JP2019204749A - Thin battery and electronic apparatus - Google Patents

Abstract

To suppress cracks in a film exterior body of a thin battery.SOLUTION: A thin battery includes a power generation element, a film exterior body housing the power generation element, a reinforcement body disposed on the outside of the film exterior body, and an adhesive layer interposed between the film exterior body and the reinforcing body, the power generation element includes a sheet-like electrode group and a non-aqueous electrolyte, the sheet-like electrode group includes a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, and in a tensile test based on JIS K 7161 (2014), the tensile strength F2 of the reinforcement body is larger than the tensile strength F1 of the film exterior body.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a thin battery and an electronic device having excellent durability.

  As electronic devices become smaller, thinner and lighter, thin electronic devices that can be bent freely have been developed. Furthermore, a thin battery having flexibility that can be mounted on a thin electronic device has been developed, and uses of the thin electronic device are expanding (Patent Documents 1 and 2).

JP2013-161691A JP 2013-48042 A

  When a thin battery is folded, wrinkles may enter the film outer package. Further, when the thin battery is bent repeatedly, the stress concentrates in the vicinity of the wrinkles, and the film outer package may crack. If the film exterior body is cracked, the internal resistance rises due to the intrusion of moisture into the battery or volatilization of the electrolyte, resulting in deterioration of battery characteristics.

  In view of the above, one aspect of the present invention is interposed between a power generation element, a film exterior body that houses the power generation element, a reinforcement body that is disposed on the outer surface of the film exterior body, and the film exterior body and the reinforcement body. The power generation element includes a sheet electrode group and a non-aqueous electrolyte, the sheet electrode group includes a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, JIS K 7161 In the tensile test based on (2014), the tensile strength F2 of the reinforcing body relates to a thin battery having a larger tensile strength F1 of the film outer package.

  ADVANTAGE OF THE INVENTION According to this invention, it can suppress that a wrinkle enters into a film exterior body.

It is a top view of the thin battery which concerns on embodiment of this invention. It is a schematic sectional drawing of the XX line cross section of FIG. It is a schematic sectional drawing of the sheet-like electrode group of the thin battery which concerns on embodiment of this invention. It is a schematic sectional drawing of the film exterior body of the thin battery which concerns on embodiment of this invention. It is a plane schematic diagram which shows the positional relationship of the film exterior body, reinforcement body, and sheet-like electrode group of the thin battery which concerns on embodiment of this invention. It is a schematic sectional drawing of the electronic device which comprises the thin battery and electronic device which concern on embodiment of this invention.

  A thin battery according to the present invention includes a power generation element, a film exterior body that houses the power generation element, a reinforcing body that is disposed on the outer surface of the film exterior body, and an adhesive layer that is interposed between the film exterior body and the reinforcing body. It comprises. The power generation element includes a sheet electrode group and a non-aqueous electrolyte. The sheet electrode group includes a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode. In the tensile test based on JIS K 7161 (2014), the tensile strength F2 of the reinforcing body is larger than the tensile strength F1 of the film exterior body.

  The reinforcing body should just be distribute | arranged to the outer surface of the film exterior body, and has covered at least one part of the film exterior body. The reinforcing body does not need to cover the entire film outer package. The wrinkles of the film outer package often occur near the center of the battery. That is, for example, if the reinforcing body is disposed on the film exterior body so as to be in contact with the central portion of the main surface of the film exterior body, an effect of suppressing wrinkles from entering the film exterior body can be obtained.

  Since the film outer package has flexibility, when the thin battery is bent, it tends to cause wrinkles in the film outer package in order to relieve stress. However, when wrinkles occur in the film outer package, stress concentrates in the vicinity of the wrinkles, and cracks are likely to occur in the film outer package. Here, when the reinforcing body having a larger tensile strength than the film exterior body is disposed on the outer surface of the film exterior body, and the adhesive layer is interposed between the film exterior body and the reinforcement body, the reinforcement body presses the film exterior body, It is thought to suppress wrinkles. On the other hand, since the adhesive layer has viscosity or fluidity, it is considered that the adhesive layer functions to disperse the stress generated at the interface between the film exterior body and the reinforcement body from the main surface of the film exterior body to the periphery. That is, the pressure-sensitive adhesive layer serves as a buffer layer between the film exterior body and the reinforcing body. In this way, wrinkles that can occur in the film outer body are suppressed by the synergistic action of the adhesive layer interposed between the film outer body and the reinforcing body and the reinforcing body, and cracks in the film outer body in the vicinity of the wrinkles And can prevent damage.

  The pressure-sensitive adhesive layer preferably has both a viscosity capable of bonding the film exterior body and the reinforcement body and a fluidity capable of sufficiently relaxing the stress generated at the interface between the film exterior body and the reinforcement body. Further, the adhesive layer may be a single layer or a multilayer.

  Examples of the single adhesive layer include rubber-based, acrylic-based, silicone-based, and urethane-based materials. Examples of the rubber-based material include natural rubber, butyl rubber, ethylene propylene rubber, acrylic-based polymer as an acrylic material, silicone rubber as a silicone-based material, and urethane resin and urethane rubber as a urethane-based material.

