KR20230073987A - Outer material for power storage device - Google Patents

Abstract

Provided is an outer packaging material for a power storage device, capable of efficiently releasing gas at high temperatures. The present invention provides an outer packaging material for a power storage device, comprising: a metal foil layer (4); a resin-made base material layer (2) provided on the outer surface side of the metal foil layer (4); and a heat-welded resin-made heat-welded layer (3) provided on the inner surface side of the metal foil layer (4), wherein the heat-welded layer (3) includes a sealing layer (30) disposed on the innermost surface thereof. The relationships of 20 N/15 mm < = Pa < = 65 N/15 mm and Pb/Pa < = 1/4 are satisfied, where in a state in which the sealing layers are heat-sealed, the sealing strength in a 100 ℃ atmosphere at the heat-sealed portion of the sealing layers is Pa and the sealing strength in a 130 ℃ atmosphere is Pb.

Description

Exterior material for electrical storage device {OUTER MATERIAL FOR POWER STORAGE DEVICE}

The present invention, for example, for mobile devices such as notebook personal computers, smart phones and tablet terminals, vehicle-mounted, fixed-type secondary batteries, particularly power storage devices such as lithium ion secondary batteries for mobile devices It relates to exterior materials for dragons and related technologies.

In recent years, with the thinning and weight reduction of mobile devices such as smart phones and tablet terminals, lithium ion secondary batteries mounted on them are formed by laminating exterior materials such as aluminum laminate sheets instead of conventional metal cans and cases. By using an exterior case (outer shell) formed by heat-sealing and sealing the parts, it can be processed into various shapes according to the usage conditions, improving versatility, and also reducing the thickness and weight.

In addition, the high performance of the mobile device itself is also rapidly progressing, and in order to maintain the function, a high capacity of a battery such as a secondary battery for a mobile device, that is, a high energy density is required as much as possible.

Accompanying such a high-capacity battery, heat generation from the battery, ignition, etc. are a concern, so preventive measures against ignition and the like are also important.

For example, in a lithium ion battery or the like, when the temperature of the battery rises and the electrolyte thermally decomposes, a combustible gas is generated, which may lead to ignition.

Conventionally, electrical storage devices (batteries) shown in Patent Literatures 1 and 2 below have been proposed as preventive measures against battery ignition. In the electrical storage device disclosed in Patent Document 1, a pressure release valve is separately attached to an external case, and when the pressure inside the battery rises due to a rise in temperature, the pressure release valve opens to release gas to lower the pressure and temperature to prevent ignition. are doing

Further, in the electrical storage device disclosed in Patent Literature 2, gas is released and ignition is prevented by peeling off and opening the thermally fused portion (heat seal portion) of the packaging material as an exterior case at a high temperature.

Japanese Patent No. 6540871 Japanese Unexamined Patent Publication No. 2019-29300

However, in the conventional power storage device disclosed in Patent Literature 1, there is a problem that the number of parts increases and productivity may decrease because a pressure release valve needs to be separately attached.

In addition, in the electrical storage device disclosed in Patent Literature 2, there is a problem that the outer case may be opened in a low temperature region before reaching a high temperature at which decomposition gas is generated, and degassing cannot be performed efficiently.

Preferred embodiments of the present invention have been made in view of the above-mentioned and/or other problems in the related art. A preferred embodiment of the present invention is one that can significantly improve existing methods and/or devices.

The present invention has been made in view of the above problems, and can efficiently release gas at high temperatures, sufficiently securing safety against ignition, etc., while reducing the number of parts and improving productivity. An exterior material for an electrical storage device and to provide related technologies.

Other objects and advantages of the present invention will become clear from the following preferred embodiments.

In order to solve the said subject, this invention is equipped with the following means.

[One]

A metal foil layer, a base material layer made of resin provided on the outer surface side of the metal foil layer, and a heat-sealed resin layer provided on the inner surface side of the metal foil layer, wherein the heat-sealed layer is disposed on the innermost surface As an exterior material for an electrical storage device containing a seal layer,

In a state where the yarn layers are heat-sealed, the yarn strength in the heat-sealed portion of the yarn layers in a 100 ° C. atmosphere is set to “Pa”, and the yarn strength in a 130 ° C. atmosphere is set to “Pb”,

20N/15mm≤Pa≤65N/15mm

of Pb/Pa≤1/4

A packaging material for an electrical storage device characterized in that it is configured so that a relationship is established.

[2]

The packaging material for an electrical storage device according to the preceding paragraph 1, wherein the heat-sealing layer is provided on the outer surface side of the sealing layer and includes a metal foil side layer having a melting point of 140°C or higher.

[3]

The packaging material for an electrical storage device according to the preceding item 1 or 2, wherein the seal layer includes a first seal layer and a second seal layer laminated on an outer surface side of the first seal layer and having a higher melting point than the first seal layer.

[4]

The packaging material for an electrical storage device according to any one of the preceding paragraphs 1 to 3, configured so that the relationship of Pb ≤ 5 N/15 mm is established.

[5]

The seal layer is composed of a resin compound obtained by adding a polyolefin compound having a melting point 15° C. or more lower than that of rPP as a modifier to a propylene-ethylene random copolymer (rPP),

The packaging material for electrical storage devices according to any one of the preceding paragraphs 1 to 4, wherein the amount of the modifier added is adjusted to 5 wt% to 50 wt% with respect to the resin compound.

