Cylindrical battery

Abstract

A cylindrical battery comprises: an electrode body; an electrolytic solution; a bottomed cylindrical outer can that accommodates the electrode body and the electrolytic solution; a sealing body that closes an opening of the outer can; and an upper insulating plate (18) that is disposed between the electrode body and the sealing body. A positive electrode lead (20) is connected to the sealing body. The upper insulating plate (18) has a plurality of through-holes (30, 31, 32). In a plan view of the upper insulating plate (18), hole walls (35, 36) of the through-holes (30, 31) are inclined with respect to the thickness direction of the upper insulating plate (18) such that the area of second openings (30b, 31b) in a lower surface (18b) is less than the area of first openings (30a, 31a) in an upper surface (18a).

Description

Cylindrical battery

[0001] The present disclosure relates to a cylindrical battery, and more particularly to a cylindrical battery provided with an upper insulating plate.

[0002] Conventionally, a cylindrical battery comprising a bottomed cylindrical outer can that houses an electrode body and an electrolyte, a sealing body that closes an opening of the outer can, and an upper insulating plate disposed between the electrode body and the sealing body has been widely known (see, for example, Patent Document 1). Generally, a lead extending from the positive electrode or the negative electrode of the electrode body is connected to the sealing body, and the sealing body functions as an external terminal for the positive electrode or the negative electrode. The upper insulating plate prevents, for example, contact between the lead and the counter electrode of the electrode body.

[0003] In the manufacturing process of a cylindrical battery, after the electrode body and the upper insulating plate are housed in the outer can, the electrolyte is injected into the outer can. For this reason, a through hole for allowing the electrolyte to pass through is formed in the upper insulating plate. This through hole also functions as a vent for allowing gas to pass through when an abnormality occurs in the battery. Furthermore, a through hole for passing the lead to the sealing body side is also formed in the upper insulating plate.

[0004] Japanese Unexamined Patent Publication No. 2020-149821

[0005] As described above, since a plurality of through holes are formed in the upper insulating plate, for example, when a strong impact is applied to the battery, a part of the lead connected to the sealing body may enter the through hole from the sealing body side, contact the counter electrode of the electrode body, and cause a short circuit.

[0006] The cylindrical battery according to this disclosure comprises an electrode body, an electrolyte, a bottomed cylindrical outer container housing the electrode body and the electrolyte, a sealing body that closes the opening of the outer container, and an upper insulating plate disposed between the electrode body and the sealing body, wherein leads extending from the positive or negative electrode constituting the electrode body are connected to the sealing body, and the upper insulating plate has a through hole that penetrates from a first opening on a first surface facing the sealing body side to a second opening on a second surface facing the electrode body side, and at least one of the plurality of through holes is characterized in that, in a plan view of the upper insulating plate viewed from a direction perpendicular to the first surface, the area of ​​the second opening is smaller than the area of ​​the first opening, the hole wall of the through hole is inclined with respect to the thickness direction of the upper insulating plate.

[0007] According to the cylindrical battery described herein, contact between the lead connected to the sealing body and the counter electrode of the electrode body can be more reliably prevented without impairing the function of the through-hole in the upper insulating plate.

[0008] This is a cross-sectional view of a cylindrical battery, which is an example of an embodiment. This is a plan view (a) and a cross-sectional view (b) of the upper insulating plate, which is an example of an embodiment. This is a diagram showing a modified example of the upper insulating plate, which is a plan view (a) and a cross-sectional view (b) of the upper insulating plate, which is a cross-sectional view (b) of the upper insulating plate.

[0009] Hereinafter, an example of an embodiment of the cylindrical battery according to this disclosure will be described in detail with reference to the drawings. Note that the cylindrical battery according to this disclosure is not limited to the embodiments described below. Furthermore, forms obtained by selectively combining the various components of the multiple embodiments and modifications described below are also included in this disclosure.

