JP2017126565A - Lithium ion secondary battery exterior material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lithium ion secondary battery exterior material with a barrier layer, which can keep the characteristic of strength even when shaped in a thin film.SOLUTION: A lithium ion secondary battery exterior material comprises a base material layer, a barrier layer, and a heat seal layer which are stacked in turn. The barrier layer is a piece of stainless foil, of which the thickness is 10-60 μm. With a test piece of the lithium ion secondary battery exterior material of 15 mm in width, and 50 mm in length, the breaking strength is 100-700 MPa, and the rupture elongation is 3-30%.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a lithium ion secondary battery exterior material.

  In recent years, electronic devices such as personal computers and mobile phones have been downsized, and the lithium ion secondary batteries mounted on them have been similarly required to be downsized. For this reason, lithium ion secondary battery exterior materials (hereinafter sometimes simply referred to as exterior materials) are also shifting from cans to laminate films, and laminate films themselves are also becoming thinner.

  For example, there is a lithium ion secondary battery as shown in FIG. 4, and the structure is a tab lead in which the outer packaging material is an outer packaging material as shown in FIG. Is exposed to form an electrode terminal, and the outer periphery of the outer packaging material is heat-sealed.

  Examples of the laminate film type exterior material configuration include base material layer / barrier layer / corrosion prevention treatment layer / heat seal layer. In this exterior material, the base material layer is used as the outside air side, and the heat seal layer is used as the battery content side. In this configuration, for example, as disclosed in Patent Document 1, an aluminum foil is used as a barrier layer, and a chromate treatment layer is used as a corrosion prevention treatment layer. It functions to prevent corrosion.

  However, although the aluminum foil has good stretchability in response to the recent demand for reducing the thickness of the outer packaging material, there is a concern that the piercing strength required for the outer packaging material of the lithium ion secondary battery may be reduced if the aluminum foil is too thin due to low rigidity.

JP 2002-144479 A

  The present invention solves the above-described problems, and an object of the present invention is to provide a lithium-ion secondary battery exterior material provided with a barrier layer that can maintain strength characteristics even when it is thinned.

  In order to solve the above problems, a lithium ion secondary battery exterior material of the present invention is a lithium ion secondary battery exterior material in which a base material layer, a barrier layer, and a heat seal layer are sequentially laminated, and the barrier It is a stainless steel foil having a layer thickness of 10 μm or more and 60 μm or less, the breaking strength when the lithium ion secondary battery exterior material is a test piece having a width of 15 mm and a length of 50 mm is 100 MPa or more and 700 MPa or less, and the elongation at break Is 3% or more and 30% or less.

  In the lithium ion secondary battery exterior material of the present invention, phosphoric acid or phosphate is 100 parts by mass or more with respect to 100 parts by mass of the rare earth element-based oxide as a corrosion prevention treatment layer on at least one side of the barrier layer. It is preferable to have a layer (A) added in an amount of not more than part by mass.

  Further, in the lithium ion secondary battery exterior material of the present invention, the corrosion prevention treatment layer includes the layer (A) and a layer (B) having a cationic polymer and a crosslinking agent that crosslinks the cationic polymer (B). A structure is preferred.

The lithium ion secondary battery exterior material of the present invention has a mass a (g / m ² ) per unit area of the layer (A) and a mass b (g / m ² ) per unit area of the layer (B). Is preferably 2 ≧ b / a.

  The lithium ion secondary battery packaging material of the present invention is such that the cationic polymer is polyethyleneimine, an ionic polymer complex comprising a polymer having polyethyleneimine and carboxylic acid, and a primary amine grafted with a primary amine on an acrylic main skeleton. It is preferably at least one selected from the group consisting of a graft acrylic resin, polyallylamine or a derivative thereof, and aminophenol.

  The lithium ion secondary battery exterior material of the present invention is selected from the group consisting of a compound in which the crosslinking agent has any functional group of an isocyanate group, a glycidyl group, a carboxyl group, and an oxazoline group and a silane coupling agent. It is preferable that there is at least one.

  In the lithium ion secondary battery exterior material of the present invention, the layer (A) is preferably laminated in contact with the barrier layer.

Lithium-ion secondary battery exterior material of the present invention, it is preferable mass a per unit area of the layer (A) is not more than 0.010 g / ^{m 2} or more 0.200 g / ^{m 2.}

  In the lithium ion secondary battery exterior material of the present invention, the corrosion prevention treatment layer preferably has a multilayer structure further including a layer (C) containing an anionic polymer.

  In the lithium ion secondary battery exterior material of the present invention, the layer (C) containing the anionic polymer contains 1 to 100 parts by mass of a crosslinking agent that crosslinks the anionic polymer with respect to 100 parts by mass of the anionic polymer. A layer formed by addition is preferable.

The lithium ion secondary battery exterior material of the present invention has a mass a (g / m ² ) per unit area of the layer (A) and a mass b (g / m ² ) per unit area of the layer (B). And the mass c (g / m ² ) per unit area of the layer (C) is preferably 2 ≧ (b + c) / a.

  In the lithium ion secondary battery packaging material of the present invention, the rare earth element-based oxide is preferably cerium oxide.

  In the lithium ion secondary battery exterior material of the present invention, the phosphoric acid or phosphate is preferably condensed phosphoric acid or condensed phosphate.

  In the lithium ion secondary battery exterior material of the present invention, a first adhesive layer is provided between the base material layer and the barrier layer, and a second adhesive layer is provided between the barrier layer and the heat seal layer. It is preferable that

  In the lithium ion secondary battery exterior material of the present invention, the surface roughness Ra of the barrier layer is preferably 0.050 μm or more and 0.100 μm or less.

  According to the present invention, moldability can be maintained even if the barrier layer is thinned.

It is sectional drawing which shows an example of the layer structure of the lithium ion secondary battery exterior material of this invention. It is sectional drawing which shows another example of the layer structure of the lithium ion secondary battery exterior material of this invention. It is sectional drawing which shows another example of the layer structure of the lithium ion secondary battery exterior material of this invention. It is an overhead view which shows an example of a general lithium ion secondary battery. It is sectional drawing which shows an example of a general lithium ion secondary battery.

  Although the typical form for implementing this invention is described below, this invention is not limited to the following embodiment.

  Hereinafter, an example of an embodiment according to the present invention will be described in detail. FIG. 1 is a cross-sectional view showing a first embodiment of a lithium ion secondary battery exterior material of the present invention. 1 has a first adhesive layer 12, a corrosion prevention treatment layer 13, a barrier layer 14, a corrosion prevention treatment layer 13, a second adhesion layer 15, and a heat seal layer on one surface of a base material layer 11. 16 are sequentially laminated.

[Exterior material]
The packaging material 1 is used as a pouch for filling battery contents such as electrodes and electrolytes. The packaging material 1 is used with the base material layer 11 on the outside and the heat seal layer 16 on the electrolyte side. Since the exterior material 1 forms a recess for filling the battery contents by molding, it must withstand stretching and compression. Therefore, the exterior material 1 has a breaking strength of 100 MPa to 700 MPa and a breaking elongation of 3% when a tensile test (based on JIS C2151) is performed on a test piece sample having a width of 15 mm and a length of 50 mm using a tensile tester. It is preferable that it is 30% or less. If the packaging material 1 has a breaking strength of 100 MPa or more, the puncture strength required for a battery can be obtained even if the packaging material has a film thickness of 300 μm or less. However, if the packaging material 1 is higher than 700 MPa, slitting becomes difficult. If the breaking elongation of the exterior material 1 is 3% or more, the stretchability necessary for the molding process can be obtained, and it is technically difficult to make it higher than 30%.

