Battery pack

Abstract

The present invention relates to a battery pack capable of appropriately discharging gas to the outside of a case while suppressing a pressure increase in the case due to the gas generated during thermal runaway of a single cell. A battery pack is provided with: a plurality of stacked unit cells (40) having safety valves (44); end plates (31) provided at the ends of the single cells (40) in the stacking direction; an exhaust passage (46) that connects the relief valves (44) of the individual cells (40); a housing (20) for housing the first and second housing units; and a pressure relief valve (13) which is attached to a surface of the housing (20) facing the end plate (31), and which is capable of discharging the gas released from the relief valve (44) to the outside of the housing (20). Between the exhaust passage (46) and the pressure relief valve (13): a cushion space (47) formed around the end plate (31) and communicating with the exhaust passage (46); and a plurality of exhaust flow paths (48) connecting the cushion space and the pressure relief valve.

Description

Technical Field

[0001] The present invention relates to a battery pack in which a plurality of stacked single cells are arranged in a case. Background Art

[0002] In recent years, in order to ensure that more people have access to affordable, reliable, and sustainable modern energy, research and development related to secondary batteries that contribute to energy efficiency improvement have been underway.

[0003] With the electrification of vehicle drive sources, vehicles are equipped with storage batteries that supply power to motors and the like. The storage battery is constituted by, for example, stacking a plurality of single cells. The single cell is provided with a safety valve for releasing high-temperature and high-pressure gas generated inside due to abnormalities or the like to the outside of the single cell.

[0004] For example, Patent Document 1 describes the following battery module: single cells each provided with a safety valve in a case are arranged and connected, an exhaust passage is provided through a cover covering the arranged safety valves, end plates are respectively overlapped on the outermost single cells in the arrangement, and two end plates sandwich a plurality of single cells and are fixed. A conduction port communicating with the exhaust passage and an exhaust port communicating with the conduction port are provided in either one of the end plates.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2012-79510 Summary of the Invention

[0008] Problems to be Solved by the Invention

[0009] When the battery module described in Patent Document 1 is housed in a case to form a battery pack, if thermal runaway occurs in the battery module, gas is discharged from the exhaust port of the end plate and the inside of the case is filled with gas. In order to reduce the influence on the outside due to the pressure increase inside the case, a structure that can appropriately discharge the gas inside the case to the outside of the case and suppress the pressure increase inside the case is desired.

[0010] The present invention provides a battery pack that can suppress the pressure increase inside the case caused by gas generated during thermal runaway of a single cell and appropriately discharge the gas to the outside of the case. Furthermore, it contributes to improving energy efficiency.

[0011] Means for Solving the Problems

[0012] The present invention relates to a battery pack including:

[0013] a plurality of stacked single cells having safety valves;

[0014] An end plate, which is provided at an end portion of the single cell in the stacking direction;

[0015] An exhaust passage, which connects the safety valves of the respective single cells and extends in the stacking direction;

[0016] A housing, which houses the single cell, the end plate, and the exhaust passage; and

[0017] A pressure release valve, which is installed on a surface of the housing facing the end plate and can discharge the gas released from the safety valve to the outside of the housing, wherein

[0018] Between the exhaust passage and the pressure release valve, there is provided:

[0019] A space formed around the end plate and communicating with the exhaust passage; and

[0020] A plurality of flow paths connecting the space and the pressure release valve.

[0021] Advantages of the Invention

[0022] According to the present invention, it is possible to suppress an increase in the pressure inside the housing caused by the gas generated during thermal runaway of the single cell and appropriately discharge the gas to the outside of the housing. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is an external perspective view of the battery pack 10 of the first embodiment.

[0024] Figure 2 is an exploded perspective view of the battery pack 10 of the first embodiment.

[0025] Figure 3 is an exploded perspective view of the single cell stack 30.

[0026] Figure 4 shows the process of pressurizing a plurality of single cells 40 and housing them in the housing main body 21.

[0027] Figure 5 shows the flow of the gas guided to the pressure release valve 13 (dashed arrow).

[0028] Figure 6 is a partial cutaway perspective view near the pressure release valve 13.

[0029] Figure 7 is an exploded perspective view of the battery pack 10 of the second embodiment.

[0030] Figure 8 is a cross-sectional view of the pressing plate 28 in a state of pressing a plurality of single cells 40 and the end plate 31.

[0031] Figure 9 Shows the flow of gas (dashed arrows) in the buffer space 47 formed around the end plate 31 and in the plurality of exhaust flow paths 48 provided on the pressure plate 28.

