JP5310922B1 - Packaging materials for electrochemical cells - Google Patents

Abstract

Disclosed is a packaging material for an electrochemical cell that prevents the occurrence of a short circuit.
A base material layer made of at least a resin film, a heat adhesive layer made of a thermoadhesive resin and disposed in the innermost layer, and a barrier made of a metal foil disposed between the base material layer and the heat adhesive layer. And a plurality of metal oxide fine particles 111 having an average particle size of 0.7 μm or less deposited on the surface of the barrier layer 114 on the heat bonding layer side. An insulating layer 117 is formed.
[Selection] Figure 3

Description

  The present invention relates to a packaging material for an electrochemical cell that forms a packaging body for an electrochemical cell.

  A conventional packaging material for a lithium ion battery is disclosed in Patent Document 1. This packaging material is a laminate in which a base material layer, a barrier layer made of metal foil, and an innermost thermal adhesive layer are sequentially laminated, and by heat-sealing the peripheral thermal adhesive part with the thermal adhesive layers facing each other. A package of electrochemical cells is formed. The package is provided with a space for accommodating the electrochemical cell body, and the electrode tabs connected to the positive electrode current collector and the negative electrode current collector of the electrochemical cell body extend to the outside while being sandwiched by the package at the thermal bonding portion. ing.

  Lithium ion batteries include those having liquid, gel-like, and polymer-like electrolytes, and the positive electrode / negative electrode active material is made of a polymer. The positive electrode active material and the negative electrode active material are coated on the positive electrode current collector and the negative electrode current collector, respectively. In addition, aluminum, nickel, or the like is used for the positive electrode current collector, and copper, nickel, stainless steel, or the like is used for the negative electrode current collector. Polymer positive electrode materials such as metal oxide, carbon black, metal sulfide, electrolytic solution, polyacrylonitrile and the like are used as the positive electrode active substance. As the negative electrode active material, a polymer negative electrode material such as lithium metal, alloy, carbon, electrolyte, polyacrylonitrile or the like is used.

JP 2007-273398 A

  However, according to the packaging material described above, the electrode active material is peeled off and scattered in the battery manufacturing process, or minute metallic foreign matters such as electrode tab fragments are mixed and the electrodes are disposed on the surface of the thermal adhesive layer disposed on the inner surface of the packaging material. When the active material or metal foreign matter adheres, the thermal adhesive layer melts due to heat and pressure at the time of heat sealing and becomes thin, and the electrode active material or minute metallic foreign matter bites into the thermal adhesive layer at the sandwiched portion of the electrode tab, There has been a problem that a short circuit occurs between the electrode tab and the barrier layer. In addition, when the electrode tab has burrs, there is a problem that the thermal adhesive layer is broken to reach the barrier layer to cause a short circuit.

  An object of this invention is to provide the packaging material for electrochemical cells which prevents generation | occurrence | production of a short circuit in view of the said problem.

In order to achieve the above object, the present invention provides a base material layer made of a resin film, a heat adhesive layer made of a heat-adhesive resin disposed in the innermost layer, and the base material layer and the heat adhesive layer. A packaging material for an electrochemical cell comprising at least a barrier layer made of a metal foil and a plurality of metal oxide fine particles on the surface of the barrier layer on the side of the thermal adhesive layer. An insulating layer formed by being deposited over the layer is provided, the metal oxide fine particles have an average particle size of 0.7 μm or less, and the thickness of the insulating layer is X (μm), and the metal oxide fine particles A packaging material for electrochemical cells, wherein the following formula (1) is satisfied when the average particle diameter of Y is μ (μm).

  According to this configuration, the metal oxide fine particles are excellent in heat resistance and strong, and are a highly insulating material, so that they are not easily melted or crushed by heat and pressure during heat sealing. Thereby, the insulating layer formed by depositing metal oxide fine particles in three or more layers is also excellent in heat resistance and insulation. Therefore, even when there are burrs on the electrode tab or when electrode active material or metallic foreign matter adheres to the inner surface of the thermal adhesive layer and burrs, electrode active material or minute metallic foreign matter bite into the thermal adhesive layer during heat sealing, These foreign substances are obstructed by the insulating layer on which the metal oxide fine particles are deposited and do not easily reach the metal foil of the barrier layer, thereby preventing a decrease in insulating properties.

  According to the present invention, in the packaging material for an electrochemical cell having the above structure, the insulating layer is formed by applying a treatment liquid in which the metal oxide fine particles are dispersed in a binder solution.

  The present invention is also characterized in that the binder solution contains phosphoric acid in the electrochemical cell packaging material having the above-described configuration. According to this configuration, the adhesion of the insulating layer to the adjacent resin is improved.

  The present invention is also characterized in that, in the packaging material for an electrochemical cell having the above structure, the insulating layer has a thickness of 2 μm or less.

  Further, the present invention is characterized in that, in the packaging material for an electrochemical cell having the above-described configuration, the surface of the insulating layer on the heat bonding layer side is subjected to a chromium-based chemical conversion treatment or a non-chromium-based chemical conversion treatment. According to this configuration, the corrosion resistance and adhesion of the insulating layer are further improved.

