Power storage element

Abstract

This power storage element is provided with an electrode and a current collector. The electrode is provided with a first current collector part and a second current collector part. The first current collector part is provided with a first joining section that is joined to the current collector. The second current collector part is provided with a second joining section that is joined to the first current collector part.

Description

Electric energy storage element

[0001] The present invention relates to an electric energy storage element.

[0002] Patent Document 1 discloses a battery including a battery case, an electrode body group, a positive electrode terminal, a negative electrode terminal, a positive electrode current collector, and a negative electrode current collector. The positive electrode terminal is electrically connected to the positive electrode of the electrode body group via the positive electrode current collector. The electrode body group has a plurality of electrode bodies, and each of the plurality of electrode bodies has a positive electrode tab group. The positive electrode current collector has a plurality of second positive electrode current collectors joined to the plurality of positive electrode tab groups.

[0003] Japanese Patent Application Laid-Open No. 2022-188665

[0004] In the above conventional battery, the plurality of positive electrode tab groups included in the electrode body group have a plurality of second positive electrode current collectors corresponding one-to-one, and each of the plurality of second positive electrode current collectors is joined to the positive electrode tab group corresponding to the positive electrode current collector by ultrasonic welding or the like. That is, in the above conventional battery, the same number of second positive electrode current collectors as the number of two or more positive electrode tab groups included in the electrode body group is required. Therefore, problems such as complication of the configuration of the positive electrode current collector in the battery case may occur.

[0005] The present invention has been made by the inventors of the present application newly paying attention to the above problems, and an object thereof is to provide an electric energy storage element with a simplified configuration.

[0006] The electric energy storage element according to one aspect of the present invention includes an electrode body and a current collector. The electrode body includes a first current collector and a second current collector. The first current collector includes a first joint portion directly joined to the current collector. The second current collector includes a second joint portion joined to the first current collector at a position different from the first joint portion.

[0007] The electric energy storage element according to another aspect of the present invention includes an electrode body and a current collector. The electrode body includes a first current collector and a second current collector. The first current collector includes a first joint portion joined to the current collector and a first non-joint portion not joined to the current collector. The second current collector includes a second joint portion joined to the first non-joint portion.

[0008] According to the present invention, an electric energy storage element with a simplified configuration can be provided.

[0009] Figure 1 is a perspective view showing the external appearance of an energy storage element according to an embodiment. Figure 2 is an exploded perspective view of an energy storage element according to an embodiment. Figure 3 is a cross-sectional view showing the connection configuration between a current collector and a plurality of current collecting units according to an embodiment. Figure 4 is a cross-sectional view showing the connection configuration between a current collector and a plurality of current collecting units according to a modification 1 of the embodiment. Figure 5 is a cross-sectional view showing the connection configuration between a current collector and a plurality of current collecting units according to a modification 2 of the embodiment. Figure 6 is a schematic plan view showing the configuration of an energy storage device equipped with an energy storage element according to an embodiment.

[0010] (1) An energy storage element according to one aspect of the present invention comprises an electrode body and a current collector, wherein the electrode body comprises a first current collector and a second current collector, the first current collector comprises a first joint portion directly connected to the current collector, and the second current collector comprises a second joint portion connected to the first current collector at a position different from the first joint portion.

[0011] According to one aspect of the present invention, the second current collector is electrically connected to the current collector via the first current collector. Therefore, the current collector of the energy storage element only needs to be connected to the first current collector of the two current collectors (the first and second current collectors). In other words, the current collector of the energy storage element does not need to have multiple parts that are connected to multiple current collectors. Accordingly, the energy storage element according to one aspect of the present invention is an energy storage element with a simplified structure.

[0012] (2) In the energy storage element described in (1) above, the electrode body may include an electrode body main body, the first current collector and the second current collector are located at the end of the electrode body main body, and the second joint is located between the first joint and the electrode body main body.

[0013] According to the energy storage element described in (2) above, the portion of the first current collector that is closer to the electrode body than the first junction is joined to the second current collector at the second junction. Therefore, the second current collector can be relatively short. This contributes to simplifying the configuration of the energy storage element.

[0014] (3) In the energy storage element described in (2) above, the first current collector is arranged in the first direction of the second current collector, the first current collector and the second current collector are bent in the first direction, and at the second joint, the end of the second current collector facing the first direction is joined to the first current collector.

[0015] According to the energy storage element described in (3) above, the increase in size of the first and second current collectors in the direction of protrusion from the electrode body is suppressed. This suppresses the increase in size of the energy storage element in the direction of protrusion.

[0016] (4) In the energy storage element described in any one of (1) to (3) above, the electrode body may further include a third current collector, and the third current collector may include a third joint that is joined to the second current collector at a position different from the second joint.

[0017] According to the energy storage element described in (4) above, even if the number of current collectors on the electrode body increases to three, the number of current collectors to which the current collector is connected remains at one. In other words, the thickness of the portion of the electrode body connected to the current collector is maintained at the thickness of the first current collector, while the three current collectors (first current collector, second current collector, and third current collector) can be electrically connected to the current collector.

[0018] (5) In the energy storage element described in any one of (1) to (4) above, the electrode body may include a first electrode body including the first current collector and a second electrode body including the second current collector.

[0019] According to the energy storage element described in (5) above, the current collectors of the first electrode body and the second electrode body with the same polarity (first current collector and second current collector) can be electrically connected to a single current collector, and the current collector connected to the current collector can be maintained as only the first current collector.

