JP2024007195A - Laminate outer packaging material for power storage device, power storage device and assembled power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminate outer packaging material for a power storage device, which can absorb the volume expansion caused by actions of charging/discharging a power storage device, and lighten a stress applied to a power storage element, and a power storage device having such a laminate outer packaging material, and an assembled power storage device.

SOLUTION: A laminate outer packaging material for a power storage device comprises an outer layer, an inner layer and a barrier layer disposed therebetween. At least one of the outer layer and the inner layer includes a porous layer. A power storage device comprises: a power storage element having a positive electrode, a negative electrode and an electrolyte; and a laminate outer packaging material for a power storage device, packaging the power storage element from outside, and having an outer layer, an inner layer and a barrier layer disposed therebetween. The power storage device is arranged by sealing together parts of the inner layer of the laminate outer packaging material for the power storage device along a periphery of the power storage element in a state in which a positive electrode tab of the positive electrode, and a negative electrode tab of the negative electrode are led to outside; at least one of the outer layer and the inner layer includes a porous layer.

SELECTED DRAWING: Figure 3

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to a laminate exterior material for a power storage device, a power storage device, and an assembled power storage device, and more particularly, a laminate for a power storage device that can absorb volumetric expansion due to charging and discharging of a power storage device and reduce stress applied to a power storage element. The present invention relates to an exterior packaging material, a power storage device including the same, and an assembled power storage device.

Conventionally, a laminate material has been proposed in which the amount of lubricant transferred from the inner layer to the outer layer is controlled so as not to reduce the adhesion of the adhesive tape (see Patent Document 1). The laminate includes an outer layer, an inner layer, and a metal foil layer disposed between the outer and inner layers. The inner layer consists of one layer or multiple layers. The innermost layer of the inner layer is made of a resin composition containing a heat-fusible resin and a lubricant, and has a lubricant concentration of 1000 ppm to 5000 ppm. The inner layer has, on the surface of its innermost layer, a convex portion that is 0.3 μm or more higher than the reference height per 1 mm ² when the average value of the surface height is the reference height.

Furthermore, an exterior material for a power storage device having a surface with high slipperiness and high adhesion to an adhesive tape has been proposed (see Patent Document 2). This exterior material for a power storage device includes a layered structure including an outermost layer, a sealant layer, and a barrier layer disposed between both layers. The outermost layer is made of at least one selected from the group consisting of polyamide film, polyester film, and polyolefin film. Concerning the surface properties of the surface of the outermost layer, a convex portion whose arithmetic mean height Sa is in the range of 0.03 to 0.20 μm and whose cross-sectional area at a height position of +0.1 μm from the reference plane of Sa is 7500 μm ² or more. When defined as a peak, the number of peaks is in the range of 5 to 30 per 1 ^mm2 .

Japanese Patent Application Publication No. 2020-11409 JP2020-21727A

However, when a laminate exterior material having an uneven structure on the surface as described in Patent Document 1 and Patent Document 2 is used for a power storage device that expands in volume due to charging and discharging, stress applied to the power storage element due to the volumetric expansion of the power storage device There was a problem in that the cost would be high.

The present invention has been made in view of the problems of the prior art, and provides a laminate exterior material for a power storage device that can absorb volumetric expansion due to charging and discharging of the power storage device and reduce stress applied to the power storage element. It is an object of the present invention to provide a power storage device and an assembled power storage device equipped with this.

As a result of extensive studies to achieve the above object, the inventors of the present invention have achieved the above object by creating a structure in which at least one of the outer layer and the inner layer of the laminate exterior material for power storage devices includes a porous layer. The present inventors have discovered that this can be achieved, and have completed the present invention.

That is, the laminate exterior material for a power storage device of the present invention has an outer layer, an inner layer, and a barrier layer disposed between them.
At least one of the outer layer and the inner layer includes a porous layer.

Further, the power storage device of the present invention includes a power storage element having a positive electrode, a negative electrode, and an electrolyte, and a laminate exterior material for a power storage device that covers the power storage element and has an outer layer, an inner layer, and a barrier layer disposed between these. The inner layers of the laminate exterior material for a power storage device are sealed together along the periphery of the power storage element while the tabs of the positive electrode and the negative electrode remain exposed to the outside.
At least one of the outer layer and the inner layer includes a porous layer.

