Busbars and battery modules

Abstract

This suppresses displacement of the insulating material that at least partially surrounds the conductor acting as a fuse. [Solution] The positive busbar 30 has a narrow region 31 that acts as a fuse, having a second narrow portion 31b and a third narrow portion 31c, and a first narrow portion 31a having a cross-sectional area larger than the cross-sectional area of ​​the second narrow portion 31b and the third narrow portion 31c, and an insulating tape 34 that surrounds the first narrow portion 31a without surrounding the second narrow portion 31b and the third narrow portion 31c.

Description

Technical Field

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

Background Art

[0002] In recent years, various battery modules have been developed. A battery module includes battery cells and a bus bar electrically connected to the battery cells.

[0003] Patent Document 1 describes a bus bar assembly. The bus bar assembly includes a bus bar and a fireproof sleeve covering the fuse portion of the bus bar.

[0004] Patent Document 2 describes a bus bar plate. The bus bar plate includes a fuse portion and a heat insulating member surrounding the outer surface of the fuse portion.

[0005] Patent Document 3 describes a bus bar. The bus bar includes a curved fuse protrusion and a heat insulating member surrounding the fuse protrusion.

[0006] Patent Document 4 describes a current collector plate having a fuse portion. A notch is provided on the upper surface of the fuse portion. A groove in which an insulating layer is disposed is provided on the lower surface of the fuse portion.

[0007] Patent Document 5 describes a connecting member that electrically connects the terminals of adjacent secondary batteries to each other. The connecting member has a fuse portion that interrupts the electrical connection by the connecting member due to an overcurrent.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

[0009] A busbar may comprise a conductor that acts as a fuse and an insulating material that at least partially surrounds the conductor. In such a busbar, it may be necessary to prevent displacement of the insulating material.

[0010] One example of the object of the present invention is to suppress displacement of an insulating member that at least partially surrounds a conductor acting as a fuse. Other objects of the present invention will become apparent from the description herein. [Means for solving the problem]

[0011] One aspect of the present invention is as follows: 1. A conductor having a first portion having a first cross-sectional area and a second portion having a second cross-sectional area larger than the first cross-sectional area, and acting as a fuse, An insulating member that surrounds the first portion of the conductor but does not surround the second portion of the conductor, A bus bar equipped with a bus bar. 2. The bus bar described in 1, wherein the second part is located on both sides of the first part. 3. Battery cell and, A busbar as described in 1. or 2., electrically connected to the aforementioned battery cell, A battery module equipped with the following features. [Effects of the Invention]

[0012] According to the above aspect of the present invention, it is possible to suppress displacement of an insulating member that at least partially surrounds a conductor operating as a fuse.

Brief Description of the Drawings

[0013] [Figure 1] It is a perspective view of a battery module according to an embodiment. [Figure 2] It is a top view of a part of a positive electrode bus bar according to an embodiment. [Figure 3] It is a top view of a part of a positive electrode bus bar in a state where an insulating tape and a fixing tape are removed from FIG. 2. [Figure 4] It is a top view of a positive electrode bus bar according to a comparative example. [Figure 5] It is a temperature distribution diagram of a positive electrode bus bar according to an embodiment when an overcurrent flows through the positive electrode bus bar. [Figure 6] It is a temperature distribution diagram of a positive electrode bus bar according to a comparative example when an overcurrent flows through the positive electrode bus bar. [Figure 7] It is a top view of a positive electrode bus bar according to Modification 1. [Figure 8] It is a top view of a positive electrode bus bar according to Modification 2. [Figure 9] It is a top view of a positive electrode bus bar according to Modification 3. [Figure 10] It is a top view of a positive electrode bus bar according to Modification 4. [Figure 11] It is a top view of a positive electrode bus bar according to Modification 5. [Figure 12] It is a top view of a positive electrode bus bar according to Modification 6.

Modes for Carrying Out the Invention

[0014] Hereinafter, embodiments and modifications of the present invention will be described with reference to the drawings. In all the drawings, the same components are denoted by the same reference numerals, and the description will be omitted as appropriate.

[0015] FIG. 1 is a perspective view of a battery module 1 according to an embodiment.

[0016] Figure 1 shows arrows indicating the X, Y, and Z directions for illustrative purposes. Unless otherwise specified, the tip of the arrow indicating the X direction is considered the rear side of the battery module 1, and the base of the arrow indicating the X direction is considered the front side of the battery module 1. The Y direction is perpendicular to the X direction. The Y direction is the left-right direction of the battery module 1. Unless otherwise specified, the tip of the arrow indicating the Y direction is considered the left side of the battery module 1, and the base of the arrow indicating the Y direction is considered the right side of the battery module 1. The Z direction is perpendicular to both the X and Y directions. The Z direction is the up-down direction of the battery module 1. Unless otherwise specified, the tip of the arrow indicating the Z direction is considered the top side of the battery module 1, and the base of the arrow indicating the Z direction is considered the bottom side of the battery module 1. Hereafter, unless otherwise specified, the +X side and -X side refer to the tip and base end of the arrow indicating the X direction, respectively; the +Y side and -Y side refer to the tip and base end of the arrow indicating the Y direction, respectively; and the +Z side and -Z side refer to the tip and base end of the arrow indicating the Z direction, respectively. Note that the relationship between the X, Y, and Z directions and the front-to-back, left-to-right, and up-and-down directions of the battery module 1 is not limited to the examples given above.

[0017] Referring to Figure 1, the structure of the battery module 1 will be described.

[0018] The battery module 1 comprises a cell stack 10, a voltage detection device 20, a positive electrode busbar 30, and a negative electrode busbar 40. The cell stack 10 has a plurality of battery cells 11. The voltage detection device 20 detects the voltage of the plurality of battery cells 11. The voltage detection device 20 has a holder 21 and a plurality of voltage detection terminals 22.

