JP2023035097A - Thermal insulation elastic member - Google Patents

Abstract

To provide an elastic member that can suppress the heat transfer between battery cells by securing a space between the adjacent battery cells and making the heat insulating sheet work even when the temperature of a certain battery cell rises.SOLUTION: A thermal insulation elastic member 30 is placed between two adjacent battery cells, and includes a heat insulating sheet 40, a plurality of elastic bodies 50 and 51 arranged on one side of the heat insulating sheet 40 at predetermined intervals, and a regulating body 60 that is disposed between at least the elastic bodies 50 and 51 on one side of the heat insulating sheet 40, is made of a material different from that of the elastic bodies 50 and 51, and has flame retardant, and whose thermal conductivity is equal to or smaller than the thermal conductivity of the elastic bodies 50 and 51.SELECTED DRAWING: Figure 2

Description

TECHNICAL FIELD The present disclosure relates to a heat insulating elastic member arranged between adjacent battery cells in a battery pack containing a plurality of battery cells.

Hybrid vehicles and electric vehicles are equipped with a battery pack containing a plurality of battery cells. In a battery pack, a battery module formed by stacking a plurality of battery cells is housed in a housing while being fixed by fastening members from both sides in the stacking direction. If the temperature of one battery cell rises for any reason, this heat can be transferred to adjacent battery cells, causing thermal chain reactions that can lead to catastrophic events. Heat insulation is placed between adjacent battery cells to avoid heat chaining.

For example, U.S. Pat. No. 6,300,009 describes a multilayer sheet that is placed between adjacent battery cells. As shown in FIG. 3 of Patent Document 1, the multilayer sheet is formed by laminating a first thermal conductive sheet/a heat insulating sheet/rubber sheet/a thermal insulating sheet/first thermal conductive sheet in the thickness direction. The first thermally conductive sheet is made of metal or the like having high thermal conductivity, and has a heat dissipation function. Patent Literature 2 describes a partition member arranged between adjacent battery cells. The partition member has a base material that melts when the temperature rises, and a thermosetting resin spacer embedded in the base material.

Japanese Patent Application Laid-Open No. 2021-99940 JP 2010-97693 A

In order to improve the heat insulating performance of the heat insulating material, the thickness should be increased. However, when arranging in a limited space between battery cells in a battery pack, it is necessary to minimize the thickness of the heat insulating material. Therefore, the heat insulating material is required to have both thinness and heat insulating performance.

Adjacent battery cells are separated from each other by heat insulating material, which is made of rubber to prevent the battery cells from shifting due to vibrations when the vehicle is running, and to follow the expansion and contraction of the battery cells due to charging and discharging. Cushioning material may be interposed. In this case, a heat insulating material and a cushioning material are laminated and arranged between the battery cells. For example, when the temperature of the battery cells rises to a high temperature of several hundred degrees Celsius, the rubber cushioning material melts and disappears. When the cushioning material disappears, the heated and expanded battery cells come into contact with the insulating material, narrowing the gap between the battery cells normally held by the insulating material and the cushioning material. As the space between battery cells becomes narrower, the heat insulating effect is reduced accordingly. In this state, if the heat transfer must be suppressed only by the heat insulating material, there is a limit to the heat insulating performance without changing the thickness or material. Also, if the molten rubber material adheres to a member responsible for heat dissipation, such as a cooling pipe arranged in the battery pack, there is a risk of impeding the cooling function.

The multilayer sheet described in Patent Document 1 also has a rubber sheet. However, in the multilayer sheet, heat insulating sheets are arranged on both sides in the thickness direction of the rubber sheet. Here, the size of the rubber sheet and the heat insulating sheet are the same. That is, both sides in the thickness direction of the rubber sheet are covered with heat insulating sheets. Furthermore, first thermally conductive sheets with excellent heat dissipation are also arranged on both sides in the thickness direction of the heat insulating sheet. Therefore, even if the temperature of the battery cell rises, the heat is less likely to be transferred to the rubber sheet. In paragraph [0036] of Patent Document 1, "The rubber sheet 13 is made of a highly heat-resistant material that can maintain its shape without being melted or decomposed by heat transmitted through the first heat conductive sheet 11 and the heat insulating sheet 12. It is preferred to be constructed." In the multilayer sheet, it is not assumed that the rubber sheet will melt. On the other hand, in the partition member of Patent Document 2, the base material is made of wax or the like, and melts when the temperature of the battery cells rises. As described in paragraph [0007] of Patent Document 2, in the partition member, the heat of fusion when the base material melts is used to suppress the heat transfer between the battery cells. Since the spacers embedded in the base material remain between the battery cells even after the base material melts, the intervals between the battery cells are maintained. However, the spacer is made of thermosetting resin, and the flame retardancy and thermal conductivity of the spacer are not taken into consideration. Therefore, just disposing spacers between battery cells does not provide sufficient heat insulating performance.

The present disclosure has been made in view of such circumstances, and is intended to ensure a space between adjacent battery cells to exhibit heat insulating properties by a heat insulating sheet even if the temperature of a certain battery cell rises. An object of the present invention is to provide a heat insulating elastic member capable of suppressing heat transfer between battery cells.

