Energy storage device, electric vehicle, packaging material for energy storage device, container for energy storage device, and method for manufacturing the same.

Abstract

To provide a lightweight power storage device, an electric vehicle including the same, packaging material for the power storage device, a container for the power storage device, and a manufacturing method for the same.SOLUTION: In a power storage device 10 where an energy storage member 20 is enclosed within a packaging container 30, the packaging container 30 has a cylindrical body portion 31 having both axial ends open, formed by connecting one end portion and another end portion of a laminated film 40 via a connection portion 35, and a metal closure portion 36 that closes both axial ends of the body portion 31. The laminated film 40 is formed by sequentially laminating, from the outer surface side, a base material layer 41, a barrier layer 42, and a heat-sealable resin layer 43, and the heat-sealable resin layer 43 has acid-modified polypropylene as its innermost surface, and the body portion 31 is heat-sealed to the outer surface of the closure portion 36 by the heat-sealable resin layer 43.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a power storage device sealed by a packaging container and an electric vehicle equipped with the same. The present invention also relates to a packaging material for a power storage device, a packaging container for a power storage device using the same, and a method for manufacturing the same.

Background Art

[0002] In recent years, from the viewpoints of environmental measures and resource conservation, electric vehicles in which at least part of the driving force is supplied by a motor have attracted attention. Such electric vehicles include electric vehicles (EVs), hybrid vehicles (HEVs), plug-in hybrid vehicles (PHEVs), and the like. An electric vehicle uses only a motor as a power source, and hybrid vehicles and plug-in hybrid vehicles use a motor and an engine as power sources. These electric vehicles are equipped with a power storage device for supplying power to the motor.

[0003] Moreover, not only electric vehicles but also electric products driven by a motor such as aircraft, ships, personal mobility devices, and robots are equipped with a power storage device for supplying power to the motor.

[0004] A conventional power storage device mounted on an electric vehicle or the like is disclosed in Patent Document 1. This power storage device is arranged in parallel in a plurality by series connection and parallel connection, and is installed under the floor of an electric vehicle or the like. The power storage device includes a plurality of single cells made of secondary batteries, and is covered with a packaging container in a state where the positive electrode and the negative electrode are drawn out. The packaging container is formed of a metal can such as an aluminum alloy, and is sealed by a cylindrical body portion and a lid member that closes both end faces of the body portion.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

[0006] However, the conventional energy storage devices described above had the problem of increasing the weight of the device due to the metal packaging.

[0007] The present invention aims to provide a lightweight energy storage device, an electric vehicle equipped with the same, packaging materials for the energy storage device, a container for the energy storage device, and a method for manufacturing the same. [Means for solving the problem]

[0008] To achieve the above objective, the present invention provides an energy storage device in which an energy storage member is sealed in a packaging container, wherein the packaging container has a body portion formed in a cylindrical shape with both ends open in the axial direction by connecting one end and the other end of a laminated film with a connecting portion, and a metal closing portion that closes both ends of the body portion in the axial direction, wherein the laminated film is formed by laminating a base material layer, a barrier layer and a heat-adhesive resin layer in order from the outer surface, and the heat-adhesive resin layer has acid-modified polypropylene on its innermost surface, and the body portion is heat-bonded to the outer surface of the closing portion by the heat-adhesive resin layer.

[0009] Furthermore, the present invention is characterized in that, in the energy storage device having the above configuration, the body portion has a rectangular cross-section perpendicular to the axial direction, and the connection portion is arranged on the short side of the cross-section.

[0010] Furthermore, the present invention is characterized in that, in the energy storage device having the above configuration, the body portion has scribed lines parallel to the axial direction provided on the laminated film, and is bent along the scribed lines to form a rectangular cross-section perpendicular to the axial direction.

[0011] Furthermore, the present invention is characterized in that, in the energy storage device having the above configuration, one end of the laminated film has a folded portion obtained by folding back the outer surface side so as to overlap the processed surface where the thickness direction has been removed, and the connecting portion is heat-bonded by overlapping the heat-adhesive resin layer of the other end of the laminated film onto the heat-adhesive resin layer on the outer surface side of the folded portion.

[0012] Furthermore, the present invention is characterized in that, in the energy storage device having the above configuration, the processed surface is formed by removing the laminated film on the outer side of the barrier layer.

