Battery housing

Abstract

To provide a battery housing made of fiber-reinforced resin that offers superior flame resistance, enabling delaying the spread of fire to automotive interior components in the event of battery thermal runaway and resulting flames. [Solution] A battery housing made of fiber-reinforced resin, wherein the fibers include at least inorganic fibers with a melting temperature exceeding 1000°C.

Description

[Technical Field]

[0001] This invention relates to a battery housing. [Background technology]

[0002] In all types of transportation machinery that use motors, weight reduction is a challenge in order to improve energy efficiency. Focusing on battery housings, metal materials have traditionally been used, and their weight has been a problem. Aluminum is a lightweight metal, but because of its low melting point, it is easily penetrated by flames generated when a battery overheats, and oxygen is supplied through the hole, causing explosive combustion, making it unsuitable for use. While resin could be considered as another lightweight material, it lacked sufficient flame resistance and rigidity for use as a battery housing, making its application difficult.

[0003] To address the above problems, for example, Patent Document 1 proposes a vehicle battery case made by molding a carbon fiber-reinforced polypropylene resin composition, which is obtained by blending 8 to 70 parts by weight of carbon fiber and 0.6 to 37.5 parts by weight of flame retardant with 100 parts by weight of polypropylene resin, characterized in that the weight-average fiber length of the carbon fibers in the molded product is 0.5 mm or more and less than 3 mm. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2014-62189 [Overview of the project] [Problems that the invention aims to solve]

[0005] To extend the driving range of electric vehicles, the energy density of battery modules tends to increase. Therefore, even reinforced resin battery housings require greater flame resistance. The present invention aims to provide a battery housing made of fiber-reinforced resin that offers superior flame resistance, enabling delaying the spread of fire to automotive interior components in the event of thermal runaway of a battery and the generation of flames under such circumstances. [Means for solving the problem]

[0006] In order to solve the above problems, the inventors conducted extensive research and found that a battery housing made of fiber-reinforced resin containing at least inorganic fibers with a melting or burning temperature exceeding 1000°C in an atmospheric environment can solve the above problems. Based on these findings, the inventors completed the present invention. In other words, the present invention provides the following [1] to

[12] . [1] A battery housing made of fiber-reinforced resin, wherein the fibers include a high heat-resistant fiber A having a melting or burning temperature in an atmospheric environment of more than 1000°C, and an inorganic fiber B having a lower melting or burning temperature than the high heat-resistant fiber A, and the mass ratio of the inorganic fiber B to the high heat-resistant fiber A (B / A) is greater than 1 and in the range of 8. [2] The battery housing according to [1], wherein the mass ratio (B / A) of inorganic fiber B to high heat-resistant fiber A is in the range of 2 to 6. [3] The battery housing according to [1] or [2] above, wherein the average fiber diameter of the high heat-resistant fiber A is 3 to 25 μm and the average fiber length is 5 mm or more. [4] The battery housing according to any one of [1] to [3] above, wherein the average fiber length of the inorganic fiber B is longer than the average fiber length of the high heat-resistant fiber A. [5] A battery housing according to any one of [1] to [4] above, wherein the content of the high heat-resistant fiber A is 1 part by mass or more per 100 parts by mass of the fiber-reinforced resin. [6] The battery housing according to any one of [1] to [5] above, wherein the inorganic fiber B contains glass fiber. [7] The battery housing according to any one of [1] to [6] above, wherein the high heat-resistant fiber A is an alumina fiber. [8] A battery housing according to any one of [1] to [7] above, which is made by molding a stampable sheet made of the fiber-reinforced resin. [9] A structure having a battery housing and battery cells as described in any of [1] to [8] above.

[10] The structure according to [9] above, wherein the mat layer of inorganic fiber B in the battery housing is arranged on the battery cell side.

[11] The structure described in [9] or

[10] above, for use in an electric vehicle.

[12] An electric mobility device having the structure described in any of [9] to

[11] above. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a battery housing with superior flame resistance that can delay the spread of fire to automotive interior materials when a battery experiences thermal runaway and generates flames. [Brief explanation of the drawing]

[0008] [Figure 1] This is a conceptual diagram illustrating the battery housing. [Figure 2] This is a schematic diagram showing the stampable sheet of Example 1.

[0009] The following describes embodiments of the present invention in detail, but the following description is merely an example of an embodiment of the present invention, and the present invention is not limited in any way to these embodiments.

