Battery pack and heat-insulating material

Abstract

Provided is a battery pack in which high-temperature gas discharged from an abnormal battery cell can be moved in a desired direction during thermal runaway. A battery pack according to the present invention comprises: a module having a plurality of battery cells provided with safety valves; a case for accommodating the module; and a heat-insulating material provided between the module and the case. The case has an exhaust duct formed so as to extend between the heat-insulating material and the case, and an exhaust port via which the exhaust duct communicates with the exterior of the case. The heat-insulating material includes a first heat-insulating sheet composed of a plurality of cover parts that cover each of the safety valves and a body section other than the cover parts. Each cover part is provided with a connection part and a cutting part formed along the contour of the cover part. The contour is formed by a first line connecting a first point and a second point, a second line connecting the second point and a third point, a third line connecting the third point and a fourth point, and a fourth line connecting the fourth point and the first point. The cutting parts are formed along the first line and the third line or along the second line and the fourth line.

Description

Battery pack and insulation

[0001] This invention relates to a battery pack and a thermal insulation material.

[0002] In battery packs where modules containing multiple battery cells are housed in a case, high-temperature gases and flames can be generated during thermal runaway. These gases and flames can spread to the surrounding area, potentially inducing further thermal runaway. To prevent a chain reaction of thermal runaway, safety valves have traditionally been installed in the modules to release the high-temperature gases generated during thermal runaway.

[0003] Furthermore, if the high-temperature gas discharged from the safety valve directly hits the case, the case temperature will rise, potentially causing thermal effects around the battery pack. To prevent this direct contact between the high-temperature gas and the case, insulating material has traditionally been placed between the module and the case.

[0004] As such a battery pack, Patent Document 1 discloses an energy storage device comprising: an energy storage stack including a plurality of energy storage cells, each having an exhaust valve on its upper surface; an upper case covering the energy storage stack from above; and a first heat-resistant sheet and a second heat-resistant sheet having heat resistance to exhaust gas discharged from the exhaust valves and being disposed between the upper case and the energy storage stack, wherein the first heat-resistant sheet is provided with a plurality of holes in positions that overlap each of the exhaust valves in the vertical direction, and the second heat-resistant sheet is disposed above the first heat-resistant sheet so as to cover the plurality of holes.

[0005] Furthermore, Patent Document 2 discloses a battery module composed of multiple stacked battery cells, each battery cell having an explosion-proof valve, an insulating cover covering the battery cell group, the insulating cover having an integral structure, the explosion-proof valves facing the insulating cover, and the insulating cover having a vulnerable region corresponding to each explosion-proof valve.

[0006] Japanese Patent Publication No. 2023-59480, Chinese Utility Model Publication No. 219457784, Specification

[0007] In Patent Document 1, it is necessary to discharge gas from abnormal cells in the event of thermal runaway, and for this purpose, the first heat-resistant sheet is provided with multiple holes. However, there is a possibility that the gas discharged from the abnormal cell may flow back through the holes and exhaust valve of adjacent cells and come into contact with adjacent cells. In this case, ignition (heat chain reaction) of adjacent cells may be triggered. Furthermore, although the gas discharged from the abnormal cell is to be discharged through a safety valve formed in the upper case, in the energy storage device described in Patent Document 1, the direction of movement of the gas discharged from the exhaust valve is not controlled, and there were cases where the gas moved in the opposite direction to the safety valve.

[0008] In Patent Document 2, the thermal insulation cover does not have a hole at the location corresponding to the explosion-proof valve of the battery cell, but a vulnerable area is provided. In the event of thermal runaway, the structure is designed so that the vulnerable area at the location corresponding to the explosion-proof valve of the abnormal battery cell ruptures due to the pressure of the gas discharged from the abnormal battery cell. In such a configuration, after the vulnerable area ruptures, the gas discharged from the abnormal battery cell directly hits the outer wall of the battery module, causing damage to the outer wall of the battery module.

[0009] This invention was made to solve the above problems, and the object of this invention is to provide a battery pack that can move high-temperature gas discharged from an abnormal battery cell in a desired direction during thermal runaway.

[0010] The present invention relates to a battery pack comprising: a module having a plurality of battery cells, each provided with a safety valve; a case housing the module; and a heat insulating material provided between the module and the case, wherein the case has an exhaust duct formed to extend in a first direction between the heat insulating material and the case, and an exhaust port formed on the first direction side of the case, communicating between the exhaust duct and the outside of the case, and the heat insulating material includes a first heat insulating sheet, and when the first heat insulating sheet is viewed in plan, the first heat insulating sheet consists of a plurality of covering portions that cover each of the plurality of safety valves, and a main body portion other than the covering portions, and one of the covering portions covers at least one of the safety valves The covering portion is positioned to overlap with a part of it, and the covering portion has a cut portion formed along the contour of the covering portion and a connecting portion formed along the contour of the covering portion other than the cut portion, and the contour of the covering portion is formed by a first line connecting the first and second points, a second line connecting the second and third points, a third line connecting the third and fourth points, and a fourth line connecting the fourth point and the first point, and the first line, second line, third line and fourth line are each line segments or curves, and the third line and first line are positioned in order along the first direction, and the cut portion is formed along the first line and third line, or along the second line and fourth line.

[0011] The battery pack of the present invention can prevent a chain reaction of thermal runaway caused by high-temperature gases from abnormal battery cells that occur during thermal runaway. The principle is explained below.

[0012] In the battery pack of this invention, a safety valve is provided in the module. Therefore, when the battery cell experiences thermal runaway and generates high-temperature gas, the gas is discharged from the safety valve. The gas discharged from the safety valve then reaches the insulating material.

[0013] The insulation material includes a first insulation sheet. When viewed from above, the first insulation sheet consists of multiple covering portions that cover each of the multiple safety valves, and a main body portion other than the covering portions. Therefore, the gas discharged from the safety valves will come into contact with the covering portions.

[0014] In the battery pack of the present invention, the covering portion has a cut portion formed along the contour of the covering portion and a connection portion formed along the contour of the covering portion other than the cut portion. When gas discharged from the safety valve hits the covering portion, the pressure causes the connection portion to bend, forming a gas flow path. By adjusting the formation positions of the cut portion and the connection portion, the structure of the gas flow path can be adjusted, making it possible to move the high-temperature gas discharged from a malfunctioning battery cell in a desired direction.

[0015] The gas discharged from the safety valve then travels through the exhaust duct along the first direction and is discharged to the outside through the exhaust port.

[0016] Furthermore, as the exhaust duct moves, the gas reaches other parts of the first insulation sheet's covering. However, these other parts of the first insulation sheet's covering are connected to the main body, and the pressure of the gas moving through the exhaust duct prevents them from separating from the main body. Therefore, even if the gas reaches other parts of the first insulation sheet's covering, it is blocked by the covering. Consequently, it is possible to prevent the gas from flowing back through the safety valves of other battery cells.

[0017] In the battery pack of the present invention, it is preferable that the figure formed by connecting the first, second, third, and fourth points in order with line segments is a rectangle. Such a structure makes it easier to control the direction of gas movement.

[0018] In the battery pack of the present invention, the cut portion may be formed along the first and third lines, the cut portion may be formed along the second line, and the connection portion may be formed along the fourth line, or the cut portion may be formed along the fourth line and the connection portion may be formed along the second line. When the cut portion and connection portion are formed in this manner, when the gas discharged from the safety valve hits the covering portion, the connection portion formed along the fourth line bends, and the main body portion and the covering portion separate at the cut portion formed along the first, second, and third lines. Alternatively, the connection portion formed along the second line bends, and the main body portion and the covering portion separate at the cut portion formed along the first, third, and fourth lines. In this case, the covering portion functions as a deflection plate and can control the direction of movement of the gas discharged from the safety valve in the direction from the fourth line toward the second line, or from the second line toward the fourth line.

[0019] In the battery pack of the present invention, the cut portion is formed along the second line, and the cut portions formed along the first line, the second line, and the third line may be continuous. Alternatively, in the battery pack of the present invention, the cut portion is formed along the fourth line, and the cut portions formed along the first line, the third line, and the fourth line may be continuous. When the cut portions are continuous in this way, the connection portion formed along the fourth line, or the connection portion formed along the second line, becomes more prone to bending.

[0020] In the battery pack of the present invention, the cut portion is formed along the first and third lines, and the connection portion may be formed along the second and fourth lines. When the cut portion and connection portion are formed in this manner, when the gas discharged from the safety valve hits the covering portion, the connection portion formed along the second and fourth lines acts as a fulcrum, causing the covering portion to bend so as to be convex in the direction of gas discharge. At the cut portion, the main body and the covering portion separate, creating a gas flow path. In this case, the covering portion functions as a deflection plate, and the direction of movement of the gas discharged from the safety valve is controlled to be either from the first line towards the third line, or from the third line towards the first line. Even when the covering portion is bent so as to be convex in the direction of gas discharge, the covering portion is still present between the safety valve and the case, so the gas discharged from the safety valve can be prevented from directly hitting the case.

