Battery

Abstract

A battery (10) comprises: a bottomed cylindrical outer can (16) that has an opening and accommodates an electrode body; a sealing body (17) that covers the opening of the outer can (16); a gasket (28) that is disposed between the outer can (16) and the sealing body (17); and a resistance layer (30) that is disposed between an end tip (16a) on the opening side of the outer can (16) and the upper surface of the sealing body (17) facing the end tip (16a), and that has a penetration resistance value of 0.05 Ω or more and 10 kΩ or less.

Description

battery

[0001] The present disclosure relates to battery technology.

[0002] Batteries such as lithium-ion secondary batteries are widely used as power sources for portable electronic devices, such as mobile phones, smartphones, portable game consoles, and laptop computers. While there is a trend toward ever-increasing battery capacity, ensuring safety is also becoming increasingly important.

[0003] Regarding the safety of the battery, for example, Patent Document 1 proposes a battery in which, in order to prevent a short circuit between the outer can and the sealing body, at least one of the surfaces of the metal material of the outer can and the surface of the metal material of the sealing body is coated with an insulating film in a portion near the portion where the outer can and the sealing body are in contact with each other via a gasket, which is an insulating layer, and which may be short-circuited by a conductive foreign object that has entered that portion.

[0004] Japanese Patent Application Publication No. 10-294093

[0005] According to Patent Document 1, even if the gasket, which is an insulating layer, melts due to some abnormality, a short circuit between the outer can and the sealing body at the insulating layer (gasket portion) (hereinafter referred to as an insulating layer short circuit or a gasket short circuit) is prevented by the insulating film, thereby suppressing an increase in battery temperature due to the short circuit. However, even if the gasket, which is an insulating layer, melts, the insulating film ensures insulation between the outer can and the sealing body, so the battery voltage does not decrease, and therefore the battery abnormality cannot be detected by the battery voltage. In other words, there is a risk that the battery will continue to be used even after the gasket melts.

[0006] Therefore, an object of the present disclosure is to provide a battery that suppresses an increase in battery temperature due to a gasket short circuit and that does not cause a drop in battery voltage when the insulating layer melts.

[0007] A battery according to one aspect of the present disclosure is characterized by comprising: a bottomed cylindrical outer can having an opening and accommodating an electrode assembly; a sealing body covering the opening of the outer can; an insulating layer disposed between the outer can and the sealing body; and a resistive layer having a through resistance value of 0.05 Ω or more and 10 kΩ or less, disposed between a tip of an end of the outer can on the opening side and an upper surface of the sealing body facing the tip of the end.

[0008] According to one aspect of the present disclosure, it is possible to provide a battery that suppresses an increase in battery temperature due to an insulating layer short circuit and that does not cause a drop in battery voltage when the insulating layer melts.

[0009] 1 is a cross-sectional view of a battery according to an embodiment of the present invention; FIG. 2 is a partially enlarged cross-sectional view of the battery shown in FIG.

[0010] Hereinafter, an example of an embodiment of a battery according to the present disclosure will be described with reference to the drawings. Note that the battery according to the present disclosure is not limited to the embodiment described below.

[0011] Fig. 1 is a cross-sectional view of a battery according to an embodiment. The battery 10 shown in Fig. 1 includes a wound electrode assembly 14 formed by winding a positive electrode 11 and a negative electrode 12 with a separator 13 interposed therebetween, an electrolyte, insulating plates 18 and 19 disposed above and below the electrode assembly 14, respectively, and a battery case 15. The battery case 15 includes a cylindrical outer can 16 with a bottom and an opening for accommodating the above-mentioned components, such as the electrode assembly 14, and a sealing member 17 for covering the opening of the outer can 16. Note that, instead of the wound electrode assembly 14, an electrode assembly of another type may be used, such as a stacked electrode assembly formed by alternately stacking positive and negative electrodes with separators interposed therebetween.

[0012] The electrolyte has, for example, ion conductivity (for example, lithium ion conductivity). The electrolyte may be a liquid electrolyte (electrolytic solution) or a solid electrolyte.

