JP2013127989A - Film outer package battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film outer package electric device capable of detecting a generation of shedding or a wrinkle of a separator in a laminate structure.SOLUTION: The film outer package battery comprises: a laminate structure 2, formed by laminating a positive electrode plate, a separator, and a negative electrode plate; and outer package films 5 and 6 which have a metal layer with a frosted surface, and encapsulate the laminate structure 2 in a state where the frosted surface of the metal layer is facing outward.

Description

  The present invention relates to a film-clad battery using a laminate film.

  In recent years, batteries as power sources for portable devices and the like are strongly required to be light and thin. Therefore, the battery exterior material can be further reduced in weight and thickness in place of conventional metal cans that are limited in weight and thickness, and can have a free shape compared to metal cans. As the exterior material, a metal thin film or a laminate film obtained by laminating a metal thin film and a heat-fusible resin film has been used.

  A typical example of a laminate film used as a battery exterior material is to laminate a heat-sealable resin film as a heat seal layer on one side of an aluminum thin film as a metal thin film and a protective film on the other side. Three-layer laminated film.

  In a film-clad battery using a laminate film as an exterior material, a battery element in which a positive electrode and a negative electrode are laminated via a separator is surrounded by a laminate film with a heat-fusible resin film facing each other, The battery element is hermetically sealed (hereinafter simply referred to as sealing) by heat-sealing the laminate film. In order to draw out the positive electrode and the negative electrode of the battery element to the outside of the laminate film, tabs are provided to protrude from the positive electrode and the negative electrode, respectively, and lead terminals are protruded from the laminate film and connected to these tabs. Moreover, as a separator, the porous film etc. which were formed using thermoplastic resins, such as polyolefin, are used.

  It is necessary to select good products from the viewpoint of quality control for lithium ion secondary batteries, which are industrial products. Insufficient gas removal and incomplete heat sealing can be cited as causes of defective products in the manufacturing process of lithium ion batteries (see Patent Document 1 and Patent Document 2). In addition, there are the following causes of defective products in the manufacturing process of the lithium ion battery. In a lithium ion battery, an electrode in which an electrode mixture containing a particulate electrode material is thinly applied to a metal foil is generally used. However, degranulation may occur in an inner layer of the electrode laminate. Lithium ion batteries are formed by sandwiching a resin separator having a thickness of 10 to several tens of microns between a positive electrode and a negative electrode. When manufacturing battery elements by an automatic machine or an operator, the separators are stacked. In some cases, the separators are stacked with wrinkles. Those that have shattered or wrinkled separators must be removed as defective products.

JP 2002-280077 A JP 2004-093208 A

  However, the occurrence of degranulation and wrinkling of the separator may occur after the stacking process in which the battery element is immersed in the electrolytic solution even if the generation in the stacking process is eliminated.

  Then, an object of this invention is to provide the film-clad electrical device which can detect the generation | occurrence | production of the grain fall and the wrinkle of a separator in a laminated structure.

  In order to achieve the above object, the film-clad electrical device of the present invention includes a laminated structure in which a positive electrode plate, a separator, and a negative electrode plate are laminated, and a metal layer having a matte surface, and the matte surface of the metal layer is disposed outside. And an exterior body film that seals the laminated structure.

  ADVANTAGE OF THE INVENTION According to this invention, the film-clad electrical device which can detect generation | occurrence | production of the grain fall in a laminated structure and the wrinkle of a separator can be provided.

It is a disassembled perspective view of an example of the film-clad battery of this invention. It is side sectional drawing of an example of the film-clad battery of this invention. It is a schematic diagram which shows the state which the degranulation generate | occur | produced. It is a schematic diagram which shows the state which the wrinkle generate | occur | produced in the separator. It is a schematic block diagram of the surface inspection apparatus of this invention.

  FIG. 1 shows an exploded perspective view of an example of the film-clad battery of this embodiment. FIG. 2 shows a side sectional view of an example of the film-clad battery of the present embodiment.

