Outer materials for all-solid-state batteries and all-solid-state batteries

Abstract

The present invention provides an outer package material for all-solid-state batteries, the outer package material being free from gas leakage, while exhibiting sufficient insulation properties.　The present invention relates to an outer package material for all-solid-state batteries, the outer package material being used for the purpose of having a solid-state battery main body 5 sealed therein, while being provided with a base material layer 11, a metal foil layer 12 that is superposed on the inner surface of the base material layer 11, and a sealant layer 13 that is superposed on the inner surface of the metal foil layer 12. A heat-resistant gas barrier layer 21 is arranged between the metal foil layer 12 and the sealant layer 13; and the heat-resistant gas barrier layer 21 is configured from a resin that has a hydrogen sulfide gas permeability of 15 cc∙mm / (m2∙D∙MPa) or less as determined in accordance with JIS K7126-1.

Description

[Technical Field]

[0001] This invention relates to an outer casing material for all-solid-state batteries used as high-power batteries such as automotive batteries, batteries for portable devices such as mobile electronic devices, and batteries for storing regenerative energy, as well as to all-solid-state batteries themselves. [Background technology]

[0002] Conventional lithium-ion secondary batteries, which are widely used, use a liquid electrolyte, and therefore, leakage or dents can destroy the separator, potentially leading to short circuits and fires.

[0003] In contrast, all-solid-state batteries use a solid electrolyte, so they do not leak or form dendrites, and the separator is not damaged. Therefore, there is no concern about ignition due to separator damage, and they are attracting considerable attention from a safety perspective.

[0004] Conventional all-solid-state batteries consist of a casing containing the battery body, including electrode active materials and a solid electrolyte. As research into solid electrolytes progresses, the performance requirements for the casing have gradually become different from those of conventional liquid electrolyte batteries, and various casing materials have been proposed to meet the performance requirements for all-solid-state batteries.

[0005] The outer casing for all-solid-state batteries has a basic structure that includes a metal foil layer and a heat-sealable layer (sealant layer) laminated inside it. The solid-state battery body is enclosed by heat-sealing the sealant layer.

[0006] For example, the casing material for all-solid-state batteries shown in Patent Document 1 has a protective film interposed between the metal foil layer and the sealant layer, and the sealant layer uses a material with high hydrogen sulfide gas permeability. Furthermore, the casing material for all-solid-state batteries shown in Patent Document 2 uses a material with high hydrogen sulfide gas permeability as the sealant layer. Furthermore, the casing material for all-solid-state batteries shown in Patent Document 3 uses a material that absorbs gas as the sealant layer. Furthermore, the casing material for all-solid-state batteries shown in Patent Document 4 is constructed by laminating a vapor-deposited film layer on the inner surface of the sealant layer. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Patent No. 6777276 [Patent Document 2] Patent No. 6747636 [Patent Document 3] Japanese Patent Publication No. 2020-187855 [Patent Document 4] Japanese Patent Publication No. 2020-187835 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] However, all-solid-state batteries using the exterior materials shown in Patent Documents 1 and 2 have a problem in that when the solid electrolyte reacts with moisture in the air to generate hydrogen sulfide gas, there is a risk of that hydrogen sulfide gas leaking out.

[0009] Furthermore, in the exterior materials shown in Patent Documents 2 to 4, when the sealant layer is melt-bonded (heat-bonded) to enclose the battery body, there is a problem that the resin constituting the sealant layer may melt and leak out, causing the sealant layer to become partially thinner, which may reduce the protective function of the sealant layer against the metal foil layer and lead to a decrease in insulation performance.

[0010] Preferred embodiments of the present invention have been made in view of the aforementioned and / or other problems in the related art. Preferred embodiments of the present invention can significantly improve upon existing methods and / or apparatus.

[0011] This invention has been made in view of the above-mentioned problems, and aims to provide an exterior material for an all-solid-state battery and an all-solid-state battery that can ensure sufficient insulation even when the sealant layer is heat-bonded, and furthermore, can prevent leakage of hydrogen sulfide gas and the like that generated inside when the battery body is sealed.

[0012] Other objectives and advantages of the present invention will become apparent from the following preferred embodiments. [Means for solving the problem]

[0013] To solve the above problems, the present invention comprises the following means.

[0014] [1] An outer casing material for an all-solid-state battery for enclosing a solid-state battery body, comprising a base layer, a metal foil layer laminated on the inner surface side of the base layer, and a sealant layer laminated on the inner surface side of the metal foil layer, A heat-resistant gas barrier layer is provided between the metal foil layer and the sealant layer. The aforementioned heat-resistant gas barrier layer has a hydrogen sulfide gas permeability of 15 {cc·mm / (m³)} measured in accordance with JIS K7126-1. 2 An outer casing material for all-solid-state batteries, characterized by being composed of resin with a pressure of 0.5 MPa or less.