  For example, a double-sided tape can be used as the multilayer adhesive layer. A double-sided tape has base materials, such as a film, paper, and a nonwoven fabric, and the adhesion layer formed in the both surfaces. For the adhesive layer, the same material as that of the single adhesive layer can be used.

  A resin sheet, a metal plate, or the like is used for the reinforcing body. The resin sheet may be formed of a thermoplastic resin, a cured thermosetting resin, or the like. As the thermoplastic resin, PET (polyethylene terephthalate), PA (polyamide), polyvinyl chloride, acrylic resin, PC (polycarbonate), PP (polypropylene), nylon, and the like can be used. As the thermosetting resin, an epoxy resin, a phenol resin, or the like can be used. As the metal plate, an Fe or Fe alloy plate, an Al or Al alloy plate, a Cu or Cu alloy plate, a Zn or Zn alloy plate, or the like can be used. Among them, an Fe alloy plate is preferable, and an SUS (stainless steel) plate is particularly preferable. This is because the SUS plate has high tensile strength even when the thickness is small.

The physical properties of the film exterior body and the reinforcing body will be described in more detail.
In the tensile test based on JIS K 7161 (2014), the tensile strength F1 of the film outer package is preferably 10 MPa or more and 75 MPa or less. The film outer package having a tensile strength F1 of 75 MPa or less has high flexibility. Moreover, if the tensile strength F1 of a film exterior body is 10 Mpa or more, sufficient intensity | strength to accommodate an electric power generation element can be maintained. From the viewpoint of improving flexibility, F1 is more preferably 60 MPa or less, and further preferably 50 MPa or less. From the viewpoint of obtaining a film outer package having higher mechanical strength, F1 is more preferably 15 MPa or more, and further preferably 20 MPa or more. These upper limits and lower limits can be arbitrarily combined to set the range of tensile strength.

  In the tensile test based on JIS K 7161 (2014), the tensile strength F2 of the reinforcing body is preferably 80 MPa or more, and more preferably 100 MPa or more. As a result, sufficient rigidity can be imparted to the reinforcing body, and when the thin battery is bent, it becomes more difficult for wrinkles to enter the film exterior body, and the stress generated at the interface between the electrode group and the film exterior body is efficiently dispersed. Is done. However, the reinforcing body is flexible enough to allow the thin battery to be bent. In order to allow bending of the thin battery, the tensile strength F2 of the reinforcing body may be, for example, 1000 MPa or less, and more preferably 800 MPa or less. These upper limits and lower limits can be arbitrarily combined to set the range of tensile strength.

  Ratio of the tensile strength F1 of the film outer package to the tensile strength F2 of the reinforcing body: F1 / F2 preferably satisfies F1 / F2 <0.5, and F1 / F2 <0.4 or F1 / F2 <0.3. It is further preferable to satisfy Thereby, the softness | flexibility of the whole thin battery can be improved, suppressing the wrinkle of a film exterior body and improving the dispersibility of the stress which arises in the interface of a reinforcement body and a film exterior body. The lower limit of F1 / F2 is preferably larger than 0.1, for example, considering the mechanical strength necessary for the film outer package to accommodate the power generation element.

  The thickness H1 of the film outer package is preferably 50 μm <H1 <100 μm. As a result, the thin battery is more easily bent and the film exterior body can easily maintain the required strength. From the viewpoint of further improving the flexibility of the thin battery, H1 is more preferably 90 μm or less, and further preferably 80 μm or less. Further, from the viewpoint of improving the mechanical strength of the power generation element, H1 is more preferably 60 μm or more, and further preferably 70 μm or more. These upper limits and lower limits can be arbitrarily combined to set the range of tensile strength.

  The thickness H2 of the reinforcing body is preferably 10 μm <H2 <500 μm. Thereby, it becomes easy to restrict | limit the thickness of a thin battery small. From the viewpoint of appropriately maintaining the thickness of the thin battery, H2 is more preferably 400 μm or less, and even more preferably 300 μm or less. In consideration of the strength of the thin battery, H2 is more preferably 50 μm or more, and further preferably 100 μm or more. These upper limits and lower limits can be arbitrarily combined to set the range of tensile strength.

  The ratio of the thickness H1 of the film outer package to the thickness H2 of the reinforcing body: H1 / H2 may satisfy 0.25 <H1 / H2 <3.0. This makes it easier to further improve the flexibility of the entire thin battery and to ensure the rigidity necessary for the reinforcing body. From the viewpoint of achieving both the flexibility of the thin battery and the rigidity of the reinforcing body, H1 / H2 is preferably 0.3 <H1 / H2 <2.5, and more preferably 0.5 <H1 / H2 <2.0. .

  The thickness of the thin battery is not particularly limited, but is preferably 1 mm or less, and more preferably 0.7 mm or less in consideration of flexibility and convenience of use of the electronic device (for example, a feeling of wearing on the human body).

  Hereinafter, an example of a thin battery according to an embodiment of the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiments.

  FIG. 1 is a top view of the thin battery according to the present embodiment. FIG. 2 is a schematic sectional view taken along line XX of FIG.

