Battery pack

Abstract

This invention provides a battery pack capable of preventing a chain reaction of thermal runaway caused by high-temperature gases from abnormal battery cells during thermal runaway. The battery pack of this invention comprises: a module having a plurality of battery cells each equipped with a safety valve; a housing housing the module; and a thermal insulation material disposed between the module and the housing. The thermal insulation material comprises a first thermal insulation sheet having a plurality of openings penetrating the first thermal insulation sheet, and a cover sheet covering at least a portion of each of the plurality of openings is disposed thereon. The cover sheet is bonded to the first thermal insulation sheet by an adhesive. When the first thermal insulation sheet is viewed from above, one of the openings overlaps with at least a portion of one of the safety valves.

Description

Technical Field

[0001] This invention relates to battery packs. Background Technology

[0002] In battery packs containing multiple battery cells housed in a casing, high-temperature gases and flames can sometimes be generated during thermal runaway. These gases and flames can spread to the surrounding area, potentially inducing further thermal runaway.

[0003] To prevent the chain reaction of thermal runaway and to release the high-temperature gas generated during thermal runaway, safety valves have always been installed in the module.

[0004] In addition, if the high-temperature gas released from the safety valve comes into direct contact with the casing, the temperature of the casing will rise, sometimes causing a thermal effect around the battery pack.

[0005] In order to prevent high-temperature gas from coming into direct contact with the casing, thermal insulation material was previously placed between the module and the casing.

[0006] As such a battery pack, Patent Document 1 discloses an energy storage device comprising: an energy storage stack including a plurality of energy storage units, each having an exhaust valve on its upper surface; an upper housing covering the energy storage stack from above; and a first heat-resistant sheet and a second heat-resistant sheet having heat resistance relative to exhaust gas discharged from the exhaust valves and disposed between the upper housing and the energy storage stack. The first heat-resistant sheet has a plurality of holes at a position where it overlaps with each of the exhaust valves in the vertical direction, and the second heat-resistant sheet is disposed above the first heat-resistant sheet in such a way as to cover the plurality of holes.

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: Japanese Patent Application Publication No. 2023-59480 Summary of the Invention

[0010] The problem that the invention aims to solve

[0011] In the energy storage device (battery pack) described in Patent Document 1, during thermal runaway, high-temperature gas discharged from the discharge valve of the abnormal battery cell blows through the holes of the first heat-resistant sheet towards the second heat-resistant sheet. This pushes the second heat-resistant sheet upwards, separating it from the first heat-resistant sheet, thus forming a gas flow path between the two sheets. Because the gas is blocked by the second heat-resistant sheet, it does not reach the upper casing, preventing damage to the upper casing. Furthermore, the first heat-resistant sheet prevents the gas intercepted by the second heat-resistant sheet from contacting adjacent cells, thus suppressing temperature rise in adjacent cells.

[0012] However, in the energy storage device (battery pack) described in Patent Document 1, because the high-temperature gas is blocked by the second heat-resistant sheet, the high-temperature gas may flow back through other holes in the first heat-resistant sheet from the discharge valve of the normal battery cell adjacent to the abnormal battery cell. In the event of high-temperature gas backflow, the normal cell may experience thermal runaway.

[0013] That is, in the energy storage device (battery pack) described in Patent Document 1, there is a problem that thermal runaway cannot be adequately prevented.

[0014] This invention was made to solve the above-mentioned problems. The purpose of this invention is to provide a battery pack that can prevent the chain reaction of thermal runaway caused by high-temperature gas from abnormal battery cells during thermal runaway.

[0015] Methods for solving problems

[0016] The battery pack of the present invention comprises: a module having a plurality of battery cells each having a safety valve; a housing for housing the module; and a heat-insulating material disposed between the module and the housing, characterized in that the heat-insulating material comprises a first heat-insulating sheet having a plurality of openings through the first heat-insulating sheet, and a cover sheet covering at least a portion of each of the plurality of openings being disposed thereon, the cover sheet being bonded to the first heat-insulating sheet by an adhesive, and in a top-view perspective view of the first heat-insulating sheet, one of the openings is located at a position overlapping at least a portion of one of the safety valves.

[0017] In the battery pack of the present invention, it is possible to prevent the chain reaction of thermal runaway caused by high-temperature gases from abnormal battery cells generated during thermal runaway. The principle is explained below.

[0018] In the battery pack of this invention, a safety valve is provided in each module. Therefore, when a high-temperature gas is generated due to thermal runaway of the battery cell, the gas is discharged from the safety valve. Then, the gas released from the safety valve reaches the heat insulation material.

[0019] The insulation material includes a first insulation sheet, having an opening extending through the first insulation sheet.

[0020] In addition, when the first insulation sheet is viewed from above, the opening is located at a position that overlaps with at least a portion of the safety valve.

[0021] Therefore, the gas discharged from the safety valve reaches the vicinity of the opening of the first insulation sheet.

[0022] A cover sheet is provided at the opening to cover at least a portion of the opening, and the cover sheet is bonded to the first insulation sheet by an adhesive.

[0023] The gas reaching the vicinity of the opening in the first insulation sheet is at a high temperature, thus thermally decomposing the adhesive used to bond the cover sheet. Consequently, the bond between the cover sheet and the first insulation sheet weakens.

[0024] Additionally, air pressure is applied to the cover sheet from the module side toward the housing side.

[0025] As a result, the cover sheet peeled off from the first insulation sheet.

[0026] Then, the gas is released between the insulation material and the shell through the opening of the first insulation sheet.

