Cylindrical battery

Abstract

This cylindrical battery comprises a wound-type electrode body (14), an outer can (16) that has a bottomed cylindrical shape and accommodates the electrode body (14), and a sealing body (17) that closes the opening of the outer can (16), and includes a plurality of positive electrode leads (20) connected to a positive electrode of the electrode body (14). The cylindrical battery further comprises a pressing member (30) that is disposed between the electrode body (14) and the sealing body (17) and presses the electrode body (14) via an insulating plate (18). The pressing member (30) is a conductive member to which the positive electrode leads (20) and the sealing body (17) are connected, and electrically connects the positive electrode leads (20) and the sealing body (17).

Description

Cylindrical battery

[0001] The present disclosure relates to cylindrical batteries.

[0002] A cylindrical battery generally includes a wound electrode assembly in which a positive electrode and a negative electrode are spirally wound with a separator interposed therebetween, a cylindrical outer can with a bottom that houses the electrode assembly, and a sealing member that closes the opening of the outer can, with a lead extending from the electrode assembly connected to the sealing member (see, for example, Patent Document 1). The outer can of a cylindrical battery is formed with an annular groove on its outer circumferential surface, and a grooved portion that protrudes radially inward on a portion of its inner circumferential surface. The grooved portion supports the sealing member and presses against the outer circumferential portion of the electrode assembly to prevent movement of the electrode assembly.

[0003] International Publication No. WO2022 / 270432

[0004] As described above, the grooved portion of the outer can contributes to suppressing displacement of the electrode assembly, but it is expected that the grooved portion alone will not be able to sufficiently suppress displacement of the electrode assembly when the battery is subjected to large vibrations, shocks, etc. In particular, as the diameter of a cylindrical battery increases, displacement of the electrode assembly becomes more likely, and misalignment of the relative positions of the positive electrode, negative electrode, and separator that make up the electrode assembly (so-called winding misalignment) may occur.

[0005] The cylindrical battery according to the present disclosure is a cylindrical battery comprising a wound electrode body, a bottomed cylindrical outer can that houses the electrode body, and a sealing body that closes the opening of the outer can, and including leads connected to electrodes that constitute the electrode body, and further comprising a pressing member that is disposed between the electrode body and the sealing body and presses the electrode body via an insulator, the pressing member being a conductive member that connects the lead and the sealing body, and electrically connects the lead and the sealing body.

[0006] The cylindrical battery according to the present disclosure can suppress the displacement of the electrode assembly inside the outer can and the occurrence of misalignment of the electrode assembly when wound. The configuration of the cylindrical battery according to the present disclosure is suitable for, for example, a large cylindrical battery with a large diameter.

[0007] Fig. 1 is a cross-sectional view of a cylindrical battery according to an example of an embodiment; Fig. 2 is a perspective view of the upper part of a cylindrical battery according to an example of an embodiment, showing a state before a sealing body is crimped and fixed; Fig. 3 is a view showing a first modified example of a pressing member; Fig. 4 is a view showing a second modified example of a pressing member; Fig. 5 is a view showing a third modified example of a pressing member;

[0008] Hereinafter, an example of an embodiment of a cylindrical battery according to the present disclosure will be described in detail with reference to the drawings. Note that configurations formed by selectively combining the components of the multiple embodiments and variations described below are included within the scope of the present disclosure.

[0009] Fig. 1 is a cross-sectional view of a cylindrical battery 10 according to an embodiment. As shown in Fig. 1, the cylindrical battery 10 includes a wound electrode assembly 14, an electrolyte, a cylindrical outer can 16 with a bottom that houses the electrode assembly 14 and the electrolyte, and a sealing member 17 that closes the opening of the outer can 16. The electrode assembly 14 includes a positive electrode 11, a negative electrode 12, and a separator 13, and has a wound structure in which the positive electrode 11 and the negative electrode 12 are spirally wound with the separator 13 interposed therebetween. Hereinafter, for convenience of explanation, the sealing member 17 side of the battery will be referred to as the top, and the bottom side of the outer can 16 will be referred to as the bottom.

