Power storage device

Abstract

A power storage device (1) is provided with: power storage elements (100) having electrode terminals (120) disposed in a Z-axis plus direction; and a bus bar (70) joined to the electrode terminals (120). The bus bar (70) has: a bus bar body part (71) having joint sections (71a) joined to the electrode terminals (120); a first wall part (72); and a second wall part (73). The first wall part (72) is erected in the Z-axis plus direction from the bus bar body part (71). When viewed from the Z-axis plus direction, the second wall part (73) is disposed in such an orientation that the second wall part at least partially overlaps with the bus bar body part (71) and opposes the bus bar body part (71).

Description

[Technical field]

[0001] The present invention relates to an energy storage device including an energy storage element. [Background technology]

[0002] Patent Document 1 discloses a battery pack comprising multiple unit cells. In this battery pack, metal lines are joined to the electrode terminals of adjacent unit cells, thereby connecting the unit cells in series or parallel. Ultrasonic welding is used to join the metal lines to the electrode terminals of the unit cells. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-222675 A Summary of the Invention [Problem to be solved by the invention]

[0004] When ultrasonic welding is used to join the electrode terminals of the cells (energy storage elements) and the metal lines (bus bars) as in the above-mentioned conventional assembled battery (energy storage device), the pressure applied during the joining may cause distortion of the bus bars. Therefore, laser welding, which can join objects to be joined without contact, may be adopted to join the bus bars and the electrode terminals. Laser welding has the advantages of less welding distortion and relatively easy welding between different materials. However, during laser welding, spatter, which is molten metal powder, may scatter, and the scattered spatter may cause problems such as damage to the resin members of the energy storage device. It is possible to place a three-dimensional structure near the bus bars to prevent the spatter from scattering, but this may complicate the configuration of the energy storage device, for example.

[0005] The present invention was made by the present inventors by focusing on the above-mentioned problem, and has an object to provide a power storage device with improved quality and a simple configuration. [Means for solving the problem]

[0006] An energy storage device according to one embodiment of the present invention includes an energy storage element having electrode terminals arranged in a first direction, and a busbar joined to the electrode terminal, wherein the busbar has a busbar main body having a joint joined to the electrode terminal, a first wall portion erected in the first direction from the busbar main body, and a second wall portion at least partially overlapping with the busbar main body when viewed from the first direction and arranged in an orientation facing the busbar main body. Effect of the Invention

[0007] According to the present invention, it is possible to provide a power storage device with improved quality and a simple configuration. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view showing the appearance of a power storage device according to an embodiment. [Diagram 2] FIG. 2 is an exploded perspective view of the electricity storage device according to the embodiment. [Diagram 3] FIG. 3 is a perspective view showing the structural relationship between the bus bar frame, the bus bar, and the electrical device according to the embodiment. [Figure 4] FIG. 4 is a perspective view showing a state in which the energy storage element and an electric device according to the embodiment are connected via a bus bar. [Diagram 5] FIG. 5 is an exploded perspective view corresponding to FIG. [Figure 6] FIG. 6 is a partial enlarged view showing a method of joining a bus bar and an electrode terminal of an energy storage element according to an embodiment. [Figure 7] FIG. 7 is a partial enlarged view showing a bus bar and its surrounding configuration according to the first modification of the embodiment. [Figure 8] FIG. 8 is a partial enlarged view showing a bus bar and its surrounding structure according to the second modification of the embodiment. [Figure 9] FIG. 9 is a perspective view showing an appearance of a bus bar according to the third modification of the embodiment. [Figure 10] FIG. 10 is an exploded perspective view showing a connection relationship between a bus bar according to a third modification of the embodiment and an energy storage element and an electric device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] An energy storage device according to one embodiment of the present invention includes an energy storage element having electrode terminals arranged in a first direction, and a busbar joined to the electrode terminal, wherein the busbar has a busbar main body having a joint joined to the electrode terminal, a first wall portion erected in the first direction from the busbar main body, and a second wall portion at least partially overlapping with the busbar main body when viewed from the first direction and arranged in an orientation facing the busbar main body.

[0010] According to this configuration, the first wall portion functions as a wall that suppresses scattering of spatter generated when the busbar body portion and the electrode terminal are joined. This suppresses the occurrence of defects such as damage to other members due to scattering of spatter. The second wall portion is disposed, for example, directly above the busbar body portion, and can be used as a terminal for connecting to an electric device such as a relay or a control circuit. This provides the effect of suppressing the path resistance between the electrode terminal and the electric device, or reducing the size of the electric storage device. In this way, the electric storage device according to this aspect is an electric storage device with improved quality and a simple configuration.

[0011] The second wall portion may have an opening penetrating in the first direction, and positioned so that at least a portion of the opening overlaps with the joint portion when viewed from the first direction.

[0012] According to this configuration, for example, the busbar body and the electrode terminal can be joined by irradiating the laser light through the opening from a position facing the busbar body. In other words, the busbar body can be efficiently irradiated with the laser light through the opening in the second wall, and the scattering of spatter can be suppressed in the portion other than the opening in the second wall. This makes it possible to efficiently form a highly reliable joint.

