WO2016079821A1 - Lithium ion battery and production method therefor - Google Patents

Lithium ion battery and production method therefor Download PDF

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Publication number
WO2016079821A1
WO2016079821A1 PCT/JP2014/080595 JP2014080595W WO2016079821A1 WO 2016079821 A1 WO2016079821 A1 WO 2016079821A1 JP 2014080595 W JP2014080595 W JP 2014080595W WO 2016079821 A1 WO2016079821 A1 WO 2016079821A1
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Prior art keywords
mixture layer
porosity
ion battery
electrode mixture
lithium ion
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PCT/JP2014/080595
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French (fr)
Japanese (ja)
Inventor
新平 尼崎
利光 野口
祐介 加賀
和明 直江
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株式会社日立製作所
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Priority to PCT/JP2014/080595 priority Critical patent/WO2016079821A1/en
Publication of WO2016079821A1 publication Critical patent/WO2016079821A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H01M10/0587—Construction or manufacture of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
    • 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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • 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 a lithium ion battery and a manufacturing method thereof.
  • Patent Document 1 JP 2013-008523 A
  • Patent Document 2 JP 2011-175739 A
  • Patent Document 1 states that “a mixture layer containing an active material is formed on the surface of a current collector, and this mixture layer has a different porosity depending on the position along the surface of the current collector.
  • the battery electrode having "" is described.
  • Patent Document 2 states that “the electrode film formed on the electrode surface is a mixture layer having a small gap and a small active material density, but a high active material density; "A lithium ion battery having an electrode film structure combined with a mixture layer having a large void size that easily penetrates” is described.
  • Lithium ion batteries are required to achieve both improved productivity and improved battery characteristics.
  • Patent Document 1 describes a lithium ion battery electrode that secures a migration path of lithium ions in an electrode mixture layer and improves input / output characteristics, and a manufacturing method thereof. However, no mention is made regarding the permeation time of the electrolytic solution, and the structure of the lithium ion battery electrode of Patent Document 1 is not optimal for shortening the permeation time of the electrolytic solution.
  • Patent Document 2 discloses a lithium ion battery that uses an active material from which fine powder has been removed and uses an electrode mixture layer having a large void size as an electrolyte solution supply path, thereby reducing the electrolyte solution penetration time. Is described. However, since fine powder has the characteristics that the diffusion distance of lithium ions in the active material is short and the reaction area per active material weight is large, the active material containing fine powder is suitable for improving input / output characteristics. ing. Therefore, an active material from which fine powder has been removed is disadvantageous for improving input / output characteristics. Furthermore, in the method for producing an electrode film of Patent Document 2, the number of steps for removing fine powder increases and the number of steps for applying an electrode mixture increases to two, leading to an increase in the number of electrode production steps.
  • the present invention provides a lithium ion battery capable of achieving both improvement in productivity and improvement in battery characteristics by shortening the permeation time of the electrolytic solution and reducing the internal resistance during charging and discharging. A manufacturing method thereof is provided.
  • a lithium ion battery according to the present invention has a positive electrode, a separator, and a negative electrode that are stacked in an outer can having a can lid and a can bottom at positions facing each other.
  • An electrode winding body wound around is provided.
  • a positive electrode mixture layer having a high porosity and a positive electrode mixture layer having a low porosity are alternately formed in the winding direction on the surface of the current collector foil.
  • a negative electrode mixture layer having a high porosity and a negative electrode mixture layer having a low porosity are alternately formed in the winding direction.
  • the particle size distribution of the active material contained in each of the positive electrode mixture layer having a high porosity and the positive electrode mixture layer having a low porosity is the same, and the negative electrode mixture layer having a high porosity and the negative electrode mixture having a low porosity are used.
  • the particle size distribution of the active material contained in each of the layers is the same.
  • FIG. 2 is a cross-sectional view showing an internal structure of a cylindrical lithium ion battery according to Example 1.
  • FIG. (A), (b) and (c) are schematic views showing a metal member for drying used in the drying step after slurry application according to Example 1, a positive electrode mixture layer during drying, and a positive electrode mixture layer after drying, respectively. It is.
  • (A) And (b) is the schematic diagram of the 1st example and 2nd example of the electrode winding body by which the two electrode mixture layers by which the porosity from Example 1 differs mutually were formed alternately in the winding direction, respectively It is.
  • (A), (b), and (c) are a drying metal member, a positive electrode mixture layer being dried, and a positive electrode mixture layer after drying, respectively, used in the drying step after slurry application according to the modification of Example 1.
  • (A) And (b) is a principal part top view which shows the other example of two positive mix layers from which the porosity in Example 1 differs. It is a graph which shows the osmosis
  • (A), (b) and (c) are schematic diagrams showing a drying metal member, a positive electrode mixture layer being dried, and a positive electrode mixture layer after drying, respectively, used in the drying step after slurry application according to Example 2. It is. It is a schematic diagram of the 4th example of the electrode winding body which has the electrode in which the area
  • (A), (b), and (c) are the schematic diagrams which respectively show the shielding board used at the drying process after slurry application
  • the constituent elements are not necessarily indispensable unless otherwise specified and clearly considered essential in principle. Needless to say.
  • the positive electrode and the negative electrode are collectively referred to as “electrode”, and the positive electrode mixture and the negative electrode mixture are collectively referred to as “electrode mixture”.
  • the positive electrode material, the negative electrode material, and the insulating material before the drying process using the drying furnace are substances having fluidity including liquids such as a binder solution and an organic solvent.
  • the surface of the current collector foil refers to only the front surface, not the entire surface including the front surface and the back surface of the current collector foil.
  • FIG. 1 is a cross-sectional view showing the internal structure of a cylindrical lithium ion battery according to the first embodiment.
  • the lithium ion battery LIB has a cylindrical outer can CS having a bottom, and inside the outer can CS, an electrode container made up of a positive electrode PEL, separators SP1, SP2, and a negative electrode NEL.
  • a circular WRF is formed.
  • the electrode winding body WRF is laminated so as to sandwich the separator SP1 (or SP2) between the positive electrode PEL and the negative electrode NEL, and is wound around the axis CR at the center of the outer can CS. Has been.
  • the positive electrode current collection tab PTAB formed in the positive electrode PEL is arrange
  • the negative electrode current collecting tab NTAB formed on the negative electrode NEL is disposed on the lower side of the electrode winding body WRF and is electrically connected to the negative electrode lead plate NT provided on the lower part (bottom part) of the outer can CS. Has been.
  • the electrolyte is injected into the electrode winding body WRF formed inside the outer can CS.
  • the outer can CS is sealed with a battery lid CAP.
  • the outer can CS is made mainly of, for example, iron (Fe) or stainless steel.
  • the symbol PR indicates a positive electrode ring
  • the symbol NR indicates a negative electrode ring.
  • the positive electrode PEL is formed by applying a positive electrode mixture layer PEF made of a positive electrode active material, a binder (binder) and a conductive additive to the current collector foil PEP.
  • the positive electrode active material examples include, but are not limited to, lithium cobaltate, lithium nickelate, and lithium manganate.
  • the positive electrode active material is a material capable of inserting / extracting lithium ions, and may be any lithium-containing transition metal oxide in which a sufficient amount of lithium (Li) has been previously inserted. It may be a simple substance such as manganese (Mn), nickel (Ni), cobalt (Co) or iron (Fe), or a material mainly composed of two or more kinds of transition metals.
  • the crystal structure such as the spinel crystal structure or the layered crystal structure is not particularly limited as long as the above-described site and channel are ensured.
  • transition metals or lithium (Li) in the crystal are replaced with elements such as iron (Fe), cobalt (Co), nickel (Ni), chromium (Cr), aluminum (Al) or manganese (Mg).
  • the obtained material may be used as the positive electrode active material.
  • a material doped with an element such as iron (Fe), cobalt (Co), nickel (Ni), chromium (Cr), aluminum (Al) or manganese (Mg) in the crystal may be used as the positive electrode active material. Good.
  • binder for example, polyvinyl fluoride, polyvinylidene fluoride, polytetrafluoroethylene, or the like can be used.
  • current collector foil PEP for example, a metal foil or a net-like metal made of a conductive metal such as aluminum (Al) is used.
  • the negative electrode NEL is formed by applying a negative electrode mixture layer NEF made of a negative electrode active material, a binder (binder) and a conductive additive to the current collector foil NEP.
  • the negative electrode active material examples include a crystalline carbon material and an amorphous carbon material, but are not limited thereto.
  • the negative electrode active material may be any carbon material that can insert and desorb lithium ions, and carbon materials such as natural graphite, various artificial graphite agents, and coke can be used.
  • oxides such as silicon oxide, niobium oxide or titanium oxide, or silicon (Si), tin (Sn), germanium (Ge), lead (Pb) or aluminum (Al)
  • a material that forms an alloy with lithium (Li), which is typified, or a mixture thereof can be used.
  • various particle shapes such as a scale shape, a spherical shape, a fiber shape or a lump shape are applicable.
  • binder for example, polyvinylidene fluoride or polytetrafluoroethylene can be used.
  • the current collector foil NEP for example, a metal foil or a net-like metal made of a conductive metal such as copper (Cu) is used.
  • the separators SP1 and SP2 have a function as a spacer that allows lithium ions to pass through while insulating between the positive electrode and the negative electrode and preventing electrical contact.
  • high-strength and thin microporous membranes are used as the separators SP1 and SP2.
  • the separators SP1 and SP2 composed of the microporous membrane are composed of, for example, polyethylene (PE (polyethylene)) or polypropylene (PP (polypropylene)), or a combination of these materials.
  • a nonaqueous electrolytic solution is used as an electrolytic solution in which a charge / discharge reaction is performed between the positive electrode and the negative electrode.
  • the lithium ion battery LIB is a battery that performs charging / discharging by using insertion / extraction of lithium ions in an active material, and lithium ions move in an electrolytic solution.
  • Lithium is a strong reducing agent and reacts violently with water to generate hydrogen gas. Therefore, in the lithium ion battery LIB in which lithium ions move in the electrolytic solution, an aqueous solution cannot be used as the electrolytic solution as in the conventional battery. For this reason, in the lithium ion battery LIB, a non-aqueous electrolyte is used as the electrolyte.
  • LiPF 6, LiClO 4, LiAsF 6, LiBF 4, LiB (C 6 H 5) 4, such as CH 3 SO 3 Li or CF 3 SO 3 Li, or their Mixtures can be used.
  • organic solvent ethylene carbonate, dimethyl carbonate, ethyl methyl carbonate, propylene carbonate, or diethyl carbonate can be used.
  • examples of the organic solvent include 1,2-dimethoxyethane, 1,2-diethoxyethane, ⁇ -butyrolactone, tetrahydrofuran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, diethyl ether, sulfolane, methylsulfolane. Acetonitrile or propionitrile can be used. Furthermore, as the organic solvent, the above-mentioned mixed liquid of organic solvents can be used.
  • a method for injecting the electrolytic solution a method of injecting the electrolytic solution from the can bottom side and infiltrating the electrolytic solution from the can bottom side of the electrode winding body WRF toward the can lid side, or the electrolytic solution Is injected from the can lid side, and the electrolyte solution penetrates from the can lid side of the electrode winding body WRF toward the can bottom side.
  • the electrode winding body WRF has a path through which the electrolyte can easily penetrate in the direction of the can lid-can bottom (the direction from the can lid to the can bottom or the direction from the can bottom to the can lid). It is effective to provide it.
  • Example 1 as a path through which the electrolytic solution easily permeates, an electrode mixture layer having a high porosity in the direction of the can lid-can bottom of the electrode winding body WRF, for example 40 An electrode mixture layer having a porosity of about volume% was formed.
  • Example 1 a lithium ion battery electrode in which two or more electrode mixture layers having different porosities are formed in the winding direction is formed through a drying process described below. Further, each of the two or more electrode mixture layers having different porosity from one side of the current collector foil along the winding direction toward the other side of the current collector foil along the winding direction. It is formed.
  • Electrode and electrode winding body manufacturing method The manufacturing method of the electrode and electrode winding body according to the first embodiment will be described below.
  • Lithium manganese cobalt nickel composite oxide for the positive electrode active material graphite powder for the conductive additive, polyvinylidene fluoride (PVDF) for the binder, and aluminum foil for the current collector foil To do. These were mixed so that the weight percentages of the positive electrode active material, the conductive additive and the binder were 93.0, 3.5 and 3.5, respectively, and further N-methyl-2-pyrrolidone (NMP (N-methylpyrrolidone ); Hereinafter simply referred to as NMP) to produce a positive electrode slurry (slurry positive electrode material).
  • NMP N-methyl-2-pyrrolidone
  • the weight of NMP is adjusted so that the solid content ratio (weight of the solid content (positive electrode active material, conductive additive and binder) with respect to the slurry weight) is 66% by weight, and the slurry viscosity is 1 Pa ⁇ s. adjust.
  • FIGS. 2 (a), (b) and (c) Next, the drying process will be described with reference to FIGS. 2 (a), (b) and (c).
  • the manufacturing method of the positive electrode will be described, but the manufacturing method of the negative electrode is substantially the same.
  • 2 (a), 2 (b), and 2 (c) show a drying metal member, a positive electrode mixture layer during drying, and a positive electrode mixture layer after drying, respectively, used in the drying step after slurry application according to the first embodiment. It is a schematic diagram shown.
  • the drying metal member MD1 includes a plurality of metal lines MW arranged with a first pitch P1 in the first direction, and a metal plate MP connected to one end of the plurality of metal lines MW. That is, the metal plate MP and the plurality of metal wires MW are integrally formed, and the plurality of metal wires MW are fixed by the metal plate MP.
  • the line width of the plurality of metal lines MW is, for example, 0.1 to 1.0 mm
  • the first pitch P1 in the first direction of the plurality of metal lines MW is, for example, 10 mm.
  • the drying metal member MD1 (the metal plate MP and the plurality of metal wires MW) is made of, for example, stainless steel, iron (Fe), gold (Au), silver (Ag), iron (Fe) alloy, nickel (Ni) alloy, or the like.
  • the cross section along the first direction of the metal line MW is substantially circular, but is not limited thereto, and may be, for example, a substantially square shape.
  • the current collector foil PEP having the positive electrode mixture layer PEF applied on the surface thereof is mounted on the metal member MD1 for drying.
  • the current collector foil PEP is mounted such that one of the two sides along the conveying direction of the current collector foil PEP is placed on the metal plate MP of the drying metal member MD1. That is, the first direction coincides with the conveying direction of the current collector foil PEP.
  • the current collector foil PEP mounted on the drying metal member MD1 is conveyed into, for example, a 120 ° C. hot-air drying furnace, and applied to the surface of the current collector foil PEP.
  • the layer PEF is dried.
  • the conveying speed of the current collector foil PEP is, for example, 5 to 100 m / min. At the time of mass production, productivity can be maintained by conveying the drying metal member MD1 together with the current collector foil PEP in the hot air drying furnace at a constant speed.
  • the porosity of the positive electrode mixture layer PEFH that is not located on the metal plate MP and the plurality of metal wires MW of the metal member MD1 for drying It becomes higher than the porosity of the positive electrode mixture layer PEFL located on the metal plate MP and the plurality of metal wires MW of the drying metal member MD1.
  • a positive electrode mixture layer PEFL with a width of 5 mm and a low porosity and a positive electrode mixture layer PEFH with a width of 5 mm and a high porosity are alternately formed in the conveying direction of the current collector foil PEP.
  • a positive electrode composite having a low porosity is formed on a portion having a predetermined width from one side of the current collector foil PEP along the conveying direction of the current collector foil PEP (a portion where the current collector foil PEP and the metal plate MP overlap).
  • the agent layer PEFL is formed.
  • a positive electrode is manufactured by press-compressing the dried positive electrode mixture layer PEF.
  • the negative electrode can be produced in the same manner.
  • 3 (a) and 3 (b) respectively show a first example of an electrode winding body having electrodes in which two electrode mixture layers having different porosities according to Example 1 are alternately formed in the winding direction. It is a schematic diagram of the 2nd example.
  • the first example of the electrode winding body WRF includes a positive electrode PEL wound around the axis CR, separators SP1 and SP2, and a negative electrode NEL.
  • the positive electrode PEL the positive electrode mixture layer PEFH having a high porosity and the positive electrode mixture layer PEFL having a low porosity are alternately formed in the winding direction.
  • the negative electrode NEL the negative electrode mixture layer having a high porosity. NEFH and a negative electrode mixture layer NEFL having a low porosity are alternately formed in the winding direction.
  • the positive electrode mixture layer PEFL having a low porosity formed along the conveying direction of the current collector foil PEP is wound so as to be positioned on the positive electrode current collector tab PTAB side.
  • the negative electrode mixture layer NEFL having a low porosity formed along the conveying direction of the current collector foil NEP is wound so as to be positioned on the positive electrode current collector tab PTAB side.
  • the first example of the electrode winding body WRF includes the positive electrode PEL on which the positive electrode mixture layer PEFH having a high porosity is formed from the can bottom side toward the can lid direction, and the can bottom side toward the can lid direction.
  • a negative electrode mixture layer NEFH having a high porosity is formed from the can bottom side toward the can lid direction.
  • the second example of the electrode winding body WRF is similar to the first example of the electrode winding body WRF, the positive electrode PEL wound around the axis CR, the separator SP1 and SP2 and negative electrode NEL are comprised.
  • the positive electrode PEL the positive electrode mixture layer PEFH having a high porosity and the positive electrode mixture layer PEFL having a low porosity are alternately formed in the winding direction.
  • the negative electrode NEL the negative electrode mixture layer having a high porosity.
  • NEFH and a negative electrode mixture layer NEFL having a low porosity are alternately formed in the winding direction.
  • the positive electrode mixture layer PEFL having a low porosity formed along the conveying direction of the current collector foil PEP is formed as the negative electrode collector.
  • the negative electrode mixture layer NEFL having a low porosity formed along the conveying direction of the current collector foil NEP is wound so as to be positioned on the negative electrode current collector tab NTAB side. ing. Therefore, the second example of the electrode winding body WRF includes the positive electrode PEL on which the positive electrode mixture layer PEFH having a high porosity is formed from the can lid side toward the can bottom direction, and the can lid side toward the can bottom direction.
  • the positive electrode mixture layer PEF is formed on the surface of the current collector foil PEP, and the negative electrode mixture layer NEF is formed on the surface of the current collector foil NEP, in the same manner as the coating step described above.
  • FIG. 4 (a), (b) and (c) Next, a drying process is demonstrated using FIG. 4 (a), (b) and (c).
  • the manufacturing method of the positive electrode will be described, but the manufacturing method of the negative electrode is substantially the same.
  • 4 (a), (b) and (c) respectively show the metal member for drying used in the drying step after slurry application according to the modified example of Example 1, the positive electrode mixture layer during drying, and the positive electrode mixture after drying. It is a schematic diagram which shows an agent layer.
  • a drying metal member MD2 shown in FIG. 4 (a) is prepared.
  • the drying metal member MD2 is composed of a plurality of metal lines MW arranged with a second pitch P2 in the first direction.
