Energy storage element

Abstract

To provide a power storage element, having a container and an electrode terminal, whose reliability has been improved.SOLUTION: A power storage element 10 comprises: an electrode terminal 130 having a shaft 131 disposed so as to penetrate an opening 121 provided on a lid 120 of a container 100; and a metal seal member 142 which seals between the shaft 131 and an opening circumferential part 122. The seal member 142 is electrically insulated from the shaft 131. The seal member 142 has a connection part 144 which is disposed to overlap the opening circumferential part 122 in the axial direction of the shaft 131 and is welded to the opening circumferential part 122 at a welding part 180. The lid 120 of the container 100 has a contact part 123. The contact part 123 is located outside a contacted part 145, which is a portion of the seal member 142, in the radial direction of the shaft 131 and comes into radial contact with the contacted part 145. The contact part 123 is located on a radially inner side than the welding part 180.SELECTED DRAWING: Figure 4A

Description

[Technical Field]

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

[0002] Patent Document 1 discloses a battery terminal having a terminal post and an insulating base with the terminal post inserted inside. A metallized layer is formed over the entire periphery of a portion of the outer periphery of the insulating base, and a ring-shaped flange made of aluminum or the like is joined to the metallized layer via a brazing material. The flange is welded to the lid of the battery container, thereby fixing the battery terminal to the battery container. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-311672 Summary of the Invention [Problem to be solved by the invention]

[0004] As in the conventional storage battery described above, a metal member such as a flange is fixed to the outer periphery of the terminal post (the shaft of the electrode terminal) via an insulating member, and the metal member is then welded to the container, thereby sealing the portion of the container through which the shaft of the electrode terminal passes (the opening) in a highly airtight manner. However, because the metal member is heated by the heat generated when welding to the container and then cooled, the metal member expands and contracts due to temperature changes. This can reduce the adhesion between the shaft of the electrode terminal and the insulating member, and / or between the insulating member and the electrode terminal. This can affect the airtightness of the seal around the shaft of the electrode terminal, potentially reducing the reliability of the energy 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 an electrode terminal having an axial body arranged to pass through an opening provided in a wall of the container, and a metal sealing member that seals between the axial body and an opening peripheral portion that is the periphery of the opening, the sealing member being electrically insulated from the axial body, the sealing member being arranged overlapping the opening peripheral portion in the axial direction of the axial body and having a connection portion welded to the opening peripheral portion at a weld portion, the wall of the container being located radially outside a contacted portion that is part of the sealing member of the axial body and having a contact portion that contacts the contacted portion in the radial direction, the contact portion being located radially inside the weld portion. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide an energy storage element including a container and electrode terminals, which has improved reliability. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view showing the appearance of an energy storage device according to an embodiment. [Figure 2] FIG. 2 is a first exploded perspective view of the energy storage device according to the embodiment. [Figure 3] FIG. 3 is a second exploded perspective view of the energy storage device according to the embodiment. [Figure 4A] FIG. 4A is a cross-sectional view showing the configuration of an electrode terminal and its surroundings according to the embodiment. [Figure 4B] FIG. 4B is a plan view showing the configuration of the electrode terminal and its surroundings according to the embodiment. [Figure 5]FIG. 5 is an enlarged cross-sectional view showing the configuration of the electrode terminal and the seal structure according to the embodiment. [Figure 6] FIG. 6 is a cross-sectional view showing the configuration of an electrode terminal and its surroundings according to the first modification of the embodiment. [Figure 7] FIG. 7 is an enlarged cross-sectional view showing a part of FIG. [Figure 8] FIG. 8 is a diagram showing a first example of the layout of convex portions and concave portions according to the first modification of the embodiment. [Figure 9] FIG. 9 is a diagram showing a second example of the layout of the convex portions and the concave portions according to the first modification of the embodiment. [Figure 10] FIG. 10 is a cross-sectional view showing the configuration of an electrode terminal and its surroundings according to the second modification of the embodiment. [Figure 11] FIG. 11 is a cross-sectional view showing the configuration of an electrode terminal and its surroundings according to another modified example of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] An energy storage element according to one embodiment of the present invention comprises an electrode terminal having an axial body arranged to pass through an opening provided in a wall of the container, and a metal sealing member that seals between the axial body and an opening peripheral portion that is the peripheral portion of the opening, the sealing member being electrically insulated from the axial body, the sealing member being arranged to overlap the opening peripheral portion in the axial direction of the axial body and having a connection portion welded to the opening peripheral portion at a weld portion, the wall of the container being located outside a contacted portion that is part of the sealing member in the radial direction of the axial body and having a contact portion that contacts the contacted portion in the radial direction, the contact portion being located inside the weld portion in the radial direction.

[0010] According to this configuration, welding a metal seal member to the periphery of the opening of the container seals the gap between the shaft and the periphery of the opening, thereby enabling the portion of the container through which the shaft penetrates (the opening) to be closed in a highly airtight manner. Furthermore, the wall of the container has a contact portion that is radially inward of the weld and radially inward of the contacted portion of the seal member, and that contacts the contacted portion. As a result, even if the portion of the seal member around the shaft attempts to displace radially due to heat generated during the formation of the weld, the contact portion of the wall is in contact with the contacted portion of the seal member, thereby suppressing this displacement. As a result, deterioration of the sealing function of the seal member around the electrode terminal (shaft) is suppressed. Thus, the energy storage device according to this embodiment is an energy storage device with improved reliability.

[0011] The radial direction of the shaft is the direction perpendicular to the central axis of the shaft and the direction across the opposing outer circumferential surfaces of the shaft on either side of the central axis. For example, "the wall of the container is located radially inward of the weld" means that the wall of the container is located closer to the central axis than the weld on a line perpendicular to the central axis of the shaft.

[0012] The sealing member may be a seal main body portion that holds the shaft at a position inside the connection portion in the radial direction, and has a seal main body portion that protrudes more toward the outside of the container than the connection portion, the contact portion being located on the inner surface of the opening peripheral portion, and the contacted portion being located on the side surface of the seal main body portion in the radial direction.

[0013] With this configuration, for example, the flange-shaped connection portion on the outer periphery of the seal body is joined to the wall of the container by a weld, and the inner surface of the opening rim contacts the outer surface of the seal body, thereby suppressing radial displacement of the seal body. In other words, with a simple shape, it is possible to suppress deterioration of the sealing function of the seal member due to heat generated when forming the weld.

[0014] One of the contact portion and the contacted portion may be located on the inner surface of a recess formed in the peripheral portion of the opening of the wall portion or the connection portion of the sealing member, and the other of the contact portion and the contacted portion may be located on the outer surface of a protrusion formed in the peripheral portion of the opening of the wall portion or the connection portion of the sealing member.

