Battery module

Abstract

A battery module includes: a battery stack in which a plurality of batteries having output terminals (12) are arranged; and a bus bar (4) that electrically connects the plurality of batteries by engaging with the output terminals (12) of the respective batteries. The output terminal (12) has a probe mark (18) on a surface opposite the bus bar (4), and the bus bar (4) has a recess (22) opposite the probe mark (18).

Description

TECHNICAL FIELD

[0001] The present application relates to a battery module. BACKGROUND

[0002] For example, as a power source that requires a high output voltage such as for a vehicle, a battery module in which a plurality of secondary batteries are electrically connected is known. In the battery module, adjacent batteries are electrically connected via a bus bar. In addition, in a manufacturing process of the secondary battery, for example as disclosed in Patent Literature 1, a probe is brought into contact with an output terminal of the secondary battery, and charging and discharging of the secondary battery, inspection are performed.

[0003] [Patent Literature]

[0004] [Patent Literature]

[0005] Patent Literature 1: Japanese Patent Application Laid-Open No. 2004-319334 SUMMARY

[0006] [Problems to be Solved by the Invention]

[0007] In order to correctly and safely perform charging and discharging, inspection, it is desirable to reduce the contact resistance between the output terminal and the probe. As a method of reducing the contact resistance, a method is known in which the probe is pressed against the output terminal with a strong force, and the resistance of the oxide film on the surface of the terminal is removed or the contact area is increased by causing the probe to sink into the output terminal. However, if the probe is pressed against the output terminal, sometimes a trace of the probe is attached to the output terminal. The trace of the probe attached to the output terminal becomes a cause of reducing the connection reliability of the output terminal to the bus bar.

[0008] The present disclosure was completed in view of such a situation, and one of the objects thereof is to provide a technology that improves the connection reliability of an output terminal of a battery to a bus bar.

[0009] [Technical Solution for Solving the Technical Problem]

[0010] One aspect of the present disclosure is a battery module. The battery module includes: a battery stack in which a plurality of batteries each having an output terminal are arranged; and a bus bar that electrically connects the plurality of batteries by engaging with the output terminal of each battery. The output terminal has a trace of a probe on a surface opposite to the bus bar, and the bus bar has a recess portion opposite to the trace of the probe.

[0011] Another aspect of the present disclosure is also a battery module. The battery module includes: a battery stack in which a plurality of batteries each having an output terminal are arranged; and a bus bar that electrically connects the plurality of batteries by engaging with the output terminal of each battery. The output terminal has: an engagement surface with the bus bar, a recess portion recessed in a direction away from the bus bar than the engagement surface, and a trace of a probe disposed in the recess portion.

[0012] Furthermore, any combination of the above-described structural elements, and a scheme of converting the embodiments of the present disclosure between a method, a device, a system, and the like, are also effective as the embodiments of the present disclosure.

[0013] [Effect of Invention]

[0014] According to the present disclosure, it is possible to improve the connection reliability of the output terminal of the battery and the bus bar. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is a perspective view of a portion of a battery module of Embodiment 1.

[0016] Figure 2 is a cross-sectional view of a portion of an output terminal and a bus bar included in the battery module of Embodiment 1.

[0017] Figure 3 is a cross-sectional view of a portion of an output terminal and a bus bar included in the battery module of Modified Example 1.

[0018] Figure 4 is a cross-sectional view of a portion of an output terminal and a bus bar included in the battery module of Embodiment 2. DETAILED DESCRIPTION

[0019] Hereinafter, the present disclosure will be described based on preferred embodiments with reference to the accompanying drawings. The embodiments do not limit the present disclosure but are illustrative, and not all features described in the embodiments and combinations thereof are essential to the present disclosure. Identical or equivalent constitutional elements, members, and processes shown in each drawing are denoted by the same reference numerals, and redundant description is appropriately omitted. In addition, the scale and shape of each part shown in each drawing are conveniently set in order to facilitate the description, and are not limited unless specifically mentioned. In addition, in the present specification or claims, in the case where the terms "first", "second", and the like are used, the terms do not indicate any order or importance unless specifically mentioned, but are used as terms for distinguishing certain constitutional elements from other constitutional elements. In addition, in each drawing, a part of unimportant members is omitted from the basis of the description of the embodiments.

