WO2018190048A1 - Positive electrode active material - Google Patents

Positive electrode active material Download PDF

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Publication number
WO2018190048A1
WO2018190048A1 PCT/JP2018/009219 JP2018009219W WO2018190048A1 WO 2018190048 A1 WO2018190048 A1 WO 2018190048A1 JP 2018009219 W JP2018009219 W JP 2018009219W WO 2018190048 A1 WO2018190048 A1 WO 2018190048A1
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Prior art keywords
positive electrode
active material
electrode active
satisfies
ion secondary
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PCT/JP2018/009219
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French (fr)
Japanese (ja)
Inventor
祐太 川本
武文 福本
博行 井関
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株式会社豊田自動織機
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Publication of WO2018190048A1 publication Critical patent/WO2018190048A1/en

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G45/00—Compounds of manganese
    • 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
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • 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
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • 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
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/10—Process efficiency
    • Y02P20/133—Renewable energy sources, e.g. sunlight

Definitions

  • the present invention relates to a positive electrode active material for a lithium ion secondary battery.
  • a lithium ion secondary battery includes a positive electrode, a negative electrode, and an electrolytic solution as main components.
  • the positive electrode includes a current collector and a positive electrode active material layer formed on the surface of the current collector and containing a positive electrode active material.
  • Patent Document 1 reports that a new composite oxide containing lithium, niobium, and iron or manganese can be used as a positive electrode active material of a lithium ion secondary battery.
  • the present invention has been made in view of such circumstances, and an object thereof is to provide a new positive electrode active material for providing a lithium ion secondary battery having an excellent capacity retention rate.
  • the present inventor conducted research on the composite oxide described in Patent Document 1 and found that there was room for improvement in terms of capacity retention rate. As a result of intensive studies by the present inventors, it has been found that the performance of the composite oxide as a positive electrode active material is improved by doping a certain element. The present invention has been completed based on such knowledge of the present inventors.
  • the positive electrode active material of the present invention is represented by the following composition formula (1), Li 1 + x Nb y Fe a Mn b A c O 2-d F d
  • A is selected from Be, Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Al, x satisfies 0 ⁇ x ⁇ 1, y satisfies 0 ⁇ y ⁇ 0.5, a and b satisfy 0.25 ⁇ a + b ⁇ 1, 0 ⁇ a ⁇ 1, 0 ⁇ b ⁇ 1, c satisfies 0 ⁇ c ⁇ 0.2; d satisfies 0 ⁇ d ⁇ 0.2, However, c and d are not 0 at the same time.
  • Example 2 is an X-ray diffraction chart of positive electrode active materials of Example 1-2, Example 2-2, and Comparative Example 1.
  • the numerical range “a to b” described in this specification includes the lower limit “a” and the upper limit “b”.
  • the numerical range can be configured by arbitrarily combining these upper limit value and lower limit value and the numerical values listed in the examples. Furthermore, numerical values arbitrarily selected from these numerical ranges can be used as new upper and lower numerical values.
  • the positive electrode active material of the present invention is represented by the following composition formula (1), Li 1 + x Nb y Fe a Mn b A c O 2-d F d
  • A is selected from Be, Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Al, x satisfies 0 ⁇ x ⁇ 1, y satisfies 0 ⁇ y ⁇ 0.5, a and b satisfy 0.25 ⁇ a + b ⁇ 1, 0 ⁇ a ⁇ 1, 0 ⁇ b ⁇ 1, c satisfies 0 ⁇ c ⁇ 0.2; d satisfies 0 ⁇ d ⁇ 0.2, However, c and d are not 0 at the same time.
  • the positive electrode active material of the present invention preferably exhibits a crystal structure that can be assigned to the space group Fm-3m.
  • the positive electrode active material of the present invention preferably exhibits a crystal structure that can be assigned to the NaCl type crystal structure.
  • the NaCl type crystal structure belongs to the space group Fm-3m. In “Fm ⁇ 3m”, “ ⁇ 3” represents 3 with an overline.
  • the positive electrode active material of the present invention can be expressed by being divided into a positive electrode active material represented by the following composition formula (1-1) and a positive electrode active material represented by the following composition formula (1-2).
  • A is selected from Be, Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, and Al.
  • x, y, a, b, and c are 0 ⁇ x ⁇ 1, 0 ⁇ y ⁇ 0.5, 0.25 ⁇ a + b ⁇ 1, 0 ⁇ a ⁇ 1, 0 ⁇ b ⁇ 1, 0 ⁇ c ⁇ 0. .2 is satisfied.
  • X is preferably in the range of 0 ⁇ x ⁇ 0.5, more preferably in the range of 0.05 ⁇ x ⁇ 0.4, and still more preferably in the range of 0.1 ⁇ x ⁇ 0.3.
  • y is preferably in the range of 0.05 ⁇ y ⁇ 0.5, more preferably in the range of 0.1 ⁇ y ⁇ 0.4, still more preferably in the range of 0.15 ⁇ y ⁇ 0.35.
  • the range of 2 ⁇ y ⁇ 0.35 is more preferable.
  • a and b it is preferable to satisfy the relationship of 0.25 ⁇ a + b ⁇ 0.75, more preferably to satisfy the relationship of 0.3 ⁇ a + b ⁇ 0.7, and 0.35 ⁇ a + b ⁇ 0. More preferably, the relationship of .5 is satisfied.
  • y a and b, it is preferable to satisfy the relationship 0.8 ⁇ 2y + a + b ⁇ 1.2, and it is more preferable to satisfy the relationship 0.9 ⁇ 2y + a + b ⁇ 1.1.
  • the positive electrode active material represented by the composition formula (1-1) includes A selected from Be, Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, and Al. A may be single or plural. A is considered to have an effect of stabilizing the structure of the positive electrode active material inside the positive electrode active material represented by the composition formula (1-1).
  • A is considered not to participate in or hardly participate in the oxidation-reduction reaction.
  • A is presumed to be present by substituting any one of Li, Nb, Fe and Mn.
  • A represents a space from which lithium ions are separated. It is thought to play a role as a “pillar” to hold. From the viewpoint of ease of substitution, it is preferable that A has a smaller atomic radius.
  • Be, Mg, Sc, Ti, Zr, and Al are preferable.
  • C indicating the composition ratio of A preferably satisfies 0.01 ⁇ c ⁇ 0.15, and more preferably satisfies 0.05 ⁇ c ⁇ 0.15. If c is too small, the stabilization effect of A may not be satisfactorily exhibited. On the other hand, if c is too large, the capacity of the positive electrode active material per unit mass may be small.
  • the positive electrode active material represented by the composition formula (1-2) will be described.
  • the positive electrode active material contains F.
  • F is presumed to be substituted for oxygen.
  • the composite oxide described in Patent Document 1 functions as a positive electrode active material by performing an oxidation-reduction reaction by releasing and occluding oxygen electrons contained in the composite oxide. Conceivable. However, it is considered that oxygen in a state where one electron is emitted is highly reactive because it is unstable, and can be easily separated from the positive electrode active material by being easily brought into O 2 when unstable oxygen approaches each other. .
  • F present in the positive electrode active material represented by the composition formula (1-2) physically controls the approach of unstable oxygens. Further, F has a high electron density due to its high electronegativity, and has an unshared electron pair. It is also estimated that HOMO, which is an orbit of such an unshared electron pair of F, and SOMO, which is an orbit of oxygen in a state where one electron is emitted, interact with each other, thereby stabilizing oxygen as a whole. . Furthermore, F is strongly ion-bonded with Nb, Fe, and Mn due to its high electronegativity, so it is considered that these metals suppress elution of these metals into the electrolyte. In any case, F is considered to have an effect of stabilizing the structure of the positive electrode active material inside the positive electrode active material represented by the composition formula (1-2).
  • D representing the composition ratio of F preferably satisfies 0.01 ⁇ d ⁇ 0.2, more preferably satisfies 0.03 ⁇ d ⁇ 0.15, and 0.06 ⁇ d ⁇ 0. It is more preferable to satisfy. If d is too small, the stabilization effect of F may not be satisfactorily exhibited. On the other hand, if d is too large, the capacity of the positive electrode active material per unit mass may be reduced.
  • a positive electrode active material represented by the following composition formula (1-3) can also be exemplified.
  • A is selected from Be, Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, and Al.
  • x, y, a, b, c and d are 0 ⁇ x ⁇ 1, 0 ⁇ y ⁇ 0.5, 0.25 ⁇ a + b ⁇ 1, 0 ⁇ a ⁇ 1, 0 ⁇ b ⁇ 1, 0 ⁇ c ⁇ 0.2 and 0 ⁇ d ⁇ 0.2 are satisfied.
  • the positive electrode active material represented by the composition formula (1-3) contains both A and F, it can be said that the positive electrode active material has both effects produced by A and F.
  • the explanations of the composition formula (1), the composition formula (1-1), and the composition formula (1-2) are used.
  • the manufacturing method of the positive electrode active material of this invention is demonstrated.
  • the positive electrode active material of the present invention may be synthesized by applying a solid phase method or a coprecipitation method that is employed when producing a general positive electrode active material.
  • the positive electrode active material of the present invention can be produced by mixing a lithium source, niobium source, iron source, manganese source, A source, and F source in a desired ratio and firing.
  • a hydroxide is precipitated from an aqueous solution in which niobium salt, iron salt, and manganese salt are mixed in a desired ratio to form a precipitate, and then the precipitate, lithium source, A source or
  • the positive electrode active material of this invention can be manufactured by mixing and baking with F source.
  • the firing temperature in the solid phase method and the coprecipitation method is preferably 500 to 1200 ° C, more preferably 700 to 1100 ° C, still more preferably 800 to 1000 ° C, and particularly preferably 900 to 1000 ° C. Firing is preferably performed in an inert gas atmosphere such as helium or argon.
  • lithium source examples include lithium oxide, lithium hydroxide, lithium carbonate, lithium hydrogen carbonate, and lithium fluoride.
  • examples of the niobium source or niobium salt include niobium oxide, niobium hydroxide, niobium sulfate, niobium nitrate, niobium chloride, niobium fluoride, and lithium niobate.
  • examples of the iron source or iron salt include iron oxide, iron hydroxide, iron sulfate, iron nitrate, iron chloride, and iron fluoride.
  • Examples of the manganese source or manganese salt include manganese oxide, manganese hydroxide, manganese sulfate, manganese nitrate, manganese chloride, and manganese fluoride.
  • Examples of the A source include oxidation A, hydroxide A, sulfuric acid A, nitric acid A, chloride A, and fluoride A.
  • Examples of the F source include hydrogen fluoride, lithium fluoride, niobium fluoride, iron fluoride, manganese fluoride, and fluoride A.
  • the synthesized cathode active material of the present invention is preferably subjected to a pulverization step for preparing a powder having an appropriate particle size distribution.
  • the average particle size of the positive electrode active material powder of the present invention is preferably 0.5 to 50 ⁇ m, more preferably 1 to 30 ⁇ m, and even more preferably 3 to 10 ⁇ m.
  • the average particle diameter means a 50% cumulative diameter (D 50 ) when a sample is measured with a general laser diffraction / scattering particle size distribution measuring apparatus.
