Inter-cell structure

Abstract

Provided is an inter-cell structure for use in a battery module or a battery pack including an arrayed plurality of battery cells, said inter-cell structure being disposed between adjacent cells among the plurality of cells. This inter-cell structure includes a bag body having a bag material in which a laminated film including a metal layer and a resin layer is used as a constituent material, and a fluid contained in a sealed space partitioned by the bag material. The bag body has a seal part where the innermost layers of the laminated film are joined together to seal the sealed space, and the thickness of the seal layer in the seal part is greater than 100 μm and no greater than 600 μm. The fluid includes at least a gas. The inter-cell structure includes a porous sheet, and the weight of the porous sheet is 150 g / m2 or more.

Description

Inter-cell structure

[0001] The present invention relates to an inter-cell structure disposed between a plurality of arranged battery cells. This application claims priority to Japanese Patent Application No. 2024-078938 filed on May 14, 2024, and Japanese Patent Application No. 2024-156949 filed on September 10, 2024, the entire contents of which are incorporated herein by reference.

[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 a 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 Application 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, a 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 Stacked Separators on Electrode Reactions of Lithium Metal Anodes, 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 / Authors (January 2023)

[0007] As mentioned above, lithium-ion battery cells repeatedly expand due to charging and contract due to discharging, and also undergo irreversible expansion. Therefore, in a battery pack that integrates cells or a battery module that constitutes the battery pack (hereinafter collectively referred to as a "battery module, etc."), it is necessary to consider dimensional changes in the cell stacking direction, generated pressure, etc. 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 cells themselves (e.g., Patent Document 2, Non-Patent Document 3, Non-Patent Document 4). Even in a battery module, etc. that integrates battery cells other than lithium-ion battery cells, the gap between cells may accidentally or repeatedly change due to dimensional changes in the cell stacking direction, external forces, etc., and it is desirable to buffer such changes.

[0008] Therefore, an object of the present invention is to provide an intercell structure that is disposed between a plurality of arranged battery cells and can absorb fluctuations in the gap between adjacent cells with good adaptability and durability. One object of the present invention is to provide an intercell structure that is disposed between a plurality of arranged lithium ion battery cells and has a buffering property that can absorb fluctuations in thickness with good adaptability and durability due to repeated expansion and contraction of the cells.

[0009] This specification provides an inter-cell structure that is disposed between adjacent cells in a battery module or battery pack including a plurality of arranged battery cells. The inter-cell structure includes a bag body having a bag material made of a laminated film including a metal layer and a resin layer as a constituent material, and a fluid contained in an enclosed space partitioned by the bag material. The bag body has a seal portion where the innermost layers of the laminated film are joined to seal the enclosed space, and the thickness of the seal layer in the seal portion is greater than 100 μm and less than or equal to 600 μm. The fluid includes at least a gas. The inter-cell structure also includes a porous sheet, and the weight of the porous sheet is 150 g / m. ２ The inter-cell structure having such a configuration can buffer variations in the gap between adjacent cells with good compliance and durability. The battery cells can be, for example, cells of a non-aqueous electrolyte secondary battery, such as a lithium-ion battery cell.

[0010] In some preferred embodiments, the battery cells are lithium-ion battery cells. Therefore, 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 having a pouch material made of a laminated film including a metal layer and a resin layer, and a fluid contained in a sealed space partitioned by the pouch material. The pouch has a seal portion where the innermost layers of the laminated film are joined to seal the sealed space, and the thickness of the seal layer in the seal portion is greater than 100 μm and less than 600 μm. The fluid includes at least a gas. The inter-cell structure also includes a porous sheet, and the weight of the porous sheet is 150 g / m. ２ The intercellular structure having such a configuration can exhibit excellent shock-absorbing properties, such as being able to change its thickness appropriately with good follow-up properties in response to repeated expansion and contraction of the cells, with good durability.

[0011] In some embodiments, the porous sheet is contained in the sealed space. In such an embodiment, the inter-cell structure has an inner thickness TA of the bag body when a pressure of 0.34 MPa is applied. IN (0.34) [mm] and the thickness TB of the porous sheet when not pressed NP The relationship between [mm] and TB is as follows: NP >TA IN It is preferable that the relationship satisfies (0.34). With an inter-cell structure configured to satisfy the above relationship, the porous sheet is accommodated together with gas in the sealed space of the bag, and thus the durability-enhancing effect can be suitably exhibited.

[0012] In some embodiments, the bag body has a 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 ２This makes it easier to achieve a cushioning effect that allows the thickness to change with good follow-up in response to variations in the gap between the cells (for example, variations in the gap between the cells due to repeated expansion and contraction of the cells).

[0013] The porous sheet may be, for example, a sheet-like molded article containing inorganic fibers, a foam sheet, or a combination thereof. Some preferred intercellular structures include at least a sheet-like molded article containing inorganic fibers (hereinafter also referred to as an inorganic fiber-containing sheet) as the porous sheet. For example, a configuration in which an inorganic fiber-containing sheet is housed together with gas in an enclosed space partitioned by the bag material can effectively improve the durability of the buffer function. Examples of preferred inorganic fiber-containing sheets include sheet-like molded articles containing one or more materials selected from the group consisting of glass wool, long glass fibers, glass fiber mats, needle glass fiber mats, rock wool, alkaline earth silicate (AES) fibers, and AES wool. Some other preferred intercellular structures include at least a foam sheet as the porous sheet. Examples of preferred foam sheets include foam sheets formed from one or more of polyolefin resins, polyurethane resins, silicone resins, and rubbers such as natural rubber and synthetic rubber. According to an intercellular structure in which such a foam sheet is arranged on the outside of a bag material, for example, the durability of the cushioning function can be effectively improved.

[0014] In some embodiments, the porous sheet 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 not containing inorganic particles may be used in combination.

[0015] 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.

[0016] 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.

[0017] 1 is a perspective view schematically illustrating an example of a battery module in which an inter-cell structure according to an embodiment is disposed between adjacent battery cells, and FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1. FIG. 3 is a cross-sectional view schematically illustrating an inter-cell structure according to an embodiment.

[0018] 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.

[0019] 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.

[0020] 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."

[0021] The intercellular structure disclosed in this specification includes a bag body having a bag material, a fluid contained in a sealed space defined by the bag material, and a porous sheet. The fluid includes at least a gas.

[0022] <Bag Material> The bag material used to form the bag body is a laminate film containing a metal layer and a resin layer. A laminate film with such a configuration can easily form a bag body that combines the gas barrier properties provided by the metal layer and the ease of deformation (cushioning properties) and formability provided by the resin layer.

[0023] 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.

[0024] 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, or may be 10 μm or more, 20 μm or more, or may be 30 μm or more. In some embodiments, from the viewpoint of suppressing heat conduction through the bag, the thickness of the metal layer is suitably 100 μm or less, advantageously 80 μm or less, preferably 60 μm or less, or may be 50 μm or less, 40 μm or less, 30 μm or less, or 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 measuring device (e.g., a dial thickness gauge H-1A (measuring probe Φ5 mm) manufactured by Ozaki Manufacturing Co., Ltd.). If the nominal value of the thickness of the metal layer of the bag material is provided by the manufacturer or the like, that nominal value may be used.

[0025] 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.

[0026] 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. Furthermore, 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 determined by averaging values ​​measured at several locations (e.g., 10 locations) using a thickness measuring device (e.g., a dial thickness gauge H-1A (5 mm diameter probe) manufactured by Ozaki Manufacturing Co., Ltd.). If the nominal value of the thickness of the resin layer of the bag material is provided by the manufacturer, that nominal value may be used.

[0027] 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, it is preferable that at least the innermost layer is a resin layer. The bag has a seal portion where the innermost layers are joined together to seal the sealed space. In some preferred embodiments, the innermost layer may be a heat-seal layer that is welded when forming the bag from the laminate film (bag material). 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 second resin layer (which may be the innermost layer of the laminate film) 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 viewpoint of ease of heat sealing and strength, preferred resin layers include a CPP layer and an LLDPE layer. In addition, examples of resin layers that are preferred from the viewpoint of low gas permeability include an EVOH layer and a PVDC layer. The materials of the innermost layers joined at the seal portion may be the same or different. The use of the same material for the innermost layers can be advantageous from the viewpoint of heat sealability.