[0010] [Battery Housing] Figure 1 is a conceptual diagram showing a structure such as a battery, including a battery housing. The structure 10 of the battery, for example, includes a battery module 11 which is an assembly of battery cells (individual batteries), a battery pack 12 which is an assembly of battery modules, and a battery housing 13 for housing battery components such as the battery pack. The battery housing of the present invention is made of a fiber-reinforced resin, and as the fibers, it contains a high heat-resistant fiber A having a melting temperature or ablation temperature exceeding 1000°C in an air atmosphere, and an inorganic fiber B having a lower melting temperature or ablation temperature than the high heat-resistant fiber A (hereinafter, may be simply referred to as "inorganic fiber B").

[0011] <Fiber> As the fibers in the fiber-reinforced resin according to the present invention, organic fibers or inorganic fibers may be used, but inorganic fibers are preferred from the viewpoint of heat resistance. Examples include glass fibers, rock wool, basalt fibers, alumina fibers, silica alumina fibers, potassium titanate fibers, calcium silicate (wollastonite) fibers, alkaline earth silicate fibers (biodegradable), etc. These inorganic fibers may be used alone or in combination of two or more. In the present invention, it is characterized in that as the fibers, it contains a high heat-resistant fiber A having a melting temperature or ablation temperature exceeding 1000°C in an air atmosphere. Examples of the high heat-resistant fiber include alumina fibers, potassium titanate fibers, silica alumina fibers, alkaline earth silicate fibers (biodegradable), basalt fibers, etc. Among these, alumina fibers are particularly preferred. The high heat-resistant fibers can be used alone or in combination of two or more. In addition, as the fibers, in addition to the above-mentioned high heat-resistant fiber A, it contains an inorganic fiber B having a lower melting temperature or ablation temperature than the high heat-resistant fiber A. By including two or more kinds of fibers having different melting temperatures or ablation temperatures in an air atmosphere, it is possible to prevent the high heat-resistant fiber A from breaking and prevent the deterioration of the function of the high heat-resistant fiber A.

[0012] The content of the high heat-resistant fiber A is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more with respect to 100 parts by mass of the fiber-reinforced resin. Regarding the upper limit, 20 parts by mass or less is preferred, 15 parts by mass or less is more preferred, and 10 parts by mass or less is even more preferred. When it is above the above lower limit value, sufficient heat shielding properties and rigidity can be obtained, and when it is below the above upper limit value, processability is ensured.

[0013] As the fiber of the present invention, it is essential to contain the high heat-resistant fiber A as described above, and it is also essential to contain an inorganic fiber B having a melting temperature or a burnout temperature lower than that of the high heat-resistant fiber A. By mixing the inorganic fiber B with the high heat-resistant fiber A, it is possible to prevent the high heat-resistant fiber A from breaking and to prevent the deterioration of the function of the high heat-resistant fiber A. From the above viewpoints, glass fiber is preferable as the inorganic fiber B, and it is particularly preferable that the fiber in the present invention contains alumina fiber and glass fiber. When containing the high heat-resistant fiber A (for example, alumina fiber) and the inorganic fiber B (for example, glass fiber), the mass ratio thereof (inorganic fiber B / high heat-resistant fiber A) with respect to the high heat-resistant fiber A is required to be in the range of more than 1 to 8, and preferably in the range of 2 to 6. In addition, the high heat-resistant fiber A such as alumina fiber and the inorganic fiber B such as glass fiber may be contained in the fiber reinforced resin, or the mat of the high heat-resistant fiber A such as alumina fiber and the mat of the inorganic fiber B such as glass fiber, which will be described in detail later, may be laminated and impregnated with resin to form a sheet-like material.

[0014] Note that the fiber used in the present invention may be used in combination with a sizing agent or a surface treatment agent. Examples of such a sizing agent or a surface treatment agent include compounds having functional groups such as epoxy-based compounds, silane-based compounds, and titanate-based compounds.

[0015] The fiber of the present invention contains the high heat-resistant fiber A and the inorganic fiber B, and it is preferable that the average fiber diameter of at least one kind of fiber is 3 to 25 μm, and the average fiber length is preferably 5 mm or more. In particular, it is preferable that the average fiber diameter and the average fiber length of the high heat-resistant fiber A are within the above ranges. In addition, the average fiber length of the inorganic fiber B is preferably longer than the average fiber length of the high heat-resistant fiber A. By taking such a mode, it is possible to more effectively prevent the high heat-resistant fiber A from breaking and to prevent the deterioration of the function of the high heat-resistant fiber A. Furthermore, fiber diameter can be measured using an optical microscope, and the average fiber diameter can be obtained, for example, by measuring the fiber diameter of 10 randomly selected fibers and calculating the average value. In addition, fiber length can be measured using a ruler, calipers, etc., from an image magnified with a microscope, etc., as needed, and the average fiber length can be obtained, for example, by measuring the fiber length of 10 randomly selected fibers and calculating the average value.

