JP2019139832A - Jacket material for power storage device and power storage device - Google Patents

Abstract

To provide a jacket material for a power storage device capable of inhibiting adhesion of polyamide resin of the outer layer of the jacket material while heat sealing, and thereby capable of improving productivity.SOLUTION: A jacket material for a power storage device includes a polyamide resin layer 2 as an outer layer, a heat-seal resin layer 3 as an inner layer, and a metal foil layer 4 placed therebetween. Assuming the on-set temperature derived from a heat of melting distribution curve obtained by differential scanning calorimetry of the polyamide resin is (Y) (°C), and the fusion point of the polyamide resin derived from the heat of melting distribution curve is (X) (°C), the polyamide resin satisfies rational expressions X-Y≤3.0 and X≥218.SELECTED DRAWING: Figure 1

Description

  The present invention is for batteries and capacitors used for portable devices such as smartphones and tablets, hybrid vehicles, electric vehicles, wind power generation, solar power generation, storage devices such as batteries and capacitors used for storage of night electricity. The present invention relates to an exterior material and an electricity storage device that is exteriorized with the exterior material.

  In the present specification and claims, the “melting heat distribution curve” refers to the temperature measured at the first temperature rise (first run) using an input compensation DSC (differential scanning calorimeter). It means the melting heat distribution curve (thermogram) with the axis and the heat flow as the vertical axis.

  In the present specification and claims, the “onset temperature” corresponds to the intersection of the tangent line at the maximum gradient point (inflection point) of the melting heat distribution curve and the extension line of the base line (baseline). It means the temperature to do.

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

  And a battery is sealed and comprised by a battery main-body part being pinched | interposed by a pair of exterior materials, and the peripheral part of the inner side layer of the pair of exterior materials being heat-seal-bonded (heat-sealed). ing. By sufficiently sealing with such heat seal bonding, leakage of the electrolyte can be prevented.

JP 2001-93482 A (Claims 1, 3 etc.)

  By the way, the polyamide resin that constitutes the outermost layer with the exterior material having the above-described structure can have a deeper molding depth when deep-drawn and has excellent puncture resistance, while having a melting point. There is a problem that productivity is poor because a poor sealing occurs such that the polyamide resin layer (outermost layer) adheres to the seal bar when heat sealing is performed at a high temperature of 200 ° C. or higher.

  In order to prevent the occurrence of such a sealing failure, a configuration in which a polyester resin layer is further laminated on the outer surface of the polyamide resin layer has been studied. However, there is a problem in that the cost increases and the moldability decreases.

  In addition, fluororesin coating is applied to the surface of the seal bar to prevent it from adhering to the seal bar, but the thermal conductivity is lowered by applying the fluororesin coating, and the cycle time of the heat sealing process is reduced. In addition to the increase, there is a problem that the heat seal temperature has to be set higher.

  The present invention has been made in view of such a technical background, and it is possible to prevent the polyamide resin of the outer layer of the exterior material from adhering to the seal bar when performing heat sealing, thereby improving productivity. It is an object of the present invention to provide an exterior material for an electricity storage device that can be produced and an electricity storage device that is sheathed with the exterior material.

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

[1] A power storage device exterior material including a polyamide resin layer as an outer layer, a heat-fusible resin layer as an inner layer, and a metal foil layer disposed between both layers,
In the polyamide resin, the onset temperature derived from the melting heat distribution curve obtained by differential scanning calorimetry of the polyamide resin is “Y” (° C.), and the melting point of the polyamide resin derived from the melting heat distribution curve is “X”. "(℃),
X−Y ≦ 3.0
And X ≧ 218
An exterior material for an electricity storage device, which is a polyamide resin satisfying the relational expression:

[2] An electricity storage device body,
An exterior member including the exterior material for an electricity storage device according to the preceding item 1,
The electricity storage device, wherein the electricity storage device body is covered with the exterior member.

  In the invention of [1], the outer layer satisfies the relational expressions of XY ≦ 3.0 (the difference between the melting point and the onset temperature is 3.0 ° C. or less) and X ≧ 218 (the melting point is 218 ° C. or more). Since the polyamide resin is used, it is possible to prevent the polyamide resin of the outer layer of the exterior material from adhering to the seal bar when heat-sealing the exterior material, thereby improving productivity.

