JP7361487B2 - Exterior material for power storage devices and power storage devices - Google Patents

Description

The present invention is applicable to batteries and capacitors used in mobile devices such as smartphones, tablets, and digital cameras, as well as batteries and capacitors used in hybrid vehicles, electric vehicles, wind power generation, solar power generation, and nighttime electricity storage. The present invention relates to an exterior material for a device and an electricity storage device exteriorized with the exterior material.

Lithium ion secondary batteries are widely used as power sources for, for example, notebook computers, video cameras, mobile phones, and the like. This lithium ion secondary battery has a structure in which a battery main body (main body including a positive electrode, a negative electrode, and an electrolyte) is surrounded by an exterior material. As such an exterior material, for example, one having a structure in which an outer layer made of a stretched polyamide resin, a metal foil layer made of aluminum foil or the like, and an inner layer made of a heat-fusible resin are laminated in this order is known. (See Patent Document 1).

The battery is configured such that the battery main body is sandwiched between a pair of exterior materials and sealed by heat-sealing the peripheral edges of the inner layers of the pair of exterior materials. ing.

Japanese Patent Application Publication No. 2001-93482

By the way, if a device containing a battery (smartphone, tablet, etc.) is dropped or bumped into a shock, the bare cell will move within the exterior material surrounding the bare cell and hit the exterior material, causing damage to the battery. This causes wrinkles to occur in the exterior material, impairing its appearance, and there is also a risk that pinholes and the like may occur in the exterior material.

The present invention has been made in view of the above technical background, and provides an exterior material for a power storage device and a power storage device that enable a device main body covered with an exterior material to be fixed to the exterior material. The purpose is to

In order to achieve the above object, the present invention provides the following means.

[1] An exterior material for a power storage device including a metal foil layer and a heat-fusible resin layer as an inner layer,
An exterior packaging material for a power storage device, characterized in that a thermoadhesive resin layer is laminated on an inner surface of a heat-sealable resin layer in at least a part of the region of the exterior material that can be contacted with the electrical storage device main body.

[2] The electricity storage device according to item 1 above, wherein the thermoadhesive resin constituting the thermoadhesive resin layer is a two-component curable thermoadhesive resin containing a main resin and a block isocyanate as a curing agent. Exterior material for devices.

[3] The exterior packaging material for a power storage device according to item 2 above, wherein the blocking agent of the blocked isocyanate dissociates at 60°C to 100°C.

[4] The exterior material for a power storage device according to item 2 or 3, wherein the two-component curable thermally adhesive resin contains a dissociation catalyst.

[5] The exterior material for a power storage device according to any one of items 2 to 4 above, wherein the base material is an acid-modified polyolefin resin.

[6] The exterior material for an electricity storage device according to any one of items 1 to 5 above, wherein a base material layer is laminated on the outer surface of the metal foil layer.

[7] An exterior case for a power storage device comprising a molded body of the exterior material according to any one of items 1 to 6 above.

[8] A power storage device main body,
An exterior member consisting of the exterior material according to any one of the preceding clauses 1 to 6 and/or the exterior case according to the preceding clause 7,
An electricity storage device, wherein the electricity storage device main body is covered with the exterior member.

In the invention [1], since the heat-adhesive resin layer is laminated on the inner surface of the heat-adhesive resin layer in at least a part of the region of the exterior material that can be contacted with the main body of the power storage device, The adhesive resin layer allows the power storage device body to be bonded to the exterior material and fixed to the exterior material, so even if external pressure (vibration, impact, etc.) is applied to the power storage device, the power storage device body will remain intact. It does not move within the exterior material, making it difficult for wrinkles to occur in the exterior material, and also preventing liquid leakage. Furthermore, the main body of the power storage device can be fixed to the exterior material in a more stable state compared to fixing with double-sided tape.

In the invention [2], it is possible to improve the adhesive strength of the heat-adhesive resin layer, and also to improve the electrolyte resistance.

