Energy storage element

Abstract

To provide a power storage element, equipped with a container and an electrode terminal, which has improved reliability.SOLUTION: A power storage element comprises: a container 100; and an electrode terminal 130A which has an outer end part 138 located outside a lid body 120 of the container 100 and an inner end part 139 located inside the lid body 120. The electrode terminal 130A has: a first conductive member 131 which includes the outer end part 138 and is made of a first material; and a second conductive member 132 which includes the inner end part 139. The second conductive member 132 has a first material part 133 and a second material part 134 which are bonded to each other. The first material part 133 is made of the first material and is bonded to the first conductive member 131. The second material part 134 is made of a second material different from the first material part 133, and includes the inner end part 139. At least the periphery of a bonding interface, in the electrode terminal 130A, between the first material part 133 and the second material part 134 is covered with an insulation member 141.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an energy storage element including a container and an electrode terminal. [Background technology]

[0002] Patent Document 1 discloses a battery (electricity storage element) having a metal housing member as a container. This housing member has an opening, and a conductor (electrode terminal) is disposed in a state penetrating a glass material that seals this opening. The electrode terminal has a first portion made of a first material (e.g., aluminum) and a second portion made of a second material (e.g., copper), which are aligned in the axial direction, as well as a transition portion from the first material to the second material. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-74296 A Summary of the Invention [Problem to be solved by the invention]

[0004] Conventionally, for example, a bus bar joined to an electrode terminal outside a container of an electric storage element and a current collector joined to an electrode terminal inside the container may be formed of different kinds of materials. In this case, as in the above conventional electric storage element, it is advantageous to configure the electrode terminal with a plurality of members formed of different kinds of materials from the viewpoint of improving the joinability (ease of joining or joining quality, etc.) of the electrode terminal with other members inside and outside the container. However, when manufacturing an electrode terminal configured in this manner, as in the above conventional electrode terminal, it is necessary to join two members formed of different kinds of materials and having the same outer diameter in the axial direction. In this case, since it is difficult to join different materials with normal welding such as laser welding, a joining method involving a large pressure force such as friction diffusion joining is used. As a result, a joining mark is generated at the boundary portion between the two members on the outer circumferential surface of the electrode terminal. In this case, the joining mark present on the outer circumferential surface of the electrode terminal affects the airtightness of the sealed portion around the electrode terminal in the container, which may reduce the reliability of the electric storage element.

[0005] The present invention was made by the inventor of the present application by focusing on the above-mentioned problem, and aims to provide an energy storage element having a container and electrode terminals, which has improved reliability. [Means for solving the problem]

[0006] An energy storage element according to one embodiment of the present invention comprises a container and an electrode terminal having an outer end located outside a wall portion of the container and an inner end located inside the wall portion, the electrode terminal having a first conductive member including the outer end and formed of a first material, and a second conductive member including the inner end and having a first material portion and a second material portion joined to each other, the first material portion being formed of the first material and joined to the first conductive member, the second material portion being formed of a second material different from the first material portion and including the inner end, and at least the periphery of the joint interface between the first material portion and the second material portion in the electrode terminal is covered with an insulating member.

[0007] According to this configuration, for example, the outer end of the electrode terminal can be formed of a first material to match the bus bar to which it is joined, and the inner end can be formed of a second material to match the current collector to which it is joined. This makes it easy to weld the outer end to the bus bar, and easy to weld the inner end to the current collector. In addition, in an electrode terminal composed of a first conductive member and a second conductive member, the first material part of the second conductive member is formed of the same material (first material) as the first conductive member to which it is directly joined. Therefore, the second conductive member and the first conductive member can be easily joined by a joining method that is unlikely to leave a joining mark on the outer peripheral surface, such as welding in the axial direction of the electrode terminal. Therefore, problems such as a decrease in airtightness due to joining marks on the outer peripheral surface of the electrode terminal are suppressed. Furthermore, since the periphery of the joining interface between the first material part and the second material part in the second conductive member is covered with an insulating member, corrosion caused by the electrolyte coming into contact with the joining interface between different materials is suppressed. In this way, the energy storage element of this embodiment can improve reliability.

[0008] The first material part may have an exposed portion that is not covered by the second material part on a side of the joint interface, and the first conductive member and the first material part may be joined by a weld formed through the exposed portion.