[0013] The second wall portion may be provided upright from an end portion of the first wall portion opposite to the busbar main body portion in a direction intersecting the first wall portion.

[0014] This configuration realizes a busbar in which the busbar body, the first wall, and the second wall are connected in this order, thereby achieving effects such as a reduction in the spatial volume required for arranging the busbar and a further suppression of the path resistance between the electrode terminal and the electrical device.

[0015] The energy storage device may further include an insulating member disposed between the busbar main body and the second wall portion.

[0016] According to this configuration, in a busbar having a wall (first wall) rising from the busbar main body and therefore susceptible to external forces during a collision or the like, an insulating member is provided between the busbar main body and the second wall. As a result, if the first wall is deformed by a large external force, for example, the insulating member functions as a member that suppresses contact between a part of the busbar and other conductive members. This reduces the possibility of a short circuit occurring during a collision or the like.

[0017] The busbar main body may have a protrusion that protrudes in a second direction intersecting the first direction, and is provided at a position that does not overlap with the second wall portion when viewed from the first direction.

[0018] According to this configuration, for example, in a structure in which the second wall portion is located directly above the busbar body, the busbar body has a protruding portion that protrudes laterally, and the protruding portion can be used as a pressing portion that presses the busbar body when performing a joining operation by laser welding, etc. This results in a highly reliable joint.

[0019] The busbar main body may be joined to the electrode terminals of each of the two energy storage elements arranged side by side.

[0020] According to this configuration, the bus bar functions as a conductive member for connecting to an electric device such as a relay or a control circuit, and also functions as a conductive member for connecting at least two adjacently arranged power storage elements in series or parallel, which contributes to suppressing the path resistance or reducing the size of the power storage device, thereby improving the quality of the power storage device.

[0021] Hereinafter, a description will be given of an energy storage device according to an embodiment (including its modified examples) of the present invention with reference to the drawings. The embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, the arrangement and connection of the components, manufacturing processes, and the order of the manufacturing processes shown in the following embodiments are merely examples and are not intended to limit the present invention. In each drawing, the dimensions are not strictly shown. Furthermore, in each drawing, the same or similar components are given the same symbols.

[0022] In the following description and drawings, the longitudinal direction of the exterior body of the energy storage device, the arrangement direction of the multiple energy storage elements, or the opposing direction of the long side surfaces of the containers of the energy storage elements is defined as the X-axis direction. The transverse direction of the exterior body of the energy storage device, the opposing direction of the short side surfaces of the containers of the energy storage elements, or the arrangement direction of a pair of electrode terminals in one energy storage element is defined as the Y-axis direction. The arrangement direction of the main body and the lid of the exterior body of the energy storage device, the arrangement direction of the bus bar frame and the energy storage element unit, or the up-down direction is defined as the Z-axis direction. The X-axis direction, the Y-axis direction, and the Z-axis direction intersect with each other (orthogonal in this embodiment). Depending on the mode of use, the Z-axis direction may not be the up-down direction, but for convenience of explanation, the following description will be given assuming that the Z-axis direction is the up-down direction.

[0023] In the following description, for example, the positive X-axis direction refers to the direction of the X-axis arrow, and the negative X-axis direction refers to the opposite direction to the positive X-axis direction. The same applies to the Y-axis and Z-axis directions. When simply referring to the "X-axis direction," it means either or both directions parallel to the X-axis. The same applies to terms related to the Y-axis and Z-axis.

[0024] Furthermore, expressions indicating a relative direction or attitude, such as "parallel" and "orthogonal," also include cases where the direction or attitude is not strictly the same. For example, "two directions are orthogonal" does not only mean that the two directions are completely orthogonal, but also means that the two directions are substantially orthogonal, that is, includes a difference of, for example, about several percent.

[0025] (Embodiment) [1. General description of the power storage device] First, a schematic configuration of an energy storage device 1 according to an embodiment will be described. Fig. 1 is a perspective view showing the appearance of the energy storage device 1 according to an embodiment. Fig. 2 is an exploded perspective view of the energy storage device 1 according to an embodiment. Fig. 3 is a perspective view showing the structural relationship of a bus bar frame 30, bus bars 60 and 70, and an electric device 40 according to an embodiment. Fig. 3 illustrates a state in which the bus bars 60 and 70 and the electric device 40 are separated from the bus bar frame 30. Fig. 3 illustrates members such as the bus bar frame 30 rotated 180° around the Z axis from the attitude illustrated in Fig. 2.

[0026] 2 and subsequent figures, a bus bar that connects the electric device 40 and the external terminal 13 is housed inside the exterior body 10, and further, spacers that are arranged along the energy storage elements 100, restraining members that restrain the multiple energy storage elements 100, and the like may be arranged inside the exterior body 10. However, illustrations and descriptions of these members will be omitted as appropriate.

[0027] The power storage device 1 is a device that can charge electricity from the outside and discharge electricity to the outside, and has a substantially rectangular parallelepiped shape in this embodiment. The power storage device 1 is, for example, a battery module (battery pack) used for power storage or power source. Specifically, the power storage device 1 is used as a battery for driving or starting an engine of a moving body such as an automobile, a motorcycle, a watercraft, a ship, a snowmobile, an agricultural machine, a construction machine, or a railway vehicle for an electric railway. Examples of the automobile include an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), and a gasoline vehicle. Examples of the railway vehicle for the electric railway include a train, a monorail, a linear motor car, and a hybrid train equipped with both a diesel engine and an electric motor. The power storage device 1 can also be used as a stationary battery for home use or for a power generator.

