Busbar and battery module

Abstract

A positive electrode bus bar (300) is provided with: a fuse section (312) that extends in a prescribed direction; and an insulating material (320) that surrounds substantially the central portion of the fuse section (312) in the prescribed direction without surrounding both end portions of the fuse section (312) in the prescribed direction.

Description

Busbars and battery modules

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

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

[0003] Patent Document 1 describes a bus bar, which includes a fusible portion and a fireproof sleeve that covers the fusible portion.

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

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

[0006] Chinese Utility Model No. 219717185 Patent Publication No. 2022-534951 US Patent Application Publication No. 2014 / 0315051

[0007] As described in Patent Document 1, the fuse of the bus bar may be surrounded by an enclosing material such as a fire sleeve for reasons of heat insulation. However, when the fuse is surrounded by an enclosing material, the duration of arc discharge that occurs when the fuse blows may be longer. The longer the arc discharge duration, the more likely the area of ​​the bus bar that is blown tends to expand. The wider the area of ​​the bus bar that is blown, the more difficult it may be to prevent damage to components surrounding the fuse.

[0008] One object of the present invention is to quickly suppress arc discharge that occurs when a fuse is blown. Other objects of the present invention will become apparent from the description of this specification.

[0009] An aspect of the present invention is as follows: 1. A busbar comprising a fuse extending in a predetermined direction, and a surrounding material surrounding a substantially central portion of the fuse in the predetermined direction without surrounding either end portion of the fuse in the predetermined direction. 2. The busbar according to 1., wherein the surrounding material is an insulating material. 3. The busbar according to 1. or 2., wherein the surrounding material contains at least one of glass fiber, ceramic, and a silicon compound. 4. The busbar according to any one of 1. to 3., wherein the surrounding material is configured to maintain its shape from the start of melting of the fuse to the end of arc discharge that occurs as a result of melting of the fuse. 5. The busbar according to any one of 1. to 4., wherein the dimension of the surrounding material in the predetermined direction is less than the dimension of the fuse in the predetermined direction. 6. The busbar according to 1., wherein the dimension of the surrounding material in the predetermined direction is 50% or more of the dimension of the fuse in the predetermined direction. The busbar according to any one of claims 1 to 5. 7. The busbar according to any one of claims 1 to 6., wherein the duration of arc discharge caused by melting of the fuse is 13 milliseconds or less. 8. A battery module comprising: a battery cell; and the busbar according to any one of claims 1 to 7., electrically connected to the battery cell.

[0010] According to the above-described aspects of the present invention, arc discharge that occurs when a fuse is blown can be quickly suppressed.

[0011] 1 is a perspective view of a battery module according to an embodiment; FIG. 2 is a perspective view of a portion of a positive bus bar according to an embodiment; FIG. 3 is a cross section taken along line A-A in FIG. 2; FIG. 4 is a diagram illustrating a circuit model of arc discharge at a fuse portion of a positive bus bar according to an embodiment; FIG. 5 is a diagram illustrating arc discharge occurring in association with melting of a fuse portion according to an embodiment; FIG. 6 is a diagram illustrating arc discharge occurring in association with melting of a fuse portion according to an embodiment; FIG. 7 is a graph illustrating the time progression of current when a fuse portion of a bus bar according to Example 1 is melted; FIG. 8 is a graph illustrating the time progression of current when a fuse portion of a bus bar according to Example 2 is melted; and FIG. 9 is a graph illustrating the time progression of current when a fuse portion of a bus bar according to a comparative example is melted.

[0012] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, similar components are designated by similar reference numerals, and the description thereof will be omitted as appropriate.

[0013] FIG. 1 is a perspective view of a battery module 1 according to an embodiment.