According to the present invention, the metal oxide fine particles are excellent in heat resistance and strong, and are a highly insulating material, so that they are not easily melted or crushed by heat and pressure during heat sealing. Therefore, when there are burrs on the electrode tab or electrode active material or metallic foreign matter scattered or mixed on the inner surface of the thermal adhesive layer adheres, the burrs, electrode active material or minute metallic foreign matter bite into the thermal adhesive layer during heat sealing. Even in such a case, these foreign substances are blocked by the insulating layer on which the metal oxide fine particles are deposited, so that it is difficult to reach the metal foil of the barrier layer, and the deterioration of the insulating property is prevented. Thereby, it is possible to prevent a short circuit from occurring between the electrode tab and the barrier layer. Further, metal oxide fine particles having an average particle size of 0.7 μm or less are deposited to form an insulating layer, the thickness of the insulating layer is X (μm), and the average particle size of the metal oxide fine particles is Y (μm). When satisfying the following formula (1), the gap formed between the adjacent metal oxide fine particles can be reduced to increase the volume occupation ratio of the metal oxide fine particles contained in the insulating layer. . Thereby, the insulation of an insulating layer can be improved more.

The perspective view of the lithium ion battery using the packaging material for electrochemical cells which concerns on 1st Embodiment of this invention. Schematic sectional view showing the layer structure of the packaging material for electrochemical cells according to the first embodiment of the present invention The schematic sectional drawing which expands and shows the insulating layer of the packaging material for electrochemical cells which concerns on 1st Embodiment of this invention The schematic sectional drawing which shows the layer structure of the packaging material for electrochemical cells which concerns on 2nd Embodiment of this invention

<First Embodiment>
Hereinafter, the packaging material 110 for an electrochemical cell according to the first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of a lithium ion battery 121 using a packaging material 110 for electrochemical cells according to the first embodiment (hereinafter may be referred to as “packaging material”), and FIG. 2 relates to the first embodiment. 3 is a schematic cross-sectional view showing a layer structure of a packaging material 110 for an electrochemical cell that is a packaging body of a lithium ion battery 121. FIG.

  The lithium ion battery 121 is configured by housing a lithium ion battery main body 122 containing an electrolytic solution in the package 120. The package 120 includes a storage portion 120a that stores the lithium ion battery main body 122 and a sheet-like lid portion 120b that covers the storage portion 120a.

  The package 120 has a thermal bonding portion 120c at the periphery where the storage portion 120a and the lid portion 120b overlap each other, and the inside is sealed. At this time, the positive electrode tab 123a and the negative electrode tab 123b connected to the lithium ion battery main body 122 extend to the outside while being sandwiched by the storage portion 120a and the lid portion 120b with a tab film (not shown) interposed in the thermal bonding portion 120. ing.

  The lithium ion battery main body 122 includes a positive electrode, a negative electrode, and a cell (all not shown). The positive electrode includes a positive electrode active material and a positive electrode current collector, and the negative electrode includes a negative electrode active material and a negative electrode current collector. The cell is configured by alternately stacking a plurality of positive electrode plates and negative electrode plates with separators interposed therebetween, and includes an electrolytic solution filled between the positive electrode and the negative electrode. At this time, the positive electrode current collector extends from each positive electrode plate, and the negative electrode current collector extends from each negative electrode plate. The plurality of extended positive electrode current collectors and negative electrode current collectors are superposed and stacked, and are connected to one positive electrode tab 123a and one negative electrode tab 123b.

  As shown in FIG. 2, the packaging material 110 is configured by sequentially laminating a base material layer 112, a barrier layer 114, and a heat bonding layer 116. The base material layer 112 and the barrier layer 114 are bonded via an adhesive layer 113, and the barrier layer 114 and the thermal adhesive layer 116 are bonded via an acid-modified polyolefin layer 115. In addition, an insulating layer 117 is provided on the thermal adhesive layer 116 side of the barrier layer 114.

  The base material layer 112 is made of a resin film and imparts high puncture resistance (pinhole resistance), insulation, workability, and the like to the package 120. Moreover, it is necessary to have the extensibility which can endure the press at the time of emboss molding.

  As the base material layer 112, a resin film such as stretched polyester or stretched polyamide can be arbitrarily selected and used. Examples of the polyester include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, copolymerized polyester, and polycarbonate. Examples of the polyamide include nylon 6, nylon 6,6, a copolymer of nylon 6 and nylon 6,6, nylon 6,10, polymetaxylylene adipamide (MXD6), and the like.

  The barrier layer 114 is made of a metal foil, and prevents water vapor, oxygen, light, and the like from entering the lithium ion battery 121 from the outside. Specific examples of the metal foil that forms the barrier layer 114 include aluminum, stainless steel, and titanium. Among these, aluminum is preferably used.

  Further, the aluminum is preferably soft aluminum, particularly preferably annealed aluminum. These aluminums can further prevent the generation of wrinkles and pinholes that occur during the production of the packaging material 110 for electrochemical cells. Moreover, 10-200 micrometers is preferable and, as for the thickness of metal foil, 20-100 micrometers is especially preferable. This thickness stabilizes the pinhole and processing suitability (pouching, embossing formability) of the barrier layer 114 alone and improves pinhole resistance.

