Separating member and battery pack

Abstract

Provided is a partition member for partitioning unit cells of a battery pack, the partition member being configured so as to easily suppress the generation of condensed water inside the battery pack. The inner packaging material (110) is accommodated in the outer packaging material (120) to form the partition member (1). The inner packaging material (110) is formed from a porous body, and the moisture permeability of the outer packaging material (120) in an environment of 40 DEG C and 90% RH is set to 1.0 * 10 <-3 > to 5.0 * 10 < 1 > g / m2 / day.

Description

Technical Field

[0001] The present invention relates to a separator member housed in a battery pack and used for separating battery members from each other, and a battery pack.

[0002] In recent years, for secondary batteries whose use as power sources for vehicles and the like is rapidly increasing, research is being conducted on increasing the energy density of secondary batteries for the purpose of improving the degree of freedom when mounted in a limited space such as a vehicle, or for the purpose of extending the cruising range that can be achieved with a single charge. On the other hand, there is a tendency for the safety of secondary batteries to be inversely related to the energy density, and there is a tendency for the safety of secondary batteries with higher energy density to decrease. For example, for a secondary battery mounted on an electric vehicle with a cruising range of several hundred kilometers, when the secondary battery is damaged due to overcharging, internal short circuit, etc., the battery surface temperature exceeds several hundred degrees Celsius, and sometimes even approaches 1000°C.

[0003] Since secondary batteries used as power sources for vehicles and the like are usually used in the form of a battery pack composed of multiple single cells, when one of the single cells constituting the battery pack is damaged and reaches the above temperature range, it may cause damage to adjacent single cells due to heat release, and the damage may spread to the entire battery pack in a chain reaction. To prevent such a chain reaction of damage between single cells, various techniques have been proposed: a technique of providing a separator member between single cells to cool the damaged single cell; a technique of providing a porous body as a separator member between single cells.

[0004] For example, there is a separator member whose thermal resistance changes between normal times and abnormal times (see Patent Document 1).

[0005] To improve the heat insulation performance during abnormal times, there is a separator member containing powdery inorganic substances and fibrous inorganic substances and satisfying a specified density (see Patent Document 2).

[0006] In addition, there is a separator member that uses a metal layer with high barrier properties in the outer packaging material in order to retain the liquid to be housed (see Patent Document 3).

[0007] Prior Art Documents

[0008] Patent Documents

[0009] Patent Document 1: WO 2018 / 124231

[0010] Patent Document 2: WO 2019 / 107560

[0011] Patent Document 3: WO 2020 / 203646 Summary of the Invention

[0012] Problems to be Solved by the Invention

[0013] However, it is worth pointing out that in a battery pack (battery module) containing a single battery or a battery pack to which a control circuit is connected, when the humidity inside changes, condensed water that can cause micro-short circuits and corrosion of metal parts is likely to be generated. However, in conventional battery packs and battery modules, in terms of the partition member, means for easily suppressing the generation of condensed water have not actually been taken.

[0014] In addition, regarding the aforementioned prior art, the partition members described in Patent Documents 1 and 2 studied the heat insulation of the inner packaging material and did not study the case of absorbing moisture from the outside or the suitable combination of the outer packaging material and the inner packaging material for this case. In addition, the partition member described in Patent Document 3 was premised on containing a liquid inside and was studied from the viewpoint of maintaining the liquid for a long time, and is essentially an invention that blocks the exchange with external substances.

[0015] As such, the hygroscopicity of the partition member has not been sufficiently studied in the prior art.

[0016] In view of these problems of the prior art, an object of the present invention is to provide a partition member that can easily suppress the generation of condensed water and a battery pack assembled with the partition member.

[0017] Solution to the problem

[0018] The inventor of the present invention conducted in-depth research to solve the aforementioned problems and as a result found that a hygroscopic partition member can be used as a means for controlling the humidity of a battery pack, and thus the present invention was conceived.

[0019] That is, to solve the aforementioned problems, the present invention includes the following aspects.

[0020] A partition member including an outer packaging material and an inner packaging material,

[0021] The inner packaging material includes a porous body,

[0022] The water vapor permeability of the outer packaging material at 40°C and 90% RH is 1.0×10 -3 ~5.0×10 1 g / m 2 / day.

[0023] 〔2〕The partition member according to the aforementioned 〔1〕, wherein the outer packaging material and the inner packaging material are non-bonded.

[0024] 〔3〕The partition member according to the aforementioned 〔1〕 or 〔2〕, wherein there is a space not occupied by the inner packaging material with respect to the space under atmospheric pressure inside the outer packaging material.

[0025] 〔4〕The partitioning member according to any one of the foregoing 〔1〕 to 〔3〕, wherein the volume ratio of the space not occupied by the inner packaging material is 10 to 70% by volume with respect to 100% by volume of the space inside the outer packaging material.

[0026] 〔5〕The partitioning member according to any one of the foregoing 〔1〕 to 〔4〕, wherein the partitioning member is sealed with the outer packaging material.

[0027] 〔6〕The partitioning member according to any one of the foregoing 〔1〕 to 〔5〕, wherein the partitioning member absorbs moisture in the atmosphere.

