Energy storage element

Abstract

To provide a power storage element in which sealability around a shaft body of an electrode terminal is improved.SOLUTION: A power storage element 10 includes: a container 100; an electrode terminal 200; an upper insulation member 300; a first seal member 70; and a second seal member 80. The electrode terminal 200 has a terminal body 201 and a shaft body 210. The upper insulation member 300 is disposed between the terminal body 201 and a lid body 120 of the container 100. The first seal member 70 is disposed between the terminal body 201 and the upper insulation member 300. The second seal member 80 is disposed between the upper insulation member 300 and the lid body 120. The upper insulation member 300 has a first housing part 310 which forms a space for housing a part of the first seal member 70 as seen in an axial direction of the shaft body 210. The lid body 120 has a second housing part 125 which forms a space for housing a part of the second seal member 80 as seen in the axial direction.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to an energy storage element including a container and an electrode terminal having a shaft that penetrates a wall of the container. [Background technology]

[0002] Patent Document 1 discloses a terminal structure for a non-aqueous electrolyte secondary battery. This terminal structure includes a lid for a battery case, a protrusion penetrating the lid, an insulator, and a gasket. The gasket is located between the inner surface of the lid and the second lead portion, and to the side of the protrusion of the insulator. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-181544 Summary of the Invention [Problem to be solved by the invention]

[0004] In the conventional nonaqueous electrolyte secondary battery (energy storage element) described above, the electrode terminal is fixed to the battery case (container) with the protruding portion (the shaft of the electrode terminal) passing through the lid member of the case, and a gasket (sealing member) in the form of an O-ring is disposed around the shaft. In this energy storage element, the sealing member prevents the electrolyte from leaking out of the case. However, in the conventional energy storage element described above, the sealing member is disposed along the inner surface of the lid member of the container. Therefore, for example, if water infiltrates from around the terminal body of the electrode terminal (the portion disposed outside the container) toward the shaft, the sealing member located inside the container cannot prevent the water from reaching the shaft.

[0005] The present invention was made by the inventor of the present application with a new focus on the above-mentioned problem, and aims to provide an energy storage element with improved sealing around the shaft body of the electrode terminal, and a method for manufacturing the same. [Means for solving the problem]

[0006] An energy storage element according to one aspect of the present invention is an energy storage element having a container, the energy storage element comprising: a terminal body arranged outside the container; an electrode terminal connected to the terminal body and having a shaft arranged to penetrate a wall of the container; an insulating member arranged between the terminal body and the wall of the container; a first seal member arranged between the terminal body and the insulating member and extending circumferentially around the shaft and separate from the terminal body and the insulating member; and a second seal member arranged between the insulating member and the wall of the container and extending circumferentially around the shaft and separate from the insulating member and the wall, the insulating member having a first accommodating portion that forms a space to accommodate at least a portion of the first seal member in the axial direction of the shaft; and the wall having a second accommodating portion that forms a space to accommodate at least a portion of the second seal member in the axial direction. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide an energy storage device in which the sealing performance around the shaft body of the electrode terminal is improved. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a perspective view showing the appearance of an energy storage element according to an embodiment; [Figure 2] FIG. 2 is an exploded perspective view of the energy storage element according to the embodiment. [Figure 3] FIG. 2 is an exploded perspective view showing the configuration of an electrode terminal and its surroundings according to the embodiment. [Figure 4A] 1 is a first cross-sectional view showing the configuration of an electrode terminal and its surroundings according to an embodiment. [Figure 4B] FIG. 4 is a plan view showing the positional relationship between a first seal member and a second seal member according to the embodiment. [Figure 5] FIG. 4 is a second cross-sectional view showing the configuration of the electrode terminal and its surroundings according to the embodiment. [Figure 6]FIG. 10 is a cross-sectional view showing the configuration of an electrode terminal and its surroundings according to a first modified example of the embodiment. [Figure 7] FIG. 10 is a perspective view showing the appearance of a second housing section according to a first modified example of the embodiment. [Figure 8] 10 is a first cross-sectional view showing the configuration of an electrode terminal and its surroundings according to a second modification of the embodiment. FIG. [Figure 9] FIG. 10 is a second cross-sectional view showing the configuration of an electrode terminal and its surroundings according to the second modification of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] An energy storage element according to one aspect of the present invention is an energy storage element having a container, the energy storage element comprising: a terminal body arranged outside the container; an electrode terminal connected to the terminal body and having a shaft arranged to penetrate a wall of the container; an insulating member arranged between the terminal body and the wall of the container; a first seal member arranged between the terminal body and the insulating member and extending circumferentially around the shaft and separate from the terminal body and the insulating member; and a second seal member arranged between the insulating member and the wall of the container and extending circumferentially around the shaft and separate from the insulating member and the wall, the insulating member having a first accommodating portion that forms a space to accommodate at least a portion of the first seal member in the axial direction of the shaft; and the wall having a second accommodating portion that forms a space to accommodate at least a portion of the second seal member in the axial direction.