[0032] Description of Reference Numerals

[0033] 10 Battery pack

[0034] 13 Pressure relief valve

[0035] 16 Spacer

[0036] 16f Flange portion

[0037] 20 Housing

[0038] 28 Pressure plate

[0039] 281 Flange portion

[0040] 282 Protrusion

[0041] 31 End plate

[0042] 31f Flange portion

[0043] 40 Single cell

[0044] 44 Safety valve

[0045] 46 Exhaust passage

[0046] 47 Buffer space (space)

[0047] 48 Exhaust flow path (flow path)

[0048] 86b Opening. Detailed Description of the Invention

[0049] Hereinafter, each embodiment of the battery pack of the present invention will be described with reference to the drawings. In addition, in the following description, for convenience, a coordinate system composed of the front-rear direction, left-right direction, and up-down direction that are orthogonal to each other will be used for the description. In the drawings, the front is represented as Fr, the rear is represented as Rr, the left side is represented as L, the right side is represented as R, the upper side is represented as U, and the lower side is represented as D. However, these directions are independent of the direction when 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 can be oriented in the traveling direction of the vehicle or in the vehicle width direction when mounted on the vehicle.

[0050] (First Embodiment)

[0051] [Battery pack]

[0052] First, the battery pack of the first embodiment will be described. As Figure 1 andFigure 2 As shown, two single - cell stacks 30 are arranged in the front - rear direction inside a box - shaped housing 20 of the battery pack 10. As Figure 3 shown, the single - cell stack 30 has a plurality of square single cells 40 stacked in the left - right direction and an end plate 31 disposed on one side in the left - right direction (the left side in this embodiment), and they are temporarily fixed with a prescribed pressure by using a plate clamp 50. Additionally, a separator (not shown) may be disposed between adjacent single cells 40. The plate clamp 50 has a rectangular lower restraint portion 51 surrounding the bottom surface of the single - cell stack 30, a rectangular upper restraint portion 52 surrounding the upper surface of the single - cell stack 30, and a pair of side restraint portions 53 sandwiching the single - cell stack 30 in the front - rear direction, and the lower restraint portion 51 and the pair of side restraint portions 53 are integrally formed. Additionally, it may be configured such that another end plate, separator, etc. are disposed on the other side in the left - right direction of the single - cell stack 30 (the right side in this embodiment) so that the single cells 40 do not directly contact the housing 20 on the other side. Additionally, the single - cell stack 30 may not be a structure in which a plurality of single cells 40 are restrained by a plate clamp 50, that is, it may be a structure in which a plurality of single cells 40 are directly stacked and disposed inside the housing 20.

[0053] The end plate 31 has flange portions 31f at the lower end and the upper end, and the flange portions 31f are restrained by the lower restraint portion 51 and the upper restraint portion 52, whereby the end plate 31 is fixed to the plurality of single cells 40. Due to the provision of the flange portions 31f, the contact surface between the end plate 31 and the single cells 40 becomes wider, and it is possible to suppress the reaction force from the end plate 31 being locally applied to the single cells 40.

[0054] The single cell 40 is, for example, a secondary battery such as a lithium - ion battery. On the upper surface of the single cell 40, there are provided: a pair of terminal portions 42 provided at both ends in the front - rear direction, which is the direction orthogonal to the stacking direction of the single cells 40; and a safety valve 44 provided at the central portion in the front - rear direction and disposed between the pair of terminal portions 42. The pair of terminal portions 42 includes a positive terminal and a negative terminal. For example, the positive terminal is connected to the negative terminal of an adjacent single cell 40 via a bus bar (not shown), and the negative terminal is connected to the positive terminal of an adjacent single cell 40 via a bus bar (not shown), whereby a plurality of single cells 40 are electrically connected in series. For example, in order to shorten the length of the bus bar, a plurality of single cells 40 may be stacked in an alternately flipped manner in the front - rear direction.

[0055] The safety valve 44 is a rupture-type valve that prevents the outer can from rupturing when the internal pressure of the single cell 40 abnormally rises. When the internal pressure of the single cell 40 abnormally rises, the safety valve 44 ruptures, and the gas in the single cell 40 is released to the outside. By disposing the safety valve 44 at the central portion in the front-back direction of the single cell 40, even when a plurality of single cells 40 are stacked in a manner of alternately flipping the front-back orientation, the gas can be collected at the same position in the front-back direction.

