JP5308753B2 - Power storage device container - Google Patents

Description

  The present invention relates to a container for a power storage device for housing a power generation element. More specifically, the present invention relates to a container for a power storage device that is excellent in moisture resistance and lightweight, and has an excellent performance balance of chemical resistance, pressure resistance, and creep resistance.

  Conventionally, a metal material has been frequently used as a container for storing a power generation element in a power storage device such as a lithium ion secondary battery because of its excellent heat and moisture resistance and creep resistance. However, when the material is a metal, there is a problem that the weight of the container increases, and man-hours are required for welding the container and the lid, which is also a problem from the viewpoint of mass productivity. In particular, when the material of the container is aluminum, welding by a method other than laser welding is impossible, and this laser welding has a problem that it takes time.

In order to reduce the weight, a container is formed of a resin such as polypropylene or polyethylene. Among the resins, polypropylene has been conventionally used because of its excellent moisture resistance and chemical resistance and excellent moldability. However, when the polypropylene resin is used as a container for a lithium ion secondary battery, it is not necessarily sufficient in terms of mechanical strength and heat resistance, and there is a problem in long-term reliability such as creep resistance. . Furthermore, the present situation is that a container for a lithium ion secondary battery used in the automobile field or the like is required to have moisture resistance substantially higher than the moisture permeability of the resin itself. In addition, it is known that the water vapor permeability (moisture permeability) of the polypropylene resin and the polyethylene resin has the following values under conditions of 25 ° C. and a relative humidity of 90%. Low density polyethylene (thickness 30 μm); 18 g / m ² · 24 hr, high density polyethylene (thickness 30 μm); 7 g / m ² · 24 hr, unstretched polypropylene (thickness 30 μm); 8 g / m ² · 24 hr, stretched polypropylene (thickness 20 μm) ); 5 g / m ² · 24 hr (see Non-Patent Document 1).

And as a container for secondary batteries using a resin container, what laminated | stacked the moisture-proof aluminum foil on the outer peripheral surface of the resin container is disclosed (for example, refer patent document 1).
However, the container of Patent Document 1 cannot be said to have sufficient moisture resistance, and cannot be used for a non-aqueous electrolyte such as a lithium ion secondary battery. is there. Furthermore, the mechanical strength is not sufficient.

  In particular, in a lithium ion secondary battery, since the electrolytic solution is non-aqueous and uses an ester organic solvent, there is a problem that electromotive force is lowered when moisture enters from the outside of the container. Further, when lithium and water come into contact with each other, there is a problem that heat is generated by a chemical reaction, causing deterioration of battery characteristics, and the internal pressure of the container is increased by hydrogen generated by the reaction. Therefore, the container of the lithium ion secondary battery is required to have higher moisture resistance that blocks moisture from the outside. Furthermore, as the technology of the lithium ion secondary battery used in the automotive field such as a hybrid car where the latest technology is used every day as the technology advances, it not only has excellent moisture resistance but also has chemical resistance, pressure resistance and Under the present circumstances, a material having an excellent balance of creep resistance is required.

  Further, in a container for a lithium ion secondary battery in which a metal material is used, the container itself can be used as an electrode. For example, in a cylindrical lithium ion secondary battery, it is known that positive electrodes and negative electrodes are formed by insulating a convex lid and a metallic cylindrical container. ing. On the other hand, when the material of the cylindrical container is resin, the container itself is insulated, so that it is necessary to provide a through hole through which the two electrodes pass through the container. Therefore, the container for the secondary battery made of resin is required to have excellent pressure resistance and creep resistance even if a through hole for passing an electrode is provided.

  Based on the above, there is a need for a container for a power storage device such as a lithium ion secondary battery that is lighter than a metal container, has excellent moisture resistance, and has an excellent balance of chemical resistance, pressure resistance, and creep resistance. ing.

JP 2004-281156 A The latest functional practical dictionary, edited by Ministry of Agriculture, Forestry and Fisheries, published by Fuji Techno System, P270, Table 10.11

  The present invention has been made in view of the above circumstances, and is excellent in moisture resistance and light weight, and has an excellent performance balance of chemical resistance, pressure resistance, heat dissipation, creep resistance and electrical insulation, and manufacturing cost. An object of the present invention is to provide a container for a power storage device in which the amount of electricity is reduced.