[0010] The positive electrode 11, negative electrode 12, and separator 13 that make up the electrode assembly 14 are all long, strip-like bodies that are spirally wound and alternately stacked in the radial direction of the electrode assembly 14. The negative electrode 12 is formed to be slightly larger than the positive electrode 11 in order to prevent lithium precipitation. That is, the negative electrode 12 is formed to be longer than the positive electrode 11 in the longitudinal and width directions. The separator 13 is formed to be at least slightly larger than the positive electrode 11, and, for example, two separators 13 are arranged to sandwich the positive electrode 11. The electrode assembly 14 has a positive electrode lead 20 connected to the positive electrode 11 by welding or the like, and a negative electrode lead 21 connected to the negative electrode 12 by welding or the like.

[0011] As will be described in more detail below, the cylindrical battery 10 includes multiple positive electrode leads 20. The cylindrical battery 10 further includes a pressing member 30 that is disposed between the electrode body 14 and the sealing body 17 and presses the electrode body 14 via an insulator. The pressing member 30 is a conductive member to which the positive electrode leads 20 and the sealing body 17 are connected, and electrically connects the positive electrode leads 20 and the sealing body 17. In other words, the pressing member 30 functions as a positive electrode current collecting member that constitutes part of the current path of the positive electrode 11. Note that a negative electrode lead can also be connected to the pressing member, and the pressing member can also serve as a negative electrode current collecting member.

[0012] The positive electrode 11 has a positive electrode core and a positive electrode mixture layer disposed on the positive electrode core. The positive electrode core can be a foil of a metal that is stable within the potential range of the positive electrode 11, such as aluminum, an aluminum alloy, stainless steel, or titanium, or a film with such a metal disposed on the surface. The positive electrode mixture layer contains a positive electrode active material, a conductive agent, and a binder, and is preferably provided on both sides of the positive electrode core except for the portion to which the positive electrode lead 20 is connected. The positive electrode active material is a lithium transition metal composite oxide containing a transition metal element such as Ni, Co, or Mn.

[0013] The negative electrode 12 has a negative electrode core and a negative electrode mixture layer disposed on the negative electrode core. The negative electrode core can be a foil of a metal stable within the potential range of the negative electrode 12, such as copper, a copper alloy, stainless steel, nickel, or a nickel alloy, or a film having such a metal disposed on its surface. The negative electrode mixture layer contains a negative electrode active material and a binder, and is preferably provided on both sides of the negative electrode core except for the portion to which the negative electrode lead 21 is connected. The negative electrode active material generally uses a carbon material that reversibly absorbs and releases lithium ions. The negative electrode active material may also use an element that alloys with Li, such as Si or Sn, or a material containing such an element.

[0014] A porous sheet having ion permeability and insulating properties is used for the separator 13. Specific examples of the porous sheet include a microporous thin film, a woven fabric, and a nonwoven fabric. Suitable materials for the separator 13 include polyolefins such as polyethylene and polypropylene, and cellulose. The separator 13 may have a single-layer structure or a multi-layer structure. The separator 13 may have, for example, a multi-layer structure including a thermoplastic resin layer such as polyolefin and a cellulose fiber layer, a two-layer structure of polyethylene (PE) / polypropylene (PP), or a three-layer structure of PE / PP / PE.

[0015] The electrolyte may be an aqueous electrolyte, but in this embodiment, a non-aqueous electrolyte is used. The non-aqueous electrolyte has lithium ion conductivity. The non-aqueous electrolyte may be a liquid electrolyte (electrolytic solution) or a solid electrolyte.

[0016] The liquid electrolyte (electrolytic solution) contains a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. Examples of the non-aqueous solvent include esters, ethers, nitriles, amides, and mixed solvents of two or more of these. Examples of the non-aqueous solvent include ethylene carbonate (EC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and mixed solvents of these. The non-aqueous solvent may contain a halogen-substituted compound (e.g., fluoroethylene carbonate) in which at least a portion of the hydrogen atoms of these solvents are substituted with halogen atoms such as fluorine. Examples of the electrolyte salt include LiPF ６ Lithium salts such as

[0017] As the solid electrolyte, for example, a solid or gel-like polymer electrolyte, an inorganic solid electrolyte, etc. can be used. As the inorganic solid electrolyte, a material known in all-solid-state lithium ion secondary batteries, etc. (for example, an oxide-based solid electrolyte, a sulfide-based solid electrolyte, a halogen-based solid electrolyte, etc.) can be used. The polymer electrolyte includes, for example, a lithium salt and a matrix polymer, or a non-aqueous solvent, a lithium salt, and a matrix polymer. As the matrix polymer, for example, a polymer material that absorbs a non-aqueous solvent and gels is used. As the polymer material, for example, a fluororesin, an acrylic resin, a polyether resin, etc. can be used.