[0009] According to this configuration, the welded portion that joins the second conductive member and the first conductive member is formed in a state in which it penetrates the exposed portion of the first material portion. In other words, since the first material portion and the first conductive member are welded at a position where the second material portion is not disposed, the overlapping portion of the first material portion and the second material portion can be welded with less energy than when welding the first conductive member. Therefore, for example, an electrode terminal that improves the reliability of an energy storage element can be more efficiently manufactured. Or, problems such as the appearance of joining marks (welding marks) on the outer circumferential surface of the electrode terminal due to heat during welding are less likely to occur.

[0010] The first conductive member and the first material portion may be joined by a weld portion formed through a portion where the second material portion and the first material portion are overlapped.

[0011] According to this configuration, a weld is formed that penetrates the first material part and the second material part, so that, for example, when viewed from the overlapping direction of the first material part and the second material part, a wide area of ​​the first material part can be joined to the second material part. In other words, the joining area between the first material part and the second material part can be relatively large, and this can reduce the electrical resistance in the conductive path formed by the second conductive member. This also contributes to improving the reliability of the energy storage element.

[0012] The insulating member may be made of glass or crystallized glass.

[0013] According to this configuration, the bonding interface between the first material part and the second material part is protected by glass or crystallized glass (also called glass ceramic), which has high chemical stability, and therefore the effect of suppressing corrosion caused by the electrolyte is improved. In addition, since the insulating member is made of glass or the like, its heat resistance is improved, thereby reducing the possibility that the insulating member will be damaged by heat generated when a current collector or the like is bonded to the inner end of the electrode terminal.

[0014] The second conductive member may be a clad material in which the first material portion and the second material portion are roll-bonded.

[0015] According to this configuration, since the second conductive member is a clad material, for example, the second conductive member can be mass-produced, that is, second conductive members of uniform quality can be easily obtained, which reduces the manufacturing cost of the energy storage element with improved reliability. Effect of the Invention

[0016] According to the present invention, it is possible to provide an energy storage element including a container and electrode terminals, and the energy storage element has improved reliability. [Brief description of the drawings]

[0017] [Figure 1] 1 is a perspective view showing the appearance of an energy storage element according to an embodiment; [Diagram 2] 1 is a first exploded perspective view of an energy storage element according to an embodiment. FIG. [Diagram 3] 4 is a second exploded perspective view of the energy storage element according to the embodiment. FIG. [Figure 4] 2 is a cross-sectional view showing the configuration of an electrode terminal and its surroundings according to the embodiment; FIG. [Diagram 5] 4 is an enlarged cross-sectional view showing a configuration of an electrode terminal and a sealing member according to the embodiment. FIG. [Figure 6] 13 is an enlarged cross-sectional view showing a configuration of an electrode terminal and a sealing member according to a modified example of the embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, with reference to the drawings, a description will be given of an energy storage element according to an embodiment (including modified examples) of the present invention. Note that the embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, arrangement and connection forms 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. Furthermore, in each drawing, the dimensions are not strictly shown. Furthermore, in each drawing, the same or similar components are given the same symbols.

[0019] In the following description and drawings, the X-axis direction is defined as the arrangement direction of a pair of electrode terminals (negative and positive, hereinafter the same) of an energy storage element, the arrangement direction of a pair of current collectors, the winding axis direction of the electrode body, or the opposing direction of the short side surfaces of a container. The Y-axis direction is defined as the opposing direction of the long side surfaces of the container, the short direction of the short side surfaces of the container, or the thickness direction of the container. The Z-axis direction is defined as the arrangement direction of the container body and lid of an energy storage element, the longitudinal direction of the short side surfaces of the container, or the extension direction of the legs of the current collectors. The X-axis, Y-axis, and Z-axis directions intersect each other (orthogonal in this embodiment).

[0020] In the following description, for example, the positive X-axis direction indicates the direction of the X-axis arrow, and the negative X-axis direction indicates the opposite direction to the positive X-axis direction. The same applies to the Y-axis and Z-axis directions. Furthermore, expressions indicating relative directions or attitudes, such as parallel and perpendicular, also include cases where the directions or attitudes are not strictly speaking the same. For example, two directions being parallel does not only mean that the two directions are completely parallel, but also means that the directions are substantially parallel, that is, that there is a difference of, for example, about a few percent.

