Battery modules and battery packs

Abstract

To prevent continuous explosion to other battery cell when thermal runaway occurs in one battery cell in a battery module.SOLUTION: In a battery module 1, a plurality of battery cells 2 are housed side by side in a battery case 7. Each battery cell 2 has a safety valve for discharging a gas in the battery cell 2 by opening a valve by increase in inner pressure on each upper surface 2a. The battery case 7 includes a case body 8 that has an upper opening and houses a plurality of battery cells 2, and a lid 9 that is attached to the case body 8 and closes the upper opening. The lid 9 includes: a lid body 10 covering an upper portion of the plurality of battery cells 2; a support unit 11 that supports the lid body 10 relative to the case body 8 and being dissolved by a gas discharged when the safety valve of any of the battery cells 2 is opened; and a conductive member 12 that is mounted on a lower surface 10b of the lid body 10 and externally short-circuits the plurality of battery cells 2 when the support unit 11 dissolves and the lid body 10 falls.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a battery module in which a plurality of battery cells are housed side by side in a battery case, and a battery pack including the battery module. [Background technology]

[0002] Conventionally, high-power, high-capacity batteries, such as those used to drive vehicles, have employed battery modules consisting of a combination of multiple cells (battery cells), or battery packs equipped with such battery modules. In such battery modules or battery packs, if one battery cell experiences thermal runaway (emission of smoke), adjacent battery cells may also experience thermal runaway. For this reason, battery modules or battery packs are required to prevent a chain reaction of thermal runaway (chain heating, or so-called multi-explosion) in the event of thermal runaway in one battery cell. For example, Patent Document 1 discloses a battery module (battery pack) that prevents or suppresses heat transfer and multi-explosion between adjacent battery cells by disposing a thermal runaway prevention sheet between the adjacent battery cells. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-206605 Summary of the Invention [Problem to be solved by the invention]

[0004] However, even if a thermal runaway prevention sheet like that in Patent Document 1 is provided, depending on the degree of thermal runaway, there is a possibility that chain heating will occur due to heat transfer to adjacent battery cells. For this reason, there is room for improvement in the structure to prevent chain explosions when thermal runaway occurs.

[0005] The present invention was conceived in consideration of the above-mentioned problems, and one of its objectives is to prevent a series of explosions of other battery cells in a battery module when one battery cell experiences thermal runaway. However, other objectives of the present invention are not limited to this objective, but also to achieve effects that cannot be obtained by conventional techniques, which are derived from the configurations shown in the detailed description of the invention described below. [Means for solving the problem]

[0006] The disclosed battery module and battery pack can be realized as the following disclosed embodiments (application examples), which solve at least part of the above-mentioned problems. Each of the embodiments from embodiment 2 onwards is an embodiment that can be selected as an additional option, and each of the embodiments can be omitted. None of the embodiments from embodiment 2 onwards discloses an embodiment or configuration that is essential to the present invention.

[0007] Aspect 1. The disclosed battery module is a battery module in which multiple battery cells are housed side by side in a battery case, each of the battery cells having a safety valve on its upper surface that opens when internal pressure increases to release gas within the battery cell, the battery case including a case body having an upper opening and housing the multiple battery cells, and a lid attached to the case body to close the upper opening. The lid includes a lid body that covers the upper part of the multiple battery cells, a support part that supports the lid body relative to the case body and dissolves when gas is released when the safety valve of any of the battery cells opens, and an electrically conductive member attached to the underside of the lid body that dissolves the support part to externally short-circuit the multiple battery cells when the lid body falls.

[0008] Aspect 2. In the above aspect 1, it is preferable that two adjacent battery cells are externally short-circuited by one of the current-carrying members. Aspect 3. In the above aspect 1, it is preferable that one of the battery cells is externally short-circuited by one of the current-carrying members. Aspect 4. In any of the above aspects 1 to 3, the lid preferably has a resistor attached to the current-carrying member so as to be electrically conductive. Aspect 5. The disclosed battery pack includes a plurality of battery modules according to any one of aspects 1 to 4 above. [Effects of the Invention]