[0019] Multiple battery cells 11 are stacked in the Y direction. The longitudinal direction of each battery cell 11 is approximately parallel to the X direction. The short direction of each battery cell 11 is approximately parallel to the Z direction. The thickness direction of each battery cell 11 is approximately parallel to the Y direction. The shape of each battery cell 11 is not limited to this example.

[0020] Each battery cell 11 includes a battery element (not shown), an enclosure 12, a positive electrode tab 13, and a negative electrode tab 14. In one example, the battery element includes a plurality of positive and negative electrodes (not shown) stacked alternately in the Y direction, and a separator (not shown) located between adjacent positive and negative electrodes in the Y direction. The enclosure 12 seals the battery element and an electrolyte (not shown). The positive electrode tab 13 is electrically connected to the positive electrode of the battery element. The positive electrode tab 13 is drawn out from one of the sides of the enclosure 12 in the X direction. The negative electrode tab 14 is electrically connected to the negative electrode of the battery element. The negative electrode tab 14 is drawn out from the other side of the enclosure 12 in the X direction. However, the structure of each battery cell 11 is not limited to this example.

[0021] Each battery cell 11 may be an all-solid-state battery. In an all-solid-state battery, a solid electrolyte layer is provided in the portion corresponding to the separator. All-solid-state batteries do not contain electrolyte. Hereafter, unless otherwise specified, each battery cell 11 will be described as a battery cell containing electrolyte.

[0022] In this embodiment, multiple battery cells 11 are electrically connected by a combination of series and parallel connections. Specifically, a group of cells, each containing at least two adjacent battery cells 11 connected in parallel in the Y direction, is stacked in the Y direction and connected in series. On the -X side of the cell stack 10, a positive electrode tab 13 drawn from a battery cell 11 of a parallel-connected cell group and a negative electrode tab 14 drawn from a battery cell 11 of another parallel-connected cell group are electrically connected to each other to form a tab connection portion 15 including the positive electrode tab 13 and the negative electrode tab 14. The positive electrode tab 13 and the negative electrode tab 14 in the tab connection portion 15 are joined to each other, for example, by laser welding. A group of tabs is similarly formed on the +X side of the cell stack 10. Thus, multiple groups of cells are connected in series from the aforementioned cell group located on one end of the cell stack 10 in the Y direction to the aforementioned cell group located on the other end of the cell stack 10 in the Y direction.

[0023] The electrical connections of the multiple battery cells 11 are not limited to the examples described above. For example, a single battery cell 11 may be connected in series to form a cell stack 10.

[0024] The holder 21 is positioned on the -X side relative to the cell stack 10. The holder 21 defines a plurality of openings 211. Each of the plurality of tab connection portions 15 is exposed toward the -X side through each of the plurality of openings 211. The holder 21 integrally holds a plurality of voltage detection terminals 22. Therefore, by installing the holder 21 at an appropriate position relative to the cell stack 10, each of the plurality of voltage detection terminals 22 can be positioned at an appropriate position relative to each of the plurality of tab connection portions 15.

[0025] The +X side of each voltage detection terminal 22 and the -X side of each tab connection part 15 are joined to each other by a joining method such as laser welding. Therefore, each voltage detection terminal 22 and each tab connection part 15 are electrically connected to each other. Consequently, the voltage detection device 20 can detect the voltage of each tab connection part 15 using each voltage detection terminal 22. Each voltage detection terminal 22 is electrically connected to a connector (not shown) via a voltage detection line such as a harness (not shown).

[0026] The positive electrode busbar 30 is located at the -Y end of the holder 21. The positive electrode busbar 30 and the positive electrode tab 13 drawn from the group of cells located at the -Y end of the cell stack 10 are electrically connected to each other. The positive electrode busbar 30 functions as an external terminal for electrically connecting to external devices such as other battery modules. The negative electrode busbar 40 is located at the +Y end of the holder 21. The negative electrode busbar 40 and the negative electrode tab 14 drawn from the group of cells located at the +Y end of the cell stack 10 are electrically connected to each other. The negative electrode busbar 40 functions as an external terminal for electrically connecting to external devices such as other battery modules.

[0027] A voltage detection device similar to the voltage detection device 20 is provided on the +X side of the cell stack 10, except that a positive electrode busbar 30 and a negative electrode busbar 40 are not provided. Therefore, the voltage of multiple tab connections on the +X side of the cell stack 10 can be detected.

[0028] In this embodiment, the positive electrode tab 13 at the end of a series-connected group of cells is a positive electrode tab 13 drawn out toward the -X side from the battery cell 11 of the cell group located at the -Y end of the cell stack 10, and the negative electrode tab 14 at the end of a series-connected group of cells is a negative electrode tab 14 drawn out toward the -X side from the battery cell 11 of the cell group located at the +Y end of the cell stack 10. Therefore, both the positive electrode busbar 30 and the negative electrode busbar 40 are located on the -X side of the battery cell 11. However, the arrangement of the positive electrode tab 13 and the negative electrode tab 14 at the end of a series-connected group of cells may differ depending on the number of battery cells 11 included in the cell stack 10. In one example, the positive electrode tab 13 at the end of a group of cells connected in series may be a positive electrode tab 13 drawn out toward the +X side from a battery cell 11 of a group of cells located at the -Y end of the cell stack 10, and the negative electrode tab 14 at the end of a group of cells connected in series may be a negative electrode tab 14 drawn out toward the -X side from a battery cell 11 of a group of cells located at the +Y end of the cell stack 10. In this example, the positive electrode busbar 30 is located on the +X side of the cell stack 10, and the negative electrode busbar 40 is located on the -X side of the cell stack 10.

