVdF), a copolymer containing vinylidene fluoride (VdF) and hexafluoropropylene (HFP) as repeating units, vinylidene fluoride (VdF) and trifluoroethylene. Fluoropolymers such as copolymers containing (TFE) in repeating units; silicon gels; acrylic gels; acrylonitrile gels; polyphosphazene modified polymers; polyethylene oxides; polypropylene oxides and their composite polymers, cross-linked polymers, modified polymers, etc. Is mentioned.

  The solid electrolyte can be formed, for example, by depositing a vapor deposition film of a lithium ion conductor on the positive electrode or the negative electrode by using a PVD method or a CVD method. Specific examples of the lithium ion conductor include lithium sulfide.

  The non-aqueous electrolyte impregnated in the separator is a non-aqueous electrolyte prepared by mixing a lithium salt and a non-aqueous solvent as described above into a separator that is a resin porous membrane interposed between a positive electrode and a negative electrode. It is prepared by impregnating. As a specific example of the resin porous membrane, for example, a microporous membrane formed from a resin such as polyolefin such as polyethylene or polypropylene, or polyamide such as polyamideimide is preferably used.

  The positive electrode lead 2 and the negative electrode lead 3 are connected to, for example, a positive electrode current collector or a negative electrode current collector, respectively, by welding. For example, an aluminum lead is preferably used as the positive electrode lead. Moreover, as a negative electrode lead, a copper lead, a copper alloy lead, a nickel lead, etc. are used preferably, for example.

As shown in FIGS. 1 and 2, the electrode group 1 has a sheet shape. The electrode group 1 preferably has high flexibility. Therefore, the thickness of the electrode group 1 is preferably 1000 μm or less, more preferably 700 μm or less, and particularly preferably 400 μm or less. Although the minimum of the thickness of an electrode group is not specifically limited, From the point which can ensure practical capacity | capacitance, it is preferable that it is 10 micrometers or more, Furthermore, 50 micrometers or more. As a measure of the flexibility of the electrode group, the flexural modulus measured by the method described later is 300 MPa or less , preferably 200 MPa or less, particularly preferably 100 MPa or less.

  Next, with reference to FIG. 3, the vapor deposition layer containing laminated film 14 which forms the film exterior body 4 is demonstrated in detail. FIG. 3 is a schematic cross-sectional view of the vapor deposition layer-containing laminate film 14 that forms the film outer package 4. The vapor deposition layer-containing laminate film 14 includes a first resin film 14a, a vapor deposition layer 14b of a metal material or an inorganic material having a thickness of 0.01 to 1 μm, which is sequentially laminated on one surface of the first resin film 14a, and a second layer. It is a laminated body containing the layer which consists of resin film 14c.

  The deposited layer-containing laminate film 14 is formed by forming a deposited layer 14b of a metal material or an inorganic material having a thickness of 0.01 to 1 μm on one surface of the first resin film 14a, and further laminating the second resin film 14c. Manufactured. The resin for forming the first resin film and the second resin film is not particularly limited. Specifically, for example, polyolefin such as polyethylene and polypropylene; polyester such as polyethylene terephthalate and polybutylene terephthalate; polyamide 6, polyamide 11 , Polyamide 12, polyamide 46, polyamide 9T, polyamide 66 and the like; or modified products thereof. The thicknesses of the first resin film and the second resin film are 10 to 100 μm, more preferably 15 to 80 μm, respectively, while maintaining reduction resistance, gas barrier properties, friction resistance, etc. It is preferable from the viewpoint that the property can be maintained.

  The vapor deposition layer 14b is a layer that functions as a gas barrier layer. A negative electrode active material, particularly a negative electrode active material containing lithium, has high reducibility, and when it comes into contact with moisture in the air, it tends to react with moisture quickly and be easily oxidized and corroded. The vapor deposition layer 14b is disposed for the purpose of suppressing oxidation and corrosion of the negative electrode active material.

