WO2019049485A1 - Secondary battery - Google Patents

Secondary battery Download PDF

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Publication number
WO2019049485A1
WO2019049485A1 PCT/JP2018/024997 JP2018024997W WO2019049485A1 WO 2019049485 A1 WO2019049485 A1 WO 2019049485A1 JP 2018024997 W JP2018024997 W JP 2018024997W WO 2019049485 A1 WO2019049485 A1 WO 2019049485A1
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WO
WIPO (PCT)
Prior art keywords
layer
positive electrode
negative electrode
insulating tape
secondary battery
Prior art date
Application number
PCT/JP2018/024997
Other languages
French (fr)
Japanese (ja)
Inventor
一洋 吉井
貴夫 佐藤
Original Assignee
パナソニックＩｐマネジメント株式会社
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Publication of WO2019049485A1 publication Critical patent/WO2019049485A1/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
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/572—Means for preventing undesired use or discharge
    • H01M50/584—Means for preventing undesired use or discharge for preventing incorrect connections inside or outside the batteries
    • H01M50/586—Means for preventing undesired use or discharge for preventing incorrect connections inside or outside the batteries inside the batteries, e.g. incorrect connections of electrodes
    • 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
    • H01M10/60—Heating or cooling; Temperature control
    • H01M10/64—Heating or cooling; Temperature control characterised by the shape of the cells
    • H01M10/643—Cylindrical cells
    • 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
    • H01M10/60—Heating or cooling; Temperature control
    • H01M10/65—Means for temperature control structurally associated with the cells
    • H01M10/651—Means for temperature control structurally associated with the cells characterised by parameters specified by a numeric value or mathematical formula, e.g. ratios, sizes or concentrations
    • 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
    • H01M10/60—Heating or cooling; Temperature control
    • H01M10/65—Means for temperature control structurally associated with the cells
    • H01M10/653—Means for temperature control structurally associated with the cells characterised by electrically insulating or thermally conductive materials
    • 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
    • H01M10/60—Heating or cooling; Temperature control
    • H01M10/65—Means for temperature control structurally associated with the cells
    • H01M10/655—Solid structures for heat exchange or heat conduction
    • H01M10/6553—Terminals or leads
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/531—Electrode connections inside a battery casing
    • H01M50/534—Electrode connections inside a battery casing characterised by the material of the leads or tabs
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/531—Electrode connections inside a battery casing
    • H01M50/536—Electrode connections inside a battery casing characterised by the method of fixing the leads to the electrodes, e.g. by welding
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/572—Means for preventing undesired use or discharge
    • H01M50/584—Means for preventing undesired use or discharge for preventing incorrect connections inside or outside the batteries
    • H01M50/59—Means for preventing undesired use or discharge for preventing incorrect connections inside or outside the batteries characterised by the protection means
    • H01M50/595—Tapes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present disclosure relates to a secondary battery.
  • a lithium secondary battery has been proposed in which the insulation properties of the positive electrode or the negative electrode are improved by using an insulating tape.
  • Patent Document 1 discloses a non-aqueous electrolyte secondary battery including an insulating tape having a multilayer structure including an organic material layer mainly composed of an organic material and a composite material layer containing an organic material and an inorganic material. ing.
  • the secondary battery according to one aspect of the present disclosure is a secondary battery including an electrode body in which a positive electrode and a negative electrode are stacked via a separator, wherein the positive electrode and the negative electrode are a current collector, and the current collector.
  • the insulating tape includes an insulating tape attached to at least one side, and the insulating tape is interposed between a substrate layer made of an insulating organic material, an adhesive layer, the substrate layer, and the adhesive layer.
  • a thermally conductive layer containing at least one of a carbonaceous filler and a metallic filler as the thermally conductive filler.
  • the secondary battery according to another aspect of the present disclosure is a secondary battery including an electrode body in which a positive electrode and a negative electrode are stacked via a separator, wherein the positive electrode and the negative electrode are a current collector, and the collector is A composite material layer formed on a current collector, and an electrode lead connected to an exposed portion where the surface of the current collector is exposed, wherein at least one of the positive electrode and the negative electrode, the electrode lead and the exposure Between the base material layer made of an insulating organic material, an adhesive layer, the base material layer, and the adhesive layer. And a thermally conductive layer made of metal foil.
  • internal short circuit can be suppressed while maintaining good battery performance. Further, even if an internal short circuit occurs, the rise in battery temperature can be suppressed.
  • the secondary battery according to the present disclosure uses a thermally conductive layer containing at least one of a carbon-based filler and a metal filler or an insulating tape having a thermally conductive layer composed of a metal foil to maintain good battery performance while maintaining good battery performance.
  • the heat generation due to the short circuit can be highly suppressed. Since the carbon-based filler, the metal filler, and the metal foil hardly adsorb moisture, the insulating tape does not increase the amount of moisture in the battery. For this reason, in the secondary battery according to the present disclosure, a failure due to the intrusion of moisture is unlikely to occur, and good battery performance is maintained. In addition, the fall of the discharge capacity when it preserve
  • the battery case is, for example, a resin made of a square metal case (square battery) and a resin film. It may be a case (laminated battery) or the like.
  • FIG. 1 is a cross-sectional view of a secondary battery 10 which is an example of the embodiment.
  • the secondary battery 10 includes an electrode body 14, an electrolyte (not shown), and a battery case that accommodates the electrode body 14 and the electrolyte.
  • a preferred example of the secondary battery 10 is a lithium ion battery.
  • the electrode body 14 has a wound structure in which the positive electrode 11 and the negative electrode 12 are wound via the separator 13.
  • the battery case is configured of a bottomed cylindrical case main body 15 and a sealing body 16 that closes the opening of the main body.
  • the electrolyte comprises a solvent and an electrolyte salt dissolved in the solvent.
  • the solvent for example, nonaqueous solvents such as esters, ethers, nitriles, amides, and mixed solvents of two or more of them, and water may be used.
  • the solvent may contain a halogen substitute wherein at least a part of hydrogen of these solvents is substituted with a halogen atom such as fluorine.
  • the electrolyte is not limited to the liquid electrolyte, and may be a solid electrolyte using a gel polymer or the like.
  • a lithium salt such as LiPF 6 is used for example.
  • the secondary battery 10 includes insulating plates 17 and 18 disposed above and below the electrode body 14.
  • the positive electrode lead 19 extends through the through hole of the insulating plate 17 toward the sealing body 16
  • the negative electrode lead 20 extends through the outside of the insulating plate 18 toward the bottom of the case body 15.
  • the positive electrode lead 19 is connected to the lower surface of the filter 22 which is a bottom plate of the sealing member 16 by welding or the like, and a cap 26 which is a top plate of the sealing member 16 electrically connected to the filter 22 serves as a positive electrode terminal.
  • the negative electrode lead 20 is connected to the inner surface of the bottom of the case main body 15 by welding or the like, and the case main body 15 becomes a negative electrode terminal.
  • the case main body 15 is, for example, a metal container with a bottomed cylindrical shape.
  • a gasket 27 is provided between the case main body 15 and the sealing body 16 to ensure the airtightness inside the battery case.
  • the case main body 15 has an overhanging portion 21 for supporting the sealing body 16 which is formed, for example, by pressing the side surface portion from the outside.
  • the projecting portion 21 is preferably formed in an annular shape along the circumferential direction of the case main body 15, and the sealing member 16 is supported on the upper surface thereof.
  • the sealing body 16 has a structure in which the filter 22, the lower valve body 23, the insulating member 24, the upper valve body 25, and the cap 26 are sequentially stacked from the electrode body 14 side.
  • Each member which comprises the sealing body 16 has disk shape or ring shape, for example, and each member except the insulation member 24 is electrically connected mutually.
  • the lower valve body 23 and the upper valve body 25 are connected to each other at their central portions, and an insulating member 24 is interposed between the respective peripheral edge portions. Since the lower valve body 23 is provided with a vent, if the internal pressure of the battery rises due to abnormal heat generation, the upper valve body 25 bulges to the cap 26 side and separates from the lower valve body 23 so that the electrical connection between them is achieved. It is cut off. When the internal pressure further increases, the upper valve body 25 is broken, and the gas is discharged from the opening of the cap 26.
  • FIG. 2 is a front view of the positive electrode 11 and the negative electrode 12 constituting the electrode assembly 14, and the right side of the drawing is the core side.
  • the negative electrode 12 is formed larger than the positive electrode 11 in order to prevent deposition of lithium on the negative electrode 12, and the negative electrode current collector 35 of the negative electrode 12 A current collector longer in width and wider than the positive electrode current collector 30 is used. Then, at least a portion where the positive electrode mixture layer 31 of the positive electrode 11 is formed is opposed to a portion where the negative electrode mixture layer 36 of the negative electrode 12 is formed via the separator 13.
  • the positive electrode 11 includes a positive electrode current collector 30, a positive electrode mixture layer 31 formed on the positive electrode current collector 30, and a positive electrode lead 19 connected to the exposed portion 32 where the surface of the positive electrode current collector 30 is exposed.
  • the positive electrode mixture layer 31 is formed on both surfaces of the strip-shaped positive electrode current collector 30.
  • a foil of a metal such as aluminum, a film in which the metal is disposed on the surface, or the like is used.
  • the thickness of the positive electrode current collector 30 is, for example, 5 ⁇ m to 30 ⁇ m.
  • the positive electrode mixture layer 31 is preferably formed on the entire surface of the positive electrode current collector 30 except for the exposed portion 32.
  • the positive electrode mixture layer 31 contains a positive electrode active material, a conductive material such as carbon black or acetylene black, and a binder such as polyvinylidene fluoride (PVdF).
  • a positive electrode active material lithium metal complex oxide containing metallic elements, such as Co, Mn, Ni, and Al, can be illustrated.
  • the positive electrode 11 applies a positive electrode mixture slurry containing a positive electrode active material, a conductive material, a binder, and a dispersion medium such as N-methyl-2-pyrrolidone (NMP) on both sides of the positive electrode current collector 30, and the coating is compressed.
  • NMP N-methyl-2-pyrrolidone
  • the exposed portion 32 is a portion in which the surface of the positive electrode current collector 30 is not covered by the positive electrode mixture layer 31.
  • the exposed portion 32 is formed wider than the positive electrode lead 19, for example, across the entire width of the positive electrode 11.
  • the exposed portions 32 are preferably provided on both sides of the positive electrode 11 so as to overlap in the thickness direction of the positive electrode 11. In the example shown in FIG. 2, one exposed portion 32 is provided on one side of the positive electrode 11 at the central portion in the longitudinal direction of the positive electrode 11.
  • the negative electrode 12 includes a negative electrode current collector 35, a negative electrode mixture layer 36 formed on the negative electrode current collector 35, and a negative electrode lead 20 connected to the exposed portion 37 where the surface of the negative electrode current collector 35 is exposed.
  • the negative electrode mixture layer 36 is formed on both sides of the strip-like negative electrode current collector 35.
  • a foil of a metal such as copper, a film in which the metal is disposed on the surface, or the like is used.
  • the thickness of the negative electrode current collector 35 is, for example, 5 ⁇ m to 30 ⁇ m.
  • the negative electrode mixture layer 36 is preferably formed on the entire surface of the negative electrode current collector 35 except for the exposed portion 37.
  • the negative electrode mixture layer 36 contains a negative electrode active material and a binder such as styrene-butadiene rubber (SBR).