[0029] Figure 2 is a top view of a portion of the positive electrode busbar 30 according to the embodiment. Figure 3 is a top view of a portion of the positive electrode busbar 30 in which the insulating tape 34 and fixing tape 35 have been removed from Figure 2. In Figures 2 and 3, the white circle with a black dot indicating the Z direction indicates that the tip of the arrow indicating the Z direction is pointed towards the front of the paper. The portion of the positive electrode busbar 30 shown in Figures 2 and 3 is located on the +Z side with respect to the tab connection portion 15 located on the -Y side among the multiple tab connection portions 15 on the -X side of the cell laminate 10 in Figure 1.

[0030] The positive busbar 30 will be described with reference to Figures 2 and 3. The matters described for the positive busbar 30 with reference to Figures 2 and 3 are also applicable to the negative busbar 40.

[0031] The positive electrode busbar 30 is a conductor. The positive electrode busbar 30 is made of a metal such as copper. In the example shown in Figures 2 and 3, the positive electrode busbar 30 has a substantially plate shape and is positioned substantially perpendicular to the Z direction. As shown in Figures 2 and 3, the positive electrode busbar 30 has a narrow region 31, a first wide region 32, and a second wide region 33. In one example, the narrow region 31 is formed by punching out a portion of the metal that makes up the positive electrode busbar 30.

[0032] The narrow region 31 is configured to act as a fuse. When an overcurrent exceeding a certain value flows through the narrow region 31, the narrow region 31 melts. For example, when an overcurrent of 6000A or more flows through the narrow region 31, the narrow region 31 melts.

[0033] As shown in Figure 3, the narrow region 31 includes a first straight edge 311, a second straight edge 312, a first protruding edge 313, and a second protruding edge 314. As shown in Figure 3, viewed from the Z direction, the first straight edge 311 is the +X side edge of the narrow region 31 and extends in the Y direction. As shown in Figure 3, viewed from the Z direction, the second straight edge 312 is the -X side edge of the narrow region 31 and extends in the Y direction. As shown in Figure 3, the first protruding edge 313 is located on the +Y side relative to the second straight edge 312 and is located on the -X side of the second straight edge 312. As shown in Figure 3, the second protruding edge 314 is located on the -Y side relative to the second straight edge 312 and is located on the -X side of the second straight edge 312.

[0034] Unless otherwise specified, the first narrow portion 31a refers to the portion of the narrow region 31 between the first straight edge 311 and the second straight edge 312 in the X direction. Unless otherwise specified, the second narrow portion 31b refers to the portion of the narrow region 31 between the first straight edge 311 and the first protruding edge 313 in the X direction. In the example shown in Figure 3, the second narrow portion 31b is located at the +Y end of the narrow region 31. Unless otherwise specified, the third narrow portion 31c refers to the portion of the narrow region 31 between the first straight edge 311 and the second protruding edge 314 in the X direction. In the example shown in Figure 3, the third narrow portion 31c is located at the -Y end of the narrow region 31.

[0035] Figure 3 shows, for illustrative purposes, a first plane 31d and a second plane 31e virtually. The first plane 31d crosses the +Y side end of the narrow region 31 perpendicular to the X direction, and the second plane 31e crosses the -Y side end of the narrow region 31 perpendicular to the X direction. In Figure 3, the X direction is the direction connecting the +Y side end and the -Y side end of the narrow region 31.

[0036] As shown in Figure 3, the width of the first narrow portion 31a in the X direction is approximately constant regardless of its position within the narrow region 31 in the X direction. As shown in Figure 3, the width of the second narrow portion 31b in the X direction is wider than the width of the first narrow portion 31a in the X direction by the distance that the first protruding edge 313 protrudes -X from the second straight edge 312. As shown in Figure 3, the width of the third narrow portion 31c in the X direction is wider than the width of the first narrow portion 31a in the X direction by the distance that the second protruding edge 314 protrudes -X from the second straight edge 312. In the example shown in Figure 3, the width of the second narrow portion 31b in the X direction and the width of the third narrow portion 31c in the X direction are approximately equal. The widths of the second narrow portion 31b in the X direction and the width of the third narrow portion 31c in the X direction may be different from each other.

[0037] As shown in Figure 3, the narrow region 31 defines a first notch 315 located between the second straight edge 312 and the first protruding edge 313, and a second notch 316 located between the second straight edge 312 and the second protruding edge 314. As shown in Figure 3, when viewed from the Z direction, the first notch 315 and the second notch 316 are rounded in a convex shape towards the +X side. As shown in Figure 3, when viewed from the Z direction, the first notch 315 and the second notch 316 are located at approximately equal distances apart from each other in the Y direction from the approximate center of the narrow region 31 in the Y direction. The shape and position of the first notch 315 and the second notch 316 are not limited to the example shown in Figure 3. The number of notches provided in the narrow region 31 does not have to be two, such as the first notch 315 and the second notch 316; there may be only one, or there may be three or more.

[0038] As shown in Figure 3, the first wide region 32 is located on the +Y side relative to the narrow region 31. The +Y end of the narrow region 31 and the -Y end of the first wide region 32 are electrically connected to each other. The first wide region 32 is configured to remain unblended even if the narrow region 31 acts as a fuse and melts.

[0039] As shown in Figure 3, the first wide region 32 includes a first edge 321 and a second edge 322. As shown in Figure 3, viewed from the Z direction, the first edge 321 is the +X side edge of the first wide region 32. As shown in Figure 3, viewed from the Z direction, the first straight edge 311 and the first edge 321 are located on the same straight line extending in the Y direction. As shown in Figure 3, viewed from the Z direction, the second edge 322 is the -X side edge of the first wide region 32. As shown in Figure 3, viewed from the Z direction, the second edge 322 is located -X side of the first protruding edge 313. As shown in Figure 3, the width in the X direction between the first edge 321 and the second edge 322 of the first wide region 32 is wider than the width in the X direction of the second narrow portion 31b by the distance that the second edge 322 protrudes -X side from the first protruding edge 313.

