Battery pack

Abstract

To provide a battery pack capable of suppressing deterioration of a case.SOLUTION: A battery pack according to the present disclosure includes a battery cell having a pressure release valve that discharges gas generated inside the cell, a heat-resistant material disposed to face the pressure release valve of the battery cell, and a case that houses the battery cell and the heat-resistant material and has a gap, wherein the heat-resistant material includes a gas flow path having a bent shape and formed from a region of one main surface on the battery cell side that faces the pressure release valve to a region of another main surface on the case side that faces the gap of the case.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] In non-aqueous electrolyte secondary batteries such as lithium-ion batteries, gas may be generated due to factors such as overcharging, which can cause an increase in pressure (internal pressure) inside the case housing the battery cells. To ensure safety against an increase in the internal pressure of the secondary battery, for example, the case of the secondary battery is provided with a pressure release valve. The pressure release valve opens a valve hole when the internal pressure of the secondary battery reaches a predetermined pressure or higher, releasing the gas inside the battery to the outside of the battery. This suppresses the increase in the internal pressure of the secondary battery. Alternatively, instead of a pressure release valve, the secondary battery may have a gap on the mating surface of the case housing the battery cells to release the gas inside the battery to the outside of the battery. However, since the gas generated inside the battery is hot, releasing the hot gas directly to the outside of the battery could cause deterioration of the gas release path and components outside the battery pack.

[0003] A solution to this problem is disclosed, for example, in Patent Document 1. The battery pack disclosed in Patent Document 1 prevents gases released from the battery cells from being forcefully ejected outside the case by sealing the gaps between the mating surfaces of the case with heat-resistant material. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2020 / 129596 Summary of the Invention [Problem to be solved by the invention]

[0005] In the battery pack of Patent Document 1, the gaps between the mating surfaces of the case are simply blocked with heat-resistant material, so if the high-temperature gas discharged from the gas exhaust valve of the battery cell directly hits areas other than the mating surfaces of the case that are not provided with heat-resistant material, there is a possibility that part of the case will deteriorate.

[0006] The present disclosure has been made to solve such problems, and has an object to provide a battery pack that can suppress deterioration of the case. [Means for solving the problem]

[0007] A battery pack according to the present disclosure includes a battery cell having a pressure release valve for releasing gas generated inside the cell, a heat-resistant material disposed opposite the pressure release valve of the battery cell, and a case containing the battery cell and the heat-resistant material and having a gap. The heat-resistant material has a meandering gas flow path extending from a region of one main surface facing the pressure release valve on the battery cell side to a region of the other main surface facing the case gap. The battery pack according to the present disclosure thereby releases gas released from the pressure release valve of each battery cell to the outside of the case through the meandering gas flow path provided in the heat-resistant material, thereby preventing the heat of the gas from directly hitting the inside of the case and thereby suppressing deterioration of the case due to the heat of the gas. Furthermore, the battery pack according to the present disclosure can reduce the temperature of the gas released to the outside of the case, thereby suppressing deterioration of devices outside the case due to the heat of the gas. [Effects of the Invention]

[0008] According to the present disclosure, it is possible to provide a battery pack that can suppress deterioration of the case. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram of a battery pack 1 according to a first embodiment. [Figure 2] FIG. 2 is a partially enlarged view of the battery pack 1 according to the first embodiment. [Figure 3] FIG. 3 is a partially enlarged view of the battery pack 1 according to the second embodiment. [Figure 4] FIG. 4 is a schematic diagram of a battery pack 1 according to the third embodiment. [Figure 5] FIG. 5 is a partial enlarged view of the mating surface between the upper cover 44 and the lower case 45 in the battery pack 1 according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Embodiment 1 Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. FIG. 1 is a schematic diagram of a battery pack 1 according to the first embodiment. The battery pack 1 includes a plurality of battery cells 2, a heat-resistant material 3, and a case 4. The battery pack 1 can be used as a power source for a vehicle drive motor. In the present disclosure, an example will be described in which the battery pack 1 houses a plurality of battery cells 2, but this is not limiting, and the battery pack 1 may house a single battery cell 2. Each component of the battery pack 1 will be described in detail below.

