Secondary battery module

Abstract

To provide a secondary electric module that can prevent pressure from being concentratedly applied to a specific surface of a module case when a plurality of cells expand.SOLUTION: A secondary electric module comprises a cell housing, a plurality of first battery cells, and a plurality of second battery cells. The cell housing has a first surface facing a first direction, and a second surface facing a second direction intersecting the first direction. Long-side surfaces of the plurality of first battery cells are adjacent in the first direction and face the first direction. Long-side surfaces of the plurality of second battery cells are adjacent in the second direction and face the second direction. The long-side surface of at least one first battery cell of the plurality of first battery cells is adjacent to short-side surfaces of the plurality of second battery cells in the first direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] FIELD An embodiment of the present invention relates to a secondary battery module. [Background technology]

[0002] Conventionally, a secondary battery module (hereinafter referred to as a module) has been known in which a plurality of secondary battery cells (hereinafter referred to as cells) are arranged and housed in a module case and electrically connected by conductive members. The outer container (cell can) of the prismatic cell is made of a material such as aluminum. In the module, the cells are often arranged side by side in one direction along the short side of the cell. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2021-163528 Summary of the Invention [Problem to be solved by the invention]

[0004] Depending on the charge / discharge conditions and storage environment, gas may be generated inside the cells. This gas may increase the internal pressure of the cells, causing the long sides of multiple cells in the module to expand. When the long sides of multiple cells expand, pressure is concentrated on specific surfaces of the module case that covers the cells, which may weaken the module.

[0005] The problem to be solved by the present invention is to provide a secondary electric module that can prevent pressure from being concentrated on a specific surface of the module case when a plurality of cells expand. [Means for solving the problem]

[0006] To achieve the above object, a secondary battery module according to an embodiment of the present invention includes a cell housing, a plurality of first battery cells, and a plurality of second battery cells. The cell housing has a first inner surface facing a first direction and a second inner surface facing a second direction intersecting the first direction. The long sides of the plurality of first battery cells are adjacent to each other in the first direction and face the first direction. The long sides of the plurality of second battery cells are adjacent to each other in the second direction and face the second direction. The long side of at least one first battery cell among the plurality of first battery cells is adjacent to a short side of each of the plurality of second battery cells in the first direction. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is an exploded perspective view of a secondary battery module according to a first embodiment. [Figure 2] FIG. 2 is a perspective view showing a part of the case of the secondary battery module of the first embodiment. [Figure 3] FIG. 3 is a perspective view showing a part of the case of the secondary battery module of the first embodiment. [Figure 4] FIG. 4 is a perspective view showing a battery cell in the secondary battery module of the first embodiment before it expands inside the case. [Figure 5] FIG. 5 is a perspective view showing the assembled secondary battery module of the first embodiment. [Figure 6] FIG. 6 is a perspective view showing a battery cell that is swollen inside a case in the secondary battery module of the first embodiment. [Figure 7] FIG. 7 is a perspective view showing a battery cell that is swollen inside a case in a secondary battery module according to a comparative example of the first embodiment. [Figure 8] FIG. 8 is an exploded perspective view of the secondary battery module of the second embodiment. [Figure 9] FIG. 9 is a perspective view showing an assembled secondary battery module according to the second embodiment. [Figure 10]FIG. 10 is a perspective view showing a battery cell that is swollen inside a case in a secondary battery module according to the second embodiment. [Figure 11] FIG. 11 is a perspective view showing another arrangement of first battery cells and second battery cells of the secondary battery module of the second embodiment. [Figure 12] FIG. 12 is a perspective view showing another arrangement of first battery cells and second battery cells of the secondary battery module of the second embodiment. [Figure 13] FIG. 13 is a perspective view showing another arrangement of first battery cells and second battery cells of the secondary battery module of the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] (First embodiment) Hereinafter, embodiments of the secondary battery module of the present invention will be described in detail with reference to the accompanying drawings. The configuration of the embodiment described below, and the actions and results (effects) brought about by the configuration are merely examples, and are not limited to the following description. Note that in this specification, ordinal numbers are used only to distinguish between parts and components, and do not indicate order or priority.

[0009] The structure of a secondary battery module 1 according to a first embodiment of the present invention will be described with reference to Fig. 1. Fig. 1 is an exploded perspective view of the secondary battery module 1 according to the first embodiment.

