Power storage device, power storage device case, and power storage device exterior material

Abstract

This power storage device case (1) is provided with a case body (3) which has a top wall (31), a side wall (32) provided on the outer peripheral edge of the top wall (31), and a flange (33) provided on the outer periphery of the side wall (32), and in which a housing part (35) is provided inside the top wall (31) and the side wall (32). The case body (3) is formed from a molded body of a power storage device exterior material (1). The exterior material (1) includes: a resin base layer (11); a metal foil layer (12) that is laminated on an inner surface side of the base layer (11); a resin heat-resistant gas barrier layer (13) that is laminated on an inner surface side of the metal foil layer (12); and a resin sealant layer (15) that is laminated on an inner surface side of the heat-resistant gas barrier layer (13). The sealant layer (15) is provided with an opening (2) for exposing the heat-resistant gas barrier layer (13) in the housing part (35), and an outer peripheral edge section (21) of the opening (2) is set at the flange (33).

Description

Electricity storage device, case for electricity storage device, and exterior material for electricity storage device

[0001] The present invention relates to an electricity storage device such as an all-solid-state battery used as a high-power battery such as an in-vehicle battery, a battery for portable devices such as a mobile electronic device, or a battery for storing regenerative energy, and further to a case for the electricity storage device and an exterior material for the electricity storage device used in the electricity storage device.

[0002] Conventionally widely used lithium ion secondary batteries use a liquid electrolyte, which can lead to the destruction of the separator due to leakage of the electrolyte or the formation of dendrites, and in some cases, can cause a short circuit, resulting in fire or other problems.

[0003] In contrast, all-solid-state batteries use a solid electrolyte, so they do not leak or develop dendrites, and the separator is not damaged. Therefore, there is no risk of fire caused by separator damage, and they are attracting much attention from the perspective of safety.

[0004] A typical all-solid-state battery is configured by sealing an all-solid-state battery body, such as an electrode active material and a solid electrolyte, inside an exterior material serving as a casing. As research into solid electrolytes advances in all-solid-state batteries, it has gradually become apparent that the performance required of the exterior material differs from that of exterior materials for batteries using conventional liquid electrolytes, and various exterior materials have been proposed to satisfy the performance requirements for all-solid-state batteries.

[0005] The exterior material for an all-solid-state battery has a basic structure including a metal foil layer and a heat-sealing layer (sealant layer) laminated on the inside of the metal foil layer, and the all-solid-state battery main body is encapsulated by heat-sealing the sealant layer.

[0006] For example, the all-solid-state battery packaging material disclosed in Patent Document 1 below has a protective film interposed between a metal foil layer and a sealant layer, and uses a sealant layer with high hydrogen sulfide gas permeability. Furthermore, the all-solid-state battery packaging material disclosed in Patent Document 2 uses a sealant layer with low hydrogen sulfide gas permeability. Furthermore, the all-solid-state battery packaging material disclosed in Patent Document 3 uses a gas-absorbing sealant layer. Furthermore, the all-solid-state battery packaging material disclosed in Patent Document 4 is configured by laminating a vapor-deposited film layer on the inner surface of a sealant layer.

[0007] Patent No. 6777276 Patent No. 6747636 JP 2020-187855 JP 2020-187835

[0008] However, the above-mentioned conventional all-solid-state batteries have a problem in that gases such as hydrogen sulfide gas generated by a reaction between the solid electrolyte and water may leak out.

[0009] On the other hand, all-solid-state batteries have a higher resistance and generate more heat than liquid electrolytes because electron (ion) exchange occurs in the solid electrolyte during charging and discharging. However, it is believed that the performance of all-solid-state batteries is not affected even in high-temperature environments, and currently, no consideration has been given to high-temperature countermeasures (cooling performance) including in the above-mentioned Patent Documents 1 to 4. However, as battery technology advances toward higher output and higher capacity, it is fully expected that improved cooling performance will also be required in all-solid-state batteries in the future.

[0010] The above describes the issues with all-solid-state batteries, but similar issues may arise in other power storage devices.

[0011] The present invention has been made in view of the above-mentioned problems, and has an object to provide an electricity storage device, a case for an electricity storage device, and an exterior material for an electricity storage device that can ensure sufficient cooling performance while preventing leakage of gases such as hydrogen sulfide gas. Other objects of the present invention will become apparent from the embodiments (including first and second modifications) described below.

[0012] In order to solve the above problems, the present invention comprises the following means.

[0013] [1] A case for an electricity storage device, comprising a case body having a top wall, side walls provided on the outer periphery of the top wall, and a flange provided on the outer periphery of the side wall, and having a storage section provided inside the top wall and the side wall, wherein the case body is constituted by a molded body of an exterior material for an electricity storage device, and the exterior material for an electricity storage device comprises a resin base layer, a metal foil layer laminated on the inner surface side of the base layer, a resin heat-resistant gas barrier layer laminated on the inner surface side of the metal foil layer, and a resin sealant layer laminated on the inner surface side of the heat-resistant gas barrier layer, wherein an opening is provided in the sealant layer to expose the heat-resistant gas barrier layer inside the storage section, and the outer periphery of the opening is set to the flange.

[0014] [2] An electricity storage device comprising: a case body used in the electricity storage device case described in the preceding paragraph 1; an electricity storage device body accommodated in an accommodating section of the case body; and a closing member heat-sealed to a flange of the case body in a state where the closing member closes a lower open portion of the accommodating section in the case body.

