WO2022163479A1 - 二次電池、電子機器及び電動工具 - Google Patents
二次電池、電子機器及び電動工具 Download PDFInfo
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- WO2022163479A1 WO2022163479A1 PCT/JP2022/001898 JP2022001898W WO2022163479A1 WO 2022163479 A1 WO2022163479 A1 WO 2022163479A1 JP 2022001898 W JP2022001898 W JP 2022001898W WO 2022163479 A1 WO2022163479 A1 WO 2022163479A1
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- negative electrode
- electrode active
- active material
- positive electrode
- metal
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Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/058—Construction or manufacture
- H01M10/0587—Construction or manufacture of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/04—Construction or manufacture in general
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/04—Construction or manufacture in general
- H01M10/0431—Cells with wound or folded 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
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
-
- 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
- H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
- H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/64—Carriers or collectors
- H01M4/66—Selection of materials
-
- 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
- H01M50/10—Primary casings; Jackets or wrappings
-
- 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
- H01M50/10—Primary casings; Jackets or wrappings
- H01M50/116—Primary casings; Jackets or wrappings characterised by the material
- H01M50/117—Inorganic material
- H01M50/119—Metals
-
- 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
-
- 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
-
- 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
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
Definitions
- the present invention relates to secondary batteries, electronic devices, and power tools.
- Lithium-ion batteries are also being developed for applications that require high output, such as power tools and automobiles.
- One method of achieving high power is high rate discharge, in which a relatively large current is drawn from the battery. Since high-rate discharge requires a large current, it is desirable to reduce the internal resistance of the battery.
- Patent Literature 1 describes a cylindrical battery with a so-called tableless structure that does not have a tab for leading the power of the battery to the outside.
- Patent Document 2 describes an inspection apparatus that inspects the winding misalignment state of a wound inspection object by image processing.
- an inspection process is performed to inspect the presence or absence of winding misalignment for lithium-ion batteries.
- winding misalignment is a state in which the positive electrode active material coating portion coated with the positive electrode active material exceeds the range of the negative electrode active material coating portion coated with the negative electrode active material.
- an inspection step is performed to detect a state in which the positive electrode active material covering portion and the negative electrode active material covering portion do not face each other.
- one of the objects of the present invention is to provide a secondary battery having a configuration that allows inspection of winding misalignment, and an electronic device and an electric tool having the secondary battery.
- the present invention A secondary battery in which an electrode winding body in which a strip-shaped positive electrode and a strip-shaped negative electrode are laminated with a separator interposed therebetween, and a positive electrode current collector plate and a negative electrode current collector plate are housed in a battery can,
- the positive electrode has a positive electrode active material coated portion coated with a positive electrode active material layer and a positive electrode active material uncoated portion on a strip-shaped positive electrode foil
- the negative electrode includes a strip-shaped negative electrode foil coated with a negative electrode active material layer, a negative electrode active material uncoated portion extending at least in the longitudinal direction of the negative electrode foil, a negative electrode active material coated portion and the negative electrode.
- the positive electrode active material non-coated portion is joined to the positive electrode current collector plate at one end of the electrode winding body
- the negative electrode active material non-coated portion is joined to the negative electrode current collector plate at the other end of the electrode winding body
- the insulating layer is a secondary battery containing a metal or metal compound having a higher X-ray shielding effect than specified.
- FIG. 1 is a cross-sectional view of a lithium ion battery according to one embodiment.
- 2A and 2B are diagrams for explaining a positive electrode according to one embodiment.
- 3A and 3B are diagrams for explaining a negative electrode according to one embodiment.
- FIG. 4 is a diagram showing a positive electrode, a negative electrode, and a separator before winding.
- FIG. 5A is a plan view of a positive current collector according to one embodiment
- FIG. 5B is a plan view of a negative current collector according to one embodiment.
- 6A to 6F are diagrams illustrating the assembly process of a lithium ion battery according to one embodiment.
- FIG. 7 is a diagram for explaining the action of the insulating layer and the effect obtained by providing the insulating layer according to one embodiment.
- FIG. 8 is a diagram for explaining Comparative Example 1.
- FIG. 9 is a diagram for explaining Comparative Example 1.
- FIG. 10 is a connection diagram used for explaining a battery pack as an application example of the present invention.
- FIG. 11 is a connection diagram used for explaining a power tool as an application example of the present invention.
- FIG. 12 is a connection diagram used for explaining an electric vehicle as an application example of the present invention.
- FIG. 1 is a schematic cross-sectional view of a lithium ion battery 1.
- the lithium ion battery 1 is, for example, a cylindrical lithium ion battery 1 in which an electrode winding body 20 is housed inside a battery can 11 as shown in FIG.
- the lithium ion battery 1 has a roughly cylindrical battery can 11 , and inside the battery can 11 , a pair of insulating plates 12 and 13 and an electrode winding 20 are provided.
- the lithium ion battery 1 may further include, for example, one or more of a thermal resistance (PTC) element and a reinforcing member inside the battery can 11 .
- PTC thermal resistance
- the battery can 11 is mainly a member that houses the electrode winding body 20 .
- the battery can 11 is, for example, a cylindrical container that is open at one end and closed at the other end. That is, the battery can 11 has one open end surface (open end surface 11N).
- the battery can 11 contains, for example, one or more of metal materials such as iron, aluminum, and alloys thereof.
- the surface of the battery can 11 may be plated with, for example, one or more of metal materials such as nickel.
- the insulating plates 12 and 13 are disk-shaped having surfaces substantially perpendicular to the central axis of the electrode winding body 20 (a direction passing through substantially the center of the end face of the electrode winding body 20 and parallel to the Z axis in FIG. 1). It is a board of Also, the insulating plates 12 and 13 are arranged, for example, so as to sandwich the electrode winding body 20 between them.
- the battery lid 14 and the safety valve mechanism 30 are crimped to the open end surface 11N of the battery can 11 via a gasket 15 to form a crimp structure 11R (crimp structure).
- crimp structure 11R crimp structure
- the battery lid 14 is a member that mainly closes the open end face 11N of the battery can 11 in a state where the electrode wound body 20 and the like are housed inside the battery can 11 .
- the battery lid 14 contains, for example, the same material as the battery can 11 forming material.
- a central region of the battery lid 14 protrudes, for example, in the +Z direction.
- the area (peripheral area) of the battery lid 14 other than the central area is in contact with the safety valve mechanism 30, for example.
- Gasket 15 is a member that is mainly interposed between battery can 11 (bent portion 11P) and battery lid 14 to seal the gap between bent portion 11P and battery lid 14 .
- the surface of the gasket 15 may be coated with, for example, asphalt.
- the safety valve mechanism 30 mainly releases the internal pressure by releasing the sealed state of the battery can 11 as necessary when the internal pressure (internal pressure) of the battery can 11 increases.
- the cause of the rise in the internal pressure of the battery can 11 is, for example, the gas generated due to the decomposition reaction of the electrolytic solution during charging and discharging.
- a strip-shaped positive electrode 21 and a strip-shaped negative electrode 22 are laminated with a separator 23 interposed therebetween, and are spirally wound and impregnated with an electrolytic solution. It's settled.
- the positive electrode 21 is formed by forming a positive electrode active material layer 21B on one side or both sides of a positive electrode foil 21A, and the material of the positive electrode foil 21A is, for example, a metal foil made of aluminum or an aluminum alloy.
- the negative electrode 22 is formed by forming a negative electrode active material layer 22B on one side or both sides of a negative electrode foil 22A, and the material of the negative electrode foil 22A is, for example, metal foil made of nickel, nickel alloy, copper, or copper alloy.
- the separator 23 is a porous and insulating film that electrically insulates the positive electrode 21 and the negative electrode 22 while enabling movement of substances such as ions and electrolytic solution.