[0015] [2] The resin constituting the heat-resistant gas barrier layer has an original thickness of "da0" and a thickness of "da1" when pressed under the conditions of 200°C, 0.2 MPa, and 5 sec. 1 ≥ da1 / da0 ≥ 0.9 An outer casing material for an all-solid-state battery as described in item 1 above, configured to satisfy the relationship.

[0016] [3] The heat-resistant gas barrier layer has a thickness set to 3 μm to 50 μm, and the exterior material for all-solid-state batteries according to item 1 or 2 above.

[0017] [4] The sealant layer is composed of a resin with a hydrogen sulfide gas permeability of 100 {cc·mm / (m 2 ·D·MPa)} or less, and the exterior material for all-solid-state batteries according to any one of items 1 to 3 above.

[0018] [5] For the resin constituting the sealant layer, when the original thickness is “db0” and the thickness when pressed under the conditions of 200 °C, 0.2 MPa, and 5 seconds is “db1”, 0.5 ≥ db1 / db0 ≥ 0.1 and is configured to satisfy the relational expression, and the exterior material for all-solid-state batteries according to any one of items 1 to 4 above.

[0019] [6] The resin constituting the heat-resistant gas barrier layer has a water vapor gas permeability measured in accordance with JIS K7129-1 (humidity sensor method, 40 °C, 90% Rh) of 50 (g / m 2 / day) or less, and the exterior material for all-solid-state batteries according to any one of items 1 to 5 above.

[0020] [7] An all-solid-state battery, characterized in that an all-solid-state battery body is encapsulated in the exterior material for all-solid-state batteries according to any one of items 1 to 6 above.

Advantages of the Invention

[0021] According to the exterior material for all-solid-state batteries of Invention [1], since a heat-resistant gas barrier layer is interposed between the metal foil layer and the sealant layer, it is possible to reliably prevent the generated hydrogen sulfide gas from leaking to the outside. Further, when sealing the all-solid-state battery body with this exterior material, even if the resin of the sealant layer melts and flows out when the sealant layer is thermally bonded, resulting in a decrease in the insulation performance of the sealant layer, the heat-resistant gas barrier layer remains, and thus the insulation performance can be reliably ensured by the heat-resistant barrier layer.

[0022] According to the all-solid-state battery enclosure material of Invention [2][3], when the solid-state battery body is sealed by heat bonding, a sufficient thickness of the heat-resistant gas barrier layer can be ensured, thereby reliably preventing hydrogen sulfide gas leakage and reliably ensuring good insulation.

[0023] According to the all-solid-state battery casing material of the invention [4], the release of hydrogen sulfide gas can also be prevented by the sealant layer, thus more reliably preventing the leakage of hydrogen sulfide gas.

[0024] According to the all-solid-state battery enclosure material of the invention [5], when the solid-state battery body is sealed by heat bonding, a certain thickness of the sealant layer can be secured, thereby further improving insulation and sealing performance.

[0025] The exterior material for all-solid-state batteries of the invention [6] can prevent the ingress of moisture and suppress the generation of hydrogen sulfide gas itself, thereby more reliably preventing the leakage of hydrogen sulfide gas.

[0026] According to the invention [7], since it specifies an all-solid-state battery using the exterior materials of the above inventions [1] to [6], the same effects as above can be obtained. [Brief explanation of the drawing]

[0027] [Figure 1] Figure 1 is a schematic cross-sectional view showing an all-solid-state battery, which is an embodiment of this invention. [Figure 2] Figure 2 is a schematic cross-sectional view showing the exterior material used in the all-solid-state battery of the embodiment. [Figure 3] Figure 3 is a schematic plan view showing a sample used for insulation evaluation. [Figure 4] Figure 4 is a schematic cross-sectional view of the insulation evaluation sample shown in Figure 3, and corresponds to the cross-sectional view along line IV-IV in Figure 3. [Modes for carrying out the invention]

[0028] Figure 1 is a schematic cross-sectional view showing an all-solid-state battery according to an embodiment of this invention, and Figure 2 is a schematic cross-sectional view showing the exterior material 1 used in the all-solid-state battery. As shown in both figures, the exterior material 1, which constitutes the casing of the all-solid-state battery according to this embodiment, is made of a laminate such as a laminate sheet.