[0015] According to this configuration, for example, a protrusion provided on the connection portion of the sealing member is inserted into a recess provided on the periphery of the opening of the wall portion, thereby suppressing radial displacement of the portion of the sealing member around the shaft. Alternatively, a protrusion provided on the periphery of the opening of the wall portion is inserted into a recess provided on the connection portion of the sealing member, thereby suppressing radial displacement of the portion of the sealing member around the shaft. In either case, the portion where the protrusion is inserted into the recess is located between the connection portion and the periphery of the opening, which are aligned in the axial direction. Therefore, even if tiny metal pieces (metal contamination) are generated by inserting the protrusion into the recess, the metal contamination is unlikely to leak to the outside. This also contributes to improving the reliability of the energy storage element.

[0016] The contact portions may be formed at least at two locations facing each other across the shaft body when viewed in the axial direction.

[0017] With this configuration, the contact portions for suppressing radial displacement of the portion of the seal member around the shaft are arranged in a well-balanced manner as viewed from the axial direction, thereby improving the effect of the contact portions in suppressing partial displacement of the seal member caused by heat generated when the weld is formed.

[0018] The connection portion of the sealing member may be arranged at a position closer to the inside of the container in the axial direction than the opening periphery of the container.

[0019] According to this configuration, the connection portion of the sealing member is joined by a welded portion inside the opening periphery of the container, overlapping the opening periphery. In other words, the sealing member is structured so that the connection portion catches on the opening periphery in a direction from the inside to the outside of the container. Therefore, when the internal pressure of the container increases, the internal pressure does not act in a direction that separates the connection portion joined by the welded portion from the opening periphery, but acts in a direction that presses the connection portion against the opening periphery. In other words, the structure around the electrode terminal (shaft) of the energy storage element is highly durable against increases in the internal pressure of the container. This contributes to improving the reliability of the energy storage element.

[0020] Hereinafter, with reference to the drawings, an energy storage element according to an embodiment of the present invention (including its modified examples) will be described. Note that the embodiments described below all show comprehensive or specific examples. The numerical values, shapes, materials, components, component placement and connection configurations, manufacturing processes, and the order of manufacturing processes shown in the following embodiments are examples and are not intended to limit the present invention. Furthermore, in each drawing, dimensions and the like are not shown strictly. Furthermore, in each drawing, identical or similar components are assigned the same reference numerals. Furthermore, in each drawing, dimensions and the like are not shown strictly.

[0021] In the following description and drawings, the X-axis direction is defined as the direction in which a pair of electrode terminals (positive and negative, hereinafter the same) of an energy storage element are arranged, the direction in which a pair of current collectors are arranged, the direction of the winding axis of the electrode assembly, or the direction in which the short side surfaces of the container face each other. The Y-axis direction is defined as the direction in which the long side surfaces of the container face each other, the lateral direction of the short side surfaces of the container, or the thickness direction of the container. The Z-axis direction is defined as the direction in which the container body and lid of the energy storage element are arranged, the longitudinal direction of the short side surfaces of the container, or the direction in which the electrode assembly connection portions of the current collectors extend. The X-axis direction, Y-axis direction, and Z-axis direction intersect each other (orthogonal in this embodiment). Depending on the mode of use, the Z-axis direction may not be the up-down direction; however, for convenience of explanation, the Z-axis direction will be described below as the up-down direction.

[0022] In the following description, for example, the positive X-axis direction refers to the direction of the arrow on the X-axis, and the negative X-axis direction refers to the direction opposite to the positive X-axis direction. The same applies to the Y-axis and Z-axis directions. When simply referring to the "X-axis direction," it means either one or both directions parallel to the X-axis. The same applies to terms related to the Y-axis and Z-axis.

[0023] Furthermore, expressions indicating relative directions or attitudes, such as parallel and perpendicular, also include cases where the directions or attitudes are not strictly those. For example, "two directions are perpendicular" does not only mean that the two directions are completely perpendicular, but also means that the two directions are substantially perpendicular, i.e., that there is a difference of, for example, a few percent. In the following description, when the term "insulation" is used, it means "electrical insulation."

[0024] (Embodiment) [1. General explanation of energy storage elements] An overall description of an energy storage device 10 according to this embodiment will be given using Figures 1 and 2. Figure 1 is a perspective view showing the appearance of the energy storage device 10 according to this embodiment. Figure 2 is a first exploded perspective view of the energy storage device 10 according to this embodiment. Specifically, Figure 2 shows a state in which the container body 110 is separated from the energy storage device 10. In Figures 1 and 2, the position of a welding portion 180 that joins a sealing member 142 and a lid body 120 is schematically shown by a dotted line.

[0025] The energy storage device 10 is a secondary battery capable of charging and discharging electricity, specifically a nonaqueous electrolyte secondary battery such as a lithium-ion secondary battery. The energy storage device 10 is used, for example, as a battery for driving or starting the engine of a mobile object such as an automobile, motorcycle, personal watercraft, ship, snowmobile, agricultural machinery, construction machinery, or electric railway vehicle. Examples of the automobile include an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), and a fossil fuel (gasoline, diesel, liquefied natural gas, etc.) vehicle. Examples of the electric railway vehicle 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 device 10 can also be used as a stationary battery for home or business use.

[0026] 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 stored electricity to be used without the user having to charge it. The energy storage element 10 may also be a battery that uses a solid electrolyte. In this embodiment, the energy storage element 10 is illustrated as having a rectangular parallelepiped (cornered) 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 elongated cylindrical shape, a polygonal prism shape other than a rectangular parallelepiped shape, or the like.

[0027] As shown in FIG. 1 , the energy storage element 10 includes a container 100, negative and positive electrode terminals 130, and a seal structure 140 that seals the attachment portions of the electrode terminals 130 in the container 100. The container 100 contains an electrode assembly 200 and negative and positive current collectors 300. An electrolyte solution (non-aqueous electrolyte) is sealed inside the container 100, but is not shown. There are no particular restrictions on the type of electrolyte solution as long as it does not impair the performance of the energy storage element 10, and various types can be selected. Furthermore, spacers, insulating films, and the like (not shown) may be disposed inside the container 100.

[0028] The container 100 is a rectangular parallelepiped (square) 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 cylindrical member with a bottom that constitutes the main body of the container 100, and has short side surfaces 111 on both sides in the X-axis direction, long side surfaces 112 on both sides in the Y-axis direction, and a bottom wall 113 in the negative Z-axis direction. The short side surfaces 111 are wall portions that form the short sides of the container 100, and the long side surfaces 112 are wall portions that form the long sides of the container 100.

[0029] The lid 120 is a rectangular plate-like member that constitutes the lid portion of the container 100, and is disposed in the positive direction of the Z axis of the container body 110. In this embodiment, negative and positive electrode terminals 130 are fixed to the lid 120. The lid 120 may further be provided with a gas release valve that releases pressure when the pressure inside the container 100 increases, a liquid injection port for injecting an electrolyte solution into the container 100, and the like.

[0030] With this configuration, the container 100 is configured such that the electrode assembly 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 120 are joined by welding or the like, thereby sealing the interior. The container body 110 and the lid 120 are formed of a weldable metal, such as stainless steel, aluminum, or an aluminum alloy.