Moreover, the assembled electricity storage device of the present invention is made up of a plurality of flat electricity storage devices stacked in the thickness direction of the electricity storage device.
This power storage device includes a power storage element having a positive electrode, a negative electrode, and an electrolyte, and a laminate exterior material for a power storage device that covers the power storage element and has an outer layer, an inner layer, and a barrier layer disposed between these. The inner layers of the laminate exterior material for a power storage device are sealed together along the periphery of the power storage element while leaving the tab of the negative electrode exposed to the outside.
In at least one of the plurality of power storage devices, at least one of the outer layer and the inner layer includes a porous layer.

According to the present invention, since at least one of the outer layer and the inner layer of the laminate exterior material for a power storage device includes a porous layer, volumetric expansion due to charging and discharging of the power storage device is absorbed and stress applied to the power storage element. It is possible to provide a laminate exterior material for a power storage device that can reduce the amount of damage, and a power storage device and assembled power storage device equipped with the same.

1 is a perspective view schematically showing an embodiment of a power storage device of the present invention. FIG. 2 is a schematic cross-sectional view of the electricity storage device shown in FIG. 1 taken along line II-II. FIG. 2 is a partial cross-sectional view schematically showing a portion of the laminate exterior material for a power storage device shown in FIG. 1 surrounded by line III. It is a partial sectional view showing typically a part of the 1st modification of the laminate exterior material for electricity storage devices. It is a partial sectional view showing typically a part of the 2nd modification of the laminate exterior material for electricity storage devices. It is a partial sectional view showing typically a part of the 3rd modification of the laminate exterior material for electricity storage devices. FIG. 2 is a side view schematically showing the electricity storage device shown in FIG. 1. FIG. 1 is a partial sectional view schematically showing a part of an embodiment of an assembled power storage device of the present invention.

Hereinafter, the laminate exterior material for a power storage device, the power storage device, and the assembled power storage device of the present invention will be described in detail with reference to the drawings. In addition, although a lithium ion secondary battery and its assembled battery are illustrated and demonstrated as an electricity storage device and an assembled electricity storage device, this invention is not limited to these. Furthermore, hereinafter, the "laminate exterior material for lithium ion secondary batteries" may be simply referred to as "laminate exterior material." Furthermore, the dimensional proportions in the drawings cited below are exaggerated for illustrative purposes and may differ from the actual proportions.

[Electricity storage device]
FIG. 1 is a perspective view schematically showing a lithium ion secondary battery, which is an embodiment of a power storage device. FIG. 2 is a schematic cross-sectional view of the lithium ion secondary battery shown in FIG. 1 taken along line II-II. FIG. 3 is a partial sectional view schematically showing a portion of the laminate exterior material for a lithium ion secondary battery shown in FIG. 1, surrounded by line III.

As shown in FIGS. 1 to 3, the lithium ion secondary battery 1 of the present embodiment includes a battery element 10, which is an embodiment of a power storage element, and a laminate exterior material 20 that exteriorizes the battery element 10. . This lithium ion secondary battery 1 is constructed by sealing the inner layers 22, 22 of the laminate exterior material 20 along the periphery of the battery element 10 while leaving the positive electrode tab 11C and negative electrode tab 12C attached to the battery element 10 exposed to the outside. It has a fixed configuration. Note that such a laminate exterior material 20 may be formed into a bag shape as in the past, or may be formed into a container shape by molding using a molding die, and the battery element 10 may be placed inside the laminate exterior material 20. Encased and heat sealed.

The battery element 10 includes a positive electrode 11 having positive electrode active material layers 11B formed on both surfaces of a positive electrode current collector 11A, an electrolyte layer 13, and a negative electrode active material layer 12B formed on both surfaces of a negative electrode current collector 12A. It has a structure in which a plurality of negative electrodes 12 are stacked. At this time, a positive electrode active material layer 11B formed on one surface of the positive electrode current collector 11A of the one positive electrode 11 and one surface of the negative electrode current collector 12A of the negative electrode 12 adjacent to the one positive electrode 11 are formed. A plurality of positive electrodes, electrolyte layers, and negative electrodes are stacked in this order so that the negative electrode active material layers 12B face each other with the electrolyte layer 13 in between.

