Laminate film for bipolar lithium-ion battery

Abstract

To provide a laminate film for a bipolar lithium-ion battery, which is excellent in electrolyte resistance and moldability.SOLUTION: A laminate film for a bipolar lithium-ion battery comprises at least a barrier layer, and a polyolefin layer that is provided on one side of the barrier layer. The polyolefin layer constitutes a surface on one side of the laminate film 10. The laminate film is arranged astride a ridge line part 20c from a principal plane 20a of an outer surface of the bipolar lithium-ion battery 20 to a side surface 20b thereof.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present disclosure relates to a laminated film for a bipolar lithium ion battery.

Background Art

[0002] As a power storage device that has been attracting attention in recent years, bipolar batteries are known. A bipolar battery uses a bipolar electrode having two electrodes on one current collector, with a positive electrode provided on one side of the current collector and a negative electrode provided on the other side, and an electrolyte is laminated between the positive electrode and the negative electrode of the bipolar electrode.

[0003] For example, the bipolar battery described in Patent Document 1 is an all-solid-state battery configured to include a unit cell of a lithium battery and a plurality of bipolar laminated batteries (cell stacks) each including an internal electrode layer laminated alternately with the unit cell. The plurality of laminated batteries are stacked via a positive electrode current collector foil and a negative electrode current collector foil and are connected in parallel to each other, and are sealed with a mold resin.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Nickel-metal hydride batteries are widely used as power storage devices for vehicles. In recent years, in order to achieve more space saving and higher output, nickel-metal hydride batteries with a bipolar structure are also used. Furthermore, it is conceivable to use a lithium ion battery with a bipolar structure that has a higher energy density than a nickel-metal hydride battery and can achieve higher output.

[0006] In the case of a nickel-metal hydride battery, since the electrolyte is aqueous, a high water vapor barrier property is not required, and the electrolyte can be enclosed in a plastic case such as polypropylene or polyethylene to form a battery. On the other hand, in a lithium-ion battery, since the electrolyte is an organic solvent system and hydrofluoric acid is generated when water enters the inside of the lithium-ion battery, it is necessary to cover the electrolyte with a film having a high barrier property.

[0007] Here, when covering a lithium-ion battery with a film, different from a nickel-metal hydride battery, electrolyte resistance is required. This is because a small amount of gas may flow out from the electrolyte inside the lithium-ion battery and come into contact with the film.

[0008] Also, when covering the outer surface of a lithium-ion battery with a film, it is effective to cover the positions where moisture easily enters. In the case of a bipolar lithium-ion battery, since moisture easily enters from the side surface part of the outer surface of the bipolar lithium-ion battery (electrodes (including end current collectors) are arranged on the main surfaces), it is desirable to cover with a film so as to straddle the ridge line part from the main surface to the side surface of the bipolar lithium-ion battery. Then, the film is required to have formability such as bending molding and drawing molding.

[0009] Under such circumstances, the main object of the present disclosure is to provide a laminated film for a bipolar lithium-ion battery, which is arranged on a part of the outer surface of the bipolar lithium-ion battery and has excellent electrolyte resistance and formability.

Means for Solving the Problems

[0010] The inventors of the present disclosure have conducted intensive studies to solve the above problems. As a result, a laminated film comprising at least a barrier layer and a polyolefin layer provided on one side of the barrier layer, wherein the polyolefin layer constitutes the surface on one side of the laminated film, and is arranged so as to straddle the ridge line portion from the main surface to the side surface of the outer surface of the bipolar lithium ion battery, has excellent electrolyte resistance and moldability, and is suitable as a laminated film disposed on a part of the outer surface of the bipolar lithium ion battery.

[0011] Based on such new findings, the present disclosure has been completed through further studies. That is, the present disclosure provides an invention in the following aspects. A laminated film disposed on a part of the outer surface of a bipolar lithium ion battery, wherein the laminated film comprises at least a barrier layer and a polyolefin layer provided on one side of the barrier layer, and the polyolefin layer constitutes the surface on one side of the laminated film, and the laminated film is arranged so as to straddle the ridge line portion from the main surface to the side surface of the outer surface of the bipolar lithium ion battery, a laminated film for a bipolar lithium ion battery.

Effect of the Invention

[0012] According to the present disclosure, there can be provided a laminated film for a bipolar lithium ion battery which is disposed on a part of the outer surface of the bipolar lithium ion battery and has excellent electrolyte resistance and moldability. Further, according to the present disclosure, there can also be provided an electric storage device using the laminated film.

Brief Description of the Drawings

[0013]

Figure 1

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Figure 10

Mode for Carrying Out the Invention

[0014] The laminated film for a bipolar lithium-ion battery of the present disclosure (hereinafter sometimes referred to as the laminated film of the present disclosure) is a laminated film disposed on a part of the outer surface of the bipolar lithium-ion battery. The laminated film of the present disclosure includes at least a barrier layer and a polyolefin layer provided on one side of the barrier layer. The polyolefin layer constitutes the surface on one side of the laminated film of the present disclosure. The laminated film of the present disclosure is disposed so as to straddle the ridge line portion from the main surface to the side surface of the outer surface of the bipolar lithium-ion battery. Since the laminated film of the present disclosure is excellent in formability, it can be suitably disposed so as to straddle the ridge line portion from the main surface to the side surface of the outer surface of the bipolar lithium-ion battery. Further, since the laminated film of the present disclosure is also excellent in electrolyte resistance, it is suitable as a laminated film disposed on a part of the outer surface of the bipolar lithium-ion battery.

[0015] Hereinafter, the laminated film of the present disclosure will be described in detail. In this specification, the numerical range indicated by "~" means "or more" and "or less". For example, the notation of 2~15 mm means 2 mm or more and 15 mm or less. For example, the notation of 2~15 mm means 2 mm or more and 15 mm or less. In the numerical ranges described step by step in the present disclosure, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the upper limit value or the lower limit value of the numerical range of other stepwise descriptions. Further, the upper limit value and the upper limit value, the upper limit value and the lower limit value, or the lower limit value and the lower limit value described separately may be combined to form a numerical range, respectively. Further, in the numerical ranges described in the present disclosure, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the value shown in the examples.

[0016] The laminated film 10 of the present disclosure includes at least a barrier layer and a polyolefin layer provided on one side of the barrier layer, and the polyolefin layer constitutes the surface on one side of the laminated film. For example, the laminated film 10 shown in FIG. 1 has a two-layer structure including a barrier layer 1 and a polyolefin layer 2 provided on one side of the barrier layer 1. Further, the laminated film 10 shown in FIG. 2 has a three-layer structure including a barrier layer 1, a polyolefin layer 2 provided on one side of the barrier layer 1, and a resin layer 3 provided on the other side of the barrier layer 1. An adhesive layer may exist between the barrier layer and the polyolefin layer 2 or the resin layer 3, or the barrier layer and the polyolefin layer 2 or the resin layer 3 may be in direct contact with each other. The laminated film 10 shown in FIG. 3 includes a barrier layer 1, a polyolefin layer 2 provided on one side of the barrier layer 1, and a resin layer 3 provided on the other side of the barrier layer 1, and has a four-layer structure in which an adhesive layer 4 is disposed between the barrier layer 1 and the polyolefin layer 2. The laminated film 10 shown in FIG. 4 includes a barrier layer 1, a polyolefin layer 2 provided on one side of the barrier layer 1, and a resin layer 3 provided on the other side of the barrier layer 1, an adhesive layer 4 is disposed between the barrier layer 1 and the polyolefin layer 2, and an adhesive layer 5 is disposed between the barrier layer 1 and the resin layer 3, having a five-layer structure.

[0017] The laminated film 10 of the present disclosure preferably has a two- to six-layer structure, more preferably a two- to five-layer structure, and even more preferably a three- to five-layer structure.

[0018] In the laminated film 10 of the present disclosure, the polyolefin layer 2 can be disposed on the outer surface side of the bipolar lithium ion battery 20 (that is, used such that the bipolar lithium ion battery is in contact with the polyolefin layer 2). When the laminated film 10 of the present disclosure includes the resin layer 3, the resin layer 3 can also be disposed on the outer surface side of the bipolar lithium ion battery 20 (that is, used such that the bipolar lithium ion battery 20 is in contact with the resin layer 3).

[0019] The shape of the laminated film 10 of the present disclosure is not particularly limited, and any shape can be used as long as it can be arranged so as to straddle the ridge line portion from the main surface to the side surface of the outer surface of the bipolar lithium ion battery.

[0020] For example, as shown in FIG. 5, the laminated film 10 of the present disclosure is made rectangular and arranged so as to straddle the ridge line portion 20c from the main surface 20a to the side surface 20b of the outer surface of the bipolar lithium ion battery 20 (that is, the laminated film 10 is bent at the position of the ridge line portion 20c). Thereby, the laminated film 10 of the present disclosure can protect the main surface 20a, the side surface 20b, and the ridge line portion 20c of the outer surface of the bipolar lithium ion battery 20.

[0021] Also, as shown in FIG. 6, a plurality of the laminated films 10 of the present disclosure (four laminated films 10a, 10b, 10c, and 10d are used in FIG. 6) may be arranged so as to straddle the ridge line portion 20c from the main surface 20a to the side surface 20b of the outer surface of the bipolar lithium ion battery 20. In FIG. 6, the adjacent laminated films do not overlap at the four corners of the bipolar lithium ion battery 20, but they may be arranged so that the adjacent laminated films overlap at the corners. In that case, the polyolefin layer on the outer surface of one laminated film and the polyolefin layer on the inner surface of the other laminated film can be heat-sealed at the overlapping portion.

[0022] Also, as shown in FIGS. 7, 8, and 9, the laminated film 10 of the present disclosure may cover a part of the main surface 20a, the entire side surface 20b, and the ridge line portion 20c. Thereby, while exposing the end collector 21 (electrode) located on the main surface 20a, the other parts of the outer surface of the bipolar lithium ion battery 20 can be protected by the laminated film 10 of the present disclosure. FIG. 8 illustrates a mode in which one drawn laminated film 10 and one non-formed laminated film 10 are applied to the outer surface of a bipolar lithium ion battery. FIG. 9 illustrates a mode in which two drawn laminated films 10 are applied to the outer surface of a bipolar lithium ion battery. By thermally fusing the polyolefin layers 2 of the two laminated films 10, the arrangement as shown in FIGS. 8 and 9 can be achieved.

[0023] Since the laminated film 10 of the present disclosure has excellent formability, the outer shape of the bipolar lithium ion battery to which the laminated film 10 is applied is not particularly limited, and examples include a rectangular parallelepiped shape (i.e., the main surface is rectangular in plan view) and a cylindrical shape (i.e., the main surface is circular in plan view). Note that the rectangular parallelepiped shape and the rectangular shape in plan view include not only a rectangular parallelepiped and a case where the corners of the rectangle are right angles, but also a rounded shape.

