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WO2019003835A1 - Accumulateur au lithium-ion - Google Patents

Accumulateur au lithium-ion Download PDF

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Publication number
WO2019003835A1
WO2019003835A1 PCT/JP2018/021665 JP2018021665W WO2019003835A1 WO 2019003835 A1 WO2019003835 A1 WO 2019003835A1 JP 2018021665 W JP2018021665 W JP 2018021665W WO 2019003835 A1 WO2019003835 A1 WO 2019003835A1
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WIPO (PCT)
Prior art keywords
positive electrode
active material
electrode active
secondary battery
lithium ion
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PCT/JP2018/021665
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English (en)
Japanese (ja)
Inventor
優一郎 橋爪
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Murata Manufacturing Co Ltd
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Murata Manufacturing Co Ltd
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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
    • 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
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0569—Liquid materials characterised by the solvents
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present invention relates to a lithium ion secondary battery.
  • the secondary battery has a structure in which a positive electrode, a negative electrode, a separator disposed between the positive electrode and the negative electrode, and an electrolyte are enclosed in an outer package.
  • lithium ions move between the positive electrode and the negative electrode through the electrolyte to charge and discharge the battery.
  • Patent Document 1 sets the proportion of the total volume of pores having a diameter of 2 ⁇ m or less in the total pore volume to 45 vol% or more in the positive electrode active material layer, and is measured by a mercury porosimeter Discloses a technique for setting the value of the degree of pore inflection to 2.216 or less.
  • the inventors of the present invention have found that the following new problems occur in conventional lithium ion secondary batteries: (1) It is difficult to achieve a pore curvature of 2.216 or less because it is necessary to densify the positive electrode active material layer from the recent demand for higher energy density of lithium ion secondary batteries. And (2) Even if the degree of pore inflection of 2.216 or less is achieved, the skeleton portion as the electron path constituting the pore is significantly reduced, so that the rate characteristic is deteriorated (the electron path is an electron It is the way to go).
  • a method of increasing the cell voltage can be considered.
  • the charging upper limit voltage is increased to 4.41 V or more
  • the rate characteristic is further deteriorated.
  • the positive electrode potential quickly reaches the upper limit potential during charging, and the time during which the positive electrode is maintained in a severe oxidizing atmosphere It became longer and accelerated the deterioration of the life.
  • An object of the present invention is to provide a lithium ion secondary battery having better rate characteristics even when the charging upper limit voltage is increased to 4.41 V or more.
  • the present invention A lithium ion secondary battery comprising a positive electrode, a negative electrode, a separator disposed between the positive electrode and the negative electrode, and a non-aqueous electrolyte, and having a charge upper limit voltage of 4.41 V or higher,
  • the positive electrode relates to a lithium ion secondary battery having a positive electrode active material layer having a pore curvature of 7 or more and 60 or less measured by a mercury porosimeter.
  • the lithium ion secondary battery of the present invention exhibits better rate characteristics even when the charging upper limit voltage is increased to 4.41 V or more.
  • the present invention provides a lithium ion secondary battery.
  • lithium ion secondary battery refers to a battery that can be repeatedly charged and discharged by the transfer of electrons by lithium ions. Therefore, the “lithium ion secondary battery” is not excessively limited to the name, and may include, for example, “lithium ion storage device” and the like.
  • the lithium ion secondary battery of the present invention (hereinafter sometimes referred to simply as “secondary battery”) has a charge upper limit voltage of 4.41 V or more, preferably 4.43 V or more, preferably 4.45 V or more, more preferably 4.47V or more.
  • the upper limit value of the charging upper limit voltage is not particularly limited, and may be, for example, 4.80 V, 4.70 V, 4.60 V, or 4.50 V. By setting the charging upper limit voltage in the above range, the capacity per weight of the active material of the positive electrode can be increased, and as a result, the energy density of the secondary battery can be improved.
  • the charge upper limit voltage is an upper limit voltage at the time of charge, which is designed in advance based on the capacity of the secondary battery, and is also referred to as a “charge termination voltage”, which is one of the specifications of the secondary battery.
  • the secondary battery of the present invention includes a positive electrode, a negative electrode, a separator disposed between the positive electrode and the negative electrode, and a non-aqueous electrolyte.
  • the secondary battery of the present invention is usually constructed by enclosing an electrode assembly composed of a positive electrode, a negative electrode and a separator and a non-aqueous electrolyte in an outer package.
  • the positive electrode has at least a positive electrode active material layer.
  • the positive electrode is usually composed of a positive electrode active material layer and a positive electrode current collector (foil), and a positive electrode active material layer is provided on at least one side of the positive electrode current collector.
  • a positive electrode active material layer may be provided on both sides of the positive electrode current collector, or a positive electrode active material layer may be provided on one side of the positive electrode current collector.
  • the positive electrode is preferably provided with a positive electrode active material layer on both sides of the positive electrode current collector.
  • the secondary battery usually includes a plurality of positive electrodes, and one or more positive electrodes provided with a positive electrode active material layer on both sides of the positive electrode current collector, and a positive electrode active material layer provided on one side of the positive electrode current collector. It may include one or more positive electrodes.
