JP7694427B2 - Battery module and battery pack - Google Patents

Description

This case relates to a battery module in which multiple battery cells arranged side by side in the horizontal direction with a heat insulating member interposed therebetween are housed in a battery case, and a battery pack including the battery module.

Conventionally, for high-output, high-capacity batteries, such as those used to drive vehicles, battery modules made up of a combination of multiple single cells (battery cells) and battery packs equipped with such battery modules have been known. In such battery modules or battery packs, if one battery cell experiences thermal runaway (emission of smoke), there is a possibility that adjacent battery cells may also experience thermal runaway. For this reason, battery modules or battery packs are required to suppress a chain reaction of thermal runaway (multiple explosions) of adjacent battery cells when one battery cell experiences thermal runaway. For example, Patent Document 1 discloses a battery module (battery pack) that prevents or suppresses heat transfer and multiple explosions to adjacent battery cells by disposing a thermal runaway prevention sheet between adjacent battery cells.

JP 2018-206605 A

In the above-mentioned Patent Document 1, lateral heat transfer and consecutive explosions between adjacent battery cells can be prevented. However, there is room for improvement in preventing consecutive explosions through the space above the battery cells. The upper surface of each battery cell may be provided with a safety valve to release internal gas or smoke to lower the internal pressure when the internal pressure of the battery cell rises, for example, when the battery cell generates heat and emits smoke due to an internal short circuit or overcharging. This is because in a battery module or battery pack having such battery cells, gas released from the safety valve of some battery cells may be transferred to other battery cells through the space above the battery cells, causing consecutive explosions.

This invention was invented in consideration of the above problems, and one of its objectives is to prevent consecutive explosions of the other battery cells when gas is released from one of the multiple battery cells. However, this objective is not the only objective, and another objective of this invention is to achieve effects that cannot be obtained by conventional technology, which are derived from the configurations shown in the embodiments of the invention described below.

The disclosed battery module and battery pack can be realized as aspects or application examples disclosed below, and solve at least some of the above problems.
(1) The battery module disclosed herein is a battery module in which a plurality of battery cells arranged side by side in the horizontal direction with a heat insulating member interposed therebetween are housed in a battery case, and a safety valve is provided on the upper surface of each of the battery cells to open due to an increase in the internal pressure of the battery cell and release gas within the battery cell, and when the safety valve of any of the battery cells opens, a heat insulating film for preventing multiple explosions is formed on the upper surfaces of the other battery cells by the gas released from the battery cell with the safety valve open. The battery case includes a lid portion that covers the plurality of battery cells above the upper surfaces of the plurality of battery cells. A member constituting the heat insulating film is provided on the lid portion, and the heat insulating film is formed when the member falls onto the upper surfaces of the plurality of battery cells due to the released gas.

( 2 ) The member is preferably the lid, and the lid preferably includes a support portion that is provided at a position on the outer periphery of the battery case that does not overlap with a side wall portion of the battery case and supports the lid, and a smoke exhaust portion that is provided directly above the safety valve of each battery cell. In this case, it is preferable that the lid is dropped by the released gas in such a manner that the support portion is dissolved first, and the smoke exhaust portion directly above the battery cell whose safety valve is open is dissolved next to the support portion to form a smoke exhaust port that releases the released gas to the outside of the battery case, thereby forming the insulating film.

( 3 ) It is preferable that the support portion is formed of a resin having a lower melting point than the portion of the lid portion other than the support portion.
( 4 ) It is preferable that the support portion is formed thinner than the portion of the lid portion other than the support portion.

( 5 ) It is preferable that a surface of the lid portion facing the battery cell is provided with a plurality of packages each including a ceramic and a thermosetting resin in a film that is easily dissolved by the released gas. In this case, it is preferable that the members are the ceramic and the thermosetting resin.
( 6 ) It is preferable that the packaging body is positioned at a position offset from directly above the safety valve of each of the battery cells.
( 7 ) A battery pack disclosed herein includes a plurality of battery modules according to any one of (1) to ( 6 ) above.

The disclosed battery module and battery pack can prevent gas from being released from any one of multiple battery cells, causing a continuous explosion in the other battery cells.

