JP7528482B2 - Energy storage element - Google Patents

Description

The present invention relates to an energy storage element that includes an electrode body and a current collector connected to the electrode body.

Conventionally, a storage element that includes an electrode body in which an electrode plate is wound and a current collector connected to the end of the electrode body in the winding axis direction is widely known. For example, Patent Document 1 discloses a battery (storage element) in which the wound electrode plate is compressed at the end of the wound electrode body (electrode body) and a terminal member (current collector) is joined to form a terminal joint.

JP 2014-32936 A

In the conventional energy storage element described above, there is a risk of wrinkles occurring in the electrode plates of the electrode body. For example, in the energy storage element disclosed in the above Patent Document 1, all of the electrode plates at the end of the electrode body are bundled and compressed, and the current collectors are joined to form a terminal joint. However, the inventors of the present application have found that in such a configuration, wrinkles may occur at the terminal joint and its surroundings in the electrode plates due to the electrode body expanding and contracting as the energy storage element is charged and discharged. When wrinkles occur in the electrode plates, there is a problem that the thickness of the electrode plates increases and the reaction force generated in the energy storage element increases. If the reaction force increases, it may lead to breakage of the electrode plates or damage to the module frame when the energy storage element is modularized.

The present invention was made in consideration of the above problems, and aims to provide an energy storage element that can prevent wrinkles from occurring on the electrode plates of the electrode body.

In order to achieve the above object, the energy storage element according to one aspect of the present invention is an energy storage element including an electrode body having a wound electrode plate and a first current collector connected to one end of the electrode body in the winding axis direction, the electrode body having an electrode body main body portion and a first electrode plate end group and a second electrode plate end group each having a plurality of electrode plate ends that are arranged protruding from the electrode body main body portion at the one end at a position sandwiching the winding axis, the first electrode plate end group having a first end group that is a plurality of electrode plate ends that are joined to the first current collector, and a second end group that is a plurality of electrode plate ends that are not joined to the first current collector.

According to this, in the energy storage element, the electrode body has a first plate end group and a second plate end group at positions sandwiching the winding axis at one end, and the first plate end group has a first end group which is a plurality of plate end portions joined to the first current collector, and a second end group which is a plurality of plate end portions not joined to the first current collector. In this way, instead of joining the first current collector to all of the plate end portions of the first plate end group, the first current collector is joined to the first end group, and the first current collector is not joined to the second end group. This makes it possible to reduce the number of plate end portions joined to the first current collector, thereby suppressing the occurrence of wrinkles in the plate.

The second plate end group may also have a third end group, which is a plurality of plate ends joined to the first current collector, and a fourth end group, which is a plurality of plate ends not joined to the first current collector, and the third end group may be arranged closer to the winding axis than the first end group.

According to this, in the electrode body, the second plate end group has a third end group joined to the first current collector and a fourth end group not joined to the first current collector, and the third end group is arranged closer to the winding axis than the first end group. In this way, when the first current collector is joined to two places within the same circumference of the plate, wrinkles are likely to occur in the plate, so the third end group joined to the first current collector of the second plate end group is arranged closer to the winding axis than the first end group joined to the first current collector of the first plate end group. In other words, the first end group and the third end group are arranged at positions with different distances from the winding axis so that they are located on different circumferences of the plate. This makes it possible to suppress wrinkles from occurring in the plate.

The number of electrode plate ends in the third end group may be less than the number of electrode plate ends in the first end group.

According to this, in the electrode body, the number of electrode plate ends in the third end group is configured to be less than the number of electrode plate ends in the first end group. In this way, since the third end group near the winding axis of the electrode body is more susceptible to wrinkles than the first end group, the number of electrode plate ends in the third end group is made less than the number of electrode plate ends in the first end group. This makes it possible to prevent wrinkles from occurring in the third end group, which is more susceptible to wrinkles, and therefore to prevent wrinkles from occurring in the electrode plate as a whole.

The third end group may also have a smaller bonding area with the first current collector than the first end group.

According to this, in the electrode body, the third end group is configured to have a smaller bonding area with the first current collector than the first end group. In this way, since the third end group near the winding axis of the electrode body is more susceptible to wrinkling than the first end group, the bonding area with the first current collector is made smaller for the third end group than for the first end group. This makes it possible to prevent wrinkling from occurring in the third end group, which is prone to wrinkling, and therefore to prevent wrinkling from occurring in the electrode plate as a whole.

Furthermore, a second current collector is provided that is connected to the other end of the electrode body in the winding axis direction, and the electrode body has a third plate end group that is arranged at the other end, protruding from the electrode body main body at a position corresponding to the first plate end group, and the third plate end group has a fifth end group that is a plurality of plate ends that are joined to the second current collector, and a sixth end group that is a plurality of plate ends that are not joined to the second current collector, and the fifth end group is arranged at a position corresponding to the second end group, and the sixth end group is arranged at a position corresponding to the first end group.

According to this, the electrode body has a third electrode plate end group at a position corresponding to the first electrode plate end group at the other end, and the third electrode plate end group has a fifth end group joined to the second current collector at a position corresponding to the second end group, and a sixth end group not joined to the second current collector at a position corresponding to the first end group. In this way, when current collectors are joined to both ends of the electrode body, wrinkles are likely to occur in the electrode plate, so the fifth end group joined to the second current collector in the third electrode plate end group is arranged at a position corresponding to the second end group not joined to the first current collector in the first electrode plate end group. Also, the sixth end group not joined to the second current collector in the third electrode plate end group is arranged at a position corresponding to the first end group joined to the first current collector in the first electrode plate end group. In other words, when one end of the electrode body is not joined to the first current collector, the other end is joined to the second current collector, and when one end of the electrode body is joined to the first current collector, the other end is not joined to the second current collector. This makes it possible to suppress wrinkles from occurring in the electrode plate.

The present invention can be realized not only as such an energy storage element, but also as the electrode body (and current collectors (first current collector, second current collector)) that the energy storage element includes.

The energy storage element of the present invention can prevent wrinkles from forming on the electrode plates of the electrode body.

