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

[0002] In recent years, from the perspectives of environmental protection and resource conservation, attention has been focused on electric vehicles, in which at least part of the driving force is supplied by a motor. These electric vehicles include electric vehicles (EVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs). Electric vehicles are powered solely by a motor, while hybrid electric vehicles and plug-in hybrid electric vehicles are powered by both a motor and an engine. These electric vehicles are equipped with an electricity storage device to supply electricity to the motor.

[0003] Furthermore, power storage devices for supplying power to motors are mounted not only in electric vehicles but also in motor-driven electric products such as aircraft, ships, personal mobility vehicles, and robots.

[0004] A conventional power storage device mounted on an electric vehicle or the like is disclosed in Patent Document 1. A plurality of such power storage devices are arranged in series and parallel connections and are installed under the floor of the electric vehicle or the like. The power storage device includes a plurality of secondary battery cells, and is covered by a packaging container with the positive and negative electrodes pulled out. The packaging container is formed from a metal can or the like made of an aluminum alloy, and is sealed by a cylindrical body and lids that close both end faces of the body. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2014-527270 (pages 5 to 8, Figure 1) Summary of the Invention [Problem to be solved by the invention]

[0006] However, the conventional electricity storage device has a problem in that the weight of the electricity storage device increases due to the metal packaging container.

[0007] An object of the present invention is to provide a lightweight electricity storage device, an electric vehicle equipped with the same, a packaging material for the electricity storage device, a container for the electricity storage device, and a method for manufacturing the same. [Means for solving the problem]

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

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

[0010] Furthermore, in the energy storage device of the present invention having the above-described configuration, the body portion has a line parallel to the axial direction provided on the laminated film, and is bent along the line 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-described configuration, one end of the laminated film has a folded portion that is folded back so as to overlap the processed surface that has been removed in the thickness direction on the outer surface side, and the connection portion is thermally bonded by overlapping the thermal adhesive resin layer at the other end of the laminated film on the thermal adhesive resin layer on the outer surface side of the folded portion.

[0012] In the electricity storage device of the present invention having the above-described configuration, the processed surface is formed by removing a portion of the laminated film outer than the barrier layer.

[0013] The present invention is also characterized in that, in the energy storage device having the above-described configuration, the connection portion has a tubular portion arranged so that the end faces of the laminated film are butted together, and an outer tape adhered to the outer surface of the tubular portion and covering the end faces.

[0014] In the electricity storage device of the present invention having the above-described configuration, the connecting portion has an inner surface tape that is adhered to the inner surface of the cylindrical portion and covers the end surface.

[0015] In the electricity storage device of the present invention having the above-described configuration, the surface of the inner surface tape opposite to the surface that is bonded to the inner surface of the tubular portion is formed of acid-modified polypropylene.

[0016] In the electricity storage device of the present invention having the above-described configuration, the connection portion is formed by joining one end and the other end of the laminated film together.

[0017] An electric vehicle according to the present invention is characterized by including an electricity storage device having any of the above configurations.

[0018] The present invention also provides a packaging material for an electricity storage device, which is formed into a tubular shape with both axial ends open by connecting one end and the other end of a laminated film with a connecting part, characterized in that the laminated film is formed by laminating, in order from the outer surface side, a base material layer, a barrier layer, and a thermal adhesive resin layer, and the thermal adhesive resin layer has acid-modified polypropylene on its innermost surface.

[0019] Furthermore, in the packaging material for an electricity storage device having the above-described configuration, the present invention is characterized in that a cross section perpendicular to the axial direction is formed into a rectangle, and the connection portion is disposed on a short side of the cross section.

[0020] The present invention is also characterized in that, in the packaging material for an electricity storage device having the above-mentioned configuration, the laminated film has a line parallel to the axial direction, and is folded along the line to form a rectangular cross section perpendicular to the axial direction.

[0021] The packaging container for an electricity storage device of the present invention also comprises a body formed from the packaging material for an electricity storage device having the above-described configuration, and metal closing portions that close both ends of the body, and is a packaging container for an electricity storage device that encloses an electricity storage member, characterized in that the body is thermally bonded to the outer surface of the closing portion by the thermal adhesive resin layer.