FIG. 2 is a longitudinal sectional view of the battery module according to the first embodiment. FIG. 2 is a diagram for explaining the operation of the battery module of FIG. 1, and is a vertical cross-sectional view of the battery module showing a state in which a safety valve of one of the plurality of battery cells is open. FIG. 2 is a diagram for explaining the operation of the battery module of FIG. 1, and is a vertical cross-sectional view of the battery module showing a state in which a lid portion of a battery case that constitutes a heat insulating film has fallen. FIG. 11 is a vertical cross-sectional view of a battery module according to a second embodiment. FIG. 5 is a diagram for explaining the operation of the battery module of FIG. 4, and is a vertical cross-sectional view of the battery module showing a state in which a heat insulating film has been formed.

The battery module and battery pack as embodiments will be described with reference to the drawings. The embodiments described below are merely examples, and are not intended to exclude the application of various modifications or techniques not explicitly stated in the following embodiments. Each configuration of the present embodiment can be modified in various ways without departing from the spirit of the embodiment. In addition, the configurations can be selected or combined as necessary.

The battery module of the embodiment includes a plurality of battery cells, and the battery pack includes the battery module. The battery module has a function of preventing the other battery cells from exploding due to gas released from a battery cell (hereinafter also referred to as "released gas") when any of the battery cells generates heat and emits smoke due to, for example, an internal short circuit or overcharging. The upper surface of each battery cell is provided with a safety valve that opens when the internal pressure of the battery cell increases to release the gas in the battery cell. In the battery module, when the safety valve of any of the battery cells opens, a heat insulating film for preventing explosion is formed on the upper surface of the other battery cells other than the battery cell. This prevents the heat of the released gas from being transferred to the other battery cells through the space above the battery cell, thereby preventing explosion of the other battery cells.

Note that the phrase "An insulating film for preventing multiple explosions is formed on the upper surface of the other battery cells other than the battery cell in question" in the claims does not mean that no insulating film is formed on the upper surface of the "battery cell in question." The description means that an insulating film is formed on at least the "upper surface of the other battery cells." In other words, the configuration intended by the above description includes a configuration in which an insulating film is formed on part of the upper surface of the "battery cell in question," including the "upper surface of the other battery cells."

[1. First embodiment]
[1-1. Configuration]
FIG. 1 shows a battery module 1 as a first embodiment. Although not shown, the battery pack is configured by housing a plurality of battery modules 1 in a casing, and is mounted, for example, under the floor of a vehicle (not shown). The battery pack containing the plurality of battery modules 1 is used as a battery for driving the vehicle. This vehicle is a hybrid vehicle (HEV, Hybrid Electric Vehicle) or a plug-in hybrid vehicle (PHEV, Plug-in Hybrid Electric Vehicle) equipped with an engine and a motor as a driving source, a generator as a power generation device, and a battery (battery pack) as a power storage device, or an electric vehicle (BEV, Battery EV) equipped with a motor as a driving source and a battery as a power storage device. A plug-in hybrid vehicle means a hybrid vehicle capable of external charging of the battery or external power supply from the battery. A plug-in hybrid vehicle and an electric vehicle are provided with a charging port (inlet) for inserting a charging cable through which power is supplied from an external charging facility and an outlet (outlet) for external power supply.

As shown in FIG. 1, the battery module 1 is configured by housing a plurality of battery cells 2 arranged side by side in a horizontal direction with insulating members 4 interposed therebetween in a battery case 3 (hereinafter, simply referred to as "case 3"). In this embodiment, the member constituting the insulating film for preventing multiple explosions is the lid portion 6 of the case 3, which will be described later. In the battery module 1 of the first embodiment, when any one of the plurality of battery cells 2 generates heat and emits smoke, the lid portion 6 of the case 3 falls due to the gas released from that battery cell 2. As a result, the lid portion 6 functions as an insulating film for preventing multiple explosions, which prevents heat transfer between the space above the battery cell 2 and each battery cell 2.

Each battery cell 2 is, for example, a rectangular battery such as a lithium ion secondary battery, and includes a container portion 21 and an upper surface portion 22 (upper surface) that seals the container portion 21 from above. The container portion 21 is, for example, a pouch-type film made of aluminum foil coated with resin. The container portion 21 may be a bottomed cylindrical type made of metal such as stainless steel. Inside the container portion 21, an electrode body (electricity storage element) including a positive electrode plate, a negative electrode plate, and a separator is housed together with an electrolyte. Note that in Figs. 1 to 3 and Figs. 4 and 5 relating to a battery module 1' of a second embodiment described later, only the upper surface portions 22, 22' of the battery cells 2, 2' are shown as cross-sectional views, and other parts are shown in a simplified manner. Also, Figs. 1 to 5 show battery modules 1, 1' in which eight battery cells 2, 2' are arranged side by side in the horizontal direction (left and right direction in the figures) in the cases 3, 3', but the number of battery cells 2, 2' is not limited to this.