1 is a perspective view showing the appearance of an energy storage element according to an embodiment; FIG. 2 is an exploded perspective view showing each component of the energy storage element according to the embodiment. 4 is a side view showing the configuration of an end portion of the electrode body of the embodiment. FIG. 4 is a cross-sectional view showing a connection configuration between an end portion of an electrode body of an electrode body according to an embodiment and an electrode connection portion of a current collector. FIG. 10 is a cross-sectional view showing a connection configuration between an electrode body end portion and an electrode connection portion of a current collector of an electrode body according to a first modified example of an embodiment. FIG. 11 is a cross-sectional view showing a connection configuration between an end portion of an electrode body and an electrode connection portion of a current collector in an electrode body according to a second modified example of an embodiment. FIG.

The following describes an energy storage element according to an embodiment (and its modified examples) of the present invention with reference to the drawings. Note that the embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, component placement and connection forms, manufacturing processes, and the order of manufacturing processes shown in the following embodiments are merely examples and are not intended to limit the present invention. Also, the dimensions and the like are not strictly illustrated in each figure.

In the following description and drawings, the direction in which a pair of electrode terminals (positive and negative) of the storage element are arranged, the direction in which a pair of current collectors (positive and negative) are arranged, the winding axis direction of the electrode body, or the opposing direction of the short sides of the container is defined as the X-axis direction. The opposing direction of the long sides of the container, or the thickness direction of the container, is defined as the Y-axis direction. The direction in which the container body and the lid of the container are arranged, the direction in which the electrode terminals and current collectors are arranged, or the up-down direction is defined as the Z-axis direction. These X-axis, Y-axis, and Z-axis directions intersect with each other (orthogonal in this embodiment). Note that, depending on the mode of use, the Z-axis direction may not be the up-down direction, but for convenience of explanation, the following description will be given assuming that the Z-axis direction is the up-down direction.

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

(Embodiment)
[1 General Description of Energy Storage Element 10]
First, a general description of an energy storage device 10 according to the present embodiment will be given. Fig. 1 is a perspective view showing the appearance of the energy storage device 10 according to the present embodiment. Fig. 2 is an exploded perspective view showing each component of the energy storage device 10 according to the present embodiment.

The energy storage element 10 is a secondary battery that can charge and discharge electricity, specifically a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery. The energy storage element 10 is used as a battery for driving or starting the engine of a moving object such as an automobile, motorcycle, watercraft, ship, snowmobile, agricultural machinery, construction machinery, or railroad car for electric railway. Examples of the automobile include an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), and a gasoline-powered automobile. Examples of the railroad car for the electric railway include a train, a monorail, and a linear motor car. The energy storage element 10 can also be used as a stationary battery for home use or for a generator.

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, a capacitor, or a primary battery. In the present embodiment, the energy storage element 10 is illustrated as having a rectangular parallelepiped (corner) shape, but the shape of the energy storage element 10 is not limited to a rectangular parallelepiped shape, and may be a polygonal prism shape, a cylindrical shape, an oval cylindrical shape, or the like other than a rectangular parallelepiped shape. The energy storage element 10 may also be a laminate type energy storage element.

As shown in FIG. 1, the energy storage element 10 includes a container 100 and a pair of electrode terminals 200 and 300 (positive and negative), and as shown in FIG. 2, the container 100 contains an electrode body 400 and a pair of current collectors 500 and 600 (positive and negative). Between the container 100 and the electrode terminals 200 and 300, and between the container 100 and the current collectors 500 and 600, gaskets and the like are arranged to improve electrical insulation and airtightness, and an electrolyte (non-aqueous electrolyte) is sealed inside the container 100, but is not shown. There is no particular limit to 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. In addition to the above components, a spacer arranged on the side or below the electrode body 400, an insulating film that wraps the electrode body 400, etc. may be arranged.

The container 100 is a rectangular parallelepiped (square or box-shaped) case having a container body 110 with an opening formed therein and a lid body 120 that closes the opening of the container body 110. With this configuration, the container 100 has a structure in which the inside can be sealed by housing the electrode body 400 and the like inside the container body 110 and then joining the container body 110 and the lid body 120 by welding or the like. The material of the container 100 (container body 110 and lid body 120) is not particularly limited, but is preferably a weldable metal such as stainless steel, aluminum, aluminum alloy, iron, or plated steel sheet.

The container body 110 is a rectangular cylindrical member with a bottom that constitutes the main body of the container 100, and has an opening on the positive Z-axis side. That is, the container body 110 has a pair of rectangular and planar long sides on both sides in the Y-axis direction, a pair of rectangular and planar short sides on both sides in the X-axis direction, and a rectangular and planar bottom on the negative Z-axis side. The lid 120 is a rectangular plate-like member that constitutes the lid of the container 100, and is arranged to extend in the X-axis direction in the positive Z-axis direction of the container body 110. The lid 120 is provided with a gas exhaust valve 121 that exhausts gas from inside the container 100 when the internal pressure of the container 100 increases. The container 100 may be provided with a liquid injection section for injecting an electrolyte into the container 100.

The electrode terminals 200 and 300 are rectangular, flat terminal members (positive and negative terminals) electrically connected to the electrode body 400 via the current collectors 500 and 600. That is, the electrode terminals 200 and 300 are metal members for leading out electricity stored in the electrode body 400 to the external space of the energy storage element 10 and for introducing electricity into the internal space of the energy storage element 10 to store electricity in the electrode body 400. The electrode terminals 200 and 300 are formed of conductive materials such as metals such as aluminum, aluminum alloy, copper, or copper alloy. The electrode terminals 200 and 300 are connected (joined) to the current collectors 500 and 600 by crimping or the like and are attached to the cover body 120. In this embodiment, the electrode terminal 200 is a positive terminal and the electrode terminal 300 is a negative terminal, but the electrode terminal 300 may be a positive terminal and the electrode terminal 200 may be a negative terminal.

The electrode body 400 is a storage element (power generation element) that includes a positive electrode plate, a negative electrode plate, and a separator and can store electricity. The positive electrode plate is an electrode plate in which a positive electrode active material layer is formed on a positive electrode substrate layer that is a long strip-shaped current collecting 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 substrate layer that is a long strip-shaped current collecting foil made of copper or a copper alloy. As the current collecting foil used for the positive electrode plate and the negative electrode plate, nickel, iron, stainless steel, titanium, baked carbon, conductive polymer, conductive glass, Al-Cd alloy, or other known material may be used as appropriate. The separator is, for example, a long strip-shaped microporous sheet made of resin.