  The vapor deposition layer 14b is formed by vapor-depositing a metal material or an inorganic material on one surface of the first resin film 14a so as to have a thickness of 0.01 to 1 μm. Specific examples of the vapor deposition method include vacuum vapor deposition, sputtering, ion plating, laser ablation, chemical vapor deposition, plasma chemical vapor deposition, and thermal spraying. Of these, the vacuum evaporation method is particularly preferably used.

Although the material used for formation of the vapor deposition layer 14b is not specifically limited, The metal material or inorganic material which can form the vapor deposition layer which has a withstand voltage of 3 volts or more on the basis of lithium (vs.Li ⁺ / Li), specifically, For example, metal materials such as aluminum, titanium, nickel, iron, platinum, gold, silver, and palladium, and inorganic oxide materials such as silicon oxide, magnesium oxide, and aluminum oxide are preferable. By using a vapor deposition layer having an excellent withstand voltage as the gas barrier layer, damage due to oxidation or the like of the gas barrier layer can be suppressed. Moreover, among these, aluminum, silicon oxide, and aluminum oxide are particularly preferable from the viewpoint of excellent balance between flexibility and gas barrier properties of the obtained deposited layer-containing laminate film. The withstand voltage means an elution potential eluted in the electrolyte in the case of a metal material, and a decomposition potential in the case of an inorganic material.

  The thickness of a vapor deposition layer is 0.01-1 micrometer, Preferably it is 0.01-0.5 micrometer, More preferably, it is 0.02-0.2 micrometer. When the thickness of the vapor deposition layer exceeds 1 μm, the flexibility of the obtained vapor deposition layer-containing laminate film becomes poor, and as a result, the flexibility of the thin battery becomes poor. Moreover, when the thickness of a vapor deposition layer is less than 0.01 micrometer, the gas barrier property of the vapor deposition layer containing laminated film obtained will become scarce.

  The total thickness of such a deposited layer-containing laminate film is preferably 30 to 200 μm, more preferably 30 to 160 μm. If the total thickness of the vapor deposition layer-containing laminate film is too thin, the strength of the exterior body and the reliability of the gas barrier performance tend to decrease. If it is too thick, the flexibility of the resulting vapor deposition layer-containing laminate film As a result, the flexibility of thin batteries tends to be poor.

  In addition, the vapor deposition layer-containing laminate film has a tensile modulus measured by a method as described later of 100 MPa or less, and further 60 MPa or less to maintain the flexibility of a thin battery having a sheet-like electrode. To preferred. Although the minimum of a tensile elasticity modulus is not specifically limited, It is preferable that it is 10 Mpa or more practically.

  Among the laminated layer-containing laminate films, in particular, the first resin film is a polyamide film having a thickness of 10 to 100 μm, the second resin film is a polyolefin film having a thickness of 20 to 100 μm, and the total thickness is What is 30-200 micrometers is especially preferable from the point which is excellent in the balance of flexibility, gas barrier property, and a mechanical characteristic.

  As shown in FIGS. 1 and 2, the deposited layer-containing laminate film is used as a material for forming a film outer package 4 that hermetically houses the electrode group 1. For example, the outer peripheral part of the vapor deposition layer-containing laminate film cut into a predetermined size is used as a heat-sealing part, and the heat-sealing part is heat-sealed and joined to seal the electrode group 1. Is formed into a film outer package 4 for the purpose. Then, after storing the electrode group 1 in the film outer package 4 with one end of each of the positive electrode lead 2 and the negative electrode lead 3 being led out, the thin battery 10 is obtained by sealing.

  The total thickness of the electrode group of the thin battery and the film outer package is preferably 1 mm or less, more preferably 0.6 mm or less, and particularly preferably 0.3 mm or less. When the total thickness of the electrode group of the thin battery and the film outer package is too thick, the flexibility is lowered.