[0021] In the battery pack of the present invention, the first heat insulating sheet has at least one first notch formed therein, at least a portion of which is inside the contour of the covering portion, and the first notch may be formed on a straight line intersecting the first line and the third line. When the cut portion, connecting portion and first notch portion are formed in this way, when the gas discharged from the safety valve hits the covering portion, the covering portion is divided along the first notch portion, the connecting portion formed along the second line and the fourth line bends, and the main body portion and the covering portion separate at the cut portion formed along the first line and the third line. In this case, the covering portion functions as a deflection plate and can control the direction of movement of the gas discharged from the safety valve in the direction from the second line to the fourth line and in the direction from the fourth line to the second line.

[0022] In the battery pack of the present invention, the first notch may be formed to be in contact with the cut portion. If the first notch is continuous in this way, the connecting portion formed along the second and fourth lines will be more prone to bending.

[0023] In the battery pack of the present invention, the cut portion is formed along the second and fourth lines, the cut portion is further formed along the first line, and the connection portion may be formed along the third line. When the cut portion and connection portion are formed in this manner, when the gas discharged from the safety valve hits the covering portion, the connection portion formed along the third line bends, and the main body and the covering portion separate at the cut portions formed along the first, second, and fourth lines. In this case, the covering portion functions as a deflection plate, and the direction of movement of the gas discharged from the safety valve can be controlled from the third line toward the first line.

[0024] In the battery pack of the present invention, the cut portions formed along the first, second, and fourth lines may be continuous. When the cut portions are continuous in this way, the connection portion formed along the third line becomes more prone to bending.

[0025] In the battery pack of the present invention, the cut portion is formed along the second and fourth lines, and the connection portion may be formed along the first and third lines. When the cut portion and connection portion are formed in this manner, when the gas discharged from the safety valve hits the covering portion, the connection portion formed along the first and third lines acts as a fulcrum, causing the covering portion to bend so as to be convex in the direction of gas discharge. At the cut portion, the main body and the covering portion separate, creating a gas flow path. In this case, the covering portion functions as a deflection plate, and the direction of movement of the gas discharged from the safety valve is controlled to be either from the second line towards the fourth line, or from the fourth line towards the second line. Even when the covering portion is bent so as to be convex in the direction of gas discharge, the covering portion is still present between the safety valve and the case, so the gas discharged from the safety valve can be prevented from directly hitting the case.

[0026] In the battery pack of the present invention, the total length of the cut portions may be longer than the total length of the connection portions. A total length of cut portions longer than the total length of connection portions means that there is less continuous space between the main body and the covering portion. In this case, the covering portion becomes more flexible due to the pressure of the gas discharged from the abnormal battery cell, and the direction of gas movement is quickly controlled.

[0027] In the battery pack of the present invention, the thickness of the first heat insulating sheet is preferably 0.05 to 2.0 mm. If the thickness of the first heat insulating sheet is less than 0.05 mm, the strength of the first heat insulating sheet will be low and it will be easily damaged. If the thickness of the first heat insulating sheet exceeds 2.0 mm, the first heat insulating sheet will be too thick, making it difficult to miniaturize the entire battery pack.

[0028] In the battery pack of the present invention, the plan view shape of the covering portion is preferably at least one selected from the group consisting of a square, a circle, an ellipse, and a racetrack shape. A covering portion of such a shape can be easily formed. Furthermore, by making the covering portion of such a shape, it becomes easier to control the direction of movement of gas discharged from a faulty battery cell.

[0029] In the battery pack of the present invention, the first heat insulating sheet is preferably at least one selected from the group consisting of mica sheets, heat-resistant resin sheets, inorganic fiber paper, and inorganic fiber cloth. These materials are suitable as the first heat insulating sheet.

[0030] In the battery pack of the present invention, the thermal insulation material further includes a second thermal insulation sheet and an adhesive layer for bonding the second thermal insulation sheet to the first thermal insulation sheet, and it is preferable that the thermal insulation material is arranged such that the second thermal insulation sheet is located on the module side and the first thermal insulation sheet is located on the case side. When such a second thermal insulation sheet is arranged, gas discharged from an abnormal battery cell passes through the second thermal insulation sheet before reaching the first thermal insulation sheet. As the gas passes through the second thermal insulation sheet, its temperature and pressure decrease. Therefore, even if the gas comes into contact with the case, the case is less likely to be heated or damaged by the gas.

[0031] In the battery pack of the present invention, the second heat insulating sheet has a second notch formed therein that extends from the main surface to which the first heat insulating sheet is bonded to the other main surface, and it is preferable that at least a part of the second notch is located inside the covering portion when the heat insulating material is viewed from the first heat insulating sheet side. When the second notch is formed in the second heat insulating sheet, high-temperature gas from the module side can easily reach the covering portion through the second notch.

[0032] In the battery pack of the present invention, when the heat insulating material is viewed from above from the first heat insulating sheet side, it is preferable that the second cut portion is formed in a linear shape. The linear second cut portion can be easily formed with a cutter or the like.

[0033] In the battery pack of the present invention, the first heat insulating sheet has at least one first notch formed therein, at least a portion of which is inside the contour of the covering portion, and it is preferable that when the heat insulating material is viewed in plan view from the first heat insulating sheet side, the first notch and the second notch overlap in the same shape. Such a first notch and a second notch can be formed simultaneously by punching out the first heat insulating sheet and the second heat insulating sheet while they are stacked on top of each other.

[0034] In the battery pack of the present invention, the second heat insulating sheet may be at least one selected from the group consisting of inorganic fiber mat, inorganic fiber paper, and inorganic fiber cloth. Among these, the inorganic fiber mat is preferred. These can be easily molded, and the inorganic fiber mat exhibits excellent performance as the second heat insulating sheet.

[0035] The present invention provides a sheet-like thermal insulation material comprising a main body and a covering portion formed on the inside of the main body, wherein the covering portion has a cut portion formed along the contour of the covering portion and a connecting portion formed along the contour of the covering portion other than the cut portion, the contour of the covering portion being formed by a first line connecting a first point and a second point, a second line connecting a second point and a third point, a third line connecting a third point and a fourth point, and a fourth line connecting a fourth point and a first point, the first line, the second line, the third line and the fourth line each being a line segment or a curve, the third line and the first line being positioned sequentially along the first direction, and the cut portion being formed along the first line and the third line, or along the second line and the fourth line.

[0036] The thermal insulation material of the present invention is used in the battery pack of the present invention described above. In this case, the covering portion of the thermal insulation material is positioned to cover the safety valves of the multiple battery cells arranged in the module. By positioning the thermal insulation material of the present invention in this manner, the effects of the battery pack of the present invention described above can be achieved.

[0037] According to the present invention, it is possible to provide a battery pack that can move high-temperature gas discharged from an abnormal battery cell in a desired direction during thermal runaway.

[0038] Figure 1A is a schematic perspective view showing an example of a battery pack according to the first embodiment of the present invention. Figure 1B is a cross-sectional view taken along line A-A in Figure 1A. Figure 1C is an exploded view of the battery pack shown in Figure 1A. Figure 2A is a schematic cross-sectional view showing an example of a safety valve and its vicinity in a battery pack according to the first embodiment of the present invention. Figure 2B is a plan view of the heat insulating material shown in Figure 2A, viewed from the bottom side of the housing portion of the case. Figure 3 is a schematic cross-sectional view showing an example of a state in which high-temperature gas is ejected when one battery cell experiences thermal runaway in a battery pack according to the first embodiment of the present invention. Figure 4A is a schematic cross-sectional view showing an example of a change in the covering portion when high-temperature gas strikes the covering portion in a battery pack according to the first embodiment of the present invention. Figure 4B is a perspective view of the covering portion shown in Figure 4A. Figure 5 is a schematic cross-sectional view showing an example of a state in which high-temperature gas moves through an exhaust duct in a battery pack according to the first embodiment of the present invention. Figure 6A is a schematic plan view showing an example of the covering portion in a battery pack according to the first embodiment of the present invention. Figure 6B is a schematic plan view showing an example of a coating portion in a battery pack according to the first embodiment of the present invention. Figure 6C is a schematic plan view showing an example of a coating portion in a battery pack according to the first embodiment of the present invention. Figure 7 is a schematic plan view showing an example of a coating portion in a battery pack according to the second embodiment of the present invention. Figure 8 is a schematic perspective view showing an example of a change in the coating portion when a high-temperature gas strikes the coating portion in a battery pack according to the second embodiment of the present invention. Figure 9 is a schematic plan view showing a modified example of the coating portion in a battery pack according to the second embodiment of the present invention. Figure 10 is a schematic plan view showing an example of a coating portion in a battery pack according to the third embodiment of the present invention. Figure 11 is a schematic perspective view showing an example of a change in the coating portion when a high-temperature gas strikes the coating portion in a battery pack according to the third embodiment of the present invention. Figure 12 is a schematic plan view showing an example of a coating portion in a battery pack according to the fourth embodiment of the present invention. Figure 13 is a schematic perspective view showing an example of a change in the coating portion when a high-temperature gas strikes the coating portion in a battery pack according to the fourth embodiment of the present invention. Figure 14 is a schematic plan view showing an example of a covering portion in a battery pack according to a fifth embodiment of the present invention.Figure 15 is a schematic perspective view showing an example of the changes in the coating when a high-temperature gas comes into contact with the coating in a battery pack according to the fifth embodiment of the present invention. Figure 16 is a schematic cross-sectional view showing an example of a battery pack according to the sixth embodiment of the present invention.