  The thickness of the packaging material 1 is preferably 25 μm or more and 300 μm or less, and more preferably 30 μm or more and 150 μm or less. If the thickness of the outer packaging material 1 is 25 μm or more, barrier properties and mechanical characteristics required as a battery outer packaging material can be obtained. The insertion space of the battery is reduced, and the energy density of the battery is only lowered.

[Base material layer]
The base material layer 11 shown in FIG. 1 is provided for the purpose of imparting heat resistance in a heat sealing process at the time of manufacturing a lithium ion secondary battery, and for the purpose of countermeasures against pinholes that may occur during processing and distribution. It is preferable to use an insulating resin layer. Examples of such a resin layer include polyester resin, polyamide resin, polypropylene resin, polyurethane resin, polyimide resin, polyamideimide resin, polyether ether ketone resin, fluorine resin, polyvinyl alcohol resin, polyketone resin, polycarbonate resin, and the like. Can be mentioned. These resins can be used as a stretched or unstretched film, or can be used as a coating solution after being dissolved in a solvent. The base material layer may be a single layer or two or more layers. Among these resins, a stretched polyester film and a stretched polyamide film are preferable from the viewpoints of moldability, heat resistance, pinhole resistance, and insulation.

  The thickness of the base material layer 11 is preferably 3 μm or more and 40 μm or less, and more preferably 5 μm or more and 15 μm or less. When the thickness of the base material layer 11 is less than 3 μm, the pinhole resistance and the insulation are deteriorated, and when it is thicker than 40 μm, the moldability is deteriorated.

[First adhesive layer]
The 1st contact bonding layer 12 shown in FIG. 1 plays the role which affixes the base material layer 11 to the corrosion prevention process layer 13 or the barrier layer 14, when the base material layer 11 is a film. When the base material layer 11 is a coating liquid, the 1st contact bonding layer 12 does not need to be provided.

Examples of the material of the first adhesive layer 12 include a polyurethane-based adhesive having various polyols as a main component and an isocyanate compound or a derivative thereof as a curing agent component.
Examples of the polyol as the main component include polyester polyol, polyether polyol, polycarbonate polyol, acrylic polyol, and polyolefin polyol.

  Examples of polyester polyols include aliphatic dibasic acids such as succinic acid, glutaric acid, adipic acid, pimelic acid, speric acid, azelaic acid, sebacic acid, and brassic acid, and isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, etc. One or more aromatic dibasic acids and aliphatics such as ethylene glycol, propylene glycol, butanediol, neopentyl glycol, methylpentanediol, hexanediol, heptanediol, octanediol, nonanediol, decanediol, and dodecanediol And diols such as cycloaliphatic diols, cyclohexane diols, hydrogenated xylylene glycols, and other alicyclic diols, and aromatic diols such as xylylene glycols. It is also possible to use a polyurethane polyol in which the hydroxyl group contained in these polyols is chain-extended with an isocyanate compound.

  Diisocyanates such as tolylene diisocyanate, xylylene diisocyanate or a hydrogenated product thereof, hexamethylene diisocyanate, 4,4′-diphenylmethane diisocyanate or a hydrogenated product thereof, isophorone diisocyanate, etc. Or polyisocyanates such as adducts obtained by reacting these diisocyanates with polyhydric alcohols such as trimethylolpropane, burette obtained by reacting diisocyanates with water, and isocyanurate which is a trimer. Or blocked polyisocyanates obtained by blocking these polyisocyanates with alcohols, lactams, oximes and the like. These isocyanate compounds or derivatives thereof may be either organic solvent type or aqueous type.

  Usually, if it is a polyurethane-based adhesive used for dry lamination, the basic composition is sufficient in combination with the above main agent and curing agent, but other additives are added for the purpose of improving other adhesive properties and imparting various resistances. An agent may be included. Examples thereof include carbodiimide compounds, oxazoline compounds, epoxy compounds, phosphorus compounds, and silane coupling agents.

  The thickness of the first adhesive layer 12 is preferably 1 μm or more and 10 μm or less, and more preferably 3 μm or more and 7 μm or less.

(Corrosion prevention treatment layer)
1 includes a layer (A) 13a in which phosphoric acid or phosphate is added in an amount of 1 part by mass to 100 parts by mass with respect to 100 parts by mass of the rare earth element-based oxide, and a cationic polymer. And a layer (B) 13b having a crosslinking agent that crosslinks the cationic polymer and a layered structure in which an anionic polymer and a layer (C) 13c having a crosslinking agent that crosslinks the anionic polymer are laminated in this order. Further, as shown in FIG. 2, the corrosion prevention treatment layer 13 may be only the layer (A) 13a. Furthermore, as shown in FIG. 3, only the layer (A) 13a and the layer (B) 13b may be used. Further, the layer (B) 13b and the layer (C) 13c may be reversed (not shown).

  1 to 3, the corrosion prevention treatment layer 13 is provided on both surfaces of the barrier layer 14. However, the corrosion prevention treatment layer 13 may be provided on only one side.

(Rare earth element oxide)
Examples of rare earth element-based oxides include cerium oxide, yttrium oxide, neodymium oxide, and lanthanum oxide, with cerium oxide being particularly preferred.

  In the present invention, when the layer (A) 13a is formed, phosphoric acid or phosphate is used as a dispersion stabilizer, and a rare earth element oxide is dispersed and stabilized into a sol state (rare earth element). Based oxide sol). In such a case, a rare earth element-based oxide sol having an average particle diameter of 100 nm or less is particularly preferable. For the rare earth element-based oxide sol, various solvents such as water-based, alcohol-based, hydrocarbon-based, ketone-based, ester-based, and ether-based solvents can be used, and an aqueous rare-earth element-based oxide sol is particularly preferable.

  As the dispersion stabilizer, in addition to phosphoric acid or phosphate, inorganic acids such as nitric acid and hydrochloric acid, and organic acids such as acetic acid, malic acid, ascorbic acid and lactic acid may be used. Phosphate is particularly preferred as a dispersion stabilizer. Using phosphoric acid or phosphate as a dispersion stabilizer not only stabilizes the dispersion of rare earth oxides, but also improves adhesion to the metal foil, which is a barrier layer that utilizes the chelating ability of phosphoric acid. The addition of electrolytic solution resistance by capturing metal ions eluted under the influence of hydrofluoric acid (that is, formation of passive state), and the cohesion of layer (A) 13a is improved by the dehydration condensation of phosphoric acid even at low temperatures. Etc. can be expected. When the cohesive force is improved, the strength properties of the exterior material tend to be good.

  Examples of phosphoric acid compounds such as phosphoric acid or phosphate include orthophosphoric acid, pyrophosphoric acid, metaphosphoric acid, and alkali metal salts and ammonium salts thereof. In addition, various salts such as aluminum phosphate and titanium phosphate may be used. Further, condensed phosphoric acid such as trimetaphosphoric acid, tetrametaphosphoric acid, hexametaphosphoric acid and ultrametaphosphoric acid, or alkali metal salts and ammonium salts (condensed phosphates) thereof are preferable from the viewpoint of function expression.

  In particular, when the layer (A) 13a is formed using a sol-state rare earth element-based compound (that is, a rare earth element-based compound sol), considering the dry film-forming property (that is, the drying ability and the amount of heat), A dispersion stabilizer having excellent reactivity is preferred. Therefore, as the salt forming the phosphate, a Na ion salt having excellent dehydration condensation properties at low temperatures is preferable. Moreover, a water-soluble salt is preferable.