[0015] [3] The electric storage device according to the preceding paragraph 2, wherein the blocking member comprises a resin base layer, a metal foil layer laminated on the inner surface of the base layer, a resin heat-resistant gas barrier layer laminated on the inner surface of the metal foil layer, and a resin sealant layer laminated on the inner surface of the heat-resistant gas barrier layer, and an opening is provided in the sealant layer of the blocking member to expose the heat-resistant gas barrier layer of the blocking member to the storage section.

[0016] [4] An exterior packaging material for an electricity storage device used in the electricity storage device case described in the preceding paragraph 1, the exterior packaging material having a sheet-like shape, and comprising an intended opening portion that is to become the opening, and an intended flange portion that is to become the flange, wherein an outer peripheral edge portion of the intended opening portion is set in the intended flange portion.

[0017] [5] The packaging material for an electricity storage device according to the preceding item 4, wherein the arithmetic mean height Sa as the surface roughness of the heat-resistant gas barrier layer is set to 0.04 μm to 1.5 μm.

[0018] [6] The packaging material for an electricity storage device according to item 4 or 5, wherein the resin constituting the sealant layer has an MFR set to 2 to 20 g / 10 min at 230° C. and a load of 2.16 kgf.

[0019] According to the electricity storage device case of invention [1], a heat-resistant gas barrier layer is provided between the metal foil layer and the sealant layer, and an opening is formed in the sealant layer. Therefore, when the electricity storage device is fabricated by enclosing the electricity storage device body, the opening without the sealant layer allows heat generated from the electricity storage device body to be efficiently transferred and dissipated to the metal foil layer through the opening and the heat-resistant gas barrier layer without being blocked by the sealant layer, thereby ensuring sufficient heat dissipation and cooling performance. Furthermore, in this invention, because the heat-resistant gas barrier layer is disposed on the inner surface of the metal foil layer, even if the solid electrolyte of the electricity storage device body reacts with moisture in the outside air to generate gases such as hydrogen sulfide, the heat-resistant gas barrier layer can reliably prevent the gas from leaking. Furthermore, because the opening is formed over a wide area from the top surface to the side surface of the electricity storage device body, heat dissipation and cooling performance can be further improved.

[0020] According to the electricity storage device of the invention [2], it is possible to ensure a good aesthetic appearance, and further, as described above, it is possible to reliably prevent leakage of gases such as hydrogen sulfide gas while ensuring sufficient heat dissipation and cooling properties.

[0021] According to the electricity storage device of the invention [3], openings are also formed in the sealant layer of the closing member, so that heat dissipation and cooling properties can be further improved.

[0022] According to the packaging material for an electricity storage device of invention [4], when an electricity storage device is manufactured, a good appearance can be ensured, and further, as described above, sufficient heat dissipation and cooling properties can be ensured while reliably preventing leakage of gases such as hydrogen sulfide gas.

[0023] According to the packaging material for an electricity storage device of the invention [5], the slipperiness of the heat-resistant gas barrier layer against a forming punch is improved, and formability can be further improved.

[0024] According to the packaging material for an electricity storage device of the invention [6], the resin reservoir portion can be formed in a better shape, and the peel strength can be further improved.

[0025] FIG. 1 is a schematic cross-sectional view showing an all-solid-state battery as an electricity storage device according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view showing an enlarged view of a main portion of FIG. 1 . FIG. 3 is an exploded perspective view showing a schematic all-solid-state battery according to an embodiment. FIG. 4 is a bottom view (interior view) showing a schematic case body of an all-solid-state battery according to an embodiment. FIG. 5 is a schematic cross-sectional view showing an exterior material for a case body of an all-solid-state battery according to an embodiment. FIG. 6 is a schematic cross-sectional view for explaining a method of forming an opening in an exterior material according to an embodiment. FIG. 7 is a schematic cross-sectional view showing a mold device for molding a case body using an exterior material according to an embodiment. FIG. 8 is a schematic cross-sectional view for explaining an example of a heat-sealing method according to an embodiment, where FIG. 8( a) is a schematic cross-sectional view showing a state immediately before heat-sealing, and FIG. 8( b) is a schematic cross-sectional view showing a state immediately after heat-sealing. FIG. 9 is a schematic cross-sectional view for explaining another example of a heat-sealing method according to an embodiment, where FIG. 9( a) is a schematic cross-sectional view showing a state immediately before heat-sealing, and FIG. 9( b) is a schematic cross-sectional view showing a state immediately after heat-sealing. FIG. 10 is a schematic cross-sectional view showing an all-solid-state battery according to a first modified example of the present invention. FIG. 11 is a schematic cross-sectional view showing an all-solid-state battery according to a second modification of the present invention.

[0026] Fig. 1 is a schematic cross-sectional view showing an all-solid-state battery as an electricity storage device according to an embodiment of the present invention, Fig. 2 is a schematic cross-sectional view showing an enlarged view of a main portion of Fig. 1, and Fig. 3 is an exploded perspective view showing a schematic view of the all-solid-state battery according to the embodiment. As shown in these figures, the all-solid-state battery according to this embodiment includes a case body 3 and a closing member 4 as a casing, and an all-solid-state battery body 5 as an electricity storage device body housed and sealed in the casing.