  • SBR styrene-butadiene rubber
  • the negative electrode active material is not particularly limited as long as it can occlude and release lithium ions reversibly, for example, carbon materials such as natural graphite and artificial graphite, metals alloyed with lithium such as Si and Sn, or these Alloys, complex oxides, etc. can be used.
  • the negative electrode 12 can be prepared by applying a negative electrode mixture slurry containing a negative electrode active material, a binder, water, and the like on both sides of the negative electrode current collector 35 and compressing the coating film.
  • the exposed portion 37 is a portion where the surface of the negative electrode current collector 35 is not covered by the negative electrode mixture layer 36.
  • the exposed portion 37 is formed wider than the negative electrode lead 20, for example, across the entire width of the negative electrode 12.
  • one exposed portion 37 is provided on one side of the negative electrode 12 at one end in the longitudinal direction of the negative electrode 12 and located on the winding outer side of the electrode body 14.
  • the exposed portion 37 may be provided at the end of the negative electrode 12 (the other end in the longitudinal direction of the negative electrode 12) located on the winding core side of the electrode body 14 and provided at both longitudinal ends of the negative electrode 12 May be
  • the positive electrode lead 19 and the negative electrode lead 20 are strip-like conductive members that are thicker than the current collector and the mixture layer.
  • the thickness of the lead is, for example, 50 ⁇ m to 500 ⁇ m.
  • the constituent material of each lead is not particularly limited, but it is preferable that the positive electrode lead 19 be made of a metal whose main component is aluminum, and the negative electrode lead 20 be a metal whose main component is nickel or copper.
  • the number, arrangement, and the like of the leads are not particularly limited.
  • the secondary battery 10 includes an insulating tape 40 attached to at least one of the electrode lead and the exposed portion in at least one of the positive electrode 11 and the negative electrode 12.
  • the insulating tape 40 is preferably attached to at least a part of a portion (hereinafter, may be referred to as a “base”) located on the current collector among the electrode leads.
  • the base of the electrode lead is generally welded to the exposed portions 32, 37, but the whole may not be welded.
  • a part of the positive electrode lead 19 extends from the upper end of the positive electrode current collector 30 and is connected to the sealing member 16, and a part of the negative electrode lead 20 extends from the lower end of the negative electrode current collector 35 and the bottom of the case main body 15 It is connected to the inner surface (hereinafter, a part of the part may be referred to as an “extension part”).
  • the insulating tape 40 is attached to both the positive electrode 11 and the negative electrode 12, and at least a part of the base of each electrode lead is covered with the insulating tape 40.
  • the insulating tape 40 may be attached only to the positive electrode 11, and a conventionally known insulating tape not having a heat conductive layer 43 described later may be attached to the negative electrode 12. Further, instead of the insulating tape 40, an insulating tape 50 described later may be used.
  • the insulating tape 40 has, for example, a rectangular shape (strip shape) in a front view wider than the electrode leads.
  • the insulating tape 40 is preferably attached to cover the entire base of the electrode lead. In the example shown in FIG. 2, the entire base of the positive electrode lead 19 and the entire exposed portion 32 are covered with the insulating tape 40.
  • a part of the insulating tape 40 is attached also on the positive electrode mixture layer 31 formed on both sides of the exposed portion 32.
  • the insulating tape 40 is preferably further adhered to the other exposed portion 32 formed on the opposite side of the exposed portion 32 to which the positive electrode lead 19 is welded. That is, the insulating tape 40 is adhered to both surfaces of the positive electrode 11 so as to cover the exposed portions 32.
  • the insulating tape 40 may be attached to the base of the extension of the positive electrode lead 19 beyond the range of the positive electrode current collector 30.
  • the base portion of the extended portion of the positive electrode lead 19 faces the negative electrode 12 through the separator 13, so there is a concern that the internal short circuit may occur due to the melting of the separator 13. Therefore, it is preferable that the insulating tape 40 be stuck also to the said root part.
  • the insulating tape 40 is attached to the negative electrode lead 20 and the exposed portion 37 as in the case of the positive electrode 11, but in the example shown in FIG. 2, the entire base of the negative electrode lead 20 and a part of the exposed portion 37 It is covered and stuck.
  • FIG. 3 is a view showing the electrode 60 to which the insulating tape 40 is attached, where (a) is a front view and (b) is a cross-sectional view taken along line AA in (a).
  • the electrode 60 may be either a positive electrode or a negative electrode.
  • the insulating tape 40 may be attached to the electrode 60 along the boundary between the mixture layer 62 and the exposed portion 63 of the current collector 61 so as to cover the boundary. Good.
  • the insulating tape 40 is attached across the end of the mixture layer 62 and the exposed portion 63.
  • the insulating tape 40 may be attached to only one side of the electrode 60 or may be attached to both sides.
  • FIG. 4 is a cross-sectional view of an insulating tape 40 which is an example of the embodiment.
  • the insulating tape 40 is interposed between the base layer 41 made of an insulating organic material, the adhesive layer 42, and the base layer 41 and the adhesive layer 42,
  • a thermally conductive layer 43 containing at least one of a carbon-based filler and a metal filler is provided as the thermally conductive filler.
  • the content of the thermally conductive filler is preferably 25% by volume or more with respect to the volume of the thermally conductive layer 43.
  • the insulating tape 40 suppresses an internal short circuit without affecting the battery performance.
  • the thickness of the insulating tape 40 is, for example, 10 to 60 ⁇ m, and preferably 15 to 40 ⁇ m.
  • the thickness of the insulating tape 40 and each layer can be measured by cross-sectional observation using a scanning electron microscope (SEM).
  • SEM scanning electron microscope
  • the insulating tape 40 may have a layer structure of four or more layers.
  • the base material layer 41 is not limited to a single layer structure, and may be constituted by two or more layers of the same or different laminated films.
  • the base layer 41 is preferably substantially made of only an organic material.
  • the ratio of the organic material to the constituent material of the base material layer 41 is, for example, 90% by weight or more, preferably 95% by weight or more, or 100% by weight.
  • the main component of the organic material is preferably a resin which is excellent in insulation, electrolyte resistance, heat resistance, puncture strength and the like.
  • the thickness of the base layer 41 is, for example, 5 to 50 ⁇ m, preferably 15 to 35 ⁇ m.
  • polyesters such as a polyethylene terephthalate (PET), a polypropylene (PP), a polyimide (PI), polyphenylene sulfide (PPS), a polyether imide (PEI), a polyamide etc.
  • PET polyethylene terephthalate
  • PP polypropylene
  • PI polyimide
  • PPS polyphenylene sulfide
  • PEI polyether imide
  • a polyamide a polyamide
  • One of these may be used alone, or two or more of these may be used in combination.
  • polyimide having high mechanical strength (piercing strength) is particularly preferable.
  • a resin film made of polyimide can be used for example.
  • the adhesive layer 42 is a layer for providing the insulating tape 40 with adhesiveness to the positive electrode lead 19.
  • the adhesive layer 42 is formed, for example, by applying an adhesive on one surface of the base layer 41 on which the heat conductive layer 43 is formed.
  • the adhesive layer 42 is preferably configured using an adhesive (resin) that is excellent in insulation properties, electrolytic solution resistance, and the like.
  • the adhesive constituting the adhesive layer 42 may be a hot melt type which exhibits adhesiveness by heating or a thermosetting type which cures by heating, but from the viewpoint of productivity etc. It is preferable to have.
  • An example of the adhesive constituting the adhesive layer 42 is an acrylic adhesive or a synthetic rubber adhesive.
  • the adhesive layer 42 has a thickness of, for example, 3 to 20 ⁇ m.
  • the heat conductive layer 43 is a layer containing at least one of a carbon-based filler and a metal filler as a heat conductive filler as described above.
  • the thermally conductive layer 43 is a composite layer composed of a thermally conductive filler and an organic material, and has a layer structure in which the thermally conductive filler is dispersed in a matrix made of an organic material, or a thermally conductive filler is an organic material. Have a layered structure formed by bonding.
  • the heat conductive layer 43 is formed, for example, by dispersing a heat conductive filler in an organic material, applying it to the surface of the resin film constituting the base layer 41, and curing the coating film. Alternatively, it is formed by dispersing a thermally conductive filler in a solution of an organic material, applying the solution to the surface of a resin film, evaporating off the solvent, and drying the coating.
  • the preferred thickness of the heat conduction layer 43 is 1 to 10 ⁇ m. In this case, it becomes easy to secure sufficient heat dissipation and heat resistance.
  • the content of the thermally conductive filler is preferably 25 to 70% by volume, more preferably 25 to 50% by volume, with respect to the volume of the thermally conductive layer 43. If the content of the thermally conductive filler is within the above range, a good heat transfer path is formed, and the thermally conductive layer 43 excellent in thermal conductivity is formed.
  • the base layer 41 is provided, and the thermally conductive layer 43 is interposed between the base layer 41 and the adhesive layer 42, whereby the amount of the thermally conductive filler added to the thermally conductive layer 43 is increased. However, good stab strength can be secured.
  • a suitable carbonaceous filler which constitutes heat conduction layer 43 it is at least one sort chosen from diamond, graphite, and carbon fiber. These have high thermal conductivity and improve the heat dissipation function of the thermal conductive layer 43. When a particulate carbon-based filler is used, the average particle size is preferably 1 ⁇ m or less.
  • the heat conduction layer 43 may contain one or more carbon-based fillers, and may contain metal fillers in addition to the carbon-based fillers.
  • Preferred metal fillers are composed of metals based on at least one selected from aluminum, titanium, silicon, magnesium, and stainless steel. These have good chemical stability in the electrolyte and are also excellent in thermal conductivity.
  • the main component means a component having the largest weight among the metal components constituting the metal filler (the same applies to metal foil described later).
  • the metal filler may be made of, for example, an alloy such as an aluminum alloy, or may be made of only one metal such as aluminum.
  • the shape of the metal filler is not particularly limited, and may be granular, needle-like, plate-like or fibrous.
  • the heat conduction layer 43 may contain one or more metal fillers.
  • the organic material (resin) constituting the heat conduction layer 43 is excellent in insulation, electrolyte resistance, etc., and has good adhesion to the base material layer 41.
  • suitable resins include acrylic resins, epoxy resins, urethane resins, and fluorine resins such as PVdF. One of these may be used alone, or two or more of these may be used in combination.
  • FIG. 5 is a cross-sectional view of an insulating tape 50 which is another example of the embodiment.
  • the same components as those of the insulating tape 40 shown in FIG. 4 are denoted by the same reference numerals.
  • the insulating tape 50 includes a base layer 41, an adhesive layer 42, and a thermally conductive layer 53 made of metal foil interposed between the base layer 41 and the adhesive layer 42.
  • the configuration of the insulating tape 50 differs from the configuration of the insulating tape 40 in that the heat conductive layer 53 is provided instead of the heat conductive layer 43. Even when the insulating tape 50 is used, the same function and effect as the case where the insulating tape 40 is used can be obtained.
  • the preferred thickness of the heat conduction layer 53 is 1 to 10 ⁇ m.
  • the heat conduction layer 53 is formed using a metal foil having a thickness of 1 to 10 ⁇ m.
  • the insulating tape 50 is formed, for example, by applying a solution of the resin forming the base layer 41 on the metal foil forming the heat conductive layer 53 and drying the coating film.
  • the base layer 41 may be formed by applying an uncured resin on a metal foil and curing the coating.
  • the metal foil constituting the heat conduction layer 53 and the resin film constituting the base layer 41 may be bonded using an adhesive.
