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WO2024181051A1 - Cylindrical battery - Google Patents

Cylindrical battery Download PDF

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Publication number
WO2024181051A1
WO2024181051A1 PCT/JP2024/003825 JP2024003825W WO2024181051A1 WO 2024181051 A1 WO2024181051 A1 WO 2024181051A1 JP 2024003825 W JP2024003825 W JP 2024003825W WO 2024181051 A1 WO2024181051 A1 WO 2024181051A1
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WO
WIPO (PCT)
Prior art keywords
negative electrode
winding
positive electrode
tape
cylindrical battery
Prior art date
Application number
PCT/JP2024/003825
Other languages
French (fr)
Japanese (ja)
Inventor
昂佑 福井
大倫 若林
崇夫 今奥
剛也 伊藤
Original Assignee
パナソニックエナジー株式会社
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Publication date
Application filed by パナソニックエナジー株式会社 filed Critical パナソニックエナジー株式会社
Publication of WO2024181051A1 publication Critical patent/WO2024181051A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/04—Construction or manufacture in general
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H01M10/0587—Construction or manufacture of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators

Definitions

  • This disclosure relates to cylindrical batteries.
  • Cylindrical batteries are equipped with a wound electrode body in which a positive electrode and a negative electrode are wound in a spiral shape with a separator between them.
  • the positive electrode and negative electrode expand and contract, which may cause plate deformation in which at least one of the positive electrode and negative electrode is locally deformed.
  • Patent Document 1 discloses a cylindrical battery equipped with a wound electrode body having an insulating tape attached to the negative electrode so as to straddle the surface of the negative electrode lead in the winding direction in order to suppress deformation of the joint of the negative electrode lead.
  • the winding start end of the positive electrode forms a step along the winding direction, and the negative electrode portion that faces the inside of the winding start end of the positive electrode may deform during charge and discharge cycles. If this deformation of the negative electrode portion occurs, the distance between the positive and negative electrodes may vary, causing uneven charge and discharge reactions and deteriorating cycle characteristics.
  • Patent Document 1 may not be able to sufficiently suppress the deformation of the negative electrode portion that faces the inside of the winding start end of the positive electrode, which causes the step described above.
  • Patent Document 1 raises concerns that the capacity of the cylindrical battery may decrease due to the insulating tape being attached to the negative electrode.
  • the present disclosure therefore aims to provide a cylindrical battery that can suppress deformation of the negative electrode portion that faces the winding start end of the positive electrode that occurs during charge and discharge cycles.
  • the cylindrical battery disclosed herein is a cylindrical battery having an electrode assembly in which a positive electrode and a negative electrode including a core and a mixture layer are spirally wound with a separator interposed therebetween, and the negative electrode is characterized in that it has a tape attached to the inner surface of the winding so as to straddle in the winding direction a first opposing position that faces the inner side of the winding start end of the positive electrode.
  • the cylindrical battery disclosed herein can suppress deformation of the negative electrode portion that faces the winding start end of the positive electrode during charge and discharge cycles.
  • FIG. 2 is an axial cross-sectional view of a cylindrical battery according to an embodiment of the present invention.
  • 4 is a schematic diagram showing a radial cross section of the winding start side of the electrode body.
  • FIG. FIG. 2 is a schematic diagram showing the winding start side of the electrode body in a developed state.
  • FIG. 4 is a schematic diagram showing a radial cross section of FIG. 3 .
  • the cylindrical battery 10 has a positive electrode 11, a negative electrode 12, and a separator 13, and is equipped with an electrode body 14 in which the positive electrode 11 and the negative electrode 12 are wound with the separator 13 interposed therebetween.
  • the cylindrical battery 10 also has a cylindrical outer can 16 with a bottom that houses the electrode body 14, and a sealing body 17 that closes the opening of the outer can 16.
  • the outer can 16 houses an electrolyte together with the electrode body 14.
  • the outer can 16 has a grooved portion 22 formed in its side wall, and the sealing body 17 is supported by the grooved portion 22 to close the opening of the outer can 16.
  • the sealing body 17 side of the cylindrical battery 10 will be referred to as the top, and the bottom side of the outer can 16 will be referred to as the bottom.
  • the negative electrode 12 includes a negative electrode core 40 and a negative electrode mixture layer 41, and has a tape 50 attached to the inner surface of the winding so as to straddle in the winding direction a first opposing position 12A that faces the winding start end 11A of the positive electrode 11.
  • the tape 50 can suppress deformation of the part of the negative electrode 12 that faces the inner surface of the winding start end of the positive electrode 11 due to charge and discharge cycles.
  • the electrolyte may be an aqueous electrolyte, but in this embodiment, a non-aqueous electrolyte is used.
  • the non-aqueous electrolyte has lithium ion conductivity.
  • the non-aqueous electrolyte may be a liquid electrolyte (electrolytic solution) or a solid electrolyte.
  • the cylindrical battery 10 is, for example, a non-aqueous electrolyte secondary battery, and is preferably a lithium ion battery.
  • the liquid electrolyte includes a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent.
  • a non-aqueous solvent for example, esters, ethers, nitriles, amides, and mixed solvents of two or more of these are used as the non-aqueous solvent.
  • the non-aqueous solvent include ethylene carbonate (EC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and mixed solvents of these.
  • the non-aqueous solvent may contain a halogen-substituted product (e.g., fluoroethylene carbonate, etc.) in which at least a part of the hydrogen of these solvents is replaced with a halogen atom such as fluorine.
  • a halogen-substituted product e.g., fluoroethylene carbonate, etc.
  • a lithium salt such as LiPF6 is used as the electrolyte salt.
  • the solid electrolyte for example, a solid or gel-like polymer electrolyte, an inorganic solid electrolyte, etc. can be used.
  • the inorganic solid electrolyte a material known in all-solid-state lithium ion secondary batteries, etc. (for example, an oxide-based solid electrolyte, a sulfide-based solid electrolyte, a halogen-based solid electrolyte, etc.) can be used.
  • the polymer electrolyte includes, for example, a lithium salt and a matrix polymer, or a non-aqueous solvent, a lithium salt, and a matrix polymer.
  • the matrix polymer for example, a polymer material that absorbs a non-aqueous solvent and gels is used.
  • the polymer material for example, a fluororesin, an acrylic resin, a polyether resin, etc. can be used.
  • the electrode body 14 has a wound structure in which the positive electrode 11 and the negative electrode 12 are wound in a spiral shape with the separator 13 interposed therebetween.
  • the positive electrode 11, the negative electrode 12, and the separator 13 are all long strip-shaped bodies, and are wound in a spiral shape so that they are alternately stacked in the radial direction of the electrode body 14.
  • the negative electrode 12 is formed with dimensions slightly larger than the positive electrode 11 to prevent lithium precipitation. In other words, the negative electrode 12 is formed to be longer in the length direction and width direction than the positive electrode 11.
  • the separator 13 is formed with dimensions at least slightly larger than the positive electrode 11, and for example, two separators 13 are arranged to sandwich the positive electrode 11.
  • the electrode body 14 has a positive electrode lead 20 joined to the positive electrode 11 and a negative electrode lead 21 joined to the negative electrode 12.
  • the positive electrode lead 20 is provided in the center of the positive electrode 11 in the longitudinal direction, away from the winding start end and winding end end of the electrode body 14.
  • the negative electrode lead 21 is provided at one longitudinal end of the negative electrode 12 located at the winding start side of the electrode body 14.
  • the negative electrode 12 has a first core exposed portion 43 (see Figures 2 to 4) where the negative electrode mixture layer 41 is not present.
  • the negative electrode lead 21 is joined to the core exposed portion 43.
  • the positive electrode 11 has a positive electrode core 30 and a positive electrode mixture layer 31 formed on at least one surface of the core.
  • the positive electrode core 30 can be made of a foil of a metal such as aluminum or an aluminum alloy that is stable in the potential range of the positive electrode 11, or a film with the metal disposed on the surface.
  • the positive electrode mixture layer 31 contains a positive electrode active material, a conductive agent such as acetylene black, and a binder such as polyvinylidene fluoride (PVdF), and is preferably formed on both sides of the positive electrode core 30.
  • the thickness of the positive electrode mixture layer 31 is, for example, 40 ⁇ m or more and 100 ⁇ m or less.
  • a lithium transition metal complex oxide containing Ni, Co, Mn, Al, etc. is used as the positive electrode active material.
  • the positive electrode lead 20 is preferably directly bonded to the positive electrode core 30 by ultrasonic welding or the like.
  • the negative electrode 12 has a negative electrode core 40 and a negative electrode mixture layer 41 formed on at least one surface of the core.
  • a foil of a metal stable in the potential range of the negative electrode 12, such as copper or a copper alloy, or a film with the metal disposed on the surface layer can be used.
