Thermal insulation material and thermal insulation material production method

Abstract

A heat insulation material 3 is used in a battery pack including a battery group in which unit cells and heat insulation materials are alternately laminated, and comprises: a radiation shielding member 31 that is sheet-like and suppresses radiation; a plate-like member 32 that is arranged on at least one side of two main surfaces of the radiation shielding member 31 and has heat insulation properties; and a cushion member 34 that is disposed on the same side and / or the opposite side of the one side of the two main surfaces of the radiation shielding member 31 and absorbs expansion when the unit cells expand. As a result, it is possible to provide a heat insulating material 3 and a heat insulating material manufacturing method with which it is possible to suppress heating of an adjacent unit cell when the unit cell abnormally generates heat, as compared to a case in which the configuration of the present invention is not provided.

Description

Heat insulating material and method for manufacturing the same

[0001] The present invention relates to a thermal insulating material and a method for manufacturing the thermal insulating material. In particular, the present invention relates to a thermal insulating material used in a battery pack including a group of batteries in which unit cells and thermal insulating materials are alternately stacked, and a method for manufacturing the thermal insulating material.

[0002] Conventionally, assembled batteries including a group of batteries in which unit cells and insulating materials are alternately stacked have been known. The insulating materials prevent heat transfer to adjacent unit cells when a unit cell generates abnormal heat due to factors such as a short circuit or overcharging. This prevents heat transfer to adjacent unit cells, preventing or delaying the spread of fire even if a unit cell generates abnormal heat and, for example, catches fire.

[0003] Patent Document 1 discloses a partition member that separates cells constituting a battery pack or separates cells from components other than the cells. This partition member includes an inner container capable of holding a liquid and an outer container having an internal space that accommodates the liquid and the inner container in a sealed state, and the inner container is sealed under a pressure of 0.05 kgf / cm. ２ Water absorption rate 1 indicates the water absorption rate when compressed for 1 minute under a pressure of 5 kgf / cm ２ The ratio of [water absorption rate 2] / [water absorption rate 1] to water absorption rate 2, which indicates the water absorption rate when compressed at 100°C for 1 minute, is 0.4 or more.

[0004] International Publication No. 2019 / 107561

[0005] However, conventional heat insulating materials have insufficient heat insulating function and are unable to sufficiently prevent adjacent cells from overheating when a cell abnormally heats up. An object of the present invention is to provide a heat insulating material and a method for manufacturing a heat insulating material that can suppress overheating of adjacent cells when a cell abnormally heats up, compared to a case not equipped with the configuration of the present invention.

[0006] In order to solve the above problems, the present invention provides an insulating material for use in a battery pack including a group of batteries in which single cells and insulating materials are alternately stacked, the insulating material comprising: a sheet-shaped radiation-blocking member that suppresses radiation; a plate-shaped member that is arranged on at least one side of the two main surfaces of the radiation-blocking member and has insulating properties; and a cushioning member that is arranged on the same side and / or the opposite side of the one side of the two main surfaces of the radiation-blocking member and absorbs the expansion of the single cells when they expand.

[0007] The present invention also provides a method for manufacturing an insulating material used in a battery pack including a group of batteries in which batteries and insulating materials are stacked alternately, the method comprising the steps of: bonding together a sheet-like radiation-blocking member that suppresses radiation and a plate-like member that has insulating properties and is arranged on at least one side of two main surfaces of the radiation-blocking member; and bonding a cushioning member that absorbs the expansion of the single cells to the same side and / or the opposite side of the one side of the two main surfaces of the radiation-blocking member.

[0008] The object of the present invention is to provide a heat insulating material and a method for manufacturing the heat insulating material that can suppress heating of adjacent unit cells when a unit cell generates abnormal heat, compared to a case where the configuration of the present invention is not provided.

[0009] 1A to 1D are diagrams illustrating a battery group included in a battery pack. (a) to (d) are diagrams illustrating a first example of the configuration of the insulating material according to the present embodiment. (a) to (d) are diagrams illustrating a second example of the configuration of the insulating material according to the present embodiment. (a) to (d) are diagrams illustrating a third example of the configuration of the insulating material according to the present embodiment. (a) to (d) are diagrams illustrating a fourth example of the configuration of the insulating material according to the present embodiment. (a) to (c) are diagrams illustrating a fifth example of the configuration of the insulating material according to the present embodiment. (a) to (b) are diagrams illustrating a sixth example of the configuration of the insulating material according to the present embodiment. (a) to (d) are diagrams illustrating a seventh example of the configuration of the insulating material according to the present embodiment. (a) to (d) are diagrams illustrating a ninth example of the configuration of the insulating material according to the present embodiment. (a) to (d) are diagrams illustrating a tenth example of the configuration of the insulating material according to the present embodiment.

