Battery module

Abstract

This battery module includes: a module body in which a plurality of flat rectangular cells having a rectangular shape when viewed in a thickness direction are stacked; a first conductor extending in a stacking direction of the rectangular cells and disposed on a first surface on which long side portions of the plurality of rectangular cells in the module body are arranged; and a second conductor extending from the first conductor in a direction intersecting the stacking direction and toward a terminal on a second surface on which short side portions of the plurality of rectangular cells in the module body are arranged. The second conductor includes an excess-length portion extending along a path having a longer conductor length than a right-angled reference path along the first surface and the second surface.

Description

Battery Module

[0001] The present invention relates to a battery module. The present application claims priority based on Japanese Patent Application No. 2025-051538 filed in Japan on March 26, 2025, the content of which is incorporated herein by reference.

[0002] Patent Document 1 describes that a busbar module is disposed on an upper surface of a battery module in which a plurality of unit cells are stacked, the busbar module is formed of a flexible printed circuit (FPC), and includes a main line extending in a stacking direction and a branch line portion extending in a direction intersecting the stacking direction, wherein the branch line portion is bent in the stacking direction.

[0003] Patent Document 2 describes that a Battery Management System (BMS) is disposed on an upper surface of a battery cell stack, and a terminal plate connected to electrode terminals on a side surface of the battery cell stack and the BMS is bent along the upper surface and the side surface of the battery cell stack.

[0004] Patent Document 3 describes that clamping plates are disposed on left and right sides of a cell stack of a battery module in which a plurality of cells are stacked, and clamping plate elastic portions extending along an upper surface of the cell stack are formed by a plurality of elastic pieces arranged in a front-rear direction.

[0005] Japanese Unexamined Patent Publication No. 2020-205177 Japanese National Publication of International Patent Application No. 2018-519651 Japanese Unexamined Patent Publication No. 2020-129527

[0006] The present invention provides a battery module that can easily absorb path variations of a conductor extending from a first surface of a module body toward a second surface intersecting the first surface of the module body.

[0007] As a means of solving the above problems, an aspect of the present invention has the following configuration. A battery module according to one aspect of the present invention comprises a module body formed by stacking a plurality of flattened prismatic cells that are rectangular in shape when viewed from the thickness direction; a first conductor extending in the stacking direction of the prismatic cells and arranged on a first surface of the module body where the long sides of the plurality of prismatic cells are lined up; and a second conductor extending from the first conductor in a direction intersecting the stacking direction and extending toward the terminals on a second surface of the module body where the short sides of the plurality of prismatic cells are lined up, wherein the second conductor has an extra length portion that extends along a path that is longer than a right-angled reference path along the first and second surfaces.

[0008] According to an aspect of the present invention, it is possible to easily absorb path variations of conductors extending from the first surface of the module body toward a second surface of the module body that intersects with the first surface.

[0009] This is an exploded perspective view showing the schematic configuration of the energy storage device according to this embodiment. This is a perspective view of the energy storage unit of the above energy storage device. This is a front view of the energy storage unit of Figure 2. This is a top view of the energy storage unit of Figure 2. This is a bottom view of the energy storage unit of Figure 2. This is a left side view of the energy storage unit of Figure 2. This is a cross-sectional view taken along line VII-VII in Figure 6. This is a cross-sectional view corresponding to Figure 7A in the comparative example. This is a perspective view showing the area around the excess length of the second conductor of the energy storage device. This is a partially enlarged view of Figure 7A, showing a cross-sectional view in detail of the excess length. This is a cross-sectional view corresponding to Figure 9A showing a modified example of the area around the excess length.

[0010] (1) A battery module according to one aspect of the present invention comprises a module body formed by stacking a plurality of flattened prismatic cells that are rectangular in shape when viewed from the thickness direction; a first conductor extending in the stacking direction of the prismatic cells and positioned on a first surface of the module body where the long sides of the plurality of prismatic cells are aligned; and a second conductor extending from the first conductor in a direction intersecting the stacking direction and extending toward the terminals on a second surface of the module body where the short sides of the plurality of prismatic cells are aligned, wherein the second conductor has an extra length portion that extends along a path that is longer than a right-angled reference path along the first and second surfaces.

