WO2019198146A1 - Electrode group, non-aqueous electrolyte battery, and battery pack - Google Patents

Electrode group, non-aqueous electrolyte battery, and battery pack Download PDF

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Publication number
WO2019198146A1
WO2019198146A1 PCT/JP2018/015064 JP2018015064W WO2019198146A1 WO 2019198146 A1 WO2019198146 A1 WO 2019198146A1 JP 2018015064 W JP2018015064 W JP 2018015064W WO 2019198146 A1 WO2019198146 A1 WO 2019198146A1
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Prior art keywords
negative electrode
positive electrode
electrode
separator
electrode group
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PCT/JP2018/015064
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French (fr)
Japanese (ja)
Inventor
泰章 村司
志子田　将貴
矢嶋　亨
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株式会社 東芝
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Priority to JP2020512969A priority Critical patent/JP6952883B2/en
Priority to PCT/JP2018/015064 priority patent/WO2019198146A1/en
Publication of WO2019198146A1 publication Critical patent/WO2019198146A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • H01M50/491—Porosity
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or 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
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • 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

  • Embodiments of the present invention relate to an electrode group, a nonaqueous electrolyte battery, and a battery pack.
  • an electrode group is provided.
  • This electrode group includes a positive electrode, a negative electrode including a lithium titanium composite oxide, and a separator disposed at least between the positive electrode and the negative electrode.
  • the permeability of the separator is 10% or more and 20% or less.
  • the separator includes a porous fiber sheet including pores having a pore area of 8 ⁇ 10 ⁇ 9 m 2 or more and fibers.
  • a nonaqueous electrolyte battery includes the electrode group according to the first embodiment and a nonaqueous electrolyte.
  • a battery pack is provided.
  • This battery pack includes the nonaqueous electrolyte battery according to the second embodiment.
  • FIG. 1 is a partially developed schematic perspective view of an example electrode group according to the first embodiment.
  • FIG. 2 is an enlarged cross-sectional view of part A of the electrode group shown in FIG.
  • FIG. 3 is a schematic perspective view of another example electrode group according to the first embodiment.
  • 4 is a cross-sectional view taken along line XX of the electrode group shown in FIG.
  • FIG. 5 is an image obtained by subjecting one SEM image of a separator included in another example electrode group according to the first embodiment to a binarization process.
  • FIG. 6 is an SEM image of a porous fiber sheet included in a separator included in an example electrode group according to the first embodiment.
  • FIG. 7 is an exploded schematic perspective view of an example nonaqueous electrolyte battery according to the second embodiment.
  • FIG. 8 is a block diagram showing an electric circuit of an example battery pack according to the third embodiment.
  • an electrode group is provided.
  • This electrode group includes a positive electrode, a negative electrode including a lithium titanium composite oxide, and a separator disposed at least between the positive electrode and the negative electrode.
  • the permeability of the separator is 10% or more and 20% or less.
  • the separator includes a porous fiber sheet including pores having a pore area of 8 ⁇ 10 ⁇ 9 m 2 or more and fibers.
  • the permeability of the separator is more specifically the main surface of the separator, for example, the surface facing the positive electrode or the negative electrode in the direction in which the separator is facing the positive electrode or the negative electrode, that is, the electrode group.
  • An image (SEM image) obtained by observing with a scanning electron microscope (SEM) from the direction in which the positive electrode and the negative electrode face each other is obtained by subjecting it to a binarization process described in detail below. It can be said that it is the ratio of the area of the portion where no separator material, for example, fibers, occupies the image.
  • the separator included in the electrode group according to the first embodiment has a relatively large number of through holes penetrating in the direction in which the positive electrode and the negative electrode face each other because the permeability is 10% or more and 20% or less. Can have.
  • the separator included in the electrode group according to the first embodiment includes a porous fiber sheet including pores and fibers having a pore area of 8 ⁇ 10 ⁇ 9 m 2 or more.
  • the separator includes a porous fiber sheet including pores and fibers having a permeability of 10% to 20% and a pore area of 8 ⁇ 10 ⁇ 9 m 2 or more.
  • Such an electrode group can promote fluid movement in a direction in which the positive electrode and the negative electrode face each other.
  • the electrode group according to the first embodiment can diffuse components that cause gas generation through the separator to the entire electrode group without locally staying in any member of the electrode group.
  • lithium titanium composite oxide included in the negative electrode can react with moisture to generate gas.
  • the electrode group according to the first embodiment even if moisture is contained in the negative electrode, at least a part of this moisture can be moved to the separator and the positive electrode.
  • the release of this component from the electrode group is only through the exposed surface of the negative electrode.
  • this component can be used not only for the exposed surface of the negative electrode but also for the positive electrode and the separator.
  • the electrode group according to the first embodiment can sufficiently reduce the retention amount of components that cause gas generation.
  • the electrode group according to the first embodiment can exhibit the above-described action even in a state where the electrode group is incorporated in a nonaqueous electrolyte battery.
  • the lithium-titanium composite oxide included in the negative electrode can exhibit electrical insulation in a state where Li is not inserted.
  • the separator included in the electrode group according to the first embodiment can have a relatively large number of through holes penetrating in the direction in which the positive electrode and the negative electrode face each other as described above. Even if the positive electrode and the negative electrode come into contact with each other, Li is immediately released from the lithium titanium composite oxide at the contact portion of the negative electrode. Thereby, the contact part of a negative electrode will be in an insulating state, and can prevent further electricity supply.
  • the lithium-titanium composite oxide can exhibit a lithium occlusion and release potential (operating potential) that is sufficiently higher than the oxidation-reduction potential of lithium. Therefore, even if the nonaqueous electrolyte battery including the electrode group according to the first embodiment is repeatedly subjected to rapid charge / discharge, it is possible to prevent lithium dendrite from being deposited on the negative electrode.
  • the lithium dendrite occurs in an electrode group including a separator having a relatively large number of through holes penetrating in the direction in which the positive electrode and the negative electrode face each other, the lithium dendrite grows along the through holes, and the conductivity between the positive electrode and the negative electrode is increased. It can be a path and an electrical short can occur.
  • the electrode group according to the first embodiment can prevent the occurrence of such an electrical short circuit due to the lithium dendrite. Therefore, the electrode according to the first embodiment can provide a nonaqueous electrolyte battery that can actually function.
  • the electrode group according to the first embodiment can realize a nonaqueous electrolyte battery that can sufficiently suppress gas generation.
  • the life performance of the nonaqueous electrolyte battery can be improved by suppressing the amount of gas generated in the nonaqueous electrolyte battery. Therefore, the electrode group according to the first embodiment can also realize a nonaqueous electrolyte battery capable of exhibiting excellent life performance.
  • the electrode group according to the first embodiment includes a positive electrode, a negative electrode, and a separator.
  • the positive electrode can include, for example, a positive electrode current collector and a positive electrode material layer.
  • the positive electrode current collector can have, for example, a belt-like planar shape.
  • the positive electrode material layer can be disposed on both surfaces or one surface of the positive electrode current collector.
  • the positive electrode current collector can also include a portion that does not carry the positive electrode material layer on any surface. This part can also serve as a positive electrode current collecting tab.
  • the positive electrode may include a positive electrode current collecting tab that is separate from the positive electrode current collector.
  • the positive electrode material layer can contain a positive electrode active material.
  • the positive electrode material layer can further contain a conductive agent and a binder as necessary.
  • the negative electrode can include, for example, a negative electrode current collector and a negative electrode material layer.
  • the negative electrode current collector can have, for example, a belt-like planar shape.
  • the negative electrode material layer can be disposed on both surfaces or one surface of the negative electrode current collector.
  • the negative electrode current collector can also include a portion that does not carry the negative electrode material layer on any surface. This part can also serve as a negative electrode current collecting tab.
  • the negative electrode material layer can contain a negative electrode active material.
  • the negative electrode material layer can further contain a conductive agent and a binder as necessary.
  • the lithium titanium composite oxide can be contained in the negative electrode material layer as a negative electrode active material, for example.
  • the negative electrode active material may be made of a lithium titanium composite oxide, or may be a mixture of a lithium titanium composite oxide and another negative electrode active material.
  • the negative electrode active material preferably contains 50% by weight or more of lithium titanium composite oxide, more preferably contains 80% by weight or more, and most preferably consists of lithium titanium composite oxide.
  • An electrode group produced using a combination of a negative electrode that does not include a lithium titanium composite oxide and the separator included in the electrode group according to the first embodiment is electrically connected to the positive electrode and the negative electrode through the through hole of the separator. May continue to flow. Such an electrode group may not realize a battery that actually functions.
  • the separator is disposed at least between the positive electrode and the negative electrode.
  • the positive electrode material layer and the negative electrode material layer can face each other via a separator.
  • the porous fiber sheet may exist other than between the positive electrode and the negative electrode.
  • a part of the porous fiber sheet may be disposed in the outermost layer of the electrode group for the purpose of preventing energization between the electrode group and other members.
  • the separator has a permeability of 10% or more and 20% or less.
  • the separator includes a porous fiber sheet including pores having a pore area of 8 ⁇ 10 ⁇ 9 m 2 or more and fibers.
  • the electrode group in which the permeability of the separator is less than 10% cannot sufficiently promote the movement of fluid in the direction in which the positive electrode and the negative electrode face each other. Moreover, it is difficult for the electrode group in which the permeability of the separator exceeds 20% to exhibit sufficient insulation between the positive electrode and the negative electrode, and it is not possible to provide a practically usable nonaqueous electrolyte battery. .
  • the permeability of the separator is 10% or more and 20% or less, in the electrode group that does not include pores in which the porous fiber sheet has a pore area of 8 ⁇ 10 ⁇ 9 m 2 or more, The movement of the fluid in the direction facing the negative electrode cannot be sufficiently promoted.
  • the permeability of the separator is preferably 12% or more and 18% or less, and more preferably 15% or more and 18% or less.
  • the porous fiber sheet preferably includes pores having a pore area of 8.5 ⁇ 10 ⁇ 9 m 2 or more, and pores having a pore area of 10 ⁇ 10 ⁇ 9 m 2 or more. It is more preferable to contain.
  • the porous fiber sheet can include, for example, pores having a pore area of 25 ⁇ 10 ⁇ 9 m 2 or less, and pores having a pore area of 20 ⁇ 10 ⁇ 9 m 2 or less. It is more preferable to contain.
  • the fibers included in the porous fiber sheet preferably have an average width of 10 ⁇ m or more and 40 ⁇ m or less.
  • the separator included in the electrode group of this preferred embodiment can exhibit excellent retainability of the nonaqueous electrolyte.
  • the charge carrier for example, Li ions
  • the electrode group of this preferred embodiment can realize a non-aqueous electrolyte battery that can exhibit better life performance.
  • the average width of the fibers is more preferably 10 ⁇ m or more and 30 ⁇ m or less.
  • the average width of the fibers can be measured from an image obtained by observing the porous fiber sheet with a scanning electron microscope from the direction in which the separator faces the positive electrode or the negative electrode.
  • the method for measuring the average width of the fibers will be described in detail below.
  • the basis weight of the porous fiber sheet is preferably 5 g / m 2 or more and 20 g / m 2 or less, and more preferably 8 g / m 2 or more and 15 g / m 2 or less.
  • the porous fiber sheet preferably includes pores having a diameter of 50 ⁇ m or more, and more preferably includes pores having a diameter of 80 ⁇ m or more.
  • the pores contained in the porous fiber sheet preferably have a diameter of 300 ⁇ m or less, and more preferably have a diameter of 200 ⁇ m or less.
  • the porous fiber sheet can exhibit an air permeability based on the Gurley method of 0.1 second / 100 ml or more and 1 second / 100 ml or less.
  • the air permeability based on the Gurley method can be measured by a method defined in JIS C2300.
  • the porous fiber sheet desirably exhibits air permeability based on the Gurley method of 0.1 second / 100 ml or more and 0.5 second / 100 ml or less.
  • the positive electrode material layer and the negative electrode material layer may be porous, for example.
  • the positive electrode includes a porous positive electrode material layer
  • the negative electrode includes a negative electrode material layer.
  • the negative electrode material layer can include a lithium titanium composite oxide.
  • the separator can be disposed at least between the positive electrode material layer and the negative electrode material layer. In the electrode group according to this aspect, the fluid that has moved through the separator can be more smoothly discharged from the exposed surfaces of the positive electrode material layer, the separator, and the negative electrode material layer, so that the components that cause gas generation can be discharged. The amount of residence in the electrode group can be further reduced.
  • the electrode group according to the first embodiment can have various structures.
  • the electrode group can have a wound structure.
  • the electrode group having a wound structure can have, for example, a flat shape or a cylindrical shape.
  • the wound electrode group can be produced, for example, by the following procedure. First, a separator is made by laminating one separator, a positive electrode, another separator, and a negative electrode in this order. Next, this laminate is wound, for example, so that the negative electrode is positioned outside. By extracting the winding core, a cylindrical wound electrode group can be obtained. For example, a flat wound electrode group can be obtained by subjecting this cylindrical electrode group to pressing. Alternatively, the electrode group may have a stacked structure.
  • the electrode group having a stacked structure is obtained, for example, by alternately stacking a positive electrode and a negative electrode so that a separator is sandwiched between them.
  • the electrode group according to the first embodiment may have a structure other than a wound type and a stacked type structure.
  • Negative electrode for the negative electrode current collector, for example, a metal foil or an alloy foil is used.
  • the thickness of the current collector is desirably 20 ⁇ m or less, more preferably 15 ⁇ m or less.
  • the metal foil include copper foil and aluminum foil. When using aluminum foil, it is preferable that the purity of aluminum foil is 99 weight% or more.
  • the alloy foil include stainless steel foil and aluminum alloy foil.
  • the aluminum alloy in the aluminum alloy foil preferably contains at least one element selected from the group consisting of magnesium, zinc and silicon. The content of transition metals such as iron, copper, nickel and chromium in the alloy components is preferably 1% by weight or less.
  • lithium titanium composite oxide examples include a lithium titanium composite oxide having a spinel crystal structure.
  • titanic acid having a composition represented by Li 4 + x Ti 5 O 12 x varies in the range of 0 ⁇ x ⁇ 3 by charge / discharge reaction
  • Lithium can be mentioned.
  • a lithium titanium composite oxide having a ramsdellite type crystal structure As an example of a ramsdellite-type titanium-containing oxide, a composite oxide having a composition represented by Li 2 + y Ti 3 O 7 (y changes in the range of ⁇ 1 ⁇ y ⁇ 3 by charge / discharge reaction) is given. Can be mentioned.
  • negative electrode active materials other than lithium-titanium composite oxides include carbonaceous materials capable of occluding and releasing lithium (eg, graphite, hard carbon, soft carbon, graphene), titanium-containing oxides other than lithium-titanium composite oxides, sulfides things, nitrides such SnB 0.4 P 0.6 O 3.1 amorphous tin composite oxide such as, for example, tin silicon composite oxides such as SnSiO 3, for example, silicon oxides such as SiO, a metal oxide other than the titanium-containing oxide ( For example, a tungsten oxide such as WO 3 ).
  • the negative electrode active material other than the lithium titanium composite oxide one kind or a mixture of two or more kinds of the above negative electrode active materials can be used.
  • the sulfide, nitride, amorphous tin composite oxide, tin silicon composite oxide and metal oxide include, for example, a compound containing lithium at the time of synthesis and a compound not containing lithium at the time of synthesis. Further, some titanium-containing oxides do not contain lithium during synthesis (for example, titanium dioxide having a monoclinic crystal structure, niobium titanium composite oxide having an orthorhombic crystal structure, etc.). .
  • the negative electrode active material not containing lithium at the time of synthesis can contain lithium, for example, by charging.
  • titanium-containing oxides other than lithium-titanium composite oxide include, for example, titanium-containing oxides having anatase type crystal structure, titanium-containing oxides having rutile type crystal structure, bronze type or monoclinic type A titanium-containing oxide having a crystal structure and a metal composite oxide containing Ti and at least one element selected from the group consisting of P, V, Sn, Cu, Ni, Nb, and Fe are included.
  • Examples of the metal composite oxide containing Ti and at least one element selected from the group consisting of P, V, Sn, Cu, Ni, Nb, and Fe include TiO 2 —P 2 O 5 , TiO 2. —V 2 O 5 , TiO 2 —P 2 O 5 —SnO 2 , TiO 2 —P 2 O 5 —MeO (Me is at least one element selected from the group consisting of Cu, Ni and Fe) And niobium titanium composite oxide (eg, Nb 2 TiO 7 ).
  • This metal complex oxide preferably has a low crystallinity and has a structure in which a crystalline phase and an amorphous phase coexist, or a microstructure in which an amorphous phase exists alone. With such a microstructure, cycle performance can be greatly improved.
  • composition of the titanium-containing oxide having an anatase type, rutile type or bronze type (ie, monoclinic type) crystal structure can be represented by TiO 2 .
  • the sulfide examples include titanium sulfide such as TiS 2 , molybdenum sulfide such as MoS 2, and iron sulfide such as FeS, FeS 2 , and Li x FeS 2 (0 ⁇ x ⁇ 2).
  • nitride examples include lithium cobalt nitride (for example, Li x Co y N, where 0 ⁇ x ⁇ 4 and 0 ⁇ y ⁇ 0.5).
  • Examples of the conductive agent include carbon-containing materials (acetylene black, ketjen black, graphite, etc.) and metal powder.
  • binder examples include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), fluorine rubber, and styrene butadiene rubber.
  • the basis weight of the negative electrode material layer is desirably in the range of 10 g / m 2 to 300 g / m 2 .
  • a more preferable range is 20 g / m 2 or more and 200 g / m 2 or less.
  • the density of the negative electrode material layer is desirably in the range of 1.5 g / cm 3 or more and 3.2 g / cm 3 or less. A more preferable range is 1.8 g / cm 3 or more and 2.5 g / cm 3 or less.
  • the negative electrode can be produced, for example, by the following procedure. First, a conductive agent and a binder are added to a powdered negative electrode active material, and these are suspended in an appropriate solvent to obtain a suspension (slurry). Next, this suspension is applied to both sides or one side of a belt-like current collector, and the coating film is dried. At this time, the suspension uncoated portion may be left in a part of the current collector. Subsequently, a negative electrode can be obtained by pressing a coating film into a strip electrode.
  • the compounding ratio of the negative electrode active material, the conductive agent and the binder is preferably in the range of 73 to 98% by weight of the negative electrode active material, 0 to 20% by weight of the conductive agent, and 2 to 7% by weight of the binder.
  • Positive electrode The positive electrode current collector is preferably formed from an aluminum foil or an aluminum alloy foil.
  • the purity of the aluminum foil is preferably 99% by weight or more.
  • As the aluminum alloy an alloy containing one or more elements selected from the group consisting of magnesium, zinc and silicon is preferable.
  • the content of transition metals such as iron, copper, nickel and chromium is preferably 1% by weight or less.
  • the thickness of the positive electrode current collector is preferably 20 ⁇ m or less, more preferably 15 ⁇ m or less.
  • the positive electrode active material examples include various oxides and sulfides.
  • lithium nickel composite oxide for example, Li x NiO 2 (0 ⁇ x ⁇ 1)
  • lithium cobalt composite oxide for example, Li x CoO 2 (0 ⁇ x ⁇ 1)
  • lithium nickel cobalt composite oxide for example, Li x Ni 1 -yz Co y M z O 2 (M is at least one element selected from the group consisting of Al, Cr and Fe, and 0 ⁇ x ⁇ 1, 0 ⁇ y ⁇ 0.5) , 0 ⁇ z ⁇ 0.1)
  • lithium manganese cobalt composite oxide for example, Li x Mn 1-yz Co y M z O 2 (M is selected
  • M is composed of Mg, Al, Si, Ti, Zn, Zr, Ca and Sn.
  • compounds having a composition represented by represents at least one element selected from the group) can be mentioned.
  • conductive polymer materials such as polyaniline and polypyrrole, disulfide-based polymer materials, organic materials such as sulfur (S) and carbon fluoride, and inorganic materials are also included.
  • the type of positive electrode active material can be one type or two or more types.
  • Examples of the conductive agent include carbon black, graphite (graphite), graphene, fullerenes, coke and the like. Of these, carbon black and graphite are preferred. Examples of carbon black include acetylene black, ketjen black, and furnace black.
  • binder examples include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), polyacrylic acid, and fluorine rubber.
  • the basis weight of the positive electrode material layer is desirably in the range of 10 g / m 2 to 300 g / m 2 .
  • a more preferable range is 20 g / m 2 or more and 220 g / m 2 or less.
  • the density of the positive electrode material layer is desirably in the range of 2 g / m 3 or more and 4.5 g / m 3 or less. A more preferable range is 2.8 g / cm 3 or more and 4 g / cm 3 or less.
  • the positive electrode can be produced, for example, by the following procedure. First, a conductive agent and a binder are added to the positive electrode active material, and these are suspended in an appropriate solvent to obtain a suspension (slurry). Next, this suspension is applied to both sides or one side of a belt-like current collector such as an aluminum foil, and the coating film is dried. At this time, the suspension uncoated portion may be left in a part of the current collector. Subsequently, a positive electrode can be obtained by pressing a coating film into a strip electrode.
  • the compounding ratio of the positive electrode active material, the conductive agent and the binder is preferably in the range of 80 to 95% by weight of the positive electrode active material, 3 to 20% by weight of the conductive agent, and 2 to 7% by weight of the binder.
  • the separator includes a porous fiber sheet including pores and fibers.
  • the material of the fiber is not particularly limited, and examples thereof include at least one polymer selected from the group consisting of polyolefin, cellulose, polyester, polyvinyl alcohol, polyamide, polyimide, polytetrafluoroethylene, and vinylon.
  • the fiber may consist of one of the above materials or may contain two or more of the above materials.
  • the porous fiber sheet may be a non-woven fabric containing such fibers, or may be a porous film.
  • the separator may contain a material other than the porous fiber sheet.
  • the separator may contain inorganic particles, for example.
  • the separator may be made of a porous fiber sheet.
  • the separator may be a porous fiber sheet.
  • the thickness of the porous fiber sheet is preferably 4 ⁇ m or more and 30 ⁇ m or less, and more preferably 8 ⁇ m or more and 25 ⁇ m or less.
  • the thickness of the separator is also preferably 4 ⁇ m or more and 30 ⁇ m or less, and more preferably 8 ⁇ m or more and 25 ⁇ m or less.
  • the separator including a porous fiber sheet including pores and fibers having a porosity of 10% or more and 20% or less and a pore area of 8 ⁇ 10 ⁇ 9 m 2 or more has a basis weight of, for example, 5 g. / M 2 or more and 20 g / m 2 or less, and the paper can be produced by making papers by selecting the amount of fibers and press conditions so that the average width of the fibers is 10 ⁇ m or more and 40 ⁇ m or less.
  • the porous fiber sheet may be directly formed by supplying a raw material solution on the positive electrode and / or negative electrode surface, for example. The porous fiber sheet thus formed may be subjected to pressing.
  • FIG. 1 is a partially developed schematic perspective view of an example electrode group according to the first embodiment.
  • FIG. 2 is an enlarged cross-sectional view of part A of the electrode group shown in FIG.
  • the electrode group 1 of the first example shown in FIGS. 1 and 2 is a flat wound electrode group.
  • the electrode group 1 includes a negative electrode 2 shown in FIGS. 1 and 2, a positive electrode 3 shown in FIGS. 1 and 2, and two separators 4 shown in FIGS.
  • the negative electrode 2 includes a strip-shaped negative electrode current collector 2a made of, for example, a metal foil, and a negative electrode current collector tab 2c made of one end parallel to the long side of the negative electrode current collector 2a.
  • the negative electrode material layer 2b contains a lithium titanium composite oxide.
  • the positive electrode 3 includes, for example, a strip-like positive electrode current collector 3a made of a metal foil, and a positive electrode current collector tab 3c made of one end parallel to the long side of the positive electrode current collector 3a.
  • the separator 4 includes a portion sandwiched between the negative electrode material layer 2b and the positive electrode material layer 3b. As shown in FIG. 1, each separator 4 has a belt-like planar shape extending in the MD direction (machine direction). In FIG. 1, the direction perpendicular to the MD direction of the separator 4 is indicated as TD (transverse direction).
  • the separator 4 includes a porous fiber sheet that has a permeability of 10% or more and 20% or less and includes pores and fibers having a pore area of 8 ⁇ 10 ⁇ 9 m 2 or more. Therefore, in the electrode group 1 of the first example, it is possible to promote fluid movement in the direction in which the positive electrode 3 and the negative electrode 2 face each other (for example, the direction indicated by the line segment II ′ in FIG. 2).
  • the negative electrode material layer 2b includes a lithium titanium composite oxide. As a result, the electrode group 1 of the first example can realize a non-aqueous electrolyte battery that can sufficiently suppress gas generation for the reason described above.