  • a preferred metal foil constituting the heat conduction layer 53 is composed of a metal whose main component is at least one selected from aluminum, titanium, silicon, magnesium and stainless steel. These have good chemical stability in the electrolyte and are also excellent in thermal conductivity.
  • the metal foil may be made of, for example, an alloy foil such as an aluminum alloy, or may be made of only one kind of metal foil such as aluminum.
  • Example 1 [Create positive electrode] 100 parts by weight of lithium nickel cobalt aluminum complex oxide represented by LiNi 0.88 Co 0.09 Al 0.03 O 2 as a positive electrode active material, 1 part by weight of acetylene black (AB), and 1 part by weight of polyvinylidene fluoride (PVdF) And a proper amount of N-methyl-2-pyrrolidone (NMP) to prepare a positive electrode mixture slurry. Next, the positive electrode mixture slurry was applied to both sides of a positive electrode current collector made of aluminum foil, and the coating was dried.
  • LiNi 0.88 Co 0.09 Al 0.03 O 2 a positive electrode active material
  • PVdF polyvinylidene fluoride
  • NMP N-methyl-2-pyrrolidone
  • the current collector on which the coating film was formed was compressed using a roller, and then cut into a predetermined electrode size to prepare a positive electrode in which a positive electrode mixture layer was formed on both sides of the positive electrode current collector.
  • An exposed portion in which the mixture layer was not formed at the central portion in the longitudinal direction of the positive electrode and the current collector surface was exposed was provided, and a positive electrode lead made of aluminum was ultrasonically welded to the exposed portion.
  • An insulating tape was attached to the positive electrode so as to cover the base of the positive electrode lead, the base of the extension, and each exposed portion.
  • the layer configuration of the insulating tape is as follows.
  • Base material layer 25 ⁇ m thick polyimide film
  • Adhesive layer 7 ⁇ m thick acrylic adhesive layer
  • Thermal conductive layer 1 ⁇ m thick composite layer composed of 25 volume% of diamond filler and 75 volume% of acrylic resin Creation of] Mix 98 parts by weight of graphite powder, 1 part by weight of sodium carboxymethylcellulose (CMC-Na), and 1 part by weight of styrene-butadiene rubber (SBR), add an appropriate amount of water, and mix the negative electrode slurry Prepared. Next, the negative electrode mixture slurry was applied to both sides of a negative electrode current collector made of copper foil, and the coating was dried.
  • CMC-Na sodium carboxymethylcellulose
  • SBR styrene-butadiene rubber
  • the current collector on which the coating film was formed was compressed using a roller, and then cut into a predetermined electrode size to prepare a negative electrode in which a negative electrode mixture layer was formed on both sides of the negative electrode current collector.
  • An exposed portion in which the mixture layer was not formed at one longitudinal end portion (portion to be the winding outer end portion) of the negative electrode and the current collector surface was exposed was provided, and a nickel negative electrode lead was ultrasonically welded to the exposed portion.
  • the above-mentioned insulating tape was stuck to the negative electrode so as to cover the base of the negative electrode lead, the root portion of the extending portion, and each exposed portion.
  • Ethylene carbonate (EC), ethyl methyl carbonate (EMC) and dimethyl carbonate (DMC) were mixed in a volume ratio of 3: 3: 4.
  • LiPF 6 was dissolved at a concentration of 1 mol / L to prepare a non-aqueous electrolyte.
  • a winding type electrode body is formed by spirally winding the positive electrode and the negative electrode through a separator made of a porous film made of polyethylene having a heat resistant layer in which fillers of polyamide and alumina are dispersed on one side. did.
  • the extension of the positive electrode lead is used as a filter of the sealing body and the extension of the negative electrode lead is Each was welded to the bottom inner surface. Then, the non-aqueous electrolyte was injected into the case main body, and the opening of the case main body was closed with a sealing member, to prepare a 18650 type cylindrical battery.
  • Example 2 A cylindrical battery was produced in the same manner as in Example 1 except that the heat conduction layer of the insulating tape used in Example 1 was as shown in Table 1.
  • Example 7 A cylindrical battery was produced in the same manner as in Example 1, except that the insulating tape used in Example 1 was replaced by an insulating tape having the following layer structure.
  • Example 8 A cylindrical battery was produced in the same manner as in Example 7 except that the heat conduction layer of the insulating tape used in Example 7 was changed to that shown in Table 1.
  • Comparative Example 1 A cylindrical battery was produced in the same manner as in Example 1, except that the insulating tape used in Example 1 was replaced by an insulating tape having the following layer structure.
  • the amount of water contained in the insulating tape used for each battery was measured using the Karl Fischer method.
  • the heating temperature was 150.degree.
  • the battery temperature at the time of the foreign matter short circuit was lower than that of the battery of the comparative example.
  • the heat generated in the short circuit can be diffused quickly by the function of the heat conduction layer of the insulating tape, which leads to the suppression of the rise of the battery temperature. That is, the heat dissipating function of the heat conduction layer can suppress the deformation and deterioration of the base material layer and the separator, and can suppress the increase in battery temperature due to the expansion of the short circuit portion.

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Abstract

This secondary battery is provided with: an electrode body which is obtained by laminating a positive electrode and a negative electrode, with a separator being interposed therebetween; an electrolyte; and an insulating tape which is bonded to at least one of the positive electrode and the negative electrode. The insulating tape comprises: a base material layer which is configured from an insulating organic material; an adhesive layer; and a heat conduction layer which is interposed between the base material layer and the adhesive layer and contains, as a heat conductive filler, at least one of a carbon-based filler and a metal filler.

Description

二次電池Secondary battery
　本開示は、二次電池に関する。 The present disclosure relates to a secondary battery.
　従来から、絶縁テープを用いて正極あるいは負極の絶縁性を向上させたリチウム二次電池が提案されている。 Conventionally, a lithium secondary battery has been proposed in which the insulation properties of the positive electrode or the negative electrode are improved by using an insulating tape.
　例えば、特許文献１には、有機材料を主体とする有機材料層と、有機材料と無機材料とを含む複合材料層とを含む多層構造の絶縁テープを備えた非水電解質二次電池が開示されている。 For example, Patent Document 1 discloses a non-aqueous electrolyte secondary battery including an insulating tape having a multilayer structure including an organic material layer mainly composed of an organic material and a composite material layer containing an organic material and an inorganic material. ing.
国際公開第２０１６／１２１３３９号International Publication No. 2016/121339
　特許文献１に開示された技術によれば、例えば導電性の異物に起因した内部短絡による発熱を抑制することができる。しかし、酸化物、窒化物に代表される無機材料は表面に吸着水を含むため、無機材料を含有する絶縁テープを用いた場合、この水分が電池特性に悪影響を与える可能性がある。また、万が一、導電性の異物が絶縁テープを突き破り内部短絡が発生した場合に、短絡箇所の拡大を防ぎ、電池温度の上昇を抑えることは重要な課題である。 According to the technique disclosed in Patent Document 1, for example, heat generation due to internal short circuit caused by conductive foreign matter can be suppressed. However, since inorganic materials represented by oxides and nitrides contain adsorbed water on the surface, when using an insulating tape containing an inorganic material, this moisture may adversely affect battery characteristics. In the case where an electrically conductive foreign material breaks through the insulating tape and an internal short circuit occurs, it is an important task to prevent the expansion of the short circuit location and to suppress the rise in the battery temperature.
　本開示の一態様である二次電池は、正極と負極がセパレータを介して積層されてなる電極体を備えた二次電池において、前記正極および前記負極は、集電体と、前記集電体上に形成された合材層と、前記集電体の表面が露出した露出部に接続された電極リードとを有し、前記正極および前記負極の少なくとも一方において、前記電極リードおよび前記露出部の少なくとも一方に貼着された絶縁テープを備え、前記絶縁テープは、絶縁性の有機材料で構成された基材層と、接着剤層と、前記基材層と前記接着剤層との間に介在し、熱伝導性フィラーとして、炭素系フィラーおよび金属フィラーの少なくとも一方を含有する熱伝導層とを有することを特徴とする。 The secondary battery according to one aspect of the present disclosure is a secondary battery including an electrode body in which a positive electrode and a negative electrode are stacked via a separator, wherein the positive electrode and the negative electrode are a current collector, and the current collector. An electrode lead connected to an exposed portion where the surface of the current collector is exposed, and at least one of the positive electrode and the negative electrode, the electrode lead and the exposed portion The insulating tape includes an insulating tape attached to at least one side, and the insulating tape is interposed between a substrate layer made of an insulating organic material, an adhesive layer, the substrate layer, and the adhesive layer. And a thermally conductive layer containing at least one of a carbonaceous filler and a metallic filler as the thermally conductive filler.
　本開示の他の一態様である二次電池は、正極と負極がセパレータを介して積層されてなる電極体を備えた二次電池において、前記正極および前記負極は、集電体と、前記集電体上に形成された合材層と、前記集電体の表面が露出した露出部に接続された電極リードとを有し、前記正極および前記負極の少なくとも一方において、前記電極リードおよび前記露出部の少なくとも一方に貼着された絶縁テープを備え、前記絶縁テープは、絶縁性の有機材料で構成された基材層と、接着剤層と、前記基材層と前記接着剤層との間に介在する金属箔からなる熱伝導層とを有することを特徴とする。 The secondary battery according to another aspect of the present disclosure is a secondary battery including an electrode body in which a positive electrode and a negative electrode are stacked via a separator, wherein the positive electrode and the negative electrode are a current collector, and the collector is A composite material layer formed on a current collector, and an electrode lead connected to an exposed portion where the surface of the current collector is exposed, wherein at least one of the positive electrode and the negative electrode, the electrode lead and the exposure Between the base material layer made of an insulating organic material, an adhesive layer, the base material layer, and the adhesive layer. And a thermally conductive layer made of metal foil.
　本開示に係る二次電池によれば、良好な電池性能を維持しながら内部短絡を抑制できる。また、万が一、内部短絡が発生したとしても、電池温度の上昇を抑えることができる。 According to the secondary battery of the present disclosure, internal short circuit can be suppressed while maintaining good battery performance. Further, even if an internal short circuit occurs, the rise in battery temperature can be suppressed.
実施形態の一例である二次電池の断面図である。It is sectional drawing of the secondary battery which is an example of embodiment. 実施形態の一例である電極体を構成する正極および負極の正面図である。It is a front view of the positive electrode which comprises the electrode body which is an example of embodiment, and a negative electrode. 実施形態の他の一例である電極を示す図である。It is a figure which shows the electrode which is another example of embodiment. 実施形態の一例である絶縁テープの断面図である。It is sectional drawing of the insulating tape which is an example of embodiment. 実施形態の他の一例である絶縁テープの断面図である。It is sectional drawing of the insulating tape which is another example of embodiment.
　本開示に係る二次電池は、炭素系フィラーおよび金属フィラーの少なくとも一方を含有する熱伝導層または金属箔からなる熱伝導層を有する絶縁テープを用いることで、良好な電池性能を維持しながら内部短絡による発熱を高度に抑制できる。炭素系フィラー、金属フィラー、および金属箔は、水分を吸着し難いため、当該絶縁テープは電池内の水分量を増加させない。このため、本開示に係る二次電池では、水分の浸入による不具合が起こり難く、良好な電池性能が維持される。なお、水分が電池性能に与える影響としては、充電状態で保存したときの放電容量の低下が挙げられる。 The secondary battery according to the present disclosure uses a thermally conductive layer containing at least one of a carbon-based filler and a metal filler or an insulating tape having a thermally conductive layer composed of a metal foil to maintain good battery performance while maintaining good battery performance. The heat generation due to the short circuit can be highly suppressed. Since the carbon-based filler, the metal filler, and the metal foil hardly adsorb moisture, the insulating tape does not increase the amount of moisture in the battery. For this reason, in the secondary battery according to the present disclosure, a failure due to the intrusion of moisture is unlikely to occur, and good battery performance is maintained. In addition, the fall of the discharge capacity when it preserve | saves in charge condition is mentioned as an influence which water has on battery performance.
