Energy storage device and method for manufacturing an energy storage device

Abstract

A power storage device according to the present invention includes: a first electrode having a first current collector, a second electrode having a second current collector, and a separator interposed between the first electrode and the second electrode. The first electrode, the second electrode, and the separator constitute a columnar wound body. The power storage device further includes a cylindrical bottomed case for accommodating the wound body, and a current collecting plate electrically connected to the first electrode and the case. The first electrode has an overlapping region that overlaps the current collecting plate when viewed in the axial direction of the case, and a non-overlapping region that does not overlap the current collecting plate when viewed in the axial direction. The first electrode and the current collecting plate are electrically connected to each other in the overlapping region. The first current collector includes a contact portion that is provided in at least a part of the non-overlapping region and that is in contact with the bottom of the case.

Description

Technical Field

[0001] The present disclosure relates to a power storage device and a method for manufacturing the power storage device.

Background Art

[0002] Conventionally, a power storage device including an electrode body having a current collector exposed at one end, a bottomed cylindrical case that houses the electrode body, and a current collecting plate provided between the electrode body and the bottom of the case is known (for example, Patent Document 1). In the power storage device of Patent Document 1, the current collecting plate is mechanically and electrically connected to the exposed current collector and the bottom of the case.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] By the way, further improvement in the reliability of the power storage device is desired. In such a situation, one of the objectives of the present disclosure is to improve the reliability of the power storage device.

[0005] One aspect of the present disclosure relates to an energy storage device. The energy storage device comprises a strip-shaped first current collector and a first electrode having a first active material layer supported on the first current collector, a strip-shaped second current collector and a second electrode having a second active material layer supported on the second current collector, and a separator interposed between the first electrode and the second electrode, wherein the first electrode, the second electrode, and the separator constitute a columnar winding body, and further comprises a bottomed cylindrical case housing the winding body, and a current collector plate provided between the first electrode and the bottom of the case and electrically connected to both, wherein the first electrode has an overlapping region that overlaps with the current collector plate when viewed from the axial direction of the case, and a non-overlapping region that does not overlap with the current collector plate when viewed from the axial direction, the first electrode and the current collector plate are electrically connected to each other in the overlapping region, and the first current collector of the first electrode has a contact portion provided in at least a part of the non-overlapping region and in contact with the bottom of the case.

[0006] Another aspect of the present disclosure relates to a method for manufacturing an energy storage device. The manufacturing method is a method for manufacturing an energy storage device as described above, comprising: a first step of electrically connecting the first electrode of the winding body and the current collector plate in the overlapping region; a second step of housing the winding body and the current collector plate in the case and bringing the first current collector into contact with the bottom of the case in at least a part of the non-overlapping region to form the contact portion; and a third step of electrically connecting the current collector plate and the case.

[0007] According to this disclosure, the reliability of energy storage devices can be improved. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic longitudinal cross-sectional view showing an example of an energy storage device related to this disclosure. [Figure 2] This is a perspective view of the reel, seen from the bottom of the case. [Figure 3] This is a perspective view of the winding body and current collector plate as seen from the bottom of the case. [Figure 4]Figure 3 is a cross-sectional view of the energy storage device along the IV-IV line, showing a magnified view of the area near the bottom of the case. [Figure 5] Figure 3 is a cross-sectional view of the energy storage device along the VV line, showing an enlarged view of the area near the bottom of the case. [Figure 6A] This is a plan view of a jig used in the manufacturing method of the energy storage device of Embodiment 1. [Figure 6B] This figure shows a jig used in the manufacturing method of the energy storage device of Embodiment 1, and is an end view along line BB. [Figure 6C] This figure shows a jig used in the manufacturing method of the energy storage device of Embodiment 1, and is an end view along the CC line. [Figure 6D] This figure shows a jig used in the manufacturing method of the energy storage device of Embodiment 1, and is an end view along the DD line. [Figure 7A] This diagram illustrates the usage of the jig and is an end view corresponding to line BB in Figure 6. [Figure 7B] This diagram illustrates the usage of the jig and is an end view corresponding to line DD in Figure 6. [Figure 8A] This is a diagram illustrating the manufacturing method of the energy storage device according to Embodiment 2, and is a perspective view of the wound body. [Figure 8B] This is a diagram illustrating the manufacturing method of the energy storage device according to Embodiment 2, and is a perspective view of the wound body after the fourth step. [Figure 8C] This is a diagram illustrating the manufacturing method of the energy storage device according to Embodiment 2, and is a perspective view of the wound body after the fifth step. [Modes for carrying out the invention]

[0009] Embodiments of the energy storage device and the method for manufacturing the energy storage device relating to this disclosure will be described below with examples. However, this disclosure is not limited to the examples described below. In the following description, specific numerical values ​​and materials may be given as examples, but other numerical values ​​and materials may be applied as long as the effects of this disclosure are achieved.