[0009] According to the disclosed battery module and battery pack, if one battery cell in the battery module experiences thermal runaway, the lid of the battery case falls and the current-carrying member causes an external short circuit between the battery cells, thereby reducing the energy contained in the battery cells. This reduces the force of the thermal runaway, and even if heat is transferred from the thermally runaway battery cell to an adjacent battery cell, it prevents the adjacent battery cell from experiencing thermal runaway and therefore prevents subsequent explosions of the other battery cells. [Brief explanation of the drawings]

[0010] [Figure 1] 2A and 2B are longitudinal cross-sectional views of a battery module according to a first embodiment (a cross-sectional view taken along the line A'-A' in FIG. 2A and a cross-sectional view taken along the line B'-B' in FIG. 2B). [Figure 2] 2(a) is a cross-sectional view of the battery module of FIG. 1 taken along the line AA, and FIG. 2(b) is a cross-sectional view of the battery module of FIG. 1 taken along the line BB. [Figure 3] 3A and 3B are diagrams for explaining the operation of the battery module of FIG. 1, in which (a) is a vertical cross-sectional view similar to FIG. 1, and (b) is a cross-sectional view taken along the arrow CC in FIG. 3A, with the lid body omitted. [Figure 4] 4A and 4B are cross-sectional views showing a battery module according to a second embodiment, where (a) is a longitudinal cross-sectional view (a cross-sectional view taken along the arrows D'-D' in FIG. 4B), and (b) is a cross-sectional view taken along the arrows DD in FIG. 4A. [Figure 5] 5A and 5B are diagrams for explaining the operation of the battery module of FIG. 4, in which (a) is a longitudinal cross-sectional view similar to FIG. 4A, and (b) is a cross-sectional view taken along the arrow EE in FIG. 5A, with the lid body omitted. [Figure 6] 5(a) to 5(c) are diagrams for explaining a modified example of the battery module of FIG. 4, showing a state in which a current-carrying member is placed on the top surface of the battery cell. [Figure 7]5A and 5B are diagrams illustrating another modified example of the battery module of FIG. 4, in which (a) is a plan view showing a state in which a current-carrying member is superimposed on the upper surface of a battery cell, and (b) is a side view thereof. [Figure 8] FIG. 10 is a diagram for explaining a modified example of the battery module of the first embodiment, showing a state in which current-carrying members overlap the top surfaces of two adjacent battery cells. DETAILED DESCRIPTION OF THE INVENTION

[0011] A battery module and a battery pack will be described as embodiments with reference to the drawings. The embodiments described below are merely examples, and are not intended to exclude various modifications or applications of techniques not explicitly described in the following embodiments. The configurations of the present embodiments can be modified in various ways without departing from the spirit of the embodiments. Furthermore, they can be selected or combined as needed.

[0012] The battery module of the embodiment includes a plurality of battery cells housed in a battery case, and the battery pack includes the battery module. When one of the plurality of battery cells generates heat and emits smoke due to, for example, an internal short circuit or overcharging, the battery module has a function of preventing the other battery cells from exploding consecutively due to gas released from the battery cell (hereinafter also referred to as "released gas").

[0013] The top surface of each battery cell is provided with a safety valve that opens when the internal pressure of the battery cell increases, releasing gas within the battery cell. When a battery cell generates heat and emits smoke due to an internal short circuit or overcharging, the safety valve opens to release the gas. Hereinafter, such a battery cell will be referred to as a "smoking cell." The battery module is structured so that the gas released from the smoking cell causes the lid body (lid body) that covers the upper opening of the battery case to fall. The battery module further has an electrically conductive member attached to the underside of the lid body, and is configured so that the lid body falling causes an external short circuit between the multiple battery cells.

[0014] An external short circuit releases (discharges) the energy of multiple battery cells, including the smoking cell, reducing the energy of each battery cell. The greater the energy of a battery cell, the more severe the thermal runaway becomes, and conversely, the lower the energy, the less severe the thermal runaway becomes (or multiple explosions do not occur). Therefore, by reducing the energy of each battery cell through an external short circuit, the force of the thermal runaway is suppressed regardless of the degree of thermal runaway, and multiple explosions of adjacent battery cells are prevented.

[0015] The following embodiments will show two examples of the above-described structure of a battery module. In the first embodiment, two adjacent battery cells are externally short-circuited by a single current-carrying member, and in the second embodiment, one battery cell is externally short-circuited by a single current-carrying member. These embodiments differ only in the external short-circuiting structure, and the other battery module structures (battery cells, battery case, etc.) are the same.