　また、炭素系フィラー、金属フィラー、および金属箔は、熱伝導性が高いため、万が一、導電性の異物が絶縁テープを突き破り内部短絡が発生したとしても、短絡により発生する熱を速やかに放熱できる。これにより、絶縁テープ（基材層）およびセパレータの変形変質を抑制でき、短絡箇所の拡大による電池温度の上昇を抑えることができる。 In addition, since carbon fillers, metal fillers and metal foils have high thermal conductivity, even if conductive foreign matter breaks through the insulating tape and an internal short circuit occurs, the heat generated by the short circuit can be dissipated quickly. . As a result, deformation and deterioration of the insulating tape (base material layer) and the separator can be suppressed, and an increase in battery temperature due to the expansion of the short circuit portion can be suppressed.
　以下、実施形態の一例について詳細に説明する。以下では、巻回構造の電極体１４が円筒形の電池ケースに収容された円筒形電池を例示するが、電池ケースは、例えば角形の金属製ケース（角形電池）、樹脂フィルムによって構成される樹脂製ケース（ラミネート電池）などであってもよい。 Hereinafter, an example of the embodiment will be described in detail. In the following, a cylindrical battery in which the wound electrode assembly 14 is housed in a cylindrical battery case is exemplified. However, the battery case is, for example, a resin made of a square metal case (square battery) and a resin film. It may be a case (laminated battery) or the like.
　図１は、実施形態の一例である二次電池１０の断面図である。図１に例示するように、二次電池１０は、電極体１４と、電解質（図示せず）と、電極体１４および電解質を収容する電池ケースとを備える。二次電池１０の好適な一例は、リチウムイオン電池である。電極体１４は、正極１１と負極１２がセパレータ１３を介して巻回された巻回構造を有する。電池ケースは、有底筒状のケース本体１５と、当該本体の開口部を塞ぐ封口体１６とで構成されている。 FIG. 1 is a cross-sectional view of a secondary battery 10 which is an example of the embodiment. As illustrated in FIG. 1, the secondary battery 10 includes an electrode body 14, an electrolyte (not shown), and a battery case that accommodates the electrode body 14 and the electrolyte. A preferred example of the secondary battery 10 is a lithium ion battery. The electrode body 14 has a wound structure in which the positive electrode 11 and the negative electrode 12 are wound via the separator 13. The battery case is configured of a bottomed cylindrical case main body 15 and a sealing body 16 that closes the opening of the main body.
　電解質は、溶媒と、溶媒に溶解した電解質塩とを含む。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の非水溶媒や水を用いてもよい。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を含有していてもよい。なお、電解質は液体電解質に限定されず、ゲル状ポリマー等を用いた固体電解質であってもよい。電解質塩には、例えばＬｉＰＦ6等のリチウム塩が使用される。 The electrolyte comprises a solvent and an electrolyte salt dissolved in the solvent. As the solvent, for example, nonaqueous solvents such as esters, ethers, nitriles, amides, and mixed solvents of two or more of them, and water may be used. The solvent may contain a halogen substitute wherein at least a part of hydrogen of these solvents is substituted with a halogen atom such as fluorine. The electrolyte is not limited to the liquid electrolyte, and may be a solid electrolyte using a gel polymer or the like. For the electrolyte salt, for example, a lithium salt such as LiPF 6 is used.
　二次電池１０は、電極体１４の上下にそれぞれ配置された絶縁板１７，１８を備える。図１に示す例では、正極リード１９が絶縁板１７の貫通孔を通って封口体１６側に延び、負極リード２０が絶縁板１８の外側を通ってケース本体１５の底部側に延びている。正極リード１９は封口体１６の底板であるフィルタ２２の下面に溶接等で接続され、フィルタ２２と電気的に接続された封口体１６の天板であるキャップ２６が正極端子となる。負極リード２０はケース本体１５の底部内面に溶接等で接続され、ケース本体１５が負極端子となる。 The secondary battery 10 includes insulating plates 17 and 18 disposed above and below the electrode body 14. In the example shown in FIG. 1, the positive electrode lead 19 extends through the through hole of the insulating plate 17 toward the sealing body 16, and the negative electrode lead 20 extends through the outside of the insulating plate 18 toward the bottom of the case body 15. The positive electrode lead 19 is connected to the lower surface of the filter 22 which is a bottom plate of the sealing member 16 by welding or the like, and a cap 26 which is a top plate of the sealing member 16 electrically connected to the filter 22 serves as a positive electrode terminal. The negative electrode lead 20 is connected to the inner surface of the bottom of the case main body 15 by welding or the like, and the case main body 15 becomes a negative electrode terminal.
　ケース本体１５は、例えば有底円筒形状の金属製容器である。ケース本体１５と封口体１６との間にはガスケット２７が設けられ、電池ケース内部の密閉性が確保される。ケース本体１５は、例えば側面部を外側からプレスして形成された、封口体１６を支持する張り出し部２１を有する。張り出し部２１は、ケース本体１５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１６を支持する。 The case main body 15 is, for example, a metal container with a bottomed cylindrical shape. A gasket 27 is provided between the case main body 15 and the sealing body 16 to ensure the airtightness inside the battery case. The case main body 15 has an overhanging portion 21 for supporting the sealing body 16 which is formed, for example, by pressing the side surface portion from the outside. The projecting portion 21 is preferably formed in an annular shape along the circumferential direction of the case main body 15, and the sealing member 16 is supported on the upper surface thereof.
　封口体１６は、電極体１４側から順に、フィルタ２２、下弁体２３、絶縁部材２４、上弁体２５、およびキャップ２６が積層された構造を有する。封口体１６を構成する各部材は、例えば円板形状またはリング形状を有し、絶縁部材２４を除く各部材は互いに電気的に接続されている。下弁体２３と上弁体２５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２４が介在している。下弁体２３には通気孔が設けられているため、異常発熱で電池の内圧が上昇すると、上弁体２５がキャップ２６側に膨れて下弁体２３から離れることにより両者の電気的接続が遮断される。さらに内圧が上昇すると、上弁体２５が破断し、キャップ２６の開口部からガスが排出される。 The sealing body 16 has a structure in which the filter 22, the lower valve body 23, the insulating member 24, the upper valve body 25, and the cap 26 are sequentially stacked from the electrode body 14 side. Each member which comprises the sealing body 16 has disk shape or ring shape, for example, and each member except the insulation member 24 is electrically connected mutually. The lower valve body 23 and the upper valve body 25 are connected to each other at their central portions, and an insulating member 24 is interposed between the respective peripheral edge portions. Since the lower valve body 23 is provided with a vent, if the internal pressure of the battery rises due to abnormal heat generation, the upper valve body 25 bulges to the cap 26 side and separates from the lower valve body 23 so that the electrical connection between them is achieved. It is cut off. When the internal pressure further increases, the upper valve body 25 is broken, and the gas is discharged from the opening of the cap 26.
　以下、図２～図５を参照しながら、正極１１および負極１２について、特に電極リードに貼着される絶縁テープ４０，５０について詳説する。図２は、電極体１４を構成する正極１１および負極１２の正面図であって、紙面右側が巻芯側である。 Hereinafter, with reference to FIGS. 2 to 5, the positive electrodes 11 and the negative electrodes 12, particularly, the insulating tapes 40 and 50 attached to the electrode leads will be described in detail. FIG. 2 is a front view of the positive electrode 11 and the negative electrode 12 constituting the electrode assembly 14, and the right side of the drawing is the core side.
　図２に例示するように、電極体１４では、負極１２上でのリチウムの析出を防止するため、負極１２が正極１１よりも大きく形成され、負極１２の負極集電体３５には正極１１の正極集電体３０よりも長く幅が広い集電体が用いられる。そして、少なくとも正極１１の正極合材層３１が形成された部分は、セパレータ１３を介して負極１２の負極合材層３６が形成された部分に対向配置される。 As illustrated in FIG. 2, in the electrode body 14, the negative electrode 12 is formed larger than the positive electrode 11 in order to prevent deposition of lithium on the negative electrode 12, and the negative electrode current collector 35 of the negative electrode 12 A current collector longer in width and wider than the positive electrode current collector 30 is used. Then, at least a portion where the positive electrode mixture layer 31 of the positive electrode 11 is formed is opposed to a portion where the negative electrode mixture layer 36 of the negative electrode 12 is formed via the separator 13.
　正極１１は、正極集電体３０と、正極集電体３０上に形成された正極合材層３１と、正極集電体３０の表面が露出した露出部３２に接続された正極リード１９とを有する。本実施形態では、帯状の正極集電体３０の両面に正極合材層３１が形成されている。正極集電体３０には、例えばアルミニウムなどの金属の箔、当該金属を表層に配置したフィルム等が用いられる。正極集電体３０の厚みは、例えば５μｍ～３０μｍである。 The positive electrode 11 includes a positive electrode current collector 30, a positive electrode mixture layer 31 formed on the positive electrode current collector 30, and a positive electrode lead 19 connected to the exposed portion 32 where the surface of the positive electrode current collector 30 is exposed. Have. In the present embodiment, the positive electrode mixture layer 31 is formed on both surfaces of the strip-shaped positive electrode current collector 30. For the positive electrode current collector 30, for example, a foil of a metal such as aluminum, a film in which the metal is disposed on the surface, or the like is used. The thickness of the positive electrode current collector 30 is, for example, 5 μm to 30 μm.
　正極合材層３１は、正極集電体３０の両面において、露出部３２を除く全域に形成されることが好適である。正極合材層３１は、正極活物質、カーボンブラック、アセチレンブラック等の導電材、およびポリフッ化ビニリデン（ＰＶｄＦ）等バインダを含む。正極活物質としては、Ｃｏ、Ｍｎ、Ｎｉ、Ａｌ等の金属元素を含有するリチウム金属複合酸化物が例示できる。正極１１は、正極活物質、導電材、バインダ、およびＮ－メチル－２－ピロリドン（ＮＭＰ）等の分散媒を含む正極合材スラリーを正極集電体３０の両面に塗布し、塗膜を圧縮することにより作成できる。 The positive electrode mixture layer 31 is preferably formed on the entire surface of the positive electrode current collector 30 except for the exposed portion 32. The positive electrode mixture layer 31 contains a positive electrode active material, a conductive material such as carbon black or acetylene black, and a binder such as polyvinylidene fluoride (PVdF). As a positive electrode active material, lithium metal complex oxide containing metallic elements, such as Co, Mn, Ni, and Al, can be illustrated. The positive electrode 11 applies a positive electrode mixture slurry containing a positive electrode active material, a conductive material, a binder, and a dispersion medium such as N-methyl-2-pyrrolidone (NMP) on both sides of the positive electrode current collector 30, and the coating is compressed. Can be created by
　露出部３２は、正極集電体３０の表面が正極合材層３１に覆われていない部分である。露出部３２は、例えば正極１１の全幅にわたって、正極リード１９よりも幅広に形成される。露出部３２は、正極１１の厚み方向に重なるように正極１１の両面に設けられることが好適である。図２に示す例では、正極１１の長手方向中央部において、露出部３２が正極１１の片側に１つずつ設けられている。 The exposed portion 32 is a portion in which the surface of the positive electrode current collector 30 is not covered by the positive electrode mixture layer 31. The exposed portion 32 is formed wider than the positive electrode lead 19, for example, across the entire width of the positive electrode 11. The exposed portions 32 are preferably provided on both sides of the positive electrode 11 so as to overlap in the thickness direction of the positive electrode 11. In the example shown in FIG. 2, one exposed portion 32 is provided on one side of the positive electrode 11 at the central portion in the longitudinal direction of the positive electrode 11.