- FIG. 2A is a front view of the positive electrode 21 before winding
- FIG. 2B is a side view of the positive electrode 21 in FIG. 2A
- the positive electrode 21 has a portion (dotted portion) covered with the positive electrode active material layer 21B on one main surface and the other main surface of the positive electrode foil 21A, and the portion not covered with the positive electrode active material layer 21B. It has a positive electrode active material uncoated portion 21C.
- the portion covered with the positive electrode active material layer 21B is appropriately referred to as the positive electrode active material covered portion 21B.
- the positive electrode foil 21A may have a configuration in which the positive electrode active material covering portion 21B is provided on one main surface.
- FIG. 3A is a front view of the negative electrode 22 before winding
- FIG. 3B is a side view of the negative electrode 22 in FIG. 3A.
- the negative electrode 22 has a portion (dotted portion) covered with the negative electrode active material layer 22B on one main surface and the other main surface of the negative electrode foil 22A, and the portion not covered with the negative electrode active material layer 22B. It has a certain negative electrode active material uncoated portion 22C.
- the portion covered with the negative electrode active material layer 22B is appropriately referred to as the negative electrode active material covered portion 22B.
- the negative electrode foil 22A may have a configuration in which the negative electrode active material covering portion 22B is provided on one main surface of the negative electrode foil 22A.
- the negative electrode active material uncoated portion 22C includes, for example, a first negative electrode active material uncoated portion 221A extending in the longitudinal direction of the negative electrode 22 (X-axis direction in FIG. A second negative electrode active material non-coated portion 221B extending in the lateral direction of the negative electrode 22 (the Y-axis direction in FIG. 3; also referred to as the width direction as appropriate) on the winding start side of the negative electrode 22, and the winding of the negative electrode 22 It has a third negative electrode active material uncovered portion 221C extending in the lateral direction of the negative electrode 22 (the Y-axis direction in FIG. 3) on the rotation termination side.
- a first negative electrode active material uncoated portion 221A extending in the longitudinal direction of the negative electrode 22 (X-axis direction in FIG.
- a second negative electrode active material non-coated portion 221B extending in the lateral direction of the negative electrode 22 (the Y-axis direction in FIG. 3; also referred to as the width direction as appropriate)
- the negative electrode 22 further has an insulating layer 22D (the gray portion in FIG. 3).
- the insulating layer 22D is provided between the negative electrode active material covered portion 22B and the first negative electrode active material non-covered portion 221A. Details of the insulating layer 22D will be described later.
- the electrode winding body 20 is configured such that the positive electrode active material uncoated portion 21C and the first negative electrode active material uncoated portion 221A face opposite directions to each other, and the separator 23 are stacked and wound.
- a through hole 26 is provided in the center of the electrode winding body 20 .
- the through-hole 26 is a hole formed substantially at the center of the laminate in which the positive electrode 21 , the negative electrode 22 and the separator 23 are laminated.
- the through-hole 26 is used as a hole for inserting a rod-shaped welding tool (hereinafter referred to as a welding rod as appropriate) or the like in the process of assembling the lithium ion battery 1 .
- FIG. 4 shows an example of the structure before winding in which the positive electrode 21, the negative electrode 22 and the separator 23 are laminated.
- the positive electrode 21 includes an insulating layer 101 (the gray area in FIG. 4) covering the boundary between the positive electrode active material covered portion 21B (the portion sparsely dotted in FIG. 4) and the positive electrode active material non-coated portion 21C. further has The length of the insulating layer 101 in the width direction is, for example, about 3 mm.
- the insulating layer 101 covers the entire region of the positive electrode active material uncovered portion 21C facing the negative electrode active material covered portion 22B with the separator 23 interposed therebetween.
- the insulating layer 101 has the effect of reliably preventing an internal short circuit of the lithium ion battery 1 when foreign matter enters between the negative electrode active material covered portion 22B and the positive electrode active material uncovered portion 21C. Moreover, the insulating layer 101 absorbs the impact when the lithium ion battery 1 is impacted, and has the effect of reliably preventing bending of the positive electrode active material uncoated portion 21C and short-circuiting with the negative electrode 22 .
- the length in the width direction of the positive electrode active material uncoated portion 21C is D5, and the length in the width direction of the first negative electrode active material uncoated portion 221A is D6.
- the length of the portion where the positive electrode active material uncoated portion 21C protrudes from one end of the separator 23 in the width direction is defined as D7, and the insulating layer 22E and the first negative electrode active material uncoated portion 221A extend from the other end of the separator 23 in the width direction.
- the positive electrode foil 21A and the positive electrode active material uncoated portion 21C are made of, for example, aluminum, and the negative electrode foil 22A and the negative electrode active material uncoated portion 22C are made of, for example, copper.
- the positive electrode active material uncoated portion 21C is generally softer (lower Young's modulus) than the negative electrode active material uncoated portion 22C. Therefore, in one embodiment, it is more preferable that D5>D6 and D7>D8. Then, when the first negative electrode active material uncoated portion 221A) is bent, the height of the bent portion measured from the tip of the separator 23 may be about the same for the positive electrode 21 and the negative electrode 22 .
- the positive electrode active material uncoated portion 21C is bent and overlaps appropriately, laser welding of the positive electrode active material uncoated portion 21C and the positive electrode current collector plate 24 in the manufacturing process of the lithium ion battery 1 (details will be described later) is performed. can be easily joined.
- the first negative electrode active material uncoated portion 221A is bent and overlaps appropriately, laser welding of the first negative electrode active material uncoated portion 221A and the negative electrode current collector plate 25 in the manufacturing process of the lithium ion battery 1 is possible. can be easily joined.
- the positive electrode collector plate 24 is arranged on one end surface 41 of the electrode wound body 20
- the negative electrode collector plate is arranged on the other end surface 42 of the electrode wound body 20 .
- a collector plate 25 is arranged.
- the positive electrode current collector plate 24 and the positive electrode active material uncoated portion 21C present on the end face 41 are welded at multiple points, and the negative electrode current collector plate 25 and the first negative electrode active material uncoated portion present on the end face 42 are welded at multiple points.
- welding 221A at multiple points the internal resistance of the lithium-ion battery 1 is kept low, enabling high-rate discharge.
- FIGS. 5A and 5B An example of a current collector plate is shown in FIGS. 5A and 5B.
- FIG. 5A shows the positive collector plate 24 and FIG. 5B shows the negative collector plate 25 .
- the positive collector plate 24 and the negative collector plate 25 are accommodated in the battery can 11 (see FIG. 1).
- the material of the positive electrode current collector plate 24 is, for example, a metal plate made of aluminum or an aluminum alloy alone or a composite material
- the material of the negative electrode current collector plate 25 is, for example, nickel, a nickel alloy, copper, or a copper alloy alone. Or a metal plate made of composite material.
- the shape of the positive electrode current collector plate 24 is such that a flat fan-shaped fan-shaped portion 31 is attached to a rectangular band-shaped portion 32 .
- a hole 35 is formed near the center of the fan-shaped portion 31 , and the position of the hole 35 corresponds to the through hole 26 .
- the portion indicated by dots in FIG. 5A is an insulating portion 32A in which an insulating tape is attached to the belt-like portion 32 or an insulating material is applied. This is the connecting portion 32B.
- the strip-shaped portion 32 is less likely to come into contact with the portion of the negative electrode potential. good.
- the charge/discharge capacity can be increased by increasing the width between the positive electrode 21 and the negative electrode 22 by an amount corresponding to the thickness of the insulating portion 32A.
- the shape of the negative electrode current collector plate 25 is almost the same as that of the positive electrode current collector plate 24, but the shape of the strip portion is different.
- the strip portion 34 of the negative electrode current collector plate in FIG. 5B is shorter than the strip portion 32 of the positive electrode current collector plate 24, and there is no portion corresponding to the insulating portion 32A.