[0028] The thickness of the innermost layer of the laminate film may be, for example, 40 μm or more. In some embodiments, from the viewpoint of the strength and durability of the sealed portion 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 laminate 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. Not having an excessively large thickness of the innermost layer is advantageous from the viewpoint of reducing the thickness of the sealing layer at the sealed portion 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.

[0029] In some embodiments, a laminate film having a structure in which a first resin layer, a metal layer, and a second resin layer are laminated in this order from the outside of the bag body can be preferably used. The first resin layer can be a layer that constitutes the outer surface of the bag body formed using the laminate film (bag material). The first resin layer can be useful for imparting surface insulation and antifouling properties to the bag body and protecting the metal layer from deterioration and damage. Non-limiting preferred examples of the first resin layer include a nylon layer (e.g., an ONY layer) and a PET layer. The metal layer can be, for example, an aluminum layer, although not particularly limited thereto. The second resin layer can be the innermost layer of the laminate film.

[0030] 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).

[0031] In some embodiments, the laminate film used as the bag material 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 associated with fluctuations in the gap between cells (e.g., fluctuations in the gap between cells due to repeated cell expansion and contraction). For example, the Young's modulus of the bag material 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 the formability and cushioning properties of the bag body, the Young's modulus of the bag material (which may be a 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 tensile speed during measurement is appropriately set depending on the material and structure of the bag material, the size of the measurement sample, etc., and can be set to, for example, 5 mm / min. If a nominal value of Young's modulus is provided by the manufacturer, etc., this nominal value may be used.

[0032] Furthermore, from the viewpoint of the strength and durability of the bag body, the tensile strength of the bag material 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 may be 70 N / 10 mm or more. The upper limit of the tensile strength of the bag material is not particularly limited. In some embodiments, from the viewpoint of the formability and cushioning properties of the bag body, the tensile strength of the bag material may be, for example, 300 N / 10 mm or less, 200 N / 10 mm or less, or even 100 N / 10 mm or less. Tensile strength is determined by measuring in an environment of 25°C and 50% RH in accordance with JIS K 7127 or JIS C 2318-72. The pulling speed during measurement is appropriately set depending on the material and structure of the bag material, the size of the measurement sample, etc., and can be, for example, 5 mm / min. If a nominal value of tensile strength is provided by a manufacturer, etc., that nominal value may be used.

[0033] The thickness of the bag material 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 bag material 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 bag material 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 bag material is within the above range, it is easy to appropriately achieve both deformability (shock-absorbing properties) that can easily absorb fluctuations in the gap between cells (e.g., fluctuations in the gap between cells due to thickness fluctuations accompanying expansion and contraction between cells) and the mechanical strength of the bag body. The thickness of the bag material can be the average value of measurements taken at several locations (for example, 10 locations) using a thickness measuring device (for example, a dial thickness gauge H-1A (measuring probe Φ5 mm) manufactured by Ozaki Manufacturing Co., Ltd.). If the nominal value of the thickness of the bag material is provided by the manufacturer, etc., that nominal value may be used.

[0034] <Fluid> The bag constituting the intercellular structure disclosed herein has a sealed space partitioned by the bag material. A fluid is contained in the sealed space. Here, the fluid includes at least a gas. That is, at least a gas is contained in the sealed space. By containing a gas in the sealed space of the bag, the bag can function as a gas spring, making it easier to realize an intercellular structure that exhibits high followability to fluctuations in the gap between cells (e.g., fluctuations in the gap between cells due to repeated expansion and contraction of cells). Here, "containing at least a gas" as the fluid means that the fluid 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 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.

[0035] Here, "sealed" means that leakage of the fluid contained in the sealed space to the outside of the bag is sufficiently restricted for practical purposes. For example, in a configuration in which the fluid contains a gas, in a sealability test in which the bag 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.

[0036] 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.

[0037] 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 the bag, etc. For example, it is preferable that 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) be composed of one or more gases selected from the group consisting of nitrogen, argon, carbon dioxide, neon, helium, krypton, and xenon. An inter-cell structure in which a gas containing an inert gas as a main component is sealed within a bag has the advantage that, for example, if some cells generate abnormal heat and the bag seal is broken, the inert gas can be supplied to the surroundings from the bag.

[0038] 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.

[0039] In view of the ease of handling the bag and the ease of sealing the gas, particularly preferred inert gases include nitrogen and carbon dioxide. In some embodiments, the proportion of the total volume of the gas, which is the total volume of nitrogen and carbon dioxide (which may be a gas containing only one of them), is preferably more than 50%, more preferably 70% or more, and may be 80% or more, 90% or more, or even 95% or more.

[0040] In some embodiments, the sealed space may contain a gas and a liquid as the fluid. By containing a liquid together with a gas in the sealed space, it is possible to adjust the compressive properties (e.g., the value of compressive strain at a predetermined compressive stress) of the bag body and the intercellular structure including the bag body. The liquid may be, for example, water or an aqueous solution, but is not limited to these.

[0041] The amount of fluid contained in the sealed space is not particularly limited, and can be adjusted as appropriate, taking into consideration the type of fluid, the size of the sealed space, the manner of use of the inter-cell structure, etc., so as to exhibit appropriate properties (e.g., cushioning properties) according to the purpose.

[0042] Although not particularly limited, in some embodiments in which at least a gas is contained as the fluid 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 properties that allow the thickness to change with good follow-up in response to variations in the gap between cells (for example, variations in the gap between cells due to repeated expansion and contraction of the cells). 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. Note that, hereinafter, the value of A / 2 may be referred to as the surface area S per side of the bag material facing the sealed space.

[0043] 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.

[0044] 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 ２As 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 increasing the size of the inter-cell structure, 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, 35 L / m ２ or less, 30 L / m ２ or less than 25 L / m ２ It may be the following:

[0045] <Porous Sheet> The intercellular structure disclosed herein includes a porous sheet. This configuration allows the repulsive force of the porous sheet to be utilized in addition to the gas spring function exerted by the gas contained in the sealed space of the bag as a mechanism for varying the thickness of the intercellular structure in response to changes in compressive stress applied to the intercellular structure. For example, when the intercellular structure is compressed with a predetermined applied pressure, the repulsive force of the porous sheet can counteract at least a portion of the pressure. This suppresses an increase in internal air pressure in the sealed space, reducing the load on the bag (e.g., load on the seal portion) due to the increase in internal air pressure, thereby improving the durability of the bag and the intercellular structure including the bag. As a result, the buffer function with good compliance (e.g., low hysteresis loss) can be durablely exerted by utilizing the gas spring function. Furthermore, by suppressing the increase in internal air pressure, the air pressure difference (pressure difference) between the inside and outside of the bag when the intercellular structure is compressed with a predetermined applied pressure can be reduced compared to a configuration in which the repulsive force of the porous sheet cannot be utilized. The reduction in the pressure difference allows the gas in the sealed space of the bag to be better retained (gas leakage suppressed) even during long-term use of the intercellular structure, thereby enabling stable cushioning properties to be exhibited over a long period of time. The porous sheet may be housed within the sealed space of the bag, may be disposed outside the bag, or may be disposed both within and outside the sealed space of the bag.

[0046] In some embodiments of the intercellular structure disclosed herein, the porous sheet is contained in a sealed space of a bag body. This configuration allows the repulsive force of the porous sheet to be utilized in addition to the gas spring function exerted by the gas contained in the sealed space of the bag body as a mechanism for varying the thickness of the bag body in response to changes in compressive stress applied to the bag body. For example, when the bag body is compressed with a predetermined applied pressure, the repulsive force of the porous sheet can counteract at least a portion of the pressure. This suppresses an increase in internal air pressure in the sealed space, reducing the load on the bag body (e.g., load on the seal portion) due to the increase in internal air pressure, thereby improving the durability of the bag body. As a result, the buffer function with good compliance (e.g., low hysteresis loss) can be exhibited with good durability by utilizing the gas spring function. Furthermore, by suppressing the increase in internal air pressure, the air pressure difference (pressure difference) between the inside and outside of the bag body when the bag body is compressed with a predetermined applied pressure can be reduced compared to a configuration in which the repulsive force of the porous sheet cannot be utilized. By reducing the pressure difference, the gas in the sealed space of the bag body can be better retained (gas leakage can be suppressed) even when the inter-cell structure is used for a long period of time, and stable cushioning properties can be achieved over a long period of time.