[0024] The thickness of the laminate constituting the laminated film 10 is not particularly limited. However, from the viewpoint of preferably exhibiting the effects of the present disclosure, for example, it may be about 210 μm or less, preferably about 190 μm or less, about 180 μm or less, about 155 μm or less, or about 120 μm or less. Further, from the viewpoint of maintaining the function of the laminated film of protecting the power storage device element, the thickness of the laminate constituting the laminated film 10 is preferably about 35 μm or more, about 45 μm or more, or about 60 μm or more. Further, regarding the preferable range of the laminate constituting the laminated film 10, for example, about 35 to 210 μm, about 35 to 190 μm, about 35 to 180 μm, about 35 to 155 μm, about 35 to 120 μm, about 45 to 210 μm, about 45 to 190 μm, about 45 to 180 μm, about 45 to 155 μm, about 45 to 120 μm, about 60 to 210 μm, about 60 to 190 μm, about 60 to 180 μm, about 60 to 155 μm, or about 60 to 120 μm can be mentioned. Particularly, when making the power storage device lightweight and thin, about 60 to 155 μm is preferable, and when improving the moldability, about 155 to 190 μm is preferable.

[0025] In the laminated film 10, the ratio of the total thickness of the barrier layer 1, the polyolefin layer 2, the resin layer 3 provided as necessary, and the adhesive layers 4 and 5 to the thickness (total thickness) of the laminate constituting the laminated film 10 is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more. As a specific example, when the laminated film 10 of the present disclosure includes the polyolefin layer 2, the barrier layer 1, and the resin layer 3, the ratio of the total thickness of these layers to the thickness (total thickness) of the laminate constituting the laminated film 10 is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more. Further, even when the laminated film 10 of the present disclosure includes the polyolefin layer 2, the adhesive layer 4, the barrier layer 1, and the resin layer 3, the ratio of the total thickness of these layers to the thickness (total thickness) of the laminate constituting the laminated film 10 can be, for example, 80% or more, preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more. Further, even when the laminated film 10 of the present disclosure includes the polyolefin layer 2, the adhesive layer 4, the barrier layer 1, the adhesive layer 5, and the resin layer 3, the ratio of the total thickness of these layers to the thickness (total thickness) of the laminate constituting the laminated film 10 can be, for example, 80% or more, preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more.

[0026] Hereinafter, each layer (barrier layer 1, polyolefin layer 2, resin layer 3 provided as necessary, adhesive layers 4 and 5 provided as necessary) constituting the laminated film 10 of the present disclosure will be described in detail.

[0027] [Barrier layer 1] In the laminated film 10 of the present disclosure, the barrier layer 1 is a layer that suppresses at least the intrusion of moisture.

[0028] Examples of the barrier layer 1 include a metal foil having barrier properties, a vapor deposition film, a resin layer, and the like. Examples of the vapor deposition film include a metal vapor deposition film, an inorganic oxide vapor deposition film, a carbon-containing inorganic oxide vapor deposition film, and the like. Examples of the resin layer include fluorine-containing resins such as polyvinylidene chloride, polymers mainly composed of chlorotrifluoroethylene (CTFE), polymers mainly composed of tetrafluoroethylene (TFE), polymers having a fluoroalkyl group, and polymers mainly composed of fluoroalkyl units, ethylene-vinyl alcohol copolymers, and the like. Further, examples of the barrier layer 1 include a resin film provided with at least one of these vapor deposition films and resin layers. A plurality of barrier layers 1 may be provided. The barrier layer 1 preferably includes a layer made of a metal material. Specific examples of the metal material constituting the barrier layer 1 include aluminum alloy, stainless steel, titanium steel, steel plate, and the like. When used as a metal foil, it preferably includes at least one of an aluminum alloy foil and a stainless steel foil.

[0029] From the perspective of improving the formability of the laminated film, the aluminum alloy foil is more preferably a soft aluminum alloy foil composed of, for example, an annealed aluminum alloy or the like, and from the perspective of further improving the formability, it is preferably an aluminum alloy foil containing iron. In the aluminum alloy foil containing iron (100% by mass), the iron content is preferably about 0.1% by mass or more, more preferably about 0.5% by mass or more, still more preferably about 0.7% by mass or more, still more preferably about 0.9% by mass or more, and still more preferably about 1.2% by mass or less. Also, it is preferably about 9.0% by mass or less, more preferably about 2.0% by mass or less, still more preferably about 1.7% by mass or less, and preferably about 1.3% by mass or less. Preferred ranges include about 0.1 to 9.0% by mass, about 0.1 to 2.0% by mass, about 0.1 to 1.7% by mass, about 0.1 to 1.3% by mass, about 0.5 to 9.0% by mass, about 0.5 to 2.0% by mass, about 0.5 to 1.7% by mass, about 0.5 to 1.3% by mass, about 0.7 to 9.0% by mass, about 0.7 to 2.0% by mass, about 0.7 to 1.7% by mass, about 0.7 to 1.3% by mass, about 0.9 to 9.0% by mass, about 0.9 to 2.0% by mass, about 0.9 to 1.7% by mass, about 0.9 to 1.3% by mass, about 1.2 to 9.0% by mass, about 1.2 to 2.0% by mass, about 1.2 to 1.7% by mass, and about 1.2 to 1.3% by mass. When the iron content is 0.1% by mass or more, a laminated film with more excellent formability can be obtained. When the iron content is 9.0% by mass or less, a laminated film with more excellent flexibility can be obtained. Examples of the soft aluminum alloy foil include aluminum alloy foils having a composition defined by JIS H4160:1994 A8021H-O, JIS H4160:1994 A8079H-O, JIS H4000:2014 A8021P-O, or JIS H4000:2014 A8079P-O. Also, if necessary, silicon, magnesium, copper, manganese, etc. may be added. Softening can be performed by annealing or the like.

[0030] The chemical composition of JIS A8021 is specified in the JIS standard (JIS H4160:2006) as follows: Si is 0.15 mass% or less, Fe is 1.2 - 1.7 mass% or less, Cu is 0.05 mass% or less, other elements other than Al are each 0.05 mass% or less, and the total of these other elements is 0.15 mass% or less, with the balance being Al. Conventionally, the Si content in aluminum alloy foils that meet the chemical composition of JIS A8021 has usually been at least 0.10 mass% or more, and those below this have not been substantially used. Even for aluminum alloy foils used in energy storage devices, those with 0.10 mass% or more have been used. On the other hand, among aluminum alloy foils that meet the chemical composition of JIS A8021, by using an aluminum alloy foil with an extremely low Si content of 0.08 mass% or less as a battery packaging material, the formability of a laminate of different materials, such as at least a laminate of an aluminum alloy foil and a polyolefin layer or a resin layer, is particularly excellent.

[0031] From the perspective of further improving the formability of the laminated film 10, the upper limit of the Si content in the aluminum alloy foil is preferably about 0.07 mass% or less, more preferably about 0.06 mass% or less, and the lower limit is, for example, about 0.02 mass% or more, preferably about 0.03 mass% or more, more preferably about 0.05 mass% or more. Also, the preferred range of the Si content in the aluminum alloy foil includes about 0.02 - 0.08 mass%, about 0.03 - 0.08 mass%, about 0.05 - 0.08 mass%, about 0.02 - 0.07 mass%, about 0.03 - 0.07 mass%, about 0.05 - 0.07 mass%, about 0.02 - 0.06 mass%, about 0.03 - 0.06 mass%, about 0.05 - 0.06 mass%.

[0032] From the perspective of further improving the formability of the laminated film 10, the upper limit of the Cu content in the aluminum alloy foil is preferably about 0.05% by mass or less, more preferably about 0.04% by mass or less, and the lower limit is, for example, 0.01% by mass or more, preferably about 0.02% by mass or more, more preferably about 0.03% by mass or more. Also, the preferable range of the Cu content in the aluminum alloy foil is about 0.01 to 0.05% by mass, about 0.01 to 0.04% by mass, about 0.02 to 0.05% by mass, about 0.02 to 0.04% by mass, about 0.03 to 0.05% by mass, about 0.03 to 0.04% by mass.

[0033] From the perspective of further improving the formability of the laminated film 10, the upper limit of the Fe content in the aluminum alloy foil is preferably about 1.58% by mass or less, more preferably about 1.56% by mass or less, and the lower limit is preferably about 1.44% by mass or more, more preferably about 1.46% by mass or more. Also, the preferable range of the Fe content in the aluminum alloy foil is about 1.44 to 1.58% by mass, about 1.44 to 1.56% by mass, about 1.46 to 1.58% by mass, about 1.46 to 1.56% by mass.

[0034] From the perspective of further enhancing the formability of the laminated film 10, for the average crystal grain size of the aluminum alloy foil, the upper limit is preferably about 10.0 μm or less, more preferably 5.0 μm or less, still more preferably 3.0 μm or less, and the lower limit is preferably about 1.0 μm or more, more preferably about 3.0 μm or more. The preferable range is about 1.0 to 10.0 μm, about 1.0 to 7.0 μm, about 1.0 to 5.0 μm, about 1.0 to 3.0 μm, about 3.0 to 10.0 μm, about 3.0 to 7.0 μm, about 3.0 to 5.0 μm.

[0035] From the perspective of further improving the formability of the laminated film 10, the upper limit of the standard deviation of the average crystal grain size of the aluminum alloy foil is preferably about 6 μm or less, more preferably 5 μm or less, and still more preferably 4 μm or less. The lower limit is preferably about 1 μm or more, more preferably about 2 μm or more. Preferred ranges include about 1 to 6 μm, about 1 to 5 μm, about 1 to 4 μm, about 2 to 6 μm, about 2 to 5 μm, and about 2 to 4 μm. The standard deviation of the average crystal grain size of the aluminum alloy foil is calculated from the grain sizes of 100 aluminum alloy crystal grains actually measured by the following cross-sectional observation.

[0036] In the present disclosure, the average crystal grain size in the aluminum alloy foil is observed by a scanning electron microscope (SEM) for the cross-section in the thickness direction of the aluminum alloy foil. For 100 aluminum alloy crystal grains located within the field of view, when the straight-line distance connecting one point on the epitaxy of the crystal grain and another point on the epitaxy of the same crystal grain is the maximum diameter x, it means the average value of the maximum diameter x of the 100 crystal grains.

[0037] Also, in the present disclosure, in the cross-section in the thickness direction of the laminate constituting the laminated film 10, for any 100 second-phase particles within the field of view where the aluminum alloy foil is observed with an optical microscope, the average of the diameters y of the top 20 second-phase particles in descending order of the diameter y, which is the straight-line distance connecting one point on the epitaxy of the second-phase particle and another point on the epitaxy of the same second-phase particle and is the maximum, is preferably about 5.0 μm or less, more preferably about 1.0 to 4.0 μm, and still more preferably about 1.0 to 2.0 μm. When the average crystal grain size in the aluminum alloy foil is 10.0 μm or less and the diameter of the second-phase particle is within such a range, the formability of the laminated film 10 can be further improved.

[0038] In the present disclosure, the second-phase particles contained in the aluminum alloy foil form intermetallic compounds such as Al-(Fe·Mn)-Si, and mainly such second-phase particles generated during solidification in the casting process remain without being immobilized in the subsequent process.

[0039] When observing the cross-section of an aluminum alloy foil in the thickness direction with a scanning electron microscope (SEM), crystal grains usually depict a boundary line that contacts multiple crystals. In contrast, second-phase particles usually have a boundary line that is a single crystal. Also, since the crystal grains and the second-phase particles have different phases, they have different colors on the SEM image, and the second-phase particles often appear white. Furthermore, when observing the cross-section of an aluminum alloy foil in the thickness direction with an optical microscope, only the second-phase particles appear black due to the phase difference between the crystal grains and the second-phase particles, making the observation easier.