  • One end and the other end of the plurality of metal wires MW are connected by a support member, and the plurality of metal wires MW are fixed.
  • the line width of the plurality of metal lines MW is, for example, 0.1 to 1.0 mm
  • the second pitch P2 in the first direction of the plurality of metal lines MW is, for example, 10 mm.
  • the plurality of metal wires MW are made of, for example, stainless steel, iron (Fe), gold (Au), silver (Ag), iron (Fe) alloy, nickel (Ni) alloy, or the like.
  • the cross section along the first direction of the metal line MW is substantially circular, but is not limited thereto, and may be, for example, a substantially square shape.
  • the current collector foil PEP having the positive electrode mixture layer PEF applied on the surface thereof is mounted on the drying metal member MD2.
  • the current collector foil PEP is mounted on the plurality of metal wires MW of the drying metal member MD2.
  • the current collector foil PEP mounted on the drying metal member MD2 is conveyed into, for example, a 120 ° C. hot-air drying furnace, and applied to the surface of the current collector foil PEP.
  • the layer PEF is dried.
  • the conveying speed of the current collector foil PEP is, for example, 5 to 100 m / min. At the time of mass production, productivity can be maintained by conveying the drying metal member MD2 together with the current collector foil PEP in the hot air drying furnace at a constant speed.
  • the porosity of the positive electrode mixture layer PEFH that is not located on the plurality of metal wires MW of the drying metal member MD2 is reduced to the drying metal member MD2. It becomes higher than the porosity of the positive electrode mixture layer PEFL located on the plurality of metal wires MW.
  • a positive electrode mixture layer PEFL with a width of 5 mm and a low porosity and a positive electrode mixture layer PEFH with a width of 5 mm and a high porosity are alternately formed in the conveying direction of the current collector foil PEP.
  • a positive electrode is manufactured by press-compressing the dried positive electrode mixture layer PEF.
  • the negative electrode can be produced in the same manner.
  • FIG. 5 is a schematic diagram of a third example of an electrode winding body having electrodes in which two electrode mixture layers having different porosity are alternately formed in the winding direction according to a modification of the first embodiment.
  • the third example of the electrode winding body WRF includes a positive electrode PEL wound around the axis CR, separators SP1 and SP2, and a negative electrode NEL.
  • the positive electrode PEL the positive electrode mixture layer PEFH having a high porosity and the positive electrode mixture layer PEFL having a low porosity are alternately formed in the winding direction.
  • the negative electrode NEL the negative electrode mixture layer having a high porosity. NEFH and a negative electrode mixture layer NEFL having a low porosity are alternately formed in the winding direction.
  • the other side of the current collector foil PEP along the winding direction extends from one side of the current collector foil PEP along the winding direction in the direction of the can lid-can bottom.
  • a positive electrode PEL on which a positive electrode mixture layer PEFH having a high porosity reaching 1 is formed.
  • the other side of the current collector foil NEP along the winding direction from one side of the current collector foil NEP along the winding direction in the direction of the can lid-can bottom.
  • the negative electrode NEL in which the negative electrode mixture layer NEFH having a high porosity reaching the upper limit is formed.
  • FIG. 6 is a cross section of an electrode in which an electrode mixture layer having a low porosity and an electrode mixture layer having a high porosity are alternately formed according to Example 1 (cross section in the direction along the conveying direction of the current collector foil). It is a schematic diagram which expands and shows a part of.
  • FIG. 7 is a graph showing the porosity of an electrode mixture layer having a low porosity and the porosity of an electrode mixture layer having a high porosity.
  • an electrode mixture layer with a low porosity is a location (for example, a region closer to 2.5 mm from the metal wire) near the metal wire in the drying process, and an electrode mixture layer with a high porosity is used in the drying process. It is a portion that is not near the metal line (for example, a far region away from the metal wire by 2.5 mm or more).
  • the electrode EL includes a current collector (current collector foil) EP and an electrode mixture layer EF formed on the current collector EP.
  • the electrode mixture layer EF includes the active material AS. , Containing conductive aid CA and binder (binder) BD.
  • the average particle size of the active material AS is, for example, 2 to 10 ⁇ m, and the particle size distribution of the electrode mixture layer having a low porosity and the particle size distribution of the electrode mixture layer having a high porosity are the same.
  • “same” does not mean completely the same, but means substantially the same or substantially the same, and includes a certain range in consideration of variations.
  • the average particle diameter of the active material AS also has a variation of 2 to 10 ⁇ m.
  • Quantitative evaluation of the porosity can be performed, for example, by observing a cross section SEM (Scanning Electron Microscope) of the electrode mixture layer EF. From the SEM image, the void area and the solid content area of the cross section of the electrode mixture layer EF were obtained, and the void ratio was calculated by the formula (1).
  • SEM Sccanning Electron Microscope
  • Porosity (area%) Void area / (Cavity area + Solid content area) ⁇ 100 Formula (1)
  • FIG. 7 shows the porosity of the electrode mixture layer having a low porosity and the porosity of the electrode mixture layer having a high porosity.
  • the porosity shown in FIG. 7 is an average value at three locations, and the error bar indicates the maximum value and the minimum value.
  • the porosity of the electrode mixture layer with low porosity is about 18 to 28% by volume
  • the porosity of the electrode mixture layer with high porosity is about 39 to 43% by volume
  • the difference in porosity is about 11 to 25% by volume. Met.
  • the reason why the electrode mixture layer having a low porosity and the electrode mixture layer having a high porosity are obtained is considered as follows.
  • the electrode mixture layer near the metal wire has a faster temperature rise than the electrode mixture layer not near the metal wire, and the volatilization rate of NMP contained in the electrode slurry (slurry electrode material) is high. Conceivable. Therefore, NMP volatilizes and disappears in the electrode mixture layer in the vicinity of the metal wire, and NMP does not volatilize in a portion that is not in the vicinity of the metal wire. When such a state occurs, the NMP flows from the location where the NMP remains to the location where the NMP has evaporated and disappeared.
  • the solid content of the active material moves simultaneously with the flow of NMP, so the density of the solid content increases in the electrode mixture layer near the metal wire, and the solid content in the electrode mixture layer not near the metal wire. It is thought that the density is lowered. Since the solid contents have different densities, electrode mixture layers having different porosity can be formed.
  • two or more electrode mixture layers having different porosity it is only necessary to provide a temperature distribution in the electrode mixture layer in the drying step as described above, and the metal of the metal member for drying in the drying step
  • the shape of the line two or more electrode mixture layers having different porosity can be produced in an arbitrary pattern.
  • the shape of the positive electrode mixture layer PEFH having a high porosity can be a parallelogram, or as shown in FIG. 8 (b), the positive electrode mixture having a high porosity can be used.
  • the shape of the agent layer PEFH can also be corrugated.
  • FIG. 9 is a graph showing the permeation rate of the electrolytic solution in the electrode according to the first embodiment and the electrode according to the comparative example.
  • FIG. 10 is a graph showing the internal resistance in the battery including the electrode according to the first embodiment and the battery including the electrode according to the comparative example.
  • An electrode in which electrode mixture layers were alternately formed was used.
  • the active material density of the electrode mixture layer having a low porosity is about 2.8 g / cm 3
  • the active material density of the electrode mixture layer having a high porosity is about 2.1 g / cm 3.
  • the area ratio of the electrode mixture layer having a low porosity and the electrode mixture layer having a high porosity is 1: 1.
  • the active material density of the electrode mixture layer is about 2.7 g / cm 3 .
  • the electrolytic solution When 5 ⁇ l of the electrolytic solution is dropped on the surface of the electrode mixture layer, the electrolytic solution penetrates through the electrode mixture layer and spreads over the surface of the electrode mixture layer. After the spread of the electrolytic solution is maximized, it is observed that the electrolytic solution penetrates into the electrode mixture layer.
  • the permeation time time from immediately after the electrolytic droplet was dropped to the end of permeation was measured, and the permeation rate was calculated by equation (2).
  • FIG. 9 shows the permeation rate of the electrolytic solution in the electrode according to Example 1 and the electrode according to the comparative example.
  • the permeation rate of the electrode according to the comparative example is 1, and the permeation rate is shown as a relative value.
  • the penetration rate was improved by 1.2 times in the electrode according to the present Example 1.
  • the electrolyte solution is injected from the can bottom side. Time can be shortened.
  • the length (L) of the mixture layer having a high porosity formed from the bottom of the can to the can lid or from the can lid to the bottom of the can is determined from the direction of the can lid to the bottom of the can.
  • the width (W) of the electrode mixture layer is preferably 2/3 or more and 1 or less (2W / 3 ⁇ L ⁇ W) (see FIG. 3A).
  • the length (L) of the electrode mixture layer having a high porosity formed from the can bottom side toward the can lid direction or from the can lid side toward the can bottom direction is the width of the electrode mixture layer in the can lid-can bottom direction ( If the ratio is less than 2/3 times W), the electrode mixture layer in which the electrolyte solution easily penetrates becomes short, and the effect of shortening the injection time becomes low.
  • the injection time can be shortened by injecting the electrolyte from either the can bottom side or the can lid side.
  • Example 1 a positive electrode composed of a lithium manganese cobalt nickel composite oxide, a conductive additive (graphite powder) and a binder (polyvinylidene fluoride), a carbon powder, a conductive additive (graphite), and a binder A negative electrode made of a material (polyvinylidene fluoride) was used. Further, in both Example 1 and Comparative Example, an electrolytic solution comprising a separator made of porous polypropylene having a thickness of 20 ⁇ m, an organic solvent (ethyl carbonate, dimethyl carbonate or ethyl methyl carbonate), and an electrolytic salt (lithium hexafluorophosphate).
  • an electrolytic solution comprising a separator made of porous polypropylene having a thickness of 20 ⁇ m, an organic solvent (ethyl carbonate, dimethyl carbonate or ethyl methyl carbonate), and an electrolytic salt (lithium hexafluorophosphate).
  • a lithium ion battery was prepared using The prepared lithium ion battery was charged with a constant current at 1 C up to a battery voltage of 4.2 V, and then charged with a constant voltage to obtain a fully charged state. From a fully charged state, the battery was discharged at each current value of C rate: 0.2 to 20.0 C, the battery voltage after 10 seconds was measured, and the slope of the battery voltage with respect to the discharge current was calculated as the internal resistance of the battery.
  • the C rate is an expression of a current value based on a current value for discharging the battery capacity in one hour. For example, the current value when discharging over 1 hour is 1C, and the current value when discharging over 0.5 hour is 2C. The lower the internal resistance, the lower the battery voltage during discharge, which means that the battery can be discharged at a higher output.
  • FIG. 10 shows the internal resistance of the battery using the electrode according to Example 1 and the battery using the electrode according to the comparative example.
  • the internal resistance of the battery using the electrode according to the comparative example is 1, and the internal resistance is shown as a relative value. It was confirmed that the internal resistance can be reduced by about 5% in the battery using the electrode according to Example 1 as compared with the battery using the electrode according to the comparative example.
  • the permeation time of the electrolytic solution can be shortened. Furthermore, the internal resistance during charging / discharging of the lithium ion battery can be reduced. As a result, it is possible to improve both the productivity of the lithium ion battery and the battery characteristics.
  • Patent Document 1 describes a method of forming a plurality of electrode mixture layers having a high porosity along the electrode coating direction.
  • an electrode mixture layer having a high porosity is not formed in the direction of the can lid-can bottom of the electrode wound body, so that the effect of increasing the permeation rate of the electrolytic solution is small.
  • Example 1 since the electrode mixture layer having a high porosity is formed in a direction intersecting with the conveying direction of the current collector foil and the surface of the current collector foil, when the electrode is wound, FIG. ) And (b) and as shown in FIG. 5, an electrode mixture layer having a high porosity is formed in the direction of the can lid-can bottom of the electrode winding body.
  • the electrolyte solution penetrates from the bottom of the can to the can lid side or from the can lid side to the can bottom side through the electrode mixture layer having a high porosity.
  • the difference in the permeation speed in the can lid-can bottom direction between Example 1 and Patent Document 1 corresponds to the result shown in FIG.
  • Patent Document 2 an electrode mixture layer having a large void size is formed using an active material from which fine powder has been removed, and then an electrode mixture layer having a small void size using an active material from which fine powder has not been removed. A method of forming is described.
  • Patent Document 2 since an electrode mixture layer having a large gap size can be formed in the direction of the can lid-can bottom, it is possible to reduce the permeation time of the electrolytic solution.
  • the step of applying the electrode mixture is required twice, which increases the number of electrode manufacturing steps.
  • Patent Document 2 it is necessary to remove the active material in the form of fine powder.
  • the fine powder is characterized by a short diffusion distance of lithium ions in the active material and a large reaction area per weight of the active material. Therefore, removal of fine powder is disadvantageous for reducing internal resistance.
  • active material materials having the same particle size distribution are used in the electrode mixture layer having a high porosity and the electrode mixture layer having a low porosity. Therefore, since fine powder is also present in the electrode mixture layer having a low porosity, an effect of reducing internal resistance can be obtained as compared with Patent Document 2, and input / output characteristics can be improved.
  • the positive electrode mixture layer PEF is formed on the surface of the current collector foil PEP, and the negative electrode mixture layer NEF is formed on the surface of the current collector foil NEP in the same manner as in the coating step according to Example 1 described above. Form.
  • FIG. 11 (a), (b) and (c) Next, a drying process is demonstrated using FIG. 11 (a), (b) and (c).
  • the manufacturing method of the positive electrode will be described, but the manufacturing method of the negative electrode is substantially the same.
  • 11 (a), (b) and (c) respectively show a drying metal member, a positive electrode mixture layer being dried, and a positive electrode mixture layer after being dried used in the drying step after slurry application according to the second embodiment. It is a schematic diagram shown.
  • the drying metal member MD3 is a metal plate in which a plurality of recesses extending in the first direction and a plurality of recesses extending in the second direction intersecting the first direction are formed, that is, the recesses are in a lattice shape. It consists of a formed metal plate.
  • the interval (pitch) of the lattice is, for example, 10 mm, and the lattice width is, for example, 5 mm.
  • the drying metal member MD3 is made of, for example, stainless steel, iron (Fe), gold (Au), silver (Ag), iron (Fe) alloy, nickel (Ni) alloy, or the like.
  • the current collector foil PEP having the positive electrode mixture layer PEF applied on the surface thereof is mounted on the drying metal member MD3. Thereafter, the current collector foil PEP mounted on the drying metal member MD3 is conveyed into, for example, a 120 ° C. hot-air drying furnace, and applied to the surface of the current collector foil PEP. The layer PEF is dried.
  • the conveying speed of the current collector foil PEP is, for example, 5 to 100 m / min. At the time of mass production, productivity can be maintained by conveying the drying metal member MD3 together with the current collector foil PEP in a hot air drying furnace at a constant speed.
  • the porosity of the lattice-shaped positive electrode mixture layer PEF that is not located on the plurality of convex portions of the drying metal member MD3 is reduced to the drying metal. It becomes higher than the porosity of the positive electrode mixture layer PEF located on the plurality of convex portions of the member MD3.
  • a positive electrode mixture layer PEFH having a high porosity of 5 mm in width is formed in a lattice shape.
  • a positive electrode is manufactured by press-compressing the dried positive electrode mixture layer PEF.
  • the negative electrode can be produced in the same manner.
  • FIG. 12 is a schematic diagram of a fourth example of an electrode winding body having an electrode in which an electrode mixture layer in which a high porosity region according to the second embodiment has a lattice shape is formed.
  • the fourth example of the electrode winding body WRF includes a positive electrode PEL wound around the axis CR, separators SP1 and SP2, and a negative electrode NEL.
  • the positive electrode PEL the positive electrode mixture layer PEFH having a high porosity is formed in a lattice shape
  • the negative electrode NEL the negative electrode mixture layer NEFH having a high porosity is formed in a lattice shape.
  • the electrode mixture layer having a high porosity is formed in a lattice shape provided at a constant interval (pitch), but is not limited thereto.
  • a mesh shape in which electrode mixture layers having a high porosity are provided at indefinite intervals using a drying metal member on which convex portions are randomly formed.
  • the electrode mixture layer having a high porosity has a lattice shape, a wide diffusion path of lithium ions can be secured. The internal resistance during charging / discharging of the ion battery can be reduced.
  • the electrode manufacturing method according to the third embodiment will be described below.
  • the difference between the third embodiment and the first and second embodiments described above is the drying method of the electrode mixture layer formed on the surface of the current collector foil. That is, in Examples 1 and 2 described above, the electrode mixture layer after slurry application was dried with, for example, 120 ° C. hot air in a drying furnace. In Example 3, an infrared lamp was used in the drying furnace. The electrode mixture layer after slurry application is dried.
  • the positive electrode mixture layer PEF is formed on the surface of the current collector foil PEP, and the negative electrode mixture layer NEF is formed on the surface of the current collector foil NEP in the same manner as in the coating step according to Example 1 described above. Form.
  • FIGS. 13A, 13B, and 13C are schematic diagrams showing a shielding plate used in the drying step after slurry application according to Example 3, a positive electrode mixture layer being dried, and a positive electrode mixture layer after being dried, respectively.
  • FIG. 13A, 13B, and 13C are schematic diagrams showing a shielding plate used in the drying step after slurry application according to Example 3, a positive electrode mixture layer being dried, and a positive electrode mixture layer after being dried, respectively.
  • a shielding plate SH shown in FIG. 13 (a) is prepared.
  • shielding portions SHP and openings (slits) OP are alternately formed in the first direction.
  • the widths of the shielding part SHP and the opening OP in the first direction are each 1 mm, for example, and the opening OP is formed in a stripe shape extending in the second direction orthogonal to the first direction.
  • a ceramic plate or a metal plate can be used for the shielding plate SH.
  • the infrared lamp is installed through the shielding board SH in the direction facing the surface of positive mix layer PEF, and infrared rays are irradiated from an infrared lamp, and positive electrode The mixture layer PEF is dried.
  • the infrared lamp a halogen lamp or the like can be used.
  • the shielding plates SH are arranged so that the shielding portions SHP and the openings OP are alternately arranged in the conveying direction of the current collector foil PEP. That is, the shielding plate SH is disposed so that the first direction and the transport direction of the current collector foil PEP coincide with each other and the opening OP extends in a direction intersecting the transport direction of the current collector foil PEP. .
  • productivity can be maintained by transporting the shielding plate SH together with the current collector foil PEP through the drying furnace at a constant speed.
  • the porosity of the positive electrode mixture layer PEF that is shielded from infrared rays and is not irradiated is equal to the porosity of the positive electrode mixture layer PEF that is irradiated with infrared rays. Higher than.
  • a positive electrode mixture layer having a high porosity and a positive electrode mixture layer having a low porosity are alternately formed in the conveying direction of the current collector foil PEP.
  • the width of the positive electrode mixture layer having a low porosity in the transport direction of the current collector foil PEP and the width of the positive electrode mixture layer having a high porosity are, for example, 1 mm.
  • a positive electrode is manufactured by press-compressing the dried positive electrode mixture layer PEF.
  • the negative electrode can be produced in the same manner.
