WO2024166735A1

WO2024166735A1 - Power storage device

Info

Publication number: WO2024166735A1
Application number: PCT/JP2024/002727
Authority: WO
Inventors: 尚之北村; 寿樹楠
Original assignee: 株式会社Ｇｓユアサ
Priority date: 2023-02-06
Filing date: 2024-01-30
Publication date: 2024-08-15

Abstract

This power storage device comprises: a power storage element; a case that accommodates therein the power storage element; and an external terminal disposed at the case. The external terminal has a first member having electrical conductivity and penetrating through the case, and a second member protruding farther outward of the case as compared to the first member. The tensile strength of the second member is greater than the tensile strength of the first member.

Description

Power storage device

The present invention relates to an electricity storage device.

　Conventionally, power storage devices in which external terminals are arranged on a case that houses a power storage element are widely known. For example, Patent Document 1 discloses a battery pack that includes a pack case, a plurality of battery cells housed within the pack case, a pack cover that covers the pack case, and terminals that penetrate to the outside of the pack cover and are connected to an external power source.

Special table 2018-521468 publication

In the above-mentioned conventional energy storage device, an external conductive member (such as a bus bar) is joined to the external terminal, but if a load such as a tensile load or a torsional load is applied to the external terminal during joining, there is a risk that the external terminal may be damaged (broken, etc.).

The present invention was made by the inventors by focusing on the above problem, and aims to provide an electricity storage device that can suppress damage to the external terminals.

The energy storage device according to one aspect of the present invention comprises an energy storage element, a case that houses the energy storage element, and an external terminal disposed in the case, the external terminal having a conductive first member that penetrates the case and a second member that protrudes outward from the case beyond the first member, and the tensile strength of the second member is higher than the tensile strength of the first member.

The power storage device of the present invention can reduce damage to the external terminals.

FIG. 1 is a perspective view showing the appearance of a power storage device according to an embodiment. FIG. 2 is an exploded perspective view showing each component of the electricity storage device according to the embodiment. FIG. 3 is a perspective view showing a configuration of an energy storage element according to an embodiment. FIG. 4 is a cross-sectional view showing a configuration of an external terminal according to the embodiment. FIG. 5 is a cross-sectional view showing a configuration of an external terminal according to the first modification of the embodiment. FIG. 6 is a cross-sectional view showing a configuration of an external terminal according to the second modification of the embodiment. FIG. 7 is a cross-sectional view showing a configuration of an external terminal according to a third modification of the embodiment.

(1) An energy storage device according to one aspect of the present invention includes an energy storage element, a case that houses the energy storage element, and an external terminal disposed in the case, the external terminal having a conductive first member that penetrates the case and a second member that protrudes outward from the case beyond the first member, and the tensile strength of the second member is higher than the tensile strength of the first member.

According to this, in the energy storage device, the external terminal is configured to be divided into a conductive first member that penetrates the case and a second member that protrudes outside the case beyond the first member, and the tensile strength of the second member is made higher than that of the first member. As a result, in the external terminal, the first member can electrically connect the conductive members (bus bars, etc.) inside and outside the case, and the second member can be used to join the external terminal and the external conductive member. Because the tensile strength of the second member is higher than that of the first member, damage (breakage, etc.) to the second member can be suppressed even if a load such as a tensile load or a torsional load is applied to the second member when joining the external terminal and the external conductive member. Therefore, damage to the external terminal can be suppressed in the energy storage device.

(2) In the energy storage device described in (1) above, the volume resistivity of the first member may be lower than the volume resistivity of the second member.

By reducing the volume resistivity of the first member in the external terminal, electricity can flow through the first member (external terminal) with low resistance.

(3) In the energy storage device described in (1) or (2) above, the second member may have an inner portion disposed within a portion of the first member that penetrates the case, and a protruding portion that protrudes from the inner portion to the outside of the case.

According to this, in the external terminal, the second member is configured so that the protruding portion protrudes outward from the case from the inside portion of the portion of the first member that penetrates the case. This makes it easy to position the second member relative to the first member, and also prevents the protruding portion of the second member from protruding too far from the case.

(4) In the energy storage device described in any one of (1) to (3) above, the second member may penetrate the first member.

In this way, by configuring the external terminal so that the second member penetrates the first member, the second member can be easily positioned relative to the first member.

(5) In the energy storage device described in any one of (1) to (4) above, the second member may have a male thread portion, and the first member may have a female thread portion that is coupled to the male thread portion.

In this way, by connecting the first member and the second member with a screw in the external terminal, the second member can be firmly fixed to the first member.

(6) In the energy storage device described in any one of (1) to (5) above, the second member may have an inner portion disposed within the first member and a protruding portion protruding from the inner portion to the outside of the case, and the cross-sectional area of a surface of the inner portion perpendicular to the protruding direction of the protruding portion may be larger than the cross-sectional area of a surface of the protruding portion perpendicular to the protruding direction.

In this way, by increasing the cross-sectional area of the inner part of the second member in the external terminal, the inner part can withstand a large torque from the outside. By reducing the cross-sectional area of the protruding part of the second member, even if the cross-sectional area of the inner part is large, the protruding part can be formed to a size suitable for fixing the external terminal to an external conductive member.