  • the negative electrode mixture layer 41 contains a negative electrode active material and a binder such as styrene-butadiene rubber (SBR), and is preferably formed on both sides of the negative electrode core 40.
  • the thickness of the negative electrode mixture layer 41 is, for example, 40 ⁇ m or more and 100 ⁇ m or less.
  • graphite, a Si-containing material, etc. are used as the negative electrode active material.
  • the negative electrode lead 21 is preferably directly bonded to the negative electrode core 40 by ultrasonic welding or the like.
  • the cylindrical battery 10 is provided with an upper insulating plate 18 that is disposed between the sealing body 17 and the electrode group and has an opening through which the positive electrode lead 20 passes.
  • the electrode group refers to the portion of the electrode body 14 that is composed of the positive electrode 11, the negative electrode 12, and the separator 13, excluding the positive electrode lead 20 and the negative electrode lead 21.
  • the cylindrical battery 10 also has a lower insulating plate 19 that is disposed between the bottom of the outer can 16 and the electrode group and has an opening through which the negative electrode lead 21 passes.
  • the positive electrode lead 20 extends through the opening of the upper insulating plate 18 toward the sealing body 17, and the negative electrode lead 21 extends through the opening of the lower insulating plate 19 toward the bottom side of the outer can 16.
  • the positive electrode lead 20 is connected to the underside of the bottom plate 23 of the sealing body 17 by welding or the like, and the sealing body 17 serves as the positive electrode terminal.
  • the negative electrode lead 21 is connected to the inner bottom surface of the outer can 16 by welding or the like, and the outer can 16 serves as the negative electrode terminal.
  • the negative electrode 12 is disposed on the outermost surface of the electrode body 14, and a second core exposed portion 44 is provided where the surface of the negative electrode core 40 is exposed.
  • the core exposed portion 44 abuts against the inner surface of the exterior can 16.
  • the core exposed portion 44 abuts against the inner surface of the exterior can 16, which is the negative electrode terminal, electrically connecting both ends in the length direction of the negative electrode 12 to the exterior can 16, ensuring good current collection.
  • the core exposed portion 44 may be provided on a part of the outermost surface of the electrode body 14, but is preferably provided over the entire outermost surface. For example, a portion where the negative electrode mixture layer 41 is not present is provided on both sides of the negative electrode core 40 for a length of at least one revolution of the electrode body 14 from the winding end of the negative electrode 12.
  • the outer can 16 is a cylindrical metal container with a bottom.
  • a gasket 28 is provided between the outer can 16 and the sealing body 17 to seal the inside of the battery.
  • the outer can 16 has a grooved portion 22 formed, for example, by pressing the side portion from the outside.
  • the grooved portion 22 is preferably formed in an annular shape along the circumferential direction of the outer can 16, and supports the sealing body 17 on its upper surface.
  • the upper end of the outer can 16 is bent inward and crimped to the peripheral edge of the sealing body 17.
  • the sealing body 17 has a structure in which, in order from the electrode body 14 side, a bottom plate 23, a lower valve body 24, an insulating member 25, an upper valve body 26, and a cap 27 are stacked.
  • Each member constituting the sealing body 17 has, for example, a disk or ring shape, and each member except for the insulating member 25 is electrically connected to each other.
  • the lower valve body 24 and the upper valve body 26 are connected to each other at their respective centers, and the insulating member 25 is interposed between their respective peripheral edges.
  • Fig. 2 is a cross-sectional view perpendicular to the winding axis direction of the winding start side of the electrode body 14 (a cross-sectional view along the lamination direction of the electrode body 14).
  • Fig. 3 is a schematic view showing the winding start side of the electrode body 14 in a developed state.
  • Fig. 4 is a schematic view showing a radial cross-section of Fig. 3. In Figs. 2 to 4, the separator 13 is omitted for clarity of the drawings.
  • the tape 50 is attached to the inner surface of the negative electrode 12 at the start of winding. More specifically, the tape 50 is attached so as to straddle the position of the inner surface of the negative electrode 12 that faces the inner surface of the start of winding end 11A of the positive electrode 11. In other words, the start of winding end 50A of the tape 50 is located closer to the start of winding than the first opposing position 12A, and the end of winding end 50B of the tape 50 is located closer to the end of winding than the first opposing position 12A. As described above, the start of winding end 11A of the positive electrode 11 has a positive electrode mixture layer 31 formed on the positive electrode core 30.
  • the winding start end 11A of the positive electrode 11 forms a step along the winding direction, so when charge/discharge cycles are repeated, the part of the negative electrode 12 that faces the inside of the winding start end of the positive electrode may deform. If this part of the negative electrode 12 deforms, the distance between the positive and negative electrodes may vary, causing uneven charge/discharge reactions and deteriorating cycle characteristics.
  • the tape 50 reinforces the portion of the negative electrode 12 that faces the inside of the winding start end 11A of the positive electrode 11, which is the step described above, and can suppress deformation of that portion of the negative electrode 12. This suppresses variation in the distance between the positive and negative electrodes, and can suppress uneven charge/discharge reactions and deterioration of cycle characteristics.
  • the tape 50 is attached to the inner surface of the negative electrode 12 at the beginning of winding, which does not contribute to the electrolytic reaction, so the electrolytic reaction is not hindered by the tape 50, and a decrease in the battery capacity of the cylindrical battery 10 can be avoided.
  • the winding end 50B of the tape 50 is located 2 mm or more toward the winding end side from the first opposing position 12A. This ensures that the portion of the negative electrode 12 that faces the winding start end 11A of the positive electrode 11, which becomes the step described above, can be reinforced reliably.
  • the winding end 50B of the tape 50 is located closer to the winding start side than the second opposing position 12B.
  • the tape 50 is attached so as not to face the positive electrode 11 of the negative electrode 12 via the separator 13. This prevents the tape 50 from interfering with the electrolytic reaction, and prevents a decrease in the battery capacity of the cylindrical battery 10.
  • the winding start end 50A of the tape 50 is located closer to the winding start side than the winding start end 41A of the negative electrode mixture layer 41 on the inner winding surface of the negative electrode 12. More specifically, the winding start end 50A is preferably located 2 mm or more closer to the winding start side than the winding start end 41A of the negative electrode mixture layer 41. This makes it possible to more reliably reinforce the portion of the negative electrode 12 that faces the winding start end 11A of the positive electrode 11.
  • the winding start end 50A of the tape 50 is located closer to the winding end than the negative electrode lead 21. In other words, it is preferable that the winding start end 50A of the tape 50 does not straddle the negative electrode lead 21. This makes it possible to avoid the tape 50 becoming unnecessarily long.
  • the length (width) of the tape 50 in the direction of the winding axis will be described in detail.
  • the length of the tape 50 in the direction of the winding axis is preferably 60% or more, and more preferably 80% or more, of the length of the negative electrode 12 in the direction of the winding axis.
  • the center position of the tape 50 in the direction of the winding axis and the center position of the negative electrode 12 in the direction of the winding axis are approximately the same. This makes it possible to more reliably reinforce the portion of the negative electrode 12 that faces the winding start end 11A of the positive electrode 11.
  • the tape 50 is preferably insulating. However, when the tape 50 is attached to the negative electrode 12 in a region that does not face the positive electrode 12 via the separator 13, it does not need to have any particular insulating properties.
  • the tape 50 includes, for example, a tape base material and an adhesive layer formed on one side of the base material, and is attached to the inner surface of the roll of the negative electrode 12 via the adhesive layer.
  • polyesters such as polyethylene terephthalate (PET), polypropylene (PP), polyimide (PI), polyphenylene sulfide (PPS), polyetherimide (PEI), polyamide, etc.
  • the adhesive constituting the adhesive layer is one that exerts adhesive strength at room temperature.
  • adhesives include acrylic adhesives and synthetic rubber adhesives.
  • the tape 50 may also contain insulating inorganic fillers.
  • Lithium nickel oxide (LiNi 0.88 Co 0.09 Al 0.03 O 2 ) containing cobalt and aluminum was used as the positive electrode active material.
  • the positive electrode active material, acetylene black, and polyvinylidene fluoride were mixed in a solid content mass ratio of 98:1:1, and a positive electrode mixture slurry was prepared using N-methylpyrrolidone (NMP) as a dispersion medium.
  • NMP N-methylpyrrolidone
  • the slurry was applied to both sides of a positive electrode core made of a long aluminum foil with a thickness of 15 ⁇ m, and the coating was dried and compressed to obtain a positive electrode (width 58.0 mm, length 850 mm, thickness 110 ⁇ m) in which a positive electrode mixture layer was formed on both sides of the positive electrode core.
  • a core exposed portion where no positive electrode mixture layer exists was provided in the center of the length direction of the positive electrode, and an aluminum positive electrode lead was ultrasonically welded to the exposed portion, and PI tape was attached to both sides to protect the current collector exposed portion.