  • the positive electrode active material layer has a porosity of 7 or more and 60 or less, and preferably 8 or more and 55 or less, and more preferably 10 or more and 40 or less from the viewpoint of further improvement of rate characteristics under high voltage. More preferably, it is 10 or more and 20 or less.
  • the positive electrode active material layer has the above-mentioned pore curvilinearity, the electron path can be effectively secured while the migration distance of lithium ions is sufficiently shortened in the secondary battery. As a result, even if the charging upper limit voltage is increased, better rate characteristics can be obtained.
  • the pore curvature is too large, the migration distance of lithium ions becomes extremely long, and the rate characteristics deteriorate.
  • the rate characteristic is a characteristic that can be sufficiently discharged even if the discharge current is increased.
  • the rate characteristic under high voltage means that when the charge upper limit voltage is relatively high as described above.
  • the pore curvature is one parameter that indicates the degree of pore meandering.
  • the pore curve factor is a value measured by a measuring apparatus “Autopore IV 9500” (manufactured by Shimadzu Corporation) based on a mercury porosimeter.
  • the density of the positive electrode active material layer is usually 2.0 g / cm 3 or more and 5.0 g / cm 3 or less, and preferably 3.0 g / cm 3 or more from the viewpoint of further improvement of rate characteristics under high voltage. .5g / cm 3 or less, and more preferably not more than 3.2 g / cm 3 or more 4.1 g / cm 3, more preferably less 3.5 g / cm 3 or more 4.0 g / cm 3, most Preferably, they are 3.4 g / cm 3 or more and 3.7 g / cm 3 or less.
  • the density of the positive electrode active material layer is a value calculated by dividing the mass of the layer by the volume of the layer.
  • the mass of the positive electrode active material layer can be determined by weighing the positive electrode active material layer peeled off from the positive electrode current collector.
  • the thickness of the positive electrode active material layer is calculated by subtracting the thickness of the positive electrode current collector from the thickness of the positive electrode, and calculating the thickness of the positive electrode active material layer. The product of the thickness of the positive electrode active material layer and the formation area of the positive electrode active material layer It can be obtained from
  • the positive electrode active material layer contains a positive electrode active material, and usually further contains a binder and a conductive aid.
  • the positive electrode active material is usually in the form of particles, and a binder is contained in the positive electrode active material layer for sufficient contact between particles and shape retention.
  • a conductive support agent be included in the positive electrode active material layer in order to facilitate the transfer of electrons for promoting the cell reaction.
  • the positive electrode active material is a material directly involved in the delivery of electrons in the secondary battery, and is a main material of the positive electrode responsible for charge and discharge, that is, battery reaction. More specifically, ions are provided to the electrolyte due to "the positive electrode active material contained in the positive electrode active material layer", and such ions move between the positive electrode and the negative electrode to deliver electrons. Charge and discharge are made.
  • the positive electrode active material layer is particularly a layer capable of inserting and extracting lithium ions. Lithium ions move between the positive electrode and the negative electrode through the electrolyte to charge and discharge the battery.
  • the positive electrode active material is not particularly limited as long as it contributes to absorption and release of lithium ions, and is preferably, for example, a lithium-containing composite oxide.
  • the lithium-containing composite oxide is usually a lithium transition metal composite oxide.
  • the transition metal may be any transition metal (transition element), and examples thereof include a first transition element, a second transition element and a third transition element.
  • the preferred transition metal is the first transition element.
  • the positive electrode active material is a group consisting of lithium, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper and zinc (especially cobalt, nickel, and the like) from the viewpoint of further improvement of rate characteristics under high voltage. It is preferable that it is a lithium transition metal complex oxide containing at least one transition metal selected from the group consisting of manganese and iron). As a specific example of such a lithium transition metal composite oxide, for example, lithium cobaltate, lithium nickelate, lithium manganate, lithium iron phosphate, or those in which part of their transition metals is replaced with another metal (Especially doped).
  • Another metal includes, for example, one or more metals selected from the group consisting of aluminum, magnesium, zirconium, nickel, manganese and titanium. From the viewpoint of further improving the rate characteristics under high voltage, the positive electrode active material preferably contains lithium cobaltate.
  • Lithium cobaltate is a compound represented by the chemical formula of LiCoO 2 and, from the viewpoint of further improvement of rate characteristics under high voltage, lithium cobaltate in which a part of cobalt is replaced with another metal (especially doped) preferable.
  • Other metals (doped metals) include, for example, similar metals exemplified as the above-mentioned other metals (doped metals).
  • the substitution amount (doping amount) is usually 0.001 parts by weight or more and 10 parts by weight or less, preferably 0.01 parts by weight or more and 7 parts by weight or less, based on 100 parts by weight of cobalt in lithium cobalt oxide.
  • the substitution amount (doping amount) of each metal may be within the above range.
  • the average particle diameter D50 of the positive electrode active material is usually 5 ⁇ m to 30 ⁇ m, preferably 10 ⁇ m to 25 ⁇ m, and more preferably 8 ⁇ m to 20 ⁇ m from the viewpoint of further improvement of rate characteristics under high voltage. .