Below, with reference to the drawings, an explanation will be given of an energy storage device according to an embodiment of the present invention (including its modified examples). The embodiments explained below are all comprehensive or specific examples. The numerical values, shapes, materials, components, the arrangement and connection of the components, manufacturing processes, and the order of the manufacturing processes shown in the following embodiments are merely examples and are not intended to limit the present invention. In each figure, dimensions are not strictly illustrated. In each figure, the same or similar components are given the same reference numerals.

In the following description and drawings, the X-axis direction is defined as the arrangement direction of multiple energy storage elements, or the direction in which the long sides of the container of one energy storage element face each other. The Y-axis direction is defined as the arrangement direction of a pair of terminals (positive and negative) in one energy storage element, or the direction in which the short sides of the container of one energy storage element face each other. The Z-axis direction is defined as the arrangement direction of the main body and lid of the exterior body of the energy storage device, the arrangement direction of the main body and lid of the container of the energy storage element, the protruding direction of the external terminals, or the up-down direction. The X-axis, Y-axis, and Z-axis directions intersect with each other (orthogonal in this embodiment). Depending on the mode of use, the Z-axis direction may not be the up-down direction, but for ease of explanation, the following description will be given assuming that the Z-axis direction is the up-down direction.

In the following explanation, the positive X-axis direction refers to the direction of the X-axis arrow, and the negative X-axis direction refers to the direction opposite to the positive X-axis direction. When simply referring to the X-axis direction, it refers to both or either of the positive and negative X-axis directions. The same applies to the Y-axis and Z-axis directions. Expressions indicating relative directions or attitudes, such as parallel and perpendicular, also include cases where the direction or attitude is not strictly speaking the same. Two directions being parallel does not only mean that the two directions are completely parallel, but also means that they are substantially parallel, that is, that there is a difference of, for example, about a few percent. In the following explanation, when the word "insulation" is used, it means "electrical insulation".

(Embodiment)
[1 General Description of Power Storage Device 10]
First, a general description of a power storage device 10 according to the present embodiment will be given. Fig. 1 is a perspective view showing the external appearance of the power storage device 10 according to the present embodiment. Fig. 2 is an exploded perspective view showing each component of the power storage device 10 according to the present embodiment when disassembled.

The power storage device 10 is a device that can charge electricity from the outside and discharge electricity to the outside, and in this embodiment, has a substantially rectangular parallelepiped shape. A rectangular parallelepiped is a hexahedron with all sides formed of rectangles or squares. The power storage device 10 is a battery module (battery assembly) used for power storage or power supply purposes. Specifically, the power storage device 10 is used as a battery for driving or starting the engine of a moving body such as an automobile, a motorcycle, a watercraft, a ship, a snowmobile, an agricultural machine, a construction machine, an automatic guided vehicle (AGV), or a railway vehicle for an electric railway. Examples of the above-mentioned automobiles 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 an electric railway include electric trains, monorails, linear motor cars, and hybrid electric trains equipped with both a diesel engine and an electric motor. The energy storage device 10 can also be used as a stationary battery for home or business use.

As shown in FIG. 1, the energy storage device 10 includes a case 100 and a pair of external terminals 200 (positive and negative). As shown in FIG. 2, a plurality of energy storage elements 300 and a bus bar 400 are housed inside the case 100. In addition to the above components, the energy storage device 10 may include spacers arranged between the plurality of energy storage elements 300, restraining members (side plates, end plates, etc.) that restrain the plurality of energy storage elements 300, a bus bar holder that holds the bus bar 400, a circuit board that monitors or controls the charge and discharge states of the energy storage elements 300, electrical components such as relays, fuses, shunt resistors, and connectors, and an exhaust section for exhausting gas discharged from the energy storage elements 300 to the outside of the case 100.

The case 100 is a roughly rectangular parallelepiped (box-shaped) container (module case) that constitutes the exterior body (housing, outer shell) of the energy storage device 10. The case 100 is disposed outside the multiple energy storage elements 300 and bus bars 400, etc., and fixes the energy storage elements 300, etc. in a predetermined position to protect them from impacts, etc. The case 100 is formed from an insulating material such as polycarbonate (PC), polypropylene (PP), polyethylene (PE), polystyrene (PS), polyphenylene sulfide resin (PPS), polyphenylene ether (PPE (including modified PPE)), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyether ether ketone (PEEK), tetrafluoroethylene perfluoroalkyl vinyl ether (PFA), polytetrafluoroethylene (PTFE), polyether sulfone (PES), polyamide (PA), ABS resin, or a composite material thereof, or a metal with an insulating coating. This prevents the energy storage element 300 and other components from coming into contact with external metal components. The case 100 may be made of a conductive material such as metal as long as the insulation properties of the energy storage element 300 and other components are maintained.

The case 100 has a case body 110 constituting the body of the case 100, and a case lid 120 constituting the lid of the case 100. The case body 110 and the case lid 120 may be made of the same material or different materials. The case body 110 is a bottomed rectangular cylindrical housing (chassis) with an opening in the positive Z-axis direction, and contains the energy storage element 300 and the like. The case body 110 has a pair of flat and rectangular long side walls on both sides in the Y-axis direction, a pair of flat and rectangular short side walls on both sides in the X-axis direction, and a flat and rectangular bottom wall in the negative Z-axis direction. Depending on the configuration of the contents of the case body 110, the long side walls, short side walls, and bottom wall may have any shape. The case lid 120 is a flat rectangular member that closes the opening of the case body 110. The case lid 120 has a wall portion 121 on which a pair of external terminals 200 are arranged. The case lid 120 is joined to the case body 110 by adhesive, heat sealing, ultrasonic welding, or screwing with bolts. This results in the case 100 having a structure in which the inside is sealed (sealed).

