JP2012234670A - Film outer package battery and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery packaged by a film-like exterior material in which destruction of the lead, damage on the film-like exterior material due to movement of the internal battery element caused by vibration or impact, or occurrence of internal short circuit due to displacement of the battery element, in which a positive pole electrode and a negative pole electrode are laminated or wound while sandwiching a separator, is eliminated.SOLUTION: A film outer package battery 1 includes a battery element 5 to which a positive pole terminal 9 and a negative pole terminal 10 are attached, film-like exterior materials 2, 2A, 2B having recesses 4, 4A, 4B for housing the battery elements and covering the battery elements by forming a thermal fusion part 3, and a thermoplastic resin filled part 6 which is thermally fused integrally at the thermal fusion part in the space between the film-like exterior material and the battery element.

Description

  The present invention relates to a film-clad battery in which a battery element is sealed with a film-like packaging material, and a method for producing the same.

Lithium ion secondary batteries are not only used as the main power source for portable electronic devices, but are also used in various devices including batteries for main power sources such as electric vehicles, hybrid vehicles, electric bicycles, and cordless power tools. .
As a battery for a main power source, a battery having a large capacity excellent in energy mass efficiency and volumetric efficiency is required, and a film-covered battery sealed with a thin film-shaped exterior material is preferable.

   Film-like exterior materials are laminated on the inner surface of aluminum foil with a film with good corrosion resistance to electrolytes, such as polyethylene film, polypropylene film, etc., and good heat-sealing properties. A laminated film of a film, a polyethylene terephthalate film or the like is used.

FIG. 5 is a diagram for explaining an example of a film-shaped exterior battery.
5A is a front view, FIG. 5B is a cross-sectional view taken along the line AA ′ in FIG. 5A, and FIG. 5C is a side view.
The film-clad battery 1 is sealed with a film-like packaging material 2 by a heat-sealing part 3, and a positive terminal 9 and a negative terminal 10 for external connection terminals are drawn out from the heat-sealing part.
In the example shown in FIG. 5, two members of the film-shaped exterior material 2 in which the concave portions 4 </ b> A and 4 </ b> B having the same structure are formed, and the battery element 5 is sealed.
In order to store the battery element 5 in the recess formed by forming the film-shaped exterior material 2 using a mold, a storage margin of the battery element 5 is indispensable, and the space between the recess 4 provided in the container and the battery element 5 is indispensable. There is always a gap.

If there is a void inside the film-clad battery, when an impact such as vibration or drop is applied, the battery element may move in the container, the lead part may be destroyed, or the stacked electrodes may be displaced and short-circuited .
In addition, since the battery element 5 is sealed by the film-shaped packaging material 2, when large vibrations are repeatedly applied in three directions, the battery element 5 repeatedly collides with the inner surface of the film-shaped packaging material 2, and the film-shaped packaging material 2. In some cases, the liquid leaks from holes or crevices formed in the four corners of the electrode or the extraction part of the electrode terminal.

  In order to solve the problem caused by vibration in the film-clad battery, Japanese Patent Application Laid-Open No. 2001-307704 (hereinafter referred to as Cited Document 1) includes a filling member that fills between specific portions on the inner wall surface of the battery housing portion. However, the battery element does not prevent the battery element from repeatedly moving inside the film-like exterior material due to vibration, and a sufficient effect cannot be obtained.

Japanese Patent Laid-Open No. 2002-175790 (hereinafter referred to as Cited Document 2) covers each current collector and each lead with an adhesive resin that is insoluble in an electrolytic solution, and this adhesive resin and the outer case A flat battery is described in which each current collector and each lead are coated with an adhesive resin that is insoluble in the electrolyte solution, and each lead portion is covered with an adhesive resin. However, there is a problem in that it is insufficient with respect to impact and may be deteriorated by covering with an adhesive resin filled with the battery element portion.
Further, in Japanese Patent Laid-Open No. 2003-109557 (hereinafter referred to as Cited Document 3), the position of the power generation element and the container is shifted due to a large impact or the like, and the lead portion that extracts current from the power generation element to the outside of the container is damaged. In order to solve the problem that there is a possibility that the lead will be removed, a non-aqueous electrolyte battery is described in which the lead and the inner surface of the bag-like container are fixed using a resin. Met.

