Energy storage element

Abstract

To suppress interference between the main body of an electrode body and a current collector.SOLUTION: A power storage element 10 includes an electrode body 200 in which electrode plates are laminated, a current collector 300 joined to the electrode body 200, and a container 100 including the electrode body 200 and the current collector 300, the electrode body 200 includes an electrode body main body 210 (main body portion), and an electrode body end portion 220 (end portion) protruding from the electrode body main body 210 along the X-axis direction (first direction). The current collector 300 includes a leg 320 that is joined to the electrode body end portion 220. The leg 320 includes an inclined surface 322 that approaches the central portion of the electrode body main body 210 as it separates from the electrode body main body 210, and the inclined surface 322 is joined to the electrode body end portion 220.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a storage element including an electrode body and a current collector joined to the electrode body.

Background Art

[0002] Conventionally, a storage element including an electrode body, a current collector, and a container that houses the electrode body and the current collector has been known. For example, in Patent Document 1, a wound electrode body is housed in a metal container. Also, a pair of current collectors are housed in the container, and a positive electrode terminal and a negative electrode terminal fixed to the wall portion of the container are connected to the pair of current collectors. The pair of current collectors support the electrode body in the container in a state of being joined to the positive electrode and the negative electrode of the electrode body.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, for example, when the storage element vibrates or the container is deformed, the main body portion of the electrode body and the current collector interfere with each other inside the container, and there is a risk that the main body portion of the electrode body and the current collector will be short-circuited (for example, the negative electrode plate of the electrode body and the positive current collector will be short-circuited).

[0005] An object of the present invention is to suppress interference between the main body portion of the electrode body and the current collector.

Means for Solving the Problems

[0006] An energy storage element according to one aspect of the present invention comprises an electrode body in which electrode plates are stacked, a current collector joined to the electrode body, and a container housing the electrode body and the current collector, wherein the electrode body comprises a main body and an end portion projecting from the main body in a first direction, the current collector has a leg portion joined to the end portion, the leg portion has an inclined surface that approaches the central portion of the electrode body as it moves away from the main body, and the inclined surface is joined to the end portion. [Effects of the Invention]

[0007] According to the energy storage element of the present invention, interference between the main body of the electrode and the current collector can be suppressed. [Brief explanation of the drawing]

[0008] [Figure 1] This is a perspective view showing the external appearance of the energy storage element according to the embodiment. [Figure 2] This is a perspective view showing the components arranged inside the container of the energy storage element according to the embodiment. [Figure 3] This is an exploded perspective view showing the individual components of the energy storage element according to the embodiment, after disassembly. [Figure 4] This is a perspective view showing a current collector according to an embodiment. [Figure 5] This is a bottom view showing a current collector according to an embodiment. [Figure 6] This is a cross-sectional view showing the joint state between the two legs and the electrode end according to the embodiment. [Figure 7] This is a cross-sectional view showing each leg portion of Modified Example 1. [Figure 8A] This is a cross-sectional view showing each leg portion of Modified Example 2. [Figure 8B] This is a cross-sectional view showing each leg portion of Modified Example 2. [Figure 9] This is a perspective view showing a current collector according to Modification 3. [Figure 10] This is a perspective view showing a current collector according to modified example 4. [Modes for carrying out the invention]

[0009] An energy storage element according to one aspect of the present invention comprises an electrode body in which electrode plates are stacked, a current collector joined to the electrode body, and a container housing the electrode body and the current collector, wherein the electrode body comprises a main body and an end portion projecting from the main body in a first direction, and the current collector has a leg portion joined to the end portion, the leg portion having an inclined surface that approaches the central part of the electrode body as it moves away from the main body, and the inclined surface is joined to the end portion.

[0010] According to this design, the inclined surface of the current collector's leg, which is joined to the end of the electrode body, is sloped so that it moves closer to the center of the electrode body as it moves away from the main body of the electrode body. As a result, the end face of the current collector is less likely to pierce the main body of the electrode body, thus suppressing interference with the main body and reducing the possibility of a short circuit.

[0011] Here, "the inclined surface is joined to the end" does not mean that the entire area of ​​the inclined surface is joined to the end of the electrode body. In other words, only a part of the inclined surface may be joined to the end.

[0012] The inclined surface may extend from one end to the other in the direction in which the inclined surface is inclined with respect to the first direction, at the portion of the leg that overlaps with the electrode body.

[0013] According to this, since the inclined surface extends from one end to the other in the direction in which the inclined surface is inclined with respect to the first direction at the point where it overlaps with the electrode body at the leg, a wide area of ​​the joint surface between the inclined surface of the leg and the end of the electrode body can be provided. Therefore, the stability of the joint between the leg and the end of the electrode body can be increased, and relative approaching movement between the current collector and the electrode body can be suppressed. As a result, interference between the main body of the electrode body and the current collector can be suppressed more reliably, and short circuits between the main body of the electrode body and the current collector can be further reduced. The point where it overlaps with the electrode body is defined as the point where the end of the electrode body protruding along the first direction and the leg of the current collector overlap in the direction in which the electrode plates are stacked at the end of the electrode body. Furthermore, the direction along the first direction is the direction in which the inclined surface is inclined with respect to the first direction.