Thereby, the adjacent positive electrode active material layer 11B, electrolyte layer 13, and negative electrode active material layer 12B constitute one cell layer 14. Therefore, the lithium ion secondary battery 1 of this embodiment has a configuration in which a plurality of cell layers 14 are stacked and electrically connected in parallel. Note that the negative electrode active material layer 12B is formed only on one side of the negative electrode current collector 12a located at the outermost layer of the battery element 10. Moreover, an insulating layer (not shown) for insulating between adjacent positive electrode current collectors and negative electrode current collectors may be provided around the outer periphery of the unit cell layer.

The laminate exterior material 20 shown in FIG. 3 has an outer layer 21 forming the outer surface of the laminate exterior material 20 in the lithium ion secondary battery 1, an inner layer 22 forming the inner surface, and a barrier layer 23 disposed between them. These are laminated and integrated. Note that an adhesive layer 24 is provided between the barrier layer 23 and the outer layer 21 and between the barrier layer 23 and the inner layer 22 in order to firmly laminate and integrate them.

In the laminate exterior material 20 shown in FIG. 3, both the outer layer 21 and the inner layer 22 include a porous layer 25 having voids 25a.

4 to 6 are partial cross-sectional views schematically showing the same portions as in FIG. 3 of the first to third modified examples of the laminate exterior material shown in FIG. 3. FIG. 7 is a side view schematically showing the negative electrode tab side of the lithium ion secondary battery shown in FIG. In the following description, the same components as those described above will be given the same reference numerals, and detailed descriptions of the invention will be omitted.

In the laminate exterior material 20A shown in FIG. 4, the outer layer 21 of the outer layer 21 and the inner layer 22 includes a porous layer 25, and in the laminate exterior material 20B shown in FIG. Inner layer 22 includes porous layer 25 .

The laminate exterior material 20C shown in FIG. 6 further includes a protective layer 26 in addition to an outer layer 21 including a porous layer 25 having voids 25a, an inner layer 22 including a porous layer 25 having voids 25a, and a barrier layer 23. ing. In this way, in the laminate exterior material, each of the outer layer 21 and the inner layer 22 may have a multilayer structure. As shown in FIG. 6, adhesive layers 24 are also provided between the barrier layer 23 and the protective layer 26 and between the protective layer 26 and the inner layer 22 in order to firmly laminate and integrate them. .

Further, as shown in FIG. 7, both of the inner layers 22, 22 include the porous layer 25, and in the sealing area 20s on both sides of the negative electrode tab 12C by the inner layers 22, 22, the voids 25a of the porous layer 25 is crushed and deformed. Although not shown, the voids in the porous layer are also crushed and deformed in the sealing region of the positive electrode tab by the inner layer.

Next, advantages of this embodiment will be explained.
According to the present embodiment, at least one of the outer layer 21 and the inner layer 22 in the laminate exterior materials 20, 20A, 20B, and 20C includes the porous layer 25, so that volume expansion due to charging and discharging of a power storage device such as a lithium ion secondary battery is prevented. It has the advantage that it can absorb stress and reduce stress applied to electricity storage elements such as battery elements. Additionally, the outer layer and inner layer, which have a thickness to absorb volumetric expansion, have a secondary advantage of being excellent in scratch resistance. Furthermore, the configuration in which the inner layer includes a porous layer has the secondary advantage that, when the battery element contains an electrolyte, decomposed gas generated by decomposition of the electrolyte can be retained in the voids.

Moreover, in this embodiment, it is preferable that the porosity of the porous layer is 50 volume % or more and 80 volume % or less. If the porosity of the porous layer is less than 50% by volume, the compressibility may decrease and the cushion pad performance may decrease. On the other hand, if the porosity of the porous layer exceeds 80% by volume, the reaction force generated when it is compressed becomes weaker, and there is a possibility that the fixation of the battery element will deteriorate when external input is applied due to impact, etc. be.

Furthermore, according to the example shown in FIG. 7, and furthermore, FIG. 3, FIG. 5, and FIG. Since the voids 25a of the porous layer 25 are crushed and deformed in the sealing areas 20s on both sides of the laminate and the sealing area 20s on both sides of the positive electrode tab (not shown), the laminate exterior material 20 is in close contact with the negative electrode tab 12C and the positive electrode tab. For example, when the battery element contains an electrolyte, there is an advantage that the risk of electrolyte leakage can be reduced. Further, the configuration in which the voids 25a of the porous layer 25 are crushed and deformed has a secondary advantage that it can be formed without using a mold having a special shape.

[Assembled power storage device]
FIG. 8 is a partial cross-sectional view schematically showing a part of the assembled battery 50 of the lithium ion secondary battery 1, which is an embodiment of the assembled power storage device.