[0029] This exterior material 1 comprises a base material layer 11 positioned on the outermost side, a metal foil layer 12 laminated on the inner side of the base material layer 11, a heat-resistant gas barrier layer 21 laminated on the inner side of the metal foil layer 12, and a sealant layer 13 laminated on the inner side of the heat-resistant gas barrier layer 21. In this embodiment, each layer 11-13, 21 of the exterior material 1 is bonded to each other via an adhesive (adhesive layer) applied by the dry lamination method. In other words, the exterior material 1 of this embodiment is composed of a laminate consisting of a base material layer 11 / adhesive layer / metal foil layer 12 / adhesive layer / heat-resistant gas barrier layer 21 / adhesive layer / sealant layer 13.

[0030] In this embodiment, as shown in Figure 1, a solid-state battery is manufactured by enclosing the solid-state battery body 5 with the exterior material 1 having the above configuration. Specifically, two rectangular exterior materials 1,1 are stacked vertically via the solid-state battery body 5, and the sealant layers 13,13 on the outer edges of the two (pair) exterior materials 1,1 are bonded together in an airtight (sealed) state by heat bonding (heat sealing), thereby manufacturing a solid-state battery in which the solid-state battery body 5 is housed within a bag-shaped casing made of the exterior materials 1,1.

[0031] In this embodiment of the all-solid-state battery, although not shown in the illustration, a tab lead is provided for drawing electricity. One end (inner end) of this tab lead is bonded and fixed to the solid-state battery body 5, the middle part passes between the outer edges of the two outer casings 1,1, and the other end (outer end) is led out to the outside.

[0032] In this embodiment, the casing is formed by bonding two flat exterior materials 1,1 together. However, the invention is not limited to this, and in this invention, at least one of the two exterior materials may be pre-formed into a tray shape, and the tray-shaped exterior material may be bonded to the other tray-shaped or flat exterior material to form the casing.

[0033] The detailed configuration of the outer casing material 1 of the all-solid-state battery in this embodiment will be described below.

[0034] The base layer 11 of the exterior material 1 is composed of a heat-resistant resin film with a thickness of 5 μm to 50 μm. Suitable resins for this base layer 11 include polyamide, polyester (PET, PBT, PEN), polyolefin (PE, PP), etc.

[0035] The metal foil layer 12 has a thickness of 5 μm to 120 μm and has the function of blocking the intrusion of oxygen and moisture from the surface (outside). Suitable materials for this metal foil layer 12 include aluminum foil, SUS foil (stainless steel foil), copper foil, nickel foil, etc. In this embodiment, the terms "aluminum," "copper," and "nickel" are used to include their alloys as well.

[0036] Furthermore, applying a plating treatment to the metal foil layer 12 reduces the risk of pinhole formation and further improves the function of blocking the intrusion of oxygen and moisture.

[0037] Furthermore, if the metal foil layer 12 is subjected to a chemical conversion treatment such as chromate treatment, its corrosion resistance is further improved, making it possible to more reliably prevent defects such as chipping, and also improving adhesion with the resin, thereby further enhancing durability.

[0038] The sealant layer 13 has a thickness of 10 μm to 100 μm and is composed of a heat-adhesive (heat-fusible) resin film. Suitable resins for this sealant layer 13 include polyethylene (LLDPE, LDPE, HDPE), polyolefins such as polypropylene, olefin copolymers, acid-modified products thereof, and ionomers, such as unoriented polypropylene (CPP, IPP).

[0039] As for the sealant layer 13, considering the extraction of electricity using tab leads, that is, considering the sealing and adhesion properties with respect to the tab leads, it is preferable to use a polypropylene resin (unoriented polypropylene film (CPP, IPP)).

[0040] The heat-resistant gas barrier layer 21 is composed of a resin film having heat resistance and insulating properties. Preferably, the resin used to constitute this heat-resistant gas barrier layer 21 is polyamide (6-nylon, 66-nylon, MXD nylon, etc.), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), cellophane, polyvinylidene chloride (PVDC), etc.

[0041] In this embodiment, the resin constituting the heat-resistant gas barrier layer 21 must have a predetermined hydrogen sulfide (H2S) gas permeability. Specifically, the heat-resistant gas barrier layer 21 has a hydrogen sulfide gas permeability of 15 {cc·mm / (m³) in measurements conforming to JIS K7126-1. 2 It must be composed of resin with a minimum pressure of 10 cc / mm / (m²) or less. 2 It is preferable to use a resin with a minimum output of 4.0 {cc·mm / (m²)}. 2·D·MPa)} It is preferably composed of the following resin. That is, when the hydrogen sulfide gas permeability of the heat-resistant gas barrier layer 21 is set to be not more than the above specific value, when hydrogen sulfide gas is generated due to the reaction of the solid electrolyte material with moisture in the outside air, the heat-resistant gas barrier layer 21 can prevent the hydrogen sulfide gas from leaking to the outside. In other words, if the hydrogen sulfide gas permeability of the heat-resistant gas barrier layer 21 is too high, the generated hydrogen sulfide gas may leak to the outside through the exterior material 1 (heat-resistant gas barrier layer 21), which is not preferable.