[0056] An exhaust passage 46 is provided in the single cell 40. The exhaust passage 46 connects the safety valves 44 of a plurality of single cells 40 and allows the gas released from the safety valves 44 to flow therethrough. For example, the exhaust passage 46 is constituted by a cover that covers the safety valve 44. The exhaust passage 46 extends in the direction in which the safety valves 44 are arranged, that is, the stacking direction of the single cells 40, and guides the gas to the pressure release valve 13 described below.

[0057] Return Figure 2 The housing 20 includes a housing main body 21 having an opening at the upper side and a housing cover 23 that covers the opening portion of the housing main body 21. The housing main 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 the left end portions of the front wall portion 82 and the rear wall portion 84; a right wall portion 87 that connects the right end portions 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 single cell accommodation space 25 for accommodating the single cell stack 30.

[0058] Two opening portions 86a that communicate the single cell accommodation space 25 with the outside are provided in the left wall portion 86. One opening portion 86a faces the single cell stack 30 located in the front, and the other opening portion 86a faces the single cell stack 30 located in the rear. When viewed from the stacking direction of the single cells 40, each opening portion 86a is provided at a position facing the central portion of the single cell 40.

[0059] As Figure 1 shown, a pressure release valve 13 that communicates with the single cell accommodation space 25 is installed in each opening portion 86a. When the internal pressure in the single cell accommodation space 25 abnormally rises due to the gas released from the safety valve 44, the pressure release valve 13 opens, and the gas is discharged to the outside of the housing 20 to release the pressure inside the housing 20. The opening portion 86a and the pressure release valve 13 have substantially the same size, and the opening portion 86a is blocked by installing the pressure release valve 13.

[0060] When viewed from the stacking direction, the opening portion 86a and the pressure release valve 13 are provided so as to face the central portion of the single cell 40. Thereby, compared with the case where the opening portion 86a and the pressure release valve 13 are provided at positions deviated from the central portion of the single cell 40 (for example, at a position above the central portion) when viewed from the stacking direction, a decrease in the rigidity of the housing 20 can be suppressed.

[0061] A plate-like spacer 16 is provided between the left wall portion 86 and the end plate 31. By providing the spacer 16, the plurality of single cells 40 and the end plate 31 are clamped and pressed and held in the single cell accommodation space 25 by the left wall portion 86 and the right wall portion 87.

[0062] In addition, as Figure 6 shown, the spacer 16 has a flange portion 16f on the surface facing the left wall portion 86, and the contact surface with the left wall portion 86 is formed to be wide. Since the flange portion 31f is provided, the contact surface of the spacer 16 with the left wall portion 86 becomes wide, and the reaction force from the spacer 16 can be prevented from being locally applied to the left wall portion 86.

[0063] Returning to Figure 2 , in front of and to the left of the front wall portion 82, a bulging portion 22 is formed so as to protrude further forward from the front wall portion 82. A space is formed inside the bulging portion 22, a first opening portion 91 is provided on the front surface, and a second opening portion 92 is also provided on the upper surface. A terminal plate 60 for connecting the extraction conductive member 70 is provided in the internal space of the bulging portion 22, constituting an output terminal accommodation space 27. On the terminal plate 60, the terminal portion (output terminal) of the output conductive member 61 extending from the single cell accommodation space 25 to the output terminal accommodation space 27 is electrically connected to the terminal portion of the extraction conductive member 70 that enters the output terminal accommodation space 27 from the first opening portion 91. The output conductive member 61 includes a positive electrode side bus bar 62 and a negative electrode side bus bar 63, and the positive electrode side bus bar 62 and the negative electrode side bus bar 63 extend from the positive electrode side output terminal and the negative electrode side output terminal of two single cell stacks 30 electrically connected in series, respectively. The extraction conductive member 70 includes a positive electrode side bus bar 72 and a negative electrode side bus bar 73, and the positive electrode side bus bar 72 and the negative electrode side bus bar 73 are connected to, for example, an external positive terminal and a negative terminal, respectively.

[0064] In this way, inside the housing 20, there are provided: a single cell accommodation space 25 that accommodates two single cell stacks 30; and an output terminal accommodation space 27 that is disposed in front of and to the left of the single cell accommodation space 25 and is connected to the extraction conductive member 70. In addition, the number of single cell stacks 30 accommodated in the single cell accommodation space 25 may be one or three or more.

[0065] The height of the region in the front wall portion 82 that separates the single battery accommodation space 25 from the output terminal accommodation space 27 (hereinafter, this portion will be referred to as the partition portion 85) is lower than other regions. The positive-side bus bar 62 and the negative-side bus bar 63 extend from above the partition portion 85 to the output terminal accommodation space 27 and are fixed to the terminal board 60 provided in the output terminal accommodation space 27.

