Heat insulation sheet and power supply device including the same

Abstract

Provided is an insulating sheet for which insulation performance is maintained while manufacturing costs are lowered. An insulating sheet (10) comprises a middle layer (11) and surface layers (12) layered on surfaces of the middle layer (11). The surface layers (12) have a heat conductivity of 0.50 W / m∙K or less in the direction of thickness, and the middle layer (11) has a heat conductivity of 1.00 W / m∙K or more in the direction of thickness. The pore diameter of the surface layers (12) may be 50 µm or less. This configuration imparts insulating properties to the surface layers (12) and consequently prevents fire from spreading, and eliminates the need to seal the surface layers (12), thus making it possible to provide the advantageous feature of being able to carry out production with ease and at a low cost.

Description

Technical Field

[0001] The present invention relates to a heat insulating sheet and a power supply device including the same.

Background Art

[0002] Sheet materials having heat insulating properties are used in various applications, such as spacers for heat insulation and insulation of secondary battery cells, explosion-proof sheets, or sheet materials for covering members having a temperature difference such as refrigerators. As an example, a spacer for heat insulation of a secondary battery cell will be described. A power supply device in which a plurality of secondary battery cells are stacked is used as a drive power supply for electric vehicles such as electric cars, hybrid cars, electric buses, and trains, or as a backup power supply for factories and base stations, and further as a home storage battery (for example, Patent Documents 1 and 2). In recent years, there has been a demand for weight reduction and high capacity of power supply devices, and high-capacity types such as lithium-ion secondary batteries are used for secondary battery cells.

[0003] On the other hand, when a large number of secondary battery cells are used, due to some abnormality, one secondary battery cell may become hot and thermal runaway may occur, and the high temperature may propagate to other adjacent secondary battery cells, resulting in a phenomenon called thermal runaway chain reaction. In particular, in the case of high-capacity batteries such as lithium-ion secondary batteries, the heat generation amount increases as the energy capacity increases. Therefore, from the viewpoint of ensuring safety, it is desired to suppress the occurrence of such thermal runaway chain reaction.

[0004] Improving the heat insulation performance is considered effective for suppressing thermal runaway. Improving the heat insulation performance means reducing the thermal conductivity. Therefore, in order to prevent the occurrence of thermal runaway chain reaction in a power supply device in which secondary battery cells are stacked, it is conceivable to interpose an insulating sheet between the secondary battery cells.

[0005] On the other hand, when the present inventor examines the process of thermal runaway occurrence, it is found that in some of the plurality of secondary battery cells, hot spots where a part of the secondary battery cell becomes locally high temperature are generated, and high heat propagates from this part to adjacent secondary battery cells, causing thermal runaway chain reaction to spread.

[0006] However, from the viewpoint of preventing thermal runaway, when the heat insulation performance is improved, due to the low thermal conductivity, as shown in the schematic cross-sectional view of FIG. 4, even if a hot spot HS occurs in any of the secondary battery cells 1, this high heat cannot be conducted and dissipated by the heat insulation sheet 10X, and as a result, the generation of high temperature cannot be suppressed and thermal runaway occurs. On the other hand, if the thermal conductivity is increased, the heat insulation performance cannot be exhibited and high temperature is propagated to adjacent secondary battery cells, and the occurrence of thermal runaway cannot be suppressed. Thus, suppressing the occurrence of hot spots and preventing thermal runaway are contradictory characteristics and it has been difficult to achieve both.

[0007] In contrast, a configuration has been proposed in which a composite sheet including a heat insulation layer and heat conduction sheets arranged on both sides thereof is provided between secondary battery cells (Patent Document 2). According to this, it is said that the heat dissipation from the battery cell to the housing is excellent and the heat insulation between adjacent battery cells is excellent.

[0008] However, in this configuration, since graphite is used for the heat conduction sheet, there is a possibility that conductive graphite powder is generated from the graphite sheet. Such graphite powder may adhere to the electronic circuit and cause problems such as a short circuit. For this reason, as shown in FIG. 19, in the composite sheet including the heat insulation layer 95, the graphite sheet is sandwiched between the first insulating sheet 93 and the second insulating sheet 94 having larger dimensions than the graphite sheet constituting the heat conduction sheet 92, and it is necessary to seal outside the outer peripheral edge of the graphite sheet. Such processing for sealing is laborious and increases the cost. In addition, the number of parts increases, leading to an increase in the thickness of the composite sheet. Particularly in in-vehicle power supply devices, while high output and miniaturization are strongly required, when the number of stacked secondary battery cells increases for high output, the number of composite sheets interposed between the secondary battery cells also increases accordingly, resulting in an increase in the thickness of the entire power supply device, as well as an increase in weight and an increase in manufacturing cost including processing cost.

[0009] In this configuration, a polyethylene terephthalate (hereinafter referred to as PET) film is used for the insulating sheet, and a PET non-woven fabric impregnated with silica xerogel is used for the heat insulation layer. However, there is also a problem that the PET film shrinks and perforates due to the heat of hot spots, and eventually the insulation between adjacent cells cannot be maintained.

Prior Art Documents

Patent Documents

[0010]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0011] The present invention has been made in view of such a background, and one of its objects is to provide a heat insulation sheet that reduces processing costs while maintaining heat insulation performance, and a power supply device including the same. Means for Solving the Problems and Effects of the Invention

[0012] According to the heat insulation sheet according to the first aspect of the present invention, it includes an intermediate layer and a surface layer laminated on the surface of the intermediate layer, the heat conductivity in the thickness direction of the surface layer is 0.50 W / m·K or less, the heat conductivity in the thickness direction of the intermediate layer is 1.00 W / m·K or more, and the pore diameter of the surface layer is 50 μm or less. and the compression ratio of the surface layer when compressed at 100 kPa is 10% or more With the above configuration, the surface layer has heat insulation properties to prevent similar burning, and the advantage is obtained that the production can be easily and inexpensively performed without the need for sealing the surface layer.

[0013] Further, according to the heat insulating sheet according to the second aspect of the present invention, in addition to any of the above configurations, it includes an intermediate layer and a surface layer laminated on the surface of the intermediate layer, the surface layer has a thermal conductivity in the thickness direction of 0.50 W / m·K or less, the intermediate layer has a thermal conductivity in the thickness direction of 1.00 W / m·K or more, and the air permeability resistance of the surface layer can be 3 to 5000 sec / 100 mL with a Gurley standard densitometer conforming to the JIS P 8117 (2009) test. With the above configuration, while providing heat insulation property to the surface layer to prevent quasi-burning, the advantage is obtained that the manufacturing can be easily and inexpensively carried out without the need for sealing the surface layer.

[0014] Furthermore, according to the heat insulating sheet according to the third aspect of the present invention, in addition to any of the above configurations, the surface layer can be laminated on both sides of the intermediate layer respectively.