  The film-clad battery 1 includes a battery element 2 formed by alternately laminating a plurality of positive electrode current collectors 3a, a plurality of separators 7, and a plurality of negative electrode current collectors 3b, and two sheets containing the battery element 2 together with an electrolyte. Of the laminated films 5 and 6, a positive electrode lead terminal 4a connected to the positive electrode current collector 3a, and a negative electrode lead terminal 4b connected to the negative electrode current collector 3b.

  Each of the positive electrode plate 2a and the negative electrode plate 2b is configured by providing a layer of a composition containing an active material, a conductive agent, a binder, and the like (hereinafter referred to as an active material composition layer) on the surface of the current collector.

  Examples of the positive electrode active material include Li—Mn composite oxide, Li—Ni composite oxide, and Li—Co composite oxide. As a binder for the positive electrode active material, polytetrafluoroethylene, polyvinylidene fluoride, ethylene-propylene-diene polymer, or the like can be used. As the conductive agent, for example, natural or artificial graphites such as fibrous graphite, flaky graphite, and spherical graphite, conductive carbon black, and the like can be used.

  As the negative electrode active material, graphite such as spherical graphite and fibrous mesophase-based graphitized carbon, amorphous carbon, non-graphitizable carbon, and the like can be used. As the binder of the negative electrode active material, the above positive electrode active material The same binder as can be used.

  As the current collector, a foil or a perforated foil formed of a conductive metal can be used, and the thickness may be about 5 μm to 20 μm. As the material for the current collector on the positive electrode side, aluminum, stainless steel or the like having a thickness of about 10 μm to 20 μm is used, and as the material for the current collector on the negative electrode side, copper, nickel, silver having a thickness of about 5 μm to 15 μm, Stainless steel or the like is used.

  Examples of the separator 7 include a separator made of a polyethylene film, a separator made of a polypropylene film, and a separator made of a three-layer structure of polypropylene / polyethylene / polypropylene film. The thickness of the separator 7 is about 10 μm to 30 μm.

  As the laminate films 5 and 6, as long as the battery element 2 can be sealed so that the electrolytic solution does not leak, a film used for this type of film-clad battery can be used. A laminate film in which a layer and a heat-fusible resin layer are laminated is used. As this type of laminate film, for example, a film obtained by attaching a heat-fusible resin having a thickness of 3 μm to 200 μm to a metal foil having a thickness of 10 μm to 60 μm can be used. As the material of the metal foil, that is, the metal layer, Al, Ti, Ti-based alloy, Fe, stainless steel, Mg-based alloy and the like can be used. As the heat-fusible resin, that is, the heat-fusible resin layer, polypropylene, polyethylene, acid-modified products thereof, polyester such as polyphenylene sulfide, polyethylene terephthalate, polyamide, ethylene-vinyl acetate copolymer, etc. can be used. . Moreover, as a protective layer, polyester, nylon, etc. are suitable.

  About the thickness of each member mentioned above, if it falls below the illustrated range, the respective functions of the member may be impaired, and if it exceeds, the effect aimed at the present invention is to lift up the foreign matter and wrinkles inside the laminate on the surface. Is difficult to obtain.

  The manufacturing process of the film-clad battery 1 having the above configuration will be described below.

  First, the battery element 2 is produced. The positive electrode plate 2a and the negative electrode plate 2b can be manufactured according to a known method. For example, the positive electrode plate 2a is obtained by mixing and processing a positive electrode active material, a binder and a conductive agent, dispersing it in an organic solvent such as N-methylpyrrolidone, applying the paste to a current collector, and drying it. It can be obtained by pressurizing and cutting into an appropriate shape. The positive electrode plate 2a and the negative electrode plate 2b thus obtained and the separately prepared separator 7 are sequentially laminated in the order of the positive electrode plate 2a, the separator 7 and the negative electrode plate 2b. Subsequently, in the extending portion extending from the laminated region where the positive electrode plate 2a, the separator 7, and the negative electrode plate 2b are laminated, the extension of the positive electrode plate and the extending portion of the negative electrode plate are collectively superposed. The positive electrode current collector 3a and the negative electrode current collector 3b, which are relay parts, are formed by sonic welding. At the same time, connection of the positive electrode lead terminal 4a to the positive electrode current collector 3a and connection of the negative electrode lead terminal 4b to the negative electrode current collector 3b are also made by ultrasonic welding. The battery element 2 is obtained as described above.