[0066] In addition, as Figure 1 shown, a signal line connector 67 is provided in the output terminal accommodation space 27. The signal line connector 67 is connected to the signal line via a through hole that communicates the single battery accommodation space 25 with the output terminal accommodation space 27.

[0067] As Figure 2 shown, the upper surface of the housing 20 other than the partition portion 85 is provided with a housing cover 23 with a first seal 11 (such as a rubber seal) interposed therebetween. The housing cover 23 is fixed to the upper surface of the housing 20 by welding such as friction stir welding. A second seal 12 (such as a foam seal) is provided in the gap between the partition portion 85 and the housing cover 23, and the single battery accommodation space 25 is sealed from the outside by the first seal 11 and the second seal 12. By sealing the single battery accommodation space 25 from the outside, it is possible to prevent foreign matter from entering the single battery accommodation space 25 and suppress the deterioration of the single battery 40. In addition, it is preferable to provide a seal such as a foam seal also in the gap between the through hole provided in the partition portion 85 and the signal line.

[0068] The battery pack 10 configured in this way does not include auxiliary devices such as a junction box for accommodating contactors, fuses, and an ECU. Therefore, when the battery pack 10 is used alone, the junction box and / or the ECU can be connected to the battery pack 10. In addition, when multiple battery packs 10 are used, the battery packs 10 can also be electrically connected to each other through a distribution box, and the junction box and / or the ECU can be connected to the distribution box. In addition, the junction box and / or the ECU can also be built into the distribution box, and multiple battery packs 10 can be connected to the junction box and / or the ECU in the distribution box.

[0069] Next, with reference to Figure 4 the process of pressing and accommodating a plurality of single batteries 40 in the housing main body 21 will be described in detail. In Figure 4 the (a) to (f), the right figure is a plan view of the battery pack 10, and the left figure is a cross-sectional view taken along line A-A.

[0070] First, as Figure 4As shown in (a) of FIG. 0, a plurality of single cells 40 and an end plate 31 (i.e., a single cell laminate 30) temporarily fixed by a plate clamp 50 are received from above in a single cell receiving space 25 of a housing main body 21. At this time, the end plate 31 faces the left wall portion 86 of the housing main body 21, and the right side surfaces of the plurality of single cells 40 face the right wall portion 87 of the housing main body 21. In this state, the plurality of single cells 40 and the end plate 31 are not held under pressure but are arranged in the housing main body 21 with a clearance.

[0071] Next, as Figure 4 shown in (b) of FIG. 0, a jig T1 is inserted through an opening 86a provided in the left wall portion 86, and the plurality of single cells 40 are pressed against the right wall portion 87 via the end plate 31 by the jig T1. As a result, the right side surfaces of the plurality of single cells 40 come into contact with the right wall portion 87, and the plurality of single cells 40 and the end plate 31 temporarily fixed by the plate clamp 50 are further pressed in the stacking direction.

[0072] Next, as Figure 4 shown in (c) of FIG. 0, while the end plate 31 is being pressed by the jig T1, a temporary spacer T2 is disposed between the end plate 31 and the left wall portion 86. The temporary spacer T2 is a rod-shaped member extending in the vertical direction and is disposed at both ends of the end plate 31. By disposing the temporary spacer T2, after the jig T1 is removed, the plurality of single cells 40 and the end plate 31 are also held under pressure in the housing main body 21, and in addition, a gap G is formed between the end plate 31 and the left wall portion 86.

[0073] Next, as Figure 4 shown in (d) of FIG. 0, after the jig T1 is removed, a spacer 16 is disposed in the gap G. The thickness of the spacer 16 (here, the length in the stacking direction) is set to be equal to or less than the thickness of the temporary spacer T2.

[0074] Next, as Figure 4 shown in (e) of FIG. 0, the jig T1 is inserted again through the opening 86a and the spacer 16 is pressed, thereby increasing the gap G and removing the two temporary spacers T2.

[0075] Finally, as Figure 4 shown in (f) of FIG. 0, the jig T1 is removed. In this state, the plurality of single cells 40 and the end plate 31 are tightly arranged in the stacking direction in the housing main body 21 with the spacer 16 interposed therebetween and are held under pressure. On the contrary, the housing main body 21 receives the reaction force of the plurality of single cells 40 being pressed.