  • the positive electrode for a lithium ion secondary battery comprising the positive electrode active material of the present invention is referred to as “the positive electrode of the present invention”
  • the lithium ion secondary battery comprising the positive electrode active material of the present invention is referred to as “the lithium ion secondary battery of the present invention”. It is called “second battery”.
  • the positive electrode of the present invention comprises a positive electrode active material layer containing the positive electrode active material of the present invention and a current collector.
  • the positive electrode active material layer is formed on the current collector. Examples of the proportion of the positive electrode active material of the present invention in the positive electrode active material layer include 30 to 100% by mass, 40 to 90% by mass, and 50 to 80% by mass.
  • the current collector refers to a chemically inert electronic conductor that keeps a current flowing through an electrode during discharge or charging of a lithium ion secondary battery.
  • the material of the current collector is not particularly limited as long as it is a metal that can withstand a voltage suitable for the active material to be used.
  • the current collector material is at least one selected from silver, copper, gold, aluminum, tungsten, cobalt, zinc, nickel, iron, platinum, tin, indium, titanium, ruthenium, tantalum, chromium, molybdenum, and stainless steel Examples of such a metal material can be given.
  • the current collector may be covered with a known protective layer. A current collector obtained by treating the surface of a current collector by a known method may be used as the current collector.
  • the potential of the positive electrode is 4 V or higher with respect to lithium, it is preferable to employ aluminum as the positive electrode current collector.
  • aluminum refers to pure aluminum, and aluminum having a purity of 99.0% or more is referred to as pure aluminum.
  • An alloy obtained by adding various elements to pure aluminum is referred to as an aluminum alloy. Examples of the aluminum alloy include Al—Cu, Al—Mn, Al—Fe, Al—Si, Al—Mg, Al—Mg—Si, and Al—Zn—Mg.
  • aluminum or aluminum alloy examples include A1000 series alloys (pure aluminum series) such as JIS A1085 and A1N30, A3000 series alloys (Al-Mn series) such as JIS A3003 and A3004, JIS A8079, A8021, etc. A8000-based alloy (Al-Fe-based).
  • the current collector can take the form of a foil, a sheet, a film, a linear shape, a rod shape, a mesh, or the like. Therefore, for example, a metal foil such as a copper foil, a nickel foil, an aluminum foil, and a stainless steel foil can be suitably used as the current collector.
  • a metal foil such as a copper foil, a nickel foil, an aluminum foil, and a stainless steel foil can be suitably used as the current collector.
  • the thickness is preferably in the range of 1 ⁇ m to 100 ⁇ m.
  • the positive electrode active material layer may contain a known positive electrode active material in addition to the positive electrode active material of the present invention. Further, the positive electrode active material layer preferably contains a binder and a conductive additive. As the binder and the conductive assistant contained in the positive electrode active material layer, those described in the later-described negative electrode may be appropriately employed.
  • the lithium ion secondary battery of the present invention specifically includes the positive electrode, the negative electrode, the electrolytic solution, and the separator of the present invention.
  • the negative electrode includes a current collector and a negative electrode active material layer formed on the current collector.
  • the negative electrode active material layer includes a known negative electrode active material.
  • the current collector for the negative electrode may be appropriately selected from those described for the positive electrode of the present invention.
  • the positive electrode active material and the negative electrode active material may be collectively referred to as “active material”, and the positive electrode active material layer and the negative electrode active material layer may be collectively referred to as “active material layer”. .
  • binder examples include fluorine-containing resins such as polyvinylidene fluoride, polytetrafluoroethylene, and fluororubber, thermoplastic resins such as polypropylene and polyethylene, imide resins such as polyimide and polyamideimide, alkoxysilyl group-containing resins, and carboxymethylcellulose. What is necessary is just to employ
  • Conductive aid is added to increase the conductivity of the electrode. Therefore, the conductive auxiliary agent may be added arbitrarily when the electrode conductivity is insufficient, and may not be added when the electrode conductivity is sufficiently excellent.
  • the conductive auxiliary agent may be any chemically inert electronic high conductor, such as carbon black, graphite, vapor grown carbon fiber (Vapor Grown Carbon Fiber), and various metal particles.
  • carbon black include acetylene black, ketjen black (registered trademark), furnace black, and channel black.
  • These conductive assistants can be added to the active material layer alone or in combination of two or more.
  • a current collecting method such as a roll coating method, a die coating method, a dip coating method, a doctor blade method, a spray coating method, or a curtain coating method can be used.
  • An active material may be applied to the surface of the body. Specifically, an active material, a binder, a solvent, and a conductive additive as necessary are mixed to form a slurry, and the slurry is applied to the surface of the current collector and then dried.
  • the solvent include N-methyl-2-pyrrolidone, methanol, methyl isobutyl ketone, and water.
  • the dried product may be compressed.
  • an active material layer may be formed on the surface of the current collector by preparing a mixture containing an active material, a binder, and if necessary, a conductive additive, and then bonding the mixture to the current collector. Good.
  • the separator separates the positive electrode and the negative electrode and allows lithium ions to pass while preventing a short circuit due to contact between the two electrodes.
  • a known separator may be employed, such as polytetrafluoroethylene, polypropylene, polyethylene, polyimide, polyamide, polyaramid (Aromatic polymer), polyester, polyacrylonitrile, and other synthetic resins, cellulose, amylose, and other polysaccharides, fibroin. , Porous materials, nonwoven fabrics, woven fabrics, and the like using one or more natural polymers such as keratin, lignin and suberin, and ceramics and other electrically insulating materials.
  • the separator may have a multilayer structure.
  • the electrolytic solution contains a non-aqueous solvent and an electrolyte dissolved in the non-aqueous solvent.
  • cyclic carbonates examples include ethylene carbonate, propylene carbonate, butylene carbonate, and vinylene carbonate
  • examples of the cyclic ester include gamma butyrolactone, 2-methyl-gamma butyrolactone, acetyl-gamma butyrolactone, and gamma valerolactone
  • Examples of the chain carbonate include dimethyl carbonate, diethyl carbonate, dibutyl carbonate, dipropyl carbonate, and ethyl methyl carbonate.
  • chain ester examples include propionic acid alkyl ester, malonic acid dialkyl ester, and acetic acid alkyl ester.
  • ethers examples include tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane, 1,2-diethoxyethane, and 1,2-dibutoxyethane.
  • non-aqueous solvent a compound in which part or all of hydrogen in the chemical structure of the specific solvent is substituted with fluorine may be employed.
  • Examples of the electrolyte include lithium salts such as LiClO 4 , LiAsF 6 , LiPF 6 , LiBF 4 , LiCF 3 SO 3 , and LiN (CF 3 SO 2 ) 2 .
  • a lithium salt such as LiClO 4 , LiPF 6 , LiBF 4 , LiCF 3 SO 3
  • a non-aqueous solvent such as fluoroethylene carbonate, ethylene carbonate, dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate.
  • a separator is sandwiched between a positive electrode and a negative electrode to form an electrode body.
  • the electrode body may be any of a stacked type in which a positive electrode, a separator and a negative electrode are stacked, or a wound type in which a positive electrode, a separator and a negative electrode are stacked.
  • the shape of the lithium ion secondary battery of the present invention is not particularly limited, and various shapes such as a cylindrical shape, a square shape, a coin shape, and a laminate shape can be adopted.
  • the lithium ion secondary battery of the present invention may be mounted on a vehicle.
  • the vehicle may be a vehicle that uses electric energy generated by a lithium ion secondary battery for all or a part of its power source.
  • the vehicle may be an electric vehicle or a hybrid vehicle.
  • a lithium ion secondary battery is mounted on a vehicle, a plurality of lithium ion secondary batteries may be connected in series to form an assembled battery.
  • devices equipped with lithium ion secondary batteries include various home appliances driven by batteries such as personal computers and portable communication devices, office devices, and industrial devices in addition to vehicles.
  • the lithium ion secondary battery of the present invention includes wind power generation, solar power generation, hydroelectric power generation and other power system power storage devices and power smoothing devices, power supplies for ships and / or auxiliary power supply sources, aircraft, Power supply for spacecraft and / or auxiliary equipment, auxiliary power supply for vehicles that do not use electricity as a power source, power supply for mobile home robots, power supply for system backup, power supply for uninterruptible power supply, You may use for the electrical storage apparatus which stores temporarily the electric power required for charge in the charging station for electric vehicles.
  • Example 1-1 Li 2 CO 3, Nb 2 O 5, Mn 2 O 3 and Mg (NO 3) the 2 ⁇ 6H 2 O, Li: Nb: Mn: Mg is 1.225: 0.275: 0.4: 0.1 These powders were weighed at a ratio to give, and these powders were put into a ball mill. After adding 1 mass% propylene glycol with respect to the whole powder, it mixed by the ball mill, and was set as the mixture. After the mixture was molded, it was heated at 950 ° C. for 12 hours under an argon gas atmosphere to produce a fired product. The fired product was crushed to obtain a positive electrode active material of Example 1-1.
  • the theoretical composition of the positive electrode active material of Example 1-1 is Li 1.225 Nb 0.275 Mn 0.4 Mg 0.1 O 2 .
  • Example 1-1 5 parts by weight of the positive electrode active material of Example 1-1, 3 parts by weight of acetylene black as a conductive assistant, 2 parts by weight of polytetrafluoroethylene as a binder, and an appropriate amount of N-methyl-2-pyrrolidone Mix to make a slurry.
  • An aluminum foil was prepared as a current collector, and a slurry was applied to the aluminum foil and dried to obtain a positive electrode of Example 1-1.
  • Lithium foil was prepared and used as a negative electrode.
  • a polyethylene porous membrane having a thickness of 20 ⁇ m was prepared as a separator.
  • LiPF 6 was dissolved in a solvent obtained by mixing 5 parts by volume of ethylene carbonate and diethyl carbonate 5 parts by volume in a concentration of 1 mol / L electrolyte solution.
  • the separator was sandwiched between the positive electrode and the negative electrode of Example 1-1 to obtain an electrode body.
  • This electrode body was accommodated in a coin-type battery case CR2032 (Hosen Co., Ltd.), and an electrolyte was further injected to obtain a sealed coin-type battery. This was designated as the lithium ion secondary battery of Example 1-1.
  • Example 1-2 Li 2 CO 3 , Nb 2 O 5 , Mn 2 O 3 and Mg (NO 3 ) 2 .6H 2 O, Li: Nb: Mn: Mg 1.2: 0.3: 0.35: 0.1
  • a positive electrode active material, a positive electrode, and a lithium ion secondary battery of Example 1-2 were produced in the same manner as in Example 1-1, except that they were weighed at a ratio of The theoretical composition of the positive electrode active material of Example 1-2 is Li 1.2 Nb 0.3 Mn 0.35 Mg 0.1 O 2 .
  • Example 1-3 Li 2 CO 3 , Nb 2 O 5 , Mn 2 O 3 and Mg (NO 3 ) 2 .6H 2 O, Li: Nb: Mn: Mg 1.1: 0.3: 0.4: 0.1
  • a positive electrode active material, a positive electrode, and a lithium ion secondary battery of Example 1-3 were produced in the same manner as in Example 1-1, except that they were weighed at a ratio of The theoretical composition of the positive electrode active material of Example 1-3 is Li 1.1 Nb 0.3 Mn 0.4 Mg 0.1 O 2 .