  Next, the battery element 2 is sealed with the laminate films 5 and 6. First, the two laminate films 5 and 6 are surrounded with the battery element 2 sandwiched therebetween so that the heat-fusible resin layers face each other. Thereafter, the laminate films 5 and 6 are heated while being pressed by a thermal fusion head (not shown) at the peripheral edge of the laminate films 5 and 6, and the battery element 2 is sealed, whereby the film-clad battery 1 is manufactured. . At the time of sealing, the three sides of the laminate films 5 and 6 are first heat-sealed to form a bag shape in which one side is opened, and the remaining 1 of the laminate films 5 and 6 in the bag shape is opened. The electrolyte is injected from the side, and then the remaining one side is heat-sealed. The remaining one side is heat-sealed in a decompression chamber. After the battery element 2 is sealed with the laminate films 5 and 6 under reduced pressure, the laminate films 5 and 6 are brought into close contact with the surface of the battery element 2 by returning the pressure in the reduced pressure chamber to atmospheric pressure.

  Next, the battery element 2 is inspected for defects. In other words, the laminate film 5 is used to determine whether or not there is a problem that degranulation (a phenomenon in which the active material applied to the current collector is dropped) occurs in the stack of the battery elements 2 or the separator 7 is wrinkled. , 6 Confirm by surface inspection. Such an inspection is performed for the following reason.

  If the active material composition layer is degranulated from the positive electrode plate 2a or the negative electrode plate 2b, the degranulated portion does not contribute to charge / discharge. Further, when the separator 7 is wrinkled, the distance between the positive electrode plate 2a and the negative electrode plate 2b is widened, and the uniformity between the positive electrode plate 2a and the negative electrode plate 2b is lost. All of these are expected to adversely affect battery characteristics and lifetime. Therefore, it is necessary to remove a battery that has been crushed or wrinkled on the separator in the battery element 2 as a defective product.

  Below, the principle which can detect abnormality, such as the degranulation and separator wrinkle which generate | occur | produced in the battery element 2, by inspecting the surface of the laminate films 5 and 6 is demonstrated.

  In the present embodiment, the separator 7 is made of a polyethylene or polypropylene porous film or a composite film thereof having a total thickness of 20 μm to 30 μm. The positive electrode plate 2 a stacked on the separator 7 is used as the separator 7. An aluminum foil having a thickness of 20 μm to 100 μm formed on both sides of an aluminum foil having a thickness of 10 μm to 20 μm is used, and the negative electrode plate 2b has a thickness of 20 μm to 100 μm on a copper foil having a thickness of 5 μm to 15 μm. A negative electrode active material composition layer having a thickness formed on both sides is used. That is, the battery element 2 of this embodiment is formed by laminating thin plates that are easily deformed.

  When the active material composition layer generates degranulation 40 inside the battery element 2 having such a structure, as shown in FIG. 2, the degranulated active material accumulates on the separator 7, and the positive electrode plate 2a, the separator 7, and the negative electrode plate A local stress is applied to 2b to cause local deformation. In addition, even when the wrinkle 41 approaches the separator 7, as shown in FIG. 3, the portion where the wrinkle 41 approaches rises, and a local stress is applied to the positive electrode plate 2a, the separator 7, and the negative electrode plate 2b. , Causing deformation locally. As described above, since the positive electrode plate 2a or the negative electrode plate 2b is extremely thin and easily deformed, when the grain separation 40 or the wrinkle 41 is generated and the raised portion is generated on the separator 7, the positive electrode plate 2a and the separator 7 on which the raised portions are laminated. Then, a local stress is applied to the negative electrode plate 2b to cause local deformation. Then, the deformation of the positive electrode plate 2a, the negative electrode plate 2b, and the separator 7 successively applies stress to the other stacked positive electrode plate 2a, negative electrode plate 2b, and separator 7 and deforms them one after another. Eventually, this deformation extends to the surface of the uppermost layer or the lowermost positive electrode plate 2a or negative electrode plate 2b of the battery element 2.