[0014] For the purpose of explanation, arrows indicating the X, Y, and Z directions are shown in FIG. 1 . Hereinafter, unless otherwise specified, the tip of an arrow indicating the X direction will be referred to as the rear side of the battery module 1, and the base end of an arrow indicating the X direction will be referred to as 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. Hereinafter, unless otherwise specified, the tip of an arrow indicating the Y direction will be referred to as the left side of the battery module 1, and the base end of an arrow indicating the Y direction will be referred to as 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. Hereinafter, unless otherwise specified, the tip of an arrow indicating the Z direction will be referred to as the upper side of the battery module 1, and the base end of an arrow indicating the Z direction will be referred to as the lower side of the battery module 1. Hereinafter, unless otherwise specified, the +X side and the −X side respectively refer to the tip side and the base side of the arrow indicating the X direction, the +Y side and the −Y side respectively refer to the tip side and the base side of the arrow indicating the Y direction, and the +Z side and the −Z side respectively refer to the tip side and the base side of the arrow indicating the Z direction. Note that the relationship between each of the X direction, the Y direction, and the Z direction and each of the front-rear direction, the left-right direction, and the up-down direction of the battery module 1 is not limited to the above-mentioned example.

[0015] The structure of the battery module 1 will be described with reference to FIG.

[0016] The battery module 1 includes a cell stack 10 and a voltage detection device 20. The cell stack 10 includes a plurality of battery cells 100. The voltage detection device 20 detects the voltages of the plurality of battery cells 100. The voltage detection device 20 includes a holder 200, a plurality of voltage detection terminals 210, a positive bus bar 300, and a negative bus bar 400.

[0017] The plurality of battery cells 100 are stacked in the Y direction. The longitudinal direction of each battery cell 100 is approximately parallel to the X direction. The lateral direction of each battery cell 100 is approximately parallel to the Z direction. The thickness direction of each battery cell 100 is approximately parallel to the Y direction. The shape of each battery cell 100 is not limited to this example.

[0018] Each battery cell 100 includes a battery element (not shown), an exterior material 102, a positive electrode tab 104, and a negative electrode tab 106. 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 102 seals the battery element and an electrolyte (not shown). The positive electrode tab 104 is electrically connected to the positive electrode of the battery element. The positive electrode tab 104 is pulled out from one of both sides of the exterior material 102 in the X direction. The negative electrode tab 106 is electrically connected to the negative electrode of the battery element. The negative electrode tab 106 is pulled out from the other side of the exterior material 102 in the X direction. However, the structure of each battery cell 100 is not limited to this example.

[0019] Each battery cell 100 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 electrolytic solution. Unless otherwise specified, the following description will be given assuming that each battery cell 100 is a battery cell containing an electrolytic solution.

[0020] In this embodiment, the multiple battery cells 100 are electrically connected in a combination of series and parallel. Specifically, cell groups including at least two battery cells 100 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 cell stack 10, a positive electrode tab 104 drawn from a battery cell 100 of one cell group connected in parallel and a negative electrode tab 106 drawn from a battery cell 100 of another cell group connected in parallel are electrically connected to each other, forming a tab connection portion 108 including the positive electrode tab 104 and the negative electrode tab 106. The positive electrode tab 104 and the negative electrode tab 106 at the tab connection portion 108 are joined to each other by, for example, laser welding. A tab group is similarly formed on the +X side of the cell stack 10. Thus, multiple cell groups are connected in series from the cell group located at one end of the cell stack 10 in the Y direction to the cell group located at the other end of the cell stack 10 in the Y direction.

[0021] The electrical connection of the plurality of battery cells 100 is not limited to the above example. For example, the cell stack 10 may be configured by connecting single battery cells 100 in series.

[0022] The holder 200 is disposed on the −X side with respect to the cell stack 10. The holder 200 defines a plurality of openings 202. Each of the plurality of tab connection portions 108 is exposed toward the −X side through each of the plurality of openings 202. The holder 200 integrally holds a plurality of voltage detection terminals 210. Therefore, by placing the holder 200 in an appropriate position with respect to the cell stack 10, each of the plurality of voltage detection terminals 210 can be disposed in an appropriate position with respect to each of the plurality of tab connection portions 108.

[0023] The +X side surface of each voltage detection terminal 210 and the −X side surface of each tab connection portion 108 are joined to each other by a joining method such as laser welding. Thus, each voltage detection terminal 210 and each tab connection portion 108 are electrically connected to each other. Therefore, the voltage detection device 20 can detect the voltage of each tab connection portion 108 by each voltage detection terminal 210. Each voltage detection terminal 210 is electrically connected to a connector (not shown) via a voltage detection line such as a harness (not shown).