[0013] Furthermore, the present invention is characterized in that, in the energy storage device having the above configuration, the connection portion has a cylindrical portion which is arranged with the end faces of the laminated film abutting together, and an outer tape which adheres to the outer surface of the cylindrical portion and covers the end face.

[0014] Furthermore, the present invention is characterized in that, in the energy storage device having the above configuration, the connection portion has an inner surface tape that adheres to the inner surface of the cylindrical portion and covers the end surface.

[0015] Furthermore, in the energy storage device having the above configuration, the present invention is characterized in that the surface of the inner surface tape opposite to the surface that adheres to the inner surface of the cylindrical portion is formed of acid-modified polypropylene.

[0016] Furthermore, in the energy storage device having the above configuration, the connection portion is formed by joining one end and the other end of the laminated film together.

[0017] Furthermore, the electric vehicle of the present invention is characterized by being equipped with an energy storage device having each of the above-described configurations.

[0018] Furthermore, the present invention relates to a packaging material for an energy storage device, which is formed in a cylindrical shape with both ends open in the axial direction by connecting one end of a laminated film with the other end of the laminated film, wherein the laminated film is formed by laminating a base layer, a barrier layer, and a heat-adhesive resin layer in order from the outer surface, and the heat-adhesive resin layer has acid-modified polypropylene on its innermost surface.

[0019] Furthermore, the present invention is characterized in that, in the packaging material for an energy storage device having the above configuration, the cross section perpendicular to the axial direction is formed in a rectangular shape, and the connecting portion is arranged on the short side of the cross section.

[0020] Further, the present invention relates to a packaging material for a power storage device having the above-described configuration, which has ruled lines parallel to the axial direction provided on the laminated film, and is bent on the ruled lines to form a rectangular cross-section perpendicular to the axial direction.

[0021] The packaging container for a power storage device of the present invention includes a body portion formed of the packaging material for a power storage device having the above-described configuration, and a metal closing portion that closes both ends of the body portion. In the packaging container for a power storage device that encloses a power storage member, the body portion is thermally adhered to the outer surface of the closing portion by the thermally adhesive resin layer.

[0022] In a method for manufacturing a packaging container for a power storage device that encloses a power storage member, a step of connecting one end portion and the other end portion of the laminated film by a connecting portion to form a cylindrical body portion having both axial ends open; a step of closing both axial ends of the body portion with metal closing portions; The method for manufacturing a packaging container for a power storage device is characterized in that the laminated film is formed by laminating a base material layer, a barrier layer, and a thermally adhesive resin layer in this order from the outer surface side, the thermally adhesive resin layer has acid-modified polypropylene on the innermost surface, and the body portion is thermally adhered to the outer surface of the closing portion by the thermally adhesive resin layer to close the body portion.

Advantages of the Invention

[0023] According to the present invention, since the body portion of the packaging container is formed of a laminated film, the weight of the power storage device can be reduced, and the running cost of an electric product equipped with the power storage device can be lowered. Further, since acid-modified polypropylene is disposed on the innermost surface of the laminated film forming the body portion, the space between the metal closing portion and the body portion can be sealed. Therefore, the water vapor barrier property of the power storage device is improved, the characteristics of the power storage device can be maintained for a long time, and the long life of the power storage device can be achieved.

Brief Description of the Drawings

[0024] [Figure 1]Side view showing an electric vehicle equipped with the power storage device of the first embodiment of the present invention [Figure 2] Top view showing an electric vehicle equipped with the power storage device of the first embodiment of the present invention [Figure 3] Perspective view showing the power storage device of the first embodiment of the present invention [Figure 4] Top cross-sectional view showing the power storage device of the first embodiment of the present invention [Figure 5] Front cross-sectional view showing the power storage device of the first embodiment of the present invention [Figure 6] Detailed view of part G in FIG. 5 [Figure 7] Perspective view showing the power storage device of the second embodiment of the present invention [Figure 8] Front cross-sectional view showing the power storage device of the second embodiment of the present invention [Figure 9] Detailed view of part H in FIG. 8 [Figure 10] Front cross-sectional view showing the power storage device of the third embodiment of the present invention

Mode for Carrying Out the Invention

[0025] <First Embodiment> Embodiments of the present invention will be described below with reference to the drawings. FIGS. 1 and 2 show a side view and a top view of an electric vehicle 1 equipped with a power storage device 10 according to the first embodiment. The electric vehicle 1 includes a drive motor 3 as a power source for driving the wheels 2. A power storage device 10 is installed under the floor of the vehicle body of the electric vehicle 1 as a drive source for supplying power to the drive motor 3. The power storage device 10 may be installed on the roof of the electric vehicle 1 or in the seat.