  • the negative electrode active material As the negative electrode active material, a mixture of graphite powder and a Si-containing material in a mass ratio of 95:5 was used. The negative electrode active material, a dispersion of styrene butadiene rubber, and sodium carboxymethylcellulose were mixed in a solid content mass ratio of 98:1:1, and a negative electrode mixture slurry was prepared using water as a dispersion medium.
  • the slurry was applied to both sides of a negative electrode core made of a long copper foil with a thickness of 8 ⁇ m, and the coating film was dried and compressed to obtain a negative electrode (width 59.3 mm, length 955 mm, thickness 114 ⁇ m) in which a negative electrode mixture layer was formed on both sides of the negative electrode core.
  • first and second core exposed parts in which a negative electrode mixture layer does not exist were provided within a predetermined length range from both ends of the negative electrode in the longitudinal direction, and a nickel negative electrode lead was ultrasonically welded to the first core exposed part.
  • the positive electrode, the negative electrode, and the polyethylene separator were spirally wound around a cylindrical winding core member to obtain a wound electrode body.
  • the negative electrode was arranged so that the first core exposed portion of the negative electrode to which the negative electrode lead was joined was located at the start of winding the electrode body. That is, the second core exposed portion of the negative electrode was located at the end of winding the electrode body.
  • the winding core member was removed to obtain a wound electrode body with a cavity formed in the winding core portion.
  • tape was applied to the inner surface of the negative electrode from the end of the winding of the negative electrode lead, straddling the negative electrode mixture layer.
  • the tape was positioned so that the end of the tape was closer to the start of winding than the first opposing position, which is the position facing the inside of the winding start end of the negative electrode and then the positive electrode (so as not to overlap with the first opposing position).
  • the tape used was made of polypropylene and had a thickness of 0.03 mm.
  • the length of the tape in the winding axis direction was 50 mm.
  • VC vinylene carbonate
  • DMC dimethyl carbonate
  • the negative electrode lead was welded to the inner bottom surface of a cylindrical outer can with a bottom, and the positive electrode lead was welded to the internal terminal plate of the sealing body to house the electrode body in the outer can.
  • a nonaqueous electrolyte was injected into the outer can under reduced pressure, and the opening of the outer can was sealed with the sealing body via a gasket to obtain a cylindrical battery.
  • the second core exposed portion of the negative electrode forms the outermost surface of the electrode body and is in contact with the inner surface of the outer can.
  • Example 2 A cylindrical battery was fabricated in the same manner as in Example 1, except that the winding end of the tape was positioned 2 mm toward the winding end from the first opposing position.
  • Example 3 A cylindrical battery was fabricated in the same manner as in Experimental Example 2, except that the length of the tape in the direction of the winding axis was 30 mm.
  • Configuration 1 A cylindrical battery including an electrode body in which a positive electrode and a negative electrode including a core and a mixture layer are spirally wound with a separator interposed therebetween, the negative electrode having a tape attached to an inner surface of the negative electrode so as to straddle in the winding direction a first opposing position that faces the inner side of the winding start end of the positive electrode.
  • Configuration 2 The cylindrical battery according to configuration 1, wherein the end of the tape winding is located 2 mm or more toward the winding end side from the first opposing position.
  • Configuration 3 The cylindrical battery according to configuration 1 or 2, wherein the winding start end of the tape is located closer to the winding start side than the winding start end of the mixture layer on the inner surface of the roll.
  • Configuration 4 The cylindrical battery according to any one of configurations 1 to 3, wherein the length of the tape in the direction of the winding axis is 60% or more of the length of the negative electrode in the direction of the winding axis.
  • Configuration 5 The cylindrical battery according to any one of configurations 1 to 4, wherein the winding end of the tape is located on the winding start side of a second opposing position of the negative electrode that faces the outer side of the winding start end of the positive electrode.

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Abstract

A cylindrical battery (10) comprising a winding-type electrode body (14) in which a positive electrode (11) and a negative electrode (12), which includes a negative electrode core (40) and a negative electrode mixture layer (41), are spirally wound via a separator (13), wherein the negative electrode (12) has a tape (50) which is pasted to a winding inner surface so as to extend in the winding direction across a first facing position (12A) facing the winding inner side of a winding start-side end (11A) of the positive electrode (11).

Description

円筒形電池Cylindrical battery
　本開示は、円筒形電池に関する。 This disclosure relates to cylindrical batteries.
　円筒形電池は、正極と負極とがセパレータを介して渦巻き状に巻回された巻回型の電極体を備える。円筒形電池では、充放電サイクルが繰り返されると、正極および負極が膨張収縮し、正極および負極の少なくとも一方が局所的に変形する極板変形が生じる場合がある。 Cylindrical batteries are equipped with a wound electrode body in which a positive electrode and a negative electrode are wound in a spiral shape with a separator between them. In cylindrical batteries, when charge/discharge cycles are repeated, the positive electrode and negative electrode expand and contract, which may cause plate deformation in which at least one of the positive electrode and negative electrode is locally deformed.
　例えば、特許文献１には、負極リードの接合部分の変形を抑制するために、負極リードの表面を巻き方向に跨ぐように、負極に貼着された絶縁テープを有する巻回型の電極体を備えた円筒形電池が開示されている。 For example, Patent Document 1 discloses a cylindrical battery equipped with a wound electrode body having an insulating tape attached to the negative electrode so as to straddle the surface of the negative electrode lead in the winding direction in order to suppress deformation of the joint of the negative electrode lead.
国際公開第２０１８／１８０７４８号International Publication No. 2018/180748
　ところで、円筒形電池では、正極の巻き始め側端部が巻回方向に沿って段差となるため、充放電サイクルに伴って、正極の巻き始め側端部の巻内側と対向する負極部分が変形する場合がある。当該負極部分の変形が生じた場合には、正負極間の距離がばらついて、充放電反応が不均一となり、サイクル特性が悪化するおそれがある。 In cylindrical batteries, the winding start end of the positive electrode forms a step along the winding direction, and the negative electrode portion that faces the inside of the winding start end of the positive electrode may deform during charge and discharge cycles. If this deformation of the negative electrode portion occurs, the distance between the positive and negative electrodes may vary, causing uneven charge and discharge reactions and deteriorating cycle characteristics.
　特許文献１の絶縁テープでは、上述した段差となる正極の巻き始め側端の巻き内側と対向する負極部分の変形を十分に抑制することができない場合がある。また、特許文献１では、絶縁テープが負極に貼着されることによって、円筒形電池の容量が低下する懸念がある。 The insulating tape of Patent Document 1 may not be able to sufficiently suppress the deformation of the negative electrode portion that faces the inside of the winding start end of the positive electrode, which causes the step described above. In addition, Patent Document 1 raises concerns that the capacity of the cylindrical battery may decrease due to the insulating tape being attached to the negative electrode.
　そこで、本開示は、充放電サイクルに伴う正極の巻き始め側端部と対向する負極部分の変形を抑制することができる円筒形電池を提供することを目的とする。 The present disclosure therefore aims to provide a cylindrical battery that can suppress deformation of the negative electrode portion that faces the winding start end of the positive electrode that occurs during charge and discharge cycles.
　本開示に係る円筒形電池は、正極と、芯体および合剤層を含む負極とが、セパレータを介して渦巻き状に巻回された電極体を備えた円筒形電池であって、負極は、正極の巻き始め側端の巻内側と対向する第１対向位置を巻回方向に跨ぐように巻内面に貼着されたテープを有することを特徴とする。 The cylindrical battery disclosed herein is a cylindrical battery having an electrode assembly in which a positive electrode and a negative electrode including a core and a mixture layer are spirally wound with a separator interposed therebetween, and the negative electrode is characterized in that it has a tape attached to the inner surface of the winding so as to straddle in the winding direction a first opposing position that faces the inner side of the winding start end of the positive electrode.
　本開示の円筒形電池によれば、充放電サイクルに伴う正極の巻き始め側端部と対向する負極部分の変形を抑制することができる。 The cylindrical battery disclosed herein can suppress deformation of the negative electrode portion that faces the winding start end of the positive electrode during charge and discharge cycles.
実施形態の一例である円筒形電池の軸方向断面図である。FIG. 2 is an axial cross-sectional view of a cylindrical battery according to an embodiment of the present invention. 電極体の巻き始め側の径方向断面を示す模式図である。4 is a schematic diagram showing a radial cross section of the winding start side of the electrode body. FIG. 電極体の巻き始め側を展開して示す模式図である。FIG. 2 is a schematic diagram showing the winding start side of the electrode body in a developed state. 図３の径方向断面を示す模式図である。FIG. 4 is a schematic diagram showing a radial cross section of FIG. 3 .
　以下、本開示の実施形態の一例について詳細に説明する。以下の説明において、具体的な形状、材料、方向、数値等は、本開示の理解を容易にするための例示であって、用途、目的、仕様等に合わせて適宜変更することができる。 Below, an example of an embodiment of the present disclosure is described in detail. In the following description, specific shapes, materials, directions, numerical values, etc. are examples to facilitate understanding of the present disclosure, and can be modified as appropriate according to the application, purpose, specifications, etc.