[0016] Although not shown, the battery pack is configured by housing multiple battery modules (described later) in a pack case. The battery pack is used, for example, as a vehicle drive battery and is mounted under the vehicle floor (not shown). This vehicle is a hybrid vehicle (HEV, Hybrid Electric Vehicle) equipped with an engine and motor as a drive source, a generator as a power generation device, and a battery (battery pack) as a power storage device, or a plug-in hybrid vehicle (PHEV, Plug-in Hybrid Electric Vehicle), or an electric vehicle (BEV, Battery EV) equipped with a motor as a drive source and a battery as a power storage device. A plug-in hybrid vehicle is a hybrid vehicle that can externally charge the battery or externally receive power from the battery. Plug-in hybrid vehicles and electric vehicles are provided with a charging port (inlet) for inserting a charging cable to supply power from an external charging facility and an outlet (outlet) for external power supply.

[0017] [1. First embodiment] [1-1.Configuration] 1, 2(a), and 2(b) are cross-sectional views showing a battery module 1 according to a first embodiment. FIG. 2(a) is a cross-sectional view taken along the line AA in FIG. 1, and FIG. 2(b) is a cross-sectional view taken along the line BB in FIG. 1. Note that the cross-sectional lines (A'-A' and B'-B') in FIG. 1 are shown in FIGS. 2(a) and 2(b). In FIG. 1, the cross-sectional view of the battery cell 2 is simplified, and in FIG. 2(b), the battery cell 2 and electrode terminal 3 are shown with a two-dot chain line and a dotted pattern to explain their positional relationship, which will be described later.

[0018] As shown in Figures 1 and 2(a), a battery module 1 is configured by accommodating a plurality of battery cells 2 arranged side by side in a battery case 7. Here, eight battery cells 2 are shown arranged side by side in the horizontal direction (left and right direction in the figure) with heat insulating members 5 in between, but the arrangement and number of battery cells 2 are not limited to this. The heat insulating members 5 are members that suppress the transfer of heat to adjacent battery cells 2, and are formed from, for example, a ceramic material. Note that instead of the heat insulating members 5, cooling passages through which a refrigerant (gas or liquid) flows between adjacent battery cells 2 may be provided to prevent heat transfer between adjacent battery cells 2.

[0019] All of the multiple battery cells 2 have the same configuration. In the following explanation, unless otherwise specified, the configuration of one battery cell 2 will be described. Also, in the drawings, only some of the components having the same configuration will be assigned the same reference numerals.

[0020] The battery cell 2 is, for example, a prismatic battery such as a lithium-ion secondary battery. The case (cell case) that forms the outer shell of the battery cell 2 may be, for example, a pouch-type film made of aluminum foil coated with resin, or a bottomed cylinder made of metal such as stainless steel. Inside the cell case, an electrode assembly (electricity storage element) including a positive electrode plate, a negative electrode plate, and a separator (none of which are shown) is housed together with an electrolyte.

[0021] A positive electrode terminal 3P and a negative electrode terminal 3N protrude from the top surface 2a of the battery cell 2 and are connected to the positive and negative electrode plates, respectively, of the electrode assembly housed in the cell case. The positive electrode terminal 3P and the negative electrode terminal 3N are spaced apart in the longitudinal direction (the vertical direction in FIG. 2(a)) of the top surface 2a of the battery cell 2. Hereinafter, a battery cell 2 is illustrated in which the positive electrode terminal 3P and the negative electrode terminal 3N are both located approximately in the center of the short side (the horizontal direction in the figure) of the top surface 2a of the battery cell 2. Hereinafter, when there is no need to distinguish between the positive electrode terminal 3P and the negative electrode terminal 3N, they will simply be referred to as "electrode terminals 3."

[0022] The multiple battery cells 2 are connected in series with one another via their positive electrode terminals 3P and negative electrode terminals 3N. Specifically, the orientations of the battery cells 2 are alternated so that the positive electrode terminals 3P and negative electrode terminals 3N of adjacent battery cells 2 are adjacent to each other. Among adjacent battery cells 2, the positive electrode terminal 3P of one battery cell 2 and the negative electrode terminal 3N of the other battery cell 2 are electrically connected by a bus bar 6. Note that seven bus bars 6 are provided to connect eight battery cells 2 in series.

