JP5168778B2 - Battery exterior body and battery using the same - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a battery exterior body exhibiting stable sealing performance and durability, and a battery using the same.

  Conventionally, for example, chemical energy of lithium ion batteries, lithium polymer batteries, fuel cells, etc., or liquid capacitors including dielectric materials such as liquids, solid ceramics, and organic substances, electrolytic capacitors such as solid capacitors, double layer capacitors, etc. Various batteries including an element that converts the energy into electric energy are widely used in personal computers, portable terminal devices (cell phones, PDAs, etc.), video cameras, electric vehicles, energy storage batteries, robots, satellites, and the like. As these battery outer bodies, metal cans formed by pressing metal into cylindrical or rectangular parallelepiped containers, or laminates made of composite films obtained by laminating plastic films, metal foils, etc., in the form of bags What was made (henceforth an exterior body) was used.

  However, there are the following problems as a battery outer package. In a metal can, since the outer wall of the container is rigid, the shape of the battery itself is determined. Therefore, since the hardware side is designed in accordance with the battery, the size of the hardware using the battery is determined by the battery, and the degree of freedom in shape is lost. On the other hand, a pouch type that has a laminated body in a bag shape and accommodates a battery body, or an outer body that is embossed by pressing the laminated body, is a hardware that uses a battery by the battery itself, like the metal can. Although there is no restriction on the degree of freedom in the shape design, packaging materials that can sufficiently satisfy the physical properties and functions required for battery exterior bodies have not yet been developed.

  The physical properties and functions required for the exterior body are high moisture resistance or surface insulation, and moisture resistance is particularly important. The packaging material is a laminate composed of at least a base material layer, a barrier layer, and a heat seal layer, and the material strength of each layer and the adhesive strength between the layers affect the necessary properties as a battery outer package. Has been confirmed. For example, if the adhesive strength between the barrier layer and the heat seal layer is insufficient, water vapor may enter from the outside, and fluorination generated by the reaction between the electrolyte in the component forming the lithium ion battery and the water vapor. There is a problem that dehydration (peeling) occurs between the barrier layer and the heat seal layer due to corrosion of the aluminum surface, which is the barrier layer, by the hydrogen acid. Various proposals have been made for this problem.

  Conventionally, as a method for sealing a battery tab portion, a polyolefin resin having a thermal adhesive property on an inner layer sealed by a peripheral thermal bonding portion by sandwiching a battery tab connected to each of a positive electrode and a negative electrode in a state of protruding outward A polyolefin layer on both sides of a biaxially stretched polyethylene naphthalate film between the heat seal layer of the peripheral heat-bonding portion of the outer package and the battery tab comprising at least a barrier layer made of a metal foil, and the polyolefin layer There has been a method of interposing an adhesive film for sealing a battery metal terminal part, wherein at least one is an acid-modified polyolefin layer.

  By this method, the acid-modified polyolefin layer is excellent in the thermal adhesiveness to the battery tab and sealed in the peripheral thermal adhesive portion that is sandwiched between the battery tabs and thermally bonded, and the biaxially stretched polyethylene naphthalate film is water vapor. Because it has excellent heat resistance as well as barrier properties, when sealed, it remains without becoming thin due to heat and pressure of heat sealing, and high performance sealing such as prevention of short circuit between the barrier layer and the battery tab was realized. . (See Patent Document 1).

  However, in the packaging of the battery 1 as shown in FIG. 5 (a), the cross section of the side where the battery tab 4 is sandwiched and heat-sealed is a metal foil of a laminate constituting the outer package as shown in FIG. 5 (b). Layer 8 is exposed. If the battery tab is made of a flexible metal, the battery tab 4 in a portion extending from the cross section is curved, and the cross section of the metal foil layer 8 exposed on the end face of the exterior body as shown in FIG. There was a case where it touched and short-circuited. Therefore, as a method for avoiding such a short circuit, as shown in FIG. 6A, when the battery metal terminal portion sealing adhesive film 22 is bonded to the battery tab 4, it is 1 to 5 mm from the cut surface of the outer package. The coating layer of the adhesive film 22 for sealing the battery metal terminal portion was present (exposed coating) to the outer side. Thus, if the coating layer of the battery metal terminal portion sealing adhesive film 22 is outside the cut surface, even if the battery tab 4 is curved, as shown in FIG. Since the sealing adhesive film 22 functions as an insulating layer, a short circuit can be avoided. However, providing the exposed film with a predetermined width is extremely troublesome and has been an obstacle to productivity.

In addition, after sealing, when processing according to the shape of a mobile phone or the like, or due to external force applied after the battery becomes a product, cracks occur in the barrier layer of the exterior body and the electrolyte leaks, or the heat seal layer cracks. Also, there was a problem that the electrolyte and the metal foil layer were in contact with each other and the insulation of the battery itself could not be maintained.
JP 2004-95543 A

  In view of the above problems, a battery that reliably seals a portion including a tab portion of a battery body and prevents a leakage of an electrolyte due to partial breakage of the exterior body or a short circuit between the battery tab and the exterior body metal foil layer during heat sealing. Providing an outer package, a battery packaging method for preventing a short circuit between the battery tab after heat sealing and the metal foil layer cross section of the outer package, and providing a battery having high durability and safety even in long-term use. .