On the upper surface portion 22, a positive terminal 23 and a negative terminal 24 are provided to protrude upward and are connected to the positive and negative plates of the electrode body contained in the container portion 21, respectively. The battery cells 2 are connected in series to each other via the positive terminal 23 and the negative terminal 24, respectively. The upper surface portion 22 is further provided with a safety valve 25 between the positive terminal 23 and the negative terminal 24. The safety valve 25 is formed relatively weaker than other parts of the upper surface portion 22, and is configured to open when the internal pressure of the container portion 21 reaches a predetermined value, for example, when an internal short circuit occurs in the container portion 21. As a result, even if the internal pressure of the container portion 21 increases, the gas in the container portion 21 is ejected to the outside from the opened safety valve 25. Therefore, it is possible to suppress the rupture of the container portion 21 due to the increase in internal pressure.

The case 3 is the outer shell of the battery module 1, which is formed by combining the lid part 6 from above the tray part 5. The case 3 is formed of a metal such as stainless steel, for example, except for the support part 61 and the smoke exhaust part 62 described below.

The tray portion 5 is a box-shaped container with an open top. The tray portion 5 has a flat bottom wall portion 51 and a side wall portion 52 erected from the peripheral portion of the bottom wall portion 51. The bottom wall portion 51 has, for example, a substantially rectangular shape when viewed from above. The side wall portion 52 has a rectangular tubular shape corresponding to the shape of the bottom wall portion 51. The multiple battery cells 2 are placed on the bottom wall portion 51. Note that, although FIG. 1 illustrates multiple battery cells 2 arranged side by side in the left-right direction, the multiple battery cells 2 may also be arranged side by side in a direction perpendicular to the paper surface. In other words, the above-mentioned "horizontal direction" means a direction along the bottom wall portion 51 of the case 3.

The lid portion 6 is a member that covers all of the battery cells 2 above the battery cells 2. The lid portion 6 in this embodiment has a generally rectangular shape in top view corresponding to the shape of the tray portion 5 described above, and is a flat plate that fits inside the side wall portion 52 of the tray portion 5. In other words, the lid portion 6 in this embodiment is positioned so as not to overlap the side wall portion 52 in the lateral direction. The lid portion 6 is positioned above the top surface portions 22 of the battery cells 2 so as to form a space between the lid portion 6 and the top surface portions 22 of the battery cells 2.

The lid portion 6 is provided with a support portion 61 that is provided at a position that does not overlap laterally with the side wall portion 52 at the outer periphery that forms the outer shape of the lid portion 6 when viewed from above and supports the lid portion 6. As described above, since the lid portion 6 in this embodiment is fitted inside the side wall portion 52 of the tray portion 5, the support portion 61 forms the outer periphery of the lid portion 6 itself. The support portion 61 supports the lid portion 6 by being adhered to the inner surface of the side wall portion 52. The lid portion 6 is supported and fixed in position by the support portion 61, and the case 3 is sealed by adhering the support portion 61 to the inner surface of the side wall portion 52.

The support portion 61 is configured to be more easily melted by the released gas than the other portions of the lid portion 6. For example, the support portion 61 may be configured by molding only the portion constituting the support portion 61 of the lid portion 6 from a resin having a lower melting point than the other portions of the support portion 61. Alternatively, the support portion 61 may be configured by forming only the portion constituting the support portion 61 to be thinner than the other portions of the support portion 61. Alternatively, a combination of these may be used.

Furthermore, the lid portion 6 is provided with a smoke exhaust portion 62 directly above the safety valve 25 of each battery cell 2, which is configured to be the second most likely to melt by released gas after the support portion 61. The smoke exhaust portion 62 may be configured, for example, by molding a resin having a higher melting point than the support portion 61 and a lower melting point than the portions of the lid portion 6 other than the support portion 61 and the smoke exhaust portion 62. The smoke exhaust portion 62 may also be configured to be thicker than the support portion 61 and thinner than the portions of the lid portion 6 other than the support portion 61 and the smoke exhaust portion 62. Alternatively, the smoke exhaust portion 62 may be configured by combining these so as to be the second most likely to melt after the support portion 61.