　負極１２は、負極集電体３５と、負極集電体３５上に形成された負極合材層３６と、負極集電体３５の表面が露出した露出部３７に接続された負極リード２０とを有する。本実施形態では、帯状の負極集電体３５の両面に負極合材層３６が形成されている。負極集電体３５には、例えば銅などの金属の箔、当該金属を表層に配置したフィルム等が用いられる。負極集電体３５の厚みは、例えば５μｍ～３０μｍである。 The negative electrode 12 includes a negative electrode current collector 35, a negative electrode mixture layer 36 formed on the negative electrode current collector 35, and a negative electrode lead 20 connected to the exposed portion 37 where the surface of the negative electrode current collector 35 is exposed. Have. In the present embodiment, the negative electrode mixture layer 36 is formed on both sides of the strip-like negative electrode current collector 35. For the negative electrode current collector 35, for example, a foil of a metal such as copper, a film in which the metal is disposed on the surface, or the like is used. The thickness of the negative electrode current collector 35 is, for example, 5 μm to 30 μm.
　負極合材層３６は、負極集電体３５の両面において、露出部３７を除く全域に形成されることが好適である。負極合材層３６は、負極活物質、およびスチレン－ブタジエンゴム（ＳＢＲ）等のバインダを含む。負極活物質としては、リチウムイオンを可逆的に吸蔵、放出できるものであれば特に限定されず、例えば天然黒鉛、人造黒鉛等の炭素材料、Ｓｉ、Ｓｎ等のリチウムと合金化する金属、またはこれらを含む合金、複合酸化物などを用いることができる。負極１２は、負極活物質、バインダ、および水等を含む負極合材スラリーを負極集電体３５の両面に塗布し、塗膜を圧縮することにより作成できる。 The negative electrode mixture layer 36 is preferably formed on the entire surface of the negative electrode current collector 35 except for the exposed portion 37. The negative electrode mixture layer 36 contains a negative electrode active material and a binder such as styrene-butadiene rubber (SBR). The negative electrode active material is not particularly limited as long as it can occlude and release lithium ions reversibly, for example, carbon materials such as natural graphite and artificial graphite, metals alloyed with lithium such as Si and Sn, or these Alloys, complex oxides, etc. can be used. The negative electrode 12 can be prepared by applying a negative electrode mixture slurry containing a negative electrode active material, a binder, water, and the like on both sides of the negative electrode current collector 35 and compressing the coating film.
　露出部３７は、負極集電体３５の表面が負極合材層３６に覆われていない部分である。露出部３７は、例えば負極１２の全幅にわたって、負極リード２０よりも幅広に形成される。図２に示す例では、負極１２の長手方向一端部であって電極体１４の巻外側に位置する端部に、露出部３７が負極１２の片側に１つずつ設けられている。 The exposed portion 37 is a portion where the surface of the negative electrode current collector 35 is not covered by the negative electrode mixture layer 36. The exposed portion 37 is formed wider than the negative electrode lead 20, for example, across the entire width of the negative electrode 12. In the example shown in FIG. 2, one exposed portion 37 is provided on one side of the negative electrode 12 at one end in the longitudinal direction of the negative electrode 12 and located on the winding outer side of the electrode body 14.
　なお、露出部３２，３７の位置は特に限定されない。例えば、露出部３７は電極体１４の巻芯側に位置する負極１２の端部（負極１２の長手方向他端部）に設けられていてもよく、負極１２の長手方向両端部に設けられていてもよい。 The positions of the exposed portions 32 and 37 are not particularly limited. For example, the exposed portion 37 may be provided at the end of the negative electrode 12 (the other end in the longitudinal direction of the negative electrode 12) located on the winding core side of the electrode body 14 and provided at both longitudinal ends of the negative electrode 12 May be
　正極リード１９および負極リード２０は、集電体および合材層よりも厚みのある帯状の導電部材である。リードの厚みは、例えば５０μｍ～５００μｍである。各リードの構成材料は特に限定されないが、正極リード１９はアルミニウムを主成分とする金属によって、負極リード２０はニッケルまたは銅を主成分とする金属によって、それぞれ構成されることが好ましい。なお、リードの数、配置等は特に限定されない。 The positive electrode lead 19 and the negative electrode lead 20 are strip-like conductive members that are thicker than the current collector and the mixture layer. The thickness of the lead is, for example, 50 μm to 500 μm. The constituent material of each lead is not particularly limited, but it is preferable that the positive electrode lead 19 be made of a metal whose main component is aluminum, and the negative electrode lead 20 be a metal whose main component is nickel or copper. The number, arrangement, and the like of the leads are not particularly limited.
　二次電池１０は、正極１１および負極１２の少なくとも一方において、電極リードおよび露出部の少なくとも一方に貼着された絶縁テープ４０を備える。絶縁テープ４０は、電極リードのうち、集電体上に位置する部分（以下、「基部」という場合がある）の少なくとも一部に貼着されることが好ましい。電極リードの基部は、一般的に露出部３２，３７に溶接されるが、その全体が溶接されていなくてもよい。なお、正極リード１９の一部は正極集電体３０の上端から延出して封口体１６に接続され、負極リード２０の一部は負極集電体３５の下端から延出してケース本体１５の底部内面に接続される（以下、当該一部を「延出部」という場合がある）。 The secondary battery 10 includes an insulating tape 40 attached to at least one of the electrode lead and the exposed portion in at least one of the positive electrode 11 and the negative electrode 12. The insulating tape 40 is preferably attached to at least a part of a portion (hereinafter, may be referred to as a “base”) located on the current collector among the electrode leads. The base of the electrode lead is generally welded to the exposed portions 32, 37, but the whole may not be welded. A part of the positive electrode lead 19 extends from the upper end of the positive electrode current collector 30 and is connected to the sealing member 16, and a part of the negative electrode lead 20 extends from the lower end of the negative electrode current collector 35 and the bottom of the case main body 15 It is connected to the inner surface (hereinafter, a part of the part may be referred to as an “extension part”).
　図２に示す例では、正極１１および負極１２の両方に絶縁テープ４０が貼着され、各電極リードの基部の少なくとも一部が絶縁テープ４０で覆われている。上述の通り、電極リードが接続される部分は、電極の他の部分と比べて極板間の圧力が高くなり易く、導電性の異物に起因した内部短絡が発生し易いが、絶縁テープ４０を設けることで、かかる内部短絡を抑制できる。なお、絶縁テープ４０は正極１１のみに貼着されていてもよく、負極１２には後述の熱伝導層４３を有さない従来公知の絶縁テープが貼着されてもよい。また、絶縁テープ４０の代わりに、後述の絶縁テープ５０を用いてもよい。 In the example shown in FIG. 2, the insulating tape 40 is attached to both the positive electrode 11 and the negative electrode 12, and at least a part of the base of each electrode lead is covered with the insulating tape 40. As described above, in the portion where the electrode lead is connected, the pressure between the electrode plates tends to be high compared to the other portions of the electrode, and an internal short circuit caused by conductive foreign matter is likely to occur. Such provision can suppress such internal short circuit. The insulating tape 40 may be attached only to the positive electrode 11, and a conventionally known insulating tape not having a heat conductive layer 43 described later may be attached to the negative electrode 12. Further, instead of the insulating tape 40, an insulating tape 50 described later may be used.
　絶縁テープ４０は、例えば電極リードよりも幅広の正面視矩形形状（短冊状）を有する。絶縁テープ４０は、電極リードの基部の全体を覆って貼着されることが好ましい。図２に示す例では、正極リード１９の基部の全体、および露出部３２の全体が絶縁テープ４０に覆われている。また、絶縁テープ４０の一部は、露出部３２の両側に形成される正極合材層３１上にも貼着されている。絶縁テープ４０は、さらに、正極リード１９が溶接される一方側の露出部３２と反対側に形成される他方側の露出部３２にも貼着されることが好ましい。即ち、絶縁テープ４０は、各露出部３２を覆って正極１１の両面にそれぞれ貼着される。 The insulating tape 40 has, for example, a rectangular shape (strip shape) in a front view wider than the electrode leads. The insulating tape 40 is preferably attached to cover the entire base of the electrode lead. In the example shown in FIG. 2, the entire base of the positive electrode lead 19 and the entire exposed portion 32 are covered with the insulating tape 40. In addition, a part of the insulating tape 40 is attached also on the positive electrode mixture layer 31 formed on both sides of the exposed portion 32. The insulating tape 40 is preferably further adhered to the other exposed portion 32 formed on the opposite side of the exposed portion 32 to which the positive electrode lead 19 is welded. That is, the insulating tape 40 is adhered to both surfaces of the positive electrode 11 so as to cover the exposed portions 32.
　また、絶縁テープ４０は、正極集電体３０の範囲を超えて、正極リード１９の延出部の付け根に貼着されていてもよい。正極リード１９の延出部の付け根部分はセパレータ１３を介して負極１２と対向するため、セパレータ１３の溶融による内部短絡の発生が懸念される。ゆえに、当該付け根部分にも絶縁テープ４０が貼着されていることが好ましい。絶縁テープ４０は、負極リード２０および露出部３７にも、正極１１の場合と同様に貼着されるが、図２に示す例では、負極リード２０の基部の全体と露出部３７の一部を覆って貼着されている。 In addition, the insulating tape 40 may be attached to the base of the extension of the positive electrode lead 19 beyond the range of the positive electrode current collector 30. The base portion of the extended portion of the positive electrode lead 19 faces the negative electrode 12 through the separator 13, so there is a concern that the internal short circuit may occur due to the melting of the separator 13. Therefore, it is preferable that the insulating tape 40 be stuck also to the said root part. The insulating tape 40 is attached to the negative electrode lead 20 and the exposed portion 37 as in the case of the positive electrode 11, but in the example shown in FIG. 2, the entire base of the negative electrode lead 20 and a part of the exposed portion 37 It is covered and stuck.
　図３は、絶縁テープ４０が貼着された電極６０を示す図であって、（ａ）は正面図、（ｂ）は（ａ）中のＡＡ線断面図である。なお、電極６０は正極、負極のどちらであってもよい。図３に例示するように、絶縁テープ４０は、合材層６２と集電体６１の露出部６３との境界部に沿って、当該境界部を覆うように電極６０に貼着されていてもよい。図３に示す例では、合材層６２の端部と露出部６３とに跨って絶縁テープ４０が貼着されている。絶縁テープ４０は、電極６０の片面のみに貼着されていてもよく、両面に貼着されていてもよい。 FIG. 3 is a view showing the electrode 60 to which the insulating tape 40 is attached, where (a) is a front view and (b) is a cross-sectional view taken along line AA in (a). The electrode 60 may be either a positive electrode or a negative electrode. As illustrated in FIG. 3, the insulating tape 40 may be attached to the electrode 60 along the boundary between the mixture layer 62 and the exposed portion 63 of the current collector 61 so as to cover the boundary. Good. In the example shown in FIG. 3, the insulating tape 40 is attached across the end of the mixture layer 62 and the exposed portion 63. The insulating tape 40 may be attached to only one side of the electrode 60 or may be attached to both sides.
