Inter-cell structure

Abstract

Provided is an inter-cell structure which is suitable for maintaining a buffer function for relaxing stress from a lithium ion battery cell with high durability while achieving a size that is suited to the cell. Provided is an inter-cell structure for use in a battery module or a battery pack including a plurality of arrayed lithium ion battery cells, the inter-cell structure being disposed between adjacent cells among the plurality of cells. The inter-cell structure has: a bag body that defines a sealed space; and a fluid such as a gas and a porous sheet in the sealed space. The bag body is formed of a laminated film including a metal layer and a resin layer, and has a sealing end part in which the innermost layers of first and second film parts of the laminated film are joined to each other so as to seal the sealed space. The porous sheet is positioned at a distance from the sealing end part of the bag body. The bag body has, between the sealing end part and the porous sheet, a folded part in which the first and second film parts overlap with each other and are folded with the first film part being on the inner side.

Description

Inter-cell structure

[0001] The present invention relates to an inter-cell structure that is disposed between a plurality of arranged lithium ion battery cells.

[0002] Non-aqueous electrolyte secondary batteries such as lithium-ion secondary batteries are increasingly being used as power sources for electrically powered vehicles such as electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PEVs), and fuel cell vehicles (FCVs). Because these applications require extremely high output and capacity, they are used in the form of battery modules or battery packs that integrate battery cells (single cells).

[0003] It is known that cells of lithium-ion secondary batteries repeatedly expand during charging and contract during discharging, and research into the causes and solutions is ongoing. For example, Non-Patent Document 1 describes that the cause is an oxide coating formed due to a side reaction between silicon particles and the electrolyte, etc. As a countermeasure, a new antioxidant coating is used to suppress irreversible expansion of the material, thereby suppressing both electrode expansion and cycle degradation. Furthermore, for secondary batteries that experience significant expansion and contraction of battery cells during charging and discharging, Non-Patent Document 2, for example, discloses that the use of a binder with an adjusted elastic modulus suppresses electrode expansion and improves cycle characteristics.

[0004] Patent Document 1 also discloses that the elastic body that receives load from the electrode body of the secondary battery in the stacking direction of the electrode body also plays a role in absorbing pressure, and that by specifying the compressive elastic modulus of each member, it is possible to suppress an increase in resistance during high-rate charging and discharging and a decrease in capacity during charging and discharging cycles.

[0005] Japanese Patent Publication No. 2021-114361 Canadian Patent Application Publication No. 1190279

[0006] FY2015 Strategic Fundamental Technology Advancement Support Project, "Practical application of silicon-based high-capacity anode materials for lithium-ion batteries that suppress material expansion during charging", entrusted by the Kansai Bureau of Economy, Trade and Industry, entrusted to the Kyoto Advanced Technology Research Institute, Public Interest Incorporated Foundation, Development of binders for Si anodes and electrode expansion evaluation, JSR Corporation, JSR Technical Review No. 125 (March 2018) Effect of Pressure and Mechanical Properties of Laminated Separators on Electrode Reactions of Lithium Metal Negative Electrodes, Mie University Graduate School of Engineering, Department of Molecular Materials Engineering, Energy Conversion Chemistry Course, Shogo Kanamori / Author March 2019 (March 2020) Investigation of Constant Stack Pressure on Lithium-Ion Battery Performance, High Voltage Energy Storage Group, School of Engineering, Computing, and Mathematics, Oxford Brookes University, Oxford, UK, OX33 1HX, Aiden Leonarda, Brady Plandena, Katie Lukowa / author (2023 / 1)

[0007] As mentioned above, lithium-ion battery cells repeatedly expand during charging and contract during discharging, and also undergo irreversible expansion. Therefore, when integrating cells into a battery pack or a battery module (hereinafter collectively referred to as a "battery module, etc.") that constitutes the battery pack, it is necessary to consider dimensional changes in the cell stacking direction and generated pressure. It has also been reported that the efficiency of lithium-ion battery cells is improved when a certain amount of pressure is applied to the cell itself (e.g., Patent Document 2, Non-Patent Document 3, Non-Patent Document 4). Additionally, in battery modules, etc., components and structures attached to battery cells are strongly required to be no larger than the battery cell dimensions (height and width perpendicular to the stacking direction of the battery cells) from the standpoints of ease of assembly during the manufacturing process of the module, etc., and the contact of the battery cells with the cooling plate. In other words, components and structures attached to the battery cells are subject to structural size constraints imposed by the battery module, etc.

[0008] Therefore, an object of the present invention is to provide an inter-cell structure that is suitable for achieving a size appropriate for a lithium-ion battery cell while durably maintaining the buffering function of alleviating stress from the cell.

[0009] This specification provides an inter-cell structure that is disposed between adjacent cells in a battery module or battery pack including an array of lithium-ion battery cells. The inter-cell structure includes a pouch that defines an enclosed space, and a porous sheet and a fluid, including at least a gas, within the enclosed space. The pouch is formed from a laminated film including a metal layer and a resin layer, the laminated film including a first film portion and a second film portion, and has a sealing edge where the innermost layers of the first film portion and the second film portion are joined to each other, sealing the enclosed space. The porous sheet is located away from the sealing edge of the pouch. The pouch has a folded portion between the sealing edge and the porous sheet, where the first film portion and the second film portion overlap and are folded back with the first film portion facing inward.

[0010] In the intercellular structure having the above configuration, a fluid (including gas) is contained in the sealed space within the bag, allowing the structure to function as a fluid spring (gas spring) (realizing an elastic thickness fluctuation mechanism), and in addition, the repulsive force of the porous sheet within the sealed space can be utilized in the thickness fluctuation mechanism. Such an intercellular structure can change in thickness with good follow-up in response to repeated expansion and contraction of the cells, thereby durably exhibiting a buffering function that relieves stress from the cells.

[0011] In addition, in the intercellular structure having the above configuration, the porous sheet is positioned away from the sealing edge within the bag. In the manufacturing process of such an intercellular structure, for example, when the porous sheet is placed between the laminated films for forming the bag and the opposing surfaces of the laminated films are sealed around the porous sheet to form the sealing edge, damage and contamination of the porous sheet (which is away from the sealing edge) can be prevented (forming the sealing edge at the point of contact with the porous sheet in the bag can cause damage and contamination of the porous sheet). Preventing damage and contamination of the porous sheet helps to achieve good cushioning function and ensure the durability of the cushioning function in the intercellular structure.

[0012] Additionally, in the inter-cell structure described above, the pouch has a folded portion between the sealing edge and the porous sheet, where the first film portion and the second film portion are folded back while overlapping. This inter-cell structure can minimize an increase in the effective outer size of the pouch while ensuring a sufficient dimension (seal width) for the sealing edge to prevent leakage of fluid (including gas) from the pouch. Having the folded portion in the pouch helps ensure that the pouch of the inter-cell structure disposed in the battery module or battery pack is sized appropriately for the battery cells (not too large for the battery cells). A configuration in which the pouch has the folded portion between the sealing edge and the porous sheet is suitable for ensuring a larger area ratio of the porous sheet to the outer size (effective outer size) of the pouch after folding, compared to a configuration in which the pouch has a folded portion at the sealing edge (i.e., a configuration in which the pouch is folded back within the width of the sealing edge). In other words, this helps to realize a size of the pouch of the inter-cell structure that corresponds to the battery cell while allowing a porous sheet with a larger size (area in plan view) to be accommodated in the pouch without contacting the sealing edge during the manufacturing process. The greater the area ratio of the porous sheet to the effective outer size of the pouch, the easier it is to realize a good cushioning function and improve the durability of the cushioning function.

[0013] As described above, the inter-cell structure can be sized to match a lithium-ion battery cell, while also durably maintaining the buffering function of absorbing stress from the cell.

[0014] In some preferred embodiments, the outer surface of the first film portion at the folded-back portion has a radius of curvature R of 0.30 mm or more. Such a configuration is advantageous from the viewpoint of suppressing damage to the sealing edge and its vicinity in the bag body when the inter-cell structure repeatedly changes in thickness.

[0015] In some preferred embodiments, the outer surface of the first film portion in the folded portion has a radius of curvature R that is equal to or less than half the uncompressed thickness of the inter-cell structure. Such a configuration is useful for making the inter-cell structure thinner.

[0016] In some embodiments, the intercell structure may further include a fastening means for fastening the folded portion and / or the sealing edge to portions of the bag other than the folded portion and the sealing edge, which helps to prevent the folded portion from opening (deforming the first and second film portions in a direction from the folded shape back to the flat shape).

[0017] In some preferred embodiments, the surface area A [m ２ and the volume V [L] of the gas contained in the sealed space, the amount of gas G calculated by the following formula: G = V / (A / 2); is 1.0 L / m ２ This configuration makes it easier to achieve a buffer function that allows the thickness to change with good follow-up in response to repeated expansion and contraction of the cells.

[0018] The porous sheet accommodated in the sealed space of the bag may be, for example, a sheet-like molded body containing inorganic fibers, a foam sheet, or a combination thereof. In some preferred embodiments, the intercellular structure includes at least a sheet-like molded body containing inorganic fibers (hereinafter also referred to as an inorganic fiber-containing sheet) as the porous sheet. A configuration in which an inorganic fiber-containing sheet is accommodated together with gas in the sealed space partitioned by the bag can effectively improve the durability of the buffer function. As the inorganic fiber-containing sheet, for example, a sheet-like molded body containing one or more materials selected from the group consisting of glass wool, long glass fiber, glass fiber mat, glass fiber needle mat, rock wool, alkaline earth silicate (AES) fiber, and AES wool can be preferably used.

[0019] In some embodiments, the porous sheet accommodated in the sealed space of the bag may include a sheet-like molded product containing inorganic particles and inorganic fibers (hereinafter also referred to as an inorganic particle / inorganic fiber-containing sheet). As the porous sheet, an inorganic particle / inorganic fiber-containing sheet and an inorganic fiber-containing sheet that does not contain inorganic particles may be used in combination.

[0020] The gas contained in the sealed space is preferably mainly composed of a non-flammable gas, for example, more than 50% (by volume) of the gas is preferably composed of one or more gases selected from the group consisting of nitrogen, argon, carbon dioxide, neon, helium, krypton, and xenon.

[0021] Appropriate combinations of the elements described in this specification may also be included within the scope of the invention for which patent protection is sought by this patent application.

[0022] 1 is a cross-sectional view schematically showing an inter-cell structure according to one embodiment. FIG. 2 is an enlarged cross-sectional view schematically showing a portion of the inter-cell structure shown in FIG. 1. FIG. 3 is a perspective view schematically showing an example of a battery module in which the inter-cell structure shown in FIG. 1 is disposed between cells of a lithium ion battery. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 3. (i) to (iii) are explanatory views schematically showing an example of a manufacturing process for an inter-cell structure. FIG. 5 is a cross-sectional view schematically showing a folded portion and its vicinity of an inter-cell structure according to another embodiment. FIG. 6 is a cross-sectional view schematically showing a folded portion and its vicinity of an inter-cell structure according to another embodiment. FIG. 7 is a cross-sectional view schematically showing a folded portion and its vicinity of an inter-cell structure according to another embodiment. FIG. 8 is a cross-sectional view schematically showing a folded portion and its vicinity of an inter-cell structure according to another embodiment. FIG. 9 is a cross-sectional view schematically showing a folded portion and its vicinity of an inter-cell structure according to another embodiment.

[0023] Preferred embodiments of the present invention are described below. Matters necessary for carrying out the present invention other than those specifically mentioned in this specification can be understood by those skilled in the art based on the teachings for carrying out the invention described in this specification and the common general technical knowledge at the time of filing. The present invention can be carried out based on the contents disclosed in this specification and the common general technical knowledge in the relevant field. Furthermore, in the following drawings, components and parts that perform the same function may be denoted by the same reference numerals, and redundant explanations may be omitted or simplified. Furthermore, the embodiments shown in the drawings are schematic for the purpose of clearly explaining the present invention, and do not necessarily accurately represent the size or scale of the actual product provided.

[0024] In this specification, unless otherwise specified, the term "to" indicating a range of values ​​means that the range includes the values ​​before and after it as the lower and upper limits.

[0025] In addition, in this specification, "weight" may be read as "mass." For example, "% by weight" may be read as "% by mass," and "parts by weight" may be read as "parts by mass."

[0026] FIG. 1 is a cross-sectional view schematically illustrating an inter-cell structure 1 according to one embodiment of the inter-cell structure disclosed in this specification. FIG. 2 is an enlarged cross-sectional view schematically illustrating a portion of the inter-cell structure 1. The inter-cell structure 1 includes a bag 10 defining an enclosed space, a fluid 20 in the enclosed space, and a porous sheet 30. The fluid 20 includes at least a gas. Such an inter-cell structure 1 is disposed between adjacent cells in a battery module or battery pack including an array of lithium-ion battery cells. The target cells are not limited to prismatic cells and may be, for example, laminated cells or cylindrical cells. The shape of the inter-cell structure 1 can be appropriately adopted depending on the type of cell. Furthermore, target devices for the battery include electric vehicles (EVs), hybrid vehicles (HVs), plug-in hybrid vehicles (PHVs), and other electric vehicles; portable electronic devices such as mobile terminals, mobile phones, and laptop computers; and wearable devices.

[0027] FIG. 3 is a perspective view schematically illustrating an example of a battery module in which an intercell structure 1 is disposed between cells, and FIG. 4 is a cross-sectional view taken along line IV-IV of FIG. 3 . As shown in FIG. 3 , a battery module 80 includes a plurality of lithium-ion battery cells (here, rectangular cells) 81 arranged in the thickness direction, with an intercell structure 1 disposed between each of the battery cells 81. The plurality of battery cells 81 arranged in this manner with the intercell structure 1 sandwiched between them are typically constrained by applying a pressing force (compressive force) in the thickness direction via restraint plates 82 a, 82 a disposed at both ends, and are housed in a battery case 83 for use. By sandwiching the intercell structure 1 between two adjacent battery cells 81, 81 as shown in FIG. 4 , the intercell structure 1 can exhibit a buffering function between the battery cells 81, 81, capable of appropriately adjusting its thickness in response to repeated expansion and contraction of the cells 81, 81, due to the fluid spring (gas spring) provided by the gas-containing fluid 20 and the resilience of the porous sheet 30.

[0028] Furthermore, the intercell structure 1 disclosed herein may be disposed between adjacent cells alone or in two or more. When two or more intercell structures 1 are disposed, they are preferably disposed so as not to overlap in the cell arrangement direction. By disposing two or more intercell structures 1 between cells in this manner, even if the airtightness of the sealed space of the bag body of one intercell structure 1 is accidentally lost, the presence of the remaining intercell structures 1 can suppress a decrease in the function as a fluid spring. From the viewpoint of ease of assembly of a battery module, etc., the number of intercell structures 1 disposed between adjacent cells is suitably 10 or less, preferably 6 or less, and may be 4 or less, or 2 or less. The total number of bags 10 included in those intercell structures 1 is suitably 20 or less, preferably 12 or less, and may be 8 or less, 4 or less, or 2 or less.

[0029] <Bag> The bag 10 of the inter-cell structure 1 is formed from a laminated film including a metal layer and a resin layer. That is, the bag 10 uses the laminated film as its constituent material (bag material). The laminated film forming the bag 10 includes a film portion 10a (first film portion) and a film portion 10b (second film portion). The bag 10 has a sealing edge 10E where the innermost layers of the film portions 10a and 10b are joined together to seal the sealed space. The bag 10 also has a folded portion 10X where the film portions 10a and 10b are folded back while overlapping. Using a laminated film including a metal layer and a resin layer as the bag material makes it easy to form a bag 10 that combines the gas barrier properties provided by the metal layer with the ease of deformation (cushioning) and formability provided by the resin layer. Figure 2 shows an example of a laminated film having a three-layer structure including a resin layer 11, a resin layer 12, and a metal layer 13 therebetween (the layer structure of the laminated film is not limited to the structure shown in Figure 2).

[0030] The type of metal layer contained in the laminate film is not particularly limited and may be, for example, a metal layer (metal foil, metal film, etc.) such as an aluminum layer, a copper layer, or a stainless steel layer. The number of metal layers contained in the laminate film may be one layer, or two or more layers (e.g., 2 to 5 layers or 2 to 3 layers). In a laminate film containing two or more metal layers, the types of these metal layers may be the same or different. In some embodiments, a configuration in which the laminate film contains one metal layer may be preferably adopted, from the viewpoint of easily exhibiting good gas barrier properties and strength while suppressing an increase in the total thickness of the laminate film.