As shown in FIG. 8, the assembled battery 50 of the lithium ion secondary battery 1 has a plurality of flat lithium ion secondary batteries 1 arranged in the thickness direction of the lithium ion secondary battery 1 (indicated by arrow Z in FIG. 8). They are stacked in the horizontal direction (as shown). Note that the lithium ion secondary battery 1 is one to which the laminate exterior material 20A of the first modification described above is applied. Although not shown in FIG. 8, the lithium ion secondary battery 1 has battery elements 10 on the upper and lower sides of the battery element 10 in FIG. It has a structure in which the inner layers 22 of the laminate exterior material 20 are sealed together along the periphery of the laminate exterior material 10.

Next, advantages of this embodiment will be explained.
According to this embodiment, since the outer layer 21 of the laminate exterior material 20A includes the porous layer 25, it absorbs the volumetric expansion due to charging and discharging of a power storage device such as a lithium ion secondary battery, and absorbs volume expansion that is applied to a power storage element such as a battery element. This has the advantage that not only stress can be reduced, but also an efficient heat dissipation path can be formed between power storage devices such as lithium ion secondary batteries. Further, when assembling the assembled battery, there is no need to install other members having a cushion function or the like, so there is a secondary advantage that assembly costs can be reduced.

Here, the specifications and material types of each component will be explained in more detail.

(Positive electrode current collector)
The positive electrode current collector 11A is made of a conductive material such as aluminum foil, copper foil, or stainless steel (SUS) foil. However, the material is not limited to these, and conventionally known materials used as current collectors for lithium ion secondary batteries can be used.

(Positive electrode active material layer)
The positive electrode active material layer 12A contains a conventionally known positive electrode active material for lithium ion secondary batteries as a positive electrode active material, and may also contain a binder and a conductive aid as necessary.

As the positive electrode active material, for example, a lithium-containing compound is preferable from the viewpoint of capacity and output characteristics. Such lithium-containing compounds include, for example, composite oxides containing lithium and a transition metal element, phosphoric acid compounds containing lithium and a transition metal element, sulfuric acid compounds containing lithium and a transition metal element, lithium and a transition metal element, etc. Examples include solid solutions containing elements, but from the viewpoint of obtaining higher capacity and output characteristics, lithium-transition metal composite oxides are particularly preferred. In particular, it is possible to suitably use a high-potential positive electrode active material in which the electrolyte is easily decomposed at the end of charging at the positive electrode when charging and discharging a lithium ion secondary battery using an electrolyte. An example of such a high potential positive electrode active material is spinel type LiMn _1.5 Ni _0.5 O ₄ which is known as a 5V class positive electrode active material.

As the binder, conventionally known materials used as binders for lithium ion secondary batteries can be used. These binders may be used alone or in combination of two or more.

As the conductive aid, conventionally known materials used as conductive aids for lithium ion secondary batteries can be used. These conductive aids may be used alone or in combination of two or more.

(Positive electrode tab)
The positive electrode tab 11C is made of a material such as aluminum, copper, titanium, nickel, stainless steel (SUS), or an alloy thereof. However, the material is not limited to these, and conventionally known materials used as tabs for lithium ion secondary batteries can be used.

(Negative electrode current collector)
The negative electrode current collector 12A may be made of the same material as the above-described positive electrode current collector 11A, for example. Note that the negative electrode current collector may be made of the same material as the positive electrode current collector, or may be made of a different material.

(Negative electrode active material layer)
The negative electrode active material layer 12B contains, as a negative electrode active material, any one or two or more types of negative electrode materials capable of intercalating and deintercalating lithium, and may contain a binder and a conductive additive as necessary. It's okay to stay. Note that the binder and conductive aid described above can be used.

As the negative electrode material capable of intercalating and deintercalating lithium, conventionally known materials used as negative electrode materials for lithium ion secondary batteries can be used. In particular, as a negative electrode material having high capacity, a negative electrode material containing silicon can be suitably used. When a lithium ion secondary battery is charged and discharged, a silicon-containing negative electrode, a so-called silicon negative electrode, expands and contracts more severely than a conventional negative electrode using graphite, so the effect of applying the laminate exterior material of the present invention cannot be obtained. Cheap.