[0010] According to this configuration, the first and second sealing members (two sealing members) are disposed on opposite sides of the insulating member outside the container. This reduces the possibility of liquid (such as water) outside the container reaching the shaft. For example, when assembling the energy storage device with the terminal body positioned above the wall, the first sealing member can be placed in the first housing portion of the insulating member, and the second sealing member can be placed in the second housing portion of the wall. This allows efficient assembly with these two sealing members properly positioned, and prevents misalignment of the two sealing members even after assembly. This ensures the effectiveness of the sealing function provided by the two sealing members. Thus, the energy storage device according to this embodiment is an energy storage device with improved hermeticity around the shaft of the electrode terminal. The circumferential direction of the shaft is a direction along the outer periphery of the shaft and perpendicular to the axial direction of the shaft.

[0011] The first seal member and the second seal member may be arranged at positions shifted from each other in the radial direction of the shaft body when viewed from the axial direction.

[0012] According to this configuration, the two seal members are radially offset from each other, thereby reducing stress concentration around the seal members. This prevents cracking of components located near the seal members, and the two seal members are appropriately compressed by the axial compressive force applied when fixing the electrode terminal to the wall. Therefore, the first seal member can be properly adhered to both the terminal body and the insulating member, and the second seal member can be properly adhered to both the insulating member and the wall. As a result, a tight seal around the shaft body is more reliably ensured. The radial direction of the shaft body refers to the span between the opposing outer circumferential surfaces of the shaft body across the central axis of the shaft. The fact that the first and second seal members are radially offset from each other when viewed axially means that the center lines of the first and second seal members do not coincide in a plan view.

[0013] The first seal member may be disposed closer to the shaft body in the radial direction than the second seal member.

[0014] With this configuration, the axial compressive force applied when fixing the electrode terminal to the wall portion acts efficiently on the first seal member, which is closer to the shaft and sandwiched between the terminal body and the insulating member. As a result, the first seal member can more reliably prevent the movement of outside air or moisture from the periphery of the terminal body toward the shaft. This configuration is useful, for example, when the distance between the periphery of the terminal body and the shaft is short. The fact that the first seal member is closer to the shaft than the second seal member means that, in a plan view, the center line of the first seal member is closer to the central axis of the shaft than the center line of the second seal member.

[0015] The second seal member may be disposed at a position closer to the shaft body in the radial direction than the first seal member.

[0016] With this configuration, the axial compressive force applied when fixing the electrode terminal to the wall portion acts efficiently on the second seal member, which is closer to the shaft and sandwiched between the insulating member and the wall portion of the container. This allows the second seal member to more reliably prevent the movement of outside air or moisture from the periphery of the insulating member toward the shaft. This configuration is useful, for example, when the distance between the periphery of the insulating member and the shaft is short. The second seal member being closer to the shaft than the first seal member means that, in a plan view, the center line of the second seal member is closer to the central axis of the shaft than the center line of the first seal member.

[0017] The wall portion may have a thin-walled portion having a through-hole formed therein through which the shaft passes, and the second accommodating portion may be formed by the thin-walled portion.

[0018] According to this configuration, the second accommodating portion that accommodates a portion of the axial direction of the second sealing member is realized by a thin-walled portion around the periphery of the through hole, and therefore the second accommodating portion can be easily formed, for example, by press processing when forming the through hole.

[0019] 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. The embodiments described below are all 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 merely examples and are not intended to limit the present invention. Furthermore, the dimensions and the like in each drawing are not strictly illustrated.

[0020] 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) of an energy storage element are aligned, the direction in which a pair of current collectors are aligned, the direction in which a pair of tabs of an electrode assembly are aligned, or the direction in which the short side surfaces of a container face each other. The Y-axis direction is defined as the direction in which the long side surfaces of a container face each other, the short direction of the short side surfaces of a container, or the thickness direction of a container. The Z-axis direction is defined as the direction in which the terminal body, current collector, and electrode assembly of an electrode terminal are aligned, the direction in which the container body and lid of an energy storage element are aligned, the longitudinal direction of the short side surfaces of a container, the winding axis direction of the electrode assembly, or the up-down direction. 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.

[0021] In the following description, for example, the positive X-axis direction refers to the direction of the X-axis arrow, and the negative X-axis direction refers to the direction opposite to the positive X-axis direction. The same applies to the Y-axis and Z-axis directions. When simply referring to the X-axis direction, it refers to both or either of the positive X-axis direction and the negative X-axis direction. The same applies to the Y-axis and Z-axis directions. Expressions indicating relative directions or attitudes, such as parallel and orthogonal, also include cases where the directions or attitudes are not strictly those of the same kind. For example, when two directions are parallel, it does not only mean that the two directions are completely parallel, but also means that the directions are substantially parallel, that is, there is a difference of, for example, a few percent. Furthermore, in the following description, when the term "insulation" is used, it means "electrical insulation."

[0022] (Embodiment) [1. General explanation of energy storage elements] First, an energy storage device 10 according to the present embodiment will be generally described with reference to Figures 1 and 2. Figure 1 is a perspective view showing the appearance of the energy storage device 10 according to the embodiment. Figure 2 is an exploded perspective view of the energy storage device 10 according to the embodiment.

[0023] 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.

[0024] 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 also be a primary battery that can use stored electricity without the user having to charge it, instead of a secondary battery. 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 polygonal prism shape, an elongated cylinder shape, or the like other than a rectangular parallelepiped shape.

