JP6654368B2 - Exterior materials for power storage devices - Google Patents

Description

  The present invention relates to a laminate exterior material used as a material for an exterior body of a power storage device and a related technique thereof.

  In this specification, the term “aluminum” is used to mean Al and an Al alloy, the term “copper” is used to mean Cu and a Cu alloy, and the term “nickel” is Ni and The term "titanium" is used to include Ti and Ti alloys. In this specification, the term “metal” is used to include a single metal and an alloy.

  Lithium ion secondary batteries and lithium polymer secondary batteries used in hybrid and electric vehicle batteries, home or industrial stationary storage batteries have been downsized and lightened. Instead, a laminate exterior material in which a resin film is bonded to both surfaces of a metal foil with an adhesive is often used (see Patent Document 1).

  The laminate case described in Patent Literature 1 cuts out a resin film layer inside the case to expose a metal foil to form an electrode connection portion, and cuts out a resin film layer outside the case to expose a metal foil. An electrode terminal is formed.

JP 2013-161675 A

  To obtain electrical continuity by exposing the metal foil by cutting out the resin layer of the laminate exterior material, completely remove the resin film that is the insulator, and also remove the adhesive between the metal foil and the resin film. It must be removed. However, since the adhesive is stuck to the metal foil, it takes time to remove the adhesive, and if left behind, the electrical resistance of the device increases.

  An object of the present invention is to provide a packaging material for a power storage device in which electrical conduction can be reliably obtained by removing a resin layer, and a power storage device using the packaging material.

  That is, the present invention has the configurations described in the following [1] to [6].

[1] For a power storage device in which a heat-resistant resin layer is bonded to one surface of a metal foil via a first adhesive layer, and a thermoplastic resin layer is bonded to the other surface via a second adhesive layer. In exterior materials,
An exterior material for an electric storage device, wherein at least one of the first adhesive layer and the second adhesive layer is made of a conductive adhesive.

  [2] The exterior material for an electric storage device according to the above item 1, wherein the conductive adhesive comprises an adhesive composition including a base adhesive and conductive material particles having an average particle size of 2 μm or less.

  [3] The exterior material for an electric storage device according to the above [1] or [2], wherein a part of the resin layer is removed and a conductive part that is electrically connected to a metal foil is provided on a surface of the resin layer side bonded with the conductive adhesive. .

[4] Heat sealing in which two exterior materials in which a heat-resistant resin layer is bonded to one surface of a metal foil and a thermoplastic resin layer is bonded to the other surface are fused with the thermoplastic resin layers facing each other. An exterior body in which a battery element chamber is formed by being surrounded by
A battery element having a positive electrode element, a negative electrode element, and a separator disposed therebetween, which is housed in the battery element chamber of the outer package,
At least one of the two exterior materials constituting the exterior body is made of the exterior material for an electric storage device described in the item 3 above, and at least one of the positive electrode element and the negative electrode element is electrically connected to the conductive portion of the exterior material. An electricity storage device characterized by the following.

  [5] The electricity storage device according to the above item 4, wherein the positive electrode element and the negative electrode element are a positive electrode foil and a negative electrode foil laminated via a separator.

  [6] The power storage device according to the above item 4, wherein the positive electrode element and the negative electrode element are a positive electrode active material layer and a negative electrode active material layer laminated on a metal foil of an exterior material.

  The exterior material for an electricity storage device according to the above [1], wherein the first adhesive layer between the metal foil and the heat-resistant resin layer, and the second adhesive layer between the metal foil and the thermoplastic resin layer. Since at least one of them is a conductive adhesive, a conductive portion that is conductive to the metal foil can be formed by removing the resin layer. Further, since the adhesive layer is conductive, a conductive portion can be formed without removing the adhesive layer. The adhesive layer not removed becomes a protective layer for the metal foil in the conductive portion.

  In the case of the exterior material for an electric storage device according to the above [2], the conductive material particles are fine particles having an average particle diameter of 2 μm or less, so that the conductive material particles can be uniformly dispersed in the base adhesive to form a good conductor.