[0076] In addition, after the jig T1 is removed from the opening 86a in (f) of FIG. 0, as Figure 4 shown in Figure 1As shown, a pressure release valve 13 is installed at the opening 86a. In this way, the opening 86a not only serves as an insertion port for the jig T1 used when pressing the plurality of single cells 40 and the end plates 31 against the housing main body 21, but also serves as an installation port for the pressure release valve 13.

[0077] According to the battery pack 10 formed in this way, the plurality of single cells 40 can be held in the housing 20 without modularization, so that the energy density and space efficiency can be improved.

[0078] [Gas exhaust structure]

[0079] In the case where some abnormality occurs in the single cell 40, such as an internal short circuit, the single cell 40 may experience abnormal heat generation, i.e., thermal runaway, and generate high-temperature and high-pressure gas inside the single cell 40. When the pressure of the gas generated inside the single cell 40 rises above a specified value, the safety valve 44 ruptures, and the gas is released to the outside of the single cell 40, i.e., the inside of the housing 20.

[0080] The inside of the housing 20 is sealed to prevent the intrusion of liquid and foreign matter, but in order to discharge the gas to the outside of the housing 20 during thermal runaway, a pressure release valve 13 is provided in the battery pack 10. However, since the single cells 40 are tightly arranged under pressure by the housing 20 via the end plates 31 and the spacers 16, the gap between the single cells 40 and the housing 20 is small, and the inside of the housing 20 is likely to become high pressure when the gas is released from the safety valve 44. If the pressure inside the housing 20 rises, it may cause the housing 20 to rupture. Therefore, in addition to providing the pressure release valve 13, it is preferable to appropriately provide a space for releasing pressure inside the housing 20.

[0081] Therefore, as Figure 5 and Figure 6 shown, a buffer space 47 that communicates with the exhaust passage 46 and functions as a space for releasing pressure, and a plurality of exhaust flow paths 48 that communicate with the buffer space 47 and the pressure release valve 13 are provided between the exhaust passage 46 and the pressure release valve 13.

[0082] The buffer space 47 is provided around the end plate 31. Specifically, the buffer space 47 is provided in a rectangular shape along the entire circumference of the end plate 31. The buffer space 47 communicates with the exhaust passage 46 at the upper part of the end plate 31, and the gas released from the safety valve 44 flows into the buffer space 47 through the exhaust passage 46. The gas flowing into the buffer space 47 circulates along the upper, front, rear, and lower parts of the edge of the end plate 31 and flows toward the plurality of exhaust flow paths 48. In addition, the buffer space 47 may not be provided along the entire circumference of the end plate 31. For example, it may be provided in a substantially inverted U shape by communicating along the upper, front, and rear parts of the edge of the end plate 31.

[0083] Thus, even in the battery pack 10 where multiple single cells 40 are pressurized and closely arranged in the housing 20, a buffer space 47 serving as a space for releasing pressure can be appropriately set, and an increase in pressure inside the housing 20 can be suppressed.

[0084] The buffer space 47 will be described in more detail below. The portions along the upper and lower parts of the end plate 31 in the buffer space 47 are provided between the flange portion 31f of the end plate 31 and the flange portion 16f of the spacer 16. Therefore, the buffer space 47 can be appropriately partitioned and formed by using the flange portion 31f of the end plate 31 and the flange portion 16f of the spacer 16.

[0085] In addition, corresponding to the portion where the temporary spacer T2 is arranged, the portions along the front and rear parts of the end plate 31 in the buffer space 47 are provided between the end plate 31 and the left wall portion 86 of the housing main body 21. Therefore, the portion where the temporary spacer T2 is arranged can also be utilized as a space for releasing pressure.

[0086] A plurality of exhaust flow paths 48 are provided in the spacer 16 to guide the gas flowing into the buffer space 47 to the pressure release valve 13 and discharge the gas from the pressure release valve 13 to the outside of the housing 20. The plurality of exhaust flow paths 48 are formed, for example, by making cutouts on the surface of the spacer 16.

[0087] The plurality of exhaust flow paths 48 extend radially from the pressure release valve 13 toward the buffer space 47. More specifically, as Figure 6 shown, the spacer 16 is provided with a confluence portion 49 where the plurality of exhaust flow paths 48 converge at a position facing the central portion of the single cell 40 when viewed in the stacking direction. The confluence portion 49 is formed by the central portion of the spacer 16 being recessed. The plurality of exhaust flow paths 48 extend radially from the confluence portion 49 toward the buffer space 47. The gas released from the safety valve 44 due to thermal runaway is discharged from the pressure release valve 13 to the outside of the housing 20 via the exhaust passage 46, the buffer space 47, the plurality of exhaust flow paths 48, and the confluence portion 49.

