Battery pack cover, battery pack unit and electric mobility

Abstract

To provide a battery pack cover (3) having excellent flame-resistant properties, a battery pack unit (1) using this battery pack cover, and electric mobility using this battery pack unit.SOLUTION: A battery pack cover for use in a battery pack includes a cover base material (5) and an inorganic fiber molded body (4) having tensile strength of 20 N or more. There are also provided a battery pack unit using this battery pack cover, and electric mobility using this battery pack unit.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This disclosure relates to a battery pack cover, a battery pack unit, and electric mobility. [Background technology]

[0002] A battery pack unit used in electric mobility devices such as electric vehicles has a housing with a portion open, a battery pack placed inside the housing, and a battery pack cover that closes the open portion (Patent Document 1: WO2012 / 167921). Paragraph 0081 of Patent Document 1 exemplifies aluminum, aluminum alloy, magnesium, magnesium alloy, AlSiC, titanium, titanium alloy, steel, stainless steel, and special steel as constituent materials for the battery pack cover.

[0003] In battery modules used in mobility devices such as electric vehicles, insulating or heat-absorbing materials are sometimes placed between battery cells to prevent thermal runaway of the battery.

[0004] Patent Document 2 (EP2506336A1) discloses a battery pack thermal management system for minimizing the effects of thermal runaway, comprising multiple batteries and an airtight battery pack packaging, wherein the battery pack packaging has a cavity and is equipped with a gas exhaust port on its outer wall, and is configured such that when at least one battery experiences thermal runaway, the gas exhaust port allows gas to pass to the outside of the battery pack packaging.

[0005] Furthermore, battery units are known in which mica sheets or similar materials are attached to the sides of the battery pack cover that encloses the battery module in order to improve fire resistance. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] International Publication No. 2012 / 167921 [Patent Document 2] European Patent Application Publication No. 2506336 [Overview of the project] [Problems that the invention aims to solve]

[0007] To extend driving range, the energy density of battery modules installed in electric vehicles tends to increase, and the demands on battery heat generation and the risk of thermal runaway are growing. In the event of ignition that cannot be contained by the insulating materials placed between battery cells, the objective of this invention is to provide a battery pack cover with excellent flame-retardant properties in order to delay the spread of fire to interior materials. Furthermore, the objective is to provide a battery pack unit using this battery pack cover and an electric mobility device using this battery pack unit. [Means for solving the problem]

[0008] Mica sheets are made of a hard, brittle mineral and are therefore easily damaged by vibrations during driving. Furthermore, meeting the requirements for flame resistance and other functionalities increases the vehicle's weight. On the other hand, lightweight flame-resistant structures are easily blown away by blasts and lack sufficient flame resistance to contain flames erupting from the battery pack. Therefore, the inventors focused on the fact that an inorganic fiber molded body with a specific range of tensile strength can withstand the blast erupting during battery thermal runaway and prevent flame penetration, thus improving the flame resistance of the battery pack cover without compromising load capacity. The gist of this invention is as follows.

[0009] [1] A battery pack cover used in a battery pack, A battery pack cover characterized by comprising a cover base material and an inorganic fiber molded body with a tensile strength of 20 N or more in the tensile test described below.

[0010] <Tensile Test> A test piece with a width of 25 mm and a length of 160 mm is punched out from an inorganic fiber molded body, the test piece is pulled in the longitudinal direction at a speed of 25 mm / min using a tensile testing machine, and the maximum measured load is defined as the tensile strength.

[0011] [2] The battery pack cover according to [1], wherein the cover base material is a metal base material.

[0012] [3] The battery pack cover according to [1] or [2], which is a laminate formed by stacking the cover base material and the inorganic fiber molded body.

[0013] [4] The battery pack cover according to any one of [1] to [3], which does not penetrate in a flame test at a flame temperature of 1000°C for 5 minutes.

[0014] [5] The battery pack cover according to any one of [1] to [4], wherein the inorganic fiber molded body is composed of inorganic fibers having an average fiber length of 3 mm or more.

[0015] [6] The battery pack cover according to any one of [1] to [5], wherein the inorganic fiber molded body is a woven fabric or a non-woven fabric.

[0016] [7] The battery pack cover according to any one of [1] to [6], wherein the inorganic fiber molded body is a needle blanket.