[0014] The leg portion extends in a second direction intersecting the first direction, and an inclined surface may be provided over the entire portion overlapping the electrode body in the second direction.

[0015] According to this, since the inclined surface is provided over the entire portion overlapping the electrode body in the second direction of the leg portion, even if the electrode body and the current collector move relatively, interference of the leg portion with respect to the main body portion of the electrode body can be more reliably suppressed. Therefore, a short circuit between the main body portion of the electrode body and the current collector can be more reliably reduced.

[0016] The end portion of the leg portion close to the main body portion may be formed in a convex curved surface shape.

[0017] According to this, since the end portion of the leg portion close to the main body portion is formed in a convex curved surface shape, even if the leg portion hits the main body portion of the electrode body, it can be made difficult to penetrate. Therefore, even when the leg portion hits the main body portion of the electrode body, the possibility of a severe short circuit occurring can be reduced.

[0018] The current collector has two leg portions joined to the end portion with the end portion sandwiched therebetween, and inclined surfaces may be provided on each of the two leg portions.

[0019] According to this, each of the two leg portions provided in the current collector has an inclined surface approaching the central portion of the electrode body as it moves away from the main body portion, and this inclined surface is joined to the end portion. Since the end portion is joined to the inclined surface of each leg portion, the stability of the joining can be enhanced, and relative approach movement between the electrode body and the current collector can be suppressed. Also, the joining surface between the inclined surface of each leg portion and the end portion of the electrode body also has an inclination approaching the central portion of the electrode body as it moves away from the main body portion corresponding to the inclined surface. For this reason, the end surface of each of the two leg portions provided in the current collector has a structure that is difficult to penetrate into the main body portion of the electrode body, interference with the main body portion is suppressed, and the possibility of leading to a short circuit can be reduced.

[0020] The following description of an energy storage element relating to embodiments and modifications thereof of the present invention will be given with reference to the drawings. The embodiments and modifications described below are all general or specific examples. The numerical values, shapes, materials, components, arrangement and connection configurations of components, manufacturing processes, and the order of manufacturing processes shown in the following embodiments are examples only and are not intended to limit the present invention. Dimensions and other details in each figure are not strictly illustrated.

[0021] In the following description and drawings, the X-axis direction is defined as the direction in which the pair of electrode terminals (positive and negative, hereinafter the same) of the energy storage element are aligned, the direction in which the pair of current collectors are aligned, the direction in which the pair of upper gaskets are aligned, the direction in which the pair of lower gaskets are aligned, the direction in which the pair of spacers are aligned, the direction in which both ends of the electrode body are aligned, the winding axis direction of the electrode body, or the opposing direction of the short side of the container. The X-axis direction is an example of a first direction. The Y-axis direction is defined as the direction in which the long side of the container is aligned, the short side direction of the short side 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 aligned, the long side direction of the short side of the container, or the direction in which the legs of the current collector extend. The Z-axis direction is an example of a second direction. These X-axis, Y-axis, and Z-axis directions intersect each other (orthogonal in this embodiment). Note that depending on the usage, the Z-axis direction may not be vertical, but for the sake of explanation below, the Z-axis direction will be described as vertical.

[0022] In the following explanation, for example, the X-axis positive direction refers to the direction of the X-axis arrow, and the X-axis negative direction refers to the opposite direction. The same applies to the Y-axis and Z-axis directions. Expressions indicating relative directions or orientations, such as parallel and orthogonal, include cases where they are not strictly those directions or orientations. For example, two directions being orthogonal does not only mean that the two directions are perfectly orthogonal, but also that they are substantially orthogonal, that is, they may include a difference of, for example, a few percent.

[0023] (Embodiment) [General explanation of energy storage elements] First, a general description of the energy storage element 10 in this embodiment will be given using Figures 1 to 3. Figure 1 is a perspective view showing the external appearance of the energy storage element 10 according to the embodiment. Figure 2 is a perspective view showing the components arranged inside the container 100 of the energy storage element 10 according to the embodiment. Specifically, Figure 2 is a perspective view showing the configuration when the container body 110, spacer 800 and insulating sheet 600 are separated from the energy storage element 10, and shows the state after the current collector 300 is joined to the electrode body 200. Figure 3 is an exploded perspective view showing each component when the energy storage element 10 according to the embodiment is disassembled. Specifically, Figure 3 is a perspective view showing the components other than the container body 110, spacer 800 and insulating sheet 600 shown in Figure 2, and shows the state before the current collector 300 is joined to the electrode body 200.