  • the average particle diameter D50 a value measured by a laser diffraction type particle size distribution measuring apparatus (LA960 manufactured by Horiba, Ltd.) is used.
  • the specific surface area of the positive electrode active material is usually less 0.01 m 2 / g or more 10 m 2 / g, from the viewpoint of further improvement in the rate characteristics under high voltage, preferably 0.05 m 2 / g or more 5 m 2 / It is g or less, more preferably 0.1 m 2 / g or more and 1 m 2 / g or less.
  • the specific surface area is a value measured by a specific surface area measuring device (Macsorb manufactured by Mountech).
  • the positive electrode active material can be obtained as a commercially available product, or can be produced by a known method.
  • the manufacturing method of a well-known inorganic compound can be used.
  • the positive electrode active material can be manufactured by measuring a plurality of compounds as raw materials to have a desired composition ratio, mixing uniformly, and firing.
  • a compound used as a raw material a lithium containing compound, a transition element containing compound, a typical element containing compound, and an anion containing compound are mentioned, for example.
  • a lithium containing compound for example, hydroxide, chloride, nitrate and carbonate of lithium can be used.
  • transition element-containing compound for example, oxides, hydroxides, chlorides, nitrates, carbonates, sulfates and organic acid salts of transition elements can be used.
  • the transition element-containing compound when the transition elements are Co, Mn and Fe, for example, manganese dioxide, ⁇ -MnOOH, manganese carbonate, manganese nitrate, manganese hydroxide, Co 3 O 4 , CoO, Fe 2 O 3 And Fe 3 O 4 and the like.
  • typical element-containing compound for example, oxides, hydroxides, chlorides, nitrates, carbonates, sulfates and organic acid salts of typical elements can be used.
  • an anion containing compound when an anion is a fluorine, lithium fluoride etc. can be used, for example.
  • the firing temperature is usually 400 ° C. or more and 1200 ° C. or less.
  • the firing may be performed in the air, in a vacuum, in an oxygen atmosphere, in a hydrogen atmosphere, or in an inert gas atmosphere such as nitrogen and a rare gas.
  • the content of the positive electrode active material is usually 90% by weight to 99% by weight, preferably 95% by weight to 99% by weight, based on the total weight (solid content) of the positive electrode active material layer.
  • the positive electrode active material layer may contain two or more positive electrode active materials, in which case the total content thereof may be in the above range.
  • the binder which may be contained in the positive electrode active material layer is not particularly limited.
  • the binder of the positive electrode active material layer is, for example, polyvinylidene fluoride (PVdF), vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, polytetrafluoroethylene or the like At least one selected from the group can be mentioned.
  • the binder of the positive electrode active material layer preferably contains polyvinylidene fluoride (PVdF) from the viewpoint of further improving the rate characteristics under high voltage.
  • the content of the binder in the positive electrode active material layer is usually 0.1% by weight or more and 5% by weight or less based on the total weight (solid content weight) of the positive electrode active material layer, and the rate characteristic at high voltage is further increased. From the viewpoint of improvement, it is preferably 0.5% by weight or more and 3% by weight or less, more preferably 0.5% by weight or more and 2% by weight or less.
  • the positive electrode active material layer may contain two or more binders, in which case the total content thereof may be in the above range.
  • the conductive aid of the positive electrode active material layer preferably contains carbon fibers (particularly carbon nanotubes) from the viewpoint of further improvement of rate characteristics under high voltage.
  • the average diameter of carbon fibers is usually 1 nm or more and 20 nm or less, preferably 2 nm or more and 12 nm or less.
  • the average chain length of carbon fibers (especially carbon nanotubes) is usually 50 nm or more and 400 nm or less, preferably 100 nm or more and 300 nm or less.
  • the mean diameter and mean chain length are the mean values of any 100 carbon fibers.
  • the content of the conductive additive in the positive electrode active material layer is usually 0.1% by weight or more and 5% by weight or less based on the total weight (solid content weight) of the positive electrode active material layer, and the rate characteristics at high voltage Preferably, it is 0.5% by weight or more and 2% by weight or less.
  • the positive electrode active material layer may contain two or more conductive aids, in which case the total content thereof may be in the above range.
  • the positive electrode active material layer is obtained, for example, by applying a positive electrode slurry obtained by dispersing the positive electrode active material and optionally added binder and conductive auxiliary agent in a solvent and drying it on a positive electrode current collector, Can be obtained.
  • a positive electrode slurry obtained by dispersing the positive electrode active material and optionally added binder and conductive auxiliary agent in a solvent and drying it on a positive electrode current collector, Can be obtained.
  • the solvent of the positive electrode slurry is not particularly limited, and usually, a solvent capable of dissolving the binder is used.
  • the solvent for the positive electrode slurry include organic solvents such as N-methylpyrrolidone, toluene, tetrahydrofuran, cyclohexane, methyl ethyl ketone and the like, and water.
  • the single-sided coating amount (after drying) of the positive electrode slurry is usually 1 mg / cm 2 or more and 40 mg / cm 2 or less, preferably 10 mg / cm 2 or more and 30 mg / cm 2 or less.
