Cylindrical battery

Abstract

The cylindrical battery disclosed herein comprises: a wound electrode body (14) formed by winding a positive electrode plate (11) and a negative electrode plate (12) with a spacer (13) between them, and having a cylindrical hollow portion (23) at the center of the winding; a cylindrical outer packaging can (16) for housing the electrode body (14); and a sealing body (17) for sealing the opening of the outer packaging can (16). The cylindrical battery includes leads (20) connected to the electrode plates constituting the electrode body (14), and has a current collector (30) connected to the leads (20) and the sealing body (17) and disposed between the electrode body (14) and the sealing body (17). The current collector (30) is characterized in that it is disposed such that the current collector (30) on the electrode body (14) side and the current collector (30) on the sealing body (17) side cover the hollow portion (23).

Description

Technical Field

[0001] This disclosure relates to a cylindrical battery, and more particularly to the internal structure of a cylindrical battery. Background Technology

[0002] Cylindrical batteries typically include: a wound electrode body, formed by spirally winding a positive electrode and a negative electrode with a spacer between them; a bottomed cylindrical outer packaging can that houses the electrode body; and a sealing body that seals the opening of the outer packaging can. The cylindrical battery has a structure in which leads extending from the electrode body are connected to the sealing body (see, for example, Patent Document 1). Additionally, a cylindrical hollow portion is formed in the center of the electrode body.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2005-285514 Summary of the Invention

[0006] When the electrode body overheats abnormally, the flame temperature and density are highest in the hollow section. Therefore, the seal at the top plate is directly impacted by the flame, causing it to melt and perforate, resulting in flames escaping from the hole. It should be noted that even the cylindrical battery described in existing literature 1 cannot solve this problem.

[0007] The disclosed cylindrical battery comprises: a wound electrode body formed by winding a positive electrode plate and a negative electrode plate with a spacer between them, and having a cylindrical hollow portion at the center of the winding; a cylindrical outer packaging can for housing the electrode body; and a sealing body for sealing the opening of the outer packaging can. The cylindrical battery includes leads connected to the electrode plates constituting the electrode body, and has a current collector connected to the leads and the sealing body and disposed between the electrode body and the sealing body. The current collector is characterized in that it is configured such that the current collector on the electrode body side and the current collector on the sealing body side cover the hollow portion.

[0008] According to the cylindrical battery disclosed herein, it is possible to suppress the direct impact of flame from the hollow part of the electrode body onto the sealing body when the battery is abnormally heated. Attached Figure Description

[0009] Figure 1 This is a cross-sectional view of the cylindrical battery of this embodiment.

[0010] Figure 2 This is a perspective view of the upper part of the cylindrical battery in this embodiment, showing the state before the sealing body is tightened and fixed. Detailed Implementation

[0011] Hereinafter, an example of an embodiment of the cylindrical battery of the present disclosure will be described in detail with reference to the accompanying drawings. It should be noted that the configuration formed by selectively combining the constituent elements of the various embodiments and modifications described below is included within the scope of the present disclosure.

[0012] Figure 1 This is a cross-sectional view of a cylindrical battery 10 as an example of an implementation. Figure 1 As shown, the cylindrical battery 10 includes: a wound electrode body 14, an electrolyte, a bottomed cylindrical outer packaging can 16 containing the electrode body 14 and the electrolyte, and a sealing body 17 that seals the opening of the outer packaging can 16. The electrode body 14 has a positive electrode 11, a negative electrode 12, and a spacer 13, and has a wound structure in which the positive electrode 11 and the negative electrode 12 are wound in a spiral shape, with the spacer 13 in between. Hereinafter, for ease of explanation, the sealing body 17 side of the battery will be shown as the upper side, and the bottom side of the outer packaging can 16 as the lower side.

[0013] The positive electrode 11, negative electrode 12, and spacer 13 constituting the electrode body 14 are all strip-shaped objects wound into a spiral shape, thereby being alternately stacked along the radial direction of the electrode body 14. To prevent lithium deposition, the negative electrode 12 is formed to be one size larger than the positive electrode 11. That is, the negative electrode 12 is formed to be longer in both the length and width directions than the positive electrode 11. The spacer 13 is formed to be at least one size larger than the positive electrode 11, for example, two pieces are arranged to clamp 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 (not shown) connected to the negative electrode 12 by welding or the like.

[0014] As detailed later, the cylindrical battery 10 includes multiple positive electrode leads 20. The cylindrical battery 10 further includes a current collector 30 disposed between the electrode body 14 and the sealing body 17. The current collector 30 is a conductive component that connects the positive electrode leads 20 and the sealing body 17, electrically connecting the positive electrode leads 20 and the sealing body 17. That is, in this embodiment, the current collector 30 functions as a positive electrode current collector. It should be noted that a negative electrode lead can also be connected to the current collector 30, thereby making the current collector 30 a negative electrode current collector.

[0015] The positive electrode 11 has a positive electrode core and a positive electrode binder layer disposed on the positive electrode core. The positive electrode core can be a foil of a metal that is stable in the potential range of the positive electrode 11, such as aluminum, aluminum alloy, stainless steel, or titanium, or a film of such metal disposed on its surface. The positive electrode binder layer contains a positive electrode active material, a conductive agent, and a binder, and is preferably disposed on both sides of the positive electrode core except for the portion connected to the positive electrode lead 20. 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 has a negative electrode core and a negative electrode binder layer disposed on the negative electrode core. The negative electrode core can be a foil of a metal 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 of such metal disposed on its surface. The negative electrode binder layer contains a negative electrode active material and a binder, and is preferably disposed on both sides of the negative electrode core except for the portion connected to the negative electrode lead. The negative electrode active material is usually a carbon material that can reversibly adsorb and release lithium ions. The negative electrode active material can also be an element that alloys with Li, such as Si or Sn, or a material containing such an element.

[0017] The spacer 13 uses a porous sheet with ion permeability and insulation. Specific examples of porous sheets include microporous films, woven fabrics, and nonwoven fabrics. The material of the spacer 13 is suitable as polyolefins such as polyethylene and polypropylene, cellulose, etc. The spacer 13 can be a single-layer structure or a multi-layer structure. For example, the spacer 13 can have a multi-layer structure including a thermoplastic resin layer such as a 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 electrolyte can be an aqueous electrolyte; however, a non-aqueous electrolyte is used in this embodiment. The non-aqueous electrolyte has lithium-ion conductivity. The non-aqueous electrolyte can be a liquid electrolyte (electrolyte) or a solid electrolyte.

[0019] Liquid electrolytes (electrolytes) comprise a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. Non-aqueous solvents include, for example, 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 contain halogen-substituted derivatives (e.g., fluoroethylene carbonate) in which at least a portion of the hydrogen atoms of these solvents are replaced by halogen atoms such as fluorine. Electrolyte salts include, for example, lithium salts such as LiPF6.

[0020] As a solid electrolyte, examples include solid or gel-like polymer electrolytes and inorganic solid electrolytes. As an inorganic solid electrolyte, materials known in all-solid-state lithium-ion secondary batteries (e.g., oxide-based solid electrolytes, sulfide-based solid electrolytes, halogen-based solid electrolytes, etc.) can be used. Polymer electrolytes may contain, for example, lithium salts and a matrix polymer, or a non-aqueous solvent, a lithium salt, and a matrix polymer. As a matrix polymer, for example, a polymer material that gels upon absorbing a non-aqueous solvent is used. Examples of polymer materials include fluoropolymers, acrylic resins, and polyether resins.

[0021] An insulating plate 18 is disposed on the upper surface of the electrode body 14. Figure 1 In the example shown, the positive lead 20 passes through the through hole in the insulating plate 18 and extends toward the sealing body 17. A current collector 30, connecting multiple positive leads 20, is connected to the lower surface of the sealing body 17 by welding or the like, thus the electrically connected sealing body 17 becomes the positive terminal. The negative lead is connected, for example, to the bottom inner surface of the outer packaging can 16 by welding or the like, thus the outer packaging can 16 becomes the negative terminal. The outer packaging can 16 and the sealing body 17 are connected, for example, to external circuitry such as other batteries or chargers that constitute the battery module.

[0022] The outer packaging can 16 is a bottomed cylindrical metal container with an axial opening on one side, and the opening of the outer packaging can 16 is sealed by a sealing body 17. A gasket 22 is provided between the outer packaging can 16 and the sealing body 17 to ensure the airtightness of the battery interior. A slotted portion 21 is formed on the outer packaging can 16, with a portion of its side protruding inward to support the sealing body 17. The slotted portion 21 is preferably formed in a ring shape along the circumference of the outer packaging can 16, and its upper surface supports the sealing body 17. The sealing body 17 is fixed to the upper part of the outer packaging can 16 by the slotted portion 21 and the opening end of the outer packaging can 16 that is cut and tightened to the sealing body 17.

[0023] The sealing body 17 seals the opening of the outer packaging can 16. Figure 1 In the example shown, the sealing body 17 is composed of a cover. The sealing body 17 may have a structure in which an internal terminal plate, a lower valve body, an insulating member, an upper valve body, and a cover are stacked sequentially from the electrode body 14 side. Each component constituting the sealing body 17 may be, for example, circular or annular, and the components, except for the insulating member, may be electrically connected to each other. In addition, the lower valve body and the upper valve body are connected at their respective central portions, and an insulating member may be sandwiched between their respective peripheral portions.

[0024] The following is a further reference Figure 2 At the same time, the positive lead 20 and the current collector 30 are described in detail. Figure 2 This is a perspective view of the upper part of the cylindrical battery 10, showing the state before the opening of the outer packaging can 16 is sealed by the sealing body 17.

[0025] like Figure 1 and Figure 2 As shown, the electrode body 14 includes multiple positive electrode leads 20 connected to the positive electrode 11. The multiple positive electrode leads 20 extend from the upper end of the electrode assembly 14a constituting the electrode body 14 towards the sealing body 17 and are connected to the current collector 30 disposed on the insulating plate 18. It should be noted that the electrode assembly 14a refers to a wound body composed of a positive electrode 11, a negative electrode 12, and a spacer 13, with a hollow portion 23 formed in the core of the electrode assembly 14a.

[0026] The hollow portion 23 is a space extending axially along the electrode assembly 14a. The current collector 30 is a conductive component connected to the sealing body 17, and the positive lead 20 is electrically connected to the sealing body 17 via the current collector 30. In this embodiment, since the outer packaging can 16 with the slotted portion 21 functions as the negative terminal, the current collector 30 is configured not to contact the slotted portion 21.

[0027] The positive electrode lead 20 is a strip-shaped conductive component, for example, made of a metal with aluminum as the main component. The preferred material for the positive electrode lead 20 is an aluminum alloy. An aluminum alloy is an alloy containing one or more other metallic elements such as copper, manganese, silicon, magnesium, zinc, and nickel. By adjusting the type and amount of added elements, the material's resistance, hardness, and other properties can be altered.

[0028] The width and thickness of the positive electrode lead 20 vary depending on the size and capacity of the battery. Examples of the width of the positive electrode lead 20 include 2mm or more and 15mm or less, or 3mm or more and 10mm or less. Examples of the thickness of the positive electrode lead 20 include 0.03mm or more and 0.15mm or less, or 0.05mm or more and 0.10mm or less. Multiple positive electrode leads 20 can have different widths and thicknesses; however, in… Figure 2 In the example shown, all the positive leads 20 have substantially the same width and thickness.

[0029] Positive lead 20 is soldered to the core of positive electrode 11. Multiple core exposed portions are provided along the length of positive electrode 11, where no positive electrode binder layer is present on the core; instead, the core exposed portions are exposed on the surface of the core. One positive lead 20 is connected to each exposed portion by soldering or the like. Normally, the positive lead 20 is only bonded to one side of the core; however, the core exposed portions are located on both sides of the positive electrode 11. The core exposed portions are formed, for example, of substantially the same size, thus coinciding in the thickness direction of the positive electrode 11. The soldering position of the positive lead 20 at each exposed portion is not particularly limited; the positive lead 20 is positioned within the range of the core exposed portions to avoid overlapping with the positive electrode binder layer.

[0030] exist Figure 2 In the illustrated embodiment, since three positive electrode leads 20 are provided, core exposed portions are formed at three points separated along the length direction of the positive electrode 11. The spacing between each exposed portion can be constant or different; for example, the layout of the positive electrode leads 20 can be appropriately set according to the battery performance such as the capacity and output characteristics of the cylindrical battery 10. Therefore, the spacing of each core exposed portion can be determined based on this layout, etc. It should be noted that the number of positive electrode leads 20 can be one, but in large batteries, multiple leads are preferred, for example, two or more and 15 or fewer.

[0031] The current collector 30 is a conductive component that welds multiple positive leads 20 to the sealing body 17. It is positioned between the electrode body 14 and the sealing body 17 and functions as a positive current collector. The material of the current collector 30 is not particularly limited; for example, it can be made of a metal with aluminum as the main component, similar to the positive leads 20. A suitable example of the material for the current collector 30 is an aluminum alloy. A welding portion 32 is formed between the current collector 30 and the sealing body 17, and a welding portion 31 is formed between the current collector 30 and the positive leads 20.

[0032] The current collector 30 is disposed on the electrode body 14 with an insulating plate 18 in between. Although the current collector 30 is disposed on the insulating plate 18, it can also be fixed to the insulating plate 18. It should be noted that the insulating material sandwiched between the electrode body 14 and the current collector 30 is not limited to the insulating plate 18; for example, it can be any insulating material constituting the electrode body 14 or the current collector 30. Examples of insulating materials other than the insulating plate 18 include the spacer 13 constituting the electrode body 14 and the insulating layer provided on the surface of the current collector 30 facing the electrode body 14.

[0033] like Figure 1 As shown, the current collector 30 is configured such that the current collector 30 on the electrode body 14 side and the current collector 30 on the sealing body 17 side cover the hollow portion 23 of the electrode body 14. The current collector 30 has a width and length larger than the diameter of the hollow portion 23, and is configured, for example, to cover the entire hollow portion 23 and the radially inner portion of the electrode body 14.

[0034] The current collector 30 may have a through hole 34 in the portion covering the hollow portion 23. The hollow portion 23 of the electrode body 14 serves as an exhaust passage when gas is generated due to a battery malfunction. Furthermore, by providing the through hole 34 to the current collector 30, the flame generated in the hollow portion 23 can be dispersed between the current collector 30 on the sealing body 17 side and the current collector 30 on the electrode body 14 side. This reduces the flame density emitted from the hollow portion 23, thereby suppressing battery explosion.

[0035] The current collector 30 is configured such that at least a portion of the through hole 34 overlaps with the hollow portion 23 in the axial direction of the electrode body 14. Figure 2 In the example shown, the positive lead 20 is soldered around the through hole 34 of the current collector 30 without covering the through hole 34.

[0036] Multiple welded portions 31 are formed in the current collector 30 surrounding the through hole 34. The positive lead 20 is welded to the first surface (upper surface) of the current collector 30 in the direction of the sealing body 17, or to the second surface (lower surface) of the current collector 30 in the direction of the electrode body 14, or to both the first and second surfaces. Figure 2In the example shown, all the positive leads 20 are welded to the upper surface of the current collector 30. In this case, a good weld 31 can be easily formed, and the reliability of the weld 31 is improved. The weld 31 can also be formed on the hollow portion 23 of the electrode body 14. In this case, the weld 31 can be formed by inserting a jig used during welding into the hollow portion 23.

[0037] A through hole 34 is formed along the axial direction of the electrode body 14, penetrating the current collector 30. Figure 2 The example shown has a shape that is perfectly circular when viewed from above. Additionally, a through hole is formed on the insulating plate 18 at a position overlapping with the through hole 34. When viewed from above, the through hole 34 can be larger than the hollow portion 23, allowing the entire hollow portion 23 to be exposed through the through hole 34, thus positioning the current collector 30 on the electrode body 14. For example, the current collector 30 is configured such that the center of the through hole 34 coincides with the central axis of the electrode body 14.

[0038] As shown above, in the illustrated embodiment, the current collector 30 on the electrode body 14 side has a through hole 34 at a position covering the hollow portion 23 of the electrode body 14. However, in this disclosure, a structure without the through hole 34 can also be adopted. That is, the flame generated in the hollow portion 23 of the electrode body 14 can be doubly suppressed by the current collector 30 located on both the electrode body 14 side and the sealing body 17 side of the current collector 30.

[0039] The current collector 30 has a folded-back portion 33 near the middle portion of the current collector 30 on the electrode body 14 side and the current collector 30 on the sealing body 17 side. The folded-back portion 33 is formed by bending the metal plate constituting the current collector 30. In addition, the folded-back portion 33 is formed parallel to the width direction of the current collector 30. It should be noted that a semi-tangent, a groove, etc., can be formed in the folded-back portion 33. At least one folded-back portion 33 is formed, but multiple folded-back portions can also be formed in the length direction of the current collector 30.

[0040] The current collector 30 is preferably wider and thicker than the positive lead 20. The current collector 30 is, for example, a metal plate with a substantially constant width and thickness over its entire length. The dimensions of the current collector 30 can be appropriately varied depending on the size of the cylindrical battery 10, for example, the width of the current collector 30 is 10 mm or more and 30 mm or less, or 15 mm or more and 25 mm or less. The thickness of the current collector 30 is, for example, 0.1 mm or more and 1.0 mm or less, or 0.2 mm or more and 0.5 mm or less.

[0041] The width of the current collector 30 is greater than its thickness. The ratio of the width to the thickness of the current collector 30 is preferably 30 times or more and 100 times or less, more preferably 40 times or more and 90 times or less, and particularly preferably 50 times or more and 80 times or less. It should be noted that even if at least one of the thickness and width of the current collector 30 is not constant, it is acceptable as long as the ratio of the average width to the average thickness, or the ratio of the maximum width to the maximum thickness, is within this range.

[0042] The cross-sectional area in the width direction of the current collector 30 is larger than that of the positive lead 20, preferably 5 times or more but less than 100 times. More preferably, it is 10 times or more but less than 50 times, and particularly preferably 15 times or more but less than 30 times. In this case, contact between the outer packaging can 16 and the current collector 30 can be suppressed. Even if the cross-sectional area in the width direction of at least one of the positive lead 20 and the current collector 30 is not constant, it is acceptable as long as the ratio of the average value or the ratio of the maximum value of the cross-sectional areas in the width direction of each component is within this range. The cross-sectional area in the width direction of the current collector 30 is preferably increased by making both its thickness and width larger than that of the positive lead 20.

[0043] The thickness of the current collector 30 is, for example, 1.5 times or more and 15 times or less, preferably 2 times or more and 10 times or less, the thickness of the positive lead 20. Even if at least one of the thicknesses of the positive lead 20 and the current collector 30 is not constant, it is acceptable as long as the ratio of the average thickness of each component to its maximum thickness is within this range (the same applies to the width). Furthermore, the width of the current collector 30 is, for example, 1.5 times or more and 10 times or less, preferably 2 times or more and 6 times or less, the width of the positive lead 20.

[0044] The maximum width of the current collector 30 is preferably 30% to 90% of the minimum inner diameter of the outer packaging can 16, more preferably 35% to 80%, and particularly preferably 40% to 70%. In this embodiment, the inner diameter of the outer packaging can 16 is smallest at the portion where the slot 21 is formed. If the ratio of the maximum width of the current collector 30 to the minimum inner diameter of the outer packaging can 16 is within this range, contact between the outer packaging can 16 and the current collector 30 can be suppressed, and the soldering of the positive lead 20 becomes easier.

[0045] The current collector 30 is configured such that a portion forming the weld portion 31 with the positive lead 20 (hereinafter referred to as "first region") is located on the insulating plate 18 along the radial direction of the electrode body 14. Additionally, the current collector 30 is configured such that a portion forming the weld portion 32 with the sealing body 17 (hereinafter referred to as "second region") is located along the lower surface of the sealing body 17. At least one weld portion 32 is formed in the second region. In this embodiment, the fold-back portion 33 forms the boundary between the first region and the second region. The fold-back portion 33 is located radially outward from the longitudinal end of the current collector 30 present in the first region, and is close to the slotted portion 21. It should be noted that in this embodiment, since the outer packaging can 16 with the slotted portion 21 functions as the negative terminal, the current collector 30 is configured not to contact the slotted portion 21.

[0046] The width of the current collector 30 can vary along its length. In order to increase the width of the current collector 30 while preventing it from contacting the outer packaging can 16, the width of the current collector 30 can be varied, reducing the width of the portion where the fold-back portion 33 is formed relative to the end in the length direction. That is, regarding the width of the current collector 30, the portion where the fold-back portion 33 is formed can be smaller than the end in the length direction on the electrode body 14 side.

[0047] The width of the first region of the current collector 30 may gradually narrow from one end along the length direction toward the return portion 33, or it may narrow in a stepped manner at more than one point. The width of the return portion 33 of the current collector 30 may be, for example, less than 90% of the width of one end along the length direction, or it may be more than 30% and less than 80%, or more than 50% and less than 70%. The width of the second region of the current collector 30 may be substantially the same as the width of the return portion 33 over its entire length, or it may be wider than the return portion 33.

[0048] The current collector 30 is bent into an L-shape at the fold-back portion 33, and has an L-shape when no external force is applied. By chiseling and securing the sealing body 17 at the opening edge of the outer packaging can 16, the current collector 30 is bent at the fold-back 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 of axial compression along the electrode body 14. The first region and the second region of the current collector 30 are arranged substantially parallel, for example, and can face each other with a small gap, and the positive lead 20 soldered to the upper surface of the first region can be clamped therebetween.

[0049] As shown above, in the cylindrical battery with the above configuration, since the current collector 30 on the electrode body 14 side and the current collector 30 on the sealing body 17 side are configured to cover the hollow portion 23 of the electrode body 14, two facing current collectors 30 are disposed on the hollow portion 23. This suppresses the possibility of flames generated in the hollow portion 23 directly impacting the sealing body 17. Consequently, it prevents flames from escaping from the sealing body 17 if a hole is formed in it.

[0050] It should be noted that the above embodiments can be appropriately modified without prejudice to the purpose of this disclosure, and can also be constructed by selectively combining the constituent elements of the above embodiments. For example, in Figure 2 In the illustrated embodiment, the number of positive leads 20 can also be set to 6. Alternatively, multiple current collectors 30 can be arranged between the electrode body 14 and the sealing body 17.

[0051] Explanation of reference numerals in the attached figures

[0052] 10 Cylindrical battery, 11 Positive electrode, 12 Negative electrode, 13 Spacer, 14 Electrode body, 14a Electrode assembly, 16 Outer packaging can, 17 Sealing body, 18 Insulating board, 20 Positive lead, 21 Slotted part, 22 Gasket, 23 Hollow part, 30 Current collector, 31, 32 Welded parts, 33 Fold-back part, 34 Through hole.

Claims

1. A cylindrical battery, comprising: A wound electrode body is formed by winding a positive electrode plate and a negative electrode plate with a spacer in between, and has a cylindrical hollow part at the center of the winding. A cylindrical outer packaging can houses the electrode body; and A sealing element to seal the opening of the outer packaging can. The cylindrical battery includes leads connected to the electrode plates constituting the electrode body. The cylindrical battery includes a current-collecting member connected to the leads and the sealing body, and disposed between the electrode body and the sealing body. The current collector is configured such that the current collector on the electrode body side and the current collector on the sealing body side cover the hollow portion.

2. The cylindrical battery according to claim 1, wherein, The current collector has a folded-back portion at the midpoint between the current collector on the electrode body side and the current collector on the sealing body side. The current collector on the electrode body side is connected to the lead wire. The current collector on the sealing body side is connected to the sealing body.

3. The cylindrical battery according to claim 1 or 2, wherein, The current collector on the electrode body side has a through hole at the position covering the hollow portion.

Images