[0026] Figures 3, 4, and 5 show a perspective view, a top cross-sectional view, and a front cross-sectional view of the energy storage device 10. The energy storage device 10 is formed by sealing an energy storage member 20 in a packaging container 30. The energy storage member 20 is formed by an energy storage element 21 in which a plurality of positive electrode plates and negative electrode plates are stacked in order with an insulating separator in between. An electrolyte is placed between the positive electrode plate and the negative electrode plate. In this embodiment, the electrolyte consists of an electrolyte solution. A solid electrolyte may also be used as the electrolyte. Metal lead terminals 27 and 28 are connected to the positive electrode plate and the negative electrode plate, respectively.

[0027] The packaging container 30 (packaging container for energy storage devices) has a cylindrical body portion 31 (packaging material for energy storage devices) formed with both ends open in the axial direction, and closing portions 36 that close both ends of the body portion 31 in the axial direction. The closing portions 36 are made of a metal block such as aluminum alloy, stainless steel, or titanium, and have a rectangular cross-section perpendicular to the axial direction. Electrodes 37 and 38 are integrally formed in the closing portions 36, and lead terminals 27 and 28 are connected to them.

[0028] The body portion 31 is formed from a laminated film 40 (see Figure 6), and one end of the laminated film 40 is connected to the other end by a connecting portion 35 to form a cylindrical shape. The cylindrical body portion 31 is heat-bonded to the outer surface of the closure portion 36, and a rectangular cross-section perpendicular to the axial direction is formed along the closure portion 36.

[0029] The connecting portion 35 extends axially from the body portion 31 and is provided on the short side of the rectangular cross-section. Here, the connecting portion 35 bulges because two laminated films 40 overlap, and this bulging portion is provided on the short side of the rectangular cross-section. Multiple energy storage devices 10 are arranged side by side with the connecting portion 35 on the upper or lower surface, so that the long sides of the rectangular cross-sections overlap, and are mounted on the electric vehicle 1. This eliminates the bulge of the connecting portion 35 in the direction in which the energy storage devices 10 are arranged side by side. As a result, it becomes possible to arrange multiple energy storage devices 10 side by side without gaps, and a decrease in volumetric efficiency can be prevented.

[0030] The laminated film 40 is provided with four scribing lines (not shown) extending in the axial direction, and by bending the laminated film 40 along the scribing lines, the body portion 31 can be brought into close contact with the rectangular cross-section closing portion 36. The radius of curvature of the cross-section of the scribing lines should be R2 or less, and a smaller radius is preferable. It is desirable to create the scribing lines by applying a temperature of 200°C or less for a time of 10 seconds or less, but even at room temperature or for a short time, the dimensions of the scribing line receiving mold and the applied pressure can be appropriately adjusted according to the required accuracy.

[0031] Furthermore, the rectangular-sectioned closed portion 36 may have curved surfaces with small radii at each corner. In this case, by providing multiple scribed lines extending in the axial direction on the laminated film 40 corresponding to each corner, the body portion 31 can be made to adhere closely to the corners of the curved surfaces of the closed portion 36.

[0032] Figure 6 shows a detailed view of section G in Figure 5. The laminated film 40 forming the body 31 has, in order from the outer surface, a base layer 41, a barrier layer 42, and a heat-adhesive resin layer 43.

[0033] The base layer 41 is formed from a resin film such as nylon (PA), polyethylene terephthalate (PET), or polypropylene (PP). To improve pinhole resistance, insulation, etc., the base layer 41 may be formed by laminating multiple resin films of different materials, such as nylon and polyethylene terephthalate. The thickness of the base layer 41 is, for example, 5 to 1000 μm, preferably 5 to 30 μm.

