Battery module

Abstract

To provide a battery module with high reliability.SOLUTION: A battery module includes: a first battery; a second battery; a busbar including a first part disposed over the first battery and the second battery and connected to a first terminal of the first battery, a second part connected to a second terminal of the second battery, and a fusion part that exists between the first part and the second part and can be melted with a smaller current than a current that melts the first part and the second part; and a cover member including a cover part provided below the busbar, covering the first battery and the second battery, and exposing the first terminal and the second terminal, and a support part that is provided on the cover part, supports the first part so that, in a state where the fusion part is melted and the first part and the second part are separated, a position of an end part of the first part that is the closest to the second part becomes higher than a position of an end part of the second part that is the closest to the first part.SELECTED DRAWING: Figure 4

Description

[Technical Field]

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

[0002] When two batteries are electrically connected by a bus bar, the bus bar may be provided with a fusing portion that melts when a current greater than a predetermined amount flows through it. When a current greater than a predetermined amount flows through the bus bar, the fusing portion melts. This separates the portion of the bus bar connected to one of the two batteries from the portion connected to the other. In this way, the fusing portion functions as a fuse, preventing a current greater than a predetermined amount from flowing from one of the two batteries to the other. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Application No. 2019-546686 Summary of the Invention [Problem to be solved by the invention]

[0004] The problem to be solved by the present invention is to provide a highly reliable battery module. [Means for solving the problem]

[0005] a flexible bus bar arranged above the first and second batteries and including a first portion connected to the first terminal, a second portion connected to the second terminal, and a fusing portion located between the first and second portions, connected to the first and second portions, and meltable with a current lower than the current at which the first and second portions melt; a cover portion provided below the bus bar, covering the first and second batteries and exposing the first and second terminals; and an insulating cover member including a support portion provided on the cover portion and supporting the first portion so that, when the fusing portion melts and the first and second portions are separated, the position of the end of the first portion closest to the second portion is higher than the position of the end of the second portion closest to the first portion. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a perspective view showing a battery module according to a first embodiment. [Figure 2] 2 is an exploded perspective view showing a plurality of batteries and a housing in the battery module of FIG. 1. FIG. [Figure 3] FIG. 2 is a perspective view showing a battery in the battery module of FIG. [Figure 4] FIG. 4(a) is a cross-sectional view taken along line IV-IV in FIG. 1, showing the state before the fusion portion of the bus bar melts, and FIG. 4(b) is a cross-sectional view showing the state after the fusion portion melts. [Figure 5] FIG. 5(a) is an enlarged top view of the vicinity of the bus bar in FIG. 1, FIG. 5(b) is a cross-sectional view showing another example of the bus bar, and FIG. 5(c) is a cross-sectional view showing another example of the bus bar. [Figure 6] FIG. 6(a) is a cross-sectional view showing a state before a fusing portion of a bus bar in the second embodiment melts, and FIG. 6(b) is a cross-sectional view showing a state after the fusing portion melts. [Figure 7]FIG. 7(a) is a cross-sectional view showing a state before a fusion portion of a bus bar in the third embodiment melts, and FIG. 7(b) is a cross-sectional view showing a state after the fusion portion melts. DETAILED DESCRIPTION OF THE INVENTION

[0007] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between parts, etc. are not necessarily the same as those in reality. Even when the same part is shown, the dimensions and ratios may be different depending on the drawing. In the present specification and the drawings, elements similar to those already explained are given the same reference numerals and detailed explanations will be omitted as appropriate.

[0008] For ease of explanation, the following uses an XYZ Cartesian coordinate system. The arrow direction in the Z direction is referred to as the "upward direction," and the opposite direction is referred to as the "downward direction." The upward direction is the opposite direction to the direction of gravity.

[0009] First Embodiment First, the first embodiment will be described. FIG. 1 is a perspective view showing a battery module according to this embodiment. FIG. 2 is an exploded perspective view showing a plurality of batteries and a housing in the battery module of FIG. FIG. 3 is a perspective view showing a battery in the battery module of FIG. FIG. 4(a) is a cross-sectional view taken along line IV-IV in FIG. 1, showing the state before the fusion portion of the bus bar melts, and FIG. 4(b) is a cross-sectional view showing the state after the fusion portion melts. FIG. 5(a) is an enlarged top view of the vicinity of the bus bar in FIG. 1, FIG. 5(b) is a cross-sectional view showing another example of the bus bar, and FIG. 5(c) is a cross-sectional view showing another example of the bus bar. The battery module 100 according to this embodiment includes a plurality of batteries 110, a housing 120, and a plurality of bus bars 130. Each part of the battery module 100 will be described in detail below.

