Battery pack and battery assembly

Abstract

To provide a battery pack and a battery assembly that can alleviate increase of a pressure inside a case during thermal runaway of battery cells.SOLUTION: A battery pack 10 comprises: a cell laminate 30 in which a plurality of battery cells 40 each having a safety valve 44 is laminated; an exhaust duct 46 that connects the safety valves 44 with each other and extends in the lamination direction of the plurality of battery cells 40; and a case 20 in which the cell laminate 30 and the exhaust duct 46 are accommodated. The case 20 is provided with: a pressure release valve 13 that communicates with the exhaust duct 46 and an open space on the outside of the case 20, and can exhaust the gas discharged from the safety valves 44 of the battery cells 40 to the open space; and a check valve 15 that communicates with a sealed space on the outside of the case 20, and can exhaust the gas to the sealed space.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present invention relates to a battery pack and a battery assembly including a cell stack in which a plurality of battery cells are stacked. [Background technology]

[0002] In recent years, research and development into secondary batteries that contribute to energy efficiency has been conducted in order to ensure that more people have access to affordable, reliable, sustainable and advanced energy.

[0003] As vehicle drive sources become more electrically powered, vehicles are equipped with batteries that supply power to motors and other devices. A battery is, for example, configured by stacking multiple battery cells. A battery cell is provided with a valve that releases high-temperature, high-pressure gas generated inside the battery cell due to an abnormality or the like to the outside of the battery cell (for example, Patent Documents 1 and 2).

[0004] Patent document 2 also describes a gas exhaust structure for a battery module that includes a cell unit formed by stacking multiple cells each equipped with an explosion-proof valve, a module case that houses the cell unit, an internal pressure release section that penetrates the module case and releases gas accumulated inside to the outside, and a partition wall that is arranged between the cell unit and the internal pressure release section. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2003-178740 A [Patent Document 2] Patent No. 5939307 Summary of the Invention [Problem to be solved by the invention]

[0006] In Patent Document 2, although the case is provided with an internal pressure release section, when gas is released into the case from the explosion-proof valve of the cell due to thermal runaway, the inside of the case temporarily becomes high pressure. In order to reduce the impact on the outside caused by the pressure rise inside the case, a configuration that can appropriately alleviate the pressure rise inside the case is desired.

[0007] The present invention provides a battery pack and a battery assembly that can reduce the pressure rise inside the case when a battery cell experiences thermal runaway, thereby contributing to improved energy efficiency. [Means for solving the problem]

[0008] The present invention relates to a cell stack in which a plurality of battery cells each having a safety valve are stacked; an exhaust duct that connects the safety valves of each battery cell and extends in a stacking direction of the plurality of battery cells; A battery pack comprising: a case in which the cell stack and the exhaust duct are housed; In the case, a pressure relief valve that communicates with the exhaust duct and an open space outside the case and is capable of discharging gas released from the safety valve of the battery cell into the open space; A check valve is provided which communicates with a sealed space outside the case and is capable of discharging the gas into the sealed space.

[0009] The present invention also provides a method for producing a semiconductor device comprising the steps of: A plurality of battery packs; a conductive member accommodating portion in which a conductive member that connects the plurality of battery packs liquid-tightly and electrically connects the plurality of battery packs is disposed, Each battery pack is a cell stack in which a plurality of battery cells each having a safety valve are stacked; an exhaust duct that connects the safety valves of each battery cell and extends in a stacking direction of the plurality of battery cells; a case that houses the cell stack and the exhaust duct and is connected to the conductive member housing, In the case, a pressure relief valve that communicates with the exhaust duct and an open space outside the case and is capable of discharging gas released from the safety valve of the battery cell into the open space; A check valve is provided that communicates with the conductive member accommodating portion and is capable of discharging the gas to the conductive member accommodating portion. Effect of the Invention

[0010] According to the present invention, it is possible to mitigate the increase in pressure inside the case when a thermal runaway occurs in a battery cell. [Brief description of the drawings]