  To achieve the above object, the present invention provides a positive electrode comprising a positive electrode active material and a positive electrode current collector, a negative electrode comprising a negative electrode active material and a negative electrode current collector, and an electrolyte filled between the positive electrode and the negative electrode. A metal foil including a battery main body, and an outer package that houses the battery main body and heat seals the peripheral portion thereof to seal the battery main body, and includes a base material layer and at least a chemical conversion treatment layer on a surface that becomes the storage portion side A battery outer body comprising a multilayer film having a structure in which a layer, an acid-modified polyolefin layer, a heat-resistant resin layer, and a heat-adhesive resin layer are laminated in this order.

  With this structure, the metal foil layer and the heat-adhesive resin layer are laminated with the heat-resistant resin layer interposed therebetween, so that the metal foil layer cracks due to external force applied in the electrolyte injection process and the folding process after sealing. In this case, the heat-resistant resin layer serves as a barrier layer and prevents leakage of the electrolyte. In addition, when a crack occurs in the heat-adhesive resin that is the innermost layer of the outer package, the insulating property of the heat-resistant resin layer prevents a short circuit due to contact between the electrolyte and the metal foil layer. The main body can exhibit stable performance even for long-term use.

  The second configuration of the present invention is characterized in that, in the battery exterior body of the first configuration, the melting point of the heat resistant resin layer is 200 ° C. or higher.

  With this configuration, when the main body of the lithium ion battery is sealed with the exterior body, since the melting point of the thermoadhesive resin is usually 170 ° C. to 180 ° C., the battery tab is sandwiched and the outer periphery of the exterior body is heated and pressurized to heat seal. At this time, since the heat-resistant resin layer remains without being thinned, it is possible to prevent a short circuit due to contact between the metal foil layer in the outer package and the battery tab.

  According to a third configuration of the present invention, in the battery exterior body according to the first or second configuration, the heat-adhesive resin layer is made of an acid-modified polyolefin.

  With this configuration, the acid-modified polyolefin having high metal adhesiveness is strongly bonded to the battery tab which is a metal terminal, and the sealing property between the heat-adhesive resin layer and the battery tab is secured.

  According to a fourth configuration of the present invention, in the battery exterior body according to the first or second configuration, the heat-adhesive resin layer includes an acid-modified polyolefin layer and a polyolefin layer, and the acid-modified polyolefin layer is a heat-resistant resin layer. It is arranged on the side.

  By this configuration, a polyolefin layer having excellent processability and low cost compared to acid-modified polyolefin is laminated on the heat-adhesive resin layer, and it is possible to provide a battery case that can cope with an increase in the size of a lithium ion battery. it can.

  A fifth configuration of the present invention is characterized in that, in the battery exterior body according to any one of the first to fourth configurations, an adhesive layer is provided between the heat-resistant resin layer and the acid-modified polyolefin layer. To do.

  With this configuration, the sealing performance between the heat-resistant resin layer and the acid-modified polyolefin layer can be improved.

  According to a sixth configuration of the present invention, in the battery exterior body according to the fourth configuration, the heat resistant resin layer is made of a biaxially stretched polyethylene naphthalate film.

  With this configuration, the biaxially stretched polyethylene naphthalate film has excellent heat resistance, and the melting point is sufficiently higher than the temperature of the heat seal, so that when sealing, the remaining metal foil layer and the battery tab are short-circuited without becoming thin. Since the biaxially stretched polyethylene naphthalate film has a low water vapor permeability, it blocks external water vapor that permeates from the sandwiched portion of the battery tab, and generates hydrofluoric acid by the reaction between the electrolyte and water vapor. Can be suppressed.

  According to a seventh configuration of the present invention, in the battery exterior body of the sixth configuration, the aminated phenol polymer, the trivalent chromium compound, and the phosphorus compound are contained on both surfaces of the biaxially stretched polyethylene naphthalate film. An adhesion promoter is formed.

  With this configuration, the interlayer strength between the biaxially stretched polyethylene naphthalate film and the acid-modified polyolefin layer can be improved.

  According to an eighth configuration of the present invention, there is provided a positive electrode comprising a positive electrode active material and a positive electrode current collector, a negative electrode active material and a negative electrode current collector, using the battery outer package having any one of the first to seventh configurations. A battery body comprising: a negative electrode comprising: a positive electrode; and an electrolyte filled between the positive electrode and the negative electrode.

  With this configuration, a battery with excellent manufacturing efficiency and durability can be provided.

  According to a ninth configuration of the present invention, in the battery packaging method, the battery main body is housed in the battery exterior body according to any one of the first to seventh configurations, the thermoadhesive resin layers face each other, A package for sealing the battery main body by heat-sealing the periphery, and extending both exterior bodies of the side to be heat-sealed by sandwiching the battery tab to an extension end, and at least one outer end of the extension end And the exterior body is deformed and held in the folded state.

  With this configuration, it is possible to prevent a short circuit between the cross section of the metal foil layer of the outer package and the battery tab in the battery packaging.

  According to a tenth aspect of the present invention, there is provided a battery characterized in that the battery main body is hermetically sealed by the battery exterior body by the battery packaging method of the ninth structure.

  With this configuration, it is possible to provide a battery having high durability and safety even when used for a long time.

  Hereinafter, the battery case of the present invention will be described with reference to the drawings. FIG. 1A is a perspective view of a pouch-type battery 1, and FIG. 1B is a perspective view showing a state in which the battery 1 is disassembled. As shown in FIGS. 1A and 1B, the pouch-type battery 1 is composed of a battery body 2 and an exterior body 5, and the battery body 2 housed in the exterior body 5 seals its periphery. By doing so, moisture resistance is imparted.

