WO2012124242A1 - Cathode active material for non-aqueous electrolyte secondary battery, method for producing same, and non-aqueous electrolyte secondary battery using same - Google Patents

Cathode active material for non-aqueous electrolyte secondary battery, method for producing same, and non-aqueous electrolyte secondary battery using same Download PDF

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WO2012124242A1
WO2012124242A1 PCT/JP2012/000084 JP2012000084W WO2012124242A1 WO 2012124242 A1 WO2012124242 A1 WO 2012124242A1 JP 2012000084 W JP2012000084 W JP 2012000084W WO 2012124242 A1 WO2012124242 A1 WO 2012124242A1
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nickel
lithium
active material
positive electrode
raw material
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Japanese (ja)
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祐樹 杉本
直人 安田
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株式会社豊田自動織機
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/364—Composites as mixtures
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    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G45/00—Compounds of manganese
    • C01G45/12—Manganates manganites or permanganates
    • C01G45/1221—Manganates or manganites with a manganese oxidation state of Mn(III), Mn(IV) or mixtures thereof
    • C01G45/125—Manganates or manganites with a manganese oxidation state of Mn(III), Mn(IV) or mixtures thereof of the type[MnO3]n-, e.g. Li2MnO3, Li2[MxMn1-xO3], (La,Sr)MnO3
    • C01G45/1257—Manganates or manganites with a manganese oxidation state of Mn(III), Mn(IV) or mixtures thereof of the type[MnO3]n-, e.g. Li2MnO3, Li2[MxMn1-xO3], (La,Sr)MnO3 containing lithium, e.g. Li2MnO3, Li2[MxMn1-xO3
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G53/00—Compounds of nickel
    • C01G53/40—Nickelates
    • C01G53/42—Nickelates containing alkali metals, e.g. LiNiO2
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G53/00—Compounds of nickel
    • C01G53/40—Nickelates
    • C01G53/42—Nickelates containing alkali metals, e.g. LiNiO2
    • C01G53/44—Nickelates containing alkali metals, e.g. LiNiO2 containing manganese
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    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G53/00—Compounds of nickel
    • C01G53/40—Nickelates
    • C01G53/42—Nickelates containing alkali metals, e.g. LiNiO2
    • C01G53/44—Nickelates containing alkali metals, e.g. LiNiO2 containing manganese
    • C01G53/50—Nickelates containing alkali metals, e.g. LiNiO2 containing manganese of the type [MnO2]n-, e.g. Li(NixMn1-x)O2, Li(MyNixMn1-x-y)O2
    • 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
    • C—CHEMISTRY; METALLURGY
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    • C01P2002/50—Solid solutions
    • C01P2002/52—Solid solutions containing elements as dopants
    • C01P2002/54—Solid solutions containing elements as dopants one element only
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    • C01P2002/70—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data
    • C01P2002/72—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data by d-values or two theta-values, e.g. as X-ray diagram
    • C—CHEMISTRY; METALLURGY
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    • C01P2002/00—Crystal-structural characteristics
    • C01P2002/70—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data
    • C01P2002/74—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data by peak-intensities or a ratio thereof only
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/60—Particles characterised by their size
    • C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer
    • C—CHEMISTRY; METALLURGY
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    • C01P2004/62—Submicrometer sized, i.e. from 0.1-1 micrometer
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
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    • C—CHEMISTRY; METALLURGY
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    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/40—Electric properties
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2220/00—Batteries for particular applications
    • H01M2220/20—Batteries in motive systems, e.g. vehicle, ship, plane
    • 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 positive electrode active material for a non-aqueous electrolyte secondary battery, a manufacturing method thereof, and a non-aqueous electrolyte secondary battery using the same.
  • lithium composite oxide used as the positive electrode active material for example, a layered rock salt structure lithium cobalt composite oxide (LiCoO 2 ) and a layered rock salt structure lithium nickel composite oxide (for example, LiNiO 2 ) are well known. Yes.
  • lithium cobalt complex oxide uses Co (cobalt), which is a rare metal, as a raw material, there is a concern about resource shortage in the future. Co is expensive and has a large price fluctuation.
  • lithium nickel-based composite oxides with a layered rock salt structure are more abundant and less expensive than lithium cobalt composite oxides. For this reason, a positive electrode active material using a lithium nickel composite oxide has been developed.
  • a technique for forming a surface layer portion made of nickel oxide on the surface of active material particles made of lithium nickel composite oxide there is a technique for forming a surface layer portion made of nickel oxide on the surface of active material particles made of lithium nickel composite oxide.
  • the layered rock-salt lithium-nickel composite oxide is an electrochemically inert disorder called a rock salt domain. It has an area of an array rock salt layer. It is difficult to produce a high-capacity battery with a lithium nickel-based composite oxide having an irregularly arranged rock salt region.
  • the inventor of the present application has made various studies on a lithium nickel-based composite oxide having a layered rock salt structure in order to increase the battery capacity. As a result, it was found that the starting material, heating temperature, conditions, and the like of the lithium nickel composite oxide greatly affect the battery performance.
  • the present invention has been made in view of such circumstances, and an object thereof is to provide a positive electrode active material for a non-aqueous electrolyte secondary battery excellent in battery characteristics, a method for producing the same, and a non-aqueous electrolyte secondary battery.
  • a positive electrode active material for a non-aqueous electrolyte secondary battery according to the present invention includes a lithium-nickel composite oxide containing at least a lithium (Li) element and a nickel (Ni) element and having a crystal structure of a layered rock salt structure, and nickel oxidation
  • the nickel oxide is part of a raw material for producing the lithium nickel composite oxide or a by-product generated from the raw material.
  • the positive electrode active material has a lithium nickel composite oxide having a layered rock salt structure and nickel oxide.
  • the nickel oxide is a part of a raw material for producing a lithium nickel composite oxide or a by-product generated from the raw material. That is, nickel oxide is an impurity generated as a by-product when a lithium nickel-based composite oxide is generated.
  • the raw material for producing the lithium-nickel-based composite oxide includes, for example, a lithium compound raw material containing one or more metal elements essential for lithium (Li) element and one or more metal elements essential for nickel (Ni) element. It consists of nickel compound raw material containing. In producing a lithium nickel composite oxide, a lithium compound raw material and a nickel compound raw material are mixed and heated.
  • a layered rock salt structure containing lithium as a constituent is formed.
  • nickel ions enter the lithium site of the layered rock salt structure and so-called cation mixing occurs.
  • the region becomes locally disordered salt facies (salt domain).
  • the rock salt domain is itself electrochemically inert.
  • nickel ions mixed in the lithium site inhibit the two-dimensional diffusion of lithium ions. For this reason, a rock salt domain reduces the function as a positive electrode active material rapidly. Therefore, in the present invention, heating is terminated before nickel ions diffuse into the lithium sites having a layered rock salt structure, and the amount of nickel ions mixed into the lithium sites is limited. As a result, a lithium nickel composite oxide with little nickel ion mixing is generated.
  • the positive electrode active material thus produced contains nickel oxide (NiO) as an impurity.
  • the positive electrode active material is composed mainly of a lithium nickel composite oxide that undergoes an electrode reaction, and if it contains only a small amount of nickel oxide, it has superior battery characteristics compared to a positive electrode active material obtained by heating for a long time. It can be demonstrated.
  • the method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery according to the present invention is a method for producing the above-described positive electrode active material for a non-aqueous electrolyte secondary battery, which is one or more metal elements essentially containing nickel Selected from a nickel compound raw material containing one or more metal compounds selected from oxides, hydroxides and metal salts, and oxides, hydroxides and metal salts containing one or more metal elements essential for lithium
  • a lithium compound raw material containing one or more metal compounds is heated to react the nickel compound raw material and the lithium compound raw material while leaving the nickel oxide generated from the nickel compound raw material, thereby the lithium nickel composite It has the reaction process of obtaining an oxide.
  • the lithium compound raw material and the nickel compound raw material are heated to produce a lithium nickel composite oxide having a layered rock salt structure while leaving the nickel oxide generated from the nickel compound raw material. For this reason, nickel ions derived from nickel oxide can be prevented from diffusing into the layered rock salt structure of the lithium nickel composite oxide.
  • the positive electrode active material excellent in the battery characteristic can be obtained.
  • a non-aqueous electrolyte secondary battery of the present invention is characterized by including a positive electrode including the positive electrode active material for a non-aqueous electrolyte secondary battery described above, a negative electrode, and a non-aqueous electrolyte.
  • the vehicle of the present invention is characterized by mounting the nonaqueous electrolyte secondary battery described above.
  • the lithium ion battery of the present invention includes the positive electrode active material described above, the battery characteristics are excellent.
  • the positive electrode active material for a non-aqueous electrolyte secondary battery of the present invention a method for producing the same, and a non-aqueous electrolyte secondary battery, not only lithium nickel-based composite oxides but also nickel oxides as impurities are included. Battery characteristics can be improved. According to the vehicle of the present invention, since the nonaqueous electrolyte secondary battery is mounted, a high output can be exhibited.
  • the positive electrode active material for a non-aqueous electrolyte secondary battery of the present invention has a lithium nickel composite oxide and nickel oxide.
  • the lithium nickel composite oxide contains at least a lithium (Li) element and a nickel (Ni) element.
  • the crystal structure of the lithium nickel composite oxide belongs to the layered rock salt structure.
  • the lithium nickel-based composite oxide has a composition formula: xLi 2 M 1 O 3. (1-x) LiNi y M 2 1-y O 2 (0 ⁇ x ⁇ 1, 0 ⁇ y ⁇ 1, M 1 is 4 1 or more types of metal elements in which valent Mn is essential, M 2 is a metal element, and Li in each case, a part of which may be substituted with hydrogen.)
  • the composition is good.
  • LiNi y M 2 1-y O 2 is LiNi y M 2 1-y O 2 or Li 2 M It is a solid solution of 1 O 3 and LiNi y M 2 1-y O 2 (Li 2 M 1 O 3 —LiNi y M 2 1-y O 2 ).
  • Li 2 M 1 O 3 -LiNi y M 2 1-y and O Li 2 M 1 O 3 in the 2 and LiNi y M 2 1-y O 2 may as containing any, the ratio is any Absent.
  • LiNi y M 2 1-y O 2 and Li 2 M 1 O 3 —LiNi y M 2 1-y O 2 are both complex oxides having a layered rock salt structure ( ⁇ -NaFeO 2 type).
  • Li 2 M 1 O 3 has a large battery capacity, and LiNi y M 2 1-y O 2 is said to have excellent battery cycle characteristics.
  • Li 2 M 1 O 3 and LiNi y M 2 1-y O Li 2 M 1 O 3 -LiNi y M 2 1-y O 2 containing both a 2 has a large battery capacity and cycle characteristics of the battery Are better.
  • Li 2 M 1 O 3 can be expressed as the general formula Li (Li 0.33 M 1 0.67 ) O 2 and is said to belong to the same layered crystal structure as LiNi y M 2 1-y O 2. ing. Therefore, xLi 2 M 1 O 3 ⁇ (1-x) LiNi y M 2 1-y O 2 is Li 1.33-x Ni y M 1 0.67-z M 2 x + zy O 2 (M 1 Is one or more metal elements in which tetravalent Mn is essential, M 2 is a metal element, and 0 ⁇ x ⁇ 0.33, 0 ⁇ y ⁇ 1, 0 ⁇ z ⁇ 0.67) There is.
  • M 1 in the li 2 M 1 O 3 is an essential component tetravalent Mn. Most of M 1 is preferably tetravalent Mn, but less than 80% and even less than 50% of the metal elements constituting M 1 may be substituted with other metal elements other than Mn.
  • the metal element other than Mn that can constitute M 1 is, for example, selected from Ni, Al, Co, Fe, Mg, and Ti from the viewpoint of chargeable / dischargeable capacity when an electrode material is used. preferable.
  • the average oxidation number of M 1 may be slightly different from tetravalent, and is allowed to be 3.8 to 4.2.
  • M 2 in the LiNi y M 2 1-y O 2 is a substituting element of Ni site.
  • M 2 is an optional element of the lithium nickel composite oxide.
  • M 2 is a metal element, and is preferably at least one of Al, Mn, Co, Fe, Mg, and Ti, for example.
  • the average oxidation number combining Ni y and M 2 1-y is preferably trivalent.
  • M 2 is a trivalent metal element
  • the valence of Ni is trivalent.
  • Trivalent elements include Co, Al, Mg, Fe, and Sn.
  • M 2 is Mn
  • the valence of Mn as M 2 is tetravalent
  • the valence of Ni is bivalent
  • Mn and Ni as M 2 are included in the same number of moles.
  • Ni x and M 2 1-x combined may be slightly different from trivalent, and is allowed to be 2.8 to 3.2.
  • a part of Li contained in Li 2 M 1 O 3 and LiNi y M 2 1-y O 2 may be substituted with hydrogen (H).
  • H hydrogen
  • 60% or less, further 45% or less in atomic ratio may be substituted with H.
  • LiNi y M 2 1-y O 2 As a lithium nickel-based composite oxide having a basic composition of a composite oxide represented by a composition formula xLi 2 M 1 O 3. (1-x) LiNi y M 2 1-y O 2 and having a layered rock salt structure, for example, When x in the composition formula is 1, Li 2 M 1 O 3 and when x in the composition formula is 0.5, Li 2 M 1 O 3 .LiNi y M 2 1-y O 2 When x in the composition formula is 0, LiNi y M 2 1-y O 2 is obtained.
  • Li 2 M 1 O 3 examples include Li 2 MnO 3.
  • Examples of LiNi y M 2 1-y O 2 include LiNiO 2 , LiNi 1/3 Mn 1/3 Co 1 / such as 3 O 2, LiNi 1/2 Mn 1/2 O 2, LiNi 1/2 Co 1/2 O 2 can be cited.