[0040] As shown in Figure 3, the first wide region 32 includes a first oblique edge 323 that intersects the first protruding edge 313. As shown in Figure 3, viewed from the Z direction, the first oblique edge 323 is inclined obliquely to the +Y side as it moves away from the first protruding edge 313. Therefore, as shown in Figure 3, viewed from the Z direction, the first oblique edge 323 extends to the +Y side away from the second plane 31e as it moves away from the first protruding edge 313. When an overcurrent flows through the narrow region 31 and the narrow region 31 is melted, the -Y side end of the narrow region 31 may remain. In this embodiment, compared to the case where the first oblique edge 323 is arranged parallel to the X direction, it is possible to secure a distance between the distal portion of the second narrow portion 31b of the first oblique edge 323 and the -Y side end of the narrow region 31 after the narrow region 31 has been melted. Therefore, after cutting the narrow region 31, arc discharge can be suppressed between the distal portion of the second narrow portion 31b of the first oblique edge 323 and the -Y side end of the narrow region 31.

[0041] As shown in Figure 3, when viewed from the Z direction, the corner between the +Y end of the first protruding edge 313 and the +X end of the first oblique edge 323 is rounded. Therefore, compared to the case where the corner between the +Y end of the first protruding edge 313 and the +X end of the first oblique edge 323 is angular, it is possible to more easily distribute the stress around the corner between the +Y end of the first protruding edge 313 and the +X end of the first oblique edge 323.

[0042] As shown in Figure 3, when viewed from the Z direction, the corner between the -Y end of the second edge 322 and the -X end of the first oblique edge 323 is rounded. Therefore, compared to the case where the corner between the -Y end of the second edge 322 and the -X end of the first oblique edge 323 is angular, it is possible to more easily distribute the stress around the corner between the -Y end of the second edge 322 and the -X end of the first oblique edge 323.

[0043] As shown in Figure 3, the second wide region 33 is located on the -Y side relative to the narrow region 31. The -Y side end of the narrow region 31 and the +Y side end of the second wide region 33 are electrically connected to each other. The second wide region 33 is configured to remain unfrozen even if the narrow region 31 acts as a fuse and melts.

[0044] As shown in Figure 3, the second wide region 33 includes the third edge 331 and the fourth edge 332. As shown in Figure 3, viewed from the Z direction, the third edge 331 is the +X side edge of the second wide region 33. As shown in Figure 3, viewed from the Z direction, the first straight edge 311 and the third edge 331 are located on the same straight line extending in the Y direction. As shown in Figure 3, viewed from the Z direction, the fourth edge 332 is the -X side edge of the second wide region 33. As shown in Figure 3, viewed from the Z direction, the fourth edge 332 is located -X side of the second protruding edge 314. As shown in Figure 3, the width in the X direction between the third edge 331 and the fourth edge 332 of the second wide region 33 is wider than the width in the X direction of the third narrow portion 31c by the distance that the fourth edge 332 protrudes -X side from the second protruding edge 314.

[0045] As shown in Figure 3, the second wide region 33 includes a second oblique edge 333 that intersects the second protruding edge 314. As shown in Figure 3, viewed from the Z direction, the second oblique edge 333 is inclined obliquely to the -Y side as it moves away from the second protruding edge 314. Therefore, as shown in Figure 3, viewed from the Z direction, the second oblique edge 333 extends to the -Y side away from the first plane 31d as it moves away from the second protruding edge 314. When an overcurrent flows through the narrow region 31 and the narrow region 31 is melted, the +Y side end of the narrow region 31 may remain. In this embodiment, compared to the case where the second oblique edge 333 is arranged parallel to the X direction, it is possible to secure a distance between the distal portion of the third narrow portion 31c of the second oblique edge 333 and the +Y side end of the narrow region 31 after the narrow region 31 has been melted. Therefore, after cutting the narrow region 31, the arc discharge between the distal portion of the third narrow portion 31c of the second oblique edge 333 and the +Y side end of the narrow region 31 can be suppressed.

[0046] As shown in Figure 3, when viewed from the Z direction, the corner between the -Y end of the second protruding edge 314 and the +X end of the second oblique edge 333 is rounded. Therefore, compared to the case where the corner between the -Y end of the second protruding edge 314 and the +X end of the second oblique edge 333 is angular, it is possible to more easily distribute the stress around the corner between the -Y end of the second protruding edge 314 and the +X end of the second oblique edge 333.

[0047] As shown in Figure 3, when viewed from the Z direction, the corner between the +Y end of the fourth edge 332 and the -X end of the second oblique edge 333 is rounded. Therefore, compared to the case where the corner between the +Y end of the fourth edge 332 and the -X end of the second oblique edge 333 is angular, it is possible to more easily distribute the stress around the corner between the +Y end of the fourth edge 332 and the -X end of the second oblique edge 333.

[0048] As shown in Figure 2, the positive busbar 30 further includes an insulating tape 34 and a fixing tape 35. Hereafter, unless otherwise specified, the axial direction of the narrow region 31 refers to the direction passing through the center of the cross-section perpendicular to the Y direction of the narrow region 31 in the Y direction.

[0049] The insulating tape 34 is wound around the axial direction of the first narrow portion 31a. Therefore, the insulating tape 34 acts as an insulating member that surrounds the first narrow portion 31a around the axial direction of the narrow region 31. When the first narrow portion 31a acts as a fuse and melts, an arc discharge may occur between the two ends of the first narrow portion 31a in the Y direction. By surrounding the first narrow portion 31a around the axial direction with the insulating tape 34, the arc discharge can be contained within the region surrounded by the insulating tape 34.

