Battery pack

Abstract

To provide a battery pack that can suppress increase of a pressure inside a case caused by gas generated during thermal runaway of battery cells, and appropriately exhaust the gas to the outside of the case.SOLUTION: A battery pack 10 comprises: a plurality of laminated battery cells 40 each having a safety valve 44; an end plate 31 provided at an end in the lamination direction of the battery cells 40; an exhaust duct 46 that connects the safety valves 44 of the battery cells 40 with each other; a case 20 that accommodates the battery cells, end plate, and exhaust duct; and a pressure release valve 13 that is attached to the surface of the case 20 facing the end plate 31, and can exhaust the gas discharged from the safety valves 44 to the outside of the case 20. Buffer spaces 47 formed on the periphery of the end plate 31 and communicating with the exhaust duct 46, and a plurality of exhaust passages 48 communicating the buffer spaces 47 and the pressure release valve 13 with each other, are provided between the exhaust duct 46 and the pressure release valve 13.SELECTED DRAWING: Figure 5

Description

[Technical Field]

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

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

[0003] As vehicles are increasingly equipped with electric drive sources, they are equipped with batteries that supply power to motors and other devices. Batteries are typically made up of multiple stacked battery cells. Each battery cell is equipped with a safety valve that releases high-temperature, high-pressure gas generated inside the battery cell due to an abnormality or other reason.

[0004] For example, Patent Document 1 describes a battery module in which unit cells, each with a safety valve in its case, are connected in a row, an exhaust duct is provided by a hood covering the row of safety valves, an end plate is placed on each of the outermost unit cells in the row, and the two end plates sandwich and secure the unit cells. One of the end plates is provided with an inlet that communicates with the exhaust duct, and an exhaust port that communicates with the inlet. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-79510 Summary of the Invention [Problem to be solved by the invention]

[0006] 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 exhausted from the exhaust port in the end plate, filling the case. In order to reduce the impact on the outside caused by the increase in pressure inside the case, a configuration is desired that can appropriately exhaust the gas inside the case to the outside while suppressing the increase in pressure inside the case.

[0007] The present invention provides a battery pack that can suppress a pressure increase inside the case due to gas generated during thermal runaway of a battery cell and can appropriately vent the gas to the outside of the case, thereby contributing to improved energy efficiency. [Means for solving the problem]

[0008] The present invention provides a plurality of stacked battery cells each having a safety valve; end plates provided at the ends of the battery cells in the stacking direction; an exhaust duct that connects the safety valves of each battery cell and extends in the stacking direction; a case that houses the battery cells, the end plates, and the exhaust duct; a pressure release valve attached to a surface of the case facing the end plate, the pressure release valve being capable of venting gas released from the safety valve to the outside of the case, Between the exhaust duct and the pressure relief valve, a space formed around the end plate and communicating with the exhaust duct; a plurality of flow paths communicating the space with the pressure release valve; And, the end plate is provided on one end side of the battery cell in the stacking direction, the other end of the battery cell in the stacking direction abuts against the case, The battery cell is housed in the case while being pressed from the one end side toward the other end side. . [Effects of the Invention]

[0009] According to the present invention, it is possible to suppress a pressure increase inside the case due to gas generated during thermal runaway of a battery cell, and to properly exhaust the gas to the outside of the case. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is an external perspective view of a battery pack 10 according to a first embodiment. [Figure 2] 1 is an exploded perspective view of a battery pack 10 according to a first embodiment. [Figure 3] FIG. 2 is an exploded perspective view of the cell stack 30. [Figure 4] 10A and 10B are diagrams showing a process of pressurizing a plurality of battery cells 40 and accommodating them in a case body 21. FIG. [Figure 5] 10 is a diagram showing the flow of gas (broken arrow) guided to the pressure release valve 13. FIG. [Figure 6] FIG. 2 is a partial cross-sectional perspective view of the vicinity of the pressure release valve 13. [Figure 7] FIG. 10 is an exploded perspective view of a battery pack 10 according to a second embodiment. [Figure 8] 10 is a cross-sectional view of a pressure plate 28 pressing against a plurality of battery cells 40 and an end plate 31. FIG. [Figure 9] 10 is a diagram showing a buffer space 47 formed around the end plate 31 and the flow of gas (indicated by dashed arrows) flowing through a plurality of exhaust flow paths 48 provided in the pressure plate 28. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the battery pack of the present invention will be described with reference to the accompanying drawings. For convenience, the following description will be made using a coordinate system consisting of mutually orthogonal longitudinal, lateral, and vertical directions. In the drawings, the front is indicated as Fr, the rear as Rr, the left as L, the right as R, the top as U, and the bottom as D. However, these directions are unrelated to the orientation of the battery pack when mounted on a device. For example, when the battery pack is mounted on a vehicle, the top and bottom of the battery pack may face the direction of travel of the vehicle or the width direction of the vehicle.