[6]

An external case for an electrical storage device for sealing an electrical storage device main body to form an electrical storage device, comprising:

Equipped with the exterior material according to any one of the preceding paragraphs 1 to 5,

An exterior case for an electrical storage device characterized in that it is formed by heat-sealing the seal layers to each other.

[7]

The exterior case for an electrical storage device according to the preceding paragraph 6, wherein the heat-sealed portion of the seal layers is cohesively separated as the internal pressure rises.

[8]

an electrical storage device main body;

Provided with the exterior case described in the preceding paragraph 6 or 7,

The electrical storage device characterized in that the electrical storage device main body is sealed in the exterior case.

[9]

an electrical storage device main body;

Equipped with the exterior material according to any one of the preceding paragraphs 1 to 5,

The electrical storage device according to claim 1, wherein the electrical storage device main body is covered with the exterior material.

According to the packaging material for an electrical storage device of the invention [1], since the seal strength at high temperature is specified, when the internal pressure rises and reaches the high temperature range while sufficiently maintaining the seal (seal) property at room temperature and low temperature, the seal strength By lowering, degassing is performed efficiently, and inadequacy such as ignition due to lowering of pressure and temperature can be prevented. In particular, in addition to the yarn strength at a high temperature of about 130°C, the yarn strength at a slightly high temperature of about 100°C is clearly specified. By performing the removal smoothly, it is possible to reliably prevent occurrence of unexpected gas or the like. In addition, since there is no need to separately provide other parts such as a pressure release valve for degassing at high temperatures, the number of parts can be reduced and productivity can be improved accordingly.

According to the packaging material for electrical storage devices of invention [2], since the high-melting-point metal foil side layer exists on the outside of the seal layer in the heat-sealing layer, the position of the seal layer on the inside of the metal foil side layer at high temperature, that is, the desired It is opened reliably at the heat chamber position. For this reason, the degree of degassing can be accurately controlled, and also in this respect, occurrence of unexpected gas or the like can be reliably prevented.

According to the packaging material for electrical storage devices of the invention [3], resin pools easily occur in the heat seal portion at room temperature, and the sealing performance (sealability) at room temperature can be further improved by the generation of resin pools.

According to the exterior material for electrical storage devices of invention [4] [5], the above effect can be acquired more reliably.

According to the exterior case for electrical storage devices of invention [6] [7], the same effect as the above exterior material can be obtained.

According to the power storage device of invention [8] [9], the same effect as the above exterior material can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a cross-sectional view showing an exterior material for an electrical storage device as an embodiment of the present invention.
Fig. 2 is a cross-sectional view showing a power storage device fabricated using the packaging material of the embodiment.
Fig. 3 is an exploded perspective view showing the power storage device of the embodiment;
Fig. 4 is a graph showing the relationship between yarn strength and ambient temperature in each resin for seal layer.

1 is a cross-sectional view showing an exterior material 1 for an electrical storage device, which is an embodiment of the present invention. As shown in the same figure, this packaging material 1 for electrical storage devices is, in order from the top, substrate layer 2 / outer adhesive layer 52 / metal foil layer (barrier layer) 4 / inner adhesive layer 51 / It is constituted by a laminate (laminate sheet) in which a heat-sealing layer (sealant layer) 3 is laminated.

That is, this packaging material 1 for an electrical storage device includes a metal foil layer 4 composed of metal foil, an outer adhesive layer 52 provided on the outer surface side of the metal foil layer 4, and provided on the outer surface side of the outer adhesive layer 52. In addition, the substrate layer 2 made of heat-resistant resin as an outer layer, the inner adhesive layer 51 provided on the inner surface side of the metal foil layer 4, and the inner adhesive layer 51 provided on the inner surface side, further inner A heat-sealable layer (sealant layer) 3 made of a heat-sealable resin as a layer is provided.

Here, in this embodiment, in the exterior case 1 of the exterior case 65 of the electrical storage device 6, the substrate layer 2 is on the outside and the thermally fused layer 3 is on the inside. In this embodiment, when explaining the position of each layer constituting the packaging material 1 in terms of directions, the direction on the side of the substrate layer 2 is set to the outside and the heat-sealed layer in accordance with the inside and outside directions of the exterior case 65. (3) The direction on the side is called the inner side.

The substrate layer 2 is a heat-resistant resin, for example, a biaxially oriented polyamide film, a biaxially oriented polybutylene terephthalate (PBT) film, a biaxially oriented polyethylene terephthalate (PET) film, or a biaxially oriented polyethylene naphthalate ( PEN) film is preferably used. Among these, the polyamide film is not particularly limited, but for example, a 6-nylon film, a 6,6-nylon film, an MXD nylon film and the like can be suitably used.

In addition, it is preferable to set the thickness of the substrate layer 2 to 9 μm to 50 μm. That is, in the case where the substrate layer 2 is adjusted to this thickness, sufficient strength can be secured as the packaging material 1, and the stress at the time of molding such as elongation molding and drawing molding can be reduced. You can further improve your sexuality. A more preferable thickness of the substrate layer 2 is 9 μm to 30 μm. When the substrate layer 2 is a multi-layer, the total thickness is set to the thickness described above. In addition, when the base material layer 2 is a multilayer, the thickness of the adhesive which bonds a some layer together is also included in the said thickness.

The substrate layer 2 may be formed in a single layer or, as already stated, may be formed in a multi-layer. In the case of forming in a multilayer, for example, a multilayer composed of a polyester film/polyamide film (a multilayer composed of a PET film/nylon film, etc.) is exemplified.