[0011] Each battery cell 2 is a secondary battery that can be charged and discharged. Each battery cell 2 is, for example, a lithium-ion battery or a nickel-metal hydride battery. Each battery cell 2 has, for example, a rectangular parallelepiped shape with a first horizontal direction (X-axis direction) as its short side and a second horizontal direction (Y-axis direction) perpendicular to the first direction as its long side. The multiple battery cells 2 are arranged side by side in the first direction (X-axis direction) inside the case 4. The multiple battery cells 2 are also electrically connected to each other. Each battery cell 2 is equipped with a pressure release valve 21.

[0012] The pressure release valve 21 is a safety valve for releasing flammable gas generated inside the battery cell 2 to the outside of the battery cell 2. For example, if the battery cell 2 is overcharged or has an internal short circuit, flammable gas may be generated from the electrolyte of the battery cell 2, causing the pressure inside the cell to increase. To ensure safety against an increase in the internal pressure of the battery cell 2, the pressure release valve 21 opens a valve hole and releases the flammable gas inside the battery cell 2 to the outside of the battery cell 2 when the pressure inside the battery cell 2 reaches or exceeds a predetermined pressure. This flammable gas is assumed to be at a temperature high enough to potentially deteriorate devices inside and outside the battery pack 1.

[0013] The pressure release valve 21 is arranged on the battery cell 2 so that the flammable gas is released in one direction. For example, the pressure release valve 21 may be arranged on the battery cell 2 so that the flammable gas is released in the second direction (Y-axis direction), or may be arranged on the battery cell 2 so that the flammable gas is released in a third direction (Z-axis direction), which is the vertical direction. In other words, the pressure release valve 21 may be arranged on the battery cell 2 so that no other battery cell 2 is located in the direction of the flammable gas release.

[0014] The heat-resistant material 3 is mainly made of a heat-resistant substance that can maintain its properties against the heat generated by the flammable gas released by the pressure release valve 21. The heat-resistant material 3 may also be made of a substance with low thermal conductivity. That is, the heat-resistant material 3 may be made of a heat-insulating material. Specifically, the heat-resistant material 3 is made of mica. However, the heat-resistant material 3 is not limited to mica, and may be a resin, a metal, or a ceramic.

[0015] Alternatively, the heat-resistant material 3 may be made of a substance having a heat dissipation property that can lower the temperature of the flammable gas when the flammable gas hits the heat-resistant material 3. In other words, the heat-resistant material 3 may be made of a substance with high thermal conductivity.

[0016] The heat-resistant material 3 is housed in the case 4 together with the multiple battery cells 2. Specifically, the heat-resistant material 3 is disposed in the space between the battery cells 2 and the case 4 within the case 4. The heat-resistant material 3 is disposed at least opposite the pressure release valve 21. In other words, the heat-resistant material 3 is disposed at least in the direction in which the pressure release valve 21 releases flammable gas. That is, the heat-resistant material 3 may be disposed only on the surface facing the second direction (Y-axis direction) or the third direction (Z-axis direction), or may be disposed over the entire space within the case 4. The heat-resistant material 3 may also be attached to the inside of the case 4.

[0017] The case 4 is a container that forms at least a part of the outer shell of the battery pack 1. That is, the case 4 may surround the entire battery pack 1, as shown in FIG. 1. The case 4 may also have a rectangular parallelepiped shape, but the shape of the case 4 is not limited to this and may have any shape as long as it can accommodate a plurality of battery cells 2 and heat-resistant material 3. For example, the case 4 is formed from an aluminum plate. However, the case 4 is not limited to an aluminum plate and may be formed from resin or a metal other than aluminum.

[0018] Next, the configurations of the heat-resistant material 3 and the case 4 according to the first embodiment will be described with reference to Fig. 2. Fig. 2 is a partially enlarged view of the battery pack 1 according to the first embodiment.

[0019] First, the configuration of the heat-resistant material 3 will be described. The heat-resistant material 3 has a meandering gap (gas flow path) 31. Here, the "meandering shape" is also referred to as a "labyrinth structure." The meandering gap 31 is formed from a region of one main surface of the heat-resistant material 3 facing the pressure release valve 21 on the battery cell 2 side, to a region of the other main surface of the heat-resistant material 3 facing the gap 41 in the case 4 on the case 4 side. In other words, the meandering gap 31 has a first opening (inlet) on one main surface of the heat-resistant material 3 to take in the flammable gas released from the pressure release valve 21, and a second opening (outlet) on the other main surface of the heat-resistant material 3 to release the flammable gas to the gap 41 in the case 4. In other words, the meandering gap 31 is a path for the flammable gas released from the pressure release valve 21. Specifically, the meandering gap 31 is a heat release path for the flammable gas released from the pressure release valve 21.