In the invention [3], the blocking group of the block isocyanate dissociates from the block isocyanate compound at 60°C to 100°C, and the thermoadhesive resin layer develops adhesiveness at a temperature lower than 60°C. This is advantageous because the heat-adhesive resin layer does not exhibit adhesive properties during the manufacturing process of the exterior material. In addition, since the heat-adhesive resin layer can be thermally bonded at a temperature of 100 degrees Celsius or less, the heat-adhesive resin layer will melt during this heat-adhesive process, preventing leakage of electrolyte, etc. Never happened. In addition, since thermal bonding is possible at a temperature of 100°C or lower, it can be used in a vacuum baking process (e.g. 80°C x 6 to 24 hours) before electrolyte injection, or in a degassing process (e.g. 60°C) after electrolyte injection. x 6 to 48 hours), the thermal adhesive resin layer can be thermally bonded at the same time.

In the invention [4], the reactivity of the heat-adhesive resin layer during heat bonding can be improved, and the adhesive strength can be improved.

In the invention [5], the electrolyte resistance of the heat-adhesive resin layer can be improved, the heat-adhesive resin layer is not easily deteriorated by the electrolyte, and sufficient adhesive strength can be maintained. Furthermore, the adhesion to the metal foil serving as the electrode can be further improved.

In the invention [6], since the base material layer is laminated on the outer surface of the metal foil layer, weather resistance can be improved and impacts such as external pressure can be alleviated.

In the invention [7], the power storage device main body can be bonded to the exterior material using the thermal adhesive resin layer, and the power storage device main body can be fixed to the exterior material, so that external pressure (vibration, shock, etc.) is not applied to the power storage device. The main body of the power storage device will not move within the exterior material even if the battery is applied, making it difficult for wrinkles to occur in the exterior material and preventing liquid leakage.

In the invention [8], the power storage device main body can be bonded to the exterior material using the thermal adhesive resin layer, and the power storage device main body can be fixed to the exterior material, so that external pressure (vibration, shock, etc.) is not applied to the power storage device. The main body of the power storage device will not move within the exterior material even if the battery is applied, making it difficult for wrinkles to occur in the exterior material and preventing liquid leakage.

FIG. 1 is a cross-sectional view showing an embodiment of an exterior material for a power storage device according to the present invention. 1 is a cross-sectional view showing an embodiment of a power storage device according to the present invention. FIG. 3 is a perspective view showing the exterior material (planar), the energy storage device main body, and the exterior case (three-dimensional molded body) that constitute the electricity storage device of FIG. 2 in a separated state before being heat-sealed. FIG. 2 is an explanatory diagram (perspective view showing a molded product for exterior packaging) of a method for creating a simulated battery. FIG. 3 is an explanatory diagram of a drop impact test method.

The exterior material 1 for a power storage device according to the present invention includes a heat-fusible resin layer 3 laminated on one surface of a metal foil layer 4 via a first adhesive layer (inner adhesive layer) 6, and further includes: A thermally adhesive resin layer 8 is laminated on the inner surface of the thermally adhesive resin layer 3 in at least a part of the area of the exterior material 1 that can be contacted with the power storage device main body 31 (see FIGS. 1 and 2). . According to this configuration, since the power storage device main body 31 can be bonded to the exterior material 1 using the thermal adhesive resin layer 8 and the power storage device main body 31 can be fixed to the exterior material 1, external pressure (vibration) can be applied to the power storage device 30. The power storage device main body 31 does not move within the exterior material 1 even when subjected to external shocks, shocks, etc.), thereby preventing the occurrence of wrinkles in the exterior material and liquid leakage.

Further, as shown in FIG. 1, a configuration may also be adopted in which a base material layer 2 is further laminated on the other surface of the metal layer 4 via a second adhesive layer (outer adhesive layer) 5. In this configuration, since the base material layer 2 is laminated on the other surface of the metal layer 4, sufficient insulation of the exterior material 1 can be ensured, and physical strength and impact resistance can also be ensured.

In the present invention, the base material layer (outer layer) 2 is formed of a heat-resistant resin layer. As the heat-resistant resin constituting the heat-resistant resin layer 2, a heat-resistant resin that does not melt at the heat-sealing temperature when heat-sealing the exterior material 1 is used. As the heat-resistant resin, it is preferable to use a heat-resistant resin having a melting point higher than the melting point of the heat-fusible resin constituting the heat-fusible resin layer 3 by 10° C. or more, and 20° C. or more higher than the melting point of the heat-fusible resin constituting the heat-fusible resin layer 3. It is particularly preferable to use a heat-resistant resin having a melting point higher than .degree. C. or higher.