[0028] 1 and 2, the energy storage device 1 includes an exterior body 10, and an energy storage element unit 50 and a bus bar frame 30 housed in the exterior body 10. The exterior body 10 is a box-shaped (approximately rectangular parallelepiped) container (module case) that constitutes the housing of the energy storage device 1. In other words, the exterior body 10 is disposed outside the energy storage element unit 50 and the bus bar frame 30, fixes the energy storage element unit 50 and the bus bar frame 30 at predetermined positions, and protects them from impacts and the like. The exterior body 10 is formed of an insulating material such as polycarbonate (PC), polypropylene (PP), polyethylene (PE), polystyrene (PS), polyphenylene sulfide resin (PPS), polyphenylene ether (PPE (including modified PPE)), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyether ether ketone (PEEK), tetrafluoroethylene perfluoroalkyl vinyl ether (PFA), polytetrafluoroethylene (PTFE), polyether sulfone (PES), ABS resin, or a composite material thereof, or a metal or the like with an insulating coating. This prevents the energy storage element unit 50 and the like from coming into contact with external metal members and the like. As long as the electrical insulation between the exterior body 10 and the energy storage element unit 50 and the like is maintained, the exterior body 10 may be formed of a conductive material such as a metal.

[0029] The exterior body 10 has an exterior body main body 12 that constitutes the main body of the exterior body 10, and a lid body 11. The exterior body main body 12 is a bottomed rectangular tubular housing having an opening 12a formed on the positive side of the Z axis, and houses the energy storage element unit 50, the bus bar frame 30, and the like.

[0030] The lid 11 is a rectangular member that closes the opening 12a of the exterior body 12. The lid 11 is joined to the exterior body 12, preferably in an airtight or watertight manner, by adhesive, heat sealing, ultrasonic welding, laser welding, or the like. A pair of external terminals 13, which are a pair of module terminals on the positive and negative sides, are arranged on the lid 11. The energy storage device 1 charges with electricity from the outside and discharges electricity to the outside via the pair of external terminals 13. The external terminals 13 are formed of a conductive member made of metal, such as aluminum, an aluminum alloy, copper, or a copper alloy.

[0031] The energy storage element unit 50 is an assembly of one or more energy storage elements 100. The energy storage element unit 50 according to this embodiment is composed of a plurality of energy storage elements 100, and the plurality of energy storage elements 100 are arranged in the X-axis direction with their respective long side surfaces 110a facing the X-axis direction. The energy storage element unit 50 may have spacers (not shown) disposed between adjacent energy storage elements 100, and may have restraining members (not shown) that restrain the plurality of energy storage elements 100.

[0032] The energy storage element 100 is a secondary battery (single cell) capable of charging and discharging electricity, and more specifically, a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery. As shown in FIG. 2, the energy storage element 100 has a flat rectangular parallelepiped (rectangular) container 110 and a pair of electrode terminals 120 (positive and negative) fixed to the container 110. An electrode body, a current collector, an electrolyte, and the like (not shown) are accommodated inside the container 110. An example of the electrode body of the energy storage element 100 is a wound type electrode body formed by winding a layered arrangement in which a separator is sandwiched between a positive electrode plate and a negative electrode plate. In addition, the energy storage element 100 may be provided with a stack type electrode body formed by stacking a plurality of flat electrode plates, or a bellows type electrode body in which an electrode plate is folded in a bellows shape.

[0033] The energy storage element 100 is not limited to a nonaqueous electrolyte secondary battery, and may be a secondary battery other than a nonaqueous electrolyte secondary battery, or may be a capacitor. The energy storage element 100 may not be a secondary battery, but may be a primary battery that can use stored electricity without the user having to charge it. The energy storage element 100 may be a battery using a solid electrolyte. The energy storage element 100 may be a pouch-type energy storage element. The shape of the energy storage element 100 is not limited to the above-mentioned square shape, and may be other shapes such as a polygonal column shape, a cylindrical shape, an elliptical column shape, or an oblong column shape.

[0034] In this embodiment, the container 110 has a pair of long side surfaces 110a, a pair of short side surfaces 110b, and a terminal arrangement surface 110c, as shown in Fig. 2. The terminal arrangement surface 110c is a surface on which the positive and negative electrode terminals 120 are arranged. In this embodiment, a gas exhaust valve 105 is further arranged on the terminal arrangement surface 110c. The gas exhaust valve 105 is a part that opens in response to an excessive internal pressure of the container 110, thereby discharging gas inside the container 110 to the outside.

[0035] The bus bar frame 30 is disposed opposite the terminal arrangement surface 110c of the energy storage element 100, and is a flat rectangular insulating member that holds the bus bars 60 and 70 and the electric device 40. The bus bar frame 30 is formed of, for example, any electrically insulating resin material that can be used for the exterior body 10 described above.