  • the electrode group 1 shown in FIGS. 1 and 2 can be manufactured by the following procedure. First, one separator 4, the positive electrode 3, another separator 4, and the negative electrode 2 are laminated in this order to obtain a laminate. When laminating, the MD directions of the two separators 4 are aligned. The direction in which the negative electrode current collector 2 a and the positive electrode current collector 3 a extend is also made parallel to the MD direction of the separator 4. Further, as shown in FIG. 1, each member is placed in the TD direction so that the negative electrode current collecting tab 2 c does not overlap the separator 4 and the positive electrode 3 and so that the positive electrode current collecting tab 3 c does not overlap the separator 4 and the negative electrode 2. Lay and stack.
  • the obtained laminate is wound around the winding axis w so that the positive electrode 3 comes outside the negative electrode 2 to obtain a wound body.
  • the positive electrode current collecting tab 3c protrudes from the negative electrode 2 in a direction parallel to the winding axis w.
  • the negative electrode current collecting tab 2c protrudes from the positive electrode 3 in a direction parallel to the winding axis w and opposite to the direction in which the positive electrode current collecting tab 3c protrudes. .
  • the wound electrode group 1 having a flat shape shown in FIG. 1 can be obtained by subjecting the wound body thus obtained to a press.
  • FIG. 3 is a schematic perspective view of another example electrode group according to the first embodiment. 4 is a cross-sectional view taken along line XX of the electrode group shown in FIG.
  • the electrode group 1 shown in FIGS. 3 and 4 is an electrode group having a laminated structure. As shown in FIG. 4, the electrode group 1 includes a plurality (for example, two sheets) of negative electrodes 2 1 and 2 2 , a plurality (for example, two sheets) of positive electrodes 3 1 and 3 2, and a plurality (for example, five sheets) of separators. 4 is included.
  • each of the negative electrode current collectors 2a of the negative electrodes 2 1 and 2 2 includes a portion (negative electrode current collection tab) that does not carry the negative electrode material layer 2b on any surface.
  • each negative electrode material layer 2b of the negative electrodes 2 1 and 2 2 contains a lithium titanium composite oxide.
  • one positive electrode 31 has a positive electrode material layer (positive electrode active material-containing layer) formed on the surfaces of both the strip-shaped positive electrode current collector 3a and the positive electrode current collector 3a. 3b.
  • the other of the positive electrode 3 includes a band-like positive electrode current collector 3a, and a positive electrode layer 3b formed on one surface of the positive electrode current collector 3a.
  • each of the positive electrode current collectors 3a of the positive electrodes 3 1 and 3 2 includes a portion (positive electrode current collecting tab) that does not carry the positive electrode material layer 3b on any surface.
  • the negative electrode 2 2 is superimposed ing.
  • the negative electrode 2 of one on 2 of the negative electrode material layer 2b separator 4 are superposed, the positive electrode 3 1 are stacked thereon.
  • the negative electrode material layer 2b of the negative electrode 2 sandwiched between the separator 4, and faces the one of the positive electrode material layer 3b of the cathode 3 1.
  • one separator 4 is superimposed on the other of the positive electrode material layer 3b of the cathode 3 1, negative electrode 2 1 are stacked thereon.
  • the positive electrode material layer 3b of the cathode 3 sandwiched between the separator 4, and face one of the negative electrode material layer 2b of the negative electrode 2 1.
  • One separator 4 is stacked on the other negative electrode material layer 2 b of the negative electrode 21, and the positive electrode 3 2 is stacked thereon.
  • the positive electrode material layer 3b of the cathode 3 2 sandwiched between the separator 4, and faces the other of the negative electrode material layer 2b of the negative electrode 2 1.
  • the remaining separator 4 are stacked on the cathode 3 2 positive electrode current collector 3a.
  • the plurality of negative electrodes 2 1 and 2 2 , the plurality of positive electrodes 3 1 and 3 2, and the plurality of separators 4 are stacked as described above to form the electrode group 1. As shown in FIG. 4, among the porous fiber sheets 4, the uppermost layer and the lowermost porous fiber sheet 4 of the electrode group 1 are not sandwiched between the positive electrode and the negative electrode.
  • each of the negative electrode current collecting tabs described above is electrically connected to the negative electrode lead 7 shown in FIG.
  • each of the positive electrode current collecting tabs described above is electrically connected to the positive electrode lead 6 shown in FIG.
  • the tip of the positive electrode lead 6 and the tip of the negative electrode lead 7 extend from the electrode group 1 in opposite directions.
  • Each separator 4 shows a Toruchi rate is 20% or less than 10%, pore area comprises a porous fibrous sheet containing pores and the fibers is 8 ⁇ 10 -9 m 2 or more. Therefore, the electrode group 1 in the second example, the positive electrode 3 1 and the negative electrode 2 2 and the direction of opposing the positive electrode 3 1 and the negative electrode 2 1 a is a direction opposed, and the negative electrode 2 1 and the positive electrode 3 2 facing The movement of the fluid in the direction, that is, the direction indicated by the line segment II-II ′ in FIG. 4 can be promoted.
  • the negative electrode material layer 2b includes a lithium titanium composite oxide.
  • the nonaqueous electrolyte battery is discharged to a state of SOC 0%. Subsequently, the non-aqueous electrolyte battery having a battery charge depth of SOC 0% is disassembled in a glove box under an argon atmosphere. An electrode group is taken out from the disassembled nonaqueous electrolyte battery.
  • the electrode group taken out is washed with an appropriate solvent such as methyl ethyl carbonate. After washing, the electrode group is dried.
  • an electrode group is obtained.
  • the above process can be omitted.
  • ⁇ Measurement method of permeability of separator contained in electrode group, measurement method of pore area of pores contained in porous fiber sheet> [Scanning electron microscope observation] The arbitrary five places of the taken-out separator are observed with a scanning electron microscope (SEM). The observation magnification is 500 times.
  • the measurement direction is the direction in which the main surface of the separator and the positive electrode or the negative electrode face each other, that is, the direction in which the positive electrode and the negative electrode face each other in the electrode group including the separator to be measured.
  • the maximum through-hole area can be obtained. This area is defined as the maximum area [m 2 ] of pores included in the porous fiber sheet included in the separator. By this analysis, the maximum diameter [ ⁇ m] of the pores included in the porous fiber sheet included in the separator can also be obtained.
  • the five SEM images obtained previously are subjected to image processing according to the following procedure.
  • the following image processing can be performed by software including an application capable of performing processing for detecting the edge of the fiber and the edge of the active material from the image and processing for binarizing the image.
  • an image processing program “Image J” free software (development: National Institutes of Health), English version ver. 1.48) can be used for image processing.
  • processing is performed so that a portion surrounded by the edge of the active material becomes a bright portion.
  • the fact that the active material is reflected means that the fiber of the porous fiber sheet does not exist in that portion.
  • the edge of the material other than the porous fiber sheet is obtained from the obtained SEM image in the binarization process (1) described above. Is detected.
  • the image is binarized so that a portion where a material other than the fiber is present becomes a bright portion in addition to a portion where the fiber is present.
  • FIG. 5 shows an image obtained by subjecting the SEM image of the separator included in the example electrode group according to the first embodiment to a binarization process.
  • the dark part is a part where the separator material does not exist.
  • This portion is a portion where the negative electrode (negative electrode material layer) was observed through the through hole of the porous fiber sheet in the direction in which the positive electrode and the negative electrode faced each other in the electrode group having the separator to be measured.
  • the permeability of the separator shown in FIG. 5 was 18%.
  • the maximum pore area of the pores contained in the porous fiber sheet was 20 ⁇ 10 ⁇ 9 m 2 .
  • ⁇ Measuring method of average width of fiber> [Scanning electron microscope observation] As described above, arbitrary five portions of the separator taken out from the electrode group are observed with a scanning electron microscope. Here, the observation magnification is 1000 times.
  • the measurement direction is a direction in which the positive electrode and the negative electrode face each other in the electrode group including the porous fiber sheet to be measured.
  • FIG. 6 shows one SEM image of the porous fiber sheet included in the example electrode group according to the first embodiment.
  • the average width of the fibers included in the SEM image shown in FIG. 6 is 19 ⁇ m.
  • the basis weight [g / m 2 ] of the porous fiber sheet can be measured by a method defined in JIS P8124.
  • the air permeability of the porous fiber sheet based on the Gurley method can be measured by the method defined in JIS-P8117.
  • composition and crystal structure of the positive electrode active material and the negative electrode active material contained in the electrode group can be identified by the following procedure.
  • ICP Inductively Coupled Plasma
  • the measurement target elements are Li, Al, Mn, Ba, Ca, Ce, Co, Cr, Cu, Fe, Hf, K, La, Mg, Na, Ni, Pb, Si, Ti, Y, Zn, and Zr. .
  • composition of the negative electrode active material can be identified by performing the same measurement.
  • X-ray diffraction (XRD) measurement XRD measurement is performed on the dried positive electrode.
  • the range of the diffraction angle (2 ⁇ ) is 10 ° to 90 °, and the X-ray diffraction intensity is measured by 0.02 °.
  • the XRD measurement result is obtained.
  • the pattern of the intrinsic peak of the active material estimated from the active material composition is estimated from the database.
  • the crystal structure of the positive electrode active material contained in the positive electrode layer can be identified by comparing the estimated X-ray pattern with the actually measured X-ray pattern.
  • the composition of the negative electrode active material can be identified by performing the same measurement.
  • the actual X-ray pattern obtained by the XRD measurement includes peaks derived from the plurality of types of positive electrode active materials.
  • a peak derived from each active material may or may not overlap with a peak derived from another active material.
  • the composition and mixing ratio of each positive electrode active material contained in the positive electrode can be known by the XRD measurement and ICP analysis.
  • composition and mixing ratio of each positive electrode active material contained in the positive electrode material layer are determined by SEM observation, EDX analysis, and EELS analysis. Specifically, it is as follows.
  • a piece of about 2 cm ⁇ 2 cm is cut out from the dried positive electrode with a cutter or the like.
  • the section of the cut piece is irradiated with argon ions accelerated at an acceleration voltage of 2 to 6 kV to obtain a flat section.
  • composition of some active material particles included in the cross section of the positive electrode is analyzed using an SEM with EDX and EELS.
  • EDX the elements B to U can be quantitatively analyzed.
  • Li can be quantitatively analyzed by EELS.
  • the composition of each positive electrode active material contained in the positive electrode material layer can be known.
  • the mixing ratio of the positive electrode active material in the positive electrode can be known from the overall composition of the positive electrode active material and the composition of each positive electrode active material.
  • the composition and mixing ratio of each negative electrode active material can be known by following the same procedure as that for the positive electrode active material.
  • an electrode group includes a positive electrode, a negative electrode, and a separator disposed at least between the positive electrode and the negative electrode.
  • the permeability of the separator is 10% or more and 20% or less.
  • the separator includes a porous fiber sheet including pores having a pore area of 8 ⁇ 10 ⁇ 9 m 2 or more and fibers. This electrode group can promote the movement of fluid in the direction in which the positive electrode and the negative electrode face each other.
  • the negative electrode includes a lithium titanium composite oxide.
  • a nonaqueous electrolyte battery According to the second embodiment, a nonaqueous electrolyte battery is provided.
  • This nonaqueous electrolyte battery includes the electrode group according to the first embodiment and a nonaqueous electrolyte.
  • the nonaqueous electrolyte can be held, for example, in an electrode group.
  • the electrode group may be impregnated with a nonaqueous electrolyte.
  • the nonaqueous electrolyte battery according to the second embodiment can further include a positive electrode terminal and a negative electrode terminal.
  • the positive electrode terminal can function as a conductor for electrons to move between the positive electrode and an external circuit by being partially connected to a part of the positive electrode.
  • the positive terminal can be connected to, for example, a positive current collector, particularly a positive current collector tab.
  • a part of the negative electrode terminal is electrically connected to a part of the negative electrode, whereby the negative electrode terminal can serve as a conductor for electrons to move between the negative electrode and the external terminal.
  • the negative electrode terminal can be connected to, for example, a negative electrode current collector, particularly a negative electrode current collector tab.
  • the nonaqueous electrolyte battery according to the second embodiment can further include an exterior member.
  • the exterior member can accommodate the electrode group and the nonaqueous electrolyte. A part of each of the positive electrode terminal and the negative electrode terminal can be extended from the exterior member.
  • the electrode group according to the first embodiment can smoothly discharge the gas that may cause gas generation to the outside, and as a result, the amount of retention of these gases in the electrode group can be reduced. Can be reduced. Thanks to that, the nonaqueous electrolyte battery according to the second embodiment can sufficiently suppress gas generation. Further, for example, in a series of steps for producing a non-aqueous electrolyte battery using the electrode group according to the first embodiment, the electrode group according to the first embodiment is subjected to drying, so that the electrode group is Moisture can be released to the outside more easily than the electrode group in which the permeability of the separator is less than 10%. Thereby, a non-aqueous electrolyte battery that has a small amount of water and can sufficiently suppress gas generation can be provided.
  • Electrode group Regarding the electrode group refer to the description of the electrode group according to the first embodiment.
  • Non-aqueous electrolyte can contain a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. Further, the non-aqueous solvent may contain a polymer.
  • electrolyte salt examples include LiPF 6 , LiBF 4 , Li (CF 3 SO 2 ) 2 N (bistrifluoromethanesulfonylamide lithium; commonly known as LiTFSI), LiCF 3 SO 3 (commonly known as LiTFS), and Li (C 2 F 5 SO 2) 2 N (bis pentafluoroethanesulfonyl amide lithium; called LiBETI), LiClO 4, LiAsF 6 , LiSbF 6, bisoxalato Lato lithium borate (LiB (C 2 O 4) 2 ( known as LiBOB)), difluoro (oxalato) Lithium borate (LiF 2 BC 2 O 4 ), difluoro (trifluoro-2-oxide-2-trifluoro-methylpropionate (2-)-0,0) lithium borate (LiBF 2 (OCOOC (CF 3 ) 2) (aka LiBF 2 (HHIB))), lithium difluorophosphate (LiPO 2 2)
  • electrolyte salts may be used alone or in combination of two or more.
  • LiPF 6 LiBF 4 , lithium bisoxalatoborate (LiB (C 2 O 4 ) 2 (commonly called LiBOB)), lithium difluoro (oxalato) borate (LiF 2 BC 2 O 4 ), difluoro (trifluoro-2 -Oxide-2-trifluoro-methylpropionate (2-)-0,0) lithium borate (LiBF 2 (OCOOC (CF 3 ) 2 ) (commonly known as LiBF 2 (HHIB))), lithium difluorophosphate (LiPO 2 F 2) is preferred.
  • the electrolyte salt concentration is preferably in the range of 0.5M to 3M. Thereby, the performance when a high load current is passed can be improved.
  • the non-aqueous solvent is not particularly limited, but propylene carbonate (PC), ethylene carbonate (EC), 1,2-dimethoxyethane (DME), ⁇ -butyrolactone (GBL), tetrahydrofuran (THF), 2 -Methyltetrahydrofuran (2-MeHF), 1,3-dioxolane, sulfolane, acetonitrile (AN), diethyl carbonate (DEC), dimethyl carbonate (DMC), methyl ethyl carbonate (MEC), dipropyl carbonate (DPC), etc. It is done.
  • PC propylene carbonate
  • EC ethylene carbonate
  • DME 1,2-dimethoxyethane
  • GBL ⁇ -butyrolactone
  • THF tetrahydrofuran
  • 2-MeHF 2 -Methyltetrahydrofuran
  • 1,3-dioxolane 1,3-dioxolane
  • An additive may be added to this non-aqueous electrolyte.
  • Vinylene carbonate (VC) fluoro vinylene carbonate, methyl vinylene carbonate, fluoromethyl vinylene carbonate, ethyl vinylene carbonate, propyl vinylene carbonate, butyl vinylene carbonate, dimethyl vinylene carbonate, diethyl
  • VA vinylene acetate
  • VA vinylene butyrate
  • vinylene hexanate vinylene crotonate
  • catechol carbonate propane sultone
  • propane sultone propane sultone
  • butane sultone One kind or two or more kinds of additives can be used.
  • (C) Exterior Member As the exterior member, for example, a laminate film having a thickness of 0.5 mm or less or a metal container having a thickness of 3 mm or less can be used. More preferably, the metal container has a thickness of 0.5 mm or less.
  • a resin container may also be used. Examples of the material forming the resin container include polyolefin, polyvinyl chloride, polystyrene resin, acrylic resin, phenol resin, polyphenylene resin, fluorine resin, and the like.
  • Examples of the shape of the exterior member that is, the battery shape, include a flat type (thin type), a square type, a cylindrical type, a coin type, and a button type.
  • the battery can be applied to, for example, a small-sized application loaded on a portable electronic device or the like, and a large-sized application loaded on a two-wheel to four-wheeled vehicle.
  • the laminate film a multilayer film including a metal layer and a resin layer sandwiching the metal layer is used.
  • the metal layer is preferably an aluminum foil or an aluminum alloy foil for weight reduction.
  • the resin layer for example, a polymer material such as polypropylene (PP), polyethylene (PE), nylon, polyethylene terephthalate (PET) can be used.
  • PP polypropylene
  • PE polyethylene
  • PET polyethylene terephthalate
  • the laminate film can be formed into the shape of an exterior member by sealing by heat sealing.
  • Metal containers are made of aluminum or aluminum alloy.
  • the aluminum alloy preferably contains at least one element selected from the group consisting of magnesium, zinc and silicon.
  • transition metals such as iron, copper, nickel, and chromium, are contained in an alloy, it is preferable that the quantity shall be 100 ppm or less.
  • the negative electrode terminal can be formed from aluminum or an aluminum alloy containing at least one element selected from the group consisting of Mg, Ti, Zn, Mn, Fe, Cu, and Si. In order to reduce the contact resistance with the negative electrode current collector, the negative electrode terminal is preferably formed from the same material as the negative electrode current collector.
  • the positive electrode terminal is formed from aluminum or an aluminum alloy containing at least one element selected from the group consisting of Mg, Ti, Zn, Ni, Cr, Mn, Fe, Cu, and Si. It is preferable. In order to reduce the contact resistance with the positive electrode current collector, the positive electrode terminal is preferably formed of the same material as the positive electrode current collector.
  • FIG. 7 is an exploded schematic perspective view of an example nonaqueous electrolyte battery according to the second embodiment.
  • the battery 10 shown in FIG. 7 is a sealed rectangular nonaqueous electrolyte battery.
  • the nonaqueous electrolyte battery 10 includes an outer can 11, a sealing plate 12, a positive electrode terminal 13, a negative electrode terminal 14, an electrode group 1, and a nonaqueous electrolyte (not shown).
  • An exterior member is composed of the exterior can 11 and the sealing plate 12.
  • the outer can 11 has a bottomed rectangular tube shape and is formed of a metal such as aluminum, an aluminum alloy, iron, or stainless steel.
  • the electrode group 1 shown in FIG. 7 has the same structure as the wound electrode group 1 having a flat shape described with reference to FIGS. 1 and 2 except for the following points.
  • the positive electrode current collecting tab 3 c and the negative electrode current collecting tab 2 c are each divided into two bundles with the vicinity of the winding axis w of the electrode group 1 as a boundary.
  • the conductive sandwiching member 5 includes first and second sandwiching portions 5a and 5b that are substantially U-shaped, and a connecting portion that electrically connects the first sandwiching portion 5a and the second sandwiching portion 5b. 5c.
  • first and second sandwiching portions 5a and 5b that are substantially U-shaped, and a connecting portion that electrically connects the first sandwiching portion 5a and the second sandwiching portion 5b. 5c.
  • the positive electrode current collecting tab 3c and the negative electrode current collecting tab 2c one bundle is sandwiched by the first sandwiching portion 5a, and the other bundle is sandwiched by the second sandwiching portion 5b.
  • portions of the electrode group 1 other than the positive electrode current collecting tab 3 c and the negative electrode current collecting tab 2 c are covered with an insulating seal 8.
  • a non-aqueous electrolyte (not shown) is held in a state where the electrode group 1 is impregnated.
  • the positive electrode lead 6 includes a rectangular support plate 6a, a through-hole 6b opened in the support plate 6a, and strip-shaped current collectors 6c and 6d that are bifurcated from the support plate 6a and extend downward.
  • the negative electrode lead 7 includes a rectangular support plate 7a, a through hole 7b opened in the support plate 7a, a bifurcated bifurcated branch from the support plate 7a, and strip-shaped current collectors 7c and 7d extending downward.
  • the current collectors 6c and 6d of the positive electrode lead 6 sandwich the clamping member 5 attached to the positive electrode current collecting tab 3c therebetween.
  • the current collector 6 c is in contact with the first clamping part 5 a of the clamping member 5.
  • the current collector 6d is in contact with the second clamping unit 5b.
  • the current collecting parts 6c and 6d, the first and second clamping parts 5a and 5b, and the positive electrode current collecting tab 3c are joined by, for example, ultrasonic welding. Thereby, the positive electrode 3 and the positive electrode lead 6 of the electrode group 1 are electrically connected via the positive electrode current collection tab 3c.
  • the current collecting portions 7c and 7d of the negative electrode lead 7 sandwich the holding member 5 attached to the negative electrode current collecting tab 2c therebetween.
  • the current collector 7 c is in contact with the first clamping part 5 a of the clamping member 5.
  • the current collector 7d is in contact with the second clamping unit 5b.
  • the current collecting parts 7c and 7d, the first and second clamping parts 5a and 5b, and the negative electrode current collecting tab 2c are joined by, for example, ultrasonic welding. Thereby, the negative electrode 2 and the negative electrode lead 7 of the electrode group 1 are electrically connected via the negative electrode current collection tab 2c.
  • the material of the clamping member 5 attached to the positive electrode lead 6 and the positive electrode current collecting tab 3c is not particularly limited, but is preferably the same as the material of the positive electrode terminal 13.
  • the positive electrode terminal 13 for example, aluminum or an aluminum alloy is used.
  • the material of the holding member 5 attached to the negative electrode lead 7 and the negative electrode current collecting tab 2 c is not particularly limited, but is preferably the same as the material of the negative electrode terminal 14.
  • the negative electrode terminal 14 for example, aluminum, aluminum alloy, copper, nickel, nickel-plated iron, or the like is used.
  • the material of the terminal is aluminum or aluminum alloy
  • the material of the lead connected to the terminal is preferably aluminum or aluminum alloy.
  • the terminal is made of copper, it is desirable that the material of the lead connected to the terminal is made of copper or the like.
  • the rectangular plate-shaped sealing plate 12 is seam welded to the opening of the outer can 11 by, for example, a laser.
  • the sealing plate 12 is made of, for example, a metal such as aluminum, an aluminum alloy, iron, or stainless steel. It is desirable that the sealing plate 12 and the outer can 11 are formed of the same type of metal.
  • the positive terminal 13 is electrically connected to the support plate 6 a of the positive lead 6.
  • the negative electrode terminal 14 is electrically connected to the support plate 7 a of the negative electrode lead 7.
  • Insulating gaskets 15 are disposed between the positive terminal 13 and the sealing plate 12 and between the negative terminal 14 and the sealing plate 12, respectively.
  • the insulating gasket 15 is preferably a resin molded product.
  • nonaqueous electrolyte battery according to the second embodiment includes the electrode group according to the first embodiment, gas generation can be sufficiently suppressed.
  • a battery pack is provided.
  • This battery pack includes the nonaqueous electrolyte battery according to the second embodiment.
  • the battery pack according to the third embodiment can include one non-aqueous electrolyte battery (unit cell) or can include a plurality of unit cells.
  • each unit cell may be electrically connected in series or in parallel, or may be connected in a combination of series and parallel.
  • FIG. 8 is a block diagram showing an electric circuit of an example battery pack according to the third embodiment.
  • the battery pack 20 shown in FIG. 8 includes a plurality of single cells 21.
  • Each unit cell 21 has the same structure as the nonaqueous electrolyte battery described with reference to FIG.
  • the plurality of single cells 21 are electrically connected to each other in series to form an assembled battery 22.
  • the positive electrode side lead 23 is connected to the positive electrode terminal of the assembled battery 22, and the tip thereof is inserted into the positive electrode side connector 24 and electrically connected thereto.
  • the negative electrode side lead 25 is connected to the negative electrode terminal of the assembled battery 22, and the tip thereof is inserted into the negative electrode side connector 26 and electrically connected thereto.
  • These connectors 24 and 26 are connected to a protection circuit 29 through wires 27 and 28, respectively.
  • the thermistor 30 detects the temperature of the unit cell 21, and the detection signal is transmitted to the protection circuit 29.
  • the protection circuit 29 can cut off the plus side wiring 32a and the minus side wiring 32b between the protection circuit 29 and the terminal 31 for energizing the external device under a predetermined condition.