In order to solve the above problems, the heat insulating elastic member of the present disclosure is a heat insulating elastic member that is arranged between adjacent battery cells, and comprises a heat insulating sheet and a heat insulating sheet arranged on one side of the heat insulating sheet at a predetermined interval. a plurality of elastic bodies, arranged between at least the elastic bodies on one side of the heat insulating sheet, made of a material different from the elastic bodies, having flame retardancy, and having thermal conductivity equal to the thermal conductivity of the elastic bodies and a regulating body equal to or smaller than .

In the heat insulating elastic member of the present disclosure, a plurality of elastic bodies and a regulating body are arranged on one side of the heat insulating sheet. The elastic body has a cushioning property and plays a role of suppressing displacement of the battery cell during running of the vehicle and absorbing deformation due to expansion and contraction of the battery cell during charging and discharging. The regulating body is arranged between the elastic bodies. The regulating body is made of a material different from that of the elastic body and has flame resistance. Therefore, even if the temperature of the battery cells rises and the elastic body melts, the regulating body remains, thereby suppressing the expansion of the battery cells and preventing the gaps between the battery cells and between the battery cells and the heat insulating sheet. can be maintained. In addition, since the thermal conductivity of the regulating body is equal to or smaller than that of the elastic body, the regulating body can be expected to have a heat insulating effect. By interposing the regulating body in this manner, the gap between the battery cells can be maintained, and the heat insulating effect of the regulating body and the heat insulating sheet can be fully exhibited.

Therefore, according to the heat insulating elastic member of the present disclosure, heat transfer between adjacent battery cells can be suppressed without increasing the thickness of the heat insulating sheet or increasing the amount of heat insulating material. Thereby, the cost can be reduced. In addition, even if the heat insulating sheet is flexible and lacks self-supporting properties, the restricting body serves as a skeleton, so that the heat insulating elastic member as a whole exhibits self-supporting properties. As a result, workability during assembly can be improved. Furthermore, by arranging the regulating body below the elastic body or arranging it in a frame shape around the elastic body, it is possible to suppress the outflow of the melted elastic body. As a result, it is possible to prevent the melted elastic body from adhering to members responsible for heat dissipation, such as cooling pipes arranged in the battery pack.

It is a cross-sectional schematic diagram of the battery pack in which the thermal insulation elastic member of 1st embodiment is arrange|positioned. It is a perspective view of the thermal insulation elastic member of 1st embodiment. It is thickness direction sectional drawing of the same heat insulation elastic member. FIG. 4 is a perspective view of a heat insulating elastic member of a second embodiment; It is thickness direction sectional drawing of the same heat insulation elastic member. FIG. 11 is a perspective view of a heat insulating elastic member of a third embodiment; It is thickness direction sectional drawing of the same heat insulation elastic member.

<First Embodiment>
[composition]
First, the configuration of the heat insulating elastic member of the first embodiment will be described. FIG. 1 shows a schematic cross-sectional view of a battery pack in which the heat insulating elastic member of the first embodiment is arranged. FIG. 2 shows a perspective view of the heat insulating elastic member of the first embodiment. FIG. 3 shows a cross-sectional view taken along line III-III of FIG. 2 (a cross-sectional view of the heat insulating elastic member in the thickness direction). Regarding the orientation in the figure, the direction in which the battery cells are arranged (thickness direction and stacking direction of each member) is the X direction, and one of the two directions perpendicular to the X direction, which is the longitudinal direction of the battery cells, is the Y direction, and the short direction is the Y direction. The other hand direction (the direction corresponding to the direction of gravity) is the Z direction (the same applies to the following drawings). As shown in FIG. 1 , the battery pack 1 has a housing 10 , a plurality of battery cells 2 and a heat insulating elastic member 30 .

The housing 10 is made of metal and has a box shape. The plurality of battery cells 2 consist of lithium ion batteries. Each of the plurality of battery cells 2 has a rectangular thin plate shape and is stacked in the thickness direction (X direction). The heat insulating elastic member 30 is arranged between adjacent battery cells 2 . As shown in FIGS. 2 and 3, the heat insulating elastic member 30 has a heat insulating sheet 40, two elastic bodies 50 and 51, and a regulating body 60. As shown in FIGS.

The heat insulating sheet 40 has a rectangular sheet shape with a thickness of 2 mm. The heat insulating sheet 40 has a sheet body 41 and a cover layer 42 . The sheet body 41 has a heat insulating layer and a base material that supports it. The heat insulating layer has silica airgel, and silica particles and gypsum as binders. The substrate is made of glass cloth. The heat insulating layer is formed by applying a slurry composition containing silica airgel to a substrate. A part of the heat insulating layer is impregnated into the pores between the glass fibers forming the base material. The cover layer 42 is made of a resin film and covers the surface of the sheet body 41 . The back surface of the sheet body 41 that is not covered with the cover layer 42 is in contact with the battery cells 2 .

