JP2011129446A - Laminated type battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated type battery capable of securing safety, as a specific site is preferentially opened at abnormal rise of internal pressure. <P>SOLUTION: In the laminated type battery housing an electrode body having a sheet-shape cathode, a sheet-shape anode and a separator in a laminated film outer package body structured of a metal laminate film at least laminating a metallic layer and a thermal fusion resin layer, at a thermally sealed part at a part where a cathode outer terminal and an anode outer terminal are drawn outside out of a peripheral edge part of the laminated film outer package body, a part protruded further inward into the battery than at other parts exists, and at a part further protruded inward into the battery than the other parts, a part penetrating from one side to the other is provided in the metallic layer of at least one of the metal laminated films superposed, with a part protruded further inward into the battery than the other parts to be a bent part. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a laminated battery having good safety when an internal pressure abnormally increases.

  In recent years, as the use of batteries has expanded, development aimed at improving battery characteristics such as higher capacity, higher energy density, and higher output has been actively conducted. In particular, the application of a battery to an application requiring high output and high capacity such as an automobile application has been required. For example, application of a lithium ion secondary battery has been studied.

  In many cases, a laminate film exterior body composed of a metal laminate film is used as an exterior body of a battery applied to such applications because of its advantage of being highly lightweight and lightweight.

  By the way, in a battery having a cylindrical or rectangular metal container (battery can) as an exterior body, for example, a part of the metal container is thinned to ensure safety when the battery internal pressure rises abnormally. In general, a vent portion is provided.

  On the other hand, the laminate type battery using the laminate film outer package has a smaller strength than the cylindrical or square metal container (battery can) and the heat fusion resin of the metal laminate film. Is sealed by heat sealing, so that the pressure resistance is lower than that of a battery having a metal container, and the battery expands or opens with a slight increase in internal pressure. For this reason, there has been an idea that in the laminated battery, it is not particularly necessary to install a vent portion.

  However, in recent devices, in order to manage charge and discharge and to ensure safety, there are increasing opportunities to install precise circuits near the battery, and if the electrolyte inside the battery adheres to these circuits or substrates, Corrosion may lead to equipment malfunction or fire. For this reason, even in laminated batteries, it is necessary to provide a vent so that even if liquid leaks or gas leaks from the inside, a circuit or substrate placed in the vicinity of the battery does not exist. It has become. Particularly in recent batteries, the amount of each power generation element has been increased with the increase in capacity, and in order to cope with applications requiring high load characteristics, the liquid electrolyte solution is not gelled. The need for venting is increasing because it is also being used.

  Conventionally, many techniques for providing a vent in a laminated battery have been proposed. For example, a method has been proposed in which a part of the heat seal portion of the laminate film exterior body has an end portion on the battery inner side with respect to other portions, a through hole is provided in the portion, and this portion functions as a vent. (Patent Document 1).

JP 2007-220409 A

  However, in the technique described in Patent Document 1, it is necessary to make the seal width of the heat seal portion at a location functioning as a vent wider than other portions, and the internal volume of the battery becomes small. This is disadvantageous.

  For this reason, in laminated batteries, it is required to develop a technology that can open only a specific part when the internal pressure of the battery rises abnormally while suppressing the decrease in the internal volume of the battery as much as possible. .

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a laminated battery in which a specific portion is preferentially opened to ensure safety when the internal pressure rises abnormally.

  The laminate-type battery of the present invention that has achieved the above object comprises a metal laminate film in which at least a metal layer and a heat-sealing resin layer are laminated, and has a polygonal laminate film outer package in a plan view. A laminated battery containing an electrode body having a sheet-like positive electrode connected to a positive electrode external terminal, a sheet-like negative electrode connected to a negative electrode external terminal, and a separator inside the film outer package, the laminate film outer package Is constituted by two metal laminate films or is formed by folding one metal laminate film in half, and the positive electrode external terminal and the negative electrode external terminal are peripheral portions of the laminate film outer package. The outer periphery of the laminate film exterior body is heat-sealed in a state of being pulled out from the same side. In the heat seal portion on the side where the positive electrode external terminal and the negative electrode external terminal are drawn out of the peripheral edge portion of the laminate film exterior body, it protrudes to the inner side of the battery than other portions. The portion that exists and protrudes inward of the battery with respect to the other portion is provided with a portion that penetrates from one side to the other side of the metal layer of at least one of the laminated metal laminate films. In addition, a portion that protrudes inward of the battery relative to the other portion is a vent portion.

  ADVANTAGE OF THE INVENTION According to this invention, when an internal pressure rises abnormally, a specific location can open | release preferentially and the laminated battery which can ensure safety | security can be provided.

