Power storage device and method for manufacturing power 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

Electricity storage device and method for manufacturing the same

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

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

[0003] US Patent Application Publication No. 2010 / 0216001

[0004] However, further improvement in the reliability of power storage devices is desired. In this situation, one of the objects of the present disclosure is to improve the reliability of power storage devices.

[0005] One aspect of the present disclosure relates to an energy storage device, the energy storage device including a first electrode having a strip-shaped first current collector and a first active material layer supported on the first current collector, a second electrode having a strip-shaped second current collector and 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 form a columnar wound body, the energy storage device further including a bottomed cylindrical case that houses the wound body, and a current collector plate disposed between the first electrode and a bottom of the case and electrically connected to both, wherein the first electrode has an overlapping region that overlaps with the current collector plate as viewed in an axial direction of the case and a non-overlapping region that does not overlap with the current collector plate as viewed in the axial direction, the first electrode and the current collector plate being electrically connected to each other in the overlapping region, and the first current collector of the first electrode is disposed in at least a portion of the non-overlapping region and has a contact portion that contacts the bottom of the case.

[0006] Another aspect of the present disclosure relates to a method for manufacturing an electric storage device, the method including: a first step of electrically connecting the first electrode of the wound body and the current collector plate in the overlapping region, a second step of accommodating the wound body and the current collector plate in the case and contacting the first current collector with a 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 the present disclosure, the reliability of the power storage device can be improved.

[0008] 6 is a longitudinal sectional view schematically illustrating an example of an electricity storage device according to the present disclosure. FIG. 6 is a perspective view of a wound body as viewed from the bottom side of the case. FIG. 7 is a perspective view of a wound body and a current collector plate as viewed from the bottom side of the case. FIG. 7 is a cross-sectional view of the electricity storage device taken along line IV-IV in FIG. 3, illustrating an enlarged view of the vicinity of the bottom of the case. FIG. 7 is a cross-sectional view of the electricity storage device taken along line V-V in FIG. 3, illustrating an enlarged view of the vicinity of the bottom of the case. FIG. 7 is a plan view of a jig used in a manufacturing method for an electricity storage device according to a first embodiment. FIG. 8 is an end view of a jig used in a manufacturing method for an electricity storage device according to a first embodiment, taken along line B-B. FIG. 9 is an end view of a jig used in a manufacturing method for an electricity storage device according to a first embodiment, taken along line C-C. FIG. 9 is an end view of a jig used in a manufacturing method for an electricity storage device according to a first embodiment, taken along line D-D. FIG. 10 is an end view for explaining a mode of use of the jig, corresponding to line B-B in FIG. 6. FIG. 11 is an end view for explaining a mode of use of the jig, corresponding to line D-D in FIG. 10A and 10B are views for explaining a method for manufacturing an electricity storage device according to a second embodiment, each showing a perspective view of a wound body; FIG. 10B are views for explaining a method for manufacturing an electricity storage device according to a second embodiment, each showing a perspective view of a wound body after a fourth step; FIG. 10C are views for explaining a method for manufacturing an electricity storage device according to a second embodiment, each showing a perspective view of a wound body after a fifth step;

[0009] An example of an embodiment of a power storage device and a method for manufacturing a power storage device according to the present disclosure will be described below. However, the present disclosure is not limited to the example described below. While specific numerical values ​​and materials are used in the following description, other numerical values ​​and materials may be used as long as the effects of the present disclosure are obtained.

[0010] (Electricity storage device) The electric energy storage device according to the present disclosure includes a strip-shaped first electrode, a strip-shaped second electrode, and a separator interposed therebetween. The first electrode, the second electrode, and the separator form a columnar wound body. That is, the first electrode and the second electrode are wound with the separator interposed therebetween.

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

[0012] The electricity storage device further includes a cylindrical case with a bottom that houses the wound body, and a current collector plate that is provided between the first electrode and the bottom of the case and 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 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 a region 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 the overlapping region. This connection may be achieved 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 adhesive bonding. The first electrode and the current collector plate may be electrically and mechanically connected to each other in the overlapping region.

[0015] 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. That is, the first current collector is connected to the bottom of the case via the current collector plate in the overlapping region, while in the non-overlapping region, the contact portion directly contacts the bottom of the case. Therefore, a path via the contact portion and the case is formed as a path for dissipating heat generated during charging and discharging from the first electrode, in addition to the conventional path via the current collector plate and the case. This improves the heat dissipation characteristics of the energy storage device and increases the reliability of the energy storage device. Furthermore, a current path usable for charging and discharging is formed between the contact portion and the bottom of the case, thereby reducing the resistance of the energy storage device. Note that the overlapping region and non-overlapping region may be formed at the end of the wound body on the sealing plate side of the energy storage device, and the contact portion may abut against the sealing plate or a conductive member electrically connecting the current collector plate and the sealing plate.