The two elastic bodies 50 and 51 are arranged on one side of the heat insulating sheet 40, namely one of the YZ planes. The two elastic bodies 50 and 51 are adhered to the cover layer 42 of the heat insulating sheet 40 with double-sided tape (not shown). The two elastic bodies 50 and 51 each extend in the Y direction (longitudinal direction of the heat insulating sheet 40), and are arranged parallel to each other with a predetermined spacing in the Z direction (lateral direction of the heat insulating sheet 40). there is The two elastic bodies 50, 51 are the same in material, shape and size. Therefore, only one elastic body 50 will be described here. The elastic body 50 is made of a crosslinked rubber composition having ethylene-propylene-diene rubber (EPDM). The elastic body 50 has a flat plate portion 500 and two rib portions 501 . Each of the two protrusions 501 extends in the Y direction. The two ridges 501 are arranged parallel to each other in the Z direction with the flat plate 500 interposed therebetween. By alternately arranging the flat plate portions 500 and the ridge portions 501 in the Z direction, the surface of the elastic body 50 on the battery cell 2 side has an uneven shape. The height of the two protrusions 501 (maximum thickness of the elastic body 50) is 6 mm in a non-compressed state. The two protrusions 501 are in elastic contact with adjacent battery cells 2 .

The regulating body 60 is also arranged on the YZ plane of the heat insulating sheet 40 where the two elastic bodies 50 and 51 are arranged. The regulation body 60 is adhered to the cover layer 42 of the heat insulating sheet 40 with a double-sided tape (not shown). The restricting body 60 has a strip shape and is arranged between the two elastic bodies 50 and 51 . The restrictor 60 extends in the Y direction at an intermediate position in the Z direction. The thickness of the regulation body 60 is 2 mm. The regulation body 60 is made of flame-retardant heat-insulating cloth. The flame-retardant heat-insulating cloth is the same as the sheet body 41 of the heat-insulating sheet 40, and has a heat-insulating layer containing silica airgel, silica particles and gypsum as binders, and a glass cloth that supports it. there is Part of the heat insulating layer is impregnated into the pores between the fibers of the glass cloth. Glass cloth is included in the concept of "cloth made of inorganic fibers" in the present disclosure. The regulation body 60 has flame retardancy, and the thermal conductivity of the regulation body 60 is smaller than the thermal conductivity of the elastic bodies 50 and 51 .

[Effect]
Next, the effects of the heat insulating elastic member of this embodiment will be described. In the insulating elastic member 30 , two elastic bodies 50 and 51 and a restricting body 60 are arranged on one side of the insulating sheet 40 . The two elastic bodies 50 and 51 are in elastic contact with the battery cell 2 and repeat compression and restoration following expansion and contraction of the battery cell 2 during charging and discharging. As a result, displacement of the battery cells 2 during running of the vehicle is suppressed, and deformation of the battery cells 2 due to charge/discharge is absorbed. Also, since the elastic body 50 has two ridges 501 (the same applies to the elastic body 51), the cross-sectional area in the XZ direction is smaller than when the elastic body 50 is formed in a rectangular parallelepiped shape with the same thickness. Therefore, the elastic bodies 50 and 51 are easily deformed by compression, and have excellent followability to the battery cell 2 . Both of the two elastic bodies 50 and 51 linearly extend in one direction. Therefore, it is easy to manufacture by extrusion. The two elastic bodies 50 and 51 are arranged symmetrically in the Z direction with the restricting body 60 interposed therebetween. Therefore, the deformation of the adjacent battery cells 2 can be absorbed in a well-balanced manner, and problems such as tilting of the battery cells 2 during charging and discharging are less likely to occur.

The regulating body 60 is arranged between the two elastic bodies 50 and 51 . Unlike the two elastic bodies 50 and 51, the regulating body 60 is made of flame-retardant heat-insulating cloth. Therefore, even if the temperature of the adjacent battery cells 2 rises, the regulator 60 is less likely to burn and less likely to transmit heat. In addition, the flame-retardant heat-insulating cloth is formed by supporting a heat-insulating layer containing silica airgel or the like on a glass cloth. In the thermal insulation layer, the binders that bind components such as silica airgel are silica particles and gypsum. Therefore, even at high temperatures, decomposition and deterioration of the binder are unlikely to occur, and the heat insulating structure is maintained. In addition, the restricting body 60 is relatively hard and does not easily collapse even when compressed by the expansion of the battery cell 2 . Therefore, even if the temperature of the battery cell 2 rises and the two elastic bodies 50 and 51 melt, the regulation body 60 remains. As a result, expansion of the battery cells 2 is suppressed, and the gap between the battery cells 2 and the heat insulating sheet 40 can be maintained. The restricting body 60 is arranged so as to separate the two elastic bodies 50 and 51 . Therefore, it also has the effect of blocking the molten material of the elastic bodies 50 and 51 . Here, since the regulating body 60 has glass cloth, a part of the molten material of the elastic bodies 50 and 51 impregnates the pores between the glass fibers. Further, the restricting body 60 is arranged in a strip shape at an intermediate position in the Z direction. The battery cell 2 tends to expand near the center when the temperature rises. Therefore, when the regulation body 60 is arranged so as to include the central region on one side of the heat insulating sheet 40 , it is effective in maintaining the gap between the battery cells 2 and the heat insulating sheet 40 . Thus, according to the heat insulating elastic member 30, the heat insulating effect of the regulating body 60 and the heat insulating sheet 40 can be fully exhibited.