  • the electrode mixture layer having a high porosity was formed in the can lid-can bottom direction by laminating and winding the electrode and the separator. An electrode winding body is formed.
  • the drying method using the infrared lamp can be locally heated, and can form a pattern in which the width of the electrode mixture layer having a different porosity is narrower than the hot air drying method used in Examples 1 and 2 described above. it can. Thereby, since the diffusion path
  • the electrode mixture layers having different porosity can be formed in an arbitrary pattern (for example, FIGS. 3A and 3B, FIG. 5 or FIG.
  • the technical idea of the present invention has been described by taking a lithium ion battery as an example, but the technical idea of the present invention is not limited to the lithium ion battery.
  • an electricity storage device for example, a battery or a capacitor
  • a positive electrode for example, a positive electrode, a negative electrode, and a separator that electrically separates the positive electrode and the negative electrode.
  • the present invention can be widely used in the manufacturing industry for manufacturing batteries represented by, for example, lithium ion batteries.
  • Electrode mixture layer EL Electrode EP Current collector (current collector foil) LIB Lithium ion batteries MD1, MD2, MD3 Drying metal member MP Metal plate MW Metal wire NEF Negative electrode mixture layer NEFH High porosity negative electrode mixture layer NEFL Low porosity negative electrode mixture layer NEL Negative electrode NEP Current collector foil NT Negative electrode Lead plate NTAB Negative electrode current collector tab NR Negative electrode ring OP Opening (slit) P1 First pitch P2 Second pitch PEF Positive electrode mixture layer PEFH High porosity positive electrode mixture layer PEFL Low porosity positive electrode mixture layer PEL Positive electrode PEP Current collecting foil PR Positive electrode ring PT Positive electrode lead plate PTAB Positive electrode current collecting tab SH Shielding plate SHP Shielding part SP1, SP2 Separator WRF Electrode winding body

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Abstract

This invention comprises, in an electrode wound body wherein a positive electrode, a separator, and a negative electrode are layered and wound, forming at the positive electrode a high-porosity positive electrode mixture layer and a low-porosity positive electrode mixture layer alternating in a winding direction on the surface of a current collector foil, and, forming at the negative electrode a high-porosity negative electrode mixture layer and a low-porosity negative electrode mixture layer alternating in the winding direction on the surface of a current collector foil. By providing the high-porosity positive electrode mixture layer and the negative electrode mixture layer, the infiltration rate of the electrolytic solution into the electrode wound body is increased. In addition, by equalizing the particle size distributions for the active substances contained respectively in the high-porosity positive electrode mixture layer and the low-porosity positive electrode mixture layer, and by equalizing the particle size distributions for the active substances contained respectively in the high-porosity negative electrode mixture layer and the low-porosity negative electrode mixture layer, the internal resistance during charging-discharging is lowered.

Description

リチウムイオン電池およびその製造方法Lithium ion battery and manufacturing method thereof
　本発明は、リチウムイオン電池およびその製造方法に関する。 The present invention relates to a lithium ion battery and a manufacturing method thereof.
　本技術分野の背景技術として、特開２０１３－００８５２３号公報（特許文献１）および特開２０１１－１７５７３９号公報（特許文献２）がある。 As background art in this technical field, there are JP 2013-008523 A (Patent Document 1) and JP 2011-175739 A (Patent Document 2).
　特許文献１には、「集電体の表面に活物質を含む合剤層が形成されており、この合剤層は、集電体の表面に沿う方向の位置に応じて空隙率が異なる構成を有する電池用電極」が記載されている。 Patent Document 1 states that “a mixture layer containing an active material is formed on the surface of a current collector, and this mixture layer has a different porosity depending on the position along the surface of the current collector. The battery electrode having "" is described.
　また、特許文献２には、「電極表面に形成される電極膜を、空隙が小さく電解液が浸透しにくいが活物質の密度が大きい合剤層と、活物質の密度が小さいが電解液が浸透しやすい空隙サイズが大きい合剤層とを組み合わせた電極膜構造を有するリチウムイオン電池」が記載されている。 Patent Document 2 states that “the electrode film formed on the electrode surface is a mixture layer having a small gap and a small active material density, but a high active material density; "A lithium ion battery having an electrode film structure combined with a mixture layer having a large void size that easily penetrates" is described.
特開２０１３－００８５２３号公報JP 2013-008523 A 特開２０１１－１７５７３９号公報JP 2011-175739 A
　リチウムイオン電池には、生産性の向上と電池特性の向上との両立が求められている。 Lithium ion batteries are required to achieve both improved productivity and improved battery characteristics.
　前記特許文献１には、電極合剤層中のリチウムイオンの移動経路を確保して、入出力特性を向上させるリチウムイオン電池用電極およびその製造方法が記載されている。しかし、電解液の浸透時間に関しては言及されておらず、前記特許文献１のリチウムイオン電池用電極の構造は、電解液の浸透時間の短縮には最適ではない。 Patent Document 1 describes a lithium ion battery electrode that secures a migration path of lithium ions in an electrode mixture layer and improves input / output characteristics, and a manufacturing method thereof. However, no mention is made regarding the permeation time of the electrolytic solution, and the structure of the lithium ion battery electrode of Patent Document 1 is not optimal for shortening the permeation time of the electrolytic solution.
　また、前記特許文献２には、微粉末を除去した活物質を用いた、空隙サイズの大きい電極合剤層を電解液の供給パスとし、電解液の浸透時間の短縮を可能とするリチウムイオン電池が記載されている。しかし、微粉末は、活物質中のリチウムイオンの拡散距離が短く、また、活物質重量あたりの反応面積が大きいという特徴を持つため、微粉末を含む活物質は、入出力特性の向上に適している。そのため、微粉末を除去した活物質は、入出力特性の向上には不利である。さらに、前記特許文献２の電極膜の製造方法では、微粉末を除去する工程が増加し、電極合剤を塗布する工程も２工程に増加するため、電極の製造工程数の増加に繋がる。 Patent Document 2 discloses a lithium ion battery that uses an active material from which fine powder has been removed and uses an electrode mixture layer having a large void size as an electrolyte solution supply path, thereby reducing the electrolyte solution penetration time. Is described. However, since fine powder has the characteristics that the diffusion distance of lithium ions in the active material is short and the reaction area per active material weight is large, the active material containing fine powder is suitable for improving input / output characteristics. ing. Therefore, an active material from which fine powder has been removed is disadvantageous for improving input / output characteristics. Furthermore, in the method for producing an electrode film of Patent Document 2, the number of steps for removing fine powder increases and the number of steps for applying an electrode mixture increases to two, leading to an increase in the number of electrode production steps.
　そこで、本発明は、電解液の浸透時間を短縮し、かつ、充放電時の内部抵抗を低減することにより、生産性の向上と電池特性の向上との両立を図ることのできるリチウムイオン電池およびその製造方法を提供する。 Therefore, the present invention provides a lithium ion battery capable of achieving both improvement in productivity and improvement in battery characteristics by shortening the permeation time of the electrolytic solution and reducing the internal resistance during charging and discharging. A manufacturing method thereof is provided.
　上記課題を解決するために、本発明によるリチウムイオン電池は、互いに対向する位置に缶蓋と缶底とを有する外装缶の内部に、積層された正極と、セパレータと、負極とを軸心の回りに捲回した電極捲回体を有する。そして、正極では、集電箔の表面上に、空隙率の高い正極合剤層と空隙率の低い正極合剤層とが捲回方向に交互に形成され、負極では、集電箔の表面上に、空隙率の高い負極合剤層と空隙率の低い負極合剤層とが捲回方向に交互に形成される。さらに、空隙率の高い正極合剤層と空隙率の低い正極合剤層のそれぞれに含まれる活物質の粒度分布は同じであり、空隙率の高い負極合剤層と空隙率の低い負極合剤層のそれぞれに含まれる活物質の粒度分布は同じである。 In order to solve the above-mentioned problems, a lithium ion battery according to the present invention has a positive electrode, a separator, and a negative electrode that are stacked in an outer can having a can lid and a can bottom at positions facing each other. An electrode winding body wound around is provided. In the positive electrode, a positive electrode mixture layer having a high porosity and a positive electrode mixture layer having a low porosity are alternately formed in the winding direction on the surface of the current collector foil. In addition, a negative electrode mixture layer having a high porosity and a negative electrode mixture layer having a low porosity are alternately formed in the winding direction. Furthermore, the particle size distribution of the active material contained in each of the positive electrode mixture layer having a high porosity and the positive electrode mixture layer having a low porosity is the same, and the negative electrode mixture layer having a high porosity and the negative electrode mixture having a low porosity are used. The particle size distribution of the active material contained in each of the layers is the same.
　本発明によれば、生産性の向上と電池特性の向上との両立を図ることのできるリチウムイオン電池およびその製造方法を提供することができる。 According to the present invention, it is possible to provide a lithium ion battery and a method for manufacturing the same that can achieve both improvement in productivity and improvement in battery characteristics.
　上記した以外の課題、構成および効果は、以下の実施の形態の説明により明らかにされる。 Issues, configurations, and effects other than those described above will be clarified by the following description of embodiments.
実施例１による円筒形のリチウムイオン電池の内部構造を示す断面図である。2 is a cross-sectional view showing an internal structure of a cylindrical lithium ion battery according to Example 1. FIG. （ａ）、（ｂ）および（ｃ）はそれぞれ、実施例１によるスラリー塗布後の乾燥工程で用いる乾燥用金属部材、乾燥中の正極合剤層および乾燥後の正極合剤層を示す模式図である。(A), (b) and (c) are schematic views showing a metal member for drying used in the drying step after slurry application according to Example 1, a positive electrode mixture layer during drying, and a positive electrode mixture layer after drying, respectively. It is. （ａ）および（ｂ）はそれぞれ、実施例１による互いに空隙率が異なる２つの電極合剤層が捲回方向に交互に形成された電極捲回体の第１例および第２例の模式図である。(A) And (b) is the schematic diagram of the 1st example and 2nd example of the electrode winding body by which the two electrode mixture layers by which the porosity from Example 1 differs mutually were formed alternately in the winding direction, respectively It is. （ａ）、（ｂ）および（ｃ）はそれぞれ、実施例１の変形例によるスラリー塗布後の乾燥工程で用いる乾燥用金属部材、乾燥中の正極合剤層および乾燥後の正極合剤層を示す模式図である。(A), (b), and (c) are a drying metal member, a positive electrode mixture layer being dried, and a positive electrode mixture layer after drying, respectively, used in the drying step after slurry application according to the modification of Example 1. It is a schematic diagram shown. 実施例１の変形例による互いに空隙率が異なる２つの電極合剤層が捲回方向に交互に形成された電極捲回体の第３例の模式図である。It is a schematic diagram of the 3rd example of the electrode winding body by which the two electrode mixture layers by which the porosity is mutually different by the modification of Example 1 were alternately formed in the winding direction. 実施例１による空隙率の低い電極合剤層と空隙率の高い電極合剤層とが交互に形成された電極の断面の一部を拡大して示す模式図である。It is a schematic diagram which expands and shows a part of cross section of the electrode by which the electrode mixture layer with a low porosity by Example 1 and the electrode mixture layer with a high porosity were formed alternately. 空隙率の低い電極合剤層の空隙率および空隙率の高い電極合剤層の空隙率を示すグラフ図である。It is a graph which shows the porosity of the electrode mixture layer with a low porosity, and the porosity of an electrode mixture layer with a high porosity. （ａ）および（ｂ）は、実施例１による互いに空隙率が異なる２つの正極合剤層の他の例を示す要部平面図である。(A) And (b) is a principal part top view which shows the other example of two positive mix layers from which the porosity in Example 1 differs. 実施例１による電極および比較例による電極における電解液の浸透速度を示すグラフ図である。It is a graph which shows the osmosis | permeation rate of the electrolyte solution in the electrode by Example 1, and the electrode by a comparative example. 実施例１による電極を備える電池および比較例による電極を備える電池における内部抵抗を示すグラフ図である。It is a graph which shows the internal resistance in a battery provided with the electrode provided with the electrode by Example 1, and the battery provided with the comparative example. （ａ）、（ｂ）および（ｃ）はそれぞれ、実施例２によるスラリー塗布後の乾燥工程で用いる乾燥用金属部材、乾燥中の正極合剤層および乾燥後の正極合剤層を示す模式図である。(A), (b) and (c) are schematic diagrams showing a drying metal member, a positive electrode mixture layer being dried, and a positive electrode mixture layer after drying, respectively, used in the drying step after slurry application according to Example 2. It is. 実施例２による空隙率が高い領域が格子形状に形成された電極を有する電極捲回体の第４例の模式図である。It is a schematic diagram of the 4th example of the electrode winding body which has the electrode in which the area | region with the high porosity by Example 2 was formed in the grid | lattice form. （ａ）、（ｂ）および（ｃ）はそれぞれ、実施例３によるスラリー塗布後の乾燥工程で用いる遮蔽板、乾燥中の正極合剤層および乾燥後の正極合剤層を示す模式図である。(A), (b), and (c) are the schematic diagrams which respectively show the shielding board used at the drying process after slurry application | coating by Example 3, the positive mix layer during drying, and the positive mix layer after drying. .
　以下の実施の形態において、便宜上その必要があるときは、複数のセクションまたは実施の形態に分割して説明するが、特に明示した場合を除き、それらはお互いに無関係なものではなく、一方は他方の一部または全部の変形例、詳細、補足説明等の関係にある。 In the following embodiments, when necessary for the sake of convenience, the description will be divided into a plurality of sections or embodiments. However, unless otherwise specified, they are not irrelevant to each other, and one is the other. There are some or all of the modifications, details, supplementary explanations, and the like.
　また、以下の実施の形態において、要素の数等（個数、数値、量、範囲等を含む）に言及する場合、特に明示した場合および原理的に明らかに特定の数に限定される場合等を除き、その特定の数に限定されるものではなく、特定の数以上でも以下でも良い。 Further, in the following embodiments, when referring to the number of elements (including the number, numerical value, quantity, range, etc.), especially when clearly indicated and when clearly limited to a specific number in principle, etc. Except, it is not limited to the specific number, and may be more or less than the specific number.
　また、以下の実施の形態において、その構成要素（要素ステップ等も含む）は、特に明示した場合および原理的に明らかに必須であると考えられる場合等を除き、必ずしも必須のものではないことは言うまでもない。 Further, in the following embodiments, the constituent elements (including element steps) are not necessarily indispensable unless otherwise specified and clearly considered essential in principle. Needless to say.
　また、「Ａからなる」、「Ａよりなる」、「Ａを有する」、「Ａを含む」と言うときは、特にその要素のみである旨明示した場合等を除き、それ以外の要素を排除するものでないことは言うまでもない。同様に、以下の実施の形態において、構成要素等の形状、位置関係等に言及するときは、特に明示した場合および原理的に明らかにそうでないと考えられる場合等を除き、実質的にその形状等に近似または類似するもの等を含むものとする。このことは、上記数値および範囲についても同様である。 In addition, when referring to “consisting of A”, “consisting of A”, “having A”, and “including A”, other elements are excluded unless specifically indicated that only that element is included. It goes without saying that it is not what you do. Similarly, in the following embodiments, when referring to the shapes, positional relationships, etc. of the components, etc., the shapes are substantially the same unless otherwise specified, or otherwise apparent in principle. And the like are included. The same applies to the above numerical values and ranges.
　また、以下の実施の形態で用いる図面においては、平面図であっても図面を見易くするためにハッチングを付す場合もある。また、以下の実施の形態を説明するための全図において、同一機能を有するものは原則として同一の符号を付し、その繰り返しの説明は省略する。以下、本実施の形態を図面に基づいて詳細に説明する。 Also, in the drawings used in the following embodiments, hatching may be added to make the drawings easy to see even if they are plan views. In all the drawings for explaining the following embodiments, components having the same function are denoted by the same reference numerals in principle, and repeated description thereof is omitted. Hereinafter, the present embodiment will be described in detail with reference to the drawings.
　以下の説明では、正極および負極を総括して「電極」と呼び、正極合剤および負極合剤を総括して「電極合剤」と呼ぶ。また、以下の説明では、乾燥炉を用いた乾燥工程前の正極材料、負極材料、および絶縁材料は、結着材溶液および有機溶剤などの液体を含み、流動性を有する物質である。また、以下の説明で「集電箔の表面」という場合は、集電箔の表側の面および裏側の面を含めた全面ではなく、表側の面のみを指すものとする。 In the following description, the positive electrode and the negative electrode are collectively referred to as “electrode”, and the positive electrode mixture and the negative electrode mixture are collectively referred to as “electrode mixture”. In the following description, the positive electrode material, the negative electrode material, and the insulating material before the drying process using the drying furnace are substances having fluidity including liquids such as a binder solution and an organic solvent. In the following description, “the surface of the current collector foil” refers to only the front surface, not the entire surface including the front surface and the back surface of the current collector foil.
　≪リチウムイオン電池の構成≫
　本実施例１によるリチウムイオン電池の構成の一例について、図１を用いて説明する。図１は、本実施例１による円筒形のリチウムイオン電池の内部構造を示す断面図である。 ≪Configuration of lithium-ion battery≫
An example of the configuration of the lithium ion battery according to the first embodiment will be described with reference to FIG. FIG. 1 is a cross-sectional view showing the internal structure of a cylindrical lithium ion battery according to the first embodiment.
　図１に示すように、リチウムイオン電池ＬＩＢは、底部を有する円筒形の外装缶ＣＳを有し、その外装缶ＣＳの内部には、正極ＰＥＬとセパレータＳＰ１、ＳＰ２と負極ＮＥＬとからなる電極捲回体ＷＲＦが形成されている。具体的には、電極捲回体ＷＲＦは、正極ＰＥＬと負極ＮＥＬとの間にセパレータＳＰ１（またはＳＰ２）を挟むように積層され、外装缶ＣＳの中心部にある軸芯ＣＲの回りに捲回されている。 As shown in FIG. 1, the lithium ion battery LIB has a cylindrical outer can CS having a bottom, and inside the outer can CS, an electrode container made up of a positive electrode PEL, separators SP1, SP2, and a negative electrode NEL. A circular WRF is formed. Specifically, the electrode winding body WRF is laminated so as to sandwich the separator SP1 (or SP2) between the positive electrode PEL and the negative electrode NEL, and is wound around the axis CR at the center of the outer can CS. Has been.
　そして、正極ＰＥＬに形成されている正極集電タブＰＴＡＢは、電極捲回体ＷＲＦの上部側に配置され、外装缶ＣＳの上部に設けられている正極リード板ＰＴと電気的に接続されている。一方、負極ＮＥＬに形成されている負極集電タブＮＴＡＢは、電極捲回体ＷＲＦの下部側に配置され、外装缶ＣＳの下部（底部）に設けられている負極リード板ＮＴと電気的に接続されている。 And the positive electrode current collection tab PTAB formed in the positive electrode PEL is arrange | positioned at the upper part side of the electrode winding body WRF, and is electrically connected with the positive electrode lead board PT provided in the upper part of the armored can CS. . On the other hand, the negative electrode current collecting tab NTAB formed on the negative electrode NEL is disposed on the lower side of the electrode winding body WRF and is electrically connected to the negative electrode lead plate NT provided on the lower part (bottom part) of the outer can CS. Has been.