[0022] A method for manufacturing a packaging container for an electricity storage device that encloses an electricity storage member, comprising: a step of connecting one end and the other end of the laminated film with a connecting portion to form a cylindrical body portion having both axial ends open; a step of closing both ends of the body portion in the axial direction with metal closing portions; the laminated film is formed by laminating, in order from the outer surface side, a base material layer, a barrier layer, and a thermal adhesive resin layer, the thermal adhesive resin layer having an acid-modified polypropylene on its innermost surface, and the body portion is closed by the thermal adhesive resin layer thermally bonding the body portion to the outer surface of the closing portion. [Effects of the Invention]

[0023] According to the present invention, the body of the packaging container is formed from a laminated film, which allows for a reduction in the weight of the electricity storage device and reduces the running costs of electric appliances equipped with the electricity storage device. Furthermore, the acid-modified polypropylene is disposed on the innermost surface of the laminated film that forms the body, thereby providing a tight seal between the metal closing portion and the body. This improves the water vapor barrier properties of the electricity storage device, allowing the characteristics of the electricity storage device to be maintained for a long period of time, thereby extending the life of the electricity storage device. [Brief explanation of the drawings]

[0024] [Figure 1]FIG. 1 is a side view showing an electric vehicle equipped with an electricity storage device according to a first embodiment of the present invention; [Figure 2] FIG. 1 is a top view showing an electric vehicle equipped with an electricity storage device according to a first embodiment of the present invention; [Figure 3] FIG. 1 is a perspective view showing an electricity storage device according to a first embodiment of the present invention; [Figure 4] FIG. 1 is a top cross-sectional view showing an electricity storage device according to a first embodiment of the present invention; [Figure 5] FIG. 1 is a front cross-sectional view showing an electricity storage device according to a first embodiment of the present invention; [Figure 6] Detailed view of part G in Figure 5 [Figure 7] FIG. 10 is a perspective view showing an electricity storage device according to a second embodiment of the present invention; [Figure 8] FIG. 10 is a front cross-sectional view showing an electricity storage device according to a second embodiment of the present invention. [Figure 9] Detailed view of part H in Figure 8 [Figure 10] FIG. 10 is a front cross-sectional view showing an electricity storage device according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

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

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

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

[0028] The body 31 is formed from a laminated film 40 (see FIG. 6), and is formed into a cylindrical shape by connecting one end and the other end of the laminated film 40 with a connecting part 35. The cylindrical body 31 is heat-bonded to the outer surface of the closing part 36, and the cross section perpendicular to the axial direction is formed into a rectangle that follows the closing part 36.

[0029] The connection portion 35 extends in the axial direction of the body portion 31 and is provided on a short side of the rectangular cross section. Here, the connection portion 35 is bulged because two laminated films 40 are overlapped, and this bulged portion is provided on a short side of the rectangular cross section. A plurality of electricity storage devices 10 are mounted on the electric vehicle 1, with the connection portion 35 disposed on the upper or lower surface and arranged side by side so that the long sides of the rectangular cross section overlap. This makes it possible to eliminate bulges of the connection portion 35 in the direction in which the electricity storage devices 10 are arranged side by side. This makes it possible to arrange a plurality of electricity storage devices 10 side by side without any gaps, preventing a decrease in volumetric efficiency.

[0030] The laminated film 40 has four axially extending score lines (not shown), and by folding the laminated film 40 along the score lines, the trunk portion 31 can be tightly attached to the rectangular cross-section of the closure portion 36. The radius of curvature of the cross section of the score lines needs to be R2 or less, and the smaller the radius, the better. Furthermore, it is desirable to create the score lines at a temperature of 200°C or less for a time of 10 seconds or less, but the dimensions of the score line receiving die and pressure can be adjusted appropriately depending on the desired accuracy, even at room temperature or for a short time.

[0031] The rectangular cross-section of the closing portion 36 may have a curved surface with a small radius at each corner. In this case, by providing a plurality of axially extending lines corresponding to each corner on the laminated film 40, the body portion 31 can be tightly attached along the corners of the curved surface of the closing portion 36.

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

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

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

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

[0036] By forming the thermal adhesive resin layer 43 from acid-modified polypropylene, it is possible to seal the gap between the metal closing part 36 and the body part 31 made of the laminated film 40. This makes it possible to prevent water vapor from penetrating through the gap between the body part 31 and the closing part 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 thermal adhesive resin layer 43 is formed of a single layer of acid-modified polypropylene, but may be formed of two or more layers laminated with a different resin as long as the innermost layer is acid-modified polypropylene. Examples of resins that can be used other than acid-modified polypropylene include linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), acid-modified polyethylene, polypropylene (PP), acid-modified polypropylene, polyethylene terephthalate (PET), and polybutylene terephthalate (PBT).

