Battery module

Abstract

The gas generated from the battery cell is efficiently discharged from between the battery cell and the protector. [Solution] The battery module 1 comprises a plurality of battery cells 10 and a first protector 20 located on at least one side of the plurality of battery cells 10. The first protector 20 has a plurality of holes 22 for discharging gas generated from the battery cells 10 from between the battery cells 10 and the first protector 20.

Description

Technical Field

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

Background Art

[0002] In recent years, various battery modules have been developed. For example, as described in Patent Document 1, a battery module may include a plurality of battery modules and a protector located in front of the plurality of battery modules.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Gas may be generated from the battery cells due to factors such as abnormalities in the battery cells. When a protector is located on at least one side such as the front of the battery module, it may be necessary to efficiently discharge the gas generated from the battery cells between the battery cells and the protector.

[0005] An example of the object of the present invention is to efficiently discharge the gas generated from the battery cells between the battery cells and the protector. Other objects of the present invention will become apparent from the description herein.

Means for Solving the Problems

[0006] One aspect of the present invention is as follows. 1. A plurality of battery cells, a protector located on at least one side of the plurality of battery cells, and comprising The battery module is characterized in that the protector has a discharge structure for discharging gas generated from the battery cell from between the battery cell and the protector. 2. The battery cell has other discharge structures for discharging gas generated from inside the battery cell, The battery module according to 1, wherein the discharge structure of the protector and the other discharge structure of the battery cell overlap each other at least partially. 3. The battery module according to 1. or 2., wherein the discharge structure is defined by at least one of a hole provided in the protector and a thin-walled portion provided in the protector. [Effects of the Invention]

[0007] According to the above embodiment of the present invention, gas generated from the battery cell can be efficiently discharged from between the battery cell and the protector. [Brief explanation of the drawing]

[0008] [Figure 1] This is a perspective view of a battery module according to an embodiment. [Figure 2] This is a side view of a battery module according to an embodiment. [Figure 3] This is a top view of a battery module according to an embodiment. [Figure 4] This is a front view of the battery module according to the embodiment. [Figure 5] This is a cross-sectional view along line AA in Figure 4. [Figure 6] This diagram illustrates the gas flow discharged from the first protruding edge of each battery cell. [Figure 7] This is a front view of a modified battery cell. [Modes for carrying out the invention]

[0009] Embodiments and modified examples of the present invention will be described below with reference to the drawings. In all drawings, similar components are denoted by the same reference numerals, and their descriptions are omitted where appropriate.

[0010] Figure 1 is a perspective view of the battery module 1 according to the embodiment. Figure 2 is a side view of the battery module 1 according to the embodiment. Figure 3 is a top view of the battery module 1 according to the embodiment. Figure 4 is a front view of the battery module 1 according to the embodiment. Figure 5 is a cross-sectional view along line AA in Figure 4.

[0011] Figures 1 to 5 show the X-axis, Y-axis, and Z-axis, respectively, for illustrative purposes. In Figure 2, the white circle with a black dot indicating the Y-axis indicates that the Y-axis arrow is pointing towards the front of the page. In Figures 3 and 5, the white circle with a black dot indicating the Z-axis indicates that the Z-axis arrow is pointing towards the front of the page. In Figure 4, the white circle with a black dot indicating the X-axis indicates that the X-axis arrow is pointing towards the front of the page. The X-axis indicates the front-to-back direction of the battery module 1. The Y-axis is one of the directions perpendicular to the X-axis and indicates the left-to-right direction of the battery module 1. The Z-axis is a direction perpendicular to both the X-axis and Y-axis and indicates the up-to-down direction of the battery module 1. Hereafter, unless otherwise specified, the directions indicated by the X-axis arrow, the Y-axis arrow, and the Z-axis arrow will be described as the front, left, and up directions of the battery module 1, respectively. The front-to-back, left-to-right, and up-to-down directions of the battery module 1 are not limited to the examples given above.

[0012] Unless otherwise specified, the +X side refers to the side indicated by the X-axis arrow, and the -X side refers to the opposite side of the side indicated by the X-axis arrow. Unless otherwise specified, the +Y side refers to the side indicated by the Y-axis arrow, and the -Y side refers to the opposite side of the side indicated by the Y-axis arrow. Unless otherwise specified, the +Z side refers to the side indicated by the Z-axis arrow, and the -Z side refers to the opposite side of the side indicated by the Z-axis arrow.

[0013] As shown in FIG. 1, the battery module 1 according to the embodiment includes a plurality of battery cells 10, a first protector 20, a plurality of first long partition bodies 31, a plurality of first short partition bodies 32, a second protector 40, a plurality of second long partition bodies 51, a plurality of second short partition bodies 52, a first plate 61, and a second plate 62.

