JP6987113B2 - Laminate for exterior non-aqueous batteries - Google Patents

Description

The present invention relates to a non-aqueous battery exterior laminate used for a secondary battery such as a lithium ion battery and an exterior material such as an electric double layer capacitor.

In recent years, with the rise of global environmental problems, the spread of electric vehicles and the effective utilization of natural energy such as wind power generation and solar power generation have become issues. Along with this, in these technical fields, secondary batteries such as lithium ion batteries and electric double layer capacitors are attracting attention as storage batteries for storing electric energy.
As an exterior container for storing a lithium-ion battery used in an electric vehicle or the like, a container made of a battery exterior laminate in which a metal foil and a resin layer are laminated is used in order to reduce the size and weight (in order to reduce the size and weight). For example, see Patent Document 1).

To manufacture a secondary battery using the exterior container manufactured by using the battery exterior laminate described above, for example, the following is performed.
The battery exterior laminate is formed into a tray shape with recesses by drawing or the like to form a container body. Batteries are stored in the recesses of the container body. Next, the battery was housed in the outer container by stacking the lid material made of the battery exterior laminate on the container body and heat-sealing the flange portion of the container body and the side edge portion of the lid material. Get the next battery.

Japanese Unexamined Patent Publication No. 2000-357494

In recent years, in applications such as storage batteries for electric vehicles, exterior containers for large batteries with larger external dimensions and exterior containers that can increase the internal volume by reducing the thickness of the battery exterior laminate have become available. It has been demanded. However, in the case of an exterior container for a large battery, it is necessary to form a container body having a deeper recess, which increases technical difficulty. For example, if the battery exterior laminate is deeply drawn and molded, the metal foil and the resin layer may be peeled off, and the battery exterior laminate may be damaged (torn or the like). Further, if the thickness of the battery exterior laminate is reduced, there arises a problem that mechanical strength such as piercing strength is lowered.
Therefore, it has been desired to increase the mechanical strength of the battery exterior laminate, reduce the occurrence of defects during drawing molding, and increase the manufacturing yield of the non-aqueous battery.

The present invention has been made in view of the above circumstances, and improves the production efficiency of the non-aqueous battery by increasing the mechanical strength of the non-aqueous battery exterior laminate and preventing the occurrence of defects during drawing molding. It is an object of the present invention to provide a laminate for exterior of a non-aqueous battery which can be used.

In order to solve the above problems, in the present invention, the SUS foil and the sealant layer are laminated, and the SUS foil contains a water-soluble resin and a fluorometal compound at least on the sealant layer side. A surface coating layer having a thickness of 0.05 μm to 1.0 μm is formed by drying and curing the paint, and urethane resin, acrylic resin, and poly are formed on the surface side of the SUS foil opposite to the sealant layer side. Vinylidene chloride, vinylidene chloride-vinyl chloride copolymer resin, maleic anhydride-modified polypropylene resin, polyester resin, epoxy resin, phenol resin, phenoxy resin, fluororesin, cellulose ester resin, cellulose ether resin, polyamide resin, polyphenylene ether resin, polyphenylene Provided is a non-aqueous battery exterior laminate having a coating layer formed of at least one resin selected from the resin group consisting of a sulfide resin, a polyvinylidene resin, and a polyether ether ketone resin.
The coating layer is preferably a thin film cured layer formed by applying and drying a solvent-type paint prepared by dissolving the resin in an organic solvent.
The coating layer is preferably colored with an achromatic or chromatic colorant.
The water-soluble paint preferably further contains an organic chelating agent.
The fluorometal compound is preferably a substance that crosslinks the water-soluble resin and passivates the surface of the SUS foil.

According to the present invention, since the resin coating layer is formed on one side of the SUS foil, the mechanical strength and slipperiness of the battery exterior laminate can be increased. Since the resin coating layer is formed by coating, it is firmly bonded to the SUS foil.
In general, SUS foil is inferior in processability to other metal foils such as aluminum foil, so it is difficult to set conditions when deep drawing is performed, and peeling from adjacent layers is likely to occur.
On the other hand, in the present invention, the resin coating layer is firmly bonded to the SUS foil, so that peeling can be prevented. Further, since the mechanical strength and slipperiness are enhanced by the resin coating layer, it is possible to reduce damage (tear, etc.) and deformation of the battery exterior laminate when the recess is formed by drawing molding.
Therefore, even when deep drawing molding is performed, it is possible to prevent a decrease in battery production efficiency due to molding defects in the battery outer container. In addition, since the battery exterior laminate is less likely to be damaged, it is possible to prevent deterioration of battery performance and ignition due to leakage of electrolytic solution and infiltration of water.
In the present invention, the formation of the resin coating layer can prevent the surface of the battery exterior laminate from being damaged by an external force. Further, even when the battery exterior laminate comes into contact with the electrolytic solution, it is possible to prevent a change in appearance (discoloration or the like).
Since the coating layer is formed by coating, the battery exterior laminate can be formed thinner than when the resin film is laminated via an adhesive. Therefore, the battery outer container can be made thinner, the internal volume can be increased, and the volumetric efficiency of the battery can be improved.