[0012] (First embodiment) [Battery pack] First, a battery pack according to a first embodiment will be described. As shown in FIGS. 1 and 2, the battery pack 10 includes two cell stacks 30 arranged side by side in the front-to-rear direction inside a box-shaped case 20. As shown in FIG. 3, the cell stack 30 includes a plurality of rectangular battery cells 40 stacked in the left-to-right direction and an end plate 31 arranged on one side in the left-to-right direction (the left side in this embodiment), which are temporarily fixed in place with a predetermined pressure using a binder 50. Separators (not shown) may be disposed 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-to-rear direction. The lower restraint portion 51 and the pair of side restraint portions 53 are integrally formed. It should be noted that another end plate, separator, etc. may be arranged on the other left-right side of the cell stack 30 (the right side in this embodiment) so that the battery cells 40 on the other side do not come into direct contact with the case 20. Furthermore, the cell stack 30 does not have to be configured so that the multiple battery cells 40 are restrained by the binder 50; that is, the multiple battery cells 40 may be configured so that they are directly stacked inside the case 20.

[0013] The end plate 31 has flange portions 31f at its lower and upper ends, and the flange portions 31f are restrained by the lower restraint portion 51 and the upper restraint portion 52, thereby fixing the end plate 31 to the multiple battery cells 40. The provision of the flange portions 31f increases the contact surface between the end plate 31 and the battery cells 40, making it possible to prevent the reaction force from the end plate 31 from being applied locally to the battery cells 40.

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

[0015] The safety valve 44 is a burst valve that prevents the outer can from bursting if the internal pressure of the battery cell 40 increases abnormally. If 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 in the center of the front-to-rear direction of the battery cell 40, multiple 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 exhaust ducts 46 that connect the safety valves 44 of multiple battery cells 40 and through which gas released from the safety valves 44 flows. For example, the exhaust ducts 46 are configured by hoods that cover the safety valves 44. The exhaust ducts 46 extend in the direction in which the safety valves 44 are lined up, i.e., in the stacking direction of the battery cells 40, and guide the gas toward the pressure release valve 13, which will be described later.

[0017] 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 the left ends of the front wall portion 82 and the rear wall portion 84, a right wall portion 87 that connects the 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 forms a cell accommodating space 25 that accommodates the cell stack 30.

[0018] The left wall 86 has two openings 86a that connect the cell accommodating space 25 to the outside. One opening 86a faces the cell stack 30 located in the front, and the other opening 86a faces the cell stack 30 located in the rear. Each opening 86a is located in a position facing the center of a battery cell 40 when viewed from the stacking direction of the battery cells 40.

[0019] 1, a pressure release valve 13 communicating with the cell accommodating space 25 is attached to each opening 86a. The pressure release valve 13 opens when the internal pressure of the cell accommodating space 25 increases abnormally due to gas released from the safety valve 44, and discharges the gas to the outside of the case 20 to release the pressure inside the case 20. The opening 86a and the pressure release valve 13 have approximately the same size, and the opening 86a is closed by attaching the pressure release valve 13.

[0020] When viewed from the stacking direction, the opening 86a and the pressure release valve 13 are provided so as to face the center of the battery cell 40. This makes it possible to prevent a decrease in the rigidity of the case 20 compared to when the opening 86a and the pressure release valve 13 are provided in a position offset from the center of the battery cell 40 (for example, in a position above the center) when viewed from the stacking direction.

[0021] A plate-shaped spacer 16 is provided between the left wall portion 86 and the end plate 31. By providing the spacer 16, the multiple battery cells 40 and the end plate 31 are sandwiched between the left wall portion 86 and the right wall portion 87 in the cell accommodating space 25 and are held in place under pressure.