[0010] In the following description, an X-axis, Y-axis, and Z-axis Cartesian coordinate system is defined. The short-side direction of the case is defined as the X-axis direction, the long-side direction of the case is defined as the Y-axis direction, and the height direction of the case is defined as the Z-axis direction. The X-axis direction may also be referred to as the depth direction. The Y-axis direction may also be referred to as the left-right direction. Note that the X-axis, Y-axis, and Z-axis Cartesian coordinate system is a coordinate system used for convenience, and embodiments of the present invention can also be applied to secondary battery modules to which this coordinate system cannot be applied.

[0011] The secondary battery module 1 of this embodiment includes a case 10 having a pair of short side surfaces 1011a facing in the left-right direction and a pair of long side surfaces 1012a1, 1012a2, and 1012a3 facing in a depth direction intersecting the left-right direction, and a plurality of battery cells 12 housed in the case 10, each having a long side surface 1231 and a short side surface 1232. The case 10 is an example of a cell housing. The pair of short side surfaces 1011a are an example of a first inner surface. The pair of long side surfaces 1012a1, 1012a2, and 1012a3 are an example of a second inner surface. The left-right direction is an example of a first direction. The depth direction is an example of a second direction.

[0012] For example, the secondary battery module 1 forms a series connection structure in which a plurality of battery cells 12 are electrically connected in series. The battery cells 12 are also electrically connected to one another via a plurality of bus bars 13. The power of the plurality of battery cells 12, i.e., the power of the secondary battery module 1, can be output to an external connector (not shown) via the bus bars 13 and a connector (not shown). The battery cells 12 and the bus bars 13 will be described in detail later.

[0013] The secondary battery module 1 is installed in various devices, machines, equipment, etc. and used as a power source for these various devices, machines, and equipment. For example, the secondary battery module 1 can be used as a mobile power source for automobiles, bicycles (mobile objects), etc., as well as a stationary power source for, for example, a point-of-sale (POS) system. Furthermore, various devices can be equipped with a plurality of secondary battery modules 1 shown in this embodiment connected in series or parallel as a set. The number and arrangement of the battery cells 12 and bus bars 13 included in the secondary battery module 1 are not limited to those disclosed in this embodiment. The secondary battery module 1 is also referred to as a battery pack, a battery device, etc. The battery cells 12 are also referred to as cells, batteries, etc.

[0014] The case 10 is configured in the shape of a rectangular parallelepiped box with one end (top end) open. The case 10 is made of an electrically insulating material. Examples of materials that can be used to form the case 10 include resins such as polyphenylene ether, polycarbonate, and polybutylene terephthalate.

[0015] The case 10 is composed of a box portion 101 and a cover 102. The box portion 101 has a pair of side walls 1011 facing each other in the longitudinal direction (Y-axis direction) of the case 10, a pair of side walls 1012 facing each other in the lateral direction (X-axis direction) of the case 10, and a bottom plate 1013. The pair of side walls 1011, the pair of side walls 1012, and the bottom plate 1013 are integrally formed.

[0016] Each of the pair of side walls 1011 has a short side surface 1011a. The short side surface 1011a faces the left-right direction (Y-axis direction). The pair of side walls 1012 has long side surfaces 1012a1, 1012a2, and 1012a3. Each of the long side surfaces 1012a1, 1012a2, and 1012a3 faces the depth direction (X-axis direction). The long side surface 1012a2 protrudes further in the X-axis direction than the long side surfaces 1012a1 and 1012a3.

[0017] The cover 102 is configured as a substantially rectangular plate and covers the portion of the case 10 that is open in the +Z direction. The case 10 and the cover 102 are joined to each other by, for example, welding, etc. This prevents liquid, gas, etc. from leaking from the joined portion. A top wall portion 1021 of the cover 102 is formed with a plurality of holes 1022 through which the positive electrode terminal 124 and the negative electrode terminal 125 pass.

[0018] The battery cells 12 are made of a metal material such as aluminum. The battery cells 12 are of a so-called prismatic can type and may also be referred to as can cells. The battery cells 12 are, for example, configured as lithium-ion secondary batteries. Lithium-ion secondary batteries are a type of non-aqueous electrolyte secondary battery, in which lithium ions in the electrolyte are responsible for electrical conduction. Examples of positive electrode materials include lithium manganese composite oxide, lithium nickel composite oxide, lithium cobalt composite oxide, lithium nickel cobalt composite oxide, lithium manganese cobalt composite oxide, spinel-type lithium manganese nickel composite oxide, and lithium phosphate oxide with an olivine structure. Examples of negative electrode materials include oxide materials such as lithium titanate (LTO) and oxide materials such as niobium composite oxide. The electrolyte (e.g., electrolytic solution) is a mixture of a lithium salt such as a fluorine-based complex salt (e.g., LiBF4, LiPF6), and an organic solvent such as ethylene carbonate, propylene carbonate, diethyl carbonate, ethyl methyl carbonate, or dimethyl carbonate, either singly or in combination. The battery cells 12 may be other secondary batteries (storage batteries, rechargeable batteries) such as nickel-metal hydride batteries, nickel-cadmium batteries, and lead-acid batteries.