It is a schematic sectional drawing which shows 1st Embodiment of the laminated body for the exterior of a non-aqueous battery which concerns on this invention. It is a perspective view which shows an example of the secondary battery manufactured using the laminated body for the exterior of the non-aqueous battery of FIG. It is a perspective view which shows the process of manufacturing the secondary battery of the preceding figure. It is a schematic sectional drawing which shows the 2nd Embodiment of the laminated body for the exterior of a non-aqueous battery which concerns on this invention. It is the schematic sectional drawing which shows the 1st modification of the laminated body for battery exterior shown in FIG. 1. It is the schematic sectional drawing which shows the 2nd modification of the laminated body for battery exterior shown in FIG. 1. FIG. 3 is a schematic cross-sectional view showing a third modification of the battery exterior laminate shown in FIG. 1.

FIG. 1 shows the battery exterior laminate 10 according to the first embodiment of the non-aqueous battery exterior laminate (hereinafter, may be simply referred to as a battery exterior laminate) according to the present invention. Further, FIG. 2 shows a non-aqueous battery exterior container 20 for a lithium ion battery manufactured by using the battery exterior laminate 10 according to the present invention (hereinafter, may be simply referred to as a battery exterior container 20), and 2 The next battery 40 is shown.

FIG. 2 shows a perspective view of a secondary battery 40 using the battery exterior container 20 which is an example of the battery exterior container of the present invention. The secondary battery 40 is a battery exterior container 20 containing a lithium ion battery 27.
In the battery exterior container 20, the container body 30 made of the battery exterior laminate 10 according to the first embodiment of the battery exterior laminate 10 of the present invention and the lid material 33 made of the battery exterior laminate 10 are stacked. It is formed by heat-sealing the peripheral edge portion 29. Reference numeral 28 is an electrode lead connected to the positive electrode and the negative electrode of the lithium ion battery 27.

As shown in FIG. 1, the battery exterior laminate 10 according to the present invention has a structure in which a SUS foil 12 and a sealant layer 13 are laminated, and the surface of the SUS foil 12 opposite to the sealant layer 13. A coating layer 16 (first coating layer) is provided on the side (upper surface side in FIG. 1).
In the present specification, the SUS foil means a metal foil made of stainless steel.
A print layer 15 (second coating layer) is formed between the SUS foil 12 and the coating layer 16.
Surface coating layers 17 and 18 are formed on the sealant layer 13 side (lower surface side in FIG. 1) and the coating layer 16 side (upper surface side in FIG. 1) of the SUS foil 12, respectively.
The battery exterior laminate 10 has a print layer 15, but the print layer 15 may not be present.

Hereinafter, each layer will be described in detail.
The SUS foil 12 is a metal foil made of stainless steel, and is made of, for example, stainless steel such as austenite-based, ferritic-based, and martensitic-based. The austenitic stainless steel includes SUS304, 316, 301 and the like, the ferrite type includes SUS430 and the like, and the martensitic stainless steel includes SUS410 and the like. Since the SUS foil 12 has higher mechanical strength such as tensile strength than other metal foils such as aluminum foil, it reduces the occurrence of pinholes when forming recesses by drawing and prevents liquid leakage from the battery. It can be less likely to occur. Further, since the SUS foil 12 is superior in corrosion resistance to other metal foils, deterioration due to corrosion is unlikely to occur.

The thickness of the SUS foil 12 can be, for example, 5 μm to 100 μm. The thickness of the SUS foil 12 is preferably 5 μm to 50 μm. By setting the thickness of the SUS foil 12 to 5 μm or more, sufficient strength (piercing strength, etc.) can be given to the battery exterior laminate 10 and the durability of the secondary battery 40 can be enhanced. Further, by setting the thickness of the SUS foil 12 to 50 μm or less, sufficient drawing workability can be imparted to the battery exterior laminate 10.

The surface coating layers 17 and 18 are layers formed by drying and curing a water-soluble paint containing a water-soluble resin and a fluorometal compound. The water-soluble paint preferably contains an organic chelating agent.

The thicknesses of the surface coating layers 17 and 18 are 0.05 μm or more (preferably more than 0.2 μm), respectively. By setting the thickness of the surface coating layers 17 and 18 to 0.05 μm or more, sufficient corrosion resistance is given to the battery exterior laminate 10, the adhesive strength between the SUS foil 12 and the sealant layer 13, and the SUS. The adhesive strength between the foil 12 and the layer on the upper layer side thereof can be increased. The thickness of the surface coating layers 17 and 18 is 1.0 μm or less (preferably 0.5 μm or less). By setting the thickness of the surface coating layers 17 and 18 to 1.0 μm or less, the adhesive strength between the SUS foil 12 and the sealant layer 13 can be increased, and the material cost can be suppressed. The thickness of the surface coating layers 17 and 18 is preferably in the range of more than 0.2 μm and 0.5 μm or less.