[0014] As shown in FIGS. 1, 3, and 5, the plurality of battery cells 10 are stacked in the Y direction. As can be seen from FIGS. 1, 2, 3, and 5, each battery cell 10 has a battery element 11, an exterior member 12, a positive electrode lead 13, and a negative electrode lead 14. In FIGS. 2 and 3, for the sake of explanation, the outer contour line of the battery element 11 is illustrated by a dashed line.

[0015] As can be seen from FIGS. 2, 3, and 5, the battery element 11 has a substantially rectangular parallelepiped shape having a pair of surfaces substantially perpendicular to the X direction, a pair of surfaces substantially parallel to the Y direction, and a pair of surfaces substantially parallel to the Z direction. As can be seen from FIGS. 2, 3, and 5, the dimensions of each side of the battery element 11 are in the order of the side substantially parallel to the Y direction, the side substantially parallel to the Z direction, and the side substantially parallel to the X direction, becoming longer. For example, the battery element 11 includes a plurality of positive electrodes and a plurality of negative electrodes alternately stacked in the Y direction, and a separator positioned between adjacent positive and negative electrodes. The positive and negative electrodes of the battery element 11 may be wound around the X direction. The shape of the battery element 11 is not limited to the example shown in FIGS. 2, 3, and 5.

[0016] The exterior member 12 wraps the battery element 11. In the embodiment, the battery element 11 seals the battery element 11 and the electrolytic solution. The battery cell 10 may be an all-solid-state battery that does not use an electrolytic solution.

[0017] As shown in FIGS. 1, 3, and 5, the exterior member 12 has a first film 12a covering the -Y side portion of the battery element 11 and a second film 12b covering the +Y side portion of the battery element 11. The first film 12a and the second film 12b are laminate films and include, for example, a metal foil such as an aluminum foil.

[0018] As shown in FIG. 2, the first film 12a and the second film 12b form the first sealing side 121, the second sealing side 122, the third sealing side 123, and the fourth sealing side 124 around the battery element 11 in the Y direction. At the first sealing side 121, the second sealing side 122, the third sealing side 123, and the fourth sealing side, the first film 12a and the second film 12b are joined to each other by sealing such as welding. The first sealing side 121 extends in the X direction along the +Z side surface of the battery element 11. In the embodiment, the first sealing side 121 is bent along a plane perpendicular to the Z direction, and the bent shape of the first sealing side 121 is fixed by a plurality of first fixing tapes 121a. The second sealing side 122 extends in the X direction along the -Z side surface of the battery element 11. In the embodiment, the second sealing side 122 is bent along a plane perpendicular to the Z direction, and the bent shape of the second sealing side 122 is fixed by a plurality of second fixing tapes 122a. The third sealing side 123 is located on the +X side with respect to the +X side surface of the battery element 11. The fourth sealing side 124 is located on the -X side with respect to the -X side surface of the battery element 11.

[0019] As can be seen from FIGS. 2 and 5, the +X side portions of the first film 12a and the second film 12b form a first taper 125 in which the Y-direction interval between the first film 12a and the second film 12b decreases as the +X side portions of the first film 12a and the second film 12b move away from the +X side surface of the battery element 11 in the +X direction. Similar to the +X side portions of the first film 12a and the second film 12b, the -X side portions of the first film 12a and the second film 12b form a second taper 126 in which the Y-direction interval between the first film 12a and the second film 12b decreases as the -X side portions of the first film 12a and the second film 12b move away from the -X side surface of the battery element 11 in the -X direction.

[0020] As shown in Figure 2, the third sealing edge 123 includes a first protruding edge 123a located on the +X side relative to the +X end of the first taper 125, a first concave edge 123b located on the +Z side relative to the first protruding edge 123a and the first taper 125, and a second concave edge 123c located on the -Z side relative to the first protruding edge 123a and the first taper 125. The first protruding edge 123a protrudes on the +X side from the first concave edge 123b and the first concave edge 123b. The center of the first protruding edge 123a in the Z direction is located on the -Z side relative to the center of the third sealing edge 123 in the Z direction. The Z-direction dimensions of the first protruding edge 123a and the first concave edge 123b are each greater than the Z-direction dimension of the second concave edge 123c.

[0021] As shown in Figure 2, the fourth sealing edge 124 includes a second protruding edge 124a located -X side with respect to the -X end of the second taper 126, a third concave edge 124b located +Z side with respect to the second protruding edge 124a and the second taper 126, and a fourth concave edge 124c located -Z side with respect to the second protruding edge 124a and the second taper 126. The second protruding edge 124a protrudes -X side more than the third concave edge 124b and the fourth concave edge 124c. The Z-direction center of the second protruding edge 124a is located -Z side with respect to the Z-direction center of the fourth sealing edge 124. The Z-direction dimensions of the second protruding edge 124a and the Z-direction dimensions of the third concave edge 124b are each greater than the Z-direction dimension of the fourth concave edge 124c.