[0021] (Embodiment) [1. General description of energy storage elements] First, an energy storage element 10 according to the present embodiment will be generally described with reference to Fig. 1 and Fig. 2. Fig. 1 is a perspective view showing the appearance of the energy storage element 10 according to the embodiment. Fig. 2 is a first exploded perspective view of the energy storage element 10 according to the embodiment. Specifically, Fig. 2 shows a state in which a container body 110 is separated from the energy storage element 10.

[0022] The energy storage element 10 is a secondary battery (single cell) capable of charging and discharging electricity, and more specifically, a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery. The energy storage element 10 is used as a battery for driving or starting an engine of a moving body such as an automobile, a motorcycle, a watercraft, a ship, a snowmobile, an agricultural machine, a construction machine, or a railway vehicle for an electric railway. Examples of the automobile include an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), and a gasoline-powered vehicle. Examples of the railway vehicle for the electric railway include a train, a monorail, a linear motor car, and a hybrid train equipped with both a diesel engine and an electric motor. The energy storage element 10 can also be used as a stationary battery for home or business use.

[0023] The energy storage element 10 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 energy storage element 10 may not be a secondary battery, but may be a primary battery that allows the user to use stored electricity without charging it. The energy storage element 10 may be a battery using a solid electrolyte. In the present embodiment, the energy storage element 10 is illustrated as having a rectangular parallelepiped (angled) shape, but the shape of the energy storage element 10 is not limited to a rectangular parallelepiped shape, and may be a cylindrical shape, an oval cylindrical shape, or a polygonal prism shape other than a rectangular parallelepiped, etc.

[0024] As shown in FIG. 1, the energy storage element 10 includes a container 100, negative and positive electrode terminals 130, and a sealing member 140 that seals the attachment portion of the electrode terminals 130 in the container 100. An electrode body 200 and negative and positive electrode collectors 300 are housed inside the container 100. In this embodiment, when the negative and positive electrode terminals 130 are to be distinguished from each other, the negative electrode electrode terminal 130 is referred to as electrode terminal 130A, and the positive electrode electrode terminal 130 is referred to as electrode terminal 130B. Furthermore, when the negative and positive electrode collectors 300 are to be distinguished from each other, the negative electrode collector 300 is referred to as collector 300A, and the positive electrode collector 300 is referred to as collector 300B. An electrolyte (non-aqueous electrolyte) is enclosed inside the container 100, but is not shown in the figure. The electrolyte solution is not particularly limited in type, and various types can be selected as long as they do not impair the performance of the energy storage element 10. Furthermore, a spacer, an insulating film, and the like (not shown) may be disposed inside the container 100.

[0025] The container 100 is a rectangular parallelepiped (angular) container having a container body 110 with an opening formed therein, and a lid 120 that closes the opening of the container body 110. The container body 110 is a rectangular tubular member with a bottom that constitutes the main body of the container 100, and has short side portions 111 on both sides in the X-axis direction, long side portions 112 on both sides in the Y-axis direction, and a bottom wall portion 113 on the negative Z-axis side. The short side portion 111 is a wall portion that forms the short side of the container 100, and the long side portion 112 is a wall portion that forms the long side of the container 100.

[0026] The lid body 120 is a rectangular plate-like member constituting a lid portion of the container 100, and is disposed on the positive side of the container body 110 in the Z-axis direction. That is, the lid body 120 is a wall portion that faces the bottom wall portion 113 and is adjacent to the short side surface portion 111 and the long side surface portion 112. In this embodiment, the lid body 120 has negative and positive electrode terminals 130 fixed thereto. The lid body 120 may further be provided with a gas exhaust valve that releases pressure when the pressure inside the container 100 increases, and a liquid injection port for injecting an electrolyte into the container 100, and the like.

[0027] With this configuration, the container 100 is structured so that the electrode body 200 with the pair of current collectors 300 connected thereto is housed inside the container body 110, and then the container body 110 and the lid body 120 are joined by welding or the like, thereby sealing the inside. The container body 110 and the lid body 120 are formed of a weldable metal, such as stainless steel, aluminum, or an aluminum alloy.