[0039] The battery pack of the present invention will be described in detail below. However, the present invention is not limited to the following configuration, and can be modified and applied as appropriate without changing the gist of the invention. Furthermore, a combination of two or more of the individual preferred configurations of the present invention described below also constitutes the present invention.

[0040] (First Embodiment) A battery pack according to the first embodiment of the present invention will be described with reference to the drawings. Figure 1A is a schematic perspective view showing an example of a battery pack according to the first embodiment of the present invention. Figure 1B is a cross-sectional view taken along line A-A in Figure 1A. Figure 1C is an exploded view of the battery pack shown in Figure 1A.

[0041] The battery pack 10 shown in Figures 1A, 1B, and 1C comprises a module 20 having a plurality of battery cells 21, each of which is provided with a safety valve 22, and a case 30 that houses the module 20.

[0042] As shown in Figures 1A and 1B, the case 30 comprises a housing section 31 consisting of a bottom section 31b and side walls 31s, and a lid section 32 that covers the housing section 31, with the module 20 housed in the housing section 31. In addition, in the battery pack 10, an insulating material 40 is provided between the module 20 and the case 30.

[0043] As shown in Figure 1B, the case 30 has an exhaust duct 33 formed between the thermal insulation material 40 and the case 30 so as to extend in a first direction D, and an exhaust port 34 formed in the side wall 31s of the case 30 in the first direction D, which communicates the exhaust duct 33 with the outside of the case 30.

[0044] The battery cell 21 stores power and is preferably a rechargeable secondary battery, for example. Examples of secondary batteries include lithium-ion batteries, nickel-metal hydride batteries, and sodium-ion batteries. The battery cell 21 shown in Figures 1B and 1C is rectangular in shape. However, in the battery pack of the present invention, the battery cell may have a three-dimensional shape other than a rectangular parallelepiped (for example, a cube or an irregular shape).

[0045] As shown in Figures 1B and 1C, in the module 20, multiple battery cells 21 are arranged in a row and fixed by a connecting module member 20a. Also, as shown in Figure 1C, each battery cell 21 has terminals 23, and adjacent battery cells 21 are electrically connected by busbars 20b located on the connecting module member 20a, with each terminal 23 connected.

[0046] The busbar 20b is a flat, conductive metal component. Examples of materials for the busbar 20b include copper, copper alloy, stainless steel (SUS), and aluminum. The busbar 20b may be fixed to the terminal 23 by any fixing means (e.g., screwing, welding, etc.).

[0047] The materials that make up the case 30 include steel, aluminum, and the like. Stainless steel (SUS) is preferred as the steel material.

[0048] Figure 2A is a schematic cross-sectional view showing an example of a safety valve and its vicinity in a battery pack according to the first embodiment of the present invention. Figure 2B is a plan view of the heat insulating material shown in Figure 2A, seen from the bottom side of the housing portion of the case.

[0049] As shown in Figure 2A, the thermal insulation material 40 consists of a first thermal insulation sheet 41. Also, as shown in Figure 2B, when the first thermal insulation sheet 41 is viewed from above, it consists of multiple covering portions 41a that cover each of the multiple safety valves 22, and a main body portion 41b other than the covering portions 41a. Furthermore, one covering portion 41a is positioned to overlap with one of the safety valves 22.

[0050] The covering portion 41a has a cutting portion 50 formed along the contour C of the covering portion 41a and a connecting portion 41c formed along the contour C of the covering portion 41a other than the cutting portion 50. The contour C of the covering portion 41a is rectangular, and the first point P １ and the second point P ２ connecting the first line S １ and the second point P ２ and the third point P ３ connecting the second line S ２ and the third point P ３ and the fourth point P ４ connecting the third line S ３ and the fourth point P ４ and the first point P １ connecting the fourth line S ４ are formed by. And along the first direction D, the third line S ３ and the first line S １ are located in order. Note that the cutting portion 50 can be easily formed by a cutter or the like.

[0051] In the first heat insulating sheet 41, the cutting portion 50 is formed along the first line S １ , the second line S ２ and the fourth line S ４ , and the connecting portion 41c is formed along the third line S ３ . Also, the cutting portions 50 formed along the first line S １ , the second line S ２ and the fourth line S ４ are continuous.

[0052] In the battery pack 10, it is possible to prevent the chain reaction of thermal runaway due to the high-temperature gas from the abnormal battery cell generated during thermal runaway, and it is also possible to move the high-temperature gas in a desired direction. The principle will be explained below.

[0053] Figure 3 is a schematic cross-sectional view showing an example of a state in which high-temperature gas is ejected when one battery cell experiences thermal runaway in a battery pack according to the first embodiment of the present invention. As shown in Figure 3, when one battery cell 21a experiences thermal runaway and high-temperature gas is generated from the battery cell 21a, gas G (in Figure 3, gas is indicated by the symbol "G", and the direction of gas flow is indicated by an arrow) is discharged from the safety valve 22a. The gas discharged from the safety valve 22a then reaches the heat insulating material 40 (first heat insulating sheet 41).

[0054] The first heat insulating sheet 41 consists of multiple covering portions 41a that cover each of the multiple safety valves 22, and a main body portion 41b other than the covering portions 41a. Therefore, the gas G released from the safety valve will come into contact with the covering portions 41a.

[0055] Figure 4A is a schematic cross-sectional view showing an example of the changes in the coating when a high-temperature gas strikes the coating portion in a battery pack according to the first embodiment of the present invention. Figure 4B is a perspective view of the coating portion shown in Figure 4A.

[0056] In the battery pack 10, the first wire S is present in the covering portion 41a. １ , second line S ２ Initially, line 4 S ４ A cut portion 50 formed along the third line S ３ There is a connecting portion 41c formed along the line. As shown in Figures 4A and 4B, when the gas G discharged from the safety valve 22 hits the covering portion 41a, the pressure causes the third line S ３ The connecting portion 41c formed along the first line S is bent, １ , second line S ２ Initially, line 4 S ４ In the cut section 50 formed along the first line S, the main body 41b and the covering 41a are separated. This creates a flow path for the gas G. In particular, in the battery pack 10, the first line S １ , second line S ２ Initially, line 4 S ４ Since the cut portion 50 formed along the third line S is continuous, ３ The connecting portion 41c, formed along the curve, becomes more flexible.

[0057] The deformed covering portion 41a functions as a deflection plate, and the direction of movement of the gas G discharged from the safety valve 22 is the third line S ３ From the first line S １ It is controlled in the direction toward (i.e., the first direction D).

[0058] Figure 5 is a schematic cross-sectional view showing an example of the state in which high-temperature gas moves through the exhaust duct in a battery pack according to the first embodiment of the present invention. As shown in Figure 5, the gas G discharged from the safety valve 22 moves through the exhaust duct 33 along the first direction D and is discharged to the outside from the exhaust port (not shown).

[0059] Furthermore, when the exhaust duct 33 is moved, the gas G released between the first insulation sheet 41 and the case 30 also reaches other covering portions 41a of the first insulation sheet 41. However, the other covering portions 41a of the first insulation sheet 41 are connected to the main body portion 41b by a connecting portion 41c, and the connecting portion 41c does not detach from the main body due to the pressure of the gas G released between the first insulation sheet 41 and the case 30. Therefore, even if the gas reaches other covering portions 41a of the first insulation sheet 41, the gas G is blocked by the covering portion 41a. This prevents the gas G from flowing back through the safety valve 22 of other battery cells 21.

[0060] The following describes preferred embodiments of the thermal insulation material for the battery pack according to the first embodiment of the present invention. Note that the thermal insulation material used in the battery pack according to the first embodiment of the present invention is also an embodiment of the present invention.

[0061] In the battery pack 10, the first heat insulating sheet 41 is preferably at least one selected from the group consisting of mica sheets, heat-resistant resin sheets, inorganic fiber paper, and inorganic fiber cloth. These materials are suitable as the first heat insulating sheet.

[0062] Examples of resins that make up heat-resistant resin sheets include polybutylene terephthalate, polyamide, polypropylene, silicone, and urethane. These resins may also contain inorganic fibers such as glass fiber or silica fiber, or inorganic particles such as alumina and calcium carbonate, as fillers.

[0063] Inorganic fiber paper is preferably given a thermal conductivity of less than 1 (W / m·K). The thermal conductivity can be measured in accordance with the "Test Method for Thermal Conductivity of Refractories" described in JIS R 2251.

[0064] The inorganic fibers that make up inorganic fiber paper include alumina fiber, carbon fiber, basalt fiber, soluble fiber, refractory ceramic fiber, glass fiber, glass wool, slag wool, and SiO ２ At least one of the following can be used: fibers containing [unspecified material], silica fibers, mullite fibers, alumina silicate fibers, ceramic fibers, rock wool, alkali earth silicate fibers, zirconia fibers, silicon carbide fibers, magnesium silicate fibers, potassium titanate fibers, aerogel composites, and mineral fibers. These inorganic fibers have excellent heat resistance.

