JP6131559B2 - Packaging materials for electrochemical cells - Google Patents

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 main body such as an electrolyte and a separator, and the electrode tab connected to the positive electrode current collector and the negative electrode current collector of the electrochemical cell main body is sandwiched by the package at the thermal bonding portion. It is extended outside.

  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 configured by stacking at least a barrier layer made of a metal foil, wherein a plurality of barium sulfate fine particles are deposited on the surface of the barrier layer on the side of the thermal adhesive layer. It is characterized in that an insulating layer is formed.

  According to this configuration, the barium sulfate 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 barium sulfate fine particles 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 blocked by the insulating layer on which barium sulfate is deposited, so that it is difficult to reach the metal foil of the barrier layer, and the deterioration of the insulating property is prevented.

  According to the present invention, in the packaging material for an electrochemical cell having the above-described configuration, the insulating layer is formed by applying a treatment liquid in which the barium sulfate 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 insulating layer has improved adhesion (wetting property) to the adjacent resin.

  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 (wetting properties) of the insulating layer are further improved.

  According to the present invention, the barium sulfate 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 barium sulfate 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.

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 permeable 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 a plurality of barium sulfate fine particles 111. The barium sulfate fine particles 111 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. 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 barium sulfate 111111 is 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. . 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 barium sulfate fine particles 111 are preferably particles having an average particle size of 0.01 μm or more and 2.0 μm or less. Thereby, the gap formed between the adjacent barium sulfate fine particles 111 is reduced, and the volume occupation ratio of the barium sulfate 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. Moreover, it is preferable that the thickness of an insulating layer is 0.1 micrometer or more and 10 micrometers or less. Sufficient insulation is obtained by having a thickness of 20 μm or more. Moreover, by setting it as the thickness of 10 micrometers or less, insulation property is ensured and sufficient moldability is obtained.

  In addition, it becomes easy to deposit the barium sulfate fine particles 111 on the upper surface of the barrier layer 114 by using the spherical barium sulfate fine particles 111. In addition to the spherical shape, non-spherical fine particles such as a plate shape and a needle shape may be contained.

  In addition, the average particle diameter of the barium sulfate fine particles 111 referred to in the present invention is an average value of diameters (sphere converted particle diameters) when the barium sulfate fine particles 111 are converted into spheres having the same volume. The average particle diameter of the barium sulfate fine particles 111 can be measured using a laser diffraction / scattering particle size distribution measuring apparatus. In addition, when the particle diameter is 0.01 μm or less, 200 or more arbitrary particles are extracted from the barium sulfate fine particles 111 taken in the photograph taken with a transmission electron microscope, each particle diameter is measured, and the average value is calculated. can do.

  Further, the thickness 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 barium sulfate fine particles 111. The height from the upper surface of the insulating layer 117 to the upper end of the barium sulfate fine particles 111 that partially protrude.

  The insulating layer 117 may be formed by mixing metal oxide fine particles in addition to the barium sulfate fine particles 111. Examples of the metal oxide fine particles include aluminum oxide, cerium oxide, titanium oxide, tin oxide, and zirconium oxide.

  The insulating layer 117 is formed by applying a treatment liquid in which the barium sulfate 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 barium sulfate 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.

  When the binder solution contains phosphoric acid, phosphoric acid chemically melts part of the barium sulfate 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.

  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 barium sulfate fine particles 111 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 barium sulfate 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 barium sulfate fine particles 111 contained in the insulating layer 117 are excellent in heat resistance and strong, and are a highly insulating material. Therefore, melting and crushing occur due to heat and pressure during heat sealing. hard. 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 adhesive layer 116, these foreign matter is blocked by the insulating layer 117 on which the barium sulfate fine particles 111 are deposited, and it is difficult to reach the metal foil of the barrier layer 114, thereby preventing a decrease in insulation. The 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, by forming the insulating layer 117 by depositing the barium sulfate fine particles 111 having an average particle diameter of 2.0 μm or less, the gap formed between the adjacent barium sulfate fine particles 111 is reduced and included in the insulating layer 117. The volume occupancy of the barium sulfate fine particles 111 can be increased. Thereby, the insulation of the insulating layer 117 can be further improved.

  Further, by forming the insulating layer 117 by applying a treatment liquid in which the barium sulfate fine particles 111 are dispersed in a binder solution, continuous treatment is possible and a water washing step is unnecessary, so that the treatment cost can be reduced. .

  In addition, when the binder solution contains phosphoric acid, the insulating layer 117 has improved adhesion (wetability) to the adjacent resin.

  In addition, by forming the insulating layer 117 to have a thickness of 0.1 μm or more and 10 μm or less, the insulating layer 117 is ensured in insulation 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 barium sulfate 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 and the laminate strength were evaluated.