[0022] The structure of the outer casing 12 is not limited to the example shown in Figure 2. For example, the outer casing 12 may consist of a single film folded over on the +Z side or the -Z side of the battery element 11. When the film is folded over on the -Z side of the battery element 11, the outer casing 12 forms a sealing edge around the Y direction of the battery element 11, except for the -Z side where the film is folded over. When the film is folded over on the +Z side of the battery element 11, the outer casing 12 forms a sealing edge around the Y direction of the battery element 11, except for the +Z side where the film is folded over.

[0023] The positive lead 13 is electrically connected to the positive electrode of the battery element 11, and the negative lead 14 is electrically connected to the negative electrode of the battery element 11. In some embodiments, the positive lead 13 is formed of at least one of aluminum and an aluminum alloy. In some embodiments, the negative lead 14 is formed of at least one of copper and a copper alloy. The materials forming the positive lead 13 and the negative lead 14 are not limited to the materials described above. As can be seen from Figures 1, 2, 3, and 5, the positive lead 13 is drawn out from one of the first protruding edge 123a and the second protruding edge 124a. As can be seen from Figures 1, 2, 3, and 5, the negative lead 14 is drawn out from the other of the first protruding edge 123a and the second protruding edge 124a.

[0024] As shown in Figure 2, when the negative electrode lead 14 is drawn out from the second protruding edge 124a, the -X end of the second protruding edge 124a from which the negative electrode lead 14 is drawn is covered with insulating tape 124d. Therefore, even if the first film 12a and the second film 12b contain aluminum foil and the negative electrode lead 14 is formed of copper and a copper alloy, contact between the aluminum contained in the first film 12a and the second film 12b and the copper forming the negative electrode lead 14 can be suppressed by the insulating tape 124d. Thus, corrosion of the exterior material 12 or the negative electrode lead 14 due to contact between the dissimilar materials of aluminum and copper can be suppressed. When the negative electrode lead 14 is drawn out from the first protruding edge 123a, similar to the example shown in Figure 2, the +X end of the first protruding edge 123a from which the negative electrode lead 14 is drawn is covered with insulating tape corresponding to insulating tape 124d.

[0025] Multiple battery cells 10 have multiple battery cells 10 connected in parallel. Hereafter, unless otherwise specified, a parallel cell 10a refers to a battery cell 10 connected in parallel. As can be seen from Figures 1, 3 and 5, in the embodiment, a parallel cell 10a includes two battery cells 10 adjacent to each other in the Y direction. The two battery cells 10 included in a parallel cell 10a are connected in parallel by the positive electrode leads 13 located on one of the +X and -X sides of the two battery cells 10 being electrically connected to each other, and the negative electrode leads 14 located on the other of the +X and -X sides of the two battery cells 10 being electrically connected to each other. Two parallel cells 10a adjacent to each other in the Y direction are connected in series by the positive electrode lead 13 located on one of the +X and -X sides of one of the parallel cells 10a and the negative electrode lead 14 located on one of the +X and -X sides of the other parallel cell 10a being electrically connected to each other. Unless otherwise specified, the lead group 15 refers to the positive electrode lead 13 located on one of the +X and -X sides of one of two parallel cells 10a adjacent in the Y direction, and the negative electrode lead 14 located on one of the other parallel cells 10a adjacent in the Y direction. The positive electrode lead 13 and negative electrode lead 14 included in the lead group 15 are electrically connected to each other. As can be seen from Figure 1, the multiple parallel cells 10a are connected in series via multiple lead groups 15 that are alternately located in the X direction, from the parallel cell 10a located at one end of the multiple battery cells 10 in the Y direction to the parallel cell 10a located at the other end of the multiple battery cells 10 in the Y direction.

[0026] The electrical connections of the multiple battery cells 10 are not limited to the examples in this embodiment. For example, a parallel cell 10a may include three or more battery cells 10 connected in parallel. Alternatively, there may be no parallel-connected battery cells 10, and multiple single battery cells 10 may be connected in series.

[0027] As shown in Figure 5, on the +X side of the parallel cell 10a, the two first tapers 125 of the two battery cells 10 included in the parallel cell 10a are bent so that they move closer to each other as they move toward the +X side. As shown in Figure 5, the positive electrode lead 13 included in the lead group 15 on the +X side is bent at approximately a right angle toward the +Y side, and the negative electrode lead 14 included in the lead group 15 on the +X side is bent at approximately a right angle toward the -Y side. As shown in Figure 5, in the lead group 15 on the +X side, the positive electrode lead 13 and the negative electrode lead 14 overlap at least partially in the X direction. In the lead group 15 on the +X side, the -X side surface of the positive electrode lead 13 and the +X side surface of the negative electrode lead 14 are joined to each other, for example by welding, so that the positive electrode lead 13 and the negative electrode lead 14 included in the lead group 15 are electrically connected to each other. On the -X side of the parallel cell 10a, the positive lead 13 and negative lead 14 included in the lead group 15 on the -X side are electrically connected to each other, similar to the positive lead 13 and negative lead 14 included in the lead group 15 on the +X side.

