Electricity storage device

Abstract

A power storage device (10) is provided with: an electrode body (20) in which a positive electrode (21), a negative electrode (22), and a separator (23) are wound; a cover (41) disposed on the upper end side of the electrode body (20) in the winding axis direction of the electrode body (20); and a positive electrode tab (25) that connects the positive electrode (21) and the lid (41), the positive electrode tab (25) being joined to the lid (41), and the tip of the positive electrode tab (25) in the extending direction being covered by an insulating member (60).

Description

Technical Field

[0001] The present disclosure relates to a power storage device. Background Art

[0002] The power storage device is used as a power source for electric vehicles, etc. In recent years, with the popularization of electric vehicles, the cost reduction and productivity improvement of the power storage device are required. As the cost reduction and productivity improvement of the power storage device are accompanied by the enlargement of the power storage device, the power storage device is expected to have a high capacity and a high output.

[0003] In order to achieve high output of the power storage device, it is considered to reduce the internal resistance of the power storage device. For example, in Patent Document 1, the following multi-electrode tab structure technology is disclosed to reduce the internal resistance of the power storage device: a plurality of electrode tabs arranged in a long side direction of the strip electrode plate are provided on the strip electrode plate of the electrode body.

[0004] In the manufacturing process of the storage device with the above-mentioned multi-electrode lug structure, a long strip of electrode lugs is cut to produce a plurality of electrode lugs, and the plurality of electrode lugs produced are arranged and joined along the long side direction at the upper end of the strip electrode plate of the electrode body, and the strip electrode body is wound to produce a wound electrode body, and the plurality of electrode lugs protruding from the upper end are bent toward the center of the wound electrode body, and the wound electrode body is inserted into the outer can from the bottom side of the outer can, and a tool is inserted from the bottom side of the wound electrode body into the hollow portion in the center of the electrode body to ultrasonically join the plurality of electrode lugs and the cover.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2000-251871 Summary of the invention

[0008] Problem that the invention aims to solve

[0009] According to the above-mentioned power storage device, since power is collected by the multi-tab structure, the power collection resistance in the power storage device can be reduced. However, as a power storage device, further improvement in reliability is required.

[0010] Therefore, an object of the present disclosure is to provide a power storage device having excellent reliability.

[0011] Solutions for solving problems

[0012] The present disclosure provides a storage device, characterized in that the storage device comprises: an electrode body, which is formed by winding a positive electrode, a negative electrode and a separator; an external terminal, which is arranged on one end side of the electrode body in the winding axis direction of the electrode body; and a pole ear, which connects one of the positive electrode and the negative electrode to the external terminal, the pole ear is joined to the external terminal, and the top end of the pole ear in the extension direction is covered by an insulating member.

[0013] Effects of the Invention

[0014] According to the power storage device of the present disclosure, reliability can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic cross-sectional view of a power storage device as an example of the embodiment as viewed from the side.

[0016] Figure 2 It is a top view showing the electrode body before winding.

[0017] Figure 3 It is a perspective view showing the electrode body before the tab is bent.

[0018] Figure 4 is a top view of the electrode body.

[0019] Figure 5 It is a top view of an electrode body as another example of the embodiment.

[0020] Figure 6 It is a top view of an electrode body as another example of the embodiment. DETAILED DESCRIPTION

[0021] In the following description, specific shapes, materials, directions, numerical values, etc. are exemplified for easy understanding of the present disclosure and can be appropriately changed according to the application, purpose, specification, etc.

[0022] [Overall Structure of Power Storage Device]

[0023] use Figure 1 A power storage device 10 as an example of an embodiment will be described.

[0024] The power storage device 10 is mainly used as a power source for power. For example, the power storage device 10 is used as a power source for electric devices driven by electric motors, such as electric vehicles, electric tools, electric assisted bicycles, electric motorcycles, electric wheelchairs, electric tricycles, and electric vehicles for the elderly. However, the use of the power storage device 10 is not particularly limited, and it can also be used as a power source for various electric devices used indoors and outdoors, such as cleaners, wireless devices, lighting devices, digital cameras, or video cameras, etc., other than electric devices.