1 is a perspective view schematically illustrating an example of a laminated battery of the present invention. It is the top view to which the principal part of the laminated battery of FIG. 1 was expanded. It is a principal part enlarged view of the AA line cross section of FIG. It is the plane schematic diagram which expanded the principal part of the other example of the laminated battery of this invention. It is the plane schematic diagram which expanded the principal part of the other example of the laminated battery of this invention.

  FIG. 1, FIG. 2 and FIG. 3 schematically show an example of a laminated battery of the present invention. 1 is a perspective view of a laminated battery 1, FIG. 2 is an enlarged plan view of a main part of the battery of FIG. 1, and FIG. 3 is an enlarged main part of the cross section along line AA of FIG.

  In the laminated battery 1, a laminated electrode body in which a plurality of sheet-like positive electrodes 20 and a plurality of sheet-like negative electrodes 30 are laminated via a separator 80, and an electrolyte solution (not shown) are polygonal (see FIG. 1). Then, the rectangular film having a curved corner) is accommodated in the laminate film outer package 40. The positive electrode external terminal 21 and the negative electrode external terminal 31 are drawn out from the same side of the peripheral edge of the laminate film outer package 40. The positive electrode external terminal 21 and the negative electrode external terminal 31 are both planar, and are connected to the sheet-like positive electrode 20 and the sheet-like negative electrode 30 directly or via a lead body in the laminate film outer package 40, respectively.

  The laminate film exterior body 40 is configured by metal laminate films 41 and 41 having a heat-sealing resin layer on the surface that is the inside of the battery. More specifically, the metal laminate films 41 and 41 related to the laminate film exterior body 40 are configured, for example, by laminating an exterior resin layer, a metal layer, and a heat fusion resin layer in order from the outside of the battery. In the heat seal portion 50 (indicated by a lattice pattern in FIGS. 1 and 2), the heat-sealing resin layer according to the upper metal laminate film 41 and the heat-sealing resin layer according to the lower metal laminate film 41 are provided. The laminated film outer package 40 is hermetically sealed by heat sealing.

  In the battery shown in FIGS. 1, 2, and 3, the heat seal portion 50 a on the side where the positive electrode external terminal 21 and the negative electrode external terminal 31 are drawn out of the peripheral edge portion of the laminate film outer package 40, A portion 50b that protrudes inward of the battery from the portion (inner side of the battery in plan view) is provided, and the metal layer of at least one of the laminated metal laminate films 41 and 41 is provided on the portion 50b from one side. A portion 60 penetrating to the other surface is formed, and the portion 50b is used as a vent portion.

  When the internal pressure of the laminated battery 10 rises, the stress caused thereby is applied to the battery inner side end portion of the heat seal portion 50 according to the laminate film outer package 40. As shown in FIGS. If the portion 50a is provided with a portion 50b that protrudes inward of the battery relative to other portions, stress concentrates on the end portion of the portion 50b on the inner side of the battery. And the said part 50b is provided with the said penetration part 60, and the intensity | strength of the metal layer part in the formation location of this penetration part 60 is made smaller than other places. Therefore, when the internal pressure of the laminate-type battery 10 is abnormally increased, the stress 60 concentrated on the portion 50b causes the breakage of the low-strength heat-sealing resin layer to cause the portion 60 penetrating through before the other portion. The portion 50b functions as a vent portion because it occurs in the vicinity of the formed portion and the internal pressure is preferentially released from the portion.

  In addition, if the part 50b which protrudes in the battery inner side rather than another part is formed in the heat seal part 50a, since the heat seal width | variety of this part will become wide, the battery internal volume which can accommodate an electrode group will reduce. However, in the battery 10 of the present invention, the portion where the portion 50b is formed is the heat seal portion 50a on the side where the positive electrode external terminal 21 and the negative electrode external terminal 31 are drawn out of the heat seal portion 50 according to the laminate film outer package 40. Thus, effective use of the internal volume of the battery is made possible, and for example, a decrease in battery capacity that may be caused by forming the portion 50b is suppressed.

  That is, in the place where the positive electrode external terminal and the negative electrode external terminal are pulled out inside the laminate film outer package of the laminate type battery, as shown in FIG. 3, there is a certain amount of space to connect these external terminals to the positive electrode and the negative electrode. Necessary. Therefore, in the battery of the present invention, the internal volume of the battery can be effectively used by providing the portion 50b in the region where the electrode group cannot be arranged in this way.

  Of the heat seal portion 50 according to the laminate film outer package 40, a portion 50b that is formed on the heat seal portion 50a on the side where the positive electrode external terminal 21 and the negative electrode external terminal are drawn out and protrudes inward of the battery from other portions. In FIG. 2, the shape of the region (indicated by hatching in FIG. 2) that is heat-sealed on the inner side of the battery with respect to the other parts is not particularly limited. Any shape such as a triangle with one apex on the inner side of the battery, a polygon such as a quadrangle (including a shape with a curved corner), or a semi-circular shape may be used, but the vent operates more stably. From the viewpoint of achieving this, it is preferably a polygon (especially a polygon whose corners are not curved), and particularly preferably a triangle having one apex on the inner side of the battery.