[0016] The fiber content in the fiber-reinforced resin of the present invention is preferably 3 to 60% by mass. When the fiber content is 3% by mass or more, the strength, rigidity, and impact resistance of the battery housing can be ensured. On the other hand, when the fiber content is 60% by mass or less, the manufacturing and processing of the battery housing can be easily performed. Furthermore, when the fiber content is 60% by mass or less, the specific gravity becomes lighter, which has the advantage of a greater weight reduction effect as a metal substitute. From the above perspective, the fiber content in the fiber-reinforced resin is more preferably 10 to 50% by mass, and even more preferably 30 to 45% by mass. In this context, "fibers" encompass both the high-heat-resistant fiber A and inorganic fiber B mentioned above.

[0017] <Thermoplastic resin> The resin constituting the fiber-reinforced resin of the present invention is not particularly limited, but can be a thermoplastic resin. Examples of thermoplastic resins are not particularly limited and include polyethylene, polyolefin resins such as polypropylene, polyvinyl chloride, polystyrene, polyvinyl acetate, polyurethane, and the like. Of these, polyolefin resins are preferred in terms of resin properties, versatility, cost, etc., and polypropylene resins are particularly preferred.

[0018] (Polypropylene resin) Examples of polypropylene-based resins include propylene homopolymers or propylene-α-olefin copolymers. Here, the propylene-α-olefin copolymer may be either a random copolymer or a block copolymer.

[0019] <<Thermoplastic resin content>> The thermoplastic resin content in the battery housing of the present invention is preferably 20 to 80% by mass. When the thermoplastic resin content is 20% by mass or more, the moldability is sufficient, and the molding of the battery housing becomes easy. On the other hand, when the content is 80% by mass or less, the inorganic fiber content is sufficient, and sufficient flame resistance can be obtained. From the above viewpoint, the thermoplastic resin content in the battery housing is preferably 35 to 70% by mass, and more preferably 40 to 60% by mass.

[0020] <Optional addition ingredients> In addition to the above components, the battery housing of the present invention may contain any additive components to further enhance the effects of the invention or to impart other effects, as long as they do not significantly impair the effects of the present invention. Specifically, examples include colorants such as pigments, light stabilizers such as hindered amines, ultraviolet absorbers such as benzotriazoles, nucleating agents such as sorbitols, antioxidants such as phenols and phosphorus, antistatic agents such as nonionic surfactants, neutralizing agents such as inorganic compounds, antibacterial and antifungal agents such as thiazoles, flame retardants such as halogen compounds, plasticizers, dispersants such as organometallic salts, lubricants such as fatty acid amides, metal deactivators such as nitrogen compounds, polyolefin resins other than the aforementioned polypropylene resins, thermoplastic resins such as polyamide resins and polyester resins, elastomers (rubber components) such as olefin elastomers and styrene elastomers. Two or more of these optional additives may be used in combination.

[0021] As colorants, inorganic and organic pigments, for example, are effective in imparting and improving the colored appearance, aesthetics, texture, commercial value, weather resistance, and durability of polypropylene resin compositions and their molded articles. Specific examples of inorganic pigments include carbon black such as furnace carbon and Ketjencarbon; titanium dioxide; iron oxide (such as red iron oxide); chromic acid (such as yellow lead); molybdic acid; selenides sulfides; and ferrocyanides. Organic pigments include azo pigments such as sparingly soluble azo lakes, soluble azo lakes, insoluble azo chelates, condensing azo chelates, and other azo chelates; phthalocyanine pigments such as phthalocyanine blue and phthalocyanine green; slene pigments such as anthraquinone, perinone, perylene, and thioindigo; dye lakes; quinacridone-based pigments; dioxazine-based pigments; and isoindolinone-based pigments. In addition, aluminum flakes and pearl pigments can be included to create metallic or pearlescent finishes. Dyes can also be included.