  In the exterior material for a power storage device according to the above [3], the conductive portion from which the resin layer has been removed can be used as a conductive portion with a battery element or an outlet for electricity outside the device.

  In the electricity storage device according to the above [4], the conductive portion of the exterior material forming the exterior body can be used as a connection portion between the battery element and the positive electrode element or the negative electrode element, or an electrical outlet of the device.

  According to the electricity storage device described in the above [5], the above effect can be exerted in a device including a positive electrode foil and a negative electrode foil in which a positive electrode element and a negative electrode element are laminated with a separator interposed therebetween.

  According to the electricity storage device described in the above [6], the above-described effect can be exerted in a device including a positive electrode active material layer and a negative electrode active material layer in which a positive electrode element and a negative electrode element are laminated on a metal foil of an exterior material. .

It is sectional drawing of one Embodiment of the exterior | packing material for electric storage devices of this invention. It is sectional drawing of other embodiment of the exterior | packing material for electric storage devices of this invention. It is sectional drawing of other embodiment of the exterior | packing material for electric storage devices of this invention. It is sectional drawing of other embodiment of the exterior | packing material for electric storage devices of this invention. FIG. 2 is a cross-sectional view illustrating one embodiment of the power storage device of the present invention. It is sectional drawing which shows other embodiment of the electric storage device of this invention.

  FIGS. 1 to 4 show an external storage material for an electric storage device according to the present invention, and FIGS. 5 and 6 show electric storage devices in which an external body is formed using the external material shown in FIG.

In the following description, the same reference numerals denote the same items, and redundant description will be omitted.
[Exterior materials for power storage devices]
1 has a heat-resistant resin layer 4 laminated on one surface of a metal foil 2 via a first adhesive layer 3 and a second adhesive layer 5 on the other surface. This is a laminated material in which the thermoplastic resin layer 6 is laminated.

  The exterior material 1a is processed into exterior materials 7, 7a and 7b having the conductive portions 8 and 9 of FIG. 2, and is used as a material of the exterior bodies 50 and 70 of the power storage devices 40 and 41 shown in FIGS. used.

  In the power storage devices 40 and 41, the conductive portions 9 on the thermoplastic resin layer 6 side of the exterior materials 7, 7a and 7b are electrically connected to the battery elements 60 and 80, and the conductive portions 8 on the heat resistant resin layer 4 side are electricity outlets. Becomes

In the present invention, at least one of the first adhesive layer 3 and the second adhesive layer 5 is made of a conductive adhesive described later.
[Exterior material having conductive portion and method for producing the same]
The exterior members 7, 7 a, and 7 b shown in FIG. 2 have a configuration in which the first adhesive layer 3 and the second adhesive layer 5 are made of a conductive adhesive, and the heat-resistant resin layer 4 has a surface facing the heat-resistant resin layer 4. A conductive portion 8 from which the first adhesive layer 3 is exposed by removing the portion, and a portion of the thermoplastic resin layer 6 and the second adhesive layer 5 is removed on the surface on the thermoplastic resin layer 6 side to remove the metal. There is a conductive portion 9 where the foil layer 2 is exposed. FIG. 2 illustrates a conductive portion 8 in which the metal foil 2 is covered with the first adhesive layer 3 and a conductive portion 9 in which the second adhesive layer 5 is removed and the metal foil 2 is exposed. Since it is an agent, it can be formed as a conductive portion that is electrically connected to the metal foil 2 regardless of the presence or absence of the adhesive layer on the metal foil 2. In the exterior material of the present invention, a conductive part of the same form may be formed on the heat-resistant resin layer 4 side and a conductive part of a different form may be formed on the thermoplastic resin layer 6 side.

  The method for producing the packaging material 1a in FIG. 1 and the method for producing the packaging materials 7, 7a, and 7b having a conductive portion from the packaging material 1a are as follows.

  A heat-resistant resin layer 4 is attached to one surface of the metal foil 2 using a conductive adhesive as the first adhesive layer 3, and the other surface is heated using a conductive adhesive as the second adhesive layer 5. The plastic resin layer 6 is bonded. The bonding method is not limited, and the bonding material is appropriately bonded by a known method such as a dry lamination method to produce the exterior material 1a in FIG.