[0025] As shown in FIG. 1, the energy storage device 10 includes a container 100, a pair of electrode terminals 200 (positive and negative electrodes, the same applies hereinafter), and a pair of upper insulating members 300. Also, as shown in FIG. 2, the container 100 contains a pair of lower insulating members 400, a pair of current collectors 500, and an electrode assembly 700. An electrolyte (non-aqueous electrolyte) is sealed inside the container 100, but this is not shown. The type of electrolyte is not particularly limited as long as it does not impair the performance of the energy storage device 10, and various electrolytes can be selected. In addition to the above-mentioned components, a spacer disposed above or to the side of the electrode assembly 700, or an insulating film enveloping the electrode assembly 700, etc., may also be disposed.

[0026] The container 100 is a rectangular parallelepiped (box-shaped) case having a container body 110 with an opening formed therein and a lid 120 that closes the opening of the container body 110. With this configuration, the container 100 has a structure in which the interior can be sealed by, for example, welding the container body 110 and the lid 120 together after the electrode assembly 700 and other components are housed inside the container body 110. The materials for the container body 110 and the lid 120 are not particularly limited, but are preferably weldable metals such as stainless steel, aluminum, aluminum alloy, iron, and plated steel sheet.

[0027] The container body 110 is a rectangular cylindrical member with a bottom that constitutes the main body of the container 100, and has an opening formed in the positive direction of the Z axis. The lid body 120 is a rectangular plate-like member that is long in the X axis direction and constitutes the lid of the container 100, and is positioned to close the opening of the container body 110. The lid body 120 is provided with a gas exhaust valve 122 that exhausts gas inside the container 100 when the internal pressure of the container 100 rises excessively.

[0028] The electrode assembly 700 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 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 substrate layer that is a long strip-shaped current collector foil made of copper or a copper alloy. In this embodiment, the electrode assembly 700 is formed by winding layers of positive and negative electrode plates with the separator sandwiched between them. This forms an electrode assembly main body 710 that includes a portion where the composite layer forming portion of the positive electrode plate and the composite layer forming portion of the negative electrode plate are stacked with the separator sandwiched between them. Furthermore, a plurality of tabs (composite layer non-forming portions) of the base material layer (metal foil) of the positive electrode plate are stacked to form the positive electrode tab portion 720, and a tab (composite layer non-forming portion) of the base material layer (metal foil) of the negative electrode plate are stacked to form the negative electrode tab portion 720. The tab portions 720 of the positive electrode and negative electrode are provided so as to protrude from the electrode body main body 710, as shown in FIG.

[0029] In this embodiment, the electrode assembly 700 has an oval cross-sectional shape, but the cross-sectional shape of the electrode assembly 700 may be an ellipse or other shape. The positive electrode active material and the negative electrode active material used in the composite layer may be any known material as long as they are active materials capable of absorbing and releasing lithium ions. The separator may be, for example, a microporous sheet or nonwoven fabric made of resin.

[0030] The electrode terminal 200 is a member electrically connected to the electrode body 700 via the current collector 500. The electrode terminal 200 is joined to the current collector 500 by crimping or the like, and is attached to the lid 120. Specifically, the electrode terminal 200 has a terminal body 201 disposed outside the container 100, and a shaft body 210 extending downward (in the negative Z-axis direction) from the terminal body 201. The shaft body 210 of the electrode terminal 200 is inserted into the through-hole 301 of the upper insulating member 300, the through-hole 121 of the lid 120, the through-hole 401 of the lower insulating member 400, and the through-hole 501 of the current collector 500, and is crimped. As a result, the electrode terminal 200, together with the upper insulating member 300, the lower insulating member 400, and the current collector 500, is fixed to the lid 120. The electrode terminal 200 is formed of a conductive material such as a metal, such as aluminum, an aluminum alloy, copper, or a copper alloy.

[0031] The current collector 500 is a plate-like member that electrically connects the electrode body 700 and the electrode terminal 200. The positive electrode current collector 500 is made of a metal such as aluminum or an aluminum alloy, and is joined to the positive electrode tab portion 720 of the electrode body 700. The negative electrode current collector 500 is made of a metal such as copper or a copper alloy, and is joined to the negative electrode tab portion 720 of the electrode body 700. The current collector 500 and the tab portion 720 may be joined by laser welding, resistance welding, ultrasonic welding, or the like.

[0032] The upper insulating member 300 is a flat plate-shaped member disposed between the lid 120 of the container 100 and the electrode terminal 200. The lower insulating member 400 is a flat plate-shaped member disposed between the lid 120 and the current collector 500. In this embodiment, the upper insulating member 300 and the lower insulating member 400 serve to insulate the electrode terminal 200 from the lid 120 of the container 100 and to seal the gap between the shaft 210 of the electrode terminal 200 and the through-hole 121 of the lid 120. The upper insulating member 300 and the lower insulating member 400 are formed from an insulating material such as a resin 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), or polyethersulfone (PES), or a composite material containing these resins.

[0033] The energy storage device 10 according to this embodiment includes, in addition to the upper insulating member 300 and lower insulating member 400, two sealing members near the shaft body 210 as members for improving the sealing performance around the shaft body 210 of the electrode terminal 200. Specifically, as shown in Fig. 2, the energy storage device 10 includes a first sealing member 70 and a second sealing member 80 arranged on either side of the upper insulating member 300. In this embodiment, the pair of the first sealing member 70 and the second sealing member 80 is arranged corresponding to each of the positive and negative electrode terminals 200.