The thickness of the heat insulating elastic member 30 is 8 mm. The heat-insulating elastic member 30 can suppress heat transfer between the adjacent battery cells 2 without increasing the thickness of the heat-insulating sheet 40 or increasing the amount of heat-insulating material. Thereby, the cost can be reduced. In addition, although the heat insulating sheet 40 is thin and lacks self-supporting properties, the regulation body 60 serves as a framework, so that the heat insulating elastic member 30 as a whole exhibits self-supporting properties. As a result, workability during assembly can be improved. A sheet body 41 of the heat insulating sheet 40 is covered with a cover layer 42 . As a result, fluffing of the glass fiber and powder falling off of the silica airgel are suppressed, and workability and the like are improved. In addition, impregnation of the molten material of the elastic bodies 50 and 51 into the glass cloth of the sheet body 41 can be suppressed.

<Second embodiment>
[composition]
The difference between the heat-insulating elastic member of this embodiment and the heat-insulating elastic member of the first embodiment lies in the arrangement of the elastic body and the regulating body. Here, mainly the points of difference will be explained. FIG. 4 shows a perspective view of the heat insulating elastic member of this embodiment. FIG. 5 shows a cross-sectional view taken along the line VV in FIG. 4 (cross-sectional view of the heat insulating elastic member in the thickness direction). In FIGS. 4 and 5, the same members as in the first embodiment are denoted by the same reference numerals. As shown in FIGS. 4 and 5, the heat insulating elastic member 31 has a heat insulating sheet 40, two elastic bodies 52 and 53, and a regulating body 61. As shown in FIGS.

The two elastic bodies 52 and 53 are arranged on one side of the heat insulating sheet 40, that is, one of the YZ planes. The two elastic bodies 52 and 53 are adhered to the cover layer 42 of the heat insulating sheet 40 with double-sided tape (not shown). The two elastic bodies 52 and 53 are arranged one by one on both sides in the Y direction (longitudinal direction of the heat insulating sheet 40) with a predetermined gap therebetween. The two elastic bodies 52, 53 are the same in material, shape and size. Therefore, only one elastic body 52 will be described here. The elastic body 52 is made of a crosslinked rubber composition having EPDM. The elastic body 52 has a flat plate portion 520 and six rib portions 521 . Each of the six ridges 521 extends in the Z direction. The six ridges 521 are arranged parallel to each other in the Z direction with the flat plate 520 interposed therebetween. By alternately arranging the flat plate portions 520 and the ridge portions 521 in the Y direction, the surface of the elastic body 52 on the battery cell side is uneven. The height of the six ridges 521 (the maximum thickness of the elastic body 52) is 6 mm in a non-compressed state. The six protrusions 521 are in elastic contact with adjacent battery cells.

The regulating body 61 is also arranged on the YZ plane of the heat insulating sheet 40 where the two elastic bodies 52 and 53 are arranged. The regulation body 61 is adhered to the cover layer 42 of the heat insulating sheet 40 with a double-sided tape (not shown). The restricting body 61 has a rectangular plate shape and is arranged between the two elastic bodies 52 and 53 . The regulating body 61 is arranged in the middle area when one side of the heat insulating sheet 40 is divided into approximately three parts in the Y direction. The thickness of the regulation body 61 is 2 mm. The regulating body 61 is made of the same flame-retardant heat-insulating cloth as the regulating body 60 of the first embodiment.

[Effect]
Next, the effects of the heat insulating elastic member of this embodiment will be described. The heat-insulating elastic member of this embodiment and the heat-insulating elastic member of the first embodiment have similar operational effects with respect to portions having common configurations. According to the heat insulating elastic member 31, the two elastic bodies 52 and 53 are arranged symmetrically in the Y direction with the regulating body 61 interposed therebetween. Therefore, the deformation of the adjacent battery cells can be absorbed in a well-balanced manner, and problems such as tilting of the battery cells during charging and discharging are less likely to occur. The regulating body 61 is arranged over the entire intermediate position in the Y direction. Therefore, even when the temperature of the battery cell rises and the vicinity of the center expands, it is effective to maintain the gap between the battery cell and the heat insulating sheet 40 .

<Third embodiment>
[composition]
The difference between the heat-insulating elastic member of this embodiment and the heat-insulating elastic member of the first embodiment is the configuration of the heat-insulating sheet, the shape of the elastic body, and the exterior body. Here, mainly the points of difference will be explained. FIG. 6 shows a perspective view of the heat insulating elastic member of this embodiment. FIG. 7 shows a cross-sectional view taken along line VII-VII of FIG. 6 (a cross-sectional view of the heat insulating elastic member in the thickness direction). In FIG. 6, the exterior body is omitted for convenience of explanation. 6 and 7, the same members as in the first embodiment are denoted by the same reference numerals. As shown in FIGS. 6 and 7 , the heat insulating elastic member 32 has a heat insulating sheet 43 , two elastic bodies 54 and 55 , a regulating body 60 and an exterior body 44 .