  • Example 2-1 Li 2 CO 3 , Nb 2 O 5 , Mn 2 O 3 and LiF were weighed at a ratio of Li: Nb: Mn: F of 1.25: 0.3: 0.4: 0.05, and these The powder was put into a ball mill. After adding 1 mass% propylene glycol with respect to the whole powder, it mixed by the ball mill, and was set as the mixture. After the mixture was molded, it was heated at 950 ° C. for 12 hours under an argon gas atmosphere to produce a fired product. The fired product was crushed to obtain a positive electrode active material of Example 2-1. Thereafter, the positive electrode and the lithium ion secondary battery of Example 2-1 were produced in the same manner as in Example 1-1.
  • the composition of the theoretical positive electrode active material in Example 2-1 is a Li 1.25 Nb 0.3 Mn 0.4 O 1.95 F 0.05.
  • Example 2-2 Li 2 CO 3 , Nb 2 O 5 , Mn 2 O 3 and LiF were weighed and used at a ratio such that Li: Nb: Mn: F was 1.2: 0.3: 0.4: 0.1.
  • a positive electrode active material, a positive electrode, and a lithium ion secondary battery of Example 2-2 were produced in the same manner as in Example 2-1, except for the above.
  • the theoretical composition of the positive electrode active material of Example 2-2 is Li 1.2 Nb 0.3 Mn 0.4 O 1.9 F 0.1 .
  • Example 1 The positive electrode active materials of Example 1-1 and Example 2-1 were analyzed by SEM-EDX in which a scanning electron microscope (SEM) and an energy dispersive X-ray analyzer (EDX) were combined. The presence of Mg was confirmed from the positive electrode active material of Example 1-1, and the presence of F was confirmed from the positive electrode active material of Example 2-1.
  • SEM scanning electron microscope
  • EDX energy dispersive X-ray analyzer
  • Example 2 The positive electrode active materials of Example 1-2, Example 2-2, and Comparative Example 1 were analyzed with a powder X-ray diffractometer using Cu—K ⁇ rays. An X-ray diffraction chart is shown in FIG. All of the positive electrode active materials showed diffraction patterns that could be assigned to the NaCl type crystal structure.

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  • Inorganic Chemistry (AREA)
  • Organic Chemistry (AREA)
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Abstract

A positive electrode active material characterized by being represented by compositional formula (1) noted hereafter, Li1+xNbyFeaMnbAcO2–dFd (1), where: A is selected from Be, Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, and Al; x satisfies 0 < x < 1; y satisfies 0 < y < 0.5; a and b satisfy 0.25 ≤ a + b < 1, 0 ≤ a < 1, and 0 ≤ b < 1; c satisfies 0 ≤ c ≤ 0.2; and d satisfies 0 ≤ d ≤ 0.2, but c and d are not 0 simultaneously.

Description

正極活物質Cathode active material
　本発明は、リチウムイオン二次電池の正極活物質に関するものである。 The present invention relates to a positive electrode active material for a lithium ion secondary battery.
　リチウムイオン二次電池は小型で大容量であるため、携帯電話やノート型パソコンなどの種々の機器の電池として用いられている。リチウムイオン二次電池は、主な構成要素として、正極、負極及び電解液を備える。正極は、集電体と、該集電体の表面に形成され、正極活物質を含有する正極活物質層とを有する。 Since lithium ion secondary batteries are small and have a large capacity, they are used as batteries for various devices such as mobile phones and notebook computers. A lithium ion secondary battery includes a positive electrode, a negative electrode, and an electrolytic solution as main components. The positive electrode includes a current collector and a positive electrode active material layer formed on the surface of the current collector and containing a positive electrode active material.
　リチウムイオン二次電池の正極活物質としては、種々の材料が用いられることが知られており、また、優れた正極活物質となり得る材料が探求されている。例えば、特許文献１にて、リチウム、ニオブ、及び、鉄若しくはマンガンを含有する新たな複合酸化物が、リチウムイオン二次電池の正極活物質として使用可能なことが報告されている。 It is known that various materials are used as a positive electrode active material of a lithium ion secondary battery, and a material that can be an excellent positive electrode active material is being sought. For example, Patent Document 1 reports that a new composite oxide containing lithium, niobium, and iron or manganese can be used as a positive electrode active material of a lithium ion secondary battery.
国際公開第２０１４／１５６１５３号International Publication No. 2014/156153
　近年、産業界からは、容量維持率に優れるリチウムイオン二次電池が求められており、それを実現するための、新たな正極活物質が求められている。 In recent years, a lithium ion secondary battery having an excellent capacity retention rate has been demanded by the industry, and a new positive electrode active material for realizing this has been demanded.
　本発明は、かかる事情に鑑みて為されたものであり、容量維持率に優れるリチウムイオン二次電池を提供するための新たな正極活物質を提供することを目的とする。 The present invention has been made in view of such circumstances, and an object thereof is to provide a new positive electrode active material for providing a lithium ion secondary battery having an excellent capacity retention rate.
　本発明者は、特許文献１に記載の複合酸化物についての研究を行ったところ、容量維持率の観点で、改良の余地があることに気が付いた。そして、本発明者の鋭意検討の結果、ある種の元素をドープすることで、当該複合酸化物の正極活物質としての性能が向上することを見出した。本発明は、本発明者のかかる知見に基づき、完成されたものである。 The present inventor conducted research on the composite oxide described in Patent Document 1 and found that there was room for improvement in terms of capacity retention rate. As a result of intensive studies by the present inventors, it has been found that the performance of the composite oxide as a positive electrode active material is improved by doping a certain element. The present invention has been completed based on such knowledge of the present inventors.
　本発明の正極活物質は、下記組成式（１）で表され、
　Ｌｉ１＋ｘＮｂｙＦｅａＭｎｂＡｃＯ２―ｄＦｄ　　　（１）
　ＡはＢｅ、Ｍｇ、Ｃａ、Ｓｒ、Ｂａ、Ｒａ、Ｓｃ、Ｙ、Ｔｉ、Ｚｒ、Ａｌから選択され、
　ｘは、０＜ｘ＜１を満足し、
　ｙは、０＜ｙ＜０．５を満足し、
　ａ及びｂは、０．２５≦ａ＋ｂ＜１、０≦ａ＜１、０≦ｂ＜１を満足し、
　ｃは、０≦ｃ≦０．２を満足し、
　ｄは、０≦ｄ≦０．２を満足し、
　ただし、ｃ及びｄは同時に０ではないことを特徴とする。 The positive electrode active material of the present invention is represented by the following composition formula (1),
Li 1 + x Nb y Fe a Mn b A c O 2-d F d (1)
A is selected from Be, Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Al,
x satisfies 0 <x <1,
y satisfies 0 <y <0.5,
a and b satisfy 0.25 ≦ a + b <1, 0 ≦ a <1, 0 ≦ b <1,
c satisfies 0 ≦ c ≦ 0.2;
d satisfies 0 ≦ d ≦ 0.2,
However, c and d are not 0 at the same time.
　本発明の正極活物質に因り、容量維持率に優れるリチウムイオン二次電池を提供できる。 Due to the positive electrode active material of the present invention, it is possible to provide a lithium ion secondary battery having an excellent capacity retention rate.
実施例１－２、実施例２－２及び比較例１の正極活物質のＸ線回折チャートである。2 is an X-ray diffraction chart of positive electrode active materials of Example 1-2, Example 2-2, and Comparative Example 1.
　以下に、本発明を実施するための形態を説明する。なお、特に断らない限り、本明細書に記載された数値範囲「ａ～ｂ」は、下限ａ及び上限ｂをその範囲に含む。そして、これらの上限値及び下限値、ならびに実施例中に列記した数値も含めてそれらを任意に組み合わせることで数値範囲を構成し得る。さらに、これらの数値範囲内から任意に選択した数値を、新たな上限や下限の数値とすることができる。 Hereinafter, modes for carrying out the present invention will be described. Unless otherwise specified, the numerical range “a to b” described in this specification includes the lower limit “a” and the upper limit “b”. The numerical range can be configured by arbitrarily combining these upper limit value and lower limit value and the numerical values listed in the examples. Furthermore, numerical values arbitrarily selected from these numerical ranges can be used as new upper and lower numerical values.
　本発明の正極活物質は、下記組成式（１）で表され、
　Ｌｉ１＋ｘＮｂｙＦｅａＭｎｂＡｃＯ２―ｄＦｄ　　　（１）
　ＡはＢｅ、Ｍｇ、Ｃａ、Ｓｒ、Ｂａ、Ｒａ、Ｓｃ、Ｙ、Ｔｉ、Ｚｒ、Ａｌから選択され、
　ｘは、０＜ｘ＜１を満足し、
　ｙは、０＜ｙ＜０．５を満足し、
　ａ及びｂは、０．２５≦ａ＋ｂ＜１、０≦ａ＜１、０≦ｂ＜１を満足し、
　ｃは、０≦ｃ≦０．２を満足し、
　ｄは、０≦ｄ≦０．２を満足し、
　ただし、ｃ及びｄは同時に０ではないことを特徴とする。 The positive electrode active material of the present invention is represented by the following composition formula (1),
Li 1 + x Nb y Fe a Mn b A c O 2-d F d (1)
A is selected from Be, Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Al,
x satisfies 0 <x <1,
y satisfies 0 <y <0.5,
a and b satisfy 0.25 ≦ a + b <1, 0 ≦ a <1, 0 ≦ b <1,
c satisfies 0 ≦ c ≦ 0.2;
d satisfies 0 ≦ d ≦ 0.2,
However, c and d are not 0 at the same time.
　本発明の正極活物質は、空間群Ｆｍ－３ｍに帰属可能な結晶構造を示すものが好ましい。また、本発明の正極活物質は、ＮａＣｌ型結晶構造に帰属可能な結晶構造を示すものが好ましい。ＮａＣｌ型結晶構造は、空間群Ｆｍ－３ｍに帰属される。なお、「Ｆｍ－３ｍ」において、「－３」は上線を付した３を表したものである。 The positive electrode active material of the present invention preferably exhibits a crystal structure that can be assigned to the space group Fm-3m. In addition, the positive electrode active material of the present invention preferably exhibits a crystal structure that can be assigned to the NaCl type crystal structure. The NaCl type crystal structure belongs to the space group Fm-3m. In “Fm−3m”, “−3” represents 3 with an overline.
　本発明の正極活物質は、下記組成式（１－１）で表される正極活物質と、下記組成式（１－２）で表される正極活物質に分けて表現することができる。
　Ｌｉ１＋ｘＮｂｙＦｅａＭｎｂＡｃＯ２　　　（１－１）
　組成式（１－１）において、ＡはＢｅ、Ｍｇ、Ｃａ、Ｓｒ、Ｂａ、Ｒａ、Ｓｃ、Ｙ、Ｔｉ、Ｚｒ、Ａｌから選択される。ｘ、ｙ、ａ、ｂ及びｃは、０＜ｘ＜１、０＜ｙ＜０．５、０．２５≦ａ＋ｂ＜１、０≦ａ＜１、０≦ｂ＜１、０＜ｃ≦０．２を満足する。
　Ｌｉ１＋ｘＮｂｙＦｅａＭｎｂＯ２―ｄＦｄ　　　（１－２）
　組成式（１－２）において、ｘ、ｙ、ａ、ｂ及びｄは、０＜ｘ＜１、０＜ｙ＜０．５、０．２５≦ａ＋ｂ＜１、０≦ａ＜１、０≦ｂ＜１、０＜ｄ≦０．２を満足する。 The positive electrode active material of the present invention can be expressed by being divided into a positive electrode active material represented by the following composition formula (1-1) and a positive electrode active material represented by the following composition formula (1-2).