[0027] 5 is a schematic cross-sectional view showing an exterior material 1 constituting the case body 3 of an all-solid-state battery according to an embodiment. As shown in the figure, the exterior material 1 includes a base material layer 11 disposed on the outermost side, a metal foil layer 12 laminated and bonded to the inner surface of the base material layer 11 via an adhesive layer (not shown), a heat-resistant gas barrier layer 13 laminated and bonded to the inner surface of the metal foil layer 12 via an adhesive layer (not shown), and a sealant layer 15 laminated and bonded to the inner surface of the heat-resistant gas barrier layer 13 via an adhesive layer 14. In the present invention, when describing the positions of the layers constituting the exterior material 1 in terms of directions, the direction toward the base material layer 11 (upper side in FIG. 3 ) is referred to as the outside, and the direction toward the sealant layer 15 (lower side in FIG. 3 ) is referred to as the inside.

[0028] The exterior material 1 constituting the blocking member 4 also has the same structure as the exterior material 1 constituting the case body 3 described above.

[0029] FIG. 4 is a schematic diagram of the case body 3 as viewed from the bottom side (inner side). As shown in FIGS. 1 to 4 , the case body 3 is formed from a molded body of the exterior material 1 and integrally includes a top wall 31, a side wall (peripheral side wall) 32 extending downward from the outer peripheral edge of the top wall 31, and a flange 33 provided on the outer periphery of the lower end of the side wall 32. A storage section 35 is formed inside the top wall 31 and the side wall 32. The closing member 4 is formed from the sheet-like exterior material 1. An all-solid-state battery body 5 is accommodated in the storage section 35 of the case body 3, and the closing member 4 is arranged to close the lower open end of the storage section 35. The closing member 4 is arranged with its sealant layer 15 facing inward (upward), and the sealant layer 15 of the flange 33 of the case body 3 and the sealant layer 15 of the outer peripheral edge of the closing member 4 are overlapped and face each other. The overlapping sealant layers 15 are joined together by thermal bonding (heat sealing) to form an all-solid-state battery in which the all-solid-state battery body 5 is housed in a sealed state within the casing (the case body 3 and the closing member 4).

[0030] Furthermore, in the case body 3 of the all-solid-state battery, the sealant layer 15 and the adhesive layer 14 are removed in a portion corresponding to the accommodation portion 35, thereby forming an opening 2. Furthermore, in the closing member 4, the sealant layer 15 and the adhesive layer 14 are removed in a portion corresponding to the accommodation portion 35, thereby forming an opening 2. Through the opening 2 in the case body 3 and the closing member 4, the heat-resistant gas barrier layer 13 of the exterior material 1 is exposed inside the accommodation portion 35 and is disposed so as to face the all-solid-state battery body 5.

[0031] Furthermore, in the all-solid-state battery of this embodiment, a tab lead (not shown) is provided for taking out electricity. One end (inner end) of this tab lead is adhesively fixed to the all-solid-state battery body 5, and the middle part is arranged so as to pass through the heat-sealed part between the flange 33 of the case body 3 and the outer peripheral edge part of the closing member 4, and the other end side is drawn out to the outside.

[0032] Each part of the all-solid-state battery of this embodiment will be described in detail below.

[0033] The base material layer 11 of the packaging material 1 is made of a heat-resistant resin film having a thickness of 5 μm to 50 μm. Suitable resins that can be used to make up this base material layer 11 include oriented polyamide film, oriented polyester (PET, PBT, PEN, etc.), and oriented polyolefin (PE, PP, etc.).

[0034] The metal foil layer 12 has a thickness set to 5 μm to 120 μm and has the function of blocking the penetration of oxygen and moisture from the surface (outer surface) side. Aluminum foil, SUS foil (stainless steel foil), copper foil, nickel foil, etc. can be suitably used as this metal foil layer 12. In this embodiment, the terms "aluminum," "copper," and "nickel" are used to mean alloys thereof.

[0035] Furthermore, if the metal foil layer 12 is subjected to a plating process or the like, the risk of pinholes occurring is reduced, and the function of blocking the penetration of oxygen and moisture can be further improved.

[0036] Furthermore, if the metal foil layer 12 is subjected to a chemical conversion treatment such as chromate treatment, the corrosion resistance is further improved, so that defects such as chipping can be more reliably prevented, and the adhesion to the resin can be improved, thereby further improving durability.

[0037] The sealant layer (thermal adhesive resin layer) 15 has a thickness of 20 μm to 100 μm and is made of a thermal adhesive (thermal adhesive) resin film. Suitable resins for the sealant layer 15 include polyethylene (LLDPE, LDPE, HDPE), polyolefins such as polypropylene, olefin copolymers, acid-modified products thereof, and ionomers, such as non-oriented polypropylene (CPP, IPP).

[0038] Considering that electricity is extracted using a tab lead, that is, in consideration of sealing properties and adhesiveness with the tab lead, it is preferable to use a polypropylene-based resin (non-oriented polypropylene film (CPP, IPP)) as the sealant layer 15.

[0039] The heat-resistant gas barrier layer 13 is made of a heat-resistant and insulating resin film. Preferred resins for the heat-resistant gas barrier layer 13 include polyamide (such as 6-nylon, 66-nylon, and MXD nylon), polyester (such as polyethylene terephthalate (PET)), polybutylene terephthalate (PBT), and polyethylene naphthalate (PEN)), cellophane, polyvinylidene chloride (PVDC), and oriented polypropylene (OPP).