The heat insulating member 4 is a member that suppresses the transfer of heat to adjacent battery cells 2. The heat insulating member 4 is formed, for example, from a ceramic material. In this embodiment, the heat insulating member 4 is illustrated as being erected from the bottom wall portion 51 of the case 3 to the position of the upper surface portion 22 of the battery cell 2. The shape of the heat insulating member 4 is not particularly limited as long as it is a shape that suppresses the transfer of heat between adjacent battery cells 2. In addition, a cooling path through which cooling water flows to cool each battery cell 2 may be provided between adjacent battery cells 2. In addition, a fan or a ventilation path for air-cooling each battery cell 2 may be provided inside the case 3.

[1-2. Effect]
Next, the operation of the battery module 1 when one of the battery cells 2 generates heat and emits smoke will be described.

For example, when one of the multiple battery cells 2 (hereinafter referred to as the "smoking cell 2") generates heat and emits smoke due to an internal short circuit or overcharging, as shown in FIG. 2, the internal pressure of the container 21 of the smoke-emitting cell 2 rises and the safety valve 25 opens. This causes high-temperature released gas to be ejected from the safety valve 25 of the smoke-emitting cell 2, filling the space between the battery cell 2 and the lid 6. The lid 6 is exposed to the high-temperature released gas, or the pressure of the released gas causes the support portion 61 of the lid 6, which is the most easily dissolved portion, to melt. This causes the support of the lid 6 by the support portion 61 to be released.

When the support by the support portion 61 is released, the lid portion 6 falls downward as shown in FIG. 3. As a result, the lid portion 6 becomes an insulating film that insulates the battery cell 2 from the space above it. At this time, the smoke exhaust portion 62 of the lid portion 6 located directly above the smoke-producing cell 2 is exposed to the high-temperature released gas ejected from the smoke-producing cell 2, or is dissolved by the pressure of the released gas. As a result, a smoke exhaust port 62h through which the released gas can flow is formed directly above the smoke-producing cell 2.

The gas released from the smoke-producing cell 2 is released from this smoke exhaust port 62h to the outside of the case 3. At this time, outside the case 3, the released gas also spreads above the battery cells 2 near the smoke-producing cell 2. However, as described above, the lid 6 exists as an insulating film between the other battery cells 2 other than the smoke-producing cell 2 and the space above them. Therefore, the lid 6 prevents the other battery cells 2 from generating heat due to the heat of the released gas.

In the battery module 1, not only is the heat insulating member 4 used to suppress lateral heat transfer between adjacent battery cells 2, but the lid 6, which acts as a heat insulating film, also suppresses heat transfer to other battery cells 2 through the space above the battery cell 2, thereby suppressing the explosion of other battery cells 2. As described above, the positive and negative terminals 23 and 24 protrude from the upper surface 22, so a small gap is formed between the upper surface 22 and the lid 6. However, since the released gas has the tendency to escape (flow) upward, it is difficult for the released gas to flow into this gap. The casing of the battery pack is preferably provided with a valve that opens when the internal pressure of the casing rises, and the released gas is preferably exhausted from the battery pack by opening this valve.

[1-3. Effects]
(1) According to the above-described battery module 1 and battery pack, when the safety valve 25 of the smoke-emitting cell 2 is opened, the gas released from the smoke-emitting cell 2 forms an insulating film for preventing multiple explosions on the upper surface of the upper surface portion 22 of the other battery cells 2. This prevents the heat of the released gas from being transferred to the other battery cells 2 through the space above the battery cell 2. This makes it possible to prevent multiple explosions of the other battery cells 2. In addition, in the battery module 1, the insulating film is formed only when the safety valve 25 is opened. In other words, during normal operation of each battery cell 2, the heat dissipation of each battery cell 2 is not hindered by the insulating film. This makes it possible to prevent a decrease in the heat dissipation performance of the battery cells 2. This in turn makes it possible to suppress deterioration of the battery cells 2 (the battery module 1 and the battery pack).