  FIG. 3 is a cross-sectional view schematically showing the insulating layer 117. As shown in FIG. 3, the insulating layer 117 has a predetermined thickness, and is formed by depositing metal oxide fine particles 111 in three or more layers. Since the metal oxide fine particles 111 are excellent in heat resistance and strong and are a highly insulating material, they are not easily melted or crushed by heat and pressure during heat sealing. Accordingly, when there is a burr on the positive electrode tab 123a and the negative electrode tab 123b, or when an electrode active material or a minute metal foreign matter scattered or mixed on the inner surface of the thermal adhesive layer 116, the burr, electrode active material or metal at the time of heat sealing is used. When foreign matter bites into the thermal bonding layer 116, these foreign matter is blocked by the insulating layer 117 on which the metal oxide fine particles 111 are deposited, and it is difficult for the foreign matter to reach the metal foil of the barrier layer 114, thereby preventing a decrease in insulation. Is done. Thereby, it can prevent that a short circuit generate | occur | produces via the lithium ion battery main body 122 containing the electrolyte solution inside the package 120 between the positive electrode tab 123a, the negative electrode tab 123b, and the barrier layer 114.

  The metal oxide fine particles 111 are preferably particles having an average particle diameter of 0.01 μm or more and 0.7 μm or less. Thereby, the gap formed between the adjacent metal oxide fine particles 111 is reduced, and the volume occupation ratio of the metal oxide fine particles 111 contained in the insulating layer 117 can be increased. Therefore, the insulating property of the insulating layer 117 can be further improved.

  Note that by using the spherical metal oxide fine particles 111, the metal oxide fine particles 111 are easily deposited on the upper surface of the barrier layer 114. However, non-spherical fine particles such as a plate shape and a needle shape may be contained in addition to the spherical shape.

  Moreover, it is preferable that the thickness of an insulating layer is 2 micrometers or less. When the thickness of the insulating layer 117 is 2 μm or less, sufficient moldability can be obtained. In addition, when the thickness of the insulating layer 117 is larger than 2 μm, the packaging material 110 becomes hard and pinholes are easily generated during molding.

Further, when the thickness of the insulating layer 117 is X (μm) and the average particle diameter of the metal oxide fine particles 111 is Y (μm), the insulating property of the insulating layer 117 is satisfied by satisfying the following formula (1). Can be further improved.

  In addition, the average particle diameter Y (micrometer) as used in the field of this invention is an average value of the diameter (sphere conversion particle diameter) when converting the metal oxide fine particle 111 into the sphere of the same volume. The average particle diameter of the metal oxide fine particles 111 can be measured using a laser diffraction / scattering particle size distribution measuring apparatus. In addition, in the case of including a particle size of 0.01 μm or less, 200 or more metal oxide fine particles 111 arbitrarily extracted from a photograph taken with a transmission electron microscope are arbitrarily extracted, the respective particle sizes are measured, and the average value is obtained. Can be calculated.

  The thickness X (μm) of the insulating layer 117 in the present invention is a distance from the upper surface of the barrier layer 114 to the upper surface of the insulating layer 117, and the upper surface of the insulating layer 117 is uneven due to the outer shape of the metal oxide fine particles 111. Is formed, the height from the upper surface of the insulating layer 117 to the upper end of the metal fine particles 111 partially protruding.

  In addition, when X / Y of Formula (1) is 2.5 or less, the thickness of the insulating layer 117 is thin with respect to the average particle diameter of the metal oxide fine particles 111, and sufficient insulation cannot be obtained. Moreover, if the average particle diameter Y of the metal oxide fine particles 111 is 0.7 μm or less, the upper limit value of X / Y is not particularly limited.

  The insulating layer 117 is formed by applying a treatment liquid in which a binder solution is added to an aqueous solution in which the metal oxide fine particles 111 are dispersed. Thereby, since a continuous process is possible and a water washing process is unnecessary, processing cost can be made cheap.

  Further, since the binder solution contains phosphoric acid, phosphoric acid chemically melts part of the metal oxide fine particles 111 and part of the barrier layer 114. Thus, the insulating layer 117 adheres to the adjacent barrier layer 114 when moisture is evaporated by drying.

  Examples of the metal oxide fine particles 111 include aluminum oxide, cerium oxide, titanium oxide, tin oxide, and zirconium oxide.

  Note that the insulating layer 117 is formed by applying a treatment liquid in which the metal oxide fine particles 111 are dispersed in a binder solution to the surface of the barrier layer 114 and then drying it. The treatment liquid is generated by adding a binder solution to an aqueous solution in which the metal oxide fine particles 111 are dispersed. Examples of the binder solution include phosphoric acid, condensed phosphoric acid, aluminum phosphate, epoxy resin, or a mixed solution thereof.