  In the invention of [2], since it is packaged with an exterior member including the exterior material for an electrical storage device having the above-described configuration, an electrical storage device with excellent productivity is provided.

It is sectional drawing which shows one Embodiment of the exterior material for electrical storage devices which concerns on this invention. It is sectional drawing which shows one Embodiment of the electrical storage device which concerns on this invention. It is a perspective view shown in the separated state before heat-sealing the exterior material (planar thing) which comprises the electrical storage device of FIG. 2, the electrical storage device main-body part, and an exterior case (molded object shape | molded in the solid shape). It is a graph which shows the heat of fusion distribution curve measured by the first temperature rise using the input compensation type DSC about nylon P used in Example 1. This melting heat distribution curve shows that the melting point of nylon P is 220.5 ° C. and the onset temperature is 219.0 ° C. It is a graph which shows the heat of fusion distribution curve measured by the first temperature rise using the input compensation type DSC about nylon U used in the comparative example 3. From this heat of fusion distribution curve, it can be seen that nylon U has a melting point of 217.7 ° C. and an onset temperature of 214.0 ° C.

  One embodiment of an exterior material 1 for an electricity storage device according to the present invention is shown in FIG. The power storage device exterior material 1 is used for a lithium ion secondary battery case.

  The electricity storage device exterior material 1 includes a polyamide resin layer (outer layer) 2 laminated and integrated on one surface of a metal foil layer 4 via a first adhesive layer 5, and the other side of the metal foil layer 4. The heat-fusible resin layer (inner layer) 3 is laminated and integrated on the surface with a second adhesive layer 6 interposed therebetween.

  In the exterior device 1 for an electricity storage device according to the present invention, the polyamide resin layer (outer layer) 2 has an onset temperature derived from a melting heat distribution curve obtained by differential scanning calorimetry of the polyamide resin as “Y” (° C. ), And the melting point of the polyamide resin derived from the melting heat distribution curve is “X” (° C.), the polyamide resin satisfying the relational expressions of XY ≦ 3.0 and X ≧ 218. . Thus, the outer layer 2 is made of a polyamide resin that satisfies the relational expressions of XY ≦ 3.0 and X ≧ 218. It is possible to prevent the polyamide resin of the layer 2 from adhering to the seal bar and improve productivity.

  Especially, it is preferable that the said polyamide resin layer (outer layer) 2 is comprised with the polyamide resin which satisfy | fills the relational expression of XY <= 2.5 and X> = 218. In this case, it is possible to further prevent the polyamide resin of the outer layer 2 of the exterior material from adhering to the seal bar when heat-sealing the exterior material, thereby further improving productivity.

  The polyamide resin constituting the polyamide resin layer 2 may be a polyamide resin satisfying the relational expression of “XY ≦ 3.0 and X ≧ 218”. For example, 6 nylon satisfying the relational expression Examples include films, 6,6 nylon films, MXD nylon films, and the like. The polyamide resin layer 2 may be formed as a single layer or a multilayer.

  The thickness of the polyamide resin layer 2 is preferably 8 μm to 50 μm. By setting it above the above preferred lower limit value, it is possible to ensure sufficient strength as an exterior material, and by setting it below the above preferred upper limit value, it is possible to reduce the stress at the time of molding such as stretch forming, draw forming, etc. and improve moldability Can be made. Among them, the thickness of the polyamide resin layer 2 is particularly preferably 12 μm to 25 μm.

  The heat-fusible resin layer (inner layer) 3 has excellent chemical resistance against highly corrosive electrolytes used in lithium ion secondary batteries and the like, and heat sealability on the exterior material. It plays the role of granting.

  The heat-fusible resin layer 3 is not particularly limited, but is preferably a heat-fusible resin unstretched film layer. The heat-fusible resin layer unstretched film layer 3 is not particularly limited, but is at least one selected from the group consisting of polyethylene, polypropylene, olefin copolymers, acid-modified products thereof, and ionomers. It is preferable that the film is composed of an unstretched film made of a heat-fusible resin. The heat-fusible resin layer 3 may be a single layer or a multilayer.