[0020] For example, the flammable gas reduces the gas heat by exchanging heat with the air in the path while passing through the meandering gap 31. Alternatively, if the heat-resistant material 3 is made of a heat-dissipating substance, the flammable gas reduces the gas heat by exchanging heat with the heat-resistant material 3 through the wall surface of the meandering gap 31.

[0021] Here, the first opening of the meandering gap 31 and the pressure release valve 21 may be arranged to be continuous with each other, or may be arranged with a gap therebetween. In other words, the flammable gas released from the pressure release valve 21 may be configured so that all of the flammable gas flows into the first opening, or so that only a portion of the flammable gas flows into the first opening. Similarly, the second opening of the meandering gap 31 and the gap 41 of the case 4 may be arranged to be continuous with each other, or may be arranged with a gap therebetween.

[0022] The meandering gap 31 has a distance equal to or greater than the thickness of the heat-resistant material 3, i.e., the thickness of the heat-resistant material 3 in the direction in which the pressure release valve 21 releases the flammable gas. The meandering gap 31 is formed so as to bend inside the heat-resistant material 3. Specifically, the meandering gap 31 may be formed in a crank shape as shown in FIG. 2. Alternatively, the meandering gap 31 may be formed in an S-shape, a Z-shape, or a wave shape.

[0023] For example, the bent gap 31 may have a first opening on the second direction (Y-axis direction) of the pressure release valve 21 arranged to release flammable gas in the second direction (Y-axis direction). Alternatively, the bent gap 31 may have a first opening on the third direction (Z-axis direction) of the pressure release valve 21 arranged to release flammable gas in the third direction (Z-axis direction). In other words, the bent gap 31 may have a first opening at a position on one main surface of the heat-resistant material 3 that is closest to the pressure release valve 21.

[0024] Similarly, the bent gap 31 may have a second opening on the axis of the gap 41 of the case 4. In other words, the bent gap 31 may have a second opening at a position on the other main surface of the heat-resistant material 3 where the distance to the gap 41 is shortest.

[0025] The heat-resistant material 3 can have the number of meander-shaped gaps 31 corresponding to the number of pressure release valves 21. That is, the heat-resistant material 3 may have the same number of pairs of first and second openings as the pressure release valves 21, or may have a number of pairs of first and second openings exceeding the number of pressure release valves 21. However, the meander-shaped gap 31 is not limited to being independent of other meander-shaped gaps 31 in the heat-resistant material 3. The meander-shaped gap 31 can be designed to merge with other meander-shaped gaps 31 in the heat-resistant material 3, or can be designed to branch into multiple meander-shaped gaps 31.

[0026] Next, a description will be given of the configuration of the case 4. The case 4 has a gap 41 and a pressure adjustment mechanism .

[0027] The gap 41 is a hole that connects the inside of the case of the battery pack 1 to the outside of the case. Specifically, the gap 41 functions as an outlet for the flammable gas that fills the inside of the battery pack 1. In the example of FIG. 2, the gap 41 is provided so as to penetrate from one main surface to the other main surface in the second direction (Y-axis direction). The gap 41 is also disposed so as to face at least the second opening of the heat-resistant material 3. In other words, the gap 41 functions as an outlet for discharging the flammable gas that has passed through the bent gap 31 to the outside of the battery pack 1.

[0028] Gap 41 may be formed so that, in the process of the flammable gas passing through gap 41 and being released to the outside of case 4, a portion of the flammable gas hits the periphery of gap 41. In other words, gap 41 may be capable of performing heat exchange with case 4 by the flammable gas hitting the periphery of gap 41, thereby reducing the temperature of the flammable gas. In this case, gap 41 functions as a heat dissipation path through which the flammable gas passes in the process of being released to the outside of battery pack 1.

[0029] The number of gaps 41 is, for example, the same as the number of second openings of the heat-resistant material 3, but is not limited to the same number as the number of second openings, and may be, for example, greater than the number of second openings.