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

[0017] The contact portion may be bent in the radial direction of the case and be in surface contact with the bottom of the case. This configuration improves the heat transfer characteristics between the contact portion and the bottom of the case, further improving the heat dissipation characteristics of the power storage device. Furthermore, the contact portion in surface contact with the bottom of the case can stabilize the position of the wound body.

[0018] The contact portion may be bent radially inward of the case. For example, the contact portion may be formed by bending an end of the first current collector radially inward of the case. This makes it possible to easily form the contact portion while preventing the first electrode from being broken.

[0019] The current collector plate may have a connection portion that connects to the case and at least one arm portion that extends from the connection portion in a radial direction of the case and connects to the first electrode. Furthermore, the connection portion of the current collector plate may be located at the center and protrude further toward the bottom of the case than the arm portion. By using such a connection portion, the connection portion can be easily pressed against the bottom of the case from the wound body side toward the bottom of the case. Therefore, when the connection portion and the bottom of the case are welded and joined from the outside of the case, poor welding caused by the separation between the bottom of the case and the connection portion can be suppressed. Furthermore, the surface of the connection portion opposite the surface facing the bottom of the case may be recessed.

[0020] In the non-overlapping region of the first current collector, the length of a portion that extends from the connection point between the current collector plate and the first electrode toward the bottom of the case in the axial direction of the case 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 abut the bottom of the case with a bent tip (contact portion) of the first current collector in the axial direction.

[0021] The contact portion may be closer to the inside of the wound body than the outside in the radial direction of the case. Alternatively, the contact portion may be closer to the outside of the non-overlapping region than the inside in the circumferential direction of the case. This configuration makes it easier to form the contact portion in the non-overlapping region. It also makes it possible to densely pack the current collectors in the contact portion. It also makes it possible to suppress breakage of the first current collector in the non-overlapping region, improving the reliability of the energy storage device.

[0022] The non-overlapping region may be disposed radially outward of the contact portion and may include a region (non-contact region) that is farther 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 in the non-overlapping region, the circumferential dimension of the contact portion is smaller than that of the contact portion provided radially outward. This reduces circumferential tension on the current collector that constitutes the contact portion, making it less likely for the current collector that constitutes the contact portion to bend (or warp) radially, and making it easier to form a higher contact portion.

[0023] The first current collector may be bent in the radial direction of the case in the overlapping region and the non-overlapping region, with the bent portion in the overlapping region being longer than the bent portion in the non-overlapping region. In this configuration, the deformation of the first current collector in the overlapping region is small, which increases the rigidity of the overlapping region. When joining the current collector plate at this overlapping region, it is easier to obtain a reaction force from the first current collector when pressing the first current collector in the overlapping region via the current collector plate. This makes it easier to join the current collector plate and the first current collector in the overlapping region.

[0024] (Method for manufacturing an electricity storage device) A method for manufacturing an electricity storage device according to the present disclosure is the method for manufacturing the electricity storage device described above, and includes a first step, a second step, and a third step.

[0025] In a first step, the first electrode of the winding body is electrically connected to the current collector plate in the overlapping region of the first electrode. This connection may be achieved 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 adhesive bonding.

[0026] In the second step, the wound body and the current collector plate are housed in a case, and the first current collector is brought into contact with the bottom of the case in at least a part of the non-overlapping region of the first electrode to form a contact portion. The contact portion may be formed in advance before the wound body and the current collector plate are housed in the case, or may be formed by using the bottom of the case during the house-in 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 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 wound body. The jig may be used with the surface on which the recess is formed facing the first electrode. The current collector plate sandwiched between the jig and the wound body recesses the overlapping region of the first electrode according to the shape of the current collector plate. Meanwhile, the non-overlapping region of the first electrode is accommodated in the recess of the jig, and its end is bent while abutting against the bottom surface of the recess. This gives the non-overlapping region of the first electrode a shape corresponding to the contact portion that makes surface contact with the bottom of the case.

[0029] The method for manufacturing an electricity storage device may further include a fourth step, prior to the first to third steps, of pressing the first current collector in the overlapping region of the first electrode to cause the non-overlapping region to protrude beyond the overlapping region, and a fifth step, prior to the first to third steps, of pressing the first current collector in the non-overlapping region of the first electrode more shallowly than in the fourth step, to form a surface curved in the axial direction in the non-overlapping region. In the fourth step, the overlapping region may be pressed to correspond 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) may be used to press the first electrode in the fourth and fifth steps. Note that the order of execution of the fourth and fifth steps may be arbitrary, or both steps may be performed simultaneously.