　図４は、実施形態の一例である絶縁テープ４０の断面図である。図４に例示するように、絶縁テープ４０は、絶縁性の有機材料で構成された基材層４１と、接着剤層４２と、基材層４１と接着剤層４２との間に介在し、熱伝導性フィラーとして、炭素系フィラーおよび金属フィラーの少なくとも一方を含有する熱伝導層４３とを有する。熱伝導性フィラーの含有量は、熱伝導層４３の体積に対して２５体積％以上であることが好ましい。絶縁テープ４０は、電池性能に影響を与えることなく内部短絡を抑制する。そして、熱伝導層４３の機能により、万が一、導電性の異物がテープを突き破り内部短絡が発生しても、速やかに放熱できるので、セパレータ１３および基材層４１の変形変質を抑制でき、短絡箇所の拡大による電池温度の上昇を抑えることができる。 FIG. 4 is a cross-sectional view of an insulating tape 40 which is an example of the embodiment. As illustrated in FIG. 4, the insulating tape 40 is interposed between the base layer 41 made of an insulating organic material, the adhesive layer 42, and the base layer 41 and the adhesive layer 42, A thermally conductive layer 43 containing at least one of a carbon-based filler and a metal filler is provided as the thermally conductive filler. The content of the thermally conductive filler is preferably 25% by volume or more with respect to the volume of the thermally conductive layer 43. The insulating tape 40 suppresses an internal short circuit without affecting the battery performance. And, by the function of the heat conduction layer 43, even if the conductive foreign matter breaks through the tape and an internal short circuit occurs by any chance, the heat can be dissipated promptly, so that the deformation and degeneration of the separator 13 and the base material layer 41 can be suppressed. The increase in battery temperature due to the expansion of
　絶縁テープ４０の厚みは、例えば１０～６０μｍであり、好ましくは１５μｍ～４０μｍである。絶縁テープ４０および各層の厚みは、走査型電子顕微鏡（ＳＥＭ）を用いた断面観察により測定できる。絶縁テープ４０は、４層以上の層構造を有していてもよい。例えば、基材層４１は単層構造に限定されず、２層以上の同種または異種積層フィルムによって構成されてもよい。 The thickness of the insulating tape 40 is, for example, 10 to 60 μm, and preferably 15 to 40 μm. The thickness of the insulating tape 40 and each layer can be measured by cross-sectional observation using a scanning electron microscope (SEM). The insulating tape 40 may have a layer structure of four or more layers. For example, the base material layer 41 is not limited to a single layer structure, and may be constituted by two or more layers of the same or different laminated films.
　基材層４１は、実質的に有機材料のみで構成されることが好ましい。基材層４１の構成材料に占める有機材料の割合は、例えば９０重量％以上であり、好ましくは９５重量％以上、あるいは１００重量％であってもよい。有機材料の主成分は、絶縁性、耐電解液性、耐熱性、突き刺し強度等に優れる樹脂であることが好ましい。基材層４１の厚みは、例えば５～５０μｍであり、好ましくは１５～３５μｍである。 The base layer 41 is preferably substantially made of only an organic material. The ratio of the organic material to the constituent material of the base material layer 41 is, for example, 90% by weight or more, preferably 95% by weight or more, or 100% by weight. The main component of the organic material is preferably a resin which is excellent in insulation, electrolyte resistance, heat resistance, puncture strength and the like. The thickness of the base layer 41 is, for example, 5 to 50 μm, preferably 15 to 35 μm.
　基材層４１を構成する好適な樹脂としては、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）、ポリアミドなどが例示できる。これらは、１種類を単独で用いてもよく、２種類以上を組み合わせて用いてもよい。中でも、機械的強度（突き刺し強度）が高いポリイミドが特に好ましい。基材層４１には、例えばポリイミドで構成される樹脂フィルムを用いることができる。 As a suitable resin which comprises the base material layer 41, polyesters, such as a polyethylene terephthalate (PET), a polypropylene (PP), a polyimide (PI), polyphenylene sulfide (PPS), a polyether imide (PEI), a polyamide etc. can be illustrated. . One of these may be used alone, or two or more of these may be used in combination. Among them, polyimide having high mechanical strength (piercing strength) is particularly preferable. For the base material layer 41, for example, a resin film made of polyimide can be used.
　接着剤層４２は、正極リード１９に対する接着性を絶縁テープ４０に付与するための層である。接着剤層４２は、例えば熱伝導層４３が形成された基材層４１の一方の面上に接着剤を塗工して形成される。接着剤層４２は、基材層４１の場合と同様に、絶縁性、耐電解液性等に優れた接着剤（樹脂）を用いて構成されることが好ましい。接着剤層４２を構成する接着剤は、加熱することで粘着性を発現するホットメルト型または加熱により硬化する熱硬化型であってもよいが、生産性等の観点から、室温で粘着性を有するものが好ましい。接着剤層４２を構成する接着剤の一例は、アクリル系接着剤、合成ゴム系接着剤である。接着剤層４２は、例えば３～２０μｍの厚みである。 The adhesive layer 42 is a layer for providing the insulating tape 40 with adhesiveness to the positive electrode lead 19. The adhesive layer 42 is formed, for example, by applying an adhesive on one surface of the base layer 41 on which the heat conductive layer 43 is formed. As in the case of the base layer 41, the adhesive layer 42 is preferably configured using an adhesive (resin) that is excellent in insulation properties, electrolytic solution resistance, and the like. The adhesive constituting the adhesive layer 42 may be a hot melt type which exhibits adhesiveness by heating or a thermosetting type which cures by heating, but from the viewpoint of productivity etc. It is preferable to have. An example of the adhesive constituting the adhesive layer 42 is an acrylic adhesive or a synthetic rubber adhesive. The adhesive layer 42 has a thickness of, for example, 3 to 20 μm.
　熱伝導層４３は、上述の通り、熱伝導性フィラーとして、炭素系フィラーおよび金属フィラーの少なくとも一方を含有する層である。熱伝導層４３は、熱伝導性フィラーと、有機材料とで構成される複合層であって、有機材料からなるマトリックス中に熱伝導性フィラーが分散した層構造、ないし熱伝導性フィラーが有機材料で結着されてなる層構造を有する。 The heat conductive layer 43 is a layer containing at least one of a carbon-based filler and a metal filler as a heat conductive filler as described above. The thermally conductive layer 43 is a composite layer composed of a thermally conductive filler and an organic material, and has a layer structure in which the thermally conductive filler is dispersed in a matrix made of an organic material, or a thermally conductive filler is an organic material. Have a layered structure formed by bonding.
　熱伝導層４３は、例えば熱伝導性フィラーを有機材料に分散させ、これを基材層４１を構成する樹脂フィルムの表面に塗布し、塗膜を硬化させることで形成される。あるいは、熱伝導性フィラーを有機材料の溶液に分散させ、当該溶液を樹脂フィルムの表面に塗布し、溶媒を揮発除去して塗膜を乾燥させることで形成される。熱伝導層４３の好適な厚みは、１～１０μｍである。この場合、十分な放熱性、耐熱性を確保することが容易になる。 The heat conductive layer 43 is formed, for example, by dispersing a heat conductive filler in an organic material, applying it to the surface of the resin film constituting the base layer 41, and curing the coating film. Alternatively, it is formed by dispersing a thermally conductive filler in a solution of an organic material, applying the solution to the surface of a resin film, evaporating off the solvent, and drying the coating. The preferred thickness of the heat conduction layer 43 is 1 to 10 μm. In this case, it becomes easy to secure sufficient heat dissipation and heat resistance.
　熱伝導性フィラーの含有量は、熱伝導層４３の体積に対して、好ましくは２５～７０体積％、より好ましくは２５～５０体積％である。熱伝導性フィラーの含有量が当該範囲内であれば、良好な伝熱パスが形成され、熱伝導性に優れた熱伝導層４３が形成される。絶縁テープ４０では、基材層４１を設けると共に、基材層４１と接着剤層４２の間に熱伝導層４３を介在させることで、熱伝導層４３の熱伝導性フィラーの添加量を多くしても、良好な突き刺し強度を確保できる。 The content of the thermally conductive filler is preferably 25 to 70% by volume, more preferably 25 to 50% by volume, with respect to the volume of the thermally conductive layer 43. If the content of the thermally conductive filler is within the above range, a good heat transfer path is formed, and the thermally conductive layer 43 excellent in thermal conductivity is formed. In the insulating tape 40, the base layer 41 is provided, and the thermally conductive layer 43 is interposed between the base layer 41 and the adhesive layer 42, whereby the amount of the thermally conductive filler added to the thermally conductive layer 43 is increased. However, good stab strength can be secured.
　熱伝導層４３を構成する好適な炭素系フィラーとしては、ダイヤモンド、黒鉛、および炭素繊維から選択される少なくとも１種である。これらは、熱伝導性が高く、熱伝導層４３の放熱機能を向上させる。粒状の炭素系フィラーを用いる場合、その平均粒径は１μｍ以下であることが好ましい。熱伝導層４３には、１種または複数種の炭素系フィラーが含有されていてもよく、炭素系フィラーに加えて金属フィラーが含有されていてもよい。 As a suitable carbonaceous filler which constitutes heat conduction layer 43, it is at least one sort chosen from diamond, graphite, and carbon fiber. These have high thermal conductivity and improve the heat dissipation function of the thermal conductive layer 43. When a particulate carbon-based filler is used, the average particle size is preferably 1 μm or less. The heat conduction layer 43 may contain one or more carbon-based fillers, and may contain metal fillers in addition to the carbon-based fillers.
　好適な金属フィラーは、アルミニウム、チタン、シリコン、マグネシウム、およびステンレス鋼から選択される少なくとも１種を主成分とする金属で構成される。これらは、電解液中での化学的安定性が良好で、熱伝導性にも優れる。ここで、主成分とは、金属フィラーを構成する金属成分のうち最も重量が多い成分を意味する（後述の金属箔についても同様）。金属フィラーは、例えばアルミニウム合金等の合金で構成されていてもよく、アルミニウム等の１種の金属のみで構成されてもよい。金属フィラーの形状は、特に限定されず、粒状、針状、板状、繊維状のいずれであってもよい。熱伝導層４３には、１種または複数種の金属フィラーが含有されていてもよい。 Preferred metal fillers are composed of metals based on at least one selected from aluminum, titanium, silicon, magnesium, and stainless steel. These have good chemical stability in the electrolyte and are also excellent in thermal conductivity. Here, the main component means a component having the largest weight among the metal components constituting the metal filler (the same applies to metal foil described later). The metal filler may be made of, for example, an alloy such as an aluminum alloy, or may be made of only one metal such as aluminum. The shape of the metal filler is not particularly limited, and may be granular, needle-like, plate-like or fibrous. The heat conduction layer 43 may contain one or more metal fillers.
　熱伝導層４３を構成する有機材料（樹脂）は、基材層４１の場合と同様に、絶縁性、耐電解液性等に優れ、かつ基材層４１に対する接着性が良好であることが好ましい。好適な樹脂としては、アクリル樹脂、エポキシ樹脂、ウレタン樹脂、およびＰＶｄＦ等のフッ素樹脂などが例示できる。これらは、１種類を単独で用いてもよく、２種類以上を組み合わせて用いてもよい。 As in the case of the base material layer 41, it is preferable that the organic material (resin) constituting the heat conduction layer 43 is excellent in insulation, electrolyte resistance, etc., and has good adhesion to the base material layer 41. . Examples of suitable resins include acrylic resins, epoxy resins, urethane resins, and fluorine resins such as PVdF. One of these may be used alone, or two or more of these may be used in combination.