[0034] The configuration of these two seal members (first seal member 70 and second seal member 80) and their surroundings will be described below with reference to FIGS.

[0035] [2. Configuration of the first seal member, the second seal member, and their surroundings] FIG. 3 is an exploded perspective view showing an electrode terminal 200 and its peripheral configuration according to an embodiment. FIG. 4A is a first cross-sectional view showing the electrode terminal 200 and its peripheral configuration according to an embodiment. FIG. 4A is a cross-section of the electrode terminal 200 of the energy storage device 10 and its peripheral portion, taken along line IV-IV in FIG. 3. FIG. 4B is a plan view showing the positional relationship between the first seal member 70 and the second seal member 80 according to an embodiment. In FIG. 4B, the center line 71 of the first seal member 70 and the center line 81 of the second seal member 80 are each represented by a chain line. The center line 71 is a line passing through the center of the width of the first seal member 70 in the radial direction of the shaft body 210 (hereinafter simply referred to as the "radial direction"), and the center line 81 is a line passing through the center of the width of the second seal member 80 in the radial direction. FIG. 5 is a second cross-sectional view showing the electrode terminal 200 and its peripheral configuration according to an embodiment. The position of the cross-section in FIG. 5 is the same as the position of the cross-section in FIG. 4A.

[0036] As shown in FIGS. 3 to 5 , energy storage device 10 according to this embodiment includes electrode terminal 200 arranged on lid 120 of container 100. Electrode terminal 200 has terminal body 201 and shaft body 210. Specifically, terminal body 201 is the flat plate-shaped upper portion of electrode terminal 200, and shaft body 210 is the rod-shaped portion protruding downward from flat terminal body 201. In this embodiment, terminal body 201 of electrode terminal 200 is arranged on the outside of container 100, and shaft body 210 of electrode terminal 200 is arranged so as to pass through through-hole 121 of lid 120.

[0037] More specifically, the electrode terminal 200 shown in each of the figures from FIG. 3 onward is a positive electrode terminal of the energy storage element 10. The positive electrode terminal 200 integrally comprises a terminal body 201 and a shaft body 210, and is entirely formed of aluminum, an aluminum alloy, or the like. It is not essential that the electrode terminal 200 integrally comprises the terminal body 201 and the shaft body 210; the terminal body 201 and the shaft body 210 may be formed of different types of conductive materials. More specifically, the peripheral configuration of the electrode terminal 200 shown in FIGS. 3 to 5 can also be used as the peripheral configuration of a negative electrode terminal 200 in which the terminal body 201 and the shaft body 210 are formed of different metals. The terminal body 201 may also be formed of different metals. More specifically, the peripheral configuration of the electrode terminal 200 shown in FIGS. 3 to 5 can also be used as the peripheral configuration of a negative electrode terminal 200 in which the terminal body 201 and the shaft body 210 are formed of different metals.

[0038] As shown in FIGS. 4A and 5 , the cylindrical portion 320 of the upper insulating member 300 is inserted into the gap between the outer peripheral surface of the shaft 210 of the electrode terminal 200 configured in this manner and the inner peripheral surface of the through-hole 121 of the lid 120. That is, the gap is filled with a portion of the upper insulating member 300. More specifically, a force in the axial direction (hereinafter simply referred to as the “axial direction”) of the shaft 210, which is applied to the shaft 210 when the shaft 210 is crimped, acts on the shaft 210 so as to expand the outer diameter of the shaft 210. Furthermore, a crimped portion 211 (see FIG. 5 ) that expands in the radial direction (hereinafter simply referred to as the “radial direction”) of the shaft 210 is formed at the tip of the shaft 210. As a result, the axial force applied to the shaft 210 acts on the cylindrical portion 320 via the current collector 500 and the lower insulating member 400 so as to compress the cylindrical portion 320 in the axial direction. As a result, the wall portion forming cylindrical portion 320 is firmly sandwiched in the radial direction between the inner peripheral surface of through hole 121 and the outer peripheral surface of shaft body 210. This seals the gap between the inner peripheral surface of through hole 121 in lid body 120 and the outer peripheral surface of shaft body 210, and in principle, ensures airtightness at the position of through hole 121 in lid body 120.

[0039] The energy storage device 10 according to this embodiment further includes, outside the container 100, two seal members (a first seal member 70 and a second seal member 80) arranged in the axial direction with the upper insulating member 300 sandwiched therebetween. Specifically, in this embodiment, the first seal member 70 and the second seal member 80 are each annular members generally called O-rings, and are formed from rubber such as silicone rubber, ethylene propylene rubber, fluororubber, nitrile rubber, styrene butadiene rubber, butyl rubber, hydrogenated nitrile rubber, acrylic rubber, chloroprene rubber, or urethane rubber. The material of the first seal member 70 and the second seal member 80 is not limited to rubber, and may be a resin such as PP or PE, which is used for the upper insulating member 300, etc.