[0010] Figure 1 is a schematic diagram showing an axial cross-section including the central axis of a cylindrical battery 10, which is an example of an embodiment. As shown in Figure 1, the cylindrical battery 10 comprises an electrode body 14, an electrolyte, a bottomed cylindrical outer container 16 that houses the electrode body 14 and the electrolyte, and a sealing body 17 that closes the opening of the outer container 16. The outer container 16 has grooves 22 formed on its side surface, and the sealing body 17 is supported by the grooves 22 and closes the opening of the outer container 16. In the following, for convenience of explanation, the side of the cylindrical battery 10 with the sealing body 17 will be considered the top, and the bottom side of the outer container 16 will be considered the bottom. The outer container 16 is a bottomed cylindrical metal container with one axial end (upper end) open, and the upper end opening of the outer container 16 is closed by the sealing body 17.

[0011] The electrolyte may be an aqueous electrolyte, but in this embodiment, a non-aqueous electrolyte is used. The non-aqueous electrolyte has, for example, lithium-ion conductivity. The cylindrical battery 10 is a non-aqueous electrolyte secondary battery, and among these, a lithium-ion battery is preferred.

[0012] A non-aqueous electrolyte comprises a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. Examples of non-aqueous solvents include esters, ethers, nitriles, amides, and mixtures of two or more of these. Examples of non-aqueous solvents include ethylene carbonate (EC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and mixtures thereof. The non-aqueous solvent may also contain halogen-substituted solvents (e.g., fluoroethylene carbonate) in which at least some of the hydrogen atoms of the solvent are replaced with halogen atoms such as fluorine. Examples of electrolyte salts include LiPF4. ６ Lithium salts such as these are used.

[0013] The electrode body 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 wound in a spiral shape via the separator 13. The cylindrical battery 10 has a structure in which leads extending from the positive electrode 11 or the negative electrode 12 constituting the electrode body 14 are connected to a sealing body 17. In this embodiment, a positive electrode lead 20 extending from the positive electrode 11 is connected to the sealing body 17, and the sealing body 17 becomes the positive electrode terminal. As will be described in detail later, since the positive electrode lead 20 is placed on the wound structure of the electrode body 14, it is necessary to insulate the positive electrode lead 20 and the negative electrode 12 of the electrode body 14 from each other so that they do not come into contact.

[0014] The positive electrode 11, the negative electrode 12, and the separator 13 are all elongated strip-shaped bodies that are alternately stacked in the radial direction of the electrode body 14 by being wound in a spiral shape. The negative electrode 12 is formed to be slightly larger than the positive electrode 11 in order to prevent lithium deposition. That is, the negative electrode 12 is formed to be longer in both the length and width directions than the positive electrode 11. The separator 13 is formed to be at least slightly larger than the positive electrode 11, and two of them are arranged, for example, so as to sandwich the positive electrode 11. The electrode body 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.

[0015] The positive electrode 11 comprises a positive electrode core and a positive electrode mixture layer provided on the positive electrode core. The positive electrode core can be made of a metal foil that is stable within the potential range of the positive electrode 11, such as aluminum, aluminum alloy, stainless steel, or titanium, or a film with the metal arranged on its 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, excluding the portion to which the positive electrode lead 20 is connected. The positive electrode active material is a lithium transition metal composite oxide containing transition metal elements such as Ni, Co, and Mn.

[0016] The negative electrode 12 comprises a negative electrode core and a negative electrode mixture layer provided on the negative electrode core. The negative electrode core can be made of a metal foil that is stable within the potential range of the negative electrode 12, such as copper, copper alloy, stainless steel, nickel, or nickel alloy, or a film with the metal arranged 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. Generally, a carbon material that reversibly intercepts and releases lithium ions is used as the negative electrode active material. The negative electrode active material may also be an element that alloys with Li, such as Si or Sn, or a material containing such an element.

[0017] The separator 13 is made of a porous sheet having ion permeability and insulating properties. Specific examples of porous sheets include microporous thin films, woven fabrics, and nonwoven fabrics. Suitable materials for the separator 13 include polyethylene, polyolefins such as polypropylene, and cellulose. The separator 13 may have a single-layer structure or a multi-layer structure. For example, the separator 13 may have 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.