[0027] During this process, the temperature of the hot gas decreases, and the gas pressure also decreases. Therefore, even if the gas is released from the opening and comes into contact with the shell, the shell is not easily heated by the gas, and it is also not easily damaged.

[0028] In addition, the gas released from the opening of the first insulation sheet diffuses between the insulation material and the shell, and also reaches other openings of the first insulation sheet.

[0029] However, since a cover sheet is provided inside the other openings of the first insulation sheet, even if gas reaches the other openings of the first insulation sheet, it can prevent gas from flowing back from the other openings of the first insulation sheet to the module side.

[0030] Based on this principle, this invention prevents high-temperature gases generated from abnormal battery cells during thermal runaway from reaching other battery cells. This prevents a cascading effect of thermal runaway.

[0031] In the battery pack of the present invention, it is preferable that at least one of the cover sheets is disposed inside each of the plurality of openings, and it is preferable that a plurality of the cover sheets are disposed inside the openings.

[0032] If the cover sheet is positioned inside the opening, it can be easily peeled off from the first insulation sheet.

[0033] In the battery pack of the present invention, it is preferable that a plurality of the cover sheets are disposed inside each of the plurality of openings.

[0034] To prevent the backflow of high-temperature gas from the housing side, it is preferable that there is no gap between the opening and the cover plate.

[0035] When the cover sheet is arranged inside the opening without creating a gap between the opening and the cover sheet, the size of each cover sheet becomes smaller when multiple cover sheets are arranged compared to arranging a one-piece cover sheet.

[0036] When an integral cover is placed at the opening, if the integral cover peels off due to gas from the module side, the integral cover, being large, may sometimes block the gas flow path and hinder gas diffusion.

[0037] On the other hand, when multiple covers are arranged at the opening, when the multiple covers are stripped by gas from the module side, one cover is smaller, so each cover does not easily obstruct the diffusion of gas.

[0038] In the battery pack of the present invention, it is preferable that at least a portion of the plurality of cover sheets are arranged in contact with each other. In this case, it is preferable that the contacting portions of the cover sheets are formed in a straight line.

[0039] Furthermore, in the battery pack of the present invention, it is preferable that the cover sheet is configured such that at least a portion of it contacts the contour of the opening.

[0040] If the cover is configured in this way, it is easy to prevent gas from flowing back through the gaps between the cover sheets and the gap between the cover sheets and the opening.

[0041] In the battery pack of the present invention, it is preferable that the cover sheet is configured to cover the outline of the opening from the housing side.

[0042] If the cover is configured in this way, no gap will be generated between the cover and the opening, which easily prevents gas from flowing back between the cover and the opening.

[0043] In the battery pack of the present invention, the top view shape of the opening is preferably selected from at least one shape chosen from the group consisting of triangles, quadrilaterals, hexagons, circles, ellipses and racetrack shapes.

[0044] This type of opening can be easily formed.

[0045] In the battery pack of the present invention, the first heat-insulating sheet may be a mica sheet or a heat-resistant resin sheet.

[0046] These materials are suitable as primary insulation sheets.

[0047] In the battery pack of the present invention, it is preferable that the cover sheet is made of the same material as the first heat-insulating sheet.

[0048] By punching out an integral sheet in a way that forms an opening, it is possible to simultaneously produce the first insulation sheet and the cover sheet.

[0049] In the battery pack of the present invention, the adhesive preferably comprises an organic adhesive.

[0050] If the adhesive contains organic adhesives, it is prone to thermal decomposition when high-temperature gases from abnormal battery cells reach the cover sheet.

[0051] Therefore, the cover sheet can be easily peeled off from the first insulation sheet.

[0052] In the battery pack of the present invention, the heat insulation material may also include a second heat insulation sheet, which is laminated on the first heat insulation sheet such that it covers the opening from the housing side.

[0053] Such a battery pack is configured such that the first heat insulation sheet is located on the lower side in the vertical direction and the second heat insulation sheet is located on the upper side in the vertical direction.

[0054] In this battery pack configuration, the safety valve is located vertically upwards, so the high-temperature gas from the abnormal battery cell is released vertically upwards.

[0055] Then, the gas reaches the second insulation sheet through the opening formed in the first insulation sheet.

[0056] The gas is blocked by the second insulating sheet. As a result, the gas is prevented from coming into contact with the casing.

[0057] Furthermore, the second insulation sheet is pushed upwards by the gas, moving away from the first insulation sheet. As a result, the gas diffuses through the gap formed between the second and first insulation sheets. Moreover, the temperature and pressure of the gas decrease.

[0058] In the battery package of the present invention, the housing may have a receiving portion consisting of a bottom and a side wall portion and a cover portion covering the receiving portion, and the safety valve may be configured to be located on the bottom side or on the cover side.

[0059] When configuring the battery pack of the present invention, from the viewpoint of failure protection, the battery pack is sometimes configured such that the safety valve is located on the upper or lower side of the vertical direction.

[0060] Battery packs are mostly configured with the bottom of the casing or the cover located on the lower side. Therefore, if the safety valve is configured with the bottom or cover located on the lower side of the casing, it is easy for the safety valve to be located on the upper or lower side in the vertical direction.

[0061] Invention Effects

[0062] According to the present invention, a battery pack is provided that can prevent a chain reaction of thermal runaway caused by high-temperature gases from abnormal battery cells generated during thermal runaway. Attached Figure Description

[0063] Figure 1AThis is a perspective view schematically illustrating an example of a battery pack according to a first embodiment of the present invention.

[0064] Figure 1B It is along Figure 1A A cross-sectional view along line AA.

