Battery module

Abstract

A battery module 1 includes: a battery laminate 10 including a plurality of battery cells 11 electrically connected in series and laminated on each other; and a holding member holding the plurality of battery cells 11 from a side surface of the battery laminate 10 and formed of an electroconductive material. The holding member is an electroconductive member extending along the direction in which the plurality of battery cells 11 are laminated, and has a side wall part 430 covering at least a part of a side surface of the battery laminate 10 close to the bottom surface of the battery laminate. The side wall part 430 includes a first side wall portion in which the distance between the side wall part 430 and the battery laminate 10 is a first distance, and a second side wall portion in which the distance between the side wall part 430 and the battery laminate is a second distance which is longer than the first distance.

Description

Battery module

[0001] The present invention relates to a battery module.

[0002] A battery module is known in which a drain structure is provided on the outer wall of a cover plate, allowing some of the water droplets on the connecting parts and bus bars to flow into a water storage groove in the drain structure, and the water in the water storage groove to be discharged through a first discharge hole and a second discharge hole (for example, Patent Document 1).

[0003] International Publication No. 2020 / 196210

[0004] However, the battery module described in Patent Document 1 has a fixed clearance between each cell and the side plate that covers the multiple cells. For example, if the battery module is submerged in water, electrical conduction occurs between the side plate and the cell, causing a spark. This causes a problem in that the battery module described in Patent Document 1 cannot guide the spark. This results in low protection performance of the battery module.

[0005] The problem to be solved by the present invention is to provide a battery module with improved protection performance.

[0006] The present invention solves the above problem by providing a side plate made of a conductive material having a side wall portion that covers at least the portion of the side surface of the battery stack that is closest to the bottom surface of the battery stack, and by providing a first side wall portion that sets the distance between the side wall portion and the battery stack to a first distance, and a second side wall portion that sets the distance between the side wall portion and the battery stack to a second distance.

[0007] According to the present invention, the protection performance of the battery module can be improved.

[0008] FIG. 1 is a perspective view of a battery pack. FIG. 2 is an exploded perspective view showing a battery module according to an embodiment of the present invention. FIG. 3 is a perspective view of the battery module shown in FIG. 1. FIG. 4 is an enlarged perspective view of a portion of the battery module shown in FIG. 1. FIG. 5 is a perspective view of a side plate shown in FIG. 1. FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 3. FIG. 7 is a side view of a portion of a battery module according to a modified embodiment of the present invention.

[0009] A battery module 1 according to this embodiment will be described with reference to the drawings. Fig. 1 is a perspective view of a battery pack 100. Fig. 2 is an exploded perspective view of the battery module 1. Fig. 3 is a perspective view of the battery module 1. Fig. 4 is an enlarged perspective view of a portion of the battery module 1. Fig. 5 is a perspective view of a side plate. Fig. 6 is a cross-sectional view taken along line VI-VI in Fig. 3.

[0010] As shown in FIG. 1 , the battery pack 100 includes a battery module 1 according to this embodiment and a battery case 2 that houses four battery modules 1. The battery pack 100 is installed below a vehicle seat (e.g., under the cabin floor) so that the bottom of the battery pack 100 is aligned with the bottom of the vehicle. The x-y plane in FIG. 1 corresponds to the bottom of the battery module 1 and the surface that lies along the bottom of the vehicle. The battery case 2 is a box-shaped case that houses multiple battery modules 1. Note that FIG. 1 illustrates only the battery modules 1 as components housed in the battery case 2, but the battery pack 100 also includes a junction box and other components in addition to the multiple battery modules 1. The number of battery modules 1 housed in the case 2 is not limited to four, and may be one to three, or five or more. The battery case 2 may have projections and recesses depending on the installation location under the vehicle.

[0011] The battery module 1 in this embodiment includes a battery stack 10, a cell holder 21, an end cell holder 22, an end plate 30, and a side plate 40. The battery stack 10 includes multiple battery cells 11. Note that in this embodiment, the number of battery cells 11 included in the battery stack 10 is not limited to the number shown in FIG. 1 and may be any number equal to or greater than two. Furthermore, the battery module 1 is not limited to the battery stack 10 and end plate 30 shown in FIG. 1 , and may include other components such as a cover that serves as a lid for the battery module 1, a bus bar holder, etc.