[0010] Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. <Description of the Configuration of Battery Group 1> FIG. 1 illustrates a battery group 1 included in a battery pack. The illustrated battery group 1 is formed by alternately stacking unit cells 2 and insulating materials 3. In addition to the battery group 1, the battery pack also includes busbar units connecting the positive and negative electrodes of the unit cells 2, a temperature measurement unit for measuring the temperature of the unit cells 2, a voltage detection unit for measuring the voltage of the unit cells 2, electrical wires, and a housing for accommodating these components. The unit cells 2 are, for example, lithium-ion secondary batteries, but are not limited to this type of secondary battery and may be, for example, nickel-metal hydride batteries. The insulating materials 3 are provided between adjacent unit cells 2 and are made of a thermally insulating material. This prevents heat transfer to adjacent unit cells 2 even if one unit cell 2 generates abnormal heat. The insulating materials 3 also function to insulate the unit cells 2 from each other, reducing the risk of short circuits.

[0011] <Explanation of the Structure of the Insulating Material 3> Figures 2(a) to 2(d) are diagrams showing a first example of the structure of the insulating material 3 according to this embodiment. Figures 2(a) to 2(d) also illustrate a manufacturing method for the insulating material 3. Of these, Figures 2(a) and 2(b) show a radiation-blocking member 31, a plate-shaped member 32, and a spacer 33 bonded together with an adhesive or the like. The radiation-blocking member 31 is sheet-shaped and functions to suppress radiation. The radiation-blocking member 31 prevents heat from being transferred to adjacent cells 2 even if one cell 2 generates abnormal heat. The radiation-blocking member 31 is, for example, aluminum foil. Using aluminum as the material for the radiation-blocking member 31 allows for the reflection of radiation. Other materials that can be used to suppress radiation include titanium oxide and carbon. Titanium oxide and carbon can absorb radiation, thereby suppressing it. The thickness of the radiation-blocking member 31 is preferably 0.1 mm or less. This allows the thickness of the heat insulating material 3 to be reduced while maintaining the function of the radiation blocking member 31.

[0012] The plate-shaped member 32 is a plate-shaped member having thermal insulation properties. The plate-shaped member 32 reduces thermal conductivity, preventing heat transfer to adjacent cells 2 even if one cell 2 generates abnormal heat. Furthermore, even if one cell 2 catches fire, the plate-shaped member 32 prevents the fire from spreading to the adjacent cell 2. From this perspective, the plate-shaped member 32 is preferably made of an inorganic non-metallic material. In this case, electrical insulation can be ensured and adjacent cells 2 can be prevented from short-circuiting. In this embodiment, a thin mica plate is used as the inorganic non-metallic material. The thin mica plate is primarily composed of mica, and is made flexible by adding silicon to the mica. When a thin mica plate is used as the plate-shaped member 32, the thickness is preferably 0.1 mm or more and 1.5 mm or less. By making the thickness of the plate-shaped member 32 0.1 mm or more, thermal insulation can be ensured. Furthermore, by setting the thickness of the plate-like member 32 to 1.5 mm or less, the thickness of the heat insulating material 3 can be made thin.

[0013] The spacer 33 is provided between the radiation blocking member 31 and the plate-like member 32, forming a gap therebetween. This gap improves thermal insulation and prevents heat transfer to adjacent cells 2 even if one cell 2 generates abnormal heat. The spacer 33 may be made of, for example, multiple mica pieces. The mica pieces may be made of the same components as the thin mica plate used as the plate-like member 32. The thickness of the spacer 33 is preferably 0.5 mm or more and 1.5 mm or less. One gap is the same thickness as the spacer 33. Setting the gap to 0.5 mm or more ensures thermal insulation. Setting the gap to 1.5 mm or less allows the thickness of the insulating material 3 to be thin. In this embodiment, two gaps are formed, so the gap in the insulating material 3 is twice the length described above.

[0014] 2(c) and 2(d) show that cushion members 34 are further attached to both main surfaces of the bonded radiation blocking member 31, plate-like member 32, and spacer 33 with an adhesive or the like.