[0065] The inorganic fibers constituting the inorganic fiber paper preferably have an average fiber diameter of 1 to 20 μm, and more preferably 3 to 15 μm. Within this range, inorganic fiber paper can be manufactured without impairing moldability or processability.

[0066] The inorganic fibers constituting the inorganic fiber paper preferably have an average fiber length of 0.1 to 100 mm. Within this range, problems such as impaired moldability and processability due to an average fiber length that is too long, and a decrease in mechanical strength due to an average fiber length that is too short, are less likely to occur.

[0067] Furthermore, in addition to the inorganic fibers mentioned above (hereinafter also referred to as the first inorganic fibers), inorganic fibers with an average fiber diameter smaller than that of the first inorganic fibers (hereinafter referred to as the second inorganic fibers) may also be used. By using two inorganic fibers with different fiber diameters, the flexibility of the inorganic fiber paper can be improved, and the retention of other components, such as inorganic particles and organic particles, which will be described later, can be improved.

[0068] The average fiber diameter of the second inorganic fiber is preferably 1 nm or more and less than 1 μm, and more preferably 10 nm or more and 0.1 μm or less. Within this range, the second inorganic fiber can maintain flexibility while retaining mechanical strength.

[0069] Furthermore, the average fiber length of the second inorganic fiber is preferably less than 1 μm in order to avoid impairing moldability.

[0070] Furthermore, the inorganic fiber paper may also contain other components such as organic fibers, inorganic particles, organic particles, and resin binders.

[0071] The organic fibers contained in the inorganic fiber paper may be at least one selected from polyethylene terephthalate fibers, polybutylene terephthalate fibers, polytrimethylene terephthalate fibers, polyacetal fibers, polytetrafluoroethylene fibers, polyether ether ketone fibers, polyphenylene sulfide fibers, polyamide fibers, poly-p-phenylphthalamide fibers, polyvinyl alcohol fibers, polyethylene fibers, nylon fibers, polyurethane fibers, polypropylene fibers, and ethylene-vinyl alcohol copolymer fibers.

[0072] The average fiber length of the organic fibers is not particularly limited, but is preferably 0.5 to 10 mm. Within this range, sufficient compressive strength can be obtained without impairing the moldability or shape retention of the inorganic fiber paper.

[0073] The inorganic particles contained in the inorganic fiber paper can be materials with an average secondary particle diameter in the range of 0.01 to 200 μm. If the average secondary particle diameter is within this range, the material is readily available and the desired heat insulation effect can be obtained. Furthermore, it is preferable that the average secondary particle diameter of the inorganic particles is 0.05 to 100 μm.

[0074] Inorganic particles contained in inorganic fiber paper include oxide particles, nanoparticles, inorganic hydrate particles, particles made of thermally expandable inorganic materials, and water-containing porous materials.

[0075] The inorganic particles contained in the inorganic fiber paper may consist of two or more types of inorganic particles with different average secondary particle sizes. Since different sizes of inorganic particles result in different heat transfer suppression effects, heat transfer from the battery cell can be cooled in multiple stages, and a heat absorption effect can be achieved over a wide temperature range.

[0076] When the inorganic particles contained in inorganic fiber paper are oxide particles, at least one particle selected from silica, titania, zirconia, zircon, barium titanate, zinc oxide, and alumina can be used as the oxide particle. Because these oxide particles have a high refractive index, they can prevent radiant heat generated by thermal runaway of battery cells from propagating to adjacent cells or outside the battery pack.

[0077] When the inorganic particles contained in inorganic fiber paper are oxide particles, the average primary particle diameter of the oxide particles is preferably 1 to 50 μm in order to maximize the radiant heat shielding effect. The average primary particle diameter is determined by measuring the particle diameter of 10 arbitrary particles with a standard scale using a microscope and averaging the particle diameters of the measured 10 particles.

[0078] The nanoparticles that make up the inorganic particles contained in inorganic fiber paper have an average primary particle diameter of less than 1 μm. Nanoparticles have extremely low conductive heat transfer and excellent thermal insulation properties.

[0079] For example, if oxide particles are used as nanoparticles, even if the internal density increases due to compression of the inorganic fiber paper caused by expansion resulting from thermal runaway of the battery cell, the electrostatic repulsive force of the nanoparticles easily creates fine voids between the particles, and the particles are filled in a cushioning manner, thereby suppressing the increase in conductive heat transfer.

[0080] Silica nanoparticles are preferred as nanoparticles. Silica nanoparticles have high thermal insulation properties and are characterized by small contact points between particles, resulting in low heat conduction between particles. Therefore, using silica nanoparticles can further improve the thermal insulation properties of inorganic fiber paper. Wet silica, dry silica, aerogel, etc., can be used as silica nanoparticles.

[0081] The average primary particle size of the nanoparticles is preferably 1 to 100 nm. Within this range, convective and conductive heat transfer in the inorganic fiber paper can be suppressed in the temperature range during thermal runaway of the battery cell. Furthermore, even when compressive stress is applied to the inorganic fiber paper due to the expansion of the battery pack, the voids between the nanoparticles and the contact points between many particles suppress heat transfer in the inorganic fiber paper, maintaining the thermal insulation properties of the inorganic fiber paper. The average primary particle size of the nanoparticles is more preferably 2 nm or more, and even more preferably 3 nm or more. On the other hand, the average primary particle size of the nanoparticles is preferably 50 nm or less, and even more preferably 10 nm or less.

[0082] Examples of inorganic hydrate particles that make up the inorganic particles contained in inorganic fiber paper include particles of aluminum hydroxide, magnesium hydroxide, calcium hydroxide, zinc hydroxide, iron hydroxide, manganese hydroxide, zirconium hydroxide, and gallium hydroxide. If the inorganic hydrate particles are as described above, they will start thermal decomposition in the thermal runaway environment of the battery cell and release crystalline water, thereby releasing heat from the heat source and suppressing a rapid temperature rise inside the battery pack.

[0083] Examples of particles made from thermally expandable inorganic materials that constitute the inorganic particles contained in inorganic fiber paper include vermiculite, bentonite, and perlite.

[0084] Examples of particles made of water-containing porous materials that constitute the inorganic particles contained in inorganic fiber paper include zeolite, montmorillonite, acid clay, diatomaceous earth, wet silica, dry silica, aerogel, mica, and vermiculite.

[0085] When an inorganic fiber paper contains a resin binder, its mechanical strength is improved. This allows the inorganic fiber paper to maintain its shape even when compressed due to the expansion of battery cells during thermal runaway, thereby suppressing the deterioration of its thermal insulation performance. Examples of resin binders that can be included in inorganic fiber paper include styrene-butadiene resin, acrylic resin, silicone-acrylic resin, and styrene resin.

[0086] Inorganic fiber cloth is made by weaving inorganic fibers into a cross shape. Such inorganic fiber cloth has high strength and high heat resistance.

[0087] Examples of inorganic fibers that make up inorganic fiber cloth include silica fibers, alumina fibers, aluminosilicate fibers, ceramic fibers such as zirconia fibers, glass fibers, and basalt fibers. These inorganic fibers may be used individually or in mixtures of two or more types. For example, when producing inorganic fiber cloth, the warp and weft threads may be made of different types of inorganic fibers and then knitted together to form the inorganic fiber cloth.

[0088] When the first heat insulating sheet 41 is a mica sheet or a heat-resistant resin sheet, the thickness of the first heat insulating sheet 41 is preferably 0.05 to 2.0 mm, more preferably 0.1 to 1.0 mm, and even more preferably 0.1 to 0.5 mm. If the thickness of the first heat insulating sheet, which is made of a mica sheet or a heat-resistant resin sheet, is less than 0.05 mm, the strength of the first heat insulating sheet will be low and it will be easily damaged. If the thickness of the first heat insulating sheet, which is made of a mica sheet or a heat-resistant resin sheet, exceeds 2.0 mm, the first heat insulating sheet will be too thick, making it difficult to miniaturize the entire battery pack.

[0089] Furthermore, when the first heat insulating sheet 41 is inorganic fiber paper, the thickness of the first heat insulating sheet 41 is preferably 0.5 to 5.0 mm, and more preferably 0.8 mm to 3.0 mm. In this case, the first heat insulating sheet 41 made of inorganic fiber paper can obtain sufficient mechanical strength.

[0090] Furthermore, when the first heat insulating sheet 41 is an inorganic fiber cloth, the thickness of the first heat insulating sheet 41 is preferably 0.1 to 5.0 mm, and more preferably 0.3 mm to 1.4 mm. In this case, both mechanical strength and flexibility can be achieved for the first heat insulating sheet 41 made of inorganic fiber cloth. Therefore, the first heat insulating sheet 41 made of inorganic fiber cloth can be bent to fit a predetermined shape and used.

[0091] The area of ​​the planar shape of the covering portion 41a is 1.0 to 18 cm². ２ Preferably, it is 3 to 12 cm ２ It is more preferable that the area of ​​the planar shape of the covered portion is 1.0 cm². ２ If it is less than 18 cm², the gas will have difficulty passing through the area where the covering portion 41a was located. ２ Beyond a certain point, the covered area tends to become larger than the range the gas can reach. As a result, the covered area becomes less prone to deformation, making it difficult for a gas flow path to form.