[0025] The power storage device 10 includes: an electrode body 20; an outer can 30 formed in a cylindrical shape and accommodating the electrode body 20; a sealing body 40 including a cap 41 as a positive electrode external terminal that seals one opening of the outer can 30; and a negative electrode collector plate 50 as a negative electrode external terminal that seals the other opening of the outer can 30. The outer can 30 contains the electrode body 20 and an electrolyte. The electrolyte may be an aqueous electrolyte, but in the present embodiment, a non-aqueous electrolyte is used. In the following, for convenience of description, the sealing body 40 side of the power storage device 10 is set as the upper side, and the negative electrode collector plate 50 side is set as the lower side.

[0026] The power storage device 10 also includes: a plurality of positive electrode tabs 25 extending from the upper end in the axial direction of the electrode body 20 (or also referred to as the winding axis direction) and connecting the positive electrode 21 and the cover 41 constituting the electrode body 20; and a negative electrode collector plate 50 arranged on the lower side in the axial direction of the electrode body 20, the negative electrode collector plate 50 being connected to the negative electrode 22 constituting the electrode body 20. In addition, in the power storage device 10 of the present disclosure, the electrode having the tab joined to the cover 41 may also be a negative electrode. In addition, the electrode that joins the collector plate and the exposed portion of the core body on the lower side of the power storage device 10 may also be a positive electrode. In addition, the power storage device 10 of the present embodiment does not have an upper insulating plate arranged between the electrode body 20 and the sealing body 40 (or the groove portion 30A), which will be described in detail later. However, the power storage device 10 may be provided with an upper insulating plate having a plurality of openings through which the positive electrode tabs 25 pass.

[0027] The electrode body 20, the positive electrode 21, the negative electrode 22 and the separator 23 are all strip-shaped long strips, which are spirally wound and alternately stacked in the radial direction of the electrode body 20. The innermost circumference of the electrode body 20 may have a hollow portion that penetrates in the axial direction. However, it is also possible that the hollow portion is not necessarily formed in the electrode body 20. In order to prevent the precipitation of lithium, the mixture layer of the negative electrode 22 is formed to be one size larger than the mixture layer of the positive electrode 21. That is, the mixture layer of the negative electrode 22 can be formed longer than the mixture layer of the positive electrode 21 in the long side direction and the width direction (short side direction). The separator 23 is formed to be at least one size larger than the positive electrode 21, for example, two separators 23 are arranged in a manner of sandwiching the positive electrode 21.

[0028] The positive electrode 21 has a strip-shaped positive electrode core and a positive electrode mixture layer formed on at least one surface of the core. For the positive electrode core, a foil of a metal such as aluminum or aluminum alloy that is stable within the potential range of the positive electrode 21, a film of the metal disposed on the surface, etc. can be used. The positive electrode mixture layer includes, for example, a positive electrode active material, a conductive agent such as acetylene black, and a binder such as polyvinylidene fluoride, and the positive electrode mixture layer is formed on both surfaces of the positive electrode core. For the positive electrode active material, for example, a lithium transition metal composite oxide is used.

[0029] The positive electrode tab 25 electrically connects the positive electrode 21 and the cover 41. The plurality of positive electrode tabs 25 are respectively connected to the positive electrode 21, but can also be directly joined to the positive electrode core by welding or the like. Therefore, it is also possible that the portion of the surface of the positive electrode core to which the positive electrode tab 25 is to be joined is not coated with a mixture layer. The plurality of positive electrode tabs 25 are directly joined to the lower surface of the raised portion 41A of the cover 41 of the sealing body 40. In addition, the positive electrode tab 25 may not be independent of the positive electrode core. For example, a portion of the positive electrode core may extend in a tongue-like shape to function as a positive electrode tab 25.