[0010] (Energy storage device) The energy storage device according to this disclosure comprises a strip-shaped first electrode, a strip-shaped second electrode, and a separator interposed between them. The first electrode, the second electrode, and the separator constitute a columnar wound body. That is, the first electrode and the second electrode are wound around each other with the separator in between.

[0011] The first electrode comprises a strip-shaped first current collector and a first active material layer supported on the first current collector. The second electrode comprises a strip-shaped second current collector and a second active material layer supported on the second current collector.

[0012] The energy storage device further comprises a bottomed cylindrical case for housing the above-mentioned wound body, and a current collector plate provided between the first electrode and the bottom of the case, which is electrically connected to both.

[0013] The first electrode has an overlapping region that overlaps with the current collector plate when viewed from the axial direction of the case (hereinafter also simply referred to as the axial direction), and a non-overlapping region that does not overlap with the current collector plate when viewed from the axial direction. The shape of the overlapping region corresponds to the shape of the current collector plate. For example, if the current collector plate has a cross shape, the overlapping region also has a cross shape. The non-overlapping region is the area of ​​the first electrode that is not included in the overlapping region when viewed from the axial direction.

[0014] The first electrode and the current collector plate are electrically connected to each other in their overlapping region. This connection may be implemented in various ways. For example, the first electrode and the current collector plate may be connected to each other by welding (e.g., laser welding), brazing, or bonding. The first electrode and the current collector plate may also be electrically and mechanically connected to each other in their overlapping region.

[0015] The first current collector of the first electrode is provided in at least a part of the non-overlapping region and has a contact portion that contacts the bottom of the case. That is, the first current collector is connected to the bottom of the case via the current collecting plate in the overlapping region, while directly contacting the bottom of the case at the contact portion in the non-overlapping region. For this reason, as a path for dissipating heat generated during charge and discharge from the first electrode, in addition to the path via the conventionally existing current collecting plate and the case, a path via the contact portion and the case is formed. Therefore, the heat dissipation characteristics of the power storage device can be improved, and the reliability of the power storage device can be enhanced. Furthermore, since a current path available for charge and discharge is formed between the contact portion and the bottom of the case, the power storage device can be made to have a lower resistance. Note that the overlapping region and the non-overlapping region may be formed at an end portion on the sealing plate side of the power storage device in the wound body, and the contact portion may contact the sealing plate or a conductive member that electrically connects the current collecting plate and the sealing plate.

[0016] The first current collector may have a first uncoated portion where the first active material layer is not formed at one end in its short side direction (or width direction). In the wound body, in the axial direction of the case, the first electrode, the second electrode, and the separator may be wound with the first uncoated portion protruding from the second electrode. The overlapping region and the non-overlapping region may be constituted by the wound first uncoated portion.

[0017] The contact portion may be bent in the radial direction of the case and in surface contact with the bottom of the case. According to this configuration, the heat transfer characteristics between the contact portion and the bottom of the case are enhanced, and the heat dissipation characteristics of the power storage device can be further improved. Furthermore, the posture of the wound body can be stabilized by the contact portion that is in surface contact with the bottom of the case.

[0018] The contact portion may be bent toward the inside in the radial direction of the case. For example, the contact portion may be formed by bending an end portion of the first current collector toward the inside in the radial direction of the case. Thereby, while suppressing the first electrode from being broken, the contact portion can be easily formed.