[0018] Insulating plates 18 and 19 are disposed above and below the electrode body 14. In the example shown in FIG. 1 , the positive electrode lead 20 passes through a through-hole in the insulating plate 18 and extends toward the sealing body 17, and the negative electrode lead 21 passes outside the insulating plate 19 and extends toward the bottom of the outer can 16. A pressing member 30 to which the multiple positive electrode leads 20 are connected is connected by welding or the like to the underside of an internal terminal plate 23 of the sealing body 17, and a cap 27, which is the top plate of the sealing body 17 and is electrically connected to the internal terminal plate 23, serves as the positive electrode terminal. The negative electrode lead 21 is connected by welding or the like to the inner bottom surface of the outer can 16, and the outer can 16 serves as the negative electrode terminal. The outer can 16 and the sealing body 17 are connected to an external circuit, for example, another battery constituting the battery module, a charger, or the like.

[0019] The outer can 16 is a cylindrical metal container with a bottom and an opening on one axial side, and the opening of the outer can 16 is closed by a sealing body 17. A gasket 28 is provided between the outer can 16 and the sealing body 17 to ensure airtightness inside the battery. The outer can 16 has a grooved portion 22 that supports the sealing body 17, with part of the side surface protruding inward. The grooved portion 22 is preferably formed in an annular shape along the circumferential direction of the outer can 16, and supports the sealing body 17 on its top surface. The sealing body 17 is fixed to the top of the outer can 16 by the grooved portion 22 and the open end of the outer can 16 that is crimped to the sealing body 17.

[0020] The sealing body 17 has a structure in which, in order from the electrode body 14 side, an internal terminal plate 23, a lower valve body 24, an insulating member 25, an upper valve body 26, and a cap 27 are stacked. Each member constituting the sealing body 17 has, for example, a disk or ring shape, and each member except for the insulating member 25 is electrically connected to one another. The lower valve body 24 and the upper valve body 26 are connected at their respective centers, and the insulating member 25 is interposed between their respective peripheral edges. When the internal pressure of the battery increases due to abnormal heat generation, the lower valve body 24 deforms and breaks, pushing the upper valve body 26 toward the cap 27, thereby interrupting the current path between the lower valve body 24 and the upper valve body 26. When the internal pressure further increases, the upper valve body 26 breaks, and gas is discharged from the opening of the cap 27.

[0021] The positive electrode lead 20 and the pressing member 30 will be described in detail below with further reference to Fig. 2. Fig. 2 is a perspective view of the upper part of the cylindrical battery 10, showing the state before the opening of the outer can 16 is sealed with the sealing body 17.

[0022] As shown in FIGS. 1 and 2 , the electrode assembly 14 includes a plurality of positive electrode leads 20 connected to the positive electrode 11. The plurality of positive electrode leads 20 extend from the upper end of the electrode group 14a constituting the electrode assembly 14 toward the sealing body 17 and are connected to a pressing member 30 disposed on the insulating plate 18. The electrode group 14a refers to a wound body consisting of the positive electrode 11, the negative electrode 12, and the separator 13, and a hollow portion 29 is formed in the winding core of the electrode group 14a. The hollow portion 29 is a space extending in the axial direction of the electrode group 14a. The pressing member 30 is a conductive member connected to the sealing body 17, and the positive electrode leads 20 are electrically connected to the sealing body 17 via the pressing member 30.

[0023] The positive electrode lead 20 is a rectangular conductive member, and is made of, for example, a metal containing aluminum as a main component. The material constituting the positive electrode lead 20 is preferably an aluminum alloy. The aluminum alloy is an alloy to which one or more other metal elements, such as copper, manganese, silicon, magnesium, zinc, or nickel, are added, and the electrical resistance, hardness, etc. of the material can be changed by adjusting the type and amount of the added element.