  The battery body 2 includes a positive electrode composed of a positive electrode active material and a positive electrode current collector, a negative electrode composed of a negative electrode active material and a negative electrode current collector, and an electrolyte filled between the positive electrode and the negative electrode (both not shown). A cell (power storage unit) 3 and a tab (electrode terminal) 4 that is connected to a positive electrode and a negative electrode in the cell 3 and has a tip projecting outside the exterior body 5 are configured.

  The battery 1 includes a pouch type using a pillow-shaped exterior body 5 as shown in FIG. 1 and a tray 5a formed with an embossed portion as shown in FIG. 2 depending on the type of exterior body that wraps the battery body. There is an embossed type in which the lithium ion battery main body 2 is hermetically housed using the exterior body 5 including the sheet 5b, but the present invention can be applied to any type.

  Next, the material of the battery outer body of the present invention will be described. FIG. 3 is a cross-sectional view of the exterior body. As shown in FIG. 3A, the laminated body 6 forming the exterior body includes at least a base material layer 7, a metal foil layer 8 provided with a chemical conversion treatment layer on both surfaces, an acid-modified polyolefin layer 9, and a heat resistant resin layer. 10, composed of a heat-adhesive resin layer 11, and an adhesive layer 14 is provided between these layers, which are laminated by a dry lamination method, a sandwich lamination method, an extrusion lamination method, a thermal lamination method, or the like. FIG. 3B is a cross-sectional view of a battery outer package in which the thermal adhesive resin layer 11 is composed of an acid-modified polyolefin layer 12 and a polyolefin layer 13.

  The base material layer 7 is made of stretched polyester or nylon film. In this case, examples of the polyester resin include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, copolymerized polyester, and polycarbonate. Examples of the nylon resin include polyamide resins such as nylon 6, nylon 6,6, copolymers of nylon 6,6 and nylon 6, nylon 6,10, polymetaxylylene adipamide (MXD6), and the like. It is done.

  When the base material layer 7 is used as a lithium ion battery, the base material layer 7 is a part that is in direct contact with the hardware. Considering the existence of pinholes in the film alone and the occurrence of pinholes during processing, the base material layer needs to have a thickness of 6 μm or more, and preferably 12 to 25 μm.

The base material layer 7 can be laminated in order to improve pinhole resistance and insulation when used as a battery outer package. When the base material layer 7 is laminated, the outermost layer includes at least one resin layer of two or more layers, and the thickness of each layer is 6 μm or more, preferably 12 to 25 μm. Examples of laminating the outermost layer include the following 1) to 7) although not shown.
1) Stretched polyethylene terephthalate / stretched nylon 2) Stretched nylon / stretched polyethylene terephthalate

In addition, mechanical suitability of packaging materials (stability of conveyance in packaging machines and processing machines), surface protection (heat resistance and electrolyte resistance), secondary processing and embossing type outer packaging for lithium ion batteries (See Fig. 2) For the purpose of reducing the frictional resistance between the mold and the outermost layer during embossing, the outermost layer is multilayered, and the surface of the outermost layer is a fluororesin layer, an acrylic resin layer, a silicone system It is preferable to provide a resin layer or the like. For example,
3) Fluorine resin / stretched polyethylene terephthalate (Fluorine resin is a film or formed by drying after liquid coating)
4) Silicone resin / stretched polyethylene terephthalate (silicone resin is a film or formed by drying after liquid coating)
5) Fluorine-based resin / stretched polyethylene terephthalate / stretched nylon 6) Silicone-based resin / stretched polyethylene terephthalate / stretched nylon 7) Acrylic resin / stretched nylon (Acrylic resin is film-like or cured after drying by liquid coating)

  As a laminating method for forming the outer package having a laminated structure, a dry laminating method, a thermal laminating method, an extrusion laminating method, a sandwich laminating method, a coextrusion laminating method, or the like can be used.

  The metal foil layer 8 is a layer for preventing water vapor from entering the inside of the lithium ion battery from the outside through the exterior body 5, and pinholes and processing suitability (pouching, embossing) of the metal foil layer alone. In order to stabilize the film and to have pinhole resistance, a metal such as aluminum or nickel having a thickness of 15 μm or more, or a film on which an inorganic compound such as silicon oxide or alumina is deposited may be used. Is preferably aluminum of 15 μm to 100 μm.

  By using aluminum having an iron content of 0.3 to 9.0% by weight, preferably 0.7 to 2.0% by weight as the material of the metal foil layer 8, compared with aluminum not containing iron. In addition, aluminum has good spreadability, the occurrence of pinholes due to bending as a laminated body is reduced, and the side wall can be easily formed when embossing an embossed type exterior body. When the iron content is less than 0.3% by weight, effects such as prevention of pinholes and improvement in embossing formability are not observed, and the iron content of the aluminum is 9.0% by weight. When exceeding, the softness | flexibility as aluminum is inhibited and bag-making property worsens as a laminated body.