(Negative electrode tab)
For example, the negative electrode tab 12C may be made of the same material as the positive electrode tab 11C described above. Note that the negative electrode tab may be made of the same material as the positive electrode tab, or may be made of a different material.

(electrolyte layer)
As the electrolyte layer 13, conventionally known materials used as electrolyte layers for lithium ion secondary batteries can be used. For example, a layered structure is formed using an electrolytic solution held in a separator, a polymer gel electrolyte, or a solid polymer electrolyte, and a layered structure is formed using a polymer gel electrolyte or solid polymer electrolyte. etc. can be mentioned.

(insulating layer)
The insulating layer holds the electrolyte contained in the electrolyte layer 13 and the like, and is preferably formed around the outer periphery of the cell layer 14 using a material such as resin or rubber that prevents electrolyte from leaking.

(outer layer)
The outer layer 21 is also called a base material layer of the laminate exterior material, and as the outer layer, for example, a polyamide (nylon) film, a high-density polyethylene film, a polypropylene film, a polyethylene terephthalate film, etc. can be used. In particular, it is preferable to use a heat-resistant resin film such as a polyamide (nylon) film or a polyethylene terephthalate film as the outer layer. These may be used alone or in combination of two or more. The thickness of the outer layer is not limited and is usually 50 to 200 μm.

(inner layer)
The inner layer 22 preferably has excellent chemical resistance against highly corrosive electrolytes and the like, and also preferably provides heat sealability to the laminate exterior material. As the inner layer, for example, a polypropylene film such as an unstretched polypropylene film (CPP film), a polyethylene film such as a linear low density polyethylene film (LLDPE film), etc. can be used.

(barrier layer)
Barrier layer 23 is usually made of metal foil. As the metal foil, for example, aluminum (including its alloy) foil, copper (including its alloy) foil, nickel (including its alloy) foil, titanium (including its alloy) foil, stainless steel foil, etc. may be used. In particular, aluminum foil can be suitably used. Further, the metal foil may have a corrosion prevention treatment layer such as a chemical conversion coating formed on one or both sides thereof. The thickness of the barrier layer is not limited, and is usually 15 to 150 μm, preferably 15 to 40 μm. If the thickness of the barrier layer is less than 15 μm, deformation or cracks may occur during the manufacturing process, which will be described in detail later. On the other hand, when the thickness of the barrier layer exceeds 150 μm, it is not preferable from the viewpoints of material cost, flexibility, moldability, and weight increase.

(Adhesive layer)
The adhesive layer 24 is not limited as long as it is made of an adhesive that can bond the outer layer 21 (inner layer 22) and the barrier layer 23 together. For example, as such an adhesive, it is preferable to use a dry laminating adhesive such as a polyester adhesive, a polyester polyurethane adhesive, or an epoxy-containing polyester polyurethane adhesive. The adhesive layer is formed, for example, by applying an adhesive for the outer adhesive layer onto the barrier layer, which is a layer to be adhered to the outer layer, using a predetermined coating method. As a method for applying the adhesive for the adhesive layer, for example, a gravure coating method, a spray coating method, a doctor blade coating method, etc. can be used.

(porous layer)
Examples of the porous layer 25 include a porous polymer membrane, and its structure is not particularly limited. For example, the porous layer may have only independent pores, only communicating pores, or both independent pores and communicating pores. Among them, a porous layer has a three-dimensional network structure in which solids are spread three-dimensionally in a network, or a large number of spherical or approximately spherical solids are formed by directly or by decomposing linear solids. It is preferred to have a three-dimensional porous structure with connected spherical structures. Moreover, it may have both of these structures. The thickness of the porous layer is preferably 5 μm or more and 200 μm or less, more preferably 20 μm or more and 100 μm or less. If the thickness of the porous layer is less than 5 μm, the cushion pad performance may deteriorate, and the barrier layer may be easily damaged by external stress. On the other hand, when the thickness of the porous layer exceeds 200 μm, the energy volume density of the electricity storage device may decrease.