[0040] In this embodiment, the first seal member 70 and the second seal member 80 are arranged at positions offset from each other in the radial direction in a plan view (when viewed from the positive direction of the Z axis) as shown in FIG. 4B . This allows, for example, each of the first seal member 70 and the second seal member 80 to be appropriately compressed. Specifically, in this embodiment, the first seal member 70 and the second seal member 80 are arranged concentrically in a plan view. In the example shown in FIG. 4B , the first seal member 70 and the second seal member 80 do not have overlapping portions in a plan view. However, the first seal member 70 and the second seal member 80 may partially overlap in a plan view. In other words, the first seal member 70 and the second seal member 80 being arranged at positions offset from each other in the radial direction means that the center line 71 of the first seal member 70 and the center line 81 of the second seal member 80 do not coincide in a plan view. Therefore, when viewed in a plane, if at least a portion of one of the center lines 71 and 81 does not overlap with the other of the center lines 71 and 81, it can be said that the first sealing member 70 and the second sealing member 80 are arranged at radially offset positions from each other.

[0041] In the present embodiment, the first sealing member 70 and the second sealing member 80 are each placed in a recessed receiving portion and disposed in the energy storage device 10. Specifically, as shown in FIGS. 3 to 5, a first receiving portion 310 is provided around the through hole 301 in the upper surface of the upper insulating member 300. The first receiving portion 310 is disposed in the upper insulating member 300 as an annular groove surrounding the through hole 301. A second receiving portion 125 is provided around the through hole 121 in the upper surface of the lid 120 of the container 100. The second receiving portion 125 is disposed in the wall portion (lid 120) of the container 100 as an annular groove surrounding the through hole 121.

[0042] The depth of the first accommodating portion 310 is smaller than the axial width of the first seal member 70 before compression. Therefore, before the first seal member 70 is compressed, only a portion of the first seal member 70 in the axial direction is accommodated in the first accommodating portion 310. In other words, before the shaft body 210 of the electrode terminal 200 is crimped, a portion of the first seal member 70 protrudes upward from the upper insulating member 300. The depth of the second accommodating portion 125 is smaller than the axial width of the second seal member 80 before compression. Therefore, before the second seal member 80 is compressed, only a portion of the second seal member 80 in the axial direction is accommodated in the second accommodating portion 125. In other words, before the shaft body 210 of the electrode terminal 200 is crimped, a portion of the second seal member 80 protrudes upward from the cover 120.

[0043] Thereafter, when the shaft body 210 is crimped, the first seal member 70 is entirely or almost entirely housed in the first housing portion 310 in the axial direction, as shown in FIG. 5 . That is, the first seal member 70 is compressed by the terminal body 201 and the upper insulating member 300, and is firmly attached to both the terminal body 201 and the upper insulating member 300. At this time, the second seal member 80 is entirely or almost entirely housed in the second housing portion 125 in the axial direction, as shown in FIG. 5 . That is, the second seal member 80 is compressed by the upper insulating member 300 and the cover body 120, and is firmly attached to both the upper insulating member 300 and the cover body 120. As a result, the first seal member 70 and the second seal member 80 function as members that improve the airtightness around the shaft body 210. Specifically, the first sealing member 70 functions as a member that blocks, outside the container 100, the passages of gas and liquid that connect the outside and inside of the container 100 via the gap between the terminal body 201 and the upper insulating member 300. The second sealing member 80 functions as a member that blocks, outside the container 100, the passages of gas and liquid that connect the outside and inside of the container 100 via the gap between the upper insulating member 300 and the lid 120.

[0044] As described above, the energy storage device 10 according to this embodiment includes the container 100, the electrode terminal 200, the upper insulating member 300, the first sealing member 70, and the second sealing member 80. The electrode terminal 200 has a terminal body 201 disposed outside the container 100, and a shaft 210 connected to the terminal body 201 and disposed so as to penetrate the lid 120, which is a wall portion of the container 100. The upper insulating member 300 is disposed between the terminal body 201 and the lid 120 of the container 100. The first sealing member 70 is separate from the terminal body 201 and the upper insulating member 300, is disposed between the terminal body 201 and the upper insulating member 300, and extends in the circumferential direction of the shaft 210. The second sealing member 80 is separate from the upper insulating member 300 and the lid 120 of the container 100, is disposed between the upper insulating member 300 and the lid 120, and extends in the circumferential direction. The upper insulating member 300 has a first accommodating portion 310 that forms a space for accommodating a portion of the first sealing member 70 in the axial direction of the shaft body 210. The cover body 120 has a second accommodating portion 125 that forms a space for accommodating a portion of the second sealing member 80 in the axial direction.

[0045] As described above, in the energy storage device 10 according to this embodiment, the first sealing member 70 and the second sealing member 80 are disposed on opposite sides of the upper insulating member 300 outside the container 100. Therefore, the internal space of the container 100 is not consumed by the first sealing member 70 and the second sealing member 80. This makes it possible to improve the energy density of the energy storage device 10, for example. Since the electrolyte inside the container 100 is unlikely to reach the first sealing member 70 and the second sealing member 80 outside the container 100, problems with the chemical resistance of the first sealing member 70 and the second sealing member 80 are unlikely to occur. Furthermore, the possibility that liquid (such as water) outside the container 100 will reach the shaft body 210 is reduced.

[0046] For example, when assembling the energy storage device 10 in a position where the terminal body 201 is located above the lid body 120, the first seal member 70 can be placed in the first housing portion 310 of the upper insulating member 300, and the second seal member 80 can be placed in the second housing portion 125 of the lid body 120. Therefore, the first seal member 70 and the second seal member 80 can be efficiently assembled with each appropriately positioned, and misalignment of the first seal member 70 and the second seal member 80 is suppressed even after completion. Therefore, the effectiveness of the sealing function of the first seal member 70 and the second seal member 80 is ensured.