　外装缶ＣＳの内部に形成されている電極捲回体ＷＲＦの内部には電解液が注入されている。そして、外装缶ＣＳは、電池蓋ＣＡＰにより密閉されている。外装缶ＣＳは、例えば鉄（Ｆｅ）またはステンレスを主材料としている。なお、図１中、符号ＰＲは正極リングを示し、符号ＮＲは負極リングを示す。 The electrolyte is injected into the electrode winding body WRF formed inside the outer can CS. The outer can CS is sealed with a battery lid CAP. The outer can CS is made mainly of, for example, iron (Fe) or stainless steel. In FIG. 1, the symbol PR indicates a positive electrode ring, and the symbol NR indicates a negative electrode ring.
　正極ＰＥＬは、正極活物質、結着材（バインダ）および導電助剤からなる正極合剤層ＰＥＦが集電箔ＰＥＰに塗着されて形成されている。 The positive electrode PEL is formed by applying a positive electrode mixture layer PEF made of a positive electrode active material, a binder (binder) and a conductive additive to the current collector foil PEP.
　正極活物質としては、例えばコバルト酸リチウム、ニッケル酸リチウムまたはマンガン酸リチウムなどが挙げられるが、これらに限定されるものではない。具体的に、正極活物質としては、リチウムイオンを挿入・脱離可能な材料であり、予め充分な量のリチウム（Ｌｉ）を挿入したリチウム含有遷移金属酸化物であればよく、遷移金属として、マンガン（Ｍｎ）、ニッケル（Ｎｉ）、コバルト（Ｃｏ）若しくは鉄（Ｆｅ）などの単体、または２種類以上の遷移金属を主成分とする材料であってもよい。また、スピネル結晶構造または層状結晶構造などの結晶構造についても、上述したサイトとチャンネルが確保されるものであれば特に限定されない。さらに、結晶中の遷移金属またはリチウム（Ｌｉ）の一部を鉄（Ｆｅ）、コバルト（Ｃｏ）、ニッケル（Ｎｉ）、クロム（Ｃｒ）、アルミニウム（Ａｌ）若しくはマンガン（Ｍｇ）などの元素で置換した材料を正極活物質として使用してもよい。または、結晶中に鉄（Ｆｅ）、コバルト（Ｃｏ）、ニッケル（Ｎｉ）、クロム（Ｃｒ）、アルミニウム（Ａｌ）若しくはマンガン（Ｍｇ）などの元素をドープした材料を正極活物質として使用してもよい。 Examples of the positive electrode active material include, but are not limited to, lithium cobaltate, lithium nickelate, and lithium manganate. Specifically, the positive electrode active material is a material capable of inserting / extracting lithium ions, and may be any lithium-containing transition metal oxide in which a sufficient amount of lithium (Li) has been previously inserted. It may be a simple substance such as manganese (Mn), nickel (Ni), cobalt (Co) or iron (Fe), or a material mainly composed of two or more kinds of transition metals. Further, the crystal structure such as the spinel crystal structure or the layered crystal structure is not particularly limited as long as the above-described site and channel are ensured. Furthermore, some transition metals or lithium (Li) in the crystal are replaced with elements such as iron (Fe), cobalt (Co), nickel (Ni), chromium (Cr), aluminum (Al) or manganese (Mg). The obtained material may be used as the positive electrode active material. Alternatively, a material doped with an element such as iron (Fe), cobalt (Co), nickel (Ni), chromium (Cr), aluminum (Al) or manganese (Mg) in the crystal may be used as the positive electrode active material. Good.
　結着剤は、例えばポリフッ化ビニル、ポリフッ化ビニリデンまたはポリテトラフルオロエチレンなどを使用することができる。さらに、集電箔ＰＥＰには、例えばアルミニウム（Ａｌ）などの導電性金属からなる金属箔または網状金属などが使用される。 As the binder, for example, polyvinyl fluoride, polyvinylidene fluoride, polytetrafluoroethylene, or the like can be used. Furthermore, for the current collector foil PEP, for example, a metal foil or a net-like metal made of a conductive metal such as aluminum (Al) is used.
　負極ＮＥＬは、負極活物質、結着材（バインダ）および導電助剤からなる負極合剤層ＮＥＦが集電箔ＮＥＰに塗着されて形成されている。 The negative electrode NEL is formed by applying a negative electrode mixture layer NEF made of a negative electrode active material, a binder (binder) and a conductive additive to the current collector foil NEP.
　負極活物質としては、例えば結晶質の炭素材料または非晶質の炭素材料などが挙げられるが、これらに限定されたものではない。具体的に、負極活物質としては、リチウムイオンを挿入・脱離可能な炭素材料であればよく、天然黒鉛、人造の各種黒鉛剤またはコークスなどの炭素材料を使用することができる。さらに、上記の炭素材料の他に、酸化シリコン、酸化ニオブ若しくは酸化チタン等の酸化物、またはシリコン（Ｓｉ）、スズ（Ｓｎ）、ゲルマニウム（Ｇｅ）、鉛（Ｐｂ）若しくはアルミニウム（Ａｌ）などに代表されるリチウム（Ｌｉ）と合金を形成する材料、またはこれらの混合物を使用することができる。そして、その粒子形状においても、鱗片状、球状、繊維状または塊状など様々な粒子形状のものが適用可能である。 Examples of the negative electrode active material include a crystalline carbon material and an amorphous carbon material, but are not limited thereto. Specifically, the negative electrode active material may be any carbon material that can insert and desorb lithium ions, and carbon materials such as natural graphite, various artificial graphite agents, and coke can be used. In addition to the above carbon materials, oxides such as silicon oxide, niobium oxide or titanium oxide, or silicon (Si), tin (Sn), germanium (Ge), lead (Pb) or aluminum (Al) A material that forms an alloy with lithium (Li), which is typified, or a mixture thereof can be used. And also in the particle shape, various particle shapes such as a scale shape, a spherical shape, a fiber shape or a lump shape are applicable.
　結着剤は、例えばポリフッ化ビニリデンまたはポリテトラフルオロエチレンなどを使用することができる。さらに、集電箔ＮＥＰには、例えば銅（Ｃｕ）などの導電性金属からなる金属箔または網状金属などが使用される。 As the binder, for example, polyvinylidene fluoride or polytetrafluoroethylene can be used. Furthermore, for the current collector foil NEP, for example, a metal foil or a net-like metal made of a conductive metal such as copper (Cu) is used.
　セパレータＳＰ１，ＳＰ２は、正極と負極との間を絶縁し、電気的な接触を防止しつつ、リチウムイオンを通過させるスペーサとしての機能を有している。近年では、このセパレータＳＰ１，ＳＰ２として、高強度で薄い微多孔質膜が使用されている。この微多孔質膜から構成されるセパレータＳＰ１，ＳＰ２としては、例えばポリエチレン（ＰＥ（polyethylene））若しくはポリプロピレン（ＰＰ（polypropylene））、またはこれらの材料の組み合わせから構成されている。 The separators SP1 and SP2 have a function as a spacer that allows lithium ions to pass through while insulating between the positive electrode and the negative electrode and preventing electrical contact. In recent years, high-strength and thin microporous membranes are used as the separators SP1 and SP2. The separators SP1 and SP2 composed of the microporous membrane are composed of, for example, polyethylene (PE (polyethylene)) or polypropylene (PP (polypropylene)), or a combination of these materials.
　正極と負極との間で充放電反応が行われる電解液には、非水電解液が使用される。リチウムイオン電池ＬＩＢは、活物質でのリチウムイオンの挿入・脱離を利用して充放電を行う電池であり、電解液中をリチウムイオンが移動する。リチウムは、強い還元剤であり、水と激しく反応して水素ガスを発生する。従って、リチウムイオンが電解液中を移動するリチウムイオン電池ＬＩＢでは、従来の電池のように水溶液を電解液に使用することができない。このことから、リチウムイオン電池ＬＩＢでは、電解液として非水電解液が使用される。 A nonaqueous electrolytic solution is used as an electrolytic solution in which a charge / discharge reaction is performed between the positive electrode and the negative electrode. The lithium ion battery LIB is a battery that performs charging / discharging by using insertion / extraction of lithium ions in an active material, and lithium ions move in an electrolytic solution. Lithium is a strong reducing agent and reacts violently with water to generate hydrogen gas. Therefore, in the lithium ion battery LIB in which lithium ions move in the electrolytic solution, an aqueous solution cannot be used as the electrolytic solution as in the conventional battery. For this reason, in the lithium ion battery LIB, a non-aqueous electrolyte is used as the electrolyte.
　具体的に、非水電解液の電解質としては、ＬｉＰＦ６、ＬｉＣｌＯ４、ＬｉＡｓＦ６、ＬｉＢＦ４、ＬｉＢ（Ｃ６Ｈ５）４、ＣＨ３ＳＯ３Ｌｉ若しくはＣＦ３ＳＯ３Ｌｉなど、またはこれらの混合物を使用することができる。また、有機溶媒としては、エチレンカーボネート、ジメチルカーボネート、エチルメチルカーボネート、プロピレンカーボネートまたはジエチルカーボネートを使用することができる。さらに、有機溶媒としては、１，２－ジメトキシエタン、１，２－ジエトキシエタン、γ－ブチロラクトン、テトラヒドロフラン、１，３－ジオキソラン、４－メチル－１，３ジオキソラン、ジエチルエーテル、スルホラン、メチルスルホラン、アセトニトリルまたはプロピオニトリルなどを使用することができる。さらに、有機溶媒としては、上記した有機溶媒の混合液を使用することができる。 Specifically, as the electrolyte of the nonaqueous electrolyte, LiPF 6, LiClO 4, LiAsF 6, LiBF 4, LiB (C 6 H 5) 4, such as CH 3 SO 3 Li or CF 3 SO 3 Li, or their Mixtures can be used. Moreover, as an organic solvent, ethylene carbonate, dimethyl carbonate, ethyl methyl carbonate, propylene carbonate, or diethyl carbonate can be used. Further, examples of the organic solvent include 1,2-dimethoxyethane, 1,2-diethoxyethane, γ-butyrolactone, tetrahydrofuran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, diethyl ether, sulfolane, methylsulfolane. Acetonitrile or propionitrile can be used. Furthermore, as the organic solvent, the above-mentioned mixed liquid of organic solvents can be used.
　ところで、電解液の注液方法の一例としては、電解液を缶底側から注液し、電極捲回体ＷＲＦの缶底側から缶蓋側に向かって電解液を浸透させる方法、または電解液を缶蓋側から注液し、電極捲回体ＷＲＦの缶蓋側から缶底側に向かって電解液を浸透させる方法がある。注液時間を短縮するためには、電極捲回体ＷＲＦの缶蓋－缶底方向（缶蓋から缶底へ向かう方向または缶底から缶蓋に向かう方向）に電解液が浸透しやすい経路を設けることが有効である。そこで、本実施例１では、電解液が浸透しやすい経路として、電極合剤層の一部に、電極捲回体ＷＲＦの缶蓋－缶底方向に空隙率の高い電極合剤層、例えば４０体積％程度の空隙率を有する電極合剤層を形成した。 By the way, as an example of a method for injecting the electrolytic solution, a method of injecting the electrolytic solution from the can bottom side and infiltrating the electrolytic solution from the can bottom side of the electrode winding body WRF toward the can lid side, or the electrolytic solution Is injected from the can lid side, and the electrolyte solution penetrates from the can lid side of the electrode winding body WRF toward the can bottom side. In order to shorten the injection time, the electrode winding body WRF has a path through which the electrolyte can easily penetrate in the direction of the can lid-can bottom (the direction from the can lid to the can bottom or the direction from the can bottom to the can lid). It is effective to provide it. Therefore, in Example 1, as a path through which the electrolytic solution easily permeates, an electrode mixture layer having a high porosity in the direction of the can lid-can bottom of the electrode winding body WRF, for example 40 An electrode mixture layer having a porosity of about volume% was formed.
　本実施例１によるリチウムイオン電池の特徴的な電極構造およびその製造方法を以下に詳細に説明する。 The characteristic electrode structure of the lithium ion battery according to Example 1 and the manufacturing method thereof will be described in detail below.
　≪リチウムイオン電池用電極の特徴≫
　本実施例１によるリチウムイオン電池用電極の特徴の詳細をその製造方法および評価方法の一例とともに説明する。本実施例１では、以下に説明する乾燥工程を経ることにより、捲回方向に、空隙率が互いに異なる２以上の電極合剤層が形成されたリチウムイオン電池用電極が形成される。さらに、空隙率が互いに異なる２以上の電極合剤層のそれぞれは、捲回方向に沿った集電箔の一方の辺側から捲回方向に沿った集電箔の他方の辺側に向かって形成される。 ≪Characteristics of electrode for lithium ion battery≫
Details of the characteristics of the electrode for a lithium ion battery according to the first embodiment will be described together with an example of a manufacturing method and an evaluation method thereof. In Example 1, a lithium ion battery electrode in which two or more electrode mixture layers having different porosities are formed in the winding direction is formed through a drying process described below. Further, each of the two or more electrode mixture layers having different porosity from one side of the current collector foil along the winding direction toward the other side of the current collector foil along the winding direction. It is formed.
　（電極および電極捲回体の製造方法）
　本実施例１による電極および電極捲回体の製造方法について、以下に説明する。 (Electrode and electrode winding body manufacturing method)
The manufacturing method of the electrode and electrode winding body according to the first embodiment will be described below.
　（１）まず、塗工工程について説明する。ここでは、正極合剤層の製造方法について説明するが、負極合剤層の製造方法もほぼ同様である。 (1) First, the coating process will be described. Here, although the manufacturing method of a positive mix layer is demonstrated, the manufacturing method of a negative mix layer is also the same.
　正極を構成する材料として、正極活物質にリチウムマンガンコバルトニッケル複合酸化物、導電助剤に黒鉛粉末、結着材にポリフッ化ビニリデン（ＰＶＤＦ（polyvinylidene difluoride））、および集電箔にアルミニウム箔を使用する。正極活物質、導電助剤および結着材の重量％がそれぞれ９３．０、３．５および３．５となるようにこれらを混合し、さらにＮ－メチル－２－ピロリドン（ＮＭＰ（N-methylpyrrolidone）；以下、単にＮＭＰと記す）中に分散させることで、正極スラリー（スラリー状の正極材料）を作製する。このとき、固形分比率（スラリー重量に対する固形分（正極活物質、導電助剤および結着材）の重量）が６６重量％となるようにＮＭＰの重量を調整し、スラリー粘度を１Ｐａ・ｓに調整する。上記正極スラリーを集電箔の表面上に塗布することにより、正極スラリーが均一密度で塗布された正極合剤層を集電箔の表面上に形成することができる。 Lithium manganese cobalt nickel composite oxide for the positive electrode active material, graphite powder for the conductive additive, polyvinylidene fluoride (PVDF) for the binder, and aluminum foil for the current collector foil To do. These were mixed so that the weight percentages of the positive electrode active material, the conductive additive and the binder were 93.0, 3.5 and 3.5, respectively, and further N-methyl-2-pyrrolidone (NMP (N-methylpyrrolidone ); Hereinafter simply referred to as NMP) to produce a positive electrode slurry (slurry positive electrode material). At this time, the weight of NMP is adjusted so that the solid content ratio (weight of the solid content (positive electrode active material, conductive additive and binder) with respect to the slurry weight) is 66% by weight, and the slurry viscosity is 1 Pa · s. adjust. By apply | coating the said positive electrode slurry on the surface of current collection foil, the positive mix layer by which the positive electrode slurry was apply | coated by uniform density can be formed on the surface of current collection foil.
　（２）次に、乾燥工程について、図２（ａ）、（ｂ）および（ｃ）を用いて説明する。ここでは、正極の製造方法について説明するが、負極の製造方法もほぼ同様である。図２（ａ）、（ｂ）および（ｃ）はそれぞれ、本実施例１によるスラリー塗布後の乾燥工程で用いる乾燥用金属部材、乾燥中の正極合剤層および乾燥後の正極合剤層を示す模式図である。 (2) Next, the drying process will be described with reference to FIGS. 2 (a), (b) and (c). Here, the manufacturing method of the positive electrode will be described, but the manufacturing method of the negative electrode is substantially the same. 2 (a), 2 (b), and 2 (c) show a drying metal member, a positive electrode mixture layer during drying, and a positive electrode mixture layer after drying, respectively, used in the drying step after slurry application according to the first embodiment. It is a schematic diagram shown.
　まず、図２（ａ）に示す、乾燥用金属部材ＭＤ１を準備する。乾燥用金属部材ＭＤ１は、第１方向に第１ピッチＰ１を有して配置された複数の金属線ＭＷと、複数の金属線ＭＷの一方の端部と接続する金属板ＭＰとからなる。すなわち、金属板ＭＰと複数の金属線ＭＷとは一体に形成されており、複数の金属線ＭＷは、金属板ＭＰによって固定されている。複数の金属線ＭＷの線幅は、例えば０．１～１．０ｍｍであり、複数の金属線ＭＷの第１方向の第１ピッチＰ１は、例えば１０ｍｍである。乾燥用金属部材ＭＤ１（金属板ＭＰおよび複数の金属線ＭＷ）は、例えばステンレス、鉄（Ｆｅ）、金（Ａｕ）、銀（Ａｇ）、鉄（Ｆｅ）合金またはニッケル（Ｎｉ）合金などからなる。金属線ＭＷの第１方向に沿った断面は略円形状であるが、これに限定されるものではなく、例えば略四角形状であってもよい。 First, a drying metal member MD1 shown in FIG. 2 (a) is prepared. The drying metal member MD1 includes a plurality of metal lines MW arranged with a first pitch P1 in the first direction, and a metal plate MP connected to one end of the plurality of metal lines MW. That is, the metal plate MP and the plurality of metal wires MW are integrally formed, and the plurality of metal wires MW are fixed by the metal plate MP. The line width of the plurality of metal lines MW is, for example, 0.1 to 1.0 mm, and the first pitch P1 in the first direction of the plurality of metal lines MW is, for example, 10 mm. The drying metal member MD1 (the metal plate MP and the plurality of metal wires MW) is made of, for example, stainless steel, iron (Fe), gold (Au), silver (Ag), iron (Fe) alloy, nickel (Ni) alloy, or the like. . The cross section along the first direction of the metal line MW is substantially circular, but is not limited thereto, and may be, for example, a substantially square shape.