(2) The upper surface 22 of each battery cell 2 is provided with not only a safety valve 25 but also a positive terminal 23 and a negative terminal 24. For this reason, if the components constituting the insulating film are placed on the upper surface 22, the structure of the battery module or battery pack may become complicated. In contrast, in the battery module 1 and battery pack described above, the components constituting the insulating film are provided on the lid portion 6 of the case 3, so that the insulating film can be formed with a simple structure when smoke is generated without being restricted by the placement of the positive terminal 23 and negative terminal 24 of each battery cell 2.

(3) In the above-described battery module 1 and battery pack, the component that constitutes the insulating film is the lid portion 6 of the case 3. In this way, by using the lid portion 6 of the case 3 for housing each battery cell 2 as a component that constitutes the insulating film, it is possible to prevent the other battery cells 2 from exploding consecutively without increasing the number of parts. In addition, by using the lid portion 6 that covers the multiple battery cells 2 as a component that constitutes the insulating film, it is possible to reliably cover the top surfaces of the other battery cells 2, and it is possible to more reliably prevent the other battery cells 2 from exploding consecutively.

(4) If the support portion 61 is made of a resin with a lower melting point than the rest of the lid portion 6, the support portion 61 will begin to melt before the temperature rise in the space between the battery cell 2 and the lid portion 6 reaches the temperature at which that portion melts. This makes it possible to more reliably release the support of the lid portion 6 by the support portion 61 and drop the lid portion 6 using a simple technique. Also, in this case, the plate thickness of the support portion 61 can be made the same as the rest of the lid portion 6, so that the rigidity and strength of the lid portion 6 can be maintained while allowing the lid portion 6 to drop in the event of smoke generation.

(5) When the support portion 61 is formed thinner than the remaining portions of the lid portion 6, the lid portion 6 can be dropped using the heat and momentum (pressure) generated when smoking, with a simple configuration without changing the material of the lid portion 6. In addition, by combining the above-mentioned configuration methods for the support portion 61, the lid portion 6 can be dropped more quickly using the heat and momentum (pressure) generated when smoking.

[2. Second embodiment]
FIG. 4 is a vertical cross-sectional view showing a battery module 1' as a second embodiment. The battery module 1' differs from the battery module 1 of the first embodiment in that the material constituting the heat insulating film for preventing multiple explosions is different, and the case 3' does not have a support part 61 and a smoke exhaust part 62. In the following description, the configuration different from the first embodiment described above will be mainly described, and the configuration corresponding to the configuration of the first embodiment will be marked with a prime (') and the overlapping description will be omitted. Note that although the battery pack of the second embodiment is not shown, it is configured by housing a plurality of battery modules 1' in a casing, similar to the first embodiment.

In the battery module 1' of the second embodiment, the components constituting the heat insulating film for preventing multiple explosions are the ceramic 11 and thermosetting resin 12 provided on the lid 6' of the case 3'. In the battery module 1' and battery pack of the second embodiment, when some of the battery cells 2' generate heat and emit smoke, the ceramic 11 and thermosetting resin 12 are scattered and fall due to the released gas. Then, the thermosetting resin 12 hardens on the upper surface 22' of each battery cell 2' together with the ceramic 11 due to the heat of the released gas, forming a heat insulating film F (see FIG. 5) that prevents heat transfer between the space above each battery cell 2' and each battery cell 2'.

As shown in FIG. 4, the ceramic 11 and thermosetting resin 12 are arranged as a package 8 enclosed in a film 7 on the surface of the lid 6' facing the battery cell 2', i.e., on the underside. The ceramic 11 and thermosetting resin 12 are provided as a powder formed into fine particles and mixed together, for example, as shown enlarged by the two-dot chain line in FIG. 4. The particle size is, for example, a diameter smaller than 1 mm (for example, 400 μm). The film 7 is made of a thin material that is easily dissolved by the released gas.

A plurality of packaging bodies 8 containing the ceramic 11 and thermosetting resin 12 are provided. The packaging bodies 8 are preferably positioned at positions offset from directly above the safety valves 25' of each battery cell 2'. Here, seven packaging bodies 8 are illustrated as being positioned between adjacent battery cells 2', but the number of packaging bodies 8 is not limited to this. The arrangement of the packaging bodies 8 is also not limited to this. For example, the packaging bodies 8 may be positioned at positions offset in a direction perpendicular to the paper surface from the positions where the safety valves 25' of each battery cell 2' are provided.