- the band-shaped portion 34 is provided with a plurality of circular protrusions (projections) 37 indicated by circles. During resistance welding, the current concentrates on the protrusion 37 , melting the protrusion 37 and welding the belt-like portion 34 to the bottom of the battery can 11 .
- the negative collector plate 25 has a hole 36 near the center of the fan-shaped portion 33 , and the position of the hole 36 corresponds to the through hole 26 . Since the fan-shaped portion 31 of the positive electrode current collector plate 24 and the fan-shaped portion 33 of the negative electrode current collector plate 25 are fan-shaped, they partially cover the end surfaces 41 and 42 . By not covering the entire lithium ion battery 1, the electrolytic solution can be smoothly penetrated into the electrode winding body 20 when assembling the lithium ion battery 1, and the lithium ion battery 1 is in an abnormally high temperature state or an overcharged state. It is possible to make it easier to release the gas that is sometimes generated to the outside of the lithium ion battery 1 .
- the positive electrode active material layer 21B contains at least a positive electrode material (positive electrode active material) capable of intercalating and deintercalating lithium, and may further contain a positive electrode binder, a positive electrode conductor, and the like.
- the positive electrode material is preferably a lithium-containing composite oxide or a lithium-containing phosphate compound.
- the lithium-containing composite oxide has, for example, a layered rock salt type or spinel type crystal structure.
- a lithium-containing phosphate compound has, for example, an olivine-type crystal structure.
- the positive electrode binder contains synthetic rubber or a polymer compound.
- Synthetic rubbers include styrene-butadiene-based rubber, fluorine-based rubber, and ethylene propylene diene.
- Polymer compounds include polyvinylidene fluoride (PVDF) and polyimide.
- the positive electrode conductor is a carbon material such as graphite, carbon black, acetylene black, or ketjen black.
- the positive electrode conductor may be a metal material or a conductive polymer.
- the surface of the negative electrode foil 22A that constitutes the negative electrode 22 is preferably roughened in order to improve adhesion with the negative electrode active material layer 22B.
- the negative electrode active material layer 22B contains at least a negative electrode material (negative electrode active material) capable of intercalating and deintercalating lithium, and may further contain a negative electrode binder, a negative electrode conductor, and the like.
- the negative electrode material includes, for example, a carbon material.
- the carbon material is graphitizable carbon, non-graphitizable carbon, graphite, low-crystalline carbon, or amorphous carbon.
- the shape of the carbon material is fibrous, spherical, granular or scaly.
- the negative electrode material includes, for example, a metal-based material.
- metallic materials include Li (lithium), Si (silicon), Sn (tin), Al (aluminum), Zr (zinc), and Ti (titanium).
- Metallic elements form compounds, mixtures, or alloys with other elements, examples of which include silicon oxide (SiO x (0 ⁇ x ⁇ 2)), silicon carbide (SiC), or an alloy of carbon and silicon , lithium titanate (LTO).
- the separator 23 is a porous film containing resin, and may be a laminated film of two or more kinds of porous films. Resins include polypropylene and polyethylene. The separator 23 may contain a resin layer on one side or both sides of a porous membrane as a base layer. This is because the adhesion of the separator 23 to each of the positive electrode 21 and the negative electrode 22 is improved, so that distortion of the wound electrode body 20 is suppressed.
- the resin layer contains resin such as PVDF.
- resin such as PVDF.
- a solution in which a resin is dissolved in an organic solvent is applied to the substrate layer, and then the substrate layer is dried.
- the base layer may be dried after the base layer is immersed in the solution.
- the resin layer preferably contains inorganic particles or organic particles from the viewpoint of improving heat resistance and battery safety. Types of inorganic particles include aluminum oxide, aluminum nitride, aluminum hydroxide, magnesium hydroxide, boehmite, talc, silica, mica, and the like.
- a surface layer containing inorganic particles as a main component and formed by a sputtering method, an ALD (atomic layer deposition) method, or the like may be used instead of the resin layer.
- the electrolytic solution contains a solvent and an electrolyte salt, and may further contain additives and the like as necessary.
- the solvent is a non-aqueous solvent such as an organic solvent, or water.
- An electrolytic solution containing a non-aqueous solvent is called a non-aqueous electrolytic solution.
- Non-aqueous solvents include cyclic carbonates, chain carbonates, lactones, chain carboxylates, nitriles (mononitriles), and the like.
- a representative example of the electrolyte salt is a lithium salt, but salts other than the lithium salt may be included.
- Lithium salts include lithium hexafluorophosphate ( LiPF6 ), lithium tetrafluoroborate ( LiBF4 ), lithium perchlorate (LiClO4), lithium methanesulfonate ( LiCH3SO3 ) , trifluoromethanesulfonic acid.
- Lithium (LiCF 3 SO 3 ) dilithium hexafluorosilicate (Li 2 SF 6 ), and the like.
- a mixture of these salts can also be used, and among them, a mixture of LiPF 6 and LiBF 4 is preferably used from the viewpoint of improving battery characteristics.
- the content of the electrolyte salt is not particularly limited, it is preferably 0.3 mol/kg to 3 mol/kg with respect to the solvent.
- the insulating layer 22D contains resin such as PVDF, for example.
- the insulating layer 22D may further contain inorganic particles or organic particles. Examples of inorganic particles include those containing one or more of aluminum oxide, aluminum nitride, aluminum hydroxide, magnesium hydroxide, boehmite, talc, silica, mica, and the like.
- the negative electrode active material covering portion 22B and the insulating layer 22D are provided on both sides of the negative electrode foil 22A.
- the insulating layer 22D exists between the first negative electrode active material uncovered portion 221A extending in the longitudinal direction (X-axis direction) of the negative electrode 22 and the negative electrode active material covered portion 22D. More specifically, the insulating layer 22D exists along the boundary between the first negative electrode active material uncovered portion 221A extending in the longitudinal direction (X-axis direction) of the negative electrode 22 and the negative electrode active material covered portion 22D. is doing.
- the thickness of the insulating layer 22D is less than or equal to the thickness of the negative electrode active material covering portion 22B.
- a configuration in which the negative electrode active material covering portion 22B and the insulating layer 22D are provided on one main surface of the negative electrode foil 22A may be employed.
- the negative electrode active material coating portion 22B may be provided on both surfaces of the negative electrode foil 22A, and only the insulating layer 22D may be provided on one main surface of the negative electrode foil 22A.
- the insulating layer 22D contains a metal or metal compound with a higher X-ray shielding effect than a predetermined value.
- the insulating layer 22D is made of a metal having a higher X-ray shielding effect than the metal (main component metal) constituting the negative electrode foil 22A, or a metal having a higher X-ray shielding effect than the metal (main component metal) constituting the negative electrode foil 22A.
- the insulating layer 22D contains particles of the above metal or particles of the above metal compound.
- the metal having a higher X-ray shielding effect than the metal forming the negative electrode foil 22A is, for example, one or more selected from the group consisting of tungsten (W), iridium (Ir), platinum (Pt), and gold (Au).
- the metal compound containing a metal having a higher X-ray shielding effect than the metal forming the negative electrode foil 22A is one or more selected from the group consisting of metal oxides, metal sulfate compounds, and metal carbonate compounds.
- the metal oxide is, for example, one or more selected from the group consisting of yttrium oxide, hafnium oxide, tantalum pentoxide, and tungsten oxide.
- the metal sulfate compound is one or more selected from the group consisting of barium sulfate and strontium sulfate.
- the metal carbonate compound is strontium carbonate.
- the positive electrode active material is applied to the surface of the strip-shaped positive electrode foil 21A to form the positive electrode active material coating portion 21B, and the negative electrode active material is coated onto the surface of the strip-shaped negative electrode foil 22A, which is used as the negative electrode active material.
- the material covering portion 22B is used.