[0024] The width and thickness of the positive electrode lead 20 vary depending on the size, capacity, etc. of the battery, but an example of the width of the positive electrode lead 20 is 2 mm or more and 15 mm or less, or 3 mm or more and 10 mm or less. An example of the thickness of the positive electrode lead 20 is 0.03 mm or more and 0.15 mm or less, or 0.05 mm or more and 0.10 mm or less. The multiple positive electrode leads 20 may have different widths and thicknesses from one another, but in the example shown in FIG. 2 , all of the positive electrode leads 20 have substantially the same width and thickness.

[0025] The positive electrode lead 20 is welded to the core of the positive electrode 11. The positive electrode 11 has a plurality of core exposed portions spaced apart in the longitudinal direction of the positive electrode 11, where the positive electrode mixture layer is not present on the positive electrode core and the surface of the positive electrode core is exposed. One positive electrode lead 20 is connected to each exposed portion by welding or the like. The positive electrode lead 20 is generally joined to only one side of the positive electrode core, but the core exposed portions are provided on both sides of the positive electrode 11. The core exposed portions are formed, for example, to have substantially the same size so as to overlap in the thickness direction of the positive electrode 11. The welding position of the positive electrode lead 20 at each exposed portion is not particularly limited, and the positive electrode lead 20 is arranged within the range of the core exposed portion so as not to overlap with the positive electrode mixture layer.

[0026] In the embodiment illustrated in Fig. 2, three positive electrode leads 20 are provided, and thus core exposed portions are formed at three locations spaced apart in the longitudinal direction of the positive electrode 11. The spacing between each exposed portion may be constant or may vary. For example, the layout of the positive electrode leads 20 is appropriately set depending on the battery performance of the cylindrical battery 10, such as the capacity and output characteristics. Therefore, the spacing between each core exposed portion is determined depending on the layout, etc. The number of positive electrode leads 20 may be one, but is preferably multiple for large batteries, and may be, for example, 2 to 15.

[0027] The pressing member 30 is disposed between the electrode body 14 and the sealing body 17, and presses the electrode body 14 via the insulator, suppressing movement of the electrode body 14 within the outer casing 16 and suppressing misalignment of the electrode body 14. Because the outer periphery of the electrode body 14 can be pressed by the grooved portion 22, the pressing member 30 is preferably provided in a position that overlaps in the axial direction with a radially inner portion of the electrode body 14 that is separated from the grooved portion 22. In this embodiment, the outer casing 16 in which the grooved portion 22 is formed functions as a negative electrode terminal, and therefore the pressing member 30 is disposed so as not to come into contact with the grooved portion 22.

[0028] The pressing member 30 is a conductive member to which a plurality of positive electrode leads 20 are welded and which is welded to the sealing body 17, and functions as a positive electrode current collecting member. The constituent material of the pressing member 30 is not particularly limited, but the pressing member 30 is made of, for example, a metal containing aluminum as a main component, similar to the positive electrode leads 20. One suitable example of a constituent material of the pressing member 30 is an aluminum alloy. The pressing member 30 has a weld 32 to the sealing body 17 and a weld 31 to the positive electrode leads 20 formed thereon.

[0029] The pressing member 30 is disposed on the electrode body 14 via the insulating plate 18. The pressing member 30 is disposed on the insulating plate 18, but may be fixed to the insulating plate 18. The insulator interposed between the electrode body 14 and the pressing member 30 is not limited to the insulating plate 18, and may be, for example, an insulator constituting the electrode body 14 or the pressing member 30. Examples of insulators other than the insulating plate 18 include the separator 13 constituting the electrode body 14 and an insulating layer provided on the surface of the pressing member 30 facing the electrode body 14.

[0030] The pressing member 30 is disposed on the winding core (central axis) of the electrode body 14. In this embodiment, the electrode body 14 has a hollow portion 29 formed in the winding core, and the pressing member 30 is disposed on the hollow portion 29. That is, the pressing member 30 is provided at a position overlapping with the hollow portion 29 in the axial direction of the electrode body 14. The pressing member 30 has a width and length greater than the diameter of the hollow portion 29, and is disposed so as to cover, for example, the entire hollow portion 29 and the radially inner portion of the electrode body 14. Disposing the pressing member 30 on the winding core of the electrode body 14 can more effectively suppress displacement of the electrode body 14.