[0017] [8] A battery pack unit comprising the battery pack cover according to any one of [1] to [7] and a battery pack.

[0018] [9] The battery pack unit according to [8], wherein the inorganic fiber molded body of the battery pack cover is disposed on the battery pack side.

[0019]

[10] An electric mobility comprising the battery pack unit according to [8] or [9]. [Advantageous Effects of Invention]

[0020] The inorganic fiber molded body used in this invention has a tensile strength of 20N or more and is excellent in preventing flames from penetrating the battery during thermal runaway. Therefore, a battery cover equipped with this inorganic fiber molded body has excellent flame resistance. [Brief explanation of the drawing]

[0021] [Figure 1] A schematic cross-sectional view showing an example of a battery pack unit. [Modes for carrying out the invention]

[0022] The battery pack cover of the present invention is used in a battery pack unit. The battery pack unit comprises a battery pack and a battery cover.

[0023] Figure 1 is a schematic cross-sectional view showing an example of a battery pack unit. This battery pack unit 1 further includes a housing 2 which has an open portion 2a, a battery pack cover 3 which closes the open portion 2a, and a battery pack 10 etc. which are placed inside the housing 2. However, the housing is not necessarily required.

[0024] The battery pack cover 3 comprises an inorganic fiber molded body 4 and a cover base material 5. Both the inorganic fiber molded body 4 and the cover base material 5 are plate-shaped and are superimposed on each other. However, they may be bonded together with an adhesive. The inorganic fiber molded body 4 is positioned inside the battery pack unit 1 relative to the cover base material 5.

[0025] The battery pack 10, located inside the housing 2, comprises multiple battery modules 11.

[0026] This battery pack unit 1 can improve the flame resistance of the battery pack cover without compromising loadability, and is therefore suitable for use in batteries for electric mobility devices such as electric vehicles, electric motorcycles, and ships. The battery is not particularly limited and 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 are particularly suitable for use in suppressing thermal runaway of lithium-ion batteries.

[0027] [Cover material] The cover base material 5 of the battery pack cover 3 is not particularly limited, and housing materials such as metal base materials and reinforced resin base materials can be used. From the viewpoint of flame resistance, metal base materials are preferred, and aluminum, aluminum alloys, magnesium, magnesium alloys, titanium, titanium alloys, iron, stainless steel, etc. are suitable. The thickness of the metal base material 5 is preferably 0.1 to 10 mm, particularly 0.3 to 7 mm, but is not limited to this.

[0028] [Inorganic fiber molded material] The inorganic fiber molded article used in the present invention has a tensile strength of 20 N or more, preferably 25 N or more, and particularly preferably 30 N or more. The tensile strength of the inorganic fiber molded article is preferably as high as possible, and there is no upper limit, but it is preferably 100 kN or less, and particularly preferably 50 kN or less. The tensile strength is the value measured by the method described in the examples below.

[0029] The inorganic fibers constituting this inorganic fiber molded body are not particularly limited and include silica, alumina / silica, zirconia containing these, spinel, titania, and other single or composite fibers. The inorganic fibers are preferably alumina / silica-based fibers, and particularly preferably crystalline alumina / silica-based fibers. The composition ratio (weight ratio) of alumina / silica in the alumina / silica-based fibers is preferably in the range of 60-95 / 40-5, more preferably in the range of 70-84 / 30-16, and particularly preferably in the range of 70-76 / 30-24.

[0030] Furthermore, the inorganic fibers have an average fiber length of preferably 1 mm or more, more preferably 2 mm or more, and even more preferably 3 mm or more. The average fiber length is preferably 3.0 × 10⁻⁶. 3 mm or less, more preferably 1.0 × 10 3 The fibers are mm in length. The average fiber diameter of the inorganic fibers is preferably 3 to 10 μm, and particularly preferably 5 to 8 μm. It is preferable that the inorganic fiber molded article has high tensile strength when the average fiber length and average fiber diameter of the inorganic fibers are within this range. It is also preferable that the amount of dust generated that floats in the air is suppressed when the average fiber length and average fiber diameter of the inorganic fibers are within this range. The average fiber length of the inorganic fibers is the average value of 300 fibers measured by microscopic observation. The average fiber diameter is the average value of 100 fibers measured by microscopic observation.