　［円筒形電池］
　図１を用いて、実施形態の一例である円筒形電池１０について説明する。 [Cylindrical battery]
A cylindrical battery 10 as one example of the embodiment will be described with reference to FIG.
　円筒形電池１０は、正極１１と、負極１２と、セパレータ１３とを有し、正極１１と負極１２がセパレータ１３を介して巻回された電極体１４を備える。また、円筒形電池１０は、電極体１４を収容する有底円筒状の外装缶１６と、外装缶１６の開口部を塞ぐ封口体１７とを備える。外装缶１６には、電極体１４と共に電解質が収容されている。外装缶１６は側壁に形成された溝入部２２を有し、封口体１７は溝入部２２に支持されて外装缶１６の開口部を塞いでいる。以下では、説明の便宜上、円筒形電池１０の封口体１７側を上、外装缶１６の底部側を下とする。 The cylindrical battery 10 has a positive electrode 11, a negative electrode 12, and a separator 13, and is equipped with an electrode body 14 in which the positive electrode 11 and the negative electrode 12 are wound with the separator 13 interposed therebetween. The cylindrical battery 10 also has a cylindrical outer can 16 with a bottom that houses the electrode body 14, and a sealing body 17 that closes the opening of the outer can 16. The outer can 16 houses an electrolyte together with the electrode body 14. The outer can 16 has a grooved portion 22 formed in its side wall, and the sealing body 17 is supported by the grooved portion 22 to close the opening of the outer can 16. In the following, for ease of explanation, the sealing body 17 side of the cylindrical battery 10 will be referred to as the top, and the bottom side of the outer can 16 will be referred to as the bottom.
　詳細は後述するが、負極１２は、負極芯体４０および負極合剤層４１を含み、正極１１の巻き始め側端１１Ａと対向する第１対向位置１２Ａを巻回方向に跨ぐように巻内面に貼着されたテープ５０を有する。テープ５０によれば、充放電サイクルに伴う正極１１の巻き始め側端部の巻内側と対向する負極１２の部分の変形を抑制することができる。 Although details will be described later, the negative electrode 12 includes a negative electrode core 40 and a negative electrode mixture layer 41, and has a tape 50 attached to the inner surface of the winding so as to straddle in the winding direction a first opposing position 12A that faces the winding start end 11A of the positive electrode 11. The tape 50 can suppress deformation of the part of the negative electrode 12 that faces the inner surface of the winding start end of the positive electrode 11 due to charge and discharge cycles.
　電解質は、水系電解質であってもよいが、本実施形態では非水電解質を用いるものとする。非水電解質は、リチウムイオン伝導性を有する。非水電解質は、液状の電解質（電解液）であってもよく、固体電解質であってもよい。円筒形電池１０は、例えば、非水電解質二次電池であって、中でもリチウムイオン電池であることが好ましい。 The electrolyte may be an aqueous electrolyte, but in this embodiment, a non-aqueous electrolyte is used. The non-aqueous electrolyte has lithium ion conductivity. The non-aqueous electrolyte may be a liquid electrolyte (electrolytic solution) or a solid electrolyte. The cylindrical battery 10 is, for example, a non-aqueous electrolyte secondary battery, and is preferably a lithium ion battery.
　液状の電解質（電解液）は、非水溶媒と、非水溶媒に溶解した電解質塩とを含む。非水溶媒には、例えば、エステル類、エーテル類、ニトリル類、アミド類、およびこれらの２種以上の混合溶媒等が用いられる。非水溶媒の一例としては、エチレンカーボネート（ＥＣ）、エチルメチルカーボネート（ＥＭＣ）、ジメチルカーボネート（ＤＭＣ）、ジエチルカーボネート（ＤＥＣ）、およびこれらの混合溶媒等が挙げられる。非水溶媒は、これら溶媒の水素の少なくとも一部をフッ素等のハロゲン原子で置換したハロゲン置換体（例えば、フルオロエチレンカーボネート等）を含有していてもよい。電解質塩には、例えば、ＬｉＰＦ６等のリチウム塩が使用される。 The liquid electrolyte (electrolytic solution) includes a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. For example, esters, ethers, nitriles, amides, and mixed solvents of two or more of these are used as the non-aqueous solvent. Examples of the non-aqueous solvent include ethylene carbonate (EC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and mixed solvents of these. The non-aqueous solvent may contain a halogen-substituted product (e.g., fluoroethylene carbonate, etc.) in which at least a part of the hydrogen of these solvents is replaced with a halogen atom such as fluorine. For example, a lithium salt such as LiPF6 is used as the electrolyte salt.
　固体電解質としては、例えば、固体状もしくはゲル状のポリマー電解質、無機固体電解質等を用いることができる。無機固体電解質としては、全固体リチウムイオン二次電池等で公知の材料（例えば、酸化物系固体電解質、硫化物系固体電解質、ハロゲン系固体電解質等）を用いることができる。ポリマー電解質は、例えば、リチウム塩とマトリックスポリマー、あるいは非水溶媒とリチウム塩とマトリックスポリマーとを含む。マトリックスポリマーとしては、例えば、非水溶媒を吸収してゲル化するポリマー材料が使用される。ポリマー材料としては、フッ素樹脂、アクリル樹脂、ポリエーテル樹脂等が挙げられる。 As the solid electrolyte, for example, a solid or gel-like polymer electrolyte, an inorganic solid electrolyte, etc. can be used. As the inorganic solid electrolyte, a material known in all-solid-state lithium ion secondary batteries, etc. (for example, an oxide-based solid electrolyte, a sulfide-based solid electrolyte, a halogen-based solid electrolyte, etc.) can be used. The polymer electrolyte includes, for example, a lithium salt and a matrix polymer, or a non-aqueous solvent, a lithium salt, and a matrix polymer. As the matrix polymer, for example, a polymer material that absorbs a non-aqueous solvent and gels is used. As the polymer material, for example, a fluororesin, an acrylic resin, a polyether resin, etc. can be used.
　電極体１４は、上記のように、正極１１と負極１２がセパレータ１３を介して渦巻き状に巻回された巻回構造を有する。正極１１、負極１２、およびセパレータ１３は、いずれも帯状の長尺体であって、渦巻状に巻回されることで電極体１４の径方向に交互に積層されている。負極１２は、リチウムの析出を防止するために、正極１１よりも一回り大きな寸法で形成される。即ち、負極１２は、正極１１よりも長さ方向および幅方向に長く形成される。セパレータ１３は、少なくとも正極１１よりも一回り大きな寸法で形成され、例えば、正極１１を挟むように２枚配置される。 As described above, the electrode body 14 has a wound structure in which the positive electrode 11 and the negative electrode 12 are wound in a spiral shape with the separator 13 interposed therebetween. The positive electrode 11, the negative electrode 12, and the separator 13 are all long strip-shaped bodies, and are wound in a spiral shape so that they are alternately stacked in the radial direction of the electrode body 14. The negative electrode 12 is formed with dimensions slightly larger than the positive electrode 11 to prevent lithium precipitation. In other words, the negative electrode 12 is formed to be longer in the length direction and width direction than the positive electrode 11. The separator 13 is formed with dimensions at least slightly larger than the positive electrode 11, and for example, two separators 13 are arranged to sandwich the positive electrode 11.
　電極体１４は、正極１１に接合された正極リード２０と、負極１２に接合された負極リード２１とを有する。本実施形態では、正極リード２０が正極１１の長さ方向中央部であって、電極体１４の巻き始め側端および巻き終り側端から離れた位置に設けられている。他方、負極リード２１は電極体１４の巻き始め側に位置する負極１２の長さ方向一端部に設けられている。負極１２は、負極合剤層４１が存在しない第１の芯体露出部４３（図２から図４参照）を有する。負極リード２１は、芯体露出部４３に接合されている。 The electrode body 14 has a positive electrode lead 20 joined to the positive electrode 11 and a negative electrode lead 21 joined to the negative electrode 12. In this embodiment, the positive electrode lead 20 is provided in the center of the positive electrode 11 in the longitudinal direction, away from the winding start end and winding end end of the electrode body 14. On the other hand, the negative electrode lead 21 is provided at one longitudinal end of the negative electrode 12 located at the winding start side of the electrode body 14. The negative electrode 12 has a first core exposed portion 43 (see Figures 2 to 4) where the negative electrode mixture layer 41 is not present. The negative electrode lead 21 is joined to the core exposed portion 43.