  The thickness of the heat-fusible resin layer 3 is preferably set to 10 μm to 80 μm. When the thickness is 10 μm or more, pinholes can be sufficiently prevented from being generated, and by setting the thickness to 80 μm or less, the amount of resin used can be reduced and the cost can be reduced. In particular, the thickness of the heat-fusible resin layer 3 is particularly preferably set to 25 μm to 50 μm.

  A lubricant may be contained in the heat-fusible resin layer 3. The lubricant is not particularly limited, but a fatty acid amide is preferably used. The fatty acid amide is not particularly limited, and examples thereof include saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylol amides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid ester amides, and aromatic bisamides. Is mentioned.

  The metal foil layer 4 plays a role of imparting a gas barrier property to the exterior material 1 to prevent entry of oxygen and moisture. Although it does not specifically limit as said metal foil layer 4, For example, aluminum foil, SUS foil (stainless steel foil), iron foil, copper foil etc. are mentioned, Aluminum foil is generally used. The thickness of the metal foil layer 4 is preferably 5 μm to 50 μm. When it is 5 μm or more, it is possible to prevent the occurrence of pinholes during rolling when producing metal foil, and when it is 50 μm or less, it is possible to reduce the stress during forming such as stretch forming and draw forming, thereby improving formability. be able to. Especially, it is especially preferable that the thickness of the metal foil layer 4 is 10 μm to 30 μm.

The metal foil layer 4 is preferably subjected to a chemical conversion treatment on at least the inner surface (the surface on the second adhesive layer 6 side). By performing such a chemical conversion treatment, corrosion of the metal foil surface by the contents (battery electrolyte or the like) can be sufficiently prevented. For example, the metal foil is subjected to chemical conversion treatment by the following treatment. That is, for example, on the surface of the metal foil that has been degreased,
1) phosphoric acid;
Chromic acid,
An aqueous solution of a mixture comprising at least one compound selected from the group consisting of a metal salt of fluoride and a nonmetal salt of fluoride; 2) phosphoric acid;
At least one resin selected from the group consisting of acrylic resins, chitosan derivative resins and phenolic resins;
An aqueous solution of a mixture comprising at least one compound selected from the group consisting of chromic acid and a chromium (III) salt, 3) phosphoric acid,
At least one resin selected from the group consisting of acrylic resins, chitosan derivative resins and phenolic resins;
At least one compound selected from the group consisting of chromic acid and a chromium (III) salt;
An aqueous solution of a mixture comprising at least one compound selected from the group consisting of a fluoride metal salt and a fluoride non-metal salt. After applying an aqueous solution of any one of the above 1) to 3), drying is performed. Then, chemical conversion treatment is performed.

The conversion coating, chromium coating weight preferably is 0.1mg / m ² ~50mg / m ² as a (per one surface), in particular 2mg / m ² ~20mg / m 2 preferred.

  The first adhesive layer 5 is not particularly limited, and examples thereof include a polyurethane adhesive layer, a polyester polyurethane adhesive layer, and a polyether polyurethane adhesive layer. The thickness of the first adhesive layer 5 is preferably set to 1 μm to 5 μm. Especially, it is especially preferable that the thickness of the said 1st adhesive bond layer 5 is set to 1 micrometer-3 micrometers from a viewpoint of thickness reduction of an exterior material and weight reduction.

  Although it does not specifically limit as said 2nd adhesive bond layer 6, For example, what was illustrated as said 1st adhesive bond layer 5 can be used, However, The polyolefin-type adhesive agent with few swelling by electrolyte solution is used. Is preferred. The thickness of the second adhesive layer 6 is preferably set to 1 μm to 5 μm. Especially, it is especially preferable that the thickness of the said 2nd adhesive bond layer 6 is set to 1 micrometer-3 micrometers from a viewpoint of thickness reduction of an exterior material and weight reduction.

  An exterior case (battery case or the like) 10 can be obtained by molding (such as deep drawing or stretch molding) the exterior material 1 for an electricity storage device of the present invention (see FIG. 3). In addition, the exterior material 1 of this invention can also be used as it is, without using for shaping | molding (refer FIG. 3).