  By using these binder solutions, the adhesion of the insulating layer 117 to the adjacent resin is improved. Thereby, delamination between the insulating layer 117 and the acid-modified polyolefin layer 115 can be prevented. Further, by using these binder solutions, the insulating layer 117 imparts corrosion resistance to the surface of the barrier layer 114 formed of aluminum. Therefore, the insulating layer 117 can prevent the aluminum surface from being corroded by hydrogen fluoride generated by the reaction between the electrolytic solution and moisture.

  The insulating layer 117 may be formed by selecting a known coating method such as a bar coating method, a roll coating method, a gravure coating method, or a dipping method from a treatment liquid in which metal oxide fine particles are dispersed in a binder solution. By applying and forming the insulating layer 117, it is possible to reduce the processing cost because continuous processing is possible and the water washing step is unnecessary.

  In addition, before forming the insulating layer 117, it is desirable that the surface of the barrier layer 114 is previously treated by a known degreasing method such as an alkali dipping method, an electrolytic cleaning method, an acid cleaning method, or an acid activation method. Thereby, the adhesiveness (wetting property) of the surface of the barrier layer 114 is improved, and the plurality of metal oxide fine particles 111 can be uniformly deposited to form the insulating layer 117 with a uniform thickness.

  The thermal adhesive layer 116 is disposed on the innermost layer of the packaging material 110 and is made of a thermal adhesive resin that melts by heat and fuses the opposing packaging materials 110 to each other. The resin type differs depending on whether or not a tab film is interposed between the thermal adhesive layer 116 and the positive electrode tab 123a or the negative electrode tab 123b. When a tab film is interposed, a film made of a simple substance or a mixture of olefinic resins may be used. In the case where no tab film is interposed, an acid-modified olefin graft-modified with an unsaturated carboxylic acid may be used.

  Also, polypropylene is preferably used as the thermal bonding layer 116. In addition, a film composed of a single layer or a multilayer of linear low density polyethylene and medium density polyethylene can also be used. Moreover, the film which consists of a single layer or a multilayer which consists of a mixed resin of linear low density polyethylene and medium density polyethylene can also be used.

  Further, when each type of polypropylene is used for the thermal bonding layer 116, for example, each type such as random propylene, homopropylene, block propylene and the like can be used. Further, a low crystalline ethylene-butene copolymer, a low crystalline propylene-butene copolymer, or a terpolymer may be added to the linear low density polyethylene or medium density polyethylene. The turbopolymer is composed of a three-component copolymer of ethylene, butene, and propylene. Moreover, you may add antiblocking agents (AB agent), such as a silica, a zeolite, and an acrylic resin bead, and a fatty acid amide type slip agent to these resin.

  The acid-modified polyolefin layer 115 is a resin layer that stably bonds the barrier layer 114 and the thermal adhesive layer 116, and acid-modified polypropylene is preferably used. In addition, the acid-modified polyolefin layer 115 needs to be appropriately selected and used depending on the resin type used for the thermal bonding layer 116. For this reason, when using an acid-modified polyolefin other than acid-modified polypropylene, a polyolefin graft-modified with an unsaturated carboxylic acid, a copolymer of ethylene and acrylic acid graft-modified with an unsaturated carboxylic acid, or a graft modification with an unsaturated carboxylic acid Copolymer of propylene and acrylic acid, copolymer of ethylene and methacrylic acid graft-modified with unsaturated carboxylic acid, copolymer of propylene and methacrylic acid graft-modified with unsaturated carboxylic acid, unsaturated carboxylic acid A metal-crosslinked polyolefin or the like graft-modified with an acid can be used. Further, 5% or more of a butene component, an ethylene-propylene-butene copolymer, an amorphous ethylene-propylene copolymer, a propylene-α-olefin copolymer, etc. may be added to these resins as necessary. Good.

When using acid-modified polypropylene,
(1) A homotype having a bigat softening point of 115 ° C or higher and a melting point of 150 ° C or higher (2) A copolymer of ethylene-propylene having a bigat softening point of 105 ° C or higher and a melting point of 130 ° C or higher (random copolymer type)
(3) A simple substance or a mixture obtained by acid-modified polymerization using an unsaturated carboxylic acid having a melting point of 110 ° C. or higher can be used.

  The adhesive layer 113 is a resin layer that firmly bonds the base material layer 112 and the barrier layer 114. Such interlayer adhesion can be performed by a dry lamination method, an extrusion lamination method, a coextrusion lamination method, a thermal lamination method, or the like.

  When laminating by the dry laminating method, polyester, polyethyleneimine, polyether, cyanoacrylate, urethane, organic titanium, polyetherurethane, epoxy, polyesterurethane, imide, isocyanate Various adhesives based on polyolefin, polyolefin, and silicone can be used.