The present invention is as follows.
[1] A container for a power storage device for housing a power generation element,
(A) a resin container body having an opening, (B) a coating layer formed of a laminated film having an aluminum foil layer and covering the outer surface of the container body, and (C) the container body And (D) a lid covering layer that covers the outer surface of the lid, and the proof stress of the aluminum foil layer in the laminated film is 120 to 300 N / mm ^2. , and the Ri and elongation of 2.0 to 10.0% der,
The resin constituting the container body is a polypropylene polymer,
(1) The polypropylene polymer is a propylene homopolymer, or
(2) The polypropylene polymer is a mixture of a propylene homopolymer and a propylene-ethylene block copolymer, and the content of the propylene homopolymer in the mixture is 100% by mass of the polypropylene polymer. The container for a power storage device is characterized by being 93% by mass or more and less than 100% by mass .
[ 2 ] The container for a power storage device according to [1], wherein the laminated film includes a laminate in which a thermoplastic resin layer, an aluminum foil layer, and a thermoplastic resin layer are sequentially laminated.
[ 3 ] The resin constituting the container body is a mixture of a propylene homopolymer and a propylene-ethylene block copolymer, and the coating layer is a laminate in which a polypropylene layer, an aluminum foil layer, and a polypropylene layer are sequentially laminated. The container for a power storage device according to the above [1], which is formed by a laminated film comprising:
[ 4 ] Any one of [1] to [ 3 ], wherein a seal layer is provided at a joint between the container body and the lid, and the seal layer is formed of a laminated film having an aluminum foil layer. A container for a power storage device according to claim 1.
[ 5 ] The power storage device container according to any one of [1] to [ 4 ], wherein the coating layer is formed by spirally winding the laminated film on the outer surface of the container body.

The container for a power storage device of the present invention includes a coating layer having an aluminum foil layer on the outer surface of a resin-made container body, and a lid covered with the coating layer. Excellent balance of performance, pressure resistance and creep resistance.
Moreover, since the proof stress of the said aluminum foil layer is 120-300 N / mm < ² > and elongation is 2.0-10.0%, the coating layer which has an aluminum foil layer is not only a moisture-proof member but a container main body It can act as a reinforcing member, and the strength such as pressure resistance in the container can be further improved. Furthermore, the thickness of the resin constituting the container body can be set thin (for example, a thickness of 0.9 to 1.1 mm) while sufficiently maintaining strength such as pressure resistance. Therefore, the size of the power storage device container can be reduced and the weight of the container can be reduced. Especially in the automotive field where hundreds or more lithium ion secondary batteries are mounted, the installation space required for the secondary battery can be reduced by reducing the size and weight of the container. Can be achieved.
Furthermore, since the resin constituting the container body is a specific polypropylene polymer, than with other resins, it is possible to improve moisture resistance, chemical resistance and heat resistance, and relatively large Strength can be obtained.
In addition, when the coating layer is formed of a laminated film composed of a laminate in which a thermoplastic resin layer, an aluminum foil layer, and a thermoplastic resin layer are sequentially laminated, the outer surface of the container body is thermally fused or the like. Can be easily joined.
Furthermore, when the sealing part formed of the laminated film which has an aluminum foil layer is provided in the joint part of a container main body and a cover body, the moisture-proof property of the container for electrical storage devices can be improved more.
Further, when the coating layer in the power storage device container is formed by spirally winding a laminated film on the outer surface of the container body, the pressure resistance and creep resistance can be further improved. Furthermore, the strength of the entire container against the internal pressure can be made more uniform.

Hereinafter, embodiments of the present invention will be described in detail.
A container for a power storage device of the present invention is a container for housing a power generation element, and (A) a resin container main body having an opening, and (B) a coating layer formed on the outer surface of the container main body. And (C) a lid that closes the opening, and (D) a coating layer formed on the outer surface of the lid.