  Although the laminate films 5 and 6 of the present embodiment are in close contact with the surfaces of the positive electrode plate 2a and the negative electrode plate 2b, the thicknesses of the laminate films 5 and 6 are about 260 μm or less. The shape of the plate 2 b is raised on the surfaces of the laminate films 5 and 6. That is, a deformed portion that extends to the uppermost layer or the lowermost positive electrode plate 2 a or the negative electrode plate 2 b of the battery element 2 due to the bulge generated in the laminated layer emerges as protrusions 50 on the surfaces of the laminate films 5 and 6. That is, the internal inspection of the battery element 2 in the manufacturing method of the present embodiment is made by laminating the positive electrode plate 2a, the negative electrode plate 2b, the separator 7, and the laminate films 5 and 6 that are easily deformed because the film-covered battery 1 is extremely thin. By taking advantage of the characteristic of being a thing, by detecting the protrusion 50 that floats on the surface of the laminate film 5, 6, and in some cases, the depression, abnormalities such as the occurrence of grain separation 40 and wrinkles 41 of the separator 7 inside the stack of the battery elements 2 Is detected.

  Next, FIG. 4 shows a schematic configuration diagram of a surface inspection apparatus for performing the surface inspection described above.

  The surface inspection apparatus according to the present embodiment includes an irradiation optical system 15, a detection system 16, a drive mechanism unit 17, a scanning system 18, and an arithmetic processing unit 19.

  The irradiation optical system 15 includes a light source unit 12 that emits a laser beam 32 that is inspection light, a deflecting optical member 23 and 24 such as a mirror that directs the laser beam 32 from the light source unit 12 onto the film-clad battery 1, and a laser beam 32 that covers the film. And a lens group 25 that focuses light on the surface of the battery 1.

  The detection system 16 includes light receiving detectors 26 and 27 having detection optical axes that intersect the optical axis of the laser beam 32 irradiated on the surface of the film-clad battery 1. The light receiving detector 26 receives the directly reflected light directly reflected from the laser beam 32 reflected from the battery surface. On the other hand, the light receiving detector 27 receives scattered light generated when reflected by the battery surface.

  The drive mechanism system 17 includes a battery holding unit 20 that holds the film-clad battery 1 and a drive unit 10 that drives the battery holding unit 20 linearly.

  The scanning system 18 reciprocally scans the irradiation optical system 15 in a direction crossing the driving direction of the film-clad battery 1 by the driving mechanism unit 17.

  The arithmetic processing unit 19 performs drive control of the irradiation optical system 15, the drive mechanism unit 17, and the scanning system 18 in addition to processing of the signal transmitted from the detection system 16.

  Next, the surface inspection process in the manufacturing method of the film-clad battery of this embodiment using the said surface inspection apparatus is demonstrated.

  The film-clad battery 1 sealed under reduced pressure is held by the battery holding unit 20. Next, the driving unit 10 is driven, and the film-clad battery 1 is conveyed to an irradiation region where the laser beam 32 emitted from the irradiation optical system 15 can be irradiated. When the film-clad battery 1 is transported to the irradiation region, the driving unit 10 feeds the film-clad battery 1 linearly and stepwise at a predetermined pitch. A laser beam 32 is emitted to the film-covered battery 1 from the irradiation optical system 15 that is reciprocally scanned in a direction orthogonal to the conveyance direction of the film-covered battery 1. The laser beam 32 applied to the laminate films 5 and 6 that are the exterior bodies of the film-clad battery 1 is reflected by the surfaces of the laminate films 5 and 6 and received by the detection system 16. When there are no protrusions 50 on the surfaces of the laminate films 5 and 6, the laser beam 32 reflected by the surfaces of the laminate films 5 and 6 is received by the light receiving detector 26. On the other hand, when the protrusions 50 are raised on the surfaces of the laminate films 5 and 6, a part of the laser beam 32 is scattered by the protrusions 50. That is, the laser beam 32 reflected by the protrusion 50 is directly reflected by the light receiving detector 26 and part of the scattered light is received by the light receiving detector 27.