[0011] [Figure 1] 1 is an external perspective view of a battery pack 10. FIG. [Diagram 2] FIG. 2 is an exploded perspective view of the battery pack 10. [Diagram 3] FIG. 2 is an exploded perspective view of the cell stack 30. [Figure 4] FIG. 2 is an external perspective view of the battery assembly 100. [Diagram 5] 1 is an external perspective view of the battery assembly 100 seen from the bottom side with the bottom cover 126 disassembled. FIG. [Figure 6] FIG. 2 is an external perspective view of a central frame 120. [Figure 7] FIG. 2 is an external perspective view of a bulging portion 22. [Figure 8] 8 is a cross-sectional view taken along line AA in FIG. 7. [Figure 9] 13 is a diagram showing how gas generated during thermal runaway of a battery cell 40 is exhausted to the outside of the cell accommodating space 25 through an insertion hole 93. FIG. [Figure 10] 1 is a diagram showing the flow of gas within a battery assembly 100 when thermal runaway occurs in a certain battery pack 10. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the battery pack of the present invention will be described with reference to the accompanying drawings. For convenience, the following description will be given using a coordinate system consisting of a front-rear direction, a left-right direction, and an up-down direction that are mutually orthogonal. In the drawings, the front is indicated as Fr, the rear as Rr, the left side as L, the right side as R, the upside as U, and the downside as D. However, these directions are unrelated to the direction in which the battery pack is mounted on the device. For example, when the battery pack is mounted on a vehicle, the up-down direction of the battery pack may face the traveling direction of the vehicle when mounted on the vehicle, or may face the vehicle width direction.

[0013] [Battery pack] As shown in Fig. 1 and Fig. 2, the battery pack 10 has two cell stacks 30 arranged side by side in the front-rear direction inside a box-shaped case 20. As shown in Fig. 3, the cell stack 30 has a plurality of rectangular battery cells 40 stacked in the left-right direction and an end plate 31 arranged on one side in the left-right direction (the left side in this embodiment), which are temporarily fixed with a predetermined pressure by using a binder 50. Note that a separator (not shown) may be arranged between adjacent battery cells 40. The binder 50 includes a rectangular lower restraint portion 51 surrounding the bottom surface of the cell stack 30, a rectangular upper restraint portion 52 surrounding the top surface of the cell stack 30, and a pair of side restraint portions 53 that sandwich the cell stack 30 from the front-rear direction, and the lower restraint portion 51 and the pair of side restraint portions 53 are integrally formed. Note that another end plate, separator, etc. may be arranged on the other side in the left-right direction of the cell stack 30 (the right side in this embodiment) so that the battery cells 40 on the other side do not directly contact the case 20. Furthermore, the cell stack 30 does not have to be configured in such a way that the multiple battery cells 40 are restrained by the binder 50;

[0014] The battery cells 40 are, for example, secondary batteries such as lithium ion batteries. On the upper surface of the battery cell 40, a pair of terminals 42 are provided at both ends in the front-rear direction, which is a direction perpendicular to the stacking direction of the battery cells 40, and a safety valve 44 is provided in the center in the front-rear direction and disposed between the pair of terminals 42. The pair of terminals 42 includes a positive terminal and a negative terminal, and for example, the positive terminal is connected to the negative terminal of the adjacent battery cell 40 via a bus bar (not shown), and the negative terminal is connected to the positive terminal of the adjacent battery cell 40 via a bus bar (not shown), thereby electrically connecting the multiple battery cells 40 in series. For example, in order to shorten the length of the bus bar, the multiple battery cells 40 may be stacked so that the orientation in the front-rear direction is alternately reversed.

[0015] The safety valve 44 is a burst type valve that prevents the outer can from bursting when the internal pressure of the battery cell 40 increases abnormally. When the internal pressure of the battery cell 40 increases abnormally, the safety valve 44 bursts and the gas inside the battery cell 40 is released to the outside. By providing the safety valve 44 at the center in the front-to-rear direction of the battery cell 40, the battery cells 40 can be gathered in the same front-to-rear position even if they are stacked so that their front-to-rear orientations are alternately reversed.

[0016] The battery cells 40 are provided with an exhaust duct 46 that connects the safety valves 44 of multiple battery cells 40 and through which gas released from the safety valves 44 flows. For example, the exhaust duct 46 is formed by a hood that covers the safety valves 44. The exhaust duct 46 extends in the direction in which the safety valves 44 are lined up, i.e., in the stacking direction of the battery cells 40, and guides the gas toward the pressure release valve 13, which will be described later.

[0017] Returning to Fig. 2, the case 20 includes a case body 21 that is open at the top, and a case cover 23 that covers the opening of the case body 21. The case body 21 has a front wall portion 82 and a rear wall portion 84 that extend in the left-right direction, a left wall portion 86 that connects left ends of the front wall portion 82 and the rear wall portion 84, a right wall portion 87 that connects right ends of the front wall portion 82 and the rear wall portion 84, and a bottom wall portion 88. The space surrounded by the front wall portion 82, the rear wall portion 84, the left wall portion 86, and the right wall portion 87 constitutes a cell accommodating space 25 that accommodates the cell stack 30.