  • the predetermined condition is, for example, when the temperature detected by the thermistor 30 is equal to or higher than a predetermined temperature.
  • the predetermined condition is when an overcharge, overdischarge, overcurrent, or the like of the unit cell 21 is detected. This detection of overcharge or the like is performed for each individual cell 21 or the entire assembled battery 22.
  • the battery voltage may be detected, or the positive electrode potential or the negative electrode potential may be detected. In the latter case, a lithium electrode used as a reference electrode is inserted into each unit cell 21.
  • the voltage detection wiring 33 is connected to each of the single cells 21, and the detection signal is transmitted to the protection circuit 29 through the wiring 33.
  • FIG. 8 shows a mode in which the unit cells 21 are connected in series, they may be connected in parallel in order to increase the battery capacity.
  • the assembled battery packs can be connected in series and / or in parallel.
  • the mode of the battery pack is appropriately changed depending on the application.
  • those in which cycle characteristics with large current characteristics are desired are preferable.
  • Specific examples include a power source for a digital camera, a vehicle for a two- to four-wheel hybrid electric vehicle, a two- to four-wheel electric vehicle, an assist bicycle, and the like.
  • the vehicle-mounted one is suitable.
  • the battery pack according to the third embodiment described above includes the nonaqueous electrolyte battery according to the second embodiment, gas generation can be sufficiently suppressed.
  • Example 1 In Example 1, the electrode group of Example 1 was produced according to the following procedure.
  • Lithium cobaltate had a composition represented by the formula LiCoO 2.
  • the prepared lithium manganate powder having a spinel crystal structure and the lithium cobaltate powder were mixed at a weight ratio of 80:20 to obtain a mixture powder. This mixture powder was used as a positive electrode active material.
  • NMP N-methylpyrrolidone
  • lithium titanate powder having a spinel crystal structure was prepared.
  • Lithium titanate having a spinel crystal structure had a composition represented by the formula Li 4 Ti 5 O 12 .
  • lithium titanate powder having a spinel crystal structure as a negative electrode active material graphite as a conductive agent, acetylene black as a conductive agent, and PVdF as a binder.
  • a slurry was prepared by adding and mixing with NMP at a weight ratio of 3 wt%: 7 wt%. Subsequently, this slurry was applied to both sides of a current collector made of an aluminum foil having a thickness of 15 ⁇ m so that the coating amount on one side was 30 g / m 2 . Subsequently, the coating film was dried. Next, the dried coating film was pressed. Thus, a negative electrode having a negative electrode material layer having a density (not including a current collector) of 2.1 g / cm 3 was produced.
  • the porous fiber sheet containing the fiber made from a cellulose as a separator was prepared.
  • the average width of the fibers contained in this porous fiber sheet was 33 ⁇ m.
  • the basis weight of this porous fiber sheet was 8 g / m 2 .
  • the porosity of this porous fiber sheet was 18%.
  • the largest pore area was 20 ⁇ 10 ⁇ 9 m 2 .
  • the air permeability of this porous fiber sheet was 0.1 second / 100 ml.
  • the thickness of this porous fiber sheet was 15 ⁇ m.
  • Example 2 to 5 and Comparative Examples 1 to 4 the electrodes of each Example and Comparative Example were prepared in the same procedure as Example 1 except that a porous fiber sheet having the parameters shown in Table 1 below was used. Groups were made.
  • the porous fiber sheet used by each Example and the comparative example contained the fiber made from a cellulose.
  • each porous fiber sheet was produced by adjusting the production conditions described above in a composite manner so that the parameters shown in Table 1 below could be shown.
  • Comparative Example 5 An electrode group of Comparative Example 5 was produced by the same procedure as Example 1 except that the negative electrode was produced by the following procedure.
  • Graphite as a negative electrode active material and PVdF as a binder were added to NMP at a weight ratio of 95% by weight: 5% by weight and mixed to prepare a slurry. Subsequently, this slurry was applied to both sides of a current collector made of an aluminum foil having a thickness of 15 ⁇ m so that the coating amount on one side was 30 g / m 2 . Subsequently, the coating film was dried. Next, the dried coating film was pressed. Thus, a negative electrode having a negative electrode material layer having a density (not including a current collector) of 1.4 g / cm 3 was produced.
  • each nonaqueous electrolyte battery was produced by the following procedure. In the following description, it is described that the “electrode group” is simply used, but each non-aqueous electrolyte battery is manufactured using each electrode group of each example and comparative example in the same manner.
  • the electrode group was housed in an outer can as an outer member.
  • a sealing plate having a liquid injection port was welded to the opening of the outer can. With the liquid injection port opened, the inside of the outer can was subjected to vacuum drying at about 95 ° C. for 8 hours.
  • Ethylene carbonate (EC) and methyl ethyl carbonate (MEC) were mixed at a volume ratio of 1: 2 to prepare a mixed solvent.
  • LiPF 6 lithium hexafluorophosphate
  • the battery unit was charged at a 1C rate for 13 minutes in an environment of 25 ° C. to obtain a SOC of 20%.
  • the battery unit was subjected to aging in a 60 ° C. environment for 90 hours. After the aging was completed, the temporary sealing of the battery unit was released under a reduced pressure environment of ⁇ 90 kPa, and the cells were degassed. Subsequently, this sealing was given to the injection hole. Thus, a nonaqueous electrolyte battery was produced.
  • the nonaqueous electrolyte battery was charged at a constant current at a 1C rate in an environment of 25 ° C., and adjusted to SOC 30%.
  • the thickness Ta [mm] of the nonaqueous electrolyte battery in this state was measured.
  • the thickness T a of the nonaqueous electrolyte battery is, among the dimensions in the three directions orthogonal to each other in a non-aqueous electrolyte battery was the smallest dimension.
  • the nonaqueous electrolyte battery was stored in a 65 ° C. environment for 1 week. Subsequently, the nonaqueous electrolyte battery was taken out from the thermostat. Next, the thickness T b [mm] of the nonaqueous electrolyte battery was measured. Here thickness T b of the was determined by achieving the same dimension as the thickness T a of the previous test.
  • the ratio of the battery thickness T b [mm] after the test to the battery thickness T a [mm] before the test was calculated as a life performance index.
  • the life performance index for each non-aqueous electrolyte battery is shown in Table 2 below.
  • the nonaqueous electrolyte batteries of Examples 1 to 5 exhibited a life performance index lower than that of the nonaqueous electrolyte batteries of Comparative Examples 1, 2, and 4. It means that the smaller the life performance index, the smaller the increase in thickness before and after the test, and the smaller the amount of gas generated. Therefore, it can be said that it is a nonaqueous electrolyte battery in which gas generation can be more sufficiently suppressed as the life performance index is smaller. Therefore, from the results shown in Table 2, the nonaqueous electrolyte batteries of Examples 1 to 5 were able to suppress the gas generation more sufficiently than the nonaqueous electrolyte batteries of Comparative Examples 1, 2, and 4. I understand.
  • Each of the nonaqueous electrolyte batteries of Comparative Examples 3 and 5 could not function as a battery because an electrical short circuit occurred between the positive electrode and the negative electrode.
  • Comparative Example 3 it is considered that an electrical short circuit occurred because the permeability of the separator included in the electrode group was too high.
  • Comparative Example 5 it is considered that lithium dendrite was deposited on the negative electrode due to charge / discharge, which penetrated the porous fiber sheet and caused an electrical short circuit between the positive electrode and the negative electrode.
  • an electrode group includes a positive electrode, a negative electrode, and a separator disposed at least between the positive electrode and the negative electrode.
  • the separator has a permeability of 10% or more and 20% or less.
  • the separator includes a porous fiber sheet including pores having a pore area of 8 ⁇ 10 ⁇ 9 m 2 or more and fibers.
  • This electrode group can promote the movement of fluid in the direction in which the positive electrode and the negative electrode face each other.
  • the negative electrode includes a lithium titanium composite oxide. As a result, this electrode group can realize a non-aqueous electrolyte battery that can sufficiently suppress gas generation.

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Abstract

One embodiment of the present invention provides an electrode group. The electrode group includes a positive electrode, a negative electrode comprising a lithium-titanium composite oxide, and a separator arranged at least between the positive electrode and the negative electrode. The separator comprises fibers. The permeability of the separator is 10-20%. The separator is a porous fiber sheet comprising fibers and pores in which the pore area is 8×10-9 m2 or more.

Description

電極群、非水電解質電池及び電池パックElectrode group, non-aqueous electrolyte battery and battery pack
　本発明の実施形態は、電極群、非水電解質電池及び電池パックに関する。 Embodiments of the present invention relate to an electrode group, a nonaqueous electrolyte battery, and a battery pack.
　従来の鉛蓄電池システムよりも高い入出力特性を発現するシステムの開発が行われている。１つのアプローチとしては、１２Ｖ系の鉛蓄電池と、リチウムイオン二次電池とを並列接続して、蓄電池システムを構築することが挙げられる。このような蓄電システムは、例えば自動車に実装することで、例えば、自動車の制動の際の回生エネルギーの効率的な回収と、アイドリングストップ後のエンジン再始動に必要な大電流放電との実現を期待することができる。 Development of a system that exhibits higher input / output characteristics than conventional lead-acid battery systems has been underway. One approach is to build a storage battery system by connecting a 12V lead storage battery and a lithium ion secondary battery in parallel. By mounting such a power storage system in, for example, an automobile, for example, it is expected to achieve efficient recovery of regenerative energy when braking the automobile and high current discharge necessary for restarting the engine after idling stop. can do.
国際公開第２０１５／１３７１３８号公報International Publication No. 2015/137138 特開２００７－１８８７７７号公報JP 2007-188777 A 国際公開第２０１６／０６８２８６号公報International Publication No. 2016/068286
　ガス発生を十分に抑えることができる非水電解質電池を実現することができる電極群、この電極群を備えた非水電解質電池及びこの非水電解質電池を具備した電池パックを提供することを目的とする。 It is an object to provide an electrode group capable of realizing a nonaqueous electrolyte battery capable of sufficiently suppressing gas generation, a nonaqueous electrolyte battery including the electrode group, and a battery pack including the nonaqueous electrolyte battery. To do.
　第１の実施形態によると、電極群が提供される。この電極群は、正極と、リチウムチタン複合酸化物を含む負極と、少なくとも正極と負極との間に配置されたセパレータとを具備する。セパレータの透地率は、１０％以上２０％以下である。セパレータは、細孔面積が８×１０-9ｍ2以上である細孔と繊維とを含む多孔質繊維シートを含む。 According to a first embodiment, an electrode group is provided. This electrode group includes a positive electrode, a negative electrode including a lithium titanium composite oxide, and a separator disposed at least between the positive electrode and the negative electrode. The permeability of the separator is 10% or more and 20% or less. The separator includes a porous fiber sheet including pores having a pore area of 8 × 10 −9 m 2 or more and fibers.
　第２の実施形態によると、非水電解質電池が提供される。この非水電解質電池は、第１の実施形態に係る電極群と、非水電解質とを具備する。 According to the second embodiment, a nonaqueous electrolyte battery is provided. This nonaqueous electrolyte battery includes the electrode group according to the first embodiment and a nonaqueous electrolyte.
　第３の実施形態によると、電池パックが提供される。この電池パックは、第２の実施形態に係る非水電解質電池を具備する。 According to the third embodiment, a battery pack is provided. This battery pack includes the nonaqueous electrolyte battery according to the second embodiment.
図１は、第１の実施形態に係る一例の電極群の一部展開概略斜視図である。FIG. 1 is a partially developed schematic perspective view of an example electrode group according to the first embodiment. 図２は、図１に示す電極群のＡ部の拡大断面図である。FIG. 2 is an enlarged cross-sectional view of part A of the electrode group shown in FIG. 図３は、第１の実施形態に係る他の例の電極群の概略斜視図である。FIG. 3 is a schematic perspective view of another example electrode group according to the first embodiment. 図４は、図３に示す電極群の線分Ｘ－Ｘに沿った断面図である。4 is a cross-sectional view taken along line XX of the electrode group shown in FIG. 図５は、第１の実施形態に係る他の例の電極群が具備するセパレータの１つのＳＥＭ画像を二値化処理に供して得られた像である。FIG. 5 is an image obtained by subjecting one SEM image of a separator included in another example electrode group according to the first embodiment to a binarization process. 図６は、第１の実施形態に係る一例の電極群が具備するセパレータに含まれる多孔質繊維シートの１つのＳＥＭ画像である。FIG. 6 is an SEM image of a porous fiber sheet included in a separator included in an example electrode group according to the first embodiment. 図７は、第２の実施形態に係る一例の非水電解質電池の分解概略斜視図である。FIG. 7 is an exploded schematic perspective view of an example nonaqueous electrolyte battery according to the second embodiment. 図８は、第３の実施形態に係る一例の電池パックの電気回路を示すブロック図である。FIG. 8 is a block diagram showing an electric circuit of an example battery pack according to the third embodiment.
実施形態Embodiment
　以下に、実施の形態について図面を参照しながら説明する。なお、実施の形態を通して共通の構成には同一の符号を付すものとし、重複する説明は省略する。また、各図は実施の形態の説明とその理解を促すための模式図であり、その形状や寸法、比などは実際の装置と異なる個所があるが、これらは以下の説明と公知の技術とを参酌して、適宜設計変更することができる。 Hereinafter, embodiments will be described with reference to the drawings. In addition, the same code | symbol shall be attached | subjected to a common structure through embodiment, and the overlapping description is abbreviate | omitted. Each figure is a schematic diagram for promoting explanation and understanding of the embodiment, and its shape, dimensions, ratio, etc. are different from the actual device, but these are the following explanations and known techniques. The design can be changed as appropriate.
　（第１の実施形態）
　第１の実施形態によると、電極群が提供される。この電極群は、正極と、リチウムチタン複合酸化物を含む負極と、少なくとも正極と負極との間に配置されたセパレータとを具備する。セパレータの透地率は、１０％以上２０％以下である。セパレータは、細孔面積が８×１０-9ｍ2以上である細孔と繊維とを含む多孔質繊維シートを含む。 (First embodiment)
According to a first embodiment, an electrode group is provided. This electrode group includes a positive electrode, a negative electrode including a lithium titanium composite oxide, and a separator disposed at least between the positive electrode and the negative electrode. The permeability of the separator is 10% or more and 20% or less. The separator includes a porous fiber sheet including pores having a pore area of 8 × 10 −9 m 2 or more and fibers.
　ここで、セパレータの透地率とは、より具体的には、セパレータの主面、例えば正極又は負極に対向していた面を、このセパレータが正極又は負極に対向していた方向、すなわち電極群において正極と負極とが向き合っていた方向から走査型電子顕微鏡（Scanning Electron Microscope：ＳＥＭ）によって観察することによって得られた像（ＳＥＭ像）を以下に詳述する二値化処理に供して得られる像に占める、セパレータの材料、例えば繊維が存在しない部分の面積の割合ということができる。第１の実施形態に係る電極群が具備するセパレータは、この透地率が１０％以上２０％以下であることにより、正極と負極とが向き合った方向に貫通している貫通孔を比較的多く有することができる。 Here, the permeability of the separator is more specifically the main surface of the separator, for example, the surface facing the positive electrode or the negative electrode in the direction in which the separator is facing the positive electrode or the negative electrode, that is, the electrode group. An image (SEM image) obtained by observing with a scanning electron microscope (SEM) from the direction in which the positive electrode and the negative electrode face each other is obtained by subjecting it to a binarization process described in detail below. It can be said that it is the ratio of the area of the portion where no separator material, for example, fibers, occupies the image. The separator included in the electrode group according to the first embodiment has a relatively large number of through holes penetrating in the direction in which the positive electrode and the negative electrode face each other because the permeability is 10% or more and 20% or less. Can have.
　また、第１の実施形態に係る電極群が具備するセパレータは、細孔面積が８×１０-9ｍ2以上である細孔と繊維とを含む多孔質繊維シートを含む。 The separator included in the electrode group according to the first embodiment includes a porous fiber sheet including pores and fibers having a pore area of 8 × 10 −9 m 2 or more.
　透地率が１０％以上２０％以下であり、細孔面積が８×１０-9ｍ2以上である細孔と繊維とを含む多孔質繊維シートを含むセパレータを具備した第１の実施形態に係る電極群は、正極と負極とが向き合った方向における流体の移動を促進することができる。 In the first embodiment, the separator includes a porous fiber sheet including pores and fibers having a permeability of 10% to 20% and a pore area of 8 × 10 −9 m 2 or more. Such an electrode group can promote fluid movement in a direction in which the positive electrode and the negative electrode face each other.
　それにより、第１の実施形態に係る電極群は、ガス発生の要因となる成分を、電極群の何れかの部材に局所的に滞留させずに、セパレータを通して電極群全体に拡散させることができる。例えば、負極が含むリチウムチタン複合酸化物は、水分と反応してガスを発生し得る。第１の実施形態に係る電極群では、負極に水分が含まれていたとしても、この水分の少なくとも一部をセパレータ及び正極へと移動させることができる。ガス発生の要因となる成分が負極に局所的に滞留している場合、電極群からのこの成分の放出は、負極の露出した表面を通してのみとなる。しかしながら、第１の実施形態に係る電極群は、ガス発生の要因となる成分を正極及びセパレータへと拡散させることができるので、この成分を、負極の露出した表面だけでなく、正極及びセパレータのそれぞれの露出した表面を通して放出することもできる。同様に、正極におけるガス発生の要因となる成分が正極に存在している場合、この成分を、正極の露出した表面だけでなく、負極及びセパレータのそれぞれの露出した表面から放出することができる。つまり、第１の実施形態に係る電極群は、ガス発生の要因となる成分の滞留量を十分に低減することができる。 As a result, the electrode group according to the first embodiment can diffuse components that cause gas generation through the separator to the entire electrode group without locally staying in any member of the electrode group. . For example, lithium titanium composite oxide included in the negative electrode can react with moisture to generate gas. In the electrode group according to the first embodiment, even if moisture is contained in the negative electrode, at least a part of this moisture can be moved to the separator and the positive electrode. When a component that causes gas generation is locally retained in the negative electrode, the release of this component from the electrode group is only through the exposed surface of the negative electrode. However, since the electrode group according to the first embodiment can diffuse components that cause gas generation into the positive electrode and the separator, this component can be used not only for the exposed surface of the negative electrode but also for the positive electrode and the separator. It can also be released through each exposed surface. Similarly, when a component that causes gas generation in the positive electrode is present in the positive electrode, this component can be released not only from the exposed surface of the positive electrode but also from the exposed surfaces of the negative electrode and the separator. That is, the electrode group according to the first embodiment can sufficiently reduce the retention amount of components that cause gas generation.
　第１の実施形態に係る電極群は、以上に説明した作用を、非水電解質電池に組み込まれた状態においても発現することができる。 The electrode group according to the first embodiment can exhibit the above-described action even in a state where the electrode group is incorporated in a nonaqueous electrolyte battery.
　そして、負極が含むリチウムチタン複合酸化物は、Ｌｉが挿入されていない状態では、電気的絶縁性を示すことができる。第１の実施形態に係る電極群が具備するセパレータは先に説明したように正極と負極とが向き合った方向に貫通している貫通孔を比較的多く有することができるが、万が一この貫通孔を介して正極と負極とが接触しても、負極の接触部分においてすぐさまリチウムチタン複合酸化物からＬｉが脱離される。それにより、負極の接触部分は、絶縁状態となり、更なる通電を防ぐことができる。 The lithium-titanium composite oxide included in the negative electrode can exhibit electrical insulation in a state where Li is not inserted. The separator included in the electrode group according to the first embodiment can have a relatively large number of through holes penetrating in the direction in which the positive electrode and the negative electrode face each other as described above. Even if the positive electrode and the negative electrode come into contact with each other, Li is immediately released from the lithium titanium composite oxide at the contact portion of the negative electrode. Thereby, the contact part of a negative electrode will be in an insulating state, and can prevent further electricity supply.
　更に、リチウムチタン複合酸化物は、リチウムの酸化還元電位に対して十分に高い、リチウムの吸蔵及び放出電位（作動電位）を示すことができる。そのため、第１の実施形態に係る電極群を具備する非水電解質電池を急速充放電に繰り返し供しても、負極上にリチウムデンドライトが析出するのを防ぐことができる。正極と負極とが向き合った方向に貫通している貫通孔を比較的多く有するセパレータを含んだ電極群においてリチウムデンドライトが生じると、リチウムデンドライトが貫通孔に沿って成長し、正極と負極との導電経路となり得、電気的短絡を発生させ得る。第１の実施形態に係る電極群は、リチウムデンドライトによるこのような電気的短絡が発生するのを防ぐことができる。従って、第１の実施形態に係る電極は、実際に機能することができる非水電解質電池を提供することができる。 Furthermore, the lithium-titanium composite oxide can exhibit a lithium occlusion and release potential (operating potential) that is sufficiently higher than the oxidation-reduction potential of lithium. Therefore, even if the nonaqueous electrolyte battery including the electrode group according to the first embodiment is repeatedly subjected to rapid charge / discharge, it is possible to prevent lithium dendrite from being deposited on the negative electrode. When lithium dendrite occurs in an electrode group including a separator having a relatively large number of through holes penetrating in the direction in which the positive electrode and the negative electrode face each other, the lithium dendrite grows along the through holes, and the conductivity between the positive electrode and the negative electrode is increased. It can be a path and an electrical short can occur. The electrode group according to the first embodiment can prevent the occurrence of such an electrical short circuit due to the lithium dendrite. Therefore, the electrode according to the first embodiment can provide a nonaqueous electrolyte battery that can actually function.
　以上の理由により、第１の実施形態に係る電極群は、ガス発生を十分に抑えることができる非水電解質電池を実現することができる。 For the above reasons, the electrode group according to the first embodiment can realize a nonaqueous electrolyte battery that can sufficiently suppress gas generation.
　また、非水電解質電池におけるガスの発生量を抑制することにより、非水電解質電池の寿命性能を向上させることができる。よって、第１の実施形態に係る電極群は、優れた寿命性能を示すことができる非水電解質電池を実現することもできる。 In addition, the life performance of the nonaqueous electrolyte battery can be improved by suppressing the amount of gas generated in the nonaqueous electrolyte battery. Therefore, the electrode group according to the first embodiment can also realize a nonaqueous electrolyte battery capable of exhibiting excellent life performance.
　第１の実施形態に係る電極群を、以下に、より詳細に説明する。　
　第１の実施形態に係る電極群は、正極と、負極と、セパレータとを具備する。　
　正極は、例えば、正極集電体と、正極材料層とを具備することができる。正極集電体は、例えば、帯状の平面形状を有することができる。正極材料層は、正極集電体の両方の表面又は片方の表面に配置することができる。正極集電体は、正極材料層を何れの表面にも担持していない部分を含むこともできる。この部分は、正極集電タブとして働くこともできる。或いは、正極は、正極集電体とは別体の正極集電タブを含むこともできる。 The electrode group according to the first embodiment will be described in more detail below.
The electrode group according to the first embodiment includes a positive electrode, a negative electrode, and a separator.
The positive electrode can include, for example, a positive electrode current collector and a positive electrode material layer. The positive electrode current collector can have, for example, a belt-like planar shape. The positive electrode material layer can be disposed on both surfaces or one surface of the positive electrode current collector. The positive electrode current collector can also include a portion that does not carry the positive electrode material layer on any surface. This part can also serve as a positive electrode current collecting tab. Alternatively, the positive electrode may include a positive electrode current collecting tab that is separate from the positive electrode current collector.
　正極材料層は、正極活物質を含むことができる。正極材料層は、必要に応じて、導電剤及び結着剤を更に含むこともできる。 The positive electrode material layer can contain a positive electrode active material. The positive electrode material layer can further contain a conductive agent and a binder as necessary.
　負極は、例えば、負極集電体と、負極材料層とを具備することができる。負極集電体は、例えば、帯状の平面形状を有することができる。負極材料層は、負極集電体の両方の表面又は片方の表面に配置することができる。負極集電体は、負極材料層を何れの表面にも担持していない部分を含むこともできる。この部分は、負極集電タブとして働くこともできる。 The negative electrode can include, for example, a negative electrode current collector and a negative electrode material layer. The negative electrode current collector can have, for example, a belt-like planar shape. The negative electrode material layer can be disposed on both surfaces or one surface of the negative electrode current collector. The negative electrode current collector can also include a portion that does not carry the negative electrode material layer on any surface. This part can also serve as a negative electrode current collecting tab.
　負極材料層は、負極活物質を含むことができる。負極材料層は、必要に応じて、導電剤及び結着剤を更に含むこともできる。 The negative electrode material layer can contain a negative electrode active material. The negative electrode material layer can further contain a conductive agent and a binder as necessary.