[0022] 6, the spacer 16 has a flange 16f on the surface facing the left wall 86, and the abutment surface with the left wall 86 is configured to be wide. The provision of the flange 31f widens the abutment surface between the spacer 16 and the left wall 86, and it is possible to suppress the reaction force from the spacer 16 from being locally applied to the left wall 86.

[0023] Returning to FIG. 2 , a bulge 22 is formed in front of and to the left of the front wall 82, protruding further forward from the front wall 82. A space is formed inside the bulge 22, with a first opening 91 provided on the front surface and a second opening 92 provided on the top surface. A terminal block 60 to which the output conductive member 70 is connected is provided in the internal space of the bulge 22, forming the output terminal accommodating space 27. The terminal block 60 electrically connects a terminal portion (output terminal) of the output conductive member 61 extending from the cell accommodating space 25 into the output terminal accommodating space 27 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, respectively, of the two cell stacks 30 electrically connected in series. 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.

[0024] Thus, the case 20 is provided inside with a cell accommodating space 25 that accommodates 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 extraction 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.

[0025] In the front wall portion 82, an area separating the cell accommodating space 25 and the output terminal accommodating space 27 (hereinafter, this portion will be referred to as a partition portion 85) is lower in height than other areas. The positive side bus bar 62 and the negative side bus bar 63 extend from above the partition portion 85 into the output terminal accommodating space 27 and are fixed to a terminal block 60 provided in the output terminal accommodating space 27.

[0026] 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.

[0027] As shown in FIG. 2, a case cover 23 is attached to the top surface of the case 20, excluding the partition wall portion 85, via a first sealant 11 (e.g., a rubber seal). The case cover 23 is fixed to the top surface of the case 20 by welding, for example, friction stir welding. A second sealant 12 (e.g., a foam sealant) is provided in the gap between the partition wall portion 85 and the case cover 23, and the cell accommodating space 25 is sealed from the outside by the first sealant 11 and the second sealant 12. Sealing the cell accommodating space 25 from the outside prevents foreign matter from entering the cell accommodating space 25, thereby suppressing deterioration of the battery cells 40. It is preferable that a sealant, such as a foam sealant, is also provided in the gap between the signal line and the through hole provided in the partition wall portion 85.

[0028] The battery pack 10 configured in this manner does not include auxiliary devices such as a junction box that houses contactors, fuses, etc., or an ECU. Therefore, when using a single battery pack 10, a junction box and / or an ECU may be connected to the battery pack 10. When using multiple battery packs 10, the battery packs 10 may be electrically connected to each other using a connection box, and the junction box and / or an ECU may be connected to the connection box. Alternatively, the junction box and / or an ECU may be built into the connection box, and multiple battery packs 10 may be connected to the junction box and / or ECU within the connection box.

[0029] Next, the process of pressurizing and accommodating multiple battery cells 40 in the case body 21 will be described in detail with reference to Fig. 4. In (a) to (f) of Fig. 4, the right-hand figures are top views of the battery pack 10, and the left-hand figures are cross-sectional views taken along line AA.

[0030] First, as shown in Figure 4(a), the multiple battery cells 40 and end plate 31 (i.e., the cell stack 30) temporarily fixed with binders 50 are placed from above into the cell storage space 25 of the case body 21. At this time, the end plate 31 faces the left wall portion 86 of the case body 21, and the right side surfaces of the multiple battery cells 40 face the right wall portion 87 of the case body 21. In this state, the multiple battery cells 40 and end plate 31 are not held under pressure by the case body 21, and are arranged with some play.

[0031] Next, as shown in Figure 4(b), a jig T1 is inserted through the opening 86a provided in the left wall portion 86, and the jig T1 presses the multiple battery cells 40 toward the right wall portion 87 via the end plate 31. As a result, the right side surfaces of the multiple battery cells 40 come into contact with the right wall portion 87, and the multiple battery cells 40 and the end plate 31 that are temporarily fixed by the binder 50 are further compressed in the stacking direction.

[0032] Next, as shown in Figure 4(c), while the end plate 31 is being pressed by the jig T1, temporary spacers T2 are placed between the end plate 31 and the left wall portion 86. The temporary spacers T2 are rod-shaped members that extend in the vertical direction and are placed on both ends of the end plate 31. By placing the temporary spacers T2, the multiple battery cells 40 and the end plate 31 are held under pressure by the case main body 21 even after the jig T1 is removed, and a gap G is formed between the end plate 31 and the left wall portion 86.