[0047] As the porous sheet, 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") can be preferably used. 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.

[0048] In some embodiments, the porous sheet is a shaped article (fiber shaped article) containing fibers. The type of fiber contained in the fiber shaped article 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 article 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 article 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 article 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.

[0049] In some embodiments, the fiber molded article used as the porous sheet 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.

[0050] 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 disclosed herein, the porous sheet accommodated in the sealed space of the bag 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).

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] In some embodiments, the fiber molded article used as the porous sheet may be a sheet-like molded article 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, 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 article 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 a configuration similar to the thermal insulation layer described below can be used as at least a portion of the porous sheet contained in the sealed space of a bag. This configuration can also be recognized as an intercellular structure in which a thermal insulation layer is disposed in the sealed space of a bag. The intercellular structure disclosed herein may be configured to include both an inorganic fiber-containing sheet that does not contain inorganic particles and an inorganic particle / inorganic fiber-containing sheet as the porous sheet contained in the sealed space of the bag.

[0058] In some embodiments, the porous sheet is a molded article (foamed 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.

[0059] The type of resin constituting the foam molded body (e.g., foam sheet) is not particularly limited. Specific examples include foams formed from resins such as polyolefin resins such as polyethylene and polypropylene, polyester resins such as polyethylene terephthalate resin, styrene resins such as polyvinyl chloride resin (PVC) and polystyrene, polyurethane resins such as polyurethane, resol-type phenolic resins such as phenolic resin (PF), melamine resins such as melamine resin (MF), epoxy resins such as epoxy resin (EP), and rubbers such as natural rubber (NR), styrene-butadiene rubber (SBR), chloroprene rubber (CR), nitrile rubber (NBR), and silicone rubber. From the viewpoint of heat resistance, preferred foams include, for example, foams made from polyurethane resins (e.g., polyurethane foams such as soft polyurethane foam), silicone rubber foams (foamed silicone, etc.), and the like.

[0060] 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.

[0061] The number of porous sheets included in the intercellular structure disclosed herein (e.g., the number of porous sheets accommodated in the sealed space of the bag) may be one or two or more. From the viewpoints of ease of manufacturing the intercellular structure and / or the bag, thickness reduction, etc., in some embodiments, the number of porous sheets is suitably one to ten, preferably one to five, and more preferably one to three or one to two. For example, by using a first porous sheet having a relatively high compressive strength and / or weight per area in combination with a second porous sheet having a relatively low compressive strength and / or weight per area, the total thickness of the porous sheets can be reduced while achieving a good balance of desired resilience and cushioning properties. When two or more porous sheets are used, the porous sheets may be bonded (fixed) to each other or may not be bonded to each other. Bonding two or more porous sheets to each other can be advantageous from the viewpoint of ease of manufacturing the intercellular structure and / or the bag, etc. On the other hand, not bonding two or more porous sheets to each other can be advantageous from the viewpoint of improving the cushioning properties of the intercellular structure and / or the bag, etc.

[0062] The porous sheet may be bonded to the inner or outer surface of the bag body, for example, with an adhesive or pressure-sensitive adhesive, or may not be bonded with an adhesive or pressure-sensitive adhesive, and is preferably not bonded with an adhesive or pressure-sensitive adhesive. Bonding without an adhesive or pressure-sensitive adhesive, i.e., not using an adhesive or pressure-sensitive adhesive, can suppress an increase in thermal conductivity compared to when an adhesive or pressure-sensitive adhesive is used. On the other hand, an embodiment in which the porous sheet is bonded with an adhesive or pressure-sensitive adhesive (e.g., bonded to the outer surface of the bag body) can be advantageous in terms of the ease of handling the inter-cell structure and the ease of manufacturing a battery module including the inter-cell structure.

[0063] The shape of the porous sheet is not particularly limited. In some embodiments, the shape of the porous sheet 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 rectangles).

[0064] In the intercellular structure disclosed herein, the weight of the porous sheet (in a configuration having two or more porous sheets, the total weight of the porous sheets) W Ｂ is 150 g / m ２ This means that when the porous sheet is viewed from above, the area of ​​the porous sheet is 1 m ２ This means that the weight per unit is 150g or more. Ｂ is 150 g / m ２ The porous sheet described above is likely to provide an appropriate repulsive force that can significantly contribute to improving the durability of the bag body. Ｂ is 200 g / m ２ Advantageously, it is equal to or greater than 250 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 / m ２ or more than 800 g / m ２ The weight W of the porous sheet may be equal to or greater than the weight W of the porous sheet. 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 may be less than Ｂ It is preferable that the weight W of the porous sheet is not too large from the viewpoint of reducing the weight of the intercellular structure. Ｂ is 800 g / m ２ or less, and ２or less, and ２ Below, 450g / m ２ Below, 400g / m ２ or less than 350 g / m ２ It may be the following:

[0065] In some embodiments, the weight of the porous sheet (in a configuration having two or more porous sheets, the total weight of those porous sheets) W 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 may be equal to or greater than the weight W of the porous sheet. Ｂ The upper limit is not particularly limited, and is, 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 may be less than Ｂ It is preferable that the weight of the porous sheet is not too large from the viewpoint of reducing the weight of the intercellular structure, etc. The weight of the porous sheet described above can be preferably applied, for example, to an embodiment in which a fibrous molded product (e.g., an inorganic fiber-containing sheet) is used as the porous sheet.

[0066] In some embodiments in which a foamed molded body (for example, a foam sheet) is used as the porous sheet, the weight of the porous sheet (in a configuration having two or more porous sheets, the total weight of the porous sheets) W Ｂ is 170 g / m from the viewpoint of easily obtaining an appropriate repulsion force and the effect of reducing the temperature dependency of the thickness.２ It is preferable that the weight is 200 g / m or more. ２ More preferably, it is 230 g / m or more. ２ or more, and ２ or more, and ２ or more, and ２ The weight W of the porous sheet (foamed molded article) may be more than 10 ... Ｂ is not particularly limited, and is, for example, 1000 g / m ２ or less, and ２ or less, and ２ or less, and ２ or less, 450 g / m ２ or less, 400 g / m ２ or less, 350 g / m ２ or less, 330 g / m ２ or less, 300 g / m ２ Less than (e.g., 290 g / m ２ (see below) is also acceptable.

[0067] In the technology disclosed herein, the initial thickness of the porous sheet (in a configuration having two or more porous sheets, the total thickness of those porous sheets) 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) in the manner in which the intercellular structure is used. The initial thickness of the porous sheet 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 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 and / or the bag, the initial thickness of the porous sheet 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. Furthermore, in some embodiments in which the porous sheet is disposed outside the bag body, the thickness of the porous sheet is suitably less than 20 mm, from the viewpoint of suppressing an increase in the thickness of the intercellular structure, and is preferably 15 mm or less (for example, 1 mm or more and 15 mm or less), and may be 12 mm or less, 10 mm or less, 9 mm or less, 8 mm or less, 7 mm or less, or 6 mm or less.

[0068] As the initial thickness of the porous sheet, similarly to the heat insulating layer described later, the thickness of the cross section of the porous sheet is measured using a thickness measuring device (dial thickness gauge JAN-257, probe Φ20 mm, manufactured by Ozaki Seisakusho) when no pressure is applied (when no intentional load is applied to the porous sheet), and this measurement is further carried out at any number of locations (for example, 10 locations), and the average value of the obtained values ​​can be used. That is, the initial thickness of the porous sheet can be the thickness TB of the porous sheet when no pressure is applied. NPIn an intercellular structure having a porous sheet inside a bag, the initial thickness of the porous sheet already contained in the sealed space of the bag can be estimated to be at least equal to or greater than (typically, greater than) the thickness of the porous sheet that is similarly measured without pressure after the bag is disassembled and removed from the sealed space.