[0019] The current collector plate may have a connecting portion that connects to the case, and at least one arm portion that extends radially from the connecting portion in the case direction and connects to the first electrode. In the current collector plate, the connecting portion may be located in the center and protrude further toward the bottom of the case than the arm portion. By using such a connecting portion, the connecting portion can be easily pressed against the bottom of the case from the winding body side toward the bottom of the case. Therefore, when welding the connecting portion and the bottom of the case together from the outside of the case, welding defects that occur due to the separation between the bottom of the case and the connecting portion can be suppressed. In addition, the back surface of the connecting portion that faces the bottom of the case may be recessed.

[0020] In the axial direction of the case, the length of the portion of the first current collector in the non-overlapping region that extends toward the bottom of the case beyond the connection point between the current collector plate and the first electrode may be longer than the distance from the connection point between the current collector plate and the first electrode to the connection point between the current collector plate and the bottom of the case. This configuration makes it easy to bring the axial tip (contact portion) of the first current collector into contact with the bottom of the case in a bent state.

[0021] The contact area may be closer to the inside than the outside of the winding in the radial direction of the case. Alternatively, the contact area may be closer to the outside than the inside of the non-overlapping region in the circumferential direction of the case. This configuration allows for easier formation of the contact area in the non-overlapping region. Furthermore, the current collectors at the contact area can be made denser. In addition, breakage of the first current collector in the non-overlapping region can be suppressed, thereby increasing the reliability of the energy storage device.

[0022] The non-overlapping region may be located outside the contact portion in the radial direction of the case and may have a region (non-contact region) that is further from the bottom of the case than the contact portion. This configuration makes it easier to form the contact portion in the non-overlapping region. Furthermore, by providing the contact portion further inward in the radial direction of the case within the non-overlapping region, the circumferential dimension of the contact portion becomes smaller than that of a contact portion provided on the outside in the radial direction. As a result, circumferential tension is suppressed on the current collector constituting the contact portion, making it less likely for the current collector constituting the contact portion to bend (or warp) radially, and making it easier to form a higher contact portion.

[0023] The first current collector is bent radially in the case in the overlapping and non-overlapping regions, and the bent portion in the overlapping region may be longer than the bent portion in the non-overlapping region. In this configuration, the deformation allowance of the first current collector in the overlapping region is small, which makes it possible to increase the rigidity in the overlapping region. When joining the current collector plate in this overlapping region, it becomes easier to obtain a reaction force from the first current collector when pushing the first current collector in the overlapping region through the current collector plate. Therefore, joining the current collector plate and the first current collector in the overlapping region becomes easier.

[0024] (Manufacturing method for energy storage devices) The method for manufacturing an energy storage device according to this disclosure is the method for manufacturing an energy storage device described above, comprising a first step, a second step, and a third step.

[0025] In the first step, the first electrode of the winding body and the current collector plate are electrically connected in the overlapping region of the first electrode. This connection may be realized in various ways. For example, the first electrode and the current collector plate may be connected to each other by welding (e.g., laser welding), brazing, or bonding.

[0026] In the second step, the winding body and current collector plate are housed in the case, and the first current collector is brought into contact with the bottom of the case in at least a portion of the non-overlapping area of ​​the first electrode to form a contact portion. The contact portion may be formed in advance before housing the winding body and current collector plate in the case, or it may be formed using the bottom of the case during the housing process.

[0027] In the third step, the current collector plate and the case are electrically connected. This connection may be achieved in various ways. For example, the current collector plate and the case may be electrically connected by laser welding, ultrasonic welding, or brazing. The current collector plate and the case may also be electrically and mechanically connected.

[0028] In the first step, the first electrode and the current collector plate may be electrically connected with the current collector plate sandwiched between a jig having a recess corresponding to the non-overlapping region and the winding body. The jig may be used with the surface where the recess is formed facing the first electrode. The overlapping region of the first electrode is recessed according to the shape of the current collector plate by the current collector plate sandwiched between the jig and the winding body. On the other hand, the non-overlapping region of the first electrode is housed in the recess of the jig, and its end is bent in contact with the bottom surface of the recess. This gives the non-overlapping region of the first electrode a shape corresponding to a contact portion that makes surface contact with the bottom of the case.