  The layer (A) 13a is formed by adding 1 part by mass or more and 100 parts by mass or less of phosphoric acid or phosphate to 100 parts by mass of the rare earth element-based oxide described above. 5 mass parts or more and 50 mass parts or less are preferable, and, as for the compounding quantity of phosphoric acid or a phosphate, 5 mass parts or more and 20 mass parts or less are more preferable. In the above, when the addition amount of phosphoric acid or phosphate is less than 1 part by mass, the stability of the obtained rare earth element-based oxide sol is lowered and the function as an exterior material becomes insufficient. On the other hand, when the addition amount exceeds 100 parts by mass, the function of the rare earth element-based oxide sol is deteriorated.

  As described above, even when using phosphate as a dispersion stabilizer, a salt that forms phosphate is preferably an Na ion salt, but when the amount of phosphate added exceeds the above range, Needless to say, the above-described adverse effects occur.

  Thus, by adding a phosphoric acid compound to the rare earth element-based oxide, not only the dispersion stabilization of the rare earth element-based oxide but also an inhibitory effect on the corrosion of the metal foil as the barrier layer can be imparted. Moreover, it becomes possible to improve the adhesiveness of the phosphoric acid compound to the metal foil, and a synergistic effect can be exhibited in terms of resistance to electrolyte.

  By the way, in normal chemical conversion treatment represented by chromate treatment, an inclined structure is formed between the barrier layer made of metal foil and the chemical conversion treatment layer. Therefore, the metal foil is treated with a chemical conversion treatment agent that contains hydrofluoric acid, hydrochloric acid, nitric acid, sulfuric acid, or a salt thereof, and a chemical conversion treatment layer is formed on the metal foil by reacting with chromium or a non-chromium compound. There are many cases. An example of the chemical conversion treatment is a phosphoric acid chromate treatment, which has the same basic principle whether it is an immersion type or a coating type using a resin binder. However, since these chemical conversion treatment agents use an acid, they are accompanied by corrosion of the work environment and coating equipment.

  In addition, regarding chromate treatment, a material using hexavalent chromium as a main component is designated as an environmentally hazardous substance, and is a material that has a good function but is environmentally undesirable. For this reason, trivalent chromium has been used. However, it is difficult to obtain the same function as hexavalent chromium, and the chromate treatment is not environmentally preferable as long as chromium is used.

  On the other hand, the corrosion prevention treatment layer used in the present invention as described above does not need to form an inclined structure with respect to the metal foil, and the definition is different from the chemical conversion treatment in that respect. Therefore, the properties of the anticorrosive treatment agent are not limited to acidity, neutrality, or alkalinity. Further, the corrosion prevention treatment layer does not give an environmentally harmful load.

Mass a per unit area of the layer of the corrosion prevention treatment layer 13 (A) 13a is preferably at 0.010 g / ^{m 2} or more 0.200 g / ^{m 2} or less, 0.040 g / ^{m 2} or more 0.100g / M ² or less is more preferable. When the mass a is smaller than 0.010 g / m ² , the absolute amount of the rare earth element-based oxide and phosphoric acid or phosphate having the effect of preventing the corrosion of the barrier layer which is a metal foil is reduced, so It becomes difficult to obtain hydrofluoric acid resistance. On the other hand, when the mass a is larger than 0.200 g / m ² , the sol-gel reaction accompanying the drying of the rare earth element-based oxide sol used in the present invention is difficult to proceed (that is, the amount of heat becomes insufficient, and the sol-gel reaction The agglomeration force of the rare earth element-based oxide sol is reduced, and the layer may not be formed.

  Therefore, if the mass a per unit area of the layer (A) 13a is within the above range, the electrolyte solution resistance can be maintained, and the cohesive strength of the rare earth element-based oxide sol can be maintained. Enough strength can be imparted.

(Cationic polymer)
As a result of intensive studies using various compounds in order to further improve the electrolytic solution resistance and hydrofluoric acid resistance required for the exterior material, the present inventors have determined that the cationic polymer is resistant to electrolytic solution and hydrofluoric acid. It was found to be an excellent compound. This is presumably because trapping fluorine ions with a cationic group (anion catcher) suppresses damage to the barrier layer, which is a metal foil.

  Examples of the cationic polymer include an amine-containing polymer, polyethyleneimine, an ionic polymer complex composed of a polymer having polyethyleneimine and a carboxylic acid, and a primary amine graft obtained by grafting a primary amine to an acrylic main skeleton. Acrylic resin, polyallylamine or a derivative thereof, and aminophenol are preferable. Particularly preferred is polyallylamine or a derivative thereof.

  As a polymer having a carboxylic acid that forms an ionic polymer complex with polyethyleneimine, a polycarboxylic acid (salt) such as polyacrylic acid or an ionic salt thereof, a copolymer having a comonomer introduced therein, carboxymethylcellulose, The polysaccharide which has carboxyl groups, such as the ionic salt, is mentioned.

  As the polyallylamine, homopolymers or copolymers such as allylamine, allylamine amide sulfate, diallylamine, and dimethylallylamine can be used. These amines may be free amines or amines stabilized with acetic acid or hydrochloric acid. Moreover, it is also possible to use maleic acid, sulfur dioxide, etc. as a copolymer component. Furthermore, it is also possible to use a type in which a primary amine is partially methoxylated to give thermal crosslinkability.

  In addition, in the case of aminophenol, it is possible to use a type in which thermal crosslinkability is imparted by partially methoxylating a primary amine.

  These cationic polymers may be used alone or in combination of two or more.

  Thus, the cationic polymer is an effective material for the exterior material, and in the corrosion prevention treatment layer 13, by using the layer (B) having the cationic polymer in combination with the layer (A) described above, We can expect improvement of function.

  By the way, in consideration of performing water immersion in the water resistance evaluation of the exterior material, the corrosion prevention treatment layer 13 is required to have water resistance and water resistance adhesion as an anchor coating agent. A cationic polymer having a cationic group such as amine is effective in terms of resistance to hydrofluoric acid, but since it is water-based, the use of a cationic polymer alone results in poor water resistance.

  Therefore, as a result of intensive studies on the problem of delamination associated with water immersion after the evaluation of the electrolyte, the present inventors have found that the cationic polymer is inferior in water resistance. We focused on the problem of water resistance at the interface. Furthermore, as a solution to the factors, the former may be to add a cross-linking agent, and the latter may be to form an interaction at the adhesive interface, but one of the latter factors is to improve the former. It was found that the latter could be solved. These findings have led to the solution of water resistance. That is, the following crosslinking agent was used.

(Crosslinking agent for crosslinking cationic polymer)
The crosslinking agent for making the cationic polymer into a crosslinked structure is at least one selected from the group consisting of a compound having any functional group of isocyanate group, glycidyl group, carboxyl group and oxazoline group and a silane coupling agent. Is mentioned.

  Examples of the compound having an isocyanate group include tolylene diisocyanate, xylylene diisocyanate or a hydrogenated product thereof, hexamethylene diisocyanate, 4,4′-diphenylmethane diisocyanate or a hydrogenated product thereof, diisocyanates such as isophorone diisocyanate, or these isocyanates. Polyisocyanates such as adducts obtained by reacting polyhydric alcohols such as trimethylolpropane, burettes obtained by reacting isocyanates with water, isocyanurates which are trimers, or the like Examples thereof include blocked polyisocyanates obtained by blocking polyisocyanates with alcohols, lactams, oximes and the like.

  Examples of the compound having a glycidyl group include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, 1,4-butanediol, 1,6-hexanediol, Epoxy compounds that react with glycols such as neopentyl glycol and epichlorohydrin, epoxy compounds that react with polychlorinated alcohols such as glycerin, polyglycerin, trimethylolpropane, pentaerythritol, sorbitol and epichlorohydrin, phthalic acid, terephthalic acid, Examples thereof include an epoxy compound in which a dicarboxylic acid such as oxalic acid or adipic acid and epichlorohydrin are allowed to act.