[0034] The barrier layer 42 is formed from an oxide vapor-deposited film (silica, alumina, etc.), a metal vapor-deposited film (aluminum, etc.), or a metal foil (aluminum, aluminum alloy, stainless steel, titanium, etc.). The barrier layer 42 prevents water vapor from entering the packaging container 30. The thickness of the vapor-deposited barrier layer 42 is, for example, several nanometers to several micrometers. The thickness of the metal foil barrier layer 42 is, for example, 5 to 1000 micrometers, preferably 10 to 200 micrometers.

[0035] The heat-adhesive resin layer 43 is formed from acid-modified polypropylene and heat-bonded to the outer surface of the occlusion portion 36. The base layer 41 and the heat-adhesive resin layer 43 are formed on a metal foil barrier layer 42 or on a film with a vapor-deposited barrier layer 42 by dry lamination or extrusion lamination. The thickness of the heat-adhesive resin layer 43 is, for example, 10 to 200 μm.

[0036] By forming the heat-adhesive resin layer 43 with acid-modified polypropylene, the space between the metal closure portion 36 and the body portion 31 made of laminated film 40 can be sealed. This prevents water vapor from entering through the gap between the body portion 31 and the closure portion 36. As the acid-modified polypropylene, polypropylene modified with a carboxylic acid or its anhydride, maleic anhydride-modified polypropylene, etc., can be used.

[0037] The heat-adhesive resin layer 43 is formed from a single layer of acid-modified polypropylene, but it may be formed from two or more layers laminated with a different resin, as long as the innermost layer is acid-modified polypropylene. As a resin other than acid-modified polypropylene, linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), acid-modified polyethylene, polypropylene (PP), acid-modified polypropylene, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), etc. can be used.

[0038] The thickness of the laminated film 40 is, for example, 20 to 1200 μm, preferably 20 to 300 μm.

[0039] A folded portion 46 is provided at one end of the laminated film 40. Specifically, one end of the laminated film 40 is formed by removing material from the outer surface in the thickness direction to create a stepped portion 47, and the laminated film 40 is folded back so that the removed processed surface 47a (the outer surface of the stepped portion 47) overlaps. The stepped portion 47 is formed by dry etching, wet etching, cutting, etc. As a result, a heat-adhesive resin layer 43 is placed on the outer surface of one end of the laminated film 40 and heat-bonded to the heat-adhesive resin layer 43 on the inner surface of the other end. At this time, the processed surface 47a that is folded back and overlapped is bonded by heat and pressure, but it may also be bonded with an adhesive such as epoxy, acrylic, or polyester.

[0040] Accordingly, the manufacturing process for the packaging container 30 comprises a folded portion forming step, a body forming step, and a closing step. In the folded portion forming step, the outer surface of one end of the laminated film 40 is removed in the thickness direction, and the removed processed surface 47a is folded back so that it overlaps to form a folded portion 46. In the body forming step, the heat-adhesive resin layer 43 on the outer surface of the folded portion 46 and the heat-adhesive resin layer 43 on the other end of the laminated film 40 are overlapped and heat-bonded. This connects one end of the laminated film 40 to the other end with a connecting portion 35 to form a cylindrical body 31. In the closing step, the laminated film 40 is heat-bonded to the outer surface of a metal closing portion 36 with the heat-adhesive resin layer 43, and both axial ends of the body 31 are closed by the closing portion 36.

[0041] This ensures that the laminated film 40 is securely sealed into an envelope by the opposing heat-adhesive resin layer 43, thereby sealing the packaging container 30. At this time, only the outer end surface of the laminated film 40 is exposed at the sealing portion of the cylindrical body 31. As a result, the intrusion of water vapor into the energy storage device 10 and the volatilization of the electrolyte of the energy storage component 20 are suppressed. Consequently, the water vapor barrier properties of the energy storage device 10 are improved, allowing the characteristics of the energy storage device 10 to be maintained for a long period of time, thereby dramatically increasing the lifespan of the energy storage device 10 and extending its lifespan.

[0042] Furthermore, the laminated film 40 on the outer side of the barrier layer 42 is removed to form the processed surface 47a, leaving the folded barrier layer 52 within the folded portion 46. This further suppresses the deterioration of the barrier properties of the packaging container 30.