[0040] In this embodiment, the resin constituting the heat-resistant gas barrier layer 13 is a resin having a predetermined resistance to hydrogen sulfide (H ２ The range of this hydrogen sulfide gas permeability is not limited. Specifically, the heat-resistant gas barrier layer 13 preferably has a hydrogen sulfide gas permeability of 15 cc·mm / (m ２ It is preferable that the resin be 10 {cc·mm / (m ２It is preferable that the resin used is 4.0 {cc·mm / (m ２ It is preferable that the heat-resistant gas barrier layer 13 be made of a resin having a tensile strength of 0.1-0.25 MPa or less. In other words, when the hydrogen sulfide gas permeability of the heat-resistant gas barrier layer 13 is set to the above-mentioned specific value or less, when hydrogen sulfide gas is generated as a result of a reaction between the solid electrolyte material and moisture in the outside air, the heat-resistant gas barrier layer 13 can reliably prevent the hydrogen sulfide gas from leaking to the outside. When the hydrogen sulfide gas permeability of the heat-resistant gas barrier layer 13 is too high, the generated hydrogen sulfide gas tends to pass through the exterior material 1 (heat-resistant gas barrier layer 13) and leak to the outside.

[0041] For reference, the "D" included in the unit of hydrogen sulfide gas permeability corresponds to "Day (24 h)."

[0042] In this embodiment, the thickness (original thickness) of the heat-resistant gas barrier layer 13 is not particularly limited, but is preferably set to 3 μm to 50 μm, more preferably 10 μm to 40 μm. That is, when the thickness of the heat-resistant gas barrier layer 13 is set within this range, the hydrogen sulfide gas and water vapor gas permeation suppression effect can be reliably obtained, and even if the sealant layer 15 melts and flows out due to thermal adhesion, the heat-resistant gas barrier layer 13 can reliably ensure insulation, and the packaging material 1 can be reliably thinned. If the heat-resistant gas barrier layer 13 is too thin, the gas permeation suppression effect and insulation property tend not to be ensured. If the heat-resistant gas barrier layer 13 is too thick, not only cannot the packaging material 1 be thinned, but the effect of making it thicker than necessary tends to be insufficient.

[0043] In this embodiment, it is preferable to use a resin film as the heat-resistant gas barrier layer 13. That is, the entire film serves as a barrier layer, and therefore, unlike a vapor-deposited film or the like, no barrier cracks occur, and the barrier properties can be improved.

[0044] Furthermore, a non-stretched film or a slightly stretched film can be used as the resin film constituting the heat-resistant gas barrier layer 13, and it is particularly preferable to use a non-stretched film. That is, when a non-stretched film is used, formability and gas barrier properties can be further improved.

[0045] The heat-resistant gas barrier layer 13 of the present embodiment has good insulating properties, and maintains good insulating properties even after the all-solid-state battery body 5 is enclosed (sealed) with the case body 3 and the closing member 4 as the exterior material 1 of the present embodiment.

[0046] In this embodiment, the arithmetic mean height Sa of the heat-resistant gas barrier layer 13 as a surface roughness is not limited. It is particularly preferable to use a heat-resistant gas barrier layer 13 having an Sa of 0.04 μm to 1.5 μm. That is, an Sa of 0.04 μm or more is particularly preferable because it reliably improves the slipperiness with respect to the forming punch 7 and reliably improves the formability. Furthermore, an Sa of 1.5 μm or less is particularly preferable because it reliably prevents the occurrence of adhesion defects in the adhesive layer 14. If Sa is too small, the contact area with the forming punch 7 increases, which increases frictional resistance and tends to result in a decrease in formability. If Sa is too large, it tends to result in adhesion defects in the adhesive layer 14 and a decrease in adhesion.

[0047] In this embodiment, the adhesive constituting the adhesive layer 14 that bonds between the heat-resistant gas barrier layer 13 and the sealant layer 15 can be a two-component curing type, an energy ray (UV, X-ray, etc.) curing type, or the like, and among these, urethane-based adhesives, olefin-based adhesives, acrylic-based adhesives, epoxy-based adhesives, etc. can be preferably used. Furthermore, the thickness of the adhesive layer 14 is set to 2 μm to 5 μm.

[0048] In this embodiment, the adhesive used to bond between the base material layer 11 and the metal foil layer 12, and between the metal foil layer 12 and the heat-resistant gas barrier layer 13 can be the same as the adhesive used for the adhesive layer 14, and it is preferable to set the thickness to the same.

[0049] In this embodiment, the opening 2 on the case body 3 side has its outer peripheral edge 21 provided on the flange 33 of the case body 3. Furthermore, the opening 2 on the closing member 4 side is formed to correspond to the lower surface of the all-solid-state battery body 5 (see FIG. 1 ).

[0050] In the present embodiment, the opening 2 formed in the case body 3 and the closing member 4 does not have the adhesive layer 14 for bonding the sealant layer 15 to the heat-resistant gas barrier layer 13, and the heat-resistant gas barrier layer 13 is exposed (exposed) to the inside through the opening 2, and in a state where the all-solid-state battery is fabricated, the heat-resistant gas barrier layer 13 is disposed so as to face the upper surface, peripheral side surface, and lower surface of the all-solid-state battery body 5.

[0051] In this embodiment, the adhesive layer 14 is not provided on the opening 2, but this is not limiting, and in the present invention, the adhesive layer 14 may be provided on at least a part of the opening 2. However, not providing the adhesive layer 14 as in this embodiment can improve heat dissipation properties.