[0028] 〔7〕The partitioning member according to any one of the foregoing 〔1〕 to 〔6〕, wherein the proportion of the mass of water contained in the inner packaging material is 0.40 or less with respect to the total mass of the inner packaging material.

[0029] 〔8〕The partitioning member according to any one of the foregoing 〔1〕 to 〔7〕, wherein the porous body contains fibrous inorganic substances and powdery inorganic substances.

[0030] 〔9〕The partitioning member according to any one of the foregoing 〔1〕 to 〔8〕, wherein the outer packaging material contains a thermoplastic resin.

[0031] 〔10〕The partitioning member according to any one of the foregoing 〔1〕 to 〔9〕, wherein the outer packaging material contains at least one layer selected from the group consisting of an inorganic oxide layer and a metal oxide layer.

[0032] 〔11〕The partitioning member according to any one of the foregoing 〔1〕 to 〔10〕, wherein the outer packaging material contains at least one layer selected from the group consisting of an inorganic oxide layer and a metal oxide layer, and the thickness of the layer is 0.01 to 1 μm.

[0033] 〔12〕A battery pack comprising the partitioning member according to any one of the foregoing 〔1〕 to 〔11〕 and a single battery.

[0034] 〔13〕A method of using a partitioning member, comprising: bringing moisture into contact with the partitioning member according to any one of the foregoing 〔1〕 to 〔11〕 under the condition that the relative humidity is 5% or more.

[0035] 〔14〕The method of using a partitioning member according to the foregoing 〔13〕, comprising: passing moisture through the partitioning member.

[0036] 〔15〕Method of using the partition member according to the foregoing 〔13〕 or 〔14〕, wherein, for the foregoing partition member, the moisture absorbed in an environment of 40 °C and 90% RH for 15 days is maintained for 24 hours or more in an environment of 60 °C and 10% RH.

[0037] Effects of the Invention

[0038] The partition member in the above manner is disposed in the battery pack for partitioning the battery members. By making the partition member breathable, it is possible to appropriately suppress the humidity inside the battery pack and easily suppress the generation of condensed water. Description of the Drawings

[0039] Figure 1 It is a view showing a configuration example of the partition member according to the embodiment of the present invention.

[0040] Figure 2 It is Figure 1 A cross-sectional view obtained by cutting the partition member shown in along line A-A.

[0041] Figure 3 It is a view showing an example of a single battery.

[0042] Figure 4 It is Figure 3 The front view of the single battery shown in.

[0043] Figure 5 It is Figure 3 The side view of the single battery shown in.

[0044] Figure 6 It is a top view showing an example of a battery pack.

[0045] Figure 7 It is for Figure 6 A side view schematically showing the side of the battery pack shown in with the front side side plate removed. Detailed Description of the Invention

[0046] Hereinafter, the present invention will be described. The description of the embodiments shown in the following drawings is an example, and the present invention is not limited to the configurations shown in the drawings.

[0047] <Partition Member>

[0048] The partition member according to the embodiment of the present invention is a partition member for partitioning between single batteries or between a single battery and a member other than the single battery, and includes an outer packaging material and an inner packaging material, and the inner packaging material includes a porous body. The proportion of the water content in the inner packaging material is preferably 0.40 or less relative to the total mass of the inner packaging material.

[0049] The aforementioned porous body preferably contains powdery inorganic substances and fibrous inorganic substances.

[0050] By including the aforementioned porous body in the partition member, it is possible to easily maintain the humidity inside the battery pack in which the partition member is disposed at an appropriate humidity.

[0051] In addition, it is possible to avoid a significant reduction or loss of the heat resistance and heat insulation properties of the porous body due to the pressure applied to the partition member. That is, by using the porous body of the partition member that receives the heat from the secondary battery to maintain the desired heat resistance and heat insulation properties, it is possible to block the heat transfer to other secondary batteries and the like.

[0052] The partition member configured as described above can be provided in such a manner that the aforementioned outer packaging material and the aforementioned inner packaging material are not joined.

[0053] Here, "the aforementioned outer packaging material and the aforementioned inner packaging material are not joined" means that the interfaces between the inner surface of the outer packaging material and the surface of the inner packaging material are not substantially adhered to each other, and the inner packaging material moves freely within the outer packaging material. In other words, it is preferable to be provided in such a manner that there is a space within the outer packaging material that is not occupied by the aforementioned inner packaging material. Furthermore, it is preferable to be provided in such a manner that the volume ratio of the space not occupied by the aforementioned inner packaging material is 10 to 70% by volume with respect to the space at atmospheric pressure inside the aforementioned outer packaging material. From the viewpoint of achieving both heat insulation performance, it is more preferably 10 to 60% by volume, further preferably 10 to 50% by volume, and particularly preferably 10 to 40% by volume.

[0054] Figure 1 The configuration example of the partition member of the present invention is shown. Figure 1 The front view of the partition member 1 is shown in. Figure 2 Shown in Figure 1 The cross-section on the right side when the shown partition member is cut along the line A-A is shown.

[0055] In Figure 1 and Figure 2 In the example of, the partition member 1 has an overall flat plate-like or sheet-like shape in which there are a height direction (H), a width direction (W), and a thickness direction (D). The partition member 1 has a thickness direction (D) and a plane direction (P) orthogonal to the thickness direction (D). The plane direction (P) includes the aforementioned height direction (H) and width direction (D), and a plurality of oblique directions between the height direction (H) and the width direction (D).