[0069] In some embodiments of the intercellular structure disclosed herein, the porous sheet used to fabricate the intercellular structure (e.g., a porous sheet used by being contained in the sealed space of a bag, a porous sheet used by being disposed outside a bag, etc.) undergoes a compression test at a compression rate of 0.5 mm / min on the porous sheet alone. When the compressive stress value (applied pressure) is 3.45 MPa, the compressive strain value (hereinafter also referred to as "strain when 3.45 MPa is applied"; similar expressions apply as well) may be, for example, 25% or more, advantageously 30% or more or 35% or more, preferably 40% or more, more preferably 45% or more, or even 50% or more or 55% or more. The strain when 3.45 MPa is applied to the porous sheet may, for example, be 90% or less, 85% or less (e.g., less than 85%), 80% or less, or 75% or less. A porous sheet having a strain within any of the above-mentioned ranges when 3.45 MPa is applied is likely to stably exhibit good cushioning properties in an intercellular structure that is expected to be used in a manner in which a compressive stress of about 3.45 MPa may be applied (for example, use in a pressure range of about 0.34 MPa to about 3.45 MPa).

[0070] In some embodiments of the intercellular structure disclosed herein, the strain of the porous sheet used to fabricate the intercellular structure when subjected to 1.39 MPa may be, for example, 25% or more, advantageously 35% or more, preferably 45% or more, more preferably 50% or more or 55% or more, and may even be 60% or more or 65% or more. The strain of the porous sheet when subjected to 1.39 MPa may be, for example, 90% or less, preferably 80% or less, and may even be 75% or less. A porous sheet having a strain when compressed at 1.39 MPa within any of the above-mentioned ranges is likely to stably exhibit good cushioning properties in an intercellular structure expected to be used in a mode in which a compressive stress of around 1.39 MPa may be applied (e.g., use in a pressure range of about 0.03 MPa to about 1.39 MPa).

[0071] In some embodiments of the intercellular structure disclosed herein, the strain of the porous sheet when subjected to 1.00 MPa may be, for example, 5% or more, preferably 7% or more or 10% or more, and may be 15% or more, 20% or more, 25% or more, 30% or more, 35% or more, 40% or more, 50% or more, 55% or more, or 60% or more. The strain of the porous sheet when subjected to 1.00 MPa may be, for example, 85% or less, preferably 80% or less, and may be 75% or less or 70% or less. A porous sheet having a strain when subjected to 1.00 MPa in any of the above-mentioned ranges is likely to stably exhibit good cushioning properties in an intercellular structure expected to be used in a manner in which a compressive stress of around 1.00 MPa may be applied (e.g., use in a pressure range of about 0.03 MPa to about 1.39 MPa or a pressure range of about 0.34 MPa to about 3.45 MPa).

[0072] In some embodiments of the intercellular structure disclosed herein, the strain of the porous sheet when subjected to 0.34 MPa may be, for example, 3% or more, 5% or more, preferably 10% or more, and may be 15% or more, 20% or more, 25% or more, 30% or more, 35% or more, 40% or more, or 45% or more. The strain of the porous sheet when subjected to 0.34 MPa may be, for example, 75% or less, preferably 70% or less, and may be 65% or less, 60% or less, 50% or less, 40% or less, 35% or less, 25% or less, or 20% or less. A porous sheet having a strain at 0.34 MPa compression within any of the above-mentioned ranges is likely to stably exhibit good cushioning properties in an intercellular structure that is expected to be used in a manner in which a compressive stress of around 0.34 MPa may be applied (for example, in a pressure range of about 0.03 MPa to about 1.39 MPa or a pressure range of about 0.34 MPa to about 3.45 MPa).

[0073] The thermal conductivity of the porous sheet is not particularly limited. In some embodiments, the thermal conductivity of the porous sheet 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 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 can be measured using the same method as the method for measuring the thermal conductivity of the heat insulating layer described below.

[0074] The thermal resistance of the porous sheet is not particularly limited. In some embodiments, the thermal resistance of the porous sheet 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 m２ ) / 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 at 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 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.

[0075] <Bag> The number (number of sheets) of bag materials used to form the bag is usually 1 or more, preferably 2 or more, and usually 5 or less, preferably 4 or less, and more preferably 3 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 way, 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.

[0076] The bag body 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 ring shape. 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.

[0077] The sealing between the opposing surfaces of the bag material forms a seal portion where the innermost layers of the bag material (laminate film) are joined together to seal the sealed space. In this seal portion, the sealed space of the bag body is separated from the outside by a seal layer formed by integrating the innermost layers of the two opposing laminate films (or, if a separate welding resin layer is used to form the seal portion, the innermost layer and the welding resin layer). From the viewpoint of easily ensuring appropriate seal strength in the seal portion, the thickness of the seal layer is suitably greater 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. Since there is no metal layer in the sealing layer portion in the path from the sealed space of the bag body through the sealing layer to the outside, it is advantageous from the viewpoint of suppressing gas leakage through the sealing layer if the thickness of the sealing layer is not too large.

[0078] In the technology disclosed herein, the method for realizing a configuration in which a gas-containing fluid is contained in a sealed space partitioned by a bag material is not particularly limited. For example, the sealed space may be formed in a state in which the gas is already contained, or the gas may be generated in 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 in 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 (e.g., sodium bicarbonate) of the sodium bicarbonate or the aqueous citric acid solution may be encapsulated, or each component may be encapsulated separately, and the capsules may be broken by pressure or other means at an appropriate time to bring the two components into contact with each other to generate carbon dioxide gas. 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 with each other, and the bag can function as a gas spring by generating carbon dioxide gas at an appropriate time to inflate the bag.

[0079] The number of sealed spaces in one bag body may be one or two or more. A bag body having two sealed spaces can be formed, for example, by arranging two rectangular bag materials 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 including a bag body 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 and space utilization efficiency, the number of sealed spaces in one bag body 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 the number of sealed spaces in one bag body is one may be preferably adopted.

[0080] Furthermore, the intercell structure disclosed herein may be disposed between adjacent cells in a single structure, or in two or more structures. By disposing two or more intercell structures between cells in this manner, even if the airtightness of the sealed space of the bag in one intercell structure is accidentally lost, the presence of the remaining intercell structures 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 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 possessed by those intercell structures is suitably 20 or less, preferably 12 or less, and may be 8 or less, 4 or less, or 2 or less.

[0081] The pouch constituting the inter-cell structure 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 pouch thickness is within this range, the inter-cell structure including the pouch can adequately buffer stress generated by battery expansion. From the viewpoint of easily achieving higher buffering properties, in some embodiments, the thickness of the pouch 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. In addition, in some embodiments, the thickness of the pouch 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.

[0082] Furthermore, the pouch constituting the inter-cell structure disclosed herein may have a thickness measured under an applied pressure of 3.45 MPa (hereinafter also referred to as the "thickness when 3.45 MPa is applied") within a range of, for example, approximately 0.2 mm to 25 mm. When the pouch thickness is within this range, the inter-cell structure including the pouch can adequately buffer stress generated by battery expansion. From the viewpoint of easily achieving higher buffering properties, in some embodiments, the thickness of the pouch when 3.45 MPa is applied 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 2 mm or more. In some embodiments, the thickness of the pouch when 3.45 MPa is applied 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 bag preferably has a cushioning property such that the thickness difference between an applied pressure 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 thickness difference 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.

[0083] The thickness of the bag body when a pressure of 0.34 MPa is applied can be determined by sandwiching the bag body between two parallel metal plates having an area larger than the area S per side of the bag material facing the sealed space formed inside the bag body, using a precision universal testing machine to remove the load from the two metal plates, performing zero point correction, 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 bag body at that time. Examples of precision universal testing machines that can be used include the Autograph AGS-5kNX manufactured by Shimadzu Corporation or an equivalent. The cross-sectional thickness of the bag body can be measured using the precision universal testing machine or a thickness measuring device such as a vernier caliper. The thickness of the bag body when a pressure of 3.45 MPa is applied is measured in the same manner as the thickness of the bag body when a pressure of 0.34 MPa is applied, except that the applied pressure during measurement is 3.45 MPa.