The external terminals 200 are external terminals (positive and negative external terminals) for electrically connecting the storage device 10 to a device external thereto. In this embodiment, the external terminal 200 in the positive direction of the X-axis is the positive external terminal, and the external terminal 200 in the negative direction of the X-axis is the negative external terminal. The external terminals 200 are disposed (fixed) on the wall 121 of the case cover 120 while penetrating the wall 121 and protruding outward from the wall 121. The storage device 10 charges with electricity from the outside and discharges electricity to the outside through the pair of external terminals 200 (positive and negative). In this embodiment, the positive external terminal 200 and the negative external terminal 200 have the same configuration. A detailed description of the configuration of the external terminals 200 will be given later.

The storage element 300 is a secondary battery (single cell) that can charge and discharge electricity, and more specifically, is a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery. The storage element 300 has a flattened rectangular parallelepiped shape (rectangular, box-shaped) in the X-axis direction, and in this embodiment, eight storage elements 300 are arranged in the X-axis direction. The size, shape, and number of storage elements 300 arranged are not limited, and the storage element 300 may be, for example, a cylindrical shape (cylinder shape), an elongated cylindrical shape, an elliptical cylindrical shape, a polygonal prism shape other than a rectangular parallelepiped, or the like, or only one storage element 300 may be arranged. The storage element 300 is not limited to a non-aqueous electrolyte secondary battery, and may be a secondary battery other than a non-aqueous electrolyte secondary battery, or may be a capacitor. The storage element 300 may be a primary battery instead of a secondary battery. The storage element 300 may be a battery using a solid electrolyte. The energy storage element 300 may be a pouch-type energy storage element. A detailed description of the configuration of the energy storage element 300 will be provided later.

The bus bar 400 is a plate-like member connected to the energy storage elements 300 and the external terminal 200. The bus bar 400 is disposed above the energy storage elements 300, and is connected (joined) to the terminals 340 of the energy storage elements 300 and the external terminal 200. Specifically, the bus bar 400 connects the terminals 340 of the energy storage elements 300 to each other, and also connects the terminals 340 of the end energy storage elements 300 to the external terminal 200. The bus bar 400 is formed of a conductive member made of metal such as aluminum, aluminum alloy, copper, copper alloy, nickel, etc., or a combination of these, or a conductive member other than metal.

The busbar 400 has a busbar 410, a busbar 420, three busbars 430, and two busbars 440 (see FIG. 4). The busbar 430 connects two energy storage elements 300 in parallel to form four sets of energy storage element groups, and connects the four sets of energy storage element groups in series. The busbar 410 is connected to the positive terminals of two energy storage elements 300 in the energy storage element group arranged near the positive external terminal 200 (the end in the positive direction of the X-axis), and is connected to the positive external terminal 200 via the positive busbar 440. In other words, the busbar 410 is connected to the positive terminal of the energy storage element 300, and the busbar 440 is connected to the positive external terminal 200 (see FIG. 4), and the busbar 410 and the busbar 440 are connected. The bus bar 420 is connected to the negative terminals of two energy storage elements 300 in the energy storage element group arranged near the negative external terminal 200 (the end in the negative direction of the X-axis), and is also connected to the negative external terminal 200 via the negative bus bar 440. In other words, the bus bar 420 is connected to the negative terminal of the energy storage element 300, and the bus bar 440 is connected to the negative external terminal 200 (see FIG. 4), and the bus bar 420 and the bus bar 440 are connected.

The connection form of the

busbars

410, 420, and 430 is not particularly limited, and the multiple energy storage elements 300 may be connected in series or in parallel in any combination, or all of the energy storage elements 300 may be connected in series or in parallel. In this embodiment, the

busbars

410, 420, or 430 are joined to the terminals 340 by welding, but the terminals 340 may be bolt terminals having bolt portions (male thread portions) and may be bolted to the terminals 340, or they may be joined by other methods. The

busbars

410 or 420 and the busbars 440 are joined by bolting, but they may also be joined by welding or other methods.

[2. Description of Energy Storage Element 300]
Next, the configuration of the energy storage element 300 will be described in detail. Fig. 3 is a perspective view showing the configuration of the energy storage element 300 according to the present embodiment. Fig. 3 shows an enlarged external view of one of the plurality of energy storage elements 300 shown in Fig. 2. Since the plurality of energy storage elements 300 all have the same configuration, Fig. 3 shows one energy storage element 300, and the configuration of one energy storage element 300 will be described in detail below.