[0024] The energy storage element 10 is a secondary battery capable of charging and discharging electricity, specifically a non-aqueous electrolyte secondary battery such as a lithium-ion secondary battery. The energy storage element 10 is used for power storage or power supply purposes. The energy storage element 10 is used, for example, as a battery for driving or starting the engine of mobile vehicles such as automobiles, motorcycles, watercraft, ships, snowmobiles, agricultural machinery, construction machinery, or railway vehicles for electric railways. Examples of automobiles include electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and fossil fuel (gasoline, diesel, liquefied natural gas, etc.) vehicles. Examples of railway vehicles for electric railways include electric trains, monorails, maglev trains, and hybrid trains equipped with both diesel engines and electric motors. The energy storage element 10 can also be used as a stationary battery for household or commercial use. 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 a capacitor. The energy storage element 10 may not be a secondary battery, but a primary battery that allows the user to use the stored electricity without needing to recharge it. The energy storage element 10 may also be a battery using a solid electrolyte. In this embodiment, the energy storage element 10 is shown in a rectangular parallelepiped shape (square), but the shape of the energy storage element 10 is not limited to a rectangular parallelepiped shape, and may be cylindrical, oval-shaped, or polygonal prism shape other than a rectangular parallelepiped. The energy storage element 10 may also be a pouch-type energy storage element.

[0025] As shown in Figure 1, the energy storage element 10 comprises a container 100, positive and negative electrode terminals 130, and upper gaskets 140 for the positive and negative electrodes. As shown in Figures 2 and 3, the container 100 houses lower gaskets 150 for the positive and negative electrodes, electrode bodies 200, current collectors 300 for the positive and negative electrodes, spacers 800 for the positive and negative electrodes, and insulating sheets 600. An electrolyte (non-aqueous electrolyte) is sealed inside the container 100, but it is not shown in the illustration. There are no particular restrictions on the type of electrolyte, as long as it does not impair the performance of the energy storage element 10, and various types can be selected.

[0026] The container 100 is a rectangular parallelepiped (square) shaped container having a container body 110 with an opening 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 two first wall portions 111 on both sides in the X-axis direction, two second wall portions 112 on both sides in the Y-axis direction, and a third wall portion 113 on the Z-axis negative side. Specifically, the first wall portions 111 are rectangular and plate-shaped short side portions that form the short side of the container 100. In other words, the first wall portions 111 are adjacent to the second wall portions 112 and the third wall portions 113, and have a smaller surface area (outer surface area) than the second wall portions 112. The second wall portions 112 are rectangular and plate-shaped long side portions that form the long side of the container 100. In other words, the second wall portion 112 is adjacent to the first wall portion 111 and the third wall portion 113, and has a larger surface area (outer surface area) than the first wall portion 111. The third wall portion 113 is a rectangular, plate-shaped bottom wall portion that forms the bottom surface of the container 100.

[0027] The lid 120 is a rectangular plate-like member that constitutes the lid portion of the container 100, and is positioned on the Z-axis positive side of the container body 110. In other words, the lid 120 is a wall portion that faces the third wall portion 113 and is adjacent to the first wall portion 111 and the second wall portion 112. In this embodiment, the lid 120 is provided with positive and negative electrode terminals 130, as well as a gas discharge valve 121 that releases pressure when the internal pressure of the container 100 rises, and an injection portion 122 for injecting electrolyte into the container 100.

[0028] With this configuration, the container 100 is sealed inside the container body 110 by placing the electrode body 200 with the spacer 800 attached inside the container body 110, and then joining the container body 110 and the lid 120 by welding or the like. The material of the container body 110 and the lid 120 is not particularly limited and can be made of weldable metals such as stainless steel, aluminum, or aluminum alloy. Resin can also be used as the material for the container body 110 and the lid 120.

[0029] The electrode body 200 is an energy storage element (power generation element) that comprises a positive electrode plate, a negative electrode plate, and a separator, and is capable of storing electricity. The positive electrode plate is an electrode plate in which a positive electrode active material layer is formed on a positive electrode base 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 negative electrode active material layer is formed on a negative electrode base layer, which is a long strip-shaped current collector foil made of copper or a copper alloy. As the current collector foil, any known material such as nickel, iron, stainless steel, titanium, calcined carbon, conductive polymer, conductive glass, or Al-Cd alloy can be used as appropriate. As the positive electrode active material and negative electrode active material used in the positive electrode active material layer and negative electrode active material layer, any known material can be used as long as it is an active material capable of intercalating and releasing lithium ions. The separator can be a microporous sheet made of resin or a nonwoven fabric. In this embodiment, the cross-sectional shape of the electrode body 200 is shown as an oval shape, but it may also be circular or elliptical.

[0030] The electrode body 200 is formed by winding a separator between a positive electrode plate and a negative electrode plate. Specifically, the electrode body 200 is formed by winding the positive electrode plate and the negative electrode plate with a separator in between, offset from each other in the direction of the winding axis W (in this embodiment, a virtual axis parallel to the X-axis direction). The positive electrode plate and the negative electrode plate have portions at their respective offset ends where the active material is not coated (no active material layer is formed) and the base material layer is exposed (non-active material layer portion).