　リチウムチタン複合酸化物は、例えば、負極活物質として負極材料層に含まれ得る。負極活物質は、リチウムチタン複合酸化物からなっていてもよいし、又はリチウムチタン複合酸化物と他の負極活物質との混合物であってもよい。負極活物質は、リチウムチタン複合酸化物を５０重量％以上含むことが好ましく、８０重量％以上含むことがより好ましく、リチウムチタン複合酸化物からなることが最も好ましい。 The lithium titanium composite oxide can be contained in the negative electrode material layer as a negative electrode active material, for example. The negative electrode active material may be made of a lithium titanium composite oxide, or may be a mixture of a lithium titanium composite oxide and another negative electrode active material. The negative electrode active material preferably contains 50% by weight or more of lithium titanium composite oxide, more preferably contains 80% by weight or more, and most preferably consists of lithium titanium composite oxide.
　リチウムチタン複合酸化物を含まない負極と第１の実施形態に係る電極群が具備するセパレータとを組み合わせて用いて作製した電極群は、セパレータの貫通孔を介して正極と負極とが接触すると電気が流れ続ける場合がある。このような電極群は、実際に機能する電池を実現することができない場合がある。 An electrode group produced using a combination of a negative electrode that does not include a lithium titanium composite oxide and the separator included in the electrode group according to the first embodiment is electrically connected to the positive electrode and the negative electrode through the through hole of the separator. May continue to flow. Such an electrode group may not realize a battery that actually functions.
　セパレータは、少なくとも正極と負極との間に配置される。例えば、正極材料層と負極材料層とは、セパレータを介して向き合うことができる。多孔質繊維シートは、正極と負極との間以外にも存在していてもよい。例えば、電極群と他の部材との通電を防ぐ目的で、電極群の最外層に、多孔質繊維シートの一部が配置されていてもよい。 The separator is disposed at least between the positive electrode and the negative electrode. For example, the positive electrode material layer and the negative electrode material layer can face each other via a separator. The porous fiber sheet may exist other than between the positive electrode and the negative electrode. For example, a part of the porous fiber sheet may be disposed in the outermost layer of the electrode group for the purpose of preventing energization between the electrode group and other members.
　セパレータは、透地率が１０％以上２０％以下である。セパレータは、細孔面積が８×１０-9ｍ2以上である細孔と繊維とを含む多孔質繊維シートを含む。 The separator has a permeability of 10% or more and 20% or less. The separator includes a porous fiber sheet including pores having a pore area of 8 × 10 −9 m 2 or more and fibers.
　セパレータの透地率が１０％未満である電極群は、正極と負極とが対向した方向における流体の移動を十分に促進することができない。また、セパレータの透地率が２０％を超える電極群は、正極と負極との間の十分な絶縁性を発揮することが困難であり、実際に使用できる非水電解質電池を提供することができない。 The electrode group in which the permeability of the separator is less than 10% cannot sufficiently promote the movement of fluid in the direction in which the positive electrode and the negative electrode face each other. Moreover, it is difficult for the electrode group in which the permeability of the separator exceeds 20% to exhibit sufficient insulation between the positive electrode and the negative electrode, and it is not possible to provide a practically usable nonaqueous electrolyte battery. .
　また、セパレータの透地率が１０％以上２０％以下であっても、多孔質繊維シートが８×１０-9ｍ2以上である細孔面積を有する細孔を含まない電極群では、正極と負極とが向き合った方向における流体の移動を十分に促進することができない。 Further, even when the permeability of the separator is 10% or more and 20% or less, in the electrode group that does not include pores in which the porous fiber sheet has a pore area of 8 × 10 −9 m 2 or more, The movement of the fluid in the direction facing the negative electrode cannot be sufficiently promoted.
　セパレータの透地率は、１２％以上１８％以下であることが好ましく、１５％以上１８％以下であることがより好ましい。また、多孔質繊維シートは、８．５×１０-9ｍ2以上である細孔面積を有する細孔を含むことが好ましく、１０×１０-9ｍ2以上である細孔面積を有する細孔を含むことがより好ましい。また、多孔質繊維シートは、例えば、２５×１０-9ｍ2以下である細孔面積を有する細孔を含むことができ、２０×１０-9ｍ2以下である細孔面積を有する細孔を含むことがより好ましい。 The permeability of the separator is preferably 12% or more and 18% or less, and more preferably 15% or more and 18% or less. The porous fiber sheet preferably includes pores having a pore area of 8.5 × 10 −9 m 2 or more, and pores having a pore area of 10 × 10 −9 m 2 or more. It is more preferable to contain. The porous fiber sheet can include, for example, pores having a pore area of 25 × 10 −9 m 2 or less, and pores having a pore area of 20 × 10 −9 m 2 or less. It is more preferable to contain.
　また、多孔質繊維シートが含む繊維は、平均幅が１０μｍ以上４０μｍ以下であることが好ましい。この好ましい態様の電極群が具備するセパレータは、非水電解質の優れた保持性を示すことができる。その結果、この好ましい態様の電極群を具備した非水電解質電池では、電荷担体、例えばＬｉイオンを、多孔質繊維シートに保持された非水電解質を介して正極と負極との間で円滑に移動させることができ、電荷担体の移動による電極群の各部材への負荷を小さくすることができる。従って、この好ましい態様の電極群は、より優れた寿命性能を示すことができる非水電解質電池を実現することができる。繊維の平均幅は、１０μｍ以上３０μｍ以下であることがより好ましい。 Further, the fibers included in the porous fiber sheet preferably have an average width of 10 μm or more and 40 μm or less. The separator included in the electrode group of this preferred embodiment can exhibit excellent retainability of the nonaqueous electrolyte. As a result, in the non-aqueous electrolyte battery including the electrode group of this preferred embodiment, the charge carrier, for example, Li ions can be smoothly moved between the positive electrode and the negative electrode through the non-aqueous electrolyte held in the porous fiber sheet. The load on each member of the electrode group due to the movement of the charge carriers can be reduced. Therefore, the electrode group of this preferred embodiment can realize a non-aqueous electrolyte battery that can exhibit better life performance. The average width of the fibers is more preferably 10 μm or more and 30 μm or less.
　ここで、繊維の平均幅は、セパレータが正極又は負極に対向していた方向から多孔質繊維シートを走査型電子顕微鏡によって観察して得られた像から測定することができる。繊維の平均幅の測定方法は、以下に詳述する。 Here, the average width of the fibers can be measured from an image obtained by observing the porous fiber sheet with a scanning electron microscope from the direction in which the separator faces the positive electrode or the negative electrode. The method for measuring the average width of the fibers will be described in detail below.
　多孔質繊維シートの坪量は、５ｇ／ｍ2以上２０ｇ／ｍ2以下であることが好ましく、８ｇ／ｍ2以上１５ｇ／ｍ2以下であることがより好ましい。 The basis weight of the porous fiber sheet is preferably 5 g / m 2 or more and 20 g / m 2 or less, and more preferably 8 g / m 2 or more and 15 g / m 2 or less.
　多孔質繊維シートは、直径が５０μｍ以上である細孔を含むことが好ましく、直径が８０μｍ以上である細孔を含むことがより好ましい。多孔質繊維シートが含む細孔は、直径が３００μｍ以下であることが好ましく、直径が２００μｍ以下であることがより好ましい。 The porous fiber sheet preferably includes pores having a diameter of 50 μm or more, and more preferably includes pores having a diameter of 80 μm or more. The pores contained in the porous fiber sheet preferably have a diameter of 300 μm or less, and more preferably have a diameter of 200 μm or less.
　また、多孔質繊維シートは、０．１秒／１００ｍｌ以上１秒／１００ｍｌ以下であるガーレー法に基づく透気度を示すことができる。ここで、ガーレー法に基づく透気度は、ＪＩＳ　Ｃ２３００で規定された方法によって測定することができる。多孔質繊維シートは、０．１秒／１００ｍｌ以上０．５秒／１００ｍｌ以下であるガーレー法に基づく透気度を示すことが望ましい。 Further, the porous fiber sheet can exhibit an air permeability based on the Gurley method of 0.1 second / 100 ml or more and 1 second / 100 ml or less. Here, the air permeability based on the Gurley method can be measured by a method defined in JIS C2300. The porous fiber sheet desirably exhibits air permeability based on the Gurley method of 0.1 second / 100 ml or more and 0.5 second / 100 ml or less.
　正極材料層及び負極材料層は、例えば多孔質であり得る。１つの態様に係る電極群では、正極は多孔質の正極材料層を具備し、負極は負極材料層を具備する。負極材料層は、リチウムチタン複合酸化物を含むことができる。セパレータは、少なくとも正極材料層と負極材料層との間に配置されることができる。この態様の電極群では、セパレータを通して移動した流体を、正極材料層、セパレータ及び負極材料層のそれぞれの露出した表面からより円滑に放出することができ、それにより、ガス発生の原因となる成分の電極群における滞留量をより減らすことができる。 The positive electrode material layer and the negative electrode material layer may be porous, for example. In the electrode group according to one aspect, the positive electrode includes a porous positive electrode material layer, and the negative electrode includes a negative electrode material layer. The negative electrode material layer can include a lithium titanium composite oxide. The separator can be disposed at least between the positive electrode material layer and the negative electrode material layer. In the electrode group according to this aspect, the fluid that has moved through the separator can be more smoothly discharged from the exposed surfaces of the positive electrode material layer, the separator, and the negative electrode material layer, so that the components that cause gas generation can be discharged. The amount of residence in the electrode group can be further reduced.
　第１の実施形態に係る電極群は、様々な構造を有することができる。例えば、電極群は、巻回型の構造を有することができる。巻回型の構造を有する電極群は、例えば、扁平形状又は円筒形状を有することができる。巻回型の電極群は、例えば、以下の手順で作製することができる。まず、一枚のセパレータと、正極と、もう一枚のセパレータと、負極とをこの順で積層させて積層体を作る。次いで、この積層体を例えば負極が外側に位置するように巻回する。巻芯を抜き取ることにより、円筒形状の巻回型電極群が得られる。例えば、この円筒形状の電極群をプレスに供することにより、扁平形状の巻回型電極群が得られる。或いは、電極群は、積層型の構造を有することができる。積層型の構造を有する電極群は、例えば、正極と負極とを、これらの間にセパレータが挟まれるように、交互に積層することによって得られる。第１の実施形態に係る電極群は、巻回型及び積層型の構造以外の構造を有することもできる。 The electrode group according to the first embodiment can have various structures. For example, the electrode group can have a wound structure. The electrode group having a wound structure can have, for example, a flat shape or a cylindrical shape. The wound electrode group can be produced, for example, by the following procedure. First, a separator is made by laminating one separator, a positive electrode, another separator, and a negative electrode in this order. Next, this laminate is wound, for example, so that the negative electrode is positioned outside. By extracting the winding core, a cylindrical wound electrode group can be obtained. For example, a flat wound electrode group can be obtained by subjecting this cylindrical electrode group to pressing. Alternatively, the electrode group may have a stacked structure. The electrode group having a stacked structure is obtained, for example, by alternately stacking a positive electrode and a negative electrode so that a separator is sandwiched between them. The electrode group according to the first embodiment may have a structure other than a wound type and a stacked type structure.
　次に、第１の実施形態に係る電極群で用いることができる材料をより詳細に説明する。 Next, materials that can be used in the electrode group according to the first embodiment will be described in more detail.
　１）負極
　負極集電体には、例えば金属箔又は合金箔が用いられる。集電体の厚さは、２０μｍ以下、より好ましくは１５μｍ以下であることが望ましい。金属箔としては、銅箔、アルミニウム箔といったものが挙げられる。アルミニウム箔を用いる場合、アルミニウム箔の純度は、９９重量％以上であることが好ましい。合金箔としては、ステンレス鋼箔、アルミニウム合金箔といったものが挙げられる。アルミニウム合金箔中のアルミニウム合金は、マグネシウム、亜鉛及びケイ素よりなる群から選ばれる少なくとも１種類の元素を含むことが好ましい。合金成分中の鉄、銅、ニッケル、クロムなどの遷移金属の含有量は１重量％以下にすることが好ましい。 1) Negative electrode For the negative electrode current collector, for example, a metal foil or an alloy foil is used. The thickness of the current collector is desirably 20 μm or less, more preferably 15 μm or less. Examples of the metal foil include copper foil and aluminum foil. When using aluminum foil, it is preferable that the purity of aluminum foil is 99 weight% or more. Examples of the alloy foil include stainless steel foil and aluminum alloy foil. The aluminum alloy in the aluminum alloy foil preferably contains at least one element selected from the group consisting of magnesium, zinc and silicon. The content of transition metals such as iron, copper, nickel and chromium in the alloy components is preferably 1% by weight or less.
　リチウムチタン複合酸化物としては、例えば、スピネル型の結晶構造を有するリチウムチタン複合酸化物が挙げられる。スピネル型の結晶構造を有するリチウムチタン複合酸化物としては、Ｌｉ4+xＴｉ5Ｏ12（ｘは充放電反応により０≦ｘ≦３の範囲で変化する）で表される組成を有するチタン酸リチウムを挙げることができる。リチウムチタン複合酸化物の他の例としては、ラムスデライト型の結晶構造を有するリチウムチタン複合酸化物が挙げられる。ラムスデライト型のチタン含有酸化物の例として、Ｌｉ2+yＴｉ3Ｏ7（ｙは充放電反応により－１≦ｙ≦３の範囲で変化する）で表される組成を有する複合酸化物が挙げられる。 Examples of the lithium titanium composite oxide include a lithium titanium composite oxide having a spinel crystal structure. As a lithium titanium composite oxide having a spinel crystal structure, titanic acid having a composition represented by Li 4 + x Ti 5 O 12 (x varies in the range of 0 ≦ x ≦ 3 by charge / discharge reaction) Lithium can be mentioned. Another example of the lithium titanium composite oxide is a lithium titanium composite oxide having a ramsdellite type crystal structure. As an example of a ramsdellite-type titanium-containing oxide, a composite oxide having a composition represented by Li 2 + y Ti 3 O 7 (y changes in the range of −1 ≦ y ≦ 3 by charge / discharge reaction) is given. Can be mentioned.
　リチウムチタン複合酸化物以外の負極活物質の例としては、リチウムを吸蔵放出可能な炭素質物（例えば、グラファイト、ハードカーボン、ソフトカーボン、グラフェン）、リチウムチタン複合酸化物以外のチタン含有酸化物、硫化物、窒化物、例えばＳｎＢ0.4Ｐ0.6Ｏ3.1などのアモルファス状のスズ複合酸化物、例えばＳｎＳｉＯ3などのスズ珪素複合酸化物、例えばＳｉＯなどの酸化珪素、チタン含有酸化物以外の金属酸化物（例えばＷＯ3などのタングステン酸化物）といったものが挙げられる。リチウムチタン複合酸化物以外の負極活物質としては、上記負極活物質のうちの１種類、又は２種類以上の混合物を用いることができる。 Examples of negative electrode active materials other than lithium-titanium composite oxides include carbonaceous materials capable of occluding and releasing lithium (eg, graphite, hard carbon, soft carbon, graphene), titanium-containing oxides other than lithium-titanium composite oxides, sulfides things, nitrides such SnB 0.4 P 0.6 O 3.1 amorphous tin composite oxide such as, for example, tin silicon composite oxides such as SnSiO 3, for example, silicon oxides such as SiO, a metal oxide other than the titanium-containing oxide ( For example, a tungsten oxide such as WO 3 ). As the negative electrode active material other than the lithium titanium composite oxide, one kind or a mixture of two or more kinds of the above negative electrode active materials can be used.
　硫化物、窒化物、アモルファス状のスズ複合酸化物、スズ珪素複合酸化物及び金属酸化物には、例えば、合成時にリチウムを含む化合物、及び合成時にはリチウムを含まない化合物が含まれる。また、チタン含有酸化物の中にも、合成時にはリチウムを含まないものもある（例えば、単斜晶型の結晶構造を有する二酸化チタン、斜方晶型の結晶構造を有するニオブチタン複合酸化物など）。合成時にリチウムを含まない負極活物質は、例えば充電によりリチウムを含むことができる。 The sulfide, nitride, amorphous tin composite oxide, tin silicon composite oxide and metal oxide include, for example, a compound containing lithium at the time of synthesis and a compound not containing lithium at the time of synthesis. Further, some titanium-containing oxides do not contain lithium during synthesis (for example, titanium dioxide having a monoclinic crystal structure, niobium titanium composite oxide having an orthorhombic crystal structure, etc.). . The negative electrode active material not containing lithium at the time of synthesis can contain lithium, for example, by charging.
　リチウムチタン複合酸化物以外のチタン含有酸化物の例には、例えば、アナターゼ型の結晶構造を有するチタン含有酸化物、ルチル型の結晶構造を有するチタン含有酸化物、ブロンズ型又は単斜晶型の結晶構造を有するチタン含有酸化物、並びにＴｉとＰ、Ｖ、Ｓｎ、Ｃｕ、Ｎｉ、Ｎｂ及びＦｅよりなる群から選択される少なくとも１種類の元素とを含有する金属複合酸化物が含まれる。 Examples of titanium-containing oxides other than lithium-titanium composite oxide include, for example, titanium-containing oxides having anatase type crystal structure, titanium-containing oxides having rutile type crystal structure, bronze type or monoclinic type A titanium-containing oxide having a crystal structure and a metal composite oxide containing Ti and at least one element selected from the group consisting of P, V, Sn, Cu, Ni, Nb, and Fe are included.
　ＴｉとＰ、Ｖ、Ｓｎ、Ｃｕ、Ｎｉ、Ｎｂ及びＦｅよりなる群から選択される少なくとも１種類の元素とを含有する金属複合酸化物としては、例えば、ＴｉＯ2－Ｐ2Ｏ5、ＴｉＯ2－Ｖ2Ｏ5、ＴｉＯ2-Ｐ2Ｏ5－ＳｎＯ2、ＴｉＯ2－Ｐ2Ｏ5－ＭｅＯ（Ｍｅは、Ｃｕ、Ｎｉ及びＦｅよりなる群から選択される少なくとも１種類の元素である）、ニオブチタン複合酸化物（例えば、Ｎｂ2ＴｉＯ7など）などを挙げることができる。この金属複合酸化物は、結晶性が低く、結晶相とアモルファス相とが共存している構造を有するか、又はアモルファス相単独で存在したミクロ構造を有することが好ましい。このようなミクロ構造であることによりサイクル性能を大幅に向上させることができる。 Examples of the metal composite oxide containing Ti and at least one element selected from the group consisting of P, V, Sn, Cu, Ni, Nb, and Fe include TiO 2 —P 2 O 5 , TiO 2. —V 2 O 5 , TiO 2 —P 2 O 5 —SnO 2 , TiO 2 —P 2 O 5 —MeO (Me is at least one element selected from the group consisting of Cu, Ni and Fe) And niobium titanium composite oxide (eg, Nb 2 TiO 7 ). This metal complex oxide preferably has a low crystallinity and has a structure in which a crystalline phase and an amorphous phase coexist, or a microstructure in which an amorphous phase exists alone. With such a microstructure, cycle performance can be greatly improved.
　アナターゼ型、ルチル型又はブロンズ型（すなわち、単斜晶型）の結晶構造を有するチタン含有酸化物の組成は、ＴｉＯ2で表すことができる。 The composition of the titanium-containing oxide having an anatase type, rutile type or bronze type (ie, monoclinic type) crystal structure can be represented by TiO 2 .
　硫化物としては、例えばＴｉＳ2などの硫化チタン、例えばＭｏＳ2などの硫化モリブデン、例えば、ＦｅＳ、ＦｅＳ2、ＬｉxＦｅＳ2（０≦ｘ≦２）などの硫化鉄などが例えば挙げられる。 Examples of the sulfide include titanium sulfide such as TiS 2 , molybdenum sulfide such as MoS 2, and iron sulfide such as FeS, FeS 2 , and Li x FeS 2 (0 ≦ x ≦ 2).
　窒化物としては、例えば、リチウムコバルト窒化物（例えば、ＬｉxＣｏyＮ、ここで、０＜ｘ＜４であり、０＜ｙ＜０．５である）などが挙げられる。 Examples of the nitride include lithium cobalt nitride (for example, Li x Co y N, where 0 <x <4 and 0 <y <0.5).
　導電剤としては、例えば炭素含有材料（アセチレンブラック、ケッチェンブラック、黒鉛等）、及び金属粉末を挙げることができる。 Examples of the conductive agent include carbon-containing materials (acetylene black, ketjen black, graphite, etc.) and metal powder.
　結着剤としては、例えばポリテトラフルオロエチレン(ＰＴＦＥ)、ポリフッ化ビニリデン(ＰＶｄＦ)、フッ素系ゴム及びスチレンブタジエンゴムなどが挙げられる。 Examples of the binder include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), fluorine rubber, and styrene butadiene rubber.
　負極材料層の目付量は、１０ｇ／ｍ2以上３００ｇ／ｍ2以下の範囲にすることが望ましい。さらに好ましい範囲は、２０ｇ／ｍ2以上２００ｇ／ｍ2以下である。 The basis weight of the negative electrode material layer is desirably in the range of 10 g / m 2 to 300 g / m 2 . A more preferable range is 20 g / m 2 or more and 200 g / m 2 or less.
　負極材料層の密度は、１．５ｇ／ｃｍ3以上３．２ｇ／ｃｍ3以下の範囲にすることが望ましい。さらに好ましい範囲は、１．８ｇ／ｃｍ3以上２．５ｇ／ｃｍ3以下である。 The density of the negative electrode material layer is desirably in the range of 1.5 g / cm 3 or more and 3.2 g / cm 3 or less. A more preferable range is 1.8 g / cm 3 or more and 2.5 g / cm 3 or less.
　負極は、例えば、以下の手順で作製することができる。まず、粉末状の負極活物質に導電剤及び結着剤を添加し、これらを適当な溶媒に懸濁させて、懸濁物（スラリー）を得る。次いで、この懸濁物を帯状の集電体の両面又は片面に塗布し、塗膜を乾燥させる。この際、集電体の一部に、懸濁物未塗布部を残してもよい。次いで、塗膜をプレスして帯状電極にすることにより、負極を得ることができる。 The negative electrode can be produced, for example, by the following procedure. First, a conductive agent and a binder are added to a powdered negative electrode active material, and these are suspended in an appropriate solvent to obtain a suspension (slurry). Next, this suspension is applied to both sides or one side of a belt-like current collector, and the coating film is dried. At this time, the suspension uncoated portion may be left in a part of the current collector. Subsequently, a negative electrode can be obtained by pressing a coating film into a strip electrode.
　負極活物質、導電剤及び結着剤の配合比は、負極活物質７３～９８重量％、導電剤０～２０重量％、結着剤２～７重量％の範囲にすることが好ましい。 The compounding ratio of the negative electrode active material, the conductive agent and the binder is preferably in the range of 73 to 98% by weight of the negative electrode active material, 0 to 20% by weight of the conductive agent, and 2 to 7% by weight of the binder.
　２）正極
　正極集電体は、アルミニウム箔又はアルミニウム合金箔から形成されることが望ましい。アルミニウム箔の純度は９９重量％以上であることが好ましい。アルミニウム合金としては、マグネシウム、亜鉛及びケイ素よりなる群から選択される１種類以上の元素を含む合金が好ましい。一方、鉄、銅、ニッケル、クロムなどの遷移金属の含有量は１重量％以下にすることが好ましい。 2) Positive electrode The positive electrode current collector is preferably formed from an aluminum foil or an aluminum alloy foil. The purity of the aluminum foil is preferably 99% by weight or more. As the aluminum alloy, an alloy containing one or more elements selected from the group consisting of magnesium, zinc and silicon is preferable. On the other hand, the content of transition metals such as iron, copper, nickel and chromium is preferably 1% by weight or less.
　正極集電体の厚さは、２０μｍ以下であることが好ましく、より好ましくは１５μｍ以下である。 The thickness of the positive electrode current collector is preferably 20 μm or less, more preferably 15 μm or less.