  In addition, in this embodiment, although the example using the film exterior body formed only from the vapor deposition layer containing laminate film by joining the vapor deposition layer containing laminate films as described above was representatively described in detail, the vapor deposition layer As shown in FIG. 4, a vapor deposition layer-containing laminate film is used as the first laminate film 21, and the second laminate film 22 is higher in tension than the first laminate film, instead of the film outer package formed only from the contained laminate film. Using a film outer package bonded to each other using another laminate film having an elastic modulus, specifically, a metal foil-containing laminate film provided with a thick metal foil such as an aluminum foil as a gas barrier layer A form like the thin battery 20 may be sufficient. According to such a film exterior body, the 1st laminate film 21 which is a vapor deposition layer containing laminate film contributes to improving the flexibility of a film exterior body greatly, and the 2nd laminate film which is a metal foil containing laminate film 22 contributes to securing gas barrier properties. Therefore, a thin battery provided with an exterior body having an excellent balance between gas barrier properties and flexibility can be obtained. In this case, the film outer package of the thin battery 20 is arranged such that the deposited layer-containing laminate film is positioned on the outer side when folded, and the metal foil-containing laminate film on the inner side when folded. It is preferable to arrange the battery so that is located. By arranging in this way, sufficient flexibility of the thin battery can be secured.

  The thin battery excellent in flexibility as described above can be used without any particular limitation as a power source of an electronic device in which flexibility is particularly required. Specifically, it is particularly preferably used as a power source for an iontophoresis transdermal drug delivery device used in contact with the skin of a living body or a biological information acquisition device for acquiring biological information. FIG. 5 shows, as an example, a schematic explanatory diagram of an iontophoresis transdermal administration device 30 provided with the thin battery 10 of the present embodiment as a power source. An iontophoretic transdermal administration device 30 including an anode 31 and a cathode 32 is used in close contact with a curved human arm 40. Since the thin battery 10 has high flexibility, even if it is used as a power source of an electronic device that is in close contact with a curved portion such as a human arm, the thin battery 10 can be easily deformed in accordance with the curvature.

  The present invention will be described more specifically with reference to the following examples. The scope of the present invention is not construed as being limited by the examples.

[Example 1]
(Production of electrode group)
100 parts by mass of electrolytic manganese dioxide as a positive electrode active material, 5 parts by mass of acetylene black as a conductive agent, and 5 parts by mass of polyvinylidene fluoride (PVDF) as a binder are added to an appropriate amount of N-methyl-2-pyrrolidone (hereinafter referred to as NMP), A positive electrode mixture paste was prepared by mixing. Then, a positive electrode mixture paste is applied to one side of an aluminum foil having a thickness of 15 μm to be a positive electrode current collector, dried, rolled, and cut into a size of 50 mm × 50 mm to obtain a positive electrode having a total thickness of 115 μm. It was. Subsequently, an aluminum positive electrode lead was welded to the positive electrode current collector.

  On the other hand, on one side (surface roughness 2.6 μm) of a 20 μm-thick copper foil punched into a 50 mm × 50 mm square having a 12 mm × 5 mm protrusion on one side, a lithium metal foil (50 mm × 50 mm, thickness 20 μm) was pressure-bonded with a linear pressure of 100 N / cm. Then, a copper electrode lead having a width of 3.0 mm and a length of 20 mm was ultrasonically welded.

On the other hand, lithium perchlorate (LiClO ₄ ) as an electrolyte salt was added to a non-aqueous solvent obtained by mixing at a ratio of propylene carbonate (PC): dimethoxyethane (DME) = 6: 4 (mass ratio) at 1 mol / liter. A liquid electrolyte was prepared by dissolving to kg. Then, by using dimethyl carbonate (DMC) as a solvent as a medium, the obtained liquid electrolyte and matrix polymer are mixed so that the ratio of matrix polymer: liquid electrolyte = 1: 10 (mass ratio) is obtained. A polymer electrolyte solution was prepared. As the matrix polymer, a copolymer of hexafluoropropylene and polyvinylidene fluoride (hexafluoropropylene content: 7%) was used. The obtained gel polymer electrolyte solution was uniformly applied to both sides of the separator made of porous polyethylene and the positive electrode active material layer, and the positive electrode and the separator were impregnated with the gel polymer electrolyte by volatilizing the solvent. .