[0015] Furthermore, according to the heat insulating sheet according to the fourth aspect of the present invention, in addition to any of the above configurations, the thermal conductivity of the intermediate layer in the plane direction can be 1000 W / m·K or less.

[0016] Furthermore, according to the heat insulating sheet according to the fifth aspect of the present invention, in addition to any of the above configurations, the thermal conductivity of the intermediate layer in the thickness direction can be 3.00 W / m·K or less.

[0017] Furthermore, according to the heat insulating sheet according to the sixth aspect of the present invention, in addition to any of the above configurations, the thermal conductivity of the intermediate layer in the plane direction can be 5 times or more the thermal conductivity in the thickness direction. With the above configuration, even if a partially high-temperature site occurs in the plane direction, heat is conducted in the plane direction to suppress the occurrence of hot spots, thereby suppressing the occurrence of quasi-burning.

[0018] Furthermore, according to the heat insulating sheet according to the seventh aspect of the present invention, in addition to any of the above configurations, the intermediate layer can be composed of a papermaking sheet.

[0019] Furthermore, according to the heat insulation sheet according to the eighth aspect of the present invention, in addition to any of the above configurations, the intermediate layer can contain fibers or heat conductive fillers.

[0020] Furthermore, according to the heat insulation sheet according to the ninth aspect of the present invention, in addition to any of the above configurations, the intermediate layer can contain any one of graphite, boron nitride, and aluminum.

[0021] Furthermore, according to the heat insulation sheet according to the tenth aspect of the present invention, in addition to any of the above configurations, the ash area on the back surface when heated for 10 minutes according to the JIS L 1091 A-1 method (1999) test can be 500 mm 2 or less.

[0022] Furthermore, according to the heat insulation sheet according to the eleventh aspect of the present invention, in addition to any of the above configurations, the volume resistivity of the surface layer can be 10 10 or more. With the above configuration, the insulation property after combustion can be maintained.

[0023] Furthermore, according to the heat insulation sheet according to the twelfth aspect of the present invention, in addition to any of the above configurations, the surface layer can contain at least any one of fibers, fillers, and binders. With the above configuration, it is possible to avoid powder falling from the surface layer.

[0024] Furthermore, according to the heat insulation sheet according to the thirteenth aspect of the present invention, in addition to any of the above configurations, the adhesive layer that adheres the intermediate layer and the surface layer can be at least any one of an acrylic adhesive, a vinyl chloride adhesive, a vinyl acetate adhesive, and a hot melt.

[0025] Furthermore, according to the heat insulation sheet according to the fourteenth aspect of the present invention, in addition to any of the above configurations, the thickness can be 0.2 mm to 6.0 mm.

[0027] Furthermore, according to the present invention's 15According to the heat insulation sheet according to the form, in addition to any of the above configurations, the heat resistance temperature can be set to 300 to 600 °C.

[0028] Furthermore, according to the heat insulation sheet according to the 16 form of the present invention, in addition to any of the above configurations, it is a heat insulation sheet used for a power supply device in which a plurality of secondary battery cells are stacked, and includes an intermediate layer and surface layers respectively laminated on the surfaces of the intermediate layer. The thermal conductivity in the thickness direction of the surface layer is 0.50 W / m·K or less, the thermal conductivity in the thickness direction of the intermediate layer is 1.00 W / m·K or more, and the pore diameter of the surface layer is 50 μm or less and the compression ratio of the surface layer when compressed at 100 kPa is 10% or more can be achieved.

[0029] Furthermore, according to the 17 power supply device according to the form of the present invention, it can include any of the above heat insulation sheets and a plurality of secondary battery cells laminated with the heat insulation sheet interposed therebetween.

Brief Description of the Drawings

[0030]

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Best Mode for Carrying Out the Invention

[0031] Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the embodiments shown below are examples for embodying the technical idea of the present invention, and the present invention is not limited to the following. Also, this specification does not at all specify the members shown in the claims as the members of the embodiments. In particular, the dimensions, materials, shapes, relative arrangements, etc. of the constituent parts described in the embodiments are not intended to limit the scope of the present invention only to those, but are merely illustrative examples. Note that the sizes and positional relationships of the members shown in each drawing may be exaggerated for clarity of explanation. Furthermore, in the following description, the same names and reference numerals indicate the same or equivalent members, and detailed descriptions will be omitted as appropriate. Furthermore, each element constituting the present invention may be configured such that a plurality of elements are constituted by the same member and one member serves as a plurality of elements, or conversely, the function of one member may be shared by a plurality of members and realized. [Embodiment 1]

[0032] The heat insulating sheet according to the embodiment of the present invention can be appropriately used in applications where heat insulation is required. For example, it can be used as a heat insulating material for insulating refrigerators, freezers, etc., or a heat insulating sheet for building materials. Here, an example of using the heat insulating sheet as a spacer interposed between adjacent secondary battery cells in a power supply device in which a large number of secondary battery cells are stacked and connected in series or parallel will be described. Such a power supply device is used as a driving power supply for electric vehicles such as electric cars, hybrid cars, electric buses, trains, and electric carts, or as a backup power supply for factories and base stations, and further as a household storage battery.

[0033] The power supply device using the heat insulating sheet according to Embodiment 1 is shown in the perspective view of FIG. 1 and the vertical cross-sectional view of FIG. 2. The power supply device 100 shown in these figures includes a plurality of secondary battery cells 1 and a heat insulating sheet 10 interposed between the secondary battery cells 1. In this way, the secondary battery cells 1 and the heat insulating sheet 10 are alternately laminated to form a battery laminate. Further, side plates 2 are arranged on the side surfaces of the battery laminate as required. The side plate 2 is thermally coupled to the side surface of the secondary battery cell 1 and functions as a heat radiating plate that dissipates heat by heat conduction. (Heat insulating sheet 10)

[0034] A heat insulating sheet 10 is interposed between adjacent secondary battery cells 1. The heat insulating sheet 10 is called a spacer, a separator, etc., and is a member for preventing or suppressing thermal runaway by insulating between adjacent secondary battery cells 1. Further, the heat insulating sheet 10 can also function as a heat radiating member by thermally coupling its upper end, lower end, side surface, etc. to a heat radiating plate or the like. For example, heat radiating fins can be arranged above and below the battery laminate, and the upper and lower ends of the heat insulating sheet can be thermally coupled to the heat radiating fins respectively. (Secondary battery cell 1)

[0035] As the secondary battery cell 1, a lithium ion secondary battery can be preferably used. The secondary battery cell 1 has an exterior member made of a conductive member. In order to form a battery laminate by laminating a plurality of such secondary battery cells 1, in addition to heat insulation, insulation is also required. The heat insulating sheet 10 according to the present embodiment can be suitably used for a power supply device using a secondary battery cell using such a conductive exterior can by configuring the surface layer 12 with a sheet having insulating properties. Needless to say, the present invention can also be used for a secondary battery cell having an insulating exterior member, for example, a type called a pouch type or a laminate type having a plate-like outer shape. (Heat insulating sheet 10)

[0036] An enlarged cross-sectional view of the heat insulating sheet 10 is shown in FIG. 3. The heat insulating sheet 10 shown in this figure is composed of an intermediate layer 11 and surface layers 12 laminated on both sides so as to sandwich the intermediate layer 11.