[0030] The negative electrode 22 has a strip-shaped negative electrode core and a negative electrode mixture layer formed on at least one surface of the core. For the negative electrode core, a foil of a metal such as copper or copper alloy that is stable within the potential range of the negative electrode 22, a film in which the metal is arranged on the surface, etc. can be used. Alternatively, the negative electrode mixture layer contains a binder such as a negative electrode active material and styrene-butadiene rubber (SBR), and the negative electrode mixture layer is formed on both surfaces of the negative electrode core. For the negative electrode active material, for example, graphite, silicon-containing compounds, etc. can be used. In the negative electrode 22, at one end in the short side direction of the negative electrode core, there is a core exposed portion formed by extending in the long side direction of the negative electrode core and not formed with a negative electrode mixture layer. The core exposed portion is configured in the axial direction to protrude to a position lower than the separator 23. The core exposed portion and the negative electrode collector plate 50 are joined by welding or the like, and the detailed joining method is described later.

[0031] The non-aqueous electrolyte comprises a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. For the non-aqueous solvent, for example, esters, ethers, nitriles, amides, and mixed solvents of two or more thereof can be used. The non-aqueous solvent may contain a halogen-substituted body obtained by replacing at least a portion of the hydrogen of these solvents with a halogen atom such as fluorine. As an example of a non-aqueous solvent, ethylene carbonate (EC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), and mixed solvents thereof can be cited. For the electrolyte salt, for example, a lithium salt such as LiPF6 can be used. In addition, the non-aqueous electrolyte may also be a gel electrolyte, a solid electrolyte, etc. instead of an electrolyte solution.

[0032] The outer can 30 is a cylindrical metal container with both ends open in the axial direction. In addition, examples of the metal constituting the outer can 30 include aluminum, copper, iron, nickel, and alloys thereof. The outer can 30 of the present embodiment is made of iron with a nickel-plated surface. In addition, the outer can 30 has an annular groove 30A formed along the circumferential direction. The groove 30A is formed near the upper end opening of the outer can 30 at a position separated from the upper end opening edge (the upper end of the outer can 30) by a predetermined length. The predetermined length is, for example, a length equivalent to 1% to 20% of the axial length of the outer can 30.

[0033] The groove portion 30A is a portion of the outer can 30 that extends outward from the inner side of the outer can 30. For example, the groove portion 30A is formed by spinning the outer can 30 from the outside. In addition, at the position where the groove portion 30A is formed, the outer can 30 is reduced in diameter, and a fine line-shaped groove is formed on the outer peripheral surface of the outer can 30. Alternatively, the groove portion 30A has a cross-section that is roughly U-shaped, and is formed in an annular shape over the entire circumferential length of the outer can 30. The groove portion 30A may be formed by processing after the electrode body 20 is housed in the outer can 30. In addition, the outer can 30 used in the power storage device 10 of the present disclosure is not limited to a structure in which a cylindrical container with openings at both ends and a collector plate are joined together. In particular, an outer can 30 in which one axial end is blocked by a bottom that is integral with the cylindrical portion may also be used.

[0034] The sealing body 40 has a cover 41 and a gasket 42, and is formed in a disc shape as a whole. The sealing body 40 is arranged on the groove portion 30A of the outer can 30 and is fixed to the upper end portion of the outer can 30. The upper end opening of the outer can 30 is bent radially inward and is fastened to the sealing body 40. In other words, the sealing body 40 is fixed to the upper end portion of the outer can 30 through the groove portion 30A and the fastening portion of the outer can 30, and the opening of the outer can 30 is blocked. The fastening portion is formed in an annular shape along the circumference of the outer can 30, and together with the groove portion 30A, the sealing body 40 is clamped in the axial direction through the gasket 42.

[0035] The cover 41, which serves as a positive electrode external terminal, is a disc-shaped metal member, which is exposed to the outside of the outer can 30 and forms the top surface of the power storage device 10. Examples of the metal constituting the cover 41 include aluminum, copper, iron, nickel, and alloys thereof. The cover 41 of the present embodiment is made of aluminum. The cover 41 has a shape (raised portion 41A) in which the radial center portion protrudes toward the outside of the power storage device 10. When the power storage device 10 is modularized to form a battery pack, wiring materials are connected to the cover 41. Therefore, the cover 41 functions as an external terminal of the power storage device 10, and is also referred to as an external terminal or a top cover. In the power storage device 10 of the present embodiment, a plurality of positive electrode tabs 25 are connected to the cover 41, and the cover 41 functions as a positive electrode external terminal.