[0043] In addition, since the barrier layer 42 is not exposed to the inner surface of the packaging container 30, short circuits of the energy storage member 20 can be prevented when the barrier layer 42 is formed from metal foil or a metal vapor-deposited film.

[0044] According to this embodiment, since the body 31 of the packaging container 30 is formed from a laminated film 40, the energy storage device 10 can be made lighter. This improves the energy efficiency of electric vehicles equipped with the energy storage device 10. Furthermore, since acid-modified polypropylene is placed on the innermost surface of the laminated film 40 forming the body 31, the space between the metal closure 36 and the body 31 can be sealed. As a result, the intrusion of water vapor into the energy storage device 10 and the volatilization of the electrolyte of the energy storage member 20 are suppressed. Consequently, the water vapor barrier properties of the energy storage device 10 are improved, the characteristics of the energy storage device 10 can be maintained for a long period of time, and the lifespan of the energy storage device 10 can be extended.

[0045] Furthermore, since the connection portion 35 is located on the short side of the rectangular cross-section of the body portion 31, it is possible to prevent a decrease in volumetric efficiency when multiple energy storage devices 10 are installed side by side in an electric vehicle 1.

[0046] Furthermore, since the body portion 31 has creases parallel to the axial direction provided on the laminated film 40, and is bent along these creases to form a rectangular cross-section perpendicular to the axial direction, the space between the body portion 31 and the closing portion 36 can be sealed more reliably. Accordingly, the water vapor barrier properties of the energy storage device 10 can be further improved.

[0047] Furthermore, the body portion 31 has a folded portion 46 formed by folding back the outer surface of one end of the laminated film 40 so that the processed surface 47a, which has been removed in the thickness direction, overlaps with the folded portion 46. Then, the heat-adhesive resin layer 43 of the other end of the laminated film 40 is superimposed on the heat-adhesive resin layer 43 on the outer surface of the folded portion 46 and heat-bonded. This reduces the exposed area of ​​the heat-adhesive resin layer 43, thereby suppressing the intrusion of water vapor into the energy storage device 10 and the volatilization of the electrolyte of the energy storage member 20. Consequently, the water vapor barrier properties of the energy storage device 10 can be further improved.

[0048] Furthermore, since the processed surface 47a is formed by removing the laminated film 40 on the outer side of the barrier layer 42, the metal foil or metal vapor-deposited film barrier layer 42 is not exposed on the inner side of the packaging container 30, thus preventing a short circuit of the energy storage member 20.

[0049] Furthermore, the manufacturing method of the packaging container 30 involves sealing the body portion 31 by heat-bonding it to the outer surface of a metal closure portion 36 using a heat-adhesive resin layer 43 having acid-modified polypropylene on its innermost surface. This makes it possible to reduce the weight of the energy storage device and improve its water vapor barrier properties, thereby extending the lifespan of the energy storage device.

[0050] In this embodiment, if the effect of property degradation due to the exposure of the end face of the laminated film 40 is small, the laminated film 40 may be sealed in an envelope shape without providing the folded portion 46 when forming the body portion 31. In that case, the connecting portion 30 will be joined by directly overlapping the heat-adhesive resin layer 43 of the other end of the laminated film 40 with the base material layer 41 of one end of the laminated film 40. For this reason, when joining by heat bonding, the base material layer 41 of the laminated film 40 is formed of a resin that can adhere to acid-modified polypropylene, which is the heat-adhesive resin layer 43.

[0051] <Second Embodiment> Next, Figures 7 and 8 show a perspective view and a front cross-sectional view of the energy storage device 10 of the second embodiment. For convenience of explanation, the same reference numerals are used for parts that are the same as those in the first embodiment shown in Figures 1 to 6 above. The configuration of the connection part 35 in this embodiment differs from that of the first embodiment. The other parts are the same as in the first embodiment.

[0052] The body portion 31 is connected to one end of the laminated film 40 (see Figure 9) by a connecting portion 35, which has a cylindrical portion 32, an outer tape 33, and an inner tape 34. The cylindrical portion 32 is formed by butting the end faces S of the laminated film 40 (see Figure 9) together to form a cylinder. The outer tape 33 adheres to the outer surface of the cylindrical portion 32 and covers the butted end faces S of the cylindrical portion 32. The inner tape 34 adheres to the inner surface of the cylindrical portion 32 and covers the butted end faces S of the cylindrical portion 32. The outer tape 33 and the inner tape 34 prevent water vapor from entering the packaging container 30 through the gap between the opposing end faces S of the cylindrical portion 32.