[0031] The thickness of the metal layer (in a laminate film including two or more metal layers, the thickness of each metal layer) may be, for example, within a range of approximately 0.1 μm to 150 μm. In some embodiments, from the viewpoint of gas barrier properties and strength, the thickness of the metal layer is suitably 1 μm or more, advantageously 3 μm or more, preferably 5 μm or more, may be 10 μm or more, may be 20 μm or more, or may be 30 μm or more. In some embodiments, from the viewpoint of suppressing heat conduction through the bag body 10, the thickness of the metal layer is suitably 100 μm or less, advantageously 80 μm or less, preferably 60 μm or less, may be 50 μm or less, may be 40 μm or less, may be 30 μm or less, or may be 20 μm or less. The thickness of the metal layer can be determined by averaging values ​​measured at several locations (e.g., 10 locations) using a thickness gauge (e.g., a digital thickness gauge H-1A (measuring probe Φ5 mm) manufactured by Ozaki Manufacturing Co., Ltd.). When the nominal value of the thickness of the metal layer of the laminated film is provided by the manufacturer or the like, this nominal value may be used.

[0032] The type of resin layer contained in the laminate film is not particularly limited, and examples thereof include resin layers (films, coatings, etc.) such as polyester layers (polyethylene terephthalate (PET) layers, polybutylene terephthalate layers, polyethylene naphthalate layers, etc.), polyimide layers, polycarbonate (including flame-retardant polycarbonates), nylon layers, polypropylene (PP) layers, polyethylene (PE) layers, ethylene-vinyl acetate copolymer resin (EVA) layers, acrylic resin layers (typically polymethyl methacrylate layers), ethylene-vinyl alcohol copolymer resin (EVOH), and polyvinylidene chloride (PVDC). Examples of the PET layer include oriented polyethylene terephthalate films and amorphous polyethylene terephthalate (A-PET) films. Examples of the nylon layer include biaxially oriented nylon (ONY) films and unoriented nylon films. Examples of the PP layer include unoriented polypropylene (CPP) films and biaxially oriented polypropylene (OPP) films. Examples of the PE layer include a linear low-density polyethylene (LLDPE) layer, a low-density polyethylene (LDPE) layer, a high-density polyethylene (HDPE) layer, etc. The number of resin layers contained in the laminate film may be one layer, or two or more layers (e.g., 2 to 7 layers, 2 to 5 layers, 2 to 4 layers, or 2 to 3 layers). In a laminate film containing two or more resin layers, the types of these resin layers may be the same or different.

[0033] The thickness of the resin layer (in a laminate film including two or more resin layers, the thickness of each resin layer) may be, for example, within a range of approximately 0.1 μm to 500 μm. In some embodiments, from the viewpoint of suppressing an increase in the total thickness of the laminate film, the thickness of the resin layer is preferably 450 μm or less, more preferably 350 μm or less, and may be 250 μm or less, 200 μm or less, 150 μm or less, or 100 μm or less. In some embodiments, from the viewpoint of facilitating the appropriate performance of the function of each resin layer, the thickness of the resin layer may be, for example, 1 μm or more, 3 μm or more, 5 μm or more, or 10 μm or more. The thickness of the resin layer can be measured at several locations (e.g., 10 locations) using a thickness measuring device (e.g., a digital thickness gauge H-1A (measuring probe Φ5 mm) manufactured by Ozaki Manufacturing Co., Ltd.) and the average value of the values ​​measured at several locations (e.g., 10 locations) can be used. When the nominal value of the thickness of the resin layer of the laminate film is provided by the manufacturer, that nominal value may be used.

[0034] The order of lamination of the metal layer and resin layer contained in the laminate film is not particularly limited. From the viewpoint of ease of forming the bag body 10, it is preferable that at least the innermost layer be a resin layer. In some preferred embodiments, the innermost layer may be a heat-seal layer that is welded when forming the bag body 10 from the laminate film. The heat-seal layer may be provided over the entire area of ​​the laminate film, or may be provided in a partial region of the laminate film that includes the heat-sealed portion. Non-limiting examples of resin layers that can be used as the innermost resin layer include a PP layer (e.g., a CPP layer or an OPP layer), a PE layer (e.g., an LLDPE layer, an LDPE layer, or an HDPE layer), an EVA layer, an EVOH layer, a PVDC layer, and a PET layer (e.g., an A-PET layer). From the viewpoints of ease of heat sealing and strength, a CPP layer and an LLDPE layer are preferred resin layers. Furthermore, from the viewpoints of low gas permeability, an EVOH layer and a PVDC layer are preferred resin layers. The materials of the innermost layers joined at the sealing end 10E may be the same or different. The use of the same material for the innermost layers can be advantageous in terms of heat sealability.

[0035] The thickness of the innermost layer of the laminated film may be, for example, 40 μm or more. In some embodiments, from the viewpoint of the strength and durability of the sealing edge 10E where the innermost layers are joined, the thickness is preferably 50 μm or more (e.g., greater than 50 μm), more preferably 60 μm or more, 70 μm or more, 80 μm or more, 100 μm or more, or 125 μm or more. The thickness of the innermost layer of the laminated film may be, for example, 400 μm or less, preferably 300 μm or less, more preferably 250 μm or less, 200 μm or less, or 150 μm or less. Having an innermost layer that is not too thick is advantageous from the viewpoint of reducing the thickness of the sealing layer at the sealing edge 10E where the innermost layers are joined and suppressing gas leakage through the sealing layer. In some preferred embodiments, the thickness of the innermost layer may be, for example, 120 μm or less, 110 μm or less, 100 μm or less, or 90 μm or less.

[0036] In some embodiments, a laminate film having a configuration in which a first resin layer, a second resin layer, a metal layer, and a third resin layer are laminated in this order from the outside of the bag body 10 can be preferably used. The first resin layer can be a layer that forms the outer surface of the bag body 10 formed using the laminate film. The first resin layer can be useful for imparting surface insulation and antifouling properties to the bag body 10 and protecting the metal layer from deterioration and damage. The second resin layer can be useful for ensuring adhesion between the first resin layer and the metal layer. Non-limiting suitable examples of the first resin layer include a PET layer, etc. Non-limiting suitable examples of the second resin layer include a nylon layer (e.g., a biaxially oriented nylon (ONY) layer), etc. The metal layer can be, for example, an aluminum layer, although not particularly limited thereto. The third resin layer can be the innermost layer of the laminate film.

[0037] The laminate film may include layers (optional layers) other than the resin layer and the metal layer as optional components. The optional layers may include, for example, fabric layers such as glass cloth, silica cloth, aramid cloth, resin-impregnated glass cloth, resin-impregnated silica cloth, and resin-impregnated aramid cloth, colored layers, antistatic layers, adhesive layers, etc. The number of optional layers included in the laminate film may be one layer, or two or more layers (for example, about 2 to 8 layers).

[0038] In some embodiments, the laminate film forming the bag body 10 is preferably resistant to expansion and contraction deformation, has a high Young's modulus, and is highly rigid, from the viewpoint of controllability of shape change due to repeated cell expansion and contraction. For example, the Young's modulus of the laminate film is preferably greater than 25 MPa, more preferably 100 MPa or more, even more preferably 500 MPa or more, and may be 800 MPa or more, 1 GPa or more, or 1.2 GPa or more. The upper limit of the Young's modulus is not particularly limited. In some embodiments, from the viewpoint of formability and cushioning properties of the bag body 10, the Young's modulus of the laminate film is suitably 5 GPa or less, preferably 3 GPa or less, more preferably 2 GPa or less, and may be 1.7 GPa or less, 1.5 GPa or less, or 1.3 GPa or less. The Young's modulus (tensile modulus) is determined by measurement in an environment of 25°C and 50% RH in accordance with JIS-K-7161. The pulling speed during measurement is appropriately set depending on the material and structure of the laminated film, the size of the measurement sample, etc., and can be, for example, 5 mm / min. When a nominal value of Young's modulus is provided by a manufacturer or the like, this nominal value may be used.

[0039] Furthermore, from the viewpoint of the strength and durability of the bag body 10, the tensile strength of the laminate film forming the bag body 10 is suitably 10 N / 10 mm or more, preferably 30 N / 10 mm or more, more preferably 50 N / 10 mm or more, and may be 60 N / 10 mm or more, or even 70 N / 10 mm or more. The upper limit of the tensile strength of the laminate film is not particularly limited. In some embodiments, from the viewpoint of the formability and cushioning properties of the bag body 10, the tensile strength of the laminate film may be, for example, 300 N / 10 mm or less, 200 N / 10 mm or less, or even 100 N / 10 mm or less. The tensile strength is determined in accordance with JIS K 7127 or JIS C 2318-72 in an environment of 25°C and 50% RH. The pulling speed during measurement is appropriately set depending on the material and structure of the laminate film, the size of the measurement sample, etc., and can be, for example, 5 mm / min. If a nominal value of the tensile strength is provided by the manufacturer, etc., that nominal value may be used.

[0040] The thickness of the laminate film forming the bag body 10 is not particularly limited and may be, for example, within a range of approximately 60 μm to 1000 μm. In some embodiments, the thickness of the laminate film is preferably 65 μm or more, more preferably 75 μm or more, and may be 85 μm or more, 95 μm or more, 100 μm or more, 105 μm or more, or 110 μm or more. In some embodiments, the thickness of the laminate film is suitably, for example, 800 μm or less, preferably 600 μm or less, more preferably 500 μm or less, may be 400 μm or less, may be 300 μm or less, may be 250 μm or less, 200 μm or less, or may be 160 μm or less. When the thickness of the laminate film forming the bag body 10 is within the above range, it is easy to appropriately achieve both the ease of deformation (shock-absorbing properties) that can easily absorb thickness fluctuations associated with expansion and contraction between cells and the mechanical strength of the bag body 10. The thickness of the laminated film can be the average value of measurements taken at several locations (for example, 10 locations) using a thickness measuring device (for example, a digital thickness gauge H-1A (measuring probe Φ5 mm) manufactured by Ozaki Seisakusho). When the nominal value of the thickness of the laminated film is provided by the manufacturer, etc., this nominal value may be used.

[0041] The number (sheets) of bag materials used to form the bag body 10 is usually one or more, preferably two or more, and usually five or less, preferably four or less, and more preferably three or less. The two or more bag materials may be, for example, two or more sheets of laminate film, or one sheet of laminate film may be folded over to form two sheets. When folded over in this manner, the number of bag materials is considered to be two. Furthermore, when a laminate film formed into a cylindrical shape is used as the bag material, the number of bag materials is also considered to be two.

[0042] The bag body 10 can be formed, for example, by placing two sheets of bag material (laminated film) facing each other and sealing the opposing surfaces of the bag material in a circular fashion. The method for sealing the opposing surfaces of the bag material is not particularly limited, and examples include welding methods such as heat welding and ultrasonic welding; and bonding methods using adhesives or pressure-sensitive adhesives. The welding may be performed by directly welding the resin of the bag material (typically the innermost resin layer of the laminated film) or by providing a separate resin layer for welding. When one sheet of bag material is folded back to form two bags, sealing the edges corresponding to the folded portions can be omitted as appropriate. When a laminated film formed into a cylindrical shape is used as the bag material, an airtight space can be formed by sealing both open ends of the tube, and sealing the edges corresponding to one or both widthwise ends of the tube can be omitted as appropriate.

[0043] The sealing between the opposing surfaces of the bag material forms a sealing edge 10E in which the innermost layers of the bag material (laminate film) are joined together to seal the sealed space. In this sealing edge 10E, the sealed space within the bag body 10 is separated from the outside by a seal layer (seal layer 10e in FIG. 2 ) formed by integrating the innermost layers of the two opposing laminate films (if the sealing edge 10E is formed using a welding resin layer separate from the laminate film, the innermost layer and the welding resin layer). From the viewpoint of easily ensuring an appropriate seal strength at the sealing edge 10E, the thickness of the seal layer is suitably more than 100 μm, preferably 110 μm or more or 120 μm or more, more preferably 130 μm or more, and may be 140 μm or more, 150 μm or more, 160 μm or more, 200 μm or more, or 250 μm or more. In some embodiments, the thickness of the sealing layer is suitably about 600 μm or less, preferably 500 μm or less, and may be 400 μm or less, 350 μm or less, 300 μm or less, 250 μm or less, 200 μm or less, 180 μm or less, 160 μm or less, 150 μm or less, or 140 μm or less. Not having a sealing layer that is too thick is advantageous from the viewpoint of suppressing gas leakage through the sealing layer.

[0044] The width of the sealing layer (sealing layer 10e in FIG. 2 ) is preferably 5.0 mm or more, more preferably 7.0 mm or more, and even more preferably 9.0 mm or more, and may be 10.0 mm or more, 11.0 mm or more, 12.0 mm or more, 14.0 mm or more, or 16.0 mm or more, from the viewpoint of suppressing gas leakage through the sealing layer. In some embodiments, the width of the sealing layer is preferably 20.0 mm or less, more preferably 16.0 mm or less, and even more preferably 12.0 mm or less, and may be 10.0 mm or less, or may be 9.0 mm or less, from the viewpoint of miniaturizing the inter-cell structure 1. Here, the "width" of the sealing layer refers to the length in the direction (width direction) perpendicular to the extension direction of the sealing layer along the sealed space.

[0045] In the technology disclosed herein, the method for realizing a configuration in which a fluid 20 containing a gas (described later) is contained within a sealed space partitioned by a bag 10 is not particularly limited. For example, the sealed space may be formed in a state in which the gas is already contained therein, or the gas may be generated within the sealed space after the sealed space is formed, or an intermediate or combined method thereof may be employed. Examples of methods for generating gas within a sealed space include methods that generate gas through a chemical reaction. Specific examples include a method of generating carbon dioxide gas by reacting sodium bicarbonate with an aqueous citric acid solution, or a method of generating carbon dioxide gas by reacting an isocyanate with water. Either one of the components of the sodium bicarbonate or the aqueous citric acid solution (e.g., sodium bicarbonate) may be encapsulated, or each component may be encapsulated separately, and the capsules may be broken by pressure or the like at an appropriate time to bring the two components into contact with each other to generate carbon dioxide. The same applies to a combination of isocyanate and water. With this configuration, the bag can be stored or mailed in a compact form before the two components are brought into contact, and carbon dioxide gas can be generated at the appropriate time to inflate the bag, allowing it to function as a gas spring.

[0046] The number of sealed spaces in one bag body 10 may be one or two or more. A bag body 10 having two sealed spaces can be formed, for example, by arranging two rectangular bag materials (laminated films) facing each other, sealing the bag materials in a ring shape along their outer edges to form one sealed space, and then sealing the longitudinal center portion across the width to divide the single sealed space into two. With an inter-cell structure 1 including a bag body 10 having two or more sealed spaces, even if the hermeticity of one sealed space is accidentally impaired, the presence of the remaining sealed spaces can suppress a decrease in the function as a fluid spring. From the standpoints of ease of manufacturing the bag body 10 and space utilization efficiency, the number of sealed spaces in one bag body 10 is suitably 10 or less, preferably 6 or less, and may be 4 or less, or 2 or less. In some embodiments, a configuration in which one sealed space in one bag body 10 is included may be preferably adopted.

[0047] 2, the bag body 10 has a folded portion 10X between the sealing end portion 10E and the porous sheet 30. The folded portion 10X is a portion where the film portions 10a and 10b, in which the innermost layers of the laminated film in the bag body 10 are not joined, overlap and are folded back with the film portion 10a on the inside. From the viewpoint of suppressing the occurrence of cracks at and near the folded portion 10X of the bag body 10, the radius of curvature R of the surface 10S (shown in FIG. 2), which is the outer surface of the film portion 10a at the folded portion 10X, is suitably 0.30 mm or more, advantageously 0.40 mm or more, preferably 0.45 mm or more (e.g., greater than 0.45 mm), more preferably 0.50 mm or more, and may be 0.53 mm or more, 0.55 mm or more, or 0.57 mm or more (if the radius of curvature R is too small, the tensile load applied to the outer surface of the laminated film forming the folded portion 10X becomes large, and cracks tend to occur more easily in the metal layer where metal fatigue may accumulate when the thickness of the bag body 10 is repeatedly changed (expanded and contracted). In some embodiments, the radius of curvature R of the surface 10S is preferably 1.00 mm or less, more preferably 0.90 mm or less, and may be 0.80 mm or less, 0.75 mm or less, or 0.70 mm or less. Having the radius of curvature R of the surface 10S not be too large is advantageous for reducing the thickness of the folded-back portion 10X, and therefore helps to reduce the thickness of the inter-cell structure 1. From the perspective of reducing the thickness of the inter-cell structure 1, it is preferable that the surface 10S of the film portion 10a in the folded-back portion 10X have a radius of curvature R that is equal to or less than half the unpressurized thickness (described below) of the inter-cell structure 1.