[0019] The battery cell 12 has, for example, a housing 123 and positive and negative terminals 124 and 125 as electrodes. The housing 123 is configured in a thin, flat, and generally rectangular parallelepiped shape. The positive and negative terminals 124 and 125 are provided on an upper surface 1233 of the housing 123.

[0020] As shown in FIG. 1 , within the case 10, the positions of the positive electrode terminal 124 and the negative electrode terminal 125 of one battery cell 12 are opposite to those of another battery cell 12 adjacent to the one battery cell 12. For example, the positions of the positive electrode terminal 124 and the negative electrode terminal 125 of one battery cell 12 in the long side direction are opposite to those of another battery cell 12 adjacent to the one battery cell 12. The positive electrode terminals 124 and the negative electrode terminals 125 of each of the multiple battery cells 12 all protrude in the +Z direction. Here, "adjacent" means that the battery cells 12 are close enough to contact each other when not inflated, or that the battery cells 12 are not in contact with each other when not inflated, but are close enough to contact each other when they are expanded by a certain amount. For the sake of concreteness, this embodiment will use a case where the battery cells abut each other as an example of adjacency.

[0021] When gas is generated inside the battery cells 12, each battery cell 12 swells in the Y-axis direction, which is the direction in which the long side surface 1231 of the battery cell 12 faces. In contrast, the battery cell 12 does not swell in the X-axis direction, which is the forward and backward directions in FIG. 7 . The size of the first battery cell 12a and the second battery cell 12b in the swelled state is, for example, a length such that the length in the short side direction of the short side surface 1232 of the first battery cell 12a or the second battery cell 12b is 1.5 times the length before swell. The size of the first battery cell 12a and the second battery cell 12b in the swelled state is not limited to this, and may be any size that applies sufficient pressure to the side wall 1011 or the side wall 1012 of the case 10 when the first battery cell 12a and the second battery cell 12b are housed in the case 10.

[0022] The case 10 accommodates, for example, nine battery cells 12. As shown in FIG. 1, the nine battery cells 12 are classified into three first battery cells 12a and six second battery cells 12b depending on the orientation in which they are accommodated within the case 10. In this embodiment, the long side surfaces 1231a of the three first battery cells 12a abut against each other in the left-right direction (Y-axis direction) and face the left-right direction. The long side surfaces 1231b of the three second battery cells 12b abut against each other in the depth direction (X-axis direction) and face the depth direction. The short side surfaces 1232a of the three first battery cells 12a face the X-axis direction. The short side surfaces 1232b of the three second battery cells 12b face the Y-axis direction.

[0023] The long side surface 1231a of at least one of the three first battery cells 12a abuts against the short side surfaces 1232b of each of the three second battery cells 12b in the left-right direction (Y-axis direction). In the following description, of the nine battery cells 12 housed in the case 10, three adjacent battery cells 12 whose long sides face the same direction will be referred to as cell columns 12A, 12B, and 12C, in order from the -Y direction side. Each of the three first battery cells 12a belonging to cell column 12B is sandwiched between three second battery cells 12b belonging to each of the two cell columns 12A and 12C in the left-right direction.

[0024] The secondary battery module 1 includes a plurality of bus bars 13 that electrically connect the plurality of battery cells 12 in series or in parallel. The bus bars 13 are, for example, made of aluminum or an aluminum alloy and formed into a rectangular flat plate. The bus bars 13 are connected, for example, by welding to the positive electrode terminals 124 and negative electrode terminals 125 of the battery cells 12 that pass through the plurality of holes 1022. In this embodiment, the plurality of battery cells 12 are connected in series by the bus bars 13.