[0084] In some embodiments in which the intercellular structure disclosed herein has a porous sheet housed in the interior space of a pouch, the pouch has an internal thickness TA IN (0.34) [mm] and the thickness TB of the porous sheet contained in the inner section of the bag when not pressurized NP The relationship between [mm] and TB is as follows: NP >TA IN (0.34); where, the inner thickness TA of the bag body when 0.34 MPa is applied IN (0.34) refers to the thickness of the sealed space inside the bag (the distance between the inner surfaces of the bag material) under the condition of an applied pressure of 3.45 MPa, and is calculated by subtracting the thickness of the bag material (laminated film) × 2 from the thickness of the bag when 3.45 MPa is applied. Here, the thickness TB of the porous sheet when not pressurized NP [mm] is the initial thickness of the porous sheet. NP >TA INSatisfying (0.34) means that when a pressure of at least 0.34 MPa is applied to the bag body, the porous sheet contained in the sealed space of the bag body is compressed in the thickness direction between the inner surfaces of the bag material. Therefore, a bag body configured to satisfy the above formula can exhibit effects such as reducing the pressure difference due to the contribution of the repulsive force of the porous sheet and thereby improving durability when at least 0.34 MPa is applied. From the viewpoint of making it easier to obtain a greater effect, TA IN (0.34) and TB NP Ratio to (TB NP / TA IN (0.34)) may be, for example, 1.5 or more, 2 or more, 5 or more, 10 or more, 15 or more, 20 or more, 25 or more, or 30 or more. NP / TA IN (0.34)) may be, for example, 100 or less, 70 or less, or 50 or less.

[0085] <Thermal Insulation Layer> The intercellular structure disclosed herein may be configured to include a thermal insulation layer. The thermal insulation layer may be disposed inside the bag (e.g., in a sealed space partitioned by the bag material) or outside the bag.

[0086] The heat 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 secondary battery (for example, a non-aqueous electrolyte secondary battery such as a lithium ion battery). In some embodiments, a heat insulating layer containing inorganic particles can be preferably used from the viewpoint of heat insulating performance, etc. 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.

[0087] 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.

[0088] 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.

[0089] 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. Examples of methods for determining the average primary particle diameter of silica particles include methods using electron microscopes such as scanning electron microscopes (SEMs) and transmission electron microscopes (TEMs). 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.

[0090] 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 for measuring using the same method as for the primary particle size can be mentioned.

[0091] 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, and preferably 350m ２ / g or less, more preferably 320m ２ / 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.

[0092] 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 measuring 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). If a nominal value for the apparent specific gravity is provided by a manufacturer or the like, that nominal value can be used.

[0093] 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.

[0094] 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, and even more preferably 80% by mass or more, and is 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.

[0095] 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.

[0096] 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, and even more preferably 5% by mass or more, and is 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, good thermal resistance is easily ensured and the heat insulating layer is easily manufactured.

[0097] 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 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.

[0098] 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 is preferably 25 μm or less, more preferably 20 μm or less, 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.

[0099] 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.

[0100] 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.

[0101] 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.

[0102] 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.

[0103] 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.

[0104] 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, 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 can be suppressed. 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 than 1 mm. By reducing the thickness of the insulating layer, the inter-cell structure 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., a dial thickness gauge JAN-257 (measuring probe Φ20 mm) manufactured by Ozaki Seisakusho) when no pressure is applied (when no intentional load is applied to the insulating layer).

[0105] 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.

[0106] 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.

[0107] 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.

[0108] 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.

[0109] 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.

[0110] 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.

[0111] 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.

[0112] 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.

[0113] 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 has stabilized, 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).

[0114] The thermal resistance of the heat insulating layer can be calculated from the thermal conductivity k1 and the thickness under pressure L1 using 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].

[0115] In some embodiments where the intercellular structure 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 disclosed herein to easily realize an intercellular structure with good thermal insulation and cushioning properties.

[0116] In some embodiments in which the intercellular structure disclosed herein includes a thermal insulation layer, the thermal insulation layer's strain at 1.00 MPa compression is suitably, for example, 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 thermal insulation layer's strain at 1.00 MPa compression 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 ranges can be used as a component of any of the intercellular structures disclosed herein to easily realize an intercellular structure with good thermal insulation and cushioning properties.

[0117] In some embodiments in which the intercellular structure disclosed herein includes a thermal insulation layer, the thermal insulation layer constituting the intercellular structure 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 thermal insulation layer is greater than 0%, and may be, for example, 3% or more, 5% or more, 7% or more, or 9% or more. A thermal insulation layer having a strain at 0.34 MPa compression within any of the above ranges is likely to realize an intercellular structure with good thermal insulation and cushioning properties (e.g., good compression characteristics in the loading-unloading test described below).

[0118] The number of heat insulating layers included in the intercellular structure 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).

[0119] 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.

[0120] 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).

[0121] 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.

[0122] 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.

[0123] 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.

[0124] 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 also 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 more, and also preferably 4 hours or less, more preferably 2 hours or less, and even more preferably 1 hour or less. When the mixing time is within the above range, the heat insulating layer can be easily produced efficiently.

[0125] 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 K 2220:2013, "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.

[0126] 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.

[0127] 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.

[0128] <Inter-cell structure> The inter-cell structure disclosed herein is used in a battery module or the like including a plurality of arranged cells, by being disposed between adjacent cells among the plurality of cells. The target cells are not limited to prismatic cells, and may be, for example, laminated cells or cylindrical cells. Furthermore, the target cells may be cells having an electrolytic solution (i.e., a liquid electrolyte) or cells having a solid electrolyte (e.g., an all-solid-state battery). The shape of the inter-cell structure can be appropriately adopted depending on the type of cell.

[0129] In addition, target devices for the battery include electric vehicles such as electric vehicles (EVs), hybrid vehicles (HVs), and plug-in hybrid vehicles (PHVs), portable electronic devices such as mobile terminals, mobile phones, and notebook computers, and wearable devices.

[0130] Fig. 1 is a perspective view schematically illustrating an example of a battery module in which inter-cell structures according to one embodiment are disposed between cells, and Fig. 2 is a cross-sectional view taken along line II-II of Fig. 1. As shown in Fig. 1, a battery module 50 includes a plurality of battery cells (here, rectangular lithium-ion battery cells) 51 arranged in the thickness direction, with an inter-cell structure 1 disposed between each of the battery cells 51. The plurality of battery cells 51 thus arranged with the inter-cell structures 1 sandwiched between them are typically restrained by applying a pressing force (compressive force) in the thickness direction via restraint plates 52a, 52a disposed at both ends, and are housed in a battery case 53 for use.

[0131] FIG. 3 shows an enlarged view of the inter-cell structure 1 shown in FIG. 2 . This inter-cell structure 1 has a bag body 30 in which two pieces of bag material 31A, 31B are sealed by bonding (e.g., heat sealing) at seal portions 32 provided along the outer edges of the bag body. An enclosed space partitioned by the bag materials 31A, 31B is formed inside the bag body. This enclosed space contains a fluid 20 containing at least a gas (e.g., air), and also contains a porous sheet 10. By sandwiching the inter-cell structure 1 configured as described above between two adjacent battery cells 51, as shown in FIG. 2 , the inter-cell structure 1 can durably exhibit a buffering function between the battery cells 51, 51, by utilizing the fluid spring (gas spring) and the resilience of the porous sheet to change the thickness of the inter-cell structure 1 in response to changes in the gap between the cells 51 (e.g., repeated expansion and contraction associated with charging and discharging). 2 and 3 illustrate a configuration in which the intercellular structure 1 includes only one porous sheet 10, but the number of porous sheets may be two or more. Furthermore, while FIGS. 1 to 3 illustrate a configuration in which the porous sheet 10 included in the intercellular structure 1 is housed in the sealed space of the bag 30, the porous sheet included in the intercellular structure may be disposed outside the bag, or may be disposed both inside the bag (i.e., in the sealed space) and outside the bag. In an embodiment in which the intercellular structure includes a porous sheet disposed outside the bag, the number of porous sheets outside the bag may be one or two or more. In an embodiment in which the intercellular structure includes two or more porous sheets disposed outside the bag, the porous sheets may be disposed separately on one side and the other side of the bag, or two or more porous sheets may be disposed on either side of the bag.

[0132] In some embodiments of the intercellular structure disclosed herein, the strain of the intercellular structure when subjected to 0.34 MPa during loading (compression) may be, for example, 3% or more or 5% or more, preferably 10% or more, and may be 15% or more, 20% or more, 25% or more, 30% or more, 35% or more, 40% or more, or 45% or more. The strain of the intercellular structure when subjected to 0.34 MPa during loading is calculated using the following formula: 1 - (thickness during loading when subjected to 0.34 MPa / thickness at 0 MPa). The strain of the intercellular structure when subjected to 0.34 MPa during loading may be, for example, 75% or less, preferably 70% or less, and may be 65% or less, 60% or less, 50% or less, 40% or less, 35% or less, 25% or less, or 20% or less. If the strain when 0.34 MPa is applied during the loading process is within any of the above-mentioned ranges, it is easy to obtain cushioning properties that allow the thickness to change with good follow-up in response to repeated cell expansion and contraction, etc. In the formula for calculating the strain when 0.34 MPa is applied during the loading process of the intercellular structure, the initial thickness of the intercellular structure measured by the method described in the Examples below is used as the value of the thickness at 0 MPa.