  In addition, aluminum produced by cold rolling changes its flexibility, waist strength, and hardness under annealing (so-called annealing treatment) conditions, but the aluminum used in this example is not annealed. A soft processed product having flexibility, which is appropriately annealed, is preferable to the product. The degree of flexibility, waist strength and hardness, that is, annealing conditions may be appropriately selected in accordance with processing suitability (pouching, embossing suitability). For example, in order to prevent pinholes and wrinkles during embossing, aluminum that tends to be softer and more or less annealed than hard aluminum that has not been annealed is better.

  Furthermore, a chemical conversion treatment layer 15 made of an oxide film is provided on the surface of the metal foil layer 8. The chemical conversion treatment layer 15 prevents corrosion and dissolution of the surface of the metal foil layer 8 due to hydrogen fluoride generated by the electrolyte and moisture, and improves the adhesion (wetting property) of the surface of the metal foil layer 8 to form a laminate. The adhesive force between the metal foil layer 8, the base material layer 7 and the acid-modified polyolefin 9 is stabilized.

  The heat-adhesive resin layer 11 laminated on the exterior body of the present invention has heat-sealing properties between the heat-adhesive resin layers, and also exhibits heat-sealing properties with respect to the metal forming the tab, and As a result of examining materials that do not change or deteriorate depending on the contents, unsaturated carboxylic graft polyethylene, unsaturated carboxylic acid having a thickness of 10 μm or more, preferably 20 to 100 μm, a melting point of 80 ° C. or more, and a Vicat softening point of 70 ° C. or more At least one of an unsaturated carboxylic grafted polyolefin resin such as grafted polypropylene, unsaturated carboxylic grafted polymethylpentene, metal ion crosslinked polyethylene, or a copolymer of ethylene or propylene and acrylic acid or methacrylic acid, and a modified product thereof Those containing one showed good results.

  The unsaturated carboxylic graft polyolefin resin is suitable for any of adhesion to electrodes, heat resistance, cold resistance, and processability (pouching, embossing formability). If the thickness of the innermost layer is less than 20 μm, when the electrode is heat-sealed, a gap is formed at the end portion and the barrier property is lost. Moreover, even if the thickness of the innermost layer exceeds 100 μm, the heat seal strength does not change, and the thickness of the laminated body increases, which goes against the space-saving that is the subject of the present invention. Moreover, when melting | fusing point and Vicat softening point are low, heat resistance and cold resistance will lose | eliminate, the adhesive strength with films and an electrode will fall, and a bag will break. The various unsaturated carboxylic graft polymers may be used alone, but the properties can also be satisfied by blending two or more kinds of resins.

  For each layer of the battery outer body of the present invention, for the purpose of improving and stabilizing film forming properties, lamination processing, suitability for final product secondary processing (pouching, embossing molding), corona treatment, Surface activation treatment such as blast treatment, oxidation treatment, and ozone treatment may be performed.

  The lamination method of each layer of the base material layer 7, the metal foil layer 8, the acid-modified polyolefin layer 9, the heat-resistant resin layer 10, and the heat-adhesive resin layer 11 of the exterior body of the present invention is specifically T-die. The film can be formed using a method, an inflation method, a coextrusion method, or the like. If necessary, the secondary film may be formed by a method such as coating, vapor deposition, ultraviolet curing, or electron beam curing. Moreover, as a bonding method, methods such as a dry laminating method, an extrusion laminating method, a coextrusion laminating method, and a thermal laminating method can be used.

  When bonding by dry laminating method, polyester, polyethyleneimine, polyether, cyanoacrylate, urethane, organic titanium, polyetherurethane, epoxy, polyesterurethane, imide, isocyanate Various adhesives based on polyolefin, polyolefin, and silicone can be used. In addition, these adhesive layers appropriately contain at least one of silicon oxide, calcium carbonate, zinc, red lead, lead suboxide, lead oxide, lead cyanamide, zinc chromate, barium potassium chromate, and barium zinc chromate. Addition of an additive characterized by this further improves chemical resistance and organic solvent resistance. In particular, silicon oxide, calcium carbonate, zinc, red lead, lead suboxide, zinc oxide, lead cyanamide, zinc chromate, potassium barium chromate, barium zinc chromate, etc. are generated by the reaction of electrolyte with moisture Has the effect of preventing hydrogen fluoride from corroding each layer, particularly the metal foil layer.

  In addition, when using the extrusion laminating method, polyester, polyether, urethane, polyetherurethane, polyesterurethane, isocyanate, and polyolefin can be used as an adhesion promotion method that stabilizes the adhesive strength between the layers to be bonded. Applying resin such as polyethyleneimine, cyanoarylate, organotitanium compound, epoxy, imide, silicone, and their modified products or mixtures, about 1μm, or surface activation treatment by ozone treatment It can be carried out. Further, by using an unsaturated carboxylic acid grafted polyolefin as a resin when bonded by an extrusion laminating method or a thermal laminating method, adhesion resistance and content resistance are improved.

  The heat-resistant resin layer 10 laminated on the exterior body 5 has a higher melting point and glass transition point than the heat-adhesive resin layer 11, so that the periphery of the exterior body is sandwiched between the tabs 4 protruding from the battery body 2. When heat-bonding, the heat-adhesive resin layer 11 which is the inner layer of the exterior body is extruded out of the pressurizing part by heat and pressure, and the pressurizing part becomes thin, but the heat-resistant resin layer 10 is thin-walled. Since it remains without becoming, it can prevent that the metal foil layer 8 and the tab 4 of an exterior body short-circuit. The material of the heat resistant resin layer 10 is higher in melting point and glass transition point than the general polyolefin resin forming the heat-adhesive resin layer 11 and the acid-modified polyolefin resin forming the acid-modified polyolefin layer. An excellent biaxially stretched polyethylene naphthalate film (hereinafter referred to as PEN) is preferred. Hereinafter, the case where the heat resistant resin layer 10 is PEN will be described.

