Battery pack

Abstract

To provide a battery pack which improves space efficiency and improves impact resistance against external impacts.SOLUTION: A battery pack 10 includes a plurality of stacked battery cells 40 and a case 20 that houses the plurality of battery cells 40. A closed opening 86a is provided in a left wall portion 86 of the case 20 in the stacking direction of the battery cells 40, and a pressure plate 28 is attached to the opening 86a to press the battery cells 40 against the case 20 in the stacking direction.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a battery pack. [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] For example, Patent Document 1 describes an energy storage device including an energy storage unit having a plurality of flat-shaped energy storage elements, and an exterior body that houses the energy storage unit. In the energy storage device of Patent Document 1, the energy storage unit is inserted through a second opening formed in a position facing a side wall of the exterior body and housed inside the exterior body, and then a second lid is joined to the exterior body so as to close the second opening. At this time, the second lid presses the plurality of energy storage elements in the arrangement direction via a spacer, thereby compressing the energy storage unit. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2023 / 068029 Summary of the Invention [Problem to be solved by the invention]

[0005] The energy storage device of Patent Document 1 is a cell-to-pack type in which multiple energy storage elements are housed in an exterior body without being unitized or modularized, which is advantageous in terms of space efficiency. However, since the second opening is formed by not providing a side wall on the side of the insertion opening for the energy storage unit in the exterior body, there is room for improvement in terms of impact resistance against external impacts.

[0006] The present invention provides a battery pack that improves space efficiency and shock resistance against external shocks, thereby contributing to energy efficiency. [Means for solving the problem]

[0007] The present invention provides A plurality of stacked battery cells; a case that houses the plurality of battery cells, a side wall portion of the case is provided with an opening that is closed around the periphery in the stacking direction of the battery cells, A pressure plate is attached to the opening to press the battery cells against the case in the stacking direction. 、 The pressure plate is a flange portion facing a peripheral edge portion of the opening; a protrusion that protrudes from the opening toward the inside of the case and presses the battery cell against the case, the flange portion of the pressure plate is fitted into the peripheral edge portion of the opening, and a step portion facing the flange portion of the pressure plate is provided, The flange portion of the pressure plate is provided inside the outer surface of the side wall portion of the case. . [Effects of the Invention]

[0008] According to the present invention, it is possible to improve space efficiency and also improve impact resistance against external impacts. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is an external perspective view of the battery pack 10. [Figure 2] FIG. 2 is an exploded perspective view of the battery pack 10. [Figure 3] FIG. 2 is an exploded perspective view of the cell stack 30. [Figure 4] 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 5] FIG. 10 is an exploded perspective view of a battery pack 10 according to a modified example. [Figure 6] FIG. 10 is a partial perspective view of a pressure plate 28 of a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0010] An embodiment of a battery pack of the present invention will be described below 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 in a device. For example, when the battery pack is mounted in a vehicle, the top and bottom of the battery pack may face the direction of travel of the vehicle or the width of the vehicle.

[0011] [Battery pack] 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. Note that a separator (not shown) may be arranged between adjacent battery cells 40. The binder 50 includes a rectangular lower restraint portion 51 that surrounds the bottom surface of the cell stack 30, a rectangular upper restraint portion 52 that surrounds 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, and 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.

[0012] The end plate 31 has flange portions 31f at the lower and upper ends, and the flange portions 31f are restrained by the lower restraining portion 51 and the upper restraining portion 52, thereby fixing the end plate 31 to the multiple battery cells 40.

[0013] 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.

[0014] 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.

[0015] Returning to Figure 2, the battery cell 40 is 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 configured as 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.

[0016] 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.

[0017] In addition, the upper ends of the front wall portion 82, rear wall portion 84, left wall portion 86, and right wall portion 87 of the case body 21 are continuously connected along the entire periphery.

[0018] An opening 86a that connects the cell accommodating space 25 to the outside is provided in the left wall portion 86. The opening 86a is provided in approximately the center of the left wall portion 86 in the up-down and front-rear directions, and is closed on all sides.