　正極活物質の例としては、種々の酸化物及び硫化物などが挙げられる。例えば、二酸化マンガン（ＭｎＯ2）、酸化鉄、酸化銅、酸化ニッケル、リチウムマンガン複合酸化物（例えば、ＬｉxＭｎ2Ｏ4（０≦ｘ≦１）、又はＬｉxＭｎＯ2（０≦ｘ≦１））、リチウムニッケル複合酸化物（例えばＬｉxＮｉＯ2（０≦ｘ≦１））、リチウムコバルト複合酸化物（例えばＬｉxＣｏＯ2（０≦ｘ≦１））、リチウムニッケルコバルト複合酸化物（例えばＬｉxＮｉ1-y-zＣｏyＭzＯ2（ＭはＡｌ、Ｃｒ及びＦｅからなる群より選択される少なくとも１種類の元素であり、０≦ｘ≦１、０≦ｙ≦０．５、０≦ｚ≦０．１である））、リチウムマンガンコバルト複合酸化物（例えばＬｉxＭｎ1-ｙ-ｚＣｏyＭzＯ2（ＭはＡｌ、Ｃｒ及びＦｅからなる群より選択される少なくとも１種類の元素であり、０≦ｘ≦１、０≦ｙ≦０．５、０≦ｚ≦０．１である））、リチウムマンガンニッケル複合化合物（例えばＬｉxＭｎ1/2Ｎｉ1/2Ｏ2（０≦ｘ≦１））、スピネル型の結晶構造を有するリチウムマンガンニッケル複合酸化物（例えばＬｉxＭｎ2-yＮｉyＯ4（０≦ｘ≦１、０≦ｙ≦１））、オリビン型の結晶構造を有するリチウムリン酸化物（例えば、ＬｉxＦｅＰＯ4（０≦ｘ≦１）、ＬｉxＦｅ1-yＭｎyＰＯ4（０≦ｙ≦１）、ＬｉxＣｏＰＯ4（０≦ｘ≦１）など）、硫酸鉄（例えばＦｅ2（ＳＯ4）3）、バナジウム酸化物（例えばＶ2Ｏ5）、及び一般式ＬｉxＮｉ1-a-bＣｏaＭｎbＭcＯ2（０．９＜ｘ≦１．２５、０＜ａ≦０．４、０≦ｂ≦０．４５、０≦ｃ≦０．１、ＭはＭｇ、Ａｌ、Ｓｉ、Ｔｉ、Ｚｎ、Ｚｒ、Ｃａ及びＳｎからなる群より選ばれる少なくとも１種の元素を表す）で表される組成を有する化合物などが挙げられる。また、ポリアニリンやポリピロールなどの導電性ポリマー材料、ジスルフィド系ポリマー材料、イオウ（Ｓ）、フッ化カーボンなどの有機材料及び無機材料も挙げられる。 Examples of the positive electrode active material include various oxides and sulfides. For example, manganese dioxide (MnO 2), iron oxide, copper oxide, nickel oxide, lithium-manganese composite oxide (e.g., Li x Mn 2 O 4 ( 0 ≦ x ≦ 1), or Li x MnO 2 (0 ≦ x ≦ 1)), lithium nickel composite oxide (for example, Li x NiO 2 (0 ≦ x ≦ 1)), lithium cobalt composite oxide (for example, Li x CoO 2 (0 ≦ x ≦ 1)), lithium nickel cobalt composite oxide (For example, Li x Ni 1 -yz Co y M z O 2 (M is at least one element selected from the group consisting of Al, Cr and Fe, and 0 ≦ x ≦ 1, 0 ≦ y ≦ 0.5) , 0 ≦ z ≦ 0.1)), lithium manganese cobalt composite oxide (for example, Li x Mn 1-yz Co y M z O 2 (M is selected from the group consisting of Al, Cr and Fe) At least one element, 0 ≦ x ≦ 1 0 ≦ y ≦ 0.5, 0 a ≦ z ≦ 0.1)), lithium manganese nickel complex compound (e.g. Li x Mn 1/2 Ni 1/2 O 2 (0 ≦ x ≦ 1)), spinel Lithium manganese nickel composite oxide having a crystal structure of (for example, Li x Mn 2 -y Ni y O 4 (0 ≦ x ≦ 1, 0 ≦ y ≦ 1)), lithium phosphorus oxide having an olivine type crystal structure ( For example, Li x FePO 4 (0 ≦ x ≦ 1), Li x Fe 1-y Mn y PO 4 (0 ≦ y ≦ 1), Li x CoPO 4 (0 ≦ x ≦ 1) , etc.), iron sulfate (e.g. Fe 2 (SO 4) 3) , vanadium oxide (e.g. V 2 O 5), and the general formula Li x Ni 1-ab Co a Mn b M c O 2 (0.9 <x ≦ 1.25,0 < a ≦ 0.4, 0 ≦ b ≦ 0.45, 0 ≦ c ≦ 0.1, M is composed of Mg, Al, Si, Ti, Zn, Zr, Ca and Sn. And compounds having a composition represented by represents at least one element selected from the group) can be mentioned. In addition, conductive polymer materials such as polyaniline and polypyrrole, disulfide-based polymer materials, organic materials such as sulfur (S) and carbon fluoride, and inorganic materials are also included.
　正極活物質の種類は、１種類又は２種類以上にすることができる。 The type of positive electrode active material can be one type or two or more types.
　導電剤としては、例えばカーボンブラック、黒鉛（グラファイト）、グラフェン、フラーレン類、コークス等を挙げることができる。中でもカーボンブラック、黒鉛が好ましい。カーボンブラックとしては、アセチレンブラック、ケッチェンブラック、ファーネスブラック等が挙げられる。 Examples of the conductive agent include carbon black, graphite (graphite), graphene, fullerenes, coke and the like. Of these, carbon black and graphite are preferred. Examples of carbon black include acetylene black, ketjen black, and furnace black.
　結着剤としては、例えばポリテトラフルオロエチレン(ＰＴＦＥ)、ポリフッ化ビニリデン(ＰＶｄＦ)、ポリアクリル酸、フッ素系ゴムなどが挙げられる。 Examples of the binder include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), polyacrylic acid, and fluorine rubber.
　正極材料層の目付量は、１０ｇ／ｍ2以上３００ｇ／ｍ2以下の範囲にすることが望ましい。さらに好ましい範囲は、２０ｇ／ｍ2以上２２０ｇ／ｍ2以下である。 The basis weight of the positive electrode material layer is desirably in the range of 10 g / m 2 to 300 g / m 2 . A more preferable range is 20 g / m 2 or more and 220 g / m 2 or less.
　正極材料層の密度は、２ｇ／ｍ3以上４．５ｇ／ｍ3以下の範囲にすることが望ましい。さらに好ましい範囲は、２．８ｇ／ｃｍ3以上４ｇ／ｃｍ3以下である。 The density of the positive electrode material layer is desirably in the range of 2 g / m 3 or more and 4.5 g / m 3 or less. A more preferable range is 2.8 g / cm 3 or more and 4 g / cm 3 or less.
　正極は、例えば、以下の手順で作製することができる。まず、正極活物質に導電剤及び結着剤を添加し、これらを適当な溶媒に懸濁させ、懸濁物（スラリー）を得る。次いで、この懸濁物をアルミニウム箔などの帯状の集電体の両面又は片面に塗布し、塗膜を乾燥させる。この際、集電体の一部に、懸濁物未塗布部を残してもよい。次いで、塗膜をプレスして、帯状電極にすることにより、正極を得ることができる。 The positive electrode can be produced, for example, by the following procedure. First, a conductive agent and a binder are added to the positive electrode active material, and these are suspended in an appropriate solvent to obtain a suspension (slurry). Next, this suspension is applied to both sides or one side of a belt-like current collector such as an aluminum foil, and the coating film is dried. At this time, the suspension uncoated portion may be left in a part of the current collector. Subsequently, a positive electrode can be obtained by pressing a coating film into a strip electrode.
　正極活物質、導電剤及び結着剤の配合比は、正極活物質８０～９５重量％、導電剤３～２０重量％、結着剤２～７重量％の範囲にすることが好ましい。 The compounding ratio of the positive electrode active material, the conductive agent and the binder is preferably in the range of 80 to 95% by weight of the positive electrode active material, 3 to 20% by weight of the conductive agent, and 2 to 7% by weight of the binder.
　３）セパレータ
　セパレータは、細孔と繊維とを含む多孔質繊維シートを含む。 3) Separator The separator includes a porous fiber sheet including pores and fibers.
　繊維の材料としては、特に限定されないが、例えば、ポリオレフィン、セルロース、ポリエステル、ポリビニルアルコール、ポリアミド、ポリイミド、ポリテトラフルオロエチレン及びビニロンよりなる群から選ばれる少なくとも１種類のポリマーを挙げることができる。繊維は、上記材料のうちの１種類からなっていてもよいし、又は上記材料のうちの２種類以上を含んでいてもよい。 The material of the fiber is not particularly limited, and examples thereof include at least one polymer selected from the group consisting of polyolefin, cellulose, polyester, polyvinyl alcohol, polyamide, polyimide, polytetrafluoroethylene, and vinylon. The fiber may consist of one of the above materials or may contain two or more of the above materials.
　多孔質繊維シートは、このような繊維を含む不織布であってもよいし、又は多孔質フィルムであってもよい。 The porous fiber sheet may be a non-woven fabric containing such fibers, or may be a porous film.
　セパレータは、多孔質繊維シート以外の材料を含んでいてもよい。セパレータは、例えば無機粒子を含んでいてもよい。或いは、セパレータは、多孔質繊維シートからなっていてもよい。言い換えると、セパレータは、多孔質繊維シートであってもよい。 The separator may contain a material other than the porous fiber sheet. The separator may contain inorganic particles, for example. Alternatively, the separator may be made of a porous fiber sheet. In other words, the separator may be a porous fiber sheet.
　多孔質繊維シートの厚さは、４μｍ以上３０μｍ以下であることが望ましく、８μｍ以上２５μｍ以下であることがより好ましい。セパレータの厚さも、４μｍ以上３０μｍ以下であることが望ましく、８μｍ以上２５μｍ以下であることがより好ましい。 The thickness of the porous fiber sheet is preferably 4 μm or more and 30 μm or less, and more preferably 8 μm or more and 25 μm or less. The thickness of the separator is also preferably 4 μm or more and 30 μm or less, and more preferably 8 μm or more and 25 μm or less.
　透地率が１０％以上２０％以下であり且つ８×１０-9ｍ2以上である細孔面積を有する細孔と繊維とを含む多孔質繊維シートを含むセパレータは、例えば、坪量が５ｇ／ｍ2以上２０ｇ／ｍ2以下となり且つ繊維の平均幅が１０μｍ以上４０μｍ以下となるように繊維の量及びプレス条件などを複合的に選択して抄紙することにより、製造することができる。或いは、多孔質繊維シートは、例えば正極及び／又は負極表面上に原材料の溶液を供給して直接形成してもよい。このようにして形成した多孔質繊維シートは、プレスに供してもよい。 The separator including a porous fiber sheet including pores and fibers having a porosity of 10% or more and 20% or less and a pore area of 8 × 10 −9 m 2 or more has a basis weight of, for example, 5 g. / M 2 or more and 20 g / m 2 or less, and the paper can be produced by making papers by selecting the amount of fibers and press conditions so that the average width of the fibers is 10 μm or more and 40 μm or less. Alternatively, the porous fiber sheet may be directly formed by supplying a raw material solution on the positive electrode and / or negative electrode surface, for example. The porous fiber sheet thus formed may be subjected to pressing.
　次に、図面を参照しながら、第１の実施形態に係る電極群の幾つかの例を説明する。 Next, some examples of the electrode group according to the first embodiment will be described with reference to the drawings.
　まず、第１の例の電極群を、図１及び図２を参照しながら説明する。 First, the electrode group of the first example will be described with reference to FIG. 1 and FIG.
　図１は、第１の実施形態に係る一例の電極群の一部展開概略斜視図である。図２は、図１に示す電極群のＡ部の拡大断面図である。 FIG. 1 is a partially developed schematic perspective view of an example electrode group according to the first embodiment. FIG. 2 is an enlarged cross-sectional view of part A of the electrode group shown in FIG.
　図１及び図２に示す第１の例の電極群１は、偏平形状の巻回型の電極群である。この電極群１は、図１及び図２に示す負極２と、図１及び図２に示す正極３と、図１及び図２に示す２枚のセパレータ４とを具備する。 The electrode group 1 of the first example shown in FIGS. 1 and 2 is a flat wound electrode group. The electrode group 1 includes a negative electrode 2 shown in FIGS. 1 and 2, a positive electrode 3 shown in FIGS. 1 and 2, and two separators 4 shown in FIGS.
　負極２は、図１及び図２に示すように、例えば金属箔からなる帯状の負極集電体２ａと、負極集電体２ａの長辺に平行な一端部からなる負極集電タブ２ｃと、負極集電体２ａのうち負極集電タブ２ｃを除いた部分の両面上に形成された負極材料層（負極活物質含有層）２ｂとを含む。負極材料層２ｂは、リチウムチタン複合酸化物を含む。 As shown in FIGS. 1 and 2, the negative electrode 2 includes a strip-shaped negative electrode current collector 2a made of, for example, a metal foil, and a negative electrode current collector tab 2c made of one end parallel to the long side of the negative electrode current collector 2a. A negative electrode material layer (negative electrode active material-containing layer) 2b formed on both surfaces of the negative electrode current collector 2a excluding the negative electrode current collector tab 2c. The negative electrode material layer 2b contains a lithium titanium composite oxide.
　正極３は、図１及び図２に示すように、例えば金属箔からなる帯状の正極集電体３ａと、正極集電体３ａの長辺に平行な一端部からなる正極集電タブ３ｃと、正極集電体３ａのうち正極集電タブ３ｃを除いた部分の両面上に形成された正極材料層（正極活物質含有層）３ｂとを含む。 As shown in FIGS. 1 and 2, the positive electrode 3 includes, for example, a strip-like positive electrode current collector 3a made of a metal foil, and a positive electrode current collector tab 3c made of one end parallel to the long side of the positive electrode current collector 3a. A positive electrode material layer (positive electrode active material-containing layer) 3b formed on both surfaces of the positive electrode current collector 3a excluding the positive electrode current collector tab 3c.
　セパレータ４は、負極材料層２ｂと正極材料層３ｂとの間に挟まれた部分を含む。各セパレータ４は、図１に示すように、ＭＤ方向（machine direction）に延びた帯状の平面形状を有している。図１では、セパレータ４のＭＤ方向と垂直な方向を、ＴＤ(transverse direction)と表示している。 The separator 4 includes a portion sandwiched between the negative electrode material layer 2b and the positive electrode material layer 3b. As shown in FIG. 1, each separator 4 has a belt-like planar shape extending in the MD direction (machine direction). In FIG. 1, the direction perpendicular to the MD direction of the separator 4 is indicated as TD (transverse direction).
　セパレータ４は、１０％以上２０％以下である透地率を示し、細孔面積が８×１０-9ｍ2以上である細孔と繊維とを含む多孔質繊維シートを含む。そのため、第１の例の電極群１では、正極３と負極２とが向き合った方向（例えば図２における線分Ｉ－Ｉ’で示す方向）における流体の移動を促進することができる。そして、負極材料層２ｂは、リチウムチタン複合酸化物を含む。これらの結果、第１の例の電極群１は、先に説明した理由により、ガス発生を十分に抑えることができる非水電解質電池を実現することができる。 The separator 4 includes a porous fiber sheet that has a permeability of 10% or more and 20% or less and includes pores and fibers having a pore area of 8 × 10 −9 m 2 or more. Therefore, in the electrode group 1 of the first example, it is possible to promote fluid movement in the direction in which the positive electrode 3 and the negative electrode 2 face each other (for example, the direction indicated by the line segment II ′ in FIG. 2). The negative electrode material layer 2b includes a lithium titanium composite oxide. As a result, the electrode group 1 of the first example can realize a non-aqueous electrolyte battery that can sufficiently suppress gas generation for the reason described above.
　図１及び図２に示す電極群１は、以下の手順で作製することができる。まず、１枚のセパレータ４と、正極３と、もう１枚のセパレータ４と、負極２とをこの順で積層して積層体を得る。積層の際、２枚のセパレータ４のＭＤ方向を揃える。また、負極集電体２ａ及び正極集電体３ａが延びている方向も、セパレータ４のＭＤ方向と平行になるようにする。また、図１に示すように、負極集電タブ２ｃがセパレータ４及び正極３に重ならないように、且つ正極集電タブ３ｃがセパレータ４及び負極２に重ならないように、各部材をＴＤ方向にずらして積層する。 The electrode group 1 shown in FIGS. 1 and 2 can be manufactured by the following procedure. First, one separator 4, the positive electrode 3, another separator 4, and the negative electrode 2 are laminated in this order to obtain a laminate. When laminating, the MD directions of the two separators 4 are aligned. The direction in which the negative electrode current collector 2 a and the positive electrode current collector 3 a extend is also made parallel to the MD direction of the separator 4. Further, as shown in FIG. 1, each member is placed in the TD direction so that the negative electrode current collecting tab 2 c does not overlap the separator 4 and the positive electrode 3 and so that the positive electrode current collecting tab 3 c does not overlap the separator 4 and the negative electrode 2. Lay and stack.
　次いで、得られた積層体を、正極３が負極２よりも外側にくるように、捲回軸ｗを軸として巻回し、巻回体を得る。先に説明したようにずらして積層することにより、図１に示したように、この巻回体において、正極集電タブ３ｃが、捲回軸ｗと平行な方向に負極２から突出する。また、同じく図１に示したように、負極集電タブ２ｃが、捲回軸ｗと平行な方向であって、正極集電タブ３ｃが突出した向きとは逆向きに、正極３から突出する。 Next, the obtained laminate is wound around the winding axis w so that the positive electrode 3 comes outside the negative electrode 2 to obtain a wound body. By laminating the layers as described above, as shown in FIG. 1, in this wound body, the positive electrode current collecting tab 3c protrudes from the negative electrode 2 in a direction parallel to the winding axis w. Similarly, as shown in FIG. 1, the negative electrode current collecting tab 2c protrudes from the positive electrode 3 in a direction parallel to the winding axis w and opposite to the direction in which the positive electrode current collecting tab 3c protrudes. .
　巻芯を抜いた後、かくして得られた巻回体をプレスに供することにより、図１に示す扁平形状を有する巻回型電極群１を得ることができる。 After removing the winding core, the wound electrode group 1 having a flat shape shown in FIG. 1 can be obtained by subjecting the wound body thus obtained to a press.
　次に、第２の例の電極群を、図３及び図４を参照しながら説明する。 Next, the electrode group of the second example will be described with reference to FIGS.
　図３は、第１の実施形態に係る他の例の電極群の概略斜視図である。図４は、図３に示す電極群の線分Ｘ－Ｘに沿った断面図である。 FIG. 3 is a schematic perspective view of another example electrode group according to the first embodiment. 4 is a cross-sectional view taken along line XX of the electrode group shown in FIG.
　図３及び図４に示す電極群１は、積層型の構造を有する電極群である。電極群１は、図４に示すように、複数（例えば２枚）の負極２1及び２2と、複数（例えば２枚）の正極３1及び３2と、複数（例えば５枚）のセパレータ４とを含む。 The electrode group 1 shown in FIGS. 3 and 4 is an electrode group having a laminated structure. As shown in FIG. 4, the electrode group 1 includes a plurality (for example, two sheets) of negative electrodes 2 1 and 2 2 , a plurality (for example, two sheets) of positive electrodes 3 1 and 3 2, and a plurality (for example, five sheets) of separators. 4 is included.
　一方の負極２1は、図４に示すように、帯状の負極集電体２ａと、負極集電体２ａの両方の表面上に形成された負極材料層（負極活物質含有層）２ｂとを含む。他方の負極２2は、図４に示すように、帯状の負極集電体２ａと、負極集電体２ａの片方の表面上に形成された負極材料層２ｂとを含む。図示はしていないが、負極２1及び２2のそれぞれの負極集電体２ａは、何れの表面にも負極材料層２ｂを担持していない部分（負極集電タブ）を含む。また、負極２1及び２2のそれぞれの負極材料層２ｂは、リチウムチタン複合酸化物を含んでいる。 One of the negative electrode 2 1, as shown in FIG. 4, a negative electrode current collector 2a of the strip, the anode material layer formed on both surfaces of the negative electrode current collector 2a and a (negative electrode active material-containing layer) 2b Including. Anode 2 2 other, as shown in FIG. 4, includes a negative electrode current collector 2a of the strip, and a negative electrode material layer 2b formed on one surface of the negative electrode current collector 2a. Although not shown, each of the negative electrode current collectors 2a of the negative electrodes 2 1 and 2 2 includes a portion (negative electrode current collection tab) that does not carry the negative electrode material layer 2b on any surface. Moreover, each negative electrode material layer 2b of the negative electrodes 2 1 and 2 2 contains a lithium titanium composite oxide.
　同様に、一方の正極３1は、図４に示すように、帯状の正極集電体３ａと、正極集電体３ａの両方の表面上に形成された正極材料層（正極活物質含有層）３ｂとを含む。他方の正極３2は、図４に示すように、帯状の正極集電体３ａと、正極集電体３ａの片方の表面上に形成された正極材料層３ｂとを含む。図示はしていないが、正極３1及び３2のそれぞれの正極集電体３ａは、何れの表面にも正極材料層３ｂを担持していない部分（正極集電タブ）を含む。 Similarly, as shown in FIG. 4, one positive electrode 31 has a positive electrode material layer (positive electrode active material-containing layer) formed on the surfaces of both the strip-shaped positive electrode current collector 3a and the positive electrode current collector 3a. 3b. The other of the positive electrode 3 2, as shown in FIG. 4, includes a band-like positive electrode current collector 3a, and a positive electrode layer 3b formed on one surface of the positive electrode current collector 3a. Although not shown, each of the positive electrode current collectors 3a of the positive electrodes 3 1 and 3 2 includes a portion (positive electrode current collecting tab) that does not carry the positive electrode material layer 3b on any surface.
　図４に示すように、１枚のセパレータ４の上に、このセパレータ４に負極集電体２ａのうち負極材料層２ｂを担持していない方の表面に接するように、負極２2が重ねられている。この負極２2の負極材料層２ｂ上に１枚のセパレータ４が重ねられ、その上に正極３1が重ねられている。それにより、負極２2の負極材料層２ｂが、セパレータ４を間に挟んで、正極３1の一方の正極材料層３ｂに対向している。また、正極３1の他方の正極材料層３ｂ上に１枚のセパレータ４が重ねられ、その上に負極２1が重ねられている。それにより、正極３1の正極材料層３ｂが、セパレータ４を間に挟んで、負極２1の一方の負極材料層２ｂに対向している。負極２1の他方の負極材料層２ｂ上に１枚のセパレータ４が重ねられ、その上に正極３2が重ねられている。それにより、正極３2の正極材料層３ｂが、セパレータ４を間に挟んで、負極２1の他方の負極材料層２ｂに対向している。そして、正極３2の正極集電体３ａ上に残りのセパレータ４が重ねられている。複数の負極２1及び２2と、複数の正極３1及び３2と、複数のセパレータ４とは、以上のように積層されて、電極群１を形成している。なお、図４に示すように、多孔質繊維シート４のうち、電極群１の最上層及び最下層の多孔質繊維シート４は、正極と負極との間に挟まれていない。 As shown in FIG. 4, on a piece of separator 4, to be in contact with the surface of which is not carrying the negative electrode layer 2b of the negative electrode current collector 2a in the separator 4, the negative electrode 2 2 is superimposed ing. The negative electrode 2 of one on 2 of the negative electrode material layer 2b separator 4 are superposed, the positive electrode 3 1 are stacked thereon. Thereby, the negative electrode material layer 2b of the negative electrode 2 2, sandwiched between the separator 4, and faces the one of the positive electrode material layer 3b of the cathode 3 1. Further, one separator 4 is superimposed on the other of the positive electrode material layer 3b of the cathode 3 1, negative electrode 2 1 are stacked thereon. Thereby, the positive electrode material layer 3b of the cathode 3 1, sandwiched between the separator 4, and face one of the negative electrode material layer 2b of the negative electrode 2 1. One separator 4 is stacked on the other negative electrode material layer 2 b of the negative electrode 21, and the positive electrode 3 2 is stacked thereon. Thereby, the positive electrode material layer 3b of the cathode 3 2, sandwiched between the separator 4, and faces the other of the negative electrode material layer 2b of the negative electrode 2 1. The remaining separator 4 are stacked on the cathode 3 2 positive electrode current collector 3a. The plurality of negative electrodes 2 1 and 2 2 , the plurality of positive electrodes 3 1 and 3 2, and the plurality of separators 4 are stacked as described above to form the electrode group 1. As shown in FIG. 4, among the porous fiber sheets 4, the uppermost layer and the lowermost porous fiber sheet 4 of the electrode group 1 are not sandwiched between the positive electrode and the negative electrode.
　先に説明した負極集電タブのそれぞれは、図３に示す負極リード７に電気的に接続されている。同様に、先に説明した正極集電タブのそれぞれは、図３に示す正極リード６に電気的に接続されている。正極リード６の先端及び負極リード７の先端は、図３に示すように、それぞれ反対の向きに電極群１から延出している。 Each of the negative electrode current collecting tabs described above is electrically connected to the negative electrode lead 7 shown in FIG. Similarly, each of the positive electrode current collecting tabs described above is electrically connected to the positive electrode lead 6 shown in FIG. As shown in FIG. 3, the tip of the positive electrode lead 6 and the tip of the negative electrode lead 7 extend from the electrode group 1 in opposite directions.