[0020] (6) Another embodiment of the present invention provides an energy storage element comprising an electrode body and a current collector, wherein the electrode body comprises a first current collector and a second current collector, the first current collector comprising a first joint portion joined to the current collector and a first non-joint portion not joined to the current collector, and the second current collector comprising a second joint portion joined to the first non-joint portion.

[0021] In another aspect of the present invention, the second current collector is electrically connected to the current collector via the first current collector. Therefore, the current collector of the energy storage element only needs to be connected to the first current collector of the two current collectors (the first and second current collectors). In other words, the current collector of the energy storage element does not need to have multiple parts that are connected to multiple current collectors. Accordingly, the energy storage element according to another aspect of the present invention is an energy storage element with a simplified structure.

[0022] Hereinafter, with reference to the drawings, an energy storage element according to an embodiment (including its modifications) of the present invention will be described. The embodiments described below are all general or specific examples.

[0023] The numerical values, shapes, materials, components, arrangement and connection configurations of components, manufacturing processes, and manufacturing process sequences shown in the following embodiments are examples only and are not intended to limit the present invention. Furthermore, dimensions and other specifications in each figure are not strictly illustrated. In addition, the same reference numerals are used for identical or similar components in each figure.

[0024] In the following description and drawings, the X-axis direction is defined as the direction in which a pair of terminals (positive and negative, hereinafter the same) of the energy storage element are aligned, the direction in which a pair of current collectors are aligned, the direction in which a pair of current collecting parts of the electrode body are aligned, the direction parallel to the direction in which the current collecting part protrudes from the electrode body, or the direction in which a pair of short sides of the container face each other. The Y-axis direction is defined as the direction in which a pair of long sides of the container face each other, the direction in which the electrode plates of the electrode body are stacked, or the thickness direction of the electrode body or 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 longitudinal direction of the short side of the container, or the direction in which the electrode body connection part of the current collector extends. These X-axis, Y-axis, and Z-axis directions intersect each other (orthogonal in this embodiment). 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.

[0025] In the following explanation, 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. When simply referred to as "X-axis direction," it means either the bidirectional or unidirectional direction parallel to the X-axis. The same applies to the terminology related to the Y-axis and Z-axis.

[0026] Furthermore, expressions indicating relative directions or orientations, such as parallel and orthogonal, include cases where the directions or orientations are not strictly accurate. Two directions being orthogonal means not only that the two directions are perfectly orthogonal, but also that they are substantially orthogonal, for example, including a difference of a few percent. In the following explanation, "insulation" refers to "electrical insulation." The volume resistivity of an insulating material is 1 × 10⁻⁶. ６ Preferably Ωm or more, 1 × 10 ７ Ωm or greater is more preferable, 1 × 10 １０ A value of Ωm or greater is even more preferable.

[0027] (Embodiment) [1. General Description of the Energy Storage Element 10] First, a general description of the energy storage element 10 in this embodiment will be given using Figures 1 and 2. Figure 1 is a perspective view showing the external appearance of the energy storage element 10 according to the embodiment. Figure 2 is an exploded perspective view of the energy storage element 10 according to the embodiment.

[0028] The energy storage element 10 is a secondary battery, more specifically a non-aqueous electrolyte secondary battery such as a lithium-ion secondary battery. The energy storage element 10 can be 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, automated guided vehicles (AGVs), aircraft, 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.

[0029] The energy storage element 10 is not limited to a non-aqueous electrolyte secondary battery, but may be a secondary battery other than a non-aqueous electrolyte secondary battery, or a capacitor. The energy storage element 10 may also be a primary battery.

[0030] As shown in Figure 1, the energy storage element 10 comprises a container 100, a pair of terminals 200 (positive and negative electrodes, hereinafter the same), and a pair of external insulating members 300. As shown in Figure 2, the container 100 houses an electrode body 600, a pair of current collectors 500, and a pair of internal insulating members 400. An electrolyte (non-aqueous electrolyte) is sealed inside the container 100, but is not shown. 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. Furthermore, spacers and insulating films, etc. (not shown), may be arranged inside the container 100 to improve the insulation between the electrode body 600 and / or the current collectors 500 and the container 100, and / or to support the electrode body 600.

[0031] The container 100 is a rectangular parallelepiped (box-shaped) case. A rectangular parallelepiped, as used here, is a hexahedron whose faces are all rectangles or squares. The container 100 has a container body 110 and a lid 120 that closes the opening of the container body 110. After the electrode body 600 is placed inside the container body 110, the inside of the container 100 is sealed by welding the container body 110 and the lid 120 together. The material of the container body 110 and the lid 120 is not particularly limited, but it is preferable that they be weldable metals such as stainless steel, aluminum, aluminum alloy, iron, or plated steel sheet.

[0032] The container body 110 is a rectangular cylindrical member with a bottom and an opening at the top. The container body 110 has a pair of short sides 112 on both sides in the X-axis direction, a pair of long sides 113 on both sides in the Y-axis direction, and a bottom surface 114 in the negative Z-axis direction. The lid 120 is a rectangular plate-like member that closes the opening of the container body 110. The lid 120 or the container body 110 may be provided with a gas discharge valve for discharging gas from inside the container 100, and an injection port for injecting electrolyte into the container 100.