[0036] As shown in FIG. 3, the bus bar frame 30 has a plurality of bus bar openings 30a that hold the bus bars 60 and 70 in a state in which a portion of each of the bus bars 60 and 70 is exposed to the energy storage element 100 side. Each of the bus bars 60 and 70 arranged in the bus bar openings 30a is positioned with respect to the electrode terminal 120 to be joined, and in this state, is joined to the electrode terminal 120 by, for example, laser welding. In this embodiment, the energy storage element unit 50 has eight energy storage elements 100. Of these eight energy storage elements 100, two adjacent energy storage elements 100 are connected in parallel by a bus bar 60, thereby forming four groups of energy storage elements 100 connected in parallel. Furthermore, these four groups of energy storage elements 100 are connected in series by three bus bars 60. A bus bar 70 is joined to each of the total positive terminal 121 and the total negative terminal 122 of the energy storage element unit 50 having the eight energy storage elements 100 electrically connected in this manner. In this embodiment, as shown in FIG. 2, the positive electrode terminals 120 of the two storage elements 100 at the ends in the positive direction of the X-axis are total positive terminals 121, and the negative electrode terminals 120 of the two storage elements 100 at the ends in the negative direction of the X-axis are total negative terminals 122.

[0037] The electric device 40 arranged on the bus bar frame 30 is electrically connected to the energy storage element unit 50 via the bus bar 70. In the present embodiment, as shown in Fig. 2, the electric device 41 and 42 are provided in the energy storage device 1 as the electric device 40 arranged on the bus bar frame 30.

[0038] The electric device 42 is, for example, a control device called a BMU (Battery Management unit), which detects the voltage of each of the multiple energy storage elements 100 and the temperature of the energy storage element unit 50, and controls the charging state of the multiple energy storage elements 100. A connection terminal 42a of the electric device 42 is connected to a bus bar 70 with a screw 48, whereby the electric device 42 and the two electrode terminals 120, which are the total negative terminal 122, are electrically and mechanically connected by the bus bar 70. The electric device 42 is electrically connected to a negative external terminal 13 fixed to the cover 11 of the exterior body 10 via a bus bar (not shown).

[0039] The electric device 41 is, for example, a relay unit having an electromagnetic switch, and has a function of switching on and off the charging or discharging of the electricity storage device 1. The connection terminal 41a of the electric device 41 is connected to the bus bar 70 with a screw 48, whereby the electric device 41 and the two electrode terminals 120, which are the total positive terminals 121, are electrically and mechanically connected by the bus bar 70. The electric device 41 is electrically connected to the positive electrode side external terminal 13 fixed to the lid 11 of the exterior body 10 via a bus bar (not shown).

[0040] In the energy storage device 1 configured in this manner, the busbar 70 connecting the electric device 40 and the energy storage element unit 50 has a busbar main body 71, a first wall 72, and a second wall 73 that are arranged three-dimensionally, as shown in Fig. 3. The busbar 70 having such a characteristic shape and its surrounding configuration will be described below.

[0041] [2. Busbar and its surrounding structure] Next, the busbar 70 and its surrounding configuration in the energy storage device 1 will be described with reference to Fig. 4 to Fig. 6. In this embodiment, two busbars 70 are provided to connect the energy storage element unit 50 and the electric device 40, and these two busbars 70 have common features. Therefore, the following description will focus on the busbar 70 connected to the electric device 41, and illustrations and descriptions of the busbar 70 connected to the electric device 42 will be omitted.

[0042] Fig. 4 is a perspective view showing a state in which an energy storage element 100 and an electric device 41 according to the embodiment are connected via a bus bar 70. Fig. 4 illustrates only the bus bar 70 and two energy storage elements 100 and an electric device 41 connected to the bus bar 70, and does not illustrate other members such as the other energy storage elements 100 and the bus bar frame 30. Fig. 5 is an exploded perspective view corresponding to Fig. 4. Fig. 6 is a partial enlarged view showing a method of joining the bus bar 70 according to the embodiment to an electrode terminal 120 of the energy storage element 100.

[0043] As shown in Figs. 4 to 6, in an energy storage device 1 according to this embodiment, an energy storage element 100 has an electrode terminal 120 in the positive direction of the Z axis, which is an example of a first direction. The electrode terminal 120 and the busbar 70 are joined at a joint 71a formed in a busbar main body 71 of the busbar 70. In this embodiment, the joint 71a is formed by laser welding. In this embodiment, the busbar main body 71 is formed with a through hole through which a bolt passes so that it can also be joined to a bolt terminal, but the busbar main body 71 does not have to have a through hole for joining to a bolt terminal.

[0044] The busbar 70 further has a first wall portion 72 standing upright from the busbar main body 71 in the positive direction of the Z axis. That is, when viewed from the joint 71a, the first wall portion 72 exists as a metallic shielding wall that separates the space on the positive side of the Y axis. Therefore, even if spatter is generated during laser welding to form the joint 71a, at least the scattering of the spatter toward the positive side of the Y axis of the busbar 70 is suppressed. Since the laser welding is performed with the energy storage element unit 50 housed in the exterior body 12, the first wall portion 72 suppresses damage caused by spatter to the exterior body main body 12 and the portions of the busbar frame 30 located on the positive side of the busbar 70 in the Y axis direction.