  • the positive electrode active material and the binder in the positive electrode active material layer are a combination of lithium cobaltate and polyvinylidene fluoride.
  • the positive electrode current collector used for the positive electrode is a member that contributes to collecting or supplying electrons generated in the positive electrode active material due to the cell reaction.
  • a positive electrode current collector may be a sheet-like metal member, and may have a porous or perforated form.
  • the positive electrode current collector may be metal foil, punching metal, netting, expanded metal or the like.
  • the positive electrode current collector used for the positive electrode is preferably made of a metal foil containing at least one selected from the group consisting of aluminum, stainless steel, nickel and the like, and may be, for example, an aluminum foil.
  • the negative electrode has at least a negative electrode active material layer.
  • the negative electrode is usually composed of a negative electrode active material layer and a negative electrode current collector (foil), and a negative electrode active material layer is provided on at least one side of the negative electrode current collector.
  • the negative electrode active material layer may be provided on both sides of the negative electrode current collector, or the negative electrode active material layer may be provided on one side of the negative electrode current collector. From the viewpoint of further increasing the capacity of the secondary battery, it is preferable that a negative electrode active material layer is provided on both sides of the negative electrode current collector.
  • the secondary battery usually includes a plurality of negative electrodes, and one or more negative electrodes provided with a negative electrode active material layer on both sides of the negative electrode collector, and a negative electrode active material layer provided on one side of the negative electrode collector.
  • One or more negative electrodes may be included.
  • the negative electrode active material layer contains a negative electrode active material, and usually further contains a binder and a conductive auxiliary as in the case of the positive electrode active material layer.
  • the negative electrode active material is usually in the form of particles, and a binder is contained in the negative electrode active material layer for sufficient contact between particles and shape retention.
  • a conductive support agent be included in the negative electrode active material layer in order to facilitate the transfer of electrons for promoting the cell reaction.
  • the negative electrode active material contained in the negative electrode material layer is also a substance directly involved in the delivery of electrons in the secondary battery, and carries out charge / discharge, that is, the negative electrode Is the main substance of More specifically, ions are provided to the electrolyte due to the “negative electrode active material contained in the negative electrode active material layer”, and the ions move between the positive electrode and the negative electrode to deliver electrons. Charge and discharge are made.
  • the negative electrode layer is particularly a layer capable of inserting and extracting lithium ions.
  • the negative electrode active material is not particularly limited as long as it contributes to absorption and release of lithium ions, and, for example, various carbon materials, oxides, lithium alloys, silicon, silicon alloys, tin alloys and the like are preferable.
  • the negative electrode active material is preferably a carbon material from the viewpoint of further improving the rate characteristics at high voltage.
  • carbon materials of the negative electrode active material for example, graphite (for example, natural graphite, artificial graphite, MCMB (meso carbon micro beads), non-graphitizable carbon, graphitizable carbon), hard carbon, soft carbon, diamond-like Carbon etc.
  • graphite is preferable in that it has high electron conductivity and excellent adhesion to the negative electrode current collector.
  • oxide of the negative electrode active material include at least one selected from the group consisting of silicon oxide [SiO x (0.5 ⁇ x ⁇ 1.5)], tin oxide, indium oxide, zinc oxide, lithium oxide and the like. be able to.
  • the lithium alloy of the negative electrode active material may be any metal that can be alloyed with lithium, for example, Al, Si, Pb, Sn, In, Bi, Ag, Ba, Ca, Hg, Pd, Pt, Te, Zn, It may be a binary, ternary or higher alloy of a metal such as La and lithium. Such oxides and lithium alloys are preferably amorphous as their structural forms. This is because deterioration due to nonuniformity such as grain boundaries or defects is less likely to occur. From the viewpoint of further improving the rate characteristics under high voltage, the negative electrode active material preferably contains a carbon material, and more preferably contains graphite (in particular, artificial graphite).
  • the average particle diameter D50 of the negative electrode active material is usually 5 ⁇ m to 30 ⁇ m, preferably 10 ⁇ m to 25 ⁇ m, and more preferably 12 ⁇ m to 20 ⁇ m from the viewpoint of further improvement of rate characteristics under high voltage .
  • the specific surface area of the negative electrode active material is usually less 0.1 m 2 / g or more 10 m 2 / g, from the viewpoint of further improvement in rate characteristics at high voltages, preferably 0.5 m 2 / g or more 5 m 2 / It is g or less, more preferably 1 m 2 / g or more and 5 m 2 / g or less.
  • the content of the negative electrode active material is usually 90% by weight to 99% by weight, preferably 95% by weight to 99% by weight, based on the total weight (solid content) of the negative electrode active material layer.
  • the negative electrode active material layer may contain two or more negative electrode active materials, in which case the total content thereof may be in the above range.
  • the binder which may be contained in the negative electrode active material layer is not particularly limited.
  • the binder of the negative electrode active material layer include at least one selected from the group consisting of styrene butadiene rubber (SBR), polyacrylic acid, polyvinylidene fluoride (PVdf), polyimide resins and polyamideimide resins.