[0040] Also, from the perspective of further enhancing the formability of the aluminum alloy foil, in the cross-section in the thickness direction of the laminate constituting the laminated film 10, the area average of the particles of the aluminum alloy foil preferably has an upper limit of about 40 μm 2 More preferably, 30 μm or less 2 Even more preferably, 25 μm or less 2 The following can be mentioned. For the lower limit, preferably about 4 μm 2 Or more, more preferably about 5 μm 2 The following can be mentioned. The preferable range is 4 - 40 μm 2 Or so, 4 - 30 μm 2 Or so, 4 - 25 μm 2 Or so, 5 - 40 μm 2 Or so, 5 - 30 μm 2 Or so, 5 - 25 μm 2 Or so can be mentioned. The area average of the particles is measured as follows.

[0041] <Measurement of the area average of particles> The average crystal area of the particles is observed using EBSD (electron backscatter diffraction method, for example, DVC5 manufactured by TSL Solutions) of a scanning electron microscope (SEM) on the cross-section of the aluminum alloy foil at an acceleration voltage of 15 kV, a working distance of 15 mm, an inclination angle of 70 degrees, and a magnification of 2000 times, and calculated using the accompanying analysis software.

[0042] Examples of the stainless steel foil include austenitic, ferritic, austenitic-ferritic, martensitic, and precipitation-hardening stainless steel foils. Further, from the viewpoint of providing a laminated film with excellent formability, the stainless steel foil is preferably composed of an austenitic stainless steel.

[0043] Specific examples of the austenitic stainless steel constituting the stainless steel foil include SUS304, SUS301, SUS316L, etc. Among these, SUS304 is particularly preferable.

[0044] In the case of a metal foil, the thickness of the barrier layer 1 only needs to exhibit a function as a barrier layer that at least suppresses the ingress of moisture, and for example, it can be about 9 to 200 μm. The thickness of the barrier layer 1 is preferably about 85 μm or less, more preferably about 50 μm or less, still more preferably about 40 μm or less, and particularly preferably about 35 μm or less. Also, the thickness of the barrier layer 1 is preferably about 10 μm or more, still more preferably about 20 μm or more, and more preferably about 25 μm or more. Further, the preferred range of the thickness of the barrier layer 1 includes about 10 to 85 μm, about 10 to 50 μm, about 10 to 40 μm, about 10 to 35 μm, about 20 to 85 μm, about 20 to 50 μm, about 20 to 40 μm, about 20 to 35 μm, about 25 to 85 μm, about 25 to 50 μm, about 25 to 40 μm, and about 25 to 35 μm. When the barrier layer 1 is composed of an aluminum alloy foil, the above-mentioned range is particularly preferred. Also, from the viewpoint of imparting high formability and high rigidity to the laminated film 10, the thickness of the barrier layer 1 is preferably about 35 μm or more, more preferably about 45 μm or more, still more preferably about 50 μm or more, and even more preferably about 55 μm or more. Also, it is preferably about 200 μm or less, more preferably about 85 μm or less, still more preferably about 75 μm or less, and even more preferably about 70 μm or less. The preferred range includes about 35 to 200 μm, about 35 to 85 μm, about 35 to 75 μm, about 35 to 70 μm, about 45 to 200 μm, about 45 to 85 μm, about 45 to 75 μm, about 45 to 70 μm, about 50 to 200 μm, about 50 to 85 μm, about 50 to 75 μm, about 50 to 70 μm, about 55 to 200 μm, about 55 to 85 μm, about 55 to 75 μm, and about 55 to 70 μm. Since the laminated film 10 has high formability, deep drawing forming becomes easy, which can contribute to increasing the capacity of the power storage device. Also, when the capacity of the power storage device is increased, the weight of the power storage device increases, but by increasing the rigidity of the laminated film 10, it can contribute to the high sealing performance of the power storage device. In particular, when the barrier layer 1 is composed of a stainless steel foil, the thickness of the stainless steel foil is preferably about 60 μm or less, more preferably about 50 μm or less, still more preferably about 40 μm or less, even more preferably about 30 μm or less, and particularly preferably about 25 μm or less.Also, the thickness of the stainless steel foil is preferably about 10 μm or more, more preferably about 15 μm or more. Also, the preferable range of the thickness of the stainless steel foil includes about 10 to 60 μm, about 10 to 50 μm, about 10 to 40 μm, about 10 to 30 μm, about 10 to 25 μm, about 15 to 60 μm, about 15 to 50 μm, about 15 to 40 μm, about 15 to 30 μm, about 15 to 25 μm.

[0045] Also, when the barrier layer 1 is a metal foil, it is preferable that at least one surface is provided with a corrosion-resistant film for preventing dissolution and corrosion. The barrier layer 1 may be provided with corrosion-resistant films on both surfaces. Here, the corrosion-resistant film means, for example, a hot water conversion treatment such as boehmite treatment, chemical conversion treatment, anodizing treatment, plating treatment such as nickel or chromium, or a corrosion prevention treatment of applying a coating agent to the surface of the barrier layer to provide the barrier layer with corrosion resistance (e.g., acid resistance, alkali resistance, etc.). Specifically, the corrosion-resistant film means a film that improves the acid resistance of the barrier layer (acid-resistant film), a film that improves the alkali resistance of the barrier layer (alkali-resistant film), and the like. As the treatment for forming the corrosion-resistant film, one type may be performed, or two or more types may be combined. Also, it can be made into multiple layers instead of just one layer. Furthermore, among these treatments, the hot water conversion treatment and the anodizing treatment are treatments that dissolve the metal foil surface with a treatment agent and form a metal compound with excellent corrosion resistance. Note that these treatments may be included in the definition of the chemical conversion treatment. Also, when the barrier layer 1 is provided with a corrosion-resistant film, the barrier layer 1 including the corrosion-resistant film is used.

[0046] The corrosion-resistant film prevents delamination between the barrier layer 1 (e.g., aluminum alloy foil) and the polyolefin layer 2 during the molding of the laminated film, and prevents dissolution and corrosion of the surface of the barrier layer 1 due to hydrogen fluoride generated by the reaction of the electrolyte and moisture. In particular, when the barrier layer 1 is an aluminum alloy foil, it prevents dissolution and corrosion of aluminum oxide present on the surface of the barrier layer. It also improves the adhesiveness (wettability) of the surface of the barrier layer 1, and shows the effect of preventing delamination between the polyolefin layer 2 and the barrier layer 1 during heat sealing and preventing delamination between the polyolefin layer 2 and the barrier layer 1 during molding.

[0047] As the corrosion-resistant film formed by chemical conversion treatment, various ones are known, and mainly include a corrosion-resistant film containing at least one of phosphates, chromates, fluorides, triazine thiol compounds, and rare earth oxides. Examples of the chemical conversion treatment using phosphates and chromates include chromic acid chromate treatment, phosphoric acid chromate treatment, phosphoric acid-chromate treatment, chromate treatment, etc. Examples of the chromium compounds used in these treatments include chromium nitrate, chromium fluoride, chromium sulfate, chromium acetate, chromium oxalate, dichromic acid chromium, acetylacetate chromium, chromium chloride, potassium sulfate chromium, etc. Examples of the phosphorus compounds used in these treatments include sodium phosphate, potassium phosphate, ammonium phosphate, polyphosphoric acid, etc. Examples of chromate treatment include etching chromate treatment, electrolytic chromate treatment, coating type chromate treatment, etc., and coating type chromate treatment is preferred. This coating type chromate treatment is a process in which at least the inner layer side surface of the barrier layer (for example, aluminum alloy foil) is first degreased by a well-known treatment method such as an alkali immersion method, an electrolytic cleaning method, an acid cleaning method, an electrolytic acid cleaning method, an acid activation method, etc., and then a treatment liquid mainly composed of a metal phosphate such as chromium (Cr) phosphate, titanium (Ti) phosphate, zirconium (Zr) phosphate, zinc (Zn) phosphate, etc. and a mixture of these metal salts, or a treatment liquid mainly composed of a non-metal phosphate and a mixture of these non-metal salts, or a treatment liquid composed of a mixture of these and a synthetic resin, etc. is applied by a well-known coating method such as a roll coating method, a gravure printing method, an immersion method, etc. and dried. As the treatment liquid, various solvents such as water, alcohol solvents, hydrocarbon solvents, ketone solvents, ester solvents, ether solvents, etc. can be used, and water is preferred. Examples of the resin component used at this time include polymers such as phenolic resins and acrylic resins, and chromate treatment using an aminophenol polymer having repeating units represented by the following general formulas (1) to (4) can be mentioned. In the aminophenol polymer, the repeating units represented by the following general formulas (1) to (4) may be contained alone or in any combination of two or more types.The acrylic resin is preferably a derivative such as polyacrylic acid, an acrylic acid-methacrylic acid ester copolymer, an acrylic acid-maleic acid copolymer, an acrylic acid-styrene copolymer, or their sodium salts, ammonium salts, amine salts, etc. In particular, derivatives of polyacrylic acid such as ammonium salts, sodium salts, or amine salts of polyacrylic acid are preferred. In the present disclosure, polyacrylic acid means a polymer of acrylic acid. Further, the acrylic resin is also preferably a copolymer of acrylic acid and a dicarboxylic acid or dicarboxylic anhydride, and is also preferably an ammonium salt, sodium salt, or amine salt of a copolymer of acrylic acid and a dicarboxylic acid or dicarboxylic anhydride. The acrylic resin may be used alone or in combination of two or more.

[0048]

Chemical formula

[0049]

Chemical formula

[0050]

Chemical formula

[0051]

Chemical formula

[0052] In general formulas (1) to (4), X represents a hydrogen atom, a hydroxy group, an alkyl group, a hydroxyalkyl group, an allyl group or a benzyl group. Also, R 1 and R 2 each independently represent a hydroxy group, an alkyl group, or a hydroxyalkyl group. In general formulas (1) to (4), X, R 1 and R 2Examples of the alkyl group represented by [alkyl group] include linear or branched alkyl groups having 1 to 4 carbon atoms such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, and tert-butyl group. Further, X, R 1 and R 2 Examples of the hydroxyalkyl group represented by [hydroxyalkyl group] include linear or branched alkyl groups having 1 to 4 carbon atoms with one hydroxy group substituted, such as hydroxymethyl group, 1-hydroxyethyl group, 2-hydroxyethyl group, 1-hydroxypropyl group, 2-hydroxypropyl group, 3-hydroxypropyl group, 1-hydroxybutyl group, 2-hydroxybutyl group, 3-hydroxybutyl group, and 4-hydroxybutyl group. In General Formulas (1) to (4), the alkyl groups and hydroxyalkyl groups represented by X, R 1 and R 2 may be the same or different from each other. In General Formulas (1) to (4), X is preferably a hydrogen atom, a hydroxy group, or a hydroxyalkyl group. The number average molecular weight of the aminated phenol polymer having the repeating unit represented by General Formulas (1) to (4) is preferably about 500 to 1,000,000, more preferably about 1,000 to 20,000. The aminated phenol polymer is produced, for example, by polycondensing a phenol compound or a naphthol compound and formaldehyde to produce a polymer composed of the repeating unit represented by the above General Formula (1) or General Formula (3), and then introducing the functional group (-CH2NR 1 R 2 ) into the polymer obtained above using formaldehyde and an amine (R 1 R 2 ). The aminated phenol polymer is used alone or in admixture of two or more.