[0031] The electrode assembly 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 substrate layer, which 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 substrate layer, which is a long, strip-shaped current collector foil made of copper or a copper alloy. The current collector foil can be made of any known material, such as nickel, iron, stainless steel, titanium, baked carbon, conductive polymer, conductive glass, or an Al-Cd alloy. The positive electrode active material and negative electrode active material used in the composite layer can be any known material, as long as they are active materials capable of absorbing and releasing lithium ions. The separator can be made of, for example, a microporous resin sheet or a nonwoven fabric.

[0032] In this embodiment, the electrode assembly 200 is a wound electrode assembly in which a separator is disposed between a positive electrode plate and a negative electrode plate, and the electrode plate is wound. Specifically, the electrode assembly 200 is wound such that the positive electrode plate and the negative electrode plate are offset from each other in the direction of the winding axis (in this embodiment, a virtual axis parallel to the X-axis direction) with the separator interposed therebetween. The positive electrode plate and the negative electrode plate each have a portion (composite layer non-formed portion) at the end in the offset direction where the composite material containing the active material is not applied (no composite layer is formed) and the base material layer is exposed.

[0033] That is, the electrode body 200 has an electrode body main body 210, which is a main body portion on which a composite material layer is formed, and electrode body end portions 220 that protrude from the electrode body main body 210 in the positive and negative X-axis directions. One of these two electrode body end portions 220 is provided with a positive electrode converging portion in which composite material layer-free portions of positive electrode plates are stacked and bundled. The other electrode body end portion 220 is provided with a negative electrode converging portion in which composite material layer-free portions of negative electrode plates are stacked and bundled. Note that, although the present embodiment illustrates an electrode body 200 with an oval cross-sectional shape, the cross-sectional shape of the electrode body 200 may be circular, elliptical, or the like.

[0034] The electrode terminal 130 is a terminal electrically connected to the positive electrode plate or the negative electrode plate of the electrode assembly 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 assembly 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 assembly 200. As described above, the electrode terminal 130 is fixed to a wall (the lid 120 in this embodiment) arranged above the electrode assembly 200.

[0035] Specifically, the electrode terminal 130 has a shaft 131 disposed so as to pass through an opening 121 (see FIG. 3, which will be described later) provided in the lid 120. In the present embodiment, the electrode terminal 130 is constituted by only one shaft 131, but the configuration of the electrode terminal 130 is not limited to this. The electrode terminal 130 may have, for example, a terminal main body portion connected to the shaft 131 and disposed outside the container 100, to which a conductive member such as a bus bar is joined by welding, bolt and nut fastening, crimping, or the like. The electrode terminal 130 is formed of a metal such as aluminum, an aluminum alloy, copper, or a copper alloy.

[0036] The shaft 131 penetrates the lid 120 and is fixed to the lid 120 via the seal structure 140. That is, the seal structure 140 maintains airtightness at the portion of the wall (lid 120) of the container 100 where the shaft 131 penetrates. The end of the shaft 131 inside the container 100 (negative direction of the Z axis) is joined to the current collector 300. A conductive member (not shown), such as a bus bar, is joined to the end of the electrode terminal 130 outside the container 100 (positive direction of the Z axis). The seal structure 140 employs a structure in which a metal seal member 142 holds the shaft 131 of the electrode terminal 130 via an insulating member 141. The configuration of the electrode terminal 130 and its surroundings according to the embodiment will be described later with reference to FIGS. 3 to 5.

[0037] The current collectors 300 are members (positive electrode current collector and negative electrode current collector) arranged on both sides of the electrode assembly 200 in the X-axis direction and connected to the electrode assembly end portions 220. Specifically, a pair of legs 320 of the positive electrode current collector 300 is joined to the positive electrode assembly end portion 220, and a pair of legs 320 of the negative electrode current collector 300 is joined to the negative electrode assembly end portion 220. The current collectors 300 and the electrode assembly end portions 220 are joined by ultrasonic welding, crimping, or the like. The material of the current collectors 300 is not limited. For example, the positive electrode current collector 300 is formed of a metal such as aluminum or an aluminum alloy, similar to the positive electrode substrate layer of the electrode assembly 200. The negative electrode current collector 300 is formed of a metal such as copper or a copper alloy, similar to the negative electrode substrate layer of the electrode assembly 200.

[0038] [2. Electrode terminal and its peripheral configuration] Next, the configuration of the electrode terminals 130 and their surroundings in the energy storage device 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 surroundings of at least one of the pair of electrode terminals 130 included in the energy storage device 10. Therefore, hereinafter, of the pair of electrode terminals 130 aligned in the X-axis direction, the electrode terminal 130 in the positive X-axis direction and its surrounding configuration will be illustrated and described.

[0039] FIG. 3 is a second exploded perspective view of the energy storage device 10 according to the embodiment. In FIG. 3, the electrode terminal 130 and its peripheral components of the energy storage device 10 are shown separated. FIG. 4A is a cross-sectional view showing the configuration of the electrode terminal 130 and its peripheral components according to the embodiment. FIG. 4A is a partial cross-section of the energy storage device 10, taken along the XZ plane passing through line IV-IV in FIG. 3, and the electrode assembly 200 and the container body 110 are omitted from the illustration. FIG. 4B is a plan view showing the configuration of the electrode terminal 130 and its peripheral components according to the embodiment. In FIG. 4B, different patterns are applied to the insulating member 141 and the welding portion 180 to clearly indicate their positions. FIG. 5 is an enlarged cross-sectional view showing the configuration of the electrode terminal 130 and the seal structure 140 according to the embodiment. In FIG. 5, the components shown in FIG. 4A are exploded in the Z-axis direction and partially enlarged.

[0040] 3 to 5, the electrode terminal 130 according to this embodiment is fixed to the seal structure 140 while passing through the seal structure 140. The seal structure 140 is inserted into the opening 121 of the lid 120 and fixed to the lid 120, and the electrode terminal 130 is fixed to the container 100 while passing through the opening 121 of the lid 120. The seal structure 140 covers the outer peripheral surface of the shaft 131 of the electrode terminal 130 and includes an insulating member 141 that is electrically insulating, and a metallic sealing member 142 that is disposed along the outer periphery of the insulating member 141. In other words, the conductive sealing member 142 holds the shaft 131 via the insulating member 141, and thereby holds the shaft 131 while being electrically insulated from the shaft 131.

[0041] In the present embodiment, the insulating member 141 is, for example, a member formed of glass or crystallized glass (also referred to as glass ceramic), and is a member having electrical insulation properties and high heat resistance. The sealing member 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 lid 120 by welding it to the periphery of the opening 121 of the lid 120 (opening periphery 122). In the seal structure 140 configured as described above to hold the electrode terminal 130, the insulating member 141 is formed, for example, by sintering glass powder. As a result, a strong seal is formed between the outer circumferential surface of the shaft 131 and the seal structure 140 by the insulating member 141 integrated with the electrode terminal 130, and a strong seal is formed between the seal structure 140 and the periphery of the opening 121 of the container 100 (opening periphery 122) by welding the metals together.