  Examples of the compound having a carboxyl group include various fatty acids or aromatic dicarboxylic acids. Furthermore, poly (meth) acrylic acid or alkali (earth) metal salts of poly (meth) acrylic acid may be used. .

  As the compound having an oxazoline group, a low molecular compound having two or more oxazoline units can be used. In addition, when using a polymerizable monomer such as isopropenyl oxazoline, it is copolymerized with an acrylic monomer such as (meth) acrylic acid, (meth) acrylic acid alkyl ester, (meth) acrylic acid hydroxyalkyl, etc. Can be used.

  Furthermore, it is preferable to use a silane coupling agent capable of selectively reacting an amine and a functional group to form a siloxane bond at the crosslinking point as the crosslinking agent. Examples of silane coupling agents include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, and γ-chloropropylmethoxysilane. Vinyltrichlorosilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β (aminoethyl) -γ-aminopropyltrimethoxysilane, and γ-isocyanatopropyltriethoxysilane. In particular, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-aminopropyltriethoxysilane, and γ-isocyanatopropyltriethoxysilane are considered in consideration of reactivity with a cationic polymer or a copolymer thereof. Is preferred.

  These crosslinking agents are preferably added in an amount of 1 to 50 parts by mass with respect to 100 parts by mass of the cationic polymer. When the addition amount of the crosslinking agent is less than 1 part by mass, the crosslinked structure becomes insufficient. On the other hand, when there is more addition amount than 50 mass parts, there exists a possibility that the pot life of a coating liquid may fall.

  In addition, when the cationic polymer is a polyallylamine derivative obtained by methoxycarbonylating a primary amine of polyallylamine, since it has thermal crosslinkability, it is assumed that a crosslinking agent is added without adding a crosslinking agent. It can be regarded as substantially equivalent. Moreover, as a method of crosslinking the cationic polymer, besides using the above-mentioned crosslinking agent, a method of forming a crosslinked structure such as ionic crosslinking using titanium or a zirconium compound as a crosslinking agent may be used.

  A crosslinking agent may be used individually by 1 type, and may use 2 or more types together. Moreover, you may use together a crosslinking agent and a silane coupling agent.

  As described above, the cationic polymer is a very effective material in terms of trapping hydrofluoric acid. Moreover, water resistance can also be improved by adding a crosslinking agent. Therefore, as shown in FIG. 3, the corrosion prevention treatment layer 13 includes a layer (B) 13b having a cationic polymer, whereby the resistance to electrolytic solution, the resistance to hydrofluoric acid, and the water resistance are further improved.

  However, the layer (B) 13b having the cationic polymer as described above does not have a function of protecting the metal foil from corrosion. Therefore, as shown in FIG. 3, the corrosion prevention treatment layer 13 has a multilayer structure including the layer (A) 13a together with the layer (B) 13b, whereby the corrosion prevention effect of the metal foil can be obtained.

  As will be described in detail later, the layer (A) 13a is preferably laminated directly on the barrier layer 14 as shown in FIG. The layer (A) 13a is formed of a sol state (rare earth element oxide sol) in which the rare earth element oxide is dispersed and stabilized with phosphoric acid or phosphate as described above. A) 13a substantially has a structure in which sol particles of rare earth element-based oxides are densely packed.

On the other hand, the layer (B) 13b is laminated on the layer (A) 13a while filling the gap of the layer (A) 13a where the sol particles are densely packed. That is, the corrosion prevention treatment composition (B) constituting the layer (B) 13b is coated on the layer (A) 13a while penetrating into the gaps of the layer (A) 13a to form the layer (B) 13b. . At this time, the corrosion prevention treatment composition that has penetrated into the gaps of the layer (A) 13a is thermally cross-linked, so that the layer (B) 13b expresses the protective layer effect of the layer (A) 13a.

In order for the layer (B) 13b to more effectively express the protective layer role of the layer (A) 13a, the mass a (g / m ² ) per unit area of the layer (A) and the layer (B ) With respect to the mass b (g / m ² ) per unit area only needs to satisfy 2 ≧ b / a.

  Even when the mass relationship (b / a) of each layer exceeds 2, it is possible for the layer (B) 13b to serve as a protective layer for the layer (A) 13a. In addition to the ratio of filling the gap of 13a, the ratio of the layer (B) 13b stacked on the layer (A) 13a increases more than necessary. The cationic polymer in the layer (B) 13b is combined with the rare earth element-based oxide, phosphoric acid or phosphate in the layer (A) 13a in the layer (B) 13b, rather than being present alone. However, it tends to express the resistance to electrolytic solution and hydrofluoric acid more effectively. Therefore, when the mass relationship (b / a) of each layer exceeds 2, as a result, it exists alone without being complexed with the rare earth element-based oxide, phosphoric acid or phosphate in the layer (A) 13a. Since the proportion of the cationic polymer is increased, the electrolytic solution resistance and hydrofluoric acid resistance functions may not be sufficiently exhibited, and the electrolytic solution resistance and hydrofluoric acid resistance may be reduced.

  Moreover, since the coating amount of a corrosion prevention treatment composition (B) increases, it may become difficult to harden | cure. In order to sufficiently cure the corrosion prevention treatment composition (B), the drying temperature may be set high or the curing time may be set long. As a result, the productivity may be lowered. Therefore, from the viewpoint of improving the electrolytic solution resistance and hydrofluoric acid resistance while maintaining the productivity, the mass relationship (b / a) of each layer is preferably 2 ≧ b / a, and 1.5 ≧ b /A≧0.01 is more preferable, and 1.0 ≧ b / a ≧ 0.1 is particularly preferable.

  In addition, although the said relationship is based on the mass of a layer, if the specific gravity of each layer can be calculated | required, it can also convert into the thickness of the corrosion prevention process layer 13. FIG.

(Anionic polymer)
As a result of further studies, the present inventors have also found that an anionic polymer is a compound that improves the stability of the layer (A). The effect of an anionic polymer is to protect the hard and brittle layer (A) with an acrylic resin component or to remove phosphate-derived ion contamination (especially Na ion contamination) contained in a rare earth element-based oxide sol. The effect of trapping (cation catcher) is mentioned.

  Generally, it is not limited to the use of a lithium ion secondary battery exterior material, for example, in a protective layer provided for the purpose of preventing corrosion of a metal foil by a corrosive compound, ion contamination, particularly alkali metal ions such as Na ions, If alkaline earth metal ions are contained, there is a problem that the protective layer is attacked starting from this ion contamination. Therefore, the use of an anionic polymer for the purpose of immobilizing ion contamination such as Na ions contained in the rare earth element-based oxide sol is effective in improving the resistance of the exterior material.

  The anionic polymer is a material having characteristics opposite to those of the cationic polymer described above. Specific examples include a polymer having a carboxyl group, and poly (meth) acrylic acid or a salt thereof, or a copolymer having (meth) acrylic acid or a salt thereof as a main component.