[0018] The cylindrical battery 10 includes an upper insulating plate 18 positioned between the electrode body 14 and the sealing body 17. The cylindrical battery 10 also includes a lower insulating plate 19 positioned between the electrode body 14 and the inner surface of the bottom of the outer casing 16. In other words, insulating plates are positioned above and below the electrode body 14. In this embodiment, the positive electrode lead 20 extends towards the sealing body 17 through a through hole 30 in the upper insulating plate 18, and the negative electrode lead 21 extends towards the bottom of the outer casing 16 through the outside of the lower insulating plate 19. The positive electrode lead 20 is connected to the lower surface of the internal terminal plate 23 of the sealing body 17 by welding or the like, and the cap 27, which is the top plate of the sealing body 17 and is electrically connected to the internal terminal plate 23, becomes the positive electrode terminal. The negative electrode lead 21 is connected to the inner surface of the bottom of the outer casing 16 by welding or the like, and the outer casing 16 becomes the negative electrode terminal.

[0019] The positive electrode lead 20 extends between the sealing body 17 and the upper insulating plate 18, along the first surface of the upper insulating plate 18 facing the sealing body 17, and is folded back and connected to the sealing body 17. In the manufacturing process of the cylindrical battery 10, after welding the positive electrode lead 20 to the sealing body 17, the sealing body 17 is placed on the grooved portion 22 of the outer casing 16. Therefore, it is necessary to ensure a certain length of the positive electrode lead 20, and a bent portion 20a is formed on the positive electrode lead 20.

[0020] A gasket 28 is provided between the outer casing 16 and the sealing body 17 to ensure airtightness inside the battery. The gasket 28 further insulates the outer casing 16 and the sealing body 17. The grooved portion 22 is a part of the side surface of the outer casing 16 that protrudes inward and supports the sealing body 17 via the gasket 28. The grooved portion 22 is formed in an annular shape along the circumferential direction of the outer casing 16 and supports the sealing body 17 on its upper surface. The sealing body 17 is fixed to the upper part of the outer casing 16 by the grooved portion 22 and the open end of the outer casing 16 which is crimped to the sealing body 17.

[0021] The grooved portion 22 is formed, for example, by spinning the side surface of the outer can 16 after housing the electrode body 14, the upper insulating plate 18, and the lower insulating plate 19 inside the outer can 16. The grooved portion 22 protrudes radially inward from the outer can 16 above the outer circumference of the electrode body 14 and faces the outer circumference of the electrode body 14 in the axial direction of the outer can 16. In this embodiment, since the outer can 16 functions as a negative electrode terminal, it is necessary to prevent electrical contact between the grooved portion 22 and the positive electrode 11 of the electrode body 14.

[0022] The sealing body 17 has a structure in which 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 in order from the electrode body 14 side. Each component constituting the sealing body 17 has, for example, a disc shape or a ring shape, and each component except 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, with the insulating member 25 interposed between their respective peripheries. When the internal pressure of the battery rises due to abnormal heat generation, the lower valve body 24 deforms and ruptures, pushing the upper valve body 26 towards the cap 27, thereby interrupting the current path between the lower valve body 24 and the upper valve body 26. If the internal pressure rises further, the upper valve body 26 ruptures, and gas is discharged from the opening of the cap 27.

[0023] The electrode body 14 has a hollow portion 14z extending in the axial direction of the electrode body 14 at and near the winding center. The hollow portion 14z serves as a gas discharge path when a malfunction occurs in the battery, and is also used as an insertion point for the welding rod when welding the negative electrode lead 21 to the inner surface of the bottom of the can. The upper insulating plate 18 has a through hole 32 formed at a position that overlaps the hollow portion 14z in the vertical direction so as not to obstruct the discharge of gas through the hollow portion 14z. The electrode body 14 is manufactured by winding the positive electrode 11 and the negative electrode 12 in a spiral shape with a separator 13 in between using a cylindrical winding core, and the hollow portion 14z is formed by removing the winding core after winding. It is also possible to leave the winding core in place. In either case, the hollow portion 14z is formed.