  According to the present embodiment, the metal oxide fine particles 111 contained in the insulating layer 117 are excellent in heat resistance and strong, and are a highly insulating material. Therefore, the metal oxide fine particles 111 are also melted or crushed by heat and pressure during heat sealing. It is hard to do. Accordingly, when there is a burr on the positive electrode tab 123a and the negative electrode tab 123b, or when an electrode active material or a minute metal foreign matter scattered or mixed on the inner surface of the thermal adhesive layer 116, the burr, electrode active material or metal at the time of heat sealing is used. When foreign matter bites into the thermal bonding layer 116, these foreign matter is blocked by the insulating layer 117 on which the metal oxide fine particles 111 are deposited, and it is difficult for the foreign matter to reach the metal foil of the barrier layer 114, thereby preventing a decrease in insulation. Is done. Thereby, it can prevent that a short circuit generate | occur | produces via the lithium ion battery main body 122 containing the electrolyte solution inside the package 120 between the positive electrode tab 123a, the negative electrode tab 123b, and the barrier layer 114.

Further, the metal oxide fine particles 111 having an average particle size of 0.7 μm or less are deposited to form the insulating layer 117, and the thickness of the insulating layer 117 is X (μm). When Y (μm) is satisfied, by satisfying the following formula (1), the gap formed between the adjacent metal oxide fine particles 111 is reduced to reduce the volume of the metal oxide fine particles 111 contained in the insulating layer 117. The occupation rate can be increased. Thereby, the insulation of the insulating layer 117 can be further improved.

  The insulating layer 117 is formed by applying a treatment liquid in which a binder solution is added to an aqueous solution in which the metal oxide fine particles 111 are dispersed. Thereby, since a continuous process is possible and a water washing process is unnecessary, processing cost can be made cheap.

  Further, since the binder solution contains phosphoric acid, the phosphoric acid chemically melts part of the metal oxide fine particles 111. Thereby, the adhesiveness of the insulating layer 117 with respect to the adjacent barrier layer 114 is improved.

  Moreover, by forming the thickness of the insulating layer 117 to be 2 μm or less, the insulating layer 117 is secured and sufficient moldability is obtained.

Second Embodiment
FIG. 4 is a cross-sectional view showing a packaging material 110 according to the second embodiment. For convenience of explanation, the same parts as those in the first embodiment shown in FIGS. In the packaging material 110 of the present embodiment, a chemical conversion treatment layer 118 is provided on both surfaces of the barrier layer 114 and the surface of the insulating layer 117 on the heat bonding layer 116 side.

  The chemical conversion treatment layer 118 is an acid resistant film formed on the surface of the barrier layer 114 and the insulating layer 117 on which the metal oxide fine particles 111 are deposited. By providing the chemical conversion treatment layer 118, the corrosion resistance of the barrier layer 114 and the insulating layer 117 is improved, and the lamination strength with the adjacent resin layer is increased.

  The chemical conversion treatment layer 118 is formed by non-chromium chemical conversion treatment or chromium chemical conversion treatment. Examples of the non-chromium chemical conversion treatment include treatment with zirconium, titanium, zinc phosphate, and the like. Examples of the chromium-based chemical conversion treatment include chromate chromate treatment, phosphoric acid chromate treatment, and chromate treatment using an aminated phenol polymer.

  For the chromate chromate treatment, a chromic acid compound such as chromium nitrate, chromium fluoride, chromium sulfate, chromium acetate, chromium oxalate, chromium biphosphate, chromic acetyl acetate, chromium chloride, potassium sulfate chromium is used.

  Phosphate compounds such as sodium phosphate, potassium phosphate, ammonium phosphate and polyphosphoric acid are used for the phosphoric acid chromate treatment.

  For the chromate treatment using the aminated phenol polymer, an aminated phenol polymer comprising repeating units represented by the following general formulas (1) to (4) is used.

  In formulas (1) to (4), X represents a hydrogen atom, a hydroxyl group, an alkyl group, a hydroxyalkyl group, an allyl group or a benzyl group. R1 and R2 represent a hydroxyl group, an alkyl group, or a hydroxyalkyl group. R1 and R2 may be the same.

  In the formulas (1) to (4), examples of the alkyl group represented by X, R1, and R2 include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and a tert-butyl group. C1-C4 linear or branched alkyl groups, such as group, are mentioned.

  Examples of the hydroxyalkyl group represented by X, R1, and R2 include a hydroxymethyl group, a 1-hydroxyethyl group, a 2-hydroxyethyl group, a 1-hydroxypropyl group, a 2-hydroxypropyl group, and a 3-hydroxypropyl group. Group, 1-hydroxybutyl group, 2-hydroxybutyl group, 3-hydroxybutyl group, 4-hydroxybutyl group and the like, and a linear or branched alkyl group having 1 to 4 carbon atoms substituted with one hydroxy group Is mentioned.

  The number average molecular weight of the aminated phenol polymer composed of the repeating units represented by the formulas (1) to (4) is, for example, about 500 to about 1,000,000, preferably about 1000 to about 20,000.

  These chemical conversion treatments may be performed alone or in combination of two or more chemical conversion treatments. Furthermore, these chemical conversion treatments may be carried out using one kind of compound alone, or may be carried out using a combination of two or more kinds of compounds. Among these, chromic acid chromate treatment is preferable, and chromate treatment combining a chromic acid compound, a phosphoric acid compound, and an aminated phenol polymer is more preferable.