　次に、図２（ｂ）に示すように、その表面上に正極合剤層ＰＥＦが塗布された集電箔ＰＥＰを、乾燥用金属部材ＭＤ１上に搭載する。この際、集電箔ＰＥＰの搬送方向に沿った２つの辺のうち一方の辺が、乾燥用金属部材ＭＤ１の金属板ＭＰ上に載るように、集電箔ＰＥＰは搭載される。すなわち、上記第１方向と集電箔ＰＥＰの搬送方向とは一致する。その後、乾燥用金属部材ＭＤ１上に搭載された集電箔ＰＥＰを、例えば１２０℃の熱風乾燥炉内に搬送して、集電箔ＰＥＰの表面上に塗布された、スラリー塗布後の正極合剤層ＰＥＦを乾燥させる。集電箔ＰＥＰの搬送速度は、例えば５～１００ｍ／分である。量産製造時には、乾燥用金属部材ＭＤ１を集電箔ＰＥＰと共に熱風乾燥炉中を一定速度で搬送することにより、生産性を維持することができる。 Next, as shown in FIG. 2B, the current collector foil PEP having the positive electrode mixture layer PEF applied on the surface thereof is mounted on the metal member MD1 for drying. At this time, the current collector foil PEP is mounted such that one of the two sides along the conveying direction of the current collector foil PEP is placed on the metal plate MP of the drying metal member MD1. That is, the first direction coincides with the conveying direction of the current collector foil PEP. Thereafter, the current collector foil PEP mounted on the drying metal member MD1 is conveyed into, for example, a 120 ° C. hot-air drying furnace, and applied to the surface of the current collector foil PEP. The layer PEF is dried. The conveying speed of the current collector foil PEP is, for example, 5 to 100 m / min. At the time of mass production, productivity can be maintained by conveying the drying metal member MD1 together with the current collector foil PEP in the hot air drying furnace at a constant speed.
　上記乾燥工程を経ることにより、図２（ｃ）に示すように、乾燥用金属部材ＭＤ１の金属板ＭＰ上および複数の金属線ＭＷ上に位置しなかった正極合剤層ＰＥＦＨの空隙率が、乾燥用金属部材ＭＤ１の金属板ＭＰ上および複数の金属線ＭＷ上に位置した正極合剤層ＰＥＦＬの空隙率よりも高くなる。これにより、例えば幅５ｍｍの空隙率の低い正極合剤層ＰＥＦＬと幅５ｍｍの空隙率の高い正極合剤層ＰＥＦＨとが、交互に集電箔ＰＥＰの搬送方向に形成される。また、集電箔ＰＥＰの搬送方向に沿った集電箔ＰＥＰの一方の辺から所定の幅を有する部分（集電箔ＰＥＰと金属板ＭＰとが重なった部分）に、空隙率の低い正極合剤層ＰＥＦＬが形成される。その後、乾燥した正極合剤層ＰＥＦをプレス圧縮することにより、正極が製造される。負極も同様に製造することができる。 By passing through the drying step, as shown in FIG. 2 (c), the porosity of the positive electrode mixture layer PEFH that is not located on the metal plate MP and the plurality of metal wires MW of the metal member MD1 for drying, It becomes higher than the porosity of the positive electrode mixture layer PEFL located on the metal plate MP and the plurality of metal wires MW of the drying metal member MD1. Thereby, for example, a positive electrode mixture layer PEFL with a width of 5 mm and a low porosity and a positive electrode mixture layer PEFH with a width of 5 mm and a high porosity are alternately formed in the conveying direction of the current collector foil PEP. In addition, a positive electrode composite having a low porosity is formed on a portion having a predetermined width from one side of the current collector foil PEP along the conveying direction of the current collector foil PEP (a portion where the current collector foil PEP and the metal plate MP overlap). The agent layer PEFL is formed. Then, a positive electrode is manufactured by press-compressing the dried positive electrode mixture layer PEF. The negative electrode can be produced in the same manner.
　（３）次に、捲回工程について、図３（ａ）および（ｂ）を用いて説明する。図３（ａ）および（ｂ）はそれぞれ、本実施例１による互いに空隙率が異なる２つの電極合剤層が捲回方向に交互に形成された電極を有する電極捲回体の第１例および第２例の模式図である。 (3) Next, the winding process will be described with reference to FIGS. 3 (a) and 3 (b). 3 (a) and 3 (b) respectively show a first example of an electrode winding body having electrodes in which two electrode mixture layers having different porosities according to Example 1 are alternately formed in the winding direction. It is a schematic diagram of the 2nd example.
　図３（ａ）に示すように、電極捲回体ＷＲＦの第１例は、軸心ＣＲの回りに捲回された正極ＰＥＬ、セパレータＳＰ１，ＳＰ２および負極ＮＥＬから構成される。そして、正極ＰＥＬでは、空隙率の高い正極合剤層ＰＥＦＨと空隙率の低い正極合剤層ＰＥＦＬとが捲回方向に交互に形成されており、負極ＮＥＬでは、空隙率の高い負極合剤層ＮＥＦＨと空隙率の低い負極合剤層ＮＥＦＬとが捲回方向に交互に形成されている。 As shown in FIG. 3A, the first example of the electrode winding body WRF includes a positive electrode PEL wound around the axis CR, separators SP1 and SP2, and a negative electrode NEL. In the positive electrode PEL, the positive electrode mixture layer PEFH having a high porosity and the positive electrode mixture layer PEFL having a low porosity are alternately formed in the winding direction. In the negative electrode NEL, the negative electrode mixture layer having a high porosity. NEFH and a negative electrode mixture layer NEFL having a low porosity are alternately formed in the winding direction.
　また、電極捲回体ＷＲＦの第１例では、集電箔ＰＥＰの搬送方向に沿って形成された空隙率の低い正極合剤層ＰＥＦＬが正極集電タブＰＴＡＢ側に位置するように捲回され、集電箔ＮＥＰの搬送方向に沿って形成された空隙率の低い負極合剤層ＮＥＦＬが正極集電タブＰＴＡＢ側に位置するように捲回されている。従って、電極捲回体ＷＲＦの第１例は、缶底側から缶蓋方向に向かって空隙率の高い正極合剤層ＰＥＦＨが形成された正極ＰＥＬと、缶底側から缶蓋方向に向かって空隙率の高い負極合剤層ＮＥＦＨが形成された負極ＮＥＬとを有する。 In the first example of the electrode winding body WRF, the positive electrode mixture layer PEFL having a low porosity formed along the conveying direction of the current collector foil PEP is wound so as to be positioned on the positive electrode current collector tab PTAB side. The negative electrode mixture layer NEFL having a low porosity formed along the conveying direction of the current collector foil NEP is wound so as to be positioned on the positive electrode current collector tab PTAB side. Accordingly, the first example of the electrode winding body WRF includes the positive electrode PEL on which the positive electrode mixture layer PEFH having a high porosity is formed from the can bottom side toward the can lid direction, and the can bottom side toward the can lid direction. A negative electrode mixture layer NEFH having a high porosity.
　また、図３（ｂ）に示すように、電極捲回体ＷＲＦの第２例は、電極捲回体ＷＲＦの第１例と同様に、軸心ＣＲの回りに捲回された正極ＰＥＬ、セパレータＳＰ１，ＳＰ２および負極ＮＥＬから構成される。そして、正極ＰＥＬでは、空隙率の高い正極合剤層ＰＥＦＨと空隙率の低い正極合剤層ＰＥＦＬとが捲回方向に交互に形成されており、負極ＮＥＬでは、空隙率の高い負極合剤層ＮＥＦＨと空隙率の低い負極合剤層ＮＥＦＬとが捲回方向に交互に形成されている。 Further, as shown in FIG. 3B, the second example of the electrode winding body WRF is similar to the first example of the electrode winding body WRF, the positive electrode PEL wound around the axis CR, the separator SP1 and SP2 and negative electrode NEL are comprised. In the positive electrode PEL, the positive electrode mixture layer PEFH having a high porosity and the positive electrode mixture layer PEFL having a low porosity are alternately formed in the winding direction. In the negative electrode NEL, the negative electrode mixture layer having a high porosity. NEFH and a negative electrode mixture layer NEFL having a low porosity are alternately formed in the winding direction.
　しかし、電極捲回体ＷＲＦの第２例では、電極捲回体ＷＲＦの第１例と異なり、集電箔ＰＥＰの搬送方向に沿って形成された空隙率の低い正極合剤層ＰＥＦＬが負極集電タブＮＴＡＢ側に位置するように捲回され、集電箔ＮＥＰの搬送方向に沿って形成された空隙率の低い負極合剤層ＮＥＦＬが負極集電タブＮＴＡＢ側に位置するように捲回されている。従って、電極捲回体ＷＲＦの第２例は、缶蓋側から缶底方向に向かって空隙率の高い正極合剤層ＰＥＦＨが形成された正極ＰＥＬと、缶蓋側から缶底方向に向かって空隙率の高い負極合剤層ＮＥＦＨが形成された負極ＮＥＬとを有する。 However, in the second example of the electrode winding body WRF, unlike the first example of the electrode winding body WRF, the positive electrode mixture layer PEFL having a low porosity formed along the conveying direction of the current collector foil PEP is formed as the negative electrode collector. The negative electrode mixture layer NEFL having a low porosity formed along the conveying direction of the current collector foil NEP is wound so as to be positioned on the negative electrode current collector tab NTAB side. ing. Therefore, the second example of the electrode winding body WRF includes the positive electrode PEL on which the positive electrode mixture layer PEFH having a high porosity is formed from the can lid side toward the can bottom direction, and the can lid side toward the can bottom direction. A negative electrode mixture layer NEFH having a high porosity.
　（電極および電極捲回体の製造方法の変形例）
　次に、本実施例１の変形例による電極および電極捲回体の製造方法について、以下に説明する。 (Variation of manufacturing method of electrode and electrode winding body)
Next, the manufacturing method of the electrode and electrode winding body by the modification of a present Example 1 is demonstrated below.
　（１）まず、前述した塗工工程と同様にして、集電箔ＰＥＰの表面上に正極合剤層ＰＥＦを形成し、集電箔ＮＥＰの表面上に負極合剤層ＮＥＦを形成する。 (1) First, the positive electrode mixture layer PEF is formed on the surface of the current collector foil PEP, and the negative electrode mixture layer NEF is formed on the surface of the current collector foil NEP, in the same manner as the coating step described above.
　（２）次に、乾燥工程について、図４（ａ）、（ｂ）および（ｃ）を用いて説明する。ここでは、正極の製造方法について説明するが、負極の製造方法もほぼ同様である。図４（ａ）、（ｂ）および（ｃ）はそれぞれ、本実施例１の変形例によるスラリー塗布後の乾燥工程で用いる乾燥用金属部材、乾燥中の正極合剤層および乾燥後の正極合剤層を示す模式図である。 (2) Next, a drying process is demonstrated using FIG. 4 (a), (b) and (c). Here, the manufacturing method of the positive electrode will be described, but the manufacturing method of the negative electrode is substantially the same. 4 (a), (b) and (c) respectively show the metal member for drying used in the drying step after slurry application according to the modified example of Example 1, the positive electrode mixture layer during drying, and the positive electrode mixture after drying. It is a schematic diagram which shows an agent layer.
　まず、図４（ａ）に示す、乾燥用金属部材ＭＤ２を準備する。乾燥用金属部材ＭＤ２は、第１方向に第２ピッチＰ２を有して配置された複数の金属線ＭＷからなる。複数の金属線ＭＷの一方の端部および他方の端部はそれぞれ支持部材によって繋がっており、複数の金属線ＭＷは固定されている。複数の金属線ＭＷの線幅は、例えば０．１～１．０ｍｍであり、複数の金属線ＭＷの第１方向の第２ピッチＰ２は、例えば１０ｍｍである。複数の金属線ＭＷは、例えばステンレス、鉄（Ｆｅ）、金（Ａｕ）、銀（Ａｇ）、鉄（Ｆｅ）合金またはニッケル（Ｎｉ）合金などからなる。金属線ＭＷの第１方向に沿った断面は略円形状であるが、これに限定されるものではなく、例えば略四角形状であってもよい。 First, a drying metal member MD2 shown in FIG. 4 (a) is prepared. The drying metal member MD2 is composed of a plurality of metal lines MW arranged with a second pitch P2 in the first direction. One end and the other end of the plurality of metal wires MW are connected by a support member, and the plurality of metal wires MW are fixed. The line width of the plurality of metal lines MW is, for example, 0.1 to 1.0 mm, and the second pitch P2 in the first direction of the plurality of metal lines MW is, for example, 10 mm. The plurality of metal wires MW are made of, for example, stainless steel, iron (Fe), gold (Au), silver (Ag), iron (Fe) alloy, nickel (Ni) alloy, or the like. The cross section along the first direction of the metal line MW is substantially circular, but is not limited thereto, and may be, for example, a substantially square shape.
　次に、図４（ｂ）に示すように、その表面上に正極合剤層ＰＥＦが塗布された集電箔ＰＥＰを、乾燥用金属部材ＭＤ２上に搭載する。この際、集電箔ＰＥＰは、乾燥用金属部材ＭＤ２の複数の金属線ＭＷ上に搭載される。その後、乾燥用金属部材ＭＤ２上に搭載された集電箔ＰＥＰを、例えば１２０℃の熱風乾燥炉内に搬送して、集電箔ＰＥＰの表面上に塗布された、スラリー塗布後の正極合剤層ＰＥＦを乾燥させる。ここで、上記第１方向と集電箔ＰＥＰの搬送方向とは一致する。集電箔ＰＥＰの搬送速度は、例えば５～１００ｍ／分である。量産製造時には、乾燥用金属部材ＭＤ２を集電箔ＰＥＰと共に熱風乾燥炉中を一定速度で搬送することにより、生産性を維持することができる。 Next, as shown in FIG. 4B, the current collector foil PEP having the positive electrode mixture layer PEF applied on the surface thereof is mounted on the drying metal member MD2. At this time, the current collector foil PEP is mounted on the plurality of metal wires MW of the drying metal member MD2. Thereafter, the current collector foil PEP mounted on the drying metal member MD2 is conveyed into, for example, a 120 ° C. hot-air drying furnace, and applied to the surface of the current collector foil PEP. The layer PEF is dried. Here, the said 1st direction and the conveyance direction of current collection foil PEP correspond. The conveying speed of the current collector foil PEP is, for example, 5 to 100 m / min. At the time of mass production, productivity can be maintained by conveying the drying metal member MD2 together with the current collector foil PEP in the hot air drying furnace at a constant speed.
　上記乾燥工程を経ることにより、図４（ｃ）に示すように、乾燥用金属部材ＭＤ２の複数の金属線ＭＷ上に位置しなかった正極合剤層ＰＥＦＨの空隙率が、乾燥用金属部材ＭＤ２の複数の金属線ＭＷ上に位置した正極合剤層ＰＥＦＬの空隙率よりも高くなる。これにより、例えば幅５ｍｍの空隙率の低い正極合剤層ＰＥＦＬと幅５ｍｍの空隙率の高い正極合剤層ＰＥＦＨとが、交互に集電箔ＰＥＰの搬送方向に形成される。その後、乾燥した正極合剤層ＰＥＦをプレス圧縮することにより、正極が製造される。負極も同様に製造することができる。 By passing through the drying step, as shown in FIG. 4C, the porosity of the positive electrode mixture layer PEFH that is not located on the plurality of metal wires MW of the drying metal member MD2 is reduced to the drying metal member MD2. It becomes higher than the porosity of the positive electrode mixture layer PEFL located on the plurality of metal wires MW. Thereby, for example, a positive electrode mixture layer PEFL with a width of 5 mm and a low porosity and a positive electrode mixture layer PEFH with a width of 5 mm and a high porosity are alternately formed in the conveying direction of the current collector foil PEP. Then, a positive electrode is manufactured by press-compressing the dried positive electrode mixture layer PEF. The negative electrode can be produced in the same manner.
　（３）次に、捲回工程について、図５を用いて説明する。図５は、本実施例１の変形例による互いに空隙率が異なる２つの電極合剤層が捲回方向に交互に形成された電極を有する電極捲回体の第３例の模式図である。 (3) Next, the winding process will be described with reference to FIG. FIG. 5 is a schematic diagram of a third example of an electrode winding body having electrodes in which two electrode mixture layers having different porosity are alternately formed in the winding direction according to a modification of the first embodiment.
　図５に示すように、電極捲回体ＷＲＦの第３例は、軸心ＣＲの回りに捲回された正極ＰＥＬ、セパレータＳＰ１，ＳＰ２および負極ＮＥＬから構成される。そして、正極ＰＥＬでは、空隙率の高い正極合剤層ＰＥＦＨと空隙率の低い正極合剤層ＰＥＦＬとが捲回方向に交互に形成されており、負極ＮＥＬでは、空隙率の高い負極合剤層ＮＥＦＨと空隙率の低い負極合剤層ＮＥＦＬとが捲回方向に交互に形成されている。 As shown in FIG. 5, the third example of the electrode winding body WRF includes a positive electrode PEL wound around the axis CR, separators SP1 and SP2, and a negative electrode NEL. In the positive electrode PEL, the positive electrode mixture layer PEFH having a high porosity and the positive electrode mixture layer PEFL having a low porosity are alternately formed in the winding direction. In the negative electrode NEL, the negative electrode mixture layer having a high porosity. NEFH and a negative electrode mixture layer NEFL having a low porosity are alternately formed in the winding direction.
　また、電極捲回体ＷＲＦの第３例では、缶蓋－缶底方向に、捲回方向に沿った集電箔ＰＥＰの一方の辺から捲回方向に沿った集電箔ＰＥＰの他方の辺に達する空隙率の高い正極合剤層ＰＥＦＨが形成された正極ＰＥＬを有する。さらに、電極捲回体ＷＲＦの第３例では、缶蓋－缶底方向に、捲回方向に沿った集電箔ＮＥＰの一方の辺から捲回方向に沿った集電箔ＮＥＰの他方の辺に達する空隙率の高い負極合剤層ＮＥＦＨが形成された負極ＮＥＬを有する。 In the third example of the electrode winding body WRF, the other side of the current collector foil PEP along the winding direction extends from one side of the current collector foil PEP along the winding direction in the direction of the can lid-can bottom. A positive electrode PEL on which a positive electrode mixture layer PEFH having a high porosity reaching 1 is formed. Further, in the third example of the electrode winding body WRF, the other side of the current collector foil NEP along the winding direction from one side of the current collector foil NEP along the winding direction in the direction of the can lid-can bottom. The negative electrode NEL in which the negative electrode mixture layer NEFH having a high porosity reaching the upper limit is formed.
　（電極の構造）
　次に、本実施例１による電極の構造について、図６および図７を用いて以下に説明する。図６は、本実施例１による空隙率の低い電極合剤層と空隙率の高い電極合剤層とが交互に形成された電極の断面（集電箔の搬送方向に沿った方向の断面）の一部を拡大して示す模式図である。図７は、空隙率の低い電極合剤層の空隙率、および空隙率の高い電極合剤層の空隙率を示すグラフ図である。なお、空隙率の低い電極合剤層は、乾燥工程において金属線近傍となる箇所（例えば金属線から２．５ｍｍよりも近い領域）であり、空隙率の高い電極合剤層は、乾燥工程において金属線近傍とならない箇所（例えば金属線から２．５ｍｍ以上離れた遠い領域）である。 (Electrode structure)
Next, the structure of the electrode according to Example 1 will be described below with reference to FIGS. FIG. 6 is a cross section of an electrode in which an electrode mixture layer having a low porosity and an electrode mixture layer having a high porosity are alternately formed according to Example 1 (cross section in the direction along the conveying direction of the current collector foil). It is a schematic diagram which expands and shows a part of. FIG. 7 is a graph showing the porosity of an electrode mixture layer having a low porosity and the porosity of an electrode mixture layer having a high porosity. In addition, an electrode mixture layer with a low porosity is a location (for example, a region closer to 2.5 mm from the metal wire) near the metal wire in the drying process, and an electrode mixture layer with a high porosity is used in the drying process. It is a portion that is not near the metal line (for example, a far region away from the metal wire by 2.5 mm or more).