Said constitutes a "container body", "resin" is a polypropylene polymer. This polypropylene polymer is preferable because it is excellent in moisture resistance, chemical resistance and heat resistance among the resins and has a relatively large strength.
This polypropylene polymer may be composed only of a propylene homopolymer, or may be a mixture of a propylene homopolymer and another polymer.
Examples of the other polymer include a propylene homopolymer portion obtained in the first step of polymerization of polypropylene homopolymer, and propylene, ethylene and / or at least one other α-olefin (for example, butene in the second step of polymerization). -1, hexene-1, etc.) and a propylene-ethylene random copolymer portion obtained by copolymerization.

The content of the propylene homopolymer in the polypropylene polymer is preferably 93 % by mass or more, particularly preferably 93 to 98% by mass when the polypropylene polymer is 100% by mass. When this content rate is 90 mass%, the moisture-proof property, chemical-resistance, and intensity | strength of the container for electrical storage devices can be improved more. In particular, when the content ratio is 93 to 98% by mass, moisture resistance, chemical resistance, and strength of the power storage device container can be reliably improved.

  In the present invention, the polypropylene polymer is a mixture of a propylene homopolymer and a propylene-ethylene block copolymer, and when the total of both is 100% by mass, the content of the propylene homopolymer is It can be 93-98 mass%. In this case, moisture resistance, chemical resistance, and strength of the power storage device container can be reliably improved.

Moreover, it is preferable that the polystyrene conversion weight average molecular weight (Mw) measured by the gel permeation chromatography (GPC) of the said propylene homopolymer is 200,000-800,000, More preferably, it is 550,000- 650,000. Furthermore, the ratio (Mw / Mn) between the Mw of this propylene homopolymer and the polystyrene-equivalent number average molecular weight (hereinafter also referred to as “Mn”) measured by GPC is preferably 2.5 to 6.0. .
Moreover, it is preferable that the weight average molecular weights measured by GPC of the said propylene-ethylene block copolymer are 200,000-800,000, More preferably, it is 400,000-700,000. Furthermore, it is preferable that Mw / Mn of this propylene-ethylene block copolymer is 3.0 to 7.5.

Further, the resin constituting the container body preferably has a yield point stress of 35 MPa or more, more preferably 40 MPa or more. When the yield point stress is 35 MPa or more, the pressure resistance and creep resistance of the power storage device container can be further improved.
The yield point stress is a value measured at room temperature (23 ° C.) using JIS K 7113-1995 test piece No. 2 and a test speed of 10 mm / min.

Furthermore, the density of the resin is preferably 0.89 to 0.91 g / cm ³ . This density is a value measured according to JIS K7112: 1999 (Plastic—Method for measuring density and specific gravity of non-foamed plastic).

  In addition, the manufacturing method of the said resin is not specifically limited, It can synthesize | combine by a well-known polymerization method.

The shape of the container body is not particularly limited as long as it has an opening and can store the power generation element. For example, the container body can have a cylindrical shape. The cross-sectional shape of the cylindrical container body (cylindrical body) is not particularly limited, and may be a circular shape, an elliptical shape, a polygonal shape, or the like.
Moreover, the formation position of the said opening part, the number of formation, and opening shape are not specifically limited. In particular, when the container body is a cylindrical body, it is preferable that an opening having one or both ends opened is formed.

Also, the dimensions such as the thickness and length of the container main body are not particularly limited, and can be appropriately adjusted as necessary.
In the present invention, the thickness of the container body, that is, the thickness of the resin constituting the body is, for example, 0.5 to 1.5 mm, particularly 0.8 to 1.2 mm, and further 0.9 to 1.1 mm. can do.

  The manufacturing method of the said container main body is not specifically limited, For example, it can manufacture by the extrusion molding method, the injection molding method, the blow molding method etc. using the above-mentioned resin. In particular, when a cylindrical body having openings at both ends is molded, it is preferable to use an extrusion molding method from the viewpoint of obtaining a cylindrical body with excellent dimensional accuracy.