[0042] For reference, the "D" included in the unit of hydrogen sulfide gas permeability corresponds to "Day (24h)".

[0043] Here, in the present embodiment, it is preferable that the sealant layer 13 of the exterior material 1 is composed of a resin having a hydrogen sulfide gas permeability of 100 {cc·mm / (m 2 ·D·MPa)} or less in accordance with JIS K7126-1. That is, when the hydrogen sulfide gas permeability of the sealant layer 13 is set to be not more than the above specific value, the hydrogen sulfide gas leakage prevention effect of the sealant layer 13 is combined with the hydrogen sulfide gas permeation suppression effect of the heat-resistant gas barrier layer 21, and it is possible to more reliably prevent the hydrogen sulfide gas from leaking to the outside.

[0044] In addition, in the present embodiment, as the resin constituting the heat-resistant gas barrier layer 21, the water vapor gas permeability measured in accordance with JIS K7129-1 (humidity sensor method, 40°C, 90%Rh) is preferably set to 50 (g / m 2 / day) or less, more preferably 40 (g / m 2 / day) or less, and even more preferably 20 (g / m 2It is preferable to adopt a value of less than or equal to the specified value per day. In other words, hydrogen sulfide gas is generated when external moisture permeates the exterior material 1 and reacts with the solid electrolyte material. However, if the water vapor gas permeability of the heat-resistant gas barrier layer 21 is set to less than or equal to the specified value mentioned above, the intrusion of moisture by the heat-resistant gas barrier layer 21 can be prevented, and furthermore, in combination with the gas barrier function of the metal foil layer 12, the intrusion of moisture can be prevented even more reliably, the generation of hydrogen sulfide gas itself can be reliably prevented, and consequently, the leakage of hydrogen sulfide gas to the outside can be prevented more reliably.

[0045] In this embodiment, the thickness (original thickness) of the heat-resistant gas barrier layer 21 is preferably set to 3 μm to 50 μm, and more preferably to 10 μm to 40 μm. That is, when the thickness of the heat-resistant gas barrier layer 21 is set within this range, the above-mentioned effect of suppressing the permeation of hydrogen sulfide gas and water vapor gas can be reliably obtained, and even if the sealant layer 13 melts and flows out due to thermal bonding, the heat-resistant gas barrier layer 21 can reliably ensure insulation. In other words, if the heat-resistant gas barrier layer 21 is too thin, there is a risk that the gas permeation suppression effect and insulation cannot be ensured, which is undesirable. Conversely, if the heat-resistant gas barrier layer 21 is too thick, not only is it not possible to thin the exterior material 1, but the effect of making it thicker than necessary cannot be fully obtained, which is also undesirable.

[0046] In this embodiment, it is preferable to use a resin film as the heat-resistant gas barrier layer 21. That is, since the entire film acts as a barrier layer, barrier cracks do not occur, unlike vapor-deposited films, and barrier properties can be improved.

[0047] Furthermore, the resin film constituting the heat-resistant gas barrier layer 21 can be an unoriented film or a slightly stretched film, and it is particularly preferable to use an unoriented film. In other words, when an unoriented film is used, the moldability and gas barrier properties can be further improved.

[0048] Furthermore, in this embodiment, it is preferable that the resin (resin film) constituting the heat-resistant gas barrier layer 21 is configured such that, with the original thickness being "da0" and the thickness obtained when pressed under the conditions of 200°C, 0.2 MPa, and 5 seconds being "da1", the remaining percentage "da1 / da0" is 0.9 or more, that is, it satisfies the relationship A "1≧da1 / da0≧0.9". This relationship A corresponds to a configuration in which the reduction rate of the thickness of the heat-resistant gas barrier layer 21 is 10% or less when the exterior material 1 is heat-bonded. In this embodiment, if the above relationship A is satisfied, even if the exterior material 1 is heat-bonded and the solid battery body 5 is sealed, the reduction in the thickness of the heat-resistant gas barrier layer 21 can be suppressed and a sufficient thickness can be secured, so that the gas permeation suppression effect described above can be reliably obtained, and the insulating properties of the heat-resistant gas barrier layer 21 can also be reliably obtained.

[0049] Furthermore, in this embodiment, it is preferable to use a resin for the heat-resistant gas barrier layer 21 that has a melting point at least 10°C higher than the resin for the sealant layer 13. In other words, if the heat-resistant gas barrier layer 21 has a high melting point, even if the sealant layer 13 is melted when the exterior material 1 is heat-bonded, the melting and leakage of the heat-resistant gas barrier layer 21 can be prevented, thus ensuring that the gas permeation suppression effect and insulation properties of the heat-resistant gas barrier layer 21 are reliably obtained.