[0012] The battery cell 11 is a flat secondary battery. The battery cell 11 may be, but is not limited to, a lithium-ion secondary battery or other secondary battery. Multiple battery cells 11 are stacked on top of each other along the Y direction in the figure. The interior of the battery cell 11 is made up of, for example, multiple laminated secondary batteries stacked together and covered with an exterior material. The stacking direction (Y direction) of the battery cells 11 is parallel to the thickness direction of the battery cell 11. The battery cell 11 is formed in a rectangular parallelepiped shape surrounded by six sides. A positive terminal 12 and a negative terminal 13 are provided on the top surface, which is one of the six sides (see FIG. 4 ). The positive terminal 12 and the negative terminal 13 are electrically connected to the tabs of the secondary battery included in the battery cell 11. That is, the positive terminal 12 and the negative terminal 13 are provided above the battery cell 11 and extend from one surface (the surface along the YZ plane) of the rectangular parallelepiped battery cell 11.

[0013] Of the six surfaces of the battery cell 11, a pair of side surfaces (surfaces along the XZ plane) with the largest area are stacking surfaces of the battery cell 11. The pair of side surfaces (stacking surfaces) face each other.

[0014] A plurality of battery cells 11 are connected in series and stacked on top of each other to form a battery stack 10. Adjacent positive electrode terminals 12 and negative electrode terminals 13 are connected by bus bars 14. The bus bars 14 are made of metal and are plate-shaped conductive members.

[0015] The cell holder 21 is a component that fixes the position of a single battery cell 11. The multiple cell holders 21 are provided to correspond to the multiple battery cells 11 included in the battery stack 10, respectively. The end cell holder 22 fixes the battery cell 11a from the side of the outermost battery cell 11a among the multiple battery cells 11 included in the battery stack 10. The cell holder 21 and end cell holder 22 are formed from, for example, resin.

[0016] The outermost battery cell 11a has a total negative terminal 13a. The total negative terminal 13a is not connected to the terminals of adjacent battery cells 11 by bus bars 14. The voltage (negative potential) of the total negative terminal 13a is the highest among the terminals of the multiple battery cells 11. In other words, the outermost battery cell 11a is the cell with the highest negative voltage.

[0017] The end plate 30 is a unit that holds the battery stack 10 from the side, and includes screw holes for passing screws and a connector that electrically connects the general negative terminal 13a to the harness. The connector installed on the end plate 30 is housed in a terminal holder and is connected to the general negative terminal 13a via a bus bar or the like.

[0018] The side plates 40 hold the multiple battery cells 11 from the side surfaces of the battery stack 10. The side plates 40 are made of a conductive material. When stress is applied from outside the battery pack 100, the side plates 40 are components that capture and hold the multiple battery cells 11.

[0019] The detailed shape of the side plate 40 will be described with reference to FIGS. 4 to 6 . The side plate 40 is formed to extend along the stacking direction (Y direction) of the multiple battery cells 11. In other words, the side plate 40 is formed to extend along the longitudinal direction of the side surface of the battery stack 10. The side plate 40 has an outer frame 41 that surrounds the outer periphery of the side surface of the battery stack 10. The interior of the outer frame 41 has a window-like opening. The upper and lower parts of the outer frame 41 are bent to increase the strength of the side plate 40. A bent curved portion 41a is provided on the upper part of the outer frame 41, which corresponds to the main surface of the side plate 40. A curved portion 41b is formed on the lower part of the outer frame 41, similar to the upper part. In addition, curved portions 41c and d are formed on the front and rear ends of the outer frame 41 (ends located in the positive and negative directions of the Y axis). Screw holes for passing screws are also formed in the curved portions 41c and d.

[0020] The side plates 40 include an upper side plate 42 and a lower side plate 43 that include the upper frame of the outer frame 41. The side plates 40 are an integrated component that includes the upper side plate 42 and the lower side plate 43. The upper side plate 42 covers at least the portion of the side surface of the battery stack 10 that is closest to the top surface of the battery stack 10. The lower side plate 43 covers at least the portion of the side surface of the battery stack 10 that is closest to the bottom surface (lower surface) of the battery stack 10. In other words, the upper side plate 42 and the lower side plate 43 form side walls that cover the outer periphery of the side surface of the battery stack 10. Note that the side plates 40 do not necessarily have to be an integrated component; for example, the upper side plate 42 and the lower side plate 43 may be separate components.

[0021] The lower side plate 43 of the side plate 40 has a bulging portion on the outside of the side plate 40. The side wall portion 430, which corresponds to the inner wall of the lower side plate 43, has a distance d between the side wall portion 430 and the battery stack 10. １ The distance between the first side wall 431 and the side wall 430 and the battery stack 10 is d ２ The second side wall portion 432 has a distance (d ２ ) is the distance (d １ ) is longer than the distance (d １ , d ２ ) is the distance from the side surface of the battery stack 10 to the inner wall surface of the side plate 40.