[0047] Furthermore, the first seal member 70 and the second seal member 80 are each fabricated as separate bodies (separate components) from the upper insulating member 300, the terminal body 201, and the lid 120. Therefore, the first seal member 70 and the second seal member 80 can be fabricated by selecting a material appropriate for ensuring a tight seal around the shaft body 210, taking into consideration flexibility, mechanical strength, chemical stability, resistance to heat, and the like. For example, the first seal member 70 and the second seal member 80 can be fabricated from materials with different hardnesses. Therefore, the reaction force when compressed in the axial direction, which is a characteristic related to the sealing function of each of the first seal member 70 and the second seal member 80, can be adjusted for each of the first seal member 70 and the second seal member 80. In this way, the energy storage device 10 according to this embodiment is an energy storage device 10 in which the tight seal around the shaft body 210 of the electrode terminal 200 is improved.

[0048] In this embodiment, as shown in Figures 4A and 4B, for example, the first sealing member 70 and the second sealing member 80 are arranged at positions shifted from each other in the radial direction of the shaft body 210 when viewed from the axial direction of the shaft body 210.

[0049] In this way, because the first seal member 70 and the second seal member 80 are arranged with a radial offset from each other, stress concentration occurring in the components surrounding the first seal member 70 and the second seal member 80 can be alleviated. This makes it possible to suppress cracking of components arranged near the first seal member 70 and the second seal member 80. The first seal member 70 and the second seal member 80 are each appropriately compressed by the axial compressive force applied when fixing the electrode terminal 200 to the cover 120. Therefore, the first seal member 70 can be appropriately brought into close contact with both the terminal body 201 and the upper insulating member 300, and the second seal member 80 can be appropriately brought into close contact with both the upper insulating member 300 and the cover 120. As a result, the sealing around the shaft body 210 is more reliably ensured.

[0050] More specifically, in this embodiment, the first seal member 70 is disposed at a position closer to the shaft body 210 than the second seal member 80 in the radial direction.

[0051] With this configuration, the axial compressive force applied when fixing the electrode terminal 200 to the lid 120 acts efficiently on the first seal member 70, which is sandwiched between the terminal body 201 and the upper insulating member 300 and is closer to the shaft 210. As a result, the first seal member 70 can more reliably prevent the movement of outside air or moisture from the periphery of the terminal body 201 toward the shaft 210. This configuration is useful, for example, when the distance between the periphery of the terminal body 201 and the shaft 210 is short. Furthermore, when the negative electrode terminal 200 is made of a clad material, the first seal member 70, which is disposed along the back surface of the terminal body 201 (the surface facing the upper insulating member 300) and close to the shaft 210, reduces the possibility of electrolyte adhering to the interface where dissimilar metals come into contact. Specifically, for example, in a negative electrode terminal 200 made of a combination of copper and aluminum, the copper-aluminum interface may be exposed on the back surface of the terminal body 201. In this case, by arranging the first seal member 70 inside the interface (at a position closer to the shaft body 210), even if the electrolyte inside the container 100 creeps up close to the interface, the electrolyte is prevented from adhering to the interface, thereby preventing corrosion from occurring at the interface.

[0052] The above has described the energy storage device 10 according to the embodiment, focusing on the first seal member 70, the second seal member 80, and the surrounding configuration. However, the surrounding configuration may be different from the configuration shown in Figures 2 to 5. Therefore, below, modified examples of the first seal member 70, the second seal member 80, and the surrounding configuration that can be employed in the energy storage device 10 will be described, focusing on the differences from the above embodiment.

[0053] [3-1. Variation 1 of the embodiment] Fig. 6 is a cross-sectional view showing an electrode terminal 200 and its surrounding structure according to the first modification of the embodiment. Fig. 6 shows a cross section of a portion of an energy storage device 10a according to this modification, and the position of the cross section corresponds to the position of the cross section of the energy storage device 10 in Fig. 5. Fig. 7 is a perspective view showing the appearance of a second accommodation section 125a according to the first modification of the embodiment.

[0054] The energy storage device 10a according to this modification includes a first seal member 70a and a second seal member 80a. The first seal member 70a is disposed between the terminal body 201 and the upper insulating member 300a, and the second seal member 80a is disposed between the upper insulating member 300a and the cover 120a. At least a portion of the first seal member 70a in the axial direction is accommodated in the first housing portion 310a of the upper insulating member 300a, and at least a portion of the second seal member 80a in the axial direction is accommodated in the second housing portion 125a of the cover 120a. Furthermore, the first seal member 70a and the second seal member 80a are disposed at positions offset from each other in the radial direction of the shaft body 210 when viewed in the axial direction of the shaft body 210. These configurations are common to the energy storage device 10 according to the embodiment.

[0055] In the energy storage device 10a according to this modification, the second seal member 80a is positioned closer to the shaft body 210 in the radial direction than the first seal member 70a, and in this respect it differs from the energy storage device 10 according to the above embodiment.