[0048] The intercellular structure 1 may include a fixing means for fixing the folded portion 10X and / or the sealing edge 10E to a portion of the bag body 10 other than the folded portion 10X and the sealing edge 10E. Such a fixing means helps to prevent the folded portion 10X from opening (i.e., the film portions 10a, 10b from deforming in a direction returning from a folded shape to a flat shape). A suitable fixing means may be, for example, a single-sided adhesive tape. For example, the adhesive surface of the single-sided adhesive tape may be attached to the surface of the region of the bag body 10 where the film portions 10a, 10b are not joined (main region) and to the surface of the sealing edge 10E on the film portion 10b side, thereby fixing the sealing edge 10E to the main region of the bag body 10.

[0049] In this embodiment, the inter-cell structure 1 includes a pressure-sensitive adhesive layer 41 as a folded spacer 40. The folded spacer 40 has a predetermined thickness and is a member for adjusting the radius of curvature R of the folded portion 10X by utilizing the thickness. In this embodiment, the pressure-sensitive adhesive layer 41 as the folded spacer 40 is disposed along the sealing edge 10E of the bag body 10, and the folded portion 10X is folded along the pressure-sensitive adhesive layer 41. By selecting the thickness of the folded spacer 40, the radius of curvature R of the surface 10S of the folded portion 10X that is folded along the folded spacer 40 can be adjusted. From the viewpoint of suppressing the occurrence of cracks in and near the folded portion 10X of the bag body 10, the thickness of the folded spacer 40 is suitably 0.70 mm or more, advantageously 0.80 mm or more, preferably 0.90 mm or more (e.g., greater than 0.90 mm), more preferably 1.00 mm or more, and may be 1.06 mm or more, 1.10 mm or more, or 1.14 mm or more. In some embodiments, the thickness of the folded spacer 40 is preferably 2.00 mm or less, more preferably 1.80 mm or less, and may be 1.60 mm or less, 1.50 mm or less, or 1.40 mm or less. Not making the thickness of the folded spacer 40 too large is advantageous for making the folded portion 10X thinner, and therefore helps make the inter-cell structure 1 thinner.

[0050] In this embodiment, the adhesive layer 41 of the folded spacer 40 also serves as a fixing means for fixing the folded portion 10X and / or the sealing edge 10E to portions of the bag body 10 other than the folded portion 10X and the sealing edge 10E. Because the folded spacer 40 also serves as such a fixing means, opening of the folded portion 10X (deformation of the film portions 10a, 10b in a direction returning from a folded shape to a flat shape) is suppressed. Double-sided adhesive tape, for example, can be suitably used as a constituent material of the adhesive layer 41 (folded spacer 40 also serving as fixing means). The adhesive layer 41 may be formed using a single sheet of double-sided adhesive tape of a predetermined thickness, or two or more sheets of double-sided adhesive tape of a predetermined thickness may be stacked to form the adhesive layer 41. This forming method allows the adhesive layer 41 (folded spacer 40) to be formed with high thickness accuracy.

[0051] <Fluid> As described above, the fluid 20 and the porous sheet 30 are contained in the sealed space partitioned by the bag body 10. Here, the fluid 20 includes at least a gas. That is, the sealed space contains at least a gas and the porous sheet 30. By containing a gas in the sealed space within the bag body 10, the intercellular structure 1 can function as a gas spring, making it easier to realize an intercellular structure 1 that exhibits high compliance with repeated cell expansion and contraction, etc. Here, "containing at least a gas" as the fluid 20 means that the fluid 20 contains at least one gas component under conditions of 1 atmosphere, 23°C, and a relative humidity of 50% RH. The components contained in the fluid 20 contained in the sealed space can be determined by opening the sealed space under the above conditions, recovering the contents, and analyzing their composition. The analysis can be carried out by a conventional method. For example, gas chromatography or infrared absorption spectroscopy (IR) can be applied to the analysis of gases, and IR, nuclear magnetic resonance analysis (NMR), liquid chromatography, etc. can be applied to the analysis of liquids and solids.

[0052] Here, "sealed" means that leakage of the fluid 20 contained in the sealed space to the outside of the bag body 10 is practically sufficiently restricted. For example, in the case of gas, in a sealability test in which the bag body is left at 40°C under atmospheric pressure for 30 days, it is appropriate that the volume of the gas contained in the sealed space decreases by 1% or less, preferably 0.5% or less, and more preferably 0.1% or less.

[0053] The gas contained in the sealed space may be one component or two or more components. The gas is not particularly limited, and any gas that exists as a gas under conditions of 1 atmosphere, 23°C, and a relative humidity of 50% RH can be appropriately selected and used. Specific examples of the gas include, but are not limited to, nitrogen, oxygen, argon, carbon monoxide, carbon dioxide, neon, helium, krypton, and xenon.

[0054] In some embodiments, it is desirable that the gas does not contain a flammable gas as a main component, from the viewpoint of ease of handling of the intercellular structure 1. For example, more than 50%, more preferably 70% or more of the volume of the gas (referring to the volume under conditions of 1 atmosphere, 23°C, and a relative humidity of 50% RH; the same applies hereinafter unless otherwise specified) is preferably composed of one or more gases selected from the group consisting of nitrogen, argon, carbon dioxide, neon, helium, krypton, and xenon. An intercellular structure 1 configured in such a way that a gas containing an inert gas as a main component is sealed within the bag 10 has the advantage that, for example, if some cells abnormally generate heat and the bag 10 becomes sealed, the inert gas can be supplied from the bag 10 to the surrounding area.

[0055] In some embodiments, from the viewpoint of ease of sealing the gas (suppressing leakage), the volume of the Group 18 element (noble gas) in the volume of the gas is preferably 20% or less, more preferably 10% or less, even more preferably 5% or less, and may be 3% or less, 1% or less, or 0.5% or less.

[0056] Nitrogen and carbon dioxide are particularly preferred inert gases from the viewpoint of ease of handling and gas sealing of the intercellular structure 1. In some embodiments, the proportion of the total volume of nitrogen and carbon dioxide (which may be a gas having a composition containing only one of them) in the volume of the gas is preferably more than 50%, more preferably 70% or more, may be 80% or more, may be 90% or more, or may be 95% or more.

[0057] In some embodiments, the sealed space may contain a gas and a liquid as the fluid 20. By containing a liquid together with a gas in the sealed space, it is possible to adjust the compression characteristics (e.g., the value of compressive strain at a predetermined compressive stress) of the intercellular structure 1. The liquid may be, for example, water or an aqueous solution, but is not limited to these.

[0058] The amount of fluid 20 contained in the sealed space is not particularly limited, and can be adjusted as appropriate to exhibit appropriate properties (e.g., cushioning properties) according to the purpose, taking into consideration the type of fluid 20, the size of the sealed space, the manner of use of the inter-cell structure 1, etc.

[0059] Although not particularly limited, in some embodiments in which at least a gas is contained as the fluid 20 in the sealed space, the amount of the gas contained is determined by the surface area A [m ２ ] and the volume V [L] of the gas contained in the sealed space, the amount of gas G calculated by the following formula: G = V / (A / 2); is approximately 1.0 L / m ２ or more. This makes it easier to achieve cushioning that can change its thickness appropriately with good tracking in response to repeated cell expansion and contraction, etc. The reason why the surface area A in the denominator of the above formula is divided by 2 is to convert it into the area per side of the bag body 10. Note that, hereinafter, the value of A / 2 may be referred to as the surface area S per side of the bag body 10 that faces the sealed space.

[0060] The method for measuring the volume V of the gas can be selected from the well-known methods of underwater displacement, liquid phase displacement, and gas phase displacement. If the results differ depending on the measurement method, the method that gives the smallest value should be used. In the above formula, the value of the volume V of the gas is the volume at 1 atmosphere and 23°C.

[0061] In some embodiments, the gas volume G is 1.5 L / m ２ It is preferable that the amount of water used is 2.0 L / m or more. ２ More preferably, it is 5.0 L / m or more. ２ or more, and 7.0 L / m ２ or more, and 10 L / m ２ or more, and 15 L / m ２ or more, and 18 L / m ２ or more, and ２ Above, 22L / m ２ or more than 25 L / m ２ As the gas volume G increases, the amount of strain against pressure increases, and the buffering properties tend to improve. In addition, the gas volume G may be, for example, 100 L / m ２ In order to avoid an increase in the size of the inter-cell structure 1, in some embodiments, the ２ It is appropriate that the flow rate is 60 L / m or less. ２ Preferably, the flow rate is 45 L / m or less. ２ or less, and ２ or less, 30 L / m ２ or less than 25 L / m ２ It may be the following:

[0062] <Porous Sheet> A porous sheet 30 is contained in the sealed space within the bag 10 constituting the intercellular structure 1 together with the fluid 20. This configuration allows the repulsive force of the porous sheet 30 to be utilized as a mechanism for varying the thickness of the intercellular structure 1 in response to changes in compressive stress applied to the intercellular structure 1, in addition to the gas spring function exerted by the gas contained in the sealed space within the bag 10. For example, when the intercellular structure 1 is compressed under a predetermined applied pressure, the repulsive force of the porous sheet 30 can counteract at least a portion of the pressure. This suppresses an increase in the internal air pressure of the sealed space and reduces the load on the intercellular structure 1 (such as the load on the sealing end 10E) due to the increase in internal air pressure, thereby improving the durability of the bag 10. As a result, the gas spring function can be utilized to provide a durable buffer function with good compliance (e.g., low hysteresis loss). Furthermore, by suppressing the increase in internal air pressure, the difference in air pressure (differential pressure) between the inside and outside of the bag body 10 when the intercellular structure 1 is compressed with a predetermined applied pressure can be reduced compared to a configuration that does not utilize the repulsive force of the porous sheet 30. By reducing the differential pressure, for example, the gas in the sealed space can be better maintained (gas leakage can be suppressed) even when the intercellular structure 1 is used for a long period of time, and stable cushioning properties can be exhibited over a long period of time.

[0063] In addition, the porous sheet 30 is located away from the sealing edge 10E of the bag body 10. This configuration is advantageous in preventing damage and contamination of the porous sheet 30 during the manufacturing process of the intercellular structure 1, as will be described later.

[0064] As the porous sheet 30, for example, a porous sheet having a layer made of a fiber molded body containing fibers (hereinafter sometimes abbreviated as "fiber molded body") or a foam molded body containing a foam (hereinafter sometimes abbreviated as "foam molded body"). Here, "a layer made of a fiber molded body containing fibers" means a layer containing at least fibers as a constituent material, and "a layer made of a foam molded body containing a foam" means a layer containing at least foam as a constituent material. Fiber molded bodies, foam molded bodies, etc. will be described in detail below.

[0065] In some embodiments, the porous sheet 30 is a shaped body (fiber shaped body) containing fibers. The type of fiber contained in the fiber shaped body is not particularly limited, and may be inorganic fiber, organic fiber, or a combination of these. In some embodiments, non-limiting examples of materials that can be used for the fiber shaped body containing inorganic fibers include glass wool, long glass fiber, glass fiber mat, glass fiber needle mat, rock wool, alkaline earth silicate (AES) fiber, AES wool, etc. In other embodiments, non-limiting examples of materials that can be used for the fiber shaped body containing inorganic fibers include glass fiber, silica fiber, alumina fiber, silica-alumina fiber, silica-alumina-magnesia fiber, biosoluble inorganic fiber, glass fiber, zirconia fiber, alkaline earth metal silicate fiber, alkaline earth silicate (AES) fiber, glass wool, rock wool, basalt fiber, etc. Furthermore, non-limiting examples of materials that can be used for the fiber shaped body containing organic fibers include felts made of cellulose fiber, polyester, polypropylene, etc. The fiber molded product may contain one type of fiber or two or more types of fibers. The fiber assembly form is not particularly limited and may be, for example, a nonwoven fabric, a woven fabric, or a knitted fabric. In some embodiments, a fiber molded product in the form of a nonwoven fabric may be preferably used. The fibers used for the fiber molded product may be commercially available with a thermosetting resin dispersed therein as a binder (adhered to at least a portion of the fibers). Such fibers can be cut into the desired shape and then heated and compressed under appropriate conditions to form a fiber molded product.

[0066] In some embodiments, the fiber molded article used as the porous sheet 30 may be a sheet-like molded article containing inorganic fibers (an inorganic fiber-containing sheet). A suitable example of an inorganic fiber-containing sheet is glass wool. Glass wool generally contains fibers and a thermosetting resin (e.g., a phenolic binder), with the fibers bonded together by the thermosetting resin. It also has the effect of increasing compressive stress and providing a buffering function.

[0067] The inorganic fiber-containing sheet may contain inorganic particles as described below, or may not contain inorganic particles. In some embodiments of the intercellular structure 1 disclosed herein, the porous sheet 30 contained in the sealed space within the bag 10 preferably contains at least an inorganic fiber-containing sheet that does not contain inorganic particles (e.g., silica particles) (e.g., an inorganic fiber-containing sheet that does not contain inorganic particles and contains a binder).

[0068] The fiber content in the fiber molded product (e.g., inorganic fiber-containing sheet) is not particularly limited. In some embodiments, the fiber content in the fiber molded product is, for example, 50% by mass or more (typically 50% by mass to 99% by mass), preferably 60% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more (e.g., 82% by mass or more). In some embodiments, the fiber content may be 97% by mass or less, 95% by mass or less, or 93% by mass or less. When the fiber content is within the above range, the fiber molded product is more likely to exhibit cushioning properties.

[0069] The average fiber length of the fibers in the fibrous molded product (e.g., inorganic fiber-containing sheet) is not particularly limited. In some embodiments, the average fiber length of the fibers may be, for example, 1 mm to 200 mm, preferably 5 mm or more, more preferably 10 mm or more, even more preferably 20 mm or more, and preferably 175 mm or less, more preferably 150 mm or less, even more preferably 125 mm or less. When the average fiber length of the fibers is within the above range, the fibrous molded product is more likely to exhibit cushioning properties.

[0070] The average fiber diameter of the fibers of the fibrous molded product (e.g., inorganic fiber-containing sheet) is not particularly limited. In some embodiments, the average fiber diameter of the fibers may be, for example, 3 μm to 13 μm, preferably 4 μm or more, more preferably 4.5 μm or more, even more preferably 5 μm or more, and preferably 10 μm or less, more preferably 9 μm or less, even more preferably 8 μm or less. When the average fiber diameter of the fibers is within the above range, the fibrous molded product is likely to have both cushioning properties and low thermal conductivity.

[0071] In some embodiments, the fibrous molded article preferably contains a binder in addition to the fibers. The type of binder for the fibrous molded article is not particularly limited, but can be classified into organic binders and inorganic binders.

[0072] Specific examples of organic binders include thermoplastic resins, thermoplastic elastomers, thermosetting resins, thermosetting elastomers, sugars, and water-soluble polymers. Specific examples of inorganic binders include aluminum oxide, zirconium oxide, magnesium oxide, titanium oxide, and calcium oxide. When the binder is one of the above, shape stability is improved. The fiber molded product may contain one type of binder or two or more types of binders.

[0073] In embodiments in which the fiber molding contains a binder, the content of the binder is not particularly limited. In some embodiments, the content of the binder is, for example, 1% to 50% by mass of the fiber molding, preferably 2% by mass or more, more preferably 5% by mass or more, even more preferably 7% by mass or more, or may be 10% by mass or more or 12% by mass or more, and preferably 40% by mass or less, more preferably 30% by mass or less, even more preferably 20% by mass or less, or may be 18% by mass or less or 16% by mass or less. When the binder content is within the above range, good cushioning properties are likely to be exhibited.

[0074] In some embodiments, the fiber molded product used as the porous sheet 30 may be a sheet-like molded product containing inorganic particles and inorganic fibers (an inorganic particle / inorganic fiber-containing sheet). Examples of inorganic particles constituting the inorganic particle / inorganic fiber-containing sheet include those having the same material, shape, and / or properties as the inorganic particles that can be used in the thermal insulation layer described below. For example, an inorganic particle / inorganic fiber-containing sheet can be used as the porous sheet 30, in which the inorganic particles are primarily composed of at least one type of silica particles selected from the group consisting of dry silica, wet silica, and silica aerogel. The inorganic fibers constituting the inorganic particle / inorganic fiber-containing sheet may have the same material, shape, and / or properties as the inorganic fibers exemplified above as materials that can be used in the fiber molded product containing inorganic fibers, or may have the same material, shape, and / or properties as the inorganic particles that can be used in the thermal insulation layer described below. In some embodiments, an inorganic particle / inorganic fiber-containing sheet having the same configuration as the thermal insulation layer described below can be used as at least a portion of the porous sheet 30 contained in the sealed space within the bag 10. Such a configuration can also be recognized as an intercellular structure 1 having a configuration in which a heat insulating layer is disposed in the sealed space within the bag body 10. The intercellular structure 1 disclosed herein may have a configuration in which the porous sheet 30 housed in the sealed space within the bag body 10 includes both an inorganic fiber-containing sheet that does not contain inorganic particles and an inorganic particle / inorganic fiber-containing sheet.