As shown in FIG. 3, the energy storage element 300 has an element container 310, a pair of terminals 340 (positive and negative electrodes), and a pair of gaskets (insulating members) 350 (positive and negative electrodes). Inside the element container 310, an electrode body, a pair of current collectors (positive and negative electrodes), and an electrolyte (non-aqueous electrolyte) are contained, but these are not shown. There is no particular limit to the type of electrolyte as long as it does not impair the performance of the energy storage element 300, and various electrolytes can be selected. In addition to the above components, the energy storage element 300 may have spacers arranged on the sides or below the electrode body, an insulating film that encases the electrode body, or an insulating film (shrink tube, etc.) that covers the outer surface of the element container 310.

The element container 310 is a rectangular parallelepiped (angular or box-shaped) container having a container body 320 with an opening and a container lid 330 that closes the opening of the container body 320. The container body 320 is a rectangular cylindrical member with a bottom that constitutes the main body of the element container 310, and has an opening on the Z-axis positive side. The container lid 330 is a rectangular plate-shaped member that is long in the Y-axis direction and constitutes the lid of the element container 310, and is arranged in the Z-axis positive direction of the container body 320. The container lid 330 is provided with a gas exhaust valve 331 that releases pressure when the pressure inside the element container 310 rises excessively, and a liquid injection part (not shown) for injecting electrolyte into the element container 310, etc. The element container 310 is structured so that the inside is sealed (sealed) by joining the container body 320 and the container lid 330 by welding or the like after the electrode body and the like are accommodated inside the container body 320. The material of the element container 310 (container body 320 and container lid 330) is not particularly limited, and can be a weldable (joinable) metal such as stainless steel, aluminum, aluminum alloy, iron, or plated steel sheet, but resin can also be used. The element container 310 has a pair of long sides on both sides in the X-axis direction, a pair of short sides on both sides in the Y-axis direction, and a bottom surface on the negative Z-axis side.

The terminals 340 are electrode terminals (positive and negative terminals) of the energy storage element 300 that are arranged on the container lid 330. Specifically, the terminals 340 are arranged protruding from the upper surface (terminal arrangement surface) of the container lid 330 in the positive direction of the Z axis. The terminals 340 are electrically connected to the positive and negative plates of the electrode body via a current collector. In other words, the terminals 340 are metal members that conduct electricity stored in the electrode body to the external space of the energy storage element 300 and introduce electricity into the internal space of the energy storage element 300 to store electricity in the electrode body. The terminals 340 are formed of aluminum, an aluminum alloy, copper, a copper alloy, or the like.

The electrode body is a storage element (power generating element) formed by stacking a positive electrode plate, a negative electrode plate, and a separator. The positive electrode plate is a current collector foil made of a metal such as aluminum or an aluminum alloy, on which a positive electrode active material layer is formed. The negative electrode plate is a current collector foil made of a metal such as copper or a copper alloy, on which a negative electrode active material layer is formed. As 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 can absorb and release lithium ions. The separator can be a microporous sheet or nonwoven fabric made of resin. In this embodiment, the electrode body is formed by stacking the electrode plates (positive electrode plate and negative electrode plate) in the X-axis direction. The electrode body may be of any shape, such as a wound type electrode body formed by winding the electrode plates (positive electrode plate and negative electrode plate), a stack type electrode body formed by stacking multiple flat electrode plates, or a bellows type electrode body in which the electrode plates are folded in a bellows shape.

The current collectors are conductive current collecting members (positive and negative current collectors) electrically connected to the terminal 340 and the electrode body. The positive current collector is made of aluminum or an aluminum alloy, etc., like the current collecting foil of the positive plate of the electrode body, and the negative current collector is made of copper or a copper alloy, etc., like the current collecting foil of the negative plate of the electrode body. The gasket 350 is disposed between the container lid 330 and the terminal 340 and the current collector, and is a gasket that provides insulation between the container lid 330 and the terminal 340 and the current collector. The gasket 350 may be made of any material as long as it has insulating properties.

[3. Description of External Terminal 200]
Next, the configuration of the external terminal 200 will be described in detail. FIG. 4 is a cross-sectional view showing the configuration of the external terminal 200 according to this embodiment. FIG. 4 is a cross-sectional view showing the configuration of the external terminal 200 of the power storage device 10 shown in FIG. 1 and its surroundings when cut in an XZ plane passing through line IV-IV. In FIG. 4, for convenience of explanation, the bus bar 20, which is a conductive member connected to the external terminal 200 outside the power storage device 10, is shown by a two-dot chain line. Since a pair of external terminals 200 (positive and negative electrodes) provided in the power storage device 10 have the same configuration, FIG. 4 shows the configuration of one external terminal 200 and its surroundings.

As shown in FIG. 4, the external terminal 200 has a first member 210, a second member 220, and a connecting member 230.

The first member 210 is a conductive member that penetrates the case 100. In this embodiment, the first member 210 penetrates the wall portion 121 of the case cover body 120 in the Z-axis direction. Specifically, the first member 210 is an annular or tubular member (in this embodiment, annular or cylindrical) when viewed from the Z-axis direction. That is, the first member 210 has a circular outer shape when viewed from the Z-axis direction, and an opening 211 extending in the Z-axis direction is formed in its center (center position). The opening 211 is a hole (through hole) that penetrates the first member 210 in the Z-axis direction. In this embodiment, the opening 211 has a circular shape when viewed from the Z-axis direction, and a female screw portion 212 with a female screw is provided on the inner surface (inner peripheral surface) of the opening 211. The female screw portion 212 is a portion that is coupled to a male screw portion 223 of the second member 220 described later. That is, the first member 210 functions as a nut that is coupled to the second member 220. The outer shape of the first member 210 is not limited to a circular shape when viewed in the Z-axis direction, but may be any shape, such as an elliptical ring, an oval ring, a square ring, or any other polygonal ring.