The outer surface of the container body is covered with the “coating layer”, and this coating layer is formed of a laminated film having an aluminum foil layer.
The laminated film is preferably made of a laminate of an aluminum foil layer and a resin layer. Examples of the laminate include a laminate of a thermoplastic resin layer and an aluminum foil layer, and the thermoplastic resin layer side is usually bonded to the outer surface of the container body by thermal fusion or the like. . In particular, as such a laminated film, a laminated body in which a thermoplastic resin layer, an aluminum foil layer, and a thermoplastic resin layer are sequentially laminated is preferable. In addition, when the laminated film has a plurality of thermoplastic resin layers, each thermoplastic resin layer may be composed of the same resin or may be composed of different resins. Moreover, when both surfaces are thermoplastic resin layers, either side may be joined to the outer surface of the container main body.
Moreover, as resin which comprises the said thermoplastic resin layer, polyethylene, a polypropylene, etc. are mentioned, for example.
In particular, as a specific laminated film used in the present invention, a film composed of a laminate in which a polypropylene layer, an aluminum foil layer, and a polypropylene layer are sequentially laminated can be exemplified.

The film thickness of the laminated film (that is, the total thickness obtained by adding the film thicknesses of the respective layers) is not particularly limited, and can be appropriately adjusted as necessary. This film thickness can be, for example, 50 to 130 μm, particularly 70 to 110 μm.
The film thickness of the aluminum foil layer in this laminated film is not particularly limited, and can be appropriately adjusted as necessary. The film thickness can be, for example, 20 to 70 μm, particularly 20 to 60 μm, and further 30 to 50 μm.
Moreover, the film thickness (film thickness in a single layer) of the resin layer in the laminated film is not particularly limited, and can be appropriately adjusted as necessary. The film thickness can be, for example, 10 to 55 μm, particularly 13 to 30 μm, and further 15 to 25 μm. In addition, the thickness of each resin layer in a laminated | multilayer film may be the same, and may differ.

Moreover, in the said laminated | multilayer film, the yield strength of an aluminum foil layer is 120-300 N / mm < ² >. When the proof stress is 120 N / mm ² or more, the container is not deformed even when a constant stress is applied, and the creep resistance can be further improved.

Further, in the laminated film, elongation Ri from 2.0 to 10.0% der, more preferably 2.2 to 9.2%. When the elongation is 2.0 to 10.0%, the pressure resistance can be further improved without tearing the container even when the internal pressure is applied and the elongation occurs.
The proof stress and elongation were set using a Tensilon (Orientec Co., AMF / RTA-100) with a laminated film having a width of 15 mm so that the length between chucks was 10 mm, and 25 ° C. and 65%. It is a value measured by conducting a tensile test at a tensile speed of 1 mm / min under the condition of RH.

The coating layer may be formed in any form on the outer surface of the container body. For example, as shown in FIG. 1, the covering layer 3 can be formed by winding a laminated film in the circumferential direction of the container body so that the overlap margin 34 is formed.
Furthermore, in order to further improve the pressure resistance and creep resistance, and to make the strength of the entire container against the internal pressure more uniform, as shown in FIG. 7, the covering layer 3 has a laminated film on the outer surface of the container body. It can be formed by spirally winding so that the overlap margin 34 is formed.

Further, the moisture permeability of the container body on which such a coating layer is formed can be 0.95 mg / m ² · 24 hr or less. The moisture permeability is a value measured by the method described in the examples described later.
When this moisture permeability is 0.95 mg / m ² · 24 hr or less, even if it is used for a long period of time as a container for a power storage device, the accumulated amount of moisture permeated during that period is very small. And can be used as a container for a power storage device even in an environment mounted on a vehicle.

  In particular, in the container for a power storage device of the present invention, the thickness of the container body is 0.5 to 1.5 mm, the thickness of the laminated film is 70 to 110 μm, and the aluminum foil layer in the laminated film The film thickness can be 20 to 70 μm.

  Moreover, in the container for a power storage device of the present invention, the resin constituting the container body is a mixture of a propylene homopolymer and a propylene-ethylene block copolymer, and the covering layer includes a polypropylene layer, an aluminum foil layer and a polypropylene layer Can be formed by a laminated film made of a laminated body in which are sequentially laminated. The laminate in which the polypropylene layer, the aluminum foil layer, and the polypropylene layer are sequentially laminated can be formed by a known laminating method. Specifically, for example, the laminate can be obtained by using a cylindrical battery part manufactured by Hosen Co., Ltd. or a battery packaging material manufactured by Dai Nippon Printing Co., Ltd.