[0033] The electrode body 600 is an energy storage element (power generation element) that includes a positive electrode plate, a negative electrode plate, and a separator, and is capable of storing electricity. The electrode body 600 comprises an electrode body main body 601 and current collectors 605 provided at both ends of the electrode body main body 601 in the X-axis direction. Specifically, the positive electrode current collectors 605, namely the first current collector 615, the second current collector 625, and the third current collector 635, are provided at the end of the electrode body main body 601 in the positive X-axis direction. Three negative electrode current collectors 605 are provided at the end of the electrode body main body 601 in the negative X-axis direction. In Figure 2, only a part of one negative electrode current collector 605 is shown. The current collector 605 is formed by stacking tabs of the positive electrode current collector foil or tabs of the negative electrode current collector foil provided on the electrode body 600, and is also called a "tab section". In this embodiment, the connection between the positive electrode current collector 605 and the positive electrode current collector 500, and the connection between the negative electrode current collector 605 and the negative electrode current collector 500 are the same. Therefore, in the following, we will describe matters concerning the positive electrode current collector 605 (i.e., the first current collector 615, the second current collector 625, and the third current collector 635), and the description of matters concerning the negative electrode current collector 605 will be omitted as appropriate.

[0034] More specifically, the electrode body 600 comprises a first electrode body 610, a second electrode body 620, and a third electrode body 630. The first electrode body 610, the second electrode body 620, and the third electrode body 630 are aligned in the Y-axis direction. The Y-axis direction is an example of a first direction. If the Y-axis direction is the first direction, then one of the X-axis direction and the Z-axis direction may be the second direction, and the other of the X-axis direction and the Z-axis direction may be the third direction.

[0035] In this embodiment, the first electrode body 610, the second electrode body 620, and the third electrode body 630 are each wound-type electrode bodies formed by stacking a positive electrode plate and a negative electrode plate with a separator in between and then winding them. In Figure 2, the winding axis W of the first electrode body 610 is represented by a dashed line labeled W. The winding axis W is a hypothetical axis that serves as the central axis when winding the positive electrode plate, etc. In this embodiment, the winding axis W is parallel to the X-axis direction. The second electrode body 620 and the third electrode body 630 also have winding axes W. In Figure 2, the winding axes W of the second electrode body 620 and the third electrode body 630 are not shown. The first electrode body 610, the second electrode body 620, and the third electrode body 630 are formed in a flattened shape in a direction perpendicular to their respective winding axes W (in this embodiment, the Y-axis direction). In other words, the first electrode body 610, the second electrode body 620, and the third electrode body 630 are wound and flattened electrode bodies. These three electrode bodies (610, 620, and 630) are arranged in the Y-axis direction to form the electrode body 600 of the energy storage element 10. The electrode body body 601 of the electrode body 600 includes the main body portions (611, 621, and 631) of the three electrode bodies (610, 620, and 630).

[0036] Specifically, the first electrode body 610 comprises a first main body portion 611 and a first current collector portion 615 located at the end of the first main body portion 611. The first main body portion 611 is formed by laminating a positive electrode plate and a negative electrode plate with a separator in between. The first current collector portion 615 is formed by laminating tabs of the positive electrode current collector foil of the positive electrode plate in the Y-axis direction.

[0037] The second electrode body 620 comprises a second main body portion 621 and a second current collector portion 625 located at the end of the second main body portion 621. The second main body portion 621 is formed by laminating a positive electrode plate and a negative electrode plate with a separator in between. The second current collector portion 625 is formed by laminating tabs of the positive electrode current collector foil of the positive electrode plate in the Y-axis direction.

[0038] The third electrode body 630 comprises a third main body portion 631 and a third current collector portion 635 located at the end of the third main body portion 631. The third main body portion 631 is formed by laminating a positive electrode plate and a negative electrode plate with a separator in between. The third current collector portion 635 is formed by laminating tabs of the positive electrode current collector foil of the positive electrode plate in the Y-axis direction.

[0039] The positive electrode plate is an electrode plate (electrode plate) in which a positive electrode active material layer is formed on the surface of a positive electrode current collector foil, which is a long, strip-shaped metal foil. The negative electrode plate is an electrode plate (electrode plate) in which a negative electrode active material layer is formed on the surface of a negative electrode current collector foil, which is a long, strip-shaped metal foil. As the positive electrode current collector foil and the negative electrode current collector foil, any known material that is stable against oxidation-reduction reactions during charging and discharging can be used, such as nickel, iron, stainless steel, titanium, calcined carbon, conductive polymer, conductive glass, and Al-Cd alloy. As the positive electrode active material used in the positive electrode active material layer and the negative electrode active material used in the negative electrode active material layer, any known material that is capable of intercalating and releasing charge transport ions can be used.

[0040] The first electrode body 610, the second electrode body 620, and the third electrode body 630 of the electrode body 600 do not need to be wound-type electrodes. The first electrode body 610, the second electrode body 620, and the third electrode body 630 may be of any form, such as a stacked electrode body formed by stacking multiple flat electrode plates (positive electrode plate and negative electrode plate), or a bellows-type electrode body in which the electrode plates are folded in a bellows-like manner. The first electrode body 610, the second electrode body 620, and the third electrode body 630 do not all need to be of the same form. One of the first electrode body 610, the second electrode body 620, and the third electrode body 630 may be a wound-type electrode body, and the remaining two may be stacked-type electrodes.

[0041] In this embodiment, the multiple positive electrode current collectors 605 of the electrode body 600 are electrically connected to the positive electrode current collector 500. The multiple negative electrode current collectors 605 of the electrode body 600 are electrically connected to the negative electrode current collector 500. The specific configuration of the connection between the multiple current collectors 605 and the current collector 500 will be described later with reference to Figure 3.

