battery pack

Abstract

To provide an assembled battery with low heat transfer to neighboring cells.SOLUTION: An assembled battery 10 comprises a plurality of cells 12 arranged with their wide faces facing each other, an insulating member 14 disposed between adjacent cells 12 of a plurality of cells 12, and a restraining member 16 that restrains the plurality of cells 12 and the insulating member 14. The insulating member 14 has a core material 14a with a bulkhead 14a1 extending along a direction in which the plurality of cells 12 is arranged and a plurality of cavities 14a2 surrounded by the bulkhead 14a1, and a film 14b covering an outer surface of the core material 14a. The cavity 14a2 of the core material 14a is under a low pressure, which is reduced from the atmosphere.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a battery pack. [Background technology]

[0002] Japanese Patent Application Laid-Open Publication No. 2020-2979 discloses an invention related to a heat insulating sheet. The heat insulating sheet disclosed therein contains A) resin and B) expandable graphite that exhibits expansion properties at a temperature of 110 to 160°C, and has a thickness of 10 μm to 3 mm. According to the publication, this heat insulating sheet is capable of suppressing thermal runaway while meeting the demand for high capacity and high density required for secondary batteries, particularly lithium-ion batteries. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-2979 Summary of the Invention [Problem to be solved by the invention]

[0004] It is desirable to provide a battery pack that is provided with a heat insulating member that is disposed between adjacent cells and that makes it difficult for heat to be transmitted to the adjacent cells. [Means for solving the problem]

[0005] The battery pack disclosed herein includes a plurality of cells arranged with their wide surfaces facing each other, a heat insulating member disposed between adjacent cells, and a restraining member that restrains the plurality of cells and the heat insulating member. The heat insulating member includes a partition wall extending in the direction in which the plurality of cells are arranged, a core material having a plurality of cavities surrounded by the partition wall, and a film that covers the outer surface of the core material. The cavities of the core material are under a low pressure state, reduced below atmospheric pressure.

[0006] In such a battery pack, heat is less likely to be transferred to adjacent cells. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a partial cross-sectional view schematically showing a battery pack 10. As shown in FIG. [Figure 2] FIG. 2 is a perspective view showing the structure of a heat insulating member 14A according to another embodiment. [Figure 3] FIG. 3 is a schematic diagram showing the manufacturing process of the heat insulating member 14 shown in FIG. [Figure 4] FIG. 4 is a schematic diagram showing the manufacturing process of a heat insulating member 14B according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] The disclosure herein is explained below. Unless otherwise specified, the disclosure herein is not intended to limit the invention described in the claims of this application. Each drawing is a schematic drawing and does not necessarily reflect the actual product. Furthermore, members and parts that perform the same function are appropriately designated by the same reference numerals, and redundant explanations will be omitted. In this specification, expressions such as "X to Y" that indicate a numerical range mean "X or more and Y or less" unless otherwise specified.

[0009] FIG. 1 is a partial cross-sectional view that schematically illustrates a battery pack 10. As shown in FIG. 1, the battery pack 10 includes a plurality of cells 12, a heat insulating member 14, and a restraining member 16. FIG. 1 illustrates a portion of the battery pack 10, showing cells 12(a) to 12(c) arranged with the heat insulating member 14 sandwiched between them. Here, the cells 12 are distinguished by the reference numerals 12(a), 12(b), and 12(c) in parentheses when necessary. Similarly, the heat insulating members 14 are distinguished by the reference numerals 14(a) and 14(b) in parentheses when necessary. FIG. 1 illustrates a state in which the plurality of cells 12 and the heat insulating members 14 are arranged in order and restrained by the restraining member 16.

[0010] <Cell 12> The cell 12 is a cell having a pair of opposing wide surfaces. Such a cell may be a rectangular energy storage device having a rectangular case having a substantially rectangular parallelepiped shape. It may also be a laminated cell covered with a laminate film. The multiple cells 12 are arranged with their wide surfaces 12a and 12b facing each other. Here, arrow L in FIG. 1 indicates the direction in which the multiple cells 12 are arranged with their wide surfaces 12a and 12b facing each other. In other words, arrow L may indicate the direction in which adjacent cells 12 face each other.