[0028] The electrode body 200 is an electricity storage element (power generation element) that includes a positive electrode plate, a negative electrode plate, and a separator and can store electricity. The positive electrode plate is an electrode plate in which a composite layer containing a positive electrode active material is formed on a positive electrode base layer that is a long strip-shaped current collector foil made of aluminum or an aluminum alloy. The negative electrode plate is an electrode plate in which a composite layer containing a negative electrode active material is formed on a negative electrode base layer that is a long strip-shaped current collector foil made of copper or a copper alloy. As the current collector foil, nickel, iron, stainless steel, titanium, baked carbon, conductive polymer, conductive glass, Al-Cd alloy, and other known materials can be used as appropriate. As the positive electrode active material and the negative electrode active material used in the composite layer, any known material can be used as long as they are active materials that can absorb and release lithium ions. As the separator, for example, a microporous sheet made of resin or a nonwoven fabric can be used.

[0029] In this embodiment, the electrode body 200 is a wound-type electrode body formed by disposing a separator between a positive electrode plate and a negative electrode plate and winding them. Specifically, the electrode body 200 is wound with a positive electrode plate and a negative electrode plate shifted from each other in the direction of the winding axis (in this embodiment, a virtual axis parallel to the X-axis direction) via the separator. The positive electrode plate and the negative electrode plate have, at the ends in the shifted direction, portions (composite layer non-formed portions) where the composite material containing the active material is not applied (composite layer is not formed) and the base layer is exposed.

[0030] That is, the electrode body 200 has an electrode body main body 210, which is a main body part on which a composite layer is formed, and electrode body ends 220 that protrude from the electrode body main body 210 in the positive direction and the negative direction of the X axis. One of these two electrode body ends 220 is provided with a positive electrode bundling part in which the composite layer non-forming parts of the positive electrode plate are stacked and bundled. The other electrode body end 220 is provided with a negative electrode bundling part in which the composite layer non-forming parts of the negative electrode plate are stacked and bundled. In this embodiment, the electrode body 200 having an oval cross-sectional shape is illustrated, but the cross-sectional shape of the electrode body 200 may be a circle, an ellipse, or the like.

[0031] The electrode terminal 130 is a terminal electrically connected to the positive electrode plate or the negative electrode plate of the electrode body 200 via the current collector 300. In other words, the electrode terminal 130 is a metal member for leading out electricity stored in the electrode body 200 to the external space of the energy storage element 10 and for introducing electricity into the internal space of the energy storage element 10 in order to store electricity in the electrode body 200. As described above, the electrode terminal 130 is fixed to a wall portion (the lid body 120 in this embodiment) disposed above the electrode body 200.

[0032] Specifically, in this embodiment, the electrode terminal 130 is fixed to the lid 120 via the sealing member 140 in a state in which it penetrates the lid 120. An end of the electrode terminal 130 on the inner side (Z-axis negative direction side) of the container 100 is joined to the current collector 300. A conductive member (not shown) such as a bus bar is joined to an end of the electrode terminal 130 on the outer side (Z-axis positive direction side) of the container 100. In this embodiment, the electrode terminal 130 is composed of a plurality of members arranged in the axial direction of the electrode terminal 130. The configuration of the electrode terminal 130 and its surroundings will be described later with reference to Figs. 3 and 4.

[0033] The current collectors 300 are arranged on both sides of the electrode body 200 in the X-axis direction, and are members (positive and negative current collectors) connected to the electrode body end 220. Specifically, a pair of legs 320 of the current collector 300B are joined to the electrode body end 220 on the positive electrode side, and a pair of legs 320 of the current collector 300A are joined to the electrode body end 220 on the negative electrode side. Ultrasonic welding, crimping, or the like is used as a method for joining the current collector 300 and the electrode body end 220. The material of the current collector 300 is not limited, but for example, the positive electrode side current collector 300B is formed of a metal such as aluminum or an aluminum alloy, similar to the positive electrode base layer of the electrode body 200. The negative electrode side current collector 300A is formed of a metal such as copper or a copper alloy, similar to the negative electrode base layer of the electrode body 200.

[0034] [2. Electrode terminal and its surrounding structure] Next, the configuration of the electrode terminal 130A and its periphery in the energy storage element 10 according to the embodiment will be described with reference to Fig. 2 as well as Figs. 3 to 5. Note that this embodiment is characterized by the configuration of the periphery of at least one (electrode terminal 130A) of a pair of electrode terminals 130 included in the energy storage element 10. Therefore, hereinafter, only one electrode terminal 130 (electrode terminal 130A) and its periphery will be illustrated and described.