[0042] The terminal 200 is a member that is electrically connected to the electrode body 600 via the current collector 500. Specifically, one of the pair of terminals 200 is electrically connected to the positive electrode plate of the electrode body 600, and the other of the pair of terminals 200 is electrically connected to the negative electrode plate of the electrode body 600. The terminal 200 is attached to the lid body 120 disposed above the electrode body 600. Specifically, the terminal 200 has a shaft portion 201 that penetrates the lid body 120. The shaft portion 201 of the terminal 200 is inserted into and caulked into the through hole 301 of the external insulating member 300, the through hole 123 of the lid body 120, the through hole 401 of the internal insulating member 400, and the through hole 511 of the current collector 500. Thereby, the terminal 200 is fixed to the lid body 120 together with the external insulating member 300, the internal insulating member 400, and the current collector 500. The terminal 200 is formed of aluminum, an aluminum alloy, copper, or a copper alloy, etc. The method of connecting the terminal 200 and the current collector 500 is not limited to caulking. The terminal 200 and the current collector 500 may be connected by welding or screw connection, etc.

[0043] The external insulating member 300 is a member that insulates the lid body 120 and the terminal 200. In the present embodiment, the external insulating member 300 also functions as a gasket that seals between the lid body 120 and the shaft portion 201 of the terminal 200. The internal insulating member 400 is a member that insulates the lid body 120 and the current collector 500. Each of the external insulating member 300 and the internal insulating member 400 is formed of a resin material having electrical insulation properties.

[0044] The current collector 500 is a member that electrically connects the electrode body 600 and the terminal 200. More specifically, the current collector 500 includes a terminal connection portion 510 connected to the terminal 200 and an electrode body connection portion 520 connected to the electrode body 600. The current collector 500 is formed of a conductive member such as aluminum, an aluminum alloy, copper, or a copper alloy.

[0045] In the present embodiment, the first current collecting portion 615 among the first current collecting portion 615, the second current collecting portion 625, and the third current collecting portion 635 included in the electrode body 600 is directly connected (joined) to the electrode body connection portion 520 included in the current collector 500 of the positive electrode. Hereinafter, the connection mode between the current collector 500 and the plurality of current collecting portions 605 will be further described while referring to FIG. 3.

[0046] [2. Connection mode between current collector 500 and plurality of current collecting parts 605] FIG. 3 is a cross-sectional view showing the connection mode between current collector 500 and plurality of current collecting parts 605 according to the embodiment. In FIG. 3, a cross-section of power storage element 10, which is a part of a cross-section parallel to the XY plane passing through line III-III in FIG. 1, is schematically shown. In FIG. 3, the illustration of container 100 is omitted.

[0047] As shown in FIGS. 2 and 3, electrode body 600 according to the present embodiment includes first current collecting part 615, second current collecting part 625, and third current collecting part 635 at the end in the positive X-axis direction. First current collecting part 615, second current collecting part 625, and third current collecting part 635 are arranged side by side in the Y-axis direction. First current collecting part 615 is formed by laminating a plurality of tabs 616, second current collecting part 625 is formed by laminating a plurality of tabs 626, and third current collecting part 635 is formed by laminating a plurality of tabs 636.

[0048] As shown in FIG. 3, first current collecting part 615, second current collecting part 625, and third current collecting part 635 are electrically connected to electrode body connection part 520 of current collector 500 in a state bent in the negative Y-axis direction. More specifically, first current collecting part 615 includes first joint part 650 directly joined to electrode body connection part 520 of current collector 500. That is, first current collecting part 615 is connected to current collector 500 at first joint part 650 without passing through other current collecting parts 605. Thereby, first current collecting part 615 is mechanically and electrically connected to current collector 500. Second current collecting part 625 includes second joint part 660 joined to first current collecting part 615 and does not include a part joined to current collector 500. Third current collecting part 635 includes third joint part 670 joined to second current collecting part 625 and does not include a part joined to current collector 500.

[0049] In other words, the first current collector 615 is directly joined to the current collector 500 (in other words, directly connected). In contrast, the second current collector 625 is indirectly connected to the current collector 500 via the first current collector 615. The third current collector 635 is indirectly connected to the current collector 500 via the first current collector 615 and the second current collector 625. That is, in this embodiment, the connection between the first current collector 615 and the current collector 500 is "direct," while the connection between the other current collectors 605 and the current collector 500 is "indirect." The "direct" connection between the first current collector 615 and the current collector 500 is in contrast to the "indirect" connection between the other current collectors 605 and the current collector 500. At the first joint 650, other members (for example, conductive adhesive) may be placed between the first current collector 615 and the current collector 500. In this case as well, it is explained that the first current collector 615 is directly connected to the current collector 500.

[0050] In this embodiment, the electrode body connection portion 520 is a plate-shaped portion arranged in a position where its thickness direction is oriented in the X-axis direction. The first current collector portion 615 is joined to the electrode body connection portion 520 in a state where it is superimposed on the inner surface (X-axis negative direction) of the electrode body connection portion 520. The first current collector portion 615 may also be joined to the electrode body connection portion 520 in a state where it is superimposed on the outer surface (X-axis positive direction) of the electrode body connection portion 520.

[0051] For example, ultrasonic bonding can be used as the method for joining the first current collector 615 to the electrode body connection 520, the method for joining the second current collector 625 to the first current collector 615, and the method for joining the third current collector 635 to the second current collector 625. These joining methods are not limited to ultrasonic bonding, and various methods such as crimping, laser welding, or resistance welding can be used. When joining these parts, backing plates not shown in Figures 2 and 3 may be used. At the first joint 650, the first current collector 615 may be joined to a backing plate positioned in the negative X-axis direction of the first current collector 615, and the first current collector 615 may also be joined to a current collector 500 positioned in the positive X-axis direction of the first current collector 615. The methods for joining the first current collector 615 and the electrode body connection 520, the methods for joining the second current collector 625 and the first current collector 615, and the methods for joining the third current collector 635 and the second current collector 625 may be the same, and at least one joining method may be different from at least one other joining method.