  The components used as the copolymer include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, t-butyl group, 2-ethylhexyl group, cyclohexyl group and the like. Alkyl (meth) acrylate monomers having an alkyl group, (meth) acrylamide, N-alkyl (meth) acrylamide and N, N-dialkyl (meth) acrylamide (alkyl groups include methyl, ethyl and n-propyl groups) , I-propyl group, n-butyl group, i-butyl group, t-butyl group, 2-ethylhexyl group, cyclohexyl group, etc.), N-alkoxy (meth) acrylamide and N, N-dialkoxy (meth) acrylamide ( Alkoxy groups include methoxy, ethoxy, butoxy, isobutoxy, etc.), N-methyl Amide group-containing monomers such as diol (meth) acrylamide and N-phenyl (meth) acrylamide, hydroxyl-containing monomers such as 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate, glycidyl (meth) acrylate, Glycidyl group-containing monomers such as allyl glycidyl ether, silane-containing monomers such as (meth) acryloxypropyltrimethoxysilane, (meth) acryloxypropyltriethoxysilane, and isocyanate group-containing monomers such as (meth) acryloxypropyl isocyanate Polymerized ones can be mentioned.

  The anionic polymer is a material that is very effective in trapping ion contamination. As shown in FIG. 1, the layer (C) 13c containing the anionic polymer is replaced with the above-described layers (A) 13a and ( B) By using in combination with 13b, further improvement of the function can be expected. However, as in the case of the cationic polymer, the anionic polymer is water-based, and if used alone, results in poor water resistance. Therefore, it is preferable to add a crosslinking agent for crosslinking the anionic polymer to the layer (C) 13c.

(Crosslinking agent for crosslinking anionic polymer)
As the cross-linking agent, one type may be used alone, or two or more types may be used in combination, from the above-mentioned cross-linking agents that cross-link the cationic polymer. Moreover, you may use together a crosslinking agent and a silane coupling agent.

  The crosslinking agent is preferably added in an amount of 1 part by mass or more and 100 parts by mass or less, and more preferably 1 part by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the anionic polymer. When the addition amount of the crosslinking agent is less than 1 part by mass, the crosslinked structure becomes insufficient. On the other hand, when there is more addition amount than 100 mass parts, there exists a possibility that a coating liquid pot life may fall.

As described above, the anionic polymer is a material that is very effective in capturing ion contamination, and the water resistance can be improved by adding a crosslinking agent. However, the layer (C) 13c having an anionic polymer as described above does not have a function of protecting the metal foil from corrosion.
Therefore, as shown in FIG. 1, the corrosion prevention treatment layer 13 has a multilayer structure including not only the layer (C) 13c but also the layer (A) 13a, whereby the corrosion prevention effect of the metal foil can be obtained. .

  The anionic polymer in the layer (C) 13c is more complex with the rare earth element-based oxide, phosphoric acid or phosphate in the layer (A) 13a than when it exists alone. There is a tendency that the function of acidity and hydrofluoric acid is expressed more effectively. Therefore, when the ratio of the layer (C) 13c laminated on the layer (A) 13a is increased more than necessary, the resultant is combined with the rare earth element-based oxide, phosphoric acid or phosphate in the layer (A) 13a. Without increasing the proportion of anionic polymer present alone. As a result, the electrolytic solution resistance and hydrofluoric acid resistance functions may not be sufficiently exhibited, and the electrolytic solution resistance and hydrofluoric acid resistance may be reduced.

In order to more effectively express the resistance to electrolytic solution and hydrofluoric acid, the mass a (g / m ² ) per unit area of the layer (A) and the mass b per unit area of the layer (B) ( g / m ² ) and the mass c (g / m ² ) per unit area of the layer (C) should satisfy 2 ≧ (b + c) / a.

  Even when the relationship (b + c) / a of the mass of each layer exceeds the above range, the effects of the present invention may be exhibited. In this case, the corrosion prevention treatment composition (B) or the corrosion prevention treatment composition (C ), The amount of coating increases, which may make it difficult to cure.

  In order to sufficiently cure the corrosion prevention treatment composition (B) and the corrosion prevention treatment composition (C), the drying temperature may be set higher or the curing time may be set longer. May be reduced.

  Accordingly, from the viewpoint of improving the electrolytic solution resistance and hydrofluoric acid resistance while maintaining productivity, the mass relationship (b + c) / a of each layer is preferably 2 ≧ (b + c) / a, and 1.5 ≧ (b + c ) /A≧0.01 is more preferable, and 1.0 ≧ (b + c) /a≧0.1 is particularly preferable.

  In the present invention, the thickness of the corrosion prevention treatment layer 13 shown in FIG. 1 is not particularly limited, but is preferably 0.01 μm or more and 10 μm or less, for example.

[Barrier layer]
The barrier layer 14 serves to prevent moisture from entering the lithium ion secondary battery. Various metal foils having high moisture barrier properties can be used as the barrier layer 14, but stainless steel foil is preferable from the viewpoint of thinning. Since stainless steel contains 50% or more of iron, it has greater strength, hardness, toughness, etc. than other metal materials, and can provide the mechanical strength required when manufacturing and using batteries.

  However, in general, a material having a high strength is difficult to stretch. For this reason, when a barrier layer having a strength that is too high is used for the exterior material, the tensile elongation necessary for the molding process is insufficient, and cracks and pinholes may occur in the exterior material during the molding process. For the reasons described above, the balance between strength and elongation is important for the barrier layer of the battery exterior material, and the present inventors have found that the stainless steel foil maintains the balance.

  Stainless steel has high corrosion resistance because it contains chromium. Since the oxidation of chromium is more rapid than the oxidation of iron, a thin transparent film of chromium oxide is formed on the surface of the alloy, which protects the alloy from atmospheric moisture, oxygen, and harmful gases. However, since there is a concern that the alloy becomes brittle when the chromium content is too large, the chromium content is 10.5% or more in order to achieve both the effect of improving the corrosion resistance by chromium and the prevention of embrittlement of the alloy. It is preferable that it is 30% or less.

  Stainless steel is broadly classified into precipitation hardening, martensite, ferrite, and austenite, and any of them may be used, but austenite that is soft and has good workability is preferable.

  Various surface treatments may be applied to the stainless steel foil. Examples of the surface treatment include various plating treatments such as copper plating, nickel plating, chromium plating, zinc plating, tin plating, lead plating, gold plating, silver plating, rhodium plating, platinum plating, palladium plating, and ruthenium plating. It is done. Above all, various strikes such as nickel strike plating with strong hydrochloric acid acidic bath, silver strike plating with high plating bath concentration and high current, and copper strike plating, which are known to be effective in improving the adhesion of metal materials. Plating is preferred.

  As the barrier layer 14, the surface roughness Ra measured by using a 50 × objective lens with a laser microscope (LEXT OLS4100, manufactured by OLYMPUS) is preferably 0.050 μm or more and 0.100 μm or less, and 0.060 μm. More preferably, it is 0.090 μm or less. If the surface roughness of the barrier layer 14 is within the above range, the corrosion prevention treatment layer adheres firmly to the barrier layer 14, and the corrosion prevention function is fully exhibited. If the surface roughness of the barrier layer 14 is less than the lower limit value, the wettability of the corrosion prevention treatment liquid is poor. If the surface roughness is larger than the upper limit value, it cannot be applied to the entire surface unless the corrosion prevention treatment layer is thick. It will end up.

  The film thickness of the barrier layer 14 is preferably 10 μm or more and 60 μm or less, and more preferably 20 μm or more and 30 μm or less. If the thickness of the barrier layer 14 is less than 10 μm, the processability of the exterior material is inferior and the manufacture as a foil becomes difficult. On the other hand, if it is thicker than 60 μm, the exterior material itself becomes heavy and the workability is not improved, leading to a decrease in volume energy density.

  If the film thickness of the barrier layer 14 is 20 μm or more and 30 μm or less, a barrier layer having a sufficiently high barrier property and good workability when processed as an exterior material can be obtained.