  The arithmetic processing unit 19 processes the signal transmitted from the light receiving detector 27, and determines that the protrusion 50 is formed on the surfaces of the laminate films 5 and 6 when the amount of scattered light received exceeds a predetermined threshold value. To do. Further, the arithmetic processing unit 19 determines that a defect such as sag 40 or wrinkles 41 of the separator 7 has occurred in the battery element 2, and determines that the film-covered battery 1 is a defective product.

  It should be noted that the amount of scattered light that exceeds a predetermined threshold may be targeted for the one generated by one protrusion 50 or may be the total amount from a plurality of protrusions 50. Good. In other words, when a large protrusion 50 is detected, it is recognized as a defective product, and when a plurality of small protrusions 50 are detected, it may be recognized as a defective product.

  Moreover, although the example which detects the processus | protrusion 50 on the surface of the laminate films 5 and 6 using the laser beam was shown in the said embodiment, the detection method of a processus | protrusion is not limited to this. For example, light other than the laser beam may be used as the light for detecting the protrusion. In this case, the main surface of the laminate films 5 and 6 is irradiated with light from a direction other than the normal direction of the main surfaces of the laminate films 5 and 6, and the observation determination device is irradiated with the light. An abnormality may be determined based on the result of observing at least a part.

  Here, the main surface of the laminate films 5 and 6 particularly refers to the surface of the laminate films 5 and 6 in the portion in which the battery element 2 is accommodated. In addition, the normal direction of the main surface of the laminate films 5 and 6 means a normal line on the surface of the laminate films 5 and 6 in a portion in which the battery element 2 is accommodated. Moreover, directions other than the normal direction of the main surface of the laminate films 5 and 6 which are the light irradiation directions mean a direction oblique to the main surface or a direction parallel to the main surface. The observation determination apparatus may include an optical camera and an image information processing unit that processes image information of an image captured by the optical camera.

  When the laminate films 5 and 6 on which the protrusions 50 are formed are irradiated with light from the above direction, a shadow is formed by the protrusions 50. The shadow is picked up by an optical camera, and the image information processing unit detects a darker portion, that is, a shadow, than the flat portions of the laminate films 5 and 6. When the image information processing unit detects a shadow, the projections 50 are formed on the surfaces of the laminate films 5 and 6, that is, abnormalities such as the occurrence of sag 40 in the stack of battery elements 2 and wrinkles 41 in the separator 7 occur. Judge that you are doing.

  Further, as a surface observation method, the main surfaces of the laminate films 5 and 6 are irradiated with light having a periodic pattern such as a striped pattern or a lattice pattern, and the reflected light is observed through a slit having a periodic pattern. A so-called moire topography method for detecting irregularities on the surfaces of the laminate films 5 and 6 may also be used. Also in this case, the presence or absence of unevenness may be determined by performing image information processing of the captured image by the optical camera, or may be determined visually.

  In the present invention, when surface observation is performed by irradiating the main surface with light, the surface facing the outside of the metal layer of the laminate film is preferably a matte surface. An aluminum foil often used for a metal layer of a laminate film often has a glossy surface (or mirror surface) on one surface and a matte surface on the other surface. When the glossy surface is directed outward, the surrounding scenery is reflected like a mirror, making it difficult to distinguish the protrusion 50 on the surface. On the other hand, by making the matte surface face outward, the reflection of the scenery is prevented, and if it is a flat surface, uniform scattered light can be reflected, and the shadow by the protrusion 50 can be easily caught by an optical camera or visual observation. . Therefore, the surface facing the outside of the metal layer is preferably a matte surface in order to increase the accuracy of surface observation.