[0050] The insulating tape 34 has heat resistance that can withstand the heat generated during the normal operation of the positive electrode busbar 30. The insulating tape 34 does not need to withstand the heat generated when the first narrow portion 31a is cut. For example, the insulating tape 34 does not need to withstand temperatures above the melting point of copper, which is 1085°C, that constitutes the first narrow portion 31a. However, the insulating tape 34 may have fire resistance. If the insulating tape 34 has fire resistance, the fire resistance of the first narrow portion 31a can be improved. The insulating tape 34 contains, for example, glass fiber, ceramic, or Si compound.

[0051] As can be seen from Figures 2 and 3, the insulating tape 34 exposes the second narrow portion 31b and the third narrow portion 31c, surrounding the first narrow portion 31a around the axial direction of the narrow region 31. As shown in Figure 3, the first protruding edge 313 and the second protruding edge 314 are located on the -X side of the second straight edge 312. Therefore, displacement of the insulating tape 34 towards the +Y side can be suppressed by the contact between the +Y side end of the insulating tape 34 and the first protruding edge 313. Furthermore, displacement of the insulating tape 34 towards the -Y side can be suppressed by the contact between the -Y side end of the insulating tape 34 and the second protruding edge 314. In addition, compared to the case where the insulating tape 34 surrounds the second narrow portion 31b and the third narrow portion 31c around the axial direction of the narrow region 31, when the first narrow portion 31a is cut, ambient low-temperature air can more easily flow into the space between the second narrow portion 31b and the third narrow portion 31c. Therefore, the dielectric strength of the space can be restored, and the resistance of the arc discharge between the two ends of the narrow region 31 in the Y direction can be increased.

[0052] The structure for suppressing the Y-direction displacement of the insulating tape 34 is not limited to the examples described above. For example, one of the first protruding edge 313 and the second protruding edge 314 may be omitted. For example, if the second protruding edge 314 is not provided and the first protruding edge 313 is provided, the displacement of the insulating tape 34 toward the +Y side can be suppressed by the contact between the +Y side end of the insulating tape 34 and the first protruding edge 313. If the first protruding edge 313 is not provided and the second protruding edge 314 is provided, the displacement of the insulating tape 34 toward the -Y side can be suppressed by the contact between the -Y side end of the insulating tape 34 and the second protruding edge 314.

[0053] As can be seen from the above explanation, in order to suppress the positional displacement of the insulating tape 34 in the Y direction, it is necessary that the cross-sectional area perpendicular to the Y direction of the portion of the insulating tape 34 located on at least one side of the Y-direction of the insulating tape 34 in the narrow region 31 is larger than the cross-sectional area perpendicular to the Y direction of the portion enclosed by the insulating tape 34 in the narrow region 31. In this embodiment, the width in the X direction of the second narrow portion 31b and the third narrow portion 31c is wider than the width in the X direction of the first narrow portion 31a, so the cross-sectional area perpendicular to the Y direction of the second narrow portion 31b and the third narrow portion 31c is larger than the cross-sectional area perpendicular to the Y direction of the first narrow portion 31a. To make the cross-sectional area perpendicular to the Y direction of the portions of the insulating tape 34 located on both sides in the Y direction of the narrow region 31 larger than the cross-sectional area perpendicular to the Y direction of the portion enclosed by the insulating tape 34 of the narrow region 31, for example, the thickness in the Z direction of the portions of the insulating tape 34 located on both sides in the Y direction of the narrow region 31 may be made thicker than the thickness in the Z direction of the portion enclosed by the insulating tape 34 of the narrow region 31.

[0054] In this embodiment, the first notch 315 and the second notch 316 can be used as markers for the position where the insulating tape 34 is to be placed. In the example shown in Figure 2, the insulating tape 34 is placed such that the +Y side end of the insulating tape 34 overlaps with the approximate center portion in the Y direction of the first notch 315, and the -Y side end of the insulating tape 34 overlaps with the approximate center portion in the Y direction of the second notch 316. Therefore, the insulating tape 34 can be positioned by the positional relationship between the +Y side end of the insulating tape 34 and the approximate center portion in the Y direction of the first notch 315, and the positional relationship between the -Y side end of the insulating tape 34 and the approximate center portion in the Y direction of the second notch 316. The +Y side end of the insulating tape 34 may overlap with the +Y side or -Y side end of the first notch 315 instead of the approximate center portion in the Y direction of the first notch 315. The -Y side end of the insulating tape 34 may be superimposed on the +Y side or -Y side end of the second notch 316, instead of the approximately central portion of the second notch 316 in the Y direction.

[0055] The fixing tape 35 is wound around the insulating tape 34 around the axial direction of the narrow region 31. In the example shown in Figure 2, the length of the fixing tape 35 in the Y direction is less than the length of the insulating tape 34 in the Y direction. In the example shown in Figure 2, both ends of the insulating tape 34 in the Y direction are not covered by the fixing tape 35 and are exposed from the fixing tape 35. By winding the fixing tape 35 around the insulating tape 34, the insulating tape 34 can be fixed more firmly. The positive electrode busbar 30 does not necessarily have to have the fixing tape 35. For example, if the insulating tape 34 can be sufficiently adhered to the first narrow portion 31a without the fixing tape 35, the fixing tape 35 can be made unnecessary.

[0056] Figure 4 is a top view of the positive electrode busbar 30 according to a comparative example. The positive electrode busbar 30 according to the comparative example is the same as the positive electrode busbar 30 according to the embodiment, except for the following points.

