Energy storage device

Abstract

A power storage device (1) comprises: a terminal (81); a conductive member (33c) that is electrically connected to a power storage element (21) and fastened to the terminal (81); a fixing section (121) for fixing one of the terminal (81) and the conductive member (33c) to a predetermined position on the power storage device (1); and a holding section (28c) for holding the other of the terminal (81) and the conductive member (33c). The holding section (28c) has a structure that makes it possible for one of the conductive member (33c) and the terminal (81) to slide with respect to the other prior to fastening of the conductive member (33c) to the terminal (81).

Description

Technical Field

[0001] The present invention relates to a power storage device including a power storage element and an exterior body.

Background Art

[0002] Conventionally, in a power storage device, there is known one including a terminal fixed at a predetermined position of the power storage device, a power storage element, and a conductive member connecting the terminal and the power storage element.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above conventional power storage device, when the terminal is fixed at a predetermined position when fastening the terminal and the conductive member, stress concentrates on a part of the conductive member due to the fastening, increasing the mechanical load and causing damage, and as a result, there is a risk of impairing the reliability of the power storage device.

[0005] The present invention has been made by the inventor of the present application newly paying attention to the above problems, and an object thereof is to suppress a decrease in the reliability of a power storage device.

Means for Solving the Problems

[0006] A power storage device according to an aspect of the present invention is a power storage device having a power storage element, including a terminal, a conductive member electrically connected to the power storage element and fastened to the terminal, a fixing portion for fixing one of the terminal and the conductive member at a predetermined position of the power storage device, and a holding portion for holding the other of the terminal and the conductive member, and the holding portion has a structure in which the other is slidable with respect to the one in a state before the conductive member is fastened to the terminal.

Effects of the Invention

[0007] The energy storage device according to the present invention can suppress the deterioration of the reliability of the energy storage device. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a perspective view showing the external appearance of an energy storage device according to an embodiment. [Figure 2] Figure 2 is an exploded perspective view showing the components of the energy storage device according to the embodiment when it is disassembled. [Figure 3] Figure 3 is an exploded perspective view showing the schematic configuration of the energy storage unit according to the embodiment. [Figure 4] Figure 4 is a perspective view showing the assembled state of the external terminal, busbar, and busbar mounting section according to the embodiment. [Figure 5] Figure 5 is a perspective view showing the busbar mounting portion according to the embodiment. [Figure 6] Figure 6 is a partial cross-sectional view showing the assembled state of the external terminal, busbar, and busbar mounting part according to the embodiment. [Figure 7] Figure 7 is a partial cross-sectional view showing the assembled state of the external terminals, busbars, and retaining parts according to a modified example. [Modes for carrying out the invention]

[0009] An energy storage device according to one aspect of the present invention is an energy storage device having an energy storage element, comprising a terminal, a conductive member electrically connected to the energy storage element and fastened to the terminal, a fixing part for fixing one of the terminal and the conductive member to a predetermined position in the energy storage device, and a holding part for holding the other of the terminal and the conductive member, wherein the holding part has a structure that allows the other to slide relative to the one before the conductive member is fastened to the terminal.

[0010] According to this design, one of the terminal and the conductive member is fixed by a fixing part, while the other is held slidably relative to the other by a holding part before fastening. Therefore, when the terminal and the conductive member are fastened together, the fastening force causes the other to slide. This reduces stress concentration on the conductive member or terminal, thereby suppressing damage to the conductive member or terminal. Consequently, it is possible to suppress a decrease in the reliability of the energy storage device.

[0011] The retaining part may have a structure into which the other part is fitted.

[0012] According to this design, since the other part is fitted into the retaining part, the movement of the other part can be restricted to some extent before fastening. Therefore, the stability of the fastening process can be improved. If the stability of the fastening process is improved, the deterioration of the reliability of the energy storage device can be further suppressed.

[0013] The retaining portion may have a structure that allows rotation in a direction intersecting the other sliding direction, before the conductive member is fastened to the terminal.

[0014] According to this design, since the retaining part allows the other part to rotate, the other part can rotate in addition to sliding during fastening. This increases the degree of freedom of movement of the other part during fastening. As a result, stress concentration on the conductive member or terminal can be further reduced, and damage to the conductive member or terminal can be more reliably suppressed. Therefore, the deterioration of the reliability of the energy storage device can be further suppressed.

[0015] The other sliding direction in the retaining portion may be the direction aligned with the fastening direction at the time of fastening.

[0016] According to this, the sliding direction of the other part in the holding section and the fastening direction during fastening are aligned with each other, allowing the other part to slide smoothly during fastening. This further reduces stress concentration on the terminal or conductive member, and more reliably suppresses damage to the terminal or conductive member. Therefore, the deterioration of the reliability of the energy storage device can be further suppressed.

[0017] The power storage device includes a fastening member for fastening a conductive member, and the holding portion holds the conductive member slidably and allows the conductive member to slide in a direction approaching the fastening member when the conductive member is fastened to the terminal by the fastening member.

[0018] According to this, since the holding portion allows the conductive member to slide in a direction approaching the fastening member when the conductive member is fastened to the terminal, the conductive member moves so as to approach the fastening member by the fastening. That is, since the conductive member can be actively moved by the fastening, stress concentration on the conductive member can be further alleviated. Therefore, a decrease in the reliability of the power storage device can be further suppressed.