[0020] (Embodiment 1)

[0021] Figure 1FIG. 1 is a perspective view of a battery module 1 according to the embodiment 1. The battery module 1 includes a battery stack 2 and a bus bar 4. The battery stack 2 has a plurality of batteries 6 arranged. Each battery 6 is, for example, a primary battery such as a lithium primary battery, a lithium-ion battery, a nickel-hydrogen battery, a nickel-cadmium battery, or a secondary battery which is chargeable. Each battery 6 is a so-called square battery having a flat cuboid shape. An outer can 8 is provided with an opening of a substantially rectangular shape, and an electrode body, an electrolyte, and the like are housed in the outer can 8 through the opening. A substantially rectangular sealing plate 10 that closes the opening is fitted to the outer can 8.

[0022] A pair of output terminals 12 is provided on the sealing plate 10. Specifically, a positive terminal 12a is provided at one end in the length direction, and a negative terminal 12b is provided at the other end. Hereinafter, the positive terminal 12a and the negative terminal 12b will be collectively referred to as the output terminal 12 in a case where it is not necessary to distinguish the polarity of the pair of output terminals 12.

[0023] The outer can 8, the sealing plate 10, and the output terminal 12 are conductive bodies, for example, composed of a metal such as aluminum, iron, or stainless steel. The outer can 8 and the sealing plate 10 are joined, for example, by laser welding. Each output terminal 12 is inserted through a through-hole formed in the sealing plate 10. An insulating sealing member is present between each output terminal 12 and each through-hole. The outer can 8 can also be covered with an insulating film such as a shrink tube, not shown. In addition, the outer can 8 and the sealing plate 10 can be composed of an insulating resin.

[0024] Each battery 6 has a valve portion 14 on the sealing plate 10. The valve portion 14 is provided between the pair of output terminals 12 of the sealing plate 10. The valve portion 14 is also referred to as a safety valve, and is configured to open when the internal pressure of the battery 6 rises above a predetermined value, and to be able to release gas inside the battery 6. The valve portion 14 is composed of a thin-walled portion that is thinner than other portions provided to a part of the sealing plate 10, and a linear groove formed in the surface of the thin-walled portion. In this configuration, if the internal pressure of the battery 6 rises, the thin-walled portion is broken from the groove as a starting point, and thus the valve portion 14 opens.

[0025] The plurality of batteries 6 are arranged at a predetermined interval such that the main surfaces of the adjacent batteries 6 face each other. In the present embodiment, the batteries 6 are arranged in the horizontal direction. Hereinafter, the direction in which the batteries 6 are arranged is appropriately set as a first direction X, a horizontal direction intersecting the first direction X is set as a second direction Y, and a vertical direction intersecting the first direction X and the second direction Y is set as a third direction Z. In the present embodiment, the first direction X, the second direction Y, and the third direction Z are orthogonal to each other.

[0026] Each battery 6 is configured so that the output terminal 12 faces in the same direction. Each battery 6 of the present embodiment is configured so that the output terminal 12 faces upward in the vertical direction. In addition, each battery 6 is arranged in such a manner that, in the case where adjacent batteries 6 are connected in series, the positive terminal 12a of one battery 6 is adjacent to the negative terminal 12b of the other battery 6. In addition, in the case where adjacent batteries 6 are connected in parallel, the positive terminal 12a of one battery 6 is arranged adjacent to the positive terminal 12a of the other battery 6.

[0027] An unillustrated separator is arranged between adjacent two batteries 6. Thereby, the two batteries 6 are electrically insulated from each other. The separator is also called an insulating spacer, and is composed of, for example, a resin sheet having insulating properties. As the resin constituting the separator, resins such as polypropylene (PP), polybutylene terephthalate (PBT), polycarbonate (PC), Noryl (registered trademark) resin (modified PPE), and the like can be exemplified.