[0011] According to the battery module described in (1) above of the present invention, the second conductor extending from the first conductor along the first surface of the module body toward the terminals located on the second surface of the module body has an excess length longer than the right-angled reference path, so that the second conductor extending across two right-angled surfaces of the module body can be configured to easily absorb tolerances in the relative positions of the first conductor and the terminals.

[0012] (2) In the battery module described in (1) above, the excess length portion may be formed to bulge outward from the reference path when viewed from the stacking direction.

[0013] According to the battery module described in (2) above of the present invention, the excess length of the second conductor is formed in a curved shape that bulges outward (away from the module body) from the right-angled reference path along the first and second surfaces, making it easier to create slack in the second conductor.

[0014] (3) In the battery module described in (1) or (2) above, the terminals are arranged on at least one side in the longitudinal direction along the long side of the module body, the second conductor extends to at least one side in the longitudinal direction and reaches the terminals, and the module includes a side member that extends in the stacking direction and is arranged on at least one side in the longitudinal direction of the module body, and an opening may be formed in the portion of the side member that overlaps with the excess length.

[0015] According to the battery module described in (3) above of the present invention, terminals and a side member are provided on at least one side in the longitudinal direction of the module body, and an opening is formed in the side member in a part corresponding to the excess length of the second conductor so as to avoid the excess length. As a result, even if the excess length curves outward from the module body, this bulge is less likely to interfere with the side member, and it becomes easier to create slack in the second conductor.

[0016] (4) In the battery module described in (3) above, the side member comprises a first side piece along the first surface and a second side piece along the second surface, and the opening may be provided spanning the first side piece and the second side piece and form a closed hole on the outer circumference.

[0017] According to the battery module described in (4) above of the present invention, by forming an opening that spans the first and second surfaces and has a closed outer circumference in a side member having a first side piece along the first surface and a second side piece along the second surface, it is possible to easily expand the excess length and suppress the effect on the strength and rigidity of the side member caused by providing the opening.

[0018] (5) In the battery module described in any one of (1) to (4) above, the excess length portion may bulge out more on the second surface side than on the first surface side when viewed from the stacking direction.

[0019] According to the battery module described in (5) above of the present invention, the excess length of the second conductor bulges out more on the second surface side than on the first surface side, thereby suppressing the increase in dimensions on the first surface side due to the excess length, and allowing the excess length to be arranged by utilizing the space secured on the second surface side according to terminals, etc.

[0020] Hereinafter, a battery module according to an embodiment (including its modifications) of the present invention will be described with reference to the drawings. The embodiments described below are all general or specific examples. The numerical values, shapes, materials, components, arrangement and connection configurations of components, manufacturing processes, and the order of manufacturing processes shown in the following embodiments are examples and are not intended to limit the present invention. In each figure, dimensions, etc., are not strictly illustrated. In each figure, the same or similar components are denoted by the same reference numeral.

[0021] In the following description and drawings, the direction along the long side of the rectangular shape of the flattened energy storage element when viewed from the thickness direction (longitudinal direction), or the left-right direction, is defined as the X-axis direction. The direction along the thickness of the energy storage element, the stacking direction of the multiple energy storage elements in the energy storage unit, or the front-back direction is defined as the Y-axis direction. The direction along the short side of the rectangular shape of the energy storage element (short side direction), or the up-down direction, is defined as the Z-axis direction. These X-axis, Y-axis, and Z-axis directions are mutually orthogonal. Depending on the usage, the Z-axis direction may not be the up-down direction, but for the sake of explanation below, the Z-axis direction will be described as the up-down direction.

[0022] In the following descriptions and diagrams, the arrow on the X-axis indicates leftward, and the opposite direction indicates rightward. The term "X-axis direction" simply refers to both left and right. The arrow on the Y-axis indicates forward, and the opposite direction indicates backward. The term "Y-axis direction" simply refers to both forward and backward. The arrow on the Z-axis indicates upward, and the opposite direction indicates downward. The term "Z-axis direction" simply refers to both up and down.

[0023] Expressions indicating relative directions or orientations, such as parallel and orthogonal, include cases where the directions or orientations are not strictly accurate. For example, two directions being parallel does not only mean that the two directions are perfectly parallel, but also that they are substantially parallel, i.e., they may have a difference of a few percent. In the following explanation, "insulation" refers to "electrical insulation."