[0019] The holding portion holds the conductive member slidably, and a cable electrically connected to the power storage element is assembled to the conductive member.

[0020] According to this, since the conductive member to which the cable is assembled is held slidably by the holding portion, it can be held while allowing the slide of the conductive member that is easily moved by receiving the deformation of the cable. Therefore, even in a state where the cable is assembled, the conductive member can be held smoothly.

[0021] Hereinafter, a power storage device according to an embodiment (including a modification thereof) of the present invention will be described with reference to the drawings. Each of the embodiments described below shows a comprehensive or specific example. The numerical values, shapes, materials, components, arrangement positions of the components, connection forms, etc. shown in the following embodiments are examples and are not intended to limit the present invention. In each figure, dimensions and the like are not strictly illustrated.

[0022] In the following description and drawings, the direction in which the electrode terminals of the energy storage elements in the energy storage device protrude is defined as the X-axis direction. The direction in which multiple energy storage elements are arranged, and the direction in which the first and second members forming the housing are arranged, are defined as the Y-axis direction. The direction in which the main body and outer cover of the energy storage device's casing are arranged, the direction in which the housing is inserted into or removed from the main body, or the vertical direction is defined as the Z-axis direction. These X-axis, Y-axis, and Z-axis directions intersect each other (orthogonal in the following embodiments and their modifications). In some usage scenarios, the Z-axis direction may not be vertical, but for the sake of explanation, the Z-axis direction will be described as vertical. In the following description, the X-axis positive direction refers to the direction of the arrow on the X-axis, and the X-axis negative direction refers to the opposite side from the X-axis positive direction. The same applies to the Y-axis and Z-axis directions. Furthermore, expressions indicating relative directions or orientations, such as parallel and orthogonal, may include cases where the direction or orientation is not strictly accurate. When two directions are orthogonal, it means not only that they are perfectly orthogonal, but also that they are substantially orthogonal, meaning they may have a difference of a few percent.

[0023] [General explanation of energy storage devices] A general description of the energy storage device 1 according to the embodiment will be given using Figures 1 and 2. Figure 1 is a perspective view showing the external appearance of the energy storage device 1 according to the embodiment. Figure 2 is an exploded perspective view showing the individual components when the energy storage device 1 according to the embodiment is disassembled.

[0024] The energy storage device 1 is a device that can charge electricity from an external source and discharge electricity to the outside, and in this embodiment, it has a substantially rectangular parallelepiped shape. The energy storage device 1 is a battery module (battery pack) used for power storage or power supply purposes. Specifically, 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, and railway vehicles for electric railways. Examples of automobiles include electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and gasoline automobiles. Examples of railway vehicles for electric railways include electric trains, monorails, and linear motor cars. The energy storage device 1 can also be used as a stationary battery for household use or for generators, etc.

[0025] As shown in Figures 1 and 2, the energy storage device 1 comprises an energy storage unit 20 and an outer casing 10 that houses the energy storage unit 20. The outer casing 10 has a main body 11 that houses the energy storage unit 20 and an outer cover 12 that covers the top of the energy storage unit 20.

[0026] The outer casing 10 is a rectangular (box-shaped) container (module case) that constitutes the outer casing of the energy storage device 1. In other words, the outer casing 10 is a component that fixes the energy storage unit 20 and other components in a predetermined position and protects these components from impacts and other damage.

[0027] The main body 11 is a bottomed rectangular cylindrical member with an open top, the open portion of which is an opening 111. The opening 111 is approximately rectangular in shape when viewed from above. The main body 11 has two first walls 112 on both sides in the X-axis direction, two second walls 113 on both sides in the Y-axis direction, and a third wall 114 on the negative Z-axis side. Specifically, the first walls 112 are rectangular and plate-shaped short side portions that form the short side of the main body 11. The second walls 113 are rectangular and plate-shaped long side portions that form the long side of the main body 11. The third wall 114 is a rectangular and plate-shaped bottom wall portion that forms the bottom surface of the main body 11.

[0028] In addition to the energy storage unit 20, the opening 111 of the main body 11 houses a plurality of busbars 33, fuses 34, and a control board 35, all of which are held by the energy storage unit 20.

[0029] The outer cover 12 is a member that closes the opening 111 of the main body 11 and is joined to the main body 11 in a state that covers the opening 111 of the main body 11. The outer cover 12 has a pair of external terminals 81 (positive side and negative side). The external terminals 81 are electrically connected to a plurality of energy storage elements 21 included in the energy storage unit 20 via each busbar 33, fuse 34 and control board 35. The energy storage device 1 charges with electricity from the outside and discharges electricity to the outside via these external terminals 81. The external terminals 81 are made of a conductive metal such as brass or copper alloy, copper, aluminum, or aluminum alloy.

[0030] Each busbar 33 is a plate-shaped member that electrically connects the external terminal 81 to the energy storage element 21. Each busbar 33 is made of a conductive metal such as copper, copper alloy, aluminum, or aluminum alloy.

[0031] The fuse 34 is a component that protects the control board 35 and multiple energy storage elements 21, etc., from high currents exceeding the rated value. The fuse 34 cuts off the flow of current by melting when a current exceeding the rated value flows through it.