[0028] The plurality of batteries 6 is sandwiched by an unillustrated pair of end plates in the first direction X. The pair of end plates is adjacent to the batteries 6 located at both ends in the first direction X with the separators interposed therebetween. Each end plate is a metal plate composed of a metal such as iron, stainless steel, aluminum, or the like. In addition, the plurality of batteries 6 is restrained by an unillustrated pair of restraint members in the first direction X. The pair of restraint members is also called a connection bar, and is a long strip-shaped member long in the first direction X. The pair of restraint members is arranged, for example, in the second direction Y. Each restraint member is composed of a metal such as iron, stainless steel, or the like, for example.

[0029] The plurality of batteries 6 is sandwiched by the pair of end plates in the first direction X in a state where the plurality of separators is alternately arranged. The pair of restraint members is arranged in such a manner as to sandwich the plurality of batteries 6, the plurality of separators, and the pair of end plates in the second direction Y, and both ends of each restraint member are fixed to the pair of end plates. For example, the restraint member has a bent portion overlapping the main surface of the end plate at both ends in the first direction X, and the bent portion is fixed to the end plate by screw fastening or the like. The separator, the end plate, and the restraint member have a publicly known structure, and thus the illustration and detailed description thereof are omitted.

[0030] The output terminals 12 of adjacent batteries 6 are electrically connected to each other by a bus bar 4. The bus bar 4 is a substantially band-shaped metal member. One end portion of the bus bar 4 is connected to the positive terminal 12a of one of the two adjacent batteries 6, and the other end portion is connected to the negative terminal 12b of the other battery 6. In addition, the bus bar 4 can also connect the output terminals 12 of the same polarity of the plurality of adjacent batteries 6 in parallel to each other to form a battery block, and further connect the battery blocks in series to each other.

[0031] A pipe plate, not shown, is placed on the upper surface of the battery stack 2. The pipe plate has gas pipes that communicate the valve portions 14 of the respective batteries 6. Gases spouted from the respective batteries 6 flow into the gas pipes. In addition, the pipe plate has openings at positions overlapping the output terminals 12 of the respective batteries 6, and the bus bars 4 are placed at the respective openings. The plurality of bus bars 4 are supported by the pipe plate. Thus, the pipe plate also functions as a so-called bus bar plate. In addition, a voltage detection line is placed on the pipe plate.

[0032] Figure 2 Fig. 7 is a sectional view of a portion of the output terminal 12 and the bus bar 4 included in the battery module 1 according to Embodiment 1. The output terminal 12 has a bonding surface 16 and a probe trace 18 on a surface opposite to the bus bar 4. The bonding surface 16 is a surface at which the output terminal 12 is bonded to the bus bar 4. The bus bar 4 is bonded to the output terminal 12 in abutment with the bonding surface 16, for example, by laser welding. Specifically, the bus bar 4 is bonded to the bonding surface 16 by irradiating laser light L to a position at which the bonding surface 16 overlaps the bus bar 4. In addition, the output terminal 12 and the bus bar 4 can also be bonded by ultrasonic welding, electric arc welding, or the like.

[0033] The output terminal 12 and the bus bar 4 can each be composed of a single metal material or can be composed of clad materials. In addition, the output terminal 12 and the bus bar 4 can be the same kind of metal or can be different kinds of metal.

[0034] The probe trace 18 is a concave-convex formed by pressing a probe of a device that performs charge and discharge and inspection of the battery 6 against the output terminal 12. The shape of the probe trace 18 is not limited and can be conical, polyhedral conical, spherical, flat, crown, or the like. The probe trace 18 has a plurality of convex portions 20 that protrude toward the bus bar 4 more than the bonding surface 16. The height of the convex portion 20 is 50 μm or more and 200 μm or less. The height of the convex portion 20 is a distance in a stacking direction of the output terminal 12 and the bus bar 4 from the bonding surface 16 to an apex of the convex portion 20.