  The heat-resistant resin layer 4 where the conductive portion 8 is formed and the thermoplastic resin layer 6 where the conductive portion 9 is formed are removed from the exterior material 1a. The removal method is not limited, and a method of burning off by irradiating a laser can be exemplified. When forming the conductive portions 8 and 9, the heat-resistant resin layer 4 and the thermoplastic resin layer 6 which are insulating materials may be removed, and the first adhesive layer 3 and the second adhesive layer 5 are made of a conductive adhesive. The conductive portions 8 and 9 can be formed regardless of whether or not the conductive portions 8 and 9 are removed. Further, if the first adhesive layer 3 and the second adhesive layer 5 are insulating adhesives, it is necessary to completely remove the adhesive layers, and the removal work is troublesome. Since the conductive portions 8 and 9 can be formed regardless of the degree of removal of the first adhesive layer 3 and the second adhesive layer 5, the conductive portions 8 and 9 can be formed more easily than the exterior material bonded with an insulating adhesive. Can be formed. Moreover, since the conductive portions 8 and 9 can be formed without cutting deep into the adhesive layer, there is no risk of damaging the metal foil 2.

  Further, the first adhesive layer 3 has a stronger adhesive strength to the heat-resistant resin layer 4 which is a resin than the metal foil 2. Similarly, the second adhesive layer 5 has a stronger adhesive force with the thermoplastic seed layer 6 than the metal foil 2. As described above, it is not inconvenient to leave the conductive adhesive, but it takes time and effort to surely remove the heat-resistant resin layer 4 and the thermoplastic resin layer 6 that are strongly bonded to the adhesive layer so as not to be left. .

  As a method of reducing the trouble of removing the resin layer, a method of sandwiching release paper having a weak adhesive force with respect to the adhesive layer and the resin layer between the portions where the conductive portions 8 and 9 are to be formed at the stage of manufacturing the exterior material. There is. Specifically, as in the case of the exterior material 1b shown in FIG. 3, the release paper 10 is attached to a predetermined position on the first adhesive layer 3, and then the heat-resistant resin layer 4 is attached. Similarly, release paper 10 is attached at a predetermined position on second adhesive layer 5, and then thermoplastic resin layer 6 is attached. Then, the heat-resistant resin layer 4 and the thermoplastic resin layer 6 on the portions where the conductive portions 8 and 9 are to be formed are cut off. Since the release paper 10 has a weak adhesive force to both the first adhesive layer 3 and the heat-resistant resin layer 4, the heat-resistant resin layer 4 can be easily removed. Both can be easily removed. Although the first adhesive layer 3 is not removed, the first adhesive layer 3 functions as a protective layer of the metal foil 2 in the conductive portion 8 because it is a conductive adhesive and there is no problem in using it as the conductive portion 8. I do. By using the release paper 10, the thickness of the first adhesive layer 3 can be reliably left without being reduced, so that the conductive portion 8 can be provided with a stable protection function. Further, when the release paper 10 is an insulating material, it is necessary to remove it. However, when the release paper 10 is a conductive sheet such as graphite or metal, it can be left as a surface material of the conductive portion without being removed. The same applies to the conductive portion 9 on the thermoplastic resin layer 6 side.

  Further, the conductive portion can be formed also from the exterior material 1c shown in FIG. In the exterior material 1c, a first adhesive non-applied portion 3a where no adhesive is applied is formed on a part of the first adhesive layer 3, and an adhesive is applied on a part of the second adhesive layer 5. The second adhesive non-applied portion 5a is formed. The first adhesive non-applied portion 3a and the second adhesive non-applied portion 5a are portions where conductive portions 8 and 9 are to be formed. The conductive portions 8 and 9 can be formed by cutting off the heat-resistant resin layer 4 on the first adhesive-uncoated portion 3a and the thermoplastic resin layer 8 on the second adhesive-uncoated portion 5a. In the conductive portions 8 and 9 formed by this method, the metal foil 2 is exposed.