[0015] The cushion member 34 absorbs the expansion of the cells 2. The cells 2 repeatedly expand and contract when charging and discharging. By providing the cushion member 34, the expansion of the cells 2 can be absorbed by the cushion member 34 contracting. This prevents the cells 2 from expanding, improving the durability of the cells 2. The cushion member 34 is made of, for example, polyurethane, epoxy resin, or silicone resin.

[0016] An example of a manufacturing method for the heat insulating material 3 shown in Figure 2 is as follows: A radiation blocking member 31, such as aluminum foil, is sandwiched between two plate-shaped members 32, each of which is a thin sheet of mica and has a thickness of 0.2 mm. At this time, a spacer 33 made of a mica piece is inserted between the radiation blocking member 31 and the plate-shaped member 32 to provide two gaps, and an adhesive is used to bond the radiation blocking member 31, spacer 33, and plate-shaped member 32 together (Figures 2(a) and 2(b)). Next, two cushion members 34 are bonded together using an adhesive, sandwiching the bonded radiation blocking member 31, spacer 33, and plate-shaped member 32 together (Figures 2(c) and 2(d)).

[0017] In this manner, the heat insulating material 3 shown in FIG. 2( d ) can be manufactured. In the heat insulating material 3 of FIG. 2( d ), the radiation blocking member 31, the plate-shaped member 32, and the cushion member 34 are arranged in this order in a direction intersecting the main surface of the radiation blocking member 31. Furthermore, spacers 33 are further provided between the radiation blocking member 31 and the plate-shaped member 12. Furthermore, the plate-shaped members 32 are arranged on both sides of the two main surfaces of the radiation blocking member 31 so as to sandwich the radiation blocking member 31, and the cushion members 34 are arranged on both sides of the two main surfaces of the plate-shaped member 32 so as to sandwich the plate-shaped member 32. In other words, in this case, one radiation blocking member 31 is sandwiched between the two radiation blocking members 31, and two plate-shaped members 32 and two cushion members 34 are arranged on both sides of the two main surfaces of the radiation blocking member 31. Furthermore, spacers 33 are arranged on both sides of the two main surfaces of the radiation blocking member 31 so as to sandwich the radiation blocking member 31. The spacer 33 is made up of a plurality of mica pieces, and the plate-like member 32 is a thin mica plate that is thinner than the spacer 33 .

[0018] In the above-described embodiment, the adhesive used for bonding the cells 2 may be, for example, an epoxy adhesive. The sizes of the radiation blocking member 31, the plate-like member 32, and the spacer 33 are adjusted to match the size of the cells 2, and may be, for example, 100 mm in height and 300 mm in depth. The manufactured insulating material 3 also preferably has the same size and a thickness of 5 mm to 6 mm. By making the insulating material 3 this thick, only a small space is required for its installation. Nevertheless, thermal insulation can be ensured, and even if a cell 2 generates abnormal heat, heating of adjacent cells can be suppressed.

[0019] 3(a) to 3(d) are diagrams showing a second example of the configuration of the heat insulating material 3 of this embodiment. The heat insulating material 3 of this embodiment is similar to the heat insulating material 3 shown in FIG. 2 except for the addition of a support member 35, as shown in FIG. 3(a). The support member 35 is disposed between the radiation blocking member 31 and the spacer 33. It supports the radiation blocking member 31. The support member 35 functions as a mount for the radiation blocking member 31. The support member 35 is a thin mica plate that is thinner than the spacer 33. In this case, the support member 35 can be the same as the plate-shaped member 32. That is, in this case, three thin mica plates are used as the plate-shaped member 32 and the support member 35.

[0020] The heat insulating material 3 shown in Figure 3 can be manufactured, for example, as follows: A radiation blocking member 31, such as aluminum foil, is attached to a support member 35, which is a thin mica plate and has a thickness of 0.2 mm, using an adhesive. The support member 35, to which the radiation blocking member 31 is attached, is sandwiched between two plate-shaped members 32, each of which is a thin mica plate and has a thickness of 0.2 mm. At this time, spacers 33 made of mica pieces are inserted between the radiation blocking member 31 and the plate-shaped members 32 to provide two gaps, and the support member 35, to which the radiation blocking member 31 is attached, the spacers 33, and the plate-shaped members 32 are attached using an adhesive (Figures 3(a)-(b)). Next, two cushion members 34 are attached using an adhesive, sandwiching the attached radiation blocking member 31, support member 35, spacers 33, and plate-shaped members 32 (Figures 3(c)-(d)).