[0023] A safety valve 4 is provided on the top surface 2a of the battery cell 2. The safety valve 4 opens when the internal pressure (pressure inside the cell case) increases, releasing gas from the battery cell 2. The safety valve 4 needs to be located at a position that does not interfere with at least the electrode terminals 3. In the illustrated example, the safety valve 4 is located approximately in the center of the longitudinal direction (between the two electrode terminals 3) and approximately in the center of the lateral direction. The safety valve 4 is made relatively weaker than other parts of the top surface 2a and is configured to open when the internal pressure of the cell case reaches a predetermined value, for example, in the event of an internal short circuit within the battery cell 2. As a result, even if the internal pressure of the battery cell 2 increases, the gas in the battery cell 2 is released to the outside from the open safety valve 4, thereby preventing the cell case from bursting due to increased internal pressure.

[0024] The battery case 7 includes a case body 8 that houses multiple battery cells 2, and a lid 9 that is attached to the case body 8. The battery case 7 is the outer shell of the battery module 1, configured by combining the lid 9 from above the case body 8, and is molded, for example, from metal such as stainless steel or resin, except for a support section 11 and a smoke exhaust section 13, which will be described later. The case body 8 is a box-shaped body with a bottom and an opening at the top, and is, for example, a rectangular parallelepiped shape with a rectangular opening.

[0025] The lid 9 is a member attached to the case body 8 to close its upper opening, and is positioned above and spaced apart from the battery cells 2, forming a space between the lid 9 and the battery cells 2. The outer shape of the lid 9 corresponds to the shape of the opening of the case body 8 (for example, a rectangular plate). As shown in FIG. 3(a), the lid 9 is designed to fall if the safety valve 4 of any battery cell 2 (the above-mentioned "smoking cell") opens and gas is released.

[0026] Specifically, as shown in Figures 1 and 2(b), the lid 9 has a lid main body 10 that covers the upper parts of the multiple battery cells 2 arranged inside the case main body 8, and a support part 11 that supports the lid main body 10 relative to the case main body 8. The lid main body 10 is formed in an outer shape (a rectangular shape that is one size smaller) that is slightly smaller than the opening of the case main body 8, and is not located above the side parts (parts other than the bottom) that make up the case main body 8. More specifically, as shown in Figure 1, the lid main body 10 is placed inside the opening of the case main body 8 so that the top surface of the lid main body 10 is approximately flush with the upper end surface of the case main body 8.

[0027] The support portion 11 is provided around the entire outer periphery of the lid body 10 and is adhesively fixed to the inner circumferential surface at the top end of the case body 8. This seals the battery case 7. Furthermore, the support portion 11 is a portion that dissolves due to gas released when the safety valve 4 of one of the battery cells 2 opens. When the support portion 11 dissolves, it loses its function of supporting the lid body 10, and as shown in FIG. 3(a), the lid body 10 falls downward (into the case body 8) and overlaps the battery cell 2.

[0028] The support part 11 is configured to be more easily dissolved by the released gas than the lid body 10. Methods for configuring the support part 11 include mainly changing the material and changing the shape. For example, the material of the support part 11 can be made to be more easily dissolved than the material of the lid body 10 (for example, a resin with a low melting point). Other examples include making the thickness (vertical dimension) of the support part 11 smaller than the thickness of the lid body 10, or making the support part 11 hollow. Furthermore, changing the material and changing the shape may be combined.

[0029] In addition to the above-described structure for allowing the lid 9 to fall, the battery module 1 also has a current-carrying member 12 that externally short-circuits the multiple battery cells 2 when the lid body 10 falls. The current-carrying member 12 is attached in advance to the underside 10b of the lid body 10, as shown in Figures 1 and 2(b). When the support portion 11 dissolves and the lid body 10 falls, the current-carrying member 12 falls together with the lid body 10 (as a unit) and comes into contact with the electrode terminals 3 of the battery cells 2, as shown in Figure 3(a).