  As shown in FIGS. 1 and 2, a thin battery 1 includes a power generation element including a sheet-like electrode group 2 and a nonaqueous electrolyte impregnated therein, a film exterior body 3 that houses the power generation element, and a film exterior. A reinforcing body 4 is provided on the outer surface of the body 3. An adhesive layer 5 is provided between the film exterior body 3 and the reinforcing body 4. Connected to the sheet-like electrode group 2 are a positive electrode lead 9 and a negative electrode lead 10 for taking out current to the outside. Part of the positive electrode lead 9 and the negative electrode lead 10 is exposed to the outside from the film outer package 3 and the reinforcing body 4, and the exposed portions function as a positive electrode external terminal and a negative electrode external terminal.

Next, the sheet-like electrode group will be exemplarily described.
FIG. 3 is a schematic cross-sectional view of an example of a sheet-like electrode group. A sheet-like electrode group 103 shown in FIG. 3 includes a pair of negative electrodes 110 positioned on the outside, a positive electrode 120 disposed therebetween, and a separator 107 interposed between the negative electrode 110 and the positive electrode 120. The negative electrode 110 includes a negative electrode current collector sheet 111 and a negative electrode active material layer 112 attached to one surface thereof. The positive electrode 120 includes a positive electrode current collector sheet 121 and a positive electrode active material layer 122 attached to both surfaces thereof. The pair of negative electrodes 110 are arranged with the positive electrode 120 sandwiched so that the negative electrode active material layer 112 and the positive electrode active material layer 122 face each other with the separator 107 interposed therebetween.

  The separator 107 is bonded to the negative electrode active material layer 112 and the positive electrode active material layer 122. As a method of adhering the separator 107 to each active material layer, it is preferable to apply a resin that swells with a nonaqueous electrolyte to the surface of the separator 107 and / or each active material layer. As the resin swells with the non-aqueous electrolyte, a gel electrolyte is formed. The gel electrolyte functions as an adhesive.

  Note that the positive electrode active material layer 122 and the negative electrode active material layer 112 may be provided on both surfaces of the positive electrode current collector sheet 121 and the negative electrode current collector sheet 111, respectively. Further, the configuration of the sheet-like electrode group 103 is not particularly limited. For example, even in a configuration in which one positive electrode 120 is sandwiched between two negative electrodes 110, one negative electrode 110 is sandwiched between two positive electrodes 120. But you can. Further, for example, even in a configuration in which one positive electrode 120 is sandwiched between two negative electrodes 110, the configuration in which one negative electrode 110 is sandwiched between two positive electrodes 120 is a two-layer configuration. But you can.

  The positive electrode active material layer 122 is a mixture layer including a positive electrode active material, a binder, and, if necessary, a conductive agent.

  Examples of the positive electrode current collector sheet 121 include metal materials such as metal films, metal foils, and metal fiber nonwoven fabrics. Examples of the metal species used include silver, nickel, titanium, gold, platinum, aluminum, and stainless steel. These metal species may be used alone or in combination of two or more. The thickness of the positive electrode current collector sheet 121 is preferably 5 to 30 μm, and more preferably 8 to 15 μm.

The positive electrode active material is not particularly limited. For example, lithium-containing composite oxides such as Li _xa CoO ₂ , Li _xa NiO ₂ , Li _xa MnO ₂ , Li _xa Co _y Ni _1-y O ₂ , Li _xa Co _y M _1-y O ₂ , Li _xa Ni _{1-y M y O 2,} Li xb Mn 2 O 4, etc. _{Li xb Mn 2-y M y} O 4 and the like. Here, M is at least one element selected from the group consisting of Na, Mg, Sc, Y, Mn, Fe, Co, Ni, Cu, Zn, Al, Cr, Pb, Sb and B, and xa = 0 to 1.2, xb = 0 to 2, y = 0 to 0.9, and z = 2 to 2.3. xa and xb increase / decrease by charging / discharging.

  Examples of the binder include a fluorine resin containing a vinylidene fluoride unit such as polyvinylidene fluoride (PVdF), a fluorine resin not containing a vinylidene fluoride unit such as polytetrafluoroethylene, polyacrylonitrile, and polyacrylic acid. Examples thereof include rubbers such as acrylic resin and styrene butadiene rubber. The amount of the binder is, for example, 0.5 to 15 parts by mass per 100 parts by mass of the negative electrode active material.

  The thickness of the positive electrode active material layer 122 is preferably, for example, 1 to 300 μm. If the thickness of the positive electrode active material layer 122 is 1 μm or more, a sufficient capacity can be maintained. On the other hand, when the thickness of the positive electrode active material layer 122 is 300 μm or less, the flexibility of the positive electrode 120 is increased, and the bending load applied to the current collector tends to be reduced. In addition, when the positive electrode 120 is arrange | positioned at the edge part (outermost layer) of the sheet-like electrode group 103, the positive electrode active material layer 122 is formed only on the single side | surface of the positive electrode collector sheet 121 which comprises the positive electrode 120 of the edge part. Preferably, the positive electrode 120 disposed in the inner layer portion is formed on both surfaces of the positive electrode current collector sheet 121. The positive electrode 120 at the end is arranged with the surface on which the positive electrode active material layer 122 is formed facing inward.