[0092] In the battery pack 10, when the first heat insulating sheet 41 is viewed through from above, it is sufficient that one covering portion 41a overlaps with at least a part of one safety valve 22, but it is preferable that one covering portion 41a is positioned so that it fits inside the contour of one safety valve 22. When the covering portion 41a is positioned in this way, the gas released from the safety valve 22 can easily reach the covering portion 41a.

[0093] In the battery pack 10, the first line S １ , second line S ２ Initially, line 4 S ４ Although the cut portion 50 formed along the first line S was continuous, in the battery pack according to the first embodiment of the present invention, the cut portion does not have to be continuous. １ , second line S ２ Initially, line 4 S ４ A connection point exists in this section. With this configuration, if gas comes into contact with the covering, the first line S １ , second line S ２ Initially, line 4 S ４ The connection formed along the third line S breaks,３ The connection formed along the first line S will bend. For the connection to bend in this way, the first line S １ , second line S ２ Initially, line 4 S ４ The cut section 50 formed along the curve requires higher pressure compared to the case where it is continuous. By adjusting the position of the cut section depending on the expected gas pressure during thermal runaway and the material and size of the first insulation sheet, the ease with which the covering portion deforms can be adjusted.

[0094] In the battery pack according to the first embodiment of the present invention, the total length of the cut portions may be longer than the total length of the connection portions. A total length of cut portions longer than the total length of connection portions means that there is less continuous space between the main body and the covering portion. In this case, the covering portion becomes more flexible due to the pressure of the gas discharged from the abnormal battery cell, and the direction of gas movement is quickly controlled.

[0095] In the battery pack 10, the plan view shape of the covering portion 41a was rectangular, but in the battery pack according to the first embodiment of the present invention, the plan view shape of the covering portion does not have to be rectangular. The shapes of the covering portion that can be adopted in the battery pack according to the first embodiment of the present invention are described below.

[0096] In the battery pack 10, point P １ , second point P ２ , third point P ３ and point P ４ In the first embodiment of the present invention, the figure formed by connecting the first, second, third, and fourth points in order with line segments is a rectangle. However, in the battery pack according to the first embodiment of the present invention, the figure formed by connecting the first, second, third, and fourth points in order with line segments is not necessarily a rectangle. However, from the viewpoint of making it easier to control the direction of gas movement, it is preferable that the figure formed by connecting the first, second, third, and fourth points in order with line segments is a rectangle.

[0097] In the battery pack 10, the first line S forms the contour C of the covering portion 41a. １ , second line S ２ , 3rd line S ３ Initially, line 4 S ４Although the first line was a line segment, in the battery pack according to the first embodiment of the present invention, the first, second, third, and fourth lines may be curves, and line segments and curves may be mixed.

[0098] The following diagrams illustrate the plan view shape of the covering portion when the figure formed by connecting the first, second, third, and fourth points in order with line segments is a rectangle and the first, second, third, and fourth lines are curves, and when the figure formed by connecting the first, second, third, and fourth points in order with line segments is a rectangle and the first, second, third, and fourth lines are a mixture of line segments and curves. Figures 6A to 6C are schematic plan views showing an example of a covering portion in a battery pack according to the first embodiment of the present invention.

[0099] The covering portion 41a-A shown in Figure 6A is circular. In other words, in the covering portion 41a-A, the first point P １ , second point P ２ , third point P ３ and point P ４ The figure formed by connecting these points in order with line segments is a rectangle (square), and the first line S １ , second line S ２ , 3rd line S ３ Initially, line 4 S ４ It is a curve.

[0100] The covering portion 41a-B shown in Figure 6B is elliptical. That is, in the covering portion 41a-B, the first point P １ , second point P ２ , third point P ３ and point P ４ The figure formed by connecting these points in order with line segments is a rectangle, and the first line S １ , second line S ２ , 3rd line S ３ Initially, line 4 S ４ It is a curve.

[0101] The covering portion 41a-C shown in Figure 6C is racetrack shaped. In other words, in the covering portion 41a-C, the first point P １ , second point P ２ , third point P ３ and point P ４ The figure formed by connecting these points in order with line segments is a rectangle, and the first line S１ and the third line S ３ This is a line segment, and the second line S ２ Initially, line 4 S ４ It is a curve.

[0102] In the battery pack according to the first embodiment of the present invention, the shape of the covering portion may be trapezoidal or parallelogram.

[0103] Next, the uses and arrangement methods of the battery pack according to the first embodiment of the present invention will be described.

[0104] The battery pack according to the first embodiment of the present invention is not particularly limited in its use, but may be used, for example, as a power source for an electric vehicle.

[0105] Furthermore, in the battery pack according to the first embodiment of the present invention, it is preferable that the safety valve provided on the battery cell is positioned either vertically upward or vertically downward. When the battery pack is positioned in this way, high-temperature gas from an abnormal battery cell is naturally and quickly dispersed, making it less likely for a chain reaction of thermal runaway to occur. In other words, from the viewpoint of fail-safe, this is a preferred arrangement for the battery pack. However, in the battery pack according to the first embodiment of the present invention, the safety valve provided on the battery cell may be positioned in a direction other than vertically upward and vertically downward (i.e., laterally).

[0106] In the battery pack according to the first embodiment of the present invention, the safety valve may be positioned on the bottom side or on the lid side. As described above, when arranging the battery pack according to the first embodiment of the present invention, from the viewpoint of fail-safe, the battery pack may be arranged so that the safety valve is positioned on the vertically upper side or vertically lower side. Since the battery pack is often arranged so that the bottom of the case or the lid is on the lower side, arranging the safety valve to be positioned on the bottom side or the lid side of the case makes it easier to position the safety valve on the vertically upper side or vertically lower side.

[0107] (Second Embodiment) Next, a battery pack according to the second embodiment of the present invention will be described. In the battery pack according to the second embodiment of the present invention, the cutting portion is formed along the first line, the second line, and the third line, and the connection portion is formed along the fourth line, which is different from the battery pack according to the first embodiment of the present invention. The covering portion according to the second embodiment of the present invention will be described with reference to the drawings.

[0108] FIG. 7 is a plan view schematically showing an example of a covering portion in a battery pack according to the second embodiment of the present invention. The contour C of the covering portion 141a shown in FIG. 7 is rectangular, and the first line S connecting the first point P １ and the second point P ２ , the second line S connecting the second point P １ and the third point P ２ , the third line S connecting the third point P ３ and the fourth point P ２ , and the fourth line S connecting the fourth point P ３ and the first point P ４ are formed by ３ and the fourth line S connecting the fourth point P ４ and the first point P １ . And along the first direction D, the third line S ４ and the first line S ３ are located in order. １ are located in order.

[0109] In the covering portion 141a, the cutting portion 150 is formed along the first line S １ , the second line S ２ , and the third line S ３ , and the connection portion 141c is formed along the fourth line S ４ . Note that the connection portion 141c connects the covering portion 141a and the main body portion 141b. Also, the cutting portion 150 formed along the first line S １ , the second line S ２ , and the third line S ３ is continuous.

[0110] Next, the case where high-temperature gas from an abnormal battery cell generated during thermal runaway hits the covering portion 141a will be described. FIG. 8 is a perspective view schematically showing an example of the change in the covering portion when high-temperature gas hits the covering portion in the battery pack according to the second embodiment of the present invention.

[0111] As shown in Figure 8, when gas G hits the coating portion 141a, the pressure causes the fourth line S ４ The connecting portion 141c formed along the first line S is bent, １ , second line S ２ and the third line S ３ In the cut portion 150 formed along the first line S, the main body portion 141b and the covering portion 141a are separated. This creates a flow path for gas G. In particular, the first line S １ , second line S ２ and the third line S ３ Since the cut portion 150 formed along the fourth line S is continuous, ４ The connecting portion 141c formed along the curve becomes more flexible.

[0112] The deformed covering portion 141a functions as a deflection plate, and the direction of movement of the gas G discharged from the safety valve is the fourth line S. ４ From the second line S ２ It is controlled in the direction toward that direction.

[0113] In the covered portion 141a, the first line S １ , second line S ２ and the third line S ３ Although the cut portion 150 formed along the curve was continuous in the first embodiment of the present invention, the cut portion does not have to be continuous in the second embodiment of the present invention.

[0114] In the battery pack according to the second embodiment of the present invention, the total length of the cut portions may be longer than the total length of the connection portions. A total length of cut portions longer than the total length of connection portions means that there is less continuous space between the main body and the covering portion. In this case, the covering portion becomes more flexible due to the pressure of the gas discharged from the abnormal battery cell, and the direction of gas movement is quickly controlled.

[0115] In the battery pack according to the second embodiment of the present invention, the shape of the covering portion that can be used is the same as the shape of the covering portion that can be used in the battery pack according to the first embodiment of the present invention.

[0116] Next, a modified example of the battery pack according to the second embodiment of the present invention will be described. Figure 9 is a schematic plan view showing a modified example of the covering portion in the battery pack according to the second embodiment of the present invention. In the covering portion 141a-1 shown in Figure 9, the cut portion 150 is the first line S １ , 3rd line S ３ Initially, line 4 S ４ It is formed along the second line S, and the connecting portion 141c is the second line S ２ Except for being formed along the same lines, it has the same configuration as the covering portion 141a described above.