[0021] 2 and 3, the spacers 33 are arranged on both sides of the two main surfaces of the radiation blocking member 31 so as to sandwich the radiation blocking member 31, but they may be arranged on only one side. FIGS. 4(a) to 4(d) are diagrams showing a third example of the configuration of the heat insulating material 3 of this embodiment. The heat insulating material 3 of this embodiment differs from the heat insulating material 3 shown in FIG. 2 in that, as shown in FIG. 4(a), the spacer 33 is arranged on one side of the main surface of the radiation blocking member 31 and not on the other side, but is otherwise similar. In this case, the thickness of the heat insulating material 3 can be made thinner. Furthermore, in this case, the plate-like member 32 on the right side of FIG. 4(a) also serves as a support member 35 that supports the radiation blocking member 31.

[0022] An example of a manufacturing method for the heat insulating material 3 shown in FIG. 4 is as follows. A radiation blocking member 31 is attached to one of two plate-shaped members 32, each of which is a thin mica plate and has a thickness of 0.2 mm. Instead of attaching the radiation blocking member 31, the radiation blocking member 31 may be coated on the plate-shaped member 32. This can be achieved, for example, by sputtering aluminum, titanium oxide, or carbon, the materials for the radiation blocking member 31, onto the plate-shaped member 32. The plate-shaped member 32 with the radiation blocking member 31 attached is then bonded to the other plate-shaped member 32, with the radiation blocking member 31 facing inward and a spacer 33 made of mica inserted to create a gap ( FIGS. 4( a)-(b) ). Next, two cushion members 34 are bonded together with adhesive, sandwiching the bonded radiation blocking member 31, spacer 33, and plate-shaped member 32 ( FIGS. 4( c)-(d) ).

[0023] 5(a) to 5(d) are diagrams showing a fourth example of the configuration of the thermal insulation material 3 of this embodiment. The thermal insulation material 3 of this embodiment differs from the thermal insulation material 3 shown in FIG. 4 in that, as shown in FIG. 5(a), it further includes a blanket-like thermal insulation material 36 that fills the gaps between the spacers 33 between the radiation-blocking member 31 and the plate-like member 32, but is otherwise similar. Here, "blanket-like" refers to a cotton-like structure made of fibers. Examples of fibers that can be used include ceramic fiber, alumina fiber, and mullite fiber. In this case, by filling the gaps between the spacers 33 with the thermal insulation material 36, the thermal insulation properties can be further improved.

[0024] An example of a manufacturing method for the heat insulating material 3 shown in FIG. 5 is as follows. A radiation blocking member 31 is attached to one of two plate-shaped members 32, each of which is a thin mica plate and has a thickness of 0.2 mm. Note that instead of attaching the radiation blocking member 31, the radiation blocking member 31 may be coated on the plate-shaped member 32. The plate-shaped member 32 to which the radiation blocking member 31 has been attached is then attached to the other plate-shaped member 32, with the radiation blocking member 31 facing inward and spacers 33 made of mica pieces inserted. At this time, a blanket-like heat insulating material 36 is packed between the mica pieces ( FIGS. 5( a) and 5(b) ). Next, two cushion members 34 are attached to each other with an adhesive, sandwiching the attached radiation blocking member 31, spacer 33, and plate-shaped member 32 ( FIGS. 5(c) and 5(d) ).

[0025] Although the spacer 33 is piece-shaped in FIGS. 2 to 5, this shape is not limiting. FIGS. 6(a) to 6(c) show a fifth example of the configuration of the heat insulating material 3 of this embodiment. The heat insulating material 3 of this embodiment differs from the heat insulating material 3 shown in FIG. 2 in that, as shown in FIG. 6(a), the spacer 33 is a frame arranged along the outer edge of the radiation blocking member 31, but is otherwise similar. In this case, the inside of the frame forms a gap between the radiation blocking member 31 and the plate-shaped member 32, improving the thermal insulation performance. The spacer 33 can be, for example, a thick mica plate. The thickness of the spacer 33 is preferably 0.5 mm or more and 1.5 mm or less. The thick mica plate can be made of the same composition as the thin mica plate used as the plate-shaped member 32. Note that, while one frame-shaped spacer 33 is used here, the piece-shaped spacer 33 described in FIGS. 2 to 5 may be added inside the frame.