[0031] The pressing member 30 has a through hole 34 in a portion overlapping with the hollow portion 29. The hollow portion 29 in the electrode body 14 serves as an exhaust path when an abnormality occurs in the battery and gas is generated. For this reason, it is preferable to form the through hole 34 in the pressing member 30 to ensure an exhaust path. In other words, the through hole 34 functions as an air vent. The pressing member 30 is disposed so that at least a portion of the through hole 34 overlaps with the hollow portion 29 in the axial direction of the electrode body 14. In the example shown in FIG. 2 , the positive electrode lead 20 is welded around the through hole 34 of the pressing member 30 so as not to cover the through hole 34.

[0032] A plurality of welds 31 are formed on the pressing member 30 so as to surround the through-hole 34. The positive electrode lead 20 is welded to a first surface (upper surface) of the pressing member 30 facing the sealing body 17, or to a second surface (lower surface) of the pressing member 30 facing the electrode body 14, or to both the first and second surfaces. In the example shown in FIG. 2 , all of the positive electrode leads 20 are welded to the upper surface of the pressing member 30. In this case, good welds 31 can be easily formed, and the reliability of the welds 31 is also improved. The welds 31 may be formed on the hollow portion 29 of the electrode body 14. In this case, the welds 31 can be formed by inserting a jig used for welding into the hollow portion 29.

[0033] The through hole 34 is formed by passing through the pressing member 30 in the axial direction of the electrode body 14, and has a perfect circular shape in a planar view in the example shown in Fig. 2. A through hole is also formed in the insulating plate 18 at a position overlapping with the through hole 34. In a planar view of the electrode body 14 and the pressing member 30, the through hole 34 is larger than the hollow portion 29, and the pressing member 30 may be disposed on the electrode body 14 so that the entire hollow portion 29 is exposed through the through hole 34. The pressing member 30 is disposed, for example, so that the center of the through hole 34 overlaps with the central axis of the electrode body 14.

[0034] The pressing member 30 is a plate-like member having a larger cross-sectional area in the width direction than the positive electrode lead 20, has a bent portion 33 in the middle in the length direction, and is elastically deformed in the axial direction of the electrode body 14. As will be described in detail later, the pressing member 30 is disposed between the electrode body 14 and the sealing body 17 in a compressed state bent at the bent portion 33, and functions as a spring that presses the electrode body 14 via the insulating plate 18. The bent portion 33 is formed by bending the metal plate that constitutes the pressing member 30. The bent portion 33 is formed parallel to the width direction of the pressing member 30. The bent portion 33 may have a half-cut line, a notch, or the like. The bent portion 33 is formed in at least one location, but may be formed in multiple locations along the length of the pressing member 30.

[0035] The pressing member 30 is preferably wider and thicker than the positive electrode lead 20. On the other hand, the length of the pressing member 30 is not particularly limited and may be shorter than the positive electrode lead 20. The pressing member 30 is, for example, a metal plate having a substantially constant width and thickness over its entire length. The dimensions of the pressing member 30 can be changed appropriately depending on the size of the cylindrical battery 10, but for example, the width of the pressing member 30 is 10 mm to 30 mm, or 15 mm to 25 mm. The thickness of the pressing member 30 is, for example, 0.1 mm to 1.0 mm, or 0.2 mm to 0.5 mm.

[0036] The pressing member 30 has a width greater than a thickness. The ratio of the width to the thickness of the pressing member 30 is preferably 30 to 100 times, more preferably 40 to 90 times, and particularly preferably 50 to 80 times. In this case, the pressing member 30 can efficiently exhibit good spring properties. Note that, when at least one of the thickness and width of the pressing member 30 is not constant, it is sufficient that the ratio of the average width to the average thickness of the pressing member 30 or the ratio of the maximum width to the maximum thickness of the pressing member 30 is within the range.