[0029] The method for manufacturing the energy storage device may further include a fourth step, prior to the first to third steps, in which the first current collector is pressed down in the overlapping region of the first electrode to cause the non-overlapping region to protrude more than the overlapping region, and a fifth step, prior to the first to third steps, in which the first current collector is pressed down in the non-overlapping region of the first electrode to a shallower degree than in the fourth step to form a surface in the non-overlapping region that is bent in the axial direction. In the fourth step, the overlapping region may be pressed down in a manner corresponding to the shape of the current collector plate. In the fifth step, the non-overlapping region is given a shape corresponding to a contact portion that makes surface contact with the bottom of the case. Various tools (e.g., rollers) can be used to press down the first electrode in the fourth and fifth steps. Note that the order in which the fourth and fifth steps are performed does not matter; either step may come first, or both steps may be performed simultaneously.

[0030] As described above, this disclosure makes it possible to improve the reliability of the energy storage device. Furthermore, this disclosure makes it possible to reduce the resistance of the energy storage device. In addition, this disclosure makes it possible to stabilize the orientation of the winding body within the case.

[0031] Hereinafter, an example of an energy storage device and a method for manufacturing an energy storage device according to this disclosure will be specifically described with reference to the drawings. The components and processes described above can be applied to the components and processes of the example energy storage device and method for manufacturing an energy storage device described below. The components and processes of the example energy storage device and method for manufacturing an energy storage device described below can be modified based on the above description. Furthermore, the matters described below may be applied to the above embodiments. Among the components and processes of the example energy storage device and method for manufacturing an energy storage device described below, components and processes that are not essential to the energy storage device and method for manufacturing an energy storage device according to this disclosure may be omitted. Note that the figures shown below are schematic and do not accurately reflect the actual shape and number of components.

[0032] Embodiment 1 Embodiment 1 of the present disclosure will now be described. The energy storage device 10 in this embodiment is a lithium-ion secondary battery. However, the energy storage device 10 of the present disclosure is not limited thereto. For example, the energy storage device 10 may be a lithium-ion capacitor, an electric double-layer capacitor, an intermediate energy storage device between a lithium-ion secondary battery and a lithium-ion capacitor, or other electrochemical devices.

[0033] As shown in Figures 1 to 5, the energy storage device 10 comprises a strip-shaped negative electrode 21, a strip-shaped positive electrode 23, and a separator 25 interposed between the negative electrode 21 and the positive electrode 23. The negative electrode 21, the positive electrode 23, and the separator 25 constitute a columnar winding body 20. That is, the negative electrode 21 and the positive electrode 23 are wound around each other via the separator 25. In the winding body 20, the negative electrode 21 and the positive electrode 23 are offset in the axial direction and face each other such that the exposed positive electrode current collector portion 24a and the exposed negative electrode current collector portion 22a, which will be described later, protrude in opposite directions.

[0034] The negative electrode 21 has a strip-shaped negative electrode current collector 22 and a negative electrode active material layer (not shown) supported thereon. The negative electrode active material layer is formed on both sides of the negative electrode current collector 22. At one end of the negative electrode current collector 22 along the longitudinal direction, a negative electrode current collector exposed portion 22a is formed which does not have the negative electrode active material layer. The negative electrode 21 is an example of a first electrode. The negative electrode current collector 22 is an example of a first current collector. The negative electrode active material layer is an example of a first active material layer. The negative electrode current collector exposed portion 22a is an example of a first uncoated portion.

[0035] A sheet-like metal material is used for the negative electrode current collector 22. The sheet-like metal material can be a metal foil, a porous metal, or the like. Examples of metal materials include copper, copper alloys, nickel, and stainless steel. The thickness of the negative electrode current collector 22 is, for example, 10 μm or more and 100 μm or less.

[0036] The negative electrode active material layer includes, for example, a negative electrode active material, a conductive agent, and a binder. The negative electrode active material layer can be obtained, for example, by applying a negative electrode mixture slurry containing the negative electrode active material, a conductive agent, and a binder to both sides of the negative electrode current collector 22, drying the coating, and then rolling it. The negative electrode active material is a material that intercepts and releases lithium ions. Examples of negative electrode active materials include carbon materials, metal compounds, alloys, and ceramic materials.

[0037] The positive electrode 23 has a strip-shaped positive electrode current collector 24 and a positive electrode active material layer (not shown) supported thereon. The positive electrode active material layer is formed on both sides of the positive electrode current collector 24. At one end of the positive electrode current collector 24 along the longitudinal direction, a positive electrode current collector exposed portion 24a is formed which does not have the positive electrode active material layer. The positive electrode 23 is an example of a second electrode. The positive electrode current collector 24 is an example of a second current collector. The positive electrode active material layer is an example of a second active material layer.