[0075] In some embodiments, the porous sheet 30 is a molded article (foam molded article) containing a foam. The material of the foam is usually a resin such as a thermoplastic resin or a thermosetting resin. The foam can be molded by appropriately adopting a known molding method and its conditions.

[0076] The type of resin of the foam of the foam molded product is not particularly limited, and specific examples include foams formed from polyolefin resins such as polyethylene and polypropylene, polyethylene terephthalate resin, polyvinyl chloride resin (PVC), styrene resins such as polystyrene, polyurethane resins such as polyurethane resin, resol-type phenolic resins such as phenolic resin (PF), melamine resins such as melamine resin (MF), epoxy resins such as epoxy resin (EP), natural rubber (NR), styrene butadiene rubber (SBR), chloroprene rubber (CR), nitrile rubber (NBR), polyurethane, and the like.

[0077] The cell structure of the foamed molded product may be closed-cell or open-cell, and can be appropriately selected depending on the desired physical properties, etc. In some embodiments, a foamed molded product having an open-cell structure can be preferably used.

[0078] In the intercellular structure 1 disclosed herein, the number of porous sheets 30 accommodated in the sealed space within the bag 10 may be one or two or more. From the viewpoint of ease of manufacturing the intercellular structure 1 and thickness control, in some embodiments, the number of porous sheets 30 is suitably one to ten, preferably one to five, and more preferably one to three or one to two. For example, by combining a first porous sheet 30 having a relatively high compressive strength and / or weight per area with a second porous sheet 30 having a relatively low compressive strength and / or weight per area, the desired resilience and cushioning properties can be balanced while controlling the total thickness of the porous sheets 30. When two or more porous sheets 30 are used, the porous sheets 30 may be bonded (fixed) to each other or may not be bonded to each other. Bonding two or more porous sheets 30 to each other can be advantageous from the viewpoint of ease of manufacturing the bag. On the other hand, not bonding two or more porous sheets 30 to each other can be advantageous from the viewpoint of improving the cushioning properties of the intercellular structure 1.

[0079] The porous sheet 30 may be bonded to the inner surface of the bag body 10 by, for example, an adhesive or a pressure-sensitive adhesive, or may not be bonded by an adhesive or a pressure-sensitive adhesive, and is preferably not bonded by an adhesive or a pressure-sensitive adhesive. By not bonding by an adhesive or a pressure-sensitive adhesive, i.e., by not using an adhesive or a pressure-sensitive adhesive, an increase in thermal conductivity can be suppressed compared to when an adhesive or a pressure-sensitive adhesive is used.

[0080] The shape of the porous sheet 30 is not particularly limited. In some embodiments, the shape of the porous sheet 30 when viewed in plan may be, for example, a polygon such as a quadrangle, a circle, an ellipse, etc. Examples of quadrangles include rectangles (including squares and oblongs).

[0081] In the intercellular structure 1 disclosed herein, the weight of the porous sheet 30 accommodated in the sealed space within the bag body 10 (in a configuration having two or more porous sheets 30, the total weight of the porous sheets 30) W Ｂ is 150 g / m ２ This is because, when the porous sheet 30 is viewed from above, the area of ​​the porous sheet 30 is 1 m ２ This means that the weight per unit is 150g or more. Ｂ is 150 g / m ２ The porous sheet 30 described above can easily provide an appropriate repulsive force that can significantly contribute to improving the durability of the intercellular structure 1. From the viewpoint of easily obtaining a higher effect, in some embodiments, the weight W of the porous sheet 30 can be set to Ｂ is 250 g / m ２ Advantageously, it is equal to or greater than 200 g / m ２ It is preferable that the weight is 300 g / m or more. ２ More preferably, it is 350 g / m or more. ２ or more (for example, 360 g / m ２ or more), and ２ or more, and ２ or more, and ２ Above, 550g / m ２ Above, 600g / m ２ Above, 700g / m２ or more than 800 g / m ２ The weight W of the porous sheet 30 may be equal to or greater than 1000 mm. Ｂ is not particularly limited, for example, 20,000 g / m ２ or less, and ２ or less, and ２ or less, 2500 g / m ２ or less, 1500 g / m ２ It may be less than 1000 g / m ２ The weight W of the porous sheet 30 may be less than 10 ... Ｂ It is preferable that is not too large from the viewpoint of reducing the weight of the inter-cell structure 1, etc.

[0082] In some embodiments, the weight W of the porous sheet 30 contained in the sealed space in the bag body 10 (in a configuration having two or more porous sheets 30, the total weight of those porous sheets 30) Ｂ is 400 g / m from the viewpoint of facilitating reduction in the temperature dependency of the thickness. ２ It is appropriate that the weight is 450 g / m or more. ２ Advantageously, it is equal to or greater than 500 g / m ２ It is preferable that the weight is 550 g / m or more. ２ More preferably, it is 600 g / m or more. ２ More preferably, it is 650 g / m or more. ２ or more, and ２ or more, and ２ The weight W of the porous sheet 30 may be equal to or greater than 1000 mm. Ｂ is not particularly limited, for example, 20,000 g / m ２ or less, and ２ or less, and ２ or less, 2500 g / m ２ or less, 1500 g / m ２ It may be less than 1000 g / m ２ The weight W of the porous sheet 30 may be less than 10 ... Ｂ It is preferable that is not too large from the viewpoint of reducing the weight of the inter-cell structure 1, etc.

[0083] In the technology disclosed herein, the initial thickness of the porous sheet 30 (in a configuration having two or more porous sheets 30, the total thickness of those porous sheets 30) is not particularly limited and can be appropriately set so as to achieve the desired effect (such as the generation of a repulsive force against compression of the bag body) in the usage mode of the intercellular structure 1. The initial thickness of the porous sheet 30 may be, for example, 1 mm or more, 2 mm or more, 3 mm or more, or 4 mm or more. In some embodiments, the initial thickness of the porous sheet 30 is suitably 5 mm or more, preferably 7 mm or more, more preferably 8 mm or more, may be 10 mm or more, may be 12 mm or more, or may be 15 mm or more. Furthermore, in some embodiments, from the viewpoint of ease of manufacture of the intercellular structure 1, the initial thickness of the porous sheet 30 is suitably, for example, 100 mm or less, advantageously 75 mm or less, preferably 60 mm or less, may be 50 mm or less, may be 40 mm or less, may be 30 mm or less, 25 mm or less, or may be 20 mm or less.

[0084] As for the initial thickness of the porous sheet 30, similar to the heat insulating layer described below, the thickness of the cross section of the porous sheet 30 is measured using a thickness gauge (digital thickness gauge JAN-257, probe Φ20 mm, manufactured by Ozaki Manufacturing Co., Ltd.) when no pressure is applied (when no intentional load is applied to the porous sheet 30), and this measurement is further performed at any number of locations (for example, 10 locations), and the average value of the obtained values ​​can be used. In other words, the initial thickness of the porous sheet 30 means the thickness [mm] of the porous sheet 30 when no pressure is applied. Note that the initial thickness of the porous sheet 30 already contained in the sealed space within the bag body 10 can be estimated to be at least equal to or greater (typically, greater) than the thickness measured when the bag body 10 is disassembled and the porous sheet 30 is removed from the sealed space in a similar unpressurized state.

[0085] The thermal conductivity of the porous sheet 30 is not particularly limited. In some embodiments, the thermal conductivity of the porous sheet 30 at 80°C and 2 MPa is preferably 0.030 W / K·m or more, more preferably 0.040 W / K·m or more, even more preferably 0.050 W / K·m or more, and preferably 0.2 W / K·m or less, more preferably 0.15 W / K·m or less, and even more preferably 0.1 W / K·m or less. In some embodiments, the thermal conductivity of the porous sheet 30 at 600°C and 2 MPa is preferably 0.04 W / K·m or more, more preferably 0.05 W / K·m or more, even more preferably 0.06 W / K·m or more, and preferably 0.30 W / K·m or less, more preferably 0.25 W / K·m or less, and even more preferably 0.20 W / K·m or less. The thermal conductivity of the porous sheet 30 can be measured using a method similar to the method for measuring the thermal conductivity of a heat insulating layer described below.

[0086] There is no particular limitation on the thermal resistance of the porous sheet 30. In some embodiments, the thermal resistance of the porous sheet 30 under conditions of 80°C and 2 MPa is preferably 0.020 (K·m ２ ) / W or more, more preferably 0.025 (K m ２ ) / W or more, more preferably 0.03 (K m ２ ) / W or more, and preferably 0.07 (K m ２ ) / W or less, more preferably 0.06 (K m ２ ) / W or less, more preferably 0.05 (K·m ２ In some embodiments, the thermal resistance of the porous sheet 30 under conditions of 600°C and 2 MPa is preferably 0.001 (K·m ２ ) / W or more, more preferably 0.003 (K m ２ ) / W or more, more preferably 0.005 (K·m ２ ) / W or more, and preferably 0.1 (K m ２ ) / W or less, more preferably 0.05 (K·m ２ ) / W or less, more preferably 0.01 (K m ２) / W or less. The thermal resistance of the porous sheet 30 can be measured by the same method as the method for measuring the thermal conductivity of the heat insulating layer, which will be described later.

[0087] <Thermal Insulation Layer> The intercellular structure 1 disclosed herein may be configured to include a thermal insulation layer. The thermal insulation layer may be disposed inside the bag body 10 (for example, in a sealed space partitioned by the bag body 10) or outside the bag body 10.

[0088] The insulating layer is not particularly limited, and can be appropriately selected from those having a material and configuration suitable for insulating between cells of a lithium ion battery. In some embodiments, from the viewpoint of insulating performance, etc., an insulating layer containing inorganic particles can be preferably used. The type of inorganic particles is not particularly limited, and examples thereof include silica particles (silica), titanium oxide particles, zinc oxide particles, aluminum oxide particles, silicon carbide particles, ilmenite particles (ilmenite, FeTiO), zirconium silicate particles, iron (III) oxide particles, iron (II) (wustite (FeO) particles), magnetite particles (Fe ３ O ４ ), hematite particles (Fe ２ O ３)), chromium dioxide particles, zirconium oxide particles, manganese dioxide particles, zirconia sol, titania sol, silica sol, alumina sol, bentonite particles, kaolin particles, etc. Other examples of inorganic particles include carbon-based particles such as graphite, carbon black, and carbon. Graphite with a particle diameter of 18 μm or less is preferred. Graphite may be in any shape, including flake, scale, spherical, isotropic (artificial), and anisotropic (artificial). Examples of flake graphite include BF-3AK, FBF, and BF-10AK (manufactured by Chuetsu Graphite Industries Co., Ltd.), GE-1, Z-5F, CNP7, and V-10F (manufactured by Ito Graphite Industries Co., Ltd.), examples of scaly graphite include HLP and SB-1 (manufactured by Chuetsu Graphite Industries Co., Ltd.), examples of spherical graphite include SG-BH8 (manufactured by Ito Graphite Industries Co., Ltd.), examples of isotropic graphite (artificial) include AGB-5 (manufactured by Ito Graphite Industries Co., Ltd.), and examples of anisotropic graphite (artificial) include AG-6T (manufactured by Ito Graphite Industries Co., Ltd.). Examples of carbon black include TOKABLACK #5500 (manufactured by Tokai Carbon Co., Ltd.) and Mitsubishi Carbon Black MA100 (manufactured by Mitsubishi Chemical Corporation). The heat insulating layer may contain one type of inorganic particle, or may contain two or more types of inorganic particles. The inorganic particles are preferably inorganic particles that can suppress thermal radiation, more specifically, inorganic particles that have an absorption peak in the infrared region. The absorption peak in the infrared region can be measured using an infrared spectrophotometer. The inorganic particles may also function as a binder that binds inorganic fibers together.

[0089] The content of inorganic particles in the heat insulating layer is not particularly limited, and is, for example, 50% by mass to 99.5% by mass of the heat insulating layer, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and preferably 95% by mass or less, more preferably 90% by mass or less, even more preferably 85% by mass or less. When the content of inorganic particles is within the above range, good heat insulating properties and mechanical strength can be easily ensured.

[0090] The heat insulating layer contains silica (SiO ２) is preferably contained. Silica particles can be classified into crystalline silica, amorphous silica, etc. based on structural characteristics, and into natural silica, synthetic silica, etc. based on the method of acquisition. Synthetic silica can also be classified into dry silica, wet silica, silica aerogel, etc. based on the production method. Dry silica can be further classified into silica obtained by a combustion method, silica obtained by an arc method, etc., and wet silica can be classified into silica obtained by a gel method, silica obtained by a precipitation method, etc. The type of silica particles is not particularly limited, but dry silica and silica aerogel are preferred, and fumed silica, as a type of dry silica, is more preferred, and hydrophilic fumed silica is particularly preferred among fumed silica. The hydrophilic fumed silica refers to fumed silica having mainly hydrophilic silanol groups (Si—OH) on the surface, and generally refers to fumed silica in which the silanol groups have not been substituted with hydrophobic groups by surface treatment or the like. Silica particles generally exist as aggregates formed by aggregation of primary particles, or as aggregates formed by further aggregation of the aggregates. The silica particles in the heat insulating layer disclosed herein may be dispersed in the form of primary particles, aggregates, aggregates, or a combination thereof.

[0091] The average primary particle diameter of the silica particles is not particularly limited, and is, for example, 1 nm to 100 nm, preferably 2 nm or more, more preferably 4 nm or more, and preferably 80 nm or less, more preferably 40 nm or less, even more preferably 30 nm or less, and particularly preferably 20 nm or less. When the silica particles are fumed silica, the average primary particle diameter is, for example, 1 nm to 40 nm, preferably 2 nm or more, more preferably 4 nm or more, and preferably 30 nm or less, more preferably 20 nm or less, and even more preferably 18 nm or less. When the silica particles are silica aerogel, the average primary particle diameter is, for example, 1 nm to 20 nm, preferably 18 nm or less, and more preferably 10 nm or less. When the average primary particle diameter of the silica particles is within the above range, good thermal insulation properties are easily ensured. Methods for determining the average primary particle diameter of silica particles include measurements using an electron microscope such as a scanning electron microscope (SEM) or a transmission electron microscope (TEM). Specifically, a method can be used in which silica particles are randomly selected and their particle diameters are measured under an electron microscope, and the average value of the measured values ​​is calculated. The particle size may be the diameter if the particle is spherical, the intermediate value between the minor axis and the major axis if the particle is elliptical, or the intermediate value between the minor side and the major axis if the particle is an irregular particle.

[0092] The average particle size of the secondary aggregates of silica particles (aggregates of primary particles) is not particularly limited and is, for example, 0.1 μm to 100 μm, preferably 1 μm or more, more preferably 2 μm or more, and preferably 90 μm or less, more preferably 80 μm or less. Note that, as a method for determining the average particle size of the secondary aggregates of silica particles, a method of measuring using the same method as for the primary particle size can be mentioned.

[0093] The BET specific surface area of ​​the silica particles is, for example, 90 m ２ / g or more 380m ２ / g, preferably less than 130m ２ / g or more, more preferably 175m ２ / g or more, more preferably 200m ２ / g or more, preferably 350m ２ / g or less, more preferably 320m２ / g or less, more preferably 200m ２ / g or less. When the BET specific surface area of ​​the silica particles is within the above range, it becomes easier to ensure heat insulating properties even under high temperature and high humidity conditions. The BET specific surface area can be measured by a multipoint nitrogen adsorption method (BET method) in accordance with the International Organization for Standardization ISO 5794 / 1. For example, "AEROSIL 380" manufactured by Aerosil Co., Ltd. has a nominal value of the BET specific surface area of ​​380 m. ２ / g, and taking into account the error, it is 350m ２ / g~410m ２ In this case, the nominal value of 380 m ２ / g is considered as the standard.

[0094] The apparent specific gravity of the silica particles is not particularly limited and may be, for example, 30 g / L to 130 g / L, preferably 40 g / L or more, more preferably 50 g / L or more, and preferably 100 g / L or less, more preferably 80 g / L or less, and even more preferably 60 g / L or less. The apparent specific gravity of the silica particles can be determined by filling a container capable of measuring volume, such as a 250 mL graduated cylinder, measuring the filling mass (X g) and filling volume (Y mL) of the silica particles, and then dividing the filling mass by the filling volume ([apparent specific gravity (g / L)] = X / Y × 1000). When a nominal value of the apparent specific gravity is provided by a manufacturer or the like, that nominal value can be used.