The heat insulating sheet 43 has a rectangular sheet shape with a thickness of 2 mm. The heat insulating sheet 43 is the same as the sheet body 41 of the first embodiment, and is formed by supporting a heat insulating layer containing silica airgel or the like on a substrate made of glass cloth.

The two elastic bodies 54 and 55 are arranged on one side of the heat insulating sheet 43, that is, one of the YZ planes. Each of the two elastic bodies 54 and 55 has a flat plate shape extending in the Y direction (longitudinal direction of the heat insulating sheet 40). The two elastic bodies 54 and 55 are arranged in parallel with each other with a predetermined gap in the Z direction (transverse direction of the heat insulating sheet 40). The two elastic bodies 54, 55 are the same in material, shape and size. Therefore, only one elastic body 54 will be described here. The elastic body 54 is made of a crosslinked rubber composition containing EPDM. The elastic body 54 has a hollow portion 540 and a pair of lightening portions 541 . The hollow portion 540 is arranged in the central portion inside the elastic body 54 and extends in the Y direction. The pair of lightening portions 541 are arranged on both Z-direction side surfaces of the elastic body 54 and extend in the Y-direction. The thickness of the elastic body 54 is 6 mm in an uncompressed state. The surface of the elastic body 54 on the battery cell side is in elastic contact with the adjacent battery cell.

The regulating body 60 is also arranged on the YZ plane of the heat insulating sheet 43 on which the two elastic bodies 54 and 55 are arranged. The restricting body 60 has a strip shape and is arranged between the two elastic bodies 54 and 55 . The restrictor 60 extends in the Y direction at an intermediate position in the Z direction. The regulating body 60 is made of flame-retardant heat-insulating cloth with a thickness of 2 mm.

The exterior body 44 is made of a resin film and covers the entire surface of the laminate composed of the heat insulating sheet 43 , the elastic bodies 54 and 55 and the regulation body 60 . The heat-insulating elastic member 32 is manufactured by housing the laminate in a bag-shaped resin film, degassing the film, and then thermally compressing the opening of the film. The elastic bodies 54 and 55 and the regulation body 60 are fixed to the heat insulating sheet 43 by the exterior body 44 and integrated.

[Effect]
Next, the effects of the heat insulating elastic member of this embodiment will be described. The heat-insulating elastic member of this embodiment and the heat-insulating elastic member of the first embodiment have similar operational effects with respect to portions having common configurations. In the heat-insulating elastic member 32, the elastic body 54 has a hollow portion 540 and a pair of lightening portions 541 (the same applies to the elastic body 55). For this reason, the cross-sectional area in the XZ direction is smaller than in the case of forming a solid rectangular parallelepiped with the same thickness. Therefore, the elastic bodies 54 and 55 are easily deformed by compression and have excellent followability to the battery cells. The heat-insulating elastic member 32 has an exterior body 44 , and the elastic bodies 54 and 55 and the regulating body 60 are fixed to and integrated with the heat-insulating sheet 43 by the exterior body 44 . Therefore, an adhesive agent, a pressure-sensitive adhesive, or the like for adhering each member is not required. In addition, since the heat insulating sheet 43, the elastic bodies 54 and 55, and the regulating body 60 are enclosed in the exterior body 44, the handleability and workability are excellent. In addition, since there is no need to consider fluffing of the glass fiber and falling powder of the silica airgel, unlike the first and second embodiments, the cover layer in the heat insulating sheet is not required.

<Other embodiments>
Three modes for carrying out the heat insulating elastic member of the present disclosure have been described above. However, the embodiment is not limited to the form described above. The insulating elastic member of the present disclosure can be embodied in various forms with modifications, improvements, etc. that can be made by those skilled in the art.

[Elastic body]
The elastic body that constitutes the heat-insulating elastic member of the present disclosure should have elasticity capable of being deformed following the expansion and contraction of the battery cell. For example, when the battery cell expands during charging, it is preferable that the thickness is reduced to about 1/3 to 1/4, especially about 1/2. The thickness of the elastic body may be appropriately determined in consideration of the interval between battery cells, the degree of expansion of the battery cells, and the like. For example, it may be 1 mm or more and 6 mm or less. When a crosslinked rubber composition is used for the elastic body, examples of the rubber component include ethylene-propylene-diene rubber (EPDM), silicone rubber, acrylonitrile-butadiene rubber (NBR), and the like. Among them, EPDM is preferable because it does not contain low-molecular-weight siloxane. Further, as the cross-linking agent for the rubber component, it is desirable to use an organic peroxide because it does not contain volatile components such as sulfur.

A plurality of elastic bodies are arranged at predetermined intervals on one side of the heat insulating sheet. The arrangement of the elastic bodies is not particularly limited, but from the viewpoint of well-balanced absorption of deformation due to expansion and contraction of the battery cells, it is desirable that the elastic bodies are arranged symmetrically on the surface of the heat insulating sheet laminated on the battery cells. The number of elastic bodies may be two or more. Alternatively, they can be arranged in strips so as to divide the Z direction. Alternatively, they may be arranged in islands on the YZ plane, such as by arranging them so as to divide the YZ plane into four.