[0038] A sheet-like metal material is used for the positive electrode current collector 24. The sheet-like metal material can be a metal foil, a porous metal, or the like. Examples of metal materials include aluminum, aluminum alloy, nickel, and titanium. The thickness of the positive electrode current collector 24 is, for example, 10 μm or more and 100 μm or less.

[0039] The positive electrode active material layer includes, for example, a positive electrode active material, a conductive agent, and a binder. The positive electrode active material layer can be obtained, for example, by applying a positive electrode mixture slurry containing the positive electrode active material, a conductive agent, and a binder to both sides of the positive electrode current collector 24, drying the coating, and then rolling it. The positive electrode active material is a material that intercepts and releases lithium ions. Examples of positive electrode active materials include lithium-containing transition metal oxides, transition metal fluorides, polyanions, fluorinated polyanions, and transition metal sulfides.

[0040] The separator 25 is in the shape of a strip and can be, for example, a microporous membrane made of a resin such as polyolefin, a woven fabric, or a nonwoven fabric. The thickness of the separator 25 is, for example, 10 μm or more and 300 μm or less, preferably 10 μm or more and 40 μm or less.

[0041] The energy storage device 10 further comprises a bottomed cylindrical case 30 that houses the winding body 20, a negative electrode current collector plate 40 and a positive electrode current collector plate 50, and a sealing plate 60 that seals the opening of the case 30.

[0042] Case 30 is made of a metal material (for example, aluminum). Case 30 may be a bottomed cylindrical shape, but is not limited to this. Case 30 functions as the negative terminal of the energy storage device 10.

[0043] The negative electrode current collector plate 40 is provided between the negative electrode 21 (or the winding body 20) and the bottom of the case 30. The negative electrode current collector plate 40 is electrically connected to the exposed portion 22a of the negative electrode current collector and the bottom of the case 30. The electrical connection between the exposed portion 22a of the negative electrode current collector and the negative electrode current collector plate 40 may be made, for example, by laser welding. The electrical connection between the bottom of the case 30 and the negative electrode current collector plate 40 may be made, for example, by ultrasonic welding. The negative electrode current collector plate 40 is an example of a current collector plate.

[0044] As shown in Figure 3, the negative electrode current collector plate 40 is formed in a cross shape overall. The negative electrode current collector plate 40 has a plurality of (four in this example) arm portions 41 extending along the radial direction of the case 30 and a projection portion 42 projecting toward the bottom of the case 30. The number of arm portions 41 may be three or fewer, or five or more. The negative electrode current collector plate 40 may be connected to the bottom of the case 30 at the projection portion 42. The negative electrode current collector plate 40 may have a ring-shaped portion connecting the tips of the plurality of arm portions 41. The projection portion 42 is an example of a connection portion.

[0045] The positive electrode current collector plate 50 is provided between the positive electrode 23 (or the winding body 20) and the sealing plate 60, and is electrically connected to the exposed portion 24a of the positive electrode current collector and the sealing plate 60. The electrical connection between the exposed portion 24a of the positive electrode current collector and the positive electrode current collector plate 50 may be made, for example, by laser welding. The connection between the sealing plate 60 and the positive electrode current collector plate 50 may be made via a metal lead 70.

[0046] The sealing plate 60 is made of a conductive material (for example, metal). The sealing plate 60 is crimped to the opening edge of the case 30 via a gasket 80. This configuration seals the opening of the case 30. The sealing plate 60 functions as the positive terminal of the energy storage device 10.

[0047] As shown in Figures 2 and 3, the negative electrode 21 has an overlapping region R1 that overlaps with the negative electrode current collector plate 40 when viewed from the axial direction of the case 30 (hereinafter also simply referred to as the axial direction), and a non-overlapping region R2 that does not overlap with the negative electrode current collector plate 40 when viewed from the axial direction. The overlapping region R1 in this embodiment is cross-shaped. The non-overlapping region R2 in this embodiment is formed of four, each being fan-shaped.