  On the surface of the positive electrode impregnated with the gel polymer electrolyte, a negative electrode is laminated so that the active material layers face each other through a separator having a thickness of 35 μm impregnated with the gel polymer electrolyte, and then 90 ° C., 0.5 MPa Was subjected to hot pressing for 1 minute to produce a thin battery electrode group having a thickness of 190 μm.

(Production of thin battery)
The first resin film is a film made of polyamide 6 having a thickness of 15 μm, the second resin film is a film made of polyethylene film having a thickness of 35 μm, and the thickness is between the first resin film and the second resin film. A sheet-like bag made of a laminate film a having a total thickness of about 50 μm provided with a 0.05 μm aluminum oxide vapor deposition layer was prepared. Specifically, the laminate film a is cut into a rectangular shape having a size of 60 mm × 65 mm, and the obtained two pieces of the laminate film a are overlapped, and a peripheral edge portion having a width of about 3 mm on the three sides. And processed into a bag having one opening. Then, the electrode group described above is accommodated in the obtained bag body, and the positive electrode lead and the negative electrode lead are led out to the outside from the opening portion, and the opening portion is heat-sealed so that the total thickness is about 0.3 mm. Battery A was obtained.

(Evaluation)
The characteristics of the obtained thin battery and electrode group were evaluated by the following methods.

<Bending elastic modulus of electrode group>
Based on the measuring method of JIS K7171, the bending elastic modulus of the electrode group was measured. In addition, the strip-shaped test piece of length 50mm, width 50mm, and thickness 0.19mm was used for the shape of the test piece of an electrode group. In addition, the support base used the thing of distance L30mm between fulcrums, and tip radius R2mm. Further, an indenter having a tip radius R of 5 mm was moved at 100 mm / min, and a load was applied to the central portion of the test piece.

<Tensile elastic modulus of laminate film>
The laminate film was cut into a tensile test No. 3 dumbbell with a parallel part width of 5 mm and a distance between marked lines of 20 mm, and a tensile test was conducted using a universal testing machine at a tensile speed of 5 mm / min in accordance with JIS K7161. Asked.

<Flexibility of thin battery>
The flexibility of the thin battery was determined by evaluating the flexural modulus. Specifically, the flexural modulus of the thin battery was measured according to the measurement method of JIS K7171. The obtained thin battery was used as it was as a test piece. A support base having a distance between supporting points of L 30 mm and a tip radius of R 2 mm was used. Further, an indenter having a tip radius R of 5 mm was moved at 100 mm / min, and a load was applied to the central portion of the test piece.
<Battery capacity of thin battery>
Under an environment of 25 ° C., the thin battery was discharged at a current density of 250 μA / cm ² until the closed circuit voltage reached 1.8 V, and the discharge capacity was determined. The current density refers to a current value per unit area on the surface in the thickness direction of the positive electrode active material layer.

<Capacity maintenance ratio after bending storage>
The thin battery was discharged at a current density of 250 μA / cm ^{2 in} a 25 ° C. environment until the closed circuit voltage reached 3V. Thereafter, as shown in FIG. 6, the portions closed by thermal welding at both ends of the thin battery 30 (thin battery A) were fixed by a stretchable fixing member 51 arranged horizontally so as to face each other. And as shown in FIG. 6, the jig | tool 52 which has a curved surface part whose curvature radius R is 20 mm was pressed against the thin battery 30, and the thin battery 10 was deformed along the curved surface part. Thereafter, the jig 52 was pulled away from the thin battery 30 and the deformation was restored. This bending deformation was repeated 10,000 times. And the thin battery to which this 10,000 bending deformation process was given was preserve | saved for 90 days in a 60 degreeC environment. Then, a thin battery (untreated thin battery) that was not subjected to bending deformation processing and 90-day storage processing and a thin battery (thin battery after processing) that was subjected to 10,000 bending deformation processing and 90-day storage processing, respectively, Under an environment of 25 ° C., discharge was performed at a current density of 250 μA / cm ² until the closed circuit voltage reached 1.8 V, and the respective discharge capacities were obtained. And the following formula:
Capacity maintenance ratio after bending storage (%) = (discharge capacity of thin battery after treatment / discharge capacity of untreated thin battery) × 100
Thus, the capacity retention rate (%) after bending storage was determined.
The results are shown in Table 1.