[0052] Next, a method for manufacturing the exterior material 1 in this embodiment will be described. Needless to say, in the present invention, the method for manufacturing the exterior material 1 is not limited (the same applies to the method for manufacturing the case body 3 and the method for manufacturing the all-solid-state battery, which will be described later).

[0053] In this embodiment, a laminate without a sealant layer is first produced by, for example, dry lamination. That is, a resin film for the base layer 11 is bonded via an adhesive to the outer surface of a metal foil (metal foil layer 12) that has been subjected to a surface treatment and a chemical conversion treatment as necessary, and a resin film for the heat-resistant gas barrier layer 13 is bonded via an adhesive to the inner surface of the metal foil, thereby producing a laminate without a sealant layer in which the metal foil layer 12 and the heat-resistant gas barrier layer 13 are laminated on the inner surface side of the base layer 11.

[0054] It is also possible to produce a laminate without a sealant layer by extrusion lamination, i.e., by extruding the resin composition for the base layer 11 and the resin composition for the heat-resistant gas barrier layer 13 onto the inner and outer surfaces of a metal foil, respectively, and laminating them.

[0055] Next, a resin film for the sealant layer 15 is adhered to the inner surface of the above-mentioned sealant layer-free laminate (the inner surface of the heat-resistant gas barrier layer 13) via an adhesive (adhesive layer 14) to form the sealant layer 15. The sealant layer 15 is adjusted so that it can be reliably peeled off and removed from the portion of the sealant layer 15 where the opening 2 is to be formed (planned opening portion 2a) by the following method.

[0056] 5 , in a first formation method, when the sealant layer 15 is formed on the heat-resistant gas barrier layer 13, an adhesive is applied as the adhesive layer 14 to the inner surface of the resin film as the heat-resistant gas barrier layer 13 using a gravure roll or the like, and the resin film as the sealant layer 15 is attached via the adhesive layer 14. When the adhesive is applied to the heat-resistant gas barrier layer 13 using a gravure roll or the like, an adhesive-uncoated portion 10 where no adhesive is applied is formed in the intended opening portion 2 a. Then, a resin film for the sealant layer is attached to the heat-resistant gas barrier layer 13 having this adhesive-uncoated portion 10, and dried.

[0057] Then, as shown in Figure 6, the opening portion 2a of the sealant layer 15 corresponding to the adhesive-uncoated portion 10 is cut out using a laser cutter, a roll blade, etc. (laser cutting, etc.) to form the opening 2 (first formation method).

[0058] In the second formation method, before applying the adhesive to the heat-resistant gas barrier layer 13, a release paper is temporarily attached to an area of ​​the heat-resistant gas barrier layer 13 corresponding to the intended opening portion 2 a, and in this state, the adhesive is applied to the heat-resistant gas barrier layer 13 with a gravure roll or the like, and a resin film for the sealant layer 15 is attached and dried.

[0059] Thereafter, the opening planned portion 2a of the sealant layer 15 corresponding to the temporarily fastened portion of the release paper is cut out together with the adhesive and release paper using a laser cutter, a roll blade, or the like to form the opening 2. When using this second formation method, only the resin film for the sealant layer may be removed from the portion corresponding to the temporarily fastened portion of the release paper, or the resin film for the sealant layer and the adhesive may be removed, or the resin film for the sealant layer, the adhesive, and the release paper may be removed. In other words, the release agent (such as the release paper) or the adhesive may be left in the opening 2.

[0060] Another possible formation method is to form through-holes as openings 2 in the resin film for the sealant layer 15 before bonding the film to the heat-resistant gas barrier layer 13, and then attach the resin film for the sealant layer with openings to the heat-resistant gas barrier layer 13 via an adhesive (another formation method). However, with this other formation method, it is difficult to apply the adhesive evenly, and it is difficult to attach the resin film for the sealant layer with openings accurately and precisely. Therefore, in this embodiment, it is preferable to adopt the first and second formation methods.

[0061] As shown in Figures 5 and 6, the sheet-like exterior material 1 before molding includes a top wall planned portion 31a which is the portion intended to become the top wall 31, a side wall planned portion 32a which is the portion intended to become the side wall 32, and a flange planned portion 33a which is the portion intended to become the flange 33.

[0062] In this embodiment, the outer peripheral edge 21a of the intended opening portion 2a is set within the range of the intended flange portion 33a.

[0063] The flange portion 33a also includes a heat seal portion for heat sealing, as will be described later.

[0064] Note that the exterior material 1 in Figures 5 and 6 is described as an example of forming an exterior material 1 with an opening for the case body 3, but the same applies when forming an exterior material 1 with an opening for the blocking member 4.

[0065] 7 is a schematic cross-sectional view showing a mold device for molding the case body 3 using the exterior material 1. As shown in the figure, this mold device includes a die 6 as an upper mold, and a punch 7 and a blank holder 70 as a lower mold.

[0066] The die 6 has a molding recess 65 formed on the lower surface thereof for molding the housing portion 35 (top wall 31 and side wall 32 ) of the case body 3 .

[0067] The punch 7 is disposed in correspondence with the forming recess 65 of the die 6 , and the blank holder die 70 is disposed on the outer periphery of the punch 7 and faces the outer periphery of the lower surface of the die 6 .