[0013] The liquid electrolyte (electrolytic solution) contains, for example, a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. Examples of the non-aqueous solvent include esters, ethers, nitriles, amides, and mixed solvents of two or more of these. 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 compound (e.g., fluoroethylene carbonate) in which at least a portion of the hydrogen atoms of these solvents are substituted with halogen atoms such as fluorine. Examples of the electrolyte salt include LiPF ６Lithium salts such as

[0014] Furthermore, examples of the solid electrolyte that can be used include solid or gel-like polymer electrolytes, inorganic solid electrolytes, and the like. 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. For example, a polymer material that absorbs a non-aqueous solvent and gels is used as the matrix polymer. Examples of the polymer material include fluororesin, acrylic resin, and polyether resin. For example, the inorganic solid electrolyte can be a material known in all-solid-state lithium ion secondary batteries (e.g., oxide-based solid electrolytes, sulfide-based solid electrolytes, halogen-based solid electrolytes, and the like). While the above-exemplified electrolytes are non-aqueous electrolytes, the electrolyte is not limited to non-aqueous electrolytes and may be an aqueous electrolyte.

[0015] The outer can 16 is, for example, a cylindrical metal container with a bottom, such as a rectangular or cylindrical shape. The outer can 16 has a protruding portion 22, for example, a part of the side surface of the outer can 16 that protrudes inward and supports the sealing body 17. The protruding 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.

[0016] The sealing body 17 covers the opening of the outer can 16. The sealing body 17 has a structure in which, from the electrode body 14 side, a filter 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 the filter 23, the lower valve body 24, the upper valve body 26, and the cap 27 are, for example, made of metal. The filter 23, the lower valve body 24, the upper valve body 26, and the cap 27 are 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 an insulating member 25 is interposed between their respective peripheral edges. When the internal pressure of the battery 10 increases due to heat generation caused by an internal short circuit or the like, for example, the lower valve body 24 deforms and breaks, pushing the upper valve body 26 toward the cap 27, and the current path between the lower valve body 24 and the upper valve body 26 is interrupted. If the internal pressure increases further, the upper valve body 26 breaks and the gas is discharged from the opening of the cap 27 .

[0017] The battery 10 shown in FIG. 1 includes a gasket 28, which is an insulating layer. The gasket 28 is disposed between the outer can 16 and the sealing body 17. The gasket 28 is made of, for example, a rubber material. By disposing the gasket 28 between the outer can 16 and the sealing body 17, insulation between the outer can 16 and the sealing body 17 and sealing of the inside of the battery are ensured. The gasket 28 is used, for example, in the case of a battery 10, in order to ensure insulation between the outer can 16 and the sealing body 17. ５ Ω / cm ２ It is desirable that the resistance value be equal to or greater than this.

[0018] The sealing body 17 is crimped to the opening-side end of the outer can 16 via a gasket 28. Specifically, the opening-side end of the outer can 16 is bent inward and crimped toward the sealing body 17, so that the sealing body 17 is sandwiched between the protruding portion 22 of the outer can 16 and the inwardly bent opening-side end of the outer can 16 via the gasket 28. In the battery 10 shown in FIG. 1 , this crimping causes the opening-side end of the outer can 16 bent inward to have a curved shape. The opening-side end tip 16a of the outer can 16 faces the top surface of the sealing body 17. Here, the top surface of the sealing body 17 refers to the surface facing the outside of the battery. In this embodiment, the top surface of the cap 27 corresponds to the top surface of the sealing body 17. Furthermore, the opening-side end tip of the outer can 16 refers to the end surface (surface indicating the thickness) of the opening-side end of the outer can 16, and does not include the inner or outer wall of the outer can 16 at the end.

[0019] In the battery 10 shown in Figure 1, a positive electrode lead 20 attached to the positive electrode 11 passes through a through-hole in the insulating plate 18 and extends toward the sealing body 17, and a negative electrode lead 21 attached to the negative electrode 12 passes outside the insulating plate 19 and extends toward the bottom of the outer can 16. The positive electrode lead 20 is connected by welding or the like to the underside of a filter 23, which is the bottom plate of the sealing body 17, and a cap 27, which is the top plate of the sealing body 17 and is electrically connected to the filter 23, serves as the positive electrode terminal. The negative electrode lead 21 is connected by welding or the like to the inner bottom surface of the outer can 16, and the outer can 16 serves as the negative electrode terminal.