[0024] The configuration of the upper insulating plate 18 will be explained in detail below, with further reference to Figure 2. Figure 2 shows a plan view (a) and a cross-sectional view along line AA (b) of the upper insulating plate 18.

[0025] As shown in Figures 1 and 2, the upper insulating plate 18 is formed in a substantially disc shape and has an upper surface 18a (first surface) facing the sealing body 17 side and a lower surface 18b (second surface) facing the electrode body 14 side. The upper insulating plate 18 is a flat plate-like or sheet-like member with a constant thickness, and the upper surface 18a and the lower surface 18b are parallel. The upper insulating plate 18 broadly covers the upper surface of the electrode body 14 and prevents electrical contact between the negative electrode 12 and the positive electrode lead 20, and between the negative electrode 12 and the sealing body 17. In addition, the upper insulating plate 18 is interposed between the electrode body 14 and the grooved portion 22 of the outer can 16 and prevents electrical contact between the positive electrode 11 and the grooved portion 22.

[0026] The upper insulating plate 18 also functions as a fixing member that suppresses the movement of the electrode body 14. The diameter of the upper insulating plate 18 is smaller than the inner diameter of the portion located on the bottom side of the grooved portion 22 of the outer can 16, so that it can be easily inserted into the outer can 16. On the other hand, it is preferable that the diameter of the upper insulating plate 18 is larger than the inner diameter of the portion in which the grooved portion 22 is formed. In this case, the upper insulating plate 18 can easily catch on the grooved portion 22 and hold down the electrode body 14, thereby more effectively suppressing the movement of the electrode body 14 in the axial direction of the outer can 16.

[0027] The upper insulating plate 18 is preferably made of a hard material and has high rigidity. The upper insulating plate 18 may be made of a thermoplastic resin or a curable resin having a crosslinked structure. Examples of thermoplastic resins include polyolefins, polyamides, polyetheretherketones, and thermoplastic polyimides. Examples of curable resins include phenolic resins and epoxy resins. A suitable example of an upper insulating plate 18 is an insulating plate made of polypropylene. The upper insulating plate 18 may also contain reinforcing materials such as fibrous materials like glass fibers and carbon fibers, and fillers such as silica, clay, and mica.

[0028] The upper insulating plate 18 has a plurality of through holes 30, 31, and 32. The through holes 30, 31, and 32 are formed to penetrate the upper insulating plate 18 in the thickness direction. In a plan view of the upper insulating plate 18 from a direction perpendicular to the upper surface 18a, the through hole 32 is formed in the center of the upper insulating plate 18, and the through holes 30 and 31 are formed to surround the through hole 32. In plan view, the through hole 32 has a perfect circle shape, and the through holes 30 and 31 have a roughly arc shape. In the example shown in Figure 2, one through hole 30 and three through holes 31 smaller than the through hole 30 are arranged on the same circumference, but the number and arrangement of the through holes 30 and 31 are not particularly limited.

[0029] The through-holes 30, 31, and 32 serve as passages for gas when an abnormality occurs in the cylindrical battery 10. In addition, during the manufacturing process of the cylindrical battery 10, after the electrode body 14 and the upper insulating plate 18 are housed in the outer casing 16, the electrolyte is poured into the outer casing 16, so the through-holes 30, 31, and 32 serve as passages for the electrolyte. The through-hole 30 also functions as a lead insertion hole for passing the positive electrode lead 20 extending from the positive electrode 11 to the sealing body 17 side. Forming the through-holes 30, 31, and 32 reduces the insulating function of the upper insulating plate 18, but the through-holes 30, 31, and 32 need to be formed to a certain size.