[0050] In this embodiment, it is preferable that the resin (resin film) constituting the sealant layer 13 is configured such that, with the original thickness being "db0" and the thickness obtained when pressed at 200°C, 0.2 MPa, and 5 seconds being "db1", the remaining percentage "db1 / db0" is 0.1 to 0.5, that is, satisfying the relationship B "0.5 ≥ db1 / db0 ≥ 0.1". This relationship B corresponds to a configuration in which the thickness reduction rate of the sealant layer 13 is 50 to 90% when the exterior material 1 is heat-bonded. In this embodiment, when the above relationship B is satisfied, when the exterior material 1 is heat-bonded and the solid battery body 5 is sealed, a certain thickness of the sealant layer 13 can be secured, so that insulation by the sealant layer 13 is also secured, and even if tab leads or foreign matter are present, the resin of the sealant layer 13 can flow into the gaps around their outer periphery, thereby ensuring sufficient sealing.

[0051] On the other hand, in this embodiment, as the adhesive (adhesive layer) for bonding each of the layers 11-13,21 of the exterior material 1, a curing type such as a two-component curing type or an energy ray (UV, X-ray, etc.) curing type can be used, and among these, urethane adhesives, olefin adhesives, acrylic adhesives, epoxy adhesives, etc. can be suitably used.

[0052] As described above, in the all-solid-state battery of this embodiment, since the above-mentioned unique heat-resistant gas barrier layer 21 is interposed between the metal foil layer 12 and the sealant layer 13 in the outer material 1, it is possible to reliably prevent the generated hydrogen sulfide gas from leaking to the outside. Furthermore, when sealing the solid-state battery body 5, even if the resin of the sealant layer 13 melts and leaks out when the sealant layer 13 of the outer material 1 is heat-bonded, reducing the insulating properties of the sealant layer 13, the heat-resistant gas barrier layer 21 remains, so the insulating properties can be reliably ensured by the heat-resistant barrier layer 21. [Examples]

[0053] [Table 1]

[0054] <Example 1> 1. Fabrication of exterior materials A 40 μm thick aluminum foil (A8021-O), which served as the metal foil layer 12, was coated on both sides with a chemical conversion treatment solution consisting of phosphoric acid, polyacrylic acid (acrylic resin), chromium(III) salt compound, water, and alcohol. The solution was then dried at 180°C to form a chemical conversion film. The amount of chromium deposited on this chemical conversion film was 10 mg / m² per side. 2 That was the case.

[0055] Next, a 15 μm thick biaxially oriented nylon 6 (ONY-6) film was dry-laminated (bonded) to one side (outer surface) of the chemically treated aluminum foil (metal foil layer 12) via a two-component curing urethane adhesive (3 μm) as a base layer 11.

[0056] Next, as shown in Table 1, a 9 μm thick PET film was bonded to the other side (inner surface) of the aluminum foil after dry lamination as a heat-resistant gas barrier resin layer 21 via a two-component curing urethane adhesive (3 μm).

[0057] Next, as shown in Table 1, a 20 μm thick CPP film containing a lubricant (such as erucic acid amide) was superimposed on the inner surface of the dry-laminated PET film (heat-resistant gas barrier layer 21) via a two-component curing urethane adhesive (3 μm) as the sealant layer 13. This film was then dry-laminated by sandwiching it between a rubber nip roll and a laminating roll heated to 100°C and pressing it together to obtain a laminate constituting the exterior material 1.

[0058] Next, this laminate was wound onto a roll shaft, and then aged at 40°C for 10 days to obtain the exterior material sample of Example 1.

[0059] 2. Measurement of H2S gas permeability, etc., of resin films The hydrogen sulfide (H2S) gas permeability of the PET film (heat-resistant gas barrier layer 21) and CPP film (sealant layer 13) used to prepare the exterior material samples in Example 1 was measured in accordance with JIS K7126-1, and the water vapor gas permeability of the PET film was also measured in accordance with JIS K7129-1 (humidity sensor method, 40°C, 90%Rh). The results are shown in Table 1.

[0060] 3. Measurement of the survival rate Two pieces of the exterior material sample from Example 1 were cut to a size of 15 mm in width and 150 mm in length. These two samples were then stacked so that their inner sealant layers were in contact with each other, and heat-sealed (heat-bonded) by heating one side using a heat-sealing device (TP-701-A) manufactured by Tester Industries Co., Ltd., under the conditions of heat-sealing temperature: 200°C, sealing pressure: 0.2 MPa (gauge indicated pressure), and sealing time: 2 seconds, to obtain a sample for measuring the remaining percentage of Example 1.