The heat-resistant resin layer (outer layer) 2 is a member that mainly plays the role of ensuring good moldability as the exterior material 1, that is, it plays the main role of preventing breakage due to necking of the aluminum foil during molding. It is something.

The heat-resistant resin layer (outer layer) 2 is not particularly limited, and examples thereof include stretched polyamide films such as stretched nylon films, stretched polyester films, and the like. Among these, the heat-resistant resin layer 2 may be a biaxially oriented polyamide film such as a biaxially oriented nylon film, a biaxially oriented polybutylene terephthalate (PBT) film, a biaxially oriented polyethylene terephthalate (PET) film, or a biaxially oriented polyethylene terephthalate (PET) film. It is particularly preferable to use a phthalate (PEN) film having a hot water shrinkage rate of 1.5% to 12%. Moreover, as the heat-resistant resin layer 2, it is preferable to use a heat-resistant resin biaxially stretched film stretched by a simultaneous biaxial stretching method. The nylon is not particularly limited, and examples thereof include nylon 6, nylon 6,6, MXD nylon, and the like. The heat-resistant resin film layer 2 may be formed of a single layer (single stretched film), or may be formed of a multilayer consisting of a stretched polyester film/stretched polyamide film (stretched PET film/stretched nylon film). It may be formed of a multi-layer film, etc.).

The thickness of the heat-resistant resin layer 2 is preferably 5 μm to 50 μm. By setting the value above the preferable lower limit value, sufficient strength can be ensured as an exterior material, and by setting it below the preferable upper limit value, the stress during stretch forming and drawing forming can be reduced, improving formability. I can do it.

The heat-resistant resin layer 2 may be formed of a resin film, or may be a resin coat layer formed by applying a resin. The resin forming the resin coat layer is not particularly limited, and examples thereof include urethane resin, acrylic resin, and epoxy resin.

The second adhesive layer is not particularly limited, but includes, for example, a two-part curable adhesive (urethane adhesive, etc.), a photocurable adhesive, and the like. The thickness of the second adhesive layer (outer adhesive layer) 5 is preferably 1 μm to 3 μm.

In the present invention, the metal foil layer 4 serves to provide the exterior material 1 with gas barrier properties that prevent oxygen and moisture from entering. Although the metal foil layer 4 is not particularly limited, examples thereof include aluminum foil, copper foil, SUS foil, nickel foil, titanium foil, etc., and aluminum foil is generally used. In addition, clad foil or metal plated foil may be used. The thickness of the metal foil layer 4 is preferably 20 μm to 100 μm. By having a diameter of 20 μm or more, it is possible to prevent pinholes from occurring during rolling when manufacturing metal foil, and by having a diameter of 100 μm or less, stress during forming such as stretch forming and drawing can be reduced, improving formability. be able to.

It is preferable that at least the inner surface (the surface on the inner adhesive layer 6 side) of the metal foil layer 4 is subjected to a chemical conversion treatment. By performing such a chemical conversion treatment, corrosion of the metal foil surface by contents (such as battery electrolyte) can be sufficiently prevented. For example, the metal foil is subjected to a chemical conversion treatment by performing the following treatment. That is, for example, on the surface of metal foil that has been subjected to degreasing treatment,
1) Phosphoric acid and
chromic acid and
an aqueous solution of a mixture containing at least one compound selected from the group consisting of metal salts of fluoride and non-metal salts of fluoride; 2) phosphoric acid;
At least one resin selected from the group consisting of acrylic resin, chitosan derivative resin, and phenolic resin,
3) an aqueous solution of a mixture containing at least one compound selected from the group consisting of chromic acid and chromium (III) salts; 3) phosphoric acid;
At least one resin selected from the group consisting of acrylic resin, chitosan derivative resin, and phenolic resin,
At least one compound selected from the group consisting of chromic acid and chromium (III) salts,
An aqueous solution of a mixture containing at least one compound selected from the group consisting of metal salts of fluoride and non-metallic salts of fluoride.After coating the aqueous solution of any one of the above 1) to 3), drying By doing so, chemical conversion treatment is performed.

The amount of chromium deposited (per one side) in the chemical conversion film is preferably 0.1 mg/m ² to 50 mg/m ² , particularly preferably 2 mg/m ² to 20 mg/m ² .