Furthermore, the power storage device container according to the present invention includes a “lid” that closes the opening of the container body.
The lid is usually made of a resin, and the type of the resin is not particularly limited, and examples thereof include general resins such as a polypropylene-based polymer. In particular, a material that can be easily joined to the container main body by a method such as heat fusion or ultrasonic fusion and that can be joined to the container main body without any gap is preferable.

The shape of the lid is not particularly limited as long as the opening of the container body can be closed. Specifically, for example, an entire diameter (outer diameter) of the opening in the container body is covered, and an end having a diameter matching the outer diameter and a cylindrical contact portion inserted into the opening are provided. Things. Note that the shape of the contact portion is appropriately selected according to the shape of the opening, and may be cylindrical, rectangular tube, or the like.
When the lid body covers the entire outer diameter of the opening in the container body and includes an end having a diameter that matches the outer diameter, the entire body can be covered with a laminated film, and the opening of the container body It is possible to sufficiently prevent the portion from coming into contact with the outside air and to obtain high moisture resistance (moisture resistance).
Furthermore, when the said cover body is provided with the cylindrical contact part inserted in the said opening part, the adhesiveness and fitting strength of a cover body and a container main body can be improved more.

The outer surface of the lid is covered with the “lid covering layer”. Therefore, the moisture resistance of the power storage device container according to the present invention can be sufficiently ensured.
The said cover body coating layer shall be formed with the laminated | multilayer film which has an aluminum foil layer. As this laminated film, the same thing as the laminated film which forms the coating layer which coat | covers the above-mentioned container main body can be mentioned.
In addition, the laminated film which comprises the coating layer which coat | covers a container main body, and the laminated film which comprises a cover body coating layer may be the same, and may differ.

  As a specific lid body provided with the lid body covering layer, for example, as shown in FIG. 5, the entire outer diameter of the container body (tubular body) on which the covering layer is formed is covered with the outer diameter. An end 412 having a diameter (diameter), a lid covering layer 42 covering the surface of the end 412, and an opening of the cylindrical body (see the opening 21 in FIG. 2) can be inserted and fitted. The thing provided with the cylindrical contact part 411 is mentioned. Furthermore, in order to further improve the bonding strength between the lid and the cylindrical body and the moisture resistance of the container, the area of the lid covering layer 42 is made larger than the surface area of the end surface portion of the lid 4 as shown in FIG. And those having the joint reinforcing portion 421 formed as described above.

When such a lid is provided, the lid and the container body (tubular body) are: (1) the inner peripheral surface of the opening of the cylindrical body and the outer peripheral surface of the contact portion of the lid (a in FIG. 6). And (2) between the end surface of the opening of the cylindrical body and the back surface of the end of the lid (see the b surface of the end 412 in FIG. 6). It is joined by fusion and has a sufficient joining strength.
The outer diameter of the cross section of the contact portion is not limited as long as a gap is not formed between the cylindrical portions when bonded, but considering volume changes due to resin melting during thermal fusion or ultrasonic fusion. However, it is usually designed to be larger than the inner diameter of the opening of the cylindrical body by the bonding allowance.

Moreover, the area of the outer peripheral surface of the contact portion in the lid (refer to the surface a of the contact portion 411 in FIG. 6) to be joined to the inner peripheral surface of the opening of the cylindrical body is 150 to 800 mm ² . It is preferably 400 to 600 mm ² . When this area is 150 to 800 mm ² , the bonding strength between the lid and the cylindrical body can be further improved.

Moreover, the said cover body is normally provided with the through-hole (refer the through-hole 43 in FIG.1, FIG.4, FIG.5 etc.) for providing the electrode of a lithium ion secondary battery. One through hole may be formed in each of the lids on both ends, or two may be formed in the lid on one side. Especially, it is preferable that one through-hole is formed in the center of the lid body at both ends.
In the present invention, even if a through-hole is formed in the lid, the strength of the power storage device container is improved and the moisture resistance is excellent by adopting the above-described fitting structure for joining the lid and the container body. At the same time, a container for a power storage device having an excellent performance balance of chemical resistance, pressure resistance and creep resistance can be obtained.

  In addition, the said cover body can be obtained by laminating | stacking a laminated film on the resin molding manufactured by the extrusion molding method, the injection molding method, the blow molding method etc.