　図６に示すように、電極ＥＬは、集電体（集電箔）ＥＰと、集電体ＥＰ上に形成された電極合剤層ＥＦとからなり、電極合剤層ＥＦは、活物質ＡＳ、導電助剤ＣＡおよび結着材（バインダ）ＢＤを含有する。活物質ＡＳの平均粒径は、例えば２～１０μｍであり、空隙率の低い電極合剤層の粒度分布と空隙率の高い電極合剤層の粒度分布とは同一である。ここで、「同一」とは、完全同一という意味ではなく、実質同一またはほぼ同一という意味であって、ばらつきを考慮した一定の範囲を含む。例えば上記したように、活物質ＡＳの平均粒径においても、２～１０μｍのばらつきを有している。 As shown in FIG. 6, the electrode EL includes a current collector (current collector foil) EP and an electrode mixture layer EF formed on the current collector EP. The electrode mixture layer EF includes the active material AS. , Containing conductive aid CA and binder (binder) BD. The average particle size of the active material AS is, for example, 2 to 10 μm, and the particle size distribution of the electrode mixture layer having a low porosity and the particle size distribution of the electrode mixture layer having a high porosity are the same. Here, “same” does not mean completely the same, but means substantially the same or substantially the same, and includes a certain range in consideration of variations. For example, as described above, the average particle diameter of the active material AS also has a variation of 2 to 10 μm.
　空隙率の定量評価は、例えば電極合剤層ＥＦの断面ＳＥＭ（Scanning Electron Microscope）観察により行うことができる。ＳＥＭ像から、電極合剤層ＥＦの断面の空隙面積および固形分面積を求め、式（１）により空隙率を算出した。 Quantitative evaluation of the porosity can be performed, for example, by observing a cross section SEM (Scanning Electron Microscope) of the electrode mixture layer EF. From the SEM image, the void area and the solid content area of the cross section of the electrode mixture layer EF were obtained, and the void ratio was calculated by the formula (1).
　空隙率（面積％）＝
　　　　　空隙面積／（空隙面積＋固形分面積）×１００　　　　　式（1） Porosity (area%) =
Void area / (Cavity area + Solid content area) × 100 Formula (1)
　断面ＳＥＭ観察では、奥行き方向の空隙率の定量評価は困難であるが、観察面近傍では電極の構造は同様であると考えられる。そこで、本実験では、空隙率（面積％）≒空隙率（体積％）として評価した。空隙率の低い電極合剤層の断面と空隙率の高い電極合剤層の断面をそれぞれ３箇所観察し、空隙率を算出した。 In cross-sectional SEM observation, it is difficult to quantitatively evaluate the porosity in the depth direction, but the electrode structure is considered to be similar in the vicinity of the observation surface. Therefore, in this experiment, evaluation was performed as porosity (area%) ≈porosity (volume%). The cross section of the electrode mixture layer having a low porosity and the cross section of the electrode mixture layer having a high porosity were each observed at three locations, and the porosity was calculated.
　図７に、空隙率の低い電極合剤層の空隙率、および空隙率の高い電極合剤層の空隙率を示す。図７に示した空隙率は３箇所の平均値であり、エラーバーで最大値と最小値を示している。空隙率の低い電極合剤層の空隙率は１８～２８体積％程度、空隙率の高い電極合剤層の空隙率は３９～４３体積％程度となり、空隙率の差は約１１～２５体積％であった。 FIG. 7 shows the porosity of the electrode mixture layer having a low porosity and the porosity of the electrode mixture layer having a high porosity. The porosity shown in FIG. 7 is an average value at three locations, and the error bar indicates the maximum value and the minimum value. The porosity of the electrode mixture layer with low porosity is about 18 to 28% by volume, the porosity of the electrode mixture layer with high porosity is about 39 to 43% by volume, and the difference in porosity is about 11 to 25% by volume. Met.
　このように、空隙率の低い電極合剤層と空隙率の高い電極合剤層とが得られた原因は以下のように考えられる。 As described above, the reason why the electrode mixture layer having a low porosity and the electrode mixture layer having a high porosity are obtained is considered as follows.
　乾燥工程において、金属線近傍の電極合剤層は、金属線近傍ではない電極合剤層に比べて温度上昇が早く、電極スラリー（スラリー状の電極材料）に含まれるＮＭＰの揮発速度が速いと考えられる。そのため、金属線近傍の電極合剤層ではＮＭＰが揮発して無くなり、金属線近傍ではない箇所ではＮＭＰが揮発せずに残存する状態が発生する。このような状態が発生すると、ＮＭＰが残存している箇所からＮＭＰが揮発して無くなった箇所に向かってＮＭＰが流動する。このとき、ＮＭＰの流動に伴い活物質などの固形分も同時に移動するため、金属線近傍の電極合剤層では固形分の密度が高くなり、金属線近傍ではない電極合剤層では固形分の密度が低くなると考えられる。固形分の密度が異なるため、空隙率の異なる電極合剤層を形成することができる。 In the drying process, the electrode mixture layer near the metal wire has a faster temperature rise than the electrode mixture layer not near the metal wire, and the volatilization rate of NMP contained in the electrode slurry (slurry electrode material) is high. Conceivable. Therefore, NMP volatilizes and disappears in the electrode mixture layer in the vicinity of the metal wire, and NMP does not volatilize in a portion that is not in the vicinity of the metal wire. When such a state occurs, the NMP flows from the location where the NMP remains to the location where the NMP has evaporated and disappeared. At this time, the solid content of the active material moves simultaneously with the flow of NMP, so the density of the solid content increases in the electrode mixture layer near the metal wire, and the solid content in the electrode mixture layer not near the metal wire. It is thought that the density is lowered. Since the solid contents have different densities, electrode mixture layers having different porosity can be formed.
　また、空隙率が互いに異なる２以上の電極合剤層を得るためには、上記メカニズムの通り、乾燥工程における電極合剤層に温度分布を設ければよく、乾燥工程における乾燥用金属部材の金属線の形状を制御することにより、空隙率が互いに異なる２以上の電極合剤層を任意のパターンで作製することができる。例えば図８（ａ）に示すように、空隙率の高い正極合剤層ＰＥＦＨの形状を平行四辺形とすることもでき、または、図８（ｂ）に示すように、空隙率の高い正極合剤層ＰＥＦＨの形状を波形とすることもできる。 Further, in order to obtain two or more electrode mixture layers having different porosity, it is only necessary to provide a temperature distribution in the electrode mixture layer in the drying step as described above, and the metal of the metal member for drying in the drying step By controlling the shape of the line, two or more electrode mixture layers having different porosity can be produced in an arbitrary pattern. For example, as shown in FIG. 8 (a), the shape of the positive electrode mixture layer PEFH having a high porosity can be a parallelogram, or as shown in FIG. 8 (b), the positive electrode mixture having a high porosity can be used. The shape of the agent layer PEFH can also be corrugated.
　（リチウムイオン電池の諸特性）
　次に、本実施例１によるリチウムイオン電池において、生産性の観点から電解液の浸透速度、および電池特性の観点から電池の内部抵抗（直流抵抗）を評価した結果について、図９および図１０を用いて以下に説明する。図９は、本実施例１による電極および比較例による電極における電解液の浸透速度を示すグラフ図である。図１０は、本実施例１による電極を備える電池および比較例による電極を備える電池における内部抵抗を示すグラフ図である。 (Various characteristics of lithium-ion battery)
Next, in the lithium ion battery according to Example 1, the results of evaluating the penetration rate of the electrolytic solution from the viewpoint of productivity and the internal resistance (DC resistance) of the battery from the viewpoint of battery characteristics are shown in FIGS. This will be described below. FIG. 9 is a graph showing the permeation rate of the electrolytic solution in the electrode according to the first embodiment and the electrode according to the comparative example. FIG. 10 is a graph showing the internal resistance in the battery including the electrode according to the first embodiment and the battery including the electrode according to the comparative example.
　電解液の浸透速度および電池の内部抵抗の評価を行った本実施例１による電極には、例えば図４（ｃ）に示した、５ｍｍ毎に空隙率の低い電極合剤層と空隙率の高い電極合剤層とが交互に形成された電極を用いた。また、本実施例１による電極では、空隙率の低い電極合剤層の活物質密度は約２．８ｇ／ｃｍ３、空隙率の高い電極合剤層の活物質密度は約２．１ｇ／ｃｍ３であり、空隙率の低い電極合剤層と空隙率の高い電極合剤層との面積比は１：１である。 For the electrode according to Example 1 that evaluated the penetration rate of the electrolytic solution and the internal resistance of the battery, for example, an electrode mixture layer having a low porosity and a high porosity every 5 mm shown in FIG. An electrode in which electrode mixture layers were alternately formed was used. In the electrode according to Example 1, the active material density of the electrode mixture layer having a low porosity is about 2.8 g / cm 3 , and the active material density of the electrode mixture layer having a high porosity is about 2.1 g / cm 3. 3. The area ratio of the electrode mixture layer having a low porosity and the electrode mixture layer having a high porosity is 1: 1.
　また、電解液の浸透速度および電池の内部抵抗の評価を行った比較例による電極には、集電箔の表面上に電極スラリーを均一密度で塗布した電極合剤層を、例えば１２０℃の熱風乾燥炉で乾燥させ、空隙率が一様な電極を作製した。比較例による電極では、電極合剤層の活物質密度は約２．７ｇ／ｃｍ３である。 Further, for the electrode according to the comparative example in which the penetration rate of the electrolytic solution and the internal resistance of the battery were evaluated, an electrode mixture layer in which the electrode slurry was applied at a uniform density on the surface of the current collector foil, for example, hot air at 120 ° C. It dried with the drying furnace and produced the electrode with the uniform porosity. In the electrode according to the comparative example, the active material density of the electrode mixture layer is about 2.7 g / cm 3 .
　まず、電解液の浸透速度の評価方法および実験結果について説明する。 First, the method for evaluating the penetration rate of the electrolyte and the experimental results will be described.
　電極合剤層の表面に電解液を５μｌ滴下すると、電解液は電極合剤層中を浸透すると共に電極合剤層の表面を広がる。電解液の広がりが最大となった後は、電極合剤層に電解液が浸透する様子が観察される。電極合剤層に電解液が浸透して電解液が見えなくなった時刻を浸透終了時刻と定義し、電解液が広がった面積と電極合剤層の厚みとの積を浸透体積と定義した。浸透時間（電解液滴下直後から浸透終了までの時間）を測定し、式（２）により浸透速度を算出した。 When 5 μl of the electrolytic solution is dropped on the surface of the electrode mixture layer, the electrolytic solution penetrates through the electrode mixture layer and spreads over the surface of the electrode mixture layer. After the spread of the electrolytic solution is maximized, it is observed that the electrolytic solution penetrates into the electrode mixture layer. The time when the electrolyte solution permeated into the electrode mixture layer and the electrolyte solution was not visible was defined as the penetration end time, and the product of the area where the electrolyte solution spread and the thickness of the electrode mixture layer was defined as the penetration volume. The permeation time (time from immediately after the electrolytic droplet was dropped to the end of permeation) was measured, and the permeation rate was calculated by equation (2).
　浸透速度（μｌ／（ｓ・ｃｍ３））＝
　　　　　滴下電解液量／（浸透体積×浸透時間）　　　　　　　式（２） Permeation rate (μl / (s · cm 3 )) =
Amount of dropped electrolyte / (infiltration volume × infiltration time) Formula (2)
　図９に、本実施例１による電極と、比較例による電極とにおける電解液の浸透速度を示す。図９では、比較例による電極の浸透速度を１とし、相対値で浸透速度を示した。比較例による電極と比較して、本実施例１による電極では、浸透速度が１．２倍に向上することを確認した。 FIG. 9 shows the permeation rate of the electrolytic solution in the electrode according to Example 1 and the electrode according to the comparative example. In FIG. 9, the permeation rate of the electrode according to the comparative example is 1, and the permeation rate is shown as a relative value. Compared with the electrode according to the comparative example, it was confirmed that the penetration rate was improved by 1.2 times in the electrode according to the present Example 1.
　図３（ａ）に示したような、空隙率の高い電極合剤層を缶底側から缶蓋方向に向かって形成する場合は、缶底側から電解液を注液することで、注液時間を短縮することができる。一方、図３（ｂ）に示したような、空隙率の高い電極合剤層を缶蓋側から缶底方向に向かって形成する場合は、缶蓋側から電解液を注液することで、注液時間を短縮することができる。注液速度向上の観点からは、缶底側から缶蓋方向または缶蓋側から缶底方向に向かって形成する空隙率の高い合剤層の長さ（Ｌ）は、缶蓋－缶底方向の電極合剤層の幅（Ｗ）の２／３倍以上、かつ、１倍以下（２Ｗ／３＜Ｌ≦Ｗ）とすることが好ましい（図３（ａ）参照）。缶底側から缶蓋方向または缶蓋側から缶底方向に向かって形成する空隙率の高い電極合剤層の長さ（Ｌ）が、缶蓋－缶底方向の電極合剤層の幅（Ｗ）の２／３倍未満となると、電解液が浸透しやすい電極合剤層が短くなり、注液時間を短縮する効果が低くなるからである。 When an electrode mixture layer having a high porosity as shown in FIG. 3A is formed from the can bottom side toward the can lid direction, the electrolyte solution is injected from the can bottom side. Time can be shortened. On the other hand, when forming an electrode mixture layer with a high porosity as shown in FIG. 3 (b) from the can lid side toward the can bottom, by injecting an electrolyte from the can lid side, Injection time can be shortened. From the viewpoint of improving the injection speed, the length (L) of the mixture layer having a high porosity formed from the bottom of the can to the can lid or from the can lid to the bottom of the can is determined from the direction of the can lid to the bottom of the can. The width (W) of the electrode mixture layer is preferably 2/3 or more and 1 or less (2W / 3 <L ≦ W) (see FIG. 3A). The length (L) of the electrode mixture layer having a high porosity formed from the can bottom side toward the can lid direction or from the can lid side toward the can bottom direction is the width of the electrode mixture layer in the can lid-can bottom direction ( If the ratio is less than 2/3 times W), the electrode mixture layer in which the electrolyte solution easily penetrates becomes short, and the effect of shortening the injection time becomes low.
　また、注液時間を短縮する効果が最も高くなることから、空隙率の高い電極合剤層の長さ（Ｌ）を、缶蓋－缶底方向の電極合剤層の幅（Ｗ）と等しく（Ｌ＝Ｗ）することがさらに好ましい（図５参照）。この場合には、缶底側と缶蓋側のどちらから電解液を注液しても、注液時間を短縮することができる。 In addition, since the effect of shortening the injection time is the highest, the length (L) of the electrode mixture layer having a high porosity is equal to the width (W) of the electrode mixture layer in the can lid-can bottom direction. More preferably (L = W) (see FIG. 5). In this case, the injection time can be shortened by injecting the electrolyte from either the can bottom side or the can lid side.
　次に、電池の内部抵抗の評価方法および実験結果について説明する。 Next, the battery internal resistance evaluation method and experimental results will be described.
　本実施例１および比較例ともに、リチウムマンガンコバルトニッケル複合酸化物、導電助剤（黒鉛粉末）および結着材（ポリフッ化ビニリデン）からなる正極と、炭素粉末、導電助剤（グラファイト）および結着材（ポリフッ化ビニリデン）からなる負極を用いた。さらに、本実施例１および比較例ともに、厚さ２０μｍの多孔質ポリプロピレンからなるセパレータと、有機溶媒（炭酸エチル、炭酸ジメチルまたは炭酸エチルメチル）、電解塩（ヘキサフルオロリン酸リチウム）からなる電解液を用いて、リチウムイオン電池を作製した。作製したリチウムイオン電池を電池電圧４．２Ｖまで１Ｃで定電流充電した後、定電圧充電を行い、満充電の状態にした。満充電の状態から、Ｃレート：０．２～２０．０Ｃの各電流値で放電させ、１０秒後の電池電圧を測定し、放電電流に対する電池電圧の傾きを電池の内部抵抗として算出した。Ｃレートとは、電池容量を１時間で放電する電流値を基準にした電流値の表現である。例えば１時間かけて放電するときの電流値は１Ｃ、０．５時間かけて放電するときの電流値は２Ｃとなる。内部抵抗が低い程、放電時の電池電圧の低下が小さいため、高出力で放電することができることを意味する。 In both Example 1 and Comparative Example, a positive electrode composed of a lithium manganese cobalt nickel composite oxide, a conductive additive (graphite powder) and a binder (polyvinylidene fluoride), a carbon powder, a conductive additive (graphite), and a binder A negative electrode made of a material (polyvinylidene fluoride) was used. Further, in both Example 1 and Comparative Example, an electrolytic solution comprising a separator made of porous polypropylene having a thickness of 20 μm, an organic solvent (ethyl carbonate, dimethyl carbonate or ethyl methyl carbonate), and an electrolytic salt (lithium hexafluorophosphate). A lithium ion battery was prepared using The prepared lithium ion battery was charged with a constant current at 1 C up to a battery voltage of 4.2 V, and then charged with a constant voltage to obtain a fully charged state. From a fully charged state, the battery was discharged at each current value of C rate: 0.2 to 20.0 C, the battery voltage after 10 seconds was measured, and the slope of the battery voltage with respect to the discharge current was calculated as the internal resistance of the battery. The C rate is an expression of a current value based on a current value for discharging the battery capacity in one hour. For example, the current value when discharging over 1 hour is 1C, and the current value when discharging over 0.5 hour is 2C. The lower the internal resistance, the lower the battery voltage during discharge, which means that the battery can be discharged at a higher output.
　図１０に、本実施例１による電極を用いた電池と、比較例による電極を用いた電池における内部抵抗を示す。図１０では、比較例による電極を用いた電池の内部抵抗を１とし、相対値で内部抵抗を示した。比較例による電極を用いた電池と比較して、実施例１による電極を用いた電池では、内部抵抗が約５％低減できることを確認した。 FIG. 10 shows the internal resistance of the battery using the electrode according to Example 1 and the battery using the electrode according to the comparative example. In FIG. 10, the internal resistance of the battery using the electrode according to the comparative example is 1, and the internal resistance is shown as a relative value. It was confirmed that the internal resistance can be reduced by about 5% in the battery using the electrode according to Example 1 as compared with the battery using the electrode according to the comparative example.
　このように、本実施例１によれば、電解液の浸透時間を短縮することができる。さらに、リチウムイオン電池の充放電時の内部抵抗を低減することができる。これらにより、リチウムイオン電池の生産性の向上と電池特性の向上との両立を図ることができる。 Thus, according to the first embodiment, the permeation time of the electrolytic solution can be shortened. Furthermore, the internal resistance during charging / discharging of the lithium ion battery can be reduced. As a result, it is possible to improve both the productivity of the lithium ion battery and the battery characteristics.