  Further, from the viewpoint of operating the vent portion more stably, the heat seal portion 50a on the side from which the positive electrode external terminal 21 and the negative electrode external terminal are drawn out relates to the portion 50b protruding to the inner side of the battery from other portions. The heat seal width from the end portion on the battery inner side to the outer edge of the laminate film outer package 40 (hereinafter referred to as “the seal width of the portion 50b”) and the end portion on the battery inner side of the other portion to the laminate film outer package The difference H (H in FIG. 2) from the heat seal width to the outer edge of the body 40 (W in FIG. 2; hereinafter referred to as “the seal width of other portions”) is preferably 3 mm or more, and 8 mm or more. It is more preferable that However, if the heat seal width of the portion 50b is too large, the effect of suppressing the decrease in the battery internal volume may be reduced. Therefore, the difference between the seal width of the portion 50b and the seal width W of the other portions. H is preferably 15 mm or less.

  Further, in the heat seal portion 50a on the side from which the positive electrode external terminal 21 and the negative electrode external terminal 31 are drawn out, the portion 50b that protrudes inward of the battery relative to the other portion is closer to the battery inner side than the other portion. When the heat-sealed region is a triangle having one apex on the inner side of the battery in plan view, two sides that partition the heat-sealed region starting from the apex on the inner side of the battery in the triangle The inner angle (α in FIG. 2) is preferably 20 to 170 °, and by doing so, the operational stability of the vent portion can be further enhanced.

  The penetrating portion 60 formed in the portion 50b that protrudes inward of the battery relative to the other portion in the heat seal portion 50a on the side from which the positive electrode external terminal 21 and the negative electrode external terminal are drawn out is formed in the laminate film outer package 40. Of the laminated metal laminate films 41 and 41, the metal layer may be provided on one of the metal laminate films, or may be provided on the metal layers of both metal laminate films. For example, from the viewpoint of further improving the operational stability of the vent portion or lowering the operating pressure, a portion 60 penetrating through both metal layers of the laminated metal laminate films 41 and 41 related to the laminate film outer package 40. It is preferable to reduce the strength of the portion where this is formed.

  On the other hand, when the penetrating portion 60 is formed, the battery characteristics may be deteriorated when the battery is stored for a long period of time due to intrusion of moisture in the outside air into the battery or evaporation of the electrolyte solvent. However, in order to avoid such a problem, it is preferable to form a penetrating portion 60 in any one of the metal laminate films 41 and 41 superimposed on the laminate film outer package 40. . That is, a portion penetrating the entire film is formed in advance in a portion of the metal laminate film 41 constituting the laminate film outer package 40 where the portion 50b is planned to be used, and the metal laminate film 41 is used. By manufacturing the laminate type battery, it is considered that a part of the heat-sealing resin melted at the time of heat sealing the laminate film outer package 40 enters the penetrating portion 60, thereby opening the penetrating portion 60. Is blocked, so that intrusion of moisture and evaporation of the electrolyte solvent are suppressed. Therefore, this makes it possible to improve the reliability of the laminated battery.

  The shape of the penetrating portion 60 formed in the portion 50b of the laminate film outer package 40 is not particularly limited. For example, in a plan view, the shape is straight (straight grooves or streaks) or substantially circular (true Examples thereof include a circular shape and an elliptical shape, a substantially triangular shape (including a triangular shape), and a substantially rectangular shape (including a rectangular shape).

  4 and 5 are enlarged plan views of the main part of the laminated battery 10 in which the penetrating portions 60 having various shapes are formed (in FIG. 4 and FIG. 5, lattice patterns representing heat seal portions are shown. Omitted). 4A shows an example in which the penetrating portion 60 has a streak shape, FIG. 4B shows an example in which the penetrating portion 60 has a groove shape, and FIG. 5A shows a circular shape in which the penetrating portion 60 has a circular shape. (B) is an example in which the penetrating portion 60 is triangular, and (c) is an example in which the penetrating portion 60 is square.

  A battery inner side end portion of the penetrating portion 60 in the heat seal portion 50a on the side where the positive electrode external terminal 21 and the negative electrode external terminal 31 related to the laminate film exterior body 40 are drawn to the outside, and the laminate film exterior body 40 The shortest distance in plan view between the outer edge side of the heat seal portion is L (L in FIGS. 2, 4 and 5) (mm), and the heat seal of the other portion in the heat seal portion 50a When the width is W (W in FIGS. 2, 4 and 5) (mm), it is preferable to adjust so that L> W. Also by this, the operational stability of the vent part can be enhanced.