[0036] The gasket 42 is provided between the outer periphery of the cover 41 and the outer can 30. The gasket 42 is a rubber member or a resin member for preventing contact between the cover 41 and the outer can 30 and ensuring electrical insulation between the outer can 30 and the sealing body 40. The gasket 42 seals the gap between the outer can 30 and the sealing body 40 to seal the interior of the power storage device 10. The gasket 42 has a disc-shaped base between the groove 30A and the lower surface of the cover 41 and a cylindrical wall connected to the outer periphery of the base and extending upward from the base. A positive electrode tab opening is formed at the center of the base. The wall covers the side circumference of the cover. In addition, the upper end of the wall is bent in a manner that is inverted radially inward through the upper end opening that is caulked. Through this bending, the upper end of the wall abuts against the upper surface of the cover 41. It is assumed that the electrolyte exists in the area of ​​the above-mentioned base of the gasket 42 that is opposite to the lower surface of the cover 41. Therefore, a through hole 42A is provided at the base of the gasket 42, thereby enabling the electrolyte to be efficiently returned to the electrode body 20 side. For example, a plurality of through holes 42A are formed along the circumferential direction of the gasket 42. In addition, in the power storage device 10, the through hole 42A is not necessarily required. In addition, the upper end of the cylindrical portion of the gasket 42 may also be referred to as an annular portion 42B extending from the outer peripheral portion of the cover 41 toward the center of the cover 41.

[0037] The negative electrode collector plate 50, which serves as a negative electrode external terminal, is disposed on the lower side of the electrode body 20 and is a disc-shaped metal plate made of nickel, a nickel alloy, or the like. The negative electrode collector plate 50 is, for example, made of an iron material whose surface is plated with nickel. The negative electrode collector plate may also be made of copper or an alloy containing copper. The outer peripheral edge of the negative electrode collector plate 50 is joined to the lower end opening of the outer can 30, thereby sealing the lower end opening of the outer can 30 to form the bottom portion of the outer can 30. In other words, the negative electrode collector plate 50 has the function of serving as a negative electrode external terminal and the function of the bottom portion of the outer can 30. The exposed portion of the core of the negative electrode 22 is joined to the negative electrode collector plate 50. A center hole 50A is provided in the negative electrode collector plate 50. The center hole 50A is sealed by a sealing plug 51 described later. In addition, the center hole 50A may overlap with the hollow portion of the electrode body 20 and the joint between the positive electrode tab 25 and the cover 41 in the axial direction. This overlapping makes it possible to easily form the joining portion.

[0038] The sealing plug 51 is a sealing member made of metal formed in a disc shape. In the present embodiment, a safety valve mechanism that operates when an abnormality occurs in the power storage device 10 is provided on the sealing plug 51. For example, a ring-shaped engraving may be formed on the sealing plug 51 as a safety valve mechanism. When an abnormality occurs in the power storage device 10 and the internal pressure rises, the engraving may be preferentially broken to form a gas discharge port in the sealing plug 51. Alternatively, an engraving may be provided on the negative electrode collector plate 50, and when the internal pressure of the power storage device 10 reaches a predetermined value or more, the engraving breaks to discharge gas. Furthermore, the sealing plug 51 may be formed of an elastic member and pressed into the center hole 50A.

[0039] [Positive electrode tab]

[0040] use Figure 2 to Figure 4 The positive electrode tab 25 as an example of an embodiment will be described in detail. Figure 2 The positive electrode tab 25 joined to the strip-shaped electrode body 20 before being wound is shown. Figure 3 The positive electrode tab 25 protruding upward from the wound electrode body 20 is shown. Figure 4 , the positive electrode tab 25 is shown to be bent on the upper surface of the wound electrode body 20 .

[0041] like Figure 2 As shown, the positive electrode tab 25 is a rectangular conductive member (such as aluminum). The positive electrode tab 25 electrically connects the positive electrode 21 and the cover 41 (see Figure 1 ). In more detail, one end side of the positive electrode tab 25 is bonded to the positive electrode 21, and the exposed portion 25B of the other end side other than the top end portion and not covered by the insulating member 60 is directly bonded to the lower surface of the raised portion 41A of the cover 41. In other words, the positive electrode tab 25 is directly bonded to the lower surface of the raised portion 41A of the cover 41 without passing through a current collecting member or the like.