The first member 210 extends in the Z-axis direction from the surface (outer surface) of the wall portion 121 in the positive Z-axis direction to the surface (inner surface) in the negative Z-axis direction. The first member 210 is connected (contacted) to the bus bar 20 at the end (end face) in the positive Z-axis direction, and is connected (contacted) to the bus bar 440 at the end (end face) in the negative Z-axis direction. In this way, the first member 210 electrically connects the bus bar 20 outside the case 100 to the bus bar 440 inside the case 100. The bus bar 20 is a conductive member that is disposed outside the energy storage device 10 (case 100) and is connected (joined) to the external terminal 200 to electrically connect the energy storage device 10 to an external device. The material of the bus bar 20 is the same as that of the bus bar 400. As long as the first member 210 can connect (contact) with the bus bars 20 and 440, it may protrude beyond the outer or inner surface of the wall portion 121, or may be recessed inward beyond the outer or inner surface of the wall portion 121.

In this embodiment, the first member 210 is insert molded into the wall portion 121 and joined (fixed) to the wall portion 121. In other words, the first member 210 is embedded in the wall portion 121 when the case lid body 120 is molded and molded together, thereby being inserted into the wall portion 121. The first member 210 may be pressed into the wall portion 121 after molding (heat may be applied when pressing in), and joined (fixed) to the wall portion 121. The material of the first member 210 is not particularly limited as long as it is conductive, such as aluminum, aluminum alloy, copper, copper alloy, nickel, etc., but in this embodiment, it is brass.

The second member 220 is a member that protrudes outward from the case 100 more than the first member 210, and the tensile strength of the second member 220 is higher than that of the first member 210. The material of the second member 220 is not particularly limited to stainless steel, iron, steel, etc., but in this embodiment, it is steel. That is, in this embodiment, the first member 210 is brass, and the second member 220 is steel whose tensile strength is higher than that of brass. The second member 220 only needs to have a tensile strength higher than that of the first member 210, and does not need to be conductive. The tensile strength is the maximum strength of a member against a tensile force (the strength at which the member breaks when pulled). The tensile strength is measured in accordance with the measurement conditions of JIS Z2241, and the tensile strength of the first member 210 and the tensile strength of the second member 220 are compared. The tensile strength of the second member 220 is preferably about 400 MPa or more, and more preferably about 800 MPa or more. The tensile strength of the first member 210 needs only to be lower than the tensile strength of the second member 220, but more preferably the tensile strength of the first member 210 is approximately 295 MPa to 380 MPa.

Furthermore, the volume resistivity of the first member 210 is preferably lower than that of the second member 220. In other words, the volume resistivity of the material of the first member 210 is preferably lower than that of the material of the second member 220. In other words, it is preferable that the first member 210 is more conductive than the second member 220. In this embodiment, as described above, the material of the second member 220 is steel, and the material of the first member 210 is brass, which has a lower volume resistivity than steel. When comparing the volume resistivity of the first member 210 and the volume resistivity of the second member 220, the measurements are performed in accordance with the measurement conditions of JIS C2525. When the volume resistivity of the first member 210 exceeds the numerical range of the volume resistivity that can be measured under the measurement conditions of JIS C2525, the volume resistivity of the first member 210 is measured in accordance with the measurement conditions of JIS H0505. The same applies to the volume resistivity of the second member 220. The volume resistivity of the first member 210 thus obtained is compared with that of the second member 220. The volume resistivity of the first member 210 is preferably about 1.0×10 ⁻⁸ Ωm to 7.0×10 ⁻⁸ Ωm (at 20° C.). The volume resistivity of the first member 210 is more preferably about 1.0×10 ⁻⁸ Ωm to 2.0×10 ⁻⁸ Ωm, which allows better electrical conductivity. When the volume resistivity of the first member 210 is 5.0×10 ⁻⁸ Ωm to 7.0×10 ⁻⁸ Ωm, processing is easy. The volume resistivity of the second member 220 should be higher than that of the first member 210.

The second member 220 penetrates the first member 210 from the negative Z-axis direction of the first member 210 toward the positive Z-axis direction, and is connected to the first member 210. The second member 220 protrudes outward (in the positive Z-axis direction) from the wall portion 121 of the case lid body 120 beyond the first member 210, and is connected to the connecting member 230. In this way, the second member 220 functions as a bolt that connects the first member 210 and the connecting member 230. In this way, the second member 220 fixes the busbars 20 and 440 to the first member 210.