  Note that the operating pressure of the vent portion (pressure at which the vent portion opens) can also be adjusted by adjusting the difference between L and W. That is, the larger the difference between L and W, the lower the operating pressure of the vent portion (the vent portion can be operated at a lower battery internal pressure), and the smaller the difference (the difference is a negative value). And the operating pressure of the vent portion can be increased (the vent portion can be operated at a higher battery internal pressure).

  Further, the penetrating portion 60 in the heat seal portion 50a on the side where the positive electrode external terminal 21 and the negative electrode external terminal 31 related to the laminate film outer package 40 are drawn to the outside, and the inner side of the battery than the other portions. If the shortest distance B (B in FIG. 2, FIG. 4 and FIG. 5) from the end of the protruding portion 50b is too small, the heat seal strength at the portion 50b becomes too small, and the reliability of the battery decreases. Since there exists a possibility, it is preferable that it is 2 mm or more, and it is more preferable that it is 3 mm or more.

  The preferable upper limit value of B varies depending on, for example, the shape of the penetrating portion 60, but is preferably set in a range where the relationship between L and W satisfies L> W.

  Furthermore, the formation position of the penetrating part 60 is a position where B is recognized at at least two places (the shortest distance of the same length between the penetrating part 60 and the end of the part 50b is at least two places). It is preferable. In this case, since the penetrating portion 60 is disposed at the center of the portion 50b, the heat seal strength of the portion 50b can be easily adjusted.

  In the battery of the present invention, an adhesive containing the same type of resin as the heat-sealing resin contained in the heat-sealing resin layer between the positive electrode external terminal and the negative electrode external terminal and the heat-sealing resin layer of the laminate film outer package. A positive electrode external terminal or a negative electrode external terminal and the laminate film outer package (its heat-sealing resin layer) can be bonded via this adhesive layer. The side where the positive external terminal and the negative external terminal are pulled out usually tends to reduce the strength of the heat seal part, but the heat seal part of the side where the positive external terminal and the negative external terminal are pulled out by such a method is used. Strength can be increased.

  The width of the heat seal portion at the peripheral edge of the laminate film outer package is preferably 5 to 20 mm.

  In the sheet-like positive electrode constituting the laminate battery, for example, a layer made of a positive electrode mixture containing a positive electrode active material, a conductive additive and a binder (positive electrode mixture layer) is formed on one side or both sides of the current collector. Things can be used.

As the positive electrode active material, for example, when the laminate type battery of the present invention is a lithium ion secondary battery, an active material capable of inserting and extracting lithium ions is used. As a specific example of such a positive electrode active material, for example, a layered structure represented by Li _{1 + x} MO ₂ (−0.1 <x <0.1, M: Co, Ni, Mn, Al, Mg, etc.) Lithium-containing transition metal oxide, LiMn ₂ O ₄ and spinel-structured lithium manganese oxide obtained by substituting some of its elements with other elements, LiMPO ₄ (M: Co, Ni, Mn, Fe, etc.) Type compounds. Specific examples of the lithium-containing transition metal oxide having a layered structure include LiCoO ₂ and LiNi _1-x Co _xy Al _y O ₂ (0.1 ≦ x ≦ 0.3, 0.01 ≦ y ≦ 0. 2) and other oxides containing at least Co, Ni and Mn (LiMn _1/3 Ni _1/3 Co _1/3 O ₂ , LiMn _5/12 Ni _5/12 Co _1/6 O ₂ , LiNi _{3 / 5} Mn _1/5 Co _1/5 O ₂ etc.).

  As the current collector for the positive electrode, an aluminum foil or an aluminum alloy foil is suitable. The thickness of the current collector is preferably 0.01 to 0.02 mm, for example, although it depends on the size and capacity of the battery.

  In producing the positive electrode, the positive electrode active material, a conductive additive such as graphite, acetylene black, carbon black, and fibrous carbon, and a positive electrode mixture containing a binder such as polyvinylidene fluoride (PVDF), N -A paste-like or slurry-like composition uniformly dispersed using a solvent such as methyl-2-pyrrolidone (NMP) is prepared (the binder may be dissolved in the solvent), and this composition is used as the positive electrode A method of applying to the current collector and drying, and adjusting the thickness and density of the positive electrode mixture layer by pressing as necessary can be employed. However, the manufacturing method of the positive electrode according to the present invention is not limited to the above method, and other methods may be adopted.

  The thickness of the positive electrode mixture layer in the sheet-like positive electrode is preferably 30 to 100 μm per side. Moreover, it is preferable that content of each structural component in a positive mix layer shall be positive electrode active material: 90-98 mass%, conductive support agent: 1-5 mass%, and binder: 1-5 mass%.