[0133] In some embodiments of the intercell structure disclosed herein, the strain of the intercell structure when subjected to 3.45 MPa may be, for example, 25% or more, advantageously 35% or more, preferably 45% or more, more preferably 50% or more or 55% or more, and may be 60% or more or 65% or more. The strain of the intercell structure when subjected to 3.45 MPa is calculated by the following formula: 1 - (thickness when subjected to 3.45 MPa / thickness at 0 MPa). The strain of the intercell structure when subjected to 3.45 MPa may be, for example, 90% or less, preferably 80% or less, and may be 75% or less. When the strain of the intercell structure when subjected to 1.39 MPa is within any of the above-mentioned ranges, cushioning properties are likely to be obtained that allow the thickness to change with good follow-up in response to repeated cell expansion and contraction, etc.

[0134] In some embodiments of the intercell structure disclosed herein, the strain when a load of 0.34 MPa is applied during the unloading (releasing) process of the intercell structure may be, for example, 3% or more, or 5% or more, and preferably 10% or more, and may be 15% or more, 20% or more, 25% or more, 30% or more, 35% or more, 40% or more, or 45% or more. The strain when a load of 0.34 MPa is applied during the unloading process of the intercell structure is calculated using the following formula: 1 - thickness when a load of 0.34 MPa is applied during the unloading process / thickness at 0 MPa). The strain when a load of 0.34 MPa is applied during the unloading process of the intercell structure may be, for example, 75% or less, preferably 70% or less, and may be 65% or less, 60% or less, 50% or less, 40% or less, 35% or less, 25% or less, or 20% or less. An intercell structure having a strain when a load of 0.34 MPa is applied within any of the above-mentioned ranges is likely to provide good cushioning properties.

[0135] In some embodiments of the intercellular structure disclosed herein, the amount of strain in the intercellular structure during the loading process from when an applied pressure of 0.34 MPa is reached to 3.45 MPa (i.e., the strain difference calculated by "strain when 3.45 MPa is applied - strain when 0.34 MPa is applied during the loading process") is suitably greater than 10% (e.g., 15% or more), preferably 20% or more, more preferably 25% or more, and may be 30% or more (e.g., 35% or more), 40% or more, 50% or more, 60% or more, 70% or more, or 80% or more. The amount of strain may be, for example, 95% or less, and in some embodiments, suitably 90% or less, and may be 85% or less, 80% or less, 75% or less, 70% or less, 60% or less, or 50% or less. If the strain amount during the loading process is within any of the above ranges, it is easy to obtain a cushioning property that allows the thickness to change with good follow-up in response to repeated expansion and contraction of the cells.

[0136] In some embodiments of the intercellular structure disclosed herein, the amount of strain during the unloading process of the intercellular structure from an applied pressure of 3.45 MPa to 0.34 MPa (i.e., the strain difference calculated by "strain when 3.45 MPa is applied - strain when 0.34 MPa is applied in the unloading process") may be, for example, 10% or more, preferably 20% or more, more preferably 25% or more, 30% or more (e.g., 35% or more), 40% or more, 50% or more, 60% or more, or 70% or more. The above strain amount may be, for example, 95% or less, and in some embodiments, it is suitably 90% or less, and may be 85% or less, 80% or less, 75% or less, 70% or less, 60% or less, or 50% or less. When the amount of strain during the unloading process is within any of the above-mentioned ranges, it is easy to obtain cushioning properties that allow the thickness to change with good tracking in response to repeated cell expansion and contraction, etc.

[0137] The thermal conductivity of the inter-cell structure disclosed herein is not particularly limited. In some embodiments, the thermal conductivity of the inter-cell structure 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 inter-cell structure can be measured in the same manner as the thermal conductivity of the heat insulating layer described above.

[0138] The thermal resistance of the inter-cell structure disclosed herein is not particularly limited, and can be measured in the same manner as the thermal resistance of the heat insulating layer described above.

[0139] The matters disclosed in this specification include the following: [1] An inter-cell structure disposed between adjacent cells of an arranged battery module or battery pack including a plurality of battery cells, the inter-cell structure including a bag body having a bag material made of a laminated film including a metal layer and a resin layer as a constituent material, and a fluid contained in an enclosed space partitioned by the bag material, the bag body having a seal part where innermost layers of the laminated film are joined to each other to seal the enclosed space, the thickness of the seal layer in the seal part being greater than 100 μm and not greater than 600 μm, the fluid including at least a gas, the inter-cell structure including a porous sheet, the weight of the porous sheet being 150 g / m ２ [2] An inter-cell structure disposed between adjacent cells of an arranged battery module or battery pack including a plurality of lithium ion battery cells, the inter-cell structure including a bag body having a bag material made of a laminated film including a metal layer and a resin layer as a constituent material, and a fluid contained in an enclosed space partitioned by the bag material, the bag body having a seal portion where innermost layers of the laminated film are joined to each other to seal the enclosed space, the thickness of the seal layer at the seal portion is greater than 100 μm and not more than 600 μm, the fluid includes at least a gas, the inter-cell structure including a porous sheet, and the weight of the porous sheet is 150 g / m ２ [3] An inter-cell structure disposed between adjacent cells of a battery module or battery pack including an array of a plurality of battery cells, the inter-cell structure including a bag body having a bag material made of a laminated film including a metal layer and a resin layer as a constituent material, and a fluid and a porous sheet contained in an enclosed space partitioned by the bag material, the bag body having a seal part where innermost layers of the laminated film are joined to each other to seal the enclosed space, the thickness of the seal layer in the seal part is greater than 100 μm and not more than 600 μm, the fluid includes at least a gas, and the weight of the porous sheet contained in the enclosed space is 150 g / m２ [4] An inter-cell structure disposed between adjacent cells of a battery module or battery pack including an array of lithium-ion battery cells, the inter-cell structure including a bag body having a bag material made of a laminated film including a metal layer and a resin layer as a constituent material, and a fluid and a porous sheet contained in an enclosed space partitioned by the bag material, the bag body having a seal portion where innermost layers of the laminated film are joined to each other to seal the enclosed space, the thickness of the seal layer in the seal portion being greater than 100 μm and not greater than 600 μm, the fluid includes at least a gas, and the weight of the porous sheet contained in the enclosed space is 150 g / m ２ [5] The inter-cell structure according to [1] or [2] above, wherein the porous sheet is disposed outside the bag body. [6] The bag body has an internal thickness TA when a pressure of 0.34 MPa is applied. IN (0.34) [mm] and the thickness TB of the porous sheet when not pressed NP The relationship between [mm] and TB is as follows: NP >TA IN [7] The surface area A [m 2 ] of the bag material facing the sealed space satisfies (0.34). 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 [6] above, wherein G=V / (A / 2). [8] The intercellular structure according to any one of [1] to [7] above, wherein the porous sheet comprises at least a sheet-like molded product containing inorganic fibers. [9] The intercellular structure according to [8] 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.

[10] The intercellular structure according to any one of [1] to [9] above, wherein the porous sheet comprises a sheet-like molded product containing inorganic particles and inorganic fibers.

[11] The intercellular structure according to

[10] above, wherein 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.

[0140] 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.

[0141] <Materials Used> The intercellular structures according to the examples described below were fabricated using the following materials.

[0142] (Films) A: Laminated film with the configuration shown in Table 1 (product of J Film Inc.). B: Laminated film with the configuration shown in Table 1 (product of Nihon Matai Co., Ltd.). C: Laminated film with the configuration shown in Table 1 (product of Resonac Co., Ltd.). D: Laminated film with the configuration shown in Table 1 (product of Kyodo Printing Co., Ltd.). E: Laminated film with the configuration shown in Table 1 (prepared by laminating a 100 μm thick LLDPE layer to the innermost layer (150 μm thick LLDPE layer) of a TOPPAN Co., Ltd. product). F: Laminated film with the configuration shown in Table 1 (product of Toyo Seikan Co., Ltd.). G: Laminated film with the configuration shown in Table 1 (product of Rhein Plastics Co., Ltd.). The thicknesses of each layer and total thickness of films A to D, F, and G are manufacturer's nominal values. For film E, the thickness and total thickness of the LLDPE laminated to the innermost layer are actual measurements, and the thicknesses of the other layers are manufacturer's nominal values.