Specifically, the second member 220 has a head 221, an inner portion 222, a protruding portion 224, and a washer portion 225. The head 221 is disposed at the end of the second member 220 in the negative Z-axis direction, and is a portion that is flat in the Z-axis direction and is larger in size than the inner portion 222 when viewed in the Z-axis direction. The washer portion 225 is disposed in the positive Z-axis direction of the head 221 when the inner portion 222 is inserted, and is an annular member that is flat in the Z-axis direction. The head 221 is disposed with the first member 210 sandwiching the bus bar 440 via the washer portion 225. As a result, the bus bar 440 is fixed to the first member 210, and the first member 210 and the bus bar 440 are connected (contacted). The shape of the head 221 and the washer portion 225 when viewed in the Z-axis direction may be a circle (the washer portion 225 is annular) or may be another shape, and is not particularly limited. In this embodiment, the washer portion 225 is a separate member from the head portion 221 and the inner portion 222, but it may be formed integrally with the head portion 221 and the inner portion 222.

The inner portion 222 is a cylindrical portion that protrudes from the head portion 221 in the positive direction of the Z axis. The inner portion 222 is disposed within the first member 210. Specifically, the inner portion 222 is disposed within the portion of the first member 210 that penetrates the case 100 (within a hole formed in the portion). In other words, the inner portion 222 is disposed within a hole formed in the portion of the first member 210 that penetrates the wall portion 121 of the case cover body 120. In this embodiment, since the entire first member 210 is a portion that penetrates the wall portion 121, the inner portion 222 is disposed within the opening 211, which is a hole formed in the first member 210. The inner portion 222 extends in the negative direction of the Z axis from the surface of the first member 210 in the positive direction of the Z axis, straddles the surface of the first member 210 in the negative direction of the Z axis (protrudes in the negative direction of the Z axis beyond the first member 210), and extends to the head portion 221.

In this embodiment, the outer surface (outer peripheral surface) of the inner portion 222 is provided with a male threaded portion 223 having a male thread. The inner portion 222 penetrates the bus bar 440, and is inserted into the opening 211 with the male threaded portion 223 engaging with the female threaded portion 212 provided in the opening 211, and is disposed within the opening 211. In this manner, the second member 220 has the male threaded portion 223, and the first member 210 has the female threaded portion 212 that engages with the male threaded portion 223. As a result, the second member 220 is fixed to the first member 210, and the head portion 221 (and the washer portion 225) is disposed with the bus bar 440 sandwiched between it and the first member 210.

The protruding portion 224 is a cylindrical portion that protrudes from the inner portion 222 in the positive direction of the Z axis. That is, the protruding portion 224 protrudes from the inner portion 222 to the outside of the case 100 (outside the wall portion 121 of the case lid 120). In this embodiment, the cross-sectional area of the inner portion 222 in a plane (XY plane) perpendicular to the protruding direction (Z axis direction) of the protruding portion 224 is larger than the cross-sectional area of the protruding portion 224 in a plane (XY plane) perpendicular to the protruding direction (Z axis direction). That is, the cross-sectional area of the protruding portion 224 is smaller than that of the inner portion 222 (its size when viewed from the Z axis direction is smaller). Specifically, the protruding portion 224 has a smaller diameter than the inner portion 222. The cross-sectional area is measured using a three-dimensional measuring machine.

In this embodiment, the outer surface (outer peripheral surface) of the protruding portion 224 is provided with a male thread portion having a male screw formed thereon, similar to the inner portion 222. The protruding portion 224 penetrates the busbar 20, and is inserted into the connecting member 230 while the male thread portion is engaged with a female thread portion provided on the connecting member 230, and is connected to the connecting member 230. As a result, the connecting member 230 is fixed to the second member 220, and the connecting member 230 is arranged in a state in which the busbar 20 is sandwiched between the connecting member 230 and the first member 210. In this way, the protruding portion 224 functions as a bolt, and the connecting member 230 functions as a nut.

The connecting member 230 is disposed in the positive Z-axis direction of the first member 210 and the inner portion 222, and is a portion that is flat in the Z-axis direction and is larger than the inner portion 222 when viewed in the Z-axis direction. The connecting member 230 is disposed in a state where it sandwiches the bus bar 20 with the first member 210. As a result, the bus bar 20 is fixed to the first member 210, and the first member 210 and the bus bar 20 are connected (contacted). The shape of the connecting member 230 when viewed in the Z-axis direction may be a circular shape (annular shape) or may be another shape, and is not particularly limited. The connecting member 230 has a flat annular washer portion 231 in the Z-axis direction at a position where the connecting member 230 sandwiches the bus bar 20 with the first member 210. The connecting member 230 may have the washer portion 231 integrally therewith, or may have a separate washer portion 231.

In the second member 220, adhesive may be applied to the male threaded portion 223 of the inner portion 222, thereby firmly connecting the inner portion 222 to the first member 210. Similarly, adhesive may be applied to the male threaded portion of the protruding portion 224, thereby firmly connecting the protruding portion 224 to the connecting member 230.

[4. Description of Effects]
As described above, according to the energy storage device 10 according to the embodiment of the present invention, the external terminal 200 is divided into a conductive first member 210 penetrating the case 100 and a second member 220 protruding outward from the case 100 beyond the first member 210. The tensile strength of the second member 220 is made higher than that of the first member 210. As a result, in the external terminal 200, the first member 210 can electrically connect the internal and external conductive members (busbars 440 and 20 in this embodiment) of the case 100 to each other, and the second member 220 can be used to join the external terminal 200 and the external conductive member (busbar 20). Since the tensile strength of the second member 220 is higher than that of the first member 210, even if a load such as a tensile load or a torsional load is applied to the second member 220 when the external terminal 200 and the external conductive member (busbar 20) are joined, the second member 220 can be prevented from being damaged (e.g., broken). Therefore, damage to the external terminals 200 in the energy storage device 10 can be suppressed.