[0032] The control board 35 has multiple electrical components, and these multiple electrical components form a detection circuit for detecting the state of each energy storage element 21, and a control circuit for controlling charging and discharging.

[0033] The main body 11 and outer cover 12 of the exterior body 10 are formed from insulating materials 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), polyetheretherketone (PEEK), tetrafluoroethylene perfluoroalkyl vinyl ether (PFA), polytetrafluoroethylene (PTFE), polyethersulfone (PES), ABS resin, or composite materials thereof, or from metal with an insulating coating. The exterior body 10 thereby prevents the energy storage element 21, etc. from coming into contact with external metal components. However, the exterior body 10 may be formed from a conductive material such as metal, as long as the electrical insulation of the energy storage element 21, etc. is maintained.

[0034] When the outer cover 12 is formed from resin, each external terminal 81 is integrated with the resin forming the outer cover 12 by insert molding. In other words, a portion of each external terminal 81 is directly in contact with the resin forming the outer cover 12 and is integrated while being covered by the resin. Specifically, the portion of the outer cover 12 that is in contact with each external terminal 81 is the fixing portion 121 that fixes each external terminal 81. External equipment is electrically connected to the portion of each external terminal 81 that protrudes and is exposed from the outer cover 12 in the positive Z-axis direction. In addition, a busbar 33 is joined to the portion of each external terminal 81 that is exposed from the outer cover 12 in the negative Z-axis direction. In this embodiment, the case in which the fixing portion 121 is formed by insert molding is illustrated, but any method of fixing the fixing portion 121 is acceptable as long as the external terminals 81 can be fixed to the outer cover 12. Fixing may be done by fitting, by fastening methods such as screws or rivets, by welding, or by adhesive.

[0035] [Energy storage unit] Figure 3 is an exploded perspective view showing the schematic configuration of an energy storage unit 20 according to an embodiment. As shown in Figure 3, the energy storage unit 20 comprises a plurality of energy storage elements 21 and a housing section 22 that houses these plurality of energy storage elements 21.

[0036] The energy storage element 21 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. In this embodiment, the energy storage element 21 is a pouch-type energy storage element having a flat shape, and a plurality of (four in this embodiment) pouch-type energy storage elements 21 are arranged in the Y-axis direction. The energy storage element 21 is not limited to a pouch-type energy storage element, but may also be an energy storage element with a flat rectangular parallelepiped shape (square), cylindrical shape, oblong cylindrical shape, or elliptical cylindrical shape, and its size and shape are not limited. The number of energy storage elements 21 arranged is also not particularly limited. The energy storage element 21 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 it may be a capacitor. The energy storage element 21 may not be a secondary battery, but a primary battery that can use the stored electricity without the user having to charge it.

[0037] Since all the energy storage elements 21 in the energy storage device 1 have the same configuration, the configuration of one energy storage element 21 will be described in detail below. Figure 3 shows all the energy storage elements 21 stacked on top of each other. The energy storage element 21 has a container 210 and a pair of electrode terminals 220 (positive electrode side and negative electrode side). Inside the container 210 are electrode bodies (not shown) and an electrolyte (non-aqueous electrolyte) (not shown). As for the electrolyte, there are no particular restrictions on its type as long as it does not impair the performance of the energy storage element 21, and any known material can be used as appropriate.

[0038] The container 210 is a sheet-like outer casing (outer film) made of laminate film, and it contains the electrode body and electrolyte, etc., sealed inside under reduced pressure. The container 210 is made up of two rectangular laminate films stacked in the Y-axis direction. The two laminate films are joined (sealed) by heat welding or the like, sandwiching a pair of electrode terminals 220. The laminate film is a flexible film consisting of multiple layers, including a metal layer such as aluminum and a resin layer such as polypropylene (PP) or polyethylene (PE), with the resin layer placed at the welded area (sealed part). The container 210 may also be made by forming a single laminate film into a bag shape and joining the ends of the laminate film together by heat welding. If the energy storage element 21 is not a pouch-type energy storage element, the container 210 may be made of a metal plate-like member such as stainless steel, aluminum, aluminum alloy, iron, or plated steel sheet.

[0039] The electrode terminals 220 are conductive plate-shaped members (lead plates) electrically connected to the electrode body, and are positioned exposed from the container 210 while penetrating the container 210. In this embodiment, a pair of electrode terminals 220 aligned in the Z-axis direction are positioned protruding in the X-axis negative direction from the X-axis negative end of the container 210. Specifically, the positive electrode terminal 220 is a lead terminal electrically connected to the positive electrode plate of the electrode body, and the negative electrode terminal 220 is a lead terminal electrically connected to the negative electrode plate of the electrode body. In other words, the electrode terminals 220 are metal electrode terminals for guiding the electricity stored in the electrode body to the external space of the energy storage element 21, and for introducing electricity into the internal space of the energy storage element 21 in order to store electricity in the electrode body. Note that one electrode terminal 220 (for example, the positive electrode side) may protrude from the X-axis positive end, and the other electrode terminal (for example, the negative electrode side) may protrude from the X-axis negative end. The electrode terminals 220 are made of aluminum, aluminum alloy, copper, copper alloy, etc.