  • SBR styrene butadiene rubber
  • PVdf polyacrylic acid
  • PVdf polyvinylidene fluoride
  • polyimide resins polyimide resins
  • polyamideimide resins polyamideimide resins
  • the content of the binder in the negative electrode active material layer is usually 0.1% by weight or more and 5% by weight or less based on the total weight (solid content weight) of the positive electrode active material layer, and further the rate characteristics at high voltage From the viewpoint of improvement, it is preferably 0.5% by weight or more and 3% by weight or less, more preferably 1% by weight or more and 3% by weight or less.
  • the negative electrode active material layer may contain two or more binders, in which case the total content thereof may be in the above range.
  • the conductive aid that may be included in the negative electrode active material layer.
  • the conductive aid for the negative electrode active material layer include carbon blacks such as thermal black, furnace black, channel black, ketjen black and acetylene black, carbon fibers such as carbon nanotubes and vapor grown carbon fibers, copper, nickel, Examples thereof include at least one selected from the group consisting of metal powders such as aluminum and silver, and polyphenylene derivatives.
  • the content of the conductive auxiliary in the negative electrode active material layer is usually 0.1% by weight or more and 5% by weight or less, preferably 0.5% by weight, based on the total weight (solid content weight) of the negative electrode active material layer. More than 2% by weight.
  • the negative electrode active material layer may contain two or more conductive aids, in which case the total content thereof may be in the above range.
  • a conductive support agent is not normally used.
  • the negative electrode active material layer may contain a thickener.
  • a thickener a carboxymethylcellulose (CMC) etc. are mentioned, for example.
  • the content of the thickener in the negative electrode active material layer is usually 0.1% by weight or more and 5% by weight or less, preferably 0.5% by weight, based on the total weight (solid content weight) of the negative electrode active material layer. More than 2% by weight.
  • the negative electrode active material layer may contain two or more thickeners, in which case the total content thereof may be in the above range.
  • the negative electrode active material layer is obtained by, for example, applying a negative electrode slurry obtained by dispersing a negative electrode active material and optionally added binder, a conductive auxiliary agent, and a thickener in a solvent and drying it on a negative electrode current collector. It can be obtained by consolidation using a machine or the like.
  • the solvent of the negative electrode slurry is not particularly limited, and the same solvent exemplified as the solvent of the positive electrode slurry may be mentioned.
  • the single-sided coating amount (after drying) of the negative electrode slurry is usually 1 mg / cm 2 or more and 40 mg / cm 2 or less, preferably 5 mg / cm 2 or more and 20 mg / cm 2 or less.
  • the negative electrode current collector used for the negative electrode is a member that contributes to collecting or supplying the electrons generated in the positive electrode active material due to the battery reaction.
  • a current collector may be a sheet-like metal member, and may have a porous or perforated form.
  • the negative electrode current collector may be a metal foil, a punching metal, a net, an expanded metal, or the like, similarly to the positive electrode current collector.
  • the negative electrode current collector used for the negative electrode is preferably made of a metal foil containing at least one selected from the group consisting of copper, stainless steel, nickel and the like, and may be, for example, a copper foil.
  • the negative electrode active material and the binder in the negative electrode active material layer are a combination of artificial graphite and styrene butadiene rubber.
  • the separator is not particularly limited as long as ions can pass while preventing electrical contact between the positive electrode and the negative electrode.
  • the material which comprises a separator is not specifically limited as long as the electrical contact between a positive electrode and a negative electrode can be prevented,
  • an electrically insulating polymer etc. are mentioned.
  • the electrically insulating polymer include polyolefins, polyesters, polyimides, polyamides, and polyamideimides.
  • the separator is a porous or microporous insulating member and has a membrane morphology due to its small thickness.
  • a microporous polyolefin membrane may be used as a separator.
  • the microporous membrane used as the separator contains, for example, only polyethylene (PE) or only polypropylene (PP) as the polyolefin.
  • the separator is a laminate composed of “PE microporous membrane” and “PP microporous membrane”.
  • the surface of the separator may be covered with an inorganic particle coat layer and / or an adhesive layer or the like.
  • the surface of the separator may have adhesiveness.
  • Nonaqueous electrolyte assists in the movement of lithium ions released from the electrodes (positive and negative electrodes).
  • Nonaqueous electrolytes include nonaqueous solvents and electrolyte salts.
  • the non-aqueous electrolyte may have a form such as liquid or gel (note that, in the present specification, the "liquid” non-aqueous electrolyte is also referred to as "non-aqueous electrolyte solution").
  • the non-aqueous solvent of the non-aqueous electrolyte is not particularly limited.
  • at least one selected from the group consisting of carbonate solvents, ester solvents, sultone solvents, nitrile solvents, and the like, and fluorinated compounds thereof Can be mentioned.
  • the non-aqueous electrolyte preferably contains a carbonate-based solvent as a non-aqueous solvent, more preferably a carbonate-based solvent and an ester-based solvent, and still more preferably a carbonate-based solvent from the viewpoint of further improvement of rate characteristics under high voltage. It contains a solvent system, an SL solvent and a sultone solvent, and most preferably a carbonate solvent, an ester solvent, a sultone solvent and a nitrile solvent.