[0025] FIG. 2 is a perspective view showing a portion of the case 10 of the secondary battery module 1 of the first embodiment. More specifically, FIG. 2 shows the box portion 101 of the case 10 of the secondary battery module 1. As shown in FIG. 2, the box portion 101 of the case 10 has a plurality of partition walls 1015 that separate the plurality of battery cells 12. The partition walls 1015 are disposed on the bottom plate 1013 of the box portion 101. The partition walls 1015 extend in the direction in which the short side surface 1232a or the short side surface 1232b of the battery cell 12 housed in the box portion 101 faces. More specifically, the partition wall 1015 disposed in the portion of the bottom plate 1013 where the first battery cell 12a is housed extends in the depth direction (X-axis direction). The partition wall 1015, which is disposed in the portion of the bottom plate 1013 where the second battery cell 12b is housed, extends in the left-right direction (Y-axis direction). The partition wall 1015 protrudes in the +Z direction from the bottom plate 1013. The length of the partition wall 1015 in the height direction (Z-axis direction) is sufficiently smaller than the length of the box portion 101 in the height direction (Z-axis direction) and the length of the battery cell 12 housed in the box portion 101 in the height direction (Z-axis direction).

[0026] As described above, the long side surface 1012a2 of the box portion 101 protrudes in the X-axis direction further than the long side surfaces 1012a1 and 1012a3. Therefore, at the end of the case 10 in the X-axis direction, four spaces S are present that are separated from the interior of the box portion 101 by the side walls 1012. These spaces S can be used as spaces for accommodating the heads of screws when fastening the screws to the side walls 1012 to connect the secondary battery module 1 to an external device, etc. Note that the box portion 101 may have a shape that does not include the spaces S. When the space S is not provided in the box portion 101, the box portion 101 forms a substantially rectangular parallelepiped shape whose length in the X-axis direction coincides with the length of the long side surfaces 1012a2 in the X-axis direction.

[0027] FIG. 3 is a perspective view showing a portion of the case 10 of the secondary battery module 1 of the first embodiment. More specifically, FIG. 3 shows the cover 102 of the case 10 of the secondary battery module 1. As shown in FIG. 3, the cover 102 of the case 10 has a plurality of partition walls 1024 that separate the plurality of battery cells 12. The partition walls 1024 are disposed on the top wall 1021 of the cover 102. The partition walls 1024 extend in the direction in which the short side surface 1232a or the short side surface 1232b of the battery cell 12 that fits into the cover 102 faces. More specifically, the partition wall 1024 disposed in the portion of the top wall 1021 that fits with the first battery cell 12a extends in the depth direction (X-axis direction). The partition wall 1024, which is disposed in the portion of the top wall 1021 that houses the second battery cell 12b, extends in the left-right direction (Y-axis direction). The partition wall 1024 protrudes in the -Z direction from the top wall 1021. The length of the partition wall 1024 in the height direction (Z-axis direction) is sufficiently smaller than the length of the cover 102 in the height direction and the length of the battery cell 12 that fits into the cover 102 in the height direction.

[0028] FIG. 4 is a perspective view showing a battery cell 12 in the secondary battery module 1 of the first embodiment before it expands inside the case 10. As shown in FIG. 4, the battery cell 12 has a substantially rectangular parallelepiped shape when no gas is generated inside. When gas is generated inside the battery cell 12, the long side surface 1231 of the battery cell 12 expands in the direction of the arrow (X-axis direction) in FIG. 4. The expanded volume of the battery cell 12 increases the closer it is to the center of the long side surface 1231. Meanwhile, the short side surface 1232, top surface 1233, and bottom surface 1234 of the battery cell 12 are slightly recessed toward the center of the battery cell 12. The expanded state of the battery cell 12 is not shown in the figure.

[0029] Fig. 5 is a perspective view showing the assembled secondary battery module 1 of the first embodiment. As shown in Fig. 5, when the secondary battery module 1 is assembled, the case 10, battery cells 12, and bus bars 13 are integrated. The bus bars 13 are fixed to the top wall portion 1021 of the cover 102. Note that the battery cells 12 are not shown in Fig. 5.

[0030] (Actions and effects of secondary battery module) Next, the effects of the secondary battery module 1 will be described with reference to FIG. 6. FIG. 6 is a perspective view showing a battery cell 12 that has expanded inside the case 10 in the secondary battery module 1 of the first embodiment. When gas is generated inside the battery cell 12, as shown in FIG. 6, the long side surface 1231 of each of the multiple battery cells 12 expands toward the outside of the battery cell 12. More specifically, the long side surface 1231a of the three first battery cells 12a belonging to the cell series 12B expands in the Y-axis direction. Meanwhile, the long side surfaces 1231b of the six second battery cells 12b belonging to the cell series 12A and 12C expand in the X-axis direction. Due to the expansion of the first battery cells 12a and the second battery cells 12b described above, the battery cells 12 as a whole expand in both the X-axis and Y-axis directions.