[0022] For example, hindered amine compounds, benzotriazole compounds, benzophenone compounds, and salicylate compounds are effective as light stabilizers and ultraviolet absorbers in providing and improving the weather resistance and durability of polypropylene resin compositions and their molded articles, and are also effective in further improving weather resistance and discoloration. Specific examples of hindered amine compounds include the condensate of dimethyl succinate and 1-(2-hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethylpiperidine; poly[[6-(1,1,3,3-tetramethylbutyl)imino-1,3,5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4-piperidyl)imino]hexamethylene[(2,2,6,6-tetramethyl-4-piperidyl)imino]]; tetrakis(2,2,6,6-tetramethyl-4-piperidyl)1,2,3,4-butanetetracarboxylate; tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl)1,2,3,4-butanetetracarboxylate; bis(1,2,2,6,6-pentame Examples of benzotriazoles include 2-(2'-hydroxy-3',5'-di-t-butylphenyl)-5-chlorobenzotriazole and 2-(2'-hydroxy-3'-t-butyl-5'-methylphenyl)-5-chlorobenzotriazole. Examples of benzophenones include 2-hydroxy-4-methoxybenzophenone and 2-hydroxy-4-n-octoxybenzophenone. Examples of salicylates include 4-t-butylphenyl salicylate and 2,4-di-t-butylphenyl 3',5'-di-t-butyl-4'-hydroxybenzoate. In this context, the method of using the light stabilizer and the ultraviolet absorber in combination is highly preferable due to its significant improvement in weather resistance, durability, and resistance to weather-induced discoloration.

[0023] For example, antioxidants such as phenolic, phosphorus-based, and sulfur-based antioxidants are effective in imparting and improving the heat resistance, processing stability, and heat aging resistance of polypropylene resin compositions and their molded articles. Furthermore, antistatic agents such as nonionic and cationic agents are effective in imparting and improving the antistatic properties of polypropylene resin compositions and their molded articles.

[0024] Examples of olefin-based elastomers include ethylene-α-olefin copolymer elastomers such as ethylene-propylene copolymer elastomer (EPR), ethylene-butene copolymer elastomer (EBR), ethylene-hexene copolymer elastomer (EHR), and ethylene-octene copolymer elastomer (EOR); ethylene-α-olefin-diene terpolymer elastomers such as ethylene-propylene-ethylidene norbornene copolymer, ethylene-propylene-butadiene copolymer, and ethylene-propylene-isoprene copolymer; and styrene-butadiene-styrene triblock copolymer elastomer (SBS). Examples of styrene-based elastomers include styrene-isoprene-styrene triblock copolymer elastomer (SIS), styrene-ethylene-butylene copolymer elastomer (SEB), styrene-ethylene-propylene copolymer elastomer (SEP), styrene-ethylene-butylene-styrene copolymer elastomer (SEBS), styrene-ethylene-butylene-ethylene copolymer elastomer (SEBC), hydrogenated styrene-butadiene elastomer (HSBR), styrene-ethylene-propylene-styrene copolymer elastomer (SEPS), styrene-ethylene-ethylene-propylene-styrene copolymer elastomer (SEEPS), styrene-butadiene-butylene-styrene copolymer elastomer (SBBS), partially hydrogenated styrene-isoprene-styrene copolymer elastomer, partially hydrogenated styrene-isoprene-butadiene-styrene copolymer elastomer, and hydrogenated polymer elastomers such as ethylene-ethylene-butylene-ethylene copolymer elastomer (CEBC). In particular, the use of ethylene-octene copolymer elastomer (EOR) and / or ethylene-butene copolymer elastomer (EBR) is preferred because it is easier to impart appropriate flexibility and other properties to the polypropylene resin composition and molded articles thereof of the present invention, and they tend to have excellent impact resistance.

[0025] <Battery housing structure> The thickness of the battery housing of the present invention is not particularly limited, but is preferably 0.5 mm or more, more preferably 1.0 mm or more, and even more preferably 2.0 mm or more. A thickness above the lower limit is preferable in terms of moldability, mechanical strength, and flame resistance. Furthermore, the thickness of the battery housing is preferably 10 mm or less, more preferably 8 mm or less, and particularly preferably 6 mm or less. A thickness below the upper limit is preferable in terms of adaptability to the size of the space in which it is installed, as well as weight reduction and moldability.

[0026] <Battery housing manufacturing method> Various methods can be used to manufacture the battery housing of the present invention, but press molding is preferred from the viewpoint of productivity. When press molding, it is preferable to prepare stampable sheets made of the fiber-reinforced resin of the present invention, stack multiple sheets, and press mold them. It is preferable that the stampable sheet containing the high heat-resistant fibers is sandwiched on both sides by other stampable sheets so that the high heat-resistant fibers can easily flow throughout the sheet. When stacking multiple stampable sheets containing the high heat-resistant fibers, it is preferable to stack them as close to the center as possible.