  • the carbonate solvent contains cyclic carbonates and / or linear carbonates, and preferably contains cyclic carbonates and linear carbonates from the viewpoint of further improvement of rate characteristics under high voltage.
  • cyclic carbonates include at least one selected from the group consisting of propylene carbonate (PC), ethylene carbonate (EC), fluoroethylene carbonate (FEC), butylene carbonate (BC) and vinylene carbonate (VC).
  • PC propylene carbonate
  • EC ethylene carbonate
  • FEC fluoroethylene carbonate
  • BC butylene carbonate
  • VC vinylene carbonate
  • the linear carbonates include at least one selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC) and dipropyl carbonate (DPC).
  • the content of the carbonate-based solvent is usually 10% by volume or more based on the non-aqueous solvent of the non-aqueous electrolyte, and from the viewpoint of further improvement of rate characteristics under high voltage, preferably 20% by volume or more and 90% by volume
  • the content is preferably 30% by volume or more and 80% by volume or less.
  • the volume ratio of cyclic carbonates to linear carbonates is usually 1/9 or more and 9/1 or less From the viewpoint of further improvement of rate characteristics under high voltage, it is preferably 2/8 or more and 7/3 or less, and more preferably 3/7 or more and 6/4 or less.
  • ester solvent for example, methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate (PP), methyl butyrate at least selected from the group consisting of One can be mentioned.
  • the content of the ester-based solvent is usually 70% by volume or less based on the non-aqueous solvent of the non-aqueous electrolyte, and from the viewpoint of further improvement of rate characteristics under high voltage, preferably 5% by volume to 60% by volume
  • the content is preferably 10% by volume or more and 50% by volume or less.
  • a sultone solvent for example, at least one selected from the group consisting of propane sultone (PS) and propene sultone can be mentioned.
  • the content of the sultone-based solvent is usually 90% by volume or less based on the non-aqueous solvent of the non-aqueous electrolyte, and preferably from 1% by volume to 60% by volume from the viewpoint of further improvement of rate characteristics under high voltage
  • the amount is preferably 2% by volume or more and 50% by volume or less.
  • nitrile solvents include at least one selected from the group consisting of adiponitrile (ADN), succinonitrile, suberonitrile, acetonitrile, glutaronitrile, methoxyacetonitrile, 3-methoxypropionitrile.
  • ADN adiponitrile
  • succinonitrile succinonitrile
  • suberonitrile acetonitrile
  • glutaronitrile methoxyacetonitrile
  • methoxyacetonitrile 3-methoxypropionitrile.
  • the content of the nitrile solvent is usually 10% by volume or less with respect to the non-aqueous solvent of the non-aqueous electrolyte, and from the viewpoint of further improving the rate characteristics under high voltage, preferably 0.5% by volume or more. It is the volume% or less, more preferably 1 volume% or more and 5 volume% or less.
  • electrolyte salts of non-aqueous electrolytes include LiPF 6 , LiBF 4 , LiClO 4 , LiCF 3 SO 3 , Li (CF 3 SO 2 ) 2 N, Li (C 2 F 5 SO 2 ) 2 N, Li (CF 2 ) 3 ) Li salts such as 2 N and LiB (CN) 4 are preferably used.
  • the concentration of the electrolyte salt in the non-aqueous electrolyte is not particularly limited, and may be, for example, 0.1 mol / L or more and 10 mol / L or less, preferably from the viewpoint of further improvement of rate characteristics under high voltage. .5 mol / L or more and 2 mol / L or less.
  • the secondary battery can be manufactured by enclosing an electrode assembly comprising a positive electrode, a negative electrode and a separator and a non-aqueous electrolyte in an outer package.
  • an electrode assembly comprising a positive electrode, a negative electrode and a separator and a non-aqueous electrolyte in an outer package.
  • positive electrodes and negative electrodes are alternately disposed via a separator.
  • the structure of the electrode assembly is not particularly limited.
  • the electrode assembly may have a planar laminated structure in which a plurality of electrode units (electrode constituent layers) including a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode are stacked in a planar manner.
  • the structure of the electrode assembly is a wound structure (jelly roll type) in which an electrode unit (electrode constituent layer) including a positive electrode, a negative electrode and a separator disposed between the positive electrode and the negative electrode is wound in a roll. You may have. Also, for example, the electrode assembly may have a so-called stack and folding structure in which a positive electrode, a separator, and a negative electrode are laminated on a long film and then folded.
  • the outer package may be a flexible pouch (soft bag) or a hard case (hard casing).
  • the flexible pouch is usually formed of a laminate film, and sealing is achieved by heat sealing the periphery.
  • the laminate film is generally a film in which a metal foil and a polymer film are laminated, and specifically, a film having a three-layer structure consisting of an outer layer polymer film / metal foil / inner layer polymer film is exemplified.
  • the outer layer polymer film is for preventing permeation of moisture and the like and damage to the metal foil due to contact and the like, and polymers such as polyamide and polyester can be suitably used.
  • the metal foil is for preventing permeation of moisture and gas, and foils of copper, aluminum, stainless steel, etc. can be suitably used.