[0056] The separator member 1 is used to separate single cells constituting a battery pack or a single cell and a member other than the single cell in its thickness direction (D). The separator member 1 includes an inner packaging material 110, and preferably the inner packaging material 110 is sealed in a breathable outer packaging material 120 and formed into a plate shape or a sheet shape.

[0057] In addition, the thickness of the separator member 1 is preferably 0.80 to 20 mm or less, more preferably 1.0 to 10 mm.

[0058] 〔Inner packaging material〕

[0059] The inner packaging material 110 includes a porous body. The porous body included in the inner packaging material 110 includes a material having hygroscopicity, and preferably includes powdery inorganic substances and fibrous inorganic substances. In the present invention, "fibrous inorganic substance" means an inorganic substance having a shape in which the major axis is 100 times or more the minor axis, and "powdery inorganic substance" means an inorganic substance having a shape in which the major axis is less than 100 times the minor axis. It should be noted that especially in the case of fibrous substances, the "major axis" means the fiber length, and the "minor axis" means the diameter of the cross section perpendicular to the major axis direction.

[0060] The fibrous inorganic substance is preferably at least one selected from the group consisting of, for example, paper, cotton sheet, polyimide fiber, polyaramide fiber, polytetrafluoroethylene (PTFE) fiber, glass fiber, rock wool, ceramic fiber, and bio-soluble inorganic fiber. Among these, at least one selected from glass fiber, rock wool, ceramic fiber, and bio-soluble inorganic fiber is particularly preferred. Ceramic fiber is a fiber mainly composed of silica and alumina (silica: alumina = 40:60 to 0:100). Specifically, silica / alumina fiber, mullite fiber, and alumina fiber can be used.

[0061] In addition, the powdery inorganic substance is preferably at least one selected from the group consisting of, for example, silica particles, alumina particles, calcium silicate, clay mineral, vermiculite, mica, cement, pearlite, fumed silica, and aerosol. Among these, at least one selected from silica particles, alumina particles, calcium silicate, and vermiculite is particularly preferred. Among the types of calcium silicate, tobermorite, xonotlite, wollastonite, and leucite are preferred, and leucite is particularly preferred. Leucite having a petal-shaped structure maintains a porous structure even when compressed and deformed, and thus has excellent liquid retention. Clay minerals are mainly magnesium silicate (including talc and sepiolite), montmorillonite, and kaolinite.

[0062] In addition, for the purpose of blocking heat transfer when an abnormality occurs between single cells, the thermal conductivity of the aforementioned porous body is usually less than 0.20 [W / (m·K)]. Additionally, it is preferably less than 0.15 [W / (m·K)], more preferably less than 0.10 [W / (m·K)]. The lower limit is not particularly limited, and it is preferably 0.001 [W / (m·K)] or more.

[0063] From the perspective of maintaining the heat insulation performance of the partition member 1, in an environment of 23°C and 50% RH, the proportion of the mass of water that the aforementioned inner packaging material 110 can contain is preferably 0.40 or less, more preferably 0.30 or less, and further preferably 0.20 or less, relative to the total mass of the inner packaging material. The lower limit is not particularly limited, and it is preferably 0.001 or more.

[0064] 〔Outer packaging material〕

[0065] The outer packaging material 120 is preferably not joined to the inner packaging material 110. The aforementioned inner packaging material 110 is preferably sealed by the outer packaging material 120. Here, "sealed" means that all sides of the outer packaging material are sealed. Additionally, the outer packaging material 120 preferably has moisture permeability. The moisture permeability is more preferably 1.0×10 -3 ~5.0×10 1 g / m 2 / day, more preferably 5.0×10 -3 ~5.0×10 0 g / m 2 / day, further preferably 1.0×10 -2 ~5.0×10 -1 g / m 2 / day.

[0066] The upper limit of the aforementioned moisture permeability is preferably 5.0×10 1 g / m 2 / day, more preferably 1.0×10 1 g / m 2 / day, more preferably 5.0×10 0 g / m 2 / day, more preferably 1.0×10 0 g / m 2 / day, more preferably 5.0×10 -1 g / m 2 / day, more preferably 1.0×10 -1 g / m 2 / day, the lower limit of the aforementioned moisture permeability is preferably 1.0×10 -3 g / m 2 / day, more preferably 5.0×10 -3 g / m2 / day, more preferably 1.0×10 -2 g / m 2 / day.

[0067] The aforementioned moisture permeability is the amount of moisture permeated through every 1 m 2 film within 24 hours, and can be measured according to JIS Z0208:1976.

[0068] The moisture permeability can be appropriately controlled according to the composition and thickness of the film. Generally speaking, for metals, it is a value of the order of 10 -5 order of magnitude, and for inorganic oxides and metal oxides, it is a value of 10 -3 ~10 0 order of magnitude.

[0069] The outer packaging material 120 is preferably a laminated sheet.