[0057] As shown in Figure 4, in the comparative example of the positive electrode busbar 30, the width of the narrow region 31 in the X direction is constant regardless of its position within the Y direction of the narrow region 31. As shown in Figure 4, in the comparative example of the positive electrode busbar 30, the second straight edge 312 on the -X side of the narrow region 31 does not define a notch corresponding to the first notch 315 and the second notch 316 according to the embodiment. As shown in Figure 4, in the comparative example of the positive electrode busbar 30, when viewed from the Z direction, the edge of the first wide region 32 between the +Y side end of the second straight edge 312 and the -Y side end of the second edge 322 is substantially parallel to the X direction. As shown in Figure 4, in the comparative example of the positive electrode busbar 30, when viewed from the Z direction, the edge of the second wide region 33 between the -Y side end of the second straight edge 312 and the +Y side end of the fourth edge 332 is substantially parallel to the X direction.

[0058] Figure 5 is a temperature distribution diagram of the positive electrode busbar 30 according to the embodiment when an overcurrent flows through the positive electrode busbar 30. Figure 6 is a temperature distribution diagram of the positive electrode busbar 30 according to a comparative example when an overcurrent flows through the positive electrode busbar 30.

[0059] In the comparative example shown in Figure 6, in the initial stages of the narrow region 31 melting, the temperature of the entire narrow region 31 does not rise uniformly; rather, the temperature of the approximately central part of the narrow region 31 in the Y direction tends to rise more easily than the temperatures of the ends of the narrow region 31 in the Y direction. Therefore, in the comparative example, in the initial stages of the narrow region 31 melting, only the approximately central part of the narrow region 31 in the Y direction tends to melt. When only the approximately central part of the narrow region 31 in the Y direction melts, arc discharge tends to continue through the space formed by the melting of the approximately central part of the narrow region 31 in the Y direction. If a relatively high voltage is applied to the positive busbar 30 while this arc discharge continues, it may become difficult to ensure electrical insulation through the space formed by the melting of the approximately central part of the narrow region 31 in the Y direction. If this electrical insulation is not ensured, it may become difficult to make the narrow region 31 function adequately as a fuse.

[0060] As shown in Figure 5, in this embodiment, the temperature of the first narrow portion 31a is substantially uniform between the first notch 315 and the second notch 316. Therefore, in this embodiment, compared to the comparative example, the range in the Y direction over which the narrow region 31 is melted can be widened in the initial stages of melting of the narrow region 31. Thus, in this embodiment, the narrow region 31 can be made to operate more reliably as a fuse compared to the comparative example. The reason why the temperature of the first narrow portion 31a is substantially uniform between the first notch 315 and the second notch 316 in this embodiment is presumed to be as follows.

[0061] In this embodiment, the cross-sectional area perpendicular to the Y direction of the portion of the narrow region 31 where the first notch 315 is provided and the cross-sectional area perpendicular to the Y direction of the portion of the narrow region 31 where the second notch 316 is provided are the smallest within the entire Y-direction of the narrow region 31. Therefore, during the initial cutting of the narrow region 31, the temperature of the narrow region 31 is highest around the first notch 315 and the second notch 316. Heat from the second narrow portion 31b is easily conducted to the first wide region 32. Therefore, the temperature of the second narrow portion 31b does not rise as easily as the temperature of the first narrow portion 31a. Heat from the third narrow portion 31c is easily conducted to the second wide region 33. Therefore, the temperature of the third narrow portion 31c does not rise as easily as the temperature of the first narrow portion 31a. The heat in the first narrow section 31a is less easily dissipated than the heat in the second narrow section 31b and the third narrow section 31c. Therefore, the temperature of the first narrow section 31a rises more easily than the temperature of the second narrow section 31b and the third narrow section 31c. Thus, the temperature of the first narrow section 31a tends to rise uniformly over almost the entire Y-direction of the first narrow section 31a.

[0062] As can be seen from the above explanation, the first notch 315 and the second notch 316 are structured to preferentially raise the temperature of the area surrounding the first notch 315 and the second notch 316 of the narrow region 31 compared to the temperature of other parts of the narrow region 31 when an overcurrent flows through the narrow region 31. In this embodiment, by providing the first notch 315 and the second notch 316 on both sides in the Y direction relative to the approximate center of the narrow region 31 in the Y direction, the temperature of the area located between the first notch 315 and the second notch 316 of the narrow region 31 is raised substantially uniformly. Therefore, depending on the position of the notches such as the first notch 315 and the second notch 316, the cutting range of the narrow region 31 can be widened in the Y direction at a desired position in the narrow region 31.

[0063] The structure that preferentially raises the temperature of one part of the narrow region 31 over the temperature of other parts of the narrow region 31 is not limited to structures such as the first notch 315 and the second notch 316, which make the width of one part of the narrow region 31 in the X direction narrower than the width of other parts of the narrow region 31 in the X direction. The structure that preferentially raises the temperature of one part of the narrow region 31 over the temperature of other parts of the narrow region 31 may also be a structure in which the cross-sectional area perpendicular to the Y direction of one part of the narrow region 31 is smaller than the cross-sectional area perpendicular to the Y direction of other parts of the narrow region 31. For example, the thickness in the Z direction of one part of the narrow region 31 may be thinner than the thickness in the Z direction of other parts of the narrow region 31.

[0064] The structure that preferentially raises the temperature of one part of the narrow region 31 over the temperature of other parts of the narrow region 31 is not limited to structures such as the first notch 315 and the second notch 316, which make the cross-sectional area of ​​one part of the narrow region 31 perpendicular to the Y direction smaller than the cross-sectional area of ​​other parts of the narrow region 31 perpendicular to the Y direction. For example, the insulating tape 34 may be a heat conductive member. When the insulating tape 34 is a heat conductive member, the insulating tape 34 has a structure that preferentially raises the temperature of the part of the narrow region 31 surrounded by the insulating tape 34 around the axial direction of the narrow region 31 over the temperature of the part of the narrow region 31 not surrounded by the insulating tape 34 around the axial direction of the narrow region 31. Furthermore, the thermal conductivity of the insulating tape 34 makes it easier to raise the temperature of the part of the narrow region 31 surrounded by the insulating tape 34 substantially uniformly. For example, as shown in Figures 2 and 3, the insulating tape 34 may surround the first narrow portion 31a but not the second narrow portion 31b and the third narrow portion 31c. In the example shown in Figures 2 and 3, if the insulating tape 34 is a heat conductive member, the thermal conductivity of the insulating tape 34 can preferentially raise the temperature of the first narrow portion 31a above that of the second narrow portion 31b and the third narrow portion 31c. Therefore, depending on the position of the insulating tape 34, the melting range of the narrow region 31 can be widened in the Y direction at a desired position in the narrow region 31.