　各セパレータ４は、１０％以上２０％以下である透地率を示し、細孔面積が８×１０-9ｍ2以上である細孔と繊維とを含む多孔質繊維シートを含む。そのため、第２の例の電極群１では、正極３1と負極２2とが向き合った方向、正極３1と負極２1とが向き合った方向、及び負極２1と正極３2とが向き合った方向、すなわち図４における線分ＩＩ－ＩＩ’で示す方向における流体の移動を促進することができる。そして、負極材料層２ｂは、リチウムチタン複合酸化物を含む。これらの結果、第２の例の電極群１は、先に説明した理由により、ガス発生を十分に抑えることができる非水電解質電池を実現することができる。 Each separator 4 shows a Toruchi rate is 20% or less than 10%, pore area comprises a porous fibrous sheet containing pores and the fibers is 8 × 10 -9 m 2 or more. Therefore, the electrode group 1 in the second example, the positive electrode 3 1 and the negative electrode 2 2 and the direction of opposing the positive electrode 3 1 and the negative electrode 2 1 a is a direction opposed, and the negative electrode 2 1 and the positive electrode 3 2 facing The movement of the fluid in the direction, that is, the direction indicated by the line segment II-II ′ in FIG. 4 can be promoted. The negative electrode material layer 2b includes a lithium titanium composite oxide. As a result, the electrode group 1 of the second example can realize a non-aqueous electrolyte battery that can sufficiently suppress gas generation for the reason described above.
　＜各種測定方法＞
　次に、電極群に対して行う各種測定の手順を説明する。　
　［前処理］
　測定対象の電極群が非水電解質電池に組み込まれている場合は、以下の手順で前処理を行う。 <Various measurement methods>
Next, various measurement procedures performed on the electrode group will be described.
[Preprocessing]
When the electrode group to be measured is incorporated in the nonaqueous electrolyte battery, pretreatment is performed according to the following procedure.
　まず、非水電解質電池を、ＳＯＣ０％の状態まで放電する。続いて、電池充電深度がＳＯＣ０％となった非水電解質電池を、グローブボックス内、アルゴン雰囲気下で解体する。解体した非水電解質電池から、電極群を取り出す。 First, the nonaqueous electrolyte battery is discharged to a state of SOC 0%. Subsequently, the non-aqueous electrolyte battery having a battery charge depth of SOC 0% is disassembled in a glove box under an argon atmosphere. An electrode group is taken out from the disassembled nonaqueous electrolyte battery.
　取り出した電極群を、適切な溶媒、例えばメチルエチルカーボネートによって洗浄する。洗浄後、電極群を乾燥させる。 The electrode group taken out is washed with an appropriate solvent such as methyl ethyl carbonate. After washing, the electrode group is dried.
　かくして、電極群を得る。なお、非水電解質電池に組み込まれていない電極群について測定を行う場合は、以上の工程を省くことができる。 Thus, an electrode group is obtained. In addition, when measuring about the electrode group which is not integrated in the nonaqueous electrolyte battery, the above process can be omitted.
　［セパレータの取出し］
　以上のようにして得られた電極群から、セパレータを取り出す。この際、セパレータは、正極又は負極の何れかに担持された状態で取り出す。 [Removal of separator]
The separator is taken out from the electrode group obtained as described above. At this time, the separator is taken out while being supported on either the positive electrode or the negative electrode.
　＜電極群に含まれているセパレータの透地率の測定方法、多孔質繊維シートに含まれている細孔の細孔面積の測定方法＞
　［走査型電子顕微鏡観察］
　取り出したセパレータの任意の５箇所を、走査型電子顕微鏡（ＳＥＭ）で観察する。観察倍率は５００倍とする。測定方向は、測定対象のセパレータを含んでいた電極群において、セパレータの主面と正極又は負極が向き合っていた方向、すなわち正極と負極とが向き合っていた方向とする。 <Measurement method of permeability of separator contained in electrode group, measurement method of pore area of pores contained in porous fiber sheet>
[Scanning electron microscope observation]
The arbitrary five places of the taken-out separator are observed with a scanning electron microscope (SEM). The observation magnification is 500 times. The measurement direction is the direction in which the main surface of the separator and the positive electrode or the negative electrode face each other, that is, the direction in which the positive electrode and the negative electrode face each other in the electrode group including the separator to be measured.
　得られた５箇所のＳＥＭ像をコンピュータ分析に供することにより、最大の貫通孔面積を得ることができる。この面積を、セパレータに含まれる多孔質繊維シートが含む細孔の最大面積［ｍ2］とする。この分析により、セパレータに含まれる多孔質繊維シートが含む細孔の最大の直径［μｍ］も求めることができる。 By using the obtained five SEM images for computer analysis, the maximum through-hole area can be obtained. This area is defined as the maximum area [m 2 ] of pores included in the porous fiber sheet included in the separator. By this analysis, the maximum diameter [μm] of the pores included in the porous fiber sheet included in the separator can also be obtained.
　［二値化処理］
　先に得られた５箇所のＳＥＭ像を、以下の手順で画像処理に供する。なお、以下の画像処理は、画像から繊維の縁及び活物質の縁を検出する処理、並びに画像を二値化することができる処理を行うことができるアプリケーションを備えたソフトウェアにより行うことができる。例えば、画像処理には、画像処理プログラム「Ｉｍａｇｅ Ｊ」（フリーソフト（開発：アメリカ国立衛生研究所）、英語版ver. 1.48）を用いることができる。 [Binarization processing]
The five SEM images obtained previously are subjected to image processing according to the following procedure. The following image processing can be performed by software including an application capable of performing processing for detecting the edge of the fiber and the edge of the active material from the image and processing for binarizing the image. For example, an image processing program “Image J” (free software (development: National Institutes of Health), English version ver. 1.48) can be used for image processing.
　（１）得られたＳＥＭ像を、コンピュータ上で開く。開いた画像において、多孔質繊維シートの繊維の縁、及びセパレータを担持している電極材料層に含まれる活物質の縁を検出する。 (1) Open the obtained SEM image on the computer. In the opened image, the edge of the fiber of the porous fiber sheet and the edge of the active material contained in the electrode material layer supporting the separator are detected.
　（２）次いで、上記ソフトウェアを用いて、画像を二値化処理する。この処理は、繊維の存在している箇所が明部となるように行う。 (2) Next, the image is binarized using the above software. This treatment is performed so that the portion where the fiber is present becomes a bright portion.
　（３）二値化処理した画像において、活物質の縁に囲まれた部分が明部となるように処理を行う。活物質が写っているということは、その箇所には多孔質繊維シートの繊維が存在していないことを意味する。 (3) In the binarized image, processing is performed so that a portion surrounded by the edge of the active material becomes a bright portion. The fact that the active material is reflected means that the fiber of the porous fiber sheet does not exist in that portion.
　（４）以上の処理を行った画像において、暗部の面積割合を分析する。 (4) Analyze the area ratio of the dark part in the image subjected to the above processing.
　（５）同様の手順を繰り返し、５つの画像についての暗部の面積割合の平均値を算出する。かくして、多孔質繊維シートのＳＥＭ像を二値化処理によって得られた画像において、セパレータの材料である繊維が存在していない部分の割合、すなわちセパレータの透地率［％］を求めることができる。 (5) The same procedure is repeated, and the average value of the dark area ratio for the five images is calculated. Thus, in the image obtained by binarizing the SEM image of the porous fiber sheet, it is possible to obtain the ratio of the portion where the fiber as the separator material is not present, that is, the separator permeability [%]. .
　なお、セパレータが多孔質繊維シート以外の材料を含んでいる場合には、先に説明した二値化処理の処理（１）において、得られたＳＥＭ像から、多孔質繊維シート以外の材料の縁を検出する。次いで、処理（２）において、繊維が存在している箇所に加え、繊維以外の材料が存在している箇所も明部となるように、画像を二値化処理する。 When the separator includes a material other than the porous fiber sheet, the edge of the material other than the porous fiber sheet is obtained from the obtained SEM image in the binarization process (1) described above. Is detected. Next, in the processing (2), the image is binarized so that a portion where a material other than the fiber is present becomes a bright portion in addition to a portion where the fiber is present.
　図５に、第１の実施形態に係る一例の電極群が具備するセパレータのＳＥＭ画像を二値化処理に供して得られた像を示す。 FIG. 5 shows an image obtained by subjecting the SEM image of the separator included in the example electrode group according to the first embodiment to a binarization process.
　図５において、暗部（黒色部）が、セパレータの材料が存在していない部分である。この部分は、測定対象のセパレータを具備していた電極群において正極と負極とが向き合っていた方向において、多孔質繊維シートの貫通孔を通して負極（負極材料層）が観察された部分である。図５に示したセパレータの透地率は、１８％であった。また、多孔質繊維シートが含む細孔の最大細孔面積は２０×１０-9ｍ2であった。 In FIG. 5, the dark part (black part) is a part where the separator material does not exist. This portion is a portion where the negative electrode (negative electrode material layer) was observed through the through hole of the porous fiber sheet in the direction in which the positive electrode and the negative electrode faced each other in the electrode group having the separator to be measured. The permeability of the separator shown in FIG. 5 was 18%. The maximum pore area of the pores contained in the porous fiber sheet was 20 × 10 −9 m 2 .
　＜繊維の平均幅の測定方法＞
　［走査型電子顕微鏡観察］
　先に説明したように電極群から取り出したセパレータの任意の５箇所を、走査型電子顕微鏡で観察する。ここでは、観察倍率を１０００倍とする。測定方向は、測定対象の多孔質繊維シートを含んでいた電極群において正極と負極とが向き合っていた方向とする。 <Measuring method of average width of fiber>
[Scanning electron microscope observation]
As described above, arbitrary five portions of the separator taken out from the electrode group are observed with a scanning electron microscope. Here, the observation magnification is 1000 times. The measurement direction is a direction in which the positive electrode and the negative electrode face each other in the electrode group including the porous fiber sheet to be measured.
　かくして得られた画像（ＳＥＭ像）において、３０μｍ以上の長さにわたって延びている繊維を全て選択する。選択した全ての繊維について、３０μｍ以上延びている長さ方向に対して直交する方向における寸法を測定する。それぞれの繊維に対して任意の５点を測定する。測定結果の最大値及び最小値を除いた平均値を、その繊維の幅とする。全ての繊維の幅の平均値を算出する。全ての繊維の幅のうち、最大値、最小値及び最も平均値に近い値を抽出する。その３つの値の平均値を、その画像における繊維の平均幅［μｍ］とする。 In the image thus obtained (SEM image), all the fibers extending over a length of 30 μm or more are selected. For all the selected fibers, the dimensions in the direction perpendicular to the length direction extending 30 μm or more are measured. Measure any five points for each fiber. The average value excluding the maximum and minimum values of the measurement result is defined as the width of the fiber. The average value of all fiber widths is calculated. Of the widths of all the fibers, the maximum value, the minimum value, and the value closest to the average value are extracted. The average value of the three values is defined as the average fiber width [μm] in the image.
　同様の手順を他の４つの画像についても行う。かくして、５つの画像の各々における繊維の平均幅［μｍ］が得られる。これら平均幅の平均値を、多孔質繊維シートが含む繊維の平均幅［μｍ］とする。 同 様 Repeat the same procedure for the other four images. Thus, the average width [μm] of the fibers in each of the five images is obtained. The average value of these average widths is defined as the average width [μm] of the fibers contained in the porous fiber sheet.
　図６に、第１の実施形態に係る一例の電極群が具備する多孔質繊維シートの１つのＳＥＭ画像を示す。図６に示すＳＥＭ像に含まれる繊維の平均幅は、１９μｍである。 FIG. 6 shows one SEM image of the porous fiber sheet included in the example electrode group according to the first embodiment. The average width of the fibers included in the SEM image shown in FIG. 6 is 19 μm.
　＜多孔質繊維シートの坪量の測定方法＞
　多孔質繊維シートの坪量［ｇ／ｍ2］は、ＪＩＳ Ｐ８１２４に規定された方法で測定することができる。 <Measurement method of basis weight of porous fiber sheet>
The basis weight [g / m 2 ] of the porous fiber sheet can be measured by a method defined in JIS P8124.
　＜多孔質繊維シートの透気度の測定方法＞
　先に説明したように、ガーレー法に基づく多孔質繊維シートの透気度は、ＪＩＳ－Ｐ８１１７で規定された方法によって測定することができる。 <Measurement method of air permeability of porous fiber sheet>
As described above, the air permeability of the porous fiber sheet based on the Gurley method can be measured by the method defined in JIS-P8117.
　＜正極活物質及び負極活物質の組成の同定方法＞
　電極群に含まれている正極活物質及び負極活物質の組成及び結晶構造は、以下の手順で同定をすることができる。 <Method for identifying composition of positive electrode active material and negative electrode active material>
The composition and crystal structure of the positive electrode active material and the negative electrode active material contained in the electrode group can be identified by the following procedure.
　１．正極及び負極の取出し
　先に説明した手順で、電極群を得る。次いで、得られた電極群から、正極及び負極をそれぞれ取り出す。取り出した正極及び負極をそれぞれ洗浄及び乾燥に供する。 1. Removal of positive electrode and negative electrode An electrode group is obtained by the procedure described above. Next, the positive electrode and the negative electrode are respectively taken out from the obtained electrode group. The taken out positive electrode and negative electrode are subjected to washing and drying, respectively.
　２．誘導結合プラズマ（Inductively Coupled Plasma：ＩＣＰ）発光分光分析
　乾燥させた正極から、正極材料層を、例えばスパチュラを用いて剥がす。
　剥がした正極材料層を酸加熱処理し、結着剤及び導電剤を取り除く。かくして得られた試料に対し、ＩＣＰ測定を実施する。 2. Inductively Coupled Plasma (ICP) Emission Spectroscopic Analysis The positive electrode material layer is peeled off from the dried positive electrode using, for example, a spatula.
The peeled positive electrode material layer is subjected to an acid heat treatment to remove the binder and the conductive agent. ICP measurement is performed on the sample thus obtained.
　測定対象元素は、Ｌｉ、Ａｌ、Ｍｎ、Ｂａ、Ｃａ、Ｃｅ、Ｃｏ、Ｃｒ、Ｃｕ、Ｆｅ、Ｈｆ、Ｋ、Ｌａ、Ｍｇ、Ｎａ、Ｎｉ、Ｐｂ、Ｓｉ、Ｔｉ、Ｙ、Ｚｎ及びＺｒとする。測定結果から各元素のモル分率を算出することで、正極活物質の全体の組成を同定することができる。 The measurement target elements are Li, Al, Mn, Ba, Ca, Ce, Co, Cr, Cu, Fe, Hf, K, La, Mg, Na, Ni, Pb, Si, Ti, Y, Zn, and Zr. . By calculating the molar fraction of each element from the measurement result, the entire composition of the positive electrode active material can be identified.
　負極活物質についても、同様の測定を行うことで、組成を同定することができる。 The composition of the negative electrode active material can be identified by performing the same measurement.
　３．Ｘ線回折（X-ray Diffraction：ＸＲＤ）測定
　乾燥させた正極についてＸＲＤ測定を実施する。回折角（２θ）の範囲を１０°から９０°とし、０．０２°ずつＸ線回折強度を測定する。かくして、ＸＲＤ測定結果が得られる。 3. X-ray diffraction (XRD) measurement XRD measurement is performed on the dried positive electrode. The range of the diffraction angle (2θ) is 10 ° to 90 °, and the X-ray diffraction intensity is measured by 0.02 °. Thus, the XRD measurement result is obtained.
　一方、ＩＣＰ分析による組成の同定結果に基づき、データベースから、活物質組成から推定される活物質の固有ピークのパターンを推定する。 On the other hand, based on the identification result of the composition by ICP analysis, the pattern of the intrinsic peak of the active material estimated from the active material composition is estimated from the database.
　推定したＸ線パターンと、実測のＸ線パターンとを比較することにより、正極層に含まれている正極活物質の結晶構造を同定することができる。負極活物質についても、同様の測定を行うことで、組成を同定することができる。 The crystal structure of the positive electrode active material contained in the positive electrode layer can be identified by comparing the estimated X-ray pattern with the actually measured X-ray pattern. The composition of the negative electrode active material can be identified by performing the same measurement.
　４．走査型電子顕微鏡（Scanning Electron Microscope：SEM）観察、エネルギー分散型Ｘ線分光法（Energy Dispersive X-ray Spectroscopy: EDX）及び電子エネルギー損失分光法（Electron Energy－Loss Spectroscopy： EELS）による分析
　正極材料層が複数種類の正極活物質を含んでいる場合、上記ＸＲＤ測定によって得られる実測のＸ線パターンは、複数種類の正極活物質に由来するピークを含む。各活物質に由来するピークは、他の活物質に由来するピークと重なる場合もあれば、重ならない場合もある。ピークが重ならない場合は、上記ＸＲＤ測定及びＩＣＰ分析により、正極に含まれる各正極活物質の組成及び混合比を知ることができる。 4). Scanning Electron Microscope (SEM) observation, Energy Dispersive X-ray Spectroscopy (EDX) and Electron Energy-Loss Spectroscopy (EELS) analysis When a plurality of types of positive electrode active materials are included, the actual X-ray pattern obtained by the XRD measurement includes peaks derived from the plurality of types of positive electrode active materials. A peak derived from each active material may or may not overlap with a peak derived from another active material. When the peaks do not overlap, the composition and mixing ratio of each positive electrode active material contained in the positive electrode can be known by the XRD measurement and ICP analysis.
　一方、ピークが重なる場合は、ＳＥＭ観察、ＥＤＸ分析及びＥＥＬＳ分析により、正極材料層に含まれる各正極活物質の組成及び混合比を決定する。具体的には、以下のとおりである。 On the other hand, when the peaks overlap, the composition and mixing ratio of each positive electrode active material contained in the positive electrode material layer are determined by SEM observation, EDX analysis, and EELS analysis. Specifically, it is as follows.
　まず、乾燥させた正極から、カッターなどで約２ｃｍ×２ｃｍの断片を切り出す。切り出した断片の断面に、加速電圧２～６ｋＶで加速したアルゴンイオンを照射して、平坦な断面を得る。 First, a piece of about 2 cm × 2 cm is cut out from the dried positive electrode with a cutter or the like. The section of the cut piece is irradiated with argon ions accelerated at an acceleration voltage of 2 to 6 kV to obtain a flat section.
　次に、ＥＤＸ及びＥＥＬＳを付属したＳＥＭを用いて、正極断面に含まれる幾つかの活物質粒子の組成を分析する。ＥＤＸでは、Ｂ～Ｕまでの元素の定量分析をすることができる。Ｌｉについては、ＥＥＬＳによって定量分析することができる。かくして、正極材料層に含まれる各正極活物質の組成を知ることができる。 Next, the composition of some active material particles included in the cross section of the positive electrode is analyzed using an SEM with EDX and EELS. With EDX, the elements B to U can be quantitatively analyzed. Li can be quantitatively analyzed by EELS. Thus, the composition of each positive electrode active material contained in the positive electrode material layer can be known.
　次いで、正極活物質の全体の組成と各正極活物質の組成とから、正極における正極活物質の混合比を知ることができる。 Next, the mixing ratio of the positive electrode active material in the positive electrode can be known from the overall composition of the positive electrode active material and the composition of each positive electrode active material.
　負極材料層が複数種類の負極活物質を含んでいる場合も、正極活物質についての手順と同様の手順を踏むことにより、各負極活物質の組成及び混合比を知ることができる。 When the negative electrode material layer contains a plurality of types of negative electrode active materials, the composition and mixing ratio of each negative electrode active material can be known by following the same procedure as that for the positive electrode active material.
　以上に説明した第１の実施形態によると、電極群が提供される。この電極群は、正極と、負極と、少なくとも正極と負極との間に配置されたセパレータとを具備する。セパレータの透地率は、１０％以上２０％以下である。セパレータは、細孔面積が８×１０-9ｍ2以上である細孔と繊維とを含む多孔質繊維シートを含む。この電極群は、正極と負極とが向き合った方向における流体の移動を促進することができる。また、負極がリチウムチタン複合酸化物を含む。これらの結果、第１の実施形態に係る電極群は、ガス発生を十分に抑えることができる非水電解質電池を実現することができる。 According to the first embodiment described above, an electrode group is provided. The electrode group includes a positive electrode, a negative electrode, and a separator disposed at least between the positive electrode and the negative electrode. The permeability of the separator is 10% or more and 20% or less. The separator includes a porous fiber sheet including pores having a pore area of 8 × 10 −9 m 2 or more and fibers. This electrode group can promote the movement of fluid in the direction in which the positive electrode and the negative electrode face each other. The negative electrode includes a lithium titanium composite oxide. As a result, the electrode group according to the first embodiment can realize a non-aqueous electrolyte battery that can sufficiently suppress gas generation.
　（第２の実施形態）
　第２の実施形態によると、非水電解質電池が提供される。この非水電解質電池は、第１の実施形態に係る電極群と、非水電解質とを具備する。 (Second Embodiment)
According to the second embodiment, a nonaqueous electrolyte battery is provided. This nonaqueous electrolyte battery includes the electrode group according to the first embodiment and a nonaqueous electrolyte.
　第２の実施形態に係る非水電解質電池において、非水電解質は、例えば、電極群中に保持され得る。例えば、電極群は、非水電解質に含浸されていてもよい。 In the nonaqueous electrolyte battery according to the second embodiment, the nonaqueous electrolyte can be held, for example, in an electrode group. For example, the electrode group may be impregnated with a nonaqueous electrolyte.
　第２の実施形態に係る非水電解質電池は、正極端子及び負極端子を更に具備することができる。 The nonaqueous electrolyte battery according to the second embodiment can further include a positive electrode terminal and a negative electrode terminal.
　正極端子は、その一部が正極の一部に電気的に接続されることによって、正極と外部回路との間で電子が移動するための導体として働くことができる。正極端子は、例えば、正極集電体、特に正極集電タブに接続することができる。同様に、負極端子は、その一部が負極の一部に電気的に接続されることによって、負極と外部端子との間で電子が移動するための導体として働くことができる。負極端子は、例えば、負極集電体、特に負極集電タブに接続することができる。 The positive electrode terminal can function as a conductor for electrons to move between the positive electrode and an external circuit by being partially connected to a part of the positive electrode. The positive terminal can be connected to, for example, a positive current collector, particularly a positive current collector tab. Similarly, a part of the negative electrode terminal is electrically connected to a part of the negative electrode, whereby the negative electrode terminal can serve as a conductor for electrons to move between the negative electrode and the external terminal. The negative electrode terminal can be connected to, for example, a negative electrode current collector, particularly a negative electrode current collector tab.
　第２の実施形態に係る非水電解質電池は、外装部材を更に具備することができる。外装部材は、電極群及び非水電解質を収容することができる。正極端子及び負極端子のそれぞれの一部は、外装部材から延出させることができる。 The nonaqueous electrolyte battery according to the second embodiment can further include an exterior member. The exterior member can accommodate the electrode group and the nonaqueous electrolyte. A part of each of the positive electrode terminal and the negative electrode terminal can be extended from the exterior member.
　第１の実施形態に係る電極群は、先に説明したように、ガス発生の原因となり得るガスをより円滑に外部へ放出することができ、その結果、電極群におけるこれらのガスの滞留量を減らすことができる。そのおかげで、第２の実施形態に係る非水電解質電池は、ガス発生を十分に抑えることができる。また、例えば、第１の実施形態に係る電極群を用いて非水電解質電池を作製する一連の工程において、第１の実施形態に係る電極群は、乾燥に供されることにより、電極群が含むセパレータの透地率が１０％未満である電極群よりも容易に、水分を外部に放出することができる。それにより、水分量が少なく、ガス発生を十分に抑えることができる非水電解質電池を提供することができる。 As described above, the electrode group according to the first embodiment can smoothly discharge the gas that may cause gas generation to the outside, and as a result, the amount of retention of these gases in the electrode group can be reduced. Can be reduced. Thanks to that, the nonaqueous electrolyte battery according to the second embodiment can sufficiently suppress gas generation. Further, for example, in a series of steps for producing a non-aqueous electrolyte battery using the electrode group according to the first embodiment, the electrode group according to the first embodiment is subjected to drying, so that the electrode group is Moisture can be released to the outside more easily than the electrode group in which the permeability of the separator is less than 10%. Thereby, a non-aqueous electrolyte battery that has a small amount of water and can sufficiently suppress gas generation can be provided.
　以下、実施形態に係る非水電解質電池に含まれる各部材を説明する。 Hereinafter, each member included in the nonaqueous electrolyte battery according to the embodiment will be described.