[0056] With this configuration, the axial compressive force applied when fixing the electrode terminal 200 to the lid 120a acts efficiently on the second seal member 80a, which is sandwiched between the upper insulating member 300a and the lid 120a and is closer to the shaft 210. Therefore, the second seal member 80a can more reliably prevent the movement of outside air or moisture from the periphery of the upper insulating member 300a toward the shaft 210. This configuration is useful, for example, when the distance between the periphery of the upper insulating member 300a and the shaft 210 is short.

[0057] In this modified example, the second storage section 125a that stores the second seal member 80a is formed by a thin portion around the periphery of the through hole 121a of the lid 120a, unlike the second storage section 125 (see FIG. 3) according to the embodiment. That is, in this modified example, the lid 120a has a thin portion 126a in which the through hole 121a through which the shaft 210 passes is formed, as shown in FIGS. 6 and 7. The second storage section 125a is formed by the thin portion 126a. That is, in the lid 120a according to this modified example, the through hole 121a is formed in the thin portion 126a.

[0058] According to this configuration, the second housing portion 125a, which houses at least a portion of the second seal member 80a in the axial direction, is realized by the thin-walled portion around the periphery of the through-hole 121a. Therefore, the second housing portion 125a can be easily formed, for example, by the press process used to form the through-hole 121a in the lid 120a. Furthermore, the second seal member 80a is in close contact with the outer circumferential surface of the cylindrical portion 320a inserted into the through-hole 121a. Therefore, the second seal member 80a can also function as a member that blocks the passage of gas and liquid along the outer circumferential surface of the shaft body 210.

[0059] [3-2. Modification 2 of the embodiment] Fig. 8 is a first cross-sectional view showing the configuration of an electrode terminal 200 and its surroundings according to the second modification of the embodiment, and Fig. 9 is a second cross-sectional view showing the configuration of the surroundings. Figs. 8 and 9 show a cross-section of a portion of an energy storage device 10b according to this modification, and the position of the cross-section corresponds to the position of the cross-section of the energy storage device 10 in Fig. 5. Fig. 8 shows a cross-section in a state where the electrode terminal 200 and the like are separated from the lid 120b.

[0060] An energy storage device 10b according to this modification includes a first seal member 70b and a second seal member 80b. The first seal member 70b is disposed between the terminal body 201 and the upper insulating member 300, and the second seal member 80b is disposed between the upper insulating member 300 and the cover 120b. At least a portion of the first seal member 70b in the axial direction is accommodated in the first housing portion 310 of the upper insulating member 300, and at least a portion of the second seal member 80b in the axial direction is accommodated in the second housing portion 125b of the cover 120b. These configurations are common to the energy storage device 10 according to the embodiment.

[0061] In this modified example, the first seal member 70b and the second seal member 80b are disposed at the same radial position of the shaft body 210 when viewed in the axial direction of the shaft body 210. That is, in this modified example, the central axes of the first seal member 70b and the second seal member 80b (see FIG. 4B) are substantially aligned when viewed in the axial direction, which is a point of difference from the first seal member 70 and the second seal member 80 according to the embodiment.

[0062] Thus, even when the first seal member 70b and the second seal member 80b are aligned in the axial direction of the shaft body 210, the first seal member 70b and the second seal member 80b can each perform their sealing function. Specifically, the axial compressive force applied when fixing the electrode terminal 200 to the lid body 120b acts linearly on the first seal member 70b and the second seal member 80b that are positioned to overlap in the direction of the compressive force. Therefore, for example, the axial force applied to the shaft body 210 when joining the shaft body 210 and the current collector 500 can firmly compress both the first seal member 70b and the second seal member 80b. This contributes to improving the airtightness around the shaft body 210.

[0063] In this modification, the second accommodating portion 125b that accommodates the second seal member 80b is formed by a thin portion of the periphery of the through hole 121b of the lid 120b, similar to the second accommodating portion 125a according to the first modification (see FIGS. 6 and 7). That is, in this modification, the lid 120b has a thin portion 126b in which the through hole 121b through which the shaft 210 passes is formed. The second accommodating portion 125b is formed by the thin portion 126b. That is, in the lid 120b according to this modification, the through hole 121b is formed in the thin portion 126b.

[0064] With this configuration, the second storage portion 125b can be easily formed, for example, by press working or the like when forming the through hole 121b in the lid 120b. Furthermore, the second seal member 80b adheres closely to the outer peripheral surface of the tubular portion 320 inserted into the through hole 121b. Therefore, the second seal member 80b can also function as a member that blocks the passage of gas and liquid along the outer peripheral surface of the shaft body 210.

[0065] [4. Other Modifications] Although the energy storage element according to the embodiment of the present invention and its modified examples have been described above, the present invention is not limited to the above-described embodiment and modified examples. In other words, the embodiment and modified examples disclosed herein are examples in all respects, and include all modifications within the meaning and scope of the claims.

[0066] For example, the cross-sectional shapes of the first seal member 70 and the second seal member 80 are not limited to the shape (circular) shown in FIG. 4A etc. For example, the cross-sectional shapes of the first seal member 70 and the second seal member 80 may be polygonal, such as rectangular. Furthermore, the cross-sectional shapes of the first seal member 70 and the second seal member 80 may be different from each other. The cross-sectional shapes, sizes, types of materials forming the first seal member 70 and the second seal member 80 may be determined appropriately depending on the shape and size of the upper insulating member 300 etc. that compresses the seal members, the magnitude of the compressive force acting on the seal members, etc.