Li 1 + x Nb y Fe a Mn b Ac O 2 (1-1)
In the composition formula (1-1), A is selected from Be, Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, and Al. x, y, a, b, and c are 0 <x <1, 0 <y <0.5, 0.25 ≦ a + b <1, 0 ≦ a <1, 0 ≦ b <1, 0 <c ≦ 0. .2 is satisfied.
Li 1 + x Nb y Fe a Mn b O 2-d F d (1-2)
In the composition formula (1-2), x, y, a, b and d are 0 <x <1, 0 <y <0.5, 0.25 ≦ a + b <1, 0 ≦ a <1, 0 ≦ b <1, 0 <d ≦ 0.2 is satisfied.
　まず、組成式（１－１）と組成式（１－２）に共通する、ｘ、ｙ、ａ、ｂについて説明する。かかる説明については、特許文献１の記載を一部引用する。 First, x, y, a, and b common to the composition formula (1-1) and the composition formula (1-2) will be described. For this explanation, a part of the description of Patent Document 1 is cited.
　ｘとしては、０＜ｘ＜０．５の範囲が好ましく、０．０５≦ｘ≦０．４の範囲がより好ましく、０．１≦ｘ≦０．３の範囲がさらに好ましい。ｙとしては、０．０５≦ｙ＜０．５の範囲が好ましく、０．１≦ｙ≦０．４の範囲がより好ましく、０．１５≦ｙ≦０．３５の範囲がさらに好ましく、０．２≦ｙ≦０．３５の範囲がさらに好ましい。 X is preferably in the range of 0 <x <0.5, more preferably in the range of 0.05 ≦ x ≦ 0.4, and still more preferably in the range of 0.1 ≦ x ≦ 0.3. y is preferably in the range of 0.05 ≦ y <0.5, more preferably in the range of 0.1 ≦ y ≦ 0.4, still more preferably in the range of 0.15 ≦ y ≦ 0.35. The range of 2 ≦ y ≦ 0.35 is more preferable.
　ａとｂについては、０．２５≦ａ＋ｂ≦０．７５の関係を満足するのが好ましく、０．３≦ａ＋ｂ≦０．７の関係を満足するのがより好ましく、０．３５≦ａ＋ｂ≦０．５の関係を満足するのがさらに好ましい。また、ｙとａとｂについては、０．８≦２ｙ＋ａ＋ｂ≦１．２の関係を満足するのが好ましく、０．９≦２ｙ＋ａ＋ｂ≦１．１の関係を満足するのがより好ましい。 For a and b, it is preferable to satisfy the relationship of 0.25 ≦ a + b ≦ 0.75, more preferably to satisfy the relationship of 0.3 ≦ a + b ≦ 0.7, and 0.35 ≦ a + b ≦ 0. More preferably, the relationship of .5 is satisfied. As for y, a and b, it is preferable to satisfy the relationship 0.8 ≦ 2y + a + b ≦ 1.2, and it is more preferable to satisfy the relationship 0.9 ≦ 2y + a + b ≦ 1.1.
　次に、組成式（１－１）で表される正極活物質について説明する。
　当該正極活物質には、Ｂｅ、Ｍｇ、Ｃａ、Ｓｒ、Ｂａ、Ｒａ、Ｓｃ、Ｙ、Ｔｉ、Ｚｒ、Ａｌから選択されるＡが含まれる。Ａは、単独でもよいし、複数でもよい。Ａは、組成式（１－１）で表される正極活物質内部で、正極活物質の構造を安定化する効果を奏すると考えられる。 Next, the positive electrode active material represented by the composition formula (1-1) will be described.
The positive electrode active material includes A selected from Be, Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, and Al. A may be single or plural. A is considered to have an effect of stabilizing the structure of the positive electrode active material inside the positive electrode active material represented by the composition formula (1-1).
　本発明の正極活物質を具備するリチウムイオン二次電池の通常の充放電電位において、Ａは酸化還元反応に関与しない又は関与し難いと考えられる。本発明の正極活物質において、ＡはＬｉ、Ｎｂ、Ｆｅ及びＭｎのいずれかと置換して存在すると推定され、そして、充電状態の本発明の正極活物質において、Ａはリチウムイオンの離脱した空間を保持する“柱”としての役割を担っていると考えられる。置換容易性の観点からは、Ａは、その原子半径が小さい方が好ましい。Ａとしては、Ｂｅ、Ｍｇ、Ｓｃ、Ｔｉ、Ｚｒ、Ａｌが好ましいといえる。 In the normal charge / discharge potential of the lithium ion secondary battery comprising the positive electrode active material of the present invention, A is considered not to participate in or hardly participate in the oxidation-reduction reaction. In the positive electrode active material of the present invention, A is presumed to be present by substituting any one of Li, Nb, Fe and Mn. In the positive electrode active material of the present invention in a charged state, A represents a space from which lithium ions are separated. It is thought to play a role as a “pillar” to hold. From the viewpoint of ease of substitution, it is preferable that A has a smaller atomic radius. As A, Be, Mg, Sc, Ti, Zr, and Al are preferable.
　Ａの組成比を示すｃとしては、０．０１≦ｃ≦０．１５を満足するのが好ましく、０．０５≦ｃ≦０．１５を満足するのがより好ましい。ｃが過小であれば、Ａの安定化効果が満足に発揮できない場合があり、他方、ｃが過大であれば、単位質量あたりの正極活物質の容量が小さくなる場合がある。 C indicating the composition ratio of A preferably satisfies 0.01 ≦ c ≦ 0.15, and more preferably satisfies 0.05 ≦ c ≦ 0.15. If c is too small, the stabilization effect of A may not be satisfactorily exhibited. On the other hand, if c is too large, the capacity of the positive electrode active material per unit mass may be small.
　次に、組成式（１－２）で表される正極活物質について説明する。
　当該正極活物質には、Ｆが含まれる。Ｆは、本発明の正極活物質において、酸素と置換して存在すると推定される。 Next, the positive electrode active material represented by the composition formula (1-2) will be described.
The positive electrode active material contains F. In the positive electrode active material of the present invention, F is presumed to be substituted for oxygen.
　ここで、特許文献１に記載された複合酸化物は、複合酸化物に含まれる酸素の電子が放出されること及び吸蔵されることで酸化還元反応を行い、正極活物質として機能していると考えられる。しかし、一電子が放出された状態の酸素は不安定であるため反応性が高く、そして、不安定な酸素同士が接近することで容易にＯ２となり、正極活物質から離脱し得ると考えられる。 Here, the composite oxide described in Patent Document 1 functions as a positive electrode active material by performing an oxidation-reduction reaction by releasing and occluding oxygen electrons contained in the composite oxide. Conceivable. However, it is considered that oxygen in a state where one electron is emitted is highly reactive because it is unstable, and can be easily separated from the positive electrode active material by being easily brought into O 2 when unstable oxygen approaches each other. .
　組成式（１－２）で表される正極活物質に存在するＦは、不安定な酸素同士の接近を物理的に制御すると推定される。また、Ｆは、その高い電気陰性度により、電子密度が高く、かつ、非共有電子対を有する。かかるＦの非共有電子対の軌道であるＨＯＭＯと、一電子が放出された状態の酸素の軌道であるＳＯＭＯとが、相互作用することで、全体として、酸素を安定化しているとも推定される。さらに、Ｆは、その高い電気陰性度により、Ｎｂ、Ｆｅ、Ｍｎと強くイオン結合するため、これらの金属の電解液への溶出を抑制しているとも考えられる。いずれにせよ、Ｆは、組成式（１－２）で表される正極活物質内部で、正極活物質の構造を安定化する効果を奏すると考えられる。 It is estimated that F present in the positive electrode active material represented by the composition formula (1-2) physically controls the approach of unstable oxygens. Further, F has a high electron density due to its high electronegativity, and has an unshared electron pair. It is also estimated that HOMO, which is an orbit of such an unshared electron pair of F, and SOMO, which is an orbit of oxygen in a state where one electron is emitted, interact with each other, thereby stabilizing oxygen as a whole. . Furthermore, F is strongly ion-bonded with Nb, Fe, and Mn due to its high electronegativity, so it is considered that these metals suppress elution of these metals into the electrolyte. In any case, F is considered to have an effect of stabilizing the structure of the positive electrode active material inside the positive electrode active material represented by the composition formula (1-2).
　Ｆの組成比を示すｄとしては、０．０１≦ｄ≦０．２を満足するのが好ましく、０．０３≦ｄ≦０．１５を満足するのがより好ましく、０．０６≦ｄ≦０．１２を満足するのがさらに好ましい。ｄが過小であれば、Ｆの安定化効果が満足に発揮できない場合があり、他方、ｄが過大であれば、単位質量あたりの正極活物質の容量が小さくなる場合がある。 D representing the composition ratio of F preferably satisfies 0.01 ≦ d ≦ 0.2, more preferably satisfies 0.03 ≦ d ≦ 0.15, and 0.06 ≦ d ≦ 0. It is more preferable to satisfy. If d is too small, the stabilization effect of F may not be satisfactorily exhibited. On the other hand, if d is too large, the capacity of the positive electrode active material per unit mass may be reduced.
　また、本発明の正極活物質として、下記組成式（１－３）で表される正極活物質も例示できる。
　Ｌｉ１＋ｘＮｂｙＦｅａＭｎｂＡｃＯ２―ｄＦｄ　　　（１－３）
　組成式（１－３）において、ＡはＢｅ、Ｍｇ、Ｃａ、Ｓｒ、Ｂａ、Ｒａ、Ｓｃ、Ｙ、Ｔｉ、Ｚｒ、Ａｌから選択される。ｘ、ｙ、ａ、ｂ、ｃ及びｄは、０＜ｘ＜１、０＜ｙ＜０．５、０．２５≦ａ＋ｂ＜１、０≦ａ＜１、０≦ｂ＜１、０＜ｃ≦０．２、０＜ｄ≦０．２を満足する。 Further, as the positive electrode active material of the present invention, a positive electrode active material represented by the following composition formula (1-3) can also be exemplified.
Li 1 + x Nb y Fe a Mn b A c O 2 -d F d (1-3)
In the composition formula (1-3), A is selected from Be, Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, and Al. x, y, a, b, c and d are 0 <x <1, 0 <y <0.5, 0.25 ≦ a + b <1, 0 ≦ a <1, 0 ≦ b <1, 0 <c ≦ 0.2 and 0 <d ≦ 0.2 are satisfied.