[0117] When gas G hits the coated portion 141a-1, the pressure causes the second line S ２ The connecting portion 141c formed along the first line S is bent, １ , 3rd line S ３ Initially, line 4 S ４ At the cut portion 150 formed along the line, the main body portion 141b and the covering portion 141a separate. The deformed covering portion 141a-1 functions as a deflection plate, and the direction of movement of the gas G discharged from the safety valve is along the second line S ２ From the 4th line S ４ It is controlled in the direction toward that direction.

[0118] (Third Embodiment) Next, a battery pack according to the third embodiment of the present invention will be described. The battery pack according to the third embodiment of the present invention differs from the battery pack according to the first embodiment of the present invention in that the cut portion is formed along the second and fourth lines, and the connection portion is formed along the first and third lines. The covering portion of the battery pack according to this third embodiment of the present invention will be described with reference to the drawings.

[0119] Figure 10 is a schematic plan view showing an example of a covering portion in a battery pack according to a third embodiment of the present invention. The contour C of the covering portion 241a shown in Figure 10 is rectangular, and the first point P １ And point P ２ The first line S connecting them １ And, point P, the second point ２ and point P ３ The second line S connecting ２ And, point P, the third point ３ and point P ４ Third line S connecting ３ And, point P, the fourth point４ and point P １ The fourth line S connecting them ４ It is formed by the following. And, along the first direction D, the third line S ３ And the first line S １ They are positioned in that order.

[0120] In the covered portion 241a, the cut portion 250 is the second line S ２ Initially, line 4 S ４ It is formed along the first line S, and the connecting portion 241c is the first line S １ and the third line S ３ It is formed along the lines of the curve. The connecting portion 241c connects the covering portion 241a and the main body portion 241b.

[0121] Next, we will explain the case where high-temperature gas from an abnormal battery cell generated during thermal runaway strikes the coating portion 241a. Figure 11 is a schematic perspective view showing an example of the changes in the coating portion when high-temperature gas strikes the coating portion in a battery pack according to the third embodiment of the present invention.

[0122] As shown in Figure 11, when gas G hits the coating portion 241a, the first line S １ and the third line S ３ The connecting portion 241c formed along the line acts as a fulcrum, causing the covering portion 241a to bend so that it is convex in the direction of gas G discharge. Then, at the cut portion 250, the main body portion 241b and the covering portion 241a separate, forming a passage for gas G. In this case, the covering portion 241a functions as a deflection plate, and the direction of movement of the gas G discharged from the safety valve is along the second line S ２ From the 4th line S ４ Direction toward, or the fourth line S ４ From the second line S ２ It is controlled in the direction toward the gas discharge. Furthermore, even if the covering portion 241a is bent so as to be convex in the direction of gas discharge, the covering portion 241a is present between the safety valve and the case, so it is possible to prevent the gas G discharged from the safety valve from directly hitting the case.

[0123] In the battery pack according to the third embodiment of the present invention, the shape of the covering portion that can be used is the same as the shape of the covering portion that can be used in the battery pack according to the first embodiment of the present invention.

[0124] (Fourth Embodiment) Next, a battery pack according to the fourth embodiment of the present invention will be described. The battery pack according to the fourth embodiment of the present invention differs from the battery pack according to the first embodiment of the present invention in that the cut portion is formed along the first and third lines, and the connection portion is formed along the second and fourth lines. The covering portion of the battery pack according to this fourth embodiment of the present invention will be described with reference to the drawings.

[0125] Figure 12 is a schematic plan view showing an example of a covering portion in a battery pack according to the fourth embodiment of the present invention. The contour C of the covering portion 341a shown in Figure 12 is rectangular, and the first point P １ And point P ２ The first line S connecting them １ And, point P, the second point ２ and point P ３ The second line S connecting ２ And, point P, the third point ３ and point P ４ Third line S connecting ３ And, point P, the fourth point ４ and point P １ The fourth line S connecting them ４ It is formed by the following. And, along the first direction D, the third line S ３ And the first line S １ They are positioned in that order.

[0126] In the covered portion 341a, the cut portion 350 is the first line S １ and the third line S ３ It is formed along the second line S, and the connecting portion 341c is the second line S ２ Initially, line 4 S ４ It is formed along the lines of the curve. The connecting portion 341c connects the covering portion 341a and the main body portion 341b.

[0127] Next, we will explain the case where high-temperature gas from an abnormal battery cell generated during thermal runaway strikes the coating portion 341a. Figure 13 is a schematic perspective view showing an example of the changes in the coating portion when high-temperature gas strikes the coating portion in a battery pack according to the fourth embodiment of the present invention.

[0128] As shown in Figure 13, when gas G hits the coating portion 341a, the second line S ２Initially, line 4 S ４ The connecting portion 341c formed along the first line S acts as a fulcrum, causing the covering portion 341a to bend so that it is convex in the direction of gas G discharge. Then, at the cut portion 350, the main body portion 341b and the covering portion 341a separate, forming a passage for gas G. In this case, the covering portion 341a functions as a deflection plate, and the direction of movement of the gas G discharged from the safety valve is along the first line S １ From the 3rd line S ３ Direction toward, or the third line S ３ From the first line S １ It is controlled in the direction toward the gas discharge. Furthermore, even if the covering portion 341a is bent so as to be convex in the direction of gas discharge, the covering portion 341a is present between the safety valve and the case, so it is possible to prevent the gas G discharged from the safety valve from directly hitting the case.

[0129] In the battery pack according to the fourth embodiment of the present invention, the shape of the covering portion that can be used is the same as the shape of the covering portion that can be used in the battery pack according to the first embodiment of the present invention.

[0130] (Fifth Embodiment) Next, a battery pack according to the fifth embodiment of the present invention will be described. In the battery pack according to the fifth embodiment of the present invention, a first notch is formed inside the contour of the covering portion, and the first notch is formed on a straight line that intersects the first line and the third line, which is different from the battery pack according to the fourth embodiment of the present invention. The covering portion of the battery pack according to this fifth embodiment of the present invention will be described with reference to the drawings.

[0131] Figure 14 is a schematic plan view showing an example of a covering portion in a battery pack according to the fifth embodiment of the present invention. The contour C of the covering portion 441a shown in Figure 14 is rectangular, and the first point P １ And point P ２ The first line S connecting them １ And, point P, the second point ２ and point P ３ The second line S connecting ２ And, point P, the third point ３ and point P ４ Third line S connecting ３ And, point P, the fourth point ４ and point P １ The fourth line S connecting them４ It is formed by the following. And, along the first direction D, the third line S ３ And the first line S １ They are positioned in that order.

[0132] In the covered portion 441a, the cut portion 450 is the first line S １ and the third line S ３ It is formed along the second line S, and the connecting portion 441c is the second line S ２ Initially, line 4 S ４ It is formed along the lines of the curve. The connecting portion 441c connects the covering portion 441a and the main body portion 441b.

[0133] In the covered portion 441a, the first cut portion 460 is the first line S １ and the third line S ３ It is formed on a straight line α that intersects with the first line S. １ and the third line S ３ It is in contact with the cut portion 450 formed along the curve.

[0134] Next, we will explain the case where high-temperature gas from an abnormal battery cell generated during thermal runaway strikes the coating portion 441a. Figure 15 is a schematic perspective view showing an example of the changes in the coating portion when high-temperature gas strikes the coating portion in a battery pack according to the fifth embodiment of the present invention.

[0135] As shown in Figure 15, when the gas G hits the coating portion 441a, the coating portion 441a is divided along the first cut portion 460, and the second line S ２ Initially, line 4 S ４ The connecting portion 441c formed along the first line S is bent, １ and the third line S ３ At the cut portion 450 formed along the second line S, the main body portion 441b and the covering portion 441a separate. In this case, the covering portion 441a functions as a deflection plate, directing the movement of the gas G discharged from the safety valve along the second line S ２ From the 4th line S ４ The direction toward, and the fourth line S ４ From the second line S ２ It can be controlled to move in that direction.

[0136] In the above covering portion 441a, the first cut portion 460 is the first line S１ and the third line S ３ In the first embodiment of the battery pack, the first notch and the cut portion 450 formed along the first notch were in contact, but in the fifth embodiment of the present invention, the first notch and the cut portion do not need to be in contact. In this case, when gas hits the covering portion, high pressure is required for the covering portion to be divided along the first notch. The ease with which the covering portion can be deformed can be adjusted by adjusting the position of the first notch depending on the expected gas pressure during thermal runaway and the material and size of the first insulation sheet.

[0137] In the battery pack according to the fifth embodiment of the present invention, the shape of the covering portion that can be used is the same as the shape of the covering portion that can be used in the battery pack according to the first embodiment of the present invention.

[0138] (Sixth Embodiment) The battery pack according to the sixth embodiment of the present invention differs from the battery pack according to the first embodiment of the present invention in that the heat insulating material further includes a second heat insulating sheet and an adhesive layer for bonding the second heat insulating sheet to the first heat insulating sheet, and the heat insulating material is arranged such that the second heat insulating sheet is located on the module side and the first heat insulating sheet is located on the case side. This battery pack according to the sixth embodiment of the present invention will be described with reference to the drawings.