[0035] The bus bar 4 has a concave portion 22 opposite to the probe trace 18. The concave portion 22 is disposed to overlap the probe trace 18 as viewed in a stacking direction of the output terminal 12 and the bus bar 4. The depth of the concave portion 22 is equal to or more than the height of the convex portion 20. The depth of the concave portion 22 is a distance in the stacking direction of the output terminal 12 and the bus bar 4 from a surface abutting the bonding surface 16 to a bottom surface of the concave portion 22. The bus bar 4 according to the present embodiment has one concave portion 22 that overlaps the probe trace 18 as a whole.

[0036] If the bus bar 4 is placed on the joint surface 16 of the output terminal 12, the protrusions 20 of the probe marks 18 are received in the recesses 22. Ideally, all the protrusions 20 are received in the recesses 22. Thus, it is possible to suppress a case where the protrusions 20 interfere with the bus bar 4 and the bus bar 4 is lifted from the joint surface 16. As a result, since the joint surface 16 is closely adhered to the bus bar 4, it is possible to more reliably join the output terminal 12 and the bus bar 4.

[0037] As described above, the battery module 1 of the present embodiment includes: the battery stack 2 in which a plurality of batteries 6 each having an output terminal 12 are arranged; and the bus bar 4 that is joined to the output terminal 12 of each battery 6 and electrically connects the plurality of batteries 6. The output terminal 12 has the probe marks 18 on a surface opposite to the bus bar 4, and the bus bar 4 has the recesses 22 opposite to the probe marks 18. By providing the recesses 22 in the bus bar 4, it is possible to suppress a case where the probe marks 18 interfere with the bus bar 4 when the bus bar 4 is placed on the output terminal 12.

[0038] Thus, it is possible to improve the connection reliability of the output terminal 12 and the bus bar 4. Therefore, it is possible to improve the safety of the battery module 1. In addition, in a case where the position where the probe contacts the output terminal 12 is changed, it is possible to simply suppress the interference of the probe marks 18 and the bus bar 4 by changing the position of the recesses 22 of the bus bar 4 only in correspondence with the position of the probe marks 18.

[0039] In addition, the bus bar 4 of the present embodiment has one recess 22 that overlaps the probe marks 18 as a whole. Thus, compared to a case where a plurality of recesses 22 are provided, it is possible to simplify the shape of the bus bar 4. In addition, it is possible to suppress the complication of the manufacturing process and the rise in cost of the bus bar 4 due to the provision of the recesses 22.

[0040] The battery module 1 of Embodiment 1 can be modified as follows. Figure 3 is a cross-sectional view of a part of the output terminal 12 and the bus bar 4 included in the battery module 1 of Modification 1.

[0041] The bus bar 4 of the present modification has a plurality of recesses 22. The plurality of recesses 22 overlap different parts of the probe marks 18, respectively. One or a plurality of protrusions 20 are received in each recess 22. According to such a configuration, it is also possible to suppress a case where the probe marks 18 interfere with the bus bar 4 when the output terminal 12 is placed on the bus bar 4. Therefore, it is possible to improve the connection reliability of the output terminal 12 and the bus bar 4.

[0042] In addition, since it is possible to increase the thick wall portion of the bus bar 4, it is possible to improve the strength of the bus bar 4, as compared with the case where one recess 22 covering the entire probe mark 18 is provided. Further, it is also possible to irradiate the laser L also to the region of the bus bar 4 in which a plurality of recesses 22 are arranged. In this case, the region between the adjacent recesses 22 in the bus bar 4 is also joined with the output terminal 12. Therefore, this region also becomes the joint surface 16. Thus, it is possible to reduce the electrical resistance between the output terminal 12 and the bus bar 4.

[0043] (Embodiment 2)

[0044] Embodiment 2 has a configuration common to Embodiment 1, except for the structure of the bus bar 4 and the output terminal 12. Hereinafter, this embodiment will be described focusing on the different configuration from Embodiment 1, and the common configuration will be simply described or omitted. Figure 4 Fig. 10 is a cross-sectional view of a portion of the output terminal 12 and the bus bar 4 included in the battery module 1 of Embodiment 2.

[0045] The battery module 1 of this embodiment includes: the battery stack 2 in which a plurality of batteries 6 each having an output terminal 12 are arranged; and the bus bar 4 that is joined with the output terminal 12 of each battery 6 to electrically connect the plurality of batteries 6.

