Battery module

Abstract

A battery module (100) comprises a battery cell (110), and a flexible substrate (123) that has a fuse (123f) electrically connected to the battery cell (110).

Description

Battery module

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

[0002] In recent years, various battery modules have been developed, each of which includes battery cells.

[0003] Patent Documents 1 and 2 describe a flexible printed circuit (FPC). The FPC has a conductive pattern. The conductive pattern includes a fuse portion.

[0004] JP 2017-10859 A JP 2007-317990 A

[0005] A fuse may be electrically connected to a battery cell. However, when a fuse provided on a rigid substrate such as a PCB (printed circuit board) is electrically connected to a battery cell, it may be difficult to improve the degree of freedom in the shape of the fuse.

[0006] One example of an object of the present invention is to improve the degree of freedom in the shape of a fuse that is electrically connected to a battery cell. Other objects of the present invention will become apparent from the description of this specification.

[0007] One aspect of the present invention is as follows: 1. A battery module comprising: a battery cell; and a flexible substrate having a fuse electrically connected to the battery cell. 2. The battery module described in 1., further comprising a support to which the flexible substrate is attached, the support defining an overlapping region that at least partially overlaps the fuse and an enclosing region that at least partially surrounds the overlapping region, and the thermal conductivity of the overlapping region is lower than that of the enclosing region. 3. The battery module described in 2., in which the overlapping region defines a hole penetrating the support.

[0008] According to the above aspect of the present invention, it is possible to improve the degree of freedom in the shape of the fuse electrically connected to the battery cell.

[0009] 2 is a perspective view of a battery module according to an embodiment; FIG. 3 is a front view of a part of a battery module according to an embodiment; FIG. 4 is a cross-sectional view taken along line AA of FIG. 2; and FIG.

[0010] Hereinafter, embodiments and modifications of the present invention will be described with reference to the drawings. In all the drawings, like components are designated by like reference numerals, and descriptions thereof will be omitted as appropriate.

[0011] Fig. 1 is a perspective view of a battery module 100 according to an embodiment. Fig. 2 is a front view of a portion of the battery module 100 according to an embodiment. Fig. 3 is a cross-sectional view taken along line A-A in Fig. 2. For the sake of explanation, Fig. 1 has removed a plurality of voltage detection terminals 122, a plurality of flexible substrates 123, and a plurality of voltage detection wires 124 shown in Fig. 2.

[0012] For the purpose of explanation, the X, Y, and Z directions are shown in each figure. The X direction indicates the front-to-rear direction of the battery module 100. The Y direction is perpendicular to the X direction. The Y direction indicates the left-to-right direction of the battery module 100. The Z direction is perpendicular to both the X and Y directions. The Z direction indicates the up-down direction of the battery module 100. The arrows pointing to the X direction, the Y direction, and the Z direction indicate the rear, left, and up directions of the battery module 100, respectively. In Figures 2 and 3, a white circle with an X indicating the Z direction or the X direction indicates that the arrow pointing in the direction indicated by the white circle extends from the front to the back of the page. Hereinafter, as necessary, the tip side of the arrow indicating the X direction will be referred to as the +X side, the opposite side of the tip of the arrow indicating the X direction will be referred to as the -X side, the tip side of the arrow indicating the Y direction will be referred to as the +Y side, the opposite side of the tip of the arrow indicating the Y direction will be referred to as the -Y side, the tip side of the arrow indicating the Z direction will be referred to as the +Z side, and the opposite side of the tip of the arrow indicating the Z direction will be referred to as the -Z side. The relationship between the X direction, Y direction, and Z direction and the front-rear direction, left-right direction, and up-down direction of the battery module 100 is not limited to the above example.

[0013] The battery module 100 will be described with reference to Fig. 1 and, if necessary, Fig. 2. The battery module 100 includes a plurality of battery cells 110 and a voltage detection device 120.