Furthermore, in the container for a power storage device of the present invention, a seal layer can be provided at a joint portion between the container body and the lid that is generated when the lid is disposed. When this seal layer is provided, moisture permeation due to the joint portion can be suppressed, and the moisture resistance of the power storage device container can be further improved.
This sealing layer can be usually formed by winding a laminated film serving as a sealing layer around the container body and heat-sealing so that the joint between the container body and the lid is covered. When such a sealing layer is provided, sufficient moisture resistance can be ensured even when the joint reinforcing portion 421 (see FIGS. 4 and 5) is not formed on the lid 4. Further, even when the joint reinforcing portion 421 is formed, higher moisture resistance can be obtained by providing a seal layer (see the seal layer 5 in FIG. 1). In particular, when the peripheral edge of the lid head is rounded, it is preferable to cover the container main body with a joint reinforcing portion and wind the laminated film to form a seal layer at the joint.

  Moreover, as a laminated film for forming the said sealing layer, it is preferable to use the laminated film which has an aluminum foil layer. As this laminated film, the same thing as the laminated film which forms the coating layer formed in the above-mentioned container main body can be mentioned. In particular, the thickness of the aluminum foil layer in this seal layer is preferably 20 μm or more. In addition, the laminated film which comprises the coating layer formed in the container main body, and the laminated film which comprises a sealing layer may be the same, and may differ.

  In addition, the “power generation element” housed in the container for the power storage device of the present invention is not particularly limited, and various secondary batteries such as conventionally known lithium ion secondary batteries, non-aqueous electrolysis A power generation element housed in a power storage device such as a capacitor having a liquid can be given.

Hereinafter, the present invention will be described in detail with reference to the drawings.
[1] Configuration of power storage device container (lithium ion secondary battery container)
<Embodiment 1>
As shown in FIGS. 1-3, the container 1 for lithium ion secondary batteries of this Embodiment 1 is a product made from resin, the cylindrical container main body 2 and the coating layer formed in the outer surface of this container main body 2 3, a resin lid 4 inserted into the opening 21 of the container body 2, a lid covering layer 42 formed on the outer surface of the lid 4, and a seal layer 5. Yes.
The said container main body 2 is formed by the extrusion molding method, The dimension is cylinder length; 194 mm, outer diameter; 23.5 mm, resin thickness; 1.00 mm.
The resin constituting the container body 2 is a propylene homopolymer or a mixture of a propylene homopolymer and a propylene-ethylene block copolymer.
As shown in FIGS. 1 to 3, the coating layer 3 is a laminate in which a polypropylene layer 31, an aluminum foil layer 32, and a polypropylene layer 33 are sequentially laminated [thickness of each layer; 20/30 to 50/20 (μm). The polypropylene layer 31 is joined to the outer peripheral surface of the container body 2 by heat fusion.

As shown in FIGS. 2 and 4, the lid 4 covers the entire outer diameter of the container body 2 on which the covering layer 3 is formed, and has an end 412 having a diameter that matches the outer diameter, and the end 412 In order to improve the bonding strength between the lid 4 and the container body 2, the lid covering layer 42 covering the surface of 412, the cylindrical contact portion 411 that can be inserted and fitted into the opening 21 of the container body 2. The joint reinforcement part 421 is provided.
The resin constituting the lid 4 is a polypropylene polymer.
Further, the lid covering layer 42 is formed of a laminated film composed of a laminate [thickness of each layer; 20/30/20 (μm)] in which a polypropylene layer, an aluminum foil layer, and a polypropylene layer are sequentially laminated. In addition, a bonding reinforcing portion 421 that can be heat-sealed to the outer peripheral surface of the coating layer 3 formed on the container body 2 is provided.
In addition, each lid body 4 provided at both ends is formed with one through hole 43 at the center position of each end face for arranging electrodes in the lithium ion secondary battery.
And this cover body 4 is the inner peripheral surface and end surface of the opening part 21 of the container main body 2, respectively, the outer peripheral surface (refer a surface in FIG. 6 (refer to the b surface of the end portion 412). In addition, the joining area of the outer peripheral surface (the said a surface) of the contact part 411 is 486 mm < ² >. Furthermore, the bonding area of a part of the back surface of the end portion 412 (the b surface) is 70 mm ² .