[0070] The lamination combination of the laminated sheet is not limited to them. For example, a combination formed by laminating and laminating a sealant resin layer (first resin layer), a reinforcing layer (second resin layer), a barrier layer, a base material layer (third resin layer), a protective resin layer (fourth resin layer), etc. can be applied to the outer packaging material 120. Each layer can be bonded using an adhesive.

[0071] The aforementioned barrier layer preferably includes at least one layer selected from the group consisting of an inorganic oxide layer and a metal oxide layer.

[0072] From the viewpoints of flexibility and heat resistance, in one mode of the laminated sheet, it includes a sealant resin layer and a barrier layer. Preferably, it includes a sealant resin layer and at least one layer selected from the group consisting of an inorganic oxide layer and a metal oxide layer.

[0073] In addition, in order to impart strength and scratch resistance, in another mode of the laminated sheet, from the inside of the inner package body toward the outside of the partition member, it includes at least one selected from the group consisting of: (1) a sealant resin layer, a reinforcing layer, and a barrier layer; (2) a sealant resin layer, a barrier layer, and a protective resin layer; and (3) a sealant resin layer, a reinforcing layer, a barrier layer, and a protective resin layer.

[0074] In the partition member 1 of the present invention, the outer packaging material 120 stores a liquid in its internal space. For example, by sandwiching the inner packaging material 110 with a barrier film having two or folded sealant resin layers, and heat-sealing and bonding the edge portion 120a of the outer packaging material 120 in contact with the two sealant resin layers, a seal portion is formed by this joining.

[0075] In addition, the outer packaging material 120 preferably has flexibility and can deform according to external pressures such as the expansion or contraction of the single cell, and sometimes does not have flexibility.

[0076] The barrier film contained in the outer packaging material 120 includes a base material layer and an inorganic oxide film and a metal oxide film formed on at least one side of the base material layer.

[0077] The base material layer (the third resin layer) is preferably a layer containing a resin. The type of the resin is not particularly limited, and examples thereof include polyolefin resins such as homopolymers or copolymers of ethylene, propylene, and butene; amorphous polyolefin resins such as cyclic polyolefins; polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN); polyamide resins such as nylon 6, nylon 66, nylon 12, and copolyamide; partially hydrolyzed ethylene-vinyl acetate copolymer (EVOH), polyimide resins, polyetherimide resins, polysulfone resins, polyethersulfone resins, polyetheretherketone resins, polycarbonate resins, polyvinyl butyral resins, polyarylate resins, fluororesins, acrylic resins, biodegradable resins, and the like. Among them, from the viewpoint of heat resistance when forming the oxide film, a polyester resin is preferred, and polyethylene terephthalate (PET) or polyethylene naphthalate (PEN) is particularly preferred.

[0078] The thickness of the base material layer is not particularly limited. From the viewpoint of durability, it is preferably 5 μm or more, more preferably 10 μm or more. In order to ensure flexibility, it is preferably 200 μm or less, more preferably 100 μm or less, further preferably 50 μm or less, and particularly preferably 30 μm or less.

[0079] The barrier layer is preferably at least one layer selected from an inorganic oxide layer and a metal oxide layer. By providing the barrier layer, a control function for water permeability and oxygen permeability can be imparted. The formation material of the inorganic oxide film is not particularly limited, and examples thereof include silicon oxide, silicon carbonitride oxide, silicon oxynitride oxide, silicon carbon oxynitride oxide, aluminum oxide, aluminum carbonitride oxide, and aluminum oxynitride oxide. The formation materials of the metal oxide film include aluminum, copper, titanium, palladium, and the like. It should be noted that the inorganic oxide film and the metal oxide film may each have a single-layer structure or a laminated structure. In this case, each oxide film layer may be formed of the same material or different materials.

[0080] The thickness of at least one layer selected from an inorganic oxide layer and a metal oxide layer is not particularly limited. In order to improve the barrier property, it is preferably 0.01 μm or more, more preferably 0.02 μm or more. On the other hand, in order to prevent cracks and the like, it is preferably 1 μm or less, more preferably 0.5 μm or less, and further preferably 0.1 μm or less.

[0081] The method for forming an inorganic oxide film or a metal oxide film on the substrate layer is not particularly limited, and any method can be used according to the materials used. Specifically, methods such as evaporation coating method and coating method can be used. Among them, from the viewpoint of obtaining a uniform thin film with high barrier properties, the evaporation coating method is preferred. This evaporation coating method includes methods such as physical vapor deposition (PVD), chemical vapor deposition (CVD), and atomic layer epitaxy (ALD). As the physical vapor deposition method, vacuum evaporation, ion plating, sputtering, etc. can be cited. As the chemical vapor deposition method, plasma CVD using plasma, catalytic chemical vapor growth method (Cat-CVD) in which a material gas is catalytically thermally decomposed using a heating catalyst, etc. can be cited. Among them, from the aspect of being able to perform uniform film formation at high speed, the vacuum evaporation coating method is particularly preferred.

[0082] The sealant resin layer (second resin layer) included in the outer packaging material 120 is a layer containing at least one of a thermosetting resin and a thermoplastic resin. As the sealant resin layer, at least one of a thermosetting resin and a thermoplastic resin can be used, and a thermoplastic resin is particularly preferably used. The type of the sealant resin is not particularly limited, and examples thereof include polyolefin resins such as homopolymers or copolymers of ethylene, propylene, butene, etc.; amorphous polyolefin resins such as cyclic polyolefin; polyester resins such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), etc.; polyvinyl butyral resins, acrylic resins, biodegradable resins, etc. Among them, from the viewpoint of the melting characteristics at low temperature for obtaining the function of releasing the liquid inside the outer packaging material to the outside during abnormal heat release, it is preferred to use at least one selected from polyolefin resins such as high-pressure low-density polyethylene (LDPE), linear low-density polyethylene (LLPDE), and polypropylene resin. Furthermore, from the viewpoints of long-term storage properties and versatility within the temperature range commonly used as a separator member for a battery pack, an unstretched polypropylene resin is more preferably used.

[0083] The moisture permeability of the sealant resin layer is not limited, and the moisture permeability in an environment of 40°C and 90% RH is preferably 100 g / m 2 / day or less, more preferably 50 g / m 2 / day or less, and further preferably 20 g / m 2 / day or less. The smaller the moisture permeability of the sealant resin layer, the more the release of water vapor permeating through the sealant resin can be suppressed, and therefore, the heat transfer performance of the separator member can be maintained for a long time. The lower limit of the moisture permeability of the sealant resin layer is not particularly limited, and the lower limit is usually 1 g / m 2 / day or more.

[0084] The thickness of the sealant resin layer is not particularly limited. From the perspective of ensuring sealing performance, its thickness is preferably 10 μm or more, more preferably 20 μm or more, and further preferably 30 μm or more. In addition, in order to ensure flexibility, the thickness of the sealant resin layer is preferably 120 μm or less, more preferably 100 μm or less, and further preferably 80 μm or less.

[0085] The reinforcing layer (second resin layer) is a resin-containing layer. The type of resin is not particularly limited, and examples thereof include polyolefin resins such as homopolymers or copolymers of ethylene, propylene, and butene; amorphous polyolefin resins such as cyclic polyolefins; polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN); polyamide resins such as nylon 6, nylon 66, nylon 12, and copolyamide; partially hydrolyzed ethylene-vinyl acetate copolymer (EVOH), polyimide resins, polyetherimide resins, polysulfone resins, polyethersulfone resins, polyetheretherketone resins, polycarbonate resins, polyvinyl butyral resins, polyarylate resins, fluororesins, acrylic resins, biodegradable resins, etc. Among them, from the perspective of being able to impart heat resistance and mechanical strength as an outer packaging material, polyamide resins such as nylon 6 and polyester resins such as polyethylene terephthalate are preferred, and from the perspective of improving the pinhole resistance of the metal layer, polyamide resins such as nylon 6 are further preferred. The reinforcing layer can be only 1 layer, or 2 or more layers can be laminated. In addition, in the case of 2 or more layers, they can be selected from different resin layers or from the same resin layer.

[0086] The thickness of the reinforcing layer is not particularly limited. From the perspective of being able to impart mechanical strength, it is preferably 5 μm or more, more preferably 10 μm or more, and further preferably 15 μm or more. In order to ensure flexibility, it is preferably 100 μm or less, more preferably 50 μm or less, and further preferably 30 μm or less.

[0087] The protective resin layer (fourth resin layer) is a layer containing a resin. The type of the resin is not particularly limited, and examples thereof include polyolefin resins such as homopolymers or copolymers of ethylene, propylene, and butene; amorphous polyolefin resins such as cyclic polyolefin; polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN); polyamide resins such as nylon 6, nylon 66, nylon 12, and copolyamide; partially hydrolyzed ethylene-vinyl acetate copolymer (EVOH), polyimide resins, polyetherimide resins, polysulfone resins, polyethersulfone resins, polyetheretherketone resins, polycarbonate resins, polyvinyl butyral resins, polyarylate resins, fluororesins, acrylic resins, biodegradable resins, and the like. Among them, from the viewpoint of being able to impart heat resistance and mechanical strength as an outer packaging material, polyamide resins such as nylon 6 and polyester resins such as polyethylene terephthalate are preferred. The protective resin layer may be only 1 layer, or 2 or more layers may be laminated. In addition, in the case of 2 or more layers, they may be selected from different resin layers or the same resin layer.

[0088] The thickness of the protective resin layer is not particularly limited. From the viewpoint of being able to impart mechanical strength, it is preferably 5 μm or more, more preferably 10 μm or more, and still more preferably 15 μm or more. In order to ensure flexibility, it is preferably 100 μm or less, more preferably 50 μm or less, and still more preferably 30 μm or less.

[0089] The thickness of the outer packaging material 120 is not particularly limited. Considering the thicknesses of the above-mentioned respective layers, from the viewpoint of mechanical strength, its thickness is preferably 20 μm or more, more preferably 30 μm or more, and still more preferably 40 μm or more. In addition, in order to ensure flexibility, the thickness of the outer packaging material 120 is preferably 220 μm or less, more preferably 150 μm or less, and still more preferably 110 μm or less.

[0090] The moisture permeability of the aforementioned outer packaging material 120 under the environment of 40 °C and 90% RH is preferably 1.0×10 -3 ~5.0×10 1 g / m 2 / day. From the viewpoint of keeping the absorbed liquid in the porous body as much as possible, it is more preferably 1.0×10 -2 ~2.0×10 1 g / m 2 / day, and still more preferably 5.0×10 -2 g~1.0×10 1 g / m 2 / day.