[0033] Next, as shown in Fig. 4(d), after removing the jig T1, a spacer 16 is placed 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.

[0034] Next, as shown in FIG. 4(e), the jig T1 is inserted again through the opening 86a to press the spacer 16, thereby enlarging the gap G and removing the two temporary spacers T2.

[0035] Finally, as shown in Figure 4(f), the jig T1 is removed. In this state, the multiple battery cells 40 and end plates 31 are closely arranged in the stacking direction in the case body 21 via the spacers 16, and are held under pressure. Conversely, the case body 21 receives the reaction force of the multiple pressed battery cells 40.

[0036] After the jig T1 is removed from the opening 86a in Figure 4(f), the pressure release valve 13 is attached to the opening 86a as shown in Figure 1. In this way, the opening 86a not only serves as an insertion port for the jig T1 used to press the multiple battery cells 40 and end plate 31 against the case body 21, but also as an attachment port for the pressure release valve 13.

[0037] According to the battery pack 10 formed in this manner, a plurality of battery cells 40 can be held within the case 20 without being modularized, thereby improving energy density and space efficiency.

[0038] [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.

[0039] The inside of the case 20 is sealed to prevent the intrusion of liquids and foreign objects, but the battery pack 10 is provided with a pressure relief valve 13 to vent gas to the outside of the case 20 in the event of thermal runaway. However, because the battery cells 40 are tightly arranged and pressurized by the case 20 via the end plates 31 and spacers 16, there is a small gap between the battery cells 40 and the case 20, and the inside of the case 20 is likely to become highly pressurized when gas is released from the safety valve 44. If the pressure inside the case 20 increases, it could lead to the case 20 bursting, so in addition to providing the pressure relief valve 13, it is preferable to provide an appropriate space inside the case 20 to release pressure.

[0040] Therefore, as shown in Figures 5 and 6, a buffer space 47 that communicates with the exhaust duct 46 and functions as a space for releasing pressure, and multiple exhaust flow paths 48 that communicate with the buffer space 47 and the pressure release valve 13 are provided between the exhaust duct 46 and the pressure release valve 13.

[0041] The buffer space 47 is provided around the end plate 31. Specifically, the buffer space 47 is rectangular and extends along the entire periphery of the end plate 31. The buffer space 47 communicates with the exhaust duct 46 at the top of the end plate 31, and gas released from the safety valve 44 flows into the buffer space 47 through the exhaust duct 46. The gas that flows into the buffer space 47 flows along the upper, front, rear, and lower edges of the end plate 31 and into multiple exhaust flow paths 48. The buffer space 47 does not have to be provided along the entire periphery of the end plate 31. For example, the buffer space 47 may be configured to communicate with the upper, front, and rear edges of the end plate 31 and have a generally inverted U-shape.

[0042] In this way, even in a battery pack 10 in which multiple battery cells 40 are pressurized and densely arranged in a case 20, a buffer space 47 can be appropriately provided as a space for releasing pressure, thereby suppressing pressure increases within the case 20.

[0043] The buffer space 47 will be described in more detail. The portions of the buffer space 47 along the upper and lower portions of the end plate 31 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 defined and formed by utilizing the flange portion 31f of the end plate 31 and the flange portion 16f of the spacer 16.

[0044] Furthermore, the portions of the buffer space 47 along the front and rear of the end plate 31 correspond to the portions where the temporary spacer T2 was disposed, and are provided between the end plate 31 and the left wall portion 86 of the case body 21. Therefore, the portions where the temporary spacer T2 was disposed can also be used as spaces for releasing pressure.

[0045] A plurality of exhaust flow paths 48 are provided in the spacer 16, and guide the gas that has flowed into the buffer space 47 to the pressure release valve 13, and exhaust the gas from the pressure release valve 13 to the outside of the case 20. The plurality of exhaust flow paths 48 are formed by, for example, cutting out notches in the surface of the spacer 16.