In addition, the base layer 2 is a layer constituting the outer layer, and as a layer constituting the outer layer, in addition to the base layer 2, a protective layer bonded to the outside of the base layer 2, and a layer constituting the outer layer For bonding An adhesive layer etc. are mentioned.

In addition, as the substrate layer 2, a heat-resistant resin film that does not melt at the heat-sealing temperature at the time of heat-sealing the packaging material 1 is used. Specifically, it is preferable to use a resin having a melting point higher than 10°C, more preferably a resin having a melting point higher than 20°C, for all resins constituting the heat-sealed layer 3 (resin layers 31 to 33).

For the metal foil layer 4, a metal foil composed of aluminum (Al) foil, copper (Cu) foil, stainless steel (SUS) foil, titanium (Ti) foil, or nickel (Ni) foil is used alone, or two or more types of metal foil are stacked together. A combined cladding material or the like can be suitably used. Among them, as the metal foil layer 4, an aluminum foil can be suitably used. In particular, since the Al-Fe alloy foil containing 0.7% by mass to 1.7% by mass of Fe has excellent strength and malleability, good formability can be obtained.

The thickness of the metal thin layer 4 is preferably set to 20 μm to 100 μm. That is, when the thickness is 20 μm or more, pinhole generation during rolling when manufacturing metal foil can be prevented, and when the thickness is 100 μm or less, stress during molding such as extrusion molding and drawing molding can be reduced, resulting in formability. can improve

It is preferable to form a base layer on at least one of the inner and outer surfaces of the metal foil layer 4.

The base layer can be formed by chemical conversion treatment such as application treatment of a silane coupling agent or chromate treatment.

The thickness of the base layer is preferably set to 0.01 μm to 1 μm.

By forming the base layer in this way, the adhesive strength with the adhesive layers 51 and 52 provided on both the inner and outer surfaces of the metal foil layer 4 can be improved, and peeling of the adhesive layers 51 and 52 can be effectively prevented. there is. Further, corrosion of the surface of the metal foil due to contents (electrolyte of a battery, etc.) can be sufficiently prevented by chemical conversion treatment.

In the case of forming a base layer by a chemical conversion film (conversion film), the chemical conversion film may be selected in combination with the adhesive layers 51 and 52, for example, a chromic acid treatment film, a phosphoric acid film A coating by chromate treatment, a coating by zinc phosphate treatment, a coating by non-chromate treatment using zirconium or titanium as a metal component to replace Cr, and an oxide coating by boehmite treatment can be suitably used.

The base layer 2 is attached to the outer surface of the metal foil layer 4 via the outer adhesive layer 52 to integrate the lamination.

The adhesive constituting the outer adhesive layer 52 for adhering the substrate layer 2 and the metal foil layer 4 includes, for example, a polyurethane-based polyol, a polyester-based polyol, a polyether-based polyol, and a polyester-urethane-based polyol. A two-component curing type adhesive or the like composed of a first liquid composed of one or two or more types of polyols selected from the group and a second liquid (curing agent) composed of isocyanate can be used.

The thickness of this outer adhesive layer is preferably set to 2 μm to 5 μm.

As the adhesive constituting the inner adhesive layer 51 provided on the inner surface of the metal foil layer 4, polyurethane-based resins, acrylic-based resins, epoxy-based resins, polyolefin-based resins, elastomer-based resins, fluorine-based resins, and acid-modified polypropylene resins are used. An adhesive containing one or more types can be suitably used, and among these, it is preferable to use an adhesive composed of a polyurethane composite resin based on an acid-modified polyolefin.

It is preferable to set the thickness of the inner adhesive layer 51 to 2 μm to 5 μm.

In addition, even when the outer layer described above is composed of a multilayer (including a case where the base material layer is a multilayer), it is preferable to use the same type of adhesive.

In this embodiment, the heat-sealing layer 3 includes the seal layer 30 on at least the innermost surface (lowest end in FIG. 1). In the present invention, the heat-sealing layer 3 may be constituted only by the seal layer 30. The seal layer 30 itself may be composed of a single layer or may be composed of a multilayer structure of two or more layers. Further, the heat-sealing layer 3 may have a multilayer structure in which a metal foil side layer 33 is laminated on the outer surface side in addition to the seal layer 30.

When the heat-sealing layer 3 is constituted by a single-layer seal layer 30, a single-layer film can be used, and when the heat-sealing layer 3 is formed in a multilayer structure, a co-extruded product or the like Laminated (multilayer) films may be used.

In this embodiment, the heat-sealing layer 3 is constituted by a three-layer laminated film. That is, the seal layer 30 in the heat-sealed layer 3 is composed of the first seal layer 31 disposed on the inner surface side and the second seal layer 32 laminated on the outer surface side of the first seal layer 31. In addition, by laminating the metal foil side layer 33 on the outer surface side of the sealing layer 30, the thermally fused layer 3 having a three-layer structure as a whole is formed.

In this embodiment, it is preferable to set the thickness of the heat sealing layer 3 to 20 μm to 100 μm. That is, when this thickness is less than 20 μm, sufficient insulation cannot be obtained, and when it exceeds 100 μm, the sealing time becomes long and becomes uneconomical.

In addition, when the heat-sealing layer 3 is constituted by the three-layer structure of the first seal layer 31, the second seal layer 32, and the metal foil side layer 33 as in the present embodiment, the first seal layer 31 It is preferable to set the thickness as "T1", the thickness of the second thread layer 32 as "T2", and the thickness of the metal foil side layer 33 as "T3" to establish the following relationship.