[0053] As another example of the corrosion-resistant film, there is a thin film formed by a coating-type corrosion prevention treatment in which a coating agent containing at least one selected from the group consisting of rare earth element oxide sols, anionic polymers, and cationic polymers is applied. The coating agent may further contain phosphoric acid or a phosphate and a crosslinking agent for crosslinking the polymer. In the rare earth element oxide sol, fine particles of a rare earth element oxide (for example, particles having an average particle diameter of 100 nm or less) are dispersed in a liquid dispersion medium. Examples of the rare earth element oxide include cerium oxide, yttrium oxide, neodymium oxide, lanthanum oxide, etc., and cerium oxide is preferable from the viewpoint of further improving the adhesion. The rare earth element oxide contained in the corrosion-resistant film can be used alone or in combination of two or more. As the liquid dispersion medium of the rare earth element oxide sol, various solvents such as water, alcohol-based solvents, hydrocarbon-based solvents, ketone-based solvents, ester-based solvents, and ether-based solvents can be used, and water is preferable. Examples of the cationic polymer include polyethyleneimine, an ion polymer complex composed of polyethyleneimine and a polymer having a carboxylic acid, a primary amine graft acrylic resin obtained by graft polymerizing a primary amine onto an acrylic main skeleton, polyallylamine or its derivative, and aminated phenol. Further, as the anionic polymer, poly(meth)acrylic acid or its salt, or a copolymer having (meth)acrylic acid or its salt as a main component is preferable. Further, it is preferable that the crosslinking agent is at least one selected from the group consisting of a compound having any one of functional groups such as an isocyanate group, a glycidyl group, a carboxyl group, and an oxazoline group and a silane coupling agent. Further, it is preferable that the phosphoric acid or the phosphate is condensed phosphoric acid or condensed phosphate.

[0054] As an example of the corrosion-resistant film, there is one formed by applying, to the surface of a barrier layer, a material in which fine particles of metal oxides such as aluminum oxide, titanium oxide, cerium oxide, and tin oxide and barium sulfate are dispersed in phosphoric acid, and performing a baking treatment at 150 °C or higher.

[0055] The corrosion-resistant film may, if necessary, have a laminated structure in which at least one of a cationic polymer and an anionic polymer is further laminated. Examples of the cationic polymer and the anionic polymer include those described above.

[0056] In addition, the analysis of the composition of the corrosion-resistant film can be performed, for example, using time-of-flight secondary ion mass spectrometry.

[0057] The amount of the corrosion-resistant film formed on the surface of the barrier layer 1 in the chemical conversion treatment is not particularly limited. For example, in the case of performing a coating type chromate treatment, per 1 m 2 of the surface of the barrier layer 1, it is desirable that the chromic acid compound be contained in an amount of, for example, about 0.5 to 50 mg in terms of chromium, preferably about 1.0 to 40 mg; the phosphorus compound be contained in an amount of, for example, about 0.5 to 50 mg in terms of phosphorus, preferably about 1.0 to 40 mg; and the aminated phenol polymer be contained in an amount of, for example, about 1.0 to 200 mg, preferably about 5.0 to 150 mg.

[0058] The thickness of the corrosion-resistant film is not particularly limited. From the viewpoints of the cohesion of the film and the adhesion to the barrier layer and the polyolefin layer, it is preferably about 1 nm to 20 μm, more preferably about 1 nm to 100 nm, and still more preferably about 1 nm to 50 nm. The thickness of the corrosion-resistant film can be measured by observation with a transmission electron microscope or a combination of observation with a transmission electron microscope and energy dispersive X-ray spectroscopy or electron energy loss spectroscopy. By analyzing the composition of the corrosion-resistant film using time-of-flight secondary ion mass spectrometry, for example, peaks derived from secondary ions composed of Ce, P, and O (for example, at least one of Ce2PO4 + and CePO4 - ), and secondary ions composed of, for example, Cr, P, and O (for example, at least one of CrPO2 + and CrPO4 - ) are detected.

[0059] The chemical conversion treatment is carried out by applying a solution containing a compound used for forming a corrosion-resistant film onto the surface of the barrier layer by means such as a bar coating method, a roll coating method, a gravure coating method, or an immersion method, and then heating the barrier layer so that its temperature reaches about 70 to 200 °C. Further, before performing the chemical conversion treatment on the barrier layer, the barrier layer may be preliminarily subjected to a degreasing treatment by means such as an alkali immersion method, an electrolytic cleaning method, an acid cleaning method, or an electrolytic acid cleaning method. By performing the degreasing treatment in this way, it becomes possible to perform the chemical conversion treatment on the surface of the barrier layer more efficiently. Further, by using an acid degreasing agent in which a fluorine-containing compound is dissolved in an inorganic acid for the degreasing treatment, it is possible to form not only a degreasing effect on the metal foil but also a fluoride of a passive metal. In such a case, only the degreasing treatment may be performed.

[0060] [Polyolefin layer 2] In the laminated film 10 of the present disclosure, the polyolefin layer 2 is provided on one side of the barrier layer 1 and constitutes one surface of the laminated film 10. As described above, the laminated film 10 of the present disclosure can be used, for example, such that the polyolefin layer 2 is on the outer surface side of the bipolar lithium-ion battery 20. The polyolefin layer 2 preferably has heat-sealing properties. Since the polyolefin layer 2 has heat-sealing properties, the polyolefin layer 2 of the laminated film 10 of the present disclosure can be fixed to the outer surface of the bipolar lithium-ion battery 20 by heat sealing.

[0061] The resin constituting the polyolefin layer 2 is not particularly limited as long as it is a layer containing a polyolefin-based resin. The polyolefin-based resin is a resin containing a polyolefin backbone such as polyolefin or acid-modified polyolefin. The fact that the polyolefin layer 2 contains a polyolefin backbone can be analyzed, for example, by infrared spectroscopy, gas chromatography-mass spectrometry, or the like. Further, when the resin constituting the polyolefin layer 2 is analyzed by infrared spectroscopy, it is also preferable that a peak derived from maleic anhydride is detected. For example, when maleic anhydride-modified polyolefin is measured by infrared spectroscopy, the wavenumbers are 1760 cm -1 in the vicinity and 1780 cm-1 A peak derived from maleic anhydride is detected in the vicinity. When the polyolefin layer 2 is a layer composed of maleic anhydride-modified polyolefin, a peak derived from maleic anhydride is detected by infrared spectroscopy. However, if the degree of acid modification is low, the peak may become small and undetectable. In that case, it can be analyzed by nuclear magnetic resonance spectroscopy.

[0062] The polyolefin layer 2 preferably contains a polyolefin resin (a resin containing a polyolefin backbone) as a main component, more preferably contains a polyolefin as a main component, and even more preferably contains polypropylene or polyethylene as a main component. Here, the main component means that among the resin components contained in the polyolefin layer 2, the content rate is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 99% by mass or more of the resin component. For example, when the polyolefin layer 2 contains polypropylene as a main component, it means that among the resin components contained in the polyolefin layer 2, the content rate of polypropylene is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 99% by mass or more.

[0063] Examples of polyolefins include, specifically, polyethylene such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; ethylene-α-olefin copolymers; polypropylene such as homopolypropylene, block copolymers of polypropylene (e.g., block copolymers of propylene and ethylene), random copolymers of polypropylene (e.g., random copolymers of propylene and ethylene); propylene-α-olefin copolymers; and terpolymers of ethylene-butene-propylene. Among these, polypropylene is preferred. When it is a copolymer, the polyolefin resin may be a block copolymer or a random copolymer. These polyolefin-based resins may be used alone or in combination of two or more.

[0064] In addition, the polyolefin may be a cyclic polyolefin. A cyclic polyolefin is a copolymer of an olefin and a cyclic monomer. Examples of the olefin that is a constituent monomer of the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, styrene, butadiene, and isoprene. Examples of the cyclic monomer that is a constituent monomer of the cyclic polyolefin include cyclic alkenes such as norbornene; and cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, and norbornadiene. Among these, cyclic alkenes are preferred, and norbornene is more preferred.

[0065] In addition, the polyolefin may be an acid-modified polyolefin. An acid-modified polyolefin is a polymer obtained by modifying a polyolefin by block polymerization or graft polymerization with an acid component. As the polyolefin to be acid-modified, the above-mentioned polyolefins, copolymers obtained by copolymerizing the above-mentioned polyolefins with polar molecules such as acrylic acid or methacrylic acid, or polymers such as crosslinked polyolefins can also be used. Examples of the acid component used for acid modification include carboxylic acids or their anhydrides such as maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, and itaconic anhydride.

[0066] The acid-modified polyolefin may be an acid-modified cyclic polyolefin. The acid-modified cyclic polyolefin is a polymer obtained by copolymerizing a part of the monomers constituting the cyclic polyolefin by replacing it with an acid component, or by block polymerization or graft polymerization of an acid component onto the cyclic polyolefin. The cyclic polyolefin to be acid-modified is the same as described above. Also, the acid component used for acid modification is the same as the acid component used for the modification of the above polyolefin.

[0067] Preferred acid-modified polyolefins include polyolefins modified with carboxylic acid or its anhydride, polypropylene modified with carboxylic acid or its anhydride, maleic anhydride-modified polyolefin, and maleic anhydride-modified polypropylene.

[0068] The polyolefin layer 2 may be formed of a single resin alone, or may be formed of a blend polymer combining two or more resins. Further, the polyolefin layer 2 may be formed of only one layer, but may also be formed of two or more layers with the same or different resins.

[0069] When manufacturing the laminated film 10 of the present disclosure by laminating the polyolefin layer 2 with the barrier layer 1, a pre-formed resin film may be used as the polyolefin layer 2. Also, the heat-sealable resin forming the polyolefin layer 2 may be formed into a film on the surface of the barrier layer 1 or the like by extrusion molding, coating, etc., to form the polyolefin layer 2 formed of a resin film.

[0070] The melting point of the polyolefin layer is preferably about 120 °C or higher, more preferably about 125 °C or higher, still more preferably 130 °C or higher, and is also preferably about 170 °C or lower, more preferably about 165 °C or lower, still more preferably 160 °C or lower. Preferred ranges include about 120 to 170 °C and about 130 to 160 °C. In the present disclosure, the melting point is the melting peak temperature measured by a differential scanning calorimeter (DSC).

[0071] Further, the polyolefin layer 2 may contain a lubricant or the like as necessary. When the polyolefin layer 2 contains a lubricant, the moldability of the laminated film can be improved. The lubricant is not particularly limited, and known lubricants can be used.

[0072] The lubricant is not particularly limited, but preferably includes amide-based lubricants. Specific examples of the lubricant include those exemplified in the resin layer 3. The lubricant may be used alone or in combination of two or more, and it is preferable to use a combination of two or more.