  The first adhesive non-applied portion 3a and the second adhesive non-applied portion 5a are formed in the adhesive application step, but the adhesive section bleeds or a slight shift of the application position occurs in the application step, so that the conductive sections 8, 9 are formed. Even if the adhesive protrudes into the portion where the is to be formed, if the conductive adhesive is used, the conductivity of the conductive portions 8 and 9 will not be reduced. In the case of an insulative adhesive, it is necessary to strictly control the intrusion of the conductive portions 8 and 9 into the formation planned area, and strict process control is required. However, the use of the conductive adhesive eases strict process control conditions. can do.

The method for manufacturing the exterior material of the present invention is not limited to the above-described method. Further, the method is not limited to bonding the heat-resistant resin layer and the thermoplastic resin layer to the metal foil by the same method. For example, one resin layer may be bonded to the adhesive layer by a method of bonding release paper, and the other resin layer may be bonded to the adhesive layer by a method of forming an adhesive layer having an uncoated portion. Further, the exterior material of the present invention requires that at least one of the first adhesive layer and the second adhesive layer is made of a conductive adhesive. Further, both the exterior material before removing the resin layer (see FIGS. 1, 3, and 4) and the exterior material (see FIG. 2) in which the conductive layer is formed by removing the resin layer correspond to the exterior material of the present invention. .
[Construction material of exterior material]
The metal foil 2 of the exterior material functions as a positive electrode or a negative electrode of the power storage device, or as a conductor connected to the positive electrode or the negative electrode.

  When the metal foil 2 is a positive electrode or a conductor for a positive electrode, a preferable material is a soft aluminum foil, and a thickness of 7 to 150 μm is preferable. A soft aluminum foil having a thickness of 30 to 80 μm is particularly preferable in terms of moldability and cost. On the other hand, when the metal foil 2 is a negative electrode or a negative electrode conductor, a preferable material is a soft or hard aluminum foil, a stainless steel foil, a nickel foil, a copper foil, or a titanium foil. The preferred thickness of these foils is 7 to 150 μm, and preferably 15 to 100 μm in terms of impact resistance, bending resistance and cost.

  Further, the metal foil 2 may be a plating foil or a clad foil. For example, as the second metal foil 21, a plated foil obtained by plating nickel on copper or a clad foil of stainless steel and nickel can be used.

Further, it is preferable that a chemical conversion film is formed on the metal foil layer 2. The chemical conversion film is a film formed by performing a chemical conversion treatment on the surface of the metal foil. By performing such a chemical conversion treatment, corrosion of the metal foil surface due to contents (electrolyte or the like) is sufficiently prevented. In addition, the exposed portion serving as a window for taking out electricity can be prevented from discoloring or deteriorating even if an electrolyte adheres during device fabrication, and the influence of corrosion due to moisture in the atmosphere can be reduced. Although the chemical conversion treatment layer itself has little conductivity, the thickness of the coating film is extremely small, so that there is almost no electric current resistance. For example, a chemical conversion treatment is performed on the metal foil by performing the following treatment. That is, on the surface of the metal foil subjected to the degreasing treatment,
1) phosphoric acid,
Chromic acid and
An aqueous solution of a mixture containing at least one compound selected from the group consisting of a metal salt of fluoride and a nonmetal salt of fluoride; 2) phosphoric acid;
An acrylic resin, at least one resin selected from the group consisting of a chitosan derivative resin and a phenolic resin,
An aqueous solution of a mixture containing at least one compound selected from the group consisting of chromic acid and a chromium (III) salt; 3) phosphoric acid;
An acrylic resin, at least one resin selected from the group consisting of a chitosan derivative resin and a phenolic resin,
At least one compound selected from the group consisting of chromic acid and chromium (III) salts,
An aqueous solution of a mixture containing at least one compound selected from the group consisting of a metal salt of fluoride and a non-metal salt of fluoride, and applying an aqueous solution of any of the above 1) to 3) to the surface of the metal foil After working, a chemical conversion treatment is performed by drying.

The conversion coating, chromium coating weight preferably is 0.1mg ^{/ m 2} ~50mg ^/ m 2 as a (per one surface), in particular ^2mg / ^{m 2 ~20mg} / m ² preferred.