[Second adhesive layer]
The second adhesive layer 15 is provided for attaching the heat seal layer 16 on the barrier layer 14 provided with the corrosion prevention treatment layer 13. The second adhesive layer 15 is manufactured by techniques such as extrusion lamination, thermal lamination, and dry lamination. The second adhesive layer 15 is preferably the following (i) or (ii).
(I) Acid-modified polyolefin resin (α)
(Ii) An acid-modified polyolefin resin (α) (30% by mass or more and 99% by mass or less) is mixed with an isocyanate compound or a derivative thereof (β) and a silane coupling agent (γ) so that (β) + (γ) is 1. The resin composition mix | blended by the mass% or more and 70 mass% or less. However, when the mass ratio of the isocyanate compound or its derivative (β) and the silane coupling agent (γ) is (β) + (γ) = 100, (β) :( γ) = 10 or more and 90 or less: 90 or less 10 That's it. Note that (α) + {(β) + (γ)} = 100 mass%.

  When the second adhesive layer 15 is (ii) above, the acid-modified polyolefin resin (α) is inferior in electrolytic solution resistance when it is more than 99% by mass, and when it is less than 30% by mass, it adheres to the heat seal layer 16 described later Inferior to sex. Preferably, 60% by mass or more and 80% by mass or less of the acid-modified polyolefin resin (α) is blended.

  On the other hand, when the mass ratio of the isocyanate compound or its derivative (β) and the silane coupling agent (γ) is out of the above range, the electrolytic solution resistance is deteriorated. More preferably, (β) :( γ) = 50 or more and 80 or less: 50 or less and 20 or more.

  The acid-modified polyolefin resin (α) is preferably an acid-modified polyolefin resin obtained by graft-modifying maleic anhydride or the like to a polyolefin resin. Examples of the polyolefin resin include low density, medium density, high density polyethylene, ethylene-α olefin copolymer, homo, block, or random polypropylene, propylene-α olefin copolymer.

  These polyolefin resin may be used individually by 1 type, and may use 2 or more types together. In addition, a dispersion type in which the above-described resin is dispersed in an organic solvent may be used, whereby an additive effective for various adhesions, an isocyanate compound or a derivative thereof (β) and a silane coupling agent (γ) described later are used. Can be blended.

  Diisocyanates such as tolylene diisocyanate, xylylene diisocyanate or a hydrogenated product thereof, hexamethylene diisocyanate, 4,4′-diphenylmethane diisocyanate or a hydrogenated product thereof, isophorone diisocyanate, or the like as the isocyanate compound or derivative thereof (β) An adduct obtained by reacting a diisocyanate with a polyhydric alcohol such as trimethylolpropane, a burette obtained by reacting a diisocyanate with water, a polyisocyanate such as an isocyanurate which is a trimer, or Examples include blocked polyisocyanates obtained by blocking these polyisocyanates with alcohols, lactams, oximes and the like.

  These isocyanate compounds or derivatives thereof (β) may be either organic solvent type or aqueous type.

  Silane coupling agents (γ) include vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-glycol. Sidoxypropyltriethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-chloropropylmethoxysilane, vinyltrichlorosilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N -Β (aminoethyl) -γ-aminopropyltrimethoxysilane, γ-isocyanatopropyltriethoxysilane, and the like.

  In particular, the silane coupling agent (γ) preferably has a functional group reactive with the acid-modified polyolefin resin (α). From such a viewpoint, as the silane coupling agent (γ), epoxy silane and amino silane are preferable, and isocyanate silane is also preferable although the reactivity is low.

  The thickness of the second adhesive layer 15 is preferably 1 μm or more and 40 μm or less, and more preferably 3 μm or more and 20 μm or less.

[Heat seal layer]
The heat seal layer 16 is a layer for sealing after packing the battery contents in the exterior material 1. Examples of the component constituting the heat seal layer 16 include a polyolefin resin or an acid-modified polyolefin resin obtained by graft-modifying maleic anhydride or the like on a polyolefin resin. As polyolefin resin, you may select and use 1 or more types from various polyolefin resin illustrated previously in description of the 2nd contact bonding layer 15. FIG.

  The heat seal layer 16 may be a single layer film or a multilayer film in which a plurality of layers are laminated. Depending on the required function, for example, a multilayer film in which a resin such as an ethylene-cycloolefin copolymer or polymethylpentene is interposed may be used in terms of imparting moisture resistance.

  Furthermore, you may mix | blend various additives, for example, a flame retardant, a slip agent, an antiblocking agent, antioxidant, a light stabilizer, a tackifier, etc. with the heat seal layer 16.

  The thickness of the heat seal layer 16 is preferably 10 μm or more and 100 μm or less, and more preferably 20 μm or more and 50 μm or less.

[Method of manufacturing exterior material]
Next, although the manufacturing method of the lithium ion secondary battery exterior material 1 of this invention shown in FIG. 1 is demonstrated, it is not limited to this.

(Lamination process of corrosion prevention treatment layer on barrier layer)
Corrosion prevention treatment composition (A) containing rare earth element-based oxide and phosphoric acid or phosphate of 1 part by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the rare earth element-based oxide, barrier layer 14 It is coated on top, dried, cured and baked to form the layer (A) 13a. Next, a corrosion prevention treatment composition (B) containing a cationic polymer and a crosslinking agent that crosslinks the cationic polymer is applied onto the layer (A) 13a, followed by drying, curing, and baking, and then the layer (B) 13b is formed. Next, the anti-corrosion treatment composition (C) containing an anionic polymer and a crosslinking agent for crosslinking the anionic polymer is applied onto the layer (B) 13b, dried, cured and baked, and then the layer (C) 13c To form. In this way, the corrosion prevention treatment layer 13 composed of the layer (A) 13a, the layer (B) 13b, and the layer (C) 13c is laminated on both surfaces of the barrier layer.

  In the corrosion prevention treatment layer 13, the layer (A) 13 a is preferably directly laminated on the barrier layer 14 (the layer (A) is laminated in contact with the barrier layer), but the layer (B ) The order of 13b and layer (C) 13c is not particularly limited. Further, the layer (A) 13a, the layer (B) 13b, and the layer (C) 13c may be repeatedly laminated as necessary.

  As a coating method, a known method is used, and examples thereof include a gravure coater, a gravure reverse coater, a roll coater, a reverse roll coater, a die coater, a bar coater, a kiss coater, and a comma coater.

(Lamination process of base material layer)
The base material layer 11 is bonded onto the barrier layer 14 on which the corrosion prevention treatment layer 13 is laminated. As a method of bonding, dry lamination, non-solvent lamination, wet lamination, or the like is used, and both are bonded with the above-described adhesive, and the base layer 11 / first adhesive layer 12 / corrosion prevention treatment layer 13 / A laminate composed of the barrier layer 14 / corrosion prevention treatment layer 13 is produced.

  In addition, when the base material layer 11 is not a film, a coating liquid is applied by the same method as the coating of the corrosion prevention treatment layer 13 described above, or a molten resin is extruded, etc. to prevent corrosion. The base material layer 11 can be provided on the barrier layer 14 on which the treatment layer 13 is laminated.

(Lamination process of heat seal layer)
Examples of the method for laminating the heat seal layer 16 on the laminate include a dry process and a wet process.

  In the case of a dry process, an adhesive resin is extruded and laminated on the corrosion prevention treatment layer 13 inside the barrier layer of the laminate, and a heat seal layer 16 obtained by an inflation method or a cast method is further laminated, Material 1 is manufactured. The corrosion prevention treatment layer 13 may be provided in-line during this extrusion lamination. Thereafter, for the purpose of improving the adhesion between the corrosion prevention treatment composition and the adhesive resin, heat treatment (aging treatment, thermal lamination, etc.) can be applied. In the present invention, the layer structure as described above is used. By forming, the exterior material 1 having excellent adhesion can be obtained even with a small amount of heat during extrusion lamination.