[0139] Figure 16 is a schematic cross-sectional view showing an example of a battery pack according to the sixth embodiment of the present invention. The battery pack 510 shown in Figure 16 differs from the battery pack according to the first embodiment in that the heat insulating material 540 consists of a first heat insulating sheet 541, a second heat insulating sheet 542, and an adhesive layer (not shown) that adheres the first heat insulating sheet 541 and the second heat insulating sheet 542 together. The heat insulating material 540 is arranged such that the second heat insulating sheet 542 is located on the module 20 side and the first heat insulating sheet 541 is located on the case 30 side.

[0140] With such a second insulation sheet 542 in place, the gas G released from the abnormal battery cell passes through the second insulation sheet 542 before reaching the first insulation sheet 541. The gas G then thermally decomposes the adhesive layer, causing the covering portion 541a to peel off from the second insulation sheet, and the gas pressure separates the covering portion 541a from the main body portion 541b. Furthermore, the temperature and pressure of the gas G decrease as it passes through the second insulation sheet 542. Therefore, even if the gas G passes over the area where the covering portion 541a was located on the first insulation sheet 541 and comes into contact with the case 30, the case 30 is less likely to be heated or damaged by the gas G.

[0141] In the battery pack 510, it is preferable that the adhesive layer includes an organic adhesive layer. When the adhesive layer includes an organic adhesive layer, it becomes easier for the adhesive layer to decompose thermally when high-temperature gas G from an abnormal battery cell reaches it. The organic adhesive layer is preferably thermally decomposed at 80°C or higher, and examples include adhesive layers containing polyamide-based organic materials.

[0142] In the battery pack 510, the second insulation sheet 542 has a second notch formed therein that extends from the main surface to which the first insulation sheet 541 is bonded to the other main surface, and when the insulation material 540 is viewed from above from the first insulation sheet 541 side, it is preferable that at least a part of the second notch is located inside the covering portion 541a. When the second insulation sheet 542 has a second notch formed therein, high-temperature gas G from the module 20 side can easily reach the covering portion 541a through the second notch. When the insulation material 540 is viewed from above from the first insulation sheet 541 side, the second notch may be located only inside the covering portion 541a, or it may be located so as to intersect with the contour of the covering portion 541a.

[0143] In the battery pack 510, when the heat insulating material 540 is viewed from above from the first heat insulating sheet 541 side, the second cut portion may be formed in a linear shape or a curved shape, but it is preferable that it be formed in a linear shape. A linear second cut portion can be easily formed with a cutter or the like.

[0144] In the battery pack 510, the second insulation sheet 542 may have multiple second notches. Also, in the battery pack 510, when the insulation material 540 is viewed from the first insulation sheet 541 side, the multiple second notches may be separated from each other or may intersect each other. In either case, gas G generated from an abnormal battery cell can easily reach the first insulation sheet 541 quickly through the second notches.

[0145] In the battery pack 510, the first heat insulating sheet 541 can be the first heat insulating sheet used in the battery packs according to the first to fifth embodiments of the present invention described above.

[0146] In the battery pack 510, if the first heat insulating sheet 541 has at least one first notch formed therein, at least a portion of which is inside the contour of the covering portion (i.e., if the first heat insulating sheet 541 is the first heat insulating sheet used in the battery pack according to the fifth embodiment of the present invention), then when the heat insulating material 540 is viewed from the first heat insulating sheet 541 side, the first notch and the second notch may overlap and have the same shape. Such a first notch and a second notch can be formed simultaneously by punching them out while the first heat insulating sheet 541 and the second heat insulating sheet 542 are stacked on top of each other. Note that the first notch and the second notch do not have to overlap and may have different shapes.

[0147] In the battery pack 510, the second heat insulating sheet 542 may be at least one selected from the group consisting of inorganic fiber mat, inorganic fiber paper, and inorganic fiber cloth. Among these, the inorganic fiber mat is preferred. These can be easily molded, and the inorganic fiber mat exhibits excellent performance as the second heat insulating sheet.

[0148] The thickness of the inorganic fiber mat is preferably 0.5 to 10 mm, and more preferably 1 to 4 mm. If the inorganic fiber mat is less than 0.5 mm thick, the gas temperature and pressure do not decrease easily as the gas passes through the mat. As a result, the gas reaches the case quickly at a high temperature, causing the case to deteriorate easily. If the inorganic fiber mat is more than 10 mm thick, it becomes too thick, making it difficult to miniaturize the entire battery pack.

[0149] The bulk density of inorganic fiber mats is 0.1 to 1.0 g / cm³. ３ Preferably, it is 0.2 to 0.7 g / cm³. ３ It is more preferable that the bulk density of the inorganic fiber mat be 0.1 g / cm³. ３ If the bulk density is less than 1.0 g / cm³, the gaps between the inorganic fibers become larger, so the gas temperature and pressure do not decrease easily as the gas passes through the inorganic fiber mat. As a result, the gas reaches the case with high pressure while still at a high temperature, making the case more prone to deterioration. ３ If the temperature exceeds a certain level, the gas will have difficulty passing through the inorganic fiber mat, causing the high-temperature gas to remain inside the battery cell and making it difficult for the temperature inside the battery cell to decrease. This makes it easier for a chain reaction of thermal runaway to occur.

[0150] The inorganic fiber mat is preferably made by processing inorganic fibers into a mat shape, which include at least one fiber selected from silica fibers, glass fibers, alumina fibers, aluminosilicate fibers, basalt fibers, rock wool, and biosoluble fibers. Inorganic fiber mats made of such materials can be easily processed.

[0151] The inorganic fiber mat may be made by processing inorganic fibers containing fibers with a melting point of 1000°C or higher into a mat shape. When the inorganic fiber mat contains fibers with a melting point of 1000°C or higher, the inorganic fibers have high heat resistance, so even if high-temperature gas from an abnormal battery cell reaches the inorganic fiber mat, the inorganic fiber mat will be less likely to deteriorate.

[0152] The inorganic fiber mat may be made by processing inorganic fibers, including fibers with a melting point of less than 1000°C, into a mat shape. If the inorganic fiber mat contains fibers with a melting point of less than 1000°C, when high-temperature gas from an abnormal battery cell reaches the inorganic fiber mat, the inorganic fiber mat will melt, making it easier for gas channels to form.

[0153] Furthermore, the preferred forms of inorganic fiber paper and inorganic fiber cloth as the second heat insulating sheet 542 are the same as those described in the first embodiment of the present invention.

[0154] This specification describes the following inventions:

[0155] (1) The present invention relates to a battery pack comprising: a module having a plurality of battery cells, each provided with a safety valve; a case housing the module; and a heat insulating material provided between the module and the case, wherein the case has an exhaust duct formed to extend in a first direction between the heat insulating material and the case, and an exhaust port formed on the first direction side of the case that communicates between the exhaust duct and the outside of the case, and the heat insulating material includes a first heat insulating sheet, and when the first heat insulating sheet is viewed in plan, the first heat insulating sheet consists of a plurality of covering parts that cover each of the plurality of safety valves, and a main body part other than the covering parts, and one of the covering parts covers at least a part of one of the safety valves The battery pack is characterized in that it is positioned to overlap with the above, the covering portion has a cut portion formed along the contour of the covering portion and a connecting portion formed along the contour of the covering portion other than the cut portion, the contour of the covering portion is formed by a first line connecting the first and second points, a second line connecting the second and third points, a third line connecting the third and fourth points, and a fourth line connecting the fourth point and the first point, the first line, the second line, the third line and the fourth line are each line segments or curves, the third line and the first line are positioned in order along the first direction, and the cut portion is formed along the first line and the third line, or along the second line and the fourth line.

[0156] The present invention (2) is a battery pack according to the present invention (1), wherein the figure formed by connecting the first point, the second point, the third point, and the fourth point in order with line segments is a rectangle.

[0157] The present invention (3) is a battery pack according to the present invention (1), wherein the cut portion is formed along the first line and the third line.

[0158] The present invention (4) is a battery pack according to the present invention (3), wherein the cut portion is formed along the second line and the connecting portion is formed along the fourth line, or the cut portion is formed along the fourth line and the connecting portion is formed along the second line.

[0159] The present invention (5) is a battery pack according to the present invention (4), wherein the cut portion is formed along the second line, and the cut portions formed along the first line, the second line, and the third line are continuous.

[0160] The present invention (6) is a battery pack according to the present invention (4), wherein the cut portion is formed along the fourth line, and the cut portions formed along the first line, the third line, and the fourth line are continuous.

[0161] The present invention (7) is a battery pack according to the present invention (3), wherein the connection portion is formed along the second and fourth lines.

[0162] The present invention (8) is a battery pack according to the present invention (7), wherein the first heat insulating sheet has at least one first notch formed therein, at least a portion of which is inside the contour of the covering portion, and the first notch is formed on a straight line intersecting the first line and the third line.

[0163] The present invention (9) is a battery pack according to the present invention (8), wherein the first notch is formed to be in contact with the cut portion.

[0164] The present invention (10) is a battery pack according to the present invention (1), wherein the cut portion is formed along the second line and the fourth line.

[0165] The present invention (11) is a battery pack according to the present invention (10), wherein the cut portion is further formed along the first line and the connecting portion is formed along the third line.