[0035] Fig. 3 is a second exploded perspective view of the energy storage element 10 according to the embodiment. In Fig. 3, the electrode terminal 130A of the energy storage element 10 and its surrounding components are shown separated. Fig. 4 is a cross-sectional view showing the configuration of the electrode terminal 130A and its surroundings according to the embodiment. Fig. 4 is a partial cross-section of the energy storage element 10, and shows a partial cross-section in the XZ plane passing through the line IV-IV in Fig. 3, with the electrode body 200 and the container body 110 omitted. Fig. 5 is an enlarged cross-sectional view showing the configuration of the electrode terminal 130A and the sealing member 140 according to the embodiment.

[0036] 3 and 4, the electrode terminal 130A according to the present embodiment is fixed to the sealing member 140 in a state in which it penetrates the sealing member 140. The sealing member 140 is inserted into the opening 121 of the lid body 120 and fixed to the lid body 120, so that the electrode terminal 130 is fixed to the container 100 in a state in which it penetrates the opening 121 of the lid body 120. The sealing member 140 has an insulating member 141 that covers the outer peripheral surface of the electrode terminal 130 and has electrical insulation properties, and a sealing main body portion 142 that is disposed along the outer periphery of the insulating member 141 and has electrical conductivity. In other words, the conductive sealing member 140 holds the electrode terminal 130 in a state in which it is electrically insulated from the electrode terminal 130.

[0037] In the present embodiment, the insulating member 141 is, for example, a member formed of glass or crystallized glass (also called glass ceramic), and is a member having electrical insulation and high heat resistance. The sealing body 142 is a member formed of the same material as the container 100, such as aluminum or an aluminum alloy, and is fixed to the cover 120 by welding to the periphery of the opening 121 of the cover 120. In the sealing member 140 that holds the electrode terminal 130 in this configuration, the insulating member 141 is formed, for example, by sintering glass powder. This provides the sealing member 140 that is integrally provided with the electrode terminal 130. That is, the gap between the outer circumferential surface of the electrode terminal 130 and the sealing member 140 is firmly sealed by the insulating member 141 integrated with the electrode terminal 130, and the gap between the sealing member 140 and the periphery of the opening 121 of the container 100 is firmly sealed by welding between metals.

[0038] The electrode terminal 130A thus arranged has an inner end 139 which is an end on the inner side (Z-axis negative direction side) of the container 100, and an outer end 138 which is an end on the outer side (Z-axis positive direction side) of the container 100 (see FIG. 4). The inner end 139 of the electrode terminal 130A penetrates the through hole 151 of the internal insulating plate 150, and is joined to the terminal connection part 310 in a state where it is inserted into the through hole 311 provided in the terminal connection part 310 of the current collector 300A. As a method of this joining, welding such as laser welding is used. Note that it is not essential to provide the through hole 311 in the terminal connection part 310, and for example, the terminal connection part 310 and the electrode terminal 130A may be joined by welding in a state where the end face of the inner end 139 is butted against the upper surface of the terminal connection part 310.

[0039] The internal insulating plate 150 is a member disposed between the lid 120 of the container 100 and the current collector 300, and provides insulation between the lid 120 and the current collector 300. The internal insulating plate 150 is formed in a substantially rectangular shape having a size sufficient to cover the terminal connection portion 310 of the current collector 300 in a plan view (when viewed from the Z-axis direction). The internal insulating plate 150 is formed from an electrically insulating resin material such as polypropylene (PP), polyethylene (PE), polyphenylene sulfide resin (PPS), polyethylene terephthalate (PET), polyether ether ketone (PEEK), tetrafluoroethylene perfluoroalkyl vinyl ether (PFA), polytetrafluoroethylene (PTFE), polybutylene terephthalate (PBT), polyether sulfone (PES), or the like.