[0143]

[0144] (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 100 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 200 g / m ２ Glass wool C: 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 Glass wool D: Glass wool manufactured by Paramount Glass Industry Co., Ltd. (trade name: Feather Glass FG, 24 kg / m ３ , thickness 25 mm) at 500 g / m ２ Glass wool E: Glass wool manufactured by Paramount Glass Industry Co., Ltd. (trade name: Feather Glass FG, 24 kg / m ３Polyurethane foam A: A flexible polyurethane foam (trade name: Super Sheet H3, 300 g / m2, manufactured by NHK Spring Co., Ltd.) laminated with glass wool B was used. ２ , thickness 5 mm) Polyurethane foam B: Flexible polyurethane foam manufactured by Achilles (trade name: Achilles Airon HKI, 280 g / m ２ , thickness 8mm)

[0145] 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 2.0 mm to form a coating film. The coating film was then applied to a thickness of 1.0 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 product containing inorganic fibers and inorganic particles) made from a mixture containing hydrophilic fumed silica, glass fiber, graphite, and a non-polymeric dispersant. The resulting heat insulating layer had a thickness of 1.0 mm and a density of 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).

[0146] During the manufacturing process of the thermal insulation layer, the consistency of the mixed solution 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 solution when lowered was prepared, filled with the mixed solution, and placed in a PENETRO METER manufactured by Nikka Engineering Co., Ltd., with the weight attached. Next, the position of the weight was adjusted to a position where the weight and the mixed solution came into contact, and this position was designated as the zero point. Then, at room temperature (25°C), the weight was lowered for 5 seconds (±0.1 seconds), and the depth (mm) of the weight penetrating the mixed solution was calculated as 10. 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.

[0147] 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).)

[0148] 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.

[0149] Experimental Example 1 <Preparation of Intercellular Structure> (Example 1) Two sheets of film A were cut into 54 mm squares, and one sheet of porous sheet (glass wool C) was cut into a 45 mm square. The porous sheet was sandwiched between two sheets of film A and overlapped with the heat-sealable surface (CPP layer side) of film A facing inward. Three sides of the two sheets of film 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 1.7 mm for each side (0.3 mm to 2.0 mm inward from each side). After heat-sealing one side, the sheet was cooled to 45°C before heat-sealing the next side. Next, the load was released, allowing a predetermined amount of air to enter between the two sheets of film A, and the remaining side (the fourth side) of film A was similarly heat-sealed with a seal width of 1.7 mm. In this way, an intercellular structure was obtained, consisting of a bag body configured such that air and glass wool C (a porous sheet) were contained in an enclosed space partitioned by two sheets of film A (bag material). The initial thickness (unpressurized thickness measured at atmospheric pressure at 25°C) of the obtained intercellular structure was 15 mm. The initial thickness was measured at the center of the intercellular structure using a dial 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 sealed portion (calculated by subtracting twice the total thickness of the layers of film A other than the innermost layer from the total thickness of the sealed portion measured using a dial thickness gauge H-1A manufactured by Ozaki Manufacturing Co., Ltd.) was approximately 155 μm for all four sides. The surface area (internal surface area) of the bag material constituting the bag body facing the sealed space is 50 mm x 50 mm x 2, and the volume of air contained in the sealed space (measured by the method described below) is 52.75 cm ３ From these values, the gas amount G of the inter-cell structure according to Example 1 was calculated as (52.75 × 10 －３ ) / (0.050 x 0.050 x 2 / 2) = 21.1 L / m ２ It is calculated as follows.

[0150] (Examples 2, 4 to 9, Comparative Examples 1 to 2, 4 to 6) The intercellular structures of each example were produced in the same manner as in Example 1, except that the types of film and porous sheet used were as shown in Table 2, and the amount of air when heat-sealing the fourth side was adjusted to the gas amount G shown in Table 2. The intercellular structures of Comparative Examples 1 and 2 did not have a porous sheet.

[0151] (Example 3, Comparative Example 3) The intercellular structures of each example were produced in the same manner as in Example 1, except that the types of film and porous sheet used were as shown in Table 2, the heat sealing conditions were 240°C and 2 seconds, and the amount of air when heat sealing the fourth side was adjusted to the gas amount G shown in Table 2. The intercellular structure of Comparative Example 3 did not have a porous sheet.

[0152] <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 material 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. A lid with a diameter of 49.5 mm, a thickness of 10 mm, and a 2 mm diameter through-hole formed in the center of a circular plate with a diameter of 49.5 mm and a thickness of 10 mm, and a 10 mm wide flange extending from the top end of the circular plate was placed on top to prevent air from remaining inside, and the container was filled with pure water. 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

[0153] (Compression-release cycle test) Using a hydraulic servo fatigue endurance tester (EHF UV50kN, manufactured by Shimadzu Corporation) under an environment of 25 ° C. and 50% RH, the intercellular structure according to each example was 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 was considered as one cycle, and a compression-release cycle test was performed in which this cycle was repeated 3650 times. During this time, actual measurement data of the stroke (thickness of the intercellular structure) and load were collected at 0.5 second intervals. The obtained measured data was graphed with time on the X axis and thickness change on the Y axis, and the first number of cycles at which the maximum thickness began to continuously decrease was evaluated as the cycle durability of the intercellular structure. Furthermore, for each intercellular structure of each example, the minimum thickness at the zeroth compression (thickness when 3.45 MPa was applied) and the maximum thickness at the first release (thickness when 0.34 MPa was applied) were measured. The results are shown in Table 2. For intercellular structures with a cycle durability of 3,650 cycles or more, the minimum and maximum thicknesses at the 3,650th cycle (final cycle) were also measured. The results for Examples 2 and 5 to 7 are shown in Table 3.

[0154] (Gas Reduction Rate) Bag samples for measuring the gas reduction rate were prepared in the same manner as the preparation of the intercellular structure according to each example, except that the size of the film was changed to a square shape of 179 mm on each side and the size of the porous sheet was changed to a square shape of 170 mm on each side. At that time, the gas amount G [L / m ２ ] is the gas amount G [L / m ２The amount of air when heat-sealing the fourth side was adjusted so that it was equivalent to the initial gas amount V0 [mL]. Therefore, the volume of gas contained in the sealed space of the bag sample (initial gas amount) V0 [mL] was calculated by multiplying the gas amount G [L / m ２ ] is multiplied by the area of ​​the non-sealed portion (here, 175 mm x 175 mm).

[0155] The gas reduction rate was calculated using the following formula from the volume V0 [mL] of the gas contained in the sealed space of the bag sample and the volume V1 [mL] of air assumed to remain in the sealed space of the bag sample after the bag sample was continuously pressurized at 3.45 MPa for 10 years: Gas reduction rate [%] = Total area [m ２ ] × elapsed time [days] × pressure difference between the internal pressure of the sealed space and the atmospheric pressure [atm] × gas permeability of the sealing layer [mL / (m ２ · atm · 24 hours)] / initial gas volume V0 [mL] × 100

[0156] Here, the gas permeability of the sealing layer [mL / (m ２ · atm · 24 hours)] is calculated by the gas permeability [ml · d (μm) / (m ２ · atm · 24 hours)] by the seal width [μm]. Specifically, when the material of the seal layer is CPP, the air permeability value of the CPP film is 35,188 [ml · d (μm) / (m ２ · atm · 24 hours)] is used, and when the material of the sealing layer is LLDPE, the air permeability value of the LLDPE film is 62,999 [ml · d (μm) / (m ２ The air permeability of each film was calculated by measuring the permeability of nitrogen and oxygen by differential pressure gas chromatography in accordance with JIS K7126-1 (differential pressure method) (measuring equipment: thermal conductivity detector (TCD) and flame ionization detector (FID); measurement conditions: temperature and humidity 25°C, 50% RH, test pressure 100 kPa) using the formula: air permeability = nitrogen permeability × 78.7% + oxygen permeability × 21.3%.