T1:T2:T3 = (1 to 3): (4 to 8): (1 to 3)

A propylene-ethylene random copolymer (rPP) can be used as a resin constituting the seal layer 30. The propylene-ethylene random copolymer (rPP) is a propylene-ethylene copolymer (random PP) or a propylene-butene copolymer (random PP) obtained by randomly copolymerizing propylene with ethylene or butene (olefin excluding propylene). As the random PP, metallocene-based polypropylene (m-PP) polymerized using a metallocene catalyst and Ziegler-nata-based polypropylene (zn-PP) polymerized using a Ziegler-Natta catalyst can be suitably used.

As a modifier for m-PP and zn-PP, 5% to 50% of linear low-density polyethylene (LLDPE), LLDPE (m-LLDPE) made with a metallocene catalyst, or polyolefin elastomer including ethylene propylene rubber It is desirable to add A more preferable addition amount is 10% to 40%.

The modifier has a lower melting point than the main resin constituting the seal layer 30, and the softening of the seal layer 30 can be enhanced by incorporating this modifier into the seal layer 30. As the modifier, the softening property can be sufficiently improved by using a modifier made of a polyolefin compound that is 15° C. or more lower than rPP.

When the seal layer 30 is composed of multiple layers, it is preferable to include a modifier in at least one layer, more preferably in the first seal layer 31.

rPP as a base has a melting point calculated by differential scanning calorimetry of 120°C to 140°C.

The above-described rPP exhibits a decrease in yarn strength at 110° C. to 130° C., and the yarn easily peels off, and the yarn strength is maintained at temperatures below that. When the temperature of the battery made of the packaging material 1 of the present embodiment rises, gas is generated due to volatilization of the electrolyte and the like, the pressure inside the battery rises around 130°C, and the case starts to expand. The above-described temperature range of the decrease in yarn strength corresponds to a temperature higher than the assumed use temperature range of the battery and lower than the temperature at which expansion begins. Therefore, when the temperature of the battery rises rapidly and the internal pressure starts to rise due to the generation of gas, the seal is peeled off and the case is opened. When the case is opened, the gas is released gently, preventing the case from bursting or igniting.

The aforementioned rPP derived from the metaceron catalyst has a high uniformity of molecular weight and is highly effective in reducing yarn strength at a desired temperature.

Among the seal layers 30 in this embodiment, it is preferable to use a resin having a higher melting point than the first seal layer 31 for the second seal layer 32 . In addition, the melting point difference between the first seal layer 31 and the second seal layer 32 is preferably set to 5°C to 10°C, more preferably set to 6°C to 8°C.

Specifically, rPP with a melting point of 110 ° C to 140 ° C, preferably 120 ° C to 130 ° C is used as the main resin for the first seal layer 31, and this resin has a melting point of 90 ° C to 110 ° C. It is preferable to add m-LLDPE (metallocene-catalyzed linear low-density polyethylene) as a modifier. It is good to adjust this addition amount to 5 wt% - 60 wt%, and it is good to adjust it to 10 wt% - 40 wt% more suitably. By adding the modifier to the first seal layer 31 in this way, the softness of the first seal layer 31 can be improved.

As the second seal layer 32, rPP with a melting point of 120 ° C to 150 ° C, preferably 125 ° C to 135 ° C is used as the main resin, and m-LLDPE with a melting point of 90 ° C to 110 ° C is added to this resin. It is good to add as a modifier. It is good to adjust this addition amount to 5wt% - 60wt%, and it is good to adjust it to 10wt% - 40wt% more suitably. If the modifier is added to the first seal layer 31, it is not necessarily added to the second seal layer 32 and may not be added.

When there are a plurality of sealing layers in the packaging material 1, when manufacturing an exterior case for a battery, a thermally fused layer 3 so that the case is opened at the sealing portion between the first sealing layers 31 of the two heat-sealed packaging materials 1 ) is preferably designed, and peeling of the heat-sealed layer 3 does not occur before the yarn between the first seal layers 31 is peeled off. When delamination occurs in the heat-sealed layer 3, there is a possibility that the gas generated inside the battery may become difficult to escape under a high-temperature environment.

In addition, as will be described later in detail, the seal layer 30 has a seal strength unique to the present invention when the seal layers 30 are heat-sealed to each other.

As the resin constituting the metal foil side layer 33, a propylene-ethylene random copolymer (rPP), a polypropylene block copolymer (bPP), a homopropylene (hPP), or the like can be suitably used. In addition, by forming the metal foil side layer 33 with an ethylene-propylene random copolymer, strong bonding force to the metal foil layer 4 can be obtained.

As the metal foil side layer 33, it is preferable to use a resin having a melting point of 140°C or higher, more preferably a resin with a melting point of 160°C or lower, even more preferably a resin with a melting point of 150°C or lower, still more preferably a resin with a melting point of 145°C or lower. It is good to use.

Specifically, as the metal foil side layer 33, a melting point of 130 ° C. to 150 ° C., preferably rPP with a melting point of 135 ° C. to 145 ° C. is used as the main resin, and PO with a melting point of 130 ° C. or higher is added to this resin It is good to add a stormer as a modifier. It is good to adjust this addition amount to 10wt% - 30wt%, and it is good to adjust it to 15wt% - 25wt% more suitably. By adding elastomer to the metal foil side layer 33, flexibility is obtained and adhesion to the inner adhesive layer 51 is improved. If the addition amount of the modifier is too large, the electrolyte solution resistance is poor, and if the amount is too small, sufficient flexibility cannot be obtained.