[0010] Each battery 110 is a secondary battery such as a lithium ion battery, etc. As shown in Fig. 3, each battery 110 includes a power generating element 111, a battery casing 112, and two terminals 113a.

[0011] The power generating element 111 includes, for example, a positive electrode layer, a negative electrode layer, and a separator provided between the positive electrode layer and the negative electrode layer.

[0012] The battery casing 112 houses the power generating element 111. The shape of the battery casing 112 is, for example, approximately cubic.

[0013] One of the two terminals 113a is electrically connected to one of the positive electrode layer and the negative electrode layer of the power generating element 111. The other of the two terminals 113a is electrically connected to the other of the positive electrode layer and the negative electrode layer of the power generating element 111. At least a portion of each terminal 113a protrudes above the upper surface of the battery casing 112. A lower portion of each terminal 113a may be inserted into the battery casing 112. Alternatively, the entirety of each terminal 113a may be disposed on the upper surface of the battery casing 112. In this case, each terminal 113a is electrically connected to the positive electrode layer or the negative electrode layer via a conductive member.

[0014] 1 and 2, the housing 120 includes a housing member 121 that houses at least some of the batteries 110, and a cover member 122 that is provided on the housing member 121 and covers the batteries 110. The shape of the housing 120 is, for example, a substantially cubic shape when the cover member 122 is attached to the housing member 121. The housing 120 can be made of an insulating material with excellent heat resistance, such as polycarbonate or modified polyphenylene ether resin. In other words, the housing 120 including the cover member 122 has insulating properties.

[0015] As shown in FIG. 2, the housing member 121 includes, for example, a bottom plate portion 121a and four side plate portions 121b. The upper and lower surfaces of the bottom plate portion 121a are generally parallel to the XY plane. When viewed from above, the bottom plate portion 121a has a generally rectangular shape with two of the four sides of its periphery parallel to the X direction and the other two sides parallel to the Y direction. Each side plate portion 121b extends upward from each side of the periphery of the bottom plate portion 121a. A space capable of housing the lower portions of the multiple batteries 110 is formed inside the bottom plate portion 121a and the four side plate portions 121b. However, the shape of the housing member is not limited to the above shape as long as it can accommodate multiple batteries. The housing member may also house other components besides batteries, such as a circuit for controlling the batteries.

[0016] The plurality of batteries 110 are arranged in rows and columns in the X and Y directions within the housing member 121. For example, the upper portions of the plurality of batteries 110 are exposed from the housing member 121. Note that FIGS. 1 and 2 show an example in which 18 batteries 110 are provided within the housing member 121. However, the number of batteries provided within the housing member is not limited to the above. Furthermore, the arrangement of the plurality of batteries is not limited to the arrangement shown in FIGS. 1 and 2.

[0017] The cover member 122 includes, for example, a cover portion 122a, four side plate portions 122b, and a plurality of support portions 122c.

[0018] The cover portion 122a is positioned above the plurality of batteries 110 and covers the plurality of batteries 110. The upper and lower surfaces of the cover portion 122a are, for example, approximately parallel to the XY plane. When viewed from above, the cover portion 122a has a generally rectangular shape with two of the four sides of its periphery parallel to the X direction and the other two sides parallel to the Y direction. The cover portion 122a has a plurality of through holes 122h that expose the terminals 113a of each battery 110. Each side plate portion 122b extends downward from each side of the outer periphery of the cover portion 122a.

[0019] Each support portion 122c is provided on the cover portion 122a. Each support portion 122c is located below at least one bus bar 130. In this embodiment, one support portion 122c is located below multiple bus bars 130. However, a support portion may be provided individually below each bus bar.

[0020] In the following, an example will be described in which each bus bar 130 electrically connects two batteries 110 adjacent to each other in the X direction, as shown in FIG. 1 . One of the two batteries 110 electrically connected by each bus bar 130 is referred to as the “first battery 110c1,” and the other is referred to as the “second battery 110c2.” The terminal 113a of the first battery 110c1 connected to the bus bar 130 is referred to as the “first terminal 113a1.” The terminal 113a of the second battery 110c2 connected to the bus bar 130 is referred to as the “second terminal 113a2.” Note that in FIGS. 4(a) and 4(b), the lower portion of the terminal 113a of each battery 110 is simply and integrally illustrated. The same applies to other cross-sectional views. However, the first battery and the second battery connected by the bus bar do not necessarily need to be arranged adjacent to each other. For example, other components of the battery module may be interposed between the first battery and the second battery. Furthermore, the first battery and second battery connected by the bus bar may be arranged adjacent to each other in other directions, such as the Y direction.