[0022] The outwardly bulging portion of the side plate 40 corresponds to the second side wall portion 432. The second side wall portion 432 is spaced from the battery cell 11a by a distance (d ２ 6, the battery cell 11 located at the outermost position among the plurality of battery cells 11 corresponds to the battery cell 11a having the highest voltage, and the battery cells 11b to 11g arranged second to seventh from the outside are arranged in descending order of voltage. The second side wall portion 432 is spaced a distance (d ２ The first side wall portion 431 is disposed to face the battery cells 11a to 11d with a distance (d １) and is disposed so as to face the battery cells 11f and 11g. That is, the first side wall portion 431 is disposed so as to face the battery cells 11f and 11g with a distance d １ The second side wall portion 432 is disposed at a position where the distance between the second side wall portion 432 and the battery cell 11a having the total negative terminal 13a is d ２ It is placed at a position where

[0023] The second side wall portion 432 is spaced from the battery cell having the positive terminal by a distance of d ２ That is, the second side wall portion 432 may be disposed at a position where the distance (d ２ ) and a distance (d ２ ), the first side wall portion 431 may be disposed so as to face the battery cells 11 located at one end and the other end. The first side wall portion 431 may be disposed between the pair of second side wall portions 432 along the stacking direction (Y direction) of the plurality of battery cells 11. In this embodiment, the second side wall portion 432 is disposed so as to be spaced apart from the battery cell 11a by a distance (d ２ ) are arranged at least at positions where

[0024] Incidentally, if water enters a vehicle equipped with a battery pack 100 and the battery pack 100 becomes submerged, the bottom of the battery stack 10 will be submerged in water. If the water causes electrical conduction between the battery cells 11 and the side plates 40, sparks may occur. Sparks are likely to occur in areas with low resistance. In the battery module 1 according to this embodiment, the distance (d ２ >d １ ) between the battery cells 11f and 11g, which have a lower voltage than the battery cell 11a, and the side plate 40, １) is spaced apart. This allows the spark generation location to be guided to the area where the distance between the battery cell 11 and the side plate 40 is short. The battery cell 11a has a total negative terminal 13a and has a high negative voltage. If a spark occurs in the high-voltage battery cell 11, the spark will cause significant damage to the battery module 1. The battery module 1 guides the spark generation location to the low-voltage battery cells 11f and 11g, making it difficult for sparks to occur in the high-voltage battery cells 11a to 11d.

[0025] Furthermore, the battery module 1 guides the spark generation site to the lower side plate 43. When the battery module 1 is submerged in water, the lower side plate 43 is immersed in water, and the spark generation site is submerged in water, so damage to the battery module 1 caused by sparks can be suppressed.

[0026] As described above, the battery module 1 according to this embodiment includes a battery stack 10 and a side plate 40. The side plate 40 is a conductive member that extends in the stacking direction of the multiple battery cells 11, and has a side wall 430 that covers at least the portion of the side surface of the battery stack 10 that is close to the bottom surface of the battery stack 10. The side wall 430 defines a distance d between the side wall 430 and the battery stack 10. １ The distance between the first side wall 431 and the side wall 430 and the battery stack 10 is defined as d １ Longer d ２ (corresponding to the "second distance" of the present invention) and a second side wall portion 432. This allows the spark generation site to be guided to a portion close to the bottom surface of the battery stack 10, thereby improving the protection performance of the battery module 1.

[0027] In this embodiment, the side wall portion 432 is spaced from the battery cell 11 with the highest voltage among the plurality of battery cells 11 by a distance d ２ This allows the spark generation location to be guided to the part of the battery cell 11 with a low voltage, thereby suppressing the discharge energy in the event of a short circuit.

[0028] In this embodiment, the battery cells 11 are flat cells, and the stacking direction of the battery cells 11 is parallel to the thickness direction of the battery cells 11. This allows a large number of cells to be provided when the battery module 1 is mounted in a limited space such as under a seat.

[0029] The battery module 1 according to this embodiment also includes bus bars 14 that connect the output terminals (positive terminal 12 and negative terminal 13) of the battery cells 11 together, and the output terminals are provided above the battery cells 11. This makes it difficult for the output terminals to become immersed in water when the battery module 1 is submerged, thereby suppressing discharge energy in the event of a short circuit.