In this embodiment, an intermediate layer may be formed between the real layer 30 and the metal foil side layer 33. As the intermediate layer, either a homopolymer of propylene or a copolymer containing propylene and a copolymerization component other than propylene in the copolymerization component may be used, or a mixture of a plurality of types of polymers may be used. In particular, it is preferable to configure the intermediate layer with a block polypropylene (bPP) film. Further, in the middle layer, when the same propylene-based resin as the seal layer 30 is mixed, the adhesion between the seal layer 30 and the intermediate layer is improved. In addition, either of a single layer and a multi-layer may be sufficient as an intermediate|middle layer. In addition, by forming an intermediate layer, electrical insulation and impact resistance can be improved.

Furthermore, in this embodiment, it is preferable to contain a lubricant in the seal layer 30 of the heat-sealing layer 3, especially the first seal layer 31.

Examples of the lubricant include saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylolamides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid ester amides, and aromatic bisamides.

Examples of saturated fatty acid amides include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, and hydroxystearic acid amide.

Examples of unsaturated fatty acid amides include oleic acid amide and erucic acid amide.

Examples of substituted amides include N-oleyl palmitic acid amide, N-stearyl stearic acid amide, N-stearyl oleic acid amide, N-oleyl stearic acid amide and N-stearyl erucic acid amide.

Moreover, methylol stearic acid amide can be illustrated as methylolamide.

Further, examples of the saturated fatty acid bisamide include methylene bis stearic acid amide, ethylene bis capric acid amide, ethylene bis lauric acid amide, ethylene bis stearic acid amide, ethylene bishydroxystearic acid amide, ethylene bisbehenic acid amide, hexamethylene bis stearic acid amide, and hexamethylene Bisbehenic acid amide, hexamethylene hydroxystearic acid amide, N,N'-distearyladipic acid amide, and N,N'-distearylsebacic acid amide can be exemplified.

Examples of unsaturated fatty acid bisamides include ethylenebisoleic acid amide, ethylenebiserucic acid amide, hexamethylenebisoleic acid amide, N,N'-dioleyladipic acidamide, and N,N'-dioleylsebacic acid amide. .

Moreover, stearoamide ethyl stearate can be illustrated as fatty acid ester amide.

Examples of the aromatic bisamide include m-xylenebisstearic acid amide, m-xylenebishydroxystearic acid amide, and N,N'-cystearylisophthalic acid amide.

Moreover, in this embodiment, it is preferable to add an antiblocking agent (AB agent) to seal layer 30.

As the antiblocking agent, acrylic resin beads, aluminum silicate, calcium carbonate, barium carbonate, titanium oxide, talc, kaolin and the like can be suitably used.

In addition, as an antiblocking agent, it is good to use the thing with an average particle diameter of 0.1 micrometer - 10 micrometers, More preferably, it is good to use the thing with 1 micrometer - 5 micrometers.

In addition, it is preferable to set the addition amount of the antiblocking agent to 100 ppm to 5000 ppm in mass units.

By incorporating an antiblocking agent (particles) into the first seal layer 31 of the heat-sealing layer 3, minute protrusions are formed on the surface of the first seal layer 31 to reduce the contact area between the films and seal film. Blocking of each other can be suppressed. In addition, by containing an antiblocking agent (particles) together with the lubricant, the activity at the time of molding can be further improved.

The packaging material 1 for electrical storage devices of the present embodiment configured as described above is molded into a predetermined shape by cold forming such as deep drawing molding or extrusion molding in a sheet form or as needed as an exterior case for an electrical storage device. is to use

For example, FIGS. 2 and 3 are cross-sectional and exploded perspective views showing the electrical storage device 6 manufactured using the packaging material 1 of this embodiment. As shown in both figures, this electrical storage device 6 is a lithium ion secondary battery. In this embodiment, an exterior case 65 is constituted by a tray member 64 obtained by molding the exterior material 1 and a cover member 60 constituted by the planar (sheet-like) exterior material 1. . Thus, the electrical storage device body portion (electrochemical element, etc.) 61 having a roughly rectangular parallelepiped shape is accommodated in the accommodating concave portion of the tray member 64 obtained by molding the packaging material 1 of the present invention, and the electrical storage device body portion On top of 61, the cover member 60 (exterior material 1) of the present invention is disposed with the heat-sealing layer 3 side inward (lower), and at the outer periphery of the cover member 60 The sealing layer 30 (first sealing layer 31) of the heat-sealing layer 3 and the sealing layer 30 of the heat-sealing layer 3 at the flange portion (periphery for sealing) 641 of the tray member 64 (First seal layer 31) is sealed by heat seal, seal layers 30 (first seal layers 31 to each other) are sealed by heat seal, thereby forming electrical storage device 6 has been In addition, the inner surface of the accommodating concave of the tray member 64 is made of the thermally fused layer 3, and the outer surface of the accommodating concave is the substrate layer 2 side.

In FIG. 2 , “69” of the reference numeral is a heat seal portion where the outer periphery of the cover member 60 and the flange portion (periphery for sealing) 641 of the tray member 64 are bonded (welded). In addition, in the electrical storage device 6, the front end of the tab lead connected to the electrical storage device main body 61 is led out of the exterior case 65, but illustration is omitted.