[0031] In the above-described embodiment, the secondary battery module 1 includes a case 10, a plurality of first battery cells 12a, and a plurality of second battery cells 12b. The case 10 has a short side surface 1011a facing the left-right direction (Y-axis direction) and long side surfaces 1012a1, 1012a2, and 1012a3 facing the depth direction (X-axis direction) intersecting the left-right direction. The long side surfaces 1231a of the plurality of first battery cells 12a are adjacent to each other in the left-right direction and also face the left-right direction. The long side surfaces 1231b of the plurality of second battery cells 12b are adjacent to each other in the depth direction and also face the depth direction. The long side surface 1231a of at least one first battery cell 12a among the plurality of first battery cells 12a is adjacent to a short side surface 1232b of each of the plurality of second battery cells 12b in the left-right direction.

[0032] With the above-described configuration, the stress that the case 10 receives from the first battery cell 12a and the second battery cell 12b is distributed to each of the short side surface 1011a and the long side surfaces 1012a1, 1012a2, and 1012a3 of the case 10. In other words, the configuration of the multiple battery cells 12 can prevent pressure from being concentrated on a specific surface of the case 10 when the multiple battery cells 12 expand.

[0033] Furthermore, the long side surface 1231a of at least one of the three first battery cells 12a abuts against the short side surfaces 1232b of each of the three second battery cells 12b in the left-right direction (Y-axis direction). The short side surfaces 1232b of the second battery cells 12b are less deformed than the long side surfaces 1231 of the first battery cells 12a. Therefore, in the above-described configuration, the second battery cells 12b can prevent the first battery cells 12a belonging to the cell row 12B from expanding in the Y-axis direction.

[0034] Furthermore, each of the three first battery cells 12a belonging to cell column 12B is sandwiched in the left-right direction (Y-axis direction) by three second battery cells 12b belonging to cell columns 12A and 12C, respectively. Therefore, in the above-described configuration, the second battery cells 12b can further prevent the first battery cells 12a belonging to cell column 12B from expanding in the Y-axis direction.

[0035] (Comparative Example) Next, a secondary battery module 1a according to a comparative example of the first embodiment will be described with reference to Fig. 7. Fig. 7 is a perspective view showing a battery cell 12 bulging inside a case (not shown) in a secondary battery module 1a according to a comparative example of the first embodiment. As shown in Fig. 7, the nine battery cells 12 in the comparative example are arranged linearly in the Y-axis direction with the long side surfaces 1231 of the nine battery cells 12 facing each other. The long side surfaces 1231 of the nine battery cells 12 face the Y-axis direction.

[0036] In the above-described configuration, gas is generated inside the battery cells 12, and each of the battery cells 12 bulges in the Y-axis direction, which is the direction in which the long side surface 1231 of each battery cell 12 faces, and the battery cells 12 abut against each other. In contrast, they do not bulge in the depth direction (X-axis direction) in FIG. 7. That is, the bulging directions of each battery cell 12 are concentrated in one direction (Y-axis direction), and the nine battery cells 12 as a whole bulge in the concentrated direction (Y-axis direction) to a greater extent than the bulging size of each individual battery cell 12. For this reason, the case in the comparative example is prone to stress on the inner surface facing the bulging direction (Y-axis direction) of each battery cell 12.

[0037] On the other hand, in the secondary battery module 1 of embodiment 1, the expansion directions of the battery cells 12 are not concentrated in one direction but are dispersed in two directions (X-axis direction and Y-axis direction). Therefore, in the secondary battery module 1 of embodiment 1, the expansion directions of the battery cells 12 are prevented from concentrating in one direction more than in the secondary battery module 1a of the comparative example, and thus pressure can be prevented from being concentrated on a specific surface of the case 10.

[0038] (Second embodiment) Next, a secondary battery module 1A according to a second embodiment will be described with reference to Fig. 8 to Fig. 10. The secondary battery module 1A according to the second embodiment is a modified version of the configuration of the secondary battery module 1 according to the first embodiment described with reference to Fig. 1, and a description of the configuration similar to that of the first embodiment will be omitted.