JP 2001-307704 A JP 2002-175790 A JP 2003-109557 A

  In a film-clad battery in which a battery element is packaged with a film-shaped packaging material, destruction of a lead portion caused by movement of the internal battery element due to vibration, impact, etc., damage to a fill-shaped packaging material, or a positive electrode or a negative electrode It is an object of the present invention to provide a battery that is packaged with a film-shaped exterior material in which an internal short circuit or the like does not occur due to a shift of a battery element that is laminated or wound with a separator interposed therebetween.

The present invention includes a battery element having a positive electrode terminal and a negative electrode terminal attached thereto, a film-shaped exterior material that has a recess for accommodating the battery element, forms a heat-sealed portion, and covers the battery element, and the film-shaped exterior material And a battery-covered battery having a thermoplastic resin filling part integrally heat-sealed at the heat-sealing part in a space between the battery element and the battery element.
The film exterior, wherein the battery element is either a laminated body in which a positive electrode and a negative electrode are laminated via a separator, or a wound body in which a belt-like positive electrode and a negative electrode are wound through a separator, respectively. It is a battery.
In the above-described film-covered battery, the softening temperature of the synthetic resin filled in the thermoplastic resin-filled portion is the same as or lower than the softening temperature of the heat-sealed portion of the film-shaped exterior material.
It is the said film exterior battery which is a lithium ion battery.

The battery element to which the positive electrode terminal and the negative electrode terminal are attached is accommodated in the concave portion of the film-shaped packaging material, and extends in the space direction between the battery element and the film-shaped packaging material from the portion where the film-shaped packaging material is heat-sealed. A thermoplastic resin film is placed, the thermoplastic resin film is heated from the outer surface on the film-like exterior material side, and a heat-sealed portion of the film-like exterior material is heated and pressed, and the film-like exterior material and the battery This is a method for manufacturing a film-clad battery in which a thermoplastic resin filling portion formed integrally with a heat fusion portion is formed in a space between elements.
Heat-pressed by a pair of heat-sealing means provided with inclined surfaces that increase the distance from the outer peripheral portion of the portion to be thermally fused toward the thermoplastic resin filling portion, and the thermoplastic resin from the portion to be thermally fused It is the manufacturing method of the said film-clad battery which heat-seal | fuses while extruding the thermoplastic resin softened to the filling part direction.
The film exterior, wherein the battery element is either a laminated body in which a positive electrode and a negative electrode are laminated via a separator, or a wound body in which a belt-like positive electrode and a negative electrode are wound through a separator, respectively. It is a manufacturing method of a battery.
It is a manufacturing method of the said film exterior battery which is a lithium ion battery.

The present invention includes a film-shaped packaging material that has a concave portion for accommodating the battery element, the battery element having the positive electrode terminal and the negative electrode terminal attached thereto, covers the battery element by forming a heat-sealed portion, and the film-shaped packaging material. The space between the battery elements is provided with a thermoplastic resin filling portion integrally fused with the heat fusion portion, and the thermoplastic resin filling portion is integrated with the fusion portion of the film-like exterior material. The thermoplastic resin filling portion does not move due to impact, vibration or the like.
As a result, it is possible to provide a film-clad battery in which the battery element is prevented from moving inside the film-shaped packaging material due to impact and vibration to damage the film-shaped packaging material or damage to the positive electrode terminal and the negative electrode terminal. .

FIG. 1 is a diagram illustrating one embodiment of a film-clad battery according to the present invention. FIG. 2 is a diagram for explaining another embodiment of the film-clad battery of the present invention. FIG. 3 is a diagram for explaining one embodiment of a method for producing a film-clad battery of the present invention. FIG. 4 is a diagram for explaining a heating means used for producing the film-clad battery of the present invention. FIG. 5 is a diagram for explaining a conventional film-clad battery.

  In the present invention, the thermoplastic resin filling part integrated with the heat-sealing part for sealing the film-like exterior material is provided in the space between the inner surface of the film-like exterior material of the battery and the battery element that is sheathed by the film-like exterior material. The present inventors have found that it is possible to provide a battery whose characteristics are not deteriorated by vibration or impact applied to the battery.