Although it is not specifically limited as the electrical storage device body part 61, For example, a battery main body part, a capacitor main body part, a capacitor main body part, etc. are mentioned.

Here, in the present embodiment, when the seal layers 30 of the packaging material 1 are heat-sealed to each other, the seal strength in the heat-sealed portion 69 of both seal layers 30 in a 100 ° C. atmosphere is set to “Pa”, and the 130 ° C. atmosphere It is necessary to establish the following relational expression (1) (2) with the yarn strength of "Pb", more preferably the following relational expression (3).

20N/15mm≤Pa≤65N/15mm... (One)

Pb/Pa≤1/4 … (2)

Pb≤5N/15mm... (3)

For example, in the graph showing the relationship between the yarn strength and the ambient temperature in FIG. 4 , among the curves C1 to C6 representing the resin for the seal layer, the resin for the seal layer represented by the solid line is the resin for the seal layer as described above. The relational expression (1) (2) is satisfied, and the resin for sealing layer unique to the present invention, and the resin for sealing layer indicated by the broken line (C3 to C6) does not satisfy the above-mentioned relational expression (1) (2), and this It is a resin for thread layers that deviated from the gist of the invention.

Since the electrical storage device of the present embodiment includes the seal layer 30 that satisfies the above relational expressions (1) and (2), in the heat seal portion, while sufficiently maintaining sealing (sealing) properties at room temperature and low temperature, the withstand voltage is increased. When it rises and reaches a high temperature range, degassing at high temperature is performed efficiently due to a decrease in yarn strength, and inadequacy such as ignition due to a decrease in pressure and temperature can be prevented.

In particular, in the present embodiment, in addition to the yarn strength at a high temperature of about 130 ° C., the yarn strength at a slightly high temperature of about 100 ° C. is clearly set, so that the yarn layer 30, that is, The heat seal portion gradually becomes softer and is gradually opened and degassed smoothly, thereby reliably preventing unexpected sudden degassing and adverse effects such as bumps in the electrolyte solution.

Further, in this embodiment, by satisfying the relational expression (3) described above, the heat seal portion can be opened more reliably at a high temperature, and defects such as ignition can be more reliably prevented.

In the present embodiment, since the high melting point metal foil side layer 33 exists outside the seal layer 30 in the thermally fused layer 3, the seal layer ( 30), that is, it is opened at the desired heat seal position. For this reason, the degree of degassing can be accurately controlled, and also in this respect, occurrence of unexpected gas or the like can be prevented reliably.

In the electricity storage device of the present embodiment, since the seal layer 30 is composed of the first seal layer 31 and the second seal layer 32 having different melting points, when the seal layer 30 is only the first seal layer 31 24 μm or more, and also in the case of the first seal layer 31 and the second seal layer 32, the resin pool can be formed large because the seal layer 30 is set to be 24 μm or more and the seal layer 30 is thick. By forming this resin pool, the sealability (sealability) at room temperature can be further improved.

Further, in the electrical storage device of the present embodiment, since the sealing layers 30 of the heat seal part diffuse and adhere tightly to each other, the resin is gradually softened by the modifier when the inside of the battery reaches a temperature of around 100° C., thereby preventing cohesive failure. It becomes easy. Since the heat seal part undergoes cohesive failure (cohesive peeling) at a high temperature in this way, the release position of gas can be reliably controlled in the heat seal part, and rapid release of gas can be avoided even more reliably.

Further, in the packaging material 1 of the present embodiment, when a lubricant is added to the inner surface side of the heat-sealing layer 3, the activity with respect to molding jigs such as molding molds can be further improved, and stable good quality can be achieved. Formability can be obtained more reliably.

Further, in the power storage device of the present embodiment, since there is no need to separately provide other parts such as a pressure release valve for degassing at high temperatures, the number of parts can be reduced and productivity can be improved accordingly.

In the above embodiment, the exterior case 65 is constituted by the tray member 64 obtained by molding the exterior material 1 and the flat lid member 60, but in the present invention, in particular, such a combination It is not limited and, for example, the configuration may be sufficient as the exterior case 65 made of a pair of planar (sheet-like) exterior materials 1, or a pair of tray members 64 are stacked facing each other. A phosphorus composition may be sufficient.

[Example]

[Table 1]

[Table 2]

[Table 3]

1. Production of film for heat-sealing layer

<Example 1>

As shown in Tables 1 to 3, the seal layer (first seal layer) and the film for the metal foil side layer disposed on the outer surface side are co-extruded using a T-die so that the film for the seal layer (first seal layer) is laminated in two layers. A film for heat sealing layer (sealant layer) having a thickness of 30 μm in which a metal foil side layer was laminated thereon was obtained.

In this laminated film, the first real layer is a propylene-ethylene random copolymer (rPP: melting point 125 ° C.), 30 wt% of the total amount of linear low-density polyethylene (m-LLDPE: melting point 108 ° C.) produced with a metallocene catalyst A film for sealing layer having a thickness of 24 μm and containing 1000 ppm of erucic acid amide (lubricant) and 2000 ppm of silica particles (antiblocking agent: AB agent) was used.

In addition, the metal foil side layer is an ethylene-propylene random copolymer (melting point 142 ° C.), polyolefin elastomer (melting point 142 ° C.) is added so as to be 20 wt% of the total amount, and 1000 ppm of erucic acid amide (lubricant) and A film for a metal foil side layer having a thickness of 6 μm and containing 2000 ppm of silica particles (antiblocking agent) was used.