[0018] The left wall 86 is provided with an opening 86a that communicates the cell storage space 25 with the outside, and the pressure plate 28 is attached via a seal material 16 (e.g., a rubber seal). By fixing the pressure plate 28 to the left wall 86, the pressure plate 28 comes into contact with the end plates 31 of the respective cell stacks 30 through the opening 86a. By pressing the end plates 31 inward with the pressure plate 28, the cell stacks 30 temporarily fixed with a predetermined pressure by the binder 50 are further pressurized in the stacking direction and held within the case 20. The pressure plate 28 may be fixed to the left wall 86 by welding such as friction stir welding, or may be fixed with bolts. In this way, in the battery pack 10, a plurality of battery cells 40 can be held within the case 20 without being modularized, and therefore energy density and space efficiency can be improved.

[0019] 1, the pressure plate 28 is provided with two pressure release valves 13 that communicate with the cell accommodating space 25. The pressure release valves 13 open when gas generated from a safety valve 44 of a battery cell 40 causes an abnormal increase in the internal pressure of the cell accommodating space 25, and release the gas inside the case 20 to the outside.

[0020] Further, in front of and to the left of the front wall 82, a bulging portion 22 is formed so as to protrude further forward from the front wall 82. A space is formed inside the bulging portion 22, and a first opening 91 is provided on the front surface, and a second opening 92 is also provided on the upper surface. A terminal block 60 to which the output conductive member 70 is connected is provided in the internal space of the bulging portion 22, forming the output terminal accommodating space 27. In the terminal block 60, a terminal portion (output terminal) of the output conductive member 61 extending from the cell accommodating space 25 to the output terminal accommodating space 27 is electrically connected to a terminal portion of the output conductive member 70 entering the output terminal accommodating space 27 from the first opening 91. The output conductive member 61 includes a positive side bus bar 62 and a negative side bus bar 63 extending from the positive side output terminal and the negative side output terminal of the two cell stacks 30 electrically connected in series, respectively. The output conductive member 70 includes, for example, a positive bus bar 72 and a negative bus bar 73 that are connected to an external positive terminal and a negative terminal, respectively.

[0021] Thus, the inside of the case 20 is provided with a cell accommodating space 25 that accommodates the two cell stacks 30, and an output terminal accommodating space 27 that is disposed in front of and to the left of the cell accommodating space 25 and to which the output conductive member 70 is connected. The number of cell stacks 30 accommodated in the cell accommodating space 25 may be one, or three or more.

[0022] In the front wall portion 82, a region separating the cell accommodating space 25 and the output terminal accommodating space 27 (hereinafter, this portion is referred to as a partition portion 85) is lower in height than other regions. A gap is provided between the upper end of the partition portion 85 and the case cover 23, and this gap serves as an insertion opening 93 through which the output conductive member 61 can be inserted (see FIG. 8). The output conductive member 61 has an inverted L-shape, with one end extending forward from the insertion opening 93 into the output terminal accommodating space 27 and the other end extending downward and fixed to a terminal block 60 provided in the output terminal accommodating space 27.

[0023] 1, a signal line connector 67 is provided in the output terminal accommodating space 27. A signal line is connected to the signal line connector 67 via a through hole that connects the cell accommodating space 25 and the output terminal accommodating space 27.

[0024] A case cover 23 is attached to the top surface of the case body 21 via a first seal material 11 (e.g., a rubber seal). The case cover 23 is fixed to the top surface of the case body 21 by welding, for example, by friction stir welding. By sealing the cell accommodating space 25 from the outside, intrusion of foreign matter into the cell accommodating space 25 is suppressed, and deterioration of the battery cells 40 can be suppressed.

[0025] The battery pack 10 configured in this manner does not include auxiliary devices such as a junction box that houses a contactor, a fuse, etc., and an ECU. Therefore, when the battery pack 10 is used alone, a junction box and / or an ECU may be connected to the battery pack 10. When a plurality of battery packs 10 are used, the battery packs 10 may be electrically connected to each other through a connection box, and the junction box and / or an ECU may be connected to the connection box. Also, the junction box and / or an ECU may be built into the connection box, and the plurality of battery packs 10 may be connected to the junction box and / or the ECU within the connection box.

[0026] Next, a battery pack mounting structure in which four battery packs 10 are mounted under the floor of a vehicle will be described with reference to Figures 4 to 6. In the following description, the front-rear direction, left-right direction (vehicle width direction), and up-down direction are defined based on the vehicle.