[0024] <Energy Storage Device 1> First, the configuration of the energy storage device 1 in this embodiment will be described. Figure 1 is an exploded perspective view showing the schematic configuration of the energy storage device 1 according to this embodiment. Figure 2 is a perspective view of the energy storage unit 10 of the energy storage device 1. Figure 3 is a front view of the energy storage unit 10, Figure 4 is a top view of the energy storage unit 10, Figure 5 is a bottom view of the energy storage unit 10, and Figure 6 is a left side view of the energy storage unit 10.

[0025] The energy storage device 1 is a device that can charge electricity from an external source and discharge electricity to an external source. The energy storage device 1 is used for power storage or power supply purposes. The energy storage device 1 is used as a battery for driving or starting the engine of mobile vehicles such as automobiles, motorcycles, watercraft, ships, snowmobiles, agricultural machinery, construction machinery, or railway vehicles for electric railways.

[0026] Examples of the above-mentioned vehicles include electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and fossil fuel (gasoline, diesel, liquefied natural gas, etc.) vehicles. Examples of the above-mentioned railway vehicles for electric railways include electric trains, monorails, maglev trains, and hybrid trains equipped with both diesel engines and electric motors. The energy storage device 1 can also be used as a stationary battery for household or commercial use, etc.

[0027] The energy storage device 1 comprises an energy storage unit 10 and a unit case 12 that houses the energy storage unit 10. The energy storage device 1 is equipped with external terminals (positive external terminal and negative external terminal) for electrical connection to external devices. The energy storage device 1 may also be equipped with a circuit board and electrical equipment such as relays for monitoring or controlling the charging and discharging states of the energy storage unit 10.

[0028] The energy storage unit 10 is a battery module (battery pack) having a plurality of energy storage elements 100. The energy storage unit 10 has a roughly rectangular parallelepiped shape that is long in the Y-axis direction by stacking the plurality of energy storage elements 100 in the Y-axis direction (front-to-back direction). The energy storage unit 10 is equipped with busbars, etc., for connecting the plurality of energy storage elements 100 in series or in parallel. The busbars, etc., may connect all of the energy storage elements 100 in series, or any of the energy storage elements 100 may be connected in parallel and then connected in series, or all of the energy storage elements 100 may be connected in parallel.

[0029] The energy storage element 100 is a secondary battery (single cell) that can charge and discharge electricity, and more specifically, a non-aqueous electrolyte secondary battery such as a lithium-ion secondary battery. The energy storage element 100 has a flattened rectangular parallelepiped shape (square, prism) in the Y-axis direction. In this embodiment, multiple energy storage elements 100 are arranged in line in the Y-axis direction, but the number of energy storage elements 100 is not particularly limited.

[0030] The energy storage element 100 is not limited to a non-aqueous electrolyte secondary battery, but may be a secondary battery other than a non-aqueous electrolyte secondary battery, or a capacitor. The energy storage element 100 may not be a secondary battery, but a primary battery that allows the user to use the stored electricity without charging. The energy storage element 100 may be a battery using a solid electrolyte. The energy storage element 100 may be a pouch-type battery.

[0031] The unit case (module case) 12 that houses the energy storage unit 10 is a roughly rectangular parallelepiped (box-shaped) container that constitutes the outer casing (shell) of the energy storage device 1. The unit case 12 is positioned outside the energy storage unit 10, fixing the energy storage unit 10 in a predetermined position and protecting it from impacts and the like.

[0032] The unit case 12 is a metal case formed from a metal component such as aluminum, aluminum alloy, stainless steel, iron, or plated steel sheet. For example, the unit case 12 is formed from aluminum die casting. The unit case 12 may also be formed from a high-strength resin material (insulating material).

[0033] <Energy Storage Unit 10> As shown in Figures 1 to 6, the energy storage element 100 has a flattened shape with its thickness direction oriented in the front-to-back direction. When viewed from the thickness direction, the energy storage element 100 has a rectangular shape that is long in the left-to-right direction. The energy storage element 100 constitutes a rectangular cell when viewed from the thickness direction. The positive and negative terminals 106 of the energy storage element 100 are distributed and arranged on the left and right side portions (short side portions 102). A gas discharge valve 107 is arranged on at least one of the left and right side portions. The explanation of the internal structure of the energy storage element 100 is omitted.