[0045] Further, a second wall portion 73 is fixed to the first wall portion 72 in a position facing the busbar main body portion 71. A mounting hole 73a for connection to the electric device 41 is formed in the second wall portion 73, and a screw 48 inserted into the mounting hole 73a through a connection terminal 41a of the electric device 41 is screwed into a nut 49, thereby connecting the busbar 70 to the electric device 41. That is, the electric device 41 is connected to the electrode terminal 120 with a relatively short conduction path between the electrode terminal 120. An opening portion 74 is further formed in the second wall portion 73. As shown in FIG. 6, the opening portion 74 is used as a hole for passing laser light La in laser welding between the busbar main body portion 71 and the electrode terminal 120 of the energy storage element 100. That is, by providing the opening portion 74 in the second wall portion 73, the laser light La can be irradiated to the busbar main body portion 71 from a position opposite to the busbar main body portion 71 across the second wall portion 73.

[0046] Thus, the energy storage device 1 according to this embodiment includes energy storage elements 100 having electrode terminals 120 arranged in the positive direction of the Z axis, and a busbar 70 joined to the electrode terminals 120. The busbar 70 has a busbar main body 71 having a joint 71a joined to the electrode terminal 120, a first wall 72, and a second wall 73. The first wall 72 stands in the positive direction of the Z axis from the busbar main body 71. The second wall 73 is at least partially overlapping with the busbar main body 71 when viewed from the positive direction of the Z axis, and is disposed in a position facing the busbar main body 71.

[0047] According to this configuration, for example, the first wall portion 72 functions as a wall that suppresses scattering of spatters generated when the busbar main body portion 71 and the electrode terminal 120 are joined. This suppresses the occurrence of defects such as damage to other members such as the busbar frame 30 and the exterior body 12 due to scattering of spatters. The second wall portion 73 is disposed directly above the busbar main body portion 71 (on the Z-axis positive side) and can be used as a terminal to connect to the electric device 41. Therefore, effects such as suppression of the path resistance between the electrode terminal 120 and the electric device 41 and miniaturization of the energy storage device 1 can be obtained. In the present embodiment, the busbar 70 is a member that directly connects the energy storage element unit 50 and the electric device 40 (41, 42) in the main current path through which current flows when the energy storage element unit 50 is discharged and charged. Therefore, since the path resistance in the busbar 70 is relatively small, for example, the charge and discharge efficiency of the energy storage device 1 is improved. In this way, the energy storage device 1 according to this embodiment can improve its quality with a simple configuration.

[0048] In this embodiment, when viewed from the center of the energy storage element 100 in a top view, the first wall portion 72 is located outside the joint portion 71a (on the positive Y-axis direction side in FIGS. 4 to 6). However, the first wall portion 72 may be located inside the joint portion 71a (on the negative Y-axis direction side in FIGS. 4 to 6). However, it is advantageous for the first wall portion 72 to be located outside the joint portion 71a in terms of protecting the peripheral portion of the opening 12a of the exterior body main body 12 (see FIG. 2). Specifically, when the first wall portion 72 is located outside the joint portion 71a, the first wall portion 72 is disposed between the joint portion 71a and the part of the peripheral portion of the opening 12a that is closest to the joint portion 71a. This allows the first wall portion 72 to protect the peripheral portion of the opening 12a before it is joined to the lid body 11 from sputtering that occurs when the joint portion 71a is formed. This reduces the possibility that the peripheral portion of the opening 12a is deformed or damaged by sputtering. As a result, the lid 11 and the exterior body 12 can be joined with high precision by welding or the like.

[0049] In this embodiment, the second wall portion 73 has an opening 74 that penetrates in the positive direction of the Z axis and is arranged at a position where at least a portion of the opening 74 overlaps with the joint portion 71a when viewed from the positive direction of the Z axis. Specifically, as shown in Fig. 6, the joint portion 71a is formed inside a projection area (opening area 74a) of the opening of the opening 74 on the busbar main body portion 71. In other words, a portion of the opening 74 overlaps with the joint portion 71a when viewed from the positive direction of the Z axis.

[0050] According to this configuration, the busbar main body 71 and the electrode terminal 120 can be joined by irradiating the laser light through the opening 74 from a position facing the busbar main body 71. That is, the laser light can be irradiated to the busbar main body 71 in a direction parallel to its thickness direction (a direction perpendicular to the surface of the busbar main body 71). That is, the laser light can be efficiently irradiated to the busbar main body 71 through the opening 74 of the second wall 73. Furthermore, scattering of sputters can be suppressed in the portions of the second wall 73 other than the opening 74. This makes it possible to efficiently form a highly reliable joint 71a.

[0051] In this embodiment, the second wall portion 73 is erected in a direction intersecting with the first wall portion 72 from the end portion of the first wall portion 72 opposite the busbar main body portion 71 (the end portion in the positive direction of the Z axis).

[0052] This configuration realizes the busbar 70 in which the busbar main body 71, the first wall 72, and the second wall 73 are connected in this order. As a result, it is possible to obtain effects such as a reduction in the spatial volume required for arranging the busbar 70 and a further suppression of the path resistance between the electrode terminal 120 and the electric device 40.