[0027] In this mounting structure, as shown in Fig. 4, a central frame 120 extending in the vehicle width direction is fixed between a left side frame 110L and a right side frame 110R extending in the front-rear direction of the vehicle. In addition, the two battery packs 10 described above are arranged side by side in the space in front of the central frame 120, and the two battery packs 10 described above are arranged side by side in the space behind the central frame 120. The four battery packs 10 are fixed to and supported by the left side frame 110L, the right side frame 110R, and the central frame 120. Hereinafter, this structure is referred to as a battery assembly 100.

[0028] [Battery Assembly] In the battery assembly 100, the two front battery packs 10 are arranged so that the bulging portions 22 are located rearward and to the right, and the two rear battery packs 10 are arranged so that the bulging portions 22 are located forward and to the left. That is, the two front battery packs 10 and the two rear battery packs 10 are arranged in a state rotated 180° so that the bulging portions 22 face each other in the front-rear direction with the central frame 120 in between.

[0029] As shown in FIG. 6, the central frame 120 of the battery assembly 100 is a hollow body with a rectangular cross-section, and is fastened to the left and right side frames 110L and 110R by flange portions 127 formed on the left and right ends and extending in the front-to-rear direction.

[0030] Two front communication holes 121a are formed in the front surface 121 of the central frame 120, each of which communicates with a first opening 91 formed in the bulging portion 22 of the front battery pack 10. Similarly, two rear communication holes 122a are formed in the rear surface 122 of the central frame 120, each of which communicates with a first opening 91 formed in the bulging portion 22 of the rear battery pack 10. The front communication holes 121a and the rear communication holes 122a are offset in the vehicle width direction. That is, the center position of the front communication hole 121a in the vehicle width direction and the center position of the rear communication hole 122a in the vehicle width direction are offset in the vehicle width direction.

[0031] Fastening portions 123 for fastening the corresponding battery packs 10 in a liquid-tight manner are provided around the front communication holes 121a and the rear communication holes 122a, and each battery pack 10 is fixed to the central frame 120 by, for example, bolt fastening. The central frame 120 has fastening portions 123 on the front surface 121 and the rear surface 122, respectively, and the front surface 121 and the rear surface 122 protrude upward and downward, so that a cross section cut in the front-to-rear direction has a highly rigid cross-sectional shape like an H-shaped steel beam.

[0032] From the output terminal accommodating space 27 formed in the bulging portion 22 of each battery pack 10, the output conductive member 70 passes through the first opening 91 and enters the hollow region 125 of the central frame 120. As shown in FIG. 5, a bus bar unit 140 is disposed in the hollow region 125 of the central frame 120. The bus bar unit 140 includes, for example, a plurality of connecting bus bars, and electrically connects the four battery packs 10, for example, in series. The central frame 120 is an example of the above-mentioned connection box. The hollow region 125 of the central frame 120 corresponds to the "sealed space" and the "conductive member accommodating portion" of the present invention.

[0033] A bottom opening 124 is provided on the rear surface of the central frame 120, and the bottom opening 124 is liquid-tightly closed by a bottom cover 126 via a sealing member (not shown). Since the bottom opening 124 of the central frame 120 is liquid-tightly closed by the bottom cover 126 and the communication holes 121a, 122a of the central frame 120 and the first opening 91 of each battery pack 10 are liquid-tightly fastened to each other, intrusion of moisture from the outside into the output terminal accommodating space 27 of the battery pack 10 and the hollow region 125 of the central frame 120 is restricted. The extraction conductive member 70 extending from each battery pack 10 to the hollow region 125 of the central frame 120 is fastened to the bus bar unit 140 from the bottom opening 124 with the bottom cover 126 removed.

[0034] The battery assembly 100 thus configured is fixed to the frame members of the vehicle by a pair of central supports 128 provided on the central frame 120 and side supports 111 provided on the left side frame 110L and the right side frame 110R, and is placed under the floor of the vehicle.

[0035] [Gas exhaust structure] If some abnormality occurs in the battery cell 40, such as an internal short circuit, the battery cell 40 may experience thermal runaway, which is abnormal heat generation, and generate high-temperature, high-pressure gas inside the battery cell 40. If the pressure of the gas generated inside the battery cell 40 rises above a predetermined value, the safety valve 44 will burst and the gas will be released outside the battery cell 40, i.e., inside the case 20.

[0036] The battery pack 10 is provided with the above-mentioned pressure relief valve 13 in order to exhaust gas that fills the inside of the case 20 to the outside of the case 20 in the event of thermal runaway. However, since the cell stack 30 is pressurized by the pressure plate 28 and densely arranged in the case 20, the gap between the cell stack 30 and the case 20 is small, and the inside of the case 20 is likely to become highly pressurized when gas is released from the safety valve 44. Therefore, in addition to the pressure relief valve 13, the battery pack 10 is preferably provided with a configuration for mitigating the pressure rise inside the case 20.