[0053] Figure 9 shows a detailed view of section H in Figure 8. The cylindrical section 32 is arranged with the end faces S of the laminated film 40 butted together, and, similar to the first embodiment, has a base layer 41, a barrier layer 42, and a heat-adhesive resin layer 43 in order from the outer surface. Acid-modified polypropylene is placed on the innermost surface of the heat-adhesive resin layer 43.

[0054] The outer tape 33 is formed from a laminated film 50 and has, in order from the outer side, a base layer 51, a barrier layer 52, and an adhesive layer 53. The base layer 51 is formed from a resin film such as linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP), acid-modified polypropylene, acid-modified polyethylene, polyethylene terephthalate (PET), or polybutylene terephthalate (PBT). The thickness of the base layer 51 is, for example, 5 to 1000 μm.

[0055] The barrier layer 52 is formed from an oxide vapor-deposited film (silica, alumina, etc.), a metal vapor-deposited film (aluminum, etc.), or a metal foil (aluminum, aluminum alloy, stainless steel, titanium, etc.). The barrier layer 52 prevents water vapor from entering the packaging container 30 from the outer tape 33. The thickness of the vapor-deposited barrier layer 52 is, for example, several nanometers to several micrometers. The thickness of the metal foil barrier layer 52 is, for example, 5 to 1000 micrometers, preferably 10 to 200 micrometers.

[0056] The adhesive layer 53 is formed from linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP), acid-modified polypropylene, acid-modified polyethylene, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), etc. The thickness of the adhesive layer 53 is, for example, 5 to 100 μm. The base layer 51 and the adhesive layer 53 are formed on a metal foil barrier layer 52 or on a film with a vapor-deposited barrier layer 52 by dry lamination or extrusion lamination.

[0057] The thickness of the outer tape 33 is, for example, 10 to 1000 μm, preferably 10 to 100 μm.

[0058] By placing the outer tape 33 so as to cover the opposing end faces S of the cylindrical portion 32 and then heating and pressing it, the outer tape 33 is bonded to the cylindrical portion 32 by the adhesive layer 53. This prevents the end faces S of the laminated film 40 from being exposed.

[0059] Furthermore, the adhesive layer 53 can be made from linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP), acid-modified polypropylene, acid-modified polyethylene, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), etc., which are used as heat-adhesive resins.

[0060] Among these, using resins with high water vapor barrier properties, such as linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP), acid-modified polypropylene, and acid-modified polyethylene, suppresses the penetration of water vapor into the packaging container 30 via the adhesive layer 53, thereby maintaining the characteristics of the energy storage device 10 for a long period of time. Note that adhesives such as urethane-based, epoxy-based, acrylic-based, and polyester-based adhesives may also be used as the adhesive layer 53.

[0061] The inner tape 34 is formed from a laminated film 60 and has, in order from the inner side, a base layer 61, a barrier layer 62, and an adhesive layer 63. The adhesive layer 63 adheres the inner tape 34 to the inner surface of the cylindrical portion 32. The base layer 61 is also adhered to the circumferential surface of the closure portion 36.

[0062] The base layer 61 is formed from a resin film such as linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP), acid-modified polypropylene, acid-modified polyethylene, polyethylene terephthalate (PET), or polybutylene terephthalate (PBT). The thickness of the base layer 41 is, for example, 5 to 100 μm.

[0063] It is more desirable to provide acid-modified polypropylene on the innermost surface of the base layer 61 (the surface opposite to the surface that adheres to the inner surface of the cylindrical portion 32 of the inner tape 34). This allows for a seal between the inner tape 34 and the closure portion 36 (see Figure 7).

[0064] The barrier layer 62 is formed from an oxide vapor-deposited film (silica, alumina, etc.), a metal vapor-deposited film (aluminum, etc.), or a metal foil (aluminum, aluminum alloy, stainless steel, titanium, etc.). The barrier layer 62 can more effectively prevent water vapor from entering the packaging container 30 through the gap between the end faces S. The thickness of the vapor-deposited barrier layer 62 is, for example, several nm to several μm. The thickness of the metal foil barrier layer 62 is, for example, 5 to 1000 μm, preferably 10 to 200 μm.