[0020] 2 and 3 are enlarged cross-sectional views of a portion of the battery shown in FIG. 1 . Although not shown in FIG. 1 , the battery 10 of this embodiment includes a resistive layer 30. The resistive layer 30 has a feedthrough resistance of 0.05 Ω or more and 10 kΩ or less. The feedthrough resistance is the resistance value in the thickness direction of the resistive layer 30, and is measured by the method described in the Examples. The resistive layer 30 may be disposed between the top surface of the sealing body 17 and the end tip 16 a on the opening side of the outer can 16 that faces the top surface of the sealing body 17.

[0021] 2, the resistance layer 30 may be disposed between the top surface of the cap 27 and a gasket 28 that is located between the top surface of the cap 27 and the end tip 16a on the opening side of the outer can 16. Alternatively, as shown in FIG. 3, the resistance layer 30 may be disposed inside the gasket 28 that is located between the top surface of the cap 27 and the end tip 16a on the opening side of the outer can 16. Although not shown in the drawings, the resistance layer 30 may be disposed between the gasket 28 that is located between the top surface of the cap 27 and the end tip 16a on the opening side of the outer can 16, and the end tip 16a on the opening side of the outer can 16. As a suitable positioning of the resistance layer 30, for example, in terms of ease of design and suppression of damage to the resistance layer 30 during crimping, it is preferable that the resistance layer 30 be positioned between the upper surface of the cap 27 and the end tip 16a on the opening side of the outer can 16, between the gasket 28 present therebetween and the upper surface of the cap 27, or inside the gasket 28 present therebetween, as shown in Figures 2 and 3.

[0022] If some abnormality such as an external short circuit occurs in the battery 10 and the gasket 28 melts, a short circuit will occur between the outer can 16 and the sealing body 17, and in particular, a short circuit is likely to occur between the top surface of the sealing body 17 (the top surface of the cap 27 in this embodiment) and the end tip 16a on the opening side of the outer can 16 that faces the top surface of the sealing body 17. One reason for this is that if the internal pressure of the battery 10 increases due to an abnormality in the battery 10, the sealing body 17 is pushed upward, making it easier for the top surface of the sealing body 17 to come into contact with the end tip 16a on the opening side of the outer can 16. In particular, due to the above-mentioned crimping, the end tip 16a on the opening side of the outer can 16 compresses the gasket 28 on the upper surface of the sealing body 17, and in some cases, as shown in Figures 1 to 3, the end tip 16a bites into the gasket 28 on the upper surface of the sealing body 17, so if the gasket 28 melts, there is a higher risk of the upper surface of the sealing body 17 and the end tip 16a on the opening side of the outer can 16 coming into contact with each other.

[0023] However, in this embodiment, even if some abnormality such as an external short circuit occurs in the battery 10 and the gasket 28 melts, the short-circuit current flowing between the top surface of the sealing body 17 and the end tip 16 a on the opening side of the outer can 16 is reduced by the resistance layer 30, thereby suppressing an increase in battery temperature due to the gasket short circuit. Furthermore, when the gasket 28 melts, the insulation between the top surface of the sealing body 17 and the end tip 16 a on the opening side of the outer can 16 is alleviated by the resistance layer 30, ensuring a certain degree of electrical conductivity between the outer can 16 and the sealing body 17, thereby allowing the battery voltage to be reduced. In other words, after the gasket 28 melts, it is possible to detect an abnormality in the battery 10 based on the drop in battery voltage.

[0024] The through resistance value of the resistance layer 30 may be 0.05 Ω or more and 10 kΩ or less, but is preferably 2 Ω or more and 3 kΩ or less, and more preferably 10 Ω or more and 1 kΩ or less, in that this can further suppress an increase in battery temperature due to a gasket short circuit while ensuring a decrease in battery voltage when the gasket 28 melts.

[0025] The resistive layer 30 shown in Fig. 2 can be obtained, for example, by attaching a sheet-like resistive layer to the upper surface of the cap 27 or by applying a resistive layer slurry to the upper surface of the cap 27. The resistive layer 30 shown in Fig. 3 can be obtained, for example, by molding the gasket 28 so that the sheet-like resistive layer is embedded inside. The resistive layer 30 is present all around or part of the circumferential direction of the cap 27 or the gasket 28.