[0011] Here, "cell" refers to the smallest unit of an electricity storage device. "Electricity storage device" refers to a device that can charge and discharge. Electricity storage devices include batteries generally referred to as lithium ion batteries and lithium secondary batteries, as well as lithium polymer batteries and lithium ion capacitors. Secondary batteries generally refer to batteries that can be repeatedly charged and discharged through the movement of charge carriers between positive and negative electrodes. Electricity storage devices may use either a liquid electrolyte or a solid electrolyte. For example, the secondary battery may be a secondary battery that uses a so-called liquid electrolyte, or a so-called all-solid-state battery that uses a solid electrolyte. Furthermore, a "battery pack" is an electricity storage device incorporating multiple cells. Preferably, the cell 12 has a pair of wide opposing surfaces.

[0012] <Insulating material 14> The heat insulating members 14 are respectively disposed between adjacent cells 12(a), 12(b), and 12(c) among the plurality of cells. In the embodiment shown in FIG. 1, the heat insulating members 14 are respectively disposed between adjacent cells 12 among the plurality of cells 12 arranged with their wide surfaces facing each other. The embodiment is not limited to this, and the heat insulating members 14 may be disposed between at least some of the adjacent cells 12 among the plurality of cells 12 arranged with their wide surfaces facing each other. As shown in FIG. 1, the heat insulating members 14 include a core material 14a and a film 14b. Here, in FIG. 1, the heat insulating members 14(a) and 14(b) among the plurality of heat insulating members 14 are shown with the film 14b partially broken to expose the cross section of the core material 14a.

[0013] <Core material 14a> The core material 14a has partition walls 14a1 extending along the direction L in which the multiple cells 12 are arranged, and multiple cavities 14a2 surrounded by the partition walls 14a1. The cavities 14a2 are in a low-pressure state where the pressure in the cavities of the core material is reduced below atmospheric pressure. The core material 14a preferably has a required rigidity when compressed in the direction L in which the multiple cells 12 are arranged. From this perspective, the core material 14a may be made of a metal such as aluminum or stainless steel, a resin such as phenolic resin or aromatic polyamide, or an inorganic material such as SiC or carbon.

[0014] The partition walls 14a1 of the core material 14a may have, for example, a honeycomb structure. Here, the honeycomb structure refers to a structure in which regular hexagons and regular hexagonal pillars are arranged without gaps. The honeycomb structure is a suitable example of a lightweight structure having the required rigidity for the partition walls 14a1 of the core material 14a. However, the partition walls 14a1 of the core material 14a are not necessarily limited to a honeycomb structure as long as they have a structure that encloses cavities extending along the direction L in which the multiple cells 12 are arranged and have the required rigidity. The core material 14a may have partition walls 14a1 extending along the direction L in which the multiple cells 12 are arranged and multiple cavities 14a2 surrounded by the partition walls 14a1. For example, the core material 14a may have a structure in which cavities of different shapes, such as triangular or rectangular, are arranged without gaps.

[0015] <Film 14b> The film 14b preferably covers the outer surface of the core material 14a. The film 14b may cover the entire core material 14a. However, the film 14b is not limited thereto. The film 14b may cover at least both openings of the cavities 14a2 of the core material 14a, which extend along the direction L in which the cells 12 are arranged. This allows the cavities 14a2 of the core material 14a to be separated from the external space by the partition walls 14a1 of the core material 14a and the film 14b. The film 14b preferably serves as a member that separates the cavities 14a2 of the core material 14a from the outside while ensuring airtightness, and preferably has the required gas shielding properties (gas barrier properties). Furthermore, since the film 14b comes into contact with the cells, which generate heat during charging and discharging, it preferably has the required heat resistance. From this perspective, the film 14b may be made of a plastic film such as polyester, nylon, polycarbonate, or polypropylene. Among these, materials such as polycarbonate and polypropylene, which have high impact resistance and are inexpensive, can be suitably used.