[0065] The adhesive layer 63 is formed from linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP), acid-modified polypropylene, acid-modified polyethylene, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), etc. The thickness of the adhesive layer 63 is, for example, 10 to 100 μm. The base layer 61 and the adhesive layer 63 are formed on a metal foil barrier layer 62 or on a film with a vapor-deposited barrier layer 62 by dry lamination or extrusion lamination.

[0066] The thickness of the inner tape 34 is, for example, 10 to 1000 μm, preferably 10 to 100 μm.

[0067] The inner tape 34 is placed so as to cover the opposing end faces S of the cylindrical portion 32 and then heat-pressed to adhere it to the cylindrical portion 32 by the adhesive layer 63. An adhesive such as urethane, epoxy, acrylic, or polyester may be used as the adhesive layer 63.

[0068] Here, if the barrier layer 62 is formed from a metal foil or a metal vapor-deposited film and is exposed on the side end surface of the inner tape 34, there is a risk of short-circuiting the energy storage member 20. For this reason, as shown in Figure 9, the barrier layer 62 is formed with a narrower circumferential width relative to the base layer 61 and the adhesive layer 63 by etching the inner tape 34 or the like. As a result, the side end surface of the barrier layer 62 is covered by the base layer 61 and the adhesive layer 63, and no metal is exposed on the end surface of the inner tape 34, thus preventing short-circuiting of the energy storage member 20.

[0069] Furthermore, if the outer tape 33 can sufficiently block water vapor, the barrier layer 62 may be omitted and an inner tape 34 having an adhesive layer 63 may be used instead. Moreover, if the outer tape 33 can block water vapor to an even higher level, the inner tape 34 may be omitted.

[0070] According to this embodiment, similar to the first embodiment, the body 31 of the packaging container 30 is formed from a laminated film 40, which makes it possible to reduce the weight of the energy storage device 10. Furthermore, since acid-modified polypropylene is placed on the innermost surface of the laminated film 40, the water vapor barrier properties of the energy storage device 10 are improved, which makes it possible to extend the lifespan of the energy storage device 10.

[0071] Furthermore, the packaging container 30 is formed by adhering an outer tape 33 to the outer surface of a cylindrical portion 32 where the end faces S of the laminated film 40 are joined together. This reduces the exposed area of ​​the heat-adhesive resin layer 43 of the laminated film 40 forming the cylindrical portion 32, and covers the gap between the end faces S of the laminated film 40 with the outer tape 33. As a result, the intrusion of water vapor into the energy storage device 10 and the volatilization of the electrolyte of the energy storage member 20 can be further suppressed.

[0072] Furthermore, since the inner surface tape 34, which has a resin adhesive layer 63 on its outer surface, is adhered to the inner surface of the cylindrical portion 32, the gap between the end faces S of the cylindrical portion 32 is shielded by the inner surface tape 34. Therefore, the intrusion of water vapor into the energy storage device 10 and the volatilization of the electrolyte of the energy storage member 20 can be further suppressed.

[0073] Furthermore, since the side of the inner tape 34 opposite to the side that adheres to the inner surface of the cylindrical portion 32 is made of acid-modified polypropylene, the space between the body portion 31 and the closure portion 36 can be sealed more reliably.

[0074] <Third Embodiment> Next, Figure 10 shows a front cross-sectional view of the energy storage device 10 of the third embodiment. For convenience of explanation, the same reference numerals are used for parts that are the same as those in the first embodiment shown in Figures 1 to 6 above. The configuration of the connection part 35 in this embodiment differs from that of the first embodiment. The other parts are the same as in the first embodiment.

[0075] The body portion 31 is connected to one end and the other end of the laminated film 40 (see Figure 9) by a connecting portion 35. The connecting portion 35 joins the opposing heat-adhesive resin layers 43 of the one end and the other end of the laminated film 40 together. The connecting portion 35 extends in the axial direction of the body portion 31 and is provided on the short side of the rectangular cross-section of the body portion 31.