[0031] In other words, as shown in Figure 3, the electrode body 200 has an electrode body body 210, which is a main body portion on which an active material layer is formed, and an electrode body end portion 220 (end portion) that protrudes from the electrode body body 210 along the positive or negative X-axis direction. One of these two electrode body end portions 220 is provided with a positive electrode focusing portion, in which the non-active material layer portions of the positive electrode plate are stacked and bundled. The other electrode body end portion 220 is provided with a negative electrode focusing portion, in which the non-active material layer portions of the negative electrode plate are stacked and bundled. Each electrode body end portion 220 is formed in an annular shape that is elongated in the Z-axis direction when viewed in the X-axis direction. A pair of opposing portions in the Y-axis direction on each electrode body end portion 220 are focusing portions 221 in which the stacked non-active material layer portions are gathered. Each focusing portion 221 extends along the Z-axis direction.

[0032] As shown in Figures 2 and 3, the electrode terminals 130 are terminals (positive and negative terminals) that are electrically connected to the positive and negative plates of the electrode body 200 via the current collector 300. In other words, the electrode terminals 130 are metal components that lead the electricity stored in the electrode body 200 to the external space of the energy storage element 10 and introduce electricity into the internal space of the energy storage element 10 to store electricity in the electrode body 200. The electrode terminals 130 are attached to a cover 120 positioned above the electrode body 200. Specifically, as shown in Figure 3, the electrode terminals 130 are fixed to the cover 120 together with the current collector 300 by inserting the shaft portion 131 into the through hole 140a of the upper gasket 140, the through hole 120a of the cover 120, the through hole 150a of the lower gasket 150, and the through hole 310a of the current collector 300, and crimping them. The electrode terminal 130 is formed of a conductive material such as aluminum, aluminum alloy, copper, copper alloy, or other metals.

[0033] The current collectors 300 are components (positive electrode current collector and negative electrode current collector) positioned on both sides of the electrode body 200 in the X-axis direction and connected to the electrode body end 220. The material of the current collectors 300 is not limited. For example, the current collector 300 on the positive electrode side is made of a metal material such as aluminum or an aluminum alloy, similar to the positive electrode base material layer of the electrode body 200. The current collector 300 on the negative electrode side is made of a metal material such as copper or a copper alloy, similar to the negative electrode base material layer of the electrode body 200. Details of the current collectors 300 will be described later.

[0034] As shown in Figure 2, the spacer 800 is a spacer placed between the electrode body 200 and the container 100. In this embodiment, the spacer 800 is a side spacer positioned to the side (in the positive or negative X-axis direction) of the electrode body 200 and the current collector 300, and is formed to extend in the Z-axis direction.

[0035] More specifically, the spacer 800 is positioned between the electrode body 200 and the current collector 300 and the ends of the first wall portion 111 and the second wall portion 112 of the container body 110, and is positioned to extend along the ends of the first wall portion 111 and the second wall portion 112. In other words, the spacer 800 is positioned to sandwich the electrode body end portion 220 and the current collector 300 from both ends in the Y-axis direction.

[0036] Here, the spacer 800 is made of an 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), polyether sulfone (PES), ceramics, and composite materials thereof. In other words, the spacer 800 insulates the electrode body 200 and current collector 300 from the container 100.

[0037] The upper gasket 140 is a component (positive electrode upper gasket and negative electrode upper gasket) that is placed between the lid 120 and the electrode terminals 130 of the container 100, and insulates and seals the space between the lid 120 and the electrode terminals 130. Specifically, the upper gasket 140 has a shape in which a through hole 140a is formed in the central part of a rectangular, substantially plate-like member into which the shaft portion 131 of the electrode terminal 130 is inserted. The upper gasket 140 is fixed to the lid 120 by inserting the shaft portion 131 into the through hole 140a and crimping it. The upper gasket 140 is made of resin such as PP, PE, PPS, PET, PEEK, PFA, PTFE, PBT, PES, etc.

[0038] The lower gasket 150 is positioned between the lid 120 of the container 100 and the current collector 300, and is an insulating member (positive electrode lower gasket and negative electrode lower gasket) that insulates the space between the lid 120 and the current collector 300. Specifically, the lower gasket 150 has a rectangular, roughly plate-like shape with a through hole 150a formed in the approximate center portion into which the shaft portion 131 of the electrode terminal 130 is inserted. The lower gasket 150 is fixed to the lid 120 by inserting the shaft portion 131 into the through hole 150a and crimping it. The lower gasket 150 is made of resin such as PP, PE, PPS, PET, PEEK, PFA, PTFE, PBT, PES, etc.