[0073] In the present disclosure, from the viewpoint of enhancing the moldability of the laminated film, it is preferable that a lubricant is present on at least one of the surface and the interior of the polyolefin layer 2. The lubricant is not particularly limited, but preferably an amide-based lubricant. Specific examples of the amide-based lubricant include, for example, saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylol amides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid ester amides, aromatic bisamides, and the like. Specific examples of the saturated fatty acid amides include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, hydroxystearic acid amide, and the like. Specific examples of the unsaturated fatty acid amides include oleic acid amide, erucic acid amide, and the like. Specific examples of the substituted amides include N-oleyl palmitic acid amide, N-stearyl stearic acid amide, N-stearyl oleic acid amide, N-oleyl stearic acid amide, N-stearyl erucic acid amide, and the like. Further, specific examples of the methylol amides include methylol stearic acid amide, and the like. Specific examples of the saturated fatty acid bisamides include methylene bisstearic acid amide, ethylene biscapric acid amide, ethylene bislauric acid amide, ethylene bisstearic acid amide, ethylene bishydroxystearic acid amide, ethylene bisbehenic acid amide, hexamethylene bisstearic acid amide, hexamethylene bisbehenic acid amide, hexamethylene hydroxystearic acid amide, N,N'-distearyl adipic acid amide, N,N'-distearyl sebacic acid amide, and the like. Specific examples of the unsaturated fatty acid bisamides include ethylene bisoleic acid amide, ethylene biserucic acid amide, hexamethylene bisoleic acid amide, N,N'-dioleyl adipic acid amide, N,N'-dioleyl sebacic acid amide, and the like. Specific examples of the fatty acid ester amides include stearamide ethyl stearate, and the like. Further, specific examples of the aromatic bisamides include m-xylylene bisstearic acid amide, m-xylylene bishydroxystearic acid amide, N,N'-distearyl isophthalic acid amide, and the like.The lubricant may be used alone or in combination of two or more kinds, and it is preferable to use two or more kinds in combination.

[0074] When the lubricant is present on the surface of the polyolefin layer 2, its amount of presence is not particularly limited, but from the viewpoint of enhancing the moldability of the laminated film, it is preferably about 1 mg / m 2 or more, more preferably about 3 mg / m 2 or more, still more preferably about 5 mg / m 2 or more, still more preferably about 10 mg / m 2 or more, still more preferably about 15 mg / m 2 or more, and preferably about 50 mg / m 2 or less, more preferably about 40 mg / m 2 or less. The preferable range is about 1 to 50 mg / m 2 level, about 1 to 40 mg / m 2 level, about 3 to 50 mg / m 2 level, about 3 to 40 mg / m 2 level, about 5 to 50 mg / m 2 level, about 5 to 40 mg / m 2 level, about 10 to 50 mg / m 2 level, about 10 to 40 mg / m 2 level, about 15 to 50 mg / m 2 level, about 15 to 40 mg / m 2 level can be mentioned.

[0075] When a lubricant is present inside the polyolefin layer 2, its amount of presence is not particularly limited. However, from the perspective of enhancing the moldability of the laminated film, it is preferably about 100 ppm or more, more preferably about 300 ppm or more, still more preferably about 500 ppm or more, and is preferably about 3000 ppm or less, more preferably about 2000 ppm or less. Preferred ranges include about 100 to 3000 ppm, about 100 to 2000 ppm, about 300 to 3000 ppm, about 300 to 2000 ppm, about 500 to 3000 ppm, and about 500 to 2000 ppm. When two or more types of lubricants are present inside the polyolefin layer 2, the above-mentioned amount of lubricant is the total amount of lubricants. Also, when two or more types of lubricants are present inside the polyolefin layer 2, the amount of presence of the first type of lubricant is not particularly limited. However, from the perspective of enhancing the moldability of the laminated film, it is preferably about 100 ppm or more, more preferably about 300 ppm or more, still more preferably about 500 ppm or more, and is preferably about 3000 ppm or less, more preferably about 2000 ppm or less. Preferred ranges include about 100 to 3000 ppm, about 100 to 2000 ppm, about 300 to 3000 ppm, about 300 to 2000 ppm, about 500 to 3000 ppm, and about 500 to 2000 ppm. The amount of presence of the second type of lubricant is not particularly limited. However, from the perspective of enhancing the moldability of the laminated film, it is preferably about 50 ppm or more, more preferably about 100 ppm or more, still more preferably about 200 ppm or more, and is preferably about 1500 ppm or less, more preferably about 1000 ppm or less. Preferred ranges include about 50 to 1500 ppm, about 50 to 1000 ppm, about 100 to 1500 ppm, about 100 to 1000 ppm, about 200 to 1500 ppm, and about 200 to 1000 ppm.

[0076] The lubricant present on the surface of the polyolefin layer 2 may be one obtained by exuding the lubricant contained in the resin constituting the polyolefin layer 2, or may be one with a lubricant applied to the surface of the polyolefin layer 2.

[0077] Also, the thickness of the polyolefin layer 2 is preferably about 15 μm or more, more preferably 30 μm or more, still more preferably 50 μm or more, and even more preferably 60 μm or more. Also, it is preferably about 150 μm or less, more preferably 120 μm or less, still more preferably 100 μm or less. A preferable range is about 60 to 100 μm.

[0078] [Resin layer 3] In the laminated film 10 of the present disclosure, the resin layer 3 is a layer provided as necessary on the side opposite to the polyolefin layer 2 side of the barrier layer 1. As described above, the laminated film 10 of the present disclosure can be used, for example, such that the resin layer 3 is on the outer surface side of the bipolar lithium ion battery 20. When the resin layer 3 has heat-sealability, the resin layer 3 of the laminated film 10 of the present disclosure can be fixed to the outer surface of the bipolar lithium ion battery 20 by heat-sealing.

[0079] There are no particular restrictions on the material for forming the resin layer 3. The resin layer 3 can be formed using a resin, and the resin may contain additives described later.

[0080] The resin layer 3 can be formed, for example, by a resin film. When the resin layer 3 is formed by a resin film, when manufacturing the laminated film 10 of the present disclosure by laminating the resin layer 3 with the barrier layer 1 or the like, a pre-formed resin film may be used as the resin layer 3. Also, the resin for forming the resin layer 3 may be formed into a film on the surface of the barrier layer 1 or the like by extrusion molding, coating, or the like to form the resin layer 3 formed by a resin film. The resin film may be an unstretched film or a stretched film. Examples of the stretched film include a uniaxially stretched film and a biaxially stretched film, and a biaxially stretched film is preferable. Examples of the stretching method for forming the biaxially stretched film include a sequential biaxial stretching method, an inflation method, and a simultaneous biaxial stretching method. Examples of the method for applying the resin include a roll coating method, a gravure coating method, and an extrusion coating method.

[0081] Examples of the resin for forming the resin layer 3 include resins such as polyester, polyamide, polyolefin resin, epoxy resin, acrylic resin, fluororesin, polyurethane, silicone resin, and phenol resin, and modified products of these resins. Further, the resin for forming the resin layer 3 may be a copolymer of these resins, a modified product of the copolymer, or a mixture of these resins.

[0082] The resin layer 3 preferably contains these resins as a main component, and more preferably contains a polyolefin resin, polyester, or polyamide as a main component. Here, the main component means a resin component having a content of, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more, still more preferably 90% by mass or more, still more preferably 95% by mass or more, still more preferably 98% by mass or more, and still more preferably 99% by mass or more among the resin components contained in the resin layer 3. For example, when the resin layer 3 contains a polyolefin resin, polyester, or polyamide as a main component, it means that the content of the polyolefin resin, polyester, or polyamide among the resin components contained in the resin layer 3 is, respectively, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more, still more preferably 90% by mass or more, still more preferably 95% by mass or more, still more preferably 98% by mass or more, and still more preferably 99% by mass or more.

[0083] Examples of the resin for forming the resin layer 3 preferably include polyolefin resin, polyester, and polyamide.

[0084] When the resin layer 3 contains a polyolefin resin, the resin layer 3 can be the same layer as the polyolefin layer 2 described above. That is, there is no particular limitation as long as the resin layer 3 is a layer containing a polyolefin resin. The polyolefin resin is a resin containing a polyolefin skeleton such as polyolefin and acid-modified polyolefin described above.

[0085] Examples of the polyester include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolyester. Examples of the copolyester include copolyesters having ethylene terephthalate as the main repeating unit. Specifically, examples include copolyester polyethylenes (hereinafter abbreviated following polyethylene(terephthalate / isophthalate)) obtained by polymerizing ethylene isophthalate with ethylene terephthalate as the main repeating unit, polyethylene(terephthalate / adipate), polyethylene(terephthalate / sodium sulfoisophthalate), polyethylene(terephthalate / sodium isophthalate), polyethylene(terephthalate / phenyl-dicarboxylate), polyethylene(terephthalate / decanedicarboxylate), and the like. These polyesters may be used alone or in combination of two or more.

[0086] Examples of the polyamide include aliphatic polyamides such as nylon 6, nylon 66, nylon 610, nylon 12, nylon 46, and copolymers of nylon 6 and nylon 66; hexamethylenediamine-isophthalic acid-terephthalic acid copolyamides such as nylon 6I, nylon 6T, nylon 6IT, and nylon 6I6T (where I represents isophthalic acid and T represents terephthalic acid) containing structural units derived from terephthalic acid and / or isophthalic acid, and polyamides containing aromatic groups such as polyamide MXD6 (polymetaxylylene adipamide); alicyclic polyamides such as polyamide PACM6 (poly-bis(4-aminocyclohexyl)methane adipamide); furthermore, polyamides copolymerized with lactam components or isocyanate components such as 4,4'-diphenylmethane-diisocyanate, polyesteramide copolymers and polyetheresteramide copolymers which are copolymers of copolyamides with polyesters or polyalkylene ether glycols; and polyamides such as these copolymers. These polyamides may be used alone or in combination of two or more.

[0087] The resin layer 3 preferably contains at least one of a polyolefin film, a polyester film, a polyamide film, and a polyolefin film, preferably contains at least one of an unstretched polyolefin film, a stretched polyester film, a stretched polyamide film, and a stretched polyolefin film, and more preferably contains at least one of an unstretched polyolefin film, a stretched polyethylene terephthalate film, a stretched polybutylene terephthalate film, a stretched nylon film, and a stretched polypropylene film. Even more preferably, it contains at least one of an unstretched polyolefin film, a biaxially stretched polyethylene terephthalate film, a biaxially stretched polybutylene terephthalate film, a biaxially stretched nylon film, and a biaxially stretched polypropylene film.

[0088] The resin layer 3 may be a single layer or may be composed of two or more layers. When the resin layer 3 is composed of two or more layers, the resin layer 3 may be a laminate in which resin films are laminated with an adhesive or the like, or may be a laminate of resin films obtained by coextruding resins to form two or more layers. Further, the laminate of resin films obtained by coextruding resins to form two or more layers may be used as the resin layer 3 without stretching, or may be uniaxially or biaxially stretched to form the resin layer 3.

[0089] In the resin layer 3, specific examples of the laminate of two or more resin films include a laminate of a polyester film and a nylon film, a laminate of two or more nylon films, a laminate of two or more polyester films, etc. Preferably, a laminate of a stretched nylon film and a stretched polyester film, a laminate of two or more stretched nylon films, and a laminate of two or more stretched polyester films are preferred. For example, when the resin layer 3 is a laminate of two resin films, a laminate of a polyester resin film and a polyester resin film, a laminate of a polyamide resin film and a polyamide resin film, or a laminate of a polyester resin film and a polyamide resin film is preferred, and a laminate of a polyethylene terephthalate film and a polyethylene terephthalate film, a laminate of a nylon film and a nylon film, or a laminate of a polyethylene terephthalate film and a nylon film is more preferred. Further, since the polyester resin is less likely to change color when, for example, an electrolytic solution adheres to the surface, when the resin layer 3 is a laminate of two or more resin films, it is preferable that the polyester resin film is located on the outermost layer of the resin layer 3.