[0052] Thus, the first current collector 615 is directly joined to the current collector 500, whereas the second current collector 625 and the third current collector 635 are not directly joined to the current collector 500. Furthermore, the first joint 650, the second joint 660, and the third joint 670 are aligned in a direction intersecting the X-axis direction. More specifically, as shown in Figure 3, the first joint 650 is located at the end of the first current collector 615 (the end furthest from the electrode body 601 in the longitudinal direction of the first current collector 615), and the second joint 660 is located in the middle of the first current collector 615 (the portion between the end and the electrode body 601 in the longitudinal direction of the first current collector 615). The second joint 660 is located at the end of the second current collector 625 (the end furthest from the electrode body 601 in the longitudinal direction of the second current collector 625). The third joint 670 is located in the middle of the second current collector 625 (the portion between the end and the electrode body 601 in the longitudinal direction of the second current collector 625). That is, the second current collector 625 is electrically connected to the current collector 500 via the first current collector 615, and the third current collector 635 is electrically connected to the current collector 500 via the first current collector 615 and the second current collector 625. Therefore, the current collector 500 can electrically connect the first current collector 615, the second current collector 625 and the third current collector 635 to the terminal 200 without having a joint portion where the second current collector 625 and the third current collector 635 are connected.

[0053] Therefore, compared to a current collector having portions that are connected to the first current collector 615, the second current collector 625, and the third current collector 635, the current collector 500 according to this embodiment can be realized with a simplified configuration. This contributes to miniaturization and / or weight reduction of the current collector 500. These effects are achieved when there are two or more current collectors 605 that need to be electrically connected to the current collector 500. That is, the electrode body 600 only needs to have at least two current collectors 605 at its end in the positive X-axis direction. The electrode body 600 does not need to have the third current collector 635 among the first current collector 615, the second current collector 625, and the third current collector 635.

[0054] It is conceivable that the electrode body connection portion 520 (see Figures 2 and 3) provided on the current collector 500 could be joined to it by welding or the like, for example, a stack of the first current collector 615, the second current collector 625, and the third current collector 635 stacked in the X-axis direction (a laminate of current collectors 605). However, in this case, the thickness of the laminate of current collectors 605 in the X-axis direction would be the sum of the thicknesses of the three current collectors (first current collector 615, second current collector 625, and third current collector 635) in the X-axis direction. As a result, problems arise such as difficulty in joining the laminate of current collectors 605 to the electrode body connection portion 520 by welding or the like, and / or an increase in the size of the energy storage element 10 in the X-axis direction. In this regard, in the energy storage element 10 according to this embodiment, only the first current collector 615 is joined to the electrode body connection portion 520. Therefore, the electrode body connection portion 520 and the first current collection portion 615 can be joined together well by welding or the like.

[0055] In Figure 3, insulating members may be arranged in the negative Y-axis direction of the electrode body 600 and current collector 500 to suppress conductivity between the electrode body 600 and current collector 500 and the inner surface of the container body 110 (see Figure 2). Similarly, insulating members may be arranged in the positive Y-axis direction and the positive X-axis direction of the electrode body 600 and current collector 500 to suppress conductivity between the electrode body 600 and current collector 500 and the inner surface of the container body 110. These insulating members may be called spacers. These insulating members may be realized by folding a single insulating sheet.

[0056] The technical features of the energy storage element 10 according to the embodiment configured as described above can be explained, for example, as follows.

[0057] The energy storage element 10 according to this embodiment comprises an electrode body 600 and a current collector 500. The electrode body 600 comprises a first current collector 615 and a second current collector 625. The first current collector 615 comprises a first joint 650 that is directly joined to the current collector 500. The second current collector 625 comprises a second joint 660 that is joined to the first current collector 615 at a position different from the first joint 650.

[0058] Thus, in the energy storage element 10 according to this embodiment, the second current collector 625 is electrically connected to the current collector 500 via the first current collector 615. Therefore, the current collector 500 of the energy storage element 10 only needs to be connected to the first current collector 615 of the two current collectors 605 (the first current collector 615 and the second current collector 625). In other words, the current collector 500 of the energy storage element 10 does not need to have multiple parts that are connected to multiple current collectors 605. Accordingly, the energy storage element 10 according to this embodiment is an energy storage element with a simplified structure.

[0059] The shape and size of the current collector 500 shown in Figure 2 is an example of the shape and size of the current collector 500 that the energy storage element 10 may have. The current collector 500 that electrically connects the terminal 200 and the electrode body 600 should have a shape and size that allows direct connection to the first current collection section 615 and that can be housed in the container 100.

[0060] In this embodiment, the electrode body 600 comprises an electrode body main body 601. The first current collector 615 and the second current collector 625 are located at the ends of the electrode body main body 601. The second joint 660 is located between the first joint 650 and the electrode body main body 601 of the electrode body 600.

[0061] In this way, the portion of the first current collector 615 that is closer to the electrode body 601 than the first joint 650 is joined to the second current collector 625 at the second joint 660. Therefore, the second current collector 625 can be relatively short. This contributes to simplifying the configuration of the energy storage element 10.