[0039] FIG. 8 is an exploded perspective view of a secondary battery module 1A according to the second embodiment. FIG. 9 is a perspective view showing the assembled secondary battery module 1A according to the second embodiment. As shown in FIGS. 8 and 9, the secondary battery module 1A according to the second embodiment has a case 10A (a box portion 101A and a cover 102A) that is different in shape from the case 10. Furthermore, the arrangement of the battery cells 12 housed in the box portion 101A differs from that of the secondary battery module 1. More specifically, nine battery cells 12 are housed in the case 10A, and each of the three second battery cells 12b belonging to the cell string 12B is sandwiched in the left-right direction (the Y-axis direction) between three first battery cells 12a belonging to each of the two cell strings 12A and 12C. In this case, the number of second battery cells 12b sandwiched between the three first battery cells 12a belonging to each of the two cell strings 12A and 12C is an odd number. In other words, the number of second battery cells 12b sandwiched between the plurality of first battery cells 12a is odd. The shape of the case 10A is shaped to match the arrangement of the above-mentioned battery cells 12. The two spaces S are separated from the interior of the box portion 101 by a side wall 1012.

[0040] (Action and effect) FIG. 10 is a perspective view showing a battery cell 12 that is bulging inside the case 10A of the secondary battery module 1A of the second embodiment. When gas is generated inside the battery cell 12, as shown in FIG. 10, the long side surfaces 1231a, 1231b of each of the multiple battery cells 12 bulge toward the outside of the battery cell 12. More specifically, the long side surfaces 1231a of the six first battery cells 12a belonging to the cell series 12A and 12C bulge in the Y-axis direction. Meanwhile, the long side surfaces 1231b of the three second battery cells 12b belonging to the cell series 12B bulge in the X-axis direction. Due to the above-described expansion of the first battery cells 12a and second battery cells 12b, the battery cells 12 as a whole bulge in both the X-axis and Y-axis directions.

[0041] In the above-described embodiment, the secondary battery module 1A includes a case 10A, a plurality of first battery cells 12a, and a plurality of second battery cells 12b. The case 10A has a short side surface 1011a facing the left-right direction (Y-axis direction) and long side surfaces 1012a1, 1012a2, and 1012a3 facing the depth direction (X-axis direction) intersecting the left-right direction. The long side surfaces 1231a of the plurality of first battery cells 12a are adjacent to each other in the left-right direction and also face the left-right direction. The long side surfaces 1231b of the plurality of second battery cells 12b are adjacent to each other in the depth direction and also face the depth direction. The long side surface 1231a of at least one first battery cell 12a among the plurality of first battery cells 12a is adjacent to a short side surface 1232b of each of the plurality of second battery cells 12b in the left-right direction.

[0042] With the above-described configuration, when the first battery cells 12a and the second battery cells 12b expand, the stress that the case 10A receives from the first battery cells 12a and the second battery cells 12b is distributed to each of the short side surface 1011a and the long side surfaces 1012a1, 1012a2, and 1012a3 of the case 10A. In other words, the secondary battery module 1A can prevent pressure from being concentrated on a specific surface of the case 10A when the multiple battery cells 12 expand.

[0043] Furthermore, the long side surface 1231a of at least one of the six first battery cells 12a abuts against the short side surfaces 1232b of each of the three second battery cells 12b in the left-right direction (Y-axis direction). The short side surfaces 1232b of the second battery cells 12b are less deformed than the long side surfaces 1231 of the first battery cells 12a. Therefore, in the above-described configuration, the second battery cells 12b can prevent the first battery cells 12a belonging to the cell rows 12A and 12C from expanding in the Y-axis direction.

[0044] In addition, the number of second battery cells 12b sandwiched between the plurality of first battery cells 12a is an odd number. With this structure, the battery cells 12 belonging to each of the cell strings 12A, 12B, and 12C can be connected in series with each other via the bus bars 13.

[0045] (Variation 1) In the secondary battery module 1 of this embodiment, the first battery cell 12a and the second battery cell 12b are in contact with each other when the cells are not expanded. Alternatively, the first battery cell 12a and the second battery cell 12b may be arranged at a fixed distance from each other when the cells are not expanded, and the first battery cell 12a and the second battery cell 12b may come into contact with each other when the cells are expanded by a certain amount or more. More specifically, for example, the multiple first battery cells 12a may be arranged such that the long side surfaces 1231a of each first battery cell 12a are not in contact with each other in the left-right direction (Y-axis direction) but are spaced apart and face the left-right direction. Furthermore, the multiple second battery cells 12b may be arranged such that the long side surfaces 1231b of each second battery cell 12b are not in contact with each other in the depth direction (X-axis direction) but are spaced apart and face the depth direction. Furthermore, at least one of the plurality of first battery cells 12a may be arranged so that the long side surface 1231a of the first battery cell 12a is not in contact with the short side surfaces 1232b of the plurality of second battery cells 12b in the left-right direction but is spaced a certain distance apart.