[0061] In this sample used for measuring the remaining percentage, the sealed portion was solidified with resin, cut to reveal the cross-section, and the cross-section was observed using a scanning electron microscope (SEM) to determine the thickness of the heat-resistant gas barrier layer 21 and the sealant layer 13, etc.

[0062] Based on the layer thickness after heat sealing and the layer thickness of the exterior material sample before heat sealing, the remaining percentage of the heat-resistant gas barrier layer 21 "da1 / da0" and the remaining percentage of the sealant layer 13 "db1 / db0" were measured (see relational equations A and B above). The results are shown in Table 1.

[0063] 4. Measurement of seal strength

[0064] [Table 2]

[0065] Two pieces of the exterior material sample from Example 1 were cut to a size of 15 mm in width and 150 mm in length. These two samples were then stacked so that their inner sealant layers were in contact with each other. Using a heat sealing device (TP-701-A) manufactured by Tester Industries Co., Ltd., a heat sealing (heat bonding) was performed by heating one side under the conditions of a heat sealing temperature of 200°C, a sealing pressure of 0.2 MPa (gauge indicated pressure), and a sealing time of 2 seconds, to obtain a sample for evaluating the seal strength of Example 1.

[0066] For this seal strength evaluation sample, the peel strength was measured using a Shimadzu Access Strograph (AGS-5kNX) in accordance with JIS Z0238-1998, when the inner sealant layers of the seal portion of the sample were peeled in a T-shape at a tensile speed of 100 mm / min. This was defined as the seal strength (N / 15 mm width). The results are shown in Table 2.

[0067] 5. Measurement of insulation resistance (evaluation of insulation properties) As shown in Figures 3 and 4, two pieces of exterior material sample 1 from Example 1 were cut to a size of 100 mm in length and 50 mm in width. These two exterior material samples 1,1 were placed on top of each other with their sealant layers 13 facing each other and in contact. Meanwhile, a tab lead 3 made of aluminum foil, 10 mm wide and 100 μm thick, was placed between the two exterior material samples 1,1, with tab films 31 made of acid-modified polypropylene film, 50 μm thick, placed on both sides of the tab lead 3. At this time, a portion of the tab lead 3 was placed between the two exterior material samples 1,1, and the remaining portion was pulled outwards from the edges of the two exterior material samples 1,1. These unbonded samples were heat-sealed from both the top and bottom surfaces of the exterior material samples 1,1 using a double-sided heating type heat sealer under the conditions of a seal width of 5 mm, 200°C, and 0.2 MPa for 2 seconds to obtain a sample for insulation evaluation.

[0068] In the plan view of the insulating properties evaluation sample in Figure 3, the heat-bonded portion (heat-sealed portion) 131 is hatched with diagonal lines to facilitate understanding of the invention. Also, in the cross-sectional view of the insulating properties evaluation sample in Figure 4, the description of the heat-resistant gas barrier layer 13 is omitted to make the structure easier to understand.

[0069] Next, as shown in Figure 3, at the longitudinal end of the insulating sample, the resin of the base layer 11 was partially peeled off to partially expose the aluminum foil of the metal foil layer 12, and electrical conductivity was ensured from the outside to the exposed portion 121 with the aluminum foil (metal foil layer 12).

[0070] Then, one terminal of the insulation resistance measuring device (HIOKI E.C. CORPORATION: part number "HIOKI3154") 6 was connected to the metal foil layer 12 on the exposed portion 121 of the insulation evaluation sample, and the other terminal was brought into contact with the tab lead 3 to form a circuit. After that, a voltage of 25V for 5 seconds was applied between the metal foil layer 12 and the tab lead 3 in that circuit, and the resistance value was measured to obtain the insulation resistance value. The results are shown in Table 2.

[0071] 6. Evaluation of H2S gas permeability of exterior materials Instead of aluminum foil, a copper foil (Cu foil) with a thickness of 9 μm was used to prepare the copper foil type exterior material sample 1 of Example 1 in the same manner as described above.

[0072] Two pieces of this copper foil-type outer packaging material sample were cut to a size of 30 mm x 50 mm. These two outer packaging material samples 1,1 were placed on top of each other with their sealant layers 13 facing each other. The three sides of the placed outer packaging material samples 1,1 were then sealed under the following conditions: heat seal temperature: 200°C, seal pressure: 0.2 MPa (gauge indicated pressure), and seal time: 2 seconds to create a three-sided bag. Subsequently, at one side (the 30 mm side) which is the opening of the three-sided bag, an injection needle was placed between the outer packaging material samples 1,1 and the opening was sealed under the same sealing conditions as above. H2S gas was then injected through the injection needle at a pressure of 0.1 MPa (the injection needle was placed on the 30 mm side).