[0026] The resistive layer 30 preferably has a heat resistance temperature of at least 200°C or higher so that it does not melt when the gasket is short-circuited. The heat resistance temperature of the resistive layer 30 is measured using a penetration probe thermomechanical analyzer (EXSTAR6000, manufactured by Seiko Electronics Co., Ltd.). Specifically, a 10 mm square resistive layer sample is placed on the sample stage of the penetration probe thermomechanical analyzer, and a penetration probe with a tip diameter of 1 mm is placed on the sample. A load of 70 gf is applied to the probe, and the sample is heated from room temperature at a rate of 2°C / min to measure the change in sample thickness. The heat resistance temperature is determined as the temperature at which the sample thickness becomes half of the sample thickness (initial thickness) when the load is applied to the sample.

[0027] The resistance layer 30 preferably contains, for example, a conductive material, which allows for easy adjustment of the through resistance value within the above range. The conductive material preferably contains at least one of a carbon material and a metal. The carbon material preferably contains at least one selected from the group consisting of carbon nanotubes, carbon black, graphene, and graphite. The carbon material content may be any amount that ensures the through resistance value within the above range, and is preferably 20 mass% or more, and more preferably 40 mass% or more, relative to the total mass of the resistance layer 30. Since the resistance layer 30 may be composed of a single carbon material, the upper limit of the carbon material content may be 100 mass%. Examples of metals include Cu, Ag, Fe, Zn, Ti, Ni, Cr, and alloys thereof. Among these, the metal preferably contains at least one selected from the group consisting of Ni, Cr, and Ni / Cr alloys. The content of the alloy containing Ni, Cr, or Ni / Cr may be any amount that ensures that the through resistance value falls within the above range, and is, for example, preferably 30 mass % or more, and more preferably 50 mass % or more, relative to the total mass of the resistance layer 30. Since the resistance layer 30 may be composed of a single material, such as an alloy containing Ni, Cr, or Ni / Cr, the upper limit of the content of the alloy containing Ni, Cr, or Ni / Cr may be 100 mass %. The use of carbon nanotubes, carbon black, graphene, graphite, an alloy containing Ni, Cr, or Ni / Cr may improve the heat resistance of the resistance layer 30 in some cases.

[0028] The resistance layer 30 preferably contains an insulating material. The insulating material preferably contains at least one of a ceramic material and a resin, for example, in order to improve the heat resistance or mechanical strength of the resistance layer 30. The content of the insulating material may be, for example, 20 mass % or more and 80 mass % or less with respect to the total mass of the resistance layer 30. Examples of the ceramic material include SiO ２ , Si ３ N ４ , Al ２ O ３ , ZrO ２ , MgO, TiO ２Among these, ceramic materials are preferred, especially Al, in that they further improve the heat resistance of the resistance layer 30. ２ O ３ and ZrO ２ It is preferable that the resin contains at least one of the following. Examples of the resin include phenolic resin, polyethylene, polypropylene, polystyrene, polybutadiene, epoxy resin, fluororesin, melamine resin, polyvinyl chloride, polymethyl methacrylate, polyamide, polyimide, polycarbonate, polyethylene terephthalate, polyethylene naphthalate, polyethersulfone, polyphenylene sulfide, and polyetherimide. Among these, it is preferable that the resin contains at least one selected from the group consisting of phenolic resin, epoxy resin, melamine resin, polytetrafluoroethylene, polyimide, and polypropylene, in order to further improve the mechanical strength of the heat-resistant layer 30.

[0029] The thickness of the resistance layer 30 is, for example, preferably 0.001 mm or more and 2.0 mm or less, and more preferably 0.01 mm or more and 1.0 mm or less. From the viewpoint of manufacturing in the crimping process of the outer can 16, it is preferable that the thickness of the resistance layer 30 be within the above range.

[0030] The positive electrode 11 includes, for example, a positive electrode current collector and a positive electrode composite layer provided on the positive electrode current collector. The positive electrode composite layer includes, for example, a positive electrode active material, a binder, a conductive material, etc. The positive electrode 11 is obtained, for example, by applying a positive electrode composite slurry including the positive electrode active material, the binder, the conductive material, etc., onto the positive electrode current collector and drying it to form a positive electrode composite layer on the positive electrode current collector, and then rolling the positive electrode composite layer. The positive electrode composite layer may be provided on one side of the positive electrode current collector or on both sides of the positive electrode current collector.