[0026] An example of a manufacturing method for the heat insulating material 3 shown in Figure 6 is as follows. A radiation blocking member 31 such as aluminum foil is sandwiched between two plate-shaped members 32, each of which is a thin plate of mica and has a thickness of 0.2 mm. At this time, a spacer 33 made of a frame is inserted between the radiation blocking member 31 and the plate-shaped member 32 to provide two gaps, and an adhesive is used to bond the radiation blocking member 31, spacer 33, and plate-shaped member 32 together (Figures 6(a) and 6(b)). Next, two cushion members 34 are bonded together using an adhesive, sandwiching the bonded radiation blocking member 31, spacer 33, and plate-shaped member 32 (Figure 6(c)).

[0027] 2 to 6, the radiation blocking member 31, the spacer 33, the plate-shaped member 32, and the cushion member 34 are arranged in this order, with the cushion member 34 being disposed on the outermost side. However, this is not limiting. FIGS. 7(a) and 7(b) are diagrams showing a sixth example of the configuration of the heat insulating material 3 of this embodiment. In the heat insulating material 3 of this embodiment, the cushion member 34 is arranged between the radiation blocking member 31 and the plate-shaped member 32. In this case, the radiation blocking member 31, the cushion member 34, and the plate-shaped member 32 are arranged in this order, with the cushion member 34 being disposed on the inner side rather than the outermost side. The heat insulating material is then compressed and fixed so that its overall thickness is 1.0 mm or more and 5.0 mm or less. The cushion member 34 can be a blanket-shaped heat insulating material. In this case, the cushion member 34 can be the same as the blanket-shaped heat insulating material 36 described in FIG. 5. That is, the cushion member 34 can be a cotton-like material made of fibers such as ceramic fiber, alumina fiber, or mullite fiber. This allows the cushion member 34 to function as a heat insulator, improving heat insulation. In this case, it can also be said that the cushion member 34 is disposed on one side of the two main surfaces of the radiation blocking member, and not disposed on the other side.

[0028] The heat insulating material 3 shown in Figure 7 can be manufactured, for example, as follows: A radiation blocking member 31 is attached to one of two plate-shaped members 32, each of which is a thin mica plate and has a thickness of 0.2 mm. Note that instead of attaching the radiation blocking member 31, the radiation blocking member 31 may be formed by coating the plate-shaped member 32. The plate-shaped member 32 to which the radiation blocking member 31 has been attached is then attached to the other plate-shaped member 32, with the radiation blocking member 31 facing inward and with a cushion member 34 interposed between them (Figures 7(a) and (b)).

[0029] Although mica is used as the inorganic nonmetallic material for the plate-shaped member 32 in FIGS. 2 to 7 , this is not limiting. FIGS. 8( a) to 8(d) show a seventh example of the configuration of the heat insulating material 3 according to this embodiment. Of these, FIGS. 8(a) to 8(b) show that the radiation-blocking member 31 and the plate-shaped member 32 are bonded together using an adhesive or the like. The radiation-blocking member 31 is the same as described above. That is, the radiation-blocking member 31 is, for example, aluminum foil, titanium oxide, or carbon. The plate-shaped member 32 is also a heat-insulating member, as described above. However, in this embodiment, a fired inorganic nonmetallic material is used as the material for the plate-shaped member 32. Specifically, ceramics such as cordierite and diatomaceous earth are used as the material for the plate-shaped member 32. When ceramics are used for the plate-shaped member 32, the thickness is preferably 0.5 mm to 10 mm, more preferably 1 mm to 6 mm, and even more preferably 1.5 mm to 2 mm.

[0030] 8(c) and 8(d) show that cushion members 34 are further attached to both main surfaces of the attached radiation blocking member 31 and plate-like member 32 with an adhesive or the like.

[0031] The cushion member 34 is the same as that shown in Figures 2 to 6. That is, the cushion member 34 is made of, for example, polyurethane, epoxy resin, or silicone resin.

[0032] An example of a method for manufacturing the heat insulating material 3 shown in Figure 8 is as follows. A radiation blocking member 31 such as aluminum foil is sandwiched between two ceramic plate-like members 32 each having a thickness of 1 mm to 3 mm. At this time, an adhesive is used to bond the radiation blocking member 31 and the plate-like member 32 together (Figures 8(a) and 8(b)). Next, two cushion members 34 are bonded together using an adhesive, sandwiching the bonded radiation blocking member 31 and the plate-like member 32 between them (Figures 8(c) and 8(d)).