  The material of the positive electrode lead 9 is not particularly limited as long as it is electrochemically and chemically stable and has conductivity, and may be a metal or a nonmetal. Among these, a metal foil is preferable. Examples of the metal foil include aluminum foil, aluminum alloy foil, and stainless steel foil. The thickness of the positive electrode lead 9 is preferably 25 to 200 μm, more preferably 50 to 100 μm. The positive electrode lead 9 is connected to the positive electrode current collector sheet 121 by welding.

  The negative electrode active material layer 112 is a mixture layer including a negative electrode active material, a binder, and, if necessary, a conductive agent.

  Examples of the negative electrode current collector sheet 111 include metal materials such as metal films, metal foils, and metal fiber nonwoven fabrics. The metal foil may be an electrolytic metal foil obtained by an electrolytic method or a rolled metal foil obtained by a rolling method. The electrolytic method has the advantages that it is excellent in mass productivity and relatively low in production cost. On the other hand, the rolling method is easy in thickness reduction and is advantageous in terms of weight reduction. Among these, a rolled metal foil is preferable in that it is crystallized along the rolling direction and has excellent bending resistance.

  Examples of the metal species used for the negative electrode current collector sheet 111 include copper, nickel, magnesium, and stainless steel. These metal species may be used alone or in combination of two or more. The thickness of the negative electrode current collector sheet 111 is preferably 5 to 30 μm, and more preferably 8 to 15 μm.

  The negative electrode active material layer 112 includes a negative electrode active material, and may be a mixture layer including a binder and a conductive agent as necessary. The negative electrode active material is not particularly limited, and can be appropriately selected from known materials and compositions. Examples thereof include metallic lithium, lithium alloys, carbon materials (natural and artificial graphites, etc.), silicides (silicon alloys), silicon oxides, lithium-containing titanium compounds (for example, lithium titanate), and the like.

  As the binder and the conductive agent, the materials exemplified for the positive electrode 120 can be exemplified as well. Further, the blending amounts thereof are the same as those of the positive electrode 120.

  The thickness of the negative electrode active material layer 112 is preferably, for example, 1 to 300 μm. When the thickness of the negative electrode active material layer 112 is 1 μm or more, a sufficient capacity can be maintained. On the other hand, when the thickness of the negative electrode active material layer 112 is 300 μm or less, the flexibility of the negative electrode 110 is increased, and the bending load applied to the current collector tends to be reduced. The negative electrode active material layer 112 is preferably formed only on one side of the negative electrode current collector sheet 111 for the negative electrode 110 disposed at the end (outermost layer) of the sheet-like electrode group 103, and is formed on the inner layer portion. The negative electrode 110 to be disposed is formed on both surfaces of the negative electrode current collector sheet 111. The negative electrode 110 at the end is arranged with the surface on which the negative electrode active material layer 112 is formed facing inward.

  The material of the negative electrode lead 10 is not particularly limited as long as it is electrochemically and chemically stable and has conductivity, and may be a metal or a nonmetal. Among these, a metal foil is preferable. Examples of the metal foil include copper foil, copper alloy foil, nickel foil, and stainless steel foil. The thickness of the negative electrode lead 10 is preferably 25 to 200 μm, more preferably 50 to 100 μm. The negative electrode lead 10 is connected to the negative electrode current collector sheet 111 by welding.

  The nonaqueous electrolyte is not particularly limited. For example, a dry polymer electrolyte in which an electrolyte salt is contained in a polymer matrix, a gel polymer electrolyte in which a polymer matrix is impregnated with a solvent and an electrolyte salt, an inorganic solid electrolyte, a liquid electrolyte (electrolyte) in which an electrolyte salt is dissolved in a solvent, etc. Is mentioned.

  The material used for the polymer matrix (matrix polymer) is not particularly limited, and for example, a material that gels by absorbing the liquid electrolyte can be used. Specific examples include a fluororesin containing a vinylidene fluoride unit, an acrylic resin containing a (meth) acrylic acid and / or (meth) acrylic acid ester unit, and a polyether resin containing a polyalkylene oxide unit. Examples of the fluororesin containing a vinylidene fluoride unit include PVdF, a copolymer (VdF-HFP) containing a vinylidene fluoride (VdF) unit and a hexafluoropropylene (HFP) unit, a vinylidene fluoride (VdF) unit, and trifluoro. And a copolymer (VdF-TFE) containing an ethylene (TFE) unit. The amount of the vinylidene fluoride unit contained in the fluororesin containing the vinylidene fluoride unit is preferably 1 mol% or more so that the fluororesin can easily swell in the liquid electrolyte.

Examples of the electrolyte salt include LiPF ₆ , LiClO ₄ , LiBF ₄ , LiCF ₃ SO ₃ , LiCF ₃ CO ₂ , and imide salts. Examples of the solvent include cyclic carbonates such as propylene carbonate (PC), ethylene carbonate (EC), and butylene carbonate; chain carbonates such as diethyl carbonate (DEC), ethyl methyl carbonate, and dimethyl carbonate; γ-butyrolactone, γ -Non-aqueous solvents such as cyclic carboxylic acid esters such as valerolactone; dimethoxyethane; The inorganic solid electrolyte is not particularly limited, and an inorganic material having ionic conductivity can be used.