[0040] In Figure 3, the electrode terminal 220 is shown in a simplified state, protruding only from the container 210 in the negative X-axis direction. However, the electrode terminal 220 may be extended and bent toward an adjacent energy storage element 21, and connected (joined) to the electrode terminal 220 of the adjacent energy storage element 21. Alternatively, the electrode terminal 220 may be connected (joined) to a conductive member such as a busbar, thereby electrically connecting to the electrode terminal 220 of the adjacent energy storage element 21. This allows multiple energy storage elements 21 to be connected in series or parallel. Furthermore, one of the pair of electrode terminals 220 of the end energy storage element 21 may be extended to an external terminal provided by the energy storage device 1 and connected (joined) to that external terminal, or it may be electrically connected to the external terminal by a conductive member such as a busbar, or the electrode terminal 220 itself may become an external terminal.

[0041] The electrode body is an energy storage element (power generation element) formed by laminating a positive electrode plate, a negative electrode plate, and a separator. The positive electrode plate has a positive electrode active material layer formed on a positive electrode base layer which is a current collector foil made of a metal such as aluminum or an aluminum alloy. The negative electrode plate has a negative electrode active material layer formed on a negative electrode base layer which is a current collector foil made of a metal such as copper or a copper alloy. As for the active material used in the positive electrode active material layer and the negative electrode active material layer, any known material can be used as long as it is capable of intercalating and releasing lithium ions. The separator can be a microporous sheet or nonwoven fabric made of resin. In this embodiment, the electrode body is formed by laminating electrode plates (positive electrode plate and negative electrode plate) in the Y-axis direction. The electrode body may be of any form, such as a wound electrode body formed by winding electrode plates (positive electrode plate and negative electrode plate), a laminated (stacked) electrode body formed by laminating a plurality of flat electrode plates, or a bellows-type electrode body in which the electrode plates are folded in a bellows shape.

[0042] The housing section 22 is a box-shaped (approximately rectangular parallelepiped) container (housing) that houses and holds a plurality of energy storage elements 21. The housing section 22 has a first member 23 and a second member 24 that is assembled to the first member 23 and houses the plurality of energy storage elements 21 together with the first member 23. The first member 23 and the second member 24 are positioned outside the plurality of energy storage elements 21, fixing the plurality of energy storage elements 21 in predetermined positions and protecting them from impacts, etc. The plurality of energy storage elements 21 are held by the first member 23 and the second member 24, thereby fixing the plurality of energy storage elements 21 inside the first member 23 and the second member 24. The first member 23 and the second member 24 are joined to each other by adhesive, heat sealing, ultrasonic welding, screw fastening, etc.

[0043] The first member 23 and the second member 24 are formed from insulating materials such as polycarbonate (PC), polypropylene (PP), polyethylene (PE), polyphenylene sulfide resin (PPS), polyphenylene ether (PPE (including modified PPE)), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyetherether ketone (PEEK), tetrafluoroethylene perfluoroalkyl vinyl ether (PFA), polytetrafluoroethylene (PTFE), polyethersulfone (PES), ABS resin, or composite materials thereof. As a result, the first member 23 and the second member 24 suppress electrical contact between the multiple energy storage elements 21 and conductive materials such as external metal members. However, if such contact is not necessary, the first member 23 and the second member 24 may be formed from conductive materials such as metal.

[0044] The first member 23 is a bottomed rectangular cylindrical housing positioned in the positive Y-axis direction of the second member 24, with the entire surface of the negative Y-axis direction open. The first member 23 has a pair of opposing first side walls 231 on both sides in the X-axis direction, a pair of opposing second side walls 232 on both sides in the Z-axis direction, and a bottom wall 233 on the positive Y-axis side.

[0045] The first side wall portion 231 is a flat, rectangular wall portion parallel to the YZ plane, forming the short side (short side wall) of the first member 23, and is positioned to sandwich the multiple energy storage elements 21 in the X-axis direction. The first side wall portion 231 is adjacent to the second side wall portion 232 and the bottom wall portion 233. The second side wall portion 232 is a flat, rectangular wall portion parallel to the XY plane, forming the long side (long side wall) of the first member 23, and is positioned to sandwich the multiple energy storage elements 21 in the Z-axis direction. The second side wall portion 232 is adjacent to the first side wall portion 231 and the bottom wall portion 233. The bottom wall portion 233 is a flat, rectangular wall portion parallel to the XZ plane, forming the bottom surface (bottom wall) of the first member 23, and faces and contacts the energy storage element 21 at the Y-axis positive end in the Y-axis direction.

[0046] Of the pair of first sidewall portions 231, the first sidewall portion 231 located in the negative X-axis direction has a notch 234 formed therein that exposes the electrode terminals 220 of multiple energy storage elements 21. A conductive path (not shown) is provided through this notch 234 to electrically connect the electrode terminals 220 of the energy storage elements 21 at the positive Y-axis end to an external terminal 81.

[0047] The second member 24 is a bottomed rectangular cylindrical housing positioned in the negative Y-axis direction of the first member 23, with the entire surface of the positive Y-axis direction open. The second member 24 has a pair of opposing first side walls 241 on both sides in the X-axis direction, a pair of opposing second side walls 242 on both sides in the Z-axis direction, and a bottom wall 243 on the negative Y-axis direction side.