[0068] Then, a sheet-like opening-equipped exterior material 1 serving as a molding material is placed so that its sidewall-provisional portion 32a corresponds to the outer peripheral edge of the tip of the punch 7. In this state, the flange-provisional portion 33a of the exterior material 1 is sandwiched and supported by the outer periphery of the die 6 and the blank holder die 70, and the punch 7 is driven into the molding recess 65 of the die 6, thereby pressing the exterior material 1. This produces a case body molded body (molding material) having a housing portion 35 (top wall 31 and side wall 32) and a flange 33 outside the housing portion 35. The flange 33 of this molded body is then cut to a predetermined size, thereby producing the case body 3 of this embodiment. In this case body 3, openings 2 are arranged throughout the entire area of ​​the housing portion 35, and the outer peripheral edge 21 of the openings 2 is positioned on the flange 33, as shown in FIGS. 1 to 4 .

[0069] 8(a) is a schematic cross-sectional view for explaining a heat-sealing method when producing an all-solid-state battery in this embodiment by heat-sealing the case body 3 and the closing member 4. As shown in the figure, the heat-sealing method of this embodiment uses a pair of sealing dies 8 for heat-sealing the flange 33 of the case body 3 and the outer periphery of the closing member 4, which is a sheet-like exterior material 1 in which the opening 2 is formed and which has been cut to a predetermined size.

[0070] On the other hand, the all-solid-state battery body 5 is accommodated in the accommodation portion 35 of the case body 3 to be heat-sealed, and the closing member 4 is arranged so as to close the accommodation portion 35 from below, and the sealant layer 15 of the flange 33 of the case body 3 and the sealant layer 15 of the outer peripheral edge portion of the closing member 4 are arranged so as to face and overlap each other. In this state, the flange 33 of the case body 3 and the outer peripheral edge portion of the closing member 4 are sandwiched between a pair of sealing dies 8 and heated. As a result, the overlapping sealant layers 15 are heat-sealed and joined together, thereby producing an all-solid-state battery in which the all-solid-state battery body 5 is accommodated in an airtight state within the case body 3 and the closing member 4.

[0071] 8(b) is an enlarged schematic cross-sectional view of the periphery of the heat-sealed portion in an all-solid-state battery heat-sealed by the method of FIG. 8(a). As shown in the figure, after the heat-sealing process, a resin reservoir S2 is formed by the resin that melts and flows out from the heat-sealed portion S1 into the housing portion 35. This resin reservoir S2 is disposed along the heat-resistant gas barrier layer 13 on the inner surface of the side wall 32 of the case body 3, and the resin reservoir S2 is in close contact with the heat-resistant gas barrier layer 13 of the case body 3 without any gaps.

[0072] In this embodiment, in the state before heat sealing shown in Figure 8 (a), it is preferable that the outer peripheral edge 21 of the opening 2 is positioned closer to the storage section 35 than the storage section side end position P1 of the heat seal portion S1 between the flange 33 of the case body 3 and the blocking member 4. In particular, as shown in Figures 4 and 8(a), of the distances (lengths) La, Lb from the storage section side end position P1 of the heat-sealed portion S1 at the outer peripheral edge 21 of the opening 2, the length La along the width direction of the opening 2 (the vertical direction in Figure 4) is preferably set to 0.05% to 150% of the width direction dimension Wa of the opening 2 (the distance between the opposing outer peripheral edges 21), more preferably set to 0.1% to 140%, even more preferably set to 0.15% to 130%, even more preferably set to 0.15% to 120%, even more preferably set to 0.2% to 110%, even more preferably set to 0.2% to 100%, even more preferably set to 0.3% to 80%, even more preferably set to 0.3% to 50%.

[0073] The same applies to the length Lb along the length direction (left-right direction in FIG. 4 ) of the opening 2, among the lengths La and Lb. That is, the length Lb is preferably set to 0.05% to 150% of the length direction dimension Wb of the opening 2 (the distance between the opposing outer peripheral edges 21), more preferably 0.1% to 140%, even more preferably 0.15% to 130%, even more preferably 0.15% to 120%, even more preferably 0.2% to 110%, even more preferably 0.2% to 100%, even more preferably 0.3% to 80%, and even more preferably 0.3% to 50%.

[0074] 9( a), when the distances La and Lb are set to be short (the distances La and Lb are 0%), after the heat sealing process, a resin reservoir S2 made of the melted resin that flows out from the heat-sealed portion S1 into the housing portion 35 is formed so as to be in close contact with the sealant layer 15 on the closing member 4 side, and as shown in FIG. 9( b), a gap S3 tends to be formed between the resin reservoir S2 and the heat-resistant gas barrier layer 13 on the case body 3 side. If a gap S3 is formed between the heat-resistant gas barrier layer 13 of the case body 3 and the resin reservoir S2 (sealant layer 15) in this way, peel stress between the case body 3 and the closing member 4 tends to concentrate in the gap S3, and this peel stress tends to cause interlayer delamination in the adhesive layer between the resin reservoir S2 (sealant layer 15) and the heat-resistant gas barrier layer 13, resulting in a decrease in peel strength (sealing strength).

[0075] In contrast, as shown in Fig. 8(a), when the distances La and Lb are set within the above-mentioned preferred ranges, the resin reservoir S2 is reliably adhered to the heat-resistant gas barrier layer 13 on the inner surface of the side wall 32 of the case body 3, and no gap is formed between the resin reservoir S2 and the heat-resistant gas barrier layer 13, as shown in Fig. 8(b). Therefore, the peel stress does not concentrate between the sealant layer 15 and the heat-resistant gas barrier layer 13, but acts on the thermally bonded portion between the sealant layers 15 between the case body 3 and the closing member 4. This makes it possible to reliably prevent inadvertent delamination due to the peel stress, and ensure sufficient peel strength (sealing strength).