[0021] As shown in FIG. 4(a), in this embodiment, each support portion 122c includes a first protrusion 123 and a second protrusion 124. The first protrusion 123 and the second protrusion 124 each protrude upward from the cover portion 122a. The position of the upper end 123t of the first protrusion 123 in the up-down direction is higher than the position of the upper end 124t of the second protrusion 124. The first protrusion 123 is disposed above the first battery 110c1. The second protrusion 124 is disposed above the second battery 110c2. However, if the first battery and the second battery are not disposed adjacent to each other, the first protrusion does not have to be disposed above the first battery, and the second protrusion does not have to be disposed above the second battery.

[0022] 2, in this embodiment, the first protrusions 123 and the second protrusions 124 each extend in the Y direction. Therefore, the first protrusions 123 and the second protrusions 124 are each located above the multiple batteries 110 lined up in the Y direction.

[0023] Each bus bar 130 is flexible. Each bus bar 130 is, for example, a metal foil. The thickness of each bus bar 130 is, for example, 0.1 mm or more and 0.3 mm or less. As shown in FIGS. 4(a) and 5(a), each bus bar 130 includes a first portion 131, a second portion 132, and a fusion portion 133. The first portion 131 is connected to the first terminal 113a1. The second portion 132 is connected to the second terminal 113a2. The fusion portion 133 is located between the first portion 131 and the second portion 132 and is continuous with the first portion 131 and the second portion 132. In this embodiment, the width L3 of the fusion portion 133 is smaller than the width L1 of the first portion 131 and the width L2 of the second portion 132. Therefore, the fusing portion 133 can be melted with a current lower than the current at which the first portion 131 and the second portion 132 melt.

[0024] Note that the fusing portion 133 may be configured by other methods so as to melt at a current lower than the current at which the first portion 131 and the second portion 132 melt. For example, as shown in FIG. 5(b), the thickness t3 of the fusing portion 133 may be smaller than the thickness t1 of the first portion 131 and the thickness t2 of the second portion 132. Alternatively, as shown in FIG. 5(c), the fusing portion 133 may be formed from a material that melts at a current lower than the current at which the materials of the first portion 131 and the second portion 132 melt. The configuration shown in FIG. 5(b) or 5(c) also allows the fusing portion 133 to melt at a current lower than the current at which the first portion 131 and the second portion 132 melt.

[0025] 4(a), each bus bar 130 is connected to first terminal 113a1 and second terminal 113a2 in a state where it is bent in a convex shape facing upward, for example. Specifically, when connected to first terminal 113a1 and second terminal 113a2, each bus bar 130 has a shape that is curved in a convex shape facing upward, with fusing portion 133 as its apex. In this state, first portion 131 is in contact with first protrusion 123, and second portion 132 is separated from second protrusion 124. However, the first portion may be separated from the first protrusion, and the second portion may be in contact with the second protrusion.

[0026] 5(a), when viewed from above, a part of first portion 131 overlaps with first protrusion 123. When viewed from above, a part of second portion 132 overlaps with second protrusion 124. When viewed from above, fusing portion 133 is located between first protrusion 123 and second protrusion 124.

[0027] Next, a method of using the battery module 100 according to this embodiment will be described. When a current equal to or greater than a predetermined amount flows through the bus bar 130, the fusing portion 133 melts. As shown in FIG. 4(b), the melting of the fusing portion 133 causes the first portion 131 and the second portion 132 to separate. The separated first portion 131 is supported by the first protrusion 123. The separated second portion 132 falls due to gravity and is supported by the second protrusion 124. As a result, the position of the end 131t of the first portion 131 closest to the second portion 132 is higher than the position of the end 132t of the second portion 132 closest to the first portion 131. As a result, contact between the first portion 131 and the second portion 132 can be suppressed after the melting of the fusing portion 133.