  Since PEN is superior in water vapor barrier properties (small water vapor permeability) compared to the PET, water vapor can be prevented from entering the lithium battery, and the battery life can be made as designed. As thickness when using PEN as the heat resistant resin layer 10, 6 micrometers or more are required, Preferably it is 12-25 micrometers. If it is less than 6 μm, there is a possibility of short circuit, and if it exceeds 25 μm, no significant improvement effect is seen in cost effectiveness (short circuit prevention effect). Moreover, well-known easy-adhesion means such as corona discharge treatment, ozone treatment, and plasma treatment can be taken on the surface of PEN as required.

  Next, the adhesion promoter layer 16 will be described. The adhesion promoter layer 16 is provided for the purpose of firmly bonding the PEN 18 and the acid-modified polyolefin layer 17 and uses a known adhesion promoter such as isocyanate, polyethyleneimine, polyester, polyurethane, and polybutadiene. However, as a result of the experiment, those composed of an isocyanate component selected from a triisocyanate monomer and polymeric MDI were excellent in laminate strength, and there was little decrease in laminate strength after immersion in an electrolyte solution.

  In particular, it is composed of triisocyanate monomer triphenylmethane-4,4 ′, 4 ″ -triisocyanate and polymeric MDI polymethylene polyphenyl polyisocyanate (NCO content is about 30%, viscosity is 200 to 700 mPa · s). The best results were obtained when an adhesion promoter was used, followed by cross-linking of polycarbodiimide using tris (p-isocyanatephenyl) thiophosphate, which is also a triisocyanate monomer, and polyethyleneimine. The two-part curable adhesion promoter used as an agent showed good results.

The adhesion promoter layer 16 can be formed by coating and drying by a known coating method such as a bar coating method, a roll coating method, or a gravure coating method. The coating amount is an adhesion made of triisocyanate. In the case of an accelerator, it is 20 to 100 mg / m ² , preferably 40 to 60 mg / m ² , and in the case of an adhesion promoter made of polymeric MDI, 40 to 150 mg / m ² , preferably 60 to 100 mg / m ² , and the a main component of polyethylene imine, a two-liquid curing type adhesion promoter which is the polycarbodiimide crosslinking agent, 5 to 50 mg / m ^2, preferably 10 to 30 mg / m ^2. The triisocyanate monomer is a monomer having three isocyanate groups in one molecule. Polymeric MDI is a mixture of MDI and MDI oligomer obtained by polymerization of MDI, and is represented by the following formula (1).

In addition, the adhesion promoter layer 16 can be formed using an amination phenol polymer, a trivalent chromium compound, and an adhesion promoter containing a phosphorus compound. It can be formed by coating and drying by a known coating method such as a roll coating method or a gravure coating method. First, the aminated phenol polymer will be described. A well-known thing can be widely used as an aminated phenol polymer, for example, aminated phenol heavy which consists of a repeating unit represented by following formula (2), (3), (4), (5). Coalescence can be mentioned. X in the formula represents a hydrogen atom, a hydroxyl group, an alkyl group, a hydroxyalkyl group, an allyl group or a benzyl group. R ₁ and R ₂ represent a hydroxyl group, an alkyl group, or a hydroxyalkyl group, and may be the same group or different groups.

In the following formulas (2) to (5), examples of the alkyl group represented by X, R ₁ and R ₂ include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, C1-C4 linear or branched alkyl groups, such as a tert- butyl group, can be mentioned. Examples of the hydroxyalkyl group represented by X, R ₁ and R ₂ include a hydroxymethyl group, a 1-hydroxyethyl group, a 2-hydroxyethyl group, a 1-hydroxypropyl group, a 2-hydroxypropyl group, 3- C1-C4 straight or branched chain in which one hydroxy group such as hydroxypropyl group, 1-hydroxybutyl group, 2-hydroxybutyl group, 3-hydroxybutyl group, 4-hydroxybutyl group is substituted An alkyl group can be mentioned. X in the following formulas (2) to (5) is preferably any of a hydrogen atom, a hydroxyl group, and a hydroxyalkyl group.

Further, the aminated phenol polymer represented by the following formulas (2) and (4) is an aminated phenol containing about 80 mol% or less of repeating units, preferably about 25 to about 55 mol% of repeating units. It is a polymer. The number average molecular weight of the aminated phenol polymer is preferably about 500 to about 1 million, more preferably about 1000 to about 20,000. The aminated phenol polymer is produced by, for example, polycondensing a phenol compound or naphthol compound and formaldehyde to produce a polymer composed of repeating units represented by the following formulas (2) to (4). Is prepared by introducing a water-soluble functional group (—CH ₂ NR ₁ R ₂ ) using formaldehyde and amine (R ₁ R ₂ NH). The aminated phenol polymer can be used singly or in combination of two or more.

  Next, the trivalent chromium compound will be described. As the trivalent chromium compound, known compounds can be widely used. For example, chromium nitrate, chromium fluoride, chromium sulfate, chromium acetate, chromium oxalate, chromium biphosphate, chromic acetyl acetate, chromium chloride, sulfuric acid Potassium chromium etc. can be mentioned, Preferably they are chromium nitrate and chromium fluoride.