[0031] The inorganic fiber molded body used in this invention is not limited in terms of manufacturing method or shape, as long as it has the desired tensile strength. However, it is preferable that it is composed of inorganic fibers and is a woven or nonwoven fabric. If the inorganic fiber molded body is a woven fabric composed of inorganic fibers, the manufacturing method is not limited, and known methods for weaving fabrics can be applied. Even if the inorganic fiber molded body is a nonwoven fabric composed of inorganic fibers, the manufacturing method is not limited, but it is preferably a needle blanket that has been subjected to a needling treatment. Needling treatment creates needle marks on the inorganic fiber molded body. The inorganic fiber molded body is in the form of a mat with a predetermined thickness. The surface perpendicular to the thickness direction of the inorganic fiber molded body may be referred to as the mat surface below. Also, the side surface (surface in the thickness direction) perpendicular to the mat surface of the inorganic fiber molded body may be referred to as the end surface.

[0032] In one embodiment of the present invention, the inorganic fiber molded body has needle marks. The needle mark density is the area per unit area (1 cm²) of the mat surface of the inorganic fiber molded body after firing. 2 This refers to the number of needle marks per )

[0033] When visible light is applied to the mat surface of the inorganic fiber molded body, the amount of transmitted light at the needle marks is greater than the amount of transmitted light in regions other than the needle marks, so the transmitted light is observed as light spots on the peeled surface. The number of needle marks is obtained by counting the number of light spots due to transmission through this peeled surface.

[0034] In the present invention, the unit area of the mat surface of the inorganic fiber molded body (1 cm 2 ), the number of needle marks per unit area (needle mark density), as an average value over the entire mat surface, is preferably 1 piece / cm 2 or more, more preferably 3 pieces / cm 2 or more, and is preferably 100 pieces / cm 2 or less, more preferably 50 pieces / cm 2 or less.

[0035] The basis weight (mass per unit area) of the inorganic fiber molded body is 50 g / m 2 or more, preferably 80 g / m 2 or more, more preferably 100 g / m 2 or more, still more preferably 200 g / m 2 or more, particularly preferably 400 g / m 2 or more. Also, the basis weight of the inorganic fiber molded body is preferably 3000 g / m 2 or less, more preferably 2500 g / m 2 or less, particularly preferably 2000 g / m 2 or less.

[0036] The thickness of the inorganic fiber molded body is preferably 0.1 mm or more, more preferably 0.3 mm or more, particularly 0.5 mm or more. Also, the thickness of the inorganic fiber molded body is preferably 25 mm or less, more preferably 20 mm or less, particularly preferably 15 mm or less. When the basis weight and thickness of the inorganic fiber molded body fall within this range, the tensile strength of the inorganic fiber molded body falls within an appropriate range, which is preferable. It is also preferable from the viewpoints of loadability and space efficiency in mobility.

[0037] The basis weight and thickness of the inorganic fiber molded body can be set to the above range by adjusting the amount of fiber per unit area when stacking the inorganic fiber aggregates constituting the inorganic fiber molded body using a folding device.

[0038] [Method for manufacturing inorganic fiber molded articles] Inorganic fiber molded articles can be manufactured by a method comprising the steps of obtaining a mat-like aggregate of inorganic fiber precursors by a sol-gel method, applying a needling treatment to the obtained mat-like aggregate of inorganic fiber precursors, and firing the needled mat-like aggregate of inorganic fiber precursors to form an inorganic fiber molded article. However, inorganic fiber molded articles may be manufactured by other methods.

[0039] The following describes an example of a method for manufacturing this inorganic fiber molded article, using the method for manufacturing an alumina / silica-based fiber molded article as an example. However, the inorganic fiber molded article of the present invention is not limited in any way to an alumina / silica-based fiber molded article, and as mentioned above, it may be a molded article made of silica, zirconia, spinel, titania, or composite fibers thereof.

[0040] <Spinning Process> To produce a mat-like aggregate of alumina / silica fibers by the sol-gel method, first, a spinning solution containing basic aluminum chloride, a silicon compound, an organic polymer as a thickener, and water is spun by the blowing method to obtain an aggregate of alumina / silica fiber precursors.