  One Embodiment of the electrical storage device 30 comprised using the exterior material 1 for electrical storage devices of this invention is shown in FIG. The electricity storage device 30 is a lithium ion secondary battery. In the present embodiment, as shown in FIGS. 2 and 3, an exterior member 15 is configured by an exterior case 10 obtained by molding the exterior material 1 and the planar exterior material 1. Accordingly, a power storage device main body 31 (electrochemical element or the like) 31 having a substantially rectangular parallelepiped shape is stored in the storage recess of the external case 10 obtained by molding the exterior material 1 of the present invention. The heat-sealable resin layer of the planar sheathing material 1 is disposed on the top of the heat-sealable resin layer 3 without being molded, with the heat-sealable resin layer 3 side facing inward (downward). 3 and the heat-fusible resin layer 3 of the flange part (sealing peripheral part) 29 of the outer case 10 are sealed and sealed by heat sealing, whereby the electricity storage device of the present invention 30 is configured (see FIGS. 2 and 3). The inner surface of the housing recess of the outer case 10 is a heat-fusible resin layer 3, and the outer surface of the housing recess is a base material layer (outer layer) 2 (see FIG. 3).

  In FIG. 2, reference numeral 39 denotes a heat seal part in which the peripheral part of the outer packaging material 1 and the flange part (sealing peripheral part) 29 of the outer case 10 are joined (welded). In the electricity storage device 30, the tip end portion of the tab lead connected to the electricity storage device main body 31 is led out 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, and a capacitor main body.

  The width of the heat seal part 39 is preferably set to 0.5 mm or more. Sealing can be reliably performed by setting it as 0.5 mm or more. Especially, it is preferable to set the width | variety of the said heat seal part 39 to 3 mm-15 mm.

  In the above embodiment, the exterior member 15 has a configuration including the exterior case 10 obtained by molding the exterior material 1 and the planar exterior material 1 (see FIGS. 2 and 3). It is not particularly limited to such a combination. 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 10. May be.

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

<Raw materials>
[Nylon P]: Nylon [Nylon Q]: DSC measurement with a melting point of 220.5 ° C. and an onset temperature of 219.0 ° C. determined from the melting heat distribution curve (see FIG. 4) obtained by DSC measurement The melting point determined from the melting heat distribution curve obtained from the DSC measurement is a nylon [nylon R] having a melting point of 221.7 ° C. and an onset temperature of 219.3 ° C. Is 219.5 ° C. and the onset temperature is 217.9 ° C. Nylon [Nylon S]... The melting point obtained from the melting heat distribution curve obtained by DSC measurement is 220.4 ° C., and the onset temperature is Nylon [Nylon T] at 216.1 ° C. The melting point determined from the melting heat distribution curve obtained by DSC measurement is 219.7 ° C., and the onset temperature is 214.5 ° C. Ron melting point obtained from the nylon U] ... DSC melting heat distribution curve obtained by the measurement (see FIG. 5) is 217.7 ° C., nylon onset temperature of 214.0 ° C..

<Measuring method of melting heat distribution curve etc. by differential scanning calorimetry (DSC)>
The melting heat distribution curve of the nylon P to U is as follows. Using an input compensation type DSC (differential scanning calorimeter), sample amount: 0.4 mg to 0.6 mg, under nitrogen atmosphere (nitrogen flow rate: 20 mL / min), Temperature increase rate: The melting heat distribution curve at the first temperature increase (30 ° C. to 280 ° C.) was measured under the condition of 10 ° C./min. Next, the melting point (° C.) and the onset temperature (° C.) were determined from the obtained heat of fusion distribution curve. As the input compensation type DSC, “input compensation type differential scanning calorimetry system DSC8000” manufactured by PerkinElmer Co., Ltd. was used.

<Example 1>
After applying a chemical conversion treatment solution composed of phosphoric acid, polyacrylic acid (acrylic resin), chromium (III) salt compound, water, and alcohol on both surfaces of the aluminum foil 4 having a thickness of 35 μm, drying is performed at 180 ° C. Then, a chemical conversion film was formed. The amount of chromium deposited on this chemical film was 10 mg / m ² per side.