[0095] Commercially available silica particles include hydrophilic fumed silica such as AEROSIL 50, 90, 130, 200, 200V, 300, and 380 from the AEROSIL series (manufactured by Nippon Aerosil Co., Ltd.), QS-09, QS-10, QS-102, QS-20, QS-20L, QS-30, Q40, and CP-102 from the Reolosil series (manufactured by Tokuyama Corporation), and HDKV15, N20, T30, and T40 from the HDK series (manufactured by Wacker Asahi Kasei Silicone Co., Ltd.), as well as hydrophobic fumed silica such as AEROSIL R972 and R976S from the AEROSIL series (manufactured by Nippon Aerosil Co., Ltd.), and HDK from the HDK series (manufactured by Wacker Asahi Kasei Silicone Co., Ltd.). Examples of suitable silica aerogels include AIRICA (manufactured by Tokuyama Corporation), which is a silica aerogel, such as H15, H20, and H30. The heat insulating layer may contain one type of silica particles or two or more types of silica particles.

[0096] The content of silica particles in the heat insulating layer is not particularly limited, and is, for example, 50% by mass or more (typically 50% by mass to 99.5% by mass), preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 85% by mass or less. When the content of silica particles is within the above range, good heat insulating properties and mechanical strength can be easily ensured.

[0097] The heat insulating layer may contain other components in addition to inorganic particles. In some embodiments, a heat insulating layer containing inorganic particles and inorganic fibers is preferred. The type of inorganic fiber is not particularly limited, but examples include silica fiber, glass fiber, alumina fiber, silica-alumina fiber, silica-alumina-magnesia fiber, biosoluble inorganic fiber, glass fiber, zirconia fiber, alkaline earth silicate fiber, alkaline earth silicate (AES) fiber, glass wool, rock wool, and basalt fiber. When the inorganic fiber is one of the above, heat resistance is improved. The heat insulating layer may contain one type of inorganic fiber, or may contain two or more types of inorganic fibers.

[0098] The content of inorganic fibers in the heat insulating layer is not particularly limited, and is, for example, 0.5% by mass to 50% by mass, preferably 1% by mass or more, more preferably 3% by mass or more, even more preferably 5% by mass or more, and preferably 40% by mass or less, more preferably 35% by mass or less, and even more preferably 30% by mass or less. When the fiber content is within the above range, it becomes easier to ensure good thermal resistance and to manufacture the heat insulating layer.

[0099] The average fiber length of the inorganic fibers contained in the heat insulating layer is not particularly limited and is, for example, 0.05 mm to 50 mm, preferably 0.5 mm or more, more preferably 1.0 mm or more, and even more preferably 2 mm or more, and is preferably 35 mm or less, more preferably 30 mm or less, more preferably 25 mm or less, more preferably 13 mm or less, and even more preferably 10 mm or less, and may be 8 mm or less, or may be 6 mm or less. When the average fiber length of the fibers is within the above range, the heat insulating layer is easy to produce.

[0100] The average fiber diameter of the inorganic fibers contained in the heat insulating layer is not particularly limited and is, for example, 0.1 μm to 50 μm, preferably 1 μm or more, more preferably 5 μm or more, even more preferably 7 μm or more, and preferably 25 μm or less, more preferably 20 μm or less, and even more preferably 15 μm or less. When the average fiber diameter of the fibers is within the above range, good heat insulating properties and mechanical strength can be easily ensured.

[0101] The heat insulating layer may contain organic fibers. Specific examples of organic fibers include felts made of cellulose fiber, polyester, polypropylene, etc. The content of the organic fibers in the heat insulating layer can be appropriately set so as to obtain the desired effect, and may be, for example, more than 0 parts by mass, 1 part by mass or more, 4 parts by mass or more, 8 parts by mass or more, or 16 parts by mass or more per 100 parts by mass of the inorganic fibers. On the other hand, in some embodiments, from the viewpoint of heat resistance, etc., the content of the organic fibers in the heat insulating layer is suitably less than 100 parts by mass, advantageously less than 50 parts by mass, or may be less than 20 parts by mass, less than 10 parts by mass, less than 5 parts by mass, or less than 1 part by mass, and may even be a heat insulating layer that does not contain organic fibers.

[0102] In addition to the inorganic particles, the heat insulating layer may contain a binder (binding agent) as one of the other components. The heat insulating layer may contain one type of binder, or may contain two or more types of binders. When the heat insulating layer contains a binder, shape stability tends to be improved.

[0103] When the heat insulating layer contains a binder, the type of binder is not particularly limited, but can be classified into organic binders and inorganic binders. Specific examples of organic binders include thermoplastic resins, thermoplastic elastomers, thermosetting resins, thermosetting elastomers, sugars, water-soluble polymers, etc. Specific examples of inorganic binders include aluminum oxide, zirconium oxide, magnesium oxide, titanium oxide, calcium oxide, etc. When the binder is one of the above, shape stability is effectively improved.

[0104] When the heat insulating layer contains a binder, the content of the binder is not particularly limited and is, for example, 0.01% by mass to 10% by mass of the heat insulating layer, preferably 0.05% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.2% by mass or more, and preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 1% by mass or less. When the binder content is within the above range, it becomes easier to achieve both heat insulating properties and shape stability.

[0105] The heat insulating layer is preferably a layer containing the above-mentioned inorganic particles, and more preferably a molded body formed from a mixture containing inorganic particles and inorganic fibers. When the molded body is a mixture containing inorganic particles and inorganic fibers, it is easier to achieve both heat insulating properties and mechanical strength. When the heat insulating layer is a molded body formed from a mixture containing inorganic particles and inorganic fibers, details of the mixing method of the inorganic particles, inorganic fibers, etc. will be described later.

[0106] The thickness of the insulating layer is not particularly limited and may be, for example, 0.5 mm to 10 mm, preferably 0.7 mm or more, and more preferably 0.8 mm or more or 0.9 mm or more. In some embodiments, the thickness of the insulating layer may be 1.0 mm or more, 1.5 mm or more, or 2 mm or more. The thickness of the insulating layer is preferably 7 mm or less, more preferably 5 mm or less, and even more preferably 3 mm or less. When the thickness of the insulating layer is within the above range, good thermal insulation properties are easily ensured and the size of the inter-cell structure 1 can be prevented from increasing. In some embodiments, the thickness of the insulating layer may be less than 2 mm, less than 1.5 mm, 1.3 mm or less, or 1 mm or less or less. By reducing the thickness of the insulating layer, the inter-cell structure 1 can be made thinner and lighter. The thickness of the insulating layer can be determined by measuring the cross section of the insulating layer at several points (e.g., 10 points) using a thickness measuring device (e.g., Ozaki Seisakusho's digital thickness gauge JAN-257 (measuring probe Φ20 mm)) when no pressure is applied (when no intentional load is applied to the insulating layer).

[0107] The density of the heat insulating layer is not particularly limited, and may be, for example, 0.2 to 0.5 g / cm ３ and preferably 0.3 g / cm ３ More preferably, 0.35 g / cm ３ More preferably, 0.37 g / cm ３ or more, and preferably 0.45 g / cm ３ The following is the result.

[0108] The thermal conductivity of the insulating layer at 80°C and 0.10 MPa pressure is preferably 0.010 W / K·m or more, and preferably 0.3 W / K·m or less, more preferably 0.1 W / K·m or less, more preferably 0.08 W / K·m or less, more preferably 0.06 W / K·m or less, more preferably 0.055 W / K·m or less, more preferably 0.045 W / K·m or less, and even more preferably 0.04 W / K·m or less.

[0109] The thermal conductivity of the insulating layer at 800°C and 0.10 MPa pressure is preferably 0.010 W / K·m or more, and preferably 0.3 W / K·m or less, more preferably 0.2 W / K·m or less, more preferably 0.1 W / K·m or less, more preferably 0.08 W / K·m or less, and even more preferably 0.075 W / K·m or less.

[0110] When the thickness (initial thickness) of the heat insulating layer is adjusted to 1 mm without pressure, the heat resistance at 80°C and 0.10 MPa pressure is preferably 0.010 (K·m ２ ) / W or more, more preferably 0.015 (K·m ２ ) / W or more, more preferably 0.020 (K·m ２ ) / W or more, more preferably 0.025 (K·m ２ ) / W or more, and preferably 0.1 (K m ２ ) / W or less.

[0111] The thermal resistance of the heat insulating layer having an initial thickness of 1 mm at 800°C and a pressure of 0.10 MPa is preferably 0.005 (K·m ２ ) / W or more, more preferably 0.010 (K·m ２ ) / W or more, more preferably 0.015 (K·m ２ ) / W or more, and preferably 0.1 (K m ２ ) / W or less.

[0112] The thermal conductivity of the heat insulating layer can be measured by the method described in Japanese Industrial Standard JIS A 1412-2:1999, "Methods for measuring thermal resistance and thermal conductivity of thermal insulating materials - Part 2: Heat flow meter method (HFM method)." The heat flow meter method (HFM method) is a secondary measurement method or comparative measurement method that measures heat transfer characteristics such as thermal conductivity and thermal resistance by comparing a flat plate of heat insulating material (heat insulating layer) as a test specimen with a standard plate. The detailed measurement procedure and measurement conditions are described below.

[0113] The insulation layer is cut to a predetermined size (e.g., 20 mm x 20 mm) to prepare a test specimen, and an alumina composite material ("RS-100", manufactured by ZIRCAR Refractory Composites, Inc., thickness: 5 mm, thermal conductivity: 0.66 W / K m) or the like is prepared as a standard plate. Next, the first thermocouple, titanium plate, insulation layer, titanium plate, second thermocouple, standard plate, and third thermocouple are placed on the lower plate of a pneumatic press in this order from top to bottom, and the test specimen, standard plate, thermocouple, etc. are tightly attached between the upper and lower plates. The upper and lower plates are then heated to their respective predetermined measurement temperatures, and a load is applied to the test specimen, etc. using the pneumatic press to achieve the predetermined measurement pressure.

[0114] The measurement temperatures may be set to 80° C. for the upper plate on the first thermocouple side and 30° C. for the lower plate on the third thermocouple side. On the other hand, the measurement temperatures under high temperature conditions may be set to 800° C. for the upper plate on the first thermocouple side and 80° C. for the lower plate on the third thermocouple side, for example.

[0115] The measurement pressure can be 0.10 MPa (load: 40 N). Measurement is continued under heating and pressure until the detected temperature of each thermocouple stabilizes, and the thermal conductivity k1 of the heat insulating layer can be calculated from the detected temperature of each thermocouple after the temperature stabilizes, the thickness of the heat insulating layer when pressurized, the thermal conductivity of the standard plate, and the thickness of the standard plate when pressurized, using the following formula (I): k1 = k2 × (L1 × ΔT1) / (L2 × ΔT2) ... (I) (In the formula, k1 is the thermal conductivity of the insulating layer [W / (m·K)], k2 is the thermal conductivity of the standard plate [W / (m·K)], L1 is the thickness of the insulating layer when pressed, L2 is the thickness of the standard plate, ΔT1 is the temperature difference between the temperatures of the second thermocouple and the third thermocouple, and ΔT2 is the temperature difference between the temperatures of the first thermocouple and the second thermocouple.) Note that the detected temperature being stable means that the temperature change after about 10 minutes is within a specified range (for example, within ±0.1°C).

[0116] The thermal resistance of the heat insulating layer can be calculated from the above-mentioned thermal conductivity k1 and thickness under pressure L1 by the following formula (II): R1 = L1 / k1 (II) (where R1 is the thermal resistance [(m ２·K) / W], k1 is the thermal conductivity of the heat insulating layer [W / (m ·K)], and L1 is the thickness of the heat insulating layer under pressure [m].

[0117] In some embodiments in which the intercellular structure 1 disclosed herein includes a thermal insulation layer, when a compression test is performed on the thermal insulation layer alone at a compression rate of 0.5 mm / min, the compressive strain value at a compressive stress value of 1.39 MPa (hereinafter also referred to as "1.39 MPa compression strain"; similar expressions apply) may be, for example, 45% or less or 40% or less. From the viewpoints of durability and suppression of powder generation, the compressive strain value is preferably 30% or less or 25% or less, advantageously 20% or less, and may be 18% or less, 15% or less, or 13% or less. The 1.39 MPa compression strain of the thermal insulation layer is greater than 0%, and may be, for example, 5% or more, 7% or more, 10% or more, 12% or more, or 15% or more. A thermal insulation layer having a 1.39 MPa compression strain within any of the above ranges can be used as a component of any of the intercellular structures 1 disclosed herein to easily realize an intercellular structure 1 with good thermal insulation and cushioning properties.

[0118] In some embodiments in which the intercellular structure 1 disclosed herein includes a thermal insulation layer, the strain at 1.00 MPa compression of the thermal insulation layer is, for example, suitably 40% or less, preferably 25% or less or 20% or less, advantageously 18% or less, and may be 15% or less, 12% or less, or 10% or less. The strain at 1.00 MPa compression of the thermal insulation layer is greater than 0%, and may be, for example, 4% or more, 6% or more, 8% or more, 10% or more, or 12% or more. A thermal insulation layer having a strain at 1.00 MPa compression within any of the above-mentioned ranges can be used as a component of any intercellular structure 1 disclosed herein to easily realize an intercellular structure 1 with good thermal insulation and cushioning properties.

[0119] In some embodiments in which the intercellular structure 1 disclosed herein includes an insulating layer, the insulating layer constituting the intercellular structure 1 suitably has a strain at 0.34 MPa compression of 30% or less, preferably 20% or less, and more preferably 15% or less. The strain at 0.34 MPa compression of the insulating layer is greater than 0%, and may be, for example, 3% or more, 5% or more, 7% or more, or 9% or more. An insulating layer having a strain at 0.34 MPa compression within any of the above ranges is likely to realize an intercellular structure 1 with good thermal insulation and cushioning properties (e.g., good compression characteristics in the loading-unloading test described below).

[0120] The number of heat insulating layers included in the intercellular structure 1 is usually 1 or more, and usually 10 or less, preferably 7 or less, and more preferably 5 or less. The technology disclosed herein can be preferably implemented in an embodiment in which the number of heat insulating layers is 3 or less or 2 or less (typically 1).

[0121] The insulating layer may be bonded to an adjacent layer (which may be a layer constituting the inner or outer surface of the bag material) with an adhesive or pressure-sensitive adhesive, or may not be bonded. In some embodiments, it is preferable that the insulating layer is not bonded with an adhesive or pressure-sensitive adhesive. By not using an adhesive or pressure-sensitive adhesive, the thermal conductivity can be reduced compared to when an adhesive or pressure-sensitive adhesive is used.

[0122] The shape of the heat insulating layer is not particularly limited. In some embodiments, the shape of the heat insulating layer when viewed from above may be, for example, a polygon such as a quadrangle, a circle, an ellipse, etc. Examples of quadrangles include rectangles (including squares and rectangles).

[0123] The method for producing the heat insulating layer is not particularly limited, and the layer can be produced by appropriately adopting known processes. For example, when the heat insulating layer is a layer formed from a mixture containing inorganic particles and inorganic fibers, the mixture can be prepared by adopting known mixing methods such as a wet method or a dry method. A method for producing a heat insulating layer including preparation of a mixture by a wet method can be a method including, for example, the following steps: Mixing step: a step of mixing inorganic particles and inorganic fibers in a solvent to obtain a mixed liquid; Coating step: a step of applying the mixed liquid obtained in the mixing step to obtain a coated film; Coating film forming step: a step of forming the coated film obtained in the coating step to obtain a heat insulating layer.

[0124] The mixing step is a step of mixing inorganic particles and inorganic fibers in a solvent to obtain a mixed liquid, specifically, a step of mixing inorganic particles and inorganic fibers in a solvent to prepare a mixed liquid (slurry state). The mixing in the mixing step can be performed using, for example, a Disper, a Labo Plastomill, a Trimix, a planetary mixer, a kneader, or the like.

[0125] The type of solvent is not particularly limited, and examples thereof include protic solvents such as alcohols, amides, and water, and aprotic solvents such as esters, ketones, nitriles, and ethers. The surface tension of the solvent is not particularly limited, and is, for example, 20 mN / m to 73 mN / m, preferably 21 mN / m or more, preferably 50 mN / m or less, more preferably 40 mN / m or less, and even more preferably 30 mN / m or less. When the surface tension of the solvent is within the above range, the heat insulating properties and mechanical strength are improved. The surface tension of the solvent can be measured by the ring method, for example.