[0048] The first side wall portion 241 is a flat, rectangular wall portion parallel to the YZ plane, forming the short side (short side wall) of the second member 24, and is positioned to sandwich multiple energy storage elements 21 in the X-axis direction. The first side wall portion 241 is adjacent to the second side wall portion 242 and the bottom wall portion 243. The second side wall portion 242 is a flat, rectangular wall portion parallel to the XY plane, forming the long side (long side wall) of the second member 24, and is positioned to sandwich multiple energy storage elements 21 in the Z-axis direction. The second side wall portion 242 is adjacent to the first side wall portion 241 and the bottom wall portion 243. The bottom wall portion 243 is a flat, rectangular wall portion parallel to the XZ plane, forming the bottom surface (bottom wall) of the second member 24, and faces and contacts the energy storage element 21 at the Y-axis negative end in the Y-axis direction.

[0049] The outer surface of the bottom wall portion 243 (the surface facing the negative Y-axis direction) is a mounting surface 25 to which multiple busbars 33, fuses 34, and a control board 35 are attached. The mounting surface 25 is provided with multiple boss portions 26 to which the control board 35 is screwed, a fuse mounting portion 27 to which the fuses 34 are attached, and multiple busbar mounting portions 28 to which each busbar 33 is individually attached.

[0050] Multiple boss portions 26 protrude from the mounting surface 25 in the negative Y-axis direction, and screw holes are formed in the center of their tip surfaces. The number of boss portions 26 can be any number, but in this embodiment, three boss portions 26 are provided, which are referred to as boss portions 26a, 26b, and 26c.

[0051] Boss portion 26a is located near the edge in the negative X-axis direction on the mounting surface 25 and approximately in the middle of the Z-axis direction. Boss portion 26b is located near the corner in the negative Z-axis direction on the mounting surface 25 and closer to the negative X-axis direction. Boss portion 26c is located near the positive X-axis direction on the mounting surface 25 and approximately in the middle of the Z-axis direction.

[0052] The fuse mounting portion 27 is positioned near the edge in the positive X-axis direction on the mounting surface 25, and a pair of them are arranged at a predetermined interval in the Z-axis direction. The fuse mounting portion 27 has a screw hole, and the fuse 34 is held in place by screwing a bolt that passes through the fuse 34 into this screw hole.

[0053] The multiple busbar mounting sections 28 are each parts that hold different busbars 33. The number of busbar mounting sections 28 can be any number, but in this embodiment, three busbar mounting sections 28 are provided, and they are referred to as busbar mounting sections 28a, 28b, and 28c.

[0054] The busbar mounting portion 28a is located near the edge in the negative X-axis direction on the mounting surface 25 and approximately in the center in the Z-axis direction. The busbar mounting portion 28a holds the busbar (not shown) which is joined (connected) to the electrode terminal 220 of the energy storage element 21 at its negative Y-axis end. The busbar mounting portion 28a has a screw hole, and the busbar is held by screwing a bolt that passes through the busbar into this screw hole.

[0055] The busbar mounting portion 28b is positioned on the mounting surface 25 closer to the positive X-axis direction and closer to the positive Z-axis direction. The busbar mounting portion 28b is joined (connected) to the external terminal 81 of the pair of external terminals 81 that is positioned in the positive X-axis direction, and also holds the busbar 33b that is joined (connected) to the fuse 34.

[0056] The busbar mounting portion 28c is positioned on the mounting surface 25 closer to the negative X-axis direction and closer to the positive Z-axis direction. The busbar mounting portion 28c holds the busbar 33c that is joined (connected) to the external terminal 81 of the pair of external terminals 81 that is positioned in the negative X-axis direction.

[0057] [External terminals, busbars, and busbar mounting sections] The external terminal 81, busbar 33c, and busbar mounting portion 28c, which are arranged in the negative X-axis direction, will be described in detail below with reference to Figures 4 to 6. Figure 4 is a perspective view showing the assembled state of the external terminal 81, busbar 33c, and busbar mounting portion 28c according to the embodiment. Figure 5 is a perspective view showing the busbar mounting portion 28c according to the embodiment. Figure 6 is a partial cross-sectional view showing the assembled state of the external terminal 81, busbar 33c, and busbar mounting portion 28c according to the embodiment. In Figures 4 and 5, the fixing portion 121 that fixes the external terminal 81 to the outer cover 12 is not shown.

[0058] As shown in Figures 4 to 6, the external terminal 81 is made of sheet metal and has an embedded portion 811 and an exposed portion 812. The embedded portion 811 is a flat plate-shaped part embedded in the fixing portion 121 (see Figure 2) in a position parallel to the XZ plane. The exposed portion 812 is a rectangular flat plate-shaped part that is bent from the upper end of the embedded portion 811 so as to be exposed from the fixing portion 121 and is parallel to the XY plane. A through hole 813 is formed in the exposed portion 812 with the Z axis direction as its axis.

[0059] The busbar 33c is made of sheet metal and has a first fastening portion 331 and a second fastening portion 332. The first fastening portion 331 has a rectangular flat plate portion 333 parallel to the XZ plane and a first bolt portion 334 protruding from the first plate portion 333 in the negative direction of the Y axis. The terminal 91 of the cable 90 (see Figure 2) extending from the control board 35 engages with the first bolt portion 334 and a nut 335 is fastened, thereby joining (connecting) the terminal 91 of the cable 90 to the first bolt portion 334.