[0016] <Cavity 14a2 of core material 14a> The hollow portion 14a2 of the core material 14a is preferably in a low-pressure state reduced below atmospheric pressure. For example, the core material 14a is prepared, and in a reduced-pressure atmosphere, the core material 14a is covered with a film and both ends of the hollow portion 14a2 are sealed. This allows the hollow portion 14a2 of the core material 14a to be in a low-pressure state reduced below atmospheric pressure. For example, the hollow portion 14a2 of the core material 14a is in a state of being in a space filled with gas at a pressure lower than atmospheric pressure, thereby suppressing heat conduction to a low level. From this perspective, the hollow portion 14a2 may be, for example, 10 -2 Pa~10 -4 It is preferable to ensure a degree of vacuum of about 100 Pa. Furthermore, it is preferable that the core material 14a and the film 14b have a rigidity that can withstand the degree of vacuum in the cavity 14a2.

[0017] In addition, the insulating member 14 is exemplified as a form in which a core material 14a is prepared, the core material 14a is covered with a film in a reduced pressure atmosphere, and both ends of the hollow portion 14a2 are sealed, but the structure of the insulating member 14 is not limited to this form.

[0018] <Insulating member 14A> FIG. 2 is a perspective view showing the structure of a heat insulating member 14A according to another embodiment. FIG. 3 is a schematic diagram showing a manufacturing process for the heat insulating member 14 shown in FIG. 2. As shown in FIG. 2, the heat insulating member 14 may include a ventilation material 14c disposed between the film 14b and the core material 14a, connecting the hollow portions 14a2 separated by the partition walls 14a1 of the core material 14a. The ventilation material 14c may be a fibrous sheet material, for example, a nonwoven fabric such as glass wool. The ventilation material 14c may be any material that forms a gap connecting the hollow portions 14a2 between the film 14b and the core material 14a, and may be, for example, a mesh material such as a wire mesh. The ventilation material 14c is layered on one side of the core material 14a so as to close one opening of the hollow portion 14a2, and a film 14b is further layered on the ventilation material 14c. Furthermore, in the heat insulating member 14A, a fibrous sheet member is disposed between the film 14b and the core material 14a as the ventilation material 14c, and this ventilation material 14c functions as a heat insulating material between the film 14b and the core material 14a. This can improve the function of preventing heat transfer between adjacent cells 12. From this perspective, it is preferable that the fibrous sheet member be made of fibers that can function as a heat insulating material, such as glass wool.

[0019] The film 14b covers the entire core material 14a. In this case, as shown in FIG. 3, ventilation materials 14c may be disposed on both sides of the hollow portion 14a2 of the core material 14a. One end of the film 14b may be provided with a suction port 14d. A vacuum pump (not shown) may be connected to the suction port 14d to remove air from inside the film 14b. At this time, air is removed from each hollow portion 14a2 of the core material 14a through the ventilation material 14c. This places the hollow portions 14a2 of the core material 14a at a pressure lower than the atmospheric pressure. After the air has been removed from each hollow portion 14a2 of the core material 14a and the hollow portions 14a2 of the core material 14a are at a pressure lower than the atmospheric pressure, the suction port 14d may be sealed.

[0020] <Insulating member 14B> FIG. 4 is a schematic diagram illustrating a manufacturing process for a heat insulating member 14B according to another embodiment. This heat insulating member 14B does not include ventilation material 14c, but instead includes recesses 14e formed at the upper edges of the partition walls 14a1 of the core material 14a as ventilation sections connecting the cavities 14a2 of the core material 14a. In this heat insulating member 14B, one end of the film 14b is provided with a suction port 14d. A vacuum pump (not shown) may be connected to the suction port 14d to remove air from the film 14b. At this time, air is removed from each of the cavities 14a2 of the core material 14a through the recesses 14e at the upper edges of the partition walls 14a1. This reduces the pressure of the cavities 14a2 in the core material 14a below atmospheric pressure. Thus, the partition walls 14a1 may be provided with ventilation sections 14e connecting the cavities 14a2 separated by the partition walls 14a1. In the embodiment shown in FIG. 4, the ventilation portion 14e is exemplified as a recess in the upper edge of the partition wall 14a1, but the ventilation portion 14e connecting the hollow portion 14a2 separated by the partition wall 14a1 may also be a hole formed in the partition wall 14a1.