[0037] 7 to 9, the battery pack 10 further includes a check valve 15. The check valve 15 communicates with a hollow area 125 of the central frame 120 on the outside of the case 20, and is configured to be able to exhaust gas filling the cell accommodating space 25 to the hollow area 125.

[0038] When the pressure in the cell accommodating space 25 rises due to thermal runaway of the battery cell 40, the pressure release valve 13 opens, discharging the gas filling the cell accommodating space 25 to the open space outside the case 20, thereby releasing the pressure in the cell accommodating space 25. Furthermore, the check valve 15 also opens, discharging the gas into the hollow space 125 of the central frame 120, which is a sealed space, thereby mitigating the pressure rise in the cell accommodating space 25 at the initial stage of thermal runaway of the battery cell 40. In this way, the battery pack 10 opens at two points, the pressure release valve 13 and the check valve 15, during thermal runaway of the battery cell 40, so that the pressure can be appropriately released and the pressure rise inside the case 20 can be mitigated. Therefore, the impact during thermal runaway can be mitigated, and the impact on the outside due to the pressure rise in the case 20 can be suppressed.

[0039] Furthermore, because hollow region 125 is an enclosed space, after a certain amount of gas has flowed into hollow region 125 (i.e., after the initial stage of thermal runaway), the flow of gas toward hollow region 125 subsides. After the initial stage of thermal runaway, substances such as the electrolyte and electrodes of battery cell 40 (hereinafter also referred to as cell contents) may be released from safety valve 44, but because the flow of gas toward hollow region 125 has subsided, the cell contents do not flow into hollow region 125 but are guided to pressure release valve 13 and discharged to the outside of case 20. This makes it possible to prevent the cell contents from causing a short circuit in busbar unit 140 in hollow region 125.

[0040] Furthermore, since the check valve 15 has a function of regulating the flow of gas from the outside of the case 20, even if thermal runaway occurs in the battery pack 10 arranged on the front and right side of the battery assembly 100 and gas is released from that battery pack 10 into the hollow area 125 of the central frame 120, as shown in Fig. 10, the check valve 15 prevents gas from flowing into the other three battery packs 10. Therefore, it is possible to prevent a chain reaction of thermal runaway occurring in one battery pack 10 causing thermal runaway in the other battery packs 10.

[0041] The following describes an example of a specific configuration of the check valve 15. Note that the configuration of the check valve 15 is not limited to this example, and various configurations can be adopted.

[0042] 8, the check valve 15 of this embodiment is provided in the case 20 so as to cover the insertion hole 93 through which the output conductive member 61 is inserted. The check valve 15 is provided outside the cell accommodating space 25, specifically in the output terminal accommodating space 27, and covers the insertion hole 93 from the output terminal accommodating space 27 side. The insertion hole 93 and the check valve 15 are provided to extend in the left-right direction along the partition wall portion 85.

[0043] The check valve 15 normally covers the insertion hole 93 and part of the output conductive member 61 via the sealing material 12 (for example, a foam seal) and seals the cell accommodating space 25 together with the case cover 23. On the other hand, as shown in Figure 9, when the pressure in the cell accommodating space 25 increases due to thermal runaway of the battery cell 40, the check valve 15 opens to exhaust gas from the insertion hole 93 to the hollow area 125 of the central frame 120, thereby releasing the pressure in the cell accommodating space 25.

[0044] More specifically, the check valve 15 is a substantially L-shaped plate member. One end side 151 of the check valve 15 extends horizontally and is fixed to the lower surface of the case cover 23 outside the cell accommodating space 25. The one end side 151 may be fixed to the case cover 23 by, for example, a fastening member such as a bolt, or by welding such as friction stir welding.

[0045] The other end 152 of the check valve 15 extends in the vertical direction and covers the insertion opening 93 via the sealant 12. The other end 152 is provided in close contact with the partition wall portion 85 and the output conductive member 61 via the sealant 12. In this way, the check valve 15, together with the sealant 12, covers the insertion opening 93 through which the output conductive member 61 is inserted, thereby ensuring the airtightness of the cell accommodating space 25. In addition, intrusion of foreign matter into the cell accommodating space 25 from the insertion opening 93 can be suppressed.