[0166] The present invention (12) is a battery pack according to the present invention (11), wherein the cut portions formed along the first line, the second line, and the fourth line are continuous.

[0167] The present invention (13) is a battery pack according to the present invention (10), wherein the connection portion is formed along the first line and the third line.

[0168] The present invention (14) is a battery pack according to any one of the present inventions (1) to (13), wherein the total length of the cut portions is longer than the total length of the connected portions.

[0169] The present invention (15) is a battery pack according to any one of the present inventions (1) to (14), wherein the thickness of the first heat insulating sheet is 0.05 to 2.0 mm.

[0170] The present invention (16) is a battery pack according to any one of the present inventions (1) to (15), wherein the plan view shape of the covering portion is at least one selected from the group consisting of a square, a circle, an ellipse, and a racetrack shape.

[0171] The present invention (17) is a battery pack according to any one of the present inventions (1) to (16), wherein the first heat insulating sheet is at least one selected from the group consisting of mica sheet, heat-resistant resin sheet, inorganic fiber paper, and inorganic fiber cloth.

[0172] The present invention (18) is a battery pack according to any one of the present inventions (1) to (17), wherein the heat insulating material further comprises a second heat insulating sheet and an adhesive layer for bonding the second heat insulating sheet to the first heat insulating sheet, and the heat insulating material is arranged such that the second heat insulating sheet is located on the module side and the first heat insulating sheet is located on the case side.

[0173] The present invention (19) is a battery pack according to the present invention (18), wherein the second heat insulating sheet has a second notch formed therein that is continuous from the main surface to which the first heat insulating sheet is adhered to the other main surface, and when the heat insulating material is viewed in plan view from the first heat insulating sheet side, at least a part of the second notch is located inside the covering portion.

[0174] The present invention (20) is a battery pack according to the present invention (19), wherein when the heat insulating material is viewed in plan view from the first heat insulating sheet side, the second cut portion is formed in a linear shape.

[0175] The present invention (21) is a battery pack according to the present invention (19) or (20), wherein the first heat insulating sheet has at least one first notch formed therein, at least a part of which is inside the contour of the covering portion, and when the heat insulating material is viewed in plan view from the first heat insulating sheet side, the first notch and the second notch overlap in the same shape.

[0176] The present invention (22) is a battery pack according to any one of the present inventions (18) to (21), wherein the second heat insulating sheet is at least one selected from the group consisting of inorganic fiber mat, inorganic fiber paper, and inorganic fiber cloth.

[0177] The present invention (23) is a sheet-like thermal insulation material comprising a main body and a covering portion formed on the inside of the main body, wherein the covering portion has a cut portion formed along the contour of the covering portion and a connecting portion formed along the contour of the covering portion other than the cut portion, the contour of the covering portion is formed by a first line connecting a first point and a second point, a second line connecting a second point and a third point, a third line connecting a third point and a fourth point, and a fourth line connecting a fourth point and a first point, the first line, the second line, the third line and the fourth line are each line segments or curves, the third line and the first line are positioned in order along the first direction, and the cut portion is formed along the first line and the third line, or along the second line and the fourth line, characterized in that the thermal insulation material is formed along the first line and the third line, or along the second line and the fourth line.

[0178] 10, 510 Battery pack 20 Module 20a Connection module component 20b Busbar 21 Battery cell 21a Abnormal battery cell 22, 22a Safety valve 23 Terminal 30 Case 31 Housing section 31b Bottom section 31s Side wall 32 Cover section 33 Exhaust duct 34 Exhaust port 40, 540 Insulation material 41, 541 First insulation sheet 41a, 41a-A, 41a-B, 41a-C, 141a, 141a-1, 241a, 341a, 441a, 541a Covering section 41b, 141b, 241b, 341b, 441b, 541b Main body section 41c, 141c, 241c, 341c, 441c Connection section 50, 150, 250, 350, 450 Cutting section 460 First cut section 542 Second insulation sheet D First direction P １ 1st point P ２ Second point P ３ Third point P ４ 4th point S １ 1st line S ２ 2nd line S ３ 3rd line S ４ Fourth line

Claims

1. A battery pack comprising: a module having a plurality of battery cells, each provided with a safety valve; a case housing the module; and a heat insulating material provided between the module and the case, wherein the case has an exhaust duct formed to extend in a first direction between the heat insulating material and the case; and an exhaust port formed on the first direction side of the case, communicating between the exhaust duct and the outside of the case; the heat insulating material includes a first heat insulating sheet; when the first heat insulating sheet is viewed from above, the first heat insulating sheet consists of a plurality of covering portions that cover each of the plurality of safety valves, and a main body portion other than the covering portions; each covering portion is positioned to overlap with at least a part of one of the safety valves; the covering portion has a cut portion formed along the contour of the covering portion, and a connecting portion formed along the contour of the covering portion other than the cut portion; the contour of the covering portion has a first line connecting a first point and a second point; a second line connecting a second point and a third point; and a third line connecting a third point and a fourth point. A battery pack characterized in that it is formed by a fourth line connecting a fourth point and a first point, the first line, the second line, the third line and the fourth line are each line segments or curves, the third line and the first line are positioned sequentially along the first direction, and the cut portion is formed along the first line and the third line, or along the second line and the fourth line.

2. The battery pack according to claim 1, wherein the figure formed by connecting the first point, the second point, the third point, and the fourth point in order with line segments is a rectangle.

3. The battery pack according to claim 1, wherein the cut portion is formed along the first line and the third line.

4. The battery pack according to claim 3, wherein the cut portion is formed along the second line and the connecting portion is formed along the fourth line, or the cut portion is formed along the fourth line and the connecting portion is formed along the second line.

5. The battery pack according to claim 4, wherein the cut portion is formed along the second line, and the cut portions formed along the first line, the second line and the third line are continuous.

6. The battery pack according to claim 4, wherein the cut portion is formed along the fourth line, and the cut portions formed along the first line, the third line, and the fourth line are continuous.

7. The battery pack according to claim 3, wherein the connection portion is formed along the second and fourth wires.

8. The battery pack according to claim 7, wherein the first heat insulating sheet has at least one first notch formed therein, at least a portion of which is inside the contour of the covering portion, and the first notch is formed on a straight line intersecting the first line and the third line.

9. The battery pack according to claim 8, wherein the first notch is formed to be in contact with the cut portion.

10. The battery pack according to claim 1, wherein the cut portion is formed along the second and fourth lines.

11. The battery pack according to claim 10, wherein the cut portion is further formed along the first line, and the connecting portion is formed along the third line.

12. The battery pack according to claim 11, wherein the cut portions formed along the first line, the second line, and the fourth line are continuous.

13. The battery pack according to claim 10, wherein the connection portion is formed along the first and third lines.

14. The battery pack according to any one of claims 1 to 13, wherein the total length of the cut portions is longer than the total length of the connected portions.

15. The battery pack according to any one of claims 1 to 14, wherein the thickness of the first heat insulating sheet is 0.05 to 2.0 mm.

16. The battery pack according to any one of claims 1 to 15, wherein the plan view shape of the covering portion is at least one selected from the group consisting of a square, a circle, an ellipse, and a racetrack shape.

17. The battery pack according to any one of claims 1 to 16, wherein the first heat insulating sheet is at least one selected from the group consisting of mica sheet, heat-resistant resin sheet, inorganic fiber paper, and inorganic fiber cloth.

18. The battery pack according to any one of claims 1 to 17, wherein the insulating material further comprises a second insulating sheet and an adhesive layer for bonding the second insulating sheet to the first insulating sheet, and the insulating material is arranged such that the second insulating sheet is located on the module side and the first insulating sheet is located on the case side.

19. The battery pack according to claim 18, wherein the second heat insulating sheet has a second notch formed therein that is continuous from the main surface to which the first heat insulating sheet is adhered to the other main surface, and when the heat insulating material is viewed in plan from the first heat insulating sheet side, at least a part of the second notch is located inside the covering portion.

20. The battery pack according to claim 19, wherein the second cut portion is formed in a linear shape when the insulating material is viewed in plan view from the first insulating sheet side.

21. The battery pack according to claim 19 or 20, wherein the first heat insulating sheet has at least one first notch formed therein, at least a portion of which is inside the contour of the covering portion, and when the heat insulating material is viewed in plan view from the first heat insulating sheet side, the first notch and the second notch overlap in the same shape.

22. The battery pack according to any one of claims 18 to 21, wherein the second heat insulating sheet is at least one selected from the group consisting of inorganic fiber mat, inorganic fiber paper, and inorganic fiber cloth.

23. A sheet-like thermal insulation material comprising a main body and a covering portion formed on the inside of the main body, wherein the covering portion has a cut portion formed along the contour of the covering portion and a connecting portion formed along the contour of the covering portion other than the cut portion, the contour of the covering portion is formed by a first line connecting a first point and a second point, a second line connecting a second point and a third point, a third line connecting a third point and a fourth point, and a fourth line connecting a fourth point and a first point, the first line, the second line, the third line and the fourth line are each line segments or curves, the third line and the first line are positioned in order along the first direction, and the cut portion is formed along the first line and the third line, or along the second line and the fourth line.

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