FIG. 1 is a diagram for explaining one embodiment of the battery of the present invention.
1A is a front view, FIG. 1B is a cross-sectional view taken along line AA ′ in FIG. 1A, and FIG. 1C is a side view.
The film-clad battery 1 is sealed by providing a heat-sealed part 3 on a film-shaped packaging material 2, and a positive electrode terminal 9 and a negative electrode terminal 10 for external connection terminals are drawn out from the sealed part.
A recess 4 is formed in the film-shaped exterior material 2 on both sides, and battery elements 5 indicated by broken lines in FIG. 1A are accommodated in the recesses 4A and 4B of the film-shaped exterior materials 2A and 2B, respectively. Yes.
A thermoplastic resin filling portion 6 is formed between the concave portion 4 formed in the film-shaped exterior material 2 and the battery element 5, and the thermoplastic resin filling portion 6 is integrated in the heat fusion portion 3. .

Therefore, even when a large impact or vibration is applied to the film-clad battery 1 due to the fall of the battery or the like, the periphery of the battery element 5 is fixed by the thermoplastic resin filling part 6 integrated with the heat fusion part 3. 5 does not collide with the inner surface of the film-shaped exterior material 2. For this reason, the lead part of the positive electrode terminal 9 and the negative electrode terminal 10 can be destroyed, or the shift | offset | difference of the electrode of a battery element can be prevented.
In addition, since the battery element 5 does not repeatedly collide with the inner surface of the film-shaped packaging material 2, it is possible to prevent the formation of holes and tears at the four corners of the film-shaped packaging material 2, the positive electrode terminal 9, and the extraction portion of the negative electrode terminal 10. .

FIG. 2 is a diagram illustrating another embodiment of the battery of the present invention.
In the battery shown in FIG. 1, the battery element is stored in the recess formed in each of the two film-shaped exterior materials, whereas the battery shown in FIG. One of the battery element storage portions is a recess 4 provided in the film-shaped exterior material 2A, and the other is formed by a flat film-shaped exterior material 2B.
In the battery of this embodiment, since one surface has a flat surface in the center and the peripheral portion, the outer shape is different from the battery in which the storage portion is formed by the two concave portions shown in FIG. The combination of both can increase the degree of freedom of battery installation.

The battery manufacturing method of the present invention will be described below with reference to the drawings.
FIG. 3 is a cross-sectional view for explaining one embodiment of the battery manufacturing method of the present invention.
As shown in FIG. 3 (A), a film-like exterior material in which a metal foil such as an aluminum foil and a plurality of synthetic resin films are laminated, with a polypropylene film on one side and a polyethylene terephthalate film on the other side A recess 4A for storing battery elements is formed on the film-shaped exterior material 2A in which the battery elements are stacked using a mold.

  A frame-shaped thermoplastic resin film 6A extending from a portion 3A in which the battery element 5 is housed in the recess 4A of the film-shaped exterior material 2A and heat-sealed to heat-bond to the space between the battery element 5 and the recess 4 Place. Next, the battery element 5 provided with the positive electrode terminal (not shown) and the negative electrode terminal 10 is accommodated in the recess 4A.

  As shown in FIG. 3 (B), a frame-shaped thermoplastic resin film 6B similar to the thermoplastic resin film 6A previously disposed is disposed between the heat-sealed portion and the battery element 5 and the recess 4. And the battery element 5 is arrange | positioned so that it may cover with the recessed part 4 of the film-form exterior material 2B.

  Next, the thermoplastic resin film 6A located in the heat-sealed portion 3A of the film-like exterior materials 2A and 2B is heated from the outer surface on the film-like exterior material side, and the portion 3A of the film-like exterior material is heat-sealed. Is heat-pressed by means of heat-sealing means to form a thermoplastic resin filling portion 6 integrally formed with the heat-sealing portion 3 in the internal space between the film-like exterior materials 2A, 2B and the battery element 5. .

As the heat fusion means, means utilized for heat fusion of the heat-fusible film can be used. The heat fusion process suitable for this invention is demonstrated below.
FIG. 4 is a diagram for explaining the thermal adhesion process, and FIG. 4 (A) is a diagram for explaining the thermal fusion apparatus and is a sectional view. FIG. 4B is a diagram for explaining the heat-sealing block, and FIG. 4C is a partial cross-sectional view of the battery for explaining the heat-sealed heat-sealed portion.
The heat-sealing means 20 has two heating blocks 22A and 22B that sandwich the portions to be heat-sealed from both sides and perform heat-sealing at the same time, as shown in FIG. 4B. An inclined surface 24 and a flat portion 26 are provided so that the distance from each other increases toward the space 7 filled with the thermo-thermoplastic resin from the outer peripheral portion of the portion.