[0028] In particular, the battery module 100 may vibrate depending on how it is used, such as when mounted on a vehicle. In such cases, the positional relationship between the first battery 110c1 and the second battery 110c2 may change. If the positional relationship between the first battery 110c1 and the second battery 110c2 changes, the positional relationship between the separated first portion 131 and the second portion 132 may also change. Even if the positional relationship between the separated first portion 131 and the second portion 132 changes, contact between the first portion 131 and the second portion 132 can be prevented by setting the position of the end 131t of the first portion 131 closest to the second portion 132 higher than the position of the end 132t of the second portion 132 closest to the first portion 131.

[0029] Furthermore, at least a portion of the melted fusing portion 133 may fall due to gravity. In this case, the fallen portion of fusing portion 133 is positioned on cover portion 122a. This prevents the fallen portion of fusing portion 133 from entering housing 120. As a result, it is possible to prevent the fallen portion of fusing portion 133 from coming into contact with other components inside housing 120, such as battery 110 or the control circuit for battery 110.

[0030] Furthermore, when viewed from above, fusing portion 133 is located between first protrusion 123 and second protrusion 124, and therefore when melted, fusing portion 133 is likely to fall between first protrusion 123 and second protrusion 124. This prevents the fallen portion of fusing portion 133 from moving over cover portion 122a and entering housing 120 through through-hole 112h or the like when battery module 100 is vibrated or the like.

[0031] Next, the effects of this embodiment will be described. The battery module 100 according to this embodiment includes a cover member 122. The cover member 122 includes a cover portion 122a and a support portion 122c. The cover portion 122a is provided below the bus bar 130, covers the first battery 110c1 and the second battery 110c2, and exposes the first terminal 113a1 and the second terminal 113a2. The support portion 122c is provided on the cover portion 122a, and supports the first portion 131 so that, when the fusing portion 133 melts and the first portion 131 and the second portion 132 are separated, the position of the end 131t of the first portion 131 closest to the second portion 132 is higher than the position of the end 132t of the second portion 132 closest to the first portion 131. This prevents the first portion 131 and the second portion 132 from coming into contact with each other after the fusing portion 133 melts. Furthermore, the cover member 122 can prevent the fallen portion of the fusing portion 133 from coming into contact with the first battery 110c1 and the second battery 110c2, thereby providing a highly reliable battery module 100.

[0032] Furthermore, support portion 122c includes first protrusion 123 that protrudes upward from cover portion 122a and is located below first portion 131, and second protrusion 124 that protrudes from cover portion 122a toward bus bar 130 and is located below second portion 132, with upper end 124t positioned lower than upper end 123t of first protrusion 123. Therefore, when fusing portion 133 melts and first portion 131 and second portion 132 are separated, end 131t of first portion 131 that is closest to second portion 132 can be positioned higher than end 132t of second portion 132 that is closest to first portion 131.

[0033] Furthermore, when fusion portion 133 is not melted, fusion portion 133 is located between first protrusion 123 and second protrusion 124 when viewed from above. This makes it easy for fusion portion 133 to fall between first protrusion 123 and second protrusion 124 when it melts. Therefore, when battery module 100 is vibrated, for example, the fallen part of fusion portion 133 can be prevented from moving over cover portion 122a and entering housing 120.

[0034] Furthermore, when the fusing portion 133 is not melted, the second portion 132 is separated from the support portion 122c. Therefore, when the fusing portion 133 is melted, the position of the end 132t of the second portion 132 that is closest to the first portion 131 can be lowered.

[0035] Furthermore, the bus bar 130 is made of metal foil. Therefore, even if the positional relationship between the first battery 110c1 and the second battery 110c2 changes due to vibration of the battery module 100 or the like, the bus bar 130 can deform to follow the change in positional relationship. This can prevent loads from being applied to the connection between the bus bar 130 and the first battery 110c1 or the connection between the bus bar 130 and the second battery 110c2. Furthermore, because such a bus bar 130 is easily deformed, when the fusing portion 133 melts and the first portion 131 and the second portion 132 are separated, the second portion 132 can easily fall by utilizing gravity.

[0036] <Second embodiment> Next, a second embodiment will be described. FIG. 6(a) is a cross-sectional view showing the state before the fusing portion of the bus bar in this embodiment melts, and FIG. 6(b) is a cross-sectional view showing the state after the fusing portion has melted. A cover member 222 in this embodiment differs from the cover member 122 in the first embodiment in the shape of a support portion 222c.

[0037] Support portion 222c protrudes upward from cover portion 122a. A step 225 is provided on the upper surface of support portion 222c so that surface 225a facing first portion 131 is higher than surface 225b facing second portion 132. When fusing portion 133 melts and first portion 131 and second portion 132 separate, first portion 131 is supported by surface 225a, and second portion 132 is supported by surface 225b. The fallen portion of fusing portion 133 is placed on surface 225a or surface 225b.