- a positive electrode active material non-coated portion 21C not coated with a positive electrode active material is provided on one end side in the width direction of the positive electrode foil 21A, and a negative electrode active material non-coated portion 21C not coated with a negative electrode active material is provided on the negative electrode foil 22A.
- Covered portions 22C (first negative electrode active material uncovered portion 221A, second negative electrode active material uncovered portion 221B, and third negative electrode active material uncovered portion 221C) were provided.
- the insulating layer 22D was provided when the negative electrode active material covering portion 22B was provided. Next, processes such as drying were performed on the positive electrode 21 and the negative electrode 22 .
- the positive electrode active material uncoated portion 21C and the negative electrode active material uncoated portion 22C are stacked in opposite directions with the separator 23 interposed therebetween, and spirally wound so as to form a through hole 26 on the central axis.
- An electrode winding body 20 such as 6A was produced.
- FIG. 6B A groove 43 was made.
- a thin flat plate for example, a thickness of 0.5 mm
- the groove 43 extends, for example, from the outer edges 27 , 28 of the end faces 41 , 42 respectively to the through hole 26 .
- the number and arrangement of the grooves 43 shown in FIG. 6B are merely examples, and are not limited to the illustrated example.
- the same pressure is simultaneously applied to the end surfaces 41 and 42 from both electrode sides in a substantially vertical direction, and the positive electrode active material uncoated portion 21C and the negative electrode active material uncoated portion 22C (in this example, the first The negative electrode active material non-coated portion 221A) was bent toward the central axis of the winding structure, and the end surfaces 41 and 42 were formed to be flat surfaces.
- a load is applied by a flat plate surface or the like so that the positive electrode active material uncoated portion 21C on the end surface 41 and the first negative electrode active material uncoated portion 221A on the end surface 42 overlap each other toward the central axis. added.
- the fan-shaped portion 31 of the positive electrode collector plate 24 was laser-welded to the end surface 41
- the fan-shaped portion 33 of the negative electrode collector plate 25 was laser-welded to the end surface 42 to join them.
- the strip-shaped portion 32 of the positive electrode current collector plate 24 and the strip-shaped portion 34 of the negative electrode current collector plate 25 are bent, and the insulating plate 12 is attached to the positive electrode current collector plate 24 and the insulating plate is attached to the negative electrode current collector plate 25 .
- 13 is attached, the electrode winding body 20 assembled as described above is inserted into the battery can 11 shown in FIG. welded to. After the electrolytic solution was injected into the battery can 11, it was sealed with a gasket 15 and a battery lid 14 as shown in FIG. 6F. Lithium ion battery 1 was produced as described above.
- an inspection process for inspecting winding misalignment was performed on the manufactured lithium ion battery 1 .
- the inspection process was performed by, for example, irradiating the lithium ion battery 1 with X-rays using an X-ray irradiation device and analyzing the resulting X-ray image.
- an X-ray irradiation apparatus was used to sequentially irradiate the positive electrode side and the negative electrode side of the lithium ion battery 1 with X-rays, thereby performing the inspection process. Based on the change in the contrast of the X-ray image (X-ray transmission image) obtained by this, the presence or absence of winding misalignment was inspected.
- the presence or absence of winding misalignment means the presence or absence of a state in which the positive electrode active material coating portion 21B exceeds the range of the negative electrode active material coating portion 22B coated with the negative electrode active material. It means the presence or absence of a state not facing the material covering portion 22B.
- winding misalignment was confirmed, it was treated as a defective lithium ion battery 1 .
- the positive electrode side of the lithium ion battery 1 means a region including the end face 41 among both end faces of the electrode winding body 20 having a substantially cylindrical shape.
- the negative electrode side of the electrode winding body 20 means a region including the end face 42 among both end faces of the electrode winding body 20 having a substantially cylindrical shape.
- the insulating plate 12 and the insulating plate 13 may be insulating tapes.
- the joining method may be a method other than laser welding.
- the groove 43 remains in the flat surface even after the positive electrode active material uncoated portion 21C and the negative electrode active material uncoated portion 22C are bent, and the portion without the groove 43 is the positive electrode current collector plate 24 or the negative electrode current collector. Although it is joined to the plate 25 , the groove 43 may be joined to a part of the positive collector plate 24 or the negative collector plate 25 .
- the “flat surface” in this specification means not only a completely flat surface but also a predetermined portion (for example, to the extent that the first negative electrode active material non-coated portion 221A) and the negative electrode current collector plate 25 can be bonded, it also includes a surface having some unevenness or surface roughness.
- FIG. 7 is a diagram showing a cross section of the electrode winding body 20 cut along the cutting line XA-XA in FIG.
- FIG. 7 shows one layer each of the positive electrode 21, the negative electrode 22, and the separator 23.
- the contrast of the X-ray image obtained when the positive electrode side of the lithium ion battery 1 is irradiated with X-rays is schematically shown on the upper left side of the cross-sectional view.
- the contrast of an X-ray image obtained when the negative electrode side is irradiated with X-rays is schematically shown on the lower left side of the cross-sectional view.
- Boundary B1 and boundary B2 can be detected based on a change in the contrast of the X-ray image due to irradiation with X-rays (locations denoted by reference sign AA in FIG. 7).
- boundary B1 is also the edge of the negative electrode foil 22A made of copper, which has an X-ray shielding effect, it can be detected based on the change in contrast due to the X-ray shielding effect of the negative electrode foil 22A.
- boundary B2 is the end portion of the positive electrode active material covering portion 21B, it can be detected based on the change in contrast due to the X-ray shielding effect of the lithium-containing composite oxide or the like contained in the positive electrode active material covering portion 21B. can be done.
- Boundary B3 and boundary B4 can be detected based on changes in the contrast of the X-ray image due to irradiation with X-rays (locations denoted by reference sign BB in FIG. 7).
- boundary B3 is the end of the positive electrode active material covering portion 21B, it can be detected based on the change in contrast due to the X-ray shielding effect of the lithium-containing composite oxide or the like contained in the positive electrode active material covering portion 21B.
- boundary B4 is also the edge of the insulating layer 22D that has an X-ray shielding effect, it can be detected based on a change in contrast due to the X-ray shielding effect of the insulating layer 22D. Boundaries B1 to B4 can be detected based on these contrast changes.
- graphite which is the main component of the negative electrode active material coating portion 22B, has a higher X-ray shielding effect than the negative electrode foil 22A when the negative electrode foil 22A, whose main component is copper (Cu), is irradiated with X-rays having an intensity that penetrates the negative electrode foil 22A. is small, the boundary described above does not appear as a change in contrast in the X-ray image.
- the positive electrode active material covering portion 21B faces the negative electrode active material covering portion 22B
- the distance D10 (see FIGS. 4 and 7) between the end of the positive electrode active material coating portion 21B and the end of the negative electrode active material coating portion 22B is set large enough to prevent winding misalignment.
- the configuration of the lithium-ion battery was designed to minimize the occurrence of In such a configuration, there is a constraint that the length of the positive electrode active material covering portion 21B in the width direction is reduced, so there is a problem that the battery capacity cannot be increased.
- the positional relationship of each component is clarified, and the boundaries B1 to B4 can be detected, so it is possible to inspect winding misalignment.
- the quality of the lithium ion battery 1 can be ensured, and the safety can also be improved.
- it is no longer necessary to set the length of the positive electrode active material coating portion 21B in the width direction with a margin. can be increased. Thereby, the battery capacity of the lithium ion battery 1 can be increased.
- the main component of the negative electrode foil 22A is copper. Therefore, the insulating layer 22D is made of a metal (single element) or a metal compound having a sufficiently larger atomic weight (higher X-ray shielding effect) than copper.
- the containing layer is formed so as to be in contact with the end portion (coating end) of the negative electrode active material coating portion 22B. As a result, the edge of the negative electrode active material covering portion 22B can be detected from the change in contrast due to the shielding of X-rays.