  • Li 2 M 1 O 3 .LiNi y M 2 1-y O 2 includes Li 2 MnO 3 .LiNiO 2 , Li 2 MnO 3 .LiNi 1/3 Mn 1/3 Co 1/3 O 2 , Li 2 MnO such as 3 ⁇ LiNi 1/2 Mn 1/2 O 2 , Li 2 MnO 3 ⁇ LiNi 1/2 Co 1/2 O 2 can be cited.
  • Ni, Mn, and Co which are constituent elements of the composite oxide listed above, may be replaced with other metal elements.
  • the obtained composite oxide as a whole may have the basic composition as the exemplified oxide, and may slightly deviate from the above composition formula due to unavoidable metal element or oxygen deficiency.
  • the positive electrode active material contains nickel oxide (NiO) as an impurity.
  • the nickel oxide is a by-product generated from a part of the raw material of the lithium nickel composite oxide or the raw material.
  • the nickel oxide in the positive electrode active material is 100 parts by mass, the nickel oxide is preferably contained in an amount of 5 parts by mass to 30 parts by mass. If the nickel oxide is less than 5 parts by mass, cation mixing proceeds and the electric capacity may be reduced. When the nickel oxide exceeds 30 parts by mass, the nickel oxide does not participate in the battery reaction, so that the battery capacity may be reduced.
  • the lower limit of the nickel oxide content is 5 parts by mass, preferably 10 parts by mass, and the upper limit is 30 parts by mass. Part, preferably 15 parts by weight.
  • the surface index (h, k, l) of the lithium nickel-based composite oxide (0,
  • Nickel oxide has a composition of NiO and forms cubic crystals.
  • the lithium nickel-based composite oxide and the nickel oxide each constitute particles.
  • Nickel oxide is a by-product that has not been introduced into the lithium-nickel composite oxide that is the reaction target. For this reason, the nickel oxide exists as a particle separate from the lithium nickel composite oxide. Nickel oxide does not participate in the battery reaction. For this reason, for example, when the surface of the lithium nickel composite oxide is coated with nickel oxide, the battery reaction of the lithium nickel composite oxide may be hindered. Therefore, as in the present invention, the nickel oxide may constitute separate particles from the lithium nickel composite oxide.
  • Cation mixing is a phenomenon that occurs when the raw material of the lithium nickel composite oxide is heated for a long time. Therefore, heating is terminated before cation mixing occurs. Then, it is possible to suppress nickel ions that become an obstacle to the entry / exit of lithium ions from entering the lithium site, resulting in an increase in electrical output and an increase in capacity.
  • Method for producing positive electrode active material for non-aqueous electrolyte secondary battery In producing a positive electrode active material for a nonaqueous electrolyte secondary battery, the lithium compound raw material and the nickel compound raw material are heated to leave the nickel oxide generated from the nickel compound raw material, A reaction step of obtaining a lithium nickel composite oxide by reacting with a nickel compound raw material is performed. Before performing this reaction process, you may perform the mixing process which mixes a lithium compound raw material and a nickel compound raw material, and obtains a raw material mixture.
  • a lithium compound raw material and a nickel compound raw material are mixed to prepare a raw material mixture.
  • the nickel compound raw material has a metal compound containing one or more metal elements essential for nickel, and one kind selected from oxides, hydroxides and metal salts containing one or more metal elements essential for nickel It is preferable to have the above.
  • the lithium compound raw material has a metal compound containing one or more metal elements essential for lithium, and one kind selected from oxides, hydroxides and metal salts containing one or more metal elements essential for lithium It is preferable to have the above.
  • metal salts include nitrates, sulfates, chloride salts, and the like.
  • the lithium compound raw material preferably contains mainly lithium hydroxide. Examples of lithium hydroxide that can be used include LiOH and LiOH.H 2 O. In addition to lithium, the lithium compound raw material may contain a metal element contained in the lithium nickel composite oxide.
  • the nickel compound raw material contains nickel contained in the lithium nickel composite oxide as an essential element.
  • the nickel compound raw material may contain a metal element other than lithium.
  • the nickel oxide in the positive electrode active material is a by-product generated from a part of the nickel compound raw material or the nickel compound raw material.
  • the nickel compound raw material has at least one selected from oxides, hydroxides and metal salts containing such metal elements.
  • metal salts include nitrates, sulfates, chloride salts, and the like.
  • the nickel compound raw material may contain at least one of nickel hydroxide (NiOH), nickel nitrate (Ni (NO 3 ) 2 .6H 2 O), and nickel sulfate (Ni 2 SO 4 .6H 2 O).
  • the nickel compound raw material further includes manganese dioxide (MnO 2 ), dimanganese trioxide (Mn 2 O 3 ), manganese monoxide (MnO), tetra Trimanganese oxide (Mn 3 O 4 ), manganese hydroxide (Mn (OH) 2 ), manganese oxyhydroxide (MnOOH), or the like can be used.
  • the nickel compound raw material further includes cobalt oxide (CoO, Co 3 O 4 ), cobalt nitrate (Co (NO 3 ) 2 ⁇ 6H 2 O), cobalt hydroxide when the composition of the target object contains Co. (Co (OH) 2 ).
  • the valence of Mn in the nickel compound raw material is not necessarily tetravalent. Tetravalent Mn or less may be used. The reason is that, for example, when the reaction step is performed by the molten salt method, the reaction proceeds in a strong oxidation state, so that Mn is tetravalent even if it is divalent or trivalent.
  • the metal elements such as Ni and Co in the nickel compound raw material may also be lower than the oxidation number in the target object.
  • the nickel compound raw material is one or more metal compounds selected from oxides, hydroxides and metal salts containing two or more metal elements (Ni is essential)
  • the raw materials containing these are used. It may be synthesized in advance as a precursor. That is, before the mixing step, it is preferable to perform a precursor synthesis step in which an aqueous solution containing at least two kinds of metal elements is made alkaline to obtain a precipitate.
  • a water-soluble inorganic salt specifically, a nitrate, sulfate, or chloride salt of a metal element is dissolved in water, and the aqueous solution is made alkaline with an alkali metal hydroxide, aqueous ammonia, etc. Is produced as a precipitate.
  • the lithium compound raw material and the nickel compound raw material are mixed to obtain a raw material mixture.
  • a drying step for drying the raw material mixture may be performed.
  • the drying step can be omitted.
  • the raw material mixture prepared as described above is heated, and the raw material mixture is reacted in a state where the nickel oxide generated from the nickel compound raw material is left to obtain a lithium nickel composite oxide.
  • the heating of the raw material mixture in the reaction step produces a target lithium nickel-based composite oxide from the raw material mixture, and nickel oxide as a by-product is formed outside the generated lithium nickel-based composite oxide. Keep it as it remains. That is, before the nickel oxide (NiO) produced from the nickel compound raw material is introduced into the layered rock salt structure of the lithium nickel-based composite oxide or the amount of introduction is small, the heating of the raw material mixture is stopped to react. End.
  • the heating of the raw material mixture in the reaction step is preferably performed by at least one of, for example, a solid phase method, a spray drying method, a hydrothermal method, and a molten salt method.
  • a solid phase method preferably a spray drying method, a hydrothermal method, and a molten salt method.
  • the lithium nickel composite oxide containing nickel oxide (NiO) as a by-product can be generated in a time shorter than the normal reaction time for the formation reaction of the lithium nickel composite oxide.
  • the molten salt method is desirable because the reaction time is relatively short.
  • a mixing step of preparing a raw material mixture by mixing the lithium compound raw material and the nickel compound raw material is performed, and heating of the raw material mixture in the reaction step is preferably performed by a molten salt method.
  • the solid phase method is a method of obtaining a positive electrode active material by mixing and pulverizing raw material powders, drying and compacting as necessary, and heating and firing.
  • each raw material is mixed in a proportion corresponding to the composition of the lithium nickel composite oxide to be manufactured. That is, the raw materials are mixed in such a ratio that each element contained in the raw material has a stoichiometric composition of the lithium nickel composite oxide.
  • the heating temperature of the raw material mixture is preferably 900 ° C. or higher and 1000 ° C. or lower. Moreover, it is preferable that the heating time of a raw material mixture is 8 hours or more and 24 hours or less. Furthermore, the heating temperature is preferably 920 ° C. or higher and 980 ° C. or lower, and the heating time is preferably 12 hours or longer and 18 hours or shorter. When the heating temperature is less than 900 ° C., the production rate of the lithium nickel composite oxide may be lowered. When heating temperature exceeds 1000 degreeC, there exists a possibility that Li may volatilize.
  • the heating time is less than 8 hours, the formation of the lithium nickel composite oxide is insufficient, and when the heating time exceeds 24 hours, the nickel oxide derived from the by-product nickel oxide is converted into the lithium nickel composite oxide. It is introduced into the lithium site of the layered rock salt structure of the object, causing cation mixing, and the diffusion of lithium ions is hindered, and the battery capacity and the battery output may be reduced.
  • the spray drying method is a method in which a raw material powder is dissolved in a liquid to form a solution, the solution is sprayed into the air to form a mist, and the mist solution is heated. In the spray drying method, further heating may be performed later.
  • the heating temperature of the raw material mixture is preferably 500 ° C. or higher and 1000 ° C. or lower.
  • the heating time of the raw material mixture is preferably 3 hours or more and 8 hours or less.
  • the heating temperature is preferably 600 ° C. or more and 700 ° C. or less, and the heating time is preferably 5 hours or more and 8 hours or less.
  • the heating temperature is less than 500 ° C., there is a possibility that the formation of the lithium nickel composite oxide is insufficient, and when it exceeds 1000 ° C., Li may volatilize.
  • the heating time is less than 3 hours, the formation of lithium nickel composite oxide is insufficient, and when the heating time exceeds 8 hours, nickel ions derived from the by-product nickel oxide are converted into lithium nickel composite oxide. Introduced into the lithium site of the product, cation mixing occurs, lithium ions do not easily enter and exit, and the battery capacity and battery output may be reduced.
  • the hydrothermal method is a method in which raw material powder is dissolved in a liquid to form a solution, and the solution is heated under high temperature and high pressure.
  • the heating temperature of the raw material mixture in the hydrothermal method is preferably 120 ° C. or higher and 200 ° C. or lower, and the heating time is preferably 2 hours or longer and 24 hours or shorter. Furthermore, the heating temperature is preferably 150 ° C. or higher and 180 ° C. or lower, and the heating time is preferably 4 hours or longer and 8 hours or shorter.
  • the heating temperature is less than 120 ° C., the valence of Mn may be significantly reduced.
  • the heating time is less than 2 hours, the formation of the lithium nickel composite oxide is insufficient, and when the heating time exceeds 24 hours, the nickel oxide derived from the nickel oxide as a by-product becomes lithium nickel composite.
  • the lithium is introduced into the lithium site, cation mixing occurs, lithium ions do not easily enter and exit, and the battery capacity and battery output may be reduced.
  • the molten salt method is a method in which a raw material mixture is heated to melt a lithium compound raw material to form a molten salt, and a nickel compound raw material is synthesized in the melt.
  • the lithium compound raw material plays a role in adjusting not only the Li supply source but also the oxidizing power of the molten salt.
  • the ratio of the theoretical composition of Li contained in the target lithium nickel composite oxide (Li of lithium nickel composite oxide / Li of lithium compound raw material) to Li contained in the lithium compound raw material is less than 1 in molar ratio. I just need it.
  • the ratio is preferably 0.02 or more and less than 0.7, more preferably 0.03 to 0.5, or 0.04 to 0.25.
  • the ratio is less than 0.02, the amount of lithium nickel-based composite oxide generated with respect to the amount of the raw material lithium compound raw material is reduced, which is not desirable in terms of production efficiency.
  • the ratio is 0.7 or more, the amount of the lithium compound raw material (molten salt) in which the nickel compound raw material is dispersed is insufficient, and Li cannot be supplied to all the composite oxides.
  • a recovery step of recovering the lithium nickel composite oxide may be performed.
  • the recovery process is not particularly limited, but the lithium nickel composite oxide produced in the reaction process is insoluble in water. Therefore, the raw material mixture after the reaction is sufficiently cooled and solidified to form a solid. Lithium nickel-based composite oxide is obtained as an insoluble matter by dissolving in The filtrate obtained by filtering the aqueous solution may be dried to take out the lithium nickel composite oxide.
  • the recovery step may be a step of recovering the lithium nickel composite oxide after slowly cooling the raw material mixture after the reaction step. That is, after the reaction step, it is preferable to perform a recovery step in which the lithium nickel composite oxide is slowly cooled and recovered.
  • the high-temperature raw material mixture after completion of the reaction may be left in a heating furnace and cooled, or may be taken out of the heating furnace and air-cooled at room temperature.
  • the temperature of the raw material mixture after the reaction step is 2 ° C./min to 50 ° C./min, further 3 to 25 until the temperature of the raw material mixture reaches 450 ° C. or lower (that is, the raw material mixture after the reaction solidifies). It is preferable to cool at a rate of ° C / min. Thereby, a lithium nickel composite oxide having high crystallinity can be obtained, which is particularly advantageous for the synthesis of a lithium nickel composite oxide having a layered rock salt structure.
  • a proton substitution step of substituting part of Li of the lithium nickel composite oxide with hydrogen (H) may be performed.
  • a part of Li is easily substituted with H by bringing the composite oxide after the collection step into contact with a solvent such as diluted acid.
  • a heat treatment step of heating the lithium nickel composite oxide in an oxygen-containing atmosphere may be performed.
  • the heat treatment step is preferably performed in an oxygen-containing atmosphere, for example, in the air, in a gas atmosphere containing oxygen gas and / or ozone gas.
  • the oxygen gas concentration may be 20 to 100% by volume, and more preferably 50 to 100% by volume.
  • the heating temperature is preferably 300 ° C. or higher, more preferably 350 to 500 ° C. This heating temperature is preferably maintained for 20 minutes or more, more preferably 0.5 to 2 hours.