[0088] By the plurality of exhaust flow paths 48 extending radially, the gas can be evenly guided from the buffer space 47 provided around the end plate 31 to the pressure release valve 13. In addition, by the plurality of exhaust flow paths 48 extending radially, the stress applied to the spacer 16 is dispersed. Therefore, even with a structure having the plurality of exhaust flow paths 48, the spacer 16 can sufficiently ensure rigidity without impairing its function of withstanding the reaction force from the single cell 40.

[0089] Each exhaust gas flow path 48 is configured such that in the gas flow direction, the flow path width is wider on the upstream side (the buffer space 47 side) and narrower on the downstream side (the pressure release valve 13 side). Similar to the buffer space 47, the plurality of exhaust gas flow paths 48 also function as spaces for releasing the pressure inside the housing 20. Therefore, by making the flow path width wider on the upstream side, the space for releasing pressure can be increased. On the other hand, the spacer 16 also needs to sufficiently withstand the reaction force from the single cell 40. Therefore, by making the flow path width narrower on the downstream side, a decrease in the rigidity of the spacer 16 caused by the provision of the plurality of exhaust gas flow paths 48 can be suppressed.

[0090] (Second Embodiment)

[0091] Next, the battery pack of the second embodiment will be described. However, for the structures common to the aforementioned first embodiment, the description of the first embodiment may sometimes be referred to by using the same reference numerals.

[0092] In the battery pack of the first embodiment, it is configured to press a plurality of single cells 40 using the spacer 16, but as Figure 7 shown, the battery pack 10 of the second embodiment includes a pressure plate 28 provided on the housing main body 21 instead of the spacer 16, and the pressure plate 28 is used to press a plurality of single cells 40.

[0093] An opening 86b for communicating the single cell accommodation space 25 with the outside is provided in the left wall portion 86 of the housing 20. The pressure plate 28 is mounted on the left wall portion 86 so as to cover the opening 86b via a seal 17 (e.g., a rubber seal), and forms a part of the left wall portion 86 of the housing main body 21. The fixing of the pressure plate 28 to the left wall portion 86 can be a fixing based on welding such as friction stir welding or a bolt fixing. Similar to the first embodiment, in the battery pack 10 of the second embodiment, a plurality of single cells 40 can be held in the housing 20 without modularization, so that the energy density and space efficiency can be improved.

[0094] The opening 86b has a substantially rectangular shape and is larger than the opening 86a of the first embodiment. On the other hand, the opening 86b is smaller than the flange portion 31f of the end plate 31. In this way, a decrease in the rigidity of the housing 20 due to the enlargement of the opening 86b can be suppressed.

[0095] As Figure 8 shown, the pressure plate 28 has a flange portion 281 opposed to the edge portion of the opening 86b, a convex portion 282 inserted into the inside of the housing 20 from the opening 86b and pressing the end plate 31, and two openings 283 for mounting the pressure release valve 13. In the opening 86b, a step is formed at the outer side position of the housing 20, and the pressure plate 28 is fixed to the left wall portion 86 with the flange portion 281 fitted into the step.

[0096] By fixing the pressing plate 28 to the left wall portion 86, the convex portion 282 of the pressing plate 28 contacts the end plate 31 of each single cell laminate 30. The convex portion 282 of the pressing plate 28 presses the end plate 31, whereby the plurality of single cells 40 temporarily fixed by the plate clamp 50 are further pressed in the stacking direction and held in the housing 20.

[0097] As Figure 8 and Figure 9 shown, similar to the first embodiment, in the second embodiment, a buffer space 47 is provided around the end plate 31. On the other hand, the pressure release valve 13 and a plurality of exhaust flow paths 48 are provided in the pressing plate 28.

[0098] The buffer space 47 is provided around the flange portion 31f of the end plate 31 and the convex portion 282 of the pressing plate 28, and is formed by partitioning with the end plate 31, the pressing plate 28, and the housing 20. In the present embodiment, the buffer space 47 is also provided along the entire circumference of the flange portion 31f.

[0099] Two pressure release valves 13 are installed to block two openings 283 provided in the pressing plate 28. When viewed from the stacking direction, the pressure release valve 13 and the opening 283 are arranged so as to face the central portion of the single cell 40. Thus, compared with the case where the pressure release valve 13 and the opening 283 are arranged at positions deviated from the central portion of the single cell 40 when viewed from the stacking direction, for example, a reduction in the rigidity of the pressing plate 28, that is, the rigidity of the housing 20 can be suppressed.