[0042] As shown in Fig. 3, the end of the shaft 131 arranged in this manner, which is located inside the container 100, passes through the through hole 151 of the internal insulating plate 150 and is inserted into the through hole 311 provided in the terminal connection part 310 of the current collector 300, and is joined to the terminal connection part 310. Welding such as laser welding is used as a joining method. 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 shaft 131 may be joined by welding with the end face of the shaft 131 butted against the upper surface of the terminal connection part 310.

[0043] The internal insulating plate 150 is disposed between the lid 120 of the container 100 and the current collector 300, and is a member that provides insulation between the lid 120 and the current collector 300. The internal insulating plate 150 is formed in a substantially rectangular shape in a plan view (when viewed from the Z-axis direction) that is large enough to cover the terminal connection portion 310 of the current collector 300. The internal insulating plate 150 is formed from an electrically insulating 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), polyethersulfone (PES), polyamide (PA), ABS resin, or a composite material thereof.

[0044] In the energy storage device 10 configured in this manner, the gap between the seal structure 140 and the opening periphery 122 of the container 100 is sealed by welding as described above. The configuration of the seal structure 140 will be described in more detail below.

[0045] 4A to 5, the seal member 142 according to this embodiment is an annular member in plan view (when viewed in the positive direction of the Z axis). The seal member 142 has a seal main body 143 that holds the shaft body 131, and a connecting portion 144 that is a flange-shaped portion that protrudes from the seal main body 143 in the radial direction of the shaft body 131 (hereinafter simply referred to as the "radial direction"). The seal main body 143 is provided so as to protrude more toward the outside of the container 100 (in the positive direction of the Z axis) than the connecting portion 144.

[0046] The connection portion 144 is disposed so as to overlap an opening peripheral portion 122, which is a peripheral portion of the opening 121 of the lid 120, in the axial direction (Z-axis direction) of the shaft 131, and is welded to the opening peripheral portion 122 at a weld 180 (see FIG. 4A ). Laser welding, resistance welding, or the like is used as a method for welding the connection portion 144 of the seal member 142 to the opening peripheral portion 122. The weld 180 formed by welding the connection portion 144 to the opening peripheral portion 122 is formed in a continuous ring shape as shown in FIG. 4B . As a result, the weld 180 seals between the opening peripheral portion 122 of the lid 120 and the seal structure portion 140 around the entire circumference of the seal member 142. Although FIG. 4B illustrates the weld 180 as having an annular shape in plan view, the shape of the weld 180 in plan view does not have to be annular. The planar shape of welded portion 180 may be, for example, an elliptical, oval, polygonal, or other ring shape. There are no particular limitations on the planar shape (layout) of welded portion 180, as long as it is positioned so as to be able to join opening periphery 122 and connection portion 144 and is formed in a continuous shape that surrounds seal main body 143 (see FIG. 4A) in plan view.

[0047] In this structure, when the connection portion 144 of the seal member 142 is welded to the opening periphery 122, heat (welding heat) generated by the welding is conducted to the seal structure 140. In this case, the welding heat causes the metal seal member 142 to expand and contract. As a result, for example, the portion of the seal main body 143 around the shaft 131 tends to displace radially. For example, the portion of the seal main body 143 shown in FIG. 5 tends to displace in the negative direction of the X-axis. As a result, the adhesion between the insulating member 141 and the seal main body 143 and / or the insulating member 141 and the shaft 131, which are interfaces between members made of different materials, may be reduced. This may result in a decrease in the sealing function of the seal member 142 around the electrode terminal 130.

[0048] Therefore, energy storage device 10 according to the present embodiment employs a configuration that suppresses deterioration of the sealing function of seal member 142 due to welding heat. Specifically, energy storage device 10 according to the present embodiment arranges seal member 142 and lid body 120 so as to come into contact with each other in the radial direction of shaft body 131.

[0049] 4A to 5, the cover 120 has a contact portion 123 located on the inner circumferential surface of the opening rim portion 122, and the seal member 142 has a contacted portion 145 located on the outer circumferential surface of the seal main body portion 143. In the radial direction of the shaft 131, the contact portion 123 is located outside the contacted portion 145 and is in contact with the contacted portion 145. The contact portion 123 is located radially inward of the welded portion 180 (at a position closer to the shaft 131). In other words, as shown in FIGS. 4A and 4B, the contact portion 123 and the contacted portion 145 are in contact with each other radially inward of the welded portion 180, which is the portion that secures the seal member 142 to the cover 120. Furthermore, in the radial direction of the shaft 131, the contacted portion 145 located inside the opening periphery 122 of the lid 120 is in contact with the contact portion 123 located outside it (at a position farther from the shaft 131). As a result, the radial movement of the contacted portion 145 is restricted by the contact portion 123. Therefore, a decrease in the adhesion between the insulating member 141 and the shaft 131 caused by the expansion and contraction of the seal main body 143 of the seal member 142 due to welding heat is suppressed.

[0050] The radial direction of shaft body 131 is a direction perpendicular to the central axis of shaft body 131 and refers to the span between opposing outer circumferential surfaces of shaft body 131 on either side of the central axis. For example, "contact portion 123 of lid body 120 is located radially inward of welded portion 180" means that, on a line perpendicular to the central axis of shaft body 131, contact portion 123 is located closer to the central axis than welded portion 180. In this embodiment, shaft body 131 is cylindrical, meaning that the cross section perpendicular to the axial direction is circular. However, the shape of shaft body 131 is not particularly limited. For example, a shaft having a cross section perpendicular to the axial direction that is polygonal, elliptical, or the like may be used as shaft body 131 included in energy storage device 10. In this case, too, the radial direction of shaft body 131 is a direction perpendicular to the central axis of shaft body 131 and refers to the span between opposing outer circumferential surfaces of shaft body 131 on either side of the central axis.

[0051] One method for bringing the contact portion 123 of the opening periphery 122 of the lid 120 into contact with the contacted portion 145 of the seal member 142 is, for example, pressurization. Specifically, the seal member 142 is inserted under pressure into the opening 121, which has an inner diameter slightly smaller than the outer diameter of the seal body 143 in a plan view. In this case, the seal member 142 can be temporarily fixed to the opening 121 before welding the connection portion 144 of the seal member 142 to the opening periphery 122. This facilitates welding the connection portion 144 to the opening periphery 122. When the seal member 142 is pressurized into the opening 121, the entire circumferential area of ​​the seal body 143 generally comes into contact with the opening periphery 122. In other words, the contact portion 123 and the contacted portion 145 are present along the entire boundary between the seal body 143 and the opening periphery 122, which is annular in a plan view. However, it is not essential that the contact portion 123 and the contacted portion 145 be present along the entire boundary between the seal body 143 and the opening periphery 122, which is annular in plan view. For example, the seal body 143 and the opening 121 may be fitted together in a manner generally referred to as a transition fit, where a gap is formed between adjacent components due to component tolerances. In other words, the contact portion 123 and the contacted portion 145, which are in radial contact, may be present only along a portion of the annular boundary in plan view. Even in this case, radial displacement of the portion of the seal member 142 around the shaft 131 is suppressed, at least on the radial line where the contact portion 123 and the contacted portion 145 are aligned. This contributes to suppressing deterioration of the sealing function of the seal member 142.