[0030] As described above, the through-hole 32 is formed in a position that overlaps the hollow portion 14z in the vertical direction. That is, the negative electrode 12 of the electrode body 14 is not located below the through-hole 32. The through-hole 32 is also used as an insertion point for the welding rod when welding the negative electrode lead 21 to the inner surface of the bottom of the can. For this reason, it is preferable that the through-hole 32 penetrates the upper insulating plate 18 straight in the thickness direction. That is, it is preferable that the hole wall 37 of the through-hole 32 is parallel to the thickness direction of the upper insulating plate 18. Note that the form in which the hole wall is parallel to the thickness direction of the upper insulating plate 18 includes cases where it is considered substantially parallel, for example, when the inclination angle of the hole wall with respect to the thickness direction is less than 3°.

[0031] On the other hand, in the through holes 30 and 31, the respective hole walls 35 and 36 are inclined with respect to the thickness direction of the upper insulating plate 18 such that, in a plan view of the upper insulating plate 18, the area of ​​the second openings 30b and 31b on the lower surface 18b is smaller than the area of ​​the first openings 30a and 31a on the upper surface 18a. In this embodiment, the hole walls of all through holes except through hole 32 (hole wall 35 of through hole 30 and hole wall 36 of through hole 31) are inclined at a predetermined angle with respect to the thickness direction of the upper insulating plate 18. The inclination angles of the hole walls 35 and 36 may be the same or different.

[0032] As described above, the positive electrode lead 20 extends between the sealing body 17 and the upper insulating plate 18, along the upper surface 18a of the upper insulating plate 18, and is folded back at the bent portion 20a and connected to the sealing body 17. For this reason, for example, if the cylindrical battery 10 is subjected to a strong impact, there is a risk that the bent portion 20a may enter the through-hole from the sealing body 17 side and come into contact with the negative electrode 12 of the electrode body 14. With the cylindrical battery 10, by inclining the hole walls 35 and 36 of the through-holes 30 and 31, even if the bent portion 20a were to enter the through-holes 30 and 31 from the first openings 30 and 31a, it would hit the hole walls 35 and 36 and would not protrude from the second openings 30 and 31b. Therefore, contact between the positive electrode lead 20 and the negative electrode 12 can be prevented to a high degree.

[0033] In the through-hole 30, the first opening 30a and the second opening 30b have the same opening area. That is, the area of ​​the first opening 30a in a plan view of the upper insulating plate 18 is the same as the area of ​​the second opening 30b in a bottom view of the upper insulating plate 18. Similarly, in the through-hole 31, the first opening 31a and the second opening 31b have the same opening area. Note that the form in which the first and second opening areas are the same includes cases where the opening areas are considered to be substantially the same, for example, when the difference in opening areas is less than 3%.

[0034] One possible way to prevent contact between the positive lead 20 and the negative electrode 12 is to reduce the area of ​​the first or second opening. However, in this case, the function of the through-holes 30 and 31, which function as ventilation holes and liquid injection holes, will be reduced. By inclining the holes 35 and 36 of the through-holes 30 and 31 and making the areas of the first and second openings the same, contact between the positive lead 20 and the negative electrode 12 can be prevented without impairing the function of the through-holes 30 and 31.

[0035] The through holes 30 and 31 are elongated holes extending in the circumferential direction of the upper insulating plate 18. In this embodiment, of the hole walls 35 and 36 of the through holes 30 and 31, the hole walls along the longitudinal direction of the through holes 30 and 31 are inclined at predetermined angles θ1 and θ2 with respect to the thickness direction of the upper insulating plate 18. It is preferable that the pair of hole walls 35 extending along the longitudinal direction of the through hole 30 and facing each other in the width direction of the through hole 30 are formed parallel to each other. Similarly, it is preferable that the pair of hole walls 36 extending along the longitudinal direction of the through hole 31 and facing each other in the width direction of the through hole 31 are formed parallel to each other. Note that the form of being parallel to each other includes cases where they are considered substantially parallel.