[0076] In this embodiment, the heat-sealed portion S1 refers to the portion where the sealant layer 15 between the case body 3 and the closure member 4 is heat-sealed or adhered in the area clamped by a pair of sealing molds 8 at the flange 33 of the case body 3 and the outer peripheral edge of the closure member 4.

[0077] In this embodiment, the MFR (melt flow rate) of the resin constituting the sealant layer 15 is not limited. It is particularly preferable to set (adjust) the MFR of this resin to 2 to 20 g / 10 min (230°C, load 2.16 kgf). That is, when the MFR is within this range, the melting property during heat sealing is very good, favorable resin reservoir S2 as shown in FIG. 8(b) is easily formed, and the seal strength can be reliably improved. If the MFR is too low, the resin flow during heat sealing is poor, making it difficult for resin reservoirs to form, and the sealability tends to be reduced. If the MFR is too high, the resin flow during heat sealing is too great, making it difficult to form resin reservoir S2, and the sealability tends to be reduced.

[0078] The size and shape of the opening 2 provided in the closing member 4 may be larger or smaller than those of the bottom surface of the all-solid-state battery main body 5. To improve heat dissipation, it is preferable to form the opening 2 of the closing member 4 large, but it is more preferable to make it equal to or smaller than the dimensions of the outer peripheral edge portion 21 (sealant layer) of the opening 2 of the case main body 3.

[0079] According to the all-solid-state battery of the present embodiment having the above-described configuration, the heat-resistant gas barrier layer 13 is provided between the metal foil layer 12 and the sealant layer 15 in the case body 3 and the closing member 4, and the opening 2 is formed in the top wall 31 and the side wall 32 by removing a part of the sealant layer 15. Therefore, heat generated from the all-solid-state battery body 5 is efficiently transferred to the metal foil layer 12 via the opening 2 and the heat-resistant gas barrier layer 13 and dissipated without being blocked by the sealant layer 15, thereby ensuring sufficient heat dissipation and cooling properties.

[0080] In particular, in the present embodiment, the outer peripheral edge 21 of the opening 2 in the case body 3 is set to the flange 33 of the case body 3, so that a large opening 2 can be formed that corresponds to almost the entire area of ​​the all-solid-state battery body 5, and heat dissipation and cooling properties can be further improved.

[0081] Furthermore, according to the all-solid-state battery of this embodiment, since the heat-resistant gas barrier layer 13 is disposed on the inner surface side of the metal foil layer 12, even if the solid electrolyte of the all-solid-state battery body 5 reacts with moisture in the outside air to generate hydrogen sulfide gas or the like, leakage of the gas can be reliably prevented by the heat-resistant gas barrier layer 13. Furthermore, the gas permeation prevention action of the heat-resistant gas barrier layer 13 can prevent the intrusion of moisture such as water vapor gas from the outside, and therefore the generation of hydrogen sulfide gas itself due to the reaction between the moisture and the solid electrolyte can also be suppressed, making it possible to more reliably prevent leakage of hydrogen sulfide gas or the like.

[0082] In this embodiment, the resin constituting the heat-resistant gas barrier layer 13 is selected from those having a water vapor gas permeability of 50 (g / m) as measured in accordance with JIS K7129-1 (humidity sensor method: 40°C, 90% Rh). ２ / day) or less. That is, when this configuration is adopted, the heat-resistant gas barrier layer 13 can more reliably prevent moisture penetration and more reliably prevent the generation and leakage of hydrogen sulfide gas.

[0083] In this embodiment, it is preferable to use a resin having a thermal conductivity of 0.2 W / (m·K) or more as the resin constituting the heat-resistant gas barrier layer 13. That is, when this configuration is used, the heat conductivity of the heat-resistant gas barrier layer 13 can be sufficiently ensured, and the cooling performance of the all-solid-state battery body 5 can be further improved.

[0084] Furthermore, in the all-solid-state battery of this embodiment, in the portion where the opening 2 is formed, although the sealant layer 15 is not present between the all-solid-state battery body 5 and the metal foil layer 12, the heat-resistant gas barrier layer 13 having insulating properties is disposed therebetween, and therefore, the heat-resistant gas barrier layer 13 can reliably ensure insulation.

[0085] Furthermore, when the exterior packaging material 1 is cut with a laser cutter, a roll blade, or the like (laser punching, etc.) to form the opening 2, a damaged area caused by the laser punching or the like may be formed in the outer peripheral edge 21 of the opening, which may result in defects such as cracks or pinholes. However, in this embodiment, the outer peripheral edge 21 of the opening is formed in the flange 33 of the case body 3, so that the adverse effects of the damaged area can be avoided. That is, the flange 33 of the case body 3 is heat-sealed, and a resin reservoir S2 formed by the heat sealing is formed in the damaged area (the outer peripheral edge 21 of the opening). Therefore, the damaged area can be covered and repaired by the resin reservoir S2, so that the adverse effects of the damaged area caused by the laser punching can be reliably avoided.