[0046] Even in the above-described configuration, the expansion of the first battery cell 12a and the second battery cell 12b causes the battery cells 12 as a whole to expand in the X-axis direction and the Y-axis direction. As a result, the stress that the case 10 receives from the multiple first battery cells 12a and the multiple second battery cells 12b is distributed to each of the short side surface 1011a and the long side surfaces 1012a1, 1012a2, and 1012a3 facing the depth direction (X-axis direction) of the surface of the case 10. In other words, the secondary battery module 1 can prevent pressure from being concentrated on a specific surface of the case 10 when the multiple battery cells 12 expand.

[0047] (Variation 2) Next, a secondary battery module 1B having a different configuration from the secondary battery module 1 of the first embodiment will be described with reference to Fig. 11. The secondary battery module 1B in Modification 2 is obtained by partially modifying the configuration of the secondary battery module 1 of the first embodiment described with reference to Fig. 1, and a description of the same configuration as in the first embodiment will be omitted.

[0048] FIG. 11 is a perspective view showing a different arrangement of first battery cells 12a and second battery cells 12b in the secondary battery module 1 of the second embodiment. As shown in FIG. 11, in the secondary battery module 1B of the second modification, the arrangement of the battery cells 12 housed in the box portion (not shown) is different from that of the secondary battery module 1. More specifically, thirteen battery cells 12 are housed in the case (not shown), and each of the three first battery cells 12a belonging to the cell string 12B is sandwiched in the left-right direction (Y-axis direction) between five first battery cells 12a belonging to each of the two cell strings 12A and 12C. The shape of the case 10 (not shown) is adapted to the arrangement of the battery cells 12 described above. Note that the space S does not exist in the secondary battery module 1B of the second modification.

[0049] In the secondary battery module 1B of Modification 2, as in the secondary battery module 1 in First Embodiment 1, when the multiple first battery cells 12a and multiple second battery cells 12b expand, the stress that the case receives from the three first battery cells 12a and ten second battery cells 12b is distributed to each of the short side surfaces and the long side surfaces facing the depth direction (X-axis direction) of the case. In other words, the secondary battery module 1B can prevent pressure from being concentrated on a specific surface of the case when the multiple battery cells 12 expand.

[0050] In addition, in the Y-axis direction, the first battery cell 12a belonging to cell series 12B is sandwiched at both ends by the second battery cells 12b belonging to cell series 12A and 12C. As a result, the second battery cells 12b prevent the first battery cells 12a belonging to cell series 12B from expanding in the Y-axis direction.

[0051] (Variation 3) Next, a secondary battery module 1C having a different configuration from the secondary battery module 1A of the second embodiment will be described with reference to Fig. 12. The secondary battery module 1C in Modification 3 is obtained by partially modifying the configuration of the secondary battery module 1A of the second embodiment described with reference to Fig. 8, and description of the same configuration as the second embodiment will be omitted.

[0052] FIG. 12 is a perspective view showing a different arrangement of the first battery cells 12a and second battery cells 12b of the secondary battery module 1A of the second embodiment. As shown in FIG. 12, in the secondary battery module 1C of the third modification, the arrangement of the battery cells 12 housed in the box portion (not shown) is different from that of the secondary battery module 1A. More specifically, eleven battery cells 12 are housed in the case (not shown), and five second battery cells 12b belonging to the cell string 12B are sandwiched in the Y-axis direction between three first battery cells 12a belonging to each of the two cell strings 12A and 12C. In this case, the number of second battery cells 12b belonging to the cell string 12B is an odd number. In other words, the number of second battery cells 12b sandwiched between the multiple first battery cells 12a is an odd number. Furthermore, the shape of the case (not shown) is shaped to match the arrangement of the battery cells 12 described above. Note that the space S does not exist in the secondary battery module 1C of the third modification.

[0053] In the secondary battery module 1C of Modification 3, as in the secondary battery module 1A of the second embodiment, when the first battery cells 12a and the second battery cells 12b expand, the stress that the case receives from the six first battery cells 12a and the five second battery cells 12b is distributed to each of the short side and long side of the case. In other words, the secondary battery module 1C can prevent pressure from being concentrated on a specific surface of the case when the battery cells 12 expand.