In addition, in this Example 1, since the real layer is composed of only the first real layer not including the second real layer, it can be understood that the first real layer constitutes the entire real layer (Examples 2 to 9 and Comparative Examples 2 to 4 below). same as).

<Examples 2 to 9>

Using the film for seal layer (first seal layer) and the film for metal foil side layer of the components shown in Tables 1 to 3, similarly to the above Example 1, films for heat-sealing layers of Examples 2 to 9 having a two-layer structure were produced. did.

In addition, a lubricant and an antiblocking agent are contained in the same way as in Example 1 (also in Comparative Examples 2 to 4).

<Example 10>

As shown in Tables 1 to 3, the film for the first sealing layer, the film for the second sealing layer disposed on the outer surface side, and the film for the metal foil side layer disposed on the outer surface side of the film for the second sealing layer were laminated in three layers. A film for a thermally fused layer was obtained by co-extrusion as in Example 1 as much as possible.

In this laminated film, the film for the first seal layer is the same as in Example 1 except that the thickness is 6 µm. Further, as the film for the second sealing layer, rPP with a melting point of 125°C and a thickness of 18 µm was used without adding a modifier and containing 1000 ppm of erucic acid amide (lubricant). The film for the metal foil side layer was the same as in Example 1.

The sealing layer in the heat-sealing layer of this Example 10 is composed of two layers, a first sealing layer and a second sealing layer, and thereby the entire heat-sealing layer has a three-layer structure (Examples 11 to 11 below). 24, the same for Comparative Example 1).

<Examples 11 to 24>

Using the film for the first sealing layer, the film for the second sealing layer, and the film for the metal foil side layer of the components shown in Tables 1 to 3, the same as in Example 10, for the heat-sealing layer of Examples 11 to 24 having a three-layer structure. made the film.

In addition, a lubricant and an antiblocking agent are contained in the same way as in Example 10 (also in Comparative Example 1).

<Comparative example 1>

Using the film for the first seal layer, the film for the second seal layer, and the film for the metal foil side layer of the components shown in Tables 1 to 3, the film for the heat-sealing layer of Comparative Example 1 having a three-layer structure was prepared in the same manner as in Example 10. made

<Comparative Examples 2 to 4>

Using the film for seal layer (first seal layer) and the film for metal foil side layer of the components shown in Tables 1 to 3, similarly to Example 1, films for heat-sealed layers of Comparative Examples 2 to 4 having a two-layer structure were produced. did.

2. Fabrication of exterior materials for electrical storage devices

A chemical conversion solution composed of polyacrylic acid, a trivalent chromium compound, water, and alcohol is applied to both sides of an aluminum foil (A8079) having a thickness of 35 μm as the metal foil layer 4, and dried at 150° C. An aluminum foil on which a chemical conversion film was formed was prepared. The chromium adhesion amount by this chemical conversion film was 5 mg/m 2 on one side.

Next, a biaxially oriented 6-nylon (ONy) film having a thickness of 25 μm was dry-laminated as a substrate layer through a two-component curing type urethane-based adhesive on one surface (outer surface) of the chemically treated aluminum foil (metal foil layer). (Coupled).

Next, the outer surface of the metal foil side layer of the film for heat sealing layer prepared in the above Examples and Comparative Examples is passed through a two-component curing type maleic acid-modified polypropylene adhesive, and the other surface (inner surface) of the aluminum foil (metal foil layer) after dry lamination. , dry laminated by sandwiching between a rubber nip roll and a laminate roll heated to 100°C and pressing, and then aging (heating) at 40°C for 10 days, Examples 1 to 3 24 and comparative examples 1 to 4 were obtained.

[Table 4]

3. Evaluation test for each exterior material

<Normal temperature yarn strength>

At room temperature (25°C), after cutting out two test pieces each having a width of 15 mm x a length of 150 mm from the packaging material of each Example and each Comparative Example, the inner sealant layers of these two test pieces are in contact with each other. Using a heat seal device (TP-701-A) manufactured by Tester Sangyo Co., Ltd., under the conditions of a heat seal temperature: 180 ° C., seal pressure: 0.3 MPa (gauge display pressure), and real time: 4 seconds. Heat sealing was performed by single-sided heating, and a sealed exterior material (test body) for room temperature test in which inner thermal fusion layers were heat sealed was produced.

Next, with respect to the sealed exterior material (test specimen) for the room temperature test, in accordance with JIS Z0238-1998, using a strograph (AGS-5kNX) manufactured by Shimadzu Access, the exterior material (test specimen) was heat-sealed on the inside of the heat seal portion The peel strength when the layers (sealant layers) were peeled in a T shape at a tensile speed of 100 mm/min was measured, and this was taken as room temperature yarn strength (N/15 mm width). The results are shown in Table 4.

<High temperature (100°C and 130°C) yarn strength>

In the same manner as above, test specimens were crystallized from the packaging materials of each Example and Comparative Example, heat-sealed, and a sealed packaging material (test sample) for a 100 ° C. test and a sealed packaging material (test sample) for a 130 ° C. test were produced, respectively. .

Next, each test body was left still in an environment of 100 ° C. and 130 ° C. for 24 hours, and in the same environment as above, peeling at 100 ° C. and 130 ° C. The strength was measured, and this was taken as the high temperature (100°C and 130°C) yarn strength (N/15 mm width). The results are shown in Table 4.