[0030] Pressure adjustment mechanism 42 is a mechanism, typically a valve, for adjusting the pressure inside battery pack 1. Pressure adjustment mechanism 42 is disposed above gap 41 and closes gap 41. When the pressure inside battery pack 1 reaches or exceeds a predetermined pressure, pressure adjustment mechanism 42 opens a closing portion of pressure adjustment mechanism 42 and releases gas inside battery pack 1 to the outside, thereby reducing the pressure inside battery pack 1.

[0031] The pressure adjustment mechanism 42 may be substituted by the gap 41. In other words, if the pressure inside the battery pack 1 can be adjusted by the gap 41, the pressure adjustment mechanism 42 does not need to be provided in the case 4.

[0032] In this way, the battery pack 1 according to the first embodiment discharges the gas discharged from the pressure release valve 21 of each battery cell 2 to the outside of the case 4 through the bent gap 31 provided in the heat-resistant material 3, thereby preventing the heat of the gas from directly hitting the inside of the case 4 and suppressing deterioration of the case 4 due to the heat of the gas. Furthermore, the battery pack 1 according to the first embodiment can reduce the temperature of the gas discharged to the outside of the case 4, thereby suppressing deterioration of devices outside the case 4 due to the heat of the gas.

[0033] Furthermore, the high-temperature combustible gas that has flowed into the meandering gap 31 of the heat-resistant material 3 exchanges heat with the air in the path and the heat-resistant material 3 while passing through the meandering gap 31. This reduces the temperature of the combustible gas. In particular, the longer the heat dissipation path of the meandering gap 31, the greater the effect of reducing the gas temperature.

[0034] The flammable gas that passes through the bent gap 31 is released to the outside of the battery pack 1 through the gap 41 in the case 4 and the pressure adjustment mechanism 42, but some of the gas may remain inside the case 4. Even in such a case, the temperature of the flammable gas is reduced as it passes through the bent gap 31, so the battery pack 1 can suppress deterioration of the case 4 due to the gas. Furthermore, the battery pack 1 can suppress deterioration of devices around the battery pack 1 due to the flammable gas that is released to the outside of the battery pack 1 through the gap 41 and the pressure adjustment mechanism 42.

[0035] As a specific example, consider a case where a wiring harness routing area is provided inside the battery pack 1 in a direction different from the direction in which the pressure release valve 21 releases flammable gas. In the battery pack 1 according to the first embodiment, the flammable gas discharged from each battery cell 2 flows into the bent gap 31 of the heat-resistant material 3, so there is little possibility that the high-temperature gas will directly hit the wiring harness. In addition, because the temperature of the gas that has passed through the bent gap 31 is reduced, there is little possibility that the gas that has passed through the bent gap 31 will deteriorate the wiring harness.

[0036] Embodiment 2 Next, a battery pack 1 according to a second embodiment will be described. Unlike the battery pack 1 according to the first embodiment, the battery pack 1 according to the second embodiment has a bent gap 43 in the case 4. Hereinafter, the second embodiment will be described with reference to the drawings. Note that the configurations of the battery cells 2 and the heat-resistant material 3 are the same as those in Figs. 1 and 2, and therefore description thereof will be omitted.

[0037] 3 is a partially enlarged view of a battery pack 1 according to the second embodiment. The case 4 of the battery pack 1 has a bent gap 43 instead of the gap 41 in the first embodiment. The battery pack 1 according to the second embodiment also has a pressure adjustment mechanism 42 in the gap 43, similar to the first embodiment.

[0038] In the second embodiment, the case 4 is mainly formed of a heat-resistant material that can maintain its properties against heat generated by the flammable gas released by the pressure release valve 21 through the bent gap 31. Alternatively, the case 4 may be formed of a heat-dissipating material that can lower the temperature of the flammable gas when the flammable gas hits the case 4. For example, the case 4 may be formed of a material with high thermal conductivity. Specifically, the case 4 is formed of aluminum. However, the case 4 is not limited to aluminum and may be made of resin, a metal other than aluminum, or ceramic. Alternatively, the case 4 may be formed of a material with low thermal conductivity. That is, the case 4 may be formed of a heat insulating material. Other features of the case 4 are the same as those in the first embodiment, and therefore description thereof will be omitted.