[0027] (Manufacturing of stampable sheets) Stampable sheets are preferably manufactured by impregnating a mat made of fibers with a thermoplastic resin composition. Methods of impregnation include applying the thermoplastic resin composition to a fiber mat such as an inorganic fiber mat, or preparing a sheet of the thermoplastic resin composition, laminating the sheet onto the fiber mat, and then heating and melting it to impregnate the mat. In the present invention, from the viewpoint of surface smoothness of the stampable sheet, a method of laminating a thermoplastic resin sheet onto a fiber mat, heating, and melting is preferred. In particular, the fiber mat is laminated so that it is between two thermoplastic resin sheets, and then the laminate is heated and pressurized, and then cooled and solidified to obtain the stampable sheet.

[0028] <<Thermoplastic resin composition>> As the thermoplastic resin composition, it contains a thermoplastic resin, optional additives, etc., excluding the above-mentioned fibers. As the manufacturing method, a conventionally known method can be used, and it can be manufactured by blending the above components, mixing, and melt-kneading. Mixing is performed using a mixer such as a tumbler, V blender, ribbon blender, etc., and melt-kneading is performed using equipment such as a single-screw extruder, twin-screw extruder, Banbury mixer, roll mixer, Brabender plastograph, kneader, etc., and is melt-kneaded and granulated.

[0029] (Fiber mat) The form of the fiber used in the method for manufacturing a stampable sheet is not particularly limited, and various forms can be used, but those formed in a mat shape or sheet shape are preferred. More specifically, in the present invention, it is preferable to use a mat formed of high heat-resistant fibers typified by alumina fibers (hereinafter referred to as "high heat-resistant fiber mat"), and in addition to this, it is preferable to use a mat formed of glass fibers (hereinafter referred to as "glass fiber mat").

[0030] The basis weight (mass per unit area) of the fiber mat is not particularly limited and is appropriately determined according to the application, but preferably 300 g / m 2 More preferably 500 g / m 2 Even more preferably 700 g / m 2 Even more preferably 900 g / m 2 Particularly preferably 1000 g / m 2 Or more. Also, the basis weight of the fiber mat is not particularly limited, but preferably 5000 g / m 2 More preferably 4500 g / m 2 Even more preferably 4000 g / m 2 Particularly preferably 3500 g / m 2 Or less.

[0031] The thickness of the fiber mat according to the present invention is not particularly limited, but is preferably 4 mm or more, more preferably 5 mm or more, and even more preferably 6 mm or more. Furthermore, the thickness of the fiber mat is preferably 40 mm or less, even more preferably 35 mm or less, and particularly preferably 30 mm or less.

[0032] The basis weight and thickness per unit area of ​​the fiber mat can be set to the above range by adjusting the amount of fiber per unit area when stacking the fiber aggregates constituting the fiber mat using a folding device. Furthermore, the fiber mat in the present invention may be a single structure or a structure in which multiple fiber mats are bonded together, but a single structure is preferable in terms of handling properties and peel strength at the adhesive interface.

[0033] (Glass fiber mat) Examples of glass fiber mats used in the present invention include felts and blankets processed from short-fiber glass cotton, chopped strand mats processed from continuous glass fibers, swirl mats of continuous glass fibers, and unidirectional aligned mats. Among these, using a glass fiber mat made by needle-punching a swirl mat of continuous glass fibers is particularly preferable because it provides excellent strength and impact resistance for the stampable sheet.

[0034] (High heat-resistant fiber mat) The heat-resistant fiber mat according to the present invention is a mat composed of heat-resistant fibers and subjected to a needling process. Therefore, the mat has needle marks formed by the needling process. That is, when a needling process is performed in which a barbed needle is inserted into a heat-resistant fiber aggregate, at least some of the fibers are extended in the substantially thickness direction by the needle at the locations where the needle is inserted. As a result, needle marks are formed on the surface of the heat-resistant fiber mat. On the other hand, bundles of heat-resistant fibers formed in the substantially thickness direction within the needling-treated heat-resistant fiber mat are called warp threads.

[0035] Among the warp threads present within the high-temperature resistant fiber mat, those with a specific diameter and length are defined as effective warp threads. Specifically, when a peel test is performed, among all warp threads protruding from both peel surfaces (one peel surface and the other peel surface) per unit area (50 mm x 50 mm), those with a diameter of 100 μm or more and a protruding length of 2 mm or more are defined as effective warp threads. Needling is performed to adjust the bulk density, peel strength, surface pressure (surface pressure after high-temperature cycling), and resilience (surface pressure retention rate after high-temperature cycling) of the alumina fiber mat by forming warp threads. In other words, effective warp threads refer to those warp threads present in the approximate thickness direction within the high-temperature resistant fiber mat that have a diameter and length capable of functioning as warp threads. Furthermore, the volume of effective warp threads refers to the volume of the region protruding from the peel surface. In this invention, it is preferable to use an alumina fiber mat.