[0039] [Current collector] Next, the details of the current collector 300 will be described. The current collector 300 has a fixed end 310, which is an end fixed to the container 100 together with a lower gasket 150, which is an example of an insulating material, and two legs 320 extending from the fixed end 310. The two legs 320 of the positive electrode current collector 300 are joined to the positive electrode body end 220, and the two legs 320 of the negative electrode current collector 300 are joined to the negative electrode body end 220. Ultrasonic bonding is used as the bonding method. With this configuration, the electrode body 200 is held (supported) suspended from the lid 120 by the two current collectors 300, and shaking due to vibrations and shocks is suppressed. Although ultrasonic bonding is used as the bonding method here, any bonding method is acceptable, for example, laser welding or resistance welding may be used. Mechanical bonding such as clinch crimping may also be used.

[0040] The specific configuration of the current collector 300 will now be described. Here, the current collector 300 in the positive X-axis direction of a pair of current collectors 300 will be used as an example for explanation, but the current collector 300 in the negative X-axis direction is basically the same, so its explanation will be omitted. Figure 4 is a perspective view showing the current collector 300 according to the embodiment. Figure 5 is a bottom view (view in the negative Z-axis direction) showing the current collector 300 according to the embodiment. As shown in Figures 4 and 5, the fixed end 310 of the current collector 300 is formed in the shape of a flat plate parallel to the XY plane, and a through hole 310a is formed in the center thereof.

[0041] The fixed end portion 310 has a rectangular shape in plan view (viewed along the Z-axis), with a pair of corners in the positive X-axis direction beveled. This beveled portion 311 is inclined linearly with respect to the X-axis direction. Leg portions 320 extend from each of the beveled portions 311 in the negative Z-axis direction. Each leg portion 320 is formed to be long and flat in the Z-axis direction. The upper end portion 321 of each leg portion 320 is formed to be wider than the lower portion. Each leg portion 320 extends in the negative Z-axis direction while maintaining an overall inclination that depends on the inclination of the beveled portion 311. Therefore, the inner main surface of each leg portion 320 is a flat inclined surface 322 having an inclination corresponding to the inclination of the beveled portion 311.

[0042] The inclined surfaces 322 are formed along the entire length of each leg portion 320 in the direction of the X-axis. In other words, the inclined surfaces 322 of each leg portion 320 are inclined such that the distance between them (the distance in the Y-axis direction) decreases as they advance in the positive X-axis direction. The outer main surface of each leg portion 320 is planar and parallel to the inclined surfaces 322, and both ends in the X-axis direction are also planar. The inclined surfaces 322 of the two leg portions 320 face each other, and the focusing portion 221 of the electrode body end portion 220 is joined to each of these inclined surfaces 322.

[0043] Figure 6 is a cross-sectional view showing the joint state between the two legs 320 and the electrode body end 220 according to the embodiment. In Figure 6, the container 100 is not shown, and the winding axis W of the electrode body 200 is shown by a dashed line. The winding axis W is located in the center of the electrode body 210 of the electrode body 200 when viewed in the X-axis direction.

[0044] The inclined surface 322 of each leg 320 is joined to the focusing portion 221 of the electrode body end 220 in the Z-axis direction at the point where it overlaps with the focusing portion 221. Also, the inclined surface 322 of each leg 320 is joined to the focusing portion 221 in the X-axis direction at the point where it overlaps with the focusing portion 221 when viewed in the Y-axis direction. In other words, the entire portion of the inclined surface 322 of each leg 320 that overlaps with the focusing portion 221 when viewed in the Y-axis direction is joined to the electrode body end 220. In this state, the inclined surface 322 of each leg 320 is inclined to approach the winding axis W (the central part of the electrode body 210) as it moves away from the electrode body 210. For this reason, the joining surface 350 between the inclined surface 322 of each leg 320 and the focusing portion 221 also has an inclination that approaches the winding axis W as it moves away from the electrode body 210, corresponding to the inclined surface 322.

[0045] Here, if the first wall portion 111 of the container 100 in the positive X-axis direction is recessed, the current collector 300 will try to move toward the electrode body 210 as a result (see arrow Y1 in Figure 6). At this time, the current collector 300 will move along the joint surface 350. At this time, due to the inclination of the joint surface 350, each leg portion 320 will gradually move away from the winding axis W in the X-axis direction view (first direction view) (see arrow Y2 in Figure 6). As a result, each leg portion 320 moves toward the electrode body 210 in the X-axis direction view, so interference with the electrode body 210 is suppressed.

[0046] On the other hand, when vibration is applied to the energy storage element 10, the electrode body 210 tends to move toward each leg portion 320 as a result (see arrow Y3 in Figure 6). At this time, the electrode end portion 220 and the electrode body 210 continuous with it move along the joint surface 350. In other words, the electrode end portion 220 and the electrode body 210 gradually move toward the winding axis W when viewed in the X-axis direction (see arrow Y4 in Figure 6). As a result, the electrode end portion 220 and the electrode body 210 move in a way that bypasses each leg portion 320, and interference between each leg portion 320 and the electrode body 210 is suppressed.