　次に、本実施例１と、前記特許文献１および前記特許文献２との違いを以下に説明する。 Next, differences between the first embodiment and Patent Document 1 and Patent Document 2 will be described below.
　前記特許文献１には、電極塗工方向に沿って複数の空隙率の高い電極合剤層を形成する方法が記載されている。この場合、電極を捲回すると、電極捲回体の缶蓋－缶底方向に空隙率の高い電極合剤層が形成されないため、電解液の浸透速度を早くする効果は小さい。一方、本実施例１では、集電箔の搬送方向と集電箔の表面で交差する方向に空隙率の高い電極合剤層を形成しているので、電極を捲回すると、図３（ａ）および（ｂ）並びに図５に示すように、電極捲回体の缶蓋－缶底方向に空隙率の高い電極合剤層が形成される。従って、電解液の注液時には、空隙率の高い電極合剤層を通って缶底側から缶蓋側へ、または缶蓋側から缶底側へ電解液が浸透していくため、注液時間を短縮でき、前記特許文献１よりも生産性を向上させることができる。本実施例１と前記特許文献１との缶蓋－缶底方向の浸透速度の違いは、図９に示す結果に相当する。 Patent Document 1 describes a method of forming a plurality of electrode mixture layers having a high porosity along the electrode coating direction. In this case, when the electrode is wound, an electrode mixture layer having a high porosity is not formed in the direction of the can lid-can bottom of the electrode wound body, so that the effect of increasing the permeation rate of the electrolytic solution is small. On the other hand, in Example 1, since the electrode mixture layer having a high porosity is formed in a direction intersecting with the conveying direction of the current collector foil and the surface of the current collector foil, when the electrode is wound, FIG. ) And (b) and as shown in FIG. 5, an electrode mixture layer having a high porosity is formed in the direction of the can lid-can bottom of the electrode winding body. Therefore, at the time of injecting the electrolyte solution, the electrolyte solution penetrates from the bottom of the can to the can lid side or from the can lid side to the can bottom side through the electrode mixture layer having a high porosity. Can be shortened, and productivity can be improved as compared with Patent Document 1. The difference in the permeation speed in the can lid-can bottom direction between Example 1 and Patent Document 1 corresponds to the result shown in FIG.
　前記特許文献２には、微粉末を除去した活物質を用いて空隙サイズの大きい電極合剤層を形成した後、微粉末を除去していない活物質を用いて空隙サイズの小さい電極合剤層を形成する方法が記載されている。前記特許文献２では、缶蓋－缶底方向に空隙サイズの大きい電極合剤層を形成することができるため、電解液の浸透時間を短縮することは可能である。しかし、活物質から微粉末を除去する工程が必要となることに加え、電極合剤を塗布する工程が２回必要となるため、電極の製造工程数が増加する。一方、本実施例１では、乾燥工程において、乾燥用金属部材上に、その表面に電極合剤層が形成された集電箔を配置するのみであるので、電極の製造工程数の観点で、前記特許文献２よりも生産性の向上に有利であるといえる。 In Patent Document 2, an electrode mixture layer having a large void size is formed using an active material from which fine powder has been removed, and then an electrode mixture layer having a small void size using an active material from which fine powder has not been removed. A method of forming is described. In Patent Document 2, since an electrode mixture layer having a large gap size can be formed in the direction of the can lid-can bottom, it is possible to reduce the permeation time of the electrolytic solution. However, in addition to requiring a step of removing fine powder from the active material, the step of applying the electrode mixture is required twice, which increases the number of electrode manufacturing steps. On the other hand, in the present Example 1, in the drying process, since only the current collector foil having the electrode mixture layer formed on the surface thereof is disposed on the metal member for drying, in terms of the number of manufacturing steps of the electrode, It can be said that it is more advantageous for improving the productivity than Patent Document 2.
　また、前記特許文献２では、微粉末の活物質を除去する必要がある。微粉末は、活物質中のリチウムイオンの拡散距離が短く、また、活物質重量あたりの反応面積が大きいという特徴を持つ。そのため、微粉末の除去は内部抵抗の低減に不利である。一方、本実施例１では、空隙率の高い電極合剤層と空隙率の低い電極合剤層において、粒度分布が同一の活物質材料を使用している。従って、空隙率の低い電極合剤層にも微粉末が存在しているため、前記特許文献２よりも内部抵抗の低減効果が得られて、入出力特性を向上させることができる。 In Patent Document 2, it is necessary to remove the active material in the form of fine powder. The fine powder is characterized by a short diffusion distance of lithium ions in the active material and a large reaction area per weight of the active material. Therefore, removal of fine powder is disadvantageous for reducing internal resistance. On the other hand, in Example 1, active material materials having the same particle size distribution are used in the electrode mixture layer having a high porosity and the electrode mixture layer having a low porosity. Therefore, since fine powder is also present in the electrode mixture layer having a low porosity, an effect of reducing internal resistance can be obtained as compared with Patent Document 2, and input / output characteristics can be improved.
　本実施例２による電極および電極捲回体の製造方法について、以下に説明する。 A method for manufacturing the electrode and the electrode winding body according to the second embodiment will be described below.
　（１）まず、前述した実施例１による塗工工程と同様にして、集電箔ＰＥＰの表面上に正極合剤層ＰＥＦを形成し、集電箔ＮＥＰの表面上に負極合剤層ＮＥＦを形成する。 (1) First, the positive electrode mixture layer PEF is formed on the surface of the current collector foil PEP, and the negative electrode mixture layer NEF is formed on the surface of the current collector foil NEP in the same manner as in the coating step according to Example 1 described above. Form.
　（２）次に、乾燥工程について、図１１（ａ）、（ｂ）および（ｃ）を用いて説明する。ここでは、正極の製造方法について説明するが、負極の製造方法もほぼ同様である。図１１（ａ）、（ｂ）および（ｃ）はそれぞれ、本実施例２によるスラリー塗布後の乾燥工程で用いる乾燥用金属部材、乾燥中の正極合剤層および乾燥後の正極合剤層を示す模式図である。 (2) Next, a drying process is demonstrated using FIG. 11 (a), (b) and (c). Here, the manufacturing method of the positive electrode will be described, but the manufacturing method of the negative electrode is substantially the same. 11 (a), (b) and (c) respectively show a drying metal member, a positive electrode mixture layer being dried, and a positive electrode mixture layer after being dried used in the drying step after slurry application according to the second embodiment. It is a schematic diagram shown.
　まず、図１１（ａ）に示す、乾燥用金属部材ＭＤ３を準備する。乾燥用金属部材ＭＤ３は、第１方向に延在する複数の凹部と、第１方向と交差する第２方向に延在する複数の凹部とが形成された金属板、すなわち、格子形状に凹部が形成された金属板からなる。格子の間隔（ピッチ）は、例えば１０ｍｍであり、格子幅は、例えば５ｍｍである。乾燥用金属部材ＭＤ３は、例えばステンレス、鉄（Ｆｅ）、金（Ａｕ）、銀（Ａｇ）、鉄（Ｆｅ）合金またはニッケル（Ｎｉ）合金などからなる。 First, a drying metal member MD3 shown in FIG. 11 (a) is prepared. The drying metal member MD3 is a metal plate in which a plurality of recesses extending in the first direction and a plurality of recesses extending in the second direction intersecting the first direction are formed, that is, the recesses are in a lattice shape. It consists of a formed metal plate. The interval (pitch) of the lattice is, for example, 10 mm, and the lattice width is, for example, 5 mm. The drying metal member MD3 is made of, for example, stainless steel, iron (Fe), gold (Au), silver (Ag), iron (Fe) alloy, nickel (Ni) alloy, or the like.
　次に、図１１（ｂ）に示すように、その表面上に正極合剤層ＰＥＦが塗布された集電箔ＰＥＰを、乾燥用金属部材ＭＤ３上に搭載する。その後、乾燥用金属部材ＭＤ３上に搭載された集電箔ＰＥＰを、例えば１２０℃の熱風乾燥炉内に搬送して、集電箔ＰＥＰの表面上に塗布された、スラリー塗布後の正極合剤層ＰＥＦを乾燥させる。ここで、上記第１方向と集電箔ＰＥＰの搬送方向とは一致する。集電箔ＰＥＰの搬送速度は、例えば５～１００ｍ／分である。量産製造時には、乾燥用金属部材ＭＤ３を集電箔ＰＥＰと共に熱風乾燥炉中を一定速度で搬送することにより、生産性を維持することができる。 Next, as shown in FIG. 11B, the current collector foil PEP having the positive electrode mixture layer PEF applied on the surface thereof is mounted on the drying metal member MD3. Thereafter, the current collector foil PEP mounted on the drying metal member MD3 is conveyed into, for example, a 120 ° C. hot-air drying furnace, and applied to the surface of the current collector foil PEP. The layer PEF is dried. Here, the said 1st direction and the conveyance direction of current collection foil PEP correspond. The conveying speed of the current collector foil PEP is, for example, 5 to 100 m / min. At the time of mass production, productivity can be maintained by conveying the drying metal member MD3 together with the current collector foil PEP in a hot air drying furnace at a constant speed.
　上記乾燥工程を経ることにより、図１１（ｃ）に示すように、乾燥用金属部材ＭＤ３の複数の凸部上に位置しなかった格子形状の正極合剤層ＰＥＦの空隙率が、乾燥用金属部材ＭＤ３の複数の凸部上に位置した正極合剤層ＰＥＦの空隙率よりも高くなる。これにより、例えば幅５ｍｍの空隙率の高い正極合剤層ＰＥＦＨが格子形状に形成される。その後、乾燥した正極合剤層ＰＥＦをプレス圧縮することにより、正極が製造される。負極も同様に製造することができる。 By passing through the drying step, as shown in FIG. 11C, the porosity of the lattice-shaped positive electrode mixture layer PEF that is not located on the plurality of convex portions of the drying metal member MD3 is reduced to the drying metal. It becomes higher than the porosity of the positive electrode mixture layer PEF located on the plurality of convex portions of the member MD3. Thereby, for example, a positive electrode mixture layer PEFH having a high porosity of 5 mm in width is formed in a lattice shape. Then, a positive electrode is manufactured by press-compressing the dried positive electrode mixture layer PEF. The negative electrode can be produced in the same manner.
　（３）次に、捲回工程について、図１２を用いて説明する。図１２は、本実施例２による空隙率の高い領域が格子形状となっている電極合剤層が形成された電極を有する電極捲回体の第４例の模式図である。 (3) Next, the winding process will be described with reference to FIG. FIG. 12 is a schematic diagram of a fourth example of an electrode winding body having an electrode in which an electrode mixture layer in which a high porosity region according to the second embodiment has a lattice shape is formed.
　図１２に示すように、電極捲回体ＷＲＦの第４例は、軸心ＣＲの回りに捲回された正極ＰＥＬ、セパレータＳＰ１，ＳＰ２および負極ＮＥＬから構成される。そして、正極ＰＥＬでは、空隙率の高い正極合剤層ＰＥＦＨが格子形状に形成されており、負極ＮＥＬでは、空隙率の高い負極合剤層ＮＥＦＨが格子形状に形成されている。 As shown in FIG. 12, the fourth example of the electrode winding body WRF includes a positive electrode PEL wound around the axis CR, separators SP1 and SP2, and a negative electrode NEL. In the positive electrode PEL, the positive electrode mixture layer PEFH having a high porosity is formed in a lattice shape, and in the negative electrode NEL, the negative electrode mixture layer NEFH having a high porosity is formed in a lattice shape.
　なお、本実施例２では、空隙率の高い電極合剤層を一定の間隔（ピッチ）で設けた格子形状に形成したが、これに限定されるものではない。例えばランダムに凸部が形成された乾燥用金属部材を用いて、空隙率の高い電極合剤層を不定の間隔で設けた網目形状に形成することもできる。 In Example 2, the electrode mixture layer having a high porosity is formed in a lattice shape provided at a constant interval (pitch), but is not limited thereto. For example, it is possible to form a mesh shape in which electrode mixture layers having a high porosity are provided at indefinite intervals using a drying metal member on which convex portions are randomly formed.
　このように、本実施例２によれば、空隙率の高い電極合剤層を格子形状とすることにより、リチウムイオンの拡散経路を広く確保することができるので、前述した実施例１よりもリチウムイオン電池の充放電時の内部抵抗を低減することができる。 As described above, according to the second embodiment, since the electrode mixture layer having a high porosity has a lattice shape, a wide diffusion path of lithium ions can be secured. The internal resistance during charging / discharging of the ion battery can be reduced.
　本実施例３による電極の製造方法について、以下に説明する。 The electrode manufacturing method according to the third embodiment will be described below.
　本実施例３と、前述した実施例１、２とが相違する点は、集電箔の表面上に形成された電極合剤層の乾燥方式である。すなわち、前述した実施例１、２では、乾燥炉において、例えば１２０℃の熱風によりスラリー塗布後の電極合剤層を乾燥させたが、本実施例３では、乾燥炉において、赤外線ランプを用いてスラリー塗布後の電極合剤層を乾燥させる。 The difference between the third embodiment and the first and second embodiments described above is the drying method of the electrode mixture layer formed on the surface of the current collector foil. That is, in Examples 1 and 2 described above, the electrode mixture layer after slurry application was dried with, for example, 120 ° C. hot air in a drying furnace. In Example 3, an infrared lamp was used in the drying furnace. The electrode mixture layer after slurry application is dried.
　（１）まず、前述した実施例１による塗工工程と同様にして、集電箔ＰＥＰの表面上に正極合剤層ＰＥＦを形成し、集電箔ＮＥＰの表面上に負極合剤層ＮＥＦを形成する。 (1) First, the positive electrode mixture layer PEF is formed on the surface of the current collector foil PEP, and the negative electrode mixture layer NEF is formed on the surface of the current collector foil NEP in the same manner as in the coating step according to Example 1 described above. Form.
　（２）次に、乾燥工程について、図１３（ａ）、（ｂ）および（ｃ）を用いて説明する。ここでは、正極の製造方法について説明するが、負極の製造方法もほぼ同様である。図１３（ａ）、（ｂ）および（ｃ）はそれぞれ、本実施例３によるスラリー塗布後の乾燥工程で用いる遮蔽板、乾燥中の正極合剤層および乾燥後の正極合剤層を示す模式図である。 (2) Next, a drying process is demonstrated using FIG. 13 (a), (b) and (c). Here, the manufacturing method of the positive electrode will be described, but the manufacturing method of the negative electrode is substantially the same. FIGS. 13A, 13B, and 13C are schematic diagrams showing a shielding plate used in the drying step after slurry application according to Example 3, a positive electrode mixture layer being dried, and a positive electrode mixture layer after being dried, respectively. FIG.
　まず、図１３（ａ）に示す、遮蔽板ＳＨを準備する。遮蔽板ＳＨには、第１方向に遮蔽部ＳＨＰと開口部（スリット）ＯＰとが交互に形成されている。第１方向の遮蔽部ＳＨＰおよび開口部ＯＰの幅はそれぞれ、例えば１ｍｍであり、開口部ＯＰは、第１方向と直交する第２方向に延びてストライプ状に形成されている。遮蔽板ＳＨには、セラミック板または金属板などを用いることができる。 First, a shielding plate SH shown in FIG. 13 (a) is prepared. In the shielding plate SH, shielding portions SHP and openings (slits) OP are alternately formed in the first direction. The widths of the shielding part SHP and the opening OP in the first direction are each 1 mm, for example, and the opening OP is formed in a stripe shape extending in the second direction orthogonal to the first direction. A ceramic plate or a metal plate can be used for the shielding plate SH.
　次に、図１３（ｂ）に示すように、正極合剤層ＰＥＦの表面に対向する方向に、遮蔽板ＳＨを介して赤外線ランプが設置されており、赤外線ランプから赤外線を照射して、正極合剤層ＰＥＦを乾燥させる。赤外線ランプには、ハロゲンランプなどを用いることができる。ここで、集電箔ＰＥＰの搬送方向に、遮蔽部ＳＨＰと開口部ＯＰとが交互となるように、遮蔽板ＳＨが配置される。すなわち、上記第１方向と集電箔ＰＥＰの搬送方向とは一致し、集電箔ＰＥＰの搬送方向に対して交差する方向に開口部ＯＰが延在するように、遮蔽板ＳＨは配置される。量産製造時には、遮蔽板ＳＨを集電箔ＰＥＰと共に乾燥炉中を一定速度で搬送することにより、生産性を維持することができる。 Next, as shown in FIG.13 (b), the infrared lamp is installed through the shielding board SH in the direction facing the surface of positive mix layer PEF, and infrared rays are irradiated from an infrared lamp, and positive electrode The mixture layer PEF is dried. As the infrared lamp, a halogen lamp or the like can be used. Here, the shielding plates SH are arranged so that the shielding portions SHP and the openings OP are alternately arranged in the conveying direction of the current collector foil PEP. That is, the shielding plate SH is disposed so that the first direction and the transport direction of the current collector foil PEP coincide with each other and the opening OP extends in a direction intersecting the transport direction of the current collector foil PEP. . During mass production, productivity can be maintained by transporting the shielding plate SH together with the current collector foil PEP through the drying furnace at a constant speed.
　上記乾燥工程を経ることにより、図１３（ｃ）に示すように、赤外線が遮蔽されて照射されていない正極合剤層ＰＥＦの空隙率が、赤外線が照射された正極合剤層ＰＥＦの空隙率よりも高くなる。これにより、集電箔ＰＥＰの搬送方向に、空隙率の高い正極合剤層と、空隙率の低い正極合剤層とが交互に形成される。集電箔ＰＥＰの搬送方向の空隙率の低い正極合剤層の幅および空隙率の高い正極合剤層の幅は、例えば１ｍｍである。その後、乾燥した正極合剤層ＰＥＦをプレス圧縮することにより、正極が製造される。負極も同様に製造することができる。 By passing through the drying step, as shown in FIG. 13 (c), the porosity of the positive electrode mixture layer PEF that is shielded from infrared rays and is not irradiated is equal to the porosity of the positive electrode mixture layer PEF that is irradiated with infrared rays. Higher than. Thereby, a positive electrode mixture layer having a high porosity and a positive electrode mixture layer having a low porosity are alternately formed in the conveying direction of the current collector foil PEP. The width of the positive electrode mixture layer having a low porosity in the transport direction of the current collector foil PEP and the width of the positive electrode mixture layer having a high porosity are, for example, 1 mm. Then, a positive electrode is manufactured by press-compressing the dried positive electrode mixture layer PEF. The negative electrode can be produced in the same manner.
　（３）次に、前述した実施例１、２と同様にして、電極とセパレータとを積層し捲回することにより、缶蓋－缶底方向に空隙率の高い電極合剤層が形成された電極捲回体が形成される。 (3) Next, in the same manner as in Examples 1 and 2, the electrode mixture layer having a high porosity was formed in the can lid-can bottom direction by laminating and winding the electrode and the separator. An electrode winding body is formed.