The heat-fusible resin layer (inner layer) 3 has excellent chemical resistance against highly corrosive electrolytes used in lithium ion secondary batteries, etc., and also has heat sealability on the exterior material. It is responsible for providing the following information.

The resin constituting the heat-fusible resin layer 3 is not particularly limited, but includes, for example, polyethylene, polypropylene, ionomer, ethylene ethyl acrylate (EEA), ethylene methyl acrylate (EAA), and ethylene methacrylate. Examples include acid methyl resin (EMMA), ethylene-vinyl acetate copolymer resin (EVA), maleic anhydride-modified polypropylene, maleic anhydride-modified polyethylene, and the like.

The thickness of the heat-fusible resin layer 3 is preferably set to 15 μm to 100 μm. By setting the thickness to 15 μm or more, sufficient heat sealing strength can be ensured, and by setting the thickness to 100 μm or less, it contributes to thinning and weight reduction. Among these, it is more preferable that the thickness of the heat-fusible resin layer 3 is set to 10 μm to 80 μm. The heat-fusible resin layer 3 is preferably formed of a heat-fusible resin unstretched film layer, and the heat-fusible resin layer 3 may be a single layer or a multilayer. It's okay.

The first adhesive layer 6 is not particularly limited, and examples thereof include a thermosetting acrylic adhesive, a thermosetting acid-modified polypropylene adhesive, a thermosetting polyurethane adhesive, and the like. The thickness of the first adhesive layer (inner adhesive layer) 6 is preferably 1 μm to 5 μm.

In the present invention, the heat-adhesive resin layer 8 is a resin that develops adhesive properties when heated, and the heating temperature at which the adhesive property develops is lower than the melting point of the heat-fusible resin layer 3. desirable.

The heat-adhesive resin constituting the heat-adhesive resin layer 8 is not particularly limited, but may include a two-component curable heat-adhesive resin containing a main resin and a block isocyanate as a curing agent. It is preferable to use For example, by applying a liquid containing a main agent, a block isocyanate, a dissociation catalyst, and a solvent to the surface of the heat-fusible resin layer 3 by a method such as a gravure roll method and drying it, a heat-adhesive property can be obtained. A resin layer 8 is formed. The amount (solid content) of the heat-adhesive resin layer 8 is preferably set to 1 g/m ² to 10 g/m ² .

The main agent is not particularly limited, but includes, for example, carboxylic acid-modified olefin resins, carboxylic anhydride-modified olefin resins, polyols (trimethylolpropane, methylpentadiol, etc.).

The blocked isocyanate is a compound that stabilizes the isocyanate group by masking the highly reactive isocyanate group with a blocking agent, and when the blocking agent dissociates and the isocyanate group is regenerated by heat treatment. , exhibits high reactivity towards compounds containing active hydrogen and the like.

The blocked isocyanate is not particularly limited, but includes, for example, a compound in which the terminal isocyanate group of an isocyanate compound is masked with a blocking agent. Examples of the isocyanate compound include organic diisocyanates, polymeric type polyisocyanates, isocyanate group-terminated polymers obtained by reacting organic diisocyanates with active hydrogen group-containing compounds, modified isocyanurates, and the like.

The blocking agent is not particularly limited, but includes, for example, N,N'-diphenylformamidine (DPFE), phenol, cresol, ethylphenol, 2-hydroxypyridine, dimethyl malonate, urea, Examples include mixtures in which blocking agents such as formaldoxime and carbazole are added to adjust the dissociation temperature. By adjusting the dissociation temperature using these, it is possible to set the dissociation temperature of the blocking agent to 60°C to 100°C.

It is preferable to add the dissociation catalyst, which can improve the reactivity of the heat-adhesive resin layer. The dissociation catalyst is not particularly limited, but includes, for example, dioctyltin dilaurate, dibutyltin dilaurate, and the like.

The solvent is not particularly limited, and examples thereof include toluene, methylcyclohexane, and the like.

Additives such as an antiblocking agent, wax, and a slip agent (lubricant) may be added to the thermoadhesive resin.

The thermal adhesive resin layer 8 is preferably formed over the entire region of the exterior material that can be contacted with the power storage device main body 31, but is not particularly limited to this form. It may be a part of the area that can come into contact with the portion 31. Further, it is preferable that the thermal adhesive resin layer 8 is not formed on the peripheral portion to be sealed (peripheral portion for sealing) where sealing and bonding by heat sealing is performed.