　正極１１は、正極芯体３０と、当該芯体の少なくとも一方の面に形成された正極合剤層３１とを有する。正極芯体３０には、アルミニウム、アルミニウム合金等、正極１１の電位範囲で安定な金属の箔、当該金属を表層に配置したフィルム等を用いることができる。正極合剤層３１は、正極活物質、アセチレンブラック等の導電剤、およびポリフッ化ビニリデン（ＰＶｄＦ）等の結着剤を含み、正極芯体３０の両面に形成されることが好ましい。正極合剤層３１の厚みは、例えば、４０μｍ以上１００μｍ以下である。正極活物質には、例えば、Ｎｉ、Ｃｏ、Ｍｎ、Ａｌ等を含有するリチウム遷移金属複合酸化物が用いられる。なお、正極リード２０は、超音波溶着等により正極芯体３０に直接接合されていることが好ましい。 The positive electrode 11 has a positive electrode core 30 and a positive electrode mixture layer 31 formed on at least one surface of the core. The positive electrode core 30 can be made of a foil of a metal such as aluminum or an aluminum alloy that is stable in the potential range of the positive electrode 11, or a film with the metal disposed on the surface. The positive electrode mixture layer 31 contains a positive electrode active material, a conductive agent such as acetylene black, and a binder such as polyvinylidene fluoride (PVdF), and is preferably formed on both sides of the positive electrode core 30. The thickness of the positive electrode mixture layer 31 is, for example, 40 μm or more and 100 μm or less. For example, a lithium transition metal complex oxide containing Ni, Co, Mn, Al, etc. is used as the positive electrode active material. The positive electrode lead 20 is preferably directly bonded to the positive electrode core 30 by ultrasonic welding or the like.
　負極１２は、負極芯体４０と、当該芯体の少なくとも一方の面に形成された負極合剤層４１とを有する。負極芯体４０には、銅、銅合金等、負極１２の電位範囲で安定な金属の箔、当該金属を表層に配置したフィルム等を用いることができる。負極合剤層４１は、負極活物質、およびスチレン－ブタジエンゴム（ＳＢＲ）等の結着剤を含み、負極芯体４０の両面に形成されることが好ましい。負極合剤層４１の厚みは、例えば、４０μｍ以上１００μｍ以下である。負極活物質には、例えば、黒鉛、Ｓｉ含有材料等が用いられる。負極リード２１は、超音波溶着等により負極芯体４０に直接接合されていることが好ましい。 The negative electrode 12 has a negative electrode core 40 and a negative electrode mixture layer 41 formed on at least one surface of the core. For the negative electrode core 40, a foil of a metal stable in the potential range of the negative electrode 12, such as copper or a copper alloy, or a film with the metal disposed on the surface layer can be used. The negative electrode mixture layer 41 contains a negative electrode active material and a binder such as styrene-butadiene rubber (SBR), and is preferably formed on both sides of the negative electrode core 40. The thickness of the negative electrode mixture layer 41 is, for example, 40 μm or more and 100 μm or less. For example, graphite, a Si-containing material, etc. are used as the negative electrode active material. The negative electrode lead 21 is preferably directly bonded to the negative electrode core 40 by ultrasonic welding or the like.
　円筒形電池１０は、封口体１７と電極群との間に配置され、正極リード２０を通す開口部を有する上部絶縁板１８を備える。本明細書において、電極群とは、電極体１４のうち、正極１１、負極１２、およびセパレータ１３から構成される部分であって、正極リード２０および負極リード２１を除く部分を意味する。また、円筒形電池１０は、外装缶１６の底部と電極群との間に配置され、負極リード２１を通す開口部を有する下部絶縁板１９を備える。 The cylindrical battery 10 is provided with an upper insulating plate 18 that is disposed between the sealing body 17 and the electrode group and has an opening through which the positive electrode lead 20 passes. In this specification, the electrode group refers to the portion of the electrode body 14 that is composed of the positive electrode 11, the negative electrode 12, and the separator 13, excluding the positive electrode lead 20 and the negative electrode lead 21. The cylindrical battery 10 also has a lower insulating plate 19 that is disposed between the bottom of the outer can 16 and the electrode group and has an opening through which the negative electrode lead 21 passes.
　図１に示す例では、正極リード２０が上部絶縁板１８の開口部を通って封口体１７側に延び、負極リード２１が下部絶縁板１９の開口部を通って外装缶１６の底部側に延びている。正極リード２０は封口体１７の底板２３の下面に溶接等で接続され、封口体１７が正極端子となる。負極リード２１は外装缶１６の底部内面に溶接等で接続され、外装缶１６が負極端子となる。 In the example shown in FIG. 1, the positive electrode lead 20 extends through the opening of the upper insulating plate 18 toward the sealing body 17, and the negative electrode lead 21 extends through the opening of the lower insulating plate 19 toward the bottom side of the outer can 16. The positive electrode lead 20 is connected to the underside of the bottom plate 23 of the sealing body 17 by welding or the like, and the sealing body 17 serves as the positive electrode terminal. The negative electrode lead 21 is connected to the inner bottom surface of the outer can 16 by welding or the like, and the outer can 16 serves as the negative electrode terminal.
　電極体１４の最外周面には、負極１２が配置され、かつ負極芯体４０の表面が露出した第２の芯体露出部４４が設けられている。そして、芯体露出部４４は、外装缶１６の内周面に当接している。芯体露出部４４が負極端子である外装缶１６の内周面に当接することで、負極１２の長さ方向の両端部と外装缶１６が電気的に接続され良好な集電性を確保できる。芯体露出部４４は、電極体１４の最外周面の一部に設けられてもよいが、好ましくは最外周面の全域に設けられる。例えば、負極１２の巻き終わり端から電極体１４の１周分以上の長さで負極芯体４０の両面に負極合剤層４１が存在しない部分が設けられる。 The negative electrode 12 is disposed on the outermost surface of the electrode body 14, and a second core exposed portion 44 is provided where the surface of the negative electrode core 40 is exposed. The core exposed portion 44 abuts against the inner surface of the exterior can 16. The core exposed portion 44 abuts against the inner surface of the exterior can 16, which is the negative electrode terminal, electrically connecting both ends in the length direction of the negative electrode 12 to the exterior can 16, ensuring good current collection. The core exposed portion 44 may be provided on a part of the outermost surface of the electrode body 14, but is preferably provided over the entire outermost surface. For example, a portion where the negative electrode mixture layer 41 is not present is provided on both sides of the negative electrode core 40 for a length of at least one revolution of the electrode body 14 from the winding end of the negative electrode 12.
　外装缶１６は、有底円筒形状の金属製容器である。外装缶１６と封口体１７との間にはガスケット２８が設けられ、電池内部が密閉される。外装缶１６は、例えば、側面部を外側からプレスして形成された溝入部２２を有する。溝入部２２は、外装缶１６の周方向に沿って環状に形成されることが好ましく、その上面で封口体１７を支持する。また、外装缶１６の上端部は、内側に折り曲げられ封口体１７の周縁部に加締められている。 The outer can 16 is a cylindrical metal container with a bottom. A gasket 28 is provided between the outer can 16 and the sealing body 17 to seal the inside of the battery. The outer can 16 has a grooved portion 22 formed, for example, by pressing the side portion from the outside. The grooved portion 22 is preferably formed in an annular shape along the circumferential direction of the outer can 16, and supports the sealing body 17 on its upper surface. In addition, the upper end of the outer can 16 is bent inward and crimped to the peripheral edge of the sealing body 17.
　封口体１７は、電極体１４側から順に、底板２３、下弁体２４、絶縁部材２５、上弁体２６、およびキャップ２７が積層された構造を有する。封口体１７を構成する各部材は、例えば円板形状又はリング形状を有し、絶縁部材２５を除く各部材は互いに電気的に接続されている。下弁体２４と上弁体２６は各々の中央部で互いに接続され、各々の周縁部の間には絶縁部材２５が介在している。電池の内圧が上昇すると、下弁体２４が上弁体２６をキャップ２７側に押し上げるように変形して破断することにより、下弁体２４と上弁体２６の間の電流経路が遮断される。さらに内圧が上昇すると、上弁体２６が破断し、キャップ２７の開口部からガスが排出される。 The sealing body 17 has a structure in which, in order from the electrode body 14 side, a bottom plate 23, a lower valve body 24, an insulating member 25, an upper valve body 26, and a cap 27 are stacked. Each member constituting the sealing body 17 has, for example, a disk or ring shape, and each member except for the insulating member 25 is electrically connected to each other. The lower valve body 24 and the upper valve body 26 are connected to each other at their respective centers, and the insulating member 25 is interposed between their respective peripheral edges. When the internal pressure of the battery increases, the lower valve body 24 deforms and breaks so as to push the upper valve body 26 toward the cap 27, thereby cutting off the current path between the lower valve body 24 and the upper valve body 26. When the internal pressure increases further, the upper valve body 26 breaks, and gas is discharged from the opening of the cap 27.