[0060] The second fastening portion 332 has a rectangular flat plate portion 336 bent from the upper end of the first plate portion 333 and parallel to the XY plane, and a second bolt portion 337 protruding from the second plate portion 336 in the Z-axis positive direction. The exposed portion 812 of the external terminal 81 is joined (connected) to the second bolt portion 337 by fastening a nut 338 to the second bolt portion 337 while it is passing through the through hole 813 of the external terminal 81.

[0061] The busbar mounting portion 28c has a structure that allows the busbar 33c to slide freely relative to the external terminal 81 before the busbar 33c is fastened to the external terminal 81. In other words, the busbar mounting portion 28c is an example of a holding portion that holds the busbar 33c. Specifically, the busbar mounting portion 28c has a base portion 281 and a pair of ribs 282.

[0062] The base portion 281 is the part that supports the first fastening portion 331 of the bus bar 33c, and comprises a wall body 285, a pair of upper contact portions 283, and a pair of lower contact portions 284. The wall body 285 is a wall formed in a substantially U-shape with the top open in a plan view (view in the Y-axis direction), and is erected from the mounting surface 25. In the wall body 285, the distance X1 between the portions on both sides in the X-axis direction is greater than the width X2 in the X-axis direction of the first plate portion 333 of the first fastening portion 331 (see Figure 6).

[0063] The pair of upper contact portions 283 are parts that protrude inward from the pair of upper ends of the wall body 285, and contact the main surface of the first plate portion 333 of the first fastening portion 331 in the negative Y-axis direction, thereby restricting the movement of the first plate portion 333 in the negative Y-axis direction.

[0064] The pair of lower contact portions 284 are parts that protrude inward from a pair of corners at the lower end of the wall body 285, and contact the main surface of the first plate portion 333 of the first fastening portion 331 in the negative Y-axis direction, thereby restricting the movement of the first plate portion 333 in the negative Y-axis direction.

[0065] The pair of ribs 282 are erected from the mounting surface 25 in the negative Y-axis direction and extend in the Z-axis direction. The pair of ribs 282 are arranged at a predetermined distance in the X-axis direction. The upper end of each rib 282 is an inclined surface 282a, which gradually decreases in height (length in the Y-axis direction) as it moves upward. In addition, the portion of each rib 282 in the negative Z-axis direction relative to the inclined surface 282a is a flat surface 282b with a constant height. The distance between the flat surface 282b and each lower contact portion 284 is the length into which the first plate portion 333 of the first fastening portion 331 fits. On the other hand, the distance between each upper contact portion 283 and the inclined surface 282a gradually increases as it moves upward. Therefore, when the first plate portion 333 is inserted into the base portion 281 from above, the lower end of the first plate portion 333 first smoothly fits into the distance between each upper contact portion 283 and the inclined surface 282a. Subsequently, the lower end of the first plate portion 333 is gradually pressed against each upper contact portion 283 by the inclined surface 282a, reaching the flat surface 282b, and sliding on the flat surface 282b. Next, when the lower end of the first plate portion 333 reaches each lower contact portion 284, it is fitted in a state where it is sandwiched between each lower contact portion 284 and the flat surface 282b. During this fitting, the movement of the first plate portion 333 in the Y-axis direction is restricted by being sandwiched between each upper contact portion 283, each lower contact portion 284 and the flat surface 282b, but the movement of the first plate portion 333 in the Z-axis direction is not restricted. In this way, the busbar mounting portion 28c holds the busbar 33c so that it can slide freely in the Z-axis direction. More specifically, the busbar mounting portion 28c allows the busbar 33c to slide toward the nut 338 (in the positive Z-axis direction) when the busbar 33c is fastened to the external terminal 81 by the nut 338, which is a fastening member.

[0066] As described above, in the wall 285 of the base portion 281, the distance X1 between the portions on both sides in the X-axis direction is greater than the width X2 of the first plate portion 333. For this reason, it can be said that the bus bar 33c is held to slide freely in the X-axis direction by the difference between the distance X1 and the width X2. Furthermore, this difference also allows rotation of the bus bar 33c (rotation direction C1) with the Y-axis direction as the center of rotation. The center of rotation in rotation direction C1 can be said to be in a direction that intersects the sliding direction of the bus bar 33c (Z-axis direction or X-axis direction).

[0067] [External terminals, connection operation between busbars and external terminals] The fastening operation between the busbar 33c and the external terminal 81 will be described.

[0068] As described above, before fastening, the busbar 33c is held by the busbar mounting portion 28c. In this state, the second plate portion 336 of the busbar 33c and the exposed portion 812 of the external terminal 81 are superimposed, and the second bolt portion 337 of the busbar 33c passes through the through hole 813 of the exposed portion 812. At this time, the terminal 91 of the cable 90 is fastened to the first bolt portion 334 of the busbar 33c, but the busbar 33c may move in the Z-axis direction, move in the X-axis direction, or rotate in the rotational direction C1 due to a load caused by deformation of the cable 90. In this case, since these movements are permitted by the busbar mounting portion 28c, the busbar 33c can be held smoothly even with the cable 90 assembled to it.

[0069] Subsequently, when the nut 338 is fastened to the second bolt portion 337, the fastening force pulls the busbar 33c in the fastening direction (positive Z-axis direction). Since movement in the Z-axis direction is permitted at the busbar mounting portion 28c, the busbar 33c slides in the positive Z-axis direction and contacts the exposed portion 812 of the external terminal 81, and is fastened. In this way, the busbar 33c slides during fastening, which alleviates stress concentration on the busbar 33c.