  The sealing layer 5 is formed of a laminated film composed of a laminate [thickness of each layer; 20/30/20 (μm)] in which a polypropylene layer, an aluminum foil layer, and a polypropylene layer are sequentially laminated. As shown in FIGS. 1 to 3, the seal layer 5 is joined by heat fusion to a joint between the joint reinforcing portion 421 in the lid body 4 and the container body 2 on which the coating layer 3 is formed. .

[2] Performance Evaluation of Power Storage Device Container The power storage device containers of Test Examples 1 to 15 having the following configurations were manufactured, and various performance evaluations described below were performed.
<Test Examples 1-15>
Test Examples 1 to 1 having the same configuration as in Embodiment 1 except that the resin constituting the container body 2 in Embodiment 1 and the aluminum foil layer constituting the coating layer 3 were those shown in Table 1. Fifteen lithium ion secondary battery containers were obtained.
In addition, “proof strength” and “elongation” of the aluminum foil layer in Table 1 are measured by the above-described measuring methods. Table 1 also shows “breaking strength” and “yield point stress” of each resin constituting the container body 2. This breaking strength was measured by measuring the pressure at the time of breaking the container body before forming the coating layer in 60 ° C warm water using the water pressure test pump until the container breaks. It is. The yield point stress is measured by the above-described measuring method.

The following performance evaluation was performed on the secondary battery containers according to Test Examples 1 to 15, and the results are shown in Table 2.
<Moisture resistance>
The weight (mg) changed when allowed to stand for 20 days in an atmosphere of a temperature of 40 ° C. and a relative humidity of 90%, (A) a container is filled with a hygroscopic material (calcium chloride), and lids on both ends When the through-hole is sealed, and (B) when the moisture-absorbing material is not added and the through-holes on both ends are sealed, the moisture permeability (mg) is calculated from the difference [(B)-(A)]. / M ² · 24 hr).

<Chemical resistance>
The test piece was immersed in a 60 ° C. ethylene carbonate and 10% hydrofluoric acid solution [mixed solution of ethylene carbonate and hydrofluoric acid (hydrofluoric acid concentration: 10% by volume)] for 2 weeks, and the rate of change in tensile strength of the test piece before and after immersion. I investigated. The test piece was dumbbell No. 3 conforming to JIS, with a pulling speed of 10 mm / min and a distance between chucks of 70 mm. And chemical resistance was evaluated according to the following criteria.
“◎”: When the rate of change in tensile strength is 10% or less “×”: When the rate of change in tensile strength exceeds 10%

<Pressure resistance (breaking strength)>
After sealing one end of the container with a plug, attach a water pressure test pump hose to the other end and seal it to prevent water leakage. After that, by continuously feeding tap water to the container in 60 ° C warm water, the inside of the container is continuously pressurized, water is sent until the container breaks, and the water pressure (breaking strength) at the time of breaking is measured. The pressure resistance was evaluated.
“◎”: When the breaking strength is 3.0 MPa or more “◯”: When the breaking strength is 2.8 MPa or more and less than 3.0 MPa “△”; When the breaking strength is 2.6 MPa or more and less than 2.8 MPa “ × ”: When the fracture strength is less than 2.6 MPa

<Creep resistance>
After sealing one end of the container with a plug, attach a water pressure test pump hose to the other end and seal it to prevent water leakage. Then, in 60 degreeC warm water, the pressure of 1.0MPa and 1.5MPa was alternately applied in the container every 30 minutes using the water pressure test pump, and the destructive test was conducted for a maximum of 500 hours. That is, a maximum of 500 cycles was performed with one cycle of 1.0 MPa-1.5 MPa for 30 minutes each. And the creep resistance was evaluated according to the following criteria.
“◎”: not destroyed or destroyed in 500 to 700 cycles “◯”; destroyed in 200 to 499 cycles “Δ”; destroyed in 100 to 199 cycles “×”; destroyed in 99 cycles or less