The positive electrode active material used in the positive electrode active material layer of the positive electrode plate and the negative electrode active material used in the negative electrode active material layer of the negative electrode plate can be any known material that can absorb and release lithium ions. Examples of the positive electrode active material include polyanion compounds such as LiMPO ₄ , LiMSiO ₄ , and LiMBO ₃ (M is one or more transition metal elements selected from Fe, Ni, Mn, Co, etc.), lithium titanate, spinel-type lithium manganese oxides such as LiMn ₂ O ₄ and LiMn _1.5 Ni _0.5 O ₄ , and lithium transition metal oxides such as LiMO ₂ (M is one or more transition metal elements selected from Fe, Ni, Mn, Co, etc.). Examples of the negative electrode active material include lithium metal, lithium alloys (lithium-silicon, lithium-aluminum, lithium-lead, lithium-tin, lithium-aluminum-tin, lithium-gallium, and lithium metal-containing alloys such as Wood's alloy), as well as alloys capable of absorbing and releasing lithium, carbon materials (e.g., graphite, difficult-to-graphitize carbon, easy-to-graphitize carbon, low-temperature fired carbon, amorphous carbon, etc.), silicon oxides, metal oxides, lithium metal oxides (Li ₄ Ti ₅ O ₁₂ , etc.), polyphosphate compounds, and compounds of transition metals and elements of Groups 14 to 16, such as Co ₃ O ₄ and Fe ₂ P, which are generally called conversion negative electrodes.

The electrode body 400 is formed by stacking a positive electrode plate, a negative electrode plate, and a separator. Specifically, the electrode body 400 is formed by winding a separator disposed between the positive electrode plate and the negative electrode plate. More specifically, the electrode body 400 is wound with the positive electrode plate and the negative electrode plate shifted from each other in the winding axis direction through the separator. The winding axis is a virtual axis that serves as the central axis when winding the positive electrode plate and the negative electrode plate, and in this embodiment, it is a straight line that passes through the center of the electrode body 400 and is parallel to the X-axis direction. The winding axis direction is the direction in which the winding axis extends, and in this embodiment, it is the X-axis direction. The positive electrode plate and the negative electrode plate have a portion (active material layer non-formed portion) where the active material is not formed (coated) and the base material layer is exposed at the end in the shifted direction.

2, the electrode body 400 has, at one end, a positive electrode side electrode body end 410 on which the active material layer non-forming portion of the positive electrode plate is laminated, and at the other end, a negative electrode side electrode body end 420 on which the active material layer non-forming portion of the negative electrode plate is laminated. In other words, the electrode body 400 has an electrode body main body 430 and a pair of electrode body ends 410 and 420 (positive electrode side and negative electrode side) that protrude from the electrode body main body 430 on both sides in the X-axis direction. A more detailed description of the configuration of the electrode body ends 410 and 420 will be given later.

The electrode body main body 430 is a part that constitutes the main body of the electrode body 400, and specifically, is a part of the electrode body 400 other than the electrode body ends 410 and 420. In other words, the electrode body main body 430 is an oval-shaped part (active material layer forming part) formed by winding the part where the active material layer of the positive electrode plate and the negative electrode plate is formed (coated) and the separator. As a result, the electrode body main body 430 has a pair of electrode body flat parts 431 aligned in the Y-axis direction in the central part, and has a pair of electrode body curved parts 432 on both sides of the pair of electrode body flat parts 431 in the Z-axis direction. The electrode body flat parts 431 are rectangular flat parts (flat parts of a rectangular parallelepiped shape) that are arranged at a position sandwiching the above-mentioned winding axis in the Y-axis direction and extend parallel to the XZ plane, and connect the ends of the pair of electrode body curved parts 432. The electrode curved portion 432 is a curved portion (semi-cylindrical curved portion) that is positioned on either side of the winding axis in the Z-axis direction, curves in a semicircular shape so as to protrude in the Z-axis direction when viewed from the X-axis direction, and extends in the X-axis direction.

The current collectors 500 and 600 are disposed on both sides of the electrode body 400 in the X-axis direction, and are current collector members (positive and negative current collectors) that have conductivity and rigidity and electrically connect the electrode terminals 200 and 300 to the electrode body 400. The current collectors 500 and 600 are connected (joined) to the pair of electrode terminals 200 and 300 and the pair of electrode body ends 410 and 420 of the electrode body 400. That is, the current collector 500 is connected to one end of the electrode body 400 in the winding axis direction (the electrode body end 410, which is the end in the positive direction of the X-axis), and the current collector 600 is connected to the other end of the electrode body 400 in the winding axis direction (the electrode body end 420, which is the end in the negative direction of the X-axis).

Specifically, the current collectors 500 and 600 are plate-shaped members arranged in a bent state along the container body 110 and the lid body 120 from the container body 110 to the lid body 120. The current collectors 500 and 600 are fixedly connected (joined) to the lid body 120. With this configuration, the electrode body 400 is held (supported) in a state suspended from the lid body 120 by the current collectors 500 and 600, and shaking due to vibration, impact, etc. is suppressed. The material of the current collectors 500 and 600 is not particularly limited, but for example, the positive electrode side current collector 500 is formed of aluminum or an aluminum alloy, etc., like the positive electrode base layer of the electrode body 400, and the negative electrode side current collector 600 is formed of copper or a copper alloy, etc., like the negative electrode base layer of the electrode body 400.

More specifically, the current collector 500 has a terminal connection portion 510, two electrode connection portions 520 (521, 522) aligned in the Y-axis direction, and an intermediate portion 530 disposed between the terminal connection portion 510 and the two electrode connection portions 520. The intermediate portion 530 is a rectangular, flat portion extending from the end of the terminal connection portion 510 in the positive X-axis direction toward the negative Z-axis direction, and the two electrode connection portions 520 are connected to both ends of the portion in the negative Z-axis direction in the Y-axis direction. In this way, the intermediate portion 530 connects the terminal connection portion 510 and the two electrode connection portions 520.