　（Ａ）電極群
　電極群に関しては、第１の実施形態に係る電極群の説明を参照されたい。 (A) Electrode group Regarding the electrode group, refer to the description of the electrode group according to the first embodiment.
　（Ｂ）非水電解質
　この非水電解質は、非水溶媒と、この非水溶媒に溶解される電解質塩とを含むことができる。また、非水溶媒中にはポリマーを含んでもよい。 (B) Non-aqueous electrolyte This non-aqueous electrolyte can contain a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. Further, the non-aqueous solvent may contain a polymer.
　電解質塩の例としては、ＬｉＰＦ6、ＬｉＢＦ4、Ｌｉ（ＣＦ3ＳＯ2）2Ｎ（ビストリフルオロメタンスルホニルアミドリチウム；通称ＬｉＴＦＳＩ）、ＬｉＣＦ3ＳＯ3（通称ＬｉＴＦＳ）、Ｌｉ（Ｃ2Ｆ5ＳＯ2）2Ｎ（ビスペンタフルオロエタンスルホニルアミドリチウム；通称ＬｉＢＥＴＩ）、ＬｉＣｌＯ4、ＬｉＡｓＦ6、ＬｉＳｂＦ6、ビスオキサラトホウ酸リチウム（ＬｉＢ（Ｃ2Ｏ4）2（通称ＬｉＢＯＢ））、ジフルオロ（オキサラト）ホウ酸リチウム（ＬｉＦ2ＢＣ2Ｏ4）、ジフルオロ（トリフルオロ－２－オキシド－２－トリフルオロ－メチルプロピオナト（２－）－０，０）ホウ酸リチウム（ＬｉＢＦ2（ＯＣＯＯＣ（ＣＦ3）2）（通称ＬｉＢＦ2（ＨＨＩＢ）））、ジフルオロリン酸リチウム（ＬｉＰＯ2Ｆ2）等のリチウム塩が挙げられる。これらの電解質塩は、１種類で使用してもよいし又は２種類以上を混合して用いてもよい。特に、ＬｉＰＦ6、ＬｉＢＦ4、ビスオキサラトホウ酸リチウム（ＬｉＢ（Ｃ2Ｏ4）2（通称ＬｉＢＯＢ））、ジフルオロ（オキサラト）ホウ酸リチウム（ＬｉＦ2ＢＣ2Ｏ4）、ジフルオロ（トリフルオロ－２－オキシド－２－トリフルオロ－メチルプロピオナト（２－）－０，０）ホウ酸リチウム（ＬｉＢＦ2（ＯＣＯＯＣ（ＣＦ3）2）（通称ＬｉＢＦ2（ＨＨＩＢ）））、ジフルオロリン酸リチウム（ＬｉＰＯ2Ｆ2）が好ましい。 Examples of the electrolyte salt include LiPF 6 , LiBF 4 , Li (CF 3 SO 2 ) 2 N (bistrifluoromethanesulfonylamide lithium; commonly known as LiTFSI), LiCF 3 SO 3 (commonly known as LiTFS), and Li (C 2 F 5 SO 2) 2 N (bis pentafluoroethanesulfonyl amide lithium; called LiBETI), LiClO 4, LiAsF 6 , LiSbF 6, bisoxalato Lato lithium borate (LiB (C 2 O 4) 2 ( known as LiBOB)), difluoro (oxalato) Lithium borate (LiF 2 BC 2 O 4 ), difluoro (trifluoro-2-oxide-2-trifluoro-methylpropionate (2-)-0,0) lithium borate (LiBF 2 (OCOOC (CF 3 ) 2) (aka LiBF 2 (HHIB))), lithium difluorophosphate (LiPO 2 2) lithium salts, and the like. These electrolyte salts may be used alone or in combination of two or more. In particular, LiPF 6 , LiBF 4 , lithium bisoxalatoborate (LiB (C 2 O 4 ) 2 (commonly called LiBOB)), lithium difluoro (oxalato) borate (LiF 2 BC 2 O 4 ), difluoro (trifluoro-2 -Oxide-2-trifluoro-methylpropionate (2-)-0,0) lithium borate (LiBF 2 (OCOOC (CF 3 ) 2 ) (commonly known as LiBF 2 (HHIB))), lithium difluorophosphate (LiPO 2 F 2) is preferred.
　電解質塩濃度は、０．５Ｍ以上３Ｍ以下の範囲内とすることが好ましい。これにより、高負荷電流を流した場合の性能を向上することができる。 The electrolyte salt concentration is preferably in the range of 0.5M to 3M. Thereby, the performance when a high load current is passed can be improved.
　非水溶媒としては、特に限定されるものではないが、プロピレンカーボネート（ＰＣ）、エチレンカーボネート（ＥＣ）、１，２－ジメトキシエタン（ＤＭＥ）、γ－ブチロラクトン（ＧＢＬ）、テトラヒドロフラン（ＴＨＦ）、２－メチルテトラヒドロフラン（２－ＭｅＨＦ）、１，３－ジオキソラン、スルホラン、アセトニトリル（ＡＮ）、ジエチルカーボネート（ＤＥＣ）、ジメチルカーボネイト（ＤＭＣ）、メチルエチルカーボネート（ＭＥＣ）、ジプロピルカーボネート（ＤＰＣ）等が挙げられる。これらの溶媒は、１種類で使用してもよいし又は２種類以上を混合して用いてもよい。また、溶媒を二種類以上組み合わせる場合、全ての溶媒に誘電率が２０以上のものの中から選ぶことが好ましい。 The non-aqueous solvent is not particularly limited, but propylene carbonate (PC), ethylene carbonate (EC), 1,2-dimethoxyethane (DME), γ-butyrolactone (GBL), tetrahydrofuran (THF), 2 -Methyltetrahydrofuran (2-MeHF), 1,3-dioxolane, sulfolane, acetonitrile (AN), diethyl carbonate (DEC), dimethyl carbonate (DMC), methyl ethyl carbonate (MEC), dipropyl carbonate (DPC), etc. It is done. These solvents may be used alone or in combination of two or more. Further, when two or more kinds of solvents are combined, it is preferable to select from all solvents having a dielectric constant of 20 or more.
　この非水電解質に、添加剤を添加してもよい。添加剤としては、特に限定されるものではないが、ビニレンカーボネート（ＶＣ）、フルオロビニレンカーボネート、メチルビニレンカーボネート、フルオロメチルビニレンカーボネート、エチルビニレンカーボネート、プロピルビニレンカーボネート、ブチルビニレンカーボネート、ジメチルビニレンカーボネート、ジエチルビニレンカーボネート、ジプロピルビニレンカーボネート、ビニレンアセテート（ＶＡ）、ビニレンブチレート、ビニレンヘキサネート、ビニレンクロトネート、カテコールカーボネート、プロパンスルトン、及びブタンスルトン等が挙げられる。添加剤の種類は、１種類又は２種類以上にすることができる。 An additive may be added to this non-aqueous electrolyte. Although it does not specifically limit as an additive, Vinylene carbonate (VC), fluoro vinylene carbonate, methyl vinylene carbonate, fluoromethyl vinylene carbonate, ethyl vinylene carbonate, propyl vinylene carbonate, butyl vinylene carbonate, dimethyl vinylene carbonate, diethyl Examples include vinylene carbonate, dipropyl vinylene carbonate, vinylene acetate (VA), vinylene butyrate, vinylene hexanate, vinylene crotonate, catechol carbonate, propane sultone, and butane sultone. One kind or two or more kinds of additives can be used.
　（Ｃ）外装部材
　外装部材としては、例えば厚さが０．５ｍｍ以下であるラミネートフィルム又は厚さが３ｍｍ以下である金属製容器を用いることができる。金属製容器は、厚さが０．５ｍｍ以下であることがより好ましい。また、樹脂製容器を用いてもよい。樹脂製容器を形成する材料の例に、ポリオレフィン、ポリ塩化ビニル、ポリスチレン系樹脂、アクリル樹脂、フェノール樹脂、ポリフェニレン系樹脂、フッ素系樹脂等が含まれる。 (C) Exterior Member As the exterior member, for example, a laminate film having a thickness of 0.5 mm or less or a metal container having a thickness of 3 mm or less can be used. More preferably, the metal container has a thickness of 0.5 mm or less. A resin container may also be used. Examples of the material forming the resin container include polyolefin, polyvinyl chloride, polystyrene resin, acrylic resin, phenol resin, polyphenylene resin, fluorine resin, and the like.
　外装部材の形状、すなわち電池形状としては、扁平型（薄型）、角型、円筒型、コイン型、ボタン型等が挙げられる。また、電池は、例えば携帯用電子機器等に積載される小型用途、二輪乃至四輪の自動車等に積載される大型用途のいずれにも適用することができる。 Examples of the shape of the exterior member, that is, the battery shape, include a flat type (thin type), a square type, a cylindrical type, a coin type, and a button type. In addition, the battery can be applied to, for example, a small-sized application loaded on a portable electronic device or the like, and a large-sized application loaded on a two-wheel to four-wheeled vehicle.
　ラミネートフィルムは、金属層と、この金属層を間に挟みこむ樹脂層とを含む多層フィルムが用いられる。金属層は、軽量化のためにアルミニウム箔若しくはアルミニウム合金箔が好ましい。樹脂層としては、例えばポリプロピレン（ＰＰ）、ポリエチレン（ＰＥ）、ナイロン、ポリエチレンテレフタレート（ＰＥＴ）等の高分子材料を用いることができる。ラミネートフィルムは、熱融着によりシールを行って外装部材の形状に成形することができる。 As the laminate film, a multilayer film including a metal layer and a resin layer sandwiching the metal layer is used. The metal layer is preferably an aluminum foil or an aluminum alloy foil for weight reduction. As the resin layer, for example, a polymer material such as polypropylene (PP), polyethylene (PE), nylon, polyethylene terephthalate (PET) can be used. The laminate film can be formed into the shape of an exterior member by sealing by heat sealing.
　金属製容器は、アルミニウム又はアルミニウム合金等から作られる。アルミニウム合金は、マグネシウム、亜鉛及びケイ素よりなる群から選ばれる少なくとも１種類の元素等を含むことが好ましい。合金中に鉄、銅、ニッケル、クロム等の遷移金属が含まれる場合、その量は１００ｐｐｍ以下にすることが好ましい。 Metal containers are made of aluminum or aluminum alloy. The aluminum alloy preferably contains at least one element selected from the group consisting of magnesium, zinc and silicon. When transition metals, such as iron, copper, nickel, and chromium, are contained in an alloy, it is preferable that the quantity shall be 100 ppm or less.
　（Ｄ）負極端子
　負極端子は、アルミニウム、又は、Ｍｇ、Ｔｉ、Ｚｎ、Ｍｎ、Ｆｅ、Ｃｕ及びＳｉからなる群より選択される少なくとも１種類の元素を含有するアルミニウム合金から形成することができる。負極集電体との接触抵抗を低減するために、負極端子は負極集電体と同様の材料から形成されることが好ましい。 (D) Negative electrode terminal The negative electrode terminal can be formed from aluminum or an aluminum alloy containing at least one element selected from the group consisting of Mg, Ti, Zn, Mn, Fe, Cu, and Si. In order to reduce the contact resistance with the negative electrode current collector, the negative electrode terminal is preferably formed from the same material as the negative electrode current collector.
　（Ｅ）正極端子
　正極端子は、アルミニウム、又は、Ｍｇ、Ｔｉ、Ｚｎ、Ｎｉ、Ｃｒ、Ｍｎ、Ｆｅ、Ｃｕ及びＳｉよりなる群から選択される少なくとも１種類の元素を含有するアルミニウム合金から形成されることが好ましい。正極集電体との接触抵抗を低減するために、正極端子は正極集電体と同様の材料から形成されることが好ましい。 (E) Positive electrode terminal The positive electrode terminal is formed from aluminum or an aluminum alloy containing at least one element selected from the group consisting of Mg, Ti, Zn, Ni, Cr, Mn, Fe, Cu, and Si. It is preferable. In order to reduce the contact resistance with the positive electrode current collector, the positive electrode terminal is preferably formed of the same material as the positive electrode current collector.
　次に、第２の実施形態に係る一例の非水電解質電池を、図面を参照しながら具体的に説明する。 Next, an example of the nonaqueous electrolyte battery according to the second embodiment will be specifically described with reference to the drawings.
　図７は、第２の実施形態に係る一例の非水電解質電池の分解概略斜視図である。 FIG. 7 is an exploded schematic perspective view of an example nonaqueous electrolyte battery according to the second embodiment.
　図７に示す電池１０は、密閉型の角型非水電解質電池である。非水電解質電池１０は、外装缶１１と、封口板１２と、正極端子１３と、負極端子１４と、電極群１と、図示しない非水電解質とを備える。外装缶１１と封口板１２とから外装部材が構成されている。 The battery 10 shown in FIG. 7 is a sealed rectangular nonaqueous electrolyte battery. The nonaqueous electrolyte battery 10 includes an outer can 11, a sealing plate 12, a positive electrode terminal 13, a negative electrode terminal 14, an electrode group 1, and a nonaqueous electrolyte (not shown). An exterior member is composed of the exterior can 11 and the sealing plate 12.
　外装缶１１は、有底角筒形状をなし、例えば、アルミニウム、アルミニウム合金、鉄あるいはステンレス鋼などの金属から形成される。 The outer can 11 has a bottomed rectangular tube shape and is formed of a metal such as aluminum, an aluminum alloy, iron, or stainless steel.
　図７に示す電極群１は、以下の点以外は、図１及び図２を参照しながら説明した、扁平形状を有する巻回型電極群１と同様の構造を有している。 The electrode group 1 shown in FIG. 7 has the same structure as the wound electrode group 1 having a flat shape described with reference to FIGS. 1 and 2 except for the following points.
　まず、図７に示すように、正極集電タブ３ｃ及び負極集電タブ２ｃは、それぞれ、電極群１の捲回軸ｗ付近を境にして二つの束に分けられている。導電性の挟持部材５は、略Ｕの字状をした第１及び第２の挟持部５ａ及び５ｂと、第１の挟持部５ａと第２の挟持部５ｂとを電気的に接続する連結部５ｃとを有する。正極集電タブ３ｃ及び負極集電タブ２ｃは、それぞれ、一方の束が第１の挟持部５ａによって挟持され、かつ他方の束が第２の挟持部５ｂによって挟持されている。 First, as shown in FIG. 7, the positive electrode current collecting tab 3 c and the negative electrode current collecting tab 2 c are each divided into two bundles with the vicinity of the winding axis w of the electrode group 1 as a boundary. The conductive sandwiching member 5 includes first and second sandwiching portions 5a and 5b that are substantially U-shaped, and a connecting portion that electrically connects the first sandwiching portion 5a and the second sandwiching portion 5b. 5c. In each of the positive electrode current collecting tab 3c and the negative electrode current collecting tab 2c, one bundle is sandwiched by the first sandwiching portion 5a, and the other bundle is sandwiched by the second sandwiching portion 5b.
　また、電極群１のうち、正極集電タブ３ｃ及び負極集電タブ２ｃ以外の部分は、絶縁シール８によって被覆されている。　
　図示しない非水電解質は、電極群１に含浸された状態で、保持されている。 Further, portions of the electrode group 1 other than the positive electrode current collecting tab 3 c and the negative electrode current collecting tab 2 c are covered with an insulating seal 8.
A non-aqueous electrolyte (not shown) is held in a state where the electrode group 1 is impregnated.
　正極リード６は、矩形の支持板６ａと、支持板６ａに開口された貫通孔６ｂと、支持板６ａから二股に分岐し、下方に延出した短冊状の集電部６ｃ及び６ｄとを有する。一方、負極リード７は、矩形の支持板７ａと、支持板７ａに開口された貫通孔７ｂと、支持板７ａから二股に分岐し、下方に延出した短冊状の集電部７ｃ及び７ｄとを有する。 The positive electrode lead 6 includes a rectangular support plate 6a, a through-hole 6b opened in the support plate 6a, and strip-shaped current collectors 6c and 6d that are bifurcated from the support plate 6a and extend downward. . On the other hand, the negative electrode lead 7 includes a rectangular support plate 7a, a through hole 7b opened in the support plate 7a, a bifurcated bifurcated branch from the support plate 7a, and strip-shaped current collectors 7c and 7d extending downward. Have
　正極リード６の集電部６ｃ及び６ｄは、間に、正極集電タブ３ｃに取り付けられた挟持部材５を挟んでいる。集電部６ｃは、挟持部材５の第１の挟持部５ａに接している。一方、集電部６ｄは、第２の挟持部５ｂに接している。集電部６ｃ及び６ｄと、第１及び第２の挟持部５ａ及び５ｂと、正極集電タブ３ｃとは、例えば超音波溶接によって接合されている。これにより、電極群１の正極３と正極リード６とが正極集電タブ３ｃを介して電気的に接続されている。 The current collectors 6c and 6d of the positive electrode lead 6 sandwich the clamping member 5 attached to the positive electrode current collecting tab 3c therebetween. The current collector 6 c is in contact with the first clamping part 5 a of the clamping member 5. On the other hand, the current collector 6d is in contact with the second clamping unit 5b. The current collecting parts 6c and 6d, the first and second clamping parts 5a and 5b, and the positive electrode current collecting tab 3c are joined by, for example, ultrasonic welding. Thereby, the positive electrode 3 and the positive electrode lead 6 of the electrode group 1 are electrically connected via the positive electrode current collection tab 3c.
　負極リード７の集電部７ｃ及び７ｄは、間に、負極集電タブ２ｃに取り付けられた挟持部材５を挟んでいる。集電部７ｃは、挟持部材５の第１の挟持部５ａに接している。一方、集電部７ｄは、第２の挟持部５ｂに接している。集電部７ｃ及び７ｄと、第１及び第２の挟持部５ａ及び５ｂと、負極集電タブ２ｃとは、例えば超音波溶接によって接合されている。これにより、電極群１の負極２と負極リード７とが負極集電タブ２ｃを介して電気的に接続されている。 The current collecting portions 7c and 7d of the negative electrode lead 7 sandwich the holding member 5 attached to the negative electrode current collecting tab 2c therebetween. The current collector 7 c is in contact with the first clamping part 5 a of the clamping member 5. On the other hand, the current collector 7d is in contact with the second clamping unit 5b. The current collecting parts 7c and 7d, the first and second clamping parts 5a and 5b, and the negative electrode current collecting tab 2c are joined by, for example, ultrasonic welding. Thereby, the negative electrode 2 and the negative electrode lead 7 of the electrode group 1 are electrically connected via the negative electrode current collection tab 2c.
　正極リード６、及び正極集電タブ３ｃに取り付ける挟持部材５の材料は、特に限定されないが、正極端子１３の材料と同じであることが望ましい。正極端子１３には、例えば、アルミニウムあるいはアルミニウム合金が使用される。同様に、負極リード７、及び負極集電タブ２ｃに取り付ける挟持部材５の材料は、特に限定されないが、負極端子１４の材料と同じであることが望ましい。負極端子１４には、例えば、アルミニウム、アルミニウム合金、銅、ニッケル、ニッケルメッキされた鉄などが使用される。例えば、端子の材質がアルミニウム又はアルミニウム合金の場合は、それに接続するリードの材質をアルミニウム、アルミニウム合金にすることが好ましい。また、端子が銅の場合は、それに接続するリードの材質を銅などにすることが望ましい。 The material of the clamping member 5 attached to the positive electrode lead 6 and the positive electrode current collecting tab 3c is not particularly limited, but is preferably the same as the material of the positive electrode terminal 13. For the positive electrode terminal 13, for example, aluminum or an aluminum alloy is used. Similarly, the material of the holding member 5 attached to the negative electrode lead 7 and the negative electrode current collecting tab 2 c is not particularly limited, but is preferably the same as the material of the negative electrode terminal 14. For the negative electrode terminal 14, for example, aluminum, aluminum alloy, copper, nickel, nickel-plated iron, or the like is used. For example, when the material of the terminal is aluminum or aluminum alloy, the material of the lead connected to the terminal is preferably aluminum or aluminum alloy. Further, when the terminal is made of copper, it is desirable that the material of the lead connected to the terminal is made of copper or the like.
　矩形板状の封口板１２は、外装缶１１の開口部に、例えばレーザでシーム溶接されている。封口板１２は、例えば、アルミニウム、アルミニウム合金、鉄あるいはステンレス鋼などの金属から形成される。封口板１２と外装缶１１とは、同じ種類の金属から形成されることが望ましい。 The rectangular plate-shaped sealing plate 12 is seam welded to the opening of the outer can 11 by, for example, a laser. The sealing plate 12 is made of, for example, a metal such as aluminum, an aluminum alloy, iron, or stainless steel. It is desirable that the sealing plate 12 and the outer can 11 are formed of the same type of metal.
　正極端子１３は、正極リード６の支持板６ａと電気的に接続されている。同様に、負極端子１４は、負極リード７の支持板７ａと電気的に接続されている。正極端子１３と封口板１２との間、及び負極端子１４と封口板１２との間には、絶縁ガスケット１５がそれぞれ配置されている。かくして、正極端子１３及び負極端子１４が、封口板１２と電気的に絶縁されている。絶縁ガスケット１５は、樹脂成形品であることが望ましい。 The positive terminal 13 is electrically connected to the support plate 6 a of the positive lead 6. Similarly, the negative electrode terminal 14 is electrically connected to the support plate 7 a of the negative electrode lead 7. Insulating gaskets 15 are disposed between the positive terminal 13 and the sealing plate 12 and between the negative terminal 14 and the sealing plate 12, respectively. Thus, the positive terminal 13 and the negative terminal 14 are electrically insulated from the sealing plate 12. The insulating gasket 15 is preferably a resin molded product.
　第２の実施形態に係る非水電解質電池は、第１の実施形態に係る電極群を具備するので、ガス発生を十分に抑えることができる。 Since the nonaqueous electrolyte battery according to the second embodiment includes the electrode group according to the first embodiment, gas generation can be sufficiently suppressed.
　（第３の実施形態）
　第３の実施形態によると、電池パックが提供される。この電池パックは、第２の実施形態に係る非水電解質電池を具備する。 (Third embodiment)
According to the third embodiment, a battery pack is provided. This battery pack includes the nonaqueous electrolyte battery according to the second embodiment.
　第３の実施形態に係る電池パックは、１つの非水電解質電池（単電池）を含むこともできるし、又は複数の単電池を含むこともできる。複数の単電池を備える場合、各単電池は電気的に直列若しくは並列に接続されていてもよいし、又は直列及び並列の組み合わせで接続されていてもよい。 The battery pack according to the third embodiment can include one non-aqueous electrolyte battery (unit cell) or can include a plurality of unit cells. When a plurality of unit cells are provided, each unit cell may be electrically connected in series or in parallel, or may be connected in a combination of series and parallel.
　次に、第３の実施形態に係る電池パックの一例を、図８を参照しながら具体的に説明する。　
　図８は、第３の実施形態に係る一例の電池パックの電気回路を示すブロック図である。 Next, an example of the battery pack according to the third embodiment will be specifically described with reference to FIG.
FIG. 8 is a block diagram showing an electric circuit of an example battery pack according to the third embodiment.
　図８に示す電池パック２０は、複数の単電池２１を具備している。各単電池２１は、例えば、図７を参照しながら説明した非水電解質電池と同様の構造を有する。 The battery pack 20 shown in FIG. 8 includes a plurality of single cells 21. Each unit cell 21 has the same structure as the nonaqueous electrolyte battery described with reference to FIG.
　図８に示すように、複数の単電池２１は、互いに電気的に直列に接続され、組電池２２を構成している。正極側リード２３は、組電池２２の正極端子に接続され、その先端は正極側コネクタ２４に挿入されて電気的に接続されている。負極側リード２５は、組電池２２の負極端子に接続され、その先端は負極側コネクタ２６に挿入されて電気的に接続されている。これらのコネクタ２４及び２６は、配線２７及び２８をそれぞれ通して保護回路２９に接続されている。 As shown in FIG. 8, the plurality of single cells 21 are electrically connected to each other in series to form an assembled battery 22. The positive electrode side lead 23 is connected to the positive electrode terminal of the assembled battery 22, and the tip thereof is inserted into the positive electrode side connector 24 and electrically connected thereto. The negative electrode side lead 25 is connected to the negative electrode terminal of the assembled battery 22, and the tip thereof is inserted into the negative electrode side connector 26 and electrically connected thereto. These connectors 24 and 26 are connected to a protection circuit 29 through wires 27 and 28, respectively.