When the heat-sealed portion is heated and pressed by the heat-sealing blocks 22A and 22B, the thermoplastic resin films 6A and 6B disposed in the heat-sealed portions are softened and directed toward the inside of the heat-sealing blocks 22A and 22B. The space 7 between the battery element 5 and the film-like exterior materials 2A and 2B is fed by being extruded from the outside to the inside by the inclined surfaces of the heat fusion blocks.
As a result, as shown in FIG. 4C, in the space 7 between the battery element 5 and the film-like exterior materials 2A and 2B, a thermoplastic resin filling portion 6 integrated with the heat fusion portion is formed.

  As shown in FIG. 4, when an inclined surface with an interval extending from the outside toward the inside is provided and heat-sealed, the heat-sealed portion on the inner surface of the film-like exterior material is directed inward along the inclined surface. Since the force acts, the thickness of the end surface 3C of the heat-sealed portion which is the outer surface side portion of the heat-welded portion 3 is small. As a result, the area of the portion facing the outer surface of the heat-sealed portion is reduced, and the effect of improving the air tightness of the heat-sealed portion and improving the moisture permeation preventing performance can be obtained.

  The film-like exterior material usable in the present invention is a biaxially stretched polyester film such as a biaxially stretched polyethylene naphthalate film and a biaxially stretched polybutylene terephthalate film excellent in various strengths and resistances, in addition to the polyethylene terephthalate film. Alternatively, a biaxially stretched nylon film or the like can be used alone or a laminated film in which a plurality of layers are laminated.

  Also, polypropylene or acid-modified polypropylene can be used for the inner heat-sealing layer. As the acid-modified polypropylene, one modified with an unsaturated carboxylic acid such as acrylic acid, methacrylic acid or maleic acid can be used.

When the film-clad battery of the present invention is a lithium ion battery, the following battery elements can be cited as an example.
The battery element is an electrode assembly in which a flat positive electrode and a flat negative electrode are laminated via a separator.
As the positive electrode, a lithium current transition metal composite oxide such as LiCoO ₂ , LiNiO ₂ , LiMn ₂ O _4, etc., a conductive material such as carbon black, polyvinylidene fluoride (PVDF), etc. After forming a positive electrode active material layer on one side of the positive electrode current collector, the positive electrode paint prepared by dispersing and mixing in a binder and a solvent such as N-methyl-2-pyrrolidone (NMP) was applied by a coating apparatus and dried. Similarly, a positive electrode paint is applied to a predetermined portion on the opposite surface of the positive electrode current collector, and a positive electrode active material layer is formed on both surfaces.

  The negative electrode has a negative electrode current collector made of a strip-shaped copper foil, and can be doped and dedoped with lithium ions. An organic polymer compound fired body obtained by firing carbon, phenol resin, furan resin, etc., carbonaceous material such as carbon fiber, activated carbon, etc., conductive polymer material such as polyacetylene, polypyrrole, etc., conductive material such as carbon black, polyfluoride, etc. A negative electrode paint prepared by dispersing and mixing in a binder such as vinylidene fluoride (PVDF) and a solvent such as N-methyl-2-pyrrolidone (NMP) is applied by a coating apparatus and dried to form a negative electrode active material layer of the negative electrode current collector After forming on one side, a negative electrode coating material is similarly applied to a predetermined portion on the opposite surface of the negative electrode current collector to form a negative electrode active material layer on both sides.

Example 1
A film-like exterior in which a biaxially stretched polyethylene terephthalate film layer having a thickness of 12 μm, an aluminum foil layer having a thickness of 40 μm, a biaxially stretched nylon film layer having a thickness of 20 μm, and a heat-sealing layer composed of a polypropylene film having a thickness of 40 μm are sequentially laminated. A concave portion having a length of 163 mm, a width of 119 mm, and a depth of 3.4 mm was formed on each of the two materials using a mold.
A lithium ion battery element having a length of 160 mm, a width of 116 mm, and a thickness of 7 mm, in which a positive electrode terminal and a negative electrode terminal are attached to one concave portion of the exterior film, is accommodated, and the thickness of the same material as that of the heat fusion layer is 0. A 3 mm polypropylene film is cut into an outer shape of 183 mm x 139 mm and an inner shape of 163 mm x 119 mm, and is placed so that the periphery is located at the heat-sealed portion of the exterior film. An exterior film was placed.