The shape of the elastic body is not particularly limited. The surface on the battery cell side may be uneven as in the first and second embodiments, flat as in the third embodiment, or curved. Also, the elastic body may be solid or hollow. As in the first and second embodiments, when the ridges are provided, the number, shape, etc. of the ridges are not particularly limited. The cross section of the ridge in the thickness direction may be trapezoidal, rectangular, semicircular, or the like. When having a hollow portion as in the third embodiment, the size and shape of the hollow portion are not limited.

[Regulator]
The regulating body that constitutes the heat insulating elastic member of the present disclosure is made of a material different from that of the elastic body. The restrictor should be flame-retardant and have a lower thermal conductivity than the elastic body. The presence or absence of flame retardance can be determined, for example, by the following burner test. A sheet-shaped test piece having a thickness of 2 mm is prepared from the material of the regulator, and the test piece is exposed to an open flame of about 1000° C. for 10 seconds with a propane gas burner. As a result, if the test piece does not have a hole, it may be determined that the regulatory body "has flame retardancy." Furthermore, it is desirable to have compression resistance to withstand pressing force due to expansion when the temperature of the battery cell rises. The regulating body may be made of the same material as the constituent members of the heat insulating sheet.

The regulator can be made of flame-retardant cloth or flame-retardant paper. As the flame-retardant cloth, a flame-retardant and heat-insulating cloth that also has heat insulation properties is suitable. The flame-retardant heat insulating cloth includes a porous structure in which a plurality of fine particles are connected to form a skeleton, has pores inside, and has a hydrophobic site on at least the surface of the surface and the inside, and a heat insulating material having a binder. A layer supported on a cloth made of inorganic fibers can be mentioned. As will be described later in detail, the porous structure has a pore structure with a size of about 10 to 50 nm in which a plurality of fine particles are connected to form a skeleton. Therefore, the thermal conductivity of the porous structure is lower than that of air, and the heat insulating layer having the porous structure has high heat insulating properties. Examples of inorganic fiber cloth include woven cloth and nonwoven cloth formed from glass fiber, rock wool, ceramic fiber, and the like. Flame-retardant paper includes flame-retardant insulating paper manufactured as a composite material of pulp and magnesium silicate.

The shape of the regulator is not limited. The regulator may or may not be in contact with the battery cells during normal operation. The thickness of the regulating body may be appropriately determined depending on the hardness and behavior during compression, and may be the same as, greater than, or less than the thickness of the elastic body. If the regulating body is relatively hard, it should be thinner than the elastic body. For example, the thickness is preferably about 1/2 or less than the thickness of the elastic body. Conversely, if the restrictor is relatively soft, it may be as thick as or thicker than the elastic.

The number and layout of the regulating bodies are not limited, and may be arranged at least between the elastic bodies. The regulating bodies may be arranged so as to extend in one direction, may be arranged so as to intersect, for example, in a cross shape, or may be arranged in an island shape. In addition to being arranged so as to divide the elastic body, the regulating body may be arranged around one side of the heat insulating sheet, at the end of the battery pack on the cooling member side, or the like. By arranging the regulating bodies at these positions, it is possible to suppress the outflow of the melted material of the elastic body caused by the temperature rise of the battery cells. Moreover, when the regulator is arranged so as to include the central region on one side of the heat insulating sheet, the effect of suppressing the expansion of the battery cells is high, and it is effective in maintaining the gap between the battery cells and the heat insulating sheet.

[Insulation sheet]
The configuration of the heat insulating sheet constituting the heat insulating elastic member of the present disclosure is not limited as long as it is a sheet-shaped member having heat insulating properties. For example, it is desirable to configure the heat insulating sheet so as to have a heat insulating layer and a substrate supporting the heat insulating layer. Here, the heat insulating layer has a porous structure in which a plurality of fine particles are connected to form a skeleton, has pores inside, and has a hydrophobic site on at least the surface of the surface and the inside, and a binder. is desirable. A heat insulating sheet having such a structure can be produced by applying a composition for producing a heat insulating layer (composition for heat insulating layer) to a substrate and drying the composition.

The porous structure has hydrophobic sites on at least the surface of the surface and the interior. If the surface has a hydrophobic portion, it is possible to suppress penetration of moisture and the like, so that the pore structure is maintained and the heat insulating property is less likely to be impaired. For example, a function such as hydrophobicity can be imparted to the surface of the porous structure by surface treatment with a silane coupling agent or the like. Moreover, in the manufacturing process of the porous structure, a hydrophobic treatment such as imparting a hydrophobic group may be performed.

The type of porous structure is not particularly limited. Examples of primary particles include silica, alumina, zirconia, and titania. Among them, from the viewpoint of excellent chemical stability, a silica airgel in which the primary particles are silica, that is, a silica airgel in which a plurality of silica fine particles are linked to form a skeleton is desirable. Silica airgel is white and reflects infrared rays. Therefore, when silica airgel is used, a heat shielding effect can be imparted to the heat insulating layer.