  • the lithium nickel composite oxide contained in the positive electrode active material obtained by the production method of the present invention described in detail above has a particle shape.
  • the primary particles of the lithium nickel composite oxide are single crystals. It can be confirmed by a high-resolution image of a transmission electron microscope (TEM) that the primary particles are single crystals.
  • the half-value width, the plane index of the lithium nickel composite oxide (h, k, l) intensity of a peak indicating the a (0,0,1) when the I max, in the position of I max / 2
  • the smaller primary particle size is likely to be activated.
  • the crystal structure is liable to collapse due to charge / discharge, and the battery characteristics may be deteriorated.
  • the positive electrode active material obtained by the production method of the present invention contains a small amount of nickel oxide (NiO) as a by-product.
  • Non-aqueous electrolyte secondary battery A nonaqueous electrolyte secondary battery using the positive electrode active material for a nonaqueous electrolyte secondary battery of the present invention will be described.
  • the nonaqueous electrolyte secondary battery mainly includes a positive electrode, a negative electrode, and a nonaqueous electrolyte. Moreover, the separator pinched
  • the positive electrode includes a positive electrode active material capable of inserting / extracting lithium ions and a binder that binds the positive electrode active material. Further, a conductive aid may be included.
  • the positive electrode active material the above complex oxide may be used alone.
  • the positive electrode active material includes one or more other positive electrode active materials selected from LiCoO 2 , LiMn 2 O 4 , S, and the like used in general nonaqueous electrolyte secondary batteries, in addition to the above composite oxide. But you can.
  • the binder and the conductive additive are not particularly limited as long as they can be used in a general non-aqueous electrolyte secondary battery.
  • the conductive aid is for ensuring the electrical conductivity of the electrode, and for example, a mixture of one or more carbon material powders such as carbon black, acetylene black, and graphite may be used. it can.
  • the binder plays a role of connecting the positive electrode active material and the conductive additive.
  • the binder that can be used include fluorine-containing resins such as polyvinylidene fluoride, polytetrafluoroethylene, and fluororubber, and thermoplastic resins such as polypropylene and polyethylene.
  • the negative electrode facing the positive electrode has a negative electrode active material.
  • the negative electrode can be formed by forming a sheet of metal lithium, which is a negative electrode active material, or pressing the sheet into a current collector network such as nickel or stainless steel.
  • a lithium alloy or a lithium compound raw material can be used instead of metallic lithium.
  • the negative electrode active material for example, a natural graphite, artificial graphite, an organic compound heating body such as a phenol resin, or a carbonaceous powder such as coke can be used.
  • a negative electrode active material is good to consist of an element compound which can occlude / release lithium ion and has an element which can be alloyed with lithium, and / or an element which can be alloyed with lithium.
  • Elements that can be alloyed with lithium are Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, Ra, Ti, Ag, Zn, Cd, Al, Ga, In, Si, Ge, Sn. , Pb, Sb, Bi may be included.
  • the binder as in the positive electrode, a fluorine-containing resin, a thermoplastic resin, or the like can be used.
  • a secondary battery using metallic lithium or a lithium alloy as the negative electrode active material is referred to as a lithium secondary battery, and when a negative electrode active material other than that is used, it is referred to as a lithium ion secondary battery.
  • the positive electrode and the negative electrode are composed of an active material layer in which each of the positive electrode active material or the negative electrode active material is bound with a binder, and a current collector covered with the active material layer. Therefore, a positive electrode and a negative electrode are prepared by preparing an electrode mixture layer forming composition containing an active material, a binder, and, if necessary, a conductive additive, and further adding a suitable solvent to make a paste, After coating on the surface of the film, it can be dried and, if necessary, compressed to increase the electrode density.
  • the current collector can be a metal mesh or metal foil.
  • the current collector includes a porous or non-porous conductive substrate made of a metal material such as stainless steel, titanium, nickel, aluminum, copper, or a conductive resin.
  • the porous conductive substrate include a mesh body, a net body, a punching sheet, a lath body, a porous body, a foamed body, a fiber group molded body such as a nonwoven fabric, and the like.
  • the non-porous conductive substrate include a foil, a sheet, and a film.
  • a conventionally known method such as a doctor blade or a bar coater may be used.
  • NMP N-methyl-2-pyrrolidone
  • MIBK methyl isobutyl ketone
  • an organic solvent-based electrolytic solution in which an electrolyte is dissolved in an organic solvent, a polymer electrolyte in which the electrolytic solution is held in a polymer, or the like can be used.
  • the organic solvent contained in the electrolytic solution or polymer electrolyte is not particularly limited, but it preferably contains a chain ester from the viewpoint of load characteristics.
  • chain esters include chain carbonates typified by dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate, and organic solvents such as ethyl acetate and methyl propionate. These chain esters may be used alone or in admixture of two or more.
  • the above-mentioned chain esters occupy 50% by volume or more in the total organic solvent.
  • the organic solvent it is preferable to use a mixture having a high induction rate (induction rate: 30 or more) ester in the chain ester, in order to improve the discharge capacity, rather than using only the chain ester.
  • ester include cyclic carbonates typified by ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, ⁇ -butyrolactone, ethylene glycol sulfite, and the like.
  • a cyclic ester such as carbonate is preferred.
  • Such an ester having a high dielectric constant is preferably contained in an amount of 10% by volume or more, particularly 20% by volume or more in the total organic solvent from the viewpoint of discharge capacity.
  • 40 volume% or less is preferable and 30 volume% or less is more preferable.
  • LiClO 4 LiPF 6, LiBF 4, LiAsF 6, LiSbF 6, LiCF 3 SO 3, LiC 4 F 9 SO 3, LiCF 3 CO 2, Li 2 C 2 F 4 ( SO 3 ) 2 , LiN (CF 3 SO 2 ) 2 , LiC (CF 3 SO 2 ) 3 , LiCnF 2n + 1 SO 3 (n ⁇ 2) are used alone or in combination.
  • LiPF 6 and LiC 4 F 9 SO 3 that can obtain good charge / discharge characteristics are preferably used.
  • the concentration of the electrolyte in the electrolytic solution is not particularly limited, but is preferably about 0.3 to 1.7 mol / dm 3 , particularly about 0.4 to 1.5 mol / dm 3 .
  • an aromatic compound may be contained in the nonaqueous electrolytic solution.
  • aromatic compound benzenes having an alkyl group such as cyclohexylbenzene or t-butylbenzene, biphenyl, or fluorobenzenes are preferably used.
  • the separator As the separator, a separator having sufficient strength and capable of holding a large amount of electrolyte is preferable. From this viewpoint, the separator is preferably 5 to 50 ⁇ m in thickness, and is preferably made of a microporous film or non-woven fabric made of polyolefin such as polypropylene, polyethylene, or a copolymer of propylene and ethylene.
  • the separator when a thin separator of 5 to 20 ⁇ m is used, the characteristics of the battery are likely to deteriorate during charge / discharge cycles and high-temperature storage, and the safety is also lowered.
  • the non-aqueous electrolyte secondary battery using the composite oxide as a positive electrode active material is excellent in stability and safety, the battery can function stably even if such a thin separator is used. it can.
  • the shape of the non-aqueous electrolyte secondary battery constituted by the above components can be various, such as a cylindrical shape, a stacked shape, and a coin shape.
  • a separator is sandwiched between the positive electrode and the negative electrode to form an electrode body.
  • the positive electrode current collector and the negative electrode current collector are connected to the positive electrode terminal and the negative electrode terminal that communicate with the outside with a current collecting lead or the like, and the electrode body is impregnated with the electrolyte solution and sealed in the battery case.
  • An electrolyte secondary battery is completed.
  • the non-aqueous electrolyte secondary battery using the composite oxide obtained by the production method of the present invention described above is suitably used in the field of automobiles in addition to the fields of communication devices such as mobile phones and personal computers, information-related devices. it can.
  • this non-aqueous electrolyte secondary battery is mounted on a vehicle, the non-aqueous electrolyte secondary battery can be used as a power source for an electric vehicle.
  • Example 1 a positive electrode active material mainly composed of LiNiO 2 was produced by the molten salt method as follows.
  • the raw material mixture was put in a crucible, transferred into an electric furnace at 700 ° C., and heated in the atmosphere at 700 ° C. for 2 hours. At this time, the raw material mixture melted to form a molten salt, and a black product was precipitated.
  • the crucible containing the molten salt was cooled to room temperature in the electric furnace and then taken out from the electric furnace. After the molten salt was sufficiently cooled and solidified, the entire crucible was immersed in 200 ml of ion exchange water and stirred to dissolve the solidified molten salt in water. Since the black product was insoluble in water, the water became a black suspension. Filtration of the black suspension gave a clear filtrate and a black solid filtrate on the filter paper. The obtained filtrate was further filtered while thoroughly washing with acetone. The black solid after washing was vacuum-dried at 120 ° C. for 12 hours and then pulverized using a mortar and pestle.
  • X-ray diffraction using CuK ⁇ rays as X-rays was measured for the obtained black powder.
  • the measurement result of X-ray diffraction is shown in FIG.
  • Comparative Example 1 a positive electrode active material containing LiNiO 2 as a main component was prepared by a solid phase method as follows.
  • the raw material mixture was thoroughly mixed in a mortar, then placed in a crucible and heated in an oxygen atmosphere (oxygen gas concentration 100%) at 1000 ° C. for 12 hours.
  • the obtained powder was pulverized using a mortar and pestle, put in a crucible, and further heated at 1000 ° C. for 12 hours in an oxygen atmosphere (oxygen gas concentration 100%).
  • X-ray diffraction using CuK ⁇ rays as X-rays was measured for the obtained black powder.
  • the measurement result of X-ray diffraction is shown in FIG.
  • Example 1 A lithium secondary battery was produced using the powder produced in Example 1 and Comparative Example 1 as the positive electrode active material, and the discharge capacity was measured.
  • Example 1 The composite oxide of any of Example 1 and Comparative Example 1, acetylene black as a conductive additive, and polytetrafluoroethylene (PTFE) as a binder are mixed at a mass ratio of 50:40:10. did. Subsequently, this mixture was crimped
  • PTFE polytetrafluoroethylene
  • a microporous polyethylene film having a thickness of 20 ⁇ m was sandwiched between the positive electrode and the negative electrode as a separator to obtain an electrode body battery.
  • This electrode body battery was accommodated in a battery case (CR2032 coin cell manufactured by Hosen Co., Ltd.).
  • a non-aqueous electrolyte in which LiPF 6 is dissolved at a concentration of 1.0 mol / L is injected into a mixed solvent in which ethylene carbonate and ethyl methyl carbonate are mixed at a volume ratio of 1: 2 into the battery case.
  • a secondary battery was obtained.
  • the prepared lithium secondary battery was subjected to a charge / discharge test at a constant temperature of 25 ° C.
  • charging was performed at a constant current up to 4.5 V at a rate of 0.2 C, and then charging was performed at a constant voltage of 4.5 V up to a current value of 0.02 C.
  • discharging was performed at a rate of 0.2 C up to 2.0V.
  • the charge / discharge curves for the secondary batteries produced using the positive electrode active materials of Example 1 and Comparative Example 1 are shown in FIG. In FIG.
  • the solid line shows the charge / discharge curve of the battery using the positive electrode active material of Example 1
  • the dotted line shows the charge / discharge curve of the battery using the positive electrode active material of Comparative Example 1.
  • the battery using the positive electrode active material containing NiO Example 1
  • had a higher discharge capacity than the battery using the positive electrode active material containing no NiO Comparative Example 1.
  • the reaction step was 2 hours shorter than the normal heating time.
  • the heating time is set longer than usual. Even in the solid phase method, it is estimated that NiO remains in the reaction system if the heating time is shortened.
  • Example 2 a positive electrode active material mainly composed of Li 2 MnO 3 .LiNi 1/3 Co 1/3 Mn 1/3 O 2 was prepared by the molten salt method as follows.
  • the raw material mixture was put in a crucible, transferred into an electric furnace at 700 ° C., and heated in the atmosphere at 700 ° C. for 2 hours. At this time, the raw material mixture melted to form a molten salt, and a black product was precipitated.
  • the crucible containing the molten salt was cooled to room temperature in the electric furnace and then taken out from the electric furnace. After the molten salt was sufficiently cooled and solidified, the crucible was immersed in 200 ml of ion exchange water, and the molten salt solidified by stirring was dissolved in water. Since the black product was insoluble in water, the water became a black suspension. Filtration of the black suspension gave a clear filtrate and a black solid filtrate on the filter paper. The obtained filtrate was further filtered while thoroughly washing with acetone. The black solid after washing was vacuum-dried at 120 ° C. for 12 hours and then pulverized using a mortar and pestle.
  • FIG. 3A shows the result of X-ray diffraction measurement.
  • XRD X-ray diffraction
  • Comparative Example 2 a positive electrode active material mainly composed of Li 2 MnO 3 .LiNi 1/3 Co 1/3 Mn 1/3 O 2 was produced by a solid phase method as follows.
  • a raw material mixture was prepared by mixing 0.10 mol of lithium hydroxide-hydrate LiOH.H 2 O as a lithium compound raw material and 0.10 mol of nickel manganese cobalt oxide as a nickel compound raw material. .
  • the raw material mixture was mixed well in a mortar, then placed in a crucible and heated at 1000 ° C. for 12 hours in an oxygen atmosphere (oxygen gas content 100%).
  • the obtained powder was pulverized using a mortar and pestle, placed in a crucible, and further heated at 1000 ° C. for 12 hours in an oxygen atmosphere (oxygen gas concentration 100%).