[0041] <<Preparation of spinning solution>> Basic aluminum chloride; Al(OH) 3-x Cl xThis can be prepared, for example, by dissolving metallic aluminum in hydrochloric acid or an aqueous solution of aluminum chloride. The value of x in the above chemical formula is usually 0.45 to 0.54, preferably 0.5 to 0.53. Silica sol is preferably used as the silicon compound, but other water-soluble silicon compounds such as tetraethyl silicate and water-soluble siloxane derivatives can also be used. Water-soluble polymer compounds such as polyvinyl alcohol, polyethylene glycol, and polyacrylamide are preferably used as organic polymers. The degree of polymerization of these is usually 1000 to 3000.

[0042] The spinning solution preferably has a ratio of aluminum derived from basic aluminum chloride to silicon derived from silicon compounds, which is typically 99:1 to 65:35, preferably 99:1 to 70:30, when converted to a weight ratio of Al2O3 to SiO2, with an aluminum concentration of 170 to 210 g / L and an organic polymer concentration of 20 to 50 g / L.

[0043] If the amount of silicon compounds in the spinning solution is less than the above range, the alumina constituting the short fibers is more likely to become α-alumina, and the short fibers are more likely to become brittle due to the coarsening of the alumina particles. On the other hand, if the amount of silicon compounds in the spinning solution is more than the above range, the amount of silica (SiO2) produced together with mullite (3Al2O3·2SiO2) increases, and the heat resistance tends to decrease.

[0044] If the aluminum concentration in the spinning solution is less than 170 g / L or the organic polymer concentration is less than 20 g / L, in either case, an appropriate viscosity of the spinning solution cannot be obtained, and the fiber diameter of the resulting alumina / silica-based fibers will be small. In other words, as a result of too much free water in the spinning solution, the drying rate during spinning by the blowing method is slow, the stretching proceeds excessively, the fiber diameter of the spun precursor fibers changes, and short fibers with a predetermined average fiber diameter and a sharp fiber diameter distribution cannot be obtained. Moreover, if the aluminum concentration is less than 170 g / L, productivity decreases. On the other hand, if the aluminum concentration exceeds 210 g / L or the organic polymer concentration exceeds 50 g / L, in either case, the viscosity is too high to become a spinning solution. The preferred concentration of aluminum in the spinning solution is 180-200 g / L, and the preferred concentration of organic polymer is 30-40 g / L.

[0045] The above spinning solution is prepared by adding an amount of silicon compound and an organic polymer in the above Al2O3:SiO2 ratio to an aqueous solution of basic aluminum chloride, and concentrating it so that the concentrations of aluminum and organic polymer fall within the above range.

[0046] ≪Blowing≫ Spinning (fibrillation of the spinning solution) is usually carried out by a blowing method, in which the spinning solution is supplied into a high-speed spinning airflow, thereby obtaining an alumina short fiber precursor. There are no particular restrictions on the structure of the spinning nozzle used in the above spinning process, but a structure in which the airflow blown out from the air nozzle and the spinning solution flow pushed out from the spinning solution supply nozzle are parallel flows, and moreover, the parallel flow of air is sufficiently rectified to come into contact with the spinning solution, is preferred, for example, as described in Japanese Patent Publication No. 2602460.

[0047] Furthermore, during spinning, it is preferable that, first, sufficiently stretched fibers are formed from the spinning solution under conditions where the evaporation of moisture and the decomposition of the spinning solution are suppressed, and then these fibers are dried quickly. To achieve this, it is preferable to change the atmosphere from a state that suppresses the evaporation of moisture to a state that promotes the evaporation of moisture during the process from when the fibers are formed from the spinning solution until they reach the fiber collector.

[0048] Alumina / silica fiber precursors can be collected and accumulated using an accumulation device that has a structure in which an endless wire mesh belt is set up approximately perpendicular to the spinning airflow, and the spinning airflow containing the alumina / silica fiber precursors is made to collide with the endless belt while it is rotating, thereby recovering them as a continuous sheet-like accumulation (thin layer sheet) of alumina / silica fiber precursors.

[0049] The basis weight of this thin sheet is preferably 10 to 200 g / m². 2 Particularly preferred is 30-100 g / m². 2 This is the extent of it, but it is not limited to this.