[0030] In the battery module 1 of this embodiment, two adjacent battery cells 2 are externally short-circuited by one current-carrying member 12. In other words, the number of current-carrying members 12 is half the number of battery cells 2. Since the battery module 1 of this embodiment has eight battery cells 2, four current-carrying members 12 are provided. Note that if the number of battery cells 2 is an even number, the number of current-carrying members 12 is half that number. On the other hand, if the number of battery cells 2 is an odd number, externally short-circuiting two battery cells 2 at a time will leave one battery cell 2 remaining, and this remaining battery cell 2 can be externally short-circuited using the method of the second embodiment described below. Therefore, the number of current-carrying members 12 in this case is the number of battery cells 2 divided by two and rounded up.

[0031] As shown in Figures 2(b) and 3(b), the conductive member 12 is positioned so that when the lid body 10 falls, it electrically connects the positive electrode terminal 3P of one of the adjacent battery cells 2 to the negative electrode terminal 3N of the other battery cell 2. Note that Figure 3(b) is a cross-sectional view taken along the arrow CC in Figure 3(a) and does not show the lid body 10. The safety valve 4 with a dotted pattern in Figure 3(b) indicates that it is open due to released gas.

[0032] In this embodiment, the current-carrying member 12 is a rectangular plate that spans the positive electrode terminal 3P of one battery cell 2 and the negative electrode terminal 3N of the other battery cell 2. Furthermore, since the electrode terminals 3 of the multiple battery cells 2 are arranged in parallel in the longitudinal direction near both ends of the lateral direction of the case body 8, the current-carrying member 12 is arranged along the longitudinal direction at a position near one end of the lateral direction on the underside 10b of the lid body 10. Adjacent current-carrying members 12 in the longitudinal direction are arranged spaced apart from each other.

[0033] The current-carrying member 12 is made of a conductive material. Examples of conductive materials include metals (bus bars) such as copper, and conductive plastics. Depending on the material of the current-carrying member 12, there is a possibility that a severe short circuit (discharge) may occur in the event of an external short circuit. To prevent this, the cover 9 may have a resistor 14 (see FIG. 8, described later) electrically connected to the current-carrying member 12. By attaching the resistor 14 to the current-carrying member 12 and increasing the resistance value of the current-carrying member 12 with the resistor 14, a severe discharge can be prevented in the event of an external short circuit.

[0034] Methods for attaching current-carrying member 12 to underside 10b include, for example, fastening with bolts or screws, physically locking current-carrying member 12 by providing a recess in underside 10b with a claw or clip, or gluing. Any method will do as long as it prevents current-carrying member 12 from coming off underside 10b of lid body 10 when gas is released from smoke generating cell 2 or when lid body 10 is dropped.

[0035] Lid body 10 is provided with smoke exhaust section 13, which exhausts gas to the outside when it is released from smoke-producing cell 2 to prevent the gas from accumulating inside battery case 7. Smoke exhaust section 13 has smoke exhaust port 13h, which is an opening for exhausting gas. Smoke exhaust port 13h is normally closed when thermal runaway is not occurring, and is configured to be the next most easily dissolved by the released gas after support section 11 when gas is released from smoke-producing cell 2. In other words, when gas is released from smoke-producing cell 2, smoke exhaust section 13 dissolves next to support section 11, and exhausts the gas from smoke exhaust port 13h.

[0036] The smoke exhaust section 13 is disposed, for example, on the lid body 10, approximately directly above the safety valve 4 of each battery cell 2. As with the support section 11 described above, methods for configuring the smoke exhaust section 13 include mainly changing the material and the shape. For example, the smoke exhaust section 13 may be configured by molding it with a resin having a higher melting point than the support section 11 but a lower melting point than the lid body 10. The smoke exhaust section 13 may also be configured by forming it thicker than the support section 11 but thinner than the lid body 10. Alternatively, it may be configured by a combination of these methods.

[0037] [1-2. Actions and Effects] 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, if one of the battery cells 2 generates heat and smokes due to an internal short circuit or overcharging, the internal pressure of that battery cell 2 (the smoking cell) increases, the safety valve 4 opens, and high-temperature released gas is ejected. This released gas fills the space between the battery cell 2 and the lid 9. When the lid 9 is exposed to the high-temperature released gas or due to the pressure of the released gas, the support portion 11, which is most easily dissolved, melts. As a result, the support portion 11 loses its function of supporting the lid body 10.