[0046] 9, when thermal runaway of the battery cell 40 causes gas to fill the cell accommodating space 25 and the pressure in the cell accommodating space 25 to rise, the check valve 15 deforms and the insertion hole 93 opens. The check valve 15 has a bent portion 153 between one end side 151 and the other end side 152, and rotates about the bent portion 153 due to gas pressure to exhaust the gas into the hollow space 125 of the central frame 120. In other words, the check valve 15 is configured as a flap whose one end side 151 is fixed and whose other end side 152 rotates about the bent portion 153.

[0047] In this way, the check valve 15 covers the insertion hole 93 through which the output conductive member 61 is inserted to ensure the airtightness of the cell accommodating space 25, while when the pressure in the cell accommodating space 25 rises, it can release the pressure by venting the gas to the hollow area 125 of the central frame 120. Also, the check valve 15 is a substantially L-shaped plate member that can be deformed relatively easily, i.e., can rotate about the bent portion 153, so that the pressure in the cell accommodating space 25 can be released without the case body 21 or the case cover 23 bursting.

[0048] Furthermore, the pressure release valve 13 is provided in a position in the stacking direction with respect to the cell stack 30, specifically on the left wall portion 86, whereas the check valve 15 is provided in a position in a direction perpendicular to the stacking direction with respect to the cell stack 30, specifically on the front. That is, the pressure release valve 13 and the check valve 15 are provided in different directions when viewed from the cell stack 30, so that when the cell contents are guided to the pressure release valve 13 along the stacking direction, they can be prevented from flowing toward the check valve 15.

[0049] In addition, a pair of terminal portions 42 of each battery cell 40 are provided at both ends (i.e., the front and rear) in a direction perpendicular to the stacking direction, sandwiching the safety valve 44 therebetween, so that when the cell contents are guided to the pressure release valve 13 along the stacking direction, the cell contents can be prevented from adhering to the terminal portions 42 and causing a short circuit.

[0050] In addition, since the check valve 15 is arranged in a direction perpendicular to the stacking direction with respect to the cell stack 30, when the cell contents are guided along the stacking direction to the pressure release valve 13, it is possible to prevent the cell contents from adhering to the output conductive member 61 and the extraction conductive member 70 arranged in the vicinity of the check valve 15 and causing a short circuit.

[0051] In addition, since the insertion hole 93 and the check valve 15 are provided to extend in the left-right direction, it is possible to provide a wide exhaust port when exhausting gas to the hollow area 125. Therefore, the pressure in the cell accommodating space 25 can be sufficiently released.

[0052] Although one embodiment of the present invention has been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such an embodiment. It is clear that a person skilled in the art can come up with various modified or revised examples within the scope of the claims, and it is understood that these also naturally belong to the technical scope of the present invention. In addition, the components in the above embodiment may be arbitrarily combined within the scope of the invention.

[0053] For example, in the above-described embodiment, the battery assembly 100 is composed of four battery packs 10, two on each of the front, rear, left and right sides, but this is not limited to the above, and the battery assembly 100 may be composed of one on each of the front and rear sides, for a total of two battery packs 10, or two or more battery packs 10 may be arranged on the front and rear sides and two or more on the left and right sides.

[0054] In the above-described embodiment, the check valve 15 communicates with the hollow region 125 of the central frame 120 in which the busbar unit 140 is disposed, but this is not limited thereto. For example, the check valve 15 may be configured to communicate with an enclosed space in which an electric device other than the busbar unit 140 is disposed. In addition, for example, when the battery pack 10 is used alone instead of as the battery assembly 100, a box or tank constituting the enclosed space may be provided so as to communicate with the first opening 91, and the check valve 15 may be configured to communicate with the enclosed space.

[0055] This specification describes at least the following items. In parentheses, components corresponding to the above-described embodiment are shown as examples, but the present invention is not limited to these.

[0056] (1) A cell stack (cell stack 30) in which a plurality of battery cells (battery cells 40) each having a safety valve (safety valve 44) are stacked, an exhaust duct (exhaust duct 46) that connects the safety valves of each battery cell and extends in the stacking direction of the plurality of battery cells; A battery pack (battery pack 10) comprising: a case (case 20) in which the cell stack and the exhaust duct are housed; In the case, a pressure relief valve (pressure relief valve 13) that communicates with the exhaust duct and an open space outside the case and that is capable of discharging gas released from the safety valve of the battery cell into the open space; the battery pack is provided with a check valve (check valve 15) that communicates with a sealed space (hollow region 125) outside the case and is capable of discharging the gas into the sealed space.