[0062] In this embodiment, the first current collector 615 is positioned in the Y-axis direction (more specifically, the negative Y-axis direction) of the second current collector 625. The first current collector 615 and the second current collector 625 are bent in the negative Y-axis direction. At the second joint 660, the end of the second current collector 625 facing the negative Y-axis direction (the portion facing the negative Y-axis direction) is joined to the first current collector 615. In other words, in this embodiment, the ends of the first current collector 615 and the second current collector 625 that are furthest from the electrode body 601 are folded so that they face one side in the direction in which the first current collector 615 and the second current collector 625 are aligned. More specifically, the end of the second current collector 625 facing the negative Y-axis direction is the portion of the second current collector 625 facing the negative Y-axis direction, including the edge in the negative Y-axis direction. The second joint 660 is provided within the range included in this portion of the second current collector 625. In this embodiment, when a third joint 670 is provided, the end of the second current collector 625 facing the negative Y-axis direction is the portion of the second current collector 625 facing the negative Y-axis direction, specifically the portion between the edge in the negative Y-axis direction and the third joint 670 (see Figure 3). The second joint 660 is provided within the range included in this portion of the second current collector 625.

[0063] In this embodiment, the first current collector 615 and the second current collector 625, which protrude from the electrode body 601 in the X-axis direction, are electrically connected to the current collector 500 while bent in the Y-axis direction. This suppresses the increase in size of the first current collector 615 and the second current collector 625 in the direction of protrusion from the electrode body 601 (X-axis direction). As a result, the increase in size of the energy storage element 10 in the X-axis direction is suppressed.

[0064] In the energy storage element 10 according to this embodiment, the electrode body 600 further includes a third current collector 635. The third current collector 635 includes a third joint 670 which is joined to the second current collector 625 at a position different from that of the second joint 660.

[0065] Thus, in this embodiment, the electrode body 600 includes a third current collector 635 in addition to the first current collector 615 and the second current collector 625, and the only current collector 605 that is joined to the current collector 500 is the first current collector 615. In other words, the thickness of the portion of the electrode body 600 that is connected to the current collector 500 is maintained at the thickness of the first current collector 615, while the three current collectors (first current collector 615, second current collector 625, and third current collector 635) can be electrically connected to the current collector 500.

[0066] In the energy storage element 10 according to this embodiment, the electrode body 600 comprises a first electrode body 610 including a first current collector 615 and a second electrode body 620 including a second current collector 625.

[0067] With this configuration, the current collectors of the first electrode body 610 and the second electrode body 620, which have the same polarity (first current collector 615 and second current collector 625), can be electrically connected to a single current collector 500, and the current collector 605 that is joined to the current collector 500 can be maintained as only the first current collector 615.

[0068] In this embodiment, as shown in Figure 3, the first current collector 615 includes a first non-connected portion 619 that is not connected to the current collector 500, and the second current collector 625 includes a second non-connected portion 629 that is not connected to the first current collector 615. The third current collector 635 includes a third non-connected portion 639 that is not connected to the second current collector 625. In this configuration, the second current collector 625 and the first non-connected portion 619 are connected at the second connection portion 660, and the third current collector 635 and the second non-connected portion 629 are connected at the third connection portion 670. If the electrode body 600 includes a fourth current collector, which is another current collector 605, in the Y-axis positive direction of the third current collector 635, the fourth current collector and the third non-connected portion 639 may be connected at the fourth connection portion. That is, the technical features of the energy storage element 10 according to this embodiment may be described as follows.

[0069] The energy storage element 10 according to this embodiment comprises an electrode body 600 and a current collector 500. The electrode body 600 comprises a first current collector 615 and a second current collector 625. The first current collector 615 comprises a first connecting portion 650 joined to the current collector 500 and a first non-connecting portion 619 not joined to the current collector 500. The second current collector 625 comprises a second connecting portion 660 joined to the first non-connecting portion 619.

[0070] With this configuration, as described above, the current collector 500 of the energy storage element 10 only needs to be connected to the first current collector 615 of the two current collectors (first current collector 615 and second current collector 625). In other words, the current collector 500 of the energy storage element 10 does not need to have multiple parts connected to multiple current collectors 605. This makes it possible to obtain an energy storage element 10 with a simplified configuration.

[0071] The configuration of the energy storage element 10 according to this embodiment can be applied when the electrode body 600 has two or more current collectors 605. Therefore, when the number of current collectors 605 is N (where N is an integer of 2 or more), the technical features of the energy storage element 10 according to this embodiment may be described as follows.

[0072] The energy storage element 10 comprises an electrode body 600 and a current collector 500. The electrode body 600 has N (N is an integer of 2 or more) current collectors 605 arranged in the Y-axis direction. If the current collector 605 at the end in the negative Y-axis direction is designated as the first current collector, and the M-th current collector 605 from the end in the negative Y-axis direction (M is an integer of 2 or more and less than or equal to N) is designated as the M-th current collector, then the first current collector has a first joint connected to the current collector 500, and the M-th current collector has an M-th joint connected to the M-1 current collector. The M-th joint is formed at a different position from the M-1 joint.

[0073] With this configuration, even if the number N of current collectors 605 in the energy storage element 10 is 4 or more, the current collector 500 only needs to be connected to the first current collector out of the N current collectors. In other words, the current collector 500 in the energy storage element 10 does not need to have N parts that are connected to the N current collectors. This makes it possible to obtain an energy storage element 10 with a simplified structure.

[0074] The energy storage element 10 according to the embodiment has been described above. However, the energy storage element 10 may have a configuration different from that shown in Figures 1 to 3, and the energy storage element 10 may be used as an energy storage element provided in an energy storage device. Therefore, the following describes some modifications of the energy storage element 10, focusing on the differences from the above embodiment.