[0052] As described above, energy storage device 10 according to the present embodiment includes electrode terminal 130 having shaft 131 disposed to pass through opening 121 provided in lid 120 of container 100, and metal seal member 142 that seals between shaft 131 and opening periphery 122. Seal member 142 is electrically insulated from shaft 131. Seal member 142 is disposed to overlap opening periphery 122 in the axial direction of shaft 131 and has connection portion 144 welded to opening periphery 122 at welded portion 180. Lid 120 of container 100 has contact portion 123. Contact portion 123 is located radially outward of contacted portion 145, which is part of seal member 142, of shaft 131 and is in radial contact with contacted portion 145. Contact portion 123 is located radially inward of welded portion 180.

[0053] As described above, in this embodiment, the metal seal member 142 is welded to the opening periphery 122 of the container 100, thereby sealing the shaft 131 and the opening periphery 122. This allows the portion of the container 100 through which the shaft 131 passes (opening 121) to be closed in a highly airtight manner. Furthermore, the lid 120 of the container 100 has a contact portion 123 that is in radial contact with the contact portion 145 of the seal member 142, located radially inward of the weld portion 180 and outside the contact portion 145 of the seal member 142. This prevents the contact portion 123 of the lid 120 from contacting the contact portion 145 of the seal member 142, even if the portion of the seal member 142 around the shaft 131 tends to be displaced radially due to heat generated when the weld portion 180 is formed. This prevents the displacement of the contact portion 123 of the lid 120 from contacting the contact portion 145 of the seal member 142. As a result, a decrease in the sealing function of the seal member 142 around the shaft 131 is suppressed. Thus, energy storage device 10 according to this embodiment is an energy storage device with improved reliability.

[0054] 4A and 5, in this embodiment, contact portion 123 and contacted portion 145 are in contact with each other on a surface perpendicular to the radial direction, but this is not essential. However, from the viewpoint of maintaining or improving the effect of suppressing partial displacement of seal member 142, it is preferable that contact portion 123 and contacted portion 145 be in contact with each other on a surface perpendicular to the radial direction.

[0055] In this embodiment, seal member 142 has seal main body 143 that holds shaft 131, located radially inside connecting portion 144. As shown in Figures 4A and 5, seal main body 143 has a shape that protrudes further toward the outside of container 100 than connecting portion 144. Contact portion 123 is located on the inner circumferential surface of opening periphery 122, and contacted portion 145 is located on the side surface of seal main body 143 in the radial direction.

[0056] As described above, in this embodiment, flange-shaped connecting portion 144 on the outer periphery of seal main body 143 is joined to lid 120 of container 100 by weld 180. Furthermore, the inner circumferential surface of opening rim 122 comes into contact with the outer surface of seal main body 143, thereby suppressing radial displacement of the portion of seal main body 143 around shaft 131. In other words, a simple shape can be used to suppress deterioration of the sealing function of seal member 142 caused by heat generated when weld 180 is formed.

[0057] In this embodiment, contact portions 123 are formed at least at two locations facing each other across shaft body 131 when viewed in the axial direction of shaft body 131. This allows contact portions 123, which suppress radial displacement of the portion of seal member 142 around shaft body 131, to be arranged in a balanced manner when viewed in the axial direction. As a result, the effect of contact portions 123 in suppressing deformation of seal member 142 caused by heat when welded joint 180 is improved.

[0058] More specifically, in this embodiment, as described above, contact portion 123 and contacted portion 145 are annular boundary portions in a plan view, and exist along the entire boundary portion between seal main body 143 and opening circumferential portion 122. In other words, contact portion 123 and contacted portion 145 that contacts it are formed at two arbitrarily selected locations that face each other across shaft body 131 when viewed from the axial direction of shaft 131. This suppresses radial deformation of seal member 142 over the entire boundary portion, and as a result, seal member 142 more reliably performs its sealing function around shaft body 131.

[0059] It is not essential that the contact portion 123 and the contacted portion 145 are present along the entire boundary between the seal body 143 and the opening periphery 122. For example, if the contact portion 123 and the contacted portion 145 that come into contact with each other in the radial direction are arranged at least in two locations that face each other across the shaft 131, it is possible to improve the effect of suppressing radial deformation of the seal member 142. This also applies to Modifications 1 and 2 described below.

[0060] In this embodiment, connection portion 144 of sealing member 142 is located at a position closer to the inside of container 100 than opening periphery 122 of container 100 in the axial direction of shaft body 131. In other words, when energy storage device 10 is oriented with lid body 120 facing upward, connection portion 144 of sealing member 142 is located below opening periphery 122.

[0061] According to this configuration, the connection portion 144 of the seal member 142 is joined by the welded portion 180 in a state overlapping the opening peripheral portion 122 inside (in the negative Z-axis direction) of the opening peripheral portion 122 of the container 100. That is, the seal member 142 is structured so that the connection portion 144 is caught on the opening peripheral portion 122 in a direction from the inside to the outside of the container 100. Therefore, when the internal pressure of the container 100 increases, the internal pressure does not act in a direction that separates the connection portion 144 and the opening peripheral portion 122, which are joined by the welded portion 180, but acts in a direction that presses the connection portion 144 against the opening peripheral portion 122. That is, the structure around the shaft 131 of the energy storage device 10 has high durability against an increase in the internal pressure of the container 100. This contributes to improving the reliability of the energy storage device.

[0062] The energy storage device 10 according to the embodiment of the present invention has been described above, but the energy storage device 10 may have a seal structure portion having a configuration different from the seal structure portion 140 shown in Figures 1 to 5. Therefore, modified examples of the seal structure portion 140 will be described below, focusing on the differences from the above embodiment.

[0063] [3-1. Variation 1] FIG. 6 is a cross-sectional view showing an electrode terminal 130 and its surrounding structure according to a first modification of the embodiment. The position of the cross section in FIG. 6 corresponds to the position of the cross section in FIG. 4A, and the electrode body 200 and the container body 110 are not shown. FIG. 7 is an enlarged cross-sectional view showing a portion of FIG. 6. FIG. 8 is a diagram showing a first example of the layout of the protrusions 146 and the recesses 126 according to the first modification of the embodiment, and FIG. 9 is a diagram showing a second example of the layout of the protrusions 146 and the recesses 126 according to the first modification of the embodiment. In FIGS. 8 and 9, different types of patterns are applied to the insulating member 141 and the welding portion 180 to clearly show the positions of the insulating member 141 and the welding portion 180, and the placement areas of the protrusions 146 and the recesses 126 are indicated by dashed lines.