The terminal connection portion 510 is a flat portion disposed on the electrode terminal 200 side (upper side, Z-axis positive direction side) of the current collector 500, and is electrically and mechanically connected (joined) to the electrode terminal 200. Specifically, as shown in FIG. 2, the electrode terminal 200 has a cylindrical terminal shaft portion 210 (rivet portion) extending in the Z-axis negative direction. The terminal shaft portion 210 is inserted into the through hole 122 of the lid 120 and the through hole 511 of the terminal connection portion 510 of the current collector 500, and is crimped. As a result, the electrode terminal 200 is fixed to the lid 120 together with the current collector 500. Note that the method of connecting (joining) the electrode terminal 200 and the terminal connection portion 510 is not limited to crimping, and welding such as ultrasonic welding, laser welding, or resistance welding, or mechanical joining other than crimping such as screw fastening, etc. may be used.

The electrode connection portion 520 is a portion disposed on the electrode body 400 side (lower side, Z-axis negative direction side) of the current collector 500, and is electrically and mechanically connected (joined) to the electrode body 400. Specifically, the electrode connection portion 520 is an elongated portion extending in the Z-axis direction, and the two electrode connection portions 520 are welded to two flat portions of the electrode body end portion 410 of the electrode body 400 that are aligned in the Y-axis direction. Hereinafter, of the two electrode connection portions 520, the electrode connection portion 520 on the Y-axis negative direction side is also referred to as the electrode connection portion 521, and the electrode connection portion 520 on the Y-axis positive direction side is also referred to as the electrode connection portion 522. Note that the method of connecting (joining) the electrode body end portion 410 and the electrode connection portion 520 may be any welding method such as ultrasonic welding, laser welding, or resistance welding, or may be mechanical joining such as crimping or screw fastening. A more detailed explanation of the configuration for connecting (joining) the electrode body end portion 410 and the electrode connection portion 520 will be provided later.

Like the current collector 500, the current collector 600 has a terminal connection portion 610, two electrode connection portions 620 (621, 622) arranged in the Y-axis direction, and an intermediate portion 630 arranged between the terminal connection portion 610 and the two electrode connection portions 620. The current collector 600 has a similar configuration to the current collector 500 rotated 180° around the Z-axis direction, so detailed description is omitted. Here, the current collector 500 is an example of a first current collector, and the current collector 600 is an example of a second current collector. In this embodiment, the current collector 500 is a positive electrode current collector, and the current collector 600 is a negative electrode current collector, but the current collector 600 may be a positive electrode current collector and the current collector 500 may be a negative electrode current collector. That is, in this embodiment, the first current collector is a positive electrode current collector and the second current collector is a negative electrode current collector, but the second current collector may be a positive electrode current collector and the first current collector may be a negative electrode current collector.

[2. Description of the configuration of the electrode body ends 410 and 420 of the electrode body 400]
Next, the configuration of the electrode body ends 410 and 420 of the electrode body 400, and the connection configuration between the electrode body ends 410 and 420 and the electrode connection parts 520 (521, 522) and 620 (621, 622) of the current collectors 500 and 600 will be described in more detail. FIG. 3 is a side view showing the configuration of the electrode body ends 410 and 420 of the electrode body 400 according to this embodiment. Specifically, FIG. 3(a) is a side view showing the configuration of the electrode body end 410 when the electrode body 400 is viewed from the positive direction of the X-axis, and FIG. 3(b) is a side view showing the configuration of the electrode body end 420 when the electrode body 400 is viewed from the negative direction of the X-axis. Fig. 4 is a cross-sectional view showing a connection configuration between the electrode body ends 410 and 420 of the electrode body 400 and the electrode connectors 520 (521, 522) and 620 (621, 622) of the current collectors 500 and 600 according to the present embodiment. Specifically, Fig. 4 is a cross-sectional view showing a configuration in which the central position of the electrode body flat portion 431 of the electrode body main body 430 is cut along a plane parallel to the XY plane in a state in which the electrode connectors 520 and 620 are connected to the electrode body ends 410 and 420.

As shown in FIG. 3A, the electrode body end 410 has a first electrode plate end group 411 and a second electrode plate end group 412. The first electrode plate end group 411 and the second electrode plate end group 412 are arranged to protrude from the electrode body main body 430 at positions sandwiching the winding axis A, and are portions each having a plurality of electrode plate ends 413 of the electrode plate. In this embodiment, the electrode plate end 413 is an end (active material layer non-forming portion) of the positive electrode plate in the X-axis positive direction that protrudes in the X-axis positive direction from the Z-axis central portion of the electrode body flat portion 431 of the electrode body main body 430. In other words, the first electrode plate end group 411 has a plurality of electrode plate ends 413 arranged to protrude in the X-axis positive direction from the Z-axis central portion of the electrode body flat portion 431 on the Y-axis negative side of the pair of electrode body flat portions 431. The second electrode plate end group 412 has a plurality of electrode plate ends 413 arranged to protrude in the positive direction of the X axis from the center in the Z axis direction of the electrode body flat portion 431 on the positive side of the Y axis. In other words, the first electrode plate end group 411 and the second electrode plate end group 412 are formed by equally dividing the plurality of electrode plate ends 413 of the electrode body end portion 410.

The first electrode plate end group 411 has a first end group 411a and a second end group 411b. The first end group 411a is the part on the negative Y-axis side when the multiple electrode plate ends 413 of the first electrode plate end group 411 are divided in half, and the second end group 411b is the part on the positive Y-axis side when the multiple electrode plate ends 413 of the first electrode plate end group 411 are divided in half. The second electrode plate end group 412 has a third end group 412a and a fourth end group 412b. The third end group 412a is the part on the negative Y-axis side when the multiple electrode plate ends 413 of the second electrode plate end group 412 are divided in half, and the fourth end group 412b is the part on the positive Y-axis side.

In this way, the first end group 411a and the fourth end group 412b are arranged on the outside of the electrode body end 410, and the second end group 411b and the third end group 412a are arranged on the inside of the electrode body end 410. Since the electrode body end 410 has a wound electrode plate, the first end group 411a and the fourth end group 412b have the same outer plate end 413, and the second end group 411b and the third end group 412a have the same inner plate end 413. In other words, the first end group 411a and the fourth end group 412b do not have the same plate end 413 as the second end group 411b and the third end group 412a. Or, it can be said that the first end group 411a and the fourth end group 412b and the second end group 411b and the third end group 412a have different distances from the winding axis A. Specifically, the second end group 411b and the third end group 412a are positioned closer to the winding axis A than the first end group 411a and the fourth end group 412b.