As the water-soluble resin, it is preferable to use one or more of a polyvinyl alcohol-based resin and a polyvinyl ether-based resin. The polyvinyl alcohol-based resin is at least one water-soluble resin selected from a polyvinyl alcohol resin and a modified polyvinyl alcohol resin. The polyvinyl alcohol-based resin can be produced, for example, by saponifying a polymer of a vinyl ester-based monomer or a copolymer thereof. The polymer of the vinyl ester-based monomer or its copolymer may be a homopolymer of a fatty acid vinyl ester such as vinyl formate, vinyl acetate, vinyl butyrate, or a homopolymer of a vinyl ester-based monomer such as an aromatic vinyl ester such as vinyl benzoate. Examples thereof include a copolymer and a copolymer of another monomer copolymerizable therewith.
Examples of other copolymerizable monomers include olefins such as ethylene and propylene, ether group-containing monomers such as alkyl vinyl ether, carbonyl groups such as diacetone acrylamide, diacetone (meth) acrylate, allyl acetoacetate, and acetoacetic acid ester. Examples thereof include (ketone group) -containing monomers, unsaturated carboxylic acids such as acrylic acid, methacrylic acid and maleic anhydride, vinyl halides such as vinyl chloride and vinylidene chloride, and unsaturated sulfonic acids.
The saponification degree of the polyvinyl alcohol-based resin is usually preferably 90 to 100 mol%, more preferably 95 mol% or more.

Examples of the polyvinyl alcohol-based resin that can be used in the present invention include alkyl ether-modified polyvinyl alcohol resin, carbonyl-modified polyvinyl alcohol resin, acetacetyl-modified polyvinyl alcohol resin, acetamide-modified polyvinyl alcohol resin, acrylic nitrile-modified polyvinyl alcohol resin, and carboxyl-modified polyvinyl alcohol resin. , Silicone-modified polyvinyl alcohol resin, ethylene-modified polyvinyl alcohol resin and the like. Among them, alkyl ether-modified polyvinyl alcohol resin, carbonyl-modified polyvinyl alcohol resin, carboxyl-modified polyvinyl alcohol resin, and acetoacetyl-modified polyvinyl alcohol resin are preferable.
Commercially available polyvinyl alcohol-based resins include, for example, J-Poval DF-20 (trade name) manufactured by Japan Vam & Poval Co., Ltd. and Crosmer H series manufactured by Nippon Carbide Industries Co., Ltd. ( Product name) and so on. As the polyvinyl alcohol-based resin, one kind or a mixture of two or more kinds may be used.

Examples of the polyvinyl ether-based resin include ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexyl vinyl ether, norbornenyl vinyl ether, allyl vinyl ether, norbornenyl vinyl ether, and 2-hydroxyl. Examples thereof include homopolymers or copolymers of aliphatic vinyl ethers such as ethyl vinyl ether and diethylene glycol monovinyl ether, and copolymers of other monomers copolymerizable therewith. Examples of the other monomer copolymerizable with the vinyl ether-based monomer include those similar to the other monomers copolymerizable with the vinyl ester-based monomer described above.

In particular, polyvinyl ether-based resins containing a hydroxyl group aliphatic vinyl ether as a monomer, such as 2-hydroxyethyl vinyl ether, diethylene glycol monovinyl ether, 2-hydroxypropyl vinyl ether, and other glycols and monovinyl ethers of polyhydric alcohols, are water-soluble. And since it is capable of a cross-linking reaction with a hydroxyl group, it can be suitably used in the present invention.
Since the vinyl ether monomer can be used in the resin production (polymerization) step, these polyvinyl ether-based resins undergo a saponification treatment unlike the polyvinyl alcohol-based resins produced via the vinyl ester-based polymer. It can be manufactured without any problems. Further, a copolymer containing a vinyl ester-based monomer and a vinyl ether-based monomer, or a vinyl alcohol-vinyl ether copolymer obtained by saponifying the copolymer can also be used. A mixture of a polyvinyl alcohol-based resin other than the polyvinyl ether-based resin and a polyvinyl ether-based resin can also be used.

As the water-soluble resin, only one of the polyvinyl alcohol-based resin and the polyvinyl ether-based resin may be used, or both may be used in combination.

The fluorometal compound is preferably water-soluble because it needs to be mixed with the above-mentioned water-soluble resin. Specific examples of the metal fluoride compound include chromium fluoride, iron fluoride, zirconium fluoride, titanium fluoride, hafnium fluoride, titanium hydrofluoric acid, and salts thereof. The fluorometal compound has an action of improving the electrolytic solution resistance performance. That is, the surface of the SUS foil 12 can be passivated and the corrosion resistance to the electrolytic solution can be improved. The fluorometal compound also has an action of cross-linking the water-soluble resin.