　組成式（１－３）で表される正極活物質は、ＡとＦの両者を含むため、ＡとＦに因って奏される両効果を有するといえる。組成式（１－３）の各要素の説明としては、組成式（１）、組成式（１－１）及び組成式（１－２）での説明を援用する。 Since the positive electrode active material represented by the composition formula (1-3) contains both A and F, it can be said that the positive electrode active material has both effects produced by A and F. As the description of each element of the composition formula (1-3), the explanations of the composition formula (1), the composition formula (1-1), and the composition formula (1-2) are used.
　本発明の正極活物質の製造方法について説明する。
　本発明の正極活物質を製造するには、一般的な正極活物質を製造する際に採用される、固相法や共沈法を応用して合成すればよい。固相法の場合には、リチウム源、ニオブ源、鉄源、マンガン源、Ａ源、Ｆ源を、所望の比率で混合し、焼成することで、本発明の正極活物質を製造できる。共沈法の場合には、ニオブ塩、鉄塩、マンガン塩を所望の比率で混合した水溶液から、水酸化物を沈殿させて沈殿物とし、次いで、沈殿物と、リチウム源と、Ａ源又はＦ源とを混合して焼成することで、本発明の正極活物質を製造できる。固相法及び共沈法の焼成温度としては、５００～１２００℃が好ましく、７００～１１００℃がより好ましく、８００～１０００℃がさらに好ましく、９００～１０００℃が特に好ましい。焼成は、ヘリウムやアルゴンなどの不活性ガス雰囲気下で行うのが好ましい。 The manufacturing method of the positive electrode active material of this invention is demonstrated.
In order to produce the positive electrode active material of the present invention, it may be synthesized by applying a solid phase method or a coprecipitation method that is employed when producing a general positive electrode active material. In the case of the solid phase method, the positive electrode active material of the present invention can be produced by mixing a lithium source, niobium source, iron source, manganese source, A source, and F source in a desired ratio and firing. In the case of the coprecipitation method, a hydroxide is precipitated from an aqueous solution in which niobium salt, iron salt, and manganese salt are mixed in a desired ratio to form a precipitate, and then the precipitate, lithium source, A source or The positive electrode active material of this invention can be manufactured by mixing and baking with F source. The firing temperature in the solid phase method and the coprecipitation method is preferably 500 to 1200 ° C, more preferably 700 to 1100 ° C, still more preferably 800 to 1000 ° C, and particularly preferably 900 to 1000 ° C. Firing is preferably performed in an inert gas atmosphere such as helium or argon.
　リチウム源としては、酸化リチウム、水酸化リチウム、炭酸リチウム、炭酸水素リチウム、フッ化リチウムを例示できる。ニオブ源又はニオブ塩としては、酸化ニオブ、水酸化ニオブ、硫酸ニオブ、硝酸ニオブ、塩化ニオブ、フッ化ニオブ、ニオブ酸リチウムを例示できる。鉄源又は鉄塩としては、酸化鉄、水酸化鉄、硫酸鉄、硝酸鉄、塩化鉄、フッ化鉄を例示できる。マンガン源又はマンガン塩としては、酸化マンガン、水酸化マンガン、硫酸マンガン、硝酸マンガン、塩化マンガン、フッ化マンガンを例示できる。Ａ源としては、酸化Ａ、水酸化Ａ、硫酸Ａ、硝酸Ａ、塩化Ａ、フッ化Ａを例示できる。Ｆ源としては、フッ化水素、フッ化リチウム、フッ化ニオブ、フッ化鉄、フッ化マンガン、フッ化Ａを例示できる。 Examples of the lithium source include lithium oxide, lithium hydroxide, lithium carbonate, lithium hydrogen carbonate, and lithium fluoride. Examples of the niobium source or niobium salt include niobium oxide, niobium hydroxide, niobium sulfate, niobium nitrate, niobium chloride, niobium fluoride, and lithium niobate. Examples of the iron source or iron salt include iron oxide, iron hydroxide, iron sulfate, iron nitrate, iron chloride, and iron fluoride. Examples of the manganese source or manganese salt include manganese oxide, manganese hydroxide, manganese sulfate, manganese nitrate, manganese chloride, and manganese fluoride. Examples of the A source include oxidation A, hydroxide A, sulfuric acid A, nitric acid A, chloride A, and fluoride A. Examples of the F source include hydrogen fluoride, lithium fluoride, niobium fluoride, iron fluoride, manganese fluoride, and fluoride A.
　合成後の本発明の正極活物質は、適切な粒度分布の粉末に調製する粉砕工程に供されるのが好ましい。本発明の正極活物質の粉末の平均粒子径としては、０．５～５０μｍが好ましく、１～３０μｍがより好ましく、３～１０μｍがさらに好ましい。なお、本明細書において、平均粒子径とは、一般的なレーザー回折散乱式粒度分布測定装置で試料を測定した際の５０％累積径（Ｄ５０）を意味する。 The synthesized cathode active material of the present invention is preferably subjected to a pulverization step for preparing a powder having an appropriate particle size distribution. The average particle size of the positive electrode active material powder of the present invention is preferably 0.5 to 50 μm, more preferably 1 to 30 μm, and even more preferably 3 to 10 μm. In this specification, the average particle diameter means a 50% cumulative diameter (D 50 ) when a sample is measured with a general laser diffraction / scattering particle size distribution measuring apparatus.
　以下、本発明の正極活物質を具備するリチウムイオン二次電池用正極を「本発明の正極」といい、本発明の正極活物質を具備するリチウムイオン二次電池を「本発明のリチウムイオン二次電池」という。 Hereinafter, the positive electrode for a lithium ion secondary battery comprising the positive electrode active material of the present invention is referred to as “the positive electrode of the present invention”, and the lithium ion secondary battery comprising the positive electrode active material of the present invention is referred to as “the lithium ion secondary battery of the present invention”. It is called “second battery”.
　本発明の正極は、本発明の正極活物質を含む正極活物質層、及び、集電体を具備する。正極活物質層は集電体上に形成される。正極活物質層における本発明の正極活物質の配合割合として、３０～１００質量％、４０～９０質量％、５０～８０質量％、を例示できる。 The positive electrode of the present invention comprises a positive electrode active material layer containing the positive electrode active material of the present invention and a current collector. The positive electrode active material layer is formed on the current collector. Examples of the proportion of the positive electrode active material of the present invention in the positive electrode active material layer include 30 to 100% by mass, 40 to 90% by mass, and 50 to 80% by mass.
　集電体は、リチウムイオン二次電池の放電又は充電の間、電極に電流を流し続けるための化学的に不活性な電子伝導体をいう。集電体の材料は、使用する活物質に適した電圧に耐え得る金属であれば特に制限はない。集電体の材料としては、銀、銅、金、アルミニウム、タングステン、コバルト、亜鉛、ニッケル、鉄、白金、錫、インジウム、チタン、ルテニウム、タンタル、クロム、モリブデンから選ばれる少なくとも一種、並びにステンレス鋼などの金属材料を例示することができる。集電体は公知の保護層で被覆されていても良い。ある集電体の表面を公知の方法で処理したものを集電体として用いても良い。 The current collector refers to a chemically inert electronic conductor that keeps a current flowing through an electrode during discharge or charging of a lithium ion secondary battery. The material of the current collector is not particularly limited as long as it is a metal that can withstand a voltage suitable for the active material to be used. The current collector material is at least one selected from silver, copper, gold, aluminum, tungsten, cobalt, zinc, nickel, iron, platinum, tin, indium, titanium, ruthenium, tantalum, chromium, molybdenum, and stainless steel Examples of such a metal material can be given. The current collector may be covered with a known protective layer. A current collector obtained by treating the surface of a current collector by a known method may be used as the current collector.
　正極の電位をリチウム基準で４Ｖ以上とする場合には、正極用集電体としてアルミニウムを採用するのが好ましい。 When the potential of the positive electrode is 4 V or higher with respect to lithium, it is preferable to employ aluminum as the positive electrode current collector.
　具体的には、正極用集電体として、アルミニウム又はアルミニウム合金からなるものを用いるのが好ましい。ここでアルミニウムは、純アルミニウムを指し、純度９９．０％以上のアルミニウムを純アルミニウムと称する。純アルミニウムに種々の元素を添加して合金としたものをアルミニウム合金と称する。アルミニウム合金としては、Ａｌ－Ｃｕ系、Ａｌ－Ｍｎ系、Ａｌ－Ｆｅ系、Ａｌ－Ｓｉ系、Ａｌ－Ｍｇ系、Ａｌ－Ｍｇ－Ｓｉ系、Ａｌ－Ｚｎ－Ｍｇ系が挙げられる。 Specifically, it is preferable to use a material made of aluminum or an aluminum alloy as the positive electrode current collector. Here, aluminum refers to pure aluminum, and aluminum having a purity of 99.0% or more is referred to as pure aluminum. An alloy obtained by adding various elements to pure aluminum is referred to as an aluminum alloy. Examples of the aluminum alloy include Al—Cu, Al—Mn, Al—Fe, Al—Si, Al—Mg, Al—Mg—Si, and Al—Zn—Mg.
　また、アルミニウム又はアルミニウム合金として、具体的には、例えばＪＩＳ　Ａ１０８５、Ａ１Ｎ３０等のＡ１０００系合金（純アルミニウム系)、ＪＩＳ　Ａ３００３、Ａ３００４等のＡ３０００系合金（Ａｌ－Ｍｎ系）、ＪＩＳ　Ａ８０７９、Ａ８０２１等のＡ８０００系合金（Ａｌ－Ｆｅ系）が挙げられる。 Specific examples of aluminum or aluminum alloy include A1000 series alloys (pure aluminum series) such as JIS A1085 and A1N30, A3000 series alloys (Al-Mn series) such as JIS A3003 and A3004, JIS A8079, A8021, etc. A8000-based alloy (Al-Fe-based).
　集電体は箔、シート、フィルム、線状、棒状、メッシュなどの形態をとることができる。そのため、集電体として、例えば、銅箔、ニッケル箔、アルミニウム箔、ステンレス箔などの金属箔を好適に用いることができる。集電体が箔、シート、フィルム形態の場合は、その厚みが１μｍ～１００μｍの範囲内であることが好ましい。 The current collector can take the form of a foil, a sheet, a film, a linear shape, a rod shape, a mesh, or the like. Therefore, for example, a metal foil such as a copper foil, a nickel foil, an aluminum foil, and a stainless steel foil can be suitably used as the current collector. When the current collector is in the form of foil, sheet or film, the thickness is preferably in the range of 1 μm to 100 μm.
　正極活物質層には、本発明の正極活物質以外に公知の正極活物質が含まれていてもよい。また、正極活物質層には、結着剤及び導電助剤が含まれているのが好ましい。正極活物質層に含まれる結着剤及び導電助剤としては、後述の負極で説明するものを適宜適切に採用すればよい。 The positive electrode active material layer may contain a known positive electrode active material in addition to the positive electrode active material of the present invention. Further, the positive electrode active material layer preferably contains a binder and a conductive additive. As the binder and the conductive assistant contained in the positive electrode active material layer, those described in the later-described negative electrode may be appropriately employed.