[Preparation of packaging materials for electrochemical cells]
The packaging material 110 for an electrochemical cell according to Example 1 is obtained by applying a treatment solution obtained by adding a binder solution to an aqueous solution in which barium sulfate fine particles 111 are dispersed on both surfaces of aluminum (thickness: 40 μm), which is a barrier layer 114, and then drying. Thus, an insulating layer 117 having a thickness of 1 μm was formed. At this time, the average particle diameter of the barium sulfate fine particles 111 was 0.095 μm (the average particle diameter was calculated by measuring the size of the barium sulfate fine particles in a photograph using a transmission electron microscope). In addition, the treatment liquid has the weight of phosphoric acid contained in the binder solution when the barium sulfate fine particles 111 are dispersed 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. Parts were 0.9, and other resin parts by weight 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.

  In the electrochemical cell packaging material 110 according to the second embodiment, an insulating layer 117 having a thickness of 1 μm is formed similarly to the electrochemical cell packaging material 110 according to the first embodiment, and then the chemical conversion treatment layer 118 is formed on the upper surface of the insulating layer 117. Then, acid-modified polypropylene (thickness: 20 μm) and polypropylene (thickness: 15 μm) were laminated on the top surface of the chemical conversion treatment layer 118 by a melt coextrusion method to form an acid-modified polyolefin layer 115 and a thermal adhesive layer 116.

The chemical conversion treatment was performed by applying a solution comprising a phenol resin, a chromium fluoride compound, and phosphoric acid to the upper surface of the insulating layer 117 by a roll coating method, and baking it under conditions where the film temperature was 180 ° C. or higher. The application amount of chromium was 10 mg / m ² (dry weight).

  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. For the insulating layer 117 of the packaging material 110 for an electrochemical cell according to Example 3, a treatment liquid in which barium sulfate fine particles 111 having an average particle diameter of 0.2 μm were dispersed in a mixed liquid of phosphoric acid and aminated phenol was used. The average particle diameter of the barium sulfate fine particles was measured with a laser diffraction / scattering particle size distribution measuring apparatus (trade name: LA920, manufactured by Horiba, Ltd.).

[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, both surfaces of aluminum (40 μm thickness) as a barrier layer are subjected to chemical conversion treatment, and acid-modified polypropylene (thickness 20 μm) and polypropylene (thickness 15 μm) are melt-extruded from the surface subjected to the chemical conversion treatment. By laminating, an acid-modified polyolefin layer and a thermal adhesive layer were formed. The chemical conversion treatment was performed in the same manner as in Example 2.

[Evaluation of insulation]
The insulation evaluation was performed by cutting the packaging material for electrochemical cells according to Examples 1 to 3 and Comparative Example 1 into strips of 40 mm × 120 mm, and then aluminum tabs (30 mm × 100 mm) and the polypropylene side surface of the packaging material. Were brought into contact with each other while sandwiching a wire (inner diameter: 25.4 μm), and heat-sealed at a heat seal pressure of 0.2 MPa and 190 ° C. with 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 3 were not short-circuited even after 60 seconds. Thereby, it turned out that it is excellent in insulation compared with the comparative example 1 in which the insulating layer 117 is not formed.

[Evaluation of corrosion resistance]
The corrosion resistance was evaluated by measuring the change in the laminate strength between the barrier layer 114 and the acid-modified polyolefin layer 115 before and after immersing the electrochemical cell packaging material according to Examples 1 to 3 in the electrolytic solution. went.

  First, the packaging material for electrochemical cells according to Examples 1 to 3 was cut into two strips each having a size of 15 mm × 250 mm, and then one of them was subjected to an electrolytic solution (ethylene carbonate: diethyl carbonate: dimethyl carbonate = 1: 1) at 85 ° C. : 1 mol of lithium hexafluorophosphate was added to the solution of No. 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, Example 2 and Example 3 subjected to chemical conversion treatment had higher laminate strength than Example 1 not subjected to chemical conversion treatment.

  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 Barium sulfate microparticles 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 (5)

  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, A packaging material for an electrochemical cell constituted by laminating at least a layer, wherein an insulating layer in which a plurality of barium sulfate fine particles are laminated is provided on a surface of the barrier layer on the thermal adhesive layer side. And packaging material for electrochemical cells.   2. The packaging material for an electrochemical cell according to claim 1, wherein a part of the barium sulfate fine particles and a part of the metal foil are melted and bonded to the insulating layer.   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. 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, A method for producing a packaging material for an electrochemical cell comprising at least a laminate of a coating solution, wherein a treatment liquid in which barium sulfate fine particles are dispersed in a binder solution is applied to the surface of the barrier layer on the thermal adhesive layer side. A method for producing a packaging material for an electrochemical cell.   The method for producing a packaging material for an electrochemical cell according to claim 4, wherein the binder solution contains phosphoric acid.

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