[0037] The width direction cross-sectional area of ​​the pressing member 30 is larger than the width direction cross-sectional area of ​​the positive electrode lead 20, and is preferably 5 to 100 times the width direction cross-sectional area of ​​the positive electrode lead 20. More preferably, it is 10 to 50 times, and particularly preferably 15 to 30 times. In this case, the good spring properties of the pressing member 30 can be efficiently exhibited while suppressing defects such as contact between the outer can 16 and the pressing member 30 and a decrease in energy density. When the width direction cross-sectional area of ​​at least one of the positive electrode lead 20 and the pressing member 30 is not constant, it is sufficient that the ratio of the average values ​​or the maximum values ​​of the width direction cross-sectional areas of each member is within the relevant range. It is preferable to increase the width direction cross-sectional area of ​​the pressing member 30 by making both the thickness and width larger than those of the positive electrode lead 20.

[0038] The thickness of the pressing member 30 is, for example, 1.5 to 15 times, and preferably 2 to 10 times, the thickness of the positive electrode lead 20. When the thickness of at least one of the positive electrode lead 20 and the pressing member 30 is not constant, it is sufficient that the ratio of the average values ​​or the ratio of the maximum values ​​of the thicknesses of each member is within the range (the same applies to the widths). Furthermore, the width of the pressing member 30 is, for example, 1.5 to 10 times, and preferably 2 to 6 times, the width of the positive electrode lead 20.

[0039] The maximum width of the pressing member 30 is preferably 30% to 90% of the minimum inner diameter of the outer can 16, more preferably 35% to 80% and particularly preferably 40% to 70%. In this embodiment, the inner diameter of the outer can 16 is smallest at the portion where the grooved portion 22 is formed. If the ratio of the maximum width of the pressing member 30 to the minimum inner diameter of the outer can 16 is within this range, problems such as contact between the outer can 16 and the pressing member 30 and a decrease in energy density can be suppressed, while the pressing member 30 can efficiently exhibit good spring properties and the positive electrode lead 20 can also be easily welded.

[0040] The pressing member 30 is arranged such that a portion where a weld 31 to the positive electrode lead 20 is formed (hereinafter referred to as the "first region") is along the radial direction of the electrode body 14 on the insulating plate 18. Furthermore, a portion where a weld 32 to the sealing body 17 is formed (hereinafter referred to as the "second region") is arranged along the underside of the sealing body 17. In this embodiment, a bent portion 33 forms the boundary between the first region and the second region. The bent portion 33 is arranged radially outward of the outer can 16 relative to one longitudinal end of the pressing member 30 present in the first region, and is close to the grooved portion 22.

[0041] The width of the pressing member 30 may vary along the length. To prevent contact with the outer can 16 while increasing the width of the pressing member 30, the width of the pressing member 30 may be varied so that the width of the portion where the bent portion 33 is formed is smaller than that of the one end in the length direction. That is, the width of the pressing member 30 may be smaller at the portion where the bent portion 33 is formed than at the one end in the length direction on the electrode body 14 side. The width of the first region of the pressing member 30 may gradually decrease from the one end in the length direction toward the bent portion 33, or may be decreased in a stepwise manner at one or more locations. The width of the bent portion 33 of the pressing member 30 may be, for example, 90% or less, 30% to 80%, or 50% to 70% of the width at the one end in the length direction. The width of the second region of the pressing member 30 may be substantially the same as the width at the bent portion 33 throughout its entire length, or may be wider than the bent portion 33.

[0042] The pressing member 30 is bent, for example, at the bent portion 33 into an L-shape and has an L-shape when no external force is applied. When the sealing body 17 is crimped and fixed to the opening edge of the outer can 16, the pressing member 30 is bent at the bent portion 33 so that the first region and the second region face each other, and is disposed between the electrode body 14 and the sealing body 17 in a state compressed in the axial direction of the electrode body 14. In this case, the compressed pressing member 30 attempts to return to its original L-shape, functioning as a spring that presses the electrode body 14 via the insulating plate 18, and the pressing member 30 can apply a biasing force that presses the electrode body 14 from above. The first and second regions of the pressing member 30 may be disposed, for example, substantially parallel and facing each other with a small gap therebetween, and may sandwich the positive electrode lead 20 welded to the upper surface of the first region.

[0043] Another example of the embodiment will be described below with reference to Figures 3 to 5. In the following, the same components as those in the above embodiment will be designated by the same reference numerals and redundant description will be omitted.