　本発明のリチウムイオン二次電池は、具体的に、本発明の正極と、負極と、電解液と、セパレータとを具備する。負極は、集電体と集電体上に形成された負極活物質層を具備する。負極活物質層には、公知の負極活物質が含まれる。負極の集電体としては、本発明の正極で説明したものから適宜適切に選択すればよい。以下、正極活物質及び負極活物質の両者を総合して「活物質」という場合があり、また、正極活物質層及び負極活物質層の両者を総合して「活物質層」という場合がある。 The lithium ion secondary battery of the present invention specifically includes the positive electrode, the negative electrode, the electrolytic solution, and the separator of the present invention. The negative electrode includes a current collector and a negative electrode active material layer formed on the current collector. The negative electrode active material layer includes a known negative electrode active material. The current collector for the negative electrode may be appropriately selected from those described for the positive electrode of the present invention. Hereinafter, the positive electrode active material and the negative electrode active material may be collectively referred to as “active material”, and the positive electrode active material layer and the negative electrode active material layer may be collectively referred to as “active material layer”. .
　結着剤としては、ポリフッ化ビニリデン、ポリテトラフルオロエチレン、フッ素ゴム等の含フッ素樹脂、ポリプロピレン、ポリエチレン等の熱可塑性樹脂、ポリイミド、ポリアミドイミド等のイミド系樹脂、アルコキシシリル基含有樹脂、カルボキシメチルセルロース、スチレンブタジエンゴムなどの公知のものを採用すればよい。 Examples of the binder include fluorine-containing resins such as polyvinylidene fluoride, polytetrafluoroethylene, and fluororubber, thermoplastic resins such as polypropylene and polyethylene, imide resins such as polyimide and polyamideimide, alkoxysilyl group-containing resins, and carboxymethylcellulose. What is necessary is just to employ | adopt well-known things, such as a styrene butadiene rubber.
　活物質層中の結着剤の配合割合は、質量比で、活物質：結着剤＝１：０．００５～１：０．５であるのが好ましい。結着剤が少なすぎると電極の成形性が低下し、また、結着剤が多すぎると電極のエネルギー密度が低くなるためである。 The mixing ratio of the binder in the active material layer is preferably, as a mass ratio, active material: binder = 1: 0.005 to 1: 0.5. This is because when the amount of the binder is too small, the moldability of the electrode is lowered, and when the amount of the binder is too large, the energy density of the electrode is lowered.
　導電助剤は、電極の導電性を高めるために添加される。そのため、導電助剤は、電極の導電性が不足する場合に任意に加えればよく、電極の導電性が十分に優れている場合には加えなくても良い。導電助剤としては化学的に不活性な電子高伝導体であれば良く、炭素質微粒子であるカーボンブラック、黒鉛、気相法炭素繊維（Vapor Grown Carbon Fiber）、および各種金属粒子などが例示される。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（登録商標）、ファーネスブラック、チャンネルブラックなどが例示される。これらの導電助剤を単独又は二種以上組み合わせて活物質層に添加することができる。活物質層中の導電助剤の配合割合は、質量比で、活物質：導電助剤＝１：０．０１～１：０．７であるのが好ましい。導電助剤が少なすぎると効率のよい導電パスを形成できず、また、導電助剤が多すぎると活物質層の成形性が悪くなるとともに電極のエネルギー密度が低くなるためである。 Conductive aid is added to increase the conductivity of the electrode. Therefore, the conductive auxiliary agent may be added arbitrarily when the electrode conductivity is insufficient, and may not be added when the electrode conductivity is sufficiently excellent. The conductive auxiliary agent may be any chemically inert electronic high conductor, such as carbon black, graphite, vapor grown carbon fiber (Vapor Grown Carbon Fiber), and various metal particles. The Examples of carbon black include acetylene black, ketjen black (registered trademark), furnace black, and channel black. These conductive assistants can be added to the active material layer alone or in combination of two or more. The mixing ratio of the conductive additive in the active material layer is preferably, as a mass ratio, active material: conductive additive = 1: 0.01 to 1: 0.7. This is because if the amount of the conductive auxiliary is too small, an efficient conductive path cannot be formed, and if the amount of the conductive auxiliary is too large, the moldability of the active material layer is deteriorated and the energy density of the electrode is lowered.
　集電体の表面に活物質層を形成させるには、ロールコート法、ダイコート法、ディップコート法、ドクターブレード法、スプレーコート法、カーテンコート法などの従来から公知の方法を用いて、集電体の表面に活物質を塗布すればよい。具体的には、活物質、結着剤、溶剤、並びに必要に応じて導電助剤を混合してスラリーにしてから、当該スラリーを集電体の表面に塗布後、乾燥するとよい。溶剤としては、Ｎ－メチル－２－ピロリドン、メタノール、メチルイソブチルケトン、水を例示できる。電極密度を高めるべく、乾燥後のものを圧縮しても良い。また、活物質、結着剤、及び必要に応じて導電助剤を含む混合物を調製し、当該混合物を集電体に圧着させることで、集電体の表面に活物質層を形成させてもよい。 In order to form an active material layer on the surface of the current collector, a current collecting method such as a roll coating method, a die coating method, a dip coating method, a doctor blade method, a spray coating method, or a curtain coating method can be used. An active material may be applied to the surface of the body. Specifically, an active material, a binder, a solvent, and a conductive additive as necessary are mixed to form a slurry, and the slurry is applied to the surface of the current collector and then dried. Examples of the solvent include N-methyl-2-pyrrolidone, methanol, methyl isobutyl ketone, and water. In order to increase the electrode density, the dried product may be compressed. Alternatively, an active material layer may be formed on the surface of the current collector by preparing a mixture containing an active material, a binder, and if necessary, a conductive additive, and then bonding the mixture to the current collector. Good.
　セパレータは、正極と負極とを隔離し、両極の接触による短絡を防止しつつ、リチウムイオンを通過させるものである。セパレータとしては、公知のものを採用すればよく、ポリテトラフルオロエチレン、ポリプロピレン、ポリエチレン、ポリイミド、ポリアミド、ポリアラミド（Ａｒｏｍａｔｉｃ　ｐｏｌｙａｍｉｄｅ）、ポリエステル及びポリアクリロニトリル等の合成樹脂、セルロース及びアミロース等の多糖類、フィブロイン、ケラチン、リグニン及びスベリン等の天然高分子、並びにセラミックスなどの電気絶縁性材料を、１種若しくは複数用いた多孔体、不織布及び織布などを挙げることができる。また、セパレータは多層構造としてもよい。 The separator separates the positive electrode and the negative electrode and allows lithium ions to pass while preventing a short circuit due to contact between the two electrodes. As the separator, a known separator may be employed, such as polytetrafluoroethylene, polypropylene, polyethylene, polyimide, polyamide, polyaramid (Aromatic polymer), polyester, polyacrylonitrile, and other synthetic resins, cellulose, amylose, and other polysaccharides, fibroin. , Porous materials, nonwoven fabrics, woven fabrics, and the like using one or more natural polymers such as keratin, lignin and suberin, and ceramics and other electrically insulating materials. The separator may have a multilayer structure.
　電解液は、非水溶媒と非水溶媒に溶解した電解質とを含んでいる。 The electrolytic solution contains a non-aqueous solvent and an electrolyte dissolved in the non-aqueous solvent.
　非水溶媒としては、環状カーボネート、環状エステル、鎖状カーボネート、鎖状エステル、エーテル類等が使用できる。環状カーボネートとしては、エチレンカーボネート、プロピレンカーボネート、ブチレンカーボネート、ビニレンカーボネートを例示でき、環状エステルとしては、ガンマブチロラクトン、２－メチル－ガンマブチロラクトン、アセチル－ガンマブチロラクトン、ガンマバレロラクトンを例示できる。鎖状カーボネートとしては、ジメチルカーボネート、ジエチルカーボネート、ジブチルカーボネート、ジプロピルカーボネート、エチルメチルカーボネートを例示でき、鎖状エステルとしては、プロピオン酸アルキルエステル、マロン酸ジアルキルエステル、酢酸アルキルエステル等を例示できる。エーテル類としては、テトラヒドロフラン、２－メチルテトラヒドロフラン、１，４－ジオキサン、１，２－ジメトキシエタン、１，２－ジエトキシエタン、１，２－ジブトキシエタンを例示できる。非水溶媒としては、上記具体的な溶媒の化学構造のうち一部又は全部の水素がフッ素に置換した化合物を採用しても良い。 As the non-aqueous solvent, cyclic carbonates, cyclic esters, chain carbonates, chain esters, ethers and the like can be used. Examples of the cyclic carbonate include ethylene carbonate, propylene carbonate, butylene carbonate, and vinylene carbonate, and examples of the cyclic ester include gamma butyrolactone, 2-methyl-gamma butyrolactone, acetyl-gamma butyrolactone, and gamma valerolactone. Examples of the chain carbonate include dimethyl carbonate, diethyl carbonate, dibutyl carbonate, dipropyl carbonate, and ethyl methyl carbonate. Examples of the chain ester include propionic acid alkyl ester, malonic acid dialkyl ester, and acetic acid alkyl ester. Examples of ethers include tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane, 1,2-diethoxyethane, and 1,2-dibutoxyethane. As the non-aqueous solvent, a compound in which part or all of hydrogen in the chemical structure of the specific solvent is substituted with fluorine may be employed.
　電解質としては、ＬｉＣｌＯ４、ＬｉＡｓＦ６、ＬｉＰＦ６、ＬｉＢＦ４、ＬｉＣＦ３ＳＯ３、ＬｉＮ（ＣＦ３ＳＯ２）２等のリチウム塩を例示できる。 Examples of the electrolyte include lithium salts such as LiClO 4 , LiAsF 6 , LiPF 6 , LiBF 4 , LiCF 3 SO 3 , and LiN (CF 3 SO 2 ) 2 .
　電解液としては、フルオロエチレンカーボネート、エチレンカーボネート、ジメチルカーボネート、エチルメチルカーボネート、ジエチルカーボネートなどの非水溶媒に、ＬｉＣｌＯ４、ＬｉＰＦ６、ＬｉＢＦ４、ＬｉＣＦ３ＳＯ３などのリチウム塩を０．５ｍｏｌ／Ｌから１．７ｍｏｌ／Ｌ程度の濃度で溶解させた溶液を例示できる。 As an electrolytic solution, 0.5 mol / liter of a lithium salt such as LiClO 4 , LiPF 6 , LiBF 4 , LiCF 3 SO 3 is added to a non-aqueous solvent such as fluoroethylene carbonate, ethylene carbonate, dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate. A solution dissolved at a concentration of about 1.7 mol / L from L can be exemplified.
　本発明のリチウムイオン二次電池の具体的な製造方法について述べる。
　例えば、正極と負極とでセパレータを挟持して電極体とする。電極体は、正極、セパレータ及び負極を重ねた積層型、又は、正極、セパレータ及び負極の積層体を捲いた捲回型のいずれの型にしても良い。正極の集電体および負極の集電体から外部に通ずる正極端子および負極端子までを、集電用リード等を用いて接続した後に、電極体に電解液を加えてリチウムイオン二次電池とするとよい。 A specific method for producing the lithium ion secondary battery of the present invention will be described.