[0031] The positive electrode current collector may be a foil of a metal such as aluminum or an aluminum alloy that is stable within the potential range of the positive electrode, or a film having such a metal disposed on the surface thereof.

[0032] The positive electrode active material may be, for example, a lithium transition metal composite oxide containing transition metal elements such as Ni, Co, or Mn. Metal elements contained in the lithium transition metal composite oxide include Ni, Co, Mn, Al, Be, B, Na, Mg, Si, K, Ca, Sc, Ti, V, Cr, Fe, Cu, Zn, Ga, Sr, Y, Zr, Nb, Mo, In, Sn, Sb, Ba, Ta, W, Pb, and Bi. Among these, it is preferable to contain at least one of Ni, Co, and Mn. Examples of suitable composite oxides include lithium transition metal composite oxides containing Ni, Co, and Mn, and lithium transition metal composite oxides containing Ni, Co, and Al. One type of lithium transition metal composite oxide may be used alone, or multiple types may be used in combination.

[0033] The lithium transition metal composite oxide has, for example, a layered rock salt structure. Examples of the layered rock salt structure include a layered rock salt structure belonging to the space group R-3m and a layered rock salt structure belonging to the space group C2 / m. Among these, a layered rock salt structure belonging to the space group R-3m is preferred from the viewpoints of high capacity and stability of the crystal structure. The content of the positive electrode active material is, for example, 90% by mass or more and 99% by mass or less with respect to the mass of the positive electrode mixture layer. From the viewpoint of increasing the capacity of the battery, the density of the positive electrode mixture layer is preferably 3.3 g / cc or more, and, for example, 3.3 cc or more and 3.8 g / cc or less.

[0034] Examples of conductive materials contained in the positive electrode mixture layer include carbon black such as acetylene black and ketjen black, graphite, carbon nanotubes (CNT), carbon nanofibers, graphene, metal fibers, metal powder, and conductive whiskers. One type of conductive material may be used alone, or multiple types may be used in combination. The content of the conductive material may be, for example, 0.1% by mass or more and 5% by mass or less with respect to the total mass of the positive electrode mixture layer.

[0035] Examples of binders contained in the positive electrode mixture layer include fluorine-containing resins such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF), olefin resins such as polyethylene, polypropylene, ethylene-propylene-isoprene copolymer, and ethylene-propylene-butadiene copolymer, acrylic resins such as polyacrylonitrile (PAN), polyimide, polyamide, and ethylene-acrylic acid copolymer, styrene-butadiene copolymer (SBR), carboxymethyl cellulose (CMC) or a salt thereof, polyacrylic acid (PAA) or a salt thereof, polyvinyl alcohol (PVA), and polyethylene oxide (PEO). One type of binder may be used alone, or multiple types may be used in combination. The content of the binder may be 0.6% by mass or more and 1.5% by mass or less, based on the total mass of the positive electrode mixture layer.

[0036] The negative electrode 12 includes, for example, a negative electrode current collector and a negative electrode composite layer formed on the negative electrode current collector. The negative electrode current collector can be a foil of a metal, such as copper, that is stable within the potential range of the negative electrode, or a film with such a metal disposed on its surface. The negative electrode composite layer includes, for example, a negative electrode active material and a binder. The negative electrode 12 can be obtained, for example, by applying and drying a negative electrode composite slurry containing the negative electrode active material and the binder onto the negative electrode current collector to form a negative electrode composite layer on the negative electrode current collector, and then rolling the negative electrode composite layer. The negative electrode composite layer may be provided on one side of the negative electrode current collector, or on both sides of the negative electrode current collector.

[0037] The negative electrode active material may be, for example, a carbon material that reversibly absorbs and releases lithium ions. Examples of carbon materials that function as the negative electrode active material include graphite, such as natural graphite, artificial graphite, and mixtures thereof. The negative electrode active material may be an element that alloys with Li, such as Si or Sn, or a material containing such an element. Among these, Si-containing materials are preferred. Furthermore, lithium titanate, which has a higher charge / discharge potential relative to metallic lithium than carbon materials, may also be used as the negative electrode active material. The content of the negative electrode active material is, for example, 90% by mass or more and 99.5% by mass or less, based on the mass of the negative electrode mixture layer 32.