  • XRD X-ray diffraction
  • Example 2 Using the powders of Example 2 and Comparative Example 2 as the positive electrode active material, lithium secondary batteries were produced in the same manner as in Experiment 1, and the charge / discharge capacity was measured. The measurement results are shown in FIG. In FIG. 4, the solid line shows the charge / discharge curve of the battery using the positive electrode active material of Example 2, and the dotted line shows the charge / discharge curve of the battery using the positive electrode active material of Comparative Example 2. As shown in FIG. 4, the battery using the positive electrode active material containing NiO (Example 2) had a higher discharge capacity than the battery using the positive electrode active material containing no NiO (Comparative Example 2).

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Abstract

Provided are: a cathode active material that is for a non-aqueous electrolyte secondary battery having superior battery characteristics; a method for producing the cathode active material; a non-aqueous electrolyte secondary battery using the cathode active material; and a vehicle. The cathode active material for a non-aqueous electrolyte secondary battery has a nickel oxide and a lithium-nickel complex oxide having a crystal structure classified as a layered rock salt structure and containing at least the element lithium (Li) and the element nickel (Ni). The nickel oxide comprises a portion of the starting materials for producing the lithium-nickel complex oxide, or a byproduct generated by the starting materials.

Description

非水電解質二次電池用正極活物質及びその製造方法、並びにこれを用いた非水電解質二次電池Positive electrode active material for non-aqueous electrolyte secondary battery, method for producing the same, and non-aqueous electrolyte secondary battery using the same
　本発明は、非水電解質二次電池用正極活物質及びその製造方法、並びにこれを用いた非水電解質二次電池に関する。 The present invention relates to a positive electrode active material for a non-aqueous electrolyte secondary battery, a manufacturing method thereof, and a non-aqueous electrolyte secondary battery using the same.
　近年、携帯電話やノート型パソコンなどのポータブル電子機器の発達や、電気自動車の実用化などに伴い、小型で軽量でかつ高容量の二次電池が必要とされている。この要望に応える高容量二次電池として、正極活物質としてリチウム複合酸化物、負極活物質としては炭素系材料、Ｓｉ系、又はリチウム金属を用いた非水電解質二次電池が開発されている。 In recent years, along with the development of portable electronic devices such as mobile phones and notebook computers, and the practical application of electric vehicles, secondary batteries with small size, light weight and high capacity are required. As a high-capacity secondary battery that meets this demand, a non-aqueous electrolyte secondary battery using a lithium composite oxide as a positive electrode active material and a carbon-based material, Si-based, or lithium metal as a negative electrode active material has been developed.
　正極活物質として用いられるリチウム複合酸化物には、例えば、層状岩塩構造のリチウムコバルト複合酸化物（ＬｉＣｏＯ２）、層状岩塩構造のリチウムニッケル系複合酸化物（例えば、ＬｉＮｉＯ２）がよく知られている。 As the lithium composite oxide used as the positive electrode active material, for example, a layered rock salt structure lithium cobalt composite oxide (LiCoO 2 ) and a layered rock salt structure lithium nickel composite oxide (for example, LiNiO 2 ) are well known. Yes.
　この中、層状岩塩構造のリチウムコバルト複合酸化物を用いた二次電池は、エネルギー密度が高く、小型化及び軽量化が図れることから、幅広い分野で電源としての使用が注目されている。しかしながら、リチウムコバルト複合酸化物は、希少金属であるＣｏ（コバルト）を原料としていることから、今後、資源不足が懸念される。また、Ｃｏは、高価であり、価格変動も大きい。 Among them, secondary batteries using a layered rock salt structure lithium cobalt composite oxide have high energy density and can be reduced in size and weight. However, since lithium cobalt complex oxide uses Co (cobalt), which is a rare metal, as a raw material, there is a concern about resource shortage in the future. Co is expensive and has a large price fluctuation.
　一方、層状岩塩構造のリチウムニッケル系複合酸化物は、リチウムコバルト複合酸化物に比べて資源的に豊富であり安価である。このため、リチウムニッケル系複合酸化物を用いた正極活物質が開発されている。例えば、特開２００６－３０２８８０号公報に開示されているように、リチウムニッケル系複合酸化物からなる活物質粒子の表面に、ニッケル酸化物からなる表層部を形成する技術がある。 On the other hand, lithium nickel-based composite oxides with a layered rock salt structure are more abundant and less expensive than lithium cobalt composite oxides. For this reason, a positive electrode active material using a lithium nickel composite oxide has been developed. For example, as disclosed in Japanese Patent Application Laid-Open No. 2006-302880, there is a technique for forming a surface layer portion made of nickel oxide on the surface of active material particles made of lithium nickel composite oxide.
特開２００６－３０２８８０号公報JP 2006-302880 A
　しかしながら、特開２００６－３０２８８０号公報では、リチウムニッケル系複合酸化物からなる活物質粒子の表面が、反応に関与しないニッケル酸化物で被覆される。このため、電池反応が抑えられ、電池特性が低下する場合がある。 However, in Japanese Patent Application Laid-Open No. 2006-302880, the surface of active material particles made of lithium nickel composite oxide is coated with nickel oxide that does not participate in the reaction. For this reason, a battery reaction is suppressed and a battery characteristic may fall.
　また、J.Electrochem.Soc.,140,P.1862(1993)に記載されているように、層状岩塩構造のリチウムニッケル系複合酸化物は、岩塩ドメインと呼ばれる電気化学的に不活性な不規則配列岩塩層の領域をもつ。不規則配列岩塩層の領域をもつリチウムニッケル系複合酸化物では、高容量の電池を作製することは困難である。 In addition, as described in J. Electrochem. Soc., 140, P. 1862 (1993), the layered rock-salt lithium-nickel composite oxide is an electrochemically inert disorder called a rock salt domain. It has an area of an array rock salt layer. It is difficult to produce a high-capacity battery with a lithium nickel-based composite oxide having an irregularly arranged rock salt region.
　本願発明者は、層状岩塩構造のリチウムニッケル系複合酸化物について、電池容量を高くするために、種々の研究を重ねた。その結果、リチウムニッケル系複合酸化物の出発物質や加熱温度、条件などが、電池の性能に大きく影響することがわかった。 The inventor of the present application has made various studies on a lithium nickel-based composite oxide having a layered rock salt structure in order to increase the battery capacity. As a result, it was found that the starting material, heating temperature, conditions, and the like of the lithium nickel composite oxide greatly affect the battery performance.
　本発明はかかる事情に鑑みてなされたものであり、電池特性に優れた非水電解質二次電池用正極活物質及びその製造方法並びに非水電解質二次電池を提供することを課題とする。 The present invention has been made in view of such circumstances, and an object thereof is to provide a positive electrode active material for a non-aqueous electrolyte secondary battery excellent in battery characteristics, a method for producing the same, and a non-aqueous electrolyte secondary battery.
　（１）本発明の非水電解質二次電池用正極活物質は、少なくともリチウム（Ｌｉ）元素及びニッケル（Ｎｉ）元素を含み結晶構造が層状岩塩構造に属するリチウムニッケル系複合酸化物と、ニッケル酸化物とを有し、前記ニッケル酸化物は、前記リチウムニッケル系複合酸化物を製造する原料の一部又は該原料より生成した副生成物であることを特徴とする。 (1) A positive electrode active material for a non-aqueous electrolyte secondary battery according to the present invention includes a lithium-nickel composite oxide containing at least a lithium (Li) element and a nickel (Ni) element and having a crystal structure of a layered rock salt structure, and nickel oxidation The nickel oxide is part of a raw material for producing the lithium nickel composite oxide or a by-product generated from the raw material.
　上記正極活物質は、層状岩塩構造をもつリチウムニッケル系複合酸化物と、ニッケル酸化物とを有する。ニッケル酸化物は、リチウムニッケル系複合酸化物を製造する原料の一部又は該原料より生成した副生成物である。即ち、ニッケル酸化物は、リチウムニッケル系複合酸化物を生成する際に副生成物として生成する不純物である。リチウムニッケル系複合酸化物を製造する原料は、例えば、リチウム（Ｌｉ）元素を必須とする一種以上の金属元素を含むリチウム化合物原料と、ニッケル（Ｎｉ）元素を必須とする一種以上の金属元素を含むニッケル化合物原料とからなる。リチウムニッケル系複合酸化物を製造するに当たっては、リチウム化合物原料とニッケル化合物原料とを混合し加熱する。加熱の際に、リチウム元素を構成成分とする層状岩塩構造が形成される。高温で長時間加熱すると、層状岩塩構造のリチウムサイトにニッケルイオンが入り込み、所謂カチオンミキシングが生じる。ニッケルイオンがリチウムサイトに入り込むと、その領域は局所的に不規則配列岩塩相（岩塩ドメイン）となる。岩塩ドメインは、それ自体が電気化学的に不活性である。しかもリチウムサイトに混入したニッケルイオンがリチウムイオンの二次元的拡散を阻害する。このため、岩塩ドメインは、正極活物質としての機能を急激に低下させる。そこで、本発明では、ニッケルイオンが層状岩塩構造のリチウムサイトに拡散する前に、加熱を終了して、ニッケルイオンがリチウムサイトに混入する量を制限することとしている。すると、ニッケルイオンの混入の少ないリチウムニッケル系複合酸化物が生成される。　 The positive electrode active material has a lithium nickel composite oxide having a layered rock salt structure and nickel oxide. The nickel oxide is a part of a raw material for producing a lithium nickel composite oxide or a by-product generated from the raw material. That is, nickel oxide is an impurity generated as a by-product when a lithium nickel-based composite oxide is generated. The raw material for producing the lithium-nickel-based composite oxide includes, for example, a lithium compound raw material containing one or more metal elements essential for lithium (Li) element and one or more metal elements essential for nickel (Ni) element. It consists of nickel compound raw material containing. In producing a lithium nickel composite oxide, a lithium compound raw material and a nickel compound raw material are mixed and heated. During heating, a layered rock salt structure containing lithium as a constituent is formed. When heated at a high temperature for a long time, nickel ions enter the lithium site of the layered rock salt structure and so-called cation mixing occurs. When nickel ions enter the lithium site, the region becomes locally disordered salt facies (salt domain). The rock salt domain is itself electrochemically inert. Moreover, nickel ions mixed in the lithium site inhibit the two-dimensional diffusion of lithium ions. For this reason, a rock salt domain reduces the function as a positive electrode active material rapidly. Therefore, in the present invention, heating is terminated before nickel ions diffuse into the lithium sites having a layered rock salt structure, and the amount of nickel ions mixed into the lithium sites is limited. As a result, a lithium nickel composite oxide with little nickel ion mixing is generated. *
　このようにして生成した正極活物質は、ニッケル酸化物（ＮｉＯ）を不純物として含む。正極活物質は、電極反応を行うリチウムニッケル系複合酸化物を主成分とし、ニッケル酸化物を微量含む程度であれば、長時間加熱して得た正極活物質に比べて、優れた電池特性を発揮することができる。 The positive electrode active material thus produced contains nickel oxide (NiO) as an impurity. The positive electrode active material is composed mainly of a lithium nickel composite oxide that undergoes an electrode reaction, and if it contains only a small amount of nickel oxide, it has superior battery characteristics compared to a positive electrode active material obtained by heating for a long time. It can be demonstrated.
　（２）本発明の非水電解質二次電池用正極活物質の製造方法は、上記の非水電解質二次電池用正極活物質の製造方法であって、ニッケルを必須とする一種以上の金属元素を含む酸化物、水酸化物及び金属塩から選ばれる一種以上の金属化合物を含むニッケル化合物原料と、リチウムを必須とする一種以上の金属元素を含む酸化物、水酸化物及び金属塩から選ばれる一種以上の金属化合物を含むリチウム化合物原料とを加熱して、前記ニッケル化合物原料から生成したニッケル酸化物を残した状態で前記ニッケル化合物原料と前記リチウム化合物原料とを反応させて前記リチウムニッケル系複合酸化物を得る反応工程をもつことを特徴とする。 (2) The method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery according to the present invention is a method for producing the above-described positive electrode active material for a non-aqueous electrolyte secondary battery, which is one or more metal elements essentially containing nickel Selected from a nickel compound raw material containing one or more metal compounds selected from oxides, hydroxides and metal salts, and oxides, hydroxides and metal salts containing one or more metal elements essential for lithium A lithium compound raw material containing one or more metal compounds is heated to react the nickel compound raw material and the lithium compound raw material while leaving the nickel oxide generated from the nickel compound raw material, thereby the lithium nickel composite It has the reaction process of obtaining an oxide.
　リチウム化合物原料とニッケル化合物原料とを加熱して、ニッケル化合物原料から生成したニッケル酸化物を残した状態で、層状岩塩構造をもつリチウムニッケル系複合酸化物を生成させている。このため、ニッケル酸化物由来のニッケルイオンがリチウムニッケル系複合酸化物の層状岩塩構造の中に拡散するのを抑えることができる。以上より、本発明の製造方法によれば、電池特性に優れた正極活物質を得ることができる。 The lithium compound raw material and the nickel compound raw material are heated to produce a lithium nickel composite oxide having a layered rock salt structure while leaving the nickel oxide generated from the nickel compound raw material. For this reason, nickel ions derived from nickel oxide can be prevented from diffusing into the layered rock salt structure of the lithium nickel composite oxide. As mentioned above, according to the manufacturing method of this invention, the positive electrode active material excellent in the battery characteristic can be obtained.
　（３）本発明の非水電解質二次電池は、上述に記載の非水電解質二次電池用正極活物質を含む正極と、負極と、非水電解質と、を備えることを特徴とする。 (3) A non-aqueous electrolyte secondary battery of the present invention is characterized by including a positive electrode including the positive electrode active material for a non-aqueous electrolyte secondary battery described above, a negative electrode, and a non-aqueous electrolyte.
　（４）本発明の車両は、上記に記載の非水電解質二次電池を搭載したことを特徴とする。 (4) The vehicle of the present invention is characterized by mounting the nonaqueous electrolyte secondary battery described above.
　本発明のリチウムイオン電池は、上記の正極活物質を備えるため、電池特性に優れる。 Since the lithium ion battery of the present invention includes the positive electrode active material described above, the battery characteristics are excellent.