[0050] The thin sheets recovered from the above-mentioned accumulation device can be further laminated. Specifically, for example, an aggregate of inorganic fiber precursors (thin sheets) can be continuously drawn out and sent to a folding device, where they can be folded to a predetermined width and stacked while being continuously moved in a direction perpendicular to the folding direction to form a laminated aggregate of inorganic fiber precursors (laminated sheet). By laminating the thin sheets in this way, the basis weight (weight) of the laminated sheet becomes uniform throughout the entire sheet. As the above-mentioned folding device, the one described in Japanese Patent Application Publication No. 2000-80547 can be used.

[0051] <Needling aid or friction reducer application process> Needling aids or anti-friction agents are applied to the sheet surface of a thin sheet or laminated sheet of alumina / silica-based inorganic fiber precursor obtained by spinning, as needed. It is preferable to apply the needling aid or anti-friction agent to both sheet surfaces.

[0052] As a needling aid, any agent that has the effect of strengthening the filaments near the mat surface of the inorganic fiber precursor aggregate can be used, and various coating agents, such as acrylic polymer coating agents, can be used.

[0053] As a friction reducer, surfactants or emulsions that reduce friction between the needle and the fiber can be used. Needling aids and friction reducers are applied by coating (wet coating) the solution or dispersion.

[0054] <Needling process> A laminated sheet of alumina / silica-based inorganic fiber precursors obtained by spinning is, if necessary, impregnated with a needling aid and / or an anti-friction agent, and then subjected to a needling process in which a barbed needle is inserted and removed from the laminated sheet. The needling process may be performed from only one side of the laminated sheet or from both sides. Preferably, it is performed from both sides.

[0055] The needle is preferably inserted and withdrawn perpendicular to the sheet surface of the laminated sheet. The needle is inserted deeper than the center in the thickness direction of the laminated sheet. The needle may also be inserted so as to penetrate the laminated sheet in the thickness direction.

[0056] In this way, needle marks are formed on the inorganic fiber molded body by the needling process. That is, when a needling process is performed in which a barbed needle is inserted into and removed from a laminated sheet, at least some of the fibers are extended in the approximate thickness direction by the needle at the locations where the needle was inserted and removed. As a result, needle marks are formed on the surface of the inorganic fiber molded body. Within the inorganic fiber molded body that has undergone the needling process, the strands of inorganic fibers that extend in the approximate thickness direction are called warp strands.

[0057] Needling is performed to adjust the bulk density and peel strength of an inorganic fiber molded body by forming warp threads.

[0058] The needle marks may penetrate the inorganic fiber molded body, or they may penetrate from one mat surface and extend without reaching the other mat surface.

[0059] <Firing Process> The inorganic fiber molded body is preferably a sintered body obtained by sintering a needling-treated inorganic fiber precursor. Sintering is usually carried out at a temperature of 900°C or higher, preferably 1000 to 1300°C. A sintering temperature of 900°C or higher is preferable because it allows for sufficient crystallization, resulting in alumina / silica-based fibers with excellent strength. A sintering temperature of 1300°C or lower is also preferable because it prevents excessive grain growth of the fiber crystals, resulting in alumina / silica-based fibers with moderate strength.

[0060] [Example 1] <Manufacturing of inorganic fiber molded products> To an aqueous solution of basic aluminum chloride (aluminum content 165 g / L, Al / Cl = 1.8 (atomic ratio)), silica sol was added so that the final alumina fiber composition would be Al2O3:SiO2 = 72:28 (weight ratio). After adding polyvinyl alcohol, the solution was concentrated to prepare a spinning solution with a viscosity of 70 poise (25°C) and an alumina-silica content of approximately 35% by weight.

[0061] The above spinning solution was spun using the blowing method. As the spinning nozzle, a spinning nozzle with the same structure as that described in Figure 6 of Japanese Patent Publication No. 2602460 was used. Furthermore, for cotton collection, an endless belt made of wire mesh was set approximately perpendicular to the spinning airflow, and the cotton was collected as a continuous sheet (thin sheet) using a collection device with a structure that caused the spinning airflow containing alumina / silica-based fiber precursors to collide with the endless belt while it was rotating.