[0076] According to this embodiment, similar to the first embodiment, the body 31 of the packaging container 30 is formed from a laminated film 40, which makes it possible to reduce the weight of the energy storage device 10. Furthermore, since acid-modified polypropylene is placed on the innermost surface of the laminated film 40, the water vapor barrier properties of the energy storage device 10 are improved, which makes it possible to extend the lifespan of the energy storage device 10.

[0077] Furthermore, since the connecting portion 35 is formed by joining one end and the other end of the laminated film 40 together, a lightweight energy storage device 10 can be easily realized.

[0078] Furthermore, the energy storage devices 10 of the first and second embodiments are more desirable because, compared to this embodiment in which the connection portion 35 is glued together, the barrier properties of the packaging container 30 are higher, thus extending the lifespan of the energy storage device 10.

[0079] In the first to third embodiments, the energy storage member 20 may be a bipolar type in which a plurality of energy storage elements 21 are stacked and connected in series, and metal tabs provided on both end faces in the stacking direction are connected to electrodes 37 and 38. Also, although the energy storage member 20 that supplies power to the drive motor 3 consists of a secondary battery, it may also be a capacitor (electrolytic capacitor, electric double-layer capacitor, lithium-ion capacitor, etc.). [Industrial applicability]

[0080] According to the present invention, energy storage devices and electric vehicles equipped with such devices can be widely used. [Explanation of symbols]

[0081] 1 Electric vehicle 2 wheels 3. Drive motor 10 Energy storage devices 20 Energy storage components 21 Energy storage element 27, 28 Lead terminals 30 Packaging containers 31 Torso 32 Cylindrical part 33. Outer surface tape 34. Inner tape 35 Connection part 36 Occlusion 37, 38 electrode 40, 50, 60 laminated film 41, 51, 61 Base layer 42, 52, 62 Barrier layer 43 Heat adhesive resin layer 46 Folded section 47 Stepped section 47 47a Machined surface 53, 63 Adhesive layer S end face

Claims

1. comprising multiple energy storage devices, Each of the aforementioned energy storage devices is an energy storage device in which an energy storage member is sealed in a packaging container, wherein the packaging container has a body portion formed in a cylindrical shape with both ends open in the axial direction by connecting one end and the other end of a laminated film with a connecting portion, and a metal closing portion that closes both ends of the body portion in the axial direction, wherein the laminated film is formed by laminating a base layer, a barrier layer, and a heat-adhesive resin layer in order from the outer surface, and the heat-adhesive resin layer has acid-modified polypropylene on its innermost surface, and the body portion is heat-bonded to the outer surface of the closing portion by the heat-adhesive resin layer, The body portion is formed with a rectangular cross-section perpendicular to the axial direction, and the connecting portion is positioned on the short side of the cross-section. An assembly of energy storage devices in which the plurality of energy storage devices are arranged side by side so that the longer sides of the rectangular cross-sections overlap, with the connection portion positioned on the upper or lower surface.

2. The energy storage device assembly according to claim 1, characterized in that one end of the laminated film has a folded portion obtained by folding back the outer surface side such that the processed surface removed in the thickness direction overlaps, and the connecting portion is heat-bonded by overlapping the heat-adhesive resin layer of the other end of the laminated film onto the heat-adhesive resin layer on the outer surface side of the folded portion.

3. The energy storage device assembly according to claim 2, characterized in that the processed surface is formed by removing the laminated film on the outer side of the barrier layer.

4. The energy storage device assembly according to claim 1, characterized in that the connecting portion has a cylindrical portion which is arranged with the end faces of the laminated film abutting together, and an outer tape which is adhered to the outer surface of the cylindrical portion and covers the end faces.

5. The energy storage device assembly according to claim 4, characterized in that the connecting portion has an inner surface tape that adheres to the inner surface of the cylindrical portion and covers the end surface.

6. The energy storage device assembly according to claim 5, characterized in that the surface of the inner surface tape opposite to the surface that adheres to the inner surface of the cylindrical portion is made of acid-modified polypropylene.

7. The energy storage device assembly according to claim 1, characterized in that the connecting portion is formed by joining one end and the other end of the laminated film together.

8. An electric vehicle characterized by comprising an energy storage device assembly according to any one of claims 1 to 7.

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