The operation of the battery module 1' described above will now be explained. When the smoke-producing cell 2' produces smoke and the safety valve 25' of the smoke-producing cell 2' opens, high-temperature released gas is ejected from the safety valve 25' of the smoke-producing cell 2'. The film 7 of the multiple packages 8 attached to the lid 6' is melted by the heat of the released gas, exposing the ceramic 11 and thermosetting resin 12 powder. The ceramic 11 and thermosetting resin 12 are then scattered by the ejected released gas.

In more detail, the ceramic 11 and thermosetting resin 12 are blown away diagonally by the flow of released gas spreading from the safety valve 25' of the smoke generating cell 2' as shown by the dotted arrows in Figure 5. In this embodiment, as described above, the packaging body 8 is not placed directly above the smoke generating cell 2', so that the released gas flowing upward from the safety valve 25' of the smoke generating cell 2' prevents the ceramic 11 and thermosetting resin 12 from sticking to the lid 6'.

The scattered ceramic 11 and thermosetting resin 12 then fall onto the upper surface of the battery cell 2' and adhere thereto, where the heat and pressure of the released gas causes the thermosetting resin 12 to harden together with the ceramic 11. As a result, a heat insulating film F is formed on the upper surface 22' of the other battery cells 2'. Therefore, the heat insulating film F prevents heat transfer to the other battery cells 2' through the space above the battery cell 2', thereby preventing the other battery cells 2' from exploding in succession.

The above-mentioned battery module 1' and battery pack can achieve the same effect as the battery module 1 and battery pack of the first embodiment. That is, according to the above-mentioned battery module 1' and battery pack, when the safety valve 25' of the smoke-emitting cell 2' is opened, the gas released from the smoke-emitting cell 2' forms an insulating film F for preventing consecutive explosions on the upper surface of the upper surface portion 22' of the other battery cells 2', so that the consecutive explosions of the other battery cells 2' can be prevented. In addition, in the battery module 1' and battery pack, the insulating film F is formed only when the safety valve 25' is opened, so that the deterioration of the heat dissipation properties of the battery cells 2' can be prevented. Furthermore, since the ceramic 11 and thermosetting resin 12 constituting the insulating film F are provided on the lid portion 6', the insulating film F can be formed on the upper surface of each battery cell 2' with a simple structure.

(6) In addition, in the above-mentioned battery module 1' and battery pack, the components constituting the insulating film F are ceramic 11 and thermosetting resin 12, and the ceramic 11 and thermosetting resin 12 are placed on the underside of the lid portion 6' as a packaging body 8 enclosed in a film 7. In this way, consecutive explosions can be prevented simply by attaching the packaging body 8 to the underside of the lid portion 6', making it easy to apply to existing battery modules and battery packs and increasing versatility. In addition, since the battery module 1' is provided with multiple packaging bodies 8, it can respond to smoke generation from any of the multiple battery cells 2'.

(7) By positioning the packaging body 8 at a position offset from directly above the safety valve 25' of each battery cell 2', it is possible to prevent the ceramic 11 and thermosetting resin 12 contained in the packaging body 8 from sticking to the lid portion 6' due to the force of the released gas. In this case, the ceramic 11 and thermosetting resin 12 are blown away diagonally and fall along with the flow of released gas spreading from the safety valve 25' of the smoke-emitting cell 2'. This makes it possible to prevent the ceramic 11 and thermosetting resin 12 from collecting locally on the upper surface of the other battery cells 2'. As a result, it is possible to form an insulating film F evenly on the upper surface of the other battery cells 2'.

[3. Other]
The configurations of the battery modules 1, 1' and battery pack described above are examples. The battery pack does not have to include a plurality of the battery modules 1, 1' described above. In this case, each battery cell 2, 2' may be directly placed on a casing that forms the outer shell of the battery pack. In addition, in this case, the configuration of the case 3, 3' may be applied to the casing. In other words, the "battery module" in the claims is intended to mean (for convenience) "a battery case in which a plurality of battery cells arranged side by side in the horizontal direction via a heat insulating member are housed," and the "battery module" itself may be read as a "battery pack."