[0036] The inclination angles θ1 and θ2 of the hole walls 35 and 36 of the through holes 30 and 31 in the upper insulating plate 18 with respect to the thickness direction are preferably 20° to 80°, more preferably 30° to 70°, or 45° to 65°. If the angles θ1 and θ2 are within this range, the effect of suppressing contact between the positive electrode lead 20 and the negative electrode 12 of the electrode body 14 becomes more pronounced. Angle θ1 refers to the angle between the hole wall 35 and a line parallel to the thickness direction of the upper insulating plate 18 that passes through the upper end of the hole wall 35, in a cross-section obtained by cutting the upper insulating plate 18 in the radial and thickness directions. Angle θ2 refers to the angle between the hole wall 36 and a line parallel to the thickness direction of the upper insulating plate 18 that passes through the upper end of the hole wall 36.

[0037] In this embodiment, the area of ​​the first opening 30a is larger than the area of ​​the first opening 31a, and the angle θ1 is larger than the angle θ2. Since the through hole 30 functions as a through hole for the positive electrode lead 20, it is preferable to make the opening area larger than that of the through hole 31. When there are two or more through holes with different opening areas, for example, the inclination angle of the hole wall is set to be larger for the through hole with a larger opening area than for the through hole with a smaller opening area. The angles θ1 and θ2 are constant from the first openings 30a and 31a to the second openings 30b and 31b, but they may change along the way, and the hole walls 35 and 36 may be gently curved.

[0038] Furthermore, the hole walls 35 and 36 of the through holes 30 and 31 are both inclined so that they gradually move towards the center of the upper insulating plate 18 from the first openings 30a and 31a towards the second openings 30b and 31b. As a result, the distance between the second openings 30b and 31b and the center of the upper insulating plate 18 is smaller than the distance between the first openings 30a and 31a and the center of the upper insulating plate 18. The hole walls 35 and 36 along the width direction of the through holes 30 and 31, that is, the hole walls 35 and 36 located at both ends in the length direction of the through holes 30 and 31, are parallel to the thickness direction of the upper insulating plate 18, similar to the hole wall 37 of the through hole 32. Alternatively, it is also possible to incline them at the same angle as the hole walls 35 and 36 along the length direction of the through holes 30 and 31.

[0039] The through holes 30 and 31 are formed so that, for example, the second openings 30b and 31b are not visible in a plan view of the upper insulating plate 18. In Figure 2, dot hatching is applied to the holes 35 and 36 of the through holes 30 and 31. In the example shown in Figure 2, the inside of the through holes 30 and 31 is visible from the first openings 30a and 31a, but the second openings 30b and 31b are not visible, and only the holes 35 and 36 are visible. That is, in a plan view of the upper insulating plate 18, the area of ​​the second openings 30b and 31b visible from the first openings 30a and 31a is zero. In this case, contact between the positive lead 20 and the negative lead 12 can be prevented more reliably. The inclination angles θ1 and θ2 of the holes 35 and 36 are set, for example, to angles such that the second openings 30b and 31b are not visible in a plan view of the upper insulating plate 18. Note that for the through hole 32, the second opening 32b is visible from the first opening 32a.

[0040] In a plan view of the upper insulating plate 18, the through-hole 30 is formed in half the area of ​​the upper surface 18a, and the through-hole 31 is formed in the remaining half of the area of ​​the upper surface 18a. The three through-holes 31 are formed, for example, so as to face the through-hole 30 in the radial direction of the upper insulating plate 18, and are also formed at equal intervals in the circumferential direction of the upper insulating plate 18. In Figure 2, the positive electrode lead 20 extending from the through-hole 30 is shown by a dashed line. The positive electrode lead 20 extends, for example, along the upper surface 18a, and the bent portion 20a is likely to be located above or near the through-hole 31. For this reason, inclining the hole wall 36 of the through-hole 31 is effective in suppressing contact between the positive electrode lead 20 and the negative electrode 12.

[0041] On the other hand, when the positive electrode lead 20 extends from one end of the through hole 30 in the longitudinal direction, the bent portion 20a may be located above or near the other end of the through hole 30 in the longitudinal direction. Since it is not easy to control the position of the bent portion 20a to a specific location above the upper surface 18a, inclining the hole wall 35 of the through hole 30 can more reliably prevent contact between the positive electrode lead 20 and the negative electrode 12.