  Next, a phosphorus compound is demonstrated. As a phosphorus compound, a well-known thing can be used widely, For example, condensed phosphoric acids, such as phosphoric acid and polyphosphoric acid, these salts, etc. can be mentioned. Here, as said salt, alkali metal salts, such as ammonium salt, sodium salt, potassium salt, can be mentioned, for example.

And as said adhesion promoter layer 16 formed using the adhesion promoter containing an aminated phenol polymer, a trivalent chromium compound, and a phosphorus compound, the amination phenol polymer is about 1 to 1 m ² . It is appropriate that about 200 mg, the trivalent chromium compound is contained in a proportion of about 0.5 to about 50 mg in terms of chromium, and the phosphorus compound is contained in a proportion of about 0.5 to about 50 mg in terms of phosphorus. More than about 5 to about 150 mg of polymer, about 1.0 to about 40 mg of trivalent chromium compound in terms of chromium, and about 1.0 to about 40 mg in terms of phosphorus are more contained. preferable. In this case, the drying temperature is 150 to 250 ° C., preferably 170 to 250 ° C., and it is appropriate to perform heat treatment (baking). Further, when the post-heating treatment is performed at a temperature exceeding the softening point of the resin constituting the acid-modified polyolefin layer 17 after forming the laminated structure, the interlayer adhesive strength can be remarkably improved.

  In the case of the adhesion promoter layer 16 containing an aminated phenol polymer, a trivalent chromium compound, and a phosphorus compound, the adhesion promoter layer 16 and the acid-modified polyolefin layer 17 in the laminated structure shown in FIG. An adhesion promoter layer composed of the isocyanate component described above may be provided between these layers. By comprising in this way, interlayer adhesive strength can be improved significantly, without performing the above-mentioned post-heating process.

  The acid-modified polyolefin layer 17 is a polyolefin resin graft-modified with an unsaturated carboxylic acid, a copolymer of ethylene or propylene and acrylic acid, or methacrylic acid, or a metal-crosslinked polyolefin resin. Components, ethylene-propylene-butene copolymer, amorphous ethylene-propylene copolymer, propylene-α-olefin copolymer and the like may be added in an amount of 5% or more.

  The acid-modified polyolefin layer 17 is formed by heat-melting and extruding the acid-modified polyolefin resin from the T-die extruder onto the PEN 18 on which the adhesion promoter layer 16 is formed. For the purpose of improving the adhesion between the accelerator layer 16 and the acid-modified polyolefin layer 17, it is necessary for the surface of the acid-modified polyolefin resin that is heated and melt-extruded from a T-die extruder to contact the adhesion promoter layer 16. Depending on the case, ozone treatment may be applied.

  In particular, when the adhesion promoter layer 16 is an isocyanate type, the laminate strength is remarkably improved by performing the ozone treatment. The acid-modified polyolefin layer 17 has a thickness of 10 μm or more, preferably 20 to 50 μm. If the thickness is less than 10 μm, a sufficient laminate strength cannot be obtained because the heat quantity of the extruded molten resin is insufficient. As a result, a sufficient seal strength cannot be obtained, and if it exceeds 50 μm, the total thickness of the adhesive film increases, As a result, the water vapor barrier property is reduced and no significant improvement in cost effectiveness (laminate strength, seal strength) is observed.

  Moreover, at least the layer on the battery tab 4 side of the acid-modified polyolefin layer 17 can be a filler-containing layer containing a filler. By using the layer containing the filler as described above, the filler functions as a spacer, so that a short circuit between the metal foil layer of the outer package and the metal terminal, in particular, the burr of the metal terminal is further prevented. be able to.

  The average particle diameter of the filler is in the range of 0.1 to 35 μm, preferably 5.0 to 30 μm, more preferably 10 to 25 μm, and the content thereof is 100 parts by mass of acid-modified polyolefin resin. It is 5-30 mass parts with respect to this, Preferably it is 10-20 mass parts. The reason for this is that when the average particle size of the filler is less than 0.1 μm, the filler metal must be contained in an amount of more than 30 parts by weight with respect to 100 parts by weight of the acid-modified polyolefin resin forming the filler-containing layer. When the foil layer and the burr of the battery tab cannot be prevented from being short-circuited, there is a problem that sufficient adhesion strength with the battery tab cannot be obtained, and the average particle size of the filler is over 35 μm. Even if the content of the filler is adjusted to more than 0 and less than 5 parts by mass with respect to 100 parts by mass of the acid-modified polyolefin resin forming the filler-containing layer, short circuit between the metal foil layer of the outer package and the burr of the battery tab is prevented. This is because the problem that it cannot be prevented and the problem that sufficient adhesive strength with the metal terminal cannot be obtained arise.