The organic chelating agent is an organic substance that can chemically bond with cations to form a metal ion complex. The organic chelating agent binds a metal compound derived from a metal fluoride compound (chromium oxide, etc.) and the water-soluble resin to increase the compressive strength of the surface coating layers 17 and 18, so that the surface coating layers 17 and 18 are combined. Even when the thickness of the above is, for example, more than 0.2 μm and 1.0 μm or less, the surface coating layer does not become brittle and crack or peeling does not occur. Therefore, the adhesive strength between the SUS foil 12 and the sealant layer 13 and the adhesive strength between the SUS foil 12 and the layer on the upper layer side thereof can be increased. Further, the organic chelating agent has an action of making the water-soluble resin water-resistant by chemically reacting with the water-soluble resin or the fluorometal compound.

As the organic chelating agent, for example, an aminocarboxylic acid-based chelating agent, a phosphonic acid-based chelating agent, an oxycarboxylic acid-based chelating agent, and a (poly) phosphoric acid-based chelating agent can be used. Examples of the aminocarboxylic acid-based chelating agent include nitrilotriacetic acid (NTA), hydroxyethyliminodiacetic acid (HIDA), ethylenediaminetetraacetic acid (EDTA), hydroxyethylethylenediaminetriacetic acid (HEDTA), diethylenetriaminepentaacetic acid (DTPA), and the like. Triethylenetetramine hexaacetic acid (TTHA), transcyclohexanediamine tetraacetic acid (CyDTA), 1,2-propanediamine tetraacetic acid (1,2-PDTA), 1,3-propanediamine tetraacetic acid (1,3-PDTA), 1,4-Butandiamine tetraacetic acid (1,4-BDTA), 1,3-diamino-2-hydroxypropanetetraacetic acid (DPTA-OH), glycol etherdiaminetetraacetic acid (GEDTA), ethylenediamine orthohydroxyphenylacetic acid (EDHPA) ), SS-ethylenediamine disuccinic acid (SS-EDDS), ethylenediamine disuccinic acid (EDDS), β-alanine diacetic acid (ADA), methylglycine diacetic acid (MGDA), L-aspartic acid-N, N-diacetic acid. (ASDA), L-glutamate-N, N-diacetic acid (GLDA), N, N'-bis (2-hydroxybenzyl) ethylenediamine-N, N'-diacetic acid (HBEDDA).
Examples of the phosphonic acid-based chelating agent include N, N, N-trimethylenephosphonic acid (NTMP), 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP), ethylenediamine-N, N, N', N'. -Tetramethylenephosphonic acid (EDTMP), diethylenetriaminepentamethylenephosphonic acid (DTPMP), 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC) can be mentioned.
Examples of the oxycarboxylic acid-based chelating agent include glycolic acid, citric acid, malic acid, gluconic acid, and glucoheptonic acid.
Examples of the (poly) phosphoric acid-based chelating agent include metaphosphoric acid, tripolyphosphoric acid, tetrapolyphosphoric acid, pyrophosphoric acid, orthophosphoric acid, hexametaphosphoric acid, and salts thereof.
Examples of commercially available organic chelating agents that are generally available include Kirest PD-4H (trade name) (PDTA) and Kirest PH-540 (trade name) (EDTMP) manufactured by Kirest Co., Ltd.

The amount of the water-soluble resin contained in the water-soluble paint is preferably 0.1 to 1% by mass. By setting the addition amount of the water-soluble resin to 0.1% by mass or more, the adhesive strength between the SUS foil 12 and the sealant layer 13 can be increased. Further, by setting the addition amount of the water-soluble resin to 1% by mass or less, the adhesive strength between the SUS foil 12 and the sealant layer 13 can be increased.

The amount of the fluorometal compound contained in the water-soluble paint is preferably 0.1 to 2.5% by mass (preferably 0.8 to 2.5% by mass). By setting the addition amount of the metal fluoride compound to 0.1% by mass or more, the corrosion resistance of the SUS foil 12 to the electrolytic solution can be enhanced. Further, by setting the addition amount of the fluorometal compound to 2.5% by mass or less, it is possible to prevent precipitation from occurring in the water-soluble paint and suppress unevenness in the coating film.

When an organic chelating agent is used, the amount of the organic chelating agent contained in the water-soluble paint is preferably 0.1 to 1% by mass (preferably 0.3 to 1% by mass). By setting the addition amount of the fluorometal compound to 0.1% by mass or more, the compressive strength of the surface coating layers 17 and 18 can be increased, and cracking and peeling of the surface coating layers 17 and 18 can be suppressed. Further, by setting the addition amount of the organic chelating agent to 1% by mass or less, sufficient strength can be imparted to the surface coating layers 17 and 18.

The surface coating layers 17 and 18 can be formed by applying the water-soluble paint to the SUS foil 12 and performing heat drying, baking adhesion and cross-linking in an oven or the like.