The method for producing silica airgel is not particularly limited, and the drying process may be carried out under normal pressure or under supercritical conditions. For example, if the hydrophobizing treatment is performed before the drying step, the need for supercritical drying is eliminated, that is, the drying can be performed under normal pressure, which facilitates production at low cost. Due to the difference in drying method when producing airgel, the one dried at normal pressure may be called "xerogel", and the one dried under supercritical conditions may be called "aerogel", but both are used in this specification. It is called "aerogel" including.

As the binder, it is preferable to use a binder (aqueous binder) in which water (including pure water, tap water, etc.) is used as a solvent, from the viewpoint of facilitating the preparation of the heat insulating layer composition. As the binder, it is desirable to use an inorganic binder whose component is an inorganic material, from the viewpoint of reducing the decomposition and deterioration of the organic component at high temperatures and suppressing the occurrence of cracks and the like. Examples of inorganic materials include metal oxides such as silica, titania, zinc oxide, and zirconia, as well as water glass (sodium silicate), cement, gypsum, magnesium silicate, quicklime, and slaked lime. Among them, a binder containing silica is preferable because it is easily compatible with the porous structure and is inexpensive and readily available. In addition, it is possible to form a high-strength heat insulation layer by forming a binder while filling the gaps between porous structures while reacting with water, which is a solvent, and because it is inexpensive and easy to obtain, water The hard materials cement, gypsum, magnesium silicate are also suitable.

When the inorganic material is nanoparticles (particles on the order of nanometers), it is possible to improve the hardness and brittleness of the heat insulating layer due to the presence of the inorganic material. Colloidal silica using water as a dispersion medium, sodium silicate solution, or the like may be used as the binder having silica nanoparticles. As the binder containing nanoparticles of titania, an aqueous dispersion of titania may be used.

In addition to the porous structure and binder, the heat insulating layer may contain other ingredients such as cross-linking agents, thickeners, reinforcing fibers, flame retardants, and the like. A porous structure having hydrophobic sites on its surface or inside does not easily absorb water. Among them, silica airgel has a low specific gravity, so it easily floats on water. Therefore, it is difficult to disperse silica airgel in a binder liquid containing water as a solvent when preparing a composition for a heat insulating layer, and the dispersing step takes time. For example, when a thickener is blended, the viscosity of the binder liquid increases, the water-suspendability of the hydrophobic porous structure improves, and the porous structure becomes easier to disperse. Thereby, the time required for dispersing the porous structure can be shortened, and the productivity can be improved. In addition, since flexibility is imparted to the heat insulating layer, the occurrence of cracks is also suppressed. Examples of thickeners include polysaccharides such as carboxymethyl cellulose (CMC), polyethylene oxide (PEO), carboxyethyl cellulose, carboxypropyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, xanthan gum, agarose, and carrageenan, polyvinyl alcohol, and glucomannan. You can use it.

When the reinforcing fibers are blended, they are physically entangled around the porous structure, thereby improving the mechanical strength of the heat insulating layer and preventing the porous structure from coming off. Although the type of the reinforcing fiber is not particularly limited, ceramic fibers such as glass fiber and alumina fiber are suitable in consideration of heat resistance.

When a flame retardant is blended, flame retardancy can be imparted to the heat insulating layer. Halogen-based, phosphorus-based, metal hydroxide-based, and other known flame retardants may be used as the flame retardant. Considering the environmental load, it is desirable to use a phosphorus-based flame retardant. Phosphorus-based flame retardants include ammonium polyphosphate, red phosphorus, phosphate esters, and the like. Among them, a water-insoluble one is desirable, for example, ammonium polyphosphate, because the flame retardant is less likely to flow out even if it comes into contact with water during use.

Examples of materials for the base material include cloth, resin, and paper. Fibers constituting the cloth include glass fiber, rock wool, ceramic fiber, alumina fiber, silica fiber, carbon fiber, metal fiber, polyimide fiber, aramid fiber, polyphenylene sulfide (PPS) fiber and the like. Known ceramic fibers include refractory ceramic fibers (RCF), polycrystalline alumina fibers (PCW), and alkaline earth silicate (AES) fibers. Among them, AES fiber is more safe because it has biosolubility. Examples of resins include polyethylene terephthalate (PET), polyimide, polyamide, and PPS. Papers include pulp, pulp and magnesium silicate composites, and the like. The shape of the substrate is not particularly limited, and examples thereof include woven fabrics, non-woven fabrics, films, and sheets. For example, woven fabrics and non-woven fabrics made from inorganic fibers such as glass fibers and metal fibers such as glass cloth, and flame-retardant insulating papers made as composite materials of pulp and magnesium silicate have relatively low thermal conductivity. , the shape retention is high even in a high-temperature atmosphere. The substrate with high heat resistance may be manufactured from glass fiber, rock wool, ceramic fiber, polyimide, PPS, etc. Specifically, glass fiber nonwoven fabric, glass cloth, aluminum glass cloth, AES wool paper, polyimide fiber nonwoven fabric. etc.