[0047] [Explanation of effects] As described above, the energy storage element 10 according to this embodiment comprises an electrode body 200 in which electrode plates are stacked, a current collector 300 joined to the electrode body 200, and a container 100 that houses the electrode body 200 and the current collector 300. The electrode body 200 comprises an electrode body main body 210 (main body portion) and an electrode body end portion 220 (end portion) that protrudes from the electrode body main body 210 along the X-axis direction (first direction). The current collector 300 has a leg portion 320 joined to the electrode body end portion 220. The leg portion 320 has an inclined surface 322 that approaches the center of the electrode body main body 210 as it moves away from the electrode body main body 210, and the inclined surface 322 is joined to the electrode body end portion 220.

[0048] According to this, the inclined surface 322 of the leg portion 320 of the current collector 300, which is joined to the electrode body end portion 220, is inclined so that it approaches the center portion (winding axis W) of the electrode body 210 as it moves away from the electrode body 210. As a result, the end face of the leg portion 320 of the current collector 300 is less likely to pierce the electrode body 210, thus suppressing interference with the electrode body 210 and reducing the possibility of a short circuit. Furthermore, in this embodiment, the joining surface 350 between the inclined surface 322 of the leg portion 320 and the electrode body end portion 220 is inclined in a manner corresponding to the inclined surface 322, so that it approaches the center portion of the electrode body 210 as it moves away from the electrode body 210. Since the joining surface 350 has an inclination corresponding to the inclined surface 322, as described above, interference between the electrode body 210 and each leg portion 320 can be suppressed, and a short circuit between the electrode body 210 and the current collector 300 can be suppressed.

[0049] In particular, in this embodiment, each of the two legs 320 provided on the current collector 300 has an inclined surface 322 that approaches the center of the electrode body 210 as it moves away from the electrode body 210, and this inclined surface 322 is joined to the electrode body end 220. Since the electrode body end 220 is joined to the inclined surface 322 of each leg 320, the stability of the joint can be increased, and relative approaching movement between the electrode body 200 and the current collector 300 can be suppressed. Therefore, interference between the electrode body 210 and the current collector 300 can be suppressed more reliably, and short circuits between the electrode body 210 and the current collector 300 can be suppressed more effectively.

[0050] The inclined surface 322 extends from one end to the other in the direction along the X-axis (first direction) where it overlaps with the electrode body end 220 of the leg portion 320.

[0051] According to this, since the inclined surface 322 extends from one end to the other in the direction in which the inclined surface 322 is inclined with respect to the X-axis direction at the point where it overlaps with the electrode body end 220 of the leg portion 320, a wide area of ​​the joint surface 350 between the inclined surface 322 of the leg portion 320 and the electrode body end 220 can be provided. Therefore, the stability of the joint between the leg portion 320 and the electrode body end 220 can be increased, and relative approach movement between the current collector 300 and the electrode body 200 can be suppressed. As a result, interference between the electrode body 210 and the current collector 300 can be suppressed more reliably, and short circuits between the electrode body 210 and the current collector 300 can be further reduced.

[0052] The leg portion 320 extends in a second direction (Z-axis direction) that intersects the X-axis direction (first direction), and an inclined surface 322 is provided over the entire portion that overlaps with the electrode body end portion 220 in the second direction.

[0053] According to this, since the inclined surface 322 is provided over the entire portion of the leg portion 320 that overlaps with the electrode body end portion 220 in the second direction, interference of the leg portion 320 with respect to the electrode body 200 can be more reliably suppressed even if the electrode body 200 and the current collector 300 move relative to each other. Therefore, short circuits between the electrode body 210 and the current collector 300 can be more reliably reduced.

[0054] In this embodiment, since the electrode body end 220 and the inclined surface 322 are joined by welding, the laminated portion of the electrode plate at the electrode body end 220 is also integrated by welding. As a result, the electrode body end 220 becomes stronger, which suppresses deformation and damage to the electrode plate near the joining surface 350 at the electrode body end 220. Furthermore, since joining is done by welding, space efficiency can be reduced compared to mechanical joining such as crimping. In other words, by reducing the space consumed by the current collector 300 within the container 100, the electrode body 200 can be made larger, and as a result, the energy density can be increased.

[0055] Furthermore, if the entire portion of the leg portion 320 that overlaps with the electrode body end portion 220 is provided with an inclined surface 322, the leg portion 320 can be formed in a simple shape, and as a result, the space occupied by the leg portion 320 of the current collector 300 within the energy storage element 10 can be reduced. This makes it possible to increase the energy density of the energy storage element 10.

[0056] (modified version) The following describes various modifications of the above embodiments. In the following description, parts identical to those in the above embodiments may be denoted by the same reference numerals and their descriptions may be omitted.

[0057] [Example 1] In the above embodiment, an example was given in which both ends of each leg portion 320 in the X-axis direction are planar. However, the end of each leg portion 320 closest to the electrode body 210 may be convex curved. Figure 7 is a cross-sectional view showing each leg portion 320a according to Modification 1. Specifically, Figure 7 corresponds to Figure 6.