- the atomic weight of copper is 63.55
- particles of yttrium oxide (Y 2 O 3 ), which is an oxide of yttrium (Y) having an atomic weight of 88.91 are polyfluorinated.
- the insulating layer 22D is formed by mixing with a coating material containing vinylidene and NMP, applying the coating material so as to be in contact with the end portion of the negative electrode active material coating portion 22B, and drying the coating material. As a result, the edge of the negative electrode active material covering portion 22B can be detected from the contrast of the X-ray transmission image.
- barium sulfate (BaSO 4 ) containing barium (Ba) having an atomic weight of 137.3 can be used instead of yttrium oxide.
- a simple substance of tungsten (W) having an atomic weight of 183.8 can be applied instead of yttrium oxide.
- strontium carbonate (SrCO 3 ) containing strontium (Sr) with an atomic weight of 87.62 can be applied instead of yttrium oxide.
- the electrode winding may peel off from the negative electrode active material covering portion 22B on the winding start side of the body 20 (longitudinal end side of the positive electrode or the negative electrode at the innermost circumference of the electrode wound body 20). This peeling is considered to be caused by the stress generated when pressing against the end surface 42 .
- the peeled negative electrode active material may enter the inside of the electrode winding body 20, thereby causing an internal short circuit.
- the second negative electrode active material non-coated portion 221B and the third negative electrode active material non-coated portion 221C are provided, it is possible to prevent the negative electrode active material from peeling off, thereby preventing the occurrence of an internal short circuit. Such an effect can also be obtained by providing only one of the second negative electrode active material uncovered portion 221B and the third negative electrode active material uncovered portion 221C, but it is more preferable to provide both.
- the negative electrode 22 can have a region of the negative electrode active material uncoated portion 22C on the principal surface of the side not facing the positive electrode active material coated portion 21B. This is because even if the negative electrode active material coating portion 22B is provided on the main surface that does not face the positive electrode active material coating portion 21B, it is considered that the contribution to charging and discharging is low. It is preferable that the area of the negative electrode active material non-coated portion 22C is 3/4 or more and 5/4 or less of the electrode wound body 20 . At this time, since the negative electrode active material coating portion 22B that contributes little to charging and discharging is not provided, the initial capacity can be increased with respect to the same volume of the electrode wound body 20 .
- the electrode winding body 20 is wound so that the positive electrode active material uncoated portion 21C and the negative electrode active material uncoated portion 22C face opposite directions.
- the material uncoated portions 21C gather, and the negative electrode active material uncoated portions 22C gather on the end surface 42 of the electrode winding body 20 .
- the positive electrode active material uncoated portion 21C and the first negative electrode active material uncoated portion 221A are bent to form flat end surfaces 41 and 42 .
- the bending direction is the direction from the outer edges 27 and 28 of the end faces 41 and 42 to the through hole 26 , and in the wound state, adjacent active material non-coated portions are overlapped and bent.
- the end surface 41 is a flat surface, the contact between the positive electrode active material uncoated portion 21C and the positive electrode current collector plate 24 can be improved, and the first negative electrode active material uncoated portion 221A and the negative electrode current collector can be improved. Good contact with the plate 25 can be achieved. In addition, since the end surfaces 41 and 42 are curved to form flat surfaces, the resistance of the lithium ion battery 1 can be reduced.
- the end surfaces 41 and 42 can be made flatter.
- Either one of the positive electrode active material uncoated portion 21C and the first negative electrode active material uncoated portion 221A may be bent, but both are preferably bent.
- the present invention will be specifically described below using the lithium ion battery 1 produced as described above and using examples and comparative examples in which the discharge capacity of the lithium ion battery 1 was evaluated. It should be noted that the present invention is not limited to the examples described below.
- the battery size is 21700 (diameter: 21 mm, height: 70 mm), the length in the longitudinal direction of the positive electrode active material coating portion 21B is 1320 mm, and the length in the longitudinal direction of the negative electrode active material coating portion 22B is The length was 1400 mm, the length in the width direction of the negative electrode active material coating portion 22B was 63 mm, and the length in the width direction of the separator 23 was 64 mm.
- the separator 23 was stacked so as to cover the entire range of the positive electrode active material covering portion 21B and the negative electrode active material covering portion 22B. Also, the number of the grooves 43 was set to 8, and they were arranged so as to have substantially equal angular intervals.
- 3 is a diagram corresponding to Example 1
- FIGS. 8 and 9 are diagrams corresponding to Comparative Example 1, respectively.
- Example 1 A lithium ion battery 1 was produced by the steps described above. At this time, as shown in FIG. 3, a negative electrode active material coated portion 22B and a negative electrode active material uncoated portion 22C are provided on both sides of the negative electrode foil 22A, and the negative electrode foil 22A is cut at the location of the negative electrode active material uncoated portion 22C. Thus, a first negative electrode active material uncovered portion 221A, a second negative electrode active material uncovered portion 221B, and a third negative electrode active material uncovered portion 221C were provided. Also, an insulating layer 22D is provided between the negative electrode active material covered portion 22B and the first negative electrode active material non-covered portion 221A. The length of the insulating layer 22D in the width direction was set to 3 (mm). A coating containing PVDF, barium sulfate particles, and NMP was applied, and the coating was dried to form the insulating layer 22D.
- a negative electrode foil 22A is provided with a negative electrode active material coated portion 22B and a negative electrode active material uncoated portion 22C on both sides, and the negative electrode foil 22A is cut at the negative electrode active material uncoated portion 22C.
- a first negative electrode active material uncovered portion 221A, a second negative electrode active material uncovered portion 221B, and a third negative electrode active material uncovered portion 221C were provided.
- an insulating layer 22E was provided between the negative electrode active material covered portion 22B and the first negative electrode active material non-covered portion 221A. The length of the insulating layer 22E in the width direction was set to 3 (mm).
- the insulating layer 22E was formed by using a paint containing no metal or metal oxide having an X-ray shielding effect. Lithium ion battery 1 was produced in the same manner as in Example 1 except for the above.
- the discharge capacity was measured as follows. Constant voltage/constant current charging was performed at 2000 mA for 3.5 hours in an atmosphere of 23° C. ⁇ 2° C. with a final voltage of 4.20 V. Thereafter, discharge was performed in the same atmosphere at 0.2 ItA (800 mA) with a final voltage of 2.0 V, and the capacity value was defined as the discharge capacity. Table 1 shows the results.
- Example 1 it was possible to inspect winding misalignment, so the distance D10 between the end of the positive electrode active material covering portion 21B and the end of the negative electrode active material covering portion 22B could be reduced.
- Comparative Example 1 since the insulating layer 22E does not contain a metal or the like having an X-ray shielding effect, as schematically indicated by reference numeral CC in FIG. Boundary B4 could not be detected. For this reason, it was not possible to inspect winding misalignment, and it was necessary to increase the distance D10 between the end of the positive electrode active material coating portion 21B and the end of the negative electrode active material coating portion 22B with a margin.
- Example 1 the length in the width direction of the positive electrode active material coating portion 21B was able to be made 2 mm larger than in Comparative Example 1. Since the length in the width direction of the positive electrode active material coating portion 21B was able to be increased, the discharge capacity of Example 1 was 4304 mAh, which was about 3% higher than the discharge capacity of Comparative Example 1 (4166 mAh). rice field. From the above, it can be said that the configuration corresponding to Example 1 is a preferable configuration of the lithium ion battery 1 .
- the present invention can also be applied to a tableless structure battery in which the positive electrode active material uncoated portion 21C and the first negative electrode active material uncoated portion 221A are not bent.
- the present invention can also be applied to a lithium ion battery without these.
- the number of grooves 43 was eight, but other numbers may be used.
- the battery size is 21700 (diameter 21 mm, height 70 mm), it may be 18650 (diameter 18 mm, height 65 mm) or other sizes.
- the fan-shaped portions 31 and 33 may have shapes other than the fan-shaped shape.