For example, a separator is sandwiched between a positive electrode and a negative electrode to form an electrode body. The electrode body may be any of a stacked type in which a positive electrode, a separator and a negative electrode are stacked, or a wound type in which a positive electrode, a separator and a negative electrode are stacked. After connecting the positive electrode current collector and the negative electrode current collector to the positive electrode terminal and the negative electrode terminal connected to the outside using a current collecting lead or the like, an electrolyte is added to the electrode body to form a lithium ion secondary battery. Good.
　本発明のリチウムイオン二次電池の形状は特に限定されるものでなく、円筒型、角型、コイン型、ラミネート型等、種々の形状を採用することができる。 The shape of the lithium ion secondary battery of the present invention is not particularly limited, and various shapes such as a cylindrical shape, a square shape, a coin shape, and a laminate shape can be adopted.
　本発明のリチウムイオン二次電池は、車両に搭載してもよい。車両は、その動力源の全部あるいは一部にリチウムイオン二次電池による電気エネルギーを使用している車両であればよく、例えば、電気車両、ハイブリッド車両などであるとよい。車両にリチウムイオン二次電池を搭載する場合には、リチウムイオン二次電池を複数直列に接続して組電池とするとよい。リチウムイオン二次電池を搭載する機器としては、車両以外にも、パーソナルコンピュータ、携帯通信機器など、電池で駆動される各種の家電製品、オフィス機器、産業機器などが挙げられる。さらに、本発明のリチウムイオン二次電池は、風力発電、太陽光発電、水力発電その他電力系統の蓄電装置及び電力平滑化装置、船舶等の動力及び／又は補機類の電力供給源、航空機、宇宙船等の動力及び／又は補機類の電力供給源、電気を動力源に用いない車両の補助用電源、移動式の家庭用ロボットの電源、システムバックアップ用電源、無停電電源装置の電源、電動車両用充電ステーションなどにおいて充電に必要な電力を一時蓄える蓄電装置に用いてもよい。 The lithium ion secondary battery of the present invention may be mounted on a vehicle. The vehicle may be a vehicle that uses electric energy generated by a lithium ion secondary battery for all or a part of its power source. For example, the vehicle may be an electric vehicle or a hybrid vehicle. When a lithium ion secondary battery is mounted on a vehicle, a plurality of lithium ion secondary batteries may be connected in series to form an assembled battery. Examples of devices equipped with lithium ion secondary batteries include various home appliances driven by batteries such as personal computers and portable communication devices, office devices, and industrial devices in addition to vehicles. Furthermore, the lithium ion secondary battery of the present invention includes wind power generation, solar power generation, hydroelectric power generation and other power system power storage devices and power smoothing devices, power supplies for ships and / or auxiliary power supply sources, aircraft, Power supply for spacecraft and / or auxiliary equipment, auxiliary power supply for vehicles that do not use electricity as a power source, power supply for mobile home robots, power supply for system backup, power supply for uninterruptible power supply, You may use for the electrical storage apparatus which stores temporarily the electric power required for charge in the charging station for electric vehicles.
　以上、本発明の実施形態を説明したが、本発明は、上記実施形態に限定されるものではない。本発明の要旨を逸脱しない範囲において、当業者が行い得る変更、改良等を施した種々の形態にて実施することができる。 As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment. The present invention can be implemented in various forms without departing from the gist of the present invention, with modifications and improvements that can be made by those skilled in the art.
　以下に、各種の具体例を示し、本発明をより具体的に説明する。なお、本発明は、これらの具体例によって限定されるものではない。 Hereinafter, various specific examples will be shown to describe the present invention more specifically. The present invention is not limited to these specific examples.
（実施例１－１）
　Ｌｉ２ＣＯ３、Ｎｂ２Ｏ５、Ｍｎ２Ｏ３及びＭｇ(ＮＯ３)２・６Ｈ２Ｏを、Ｌｉ：Ｎｂ：Ｍｎ：Ｍｇが１．２２５：０．２７５：０．４：０．１となる比率で秤量し、これらの粉末をボールミルに投入した。粉末全体に対して１質量％のプロピレングリコールを添加した上で、ボールミルによる混合を行い、混合物とした。混合物を成形した上で、アルゴンガス雰囲気下、９５０℃で１２時間加熱することで、焼成物を製造した。焼成物を解砕して、実施例１－１の正極活物質とした。実施例１－１の正極活物質の理論上の組成は、Ｌｉ１．２２５Ｎｂ０．２７５Ｍｎ０．４Ｍｇ０．１Ｏ２である。 Example 1-1
Li 2 CO 3, Nb 2 O 5, Mn 2 O 3 and Mg (NO 3) the 2 · 6H 2 O, Li: Nb: Mn: Mg is 1.225: 0.275: 0.4: 0.1 These powders were weighed at a ratio to give, and these powders were put into a ball mill. After adding 1 mass% propylene glycol with respect to the whole powder, it mixed by the ball mill, and was set as the mixture. After the mixture was molded, it was heated at 950 ° C. for 12 hours under an argon gas atmosphere to produce a fired product. The fired product was crushed to obtain a positive electrode active material of Example 1-1. The theoretical composition of the positive electrode active material of Example 1-1 is Li 1.225 Nb 0.275 Mn 0.4 Mg 0.1 O 2 .
　実施例１－１の正極活物質を５質量部、導電助剤としてアセチレンブラックを３質量部、結着剤としてポリテトラフルオロエチレンを２質量部、及び、適量のＮ－メチル－２－ピロリドンを混合して、スラリーとした。集電体としてアルミニウム箔を準備し、これにスラリーを塗布して、乾燥することで実施例１－１の正極を得た。 5 parts by weight of the positive electrode active material of Example 1-1, 3 parts by weight of acetylene black as a conductive assistant, 2 parts by weight of polytetrafluoroethylene as a binder, and an appropriate amount of N-methyl-2-pyrrolidone Mix to make a slurry. An aluminum foil was prepared as a current collector, and a slurry was applied to the aluminum foil and dried to obtain a positive electrode of Example 1-1.
　リチウム箔を準備し、これを負極とした。セパレータとして厚さ２０μｍのポリエチレン多孔質膜を準備した。また、エチレンカーボネート５体積部及びジエチルカーボネート５体積部を混合した溶媒にＬｉＰＦ6を１ｍｏｌ／Ｌの濃度で溶解した電解液を準備した。セパレータを実施例１－１の正極と負極とで挟持し電極体とした。この電極体をコイン型電池ケースＣＲ２０３２（宝泉株式会社）に収容し、さらに電解液を注入して、密閉型のコイン型電池を得た。これを実施例１－１のリチウムイオン二次電池とした。 Lithium foil was prepared and used as a negative electrode. A polyethylene porous membrane having a thickness of 20 μm was prepared as a separator. Was also prepared LiPF 6 was dissolved in a solvent obtained by mixing 5 parts by volume of ethylene carbonate and diethyl carbonate 5 parts by volume in a concentration of 1 mol / L electrolyte solution. The separator was sandwiched between the positive electrode and the negative electrode of Example 1-1 to obtain an electrode body. This electrode body was accommodated in a coin-type battery case CR2032 (Hosen Co., Ltd.), and an electrolyte was further injected to obtain a sealed coin-type battery. This was designated as the lithium ion secondary battery of Example 1-1.
（実施例１－２）
　Ｌｉ２ＣＯ３、Ｎｂ２Ｏ５、Ｍｎ２Ｏ３及びＭｇ(ＮＯ３)２・６Ｈ２Ｏを、Ｌｉ：Ｎｂ：Ｍｎ：Ｍｇが１．２：０．３：０．３５：０．１となる比率で秤量して用いた以外は、実施例１－１と同様の方法で、実施例１－２の正極活物質、正極及びリチウムイオン二次電池を製造した。実施例１－２の正極活物質の理論上の組成は、Ｌｉ１．２Ｎｂ０．３Ｍｎ０．３５Ｍｇ０．１Ｏ２である。 Example 1-2
Li 2 CO 3 , Nb 2 O 5 , Mn 2 O 3 and Mg (NO 3 ) 2 .6H 2 O, Li: Nb: Mn: Mg 1.2: 0.3: 0.35: 0.1 A positive electrode active material, a positive electrode, and a lithium ion secondary battery of Example 1-2 were produced in the same manner as in Example 1-1, except that they were weighed at a ratio of The theoretical composition of the positive electrode active material of Example 1-2 is Li 1.2 Nb 0.3 Mn 0.35 Mg 0.1 O 2 .
（実施例１－３）
　Ｌｉ２ＣＯ３、Ｎｂ２Ｏ５、Ｍｎ２Ｏ３及びＭｇ(ＮＯ３)２・６Ｈ２Ｏを、Ｌｉ：Ｎｂ：Ｍｎ：Ｍｇが１．１：０．３：０．４：０．１となる比率で秤量して用いた以外は、実施例１－１と同様の方法で、実施例１－３の正極活物質、正極及びリチウムイオン二次電池を製造した。実施例１－３の正極活物質の理論上の組成は、Ｌｉ１．１Ｎｂ０．３Ｍｎ０．４Ｍｇ０．１Ｏ２である。 (Example 1-3)
Li 2 CO 3 , Nb 2 O 5 , Mn 2 O 3 and Mg (NO 3 ) 2 .6H 2 O, Li: Nb: Mn: Mg 1.1: 0.3: 0.4: 0.1 A positive electrode active material, a positive electrode, and a lithium ion secondary battery of Example 1-3 were produced in the same manner as in Example 1-1, except that they were weighed at a ratio of The theoretical composition of the positive electrode active material of Example 1-3 is Li 1.1 Nb 0.3 Mn 0.4 Mg 0.1 O 2 .
（実施例２－１）
　Ｌｉ２ＣＯ３、Ｎｂ２Ｏ５、Ｍｎ２Ｏ３及びＬｉＦを、Ｌｉ：Ｎｂ：Ｍｎ：Ｆが１．２５：０．３：０．４：０．０５となる比率で秤量し、これらの粉末をボールミルに投入した。粉末全体に対して１質量％のプロピレングリコールを添加した上で、ボールミルによる混合を行い、混合物とした。混合物を成形した上で、アルゴンガス雰囲気下、９５０℃で１２時間加熱することで、焼成物を製造した。焼成物を解砕して、実施例２－１の正極活物質とした。以下、実施例１－１と同様の方法で、実施例２－１の正極及びリチウムイオン二次電池を製造した。実施例２－１の正極活物質の理論上の組成は、Ｌｉ１．２５Ｎｂ０．３Ｍｎ０．４Ｏ１．９５Ｆ０．０５である。 Example 2-1
Li 2 CO 3 , Nb 2 O 5 , Mn 2 O 3 and LiF were weighed at a ratio of Li: Nb: Mn: F of 1.25: 0.3: 0.4: 0.05, and these The powder was put into a ball mill. After adding 1 mass% propylene glycol with respect to the whole powder, it mixed by the ball mill, and was set as the mixture. After the mixture was molded, it was heated at 950 ° C. for 12 hours under an argon gas atmosphere to produce a fired product. The fired product was crushed to obtain a positive electrode active material of Example 2-1. Thereafter, the positive electrode and the lithium ion secondary battery of Example 2-1 were produced in the same manner as in Example 1-1. The composition of the theoretical positive electrode active material in Example 2-1 is a Li 1.25 Nb 0.3 Mn 0.4 O 1.95 F 0.05.