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

[0039] A folded portion 46 is provided at one end of the laminate film 40. That is, one end of the laminate film 40 is formed by removing the outer surface side in the thickness direction to form a step portion 47, and is folded back so that a processed surface 47a (the outer surface of the step portion 47) from which the laminate film 40 has been removed is overlapped. The step portion 47 is formed by dry etching, wet etching, cutting, or the like. As a result, a thermally adhesive resin layer 43 is disposed on the outer surface of one end of the laminate film 40, and is thermally bonded to the thermally adhesive resin layer 43 on the inner surface of the other end. At this time, the folded and overlapped processed surface 47a is bonded by thermocompression, but it may also be bonded with an adhesive such as an epoxy, acrylic, or polyester adhesive.

[0040] Therefore, the manufacturing process for the packaging container 30 includes a folded portion forming step, a body portion forming step, and a closing step. In the folded portion forming step, the outer surface side of one end of the laminate film 40 is removed in the thickness direction, and the removed processed surface 47a is folded back so as to overlap to form the folded portion 46. In the body portion forming step, the thermal adhesive resin layer 43 on the outer surface of the folded portion 46 is overlapped and thermally bonded to the thermal adhesive resin layer 43 at the other end of the laminate film 40. As a result, one end and the other end of the laminate film 40 are connected by the connecting portion 35 to form the tubular body portion 31. In the closing step, the laminate film 40 is thermally bonded to the outer surface of the metal closing portion 36 by the thermal adhesive resin layer 43, and both axial ends of the body portion 31 are closed by the closing portion 36.

[0041] This allows the laminated film 40 to be reliably attached to the envelope by the opposing thermal adhesive resin layer 43, thereby sealing the packaging container 30. At this time, only the outer end face of the laminated film 40 is exposed at the seal portion of the cylindrical body 31. This prevents water vapor from penetrating into the electricity storage device 10 and prevents the electrolyte solution in the electricity storage member 20 from volatilizing. This improves the water vapor barrier properties of the electricity storage device 10, allowing the characteristics of the electricity storage device 10 to be maintained for a long period of time, thereby dramatically improving and extending the life of the electricity storage device 10.

[0042] Furthermore, the laminated film 40 on the outer side of the barrier layer 42 is removed to form the processed surface 47a, and the barrier layer 52 folded back remains within the folded-back portion 46. This makes it possible to further prevent the barrier properties of the packaging container 30 from deteriorating.

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

[0044] According to this embodiment, the body 31 of the packaging container 30 is formed from the laminated film 40, which allows the weight of the electricity storage device 10 to be reduced. This allows the electricity consumption of an electric vehicle equipped with the electricity storage device 10 to be improved. Furthermore, acid-modified polypropylene is disposed on the innermost surface of the laminated film 40 that forms the body 31, which allows a seal to be formed between the metal closing portion 36 and the body 31. This prevents water vapor from penetrating into the electricity storage device 10 and prevents the electrolyte solution in the electricity storage member 20 from volatilizing. This improves the water vapor barrier properties of the electricity storage device 10, allowing the characteristics of the electricity storage device 10 to be maintained for a long period of time, thereby extending the life of the electricity storage device 10.

[0045] Furthermore, since the connection portion 35 is disposed on a short side of the rectangular cross section of the body portion 31, it is possible to prevent a decrease in volumetric efficiency when a plurality of power storage devices 10 are arranged side by side and mounted on the electric vehicle 1.

[0046] Furthermore, the body 31 has creases parallel to the axial direction provided on the laminated film 40 and is folded along the creases to form a rectangular cross section perpendicular to the axial direction, so that the space between the body 31 and the closing portion 36 can be more reliably sealed. This can further improve the water vapor barrier properties of the electricity storage device 10.

[0047] The trunk portion 31 also has a folded portion 46 formed by folding back the outer surface of one end of the laminate film 40 so as to overlap a processed surface 47a that has been removed in the thickness direction. The thermal adhesive resin layer 43 at the other end of the laminate film 40 is then superimposed on and thermally bonded to the thermal adhesive resin layer 43 on the outer surface of the folded portion 46. This reduces the exposed area of ​​the thermal adhesive resin layer 43, thereby suppressing the intrusion of water vapor into the electricity storage device 10 and the volatilization of the electrolyte solution in the electricity storage member 20. This further improves the water vapor barrier property of the electricity storage device 10.