[0034] The energy storage element 100 is arranged with its longitudinal direction (long side) aligned with the longer side 116 of the rectangular shape (long side) in the left-right direction (X direction), its short side 102 aligned with the shorter side (short side) in the up-down direction (Z direction), and its thickness direction aligned with the front-back direction (Y direction).

[0035] The module body 110 is formed by stacking multiple energy storage elements 100 so that they overlap in the thickness direction (Y direction). Hereinafter, the Y direction may be referred to as the stacking direction of the module body 110. A pair of end plates (end members) 115 are arranged on the outermost surfaces 111 on both sides of the stacking direction of the module body 110.

[0036] For example, the end plate 115 is not limited to an actual plate material, but may be a virtual plate material formed by arranging a frame of multiple beams in a plate shape. For example, each end plate 115 may be a rectangular plate shape that overlaps with the energy storage element 100 when viewed from the stacking direction (see Figure 7).

[0037] A bind bar (connecting member) 120 extends between the central parts of the rectangular long sides 101 of the end plates 115 on both sides in the stacking direction. Both ends 121 of the bind bar 120 in the longitudinal direction (stacking direction) are fastened to the central parts of the long sides 101 of the end plates 115 on both sides in the stacking direction.

[0038] Hereinafter, the upper and lower long sides 116 of each end plate 115 may be referred to as the upper side 116a and the lower side 116b, respectively. The upper and lower long sides 101 of each energy storage element 100 may be referred to as the upper side 101a and the lower side 101b, respectively.

[0039] The virtual surface extending between the upper edges 116a of the end plates 115 on both sides in the stacking direction is defined as the horizontal upper surface 112a of the module body 110, and the virtual surface extending between the lower edges 116b of the end plates 115 on both sides in the stacking direction is defined as the horizontal lower surface 112b of the module body 110. The upper and lower surfaces 112a and 112b are sometimes collectively referred to as the first surface 112.

[0040] The upper and lower surfaces 112a and 112b of the module body 110 have the rectangular long sides 101 (upper and lower sides 101a and 101b) of multiple energy storage elements 100 arranged in a row. The direction along the long sides 101 and 116 of each energy storage element 100 and each end plate 115 is defined as the longitudinal direction of the energy storage element 100 and the end plate 115 (and consequently the module body 110).

[0041] Among directions (horizontal directions) along the first surface 112 of the module body 110, the stacking direction is defined as the front-rear direction (Y-axis direction), and the direction intersecting (perpendicular to) the stacking direction is defined as the left-right direction (X-axis direction). The direction intersecting (perpendicular to) the first surface 112 is defined as the up-down direction (Z-axis direction).

[0042] In addition, the left and right short side portions 102 of each power storage element 100 may be referred to as a left side 102a and a right side 102b, respectively. The left and right short side portions 117 of each end plate 115 may be referred to as a left side 117a and a right side 117b, respectively.

[0043] A virtual surface extending between the left sides 117a of the end plates 115 on both sides in the stacking direction is defined as a vertical left side surface 113a of the module body 110, and a virtual surface extending between the right sides 117b of the end plates 115 on both sides in the stacking direction is defined as a vertical right side surface 113b of the module body 110. The left and right side surfaces 113a and 113b may be collectively referred to as a second surface 113.

[0044] On the left and right side surfaces 113a and 113b of the module body 110, the rectangular short side portions 102 (left and right side portions 102a and 102b) of the plurality of power storage elements 100 are arranged. The direction along each of the short side portions 102 and 117 of each power storage element 100 and each end plate 115 is defined as the widthwise direction of the power storage element 100 and the end plate 115 (and thus the module body 110).

[0045] The arrangement of the module body 110 described above is an example, and for example, an arrangement in which the longitudinal direction of the module body 110 is inclined or vertical instead of horizontal may be adopted.

[0046] <Bind Bar 120> As shown in FIGS. 1 to 6, between the upper sides 116a and between the lower sides 116b of the end plates 115 on both sides in the stacking direction are connected by bind bars 120 extending in the stacking direction, respectively. Each bind bar 120 is provided along the upper surface 112a or the lower surface 112b of the module body 110. Each bind bar 120 has a plate shape (belt shape) along the upper surface 112a or the lower surface 112b of the module body 110.