  As the heat-resistant resin constituting the heat-resistant resin layer 4, a heat-resistant resin that does not melt at a heat sealing temperature at the time of heat-sealing the exterior material is used. As the heat-resistant resin, it is preferable to use a heat-resistant resin having a melting point higher by 10 ° C. or more than the melting point of the thermoplastic resin constituting the thermoplastic resin layer 6, and having a melting point higher by 20 ° C. or more than the melting point of the thermoplastic resin. It is particularly preferable to use a heat-resistant resin. For example, in addition to a polyester film and a polyamide film, a stretched film such as a polyethylene naphthalate film, a polybutylene naphthalate film, and a polycarbonate film is preferable. The thickness is preferably in the range of 9 to 50 μm.

  The thermoplastic resin layer 6 is preferably an unstretched film made of at least one thermoplastic resin selected from the group consisting of polyethylene, polypropylene, olefin-based copolymers, acid-modified products thereof, and ionomers. Is preferably in the range of 20 to 80 μm.

  The conductive adhesive is made of, for example, an adhesive composition including a base adhesive and a conductive material. In the adhesive composition for the first adhesive layer 3 to which the heat-resistant resin layer 4 is attached, preferred base adhesives are polyester polyurethane-based adhesives and polyether polyurethane-based adhesives, and preferred conductive materials include carbon black and carbon. Carbon powders such as nanotubes (CNT) and graphite; metal powders such as gold, silver, and copper; and resin powders such as polyacetylene and polyarynin. On the other hand, in the adhesive composition for the second adhesive layer 5 to which the thermoplastic resin layer 6 is bonded, preferred base adhesives are two-component curable olefin adhesives, acrylic resin adhesives, and ethylene-vinyl acetate resin adhesives. An adhesive and an epoxy resin adhesive are preferable, and a preferable conductive material is carbon powder such as carbon black, carbon nanotube (CNT), and graphite.

  In the adhesive composition, it is preferable that a conductive material is uniformly dispersed in the base adhesive in order to suppress a rise in electric resistance due to the adhesive layer as much as possible and form a good conductor. For this reason, it is preferable to use fine particles having an average particle diameter of 2 μm or less, particularly fine particles having an average particle diameter of 0.01 to 0.5 μm. The adhesive layer is preferably thin as long as the adhesive strength can be obtained, but if the particle size of the conductive material is large, the adhesive layer becomes excessively thick. Therefore, the particle size in the above range is preferable. The content of the conductive material in the adhesive composition is preferably from 1 to 20% by mass, and is appropriately set according to the conductive material used. On the surface where the conductive portion is not formed, the respective base adhesives are used for bonding the metal foil and the resin layer.

In addition, other components are allowed to be added to the adhesive composition as long as the adhesion and the conductivity are not impaired. The conductive material content is a content in a state where the adhesive is solidified, and does not include volatile components such as a viscosity adjusting solvent.
[Power storage device]
5 and 6 show two types of power storage devices 40 and 41. FIG. The exterior bodies 50 and 70 of the power storage devices 40 and 41 are formed by using the exterior material 7 or the exterior materials 7, 7 a and 7 b in which the conductive portion 9 on the thermoplastic resin layer 6 side is enlarged. The battery element chambers 57 and 71 are formed by facing each other, and the periphery of the battery element chambers 57 and 71 is thermally sealed. These power storage devices 40 and 41 use the conductive portions 8 and 9 of the exterior members 7 and 7a and 7b as connection portions with battery elements and electrical outlets of the devices.

In FIGS. 5 and 6, the exterior members 7, 7a, and 7b do not show the first adhesive layer 3 and the second adhesive layer 5, and the metal foil 2, the heat-resistant resin layer 4, and the thermoplastic resin layer Only 6 is shown.
<First power storage device>
As shown in FIG. 5, an exterior body 50 of the power storage device 40 includes a main body 51 having a concave portion 52 having a rectangular shape in plan view, a flange 53 extending outward from an opening edge of the concave portion 52, and an outer periphery of the flange 53 of the main body 51. It is manufactured by combining a lid plate 55 having the same size as the size. The concave part 52 forms a battery element chamber 57 for housing the battery element 60.