[0033] In this manner, the heat insulating material 3 shown in Fig. 8(d) can be manufactured. In the heat insulating material 3 of Fig. 8(d), the radiation blocking member 31, the plate-like member 32, and the cushion member 34 are arranged in this order in a direction intersecting the main surface of the radiation blocking member 31. However, there is no spacer 33.

[0034] On the other hand, a configuration in which a spacer 33 is provided may also be used. Figures 9(a) to 9(d) are diagrams showing a ninth example of the configuration of the heat insulating material 3 of this embodiment. The heat insulating material 3 of this embodiment differs from the heat insulating material 3 shown in Figure 8 in that it includes a spacer 33 as shown in Figure 9(a), but is otherwise similar. As in the above-described case, the spacer 33 is provided between the radiation blocking member 31 and the plate-shaped member 32, forming a gap between them. In this embodiment, the spacer 33 is an adhesive that bonds the radiation blocking member 31 and the plate-shaped member 32 in multiple locations. Elastic silicone adhesive or a highly heat-resistant cement-based inorganic adhesive can be used as the adhesive for forming the spacer 33. Note that when a silicone adhesive is used as the adhesive, its particularly excellent elasticity allows it to also function as a cushion member 34. In this case, as shown in Figure 9(a), adhesive is applied in multiple disc-shaped locations on the main surface of the plate-shaped member 32 facing the radiation blocking member 31, and is bonded to the radiation blocking member 31. In other words, the adhesive not only bonds the radiation blocking member 31 and the plate-like member 32 together, but also functions as the spacer 33. This forms a gap between the radiation blocking member 31 and the plate-like member 32, and this gap improves the thermal insulation, as in the case described above. This gap can be 0.5 mm or more and 1.5 mm or less.

[0035] An example of a manufacturing method for the heat insulating material 3 shown in Figure 9 is as follows. Spacers 33 are formed with an adhesive on two 3 mm-thick ceramic plate-like members 32. A radiation blocking member 31 such as aluminum foil is sandwiched between the two plate-like members 32, with the sides with the spacers 33 facing inward. At this time, the radiation blocking member 31 and the plate-like members 32 are bonded together using an adhesive, which is the spacer 33 (Figures 9(a)-(b)). Next, two cushion members 34 are bonded together using an adhesive, sandwiching the bonded radiation blocking member 31, spacers 33, and plate-like members 32 (Figures 9(c)-(d)).

[0036] 10(a) to 10(d) are diagrams showing a tenth example of the configuration of the thermal insulation material 3 of this embodiment. Compared to the thermal insulation material 3 of FIG. 9, the thermal insulation material 3 of this embodiment has through holes 32h formed by dividing the plate-shaped member 32 with partition walls made of an inorganic non-metallic material, as shown in FIG. 10(a). The through holes 32h are formed along the main surface of the plate-shaped member 32 and penetrate in the vertical direction in the figure. In this case, the through holes 32h can also be said to be multiple rectangular parallelepiped-shaped cells. The provision of the through holes 32h improves the thermal insulation properties of the plate-shaped member 32.

[0037] The thickness of the partition walls is preferably 50 μm or more, more preferably 60 μm or more, and even more preferably 70 μm or more, from the viewpoint of ensuring the strength of the plate-like member 32. Furthermore, the thickness of the partition walls is preferably 200 μm or less, more preferably 130 μm or less, and even more preferably 100 μm or less, from the viewpoint of suppressing heat conduction to the plate-like member 32. The thickness of the outer periphery of the plate-like member 32 is preferably thicker than the thickness of the partition walls, and can be, for example, 400 μm.

[0038] Furthermore, in order to ensure the strength of the plate-like member 32 and further improve the heat insulation, a filler may be filled into the through-holes 32h. The filler may be, for example, an aerosol, more specifically, fumed silica, mica powder, or the like. Such fillers have a lower thermal conductivity than air, so providing the filler in the through-holes 32h reduces the thermal conductivity compared to a hollow state, making it more difficult for heat to be transmitted.

[0039] The heat insulating material 3 shown in Figure 10 can be manufactured, for example, as follows. A radiation blocking member 31 is attached to a single plate-shaped member 32 made of ceramics and having a thickness of 3 mm, with a through hole 32h (Figures 10(a) and 10(b)). Note that instead of attaching the radiation blocking member 31, the radiation blocking member 31 may be formed by coating the plate-shaped member 32. Next, two cushion members 34 are attached to each other with an adhesive, sandwiching the attached radiation blocking member 31 and plate-shaped member 32 (Figures 10(c) and 10(d)). In this case, it can also be said that the plate-shaped member 32 is disposed on one of the two main surfaces of the radiation blocking member 31, and not on the other.