[0065] Figure 1C yes Figure 1A The diagram shown is an exploded view of the battery pack.

[0066] Figure 2A This is a schematic cross-sectional view illustrating a safety valve of a battery pack according to a first embodiment of the present invention and an example of its vicinity.

[0067] Figure 2B Viewed from the side of the insulation material Figure 2A The safety valve shown is shown in top view.

[0068] Figure 3A The diagram illustrates the principle of the chain reaction that prevents thermal runaway in the event of thermal runaway in a battery cell in the battery pack of the first embodiment of the present invention.

[0069] Figure 3B The diagram illustrates the principle of the chain reaction that prevents thermal runaway in the event of thermal runaway in a battery cell in the battery pack of the first embodiment of the present invention.

[0070] Figure 3C The diagram illustrates the principle of the chain reaction that prevents thermal runaway in the event of thermal runaway in a battery cell in the battery pack of the first embodiment of the present invention.

[0071] Figure 4A This is a top view schematically illustrating an example of another shape of mica sheet in a battery pack according to a first embodiment of the present invention.

[0072] Figure 4B This is a top view schematically illustrating an example of another shape of mica sheet in a battery pack according to a first embodiment of the present invention.

[0073] Figure 4C This is a top view schematically illustrating an example of another shape of mica sheet in a battery pack according to a first embodiment of the present invention.

[0074] Figure 4D This is a top view schematically illustrating an example of another shape of mica sheet in a battery pack according to a first embodiment of the present invention.

[0075] Figure 4E This is a top view schematically illustrating an example of another shape of mica sheet in a battery pack according to a first embodiment of the present invention.

[0076] Figure 4FThis is a top view schematically illustrating an example of another shape of mica sheet in a battery pack according to a first embodiment of the present invention.

[0077] Figure 5A This is an enlarged cross-sectional view schematically showing an example of the cross-section of the heat-insulating material of the battery pack according to the second embodiment of the present invention.

[0078] Figure 5B This is an enlarged cross-sectional view schematically showing another example of the cross-section of the heat-insulating material of the battery pack according to the second embodiment of the present invention.

[0079] Figure 6 This is an enlarged cross-sectional view schematically illustrating an example of a battery pack according to a third embodiment of the present invention.

[0080] Figure 7A The diagram illustrates the principle of the chain reaction that prevents thermal runaway in the event of thermal runaway in a battery cell in the battery pack of the third embodiment of the present invention.

[0081] Figure 7B The diagram illustrates the principle of the chain reaction that prevents thermal runaway in the event of thermal runaway in a battery cell in the battery pack of the third embodiment of the present invention.

[0082] Figure 7C The diagram illustrates the principle of the chain reaction that prevents thermal runaway in the event of thermal runaway in a battery cell in the battery pack of the third embodiment of the present invention. Detailed Implementation

[0083] The battery pack of the present invention will now be described in detail. However, the present invention is not limited to the following structure, and can be appropriately modified and applied without changing the spirit of the invention. It should be noted that the present invention also includes combinations of two or more of the preferred configurations of the present invention described below.

[0084] (First Implementation)

[0085] For the battery pack of the first embodiment of the present invention, the case where the first heat-insulating sheet and the cover sheet constituting the heat-insulating material are mica sheets and mica sheets will be described.

[0086] Figure 1A This is a perspective view schematically illustrating an example of a battery pack according to a first embodiment of the present invention.

[0087] Figure 1B It is along Figure 1A A cross-sectional view along line AA.

[0088] Figure 1C yes Figure 1A The diagram shown is an exploded view of the battery pack.

[0089] Figure 1A , Figure 1B and Figure 1C The battery pack 10 shown includes a module 20 having multiple battery cells 21 and a housing 30 for storing the module 20.

[0090] like Figure 1B As shown, in the battery pack 10, a safety valve 22 is provided in each battery cell 21.

[0091] like Figure 1B As shown, the housing 30 has a storage section 31 consisting of a bottom 31b and a side wall 31s, and a cover 32 covering the storage section 31, in which the module 20 is stored.

[0092] In addition, in the battery pack 10, a heat insulation material 40 is provided between the module 20 and the housing 30.

[0093] The battery cell 21 stores electricity, and is preferably a rechargeable secondary battery. Examples of secondary batteries include lithium-ion batteries, nickel-metal hydride batteries, and sodium-ion batteries.

[0094] Figure 1B as well as Figure 1C The battery cell 21 shown is rectangular parallelepiped. However, in the battery pack of the present invention, the battery cell may also be a three-dimensional shape other than a rectangular parallelepiped (e.g., a cube or deformed shape).

[0095] like Figure 1B as well as Figure 1C As shown, in module 20, multiple battery cells 21 are arranged in a row and fixed by connecting module component 20a.

[0096] In addition, such as Figure 1C As shown, the battery cell 21 has a terminal 23, and adjacent battery cells 21 are electrically connected by a busbar 20b disposed on the connection module component 20a through each terminal 23.

[0097] Busbar 20b is a flat, conductive metal component. Examples of materials that can be used for busbar 20b include copper, copper alloys, stainless steel (SUS), and aluminum.

[0098] Busbar 20b can also be fixed to terminal 23 by any fixing means (such as thread fastening, welding, etc.).

[0099] Materials that make up the shell 30 include steel, aluminum, etc. As steel, stainless steel (SUS) is preferred.

[0100] Figure 2A This is a schematic cross-sectional view illustrating a safety valve of a battery pack according to a first embodiment of the present invention and an example of its vicinity.

[0101] Figure 2B Viewed from the side of the insulation material Figure 2A The safety valve shown is shown in top view.