[0058] As shown in Figure 7, of the ends of each leg portion 320a in the X-axis direction, the end portion 323a closest to the electrode body 210 is formed in a convex curved shape (R-shape) that is convex toward the electrode body 210. The end portion 323a is continuous along the entire length of the leg portion 320a in the second direction (Z-axis direction), but it is sufficient that at least the portion of the end portion 323a that overlaps with the electrode body end portion 220 in an X-axis view is formed in a convex curved shape.

[0059] As described above, since the end portion 323a on the electrode body 210 side of each leg portion 320a is formed in a convex curved shape, even if the end portion 323a of the leg portion 320a comes into contact with the electrode body 210, it is less likely to pierce it. Therefore, even if the leg portion 320a comes into contact with the electrode body 210, the possibility of a severe short circuit can be reduced.

[0060] [Differentiation 2] In the above embodiment, an example was given in which an inclined surface 322 is provided over the entire X-axis direction at the portion of the leg portion 320 that overlaps with the electrode body end portion 220. However, the inclined surface may be provided only in a portion of the X-axis direction at the portion of the leg portion that overlaps with the electrode body end portion. Figure 8A is a cross-sectional view showing each leg portion 320b according to Modified Example 2. Figure 8B is a cross-sectional view showing each leg portion 320c according to Modified Example 2.

[0061] In Figure 8A, each leg portion 320b is plate-shaped, and its end in the positive X-axis direction is bent to be parallel to the X-axis direction. In other words, at each leg portion 320b, an inclined surface 322b is provided only in a portion of the X-axis direction at the point where it overlaps with the focusing portion 221 when viewed in the Y-axis direction.

[0062] In Figure 8B, before processing, each leg portion 320c, which has a rectangular cross-sectional shape, is chamfered (cut, polished, or pressed) to form an inclined surface 322c. In this case as well, the end of each leg portion 320c in the positive X-axis direction is parallel to the X-axis direction. In other words, in each leg portion 320c, the inclined surface 322c is provided only in a portion of the X-axis direction at the point where it overlaps with the focusing portion 221 when viewed in the Y-axis direction.

[0063] [Difference 3] In the above embodiment, an example was given in which an inclined surface 322 is provided over the entire second direction of each leg portion 320. However, an inclined surface is not required to be provided over the entire second direction of each leg portion. Figure 9 is a perspective view showing a current collector 300d according to Modification 3. As shown in Figure 9, the fixed end portion 310d of the current collector 300d is formed in a rectangular and flat shape parallel to the XY plane, and a through hole 310a is formed in the center thereof. At the fixed end portion 310d, a pair of edges along the X-axis direction are provided with legs 320d at the ends in the X-axis positive direction. At the leg portion 320d, the upper end portion 321d is parallel to the X-axis direction, but the portion directly below the upper end portion 321d is twisted, and the portion lower than this twisted portion is an inclined portion 325d that is inclined with respect to the X-axis direction. The inclined portion 325d of each leg portion 320d is formed in a flat shape, and the inner main surfaces facing each other are flat inclined surfaces 322d. When the electrode end 220 of the electrode body 200 is joined to the inclined surfaces 322d of the two legs 320d, the inclined surfaces 322d of each leg 320d are inclined so that they approach the winding axis W as they move away from the electrode body 210. Therefore, the joining surface between the inclined surface 322d of each leg 320d and the electrode end 220 also has an inclination that corresponds to the inclined surface 322d, and approaches the winding axis W as it moves away from the electrode body 210.

[0064] [Differentiation Example 4] Modification 4 describes a different form from Modification 3 in which an inclined surface is not provided on the entire second direction of each leg. Figure 10 is a perspective view showing the current collector 300e according to Modification 4. As shown in Figure 10, the fixed end 310e of the current collector 300e is formed in a rectangular and flat shape parallel to the XY plane, and a through hole 310a is formed in the center thereof. At the fixed end 310e, a pair of edges along the X-axis direction are provided with legs 320e at the ends in the X-axis positive direction. The upper end 321e of the leg 320e is parallel to the X-axis direction, but the part directly below the upper end 321e is twisted, and the part lower than this twisted part is an inclined portion 325e that is inclined with respect to the X-axis direction. The inclined portion 325e of each leg 320e is formed in a flat shape, and the inner main surfaces facing each other are flat inclined surfaces 322e. The inclined surface 322e extends from one end to the other in the direction along the X-axis (first direction) where it overlaps with the electrode end 220 of the electrode body 200 on the leg portion 320e. The inclined surface 322e of each leg portion 320e is inclined so as it moves away from the electrode body 210, it approaches the winding axis W, and the electrode end 220 of the electrode body 200 is joined to the inclined surfaces 322e of the two leg portions 320e. Therefore, the joining surface between the inclined surface 322e of each leg portion 320e and the electrode end 220 also has an inclination that approaches the winding axis W as it moves away from the electrode body 210, corresponding to the inclined surface 322e.