[0037] The thermal conductivities of these intermediate layers 11 and the surface layer 12 are made different. Specifically, the thermal conductivity in the thickness direction of the surface layer 12 is set to 0.50 W / m·K or less, and the thermal conductivity in the thickness direction of the intermediate layer 11 is set to 1.00 W / m·K or more. By making the insulating sheet have such a multilayer structure in which each surface layer 12 is a heat-insulating layer with a suppressed thermal conductivity and the intermediate layer 11 interposed therebetween is a heat-dissipating layer with enhanced thermal conductivity, it is possible to realize the heat-insulating sheet 10 having excellent heat-insulating performance even with a thin surface layer 12.

[0038] Also, the in-plane thermal conductivity of the intermediate layer 11 is set to be 5 times or more that in the thickness direction. Thereby, while exerting the heat-insulating performance of the heat-insulating sheet 10 combined with the surface layer 12 having high heat-insulating performance, it is possible to effectively eliminate the occurrence of hot spots and prevent thermal runaway.

[0039] Conventional heat-insulating sheets were made of a material having high heat-insulating performance, in other words, low thermal conductivity, from the viewpoint of preventing thermal runaway. As a result, as shown in the schematic cross-sectional view of FIG. 4, even when a hot spot HS where a part of the secondary battery cell 1 becomes locally high temperature occurs, this high heat cannot be conducted and dissipated by the heat-insulating sheet 10X. As a result, the hot spot HS with no place to escape heat becomes even hotter, and eventually there is a possibility of combustion and thermal runaway. However, if the thermal conductivity of the heat-insulating sheet is increased, the heat-insulating performance cannot be exerted and the high temperature is propagated to the adjacent secondary battery cells, and there is a contradiction that thermal runaway cannot be suppressed and the original function of the heat-insulating sheet cannot be exerted.

[0040] In contrast, in the heat-insulating sheet 10 according to the present embodiment, the surface layer 12 is a heat-insulating layer with a suppressed thermal conductivity and is opposed to the secondary battery cell 1. As a result, the heat-insulating sheet 10 interposed between the adjacent secondary battery cells 1 can insulate the left and right secondary battery cells with high heat-insulating properties. Further, by using the surface layer 12 as an insulating layer, an unintentional short circuit between the secondary battery cells can be avoided. In particular, when using a secondary battery cell with a metal outer can, it can contribute to improving the insulation between the secondary battery cells and enhancing safety and reliability.

[0041] On the one hand, as shown in the schematic cross-sectional view of FIG. 5, even if a hot spot HS that locally becomes high temperature occurs in any of the secondary battery cells, the surface layer 12 (the right side in FIG. 5) facing this secondary battery cell exhibits heat insulation properties. However, for the heat that reaches the intermediate layer 11, by actively conducting heat in the plane direction, as a result, the heat is propagated and diffused over the entire surface of the surface layer 12, thereby stealing heat from the location where high temperature occurs and suppressing the expansion of the hot spot. In particular, by setting the in-plane thermal conductivity of the intermediate layer 11 to be 5 times or more that in the thickness direction, heat conduction in the plane direction is promoted, heat conduction to the back side is suppressed, and while preventing the situation where high heat is transmitted to the secondary battery cell located on the back side, heat is actively conducted in the plane direction to exert the effect of suppressing thermal runaway. Furthermore, as shown in FIG. 1, by thermally coupling the end face of the heat insulation sheet 10 to the side plate 2 or to a heat dissipation member, the heat dissipation performance can be further enhanced, and heat can be absorbed from the secondary battery cell to suppress thermal runaway.

[0042] On the other hand, due to the heat insulation effect of the surface layer 12 on the back side (the left side in FIG. 5), the propagation of high heat to other secondary battery cells can be blocked or suppressed, thereby reducing the risk of thermal runaway. In this way, by adopting a multilayer structure for the heat insulation sheet 10, adding a heat diffusion function to the intermediate layer 11 to suppress the hot spot HS, and adding a heat insulation function to the surface layer 12 to prevent thermal runaway to other secondary battery cells, the contradictory functions of heat dissipation performance and heat insulation performance, which were difficult to achieve conventionally, are made compatible, thereby enhancing safety. (Surface layer 12)

[0043] The surface layer 12 has a thermal conductivity in the thickness direction of 0.50 W / m·K or less, more preferably 0.01 W / m·K to 0.30 W / m·K, and even more preferably 0.02 W / m·K to 0.20 W / m·K. Such a surface layer 12 preferably contains any one of a fiber, a filler, and a binder in order to exhibit sufficient heat insulation performance.

[0044] Also, the pore diameter of the surface layer 12 is preferably 50 μm or less, more preferably 30 μm or less, and even more preferably 20 μm or less. Thereby, it is possible to suppress powder falling of the heat insulation sheet and eliminate the need for a process for preventing powder falling such as sealing the surface layer.

[0045] Also, the air permeability resistance of the surface layer 12 is preferably 3 to 5000 sec / 100 ml and more preferably 5 to 1000 sec / 100 ml using a Gurley standard densitometer conforming to JIS P 8117 (2009) test. If the air permeability resistance is smaller than this range, when fibers or powder fall off from the intermediate layer described later, their scattering cannot be prevented and a short circuit may occur. Also, if the air permeability resistance is larger than this range, the adhesive strength with the adhesive layer described later tends to decrease.

[0046] Also, the smoothness of the surface layer 12 is preferably such that the time until the pressure in the vacuum container changes from 50.7 kPa to 29.3 kPa is 15 to 150 sec using a smoothness tester conforming to JIS P 8119 (1998).

[0047] Furthermore, the surface layer 12 has a compression ratio of 10% or more when compressed at 100 kPa. Thereby, when the secondary battery cell expands or is vibrated, the stress on the intermediate layer 11 can be relaxed and the falling off of fibers or powder that inhibits insulation can be suppressed.

[0048] Here, the surface layer 12 of the heat insulation sheet 10 includes a fiber base material, a filler, and a binder. Preferably, natural pulp and inorganic fibers can be used as the fiber base material, silicate minerals as the filler, and a rubber composition as the binder. Specifically, the surface layer 12 according to Embodiment 1 includes hemp pulp and micro glass as the fiber base material, talc and sepiolite as the filler, and NBR as the binder.

[0049] The fiber base material (also referred to as the base material fiber) can be inorganic fibers such as glass fibers, carbon fibers, and ceramic fibers, or organic fibers such as aromatic polyamide fibers and polyethylene fibers. Here, natural pulp of organic fiber is used as the fiber base material. Hemp pulp can be preferably used as the natural pulp. The blending ratio of the hemp pulp is, for example, 5% by weight to 20% by weight, preferably 10% by weight.

[0050] Also, inorganic fibers may be included as the fiber base material. The blending ratio of the inorganic fibers is 5% by weight to 20% by weight, preferably 8% by weight to 15% by weight. In Embodiment 1, 12% by weight of micro glass is added as the inorganic fiber.

[0051] As the filler, an inorganic filler can be used. Examples of the inorganic filler include silicate minerals such as sepiolite, talc, kaolin, mica, and sericite, magnesium carbonate, calcium carbonate, hard clay, fired clay, barium sulfate, calcium silicate, wollastonite, sodium bicarbonate, synthetic silica such as white carbon and fused silica, natural silica such as diatomaceous earth, aluminum hydroxide, magnesium hydroxide, glass beads, etc. These can be used alone or in combination of a plurality. The addition of these inorganic fillers shows effects such as maintaining the shape and improving the heat insulation property in a high-temperature atmosphere. In Embodiment 1, talc with high flexibility is used. The blending amount of the filler is preferably 5% by weight to 65% by weight in the heat insulation sheet. In Embodiment 1, magnesium silicate is used as the filler, and 58% by weight of talc and 14% by weight of sepiolite are added.

[0052] As the binder, in addition to synthetic resins such as vinyl chloride resin, vinylidene chloride resin, acrylic resin, urethane resin, vinyl acetate resin, polyethylene resin, polystyrene resin, acrylonitrile-butadiene-styrene resin, acrylonitrile-styrene resin, fluororesin, silicone resin, epoxy resin, and phenol resin, acrylonitrile-butadiene rubber, hydrogenated acrylonitrile-butadiene rubber, acrylic rubber, acrylonitrile rubber, ethylene-propylene rubber, styrene-butadiene rubber, chloroprene rubber, butadiene rubber, butyl rubber, fluororubber, silicone rubber, fluorosilicone rubber, chlorosulfonated rubber, ethylene-vinyl acetate rubber, chlorinated polyethylene, chlorinated butyl rubber, epichlorohydrin rubber, nitrile isoprene rubber, natural rubber, and isoprene rubber can be used. Among them, acrylonitrile-butadiene rubber (NBR) is preferable in terms of high water resistance and oil resistance. These rubbers can be used alone or in combination of two or more. Also, for the purpose of higher water resistance and oil resistance, sizing agents such as alkyl ketene dimer and water repellents of fluorine-based or silicone-based can be used in combination. When using a rubber composition as the binder, the blending amount of the rubber is preferably 5.0 to 40% by weight in the heat insulation sheet. Here, 6.0% by weight of Nipol 1562, which is NBR, is added.

[0053] Furthermore, as additives, chemicals such as paper strengthening agents, fixing agents, and defoaming agents are added. Here, 0.5% by weight of WS4030 as a paper strengthening agent, 0.3% by weight of Cogum 15H as a paper strengthening agent, 1.9% by weight of sulfuric acid band as a fixing agent, and an appropriate amount of KM-70 as a defoaming agent are added.

[0054] The surface layer 12 has a thickness of 1 mm to 5.5 mm, preferably 0.15 mm to 2 mm, more preferably 0.2 mm to 1 mm. This surface layer 12 may be composed of a single layer, or may be composed of laminating a plurality of inorganic fiber layers such as a glass fiber layer or a ceramic fiber layer formed in layers. Also, inorganic fibers with a fiber length of 13 mm or more can be preferably used from the viewpoint of compression recovery. More preferably, they are long fibers that have not been cut, and even more preferably, they are 40 mm or more. (Intermediate layer 11)

[0055] The intermediate layer 11 has a thermal conductivity in the thickness direction of 1.00 W / m·K or more, preferably 2.00 W / m·K to 20.00 W / m·K, more preferably 2.50 W / m·K to 15.00 W / m·K. Alternatively, the thermal conductivity of the intermediate layer 11 in the thickness direction may be 3.00 W / m·K or less. Also, the thermal conductivity of the intermediate layer 11 in the plane direction is preferably 1000 W / m·K or less. With this configuration, when the power supply device 100 is provided with a gas discharge device such as an explosion-proof valve, before high heat propagates to another secondary battery cell through the outer can during the process of thermal runaway of any one of the secondary battery cells 1, it is possible to ensure a time lag for the thermal decomposition gas of the electrolyte to be discharged and the power supply device 100 to be cooled.

[0056] In order to exhibit sufficient thermal conductivity, such an intermediate layer 11 preferably contains organic fibers or a thermal conductive filler. As the organic fibers, any one or more of para-aramid fibers, para-aramid pulp, meta-aramid pulp, polyphenylene sulfide fibers, PET fibers, flame-retardant PET fibers, and flame-retardant rayon fibers can be used. Also, as the thermal conductive filler, magnesium oxide, aluminum oxide, boron nitride, aluminum nitride, aluminum, copper, graphite, carbon nanotubes, etc. can be used. Further, inorganic fibers may be included in the intermediate layer 11. As the inorganic fibers, carbon fibers, glass fibers, ceramic fibers, etc. can be used. Also, the intermediate sheet formed of a paper sheet may be subjected to a pressing process using a thermal calendar roll or the like. Thereby, the interior can be densified and the thermal conductivity can be increased.

[0057] Also, for the intermediate layer 11, film-like metals such as iron, aluminum, copper, silver, and gold can be used.

[0058] The intermediate layer 11 has a thickness of 0.02 mm to 0.5 mm, preferably 0.03 mm to 0.4 mm, more preferably 0.03 mm to 0.3 mm.

[0059] Also, the intermediate layer 11 preferably has an air permeability resistance of 3000 sec / ml or more as measured by a Gurley standard densitometer in accordance with JIS P 8117 (2009) test. This realizes an intermediate layer 11 having low powder loss and thermal diffusivity, and has the advantage that the manufacturing can be easily and inexpensively carried out without the need for sealing the layer having thermal diffusivity. (Adhesive layer)

[0060] The intermediate layer 11 and the surface layer 12 are adhered with an adhesive. An adhesive layer formed by curing the adhesive is interposed between the intermediate layer 11 and the surface layer 12. The adhesive is preferably a material having excellent heat resistance. As such an adhesive, acrylic adhesives, vinyl chloride adhesives, vinyl acetate adhesives, hot melts, etc. can be used. In addition to liquid and slurry forms, the adhesive can be a heat-sealing sheet formed by molding a hot melt adhesive into a non-woven fabric or a net shape.

[0061] Also, the total thickness of the heat insulating sheet 10 is 0.2 mm to 6.0 mm, preferably 0.2 mm to 4.0 mm, more preferably 0.3 mm to 2.0 mm.

[0062] Furthermore, the heat insulating sheet 10 has flexibility and flexibility. As a result, when the secondary battery cell 1 expands as shown in the cross-sectional view of FIG. 5, the heat insulating sheet 10 follows the deformation of the secondary battery cell 1 and maintains a close contact state, thereby avoiding a situation where the thermal conductivity decreases due to the formation of voids. In particular, many conventional heat insulating sheets are hard and have low followability to deformation. Therefore, voids are formed on the contact surface, and the thermal conductivity may decrease due to the heat insulating effect of the air layer. When the heat insulating sheet is intended to exhibit heat insulating performance for preventing thermal runaway, the hard heat insulating sheet is rather advantageous because the heat insulating performance is further improved by the air layer. On the other hand, like the heat insulating sheet 10 according to the present embodiment, in order for the surface layer 12 to exhibit heat dissipation performance, by using a heat insulating sheet 10 having flexibility and flexibility rather than such a hard material, a state with high thermal conductivity can be maintained and heat dissipation performance can be exhibited.

[0063] Moreover, by imparting flexibility and flexibility to the heat insulation sheet 10, it can be wound around a wound material such as a roll material, can be stored and transported in a roll shape, and the handleability is also improved. Here, in order to exhibit flexibility, for example, when a cylinder with an outer diameter of 110 mm is applied to one side of the heat insulation sheet 10 and bent by 90°, it can be ensured that no wrinkles or cracks occur.

[0064] Furthermore, it is desirable that the heat insulation sheet 10 has heat resistance and flame retardancy. Even when the secondary battery cell 1 becomes high temperature, by using a material that is difficult to deform or melt, it is possible to maintain the heat insulation performance. Preferably, the heat resistant temperature of the heat insulation sheet 10 is 300 to 600 °C. In the heat insulation sheet according to the present embodiment, the surface layer is composed of a fiber, a filler, and a binder, so that a high heat resistant temperature can be exhibited and the insulation property can be maintained even in a high temperature environment. Furthermore, the ash area on the back surface when heated for 10 minutes according to the JIS L 1091 A-1 method (1999) test is 2 Preferably suppressed to 500 mm or less.

[0065] In addition, in the heat insulation sheet 10 according to the present embodiment, it is preferable that the smoothness of the entire heat insulation sheet is 15 to 150 sec. Thereby, the advantage that the manufacturing can be easily and inexpensively performed without sealing the heat insulation sheet is obtained.

[0066] Also, the heat insulation sheet according to the present embodiment can have deformable flexibility. Preferably, it has flexibility such that it does not break even when wound around a paper tube with a curvature radius of 55 mm. Thereby, even if the object in contact with the heat insulation sheet is deformed such as expanding, it can follow the deformation and maintain an intimate state, and a situation where a void is formed and the heat conductivity is lowered can be avoided. (Manufacturing method of heat insulation sheet 10)

[0067] Here, the heat insulation sheet 10 can be manufactured in a roll-to-roll manner by sandwiching a heat-sealing sheet between, for example, a roll-shaped intermediate layer 11 and a surface layer 12 and passing it between two hot-pressing rolls for adhesion. Alternatively, a liquid adhesive may be applied to one or both sides of the intermediate layer 11 or the surface layer 12 and bonded together. In Examples 1 to 4 and Comparative Examples 1 to 2 described later, a heat-sealing sheet made of polyethylene was sandwiched between the intermediate layer 11 and the surface layer 12, and pressed at 50 kPa for 20 seconds with a hot press at 150 °C for adhesion.

[0068] In the above example, the configuration in which the heat insulation sheet 10 has a three-layer structure in which both sides of the intermediate layer 11 are each covered with a single-layer surface layer 12 has been described. However, the present invention is not limited to such a three-layer structure, and for example, a multilayer structure of four or more layers such as a plurality of surface layers or a plurality of intermediate layers can also be adopted. Alternatively, depending on the application, a two-layer structure in which a surface layer is provided only on one side of the intermediate layer may be used.

[0069] In the example of FIG. 1, the secondary battery cell 1 is in a vertically placed posture. Needless to say, the heat insulation sheet can be similarly applied to a power supply device in which the secondary battery cell is in a horizontally placed posture.

[0070] Furthermore, the heat insulation sheet 10 can be used not only for heat insulation between secondary battery cells but also for heat insulation between battery modules composed of a plurality of secondary battery cells. [Examples 1 to 4; Comparative Example 1]

[0071] Here, in order to confirm the flame retardancy of the heat insulation sheet according to the examples, samples of the heat insulation sheets according to Examples 1 to 4 were prepared and compared with samples of the heat insulation sheet according to Comparative Example 1. Table 1 shows the thickness and thermal conductivity of the intermediate layer and the surface layer used for each sample.

[0072] In Examples 1 to 4 and Comparative Example 1, the same sheet obtained by papermaking of natural pulp, micro glass, silicate mineral powder, and a rubber-based resin as a binder was used. For its preparation, first, the disintegrated natural pulp was prepared, and the micro glass and the silicate mineral powder were uniformly dispersed. A papermaking slurry obtained by adding a rubber-based resin thereto was papermade by the wet papermaking method to obtain a surface layer base sheet having a thickness of about 0.70 mm. The thermal conductivity (in the thickness direction) of this surface layer base sheet was 0.18 W / m·K, the thermal conductivity (in the plane direction) was 0.18 W / m·K, the smoothness was 46.8 sec, and the air permeability resistance was 30 sec / 100 ml. Using this surface layer base sheet, both sides of different intermediate layers were coated to prepare Examples 1 to 4 and Comparative Example 1. (Example 1)

[0073] As the intermediate layer of Example 1, a papermade sheet containing 90% graphite powder was used. Specifically, a papermaking slurry in which graphite powder and organic fibers were dispersed in water at a weight ratio of 90 to 10 was prepared, and the sheet obtained by the wet papermaking method was subjected to thermocompression processing to obtain an intermediate layer base sheet. Its thickness was 0.23 mm.

[0074] The surface layers were laminated on both sides of the obtained intermediate layer base sheet, and a polyethylene heat-sealing sheet was sandwiched between the surface layer and the intermediate layer, and pressure was applied at 50 kPa for 20 seconds at 150°C by hot pressing to bond them together, obtaining a heat insulation sheet according to Example 1. (Example 2)

[0075] As the intermediate layer of Example 2, a papermaking slurry in which graphite powder and organic fibers were dispersed in water at a weight ratio of 75 to 25 was prepared, and the sheet obtained by the wet papermaking method was subjected to thermocompression processing to obtain a surface layer base sheet 2. Its thickness was 0.07 mm. For the obtained intermediate layer base sheet, the surface layers were bonded to both sides in the same manner as in Example 1 to obtain a heat insulation sheet according to Example 2. (Example 3)

[0076] The intermediate layer of Example 3 was an aluminum film. Here, a Shimplate Aluminum TA200-300-02 manufactured by Iwata Seisakusho with a thickness of 0.2 mm was used as the intermediate layer base sheet. This intermediate layer base sheet was bonded to the surface layers on each side in the same manner as in Example 1 and the like to obtain a heat insulation sheet according to Example 3. (Example 4)

[0077] As the intermediate layer of Example 4, a thin aluminum film was used. Here, a Shimplate Aluminum TA200-300-01 manufactured by Iwata Seisakusho with a thickness of 0.1 mm was used as the intermediate layer base sheet. This intermediate layer base sheet was bonded to the surface layers on each side in the same manner as in Example 1 and the like to obtain a heat insulation sheet according to Example 4. (Comparative Example 1)

[0078] As the intermediate layer of Comparative Example 1, a paper sheet for heat insulation, which is the same as the surface layer, was used. Specifically, a paper-making slurry obtained by mixing raw materials at the same weight ratio as in Example 1 was paper-made by the wet paper-making method to obtain an intermediate layer base sheet with a thickness of about 0.3 mm. The obtained intermediate layer base sheet was bonded to the surface layers on both sides in the same manner as in Example 1 and the like to obtain a heat insulation sheet according to Comparative Example 1. Table 1 shows the thickness of the intermediate layer, the thickness of the entire heat insulation sheet, and the thermal conductivity (in the thickness direction and the plane direction) of the heat insulation sheets according to Examples 1 to 4 and Comparative Example 1.

[0079]

Table 1

[0080] Using these samples, first, a front and back surface temperature evaluation test of the samples was conducted. Specifically, as shown in the side view of FIG. 6A, a ceramic heater HT (MS-1000 manufactured by Sakaguchi Denki Co., Ltd.) was fixed to one side of the sample of the heat insulation sheet 10 with aluminum tape, and thermocouples T0, T1, T2, and T3 were attached to the upper surface of the heater HT and the opposite surface of the heat insulation sheet 10 in contact with the heater HT as shown in FIGS. 6B and 6C. In this state, the temperature difference between the front and back surfaces of the heat insulation sheet was measured from the difference between the heater temperature and the temperature of the back surface of the sheet when the heater HT was heated to 200 °C at an output of 9.5 W to 20 W. (Flexibility Test)

[0081] Furthermore, regarding the heat insulation sheets according to Examples 1 to 4 and Comparative Example 1, a test was conducted on flexibility. Specifically, the heat insulation sheet cut to 120 mm × 65 mm was pressed against the outer periphery of a paper tube with an outer diameter of 110 mm to check and evaluate whether damage such as wrinkles or cracks occurred. The evaluation was described in three levels as follows. 〇: No occurrence, △: Slight damage, ×: Serious damage that renders it unusable. These results are shown in Table 2.

[0082]

Table 2

[0083] As shown in Table 2, it was found that the heat insulation performance was improved by sandwiching the heat diffusion layer as shown in Examples 1 to 4 compared to Comparative Example 1 composed only of the heat insulation layer. The reason for this is presumed to be that by providing the heat insulation layer on both sides of the heat diffusion layer, heat concentration in a part of the heat insulation layer is avoided, and by being uniformly dispersed in the plane direction, the heat insulation performance is more easily exhibited throughout the heat insulation layer.

[0084] Also, it can be seen that Example 3 using aluminum in the intermediate layer has a larger temperature difference between the front and back compared to Examples 1 and 2 using graphite powder, in other words, the heat insulation effect is higher. Furthermore, although Example 4 is inferior to Example 3, it exhibits a high heat insulation effect. The aluminum in Examples 3 and 4 has the same thermal conductivity in the thickness direction and the plane direction and has no anisotropy. On the other hand, the heat diffusion layer using graphite powder in Examples 1 and 2 has a thermal conductivity in the plane direction 40 to 60 times higher than that in the thickness direction as shown in Table 1. Although the anisotropy of the thermal conductivity may seem to contribute nothing to the heat insulation performance at first glance, in the high temperature range, the thermal conductivity of graphite decreases, so actually there is a performance difference between Examples 3 and 4 greater than the values in Table 1, and it is considered that the heat diffusion rate in the plane direction also decreased. (Insulation Test)

[0085] Next, a test was conducted on the insulation property. Here, using the samples of Comparative Example 1 and Examples 1 and 2, the volume resistivity was tested in accordance with JIS K6911 (1995) "General Test Methods for Thermosetting Plastics" at room temperature with an applied voltage of 500 V. The AC withstand voltage was tested in accordance with JIS C21 10-1 "Solid Electrical Insulating Materials - Test Methods for Dielectric Strength - Part 1: Tests by Application of Commercial Frequency Alternating Voltage" and the DC withstand voltage was tested in accordance with JIS C2110-2 "Solid Electrical Insulating Materials - Test Methods for Dielectric Strength - Part 2: Tests by Application of Direct Voltage" at room temperature with an application time of 100 / 60 [V / sec] for each voltage. The results are shown in Table 3.

[0086]

Table 3

[0087] As shown in Table 3, although Examples 1 and 2 had an intermediate layer containing carbon powder which is a conductor, results comparable to those of Comparative Example 1 which is an insulator were obtained for both the volume resistivity and the breakdown voltage. (Measurement of Temperature Distribution)

[0088] ​Next, the temperature distribution was measured. Here, using the samples of Comparative Example 1 and Examples 1 to 4, a ceramic heater (MS-1000 manufactured by Sakaguchi Denki Co., Ltd.) was similarly attached to one side of the heat insulating sheet 10, heating was started at an output of 9.5 W (constant), and the temperature distribution of the entire sheet was measured with a thermographic camera for 10 minutes. Photographs taken with the thermographic camera are shown in FIGS. 7A to 11B. In these figures, FIG. 7A is a photograph of the sample of Example 1 taken from the heater side, and FIG. 7B is a photograph taken from the back side with a thermographic camera. Also, FIG. 8A is a photograph of the sample of Example 2 taken from the heater side, and FIG. 8B is a photograph taken from the back side with a thermographic camera. Further, FIG. 9A is the heater side of the sample of Example 3, FIG. 9B is the back side, FIG. 10A is the heater side of the sample of Example 4, FIG. 10B is the back side, FIG. 11A is the heater side of the sample of Comparative Example 1, and FIG. 11B is the back side, respectively, photographs taken. From these figures, in Comparative Example 1 composed only of the heat insulating layer, as shown in FIG. 11B, the back side is at a high temperature, whereas in Examples 1 to 4 in which both sides of the heat diffusion layer are covered with the heat insulating layer, it was confirmed that the temperature rise on the back side was suppressed in all cases. In particular, in Example 1 having a relatively large thickness, compared with Example 2 having a small thickness, it was confirmed that the temperature rise was suppressed and local temperature changes were also suppressed, and uniform heat dissipation in the plane direction was achieved. (600 °C Combustion Test)

[0089] Furthermore, in order to confirm the flame retardancy of the heat insulating sheet according to the examples, a combustion test was conducted. Here, combustion tests according to the JIS L 1091 A-1 method (1999) test (45° micro burner method) were conducted on the samples of Comparative Example 1 and Examples 1 to 4. However, the heating time was 10 minutes and the heating temperature was 600 °C.

[0090] For attachment to the jig, as in the 45° micro burner method, each sample was attached to the jig at an angle of 45° as shown in FIG. 12. Also, thermocouples TC1 and TC2 were attached to the flame contact part of the gas burner GB and its back surface, respectively. The flame of the gas burner GB was applied, and when the temperature of the thermocouple TC1 at the flame contact part reached 600 °C, the temperature of the thermocouple TC2 on the back surface was measured, and the temperature difference was calculated.

[0091] Furthermore, for each sample attached to the jig without attaching a thermocouple, the flame of the gas burner GB was applied for 10 minutes, the presence or absence of combustion was observed, the states of both sides of the sample after the test were photographed, and when a portion where the organic component burned and turned white and ashed was observed, the area was measured using the image processing software "leafareacounter_plus3_3". Using this image processing software, for the ashed area, as enclosed by the red line in Fig. 13A, the area where the organic component disappeared due to combustion and only the inorganic component remained, turning white and ashed, was measured. Similarly, for the carbonized area, as enclosed by the red line in Fig. 13B, the area that was blackened and charred including the ashed area was measured.

[0092] Photographs of each sample after the combustion test of Examples 1 to 4 and Comparative Example 1 are shown in Figs. 14A to 18B, respectively. In these figures, Fig. 14A shows the combustion surface of the sample of Example 1, Fig. 14B shows the photograph of the back surface, Fig. 15A shows the combustion surface of the sample of Example 2, Fig. 15B shows the photograph of the back surface, Fig. 16A shows the combustion surface of the sample of Example 3, Fig. 16B shows the photograph of the back surface, Fig. 17A shows the combustion surface of the sample of Example 4, Fig. 17B shows the photograph of the back surface, Fig. 18A shows the combustion surface of the sample of Comparative Example 1, and Fig. 18B shows the photograph of the back surface.

[0093] In Comparative Example 1 composed only of the heat insulation layer, as shown in Fig. 18A, a portion that seems to have been exposed to the flame on the combustion surface was confirmed to be in a white ashed state. This is presumably a state where the organic component burned and only the inorganic component remained in spots. Also on the back surface side, as shown in Fig. 18B, a similarly whitish ashed state was confirmed at the corresponding portion. It is considered to be a state where the organic component burned and only the inorganic component remained in spots.

[0094] On the other hand, in both Examples 1 and 2 coated with the thermal diffusion layer of graphite powder, no signs of combustion were confirmed on the combustion surface, and a slightly charred black soot-like appearance was confirmed as shown in Figs. 14A and 15A. Also on the back surface side, in Example 1, only a slight occurrence of wrinkles was confirmed as shown in Fig. 14B. This is presumably because the resin of the adhesive softened due to heat and wrinkles occurred.

[0095] Also in Example 2, as shown in FIG. 15B, although the occurrence of wrinkles was confirmed, the state of combustion was not confirmed. Thus, in Examples 1 and 2, it was confirmed that heat conduction to the back side was suppressed even when the front surface side was exposed to the flame.

[0096] In Examples 3 and 4, slightly charred portions were confirmed at the portions that seemed to be exposed to the flame on the combustion surface, but charring was not confirmed on the back surface, and it was confirmed that heat conduction to the back surface side was suppressed.

[0097] Table 4 shows a summary of these test results. Thus, in Examples 1 to 4, it was confirmed that the flame retardancy was superior to that of Comparative Example 1.

[0098] [Table 4] (Example 5)

[0099] As the surface layer of Example 5, papermaking was carried out in the same manner as in Example 1 except that the thickness was 0.30 mm, and a surface layer base material sheet was obtained. Using the obtained surface layer base material sheet, it was laminated on both sides of the same intermediate layer base material sheet as in Example 1, and bonded in the same manner as in Example 1 to obtain a heat insulating sheet according to Example 5. (Example 6)

[0100] To prepare the surface layer of Example 6, first, disintegrated natural pulp was prepared, and micro glass, chopped glass, synthetic silica, and diatomaceous earth were uniformly dispersed therein. A rubber-based resin was added thereto, and papermaking was carried out by the wet papermaking method to obtain a surface layer base material sheet having a thickness of about 0.80 mm. The thermal conductivity (in the thickness direction) of this sheet was 0.08 W / m·K, and the thermal conductivity (in the surface direction) was 0.08 W / m·K. Using the obtained surface layer base material sheet, it was laminated on both sides of the same intermediate layer base material sheet as in Example 1, and bonded in the same manner as in Example 1 to obtain a heat insulating sheet according to Example 6. (Comparative Example 2)

[0101] As the surface layer of Comparative Example 2, a PET film with a thickness of 0.03 mm was used, which was laminated on both sides of the intermediate layer base sheet in the same manner as in Example 1, and bonded together in the same manner as in Example 1 to obtain a heat insulation sheet according to Comparative Example 2. (Smoothness)

[0102] For each sample of Example 1, 5, 6 and Comparative Example 2, the smoothness was measured. Here, a digital Bekk smoothness tester (DB-2 type manufactured by Toyo Seiki Seisakusho Co., Ltd.) conforming to JIS P 8119 (1998) was used. The volume of the vacuum chamber was 380 mL. According to 8.e) of the above JIS standard, the test start pressure was 50.7 KPa and the test end pressure was 29.3 KPa. According to the above JIS standard, the standard test start pressure is 50.7 KPa and the test end pressure is 48.0 KPa. However, under these conditions, the measurement time was shorter than 15 seconds, so the test was carried out by changing the test end pressure to a lower value. The results are shown in Table 4. In addition, since Comparative Example 2 was extremely smooth, the measurement was stopped when the measured value reached 3000 sec. (Bubble point test and pore diameter)

[0103] In Example 1, 5, 6 and Comparative Example 2, the bubble point value of the surface layer base sheet before bonding to the intermediate layer was measured according to JIS K 3832 (1990), and the pore diameter was calculated. Specifically, a sample of the surface layer cut into 4 cm × 4 cm was immersed in a test liquid composed of Fluorinert FC-40 with a surface tension of 16 mN / m, and the sample completely filled with the test liquid was attached to a palm porometer CFP-1100AE (Porouse Materials Inc.) for measurement. The pore diameter d [μm] was calculated from the obtained bubble point value by the following formula. The results are shown in Table 4. In addition, in Comparative Example 2, the pore diameter was extremely small and was below the measurement lower limit and could not be measured. d = (2.86 × γ) / P (γ: surface tension of the test liquid, P: bubble point value [kPa]) (Air permeability resistance test)