　本発明の非水電解質二次電池用正極活物質及びその製造方法並びに非水電解質二次電池によれば、リチウムニッケル系複合酸化物だけでなく不純物としてのニッケル酸化物が含まれているため、電池特性を高めることができる。本発明の車両によれば、上記の非水電解質二次電池を搭載しているため、高い出力を発揮できる。 According to the positive electrode active material for a non-aqueous electrolyte secondary battery of the present invention, a method for producing the same, and a non-aqueous electrolyte secondary battery, not only lithium nickel-based composite oxides but also nickel oxides as impurities are included. Battery characteristics can be improved. According to the vehicle of the present invention, since the nonaqueous electrolyte secondary battery is mounted, a high output can be exhibited.
実施例１及び比較例１の正極活物質のＸ線回折測定結果を示す図である。It is a figure which shows the X-ray-diffraction measurement result of the positive electrode active material of Example 1 and Comparative Example 1. 実施例１及び比較例１の正極活物質を用いた非水電解質二次電池の充放電特性を示すグラフである。4 is a graph showing charge / discharge characteristics of a non-aqueous electrolyte secondary battery using the positive electrode active material of Example 1 and Comparative Example 1. 実施例２及び比較例２の正極活物質のＸ線回折測定結果を示す図である。It is a figure which shows the X-ray-diffraction measurement result of the positive electrode active material of Example 2 and Comparative Example 2. 実施例２及び比較例２の正極活物質を用いた非水電解質二次電池の充放電特性を示すグラフである。It is a graph which shows the charging / discharging characteristic of the nonaqueous electrolyte secondary battery using the positive electrode active material of Example 2 and Comparative Example 2.
　（非水電解質二次電池用正極活物質）
　本発明の非水電解質二次電池用正極活物質は、リチウムニッケル系複合酸化物とニッケル酸化物とを有する。 (Positive electrode active material for non-aqueous electrolyte secondary battery)
The positive electrode active material for a non-aqueous electrolyte secondary battery of the present invention has a lithium nickel composite oxide and nickel oxide.
　リチウムニッケル系複合酸化物は、少なくともリチウム（Ｌｉ）元素及びニッケル（Ｎｉ）元素を含む。リチウムニッケル系複合酸化物の結晶構造は層状岩塩構造に属する。リチウムニッケル系複合酸化物は、組成式：ｘＬｉ２Ｍ１Ｏ３・（１―ｘ）ＬｉＮｉｙＭ２ １－ｙＯ２（０≦ｘ＜１、０＜ｙ≦１、Ｍ１は、４価のＭｎを必須とする１種以上の金属元素、Ｍ２は、金属元素、いずれの場合もＬｉはその一部が水素で置換されていてもよい。）で表される複合酸化物を基本組成とするとよい。 The lithium nickel composite oxide contains at least a lithium (Li) element and a nickel (Ni) element. The crystal structure of the lithium nickel composite oxide belongs to the layered rock salt structure. The lithium nickel-based composite oxide has a composition formula: xLi 2 M 1 O 3. (1-x) LiNi y M 2 1-y O 2 (0 ≦ x <1, 0 <y ≦ 1, M 1 is 4 1 or more types of metal elements in which valent Mn is essential, M 2 is a metal element, and Li in each case, a part of which may be substituted with hydrogen.) The composition is good.
　組成式：ｘＬｉ２Ｍ１Ｏ３・（１―ｘ）ＬｉＮｉｙＭ２ １－ｙＯ２で表される複合酸化物は、ＬｉＮｉｙＭ２ １－ｙＯ２であるか、又はＬｉ２Ｍ１Ｏ３とＬｉＮｉｙＭ２ １－ｙＯ２との固溶体（Ｌｉ２Ｍ１Ｏ３－ＬｉＮｉｙＭ２ １－ｙＯ２）である。Ｌｉ２Ｍ１Ｏ３－ＬｉＮｉｙＭ２ １－ｙＯ２の中のＬｉ２Ｍ１Ｏ３とＬｉＮｉｙＭ２ １－ｙＯ２とは、いずれも含んでいるとよく、その比率は問わない。ＬｉＮｉｙＭ２ １－ｙＯ２、及びＬｉ２Ｍ１Ｏ３－ＬｉＮｉｙＭ２ １－ｙＯ２は、いずれも層状岩塩構造（α―ＮａＦｅＯ２型）をもつ複合酸化物である。 The composite oxide represented by the composition formula: xLi 2 M 1 O 3. (1-x) LiNi y M 2 1-y O 2 is LiNi y M 2 1-y O 2 or Li 2 M It is a solid solution of 1 O 3 and LiNi y M 2 1-y O 2 (Li 2 M 1 O 3 —LiNi y M 2 1-y O 2 ). Li 2 M 1 O 3 -LiNi y M 2 1-y and O Li 2 M 1 O 3 in the 2 and LiNi y M 2 1-y O 2 may as containing any, the ratio is any Absent. LiNi y M 2 1-y O 2 and Li 2 M 1 O 3 —LiNi y M 2 1-y O 2 are both complex oxides having a layered rock salt structure (α-NaFeO 2 type).
　Ｌｉ２Ｍ１Ｏ３は電池容量が大きく、ＬｉＮｉｙＭ２ １－ｙＯ２は電池のサイクル特性に優れるといわれている。Ｌｉ２Ｍ１Ｏ３とＬｉＮｉｙＭ２ １－ｙＯ２との双方を含むＬｉ２Ｍ１Ｏ３－ＬｉＮｉｙＭ２ １－ｙＯ２は、電池容量が大きく、且つ電池のサイクル特性に優れている。 Li 2 M 1 O 3 has a large battery capacity, and LiNi y M 2 1-y O 2 is said to have excellent battery cycle characteristics. Li 2 M 1 O 3 and LiNi y M 2 1-y O Li 2 M 1 O 3 -LiNi y M 2 1-y O 2 containing both a 2 has a large battery capacity and cycle characteristics of the battery Are better.
　Ｌｉ２Ｍ１Ｏ３は、一般式Ｌｉ（Ｌｉ０．３３Ｍ１ ０．６７）Ｏ２と書き表すことが可能であり、ＬｉＮｉｙＭ２ １－ｙＯ２と同じ層状結晶構造に属するとされている。そのため、ｘＬｉ２Ｍ１Ｏ３・（１－ｘ）ＬｉＮｉｙＭ２ １－ｙＯ２は、Ｌｉ１．３３―ｘＮｉｙＭ１ ０．６７－ｚＭ２ ｘ＋ｚ―ｙＯ２（Ｍ１は、４価のＭｎを必須とする１種以上の金属元素、Ｍ２は金属元素、０≦ｘ＜０．３３、０＜ｙ≦１、０≦ｚ＜０．６７）と記載される場合がある。 Li 2 M 1 O 3 can be expressed as the general formula Li (Li 0.33 M 1 0.67 ) O 2 and is said to belong to the same layered crystal structure as LiNi y M 2 1-y O 2. ing. Therefore, xLi 2 M 1 O 3 · (1-x) LiNi y M 2 1-y O 2 is Li 1.33-x Ni y M 1 0.67-z M 2 x + zy O 2 (M 1 Is one or more metal elements in which tetravalent Mn is essential, M 2 is a metal element, and 0 ≦ x <0.33, 0 <y ≦ 1, 0 ≦ z <0.67) There is.
　Ｌｉ２Ｍ１Ｏ３の中のＭ１は、４価のＭｎを必須とする。Ｍ１のほとんどは４価のＭｎであるのが好ましいが、Ｍ１を構成する金属元素のうち８０％未満更には５０％未満が、Ｍｎ以外の他の金属元素で置換されていてもよい。Ｍ１を構成し得る、Ｍｎ以外の他の金属元素としては、例えば、電極材料とした場合の充放電可能な容量の観点から、Ｎｉ、Ａｌ、Ｃｏ、Ｆｅ、Ｍｇ、Ｔｉから選ばれるのが好ましい。 M 1 in the li 2 M 1 O 3 is an essential component tetravalent Mn. Most of M 1 is preferably tetravalent Mn, but less than 80% and even less than 50% of the metal elements constituting M 1 may be substituted with other metal elements other than Mn. The metal element other than Mn that can constitute M 1 is, for example, selected from Ni, Al, Co, Fe, Mg, and Ti from the viewpoint of chargeable / dischargeable capacity when an electrode material is used. preferable.
　なお、不可避的に生じるＬｉ、Ｎｉ、Ｍ１、Ｍ２又はＯの欠損により、上記組成式からわずかにずれた複合酸化物も含む。したがって、上記Ｍ１の平均酸化数は、４価から若干ずれてもよく、３．８～４．２価まで許容される。 Note that composite oxides slightly deviating from the above composition formula due to defects of Li, Ni, M 1 , M 2, or O that are inevitably generated are included. Therefore, the average oxidation number of M 1 may be slightly different from tetravalent, and is allowed to be 3.8 to 4.2.
　ＬｉＮｉｙＭ２ １－ｙＯ２の中のＭ２は、Ｎｉサイトの置換元素である。Ｍ２は、リチウムニッケル系複合酸化物の任意元素である。Ｍ２は、金属元素であり、例えば、Ａｌ、Ｍｎ、Ｃｏ、Ｆｅ、Ｍｇ、Ｔｉの少なくとも１種であることが好ましい。 M 2 in the LiNi y M 2 1-y O 2 is a substituting element of Ni site. M 2 is an optional element of the lithium nickel composite oxide. M 2 is a metal element, and is preferably at least one of Al, Mn, Co, Fe, Mg, and Ti, for example.
　ＮｉｙとＭ２ １－ｙとを合わせた平均酸化数は、３価となるとよい。Ｍ２が、３価の金属元素の場合には、Ｎｉの価数は３価となる。３価の元素としては、Ｃｏ、Ａｌ、Ｍｇ、Ｆｅ、Ｓｎがある。Ｍ２がＭｎの場合には、Ｍ２としてのＭｎの価数は４価となり、Ｎｉの価数は２価となって、Ｍ２としてのＭｎとＮｉとは同じモル数含まれる。 The average oxidation number combining Ni y and M 2 1-y is preferably trivalent. When M 2 is a trivalent metal element, the valence of Ni is trivalent. Trivalent elements include Co, Al, Mg, Fe, and Sn. When M 2 is Mn, the valence of Mn as M 2 is tetravalent, the valence of Ni is bivalent, and Mn and Ni as M 2 are included in the same number of moles.
　なお、不可避的に生じるＬｉ、Ｎｉ、Ｍ１、Ｍ２又はＯの欠損により、上記組成式からわずかにずれた複合酸化物も含む。したがって、上記ＮｉｘとＭ２ １－ｘとを合わせた平均酸化数は、３価から若干ずれてもよく、２．８～３．２価まで許容される。 Note that composite oxides slightly deviating from the above composition formula due to defects of Li, Ni, M 1 , M 2, or O that are inevitably generated are included. Therefore, the average oxidation number of Ni x and M 2 1-x combined may be slightly different from trivalent, and is allowed to be 2.8 to 3.2.
　Ｌｉ２Ｍ１Ｏ３及びＬｉＮｉｙＭ２ １－ｙＯ２に含まれるＬｉは、その一部が水素（Ｈ）で置換されていてもよい。例えば、Ｌｉは、原子比で６０％以下さらには４５％以下がＨに置換されていてもよい。 A part of Li contained in Li 2 M 1 O 3 and LiNi y M 2 1-y O 2 may be substituted with hydrogen (H). For example, in Li, 60% or less, further 45% or less in atomic ratio may be substituted with H.
　組成式ｘＬｉ２Ｍ１Ｏ３・（１―ｘ）ＬｉＮｉｙＭ２ １－ｙＯ２で表される複合酸化物を基本組成とし、層状岩塩構造をもつリチウムニッケル系複合酸化物としては、例えば、組成式のｘが１である場合には、Ｌｉ２Ｍ１Ｏ３となり、組成式のｘが０．５の場合には、Ｌｉ２Ｍ１Ｏ３・ＬｉＮｉｙＭ２ １－ｙＯ２となり、組成式のｘが０の場合には、ＬｉＮｉｙＭ２ １－ｙＯ２となる。 As a lithium nickel-based composite oxide having a basic composition of a composite oxide represented by a composition formula xLi 2 M 1 O 3. (1-x) LiNi y M 2 1-y O 2 and having a layered rock salt structure, for example, When x in the composition formula is 1, Li 2 M 1 O 3 and when x in the composition formula is 0.5, Li 2 M 1 O 3 .LiNi y M 2 1-y O 2 When x in the composition formula is 0, LiNi y M 2 1-y O 2 is obtained.
　Ｌｉ２Ｍ１Ｏ３としては、たとえば、Ｌｉ２ＭｎＯ３などを挙げることができ、ＬｉＮｉｙＭ２ １－ｙＯ２としては、例えば、ＬｉＮｉＯ２、ＬｉＮｉ１／３Ｍｎ１／３Ｃｏ１／３Ｏ２、ＬｉＮｉ１／２Ｍｎ１／２Ｏ２、ＬｉＮｉ１／２Ｃｏ１／２Ｏ２などを挙げることができる。Ｌｉ２Ｍ１Ｏ３・ＬｉＮｉｙＭ２ １－ｙＯ２としては、Ｌｉ２ＭｎＯ３・ＬｉＮｉＯ２、Ｌｉ２ＭｎＯ３・ＬｉＮｉ１／３Ｍｎ１／３Ｃｏ１／３Ｏ２、Ｌｉ２ＭｎＯ３・ＬｉＮｉ１／２Ｍｎ１／２Ｏ２、Ｌｉ２ＭｎＯ３・ＬｉＮｉ１／２Ｃｏ１／２Ｏ２などを挙げることができる。 Examples of Li 2 M 1 O 3 include Li 2 MnO 3. Examples of LiNi y M 2 1-y O 2 include LiNiO 2 , LiNi 1/3 Mn 1/3 Co 1 / such as 3 O 2, LiNi 1/2 Mn 1/2 O 2, LiNi 1/2 Co 1/2 O 2 can be cited. Li 2 M 1 O 3 .LiNi y M 2 1-y O 2 includes Li 2 MnO 3 .LiNiO 2 , Li 2 MnO 3 .LiNi 1/3 Mn 1/3 Co 1/3 O 2 , Li 2 MnO such as 3 · LiNi 1/2 Mn 1/2 O 2 , Li 2 MnO 3 · LiNi 1/2 Co 1/2 O 2 can be cited.