[0062] The thin sheets recovered from the accumulation device were coated with an anti-friction agent by spray, then continuously drawn out and sent to a folding device. There, they were folded to a predetermined width and stacked, while being continuously moved in a direction perpendicular to the folding direction to form laminated sheets. The folding device used was one with the same structure as that described in Japanese Patent Publication No. 2000-80547. Needling was performed by punching using a needle punching machine.

[0063] Afterward, it is fired at 1200°C, resulting in a basis weight of 900g / m². 2(Thickness 5.6mm, bulk density 0.16g / cm³) 3 An inorganic fiber molded body 1 consisting of crystalline alumina / silica fibers was obtained. Sintering was performed in an electric furnace at a heating rate of 5°C / min to 1200°C, held at 1200°C for 30 minutes, and then allowed to cool naturally.

[0064] The composition ratio of this crystalline alumina / silica fiber was alumina / silica = 72 / 28 (by weight), and the average fiber diameter (average of 100 fibers) of the crystalline alumina / silica fiber, measured by microscopic observation of the inorganic fiber molded body, was 5.5 μm.

[0065] <Manufacturing of battery pack covers> The obtained inorganic fiber molded body was layered with an aluminum alloy plate (Al alloy plate A5052, 0.8 mm thick) as a cover base material to form a laminate, and the battery pack cover 1 of Example 1 was manufactured.

[0066] [Example 2] In Example 1, the inorganic fiber molded article with reduced fiber content per unit area had a basis weight of 600 g / m². 2 (Thickness 4.8mm, bulk density 0.12g / cm³) 3 Except for the difference mentioned above, an inorganic fiber molded body 2 was manufactured in the same manner as in Example 1, and a laminate was formed by stacking it with an aluminum alloy plate (Al alloy plate A5052, thickness 0.8 mm) to produce the battery pack cover 2 of Example 2. The composition ratio of this crystalline alumina / silica fiber was alumina / silica = 72 / 28 (by weight), and the average fiber diameter (average value of 100 fibers) of the crystalline alumina / silica fiber measured by microscopic observation of the inorganic fiber molded body was 5.5 μm.

[0067] [Example 3] In Example 1, the bulk density was reduced by reducing the needle mark density, resulting in a basis weight of 900 g / m². 2 (Thickness 6.3mm, bulk density 0.14g / cm³) 3Except for the difference mentioned above, an inorganic fiber molded body 3 was manufactured in the same manner as in Example 1, and a laminate was formed by stacking it with an aluminum alloy plate (Al alloy plate A5052, thickness 0.8 mm) to produce the battery pack cover 3 of Example 3. The composition ratio of this crystalline alumina / silica fiber was alumina / silica = 72 / 28 (by weight), and the average fiber diameter (average value of 100 fibers) of the crystalline alumina / silica fiber measured by microscopic observation of the inorganic fiber molded body was 5.5 μm.

[0068] [Example 4] As the inorganic fiber molded body 4, Denka's Arsen NBK80-10 was used.

[0069] The composition ratio of this crystalline alumina / silica fiber was alumina / silica = 80 / 20 (by weight), and the average fiber diameter (average value of 100 fibers) of the crystalline alumina / silica fiber, measured by microscopic observation of the inorganic fiber molded body, was 4.4 μm. The inorganic fiber molded body 4 and an aluminum alloy plate (Al alloy plate A5052, thickness 0.8 mm) were layered to form a laminate, and the battery pack cover 4 of Example 4 was manufactured.

[0070] [Example 5] As the inorganic fiber molded body 5, ITM Corporation (now Isolite Industries Co., Ltd.), FMX16 blanket LXS150 was used. The composition ratio of this crystalline alumina / silica fiber was alumina / silica = 72 / 28 (by weight), and the average fiber diameter (average value of 100 fibers) of the crystalline alumina / silica fiber, measured by microscopic observation of the inorganic fiber molded body, was 4.1 μm. The inorganic fiber molded body 5 and an aluminum alloy plate (Al alloy plate A5052, thickness 0.8 mm) were layered to form a laminate, and the battery pack cover 5 of Example 5 was manufactured.