[0024] The positive electrode bus bar 300 is disposed at the end of the holding body 200 on the −Y side. The positive electrode bus bar 300 and the positive electrode tabs 104 drawn from the cell group located at the end of the −Y side of the cell stack 10 are electrically connected to each other. The positive electrode bus bar 300 functions as an external terminal for electrically connecting to an external device such as another battery module. The negative electrode bus bar 400 is disposed at the end of the holding body 200 on the +Y side. The negative electrode bus bar 400 and the negative electrode tabs 106 drawn from the cell group located at the end of the +Y side of the cell stack 10 are electrically connected to each other. The negative electrode bus bar 400 functions as an external terminal for electrically connecting to an external device such as another battery module.

[0025] A voltage detection device similar to voltage detection device 20 is also provided on the +X side of cell stack 10, except that it does not have positive electrode bus bar 300 and negative electrode bus bar 400. Therefore, it is possible to detect the voltages of multiple tab connections on the +X side of cell stack 10.

[0026] In the embodiment, the positive electrode tab 104 at the end of a group of multiple cells connected in series is a positive electrode tab 104 drawn toward the −X side from a battery cell 100 of a cell group located at the end on the −Y side of the cell stack 10, and the negative electrode tab 106 at the end of a group of multiple cells connected in series is a negative electrode tab 106 drawn toward the −X side from a battery cell 100 of a cell group located at the end on the +Y side of the cell stack 10. Thus, both the positive electrode bus bar 300 and the negative electrode bus bar 400 are disposed on the −X side of the battery cell 100. However, the arrangement of the positive electrode tab 104 and the negative electrode tab 106 at the end of a group of multiple cells connected in series may differ depending on the number of battery cells 100 included in the cell stack 10. For example, consider a case where the positive electrode tab 104 at the end of a group of multiple cells connected in series is the positive electrode tab 104 drawn out toward the +X side from the battery cell 100 of the cell group located at the end on the -Y side of the cell stack 10, and the negative electrode tab 106 at the end of a group of multiple cells connected in series is the negative electrode tab 106 drawn out toward the -X side from the battery cell 100 of the cell group located at the end on the +Y side of the cell stack 10. In this case, the positive electrode bus bar 300 is arranged on the +X side of the cell stack 10, and the negative electrode bus bar 400 is arranged on the -X side of the cell stack 10.

[0027] Fig. 2 is a perspective view of a portion of a positive bus bar 300 according to this embodiment. Fig. 3 is a cross section taken along the line A-A in Fig. 2. The matters described for the positive bus bar 300 with reference to Figs. 2 and 3 are similarly applicable to the negative bus bar 400, except that the positive bus bar 300 and the negative bus bar 400 have substantially symmetrical shapes.

[0028] In this embodiment, the positive bus bar 300 is made of copper. However, the positive bus bar 300 may be made of a metal other than copper. As shown in Figures 2 and 3 , the positive bus bar 300 includes an elongated conductor 310 and an insulating material 320.

[0029] The extended conductor 310 extends in the Y direction. The extended conductor 310 includes a fuse portion 312, a first extending portion 314, and a second extending portion 316. The fuse portion 312, the first extending portion 314, and the second extending portion 316 extend in the Y direction. The +Y side end of the fuse portion 312 and the −Y side end of the first extending portion 314 are electrically connected to each other. The −Y side end of the fuse portion 312 and the +Y side end of the second extending portion 316 are electrically connected to each other.

[0030] The fuse portion 312 is a fuse that can blow when an overcurrent of a certain value or more flows through the positive bus bar 300 due to factors such as an abnormality in the battery cell 100. The overcurrent at which the fuse portion 312 blows varies depending on the capacity of the battery module 1, but is, for example, approximately 6,000 A. In the example shown in FIG. 2 , the fuse portion 312 is defined by a notch 313 formed on the negative X-side edge of the extended conductor 310. Due to the notch 313, the X-direction dimension of the fuse portion 312 is less than both the X-direction dimension of the first extension portion 314 and the X-direction dimension of the second extension portion 316. Therefore, the cross-sectional area of ​​the fuse portion 312 perpendicular to the Y-direction is less than both the cross-sectional area of ​​the first extension portion 314 perpendicular to the Y-direction and the cross-sectional area of ​​the second extension portion 316 perpendicular to the Y-direction.