[0036] In a method of laminating a thermoplastic resin sheet onto a fiber mat and then heating and melting it, appropriate conditions should be selected according to the type of thermoplastic resin. The following describes suitable conditions when using polypropylene. The heating temperature is preferably between 170 and 300°C. A heating temperature of 170°C or higher ensures sufficient fluidity of the polypropylene resin, allowing the polypropylene composition to be sufficiently impregnated into the fiber mat, resulting in a suitable stampable sheet. On the other hand, a heating temperature of 300°C or lower prevents degradation of the polypropylene composition. Furthermore, the pressurized pressure is preferably 0.1 to 1 MPa. A pressurized pressure of 0.1 MPa or higher allows for sufficient impregnation of the polypropylene composition into the fiber mat, resulting in a suitable stampable sheet. On the other hand, a pressure of 1 MPa or lower prevents the polypropylene composition from flowing and the formation of burrs. Furthermore, while the cooling temperature is not particularly limited as long as it is below the freezing point of the thermoplastic resin in the polypropylene composition, a cooling temperature of 80°C or lower prevents deformation when removing the resulting stampable sheet. From these viewpoints, a cooling temperature of room temperature to 80°C is preferable.

[0037] Methods for obtaining a stampable sheet by heating, pressurizing, and cooling the above-mentioned laminate include press molding the laminate in a mold equipped with a heating device, and lamination, in which the laminate is heated and pressurized by passing it between two pairs of rollers equipped with heating devices. Lamination is particularly preferable because it allows for continuous production and thus has high productivity.

[0038] <Thickness of stampable sheet> The thickness of the stampable sheet of the present invention is typically 1 to 10 mm, preferably 2 to 5 mm. If the thickness of the stampable sheet is 1 mm or more, it is easy to manufacture. On the other hand, if the thickness of the stampable sheet is 10 mm or less, prolonged preheating is not required when processing the stampable sheet by stamping molding, and good moldability can be obtained.

[0039] <Thermosetting resin> The resin constituting the fiber-reinforced resin of the present invention is not particularly limited, but can be a thermosetting resin. Examples of thermosetting resins are not particularly limited and include vinyl urethane resin, unsaturated polyester resin, acrylic resin, epoxy resin, phenolic resin, melamine resin, furan resin, etc. These thermosetting resins can be used individually or in combination of two or more. Of these, vinyl urethane resin, epoxy resin, and phenolic resin are preferred in terms of resin properties, versatility, and cost.

[0040] In the present invention, the above-mentioned thermosetting resin and the fibers can be combined to form a fiber-reinforced composite material. As fiber-reinforced composite materials, prepregs in which a thermosetting resin composition is impregnated into a reinforcing fiber substrate containing continuous fibers, and sheet molding compounds (SMCs) in which a thermosetting resin composition is impregnated into a reinforcing fiber substrate containing short fibers can be used. A widely used method for manufacturing molded articles made from fiber-reinforced composite materials is compression molding of the fiber-reinforced composite material.

[0041] <<Content of thermosetting resin>> The thermosetting resin content in the battery housing of the present invention is preferably 20 to 80% by mass. When the thermosetting resin content is 20% by mass or more, the moldability is sufficient, and the molding of the battery housing becomes easy. On the other hand, when it is 80% by mass or less, the inorganic fiber content is sufficient, and sufficient flame resistance can be obtained. From the above viewpoint, the thermosetting resin content in the battery housing is preferably 35 to 70% by mass, and more preferably 40 to 60% by mass.

[0042] <Method for manufacturing a battery housing using thermosetting resin> Various methods can be used to manufacture the battery housing of the present invention using a thermosetting resin, but press molding is preferred from the viewpoint of productivity. For press molding, a prepreg in which a thermosetting resin composition is impregnated into a reinforcing fiber base material containing continuous fibers as described above, or a sheet molding compound (SMC) in which a thermosetting resin composition is impregnated into a reinforcing fiber base material containing short fibers can be used.