[0038] As the support function of the support portion 11 is lost, the lid body 10 falls, as shown in Fig. 3(a). As a result, as also shown in Fig. 3(b), the current-carrying member 12 attached to the underside 10b of the lid body 10 comes into contact with the electrode terminals 3 of the battery cells 2, causing an external short circuit in multiple battery cells 2. The released gas is discharged to the outside through gaps on the outer periphery of the lid body 10 and the smoke exhaust portion 13.

[0039] Thus, with the battery module 1 and the battery pack including the battery module 1, if one battery cell 2 experiences thermal runaway, the released gas melts the support part 11, causing the lid body 10 of the battery case 2 to fall, and the current-carrying member 12 to externally short-circuit the multiple battery cells 2. Thermal runaway in a battery cell 2 becomes more severe the greater the energy of that battery cell 2. However, by short-circuiting, the energy of each battery cell 2 can be reduced, thereby suppressing the momentum of thermal runaway. In addition, even if heat is transferred from a thermally runaway battery cell 2 to an adjacent battery cell 2, the energy of the adjacent battery cell 2 is reduced, preventing thermal runaway in the adjacent battery cell 2. Therefore, if one battery cell 2 in the battery module 1 experiences thermal runaway, it is possible to prevent subsequent explosions of the other battery cells 2.

[0040] Furthermore, because two adjacent battery cells 2 are externally short-circuited by a single current-carrying member 12, the number of current-carrying members 12 can be reduced to approximately half the number of battery cells 2. This reduces both cost and weight increases. Furthermore, because the number of components placed inside the battery case 7 is reduced, heat is less likely to build up inside the battery case 7, improving structural safety and providing advantages even during normal use when thermal runaway is not occurring. Additionally, because the electrode terminals 3 of the battery cells 2 are usually located near the longitudinal ends of the battery cells 2, the current-carrying member 12 is also similarly located near the ends, preventing interference between the current-carrying member 12 and the safety valve 4.

[0041] In the above embodiment, a smoke exhaust section 13 is provided on the lid body 10, but since the conductive member 12 is positioned near the longitudinal end of the battery cell 2, there is no interference between the conductive member 12 and the smoke exhaust section 13. Furthermore, if the lid 9 has a resistor 14 electrically connected to the conductive member 12, it is possible to prevent the conductive member 12 from being violently discharged when the battery cell 2 is externally short-circuited, thereby improving safety.

[0042] If the support portion 11 provided on the lid 9 is formed from a resin with a lower melting point than the lid body 10, even if the support portion 11 is formed to have the same thickness as the lid body 10, the high temperature heat of the released gas will melt the support portion 11 first, allowing the lid body 10 to fall. This ensures the rigidity of the lid 9 during normal times when no thermal runaway is occurring. On the other hand, if the shape of the support portion 11 is designed to melt the support portion 11 first, there is no need to change the material of the lid 9, and therefore the lid body 10 can be dropped with a simple configuration by utilizing the heat and momentum (pressure) generated when smoking occurs.

[0043] [2. Second embodiment] Next, a battery module 1' according to a second embodiment will be described. As described above, the battery module 1' according to the second embodiment differs from the first embodiment only in the external short-circuiting configuration, and the other configurations are the same. Below, configurations that differ from the first embodiment will be mainly described, and configurations that are common to the first embodiment will be assigned the same reference numerals and redundant description will be omitted.

[0044] Like the first embodiment, the battery module 1' of this embodiment also has a drop structure for the lid 9, and an electrically conductive member 12 that externally short-circuits the multiple battery cells 2 when the lid body 10 is dropped. As shown in Figures 4(a) and (b), the electrically conductive member 12 is attached in advance to the underside 10b of the lid body 10, and when the support part 11 dissolves and the lid body 10 drops, the electrically conductive member 12 drops together with the lid body 10 (as a single unit) and comes into contact with the electrode terminals 3 of the battery cells 2, as shown in Figure 5(a).

[0045] 4(a) and 4(b), in the battery module 1' of this embodiment, one battery cell 2 is externally short-circuited by one current-carrying member 12. That is, the number of current-carrying members 12 is the same as the number of battery cells 2. Since the battery module 1' of this embodiment has eight battery cells 2, eight current-carrying members 12 are provided.