[0042] By directly joining the positive electrode tab 25 to the cover 41, the number of components on the conductive path from the electrode body 20 to the cover 41 can be reduced. This can reduce the resistance value on the path from the electrode body 20 to the cover 41. As a result, the internal resistance value of the power storage device 10 can be reduced.

[0043] The positive electrode tab 25 is joined to the axial upper end of the positive electrode 21 of the strip-shaped electrode body 20 before winding. In the present embodiment, as an example, the power storage device 10 includes 8 positive electrode tabs 25. However, in the present disclosure, there is no limitation on the number of positive electrode tabs in the present embodiment. The power storage device 10 may also include 1 positive electrode tab 25. The power storage device 10 may also include 8 or more positive electrode tabs 25.

[0044] For the plurality of positive electrode tabs 25, the length of the positive electrode tabs 25 in the extension direction gradually increases from one side to the other side in the long side direction of the strip-shaped electrode body 20. Here, one side in the long side direction of the strip-shaped electrode body 20 becomes the center side of the electrode body after winding. On the other hand, the other side in the long side direction of the strip-shaped electrode body 20 becomes the outer peripheral side of the electrode body after winding. Figure 2In the embodiment, the length of the positive electrode tab 25 in the extension direction is along the axial direction. Thus, when the positive electrode tab 25 is bent on the upper surface of the wound electrode body 20, it is possible to suppress the positive electrode tabs 25 from interfering with each other. Here, interference means that when one positive electrode tab 25 is bent, the base end of the other positive electrode tab 25 is located below the one positive electrode tab 25.

[0045] In addition, among the plurality of positive electrode tabs 25, there are a first positive electrode tab 25 and a second positive electrode tab 25, and the first and second positive electrode tabs 25 are opposite to each other across the center of the upper surface of the electrode body 20. When the first positive electrode tab 25 is shorter than the second positive electrode tab 25, the dimension of the insulating member provided at the first positive electrode tab 25 in the extension direction of the positive electrode tab 25 may be smaller than the dimension of the insulating member provided at the second positive electrode tab 25 in the extension direction of the positive electrode tab 25. In addition, the dimension of the insulating member provided at the first positive electrode tab 25 in the width direction of the positive electrode tab 25 may be smaller than the dimension of the insulating member provided at the second positive electrode tab 25 in the width direction of the positive electrode tab 25. With the first positive electrode tab 25, when the exposed portions 25B of the first and second positive electrode tabs 25 are stacked, interference between the first positive electrode tab 25 and the second positive electrode tab 25 can be suppressed. At this time, when the exposed portion 25B of the first and second positive electrode tabs 25 is located closer to the electrode body than the exposed portion 25B of the second positive electrode tab 25 , interference can be particularly suppressed.

[0046] In addition, when the upper surface of the electrode body 20 is divided into two regions by a straight line passing through the center of the upper surface of the electrode body 20, the length of the positive electrode tab 25 arranged in the other region may be shorter than that of the positive electrode tab 25 arranged in one region. At this time, the dimension of the insulating member of the positive electrode tab 25 provided in the other region in the extension direction or width direction may be smaller than the dimension of the insulating member of the positive electrode tab 25 provided in one region in the extension direction or width direction. At this time, if the exposed portion 25B of the positive electrode tab 25 located in the other region is stacked closer to the electrode body than the exposed portion 25B of the positive electrode tab 25 located in one region, the above-mentioned interference can be particularly suppressed.

[0047] The positive electrode tab 25 is joined to the upper end of the positive electrode 21 of the strip-shaped electrode body 20 as described above. In addition, the positive electrode tab 25 protrudes toward the upper side of the axial direction of the strip-shaped electrode body 20. And the positive electrode tabs 25 are joined in a manner arranged at a predetermined interval along the long side direction of the strip-shaped electrode body 20. Here, the predetermined interval is determined, for example, in a manner that the positive electrode tabs 25 are substantially equiangular with each other when viewed from the axial direction when the strip-shaped electrode body 20 is wound (see Figure 3 and Figure 4 ).