By molding (deep drawing, stretch molding, etc.) the exterior material 1 for a power storage device of the present invention, an exterior case (battery case, etc.) 14 can be obtained (see FIGS. 2 and 3). In addition, the exterior material 1 of the present invention can also be used as it is without being subjected to molding (see FIGS. 2 and 3).

FIG. 2 shows an embodiment of a power storage device 30 configured using the power storage device exterior material 1 of FIG. 1. This power storage device 30 is a lithium ion secondary battery. In this embodiment, as shown in FIGS. 2 and 3, an exterior member 15 is constituted by an exterior case 14 obtained by molding the exterior material 1 and the planar exterior material 1. Thus, a substantially rectangular parallelepiped-shaped power storage device main body (electrochemical element, etc.) is placed on the thermally adhesive resin layer 8 on the bottom of the housing recess of the exterior case 14 obtained by molding the exterior case 1 of the present invention. 31 is disposed, and the exterior material 1 of the present invention is disposed on the electricity storage device main body 31 with its heat adhesive resin layer 8 side facing inward (lower side) without being molded, and the planar The peripheral edge of the heat-fusible resin layer 3 of the exterior material 1 and the heat-fusible resin layer 3 of the flange portion (sealing peripheral edge) 29 of the exterior case 14 are sealed by heat sealing. By doing so, the power storage device 30 of the present invention is configured (see FIGS. 2 and 3). The inner surface of the bottom wall of the housing recess of the exterior case 14 is a thermoadhesive resin layer 8, and the outer surface of the housing recess is a base material layer (outer layer) 2 (see FIG. 3). ). After forming the power storage device 30, heating is performed to dissociate the blocking agent of the block isocyanate in the heat adhesive resin layer 8, and the isocyanate group is regenerated, causing a reaction and causing the heat adhesive resin layer 8 to store electricity. It is adhered to the device main body part 31. In this electricity storage device 30, the electricity storage device main body 31 can be bonded to the exterior member 15 using the thermal adhesive resin layer 8, and the electricity storage device main body 31 can be fixed to the exterior member 15. The power storage device main body 31 does not move within the exterior member 15 even if a power storage device main body 31 is subjected to abrasion (shock, impact, etc.), and wrinkles in the exterior member 15 caused by rubbing of the power storage device main body 31 can be prevented.

In FIG. 2, reference numeral 39 denotes a heat-sealed portion in which the peripheral edge of the exterior material 1 and the flange portion (sealing peripheral edge) 29 of the exterior case 14 are joined (welded). Further, in FIG. 3, 8A indicates a coating area of a heat-adhesive resin layer provided on the lower surface side of the planar exterior material 1. Note that in the power storage device 30, the tip of the tab lead connected to the power storage device main body 31 is led out to the outside of the exterior member 15, but is not shown.

The power storage device main body 31 is not particularly limited, and examples thereof include a battery main body, a capacitor main body, a capacitor main body, and the like.

In the above embodiment, the exterior member 15 was configured to include the exterior case 14 obtained by molding the exterior material 1 and the planar exterior material 1 (see FIGS. 2 and 3). The combination is not particularly limited to such a combination, and for example, the exterior member 15 may be composed of a pair of planar exterior materials 1, or may be composed of a pair of exterior cases 14. It's okay.

Next, specific examples of the present invention will be described, but the present invention is not particularly limited to these examples.

<Example 1>
A chemical conversion treatment solution consisting of phosphoric acid, polyacrylic acid (acrylic resin), chromium (III) salt compound, water, and alcohol was applied to both sides of aluminum foil 4 with a thickness of 35 μm, and then dried at 180°C. , a chemical conversion film was formed. The amount of chromium deposited on this chemical conversion film was 10 mg/m ² per side.

Next, a biaxially stretched nylon film (outer layer) 2 with a thickness of 15 μm is dried on one side of the chemical conversion treated aluminum foil 4 via a two-component curing type urethane adhesive (thickness 2 μm) 5. Laminated (pasted together).