3B, the electrode body end 420 has a third electrode plate end group 421 and a fourth electrode plate end group 422. The third electrode plate end group 421 and the fourth electrode plate end group 422 are arranged to protrude from the electrode body main body 430 at positions sandwiching the winding axis A, and are portions each having a plurality of electrode plate ends 423 of the electrode plate. In this embodiment, the electrode plate end 423 is an end (active material layer non-forming portion) in the negative X-axis direction of the negative electrode plate that protrudes in the negative X-axis direction from the Z-axis center of the electrode body flat portion 431 of the electrode body main body 430. In other words, the third electrode plate end group 421 has a plurality of electrode plate ends 423 arranged to protrude in the negative X-axis direction from the Z-axis center of the electrode body flat portion 431 on the Y-axis negative side of the pair of electrode body flat portions 431. The fourth electrode plate end group 422 has multiple electrode plate ends 423 arranged to protrude in the negative X-axis direction from the center in the Z-axis direction of the electrode body flat portion 431 on the positive Y-axis side.

The third electrode plate end group 421 has a fifth end group 421a and a sixth end group 421b. The fifth end group 421a is the part on the positive Y-axis side when the multiple electrode plate ends 423 of the third electrode plate end group 421 are divided in half, and the sixth end group 421b is the part on the negative Y-axis side. The fourth electrode plate end group 422 has a seventh end group 422a and an eighth end group 422b. The seventh end group 422a is the part on the positive Y-axis side when the multiple electrode plate ends 423 of the fourth electrode plate end group 422 are divided in half, and the eighth end group 422b is the part on the negative Y-axis side.

In this way, the fifth end group 421a and the eighth end group 422b are arranged inside the electrode body end 420, and the sixth end group 421b and the seventh end group 422a are arranged outside the electrode body end 420. Since the electrode body end 420 has a wound electrode plate, the fifth end group 421a and the eighth end group 422b have the same inner plate end 423, and the sixth end group 421b and the seventh end group 422a have the same outer plate end 423. In other words, the fifth end group 421a and the eighth end group 422b do not have the same plate end 423 as the sixth end group 421b and the seventh end group 422a. Or, it can be said that the fifth end group 421a and the eighth end group 422b and the sixth end group 421b and the seventh end group 422a have different distances from the winding axis A. Specifically, the fifth end group 421a and the eighth end group 422b are positioned closer to the winding axis A than the sixth end group 421b and the seventh end group 422a.

With the above configuration, as shown in FIG. 4, the third electrode plate end group 421 is arranged at a position corresponding to the first electrode plate end group 411 (opposite side in the X-axis direction) protruding from the electrode body main body 430. The fifth end group 421a is arranged at a position corresponding to the second end group 411b (opposite side in the X-axis direction), and the sixth end group 421b is arranged at a position corresponding to the first end group 411a (opposite side in the X-axis direction). The fourth electrode plate end group 422 is arranged at a position corresponding to the second electrode plate end group 412 (opposite side in the X-axis direction) protruding from the electrode body main body 430. The seventh end group 422a is arranged at a position corresponding to the fourth end group 412b (opposite side in the X-axis direction), and the eighth end group 422b is arranged at a position corresponding to the third end group 412a (opposite side in the X-axis direction).

That is, the number of electrode plate ends 423 in the third electrode plate end group 421 is approximately the same as the number of electrode plate ends 413 in the first electrode plate end group 411, and the number of electrode plate ends 423 in the fourth electrode plate end group 422 is approximately the same as the number of electrode plate ends 413 in the second electrode plate end group 412. Also, the number of electrode plate ends 423 in the fifth end group 421a is approximately the same as the number of electrode plate ends 413 in the second end group 411b, and the number of electrode plate ends 423 in the sixth end group 421b is approximately the same as the number of electrode plate ends 413 in the first end group 411a. Furthermore, the seventh end group 422a has approximately the same number of plate ends 423 as the fourth end group 412b has, and the eighth end group 422b has approximately the same number of plate ends 423 as the third end group 412a has.

Then, the electrode connection portion 520 of the current collector 500 is connected (joined) to the first end group 411a of the first electrode plate end group 411 and the third end group 412a of the second electrode plate end group 412. Specifically, the multiple electrode plate ends 413 of the first end group 411a are bundled, the electrode connection portion 521 is arranged to sandwich the first end group 411a in the Y-axis direction, and the electrode connection portion 521 is joined to the first end group 411a by welding or the like. Also, the multiple electrode plate ends 413 of the third end group 412a are bundled, the electrode connection portion 522 is arranged to sandwich the third end group 412a in the Y-axis direction, and the electrode connection portion 522 is joined to the third end group 412a by welding or the like. The current collector 500 is not connected (joined) to the second end group 411b of the first electrode plate end group 411 and the fourth end group 412b of the second electrode plate end group 412.

Thus, the first end group 411a is a plurality of plate ends 413 that are joined to the current collector 500 (first current collector). The second end group 411b is a plurality of plate ends 413 that are not joined to the current collector 500 (first current collector). The third end group 412a is a plurality of plate ends 413 that are joined to the current collector 500 (first current collector). The fourth end group 412b is a plurality of plate ends 413 that are not joined to the current collector 500 (first current collector).

The electrode connection portion 620 of the current collector 600 is connected (joined) to the fifth end group 421a of the third electrode plate end group 421 and the seventh end group 422a of the fourth electrode plate end group 422. Specifically, the multiple electrode plate ends 423 of the fifth end group 421a are bundled together, the electrode connection portion 622 is arranged to sandwich the fifth end group 421a in the Y-axis direction, and the electrode connection portion 622 is joined to the fifth end group 421a by welding or the like. The multiple electrode plate ends 423 of the seventh end group 422a are bundled together, the electrode connection portion 621 is arranged to sandwich the seventh end group 422a in the Y-axis direction, and the electrode connection portion 621 is joined to the seventh end group 422a by welding or the like. The current collector 600 is not connected (joined) to the sixth end group 421b of the third electrode plate end group 421 and the eighth end group 422b of the fourth electrode plate end group 422.

Thus, the fifth end group 421a is a plurality of plate ends 423 that are joined to the current collector 600 (second current collector). The sixth end group 421b is a plurality of plate ends 423 that are not joined to the current collector 600 (second current collector). The seventh end group 422a is a plurality of plate ends 423 that are joined to the current collector 600 (second current collector). The eighth end group 422b is a plurality of plate ends 423 that are not joined to the current collector 600 (second current collector).