[0064] Energy storage device 10a according to this modification includes electrode terminal 130 having shaft 131 disposed to pass through opening 121 provided in lid 120a of container 100, and metal seal member 142 that seals between shaft 131 and opening periphery 122a. Seal member 142 is electrically insulated from shaft 131. Seal member 142 is disposed to overlap opening periphery 122a in the axial direction of shaft 131 and has connection portion 144a welded to opening periphery 122a at weld portion 180. Lid 120a of container 100 has contact portion 123. Contact portion 123 is located radially outward of contacted portion 145 (see FIG. 7 ), which is part of seal member 142, and is in radial contact with contacted portion 145. Contact portion 123 is located radially inward of welded portion 180. These configurations are common to energy storage device 10 according to the embodiment. Therefore, according to energy storage device 10a according to this modification, like energy storage device 10 according to the embodiment, it is possible to suppress deterioration of the sealing function of seal member 142 around shaft body 131.

[0065] In this modified example, the positions of the contact portion 123 and the contacted portion 145 differ from those of the above embodiment. Specifically, as shown in Figures 6 and 7, the contact portion 123 is located on the inner surface of a recess 126 formed in the opening periphery 122a of the lid 120a. The contacted portion 145 is located on the outer surface of a protrusion 146 formed in the connection portion 144a of the seal member 142. For example, in Figure 7, the contact portion 123 is located on the inner surface of the recess 126 in the negative X-axis direction, and the contacted portion 145 is located on the outer surface of the protrusion 146 in the negative X-axis direction.

[0066] In this manner, in this modification, the projection 146 provided on the connection portion 144a of the seal member 142 is inserted into the recess 126 provided in the opening periphery 122a of the lid 120a, thereby suppressing radial displacement of the portion of the seal member 142 around the shaft 131. Furthermore, as shown in FIG. 7, the portion where the projection 146 is inserted into the recess 126 is located between the connection portion 144a and the opening periphery 122a, which are aligned in the axial direction of the shaft 131. Therefore, even if minute metal pieces (metal contamination) are generated by inserting the projection 146 into the recess 126, the metal contamination is unlikely to leak to the outside. This also contributes to improving the reliability of the energy storage element 10a.

[0067] In this modification, the protrusion 146 is inserted under pressure into the recess 126, which has a radial width slightly smaller than that of the protrusion 146. That is, the protrusion 146 is press-fitted into the recess 126. This allows the radially outer surface of the protrusion 146 to be more reliably in contact with the radially inner surface of the recess 126. Furthermore, for example, before forming the weld 180, the seal member 142 can be temporarily fixed to the opening 121. This facilitates welding of the connection portion 144a and the opening periphery 122a. It is not necessary to press-fit the protrusion 146 into the recess 126. As long as the radially outer outer surface of the protrusion 146 and the radially inner inner surface of the recess 126 are in contact with each other, gaps may be formed between the outer surface of the protrusion 146 and the inner surface of the recess 126 in other areas. The protrusion 146 does not have to be inserted into the entire recess 126 in the depth direction (Z-axis direction). For example, to ensure close contact between connecting portion 144a and opening periphery 122a, the length of protrusion 146 in the Z-axis direction may be shorter than the depth of recess 126. In this case, a gap may exist between the tip of protrusion 146 and the bottom surface of recess 126.

[0068] In this modification, unlike the above embodiment, the outer surface of the seal body 143 and the inner circumferential surface of the opening periphery 122a do not need to contact each other. Therefore, a gap (see FIG. 7 ) may exist between the outer surface of the seal body 143 and the inner circumferential surface of the opening periphery 122a along the entire circumference of the inner circumferential surface. For example, the inner diameter of the opening 121 may be made relatively large for the seal body 143, whose position relative to the lid 120a is determined by inserting the protrusion 146 into the recess 126. This may allow the protrusion 146 to be inserted into both the recess 126 and the seal body 143 to be inserted into the opening 121. As a result, a gap may exist between the outer surface of the seal body 143 and the inner circumferential surface of the opening periphery 122a. Furthermore, in this modification, it is not essential that a gap exist between the outer surface of the seal body 143 and the inner circumferential surface of the opening periphery 122a. The outer surface of the seal body 143 and the inner circumferential surface of the opening rim 122a may be in contact with each other over the entire circumference or a portion of the inner circumferential surface.

[0069] 8, the protrusions 146 and the recesses 126 may be arranged to form a continuous ring shape. This suppresses radial displacement of the portion of the seal member 142 around the shaft body 131 over the entire circumferential area of ​​the seal member 142. As a result, the seal member 142 can more reliably perform its sealing function around the shaft body 131.

[0070] 9, the convex portions 146 and the concave portions 126 may be arranged intermittently (dispersed) along the circumferential direction of the seal member 142. Even in this case, radial displacement of the portion of the seal member 142 around the shaft body 131 is suppressed at least on the straight line along which the convex portions 146 and the concave portions 126 exist in the radial direction. This contributes to suppressing deterioration of the sealing function of the seal member 142.

[0071] In this modified example, as in the above embodiment, if a contact portion 123 and a contacted portion 145 that contact each other radially are arranged at least in two locations opposite each other across the shaft body 131, the effect of suppressing radial deformation of the sealing member 142 can be improved.

[0072] Furthermore, in this modification, the connection portion 144a of the seal member 142 is overlapped with the opening peripheral portion 122a inside (negative Z-axis direction) of the container 100 and joined by the welded portion 180. Therefore, like the energy storage device 10 according to the above embodiment, the structure around the shaft 131 of the energy storage device 10a has high durability against an increase in the internal pressure of the container 100. This contributes to improving the reliability of the energy storage device 10a.

[0073] In this modification, the connecting portion 144a of the sealing member 142 is positioned closer to the interior of the container 100 than the opening periphery 122a of the container 100 in the axial direction of the shaft 131. However, the positional relationship between the connecting portion 144a and the opening periphery 122a in the axial direction of the shaft 131 (the Z-axis direction) may be reversed. In this case, the protrusion 146 may be provided to protrude from the connecting portion 144a in the negative Z-axis direction, and the recess 126 may be provided to be recessed in the negative Z-axis direction in the connecting portion 144a. Even in this case, the protrusion 146 of the connecting portion 144a can be inserted into the recess 126 of the opening periphery 122a, thereby bringing the contact portion 123 and the contacted portion 145 into radial contact. As a result, deterioration of the sealing function of the sealing member 142 around the shaft 131 can be suppressed.

[0074] [3-2. Variation 2] In the above-described first modification, the convex portion 146 is arranged on the connecting portion 144a of the sealing member 142, and the concave portion 126 is arranged on the opening periphery 122a of the lid 120a. However, the positions of the convex portion and the concave portion may be reversed to prevent deterioration of the sealing function. Therefore, a structure in which the concave portion 147 is arranged on the connecting portion 144b, and the convex portion 127 is arranged on the opening periphery 122b will be described below as a second modification.