- the present invention can be applied to batteries other than lithium ion batteries and batteries other than cylindrical batteries (for example, laminate type batteries, square batteries, coin type batteries, button type batteries). is also possible.
- the shape of the "end surface of the wound electrode" may be not only cylindrical but also elliptical or flat.
- FIG. 10 is a block diagram showing a circuit configuration example when the secondary battery according to the embodiment or example of the present invention is applied to the battery pack 300.
- the battery pack 300 includes an assembled battery 301 , a switch section 304 including a charge control switch 302 a and a discharge control switch 303 a , a current detection resistor 307 , a temperature detection element 308 and a control section 310 .
- the control unit 310 can control each device, control charging/discharging when abnormal heat is generated, and calculate and correct the remaining capacity of the battery pack 300 .
- a positive terminal 321 and a negative terminal 322 of the battery pack 300 are connected to a charger or an electronic device, and charging and discharging are performed.
- the assembled battery 301 is formed by connecting a plurality of secondary batteries 301a in series and/or in parallel.
- FIG. 10 shows an example in which six secondary batteries 301a are connected in two parallel three series (2P3S).
- the secondary battery of the present invention can be applied to the secondary battery 301a.
- the temperature detection unit 318 is connected to a temperature detection element 308 (eg, a thermistor), measures the temperature of the assembled battery 301 or the battery pack 300, and supplies the measured temperature to the control unit 310.
- the voltage detection unit 311 measures the voltage of the assembled battery 301 and the secondary batteries 301 a that constitute it, A/D-converts the measured voltage, and supplies it to the control unit 310 .
- a current measurement unit 313 measures current using a current detection resistor 307 and supplies the measured current to the control unit 310 .
- the switch control section 314 controls the charge control switch 302a and the discharge control switch 303a of the switch section 304 based on the voltage and current input from the voltage detection section 311 and the current measurement section 313.
- the switch control unit 314 controls the switch unit 304 when the secondary battery 301a reaches the overcharge detection voltage (for example, 4.20V ⁇ 0.05V) or higher or the overdischarge detection voltage (2.4V ⁇ 0.1V) or lower. Overcharge or overdischarge is prevented by sending an OFF control signal to .
- the charge control switch 302a or the discharge control switch 303a After the charge control switch 302a or the discharge control switch 303a is turned off, charging or discharging is possible only through the diode 302b or the diode 303b.
- Semiconductor switches such as MOSFETs can be used for these charge/discharge switches. Note that although the switch section 304 is provided on the + side in FIG. 10, it may be provided on the - side.
- the memory 317 consists of RAM and ROM, and stores and rewrites the values of the battery characteristics calculated by the control unit 310, the full charge capacity, the remaining capacity, and the like.
- the secondary battery according to the embodiment or example of the present invention described above can be mounted on devices such as electronic devices, electric transportation devices, and power storage devices, and used to supply electric power.
- Examples of electronic devices include notebook computers, smartphones, tablet terminals, PDAs (personal digital assistants), mobile phones, wearable terminals, digital still cameras, e-books, music players, game machines, hearing aids, electric tools, televisions, and lighting equipment. , toys, medical devices, and robots. In a broad sense, electronic devices also include electric transportation equipment, power storage devices, power tools, and electric unmanned aerial vehicles, which will be described later.
- Electric transportation equipment includes electric vehicles (including hybrid vehicles), electric motorcycles, electrically assisted bicycles, electric buses, electric carts, automated guided vehicles (AGV), and railway vehicles. It also includes electric passenger aircraft and electric unmanned aerial vehicles for transportation.
- the secondary battery according to the present invention can be used not only as a driving power source, but also as an auxiliary power source, an energy regeneration power source, and the like.
- power storage devices include power storage modules for commercial or domestic use, power storage power sources for buildings such as houses, buildings, and offices, or for power generation equipment.
- the electric driver 431 is provided with a motor 433 that transmits rotational power to a shaft 434 and a trigger switch 432 that is operated by a user.
- a battery pack 430 and a motor control unit 435 are accommodated in a lower housing of the handle of the electric driver 431 .
- the battery pack 430 is built into the electric driver 431 or is detachable therefrom.
- the secondary battery of the present invention can be applied to the batteries forming battery pack 430 .
- Each of the battery pack 430 and the motor control unit 435 may be provided with a microcomputer (not shown) so that charge/discharge information of the battery pack 430 can be communicated with each other.
- the motor control unit 435 can control the operation of the motor 433 and cut off the power supply to the motor 433 in the event of an abnormality such as overdischarge.
- FIG. 12 schematically shows a configuration example of a hybrid vehicle (HV) employing a series hybrid system.
- a series hybrid system is a vehicle that runs with a power driving force conversion device using power generated by a generator driven by an engine or power temporarily stored in a battery.
- This hybrid vehicle 600 includes an engine 601, a generator 602, a power driving force conversion device (DC motor or AC motor, hereinafter simply referred to as "motor 603"), driving wheels 604a, driving wheels 604b, wheels 605a, wheels 605b, A battery 608, a vehicle control device 609, various sensors 610, and a charging port 611 are mounted.
- the battery 608 the secondary battery of the present invention or a power storage module equipped with a plurality of secondary batteries of the present invention can be applied.
- the electric power of the battery 608 operates the motor 603, and the rotational force of the motor 603 is transmitted to the driving wheels 604a and 604b.
- the rotational power produced by engine 601 allows power generated by generator 602 to be stored in battery 608 .
- Various sensors 610 control the engine speed via the vehicle control device 609 and control the opening of a throttle valve (not shown).
- HV plug-in hybrid vehicles
- the secondary battery according to the present invention can be applied to a miniaturized primary battery and use it as a power supply for the tire pressure monitoring system (TPMS) built into the wheels 604 and 605.
- TPMS tire pressure monitoring system
- the present invention can also be applied to a parallel system that uses both an engine and a motor, or a hybrid vehicle that combines a series system and a parallel system. Furthermore, the present invention can also be applied to an electric vehicle (EV or BEV) that runs only with a drive motor that does not use an engine, or a fuel cell vehicle (FCV).