  The positive electrode external terminal is preferably made of aluminum or an aluminum alloy from the viewpoint of ease of connection with the equipment used. The thickness of the positive external terminal is preferably 50 to 300 μm. That is, by setting the thickness of the positive external terminal to 50 μm or more, it is possible to prevent cutting during welding of the positive external terminal and to prevent tearing due to pulling and bending. In addition, by setting the thickness of the positive external terminal to 300 μm or less, it is possible to prevent a gap in the thickness direction from being generated in the heat seal portion of the laminate film exterior body. As described above, an adhesive layer is provided between the laminate film exterior body and the positive electrode external terminal in order to increase the strength of the heat seal portion on the side where the positive electrode external terminal is drawn out of the peripheral edge portion of the laminate film exterior body. Although it can interpose, you may provide the said contact bonding layer previously in the location planned to be located in the heat seal part in a positive electrode external terminal.

  The sheet-like positive electrode and the positive electrode external terminal may be connected by directly connecting the sheet-like positive electrode current collector and the positive electrode external terminal. For example, the sheet-like positive electrode collector may be connected via an aluminum lead body. It can also be performed by connecting the electric body and the positive external terminal. The thickness of the aluminum lead body is preferably 50 to 300 μm, like the positive external terminal. Such a lead body is preferably used when the aluminum foil as the positive electrode current collector is particularly thin and the strength is insufficient for direct connection with the positive electrode external terminal.

  Examples of the method of connecting the current collector in the sheet-like positive electrode or the aluminum lead connected to the current collector and the positive external terminal include, for example, resistance welding, ultrasonic welding, laser welding, caulking, and conductive adhesive Various methods can be employed, such as the method by, but ultrasonic welding is particularly suitable.

As the sheet-like negative electrode constituting the laminated battery, for example, when the laminated battery of the present invention is a lithium ion secondary battery, one containing an active material capable of inserting and extracting lithium ions is used. Examples of such negative electrode active materials include graphite, pyrolytic carbons, cokes, glassy carbons, organic polymer compound fired bodies, mesocarbon microbeads (MCMB), and carbon fibers. One or a mixture of two or more releasable carbon-based materials is used. In addition, elements such as Si, Sn, Ge, Bi, Sb, In and their alloys, lithium-containing nitrides, or compounds that can be charged and discharged at a low voltage close to lithium metals such as oxides (such as LiTi ₅ O ₁₂ ), or Lithium metal or lithium / aluminum alloy can also be used as the negative electrode active material. Conductive aids (carbon materials exemplified as the conductive aid related to the positive electrode) and binders (mixed binders of rubber binders such as PVDF and styrene butadiene rubber (SBR)) and carboxymethyl cellulose (CMC) Etc.] or the like, and a finished product (negative electrode mixture layer) using the current collector as a core material, or the above-mentioned various alloys and lithium metal foils are laminated on the surface of the current collector And the like are used as a sheet-like negative electrode.

  For example, in the case of a sheet-like negative electrode having a negative electrode mixture layer, a negative electrode mixture containing the negative electrode active material, the binder, and a conductive auxiliary agent such as graphite, acetylene black, and carbon black, if necessary, A paste-like or slurry-like composition uniformly dispersed using a solvent such as NMP is prepared (the binder may be dissolved in the solvent), and this composition is applied onto the negative electrode current collector. The method of drying and adjusting the thickness and density of a negative mix layer layer by press processing as needed can be employ | adopted. However, the method for producing the sheet-like negative electrode according to the present invention is not limited to the above method, and other methods may be adopted.

  As the current collector for the negative electrode, a copper foil is suitable. The thickness of the current collector is preferably 0.05 to 0.02 mm, for example, although it depends on the size and capacity of the battery.

  The thickness of the negative electrode mixture layer in the sheet-like negative electrode is preferably 30 to 100 μm per side. Moreover, it is preferable that content of each structural component in a negative mix layer shall be negative electrode active material: 90-98 mass%, binder: 1-5 mass%. Moreover, when using a conductive support agent for a negative electrode, it is preferable that content of the conductive support agent in a negative mix layer shall be 1-5 mass%.

  For the negative electrode external terminal, a metal foil or ribbon such as nickel, nickel-plated copper, or nickel-copper clad is preferable. Further, the thickness of the negative electrode external terminal is preferably 50 to 300 μm similarly to the positive electrode external terminal. That is, by setting the thickness of the negative electrode external terminal to 50 μm or more, it is possible to prevent cutting during welding of the negative electrode external terminal and to prevent tearing due to pulling and bending. In addition, by setting the thickness of the negative electrode external terminal to 300 μm or less, it is possible to prevent a gap in the thickness direction from being generated in the heat seal portion of the laminate film exterior body. As described above, an adhesive layer is provided between the laminate film exterior body and the negative electrode external terminal in order to increase the strength of the heat seal portion on the side where the negative electrode external terminal is drawn out of the peripheral edge portion of the laminate film exterior body. Although it can interpose, you may provide the said adhesive layer previously in the location planned to be located in the heat seal part in a negative electrode external terminal.