[0046] As shown in Figures 4(b) and 5(b), the current-carrying member 12 is positioned so that when the lid body 10 falls, it electrically connects the positive electrode terminal 3P and the negative electrode terminal 3N of one battery cell 2. Note that Figure 5(b) is a cross-sectional view taken along the line EE in Figure 5(a), with the lid body 10 omitted from the illustration.

[0047] In this embodiment, the current-carrying member 12 is a rectangular plate that spans the positive electrode terminal 3P and negative electrode terminal 3N of each battery cell 2. The current-carrying member 12 illustrated here has a rectangular shape that extends in the longitudinal direction of the top surface 2a of each battery cell 2. As described above, the current-carrying member 12 is formed of a conductive material (for example, a metal such as copper or a conductive plastic). Also in this embodiment, the lid 9 may have a resistor 14 (see FIG. 6(a) and other figures, which will be described later) attached to the current-carrying member 12 so as to be electrically conductive. By increasing the resistance of the current-carrying member 12 with the resistor 14, severe discharge may be prevented in the event of an external short circuit.

[0048] The method of attaching the current-carrying members 12 to the underside 10b can be the same as that described in the first embodiment. In the battery module 1' of this embodiment, the current-carrying members 12 are attached to the underside 10b of the lid body 10 directly above each battery cell 2, and therefore the smoke exhaust section 13 is set in a position that does not interfere with the current-carrying members 12 (for example, between adjacent current-carrying members 12).

[0049] In the battery module 1' of this embodiment and a battery pack including the same, if the internal pressure of one of the battery cells 2 (smoke-emitting cells) increases, the safety valve 4 opens, and high-temperature released gas is released, the support portion 11 of the lid 9 melts, as in the first embodiment, and the lid body 10 falls, as shown in Fig. 5(a). As a result, as also shown in Fig. 5(b), each current-carrying member 12 attached to the underside 10b of the lid body 10 comes into contact with the electrode terminals 3 of each battery cell 2, causing an external short circuit in the multiple battery cells 2. The released gas is discharged to the outside through gaps around the periphery of the lid body 10 and the smoke exhaust portion 13.

[0050] Thus, in the battery module 1' of this embodiment and the battery pack including the same, if one battery cell 2 experiences thermal runaway, the released gas melts the support part 11, causing the lid body 10 of the battery case 2 to fall, and the current-carrying member 12 to externally short-circuit the multiple battery cells 2. As a result, as in the first embodiment, the energy of each battery cell 2 can be reduced, thereby suppressing the momentum of thermal runaway and preventing thermal runaway in adjacent battery cells 2. Therefore, if one battery cell 2 in the battery module 1' experiences thermal runaway, it is possible to prevent subsequent explosions of the other battery cells 2.

[0051] Furthermore, because one battery cell 2 is externally short-circuited using one current-carrying member 12, the short-circuiting of each battery cell 2 is not affected by the state of the other battery cells 2. This improves safety when short-circuiting the battery cells 2. In addition, the battery module 1' of this embodiment and the battery pack including the same can obtain the same effects as those of the first embodiment due to the same configuration.

[0052] [3. Other] The above-described configuration of the battery modules 1, 1' is an example. For example, in the second embodiment, the current-carrying members 12 are arranged in a straight line (rectangular shape) so that they will reliably contact the positive electrode terminals 3P and negative electrode terminals 3N of each battery cell 2 when the lid body 10 is dropped. However, the arrangement and shape of the current-carrying members 12 may be changed depending on the arrangement of the electrode terminals 3.

[0053] For example, as shown in Fig. 6(a), in the case where the positive electrode terminal 3P and the negative electrode terminal 3N of the battery cell 2 are obliquely arranged on one side and the other side of the short side direction (left-right direction in the figure) of the top surface 2a of the battery cell 2, the width dimension (length in the left-right direction in the figure) of the current-carrying member 12 may be made close to the width dimension of the top surface 2a. In other words, a current-carrying member 12 with a larger width than the current-carrying member 12 shown in Fig. 4(b) may be arranged so that the current-carrying member 12 reliably comes into contact with the positive electrode terminal 3P and the negative electrode terminal 3N when the lid body 10 is dropped.