　上記に列挙した複合酸化物の構成元素であるＮｉ、Ｍｎ、Ｃｏの一部は、他の金属元素で置換されていてもよい。得られる複合酸化物全体としては、例示した酸化物を基本組成とすればよく、不可避的に生じる金属元素又は酸素の欠損により、上記組成式からわずかに外れていても良い。 A part of Ni, Mn, and Co, which are constituent elements of the composite oxide listed above, may be replaced with other metal elements. The obtained composite oxide as a whole may have the basic composition as the exemplified oxide, and may slightly deviate from the above composition formula due to unavoidable metal element or oxygen deficiency.
　正極活物質には、ニッケル酸化物（ＮｉＯ）が不純物として含まれている。ニッケル酸化物は、リチウムニッケル系複合酸化物の原料の一部又はその原料から生成した副生成物である。正極活物質の中のリチウムニッケル系複合酸化物を１００質量部としたときに、ニッケル酸化物は５質量部以上３０質量部以下含まれていることがよい。ニッケル酸化物が５質量部未満では、カチオンミキシングが進み、電気容量が低下するおそれがある。ニッケル酸化物が３０質量部を超える場合には、ニッケル酸化物は電池反応には関与しないため、電池容量が低下するおそれがある。 The positive electrode active material contains nickel oxide (NiO) as an impurity. The nickel oxide is a by-product generated from a part of the raw material of the lithium nickel composite oxide or the raw material. When the lithium nickel composite oxide in the positive electrode active material is 100 parts by mass, the nickel oxide is preferably contained in an amount of 5 parts by mass to 30 parts by mass. If the nickel oxide is less than 5 parts by mass, cation mixing proceeds and the electric capacity may be reduced. When the nickel oxide exceeds 30 parts by mass, the nickel oxide does not participate in the battery reaction, so that the battery capacity may be reduced.
　更には、正極活物質の中のリチウムニッケル系複合酸化物を１００質量部としたときに、ニッケル酸化物の含有量の下限は５質量部、望ましくは、１０質量部であり、上限は３０質量部、望ましくは１５質量部であることがよい。 Furthermore, when the lithium nickel composite oxide in the positive electrode active material is 100 parts by mass, the lower limit of the nickel oxide content is 5 parts by mass, preferably 10 parts by mass, and the upper limit is 30 parts by mass. Part, preferably 15 parts by weight.
　Ｘ線としてＣｕＫα線を用いた場合のＸ線回折図形におけるリチウムニッケル系複合酸化物の面指数（ｈ，ｋ，ｌ）＝（０，０，１）のピーク強度に対する、Ｘ線としてＣｕＫα線を用いた場合のＸ線回折図形における前記ニッケル酸化物の面指数（ｈ，ｋ，ｌ）＝（２，０，０）のピーク強度の比率は、０．１％以上２０％未満であることが好ましい。即ち、ＣｕＫα線を光源とするＸ線回折測定を行って作成された前記正極活物質のＸ線回折図形において、前記リチウムニッケル系複合酸化物の面指数（ｈ，ｋ，ｌ）＝（０，０，１）のピーク強度に対する、前記ニッケル酸化物の面指数（ｈ，ｋ，ｌ）＝（２，０，０）のピーク強度の比率は、０．１％以上２０％未満であることが好ましい。 When CuKα ray is used as the X-ray, the CuKα ray is used as the X-ray with respect to the peak intensity of the surface index (h, k, l) = (0, 0, 1) of the lithium nickel composite oxide in the X-ray diffraction pattern. The ratio of the peak intensity of the surface index (h, k, l) = (2, 0, 0) of the nickel oxide in the X-ray diffraction pattern when used is 0.1% or more and less than 20%. preferable. That is, in the X-ray diffraction pattern of the positive electrode active material prepared by performing X-ray diffraction measurement using CuKα rays as a light source, the surface index (h, k, l) of the lithium nickel-based composite oxide = (0, The ratio of the peak intensity of the nickel oxide plane index (h, k, l) = (2, 0, 0) to the peak intensity of (0, 1) may be 0.1% or more and less than 20%. preferable.
　ニッケル酸化物は、ＮｉＯを組成とし立方晶を形成している。Ｘ線回折の光源としてＣｕＫα線を用いた場合に、立方晶ＮｉＯのＸ線回折図形における面指数（ｈ，ｋ，ｌ）＝（２，０，０）のピーク位置は、２θ＝４３．３６３度近傍である。Ｘ線回折の光源としてＣｕＫα線を用いた場合に、リチウムニッケル系複合酸化物の多くのものについてのＸ線回折図形での面指数（ｈ，ｋ，ｌ）＝（０，０，１）のピーク強度は、２θ＝１８．６°近傍に位置する。 Nickel oxide has a composition of NiO and forms cubic crystals. When CuKα rays are used as a light source for X-ray diffraction, the peak position of the plane index (h, k, l) = (2, 0, 0) in the X-ray diffraction pattern of cubic NiO is 2θ = 43.363. Near the degree. When CuKα rays are used as the light source for X-ray diffraction, the surface index (h, k, l) = (0, 0, 1) in the X-ray diffraction pattern of many lithium nickel-based composite oxides The peak intensity is located in the vicinity of 2θ = 18.6 °.
　リチウムニッケル系複合酸化物と、ニッケル酸化物とは、それぞれ粒子を構成していることが好ましい。ニッケル酸化物は、反応目的物であるリチウムニッケル系複合酸化物に導入されなかった副生成物である。このため、ニッケル酸化物は、リチウムニッケル系複合酸化物とは別個の粒子として存在している。ニッケル酸化物は、電池反応に関与しない。このため、例えば、ニッケル酸化物でリチウムニッケル系複合酸化物表面を被覆すると、リチウムニッケル系複合酸化物の電池反応が妨げられるおそれがある。このため、本発明のように、ニッケル酸化物は、リチウムニッケル系複合酸化物とは別体の粒子を構成しているとよい。 It is preferable that the lithium nickel-based composite oxide and the nickel oxide each constitute particles. Nickel oxide is a by-product that has not been introduced into the lithium-nickel composite oxide that is the reaction target. For this reason, the nickel oxide exists as a particle separate from the lithium nickel composite oxide. Nickel oxide does not participate in the battery reaction. For this reason, for example, when the surface of the lithium nickel composite oxide is coated with nickel oxide, the battery reaction of the lithium nickel composite oxide may be hindered. Therefore, as in the present invention, the nickel oxide may constitute separate particles from the lithium nickel composite oxide.
　後述のリチウム化合物原料とニッケル化合物原料とを混合し加熱すると、層状岩塩構造をもつリチウムニッケル系複合酸化物の生成とともに、リチウムニッケル系複合酸化物の中のリチウムサイトの一部にニッケルが置換される。加熱時間が長くなるほど、ニッケルの置換度合いが大きくなる。 When a lithium compound raw material and a nickel compound raw material, which will be described later, are mixed and heated, nickel is substituted for part of the lithium sites in the lithium nickel composite oxide as well as the formation of a lithium nickel composite oxide having a layered rock salt structure. The The longer the heating time, the greater the degree of nickel replacement.
　ニッケルイオンが層状岩塩構造のリチウムサイトに混入すると、カチオンミキシングにより、ニッケルイオンがリチウムイオンの移動の妨げとなる。カチオンミキシングは、リチウムニッケル系複合酸化物の原料を長時間加熱すると生じる現象のため、カチオンミキシングが生じる前に、加熱を終了する。すると、リチウムイオンの出入りの障害となるニッケルイオンがリチウムサイトに入り込むことを抑制でき、電気出力の増加及び容量の増加となる。 When nickel ions are mixed into the lithium site of the layered rock salt structure, the nickel ions hinder the movement of lithium ions due to cation mixing. Cation mixing is a phenomenon that occurs when the raw material of the lithium nickel composite oxide is heated for a long time. Therefore, heating is terminated before cation mixing occurs. Then, it is possible to suppress nickel ions that become an obstacle to the entry / exit of lithium ions from entering the lithium site, resulting in an increase in electrical output and an increase in capacity.
　（非水電解質二次電池用正極活物質の製造方法）
　非水電解質二次電池用正極活物質を製造するにあたっては、リチウム化合物原料とニッケル化合物原料とを加熱して、前記ニッケル化合物原料から生成したニッケル酸化物を残した状態で前記リチウム化合物原料と前記ニッケル化合物原料とを反応させて前記リチウムニッケル系複合酸化物を得る反応工程を行う。この反応工程を行う前に、リチウム化合物原料とニッケル化合物原料とを混合して原料混合物を得る混合工程を行っても良い。 (Method for producing positive electrode active material for non-aqueous electrolyte secondary battery)
In producing a positive electrode active material for a nonaqueous electrolyte secondary battery, the lithium compound raw material and the nickel compound raw material are heated to leave the nickel oxide generated from the nickel compound raw material, A reaction step of obtaining a lithium nickel composite oxide by reacting with a nickel compound raw material is performed. Before performing this reaction process, you may perform the mixing process which mixes a lithium compound raw material and a nickel compound raw material, and obtains a raw material mixture.
　混合工程では、リチウム化合物原料とニッケル化合物原料とを混合して原料混合物を調製する。ニッケル化合物原料は、ニッケルを必須とする一種以上の金属元素を含む金属化合物を有するものであり、ニッケルを必須とする一種以上の金属元素を含む酸化物、水酸化物及び金属塩から選ばれる一種以上を有することが好ましい。 In the mixing step, a lithium compound raw material and a nickel compound raw material are mixed to prepare a raw material mixture. The nickel compound raw material has a metal compound containing one or more metal elements essential for nickel, and one kind selected from oxides, hydroxides and metal salts containing one or more metal elements essential for nickel It is preferable to have the above.
　リチウム化合物原料は、リチウムを必須とする一種以上の金属元素を含む金属化合物を有するものであり、リチウムを必須とする一種以上の金属元素を含む酸化物、水酸化物及び金属塩から選ばれる一種以上を有することが好ましい。金属塩としては、例えば、硝酸塩、硫酸塩、塩化物塩などがある。リチウム化合物原料は、主として水酸化リチウムを含むと良い。使用可能な水酸化リチウムとしては、ＬｉＯＨ、ＬｉＯＨ・Ｈ２Ｏなどが挙げられる。リチウム化合物原料には、リチウムの他に、リチウムニッケル系複合酸化物に含まれる金属元素を含んでいても良い。 The lithium compound raw material has a metal compound containing one or more metal elements essential for lithium, and one kind selected from oxides, hydroxides and metal salts containing one or more metal elements essential for lithium It is preferable to have the above. Examples of metal salts include nitrates, sulfates, chloride salts, and the like. The lithium compound raw material preferably contains mainly lithium hydroxide. Examples of lithium hydroxide that can be used include LiOH and LiOH.H 2 O. In addition to lithium, the lithium compound raw material may contain a metal element contained in the lithium nickel composite oxide.
　ニッケル化合物原料は、リチウムニッケル系複合酸化物に含まれるニッケルを、必須元素として含む。ニッケル化合物原料は、リチウム以外の金属元素を含んでもよい。正極活物質中のニッケル酸化物は、ニッケル化合物原料の一部又はニッケル化合物原料から生成した副生成物である。 The nickel compound raw material contains nickel contained in the lithium nickel composite oxide as an essential element. The nickel compound raw material may contain a metal element other than lithium. The nickel oxide in the positive electrode active material is a by-product generated from a part of the nickel compound raw material or the nickel compound raw material.
　ニッケル化合物原料は、このような金属元素を含む酸化物、水酸化物及び金属塩から選ばれる一種以上を有する。金属塩としては、例えば、硝酸塩、硫酸塩、塩化物塩などがある。 The nickel compound raw material has at least one selected from oxides, hydroxides and metal salts containing such metal elements. Examples of metal salts include nitrates, sulfates, chloride salts, and the like.
　ニッケル化合物原料は、水酸化ニッケル（ＮｉＯＨ）、硝酸ニッケル（Ｎｉ（ＮＯ３）２・６Ｈ２Ｏ）、硫酸ニッケル（Ｎｉ２ＳＯ４・６Ｈ２Ｏ））の少なくとも１種を含むとよい。 The nickel compound raw material may contain at least one of nickel hydroxide (NiOH), nickel nitrate (Ni (NO 3 ) 2 .6H 2 O), and nickel sulfate (Ni 2 SO 4 .6H 2 O).