[0047] Each binding bar 120 extends in the stacking direction, and both end portions 121 in the length direction are respectively fastened to the end plates 115 on both sides in the stacking direction. Both end portions 121 of each binding bar 120 are fixed to the corresponding end plate 115 by, for example, fastening using a bolt B1 along the stacking direction. Note that the end plate 115 and the binding bar 120 may be fastened by being joined via welding, an adhesive, or the like.

[0048] The upper and lower binding bars 120 are provided, for example, vertically symmetrically. Each binding bar 120 is formed symmetrically, for example, in the length direction (the stacking direction). Each of the front and rear end portions 121 of each binding bar 120 includes a first piece 121a along the first surface 112 of the module body 110, and a second piece 121b along the outermost surface 111 of the end plate 115. The front and rear end portions 121 of each binding bar 120 are each bent into an L-shape when viewed from the left-right direction and integrally formed.

[0049] For the front and rear end portions 121 of each binding bar 120, the full width H2 in the left-right direction is smaller than the full width H1 of the power storage element 100 in the left-right direction (and consequently the full width of the module body 110). By suppressing the full width H2 of the end portions 121 of the binding bar 120, the fastening portion to the module body 110 can be downsized to reduce the weight of the binding bar 120, and deformation of the central portion of the end plate 115 in the longitudinal direction can be efficiently suppressed.

[0050] For the intermediate portion 122 between the front and rear end portions 121 (inside in the front-rear direction) of each binding bar 120, the full width H3 in the left-right direction is smaller than the full width H2 of the end portions 121 in the left-right direction. By suppressing the full width H3 of the intermediate portion 122 of the binding bar 120, further size and weight reduction of the binding bar 120 can be achieved, and the first surface 112 of the module body 110 can be easily exposed to improve heat dissipation. Arrangement of a first conductor 131, which will be described later, is also facilitated.

[0051] On the inner side in the front-rear direction at the end portion 121 of each binding bar 120, a gradually changing portion 123 in which the left-right width becomes narrower toward the inner side in the front-rear direction is formed. Since the end portion 121 of the binding bar 120 is connected to the intermediate portion 122 via the gradually changing portion 123, stress concentration between the end portion 121 and the intermediate portion 122 is alleviated.

[0052] Each bind bar 120 is formed into a predetermined shape by press-forming a steel plate. Each bind bar 120 is formed in a planar shape, except for, for example, the front and rear second pieces 121b that are aligned with the end plate 115. The "planar shape" may include irregularities that are smaller in the vertical direction than the second pieces 121b. By making the bind bars 120 planar, the vertical direction width of the energy storage unit 10 including the bind bars 120 is reduced.

[0053] <Side Plate 125> As shown in Figures 1 to 6, the left side 117a and the right side 117b of the end plates 115 on both sides in the stacking direction are connected by side plates (side members) 125 that extend in the stacking direction. The front and rear ends of the left and right side plates 125 are fixed to the left and right sides of the front and rear end plates 115, respectively, by bolt fastening or the like.

[0054] The energy storage unit 10 comprises a pair of left and right side plates 125 and a pair of front and rear end plates 115. The front and rear end plates 115 and the left and right side plates 125 are connected in a frame shape that surrounds the outer circumference of the module body 110 in a plan view. Multiple energy storage elements 100 in the module body 110 are constrained in a stacked state by the front and rear end plates 115 and the left and right side plates 125. The central part in the longitudinal direction of the module body 110 is constrained in a stacked state by upper and lower bind bars 120.

[0055] The module body 110 is integrated by the front and rear end plates 115, the left and right side plates 125, and the upper and lower binding bars 120, making it easier to handle the energy storage unit 10 as a single unit. The front and rear end plates 115 and the left and right side plates 125 form the outer frame, making the energy storage unit 10 robust against inputs from both inside and outside.

[0056] Each of the left and right side plates 125 includes a first side piece 125a that follows the first surface 112 of the module body 110, and a second side piece 125b that follows the second surface 113 of the module body 110. The first side piece 125a and the second side piece 125b of the side plate 125, which extend in the stacking direction, align the vertical and horizontal positions of the multiple energy storage elements 100.

[0057] As shown in Figures 2 and 6, an opening may be formed in the first side piece 125a of the side plate 125 to expose the gas discharge valve 107 of each energy storage element 100. In the illustrated example, the left and right side plates 125 are formed asymmetrically in the vertical direction, but they may also be formed symmetrically in the vertical direction.