[0014] The plurality of battery cells 110 are stacked in the Y direction. Hereinafter, as necessary, the plurality of battery cells 110 stacked in the Y direction will be referred to as a stack of battery cells 110. The dimension of each battery cell 110 in the X direction is the dimension in the longitudinal direction of each battery cell 110. The dimension of each battery cell 110 in the Z direction is the dimension in the lateral direction of each battery cell 110. The dimension of each battery cell 110 in the Y direction is the dimension in the thickness direction of each battery cell 110. The shape of each battery cell 110 is not limited to this example.

[0015] Each battery cell 110 includes a battery element (not shown), an exterior material 112, a positive electrode tab 114, and a negative electrode tab 116. In one example, the battery element includes a plurality of positive electrodes and a plurality of negative electrodes (not shown) stacked alternately in the Y direction, and a separator (not shown) positioned between adjacent positive electrodes and negative electrodes in the Y direction. The exterior material 112 seals the battery element and an electrolyte (not shown). The positive electrode tab 114 is electrically connected to the positive electrode of the battery element. The positive electrode tab 114 is pulled out from one of both sides of the exterior material 112 in the X direction. The negative electrode tab 116 is electrically connected to the negative electrode of the battery element. The negative electrode tab 116 is pulled out from the other side of both sides of the exterior material 112 in the X direction. However, the structure of each battery cell 110 is not limited to this example.

[0016] Each battery cell 110 may be an all-solid-state battery. In an all-solid-state battery, a solid electrolyte layer is provided in a portion corresponding to a separator. An all-solid-state battery does not contain an electrolyte solution. Unless otherwise specified, the following description will be given assuming that each battery cell 110 is a battery cell containing an electrolyte solution.

[0017] The multiple battery cells 110 are electrically connected in a combination of series and parallel. Specifically, cell groups including at least two battery cells 110 adjacent to each other in the Y direction and connected in parallel are stacked in the Y direction and connected in series. On the −X side of the stack of battery cells 110, a positive electrode tab 114 drawn from a battery cell 110 of one cell group connected in parallel and a negative electrode tab 116 drawn from a battery cell 110 of another cell group connected in parallel are electrically connected to each other, forming a tab group 118 including the positive electrode tab 114 and the negative electrode tab 116. The positive electrode tab 114 and the negative electrode tab 116 in the tab group 118 are joined to each other by, for example, laser welding. A tab group 118 is also located on the +X side of the stack of battery cells 110. Thus, multiple cell groups are connected in series from the cell group located at one end of the stack of battery cells 110 in the Y direction to the cell group located at the other end of the stack of battery cells 110 in the Y direction. Hereinafter, as necessary, the tab group 118 located on the −X side of the stack of battery cells 110 will be referred to as the −X side tab group 118, and the tab group 118 located on the +X side of the stack of battery cells 110 will be referred to as the +X side tab group 118.

[0018] The electrical connection of the plurality of battery cells 110 is not limited to the above example. For example, a stack of battery cells 110 may be configured by connecting single battery cells 110 in series.

[0019] The voltage detection device 120 detects the voltages of the plurality of −X side tab groups 118. As shown in Figures 1 and 2, the voltage detection device 120 includes a protector 121, a plurality of voltage detection terminals 122, a plurality of flexible substrates 123, a plurality of voltage detection lines 124, a positive bus bar 125, and a negative bus bar 126.

[0020] The protector 121 covers the -X side portion of the stack of battery cells 110. The protector 121 is, for example, an insulator such as resin. The protector 121 has multiple frame bodies 121f. Each of the multiple -X side tab groups 118 is exposed toward the -X side from an opening defined by each of the multiple frame bodies 121f. Each of the multiple frame bodies 121f at least partially surrounds each of the multiple -X side tab groups 118. Therefore, each frame body 121f can protect each tab group 118 from components external to each frame body 121f.

[0021] Each of the multiple voltage detection terminals 122 is located on the -X side of each of the multiple -X side tab groups 118. Each voltage detection terminal 122 is a conductor such as metal. The +X side surface of each voltage detection terminal 122 and the -X side surface of each -X side tab group 118 are joined to each other by a joining method such as laser welding. Therefore, each voltage detection terminal 122 and each -X side tab group 118 are electrically connected to each other. Therefore, the voltage detection device 120 can detect the voltage of each -X side tab group 118 using each voltage detection terminal 122. The multiple voltage detection terminals 122 are held together by a protector 121. Therefore, by installing the protector 121 in an appropriate position relative to the stack of battery cells 110, each of the multiple voltage detection terminals 122 can be positioned appropriately relative to each of the multiple -X side tab groups 118.