[3. Description of Effects]
As described above, according to the energy storage element 10 according to the embodiment of the present invention, the electrode body 400 has a first plate end group 411 and a second plate end group 412 at positions sandwiching the winding axis A at one end (electrode body end 410). The first plate end group 411 has a first end group 411a which is a plurality of plate ends 413 joined to the current collector 500 (first current collector), and a second end group 411b which is a plurality of plate ends 413 not joined to the current collector 500. In this way, instead of joining the current collector 500 to all the plate ends 413 of the first plate end group 411, the current collector 500 is joined to the first end group 411a, and the current collector 500 is not joined to the second end group 411b. This makes it possible to reduce the number of plate ends 413 joined to the current collector 500, thereby suppressing the occurrence of wrinkles in the plate. If the occurrence of wrinkles in the electrode plates can be suppressed, the thickness of the electrode plates can be suppressed from increasing, and therefore an increase in the reaction force occurring in the energy storage element 10 can be suppressed. If the increase in the reaction force can be suppressed, breakage of the electrode plates and damage to the module frame when the energy storage element 10 is modularized can be suppressed. The same applies to the second electrode plate end group 412. The same applies to the third electrode plate end group 421 and the fourth electrode plate end group 422 in the electrode body end 420.

In addition, in the electrode body 400, the second plate end group 412 has a third end group 412a joined to the current collector 500 and a fourth end group 412b not joined to the current collector 500, and the third end group 412a is arranged closer to the winding axis A than the first end group 411a. In this way, when the current collector 500 is joined to two places within the same circumference of the plate, the plate is likely to wrinkle, so the third end group 412a joined to the current collector 500 of the second plate end group 412 is arranged closer to the winding axis A than the first end group 411a joined to the current collector 500 of the first plate end group 411. In other words, the first end group 411a and the third end group 412a are arranged at positions with different distances from the winding axis A so that the first end group 411a and the third end group 412a are located on different circumferences of the plate. This can prevent the electrode plate from becoming wrinkled. In addition, since the current collector 500 is joined to different circumferences of the electrode plate, the current collection performance can be improved. Furthermore, by joining the current collector 500 to different circumferences of the electrode plate, the current collector 500 can be fixed more firmly to the electrode plate, improving vibration resistance and impact resistance. The same applies to the electrode body end 420 side (current collector 600 side).

The electrode body 400 also has a third electrode plate end group 421 at a position corresponding to the first electrode plate end group 411 at the other end (electrode body end 420). The third electrode plate end group 421 has a fifth end group 421a joined to the current collector 600 (second current collector) at a position corresponding to the second end group 411b, and a sixth end group 421b not joined to the current collector 600 at a position corresponding to the first end group 411a. In this way, when the current collectors 500, 600 are joined to both ends of the electrode body 400, wrinkles are likely to occur in the electrode plate, so the fifth end group 421a joined to the current collector 600 in the third electrode plate end group 421 is arranged at a position corresponding to the second end group 411b not joined to the current collector 500 in the first electrode plate end group 411. In addition, the sixth end group 421b in the third electrode plate end group 421 that is not joined to the current collector 600 is disposed at a position corresponding to the first end group 411a in the first electrode plate end group 411 that is joined to the current collector 500. In other words, when one end of the electrode body 400 is not joined to the current collector 500, the other end is joined to the current collector 600, and when one end of the electrode body 400 is joined to the current collector 500, the other end is not joined to the current collector 600. This makes it possible to prevent wrinkles from occurring in the electrode plate.

[4. Description of Modifications]
(Variation 1)
Next, a first modification of the above embodiment will be described. Fig. 5 is a cross-sectional view showing a connection configuration between the electrode assembly ends 410 and 420 of the electrode assembly 400 and the electrode connectors 520 (521A, 522A) and 620 (621A, 622A) of the current collectors 500 and 600 according to the first modification of the present embodiment. Fig. 5 corresponds to Fig. 4.

5, the first plate end group 411 of the electrode body end 410 in this modification has a first end group 411c and a second end group 411d instead of the first end group 411a and the second end group 411b of the first plate end group 411 of the electrode body end 410 in the above embodiment. The second plate end group 412 in this modification has a third end group 412c and a fourth end group 412d instead of the third end group 412a and the fourth end group 412b of the second plate end group 412 in the above embodiment. The third plate end group 421 of the electrode body end 420 in this modification has a fifth end group 421c and a sixth end group 421d instead of the fifth end group 421a and the sixth end group 421b of the third plate end group 421 of the electrode body end 420 in the above embodiment. The fourth electrode plate end group 422 in this modified example has a seventh end group 422c and an eighth end group 422d instead of the seventh end group 422a and the eighth end group 422b of the second electrode plate end group 412 in the above embodiment.

The current collector 500 in this modification has electrode connections 521A and 522A instead of the electrode connections 521 and 522 of the current collector 500 in the above embodiment. The current collector 600 in this modification has electrode connections 621A and 622A instead of the electrode connections 621 and 622 of the current collector 600 in the above embodiment. The rest of the configuration of this modification is the same as the above embodiment, so detailed description will be omitted.

The first end group 411c and the second end group 411d are formed so that the number of the plurality of electrode plate ends 413 of the first electrode plate end group 411 is greater in the first end group 411c than in the second end group 411d. The third end group 412c and the fourth end group 412d are formed so that the number of the plurality of electrode plate ends 413 of the second electrode plate end group 412 is greater in the fourth end group 412d than in the third end group 412c. In this embodiment, the number of the plurality of electrode plate ends 413 of the first end group 411c and the fourth end group 412d is approximately the same, and the number of the plurality of electrode plate ends 413 of the second end group 411d and the third end group 412c is approximately the same. In other words, the number of the electrode plate ends 413 of the third end group 412c is less than the number of the electrode plate ends 413 of the first end group 411c. Similarly, the number of electrode plate ends 413 in the second end group 411d is less than the number of electrode plate ends 413 in the fourth end group 412d.

As a result, the electrode connection portion 521A of the current collector 500 is arranged to sandwich the first end group 411c, which has a larger number of electrode plate ends 413, in the Y-axis direction, and the electrode connection portion 521A is joined to the first end group 411c by welding or the like. In addition, the electrode connection portion 522A is arranged to sandwich the third end group 412c, which has a smaller number of electrode plate ends 413, in the Y-axis direction, and the electrode connection portion 522A is joined to the third end group 412c by welding or the like.