[0091] In Figure 1In the example shown, the outer packaging material 120 is provided with a sealing portion 120a for sealing its edge portion, and the inner packaging material 110 is received in the internal space 111 formed in the outer packaging material 120 by the sealing of the sealing portion 120a. In Figure 1 In the example shown, a gap 120b is provided between the sealing portion 120a and the inner packaging material 110 within the internal space 111. In other words, when looking down at the front of the partition member 1, the internal space 111 includes a first region S1 where the outer packaging material 120 and the inner packaging material 110 overlap, and a second region S2 where the outer packaging material 120 and the inner packaging material 110 do not overlap. Among them, the gap 120b is not essential. When there is no fluid (gas and liquid) in the gap 120b, a state where the inner surfaces of the outer packaging material 120 are in contact with each other can be presented. It should be noted that in the present invention, the volume of the internal space 111 is defined as the product of the area of the internal space 111 and the thickness of the inner packaging material 110. In addition, the arrangement of the inner packaging material does not necessarily need to be at the center of the internal space, and it does not necessarily need to be parallel to the outer packaging material.

[0092] As a means for imparting air permeability to the outer packaging material 120, the following can be cited: forming the outer packaging material 120 using a material having air permeability. Or, the following can be cited: forming the outer packaging material 120 using a material having gas barrier properties, enclosing the inner packaging material 110 therein, and partially providing a breathable portion on the outer packaging material 120.

[0093] <Method of using the partition member>

[0094] One aspect of the present invention includes causing the partition member having the above-described configuration to absorb moisture in the atmosphere. In order to suppress the humidity inside the battery pack, it is preferable that: (1) contact with moisture; (2) cause the contacted moisture to permeate through the inside of the partition member; and (3) retain the permeated moisture inside the partition member.

[0095] In aspect (1), it is preferable that moisture comes into contact with the partition member at a relative humidity of 5% or more.

[0096] In aspect (2), it is more preferable that, due to the configuration of the partition member as described above, a moisture concentration gradient is formed between the inside and the outside of the partition member, causing moisture to permeate through.

[0097] In aspect (3), it is preferable that the moisture absorbed in an environment of 40°C and 90% RH for 15 days is retained for 4 hours or more, more preferably 24 hours or more, in an environment of 60°C and 10% RH.

[0098] The higher the moisture permeability of the outer packaging material, the easier it is for moisture to penetrate from the outside and the easier it is to release moisture from the inside. By controlling the composition and thickness, the desired moisture retention time can be adjusted.

[0099] <Battery pack>

[0100] Next, the battery pack to which the separation member 1 is applied will be described. The battery pack can be applied to, for example, battery packs mounted in electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), electric heavy equipment, electric motorcycles, electric assist bicycles, ships, airplanes, trams, uninterruptible power supplies (UPSs), household energy storage systems, battery systems for stabilizing power systems using renewable energy such as wind energy / solar energy / tidal energy / geothermal energy, etc. Among them, the battery pack can also be used as a power source for supplying power to equipment other than the above-mentioned EVs, etc.

[0101] 〔Single battery〕

[0102] Figure 3 is a plan view showing an example of a single battery constituting the battery pack, Figure 4 is Figure 3 the front view of the single battery shown in Figure 5 is the right side view of the single battery. The single battery 200 is formed in a rectangular parallelepiped shape having a height direction (H), a width direction (W), and a thickness direction (D), and terminals 210 and 220 are provided on its upper surface. The single battery 200 is, for example, a lithium-ion secondary battery having a positive electrode, a negative electrode, and an electrolyte, and the positive electrode and the negative electrode can absorb / storage and release lithium ions. In addition to lithium-ion secondary batteries, lithium-ion all-solid-state batteries, nickel-metal hydride batteries, nickel-cadmium batteries, lead-acid storage batteries, etc. can be applied.

[0103] 〔Battery pack〕

[0104] Figure 6 shows a top view of the battery pack 100 formed by using a plurality of single batteries 200, Figure 7 is a schematic side view showing the state after removing the side plate 300d from the battery pack 100 shown in Figure 6 . In Figure 6 and Figure 7 , the battery pack 100 includes a housing 300 and a plurality of single batteries 200 housed in the housing 300. The housing 300 has a bottom plate 300e, and side plates 300a, 300b, 300c, and 300d erected along the outer periphery of the bottom plate 300e. InFigure 6 and Figure 7 In Figure 7 , five single cells 200 are illustrated as an example, but the number of single cells can be appropriately selected.

[0105] Inside the housing 300, a plurality of single cells 200 are arranged along the thickness direction, and the above-described partition member 1 is disposed between the single cells 200. The positive terminals (e.g., terminal 210) and the negative terminals (e.g., terminal 220) of the single cells 200 adjacent (opposite) to each other across the partition member 1 are electrically connected in series by a bus bar 301, so that the battery pack 100 outputs a specified power. As Figure 7 shown, a partition member 1A is disposed between the upper surface of the bottom plate 300e of the housing 300 and each single cell 200 in the battery pack 100. The partition member 1A has the same configuration as the partition member 1.