  • the inner layer polymer film is intended to protect the metal foil from the electrolyte contained inside and to melt and seal it at the time of heat sealing, and polyolefin or acid-modified polyolefin can be suitably used.
  • the thickness of the laminate film is not particularly limited, and for example, 1 ⁇ m or more and 1 mm or less is preferable.
  • the hard case is usually formed of a metal plate, and sealing is achieved by laser irradiation of the peripheral portion.
  • a metal plate a metal material made of aluminum, nickel, iron, copper, stainless steel or the like is generally used.
  • the thickness of the metal plate is not particularly limited, and for example, 1 ⁇ m or more and 1 mm or less is preferable.
  • Secondary batteries usually have two external terminals.
  • the two external terminals are connected to the electrode (positive electrode or negative electrode) through the current collection lead, and as a result are led out from the outer package.
  • the positive electrode active material has an average particle diameter D50 of 17 ⁇ m, a specific surface area of 0.2 m 2 / g, and is doped with 1 part by weight of Mg and 0.05 parts by weight of Zr with respect to 100 parts by weight of Co Lithium cobaltate (LCO) was used.
  • LCO Co Lithium cobaltate
  • a positive electrode active material 97.5 parts by weight of a positive electrode active material, 1 part by weight of carbon nanotubes having an average diameter of 10 nm as a conductive additive, and 1.5 parts by weight of polyvinylidene fluoride (PVdF) as a binder are dispersed in N-methylpyrrolidone (NMP)
  • NMP N-methylpyrrolidone
  • Example 3 A positive electrode plate was obtained by the same method as in Example 1 except that the pressure by the roll press was changed.
  • Example 11 A positive electrode plate was produced in the same manner as in Example 1 except that the following lithium cobaltate was used as the positive electrode active material.
  • Lithium cobaltate average particle diameter D50 10 ⁇ m; specific surface area 0.6 m 2 / g; doping amount with respect to 100 parts by weight of Co 5 parts by weight of Mg, 5 parts by weight of Zr.
  • a positive electrode plate was produced in the same manner as in Example 1 except that 2 parts by weight of carbon nanotubes having an average diameter of 10 nm was used as a conductive additive and 2 parts by weight of PVdF as a binder.
  • Example 2 A positive electrode plate was produced in the same manner as in Example 1 except that pressing with a roll press was not performed.
  • ⁇ Negative electrode> Artificial graphite (average particle diameter D50: 14 ⁇ m, specific surface area 2.0 m 2 / g) as a negative electrode active material, styrene butadiene rubber (SBR) as a binder and carboxymethyl cellulose (CMC) as a thickener in a weight ratio of 96: 2:
  • SBR styrene butadiene rubber
  • CMC carboxymethyl cellulose
  • a plurality of positive electrode plates and negative electrode plates were alternately stacked via a separator, and the positive and negative electrodes were bundled and tab-welded, respectively, and then placed in an aluminum laminated cup. After injecting the electrolyte there, a temporary vacuum seal was performed, and charge / discharge was performed at a current value equivalent to 0.2C. Thereafter, degassing treatment and vacuum main sealing were performed to prepare a cell with a capacity of 2 Ah. The cell was charged to 70% SOC and aged at 55 ° C. for 24 hours to complete the cell.
  • 1 M LiPF 6 is used as the electrolyte salt, 18 parts by volume of EC (ethylene carbonate), 32 parts by volume of DEC (diethyl carbonate), 18 parts by volume of PC (propylene carbonate), VC 1 part by volume of vinylene carbonate), 1 part by volume of FEC (fluoroethylene carbonate), 15 parts by volume of PP (propyl propionate), 10 parts by volume of ethyl propionate, 3 parts by volume of PS (propane sultone) and 2 parts by volume of ADN (adiponitrile)
  • EC ethylene carbonate
  • DEC diethyl carbonate
  • PC propylene carbonate
  • VC propylene carbonate
  • FEC fluoroethylene carbonate
  • 15 parts by volume of PP propyl propionate
  • 10 parts by volume of ethyl propionate 3 parts by volume of PS (propane sultone) and 2 parts by volume of ADN (adiponitrile)
  • the rate characteristics were calculated as a 1.5 C discharge capacity retention ratio represented by 1.5 C capacity / 0.2 C capacity ⁇ 100 (%). The larger the ratio, the better the rate characteristics. ⁇ 85: 85% or more (best): ⁇ : 80% or more (excellent): ⁇ : 70% or more (good): :: 60% or more (no problem in practical use (within tolerance)): X: less than 60% (there is a problem in practical use).
  • ⁇ Measurement method> (Pore curve factor) The pore curvature was measured as a pore bending degree ⁇ by a measuring device “Autopore IV 9500” (manufactured by Shimadzu Corporation) based on a mercury porosimeter. The physical property values of mercury used at the time of measurement were a contact angle of 130 °, a surface tension of 485.0 dyn / cm, and a density of 13.5335 g / mL.
  • the doping element and the doping amount of the positive electrode active material were measured by quantitative analysis by ICP analysis. When the amount of Co contained in the positive electrode active material was 100 parts by weight, the content of the doping element was determined.