  Next, the lead-out side of the electrode terminal is a heat-sealed part with a width of 20 mm, and the other three sides are heat-fused parts with a width of 15 mm. From the flat part up to 10 mm from the inner end of the heat-fused part, Three sides excluding one side on the long side serving as a liquid injection port, with heat fusion means having an inclined surface with a height of 0.1 mm compared to the flat portion facing the outer end of the landing portion on both sides Was heat-sealed by heating at a temperature of 150 ° C. and a pressure of 0.3 MPa for 10 seconds to obtain a battery outer package containing battery elements. After injecting the electrolyte from the electrolyte inlet into the outer package, one side of the electrolyte inlet was heat-sealed under the same conditions as the above-mentioned fusion conditions to produce a completely sealed lithium ion battery. .

  The fabricated battery was dropped from a height of 1.5 m onto a concrete floor 20 times with the lead part down, and then the battery was disassembled and checked by checking for defects such as cracks in the lead part. . The battery by the conventional method had cracks in the foil of the lead part in 4 out of 10 batteries. None of the devices according to the present invention were confirmed to be damaged such as cracks.

  The present invention does not add a special process or change the shape of the battery, and by disposing a thermoplastic resin film on the part to be heat-sealed and heat-sealing, the battery element and the film-like exterior material The thermoplastic resin filling portion solidified after flowing so as to fill the gap between the container and the container produced by the step is formed integrally with the heat-sealed portion of the film-like exterior material, and the battery element is placed through the thermoplastic resin filling portion. Therefore, even if deformation pressure is applied to the battery due to shocks such as vibration or dropping, the battery element is not fixed to the container and does not move, the internal battery element stacking does not shift, and the lead part Deformation is suppressed and impact resistance is increased.

  DESCRIPTION OF SYMBOLS 1 ... Film-clad battery, 2, 2A, 2B ... Film-like exterior material, 3 ... Thermal fusion part, 3A ... Thermal fusion part, 3C ... Thermal fusion part end surface, 4, 4A, 4B ... Recessed part, 5 DESCRIPTION OF SYMBOLS Battery element, 6 ... Thermoplastic resin filling part, 6A, 6B ... Thermoplastic resin film, 9 ... Positive electrode terminal, 10 ... Negative electrode terminal, 20 ... Thermal fusion | fusion means, 22A, 22B ... Heating block, 24 ... Inclined surface, 26: Flat part

Claims (8)

A battery element with a positive terminal and a negative terminal attached;
A film-like exterior material that has a concave portion for accommodating the battery element, forms a heat-sealing portion, and covers the battery element;
A film-covered battery comprising a thermoplastic resin filling portion integrally heat-sealed at the heat-sealing portion in a space between the film-shaped exterior material and the battery element.   The battery element is either a laminate in which a positive electrode and a negative electrode are stacked via a separator, or a wound body in which each of the belt-shaped positive electrode and the negative electrode is wound through a separator. The film-clad battery according to claim 1.   3. The film exterior according to claim 1, wherein a softening temperature of the synthetic resin filled in the thermoplastic resin filling portion is equal to or lower than a softening temperature of the heat-sealed portion of the film-shaped exterior material. battery.   The film-clad battery according to any one of claims 1 to 3, wherein the film-clad battery is a lithium ion battery. The battery element to which the positive electrode terminal and the negative electrode terminal are attached is accommodated in the concave portion of the film-like exterior material,
Placed a thermoplastic resin film extending in the space direction between the battery element and the film-shaped exterior material from the portion heat-sealed when sealing the film-shaped exterior material,
While heating the thermoplastic resin film from the outer surface on the film-like exterior material side, heat-pressing the portion to be heat-sealed of the film-like exterior material,
A method for producing a film-clad battery, comprising forming a thermoplastic resin filling part integrally formed with a heat-sealing part in a space between the film-shaped packaging material and the battery element. Heat-pressed by a pair of heat-sealing means provided with inclined surfaces that increase the distance from the outer peripheral part of the part to be thermally fused toward the thermoplastic resin filling part,
6. The method for producing a film-clad battery according to claim 5, wherein the thermoplastic resin softened from the heat-sealed portion toward the thermoplastic resin filling portion is heat-sealed while being extruded.   The battery element is either a laminate in which a positive electrode and a negative electrode are stacked via a separator, or a wound body in which each of the belt-shaped positive electrode and the negative electrode is wound through a separator. The manufacturing method of the film-clad battery of Claim 5 or 6.   It is a lithium ion battery, The manufacturing method of the film-clad battery of any one of Claim 5 to 7 characterized by the above-mentioned.

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