In the battery exterior laminate 10 shown in FIG. 1, the surface coating layers 17 and 18 are formed on both sides of the SUS foil 12, but the surface coating layer is formed at least on the sealant layer 13 side of the SUS foil 12. It suffices if it has been done. That is, a configuration in which the surface coating layer 18 is omitted from the battery exterior laminate 10 of FIG. 1 (battery exterior laminate 60 shown in FIG. 5) is also possible.

The coating layer 16 (first coating layer) includes urethane resin, acrylic resin, polyvinylidene chloride, vinylidene chloride-vinyl chloride copolymer resin, maleic anhydride-modified polypropylene resin, polyester resin, epoxy resin, phenol resin, and phenoxy resin. Select from the resin group consisting of fluororesin, cellulose ester resin, cellulose ether resin, polyamide resin, polyphenylene ether resin (PPE), polyphenylene sulfide resin (PPS), polyaryl ether resin (PAE), and polyether ether ketone resin (PEEK). It is made of at least one kind of resin. For the coating layer 16, one of the resins constituting the resin group may be used alone, or two or more thereof may be used in combination. The coating layer 16 is preferably made of a material having excellent heat resistance.

The coating layer 16 is preferably the outermost layer of the battery exterior laminate 10. By forming the coating layer 16, the insulating property of the battery exterior laminate 10 can be enhanced, and the surface of the battery exterior laminate 10 can be prevented from being scratched. Further, even when the battery exterior laminate 10 comes into contact with the electrolytic solution, it is possible to prevent a change in appearance (discoloration or the like).

The coating layer 16 is preferably a thin film cured layer formed by applying and drying a solvent-based paint prepared by dissolving the resin in an organic solvent. Examples of the organic solvent include hydrocarbon solvents such as toluene, xylene, normal hexane, cyclohexane, methylcyclohexane, normal heptane, tridecane, and tetradecane; ethyl acetate, butyl acetate, methoxybutyl acetate, cellosolve acetate, amyl acetate, normal acetate. Ester solvents such as propyl and isopropyl acetate; ketone solvents such as acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone, DIBK (diisobutyl ketone), cyclohexanone, DAA (diacetone alcohol); methanol, ethanol, butanol, propanol, isopropyl Alcohol-based solvents such as alcohol and normal propyl alcohol; alcohol ether-based solvents such as methyl cell solve, ethyl cell solve, butyl cellosolve, dioxane, and ethylene glycol dimethyl ether, and the like can be mentioned. As the organic solvent, one of these may be used alone, or two or more thereof may be used in combination. Additives such as a desiccant and a stabilizer may be added to the solvent-based paint.

The solvent-based paint for forming the coating layer 16 can be applied by a known printing method such as an offset printing method, a gravure printing method, or a screen printing method.

The coating layer 16 can be colored by adding an achromatic or chromatic colorant to the solvent-based paint. The color of the coating layer 16 can be arbitrarily selected. The coating layer 16 may be uniformly colored over the entire region (or a partial region), or the plurality of regions may be colored different colors (or the same color from each other). The coating layer 16 can also be colored to display characters, figures, images, patterns and the like. These characters and the like may represent, for example, a product name, a manufacturer, and the like. By coloring the coating layer 16, the design of the battery exterior laminate 10 can be enhanced.

As the colorant, a pigment or a dye can be used. Pigments include, for example, quinacridone, anthraquinone, perylene, perinone, diketopyrrolopyrrole, isoindolinone, condensed azo, benzimidazolone, monoazo, insoluble azo, naphthol, and flavan. Organic pigments such as throne, anthrapyrimidine, quinophthalone, pyranthron, pyrazolone, thioindigo, anthanthrone, dioxazine, phthalocyanine, indanslon; metal complexes such as nickel dioxin yellow and copper azomethine yellow; Metal oxides such as titanium oxide, iron oxide and zinc oxide; metal salts such as barium sulfate and calcium carbonate; inorganic pigments such as carbon black, aluminum and mica can be mentioned. Examples of the dye include azo-based, quinoline-based, stilbene-based, thiazole-based, indigoid-based, anthraquinone-based, and oxazine-based dyes. The coating layer 16 may be colored by using a solvent-based paint containing ink. The ink is prepared by adding the colorant to, for example, a urethane-based or acrylic-based ink binder resin.

The thickness of the coating layer 16 can be, for example, 0.1 μm or more. It is more preferable that the coating layer 16 has a thickness of 2 μm or more. By setting the thickness of the coating layer 16 to 2 μm or more, it is possible to enhance the insulating property and enhance the effect of preventing the surface of the battery exterior laminate 10 from being scratched. Further, even when the battery exterior laminate 10 comes into contact with the electrolytic solution, it is possible to reliably prevent a change in appearance (discoloration or the like). The thickness of the coating layer 16 can be, for example, 20 μm or less. By setting the thickness of the coating layer 16 in the range of 2 to 20 μm, the overall thickness of the battery exterior laminate 10 can be suppressed.

The coefficient of static friction (based on JIS K7125) on the surface of the coating layer 16 is preferably 0.3 or less. By setting the coefficient of static friction within this range, it is possible to reduce damage and deformation of the battery exterior laminate 10 during drawing molding, and facilitate drawing molding.