[0031] 2 , the method for making the cross-sectional area of ​​the fuse portion 312 perpendicular to the Y direction smaller than each of the cross-sectional areas of the first extension portion 314 perpendicular to the Y direction and the second extension portion 316 perpendicular to the Y direction is not limited to the example shown in FIG. 2 . For example, the notch 313 may be formed on the edge on the +X side of the extended conductor 310. Alternatively, the notch 313 may be formed on both edges of the extended conductor 310 in the Y direction. Alternatively, the dimension of the fuse portion 312 in the Z direction may be smaller than each of the dimension of the first extension portion 314 in the Z direction and the dimension of the second extension portion 316 in the Z direction.

[0032] 2 and 3 , the insulating material 320 is a surrounding material that surrounds the fuse portion 312 around the Y direction. As shown in FIG. 2 , the insulating material 320 surrounds an approximately central portion of the fuse portion 312 in the Y direction without surrounding both end portions of the fuse portion 312 in the Y direction. That is, the dimension of the insulating material 320 in the Y direction is less than the dimension of the fuse portion 312 in the Y direction. Therefore, both end portions of the fuse portion 312 in the Y direction are exposed from the insulating material 320. In the embodiment, compared to a case where no portion of the fuse portion 312 is surrounded by the insulating material 320, it is possible to improve the thermal insulation and electrical insulation between the fuse portion 312 and the surrounding area of ​​the fuse portion 312, thereby improving the reliability of operation of the fuse portion 312.

[0033] In the example shown in FIG. 3 , the insulating material 320 is arranged around the fuse portion 312 in the Y direction. For example, the insulating material 320 is an insulating tape wrapped around the fuse portion 312 in the Y direction. Alternatively, the insulating material 320 may be an insulating tube that surrounds the fuse portion 312 in the Y direction. In these examples, it is easier to surround the fuse portion 312 with a surrounding material around the Y direction than to arrange insulating blocks such as resin blocks around the fuse portion 312 in the Y direction or to coat the surface of the fuse portion 312 around the Y direction with an insulating layer such as a resin layer. The arrangement of the insulating material 320 is not limited to the example shown in FIG. 3 . Furthermore, the surrounding material that surrounds the fuse portion 312 around the Y direction may be an insulating block such as a resin block arranged around the fuse portion 312 in the Y direction or an insulating layer such as a resin layer that coats the surface of the fuse portion 312 around the Y direction.

[0034] The insulating material 320 has heat resistance that allows it to withstand heat generated during normal operation of the positive bus bar 300. The insulating material 320 does not have to withstand heat generated when the fuse portion 312 melts. For example, the insulating material 320 does not have to withstand temperatures equal to or higher than the melting point of 1085°C of copper that constitutes the fuse portion 312. However, the insulating material 320 may have fire resistance. If the insulating material 320 has fire resistance, the fire resistance of the fuse portion 312 can be improved. The insulating material 320 contains, for example, at least one of glass fiber, ceramic, and Si compound.

[0035] A fixing tape (not shown) may be wrapped around the fuse portion 312 in the Y direction, outside the insulating material 320. The fixing tape can assist in fixing the insulating material 320 to the fuse portion 312. The assistance of the fixing tape can prevent the insulating material 320 from shifting in position at the fuse portion 312 and also prevent the insulating material 320 from coming off the fuse portion 312.

[0036] 4 is a diagram showing a circuit model of arc discharge at the fuse portion 312 of the positive bus bar 300 according to this embodiment. The matters described with reference to FIG. 4 are applicable not only to the fuse portion 312 of the positive bus bar 300 but also to the fuse portion of the negative bus bar 400.