Next, a 30 μm thick unstretched polypropylene film (inner layer) 3 is bonded to the other surface of the dry laminated aluminum foil 4 via a two-component curing olefin adhesive (2 μm thick) 6. After that, it was sandwiched between a rubber nip roll and a laminating roll heated to 100° C. and crimped.

20 parts by mass of maleic anhydride-modified polypropylene resin, 5 parts by mass of blocked isocyanate, and Elca A heat blend of 0.1 parts by mass of acid amide (lubricant), 0.4 parts by mass of polyethylene wax (wax), 0.5 parts by mass of silica (antiblocking agent), 40 parts by mass of toluene, and 34 parts by mass of methylcyclohexane. After applying adhesive resin at 3 g/m ² , it was dried.

After confirming that the surface coated with the heat-adhesive resin had no tackiness, a heat aging treatment was performed for 10 days in an environment of 40° C., thereby obtaining the exterior material 1 for a power storage device shown in FIG. 1.

The contents of the above block isocyanate are:
・Adduct of hexamethylene diisocyanate and 1,3-butanediol ・Blocking agent: diphenylformamidine (DPFA)
・Dissociation catalyst: dibutyltin dilaurate ・Solvent: butyl acetate.

<Example 2>
Exterior material 1 for a power storage device shown in FIG. 1 was obtained in the same manner as in Example 1 except that the block isocyanate shown below was used as the block isocyanate.

That is, the contents of the block isocyanate used in Example 2 are:
・Adduct of hexamethylene diisocyanate and 1,3-butanediol ・Blocking agent: diphenylformamidine (DPFA)
-Solvent: Butyl acetate.

<Example 3>
Exterior material 1 for a power storage device shown in FIG. 1 was obtained in the same manner as in Example 1, except that 20 parts by mass of trimethylolpropane was used instead of 20 parts by mass of maleic anhydride-modified polypropylene resin.

<Example 4>
Exterior material 1 for a power storage device shown in FIG. 1 was obtained in the same manner as in Example 1 except that the block isocyanate shown below was used as the block isocyanate.

That is, the contents of the block isocyanate used in Example 4 are:
- Adduct of hexamethylene diisocyanate and 1,3-butanediol - Blocking agent: dimethylpyrazole - Dissociation catalyst: dibutyltin dilaurate - Solvent: butyl acetate.

<Example 5>
Exterior material 1 for a power storage device shown in FIG. 1 was obtained in the same manner as in Example 1 except that the block isocyanate shown below was used as the block isocyanate.

That is, the contents of the block isocyanate used in Example 5 are:
・Adduct of hexamethylene diisocyanate and 1,3-butanediol ・Blocking agent: Methyl ethyl ketoxime (MEKO)
・Dissociation catalyst: dibutyltin dilaurate ・Solvent: butyl acetate.

<Comparative example 1>
An exterior material for a power storage device was obtained in the same manner as in Example 1, except that no thermal adhesive resin was applied.

Each of the exterior materials for power storage devices obtained as described above was evaluated by the following evaluation methods.

<Creating a simulated battery>
A molding base piece (80 mm x 160 mm) is cut out from the exterior material for each power storage device, and this molding base piece is molded using a deep drawing mold and a trimming mold to form a piece of 40 mm wide x 120 mm long. A molded product for exterior use (molding recess: short side 30 mm x long side 55 mm x depth 4 mm) was obtained (see FIG. 4). A thermoadhesive resin layer 8 is formed on the upper surface of the planar part (the right half in FIG. 4) of this exterior molded product, and a thermoadhesive resin layer 8 is also formed on the upper surface of the bottom wall of the molded recess. (See Figure 4). Next, a simulated bare cell (width 29 mm x length 50 mm x thickness 4 mm) made by covering the surface of a polyethylene resin block with aluminum foil having a thickness of 20 μm is housed in the molding recess, and then the exterior molded product is After overlapping the planar part on the upper surface of the molded recess by valley-folding it at the center position in the length direction, the overlapping peripheral flange parts (width 5 mm) on three sides were heated and heat-sealed (thermal melting). The adhesive resin layers 3 were fused and sealed). Next, the blocking agent of the block isocyanate is dissociated by heat aging treatment in an environment of 60°C to 100°C for 8 hours, and the heat-adhesive resin layer of the exterior material is adhered to the simulated bare cell. Obtained 30A.