[0048] like Figure 4 As shown, the plurality of positive electrode tabs 25 are arranged to extend radially from the center of the wound electrode body 20 when viewed from the axial direction. In addition, the exposed portions 25B of the plurality of positive electrode tabs 25 are stacked so as to partially overlap at the center of the wound electrode body 20 when viewed from the axial direction. In addition, a bonding portion 25A that is bonded to the lower surface of the raised portion 41A of the cover 41 is formed at the stacked portion of the exposed portions 25B.

[0049] [Insulation member]

[0050] like Figure 2 to Figure 4 As shown, the top end portion of the positive electrode tab 25 in the extension direction (long side direction) is covered by the insulating member 60. In more detail, the top end side of the positive electrode tab 25 in the extension direction is covered by the insulating member 60 except for the joint 25A. The insulating member 60 is formed in a substantially rectangular shape. The length of the insulating member 60 in the width direction (short side direction) can be longer than the length of the positive electrode tab 25 in the width direction. The top end side of the insulating member 60 in the long side direction can also be longer than the top end side of the positive electrode tab 25.

[0051] The insulating member 60 of the present embodiment is, for example, a sheet-shaped belt having insulating properties. However, the insulating member of the present invention is not limited to the insulating member 60 of the present embodiment. The insulating member may also be formed by sintering modified polypropylene having insulating properties. In addition, the insulating member may also be formed by a potting material, an adhesive, a UV curing agent, etc., each having insulating properties. In addition, the insulating member 60 only needs to cover at least a portion of the edge of the top end portion, and therefore, at the top end portion, the surface other than the edge may not be covered by the insulating member 60.

[0052] The base end portion of the positive electrode tab 25 in the extension direction is covered by the insulating member 61. In more detail, the base end side of the positive electrode tab 25 in the extension direction is covered by the insulating member 61 except for the joint 25A. The insulating member 61 is formed in a substantially rectangular shape. The length of the insulating member 61 in the width direction (short side direction) is preferably sufficiently longer than the length in the width direction of the positive electrode tab 25. The base end side of the insulating member 61 in the long side direction may also be slightly longer than the base end side of the positive electrode tab 25.

[0053] In the power storage device 10, when each positive electrode tab 25 is bent on the upper surface of the wound electrode body 20, the upper surface of the electrode body 20 (except the joint 25A of the positive electrode tab 25) is covered by the insulating member 60 and the insulating member 61. Thus, the electrode body 20 and the sealing body 40 can be electrically insulated.

[0054] Here, the positive electrode tab 25 is made by cutting a long strip of conductive member into a rectangular shape. During the cutting, a cutting burr may be formed at the cutting portion (e.g., the cross-section along the short side direction) formed at the edge of the top end of the positive electrode tab 25. When the positive electrode tab 25 and the cover 41 are ultrasonically bonded, the cutting burr may be peeled off from the positive electrode tab 25 and scattered due to ultrasonic vibration. As a result, the cutting burr may become a metal foreign body in the outer can 30, causing a voltage failure of the power storage device 10.

[0055] According to the insulating member 60 and the insulating member 61, it is possible to prevent the voltage failure of the power storage device 10. In more detail, by covering the top end of the positive electrode tab 25 with the insulating member 60 and covering the base end of the positive electrode tab 25 with the insulating member 61, when the positive electrode tab 25 and the cover 41 are ultrasonically bonded, it is possible to prevent the cutting burrs of the cut portion (the cross-section along the short side direction) of the top end of the positive electrode tab 25 from being peeled off and scattered from the positive electrode tab 25 due to ultrasonic vibration. Thus, it is possible to prevent the cutting burrs from becoming metal foreign matter in the outer can 30 and causing the voltage failure of the power storage device 10. In addition, the insulating member of the present invention may not be formed at both ends of the extension direction of the positive electrode tab 25. If an insulating member is arranged at least on the top side, the reliability is improved compared with the conventional power storage device.