[0065] In one example, the insulating tape 34 as a heat conductive member described above may contain an electrically insulating material having a higher thermal conductivity than the material constituting the narrow region 31. By having an insulating tape 34 with a higher thermal conductivity than the material constituting the narrow region 31, the temperature of the first narrow portion 31a can be raised preferentially over the temperatures of the second narrow portion 31b and the third narrow portion 31c. Furthermore, because the insulating tape 34 is electrically insulating, arc discharge through the insulating tape 34 can be suppressed after the narrow region 31 is cut, compared to the case where the insulating tape 34 is conductive. Examples of materials contained in the insulating tape 34 as a heat conductive member described above include a combination of silicone and ceramic filler, or a combination of epoxy and filler.

[0066] Figure 7 is a top view of the positive electrode busbar 30 according to Modification 1. The positive electrode busbar 30 according to Modification 1 is the same as the positive electrode busbar 30 according to the embodiment, except for the following points.

[0067] As shown in Figure 7, when viewed from the Z direction, the first protruding edge 313 and the second protruding edge 314 may be located on the +X side of the narrow region 31. In the example shown in Figure 7, when viewed from the Z direction, the first protruding edge 313 and the second protruding edge 314 are located on the +Y side and -Y side, respectively, with respect to the first straight edge 311 on the +X side of the narrow region 31, and are located on the +X side of the first straight edge 311 on the +X side of the narrow region 31. In the example shown in Figure 7, when viewed from the Z direction, the first protruding edge 313 and the first edge 321 are located on the same straight line extending in the Y direction. In the example shown in Figure 7, when viewed from the Z direction, the second protruding edge 314 and the third edge 331 are located on the same straight line extending in the Y direction. In the example shown in Figure 7, the second straight edge 312 on the -X side of the narrow region 31 extends in the Y direction between the -X end and the +X end of the narrow region 31.

[0068] In the modified example 1 as well, when an overcurrent flows through the narrow region 31, the temperature of the portion of the narrow region 31 between the first notch 315 and the second notch 316 can be made to rise uniformly. Therefore, the cutting range of the narrow region 31 can be widened in the Y direction at a desired position in the narrow region 31.

[0069] In Modification 1, as in the embodiment, the insulating tape 34 may at least partially surround the first narrow portion 31a around the axial direction of the narrow region 31. In Modification 1, the displacement of the insulating tape 34 toward the +Y side can be suppressed by the contact between the +Y side end of the insulating tape 34 and the first protruding edge 313. Furthermore, the displacement of the insulating tape 34 toward the -Y side can be suppressed by the contact between the -Y side end of the insulating tape 34 and the second protruding edge 314.

[0070] Figure 8 is a top view of the positive electrode busbar 30 according to Modification 2. The positive electrode busbar 30 according to Modification 2 is the same as the positive electrode busbar 30 according to the embodiment, except for the following points.

[0071] As shown in Figure 8, the first notch 315 and the second notch 316 may be provided on the opposite edge of the narrow region 31 in the X direction when viewed from the Z direction. In the example shown in Figure 8, the first notch 315 is provided in the portion of the first straight edge 311 between the first narrow portion 31a and the second narrow portion 31b. In the example shown in Figure 8, the second notch 316 is provided between the second straight edge 312 and the second protruding edge 314.

[0072] In the modified example 2, when an overcurrent flows through the narrow region 31, the temperature of the portion of the narrow region 31 between the first notch 315 and the second notch 316 can be made to rise more uniformly. Therefore, the cutting range of the narrow region 31 can be widened in the Y direction at a desired position in the narrow region 31.

[0073] In Modification 2, as in the embodiment, the insulating tape 34 may at least partially surround the first narrow portion 31a around the axial direction of the narrow region 31. In Modification 2, the displacement of the insulating tape 34 toward the +Y side can be suppressed by the contact between the +Y side end of the insulating tape 34 and the first protruding edge 313. Furthermore, the displacement of the insulating tape 34 toward the -Y side can be suppressed by the contact between the -Y side end of the insulating tape 34 and the second protruding edge 314.

[0074] Figure 9 is a top view of the positive electrode busbar 30 according to Modification 3. The positive electrode busbar 30 according to Modification 3 is the same as the positive electrode busbar 30 according to the embodiment, except for the following points.

[0075] As shown in Figure 9, the narrow region 31 does not necessarily include protruding edges corresponding to the first protruding edge 313 and the second protruding edge 314 according to the embodiment. In the example shown in Figure 9, a first notch 315 is provided at the corner between the +Y side end of the second straight edge 312 and the +X side end of the first diagonal edge 323. In the example shown in Figure 9, a second notch 316 is provided at the corner between the -Y side end of the second straight edge 312 and the +X side end of the second diagonal edge 333.

[0076] In the modified example 2, when an overcurrent flows through the narrow region 31, the temperature of the portion of the narrow region 31 between the first notch 315 and the second notch 316 can be made to rise more uniformly. Therefore, the cutting range of the narrow region 31 can be widened in the Y direction at a desired position in the narrow region 31.