[0046] The multiple exhaust flow paths 48 extend radially from the pressure release valve 13 toward the buffer space 47. More specifically, as shown in FIG. 6 , the spacer 16 is provided with a junction 49 where the multiple exhaust flow paths 48 join, at a position facing the center of the battery cells 40 when viewed from the stacking direction. The junction 49 is formed by recessing the center of the spacer 16. The multiple exhaust flow paths 48 extend radially from the junction 49 toward the buffer space 47. Gas released from the safety valve 44 due to thermal runaway is exhausted from the pressure release valve 13 to the outside of the case 20 via the exhaust duct 46, the buffer space 47, the multiple exhaust flow paths 48, and the junction 49.

[0047] The multiple exhaust flow paths 48 extending radially allow gas to be guided in a balanced manner from the buffer space 47 provided around the end plate 31 to the pressure release valve 13. Furthermore, the multiple exhaust flow paths 48 extending radially distribute the stress applied to the spacer 16, so even though the spacer 16 has multiple exhaust flow paths 48, it can ensure sufficient rigidity without compromising its ability to withstand the reaction force from the battery cells 40.

[0048] Each exhaust flow path 48 is configured so that the flow path width is wide on the upstream side (toward the buffer space 47) in the gas flow direction and narrow on the downstream side (toward the pressure release valve 13). Similar to the buffer space 47, the multiple exhaust flow paths 48 also function as spaces for releasing pressure inside the case 20, so by widening the flow path width on the upstream side, the space for releasing pressure can be made larger. On the other hand, because the spacer 16 must also be able to adequately withstand the reaction force from the battery cells 40, by narrowing the flow path width on the downstream side, it is possible to prevent a decrease in the rigidity of the spacer 16 due to the provision of multiple exhaust flow paths 48.

[0049] (Second embodiment) Next, a battery pack according to a second embodiment will be described. However, the same reference numerals will be used for components common to the first embodiment, and the description of the first embodiment may be used.

[0050] In the battery pack of the first embodiment, the spacers 16 are used to apply pressure to the multiple battery cells 40. However, as shown in FIG. 7, the battery pack 10 of the second embodiment includes a pressure plate 28 provided on the case body 21 instead of the spacers 16, and applies pressure to the multiple battery cells 40 using the pressure plate 28.

[0051] An opening 86b that connects the cell accommodating space 25 to the outside is provided in the left wall 86 of the case 20. The pressure plate 28 is attached to the left wall 86 so as to cover the opening 86b via a sealant 17 (e.g., a rubber seal), and constitutes a part of the left wall 86 of the case main body 21. The pressure plate 28 may be fixed to the left wall 86 by welding such as friction stir welding, or by bolting. As in the first embodiment, the battery pack 10 of the second embodiment can also hold multiple battery cells 40 within the case 20 without modularizing them, thereby improving energy density and space efficiency.

[0052] 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, the increase in the size of the opening 86b can prevent the rigidity of the case 20 from decreasing.

[0053] 8, the pressure plate 28 has a flange portion 281 facing the edge of the opening 86b, a protrusion 282 that is inserted into the inside of the case 20 from the opening 86b and presses the end plate 31, and two openings 283 to which the pressure release valves 13 are attached. A step is formed in the opening 86b at a position outside the case 20, and the pressure plate 28 is fixed to the left wall portion 86 so that the flange portion 281 fits into the step.

[0054] By fixing the pressure plate 28 to the left wall portion 86, the protrusions 282 of the pressure plate 28 come into contact with the end plates 31 of each cell stack 30. The protrusions 282 of the pressure plate 28 press against the end plates 31, so that the multiple battery cells 40 temporarily fixed in place by the binder 50 are further compressed in the stacking direction and held within the case 20.

[0055] As shown in Figures 8 and 9, in the second embodiment, a buffer space 47 is provided around the end plate 31 as in the first embodiment, while the pressure release valve 13 and multiple exhaust flow paths 48 are provided in the pressure plate 28.

[0056] The buffer space 47 is provided around the flange portion 31f of the end plate 31 and the protrusion 282 of the pressure plate 28, and is defined by the end plate 31, the pressure plate 28, and the case 20. In this embodiment, the buffer space 47 is also provided along the entire circumference of the flange portion 31f.

[0057] Two pressure release valves 13 are attached to close two openings 283 provided in the pressure plate 28. The pressure release valves 13 and the openings 283 are provided to face the center of the battery cell 40 when viewed from the stacking direction. This makes it possible to prevent a decrease in the rigidity of the pressure plate 28, i.e., the rigidity of the case 20, compared to when the pressure release valves 13 and the openings 283 are positioned away from the center of the battery cell 40 when viewed from the stacking direction, for example.