  It is also possible to produce a multilayer film with the adhesive resin and the heat seal layer 16 by an inflation method or a casting method, and to laminate the multilayer film on the laminate by thermal lamination.

  In the case of the wet process, the dispersion of the acid-modified polyolefin resin (α) is applied on the corrosion prevention treatment layer 13 inside the barrier layer of the laminate, and the acid-modified polyolefin resin (α) is coated. The solvent is removed at a temperature equal to or higher than the melting point, and the resin is melted and softened for baking. Thereafter, the exterior material 1 is manufactured by laminating the heat seal layer 16 by a heat treatment such as thermal lamination.

  As a coating method, the various coating methods illustrated by description of the lamination process of the corrosion prevention process layer 13 to the barrier layer 14 are mentioned.

  The lithium ion secondary battery outer packaging material of the present invention produced as described above has a base material layer 11 / first adhesive layer 12 / corrosion prevention treatment layer 13 / barrier layer 14 / corrosion prevention treatment layer 13 / second adhesion. A laminate composed of layer 15 / heat seal layer 16 is formed. Moreover, in the lithium ion secondary battery exterior material of the present invention, the corrosion prevention treatment layer includes a layer (A) having a rare earth element-based oxide or the like, or a layer (A) and a layer (B) having a cationic polymer or the like. By including the multilayer structure, the electrolytic solution resistance, hydrofluoric acid resistance, and water resistance are excellent. If the layer (C) having an anionic polymer is further included, the electrolytic solution resistance, hydrofluoric acid resistance, and water resistance will be better.

  Although the Example of this invention is shown below, this invention is not limited to this.

[Materials used]
(Base material layer)
A-1: Biaxially stretched polyamide film (25 μm).
A-2: Polyamic acid resin (25 μm).

(First adhesive layer)
B-1: Polyester urethane adhesive (5 μm).

(Corrosion prevention treatment layer)
Raw material CA-1 of layer (A) having rare earth element-based oxide: “Sodium polyphosphate stabilized cerium oxide sol” using distilled water as a solvent and adjusted to a solid content concentration of 10 wt%. In addition, 10 mass parts of Na salt of phosphoric acid was mix | blended with respect to 100 mass parts of cerium oxides, and cerium oxide sol was obtained.
CA-2: “Sodium polyphosphate stabilized cerium oxide sol” adjusted to a solid concentration of 10 wt% using distilled water as a solvent. In addition, 0.5 mass part of sodium salt of phosphoric acid was mix | blended with respect to 100 mass parts of cerium oxides, and cerium oxide sol was obtained.
CA-3: “Sodium polyphosphate-stabilized cerium oxide sol” adjusted to a solid concentration of 10 wt% using distilled water as a solvent. In addition, 110 mass parts of phosphoric acid Na salt was mix | blended with respect to 100 mass parts of cerium oxide, and cerium oxide sol was obtained.
-Raw material CB-1 of layer (B) having cationic polymer: 90 wt% of "polyallylamine" adjusted to 5 wt% with distilled water as solvent and "epichlorohydrin addition of 1,6-hexanediol" Composition "consisting of 10 wt%.
CB-2: A composition comprising 90% by weight of “polyethyleneimine” and 10% by weight of “acrylic-isopropenyloxazoline copolymer” adjusted to a solid content concentration of 5% by weight using distilled water as a solvent.
CB-3: A composition obtained by adding 5 parts by mass of “aminopropyltrimethoxysilane” to 100 parts by mass of the CB-2 composition.
CB-4: “Polyallylamine” in which distilled water was used as a solvent and the solid concentration was adjusted to 5 wt%.
CB-5: “Polyethyleneimine” using distilled water as a solvent and having a solid content concentration adjusted to 5 wt%.
-Raw material CC-1 of layer (C) having an anionic polymer or the like: 90 wt% of "polyacrylic acid ammonium salt" using distilled water as a solvent and adjusting the solid content concentration to 5 wt%, and "acrylic-isopropenyloxazoline" A composition comprising 10% by weight of a copolymer.
CC-2: “Ammonium polyacrylate” in which distilled water was used as a solvent and the solid concentration was adjusted to 5 wt%.

(Barrier layer)
D-1: SUS304 foil (20 μm) having a surface roughness of 0.076 μm.
D-2: Soft aluminum foil 8079 material (20 μm) having a surface roughness of 0.054 μm.
D-3: SUS631 foil (20 μm) having a surface roughness of 0.086 μm.
D-4: SUS304 foil (8 μm) having a surface roughness of 0.069 μm.
D-5: SUS304 foil (70 μm) having a surface roughness of 0.081 μm.

(Second adhesive layer)
E-1: Polypropylene resin (20 μm) graft-modified with maleic anhydride.

(Heat seal layer)
F-1: An unstretched polypropylene film (40 μm) whose corona treatment was applied to the second adhesive layer side.

[Method for manufacturing exterior material]
First, compositions (CA-1 to CA-3, CB-1 to CB-5, CC-1 to CC-2) constituting each corrosion prevention treatment layer on both surfaces of the barrier layers (D-1 to D-5). ) Is suitably applied by microgravure coating, and is baked at 150 ° C. or more and 250 ° C. or less in a drying unit according to the components of each corrosion prevention treatment layer, and layers 1 to 3 are formed on the barrier layer. A corrosion prevention treatment layer provided in order (ie, layer 1 is on the barrier layer side) was laminated. In Table 1, the mass per unit area (mg / m ² ) in the column of the corrosion prevention treatment layer is the coating amount of the raw material of each layer.

  Next, the adhesive composition (B-1) was applied onto the barrier layer provided with the corrosion prevention treatment layer by using a dry lamination technique, and the base material layer (A-1) was bonded. Moreover, the base material layer (A-2) was formed by directly coating on the barrier layer provided with the corrosion prevention treatment layer.

  Finally, after the adhesive composition (E-1) was extruded by an extrusion apparatus onto the corrosion prevention treatment layer inside the barrier layer of the laminate, an adhesive layer was formed, and then the heat seal layer (F-1 ) A heat seal layer was formed by laminating and laminating films.

  Through the above steps, exterior materials of the examples and comparative examples having the configuration shown in Table 1 were produced.

[Method for evaluating exterior materials]
(Break strength test)
The sample was cut into a dumbbell shape having a width of 15 mm and a length of 50 mm, and the breaking strength was measured with a tensile tester (manufactured by Shimadzu Corporation). The tensile speed was 50 mm / min.

(Break elongation test)
A sample similar to the strength test was measured for tensile elongation using a tensile tester (manufactured by Shimadzu Corporation). The tensile speed was 50 mm / min. The breaking strength test and breaking elongation test were performed in accordance with JISC2151.

(Electrolytic solution resistance)
An electrolyte solution prepared by adjusting the LiPF ₆ to 1.5 M in a solution of ethylene carbonate / diethyl carbonate / dimethyl carbonate = 1/1/1 was prepared and filled into a container having an internal volume of 250 ml. A sample cut to a size of 100 mm × 15 mm was placed therein, and after sealing, it was stored for 3 hours in an environment of 85 degrees. The peeled state of the sample after storage was evaluated according to the following criteria.
◯: Delamination is not achieved, the laminate strength is 100 gf / 15 mm or more (crosshead speed is 300 mm / min), or the heat seal layer is broken.
X: The float by delamination can be confirmed (impossible).