<Method for measuring curing temperature of thermal adhesive resin>
The thermoadhesive resin used in Example 1 was applied onto a glass substrate, and the coating film was cured by heating at a predetermined temperature for 30 minutes. After soaking for 24 hours, the following gel fraction was calculated,
Gel fraction (%) = {(mass of part not dissolved in mixed solvent)/(mass of coating film before immersion in mixed solvent)} x 100
The temperature at which the gel fraction became 80% or more was defined as the curing temperature (° C.). Similar measurements were conducted for the thermoadhesive resins of Examples 2 to 5 to determine the curing temperature (° C.).

<Drop impact test method>
A drop impact test was conducted in accordance with JIS C60068-2-31:2013 Environmental Test Methods - Electricity/Electronics - Part 2-31: Drop test and fall test method (test symbol: Ec). The simulated battery 30A was fixed on one side of a PC board (polycarbonate board) 60 with a size of 60 mm x 120 mm with double-sided adhesive tape to obtain a test piece (see Figure 5), and this test piece was subjected to the Annex B "Gravity drop test". In accordance with the Severity Selection Guidelines, the drop height was set to 1 m, and the test piece was allowed to fall naturally so that the corner part collided with the concrete floor surface (see Figure 5). After performing a drop test once on each of the four corners, the appearance of the exterior material of the simulated battery was observed and evaluated based on the following criteria.
(Judgment criteria)
“◎”…There are no wrinkles on the exterior material (passed)
“○”…There are slight wrinkles on the corners of the exterior material, but it is at a level that does not pose a problem (passed)
“×”: Significant wrinkles occurred at the corners of the exterior material.

As is clear from Table 1, the electricity storage devices constructed using the exterior materials for energy storage devices of Examples 1 to 5 according to the present invention have a simulated bare cell that is adhesively fixed to the exterior material, so it is easy to avoid dropping. Even when subjected to impact, the appearance of wrinkles in the exterior material was suppressed.

On the other hand, in Comparative Example 1 in which the heat-adhesive resin layer was not provided on the exterior material, the simulated bare cell was not fixed to the exterior material, so that the exterior material was noticeably wrinkled.

As a specific example, the exterior material for a power storage device according to the present invention includes, for example,
・Used as an exterior material for various power storage devices such as lithium secondary batteries (lithium ion batteries, lithium polymer batteries, etc.), lithium ion capacitors, electric double layer capacitors, etc. Moreover, the electricity storage device according to the present invention includes an all-solid-state battery in addition to the electricity storage device exemplified above.

1...Exterior material for power storage device 2...Base material layer (outer layer)
3... Heat-fusible resin layer (inner layer)
4...Metal foil layer 8...Thermoadhesive resin layer 15...Exterior member 30...Electricity storage device 31...Energy storage device main body

Claims (7)

An exterior material for a power storage device comprising a metal foil layer and a heat-fusible resin layer as an inner layer,
A heat-adhesive resin layer is laminated on the inner surface of the heat-adhesive resin layer in at least a part of the region of the exterior material that can be contacted with the power storage device main body,
The thermal adhesive resin constituting the thermal adhesive resin layer is a two-part curable thermal adhesive resin containing a main resin and a block isocyanate as a curing agent,
The heat-adhesive resin constituting the heat-adhesive resin layer is a resin that develops adhesive properties when heated, and the heating temperature at which the adhesive property develops is lower than the melting point of the heat-fusible resin layer. An exterior material for power storage devices featuring: The exterior packaging material for a power storage device according to claim 1 , wherein the blocking agent of the blocked isocyanate dissociates at 60°C to 100°C. The exterior material for a power storage device according to claim 1 or 2, wherein the two-component curable thermoadhesive resin contains a dissociation catalyst. The exterior material for a power storage device according to any one of claims 1 to 3, wherein the base material is an acid-modified polyolefin resin. The exterior material for a power storage device according to any one of claims 1 to 4, wherein a base material layer is laminated on the outer surface of the metal foil layer. An exterior case for a power storage device comprising a molded body of the exterior material according to any one of claims 1 to 5. A power storage device main body,
An exterior member comprising the exterior material according to any one of claims 1 to 5 and/or the exterior case according to claim 6,
An electricity storage device, wherein the electricity storage device main body is covered with the exterior member.

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