[0070] Before fastening, even if the busbar 33c is deformed from its normal position due to the deformation of the cable 90, movement in the Z-axis and X-axis directions, as well as rotation, are still permitted. Therefore, upon fastening, the busbar 33c rotates and adjusts its position while sliding in the Z-axis and X-axis directions, ultimately arriving at its normal position (see Figure 6).

[0071] [Effects, etc.] As described above, according to this embodiment, the external terminal 81 is fixed by the fixing part 121, and the bus bar 33c in its pre-fastening state is slidably held relative to the external terminal 81 by the bus bar mounting part 28c. Therefore, when the external terminal 81 and the bus bar 33c are fastened together, the bus bar 33c slides due to the fastening force. This reduces stress concentration on the bus bar 33c and suppresses damage to the bus bar 33c. Consequently, a decrease in the reliability of the energy storage device 1 can be suppressed.

[0072] Since the busbar 33c is fitted into the busbar mounting portion 28c, the movement of the busbar 33c can be restricted to some extent before fastening. Therefore, the stability of the fastening process can be improved. If the stability of the fastening process is improved, the decrease in the reliability of the energy storage device 1 can be further suppressed.

[0073] Since the busbar mounting portion 28c allows the busbar 33c to rotate, the busbar 33c can rotate in addition to sliding when fastened. This increases the degree of freedom of movement of the busbar 33c when fastened. As a result, stress concentration on the busbar 33c can be further reduced, and damage to the busbar 33c can be more reliably suppressed. Therefore, the decrease in the reliability of the energy storage device 1 can be further suppressed.

[0074] Since the sliding direction of the busbar 33c at the busbar mounting portion 28c and the fastening direction (Z-axis direction) during fastening are aligned with each other, the busbar 33c can slide smoothly during fastening. This further reduces stress concentration on the busbar 33c and more reliably suppresses damage to the busbar 33c. Therefore, the decrease in reliability of the energy storage device 1 can be further suppressed.

[0075] The busbar mounting portion 28c allows the busbar 33c to slide toward the nut 338 when the busbar 33c is fastened to the external terminal 81, so that the busbar 33c moves toward the nut 338 when fastened. In other words, the busbar 33c can be actively moved by fastening, so stress concentration on the busbar 33c can be further reduced. Therefore, the decrease in reliability of the energy storage device 1 can be further suppressed.

[0076] Since the busbar 33c, to which the cable 90 is attached, is held slidably by the busbar mounting portion 28c, it is possible to hold the busbar 33c while allowing it to slide, even when it is prone to movement due to the deformation of the cable 90. Therefore, the busbar 33c can be held smoothly even when the cable 90 is attached.

[0077] [Example 1] In the above embodiment, an example was given in which the external terminal 81 (terminal) is fixed to the fixing part 121 and the busbar 33c (conductive member) is slidably held in the holding part (busbar mounting part 28c). However, the conductive member may be fixed and the terminal may be slidably held.

[0078] Figure 7 is a partial cross-sectional view showing the assembled state of the external terminal 81d, busbar 33d, and retaining part 60d according to a modified example.

[0079] The external terminal 81d is formed from sheet metal and has a first flat plate portion 815d parallel to the XY plane and a second flat plate portion 816d that is bent upward from the Y-axis positive end of the first flat plate portion 815d and is parallel to the XZ plane. A through hole 817d is formed in the first flat plate portion 815d with the Z-axis direction as its axial direction.

[0080] The busbar 33d has a flat plate portion 37d and a bolt portion 38d that protrudes in the positive Z-axis direction from a part of the flat plate portion 37d. The flat plate portion 37d is integrated with the resin forming the outer casing or housing by insert molding. In other words, a part of the busbar 33d is directly in contact with the resin forming the outer casing or housing, and is integrated while being covered by the resin. Specifically, the part of the outer casing or housing that is in contact with the busbar 33d is the fixing portion 39d that secures the busbar 33d.

[0081] The holding portion 60d has a structure that allows the external terminal 81d to slide freely relative to the bus bar 33d before the external terminal 81d is fastened to the bus bar 33d. Specifically, the holding portion 60d has a pair of clamping portions 61d that are erected from the mounting surface 25d of the outer casing or housing portion. The pair of clamping portions 61d are arranged to clamp the bus bar 33d in the X-axis direction. Each clamping portion 61d extends in the Z-axis direction, and its upper end is provided with a contact portion 283d that protrudes inward. Each contact portion 283d contacts the second flat plate portion 816d of the external terminal 81d. The second flat plate portion 816d is fitted while being clamped between each contact portion 283d and the mounting surface 25d. During this mating process, the second flat plate portion 816d is merely sandwiched between the contact portions 283d and the mounting surface 25d, and the movement of the external terminal 81d in the Z-axis direction is not restricted.

[0082] The fastening operation between the bus bar 33d and the external terminal 81d will now be described. Before fastening, the external terminal 81d is held by the retaining portion 60d. In this state, the bolt portion 38d of the bus bar 33d passes through the through hole 817d of the external terminal 81d. At this time, the first flat plate portion 815d of the external terminal 81d is held by the retaining portion 60d, separated from the flat plate portion 37d of the bus bar 33d.