[Example 2]
Instead of the laminate film a of Example 1 provided with a 0.05 μm thick aluminum oxide vapor deposition layer between the first resin film and the second resin film, a 0.05 μm thick silicon oxide vapor deposition layer is provided. A thin battery B was obtained and evaluated in the same manner as in Example 1 except that a laminate film b having a total thickness of about 50 μm was used. The results are shown in Table 1.

[Example 3]
Instead of the laminate film a of Example 1 provided with a 0.05 μm thick aluminum oxide vapor deposition layer between the first resin film and the second resin film, a 0.05 μm thick aluminum vapor deposition layer was used. A thin battery C was obtained and evaluated in the same manner as in Example 1 except that the provided laminate film c having a total thickness of about 50 μm was used. The results are shown in Table 1.

[Example 4]
Instead of the laminate film a of Example 1 provided with a 0.05 μm thick aluminum oxide vapor deposition layer between the first resin film and the second resin film, a 0.05 μm thick silicon nitride vapor deposition layer is provided. A thin battery D was obtained and evaluated in the same manner as in Example 1 except that a laminate film d having a total thickness of about 50 μm was used. The results are shown in Table 1.

[Example 5]
Instead of the laminate film a of Example 1 provided with a 0.05 μm thick aluminum oxide vapor deposition layer between the first resin film and the second resin film, a 0.2 μm thick silicon oxide vapor deposition layer is provided. A thin battery E was obtained and evaluated in the same manner as in Example 1 except that the laminate film e having a total thickness of about 50 μm and was used. The results are shown in Table 1.

[Example 6]
In place of the laminate film a of Example 1 provided with a 0.05 μm thick aluminum oxide vapor deposition layer between the first resin film and the second resin film, a 1 μm thick silicon oxide vapor deposition layer is provided. A thin battery E was obtained and evaluated in the same manner as in Example 1 except that the laminate film e having a total thickness of about 51 μm was used. The results are shown in Table 1.

[Example 7]
The laminate film b used in Example 2 was used as one cut piece as the two laminate films used for producing the bag. And as another cut piece, instead of the laminate film a of Example 1 provided with a vapor deposition layer of aluminum oxide having a thickness of 0.05 μm between the first resin film and the second resin film, A laminate film f having a total thickness of about 85 μm provided with an aluminum foil layer having a thickness of 35 μm was used. And the thin battery F was obtained and evaluated like Example 1 except having used the bag body which consists of the laminate film b and the laminate film f. The results are shown in Table 1.

[Comparative Example 1]
A thin battery G was obtained and evaluated in the same manner as in Example 1 except that the laminate film f used in Example 5 was used as the two laminated films used for producing the bag. The results are shown in Table 1.

From Table 1, it can be seen that all the thin batteries obtained in Examples 1 to 7 according to the present invention have a flexural modulus of 100 MPa or less and are extremely excellent in flexibility. On the other hand, the thin battery of Comparative Example 1 using a bag body made only of a laminate film having an aluminum foil having a thickness of 35 μm as a gas barrier layer as an exterior body has a bending elastic modulus of 390 MPa and low flexibility. I understand. In addition, when a particularly thin vapor deposition film is used as the gas barrier layer as in Example 1 to Example 5, it is more flexible than a thin battery having a thick vapor deposition layer as in Example 6. I understand that. In addition, among the vapor deposition layers, Example 4 using a silicon nitride film having a withstand voltage of less than 3 volts on the basis of lithium (vs. Li ⁺ / Li) is somewhat low in oxidation resistance, or may be subjected to bending storage. The capacity maintenance rate was low.