[0058] The plurality of exhaust flow paths 48 are provided in the protrusion 282 of the pressure plate 28, and guide the gas that has flowed into the buffer space 47 to the pressure release valve 13, and exhaust the gas from the pressure release valve 13 to the outside of the case 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 pressure plate 28 have the same configuration as the plurality of exhaust flow paths 48 provided in the spacer 16.

[0059] In this way, even in a battery pack 10 in which multiple pressurized battery cells 40 are closely arranged in the case 20, it is possible to appropriately provide a buffer space 47 as a space for releasing pressure, thereby suppressing a rise in pressure inside the case 20. Furthermore, gas can be appropriately guided to the pressure release valve 13 through multiple exhaust flow paths 48 provided in the pressure plate 28 and discharged to the outside of the case.

[0060] Although the embodiments of the present invention have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such embodiments. It is clear that a person skilled in the art can conceive of various modifications or alterations within the scope of the claims, and it is understood that these also naturally fall within the technical scope of the present invention. Furthermore, the components of the above embodiments may be combined in any manner without departing from the spirit of the invention.

[0061] For example, in the above-described embodiment, the end plate 31 is arranged on only one side (the left side in this embodiment) of the plurality of battery cells 40 in the stacking direction, but it may also be arranged on both sides of the plurality of battery cells 40 in the stacking direction.

[0062] This specification describes at least the following: In parentheses, components corresponding to those in the above-described embodiments are shown as examples, but the present invention is not limited to these.

[0063] (1) A plurality of stacked battery cells (battery cells 40) each having a safety valve (safety valve 44); end plates (end plates 31) provided at the ends of the battery cells in the stacking direction; an exhaust duct (exhaust duct 46) that connects the safety valves of each battery cell and extends in the stacking direction; a case (case 20) that houses the battery cells, the end plates, and the exhaust duct; a pressure release valve (pressure release valve 13) attached to a surface of the case facing the end plate and capable of venting gas released from the safety valve to the outside of the case, Between the exhaust duct and the pressure relief valve, a space (buffer space 47) formed around the end plate and communicating with the exhaust duct; a plurality of flow paths (exhaust flow paths 48) communicating the space with the pressure release valve are provided. Battery pack.

[0064] According to (1), even if gas is released from the safety valve of a battery cell due to thermal runaway, the pressure can be released into the space formed around the end plate, thereby suppressing pressure buildup inside the case. Furthermore, multiple flow paths connecting this space with the pressure release valve allow the gas released from the battery cell to be appropriately guided to the pressure release valve and vented to the outside of the case.

[0065] (2) The battery pack according to (1), The plurality of flow paths extend radially from the pressure release valve toward the space. Battery pack.

[0066] According to (2), the gas released from the safety valve can be guided in a balanced manner from the space around the end plate to the pressure release valve.

[0067] (3) The battery pack according to (1) or (2), the end plate is provided on one end side of the battery cell in the stacking direction, the other end of the battery cell in the stacking direction abuts against the case, The battery cell is housed in the case while being pressed from the one end side toward the other end side. Battery pack.

[0068] According to (3), even in a battery pack in which multiple battery cells are compressed and tightly packed inside a case, the pressure can be released into the space formed around the end plate, thereby suppressing the increase in pressure inside the case.

[0069] (4) The battery pack according to (3), the battery pack further includes a spacer (spacer 16) that is provided between the end plate and the case in the stacking direction and presses the battery cell via the end plate; The plurality of flow paths are provided in the spacer. Battery pack.

[0070] According to (4), the spacer that presses the battery cell can be given the function of directing gas to the pressure release valve.

[0071] (5) The battery pack according to (4), The end plate has a flange portion (flange portion 31f) on the surface facing the battery cell, The spacer has a flange portion (flange portion 16f) on a surface facing the case, At least a portion of the space is provided between the flange portion of the end plate and the flange portion of the spacer. Battery pack.

[0072] According to (5), the flanges of the end plates and the spacer can prevent localized stress from acting on the battery cell and the case when the battery cell is pressed. Furthermore, the flanges can be used to appropriately define a space for releasing pressure.