[0104] Similarly, in Examples 1, 5, and 6 and Comparative Example 2, the air permeability resistance of the surface layer base material sheet before being laminated with the intermediate layer was measured using a Gurley standard densitometer in accordance with the JIS P 8117 (2009) test. The results are shown in Table 4. Note that in Comparative Example 2, the air permeability resistance was extremely high, and the measurement was terminated when the measured value reached 6000 sec / ml. (Compression recovery rate) Similarly, for Examples 1, 5, and 6 and Comparative Example 2, the compression ratio of the surface layer base material sheet when the pressure was 100 kPa before being laminated with the intermediate layer was measured. An Instron universal material testing machine model 5985 was used as the measuring instrument. With a load area of 50 mmφ, compression was performed at a speed of 0.1 mm / min, the displacement when the pressure reached 100 kPa was measured, and the percentage with respect to the initial thickness of the sheet was calculated. The results are shown in Table 4. (600°C insulation retention test) Samples of Examples 1, 5, and 6 and Comparative Example 2 were fixed in accordance with the 45° micro burner method, a thermocouple TC1 was attached to the flame contact part, the flame of the gas burner GB was applied, heated for 10 minutes so that the thermocouple TC1 at the flame contact part reached 600°C, and then the burner was extinguished. The sample was allowed to cool while still attached to the jig, the thermocouple TC1 was removed, electrodes of a digital tester TST-KJ830 (manufactured by Ohm Electric Co., Ltd.) were applied to the flame contact part and the back surface, and it was confirmed whether conduction occurred. The results are shown in Table 5. (○: No conduction, ×: Conduction occurred)

[0105]

Table 5

[0106] As shown in these results, in all of Examples 1, 5, and 6, the insulation property was maintained even after heating at 600°C, and heat resistance was confirmed. Also, it can be said that the pore diameter of the examples is small and it is in a layered form where powder does not fall off. In particular, in an environment exposed to vibrations such as in a power supply device, the property of not falling off powder is important, and it was confirmed that by using the heat insulation layer according to each example as the surface layer, a heat insulation sheet can be used more stably and with high reliability.

Industrial applicability

[0107] The heat insulation sheet of the present invention can be suitably used for heat insulation spacers interposed between secondary battery cells, buffer sheets interposed between explosion-proof valves and gas ducts, or heat insulation materials for protecting drive circuits such as ECUs. Further, a power supply device using the heat insulation sheet can be suitably used for mobile electronic devices, power equipment driven by a battery-driven motor, electric vehicles such as electric cars and hybrid cars, electric two-wheel vehicles such as assist bicycles and electric scooters, electric golf carts and drones, power storage systems, and the like.

Explanation of Signs

[0108] 100…Power supply device 1…Secondary battery cell 2…Side plate 10, 10X…Heat insulation sheet 11…Intermediate layer 12…Surface layer 92…Thermal conduction sheet 93…First insulating sheet 94…Second insulating sheet 95…Heat insulation layer HS…Hot spot HT…Heater T0, T1, T2, T3, TC1, TC2…Thermocouple GB…Gas burner

Claims

1. An intermediate layer, a surface layer laminated on the surface of the intermediate layer, comprising: wherein the thermal conductivity of the surface layer in the thickness direction is 0.50 W / m·K or less, the thermal conductivity of the intermediate layer in the thickness direction is 1.00 W / m·K or more, the pore diameter of the surface layer is 50 μm or less, and the heat insulation sheet is formed such that the compression ratio when the surface layer is compressed at 100 kPa is 10% or more.

2. An intermediate layer, a surface layer laminated on the surface of the intermediate layer, comprising: wherein the thermal conductivity of the surface layer in the thickness direction is 0.50 W / m·K or less, the thermal conductivity of the intermediate layer in the thickness direction is 1.00 W / m·K or more, and the air permeability resistance of the surface layer is 3 to 5000 sec / 100 mL as measured by a Gurley standard densometer in accordance with JIS P 8117 (2009) test.

3. The heat insulation sheet according to Claim 1 or 2, wherein the surface layer is laminated on both surfaces of the intermediate layer.

4. The heat insulation sheet according to any one of Claims 1 to 3, wherein the thermal conductivity of the intermediate layer in the plane direction is 1000 W / m·K or less.

5. The heat insulation sheet according to any one of Claims 1 to 4, wherein the thermal conductivity of the intermediate layer in the thickness direction is 3.00 W / m·K or less.

6. The heat insulation sheet according to any one of Claims 1 to 5, wherein the thermal conductivity of the intermediate layer in the plane direction is 5 times or more the thermal conductivity in the thickness direction.

7. The heat insulation sheet according to any one of Claims 1 to 6, wherein the intermediate layer is composed of a paper sheet.

8. The heat insulation sheet according to any one of Claims 1 to 7, wherein the intermediate layer contains fibers or a thermal conductive filler.

9. The heat insulation sheet according to any one of Claims 1 to 6, wherein the intermediate layer contains any one of graphite, boron nitride, and aluminum.

10. The heat insulation sheet according to any one of Claims 1 to 9, The heat insulation sheet in which the ashing area of the back surface when heated for 10 minutes according to the JIS L 1091 A-1 method (1999) test is 500 mm 2 or less.

11. The heat insulation sheet according to any one of Claims 1 to 10, The volume resistivity of the surface layer is 10 10 or more. The heat insulation sheet

12. The heat insulation sheet according to any one of Claims 1 to 11, wherein the surface layer contains at least one of fibers, fillers, and binders.

13. The heat insulation sheet according to any one of Claims 1 to 12, A heat insulation sheet in which an adhesive layer that bonds the intermediate layer and the surface layer is at least one of an acrylic adhesive, a vinyl chloride adhesive, a vinyl acetate adhesive, and a hot melt.

14. A heat insulation sheet according to any one of Claims 1 to 13, The heat insulation sheet having a thickness of 0.2 mm to 6.0 mm.

15. A heat insulation sheet according to any one of Claims 1 to 14, The heat insulation sheet having a heat resistant temperature of 300 to 600 °C.

16. A heat insulation sheet used for a power supply device in which a plurality of secondary battery cells are stacked, An intermediate layer, Surface layers respectively laminated on the surfaces of the intermediate layer, Comprising, The heat conductivity in the thickness direction of the surface layer is 0.50 W / m·K or less, The heat conductivity in the thickness direction of the intermediate layer is 1.00 W / m·K or more, The pore diameter of the surface layer is 50 μm or less, A heat insulation sheet in which the compression ratio when the surface layer is compressed at 100 kPa is 10% or more.

17. A heat insulation sheet according to Claim 16, A plurality of secondary battery cells laminated with the heat insulation sheet interposed therebetween, A power supply device comprising.

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