  Next, the biaxially stretched nylon P film 2 having a thickness of 15 μm was dry-laminated (laminated) on one surface of the chemical conversion-treated aluminum foil 4 via a two-component curable urethane adhesive 5. Next, an unstretched polypropylene film (heat-fusible resin layer) 3 having a thickness of 30 μm is bonded to the other surface of the aluminum foil 4 with a maleic anhydride-modified polypropylene adhesive 6, and then 5 ° C. in an environment of 40 ° C. By leaving it for a day, the exterior | packing material 1 for electrical storage devices shown in FIG.

<Example 2>
Except that nylon Q was used in place of nylon P as the polyamide resin for the outer layer, an electricity storage device exterior material 1 having the configuration shown in FIG. 1 was obtained in the same manner as in Example 1.

<Example 3>
Except that nylon R was used in place of nylon P as the polyamide resin for the outer layer, an electricity storage device exterior material 1 having the configuration shown in FIG. 1 was obtained in the same manner as in Example 1.

<Comparative Example 1>
An exterior material for an electricity storage device was obtained in the same manner as in Example 1 except that nylon S was used instead of nylon P as the polyamide resin of the outer layer.

<Comparative example 2>
An exterior material for an electricity storage device was obtained in the same manner as in Example 1 except that nylon T was used in place of nylon P as the polyamide resin of the outer layer.

<Comparative Example 3>
An exterior material for an electricity storage device was obtained in the same manner as in Example 1 except that nylon U was used in place of nylon P as the polyamide resin of the outer layer.

  Each power storage device exterior material obtained as described above was evaluated based on the following evaluation method. The results are shown in Table 1.

<Evaluation method for adhesion to seal bar>
Prepare five samples of the obtained energy storage device exterior material cut into a rectangular shape with a length of 100 mm and a width of 50 mm. Each sample is folded inward at two equal positions in the length direction, and the peripheral portions of the inner layer are overlapped. In addition, this was sandwiched and heat-sealed by a pair of heat seal bars under the following sealing conditions of each temperature × 0.2 MPa × 3 seconds. The respective temperatures are 198 ° C., 200 ° C., 203 ° C., 205 ° C., and 210 ° C. Whether or not the outer layer of the exterior material adhered to the seal bar when the seal bar was separated was checked, and the adhesion prevention property was evaluated based on the following criteria.
(Criteria)
“◯”: The outer layer of the outer packaging material does not adhere to the seal bar at all. “△”… Although the outer layer of the outer packaging material once adheres, the outer layer of the outer packaging material is separated from the seal bar due to the weight of the outer packaging material. Adhere to the seal bar.

  As is apparent from Table 1, the outer packaging materials for the electricity storage devices of Examples 1 to 3 of the present invention do not adhere to the seal bar at all even when heat sealing is performed at a temperature of 205 ° C. It is possible to improve the productivity of the heat sealing process without causing defects.

  On the other hand, the outer packaging material for power storage devices of Comparative Examples 1 to 3 caused the outer layer of the packaging material to adhere to the seal bar when heat-sealed at a temperature of 205 ° C. (productivity was low). Not good).

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

DESCRIPTION OF SYMBOLS 1 ... Exterior material for electrical storage devices 2 ... Polyamide resin layer (outer layer)
3 ... Heat-fusible resin layer (inner layer)
4 ... Metal foil layer 10 ... Exterior case 15 ... Exterior member 30 ... Power storage device 31 ... Power storage device body

Claims (2)

An exterior material for an electricity storage device comprising a polyamide resin layer as an outer layer, a heat-fusible resin layer as an inner layer, and a metal foil layer disposed between these two layers,
In the polyamide resin, the onset temperature derived from the melting heat distribution curve obtained by differential scanning calorimetry of the polyamide resin is “Y” (° C.), and the melting point of the polyamide resin derived from the melting heat distribution curve is “X”. "(℃),
X−Y ≦ 3.0
And X ≧ 218
An exterior material for an electricity storage device, which is a polyamide resin satisfying the relational expression: An electricity storage device body,
An exterior member including the exterior material for an electricity storage device according to claim 1,
The electricity storage device, wherein the electricity storage device body is covered with the exterior member.

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