[0126] The mixing temperature is not particularly limited, and is, for example, 20°C or higher and the boiling point of the solvent or lower, preferably 22°C or higher, and preferably 50°C or lower, more preferably 40°C or lower, and even more preferably 30°C or lower. When the mixing temperature is within the above range, the solvent (e.g., organic solvent) is less likely to volatilize, and the blending ratio is less likely to change. The mixing time is not particularly limited, and is, for example, 1 minute to 5 hours, preferably 5 minutes or longer, preferably 4 hours or shorter, more preferably 2 hours or shorter, and even more preferably 1 hour or shorter. When the mixing time is within the above range, the heat insulating layer can be easily produced efficiently.

[0127] The consistency (or penetrability) of the mixed liquid is not particularly limited, and is, for example, 50 to 200, preferably 55 or more, more preferably 60 or more, even more preferably 65 or more, and preferably 180 or less, more preferably 160 or less, and even more preferably 140 or less. When the consistency of the mixed liquid is within the above range, fiber breakage can be reduced when the fibers are uniformly dispersed. The consistency of the mixed liquid can be measured by the method described in Japanese Industrial Standards JIS K2220:2013 "Greases - Part 7: Penetration Test Method," and in particular, can be measured as "unmixed penetration." More specifically, the consistency of the mixed liquid can be measured by the method described in the Examples below.

[0128] The coating method and conditions in the coating step are not particularly limited, and any known method can be appropriately used. For example, coating can be performed using a comma coater, spin coater, die coater, dispenser, etc.

[0129] The molding method and molding conditions in the coating film molding step are not particularly limited, and known methods can be appropriately adopted. For example, compression molding can be performed using a heat press or a vacuum press, and drying can be performed using a floating oven, an IR oven, or the like. As drying conditions, a drying temperature of, for example, 60°C to 150°C is preferred. A drying time of, for example, 4 minutes to 20 minutes is preferred. The above molding method and molding conditions are determined based on the desired density (for example, a density of 0.2 to 0.5 g / cm). ３ The thickness of the insulating layer may be selected to provide a thermal barrier.

[0130] <Inter-cell structure> In the technology disclosed herein, the initial thickness (uncompressed thickness) of the inter-cell structure 1 is not particularly limited and can be appropriately set so as to achieve the desired effect (such as the generation of a repulsive force against compression) in the manner in which the inter-cell structure 1 is used. The initial thickness of the inter-cell structure 1 may be, for example, 1 mm or more, 2 mm or more, 3 mm or more, or 4 mm or more. In some embodiments, from the viewpoint of ease of manufacture of the inter-cell structure 1, the initial thickness of the inter-cell structure 1 is, for example, appropriately 100 mm or less, advantageously 75 mm or less, preferably 60 mm or less, and may be 50 mm or less, 40 mm or less, 30 mm or less, 25 mm or less, or 20 mm or less.

[0131] The inter-cell structure 1 disclosed herein may have a thickness measured under an applied pressure of 0.34 MPa (hereinafter also referred to as the "thickness at 0.34 MPa") within a range of, for example, approximately 1 mm to 50 mm. When the thickness of the inter-cell structure 1 is within the above range, the inter-cell structure 1 can appropriately buffer stress generated by battery expansion. From the viewpoint of easily achieving higher buffering properties, in some embodiments, the thickness of the inter-cell structure 1 at 0.34 MPa is preferably 1.5 mm or more, more preferably 1.7 mm or more, even more preferably 2 mm or more, and may be 3 mm or more, or may be 4 mm or more. Furthermore, in some embodiments, the thickness of the inter-cell structure 1 at 0.34 MPa is preferably 30 mm or less, more preferably 20 mm or less, even more preferably 15 mm or less, and may be 10 mm or less, 8 mm or less, 7 mm or less, 6 mm or less, or 5 mm or less.

[0132] Furthermore, the inter-cell structure 1 disclosed herein may have a thickness measured under an applied pressure of 3.45 MPa (hereinafter also referred to as the "thickness at 3.45 MPa") within a range of, for example, approximately 0.2 mm to 25 mm. When the thickness of the inter-cell structure 1 is within the above range, the inter-cell structure 1 can appropriately buffer stress generated by battery expansion. From the viewpoint of easily achieving higher buffering properties, in some embodiments, the thickness of the inter-cell structure 1 at 3.45 MPa is preferably 0.4 mm or more, more preferably 0.6 mm or more, even more preferably 0.8 mm or more, and may be 1 mm or more, or may be 2 mm or more. In some embodiments, the thickness of the inter-cell structure 1 at 3.45 MPa is preferably 20 mm or less, more preferably 15 mm or less, even more preferably 10 mm or less, and may be 8 mm or less, 6 mm or less, 5 mm or less, 4 mm or less, or 3 mm or less. For example, the inter-cell structure 1 preferably has a cushioning property such that the difference in thickness between applied pressures of 0.34 MPa and 3.45 MPa is 0.5 mm or more (more preferably 0.8 mm or more, even more preferably 1 mm or more, for example 1 mm). The difference in thickness is more preferably more than 1 mm, even more preferably 1.1 mm or more, and may be 1.2 mm or more, 1.3 mm or more, or 1.4 mm or more.

[0133] The thickness of the intercellular structure 1 when a pressure of 0.34 MPa is applied can be determined by sandwiching the intercellular structure 1 between two parallel metal plates having an area larger than the area S per side of the bag body 10 facing the sealed space formed inside the bag body 10 in the intercellular structure 1, performing zero point correction using a precision universal testing machine with the load on the two metal plates removed, applying a load at a compression rate of 0.5 mm / min, stopping the testing machine when the applied pressure calculated using the area S reaches 0.34 MPa, and measuring the cross-sectional thickness of the intercellular structure 1 or the bag body 10 at that time. As the precision universal testing machine, for example, an Autograph AGS-5kNX manufactured by Shimadzu Corporation or an equivalent can be used. The cross-sectional thickness of the bag body may be measured using the precision universal testing machine or a thickness measuring instrument such as a vernier caliper. The thickness of the intercellular structure 1 when a pressure of 3.45 MPa is applied is measured in the same manner as the thickness of the intercellular structure 1 when a pressure of 0.34 MPa is applied, except that the pressure applied during measurement is 3.45 MPa.

[0134] The thermal conductivity of the intercell structure 1 disclosed herein is not particularly limited. In some embodiments, the thermal conductivity of the intercell structure 1 under conditions of 800°C and 0.10 MPa pressure is preferably 0.04 W / K m or more, more preferably 0.05 W / K m or more, even more preferably 0.06 W / K m or more, and is preferably 200 W / K m or less, more preferably 100 W / K m or less, even more preferably 20 W / K m or less. The thermal conductivity of the intercell structure 1 can be measured in the same manner as the thermal conductivity of the heat insulating layer described above.

[0135] There is no particular limitation on the thermal resistance of the inter-cell structure 1 disclosed herein. The thermal resistance of the inter-cell structure 1 can be measured in the same manner as the thermal resistance of the heat insulating layer described above.

[0136] The intercellular structure 1, in which the bag 10 has a sealing edge 10E and a folded portion 10X, can be manufactured, for example, through the process shown in FIG. 5 . First, two laminated films 10′ for forming the bag 10 are stacked with a porous sheet 30 sandwiched between them (step (i)). Next, the opposing surfaces of the two laminated films 10′ are sealed in an annular shape at a location away from the porous sheet 30 (step (ii)). In this step, a fluid 20 is supplied between the laminated films 10′, and then the opposing surfaces of the two laminated films 10′ are sealed. The fluid 20 contains at least a gas such as air. This step results in a bag 10 containing the fluid 20 and the porous sheet 30. Next, the bag 10 is folded between the sealing edge 10E and the porous sheet 30 (step (iii)). For example, the bag 10 is folded over the entire periphery of the bag 10 between the sealing edge 10E and the porous sheet 30. For example, by going through the above steps, it is possible to manufacture the inter-cell structure 1 in which the bag body 10 has the sealing edge 10E and the folded portion 10X.

[0137] In the intercellular structure 1, as described above, the fluid 20 (including gas) is contained in the sealed space within the bag body 10, which allows the structure to function as a fluid 20 spring (gas spring) (realizing an elastic thickness variation mechanism), and in addition, the repulsive force of the porous sheet 30 within the sealed space can be utilized in the thickness variation mechanism. Such an intercellular structure 1 can vary in thickness with good follow-up in response to repeated expansion and contraction of the cells, thereby durably exhibiting a buffering function that relieves stress from the cells.

[0138] Furthermore, in the intercellular structure 1, the porous sheet 30 is positioned away from the sealing edge 10E within the bag 10. In the manufacturing process of such an intercellular structure 1, for example, when the porous sheet 30 is placed between the laminated films 10' for forming the bag 10 and the opposing surfaces of the laminated films 10' are sealed around the porous sheet 30 to form the sealing edge 10E (step (ii)), damage and contamination of the porous sheet 30 (which is away from the sealing edge 10E) can be prevented (forming a sealing edge at a location in the bag that contacts the porous sheet can cause damage and contamination of the porous sheet). Preventing damage and contamination of the porous sheet 30 helps to achieve good cushioning function in the intercellular structure 1 and ensure the durability of the cushioning function.

[0139] Additionally, in the intercell structure 1, the pouch 10 has a folded portion 10X, where the film portions 10a, 10b are folded back while overlapping, between the sealing edge 10E and the porous sheet 30. Such an intercell structure 1 can suppress an increase in the effective outer size of the pouch 10 while ensuring a sufficient dimension (seal width) for the sealing edge 10E to prevent leakage of the fluid 20 (including gas) from the pouch 10. The pouch 10 having the folded portion 10X helps to achieve a size appropriate for the battery cells (a size that is not too large compared to the battery cells) for the pouch 10 of the intercell structure 1 arranged in a battery module or battery pack. A configuration in which the bag body 10 has the folded portion 10X between the sealing edge 10E and the porous sheet 30 is suitable for ensuring a large area ratio of the porous sheet 30 to the outer size (effective outer size) of the bag body 10 after folding, compared to a configuration in which the bag body has the folded portion at the sealing edge (i.e., a configuration in which the bag body is folded at the sealing edge). In other words, it is useful for realizing a size of the bag body 10 of the manufactured inter-cell structure 1 that corresponds to the battery cells while allowing a porous sheet 30 with a larger size (area in a plan view) to be accommodated within the bag body 10 without contacting the sealing edge 10E during the manufacturing process. The larger the area ratio of the porous sheet 30 to the effective outer size of the bag body 10, the easier it is to achieve good cushioning function and improve the durability of that cushioning function.

[0140] As described above, the inter-cell structure 1 can be made to have a size suitable for a lithium-ion battery cell, while also being able to maintain a durable buffering function for mitigating stress from the cell.

[0141] Fig. 6 is a cross-sectional view schematically showing a folded portion 10X and its vicinity of an intercell structure 1 according to another embodiment. The intercell structure 1 shown in Fig. 6 is similar to the intercell structure 1 described above with reference to Figs. 1 and 2, except that it does not include a folded spacer 40 and includes a pressure-sensitive adhesive layer 51 as fixing means 50.

[0142] The adhesive layer 51 (fixing means 50) shown in Fig. 6 is a fixing means for fixing the sealing end 10E to the portion of the bag body 10 other than the folded portion 10X and the sealing end 10E. The adhesive layer 51 prevents the folded portion 10X from opening (deforming the film portions 10a, 10b in the direction returning from the folded shape to the flat shape). The adhesive layer 51 can be formed, for example, using a double-sided adhesive tape.

[0143] The intercellular structure 1 shown in FIG. 6 can be manufactured by performing the above-described step (iii) in the manufacturing process of the intercellular structure 1, for example, as follows. First, an adhesive layer 51 (fixing means 50) of a predetermined width and thickness is formed on the sealing edge 10E on one side of the bag body 10. The adhesive layer 51 may be formed using a single sheet of double-sided adhesive tape of a predetermined thickness, or may be formed by stacking two or more sheets of double-sided adhesive tape of a predetermined thickness. This formation method allows the adhesive layer 51 to be formed with high thickness accuracy. Next, for each side of the bag body 10 where the sealing edge 10E is formed, the bag body 10 is folded back along a location between the sealing edge 10E and the porous sheet 30 and a predetermined distance away from the porous sheet 30, with the adhesive layer 51 facing inward, and the sealing edge 10E is fixed to the portion inward of the folded location via the adhesive layer 51 (if the bag body 10 is rectangular in plan view and has sealing edges 10E formed on all four sides, the four sides of the bag body 10 are folded back to the same side). As a result, a folded portion 10X, where the two film portions 10a, 10b of the bag body 10 are folded back while overlapping, is formed between the sealing edge portion 10E and the porous sheet 30. By undergoing the above-described steps during the manufacturing process, for example, the inter-cell structure 1 shown in Fig. 6 can be manufactured. Having the folded portion 10X shown in Fig. 6 is advantageous from the perspective of miniaturizing the inter-cell structure 1 (reducing the size of the flat stopper).

[0144] 7 is a cross-sectional view schematically showing a folded portion 10X and its vicinity of an inter-cell structure 1 according to another embodiment. The inter-cell structure 1 shown in FIG. 7 is similar to the inter-cell structure 1 described above with reference to FIGS. 1 and 2, except that it does not include a folded spacer 40.

[0145] The intercellular structure 1 shown in FIG. 7 can be manufactured by performing the above-described step (iii) during the manufacturing process of the intercellular structure 1, for example, as follows. First, for each side of the bag body 10 where the sealing edge 10E is formed, a wire (not shown) is placed between the sealing edge 10E and the porous sheet 30 at a location a predetermined distance away from the porous sheet 30, and the bag body 10 is folded back to one side along the wire. (If the bag body 10 is rectangular in plan view and has sealing edges 10E formed on all four sides, the four sides of the bag body 10 are folded back to the same side.) This forms a folded back portion 10X, where the two film portions 10a, 10b of the bag body 10 are folded back while overlapping, between the sealing edge 10E and the porous sheet 30. The radius of curvature R of the folded back portion 10X can be adjusted by selecting the diameter of the wire. After folding back, the wire is pulled out of the folded back portion 10X. By performing the above-described steps during the manufacturing process, for example, the intercellular structure 1 shown in FIG. 7 can be manufactured. Not providing the folded spacers 40 is advantageous from the viewpoint of reducing the weight of the inter-cell structure 1 .

[0146] 8 is a cross-sectional view schematically showing a folded portion 10X and its vicinity of an intercell structure 1 according to another embodiment. The intercell structure 1 shown in FIG. 8 is similar to the intercell structure 1 described above with reference to FIGS. 1 and 2, except that it does not include a folded spacer 40 and includes a fixing tape 52 as fixing means 50.

[0147] The fixing tape 52 (fixing means 50) shown in FIG. 8 is a fixing means for fixing the sealing edge 10E to a portion (main region) of the bag body 10 other than the folded portion 10X and the sealing edge 10E. The fixing tape 52 prevents the folded portion 10X from opening (deforming the film portions 10a, 10b in a direction returning from a folded shape to a flat shape). A single-sided adhesive tape, for example, can be suitably used as the fixing tape 52. The fixing tape 52 as the fixing means 50 may have a length sufficient to fix the sealing edge 10E of the bag body 10 to the main region over the entire length of the sealing edge 10E, or may have a length sufficient to fix only a portion of the sealing edge 10E of the bag body 10 to the main region.

[0148] The intercellular structure 1 shown in Figure 8 can be manufactured by performing the above-mentioned step (iii) in the manufacturing process of the intercellular structure 1, for example, as follows. First, for each side of the bag body 10 where the sealing edge 10E is formed, a wire (not shown) is placed between the sealing edge 10E and the porous sheet 30 at a location a predetermined distance from the porous sheet 30, and the bag body 10 is folded back to one side along the wire (if the bag body 10 is rectangular in plan view and has sealing edges 10E formed on all four sides, the four sides of the bag body 10 are folded back to the same side). This forms a folded back portion 10X, where the two film portions 10a, 10b of the bag body 10 are folded back while overlapping, between the sealing edge 10E and the porous sheet 30. The above-mentioned radius of curvature R of the folded back portion 10X can be adjusted by selecting the diameter of the wire. After folding, the adhesive surface of the fixing tape 52 is adhered to the surface of the area (main area) of the bag body 10 where the film portion 10a and the film portion 10b are not joined and to the surface of the sealing edge 10E on the film portion 10b side, thereby fixing the sealing edge 10E to the main area of ​​the bag body 10. The wire is then pulled out of the folded portion 10X. By undergoing the above-described steps during the manufacturing process, for example, the intercellular structure 1 shown in FIG. 8 can be manufactured. Not providing the folded spacer 40 is advantageous from the perspective of reducing the weight of the intercellular structure 1. Furthermore, the fixing tape 52 adhered to the surface of the sealing edge 10E and the surface of the main area is advantageous for achieving strong fixation.