[0019] As shown in FIGS. 2 and 4 , a pressure plate 28 is attached to the opening 86a via a sealant 16 (e.g., a rubber seal). By fixing the pressure plate 28 to the left wall portion 86, the pressure plate 28 presses the battery cells 40 against the case 20 in the stacking direction. More specifically, by fixing the pressure plate 28 to the left wall portion 86, the pressure plate 28 comes into contact with the end plates 31 of the two cell stacks 30 through the opening 86a. By pressing the end plates 31 in the stacking direction, the multiple battery cells 40, which are temporarily fixed in place by the binder 50 at a predetermined pressure, are further compressed in the stacking direction and held within the case 20. The pressure plate 28 is fixed to the left wall portion 86 by welding, for example, friction stir welding.

[0020] In this way, in battery pack 10, multiple battery cells 40 can be held within case 20 by being pressed by pressure plate 28 without being modularized, thereby improving space efficiency and energy density. Also, because opening 86a is closed all around, a decrease in the rigidity of case 20 due to the provision of opening 86a can be suppressed compared to, for example, an opening whose all around is not closed (for example, an opening with an open upper end of the left wall), and impact resistance against external impacts can be improved.

[0021] Furthermore, since the pressure plate 28 faces the end plate 31 and presses the battery cells 40 against the case 20 via the end plate 31, the impact on the battery cells 40 can be mitigated when an external impact occurs, compared to when the pressure plate 28 presses the battery cells 40 directly without using the end plate 31.

[0022] The end plate 31 has a flange portion 31f provided on the surface that contacts the battery cell 40, and a protrusion 31p that contacts the pressure plate 28 and protrudes toward the left wall portion 86. The end plate 31 is configured so that the area of ​​the contact surface 311 that contacts the battery cell 40 (the surface on the flange portion 31f side) is larger than the area of ​​the contact surface 312 that contacts the pressure plate 28 (the surface on the protrusion 31p side). This makes it possible to prevent the battery cell 40 from being locally pressed.

[0023] Furthermore, the openings 86a are smaller than the abutment surfaces 311 of the end plates 31 that come into contact with the battery cells 40. Specifically, the lengths of the openings 86a in the up-down and front-rear directions are smaller than the lengths of the abutment surfaces 311 of the end plates 31 that come into contact with the battery cells 40. Because the openings 86a are small in this way, it is possible to further prevent a decrease in the rigidity of the case 20 due to the provision of the openings 86a.

[0024] Furthermore, because the end plates 31 are attached integrally to the battery cells 40 by the binders 50, even when pressed by the pressure plates 28, they can be prevented from shifting position relative to the battery cells 40.

[0025] 1 and 4, the pressure plate 28 is provided with two pressure release valves 13, each of which communicates with the cell accommodating space 25. A flow path (not shown) is formed in the pressure plate 28 that connects the exhaust duct 46 with the pressure release valve 13, and the pressure release valve 13 opens when gas generated from the safety valve 44 of the battery cell 40 causes an abnormal increase in the internal pressure of the cell accommodating space 25, thereby releasing the gas inside the case 20 to the outside.

[0026] The pressure plate 28 and the opening 86a will now be described in more detail.

[0027] 4, the pressure plate 28 has a flange 281 that faces the periphery of the opening 86a of the left wall 86, a protrusion 282 that protrudes from the opening 86a into the inside of the case 20 and presses against the battery cells 40 via the end plate 31, and two openings 283 to which the pressure release valves 13 are attached. The pressure plate 28 is fixed to the left wall 86 of the case body 21 at the flange 281, and the protrusion 282 protrudes from the opening 86a into the inside of the case 20 and presses against the multiple battery cells 40 via the end plate 31.

[0028] A step 86s is formed in the opening 86a at a position outside the case 20, and the pressure plate 28 is fixed to the left wall 86 so that the flange 281 fits into the step 86s via the sealant 16. In this case, the flange 281 of the pressure plate 28 is located inside the outer surface of the left wall 86, and the pressure plate 28 does not protrude from the outside of the left wall 86. With this configuration, when an impact is applied from the left of the case 20, a large portion of the left wall 86 absorbs the impact before it is applied to the pressure plate 28, thereby mitigating the impact applied to the battery cells 40 via the pressure plate 28 and end plate 31.