  The body 51 of the exterior body 50 is formed by subjecting a flat sheet exterior material 7 having conductive portions 8 and 9 on both surfaces of the metal foil layer 2 shown in FIG. 52 is formed, and an undeformed portion around the concave portion 52 is trimmed to the outer circumference of the flange 53. On the other hand, the cover plate 55 is obtained by cutting a flat sheet exterior material 7 having conductive portions 8 and 9 on both surfaces of the metal foil layer 2 into required dimensions. A negative electrode conductive portion 54 is provided on the bottom surface of the concave portion 52 of the main body 51, and a positive electrode conductive portion 56 is provided on the cover plate 55. The positive electrode conductive portion 56 and the negative electrode conductive portion 54 are formed by the conductive portions 8 and 9 of the laminate exterior material 7.

  In the battery element 60, a positive electrode foil 61 and a negative electrode foil 62 are laminated via a separator 63, and an end of the positive electrode foil 61 is joined to the conductive part 9 inside the positive electrode conductive part 56 in the battery element chamber 57. The end of the negative electrode foil 62 is connected to the conductive portion 9 inside the negative electrode conductive portion 54. The positive electrode foil 61 and the negative electrode foil 62 correspond to a positive electrode element and a negative electrode element in the present invention.

  The power storage device 40 is configured such that after the positive electrode foil 61 and the negative electrode foil 62 of the battery element 60 are joined to the respective conductive portions 56 and 54, the battery element 60 is housed in the concave portion 52 of the main body 51, covered with the cover plate 55, The exterior body 50 is sealed by heat-sealing the thermoplastic resin layers 6 at the contact portion between the flange 53 of the main body 51 and the cover plate 55 while leaving the injection port, and heat-sealing the electrolyte inlet after injecting the electrolyte. is there.

In the power storage device 40, the conductive portion 8 outside the positive electrode conductive portion 56 and the conductive portion 8 outside the negative electrode conductive portion 54 serve as outlets for electricity.
<Second power storage device>
As shown in FIG. 6, the power storage device 41 is a thin device in which the exterior body 70 is formed of two flat exterior materials 7a and 7b, and the metal foil 2 of the exterior materials 7a and 7b is used as an electrode. is there. The exterior members 7a and 7b have the same configuration as the exterior member 7 of FIG. 2 except that the conductive portion 9 on the thermoplastic resin layer 6 side has a larger area than the conductive portion 8 on the heat resistant resin layer 4 side.

  The power storage device 41 has a structure in which the positive electrode active material layer 81 is laminated on the conductive portion 9 of one of the package members 7a, and the negative electrode active material layer 82 is laminated on the conductive portion 9 of the other package member 7b. 7b are stacked with a separator 63 interposed therebetween, and the periphery of the conductive portion 9 is thermally sealed together with the electrolyte.

  In the power storage device 41, the metal foil 2 of the exterior material 7 a having the positive electrode active material layer 81 is a positive electrode, the conductive part 8 is an electricity outlet, and the metal foil 2 of the exterior material 7 b having the negative electrode active material layer 82 is a negative electrode. And the conductive part 8 is an electric outlet. The positive electrode active material layer 81 and the negative electrode active material layer 82 correspond to the positive electrode element and the negative electrode element in the present invention, and the positive electrode active material layer 81, the negative electrode active material layer 82, and the separator 63 are the electrode element 80. The space where the electrode element 80 exists is the battery element chamber 71.

  Further, in the power storage device 41, the pole active material layer can be formed in the step of attaching the exterior material. For example, a positive electrode or negative electrode active material layer is applied to a desired position of the metal foil 2 and dried, and the second adhesive layer 5 is formed in a state where the surface of the positive active material layer is covered with a masking sheet. The plastic resin layer 6 is bonded. Thereafter, the thermoplastic resin layer 6 and the second adhesive layer 5 are removed together with the masking sheet. Also in this method, the use of the conductive adhesive has an effect of suppressing an increase in resistance value due to bleeding of the adhesive, and the effect of the conductive adhesive can be enjoyed.