[0038] Therefore, even with this configuration, when the fusing portion 133 melts and the first portion 131 and the second portion 132 are separated, the position of the end portion 131t of the first portion 131 closest to the second portion 132 can be made higher than the position of the end portion 132t of the second portion 132 closest to the first portion 131.

[0039] Furthermore, support portion 222c is disposed below fusing portion 133. This prevents heat from the fallen portion of fusing portion 133 from being transmitted to first battery 110c1, second battery 110c2, and the like.

[0040] <Third embodiment> Next, a third embodiment will be described. FIG. 7(a) is a cross-sectional view showing the state before the fusing portion of the bus bar in this embodiment melts, and FIG. 7(b) is a cross-sectional view showing the state after the fusing portion has melted. A cover member 322 in this embodiment differs from the cover member 122 in the first embodiment in the shape of a support portion 322c.

[0041] Support portion 322c consists solely of protrusion 323 provided below first portion 131 of bus bar 130. When fusing portion 133 melts and first portion 131 and second portion 132 are separated, first portion 131 is supported by protrusion 323, and second portion 132 is supported by cover portion 122a.

[0042] Even with this configuration, when the fusing portion 133 melts and the first portion 131 and the second portion 132 are separated, the position of the end 131t of the first portion 131 closest to the second portion 132 can be made higher than the position of the end 132t of the second portion 132 closest to the first portion 131.

[0043] In the above embodiments, an example has been described in which the cover member functions as an outer lid of the housing. However, the housing may include a housing member that houses multiple batteries and a lid member provided on the housing member, and the cover member may be disposed between the lid member and the multiple batteries. In other words, the cover member may function as an inner lid.

[0044] As described above, according to the embodiment, a highly reliable battery module is provided.

[0045] Although several embodiments of the present invention have been described above, these embodiments are presented by way of example only and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, modifications, etc. can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as set forth in the claims. Furthermore, the above-described embodiments can be implemented in combination with each other. [Explanation of symbols]

[0046] 100: Battery module 110:Battery 110c1: 1st battery 110c2: 2nd battery 111: Power generation element 112: Battery housing 112h:Through hole 113a:Terminal 113a1: 1st terminal 113a2: 2nd terminal 120: Housing 121: Storage member 121a: Bottom plate part 121b: Side plate part 122, 222, 322: Cover members 122a: Cover part 122b: Side plate part 122c, 222c, 322c: Support part 122h: Through hole 123: 1st protrusion 123t:Top end 124: 2nd protrusion 124t:Top end 130: Busbar 131 :1st part 131t: End 132:Second part 132t: End 133:Fusing part 225: Step 225a :face 225b :face 323: Protrusion

Claims

1. a first battery including a first terminal; a second battery including a second terminal; a flexible bus bar disposed above the first battery and the second battery, the bus bar including: a first portion connected to the first terminal; a second portion connected to the second terminal; and a fusing portion located between the first portion and the second portion, connected to the first portion and the second portion, and meltable with a current lower than a current at which the first portion and the second portion melt; a cover member having insulating properties, the cover member including: a cover portion provided below the bus bar, covering the first battery and the second battery and exposing the first terminal and the second terminal; and a support portion provided on the cover portion, supporting the first portion such that, when the fusing portion melts and the first portion and the second portion are separated, a position of an end of the first portion closest to the second portion is higher than a position of an end of the second portion closest to the first portion; A battery module comprising:

2. The support portion is a first protrusion that protrudes upward from the cover portion and is located below the first portion; a second protrusion that protrudes upward from the cover portion, is located below the second portion, and has an upper end positioned lower than an upper end position of the first protrusion; The battery module of claim 1 .

3. The battery module according to claim 2 , wherein the fusing portion is located between the first protrusion and the second protrusion when viewed from above in an unmelted state.

4. The support portion protrudes upward from the cover portion, The battery module according to claim 1 , wherein the upper surface of the support portion is provided with a step such that the surface facing the first portion is higher than the surface facing the second portion.

5. 5. The battery module according to claim 1, wherein the bus bar is bent upward in a convex shape when the fusing portion is not melted.

6. 6. The battery module according to claim 1, wherein the second portion is spaced apart from the support portion when the fusing portion is not melted.

7. 7. The battery module according to claim 1, wherein the bus bar is made of a metal foil.

Images