[0102] like Figure 2A As shown, the thermal insulation material 40 is composed of a mica sheet 42, which serves as the first thermal insulation sheet.

[0103] An opening 42a is formed in the mica sheet 42, extending through the mica sheet 42, such as... Figure 2B As shown, four mica sheets 50 serving as cover sheets are arranged inside the opening 42a.

[0104] The mica sheet 50 is bonded to the mica sheet 42 by an adhesive (not shown). That is, the mica sheet 50 is bonded to the inner wall of the opening 42a.

[0105] In addition, such as Figure 2B As shown, when the mica sheet 42 is viewed from above, an opening 42a is located at a position that overlaps with a safety valve 22.

[0106] And, as Figure 2B As shown, the opening 42a is circular. Additionally, the four mica sheets 50 are congruent sectors, which combine to form a circle.

[0107] The four mica sheets 50 are in contact with the outline of the opening 42a and form a circle by contacting each other.

[0108] In addition, the mica sheets 50 can also be bonded to each other at the contact points using an adhesive.

[0109] In battery pack 10, a cascading thermal runaway mechanism can be established to prevent thermal runaway caused by high-temperature gases from abnormal battery cells. The principle behind this mechanism is explained below.

[0110] Figures 3A-3C The diagram illustrates the principle of the chain reaction that prevents thermal runaway in the event of thermal runaway in a battery cell in the battery pack of the first embodiment of the present invention.

[0111] like Figure 3A As shown, when a battery cell 21a experiences thermal runaway and generates high-temperature gas from the battery cell 21a, gas G is discharged from safety valve 22a (in... Figure 3A In the diagram, the symbol "G" represents gas, and an arrow indicates the direction of gas flow.

[0112] Then, the gas released from safety valve 22a reaches the insulation material 40 (mica sheet 42).

[0113] An opening 42a is formed in the mica sheet 42, and when the mica sheet 42 is viewed from above, the opening 42a is located at a position that overlaps with the safety valve 22.

[0114] Therefore, the gas G released from the safety valve 22a reaches the vicinity of the opening 42a of the mica sheet 42.

[0115] A mica sheet 50 is disposed inside the opening 42a of the mica sheet 42, and the mica sheet 50 is bonded to the mica sheet 42 by an adhesive (not shown).

[0116] The gas G reaching the vicinity of the opening 42a of the mica sheet 42 is at a high temperature, thus thermally decomposing the adhesive bonding the mica sheet 50. As a result, the adhesion between the mica sheet 50 and the mica sheet 42 weakens.

[0117] In addition, air pressure is applied to the mica sheet 50 from the module 20 side toward the housing 30 side.

[0118] The result, such as Figure 3B As shown, mica sheet 50 is peeled off from mica sheet 42.

[0119] It should be noted that in the battery pack 10, the mica sheet 50 is separated from the mica sheet 42 and bonded to it by an adhesive as part of other components. That is, the mica sheet 50 is not a part of the mica sheet 42 that is continuous. Therefore, the mica sheet 50 can be reliably peeled off from the mica sheet 42 through the thermal decomposition of the adhesive.

[0120] Then, gas G is released between the insulation material 40 and the shell 30 through the opening 42a of the mica sheet 42.

[0121] During this process, the temperature of gas G decreases, and the gas pressure also decreases. Therefore, even if gas G is released from the opening 42a and comes into contact with the casing 30, the casing 30 is not easily heated by gas G, and it is not easily damaged.

[0122] In addition, such as Figure 3C As shown, the gas G released from the opening 42a of the mica sheet 42 diffuses between the mica sheet 42 and the shell 30, and also reaches other openings 42a of the mica sheet 42.

[0123] However, since mica sheets 50 are disposed inside the other openings 42a of the mica sheet 42, even if gas G reaches the other openings 42a of the mica sheet 42, it is possible to prevent backflow from the other openings 42a of the mica sheet 42 to the module 20 side.

[0124] Based on this principle, in the battery pack 10, it is possible to prevent the high-temperature gas G generated from the abnormal battery cell 21a during thermal runaway from reaching other battery cells 21. Thus, it is possible to prevent the chain reaction of thermal runaway.

[0125] Hereinafter, a preferred embodiment of the heat-insulating material of the battery pack according to the first embodiment of the present invention will be described.

[0126] (Mica sheet)

[0127] The thickness of the mica sheet 42 is preferably 0.05mm to 2.0mm, more preferably 0.1mm to 1.0mm, and even more preferably 0.1mm to 0.5mm.

[0128] If the thickness of the mica sheet is less than 0.05mm, the strength of the mica sheet will be lower and it will be easily damaged.

[0129] If the thickness of the mica sheet exceeds 2.0 mm, the mica sheet becomes too thick, making it difficult to miniaturize the battery pack as a whole.

[0130] In the above Figure 2B In the present invention, the top view shape of the opening 42a formed in the mica sheet 42 is circular. However, in the battery pack of the first embodiment of the present invention, the top view shape of the opening formed in the mica sheet can also be triangular, quadrilateral, hexagonal, elliptical, racetrack, or other shapes.

[0131] This type of opening can be easily formed.

[0132] The area of ​​the top view of the opening 42a is preferably 1.0 cm². 2 ~18cm 2 More preferably 3cm 2 ~12cm 2 .

[0133] If the area of ​​the top view of the opening is less than 1.0 cm² 2 If the gas cannot pass through the opening, it will be difficult for the gas to pass through.