[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 barrier layer 42 of metal foil or metal vapor deposition film is not exposed on the inner side of the packaging container 30, thereby preventing short circuits of the storage member 20.

[0049] Furthermore, the manufacturing method of the packaging container 30 closes the body 31 by thermally bonding the body 31 to the outer surface of the metal closing part 36 with a thermal adhesive resin layer 43 having acid-modified polypropylene on the innermost surface. This makes it possible to reduce the weight of the electricity storage device, improve the water vapor barrier properties of the electricity storage device, and extend the life of the electricity storage device.

[0050] In this embodiment, if the effect of deterioration in characteristics due to exposure of the end face of the laminate film 40 is small, the laminate film 40 may be attached to an envelope without providing the folded portion 46 when forming the body portion 31. In this case, the connecting portion 30 is formed by directly overlapping and bonding the heat-adhesive resin layer 43 at one end of the laminate film 40 to the base material layer 41 at the other end of the laminate film 40. Therefore, when bonding by heat bonding, the base material layer 41 of the laminate film 40 is formed from a resin that can bond to the acid-modified polypropylene that is the heat-adhesive resin layer 43.

[0051] Second Embodiment Next, Fig. 7 and Fig. 8 show a perspective view and a front cross-sectional view of an electricity storage device 10 according to a second embodiment. For ease of explanation, the same parts as those in the first embodiment shown in Figs. 1 to 6 are denoted by the same reference numerals. This embodiment differs from the first embodiment in the configuration of the connection portion 35. The other parts are the same as those in the first embodiment.

[0052] The body portion 31 is connected to one end and the other end of the laminated film 40 (see FIG. 9) by a connecting portion 35, and the connecting portion 35 has a tubular portion 32, an outer tape 33, and an inner tape 34. The tubular portion 32 is arranged in a cylindrical shape with the end faces S of the laminated film 40 (see FIG. 9) butted together. The outer tape 33 is adhered to the outer surface of the tubular portion 32 and covers the butted end faces S of the tubular portion 32. The inner tape 34 is adhered to the inner surface of the tubular portion 32 and covers the butted end faces S of the tubular portion 32. The outer tape 33 and the inner tape 34 prevent water vapor from penetrating into the packaging container 30 through the gap between the opposing end faces S of the tubular portion 32.

[0053] Fig. 9 shows a detailed view of part H in Fig. 8. The cylindrical part 32 is arranged with the end face S of the laminated film 40 butting against each other, and has, from the outer surface side, a base material layer 41, a barrier layer 42, and a thermal adhesive resin layer 43, in that order, as in the first embodiment. An acid-modified polypropylene is arranged on the innermost surface of the thermal adhesive resin layer 43.

[0054] The outer tape 33 is formed from a laminated film 50, and has, from the outer surface 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), polybutylene terephthalate (PBT), or the like. The thickness of the base layer 51 is, for example, 5 to 1000 μm.

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

[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 substrate layer 51 and adhesive layer 53 are formed by dry lamination or extrusion lamination on the metal foil barrier layer 52 or on a film provided with the vapor-deposited barrier layer 52.

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

[0058] By disposing the outer tape 33 so as to cover the opposing end surfaces S of the tubular portion 32 and then heat-pressing the outer tape 33, the outer tape 33 is adhered to the tubular portion 32 by the adhesive layer 53. This prevents the end surfaces S of the laminated film 40 from being exposed.

[0059] The adhesive layer 53 can be made of thermally adhesive resins 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), and polybutylene terephthalate (PBT).

[0060] Among these, by using a resin 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, or acid-modified polyethylene, the penetration of water vapor into the packaging container 30 through the adhesive layer 53 can be suppressed, thereby maintaining the characteristics of the electricity 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 for the adhesive layer 53.

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

[0062] The base layer 61 is formed of 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), polybutylene terephthalate (PBT), etc. 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 material layer 61 (the surface opposite to the surface of the inner tape 34 that adheres to the inner surface of the tubular portion 32), thereby making it possible to seal the gap between the inner tape 34 and the closing portion 36 (see FIG. 7).

[0064] The barrier layer 62 is formed of an oxide vapor deposition film (silica, alumina, etc.), a metal vapor deposition film (aluminum, etc.), or a metal foil (aluminum, aluminum alloy, stainless steel, titanium, etc.). The barrier layer 62 can further prevent water vapor from penetrating into the packaging container 30 through the gap between the end faces S. The thickness of the vapor deposition film 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 substrate layer 61 and adhesive layer 63 are formed by dry lamination or extrusion lamination on the metal foil barrier layer 62 or on a film provided with the vapor-deposited barrier layer 62.