[0038] Examples of the binder include the same binders as those used in the positive electrode 11. One type of binder may be used alone, or multiple types may be used in combination. The content of the binder is, for example, 0.1 mass % or more and 5 mass % or less with respect to the total mass of the negative electrode mixture layer. Note that the negative electrode mixture layer may also contain a conductive material.

[0039] The separator 13 may be, for example, a porous sheet having ion permeability and insulating properties. Specific examples of porous sheets include a microporous thin film, a woven fabric, and a nonwoven fabric. Suitable materials for the separator include olefin-based resins such as polyethylene and polypropylene, and cellulose. The separator 13 may be a laminate having a cellulose fiber layer and a thermoplastic resin fiber layer such as an olefin-based resin. Alternatively, the separator 13 may be a multilayer separator including a polyethylene layer and a polypropylene layer, and a separator whose surface is coated with a material such as an aramid-based resin or ceramic may be used.

[0040] The present disclosure will be further described below with reference to examples, but the present disclosure is not limited to the following examples.

[0041] (Example 1) <Measurement of the penetration resistance value of the resistance layer> A resistance layer slurry containing 20 parts by mass of carbon black, 40 parts by mass of phenol resin, and 40 parts by mass of butyl carbitol as a dispersion medium was applied to the entire periphery along the edge of the upper surface of the sealing body, and then dried at 100°C for 24 hours to obtain a thickness of 1 mm, an outer diameter of 17 mm, an inner diameter of 13 mm, and an area of ​​94 mm. ２ An annular resistive layer of 1000 Ω was produced. The sealing body was fixed to a fixing jig, and with a pressure of 5 MPa applied from the top and bottom of the sealing body, two terminals (Hioki Corporation, pin-type leads 9772) electrically connected to a digital resistance meter (Hioki Corporation, RM3545A-1) were brought into contact with the bottom surface of the sealing body and the resistive layer, and the resistance value (Ω) was measured. This was taken as the actual resistance value. The resistance value was also measured in the same way for the sealing body before the resistive layer was produced, and this was taken as the reference resistance value. The through resistance value of the resistive layer was then calculated using the following formula. As a result, the through resistance value of the resistive layer was 2 Ω. Through resistance value (Ω) = actual resistance value - reference resistance value

[0042] <Battery Fabrication> Lithium cobalt oxide, which is a positive electrode active material, acetylene black, and polyvinylidene fluoride were mixed in a solid mass ratio of 98.4:1.0:0.6, and N-methylpyrrolidone (NMP) was used as a dispersion medium to prepare a positive electrode mixture slurry. The slurry was applied to both sides of a positive electrode current collector made of aluminum foil, and the coating was dried and then rolled using a rolling roller. In this way, a positive electrode having a positive electrode mixture layer formed on both sides of the positive electrode current collector was obtained.

[0043] A negative electrode composite slurry was prepared by mixing graphite, which is a negative electrode active material, carboxymethyl cellulose (CMC), and styrene-butadiene rubber (SBR) in a solids mass ratio of 98:1:1, and using water as a dispersion medium. The slurry was applied to both sides of a negative electrode current collector made of copper foil, and the coating was dried and then rolled using a rolling roller. In this way, a negative electrode was produced in which a negative electrode composite layer was formed on both sides of the negative electrode current collector.

[0044] Ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) were mixed in a volume ratio of 20:75:5. ６ was dissolved in the above solution to a concentration of 1.3 mol / L to prepare a non-aqueous electrolyte.

[0045] A positive electrode lead was attached to the positive electrode, and a negative electrode lead was attached to the negative electrode. The positive electrode, negative electrode, and polyethylene separator were then spirally wound around a cylindrical winding core, after which the winding core was removed to obtain a wound electrode assembly. After insulating plates were placed on the top and bottom of the electrode assembly, the negative electrode lead was welded to the inner bottom surface of a bottomed cylindrical outer can, and the positive electrode lead was welded to the underside of a sealing member, thereby housing the electrode assembly inside the outer can. A nonaqueous electrolyte was then injected into the outer can under reduced pressure, and the outer can was crimped to the sealing member via a gasket, and the opening of the outer can was sealed with the sealing member to obtain a battery. The sealing member used was the sealing member provided with the annular resistive layer described above. That is, in the battery of Example 1, a resistive layer having a through resistance value of 2 Ω was disposed between the top surface of the sealing member and a gasket located between the top surface of the sealing member and the tip of the end of the outer can facing the top surface of the sealing member on the opening side.