[0073] Once the gas was sealed inside, the needle was slightly withdrawn to prevent gas leakage, and the area inside the tip of the needle was heat-sealed again under the same sealing conditions to completely seal the gas. After that, the needle was removed to create a gas-sealed bag.

[0074] The gas-filled bags were left to stand in a 40°C constant temperature bath for 7 days, after which the gas was released and the seal was removed for internal observation. Based on the observation, bags in which no change was observed in the Cu foil were evaluated as "○", and bags in which discoloration was observed in the seal or other areas were evaluated as "×". The results are shown in Table 2.

[0075] <Example 2> The sample for Example 2 was prepared in the same manner as in Example 1, except that a 3 μm thick PET film was used as the heat-resistant gas barrier layer 21 and a 30 μm thick CPP film was used as the sealant layer 13. The same measurements (evaluations) were then performed. The results are shown in Tables 1 and 2.

[0076] <Example 3> The sample for Example 3 was prepared in the same manner as in Example 1, except that a 15 μm thick PET film was used as the heat-resistant gas barrier layer 21, and the same measurements (evaluations) were performed. The results are shown in Tables 1 and 2.

[0077] <Example 4> The sample for Example 4 was prepared in the same manner as in Example 1, except that a PET film with a thickness of 25 μm was used as the heat-resistant gas barrier layer 21, and the same measurements (evaluations) were performed. The results are shown in Tables 1 and 2.

[0078] <Example 5> The sample for Example 5 was prepared in the same manner as in Example 1, except that a 15 μm thick film was used as the heat-resistant gas barrier layer 21, and the same measurements (evaluations) were performed. The results are shown in Tables 1 and 2.

[0079] <Example 6> The sample for Example 6 was prepared in the same manner as in Example 1, except that a 5 μm thick film was used as the heat-resistant gas barrier layer 21, and the same measurements (evaluations) were performed. The results are shown in Tables 1 and 2.

[0080] <Example 7> The sample for Example 7 was prepared in the same manner as in Example 1, except that a 40 μm thick film was used as the heat-resistant gas barrier layer 21, and the same measurements (evaluations) were performed. The results are shown in Tables 1 and 2.

[0081] <Example 8> The sample for Example 8 was prepared in the same manner as in Example 1, except that a 60 μm thick CPP film was used as the sealant layer 13, and the same measurements (evaluations) were performed. The results are shown in Tables 1 and 2.

[0082] <Example 9> The sample for Example 9 was prepared in the same manner as in Example 1, except that a 60 μm thick HDPE film was used as the sealant layer 13, and the same measurements (evaluations) were performed. The results are shown in Tables 1 and 2.

[0083] <Example 10> The sample for Example 10 was prepared in the same manner as in Example 1, except that a 60 μm thick LLDPE film was used as the sealant layer 13, and the same measurements (evaluations) were performed. The results are shown in Tables 1 and 2.

[0084] <Example 11> The sample for Example 11 was prepared in the same manner as in Example 1, except that a 10 μm thick CPP film was used as the sealant layer 13, and the same measurements (evaluations) were performed. The results are shown in Tables 1 and 2.

[0085] <Example 12> The sample for Example 12 was prepared in the same manner as in Example 1, except that a 20 μm thick cellophane film was used as the heat-resistant gas barrier layer 21 and a 10 μm thick CPP film was used as the sealant layer 13, and the same measurements (evaluations) were performed. The results are shown in Tables 1 and 2.

[0086] <Example 13> The sample for Example 13 was prepared in the same manner as in Example 1, except that a 10 μm thick polyvinylidene chloride (PVDC) film was used as the heat-resistant gas barrier layer 21, and the same measurements (evaluations) were performed. The results are shown in Tables 1 and 2.

[0087] <Example 14> The sample for Example 14 was prepared in the same manner as in Example 1, except that a 15 μm thick PVDC film was used as the heat-resistant gas barrier layer 21 and a 30 μm thick CPP film was used as the sealant layer 13, and the same measurements (evaluations) were performed. The results are shown in Tables 1 and 2.

[0088] <Example 15> The sample for Example 15 was prepared in the same manner as in Example 1, except that a 25 μm thick PVDC film was used as the heat-resistant gas barrier layer 21, and the same measurements (evaluations) were performed. The results are shown in Tables 1 and 2.