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

[0067] The inner surface tape 34 is arranged to cover the opposing end surfaces S of the cylindrical portion 32 and is then heated and pressed, whereby the inner surface tape 34 is adhered to the cylindrical portion 32 by the adhesive layer 63. The adhesive layer 63 may be made of an adhesive such as a urethane-based, epoxy-based, acrylic-based, or polyester-based adhesive.

[0068] If the barrier layer 62 is formed of a metal foil or a metal vapor-deposited film and is exposed on the side edge surface of the inner tape 34, there is a risk of short-circuiting the electricity storage member 20. For this reason, as shown in Fig. 9, the inner tape 34 is etched or the like to form the barrier layer 62 so that its circumferential width is narrower than that of the base material layer 61 and the adhesive layer 63. As a result, the side edge surface of the barrier layer 62 is covered with the base material layer 61 and the adhesive layer 63, and no metal is exposed on the edge surface of the inner tape 34, thereby preventing short-circuiting of the electricity storage member 20.

[0069] If the outer tape 33 can sufficiently block water vapor, the barrier layer 62 may be omitted and the inner tape 34 having the adhesive layer 63 may be used. Furthermore, if the outer tape 33 can block water vapor at a higher level, the inner tape 34 may be omitted.

[0070] According to this embodiment, as in the first embodiment, the body 31 of the packaging container 30 is formed of the laminated film 40, which makes it possible to reduce the weight of the electricity storage device 10. In addition, since acid-modified polypropylene is disposed on the innermost surface of the laminated film 40, the water vapor barrier properties of the electricity storage device 10 are improved, and the life of the electricity storage device 10 can be extended.

[0071] Furthermore, the packaging container 30 is formed by adhering an outer tape 33 to the outer surface of the tubular portion 32, with the end surface S of the laminated film 40 abutting against it. This reduces the exposed area of ​​the heat-adhesive resin layer 43 of the laminated film 40 that forms the tubular portion 32, and the gap between the end surfaces S of the laminated film 40 is covered with the outer tape 33. This makes it possible to further suppress the intrusion of water vapor into the electricity storage device 10 and the volatilization of the electrolyte solution in the electricity storage member 20.

[0072] Furthermore, since the inner surface tape 34 having the resin adhesive layer 63 on its outer surface side is adhered to the inner surface of the tubular portion 32, the gap between the end faces S of the tubular portion 32 is sealed by the inner surface tape 34. This makes it possible to further suppress the intrusion of water vapor into the electricity storage device 10 and the volatilization of the electrolyte solution in the electricity storage member 20.

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

[0074] <Third embodiment> Next, Fig. 10 shows a front cross-sectional view of an electricity storage device 10 according to a third embodiment. For ease of explanation, the same parts as those in the first embodiment shown in Figs. 1 to 6 are denoted by the same reference numerals. This embodiment differs from the first embodiment in the configuration of the connection portion 35. The other parts are the same as those in the first embodiment.

[0075] The body 31 is connected to one end and the other end of the laminated film 40 (see FIG. 9) by a connecting portion 35. The connecting portion 35 bonds the opposing thermal 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 31 and is provided on a short side of the rectangular cross section of the body 31.

[0076] According to this embodiment, as in the first embodiment, the body 31 of the packaging container 30 is formed of the laminated film 40, which makes it possible to reduce the weight of the electricity storage device 10. In addition, since acid-modified polypropylene is disposed on the innermost surface of the laminated film 40, the water vapor barrier properties of the electricity storage device 10 are improved, and the life of the electricity storage device 10 can be extended.

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

[0078] The electricity storage device 10 of the first and second embodiments is more preferable than this embodiment in which the connecting portion 35 is seamed, because the barrier properties of the packaging container 30 are higher and the life of the electricity storage device 10 is extended.