　［テープ］
　図２から図４を用いて、テープ５０について説明する。図２は、電極体１４の巻き始め側の巻回軸方向に垂直な断面図（電極体１４の積層方向に沿った断面図）である。図３は、電極体１４の巻き始め側を展開して示す模式図である。図４は、図３の径方向断面を示す模式図である。図２から図４では、図面の明瞭化のため、セパレータ１３の図示を省略している。 [tape]
The tape 50 will be described with reference to Fig. 2 to Fig. 4. Fig. 2 is a cross-sectional view perpendicular to the winding axis direction of the winding start side of the electrode body 14 (a cross-sectional view along the lamination direction of the electrode body 14). Fig. 3 is a schematic view showing the winding start side of the electrode body 14 in a developed state. Fig. 4 is a schematic view showing a radial cross-section of Fig. 3. In Figs. 2 to 4, the separator 13 is omitted for clarity of the drawings.
　テープ５０は、負極１２の巻き始め側の巻内面に貼着される。より詳細には、テープ５０は、負極１２の巻内面のうち正極１１の巻き始め側端１１Ａの巻内側と対向する位置を跨ぐように貼着される。つまり、テープ５０の巻き始め側端５０Ａは、第１対向位置１２Ａよりも巻き始め側に位置し、テープ５０の巻き終わり側端５０Ｂは、第１対向位置１２Ａよりも巻き終わり側に位置する。なお、正極１１の巻き始め側端１１Ａには、上述したように正極芯体３０に正極合剤層３１が形成されている。 The tape 50 is attached to the inner surface of the negative electrode 12 at the start of winding. More specifically, the tape 50 is attached so as to straddle the position of the inner surface of the negative electrode 12 that faces the inner surface of the start of winding end 11A of the positive electrode 11. In other words, the start of winding end 50A of the tape 50 is located closer to the start of winding than the first opposing position 12A, and the end of winding end 50B of the tape 50 is located closer to the end of winding than the first opposing position 12A. As described above, the start of winding end 11A of the positive electrode 11 has a positive electrode mixture layer 31 formed on the positive electrode core 30.
　ここで、円筒形電池１０では、正極１１の巻き始め側端１１Ａが巻回方向に沿って段差となるため、充放電サイクルが繰り返されると、正極の巻き始め側端部の巻内側と対向する負極１２の部分が変形する場合がある。当該負極１２の部分の変形が生じた場合には、正負極間の距離がばらついて、充放電反応が不均一となり、サイクル特性が悪化するおそれがある。 In the cylindrical battery 10, the winding start end 11A of the positive electrode 11 forms a step along the winding direction, so when charge/discharge cycles are repeated, the part of the negative electrode 12 that faces the inside of the winding start end of the positive electrode may deform. If this part of the negative electrode 12 deforms, the distance between the positive and negative electrodes may vary, causing uneven charge/discharge reactions and deteriorating cycle characteristics.
　テープ５０によれば、上述した段差となる正極１１の巻き始め側端１１Ａの巻内側と対向する負極１２の部分を補強することによって、当該負極１２の部分の変形を抑制することができる。これにより、正負極間の距離のばらつきを抑制し、充放電反応が不均一となり、サイクル特性が悪化することを抑制することができる。 The tape 50 reinforces the portion of the negative electrode 12 that faces the inside of the winding start end 11A of the positive electrode 11, which is the step described above, and can suppress deformation of that portion of the negative electrode 12. This suppresses variation in the distance between the positive and negative electrodes, and can suppress uneven charge/discharge reactions and deterioration of cycle characteristics.
　また、テープ５０は、電解反応に寄与しない負極１２の巻き始め側の負極１２の巻内面に貼着されるため、テープ５０によって電解反応が妨げられることがなく、円筒形電池１０の電池容量の低下を回避することができる。 In addition, the tape 50 is attached to the inner surface of the negative electrode 12 at the beginning of winding, which does not contribute to the electrolytic reaction, so the electrolytic reaction is not hindered by the tape 50, and a decrease in the battery capacity of the cylindrical battery 10 can be avoided.
　ここで、テープ５０の巻き終わり側端５０Ｂの位置について詳細に説明する。テープ５０の巻き終わり側端５０Ｂは、第１対向位置１２Ａよりも２ｍｍ以上巻き終わり側に位置する。これにより、上述した段差となる正極１１の巻き始め側端１１Ａと対向する負極１２の部分を確実に補強することができる。 Here, the position of the winding end 50B of the tape 50 will be described in detail. The winding end 50B of the tape 50 is located 2 mm or more toward the winding end side from the first opposing position 12A. This ensures that the portion of the negative electrode 12 that faces the winding start end 11A of the positive electrode 11, which becomes the step described above, can be reinforced reliably.
　また、テープ５０の巻き終わり側端５０Ｂは、第２対向位置１２Ｂより巻き始め側に位置する。つまり、テープ５０は、負極１２のうちセパレータ１３を介して正極１１と対向しないように貼着される。これにより、テープ５０によって電解反応が妨げられることがなく、円筒形電池１０の電池容量の低下を回避することができる。 Furthermore, the winding end 50B of the tape 50 is located closer to the winding start side than the second opposing position 12B. In other words, the tape 50 is attached so as not to face the positive electrode 11 of the negative electrode 12 via the separator 13. This prevents the tape 50 from interfering with the electrolytic reaction, and prevents a decrease in the battery capacity of the cylindrical battery 10.
　次に、テープ５０の巻き始め側端５０Ａの位置について詳細に説明する。テープ５０の巻き始め側端５０Ａは、負極１２の巻内面の負極合剤層４１の巻き始め側端４１Ａよりも巻き始め側に位置する。より詳細には、巻き始め側端５０Ａは、負極合剤層４１の巻き始め側端４１Ａよりも２ｍｍ以上巻き始め側に位置することが好ましい。これにより、正極１１の巻き始め側端部１１Ａと対向する負極１２の部分をより確実に補強することができる。 Next, the position of the winding start end 50A of the tape 50 will be described in detail. The winding start end 50A of the tape 50 is located closer to the winding start side than the winding start end 41A of the negative electrode mixture layer 41 on the inner winding surface of the negative electrode 12. More specifically, the winding start end 50A is preferably located 2 mm or more closer to the winding start side than the winding start end 41A of the negative electrode mixture layer 41. This makes it possible to more reliably reinforce the portion of the negative electrode 12 that faces the winding start end 11A of the positive electrode 11.
　また、テープ５０の巻き始め側端５０Ａは、負極リード２１よりも巻き終わり側に位置することが好ましい。換言すれば、テープ５０の巻き始め側端５０Ａは、負極リード２１を跨がないことが好ましい。これにより、無駄にテープ５０が長くなることを回避することができる。 Furthermore, it is preferable that the winding start end 50A of the tape 50 is located closer to the winding end than the negative electrode lead 21. In other words, it is preferable that the winding start end 50A of the tape 50 does not straddle the negative electrode lead 21. This makes it possible to avoid the tape 50 becoming unnecessarily long.
　さらに、テープ５０の巻回軸方向の長さ（幅）について詳細に説明する。テープ５０の巻回軸方向の長さは、負極１２の巻回軸方向の長さの６０％以上であることが好ましく、８０％以上であることがより好ましい。また、テープ５０の巻回軸方向の中心位置と、負極１２の巻回軸方向の中心位置とは、略一致していることが好ましい。これにより、正極１１の巻き始め側端１１Ａと対向する負極１２の部分をより確実に補強することができる。 Furthermore, the length (width) of the tape 50 in the direction of the winding axis will be described in detail. The length of the tape 50 in the direction of the winding axis is preferably 60% or more, and more preferably 80% or more, of the length of the negative electrode 12 in the direction of the winding axis. In addition, it is preferable that the center position of the tape 50 in the direction of the winding axis and the center position of the negative electrode 12 in the direction of the winding axis are approximately the same. This makes it possible to more reliably reinforce the portion of the negative electrode 12 that faces the winding start end 11A of the positive electrode 11.
　テープ５０は絶縁性を有することが好ましい。しかし、テープ５０が負極１２のうちセパレータ１３を介して正極１２に対向しない範囲に貼着される場合、特に絶縁性能を有する必要はない。テープ５０は、例えば、テープ基材と、基材の片面に形成された粘着剤層とを含み、粘着剤層を介して負極１２の巻内面に貼着される。 The tape 50 is preferably insulating. However, when the tape 50 is attached to the negative electrode 12 in a region that does not face the positive electrode 12 via the separator 13, it does not need to have any particular insulating properties. The tape 50 includes, for example, a tape base material and an adhesive layer formed on one side of the base material, and is attached to the inner surface of the roll of the negative electrode 12 via the adhesive layer.