[0071] [Example 6] In Example 1, the inorganic fiber molded article with reduced fiber content per unit area had a basis weight of 432 g / m². 2 (Thickness 3.5mm, bulk density 0.12g / cm³) 3Except for the difference mentioned above, an inorganic fiber molded body 6 was manufactured in the same manner as in Example 1, and a laminate was formed by stacking it with an aluminum alloy plate (Al alloy plate A5052, thickness 0.8 mm) to produce the battery pack cover 6 of Example 6. The composition ratio of this crystalline alumina / silica fiber was alumina / silica = 72 / 28 (by weight), and the average fiber diameter (average value of 100 fibers) of the crystalline alumina / silica fiber measured by microscopic observation of the inorganic fiber molded body was 5.6 μm.

[0072] [Comparative Example 1] The inorganic fiber molded body 1 obtained in Example 1 was crushed using a dry defibration device, and water was added to 92.4% by weight of the short-fiberized inorganic fibers to form a dispersion. 6.0% by weight of modified acrylic ester copolymer (latex), 0.5% by weight of anionic acrylic resin (paper strength enhancer), 1.0% by weight of aluminum sulfate, and 0.1% by weight of polymer flocculant were added to this dispersion, and the mixture was stirred to prepare a slurry. The slurry was then processed using a papermaking machine to produce a paper with a dry basis weight of 700 g / m². 2 (Thickness 5.3mm, bulk density 0.13g / cm³) 3 An inorganic fiber molded body was obtained by adjusting the suction speed and slurry supply speed to achieve the following result. Subsequently, the inorganic fiber molded body and an aluminum alloy plate (Al alloy plate A5052, thickness 0.8 mm) were stacked to form a laminate, and the battery pack cover of Comparative Example 1 was manufactured.

[0073] <<Measurement of physical properties of inorganic fiber molded materials>> The tensile strength, fiber length, thickness, and needle mark density of the inorganic fiber molded articles obtained in each of the above examples and comparative examples were measured as follows. The results are shown in Table 1.

[0074] • Tensile strength measurement test method The tensile strength was measured using a tensile testing machine. The size of the parallel section (effective section) of the test specimen was 25 mm x 100 mm, and the overall size was 25 mm x 160 mm. The inorganic fiber molded product was cut to the above size using a die, mounted on a tensile testing machine, and pulled at a speed of 25 mm / min. The maximum value of the load was defined as the tensile strength.

[0075] • Method for measuring average fiber length Measurements were taken using an optical microscope. A 2g sample was taken from the inorganic fiber molded body using tweezers and placed in a 1000ml beaker with 800ml of water. Ultrasonic dispersion was performed using a Tokyo Rikakikai apparatus (model: USC-200Z38S-23). ​​Then, 20-25ml of the dispersed solution was added to a 200ml beaker containing 150ml of water to prepare the sample solution. The sample solution was vigorously stirred with a stirrer, 1-2ml was taken and dropped onto a glass slide, a coverslip was placed on top, and the sample was observed under an optical microscope. The length of the fibers displayed on the microscope monitor was read in 1mm increments. 300 samples were collected, and the length of each fiber was calculated using the following conversion formula.

[0076] Conversion formula: Fiber length (μm) = Measured value (mm) ÷ Magnification × 1000 • Method for measuring thickness The measurement was performed using a digital dial gauge. The measured load was 4.9 kPa (50 g / cm²). 2 The minimum measurement scale is 0.01 mm. A test piece cut out using the method described later in the flame test method was randomly measured at 5 points using the measuring jig, and the average of the 5 points was used as the representative measurement value.

[0077] • Method for measuring needle mark density The number of needle marks per unit area was calculated as the average of the number of needle marks on one peeled surface and the number of needle marks on the other peeled surface, obtained by peeling off a section of the inorganic fiber molded material from the center of its thickness per unit area. Note that areas with warp threads were counted as needle marks.

[0078] In practice, when visible light is shone on one side of an inorganic fiber molded body, transmitted light is observed on the delamination surface. By counting the number of light spots and warp threads transmitted to this delamination surface, the total number of needle marks per unit area can be counted.

[0079] The needle mark density for Example 1 and Example 2 was measured using the method described above, and the result was 27.3 marks / cm² for both. 2 , 19,3 pieces / cm 2 That's what happened.