[0029] Furthermore, the sealant 16 is provided between the step 86s and the flange 281 of the pressure plate 28, thereby ensuring waterproofing of the case 20. In particular, in this embodiment, the step 86s is provided on the periphery of the opening 86a, which makes it easy to arrange the sealant 16.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] As shown in FIG. 2 , a case cover 23 is attached to the upper ends of the front wall 82, left wall 86, right wall 87, and rear wall 84 of the case body 21 via a first sealant 11 (e.g., a rubber seal). The case cover 23 is fixed to the upper surface of the case body 21 by welding, for example, by friction stir welding. A second sealant 12 (e.g., a foam sealant) is provided in the gap between the partition wall 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 85.

[0035] 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.

[0036] (Modified battery pack) 5, the case body 21 may further include a central wall portion 83 extending in the left-right direction between the front wall portion 82 and the rear wall portion 84. In this case, the cell stack 30 is housed between the front wall portion 82 and the central wall portion 83, and between the central wall portion 83 and the front wall portion 82, respectively.

[0037] In the above-described embodiment, the pressure plate 28 is attached to the opening 86a of the left wall portion 86 by welding such as friction stir welding, but this is not limited to this. For example, as shown in Fig. 6, a configuration may be adopted in which bolt insertion holes 285 are formed in the pressure plate 28 and the left wall portion 86, and bolts (not shown) passing through the bolt insertion holes 285 are fastened to bolt holes formed in the central wall portion 83 or the like, thereby attaching the pressure plate 28 to the left wall portion 86.

[0038] 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 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 embodiment may be combined in any manner without departing from the spirit of the invention.

[0039] 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.

[0040] 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.

[0041] (1) A plurality of stacked battery cells (battery cells 40); A battery pack (battery pack 10) including a case (case 20) that houses the plurality of battery cells, A side wall portion (left wall portion 86) of the case is provided with an opening (opening 86a) that is closed around the periphery in the stacking direction of the battery cells, A pressure plate (pressure plate 28) is attached to the opening to press the battery cells against the case in the stacking direction. Battery pack.

[0042] According to (1), multiple battery cells can be held in the case by being pressed by the pressure plate without modularizing them, thereby improving the space efficiency of the battery pack. Also, because the opening of the case where the pressure plate is installed is closed all around, a decrease in the rigidity of the case due to the opening can be suppressed, and impact resistance against external impacts can be improved.

[0043] (2) The battery pack according to (1), an end plate (end plate 31) provided at an end of the battery cell in the stacking direction and facing the pressure plate; the pressure plate presses the battery cell against the case via the end plate; Battery pack.

[0044] According to (2), by providing an end plate between the battery cell and the pressure plate, the impact on the battery cell can be reduced compared to when the pressure plate directly presses the battery cell.

[0045] (3) The battery pack according to (2), The area of ​​the contact surface (contact surface 311) of the end plate with the battery cell is larger than the area of ​​the contact surface (contact surface 312) with the pressure plate. Battery pack.

[0046] According to (3), by increasing the contact area between the end plate and the battery cell, it is possible to prevent the battery cell from being locally pressed by the pressure plate.

[0047] (4) The battery pack according to (2) or (3), The opening is smaller than the contact surface (contact surface 311) of the end plate that contacts the battery cell. Battery pack.

[0048] According to (4), by making the opening small, it is possible to suppress a decrease in the rigidity of the case due to the opening.

[0049] (5) A battery pack according to any one of (2) to (4), The end plate is integrally attached to the plurality of battery cells by a restraining member (binder 50). Battery pack.

[0050] According to (5), it is possible to prevent the end plates from shifting in position relative to the battery cells.

[0051] (6) A battery pack according to any one of (1) to (5), The pressure plate is a flange portion (flange portion 281) facing the peripheral 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 against the case; Battery pack.