The print layer 15 (second coating layer) can have the same structure as the coating layer 16. The print layer 15 is formed of a material exemplified as a material that can be used for the coating layer 16 (at least one resin selected from the resin group). The constituent material of the print layer 15 may be the same as the constituent material of the coating layer 16, or may be a material different from the constituent material of the coating layer 16. Like the coating layer 16, the printing layer 15 and the adhesive layer 14 are preferably thin film cured layers formed by applying and drying a solvent-based paint prepared by dissolving the resin in an organic solvent. The print layer 15 and the adhesive layer 14 can be colored by adding the colorant to the solvent-based paint, similarly to the coating layer 16. The color of the print layer 15 can be arbitrarily selected. The print layer 15 and the first adhesive layer 14 may be uniformly colored over the entire area (or a part of the area), or the plurality of areas are colored different colors (or the same color from each other). You may. The print layer 15 and the adhesive layer 14 can also be colored so as to display characters, figures, images, patterns, and the like. These characters and the like may represent, for example, a product name, a manufacturer, and the like. By coloring the print layer 15 and the adhesive layer 14, the design of the battery exterior laminate 10 can be enhanced. The preferred thickness of the print layer 15 is, for example, 0.1 μm to 10 μm. The print layer 15 is formed by a known printing method such as an offset printing method, a gravure printing method, or a screen printing method.

The battery exterior laminate 10 in the example of FIG. 1 has a print layer 15, but a configuration without the print layer 15 (battery exterior laminate 70 shown in FIG. 6) is also possible. Further, a configuration in which the surface coating layer 18 and the printing layer 15 are omitted from the battery exterior laminate 10 of FIG. 1 (battery exterior laminate 80 shown in FIG. 7) is also possible.

The sealant layer 13 is made of a polyolefin resin and is the innermost layer in the secondary battery 40 (see FIG. 2). The reason why the sealant layer 13 is the innermost layer is that the polyolefin resin has excellent resistance to the electrolytic solution of the lithium ion battery and has good heat sealability. Here, the heat sealability is the stability of the seal at a high temperature. The polyolefin resin constituting the sealant layer 13 preferably mainly contains either a polypropylene resin or a polyethylene resin.

The sealant layer 13 has a structure composed of a single layer or a multilayer laminated film. The surface of the sealant layer 13 on the interface side with the SUS foil 12 is a maleic anhydride-modified polyolefin resin (first polyolefin resin), an alloy material of a resin having an epoxy group and a polyolefin resin (second polyolefin resin), and It is preferably made of a heat-adhesive polyolefin resin containing at least one selected from the resin group consisting of an alloy material (third polyolefin resin) of a resin having an oxazoline group and a polyolefin resin. When the sealant layer 13 is a single layer, the sealant layer 13 is preferably made of the heat-adhesive polyolefin resin. When the sealant layer 13 has a multilayer structure, it is preferable that the sealant layer 13 has a layer made of the heat-adhesive polyolefin resin on the interface side with the SUS foil 12.

As the heat-adhesive polyolefin resin, one of the above-mentioned first to third polyolefin resins may be used alone, or two or more thereof may be mixed and used. Since the above-mentioned first to third polyolefin resins are firmly bonded to the water-soluble resin contained in the surface coating layer 17, the bonding strength between the sealant layer 13 and the surface coating layer 17 can be increased. When two or more of the above-mentioned first to third polyolefin resins are used, it is preferable to further knead these polyolefin resins to alloy them.

The maleic anhydride-modified polyolefin resin is obtained by modifying a part of the molecule of the polyolefin resin with maleic anhydride. Commercially available commercial products of maleic anhydride-modified polyolefin resin include Admer (acid-modified polyethylene, for example, SF600, SF700, NE060, acid-modified polypropylene, for example, QF551) manufactured by Mitsui Chemicals, Inc., Mitsubishi. Examples thereof include the trade name Modic (acid-modified polyethylene, for example, M545, acid-modified polypropylene, for example, P555) manufactured by Kagaku Co., Ltd.

As the resin having an epoxy group, a resin obtained by modifying a part of the molecule of the polyolefin resin into an epoxy group, or a resin obtained by melt-mixing an epoxy compound or a resin having an epoxy group with a polyolefin resin can be used. .. Examples of commercially available products suitable as epoxy compounds that can be used in the present invention include "Epicoat 1001" manufactured by Mitsubishi Chemical Corporation. Further, as the resin having an epoxy group, there is "Modiper-A4100" manufactured by NOF Corporation.

As the resin having an oxazoline group, a resin obtained by modifying a part of the molecule of the polyolefin resin into an oxazoline group and a resin obtained by melt-mixing the oxazoline compound with the polyolefin resin can be used. Examples of the oxazoline compound that can be used in the present invention include 2-isopropenyl-2-oxazoline. Examples of commercially available products suitable as oxazoline compounds include "Epocross WS-500" manufactured by Nippon Shokubai Co., Ltd.