[0065] Furthermore, in each leg portion 320e, the portion directly below the inclined portion 325e is twisted, and the portion lower than this twisted portion is a parallel portion 326e parallel to the X-axis direction. In other words, in this modified example 4, an inclined surface 322e is provided only in the middle portion in the Z-axis direction of each leg portion 320e.

[0066] (others) Although embodiments and modified versions of the present invention have been described above, the present invention is not limited to these embodiments and their modifications. In other words, the embodiments and their modifications disclosed herein are illustrative and not restrictive in all respects. The scope of the present invention includes all modifications in the sense and scope of equivalence to the claims.

[0067] For example, in the above embodiment, the case was illustrated in which the entire portion of each leg 320 that overlaps with the electrode body end 220 is joined. However, if at least the portion of each leg that is joined to the electrode body end is an inclined surface, it is possible to obtain the effect of suppressing the relative approach movement between the current collector and the electrode body. In other words, if only a portion of the portion of each leg that overlaps with the electrode body end is joined to the electrode body end, an inclined surface may be provided only on that portion. Also, portions other than the joined portion may also be inclined surfaces. If the joined portion of the leg is an inclined surface, the space occupied by the current collector's legs within the energy storage element can be reduced, making it possible to increase the energy density of the energy storage element. Furthermore, if portions other than the joined portion are also inclined surfaces, the space occupied by the current collector's legs within the energy storage element can be further reduced, making it possible to further increase the energy density of the energy storage element.

[0068] In the embodiments described above, the electrode body is a so-called vertically wound type electrode body in which the winding axis W is parallel to the cover body 120. However, the shape of the electrode body is not limited to the wound type, and may be a stacked type in which flat plates are stacked, or a shape in which the plates and / or separators are folded in an accordion shape (a form in which the separator is folded in an accordion shape and a rectangular plate is sandwiched between them, a form in which the plate and separator are stacked and then folded in an accordion shape, etc.). In any case, it is sufficient that the inclined surface that is joined to the end (tab portion) of the electrode body at the leg portion of the current collector is inclined so that it approaches the center of the electrode body as it moves away from the electrode body body.

[0069] In the embodiments described above, the case in which the inclined surface 322 is planar was illustrated, but the inclined surface may also be curved, as long as it moves away from the electrode body and approaches the center of the electrode body.

[0070] In the embodiments described above, an example was given in which inclined surfaces 322 are provided on each of the two legs 320 of the current collector 300, but the inclined surface may be provided on only one leg. In this case, the inclined surface may be formed on only one of the two legs, or only one leg with an inclined surface may be provided on the current collector. Furthermore, the current collector may have three or more legs, and all of its legs may have an inclined surface.

[0071] The present invention also includes forms constructed by arbitrarily combining the components included in the embodiments and their modified examples. [Industrial applicability]

[0072] This invention can be applied to energy storage elements such as lithium-ion secondary batteries. [Explanation of Symbols]

[0073] 10 Energy storage elements 100 containers 110 Container body 111 First wall 112 Second wall section 113 Third wall 120 Lid 120a, 140a, 150a, 310a through hole 121 Gas discharge valve 122 Injection section 130 Electrode terminal 131 Shaft 140 Upper gasket 150 Lower gasket 200 Electrode body 210 Electrode body (main body of the electrode) 220 Electrode body end (end of the electrode body) 221 Focusing section 300, 300d, 300e current collectors 310, 310d, 310e fixed end 311 Chamfered section 320, 320a, 320b, 320c, 320d, 320e legs 321, 321d, 321e upper end 322, 322b, 322c, 322d, 322e Slope 323a End (end of current collector) 325d, 325e sloped section 326e Parallel section 350 Joint surface 600 Insulating Sheets 800 Spacer W winding shaft Y1, Y2, Y3, Y4 arrows

Claims

1. An electrode body in which electrode plates are stacked, A current collector joined to the electrode body, The system comprises an electrode body and a container for housing the current collector, The electrode body comprises a main body and an end portion that protrudes from the main body along a first direction. The current collector has legs that are joined to the end, The leg portion has an inclined surface that moves closer to the center of the electrode body as it moves away from the main body. The inclined surface is formed on the entire leg portion in the direction along the first direction, The entire length of the inclined surface in the direction along the first direction is joined to the end. Energy storage element.

2. The leg portion extends in a second direction intersecting the first direction, and the inclined surface is provided over the entire portion that overlaps with the electrode body in the second direction. The energy storage element according to claim 1.

3. The end of the leg portion closest to the main body portion is formed in a convex curved shape. The energy storage element according to claim 1 or 2.

4. The current collector has two legs that are joined to the end, with the end in between. Each of the two aforementioned legs is provided with the aforementioned inclined surface. The energy storage element according to any one of claims 1 to 3.

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