[0048] As shown in Figure 4, the negative electrode 21 and the negative electrode current collector plate 40 are electrically connected to each other in the overlapping region R1. This electrical connection may be made, for example, by laser welding performed along the longitudinal direction of each arm portion 41. In this case, the negative electrode 21 and the negative electrode current collector plate 40 are electrically and mechanically connected in the overlapping region R1.

[0049] As shown in Figure 5, the negative electrode current collector 22 is provided in at least a portion of the non-overlapping region R2 and has a contact portion 22b that contacts the bottom of the case 30. The contact portion 22b is located closer to the bottom of the case 30 than the joint between the arm portion 41 and the overlapping region R1. The contact portion 22b is formed by bending the end of the exposed portion 22a of the negative electrode current collector and is in surface contact with the bottom of the case 30. The contact portion 22b also extends radially inward from the case 30.

[0050] (Manufacturing method for energy storage devices) Next, a method for manufacturing the energy storage device 10 of this embodiment will be described. This manufacturing method comprises a first step, a second step, and a third step.

[0051] In the first step, the negative electrode 21 and the negative electrode current collector plate 40 are electrically connected in the overlapping region R1 of the negative electrode 21. This electrical connection may be made, for example, by laser welding performed along the longitudinal direction of each arm portion 41.

[0052] In the first step of this embodiment, the jig 90 shown in Figures 6(a) to 6(d) is used. As shown in Figure 6(a), the jig 90 is formed in the shape of a rectangular plate overall. As shown in Figures 6(a) to 6(d), the jig 90 has a recess 91 on one of its surfaces that corresponds to a non-overlapping region R2. In this embodiment, there are four recesses 91, each fan-shaped. Between adjacent recesses 91, a slit 92 corresponding to an overlapping region R1 is formed. A pressing portion 93 for holding down the negative electrode current collector plate 40 is provided in the center of the jig 90.

[0053] In the first step, as shown in Figures 7A and 7B, the negative electrode 21 and the negative electrode current collector 40 are electrically connected with the negative electrode 21 sandwiched between the jig 90 and the wound body 20. This enables the electrical connection between the negative electrode 21 and the negative electrode current collector 40 while forming a bent portion (bent surface 22c) corresponding to the contact portion 22b at the end of the exposed portion 22a of the negative electrode current collector. Note that Figure 7A shows the laser beam L used for laser welding.

[0054] In the second step, the winding body 20 and the negative electrode current collector plate 40 are housed in the case 30, and the negative electrode current collector 22 is brought into contact with the bottom of the case 30 in at least a portion of the non-overlapping region of the negative electrode 21 to form a contact portion 22b.

[0055] In the third step, the negative electrode current collector plate 40 and the case 30 are electrically connected. This electrical connection may be made, for example, by laser welding.

[0056] Embodiment 2 Embodiment 2 of this disclosure will now be described. The method for manufacturing the energy storage device in this embodiment differs from Embodiment 1 in that it does not use the jig 90 described above. The differences from Embodiment 1 will be mainly described below.

[0057] The manufacturing method of the energy storage device of this embodiment comprises a fourth step and a fifth step. In the following description, the fifth step is performed after the fourth step, but the order in which the two steps are performed is not limited to this.

[0058] In the fourth step, as shown in Figures 8A to 8B, prior to the first to third steps, the negative electrode current collector 22 is pressed down in the overlapping region R1 of the negative electrode 21, causing the non-overlapping region R2 to protrude more than the overlapping region R1. For example, the fourth step may be performed by pressing a roller (not shown) against the exposed portion 22a of the negative electrode current collector and rolling the roller in the direction of the arrow in Figure 8A.

[0059] In the fifth step, as shown in Figures 8B to 8C, prior to the first to third steps, the negative electrode current collector 22 is pressed down more shallowly than in the fourth step in the non-overlapping region R2 of the negative electrode 21 to form a surface (bent surface 22c) that is bent in the axial direction in the non-overlapping region R2. For example, the fifth step may be performed by pressing a roller (not shown) against the exposed portion 22a of the negative electrode current collector and rolling the roller in the direction of the arrow in Figure 8B. [Industrial applicability]

[0060] This disclosure can be used for energy storage devices and methods for manufacturing energy storage devices. [Explanation of symbols]