[0058] Each of the left and right side plates 125 is formed into a predetermined shape by press-forming a steel plate. Multiple openings 129, described later, are formed at intervals in the stacking direction in the bent portion 125c between the first side piece 125a and the second side piece 125b of the side plate 125.

[0059] The following describes the configuration of the connections between the multiple energy storage elements 100 in the embodiment. Figure 7A is a cross-sectional view taken along line VII-VII in Figure 6, schematically showing the connection state between the first conductor 131 on the module body 110 and the terminal 106 in the embodiment. Figure 7B is a cross-sectional view similar to Figure 7A, showing a comparative example of the embodiment. Figure 8 is a perspective view showing the main part of the second conductor 132 in the embodiment. Figure 9A is a cross-sectional view showing the main part of Figure 7A. Figure 9B is a cross-sectional view showing a modified example of Figure 9A.

[0060] As shown in Figures 2 and 4, a first conductor 131 extending in the stacking direction is arranged on the first surface 112. The first conductor 131 is strip-shaped along the first surface 112 and is provided in pairs on the left and right sides, flanking the left and right centers of the first surface 112. The first conductor 131 is a flexible printed circuit board (FPC). The pair of left and right first conductors 131 are arranged, for example, between the left and right centers of the first surface 112 and the left and right outer edges, and are spaced apart from each other in the left-right direction.

[0061] As shown in Figures 7A and 8, the base ends (inner ends in the left-right direction) of a plurality of second conductors 132 extending outward in the left-right direction are connected to the first conductor 131. The second conductors 132 are flexible, tape-shaped conductors that, after reaching the left and right outer ends of the first surface 112, bend downward and extend downward along the second surface 113. The tip (lower end) of the downwardly bent second conductor 132 is connected to the terminal 106 of a specified rectangular cell 100 via a busbar 106a and a relay piece 106b.

[0062] The second conductor 132 extends outward from the first conductor 131 in the left-right direction and bends toward the terminal 106 on the second surface 113. For example, multiple rectangular cells 100 form one or more groups by connecting their terminals 106 to each other via busbars 106a, etc. One second conductor 132 extends to each group of rectangular cells 100 and is connected to the busbars 106a via relay pieces 106b. For example, the second conductor 132 may be configured to extend and connect individually toward the terminal 106 of each rectangular cell 100.

[0063] Referring also to Figure 9A, the second conductor 132 is routed along a first path 132a parallel to the first surface 112 and a second path 132b parallel to the second surface 113, ignoring slack and misalignment. The right-angled path connecting the first path 132a and the second path 132b is referred to as the reference path 132c. In this embodiment, the second conductor 132 extends longer than the reference path 132c to account for path variations. Therefore, the second conductor 132 has a slack excess length 135 relative to the reference path 132c.

[0064] The excess length portion 135 is formed in a curved shape that bulges outward (away from the rectangular cell 100) from the reference path 132c when viewed from the stacking direction. By forming the excess length portion 135 away from the upper outer corner portion 110a of the rectangular cell 100 (module body 110), contact of the second conductor 132 with the corner portion 110a is suppressed.

[0065] As shown in Figure 7B, in a configuration where the terminals 106 of the rectangular cell 100 are arranged on the first surface 112 of the module body 110, the second conductor 132 only needs to extend from the first conductor 131 along the first surface 112, and the variation in the path of the second conductor 132 can be kept small.

[0066] As shown in Figure 7A, in a configuration where the terminals 106 of the rectangular cell 100 are arranged on the second surface 113 of the module body 110, the second conductor 132 bends and extends from the first conductor 131 on the first surface 112 toward the terminals 106 on the second surface 113. For this reason, the path of the second conductor 132 tends to vary greatly, and it is necessary to ensure a large margin for absorbing path variations.

[0067] In this embodiment, by providing a slackened excess length portion 135 that bulges out relative to the reference path 132c, the second conductor 132 extends along a longer path compared to the right-angled reference path 132c. This ensures that even when the second conductor 132 extends across two orthogonal surfaces, there is room to absorb path variations.

[0068] Referring to Figure 9A, the excess portion 135 is formed at the corner 110a where the first surface 112 and the second surface 113 intersect in the module body 110. When viewed from the stacking direction, the excess portion 135 bulges upward by an allowance B2 from the portion along the first surface 112 (the connection portion with the first conductor 131) and bulges outward to the left and right by an allowance B3 from the portion along the second surface 113 (the connection portion with the terminal 106, bus bar 106a, or relay piece 10b). The excess portion 135 is formed such that the allowance B3 to the left and right bulges outward is larger than the allowance B2 to the upward bulge.