[0083] Subsequently, when fastening the nut 338d to the bolt portion 38d, the external terminal 81d slides in the negative Z-axis direction because its movement in the Z-axis direction is permitted by the holding portion 60d. As a result, the first flat plate portion 815d of the external terminal 81d overlaps with the flat plate portion 37d of the busbar 33d and is fastened. Because the external terminal 81d slides during fastening in this way, stress concentration on the external terminal 81d is alleviated.

[0084] [others] Although an energy storage device according to an embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment. In other words, the embodiments disclosed herein are illustrative and not restrictive in all respects. The scope of the present invention is indicated by the claims, and all modifications within the meaning and scope of equivalents of the claims are included.

[0085] In the embodiment, the busbar mounting portion 28c, which is the holding portion, is shown as allowing the busbar 33c to slide and rotate in the Z-axis and X-axis directions. However, the holding portion may also allow the busbar to slide in only one direction. In this case, it is preferable that the holding portion allows the busbar to slide in the direction along the fastening direction.

[0086] In this embodiment, the busbar mounting portion 28c is exemplified as the holding portion, but the structure of the holding portion can be anything as long as it can slidably hold the conductive member relative to the terminal before the conductive member is fastened to the terminal. Similarly, in Modification 1, the holding portion 60d is exemplified as the holding portion, but the structure of the holding portion can be anything as long as it can slidably hold the terminal relative to the conductive member before the conductive member is fastened to the terminal.

[0087] In this embodiment, we have illustrated a case where only the busbar mounting portion 28c slidably holds the busbar 33c, but other busbar mounting portions may also slidably hold the busbar.

[0088] In the embodiment, a busbar 33c was exemplified as the conductive member according to the present invention, but the conductive member can also include cables, fuses, and the like. In the embodiment, an external terminal 81 was exemplified as the terminal according to the present invention, but the terminal can also include internal terminals and the like.

[0089] In this embodiment, the fixing portion 121 is shown as being provided on the outer cover 12 of the exterior body 10, but the fixing portion may be provided on the main body of the exterior body, or on a component other than the exterior body that constitutes the energy storage device. Similarly, in this embodiment, the busbar mounting portion 28c, which is a holding portion, is shown as being provided on the housing portion 22, but the holding portion may be provided on a component other than the housing portion 22 that constitutes the energy storage device. In this embodiment, the fixing portion and the holding portion are shown as being provided on separate components, but the fixing portion and the holding portion may be provided on a single component.

[0090] The present invention also includes forms constructed by arbitrarily combining the components included in the embodiments and their modified examples. [Industrial applicability]

[0091] This invention can be applied to energy storage devices equipped with energy storage elements such as lithium-ion secondary batteries. [Explanation of symbols]

[0092] 1. Energy storage device 10 Exterior 11 Main body 12 Outer lid 20 Energy storage units 21 Energy storage element 22 Storage Unit 23 First component 24 Second component 25, 25d mounting surface 26, 26a, 26b, 26c Boss section 27 Fuse mounting section 28, 28a, 28b Busbar mounting section 28c Busbar mounting section (retaining section) 33, 33b, 33c, 33d Busbars (conductive members) 34 fuses 35 Control board 37d Flat plate part 38d Bolt section 39d, 121 fixed part 60d holding part 61d Clamping part 81, 81d External terminals (terminals) 90 Cable 91 terminals 111 Opening 112 First wall 113 Second wall 114 Third wall 210 Container 220 Electrode terminal 231, 241 First side wall part 232, 242 Second side wall part 233, 243 Bottom wall section 234 Notch 281 Base 282 Rib 282a Slope 282b flat surface 283 Upper contact part 283d Contact part 284 Lower contact part 285 Wall 331 First fastening part 332 Second fastening part 333 First plate part 334 First bolt section 335, 338, 338d nuts 336 Second plate part 337 Second bolt section 811 Buried section 812 Exposed part 813, 817d through hole 815d First Flat Plate Section 816d Second Flat Plate Section

Claims

1. A power storage device having a power storage element, Terminals and A conductive member that is electrically connected to the energy storage element and fastened to the terminal, A fixing part for fixing the terminals to a predetermined position in the energy storage device, The system includes a holding portion for holding the conductive member, The aforementioned retaining part is A pair of walls that sandwich the conductive member with a width greater than the width of the conductive member, Each of the pair of walls has a contact portion that protrudes inward from the pair of walls and contacts the conductive member, The pair of walls and the contact portion allow the conductive member to slide freely relative to the terminal before the conductive member is fastened to the terminal, and also allow the conductive member to rotate around a direction intersecting the sliding direction of the conductive member. Energy storage device.

2. The retaining portion has a structure into which the conductive member is fitted. The energy storage device according to claim 1.

3. The sliding direction of the conductive member in the holding portion is in the direction of fastening during fastening. The energy storage device according to claim 1 or 2.

4. The fastening member for fastening the conductive member is provided, The fastening member allows the conductive member to slide toward the fastening member when it is fastened to the terminal by the fastening member. The energy storage device according to claim 3.

5. The conductive member is fitted with a cable that is electrically connected to the energy storage element. The energy storage device according to any one of claims 1 to 4.

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