[0042] As described above, the cylindrical battery 10 having the above configuration can more reliably prevent contact between the positive electrode lead 20 and the negative electrode 12 of the electrode body 14 without impairing the function of the through holes 30 and 31 in the upper insulating plate 18.

[0043] If the cylindrical battery 10 is subjected to a strong impact, there is a risk that a portion of the positive electrode lead 20 may enter the through-hole from the sealing body 17 side and come into contact with the negative electrode 12. However, this risk can be avoided by inclining the hole walls 35 and 36 of the through-holes 30 and 31 with respect to the thickness direction of the upper insulating plate 18. For example, even if the bent portion 20a of the positive electrode lead 20 enters the first opening 31a of the through-hole 31, the bent portion 20a will hit the inclined hole wall 36 and will not protrude toward the lower surface 18b. Therefore, with the cylindrical battery 10, even if an abnormality occurs such as the battery being subjected to a strong impact, contact between the positive electrode lead 20 and the negative electrode 12 can be prevented more reliably.

[0044] Furthermore, when the first opening 30a and the second opening 30b of the through-hole 30 have the same opening area, and when the first opening 31a and the second opening 31b of the through-hole 31 have the same opening area, the functions of the through-holes 30 and 31 as ventilation holes and electrolyte injection holes can be more effectively ensured. Furthermore, when the hole walls 35 and 36 of the through-holes 30 and 31 are inclined at an angle of 30° or more with respect to the thickness direction of the upper insulating plate 18, or are inclined such that the second openings 30b and 31b are not visible in a plan view of the upper insulating plate 18, or satisfy both of these conditions, the risk of contact between the positive electrode lead 20 and the negative electrode 12 can be more reliably avoided.

[0045] It should be noted that appropriate design changes can be made to the above embodiment without impairing the object of the present disclosure. FIG. 3 is a diagram showing a modification of the above embodiment.

[0046] As shown in FIG. 3, among the through-holes 30x and 31 arranged to surround the through-hole 32, the through-hole 30x through which the positive electrode lead 20 is inserted may be formed to straightly penetrate the upper insulating plate 18x in the thickness direction, similarly to the through-hole 32. In the upper insulating plate 18x shown in FIG. 3, among the plurality of through-holes 30x, 31, and 32, only the through-hole 31 is configured such that the area of the second opening 31b is smaller than the area of the first opening 31a in a plan view of the upper insulating plate 18x, more preferably, the hole wall 36 is inclined with respect to the thickness direction of the upper insulating plate 18x such that the second opening 31b becomes not visible in a plan view of the upper insulating plate 18x.

[0047] When the hole wall 35x of the through-hole 30x is parallel to the thickness direction of the upper insulating plate 18x, it becomes easy to pass the positive electrode lead 20 through the through-hole 30x, thereby improving the productivity of the cylindrical battery 10. Since the risk that a part of the positive electrode lead 20 enters the through-hole from the sealing body 17 side and contacts the negative electrode 12 is particularly high in the through-hole 31, according to the upper insulating plate 18x, the risk can be efficiently avoided while ensuring good productivity.

[0048] Furthermore, in the above embodiment, the positive electrode lead 20 is connected to the sealing body 17, and the sealing body 17 functions as a positive electrode terminal; however, the negative electrode lead 21 may be connected to the sealing body 17, and the sealing body 17 may function as a negative electrode terminal.