[0075] 10 is a cross-sectional view showing the configuration of an electrode terminal 130 and its surroundings according to Modification 2 of the embodiment. In Fig. 10, the position of the cross section corresponds to the position of the cross section in Fig. 4A, and the display range corresponds to the enlarged cross-sectional view in Fig. 7.

[0076] As shown in FIG. 10 , in energy storage device 10b according to this modification, sealing member 142 is disposed so as to overlap opening periphery 122b in the axial direction of shaft body 131, and has connection portion 144b welded to opening periphery 122b at welded portion 180. Cover 120b of container 100 is located outside contacted portion 145, which is part of sealing member 142, in the radial direction of shaft body 131, and has contact portion 123 that contacts contacted portion 145 in the radial direction. Contact portion 123 is located radially inward of welded portion 180. These configurations are common to energy storage device 10 according to the embodiment. Therefore, according to energy storage device 10b according to this modification, like energy storage device 10 according to the embodiment, it is possible to suppress a decrease in the sealing function of sealing member 142 around shaft body 131.

[0077] In this modification, the positions of contact portion 123 and contacted portion 145 differ from those of the above-described embodiment and modification 1. Specifically, as shown in Fig. 10, contacted portion 145 is located on the inner surface of recess 147 formed in connecting portion 144b of seal member 142. Contact portion 123 is located on the outer surface of protrusion 127 formed on opening periphery 122b of lid 120b. For example, in Fig. 10, contacted portion 145 is located on the inner surface of recess 147 in the positive direction of the X axis, and contact portion 123 is located on the outer surface of protrusion 127 in the positive direction of the X axis.

[0078] In this modified example, convex portion 127 provided on opening periphery 122b of lid 120b is inserted into concave portion 147 provided on connecting portion 144b of seal member 142, thereby suppressing radial displacement of the portion of seal member 142 around shaft 131. Furthermore, as shown in FIG. 10 , the portion where convex portion 127 is inserted into concave portion 147 is located between connecting portion 144b and opening periphery 122b, which are aligned in the axial direction of shaft 131. Therefore, even if tiny metal pieces (metal contamination) are generated by inserting convex portion 127 into concave portion 147, the metal contamination is unlikely to leak to the outside. This also contributes to improving the reliability of energy storage element 10b.

[0079] In this modified example, the protrusions 127 may or may not be press-fitted into the recesses 147. As long as the outer surfaces of the protrusions 127 facing radially inward come into contact with the inner surfaces of the recesses 147 facing radially outward, gaps may be formed between the outer surfaces of the protrusions 127 and the inner surfaces of the recesses 147 in other portions. The protrusions 127 do not have to be inserted over the entire depth direction (Z-axis direction) of the recesses 147. In other words, a gap may exist between the tip of the protrusions 127 and the bottom surface of the recesses 147.

[0080] In addition, as in the above-mentioned variant example 1, there may be a gap between the outer surface of the seal main body portion 143 and the inner surface of the opening peripheral portion 122b, and they may be in contact around the entire circumference or part of the inner surface.

[0081] Furthermore, the positions of the protrusions 127 and the recesses 147 may be arranged to form a continuous ring, for example, similar to the positions of the protrusions 146 and the recesses 126 shown in Fig. 8. The protrusions 127 and the recesses 147 may be arranged discontinuously (dispersed) along the circumferential direction of the seal member 142, for example, similar to the positions of the protrusions 146 and the recesses 126 shown in Fig. 9.

[0082] In this modification, the connection portion 144b of the sealing member 142 is disposed inside (in the negative Z-axis direction) the opening periphery 122b of the container 100. Therefore, the effects of this structure (such as high durability against an increase in the internal pressure of the container 100) are also achieved in the same way as in the above embodiment and modification 1.

[0083] In this modification, the connecting portion 144b of the sealing member 142 is positioned closer to the interior of the container 100 than the opening periphery 122b of the container 100 in the axial direction of the shaft 131. However, the positional relationship between the connecting portion 144b and the opening periphery 122b in the axial direction of the shaft 131 (the Z-axis direction) may be reversed. In this case, the protrusion 123 is provided to protrude from the opening periphery 122b in the positive Z-axis direction, and the recess 147 is provided to be recessed in the connecting portion 144b in the positive Z-axis direction. Even in this case, the protrusion 127 of the opening periphery 122b can be inserted into the recess 147 of the connecting portion 144b, thereby bringing the contact portion 123 into contact with the contacted portion 145 in the radial direction. As a result, deterioration of the sealing function of the sealing member 142 around the shaft 131 can be suppressed.

[0084] The convex portions 123 and the concave portions 147 may be arranged to form a continuous ring, for example, similar to the convex portions 146 and the concave portions 126 shown in FIG. 8, or may be arranged intermittently (dispersed) along the circumferential direction of the sealing member 142, similar to the convex portions 146 and the concave portions 126 shown in FIG. 9.

[0085] [4. Other Modifications] Although the energy storage element according to the embodiment and its modification of the present invention has been described above, the present invention is not limited to this embodiment and its modification. In other words, the embodiment and its modification disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is intended to include all modifications within the meaning and scope of the claims.

[0086] For example, the wall of container 100 on which electrode terminal 130 is arranged does not have to be lid 120. Electrode terminal 130 may be arranged on a wall (another wall) of container 100 other than lid 120, such as bottom wall 113 of container body 110. That is, shaft 131 held by seal member 142 may be arranged in an opening provided in the other wall. Even in this case, the opening through which shaft 131 is arranged can be sealed with high airtightness by seal member 142.

[0087] 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.

[0088] The shape of the seal member 142 when viewed in the axial direction of the shaft body 131 does not have to be circular as shown in Figures 3 and 4B. The shape of the seal member 142 may be other shapes such as an elliptical ring or a polygonal ring.

[0089] Although contact portion 123 in the embodiment is provided over the entire area in the Z-axis direction on the end face of opening periphery 122, as shown in Fig. 5, contact portion 123 may be provided over only a portion of the end face in the Z-axis direction. For example, the portion of the end face other than contact portion 123 may be an inclined surface portion 123a that is not perpendicular to the radial direction of shaft body 131 (inclined with respect to the axial direction of shaft body 131), as shown in Fig. 11.

[0090] Fig. 11 is a cross-sectional view showing an electrode terminal 130 and its surrounding structure according to another modified example of the embodiment. The position of the cross section in Fig. 11 corresponds to the position of the cross section in Fig. 4A. In energy storage element 10c shown in Fig. 11, an inclined surface portion 123a is provided at the end of the end face of opening periphery 122 (the inner circumferential surface of opening 121) close to the inside of container 100. In other words, inclined surface portion 123a is provided in the negative Z-axis direction of contact portion 123. Inclined surface portion 123a forms a surface that is inclined radially outward as it approaches the inside of container 100.

[0091] 5, when seal structure 140 including seal member 142 is inserted into opening 121 of lid 120, inclined surface 123 functions as a guide that guides seal body 143 of seal member 142 into opening 121. This makes it easier to press seal body 143 into opening 121, for example.