The amount of the acid-resistant film formed on the surfaces of the barrier layer 114 and the insulating layer 117 in the chemical conversion treatment is not particularly limited. For example, a chromate treatment is performed by combining a chromic acid compound, a phosphoric acid compound, and an aminated phenol polymer. In some cases, the chromic acid compound is about 0.5 to about 50 mg, preferably about 1.0 to about 40 mg, and the phosphorus compound is about 0.5 to about 50 mg in terms of phosphorus per 1 m ² of the surface of the metal layer. It is desirable to contain 50 mg, preferably about 1.0 to about 40 mg, and about 1 to about 200 mg, preferably about 5.0 to 150 mg of aminated phenol polymer.

  In the chemical conversion treatment, a solution containing a compound used for forming an acid-resistant film is applied to the surface of the barrier layer 114 or the insulating layer 117 by a bar coating method, a roll coating method, a gravure coating method, a dipping method, etc. The heating is performed so that the temperature of the layer 114 is about 70 to 200 ° C. In addition, before the chemical conversion treatment is performed on the barrier layer 114, the barrier layer 114 may be previously subjected to a degreasing treatment by an alkali dipping method, an electrolytic cleaning method, an acid cleaning method, an electrolytic acid cleaning method, or the like. By performing the degreasing process in this way, it is possible to perform the chemical conversion process on the surface of the barrier layer 114 more efficiently.

  According to the present embodiment, the surface of the insulating layer 117 on the side of the thermal adhesive layer 116 is subjected to a chromium-based chemical conversion treatment or a non-chromium-based chemical conversion treatment, thereby improving the corrosion resistance and adhesion (wetting properties) of the insulating layer 117. Thus, the lamination strength is improved between the insulating layer 117 and the adjacent layer.

  In the embodiment, different layers may be interposed between the layers. Any one of the chemical conversion treatment layers 118 may be omitted. Moreover, although the lithium ion battery 121 is described, an electrochemical cell body other than the lithium ion battery body 122 may be packaged with a package 120 made of the packaging material 110 to produce an electric cell other than the lithium ion battery 121. .

  For example, the electrochemical cell includes a nickel metal hydride battery, a nickel cadmium battery, a lithium metal primary battery or secondary battery, a chemical battery such as a lithium polymer battery, an electric double layer capacitor, a capacitor, and an electrolytic capacitor in addition to a lithium ion battery. Here, the electrochemical cell body is a positive electrode composed of a positive electrode active material and a positive electrode current collector before enclosing packaging material, a negative electrode composed of a negative electrode active material and a negative electrode current collector, and an electrolyte filled between the positive electrode and the negative electrode. And all electric device elements that generate electric energy, such as a cell (power storage unit) including electrode terminals connected to a positive electrode and a negative electrode in the cell.

  Next, the action and effect of the present invention will be specifically described using examples and comparative examples. In this experiment, an insulating layer 117 was formed on the upper surface of the barrier layer 114 constituting the electrochemical cell packaging material 110, and the insulating properties, laminate strength, and moldability were evaluated.

[Preparation of packaging materials for electrochemical cells]
The electrochemical cell packaging material 110 according to Example 1 was obtained by applying a treatment liquid in which a binder solution was added to an aqueous solution in which metal oxide fine particles 111 were dispersed on both sides of aluminum (thickness 35 μm) as a barrier layer 114. An insulating layer 117 having a thickness of 1 μm was formed by drying. At this time, aluminum oxide having an average particle diameter of 0.01 μm (the average particle diameter was calculated by measuring the size of the metal oxide fine particles in a photograph using a transmission electron microscope) was used for the metal oxide fine particles 111. Using. In addition, when the treatment liquid is obtained by dispersing the metal oxide fine particles 111 in an aqueous solution at a weight concentration of 30% and the weight part of the aqueous solution in which the metal oxide fine particles 111 are dispersed is 10, the amount of phosphoric acid contained in the binder solution. The weight part was 0.9, and the other resin weight parts were 0.1. Next, a stretched nylon film (thickness 15 μm) as the base material layer 112 is bonded by a dry lamination method through a two-component curable polyurethane adhesive, and acid-modified polypropylene (thickness 20 μm) is formed on the upper surface of the insulating layer 117. And polypropylene (thickness 15 μm) were laminated by a melt coextrusion method to form an acid-modified polyolefin layer 115 and a thermal adhesive layer 116.

  The electrochemical cell packaging material 110 according to the second embodiment has the same layer configuration except for the electrochemical cell packaging material 110 according to the first embodiment and the insulating layer 117. The insulating layer 117 of the packaging material 110 for an electrochemical cell according to Example 2 was formed using aluminum oxide having an average particle diameter of 0.01 μm and a layer thickness of 2 μm.

  The electrochemical cell packaging material 110 according to Example 3 has the same layer configuration as the electrochemical cell packaging material 110 according to Example 1 except for the insulating layer 117. The insulating layer 117 of the packaging material 110 for an electrochemical cell according to Example 2 was formed using aluminum oxide having an average particle diameter of 0.01 μm and a layer thickness of 3 μm.