　ニッケル化合物原料は、目的対象物の組成に４価のＭｎが含まれる場合には、更に、二酸化マンガン（ＭｎＯ２）、三酸化二マンガン（Ｍｎ２Ｏ３）、一酸化マンガン（ＭｎＯ）、四酸化三マンガン（Ｍｎ３Ｏ４）、水酸化マンガン（Ｍｎ（ＯＨ）２）、オキシ水酸化マンガン（ＭｎＯＯＨ）などを用いることができる。ニッケル化合物原料は、目的対象物の組成にＣｏが含まれる場合には、更に、酸化コバルト（ＣｏＯ、Ｃｏ３Ｏ４）、硝酸コバルト（Ｃｏ（ＮＯ３）２・６Ｈ２Ｏ）、水酸化コバルト（Ｃｏ（ＯＨ）２）などがある。ここで、ニッケル化合物原料の中のＭｎの価数は必ずしも４価である必要はない。４価以下のＭｎであってもよい。その理由は、例えば、溶融塩法で反応工程を行う場合、強酸化状態で反応が進むため、Ｍｎは２価又は３価であっても４価になるからである。ニッケル化合物原料の中のＮｉ、Ｃｏなどの金属元素についても、目的対象物の中の酸化数よりも低くてもよい。 In the case where tetravalent Mn is contained in the composition of the target object, the nickel compound raw material further includes manganese dioxide (MnO 2 ), dimanganese trioxide (Mn 2 O 3 ), manganese monoxide (MnO), tetra Trimanganese oxide (Mn 3 O 4 ), manganese hydroxide (Mn (OH) 2 ), manganese oxyhydroxide (MnOOH), or the like can be used. The nickel compound raw material further includes cobalt oxide (CoO, Co 3 O 4 ), cobalt nitrate (Co (NO 3 ) 2 · 6H 2 O), cobalt hydroxide when the composition of the target object contains Co. (Co (OH) 2 ). Here, the valence of Mn in the nickel compound raw material is not necessarily tetravalent. Tetravalent Mn or less may be used. The reason is that, for example, when the reaction step is performed by the molten salt method, the reaction proceeds in a strong oxidation state, so that Mn is tetravalent even if it is divalent or trivalent. The metal elements such as Ni and Co in the nickel compound raw material may also be lower than the oxidation number in the target object.
　また、ニッケル化合物原料が、二種以上の金属元素（Ｎｉを必須とする）を含む酸化物、水酸化物及び金属塩から選ばれる一種以上の金属化合物である場合には、これらを含む原料を前駆体としてあらかじめ合成するとよい。すなわち、混合工程の前に、少なくとも二種の金属元素を含む水溶液をアルカリ性にして沈殿物を得る前駆体合成工程を行うとよい。水溶液としては、水溶性の無機塩、具体的には金属元素の硝酸塩、硫酸塩、塩化物塩などを水に溶解し、アルカリ金属水酸化物、アンモニア水などで水溶液をアルカリ性にすると、前駆体は沈殿物として生成される。 Further, when the nickel compound raw material is one or more metal compounds selected from oxides, hydroxides and metal salts containing two or more metal elements (Ni is essential), the raw materials containing these are used. It may be synthesized in advance as a precursor. That is, before the mixing step, it is preferable to perform a precursor synthesis step in which an aqueous solution containing at least two kinds of metal elements is made alkaline to obtain a precipitate. As an aqueous solution, a water-soluble inorganic salt, specifically, a nitrate, sulfate, or chloride salt of a metal element is dissolved in water, and the aqueous solution is made alkaline with an alkali metal hydroxide, aqueous ammonia, etc. Is produced as a precipitate.
　上記リチウム化合物原料と上記ニッケル化合物原料を混合して、原料混合物を得る。 The lithium compound raw material and the nickel compound raw material are mixed to obtain a raw material mixture.
　上記混合工程の後であって、反応工程の前には、原料混合物を乾燥させる乾燥工程を行っても良い。ただし、ニッケル化合物原料として吸湿性の高い金属化合物を使用しない場合、又はリチウム化合物原料として水酸化リチウムの水和物を用いない場合、などには、乾燥工程を省略することも可能である。 After the above mixing step and before the reaction step, a drying step for drying the raw material mixture may be performed. However, when a highly hygroscopic metal compound is not used as the nickel compound raw material or when a lithium hydroxide hydrate is not used as the lithium compound raw material, the drying step can be omitted.
　反応工程では、上記のように調製した原料混合物を加熱して、ニッケル化合物原料から生成したニッケル酸化物を残した状態で原料混合物を反応させてリチウムニッケル系複合酸化物を得る。 In the reaction step, the raw material mixture prepared as described above is heated, and the raw material mixture is reacted in a state where the nickel oxide generated from the nickel compound raw material is left to obtain a lithium nickel composite oxide.
　反応工程での原料混合物の加熱は、原料混合物から目的対象物であるリチウムニッケル系複合酸化物が生成し、且つ生成したリチウムニッケル系複合酸化物の外部に、副生成物としてのニッケル酸化物が残る程度に留める。即ち、リチウムニッケル系複合酸化物の層状岩塩構造の中に、ニッケル化合物原料から生成したニッケル酸化物（ＮｉＯ）が導入される前か又は導入量が少ない程度で、原料混合物の加熱を止めて反応を終了させる。 The heating of the raw material mixture in the reaction step produces a target lithium nickel-based composite oxide from the raw material mixture, and nickel oxide as a by-product is formed outside the generated lithium nickel-based composite oxide. Keep it as it remains. That is, before the nickel oxide (NiO) produced from the nickel compound raw material is introduced into the layered rock salt structure of the lithium nickel-based composite oxide or the amount of introduction is small, the heating of the raw material mixture is stopped to react. End.
　反応工程での原料混合物の加熱は、例えば、固相法、スプレードライ法、水熱法、及び溶融塩法の中の少なくとも１種で行うことが好ましい。リチウムニッケル系複合酸化物の生成反応を通常の反応時間よりも短い時間で、副生成物としてニッケル酸化物（ＮｉＯ）を含むリチウムニッケル系複合酸化物を生成させることができるからである。この中、反応時間が比較的短いといった理由から、溶融塩法が望ましい。例えば、前記リチウム化合物原料と前記ニッケル化合物原料とを混合して原料混合物を調製する混合工程を行い、前記反応工程での前記原料混合物の加熱は、溶融塩法で行うとよい。 The heating of the raw material mixture in the reaction step is preferably performed by at least one of, for example, a solid phase method, a spray drying method, a hydrothermal method, and a molten salt method. This is because the lithium nickel composite oxide containing nickel oxide (NiO) as a by-product can be generated in a time shorter than the normal reaction time for the formation reaction of the lithium nickel composite oxide. Among these, the molten salt method is desirable because the reaction time is relatively short. For example, a mixing step of preparing a raw material mixture by mixing the lithium compound raw material and the nickel compound raw material is performed, and heating of the raw material mixture in the reaction step is preferably performed by a molten salt method.
　固相法は、原料粉末を混合・粉砕して、必要に応じて乾燥・圧粉成型して、加熱焼成することにより正極活物質を得る方法である。通常行われる固相法では、各原料が、製造しようとするリチウムニッケル系複合酸化物の組成に応じた割合で混合される。つまり、原料に含まれる各元素がリチウムニッケル系複合酸化物の化学量論組成となる割合で原料が混合される。 The solid phase method is a method of obtaining a positive electrode active material by mixing and pulverizing raw material powders, drying and compacting as necessary, and heating and firing. In the usual solid phase method, each raw material is mixed in a proportion corresponding to the composition of the lithium nickel composite oxide to be manufactured. That is, the raw materials are mixed in such a ratio that each element contained in the raw material has a stoichiometric composition of the lithium nickel composite oxide.
　固相法においては、原料混合物の加熱温度は、９００℃以上１０００℃以下であるとよい。また、原料混合物の加熱時間は８時間以上２４時間以下であることが好ましい。更には、加熱温度は、９２０℃以上９８０℃以下であって、加熱時間は１２時間以上１８時間以下であることが望ましい。加熱温度が９００℃未満の場合には、リチウムニッケル系複合酸化物の生成率が低くなるおそれがある。加熱温度が１０００℃を超える場合には、Ｌｉが揮発するおそれがある。加熱時間が８時間未満では、リチウムニッケル系複合酸化物の生成が不十分であり、加熱時間が２４時間を超える場合には、副生成物のニッケル酸化物由来のニッケルイオンがリチウムニッケル系複合酸化物の層状岩塩構造のリチウムサイトに導入され、カチオンミキシングを生じて、リチウムイオンの拡散が妨げられ、電池容量及び電池出力が低下するおそれがある。 In the solid phase method, the heating temperature of the raw material mixture is preferably 900 ° C. or higher and 1000 ° C. or lower. Moreover, it is preferable that the heating time of a raw material mixture is 8 hours or more and 24 hours or less. Furthermore, the heating temperature is preferably 920 ° C. or higher and 980 ° C. or lower, and the heating time is preferably 12 hours or longer and 18 hours or shorter. When the heating temperature is less than 900 ° C., the production rate of the lithium nickel composite oxide may be lowered. When heating temperature exceeds 1000 degreeC, there exists a possibility that Li may volatilize. When the heating time is less than 8 hours, the formation of the lithium nickel composite oxide is insufficient, and when the heating time exceeds 24 hours, the nickel oxide derived from the by-product nickel oxide is converted into the lithium nickel composite oxide. It is introduced into the lithium site of the layered rock salt structure of the object, causing cation mixing, and the diffusion of lithium ions is hindered, and the battery capacity and the battery output may be reduced.
　スプレードライ法は、原料粉末を液体に溶かして溶液とし、溶液を空中に噴霧しミストとし、ミストとした溶液を加熱する方法である。スプレードライ法では、後で更に加熱してもよい。 The spray drying method is a method in which a raw material powder is dissolved in a liquid to form a solution, the solution is sprayed into the air to form a mist, and the mist solution is heated. In the spray drying method, further heating may be performed later.
　スプレードライ法では、前記原料混合物の加熱温度は、５００℃以上１０００℃以下であるとよい。前記原料混合物の加熱時間は３時間以上８時間以下であることが好ましい。更には、加熱温度は、６００℃以上７００℃以下であって、加熱時間は５時間以上８時間以下であることが望ましい。加熱温度が５００℃未満の場合には、リチウムニッケル系複合酸化物の生成が不十分であるおそれがあり、１０００℃を超える場合にはＬｉが揮発するおそれがある。加熱時間が３時間未満では、リチウムニッケル系複合酸化物の生成が不十分であり、加熱時間が８時間を超える場合には、副生成物のニッケル酸化物由来のニッケルイオンがリチウムニッケル系複合酸化物のリチウムサイトに導入され、カチオンミキシングを生じて、リチウムイオンの出入りがしにくく、電池容量及び電池出力が低下するおそれがある。 In the spray drying method, the heating temperature of the raw material mixture is preferably 500 ° C. or higher and 1000 ° C. or lower. The heating time of the raw material mixture is preferably 3 hours or more and 8 hours or less. Furthermore, the heating temperature is preferably 600 ° C. or more and 700 ° C. or less, and the heating time is preferably 5 hours or more and 8 hours or less. When the heating temperature is less than 500 ° C., there is a possibility that the formation of the lithium nickel composite oxide is insufficient, and when it exceeds 1000 ° C., Li may volatilize. When the heating time is less than 3 hours, the formation of lithium nickel composite oxide is insufficient, and when the heating time exceeds 8 hours, nickel ions derived from the by-product nickel oxide are converted into lithium nickel composite oxide. Introduced into the lithium site of the product, cation mixing occurs, lithium ions do not easily enter and exit, and the battery capacity and battery output may be reduced.
　水熱法は、原料粉末を液体に溶かして溶液とし、溶液を高温高圧下で加熱する方法である。 The hydrothermal method is a method in which raw material powder is dissolved in a liquid to form a solution, and the solution is heated under high temperature and high pressure.
　水熱法での前記原料混合物の加熱温度は、１２０℃以上２００℃以下であって、加熱時間は２時間以上２４時間以下であることが好ましい。更には、加熱温度は、１５０℃以上１８０℃以下であって、加熱時間は４時間以上８時間以下であることが望ましい。加熱温度が１２０℃未満の場合には、Ｍｎの価数が大幅に低下するおそれがある。加熱時間が２時間未満では、リチウムニッケル系複合酸化物の生成が不十分であり、加熱時間が２４時間を超える場合には、副生成物のニッケル酸化物由来のニッケルイオンがリチウムニッケル系複合物のリチウムサイトに導入され、カチオンミキシングを生じて、リチウムイオンの出入りがしにくく、電池容量及び電池出力が低下するおそれがある。 The heating temperature of the raw material mixture in the hydrothermal method is preferably 120 ° C. or higher and 200 ° C. or lower, and the heating time is preferably 2 hours or longer and 24 hours or shorter. Furthermore, the heating temperature is preferably 150 ° C. or higher and 180 ° C. or lower, and the heating time is preferably 4 hours or longer and 8 hours or shorter. When the heating temperature is less than 120 ° C., the valence of Mn may be significantly reduced. When the heating time is less than 2 hours, the formation of the lithium nickel composite oxide is insufficient, and when the heating time exceeds 24 hours, the nickel oxide derived from the nickel oxide as a by-product becomes lithium nickel composite. When the lithium is introduced into the lithium site, cation mixing occurs, lithium ions do not easily enter and exit, and the battery capacity and battery output may be reduced.
　溶融塩法は、原料混合物を加熱することにより、リチウム化合物原料が溶融し溶融塩となり、この溶融液中でニッケル化合物原料を合成する方法である。溶融塩法では、リチウム化合物原料は、Ｌｉの供給源のみならず、溶融塩の酸化力を調整する役割を果たす。リチウム化合物原料に含まれるＬｉに対する、目的のリチウムニッケル系複合酸化物に含まれるＬｉの理論組成の比率（リチウムニッケル系複合酸化物のＬｉ／リチウム化合物原料のＬｉ）は、モル比で１未満であればよい。前記比率は、０．０２以上０．７未満であることが好ましく、更には０．０３～０．５、０．０４～０．２５であることが望ましい。前記比率が０．０２未満の場合には、原料であるリチウム化合物原料の量に対する、リチウムニッケル系複合酸化物の生成量が少なくなるため、製造効率の面で望ましくない。また、前記比率が０．７以上である場合には、ニッケル化合物原料を分散させるリチウム化合物原料（溶融塩）の量が不足し、すべての複合酸化物にＬｉを供給できなくなるため望ましくない。 The molten salt method is a method in which a raw material mixture is heated to melt a lithium compound raw material to form a molten salt, and a nickel compound raw material is synthesized in the melt. In the molten salt method, the lithium compound raw material plays a role in adjusting not only the Li supply source but also the oxidizing power of the molten salt. The ratio of the theoretical composition of Li contained in the target lithium nickel composite oxide (Li of lithium nickel composite oxide / Li of lithium compound raw material) to Li contained in the lithium compound raw material is less than 1 in molar ratio. I just need it. The ratio is preferably 0.02 or more and less than 0.7, more preferably 0.03 to 0.5, or 0.04 to 0.25. When the ratio is less than 0.02, the amount of lithium nickel-based composite oxide generated with respect to the amount of the raw material lithium compound raw material is reduced, which is not desirable in terms of production efficiency. On the other hand, when the ratio is 0.7 or more, the amount of the lithium compound raw material (molten salt) in which the nickel compound raw material is dispersed is insufficient, and Li cannot be supplied to all the composite oxides.