　赤外線ランプを用いた乾燥方式は局所加熱が可能であり、前述した実施例１、２で用いた熱風乾燥方式よりも、互いに空隙率の異なる電極合剤層の幅が狭いパターンを形成することができる。これにより、リチウムイオンの拡散経路を短縮することができるので、前述した実施例１、２よりもリチウムイオン電池の充放電時の内部抵抗を低減することができる。 The drying method using the infrared lamp can be locally heated, and can form a pattern in which the width of the electrode mixture layer having a different porosity is narrower than the hot air drying method used in Examples 1 and 2 described above. it can. Thereby, since the diffusion path | route of lithium ion can be shortened, the internal resistance at the time of charging / discharging of a lithium ion battery can be reduced rather than Example 1, 2 mentioned above.
　また、乾燥工程に用いる遮蔽板ＳＨの開口部ＯＰを任意の形状にすることで、空隙率の異なる電極合剤層が任意のパターン（例えば図３（ａ）および（ｂ）、図５または図１２に示すようなパターン）に形成された電極捲回体を得ることができる。 Further, by forming the opening OP of the shielding plate SH used in the drying process into an arbitrary shape, the electrode mixture layers having different porosity can be formed in an arbitrary pattern (for example, FIGS. 3A and 3B, FIG. 5 or FIG. The electrode winding body formed in a pattern as shown in FIG.
　以上、本発明者によってなされた発明を実施の形態に基づき具体的に説明したが、本発明は前記実施の形態に限定されるものではなく、その要旨を逸脱しない範囲で種々変更可能であることはいうまでもない。 As mentioned above, the invention made by the present inventor has been specifically described based on the embodiment. However, the present invention is not limited to the embodiment, and various modifications can be made without departing from the scope of the invention. Needless to say.
　本実施の形態では、リチウムイオン電池を例に挙げて、本発明の技術的思想について説明したが、本発明の技術的思想は、リチウムイオン電池に限定されるものではない。例えば正極、負極、および正極と負極とを電気的に分離するセパレータを備える蓄電デバイス（例えば電池またはキャパシタなど）に幅広く適用することができる。 In the present embodiment, the technical idea of the present invention has been described by taking a lithium ion battery as an example, but the technical idea of the present invention is not limited to the lithium ion battery. For example, it can be widely applied to an electricity storage device (for example, a battery or a capacitor) including a positive electrode, a negative electrode, and a separator that electrically separates the positive electrode and the negative electrode.
　本発明は、例えばリチウムイオン電池に代表される電池を製造する製造業に幅広く利用することができる。 The present invention can be widely used in the manufacturing industry for manufacturing batteries represented by, for example, lithium ion batteries.
ＡＳ　活物質
ＢＤ　結着材（バインダ）
ＣＡ　導電助剤
ＣＡＰ　電池蓋
ＣＲ　軸芯
ＣＳ　外装缶
ＥＦ　電極合剤層
ＥＬ　電極
ＥＰ　集電体（集電箔）
ＬＩＢ　リチウムイオン電池
ＭＤ１，ＭＤ２，ＭＤ３　乾燥用金属部材
ＭＰ　金属板
ＭＷ　金属線
ＮＥＦ　負極合剤層
ＮＥＦＨ　空隙率の高い負極合剤層
ＮＥＦＬ　空隙率の低い負極合剤層
ＮＥＬ　負極
ＮＥＰ　集電箔
ＮＴ　負極リード板
ＮＴＡＢ　負極集電タブ
ＮＲ　負極リング
ＯＰ　開口部（スリット）
Ｐ１　第１ピッチ
Ｐ２　第２ピッチ
ＰＥＦ　正極合剤層
ＰＥＦＨ　空隙率の高い正極合剤層
ＰＥＦＬ　空隙率の低い正極合剤層
ＰＥＬ　正極
ＰＥＰ　集電箔
ＰＲ　正極リング
ＰＴ　正極リード板
ＰＴＡＢ　正極集電タブ
ＳＨ　遮蔽板
ＳＨＰ　遮蔽部
ＳＰ１，ＳＰ２　セパレータ
ＷＲＦ　電極捲回体 AS active material BD binder (binder)
CA Conductive aid CAP Battery cover CR Shaft core CS Exterior can EF Electrode mixture layer EL Electrode EP Current collector (current collector foil)
LIB Lithium ion batteries MD1, MD2, MD3 Drying metal member MP Metal plate MW Metal wire NEF Negative electrode mixture layer NEFH High porosity negative electrode mixture layer NEFL Low porosity negative electrode mixture layer NEL Negative electrode NEP Current collector foil NT Negative electrode Lead plate NTAB Negative electrode current collector tab NR Negative electrode ring OP Opening (slit)
P1 First pitch P2 Second pitch PEF Positive electrode mixture layer PEFH High porosity positive electrode mixture layer PEFL Low porosity positive electrode mixture layer PEL Positive electrode PEP Current collecting foil PR Positive electrode ring PT Positive electrode lead plate PTAB Positive electrode current collecting tab SH Shielding plate SHP Shielding part SP1, SP2 Separator WRF Electrode winding body

Claims (15)

  1. 　第１集電箔の表面上に正極合剤層が形成された正極と、
    　第２集電箔の表面上に負極合剤層が形成された負極と、
    　前記正極と前記負極とを絶縁するセパレータと、
    　前記正極と前記負極との間で充放電反応が行われる電解液と、
    を備えるリチウムイオン電池であって、
    　前記正極合剤層は、前記第１集電箔の表面上に形成された互いに空隙率が異なる２以上の合剤層から構成され、
    　前記負極合剤層は、前記第２集電箔の表面上に形成された互いに空隙率が異なる２以上の合剤層から構成され、
    　前記正極合剤層を構成する２以上の合剤層のそれぞれに含まれる活物質の粒度分布が同じであり、
    　前記負極合剤層を構成する２以上の合剤層のそれぞれに含まれる活物質の粒度分布が同じである、リチウムイオン電池。     A positive electrode in which a positive electrode mixture layer is formed on the surface of the first current collector foil;
    A negative electrode in which a negative electrode mixture layer is formed on the surface of the second current collector foil;
    A separator for insulating the positive electrode and the negative electrode;
    An electrolytic solution in which a charge / discharge reaction is performed between the positive electrode and the negative electrode;
    A lithium ion battery comprising:
    The positive electrode mixture layer is composed of two or more mixture layers formed on the surface of the first current collector foil and having different porosity.
    The negative electrode mixture layer is composed of two or more mixture layers having different porosity formed on the surface of the second current collector foil,
    The particle size distribution of the active material contained in each of the two or more mixture layers constituting the positive electrode mixture layer is the same,
    A lithium ion battery in which the particle size distribution of the active material contained in each of the two or more mixture layers constituting the negative electrode mixture layer is the same.
  2. 　請求項１記載のリチウムイオン電池において、
    　互いに対向する位置に缶蓋と缶底とを有する外装缶の内部に、積層された前記正極と、前記セパレータと、前記負極とを軸芯の回りに捲回した電極捲回体が形成され、
    　前記正極合剤層は、第１空隙率を有する第１合剤層と、前記第１空隙率よりも高い第２空隙率を有する第２合剤層とを有し、
    　前記負極合剤層は、第３空隙率を有する第３合剤層と、前記第３空隙率よりも高い第４空隙率を有する第４合剤層とを有し、
    　前記第２合剤層および前記第４合剤層は、前記外装缶の前記缶底側から前記缶蓋へ向かってまたは前記外装缶の前記缶蓋側から前記缶底へ向かって形成されている、リチウムイオン電池。     The lithium ion battery according to claim 1,
    Inside the outer can having a can lid and a can bottom at positions facing each other, an electrode winding body is formed by winding the stacked positive electrode, the separator, and the negative electrode around an axis,
    The positive electrode mixture layer has a first mixture layer having a first porosity, and a second mixture layer having a second porosity higher than the first porosity,
    The negative electrode mixture layer has a third mixture layer having a third porosity, and a fourth mixture layer having a fourth porosity higher than the third porosity,
    The second mixture layer and the fourth mixture layer are formed from the can bottom side of the outer can toward the can lid or from the can lid side of the outer can to the can bottom. , Lithium ion battery.
  3. 　請求項２記載のリチウムイオン電池において、
    　前記電極捲回体の捲回方向と直交する缶蓋－缶底方向の前記第２合剤層の長さは、前記缶蓋－缶底方向の前記正極合剤層の幅の２／３倍以上、かつ、１倍以下であり、
    　前記缶蓋－缶底方向の前記第４合剤層の長さは、前記缶蓋－缶底方向の前記負極合剤層の幅の２／３倍以上、かつ、１倍以下である、リチウムイオン電池。     The lithium ion battery according to claim 2,
    The length of the second mixture layer in the can lid-can bottom direction perpendicular to the winding direction of the electrode winding body is 2/3 times the width of the positive electrode mixture layer in the can lid-can bottom direction. Above and below 1 times
    The length of the fourth mixture layer in the can lid-can bottom direction is not less than 2/3 times and not more than 1 times the width of the negative electrode mixture layer in the can lid-can bottom direction. Ion battery.
  4. 　請求項２記載のリチウムイオン電池において、
    　前記電極捲回体の捲回方向と直交する缶蓋－缶底方向の前記第２合剤層の長さは、前記缶蓋－缶底方向の前記正極合剤層の幅と等しく、
    　前記缶蓋－缶底方向の前記第４合剤層の長さは、前記缶蓋－缶底方向の前記負極合剤層の幅と等しく、
    　前記第１合剤層と前記第２合剤層とが、前記捲回方向に互いに交互に形成され、
    　前記第３合剤層と前記第４合剤層とが、前記捲回方向に互いに交互に形成されている、リチウムイオン電池。     The lithium ion battery according to claim 2,
    The length of the second mixture layer in the can lid-can bottom direction perpendicular to the winding direction of the electrode winding body is equal to the width of the positive electrode mixture layer in the can lid-can bottom direction,
    The length of the fourth mixture layer in the can lid-can bottom direction is equal to the width of the negative electrode mixture layer in the can lid-can bottom direction,
    The first mixture layer and the second mixture layer are alternately formed in the winding direction,
    The lithium ion battery, wherein the third mixture layer and the fourth mixture layer are alternately formed in the winding direction.
  5. 　請求項２記載のリチウムイオン電池において、
    　前記第２合剤層の前記第２空隙率は、前記第１合剤層の前記第１空隙率よりも１１体積％～２５体積％高く、
    　前記第４合剤層の前記第４空隙率は、前記第３合剤層の前記第３空隙率よりも１１体積％～２５体積％高い、リチウムイオン電池。     The lithium ion battery according to claim 2,
    The second porosity of the second mixture layer is 11% by volume to 25% by volume higher than the first porosity of the first mixture layer,
    The lithium ion battery, wherein the fourth porosity of the fourth mixture layer is 11 volume% to 25 volume% higher than the third porosity of the third mixture layer.
  6. 　請求項１記載のリチウムイオン電池において、
    　前記正極合剤層は、第１空隙率を有する第１合剤層と、前記第１空隙率よりも高い第２空隙率を有する第２合剤層を有し、
    　前記負極合剤層は、第３空隙率を有する第３合剤層と、前記第３空隙率よりも高い第４空隙率を有する第４合剤層を有し、
    　前記第１集電箔の表面上に、複数の前記第１合剤層が互いに離間して形成され、複数の前記第１合剤層の周囲に前記第２合剤層が形成され、
    　前記第２集電箔の表面上に、複数の前記第３合剤層が互いに離間して形成され、複数の前記第３合剤層の周囲に前記第４合剤層が形成されている、リチウムイオン電池。     The lithium ion battery according to claim 1,
    The positive electrode mixture layer has a first mixture layer having a first porosity, and a second mixture layer having a second porosity higher than the first porosity,
    The negative electrode mixture layer has a third mixture layer having a third porosity, and a fourth mixture layer having a fourth porosity higher than the third porosity,
    On the surface of the first current collector foil, a plurality of the first mixture layers are formed apart from each other, and the second mixture layer is formed around the plurality of the first mixture layers,
    On the surface of the second current collector foil, a plurality of the third mixture layers are formed apart from each other, and the fourth mixture layer is formed around the plurality of the third mixture layers. Lithium ion battery.
  7. 　請求項６記載のリチウムイオン電池において、
    　前記第２合剤層は、前記第１集電箔の表面上に格子形状に形成され、
    　前記第４合剤層は、前記第２集電箔の表面上に格子形状に形成されている、リチウムイオン電池。     The lithium ion battery according to claim 6,
    The second mixture layer is formed in a lattice shape on the surface of the first current collector foil,
    The fourth mixture layer is a lithium ion battery formed in a lattice shape on the surface of the second current collector foil.
  8. 　請求項６記載のリチウムイオン電池において、
    　前記第２合剤層の前記第２空隙率は、前記第１合剤層の前記第１空隙率よりも１１体積％～２５体積％高く、
    　前記第４合剤層の前記第４空隙率は、前記第３合剤層の前記第３空隙率よりも１１体積％～２５体積％高い、リチウムイオン電池。     The lithium ion battery according to claim 6,
    The second porosity of the second mixture layer is 11% by volume to 25% by volume higher than the first porosity of the first mixture layer,
    The lithium ion battery, wherein the fourth porosity of the fourth mixture layer is 11 volume% to 25 volume% higher than the third porosity of the third mixture layer.
  9. 　（ａ）集電箔の表面上に、スラリー状の電極材料を塗布して、電極合剤層を形成する工程、
    　（ｂ）第１方向に走行する前記集電箔の表面上の前記電極合剤層を乾燥させる工程、
    を含み、
    　前記（ｂ）工程において、前記集電箔の裏面の一部を金属部材に接触させて、熱風乾燥炉で前記電極合剤層を乾燥させる、リチウムイオン電池の製造方法。     (A) A step of applying a slurry-like electrode material on the surface of the current collector foil to form an electrode mixture layer;
    (B) drying the electrode mixture layer on the surface of the current collector foil traveling in the first direction;
    Including
    In the step (b), a part of the back surface of the current collector foil is brought into contact with a metal member, and the electrode mixture layer is dried in a hot air drying furnace.
  10. 　請求項９記載のリチウムイオン電池の製造方法において、
    　前記金属部材は、前記第１方向に互いに離間して配置された複数の金属線を有する、リチウムイオン電池の製造方法。     In the manufacturing method of the lithium ion battery according to claim 9,
    The method of manufacturing a lithium ion battery, wherein the metal member includes a plurality of metal wires that are spaced apart from each other in the first direction.
  11. 　請求項９記載のリチウムイオン電池の製造方法において、
    　前記金属部材は、互いに離間して配置された複数の凸部を有する金属板である、リチウムイオン電池の製造方法。     In the manufacturing method of the lithium ion battery according to claim 9,
    The said metal member is a manufacturing method of a lithium ion battery which is a metal plate which has several convex parts arrange | positioned mutually spaced apart.
  12. 　請求項１１記載のリチウムイオン電池の製造方法において、
    　前記金属板は、平面視において格子形状の凹部を有する、リチウムイオン電池の製造方法。     In the manufacturing method of the lithium ion battery according to claim 11,
    The said metal plate is a manufacturing method of a lithium ion battery which has a grid | lattice-shaped recessed part in planar view.
  13. 　（ａ）集電箔の表面上に、スラリー状の電極材料を塗布して、電極合剤層を形成する工程、
    　（ｂ）第１方向に走行する前記集電箔の表面上の前記電極合剤層を乾燥させる工程、
    を含み、
    　前記（ｂ）工程において、前記集電箔の表面側から、複数の開口部が形成された遮蔽板を介して赤外線を照射する、リチウムイオン電池の製造方法。     (A) A step of applying a slurry-like electrode material on the surface of the current collector foil to form an electrode mixture layer;
    (B) drying the electrode mixture layer on the surface of the current collector foil traveling in the first direction;
    Including
    The manufacturing method of a lithium ion battery which irradiates infrared rays through the shielding board in which the several opening part was formed in the said (b) process from the surface side of the said collector foil.
  14. 　請求項１３記載のリチウムイオン電池の製造方法において、
    　前記複数の開口部は、前記第１方向に互いに離間し、前記第１方向と交差する第２方向に延在する、リチウムイオン電池の製造方法。     In the manufacturing method of the lithium ion battery according to claim 13,
    The plurality of openings are spaced apart from each other in the first direction and extend in a second direction intersecting the first direction.
  15. 　請求項１３記載のリチウムイオン電池の製造方法において、
    　前記複数の開口部が形成されていない前記遮蔽板の他の部分は、平面視において格子形状である、リチウムイオン電池。     In the manufacturing method of the lithium ion battery according to claim 13,
    The other part of the shielding plate in which the plurality of openings are not formed is a lithium ion battery having a lattice shape in plan view.
PCT/JP2014/080595 2014-11-19 2014-11-19 Lithium ion battery and production method therefor WO2016079821A1 (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113196518A (en) * 2018-11-13 2021-07-30 日本汽车能源株式会社 Lithium ion secondary battery and method for manufacturing same
WO2024095686A1 (en) * 2022-10-31 2024-05-10 パナソニックエナジー株式会社 Positive electrode for secondary battery, and secondary battery

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH09320569A (en) * 1996-05-30 1997-12-12 Ricoh Co Ltd Nonaqueous secondary battery
JP2007042385A (en) * 2005-08-02 2007-02-15 Nissan Motor Co Ltd Electrode for battery
JP2008508672A (en) * 2004-07-27 2008-03-21 オクシス・エナジー・リミテッド Improvements to electrode structures in batteries
JP2010186736A (en) * 2009-01-13 2010-08-26 Panasonic Corp Anode plate for nonaqueous battery, electrode group for nonaqueous battery and its manufacturing method, and cylindrical nonaqueous secondary battery and its manufacturing method
JP2014523624A (en) * 2011-07-12 2014-09-11 アプライド マテリアルズ インコーポレイテッド Method for producing a change in porosity of a lithium ion battery electrode film

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH09320569A (en) * 1996-05-30 1997-12-12 Ricoh Co Ltd Nonaqueous secondary battery
JP2008508672A (en) * 2004-07-27 2008-03-21 オクシス・エナジー・リミテッド Improvements to electrode structures in batteries
JP2007042385A (en) * 2005-08-02 2007-02-15 Nissan Motor Co Ltd Electrode for battery
JP2010186736A (en) * 2009-01-13 2010-08-26 Panasonic Corp Anode plate for nonaqueous battery, electrode group for nonaqueous battery and its manufacturing method, and cylindrical nonaqueous secondary battery and its manufacturing method
JP2014523624A (en) * 2011-07-12 2014-09-11 アプライド マテリアルズ インコーポレイテッド Method for producing a change in porosity of a lithium ion battery electrode film

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113196518A (en) * 2018-11-13 2021-07-30 日本汽车能源株式会社 Lithium ion secondary battery and method for manufacturing same
CN113196518B (en) * 2018-11-13 2023-08-01 日本汽车能源株式会社 Lithium ion secondary battery and method for manufacturing same
WO2024095686A1 (en) * 2022-10-31 2024-05-10 パナソニックエナジー株式会社 Positive electrode for secondary battery, and secondary battery

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