　サーミスタ３０は、単電池２１の温度を検出し、その検出信号は保護回路２９に送信される。保護回路２９は、所定の条件で保護回路２９と外部機器への通電用端子３１との間のプラス側配線３２ａ及びマイナス側配線３２ｂを遮断できる。所定の条件とは、例えばサーミスタ３０の検出温度が所定温度以上になったときである。また、所定の条件とは、単電池２１の過充電、過放電、過電流等を検出したときである。この過充電等の検出は、個々の単電池２１もしくは組電池２２全体について行われる。個々の単電池２１を検出する場合、電池電圧を検出してもよいし、又は正極電位若しくは負極電位を検出してもよい。後者の場合、個々の単電池２１中に参照極として用いるリチウム電極が挿入される。図８の場合、単電池２１それぞれに電圧検出のための配線３３を接続し、これら配線３３を通して検出信号が保護回路２９に送信される。 The thermistor 30 detects the temperature of the unit cell 21, and the detection signal is transmitted to the protection circuit 29. The protection circuit 29 can cut off the plus side wiring 32a and the minus side wiring 32b between the protection circuit 29 and the terminal 31 for energizing the external device under a predetermined condition. The predetermined condition is, for example, when the temperature detected by the thermistor 30 is equal to or higher than a predetermined temperature. The predetermined condition is when an overcharge, overdischarge, overcurrent, or the like of the unit cell 21 is detected. This detection of overcharge or the like is performed for each individual cell 21 or the entire assembled battery 22. When detecting each single cell 21, the battery voltage may be detected, or the positive electrode potential or the negative electrode potential may be detected. In the latter case, a lithium electrode used as a reference electrode is inserted into each unit cell 21. In the case of FIG. 8, the voltage detection wiring 33 is connected to each of the single cells 21, and the detection signal is transmitted to the protection circuit 29 through the wiring 33.
　図８では単電池２１を直列接続した形態を示したが、電池容量を増大させるためには並列に接続してもよい。組み上がった電池パックを直列及び／又は並列に接続することもできる。 Although FIG. 8 shows a mode in which the unit cells 21 are connected in series, they may be connected in parallel in order to increase the battery capacity. The assembled battery packs can be connected in series and / or in parallel.
　また、電池パックの態様は用途により適宜変更される。電池パックの用途としては、大電流特性でのサイクル特性が望まれるものが好ましい。具体的には、デジタルカメラの電源用や、二輪乃至四輪のハイブリッド電気自動車、二輪乃至四輪の電気自動車、アシスト自転車等の車載用が挙げられる。特に、車載用が好適である。 In addition, the mode of the battery pack is appropriately changed depending on the application. As the use of the battery pack, those in which cycle characteristics with large current characteristics are desired are preferable. Specific examples include a power source for a digital camera, a vehicle for a two- to four-wheel hybrid electric vehicle, a two- to four-wheel electric vehicle, an assist bicycle, and the like. In particular, the vehicle-mounted one is suitable.
　以上に説明した第３の実施形態に係る電池パックは、第２の実施形態に係る非水電解質電池を具備するので、ガス発生を十分に抑えることができる。 Since the battery pack according to the third embodiment described above includes the nonaqueous electrolyte battery according to the second embodiment, gas generation can be sufficiently suppressed.
　［実施例］
　以下に実施例を説明するが、本発明の主旨を超えない限り、本発明は以下に記載される実施例に限定されるものではない。 [Example]
Examples will be described below, but the present invention is not limited to the examples described below as long as the gist of the present invention is not exceeded.
　（実施例１）
　実施例１では、以下の手順で実施例１の電極群を作製した。 Example 1
In Example 1, the electrode group of Example 1 was produced according to the following procedure.
　＜正極の作製＞
　まず、スピネル型の結晶構造を有するマンガン酸リチウムの粉末と、コバルト酸リチウムの粉末とを準備した。スピネル型の結晶構造を有するマンガン酸リチウムは、式ＬｉＭｎ1.6Ａｌ0.4Ｏ4で表される組成を有していた。この式は、一般式ＬｉＭｎ2-xＭxＯ4において、ＭがＡｌでありx＝０．４である式に対応する。コバルト酸リチウムは、式ＬｉＣｏＯ2で表される組成を有していた。次いで、準備したスピネル型の結晶構造を有するマンガン酸リチウムの粉末と、コバルト酸リチウムの粉末とを、８０対２０の重量比率で混合し、混合物粉末を得た。この混合物粉末を正極活物質として用いた。 <Preparation of positive electrode>
First, a lithium manganate powder having a spinel crystal structure and a lithium cobaltate powder were prepared. Lithium manganate having a spinel crystal structure had a composition represented by the formula LiMn 1.6 Al 0.4 O 4 . This formula corresponds to the formula in which M is Al and x = 0.4 in the general formula LiMn 2-x M x O 4 . Lithium cobaltate had a composition represented by the formula LiCoO 2. Next, the prepared lithium manganate powder having a spinel crystal structure and the lithium cobaltate powder were mixed at a weight ratio of 80:20 to obtain a mixture powder. This mixture powder was used as a positive electrode active material.
　正極活物質としての活物質粉末と、導電剤としてのアセチレンブラックと、導電剤としてのグラファイトと、結着剤としてのポリフッ化ビニリデン（ＰＶｄＦ）とを、９１重量％：２．５重量％：３重量％：３．５重量％の重量割合で、Ｎ－メチルピロリドン（ＮＭＰ）に添加して混合し、スラリーを調製した。このスラリーを、厚さが１５μｍであるアルミニウム箔からなる集電体に片面の塗布量が７０ｇ／ｍ2となるように両面に塗布した。次いで、塗膜を乾燥させた。次いで、乾燥させた塗膜をプレスした。かくして、密度（集電体含まず）が２．８ｇ／ｃｍ3である正極材料層を有する正極を作製した。 91 wt%: 2.5 wt%: 3 of active material powder as a positive electrode active material, acetylene black as a conductive agent, graphite as a conductive agent, and polyvinylidene fluoride (PVdF) as a binder Weight%: A weight ratio of 3.5% by weight was added to N-methylpyrrolidone (NMP) and mixed to prepare a slurry. This slurry was applied to both sides of a current collector made of an aluminum foil having a thickness of 15 μm so that the coating amount on one side was 70 g / m 2 . Subsequently, the coating film was dried. Next, the dried coating film was pressed. Thus, a positive electrode having a positive electrode material layer having a density (not including a current collector) of 2.8 g / cm 3 was produced.
　＜負極の作製＞
　まず、スピネル型の結晶構造を有するチタン酸リチウムの粉末を準備した。スピネル型の結晶構造を有するチタン酸リチウムは、式Ｌｉ4Ｔｉ5Ｏ12で表される組成を有していた。 <Production of negative electrode>
First, lithium titanate powder having a spinel crystal structure was prepared. Lithium titanate having a spinel crystal structure had a composition represented by the formula Li 4 Ti 5 O 12 .
　負極活物質としてのスピネル型の結晶構造を有するチタン酸リチウム粉末と、導電剤としてのグラファイトと、導電剤としてのアセチレンブラックと、結着剤としてのＰＶｄＦとを、８５重量％：５重量％：３重量％：７重量％の重量割合でＮＭＰに添加して混合し、スラリーを調製した。続いて、このスラリーを厚さが１５μｍであるアルミニウム箔からなる集電体に、片面の塗布量が３０ｇ／ｍ2となるように両面に塗布した。次いで、塗膜を乾燥させた。次いで、乾燥させた塗膜をプレスした。かくして、密度（集電体含まず）が２．１ｇ／ｃｍ3である負極材料層を有する負極を作製した。 85 wt%: 5 wt% of lithium titanate powder having a spinel crystal structure as a negative electrode active material, graphite as a conductive agent, acetylene black as a conductive agent, and PVdF as a binder. A slurry was prepared by adding and mixing with NMP at a weight ratio of 3 wt%: 7 wt%. Subsequently, this slurry was applied to both sides of a current collector made of an aluminum foil having a thickness of 15 μm so that the coating amount on one side was 30 g / m 2 . Subsequently, the coating film was dried. Next, the dried coating film was pressed. Thus, a negative electrode having a negative electrode material layer having a density (not including a current collector) of 2.1 g / cm 3 was produced.
　＜セパレータの準備＞
　一方で、セパレータとしての、セルロース製の繊維を含む多孔質繊維シートを準備した。この多孔質繊維シートが含む繊維の平均幅は、３３μｍであった。この多孔質繊維シートの坪量は、８ｇ／ｍ2であった。この多孔質繊維シートの透地率は１８％であった。この多孔質繊維シートが含む細孔のうち、最も大きな細孔面積は、２０×１０-9ｍ2であった。この多孔質繊維シートの透気度は、０．１秒／１００ｍｌであった。この多孔質繊維シートの厚さは１５μｍであった。これらのパラメータは、多孔質繊維シートを測定装置の試料台上に固定させて測定したこと以外は先に説明した手順と同様の手順によって測定した。同様の多孔質繊維シートを、もう一枚のセパレータとして準備した。 <Preparation of separator>
On the other hand, the porous fiber sheet containing the fiber made from a cellulose as a separator was prepared. The average width of the fibers contained in this porous fiber sheet was 33 μm. The basis weight of this porous fiber sheet was 8 g / m 2 . The porosity of this porous fiber sheet was 18%. Among the pores included in this porous fiber sheet, the largest pore area was 20 × 10 −9 m 2 . The air permeability of this porous fiber sheet was 0.1 second / 100 ml. The thickness of this porous fiber sheet was 15 μm. These parameters were measured by the same procedure as described above, except that the measurement was performed with the porous fiber sheet fixed on the sample stage of the measuring apparatus. A similar porous fiber sheet was prepared as another separator.
　＜電極群の作製＞
　上記のようにして作製した正極と、先に説明した１枚のセパレータと、上記のようにして作製した負極と、先に説明したもう１枚のセパレータとを、この順序で積層し、積層体を得た。得られた積層体を、負極が最外周に位置するように渦巻き状に巻回して、巻回体を得た。この巻回体を９０℃で加熱プレスすることにより、偏平状電極群を作製した。かくして、実施例１の電極群が得られた。 <Production of electrode group>
The positive electrode manufactured as described above, the one separator described above, the negative electrode manufactured as described above, and the other separator described above are stacked in this order, and the laminate Got. The obtained laminate was wound in a spiral shape so that the negative electrode was located on the outermost periphery, to obtain a wound body. This wound body was heated and pressed at 90 ° C. to produce a flat electrode group. Thus, the electrode group of Example 1 was obtained.
　（実施例２～５及び比較例１～４）
　実施例２～５及び比較例１～４では、以下の表１に示すパラメータを有する多孔質繊維シートを用いたこと以外は、実施例１と同様の手順により、各実施例及び比較例の電極群を作製した。なお、各実施例及び比較例で用いた多孔質繊維シートは、セルロース製の繊維を含んでいた。また、各多孔質繊維シートは、以下の表１のパラメータを示すことができるように、先に説明した作製条件を複合的に調整して作製した。 (Examples 2 to 5 and Comparative Examples 1 to 4)
In Examples 2 to 5 and Comparative Examples 1 to 4, the electrodes of each Example and Comparative Example were prepared in the same procedure as Example 1 except that a porous fiber sheet having the parameters shown in Table 1 below was used. Groups were made. In addition, the porous fiber sheet used by each Example and the comparative example contained the fiber made from a cellulose. Moreover, each porous fiber sheet was produced by adjusting the production conditions described above in a composite manner so that the parameters shown in Table 1 below could be shown.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　（比較例５）
　以下の手順で負極を作製したこと以外は実施例１と同様の手順により、比較例５の電極群を作製した。 (Comparative Example 5)
An electrode group of Comparative Example 5 was produced by the same procedure as Example 1 except that the negative electrode was produced by the following procedure.
　負極活物質としてのグラファイトと、結着剤としてのＰＶｄＦとを、９５重量％：５重量％の重量割合でＮＭＰに添加して混合し、スラリーを調製した。続いて、このスラリーを厚さが１５μｍであるアルミニウム箔からなる集電体に、片面の塗布量が３０ｇ／ｍ2となるように両面に塗布した。次いで、塗膜を乾燥させた。次いで、乾燥させた塗膜をプレスした。かくして、密度（集電体含まず）が１．４ｇ／ｃｍ3である負極材料層を有する負極を作製した。 Graphite as a negative electrode active material and PVdF as a binder were added to NMP at a weight ratio of 95% by weight: 5% by weight and mixed to prepare a slurry. Subsequently, this slurry was applied to both sides of a current collector made of an aluminum foil having a thickness of 15 μm so that the coating amount on one side was 30 g / m 2 . Subsequently, the coating film was dried. Next, the dried coating film was pressed. Thus, a negative electrode having a negative electrode material layer having a density (not including a current collector) of 1.4 g / cm 3 was produced.
　［非水電解質電池の作製］
　以上のようにして作製した実施例１～５及び比較例１～５の各電極群を用いて、以下の手順により各非水電解質電池を作製した。なお、以下では単に「電極群」を用いたことを説明しているが、各実施例及び比較例のそれぞれの電極群を同様に用いて、各非水電解質電池を作製した。 [Preparation of non-aqueous electrolyte battery]
Using the electrode groups of Examples 1 to 5 and Comparative Examples 1 to 5 produced as described above, each nonaqueous electrolyte battery was produced by the following procedure. In the following description, it is described that the “electrode group” is simply used, but each non-aqueous electrolyte battery is manufactured using each electrode group of each example and comparative example in the same manner.
　［収納］
　電極群を外装部材としての外装缶に収納した。この外装缶の開口部に、注液口を備えた封口板を溶接した。注液口が開いた状態で、この外装缶の内部を、約９５℃で８時間真空乾燥に供した。 [Storage]
The electrode group was housed in an outer can as an outer member. A sealing plate having a liquid injection port was welded to the opening of the outer can. With the liquid injection port opened, the inside of the outer can was subjected to vacuum drying at about 95 ° C. for 8 hours.
　［非水電解液の調製］
　エチレンカーボネート（ＥＣ）とメチルエチルカーボネート（ＭＥＣ）とを体積比で１：２になるように混合して混合溶媒を調製した。この混合溶媒に、六フッ化リン酸リチウム（ＬｉＰＦ6）を１．０モル／Ｌの濃度で溶解し、非水電解液を調製した。 [Preparation of non-aqueous electrolyte]
Ethylene carbonate (EC) and methyl ethyl carbonate (MEC) were mixed at a volume ratio of 1: 2 to prepare a mixed solvent. In this mixed solvent, lithium hexafluorophosphate (LiPF 6 ) was dissolved at a concentration of 1.0 mol / L to prepare a non-aqueous electrolyte.
　［電池の作製］
　電極群を収容した外装缶内に、注液口より非水電解液を注入した。次いで、－９０ｋＰａの減圧環境下において、耐圧が０．４Ｍｐａ以上となるように注液口に仮封止を施した。かくして、電池ユニットが得られた。 [Production of battery]
A non-aqueous electrolyte was injected into the outer can containing the electrode group from the injection port. Next, the liquid inlet was temporarily sealed so that the pressure resistance was 0.4 Mpa or higher in a reduced pressure environment of −90 kPa. Thus, a battery unit was obtained.
　次いで、電池ユニットを、２５℃の環境下で、１Ｃレートで１３分間充電し、ＳＯＣ２０％の状態にした。次いで、電池ユニットを、６０℃環境下にて９０時間エージングに供した。エージング終了後、－９０ｋＰａの減圧環境下において、電池ユニットの仮封止を開放して、セル内のガス抜きを行った。次いで、注液口に本封止を施した。かくして、非水電解質電池を作製した。 Next, the battery unit was charged at a 1C rate for 13 minutes in an environment of 25 ° C. to obtain a SOC of 20%. Next, the battery unit was subjected to aging in a 60 ° C. environment for 90 hours. After the aging was completed, the temporary sealing of the battery unit was released under a reduced pressure environment of −90 kPa, and the cells were degassed. Subsequently, this sealing was given to the injection hole. Thus, a nonaqueous electrolyte battery was produced.
　［寿命試験］
　各非水電解質電池を、以下の手順で寿命試験に供した。 [Life test]
Each nonaqueous electrolyte battery was subjected to a life test according to the following procedure.
　まず、非水電解質電池を、２５℃の環境下で、１Ｃレートで定電流充電し、ＳＯＣ３０％に調整した。この状態の非水電解質電池の厚さＴa［ｍｍ］を測定した。なお、非水電解質電池の厚さＴaは、非水電解質電池の互いに直行する３つの方向における寸法のうち、最も小さい寸法とした。 First, the nonaqueous electrolyte battery was charged at a constant current at a 1C rate in an environment of 25 ° C., and adjusted to SOC 30%. The thickness Ta [mm] of the nonaqueous electrolyte battery in this state was measured. The thickness T a of the nonaqueous electrolyte battery is, among the dimensions in the three directions orthogonal to each other in a non-aqueous electrolyte battery was the smallest dimension.
　次いで、非水電解質電池を、６５℃環境下で１週間保存した。　
　次いで、非水電解質電池を恒温槽から取り出した。次いで、非水電解質電池の厚さＴb［ｍｍ］を測定した。ここでの厚さＴbは、試験前の厚さＴaと同じ方向の寸法を図ることによって測定した。 Next, the nonaqueous electrolyte battery was stored in a 65 ° C. environment for 1 week.
Subsequently, the nonaqueous electrolyte battery was taken out from the thermostat. Next, the thickness T b [mm] of the nonaqueous electrolyte battery was measured. Here thickness T b of the was determined by achieving the same dimension as the thickness T a of the previous test.
　試験後の電池厚さＴb［ｍｍ］の試験前の電池厚さＴa［ｍｍ］に対する比を、寿命性能指数として算出した。各非水電解質電池についての寿命性能指数を、以下の表２に示す。 The ratio of the battery thickness T b [mm] after the test to the battery thickness T a [mm] before the test was calculated as a life performance index. The life performance index for each non-aqueous electrolyte battery is shown in Table 2 below.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　［評価］
　表２に示した結果から明らかなように、実施例１～５の非水電解質電池は、比較例１、２及び４の非水電解質電池のそれよりも低い寿命性能指数を示した。寿命性能指数が小さいほど、試験前後での厚みの増分が小さく、ガス発生量が少ないことを意味する。よって、寿命性能指数が小さいほど、ガス発生をより十分に抑えることができた非水電解質電池であるということができる。従って、表２に示した結果から、実施例１～５の非水電解質電池は、比較例１、２及び４の非水電解質電池よりも、ガス発生をより十分に抑えることができたことが分かる。 [Evaluation]
As is apparent from the results shown in Table 2, the nonaqueous electrolyte batteries of Examples 1 to 5 exhibited a life performance index lower than that of the nonaqueous electrolyte batteries of Comparative Examples 1, 2, and 4. It means that the smaller the life performance index, the smaller the increase in thickness before and after the test, and the smaller the amount of gas generated. Therefore, it can be said that it is a nonaqueous electrolyte battery in which gas generation can be more sufficiently suppressed as the life performance index is smaller. Therefore, from the results shown in Table 2, the nonaqueous electrolyte batteries of Examples 1 to 5 were able to suppress the gas generation more sufficiently than the nonaqueous electrolyte batteries of Comparative Examples 1, 2, and 4. I understand.
　比較例３及び５の各非水電解質電池は、正極と負極との間で電気的短絡が生じてしまい、電池として機能することができなかった。比較例３では、電極群が含むセパレータの透地率が高過ぎたため、電気的短絡が生じたと考えられる。比較例５では、充放電により負極上にリチウムデンドライトが析出し、これが多孔質繊維シートを貫通し、正極と負極との間の電気的短絡をもたらしたと考えられる。 Each of the nonaqueous electrolyte batteries of Comparative Examples 3 and 5 could not function as a battery because an electrical short circuit occurred between the positive electrode and the negative electrode. In Comparative Example 3, it is considered that an electrical short circuit occurred because the permeability of the separator included in the electrode group was too high. In Comparative Example 5, it is considered that lithium dendrite was deposited on the negative electrode due to charge / discharge, which penetrated the porous fiber sheet and caused an electrical short circuit between the positive electrode and the negative electrode.
　比較例１、２及び４の非水電解質電池がガス発生を十分に抑制できなかったのは、各比較例の電極群のセパレータの透地率が１０％未満であったこと（比較例１及び２）及び／又は多孔質繊維シートが８×１０-9ｍ2以上の細孔面積を有する細孔を含まなかったこと（比較例１及び４）が原因であると考えられる。 The reason why the nonaqueous electrolyte batteries of Comparative Examples 1, 2, and 4 were not able to sufficiently suppress gas generation was that the permeability of the separator of the electrode group of each Comparative Example was less than 10% (Comparative Examples 1 and 2) and / or that the porous fiber sheet did not contain pores having a pore area of 8 × 10 −9 m 2 or more (Comparative Examples 1 and 4).
　以上に説明した１つ以上の実施形態及び実施例によると、電極群が提供される。この電極群は、正極と、負極と、少なくとも正極と負極との間に配置されたセパレータとを具備する。セパレータの透地率は１０％以上２０％以下である。セパレータは、細孔面積が８×１０-9ｍ2以上である細孔と繊維とを含む多孔質繊維シートを含む。この電極群は、正極と負極とが向き合った方向における流体の移動を促進することができる。また、負極がリチウムチタン複合酸化物を含む。これらの結果、この電極群は、ガス発生を十分に抑えることができる非水電解質電池を実現することができる。 According to one or more embodiments and examples described above, an electrode group is provided. The electrode group includes a positive electrode, a negative electrode, and a separator disposed at least between the positive electrode and the negative electrode. The separator has a permeability of 10% or more and 20% or less. The separator includes a porous fiber sheet including pores having a pore area of 8 × 10 −9 m 2 or more and fibers. This electrode group can promote the movement of fluid in the direction in which the positive electrode and the negative electrode face each other. The negative electrode includes a lithium titanium composite oxide. As a result, this electrode group can realize a non-aqueous electrolyte battery that can sufficiently suppress gas generation.
　本発明のいくつかの実施形態を説明したが、これらの実施形態は、例として提示したものであり、発明の範囲を限定することは意図していない。これら新規な実施形態は、その他の様々な形態で実施されることが可能であり、発明の要旨を逸脱しない範囲で、種々の省略、置き換え、変更を行うことができる。これら実施形態やその変形は、発明の範囲や要旨に含まれるとともに、特許請求の範囲に記載された発明とその均等の範囲に含まれる。 Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

Claims (7)

  1. 　正極と、
    　リチウムチタン複合酸化物を含む負極と、
    　少なくとも前記正極と前記負極との間に配置されたセパレータと
    を具備し、
    　前記セパレータは、透地率が１０％以上２０％以下であり、細孔面積が８×１０-9ｍ2以上である細孔と繊維とを含む多孔質繊維シートを含む電極群。     A positive electrode;
    A negative electrode comprising a lithium titanium composite oxide;
    Comprising at least a separator disposed between the positive electrode and the negative electrode;
    The separator is an electrode group including a porous fiber sheet including pores and fibers having a permeability of 10% or more and 20% or less and a pore area of 8 × 10 −9 m 2 or more.
  2. 　前記繊維の平均幅が１０μｍ以上４０μｍ以下である請求項１に記載の電極群。 The electrode group according to claim 1, wherein the average width of the fibers is 10 μm or more and 40 μm or less.
  3. 　前記多孔質繊維シートの坪量が５ｇ／ｍ2以上２０ｇ／ｍ2以下である請求項１又は２に記載の電極群。 The electrode group according to claim 1 or 2, wherein a basis weight of the porous fiber sheet is 5 g / m 2 or more and 20 g / m 2 or less.
  4. 　前記多孔質繊維シートは、直径が５０μｍ以上である細孔を含む請求項１～３の何れか１項に記載の電極群。 4. The electrode group according to claim 1, wherein the porous fiber sheet includes pores having a diameter of 50 μm or more.
  5. 　前記正極は、多孔質の正極材料層を具備し、
    　前記負極は、多孔質の負極材料層を具備し、前記負極材料層が前記リチウムチタン複合酸化物を含み、
    　前記セパレータは、少なくとも前記正極材料層と前記負極材料層との間に配置されている請求項１～４の何れか１項に記載の電極群。     The positive electrode comprises a porous positive electrode material layer,
    The negative electrode comprises a porous negative electrode material layer, the negative electrode material layer includes the lithium titanium composite oxide,
    The electrode group according to any one of claims 1 to 4, wherein the separator is disposed at least between the positive electrode material layer and the negative electrode material layer.
  6. 　請求項１～５の何れか１項に記載の電極群と、
    　非水電解質と
    を具備する非水電解質電池。     An electrode group according to any one of claims 1 to 5;
    A non-aqueous electrolyte battery comprising a non-aqueous electrolyte.
  7. 　請求項６に記載の非水電解質電池を具備する電池パック。 A battery pack comprising the nonaqueous electrolyte battery according to claim 6.
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CN111129400A (en) * 2019-12-31 2020-05-08 武汉惠强新能源材料科技有限公司 Preparation process of porous lithium battery diaphragm

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