[0037] The inventors of the present application have found that when an overcurrent flows through the positive bus bar 300, the fuse portion 312 melts, and then an arc discharge may occur between the −Y side end of the first extension portion 314 and the +Y side end of the second extension portion 316. The longer the arc discharge duration, the more likely the melted area of ​​the positive bus bar 300 will expand. The wider the melted area of ​​the positive bus bar 300, the more difficult it may be to prevent damage to components around the fuse portion 312, such as portions of the positive bus bar 300 other than the fuse portion 312 and the portion of the holder 200 surrounding the fuse portion 312. Therefore, in order to prevent damage to components around the fuse portion 312, it is necessary to quickly reduce the duration of the arc discharge.

[0038] In the model shown in FIG. ０ indicates the voltage of the cell stack 10, and R ０ indicates the total resistance of all elements constituting the circuit of the battery module 1, such as the battery cells 100 and the wiring electrically connected to the battery cells 100, and V ａｒｃ indicates the arc voltage of the arc discharge occurring between the −Y side end of the first extension portion 314 and the +Y side end of the second extension portion 316. As shown in the model shown in FIG. 4, the length L of the arc discharge ａｒｃ In this case, the arc voltage V ａｒｃ consists of the anode fall voltage, cathode fall voltage and arc column voltage. In order to suppress the arc discharge, the arc voltage V ａｒｃ is the voltage V ０ From the model shown in Figure 4, it is necessary to increase the resistance of the arc discharge in order to suppress the arc discharge.

[0039] 5 to 7 are diagrams illustrating arc discharge EA that occurs when fuse portion 312 according to this embodiment melts. Figures 5 to 7 are schematic cross-sections perpendicular to the X direction at approximately the center of fuse portion 312 and insulating material 320 in the X direction. The matters described with reference to Figures 5 to 7 are applicable not only to fuse portion 312 of positive bus bar 300, but also to fuse portions of negative bus bar 400.

[0040] First, as shown in FIG. 5, before the fuse portion 312 is blown, the insulating material 320 surrounds the approximate center portion of the fuse portion 312 in the Y direction without surrounding both end portions of the fuse portion 312 in the Y direction.

[0041] Next, as shown in FIG. 6 , when an overcurrent flows through the positive bus bar 300, the fuse portion 312 melts, and an arc discharge EA occurs between the −Y side end of the first extension portion 314 and the +Y side end of the second extension portion 316 through the space surrounded by the insulating material 320 in the Y direction.

[0042] The melting of the fuse portion 312 generates a force that repels objects around the fuse portion 312. As shown in FIG. 5 , before the fuse portion 312 melts, the insulating material 320 surrounds the approximate center portion of the fuse portion 312 in the Y direction, without surrounding both ends of the fuse portion 312 in the Y direction. Therefore, before the fuse portion 312 melts, the insulating material 320 is not supported by both ends of the fuse portion 312 in the Y direction. Therefore, as shown in FIG. 7 , when the fuse portion 312 melts, the insulating material 320 is repelled from the position where the fuse portion 312 was located. In the example shown in FIG. 7 , the insulating material 320 is repelled toward the +Z side from the position where the fuse portion 312 was located. However, the direction in which the insulating material 320 is repelled is not limited to the direction shown in FIG. 7 and varies depending on the manner in which the fuse portion 312 melts.

[0043] The insulating material 320 has durability, such as strength and heat resistance, such that even if the insulating material 320 is blown away by the melting of the fuse portion 312, the surrounding shape of the insulating material 320 is substantially maintained as it was when the fuse portion 312 was present. Therefore, as shown in FIG. 7 , even if the insulating material 320 is blown away by the melting of the fuse portion 312, the surrounding shape of the insulating material 320 is substantially maintained. Therefore, as shown in FIG. 7 , when the insulating material 320 is blown away, an arc discharge EA occurs through the space surrounded by the insulating material 320 between the −Y side end of the first extension portion 314 and the +Y side end of the second extension portion 316. The insulating material 320 has durability, such as strength and heat resistance, such that the surrounding shape of the insulating material 320 is substantially maintained from the start of melting of the fuse portion 312 to the end of the arc discharge EA. That is, the insulating material 320 is configured so that the shape of the insulating material 320 is substantially maintained from the start of melting of the fuse portion 312 to the end of the arc discharge EA.