[0030] As described above, the present disclosure can improve the reliability of the power storage device. Furthermore, the present disclosure can reduce the resistance of the power storage device. Furthermore, the present disclosure can stabilize the position of the wound body within the case.

[0031] An example of a power storage device and a method for manufacturing a power storage device according to the present disclosure will be described in detail below with reference to the drawings. The above-described components and processes can be applied to the components and processes of the example power storage device and the method for manufacturing a power storage device described below. The components and processes of the example power storage device and the method for manufacturing a power storage device described below can be modified based on the above description. Furthermore, the matters described below may be applied to the above-described embodiment. Of the components and processes of the example power storage device and the method for manufacturing a power storage device described below, components and processes that are not essential to the power storage device and the method for manufacturing a power storage device according to the present disclosure may be omitted. Note that the diagrams shown below are schematic and do not accurately reflect the shapes and numbers of actual components.

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

[0033] As shown in FIGS. 1 to 5 , the energy storage device 10 includes 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 form a columnar wound body 20. That is, the negative electrode 21 and the positive electrode 23 are wound with the separator 25 interposed therebetween. In the wound body 20, the negative electrode 21 and the positive electrode 23 are opposed to each other but shifted in the axial direction so that a positive electrode current collector exposed portion 24 a and a negative electrode current collector exposed portion 22 a, 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 longitudinal end of the negative electrode current collector 22, an negative electrode current collector exposed portion 22a that does not have the negative electrode active material layer is formed. 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-shaped metal material is used for the negative electrode current collector 22. The sheet-shaped metal material may be a metal foil, a porous metal, or the like. Examples of the metal material that can be used include copper, a copper alloy, 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 contains, for example, a negative electrode active material, a conductive agent, and a binder. The negative electrode active material layer is 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 absorbs 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. A positive electrode current collector exposed portion 24a that does not have a positive electrode active material layer is formed at one end along the longitudinal direction of the positive electrode current collector 24. 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-shaped metal material is used for the positive electrode current collector 24. The sheet-shaped metal material may be a metal foil, a porous metal, or the like. Examples of the metal material that can be used include aluminum, an 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 contains, 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 absorbs 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 strip-shaped and may be, for example, a microporous film made of a resin such as polyolefin, a woven fabric, a nonwoven fabric, etc. The thickness of the separator 25 is, for example, 10 μm or more and 300 μm or less, and preferably 10 μm or more and 40 μm or less.

[0041] The electricity storage device 10 further includes a cylindrical case 30 with a bottom that houses the wound body 20 , a negative electrode current collector plate 40 , a positive electrode current collector plate 50 , and a sealing plate 60 that seals the opening of the case 30 .

[0042] The case 30 is made of a metal material (e.g., aluminum). The case 30 may have a cylindrical shape with a bottom, but is not limited to this. The case 30 functions as a negative terminal of the power storage device 10.

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

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

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

[0046] The sealing plate 60 is made of a conductive material (e.g., metal). The sealing plate 60 is crimped to the edge of the opening of the case 30 via a gasket 80. With this configuration, the opening of the case 30 is sealed. The sealing plate 60 functions as a positive electrode terminal of the power storage device 10.

[0047] 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. In this embodiment, the overlapping region R1 is cross-shaped. In this embodiment, four non-overlapping regions R2 are formed, each of which is fan-shaped.

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

[0049] 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 negative electrode current collector exposed portion 22a, and is in surface contact with the bottom of the case 30. The contact portion 22b also extends radially inward of the case 30.

[0050] (Method for Manufacturing the Electric Storage Device) Next, a method for manufacturing the electric storage device 10 of this embodiment will be described. The manufacturing method includes a first step, a second step, and a third step.

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

[0052] In the first step of this embodiment, a jig 90 shown in FIGS. 6( a) to 6(d) is used. As shown in FIG. 6(a), the jig 90 is formed in the shape of a rectangular plate as a whole. As shown in FIGS. 6(a) to 6(d), the jig 90 has recesses 91 on one surface thereof that correspond to the non-overlapping region R2. In this embodiment, four recesses 91 are provided, each of which is fan-shaped. A slit 92 corresponding to the overlapping region R1 is formed between adjacent recesses 91. A pressing portion 93 for pressing the negative electrode current collector plate 40 is provided in the center of the jig 90.