Similarly, in the electrode body end 420, the sixth end group 421d has a larger number of electrode plate ends 423 than the fifth end group 421c, and the seventh end group 422c has a larger number of electrode plate ends 423 than the eighth end group 422d. As a result, the number of electrode plate ends 423 in the fifth end group 421c is smaller than the number of electrode plate ends 413 in the seventh end group 422c, and the number of electrode plate ends 423 in the eighth end group 422d is smaller than the number of electrode plate ends 423 in the sixth end group 421d. The electrode connection portion 621A of the current collector 600 is arranged to sandwich the seventh end group 422c, which has a larger number of electrode plate ends 423, in the Y-axis direction, and the electrode connection portion 621A is joined to the seventh end group 422c by welding or the like. In addition, the electrode connection portion 622A is arranged so as to sandwich the fifth end group 421c, which has a smaller number of electrode plate ends 423, in the Y-axis direction, and the electrode connection portion 622A is joined to the fifth end group 421c by welding or the like.

As described above, the energy storage element according to this modification can achieve the same effect as the above embodiment. In particular, in this modification, the number of electrode plate ends 413 in the third end group 412c is configured to be less than the number of electrode plate ends 413 in the first end group 411c in the electrode body 400. In this way, since the third end group 412c near the winding axis A of the electrode body 400 is more susceptible to wrinkles than the first end group 411c, the number of electrode plate ends 413 in the third end group 412c is made less than the number of electrode plate ends 413 in the first end group 411c. This makes it possible to suppress wrinkles from occurring in the third end group 412c, which is prone to wrinkles, and therefore to suppress wrinkles from occurring in the electrode plate as a whole. The same applies to the fifth end group 421c and the seventh end group 422c.

(Variation 2)
Next, a second modification of the above embodiment will be described. Fig. 6 is a cross-sectional view showing a connection configuration between an electrode body end portion 410 of an electrode body 400 and an electrode connection portion 520 (521, 522) of a current collector 500 according to the second modification of the present embodiment. Fig. 6 corresponds to the portion on the electrode body end portion 410 side in Fig. 4.

As shown in FIG. 6, in this modified example, the first end group 411a and the electrode connection portion 521 are joined to form the joint 710, and the third end group 412a and the electrode connection portion 522 are joined to form the joint 720. For example, the joint 710 is a cylindrical welded portion (melted portion) formed by welding the first end group 411a and the electrode connection portion 521 together, and the joint 720 is a cylindrical welded portion (melted portion) formed by welding the third end group 412a and the electrode connection portion 522 together.

The joint 720 also has a smaller width in the X-axis direction than the joint 710. In this modified example, the joint 720 also has a smaller width in the Z-axis direction than the joint 710. That is, the area of the joint 720 when viewed from the Y-axis direction is smaller than that of the joint 710, and therefore the volume of the joint 720 is smaller than that of the joint 710. In other words, the joint area of the joint 720 is smaller than that of the joint 710. The joint area is the area of the boundary surface between the end group and the electrode connection portion at the joint. That is, the third end group 412a has a smaller joint area with the current collector 500 (first current collector) than the first end group 411a.

Note that, as long as the joint area of joint 720 is smaller than that of joint 710, the shape of joints 710 and 720 is not limited to a cylindrical shape. In other words, joint 720 may have a larger width in the Z-axis direction than joint 710 if its width in the X-axis direction is sufficiently smaller, and may have a larger width in the X-axis direction than joint 710 if its width in the Z-axis direction is sufficiently smaller.

As in the above embodiment, the joining method at the joints 710 and 720 may be any type of welding, such as ultrasonic welding, laser welding, or resistance welding, or may be mechanical joining, such as crimping or screw fastening. Even if a method other than welding is used, the joining area is the area of the boundary surface between the end group and the electrode connection portion at the joining point.

Similarly, on the electrode body end 420 side, the joint between the fifth end group 421a and the electrode connection portion 622 is formed with a smaller joint area than the joint between the seventh end group 422a and the electrode connection portion 621. In other words, the fifth end group 421a has a smaller joint area with the current collector 600 (second current collector) than the seventh end group 422a.

As described above, the energy storage element according to this modification can achieve the same effect as the above embodiment. In particular, in this modification, the third end group 412a of the electrode body 400 is configured to have a smaller joint area with the current collector 500 (first current collector) than the first end group 411a. In this way, since the third end group 412a near the winding axis A of the electrode body 400 is more susceptible to wrinkles than the first end group 411a, the joint area with the current collector 500 is made smaller for the third end group 412a than for the first end group 411a. This makes it possible to suppress wrinkles from occurring in the third end group 412a, which is prone to wrinkles, and therefore to suppress wrinkles from occurring in the electrode plate as a whole. The same is true for the electrode body end 420 side.

(Other Modifications)
Although the embodiment and the modified examples of the present invention have been described above, the present invention is not limited to these embodiments and the modified examples. In other words, the disclosed embodiment and the modified examples are illustrative in all respects, and the scope of the present invention is defined by the claims, and includes all modifications within the meaning and scope equivalent to the claims.

For example, in the above embodiment and its modified examples, the electrode body 400 is a so-called vertically wound electrode body in which the winding axis is parallel to the lid body 120 (parallel to the X-axis direction). However, the electrode body 400 may be a so-called horizontally wound electrode body in which the winding axis is perpendicular to the lid body 120 (parallel to the Z-axis direction). Also, in the above embodiment and its modified examples, an oval shape is illustrated as the cross-sectional shape of the electrode body 400, but it may be an ellipse shape, a polygonal shape, or the like.

In the above embodiment and its modified example, the electrode body end 410 of the electrode body 400 has a plurality of plate ends 413, which are divided into two equal parts to form the first plate end group 411 and the second plate end group 412. However, the first plate end group 411 and the second plate end group 412 do not have to have the same number of plate ends 413, and may have different numbers of plate ends 413. The same applies to the third plate end group 421 and the fourth plate end group 422 of the electrode body end 420. The first end group and the second end group of the first plate end group 411 do not have to have the same number of plate ends 413, and may have different numbers of plate ends 413. The same applies to the two end groups of each of the second plate end group 412, the third plate end group 421, and the fourth plate end group 422.