[0056] In addition, if Figure 4 As shown, the insulating member 60 and the insulating member 61 can reduce the number of components of the power storage device 10 . More specifically, the insulating member 60 and the insulating member 61 can electrically insulate the electrode body 20 from the sealing body 40 .

[0057] [Other embodiments]

[0058] use Figure 5 and Figure 6 , the positive electrode tab 25 as another example of the embodiment is described in detail. Figure 5 and Figure 6 , the positive electrode tab 25 is shown bent above the wound electrode body 20 .

[0059] Hereinafter, the same configuration as that of the above-mentioned embodiment will be described as the same configuration as that of the above-mentioned embodiment and the description thereof will be omitted. In addition, the same components as those of the above-mentioned embodiment will be described using the same reference numerals as those of the above-mentioned embodiment.

[0060] like Figure 5As shown, in the present embodiment, the power storage device 10 has only one positive electrode tab 25. The top end of the positive electrode tab 25 in the long side direction is covered by the insulating member 60. More specifically, the top end side of the positive electrode tab 25 in the long side direction is covered by the insulating member 60 except for the joint 25A. The insulating member 60 is formed in a semicircular shape having substantially the same diameter as the upper surface of the electrode body 20 when viewed from the axial direction. In addition, in the insulating member 60, a notch 60A is formed in such a manner that the joint 25A formed in the exposed portion 25B is exposed when viewed from the axial direction.

[0061] The base end portion of the positive electrode tab 25 in the extension direction is covered by the insulating member 61. More specifically, the base end side of the positive electrode tab 25 in the long side direction is covered by the insulating member 61 except for the joint 25A. The insulating member 61 is formed in a semicircular shape having substantially the same diameter as the upper surface of the electrode body 20 when viewed from the axial direction. In addition, a notch 61A is formed in the insulating member 61 so that the joint 25A is exposed when viewed from the axial direction.

[0062] The insulating member 60 of the present embodiment is, for example, a sheet-like belt having insulating properties. However, the insulating member of the present invention is not limited to the insulating member 60 of the present embodiment. In the power storage device 10, when the positive electrode tab 25 is bent on the upper surface of the wound electrode body 20, the entire upper surface of the electrode body 20 (except for the joint 25A of the positive electrode tab 25 located at the exposed portion 25B) is covered by the insulating member 60 and the insulating member 61. Thus, the electrode body 20 can be electrically insulated from the sealing body 40.

[0063] According to the insulating member 60 and the insulating member 61 of the present embodiment, even when the power storage device 10 has only one positive electrode tab 25, the electrode body 20 and the sealing body 40 can be electrically insulated as described above, so there is no need to provide an upper insulating plate that is conventionally arranged between the electrode body 20 and the sealing body 40. However, in order to further improve reliability, an insulating plate may be provided between the insulating member 60 and the sealing body 40 and between the insulating member 60 and the electrode body 20 in the present embodiment.

[0064] like Figure 6As shown, in the present embodiment, the lengths of the positive electrode tabs 25 are the same. The positive electrode tabs 25 are joined in a manner of being arranged at a predetermined interval in the long side direction of the positive electrode 21 of the strip-shaped electrode body 20 (not shown). The predetermined interval is determined in a manner that the positive electrode tabs 25 are substantially at equal angles to each other when viewed from the axial direction when the strip-shaped electrode body 20 is wound. In addition, the predetermined interval can also be determined in a manner that another positive electrode tab 25 is not arranged on the side opposite to the center of the upper surface of the electrode body 20 of one positive electrode tab 25. By not arranging the positive electrode tab 25 on the opposite side of the predetermined positive electrode tab 25 across the above center, it is difficult for the positive electrode tab 25 on the opposite side to approach the predetermined positive electrode tab 25 from the opposite side, so that the predetermined positive electrode tab 25 is not easily interfered with when bending. Therefore, it is easy to freely design the size of the predetermined positive electrode tab 25 and the size of the insulating member provided on the positive electrode tab 25.

[0065] The tip side of the positive electrode tab 25 is covered by the insulating member 60 except the joint 25A. In addition, the base end side of the positive electrode tab 25 is covered by the insulating member 61 except the joint 25A. Moreover, the insulating member 60 and the insulating member 61 are rectangular in shape as in the above-mentioned embodiment. Moreover, the insulating member 60 and the insulating member 61 are formed of a tape having insulating properties.