　テープ基材を構成する樹脂としては、ポリエチレンテレフタレート（ＰＥＴ）等のポリエステル、ポリプロピレン（ＰＰ）、ポリイミド（ＰＩ）、ポリフェニレンサルファイド（ＰＰＳ）、ポリエーテルイミド（ＰＥＩ）、ポリアミド等が例示できる。粘着剤層を構成する粘着剤は、室温で粘着力を発揮するものが好ましい。粘着剤の一例は、アクリル系粘着剤、合成ゴム系粘着剤等である。なお、テープ５０には、絶縁性の無機物フィラーが含有されていてもよい。 Examples of resins constituting the tape base material include polyesters such as polyethylene terephthalate (PET), polypropylene (PP), polyimide (PI), polyphenylene sulfide (PPS), polyetherimide (PEI), polyamide, etc. It is preferable that the adhesive constituting the adhesive layer is one that exerts adhesive strength at room temperature. Examples of adhesives include acrylic adhesives and synthetic rubber adhesives. The tape 50 may also contain insulating inorganic fillers.
　なお、本開示は上述した実施形態およびその変形例に限定されるものではなく、本願の特許請求の範囲に記載された事項の範囲内において種々の変更や改良が可能であることは勿論である。 Note that this disclosure is not limited to the above-described embodiment and its variations, and various modifications and improvements are possible within the scope of the matters described in the claims of this application.
　以下、実験例により本開示をさらに説明するが、本開示はこれらの実験例に限定されるものではない。 The present disclosure will be further explained below using experimental examples, but the present disclosure is not limited to these experimental examples.
　＜実験例１＞
　［正極の作製］
　正極活物質として、コバルトおよびアルミニウムを含有するニッケル酸リチウム（ＬｉＮｉ０．８８Ｃｏ０．０９Ａｌ０．０３Ｏ２）を用いた。正極活物質と、アセチレンブラックと、ポリフッ化ビニリデンとを、９８：１：１の固形分質量比で混合し、分散媒としてＮ－メチルピロリドン（ＮＭＰ）を用いて正極合剤スラリーを調製した。当該スラリーを厚み１５μｍの長尺状のアルミニウム箔からなる正極芯体の両面に塗布し、塗膜を乾燥、圧縮して、正極芯体の両面に正極合剤層が形成された正極（幅５８．０ｍｍ、長さ８５０ｍｍ、厚み１１０μｍ）を得た。なお、正極の長さ方向中央部に正極合剤層が存在しない芯体露出部を設け、当該露出部にアルミニウム製の正極リードを超音波溶着し、集電体露出部を保護するためにＰＩテープを両面に貼り付けた。 <Experimental Example 1>
[Preparation of Positive Electrode]
Lithium nickel oxide (LiNi 0.88 Co 0.09 Al 0.03 O 2 ) containing cobalt and aluminum was used as the positive electrode active material. The positive electrode active material, acetylene black, and polyvinylidene fluoride were mixed in a solid content mass ratio of 98:1:1, and a positive electrode mixture slurry was prepared using N-methylpyrrolidone (NMP) as a dispersion medium. The slurry was applied to both sides of a positive electrode core made of a long aluminum foil with a thickness of 15 μm, and the coating was dried and compressed to obtain a positive electrode (width 58.0 mm, length 850 mm, thickness 110 μm) in which a positive electrode mixture layer was formed on both sides of the positive electrode core. In addition, a core exposed portion where no positive electrode mixture layer exists was provided in the center of the length direction of the positive electrode, and an aluminum positive electrode lead was ultrasonically welded to the exposed portion, and PI tape was attached to both sides to protect the current collector exposed portion.
　［負極の作製］
　負極活物質として、黒鉛粉末とＳｉ含有材料を９５：５の質量比で混合したものを用いた。負極活物質と、スチレンブタジエンゴムのディスパージョンと、カルボキシメチルセルロースナトリウムとを、９８：１：１の固形分質量比で混合し、分散媒として水を用いて負極合剤スラリーを調製した。当該スラリーを厚み８μｍの長尺状の銅箔からなる負極芯体の両面に塗布し、塗膜を乾燥、圧縮して、負極芯体の両面に負極合剤層が形成された負極（幅５９．３ｍｍ、長さ９５５ｍｍ、厚み１１４μｍ）を得た。なお、負極の長さ方向両端から所定の長さ範囲に負極合剤層が存在しない第１および第２の芯体露出部を設け、第１の芯体露出部にニッケル製の負極リードを超音波溶着した。 [Preparation of negative electrode]
As the negative electrode active material, a mixture of graphite powder and a Si-containing material in a mass ratio of 95:5 was used. The negative electrode active material, a dispersion of styrene butadiene rubber, and sodium carboxymethylcellulose were mixed in a solid content mass ratio of 98:1:1, and a negative electrode mixture slurry was prepared using water as a dispersion medium. The slurry was applied to both sides of a negative electrode core made of a long copper foil with a thickness of 8 μm, and the coating film was dried and compressed to obtain a negative electrode (width 59.3 mm, length 955 mm, thickness 114 μm) in which a negative electrode mixture layer was formed on both sides of the negative electrode core. In addition, first and second core exposed parts in which a negative electrode mixture layer does not exist were provided within a predetermined length range from both ends of the negative electrode in the longitudinal direction, and a nickel negative electrode lead was ultrasonically welded to the first core exposed part.
　［電極体の作製］
　上記正極、上記負極、およびポリエチレン製のセパレータを円柱状の巻き芯部材を用いて渦巻き状に巻回して巻回型の電極体を得た。このとき、負極リードが接合された負極の第１の芯体露出部が電極体の巻き始め側に位置するように負極を配置した。即ち、負極の第２の芯体露出部は電極体の巻き終わり側に位置する。電極体の巻回構造を形成した後、巻き芯部材を取り外して、巻き芯部分に空洞が形成された巻回型の電極体を得た。 [Preparation of electrode body]
The positive electrode, the negative electrode, and the polyethylene separator were spirally wound around a cylindrical winding core member to obtain a wound electrode body. At this time, the negative electrode was arranged so that the first core exposed portion of the negative electrode to which the negative electrode lead was joined was located at the start of winding the electrode body. That is, the second core exposed portion of the negative electrode was located at the end of winding the electrode body. After forming the winding structure of the electrode body, the winding core member was removed to obtain a wound electrode body with a cavity formed in the winding core portion.
　実験例１では、負極リードの巻き終わり側から負極合剤層を跨ぐように負極の巻内面にテープを貼り付けた。このとき、テープの巻き終わり側端が負極のちの正極の巻き始め側端の巻内側との対向位置である第１対向位置よりも巻き始め側になるように（第１対向位置と重ならないように）テープを配置した。テープは、ポリプロピレン製で厚み０．０３ｍｍを使用した。テープの巻回軸方向の長さは５０ｍｍの寸法とした。 In Experimental Example 1, tape was applied to the inner surface of the negative electrode from the end of the winding of the negative electrode lead, straddling the negative electrode mixture layer. The tape was positioned so that the end of the tape was closer to the start of winding than the first opposing position, which is the position facing the inside of the winding start end of the negative electrode and then the positive electrode (so as not to overlap with the first opposing position). The tape used was made of polypropylene and had a thickness of 0.03 mm. The length of the tape in the winding axis direction was 50 mm.
　［非水電解液の調製］
　エチレンカーボネート（ＥＣ）と、ジメチルカーボネート（ＤＭＣ）とを１：３の体積比（２５℃）で混合した混合溶媒１００質量部に、ビニレンカーボネート（ＶＣ）５質量部を添加し、ＬｉＰＦ６を１．３モル／リットル溶解して非水電解液を調製した。 [Preparation of non-aqueous electrolyte]
5 parts by mass of vinylene carbonate (VC) was added to 100 parts by mass of a mixed solvent obtained by mixing ethylene carbonate (EC) and dimethyl carbonate (DMC) in a volume ratio of 1:3 (25 ° C.), and 1.3 mol/L of LiPF6 was dissolved therein to prepare a nonaqueous electrolyte solution.
　［円筒形電池の作製］
　上記電極体の上下に絶縁板を配置した後、負極リードを有底円筒形状の外装缶の缶底内面に溶接し、正極リードを封口体の内部端子板に溶接して、電極体を外装缶内に収容した。その後、外装缶内に非水電解液を減圧方式で注入し、ガスケットを介して外装缶の開口部を封口体で封止することにより円筒形電池を得た。なお、負極の第２の芯体露出部は、電極体の最外周面を形成し、外装缶の内周面に接触している。 [Preparation of cylindrical battery]
After placing insulating plates above and below the electrode body, the negative electrode lead was welded to the inner bottom surface of a cylindrical outer can with a bottom, and the positive electrode lead was welded to the internal terminal plate of the sealing body to house the electrode body in the outer can. After that, a nonaqueous electrolyte was injected into the outer can under reduced pressure, and the opening of the outer can was sealed with the sealing body via a gasket to obtain a cylindrical battery. The second core exposed portion of the negative electrode forms the outermost surface of the electrode body and is in contact with the inner surface of the outer can.