  Since the thin battery of the present invention is extremely excellent in flexibility, for example, an iontophoresis transcutaneous administration device that is used in contact with the skin of a living body or a biological information acquisition device that acquires biological information. It is preferably used as a power source.

DESCRIPTION OF SYMBOLS 1 Electrode group 2 Positive electrode lead 3 Negative electrode lead 4 Film exterior body 5 Positive electrode 6 Negative electrode 7 Electrolyte layer 10, 20, 30 Thin battery 14 Deposition layer containing laminated film 14a First resin film 14b Deposition layer 14c Second resin film 21 First One laminated film 22 Second laminated film

Claims (10)

A sheet-like electrode group comprising a positive electrode, a negative electrode, and an electrode structure in which an electrolyte layer interposed between the positive electrode and the negative electrode is laminated; and a film outer package that hermetically stores the electrode group,
The film exterior body is
A vapor deposition layer-containing laminate in which a vapor deposition layer of a metal material or an inorganic material having a thickness of 0.01 to 1 μm and a second resin film are laminated in order on one surface of the first resin film and the first resin film. It is formed from a laminate film that includes a film ,
Thin battery flexural modulus of the electrode group, characterized in der Rukoto below 300 MPa.   The thin battery according to claim 1, wherein the vapor deposition layer-containing laminate film has a tensile elastic modulus of 100 MPa or less. Thin battery of claim 1 or 2 thickness before Symbol electrode group is not more than 700 .mu.m. The thin battery according to any one of claims 1 to 3, wherein the negative electrode includes lithium as a negative electrode active material, and the vapor deposition layer has a withstand voltage of 3 volts (vs. Li ⁺ / Li) or more.   The thin battery according to claim 1, wherein the vapor deposition layer is made of at least one metal material selected from the group consisting of aluminum, titanium, nickel, iron, platinum, gold, silver, and palladium.   The thin battery according to claim 1, wherein the vapor deposition layer is made of at least one inorganic oxide material selected from the group consisting of silicon oxide, magnesium oxide, and aluminum oxide. The negative electrode includes lithium as a negative electrode active material;
The first resin film is a polyamide film having a thickness of 10 to 100 μm,
The second resin film is a polyolefin film having a thickness of 20 to 100 μm, and the total thickness of the laminate film is 30 to 200 μm,
The thin battery according to any one of claims 1 to 6, wherein the first resin film is disposed on an outer surface side of the film exterior body, and the second resin film is disposed on an inner surface side of the film exterior body. . A sheet-like electrode group comprising a positive electrode, a negative electrode, and an electrode structure in which an electrolyte layer interposed between the positive electrode and the negative electrode is laminated; and a film outer package that hermetically stores the electrode group,
The film exterior body is composed of a first laminate film and a second laminate film having a higher tensile elastic modulus than the first laminate film, which are joined to each other at a peripheral end,
The one laminate film is
A vapor deposition layer in which a vapor deposition layer of a metal material or an inorganic material having a thickness of 0.01 to 1 μm and a second resin film are laminated in order on one surface of the first resin film and the first resin film. A thin battery characterized in that it is formed from a laminate film.   The second laminate film is formed of a third resin film and a metal foil-containing laminate film in which a metal foil and a fourth resin film are laminated in order on one surface of the third resin film. The thin battery according to claim 8.   The bending elastic modulus of the electrode group is 300 MPa or less, the tensile elastic modulus of the first laminate film is 100 MPa or less, and the tensile elastic modulus of the second laminate film is higher than 100 MPa. Thin battery.

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