[0069] By suppressing the bulge of the module body 110 toward the first surface 112 side in the excess length portion 135, the excess length portion 135 is less likely to interfere with other components adjacent to the first surface 112. Since the terminals 106 and busbars 106a, etc. are arranged on the second surface 113 side of the module body 110, it is easy to secure space for the excess length portion 135 and to form a curved path for the excess length portion 135.

[0070] In the left-right direction, the side plate 125 on the side where the excess length portion 135 is provided has an opening 129 formed so as to overlap with the excess length portion 135. Multiple openings 129 are formed in the side plate 125 at intervals in the stacking direction. Each opening 129, in the side plate 125 which extends in an L-shape in cross-section along the corner portion 110a of the module body 110, partially exposes the corner portion 110a of the module body 110 to the outside of the side plate 125. At least one opening 129 is located in a position that overlaps with the excess length portion 135 of the second conductor 132 in the front-rear direction. This opening 129 makes it less likely for the excess length portion 135 that bulges outward from the corner portion 110a to interfere with the inside of the side plate 125.

[0071] As shown in Figure 9B, the first conductor 131 and the second conductor 132 are covered from the outside of the module body 110 by the insulating cover 133. The opening 129 in the side plate 125 makes it less likely for the insulating cover 133, along with the excess length 135 of the second conductor 132, to interfere with the inside of the side plate 125. As shown in Figure 9B, the excess length 135 of the second conductor 132 may be made without any upward bulge.

[0072] The opening 129 penetrates the side plate 125 from the inside to the outside as a hole with a closed inner periphery. This reduces the impact on the strength and rigidity of the side plate 125 compared to, for example, a case where a notched opening 129 is provided on the outer edge of the side plate 125 (without the inner periphery being closed).

[0073] The energy storage unit (battery module) 10 of this embodiment described above comprises a module body 110 formed by stacking a plurality of flattened rectangular cells 100 that are rectangular in shape when viewed from the thickness direction; a first conductor 131 extending in the stacking direction of the rectangular cells 100 and positioned on a first surface 112 of the module body 110 where the long sides of the plurality of rectangular cells 100 are aligned; and a second conductor 132 extending from the first conductor 131 in a direction intersecting the stacking direction and extending toward the terminal 106 of a second surface 113 of the module body 110 where the short sides of the plurality of rectangular cells 100 are aligned. The second conductor 132 includes an extra length portion 135 that extends along a path that is longer than the L-shaped reference path 132c along the first surface 112 and the second surface 113.

[0074] With this configuration, the second conductor 132, which extends from the first conductor 131 along the first surface 112 of the module body 110 toward the terminal 106 located on the second surface 113 of the module body 110, has an excess length 135 that is longer than the right-angled reference path 132c. This configuration allows the second conductor 132, which extends across two right-angled surfaces of the module body 110, to easily absorb tolerances in the relative positions of the first conductor 131 and the terminal 106.

[0075] Furthermore, in the energy storage unit 10, the excess portion 135 is formed to bulge outward from the reference path 132c when viewed from the stacking direction.

[0076] With this configuration, the excess length portion 135 of the second conductor 132 is formed in a curved shape that bulges outward (away from the module body 110) from the L-shaped reference path 132c that runs along the first surface 112 and the second surface 113, making it easier to create slack in the second conductor 132.

[0077] Furthermore, in the energy storage unit 10, the terminal 106 is located on at least one side in the longitudinal direction along the long side of the module body 110, the second conductor 132 extends to at least one side in the longitudinal direction and reaches the terminal 106, and the unit includes a side plate 125 that extends in the stacking direction and is located on at least one side in the longitudinal direction of the module body 110, with an opening 129 formed in the portion of the side plate 125 that overlaps with the excess length portion 135.

[0078] According to this configuration, the module body 110 is provided with terminals 106 and a side plate 125 on at least one side in the longitudinal direction. An opening 129 is formed in the side plate 125 in a portion corresponding to the excess length 135 of the second conductor 132, so as to avoid the excess length 135. This makes it less likely for the excess length 135 to bend outward from the module body 110, and makes it easier to create slack in the second conductor 132.