[0049] The present disclosure is further illustrated by the following embodiments. Configuration 1: A cylindrical battery comprising an electrode body, an electrolyte, a bottomed cylindrical outer container housing the electrode body and the electrolyte, a sealing body that closes the opening of the outer container, and an upper insulating plate disposed between the electrode body and the sealing body, wherein leads extending from a positive or negative electrode constituting the electrode body are connected to the sealing body, the upper insulating plate having a plurality of through holes penetrating from a first opening on a first surface facing the sealing body to a second opening on a second surface facing the electrode body, and at least one of the plurality of through holes having a hole wall inclined with respect to the thickness direction of the upper insulating plate such that, in a plan view of the upper insulating plate from a direction perpendicular to the first surface, the area of ​​the second opening is smaller than the area of ​​the first opening. Configuration 2: The cylindrical battery according to Configuration 1, wherein the first opening and the second opening have the same opening area in the plurality of through holes. Configuration 3: A cylindrical battery according to Configuration 1 or 2, wherein at least one of the plurality of through holes is formed so that the second opening is not visible in a plan view of the upper insulating plate. Configuration 4: A cylindrical battery according to any one of Configurations 1 to 3, wherein at least one of the plurality of through holes is an elongated hole extending in the circumferential direction of the upper insulating plate, and the hole wall along the length direction of the elongated hole is inclined at an angle of 30° or more with respect to the thickness direction of the upper insulating plate. Configuration 5: A cylindrical battery according to any one of Configurations 1 to 4, wherein the plurality of through holes include a first through hole through which the leads are inserted and a second through hole through which the leads are not inserted, and the hole wall of the second through hole is inclined with respect to the thickness direction of the upper insulating plate such that, in a plan view of the upper insulating plate, the area of ​​the second opening is smaller than the area of ​​the first opening. Configuration 6: The cylindrical battery according to Configuration 5, wherein, in a plan view of the upper insulating plate, the first through-hole is formed in half the area of ​​the first surface, and the second through-hole is formed in the remaining half area of ​​the first surface.

[0050] 10 Cylindrical battery, 11 Positive electrode, 12 Negative electrode, 13 Separator, 14 Electrode body, 14z Hollow section, 16 Outer casing, 17 Sealing body, 18, 18x Upper insulating plate, 18a Top surface, 18b Bottom surface, 19 Lower insulating plate, 20 Positive electrode lead, 20a Bent section, 21 Negative electrode lead, 22 Grooved section, 23 Internal terminal plate, 24 Lower valve body, 25 Insulating member, 26 Upper valve body, 27 Cap, 28 Gasket, 30, 30x, 31, 32 Through holes, 30a, 31a, 32a First opening, 30b, 31b, 32b Second opening, 35, 35x, 36 Hole wall

Claims

1. A cylindrical battery comprising an electrode body, an electrolyte, a bottomed cylindrical outer container housing the electrode body and the electrolyte, a sealing body that closes the opening of the outer container, and an upper insulating plate disposed between the electrode body and the sealing body, wherein leads extending from a positive or negative electrode constituting the electrode body are connected to the sealing body, the upper insulating plate having a plurality of through holes penetrating from a first opening on a first surface facing the sealing body to a second opening on a second surface facing the electrode body, and at least one of the plurality of through holes having a hole wall inclined with respect to the thickness direction of the upper insulating plate such that, in a plan view of the upper insulating plate viewed from a direction perpendicular to the first surface, the area of ​​the second opening is smaller than the area of ​​the first opening.

2. The cylindrical battery according to claim 1, wherein in the plurality of through holes, the first opening and the second opening have the same opening area.

3. The cylindrical battery according to claim 1 or 2, wherein at least one of the plurality of through holes is formed so that the second opening is not visible in a plan view of the upper insulating plate.

4. The cylindrical battery according to claim 1 or 2, wherein at least one of the plurality of through holes is an elongated hole extending in the circumferential direction of the upper insulating plate, and the hole wall along the longitudinal direction of the elongated hole is inclined at an angle of 30° or more with respect to the thickness direction of the upper insulating plate.

5. The cylindrical battery according to claim 1 or 2, wherein the plurality of through holes include a first through hole through which the lead is inserted and a second through hole through which the lead is not inserted, and the hole wall of the second through hole is inclined with respect to the thickness direction of the upper insulating plate such that, in a plan view of the upper insulating plate, the area of ​​the second opening is smaller than the area of ​​the first opening.

6. The cylindrical battery according to claim 5, wherein, in a plan view of the upper insulating plate, the first through hole is formed in half the area of ​​the first surface, and the second through hole is formed in the remaining half area of ​​the first surface.

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