[0086] In this embodiment, it is preferable to use a resin that constitutes the heat-resistant gas barrier layer 13 that has a melting point that is at least 10° C. higher than that of the resin that constitutes the sealant layer 15. In other words, if the heat-resistant gas barrier layer 13 has a high melting point, even if the sealant layer 15 melts when the packaging material 1 is thermally bonded, the heat-resistant gas barrier layer 13 can be prevented from melting and flowing out, and therefore the gas permeation suppression effect and insulating properties of the heat-resistant gas barrier layer 13 can be obtained more reliably.

[0087] Furthermore, in the all-solid-state battery of this embodiment, the sealant layer 15 is not formed in the portion of the exterior packaging material 1 that corresponds to the all-solid-state battery body 5, and therefore, the space for accommodating the all-solid-state battery body 5 can be made larger (thicker) accordingly. Therefore, in the all-solid-state battery of this embodiment, compared to conventional all-solid-state batteries, a larger-sized all-solid-state battery body 5 can be accommodated without changing the external dimensions of the case body 3, and therefore, high output and high capacity can be achieved while achieving a thinner design.

[0088] In the all-solid-state battery of the above embodiment, the case where the opening 2 is formed in both the case body 3 and the closing member 4 has been described as an example, but the present invention is not limited to this. As shown in FIG. 10 , the opening 2 may be formed in the case body 3, and the opening 2 may not be formed in the closing member 4.

[0089] In addition, the all-solid-state battery of this embodiment shown in FIG. 1 is arranged so that the case body 3 is disposed on the upper side and the blocking member 4 is disposed on the lower side, but this is not limited thereto. In the present invention, the all-solid-state battery shown in FIG. 1 may be inverted, that is, the case body 3 which is a molded body is disposed on the lower side and the sheet-like blocking member 4 is disposed on the upper side.

[0090] Furthermore, in the present invention, a molded body may be used as the blocking member 4. For example, as shown in Fig. 11 , a tray-shaped molded body having a shape obtained by inverting the case body 3 upside down may be used as the blocking member 4, and the casing of the all-solid-state battery may be formed by the case body 3 which is a molded body and the tray-shaped blocking member 4 which is also a molded body. In this case, by using a similar configuration for the blocking member 4 as the case body 3, the same effect can be obtained with the blocking member 4.

[0091] In the above embodiment, a case has been described in which an all-solid-state battery is used as the electricity storage device of the present invention, but the present invention is not limited to this, and can also be applied to electricity storage devices other than all-solid-state batteries.

[0092] The exterior packaging material for an electricity storage device of the present invention can be suitably used as a material for a battery case (casing) for accommodating an all-solid-state battery main body such as an all-solid-state battery.

[0093] This application claims priority from Japanese Patent Application No. 2024-24784, filed on February 21, 2024, the disclosure of which is incorporated herein by reference in its entirety.

[0094] It should be understood that the terms and expressions used herein are used for the purpose of explanation and not for limiting interpretation, and do not exclude any equivalents of the features shown and described herein, but also allow various modifications within the claimed scope of the present invention.

[0095] DESCRIPTION OF SYMBOLS 1: Exterior material 11: Base material layer 12: Metal foil layer 13: Heat-resistant gas barrier layer 15: Sealant layer 2: Opening 21: Outer peripheral edge portion 2a: Pre-opening portion 21a: Outer peripheral edge portion 3: Case body 32: Side wall 33: Flange 33a: Pre-flange portion 35: Storage portion 4: Closing member 5: All-solid-state battery body (electricity storage device body) S1: Heat-sealed portion

Claims

1. A case for an electricity storage device comprising a case body having a top wall, side walls provided on the outer periphery of the top wall, and flanges provided on the outer periphery of the side walls, and having a storage section provided inside the top wall and the side walls, wherein the case body is formed from a molded product of an exterior packaging material for an electricity storage device, and the exterior packaging material for an electricity storage device comprises a resin base layer, a metal foil layer laminated on the inner surface of the base layer, a resin heat-resistant gas barrier layer laminated on the inner surface of the metal foil layer, and a resin sealant layer laminated on the inner surface of the heat-resistant gas barrier layer, and an opening is provided in the sealant layer to expose the heat-resistant gas barrier layer inside the storage section, and the outer periphery of the opening is set to the flange.

2. An electricity storage device comprising: a case body used in the electricity storage device case according to claim 1; an electricity storage device body accommodated in a housing section of the case body; and a closing member heat-sealed to a flange of the case body while closing the lower open end of the housing section in the case body.

3. The electricity storage device according to claim 2, wherein the blocking member comprises a resin base layer, a metal foil layer laminated on the inner surface of the base layer, a resin heat-resistant gas barrier layer laminated on the inner surface of the metal foil layer, and a resin sealant layer laminated on the inner surface of the heat-resistant gas barrier layer, and an opening is provided in the sealant layer of the blocking member to expose the heat-resistant gas barrier layer of the blocking member to the storage section.

4. An exterior packaging material for an electricity storage device used in the electricity storage device case described in claim 1, characterized in that it has a sheet-like shape and comprises an intended opening portion that is to become the opening and an intended flange portion that is to become the flange, and the outer peripheral edge portion of the intended opening portion is set in the intended flange portion.

5. The packaging material for an electricity storage device according to claim 4, wherein the arithmetic mean height Sa of the surface roughness of the heat-resistant gas barrier layer is set to 0.04 μm to 1.5 μm.

6. The packaging material for an electricity storage device according to claim 4 or 5, wherein the resin constituting the sealant layer has an MFR set to 2 to 20 g / 10 min at 230° C. and a load of 2.16 kgf.

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