[0089] <Example 16> The sample for Example 16 was prepared in the same manner as in Example 1, except that a heat-resistant gas barrier layer 21 was formed by coating the other side (inner surface) of the aluminum foil for the metal foil layer with PVDC to a thickness of 2 μm. The same measurements (evaluations) were performed. The results are shown in Tables 1 and 2.

[0090] <Example 17> The sample for Example 17 was prepared in the same manner as in Example 1, except that a PVDC film with a thickness of 50 μm was used as the heat-resistant gas barrier layer 21, and the same measurements (evaluations) were performed. The results are shown in Tables 1 and 2.

[0091] <Comparative Example 1> The sample was prepared in the same manner as in Example 1, except that the heat-resistant gas barrier layer 21 was not formed, and the same measurements (evaluations) were performed. The results are shown in Tables 1 and 2.

[0092] <Comparative Example 2> A sample for Comparative Example 2 was prepared in the same manner as in Example 1, except that a 25 μm thick CPP film was used as the sealant layer 13 without forming a heat-resistant gas barrier layer 21, and the same measurements (evaluations) were performed. The results are shown in Tables 1 and 2.

[0093] <Comparative Example 3> A sample for Comparative Example 3 was prepared in the same manner as in Example 1, except that a 30 μm thick OPP film was used as the heat-resistant gas barrier layer 21, and the same measurements (evaluations) were performed. The results are shown in Tables 1 and 2.

[0094] <Overall assessment> As is clear from Table 2, the exterior material samples of Examples 1 to 17 related to the present invention were able to obtain excellent results in all evaluations of insulation and gas permeability. However, the exterior material sample of Example 16, which had a thin heat-resistant gas barrier layer 21, had slightly inferior insulation, and the exterior material sample of Example 17, which had a thick heat-resistant gas barrier layer 21, had slightly lower seal strength.

[0095] In contrast, the exterior material samples of Comparative Examples 1 to 3, which deviate from the gist of the present invention, did not yield satisfactory results in the evaluation of gas permeability, and some did not yield satisfactory results in the evaluation of insulating properties.

[0096] This application is accompanied by a priority claim from Japanese Patent Application No. 2021-131016, filed on August 11, 2021, and the disclosures thereof constitute a part of this application.

[0097] The terms and expressions used herein are for illustrative purposes only and not intended to be restrictive, and should be understood as not excluding any equivalents of the features shown and described herein, and allowing for various modifications within the claimed scope of this invention. [Industrial applicability]

[0098] The exterior material for all-solid-state batteries of this invention can be suitably used as a casing material for housing the solid-state battery body. [Explanation of symbols]

[0099] 1: Exterior materials 11: Base material layer 12: Metal foil layer 13: Sealant layer 21: Heat-resistant gas barrier layer 5: Solid-state battery unit

Claims

1. An outer casing material for an all-solid-state battery, comprising a base layer, a metal foil layer laminated on the inner surface side of the base layer, and a sealant layer laminated on the inner surface side of the metal foil layer, for enclosing a solid-state battery body, A heat-resistant gas barrier layer is provided between the metal foil layer and the sealant layer. The heat-resistant gas barrier layer has a hydrogen sulfide gas permeability of 15 {cc・mm / (m)} measured in accordance with JIS K7126-1. ２ It is composed of resins with a density of} D·MPa or less, The resin constituting the heat-resistant gas barrier layer has an initial thickness of "da0", and its thickness after being pressed under the conditions of 200°C, 0.2 MPa, and 5 sec is defined as "da1". 1 ≥ da1 / da0 ≥ 0.9 An outer casing material for all-solid-state batteries, characterized by being configured to satisfy the relationship equation.

2. The exterior material for an all-solid-state battery according to claim 1, wherein the heat-resistant gas barrier layer has a thickness of 3 μm to 50 μm.

3. The sealant layer has a hydrogen sulfide gas permeability of 100 {cc·mm / (m) ２ An outer casing material for an all-solid-state battery according to claim 1 or 2, which is composed of a resin of} or less (D·MPa).

4. The resin constituting the sealant layer has an original thickness of "db0", and its thickness after being pressed under the conditions of 200°C, 0.2 MPa, and 5 sec is defined as "db1". 0.5 ≥ db1 / db0 ≥ 0.1 An outer casing material for an all-solid-state battery according to claim 1 or 2, configured to satisfy the relationship.

5. The resin constituting the heat-resistant gas barrier layer has a water vapor permeability of 50 g / m³, measured in accordance with JIS K7129-1 (humidity sensor method, 40°C, 90% Rh). ２ An outer casing material for an all-solid-state battery according to claim 1 or 2, wherein the value is less than or equal to / day.

6. A solid-state battery characterized in that a solid-state battery body is enclosed in an outer casing material for a solid-state battery as described in claim 1 or 2.

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