[3] Effect of Test Example According to Table 2, the secondary battery containers of Test Examples 1 to 15 have considerably high moisture permeability (0.92 to 0.95 mg / m ² · 24 hr). It can be seen that there is a difference of 1000 times or more compared to moisture permeability (see Non-Patent Document 1) such as polyethylene and polypropylene which are said to be excellent in moisture resistance among resins. This is also apparent from the difference between the units [unit of moisture permeability of the secondary battery container in the test example; mg / m ² · 24 hr, unit of moisture permeability (water vapor permeability) of the resin; g / M ² · 24 hr]. Therefore, each secondary battery container of the test example can keep the accumulated amount of permeated moisture very small when used for a long time.
Further, since these secondary battery containers are made of resin, they are lighter than metal materials and can be manufactured at low cost.
In particular, according to Table 2, it can be seen that the secondary battery containers of Test Examples 2 to 9, 13 and 14 are excellent in the performance balance of chemical resistance, pressure resistance and creep resistance. Therefore, it is also suitable as a container for a lithium ion secondary battery that is used for a long time in the automobile field or the like.

  Note that the present invention is not limited to the specific embodiments described above, and various modifications can be made within the scope of the present invention depending on the purpose and application. For example, as shown in FIG. 7, a container for a power storage device (lithium ion) formed by spirally winding the covering layer 3 on the outer peripheral surface of the container main body so as to form an overlapping portion 34. It can be set as the container 1) for secondary batteries. Further, as shown in FIG. 8, a lid 4a having two through holes 43 for electrodes is disposed on one end side, and a lid 4b having no through holes 43 is disposed on the other end side. In addition, a power storage device container (lithium ion secondary battery container 1) in which electrodes necessary for the lithium ion secondary battery can be disposed only on one side can be obtained.

It is a schematic diagram explaining the container for electrical storage apparatuses of this invention. It is a disassembled perspective view which illustrates typically the container for electrical storage apparatuses of this invention. It is a schematic diagram explaining the cross section of the container for electrical storage apparatuses. It is a schematic diagram explaining the cross section of a cover body. It is a schematic diagram explaining the cross section of a cover body. It is a schematic diagram explaining the cross section of a cover body. It is a schematic diagram explaining the coating layer formed in spiral. It is a schematic diagram explaining the container for electrical storage apparatuses of the other form in this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1; Container for electrical storage devices, 2; Container main body, 21; Opening part, 3; Coating layer, 31; Polypropylene layer, 32; Aluminum foil layer, 33: Polypropylene layer, 34; Lid body, 411; contact portion, 412; end portion, 42; lid body covering layer, 421; joint reinforcing portion, 43; through hole, 5;

Claims (5)

A container for a power storage device for housing a power generation element,
(A) a resin container body having an opening;
(B) a coating layer that is formed of a laminated film having an aluminum foil layer and covers the outer surface of the container body;
(C) a lid that closes the opening in the container body;
(D) a lid covering layer that covers the outer surface of the lid,
The yield strength of the aluminum foil layer in the laminated film is a 120~300N / mm ^2, Ri and elongation from 2.0 to 10.0% der,
The resin constituting the container body is a polypropylene polymer,
(1) The polypropylene polymer is a propylene homopolymer, or
(2) The polypropylene polymer is a mixture of a propylene homopolymer and a propylene-ethylene block copolymer, and the content of the propylene homopolymer in the mixture is 100% by mass of the polypropylene polymer. The container for a power storage device is characterized by being 93% by mass or more and less than 100% by mass .   The container for a power storage device according to claim 1, wherein the laminated film is composed of a laminate in which a thermoplastic resin layer, an aluminum foil layer, and a thermoplastic resin layer are sequentially laminated.   The resin constituting the container body is a mixture of a propylene homopolymer and a propylene-ethylene block copolymer, and the coating layer is a laminate formed by sequentially laminating a polypropylene layer, an aluminum foil layer, and a polypropylene layer. The power storage device container according to claim 1, wherein the power storage device container is formed of a film. It comprises a sealing layer at the joint portion between the lid and the container body, and the sealing layer, the electric storage device according to any one of claims 1 to 3 is formed by a laminated film having an aluminum foil layer Container. The power storage device container according to any one of claims 1 to 4 , wherein the covering layer is formed by spirally winding the laminated film on an outer surface of the container main body.

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