[0030] In this embodiment, the side wall portion 432 is spaced from the battery cell 11 having the total negative terminal 13 by a distance d ２ This allows the spark generation location to be guided to a location that avoids the high-voltage battery cell 11, thereby suppressing discharge energy in the event of a short circuit.

[0031] In the battery module 1 according to the modified example of this embodiment, when viewed from the side perpendicular to the stacking direction, the area of ​​the overlapping portion between the side wall portion 430 and the plurality of battery cells 11 may be such that the area of ​​the portion corresponding to the low-voltage battery cells 11 is larger than the area of ​​the portion corresponding to the high-voltage battery cells 11.

[0032] FIG. 7 is a side view of a battery module 1 according to a modified example. The side plate 40 has a notch 42 in a portion facing the battery cell 11a. The notch 411 is provided to reduce the area of ​​the overlap between the side wall portion 432 and the battery cell 11. On the other hand, the notch 411 is not provided in a portion facing the low-voltage battery cells 11c to 11g. The notch 411 is not provided at least in the side wall portion 431. The resistance between the side wall portion 430 and the multiple battery cells 11 is determined by the area of ​​the mutually opposing portions between the side wall portion 430 and the multiple battery cells 11. In the example of FIG. 7 , in a side view from the negative direction of the X axis, the area of ​​region 71 facing the battery cell 11a with the highest voltage is the smallest, the area of ​​region 72 facing the battery cell 11b with the second highest voltage is the second smallest, and the area of ​​region 73 facing the battery cells 11c to 11h is larger than the areas 71 and 72. The side plate 40 may be configured so that the areas of the regions 71 to 73 facing the battery cells 11 are smallest in the portion facing the battery cell 11 with the highest voltage, and the areas of the regions 71 to 73 increase as the voltage of the facing battery cell 11 decreases. In this embodiment, the resistance between the second side wall portion 432, which includes at least the regions 71 and 72, and the battery cells 11a and 11b increases, while the resistance between the first side wall portion 431, which does not include the regions 71 and 72 but includes the region 73, and the battery cell 11a decreases. This allows the spark generation site to be guided to the portion corresponding to the battery cell 11 with the lowest voltage, thereby improving the protection performance of the battery module 1.

[0033] The side plate 40 corresponds to the "holding member" of the present invention, the battery cells 11f, g, and h correspond to the "first battery cell" of the present invention, and the battery cell 11a and / or the battery cell 11b correspond to the "second battery cell" of the present invention.

[0034] DESCRIPTION OF SYMBOLS 1...Battery module 2...Battery case 2...Case 10...Battery stack 11, 11a to 11h...Battery cell 12...Positive terminal 13...Negative terminal 13a...Total negative terminal 14...Bus bar 21...Cell holder 22...End cell holder 30...End plate 40...Side plate 100...Battery pack 430...Side wall portion 431...First side wall portion 432...Second side wall portion

Claims

1. A battery module comprising: a battery stack including a plurality of battery cells electrically connected in series and stacked on top of each other; and a holding member made of a conductive material that holds the plurality of battery cells from a side surface of the battery stack, wherein the holding member is a conductive member that extends in the stacking direction of the plurality of battery cells and has a side wall portion that covers at least a portion of the side surface of the battery stack that is close to the bottom surface of the battery stack, and the side wall portion includes a first side wall portion that sets the distance between the side wall portion and the battery stack to a first distance, and a second side wall portion that sets the distance between the side wall portion and the battery stack to a second distance that is longer than the first distance.

2. A battery module according to claim 1, wherein the second side wall portion is positioned so that the distance from the battery cell with the highest voltage among the plurality of battery cells is the second distance.

3. A battery module according to claim 1 or 2, wherein the battery cells are flat cells, and the stacking direction is parallel to the thickness direction of the battery cells.

4. A battery module according to any one of claims 1 to 3, wherein the plurality of battery cells comprises a first battery cell and a second battery cell having a higher voltage than the first battery cell, and when viewed from the side perpendicular to the stacking direction, the area of ​​the overlapping portion between the side wall portion and the plurality of battery cells is such that the area of ​​the portion corresponding to the first battery cell is larger than the area of ​​the portion corresponding to the second battery cell.

5. A battery module according to any one of claims 1 to 4, comprising a bus bar connecting the output terminals of the battery cells, the output terminals being provided above the battery cells.

6. A battery module according to any one of claims 1 to 5, wherein the second side wall portion is positioned so that the distance from the battery cell having the total negative terminal among the plurality of battery cells is the second distance.

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