  As the filler, both inorganic and organic can be used. Examples of the inorganic filler include carbon (carbon, graphite), silica, aluminum oxide, barium titanate, iron oxide, silicon carbide, Zirconium oxide, zirconium silicate, magnesium oxide, titanium oxide, calcium aluminate, calcium hydroxide, aluminum hydroxide, magnesium hydroxide, calcium carbonate and the like can be mentioned. Examples of organic fillers include fluororesin, phenol Resin, urea resin, epoxy resin, acrylic resin, benzoguanamine / formaldehyde condensate, melamine / formaldehyde condensate, polymethyl methacrylate cross-linked product, polyethylene cross-linked product, etc., but shape stability, rigidity, contents From the point of tolerance Aluminum, silica, fluorine resin, acrylic resin, preferably benzoguanamine-formaldehyde condensates, in particular aluminum oxide spherical Among these, silica is more preferable. As a method of mixing the filler into the acid-modified polyolefin resin, a method of melt-blending both with a Banbury mixer in advance and making a master batch into a predetermined mixing ratio, or direct mixing with the acid-modified polyolefin resin Any of the methods may be used.

  The acid-modified polyolefin layer 17 may be a colored layer by adding a pigment as necessary. As the pigment used for this, various inorganic pigments can be used, but it is a material generally used in the inside of the battery, there is no fear of elution with respect to the electrolytic solution, and the coloring effect is large and the adhesiveness is high. A sufficient coloring effect can be obtained with an addition amount that does not hinder, and the apparent melt viscosity of the added resin can be increased without melting by heat, and the pressure part is thin during thermal bonding (sealing) For example, carbon (carbon, graphite) exemplified as the filler is preferable, and for example, the average particle size is about 0. When 0.03 μm carbon black is used, it is 0.05 to 0.3 parts by weight, preferably 0.1 to 0.2 parts by weight, based on 100 parts by weight of the resin. Thus, by using the heat seal layer as a colored layer, the presence or absence of the adhesive film 4b can be detected by a sensor, or can be visually inspected. The filler-containing layer and the colored layer may be the same acid-modified polyolefin layer, but different acid-modified polyolefin layers are preferable from the viewpoint of not inhibiting the thermal adhesiveness of the acid-modified polyolefin layer 17. .

  Furthermore, in consideration of flatness and convenience, the acid-modified polyolefin layers on both sides of the PEN 18 are preferably formed with the same resin and the same thickness.

Next, the packaging method will be specifically described with reference to the drawings. FIG. 7 is a view showing an embodiment of a packaging method using a battery according to the present invention in a pouch type, (a) a perspective view showing the battery, (b) an arrow view from G (part) (c) X ₂ − X ₂ parts folded before cross-sectional view, a cross-sectional view after (d) folding. FIG. 8 is a view showing another embodiment of the battery packaging method of the present invention, (a) a perspective view showing the battery body, (b) an arrow view from G (part) (c) X ₃ -X _It is sectional drawing before a ₃ part folding | turning, (d) It is sectional drawing after folding.

  First, a multilayer having a structure in which at least a base material layer, a metal foil layer provided with a chemical conversion treatment layer on at least a surface on the housing side, an acid-modified polyolefin layer, a heat-resistant resin layer, and a heat-adhesive resin layer are laminated in this order. A battery outer body characterized by being a film is prepared. Next, when packaging the battery to be sealed by housing the battery main body in the exterior body and facing the heat-adhesive resin layers of the exterior body to each other and heat-sealing the periphery including the lead wire portion, FIG. c) As shown in c), both the laminated bodies on the sides to be heat-sealed by sandwiching the battery tab are extended to form an extended end portion 20, and one or both outer end portions of the extended end portion 20 are folded back and folded. By deforming and holding the exterior body in a state, a short circuit due to contact between the metal foil layer cross section 8 and the battery tab 4 can be prevented.

  Further, the folding back of the extended end portion may be performed on both sides as shown in FIG. 7 (d) or only on one side as shown in FIG. 8 (d). In addition, in the case of only one side, the extended end portion 20 that is not folded back needs to be longer than the battery tab 4 so as not to contact the battery tab 4 of the battery.

  In the packaging method of the present invention, the laminated body at the side that is heat-sealed with the battery tab 4 interposed therebetween is extended to form an extended end portion 20, and the extended end portion 20 is folded outward and remains in its folded state. In order to deform and hold the exterior body, it is preferable that the laminated body of the exterior body includes at least a layer of a material having a certain hardness and capable of retaining the deformed state. Specifically, by using an aluminum layer for the metal foil layer, the exterior body can be deformed and held. In addition, after the extended end portion 20 is folded, an adhesive is applied to the opposing surfaces of the folded portions to bond the base material layers together, or the surface layer of the base material layer 7 of the exterior body is made of crosslinked polyolefin by heat sealing. It is also possible to bond.

The lithium ion battery in which the battery main body is sealed by the battery outer package and the packaging method of the present invention will be described with reference to examples. The implementation conditions are as follows.
(1) The tabs were made of nickel as the anode and aluminum as the cathode, all of which had a width of 8 mm, a length of 50 mm, a thickness of 100 μm, and a length of 10 mm from the end face which is a folded portion or a cross section of the exterior body.
(2) The exterior body was a pillow type, the pouch size was an external size, a width of 60 mm, and a length of 80 mm (both seal widths were 5 mm).
(3) The structure of the laminate A used as an outer package is a stretched polyester film 20 μm / aluminum 20 μm / acid-modified polyethylene resin (unsaturated carboxylic acid grafted polyethylene 20 μm) / biaxially stretched polyethylene naphthalate film 12 μm / maleic acid-modified polypropylene 20 μm. (Numerical values indicate layer thickness μm).
(4) Chemical conversion treatment was performed on both surfaces of the aluminum foil. In each of the chemical conversion treatments, an aqueous solution composed of a phenol resin, a chromium fluoride (3) compound, and phosphoric acid was applied as a treatment liquid by a roll coating method, and baked under a condition that the film temperature was 180 ° C. or higher. The application amount of chromium is 10 mg / m ² (dry weight).