[0022] The positive electrode bus bar 125 is disposed at the end portion on the -Y side of the protector 121. The positive electrode bus bar 125 is electrically connected to a positive electrode tab 114 that is drawn out to the -X side from a battery cell 110 of a cell group that is located at the end portion on the -Y side of the stack of battery cells 110. The positive electrode bus bar 125 functions as an external terminal for electrically connecting the battery module 100 to an external device such as another battery module.

[0023] The negative electrode bus bar 126 is disposed at the end portion on the +Y side of the protector 121. The negative electrode bus bar 126 is electrically connected to the negative electrode tab 116 that is drawn out to the −X side from the battery cell 110 of the cell group that is located at the end portion on the +Y side of the stack of battery cells 110. The negative electrode bus bar 126 functions as an external terminal for electrically connecting the battery module 100 to an external device such as another battery module.

[0024] 1 , the positive electrode tab 114 at the end of a group of multiple cells connected in series is drawn out toward the −X side from the battery cell 110 of the cell group located at the −Y side end of the stack of battery cells 110, and the negative electrode tab 116 at the end of a group of multiple cells connected in series is drawn out toward the −X side from the battery cell 110 of the cell group located at the +Y side end of the stack of battery cells 110. Thus, the positive electrode bus bar 125 is disposed on the −X side and the −Y side of the stack of battery cells 110, and the negative electrode bus bar 126 is disposed on the −X side and the +Y side of the stack of battery cells 110. However, the arrangement of the positive electrode tab 114 and the negative electrode tab 116 at the end of a group of multiple cells connected in series may differ depending on the number of battery cells 110 included in the stack of battery cells 110. For example, there are cases where the positive electrode tab 114 at the end of a group of multiple cells connected in series is pulled out toward the −X side from the battery cell 110 of the cell group located at the −Y side end of the stack of battery cells 110, and the negative electrode tab 116 at the end of a group of multiple cells connected in series is pulled out toward the +X side from the battery cell 110 of the cell group located at the +Y side end of the stack of battery cells 110. In this case, the positive electrode bus bar 125 is arranged on the −X side and the −Y side of the stack of battery cells 110, and the negative electrode bus bar 126 is arranged on the +X side and the +Y side of the stack of battery cells 110.

[0025] 2 and 3, the flexible substrate 123 will be described. The flexible substrate 123 includes a base film 123b and a fuse 123f.

[0026] The flexible substrate 123 is a flexible printed circuit (FPC). The flexible substrate 123 and the protector 121 are mechanically attached to each other by mechanical bonding such as engagement or clamping. When the flexible substrate 123 and the protector 121 are attached to each other, the protector 121 serves as a support body that supports the flexible substrate 123. However, the support body that supports the flexible substrate 123 may be a member different from the protector 121.

[0027] The base film 123b is disposed such that the longitudinal direction of the base film 123b is substantially parallel to the Z direction and the direction perpendicular to the base film 123b is substantially parallel to the X direction. The base film 123b has electrical insulation properties. The base film 123b is, for example, a resin film.

[0028] The fuse 123f is a conductor pattern provided on the base film 123b. In one example, the conductor pattern provided on the flexible substrate 123 may comprise only the fuse 123f. The -Z side end portion of the fuse 123f and the -Y side end portion of the voltage detection terminal 122 are electrically connected to each other. Therefore, the fuse 123f and the -X side tab group 118 are electrically connected to each other via the voltage detection terminal 122. The +Z side end portion of the fuse 123f and one end portion of the voltage detection line 124 are electrically connected to each other. The fuse 123f may be at least partially embedded in the base film 123b, or may be provided on at least one of the +X side surface and the -X side surface of the base film 123b. When a current greater than or equal to a predetermined value flows through the fuse 123f, the fuse 123f melts. The current at which the fuse 123f melts can be determined by the cross-sectional area of ​​the fuse 123f. 2, the fuse 123f is schematically illustrated as having a zigzag shape, however, the actual shape of the fuse 123f is not limited to the shape shown in FIG. 2 as long as the fuse 123f can function as a fuse.