　＜実験例２＞
　テープの巻き終わり側端を第１対向位置よりも２ｍｍだけ巻き終わり側に配置したこと以外は、実施例１と同様にして円筒形電池を作製した。 <Experimental Example 2>
A cylindrical battery was fabricated in the same manner as in Example 1, except that the winding end of the tape was positioned 2 mm toward the winding end from the first opposing position.
　＜実験例３＞
　テープの巻回軸方向の長さを３０ｍｍとしたこと以外は、実験例２と同様にして円筒形電池を作製した。 <Experimental Example 3>
A cylindrical battery was fabricated in the same manner as in Experimental Example 2, except that the length of the tape in the direction of the winding axis was 30 mm.
　［極板変形（座屈の有無）の評価］
　各実験例の電池を、以下の条件の充放電サイクルを２００回実施した。その後Ｘ線ＣＴ装置を用いて電池の中央部の断面観察を実施して正極の巻き始め側端部の巻内側と対向する負極部分の変形を確認した。
　充電：３０００ｍＡ（１Ｃ）－４．２０Ｖ　１００ｍＡ　ｃｕｔ　休止３０分
　放電：１５０００ｍＡ（５Ｃ）－２．５０Ｖ　ｃｕｔ　休止６０分 [Evaluation of electrode plate deformation (presence or absence of buckling)]
The batteries of each experimental example were subjected to 200 charge/discharge cycles under the following conditions. Then, a cross-section of the center of the battery was observed using an X-ray CT device to confirm deformation of the negative electrode portion facing the inside of the winding start end of the positive electrode.
Charging: 3000mA (1C) -4.20V 100mA cut 30 minutes break Discharging: 15000mA (5C) -2.50V cut 60 minutes break
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　表１に示すように、実験例１、３の電池では、正極の巻き始め側端部の巻内側と対向する負極部分が巻内側に屈折する座屈変形が見られた。実験例２の電池では、当該負極部分において座屈変形が見られなかった。 As shown in Table 1, in the batteries of Experimental Examples 1 and 3, buckling deformation was observed in which the negative electrode portion facing the inside of the winding start end of the positive electrode was bent toward the inside of the winding. In the battery of Experimental Example 2, no buckling deformation was observed in the negative electrode portion.
　また、本開示は、以下の実施形態によりさらに説明される。
　構成１：正極と、芯体および合剤層を含む負極とが、セパレータを介して渦巻き状に巻回された電極体を備えた円筒形電池であって、前記負極は、前記正極の巻き始め側端の巻内側と対向する第１対向位置を巻回方向に跨ぐように巻内面に貼着されたテープを有する、円筒形電池。
　構成２：前記テープの巻き終わり側端は、前記第１対向位置よりも２ｍｍ以上巻き終わり側に位置する、構成１に記載の円筒形電池。
　構成３：前記テープの巻き始め側端部は、巻内面の前記合剤層の巻き始め側端部よりも巻き始め側に位置する、構成１または２に記載の円筒形電池。
　構成４：前記テープの巻回軸方向の長さは、前記負極の巻回軸方向の長さの６０％以上である、構成１から３のいずれか一項に記載の円筒形電池。
　構成５：前記テープの巻き終わり側端は、前記負極のうち前記正極の巻き始め側端の巻外側に対向する第２対向位置より巻き始め側に位置する、構成１から４のいずれか一項に記載の円筒形電池。 The present disclosure is further illustrated by the following embodiments.
Configuration 1: A cylindrical battery including an electrode body in which a positive electrode and a negative electrode including a core and a mixture layer are spirally wound with a separator interposed therebetween, the negative electrode having a tape attached to an inner surface of the negative electrode so as to straddle in the winding direction a first opposing position that faces the inner side of the winding start end of the positive electrode.
Configuration 2: The cylindrical battery according to configuration 1, wherein the end of the tape winding is located 2 mm or more toward the winding end side from the first opposing position.
Configuration 3: The cylindrical battery according to configuration 1 or 2, wherein the winding start end of the tape is located closer to the winding start side than the winding start end of the mixture layer on the inner surface of the roll.
Configuration 4: The cylindrical battery according to any one of configurations 1 to 3, wherein the length of the tape in the direction of the winding axis is 60% or more of the length of the negative electrode in the direction of the winding axis.
Configuration 5: The cylindrical battery according to any one of configurations 1 to 4, wherein the winding end of the tape is located on the winding start side of a second opposing position of the negative electrode that faces the outer side of the winding start end of the positive electrode.
　１０　円筒形電池、１１　正極、１１Ａ　巻き始め側端（正極）、１２　負極、１２Ａ　第１対向位置、１２Ｂ　第２対向位置、１３　セパレータ、１４　電極体、１６　外装缶、１７　封口体、１８　上部絶縁板、１９　下部絶縁板、２０　正極リード、２１　負極リード、２２　溝入部、２３　底板、２４　下弁体、２５　絶縁部材、２６　上弁体、２７　キャップ、２８　ガスケット、３０　正極芯体、３１　正極合剤層、４０　負極芯体、４１　負極合剤層、４１Ａ　巻き始め側端（負極合剤層）、４３　芯体露出部（第１）、４４　芯体露出部（第２）、５０　テープ、５０Ａ　巻き始め側端（テープ）、５０Ｂ　巻き終わり側端部（テープ）
  10 Cylindrical battery, 11 Positive electrode, 11A Winding start end (positive electrode), 12 Negative electrode, 12A First opposing position, 12B Second opposing position, 13 Separator, 14 Electrode body, 16 Outer can, 17 Sealing body, 18 Upper insulating plate, 19 Lower insulating plate, 20 Positive electrode lead, 21 Negative electrode lead, 22 Grooved portion, 23 Bottom plate, 24 Lower valve body, 25 Insulating member, 26 Upper valve body, 27 Cap, 28 Gasket, 30 Positive electrode core, 31 Positive electrode mixture layer, 40 Negative electrode core, 41 Negative electrode mixture layer, 41A Winding start end (negative electrode mixture layer), 43 Core exposed portion (first), 44 Core exposed portion (second), 50 Tape, 50A Winding start end (tape), 50B Winding end (tape)

Claims (5)

  1. 　正極と、芯体および合剤層を含む負極とが、セパレータを介して渦巻き状に巻回された電極体を備えた円筒形電池であって、
    　前記負極は、前記正極の巻き始め側端の巻内側と対向する第１対向位置を巻回方向に跨ぐように巻内面に貼着されたテープを有する、
    　円筒形電池。     A cylindrical battery including an electrode assembly in which a positive electrode, a negative electrode including a core and a mixture layer are spirally wound with a separator interposed therebetween,
    The negative electrode has a tape attached to an inner surface of the winding so as to straddle in the winding direction a first opposing position that faces the inner side of the winding start end of the positive electrode.
    Cylindrical battery.
  2. 　請求項１に記載の円筒形電池であって、
    　前記テープの巻き終わり側端は、前記第１対向位置よりも２ｍｍ以上巻き終わり側に位置する、
    　円筒形電池。     2. The cylindrical battery according to claim 1,
    the end of the tape is located 2 mm or more toward the end of the tape from the first opposing position;
    Cylindrical battery.
  3. 　請求項２に記載の円筒形電池であって、
    　前記テープの巻き始め側端は、巻内面の前記合剤層の巻き始め側端よりも巻き始め側に位置する、
    　円筒形電池。     3. The cylindrical battery according to claim 2,
    the winding start end of the tape is located closer to the winding start end of the mixture layer on the inner surface of the roll;
    Cylindrical battery.
  4. 　請求項３に記載の円筒形電池であって、
    　前記テープの巻回軸方向の長さは、前記負極の巻回軸方向の長さの６０％以上である、
    　円筒形電池。     4. The cylindrical battery according to claim 3,
    The length of the tape in the winding axis direction is 60% or more of the length of the negative electrode in the winding axis direction.
    Cylindrical battery.
  5. 　請求項１から４のいずれか一項に記載の円筒形電池であって、
    　前記テープの巻き終わり側端は、前記負極のうち前記正極の巻き始め側端の巻外側に対向する第２対向位置より巻き始め側に位置する、
    　円筒形電池。
          A cylindrical battery according to any one of claims 1 to 4,
    the winding end of the tape is located on the winding start side of a second opposing position of the negative electrode that faces the outer side of the winding start end of the positive electrode,
    Cylindrical battery.
PCT/JP2024/003825 2023-02-27 2024-02-06 Cylindrical battery WO2024181051A1 (en)

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2018180748A1 (en) * 2017-03-28 2018-10-04 三洋電機株式会社 Secondary battery using non-aqueous electrolyte
JP2020080250A (en) * 2018-11-13 2020-05-28 三洋電機株式会社 Cylindrical secondary battery

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2018180748A1 (en) * 2017-03-28 2018-10-04 三洋電機株式会社 Secondary battery using non-aqueous electrolyte
JP2020080250A (en) * 2018-11-13 2020-05-28 三洋電機株式会社 Cylindrical secondary battery

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