[0044] The pressing member 30x illustrated in FIG. 3 has a protrusion 35, in which part of the edge of a through-hole 34x protrudes toward the center of the hole. A single positive electrode lead 20 is welded to the upper surface of the protrusion 35. Similar to the pressing member 30, the pressing member 30x is disposed such that the through-hole 34x overlaps with the hollow portion 29 in the axial direction of the electrode body 14. The pressing member 30x can form an exhaust path in the event of a battery abnormality while ensuring a welded location for the lead. The through-hole 34x is formed, for example, in a substantially C-shape in plan view. The shape of the through-hole is not limited to a perfect circle or a C-shape, and may be, for example, a polygonal, cross, semicircular, or the like.

[0045] The electrode body 14y illustrated in FIG. 4 differs from the electrode body 14 in that six positive electrode leads 20 are arranged in pairs overlapping each other. Furthermore, the pressing member 30y does not have a through-hole 34, and the tips of the six positive electrode leads 20 are welded to the upper surface of the pressing member 30y with their tips close to each other. The welded portion 31y is formed, for example, at a position overlapping with the hollow portion 29 in the axial direction of the electrode body 14. The pair of positive electrode leads 20 can be connected to the front and back of a single positive electrode core body with the core body sandwiched therebetween, but as shown in FIG. 4, it is preferable that the two positive electrode leads 20 extend from positions spaced apart in the radial direction of the electrode body 14y and aligned in the radial direction.

[0046] The embodiment illustrated in FIG. 5 is similar to the above-described embodiment in that it includes a pressing member 30z that is disposed between the electrode body 14 and the sealing body 17z and presses the electrode body 14 via an insulating plate 18, which is an insulator. The pressing member 30z is a conductive member to which the positive electrode lead 20 and the sealing body 17z are connected, and electrically connects the positive electrode lead 20 and the sealing body 17z. On the other hand, the pressing member 30z is a flat plate-like or block-like member that does not have a bent portion, and differs from the pressing members 30, 30x, and 30y in that it does not function as a spring that elastically deforms in the axial direction of the electrode body 14. Furthermore, the positive electrode lead 20 is welded only to the underside of the pressing member 30z.

[0047] The pressing member 30z does not apply a biasing force to the electrode body 14, but is pressed from above by the sealing body 17z, and this force presses the electrode body 14 via the insulating plate 18, suppressing displacement and winding misalignment of the electrode body 14. The sealing body 17z presses the pressing member 30z from above by being crimped and fixed to the opening edge of the outer can 16. The weld between the sealing body 17z and the pressing member 30z can be formed, for example, by irradiating a laser beam from the top surface of the sealing body 17z. In the example shown in FIG. 5 , a through hole 34z is formed in the pressing member 30z at a portion that overlaps with the hollow portion 29 of the electrode body 14.

[0048] As described above, in a cylindrical battery having the above configuration, the pressing member presses the radially inner portion of the electrode body 14 from above, effectively suppressing displacement of the electrode body 14 within the outer can 16 and the occurrence of winding misalignment of the electrode body 14. The outer periphery of the electrode body 14 is pressed by the grooved portion 22, and the radially inner portion near the winding core is pressed by the pressing member. The above configuration is particularly suitable for large cylindrical batteries in which the diameter of the electrode body 14 is large.

[0049] When a folded metal plate is placed in a compressed state between the electrode body 14 and the sealing body 17, as in the case of the pressing member 30, the pressing member 30 functions as a spring that elastically deforms in the axial direction of the electrode body 14, and can apply a biasing force that presses down on the electrode body 14 from above. In this case, displacement of the electrode body 14 can be effectively suppressed, the pressing member 30 can be made thinner and lighter, and the assembly and dimensional design of the battery are also easier.

[0050] The above-described embodiments may be appropriately modified without departing from the scope of the present disclosure, and may be modified by selectively combining the components of the above-described embodiments. For example, in the embodiment illustrated in Fig. 2, the number of positive electrode leads 20 may be six, as in the embodiment illustrated in Fig. 4. It is also possible to arrange multiple pressing members between the electrode body and the sealing body.