[0039] The meandering gap 43 is formed from a region of the inner surface of the case 4 that faces the second opening of the meandering gap 31 formed in the heat-resistant material 3 to the outer surface of the case 4. In other words, the meandering gap 43 has a first opening on the inner surface of the case 4 so as to take in the flammable gas that has been released to the case 4 side through the meandering gap 31 in the heat-resistant material 3, and has a second opening on the outer surface of the case 4 so as to release the flammable gas to the outside of the battery pack 1. In other words, the meandering gap 43 is a heat dissipation path through which the flammable gas that has passed through the meandering gap 31 in the heat-resistant material 3 further passes in the process of being released to the outside of the battery pack 1.

[0040] Here, the second opening of meandering gap 31 and the first opening of meandering gap 43 may be arranged to be continuous with each other or may be arranged with an interval between them. In other words, the flammable gas discharged from the second opening of meandering gap 31 may be configured so that all of the flammable gas discharged from the second opening of meandering gap 43 flows into the first opening of meandering gap 43, or the flammable gas may be configured so that only a portion of the flammable gas flows into the first opening of meandering gap 43.

[0041] The meandering gap 43 has a distance equal to or greater than the thickness of the case 4, i.e., the thickness of the case 4 in the direction in which flammable gas is released from the meandering gap 31. The meandering gap 43 is formed so as to bend inside the case 4. Specifically, the meandering gap 43 may be formed in a crank shape as shown in Fig. 3. Alternatively, the meandering gap 43 may be formed in an S-shape, a Z-shape, or a wave shape.

[0042] For example, the bent gap 43 may have a first opening on the second direction (Y-axis direction) of the opening on the case 4 side of the bent gap 31, which is formed to release flammable gas in the second direction (Y-axis direction). Alternatively, the bent gap 43 may have a first opening on the third direction (Z-axis direction) of the opening on the case 4 side of the bent gap 31, which is formed to release flammable gas in the third direction (Z-axis direction). In other words, the bent gap 43 may have a first opening at a position on the inner surface of the case 4 that is closest to the second opening of the bent gap 31.

[0043] The case 4 may have a number of bent gaps 43 corresponding to the number of second openings of the bent gaps 31. That is, the case 4 may have the same number of pairs of first and second openings as the number of second openings of the bent gaps 31, or may have a number of pairs of first and second openings greater than the number of second openings of the bent gaps 31. However, the bent gaps 43 are not limited to being independent of other bent gaps 43 in the case 4. The bent gaps 43 may be designed to merge with other bent gaps 43 in the case 4, or may be designed to branch into multiple bent gaps 43. That is, the number of first and second openings of the bent gaps 43 is not limited to being the same as the number of pressure release valves 21, or the same as the number of openings of the bent gaps 31.

[0044] As in the first embodiment, the pressure adjustment mechanism 42 is a mechanism for adjusting the pressure inside the battery pack 1, and is typically a valve. The pressure adjustment mechanism 42 may be disposed at one end of the bent gap 43 on the outer side of the battery pack 1, as shown in FIG. 3 , or at one end of the bent gap 43 on the inner side of the battery pack 1. Alternatively, the pressure adjustment mechanism 42 may be disposed at any location inside the bent gap 43. The function of the pressure adjustment mechanism 42 is the same as in the first embodiment, and therefore a description thereof will be omitted. The bent gap 43 may be substituted for the pressure adjustment mechanism 42. In other words, as long as the pressure inside the battery pack 1 can be adjusted by the bent gap 43, the pressure adjustment mechanism 42 does not need to be provided in the case 4.

[0045] In this way, in the battery pack 1 according to the second embodiment, the flammable gas passes not only through the bent gaps 31 in the heat-resistant material 3 but also through the bent gaps in the case 4, thereby further reducing the temperature of the flammable gas released to the outside of the battery pack 1 through the pressure release valve 21. As a result, the battery pack 1 according to the second embodiment can further suppress deterioration of devices outside the case 4 due to the heat of the gas.

[0046] Embodiment 3 Next, a battery pack 1 according to a third embodiment will be described. In the battery pack 1 according to the third embodiment, the case 4 is composed of an upper cover 44 and a lower case 45. Hereinafter, the third embodiment will be described with reference to the drawings. Note that the description of the same configuration as in the first and second embodiments will be omitted as appropriate.