The porous layer as described above can be obtained by a conventionally known manufacturing method. For example, the porous layer can be obtained by a microporous film manufacturing method using a wet method as described in JP-A-55-131028. Specifically, the porous layer is formed using a process of forming a film using a mixture of resin such as polyethylene or polypropylene, which is a matrix resin that forms a microporous film, and adding additives to it, and a process of forming a film into a sheet. Later, by extracting the additive from a film made of the matrix resin and the additive, it can be obtained through a step of forming voids in the matrix resin. Examples of additives include solvents, plasticizers, and inorganic fine particles that are miscible with the resin. Further, for example, the porous layer can be obtained by a method for manufacturing a porous film using a dry method as described in Japanese Patent Publication No. 55-32531. Specifically, by employing a high draft ratio during melt extrusion, the lamellar structure in the film before being stretched is controlled, and by uniaxially stretching this, cleavage occurs at the lamellar interface and voids are eliminated. It can be obtained by forming Note that the method for forming the porous layer in the present invention is not limited to these methods. For example, it is also possible to use foamed plastic.

(protective layer)
As the protective layer 26, for example, a resin film such as a polyethylene terephthalate film, a polyamide (nylon) film, a polyethylene film, or a polypropylene film can be used, and a dense resin film without a porous structure is preferably used. I can do it. Thereby, the electrolyte resistance and scratch resistance of the barrier layer can be improved.

(Manufacturing method of laminate exterior material)
Here, a method for manufacturing a laminate exterior material will be described with reference to some examples.
First, a porous polypropylene film with a thickness of 100 μm as the outer layer 21, a porous polyethylene film with a thickness of 100 μm as the inner layer 22, and a metal foil (aluminum foil) with a thickness of 40 μm as the barrier layer 23 are prepared. Next, a chemical conversion film is formed on both sides of the aluminum foil. Specifically, a chemical conversion treatment containing phosphoric acid, polyacrylic acid (acrylic resin), chromium (III) salt compound, water, and alcohol is applied to both sides of aluminum foil, and dried at 180°C to form a chemical conversion film. Form. After that, a polyacrylic adhesive was applied to the surface of the chemical conversion coating on both sides of the aluminum foil to form an adhesive layer, and a porous polypropylene film with a thickness of 100 μm and a porous polyethylene film with a thickness of 100 μm were formed. By pasting them together, a laminate exterior material as shown in FIG. 3 is obtained.

Further, a porous polypropylene film with a thickness of 100 μm is prepared as the outer layer 21, a polyethylene film with a thickness of 50 μm as the inner layer 22, and a metal foil (aluminum foil) with a thickness of 40 μm as the barrier layer 23. Next, chemical conversion coatings are formed on both sides of the aluminum foil by operations similar to those described above. After that, a polyacrylic adhesive was applied to the surface of the chemical conversion coating on both sides of the aluminum foil to form an adhesive layer, and a porous polypropylene film with a thickness of 100 μm and a polyethylene film with a thickness of 50 μm were bonded together. Thus, a laminate exterior material as shown in FIG. 4 is obtained.

Furthermore, a polypropylene film with a thickness of 50 μm as the outer layer 21, a porous polyethylene film with a thickness of 100 μm as the inner layer 22, and a metal foil (aluminum foil) with a thickness of 40 μm as the barrier layer 23 are prepared. Next, chemical conversion coatings are formed on both sides of the aluminum foil by operations similar to those described above. After that, a polyacrylic adhesive was applied to the surface of the chemical conversion coating on both sides of the aluminum foil to form an adhesive layer, and a 50 μm thick polypropylene film and a 100 μm thick porous polyethylene film were bonded together. Thus, a laminate exterior material as shown in FIG. 5 is obtained.

In addition, the outer layer 21 is a porous polypropylene film with a thickness of 100 μm, the inner layer 22 is a porous polyethylene film with a thickness of 100 μm, the barrier layer 23 is a metal foil (aluminum foil) with a thickness of 40 μm, and the protective layer 26 is a porous polypropylene film with a thickness of 100 μm. A polyethylene terephthalate film with a thickness of 50 μm is prepared. Next, chemical conversion coatings are formed on both sides of the aluminum foil by operations similar to those described above. Furthermore, polyacrylic adhesive is applied to the surface of the chemical conversion coating on both sides of the aluminum foil to form an adhesive layer, and a porous polypropylene film with a thickness of 100 μm and a polyethylene terephthalate film with a thickness of 50 μm are bonded to each other. . Thereafter, a polyacrylic adhesive is applied to the surface of the polyethylene film to form an adhesive layer, and a porous polyethylene film having a thickness of 100 μm is bonded to obtain a laminate exterior material as shown in FIG.

Although the present invention has been described above with reference to some embodiments, the present invention is not limited to these embodiments, and various modifications can be made within the scope of the gist of the present invention.