[0044] In the embodiment, compared to when the insulating material 320 surrounds the entire Y-direction of the fuse portion 312 before the fuse portion 312 melts, the ambient low-temperature air flows into the space between the −Y-side end of the first extension portion 314 and the +Y-side end of the second extension portion 316, thereby restoring the dielectric strength of the space and increasing the resistance to arc discharge. Therefore, in the embodiment, compared to when the insulating material 320 surrounds the entire Y-direction of the fuse portion 312 before the fuse portion 312 melts, the arc discharge can be suppressed more quickly.

[0045] There is no particular limitation on the Y-direction dimension of the insulating material 320. In one example, from the viewpoint of facilitating the flow of ambient low-temperature air into the space between the −Y-side end of the first extension portion 314 and the +Y-side end of the second extension portion 316, it is preferable that the Y-direction dimension of the insulating material 320 be a ratio of a certain value or less to the Y-direction dimension of the fuse portion 312. Alternatively, the Y-direction dimension of the insulating material 320 may be, for example, 50% or more of the Y-direction dimension of the fuse portion 312. When the Y-direction dimension of the insulating material 320 is 50% or more of the Y-direction dimension of the fuse portion 312, the distance from the −Y-side end of the first extension portion 314 and the +Y-side end of the second extension portion 316 to the first extension portion 314 can be shortened when the insulating material 320 is flipped off as shown in Fig. 7, compared to when the Y-direction dimension of the insulating material 320 is less than 50% of the Y-direction dimension of the fuse portion 312. This makes it easier to confine the arc discharge EA within the area surrounded by the insulating material 320. Therefore, compared to when the arc discharge EA is generated outside the area surrounded by the insulating material 320, when the insulating material 320 is flipped off as shown in Fig. 7, the arc discharge EA can be more easily interrupted from the −Y-side end of the first extension portion 314 and the +Y-side end of the second extension portion 316, making it easier to shorten the duration of the arc discharge EA. Furthermore, when the Y-direction dimension of the insulating material 320 is 50% or more of the Y-direction dimension of the fuse portion 312, the strength of the insulating material 320 can be improved compared to when the Y-direction dimension of the insulating material 320 is less than 50% of the Y-direction dimension of the fuse portion 312, and it is easier to maintain the surrounding shape of the insulating material 320 even if the insulating material 320 is blown away, as shown in Figure 7.

[0046] Fig. 8 is a graph showing the change in current over time when the fuse portion of the bus bar according to Example 1 is blown. Fig. 9 is a graph showing the change in current over time when the fuse portion of the bus bar according to Example 2 is blown. Fig. 10 is a graph showing the change in current over time when the fuse portion of the bus bar according to the comparative example is blown. In the graphs shown in Figs. 8 to 10, the horizontal axis represents time (unit: seconds) and the vertical axis represents current (unit: A).

[0047] The bus bar according to Example 1 has a fuse portion. The fuse portion extends in a predetermined extension direction. The dimension of the fuse portion in the extension direction is 20 mm. A ceramic glass tape is wound around the fuse portion in the extension direction of the fuse portion. The tape according to Example 1 surrounds an approximately central portion of the fuse portion in the extension direction of the fuse portion without surrounding either end portion of the fuse portion in the extension direction. In other words, the dimension of the tape according to Example 1 in the extension direction of the fuse portion is less than the dimension of the fuse portion. The dimension of the fuse portion of the tape according to Example 1 in the extension direction is 10 mm. The bus bar according to Example 1 corresponds to the positive bus bar 300 according to the embodiment. The fuse portion according to Example 1 corresponds to the fuse portion 312 according to the embodiment. The tape according to Example 1 corresponds to the insulating material 320 according to the embodiment. The extension direction according to Example 1 corresponds to the Y direction according to the embodiment.