[0149] 9 is a cross-sectional view schematically showing a folded portion 10X and its vicinity of an inter-cell structure 1 according to another embodiment. The inter-cell structure 1 shown in FIG. 9 is similar to the inter-cell structure 1 described above with reference to FIGS. 1 and 2, except that it includes a folded spacer 40A instead of the folded spacer 40.

[0150] In this embodiment, the folded spacer 40A is made of a rod 42 and an adhesive layer 43. The adhesive layer 43 covers the entire or part of the circumferential surface of the rod 42 (FIG. 9 exemplarily shows a case where the adhesive layer 43 covers part of the circumferential surface of the rod 42). A wire, for example, can be suitably used as the rod 42. A double-sided adhesive tape, for example, can be suitably used as the adhesive layer 43. The radius of curvature R of the surface 10S of the folded portion 10X folded along the folded spacer 40A can be adjusted by selecting the thickness of the rod 42 and / or the thickness of the adhesive layer 43. From the viewpoint of suppressing the occurrence of cracks at and near the folded portion 10X of the bag body 10, the thickness of the folded spacer 40A is suitably 0.70 mm or more, advantageously 0.80 mm or more, preferably 0.90 mm or more (e.g., greater than 0.90 mm), more preferably 1.00 mm or more, and may be 1.06 mm or more, 1.10 mm or more, or 1.14 mm or more. Furthermore, in some embodiments, the thickness of the folded spacer 40A is preferably 2.00 mm or less, more preferably 1.80 mm or less, and may be 1.60 mm or less, 1.50 mm or less, or 1.40 mm or less. Having the folded spacer 40A not be too thick is advantageous for thinning the folded portion 10X and therefore helps to thin the inter-cell structure 1.

[0151] Since the folded spacer 40A has the adhesive layer 43 on at least a portion of the circumferential surface of the rod 42, in this embodiment, it also functions as a fixing means for fixing the folded portion 10X and / or the sealing end 10E to portions of the bag body 10 other than the folded portion 10X and the sealing end 10E. In other words, the folded spacer 40A is a folded spacer that also serves as a fixing means. Since the folded spacer 40A also serves as a fixing means, opening of the folded portion 10X (deformation of the film portions 10a, 10b in the direction of returning from the folded shape to the flat shape) is suppressed.

[0152] The intercellular structure 1 shown in FIG. 9 can be manufactured by performing the above-described step (iii) during the manufacturing process of the intercellular structure 1, for example, as follows. First, on each side of the bag 10 where the sealing edge 10E is formed, an adhesive layer 43 of a predetermined width and thickness is formed along a location between the sealing edge 10E and the porous sheet 30 and a predetermined distance away from the porous sheet 30. The adhesive layer 43 may be formed using a single piece of double-sided adhesive tape of a predetermined thickness, or may be formed by stacking two or more pieces of double-sided adhesive tape of a predetermined thickness. This formation method allows the adhesive layer 43 to be formed with high thickness accuracy. Next, a rod 42 is placed along approximately the center of the adhesive layer 43 in the width direction. Next, the bag 10 is folded to one side along the rod 42 on the adhesive layer 43 (if the bag 10 is rectangular in plan view and has sealing edges 10E on all four sides, the four sides of the bag 10 are folded to the same side). As a result, a folded portion 10X, where the two film portions 10a, 10b of the bag body 10 are folded back while overlapping, is formed between the sealing edge portion 10E and the porous sheet 30. By undergoing the above-described steps during the manufacturing process, for example, the intercellular structure 1 shown in Fig. 9 can be manufactured. Providing the folded spacer 40A including the rod 42 is advantageous for accurately adjusting the radius of curvature R of the surface 10S at the folded portion 10X.

[0153] The matters disclosed in this specification include the following: [1] An inter-cell structure disposed between adjacent cells of an arrayed battery module or battery pack including a plurality of lithium-ion battery cells, the inter-cell structure comprising: a bag body defining an enclosed space; and a porous sheet and a fluid including at least a gas within the enclosed space, the bag body being formed from a laminated film including a metal layer and a resin layer, the laminated film including a first film portion and a second film portion, the bag body having a sealing edge where the innermost layers of the first film portion and the second film portion are joined to each other to seal the enclosed space, the porous sheet being located away from the sealing edge of the bag body, and the bag body having a folded portion between the sealing edge and the porous sheet, where the first film portion and the second film portion overlap with each other and are folded back with the first film portion inside. [2] The inter-cell structure according to [1] above, wherein an outer surface of the first film portion at the folded back portion has a radius of curvature R of 0.30 mm or more. [3] The inter-cell structure according to [1] or [2] above, wherein the outer surface of the first film portion at the folded portion has a radius of curvature R that is equal to or less than half the uncompressed thickness of the inter-cell structure. [4] The inter-cell structure according to any of [1] to [3] above, further comprising a folded spacer, and the folded portion is folded back along the folded spacer. [5] The inter-cell structure according to [4] above, wherein the folded spacer also serves as a fixing means for fixing the folded portion and / or the sealing end to a portion of the bag other than the folded portion and the sealing end. [6] The inter-cell structure according to any of [1] to [5] above, further comprising a fixing means for fixing the folded portion and / or the sealing end to a portion of the bag other than the folded portion and the sealing end. [7] The inter-cell structure according to [6] above, wherein the fixing means includes a fixing tape that fixes the sealing end to a region of the bag where the first film portion and the second film portion are not joined. [8] The surface area A [m ２] and the amount of gas G calculated by the following formula based on the volume V [L] of the gas contained in the sealed space is 1.0 L / m ２

[0013] The intercellular structure according to any one of [1] to [7] above, wherein G=V / (A / 2). [9] The intercellular structure according to any one of [1] to [8] above, wherein the porous sheet comprises at least a sheet-like molded product containing inorganic fibers.

[10] The intercellular structure according to [9] above, wherein the sheet-like molded product containing inorganic fibers is a sheet-like molded product containing one or more selected from the group consisting of glass wool, long glass fibers, glass fiber mat, glass fiber needle mat, rock wool, alkaline earth silicate fibers, and alkaline earth silicate wool.

[11] The intercellular structure according to any one of [1] to

[10] above, wherein the porous sheet comprises a sheet-like molded product containing inorganic particles and inorganic fibers, and the inorganic particles comprise, as a main component, at least one type of silica particles selected from the group consisting of dry silica, wet silica, and silica aerogel.

[12] The intercellular structure according to any one of [1] to

[11] above, wherein more than 50% (by volume) of the gas is composed of one or more gases selected from the group consisting of nitrogen, argon, carbon dioxide, neon, helium, krypton, and xenon.

[0154] Hereinafter, several examples of the present invention will be described, but it is not intended that the present invention be limited to these specific examples.

[0155] <Materials Used> The intercellular structures according to the examples described below were fabricated using the following materials.

[0156] (Film) A: Laminated film (product of Resonac) with the configuration shown in Table 1. B: Laminated film (product of Nihon Matai) with the configuration shown in Table 1. Film produced by dry lamination method. The thickness of each layer and the total thickness of films A and B are the nominal values ​​of the manufacturer.

[0157]

[0158] (Porous sheet) Glass wool A: Glass wool manufactured by Paramount Glass Co., Ltd. (product name: Feather Glass FG, 24 kg / m ３ , thickness 25 mm) at 600 g / m ２ Glass wool B: Glass wool manufactured by Paramount Glass Industry Co., Ltd. (trade name: Feather Glass FG, 24 kg / m ３ , thickness 25 mm) at 360 g / m ２ The meat was sliced ​​to a size of 1 / 4.

[0159] Heat insulating layer: A mixed solvent (surface tension: 23 mN / m) of 300 parts by mass of isopropyl alcohol (IPA, surface tension: 21 mN / m) as a protic solvent and 60 parts by mass of water was mixed with 100 parts by mass of hydrophilic fumed silica particles ("AEROSIL (registered trademark) 200" manufactured by Nippon Aerosil Co., Ltd.), 20 parts by mass of glass fiber ("CS 6J-888" manufactured by Nitto Boseki Co., Ltd., average fiber diameter: 11 μm, average fiber length: 6 mm), and a non-polymeric dispersant, Kotamine 24P manufactured by Kao Corporation (active ingredient: dodecyltrimethylammonium chloride (C １２ H ２５ N ＋ (CH ３ ) ３ Cl), active ingredient content: 27% by mass), 1.9 parts by mass (0.5 parts by mass as active ingredient (ammonium salt)), and then 10 parts by mass of graphite ("SRN-5J", manufactured by Fuji Graphite Industries Co., Ltd., average particle size 5 μm) were added and mixed to a consistency of 70 to 140. The resulting mixture was applied to a substrate to a thickness of 4.0 mm to form a coating film. The coating film had a thickness of 2.0 mm and a density of 0.3 to 0.5 g / cm ３ The mixture was compression molded in a hot press into a sheet of 1.0 mm thick, and then dried at 100°C for 10 minutes to produce a porous sheet (a sheet-like molded article containing inorganic fibers and inorganic particles) as a heat insulating layer. The thickness of the resulting heat insulating layer was 1.0 mm, and the density was 0.37 g / cm. ３ The thermal conductivity of the heat insulating layer (800°C, 0.10 MPa) measured according to the method described below was 0.075 (W / m·K).

[0160] During the manufacturing process of the above-mentioned heat insulating layer, the consistency of the mixed liquid was measured as "immiscible consistency" in accordance with the contents of Japanese Industrial Standard JIS K 2220:2013 "Grease - Part 7: Consistency Test Method." Specifically, a container large enough that a conical weight would not come into contact with the mixed liquid when lowered was prepared, filled with the mixed liquid, and placed in a PENETRO METER manufactured by Nikka Engineering Co., Ltd., to which the weight was attached. Next, the position of the weight was adjusted to a position where the weight and the mixed liquid came into contact, and this position was designated as the zero point. Then, under room temperature (25°C) conditions, the weight was lowered for 5 seconds (±0.1 seconds), and the depth (mm) of the weight penetrating the mixed liquid x 10 was calculated as the consistency. The conical weight used was a standard cone as defined in the Japanese Industrial Standards, with a total mass of 102.5 g and a weight holder with a mass of 47.5±0.05 g.

[0161] The thermal conductivity of the thermal insulation layer was measured at 800°C and 0.10 MPa in accordance with the Japanese Industrial Standards (JIS) A 1412-2:1999, "Method for measuring thermal resistance and thermal conductivity of thermal insulation materials - Part 2: Heat flow meter method (HFM method)." First, the thermal insulation layer to be measured was cut into 20 mm x 20 mm pieces to prepare samples for thermal conductivity measurement. A sample, a reference sample (alumina composite material ("RS-100," manufactured by ZIRCAR Refractory Composites, Inc., thickness: 5 mm, thermal conductivity: 0.66 W / (m·K))), and a titanium plate (thickness: 0.2 mm) were prepared. Next, on the lower plate surface of a pneumatic press (manufactured by Imoto Machinery Co., Ltd.), from the top, thermocouple 1 (sheathed thermocouple K type (SCHS1-0), φ = 0.15, class JIS1, manufactured by Chino Corporation), titanium plate, heat insulating layer (sample) as a test specimen, titanium plate, thermocouple 2 (sheathed thermocouple K type (SCHS1-0), φ = 0.15, class JIS1, manufactured by Chino Corporation), standard plate, thermocouple 3 (sheathed thermocouple K type (SCHS1-0), φ = 0.15, class JIS1, manufactured by Chino Corporation) were sandwiched in this order to closely adhere the heat insulating layer, standard plate, thermocouple, etc. Next, the upper and lower plates were heated and the load of the press was adjusted to 40 N (equivalent to 0.10 MPa), and then pressurized. In the heated and pressurized state, measurement was continued until the detected temperature of the thermocouple stabilized. The heating temperatures were 800 ° C. for the upper plate and 80 ° C. for the lower plate. The temperature was defined as being stabilized when the temperature change after 10 minutes was within ±0.1°C. After the temperature was stabilized, the thermal conductivity k1 of the thermal insulating layer was calculated from the detected temperatures of each thermocouple, the thickness of the thermal insulating layer when compressed, and the thermal conductivity and thickness of the standard sample using the following formula (I): k1 = k2 × (L1 × ΔT1) / (L2 × ΔT2) ... (I) (where k1 is the thermal conductivity of the thermal insulating layer [W / (m K)], k2 is the thermal conductivity of the standard plate [W / (m K)], L1 is the thickness of the thermal insulating layer when compressed, L2 is the thickness of the standard plate, ΔT1 is the temperature difference between the temperatures of the second thermocouple (thermocouple 2) and the third thermocouple (thermocouple 3), and ΔT2 is the temperature difference between the temperatures of the first thermocouple (thermocouple 1) and the second thermocouple (thermocouple 2).)

[0162] The density of the heat insulating layer was calculated by cutting each heat insulating layer into a size of 20 mm x 20 mm, measuring the mass and thickness, and dividing the mass by the volume.

[0163] <Preparation of intercellular structure> (Example 1) Two sheets of film A were cut into rectangular shapes of 206 mm x 156 mm, and one sheet of porous sheet (glass wool A) was cut into a rectangular shape of 146 mm x 96 mm. Next, the porous sheet was sandwiched between the two sheets of film A and superimposed with the heat seal surface (CPP layer side) of film A facing inward (step (i)). At this time, the porous sheet was positioned at the center of film A (each side of film A was 30 mm outward from each side of the porous sheet).

[0164] Next, the heat-sealed surfaces of the two films A sandwiching the porous sheet were joined together at four sides to form a sealed edge (step (ii)). First, three sides of the two films A were heat-sealed while applying a load sufficient to compress the porous sheet (enough to enable heat sealing). The heat sealing was performed using a Fuji Impulse heat sealing machine, model "OPL-300-10," at 180°C for 4 seconds with a seal width of 10.0 mm for each side (0 mm to 10.0 mm inward from each side). After heat-sealing one side, the film was cooled to 45°C and then heat-sealed on the next side. Next, the load was released, allowing a predetermined amount of air to enter between the two films A, and the remaining side (the fourth side) of the film A was similarly heat-sealed with a seal width of 10.0 mm. In this way, the heat-sealed surfaces of the two films A sandwiching the porous sheet were joined together at four sides to form a sealed edge 20 mm away from the porous sheet and 10 mm wide, thereby obtaining a bag containing the porous sheet and air.

[0165] Next, a folded portion was formed around the porous sheet in the bag as follows (step (iii)). First, a 5.0 mm wide (0 mm to 5.0 mm inward from each side) and 0.50 mm thick adhesive layer (fixing means) was formed along each side of one side of the bag. This adhesive layer was formed by attaching a double-sided adhesive tape (product name "CS9862UA", manufactured by Nitto Denko Corporation, thickness: 0.50 mm). Next, for each side of the bag, the bag was folded back along a location 28 mm from the edge of the bag (a location 2 mm outward from the porous sheet, where the heat-sealed surfaces of the two film portions were not joined), with the adhesive layer facing inward, and the sealing end was fixed to the portion inward from the folded location via the adhesive layer. As a result, a folded portion in which the two film portions of the bag body are folded back while overlapping is formed between the sealing end and the porous sheet, and a bag body having outer dimensions of 150 mm x 100 mm (effective outer size) in plan view is obtained. The configuration of the folded portion and its vicinity in Example 1 corresponds to the configuration described above with reference to Figure 6. The positional relationship between the bag body and the porous sheet after folding in Example 1 is also schematically shown in Figure 10 (the folded portion is omitted in Figure 10 to simplify the drawing).

[0166] In this manner, an intercellular structure of Example 1 was obtained, in which air and glass wool A (porous sheet) were contained in a sealed space partitioned by a bag formed from two sheets of film A (bag material). In the obtained intercellular structure, a folded portion was formed between the sealing edge and the porous sheet in the bag, and the ratio of the size of the porous sheet (146 mm x 96 mm) to the effective outer size of the bag (150 mm x 100 mm) was 93% ( FIG. 10 ). In Table 2, the case where a folded portion was formed between the sealing edge and the porous sheet is indicated as "I" (in contrast, the case where a folded portion was formed within the width of the sealing edge is indicated as "II"). The radius of curvature R of the folded portion was calculated by subtracting four times the thickness of film A from the total thickness of the folded portion measured with a vernier caliper and dividing the result by 2. As an example, a Digimatic Caliper CD-15AX, a digital caliper manufactured by Mitutoyo Corporation, was used. The initial thickness of the obtained intercellular structure (unpressurized thickness measured under atmospheric pressure at 25°C) was 21.0 mm. The initial thickness was measured at the center of the intercellular structure using a digital thickness gauge J-B (measuring probe Φ50 mm, minimum scale 0.05 mm) manufactured by Ozaki Manufacturing Co., Ltd. The thickness of the seal layer at the sealing edge (calculated by subtracting twice the total thickness of the layers of film A other than the innermost layer from the total thickness of the sealing edge 10E measured with a dial thickness gauge H-1A manufactured by Ozaki Manufacturing Co., Ltd.) was approximately 156 μm on all four sides. The surface area (internal surface area) of the bag facing the sealed space was 150 mm × 100 mm × 2, and the volume of air contained in the sealed space (measured by the method described below) was 289.5 cm ３ From these values, the gas amount G of the inter-cell structure according to Example 1 was calculated as (289.5 × 10 －３ ) / (0.150 x 0.100 x 2 / 2) = 19.3 L / m ２ It is calculated as follows.