[0028] The first protector 20 is positioned on the +X side portion of the multiple battery cells 10. The first protector 20 has electrical insulating properties and is made of a resin such as PBT (polybutylene terephthalate). As shown in Figure 1, the first protector 20 defines multiple openings 21 that expose multiple +X side lead groups 15. The first protector 20 covers substantially the entire +X side portion of the multiple battery cells 10, except for the portion that overlaps with the multiple openings 21 of the multiple battery cells 10 in the X direction.

[0029] In one embodiment, the first protector 20 is provided to hold wiring (not shown), such as a voltage detection harness, which is electrically connected to a plurality of +X-side lead groups 15. This wiring can be routed through the first protector 20. In another embodiment, the first protector 20 is also provided to hold a busbar (not shown) which is electrically connected to a positive electrode lead 13 drawn out to the +X side from a parallel cell 10a located at the +Y-side end of a plurality of battery cells 10. This busbar can be attached to the +Y-side end of the first protector 20.

[0030] The second protector 40 is positioned on the -X side portion of the multiple battery cells 10. The second protector 40 has electrical insulating properties and is formed of a resin such as PBT (polybutylene terephthalate). Similar to the first protector 20, the second protector 40 defines multiple openings that expose the multiple -X side lead groups 15. From the viewpoint shown in Figure 1, the multiple openings of the second protector 40 are hidden by the multiple battery cells 10. Similar to the first protector 20, the second protector 40 covers substantially the entire -X side portion of the multiple battery cells 10, except for the portion that overlaps with the multiple openings of the second protector 40 in the X direction.

[0031] In one embodiment, the second protector 40 is provided to hold wiring (not shown), such as a voltage detection harness, which is electrically connected to a plurality of lead groups 15 on the -X side. This wiring can be routed through the second protector 40. In another embodiment, the second protector 40 is also provided to hold a busbar (not shown) which is electrically connected to a negative electrode lead 14 drawn out to the -X side from a parallel cell 10a located at the -Y side end of a plurality of battery cells 10. This busbar can be attached to the -Y side end of the second protector 40.

[0032] The first plate 61 and the second plate 62 constitute a part of a housing that accommodates a plurality of battery cells 10, a first protector 20, and a second protector 40. The first plate 61 covers the -Y side portion of the plurality of battery cells 10. The second plate 62 covers the -Z side portion of the plurality of battery cells 10. The housing further includes a plate (not shown) located on the +X side with respect to the first protector 20 and covering the +X side portion of the plurality of battery cells 10 and the first protector 20, a plate (not shown) located on the -X side with respect to the second protector 40 and covering the -X side portion of the plurality of battery cells 10 and the second protector 40, a plate (not shown) covering the +Y side portion of the plurality of battery cells 10, and a plate (not shown) covering the +Z side portion of the plurality of battery cells 10.

[0033] A relatively high-temperature gas may be generated from inside each battery cell 10 due to an abnormality in the battery elements 11 or other components of each battery cell 10. This gas may cause the first film 12a and the second film 12b to rupture at any of the first sealing edge 121, second sealing edge 122, third sealing edge 123, or fourth sealing edge 124. The portion of the first film 12a and the second film 12b that ruptures due to the gas functions as a discharge structure for releasing the gas generated from inside the battery cell 10. In this embodiment, the positions where the first film 12a and the second film 12b are most likely to rupture are as follows.

[0034] As shown in Figure 2, the dimensions of the first concave side 123b and the third concave side 124b in the Z direction are larger than the dimensions of the second concave side 123c and the fourth concave side 124c, respectively. The first concave side 123b and the third concave side 124b are not folded as much as the second protruding side 124a and the second protruding side 124a, respectively. Therefore, the internal pressure of the battery cell 10 is most likely to be applied to the first concave side 123b and the third concave side 124b. Consequently, the gas generated from the battery cell 10 makes the first film 12a and the second film 12b most likely to tear at the first concave side 123b and the third concave side 124b.

[0035] As shown in Figure 2, the dimensions of the first protruding edge 123a and the second protruding edge 124a in the Z direction are larger than the dimensions of the second concave edge 123c and the fourth concave edge 124c, respectively. On the other hand, the internal pressure of the battery cell 10 is less likely to be applied to the first protruding edge 123a and the second protruding edge 124a than to the first concave edge 123b and the third concave edge 124b due to the bending of the first taper 125 and the second taper 126. Therefore, the first film 12a and the second film 12b are most likely to rupture at the first protruding edge 123a and the second protruding edge 124a, after the first concave edge 123b and the third concave edge 124b, due to the gas generated from the battery cell 10. As shown in Figure 2, when the -X end of the second protruding edge 124a is covered with insulating tape 124d, the second protruding edge 124a is less likely to tear than the first protruding edge 123a due to the insulating tape 124d.