[0067] The method of joining shaft 210 and current collector 500 is not limited to crimping. For example, shaft 210 and current collector 500 may be joined by providing a thread on the outer periphery of the tip of shaft 210 and threading a nut onto the tip while it passes through through-hole 501 of current collector 500. In this case, by tightening the nut onto the tip of shaft 210, first seal member 70, which is arranged between terminal body 201 and upper insulating member 300, and second seal member 80, which is arranged between upper insulating member 300 and cover 120, can be compressed.

[0068] The terminal body and shaft of the energy storage element 10 may be joined during manufacturing (assembly) of the energy storage element 10. For example, a shaft fixed to the current collector 500 may be joined to a terminal body located above the upper insulating member 300 in a state in which the shaft penetrates the lower insulating member 400, the lid 120, and the upper insulating member 300. In this case, the terminal body and the shaft are joined by a joining method such as crimping or fastening with a nut (screwing a nut onto the shaft), similar to the joining method between the shaft 210 and the current collector 500 according to the embodiment. In other words, the shaft of the electrode terminal of the energy storage element 10 may be provided integrally with another member, such as the current collector 500, at a stage prior to manufacturing of the energy storage element 10. Even in this case, the first seal member 70 and the second seal member 80 still have the effect of improving the sealing performance around the shaft of the electrode terminal.

[0069] In the embodiment, the shape of the shaft body 210 is cylindrical as shown in FIG. 2 etc., but there are no particular limitations on the shape of the shaft body 210. The shape of the shaft body 210 may be a prismatic shape such as a square prism or a hexagonal prism. The planar shapes of the first seal member 70 and the second seal member 80 also do not need to be annular. For example, if the shape of the shaft body 210 is a square prism, the planar shapes of the first seal member 70 and the second seal member 80 may be rectangular annular.

[0070] In the container 100, the wall portion in which the through hole 121 through which the shaft body 210 is disposed may be formed may be other than the lid 120. For example, in the container 100 constituted by the lid 120 and the container body 110, the through hole 121 may be formed in any of the five walls (bottom wall portion and four side wall portions) of the container body 110. In other words, there is no particular limitation on the position in which the electrode terminal 200 is disposed in the energy storage element 10.

[0071] 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 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. The energy storage element 10 may also be provided with a plurality of electrode bodies.

[0072] The electrode assembly included in the energy storage device 10 does not need to be an electrode assembly in which positive and negative electrode tab portions protrude from the electrode assembly main body, such as the electrode assembly 700 according to the embodiment (see FIG. 2). For example, the energy storage device 10 may be provided with an electrode assembly having a connection portion in which base material layers (metal foils) of electrode plates are laminated on both ends of the short side surfaces of the container 100 in the opposing direction (X-axis direction). In this case, the current collector connecting the connection portion of the electrode assembly to the electrode terminal 200 may have a portion to which the shaft body 210 of the electrode terminal 200 is joined, such as the current collector 500 according to the embodiment, and a leg portion extending downward from the portion and joined to the connection portion of the electrode assembly. In other words, regardless of the shape, size, etc. of the current collector included in the energy storage device 10, the function of the first seal member 70 and the second seal member 80 to improve the sealing around the shaft body 210 is not impaired.

[0073] Any combination of the above-described components is also included within the scope of the present invention. [Industrial Applicability]

[0074] The present invention can be applied to an electric storage element such as a lithium ion secondary battery. [Explanation of symbols]

[0075] 10, 10a, 10b Storage element 70, 70a, 70b First sealing member 71, 81 center line 80, 80a, 80b Second sealing member 100 containers 110 Container body 120, 120a, 120b lid body 121, 121a, 121b, 301, 401, 501 through hole 122 Gas exhaust valve 125, 125a, 125b Second storage section 126a, 126b Thin section 200 electrode terminal 201 Terminal body 210 Shaft 211 Crimping part 300, 300a Upper insulating member 310, 310a First storage section 320, 320a cylindrical part 400 Lower insulating member 500 current collector 700 Electrode body 710 Electrode body 720 Tab section

Claims

1. An energy storage element including a container, an electrode terminal having a terminal body disposed outside the container and a shaft body connected to the terminal body and disposed so as to penetrate a wall portion of the container; an insulating member disposed between the terminal body and the wall of the container; a first seal member disposed between the terminal body and the insulating member, extending in a circumferential direction of the shaft, and separate from the terminal body and the insulating member; a second seal member disposed between the insulating member and the wall portion of the container, extending in the circumferential direction, and separate from the insulating member and the wall portion; the insulating member has a first accommodating portion that forms a space that accommodates at least a portion of the first seal member in the axial direction of the shaft body, The wall portion has a second accommodating portion that forms a space that accommodates at least a portion of the second seal member in the axial direction. Energy storage element.

2. The first seal member and the second seal member are disposed at positions shifted from each other in the radial direction of the shaft body when viewed from the axial direction. The energy storage element according to claim 1.

3. In the radial direction, the first seal member is disposed closer to the shaft body than the second seal member. The energy storage element according to claim 2.

4. In the radial direction, the second seal member is disposed at a position closer to the shaft body than the first seal member. The energy storage element according to claim 2.

5. the wall portion has a thin-walled portion formed with a through hole through which the shaft passes, The second storage portion is formed by the thin-walled portion. The energy storage element according to any one of claims 1 to 4.

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