[0021] As described above, the heat insulating member 14 includes partition walls 14a1 extending along the direction L (see FIG. 1) in which the cells 12 are arranged, a core material 14a having a plurality of cavities 14a2 surrounded by the partition walls 14a1, and a film 14b covering the outer surface of the core material 14a. The cavities 14a2 of the core material 14a are preferably in a low-pressure state that is reduced below atmospheric pressure. As described above, various structures can be adopted for the heat insulating member 14.

[0022] As shown in FIG. 1, the heat insulating member 14 has irregularities on the side surface 14f facing the wide surfaces 12a and 12b of the cells 12 to form gaps that serve as refrigerant flow paths. In the embodiment shown in FIG. 1, protrusions 14f1 may be provided on the side surface 14f of the heat insulating member 14. These protrusions 14f1 may be ridges. These protrusions 14f1 form gaps 14f2 that serve as refrigerant flow paths between the side surface 14f of the heat insulating member 14 and the wide surfaces 12a and 12b of the cells 12. The cells 12 can be cooled by the refrigerant (e.g., cooling air) flowing through the gaps 14f2.

[0023] The unevenness for forming the refrigerant flow path can be formed, for example, by attaching a plate to the side of the heat insulating member 14 and forming the unevenness for forming the flow path on the plate. The portion where the unevenness is formed may be made of plastic such as polyester or nylon. Alternatively, a plate may be attached to the side of the heat insulating member 14 and the portion where the unevenness is formed may be adhered to the plate with an adhesive. Alternatively, a plate or protruding member for forming the unevenness may be directly adhered to the side of the film 14b of the core material 14a of the heat insulating member 14. Alternatively, a plate with unevenness for forming the refrigerant flow path formed on it may be adhered to the side of the heat insulating member 14.

[0024] <Restraint member 16> The restraining member 16 is a member that restrains the plurality of cells 12 arranged with their wide surfaces facing each other and the insulating members 14 arranged between the cells 12 in an aligned state. The restraining member 16 may be configured to apply a required restraining pressure to the aligned plurality of cells 12 and the insulating members 14. The restraining member 16 may be configured, for example, with end plates 16a, 16b arranged at both ends of the aligned plurality of cells 12 and the insulating members 14, and a belt 16c stretched between the end plates 16a, 16b. In this embodiment, the belt 16c presses the end plates 16a, 16b arranged at both ends of the aligned plurality of cells 12 and the insulating members 14, and is connected to the end plates 16a, 16b in a state in which the aligned plurality of cells 12 and the insulating members 14 are subjected to the required restraining pressure. This allows the aligned plurality of cells 12 and the insulating members 14 to be maintained in a state in which the required restraining pressure is applied. The restraining member 16 may have a configuration that is used in battery packs.

[0025] As shown in FIG. 1 , the battery pack 10 includes a plurality of cells 12 arranged with their wide surfaces 12a, 12b facing each other, and a heat insulating member 14 disposed between adjacent cells 12. The heat insulating member 14 includes a core material 14a and a film 14b covering the outer surface of the core material 14a. The core material 14a has partition walls 14a1 extending along the direction L in which the cells 12 are arranged, and a plurality of cavities 14a2 surrounded by the partition walls 14a1. The cavities 14a2 in the core material 14a are in a low-pressure state, reduced below atmospheric pressure. Openings on both sides of the cavities 14a2 separated by the partition walls 14a1 of the core material 14a of the heat insulating member 14 face adjacent cells 12. In the battery pack 10, the heat insulating member 14 has the cavities 14a2 in a low-pressure state, and a vacuum region is interposed between adjacent cells 12. Therefore, in the battery pack 10, heat is less likely to be transferred to adjacent cells 12, and the cells 12 can be prevented from burning.

[0026] The insulating member 14 for a battery assembly disclosed herein is a member disposed between adjacent cells 12 arranged with their wide surfaces facing each other, as shown in FIG. 1 . The insulating member 14 includes a partition wall 14a1 extending along the direction L in which the adjacent cells 12 face each other, a core material 14a having multiple cavities 14a2 surrounded by the partition wall 14a1, and a film 14b covering the outer surface of the core material 14a. The cavities 14a2 of the core material 14a are under a low pressure, reduced from the atmospheric pressure. Therefore, the insulating member 14 reduces heat transfer to adjacent cells 12, thereby preventing the cells 12 from burning. As shown in FIG. 1 , the insulating member 14 for a battery assembly may have irregularities on the side surface 14f facing the wide surface 12a of the cells 12 to form voids that serve as flow paths for the refrigerant.