[0134] If the top view area of ​​the opening exceeds 18cm² 2 Therefore, the opening tends to be wider than the area of ​​the mica sheet that the gas reaches. The mica sheets located inside the opening are peeled off from the mica sheet by the gas reaching them, so the mica sheets located in the area where the gas does not reach are not easy to peel off, as will be discussed later.

[0135] In the battery pack 10, when the mica sheet 42 is viewed from above, an opening may be located at a position that overlaps with at least a portion of a safety valve, but preferably an opening is located inside the outline of a safety valve.

[0136] If the opening is located in such a position, the gas released from the safety valve can easily reach the opening.

[0137] (Mica sheet)

[0138] In the above Figure 2B In the heat insulation material 40 shown, each mica sheet 50 is in contact, and each mica sheet 50 is arranged in such a way that it is in contact with the contour of the opening 42a.

[0139] That is, the opening 42a is completely covered by the mica sheet 50 without gaps.

[0140] Therefore, in the battery pack 10, the backflow of high-temperature gas G from the casing 30 side can be prevented.

[0141] In the above Figure 2B In the heat insulation material 40 shown, four mica sheets 50 are disposed inside an opening 42a.

[0142] When the mica sheet 50 is arranged inside the opening 42a without creating a gap between the opening 42a and the mica sheet 50, the size of each mica sheet becomes smaller when multiple mica sheets are arranged compared to arranging a single piece (monolithic) mica sheet.

[0143] When the mica sheet is arranged as a whole (integrated) piece in the opening 42a, if the mica sheet is peeled off due to gas G from the module 20 side, the mica sheet will be large. Therefore, the mica sheet may sometimes block the flow path of gas G and hinder the diffusion of gas.

[0144] On the other hand, if multiple mica sheets 50 are arranged in the opening 42a, and the multiple mica sheets 50 are peeled off due to gas G from the module 20 side, then each mica sheet 50 is small, and therefore each mica sheet 50 is difficult to obstruct the diffusion of gas G.

[0145] As mentioned above, in Figure 2B In the heat insulation material 40 shown, a mica sheet 50 is disposed without gaps in an opening 42a.

[0146] However, in the battery pack of the first embodiment of the present invention, there may be a gap between an opening and a mica sheet disposed inside it, or there may be a gap between the mica sheets themselves.

[0147] Alternatively, in the battery pack of the first embodiment of the present invention, a single piece (integral) of mica sheet may be disposed in an opening.

[0148] With this structure, the number of mica sheets in the overall battery pack is reduced, enabling efficient battery pack manufacturing.

[0149] Next, the shape of the mica sheet will be described when multiple mica sheets are arranged inside the opening.

[0150] Figures 4A to 4F This is a top view schematically illustrating an example of another shape of mica sheet in a battery pack according to a first embodiment of the present invention.

[0151] like Figure 4A As shown, the mica sheet in the battery pack of the first embodiment of the present invention can be two mica sheets 50a.

[0152] Mica sheet 50a is semi-circular. If two mica sheets 50a are combined, they will form a circular shape.

[0153] like Figure 4B As shown, the mica sheet in the battery pack of the first embodiment of the present invention can be four mica sheets 50b1, 50b2, 50b3 and 50b4.

[0154] Mica sheets 50b1, 50b2, 50b3, and 50b4 are arranged in a circular shape from left to right. That is, mica sheets 50b1, 50b2, 50b3, and 50b4 are arranged in a shape that divides the circle into four equal parts by a straight line perpendicular to the horizontal direction.

[0155] like Figure 4C As shown, the mica sheet in the battery pack of the first embodiment of the present invention can be two mica sheets 50c1 and 50c2.

[0156] Mica sheet 50c1 is a ring shape, and mica sheet 50c2 is a circle located inside mica sheet 50c1.

[0157] In this case, by using an adhesive to bond the contact parts of mica sheet 50c1 and mica sheet 50c2, mica sheet 50c2 can be kept in place without falling off.

[0158] like Figure 4D As shown, the mica sheet in the battery pack of the first embodiment of the present invention can be four mica sheets 50d.

[0159] Each mica sheet (50d) is a right-angled isosceles triangle, which together form a square shape.

[0160] like Figure 4E As shown, the mica sheet in the battery pack of the first embodiment of the present invention can be four mica sheets 50e.

[0161] The mica sheet 50e is a congruent rectangle, which forms a square shape when arranged sequentially from left to right.

[0162] That is, each mica sheet 50e is a shape that divides the square into four equal parts by a straight line perpendicular to the horizontal direction.

[0163] like Figure 4F As shown, the mica sheet in the battery pack of the first embodiment of the present invention can be six mica sheets 50f1, 50f2, 50f3, 50f4, 50f5 and 50f6.

[0164] The individual mica sheets are combined to form a runway shape.

[0165] More specifically, it is a shape formed by cutting a runway-shaped mica sheet with a line segment L1 along its long axis and four line segments L2, L3, L4 and L5 connected to line segment L1.

[0166] The points where line segments L1 and L2 connect are the same as the points where line segments L1 and L3 connect, and the angles formed by line segments L1 and L2 and L1 and L3 are the same.

[0167] In addition, the parts where line segment L1 connects to line segment L4 and the parts where line segment L1 connects to line segment L5 are the same, and the angles formed by line segment L1 and line segment L4 and the angles formed by line segment L1 and line segment L5 are the same.

[0168] In the thermal insulation material 40, the mica sheet 50 is bonded to the mica sheet 42 by an adhesive (not shown).

[0169] As an adhesive, it is preferable to contain materials that undergo thermal decomposition upon the arrival of the gas.