  A separator may be included in the nonaqueous electrolyte to prevent a short circuit. The material for the separator is not particularly limited, and examples thereof include a porous sheet having a predetermined ion permeability, mechanical strength, and insulating properties. For example, a porous film or nonwoven fabric made of polyolefin such as polyethylene or polypropylene, polyamide such as polyamide or polyamideimide, or cellulose is preferable. The thickness of the separator is, for example, 8 to 30 μm.

  FIG. 4 is a schematic cross-sectional view of the film outer package 3 of the thin battery 1 according to this embodiment. As shown in FIG. 4, the film outer package 3 includes a barrier layer 11a, a first resin film (hereinafter referred to as a seal layer) 11b and a second resin film (hereinafter referred to as a protective layer) formed on both surfaces thereof. ) 11c, and a laminate film.

  Although the film exterior body 3 is not specifically limited, It is preferable to comprise a film material with low gas permeability and high flexibility. As the barrier layer 11a, metal materials such as aluminum, nickel, stainless steel, titanium, iron, platinum, gold, and silver, and inorganic materials such as silicon oxide, magnesium oxide, and aluminum oxide are used from the viewpoint of strength, gas barrier performance, and bending rigidity. It is preferable to include a material (ceramic material). From the same viewpoint, the thickness of the barrier layer 11a is preferably 5 to 50 μm, and more preferably 10 to 40 μm. The thickness of the seal layer 11b is preferably 10 to 100 μm. The protective layer 11c is preferably PA such as 6,6-nylon, polyester such as polyolefin, PET, or polybutylene terephthalate from the viewpoint of strength, impact resistance, and chemical resistance. The thickness of the protective layer 11c is preferably 5 to 100 μm.

Specifically, the film outer package 3 includes a PE / Al layer / PE laminate film, an acid-modified PP / PET / Al layer / PET laminate film, an acid-modified PE / PA / Al layer / PET laminate film, and an ionomer. Examples include a resin / Ni layer / PE / PET laminate film, an ethylene vinyl acetate / PE / Al layer / PET laminate film, and an ionomer resin / PET / Al layer / PET laminate film. Here, instead of the Al layer, an inorganic compound layer such as an Al ₂ O ₃ layer or an SiO ₂ layer may be used.

  Next, an example of a method for manufacturing the thin battery 1 will be described.

  Each electrode is arrange | positioned so that a positive electrode may be pinched | interposed into a pair of negative electrode, and a sheet-like electrode group is comprised through a separator between a negative electrode and a positive electrode. At this time, a positive electrode lead is attached to the positive electrode, and a negative electrode lead is attached to the negative electrode. On the other hand, after inserting a sheet-like electrode group from one opening of the film exterior body formed in a cylindrical shape, the opening is closed by heat welding. At this time, the electrode group is arranged so that a part of the positive electrode lead and the negative electrode lead is exposed to the outside from one opening of the cylindrical film outer package. This exposed portion becomes a positive external terminal and a negative external terminal. Next, a nonaqueous electrolyte is injected from the other opening, and the other opening is thermally welded under a reduced pressure environment. The cylindrical film outer package can be obtained, for example, by folding a laminate film of a predetermined size in two and partially welding the ends of the laminate film.

  Next, an adhesive tape is applied to the entire surface of the film outer package. An adhesive tape is not specifically limited, For example, a commercially available double-sided tape can be used.

  Next, the thin battery 1 is completed by using two reinforcing bodies and sandwiching the film exterior body to which the adhesive tape is attached.

  As a more specific configuration of the thin battery, for example, at least 80% or more of the area of the first projected image when the film outer body is viewed from the normal direction is the first when the reinforcing body is viewed from the normal direction. It is desirable to configure so as to overlap with the two projected images. By comprising in this way, a reinforcement body is pressed on the vertical direction with respect to most of the surface of a film exterior body. That is, the reinforcing body can press the film exterior body 3 against the sheet-like electrode group and suppress wrinkles.

  FIG. 5 is a schematic plan view showing the positional relationship between the film outer package 3, the reinforcing body 4, and the sheet electrode group 2 of the thin battery 1. As shown in FIG. 5, the outer edge of the reinforcing body 4 is preferably disposed in a region between the outer edge of the film outer package 3 and the outer edge of the sheet-like electrode group 2. Here, the arrow in FIG. 5 indicates a region suitable for the arrangement of the outer edge of the reinforcing body 4. By comprising in this way, the reinforcement body 4 presses the film exterior body 3 with respect to the sheet-like electrode group 2, and functions to suppress wrinkles.

The following can be considered about the mechanism in which the reinforcing body 4 suppresses wrinkles.
When the thin battery 1 is bent, stress is generated as a driving force that causes wrinkles in the film outer package 3 due to the difference between the inner and outer circumferences. On the other hand, since the reinforcing body 4 bonded to the film exterior body 3 through the adhesive layer 5 has a large rigidity, it can counter the driving force that causes wrinkles. Moreover, when the adhesive layer 5 flows, the stress that is a driving force for generating wrinkles is relieved. It is considered that wrinkles generated in the film outer package 3 can be suppressed by such a mechanism.