[0167] Comparative Example 1 The inter-cell structure of Comparative Example 1 was prepared in the same manner as in Example 1, except that two sheets of film A cut into a 166 mm x 116 mm rectangle were used, a porous sheet (glass wool A) cut into a 106 mm x 56 mm rectangle was used, the amount of air when heat-sealing the fourth edge was adjusted to the gas amount G shown in Table 2, and the method of forming the folded-back portions were the same. In this comparative example, the pressure-sensitive adhesive layer was not formed, and the bag was folded back to one side along each side of the bag at a location 8 mm away from the edge of the bag (2 mm from the inner edge of the location where the sealing edge was formed). This resulted in a folded-back portion within the width of the sealing edge, resulting in a bag with outer dimensions of 150 mm x 100 mm (effective outer size) in plan view. The relative positions of the bag and the porous sheet in Comparative Example 1 are shown in FIG. 11 (the folded-back portion is omitted in FIG. 11 for simplicity). In the intercellular structure of Comparative Example 1, the ratio of the size of the porous sheet (106 mm x 56 mm) to the effective outer size of the bag body (150 mm x 100 mm) was 40% (Fig. 11).

[0168] Example 2 The intercellular structure of Example 2 was produced in the same manner as Example 1, except that glass wool B was used instead of glass wool A, the amount of air when heat-sealing the fourth edge was adjusted to the gas amount G shown in Table 2, and the method of forming the folded-back portion was changed. In the method of forming the folded-back portion in this example, a pressure-sensitive adhesive layer having a width of 15.0 mm (ranging from 0 mm to 15.0 mm inward from each edge) and a thickness of 0.70 mm was first formed along each edge on one side of the bag. This pressure-sensitive adhesive layer was formed by overlapping two layers of double-sided pressure-sensitive adhesive tape (product name "CS9862UA", manufactured by Nitto Denko Corporation, thickness 0.35 mm). Next, the bag was folded back along each side of the bag, with the adhesive layer facing inward, along a location approximately 15 mm from the edge of the bag (a location approximately 15 mm outward from the porous sheet where the heat-sealed surfaces of the two film portions were not joined) (i.e., along the inner edge of the adhesive layer), and the sealing edge was fixed to a portion inward of the folded location via the adhesive layer. This formed a folded portion between the sealing edge and the porous sheet, where the two film portions of the bag were folded back while overlapping. In this example, the adhesive layer served as both a folded spacer and a fixing means. The thickness of the folded spacer and the radius of curvature R (mm) of the inner surface of the folded portion, calculated from the thickness of the folded spacer, are shown in Table 2. The configuration of the folded portion and its vicinity in Example 2 corresponded to the configuration described above with reference to Figure 2.

[0169] Examples 3 to 6 The inter-cell structures of each example were produced in the same manner as in Example 2, except that a porous sheet shown in Table 2 was used, the amount of air when heat-sealing the fourth edge was adjusted to the gas amount G shown in Table 2, and the thickness of the double-sided pressure-sensitive adhesive tape used to form the pressure-sensitive adhesive layer serving both as the folded spacer and the fixing means was as shown in Table 2.

[0170] (Reference Example 1) The intercellular structure of Reference Example 1 was produced in the same manner as in Example 2, except that a porous sheet was not used, the amount of air when heat-sealing the fourth edge was adjusted to the gas amount G shown in Table 2, and the method of forming the folded-back portion was changed. In the method of forming the folded-back portion in Reference Example 1, a wire with a diameter of 1.0 mm was placed on each side of the bag body at a location approximately 15 mm away from the edge of the bag body (a location approximately 15 mm away from the porous sheet and where the heat-sealed surfaces of the two film portions were not joined), and the bag body was folded back to one side along the wire (all four sides were folded back to the same side). This formed a folded-back portion between the sealing end and the porous sheet, where the two film portions of the bag body were folded back while overlapping. After folding back, the wire was pulled out of the folded-back portion. The configuration of the folded-back portion and its vicinity in Reference Example 1 corresponds to the configuration described above with reference to FIG. 7.

[0171] (Reference Example 2) An inter-cell structure of Reference Example 2 was produced in the same manner as Reference Example 1, except that after folding the bag body and before pulling the wire out of the folded portion, the sealing end was fixed to the part inward from the folded portion with a single-sided adhesive tape having a tape width of 15 mm (product name "No. 360UL", manufactured by Nitto Denko Corporation, thickness 0.06 mm). In this example, the single-sided adhesive tape had a length spanning the entire length of the sealing end on each side of the bag body. The configuration of the folded portion and its vicinity in Reference Example 2 corresponds to one aspect of the configuration described above with reference to Figure 8.

[0172] (Reference Example 3) The inter-cell structure of Reference Example 3 was produced in the same manner as Reference Example 1, except that the amount of air used when heat-sealing the fourth edge was adjusted to the amount of gas G shown in Table 2, and that after folding the bag body but before pulling the wire out of the folded portion, the sealing edge was fixed to the part inward from the folded portion with a single-sided adhesive tape (product name "No. 360UL", manufactured by Nitto Denko Corporation, thickness 0.06 mm) having a width of 15 mm and a length of 30 mm. In this example, the single-sided adhesive tape was attached to approximately the center of the sealing edge in the longitudinal direction on each side of the bag body. The configuration of the folded portion and its vicinity in Reference Example 3 corresponds to one embodiment of the configuration described above with reference to Figure 8.

[0173] Reference Example 4 The intercellular structure of Reference Example 4 was produced in the same manner as in Example 2, except that Film B was used as the laminated film, no porous sheet was used, the amount of air when heat-sealing the fourth edge was adjusted to the gas amount G shown in Table 2, and the method of forming the folded-back portion was changed. In the method of forming the folded-back portion in Reference Example 4, a pressure-sensitive adhesive layer having a width of 15.0 mm (7.5 mm to 22.5 mm inward from each edge) and a thickness of 0.14 mm was first formed parallel to each edge on one side of the bag. This pressure-sensitive adhesive layer was formed by attaching a double-sided pressure-sensitive adhesive tape (product name "VR5300", manufactured by Nitto Denko Corporation, thickness 0.14 mm). Next, a wire with a diameter of 0.8 mm was placed on each side of the bag at a location about 15 mm from the edge of the bag (a location about 15 mm away from the porous sheet and where the heat-sealed surfaces of the two film portions were not joined), and the bag was folded back to one side along the wire (all four sides were folded back to the same side). As a result, a folded back portion where the two film portions of the bag were folded back while overlapping was formed between the sealing end and the porous sheet. The configuration of the folded back portion and its vicinity in Reference Example 4 corresponds to the configuration described above with reference to Figure 9.

[0174] (Reference Example 5) The inter-cell structure of Reference Example 5 was produced in the same manner as Reference Example 4, except that Film A was used as the laminated film and the amount of air when heat-sealing the fourth side was adjusted to the gas amount G shown in Table 2.

[0175] (Reference Examples 6 and 7) The intercellular structures of Reference Examples 6 and 7 were produced in the same manner as Example 2, except that no porous sheet was used, the amount of air when heat-sealing the fourth edge was adjusted to the gas amount G shown in Table 2, and the thickness of the double-sided adhesive tape (product name "CS9862UA", manufactured by Nitto Denko Corporation) used to form the adhesive layer was 0.20 mm (Reference Example 6) or 0.25 mm (Reference Example 7).

[0176] (Reference Example 8) The inter-cell structure of Reference Example 8 was produced in the same manner as in Example 2, except that film B was used as the laminated film, a porous sheet was not used, the amount of air when heat-sealing the fourth edge was adjusted to the gas amount G shown in Table 2, and the thickness of the double-sided adhesive tape (product name "VR5300", manufactured by Nitto Denko Corporation) used to form the adhesive layer was 0.14 mm.

[0177] (Reference Example 9) The intercellular structure of Reference Example 9 was produced in the same manner as in Example 2, except that no porous sheet was used, the amount of air when heat-sealing the fourth side was adjusted to the gas amount G shown in Table 2, and the thickness of the double-sided adhesive tape (product name "VR5300", manufactured by Nitto Denko Corporation) used to form the adhesive layer was set to 0.14 mm.

[0178] <Measurement and Evaluation> (Measurement of the Volume V of Gas Contained in the Sealed Space of the Bag) The volume V of gas contained in the sealed space partitioned by the bag was measured by the underwater displacement method as follows. Specifically, pure water was placed in a cylindrical acrylic resin container with a bottom, an inner diameter of 50 mm, an outer diameter of 60 mm, and a depth of 80 mm. The container was then filled with pure water by placing a lid on the container, which had a diameter of 99.5 mm, a thickness of 10 mm, and a circular plate with a 2 mm diameter through-hole formed in the center and a 10 mm wide flange extending from the top end of the circular plate, to ensure that no air remained inside. The weight (W1) of the container containing pure water was measured to two decimal places. Next, the bag to be measured was placed in the container containing pure water in the same manner as above, and the lid with the through-hole was placed on top, filling the container with pure water, and the weight (W2) was measured. Furthermore, the volume (FV) of the bag material constituting the bag was calculated from the width x height x thickness x 2 sheets. Using these results, the volume V of the gas contained in the sealed space of the bag (volume at 1 atmosphere and 23°C) was calculated using the following formula. The results are shown in Table 2. Gas volume V = {(m Ｓ,Ｌ +m Ｓ,Ａ ) ÷ ρ Ｌ}-FV m Ｓ,Ｌ : Weight of container filled with pure water (W1) - Weight of container filled with pure water and containing bag (W2) m Ｓ,Ａρ: Weight of the bag measured by a weighing scale (i.e., the total weight of the bag material constituting the bag and the contents other than the gas contained in the bag, assuming that the weight of the gas can be ignored) Ｌ : Density of the liquid (water in this case) in the container

[0179] (Compression-Release Cycle Test) Using a hydraulic servo-type fatigue endurance tester (EHF UV50kN, manufactured by Shimadzu Corporation) under an environment of 25°C and 50% RH, the intercellular structures according to each example were compressed at a compression rate of 0.3 mm / sec until the compressive stress reached 3.45 MPa (zeroth compression), then released at a compression rate of 0.3 mm / sec until the compressive stress reached 0.34 MPa (first release), and then compressed at a compression rate of 0.3 mm / sec until the compressive stress reached 3.45 MPa (first compression). This compression-release operation between 3.45 MPa and 0.34 MPa constituted one cycle, and a compression-release cycle test was performed in which this cycle was repeated 3,650 times. After the test, the folded portions of the bag body of the intercellular structures were visually observed, and then a cross section cut in the thickness direction of the folded portions was observed using a field emission scanning electron microscope (FE-SEM) to determine whether cracks had occurred in the folded portions. The results are shown in Table 2. In Table 2, the case where no cracks were found in the folded portion is indicated as "A," the case where cracks were found only in part of the folded portion is indicated as "B," and the case where cracks were found over the entire surface of the folded portion is indicated as "C." The case where no cracks were found in the folded portion (A) is the case where no cracks were found by visual observation and no cracks were found by FE-SEM observation of 10 randomly selected cross sections (cross sections cut in the thickness direction) in the folded portion. The case where cracks were found only in part of the folded portion (B) is the case where cracks were found by visual observation only in part of the folded portion around the entire periphery of the bag body and also by FE-SEM observation of the cross section (cross section cut in the thickness direction) at the cracked location. Cases where cracks have occurred over the entire surface of the folded portion (C) refer to cases where cracks are confirmed by visual observation over the entire folded portion around the entire periphery of the bag body, and also by FE-SEM observation of cross sections (cut sections in the thickness direction) at 10 randomly selected locations on the folded portion. The FE-SEM observation was carried out as follows. Analytical device: A field emission scanning electron microscope, S-4800, manufactured by Hitachi, Ltd. was used. Measurement conditions: Backscattered electron images were observed at an accelerating voltage of 10 kV.Sample preparation: A sample cut out from the folded portion of the intercellular structure was embedded in acrylic resin, and then the embedded sample was mechanically polished and then ion-polished to form a cross section for observation, and then subjected to a conductive treatment.

[0180]

[0181] As shown in Table 2, in the intercellular structures of Examples 1 to 6 (having a folded portion between the sealing end and the porous sheet in the bag), a large area ratio for the porous sheet was ensured. In contrast, in the intercellular structure of Comparative Example 1 (having a folded portion within the width of the sealing end in the bag), a large area ratio for the porous sheet could not be ensured. Furthermore, in examples (Examples 1 to 6, Reference Examples 1 to 5) in which the radius of curvature R of the inner surface of the folded portion was 0.30 mm or more, the occurrence of cracks in the folded portion after the compression-release cycle test (3650 cycles) was suppressed compared to examples (Reference Examples 6 to 9) in which the radius of curvature R of the inner surface of the folded portion was less than 0.30 mm. In particular, in examples (Examples 1, 5, 6, Reference Examples 1 to 5) in which the radius of curvature R of the inner surface of the folded portion exceeded 0.45 mm, no cracks occurred in the folded portion even after the compression-release cycle test (3650 cycles).

[0182] Although specific examples of the present invention have been described above in detail, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and alterations of the specific examples exemplified above.

[0183] The inter-cell structure of the present invention can be applied to, for example, a battery module or a battery pack, and can be particularly suitably applied to a battery module or a battery pack including a secondary battery such as a lithium-ion secondary battery.

[0184] REFERENCE SIGNS LIST 1 inter-cell structure 10 bag body 10a film portion (first film portion) 10b film portion (second film portion) 10E sealing edge 10X folded portion 10S surface (outer surface) 20 fluid 30 porous sheet 40, 40A folded spacer 50 fixing means 80 battery module 81 lithium ion battery cell

Claims

1. An inter-cell structure disposed between adjacent cells of a battery module or battery pack including an array of multiple lithium-ion battery cells, the inter-cell structure comprising: a bag body defining an enclosed space; and a fluid including at least gas within the enclosed space; and a porous sheet, wherein the bag body is formed from a laminated film including a metal layer and a resin layer, the laminated film including a first film portion and a second film portion, and has a sealing edge where the innermost layers of the first film portion and the second film portion are joined to seal the enclosed space; the porous sheet is located away from the sealing edge of the bag body; and the bag body has a folded portion between the sealing edge and the porous sheet, where the first film portion and the second film portion overlap and are folded back with the first film portion on the inside.

2. The intercellular structure according to claim 1, wherein the outer surface of said first film portion at said folded portion has a radius of curvature R of 0.30 mm or more.

3. The intercellular structure according to claim 1, wherein the outer surface of said first film portion at said folded portion has a radius of curvature R of not more than half the uncompressed thickness of said intercellular structure.

4. The inter-cell structure according to claim 1, further comprising a fastening means for fastening the folded portion and / or the sealing end to a portion of the bag other than the folded portion and the sealing end.

5. The surface area A [m ２ ] and the amount of gas G calculated by the following formula based on the volume V [L] of the gas contained in the sealed space is 1.0 L / m ２ 2. The inter-cell structure according to claim 1, wherein G=V / (A / 2) or more.

6. The intercellular structure according to any one of claims 1 to 5, wherein the porous sheet comprises at least a sheet-like formed body containing inorganic fibers.

7. The intercellular structure according to claim 6, wherein the sheet-like molded product containing inorganic fibers is a sheet-like molded product containing one or more materials selected from the group consisting of glass wool, long glass fibers, glass fiber mat, glass fiber needle mat, rock wool, alkaline earth silicate fibers, and alkaline earth silicate wool.

8. The intercellular structure according to any one of claims 1 to 5, wherein the porous sheet comprises a sheet-like molded product containing inorganic particles and inorganic fibers, and the inorganic particles comprise, as a main component, at least one type of silica particles selected from the group consisting of dry silica, wet silica, and silica aerogel.

9. The intercellular structure of any one of claims 1 to 5, wherein greater than 50% (by volume) of the gas is composed of one or more gases selected from the group consisting of nitrogen, argon, carbon dioxide, neon, helium, krypton, and xenon.

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