[0170] If the adhesive contains such a material, the mica sheet 50 will be easily peeled off when the gas reaches it.

[0171] It should be noted that materials that undergo thermal decomposition upon the arrival of gas are, for example, organic materials with a thermal decomposition temperature of 80°C or higher. More specifically, polyamide-based organic materials can be cited as an example.

[0172] If the adhesive contains polyamide-based organic materials, it is prone to thermal decomposition when the high-temperature gas G from the abnormal battery cell reaches the mica sheet 50.

[0173] Therefore, mica sheet 50 can be easily peeled off from mica sheet 42.

[0174] In the battery pack 10, the mica sheet 42, which serves as the first heat insulation sheet, and the mica sheet 50, which serves as the cover sheet, are both made of the same mica material. As will be described in detail later, such mica sheet 42 and mica sheet 50 can be manufactured simultaneously by punching an integral mica sheet in a manner that forms an opening.

[0175] Furthermore, in the battery pack of the present invention, the cover sheet may be made of the same material as the first heat-insulating sheet, or it may be made of a different material.

[0176] A method for manufacturing the heat-insulating material contained in the battery pack according to the first embodiment of the present invention will be described.

[0177] In manufacturing this insulation material, prepare a mica sheet.

[0178] Next, the mica sheet is punched to produce a mica sheet with an opening and a mica sheet.

[0179] Next, the mica sheet is bonded to the mica sheet (inner wall of the opening) using an adhesive in such a way that the mica sheet is housed inside the formed opening.

[0180] Therefore, it is possible to manufacture heat-insulating materials for the battery packs configured in this invention.

[0181] When multiple mica sheets are used, they can be cut and divided with a knife or similar tool before bonding them.

[0182] Alternatively, slits can be pre-formed on the mica sheet, and the mica sheet can be punched in a manner that includes the slits, thereby forming multiple mica sheets.

[0183] At this point, the mica sheet can be punched by intersecting the outline of the cut portion formed on the mica sheet with the punched portion.

[0184] In this case, a cut remains on the mica sheet. That is, the mica sheet becomes a shape with a cut in a manner that connects to the outline of the opening.

[0185] Alternatively, mica sheets other than the punched mica sheets can be placed inside the opening.

[0186] Next, the use and configuration method of the battery pack according to the first embodiment of the present invention will be described.

[0187] The use of the battery pack of the first embodiment of the present invention is not particularly limited; for example, it can be used as a power source for electric vehicles.

[0188] Furthermore, in the first embodiment of the present invention, the battery pack is preferably configured such that the safety valve of the battery cell is located on the upper or lower side in the vertical direction.

[0189] When a battery pack is configured with the safety valve in this position, the high-temperature gas from abnormal battery cells naturally and rapidly disperses, making it difficult to trigger a chain reaction of thermal runaway. In other words, from a fail-safe perspective, this can be considered the preferred configuration for the battery pack.

[0190] In the battery pack of the first embodiment of the present invention, the safety valve may be configured either on the bottom side or on the cover side.

[0191] As described above, when configuring the battery pack of the first embodiment of the present invention, from the viewpoint of failure protection, the battery pack is sometimes configured such that the safety valve is located on the upper or lower side of the vertical direction.

[0192] Battery packs are mostly configured with the bottom of the casing or the cover located on the lower side. Therefore, if the safety valve is configured with the bottom or cover located on the lower side of the casing, it is easy for the safety valve to be located on the upper or lower side in the vertical direction.

[0193] (Second Implementation)

[0194] Next, the battery pack according to the second embodiment of the present invention will be described.

[0195] The battery pack of the second embodiment of the present invention differs from the battery pack of the first embodiment of the present invention in that the mica sheet is arranged in such a way that it covers the outline of the opening from the housing side.

[0196] Hereinafter, the battery pack of the second embodiment of the present invention will be described in detail with reference to the accompanying drawings.

[0197] Figure 5A This is an enlarged cross-sectional view schematically showing an example of the cross-section of the heat-insulating material of the battery pack according to the second embodiment of the present invention.

[0198] Figure 5B This is an enlarged cross-sectional view schematically showing another example of the cross-section of the heat-insulating material of the battery pack according to the second embodiment of the present invention.

[0199] exist Figure 5A The heat insulation material 140a shown includes mica sheet 142 and mica sheet 150.

[0200] An opening 142a is formed in the mica sheet 142, and the mica sheet 150 is arranged to cover the outline of the opening 142a from the housing (not shown) side.

[0201] In addition, mica sheet 150 is bonded to the surface of mica sheet 142 by an adhesive (not shown).

[0202] exist Figure 5B The thermal insulation material 140b shown is different from the thermal insulation material 140a described above in that it is provided with a plurality of mica sheets 150.

[0203] If the mica sheet is configured in this way, there will be no gap between the mica sheet and the opening, which will easily prevent gas from flowing back between the mica sheet and the opening.

[0204] Apart from the differences described above, the preferred materials of each component of the battery pack in the second embodiment of the present invention are the same as the preferred materials described in the description of the battery pack in the first embodiment of the present invention.

[0205] (Third implementation method)

[0206] Next, the battery pack according to the third embodiment of the present invention will be described.

[0207] The battery pack of the third embodiment of the present invention differs from the invention of the first embodiment described above in that the heat insulation material further includes a second heat insulation sheet, which is laminated on the mica sheet in such a way that it covers the opening from the housing side.

[0208] Hereinafter, the battery pack of the third embodiment of the present invention will be described in detail with reference to the accompanying drawings.