In the present invention, in order to absorb the volume expansion due to charging and discharging of the power storage device and reduce the stress applied to the power storage element, a porous layer is provided in at least one of the outer layer and the inner layer of the laminate exterior material for the power storage device. The main point is to have established the following.

Therefore, the type of power storage device is not particularly limited as long as it can absorb the volumetric expansion due to charging and discharging of the power storage device and reduce the stress applied to the power storage element. For example, in each of the above-mentioned embodiments, a conventional power generation element in which a plurality of cell layers are stacked and electrically connected in parallel has been described, but a plurality of cell layers are stacked and electrically connected in series. It is also possible to have connected bipolar power generation elements. Further, for example, in each of the embodiments described above, a so-called laminated type power generation element is illustrated, but the electricity storage device of the present invention can also be applied to a so-called wound type power generation element including a laminated structure.

Furthermore, for example, in each of the above-described embodiments, a lithium ion secondary battery has been described as an example of the power storage device, but the power storage device may be an electric double layer capacitor such as a lithium ion capacitor, or an all-solid-state It may also be a battery.

Furthermore, for example, the above-mentioned components are not limited to the configurations shown in each embodiment, and the specifications and details of the material of the laminate exterior material may be changed, or the components of one example may be replaced with other examples. It is also possible to apply it in place of or in combination with the constituent elements. For example, in order to improve the adhesion between the laminate exterior material 20 and the negative electrode tab 12C or the positive electrode tab, at least one of the inner layers to be sealed may include a porous layer. Further, for example, when forming an efficient heat dissipation path between power storage devices such as lithium ion secondary batteries, at least one of the outer layers disposed facing each other between the power storage devices includes a porous layer. However, it is preferable that about 50% of the total outer layer contains a porous layer, and it is more preferable that all the outer layers contain a porous layer.

1 Lithium ion secondary battery (power storage device)
10 Battery element (electricity storage element)
11 Positive electrode 11A Positive electrode current collector 11B Positive electrode active material layer 11C Positive electrode tab 12, 12a Negative electrode 12A Negative electrode current collector 12B Negative electrode active material layer 12C Negative electrode tab 13 Electrolyte layer 14 Cell layer 20, 20A to 20C Laminate exterior material (power storage device laminate exterior material)
20s Sealing region 21 Outer layer 22 Inner layer 23 Barrier layer 24 Adhesive layer 25 Porous layer 25a Voids 26 Protective layer 30 Lithium ion secondary battery assembled battery (assembled electricity storage device)

Claims (6)

A laminate exterior material for a power storage device having an outer layer, an inner layer, and a barrier layer disposed between them,
A laminate exterior material for an electricity storage device, wherein at least one of the outer layer and the inner layer includes a porous layer. The laminate exterior material for an electricity storage device according to claim 1, wherein the porous layer has a porosity of 50% by volume or more and 80% by volume or less. A power storage device comprising: a power storage element having a positive electrode, a negative electrode, and an electrolyte; and a laminate exterior material for a power storage device that exteriorizes the power storage element and has an outer layer, an inner layer, and a barrier layer disposed between them;
An electricity storage device in which the inner layers of the laminate exterior material for an electricity storage device are sealed together along the periphery of the electricity storage element while the tabs of the positive electrode and the negative electrode are led outside,
An electricity storage device, wherein at least one of the outer layer and the inner layer includes a porous layer. At least one of the inner layers includes the porous layer,
4. The electricity storage device according to claim 3, wherein gaps in the porous layer are crushed and deformed in a region where the tabs of the positive electrode and/or the negative electrode are sealed by the inner layer. An assembled electricity storage device in which a plurality of flat-shaped electricity storage devices are stacked in the thickness direction of the electricity storage device,
The electricity storage device includes an electricity storage element having a positive electrode, a negative electrode, and an electrolyte, and a laminate exterior material for an electricity storage device that covers the electricity storage element and has an outer layer, an inner layer, and a barrier layer disposed between these,
The inner layers of the laminate exterior material for the power storage device are sealed together along the periphery of the power storage element while the tabs of the positive electrode and the negative electrode are led out to the outside,
An assembled electricity storage device, wherein at least one of the plurality of electricity storage devices is characterized in that at least one of the outer layer and the inner layer includes a porous layer. The assembled power storage device according to claim 5, wherein at least one of the outer layers disposed facing each other between the power storage devices includes the porous layer.

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