[0080] ≪Flame Testing Method≫ The inorganic fiber molded articles 1-8 of Examples 1-7 and Comparative Example 1 were punched out using a die at 3600 mm. 2 It was cut to the following size. The cut inorganic fiber molded body was cut from each aluminum alloy plate (3600mm 2 A test specimen was prepared by stacking two pieces (with a thickness of 0.8 mm) and then conducting the following flame test.

[0081] The test specimen was clamped and fixed in a stainless steel jig, and positioned 70 mm away from the tip of the torch burner. The test specimen was positioned so that the inorganic fiber molded body side faced the burner, and the mat surface of the inorganic fiber molded body was approximately perpendicular to the burner axis.

[0082] This torch burner (Sakaguchi Seisakusho: WT-01, nozzle diameter 1.2 mm) was supplied with a flame and air for 5 minutes at O2 0.5 MPa, C2H 20.02 MPa, and an air pressure of 0.2 MPa from an air nozzle (discharge port diameter 3.0 mm, positioned 100 mm away from the test piece, with the mat surface of the inorganic fiber molded material approximately perpendicular to the air nozzle axis direction), and a flame at a temperature of 1000°C was sprayed towards the test piece.

[0083] Five minutes after the flame was directed at the inorganic fiber molded specimen, the specimen was removed, and it was visually inspected to see if the inorganic fiber molded specimen had been penetrated by the flame. The results are shown in Table 1.

[0084] [Table 1]

[0085] <Consideration> As shown in Table 1, the battery pack cover of the present invention has excellent flame resistance, as flames do not penetrate the inorganic fiber molded body.

[0086] Although the present invention has been described in detail using specific embodiments, it will be apparent to those skilled in the art that various modifications are possible without departing from the intent and scope of the invention.

[0087] This application is based on Japanese Patent Application No. 2020-206897, filed on 14 December 2020, which is incorporated herein by reference in its entirety. [Explanation of Symbols]

[0088] 1 Battery Pack Unit 2 Housing 3. Battery pack cover 4. Inorganic fiber molded body 5 Cover base material 10 Battery Packs 11 Battery Modules

Claims

1. A battery pack cover used for a battery pack, Cover base material and The inorganic fiber molded article has a tensile strength of 20 N or more in the tensile test described below, The cover substrate and the inorganic fiber molded body are directly superimposed or bonded together with an adhesive. The inorganic fiber molded body is a needle blanket, A battery pack cover characterized by not having an additional layer on the side opposite to the cover substrate in an inorganic fiber molded body. <Tensile Test> A test specimen measuring 25 mm in width and 160 mm in length is cut out from an inorganic fiber molded body. The test specimen is pulled in the longitudinal direction at a speed of 25 mm / min using a tensile test, and the maximum value of the measured load is defined as the tensile strength.

2. A battery pack cover used for a battery pack, Cover base material and The inorganic fiber molded article has a tensile strength of 20 N or more in the tensile test described below, The cover substrate and the inorganic fiber molded body are directly superimposed or bonded together with an adhesive. The inorganic fiber molded body is a needle blanket, The battery pack cover is characterized in that the inorganic fiber molded body is composed of inorganic fibers with an average fiber length of 3 mm or more and 7.9 mm or less. <Tensile Test> A test specimen measuring 25 mm in width and 160 mm in length is cut out from an inorganic fiber molded body. The test specimen is pulled in the longitudinal direction at a speed of 25 mm / min using a tensile test, and the maximum value of the measured load is defined as the tensile strength.

3. The battery pack cover according to claim 1 or 2, wherein the cover substrate is a metal substrate or a reinforced resin substrate.

4. A battery pack cover according to any one of claims 1 to 3, which does not penetrate a flame test at a flame temperature of 1000°C for 5 minutes.

5. The battery pack cover according to any one of claims 1, 3, or 4, wherein the inorganic fiber molded body is composed of inorganic fibers with an average fiber length of 3 mm or more.

6. The battery pack cover according to any one of claims 1 to 5, wherein the inorganic fiber molded body is a woven fabric or a nonwoven fabric.

7. A battery pack unit having a battery pack cover and a battery pack according to any one of claims 1 to 6.

8. A battery pack unit according to claim 7, A battery pack unit in which the inorganic fiber molded body of the battery pack cover is positioned on the battery pack side.

9. An electric mobility device comprising the battery pack unit according to claim 7 or 8.

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