  The electrochemical cell packaging material 110 according to the fourth embodiment has the same layer configuration except for the electrochemical cell packaging material 110 according to the first embodiment and the insulating layer 117. The insulating layer 117 of the packaging material 110 for an electrochemical cell according to Example 4 was formed using aluminum oxide having an average particle diameter of 0.3 μm and a layer thickness of 1 μm. The average particle diameter of aluminum oxide was measured with a laser diffraction / scattering particle size distribution analyzer (trade name: LA920, manufactured by Horiba, Ltd.).

  The electrochemical cell packaging material 110 according to the fifth embodiment has the same layer configuration except for the electrochemical cell packaging material 110 according to the first embodiment and the insulating layer 117. The insulating layer 117 of the packaging material 110 for an electrochemical cell according to Example 6 was formed using aluminum oxide having an average particle diameter of 0.3 μm and a layer thickness of 2 μm. The average particle diameter of aluminum oxide was measured with a laser diffraction / scattering particle size distribution analyzer (trade name: LA920, manufactured by Horiba, Ltd.).

  The electrochemical cell packaging material 110 according to the sixth embodiment has the same layer configuration except for the electrochemical cell packaging material 110 according to the first embodiment and the insulating layer 117. The insulating layer 117 of the packaging material 110 for an electrochemical cell according to Example 6 was formed using aluminum oxide having an average particle diameter of 0.7 μm and a layer thickness of 2 μm. The average particle diameter of aluminum oxide was measured with a laser diffraction / scattering particle size distribution analyzer (trade name: LA920, manufactured by Horiba, Ltd.).

In the electrochemical cell packaging material 110 according to the seventh embodiment, a chemical conversion treatment layer 118 is provided on the upper surface of the insulating layer 117 of the electrochemical cell packaging material 110 according to the first embodiment. In the chemical conversion treatment, a treatment liquid composed of a phenol resin, a chromium fluoride compound, and phosphoric acid was applied as a treatment liquid by a roll coating method, and baked under conditions where the film temperature was 180 ° C. or higher. Here, the coating amount of chromium was 10 mg / m ² (dry weight).

[Comparative Example 1]
The electrochemical cell packaging material according to Comparative Example 1 was not provided with the insulating layer 117 according to Example 1. That is, a chemical conversion treatment layer 118 is provided on both surfaces of aluminum (40 μm thickness) as a barrier layer, and a stretched nylon film as a base material layer 112 is provided on one surface with a two-component curable polyurethane adhesive in a dry lamination method. Then, acid-modified polypropylene (thickness 20 μm) and polypropylene (thickness 15 μm) were laminated on the other surface by a melt coextrusion method to form an acid-modified polyolefin layer and a thermal adhesive layer. The chemical conversion treatment was performed in the same manner as in Example 7.

[Comparative Example 2]
The electrochemical cell packaging material according to Comparative Example 2 has the same layer structure as the electrochemical cell packaging material according to Example 1 except for the insulating layer. The insulating layer of the packaging material for electrochemical cells according to Comparative Example 2 was formed using aluminum oxide having an average particle diameter of 1.0 μm and a layer thickness of 1 μm. The average particle diameter of aluminum oxide was measured with a laser diffraction / scattering particle size distribution analyzer (trade name: LA920, manufactured by Horiba, Ltd.).

[Comparative Example 3]
The electrochemical cell packaging material according to Comparative Example 3 has the same layer structure as the electrochemical cell packaging material according to Example 1 except for the insulating layer. The insulating layer of the packaging material for electrochemical cells according to Comparative Example 3 was formed using aluminum oxide having an average particle diameter of 1.0 μm and a layer thickness of 2 μm. The average particle diameter of aluminum oxide was measured with a laser diffraction / scattering particle size distribution analyzer (trade name: LA920, manufactured by Horiba, Ltd.).

[Comparative Example 4]
The electrochemical cell packaging material according to Comparative Example 4 has the same layer structure as the electrochemical cell packaging material according to Example 1 except for the insulating layer. The insulating layer of the packaging material for an electrochemical cell according to Comparative Example 4 was formed using aluminum oxide having an average particle diameter of 0.01 μm and a layer thickness of 5 μm. The average particle diameter of aluminum oxide was calculated by measuring the size of metal oxide fine particles with a photograph using a transmission electron microscope.

[Comparative Example 5]
The electrochemical cell packaging material according to Comparative Example 5 has the same layer structure as the electrochemical cell packaging material according to Example 1 except for the insulating layer. The insulating layer of the packaging material for electrochemical cells according to Comparative Example 5 was formed to a thickness of 1 μm using aluminum oxide having an average particle size of 0.7 μm. The average particle diameter of aluminum oxide was measured with a laser diffraction / scattering particle size distribution analyzer (trade name: LA920, manufactured by Horiba, Ltd.).
[Evaluation of insulation]

  The insulation was evaluated by cutting the packaging material for electrochemical cells according to Examples 1 to 7 and Comparative Examples 1 to 5 into 40 mm × 120 mm strips, and then the aluminum tab (30 mm × 100 mm) and the polypropylene side of the packaging material. The surface was brought into contact with the wire (inner diameter: 25.4 μm) while being heat-sealed at 190 ° C. with a heat seal pressure of 1.0 MPa and pressed by a heat seal bar (width 30 mm).