[0057] According to (1), the case is provided with a check valve that communicates with the sealed space, so that when high-pressure gas is generated from the safety valve of the battery cell due to thermal runaway, the check valve opens to release the pressure inside the case in the early stages of thermal runaway, and the pressure rise inside the case can be alleviated. In addition, after gas has flowed into the sealed space, the flow of gas toward the check valve stops, so the gas and the cell contents that may be generated along with the gas can be discharged to the outside of the case through the pressure release valve that communicates with the open space.

[0058] (2) A battery pack according to (1), the pressure release valve is provided at a position in the stacking direction with respect to the cell stack, The check valve is provided at a position perpendicular to the stacking direction of the cell stack. Battery pack.

[0059] According to (2), when the cell contents that may be released from the safety valve of the battery cell due to thermal runaway or the like are guided toward the pressure release valve, they can be prevented from flowing toward the check valve.

[0060] (3) A battery pack according to (2), The sealed space is a conductive member accommodating portion (hollow region 125) in which a first conductive member (bus bar unit 140) that electrically connects the battery pack to another battery pack is disposed. Battery pack.

[0061] According to (3), in the early stage of thermal runaway, gas is exhausted from the check valve into the conductive material housing, which is an enclosed space, and the pressure inside the case can be released to the conductive material housing. Moreover, unlike the pressure release valve, the check valve is provided in a direction perpendicular to the stacking direction of the cell stack, so that the flow of the cell contents toward the conductive material housing can be further suppressed.

[0062] (4) A battery pack according to (3), Each battery cell is The safety valve is provided at a center portion in a direction perpendicular to the stacking direction; and terminal portions (terminal portions 42) provided at both ends in a direction perpendicular to the stacking direction. Battery pack.

[0063] According to (4), the terminal portions of each battery cell are provided at both ends in a direction perpendicular to the stacking direction. Therefore, when the cell contents released from the safety valve due to thermal runaway are guided toward the pressure release valve, the cell contents can be prevented from flowing toward the terminal portions of each battery cell and causing a short circuit.

[0064] (5) A battery pack according to (4), a second conductive member (output conductive member 61) electrically connecting the terminal portion and the first conductive member disposed in the conductive member accommodating portion, The check valve is provided in the vicinity of the second conductive member. Battery pack.

[0065] According to (5), the cell contents released from the safety valve due to thermal runaway are guided toward the pressure release valve without flowing to the check valve, thereby preventing the cell contents from flowing into the second conductive member located close to the check valve and causing a short circuit.

[0066] (6) The battery pack according to (5), In the case, a case body (case body 21) having a bottom wall portion (bottom wall portion 88) and a vertical wall portion (partition wall portion 85) erected from the bottom wall portion; and a case cover (case cover 23) that covers the case body from above, Between the vertical wall portion and the case cover, an opening (insertion hole 93) through which the second conductive member is inserted from the terminal portion toward the conductive member accommodating portion is provided, The check valve is provided so as to cover the opening via a sealant (sealant 12). Battery pack.

[0067] According to (6), the check valve and sealing material cover the opening through which the second conductive member is inserted, sealing the case, and can open the opening to release pressure inside the case in the event of thermal runaway of the battery cell.

[0068] (7) A battery pack according to any one of (1) to (6), The check valve is a substantially L-shaped plate member that covers an opening (insertion opening 93) that communicates between the inside of the case and the sealed space, one end side (one end side 151) is fixed to the case, and the other end side (other end side 152) covers the opening via a seal material (seal material 12); When the gas is released from the safety valve of the battery cell, the other end rotates around a bent portion (bent portion 153) provided between the one end and the other end. Battery pack.

[0069] According to (7), the check valve and sealing material cover the opening that leads to the sealed space, sealing the inside of the case, while being able to open the opening to release the pressure inside the case in the event of thermal runaway of the battery cell.

[0070] (8) A battery pack according to any one of (1) to (7), The cell stack is pressed against the case in a stacking direction of the plurality of battery cells and is accommodated in the case. Battery pack.

[0071] According to (8), even in a battery pack in which the cell stack is pressed and tightly housed inside the case, the check valve can appropriately suppress a pressure increase inside the case.

[0072] (9) a plurality of battery packs (battery packs 10); a conductive member accommodating portion (hollow region 125) in which a conductive member (bus bar unit 140) that connects the plurality of battery packs in a liquid-tight manner and electrically connects the plurality of battery packs is disposed, Each battery pack is a cell stack (cell stack 30) in which a plurality of battery cells (battery cells 40) each having a safety valve (safety valve 44) are stacked; an exhaust duct (exhaust duct 46) that connects the safety valves of each battery cell and extends in the stacking direction of the plurality of battery cells; a case (case 20) in which the cell stack and the exhaust duct are housed and which is connected to the conductive member housing portion; In the case, a pressure relief valve (pressure relief valve 13) that communicates with the exhaust duct and an open space outside the case and that is capable of discharging gas released from the safety valve of the battery cell into the open space; the battery assembly further comprising a check valve (check valve 15) that communicates with the conductive member accommodating portion and is capable of discharging the gas to the conductive member accommodating portion.