[0051] The present disclosure is further described by the following embodiments. Configuration 1: A cylindrical battery comprising a wound electrode assembly, a cylindrical outer can with a bottom that houses the electrode assembly, and a sealing body that closes the opening of the outer can, and including a lead connected to the electrode assembly, further comprising a pressing member disposed between the electrode assembly and the sealing body and pressing the electrode assembly via an insulator, the pressing member being a conductive member to which the lead and the sealing body are connected, and electrically connecting the lead and the sealing body. Configuration 2: The cylindrical battery according to Configuration 1, wherein the pressing member is a plate-shaped member having a widthwise cross-sectional area larger than that of the lead, has a bent portion in the middle in the lengthwise direction, and elastically deforms in the axial direction of the electrode assembly. Configuration 3: The cylindrical battery according to Configuration 1 or 2, wherein the widthwise cross-sectional area of ​​the pressing member is 5 to 100 times the widthwise cross-sectional area of ​​the lead. Configuration 4: The cylindrical battery according to any one of Configurations 1 to 3, wherein the maximum width of the pressing member is 30% to 90% of the minimum inner diameter of the outer can.Configuration 5: The cylindrical battery according to any one of Configurations 1 to 4, wherein the ratio of the width to the thickness of the pressing member is 50 to 100 times.Configuration 6: The cylindrical battery according to Configuration 2, wherein the width of the pressing member is smaller at the portion where the bent portion is formed than at one end in the longitudinal direction on the electrode body side.Configuration 7: The cylindrical battery according to any one of Configurations 1 to 6, wherein the electrode body has a hollow portion formed in a winding core, and the pressing member is disposed above the hollow portion and has a through-hole in the portion overlapping with the hollow portion. Configuration 8: The cylindrical battery of any one of Configurations 1 to 7, wherein the lead is welded to a first surface of the pressing member facing the sealing body, welded to a second surface of the pressing member facing the electrode body, or welded to both the first and second surfaces.

[0052] REFERENCE SIGNS LIST 10 Cylindrical battery, 11 Positive electrode, 12 Negative electrode, 13 Separator, 14 Electrode body, 14a Electrode group, 16 Outer can, 17 Sealing body, 18, 19 Insulating plate, 20 Positive electrode lead, 21 Negative electrode lead, 22 Grooved portion, 23 Internal terminal plate, 24 Lower valve body, 25 Insulating member, 26 Upper valve body, 27 Cap, 28 Gasket, 29 Hollow portion, 30 Pressing member, 31, 32 Welded portion, 33 Bent portion, 34 Through hole

Claims

1. A cylindrical battery comprising a wound electrode body, a cylindrical outer can with a bottom that houses the electrode body, and a sealing body that closes the opening of the outer can, and including a lead connected to an electrode that constitutes the electrode body, and further comprising a pressing member that is disposed between the electrode body and the sealing body and presses the electrode body via an insulator, the pressing member being a conductive member to which the lead and the sealing body are connected, and electrically connecting the lead and the sealing body.

2. The cylindrical battery according to claim 1, wherein the pressing member is a plate-like member having a larger cross-sectional area in the width direction than the lead, has a bent portion in the middle in the length direction, and is elastically deformable in the axial direction of the electrode body.

3. The cylindrical battery according to claim 2, wherein the cross-sectional area in the width direction of the pressing member is 5 times or more and 100 times or less than the cross-sectional area in the width direction of the lead.

4. The cylindrical battery according to claim 2, wherein the maximum width of the pressing member is 30% or more and 90% or less of the minimum inside diameter of the outer can.

5. The cylindrical battery according to claim 2, wherein the ratio of the width to the thickness of the pressing member is 30 times or more and 100 times or less.

6. The cylindrical battery according to claim 2, wherein the width of the pressing member is smaller at the portion where the bent portion is formed than at one end in the longitudinal direction of the electrode body side.

7. A cylindrical battery as described in claim 1 or 2, wherein the electrode body has a hollow portion formed in a winding core, and the pressing member is disposed above the hollow portion and has a through hole in the portion overlapping with the hollow portion.

8. A cylindrical battery according to any one of claims 1 to 7, wherein the lead is welded to a first surface of the pressing member facing the sealing body, welded to a second surface of the pressing member facing the electrode body, or welded to both the first and second surfaces.

Images