[0092] In the above description, the contact portion 123 and the inclined surface portion 123a are distinguished from each other, but the inclined surface portion 123a may be a part of the contact portion 120. In this case, the contact portion 123 can be described as having a surface perpendicular to the radial direction and a surface (inclined surface portion 123a) that is not perpendicular to the radial direction, and at least the surface perpendicular to the radial direction comes into contact with the contacted portion 145.

[0093] Although the cross-sectional shapes of the protrusion 146 and the recess 126 according to the first modification are both rectangular (see FIG. 7 ), these cross-sectional shapes are not particularly limited. The cross-sectional shapes of the protrusion 146 and the recess 126 may be, for example, polygonal, with some corners cut off or rounded. That is, an inclined surface may be provided at the tip of the protrusion 146 in the protruding direction to facilitate insertion into the recess 126. An inclined surface may be provided at the periphery of the opening of the recess 126 to guide the protrusion 146 into the recess 126. In this way, providing an inclined surface on at least one of the protrusion 146 and the recess 126 makes it easier to insert the protrusion 146 into the recess 126. Furthermore, the generation of minute metal pieces (metal contamination) due to interference between the tip of the protrusion 146 and the periphery of the opening of the recess 126 during insertion of the protrusion 146 into the recess 126 is suppressed. The cross-sectional shapes of the convex portion 146 and the concave portion 126 may both be triangular or semicircular. Furthermore, the cross-sectional shapes of the convex portion 146 and the concave portion 126 may be different from each other. For example, a convex portion 146 having a triangular or semicircular cross-sectional shape may be inserted into a concave portion 126 having a rectangular cross-sectional shape (see FIG. 7 ). However, in order to avoid reducing the effect of suppressing partial displacement of the seal member 142 due to contact between the contact portion 123 and the contacted portion 145, it is preferable that the contact portion 123 and the contacted portion 145 contact each other on a surface perpendicular to the radial direction. Therefore, regardless of whether the cross-sectional shapes of the convex portion 146 and the concave portion 126 are the same or not, it is preferable that the contact portion 123 and the contacted portion 145 each have a shape that forms a surface perpendicular to the radial direction, as shown in FIG. 7 . These supplementary notes regarding the cross-sectional shapes of the convex portion 146 and the concave portion 126 also apply to the convex portion 127 and the concave portion 147 according to Modification 2.

[0094] In the first modification, it is not essential that the contact portion 123 and the contacted portion 145, which are in radial contact with each other, are arranged at two opposing positions across the shaft 131. For example, as shown in FIG. 9 , when a plurality of pairs of protrusions 146 and recesses 126 are dispersedly arranged on the radially inner side of the welded portion 180, three pairs of protrusions 146 and recesses 126 may be arranged at equal intervals around the circumference of the shaft 131. In this case, the positions of the three pairs of protrusions 146 and recesses 126 facing each other across the shaft 131 are not occupied by other pairs of protrusions 146 and recesses 126. In other words, when focusing on the contact portion 123 of a certain recess 126, it is not necessary that another contact portion 123 be arranged at a position facing the contact portion 123 across the shaft 131. Even in this case, the effect of suppressing deformation of seal member 142 caused by heat during formation of welded joint 180 is achieved by each of one or more contact portions 123 being in contact with contacted portion 145 corresponding to said contact portion 123. The supplementary notes regarding the arrangement positions of these convex portions 146 and concave portions 126 also apply to convex portions 127 and concave portions 147 according to Modification 2.

[0095] The layout (arrangement shape) of the convex portions 146 and the concave portions 126 according to the first modification in plan view does not have to be the annular or curved shape shown in Figures 8 and 9. For example, the convex portions 146 and the concave portions 126 may be arranged in a polygonal ring shape such as a rectangle in plan view. For example, multiple pairs of convex portions 146 and concave portions 126 arranged in an annular shape in plan view may be arranged concentrically inside the welded portion 180. The supplementary notes regarding the layout (arrangement shape) of these convex portions 146 and concave portions 126 in plan view also apply to the convex portions 127 and concave portions 147 according to the second modification.

[0096] The shape and size of the current collector 300 do not necessarily 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 have the leg portion 320. The current collector 300 may have, as a connection portion with the electrode assembly (electrode assembly connection portion), an electrode assembly connection portion of a configuration that corresponds to the shape, position, size, etc. of the electrode assembly end portion to which the electrode assembly connection portion is connected. For example, assume that the electrode assembly included in the energy storage element 10 has a tab portion (a stack of electrode plate tabs) at the end in the Z-axis direction. In this case, the current collector included in the energy storage element 10 may have a terminal connection portion that is joined to the end of the electrode terminal 130, and a flat electrode assembly connection portion that is joined to the tab portion and is arranged with its thickness direction facing the Z-axis direction, the same as the terminal connection portion.

[0097] The energy storage element 10 may include multiple electrode bodies 200. For example, if 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 connecting to the two electrode body ends 220.

[0098] The type of electrode body 200 included in the energy storage device 10 is not limited to the wound type. For example, a laminated electrode body in which flat electrode plates are stacked, or an electrode body having a structure in which long strip-shaped electrode plates are stacked in an accordion-like shape by repeatedly folding in peaks and valleys, may be adopted as the electrode body 200 included in the energy storage device 10.

[0099] 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]

[0100] The present invention can be applied to an electric storage element such as a lithium ion secondary battery. [Explanation of symbols]

[0101] 10, 10a, 10b Storage element 100 containers 120, 120a, 120b lid body 121 Opening 122, 122a, 122b Opening periphery 123 Contact part 126, 147 recesses 127, 146 convex part 130 Electrode terminal 131 Axial body 140 Seal structure 141 Insulating materials 142 Sealing material 143 Seal body 144, 144a, 144b connection parts 145 Contacted part 180 Welded Section

Claims

1. A container and an electrode terminal having a shaft disposed through an opening in a wall of the container; a metal seal member that seals between the shaft body and an opening peripheral portion that is a peripheral portion of the opening, the seal member being electrically insulated from the shaft body; the seal member has a connection portion that is disposed so as to overlap the opening peripheral portion in the axial direction of the shaft body and is welded to the opening peripheral portion at a weld portion, the wall portion of the container has a contact portion that is located outside a contacted portion that is a part of the seal member in a radial direction of the shaft and that contacts the contacted portion in the radial direction, the contact portion is located radially inward of the weld portion, one of the contacting portion and the contacted portion is located on the periphery of the opening of the wall portion or on an inner surface of a recess formed in the connecting portion of the sealing member, the other of the contact portion and the contacted portion is located on the outer surface of a protrusion formed on the periphery of the opening of the wall portion or the connecting portion of the sealing member. Energy storage element.

2. The contact portions are formed at least at two locations facing each other across the shaft body when viewed from the axial direction. The energy storage element according to claim 1 .

3. The connection portion of the sealing member is disposed at a position closer to the inside of the container than the opening peripheral portion of the container in the axial direction. The energy storage element according to claim 1 or 2.

Images