- EV or BEV electric vehicle
- FCV fuel cell vehicle
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Abstract
Description
セパレータを介して帯状の正極と帯状の負極とが積層された電極巻回体と、正極集電板及び負極集電板とが、電池缶に収容された二次電池であって、
正極は、帯状の正極箔上に、正極活物質層が被覆された正極活物質被覆部と、正極活物質非被覆部とを有し、
負極は、帯状の負極箔上に、負極活物質層が被覆された負極活物質被覆部と、少なくとも負極箔の長手方向に延在する負極活物質非被覆部と、負極活物質被覆部と負極活物質非被覆部との間に設けられる絶縁層と、を有し、
正極活物質非被覆部は、電極巻回体の端部の一方において、正極集電板と接合され、
負極活物質非被覆部は、電極巻回体の端部の他方において、負極集電板と接合されており、
絶縁層は、X線遮蔽効果が所定より高い金属又は金属化合物を含有する
二次電池である。
<一実施形態>
<変形例>
<応用例>
以下に説明する実施形態等は本発明の好適な具体例であり、本発明の内容がこれらの実施形態等に限定されるものではない。なお、説明の理解を容易とするために、各図における一部の構成を拡大したり、若しくは縮小したり、一部の図示を簡略化する場合もある。
[リチウムイオン電池の全体構成例]
本発明の一実施形態では、二次電池として、円筒形状のリチウムイオン電池を例にして説明する。図1から図5を参照しつつ、本実施形態に係るリチウムイオン電池(リチウムイオン電池1)の全体構成に関して説明する。図1は、リチウムイオン電池1の概略断面図である。リチウムイオン電池1は、例えば、図1に示すように、電池缶11の内部に電極巻回体20が収納されている円筒型のリチウムイオン電池1である。
電池缶11は、主に、電極巻回体20を収納する部材である。この電池缶11は、例えば、一端面が開放されると共に他端面が閉塞された円筒状の容器である。即ち、電池缶11は、開放された一端面(開放端面11N)を有している。この電池缶11は、例えば、鉄、アルミニウム及びそれらの合金などの金属材料のうちのいずれか1種類又は2種類以上を含んでいる。電池缶11の表面に、例えば、ニッケルなどの金属材料のうちのいずれか1種類又は2種類以上が鍍金されていてもよい。
絶縁板12,13は、電極巻回体20の中心軸(電極巻回体20の端面の略中心を通り図1のZ軸と平行な方向)に対して略垂直な面を有する円板状の板である。また、絶縁板12,13は、例えば、互いに電極巻回体20を挟むように配置されている。
電池缶11の開放端面11Nには、電池蓋14及び安全弁機構30がガスケット15を介してかしめられており、かしめ構造11R(クリンプ構造)が形成されている。これにより、電池缶11の内部に電極巻回体20などが収納された状態において、その電池缶11は密閉されている。
電池蓋14は、主に、電池缶11の内部に電極巻回体20などが収納された状態において、その電池缶11の開放端面11Nを閉塞する部材である。この電池蓋14は、例えば、電池缶11の形成材料と同様の材料を含んでいる。電池蓋14のうちの中央領域は、例えば、+Z方向に突出している。これにより、電池蓋14のうちの中央領域以外の領域(周辺領域)は、例えば、安全弁機構30に接触している。
ガスケット15は、主に、電池缶11(折り曲げ部11P)と電池蓋14との間に介在することにより、その折り曲げ部11Pと電池蓋14との間の隙間を封止する部材である。ガスケット15の表面に、例えば、アスファルトなどが塗布されていてもよい。
安全弁機構30は、主に、電池缶11の内部の圧力(内圧)が上昇した際に、必要に応じて電池缶11の密閉状態を解除することにより、その内圧を開放する。電池缶11の内圧が上昇する原因は、例えば、充放電時において電解液の分解反応に起因して発生するガスなどである。
円筒形状のリチウムイオン電池1では、帯状の正極21と帯状の負極22とがセパレータ23を挟んで積層され、且つ、渦巻き状に巻回されて電解液に含浸された状態で、電池缶11に収まっている。正極21は正極箔21Aの片面又は両面に正極活物質層21Bを形成したものであり、正極箔21Aの材料は例えば、アルミニウムやアルミニウム合金でできた金属箔である。負極22は負極箔22Aの片面又は両面に負極活物質層22Bを形成したものであり、負極箔22Aの材料は例えば、ニッケル、ニッケル合金、銅や銅合金でできた金属箔である。セパレータ23は多孔質で絶縁性のあるフィルムであり、正極21と負極22とを電気的に絶縁しながら、イオンや電解液等の物質の移動を可能にしている。
通常のリチウムイオン電池では例えば、正極と負極との一か所ずつに電流取出し用のリードが溶接されているが、これでは電池の内部抵抗が大きく、放電時にリチウムイオン電池が発熱し高温になるため、ハイレート放電には適さない。そこで、本実施形態のリチウムイオン電池1では、電極巻回体20の一方の端面である端面41に正極集電板24を配置し、電極巻回体20の他方の端面である端面42に負極集電板25を配置する。そして、正極集電板24と端面41に存在する正極活物質非被覆部21Cとを多点で溶接し、また、負極集電板25と端面42に存在する第1の負極活物質非被覆部221Aとを多点で溶接することで、リチウムイオン電池1の内部抵抗を低く抑え、ハイレート放電を可能としている。
正極活物質層21Bは、リチウムを吸蔵及び放出することが可能である正極材料(正極活物質)を少なくとも含み、さらに、正極結着剤及び正極導電剤などを含んでいてもよい。正極材料は、リチウム含有複合酸化物又はリチウム含有リン酸化合物が好ましい。リチウム含有複合酸化物は、例えば、層状岩塩型又はスピネル型の結晶構造を有している。リチウム含有リン酸化合物は、例えば、オリビン型の結晶構造を有している。
負極22を構成する負極箔22Aの表面は、負極活物質層22Bとの密着性向上のために粗面化されていることが好ましい。負極活物質層22Bは、リチウムを吸蔵及び放出することが可能である負極材料(負極活物質)を少なくとも含み、さらに、負極結着剤及び負極導電剤などを含んでいてもよい。
セパレータ23は、樹脂を含む多孔質膜であり、2種類以上の多孔質膜の積層膜でもよい。樹脂は、ポリプロピレン及びポリエチレンなどである。セパレータ23は、多孔質膜を基材層として、その片面又は両面に樹脂層を含んでいてもよい。正極21及び負極22のそれぞれに対するセパレータ23の密着性が向上するため、電極巻回体20の歪みが抑制されるからである。
電解液は、溶媒及び電解質塩を含み、必要に応じてさらに添加剤などを含んでいてもよい。溶媒は、有機溶媒などの非水溶媒、又は水である。非水溶媒を含む電解液を非水電解液という。非水溶媒は、環状炭酸エステル、鎖状炭酸エステル、ラクトン、鎖状カルボン酸エステル又はニトリル(モノニトリル)などである。
次に、上述した絶縁層22Dの詳細について説明する。絶縁層22Dは、例えば、PVDF等の樹脂を含む。絶縁層22Dは、更に無機粒子または有機粒子を含んでも良い。無機粒子の例としては例えば、酸化アルミニウム、窒化アルミニウム、水酸化アルミニウム、水酸化マグネシウム、ベーマイト、タルク、シリカ、雲母などの何れか1種、または2種以上を含むものが挙げられる。
次に、図6Aから図6Fを参照して、一実施形態に係るリチウムイオン電池1の作製方法について説明する。まず、正極活物質を、帯状の正極箔21Aの表面に塗着させ、これを正極活物質被覆部21Bとし、負極活物質を、帯状の負極箔22Aの表面に塗着させ、これを負極活物質被覆部22Bとした。このとき、正極箔21Aの幅方向の一端側に正極活物質が塗着されていない正極活物質非被覆部21Cを設け、負極箔22Aに、負極活物質が塗着されていない負極活物質非被覆部22C(第1の負極活物質非被覆部221A、第2の負極活物質非被覆部221B及び第3の負極活物質非被覆部221C)を設けた。また、負極活物質被覆部22Bを設ける際に絶縁層22Dを設けた。次に、正極21と負極22とに対して乾燥等の工程を行った。そして、正極活物質非被覆部21Cと負極活物質非被覆部22Cとが逆方向となるようにセパレータ23を介して重ね、中心軸に貫通孔26ができるように渦巻き状に巻回して、図6Aのような電極巻回体20を作製した。
(絶縁層の作用及び効果)
図7を参照し絶縁層22Dの作用、及び、絶縁層22Dを設けることにより得られる効果について説明する。図7は、図4における切断線XA-XAで電極巻回体20を切断した場合の断面を示す図である。説明の便宜を考慮して、図7では、正極21、負極22、及び、セパレータ23を1層ずつ示している。また、図7では、リチウムイオン電池1の正極側にX線を照射した場合に得られるX線画像のコントラストを、断面図に対して左上側に模式的に示し、また、リチウムイオン電池1の負極側にX線を照射した場合に得られるX線画像のコントラストを、断面図に対して左下側に模式的に示している。