  Furthermore, by disposing the end of the reinforcing body 4 between the outer edge of the film exterior body 3 and the outer edge of the sheet-like electrode group 2, it becomes easier to diffuse the stress when the battery is bent around the exterior body. , It becomes easier to suppress the occurrence of wrinkles.

  Next, an electronic device according to one embodiment of the present invention includes a thin battery and an electronic device using the thin battery as a driving power source, and the reinforcing body covers at least a part of the electronic device together with the thin battery. FIG. 6 is a schematic cross-sectional view of an electronic apparatus including a thin battery and an electronic device. In the electronic device 13 shown in FIG. 6, the thin battery 1 including the sheet-like electrode group 2 housed in the film outer package 3 and the electronic device 12 using the thin battery 1 as a driving power source are integrated. Both the electronic device 12 and the thin battery 1 are covered with the reinforcing body 4 via the adhesive layer 5.

  The electronic device may include at least two thin batteries arranged side by side so as not to overlap each other in the thickness direction. The connection method of at least two thin batteries is not particularly limited, and may be connected in series or in parallel. Laminate films may be heat-welded in a region between adjacent thin batteries 1. That is, a sealed space may be provided for each thin battery.

  The thickness H2 of the reinforcing body 4 is preferably 10 μm <H2 <500 μm. Thereby, it becomes easy to restrict | limit the thickness of the electronic device 13 which covers the electronic device 12 which uses the thin battery 1 and the thin battery 1 as a drive power supply. From the viewpoint of appropriately maintaining the thickness of the thin battery 1 and the electronic device 13, H2 is more preferably 400 μm or less, and further preferably 300 μm or less. In consideration of the strength of the thin battery 1 and the electronic device 13, H2 is more preferably 50 μm or more, and further preferably 100 μm or more. These upper limits and lower limits can be arbitrarily combined to set the range of tensile strength. The thickness of the sheet-like electronic apparatus in which the thin battery 1 and the electronic device 12 are integrated is preferably 2 mm or less from the same viewpoint. However, if the thicknesses of the thin battery 1 and the electronic device 13 are both about 5 mm or less, relatively good wearability may be obtained.

  In recent years, in the medical field, as such an electronic device 13, a bio-applied device has been developed for the purpose of a doctor or the like monitoring biometric information of a patient or the like. As such a bio-applied device, for example, a bio-information measuring device that is brought into contact with the skin of a living body and constantly measures and wirelessly transmits bio-information such as blood pressure, body temperature, and pulse. Similarly, development of an iontophoresis transdermal administration device that supplies a drug into the body through a living body skin when a predetermined electric potential is applied as a biological sticking type device is also in progress.

  The bio-applied device is also referred to as a wearable portable terminal, and is used in a state of being in close contact with a living body, and therefore is required to have a degree of flexibility that does not cause discomfort even if it is in close contact with the skin for a long time. Therefore, excellent flexibility is also required for the power source for driving the bio-applied device. The thin battery 1 is useful as a power source for such a device.

EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is not limited to these Examples.
Example 1
In the following procedure, a thin battery having a pair of negative electrodes and a positive electrode sandwiched between them was produced.

(1) Positive electrode An aluminum foil having a thickness of 15 μm was prepared as a positive electrode current collector sheet. The positive electrode mixture slurry was applied to both surfaces of the aluminum foil, dried and then rolled to form a positive electrode active material layer to obtain a positive electrode sheet. The positive electrode mixture slurry is a mixture of 100 parts by mass of lithium cobalt oxide as a positive electrode active material, 1.2 parts by mass of acetylene black as a conductive agent, 1.2 parts by mass of PVdF as a binder, and an appropriate amount of NMP. Prepared. The thickness (per one surface) of the positive electrode active material layer was 37 μm. A 45 mm × 16 mm positive electrode having a 5 mm × 5 mm tab was cut out from the positive electrode sheet, and the active material layer was peeled off from the positive electrode tab to expose the aluminum foil. Thereafter, an aluminum positive electrode lead was ultrasonically welded to the tip portion of the positive electrode tab.

(2) Negative electrode An electrolytic copper foil having a thickness of 8 μm was prepared as a negative electrode current collector sheet. The negative electrode mixture slurry was applied to one surface of the electrolytic copper foil, dried and rolled to form a negative electrode active material layer, thereby obtaining a negative electrode sheet. The negative electrode mixture slurry was prepared by mixing 100 parts by mass of graphite as a negative electrode active material, 8 parts by mass of polyvinylidene fluoride (PVdF) as a binder, and an appropriate amount of N-methyl-2-pyrrolidone (NMP). Prepared. The thickness of the negative electrode active material layer was 54 μm. A negative electrode having a size of 47.5 mm × 18 mm having a negative electrode tab of 5 mm × 5 mm was cut out from the negative electrode sheet, and the active material layer was peeled off from the negative electrode tab to expose the copper foil. Then, the negative electrode lead made from nickel was ultrasonically welded to the front-end | tip part of the negative electrode tab of one negative electrode.