  In the present invention, the conductive portion (outlet for electricity) on the outer surface of the exterior body of the power storage device is not limited to being formed at a symmetrical position of the conductive portion on the thermoplastic resin layer side with the metal foil interposed therebetween, and the heat-resistant resin layer It is not limited to forming on the side of the surface. For example, if one of the exterior members is extended outside the heat sealing portion to expose the thermoplastic resin layer, the conductive portion on the outer surface of the exterior body can be formed on the surface on the thermoplastic resin layer side. Both the conductive part to the battery element and the conductive part to the outside of the device may be formed on the surface on the thermoplastic resin layer side, and such an exterior material is also included in the technical scope of the present invention. Therefore, the exterior material of the power storage device has a conductive part at least on the thermoplastic resin layer side, and the presence or absence of the conductive part on the heat resistant resin layer side differs depending on the form of the exterior body. Further, a packaging material in which at least one of the first adhesive layer and the second adhesive layer is made of a conductive adhesive is included in the technical scope of the present invention. This is because, if a method with less influence of the adhesive is used for bonding one resin layer, a corresponding effect can be obtained if a conductive adhesive is used only for bonding the other resin layer. The bonding method with little influence of the adhesive is a method of forming and bonding an adhesive layer having an adhesive non-applied portion, which is referred to, for example, as the exterior material 1c in FIG.

  Further, the power storage device is included in the technical scope of the present invention as long as at least one of the two outer materials constituting the outer body is made of the outer material of the present invention. For example, the cover 55 of the exterior body 50 of the power storage device 40 in FIG. 5 is changed to an exterior material having no conductive portions 8 and 9, and a tab lead is connected to the positive electrode foil 61 of the battery element 60 so as to be drawn out of the exterior body. Modifications are also included in the present invention.

As a test material of each example, a three-layer material in which a metal foil and a thermoplastic resin layer were bonded with different adhesives was prepared. The metal foil and the thermoplastic resin layer were common to each example. The metal foil used was a soft aluminum foil (JIS H4160 A8079H) having a thickness of 40 μm, and the thermoplastic resin layer used was an unstretched polypropylene film having a thickness of 40 μm.
(Example 1)
A conductive adhesive composition was prepared by adding graphite fine powder having an average particle size of 2 μm as a conductive material to a two-part curable acid-modified polypropylene-based adhesive as a base adhesive and uniformly dispersing the same. The conductive material content in the adhesive composition is 20% by mass.

The adhesive composition was applied to one surface of a metal foil and dried at 100 ° C. A release paper coated with a 20 mm × 20 mm silicone-based release agent is attached to the surface of the dried adhesive layer, a thermoplastic resin layer is laminated and pressed, and cured for 3 days in an aging furnace at 40 ° C. for testing. Materials were produced. The thickness of the adhesive layer after curing was 2 μm.
(Example 2)
A test material was prepared in the same manner as in Example 1 except that the conductive material of the adhesive composition was changed to acetylene black having an average particle size of 0.03 μm, and the content was changed to 1% by mass.
(Example 3)
A test material was prepared in the same manner as in Example 1 except that the conductive material of the adhesive composition was changed to graphite fine powder having an average particle size of 1 μm, and the content was changed to 7% by mass.
(Example 4)
A test material was prepared in the same manner as in Example 1, except that the conductive material of the adhesive composition was changed to carbon black having an average particle size of 0.1 μm, and the content was changed to 3% by mass.
(Comparative example)
A test material was produced in the same manner as in Example 1, except that only the base adhesive was used as the adhesive.
(Reference example)
As the adhesive, only the base adhesive was used. The adhesive was applied while forming an adhesive-uncoated portion of 20 mm × 20 mm on one surface of the metal foil, and the thermoplastic resin layer was bonded. The drying conditions of the applied adhesive and the curing conditions after bonding the thermoplastic resin layer are the same as in Example 1.

  For the test materials of Examples 1 to 4 and Comparative Example, the thermoplastic resin layer was cut by irradiating a laser to a corresponding portion of the periphery of the graphite sheet in the thermoplastic resin layer, and the thermoplastic resin layer was removed together with the release paper. Then, the adhesive layer was exposed to form a conductive portion of 20 mm × 20 mm.