[0061] 10: Energy storage device 20: Coiled body 21: Negative electrode (first electrode) 22: Negative electrode current collector (first current collector) 22a: Exposed portion of the negative electrode current collector (first uncoated portion) 22b: Contact part 22c: Bent surface 23: Positive electrode (second electrode) 24: Positive electrode current collector (second current collector) 24a: Exposed part of positive electrode current collector 25: Separator 30: Case 40: Negative electrode current collector plate (current collector plate) 41: Arm section 42: Protruding part (connecting part) 50: Positive electrode current collector plate 60: Sealing plate 70: Lead 80: Gasket 90: Jig 91: Recess 92: Slit 93: Pressing part L: Laser light R1: Overlapping area R2: Non-overlapping area

Claims

1. A strip-shaped first current collector, and a first electrode having a first active material layer supported on the first current collector, A strip-shaped second current collector, and a second electrode having a second active material layer supported on the second current collector, A separator interposed between the first electrode and the second electrode, Equipped with, The first electrode, the second electrode, and the separator constitute a columnar wound body. A bottomed cylindrical case for housing the aforementioned wound body, A current collector plate is provided between the first electrode and the bottom of the case and is electrically connected to both, Furthermore, The first electrode has an overlapping region that overlaps with the current collector plate when viewed from the axial direction of the case, and a non-overlapping region that does not overlap with the current collector plate when viewed from the axial direction. The first electrode and the current collector plate are electrically connected to each other in the overlapping region. The first current collector of the first electrode is provided in at least a portion of the non-overlapping region and has a contact portion that contacts the bottom of the case, in an energy storage device.

2. The first current collector has a first uncoated portion at one end in its shorter direction where the first active material layer is not formed. In the winding body, the first electrode, the second electrode, and the separator are wound in such a way that the first uncoated portion protrudes from the second electrode in the axial direction of the case. The energy storage device according to claim 1, wherein the overlapping region and the non-overlapping region are composed of the wound first uncoated portion.

3. The energy storage device according to claim 1 or 2, wherein the contact portion is bent in the radial direction of the case and is in surface contact with the bottom of the case.

4. The energy storage device according to claim 1 or 2, wherein the contact portion is bent radially inward of the case.

5. The energy storage device according to claim 1 or 2, wherein the current collector plate has a connecting portion that connects to the case, and at least one arm portion that extends radially from the connecting portion in the case and connects to the first electrode.

6. The energy storage device according to claim 1 or 2, wherein, in the axial direction of the case, the length of the portion of the first current collector in the non-overlapping region that extends toward the bottom of the case beyond the connection point between the current collector plate and the first electrode is longer than the distance from the connection point between the current collector plate and the first electrode to the connection point between the current collector plate and the bottom of the case.

7. The energy storage device according to claim 1 or 2, wherein the contact portion is closer to the inside than the outside of the winding body in the radial direction of the case, or closer to the outside than the inside of the non-overlapping region in the circumferential direction of the case.

8. The energy storage device according to claim 1 or 2, wherein the non-overlapping region is located outside the contact portion in the radial direction of the case and is further from the bottom of the case than the contact portion.

9. The energy storage device according to claim 1 or 2, wherein the first current collector is bent in the radial direction of the case in the overlapping region and the non-overlapping region, and the bent portion in the overlapping region is longer than the bent portion in the non-overlapping region.

10. A method for manufacturing an energy storage device according to claim 1 or 2, In the overlapping region, a first step is to electrically connect the first electrode of the winding body and the current collector plate, A second step involves housing the winding body and the current collector plate in the case, and bringing the first current collector into contact with the bottom of the case in at least a portion of the non-overlapping area to form the contact portion, A third step involves electrically connecting the current collector plate and the case, A method for manufacturing an energy storage device, comprising the following:

11. A method for manufacturing an energy storage device according to claim 10, wherein in the first step, the current collector plate is sandwiched between a jig having a recess corresponding to the non-overlapping region and the winding body, and the first electrode and the current collector plate are electrically connected.

12. Prior to the first to third steps, a fourth step is taken in which the first current collector is pressed down in the overlapping region of the first electrode to cause the non-overlapping region to protrude more than the overlapping region, A fifth step is performed prior to the first to third steps, in which the first current collector is pressed down more shallowly than in the fourth step in the non-overlapping region of the first electrode to form a surface that is bent in the axial direction in the non-overlapping region, A method for manufacturing an energy storage device according to claim 10, further comprising:

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