[0079] In the first to third embodiments, the electricity storage member 20 may be a bipolar type in which a plurality of electricity storage elements 21 are stacked and connected in series, and metal tabs provided on both end faces in the stacking direction are connected to the electrodes 37, 38. Furthermore, although the electricity storage member 20 that supplies power to the drive motor 3 is made up of a secondary battery, it may also be a capacitor (such as an electrolytic capacitor, an electric double layer capacitor, or a lithium ion capacitor). [Industrial Applicability]

[0080] The present invention can be widely used in electricity storage devices and electric vehicles equipped with electricity storage devices. [Explanation of symbols]

[0081] 1 Electric vehicle 2 wheels 3 Drive motor 10. Energy storage devices 20 Energy storage materials 21 Energy storage element 27, 28 Lead terminal 30 Packaging containers 31 Torso 32 Cylindrical part 33 Outer tape 34 Inner tape 35 Connection 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 Turned part 47 Step 47 47a Machined surface 53, 63 Adhesive layer S end face

Claims

1. 1. An electricity storage device in which an electricity storage member is sealed in a packaging container, the packaging container having a body portion formed into a cylindrical shape with both axial ends open by connecting one end and the other end of a laminated film with a connecting part, and a metal closing part that closes both axial ends of the body portion, the laminated film being formed by laminating, in order from the outer surface side, a base material layer, a barrier layer, and a thermally adhesive resin layer, the thermally adhesive resin layer having an acid-modified polypropylene on its innermost surface, and the body portion being thermally bonded to the outer surface of the closing part by the thermally adhesive resin layer.

2. 2. The electricity storage device according to claim 1, wherein the body portion has a cross section perpendicular to the axial direction that is rectangular, and the connection portion is disposed on a short side of the cross section.

3. The energy storage device according to claim 1, characterized in that the body portion has a line parallel to the axial direction provided on the laminated film, and is folded along the line to form a rectangular cross section perpendicular to the axial direction.

4. The energy storage device according to claim 1, characterized in that one end of the laminated film has a folded portion that is folded back so as to overlap the processed surface that has been removed in the thickness direction on the outer surface side, and the connection portion is thermally bonded by overlapping the thermal adhesive resin layer at the other end of the laminated film on the thermal adhesive resin layer on the outer surface side of the folded portion.

5. The electricity storage device according to claim 4, wherein the processed surface is formed by removing the laminated film on an outer surface side of the barrier layer.

6. 2. The energy storage device according to claim 1, wherein the connecting portion comprises a cylindrical portion arranged with the end faces of the laminated film butted against each other, and an outer surface tape adhered to the outer surface of the cylindrical portion and covering the end faces.

7. The electricity storage device according to claim 6 , wherein the connecting portion has an inner surface tape that is adhered to the inner surface of the cylindrical portion and covers the end surface.

8. The electricity storage device according to claim 7 , wherein the surface of the inner surface tape opposite to the surface that is bonded to the inner surface of the cylindrical portion is formed of acid-modified polypropylene.

9. 2. The electricity storage device according to claim 1, wherein the connection portion is formed by joining one end and the other end of the laminated film together.

10. An electric vehicle comprising the electricity storage device according to any one of claims 1 to 9.

11. 1. A packaging material for an electricity storage device, comprising a laminated film having one end connected to the other end by a connecting part and formed into a tubular shape with both axial ends open, characterized in that the laminated film is formed by laminating, in order from the outer surface side, a base material layer, a barrier layer, and a thermal adhesive resin layer, and the thermal adhesive resin layer has an acid-modified polypropylene on the innermost surface side.

12. The packaging material for an electricity storage device according to claim 11, wherein a cross section perpendicular to the axial direction is formed into a rectangle, and the connection portion is disposed on a short side of the cross section.

13. The packaging material for a storage battery device according to claim 11, characterized in that the laminated film has a line parallel to the axial direction, and is folded along the line to form a rectangular cross section perpendicular to the axial direction.

14. A packaging container for an electricity storage device, which comprises a body formed from the packaging material for an electricity storage device according to any one of claims 11 to 13, and metal closing portions that close both ends of the body, and which encapsulates an electricity storage member, characterized in that the body is thermally bonded to an outer surface of the closing portion by the thermal adhesive resin layer.

15. A method for manufacturing a packaging container for an electricity storage device that encloses an electricity storage member, comprising: a step of connecting one end and the other end of the laminated film with a connecting portion to form a cylindrical body portion having both axial ends open; a step of closing both ends of the body portion in the axial direction with metal closing portions; the laminated film is formed by laminating, in order from the outer surface side, a base material layer, a barrier layer, and a thermal adhesive resin layer, the thermal adhesive resin layer having an acid-modified polypropylene on its innermost surface, and the body portion is closed by the thermal adhesive resin layer thermally bonding the body portion to the outer surface of the closing portion.

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