[0046] The output terminal 12 of this embodiment has a joint surface 16, a recess 22, and a probe mark 18. The joint surface 16 is a surface for joining the bus bar 4. The recess 22 is recessed in a direction away from the bus bar 4, as compared with the joint surface 16. The probe mark 18 is disposed inside the recess 22. The probe mark 18 has a plurality of protrusions 20 protruding from the bottom surface of the recess 22 toward the bus bar 4 side. The height of the protrusion 20 is 50 μm or more and 200 μm or less. The depth of the recess 22 is the height of the protrusion 20 or more. The depth of the recess 22 is the distance in the stacking direction of the output terminal 12 and the bus bar 4, from the joint surface 16 to the bottom surface of the recess 22. The height of the protrusion 20 is the distance in the stacking direction, from the bottom surface of the recess 22 to the apex of the protrusion 20.

[0047] As such, by providing the recess 22 in the region where the probe mark 18 is formed at the output terminal 12, it is also possible to suppress the case where the probe mark 18 interferes with the bus bar 4 when the bus bar 4 is placed on the output terminal 12. Thus, it is possible to improve the connection reliability of the output terminal 12 and the bus bar 4.

[0048] The above describes the embodiments of the present disclosure in detail. The above-described embodiments are merely ways of illustrating specific examples in implementing the present disclosure. The contents of the embodiments are not intended to limit the technical scope of the present disclosure, and various design changes such as changes, additions, and deletions of constituent elements can be made within the scope of the idea of the present disclosure defined by the claims. The new embodiments to which the design changes are applied have the effects of the embodiments and variations combined. In the above-described embodiments, the contents that can be subjected to such design changes are emphasized by being marked with "the present embodiment", "in the present embodiment", and the like, but design changes are also allowed for the contents that are not marked. Any combination of the above-described constituent elements is also effective as a mode of the present disclosure. The hatching on the cross sections of the drawings does not limit the material of the object to which the hatching is applied.

[0049] The number of the batteries 6 included in the battery module 1 is not particularly limited. The structure of each portion of the battery stack 2 including the constraint structure and the like of the plurality of batteries 6 is not particularly limited. The battery 6 can also be a cylindrical shape or the like.

[0050] [Industrial applicability]

[0051] The present application can be used for a battery module.

[0052] [Explanation of reference signs]

[0053] 1 battery module, 2 battery stack, 4 bus bar, 6 battery, 12 output terminal, 16 bonding surface, 18 probe mark, 20 protruding portion, 22 recessed portion.

Claims

1. A battery module comprising: a battery stack in which a plurality of batteries each having an output terminal are arranged, and a bus bar electrically connecting the plurality of batteries by engaging with the output terminal of each battery; the output terminal has a probe mark on a surface opposite to the bus bar; the bus bar has a recess opposite to the probe mark and overlapping the entirety of the probe mark, the recess is configured to suppress interference between the probe mark and the bus bar when the bus bar is placed on the output terminal.

2. A battery module comprising: a battery stack in which a plurality of batteries each having an output terminal are arranged, and a bus bar electrically connecting the plurality of batteries by engaging with the output terminal of each battery; the output terminal has a probe mark on a surface opposite to the bus bar; the bus bar has a plurality of recesses opposite to the probe mark and overlapping different portions of the probe mark, respectively, the recesses are configured to suppress interference between the probe mark and the bus bar when the bus bar is placed on the output terminal.

3. The battery module according to claim 1 or 2, the probe mark has a protrusion protruding toward the bus bar side than an engagement surface of the output terminal for engagement with the bus bar; the height of the protrusion is 50 μm or more and 200 μm or less.

4. A battery module, comprising: a battery stack in which a plurality of batteries each having an output terminal are arranged, and a bus bar electrically connecting the plurality of batteries by engaging with the output terminal of each battery; the output terminal has an engagement surface with the bus bar, a recess recessed in a direction away from the bus bar than the engagement surface, and a probe mark disposed in the recess.

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