In addition to the heat insulating layer, the heat insulating sheet may have a functional layer having functions such as flame retardancy, radiation heat dissipation, and electrical insulation. The functional layer may be laminated on one side or both sides of the heat insulating layer. The functional layer can be formed by binding functional materials such as mica, kaolinite, silica, talc, zirconia, and titanium oxide blended according to required functions with a binder. The heat insulating sheet may have a cover layer covering the sheet body composed of a heat insulating layer, a functional layer, and the like. By arranging the cover layer, the adhesiveness of the elastic body and the regulating body, the handleability, and the workability are improved. The cover layer comprises, for example, a high melting point material such as talc, kaolinite, montmorillonite, mica, silica, potassium titanate, titanium oxide, silicon nitride, alumina, aluminum nitride, silicon carbide, zirconia, and ammonium polyphosphate as a flame retardant. and a urethane resin as a binder. It may also be formed by including a high melting point material and colloidal silica. Further, as the cover layer, a glass cloth or a resin film made of polyimide or the like may be used.

[Exterior body]
An exterior body is not necessarily required, but by housing members such as a heat insulating sheet in a bag-like exterior body, each member can be integrated, and handling and workability are improved. A resin film made of PET, polypropylene (PP), or the like is suitable for the exterior body.

[battery pack]
The type of battery cell to which the heat insulating elastic member of the present disclosure is applied is not particularly limited. For example, a battery module formed by stacking a plurality of battery cells made of lithium-ion batteries and a heat insulating elastic member of the present disclosure is fastened from both sides in the stacking direction by fastening members and housed in a housing to form a battery pack. Can be configured.

1: battery pack, 2: battery cell, 10: housing, 30, 31, 32: heat insulating elastic member, 40, 43: heat insulating sheet, 41: sheet body, 42: cover layer, 44: exterior body, 50, 51 , 52, 53, 54, 55: elastic body, 60, 61: regulating body, 500, 520: flat plate portion, 501, 521: ridge portion, 540: hollow portion, 541: lightening portion.

Claims (14)

A heat insulating elastic member disposed between adjacent battery cells,
a heat insulating sheet;
a plurality of elastic bodies arranged at predetermined intervals on one side of the heat insulating sheet;
It is disposed between at least the elastic bodies on one side of the heat insulating sheet, is made of a material different from that of the elastic bodies, has flame retardancy, and has a thermal conductivity equal to or smaller than that of the elastic bodies. a regulatory body;
A heat insulating elastic member comprising: When the direction in which the battery cells are arranged is the X direction, and one of the two directions orthogonal to the X direction is the Y direction and the other is the Z direction,
the plurality of elastic bodies extend in the Y direction or the Z direction,
2. The heat insulating elastic member according to claim 1, wherein said restricting body is arranged between said adjacent elastic bodies. The Y direction is the longitudinal direction of the heat insulation sheet, the Z direction is the width direction of the heat insulation sheet,
the plurality of elastic bodies extending in the Y direction and arranged one by one at predetermined intervals in the Z direction;
3. The heat insulating elastic member according to claim 2, wherein the restricting body is arranged between the two elastic bodies and extends in the Y direction. The heat insulating elastic member according to any one of claims 1 to 3, wherein the regulating body is arranged so as to include a central region on one side of the heat insulating sheet. 5. The elastic body according to any one of claims 1 to 4, wherein each of the plurality of elastic bodies has a ridge portion that is in elastic contact with the adjacent battery cell, and the surface of the elastic body on the battery cell side exhibits unevenness. A thermal insulating elastic member as described. The heat insulating elastic member according to any one of claims 1 to 5, wherein each of the plurality of elastic bodies has a hollow portion. The regulation body is made of flame-retardant insulating cloth or flame-retardant paper,
The flame-retardant heat insulating cloth has a porous structure in which a plurality of fine particles are connected to form a skeleton, has pores inside, and has a hydrophobic site on at least the surface of the surface and the inside, and a heat insulating material having a binder. 7. The heat insulating elastic member according to any one of claims 1 to 6, wherein the layer is carried by an inorganic fiber cloth. Furthermore, it has a bag-shaped exterior body,
The heat insulating elastic member according to any one of claims 1 to 7, wherein the heat insulating sheet, the plurality of elastic bodies, and the regulating body are integrated by the exterior body. The heat insulating sheet has a heat insulating layer,
2. The heat insulating layer comprises a porous structure having a skeleton formed by connecting a plurality of fine particles, having pores inside, and having hydrophobic sites on at least the surface of the surface and the inside, and a binder. The heat insulating elastic member according to any one of claims 1 to 8. 10. The heat insulating elastic member according to claim 9, wherein the heat insulating sheet further has a substrate supporting the heat insulating layer. 11. The heat insulating elastic member according to claim 9, wherein the binder is an inorganic binder containing an inorganic material. 12. The heat insulating elastic member according to claim 11, wherein the inorganic material comprises at least one selected from silica, water glass, cement, gypsum, magnesium silicate, quicklime, and slaked lime. 13. The heat insulating elastic member according to any one of claims 9 to 12, wherein the heat insulating layer further contains one or more selected from a thickening agent and reinforcing fibers. 14. The heat insulating elastic member according to any one of claims 9 to 13, wherein the porous structure is silica airgel in which a plurality of silica fine particles are connected to form a skeleton.

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