[0073] (6) The battery pack according to (3), The case is an opening (opening 86b) provided on a surface facing the end plate; a pressure plate (pressure plate 28) that is inserted into the opening and presses the battery cell via the end plate; the pressure release valve and the plurality of flow paths are provided in the pressure plate. Battery pack.

[0074] According to (6), the pressure plate that presses the battery cell can be given the function of directing gas to the pressure release valve.

[0075] (7) The battery pack according to (6), The pressure plate is a flange portion (flange portion 281) facing the edge portion of the opening; a protrusion (protrusion 282) that protrudes from the opening toward the inside of the case and presses the battery cell via the end plate, The plurality of flow paths are provided in the convex portion. Battery pack.

[0076] According to (7), the protrusions of the pressure plate that press against the battery cells can be given the function of directing gas to the pressure release valve.

[0077] (8) The battery pack according to (7), The end plate has a flange portion (flange portion 31f) on the surface facing the battery cell, The opening of the case is smaller than the flange portion of the end plate. Battery pack.

[0078] According to (8), the flanges of the end plates can prevent localized stress from acting on the battery cells when they are pressed. Furthermore, by making the opening of the case smaller than the flanges of the end plates, it is possible to prevent the opening from becoming larger and reducing the rigidity of the case.

[0079] (9) The battery pack according to (8), the space is provided around the flange portion of the end plate and the protrusion of the pressure plate; Battery pack.

[0080] According to (9), the flange portion of the end plate and the protrusion portion of the pressure plate can appropriately define and form a space for releasing pressure.

[0081] (10) A battery pack according to any one of (1) to (9), the pressure release valve is provided on the case so as to face a center portion of the battery cell when viewed from the stacking direction. Battery pack.

[0082] According to (10), the decrease in rigidity of the case can be suppressed. [Explanation of symbols]

[0083] 10 Battery pack 13 Pressure relief valve 16 spacer 16f flange 20 cases 28 Pressure Plate 281 Flange 282 Convex 31 End plate 31f flange 40 battery cells 44 Safety valve 46 Exhaust duct 47 Buffer Space (Space) 48 Exhaust flow path (flow path) 86b opening

Claims

1. a plurality of stacked battery cells each having a safety valve; end plates provided at the ends of the battery cells in the stacking direction; an exhaust duct that connects the safety valves of each battery cell and extends in the stacking direction; a case that houses the battery cells, the end plates, and the exhaust duct; a pressure release valve attached to a surface of the case facing the end plate, the pressure release valve being capable of venting gas released from the safety valve to the outside of the case, Between the exhaust duct and the pressure relief valve, a space formed around the end plate and communicating with the exhaust duct; a plurality of flow paths communicating the space with the pressure release valve; the end plate is provided on one end side of the battery cell in the stacking direction, the other end of the battery cell in the stacking direction abuts against the case, The battery cell is housed in the case while being pressed from the one end side toward the other end side. Battery pack.

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

3. 2. The battery pack according to claim 1, a spacer provided between the end plate and the case in the stacking direction and pressing the battery cell via the end plate; The plurality of flow paths are provided in the spacer. Battery pack.

4. 4. The battery pack according to claim 3, the end plate has a flange portion on a surface facing the battery cell, the spacer has a flange portion on a surface facing the case, At least a portion of the space is provided between the flange portion of the end plate and the flange portion of the spacer. Battery pack.

5. 2. The battery pack according to claim 1, The case is an opening provided on a surface facing the end plate; a pressure plate that is inserted into the opening and presses the battery cell via the end plate; the pressure release valve and the plurality of flow paths are provided in the pressure plate. Battery pack.

6. 6. The battery pack according to claim 5, The pressure plate is a flange portion facing an edge portion of the opening; a protrusion that protrudes from the opening toward the inside of the case and presses the battery cell via the end plate, The plurality of flow paths are provided in the convex portion. Battery pack.

7. 7. The battery pack according to claim 6, the end plate has a flange portion on a surface facing the battery cell, The opening of the case is smaller than the flange portion of the end plate. Battery pack.

8. 8. The battery pack according to claim 7, the space is provided around the flange portion of the end plate and the protrusion of the pressure plate; Battery pack.

9. 9. The battery pack according to claim 1, the pressure release valve is provided on the case so as to face a center portion of the battery cell when viewed from the stacking direction. Battery pack.

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