[0052] According to (6), the battery cells can be pressed by the protrusions of the pressure plate that protrude from the opening to the inside of the case.

[0053] (7) The battery pack according to (6), the flange portion of the pressure plate is fitted into the peripheral edge portion of the opening, and a step portion (step portion 86s) facing the flange portion of the pressure plate is provided, the flange portion of the pressure plate is provided inside the outer surface of the side wall portion of the case; Battery pack.

[0054] According to (7), since the side walls of the case absorb a large portion of the shock from outside the case, the input to the battery cells can be reduced.

[0055] (8) The battery pack according to (7), A sealant (sealant 16) is provided between the step portion of the case and the flange portion of the pressure plate. Battery pack.

[0056] According to (8), even if the pressure plate is provided at the opening in the side wall of the case, the waterproofness of the case can be ensured.

[0057] (9) A battery pack according to any one of (1) to (8), The case has the side wall portion and includes a case main body (case main body 21) in which the battery cell is housed, and a case cover (case cover 23) that covers the case main body from above, The upper end of the side wall portion of the case body is continuously connected along the entire periphery, The case cover is connected to the upper end of the case body via a sealant (first sealant 11). Battery pack.

[0058] According to (9), the upper end of the side wall of the case body is continuous along the entire periphery, which increases the rigidity of the case body. Also, the case cover is connected to the upper end of the case body via a sealant, which ensures the waterproofness of the case.

[0059] (10) A battery pack according to any one of (1) to (9), The pressure plate is provided with a pressure release valve (pressure release valve 13) that can exhaust gas released from a safety valve (safety valve 44) provided in the battery cell to the outside of the case. Battery pack.

[0060] According to (10), the gas released inside the case due to thermal runaway can be discharged to the outside of the case, and the pressure inside the case can be released, thereby preventing damage to the case. [Explanation of symbols]

[0061] 10 Battery pack 11 First sealing material (sealing material) 13 Pressure relief valve 16 Sealing material 20 cases 21 Case body 23 Case Cover 28 Pressure Plate 281 Flange 282 Convex 31 End plate 311 Contact surface 312 Contact surface 40 battery cells 44 Safety valve 50 Binder (restraining material) 86 Left wall (side wall) 86a opening 86s step section

Claims

1. A plurality of stacked battery cells; a case that houses the plurality of battery cells, a side wall portion of the case is provided with an opening that is closed around the periphery in the stacking direction of the battery cells, a pressure plate is attached to the opening to press the battery cells against the case in the stacking direction; The pressure plate is a flange portion facing a peripheral edge portion of the opening; a protrusion that protrudes from the opening toward the inside of the case and presses the battery cell against the case, the flange portion of the pressure plate is fitted into the peripheral edge portion of the opening, and a step portion facing the flange portion of the pressure plate is provided, the flange portion of the pressure plate is provided inside the outer surface of the side wall portion of the case; Battery pack.

2. 2. The battery pack according to claim 1, an end plate provided at an end of the battery cell in the stacking direction and facing the pressure plate; the pressure plate presses the battery cell against the case via the end plate; Battery pack.

3. 3. The battery pack according to claim 2, the area of ​​the end plate's contact surface with the battery cell is larger than the area of ​​the contact surface with the pressure plate; Battery pack.

4. 3. The battery pack according to claim 2, the opening is smaller than the surface of the end plate that abuts against the battery cell; Battery pack.

5. 3. The battery pack according to claim 2, the end plate is integrally attached to the plurality of battery cells by a restraining member; Battery pack.

6. 6. The battery pack according to claim 1, a sealant is provided between the step portion of the case and the flange portion of the pressure plate; Battery pack.

7. 6. The battery pack according to claim 1, the case has the side wall portion, a case main body in which the battery cell is housed, and a case cover that covers the case main body from above, The upper end of the side wall portion of the case body is continuously connected along the entire periphery, The case cover is connected to the upper end of the case body via a sealing material. Battery pack.

8. 6. The battery pack according to claim 1, The pressure plate is provided with a pressure release valve that can exhaust gas released from a safety valve provided in the battery cell to the outside of the case. Battery pack.

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