[0029] The base film 123b is flexible. Therefore, the flexible substrate 123 is more easily deformable than a rigid substrate such as a PCB (printed circuit board). This allows for greater freedom in the shape of the fuse 123f compared to when the fuse 123f is provided on a rigid substrate. In the example shown in FIG. 2, the flexible substrate 123 can be at least partially deflected toward the +X side or the −X side. This allows the fuse 123f to more easily follow the displacement of the voltage detection terminal 122 compared to when the fuse 123f is provided on a rigid substrate.

[0030] As shown in FIG. 3, the protector 121 defines a hole 121h and a surrounding area 121s.

[0031] The hole 121h at least partially overlaps with the fuse 123f in the X direction. The surrounding region 121s at least partially surrounds the hole 121h in the X direction. The protector 121 defines a gap by the hole 121h. Therefore, the thermal conductivity of the gap inside the hole 121h is less than the thermal conductivity of the surrounding region 121s. Therefore, compared to when a region having a thermal conductivity equal to or greater than that of the surrounding region 121s is provided inside the hole 121h, it is possible to make it more difficult for heat generated from the fuse 123f to escape to the protector 121, making it easier to accurately melt the fuse 123f at the design temperature.

[0032] FIG. 4 is a diagram showing a modification of FIG.

[0033] As shown in FIG. 4 , the protector 121 may define a recess 121r instead of the hole 121h shown in FIG. 3 . The recess 121r is recessed toward the side away from the fuse 123f relative to the surrounding region 121s. Therefore, the protector 121 defines a gap by the recess 121r. Therefore, the thermal conductivity of the gap inside the recess 121r is less than the thermal conductivity of the surrounding region 121s. Therefore, compared to when a region having a thermal conductivity equal to or greater than that of the surrounding region 121s is provided inside the recess 121r, heat generated from the fuse 123f is less likely to escape to the protector 121, making it easier to accurately melt the fuse 123f at the design temperature.

[0034] The overlapping region of the protector 121 that at least partially overlaps with the fuse 123f in the X direction may include a material having a thermal conductivity lower than that of the surrounding region 121s, instead of a gap defined by a structure such as the hole 121h or the recess 121r. When the overlapping region includes such a material, heat generated from the fuse 123f is less likely to escape to the protector 121, making it easier to accurately melt the fuse 123f at the design temperature, compared to when the thermal conductivity of the overlapping region is equal to or higher than that of the surrounding region 121s.

[0035] Although the embodiments and modifications of the present invention have been described above with reference to the drawings, these are merely examples of the present invention, and various configurations other than those described above can also be adopted.

[0036] This application claims priority based on Japanese Patent Application No. 2023-106726, filed on June 29, 2023, the disclosure of which is incorporated herein by reference in its entirety.

[0037] REFERENCE SIGNS LIST 100 Battery module, 110 Battery cell, 112 Exterior material, 114 Positive electrode tab, 116 Negative electrode tab, 118 Tab group, 120 Voltage detection device, 121 Protector, 121f Frame, 121h Hole, 121r Recess, 122 Voltage detection terminal, 123 Flexible substrate, 123b Base film, 123f Fuse, 124 Voltage detection line, 125 Positive electrode bus bar, 126 Negative electrode bus bar

Claims

1. A battery module comprising: a battery cell; and a flexible substrate having a fuse electrically connected to the battery cell.

2. The battery module described in claim 1, further comprising a support to which the flexible substrate is attached, the support defining an overlapping region that at least partially overlaps the fuse and a surrounding region that at least partially surrounds the overlapping region, and the thermal conductivity of the overlapping region is less than the thermal conductivity of the surrounding region.

3. The battery module of claim 2, wherein said overlapping area defines a hole extending through said support.

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