(Anhydrous acid resistance)
The same operation as in the electrolytic solution resistance evaluation was performed except that the electrolytic solution used in the electrolytic solution resistance evaluation was mixed with water at 1500 ppm to be used as the electrolytic solution. Thereafter, the sample was immersed in water all day and night, and the peeled state of the sample was confirmed. The evaluation criteria are the same as in the electrolytic solution resistance evaluation.

(water resistant)
A sample cut to a size of 100 mm × 15 mm was made in advance so as to be easily peeled off, and immersed in water for a whole day and night in that state to confirm the peeled state. The evaluation criteria are the same as in the evaluation of resistance to electrolytic solution.

(Puncture resistance)
A nail having a diameter of 4 mm and a length of 100 mm was pressed against a sample cut into a size of 50 mm × 50 mm, and the load when the sample was pierced was measured.
○: Load is 30N or more ×: Load is less than 30N

(Moldability)
A sample cut to a size of 100 mm × 200 mm was subjected to a molding process with a depth of 2 mm using a drawing apparatus.
○: The sample could be drawn without abnormality.
X: The sample was broken.

[Examples 1 to 4]
Using the materials shown in Table 1 below, lithium ion secondary battery exterior materials of Examples 1 to 4 were produced. Various evaluations were performed on the prepared samples. The results are shown in Table 2.

[Comparative Examples 1-4, Reference Examples 5-14]
Lithium ion secondary battery exterior materials of Comparative Examples 1 to 4 and Reference Examples 5 to 14 were produced using the materials shown in Table 1 below. Various evaluations were performed on the prepared samples. The evaluation results are shown in Table 2 below.

  As shown in Table 1, in Examples 1 to 4, Reference Examples 6 and 9 to 14, good results were obtained in puncture resistance and moldability, and the problems of the present invention were solved. In Examples 1 to 4, good results were obtained in all evaluations. On the other hand, in Comparative Examples 1 to 4, good results were not obtained. In Reference Example 7, since the coating amount of the raw material of the corrosion prevention treatment layer (A) is too large, the cohesive strength of the rare earth element-based oxide sol is reduced and a coating film cannot be formed. Reference Example 8 is a corrosion prevention treatment. Since the amount of Na phosphate contained in the raw material of the layer (A) was too small, the stability of the oxide sol was lowered and a coating film could not be formed.

  In Comparative Examples 1 to 4, mechanical properties such as puncture resistance and moldability were insufficient by changing the material of the barrier layer or the film thickness.

  Reference Example 5 has no corrosion prevention treatment layer, Reference Example 6 has too little coating amount of the raw material of the corrosion prevention treatment layer (A), and Reference Example 9 is phosphorus contained in the raw material of the corrosion prevention treatment layer (A). Since there was too much quantity of acid Na salt, the favorable result was not shown from the viewpoint of electrolytic solution resistance or hydrofluoric acid resistance, respectively. Reference Example 10 and Reference Example 11 did not contain a cationic polymer crosslinking agent in the raw material of the layer (B), and did not show good results from the viewpoint of water resistance. In Reference Example 12, the coating amount of the raw material of layer (A) is small and the coating amount of the raw material of layer (B) is large, and in Reference Example 13, the raw material of layer (A) and the raw material of layer (B) are interchanged. Reference Example 14 did not contain an anionic polymer crosslinking agent in the raw material of the layer (C), and did not show good results in terms of resistance to electrolyte and hydrofluoric acid, respectively.

  From the above, in a lithium ion battery exterior material comprising a base material layer, a barrier layer, and a heat seal layer, a stainless steel foil having a thickness of 10 μm to 60 μm is used as the barrier layer, the breaking strength is 100 MPa to 700 MPa, and the elongation at break is It was found that by using an exterior material having a degree of 3% or more and 30% or less, sufficient mechanical properties as a battery exterior material can be obtained.

1: Lithium ion secondary battery exterior material 11: base material layer 12: first adhesive layer 13: corrosion prevention treatment layer 13a: layer (A)
13b: Layer (B)
13c: Layer (C)
14: Barrier layer 15: Second adhesive layer 16: Heat seal layer

Claims (15)

A lithium ion secondary battery exterior material in which a base material layer, a barrier layer, and a heat seal layer are sequentially laminated,
The barrier layer is a stainless steel foil having a thickness of 10 μm or more and 60 μm or less,
The breaking strength (based on JIS C2151) when the lithium ion secondary battery exterior material is a test piece having a width of 15 mm and a length of 50 mm is 100 MPa or more and 700 MPa or less, and the elongation at break is 3% or more and 30% or less. A lithium ion secondary battery exterior material characterized by the above.   At least one surface of the barrier layer has a layer (A) in which phosphoric acid or phosphate is added to 1 part by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the rare earth element-based oxide as a corrosion prevention treatment layer. The lithium ion secondary battery exterior material according to claim 1, wherein   3. The corrosion prevention treatment layer has a multilayer structure including at least the layer (A) and a layer (B) having a cationic polymer and a crosslinking agent that crosslinks the cationic polymer. The lithium ion secondary battery exterior material described in 1. The relationship between the mass a (g / m ² ) per unit area of the layer (A) and the mass b (g / m ² ) per unit area of the layer (B) is 2 ≧ b / a. The lithium ion secondary battery exterior material according to claim 3, wherein   The cationic polymer is polyethyleneimine, an ionic polymer complex comprising a polymer having polyethyleneimine and a carboxylic acid, a primary amine-grafted acrylic resin in which a primary amine is grafted to an acrylic main skeleton, polyallylamine or a derivative thereof, and amino The lithium ion secondary battery outer packaging material according to claim 3 or 4, wherein the outer packaging material is at least one selected from the group consisting of phenol.   The cross-linking agent is at least one selected from the group consisting of a compound having a functional group of any one of an isocyanate group, a glycidyl group, a carboxyl group, and an oxazoline group and a silane coupling agent. Item 6. The lithium ion secondary battery exterior material according to any one of Items 3 to 5.   The lithium ion secondary battery exterior material according to any one of claims 3 to 6, wherein the layer (A) is laminated in contact with the barrier layer. Wherein the mass a per unit area of the layer (A) is not more than 0.010 g / ^{m 2} or more 0.200 g / ^{m 2,} lithium ions according to any one of claims 3-7 Secondary battery exterior material.   The lithium ion secondary battery exterior material according to any one of claims 3 to 8, wherein the corrosion prevention treatment layer further has a multilayer structure including a layer (C) containing an anionic polymer.   The layer (C) containing the anionic polymer is a layer formed by adding 1 part by mass or more and 100 parts by mass or less of a crosslinking agent that crosslinks the anionic polymer to 100 parts by mass of the anionic polymer. The lithium ion secondary battery exterior material according to claim 9. The mass a (g / m ² ) per unit area of the layer (A), the mass b (g / m ² ) per unit area of the layer (B), and the unit area per unit area of the layer (C) 11. The lithium ion secondary battery exterior material according to claim 9, wherein the relationship with the mass c (g / m ² ) is 2 ≧ (b + c) / a.   The lithium ion secondary battery exterior material according to any one of claims 2 to 11, wherein the rare earth element-based oxide is cerium oxide.   The lithium ion secondary battery exterior material according to any one of claims 2 to 12, wherein the phosphoric acid or phosphate is condensed phosphoric acid or condensed phosphate.   The first adhesive layer is provided between the base material layer and the barrier layer, and the second adhesive layer is provided between the barrier layer and the heat seal layer. 14. The lithium ion secondary battery exterior material according to any one of 13 above.   The surface roughness Ra of the said barrier layer is 0.050 micrometer or more and 0.100 micrometer or less, The lithium ion secondary battery exterior material of any one of Claims 1-14 characterized by the above-mentioned.