　図５は、実施形態の他の一例である絶縁テープ５０の断面図である。なお、図５では、図４に示す絶縁テープ４０と同様の構成要素に同じ番号を付している。図５に例示するように、絶縁テープ５０は、基材層４１と、接着剤層４２と、基材層４１と接着剤層４２との間に介在する金属箔からなる熱伝導層５３とを有する。即ち、絶縁テープ５０の構成は、熱伝導層４３の代わりに熱伝導層５３が設けられている点で、絶縁テープ４０の構成と異なる。なお、絶縁テープ５０を用いた場合にも、絶縁テープ４０を用いた場合と同様の機能、効果が得られる。 FIG. 5 is a cross-sectional view of an insulating tape 50 which is another example of the embodiment. In FIG. 5, the same components as those of the insulating tape 40 shown in FIG. 4 are denoted by the same reference numerals. As illustrated in FIG. 5, the insulating tape 50 includes a base layer 41, an adhesive layer 42, and a thermally conductive layer 53 made of metal foil interposed between the base layer 41 and the adhesive layer 42. Have. That is, the configuration of the insulating tape 50 differs from the configuration of the insulating tape 40 in that the heat conductive layer 53 is provided instead of the heat conductive layer 43. Even when the insulating tape 50 is used, the same function and effect as the case where the insulating tape 40 is used can be obtained.
　熱伝導層５３の好適な厚みは、１～１０μｍである。この場合、熱伝導層５３は厚みが１～１０μｍの金属箔を用いて形成される。絶縁テープ５０は、例えば熱伝導層５３を構成する金属箔上に、基材層４１を構成する樹脂の溶液を塗布し、塗膜を乾燥させることで形成される。あるいは、金属箔上に未硬化樹脂を塗布し、塗膜を硬化させることで基材層４１を形成してもよい。また、熱伝導層５３を構成する金属箔と、基材層４１を構成する樹脂フィルムを接着剤を用いて接合してもよい。 The preferred thickness of the heat conduction layer 53 is 1 to 10 μm. In this case, the heat conduction layer 53 is formed using a metal foil having a thickness of 1 to 10 μm. The insulating tape 50 is formed, for example, by applying a solution of the resin forming the base layer 41 on the metal foil forming the heat conductive layer 53 and drying the coating film. Alternatively, the base layer 41 may be formed by applying an uncured resin on a metal foil and curing the coating. Further, the metal foil constituting the heat conduction layer 53 and the resin film constituting the base layer 41 may be bonded using an adhesive.
　熱伝導層５３を構成する好適な金属箔は、アルミニウム、チタン、シリコン、マグネシウム、およびステンレス鋼から選択される少なくとも１種を主成分とする金属で構成される。これらは、電解液中での化学的安定性が良好で、熱伝導性にも優れる。金属箔は、例えばアルミニウム合金等の合金箔で構成されていてもよく、アルミニウム等の１種の金属箔のみで構成されてもよい。 A preferred metal foil constituting the heat conduction layer 53 is composed of a metal whose main component is at least one selected from aluminum, titanium, silicon, magnesium and stainless steel. These have good chemical stability in the electrolyte and are also excellent in thermal conductivity. The metal foil may be made of, for example, an alloy foil such as an aluminum alloy, or may be made of only one kind of metal foil such as aluminum.
　以下、実施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施例に限定されるものではない。 Hereinafter, the present disclosure will be further described by way of examples, but the present disclosure is not limited to these examples.
　＜実施例１＞
　[正極の作成］
　正極活物質としてＬｉＮｉ0.88Ｃｏ0.09Ａｌ0.03Ｏ2で表されるリチウムニッケルコバルトアルミニウム複合酸化物を１００重量部と、アセチレンブラック（ＡＢ）を１重量部と、ポリフッ化ビニリデン（ＰＶｄＦ）を１重量部とを混合し、さらにＮ－メチル－２－ピロリドン（ＮＭＰ）を適量加えて、正極合材スラリーを調製した。次に、当該正極合材スラリーをアルミニウム箔からなる正極集電体の両面に塗布し、塗膜を乾燥させた。塗膜が形成された集電体をローラーを用いて圧縮した後、所定の電極サイズに切断し、正極集電体の両面に正極合材層が形成された正極を作成した。正極の長手方向中央部に合材層が形成されず集電体表面が露出した露出部を設け、当該露出部にアルミニウム製の正極リードを超音波溶接した。 Example 1
[Create positive electrode]
100 parts by weight of lithium nickel cobalt aluminum complex oxide represented by LiNi 0.88 Co 0.09 Al 0.03 O 2 as a positive electrode active material, 1 part by weight of acetylene black (AB), and 1 part by weight of polyvinylidene fluoride (PVdF) And a proper amount of N-methyl-2-pyrrolidone (NMP) to prepare a positive electrode mixture slurry. Next, the positive electrode mixture slurry was applied to both sides of a positive electrode current collector made of aluminum foil, and the coating was dried. The current collector on which the coating film was formed was compressed using a roller, and then cut into a predetermined electrode size to prepare a positive electrode in which a positive electrode mixture layer was formed on both sides of the positive electrode current collector. An exposed portion in which the mixture layer was not formed at the central portion in the longitudinal direction of the positive electrode and the current collector surface was exposed was provided, and a positive electrode lead made of aluminum was ultrasonically welded to the exposed portion.
　正極リードの基部、延出部の付け根部分、および各露出部を覆うように、正極に絶縁テープを貼着した。絶縁テープの層構成は、下記の通りである。 An insulating tape was attached to the positive electrode so as to cover the base of the positive electrode lead, the base of the extension, and each exposed portion. The layer configuration of the insulating tape is as follows.
　基材層：厚み２５μｍのポリイミドフィルム　接着剤層：厚み７μｍのアクリル系接着剤層　熱伝導層：ダイヤモンドフィラー２５体積％と、アクリル樹脂７５体積％とで構成される、厚み１μｍの複合層
　[負極の作成］
　黒鉛粉末を９８重量部と、カルボキシメチルセルロースナトリウム（ＣＭＣ－Ｎａ）を１重量部と、スチレン－ブタジエンゴム（ＳＢＲ）を１重量部とを混合し、さらに水を適量加えて、負極合材スラリーを調製した。次に、当該負極合材スラリーを銅箔からなる負極集電体の両面に塗布し、塗膜を乾燥させた。塗膜が形成された集電体をローラーを用いて圧縮した後、所定の電極サイズに切断し、負極集電体の両面に負極合材層が形成された負極を作成した。負極の長手方向一端部（巻外側端部となる部分）に合材層が形成されず集電体表面が露出した露出部を設け、当該露出部にニッケル製の負極リードを超音波溶接した。 Base material layer: 25 μm thick polyimide film Adhesive layer: 7 μm thick acrylic adhesive layer Thermal conductive layer: 1 μm thick composite layer composed of 25 volume% of diamond filler and 75 volume% of acrylic resin Creation of]
Mix 98 parts by weight of graphite powder, 1 part by weight of sodium carboxymethylcellulose (CMC-Na), and 1 part by weight of styrene-butadiene rubber (SBR), add an appropriate amount of water, and mix the negative electrode slurry Prepared. Next, the negative electrode mixture slurry was applied to both sides of a negative electrode current collector made of copper foil, and the coating was dried. The current collector on which the coating film was formed was compressed using a roller, and then cut into a predetermined electrode size to prepare a negative electrode in which a negative electrode mixture layer was formed on both sides of the negative electrode current collector. An exposed portion in which the mixture layer was not formed at one longitudinal end portion (portion to be the winding outer end portion) of the negative electrode and the current collector surface was exposed was provided, and a nickel negative electrode lead was ultrasonically welded to the exposed portion.
　負極リードの基部、延出部の付け根部分、および各露出部を覆うように、負極に上記絶縁テープを貼着した。 The above-mentioned insulating tape was stuck to the negative electrode so as to cover the base of the negative electrode lead, the root portion of the extending portion, and each exposed portion.
　[電解質の調製］
　エチレンカーボネート（ＥＣ）と、エチルメチルカーボネート（ＥＭＣ）と、ジメチルカーボネート（ＤＭＣ）を、３：３：４の体積比で混合した。当該混合溶媒に、ＬｉＰＦ6を１ｍｏｌ／Ｌの濃度で溶解させて非水電解質を調製した。 [Preparation of electrolyte]
Ethylene carbonate (EC), ethyl methyl carbonate (EMC) and dimethyl carbonate (DMC) were mixed in a volume ratio of 3: 3: 4. In the mixed solvent, LiPF 6 was dissolved at a concentration of 1 mol / L to prepare a non-aqueous electrolyte.
　[電池の作成］
　上記正極と上記負極を、ポリアミドおよびアルミナのフィラーが分散した耐熱層が片面に形成されたポリエチレン製多孔質膜からなるセパレータを介して渦巻状に巻回することにより巻回型の電極体を作成した。この電極体を有底円筒形状の金属製ケース本体（外径１８ｍｍ、高さ６５ｍｍ）に収容した後、正極リードの延出部を封口体のフィルタに、負極リードの延出部をケース本体の底部内面にそれぞれ溶接した。そして、ケース本体に上記非水電解液を注入し、封口体によりケース本体の開口部を塞いで、１８６５０型の円筒形電池を作成した。 [Create battery]
A winding type electrode body is formed by spirally winding the positive electrode and the negative electrode through a separator made of a porous film made of polyethylene having a heat resistant layer in which fillers of polyamide and alumina are dispersed on one side. did. After this electrode body is housed in a metal case main body (outside diameter 18 mm, height 65 mm) with a bottomed cylindrical shape, the extension of the positive electrode lead is used as a filter of the sealing body and the extension of the negative electrode lead is Each was welded to the bottom inner surface. Then, the non-aqueous electrolyte was injected into the case main body, and the opening of the case main body was closed with a sealing member, to prepare a 18650 type cylindrical battery.
　＜実施例２～６＞
　実施例１で用いた絶縁テープの熱伝導層を表１に示すものとした以外は、実施例１と同様にして円筒形電池を作成した。 Examples 2 to 6
A cylindrical battery was produced in the same manner as in Example 1 except that the heat conduction layer of the insulating tape used in Example 1 was as shown in Table 1.
　＜実施例７＞
　実施例１で用いた絶縁テープに代えて、下記層構造を有する絶縁テープを用いたこと以外は、実施例１と同様にして円筒形電池を作成した。 Example 7
A cylindrical battery was produced in the same manner as in Example 1, except that the insulating tape used in Example 1 was replaced by an insulating tape having the following layer structure.
　基材層：厚み２５μｍのポリイミドフィルム　接着剤層：厚み７μｍのアクリル系接着剤層　熱伝導層：厚み１μｍのアルミニウム箔（ポリイミドフィルムの片面にアクリル系接着剤を塗布して、アルミニウム箔を接着した）
　＜実施例８＞
　実施例７で用いた絶縁テープの熱伝導層を表１に示すものとした以外は、実施例７と同様にして円筒形電池を作成した。 Base material layer: 25 μm thick polyimide film Adhesive layer: 7 μm thick acrylic adhesive layer Thermal conductive layer: 1 μm thick aluminum foil (an acrylic adhesive is applied to one side of a polyimide film, and the aluminum foil is adhered )
Example 8
A cylindrical battery was produced in the same manner as in Example 7 except that the heat conduction layer of the insulating tape used in Example 7 was changed to that shown in Table 1.