[0040] The heat insulating material 3 described above in detail has one radiation blocking member 31, but it may have multiple radiation blocking members 31. In this case, a plurality of radiation blocking members 31 may be disposed, or the heat insulating material 3 may be formed by coating the radiation blocking members 31 on both sides of the two main surfaces of the plate-shaped member 32.

[0041] The manufacturing method of the heat insulating material 3 described above in detail can be considered to include the steps of bonding together the sheet-shaped radiation blocking member 31 that blocks radiation and the plate-shaped member 32 that has heat insulating properties and is disposed on at least one of the two main surfaces of the radiation blocking member 31, and bonding the cushion member 34 that absorbs the expansion of the cells 2 to the same side and / or the opposite side of the two main surfaces of the radiation blocking member 31. Note that these two steps can be performed separately or simultaneously. In other words, the radiation blocking member 31, the plate-shaped member 32, and the cushion member 34 are bonded together in the same step using an adhesive.

[0042] 2, for example, in the case of a thermal insulation material 3 that includes spacers 33, the spacers 33 are inserted in the step of bonding the radiation blocking member 31 and the plate-like member 32 together to form a gap between the radiation blocking member 31 and the plate-like member 32. Furthermore, for example, in the case of a thermal insulation material 3 that further includes a blanket-like thermal insulation material 36, for example, as shown in Fig. 5, the blanket-like thermal insulation material 36 is inserted to fill the gap between the spacers 33 when bonding the radiation blocking member 31 and the plate-like member 32 together. And, for example, in the case of a thermal insulation material 3 that includes a support member 35 as shown in Fig. 3, the method further includes a step of bonding the support member 35 that supports the radiation blocking member to the radiation blocking member 31 before the step of bonding the radiation blocking member 31 and the plate-like member 32 together.

[0043] <Explanation of Effects> According to the embodiment described above, it is possible to provide a heat insulating material 3 and a method for manufacturing the heat insulating material 3 that can suppress heating of adjacent cells 2 when a cell 2 abnormally generates heat, compared to a case where the configuration of the present invention is not provided. As a result, even when a cell 2 experiences thermal runaway, for example, the heat insulating material 3 of this embodiment has a heat insulating function that makes it difficult for heat to be transferred to adjacent cells 2. When a cell 2 experiences thermal runaway, the temperature may reach 800°C or higher, for example. Even in this case, it is possible to slow down the transfer of heat, and when the battery pack is used in a vehicle, for example, it is possible to ensure that the driver has time to evacuate.

[0044] Particularly at high temperatures above 800°C, radiation is proportional to the fourth power of absolute temperature, so the impact of radiant heat becomes significant, accounting for 30% to 40% of thermal conduction, calculated. In this embodiment, the provision of the radiation-blocking member 31 can suppress heat transfer between cells 2 due to radiant heat when a cell 2 abnormally heats up. This also prevents fire from spreading to adjacent cells 2. The radiation-blocking member 31 has a thickness of, for example, 0.1 mm or less, yet still functions as intended. Furthermore, particularly when a thin mica plate is used as the plate-like member 32, the thickness is, for example, 0.1 mm to 1.5 mm, yet still provides thermal insulation. Spacers 33 can be installed to further improve thermal insulation. The gap formed by the spacers 33 is, for example, 0.5 mm to 1.5 mm, without significantly increasing the thickness. This allows the overall thickness of the thermal insulation material 3 to be thin, allowing installation in a narrow space while still maintaining thermal insulation. Furthermore, when the plate-like member 32 is made of an inorganic non-metallic material containing , it is lightweight, and the weight of the heat insulating material 3 and the unit cells 2 can be reduced.

[0045] Furthermore, since the heat insulating material 3 includes the cushion members 34, the expansion of the cells 2 can be absorbed by the cushion members 34 contracting.

[0046] Example 1 The heat insulating material 3 shown in Fig. 2 was manufactured and heated in an air atmosphere in an electric furnace at a temperature of 800°C for 5 minutes. As a result, the heat insulating material 3 did not burn.