[0053] 7A and 7B , in the first step, the negative electrode 21 and the negative electrode current collector 40 are electrically connected with each other in a state in which the negative electrode current collector 40 is sandwiched between the jig 90 and the wound body 20. This allows the negative electrode 21 and the negative electrode current collector 40 to be electrically connected with each other, while forming a bent portion (bent surface 22c) corresponding to the contact portion 22b at the end of the negative electrode current collector exposed portion 22a. Note that FIG. 7A shows a laser beam L used for laser welding.

[0054] In the second step, the wound body 20 and the negative electrode current collector 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 part 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 is electrically connected to the case 30. This electrical connection may be achieved by, for example, laser welding.

[0056] Second Embodiment A second embodiment of the present disclosure will be described. The method for manufacturing an electricity storage device of this embodiment differs from the first embodiment in that the jig 90 is not used. The following mainly describes the differences from the first embodiment.

[0057] The method for manufacturing an electricity storage device according to this embodiment includes 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] 8A and 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 to cause the non-overlapping region R2 to protrude beyond the overlapping region R1. For example, the fourth step may be performed by pressing a roller (not shown) against the negative electrode current collector exposed portion 22a and rolling the roller in the direction of the arrow in FIG.

[0059] 8B to 8C , in the fifth step, prior to the first to third steps, the negative electrode current collector 22 is pressed shallower in the non-overlapping region R2 of the negative electrode 21 than in the fourth step, thereby forming 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 negative electrode current collector exposed portion 22a and rolling the roller in the direction of the arrow in FIG.

[0060] The present disclosure can be used in an electricity storage device and a method for manufacturing an electricity storage device.

[0061] 10: Electricity storage device 20: Wound body 21: Negative electrode (first electrode) 22: Negative electrode current collector (first current collector) 22a: Negative electrode current collector exposed portion (first uncoated portion) 22b: Contact portion 22c: Bent surface 23: Positive electrode (second electrode) 24: Positive electrode current collector (second current collector) 24a: Positive electrode current collector exposed portion 25: Separator 30: Case 40: Negative electrode current collector (current collector) 41: Arm portion 42: Protrusion (connection portion) 50: Positive electrode current collector 60: Sealing plate 70: Lead 80: Gasket 90: Jig 91: Recess 92: Slit 93: Pressing portion L: Laser light R1: Overlapping region R2: Non-overlapping region

Claims

1. a first electrode having a strip-shaped first current collector and a first active material layer supported on the first current collector; a second electrode having a strip-shaped second current collector and 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 form a columnar wound body; a cylindrical case with a bottom that accommodates the wound body; a current collector plate provided between the first electrode and the bottom of the case and 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 a bottom portion of the case.

2. the first current collector has a first uncoated portion at one end in a lateral direction thereof where the first active material layer is not formed, In the wound body, the first electrode, the second electrode, and the separator are wound in a state in which the first uncoated portion protrudes from the second electrode in the axial direction of the case, The power storage device according to claim 1 , wherein the overlapping region and the non-overlapping region are formed by the first uncoated portion being wound.

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

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

5. 3 . The power storage device according to claim 1 , wherein the current collector plate has a connection portion that connects to the case, and at least one arm portion that extends from the connection portion in a radial direction of the case and connects to the first electrode.

6. 3. The energy storage device according to claim 1, wherein, in the axial direction of the case, a 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 a 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 power storage device according to claim 1 , wherein the contact portion is closer to an inner side than an outer side of the wound body in a radial direction of the case, or closer to an outer side than an inner side of the non-overlapping region in a circumferential direction of the case.

8. The power storage device according to claim 1 , wherein the non-overlapping region has a region that is disposed radially outward of the contact portion and farther from a bottom of the case than the contact portion.

9. 3 . The power storage device according to claim 1 , wherein the first current collector is bent in a 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 the electricity storage device according to claim 1 or 2, comprising: a first step of electrically connecting the first electrode of the wound body and the current collector plate in the overlapping region; a second step of housing the wound body and the current collector plate in the case and contacting the first current collector with a bottom of the case in at least a part of the non-overlapping region to form the contact portion; a third step of electrically connecting the current collector plate and the case; A method for manufacturing an electricity storage device, comprising:

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

12. a fourth step, prior to the first to third steps, of pressing down the first current collector in the overlapping region of the first electrode so that the non-overlapping region protrudes beyond the overlapping region; a fifth step, prior to the first to third steps, of pressing the first current collector shallower in the non-overlapping region of the first electrode than in the fourth step, to form a surface curved with respect to the axial direction in the non-overlapping region; The method for manufacturing an electricity storage device according to claim 10 , further comprising: