JP7320166B2 - secondary battery - Google Patents

Description

TECHNICAL FIELD The present disclosure relates to a secondary battery, and more particularly to a secondary battery having an insulating tape attached to electrodes.

Conventionally, in a secondary battery having a wound electrode body, a structure is known in which an electrode constituting the electrode body is provided with an exposed portion where the surface of the core body is exposed, and a current collecting lead is connected to the exposed portion. ing. The surface of the lead and the exposed part is a part where the surface of the low-resistance metal is exposed without the mixture layer, so if an internal short circuit occurs here, a large current will flow through the short circuit and the heat value of the battery will increase. become more. Therefore, an insulating tape is attached so as to cover the leads and exposed portions to prevent the occurrence of such a low-resistance short circuit (see, for example, Patent Document 1).

JP 2008-234855 A

By the way, secondary batteries are required to have high safety performance that does not cause an internal short circuit that causes fire even when a strong impact force that deforms the battery is applied from the outside. As described above, the insulating tape covering the lead and the exposed portion prevents the occurrence of a low-resistance short circuit, but since the lead and the insulating tape have a certain thickness, a step is formed on the electrode surface due to their thickness. be done. Then, when a strong impact force that deforms the battery is applied from the outside, the separator may break at the portion where the step exists, causing a short circuit.

An object of the present disclosure is to provide a secondary battery that can prevent the occurrence of an internal short circuit even when a strong impact force that deforms the battery is applied from the outside.

A secondary battery according to one embodiment of the present disclosure is a secondary battery including an electrode body in which a positive electrode and a negative electrode are wound with a separator interposed therebetween, wherein the positive electrode and the negative electrode are formed on a core and on the surface of the core. At least one of the positive electrode and the negative electrode includes a lead connected to an exposed portion where the surface of the core body is exposed, and an insulating tape covering the lead and the exposed portion. be provided. The insulating tape includes a base material and an adhesive layer provided on one surface of the base material, and on one surface of the base material, the adhesive layers are provided on both sides in the width direction of the base material, A region in which the adhesive layer does not exist is formed with a width equal to or greater than the width of the lead in the widthwise central portion of the base material that overlaps with the lead.

According to the secondary battery of one aspect of the present disclosure, it is possible to prevent an internal short circuit from occurring even when a strong impact force that deforms the battery is applied from the outside.

1 is a cross-sectional view of a non-aqueous electrolyte secondary battery that is an example of an embodiment; FIG. It is a figure which shows a part of positive electrode which is an example of embodiment. It is a figure which shows the insulating tape which is an example of embodiment. It is a figure which shows a part of AA line cross section in FIG.

As described above, preventing internal short circuits in secondary batteries is an important issue. The present inventors have found that by using an insulating tape having a region where no adhesive layer exists (lead width ≤ width of the region) in the center of the width direction of the tape that overlaps the lead, a strong impact force that deforms the battery can be obtained. It was found that the occurrence of an internal short circuit is highly suppressed even when a is applied from the outside. Since the thickness of the insulating tape is thin at the portion overlapping the lead, it is possible to reduce the step formed on the surface of the positive electrode due to the thickness of the lead and the insulating tape. It is considered that the use of this insulating tape alleviates the influence of the step, and prevents the separator from breaking at the portion where the step is formed to cause a short circuit.

An example of an embodiment of the present disclosure will be described in detail below. Since the drawings referred to in the description of the embodiments are schematically illustrated, the dimensional ratios and the like of each component should be determined with reference to the following description.

In this embodiment, a secondary battery in which a wound electrode body is housed in a bottomed cylindrical outer can is exemplified. It may also be an exterior body composed of a laminate sheet including a metal layer and a resin layer. Further, a structure in which the core exposing portion of the negative electrode formed on the outer peripheral surface of the electrode body is in contact with the inner surface of the outer can and the negative electrode and the outer can are electrically connected is exemplified. The inner surface of the can may not be electrically connected.

FIG. 1 is a cross-sectional view of a secondary battery 10 that is an example of an embodiment. As illustrated in FIG. 1, the secondary battery 10 includes an electrode body 14, an electrolyte (not shown), and an outer can 16 that accommodates the electrode body 14 and the electrolyte. The electrode body 14 has 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. The outer can 16 is a bottomed cylindrical metal container that is open on one side in the axial direction. Hereinafter, for convenience of explanation, the sealing body 17 side of the secondary battery 10 is referred to as the upper side, and the bottom side of the outer can 16 is referred to as the lower side.

A non-aqueous electrolyte, for example, is used as the electrolyte. The non-aqueous electrolyte 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 thereof. The non-aqueous solvent may contain a halogen-substituted product obtained by substituting at least part of the hydrogen atoms of these solvents with halogen atoms such as fluorine. Note that the non-aqueous electrolyte is not limited to a liquid electrolyte, and may be a solid electrolyte. A lithium salt such as LiPF ₆ is used as the electrolyte salt. The type of electrolyte is not particularly limited, and may be an aqueous electrolyte.

The positive electrode 11, the negative electrode 12, and the separator 13, which constitute the electrode assembly 14, are all strip-shaped elongated bodies, and are alternately laminated in the radial direction of the electrode assembly 14 by being spirally wound. The positive electrode 11 has a positive electrode core 30 and a positive electrode mixture layer 31 provided on the surface of the positive electrode core 30 . Similarly, the negative electrode 12 has a negative electrode core 40 and a negative electrode mixture layer 41 provided on the surface of the negative electrode core 40 . The secondary battery 10 includes insulating plates 18 and 19 arranged above and below the electrode assembly 14, respectively.

The negative electrode 12 is arranged on the outer peripheral surface of the electrode body 14, and an exposed portion 42 where the surface of the negative electrode core 40 is exposed is formed. The exposed portion 42 may be formed on a part of the outer peripheral surface of the electrode body 14, but is preferably formed on the entire outer peripheral surface. The exposed portion 42 may be formed only on one surface (outer surface) of the negative electrode core 40 facing the outside of the electrode body 14 , or may be formed on both surfaces of the negative electrode core 40 . The exposed portion 42 is formed, for example, in a range of length from one longitudinal end of the negative electrode core 40 located on the outer peripheral surface of the electrode assembly 14 to about one to two circumferences of the electrode assembly 14 .

In the secondary battery 10 , the exposed portion 42 of the negative electrode 12 is in contact with the inner surface of the outer can 16 so that the negative electrode 12 and the outer can 16 are electrically connected. In this embodiment, the sealing member 17 serves as a positive electrode external terminal, and the outer can 16 serves as a negative electrode external terminal. A positive electrode lead 20 attached to the positive electrode 11 extends through the through hole of the insulating plate 18 toward the sealing member 17 and is connected to the bottom surface of the inner terminal plate 23, which is the bottom plate of the sealing member 17, by welding or the like. A negative electrode lead may not be connected to the negative electrode 12. An exposed portion is formed at the other longitudinal end of the negative electrode 12 located on the core side of the electrode body 14, and the inner surface of the bottom of the outer can 16 is welded or the like. may be attached to the exposed portion.

A gasket 28 is provided between the outer can 16 and the sealing member 17 to ensure hermeticity inside the battery. The outer can 16 is formed with a grooved portion 21 that supports the sealing member 17 and has a portion of the side surface projecting inward. The grooved portion 21 is preferably annularly formed along the circumferential direction of the outer can 16 and supports the sealing body 17 on the upper surface thereof. The sealing member 17 is fixed to the upper portion of the outer can 16 by the grooved part 21 and the open end of the outer can 16 crimped to the sealing member 17 .

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 layered in order from the electrode body 14 side. Each member constituting the sealing member 17 has, for example, a disk shape or a ring shape, and each member other than the insulating member 25 is electrically connected to each other. The lower valve body 24 and the upper valve body 26 are connected to each other at their central portions, and an insulating member 25 is interposed between their peripheral edge portions. When the internal pressure of the battery rises due to abnormal heat generation, the lower valve body 24 is deformed to push up the upper valve body 26 toward the cap 27 and breaks, cutting off the current path between the lower valve body 24 and the upper valve body 26 . be. When the internal pressure further increases, the upper valve body 26 is broken and the gas is discharged from the vent hole of the cap 27 .

2 to 4, the positive electrode 11, negative electrode 12, and separator 13 constituting the electrode body 14, particularly the positive electrode 11 and the insulating tape 50 attached to the positive electrode 11, will be described in detail. 2 is a front view of the positive electrode 11, and FIG. 4 is a view showing a part of the AA line cross section in FIG. 3A and 3B are a plan view and a rear view of the insulating tape 50. FIG.

[Positive electrode]
As described above, the positive electrode 11 has the positive electrode core 30 and the positive electrode mixture layer 31 provided on the surface of the positive electrode core 30 . For the positive electrode core 30, a foil of a metal such as aluminum that is stable in the potential range of the positive electrode 11, a film having the metal on the surface layer, or the like can be used. The positive electrode mixture layer 31 contains a positive electrode active material, a conductive agent, and a binder, and is preferably provided on both surfaces of the positive electrode core 30 excluding the exposed portion 32 to which the positive electrode lead 20 is connected. The thickness of the positive electrode mixture layer 31 on one side of the positive electrode core 30 is, for example, 50 μm to 150 μm. The positive electrode 11 is formed by applying, for example, a positive electrode mixture slurry containing a positive electrode active material, a conductive agent, a binder, etc. to the surface of the positive electrode core 30 , drying the coating film, and then compressing the positive electrode mixture layer 31 . can be formed on both sides of the positive electrode core 30 .

The positive electrode active material is mainly composed of a lithium-containing transition metal composite oxide. Metal elements contained in the lithium-containing transition metal composite oxide include Ni, Co, Mn, Al, B, Mg, Ti, V, Cr, Fe, Cu, Zn, Ga, Sr, Zr, Nb, In, Sn, Ta, W etc. are mentioned. An example of a suitable lithium-containing transition metal composite oxide is a composite oxide containing at least one of Ni, Co, and Mn. Specific examples include lithium-containing transition metal composite oxides containing Ni, Co, and Mn, and lithium-containing transition metal composite oxides containing Ni, Co, and Al.

Examples of the conductive agent contained in the positive electrode mixture layer 31 include carbon materials such as carbon black, acetylene black, ketjen black, and graphite. Examples of the binder contained in the positive electrode mixture layer 31 include fluororesins such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), polyimide resins, acrylic resins, and polyolefin resins. can. These resins may be used in combination with cellulose derivatives such as carboxymethyl cellulose (CMC) or salts thereof, polyethylene oxide (PEO), and the like.

As illustrated in FIG. 2, the positive electrode 11 is provided with a positive electrode lead 20 connected to the exposed portion 32 where the surface of the positive electrode core 30 is exposed, and an insulating tape 50 covering the positive electrode lead 20 and the exposed portion 32. ing. The exposed portions 32 are portions where the surface of the positive electrode core 30 is exposed without being covered with the positive electrode mixture layer 31 , and are formed on both surfaces of the positive electrode 11 so as to overlap in the thickness direction of the positive electrode 11 . In this embodiment, the exposed portion 32 is formed in the central portion of the positive electrode 11 in the longitudinal direction, and the positive electrode lead 20 and the insulating tape 50 are arranged in the central portion of the positive electrode 11 in the longitudinal direction. In addition, the exposed portion 32 is formed with a width wider than the width W of the positive electrode lead 20 over the entire width direction of the positive electrode 11 . The exposed portion 32 has a rectangular shape elongated in the lateral direction of the positive electrode 11 when viewed from the front.

The positive electrode lead 20 is generally a strip-shaped conductive member that is thicker than the positive electrode core 30 and the positive electrode mixture layer 31 . The positive lead 20 has a thickness of, for example, 50 μm to 500 μm and a width W of 3 mm to 4 mm. Although the constituent material of the positive electrode lead 20 is not particularly limited, it is preferably made of a metal containing aluminum as a main component. The positive electrode lead 20 is connected to one of two exposed portions 32 formed on both surfaces of the positive electrode 11 by welding or the like. A portion of the positive electrode lead 20 extends from the upper end of the positive electrode core 30 and is connected to the inner terminal plate 23 of the sealing member 17 .

The insulating tape 50 is provided on one surface of the positive electrode 11 (hereinafter referred to as “first surface”) to which the positive electrode lead 20 is attached, and on the other surface of the positive electrode 11 (hereinafter referred to as “second surface”). It is also preferable that the tape is attached so as to cover the exposed portion 32 . That is, both of the two exposed portions 32 formed on the positive electrode 11 are covered with the insulating tape 50 . The two insulating tapes 50 may be joined together. As the insulating tape attached to the second surface of the positive electrode 11, a conventionally known tape may be used.

The insulating tape 50 has a rectangular shape (strip shape) wider than the positive electrode lead 20 and the exposed portion 32 when viewed from the front. The insulating tape 50 is preferably attached to the first surface of the positive electrode 11 while covering the entire portion of the positive electrode lead 20 located on the exposed portion 32 . Also, the insulating tape 50 is attached to the first surface and the second surface of the positive electrode 11 so as to cover the entire two exposed portions 32, for example. The insulating tape 50 is adhered so that its longitudinal direction is along the lateral direction of the positive electrode 11 and its width direction is along the longitudinal direction of the positive electrode 11 .

The insulating tape 50 is preferably adhered over the extending portion of the positive electrode lead 20 extending from the upper end of the positive electrode core 30 . Since a part of the extended portion of the positive electrode lead 20 faces the negative electrode 12 with the separator 13 interposed therebetween, there is concern that a low-resistance short circuit may occur when the separator 13 is damaged. Therefore, the insulating tape 50 is adhered to this portion as well. Moreover, the insulating tape 50 has dimensions larger than the exposed portion 32 so as to reliably cover the entire exposed portion 32 , and is part of the positive electrode mixture layer 31 formed on both sides of the exposed portion 32 . , and is stuck on both sides of the positive electrode 11 in the short direction.

As illustrated in FIGS. 3 and 4, the insulating tape 50 has a base material 51 and an adhesive layer 52 provided on one surface (hereinafter referred to as "back surface") of the base material 51. As shown in FIGS. Although the thickness of the insulating tape 50 is not particularly limited, it is 20 μm to 70 μm as an example. The thickness of the base material 51 is generally thicker than that of the adhesive layer 52, and is, for example, 10 μm to 45 μm. The thickness of the adhesive layer 52 is, for example, 5 μm to 30 μm. The base material 51 may be provided with layers other than the adhesive layer 52 as long as the object of the present disclosure is not impaired.

The base material 51 is mainly composed of a resin having insulating properties, electrolyte resistance, and the like. Suitable resins constituting the base material 51 include polyester such as polyethylene terephthalate (PET), polyolefin such as polypropylene (PP), polyimide (PI), polyphenylene sulfide, polyamide, and polyamideimide. Among them, polyimide having high mechanical strength (puncture strength) is particularly preferable. A resin film made of polyimide, for example, can be used as the base material 51 . The base material 51 may contain fillers such as alumina and titania.

The adhesive layer 52 is a layer for imparting adhesiveness to the positive electrode 11 to the tape. The adhesive layer 52 is formed, for example, by applying an adhesive to the back surface of the base material 51 . The adhesive layer 52 is preferably configured using an adhesive having excellent insulating properties, electrolyte resistance, and the like. The adhesive that constitutes the adhesive layer 52 may be of the hot-melt type or the thermosetting type, but from the viewpoint of productivity and the like, it is preferable that the adhesive be tacky at room temperature. Examples of adhesives forming the adhesive layer 52 are acrylic adhesives and synthetic rubber adhesives.

The insulating tape 50 is adhered to the surface of the positive electrode mixture layer 31 formed on both sides of the exposed portion 32 with an adhesive layer 52 . On the back surface of the base material 51 , the adhesive layers 52 are provided on both sides in the width direction of the base material 51 . It is formed with a width W2 that is greater than or equal to the width W. The insulating tape 50 is adhered to the first surface of the positive electrode 11 with the region 53 overlapping the positive electrode lead 20 and in contact with the surface of the positive electrode lead 20 . That is, the insulating tape 50 is not attached to the positive electrode lead 20 . Note that the insulating tape 50 may be adhered to the exposed portion 32 .

Since the insulating tape 50 does not have the adhesive layer 52 in the central portion in the width direction overlapping the positive electrode lead 20 , the thickness in the central portion in the width direction is thin. A step formed on the first surface of 11 can be reduced. That is, the use of the insulating tape 50 alleviates the step. Therefore, even if a strong impact force is applied from the outside of the battery, it is possible to prevent the breakage of the separator 13 at the stepped portion and the occurrence of a short circuit.

In the insulating tape 50, the adhesive layers 52 are provided only on both sides in the width direction of the base material 51, as described above. For this reason, a groove-like concave portion sandwiched by the adhesive layers 52 is formed in the widthwise central portion of the insulating tape 50 where the region 53 where the adhesive layer 52 is not provided exists. The adhesive layer 52 is provided with the same width from both ends of the substrate 51 in the width direction, for example, over the entire length of the substrate 51 in the longitudinal direction. In this case, the groove-shaped concave portion is formed with a constant width over the entire length of the insulating tape 50 .

The width W1 of the insulating tape 50 is, for example, two to three times the width W of the positive electrode lead 20, and is, for example, 5 mm to 10 mm. The width W2 of the region 53 (groove-shaped recess) is 1 or more times the width W of the positive electrode lead 20, preferably 1.05 to 1.50 times, more preferably 1.10 to 1.20 times. is. In this case, the insulating tape 50 can be arranged so that the adhesive layer 52 does not overlap the positive electrode lead 20 while ensuring good adhesion of the insulating tape 50 to the positive electrode 11 . The insulating tape 50 is adhered so that the positive electrode lead 20 fits into the recess.

[Negative electrode]
As described above, the negative electrode 12 has the negative electrode core 40 and the negative electrode mixture layer 41 provided on the surface of the negative electrode core 40 . The negative electrode 12 has an exposed portion 42 where the surface of the negative electrode core 40 is exposed at a portion corresponding to the outer peripheral surface of the electrode body 14 . For the negative electrode core 40, a foil of a metal such as copper that is stable in the potential range of the negative electrode 12, a film having the metal on the surface layer, or the like can be used. The negative electrode mixture layer 41 contains a negative electrode active material and a binder, and is preferably provided on both surfaces of the negative electrode core 40 excluding the portion where the negative electrode lead is connected and the exposed portion 42 , for example. The thickness of the negative electrode mixture layer 41 on one side of the negative electrode core 40 is, for example, 50 μm to 150 μm. For the negative electrode 12, for example, a negative electrode mixture slurry containing a negative electrode active material, a binder, and the like is applied to the surface of the negative electrode core 40, the coating film is dried, and then compressed to form the negative electrode mixture layer 41 on the surface of the negative electrode core. It can be made by forming on both sides of the body 40 .

The negative electrode mixture layer 41 contains, as a negative electrode active material, for example, a carbon-based active material that reversibly absorbs and releases lithium ions. Suitable carbon-based active materials are graphite such as natural graphite such as flake graphite, massive graphite and earthy graphite, artificial graphite such as massive artificial graphite (MAG) and graphitized mesophase carbon microbeads (MCMB). In addition, a Si-based active material composed of at least one of Si and a Si-containing compound may be used as the negative electrode active material, or a carbon-based active material and a Si-based active material may be used in combination.

As the binder contained in the negative electrode mixture layer 41, as in the case of the positive electrode 11, fluorine resin, PAN, polyimide resin, acrylic resin, polyolefin resin, or the like can be used. is preferably used. Moreover, the negative electrode mixture layer 41 preferably further contains CMC or a salt thereof, polyacrylic acid (PAA) or a salt thereof, polyvinyl alcohol (PVA), or the like. Among them, it is preferable to use SBR together with CMC or a salt thereof and PAA or a salt thereof.

An insulating tape 50 covering the leads may be provided on the positive electrode 11 and the negative electrode 12 or only on the negative electrode 12 . When the negative electrode lead is provided, a region 53 where the adhesive layer 52 does not exist is formed with a width equal to or greater than the width of the negative electrode lead in the center portion in the width direction of the base material 51 overlapping the negative electrode lead. A portion of the insulating tape 50 where the region 53 is formed becomes a groove-like recess sandwiched between the adhesive layers 52 . The insulating tape 50 is adhered so that the negative electrode lead fits into the recess.

[Separator]
A porous sheet having ion permeability and insulation is used for the separator 13 . Specific examples of porous sheets include microporous thin films, woven fabrics, and non-woven fabrics. Suitable materials for the separator 13 include olefin resins such as polyethylene and polypropylene, and cellulose. The separator 13 may have either a single layer structure or a laminated structure. A heat-resistant layer or the like may be formed on the surface of the separator 13 .

EXAMPLES The present disclosure will be further described below with reference to Examples, but the present disclosure is not limited to these Examples.

<Example 1>
[Preparation of positive electrode]
A lithium-containing transition metal composite oxide represented by the general formula LiNi _0.88 Co _0.09 Al _0.03 O ₂ was used as the positive electrode active material. 100 parts by mass of a positive electrode active material, 1 part by mass of acetylene black, and 0.9 parts by mass of polyvinylidene fluoride are mixed, and N-methyl-2-pyrrolidone (NMP) is used as a dispersion medium to prepare a positive electrode mixture. An agent slurry was prepared. Next, the positive electrode mixture slurry is applied to both sides of a positive electrode core made of aluminum foil having a thickness of 15 μm, the coating film is dried and compressed, and then cut into a predetermined electrode size. A positive electrode (thickness: 0.144 mm, width: 62.6 mm, length: 861 mm) on which a mixture layer was formed was produced. An exposed portion where the surface of the core body was exposed was provided in the central portion in the longitudinal direction of the positive electrode, and a positive electrode lead with a width of 3.5 mm was welded to the exposed portion.

[Affixing insulating tape]
As the insulating tape, an adhesive tape including a polyimide base material and an adhesive layer having adhesiveness at room temperature provided on the back surface of the base material was used. The adhesive layers are provided only on both sides in the width direction of the substrate, and a region (concave portion) where no adhesive layer is present is formed with a width of 3.5 mm in the central portion in the width direction of the substrate. An insulating tape was attached to the surface of the positive electrode to which the positive electrode lead was welded so that the positive electrode lead and the exposed portion were covered and the positive electrode lead was fitted into the recess formed on the back surface of the tape.

[Preparation of negative electrode]
As a negative electrode active material, a mixed powder of 95 parts by mass of graphite powder and 5 parts by mass of silicon oxide represented by SiO _x was used. 100 parts by mass of the negative electrode active material, 1 part by mass of carboxymethyl cellulose (CMC), and 1 part by mass of styrene-butadiene rubber (SBR) are mixed, and water is used as a dispersion medium to prepare a negative electrode mixture slurry. bottom. Next, the negative electrode mixture slurry is applied to both sides of a negative electrode core made of copper foil, the coating film is dried and compressed, and then cut into a predetermined electrode size, and negative electrode mixture layers are formed on both sides of the negative electrode core. A formed negative electrode (thickness: 0.160 mm, width: 64.2 mm, length: 959 mm) was produced. In addition, exposed portions where the surface of the core body was exposed were provided at both ends in the longitudinal direction of the negative electrode, and the negative electrode lead was welded to one of the exposed portions.

[Preparation of non-aqueous electrolyte]
Ethylene carbonate (EC) and dimethyl carbonate (DMC) were mixed at a volume ratio of 1:3 in a non-aqueous solvent, vinylene carbonate (VC) was added at a concentration of 5% by mass, and LiPF ₆ was added at 1.5 mol. /L to prepare a non-aqueous electrolytic solution.

[Production of battery]
A wound-type electrode body was produced by spirally winding the positive electrode and the negative electrode with a separator made of polyethylene interposed therebetween. At this time, each electrode was arranged such that the positive electrode mixture layer faced the negative electrode mixture layer with the separator interposed therebetween, and the exposed portion of the negative electrode (the exposed portion where the negative electrode lead was not present) constituted the outer peripheral surface of the electrode body. and a separator. After placing insulating plates above and below the electrode body, the negative electrode lead is welded to the bottom inner surface of a bottomed cylindrical outer can, the positive electrode lead is welded to the inner terminal plate of the sealing body, and the electrode body is placed inside the outer can. accommodated in. After that, a non-aqueous electrolyte is injected into the outer can by a decompression method, and the opening of the outer can is sealed with a sealant through a gasket, thereby producing a cylindrical non-aqueous electrolyte secondary battery (capacity 4600 mAh). bottom.

<Example 2>
A cylindrical non-aqueous electrolyte secondary battery was fabricated in the same manner as in Example 1, except that the width of the concave portion of the insulating tape was changed to 3.7 mm (1.057 times the width of the positive electrode lead).

<Example 3>
A cylindrical non-aqueous electrolyte secondary battery was fabricated in the same manner as in Example 1, except that the width of the concave portion of the insulating tape was changed to 4.0 mm (1.143 times the width of the positive electrode lead).

<Comparative Example 1>
A cylindrical non-aqueous electrolyte secondary battery was produced in the same manner as in Example 1, except that an adhesive layer was provided on the entire back surface of the insulating tape and no concave portion was formed.

<Comparative Example 2>
A cylindrical non-aqueous electrolyte secondary battery was produced in the same manner as in Example 1, except that the width of the concave portion of the insulating tape was changed to 3.0 mm.

[Impact test]
For each battery of Examples and Comparative Examples, a round bar with a diameter of 15.8 mm was arranged in the center in the height direction so as to cross the battery, and a mass of 9.1 kg was obtained from a height of 61 ± 2.5 cm vertically above the round bar. A weight was dropped to give a shock to the battery. Table 1 shows the result of confirming the presence or absence of an internal short circuit for each battery after the impact test.

As shown in Table 1, in the impact test, an internal short circuit was confirmed in the battery of Comparative Example, whereas no internal short circuit was confirmed in the battery of Example. That is, by using an insulating tape in which a region where an adhesive layer does not exist is formed with a width equal to or greater than the width of the lead in the center of the tape substrate in the width direction overlapping the lead, a strong impact force that deforms the battery is applied from the outside. Even if it is added, it is possible to prevent the occurrence of an internal short circuit.

10 secondary battery, 11 positive electrode, 12 negative electrode, 13 separator, 14 electrode body, 16 outer can, 17 sealing body, 18, 19 insulating plate, 20 positive electrode lead, 21 grooved portion, 23 internal terminal plate, 24 lower valve body, 25 insulating member, 26 upper valve body, 27 cap, 28 gasket, 30 positive electrode substrate, 31 positive electrode mixture layer, 32, 42 exposed portion, 40 negative electrode substrate, 41 negative electrode mixture layer, 50 insulating tape, 51 base material , 52 adhesive layer, 53 region

Claims (3)

In a secondary battery comprising an electrode body in which a positive electrode and a negative electrode are wound with a separator interposed therebetween,
The positive electrode and the negative electrode include a core and a mixture layer provided on the surface of the core,
At least one of the positive electrode and the negative electrode is provided with a lead connected to an exposed portion where the surface of the core body is exposed, and an insulating tape covering the lead and the exposed portion,
The insulating tape includes a base material and an adhesive layer provided on one surface of the base material,
On one surface of the base material, the adhesive layers are provided on both sides in the width direction of the base material, and in a center portion in the width direction of the base material that overlaps with the lead, a region where the adhesive layer does not exist is the area of the lead. A secondary battery formed with a width that is 1.05 to 1.50 times the width . 2. The secondary battery according to claim 1, wherein said insulating tape is attached to said positive electrode. 3. The secondary battery according to claim 2, wherein said exposed portion is formed in the longitudinal central portion of said positive electrode.

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