[0036] As shown in Figure 2, the Z-direction dimension of the second concave side 123c is less than the Z-direction dimension of the first protruding side 123a and the first concave side 123b. As shown in Figure 2, the Z-direction dimension of the fourth concave side 124c is less than the Z-direction dimension of the second protruding side 124a and the third concave side 124b. For reasons to be described later, the first film 12a and the second film 12b are more prone to tearing at the second concave side 123c and the fourth concave side 124c than at the first sealing side 121 and the second sealing side 122. However, the first film 12a and the second film 12b are less prone to tearing at the second concave side 123c and the fourth concave side 124c than at the first protruding side 123a, the first concave side 123b, the second protruding side 124a and the third concave side 124b.

[0037] The first sealing edge 121 and the second sealing edge 122 are bent along a plane perpendicular to the Z direction, and the bent shape of the first sealing edge 121 and the bent shape of the second sealing edge 122 are fixed by a plurality of first fixing tapes 121a and a plurality of second fixing tapes 122a, respectively. Therefore, among the first sealing edge 121, the second sealing edge 122, the third sealing edge 123, and the fourth sealing edge 124 of the first film 12a and the second film 12b, the first sealing edge 121 and the second sealing edge 122 are the least likely to tear.

[0038] As shown in Figures 1 to 5, a plurality of first elongated partitions 31 are provided on the -X side portion of the first protector 20. Each first elongated partition 31 has a substantially plate shape that is substantially perpendicular to the Y direction. In this embodiment, each first elongated partition 31 is a cation-coated iron plate. Since the first elongated partition 31 is made of iron, even if the thickness of the first elongated partition 31 in the Y direction is relatively thin, for example, about 0.1 mm to 1 mm, the first elongated partition 31 can maintain relatively high heat resistance. Since the material forming the first elongated partition 31 is cation-coated, the surface of the first elongated partition 31 is insulated, and a short circuit between the battery cell 10 and the first elongated partition 31 can be suppressed. The material forming each first elongated partition 31 is not limited to the above example, as long as it has relatively high heat resistance, it may be a metal other than iron, for example. If the first elongated partition 31 is made of metal, the metal forming the first elongated partition 31 does not need to be insulated by cationic coating or the like.

[0039] As can be seen from Figures 2 and 4, the dimensions of the first elongated partition 31 in the Z direction and the dimensions of the third sealing edge 123 in the Z direction are approximately equal. As can be seen from Figure 2, when viewed from the Y direction, the first elongated partition 31 overlaps at least partially with the first protruding edge 123a, the first concave edge 123b, and the second concave edge 123c in the Y direction. Therefore, each first elongated partition 31 at least partially partitions the first protruding edges 123a, the first concave edges 123b, and the second concave edges 123c of the parallel cells 10a connected in series via the lead group 15 on the -X side. Therefore, the gas discharged from the first protruding side 123a, first concave side 123b, or second concave side 123c of one of the parallel cells 10a connected in series via the lead group 15 on the -X side can be blocked by the first long partition 31 from the other parallel cell 10a connected in series via the lead group 15 on the -X side. Therefore, the heat chain between the parallel cells 10a connected in series via the lead group 15 on the -X side can be suppressed by the first long partition 31.

[0040] As shown in Figures 1, 2, and 4, the multiple first short partitions 32 are provided on the -X side portion of the first protector 20. Each first short partition 32 has a substantially plate shape that is substantially perpendicular to the Y direction. In the embodiment, each first short partition 32 is a cation-coated iron plate, similar to each first long partition 31. However, the material forming the first short partitions 32 may be a metal other than iron, similar to the material forming the first long partition 31.

[0041] As can be seen from Figure 4, each first short partition 32 is located on the +Z side relative to the lead group 15 on the +X side. Viewed from the Y direction, each first short partition 32 overlaps at least partially with the first concave edge 123b in the Y direction. Therefore, each first short partition 32 at least partially separates the first concave edges 123b of the parallel cells 10a connected in series via the lead group 15 on the +X side. Consequently, the gas discharged from the first concave edge 123b of one of the parallel cells 10a connected in series via the lead group 15 on the +X side can be blocked by the first short partition 32 from the other parallel cell 10a connected in series via the lead group 15 on the +X side. Therefore, the heat chain between the parallel cells 10a connected in series via the lead group 15 on the +X side can be suppressed by the first short partition 32.