The battery cells 2, 2' are not limited to being rectangular, as long as they have safety valves 25, 25' on the upper surface portions 22, 22'. The shape of the case 3, 3' is not limited to being rectangular, as long as it can accommodate a plurality of battery cells 2, 2' arranged side by side in the horizontal direction. In the battery module 1 of the first embodiment, the lid portion 6 is not limited to the above-mentioned one, as long as the support portion 61 can melt and fall first when the battery cell 2 emits smoke. For example, the lid portion 6 may be fitted to the side wall portion 52 of the tray portion 5. In this case, the support portion 61 may be provided in the inner part of the outer periphery of the lid portion 6, at a position that does not overlap the side wall portion 52 in the horizontal direction (at a position where the inner part of the support portion 61 in the lid portion 6 falls when the support portion 61 melts).

The configuration of the lid portion 6 of the first embodiment may be applied to the battery module 1' of the second embodiment. In this case, the battery module 1' has a double insulating film formed by the insulating film F formed by the ceramic 11 and thermosetting resin 12 contained in the packaging body 8 and the insulating film formed by the lid portion 6', so that the insulating property of the insulating film is further improved. In particular, in the battery module 1' of the second embodiment, since the insulating film F is formed by the scattered ceramic 11 and thermosetting resin 12, it is difficult to accurately control the shape and position of the insulating film F. In contrast, in the battery module 1 of the first embodiment, since the insulating film is formed by the lid portion 6 that falls by its own weight, the shape and position of the insulating film can be more accurately controlled. Therefore, by applying the configuration disclosed in the first embodiment to the battery module 1' of the second embodiment, the insulating property of the insulating film can be further improved.

The lid 6' of the second embodiment may be provided with the smoke exhaust section 62 of the first embodiment. The lid 6' of the second embodiment may be provided with a smoke exhaust mechanism equipped with a hose that connects the inside of the case 3' to the outside of the case 3'. The battery modules 1, 1' are not limited to batteries for driving a vehicle, and may be applied to various battery modules and battery packs equipped with multiple battery cells.

1, 1' Battery module 2, 2' Battery cell 3, 3' Case (battery case)
Reference Signs 4, 4': Insulating member 6, 6': Lid 7: Film 8: Packaging body 11: Ceramic 12: Thermosetting resin 22, 22': Upper surface 25, 25': Safety valve 61: Support 62: Smoke exhaust 62h: Smoke exhaust port F: Insulating film

Claims (7)

In a battery module in which a plurality of battery cells are arranged in parallel in a horizontal direction with a heat insulating member interposed therebetween and housed in a battery case,
a safety valve is provided on an upper surface of each of the battery cells to open when the internal pressure of the battery cell increases to release gas within the battery cell;
When the safety valve of any one of the plurality of battery cells is opened, a heat insulating film for preventing multiple explosions is formed on the upper surfaces of the other battery cells by the gas released from the battery cell whose safety valve is opened ,
the battery case includes a lid portion that covers the plurality of battery cells above the upper surfaces of the plurality of battery cells,
The member constituting the heat insulating film is provided on the lid portion,
The released gas causes the member to fall onto the upper surfaces of the plurality of battery cells, thereby forming the insulating film.
A battery module comprising : The member is the lid portion,
the lid portion includes a support portion that is provided at a position on the outer periphery of the battery case that does not overlap with a side wall portion of the battery case and that supports the lid portion, and a smoke exhaust portion that is provided directly above the safety valve of each of the battery cells,
2. The battery module of claim 1, characterized in that the lid portion forms the insulating film by causing the support portion to dissolve first due to the released gas, and then causing the smoke exhaust portion directly above the battery cell where the safety valve is open to dissolve next to the support portion, thereby forming a smoke exhaust port that releases the released gas outside the battery case . 3. The battery module according to claim 2 , wherein the support portion is made of a resin having a melting point lower than that of the other portion of the lid portion than the support portion. 4. The battery module according to claim 2 , wherein the support portion is formed to be thinner than a portion of the lid portion other than the support portion. a surface of the lid portion facing the battery cell is provided with a plurality of packages each including a ceramic and a thermosetting resin in a film that is easily dissolved by the released gas;
The battery module according to claim 1 , wherein the member is the ceramic and the thermosetting resin. 6. The battery module according to claim 5 , wherein the packaging body is disposed at a position offset from directly above the safety valve of each of the battery cells. A battery pack comprising a plurality of battery modules according to any one of claims 1 to 6 .

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