[0090] When the resin layer 3 is a laminate of two or more resin films, the two or more resin films may be laminated via an adhesive. Preferred adhesives include the same ones as the adhesives exemplified in the adhesive layers 4 and 5 described later. The method of laminating two or more resin films is not particularly limited, and known methods can be adopted. For example, dry lamination method, sandwich lamination method, extrusion lamination method, thermal lamination method, etc. can be mentioned, and preferably the dry lamination method can be mentioned. When laminating by the dry lamination method, it is preferable to use a polyurethane adhesive as the adhesive. At this time, the thickness of the adhesive is, for example, about 2 to 5 μm. Also, an anchor coat layer may be formed on the resin film and laminated. The anchor coat layer includes the same ones as the adhesives exemplified in the adhesive layers 4 and 5 described later. At this time, the thickness of the anchor coat layer is, for example, about 0.01 to 1.0 μm.

[0091] Further, additives such as lubricants, flame retardants, antiblocking agents, antioxidants, light stabilizers, tackifiers, antistatic agents, etc. may be present on at least one of the surface and inside of the resin layer 3. Only one type of additive may be used, or two or more types may be mixed and used.

[0092] In the present disclosure, from the viewpoint of enhancing the moldability of the laminated film, it is preferable that a lubricant is present on at least one of the surface and the inside of the resin layer 3. The lubricant is not particularly limited, but preferably an amide-based lubricant. Specific examples of the amide-based lubricant include, for example, saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylol amides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid ester amides, aromatic bisamides, and the like. Specific examples of the saturated fatty acid amides include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, hydroxystearic acid amide, and the like. Specific examples of the unsaturated fatty acid amides include oleic acid amide, erucic acid amide, and the like. Specific examples of the substituted amides include N-oleyl palmitic acid amide, N-stearyl stearic acid amide, N-stearyl oleic acid amide, N-oleyl stearic acid amide, N-stearyl erucic acid amide, and the like. Specific examples of the methylol amides include methylol stearic acid amide, and the like. Specific examples of the saturated fatty acid bisamides include methylene bisstearic acid amide, ethylene biscapric acid amide, ethylene bislauric acid amide, ethylene bisstearic acid amide, ethylene bishydroxystearic acid amide, ethylene bisbehenic acid amide, hexamethylene bisstearic acid amide, hexamethylene bisbehenic acid amide, hexamethylene hydroxystearic acid amide, N,N'-distearyl adipic acid amide, N,N'-distearyl sebacic acid amide, and the like. Specific examples of the unsaturated fatty acid bisamides include ethylene bisoleic acid amide, ethylene biserucic acid amide, hexamethylene bisoleic acid amide, N,N'-dioleyl adipic acid amide, N,N'-dioleyl sebacic acid amide, and the like. Specific examples of the fatty acid ester amides include stearamide ethyl stearate, and the like. Specific examples of the aromatic bisamides include m-xylylene bisstearic acid amide, m-xylylene bishydroxystearic acid amide, N,N'-distearyl isophthalic acid amide, and the like. The lubricant may be used alone or in combination of two or more, and it is preferable to use a combination of two or more.

[0093] When a lubricant is present on the surface of the resin layer 3, the amount thereof is not particularly limited. For example, it is about 3 mg / m 2 or more, preferably about 4 mg / m 2 or more, about 5 mg / m 2 or more. Further, as the amount of the lubricant present on the surface of the resin layer 3, for example, it is about 15 mg / m 2 or less, preferably about 14 mg / m 2 or less, about 10 mg / m 2 or less. Further, the preferable range of the amount of the lubricant present on the surface of the resin layer 3 is about 3 to 15 mg / m 2 level, about 3 to 14 mg / m 2 level, about 3 to 10 mg / m 2 level, about 4 to 15 mg / m 2 level, about 4 to 14 mg / m 2 level, about 4 to 10 mg / m 2 level, about 5 to 15 mg / m 2 level, about 5 to 14 mg / m 2 level, about 5 to 10 mg / m 2 level.

[0094] The lubricant present on the surface of the resin layer 3 may be one obtained by exuding the lubricant contained in the resin constituting the resin layer 3, or may be one obtained by applying a lubricant to the surface of the resin layer 3.

[0095] Regarding the thickness of the resin layer 3, it is preferably about 15 μm or more, more preferably 30 μm or more, still more preferably 50 μm or more, still more preferably 60 μm or more. Also, it is preferably about 150 μm or less, more preferably 120 μm or less, still more preferably 100 μm or less. The preferable range includes about 15 to 150 μm, about 15 to 120 μm, about 15 to 100 μm, about 30 to 150 μm, about 30 to 120 μm, about 30 to 100 μm, about 50 to 150 μm, about 50 to 120 μm, about 50 to 100 μm, about 60 to 150 μm, about 60 to 120 μm, about 60 to 100 μm.

[0096] [Adhesive layers 4, 5] In the laminated film 10 of the present disclosure, the adhesive layer 4 is a layer provided between the barrier layer 1 and the polyolefin layer 2 as needed for the purpose of enhancing the adhesiveness therebetween. Further, the adhesive layer 4 is a layer provided between the barrier layer 1 and the resin layer 3 as needed for the purpose of enhancing the adhesiveness therebetween.

[0097] The adhesive layers 4 and 5 are each formed of an adhesive capable of bonding the barrier layer 1 and the polyolefin layer 2, or the barrier layer 1 and the resin layer 3. The adhesive used for forming the adhesive layers 4 and 5 is not limited, and may be any of a chemical reaction type, a solvent volatile type, a hot melt type, a hot press type, etc. Further, it may be a two-component curable adhesive (two-component adhesive), a one-component curable adhesive (one-component adhesive), or a resin without a curing reaction. Also, the adhesive layers 4 and 5 may be single-layer or multi-layer.

[0098] Specific examples of the adhesive component contained in the adhesive include polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolymerized polyester; polyethers; polyurethanes; epoxy resins; phenolic resins; polyamides such as nylon 6, nylon 66, nylon 12, and copolymerized polyamide; polyolefin-based resins such as polyolefin, cyclic polyolefin, acid-modified polyolefin, and acid-modified cyclic polyolefin; polyvinyl acetate; cellulose; (meth)acrylic resins; polyimides; polycarbonates; amino resins such as urea resin and melamine resin; rubbers such as chloroprene rubber, nitrile rubber, and styrene-butadiene rubber; and silicone resins. These adhesive components may be used alone or in combination of two or more. Among these adhesive components, a polyurethane adhesive is preferably mentioned. Further, the resin serving as these adhesive components can enhance the adhesive strength by using an appropriate curing agent in combination. The curing agent is appropriately selected from polyisocyanates, polyfunctional epoxy resins, oxazoline group-containing polymers, polyamine resins, acid anhydrides, etc., according to the functional groups of the adhesive components.

[0099] Examples of the polyurethane adhesive include a polyurethane adhesive comprising a first agent containing a polyol compound and a second agent containing an isocyanate compound. Preferably, examples thereof include a two-component curable polyurethane adhesive in which a polyol such as a polyester polyol, a polyether polyol, or an acrylic polyol is used as the first agent and an aromatic or aliphatic polyisocyanate is used as the second agent. Further, examples of the polyurethane adhesive include a polyurethane adhesive comprising a polyurethane compound obtained by previously reacting a polyol compound and an isocyanate compound and an isocyanate compound. Further, examples of the polyurethane adhesive include a polyurethane adhesive comprising a polyurethane compound obtained by previously reacting a polyol compound and an isocyanate compound and a polyol compound. Further, examples of the polyurethane adhesive include a polyurethane adhesive cured by reacting a polyurethane compound obtained by previously reacting a polyol compound and an isocyanate compound with moisture in the air or the like. As the polyol compound, it is preferable to use a polyester polyol having a hydroxyl group not only at the terminal of the repeating unit but also in the side chain. Examples of the second agent include aliphatic, alicyclic, aromatic, and araliphatic isocyanate compounds. Examples of the isocyanate compound include hexamethylene diisocyanate (HDI), xylylene diisocyanate (XDI), isophorone diisocyanate (IPDI), hydrogenated XDI (H6XDI), hydrogenated MDI (H12MDI), tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), naphthalene diisocyanate (NDI), and the like. Further, examples thereof include polyfunctional isocyanate modified products derived from one or more of these diisocyanates. Further, a multimer (for example, a trimer) can also be used as the polyisocyanate compound. Examples of such multimers include adducts, biurets, and nurates. Since the adhesive layers 4 and 5 are formed of a polyurethane adhesive, the laminated film is imparted with excellent electrolyte resistance, and even when an electrolyte adheres to the side surface, peeling of the polyolefin layer 2 or the resin layer 3 from the barrier layer 1 is suppressed.

[0100] Further, as long as the adhesives layers 4 and 5 do not inhibit adhesiveness, addition of other components is allowed, and they may contain a colorant, a thermoplastic elastomer, a tackifier, a filler, etc. Since the adhesives layers 4 and 5 contain a colorant, the laminated film can be colored. As the colorant, known ones such as pigments and dyes can be used. Also, only one type of colorant may be used, or two or more types may be mixed and used.

[0101] The type of the pigment is not particularly limited as long as it does not impair the adhesiveness of the adhesives layers 4 and 5. Examples of the organic pigment include pigments such as azo-based, phthalocyanine-based, quinacridone-based, anthraquinone-based, dioxazine-based, indigothioindigo-based, perinone-perylene-based, isoindolinine-based, and benzimidazolone-based pigments. Examples of the inorganic pigment include pigments such as carbon black-based, titanium oxide-based, cadmium-based, lead-based, chromium oxide-based, and iron-based pigments. In addition, fine powders of mica and fish scale foil are also included.

[0102] Among the colorants, for example, in order to make the appearance of the laminated film black, carbon black is preferable.

[0103] The average particle diameter of the pigment is not particularly limited. For example, it is about 0.05 to 5 μm, preferably about 0.08 to 2 μm. The average particle diameter of the pigment is the median diameter measured by a laser diffraction / scattering particle size distribution measuring device.

[0104] The content of the pigment in the adhesives layers 4 and 5 is not particularly limited as long as the laminated film is colored. For example, it is about 5 to 60% by mass, preferably 10 to 40% by mass.

[0105] The thicknesses of the adhesive layers 4 and 5 are not particularly limited as long as the barrier layer 1 can be adhered to the polyolefin layer 2 or the resin layer 3. For example, the thickness is about 1 μm or more, about 2 μm or more. Also, the thicknesses of the adhesive layers 4 and 5 are, for example, about 10 μm or less, about 5 μm or less. Moreover, as for the preferable range of the thicknesses of the adhesive layers 4 and 5, examples include about 1 to 10 μm, about 1 to 5 μm, about 2 to 10 μm, and about 2 to 5 μm.

[0106] [Coloring layer] The coloring layer is a layer provided between the barrier layer 1 and the adhesive layers 4 and 5 as needed (illustration is omitted). When the laminated film 10 of the present disclosure has the adhesive layers 4 and 5, a coloring layer may be provided between the polyolefin layer 2 and the adhesive layer 4, between the adhesive layer 4 and the barrier layer 1, between the barrier layer 1 and the adhesive layer 5, and between the adhesive layer 5 and the resin layer 3, respectively. Also, a coloring layer may be provided outside the resin layer 3. By providing the coloring layer, the laminated film can be colored.