[0048] The bus bar according to the second embodiment is similar to the bus bar according to the first embodiment, except that instead of the ceramic glass tape, a glass fiber tape is wound around the fuse portion in the extension direction of the fuse portion.

[0049] The bus bar according to the comparative example is similar to the bus bar according to the first example, except that instead of the tape according to the first example, a silicone- and aluminum-coated glass fiber tape surrounds not only the fuse portion but also the extension portions located on both sides of the fuse portion of the bus bar in the extension direction of the fuse portion. That is, the dimension of the tape according to the comparative example is larger than the dimension of the fuse portion in the extension direction of the fuse portion. The dimension of the fuse portion of the tape according to the comparative example in the extension direction is 30 mm. The extension portions according to the comparative example correspond to the first extension portion 314 and the second extension portion 316 according to the embodiment.

[0050] In the graphs shown in Figures 8, 9, and 10, melting of the fuse portion began at approximately 0.15 seconds, and the current decreased. The arc discharge time can be estimated as the time from when the current began to decrease due to melting of the fuse portion to when the current decreased to 0. Note that the rise in current near 0 seconds in the graphs shown in Figures 8, 9, and 10 indicates the start-up of the test equipment.

[0051] 8, in the bus bar according to Example 1, the current dropped to 0 almost immediately after the fuse portion started to melt at about 0.15 seconds. Therefore, it can be said that the arc discharge time was almost zero in the bus bar according to Example 1.

[0052] 9 , in the bus bar according to Example 2, the current dropped to 0 in about 13 milliseconds from the time when the fuse portion started to melt around 0.15 seconds. Therefore, it can be said that the arc discharge time in the bus bar according to Example 2 was about 13 milliseconds.

[0053] 10 , in the bus bar according to the comparative example, the current dropped to 0 approximately 116 milliseconds after the fuse portion started to melt around 0.15 seconds. Therefore, it can be said that the arc discharge duration in the bus bar according to the comparative example was approximately 116 milliseconds.

[0054] From the results shown in Figures 8 to 10, it can be said that arc discharge can be quickly suppressed by having the insulating material surround approximately the center portion of the fuse portion in the extension direction rather than surrounding both end portions of the fuse portion in the extension direction.

[0055] Although the embodiments of the present invention have been described above with reference to the drawings, these are merely examples of the present invention, and various other configurations can also be adopted.

[0056] This application claims priority based on Japanese Patent Application No. 2024-060116, filed April 3, 2024, the disclosure of which is incorporated herein by reference in its entirety.

[0057] REFERENCE SIGNS LIST 1 Battery module, 10 Cell stack, 20 Voltage detection device, 100 Battery cell, 102 Exterior material, 104 Positive electrode tab, 106 Negative electrode tab, 108 Tab connection portion, 200 Holder, 202 Opening, 210 Voltage detection terminal, 300 Positive electrode bus bar, 310 Extended conductor, 312 Fuse portion, 313 Notch, 314 First extension portion, 316 Second extension portion, 320 Insulating material, 400 Negative electrode bus bar

Claims

1. A busbar comprising: a fuse extending in a predetermined direction; and a surrounding material surrounding an approximate center portion of the fuse in the predetermined direction but not surrounding either end portion of the fuse in the predetermined direction.

2. The busbar according to claim 1, wherein the surrounding material is an insulating material.

3. The bus bar according to claim 1, wherein the surrounding material contains at least one of glass fiber, ceramic, and silicon compound.

4. The bus bar according to claim 1, wherein the surrounding material is configured so that the shape of the surrounding material is substantially maintained from the start of melting of the fuse to the end of arc discharge that occurs as the fuse melts.

5. The busbar according to claim 1, wherein the dimension of the surrounding material in the predetermined direction is less than the dimension of the fuse in the predetermined direction.

6. The bus bar according to claim 1, wherein the dimension of the surrounding material in the predetermined direction is 50% or more of the dimension of the fuse in the predetermined direction.

7. The bus bar according to claim 1, wherein the duration of arc discharge that occurs when the fuse blows is 13 milliseconds or less.

8. A battery module comprising: a battery cell; and a bus bar according to any one of claims 1 to 7, electrically connected to the battery cell.

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