By reducing the volume resistivity of the first member 210 in the external terminal 200, electricity can flow through the first member 210 (external terminal 200) with low resistance, and the output characteristics of the energy storage device 10 can be maintained.

In the external terminal 200, the second member 220 is configured such that a protruding portion 224 protrudes outward from the case 100 from an inner portion 222 within the portion of the first member 210 that penetrates the case 100. This makes it possible to easily position (fix) the second member 220 relative to the first member 210, and also prevents the protruding portion 224 of the second member 220 from protruding too far from the case 100.

In the external terminal 200, the second member 220 is configured to penetrate the first member 210, so that the second member 220 can be easily positioned (fixed) relative to the first member 210.

In the external terminal 200, the first member 210 and the second member 220 are joined with screws, so that the second member 220 can be firmly fixed to the first member 210. Joining the first member 210 and the second member 220 with screws reduces variation in the joined portion compared to joining the first member 210 and the second member 220 by press fitting.

In the external terminal 200, by increasing the cross-sectional area of the inner portion 222 of the second member 220, the inner portion 222 can withstand a large external torque. By decreasing the cross-sectional area of the protruding portion 224 of the second member 220, the torque (fastening torque) applied to the second member 220 can be reduced when fixing an external conductive member (bus bar 20) to the external terminal 200. By decreasing the cross-sectional area of the protruding portion 224 of the second member 220, even if the cross-sectional area of the inner portion 222 is large, the protruding portion 224 can be formed to a size (such as an M8 bolt) suitable for fixing the external terminal 200 to the external conductive member (bus bar 20).

[5. Description of Modifications]
Although the power storage device 10 according to the present embodiment has been described above, the present invention is not limited to the above embodiment. The embodiment disclosed herein is illustrative and not restrictive in all respects, and the scope of the present invention includes all modifications within the meaning and scope of the claims.

(Variation 1)
In the above embodiment, the first member 210 and the second member 220 of the external terminal 200 are joined by screws, but this is not limited to this. Fig. 5 is a cross-sectional view showing the configuration of an external terminal 200a according to a first modified example of the present embodiment. Fig. 5 is a view corresponding to Fig. 4.

5, the external terminal 200a in this modified example has a first member 210a instead of the first member 210 in the above embodiment, and has an inner portion 222a instead of the inner portion 222 of the second member 220 in the above embodiment. Unlike the first member 210, the first member 210a does not have a female thread portion 212. Unlike the inner portion 222, the inner portion 222a does not have a male thread portion 223. In other words, the first member 210a has an opening 211a in which a female thread is not formed, and the inner portion 222a does not have a male thread. In this modified example, the inner portion 222a is pressed into the opening 211a of the first member 210a and is joined (fixed) to the first member 210a. In this case, the press-in may be performed after forming an uneven portion by knurling or the like on the outer surface of the inner portion 222a. The inner portion 222a may be joined (fixed) to the first member 210a by adhesion. The rest of the configuration of this modification is the same as the above embodiment, so a detailed description will be omitted.

This modified example provides the same effects as the above embodiment. In particular, in this modified example, by not forming a female thread on the first member 210a and not forming a male thread on the inner portion 222a, there is no need to form a threaded portion on the external terminal 200a, and the external terminal 200a can be easily formed. The inner surface of the opening 211a of the first member 210a and the outer surface of the inner portion 222a are not limited to having a circular shape when viewed from the Z-axis direction, and may have any shape, such as an elliptical shape, an oval shape, a square shape, or any other polygonal shape.

(Variation 2)
In the above embodiment, the inner portion 222 and the protruding portion 224 of the second member 220 of the external terminal 200 have different sizes (diameters) when viewed in the Z-axis direction, but this is not limited to the above. Fig. 6 is a cross-sectional view showing the configuration of an external terminal 200b according to a second modification of the present embodiment. Fig. 6 is a view corresponding to Fig. 4.

6, the external terminal 200b in this modification has a first member 210b instead of the first member 210 in the above embodiment, and has an inner portion 222b instead of the inner portion 222 of the second member 220 in the above embodiment. The inner portion 222b has a male thread portion on its outer surface (outer circumferential surface) like the inner portion 222, but unlike the inner portion 222, it has the same size (diameter) as the protruding portion 224 when viewed from the Z-axis direction. The first member 210b has an opening 211b of a size (diameter) corresponding to the inner portion 222b, and the opening 211b has a female thread portion that engages with the male thread portion of the inner portion 222b. The other configurations of this modification are the same as those of the above embodiment, so detailed description will be omitted.

This modified example provides the same effects as the above embodiment. In particular, in this modified example, the inner portion 222b and the protruding portion 224 of the second member 220 have the same size (diameter) when viewed from the Z-axis direction, so there is no need to provide a step in the second member 220, and the second member 220 can be easily formed. In this modified example, as in the above modified example 1, the first member 210b and the inner portion 222b may be joined by press-fitting, adhesive, or the like.