The thickness of the sealant layer 13 is preferably 20 μm to 50 μm. By setting the thickness of the sealant layer 13 in this range, the pressure resistance of the heat-sealed portion can be increased and the infiltration of water into the battery exterior container 20 can be suppressed. Further, by setting the thickness of the sealant layer 13 in this range, it is possible to suppress the overall thickness of the battery exterior laminate 10 and reduce the thickness of the secondary battery 40.

When the sealant layer 13 has a multilayer structure, since it has the above-mentioned heat-adhesive polyolefin resin layer, it can be adhered to the SUS foil 12 by heat laminating. The adhesive strength between the sealant layer 13 and the SUS foil 12 is measured by the measuring method B (180 degree peeling) specified in JIS C6471, and is preferably 5N / 15 mm or more.

The overall thickness of the battery exterior laminate 10 can be, for example, 70 μm or less. This makes it possible to reduce the thickness of the secondary battery 40.

The battery exterior laminate 10 preferably has a tensile elongation at break of 40% or more in both the MD direction and the TD direction. When the tensile elongation at break is in this range, the corner portion is sufficiently stretched when the recess is formed by drawing forming, so that the fracture does not occur.
The tensile elongation at break is determined according to JIS K7127 when measured at a tensile speed of 50 mm / min.

Examples of the non-aqueous battery in which the battery exterior laminate is used include those using an organic electrolyte as an electrolytic solution, such as a lithium ion battery which is a secondary battery and an electric double layer capacitor. The organic electrolyte is generally one in which carbonic acid esters such as propylene carbonate (PC), diethyl carbonate (DEC), and ethylene carbonate are used as a medium, but the organic electrolyte is not particularly limited thereto.

Next, a method for manufacturing the secondary battery 40 shown in FIG. 2 will be described.
First, as shown in FIG. 3A, the battery exterior laminate 10 is formed into a tray shape having a recess 31 by drawing or the like to obtain a container body 30. The depth of the recess 31 can be, for example, 2 mm or more. A lithium ion battery (lithium ion battery 27 in FIG. 2) is housed in the recess 31 of the container body 30.
Next, as shown in FIG. 3B, the lid material 33 made of the battery exterior laminate 10 is superposed on the container body 30, and the flange portion 32 of the container body 30 and the peripheral edge portion 34 of the lid material 33 are heat-sealed. By doing so, the secondary battery 40 shown in FIG. 2 is obtained.

Since the coating layer 16 is formed in the battery exterior laminate 10 according to the present invention, the mechanical strength and slipperiness of the battery exterior laminate 10 can be increased. Since the coating layer 16 is formed by coating, it is firmly bonded to the SUS foil 12. In general, SUS foil is inferior in drawability to other metal foils such as aluminum foil, so it is difficult to set conditions for deep draw forming. In addition, peeling from adjacent layers is likely to occur.
On the other hand, in the battery exterior laminate 10 according to the present invention, the coating layer 16 is firmly bonded to the SUS foil 12, so that peeling can be prevented. Further, since the coating layer 16 enhances the mechanical strength and slipperiness, it is possible to reduce breakage (tear, etc.) and deformation of the battery exterior laminate 10 when the recess is formed by drawing molding. Therefore, even when deep drawing is performed, it is possible to prevent a decrease in the production efficiency of the secondary battery 40 due to a molding defect of the battery exterior container 20. Further, since the battery exterior laminate 10 is less likely to be damaged, it is possible to prevent deterioration of battery performance and ignition due to leakage of electrolytic solution and infiltration of water. Further, by forming the coating layer 16, it is possible to prevent the surface of the battery exterior laminate 10 from being damaged by an external force. Further, even when the battery exterior laminate 10 comes into contact with the electrolytic solution, it is possible to prevent a change in appearance (discoloration or the like). Since the coating layer 16 is formed by coating, the battery exterior laminate 10 can be formed thinner than when the resin film is laminated via an adhesive. Therefore, the battery outer container 20 can be made thinner.

In the battery exterior laminate 10 according to the present invention, the mechanical strength (tensile strength, etc.) can be increased by using the SUS foil 12, so that tears and pinholes may occur when the recesses are formed by drawing. Can be reduced. Further, since the SUS foil 12 having high mechanical strength is used, a structure (cover case or the like) for protecting the secondary battery 40 when transporting or mounting the secondary battery 40 becomes unnecessary or can be simplified. .. Therefore, it is possible to reduce the packing cost and reduce the size of the packing device. Further, since the SUS foil having high mechanical strength is used, the thickness of the battery exterior laminate can be reduced to increase the internal volume, and the volumetric efficiency of the battery can be improved. Further, since the SUS foil 12 on which the surface coating layer 17 is formed is used, deterioration due to corrosion is unlikely to occur even when the electrolytic solution is decomposed by the moisture infiltrated into the battery exterior container 20 to generate acid. Therefore, leakage of the electrolytic solution due to corrosion of the metal foil can be prevented, and deterioration of battery performance and ignition can be prevented.