[0106] Embodiment

[0107] Next, embodiments of the present invention will be described, but the present invention is not limited to these examples.

[0108] (Embodiment 1)

[0109] A barrier film (BR-PET manufactured by Toray Film Processing Co., Ltd., model: 1517, thickness: 12 μm) having alumina formed thereon by vapor deposition on a PET substrate as an outer packaging material 120 and a film (CPP manufactured by Toyobo Co., Ltd., model: P1153, thickness: 60 μm) formed of unstretched polypropylene as a sealant resin layer are laminated with the aluminum vapor deposition surface in contact with the adhesive layer by a two-component curable polyurethane-based adhesive layer having a thickness of 5 μm, to obtain a laminated barrier film with a sealant resin layer having a thickness of 77 μm and a moisture permeability of 0.2 g / m 2 / day (under environmental conditions of 40°C and 90% RH).

[0110] The outer packaging material 120 is cut into a rectangle having a longitudinal length of 100 mm and a transverse length of 160 mm, two pieces are overlapped, and three sides are heat-sealed (temperature: 165°C, 3 seconds) with a sealing width of 1 cm.

[0111] A porous body (a fiber sheet carrying powdery inorganic substances, thickness: 0.9 mm, density: 0.29 g / cm 3 , dry weight: 2.35 g) cut into a rectangle having a longitudinal length of 6 cm and a transverse length of 12 cm as an inner packaging material 110 is received from the non-welded portion of the outer packaging material 120, and the non-welded portion is heat-sealed with a sealing portion width of 1 cm, thereby performing sealing, and the excess outer periphery is cut off, thereby manufacturing a partition member having a longitudinal length of 90 mm, a transverse length of 150 mm, a sealing width of 5 mm at the edge portion, and a thickness of 1.1 mm.

[0112] The volume ratio of the space not occupied by the inner packaging material to the volume of the space 100% by volume inside the outer packaging material under atmospheric pressure with respect to the partition member is 34% by volume.

[0113] [Weight evaluation 1]

[0114] The obtained partition member was stored for 1 day in a temperature- and humidity-controlled environment of 23°C and 50% RH, and the weight was measured. Subsequently, it was stored in a temperature- and humidity-controlled chamber maintained at 40°C and 90% RH, and the water absorption was evaluated based on the difference in weight before and after storage in the environment of 40°C and 90% RH. The storage period in the environment of 40°C and 90% RH was set to 15 days. The obtained results are shown in Table 1.

[0115] [Weight evaluation 2]

[0116] Immediately after Weight evaluation 1, the partition member was stored in a temperature- and humidity-controlled chamber maintained at 60°C and 10% RH, and the time required for the water inside the partition member to be released to the outside and reach a weight lower than that before the start of Weight evaluation 1 was measured. The obtained results are shown in Table 1.

[0117] (Example 2)

[0118] A barrier film in which alumina was formed on a PET substrate by vapor deposition (BR-PET manufactured by Toray Film Processing Co., Ltd., model: 1517, thickness: 12 μm) as the outer packaging material 120 and a film formed of unstretched polypropylene (CPP manufactured by Toyobo Co., Ltd., model: P1153, thickness: 60 μm) as a sealant resin layer formed of unstretched polypropylene were laminated using a two-component curable polyurethane-based adhesive layer with a thickness of 5 μm in such a manner that the aluminum vapor deposition surface was in contact with the adhesive layer, to obtain a laminated barrier film with a sealant resin layer having a thickness of 77 μm and a water vapor transmission rate of 0.2 g / m 2 / day (under the environmental conditions of 40°C and 90% RH).

[0119] Two samples were prepared by cutting the outer packaging material 120 into rectangles with a longitudinal length of 100 mm and a transverse length of 160 mm.

[0120] Next, a porous body (a fiber sheet carrying powdery inorganic substances, thickness: 0.9 mm, density: 0.29 g / cm 3 , dry weight: 2.35 g) obtained by cutting the porous body contained in the inner packaging material 110 into a rectangle with a longitudinal length of 6 cm and a transverse length of 12 cm was sandwiched between two outer packaging materials 120. At this time, the sealant resin layer of the outer packaging material 120 was made to face the inside.

[0121] The outer packaging material and the inner packaging material are integrally welded over the entire surface using a roll laminator with the roll temperature set to 165°C, and the excess outer periphery is cut off, thereby producing a partition member having a length of 90 mm, a width of 150 mm, and a thickness of 1.1 mm.

[0122] The volume ratio of the space not occupied by the inner packaging material with respect to the space of 100% by volume under atmospheric pressure inside the outer packaging material of the partition member is 5% by volume.

[0123] For this partition member, the same operation as in Example 1 was performed for weight evaluation. The obtained results are shown in Table 1.

[0124] (Example 3)

[0125] Using a two-component curable polyurethane-based adhesive layer with a thickness of 5 μm, a PET film with a thickness of 12 μm as the outer packaging material 120 was laminated with a sealant resin layer formed of unstretched polypropylene to obtain a laminated film with a thickness of 77 μm and a moisture permeability of 20 g / m 2 / day (under environmental conditions of 40°C and 90% RH) with a sealant resin layer. Except for this, a partition member was produced using the same method as in Example 1.