[0209] Figure 6 This is an enlarged cross-sectional view schematically illustrating an example of a battery pack according to a third embodiment of the present invention.

[0210] Figure 6 The battery pack 210 shown includes: a module 220 having a plurality of battery cells 221 and a connection module component 220a connecting the battery cells 221; and a housing 230 for housing the module 220.

[0211] In the battery pack 210, a safety valve 222 is provided in each battery cell 221.

[0212] In addition, in the battery pack 210, a heat insulation material 240 is provided between the module 220 and the housing 230.

[0213] Furthermore, the battery pack 210 is configured such that the safety valve 222 is located on the upper side in the vertical direction. That is, with Figure 1B The battery pack 10 shown is configured upside down.

[0214] The thermal insulation material 240 consists of a mica sheet 242 and a second thermal insulation sheet 243, which are stacked sequentially from bottom to top.

[0215] An opening 242a is formed in the mica sheet 242, and a mica sheet 250 is disposed inside the opening 242a.

[0216] Mica sheet 250 is bonded to mica sheet 242 (inner wall of opening 242a) by an adhesive (not shown).

[0217] In addition, the second heat insulation sheet 243 is laminated on the mica sheet 242 in such a way that it covers the opening 242a from the side of the housing 230.

[0218] Next, the function of the second thermal insulation sheet 243 will be explained using the accompanying drawings.

[0219] Figures 7A to 7C The diagram illustrates the principle of preventing thermal runaway in the event of thermal runaway in a battery cell in the battery pack of the third embodiment of the present invention.

[0220] like Figure 7A As shown, when a battery cell 221a experiences thermal runaway and generates high-temperature gas from the battery cell 221a, gas G is discharged from safety valve 222a (in... Figure 7A In the diagram, the symbol "G" represents gas, and the arrow indicates the direction of gas flow.

[0221] Then, the gas released from safety valve 222a reaches the insulation material 240.

[0222] Gas G reaches the mica sheet 242, which is the insulation material 240.

[0223] An opening 242a is formed in the mica sheet 242, and when the mica sheet 242 is viewed from above, the opening 242a is located at a position that overlaps with the safety valve 222.

[0224] A mica sheet 250 is disposed inside the opening 242a of the mica sheet 242, and the mica sheet 250 is bonded to the mica sheet 242 by an adhesive (not shown).

[0225] The gas G reaching the vicinity of the opening 242a of the mica sheet 242 is at a high temperature, thus thermally decomposing the adhesive bonding the mica sheet 250. As a result, the adhesion between the mica sheet 250 and the mica sheet 242 weakens.

[0226] In addition, air pressure is applied to the mica sheet 250 from the module 220 side toward the housing 230 side.

[0227] The result, such as Figure 7B As shown, mica sheet 250 is peeled off from mica sheet 242.

[0228] Then, the gas G passes through the opening 242a of the mica sheet 242 and reaches the second insulation sheet 243.

[0229] Gas G is blocked by the second insulating sheet 243. In addition, the second insulating sheet 243 is pushed upward by gas G in a manner that allows it to leave the mica sheet 242.

[0230] As a result, it is possible to prevent gas G from coming into contact with the housing 230.

[0231] After that, as Figure 7CAs shown, gas G diffuses through the gap S formed between the second insulating sheet 243 and the mica sheet 242. Then, the temperature and pressure of gas G decrease.

[0232] The second heat insulation sheet 243 is as described above. Figure 7C As shown, the configuration can be arbitrary as long as the gas G can push upwards from the mica sheet 242 to form a gap S.

[0233] For example, the second insulation sheet 243 may be disposed on the mica sheet 242 without being fixed, or it may be disposed on the mica sheet 242 in a manner in which a portion of it is fixed.

[0234] The second heat insulation sheet 243 may also be composed of sheet components made primarily of magnesium silicate (containing approximately 75% to 85% magnesium silicate by weight) or sheet components made primarily of silicon dioxide.

[0235] (Other implementation methods)

[0236] In the description of the battery pack of the first embodiment of the present invention, when the mica sheet is viewed from above, an opening is located at a position that overlaps with a safety valve.

[0237] The battery pack of the present invention only requires that, when viewed from above, one opening of the mica sheet is located at a position that overlaps with at least a portion of a safety valve, or there may be a portion that does not overlap.

[0238] Furthermore, in the description of the battery pack of the first embodiment of the present invention, when the mica sheet is viewed from above, one opening is located at a position overlapping with a safety valve, but multiple openings may also be located at positions that overlap with at least a portion of a safety valve.

[0239] In the description of the first to third embodiments of the present invention above, the cases where the first heat-insulating sheet and the cover sheet are both mica sheets were described. However, in the battery pack of the present invention, the first heat-insulating sheet may also be a heat-resistant resin sheet. Additionally, the cover sheet may also be a heat-resistant resin sheet.

[0240] In addition, heat-resistant resin sheets can be made of polyamide resin, polybutylene terephthalate resin, or polypropylene resin.

[0241] The following matters are disclosed in this specification.

[0242] The present invention (1) is a battery pack comprising: a module having a plurality of battery cells each having a safety valve; a housing for housing the module; and a heat insulation material disposed between the module and the housing, characterized in that the heat insulation material comprises a first heat insulation sheet having a plurality of openings through the first heat insulation sheet, and a cover sheet covering at least a portion of the openings being disposed in each of the plurality of openings, the cover sheet being bonded to the first heat insulation sheet by an adhesive, and in a top-view perspective view of the first heat insulation sheet, one of the openings is located at a position overlapping at least a portion of one of the safety valves.