[0107] The coloring layer can be formed, for example, by applying an ink containing a colorant to the surface of the polyolefin layer 2, the surface of the barrier layer 1, the surface of the resin layer 3, etc. As the colorant, known ones such as pigments and dyes can be used. Also, only one type of colorant may be used, or two or more types may be mixed and used.

[0108] Specific examples of the colorant contained in the coloring layer are the same as those exemplified in the column of [adhesive layers 4 and 5].

[0109] [Bipolar lithium-ion battery] The laminated film of the present disclosure can be suitably used for the application of being disposed on the outer surface of a bipolar lithium-ion battery. The lithium-ion battery may be an all-solid battery, a semi-solid battery, or a clay battery.

[0110] The bipolar lithium-ion battery 20 of the present disclosure is a bipolar lithium-ion battery 20 that utilizes the laminated film 10 of the present disclosure. That is, in the bipolar lithium-ion battery 20 of the present disclosure, a part of the outer surface of the bipolar lithium-ion battery 20 is provided with the laminated film 10 of the present disclosure described above. The laminated film 10 of the present disclosure is arranged so as to straddle the ridge line portion 20c from the main surface 20a to the side surface 20b of the outer surface of the bipolar lithium-ion battery 20.

[0111] As described above, for example, FIGS. 5 to 9 show how the laminated film 10 of the present disclosure is arranged on the bipolar lithium-ion battery 20. The bipolar lithium-ion battery 20 shown in FIGS. 5 to 9 has a rectangular parallelepiped outer shape and includes two main surfaces 20a facing each other, four side surfaces 20b, and a ridge line portion 20c located at the boundary between the main surface 20a and the side surface 20b. End collectors 21 (i.e., electrodes) are exposed on the two main surfaces 20a, respectively. Between the end collectors 21, members provided in the bipolar lithium-ion battery, such as a current collector 22, a positive electrode layer 23, a negative electrode layer 24, and an electrolyte 25, are arranged and function as a bipolar lithium-ion battery.

[0112] As described above, the outer shape of the bipolar lithium-ion battery 20 is not particularly limited, and examples include a rectangular parallelepiped shape (i.e., the main surface is rectangular in plan view) and a cylindrical shape (i.e., the main surface is circular in plan view).

[0113] In the bipolar lithium-ion battery 20 of the present disclosure, it is preferable that the laminated film 10 is heat-sealed to the outer surface of the bipolar lithium-ion battery 20. An adhesive film may be interposed between the laminated film 10 and the outer surface of the bipolar lithium-ion battery 20 and heat-sealed. Examples of the adhesive film used in that case include a single-layer film of an acid-modified polyolefin and a laminate of an acid-modified polyolefin and a polyolefin.

[0114] FIG. 10 is a schematic cross-sectional view showing an example of a mode in which the laminated film 10 of the present disclosure is applied to the outer surface of the bipolar lithium ion battery 20. FIG. 10 corresponds to the cross-sectional view of FIG. 7. In FIG. 10, between the end current collectors 21 and the current collector 22, and further between the current collectors 22, are filled with a sealing member 26 to constitute the side surface 20b, and the entire surface of the side surface 20b is covered with the laminated film 10. In FIG. 7, since it is a perspective view seen from above the bipolar lithium ion battery 20, the bottom surface side is not shown, but on the bottom surface side as well, the outer peripheral edge of the end current collector 21 is covered with the laminated film 10.

Example

[0115] The present disclosure will be described in detail below with reference to examples and comparative examples. However, the present disclosure is not limited to the examples.

[0116] <Manufacture of Laminated Film for Bipolar Lithium Ion Battery> (Example 1) An aluminum alloy foil (JIS H4160: 1994 A8021H-O (thickness 40 μm)) was prepared as the barrier layer. Also, two un-stretched polypropylene films (CPP thickness 70 μm, melting point 163 ° C) were prepared as the polyolefin layer and the resin layer. Using a two-component urethane adhesive (polyol compound and aromatic isocyanate compound), the polyolefin layer was laminated on both sides of the barrier layer, and by performing an aging treatment, a laminated film for a bipolar lithium ion battery in which a polyolefin layer (CPP 70 μm) / adhesive layer (1.5 μm) / barrier layer (aluminum alloy foil 40 μm) / adhesive layer (1.5 μm) / resin layer (polyolefin layer CPP 70 μm) were laminated in order was manufactured.

[0117] (Example 2) A bipolar lithium-ion battery laminated film in which a polyolefin layer (CPP 80 μm) / adhesive layer (1.5 μm) / barrier layer (aluminum alloy foil 40 μm) / adhesive layer (1.5 μm) / resin layer (polyolefin layer CPP 80 μm) are laminated in order was produced in the same manner as in Example 1, except that two un-stretched polypropylene films (CPP thickness 80 μm, melting point 163 °C) were used as the polyolefin layer and the resin layer.

[0118] (Example 3) A bipolar lithium-ion battery laminated film in which a polyolefin layer (CPP 100 μm) / adhesive layer (1.5 μm) / barrier layer (aluminum alloy foil 40 μm) / adhesive layer (1.5 μm) / resin layer (polyolefin layer CPP 100 μm) are laminated in order was produced in the same manner as in Example 1, except that two un-stretched polypropylene films (CPP thickness 100 μm, melting point 163 °C) were used as the polyolefin layer and the resin layer.

[0119] (Example 4) An aluminum alloy foil (JIS H4160:1994 A8021H-O (thickness 40 μm)) was prepared as the barrier layer. By melt-extruding maleic anhydride-modified polypropylene (melting point 160 °C) on both sides of the barrier layer to laminate the polyolefin layer and the resin layer, a bipolar lithium-ion battery laminated film in which a polyolefin layer (PPa 70 μm) / barrier layer (aluminum alloy foil 40 μm) / resin layer (polyolefin layer PPa 70 μm) are laminated in order was produced.

[0120] (Example 5) A bipolar lithium-ion battery laminated film in which a polyolefin layer (LDPE thickness 70 μm, melting point 130 °C) / adhesive layer (1.5 μm) / barrier layer (aluminum alloy foil 40 μm) / adhesive layer (1.5 μm) / resin layer (polyolefin layer LDPE thickness 70 μm) are laminated in order was produced in the same manner as in Example 1, except that two low-density polyethylene films (LDPE thickness 70 μm) were used as the polyolefin layer and the resin layer.

[0121] (Example 6) A laminated film for a bipolar lithium-ion battery in which a polyolefin layer (HDPE with a thickness of 70 μm and a melting point of 130°C) / adhesive layer (1.5 μm) / barrier layer (aluminum alloy foil 40 μm) / adhesive layer (1.5 μm) / resin layer (polyolefin layer HDPE with a thickness of 70 μm) were laminated in this order was produced in the same manner as in Example 1, except that two high-density polyethylene films (HDPE with a thickness of 70 μm) were used as the polyolefin layer and the resin layer.

[0122] (Example 7) An aluminum alloy foil (JIS H4160:1994 A8021H-O (thickness 60 μm)) was prepared as the barrier layer. As the resin for forming the polyolefin layer, maleic anhydride-modified polypropylene (melting point 160°C) and polypropylene (melting point 140°C) were prepared. As the resin layer, a polyethylene terephthalate (PET) film (thickness 12 μm) and a stretched nylon (ONy) film (thickness 25 μm) were prepared as a film adhered with an adhesive (two-component urethane adhesive (the thickness after curing of the polyol compound and the aromatic isocyanate compound is 3 μm)). On one side of the barrier layer, maleic anhydride-modified polypropylene and polypropylene were melt-extruded to form a maleic anhydride-modified polypropylene layer (thickness 40 μm) and a polypropylene layer (thickness 40 μm) as the polyolefin layer. Next, on one side of the barrier layer, the stretched nylon film side of the resin layer was adhered with an adhesive (two-component urethane adhesive (the thickness after curing of the polyol compound and the aromatic isocyanate compound is 3 μm)), and an aging treatment was carried out to produce a laminated film for a bipolar lithium-ion battery in which a polyolefin layer (PP40 μm / PPa40 μm) / barrier layer (aluminum alloy foil 60 μm) / adhesive layer (3 μm) / resin layer (stretched nylon (ONy) film (thickness 25 μm) / adhesive (3 μm) / polyethylene terephthalate (PET) film (thickness 12 μm)) were laminated in this order.

[0123] (Example 8) As the resin layer, a polyethylene terephthalate (PET) film (thickness 25 μm) and a stretched nylon (ONy) film (thickness 25 μm) were used, except that the film was adhered with an adhesive (two-component urethane adhesive (polyol compound and aromatic isocyanate compound, thickness after curing 3 μm)). In the same manner as in Example 7, a laminated film for a bipolar lithium-ion battery in which a polyolefin layer (PP 40 μm / PPa 40 μm) / barrier layer (aluminum alloy foil 60 μm) / adhesive layer (3 μm) / resin layer (stretched nylon (ONy) film (thickness 25 μm) / adhesive (3 μm) / polyethylene terephthalate (PET) film (thickness 25 μm)) were laminated in order was manufactured.

[0124] (Example 9) As the barrier layer, an aluminum alloy foil (JIS H4160:1994 A8021H-O (thickness 80 μm)) was used. In the same manner as in Example 8, a laminated film for a bipolar lithium-ion battery in which a polyolefin layer (PP 40 μm / PPa 40 μm) / barrier layer (aluminum alloy foil 80 μm) / adhesive layer (3 μm) / resin layer (stretched nylon (ONy) film (thickness 25 μm) / adhesive (3 μm) / polyethylene terephthalate (PET) film (thickness 25 μm)) were laminated in order was manufactured.

[0125] (Example 10) As the barrier layer, an aluminum alloy foil (JIS H4160:1994 A8021H-O (thickness 60 μm)) with a Si content of 0.8 mass% or less was used. In the same manner as in Example 8, a laminated film for a bipolar lithium-ion battery in which a polyolefin layer (PP 40 μm / PPa 40 μm) / barrier layer (aluminum alloy foil 60 μm) / adhesive layer (3 μm) / resin layer (stretched nylon (ONy) film (thickness 25 μm) / adhesive (3 μm) / polyethylene terephthalate (PET) film (thickness 25 μm)) were laminated in order was manufactured.

[0126] (Example 11) An unstretched polypropylene film (CPP thickness 80 μm, melting point 163°C) was used as the polyolefin layer, and an olefin-based adhesive (acid-modified polypropylene and epoxy compound, thickness after curing 3 μm) was used as the adhesive layer. Otherwise, in the same manner as in Example 10, a laminated film for a bipolar lithium-ion battery in which a polyolefin layer (CPP 80 μm) / adhesive layer (3 μm) / barrier layer (aluminum alloy foil 60 μm) / adhesive layer (3 μm) / resin layer (stretched nylon (ONy) film (thickness 25 μm) / adhesive (3 μm) / polyethylene terephthalate (PET) film (thickness 25 μm)) were laminated in sequence was produced.