[0054] Furthermore, as shown in FIG. 6(b), in accordance with the oblique arrangement of the positive electrode terminal 3P and the negative electrode terminal 3N, the current-carrying member 12 may also extend obliquely to connect the positive electrode terminal 3P and the negative electrode terminal 3N. Alternatively, as shown in FIG. 6(c), the current-carrying member 12 may be crank-shaped. In any of the configurations shown in FIGS. 6(a) to 6(c), when the lid body 10 falls, the current-carrying member 12 can externally short-circuit each battery cell 2. Note that in FIGS. 6(a) to 6(c), one resistor 14 is electrically connected substantially in the center of the current-carrying member 12, but the resistor 14 is not essential. Furthermore, even if resistors 14 are provided, their arrangement and number are not particularly limited.

[0055] The battery cell 2 in each of the above-described embodiments has a positive electrode terminal 3P and a negative electrode terminal 3N protruding upward from the upper surface 2a. However, as shown in FIGS. 7(a) and 7(b), a positive electrode active portion 3p and a negative electrode active portion 3n may be provided on the upper surface 2a of the battery cell 2. The positive electrode active portion 3p is electrically connected to the positive electrode terminal 3P, and the negative electrode active portion 3n is electrically connected to the negative electrode terminal 3N. In this case, the current-carrying member 12 of the second embodiment may be arranged to electrically connect the positive electrode active portion 3p and the negative electrode active portion 3n, instead of the positive electrode terminal 3P and the negative electrode terminal 3N, when the lid body 10 is dropped. With this configuration, the battery cell 2 can be externally short-circuited, as in the second embodiment.

[0056] Furthermore, when the battery cell 2 of the first embodiment has a positive electrode active portion 3p and a negative electrode active portion 3n on its upper surface 2a, as shown in Fig. 8, a current-carrying member 12 may be arranged so as to electrically connect the positive electrode active portion 3p of one battery cell 2 to the negative electrode active portion 3n of the other battery cell 2 when the lid body 10 is dropped. With this configuration, the battery cells 2 can be externally short-circuited, as in the first embodiment. Note that although the battery cells 2 shown in Figs. 7(a), (b), and 8 are also provided with a resistor 14, the resistor 14 can be omitted.

[0057] Additionally, the specific configuration and arrangement of the battery cells 2 are not limited to those described above. For example, the battery cells 2 do not have to be rectangular, and multiple battery cells 2 do not have to be arranged side by side in a horizontal row. Note that the use of a battery pack consisting of multiple battery modules 1, 1' is not limited to a vehicle drive battery. [Explanation of symbols]

[0058] 1,1' battery module 2 battery cells 2a Top side 3 electrode terminal 3N negative terminal 3n Negative active part 3P positive terminal 3p positive electrode live part 4 Safety valve 5. Heat insulating materials 6 Busbar 7 Battery case 8 Case body 9 Lid 10 Lid body 10b Bottom side 11 Support part 12 Current-carrying members 13 Smoke exhaust section 13h Smoke exhaust port 14 Resistor

Claims

1. A battery module in which a plurality of battery cells are housed side by side in a battery case, Each of the battery cells has a safety valve on its top surface that opens when internal pressure increases to release gas within the battery cell, the battery case includes a case body having an upper opening and accommodating the plurality of battery cells, and a lid attached to the case body and closing the upper opening; The lid is a lid body that covers the upper part of the plurality of battery cells; a support portion that supports the lid body relative to the case body and that dissolves when gas is released when the safety valve of any of the battery cells opens; a current-carrying member attached to the underside of the lid body, the support portion melting to cause an external short circuit between the plurality of battery cells when the lid body falls; A battery module comprising:

2. Two adjacent battery cells are externally short-circuited by one of the current-carrying members. The battery module according to claim 1 .

3. One of the battery cells is externally short-circuited by one of the current-carrying members. The battery module according to claim 1 .

4. The cover has a resistor attached to the conductive member so as to be conductive thereto. The battery module according to any one of claims 1 to 3.

5. A battery module according to any one of claims 1 to 3 is provided. A battery pack characterized by:

6. A battery module according to claim 4 is provided. A battery pack characterized by:

Images