（実施例２－２）
　Ｌｉ２ＣＯ３、Ｎｂ２Ｏ５、Ｍｎ２Ｏ３及びＬｉＦを、Ｌｉ：Ｎｂ：Ｍｎ：Ｆが１．２：０．３：０．４：０．１となる比率で秤量して用いた以外は、実施例２－１と同様の方法で、実施例２－２の正極活物質、正極及びリチウムイオン二次電池を製造した。実施例２－２の正極活物質の理論上の組成は、Ｌｉ１．２Ｎｂ０．３Ｍｎ０．４Ｏ１．９Ｆ０．１である。 (Example 2-2)
Li 2 CO 3 , Nb 2 O 5 , Mn 2 O 3 and LiF were weighed and used at a ratio such that Li: Nb: Mn: F was 1.2: 0.3: 0.4: 0.1. A positive electrode active material, a positive electrode, and a lithium ion secondary battery of Example 2-2 were produced in the same manner as in Example 2-1, except for the above. The theoretical composition of the positive electrode active material of Example 2-2 is Li 1.2 Nb 0.3 Mn 0.4 O 1.9 F 0.1 .
（比較例１）
　Ｍｇ(ＮＯ３)２・６Ｈ２Ｏを使用せず、Ｌｉ２ＣＯ３、Ｎｂ２Ｏ５及びＭｎ２Ｏ３を、Ｌｉ：Ｎｂ：Ｍｎが１．３：０．３：０．４となる比率で秤量して用いた以外は、実施例１－１と同様の方法で、比較例１の正極活物質、正極及びリチウムイオン二次電池を製造した。比較例１の正極活物質の理論上の組成は、Ｌｉ１．３Ｎｂ０．３Ｍｎ０．４Ｏ２である。 (Comparative Example 1)
Without using Mg (NO 3 ) 2 .6H 2 O, Li 2 CO 3 , Nb 2 O 5 and Mn 2 O 3 become Li: Nb: Mn 1.3: 0.3: 0.4 A positive electrode active material, a positive electrode, and a lithium ion secondary battery of Comparative Example 1 were produced in the same manner as in Example 1-1, except that they were weighed in proportions. The theoretical composition of the positive electrode active material of Comparative Example 1 is Li 1.3 Nb 0.3 Mn 0.4 O 2 .
（評価例１）
　走査型電子顕微鏡（ＳＥＭ）とエネルギー分散型Ｘ線分析装置（ＥＤＸ）を組み合わせたＳＥＭ－ＥＤＸにて、実施例１－１及び実施例２－１の正極活物質の分析を行った。実施例１－１の正極活物質からはＭｇの存在が確認され、また、実施例２－１の正極活物質からはＦの存在が確認された。 (Evaluation example 1)
The positive electrode active materials of Example 1-1 and Example 2-1 were analyzed by SEM-EDX in which a scanning electron microscope (SEM) and an energy dispersive X-ray analyzer (EDX) were combined. The presence of Mg was confirmed from the positive electrode active material of Example 1-1, and the presence of F was confirmed from the positive electrode active material of Example 2-1.
（評価例２）
　Ｃｕ－Ｋα線を用いた粉末Ｘ線回折装置にて、実施例１－２、実施例２－２及び比較例１の正極活物質の分析を行った。Ｘ線回折チャートを図１に示す。いずれの正極活物質も、ＮａＣｌ型結晶構造に帰属可能な回折パターンを示した。 (Evaluation example 2)
The positive electrode active materials of Example 1-2, Example 2-2, and Comparative Example 1 were analyzed with a powder X-ray diffractometer using Cu—Kα rays. An X-ray diffraction chart is shown in FIG. All of the positive electrode active materials showed diffraction patterns that could be assigned to the NaCl type crystal structure.
（評価例３）
　各リチウムイオン二次電池につき、６０℃の条件下、電圧が４．６Ｖとなるまで充電し、電圧が１．５Ｖとなるまで放電するとの充放電サイクルを１０サイクル繰り返した。容量維持率を以下の式で算出した。結果を、正極活物質の組成比とともに、表１及び表２に示す。
　容量維持率（％）＝１００×（１０サイクル目の放電容量）／（１サイクル目の放電容量） (Evaluation example 3)
Each lithium ion secondary battery was charged at a temperature of 60 ° C. until the voltage reached 4.6V and discharged / charged until the voltage reached 1.5V, and the charge / discharge cycle was repeated 10 cycles. The capacity maintenance rate was calculated by the following formula. The results are shown in Tables 1 and 2 together with the composition ratio of the positive electrode active material.
Capacity retention rate (%) = 100 × (discharge capacity at 10th cycle) / (discharge capacity at 1st cycle)
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　表１及び表２の結果から、各実施例のリチウムイオン二次電池は、比較例１のリチウムイオン二次電池と比較して、著しく容量維持率に優れるといえる。以上の結果から、本発明の正極活物質に因り、容量維持率に優れるリチウムイオン二次電池を提供できることが裏付けられたといえる。 From the results shown in Tables 1 and 2, it can be said that the lithium ion secondary batteries of each example are remarkably superior in capacity retention compared to the lithium ion secondary battery of Comparative Example 1. From the above results, it can be said that the lithium ion secondary battery having an excellent capacity retention rate can be provided by the positive electrode active material of the present invention.

Claims (7)

  1. 　下記組成式（１）で表され、
    　Ｌｉ１＋ｘＮｂｙＦｅａＭｎｂＡｃＯ２―ｄＦｄ　　　（１）
    　ＡはＢｅ、Ｍｇ、Ｃａ、Ｓｒ、Ｂａ、Ｒａ、Ｓｃ、Ｙ、Ｔｉ、Ｚｒ、Ａｌから選択され、
    　ｘは、０＜ｘ＜１を満足し、
    　ｙは、０＜ｙ＜０．５を満足し、
    　ａ及びｂは、０．２５≦ａ＋ｂ＜１、０≦ａ＜１、０≦ｂ＜１を満足し、
    　ｃは、０≦ｃ≦０．２を満足し、
    　ｄは、０≦ｄ≦０．２を満足し、
    　ただし、ｃ及びｄは同時に０ではないことを特徴とする正極活物質。     It is represented by the following composition formula (1),
    Li 1 + x Nb y Fe a Mn b A c O 2-d F d (1)
    A is selected from Be, Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Al,
    x satisfies 0 <x <1,
    y satisfies 0 <y <0.5,
    a and b satisfy 0.25 ≦ a + b <1, 0 ≦ a <1, 0 ≦ b <1,
    c satisfies 0 ≦ c ≦ 0.2;
    d satisfies 0 ≦ d ≦ 0.2,
    However, the positive electrode active material characterized by c and d being not 0 simultaneously.
  2. 　ｙ、ａ及びｂは、０．８≦２ｙ＋ａ＋ｂ≦１．２を満足する請求項１に記載の正極活物質。 2. The positive electrode active material according to claim 1, wherein y, a, and b satisfy 0.8 ≦ 2y + a + b ≦ 1.2.
  3. 　前記組成式（１）が下記組成式（１－１）で表され、
    　Ｌｉ１＋ｘＮｂｙＦｅａＭｎｂＡｃＯ２　　　（１－１）
    　ＡはＢｅ、Ｍｇ、Ｃａ、Ｓｒ、Ｂａ、Ｒａ、Ｓｃ、Ｙ、Ｔｉ、Ｚｒ、Ａｌから選択され、
    　ｘは、０＜ｘ＜１を満足し、
    　ｙは、０＜ｙ＜０．５を満足し、
    　ａ及びｂは、０．２５≦ａ＋ｂ＜１、０≦ａ＜１、０≦ｂ＜１を満足し、
    　ｃは、０＜ｃ≦０．２を満足する請求項１又は２に記載の正極活物質。     The composition formula (1) is represented by the following composition formula (1-1),
    Li 1 + x Nb y Fe a Mn b Ac O 2 (1-1)
    A is selected from Be, Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Al,
    x satisfies 0 <x <1,
    y satisfies 0 <y <0.5,
    a and b satisfy 0.25 ≦ a + b <1, 0 ≦ a <1, 0 ≦ b <1,
    The positive electrode active material according to claim 1, wherein c satisfies 0 <c ≦ 0.2.
  4. 　前記組成式（１）が下記組成式（１－２）で表され、
    　Ｌｉ１＋ｘＮｂｙＦｅａＭｎｂＯ２―ｄＦｄ　　　（１－２）
    　ｘは、０＜ｘ＜１を満足し、
    　ｙは、０＜ｙ＜０．５を満足し、
    　ａ及びｂは、０．２５≦ａ＋ｂ＜１、０≦ａ＜１、０≦ｂ＜１を満足し、
    　ｄは、０＜ｄ≦０．２を満足する請求項１又は２に記載の正極活物質。     The composition formula (1) is represented by the following composition formula (1-2),
    Li 1 + x Nb y Fe a Mn b O 2-d F d (1-2)
    x satisfies 0 <x <1,
    y satisfies 0 <y <0.5,
    a and b satisfy 0.25 ≦ a + b <1, 0 ≦ a <1, 0 ≦ b <1,
    The positive electrode active material according to claim 1, wherein d satisfies 0 <d ≦ 0.2.
  5. 　前記組成式（１）が下記組成式（１－３）で表され、
    　Ｌｉ１＋ｘＮｂｙＦｅａＭｎｂＡｃＯ２―ｄＦｄ　　　（１－３）
    　ＡはＢｅ、Ｍｇ、Ｃａ、Ｓｒ、Ｂａ、Ｒａ、Ｓｃ、Ｙ、Ｔｉ、Ｚｒ、Ａｌから選択され、
    　ｘは、０＜ｘ＜１を満足し、
    　ｙは、０＜ｙ＜０．５を満足し、
    　ａ及びｂは、０．２５≦ａ＋ｂ＜１、０≦ａ＜１、０≦ｂ＜１を満足し、
    　ｃは、０＜ｃ≦０．２を満足し、
    　ｄは、０＜ｄ≦０．２を満足する請求項１又は２に記載の正極活物質。     The composition formula (1) is represented by the following composition formula (1-3),
    Li 1 + x Nb y Fe a Mn b A c O 2 -d F d (1-3)
    A is selected from Be, Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Al,
    x satisfies 0 <x <1,
    y satisfies 0 <y <0.5,
    a and b satisfy 0.25 ≦ a + b <1, 0 ≦ a <1, 0 ≦ b <1,
    c satisfies 0 <c ≦ 0.2;
    The positive electrode active material according to claim 1, wherein d satisfies 0 <d ≦ 0.2.
  6. 　請求項１～５のいずれか１項に記載の正極活物質を具備するリチウムイオン二次電池用正極。 A positive electrode for a lithium ion secondary battery comprising the positive electrode active material according to any one of claims 1 to 5.
  7. 　請求項１～５のいずれか１項に記載の正極活物質を具備するリチウムイオン二次電池。 A lithium ion secondary battery comprising the positive electrode active material according to any one of claims 1 to 5.
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JP2001126729A (en) * 1999-10-28 2001-05-11 Toshiba Corp Nonaqueous electrolytic secondary cell
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