　＜比較例１＞
　実施例１で用いた絶縁テープに代えて、下記層構造を有する絶縁テープを用いたこと以外は、実施例１と同様にして円筒形電池を作成した。 Comparative Example 1
A cylindrical battery was produced in the same manner as in Example 1, except that the insulating tape used in Example 1 was replaced by an insulating tape having the following layer structure.
　基材層：厚み２５μｍのポリイミドフィルム　接着剤層：厚み７μｍのアクリル系接着剤層　熱伝導層：シリカゾル２５体積％と、アクリル樹脂７５体積％とで構成される、厚み１μｍの複合層
　＜比較例２＞
　熱伝導層を有さない絶縁テープ（ポリイミドフィルムと、アクリル系接着剤層とで構成される絶縁テープ）を用いたこと以外は、実施例１と同様にして円筒形電池を作成した。 Base material layer: 25 μm thick polyimide film Adhesive layer: 7 μm thick acrylic adhesive layer Thermal conductive layer: 1 μm thick composite layer composed of 25 vol% of silica sol and 75 vol% of acrylic resin <Comparative example 2>
A cylindrical battery was produced in the same manner as in Example 1 except that an insulating tape having no heat conductive layer (an insulating tape composed of a polyimide film and an acrylic adhesive layer) was used.
　実施例および比較例の各電池について、下記の方法で異物短絡試験および保存試験を行った。また、実施例および比較例の各絶縁テープに含まれる水分量を測定した。試験結果、測定結果を表１に示す。 About each battery of an Example and a comparative example, the foreign material short circuit test and the storage test were done with the following method. Moreover, the moisture content contained in each insulation tape of an Example and a comparative example was measured. The test results and the measurement results are shown in Table 1.
　[異物短絡試験］
　各電池を、電流値５００ｍＡで、充電終止電圧４．２Ｖまで定電流充電し、４．２Ｖで６０分間、定電圧充電を行った。正極リードの絶縁テープが貼着された部分と、セパレータとの間に導電性の異物を仕込み、ＪＩＳ　Ｃ　８７１４に従い、強制的に短絡させたときの電池の側面温度を熱電対で測定した。測定結果は表１に示した。 [Foreign matter short circuit test]
Each battery was constant current charged to a charge termination voltage of 4.2 V at a current value of 500 mA, and constant voltage charging was performed at 4.2 V for 60 minutes. A conductive foreign matter was placed between the separator and the portion of the positive electrode lead where the insulating tape was attached, and the side surface temperature of the battery when forced short circuit was measured with a thermocouple according to JIS C 8714. The measurement results are shown in Table 1.
　[保存試験］
　各電池を、電流値５００ｍＡで、充電終止電圧４．２Ｖまで定電流充電し、４．２Ｖで６０分間、定電圧充電を行った。充電状態の各電池を開回路状態、６０℃で１ヶ月保存した後、電流値５００ｍＡで、放電終止電圧２．５Ｖまで定電流放電し、充電容量に対する放電容量の割合を計算した。測定結果は表１に示した。なお、充放電は全て２５℃の環境下で行った。 [Preservation test]
Each battery was constant current charged to a charge termination voltage of 4.2 V at a current value of 500 mA, and constant voltage charging was performed at 4.2 V for 60 minutes. After each battery in a charged state was stored at 60 ° C. for one month in an open circuit state, constant current discharge was performed to a discharge termination voltage of 2.5 V at a current value of 500 mA, and the ratio of the discharge capacity to the charge capacity was calculated. The measurement results are shown in Table 1. In addition, all charging / discharging was performed in the environment of 25 degreeC.
　各電池に用いた絶縁テープに含まれる水分量をカールフィッシャー法を用いて測定した。加熱温度は、１５０℃とした。 The amount of water contained in the insulating tape used for each battery was measured using the Karl Fischer method. The heating temperature was 150.degree.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　表１に示すように、実施例の電池はいずれも、比較例１の電池と比べて、充電保存後の容量残存率が高かった。実施例の電池に用いた絶縁テープは比較例１で用いた絶縁テープよりも水分含有量が少なく、このことが実施例の各電池が比較例１の電池よりも充電保存特性が向上した要因であると考えられる。 As shown in Table 1, all of the batteries of Examples had higher residual capacity rates after charge storage, as compared to the batteries of Comparative Example 1. The insulating tape used for the battery of Example has a moisture content lower than that of the insulating tape used in Comparative Example 1, and this is the reason why the batteries of the Example have improved charge storage characteristics over the battery of Comparative Example 1. It is believed that there is.
　表１に示すように、実施例の電池はいずれも、比較例の電池と比べて、異物短絡時の電池温度が低かった。実施例の電池では、絶縁テープの熱伝導層の機能により、短絡で発生した熱を速やかに拡散でき、このことが電池温度の上昇抑制につながったものと考えられる。即ち、熱伝導層の放熱機能により、基材層およびセパレータの変形変質を抑制でき、短絡箇所の拡大による電池温度の上昇を抑えることできる。 As shown in Table 1, in all the batteries of the example, the battery temperature at the time of the foreign matter short circuit was lower than that of the battery of the comparative example. In the battery of the example, it is considered that the heat generated in the short circuit can be diffused quickly by the function of the heat conduction layer of the insulating tape, which leads to the suppression of the rise of the battery temperature. That is, the heat dissipating function of the heat conduction layer can suppress the deformation and deterioration of the base material layer and the separator, and can suppress the increase in battery temperature due to the expansion of the short circuit portion.
　１０　二次電池
　１１　正極
　１２　負極
　１３　セパレータ
　１４　電極体
　１５　ケース本体
　１６　封口体
　１７，１８　絶縁板
　１９　正極リード
　２０　負極リード
　２１　張り出し部
　２２　フィルタ
　２３　下弁体
　２４　絶縁部材
　２５　上弁体
　２６　キャップ
　２７　ガスケット
　３０　正極集電体
　３１　正極合材層
　３２，３７　露出部
　３５　負極集電体
　３６　負極合材層
　４０，５０　絶縁テープ
　４１　基材層
　４２　接着剤層
　４３，５３　熱伝導層 DESCRIPTION OF SYMBOLS 10 Secondary battery 11 Positive electrode 12 Negative electrode 13 Separator 14 Electrode body 15 Case main body 16 Sealing body 17, 18 Insulating plate 19 Positive electrode lead 20 Negative electrode lead 21 Projection part 22 Filter 23 Lower valve body 24 Insulating member 25 Upper valve body 26 Cap 27 Gasket REFERENCE SIGNS LIST 30 positive electrode current collector 31 positive electrode mixture layer 32, 37 exposed portion 35 negative electrode current collector 36 negative electrode mixture layer 40, 50 insulating tape 41 base material layer 42 adhesive layer 43, 53 thermally conductive layer

Claims (9)

  1. 　正極と負極がセパレータを介して積層されてなる電極体を備えた二次電池において、
    　前記正極および前記負極は、集電体と、前記集電体上に形成された合材層と、前記集電体の表面が露出した露出部に接続された電極リードとを有し、
    　前記正極および前記負極の少なくとも一方において、前記電極リードおよび前記露出部の少なくとも一方に貼着された絶縁テープを備え、
    　前記絶縁テープは、絶縁性の有機材料で構成された基材層と、接着剤層と、前記基材層と前記接着剤層との間に介在し、熱伝導性フィラーとして、炭素系フィラーおよび金属フィラーの少なくとも一方を含有する熱伝導層とを有する、二次電池。     In a secondary battery provided with an electrode body in which a positive electrode and a negative electrode are stacked via a separator,
    The positive electrode and the negative electrode have a current collector, a mixture layer formed on the current collector, and an electrode lead connected to an exposed portion where the surface of the current collector is exposed.
    In at least one of the positive electrode and the negative electrode, an insulating tape attached to at least one of the electrode lead and the exposed portion,
    The insulating tape is interposed between a base layer made of an insulating organic material, an adhesive layer, the base layer and the adhesive layer, and a carbon-based filler as a thermally conductive filler And a heat conductive layer containing at least one of the metal fillers.
  2. 　前記熱伝導性フィラーの含有量は、前記熱伝導層の体積に対して２５体積％以上である、請求項１に記載の二次電池。 The secondary battery according to claim 1, wherein a content of the thermally conductive filler is 25% by volume or more with respect to a volume of the thermally conductive layer.
  3. 　前記炭素系フィラーは、ダイヤモンド、黒鉛、および炭素繊維から選択される少なくとも１種である、請求項１または２に記載の二次電池。 The secondary battery according to claim 1, wherein the carbon-based filler is at least one selected from diamond, graphite, and carbon fibers.
  4. 　前記金属フィラーは、アルミニウム、チタン、シリコン、マグネシウム、およびステンレス鋼から選択される少なくとも１種を主成分とする金属で構成される、請求項１～３のいずれか１項に記載の二次電池。 The secondary battery according to any one of claims 1 to 3, wherein the metal filler is composed of a metal containing at least one selected from aluminum, titanium, silicon, magnesium, and stainless steel. .
  5. 　正極と負極がセパレータを介して積層されてなる電極体を備えた二次電池において、
    　前記正極および前記負極は、集電体と、前記集電体上に形成された合材層と、前記集電体の表面が露出した露出部に接続された電極リードとを有し、
    　前記正極および前記負極の少なくとも一方において、前記電極リードおよび前記露出部の少なくとも一方に貼着された絶縁テープを備え、
    　前記絶縁テープは、絶縁性の有機材料で構成された基材層と、接着剤層と、前記基材層と前記接着剤層との間に介在する金属箔からなる熱伝導層とを有する、二次電池。     In a secondary battery provided with an electrode body in which a positive electrode and a negative electrode are stacked via a separator,
    The positive electrode and the negative electrode have a current collector, a mixture layer formed on the current collector, and an electrode lead connected to an exposed portion where the surface of the current collector is exposed.
    In at least one of the positive electrode and the negative electrode, an insulating tape attached to at least one of the electrode lead and the exposed portion,
    The insulating tape has a base layer made of an insulating organic material, an adhesive layer, and a thermally conductive layer made of metal foil interposed between the base layer and the adhesive layer. Secondary battery.
  6. 　前記金属箔は、アルミニウム、チタン、シリコン、マグネシウム、およびステンレス鋼から選択される少なくとも１種を主成分とする金属で構成される、請求項５に記載の二次電池。 The secondary battery according to claim 5, wherein the metal foil is made of a metal having at least one selected from aluminum, titanium, silicon, magnesium, and stainless steel.
  7. 　前記熱伝導層の厚みが１～１０μｍである、請求項１～６のいずれか１項に記載の二次電池。 The secondary battery according to any one of claims 1 to 6, wherein the thickness of the heat conduction layer is 1 to 10 μm.
  8. 　前記基材層は、ポリイミドで構成される、請求項１～７のいずれか１項に記載の二次電池。 The secondary battery according to any one of claims 1 to 7, wherein the base material layer is made of polyimide.
  9. 　前記絶縁テープは、少なくとも前記正極に貼着されている、請求項１～８のいずれか１項に記載の二次電池。 The secondary battery according to any one of claims 1 to 8, wherein the insulating tape is attached to at least the positive electrode.
PCT/JP2018/024997 2017-09-11 2018-07-02 Secondary battery WO2019049485A1 (en)

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