  The sheet-like negative electrode and the negative electrode external terminal may be connected by directly connecting the sheet-like negative electrode current collector and the negative electrode external terminal. For example, the sheet-like negative electrode current collector may be connected via a copper lead. It can also be performed by connecting the body and the negative electrode external terminal. The thickness of the copper lead body is preferably 50 to 300 μm, similarly to the negative electrode external terminal. Such a lead body is preferably used when the copper foil as the negative electrode current collector is particularly thin and the strength is insufficient for direct connection with the negative electrode external terminal.

  Examples of the method of connecting the current collector in the sheet-like negative electrode or the copper lead connected to the current collector include various methods such as resistance welding, ultrasonic welding, laser welding, caulking, and a method using a conductive adhesive. Although methods can be employed, ultrasonic welding is particularly suitable.

  In the laminated battery of the present invention, the sheet-like positive electrode and the sheet-like negative electrode are laminated with a separator interposed therebetween, or a winding wound in a spiral shape after being overlapped with a separator. It can be used as an electrode body. In the laminated electrode body and the wound electrode body, a plurality of sheet-like positive electrodes and sheet-like negative electrodes can be used as necessary. In the case of a wound electrode body, the cross section may be shaped to be flat as necessary.

  Examples of the separator relating to the laminated battery include a porous film and a nonwoven fabric made of polyethylene, polypropylene, a fusion of polyethylene and polypropylene, polyethylene terephthalate, polybutylene terephthalate, and the like. The thickness of the separator is preferably 10 to 50 μm, and the porosity is preferably 30 to 70%. Moreover, the effect which prevents a short circuit can be improved and the reliability of a battery can be improved more by using several separators, such as overlapping a porous film and a nonwoven fabric.

As an electrolyte solution for a laminate battery, when the laminate battery of the present invention is a lithium ion secondary battery, for example, a high dielectric constant such as ethylene carbonate (EC), propylene carbonate (PC), γ-butyrolactone (BL), etc. A solution in which a solute such as LiPF ₆ or LiBF ₄ is dissolved in a solvent or an organic solvent such as a linear solvent such as a low viscosity solvent such as dimethyl carbonate (DMC), diethyl carbonate (DEC), or methyl ethyl carbonate (EMC) ( Non-aqueous electrolyte). In addition, it is more preferable to use the mixed solvent of the said high dielectric constant solvent and a low-viscosity solvent as an electrolyte solution solvent. PVDF, rubber-based materials, alicyclic epoxy, oxetane-based materials having a three-dimensional cross-linked structure, and the like may be mixed and solidified into the above solution to form a polymer electrolyte.

  As described above, the laminate film outer package of the laminate-type battery is composed of a metal laminate film, and such a metal laminate film may have at least a metal layer and a heat-sealing resin layer, Although a two-layer structure having only these layers may be used, a three-layer metal laminate film composed of an exterior resin layer / a metal layer / a heat-sealing resin layer is more preferably used.

  In addition, in the metal laminate film, the penetrating portion only has to penetrate only the metal layer from one side to the other side. For example, when a metal laminate film having a three-layer structure having an exterior resin layer is used, the production is Since it becomes easy, also in the exterior resin layer, a portion penetrating from one surface to the other surface may be provided at a position corresponding to the penetrating portion formed in the metal layer.

  Examples of the metal layer in the metal laminate film include an aluminum film and a stainless steel film, and examples of the heat fusion resin layer include a modified polyolefin film (such as a modified polyolefin ionomer film). When the metal laminate film has an exterior resin layer, examples of the exterior resin layer include a nylon film (such as nylon 66 film) and a polyester film [such as a polyethylene terephthalate (PET) film].

  In the metal laminate film, the thickness of the metal layer is preferably 10 to 150 μm, and the thickness of the heat-sealing resin layer is preferably 20 to 100 μm. When the metal laminate film has an exterior resin layer, the thickness is preferably 20 to 100 μm,

  The shape of the laminate film exterior body may be a polygonal shape in plan view. For example, in the plan view, a triangle, a quadrangle, a pentagon, a hexagon, a heptagon, an octagon, etc. may be mentioned. Or a square) is common.

  In the laminate type battery of the present invention, a laminate film outer package formed by folding one metal laminate film in half may be used, or a laminate film outer package formed by stacking two metal laminate films. May be used.

  The laminated battery of the present invention is a conventionally known laminated battery (especially a laminated battery) such as a power supply for various electronic devices, including applications requiring high output and high capacity batteries such as automobile applications. It can be used for the same applications as various applications in which lithium ion secondary batteries) are used.

  Hereinafter, the present invention will be described in detail based on examples. However, the following examples do not limit the present invention.