[0053] In the present embodiment, busbar main body 71 is joined to electrode terminals 120 of two energy storage elements 100 arranged side by side, as shown in FIGS.

[0054] That is, in the present embodiment, the bus bar 70 functions as a conductive member for connecting to the electric device 40, and also functions as a conductive member for connecting at least two energy storage elements 100 arranged side by side in series or in parallel (parallel in the present embodiment). This contributes to suppressing the path resistance or reducing the size of the energy storage device 1, and as a result, the quality of the energy storage device 1 is improved.

[0055] Although the energy storage device 1 according to the embodiment has been described above, the energy storage device 1 may have a configuration of the bus bar 70 and its periphery that is different from the configuration shown in Figures 4 to 6. Therefore, below, modified examples of the bus bar 70 and its periphery will be described, focusing on the differences from the above embodiment.

[0056] (Variation 1) Fig. 7 is a partially enlarged view showing a bus bar 70 and its surrounding configuration according to the first modification of the embodiment. In Fig. 7, the illustration of the electric device 40 connected to the bus bar 70 is omitted, and the insulating member 80 is illustrated shifted in the negative Y-axis direction from its original position.

[0057] 7, in the energy storage device 1a according to the first modification, an insulating member 80 is attached to the bus bar 70, which is different from the energy storage device 1 according to the embodiment. Specifically, the energy storage device 1a includes an insulating member 80 disposed between the bus bar main body 71 and the second wall portion 73.

[0058] In this manner, in this modification, in busbar 70 having a structure that is susceptible to external forces during a collision or the like due to having a wall (first wall 72) rising from busbar main body 71, insulating member 80 is provided between busbar main body 71 and second wall 73. As a result, if first wall 72 is deformed by receiving a large external force, for example, insulating member 80 functions as a member that suppresses contact between part of busbar 70 and other conductive members such as container 110 of energy storage element 100. This reduces the possibility of a short circuit occurring during a collision or the like.

[0059] In this embodiment, the insulating member 80 has a nut holding portion 81 that holds the nut 49. When viewed from the axial direction (Z-axis direction) of the nut 49, the nut holding portion 81 is a non-circular recess that covers the outer periphery of the nut 49 having a non-circular outer shape, and therefore also functions as a rotation stopper for the nut 49. This allows the electrical device 40 to be easily and reliably attached to the bus bar 70 using the screw 48 and the nut 49. Furthermore, the outer periphery and the lower surface (the surface on the energy storage element 100 side (Z-axis negative direction side)) of the nut 49 are covered by the insulating member 80. Therefore, even if the nut 49 moves due to the deformation of the bus bar 70 during a collision or the like, the possibility that other members are damaged by the nut 49, which is a metal body, is reduced. In other words, the insulating member 80 according to this modification functions as a member for improving safety and also functions as a member for improving the manufacturing efficiency of the energy storage device 1a.

[0060] In this modification, when viewed from the center of the energy storage element 100 in a top view, the first wall portion 72 is disposed at the end portion on the outer side (the positive side in the Y-axis direction in FIG. 7 ) of the busbar main body 71. Therefore, as shown in FIG. 7 , the insulating member 80 can be easily disposed on the busbar 70 from the inside. In contrast, assuming that the first wall portion 72 is erected at the end portion on the inner side (the negative side in the Y-axis direction) of the busbar main body 71, it is difficult to dispose the insulating member 80 from the outside of the busbar 70. Specifically, since the peripheral portion (see FIG. 2 ) of the opening 12a of the exterior body 12 is present near the outside of the busbar 70, it is highly likely that the peripheral portion will interfere with the disposition of the insulating member 80. In other words, the first wall portion 72 is erected at the outer end portion of the busbar main body 71, from the viewpoint of ease of disposing the insulating member 80 between the busbar main body 71 and the second wall portion 73.

[0061] (Variation 2) Fig. 8 is a partial enlarged view showing a bus bar 70a and its surrounding configuration according to Modification 2 of the embodiment. In Fig. 8, illustration of electric device 40 connected to bus bar 70a is omitted.

[0062] As shown in FIG. 8, the busbar 70a included in the energy storage device 1b according to the second modification has a busbar main body 71 joined to the electrode terminal 120 of the energy storage element 100, a first wall 72 standing from the busbar main body 71 in the positive direction of the Z axis, and a second wall 73 disposed in a position facing the busbar main body 71. This configuration is common to the busbar 70a according to the present modification and the busbar 70 according to the embodiment. In the busbar 70a according to the present modification, the first wall 72 stands on an end of the busbar main body 71 in the negative direction of the X axis with the thickness direction facing the arrangement direction of the energy storage elements 100 (the X axis direction). Furthermore, the second wall 73 stands on an end of the first wall 72 in the positive direction of the Z axis in the positive direction of the X axis. In other words, the busbar 70 according to the embodiment is U-shaped as a whole when viewed from the X axis direction, whereas the busbar 70a according to the present modification is U-shaped as a whole when viewed from the Y axis direction. Even in this case, the first wall portion 72 functions as a wall that suppresses scattering of spatter generated when the busbar main body portion 71 and the electrode terminal 120 are joined. The second wall portion 73 can be connected to the electric device 40 at a position close to the busbar main body portion 71, so that the path resistance between the energy storage element 100 and the electric device 40 is relatively small. Furthermore, the second wall portion 73 has an opening portion 74, so that the busbar main body portion 71 can be efficiently irradiated with laser light through the opening portion 74.