[0040] A bus bar, for example, is joined to the outer end 138 of the electrode terminal 130A. Specifically, the end face of the outer end 138 and the bus bar are joined by, for example, laser welding. The bus bar to which the outer end 138 is joined is generally made of aluminum or an aluminum alloy from the viewpoints of weight reduction and good electrical conductivity. In contrast, the current collector 300A to which the inner end 139 is joined is made of copper or a copper alloy, similar to the negative electrode substrate layer of the electrode body 200.

[0041] That is, it is desired that the electrode terminal 130A is electrically and mechanically joined to two different kinds of metal members in a good state. Therefore, in this embodiment, the electrode terminal 130A has a first conductive member 131 having an outer end 138 and a second conductive member 132 having an inner end 139. The first conductive member 131 is formed of a first material, and a portion of the second conductive member 132 including the inner end 139 is formed of a second material different from the first material. Furthermore, a portion of the second conductive member 132 that is joined to the first conductive member 131 is formed of the same material (first material) as the first conductive member 131. The first conductive member 131 and the second conductive member 132 thus configured are joined by welding, thereby forming a welded portion 136 as shown in FIG. 5. Note that FIG. 5 shows a schematic cross section of the welded portion 136, and the shape, number, and position of the welded portion 136 are not limited to the shape, number, and position shown in FIG. 5.

[0042] Thus, the energy storage element 10 according to the present embodiment includes a container 100 and an electrode terminal 130A having an outer end 138 located outside the lid 120 of the container 100 and an inner end 139 located inside the lid 120. The electrode terminal 130A includes a first conductive member 131 including the outer end 138 and formed of a first material, and a second conductive member 132 including the inner end 139. The second conductive member 132 includes a first material portion 133 and a second material portion 134 joined to each other. The first material portion 133 is formed of a first material and joined to the first conductive member 131. The second material portion 134 is formed of a second material different from the first material portion 133 and includes the inner end 139. At least the periphery of the joint interface between the first material portion 133 and the second material portion 134 in the electrode terminal 130A is covered with an insulating member 141.

[0043] In this manner, in the present embodiment, the outer end 138 of the electrode terminal 130A can be formed of a first material (for example, an aluminum alloy) in accordance with the bus bar to which it is joined. Furthermore, the inner end 139 can be formed of a second material (for example, a copper alloy) in accordance with the current collector 300A to which it is joined. This allows the outer end 138 to be easily welded to the bus bar, and allows the inner end 139 to be easily welded to the current collector 300A. Furthermore, in the electrode terminal 130A that is composed of the first conductive member 131 and the second conductive member 132, the first material portion 133 of the second conductive member 132 is formed of the same type of material (first material) as the first conductive member 131 to which it is directly joined. Therefore, the second conductive member 132 and the first conductive member 131 can be easily joined by a joining method that is unlikely to leave a joining mark on the outer circumferential surface, such as welding in the axial direction (Z-axis direction) of the electrode terminal 130A. Therefore, the occurrence of problems such as a decrease in airtightness caused by joining marks on the outer circumferential surface of the electrode terminal 130A is suppressed. Furthermore, since the periphery of the joint interface between the first material part 133 and the second material part 134 in the second conductive member 132 is covered with the insulating member 141, corrosion caused by contact of the electrolyte with the joint interface between the different materials is suppressed. In this way, the energy storage element of this embodiment can improve reliability.

[0044] 5, the first material part 133 has an exposed part 135 that is not covered by the second material part 134 on a side of the joint interface with the second material part 134 (on a radial side of the electrode terminal 130A). The first conductive member 131 and the first material part 133 are joined by a welded part 136 formed to penetrate the exposed part 135.

[0045] In this manner, in the present embodiment, the welded portion 136 that joins the second conductive member 132 and the first conductive member 131 is formed in a state in which it penetrates the exposed portion 135 of the first material portion 133. That is, since the first material portion 133 and the first conductive member 131 are welded at a position where the second material portion 134 is not disposed, the portion where the first material portion 133 and the second material portion 134 are overlapped can be welded with less energy than when welding the first conductive member 131. Therefore, for example, the electrode terminal 130A that improves the reliability of the energy storage element 10 can be more efficiently manufactured. Alternatively, problems such as the appearance of joining marks (welding marks) on the outer circumferential surface of the electrode terminal 130A due to heat during welding are unlikely to occur.