Example 1
<Preparation of positive electrode>
LiCoO ₂ : 96 parts by mass, acetylene black: 2 parts by mass, and PVDF: 2 parts by mass were mixed, and NMP was further added to prepare a positive electrode mixture-containing paste. The obtained positive electrode mixture-containing paste was applied to both sides of a current collector made of an aluminum foil having a thickness of 15 μm, dried, and then subjected to a press treatment to form a positive electrode mixture layer, whereby a sheet-like positive electrode was obtained. The thickness of the positive electrode mixture layer of the obtained sheet-like positive electrode was 60 μm per one side of the current collector. Thereafter, the obtained sheet-like positive electrode was cut into a shape in which a portion where the positive electrode mixture layer was formed had a width of 110 mm and a length of 200 mm, and also included an exposed portion of the positive electrode current collector that became a current collecting tab.

<Production of negative electrode>
Graphite: 98% by mass, SBR: 1.5% by mass and CMC: 0.5% by mass were added and mixed, and further water was added to prepare a negative electrode mixture-containing paste. The obtained negative electrode mixture-containing paste was applied to both sides of a current collector made of a copper foil having a thickness of 10 μm, dried, and then subjected to a press treatment to form a negative electrode mixture layer, whereby a sheet-like negative electrode was obtained. The thickness of the negative electrode mixture layer of the obtained sheet-like negative electrode was 60 μm per one side of the current collector. Thereafter, the obtained sheet-like negative electrode was cut into a shape in which a portion where the negative electrode mixture layer was formed had a width of 115 mm and a length of 205 mm, and further included an exposed portion of the negative electrode current collector that became a current collecting tab.

<Battery assembly>
10 sheets of the sheet-like positive electrode and 11 sheets of the sheet-like negative electrode were laminated via a separator (a polyolefin microporous film having a thickness of 25 μm) to obtain a laminated electrode body. In addition, it laminated | stacked so that both ends of a laminated electrode body might become a negative electrode. Next, the current collecting tabs of each sheet-like positive electrode according to the laminated electrode body are ultrasonically welded to the positive electrode external terminal made of aluminum, and the current collecting tabs of each sheet-like negative electrode are ultrasonically welded to the negative electrode external terminal made of copper. did. The positive electrode external terminal and the negative electrode external terminal are made of the same modified polyolefin as the resin constituting the heat-sealing resin layer of the exterior body on both surfaces where the heat seal portion of the exterior body is expected to be located. An adhesive layer was placed.

  A metal laminate film (rectangular, size 200 mm × 480 mm) having a thickness of 150 μm and comprising a polyester film / aluminum film / modified polyolefin film was prepared. Then, the laminated electrode body is placed on the modified polyolefin film layer in the metal laminate film so that a part of the positive electrode external terminal and the negative electrode external terminal protrude from the same side of the metal laminate film as shown in FIG. The metal laminate film was folded in half so as to wrap the electrode body.

Thereafter, the side from which the positive electrode external terminal and the negative electrode external terminal are drawn out, the two sides on the front side in FIG. 1, and the side having the folded end are heat-sealed to form a laminate film outer package, which is vacuum dried at 70 ° C. for 15 hours. did. Thereafter, a non-aqueous electrolyte was injected from the vertical side on the back side in FIG. 1, and the vertical side was heat-sealed and sealed under reduced pressure. Note that the nonaqueous electrolytic solution, a solution was used in which a LiPF ₆ in a solvent mixture to 1: 3 to EC and DEC at a volume ratio at a concentration 1.0 mol / l. Moreover, the heat seal width | variety of the laminate film exterior body was all 10 mm.

  Further, as shown in FIG. 1 and FIG. 2, the side where the positive electrode external terminal and the negative electrode external terminal are drawn has a triangular area 50b (see FIG. In FIG. 2, α was 90 ° and H was 8 mm.

  The laminated film outer package after sealing (laminated electrode outer body and laminate film outer package containing a non-aqueous electrolyte solution) is aged for 24 hours, and then charged for 1 hour at a current value of 0.1 C. Locations shown in FIG. 1 and FIG. 2 after performing chemical conversion treatment by carrying out constant current-constant voltage charging (constant current charging: 0.5 C, constant voltage charging: 4.2 V) with a charging time of 4 hours Further, the groove-like through portion 60 having a length of 12 mm and a width of 2 mm is formed, and the width (the length of the side from which the positive electrode external terminal and the negative electrode external terminal are drawn) is 140 mm, the length is 240 mm, and the thickness is 5 mm. A laminated lithium ion secondary battery was obtained. The shortest distance B in the battery of Example 1 is 3.5 mm.

Example 2
A laminated lithium ion secondary battery was produced in the same manner as in Example 1 except that the shape of the penetrating portion 60 was a groove shape with L of 5 mm and width of 2 mm. The shortest distance B in the battery of Example 2 is 8.5 mm.

Example 3
A laminated lithium ion secondary battery was produced in the same manner as in Example 1, except that the shape of the penetrating portion 60 was a groove shape having L of 10 mm and a width of 2 mm. The shortest distance B in the battery of Example 3 is 5 mm.