[0126] The volume ratio of the space not occupied by the inner packaging material with respect to the space of 100% by volume under atmospheric pressure inside the outer packaging material of the partition member is 34% by volume.

[0127] For this partition member, the same operation as in Example 1 was performed for weight evaluation. The obtained results are shown in Table 1.

[0128] (Comparative Example 1)

[0129] An insulating material (a fiber sheet carrying powdery inorganic substances, with a thickness of 0.9 mm and a density of 0.29 g / cm 3 and a dry weight of 2.35 g) that is not sealed by the outer packaging material around it and is cut into a rectangle with a length of 6 cm and a width of 12 cm was used as the partition member, and the same operation as in Example 1 was performed for weight evaluation. The obtained results are shown in Table 1.

[0130] [Table 1]

[0131]

[0132] From the evaluation results of the foregoing Examples and Comparative Examples, it can be confirmed that the partition members of Examples 1 to 3 having an outer packaging material can absorb moisture. During the test period of each Example, a tendency of water absorption saturation was observed for Example 3, but a tendency of further water absorption was observed for Examples 1 and 2, and it can be considered that they can all absorb moisture equally.

[0133] On the other hand, it was confirmed that in Example 1 and Example 2 using the packaging material with high water vapor barrier property obtained by using the substrate layer formed with a metal oxide film, since the release rate of the absorbed moisture was slow, the period of retaining moisture in the partition member was long, and the humidity could be controlled for a longer period.

[0134] From the evaluation results, it was found that by using the partition member of each example, the partition member could absorb the moisture outside it and retain the moisture inside for a certain period of time, and the partition member could control the humidity of the battery pack.

[0135] In addition, regarding Example 1 without the joint surface between the outer packaging material and the inner packaging material and Example 2 with the joint surface, it was confirmed that Example 1 had better hygroscopicity. It was considered that this was because an air layer existed at the interface between the outer packaging material and the inner packaging material, and furthermore, the surface area of the inner packaging material increased, so the moisture-absorbing area increased.

[0136] The configurations of the partition member and the battery pack of the present invention described above are examples, and appropriate changes can be made according to design requirements and the like without departing from the gist of the present invention.

[0137] It should be noted that when expressed as "X to Y" or "X~Y" (X and Y are arbitrary numbers) in this specification, unless otherwise specified, it includes the meaning of "X or more and Y or less" as well as the meanings of "preferably greater than X" and "preferably less than Y". Furthermore, when expressed as "X or more" (X is an arbitrary number), unless otherwise specified, it includes the meaning of "preferably greater than X", and when expressed as "Y or less" (Y is an arbitrary number), unless otherwise specified, it includes the meaning of "preferably less than Y".

[0138] Explanation of Reference Numerals

[0139] 1 Partition member

[0140] 100 Battery pack

[0141] 110 Inner packaging material

[0142] 120 Outer packaging material

[0143] 200 Single battery

[0144] 300 Housing

Claims

1. A separating member, which comprises an outer packaging material and an inner packaging material, wherein the inner packaging material comprises a porous body, The moisture permeability of the outer packaging material at 40°C and 90% RH is 1.0×10 -3 ~5.0×10 1 g / m 2 / day.

2. The separating member according to claim 1, wherein and the outer packaging material and the inner packaging material are non-bonded.

3. The separating member according to claim 1, wherein, Relative to the space under atmospheric pressure inside the outer packaging material, there is a space not occupied by the inner packaging material.

4. The separating member according to claim 1, wherein, Relative to 100% by volume of the space inside the outer packaging material, the volume ratio of the space not occupied by the inner packaging material is 10 to 70% by volume.

5. The separating member according to claim 1, wherein, The separating member is sealed by the outer packaging material.

6. The separating member according to any one of claims 1 to 3, wherein, The separating member absorbs moisture in the atmosphere.

7. The separating member according to any one of claims 1 to 3, wherein, The proportion of the mass of water contained in the inner packaging material is 0.40 or less relative to the total mass of the inner packaging material.

8. The separating member according to any one of claims 1 to 3, wherein, The porous body comprises fibrous inorganic substances and powdery inorganic substances.

9. The partition member according to any one of claims 1 to 3, wherein, The outer packaging material comprises a thermoplastic resin.

10. The partition member according to any one of claims 1 to 3, wherein The outer packaging material comprises at least one layer selected from the group consisting of an inorganic oxide layer and a metal oxide layer.

11. The partition member according to any one of claims 1 to 3, wherein, The outer packaging material comprises at least one layer selected from the group consisting of an inorganic oxide layer and a metal oxide layer, and the thickness of the layer is 0.01 to 1 μm.

12. A battery pack, which comprises the separating member according to any one of claims 1 to 3 and a single battery.

13. A method of using a separating member, comprising: Under the condition that the relative humidity is 5% or more, bring moisture into contact with the separating member according to any one of claims 1 to 3.

14. The method of using the separating member according to claim 13, comprising: Let the moisture pass through the separating member.

15. The method of using the partition member according to claim 13, wherein, For the separating member, keep the moisture absorbed in an environment of 40°C and 90% RH for 15 days in an environment of 60°C and 10% RH for 24 hours or more.

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