[0043] [Structure] The structure of the present invention comprises a battery housing and a battery cell. The battery housing of the present invention is as described in detail above. The structure in the present invention is preferably a battery, and is not particularly limited to any battery. Examples include secondary batteries such as lithium-ion batteries, nickel-metal hydride batteries, lithium-sulfur batteries, nickel-cadmium batteries, nickel-iron batteries, nickel-zinc batteries, sodium-sulfur batteries, lead-acid batteries, and air batteries. Among these, lithium-ion batteries are preferred, and in particular, the battery housing of the present invention is suitably used to suppress thermal runaway of lithium-ion batteries. That is, the battery housing of the present invention is preferably a battery housing for a lithium-ion battery. Furthermore, in the structure of the present invention, it is preferable that the mat layer of inorganic fiber B is arranged on the battery cell side in the battery housing. This configuration is advantageous because it allows for the gradual suppression of thermal runaway of the battery, specifically by suppressing the blast generated during thermal runaway with inorganic fiber B and suppressing high-temperature flames with high-heat-resistant fiber A.

[0044] [Electric Mobility] In this invention, electric mobility refers to transportation equipment such as vehicles, ships, and airplanes that operate using electricity as an energy source. Vehicles include not only electric vehicles (EVs) but also hybrid cars. The battery housing and battery cell structures of the present invention described above are highly safe and can extend the driving range, making them extremely useful for electric mobility applications using battery modules with high energy density. They are particularly useful for electric vehicles. [Examples]

[0045] The present invention will be described in detail below using examples, but the present invention is not limited to these examples. (Evaluation method) Evaluation of flame resistance For each example and comparative example, the stampable sheets prepared were fixed with a 150mm x 150mm area exposed so that the flame could be applied to the same spot. Using a φ1.2mm acetylene torch burner (Sakaguchi Seisakusho: WT-01), the oxygen pressure was adjusted to 0.15 MPa, the acetylene pressure to 0.001 MPa, and the distance between the sample and the burner to 145 mm so that the sample surface temperature reached 1200°C, and the flame was applied. After applying the flame for 5 minutes, the presence or absence of penetration was visually confirmed and the flame-blocking performance was evaluated. The evaluation criteria are as follows. ◎(Excellent): The flame does not penetrate, and the back surface temperature of the flame contact surface is less than 350℃. ○ (Good): The flame did not penetrate, but the back surface temperature of the flame contact surface was over 350°C. ×(Bad): The flames pierced through.

[0046] (Materials used) 1. Polypropylene resin (component A) "Novatec PP" (Melt Flow Rate: 60g / 10 mins), manufactured by Nippon Polypropylene Co., Ltd. 2. Flame retardant Phosphorus-based flame retardant composition (Manufactured by ADEKA Corporation, ADEKA Stab FP-2200, containing 50-60% by mass of piberazine pyrophosphate, 35-45% by mass of melamine pyrophosphate, and 3-6% by mass of zinc oxide, based on the total mass of the phosphorus-based flame retardant composition) 3. Dispersant α-olefin / maleic anhydride copolymer (manufactured by Mitsubishi Chemical Corporation, Diacarna 30M, weight-average molecular weight 7,800). 4. Fiberglass mat Swirl mat (basis weight 880g / m²) manufactured from continuous glass fibers (fiber diameter 23μm) of roving. 2 A fiberglass mat made by needle-punching ) was used. 5. Alumina fiber mat Mat manufactured from commercially available crystalline alumina fibers ("MAFTEC" (registered trademark) manufactured by Mitsubishi Chemical Corporation) (basis weight 900g / m²) 2 ) was used.

[0047] Preparation Example 1 (Preparation of Polypropylene Resin Composition) The above-mentioned polypropylene resin, flame retardant, and dispersant were melt-kneaded (230°C) in the proportions shown in Table 1 to prepare pellets of a polypropylene resin composition (hereinafter referred to as "PP composition 1").

[0048] Example 1 The following explanation will be given with reference to Figure 2. In Preparation Example 1, pellets of PP composition 1 were placed in an extruder, melted, and then extruded into a sheet. The extruded sheet-like PP (21, 21', and 21'' in Figure 2) was then laminated with glass fiber mat 23 and alumina fiber mat 22 in the mass ratios shown in Table 1 a and b, with PP as the outermost layer and glass fiber mat 23 and alumina fiber mat 22 in between. The laminated sheets were then heated and pressurized at 230°C for 4 minutes under a pressure of 0.3 MPa using a laminator, and then cooled and solidified to obtain a stampable sheet (thickness: 3.8 mm).