[0243] The present invention (2) is the battery pack of the present invention (1), wherein at least one of the cover sheets is disposed inside each of the plurality of openings.

[0244] The present invention (3) is the battery pack described in the present invention (2), wherein a plurality of the cover sheets are disposed inside each of the plurality of openings.

[0245] The present invention (4) is the battery pack described in the present invention (3), wherein at least a portion of the plurality of cover sheets are arranged in contact with each other, and the plurality of cover sheets are bonded to each other by an adhesive.

[0246] The present invention (5) is the battery pack described in the present invention (4), wherein, when the heat insulation material is viewed from the first heat insulation sheet side, the portions of the cover sheets that are in contact with each other are formed in a straight line.

[0247] The present invention (6) is a battery pack according to any one of the present inventions (1) to (5), wherein the cover sheet is configured such that at least a portion contacts the contour of the opening.

[0248] The present invention (7) is a battery pack according to any one of the present inventions (1) to (5), wherein the cover is configured to cover the opening from the housing side.

[0249] The present invention (8) is a battery pack according to any one of the present inventions (1) to (7), wherein the top view shape of the opening is selected from at least one shape selected from the group consisting of triangle, quadrilateral, hexagon, circle, ellipse and racetrack shape.

[0250] The present invention (9) is a battery pack according to any one of the present inventions (1) to (8), wherein the first heat insulation sheet is a mica sheet.

[0251] The present invention (10) is a battery pack according to any one of the present invention (1) to (8), wherein the first heat insulation sheet is a heat-resistant resin sheet.

[0252] The present invention (11) is a battery pack according to any one of the present inventions (1) to (10), wherein the cover sheet is made of the same material as the first heat insulation sheet.

[0253] The present invention (12) is a battery pack according to any one of the present inventions (1) to (11), wherein the adhesive comprises an organic adhesive.

[0254] The present invention (13) is a battery pack according to any one of the present inventions (1) to (12), wherein the heat insulation material further comprises a second heat insulation sheet, the second heat insulation sheet being laminated on the first heat insulation sheet such that it covers the opening from the housing side.

[0255] The present invention (14) is a battery pack according to any one of the present inventions (1) to (13), wherein the housing has a receiving portion consisting of a bottom and a side wall portion and a cover portion covering the receiving portion, and the safety valve is configured to be located on the bottom side or on the cover side.

[0256] Label Explanation

[0257] 10, 210: Battery pack; 20, 220: Module; 20a, 220a: Connecting module component; 20b: Busbar; 21, 21a, 221, 221a: Battery cell; 22, 22a, 222, 222a: Safety valve; 23: Terminal; 30, 230: Housing; 31: Storage section; 31b: Bottom; 31s: Side wall; 32: Cover; 40, 140a, 140b 240: Thermal insulation material; 42, 142, 242: Mica sheets; 42a, 142a, 242a: Openings; 50, 50a, 50b1, 50b2, 50b3, 50b4, 50c1, 50c2, 50d, 50e, 50f1, 50f2, 50f3, 50f4, 50f5, 50f6, 150, 250: Mica sheets; 243: Second thermal insulation sheet.

Claims

1. A battery pack, comprising: The module has multiple battery cells, each equipped with a safety valve; A housing that houses the module; and Thermal insulation material is disposed between the module and the housing. Its features are, The thermal insulation material includes a first thermal insulation sheet. The first heat insulation sheet has multiple openings that penetrate the first heat insulation sheet. Each of the plurality of openings is provided with a cover sheet that covers at least a portion of the opening. The cover sheet is bonded to the first heat insulation sheet with an adhesive. When the first insulation sheet is viewed from above, one of the openings is located at a position that overlaps with at least a portion of one of the safety valves.

2. The battery pack according to claim 1, wherein, At least one of the cover sheets is disposed on the inner side of each of the plurality of openings.

3. The battery pack according to claim 2, wherein, A plurality of cover plates are disposed on the inner side of each of the plurality of openings.

4. The battery pack according to claim 3, wherein, At least a portion of the plurality of said cover sheets are configured in contact with each other. The multiple cover sheets are bonded together with an adhesive.

5. The battery pack according to claim 4, wherein, When the insulation material is viewed from above from the side of the first insulation sheet, the portions of the cover sheets that are in contact with each other form a straight line.

6. The battery pack according to any one of claims 1 to 5, wherein, The cover is configured such that at least a portion of it contacts the contour of the opening.

7. The battery pack according to any one of claims 1 to 5, wherein, The cover is configured to cover the opening from the side of the housing.

8. The battery pack according to any one of claims 1 to 7, wherein, The top view shape of the opening is selected from at least one shape chosen from the group consisting of triangles, quadrilaterals, hexagons, circles, ellipses and racetracks.

9. The battery pack according to any one of claims 1 to 8, wherein, The first heat insulation sheet is a mica sheet.

10. The battery pack according to any one of claims 1 to 8, wherein, The first heat insulation sheet is a heat-resistant resin sheet.

11. The battery pack according to any one of claims 1 to 10, wherein, The cover sheet is made of the same material as the first heat insulation sheet.

12. The battery pack according to any one of claims 1 to 11, wherein, The adhesive includes organic adhesives.

13. The battery pack according to any one of claims 1 to 12, wherein, The insulation material further includes a second insulation sheet. The second heat insulation sheet is laminated onto the first heat insulation sheet in such a way that it covers the opening from the housing side.

14. The battery pack according to any one of claims 1 to 13, wherein, The housing has a storage section consisting of a bottom and side walls, and a cover section that covers the storage section. The safety valve is configured either on the bottom side or on the cover side.

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