(3) non-aqueous electrolyte prepared ethylene carbonate (EC) and diethyl carbonate (DEC) in a mixed solvent mainly, by dissolving LiPF _6, to prepare a nonaqueous electrolyte.

(4) Production of Electrode Group The positive electrode was placed between a pair of negative electrodes through a separator so that the negative electrode active material layer and the positive electrode active material layer face each other, thereby forming an electrode group. As the separator, a microporous polyethylene film (thickness 15 μm) having a size of 49 mm × 18 mm was used.

(5) Production of film exterior body Film exterior including PE film (thickness 30 μm) to be a sealing layer, rolled aluminum foil (thickness 15 μm) to be a gas barrier layer, and PE film (thickness 30 μm) to be a protective layer A body (thickness 75 μm) was prepared. In addition, the tensile strength F1 of the film exterior body in the tensile test based on JIS K 7161 (2014) was 32 MPa.

(6) Assembly of thin battery An electrode group was arranged inside a 60.0 mm × 29.0 mm bag-shaped film outer package so that part of the positive and negative leads was exposed to the outside from the opening of the film. Next, the electrode group was housed in an exterior body made of a cylindrical laminate film having an aluminum barrier layer. Subsequently, the positive electrode lead and the negative electrode lead were led out from one opening of the film outer package, and the opening was sealed by thermal welding with each lead interposed therebetween. Next, a nonaqueous electrolyte was injected from the other opening, and the other opening was thermally welded under a reduced pressure environment of −650 mmHg.

  Next, the reinforcement body was comprised so that the outer edge of a reinforcement body might be arrange | positioned in the area | region between the outer edge of a film exterior body, and the outer edge of a sheet-like electrode group. Specifically, an adhesive tape (Nichiban Co., Ltd., Nystack, thickness of about 0.1 mm) was attached to the side of the reinforcing body facing the sheet-like electrode group. Subsequently, two PET plates having a thickness of 0.25 mm were used as reinforcing bodies, and the film exterior body to which the adhesive tape was attached was sandwiched. Thereby, a flexible thin battery A1 having a size of 60.0 mm × 29.0 mm was produced.

  The reinforcing body 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 performed using a universal testing machine at a tensile speed of 5 mm / min in accordance with JIS K7161 (2014). The tensile strength F2 of the reinforcing body was measured and found to be 200 MPa.

Example 2
A thin battery A2 was prepared in the same manner as in Example 1 except that two polyethylene (PE) plates having a thickness of 0.18 mm were used as the reinforcing body. In addition, when the tensile strength F2 of the reinforcing body was measured by the same method as in Example 1, it was 40 MPa.

Example 3
As a film outer package, a seal layer having a thickness of 15 μm, a gas barrier layer having a thickness of 6 μm, and a protective layer having a total thickness of 41 μm including 20 μm, and two reinforcing plates having a thickness of 0.18 mm are used. A thin battery A3 was produced in the same manner as in Example 1 except that it was used. In addition, it was 28 Mpa when the tensile strength F1 of the film exterior body was measured by the method similar to Example 1. FIG.

Example 4
As a film outer package, a seal layer having a thickness of 30 μm, a gas barrier layer having a thickness of 50 μm, a protective layer having a thickness of 110 μm including 30 μm, and two reinforcing plates having a thickness of 0.18 mm are used. A thin battery A4 was produced in the same manner as in Example 1 except that it was used. In addition, it was 80 Mpa when the tensile strength F1 of the film exterior body was measured by the method similar to Example 1. FIG.

<< Comparative Example 1 >>
A thin battery B1 was produced in the same manner as in Example 1 except that the reinforcing body was not used.

<< Comparative Example 2 >>
Two PE plates with a thickness of 2 mm are arranged on the two main surfaces of the film outer package, and the PE plates are bonded to each other with a frame-shaped adhesive corresponding to the total thickness of the electrode group and the film outer package. The power generation element accommodated in the film outer package was sandwiched and fixed in the gap. Thus, a thin battery B2 was produced in the same manner as in Example 1 except that the film outer package was reinforced with the PE plate without providing the adhesive layer. In addition, when the tensile strength F2 of the reinforcing body was measured by the same method as in Example 1, it was 40 MPa.

(Evaluation of battery discharge capacity maintenance rate)
About the produced thin battery (n = 5), the discharge test was implemented on condition of the following, and the discharge capacity of the battery before bending was calculated | required.
Environmental temperature: 25 ° C
Discharge current: 0.2 CmA (1C is the design capacity of thin battery)
End-of-discharge voltage: 3.0V

  A pair of expandable and contractible fixing members were horizontally arranged opposite to each other, and a battery was attached to each of the fixing members and fixed. Then, in an environment of 25 ° C., the distance between both ends of the fixing member was shortened so that the curvature radius of the battery was R25 mm, and then both ends of the fixing member were returned to the original state to return the battery to a flat state. This bending operation was repeated 10,000 times. After bending, the discharge capacity after bending was determined by conducting the above discharge test on the thin battery. Then, the capacity retention rate (%) after bending was derived from the following equation. The capacity retention rate was determined using five thin batteries before and after bending, and an average value was derived.