[0049] Molding of housing cover Using two of the stampable sheets a and one stampable sheet b obtained above, place b between two sheets a on either side and preheat in a far-infrared heating furnace (set temperature 270-300°C) for 4 minutes until the material temperature reaches 210°C. Next, the press machine with the mold installed was used to apply 150 kg / cm². 2 A box-shaped molded body (thickness: 3.0 mm) was obtained by applying pressure and holding for 30 seconds, then cooling and solidifying. The results of evaluation using the above method are shown in Table 2. Note that stampable sheets a to f, Examples 1 to 3, and Comparative Example 1 were all prepared by adding arbitrary additives in addition to the components shown in Tables 1 and 2, so that the total was 100% by mass.

[0050] Example 2 In the method for producing the stampable sheet of Example 1, the contents of polypropylene resin, flame retardant, and dispersant in the resin composition were changed as shown in c and d in Table 1, and d was overlapped with c on both sides, and the mass ratio was changed as shown in Table 2 to form a housing cover. Except for these changes, a molded body (thickness: 3.0 mm) was obtained in the same manner as in Example 1. The results of evaluation using the above method are shown in Table 2.

[0051] Example 3 In the method for producing the stampable sheet of Example 1, the resin composition was not made to contain a flame retardant or dispersant, the content of glass fibers and alumina fibers was changed as shown in c and e in Table 1, e was layered on both sides by c, the mass ratio was changed as shown in Table 2, and a housing cover was formed. Except for these changes, a molded body (thickness: 3.0 mm) was obtained in the same manner as in Example 1. The results of the evaluation using the above method are shown in Table 1.

[0052] Comparative Example 1 In Example 1, pellets and chopped carbon fibers were mixed in a kneader in the proportion of f shown in Table 1, and the resulting compound was formed into a sheet. A stampable sheet was obtained in the same manner as in Example 1, except that an alumina fiber mat was not used. Subsequently, three sheets of f were stacked, the mass ratio was changed as shown in Table 2, and a housing cover was formed. A molded body (thickness: 3.0 mm) was obtained in the same manner as in Example 1, except that a housing cover was formed. The results of the evaluation using the above method are shown in Table 2.

[0053] [Table 1]

[0054] [Table 2] *The dispersant ratio is the amount of dispersant (parts by mass) per 100 parts by mass of flame retardant.

[0055] Thus, it can be seen that the battery housing of the present invention, which contains highly heat-resistant fibers, has excellent flame-retardant properties. Furthermore, the battery housing of the present invention is lightweight because its main component is resin. [Industrial applicability]

[0056] The battery housing of the present invention has excellent flame resistance and, being primarily composed of resin, is highly processable. Furthermore, because it is lightweight, structures using the battery housing of the present invention are useful for electric mobility. [Explanation of symbols]

[0057] 10 Structures (Battery) 11 Battery Modules 12 Battery Packs 13 Battery Housing 20 Stampable Sheets 21 Polypropylene Sheets 21' Polypropylene Sheet 21'' Polypropylene Sheet 22 Fiberglass Mat 23 Alumina fiber mat

Claims

1. A battery housing made of fiber-reinforced resin, wherein the fibers include high heat-resistant fiber A, which has a melting or burning temperature in an atmospheric environment of 1000°C or more, and inorganic fiber B, which has a lower melting or burning temperature than the high heat-resistant fiber A, and the mass ratio of inorganic fiber B to high heat-resistant fiber A (B / A) is in the range of greater than 1 to 8.

2. The battery housing according to claim 1, wherein the mass ratio (B / A) of inorganic fiber B to high heat-resistant fiber A is in the range of 2 to 6.

3. The battery housing according to claim 1 or 2, wherein the average fiber diameter of the high heat-resistant fiber A is 3 to 25 μm and the average fiber length is 5 mm or more.

4. The battery housing according to any one of claims 1 to 3, wherein the average fiber length of the inorganic fiber B is longer than the average fiber length of the high heat-resistant fiber A.

5. The battery housing according to any one of claims 1 to 4, wherein the content of the high heat-resistant fiber A is 1 part by mass or more per 100 parts by mass of the fiber-reinforced resin.

6. The battery housing according to any one of claims 1 to 5, wherein the inorganic fiber B includes glass fiber.

7. The battery housing according to any one of claims 1 to 6, wherein the high heat-resistant fiber A is an alumina fiber.

8. A battery housing according to any one of claims 1 to 7, comprising a stampable sheet made of the aforementioned fiber-reinforced resin.

9. A structure having a battery housing and a battery cell according to any one of claims 1 to 8.

10. The structure according to claim 9, wherein the mat layer of inorganic fiber B in the battery housing is arranged on the battery cell side.

11. The structure according to claim 9 or 10, which is for use in an electric vehicle.

12. An electric mobility device comprising the structure described in any one of claims 9 to 11.

Images