In the battery exterior laminate 10, when the surface coating layer 17 is formed on the sealant layer 13 side of the SUS foil 12 and the sealant layer 13 has a multilayer structure, the heat-adhesive polyolefin resin layer is provided. The sealant layer 13 and the SUS foil 12 can be adhered very strongly. Therefore, when the concave portion is formed by drawing molding, the battery exterior laminate 10 can be prevented from being torn, and the sealant layer 13 and the SUS foil 12 can be prevented from peeling off. Therefore, it is possible to reduce the occurrence of defects during molding of the battery exterior container 20, improve the manufacturing yield of the secondary battery 40, and improve the production efficiency. Further, in the battery exterior laminate 10, by increasing the adhesive strength between the sealant layer 13 and the SUS foil 12, it is possible to prevent moisture from entering the inside of the battery exterior container 20 from the outside. Therefore, deterioration of the electrolytic solution over time can be suppressed, and the product life of the secondary battery 40 can be extended.

FIG. 4 shows the battery exterior laminate 50 which is the second embodiment of the battery exterior laminate of the present invention. In the battery exterior laminate 50, the base material layer 11 is formed between the coating layer 16 and the printing layer 15, and the adhesive layer 14 is formed between the printing layer 15 and the surface coating layer 18. This is different from the battery exterior laminate 10 shown in FIG.

The base material layer 11 is not particularly limited as long as it has sufficient mechanical strength, and is, for example, a polyester resin such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT); nylon ( Polyamide resin such as Ny); polyolefin resin such as stretched polypropylene (OPP); synthetic resin film made of polyetheretherketone (PEEK), polyphenylene sulfide (PPS) and the like can be used.

The base material layer 11 is preferably made of a single-layer or multi-layer film, which is a heat-resistant resin film having a melting point of 200 ° C. or higher. Examples of such a heat-resistant resin film include PET film, PEN film, PBT film, nylon film, PEEK film, PPS film and the like, and PET film which is advantageous in terms of cost is particularly preferable.

The adhesive layer 14 is not particularly limited as long as the base material layer 11 and the SUS foil 12 can be adhered to each other, but can be formed by, for example, a urethane-based adhesive or an epoxy-based adhesive. The adhesive layer 14 can be formed, for example, by dry laminating.

In the battery exterior laminate 50, since the base material layer 11 is formed of a heat-resistant resin film, the durability of the secondary battery 40 can be further improved.

The embodiments of the present invention have been described above with reference to the drawings. The present invention is not limited to these embodiments, and various modifications can be made without changing the gist of the present invention.

10, 50 ... Non-aqueous battery exterior laminate, 12 ... SUS foil, 13 ... Sealant layer, 14 ... Adhesive layer, 15 ... Printing layer, 16 ... Coating layer, 17, 18 ... Surface coating layer, 20 ... Non-aqueous battery Battery outer container, 27 ... lithium ion battery, 40 ... secondary battery.

Claims (2)

The SUS foil and the sealant layer are laminated,
A water-soluble paint containing a water-soluble resin, a metal fluoride compound, and an organic chelating agent or a (poly) phosphoric acid-based chelating agent was dried and cured on both sides of the SUS foil, and the thickness was 0.05 μm or more. A surface coating layer of 1.0 μm is formed.
The water-soluble resin is at least one selected from the group consisting of polyvinyl alcohol-based resins and polyvinyl ether-based resins.
The fluorometal compound has an action of cross-linking the water-soluble resin.
The organic chelating agent or the (poly) phosphoric acid-based chelating agent has an action of making the water-soluble resin water-resistant by chemically reacting with the water-soluble resin or the fluorometal compound.
A coating layer is laminated on the surface of the surface coating layer formed on the surface side of the SUS foil opposite to the sealant layer side, or a printing layer or printing is performed on the surface of the surface coating layer. The coating layer is laminated via a laminate of the layer and the base material layer.
The surface coating layer enhances the adhesive strength between the SUS foil and the sealant layer.
The coating layer is acrylic resin, polyvinylidene chloride, vinylidene chloride-vinyl chloride copolymer resin, maleic anhydride-modified polypropylene resin, polyester resin, epoxy resin, phenol resin, phenoxy resin, fluororesin, cellulose ester resin, cellulose ether resin. A coating layer formed of at least one resin selected from the resin group consisting of a polyamide resin, a polyvinylidene ether resin, a polyvinylidene sulfide resin, a polyaryl ether resin, and a polyether ether ketone resin.
The coating layer is a thin film cured layer formed by applying and drying a solvent-based paint (excluding those containing a curing accelerator) prepared by dissolving the resin in an organic solvent. A characteristic non-aqueous battery exterior laminate. The laminate for the exterior of a non-aqueous battery according to claim 1, wherein the fluorometal compound is a substance that crosslinks the water-soluble resin and passivates the surface of the SUS foil.

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