  At this time, the time during which the wire was bitten into the acid-modified polypropylene and polypropylene by pressing of the heat seal bar and the insulation was lowered between the aluminum tab and the aluminum of the packaging material was measured. The results are shown in Table 1. It should be noted that the time for the insulation to decrease is the time (seconds) until the resistance value reaches 100 MΩ or less after the voltage of 100 V is continuously applied between the aluminum tab and the aluminum of the packaging material after heat sealing is started. Say.

  As shown in Table 1, the packaging materials according to Examples 1 to 7 did not cause a short circuit even after 60 seconds. Thereby, the packaging materials according to Examples 1 to 7 are Comparative Example 1 in which the insulating layer 117 is not formed, and Comparative Examples 2 and 3 in which the insulating layer is formed using aluminum oxide having an average particle size larger than 0.7 μm. It was found that the insulation was superior.

[Evaluation of corrosion resistance]
The corrosion resistance was evaluated by changing the laminate strength between the barrier layer 114 and the acid-modified polyolefin layer 115 before and after being immersed in the electrolyte solution of the packaging material for electrochemical cells according to Examples 1 to 7 and Comparative Examples 1 to 5. Was measured.

  First, the electrochemical cell packaging materials according to Examples 1 to 7 and Comparative Examples 1 to 5 were cut into two pieces each having a length of 15 mm × 250 mm, and then one of them was subjected to 85 ° C. electrolytic solution (ethylene carbonate: diethyl carbonate: 1 mol of lithium hexafluorophosphate was added to a solution of dimethyl carbonate = 1: 1: 1) for 24 hours.

  Next, the strip which is immersed in the electrolytic solution and the strip which is not immersed in the electrolytic solution are used as a barrier layer 114 by using a tensile tester (manufactured by Shimadzu Corporation, AGS-50D (trade name)). And acid-modified polypropylene which is the acid-modified polyolefin layer 115 were peeled in the longitudinal direction at a speed of 50 mm / min. At this time, the strength at the time of peeling was measured to obtain the laminate strength (N / 15 mm) of the barrier layer 114 and the acid-modified polyolefin layer 115. The results are shown in Table 2.

As shown in Table 2, the packaging material for electrochemical cells according to Examples 1 to 7 showed no significant decrease in laminate strength after immersion of the electrolytic solution.
[Evaluation of moldability]

  The moldability was evaluated by cutting the electrochemical cell packaging materials according to Examples 1 to 7 and Comparative Examples 1, 4, and 5 into 80 mm × 120 mm each, and then molding metal molds (35 mm × 50 mm) (female) Mold) and a corresponding mold (male mold), and cold-molded to a depth of 5.0 mm at 0.1 MPa. How many of the 5 sheets are on the surface of the packaging material on the side of the thermal adhesive layer 116. Whether or not pinholes were generated was visually observed. The results are shown in Table 3.

  As shown in Table 3, in the electrochemical cell packaging materials according to Examples 1, 2, 4 to 7, no occurrence of pinholes was observed (◯). Further, only one pinhole was observed in the electrochemical cell packaging material according to Example 3 (Δ). In the electrochemical cell packaging material according to Comparative Example 4, pinholes were observed in four sheets (×).

  INDUSTRIAL APPLICABILITY The present invention can be used as a package for packaging chemical batteries such as nickel metal hydride batteries, nickel cadmium batteries, lithium metal primary batteries or secondary batteries, lithium polymer batteries, and electric double layer capacitors, capacitors, and electrolytic capacitors.

DESCRIPTION OF SYMBOLS 110 Packaging material 111 Metal oxide fine particle 112 Base material layer 113 Adhesion layer 114 Barrier layer 115 Acid-modified polyolefin layer 116 Thermal adhesion layer 117 Insulation layer 118 Chemical conversion treatment layer 120 Packaging body 120a Storage part 120b Lid part 121 Lithium ion battery 122 Lithium ion Battery body 123a Positive electrode tab 123b Negative electrode tab

Claims (3)

A base layer made of a resin film, a thermal adhesive layer made of a thermoadhesive resin arranged in the innermost layer, a barrier layer made of a metal foil arranged between the base material layer and the thermal adhesive layer, An insulating layer formed by laminating a plurality of metal oxide fine particles in three or more layers on the surface of the barrier layer on the side of the thermal adhesive layer The insulating layer is formed by applying a treatment liquid in which the metal oxide fine particles are dispersed in a binder solution, the binder solution contains phosphoric acid, and the average particle diameter of the metal oxide fine particles is 0.00. Electricity characterized by satisfying the following formula (1) when the film thickness is 7 μm or less, the film thickness of the insulating layer is X (μm), and the average particle diameter of the metal oxide fine particles is Y (μm): Packaging material for chemical cells.

  The packaging material for an electrochemical cell according to claim 1, wherein the insulating layer has a thickness of 2 μm or less.   3. The packaging material for an electrochemical cell according to claim 1, wherein a surface of the insulating layer on the heat bonding layer side is subjected to a chromium-based chemical conversion treatment or a non-chromium-based chemical conversion treatment.

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