  The battery body was housed in the exterior body, the end of the exterior body was folded back to both sides, folded back 4 mm by thermal bonding, and hermetically sealed.

  Using the lithium ion battery obtained in the example, the battery tab was bent and pressed against the end face of the exterior body, and repeated charging and discharging over a long period of time, electrolyte leakage or short circuit between the battery tab and the exterior body In addition, the sealing property of the outer package at the pinched portion of the tab was good.

  TECHNICAL FIELD The present invention relates to a battery exterior body, a battery packaging method, and a battery using the same, which can be used for a large-sized battery having high durability and safety, which is suitable as a power source for energy storage and electric vehicles. .

  As described above, the battery exterior body and packaging method according to the present invention can provide a high-performance battery excellent in durability and manufacturing efficiency.

These are the perspective view and exploded perspective view of the lithium ion battery (pouch type) of the present invention. These are the perspective view and exploded perspective view of the lithium ion battery (emboss type) of the present invention. These are sectional drawings which show the laminated structure of the exterior body used for this invention. These are sectional drawings which show a laminated structure in case the heat resistant resin layer of the exterior body used for this invention is a biaxially-stretched polyethylene naphthalate film, and an acid-modified polyolefin layer consists of acid-modified polypropylene. It is a diagram showing a short circuit state between the barrier layer and the cell tabs in a conventional outer package, (a) a perspective view showing a battery main body, (b) arrow view from G (c) X ₁ -X ₁ part (D) It is a conceptual sectional view showing the moment of short-circuiting. These are sectional drawing of the lead wire part explaining the prior art which prevents a short circuit. Is a diagram showing an embodiment of a method of packaging batteries in a pouch type, (a) a perspective view showing a battery main body, (b) arrow view from G (c) X ₂ -X ₂ parts folded before cross FIG. 4D is a sectional view after folding. Is a diagram showing an embodiment of a method of packaging batteries, (a) a perspective view showing a battery main body, (b) arrow view from _{G, (c) X 3 -X} 3 parts folded before cross-sectional view, ( d) It is sectional drawing after folding.

Explanation of symbols

1 Battery 2 Battery Body 3 Cell (Power Storage Unit)
4 Tab 5 Exterior Body 6 Laminate 7 Base Material Layer 8 Metal Foil Layer 9 Acid Modified Polyolefin Layer 10 Heat Resistant Resin Layer 11 Thermal Adhesive Resin Layer 12 Acid Modified Polyolefin Layer (Thermoadhesive Resin Layer)
DESCRIPTION OF SYMBOLS 13 Polyolefin layer 14 Adhesive layer 15 Chemical conversion treatment layer 16 Adhesion promoter layer 17 Acid-modified polypropylene 18 Biaxially stretched polyethylene naphthalate film 19 Heat seal part 20 Extension end part 20S Folding seal part 21 Short part 22 Adhesion for battery metal terminal part sealing Sex film

Claims (8)

A battery body including a positive electrode composed of a positive electrode active material and a positive electrode current collector, a negative electrode composed of a negative electrode active material and a negative electrode current collector, and an electrolyte filled between the positive electrode and the negative electrode;
A battery exterior body that seals the battery body by heat-sealing a peripheral edge,
A multilayer film having a structure in which at least a base material layer, a metal foil layer provided with a chemical conversion treatment layer on at least a surface on the housing side, an acid-modified polyolefin layer, a heat-resistant resin layer, and a heat-adhesive resin layer are laminated in this order. der is, the heat-adhesive resin layer, outer package for a battery, characterized in that comprising the heat-resistant acid-modified polyolefin layer disposed on the resin layer side and the polyolefin layer disposed innermost layer side.   The battery exterior body according to claim 1, wherein the heat-resistant resin layer has a melting point of 200 ° C. or higher. The battery exterior body according to claim 1 or 2, wherein an adhesive layer is provided between the heat resistant resin layer and the acid-modified polyolefin layer . The battery exterior according to any one of claims 1 to 3, wherein the heat resistant resin layer is made of a biaxially stretched polyethylene naphthalate film, and the acid-modified polyolefin layer is made of acid-modified polypropylene. body. The battery for battery according to claim 4 , wherein an adhesion promoter containing an aminated phenol polymer, a trivalent chromium compound, and a phosphorus compound is formed on both surfaces of the biaxially stretched polyethylene naphthalate film . Exterior body. A battery body including a positive electrode composed of a positive electrode active material and a positive electrode current collector, a negative electrode composed of a negative electrode active material and a negative electrode current collector, and an electrolyte filled between the positive electrode and the negative electrode,
A battery, wherein the battery is sealed in the battery outer package according to any one of claims 1 to 5. The package which seals the said battery main body by accommodating the said battery main body in the battery exterior body in any one of Claim 1 to Claim 6, facing the said thermoadhesive resin layers, and heat-sealing a periphery. In this case, the outer side of the side to be heat-sealed with the battery tab sandwiched is extended to be an extended end, and at least one outer end of the extended end is folded back, and the outer package is deformed and held in the folded state. A battery packaging method characterized by comprising: The battery according to claim 7, wherein the battery body is hermetically sealed with the battery exterior body.

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