[0127] (Example 12) A laminated film for a bipolar lithium-ion battery in which a polyolefin layer (PP40 μm / PPa40 μm) / barrier layer (aluminum alloy foil 60 μm) / adhesive layer (3 μm) / resin layer (stretched nylon (ONy) film (thickness 25 μm) / adhesive (3 μm) / polyethylene terephthalate (PET) film (thickness 12 μm)) were laminated in sequence was produced in the same manner as in Example 1, except that an aluminum alloy foil (JIS H4160:1994 A8021H-O (thickness 60 μm)) with an Si content of 0.8 mass% or less was used as the barrier layer.

[0128] (Example 13) As the resin layer, a polyethylene terephthalate (PET) film (thickness 12 μm) and a stretched nylon (ONy) film (thickness 25 μm) were adhered with an adhesive (two-component urethane adhesive (the thickness after curing of the polyol compound and the aromatic isocyanate compound is 3 μm)). Except for using an aluminum alloy foil (JIS H4160:1994 A8021H-O (thickness 60 μm)) with a Si content of 0.8 mass% or less as the barrier layer, in the same manner as in Example 11, a laminated film for a bipolar lithium-ion battery in which a polyolefin layer (CPP 80 μm) / adhesive layer (3 μm) / barrier layer (aluminum alloy foil 60 μm) / adhesive layer (3 μm) / resin layer (stretched nylon (ONy) film (thickness 25 μm) / adhesive (3 μm) / polyethylene terephthalate (PET) film (thickness 12 μm)) were laminated in order was manufactured.

[0129] <Electrolyte resistance test> The laminated film for each bipolar lithium-ion battery was cut into a rectangular shape of 15 mm in the (TD direction) × 70 mm in the (MD direction), and this was put into a glass bottle and completely immersed in an electrolytic solution (1 mol / liter lithium hexafluorophosphate solution, and the solvent was ethylene carbonate:diethyl carbonate:dimethyl carbonate = 1:1:1 (volume ratio)). The glass bottle was sealed and stored in an oven at 85°C for 24 hours. The laminated film for the bipolar lithium-ion battery was taken out from the glass bottle, washed with water, the moisture was wiped off, and for the ends of each laminated film for the bipolar lithium-ion battery, a measurement sample was prepared by peeling between the aluminum alloy foil and the polyolefin layer. Using the obtained measurement sample, in an atmosphere of 25°C and 50% RH, with a tensile tester (manufactured by Shimadzu Corporation, AG-Xplus (product name)), under the conditions of 180-degree peeling, a tensile speed of 50 mm / min, and a gauge length of 50 mm, the peeling between the aluminum alloy foil and the polyolefin layer was carried out, and the laminate strength (peeling strength (N / 15 mm)) was measured. The measurement conditions were 180-degree peeling and a tensile speed of 50 mm / min in an atmosphere of 25°C and 50% RH. Under the condition of a gauge length of 50 mm, when the gauge length became 57 mm, the strength was taken as the laminate strength (N / 15 mm), and the average value of three measurements was taken. The evaluation criteria for the electrolyte resistance are as follows. The results are shown in Table 1. (Evaluation Criteria for Electrolyte Resistance) A+: The laminate strength is 3 N / 15 mm or more. A: The laminate strength is 2 N / 15 mm or more and less than 3 N / 15 mm. B: The laminate strength is less than 2 N / 15 mm.

[0130] <Limit Formability> The laminated film for bipolar lithium-ion batteries was cut into rectangles with a length (MD direction) of 90 mm × width (TD direction) of 150 mm to obtain test samples. The MD of the laminated film for bipolar lithium-ion batteries corresponds to the rolling direction (RD) of the aluminum alloy foil, and the TD of the laminated film for bipolar lithium-ion batteries corresponds to the TD of the aluminum alloy foil. In an environment of 25°C, this sample was formed using a rectangular molding die (female die) with a diameter of 31.6 mm (MD direction) × 54.5 mm (TD direction) (the surface has a maximum height roughness (the nominal value of Rz) of 3.2 μm as specified in Table 2 of the reference surface roughness standard piece attached to JIS B 0659-1:2002. Corner R 2.0 mm, edge line R 1.0 mm) and a corresponding molding die (male die) (the surface of the edge line part has a maximum height roughness (the nominal value of Rz) of 1.6 μm as specified in Table 2 of the reference surface roughness standard piece attached to JIS B 0659-1:2002, and the surface other than the edge line part has a maximum height roughness (the nominal value of Rz) of 3.2 μm as specified in Table 2 of the reference surface roughness standard piece attached to JIS B 0659-1:2002. Corner R 2.0 mm, edge line R 1.0 mm). Cold forming (drawing one-step forming) was performed on 10 samples each by changing the forming depth in 0.5 mm units from a forming depth of 0.5 mm at a holding pressure (surface pressure) of 0.25 MPa. At this time, the above test sample was placed on the female die so that the polyolefin layer side was located on the male die side for forming. Also, the clearance between the male die and the female die was set to 0.3 mm. For the samples after cold forming, a penlight was used to shine light in a dark room, and it was confirmed whether pinholes or cracks occurred in the aluminum alloy foil by the transmission of light. The deepest forming depth at which no pinholes or cracks occurred in all 10 samples of the aluminum alloy foil was defined as Amm, and the number of samples in which pinholes or the like occurred at the shallowest forming depth at which pinholes or the like occurred in the aluminum alloy foil was defined as B. The value calculated by the following formula was rounded to the second decimal place, and this was taken as the limit forming depth of the laminated film. The evaluation criteria for the limit formability are as follows. The results are shown in Table 1. Limit forming depth = Amm + (0.5 mm / 10 pieces) × (10 pieces - B pieces) (Evaluation Criteria for the Limiting Forming Depth) A+: The limiting forming depth is 8.0 mm or more A: The limiting forming depth is 4.0 mm or more and less than 8.0 mm. B: The limiting forming depth is 3.0 mm or more and less than 4.0 mm. C: The limiting forming depth is less than 3.0 mm.

[0131]

Table 1

[0132]

Table 2

[0133] As is clear from the results shown in Table 1 and Table 2, the laminated films for bipolar lithium ion batteries manufactured in Examples 1 to 13 are excellent in electrolyte resistance and formability, and are suitable as laminated films disposed on a part of the outer surface of bipolar lithium ion batteries.

[0134] As described above, the present disclosure provides an invention in the following aspects. Item 1. A laminated film disposed on a part of the outer surface of a bipolar lithium ion battery, The laminated film includes at least a barrier layer and a polyolefin layer provided on one side of the barrier layer, and comprises, The polyolefin layer constitutes the surface on one side of the laminated film, The laminated film is a laminated film for a bipolar lithium ion battery, which is disposed so as to straddle a ridge line portion from the main surface to the side surface of the outer surface of the bipolar lithium ion battery. Item 2. The laminated film for a bipolar lithium ion battery according to Item 1, wherein the polyolefin layer contains polypropylene. Item 3. The laminated film for a bipolar lithium ion battery according to Item 1 or 2, wherein the polyolefin layer contains an acid-modified polyolefin. Item 4. The laminated film for a bipolar lithium ion battery according to any one of Items 1 to 3, wherein the polyolefin layer is formed of two or more layers of the same or different resins. Item 5. The laminated film for a bipolar lithium ion battery according to any one of Items 1 to 4, wherein the melting point of the polyolefin layer is 120°C or higher and 165°C or lower. Item 6. The laminated film for a bipolar lithium ion battery according to any one of Items 1 to 5, wherein the thickness of the polyolefin layer is 50 μm or more. Item 7. The laminated film for a bipolar lithium ion battery according to any one of Items 1 to 6, wherein the barrier layer is an aluminum alloy foil. Item 8. The laminated film for a bipolar lithium ion battery according to Item 7, wherein the aluminum alloy foil is an aluminum alloy foil having an iron content of 0.1% by mass or more and 9.0% by mass or less. Item 9. The laminated film for a bipolar lithium ion battery according to any one of Items 1 to 8, wherein the thickness of the barrier layer is 35 μm or more. Item 10. The laminated film for a bipolar lithium ion battery according to any one of Items 1 to 9, further comprising an adhesive layer between the barrier layer and the polyolefin layer. Item 11. The laminated film for a bipolar lithium ion battery according to Item 10, wherein the adhesive layer is formed of an adhesive containing polyolefin. Item 12. The laminated film for a bipolar lithium ion battery according to any one of Items 1 to 11, which is used by arranging a plurality of the laminated films on a part of the outer surface of the bipolar lithium ion battery. Item 13. The laminated film for a bipolar lithium ion battery according to any one of Items 1 to 12, further comprising at least one resin layer on the side of the barrier layer opposite to the polyolefin layer side.

Explanation of Reference Numerals

[0135] 1 Barrier layer 2 Polyolefin layer 3 Resin layer 4 Adhesive layer 5 Adhesive layer 10 Laminated film for bipolar lithium-ion battery 10a Laminated film for bipolar lithium-ion battery 10b Laminated film for bipolar lithium-ion battery 10c Laminated film for bipolar lithium-ion battery 10d Laminated film for bipolar lithium-ion battery 20 Bipolar lithium-ion battery 20a Main surface 20b Side surface 20c Ridge part 21 End collector 22 Collector 23 Positive electrode layer 24 Negative electrode layer 25 Electrolyte 26 Sealing member

Claims

1. A laminated film disposed on a part of the outer surface of a bipolar lithium-ion battery, wherein the laminated film comprises at least a barrier layer and a polyolefin layer provided on one side of the barrier layer, and the polyolefin layer constitutes the surface on one side of the laminated film, wherein the laminated film is disposed so as to straddle a ridge line portion from the main surface to the side surface of the outer surface of the bipolar lithium-ion battery, a laminated film for a bipolar lithium-ion battery.

2. The laminated film for a bipolar lithium-ion battery according to claim 1, wherein the polyolefin layer contains polypropylene.

3. The laminated film for a bipolar lithium-ion battery according to claim 1 or 2, wherein the polyolefin layer contains an acid-modified polyolefin.

4. The laminated film for a bipolar lithium-ion battery according to claim 1 or 2, wherein the polyolefin layer is formed of two or more layers of the same or different resins.

5. The laminated film for a bipolar lithium-ion battery according to claim 1 or 2, wherein the melting point of the polyolefin layer is 120°C or higher and 165°C or lower.

6. The laminated film for a bipolar lithium-ion battery according to claim 1 or 2, wherein the thickness of the polyolefin layer is 50 μm or more.

7. The laminated film for a bipolar lithium-ion battery according to claim 1 or 2, wherein the barrier layer is an aluminum alloy foil.

8. The laminated film for a bipolar lithium-ion battery according to claim 7, wherein the aluminum alloy foil is an aluminum alloy foil having an iron content of 0.1% by mass or more and 9.0% by mass or less.

9. The laminated film for a bipolar lithium-ion battery according to claim 1 or 2, wherein the thickness of the barrier layer is 35 μm or more.

10. The laminated film for a bipolar lithium-ion battery according to claim 1 or 2, further comprising an adhesive layer between the barrier layer and the polyolefin layer.

11. The laminated film for a bipolar lithium-ion battery according to claim 10, wherein the adhesive layer is formed of an adhesive containing polyolefin.

12. The laminated film for a bipolar lithium-ion battery according to claim 1 or 2, wherein a plurality of the laminated films are used by being disposed on a part of the outer surface of the bipolar lithium-ion battery.

13. The laminated film for a bipolar lithium ion battery according to claim 1 or 2, further comprising at least one resin layer on the side opposite to the polyolefin layer side of the barrier layer.

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