[0100] A plurality of exhaust flow paths 48 are provided in the convex portion 282 of the pressing plate 28 to guide the gas flowing into the buffer space 47 to the pressure release valve 13 and discharge the gas from the pressure release valve 13 to the outside of the housing 20. The plurality of exhaust flow paths 48 extend radially from the pressure release valve 13 toward the buffer space 47. The plurality of exhaust flow paths 48 provided in the pressing plate 28 also have the same structure as the plurality of exhaust flow paths 48 provided in the spacer 16.

[0101] In this way, even in the battery pack 10 in which a plurality of single cells 40 are pressed and closely arranged in the housing 20, the buffer space 47 as a space for releasing pressure can be appropriately provided, and an increase in the pressure inside the housing 20 can be suppressed. Furthermore, through the plurality of exhaust flow paths 48 provided in the pressing plate 28, the gas can be appropriately guided to the pressure release valve 13 and discharged to the outside of the housing.

[0102] As described above, each embodiment of the present invention has been described with reference to the accompanying drawings. However, the present invention is of course not limited to this embodiment. Those skilled in the art should understand that various variations or modifications can obviously be conceived within the scope described in the technical solution, and these variations or modifications also of course belong to the technical scope of the present invention. In addition, within the scope not departing from the gist of the invention, the constituent elements in the above embodiments can be arbitrarily combined.

[0103] For example, in the above embodiment, the end plate 31 is only disposed on one side (the left side in the embodiment) of the plurality of single cells 40 in the stacking direction, but it can also be disposed on both sides of the plurality of single cells 40 in the stacking direction.

[0104] At least the following matters are described in this specification. In the parentheses, the corresponding constituent elements, etc. in the above embodiment are shown as an example, but are not limited thereto.

[0105] (1) A battery pack (battery pack 10), comprising:

[0106] A plurality of stacked single cells (single cell 40) having a safety valve (safety valve 44);

[0107] An end plate (end plate 31) provided at an end of the single cells in the stacking direction;

[0108] An exhaust passage (exhaust passage 46) connecting the safety valves of the respective single cells and extending in the stacking direction;

[0109] A housing (housing 20) accommodating the single cells, the end plate, and the exhaust passage; and

[0110] A pressure release valve (pressure release valve 13) installed on a surface of the housing facing the end plate, capable of discharging the gas released from the safety valve to the outside of the housing, wherein,

[0111] Between the exhaust passage and the pressure release valve, there is provided:

[0112] A space (buffer space 47) formed around the end plate and communicating with the exhaust passage; and

[0113] A plurality of flow paths (exhaust flow paths 48) connecting the space and the pressure release valve.

[0114] According to (1), even when gas is released from the safety valve of the single cell due to thermal runaway, the pressure can be released to the space formed around the end plate, so that the pressure rise inside the housing can be suppressed. In addition, through the plurality of flow paths connecting this space and the pressure release valve, the gas released from the single cell can be appropriately guided to the pressure release valve and discharged to the outside of the housing.

[0115] (2)The battery pack according to (1), wherein,

[0116] The plurality of flow paths extend radially from the pressure release valve toward the space.

[0117] According to (2), the gas released from the safety valve can be evenly guided from the space around the end plate to the pressure release valve.

[0118] (3)The battery pack according to (1) or (2), wherein,

[0119] The end plate is provided on one end side in the stacking direction of the single cell,

[0120] The other end side in the stacking direction of the single cell abuts against the housing,

[0121] The single cell is pressed from the one end side to the other end side and housed in the housing.

[0122] According to (3), even in a battery pack in which a plurality of single cells are pressed and tightly housed in a housing, the pressure can be released to the space formed around the end plate, and the pressure rise in the housing can be suppressed.

[0123] (4)The battery pack according to (3), wherein,

[0124] The battery pack further includes a spacer (spacer 16), which is provided between the end plate and the housing in the stacking direction, and presses the single cell via the end plate,

[0125] The plurality of flow paths are provided in the spacer.

[0126] According to (4), the spacer that presses the single cell can have a function of guiding the gas to the pressure release valve.

[0127] (5)The battery pack according to (4), wherein,

[0128] The end plate has a flange portion (flange portion 31f) on the surface facing the single cell,

[0129] The spacer has a flange portion (flange portion 16f) on the surface facing the housing,

[0130] At least a part of the space is provided between the flange portion of the end plate and the flange portion of the spacer.