[0042] The first short partition 32 does not separate the first protruding edges 123a and the second recessed edges 123c of the parallel cells 10a connected in series via the lead group 15 on the +X side. As described above, the first film 12a and the second film 12b are less prone to tearing at the first protruding edges 123a and the second recessed edges 123c compared to the first recessed edge 123b. Therefore, by separating the first recessed edges 123b of the parallel cells 10a connected in series via the lead group 15 on the +X side with the first short partition 32, the heat chain between the parallel cells 10a connected in series via the lead group 15 on the +X side can be sufficiently suppressed. Furthermore, it is not necessary to place the first short partition 32 near the lead group 15 on the +X side, and it is easier to suppress short circuits between the lead group 15 and the first short partition 32.

[0043] The first long partition 31 and the first short partition 32 are supported by the first protector 20. As can be seen from Figure 3, the first long partition 31 does not extend into the area between the battery elements 11 of the battery cells 10 located on both sides of the first long partition 31 in the Y direction, and the first short partition 32 does not extend into the area between the battery elements 11 of the battery cells 10 located on both sides of the first short partition 32 in the Y direction. Therefore, compared to the case where the first long partition 31 extends between the battery elements 11 of the battery cells 10 located on both sides of the first long partition 31 in the Y direction, the dimensions of the multiple battery cells 10 in the Y direction can be reduced, and the volumetric energy density of the battery module 1 can be increased. Similarly, compared to the case where the first short partition 32 is positioned between the battery elements 11 of the battery cells 10 located on both sides of the first short partition 32 in the Y direction, the dimensions of the multiple battery cells 10 in the Y direction can be reduced, and the volumetric energy density of the battery module 1 can be increased.

[0044] In this embodiment, the first long partition 31 and the first short partition 32 are molded separately from the first protector 20. In other examples, the first long partition 31 and the first short partition 32 may be made of resin molded integrally with the first protector 20. Even if the first long partition 31 and the first short partition 32 are made of resin, by making the thickness of the first long partition 31 and the first short partition 32 in the Y direction greater than the thickness of other parts of the first protector 20, the first long partition 31 and the first short partition 32 can be made to have the heat resistance necessary to function as partitions that block gas generated from the battery cell 10. By molding the first long partition 31 and the first short partition 32 integrally with the first protector 20, the first protector 20, the first long partition 31 and the first short partition 32 can be easily formed.

[0045] As shown in Figures 1 and 2, the multiple second elongated partitions 51 are provided on the +X side portion of the second protector 40. The second elongated partitions 51 can be similar to the first elongated partitions 31, except that the second elongated partitions 51 at least partially partition the second protruding sides 124a, the third recessed sides 124b, and the fourth recessed sides 124c of the parallel cells 10a connected in series via the lead group 15 on the +X side.

[0046] As shown in Figure 1, the multiple second short partitions 52 are provided on the +X side portion of the second protector 40. The second short partitions 52 can be made similar to the first short partitions 32, except that the second short partitions 52 separate the third concave edges 124b on the -X side of the parallel cells 10a that are connected in series via the lead group 15 on the -X side.

[0047] As shown in Figures 1 and 4, the first protector 20 defines a plurality of holes 22. In this embodiment, as can be seen in Figure 4, three holes 22 are provided for each battery cell 10, except for the battery cell 10 located furthest to the +Y side. In Figure 4, the dashed lines passing through the three holes 22 provided for each battery cell 10 indicate positions that overlap in the X direction with the first concave side 123b and the second concave side 123c of the battery cell 10 in which the three holes 22 are provided.

[0048] Gas discharged from the third sealing edge 123 due to factors such as abnormalities in the battery cell 10 is discharged through the gap between the +X side portion of the battery cell 10 and the -X side portion of the first protector 20 via the multiple holes 22. Therefore, the multiple holes 22 are an exhaust structure for discharging gas discharged from the third sealing edge 123 through the gap between the +X side portion of the battery cell 10 and the -X side portion of the first protector 20. Consequently, compared to a case where the multiple holes 22 are not provided, gas discharged from the third sealing edge 123 can be efficiently discharged through the gap between the +X side portion of the battery cell 10 and the -X side portion of the first protector 20.

[0049] The first concave edge 123b of each battery cell 10 is not bent and is positioned substantially perpendicular to the Y direction. As can be seen from Figure 4, the multiple holes 22 provided in each battery cell 10 and the first concave edge 123b of each 10 overlap each other at least partially in the X direction. As described above, the first film 12a and the second film 12b are most easily ruptured at the first concave edge 123b. Therefore, the fact that the multiple holes 22 provided in each battery cell 10 and the first concave edge 123b of each 10 overlap each other at least partially in the X direction makes it easier to efficiently discharge the gas emitted from the first concave edge 123b.

[0050] The second protector 40, like the first protector 20, defines multiple holes corresponding to the multiple holes 22. Therefore, the gas discharged from the fourth sealing edge 124 can be efficiently discharged through the gap between the -X side portion of the multiple battery cells 10 and the +X side portion of the second protector 40.