[0063] Furthermore, in this modified example, the busbar main body 71 has a protrusion 77 that protrudes in a second direction (the Y-axis direction in this modified example) intersecting the positive Z-axis direction, and is provided at a position that does not overlap with the second wall portion 73 when viewed from the positive Z-axis direction.

[0064] In this manner, in a structure in which the second wall portion 73 is located directly above the busbar main body 71, the busbar main body 71 has the protrusion 77 protruding laterally, which allows the protrusion 77 to be used as a pressing portion for pressing the busbar main body 71 when performing a joining operation by laser welding or the like. This results in a highly reliable joint 71a. The protrusion 77 can also be used, for example, as an attachment portion for attaching an electric wire for voltage measurement. There is no particular limitation on the number and positions of the protrusions 77. For example, the busbar main body 71 may further have a protrusion 77 that is arranged at an end portion in the positive direction of the X-axis and protrudes in the positive direction of the X-axis.

[0065] (Variation 3) Fig. 9 is a perspective view showing the appearance of a busbar 170 according to the third modification of the embodiment. Fig. 10 is an exploded perspective view showing the connection relationship between the busbar 170 according to the third modification of the embodiment, the energy storage elements 100, and the electric device 41. In Fig. 10, with regard to the energy storage elements 100, only two energy storage elements 100 to which the busbar 170 is joined are illustrated, and the other energy storage elements 100 are omitted. In Fig. 10, the busbar 60 joined to the other energy storage elements 100 is illustrated by a dotted line, and other members such as a busbar frame are omitted.

[0066] 9 and 10, busbar 170 according to this modification has busbar main body 171 having joint portion 171a joined to electrode terminal 120, a first wall portion 172, and a second wall portion 173. First wall portion 172 stands upright from busbar main body 171 in the positive direction of the Z axis. Second wall portion 173 is at least partially overlapping busbar main body 171 when viewed from the positive direction of the Z axis, and is disposed in a position facing busbar main body 171. These configurations are in common with busbar 70 according to the embodiment.

[0067] Busbar 170 according to this modification differs from busbar 70 according to the embodiment in that it is formed by joining two busbars. Specifically, busbar 170 has first busbar 170a which forms busbar main body 171 and first wall portion 172, and second busbar 170b which forms second wall portion 173. First busbar 170a and second busbar 170b are joined by joining member 175 which is made up of a bolt and a nut (not shown).

[0068] In this way, even when the busbar 170 is composed of a plurality of members, the first wall portion 172 functions as a wall that suppresses scattering of spatters that occur when the busbar main body portion 171 and the electrode terminal 120 are joined. The second wall portion 173 is disposed directly above the busbar main body portion 171 (on the positive side of the Z axis), and can be used as a terminal to connect to the electric device 41. Therefore, effects such as suppression of the path resistance between the electrode terminal 120 and the electric device 41 and miniaturization of the power storage device 1 can be obtained. Specifically, in this modification, the second busbar 170b has a screw shaft portion 178 for connection to the electric device 41, and as shown in FIG. 10, the screw shaft portion 178 inserted into the connection terminal 41a of the electric device 41 is screwed into a nut 49, whereby the busbar 170 and the electric device 41 are connected. There is no particular limitation on the method for joining the second busbar 170b and the electric device 41. The second bus bar 170b and the electric device 41 may be joined by welding or crimping.

[0069] Furthermore, in this modification, similarly to the above modification 1, an insulating member 180 is disposed between the busbar main body 171 and the second wall 173. As a result, when the first wall 172 is deformed by receiving a large external force, for example, the insulating member 180 functions as a member that suppresses contact between the second busbar 170b and other conductive members such as the container 110 of the energy storage element 100. This reduces the possibility of a short circuit occurring during a collision or the like. As shown in FIG. 10, the insulating member 180 according to this modification is a busbar cover that collectively covers the busbar main body 171 and the busbar 60. That is, the insulating member 180 can protect not only the busbar main body 171 that is a part of the busbar 170, but also one or more busbars 60. In other words, the reliability of electrical insulation between the second busbar 170b and other conductive members such as the container 110 of the energy storage element 100 is improved by using a part of the busbar cover that protects the one or more busbars 60.

[0070] First wall portion 172 of busbar 170 may be formed by a part of second busbar 170b, not first busbar 170a. The position of first wall portion 172 does not have to be the end portion on the inner side (the Y-axis negative side in FIG. 10) of busbar main body portion 171. First wall portion 172 may be provided at the end portion on the outer side (the Y-axis positive side) of busbar main body portion 171. First wall portion 172 may be provided at one of both ends in the width direction (X-axis direction) of busbar main body portion 171. The joining method of first busbar 170a and second busbar 170b does not have to be fastening with bolts and nuts. For example, first busbar 170a and second busbar 170b may be joined by other joining methods such as welding or crimping. The number of separate busbars constituting busbar 170 is not limited to two. One busbar 170 may be constituted by connecting three or more busbars.