[0077] Figure 10 is a top view of the positive electrode busbar 30 according to Modification 4. The positive electrode busbar 30 according to Modification 4 is the same as the positive electrode busbar 30 according to the embodiment, except for the following points.

[0078] As shown in Figure 10, the narrow region 31 does not have to have a protruding edge corresponding to the first protruding edge 313 in the embodiment, nor does it have to define a notch corresponding to the first notch 315 in the embodiment. In the example shown in Figure 10, similar to the embodiment, the narrow region 31 includes a second protruding edge 314 and defines a second notch 316.

[0079] In the modified example 4, when an overcurrent flows through the narrow region 31, the temperature around the second notch 316 of the narrow region 31 can be easily increased. Therefore, compared to the case where neither the first notch 315 nor the second notch 316 is defined in the narrow region 31, the temperature of the narrow region 31 can be increased more uniformly from the approximate center of the narrow region 31 in the Y direction to the second notch 316. Consequently, the cutting position of the narrow region 31 can be controlled to the portion between the approximate center of the narrow region 31 in the Y direction and the second notch 316. Therefore, compared to the case where the second notch 316 is not provided, the cutting range of the narrow region 31 can be widened in the Y direction at a desired position in the narrow region 31.

[0080] In Modification 4, as in the embodiment, the insulating tape 34 may at least partially surround the first narrow portion 31a around the axial direction of the narrow region 31. In Modification 4, as well, displacement of the insulating tape 34 toward the -Y side can be suppressed by contact between the -Y side end of the insulating tape 34 and the second protruding edge 314.

[0081] Figure 11 is a top view of the positive electrode busbar 30 according to Modification 5. The positive electrode busbar 30 according to Modification 5 is the same as the positive electrode busbar 30 according to the embodiment, except for the following points.

[0082] In the example shown in Figure 11, a first notch 315 is provided in the +Y side portion of the first straight edge 311 of the narrow region 31. As shown in Figure 11, the width of the narrow region 31 in the X direction may be substantially constant regardless of its position in the Y direction of the narrow region 31, except for the portion of the narrow region 31 where the first notch 315 is provided in the +Y side portion.

[0083] In Modification 5, when an overcurrent flows through the narrow region 31, the temperature around the first notch 315 of the narrow region 31 can be easily increased. Therefore, compared to the case where neither the first notch 315 nor the second notch 316 is defined in the narrow region 31, the temperature of the narrow region 31 can be increased more uniformly from the approximately central part of the narrow region 31 in the Y direction to the first notch 315. Thus, the cutting position of the narrow region 31 can be controlled to the part between the approximately central part of the narrow region 31 in the Y direction and the first notch 315. Therefore, compared to the case where the first notch 315 is not provided, the cutting range of the narrow region 31 can be widened in the Y direction at a desired position in the narrow region 31.

[0084] In the example shown in Figure 11, a first notch 315 is provided on the +Y side of the first straight edge 311 of the narrow region 31. In other examples, the first notch 315 may not be provided, and a second notch 316 may be provided on the -Y side of the first straight edge 311 of the narrow region 31. In these other examples, the cutting position of the narrow region 31 can be controlled to the portion between the approximately central part of the narrow region 31 in the Y direction and the first notch 315.

[0085] Figure 12 is a top view of the positive electrode busbar 30 according to Modification 6. The positive electrode busbar 30 according to Modification 6 is the same as the positive electrode busbar 30 according to the embodiment, except for the following points.

[0086] In the example shown in Figure 12, a first notch 315 is provided in the approximate center of the second straight edge 312 of the narrow region 31 in the Y direction. As shown in Figure 12, the width of the narrow region 31 in the X direction may be approximately constant regardless of its position within the narrow region 31 in the Y direction, except for the portion where the first notch 315 is provided in the approximate center of the narrow region 31 in the Y direction.

[0087] In modification 6, when an overcurrent flows through the narrow region 31, the temperature around the first notch 315 of the narrow region 31 can be easily increased. Therefore, compared to the case where the narrow region 31 does not define the first notch 315, the fusion range of the narrow region 31 can be made narrower in the Y direction. Consequently, the narrow region 31 can be fused in a shorter time. For example, if the voltage applied to the narrow region 31 is low, even if the fusion range of the narrow region 31 in the Y direction is narrowed, the narrow region 31 can still function as a fuse. Therefore, depending on the position of the notch, such as the first notch 315, the fusion range of the narrow region 31 can be narrowed in the Y direction as well as widened.

[0088] 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]

[0089] 1 Battery module, 10 Cell stack, 11 Battery cell, 12 Outer material, 13 Positive electrode tab, 14 Negative electrode tab, 15 Tab connection part, 20 Voltage detection device, 21 Holder, 211 Opening, 22 Voltage detection terminal, 30 Positive electrode busbar, 31 Narrow region, 31a First narrow portion, 31b Second narrow portion, 31c Third narrow portion, 31d First plane, 31e Second plane, 311 First straight edge, 312 Second straight edge, 313 First protruding edge, 314 Second protruding edge, 315 First notch, 316 Second notch, 32 First wide region, 321 First edge, 322 Second edge, 323 First oblique edge, 33 Second wide region, 331 Third edge, 332 Fourth edge, 333 Second oblique edge, 34 Insulating tape, 35 Fixing tape, 40 negative electrode busbars

Claims

1. A conductor having a first portion having a first cross-sectional area and a second portion having a second cross-sectional area larger than the first cross-sectional area, and acting as a fuse, An insulating member that surrounds the first portion of the conductor but does not surround the second portion of the conductor, A bus bar equipped with a bus bar.

2. The bus bar according to claim 1, wherein the second portion is located on both sides of the first portion.

3. Battery cell and A busbar according to claim 1 or 2, electrically connected to the battery cell, A battery module equipped with the following features.

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