[0066] In the power storage device 10, when the positive electrode tab 25 is bent on the upper surface of the wound electrode body 20, the entire upper surface of the electrode body 20 (except the joint 25A of the positive electrode tab 25) is covered by the insulating member 60 and the insulating member 61. Thus, the electrode body 20 and the sealing body 40 can be electrically insulated.

[0067] In the present embodiment, as described above, the positive electrode tab 25 is not disposed on the side of the positive electrode tab 25 opposite to the center of the electrode body 20. Therefore, when the positive electrode tab 25 is bent on the upper surface of the wound electrode body 20, even if the lengths of the positive electrode tabs 25 are the same, the positive electrode tabs 25 can be prevented from interfering with each other.

[0068] In addition, the present invention is not limited to the above-mentioned embodiment and its modified examples, and various changes and improvements can be made within the scope of the matters described in the claims of the present application. In the above-mentioned embodiment, the structure of the power storage device of the present invention is described using the positive electrode tab, but it is also possible to use a negative electrode tab instead of the above-mentioned positive electrode tab, and to set an insulating member on the negative electrode tab.

[0069] Description of Reference Numerals

[0070] 10. Power storage device; 20. Electrode body; 21. Positive electrode; 22. Negative electrode; 23. Spacer; 25. Positive electrode tab; 25A. Joint; 25B. Exposed portion; 27. Upper insulating plate; 30. External can; 30A. Groove; 40. Sealing body; 41. Cover (positive electrode external terminal); 41A. Raised portion; 42. Gasket; 42A. Through hole; 42B. Ring portion; 50. Negative electrode collector plate (negative electrode external terminal); 50A. Center hole; 51. Sealing plug; 60. Insulating member; 60A. Notch; 61. Insulating member; 61A. Notch.

Claims

1. A power storage device, wherein: The power storage device comprises: An electrode body, which is formed by winding a positive electrode, a negative electrode and a separator; an external terminal disposed on one end side of the electrode body in a winding axis direction of the electrode body; and a tab connecting one of the positive electrode and the negative electrode to the external terminal, The tab is engaged with the external terminal, The tip end portion of the electrode tab in the extending direction is covered by an insulating member.

2. The power storage device according to claim 1, wherein The power storage device comprises a plurality of the above-mentioned tabs. Each of the plurality of tabs has an exposed portion not covered by the insulating member at a position other than the top end in the extending direction. The exposed portions of the plurality of tabs overlap with each other, and the overlapping exposed portions are bonded to the external terminal.

3. The power storage device according to claim 2, wherein: A base end portion of the tab in the extending direction is covered by the insulating member.

4. The power storage device according to claim 3, wherein: The leading end side and the base end side of the tab in the extending direction are covered by the insulating member except for a portion joined to the external terminal.

5. The power storage device according to claim 4, wherein: One end surface of the electrode body in the winding axis direction is covered by the insulating member except for a portion where the electrode tab is joined to the external terminal.

6. The power storage device according to any one of claims 2 to 5, wherein: The tabs are arranged radially from a central portion of the external terminal.

7. The power storage device according to any one of claims 2 to 6, wherein: The adjacent electrode tabs are arranged at substantially the same angle.

8. The power storage device according to any one of claims 2 to 7, wherein: The lengths of the plurality of pole tabs in the extending direction are different.

9. The power storage device according to any one of claims 2 to 7, wherein: The other electrode tab is not arranged on a side of one electrode tab that is opposite to the center of the electrode body.

10. The power storage device according to any one of claims 2 to 7, wherein: One of the electrode tabs faces the other electrode tab across the center of the electrode body, and one of the electrode tabs is shorter than the other electrode tab.

11. The power storage device according to claim 10, wherein: The size of the insulating member provided at one of the electrode tabs is smaller than the size of the insulating member provided at the other electrode tab.

12. The power storage device according to claim 10, wherein: The exposed portion of one of the electrode tabs is stacked so as to be arranged closer to the electrode body than the exposed portion of the other electrode tab.

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