[0027] The invention disclosed herein has been described in various ways. Unless otherwise specified, the embodiments described herein do not limit the present invention. Furthermore, the embodiments of the invention disclosed herein can be modified in various ways, and each component and each process described herein can be omitted or combined as appropriate, unless a particular problem arises.

[0028] As described above, this specification includes the disclosures set forth in the following sections.

[0029] Section 1: A plurality of cells arranged with their wide surfaces facing each other; a heat insulating member disposed between adjacent cells among the plurality of cells; a restraining member that restrains the plurality of cells and the heat insulating member; Equipped with The heat insulating member includes partition walls extending along the direction in which the plurality of cells are arranged, a core material having a plurality of cavities surrounded by the partition walls, and a film covering an outer surface of the core material, and the cavities of the core material are in a low-pressure state reduced below atmospheric pressure. Battery pack.

[0030] Section 2: Item 2. The battery pack according to item 1, wherein the partition walls of the core material have a honeycomb structure.

[0031] Section 3: Item 3. The battery pack according to item 1 or 2, wherein a ventilation material is disposed between the film and the core material, connecting a cavity separated by a partition wall of the core material.

[0032] Section 4: 3. The battery pack according to item 1 or 2, wherein the partition has a vent that connects the cavities separated by the partition.

[0033] Section 5: 5. The battery pack according to any one of items 1 to 4, wherein the heat insulating member has irregularities on a side surface opposite to the wide surface of the cell to form gaps that serve as flow paths for a refrigerant.

[0034] Item 6: A heat insulating member disposed between adjacent cells among a plurality of cells arranged with their wide surfaces facing each other, a core material having partition walls extending in a direction in which the adjacent cells face each other, a plurality of cavities surrounded by the partition walls, and a film covering an outer surface of the core material, wherein the cavities of the core material are in a low-pressure state reduced below atmospheric pressure; Heat insulating material for battery packs. [Explanation of symbols]

[0035] 10 battery packs 12 cells 12a, 12b Wide surface of cell 12 14, 14A, 14B Heat insulating material (heat insulating material for battery pack) 14a Core material 14a1 Bulkhead 14a2 Cavity 14b film 14c Ventilated Material 14d suction port 14e Recess (ventilation area) 14f side 14f1 protrusion 14f2 void 16 Restraining member 16a, 16b End plates 16c belt L: The direction in which multiple cells 12 are arranged (the direction in which adjacent cells face each other)

Claims

1. A plurality of cells arranged with their wide surfaces facing each other; a heat insulating member disposed between adjacent cells among the plurality of cells; a restraining member that restrains the plurality of cells and the heat insulating member; Equipped with The heat insulating member is A core material and a film covering an outer surface of the core material, The core material is a plurality of cavities surrounded by partition walls extending in a direction in which the plurality of cells are arranged and the film; The hollow portion of the core material is in a low pressure state reduced below atmospheric pressure, A ventilation material is disposed between the film and the core material, connecting the cavity portion separated by the partition wall of the core material. Battery pack.

2. 2. The battery assembly according to claim 1, wherein the partition walls of the core material have a honeycomb structure.

3. The battery pack according to claim 1 , wherein the partition wall has a vent portion connecting the cavities separated by the partition wall.

4. 2. The battery pack according to claim 1, wherein the heat insulating member has irregularities on a side surface opposite to the wide surface of the cells to form gaps serving as flow paths for a coolant.

5. A heat insulating member disposed between adjacent cells among a plurality of cells arranged with their wide surfaces facing each other, A core material and a film covering an outer surface of the core material, The core material is a plurality of cavities surrounded by partition walls extending in a direction in which the plurality of cells are arranged and the film; The hollow portion of the core material is in a low pressure state reduced below atmospheric pressure, A ventilation material is disposed between the film and the core material, connecting the cavity portion separated by the partition wall of the core material. Heat insulating material for battery packs.

6. An insulating member for a battery pack as described in claim 5, wherein the partition walls of the core material have a honeycomb structure.

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