[0047] FIG. 4 is a schematic diagram of a battery pack 1 according to a third embodiment. The case 4 according to the third embodiment has an upper cover 44 and a lower case 45. The upper cover 44 constitutes at least the upper portion of the case 4, and the lower case 45 constitutes at least the lower portion of the case 4. The upper cover 44 and the lower case 45 have mating surfaces so that the case 4 can accommodate a plurality of battery cells 2 and heat-resistant materials 3. Here, the mating surfaces may be formed by bending the respective ends of the upper cover 44 and the lower case 45 at a right angle. Alternatively, the mating surfaces may be formed so that the respective ends of the upper cover 44 and the lower case 45 fit together. The mating surfaces of the upper cover 44 and the lower case 45 are fastened together using, for example, multiple bolts. The gap between these mating surfaces serves as a flow path for releasing gas inside the case 4 to the outside of the case 4.

[0048] The heat-resistant material 3 according to the third embodiment is provided at least between the pressure release valve 21 and the mating surface of the case 4.

[0049] 5 is a partial enlarged view of the mating surface between upper cover 44 and lower case 45 in battery pack 1 according to the third embodiment. The mating surfaces of upper cover 44 and lower case 45, which are fastened together with bolts or the like (not shown), do not completely adhere to each other, leaving a small gap 41. Gap 41 formed in this mating surface is used as a flow path for releasing gas inside case 4 to the outside of case 4, similar to gap 41 in the first embodiment.

[0050] As in the first embodiment, the bent gap 31 of the heat-resistant material 3 is formed from a region of one of the main surfaces on the battery cell 2 side that faces the pressure release valve 21 to a region of the other main surface on the case 4 side that faces the gap in the mating surface of the case 4. Therefore, when flammable gas is released from the pressure release valve 21, the gas flows into a first opening in the main surface of the bent gap 31 on the pressure release valve 21 side, passes through the bent gap 31, and is released from a second opening in the main surface on the case 4 side. The gas released from the second opening is then released to the outside of the battery pack 1 through the gap 41 in the mating surface.

[0051] Here, the second opening of the bent gap 31 and the gap 41 on the mating surface of the case 4 may be disposed so as to be continuous with each other, or may be disposed with an interval therebetween.

[0052] In this way, the battery pack 1 according to the third embodiment can achieve the same effect as the battery pack 1 according to the first embodiment by using the gap provided in the mating surface between the upper cover 44 and the lower case 45 as a gas flow path for releasing gas inside the case 4 to the outside of the case 4. Furthermore, the battery pack 1 according to the third embodiment does not need to provide a gas flow path such as a dedicated gas release valve in the case 4, thereby reducing costs.

[0053] The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, gap 41 at the mating surfaces of battery pack 1 according to the third embodiment is not limited to gaps formed when upper cover 44 and lower case 45 of case 4 are separated into upper and lower halves, but may be gaps formed when case 4 is separated into left and right halves. [Explanation of symbols]

[0054] 1 battery pack, 2 multiple battery cells, 3 heat-resistant material, 4 case, 21 pressure release valve, 31 bent gap, 41 gap, 42 pressure adjustment mechanism, 43 bent gap, 44 upper cover, 45 lower case

Claims

1. a battery cell having a pressure relief valve for discharging gas generated inside the cell; a heat-resistant material disposed opposite the pressure release valve of the battery cell; a case that houses the battery cell and the heat-resistant material and has a gap; A battery pack comprising: the heat-resistant material has a meandering gas flow path formed from a region of one of its main surfaces facing the battery cell that faces the pressure release valve to a region of the other of its main surfaces facing the case that faces the gap in the case, Battery pack.

2. the case has a meandering gap formed from a region of an inner surface thereof facing an outlet of the gas flow path formed on the other main surface of the heat-resistant material to an outer surface of the case, The battery pack according to claim 1 .

3. The case has an upper cover and a lower case, The gap in the case is provided at a mating surface between the upper cover and the lower case. The battery pack according to claim 1 .

4. the heat-resistant material has an inlet for the gas flow path at a position on one of its main surfaces facing the battery cell that is closest to the pressure release valve; The battery pack according to claim 1 or 2.

5. The gap of the case is provided with a pressure adjustment mechanism that opens a valve hole when a predetermined pressure is exceeded. The battery pack according to claim 1 or 2.

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