[0046] (Example 2) <Measurement of the penetration resistance value of the resistive layer> A sheet formed by vacuum-depositing carbon black on a copper substrate was cut into a circular sheet (thickness 1 mm, outer diameter 17 mm, inner diameter 13 mm, area 94 mm ２ ) was prepared. This annular sheet was attached as a resistive layer along the edge of the upper surface of the sealing body. Using this sealing body, the penetration resistance value of the resistive layer was determined in the same manner as in Example 1. As a result, the penetration resistance value of the resistive layer was 3 kΩ. Then, using the sealing body with a resistive layer having a penetration resistance value of 3 kΩ arranged thereon, a battery was prepared in the same manner as in Example 1. That is, in the battery of Example 2, a resistive layer having a penetration resistance value of 3 kΩ was arranged between the upper surface of the sealing body and the gasket located between the upper surface of the sealing body and the end tip on the opening side of the outer can.

[0047] Comparative Example 1 A battery was fabricated in the same manner as in Example 1, except that a sealing body without a resistive layer was used.

[0048] Comparative Example 2 A heat-resistant inorganic adhesive, Aron Ceramic (Aron Ceramic C, manufactured by Toa Gosei Co., Ltd.), was applied to the entire periphery along the edge of the top surface of the sealing body to form a seal with a thickness of 1 mm, an outer diameter of 17 mm, an inner diameter of 13 mm, and an area of ​​94 mm. ２ An annular resistive layer having a through resistance of 300 MΩ or more was fabricated. Using this sealing body, the through resistance value of the resistive layer was determined in the same manner as in Example 1. As a result, the through resistance value of the resistive layer was found to be 300 MΩ or more. Then, using the sealing body in which the resistive layer having a through resistance value of 300 MΩ or more was disposed, a battery was fabricated in the same manner as in Example 1. That is, in the battery of Comparative Example 2, a resistive layer having a through resistance value of 300 MΩ was disposed between the top surface of the sealing body and the tip of the end of the outer can on the opening side, and the top surface of the sealing body.

[0049] [External Short-Circuit Test] The batteries of each Example and Comparative Example were charged at a constant current of 1500 mA in an environment of 25°C until the battery voltage reached 4.3 V. Then, in an environment of 25°C, the positive and negative electrodes of each charged battery were externally short-circuited with a short-circuit resistance of 8 mΩ. 20 seconds after the external short-circuit, the circuit was interrupted and the short circuit was eliminated. The temperature of the battery surface after the external short-circuit was measured. The battery voltage after the external short-circuit was also monitored. The results are shown in Table 1.

[0050]

[0051] In Comparative Example 1, in which no resistive layer was disposed between the top surface of the sealing body and the end tip of the outer can on the opening side, gasket melting was confirmed after the short circuit test, and the battery temperature reached 500°C or higher. Note that the battery voltage in Comparative Example 1 could not be monitored. Also, in Comparative Example 2, in which a 300 MΩ resistive layer was disposed between the top surface of the sealing body and the end tip of the outer can on the opening side, gasket melting was confirmed after the external short circuit test. However, the battery temperature after the short circuit test was below 500°C, and the increase in battery temperature was suppressed. However, the battery voltage remained around 4.08 V, and the battery voltage hardly decreased. This is presumably because the 300 MΩ resistive layer functioned as an insulating layer even after the gasket melted. Also, in Examples 1 and 2, in which a resistive layer having a 2 Ω or 3 kΩ through resistance was disposed between the top surface of the sealing body and the end tip of the outer can on the opening side, gasket melting was confirmed after the external short circuit test. However, the battery temperature after the short circuit test was below 500°C, and the increase in battery temperature was suppressed. Furthermore, a decrease in the battery voltage was confirmed after the short circuit test, with the battery voltage being 0.01 V or less. This is presumably because the resistive layer having the above-mentioned penetration resistance value reduces the short circuit current flowing between the top surface of the sealing body and the tip of the end of the outer can on the opening side, while ensuring a certain degree of electrical continuity between the outer can and the sealing body.