[0075] [3-1. Modification 1] Figure 4 is a cross-sectional view showing the connection between the current collector 500a and a plurality of current collectors 605 according to Modification 1 of the embodiment. In Figure 4, a schematic cross-section of a part of the energy storage element 10a according to this modification is shown. The position of the cross-section in Figure 4 is the same as the position of the cross-section in Figure 3, and the container 100 is not shown.

[0076] In the modified energy storage element 10a, the first current collector 615 includes a first joint 650 that is directly joined to the current collector 500a. The second current collector 625 includes a second joint 660 that is joined to the first current collector 615 at a different position from the first joint 650. The third current collector 635 includes a third joint 670 that is joined to the second current collector 625 at a different position from the second joint 660. These configurations are common to the energy storage element 10 according to the embodiment.

[0077] In the modified energy storage element 10a, the electrode body connection portion 520a of the current collector 500a is a plate-shaped portion whose thickness direction is oriented in the Y-axis direction, and in this respect it differs from the energy storage element 10 according to the embodiment. However, as described above, the basic configuration of the energy storage element 10a is the same as the basic configuration of the energy storage element 10 according to the embodiment. Therefore, the current collector 500a only needs to be joined to the first current collector 615 of the multiple current collector portions 605 (first current collector portion 615, second current collector portion 625, and third current collector portion 635 in this modified example). In other words, the current collector 500a does not need to have three parts that are joined to the three current collector portions. Therefore, the energy storage element 10a according to this modified example is an energy storage element with a simplified configuration.

[0078] In Figure 4, of the three current collectors 605, only the end of the first current collector 615 with the first joint 650 has its thickness direction (the stacking direction of the tabs 616) oriented in the Y-axis direction. However, the end of the second current collector 625 with the second joint 660 may also have its thickness direction (the stacking direction of the tabs 626) oriented in the Y-axis direction. In this case, the entire first current collector 615 may be positioned to extend in the X-axis direction. In other words, the orientation of each of the three current collectors 605 inside the container 100 (see Figures 1 and 2) may be appropriately changed according to the size of the container 100 and / or the position of other components inside the container 100.

[0079] [3-2. Modification 2] Figure 5 is a cross-sectional view showing the connection between the current collector 500b and a plurality of current collectors 605 according to Modification 2 of the embodiment. In Figure 5, a part of the cross-section of the energy storage element 10b according to this modification is schematically shown, specifically a part of the cross-section in the YZ plane passing through the shaft portion 201 of the terminal 200.

[0080] In the modified energy storage element 10b, the first current collector 615 includes a first joint 650 that is directly joined to the current collector 500b. The second current collector 625 includes a second joint 660 that is joined to the first current collector 615 at a different position from the first joint 650. The third current collector 635 includes a third joint 670 that is joined to the second current collector 625 at a different position from the second joint 660. These configurations are common to the energy storage element 10 according to the embodiment.

[0081] In the modified energy storage element 10b, the electrode body 600 has multiple current collectors 605 (first current collector 615, second current collector 625, and third current collector 635 in this modified example) that protrude toward the wall portion of the container 100 where the terminals 200 are located (lid 120 in this modified example), which distinguishes it from the energy storage element 10 in the embodiment. That is, the first current collector 615, second current collector 625, and third current collector 635 protrude from the electrode body 601 in the positive Z-axis direction. The entire current collector 500b, which includes a terminal connection portion 510b and an electrode body connection portion 520b, is positioned between the electrode body 601 and the lid 120. Furthermore, the first current collector 615, second current collector 625, and third current collector 635 are positioned in a bent state in the positive Y-axis direction.

[0082] Thus, the energy storage element 10b according to this modified example includes a configuration different from that of the energy storage element 10 according to the embodiment. However, as described above, the basic configuration of the energy storage element 10b is the same as the basic configuration of the energy storage element 10 according to the embodiment. Therefore, the current collector 500b only needs to be connected to the first current collection section 615 of the multiple current collection sections 605 (first current collection section 615, second current collection section 625, and third current collection section 635 in this modified example). In other words, the current collector 500b does not need to have three parts that are connected to the three current collection sections. Therefore, the energy storage element 10b according to this modified example is an energy storage element with a simplified configuration.

[0083] In Figure 5, insulating members 700 are arranged on both sides of the electrode body 600 and current collector 500b in the Y-axis direction to suppress electrical conductivity between the electrode body 600 and current collector 500b and the inner surface of the container body 110. However, the insulating members 700 may not be provided if the distance between the electrode body 600 and current collector 500b and the inner surface of the container body 110 is sufficiently long. The insulating members 700 may also be called spacers. The insulating members 700 arranged on both sides of the electrode body 600 and current collector 500b in the Y-axis direction may be realized by folding a single insulating sheet.

[0084] [3-3. Modification 3] Figure 6 is a schematic plan view showing the configuration of an energy storage device 900 equipped with an energy storage element 10 according to an embodiment. As shown in Figure 6, the energy storage element 10 may be used in an energy storage device 900. In this case, the technology of the present invention may be applied to at least one energy storage element 10 provided in the energy storage device 900.

[0085] The energy storage device 900 shown in Figure 6 comprises a plurality of energy storage units 800 arranged inside. Each energy storage unit 800 is composed of a plurality of electrically connected energy storage elements 10. The energy storage device 900 may also include busbars (not shown) that electrically connect the plurality of energy storage elements 10, and busbars (not shown) that electrically connect the plurality of energy storage units 800. The energy storage unit 800 or the energy storage device 900 may also include a condition monitoring device (not shown) that monitors the state of one or more energy storage elements 10. The energy storage device 900 may also consist of only one energy storage unit 800. In this case, the energy storage unit 800 may be referred to as the "energy storage device".