[0131] According to (5), by means of the flange portions of the end plate and the spacer, local stress acting on the single cell and the housing can be suppressed when pressing the single cell. Moreover, a space for releasing pressure can be appropriately partitioned by the flange portions.

[0132] (6) The battery pack according to (3), wherein

[0133] the housing has:

[0134] an opening portion (opening portion 86b) provided on a surface opposed to the end plate; and

[0135] a pressing plate (pressing plate 28) inserted into the opening portion and pressing the single cell via the end plate,

[0136] the pressure release valve and the plurality of flow paths are provided on the pressing plate.

[0137] According to (6), the pressing plate for pressing the single cell can have a function of guiding gas to the pressure release valve.

[0138] (7) The battery pack according to (6), wherein

[0139] the pressing plate has:

[0140] a flange portion (flange portion 281) opposed to an edge portion of the opening portion; and

[0141] a convex portion (convex portion 282) protruding from the opening portion toward the inside of the housing and pressing the single cell via the end plate,

[0142] the plurality of flow paths are provided on the convex portion.

[0143] According to (7), the convex portion of the pressing plate for pressing the single cell can have a function of guiding gas to the pressure release valve.

[0144] (8) The battery pack according to (7), wherein

[0145] the end plate has a flange portion (flange portion 31f) on a surface opposed to the single cell,

[0146] the opening portion of the housing is smaller than the flange portion of the end plate.

[0147] According to (8), by means of the flange portion of the end plate, local stress acting on the single cell can be suppressed when pressing the single cell. Moreover, by making the opening portion of the housing smaller than the flange portion of the end plate, an increase in the opening portion and a reduction in the rigidity of the housing can be suppressed.

[0148] (9) The battery pack according to (8), wherein

[0149] The space is provided around the flange portion of the end plate and the convex portion of the pressing plate.

[0150] According to (9), the space for releasing pressure can be appropriately divided and formed by the flange portion of the end plate and the convex portion of the pressing plate.

[0151] (10) The battery pack according to any one of (1) to (9), wherein

[0152] The pressure release valve is provided in the housing so as to face the central portion of the single cell when viewed from the stacking direction.

[0153] According to (10), a reduction in the rigidity of the housing can be suppressed.

Claims

1. A battery pack comprising: A plurality of stacked single cells having a safety valve; an end plate disposed at an end portion of the single cells in a stacking direction; an exhaust passage connected to the safety valve of each single cell and extending along the stacking direction; a housing that accommodates the single cell, the end plate, and the exhaust passage; and A pressure relief valve is mounted on a surface of the housing that is opposite to the end plate and is capable of discharging the gas released from the safety valve to the outside of the housing, wherein: Between the exhaust passage and the pressure release valve is provided: a space formed around the end plate and communicating with the exhaust passage; and A plurality of flow paths connect the space to the pressure release valve.

2. The battery pack according to claim 1, wherein: The plurality of flow paths radially extend from the pressure release valve toward the space.

3. The battery pack according to claim 1, wherein: The end plate is provided at one end side of the stacking direction of the single cells. The other end side of the single cell in the stacking direction is in contact with the casing, The single cell is pressed from the one end side toward the other end side and is accommodated in the case.

4. The battery pack according to claim 3, wherein: The battery pack further includes a spacer that is provided between the end plate and the case in the stacking direction and presses the single cell via the end plate. The plurality of flow paths are provided in the spacer.

5. The battery pack according to claim 4, wherein: The end plate has a flange portion on a surface facing the single cell. The spacer has a flange portion on a surface facing the housing. At least a portion of the space is provided between the flange portion of the end plate and the flange portion of the spacer.

6. The battery pack according to claim 3, wherein: The housing has: an opening portion provided on a surface opposite to the end plate; and a pressurizing plate inserted into the opening to press the battery cell via the end plate; The pressure release valve and the plurality of flow paths are provided on the pressurizing plate.

7. The battery pack according to claim 6, wherein: The pressure plate has: a flange portion that is opposed to an edge of the opening portion; and a convex portion that protrudes from the opening toward the inner side of the housing and presses the single cell via the end plate, The plurality of flow paths are provided in the convex portion.

8. The battery pack according to claim 7, wherein: The end plate has a flange portion on a surface facing the single cell. The opening portion of the housing is smaller than the flange portion of the end plate.

9. The battery pack according to claim 8, wherein: The space is provided around the flange portion of the end plate and the convex portion of the pressure plate.

10. The battery pack according to any one of claims 1 to 9, wherein: The pressure release valve is provided on the case so as to face a center portion of the unit cell when viewed from the stacking direction.

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