  In addition, for the test material of the reference example, the thermoplastic resin layer is cut and removed by irradiating a laser to a corresponding portion of the periphery of the adhesive uncoated portion in the thermoplastic resin layer, and the metal foil is exposed. A conductive part of 20 mm × 20 mm was formed.

  For each test material on which the conductive portion was formed, the electrical resistance between the conductive portion formed by removing the thermoplastic resin layer and the other surface of the metal foil was measured. That is, in Examples 1 to 4 and Comparative Example, the resistance value of the laminated portion of the metal foil and the adhesive layer was measured, and in Reference Example, the resistance value of the metal foil alone was measured. Table 1 shows the measurement results.

  As shown in Table 1, the test materials of Examples 1 to 4 were prepared by laminating a thermoplastic resin layer with a conductive adhesive, without removing the adhesive layer. It can be seen that the increase in the resistance value is slight. Also, the test material of the comparative example shows that the resistance value increases even with an adhesive layer having a thickness of 2 μm, and it cannot be a conductive part.

  In the above embodiment, the conductive part is formed on the surface of the exterior material for a power storage device on the thermoplastic resin layer side, but the same result can be obtained with the conductive part formed on the surface of the heat resistant resin layer side.

  Although the reference example is an example using an adhesive containing no conductive material, when combined with the results of Examples 1 to 4, the use of the conductive adhesive makes it possible to use an adhesive-uncoated portion when transferring the adhesive. It can be considered that the increase in the resistance value is very small even if the position shift or the bleeding of the adhesive occurs.

  INDUSTRIAL APPLICABILITY The present invention can be suitably used as an outer package material of a power storage device that is reduced in size and weight.

1a, 1b, 1c, 7, 7a, 7b: exterior material for power storage device 2: metal foil 3: first adhesive layer 3a, 5a: adhesive-uncoated portion 4: heat-resistant resin layer 5: second adhesive 6 ... thermoplastic resin layers 8, 9 ... conductive part 10 ... release paper 40, 41 ... electricity storage devices 50, 70 ... exterior bodies 57, 71 ... battery element chambers 60, 80 ... battery elements 61 ... positive electrode foil (positive element)
62 ... negative electrode (negative electrode element)
63: separator 81: positive electrode active material layer (positive electrode element)
82 ... Negative electrode active material layer (negative electrode element)

Claims (5)

A heat-resistant resin layer is bonded to one surface of a metal foil via a first adhesive layer, and a thermoplastic resin layer is bonded to the other surface via a second adhesive layer. ,
Ri Do from at least one electrically conductive adhesive of the first adhesive layer and second adhesive layer,
An exterior material for a power storage device, comprising: a conductive portion that is partially removed from a resin layer and is electrically connected to a metal foil on a surface on a resin layer side bonded with the conductive adhesive.   The exterior material for an electric storage device according to claim 1, wherein the conductive adhesive comprises an adhesive composition including a base adhesive and conductive material particles having an average particle size of 2 µm or less. Two exterior materials in which a heat-resistant resin layer is bonded to one surface of the metal foil and a thermoplastic resin layer is bonded to the other surface are surrounded by a heat-sealed portion where the thermoplastic resin layers face each other and are fused together. An exterior body in which the battery element chamber is formed by
A battery element having a positive electrode element, a negative electrode element, and a separator disposed therebetween, which is housed in the battery element chamber of the outer package,
At least one of the two exterior materials constituting the exterior body is made of the exterior material for a power storage device according to claim 1 or 2 , and at least one of a positive electrode element and a negative electrode element is provided on a conductive portion of the exterior material. An electricity storage device characterized by being conductive. The power storage device according to claim 3 , wherein the positive electrode element and the negative electrode element are a positive electrode foil and a negative electrode foil laminated with a separator interposed therebetween. The power storage device according to claim 3 , wherein the positive electrode element and the negative electrode element are a positive electrode active material layer and a negative electrode active material layer laminated on a metal foil of an exterior material.

Images