[0051] Figure 6 is a diagram illustrating the gas flow discharged from the first protruding edge 123a of each battery cell 10. As shown in Figure 6, the gas flow discharged from the first protruding edge 123a of the parallel cells 10a connected in series via the +X side lead group 15 is classified into the first flow F1 to the eighth flow F8, which will be described below.

[0052] The first flow F1 shows the gas flow due to the rupture of the first film 12a of the battery cell 10 on the -Y side of the parallel cell 10a on the -Y side in Figure 6. The second flow F2 shows the gas flow due to the rupture of the second film 12b of the battery cell 10 on the -Y side of the parallel cell 10a on the -Y side in Figure 6. The third flow F3 shows the gas flow due to the rupture of the first film 12a of the battery cell 10 on the +Y side of the parallel cell 10a on the -Y side in Figure 6. The fourth flow F4 shows the gas flow due to the rupture of the second film 12b of the battery cell 10 on the +Y side of the parallel cell 10a on the -Y side in Figure 6. The fifth flow F5 shows the gas flow due to the rupture of the first film 12a of the battery cell 10 on the -Y side of the parallel cell 10a on the +Y side in Figure 6. The sixth flow F6 shows the gas flow caused by the rupture of the second film 12b of the battery cell 10 on the -Y side of the parallel cell 10a on the +Y side in Figure 6. The seventh flow F7 shows the gas flow caused by the rupture of the first film 12a of the battery cell 10 on the +Y side of the parallel cell 10a on the +Y side in Figure 6. The eighth flow F8 shows the gas flow caused by the rupture of the second film 12b of the battery cell 10 on the +Y side of the parallel cell 10a on the +Y side in Figure 6.

[0053] The gas that flows through the first flow F1 flows along the positive electrode lead 13 drawn from the battery cell 10 on the -Y side of the parallel cell 10a on the -Y side and is discharged from the opening 21. The gas that flows through the eighth flow F8 flows along the negative electrode lead 14 drawn from the battery cell 10 on the +Y side of the parallel cell 10a on the +Y side and is discharged from the opening 21.

[0054] The gas that flows through the second flow F2 and the third flow F3 is blocked by the first confluence position 131 of the two positive electrode leads 13 drawn out from the parallel cell 10a on the -Y side, and flows from the first confluence position 131 to the +Z side and the -Z side. The gas that flows through the sixth flow F6 and the seventh flow F7 is blocked by the second confluence position 141 of the two negative electrode leads 14 drawn out from the parallel cell 10a on the +Y side, and flows from the second confluence position 141 to the +Z side and the -Z side.

[0055] The gas flowing through the fourth flow F4 flows along the positive electrode lead 13 drawn from the +Y side battery cell 10 of the parallel cell 10a on the -Y side, but is blocked by the first bending position 132 of the positive electrode lead 13 and flows from the first bending position 132 to the +Z side and -Z side. The gas flowing through the fifth flow F5 flows along the negative electrode lead 14 drawn from the -Y side battery cell 10 of the parallel cell 10a on the +Y side, but is blocked by the second bending position 142 of the negative electrode lead 14 and flows from the second bending position 142 to the +Z side and -Z side.

[0056] As can be seen from the explanation using Figure 6, in this embodiment, the gas that has flowed to the +Z side through the second flow F2, third flow F3, fourth flow F4, fifth flow F5, sixth flow F6, and seventh flow F7 can be discharged through the multiple holes 22. Therefore, the multiple holes 22 can function as a discharge structure for discharging not only the gas discharged from the first concave side 123b, but also the gas discharged from the first protruding side 123a.

[0057] In the example shown in Figure 4, no hole 22 is provided at a position overlapping the second concave edge 123c in the X direction. As described above, the first film 12a and the second film 12b are relatively resistant to tearing at the second concave edge 123c. Therefore, even without a hole 22 at a position overlapping the second concave edge 123c in the X direction, the gas discharged from the third sealing edge 123 can be discharged sufficiently efficiently. By not providing a hole 22 at a position overlapping the second concave edge 123c in the X direction, it is possible to maintain the strength of the first protector 20.

[0058] The number and position of the holes 22 are not limited to the example shown in Figure 4. For example, the holes 22 may be located offset from the position where they overlap with the first concave edge 123b of the first protector 20 in the X direction. Alternatively, the holes 22 may be located where they overlap with the second concave edge 123c of the first protector 20 in the X direction.

[0059] The discharge structure for discharging gas from the gap between the +X-side portions of the multiple battery cells 10 and the -X-side portion of the first protector 20 is not limited to holes provided in the first protector 20, but may also be a thin-walled portion provided in the first protector 20. By making the thickness in the X direction of the thin-walled portion of the first protector 20 thinner than the thickness in the X direction of the surrounding portion of the thin-walled portion of the first protector 20, the thin-walled portion of the first protector 20 becomes more easily melted by the gas discharged from the third sealing edge 123. As the thin-walled portion of the first protector 20 melts, holes are formed in the first protector 20 for discharging gas from the gap between the +X-side portions of the multiple battery cells 10 and the -X-side portion of the first protector 20.