[0157] In the above formula, the internal air pressure of the sealed space refers to the air pressure (internal air pressure) in the sealed space when the bag sample according to each example is pressurized to 3.45 MPa. When only gas is contained in the sealed space of the bag sample, the differential pressure between the internal air pressure of the sealed space and atmospheric pressure (1 atm ≒ 0.1 MPa) can be considered to be 33.5 atm. On the other hand, when gas and a porous sheet are contained in the sealed space of the bag sample, the internal thickness (TA) of the bag sample when compressed to 3.45 MPa at a speed of 0.1 mm / sec can be considered to be 33.5 atm. IN The repulsive force R [MPa] obtained when the porous sheet alone is compressed at a speed of 0.1 mm / sec to a thickness equivalent to the internal thickness TA (3.45) [mm] can be calculated by subtracting the repulsive force R [MPa] from 3.45 MPa and converting the result into units of atm. For example, for the bag sample according to Example 1, the internal thickness TA IN (3.45) is 0.75 - 0.120 x 2 = 0.51 [mm], and the repulsive force R when glass wool C is compressed to a thickness of 0.51 mm at a speed of 0.1 mm / s is 2.95 MPa, so the pressure difference between the internal air pressure of the sealed space and atmospheric pressure is 3.45 MPa - 2.95 MPa = 0.5 MPa ≒ 5 atm.

[0158] For example, the gas reduction rate of the bag sample according to Example 1 is calculated by multiplying the total area [m ２ ]=0.175[mm]×4×155[μm]=0.0001085m ２ , Elapsed time [days] = 3650 days, Differential pressure between the internal pressure of the sealed space and the atmospheric pressure [atm] = 5 atm, Gas permeability of the sealing layer [mL / (m ２ ・atm・24 hours)]=35,188 / 1700[μm]=20.70[mL / (m ２ · atm · 24 hours)], and initial gas volume V0 [mL] = 21.1 L / m ２ × 175 mm × 175 mm = 646 mL, so gas reduction rate [%] = 0.0001085 [m ２ ] x 3650 [days] x 5 [atm] x 20.70 [mL / (m ２・atm・24 hours)] / 646 [mL] × 100 = 6.3%.

[0159] (Temperature Dependence of Thickness) Using a hydraulic servo fatigue endurance tester (EHF UV50kN, manufactured by Shimadzu Corporation) under the temperature conditions of +25°C, -30°C, and +60°C, the intercellular structures according to each example shown in Table 3 were compressed at a compression rate of 0.1 mm / sec until the compressive stress reached 1 MPa. At this time, actual measurement data of the stroke (thickness of the intercellular structure) and load were collected at 0.1-second intervals, and the thickness when a load of 0.5 MPa was applied under each temperature condition (thickness when 0.5 MPa was applied) was used as the measurement data. The thickness when a load of 0.5 MPa was applied under the temperature condition of +25°C was defined as the reference (100%), and the increase / decrease [%] in thickness when a load of 0.5 MPa was applied under the temperature conditions of -30°C and +60°C from the reference value was calculated. The results are shown in Table 3.

[0160]

[0161] As shown in Table 2, all of the intercellular structures of Examples 1 to 9 exhibited good thickness buffering properties, excellent cycle durability, and suppressed gas loss rates. Examples 1 to 7 exhibited particularly low gas loss rates. In contrast, Comparative Examples 1 to 3, in which the porous sheet was omitted from the configurations of Examples 1 to 3, exhibited significantly higher gas loss rates than Examples 1 to 3. This is thought to be primarily due to the inability to utilize the repulsive force of the porous sheet in Comparative Examples 1 to 3. Furthermore, the intercellular structure of Comparative Example 4, in which the thickness of the sealing layer was too small, exhibited low cycle durability. Comparative Example 5, in which the weight of the porous sheet was too small, did not fully utilize the effect of the porous sheet and exhibited a high gas loss rate. The intercellular structure of Comparative Example 6, in which a laminated film without a metal layer was used as the bag material, burst during the compression-release cycle test when initially compressed to a compressive stress of 3.45 MPa, and the test was discontinued.

[0162]

[0163] As shown in Table 3, the intercell structures according to Examples 2 and 5 to 7 had small variations in minimum and maximum thickness between the beginning and end of the compression-release cycle test, and exhibited good buffering capacity stably (with good durability) even after repeated compression and release many times. Although not shown in Table 3, the intercell structures according to other Examples also exhibited good buffering capacity stably, roughly similar to Examples 2 and 5 to 7. Furthermore, as can be seen from a comparison of Examples 2 and 5 to 7, the weight [g / m ２ ] was increased, the temperature dependency of the thickness was clearly reduced. In Examples 6 and 7, particularly remarkable effects were obtained.

[0164] Experimental Example 2 <Preparation of intercellular structure> (Example 10) A bag without a porous sheet in the sealed space was prepared in the same manner as Comparative Example 3, except that the amount of air when the fourth edge was heat-sealed was adjusted to the gas amount G shown in Table 3. A single piece of polyurethane foam A cut into a 50 mm square was prepared as the porous sheet. This porous sheet (polyurethane foam A) was laminated on one side of the bag, thereby obtaining an intercellular structure according to this example, which included a bag and a porous sheet arranged on the outside of the bag.

[0165] Example 11 An intercellular structure according to this example was obtained in the same manner as in Example 10, except that polyurethane foam B was used instead of polyurethane foam A.

[0166] <Measurement and Evaluation> The intercell structures according to Examples 10 and 11 were evaluated in the same manner as in Experimental Example 1, and the results obtained are shown in Table 4. For comparison, Table 4 also shows the evaluation results of the intercell structures of Comparative Examples 1 and 3 fabricated in Experimental Example 1. Note that "ne" in Table 4 indicates unevaluated.

[0167]

[0168] As shown in Table 4, the intercell structures of Examples 10 and 11, which had a porous sheet disposed on the exterior of the bag body, exhibited good thickness buffering properties, and the gas reduction rate was clearly suppressed compared to the intercell structures of Comparative Examples 1 and 3, which did not have a porous sheet, and the cycle durability was significantly improved compared to the intercell structure of Comparative Example 3. The intercell structures of Examples 10 and 11 were also excellent in the effect of reducing the temperature dependence of the thickness, and although not shown in Table 4, they stably exhibited good buffering capacity similar to Examples 2 and 5 to 7.

[0169] 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.

[0170] REFERENCE SIGNS LIST 1 inter-cell structure 10 porous sheet 20 fluid 30 bag body 31A, 31B bag material 32 seal portion 50 battery module 51 battery cell

Claims

1. An inter-cell structure disposed between adjacent cells of a battery module or battery pack including an array of multiple battery cells, the inter-cell structure comprising a bag body having a bag material made of a laminated film including a metal layer and a resin layer as a constituent material, and a fluid contained in an enclosed space partitioned by the bag material, the bag body having a seal portion where the innermost layers of the laminated film are joined together to seal the enclosed space, the thickness of the seal layer at the seal portion being greater than 100 μm and not greater than 600 μm, the fluid including at least a gas, the inter-cell structure including a porous sheet, the weight of the porous sheet being 150 g / m ２ That's it, the inter-cell structure.

2. 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 having a bag material made of a laminated film including a metal layer and a resin layer as a constituent material, and a fluid contained in an enclosed space partitioned by the bag material, the bag body having a seal portion where the innermost layers of the laminated film are joined together to seal the enclosed space, the thickness of the seal layer at the seal portion being greater than 100 μm and not greater than 600 μm, the fluid including at least a gas, the inter-cell structure including a porous sheet, the weight of the porous sheet being 150 g / m ２ That's it, the inter-cell structure.

3. The intercellular structure according to claim 1 or 2, wherein the porous sheet is housed in the sealed space.

4. Internal thickness TA of the bag when 0.34 MPa is applied IN (0.34) [mm] and the thickness TB of the porous sheet when not pressed NP The relationship between [mm] and TB is as follows: NP >TA IN The intercellular structure according to claim 3, which satisfies (0.34).

5. The intercellular structure according to claim 1 or 2, wherein the porous sheet is disposed on the exterior of the bag body.

6. 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 The inter-cell structure according to any one of claims 1 to 5, wherein G=V / (A / 2) or more.

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

8. The intercellular structure according to claim 7, 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.

9. The intercellular structure according to any one of claims 1 to 8, 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.

10. The intercellular structure according to any one of claims 1 to 9, 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.

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