[0047] (Example 2) The thermal insulation material 3 shown in Figure 2 was manufactured, and the thermal conductivity in the thickness direction was measured. The thermal conductivity was 0.07 to 0.08 [W / (mK)]. When a mica sheet was used as a conventional thermal insulation material, the thermal conductivity was 0.23 [W / (mK)], and the thermal conductivity was reduced to approximately one-third. In addition, the weight was reduced to approximately one-seventh. Furthermore, the manufacturing cost was reduced to approximately one-fifth.

[0048] Example 3 The battery group 1 shown in Fig. 1 was manufactured using the heat insulating material 3 shown in Fig. 2, and actual charging and discharging were performed. During this process, the cells 2 expanded and contracted, but the expansion of the cells 2 was absorbed by the contraction of the cushion members 34.

[0049] Although the present embodiment has been described above, the technical scope of the present invention is not limited to the scope of the above embodiment. It is clear from the claims that various modifications and improvements to the above embodiment are also included in the technical scope of the present invention.

[0050] REFERENCE SIGNS LIST 1 battery group, 2 electric cell, 3 heat insulating material, 31 radiation shielding member, 32 plate-shaped member, 32h through-hole, 33 spacer, 34 cushion member, 35 support member, 36 heat insulating material

Claims

1. A thermal insulation material used in a battery pack including a group of batteries in which unit cells and thermal insulation materials are alternately stacked, the thermal insulation material comprising: a sheet-like radiation blocking member that suppresses radiation; a plate-like member that is arranged on at least one side of the two main surfaces of the radiation blocking member and has thermal insulation properties; and a cushion member that is arranged on the same side and / or the opposite side of the one side of the two main surfaces of the radiation blocking member and absorbs the expansion of the unit cells when they expand.

2. The heat insulating material according to claim 1, wherein the radiation blocking member, the plate-like member and the cushion member are arranged in this order in a direction intersecting the main surface.

3. The heat insulating material described in claim 2, wherein the plate-like members are arranged on both sides of the two main surfaces of the radiation blocking member so as to sandwich the radiation blocking member, and the cushion members are arranged on both sides of the two main surfaces of the plate-like member so as to sandwich the plate-like member.

4. The heat insulating material according to claim 2, further comprising a spacer provided between the radiation blocking member and the plate-like member to form a gap.

5. The heat insulating material according to claim 4, wherein the spacer is made up of a plurality of pieces whose main component is mica, and the plate-like members are made mainly of mica and thinner than the spacers.

6. The heat insulating material according to claim 5, further comprising a support member between the radiation blocking member and the spacer, which supports the radiation blocking member and is made primarily of mica and is thinner than the spacer.

7. The heat insulating material according to claim 4, further comprising a blanket-shaped heat insulating material filling the gap between the spacers between the radiation blocking member and the plate-shaped member.

8. The heat insulating material according to claim 4, wherein at least a portion of the spacer is a frame disposed along the outer edge of the radiation blocking member.

9. The heat insulating material according to claim 4, wherein the spacer is an adhesive that bonds the radiation blocking member and the plate-like member in a plurality of dispersed locations.

10. The heat insulating material according to claim 1, wherein the plate-like members are made of an inorganic non-metallic material.

11. The heat insulating material according to claim 10, wherein the plate-like members are thin plates of mica.

12. The heat insulating material according to claim 1, wherein the cushion member is disposed between the radiation blocking member and the plate-like member.

13. The heat insulating material according to claim 12, wherein the cushion member is a blanket-type heat insulating material.

14. A method for manufacturing an insulating material used in a battery pack including a group of batteries in which unit cells and insulating materials are alternately stacked, the method comprising the steps of: bonding together a sheet-like radiation blocking member that suppresses radiation and a plate-like member that has insulating properties and is arranged on at least one side of two main surfaces of the radiation blocking member; and bonding a cushion member that absorbs the expansion of the unit cells to the same side and / or the opposite side of the one side of the two main surfaces of the radiation blocking member.

15. A method for manufacturing a heat insulating material as described in claim 14, wherein a spacer is inserted to form a gap between the radiation blocking member and the plate-like member in the step of bonding the radiation blocking member and the plate-like member.

16. The method for manufacturing a heat insulating material according to claim 15, wherein a blanket-shaped heat insulating material is inserted to fill the gaps between the spacers when the radiation blocking member and the plate-shaped member are bonded together.

17. A method for manufacturing a heat insulating material as described in claim 14, further comprising the step of attaching a support member for supporting the radiation blocking member to the radiation blocking member before the step of attaching the radiation blocking member to the plate-shaped member.

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