[0060] Figure 7 is a front view of a modified battery cell 10A. The modified battery cell 10A is the same as the battery cell 10 according to the embodiment, except for the following points.

[0061] The modified battery cell 10A has a battery element 11 in the same manner as the battery cell 10 according to the embodiment. From the viewpoint shown in Figure 7, the battery element 11 is located behind and hidden by the cover material 16A on the +X side, which will be described later. The modified battery cell 10A further has a pair of cover materials 16A that cover both sides of the battery element 11 in the X direction. In the modified battery cell 10A, the outer casing material 12A is wound around the battery element 11 and the pair of cover materials 16A in the X direction. The inner surface of the +X side end of the outer casing material 12A in the X direction and the outer surface of the +X side cover material 16A in the X direction are joined to each other by sealing, for example, welding. The inner surface of the -X side end of the outer casing material 12A in the X direction and the outer surface of the -X side cover material 16A in the X direction are joined to each other by sealing, for example, welding. One of the positive lead 13A and the negative lead 14A is drawn out from the cover material 16A on the +X side, and the other of the positive lead 13A and the negative lead 14A is drawn out from the cover material 16A on the -X side.

[0062] As shown in Figure 7, when viewed from the X direction, the cover material 16A on the +X side has a roughly rectangular shape with a pair of short sides substantially parallel to the Y direction and a pair of long sides substantially parallel to the Z direction. As shown in Figure 7, the approximate center of the long side on the +Y side of the cover material 16A in the Z direction defines a notch 161A. Therefore, the sealing strength of the inner surface of the +X side portion of the outer casing material 12A around the X direction and the outer surface of the +X side cover material 16A around the X direction is weaker at the notch 161A than at the other parts. Consequently, if the internal pressure of the battery cell 10A increases due to factors such as an abnormality in the battery cell 10A, the +X side end of the outer casing material 12A and the +X side cover material 16A are prone to cracking at the notch 161A. Therefore, the notch 161A can function as a discharge structure for releasing gas generated from inside the battery cell 10A.

[0063] A protector corresponding to the first protector 20 according to the embodiment may also be located on the +X side of the modified battery cell 10A. Similar to the first protector 20 according to the embodiment, the protector located on the +X side of the modified battery cell 10A may define a hole corresponding to the hole 22 according to the embodiment. The hole in the protector and the notch 161A in the cover material 16A on the +X side may overlap each other at least partially in the X direction. By having the hole in the protector and the notch 161A in the cover material 16A on the +X side overlap each other at least partially in the X direction, gas discharged from the notch 161A can be efficiently discharged from the gap between the battery cell 10A and the protector.

[0064] The embodiments and modifications of the present invention have been described above with reference to the drawings, but these are merely examples of the present invention, and various other configurations can also be adopted. [Explanation of symbols]

[0065] 1 Battery module, 10, 10A Battery cell, 10a Parallel cell, 11 Battery element, 12, 12A Outer covering, 12a First film, 12b Second film, 121 First sealing edge, 121a First fixing tape, 122 Second sealing edge, 122a Second fixing tape, 123 Third sealing edge, 123a First protruding edge, 123b First concave edge, 123c Second concave edge, 124 Fourth sealing edge, 124a Second protruding edge, 124b Third concave edge, 124c Fourth concave edge, 124d Insulating tape, 125 First taper, 126 Second taper, 13, 13A Positive lead, 131 First junction position, 132 First bending position, 14, 14A Negative lead, 141 Second junction position, 142 Second bending position, 15 Lead group, 16A Lid material, 161A Notch, 20 First protector, 21 Opening, 22 Hole, 31 First long partition, 32 First short partition, 40 Second protector, 51 Second long partition, 52 Second short partition, 61 First plate, 62 Second plate, F1 First flow, F2 Second flow, F3 Third flow, F4 Fourth flow, F5 Fifth flow, F6 Sixth flow, F7 Seventh flow, F8 Eighth flow

Claims

1. Multiple battery cells, A protector located on at least one side of the plurality of battery cells, Equipped with, The battery module is characterized in that the protector has a discharge structure for discharging gas generated from the battery cell from between the battery cell and the protector.

2. The battery cell has other discharge structures for discharging gas generated from inside the battery cell. The battery module according to claim 1, wherein the discharge structure of the protector and the other discharge structure of the battery cell overlap each other at least partially.

3. The battery module according to claim 1 or 2, wherein the discharge structure is defined by at least one of a hole provided in the protector and a thin-walled portion provided in the protector.

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