"Pa" in "strength ratio (Pb/Pa)" in Table 4 is the yarn strength in a 100°C atmosphere, and "Pb" is the yarn strength in a 130°C atmosphere.

<Determination of Peeling State>

The state of peeling in the packaging material of each Example and Comparative Example was determined based on visual observation and observation of the layer at the beginning of peeling by cross-sectional SEM. The results are shown in Table 4.

<Melting point of resin (real layer)>

For each test body cut out from the packaging material of each Example and Comparative Example, the melting point of the real layer was measured using differential scanning calorimetry (DSC) based on JIS K7121. The results are shown in Table 3.

<Unboxing test>

A test body having a width of 100 mm × a length of 200 mm is cut out from the packaging material of each Example and Comparative Example, and folded at the center in the longitudinal direction so that the heat-sealing layers face each other. ), heat seal temperature: 180 ° C, yarn pressure: 0.3 MPa (gauge display pressure), yarn time: 4 seconds, yarn width 5 mm, on the two sides in contact with the folded portion by heating on one side. Heat sealing was performed to prepare a bag-shaped test body (exterior material) in which one side facing the folded portion was opened.

After pouring 2.0 g of water into this bag-shaped test body, the opening was sealed under the above yarn conditions and was used as a sealed sample.

Each bag sample was transferred into an oven, heated from 25 ° C. to 130 ° C. at a heating rate of 5 ° C./min, and held for 30 minutes after reaching 130 ° C., and the state of the bag sample was observed. Based on the observation, openability was evaluated according to the following criteria. The results are shown in Table 4.

A: It was opened while the temperature was rising to 100°C to 130°C, and the gas was released slowly.

B: Gas did not escape during the temperature rise to 130°C, but gas escaped gradually while maintaining the temperature at 130°C.

C: Opened while the temperature was rising to 100°C to 130°C, and the gas rapidly escaped.

X: It was not opened even in the maintenance of 130 degreeC.

Y: Opened during temperature rise to 100°C.

<general review>

As shown in Table 4, excellent evaluation was obtained in the opening test for the exterior packaging materials of Examples related to the present invention. On the other hand, the packaging materials of comparative examples that deviated from the gist of the present invention were inferior to the evaluation of the opening test.

This application claims the priority of Japanese Patent Application No. 2021-188342 filed on November 19, 2021 and Japanese Patent Application No. 2022-169864 filed on October 24, 2022, the disclosure content of which , constitutes a part of the present application as it is.

The terms and expressions used herein are used for purposes of description and not to be construed as limiting, and are not intended to exclude any equivalents of the features appearing and stated herein, but within the claimed scope of the present invention. It must be recognized that transformation is also permissible.

The exterior material for an electrical storage device of the present invention is a storage device such as a battery or capacitor used for mobile devices such as smartphones and tablets, a battery or capacitor used for power storage of hybrid vehicles, electric vehicles, wind power generation, photovoltaic power generation, and nighttime electricity. It can be used suitably at the time of manufacture.

1: exterior material
2: base layer
3: heat sealing layer
30: real floor
31: first real floor
32: second real floor
33: metal foil side layer
4: metal foil layer
6: power storage device
61: device body part
65: external case
69: heat seal part

Claims (9)

A metal foil layer, a base material layer made of resin provided on the outer surface side of the metal foil layer, and a heat-sealed resin layer provided on the inner surface side of the metal foil layer, wherein the heat-sealed layer is disposed on the innermost surface As an exterior material for an electrical storage device comprising a real layer,
In a state where the yarn layers are heat-sealed, the yarn strength in the heat-sealed portion of the yarn layers in a 100 ° C. atmosphere is set to “Pa”, and the yarn strength in a 130 ° C. atmosphere is set to “Pb”,
20N/15mm≤Pa≤65N/15mm
of Pb/Pa≤1/4
A packaging material for an electrical storage device characterized in that it is configured so that a relationship is established. According to claim 1,
The heat-sealing layer is provided on the outer surface side of the seal layer and includes a metal foil side layer having a melting point of 140° C. or higher. According to claim 1 or 2,
The packaging material for an electrical storage device characterized in that the seal layer includes a first seal layer and a second seal layer laminated on an outer surface side of the first seal layer and having a higher melting point than the first seal layer. According to claim 1 or 2,
An enclosure material for an electrical storage device characterized by being configured so that a relationship of Pb ≤ 5 N/15 mm is established. According to claim 1 or 2,
The seal layer is composed of a resin compound obtained by adding a polyolefin compound having a melting point 15° C. or more lower than that of rPP as a modifier to a propylene-ethylene random copolymer (rPP),
An exterior material for an electrical storage device, characterized in that the addition amount of the modifier is adjusted to 5 wt% to 50 wt% with respect to the resin compound. An external case for an electrical storage device for sealing an electrical storage device body portion to form an electrical storage device, comprising:
Equipped with the exterior material according to claim 1 or 2,
An exterior case for an electrical storage device characterized in that it is formed by heat-sealing the seal layers to each other. According to claim 6,
An exterior case for an electrical storage device characterized in that the heat-sealed portion of the sealing layers is cohesively separated from each other as the internal pressure rises. an electrical storage device main body;
Equipped with the exterior case according to claim 6,
The electrical storage device characterized in that the electrical storage device main body is sealed in the exterior case. an electrical storage device main body;
Equipped with the exterior material according to claim 1 or 2,
The electrical storage device according to claim 1, wherein the electrical storage device main body is covered with the exterior material.

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