  In addition, when inspecting the surface of the laminate film by irradiating other than the laser beam as described above, the entire main surface is irradiated with light, and the main surface in a state where the entire surface is irradiated with light is collectively collected. It is preferable to observe. Thereby, throughput can be improved.

  Further, as a method for detecting the protrusion 50, a method other than an optical method may be used. For example, the probe or roller is scanned on the surface of the laminate films 5 and 6, and the probe or roller is displaced when the protrusion is scanned. The protrusion may be detected by detecting the amount.

DESCRIPTION OF SYMBOLS 1 Film exterior battery 2 Battery element 2a Positive electrode plate 2b Negative electrode plate 3a Positive electrode current collection part 3b Negative electrode current collection part 4a Positive electrode lead terminal 4b Negative electrode lead terminal 5, 6 Laminate film 7 Separator 10 Drive part 12 Light source part 15 Irradiation optical system 16 Detection System 17 Drive mechanism section 18 Scanning system 19 Arithmetic processing section 20 Battery holding section 23, 24 Deflection optical member 25 Lens group 26, 27 Light receiving detector 32 Laser beam 40 Shattering 41 Wrinkle 50 Projection

Claims (10)

A laminated structure in which a positive electrode plate, a separator, and a negative electrode plate are laminated;
An exterior body film comprising a metal layer having a matte surface, and sealing the laminated structure with the matte surface of the metal layer facing outward;
A film-clad electrical device.   The film-clad electrical device according to claim 1, wherein the laminated structure is sealed with the outer package film under reduced pressure.   The film-clad electrical device according to claim 1 or 2, wherein each of the positive electrode plate and the negative electrode plate has a current collector and an active material composition layer provided on a surface of the current collector. The current collector of the positive electrode plate is formed of aluminum or stainless steel;
An active material in which the active material composition layer of the positive electrode plate is any one of a Li-Mn composite oxide, a Li-Ni composite oxide, and a Li-Co composite oxide, polytetrafluoroethylene, The film-covered electrical device according to claim 3, comprising a binder that is one of polyvinylidene fluoride and an ethylene-propylene-diene-based polymer, and a conductive agent that is graphite or conductive carbon black. The current collector of the negative electrode plate is formed of any one of copper, nickel, silver, and stainless steel,
An active material in which the active material composition layer of the negative electrode plate is any one of graphite, amorphous carbon, and non-graphitizable carbon, and polytetrafluoroethylene, polyvinylidene fluoride, and an ethylene-propylene-diene polymer. 5. The film-clad electrical device according to claim 3, comprising a binder that is any of the above and a conductive agent that is graphite or conductive carbon black. In the positive electrode plate, the current collector has a thickness of 20 μm or less, and the active material composition layer has a thickness of 100 μm or less.
6. The film-covered electrical device according to claim 3, wherein the negative electrode plate has a thickness of 15 μm or less and the active material composition layer has a thickness of 100 μm or less.   The film-clad electrical device according to any one of claims 1 to 6, wherein the separator is formed of any one of a three-layer structure of a polyethylene film, a polypropylene film, and a polypropylene / polyethylene / polypropylene film.   The film-covered electrical device according to claim 1, wherein the separator has a thickness of 30 μm or less.   The exterior body film is made of any one of Al, Ti, Ti-based alloy, Fe, stainless steel, and Mg-based alloy, polypropylene, polypropylene acid-modified product, polyethylene, polyethylene acid-modified product, A film-covered electrical device according to any one of claims 1 to 8, comprising a heat-fusible resin layer formed of any one of polyphenylene sulfide, polyester, polyamide, and ethylene-vinyl acetate copolymer. .   The film-clad electrical device according to claim 1, wherein the outer package film has a thickness of 260 μm or less.

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