[0086] In this modified example, the energy storage device 900 is equipped with one or more energy storage elements 10 according to the above embodiment, but the energy storage device 900 may be equipped with one or more energy storage elements 10a or 10b according to the above modified example 1 or 2 in place of or in addition to the one or more energy storage elements 10.

[0087] [4. Other Modifications] Although the energy storage element according to the embodiment of the present invention and its modifications have been described above, the present invention is not limited to the embodiments and modifications. In other words, the embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is intended to include all modifications in the sense and scope equivalent to the claims.

[0088] It is not essential that the electrode body 600 comprises multiple electrode bodies that are separate from each other. A single electrode body in which multiple current collectors, including a first current collector and a second current collector, are arranged at the end of the electrode body body in the positive X-axis direction may be used as the electrode body 600 of the energy storage element 10.

[0089] The current collector portion 605 of the electrode body 600 does not necessarily have to be a tab portion formed by stacking tabs. At least one of the first current collector portion 615 and the second current collector portion 625 of the electrode body 600 may be a current collector portion that is exposed over the entire Z-axis area at the X-axis end of the electrode body 601, and may be a current collector portion formed by winding or stacking negative electrode current collector foil or positive electrode current collector foil. However, from the viewpoint of making it easier to adjust the orientation or shape when joining the current collector portion 605 to the current collector body 500 or other current collector portion 605, it is preferable that the current collector portion 605 is a tab portion formed by stacking tabs on the negative electrode current collector foil or positive electrode current collector foil. The current collector portion 605 may also be realized by a conductive member (metal plate, etc.) joined to a foil stack formed by stacking negative electrode current collector foil or positive electrode current collector foil.

[0090] The positional relationship of the first joint 650, the second joint 660, and the third joint 670 according to this embodiment is not limited to the positional relationship shown in Figure 3. When viewed from the Z-axis direction, the first joint 650 and the second joint 660 may be positioned to overlap each other. Even in this case, as long as the Z-axis positional ranges of the first joint 650 and the second joint 660 do not overlap, it is possible to realize a configuration in which the second current collector 625 includes a second joint 660 joined to the first current collector 615 at a different position from the first joint 650.

[0091] In the first current collector 615, which is directly connected to the current collector 500, the portion between the first connection 650 and the second connection 660 is the part through which current flows between the current collector 500 and the first main body 611, the second main body 621, and the third main body 631 (see Figure 3). Therefore, this portion may function as a melting section that melts when an excessive current flows. In this case, the melting section melts, thereby disconnecting the electrical connection between the electrode body 600 and the current collector 500.

[0092] In the energy storage element 10 according to the embodiment, the manner of connection between the positive electrode current collector 605 and the positive electrode current collector 500, and the manner of connection between the negative electrode current collector 605 and the negative electrode current collector 500, do not need to be the same. If the energy storage element 10 includes a positive electrode current collector 500 and a negative electrode current collector 500, at least one of the positive electrode current collector 500 and the negative electrode current collector 500 should be connected to a plurality of current collectors 605 in the manner shown in Figure 3.

[0093] The energy storage element 10 may have only one of the pair of terminals 200. For example, consider the case where the current collector 605 of the positive electrode of the electrode body 600 is electrically connected to the container 100, that is, when the container 100 is used as the positive electrode terminal. In this case, the energy storage element 10 may have only a current collector 500 that is electrically connected to the current collector 605 of the negative electrode of the electrode body 600, as the current collector 500 that connects the terminal 200 and the electrode body 600.

[0094] The supplementary information regarding the energy storage element 10 according to the above embodiment may also be applied to the energy storage elements 10a and 10b according to Modification 1 and 2, respectively. Configurations constructed by arbitrarily combining the components included in the above embodiment and its modifications are also within the scope of the present invention.

[0095] This invention can be applied to energy storage elements such as lithium-ion secondary batteries.

[0096] 10, 10a, 10b Energy storage element 500, 500a, 500b Current collector 510, 510b Terminal connection part 520, 520a, 520b Electrode body connection part 600 Electrode body 601 Electrode body main body 605 Current collector part 610 First electrode body 611 First main body part 615 First current collector part 619 First non-connected part 620 Second electrode body 621 Second main body part 625 Second current collector part 630 Third electrode body 631 Third main body part 635 Third current collector part 650 First connection part 660 Second connection part 670 Third connection part

Claims

1. An energy storage element comprising an electrode body and a current collector, wherein the electrode body comprises a first current collector and a second current collector, the first current collector comprises a first joint directly connected to the current collector, and the second current collector comprises a second joint connected to the first current collector at a position different from the first joint.

2. The energy storage element according to claim 1, wherein the electrode body comprises an electrode body main body, the first current collector and the second current collector are located at the end of the electrode body main body, and the second junction is located between the first junction and the electrode body main body.

3. The energy storage element according to claim 2, wherein the first current collector is arranged in the first direction of the second current collector, the first current collector and the second current collector are bent in the first direction, and at the second joint, the end of the second current collector facing the first direction is joined to the first current collector.

4. The electrode body further comprises a third current collector, the third current collector comprising a third joint connected to the second current collector at a position different from the second joint, according to any one of claims 1 to 3.

5. The energy storage element according to any one of claims 1 to 3, wherein the electrode body comprises a first electrode body including the first current collector and a second electrode body including the second current collector.

6. An energy storage element comprising an electrode body and a current collector, wherein the electrode body comprises a first current collector and a second current collector, the first current collector comprises a first joint portion connected to the current collector and a first non-joint portion not connected to the current collector, and the second current collector comprises a second joint portion connected to the first non-joint portion.

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