[0073] According to (9), the case is provided with a check valve that communicates with the conductive material accommodating section, which is an enclosed space, so that when high-pressure gas is generated from the safety valve of the battery cell due to thermal runaway, the check valve can vent the gas to the conductive material accommodating section in the early stages of gas generation, thereby mitigating the pressure rise inside the case. Also, due to the airtightness of the conductive material accommodating section, the flow of gas toward the check valve stops after it flows into the conductive material accommodating section, so the gas and the cell contents that may be generated along with the gas can be discharged to the outside of the case through the pressure release valve that communicates with the open space. [Explanation of symbols]

[0074] 10 Battery pack 12 Sealing material 13 Pressure relief valve 15 Check valve 151 One end side 152 Other end side 153 Bend 20 cases 21 Case body 23 Case cover 30 Cell stack 40 Battery Cells 42 Terminal section 44 Safety valve 46 Exhaust Duct 61 Output conductive member (second conductive member) 85 Partition wall (vertical wall) 88 Bottom wall 93 Insertion hole (opening) 100 Battery assembly 125 Hollow area (conductive material storage area, sealed space) 140 busbar unit (first conductive member)

Claims

1. a cell stack in which a plurality of battery cells each having a safety valve are stacked; an exhaust duct that connects the safety valves of each battery cell and extends in a stacking direction of the plurality of battery cells; A battery pack comprising: a case in which the cell stack and the exhaust duct are housed; In the case, a pressure relief valve that communicates with the exhaust duct and an open space outside the case and is capable of discharging gas released from the safety valve of the battery cell into the open space; the battery pack is provided with a check valve that communicates with a sealed space outside the case and is capable of discharging the gas into the sealed space.

2. 2. The battery pack according to claim 1, the pressure release valve is provided at a position in the stacking direction with respect to the cell stack, The check valve is provided at a position perpendicular to the stacking direction of the cell stack. Battery pack.

3. 3. The battery pack according to claim 2, the sealed space is a conductive member accommodating portion in which a first conductive member that electrically connects the battery pack to another battery pack is disposed. Battery pack.

4. 4. The battery pack according to claim 3, Each battery cell is The safety valve is provided at a center portion in a direction perpendicular to the stacking direction; and terminal portions provided at both ends in a direction perpendicular to the stacking direction. Battery pack.

5. 5. The battery pack according to claim 4, a second conductive member electrically connecting the terminal portion and the first conductive member disposed in the conductive member accommodating portion, The check valve is provided in the vicinity of the second conductive member. Battery pack.

6. 6. The battery pack according to claim 5, In the case, a case body having a bottom wall portion and a vertical wall portion erected from the bottom wall portion; a case cover that covers the case body from above, an opening through which the second conductive member is inserted from the terminal portion toward the conductive member accommodating portion is provided between the vertical wall portion and the case cover; The check valve is provided to cover the opening via a sealing material. Battery pack.

7. 7. The battery pack according to claim 1, The check valve is a substantially L-shaped plate member that covers an opening that communicates between the inside of the case and the sealed space, the plate member having one end fixed to the case and the other end covering the opening via a sealing material; When the gas is released from the safety valve of the battery cell, the other end rotates around a bent portion provided between the one end and the other end. Battery pack.

8. 7. The battery pack according to claim 1, The cell stack is pressed against the case in a stacking direction of the plurality of battery cells and is accommodated in the case. Battery pack.

9. A plurality of battery packs; a conductive member accommodating portion in which a first conductive member that connects the plurality of battery packs liquid-tightly and electrically connects the plurality of battery packs is disposed, Each battery pack is a cell stack in which a plurality of battery cells each having a safety valve are stacked; an exhaust duct that connects the safety valves of each battery cell and extends in a stacking direction of the plurality of battery cells; a case that houses the cell stack and the exhaust duct and is connected to the conductive member housing, In the case, a pressure relief valve that communicates with the exhaust duct and an open space outside the case and is capable of discharging gas released from the safety valve of the battery cell into the open space; a check valve communicating with the conductive member accommodating portion and capable of discharging the gas to the conductive member accommodating portion.

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