In addition, in the above embodiment and its modified example, the electrode body end portion 410 has only two electrode plate end portions (the first electrode plate end portion 411 and the second electrode plate end portion 412), but it may have three or more electrode plate end portions. The same applies to the electrode body end portion 420. In addition, although each electrode plate end portion has only two end portions (for example, the first end portion and the second end portion), it may have three or more end portions.

In addition, in the above embodiment and its modified example, the first electrode plate end group 411 is a portion that protrudes from the center of the electrode body flat portion 431 in the Z axis direction. However, the first electrode plate end group 411 may be a portion that protrudes from the end of the electrode body flat portion 431 in the Z axis direction, or may be a portion that protrudes from the electrode body curved portion 432. The same applies to the second electrode plate end group 412, the third electrode plate end group 421, and the fourth electrode plate end group 422.

In addition, in the above embodiment and its modified example, in the first electrode plate end group 411, the first end group joined to the current collector 500 is arranged outside the second end group that is not joined to the current collector 500, but the first end group may be arranged inside the second end group.

In addition, in the above embodiment and its modified example, in the second plate end group 412, the third end group joined to the current collector 500 is arranged inside the fourth end group that is not joined to the current collector 500, but the third end group may be arranged outside the fourth end group. Also, the third end group does not have to be joined to the current collector 500, and the fourth end group may be joined to the current collector 500. The same applies to the third plate end group 421 and the fourth plate end group 422.

In addition, in the above embodiment and its modified example, the first end group does not have the same circumference of the plate end 413 as the third end group in the electrode body end 410, but the first end group may have the same circumference of the plate end 413 as the third end group. The same applies to the second end group and the fourth end group. The same applies to the electrode body end 420.

In addition, in the above embodiment and its modified example, the third end group in the electrode body end 410 has the same number of plate ends as the first end group or fewer than the first end group, but the third end group may have a greater number of plate ends than the first end group. The same applies to the electrode body end 420.

In addition, in the above embodiment and its modified example, the bonding area of the third end group with the current collector 500 in the electrode body end 410 is the same as or smaller than that of the first end group, but the bonding area of the third end group with the current collector 500 in the third end group may be larger than that of the first end group. The same applies to the electrode body end 420.

In the above embodiment and its modified example, the first electrode plate end group 411 and the third electrode plate end group 421 are arranged at corresponding positions on opposite sides in the X-axis direction and have the same number of electrode plate ends, but they may have different numbers of electrode plate ends. The first end group of the first electrode plate end group 411 and the sixth end group of the third electrode plate end group 421 may also have different numbers of electrode plate ends, and the second end group and the fifth end group may also have different numbers of electrode plate ends. The same applies to the second electrode plate end group 412 and the fourth electrode plate end group 422.

In the above embodiment and its modified example, the electrode connection parts of the current collectors 500, 600 are arranged to sandwich the end group of the electrode body ends 410, 420 of the electrode body 400 in the Y-axis direction, and the electrode connection parts and the end group are joined. However, the electrode connection parts may be arranged only on one side of the end group, and the electrode connection parts and the end group may be joined. In this case, a backing plate may be arranged at a position where the end group is sandwiched between the electrode connection parts. In other words, the shape of the current collectors 500, 600 is not particularly limited and may have any shape.

In addition, in the above embodiment and its modified example, the energy storage element is provided with one electrode body 400, but the number of electrode bodies 400 is not limited to one, and two or more may be provided. In this case, it is preferable that all electrode bodies 400 have the above-mentioned configuration, but it is not necessary that any of the electrode bodies 400 have the above-mentioned configuration.

In addition, configurations constructed by arbitrarily combining the components included in the above embodiments and their variations are also included within the scope of the present invention.

The present invention can be realized not only as such an energy storage element, but also as the electrode body 400 (and current collectors 500, 600 (first current collector, second current collector)) that the energy storage element includes.

The present invention can be applied to storage elements such as lithium ion secondary batteries.

10 Energy storage element 100 Container 200, 300 Electrode terminal 400 Electrode body 410, 420 Electrode body end 411 First electrode plate end group 411a, 411c First end group 411b, 411d Second end group 412 Second electrode plate end Part group 412a, 412c Third end group 412b, 412d Fourth end group 413, 423 Pole plate end 421 Third electrode plate end group 421a, 421c Fifth end group 421b, 421d Sixth end group 422 Fourth electrode plate end group 422a, 422c Seventh end group 422b, 422d Eighth end group 430 Electrode main body portion 431 Electrode body flat portion 432 Electrode body curved portion 500, 600 Current collector 520, 521, 521A, 522, 522A, 620, 621, 621A, 622, 622A: Electrode connection portion 710, 720: Joint portion

Claims (5)

An electric storage element including an electrode assembly in which an electrode plate is wound, and a first current collector connected to one end of the electrode assembly in a winding axis direction,
The electrode body is
An electrode body main body portion;
At the one end, a first electrode plate end group and a second electrode plate end group are disposed protruding from the electrode body main body at positions sandwiching a winding axis, and each of the first electrode plate end groups has a plurality of electrode plate ends of the electrode plates,
The first plate end group includes a first end group which is a plurality of plate ends joined to the first current collector, and a second end group which is a plurality of plate ends which are not joined to the first current collector. the second plate end group includes a third end group which is a plurality of plate ends joined to the first current collector, and a fourth end group which is a plurality of plate ends which are not joined to the first current collector,
The energy storage element according to claim 1 , wherein the third end group is disposed closer to the winding axis than the first end group. The energy storage element according to claim 2 , wherein the number of electrode plate ends in the third end group is smaller than the number of electrode plate ends in the first end group. The energy storage element according to claim 2 , wherein the third end portion group has a smaller bonding area with the first current collector than the first end portion group. Further, a second current collector is provided which is connected to the other end of the electrode assembly in the winding axis direction,
The electrode body has a third electrode plate end group arranged to protrude from the electrode body main body at a position corresponding to the first electrode plate end group at the other end,
the third plate end group includes a fifth end group which is a plurality of plate ends joined to the second current collector, and a sixth end group which is a plurality of plate ends which are not joined to the second current collector,
the fifth end group is disposed at a position corresponding to the second end group,
The energy storage element according to claim 1 , wherein the sixth end group is disposed at a position corresponding to the first end group.

Images