(Variation 3)
In the above embodiment, the second member 220 of the external terminal 200 penetrates the first member 210, but this is not limited to the above. Fig. 7 is a cross-sectional view showing the configuration of an external terminal 200c according to a third modification of the present embodiment. Fig. 7 is a view corresponding to Fig. 4.

7, the external terminal 200c in this modified example has a first member 210c instead of the first member 210 in the above embodiment, and has

inner portions

222c and 222d instead of the inner portion 222 of the second member 220 in the above embodiment. The

inner portions

222c and 222d are the inner portion 222 separated in the Z-axis direction. The first member 210c has

openings

211c and 211d corresponding to the

inner portions

222c and 222d. In other words, the

openings

211c and 211d are recesses rather than through holes, and the second member 220 (

inner portions

222c and 222d) do not penetrate the first member 210c. In this modified example, the

inner portions

222c and 222d have different sizes (diameters) when viewed from the Z-axis direction, but may be the same size (diameter) when viewed from the Z-axis direction, and the size (diameter) when viewed from the Z-axis direction is not particularly limited. In this modification, the

inner portions

222c and 222d and the

openings

211c and 211d are joined by screws as in the above embodiment, but they may also be joined by press-fitting or adhesive as in the above modification 1. The rest of the configuration of this modification is the same as in the above embodiment, so a detailed description will be omitted.

This modification provides the same effects as the above embodiment. In particular, in this modification, since the second member 220 is separated into two parts by the

inner portions

222c and 222d, the bus bar 20 and the bus bar 440 can be fixed individually to the first member 210. Therefore, even if the fixation of the bus bar 20 becomes loose due to the rotation of the inner portion 222c, the fixation of the bus bar 440 by the inner portion 222d can be prevented from becoming loose, and the

inner portions

222c and 222d can be prevented from affecting each other. In this modification, the

openings

211c and 211d may be connected.

(Other Modifications)
In the above embodiment, the external terminals 200 are arranged on the wall 121 of the case cover 120, but they may be arranged on any wall of the case cover 120, or on any wall of the case body 110. In other words, the external terminals 200 may be arranged only on the wall of the case body 110. When the external terminals 200 are arranged on a wall of the case body 110, the first member 210 penetrates the wall of the case body 110, and the second member 220 protrudes outward from the wall of the case body 110 further than the first member 210.

In the above embodiment, the volume resistivity of the first member 210 in the external terminal 200 is lower than the volume resistivity of the second member 220, but it may be the same as or higher than the volume resistivity of the second member 220.

In the above embodiment, in the external terminal 200, the inner portion 222 is arranged in a portion of the first member 210 that penetrates the case 100, but this is not limited to the above. The first member 210 may protrude from the case 100, and the inner portion 222 may be arranged in a portion of the first member 210 that protrudes from the case 100. In this case, the protruding portion 224 may protrude outward from the case 100 from within the portion of the first member 210 that protrudes from the case 100. The inner portion 222 may not be arranged in the first member 210, but may be arranged in a position in the second member 220 adjacent to the first member 210, or in a position surrounding the first member 210, or the like. In this case, the protruding portion 224 may protrude outward from the case 100 from within a portion of the second member 220 adjacent to the first member 210, or in a position surrounding the first member 210.

In the above embodiment, in the external terminal 200, the protrusion 224 of the second member 220 and the connecting member 230 are connected by screws, but they may be joined by a method other than screws, such as press-fitting or adhesive. This also makes it possible to suppress damage to the external terminal 200 by providing the second member 220 with a high tensile strength.

　Any combination of the components included in the above embodiment and its variations is also included within the scope of the present invention.

The present invention can be applied to energy storage devices equipped with energy storage elements such as lithium-ion secondary batteries.

REFERENCE SIGNS LIST 10

Energy storage device

20, 400, 410, 420, 430, 440 Bus bar 100 Case 110 Case body 120 Case cover 121

Wall

200, 200a, 200b, 200c

External terminal

210, 210a, 210b, 210c

First member

211, 211a, 211b, 211c, 211d Opening 212 Female thread 220 Second member 221

Head

222, 222a, 222b, 222c, 222d Inner side 223 Male thread 224

Protruding portion

225, 231 Washer 230 Joining member 300 Energy storage element 310 Element container 320 Container body 330 Container cover 331 Gas exhaust valve 340 Terminal 350 Gasket

Claims

A storage element;
A case that houses the power storage element;
an external terminal disposed on the case;
The external terminal is
a conductive first member penetrating the case;
a second member protruding outwardly from the case further than the first member,
The second member has a higher tensile strength than the first member.
The power storage device according to claim 1 , wherein the first member has a lower volume resistivity than the second member.
The second member is
an inner portion disposed within a portion of the first member that penetrates the case;
The power storage device according to claim 1 , further comprising: a protrusion protruding from the inner portion to an outside of the case.
The power storage device according to claim 1 , wherein the second member penetrates the first member.
The power storage device according to claim 1 , wherein the second member has a male thread portion, and the first member has a female thread portion that is coupled to the male thread portion.
The second member is
an inner portion disposed within the first member;
a protrusion protruding from the inner portion to an outside of the case,
The power storage device according to claim 1 , wherein a cross-sectional area of the inner portion in a plane perpendicular to a protruding direction of the protruding portion is larger than a cross-sectional area of the protruding portion in a plane perpendicular to the protruding direction.