[0079] Furthermore, in the energy storage unit 10, the side plate 125 comprises a first side piece 125a along the first surface 112 and a second side piece 125b along the second surface 113, and the opening 129 is provided spanning the first side piece 125a and the second side piece 125b and forms a closed hole on its outer circumference.

[0080] With this configuration, by forming an opening 129 that spans both the first surface 112 and the second surface 113 and has a closed outer circumference in the side plate 125 which has a first side piece 125a along the first surface 112 and a second side piece 125b along the second surface 113, it is possible to easily expand the excess length portion 135 and to suppress the effect of providing the opening 129 on the strength and rigidity of the side plate 125.

[0081] Furthermore, in the energy storage unit 10, the excess portion 135 bulges out more towards the second surface 113 than towards the first surface 112 when viewed from the stacking direction.

[0082] With this configuration, the excess length portion 135 of the second conductor 132 bulges more significantly towards the second surface 113 than towards the first surface 112. This allows the excess length portion 135 to be positioned on the second surface 113 using the space secured according to the terminals 106, etc., while suppressing the increase in dimensions on the first surface 112 side due to the excess length portion 135.

[0083] Although the present disclosure has been described above with reference to embodiments, the present disclosure is not limited to the embodiments described above. Various modifications can be made to the structure and details of the present disclosure as can be understood by those skilled in the art. Furthermore, each embodiment can be combined with other embodiments as appropriate.

[0084] For example, the configuration is not limited to having a pair of end plates (end members); for example, an end plate may be provided on only one side in the stacking direction, and the other side in the stacking direction may be supported by a module case or the like. The configuration is not limited to having a pair of bind bars; for example, a bind bar may be provided on only one side, top or bottom. The configuration is not limited to having a pair of side plates; for example, a side plate may be provided on only one side, left or right, and the other side in the stacking direction may be supported by a module case or the like. The side plates are not limited to a configuration that restrains the top and bottom of the side of the module body; they may restrain only one side, top or bottom. The ends of the bind bars are not limited to a shape that embraces the end members; for example, they may be directly fastened to the end members as screw shafts along the stacking direction.

[0085] The present invention is not limited to the embodiments described above, and includes various modifications to the embodiments described above, without departing from the spirit of the invention. Forms constructed by arbitrarily combining the components of the above embodiments and their modifications are also included within the scope of the present invention.

[0086] This invention can be applied to battery modules that stack multiple prismatic cells, such as lithium-ion secondary batteries.

[0087] 1...Energy storage device 10...Energy storage unit (battery module) 100...Energy storage element (prismatic cell) 101...Long side 102...Short side 106...Terminal 110...Module body 112...First surface 113...Second surface 125...Side plate (side member) 125a...First side piece 125b...Second side piece 129...Opening 131...First conductor 132...Second conductor 132c...Reference path 135...Excess length

Claims

1. A battery module comprising: a module body formed by stacking a plurality of flattened rectangular cells that are rectangular in shape when viewed from the thickness direction; a first conductor extending in the stacking direction of the rectangular cells and positioned on a first surface of the module body where the long sides of the plurality of rectangular cells are aligned; and a second conductor extending from the first conductor in a direction intersecting the stacking direction and extending toward the terminals on a second surface of the module body where the short sides of the plurality of rectangular cells are aligned, wherein the second conductor has an extra length portion that extends along a path that is longer than a right-angled reference path along the first and second surfaces.

2. The battery module according to claim 1, wherein the excess portion is formed to bulge outward from the reference path when viewed from the stacking direction.

3. The battery module according to claim 1 or 2, wherein the terminal is located on at least one side in the longitudinal direction along the long side of the module body, the second conductor extends to at least one side in the longitudinal direction and reaches the terminal, and the module includes a side member that extends in the stacking direction and is located on at least one side in the longitudinal direction of the module body, and an opening is formed in the portion of the side member that overlaps with the excess length.

4. The battery module according to claim 3, wherein the side member comprises a first side piece along the first surface and a second side piece along the second surface, and the opening is provided spanning the first side piece and the second side piece and forms a closed hole on the outer circumference.

5. The battery module according to claim 1 or 2, wherein the excess portion bulges out more on the second surface side than on the first surface side when viewed from the stacking direction.

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