Comparative Example 1
In the heat seal part of the side where the positive electrode external terminal and the negative electrode external terminal are pulled out in the laminate film outer package, a part protruding inward of the battery from other parts is not formed, and the penetrating part is not formed. A laminated lithium ion secondary battery was produced in the same manner as Example 1 except for the above.

  For the laminated lithium ion secondary batteries of Examples 1 to 3 and Comparative Example 1 (battery before heat-sealing the side where the non-aqueous electrolyte was injected), compressed air was introduced from the side where the non-aqueous electrolyte was injected. Thus, pressure was applied to the laminate film exterior body, and the pressure when the laminate film exterior body was opened was measured. In addition, the said test was implemented about 20 batteries in each Example and the comparative example, and calculated | required the average value of these opening pressures, and its standard deviation. These results are shown in Table 1.

  In the test described above, in all of the batteries of Examples 1 to 3, unsealing of the laminate film outer package occurred in the vent part (formation part of the portion 50b), but in the battery of Comparative Example 1, the unsealing position was constant. I did not. Further, as apparent from Table 1, in the batteries of Examples 1 to 3, the operating pressure (opening pressure) of the vent portion is stable. Further, in the batteries of Example 1 and Example 3 in which L in the penetrating part 60 is increased, the vent part is operated at a lower pressure.

DESCRIPTION OF SYMBOLS 10 Laminated battery 21 Positive electrode external terminal 31 Negative electrode external terminal 40 Laminate film exterior body 50, 50a Heat seal part 50b The part which protruded in the battery inner side rather than the other part among heat seal parts 60 It concerns on a laminate film exterior body The part of the metal laminate film where the metal layer penetrates from one side to the other

Claims (7)

A sheet comprising a metal laminate film obtained by laminating at least a metal layer and a heat-sealing resin layer, having a polygonal laminate film outer package in plan view, and a positive electrode external terminal connected to the inside of the laminate film outer package A laminated battery containing an electrode body having a sheet-like negative electrode to which a negative electrode and a negative electrode external terminal are connected, and a separator,
The laminate film exterior body is composed of two metal laminate films, or is formed by folding one metal laminate film in half,
In the state where the positive electrode external terminal and the negative electrode external terminal are drawn out from the same side in the peripheral portion of the laminate film exterior body, the peripheral portion of the laminate film exterior body is heat-sealed,
Of the peripheral portion of the laminate film outer package, the heat seal portion on the side where the positive electrode external terminal and the negative electrode external terminal are drawn to the outside has a portion protruding to the inner side of the battery from other portions. In addition, in the portion that protrudes inward of the battery from the other portion, a portion that penetrates from one side to the other side is provided in the metal layer of at least one of the laminated metal laminate films, A laminate type battery characterized in that a portion protruding toward the inner side of the battery from other portions is a vent portion.   Of the peripheral part of the laminate film outer package, in the part of the heat seal part on the side where the positive electrode external terminal and the negative electrode external terminal are drawn to the outside, the other part protrudes from the other part to the battery inner side. The laminated battery according to claim 1, wherein the shape of the region heat-sealed further toward the battery inner side is a triangle having one apex on the battery inner side in plan view.   3. The laminated battery according to claim 2, wherein an inner angle of two sides partitioning a heat-sealed region starting from a vertex on the inner side of the battery in the triangle is 20 to 170 °.   Of the peripheral part of the laminate film outer package, the battery inner side of the heat seal part on the side where the positive electrode external terminal and the negative electrode external terminal are drawn to the outside, the part projecting to the battery inner side than the other part The difference H between the heat seal width from the end of the laminate film to the outer edge of the laminate film outer package and the heat seal width from the inner side of the battery to the outer edge of the laminate film outer package is 3 mm or more. The laminated battery according to any one of claims 1 to 3.   Out of the periphery of the laminate film exterior body, the end portion on the inner side of the battery in the heat seal portion on the side where the positive electrode external terminal and the negative electrode external terminal are drawn to the outside, and the outside of the laminate film exterior body L> W, where L (mm) is the shortest distance in plan view between the edge part on the edge side and W (mm) is the heat seal width of the other part in the heat seal part. The laminated battery according to any one of 1 to 4.   Out of the peripheral edge of the laminate film outer package, the end of the penetrating part in the heat seal part on the side where the positive electrode external terminal and the negative electrode external terminal are drawn to the outside, and the battery inner side than the other part The laminate type battery according to any one of claims 1 to 5, wherein the shortest distance B from the end of the protruding portion is 2 mm or more.   Of the peripheral part of the laminate film outer package, the shape of the penetrating part in the heat seal part on the side where the positive electrode external terminal and the negative electrode external terminal are drawn to the outside is linear, substantially circular, substantially The laminated battery according to any one of claims 1 to 6, which has a triangular shape or a substantially rectangular shape.

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