[0054] In addition, in the Y-axis direction, the second battery cell 12b belonging to the cell series 12B is sandwiched at both ends by the first battery cells 12a belonging to the cell series 12A and 12C. As a result, the second battery cell 12b prevents the first battery cells 12a belonging to the cell series 12A and 12C from expanding in the Y-axis direction.

[0055] In addition, the number of second battery cells 12b sandwiched between the plurality of first battery cells 12a is an odd number. With this structure, the battery cells 12 belonging to each of the cell strings 12A, 12B, and 12C can be connected in series with each other via the bus bars 13.

[0056] (Variation 4) Next, a secondary battery module 1D having a different configuration from the secondary battery module 1A of the second embodiment will be described with reference to Fig. 13. The secondary battery module 1D in Modification 4 is obtained by partially modifying the configuration of the secondary battery module 1A of the second embodiment described with reference to Fig. 8, and description of the same configuration as the second embodiment will be omitted.

[0057] FIG. 13 is a perspective view showing a different arrangement of the first battery cells 12a and second battery cells 12b of the secondary battery module 1A of the second embodiment. As shown in FIG. 13, in the secondary battery module 1D of the fourth modification, the arrangement of the battery cells 12 housed in the box portion (not shown) is different from that of the secondary battery module 1A. More specifically, eight battery cells 12 are housed in the case (not shown), and a cell string 12B consisting of five second battery cells 12b is adjacent to a cell string 12A consisting of three first battery cells 12a in the Y-axis direction. Furthermore, there is no cell string 12C. The shape of the case 10 (not shown) is shaped to match the arrangement of the battery cells 12 described above. Note that the space S does not exist in the secondary battery module 1D of the third modification.

[0058] In the secondary battery module 1D of Modification 4, similarly to the secondary battery module 1A of the second embodiment, when the multiple first battery cells 12a and multiple second battery cells 12b expand, the stress that the case 10 receives from the three first battery cells 12a and five second battery cells 12b is distributed to each of the short side and long side of the case. In other words, the secondary battery module 1D can prevent pressure from being concentrated on a specific surface of the case when the multiple battery cells 12 expand.

[0059] Furthermore, the long side surface 1231a of at least one of the three first battery cells 12a abuts against the short side surfaces 1232b of the five second battery cells 12b in the left-right direction (Y-axis direction). As a result, the second battery cells 12b prevent the first battery cells 12a belonging to the cell row 12A from expanding in the Y-axis direction.

[0060] (Variation 5) The battery cells 12 are not limited to rectangular can types, and may be formed, for example, in a generally cylindrical shape with a chamfered side. The battery cells 12 may also have an irregularly shaped housing such as a pouch.

[0061] Although several embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0062] 1, 1a, 1A, 1B, 1C, 1D Secondary battery module 10, 10A case 12a 1st battery cell 12b Second battery cell 12A, 12B, 12C cell rows 101, 101A Hakobe 1011a short side 1012a1, 1012a2, 1012a3 long side

Claims

1. a cell housing having a first inner surface facing a first direction and a second inner surface facing a second direction intersecting the first direction; a plurality of first battery cells and a plurality of second battery cells housed in the cell housing, each having a long side and a short side; Equipped with the long side surfaces of the first battery cells are adjacent to each other in the first direction and face the first direction; the long side surfaces of the second battery cells are adjacent to each other in the second direction and face the second direction; the long side surface of at least one of the plurality of first battery cells is adjacent to the short side surface of each of the plurality of second battery cells in the first direction; Secondary battery module.

2. the long side surface of at least one of the plurality of first battery cells abuts against the short side surfaces of each of the plurality of second battery cells in the first direction; the second battery cells prevent the first battery cells from expanding in the first direction; The secondary battery module according to claim 1 .

3. the long side surface of at least one of the plurality of first battery cells abuts against the first inner surface of the cell casing in the first direction; the long side surface of at least one of the second battery cells abuts against the second inner surface of the cell casing in the second direction; stress that the cell casing receives from the first battery cell and the second battery cell is distributed to the first inner surface and the second inner surface of the cell casing, respectively; The secondary battery module according to claim 1 .

4. each of the second battery cells is sandwiched between the first battery cells in the first direction; the number of the second battery cells sandwiched between the plurality of first battery cells is an odd number; The secondary battery module according to claim 1 .

5. Each of the first battery cells is sandwiched between the second battery cells in the first direction. The secondary battery module according to claim 2 .

Images