  • Average particle size D50 The average particle diameter D50 was measured by a laser diffraction type particle size distribution measuring apparatus (LA960 manufactured by Horiba, Ltd.). In the present specification, the volume-based cumulative 50% diameter (D50) measured by this measuring device is expressed as an average particle diameter.
  • SSA Specific surface area
  • the electrode density is the density of the positive electrode active material layer of the positive electrode. Specifically, the thickness of the positive electrode active material layer is calculated by subtracting the thickness of the positive electrode current collector from the thickness of the positive electrode, and the product of the thickness of the positive electrode active material layer and the formation area of the positive electrode active material layer The volume is calculated, and the density is calculated by dividing the weight of the positive electrode active material layer by the volume.
  • the secondary battery of the present invention can be used in various fields where storage of electricity is assumed.
  • the secondary battery of the present invention is, by way of example only, in the field of electricity, information and communication in which mobile devices and the like are used (for example, mobile phones, smart phones, smart watches, notebook computers, digital cameras, activity meters, arms Mobile devices such as computers and electronic papers), home / small industrial applications (eg, electric tools, golf carts, home / care / industrial robots), large industrial applications (eg, forklifts, elevators, harbors) Field of crane), field of traffic system (for example, field of hybrid car, electric car, bus, train, electric assist bicycle, electric motorcycle etc.), electric power system application (for example, various power generation, road conditioner, smart grid, general household installation) Storage systems, etc.), IoT fields, and Sea applications (for example, spacecraft, fields such as submersible research vessel) can be used, such as in.
  • mobile devices and the like for example, mobile phones, smart phones, smart watches, notebook computers, digital cameras, activity meters, arms

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Abstract

La présente invention concerne un accumulateur au lithium-ion qui présente de meilleures caractéristiques de débit même lorsque la tension limite supérieure de charge atteint une tension supérieure ou égale à 4,41 V. L'accumulateur au lithium-ion comprend : une électrode positive ; une électrode négative ; un séparateur placé entre les électrodes positive et négative ; et un électrolyte non aqueux, la tension limite supérieure de charge étant supérieure ou égale à 4,41 V, l'électrode positive comportant une couche de matériau actif d'électrode positive dont le taux de tortuosité des pores mesuré à l'aide d'un porosimètre au mercure est compris entre 7 et 60, inclus.
PCT/JP2018/021665 2017-06-29 2018-06-06 Accumulateur au lithium-ion Ceased WO2019003835A1 (fr)

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WO2023054096A1 (fr) 2021-09-30 2023-04-06 パナソニックＩｐマネジメント株式会社 Électrode pour batterie secondaire, et batterie secondaire
WO2023054098A1 (fr) 2021-09-30 2023-04-06 パナソニックＩｐマネジメント株式会社 Électrode négative pour batterie secondaire, et batterie secondaire
WO2023054146A1 (fr) 2021-09-30 2023-04-06 パナソニックＩｐマネジメント株式会社 Batterie secondaire
JP2023099379A (ja) * 2022-01-01 2023-07-13 Ｃｏｎｎｅｘｘ Ｓｙｓｔｅｍｓ株式会社 リチウムイオン二次電池の正極、その製造方法、およびその正極を有するリチウムイオン二次電池
WO2023145428A1 (fr) 2022-01-28 2023-08-03 パナソニックＩｐマネジメント株式会社 Électrode négative pour batterie secondaire et batterie secondaire

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CN115832166B (zh) * 2021-09-23 2024-01-12 宁德时代新能源科技股份有限公司 正极极片、二次电池、电池模块、电池包和用电装置
JP7289414B1 (ja) 2023-02-14 2023-06-09 古河電池株式会社 非水電解質二次電池
JP7289413B1 (ja) 2023-02-14 2023-06-09 古河電池株式会社 非水電解質二次電池
JP7289415B1 (ja) 2023-02-15 2023-06-09 古河電池株式会社 非水電解質二次電池

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Publication number Priority date Publication date Assignee Title
WO2023054096A1 (fr) 2021-09-30 2023-04-06 パナソニックＩｐマネジメント株式会社 Électrode pour batterie secondaire, et batterie secondaire
WO2023054098A1 (fr) 2021-09-30 2023-04-06 パナソニックＩｐマネジメント株式会社 Électrode négative pour batterie secondaire, et batterie secondaire
WO2023054146A1 (fr) 2021-09-30 2023-04-06 パナソニックＩｐマネジメント株式会社 Batterie secondaire
JP2023099379A (ja) * 2022-01-01 2023-07-13 Ｃｏｎｎｅｘｘ Ｓｙｓｔｅｍｓ株式会社 リチウムイオン二次電池の正極、その製造方法、およびその正極を有するリチウムイオン二次電池
JP7370022B2 (ja) 2022-01-01 2023-10-27 Ｃｏｎｎｅｘｘ Ｓｙｓｔｅｍｓ株式会社 リチウムイオン二次電池の正極、その製造方法、およびその正極を有するリチウムイオン二次電池
WO2023145428A1 (fr) 2022-01-28 2023-08-03 パナソニックＩｐマネジメント株式会社 Électrode négative pour batterie secondaire et batterie secondaire

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