[0071] (Other embodiments) Although the energy storage device 1 according to the embodiment of the present invention has been described above, the present invention is not limited to this embodiment. In other words, the embodiment disclosed herein is illustrative and not restrictive in all respects, and the scope of the present invention includes all modifications within the meaning and scope equivalent to the claims.

[0072] For example, the busbar 70 and the electric device 40 do not have to be directly connected. For example, an electric wire connected to the electric device 42, which is a BMU, may be connected to a mounting hole 73a provided in the second wall portion 73 of the busbar 70 by a screw or the like. It is not essential that a member (electrically-conductive member) such as the electric device 40, which is assumed to be electrically-conductive, is connected to the second wall portion 73 of the busbar 70. For example, a non-electrically-conductive member such as the lid body 11 may be connected to the second wall portion 73 of the busbar 70 by engagement, fitting, adhesion, screw fastening, or the like. This allows the busbar 70 to function as a member supporting the non-electrically-conductive member. The first wall portion 72 may be used as a connection portion with the electrically-conductive member. For example, in a state in which the electrode terminal 120 is joined to the busbar main body portion 71 and the electric device 40 is attached to the second wall portion 73, an electrically-conductive member such as an electric wire for voltage measurement or a non-electrically-conductive member such as the lid body 11 may be further connected to the first wall portion 72. In this case, the first wall portion 72 may be provided with a hole, a notch, a protrusion, or the like for attaching a conductive member or a non-conductive member.

[0073] That is, the size of the busbar 70 according to this embodiment when viewed from above (when viewed from the positive direction of the Z axis) is approximately the same as that of the busbar main body 71, but has additional connection allowances (connectable areas) provided by the first wall 72 and the second wall 73. Therefore, the busbar 70 can electrically and mechanically connect multiple energy storage elements 100 in a relatively small space, and can also form conductive paths between the multiple energy storage elements 100 and the electric device 40, etc., and can support other components by mechanical connection, etc.

[0074] The number of energy storage elements 100 directly connected to the busbar main body 71 of the busbar 70 is not limited to two, and it is sufficient that the electrode terminals 120 of one or more energy storage elements 100 are joined to the busbar main body 71. For example, a busbar 60 (see FIG. 3) connecting four energy storage elements 100 may have a first wall portion standing in the positive direction of the Z axis and a second wall portion arranged in a position facing the busbar 60. In other words, the three-dimensional structure formed by a combination of three plate-like portions (the busbar main body, the first wall portion, and the second wall portion), which is a feature of the busbar 70, may be adopted for any busbar connected to any of the multiple energy storage elements 100. The application of the three-dimensional structure to the busbar may be determined as appropriate depending on the number, type, size, or arrangement position of the electric devices 40 included in the energy storage device 1, or the size or shape of the exterior body 10, etc.

[0075] Any combination of the components included in the above-described embodiment and its modified examples is also included within the scope of the present invention. [Industrial Applicability]

[0076] The present invention can be applied to an electricity storage device including an electricity storage element such as a lithium ion secondary battery. [Explanation of symbols]

[0077] 1, 1a, 1b Energy storage device 30 Busbar Frame 40, 41, 42 Electrical equipment 50 Energy storage element unit 60, 70, 70a, 170 busbars 71, 171 Busbar body 71a, 171a joint 72, 172 First wall part 73, 173 Second wall part 73a Mounting hole 74 Opening 74a opening area 77 Protrusion 80, 180 Insulating material 100 Energy storage element 120 Electrode terminal

Claims

1. an energy storage element having electrode terminals arranged in a first direction; a bus bar joined to the electrode terminal, The bus bar is a busbar main body having a joint portion joined to the electrode terminal by laser welding; a first wall portion extending in the first direction from the busbar main body; a second wall portion at least partially overlapping with the busbar main body portion when viewed from the first direction and disposed in a position facing the busbar main body portion, The second wall portion has an opening penetrating in the first direction, and the opening is arranged at a position at which at least a portion of the opening overlaps with the joint portion when viewed from the first direction. Energy storage device.

2. A storage element having electrode terminals arranged in a first direction; a bus bar joined to the electrode terminal, The bus bar is a busbar main body having a joint portion joined to the electrode terminal by laser welding; a first wall portion extending in the first direction from the busbar main body; a second wall portion at least partially overlapping with the busbar main body portion when viewed from the first direction and disposed in a position facing the busbar main body portion, further comprising an insulating member disposed between the busbar body and the second wall portion. Energy storage device.

3. The second wall portion is provided upright from an end portion of the first wall portion opposite to the busbar main body portion in a direction intersecting the first wall portion. The electricity storage device according to claim 1 or 2.

4. the busbar main body includes a protruding portion provided at a position not overlapping with the second wall portion when viewed from the first direction, the protruding portion protruding in a second direction intersecting the first direction, The power storage device according to any one of claims 1 to 3.

5. The busbar main body is joined to the electrode terminals of the two energy storage elements arranged side by side. The power storage device according to any one of claims 1 to 4.

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