リチウムイオン電池1の作製時において、薄い平板(例えば厚さ0.5mm)などの端を端面41,42に対して垂直に押し付ける際に(図6Bに示す工程を行う際に)、電極巻回体20の巻回開始側(電極巻回体20の最内周にある正極又は負極の長手方向の端側)において、負極活物質被覆部22Bから負極活物質が剥離することがある。この剥離は端面42に対して押し付ける際に発生するストレスが原因と考えられる。剥離した負極活物質が電極巻回体20内部に侵入し、これにより内部ショートが発生する虞がある。本実施形態では、第2の負極活物質非被覆部221B及び第3の負極活物質非被覆部221Cを設けているので負極活物質の剥離を防ぐことができ、内部ショートの発生を防止できる。係る効果は、第2の負極活物質非被覆部221B及び第3の負極活物質非被覆部221Cの一方のみを設ける構成によっても得られるが、両方設けることがより好ましい。
図3は実施例1に、図8及び図9は比較例1にそれぞれ対応する図である。
リチウムイオン電池1を上述した工程により作製した。この際、図3に示すように、負極箔22Aの両面に、負極活物質被覆部22B及び負極活物質非被覆部22Cを設け、負極活物質非被覆部22Cの箇所で負極箔22Aをカットすることで、第1の負極活物質非被覆部221A、第2の負極活物質非被覆部221B、及び、第3の負極活物質非被覆部221Cを設けた。また、負極活物質被覆部22Bと第1の負極活物質非被覆部221Aとの間に絶縁層22Dを設けた。絶縁層22Dの幅方向の長さは3(mm)とした。PVDFと硫酸バリウム粒子とNMPを含む塗料を塗布し、塗膜を乾燥することによって絶縁層22Dを形成した。
図8Aに示すように、負極箔22Aの両面に、負極活物質被覆部22B及び負極活物質非被覆部22Cを設け、負極活物質非被覆部22Cの箇所で負極箔22Aをカットすることで、第1の負極活物質非被覆部221A、第2の負極活物質非被覆部221B、及び、第3の負極活物質非被覆部221Cを設けた。また、負極活物質被覆部22Bと第1の負極活物質非被覆部221Aとの間に絶縁層22Eを設けた。絶縁層22Eの幅方向の長さは3(mm)とした。絶縁層22Eは、X線遮蔽効果を有する金属や金属酸化物を含有しない塗料を用いることで形成した。その他は、実施例1と同様にリチウムイオン電池1を作製した。
放電容量は、以下のように測定した。23℃±2℃の雰囲気下で4.20Vを終止電圧とし、2000mAでの定電圧・定電流充電を3.5時間行った。その後、同じ雰囲気で0.2ItA(800mA)、2.0Vを終止電圧とした放電を行った場合の容量値を放電容量とした。結果を表1に示す。
以上から、実施例1に対応する構成がリチウムイオン電池1の好ましい構成と言える。
以上、本発明の一実施形態について具体的に説明したが、本発明の内容は上述した一実施形態に限定されるものではなく、本発明の技術的思想に基づく各種の変形が可能である。
実施例及び比較例では、溝43の数を8としていたが、これ以外の数であってもよい。電池サイズを21700(直径21mm,高さ70mm)としていたが、18650(直径18mm,高さ65mm)やこれら以外のサイズであってもよい。
扇状部31,33の形状は、扇形の形状以外の形状であってもよい。
(1)電池パック
図10は、本発明の実施形態又は実施例に係る二次電池を電池パック300に適用した場合の回路構成例を示すブロック図である。電池パック300は、組電池301、充電制御スイッチ302aと、放電制御スイッチ303a、を備えるスイッチ部304、電流検出抵抗307、温度検出素子308、制御部310を備えている。制御部310は各デバイスの制御を行い、さらに異常発熱時に充放電制御を行ったり、電池パック300の残容量の算出や補正を行ったりすることが可能である。電池パック300の正極端子321及び負極端子322は、充電器や電子機器に接続され、充放電が行われる。
上述した本発明の実施形態又は実施例に係る二次電池は、電子機器や電動輸送機器、蓄電装置などの機器に搭載され、電力を供給するために使用することができる。
図11を参照して、本発明が適用可能な電動工具として電動ドライバの例について概略的に説明する。電動ドライバ431には、シャフト434に回転動力を伝達するモータ433と、ユーザが操作するトリガースイッチ432が設けられている。電動ドライバ431の把手の下部筐体内に、電池パック430及びモータ制御部435が収納されている。電池パック430は、電動ドライバ431に対して内蔵されているか、又は着脱自在とされている。電池パック430を構成する電池に対して、本発明の二次電池を適用可能である。
本発明を電動車両用の蓄電システムに適用した例として、図12に、シリーズハイブリッドシステムを採用したハイブリッド車両(HV)の構成例を概略的に示す。シリーズハイブリッドシステムはエンジンを動力とする発電機で発電された電力、あるいはそれをバッテリに一旦貯めておいた電力を用いて、電力駆動力変換装置で走行する車である。
Claims (9)
- セパレータを介して帯状の正極と帯状の負極とが積層された電極巻回体と、正極集電板及び負極集電板とが、電池缶に収容された二次電池であって、
前記正極は、帯状の正極箔上に、正極活物質層が被覆された正極活物質被覆部と、正極活物質非被覆部とを有し、
前記負極は、帯状の負極箔上に、負極活物質層が被覆された負極活物質被覆部と、少なくとも前記負極箔の長手方向に延在する負極活物質非被覆部と、前記負極活物質被覆部と前記負極活物質非被覆部との間に設けられる絶縁層と、を有し、
前記正極活物質非被覆部は、前記電極巻回体の端部の一方において、前記正極集電板と接合され、
前記負極活物質非被覆部は、前記電極巻回体の端部の他方において、前記負極集電板と接合されており、
前記絶縁層は、X線遮蔽効果が所定より高い金属又は金属化合物を含有する
二次電池。 - 前記絶縁層は、前記負極箔を構成する金属よりもX線遮蔽効果が高い金属、又は、前記負極箔を構成する金属よりもX線遮蔽効果が高い金属を含む金属化合物を含有する
請求項1に記載の二次電池。 - 前記金属は、タングステン(W)、イリジウム(Ir)、白金(Pt)、及び、金(Au)からなる群より選ばれる1つ以上であり、
前記金属化合物は、金属酸化物、金属硫酸塩化合物、及び、金属炭酸塩化合物からなる群より選ばれる1つ以上である
請求項2に記載の二次電池。 - 前記金属酸化物は、酸化イットリウム、酸化ハフニウム、五酸化タンタル、及び、酸化タングステンからなる群より選ばれる1つ以上であり、
前記金属硫酸塩化合物は、硫酸バリウム、及び、硫酸ストロンチウムからなる群より選ばれる1つ以上であり、
前記金属炭酸塩化合物は、炭酸ストロンチウムである
請求項3に記載の二次電池。 - 前記負極箔を構成する金属は銅である
請求項2から4までの何れかに記載の二次電池。 - 前記電極巻回体は、前記正極活物質非被覆部及び前記負極活物質非被覆部の何れか一方又は両方が、前記巻回された構造の中心軸に向かって曲折し、重なり合うことによって形成された平坦面と、前記平坦面に形成された溝とを有する
請求項1から5までの何れかに記載の二次電池。 - 前記負極は、更に、長手方向の巻回開始側及び巻回終止側のそれぞれの端部に、負極活物質非被覆部を有する
請求項1から6までの何れかに記載の二次電池。 - 請求項1から7までの何れかに記載の二次電池を有する電子機器。
- 請求項1から7までの何れかに記載の二次電池を有する電動工具。
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JP2000090958A (ja) * | 1998-09-14 | 2000-03-31 | Fuji Photo Film Co Ltd | 電池の検査装置及び検査方法 |
JP2007095656A (ja) * | 2005-08-30 | 2007-04-12 | Sanyo Electric Co Ltd | 非水系二次電池 |
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JP2000090958A (ja) * | 1998-09-14 | 2000-03-31 | Fuji Photo Film Co Ltd | 電池の検査装置及び検査方法 |
JP2007095656A (ja) * | 2005-08-30 | 2007-04-12 | Sanyo Electric Co Ltd | 非水系二次電池 |
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