[0046] In addition, in this embodiment, the insulating member 141 is made of glass or crystallized glass. Therefore, the bonding interface between the first material portion 133 and the second material portion 134 is protected by glass or crystallized glass, which has high chemical stability, and the effect of suppressing corrosion caused by the electrolyte is improved. Furthermore, by forming the insulating member 141 from glass or the like, the heat resistance is improved, thereby reducing the possibility that the insulating member 141 will be damaged by heat generated when the current collector 300A is bonded to the inner end portion 139 of the electrode terminal 130A.

[0047] In the present embodiment, the second conductive member 132 of the electrode terminal 130A is a clad material in which the first material part 133 and the second material part 134 are roll-bonded. That is, the first material part 133 and the second material part 134, which are made of different metals, are rolled, for example, in a superposed state, and thus diffusion-bonded. That is, alloying occurs at the boundary surface between the first material part 133 and the second material part 134 due to element diffusion, and therefore the first material part 133 and the second material part 134 are bonded extremely firmly.

[0048] In this way, since a clad material is used as the second conductive member 132, for example, the second conductive member 132 can be mass-produced, that is, it becomes easy to obtain second conductive members 132 of uniform quality. This reduces the manufacturing cost of the energy storage device 10 with improved reliability, for example.

[0049] Although the energy storage element 10 according to the embodiment of the present invention has been described above, the energy storage element 10 may have electrode terminals having a configuration different from the electrode terminals 130 shown in Figures 2 to 5. Therefore, modified examples of the electrode terminals 130 will be described with reference to Figure 6, focusing on the differences from the above embodiment.

[0050] [3. Modifications] FIG. 6 is an enlarged cross-sectional view showing the configuration of an electrode terminal 130Aa and a sealing member 140 according to a modification of the embodiment. The electrode terminal 130Aa according to this modification has a first conductive member 131a including an outer end 138a and formed of a first material, and a second conductive member 132a including an inner end 139a. The second conductive member 132a has a first material portion 133a and a second material portion 134a joined to each other. The first material portion 133a is formed of a first material (e.g., an aluminum alloy) and is joined to the first conductive member 131a. The second material portion 134a is formed of a second material (e.g., a copper alloy) different from the first material portion 133 and includes an inner end 139a. At least the periphery of the joint interface between the first material portion 133a and the second material portion 134a in the electrode terminal 130Aa is covered with an insulating member 141. Thus, the basic configuration of the electrode terminal 130Aa according to this modification is common to the electrode terminal 130A according to the embodiment.

[0051] In this modification, the manner in which the first conductive member 131a and the second conductive member 132a are joined in the electrode terminal 130Aa differs from that in the electrode terminal 130 according to the embodiment. Specifically, in this modification, the first conductive member 131a and the first material portion 133a are joined by a welded portion 136 formed to penetrate a portion where the second material portion 134a and the first material portion 133a are overlapped.

[0052] According to this configuration, since the welded portion 136 is formed penetrating the first material portion 133a and the second material portion 134a, for example, when viewed from the overlapping direction of the first material portion 133a and the second material portion 134a, a wide area of ​​the first material portion 133a can be joined to the second material portion 134a. In other words, the joining area between the first material portion 133a and the second material portion 134a can be relatively large, and this can reduce the electrical resistance in the conductive path formed by the second conductive member 132a. This also contributes to improving the reliability of the energy storage element 10.

[0053] [4. Other Modifications] Although the embodiment of the present invention and the modified examples thereof have been described above, the present invention is not limited to these embodiments and the modified examples. In other words, the disclosed embodiment and the modified examples are considered to be illustrative and not restrictive in all respects. The scope of the present invention is intended to include all modifications within the meaning and scope of the claims.

[0054] For example, the insulating member 141 does not need to be made of glass or crystallized glass, but may be made of, for example, a resin such as PP, PE, PPS, or PET, or a combination of an inorganic material such as glass and a resin.

[0055] The first material and the second material may be a metal or alloy other than aluminum, aluminum alloy, copper, and copper alloy, such as a metal or alloy such as nickel, stainless steel, or brass. The first material may be appropriately determined, for example, according to the material of a conductive member such as a bus bar joined to the outer end 138 of the electrode terminal 130. The second material may be appropriately determined, for example, according to the material of the current collector 300 joined to the inner end 139 of the electrode terminal 130.