[0052] The present disclosure is further described by the following embodiments. Configuration 1: A battery comprising: a cylindrical outer can with a bottom, having an opening, and housing an electrode assembly; a sealing body covering the opening of the outer can; an insulating layer disposed between the outer can and the sealing body; and a resistive layer having a through resistance value of 0.05 Ω or more and 10 kΩ or less, disposed between a tip of an end of the outer can on the opening side and an upper surface of the sealing body facing the tip of the end. Configuration 2: The battery according to Configuration 1, wherein the resistive layer is disposed between the insulating layer and the upper surface of the sealing body. Configuration 3: The battery according to Configuration 1 or 2, wherein the resistive layer is disposed inside the insulating layer. Configuration 4: The battery according to any one of Configurations 1 to 3, wherein the through resistance value of the resistive layer is 2 Ω or more and 3 kΩ or less. Configuration 5: The battery according to any one of Configurations 1 to 4, wherein the resistive layer contains a conductive material. Configuration 6: The battery according to Configuration 5, wherein the resistive layer contains an insulating material. Configuration 7: The battery according to configuration 5 or 6, wherein the conductive material comprises at least one of a carbon material and a metal. Configuration 8: The battery according to configuration 7, wherein the carbon material comprises at least one selected from the group consisting of carbon nanotubes, carbon black, graphene, and graphite. Configuration 9: The battery according to configuration 7, wherein the metal comprises at least one selected from the group consisting of Ni, Cr, and an alloy containing Ni / Cr. Configuration 10: The battery according to configuration 6, wherein the insulating material comprises at least one of a ceramic material and a resin. Configuration 11: The ceramic material is Al ２ O ３ and ZrO ２ The battery of configuration 10, comprising at least one of the following: Configuration 12: The battery of configuration 10 or 11, wherein the resin comprises at least one selected from the group consisting of phenolic resin, epoxy resin, melamine resin, polytetrafluoroethylene, polyimide, and polypropylene. Configuration 13: The battery of any one of configurations 1 to 12, wherein the thickness of the resistive layer is 0.001 mm or more and 2.0 mm or less.

[0053] REFERENCE SIGNS LIST 10 battery, 11 positive electrode, 12 negative electrode, 13 separator, 14 electrode body, 15 battery case, 16 outer can, 16a end tip, 17 sealing body, 18, 19 insulating plate, 20 positive electrode lead, 21 negative electrode lead, 22 protruding portion, 23 filter, 24 lower valve body, 25 insulating member, 26 upper valve body, 27 cap, 28 gasket, 30 resistance layer.

Claims

1. A battery comprising: a cylindrical outer can with a bottom that has an opening and houses an electrode assembly; a sealing body that covers the opening of the outer can; an insulating layer that is disposed between the outer can and the sealing body; and a resistive layer that has a through resistance value of 0.05 Ω or more and 10 kΩ or less and that is disposed between the tip of the end of the outer can on the opening side and the upper surface of the sealing body that faces the tip of the end.

2. The battery according to claim 1, wherein the resistive layer is disposed between the insulating layer and the upper surface of the sealing body.

3. The battery of claim 1, wherein the resistive layer is disposed within the insulating layer.

4. The battery according to any one of claims 1 to 3, wherein the through resistance value of the resistance layer is 2 Ω or more and 3 kΩ or less.

5. The battery according to any one of claims 1 to 3, wherein the resistive layer comprises a conductive material.

6. The battery of claim 5, wherein the resistive layer comprises an insulating material.

7. The battery according to claim 5, wherein the conductive material includes at least one of a carbon material and a metal.

8. The battery of claim 7, wherein the carbon material comprises at least one selected from the group consisting of carbon nanotubes, carbon black, graphene, and graphite.

9. The battery of claim 7, wherein the metal comprises at least one selected from the group consisting of Ni, Cr, and an alloy comprising Ni / Cr.

10. The battery according to claim 6, wherein the insulating material includes at least one of a ceramic material and a resin.

11. The ceramic material is Al ２ O ３ and ZrO ２ 11. The battery of claim 10, comprising at least one of:

12. The battery according to claim 10, wherein the resin comprises at least one selected from the group consisting of phenolic resin, epoxy resin, melamine resin, polytetrafluoroethylene, polyimide, and polypropylene.

13. The battery according to any one of claims 1 to 3, wherein the thickness of the resistive layer is 0.001 mm or more and 2.0 mm or less.

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