Capacity retention ratio after bending (%) = (discharge capacity after bending / discharge capacity before bending) × 100
Table 1 shows the configuration of each thin battery and the results of the capacity retention ratio after bending.

  From Table 1, the batteries (A1 to A4) of Examples 1 to 4 in which the tensile strength F2 of the reinforcing body is larger than the tensile strength F1 of the film outer package have good capacity retention ratios after bending. I understand that. On the other hand, in the batteries (B1, B2) of Comparative Examples 1 and 2 without the reinforcing body or the adhesive layer, the capacity retention rate after bending decreased. In the case of the battery (B1) of Comparative Example 1, since there is no reinforcing body, the film outer package is easily cracked by bending, and moisture penetrates into the battery or the electrolytic solution volatilizes. It is considered that an increase occurs, resulting in a decrease in battery characteristics. Further, in the case of the battery (B2) of Comparative Example 2, since there is no adhesive layer, a load (stress) is not absorbed between the film outer package and the reinforcing body, the film outer package is easily broken, and battery characteristics are improved. It is thought to decline.

  Regarding the batteries (A2, A3) of Examples 2 and 3, the capacity retention rate after bending was slightly lowered as compared with Example 1 (A1). In the case of A2, since the reinforcement body of A2 is softer than the reinforcement body of A1, it is considered that the effect of suppressing wrinkles generated in the film exterior body is slightly smaller than that of A1.

  In the case of A3, the tensile strength of the film outer package is 28 MPa, which is lower than the tensile strength of 32 MPa of the film outer package of A1, so it is considered that the film outer package was slightly broken. On the other hand, in the case of the battery (A4) of Example 4, it is considered that the film outer package became hard and the wrinkles of the film outer package could not be sufficiently suppressed to the level of A1.

Based on the above results, considering the fact that the concentration of stress at the interface between the electrode group of the thin battery and the exterior body is suppressed to a local area, and the formation of wrinkles in the film exterior body is considered, the following conditions are satisfied. Is more preferable.
In the tensile test based on JIS K 7161 (2014), the ratio of the tensile strength F1 of the film outer package to the tensile strength F2 of the reinforcing body: F1 / F2 is F1 / F2 <0.5.
The thickness H1 of the film outer package is 50 μm <H1 <100 μm.
The ratio of the thickness H1 of the film outer package to the thickness H2 of the reinforcing body: H1 / H2 is 0.25 <H1 / H2 <3.0.
-In the tensile test based on JISK7161 (2014), the tensile strength F1 of a film exterior body is 10 Mpa or more and 75 Mpa or less.

  The nonaqueous electrolyte secondary battery according to the present invention is suitable for use as a power source for applications that may be greatly deformed, for example, a small electronic device such as a bio-applied device or a wearable portable terminal.

1: thin battery, 2, 103: sheet electrode group, 3: film outer package, 4: reinforcing body, 5: adhesive layer, 9: positive electrode lead, 10: negative electrode lead, 11a: barrier layer, 11b: seal layer, 11c: protective layer, 12: electronic device, 13: electronic equipment, 107: separator, 110: negative electrode, 111: negative electrode current collector sheet, 112: negative electrode active material layer, 120: positive electrode, 121: positive electrode current collector sheet, 122: Positive electrode active material layer

Claims (10)

A power generation element; a film exterior body that accommodates the power generation element; a reinforcing body disposed on an outer surface of the film exterior body; and an adhesive layer interposed between the film exterior body and the reinforcement body. ,
The power generating element comprises a sheet electrode group and a non-aqueous electrolyte,
The sheet-like electrode group comprises a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode,
A thin battery in which a tensile strength F2 of the reinforcing body is larger than a tensile strength F1 of the film exterior body in a tensile test based on JIS K 7161 (2014).   2. The thin battery according to claim 1, wherein the ratio of the tensile strength F1 of the film outer package to the tensile strength F2 of the reinforcing body: F1 / F2 satisfies F1 / F2 <0.5.   The thin battery according to claim 1 or 2, wherein a thickness H1 of the film exterior body is 50 µm <H1 <100 µm.   The ratio of the thickness H1 of the said film exterior body with respect to the thickness H2 of the said reinforcement body: The thin battery of Claim 3 with which H1 / H2 satisfy | fills 0.25 <H1 / H2 <3.0.   The thin battery of any one of Claims 1-4 whose tensile strength F1 of the said film exterior body is 10 Mpa or more and 75 Mpa or less.   80% or more of the area of the first projection image when the film exterior body is viewed from the normal direction overlaps the second projection image when the reinforcement body is viewed from the normal direction. The thin battery according to any one of the above.   The thin battery according to claim 6, wherein an outer edge of the reinforcing body is disposed in a region between an outer edge of the film exterior body and an outer edge of the sheet-like electrode group.   The thin battery according to claim 1, wherein the thin battery has a thickness of 2 mm or less. The thin battery according to any one of claims 1 to 8, and an electronic device using the thin battery as a driving power source,
An electronic apparatus, wherein the reinforcing body covers at least a part of the electronic device together with the thin battery.   The electronic device according to claim 9, comprising at least two of the thin batteries arranged side by side so as not to overlap each other in the thickness direction.

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