[0056] In addition, the shape and size of the current collector 300 do not have to be the shape and size shown in FIG. 3 and the like. For example, it is not essential that the current collector 300 has the leg portion 320, and the current collector 300 may have, as a connection portion (electrode body connection portion) with the electrode body, an electrode body connection portion in a form corresponding to the shape, position, size, and the like of the electrode body end portion to which the electrode body connection portion is connected. For example, assume that the electrode body provided in the energy storage element 10 has a tab portion (a laminate of electrode plate tabs) at the end in the Z-axis direction. In this case, the current collector provided in the energy storage element 10 may have a terminal connection portion joined to the inner end portion 139 of the electrode terminal 130, and a flat electrode body connection portion joined to the tab portion, the thickness direction of which is arranged in a position facing the Z-axis direction like the terminal connection portion.

[0057] The energy storage element 10 may also include a plurality of electrode bodies 200. For example, when the energy storage element 10 includes two electrode bodies 200 arranged in the Y-axis direction, the current collector 300 may have four legs 320 for connection to the two electrode body ends 220.

[0058] The type of electrode body included in the energy storage element 10 is not limited to a wound type. For example, the energy storage element 10 may be provided with a laminated type electrode body in which flat electrode plates are laminated, or an electrode body having a structure in which long strip-shaped electrode plates are laminated in a bellows shape by repeatedly folding in peaks and valleys.

[0059] Furthermore, configurations constructed by arbitrarily combining the components included in the above-described embodiments and their modifications are also included within the scope of the present invention. [Industrial Applicability]

[0060] The present invention can be applied to storage elements such as lithium ion secondary batteries. [Explanation of symbols]

[0061] 10 Energy storage element 100 containers 110 Container body 111 Short side part 112 Long side part 113 Bottom wall 120 Lid 121 Opening 130, 130A, 130Aa, 130B Electrode terminal 131, 131a First conductive member 132, 132a Second conductive member 133, 133a First Materials Department 134, 134a Second material department 135 Exposed part 136 Welding 138, 138a outer end 139, 139a inner end 140 Sealing member 141 Insulating materials 142 Sealing body 150 Internal insulation plate 151 Through hole 200 Electrode body 210 Electrode body part 220 Electrode body end 300, 300A, 300B Current collector 310 Terminal connection part 311 Through hole 320 Legs

Claims

1. A container; an electrode terminal having an outer end portion located outside the wall of the container and an inner end portion located inside the wall, The electrode terminal is a first conductive member including the outer end and formed of a first material; a second conductive member including the inner end portion and having a first material portion and a second material portion joined to each other, the first material portion is formed of the first material and is joined to the first conductive member; the second material portion is formed of a second material different from the first material portion and includes the inner end portion; at least a periphery of a bonding interface between the first material portion and the second material portion in the electrode terminal is covered with an insulating member, the first material portion has an exposed portion that is not covered by the second material portion on a side of the bonding interface, The first conductive member and the first material portion are joined by a weld portion formed through the exposed portion. Energy storage element.

2. A container, an electrode terminal having an outer end portion located outside the wall of the container and an inner end portion located inside the wall, The electrode terminal is a first conductive member including the outer end and formed of a first material; a second conductive member including the inner end portion and having a first material portion and a second material portion joined to each other, the first material portion is formed of the first material and is joined to the first conductive member; the second material portion is formed of a second material different from the first material portion and includes the inner end portion; at least a periphery of a bonding interface between the first material portion and the second material portion in the electrode terminal is covered with an insulating member, The first conductive member and the first material portion are joined by a weld portion formed through a portion where the second material portion and the first material portion are overlapped. Energy storage element.

3. A container, an electrode terminal having an outer end portion located outside the wall of the container and an inner end portion located inside the wall, The electrode terminal is a first conductive member including the outer end and formed of a first material; a second conductive member including the inner end portion and having a first material portion and a second material portion joined to each other, the first material portion is formed of the first material and is joined to the first conductive member; the second material portion is formed of a second material different from the first material portion and includes the inner end portion; at least a periphery of a bonding interface between the first material portion and the second material portion in the electrode terminal is covered with an insulating member, The insulating member is formed of glass or crystallized glass. Energy storage element.

4. The second conductive member is a clad material in which the first material portion and the second material portion are roll-bonded. The energy storage element according to any one of claims 1 to 3.

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