　溶融塩法でリチウムニッケル系複合酸化物を生成した後には、リチウムニッケル系複合酸化物を回収する回収工程を行うとよい。回収工程は、特に限定はないが、反応工程にて生成したリチウムニッケル系複合酸化物は水に不溶であるため、反応後の原料混合物を十分に冷却して凝固させて固体とし、固体を水に溶解することでリチウムニッケル系複合酸化物が不溶物として得られる。水溶液を濾過して得られた濾物を乾燥して、リチウムニッケル系複合酸化物を取り出せばよい。 After generating the lithium nickel composite oxide by the molten salt method, a recovery step of recovering the lithium nickel composite oxide may be performed. The recovery process is not particularly limited, but the lithium nickel composite oxide produced in the reaction process is insoluble in water. Therefore, the raw material mixture after the reaction is sufficiently cooled and solidified to form a solid. Lithium nickel-based composite oxide is obtained as an insoluble matter by dissolving in The filtrate obtained by filtering the aqueous solution may be dried to take out the lithium nickel composite oxide.
　また、回収工程は、反応工程後の原料混合物を徐冷してからリチウムニッケル系複合酸化物を回収する工程であるとよい。すなわち、反応工程の後には、リチウムニッケル系複合酸化物を徐冷してから回収する回収工程を行うとよい。反応終了後の高温の原料混合物を、加熱炉の中に放置して炉冷してもよいし、加熱炉から取り出して室温にて空冷してもよい。具体的には、反応工程後の原料混合物の温度が、４５０℃以下になる（つまり、反応後の原料混合物が凝固する）まで、２℃／分以上５０℃／分以下、さらには３～２５℃／分の速度で冷却することがよい。これにより、結晶性の高いリチウムニッケル系複合酸化物が得られ、特に、層状岩塩構造をもつリチウムニッケル系複合酸化物の合成に有利である。 Also, the recovery step may be a step of recovering the lithium nickel composite oxide after slowly cooling the raw material mixture after the reaction step. That is, after the reaction step, it is preferable to perform a recovery step in which the lithium nickel composite oxide is slowly cooled and recovered. The high-temperature raw material mixture after completion of the reaction may be left in a heating furnace and cooled, or may be taken out of the heating furnace and air-cooled at room temperature. Specifically, the temperature of the raw material mixture after the reaction step is 2 ° C./min to 50 ° C./min, further 3 to 25 until the temperature of the raw material mixture reaches 450 ° C. or lower (that is, the raw material mixture after the reaction solidifies). It is preferable to cool at a rate of ° C / min. Thereby, a lithium nickel composite oxide having high crystallinity can be obtained, which is particularly advantageous for the synthesis of a lithium nickel composite oxide having a layered rock salt structure.
　また、回収工程の後に、リチウムニッケル系複合酸化物のＬｉの一部を水素（Ｈ）に置換するプロトン置換工程を行ってもよい。プロトン置換工程では、回収工程後の複合酸化物を希釈した酸などの溶媒に接触させることで、Ｌｉの一部が容易にＨに置換する。 Further, after the recovery step, a proton substitution step of substituting part of Li of the lithium nickel composite oxide with hydrogen (H) may be performed. In the proton substitution step, a part of Li is easily substituted with H by bringing the composite oxide after the collection step into contact with a solvent such as diluted acid.
　また、回収工程（あるいはプロトン置換工程）の後に、リチウムニッケル系複合酸化物を酸素含有雰囲気中で加熱する加熱処理工程を行ってもよい。加熱処理工程は、酸素含有雰囲気、たとえば大気中、酸素ガスおよび／またはオゾンガスを含むガス雰囲気中で行うのがよい。酸素ガスを含有する雰囲気であれば、酸素ガス濃度を２０～１００体積％とするとよく、さらには５０～１００体積％とするのが好ましい。加熱温度は、３００℃以上とするとよく、さらには３５０～５００℃が望ましい。この加熱温度を２０分以上保持することが好ましく、さらには０．５～２時間保持するのが望ましい。 Further, after the recovery step (or proton substitution step), a heat treatment step of heating the lithium nickel composite oxide in an oxygen-containing atmosphere may be performed. The heat treatment step is preferably performed in an oxygen-containing atmosphere, for example, in the air, in a gas atmosphere containing oxygen gas and / or ozone gas. In an atmosphere containing oxygen gas, the oxygen gas concentration may be 20 to 100% by volume, and more preferably 50 to 100% by volume. The heating temperature is preferably 300 ° C. or higher, more preferably 350 to 500 ° C. This heating temperature is preferably maintained for 20 minutes or more, more preferably 0.5 to 2 hours.
　以上詳説した本発明の製造方法により得られた正極活物質に含まれるリチウムニッケル系複合酸化物は、粒子形状を呈している。リチウムニッケル系複合酸化物の一次粒子は、単結晶である。一次粒子が単結晶であることは、透過型電子顕微鏡（ＴＥＭ）の高分解能像により確認することができる。リチウムニッケル系複合酸化物の一次粒子のｃ軸方向の粒径は、２００ｎｍ以下であることがよく、さらには２０～１００ｎｍであることが好ましい。この粒径は、リチウムニッケル系複合酸化物の面指数（ｈ，ｋ，ｌ）＝（０，０，１）を示すピーク強度の半値幅に基づいて、シェラー（Ｓcherrer）の式を用いて算出されたものである。なお、半値幅は、リチウムニッケル系複合酸化物の面指数（ｈ，ｋ，ｌ）＝（０，０，１）を示すピークの強度をＩｍａｘとしたときに、Ｉｍａｘ／２の位置でのピークの幅とする。リチウムニッケル系複合酸化物の面指数（ｈ，ｋ，ｌ）＝（０，０，１）のピークは、回折角度（２θ、ＣｕＫα線）１８．６度付近に見られる。前述のように、一次粒子径が小さい方が活性化されやすいが、小さすぎると、充放電により結晶構造が崩れやすくなり、電池特性が低下することがあるため好ましくない。 The lithium nickel composite oxide contained in the positive electrode active material obtained by the production method of the present invention described in detail above has a particle shape. The primary particles of the lithium nickel composite oxide are single crystals. It can be confirmed by a high-resolution image of a transmission electron microscope (TEM) that the primary particles are single crystals. The particle size in the c-axis direction of the primary particles of the lithium nickel composite oxide is preferably 200 nm or less, and more preferably 20 to 100 nm. This particle size is calculated using the Scherrer equation based on the half-value width of the peak intensity indicating the plane index (h, k, l) = (0, 0, 1) of the lithium nickel composite oxide. It has been done. Incidentally, the half-value width, the plane index of the lithium nickel composite oxide (h, k, l) = intensity of a peak indicating the a (0,0,1) when the I max, in the position of I max / 2 The width of the peak. The peak of the plane index (h, k, l) = (0, 0, 1) of the lithium nickel-based composite oxide is seen in the vicinity of the diffraction angle (2θ, CuKα line) 18.6 degrees. As described above, the smaller primary particle size is likely to be activated. However, if the particle size is too small, the crystal structure is liable to collapse due to charge / discharge, and the battery characteristics may be deteriorated.
　本発明の製造方法により得られた正極活物質には、少量のニッケル酸化物（ＮｉＯ）が副生成物として含まれる。正極活物質中に含まれるニッケル酸化物の量は、Ｘ線回折（ＸＲＤ）などの分析で簡便に測定することができる。具体的には、光源Ｘ線としてＣｕＫα線を用いるＸ線回折法により正極活物質のＸ線回折図形を作成した場合、リチウムニッケル系複合酸化物の面指数（ｈ，ｋ，ｌ）＝（０，０，１）を示すピーク強度に対する、立方晶ＮｉＯの面指数（ｈ，ｋ，ｌ）＝（２，０，０）を示すピーク強度の比率が、０．１％以上２０％未満であることが好ましい。Ｘ線としてＣｕＫα線を用いた場合の立方晶ＮｉＯのＸ線回折図形での面指数（ｈ，ｋ，ｌ）＝（２，０，０）のピーク位置は２θ＝４３．３６３度であり、このことは、Ｘ線回折データベースであるＪＣＰＤＳカード（ＸＲＤの回折データ）に記録されており、J.Am.Chem.Soc.,V62, p1134(1940)の論文にも記載されている。 The positive electrode active material obtained by the production method of the present invention contains a small amount of nickel oxide (NiO) as a by-product. The amount of nickel oxide contained in the positive electrode active material can be easily measured by analysis such as X-ray diffraction (XRD). Specifically, when the X-ray diffraction pattern of the positive electrode active material is prepared by the X-ray diffraction method using CuKα rays as the light source X-ray, the surface index (h, k, l) of the lithium nickel composite oxide = (0 , 0, 1) to the peak intensity indicating cubic NiO, the ratio of the peak intensity indicating the plane index (h, k, l) = (2, 0, 0) is 0.1% or more and less than 20%. It is preferable. The peak position of the plane index (h, k, l) = (2, 0, 0) in the X-ray diffraction pattern of cubic NiO when CuKα ray is used as the X-ray is 2θ = 43.363 degrees, This is recorded in the JCPDS card (XRD diffraction data), which is an X-ray diffraction database, and is also described in a paper by J. Am. Chem. Soc., V62, p1134 (1940).
　（非水電解質二次電池）
　本発明の非水電解質二次電池用正極活物質を用いた非水電解質二次電池を説明する。非水電解質二次電池は、主として、正極、負極および非水電解質を備える。また、一般の非水電解質二次電池と同様に、正極と負極の間に挟装されるセパレータを備える。 (Non-aqueous electrolyte secondary battery)
A nonaqueous electrolyte secondary battery using the positive electrode active material for a nonaqueous electrolyte secondary battery of the present invention will be described. The nonaqueous electrolyte secondary battery mainly includes a positive electrode, a negative electrode, and a nonaqueous electrolyte. Moreover, the separator pinched | interposed between a positive electrode and a negative electrode is provided similarly to a general nonaqueous electrolyte secondary battery.
　正極は、リチウムイオンを挿入・脱離可能な正極活物質と、正極活物質を結着する結着剤と、を含む。さらに、導電助材を含んでもよい。正極活物質は、上記の複合酸化物を単独で用いても良い。または、正極活物質は、上記の複合酸化物とともに、一般の非水電解質二次電池に用いられるＬｉＣｏＯ２、ＬｉＭｎ２Ｏ４、Ｓなどのうちから選ばれる一種以上の他の正極活物質を含んでもよい。 The positive electrode includes a positive electrode active material capable of inserting / extracting lithium ions and a binder that binds the positive electrode active material. Further, a conductive aid may be included. As the positive electrode active material, the above complex oxide may be used alone. Alternatively, the positive electrode active material includes one or more other positive electrode active materials selected from LiCoO 2 , LiMn 2 O 4 , S, and the like used in general nonaqueous electrolyte secondary batteries, in addition to the above composite oxide. But you can.
　また、結着剤および導電助材にも特に限定はなく、一般の非水電解質二次電池で使用可能なものであればよい。導電助材は、電極の電気伝導性を確保するためのものであり、たとえば、カーボンブラック、アセチレンブラック、黒鉛などの炭素物質粉状体の１種または２種以上を混合したものを用いることができる。結着剤は、正極活物質および導電助材を繋ぎ止める役割を果たすものである。結着剤は、たとえば、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などを用いることができる。 Also, the binder and the conductive additive are not particularly limited as long as they can be used in a general non-aqueous electrolyte secondary battery. The conductive aid is for ensuring the electrical conductivity of the electrode, and for example, a mixture of one or more carbon material powders such as carbon black, acetylene black, and graphite may be used. it can. The binder plays a role of connecting the positive electrode active material and the conductive additive. Examples of the binder that can be used include fluorine-containing resins such as polyvinylidene fluoride, polytetrafluoroethylene, and fluororubber, and thermoplastic resins such as polypropylene and polyethylene.
　正極に対向させる負極は、負極活物質を有する。負極は、負極活物質である金属リチウムをシート状にして、あるいはシート状にしたものをニッケル、ステンレス等の集電体網に圧着して形成することができる。負極活物質として、金属リチウムのかわりに、リチウム合金またはリチウム化合物原料をも用いることができる。また、正極同様、リチウムイオンを吸蔵・脱離できる負極活物質と結着剤とからなる負極を使用してもよい。負極活物質としては、たとえば、天然黒鉛、人造黒鉛、フェノール樹脂等の有機化合物加熱体、コークス等の炭素物質の粉状体を用いることができる。また、負極活物質としては、負極活物質は、リチウムイオンを吸蔵・放出可能であってリチウムと合金化可能な元素又は／及びリチウムと合金化可能な元素を有する元素化合物からなるとよい。リチウムと合金化可能な元素は、Ｎａ、Ｋ、Ｒｂ、Ｃｓ、Ｆｒ、Ｂｅ、Ｍｇ、Ｃａ、Ｓｒ、Ｂａ、Ｒａ、Ｔｉ、Ａｇ、Ｚｎ、Ｃｄ、Ａｌ、Ｇａ、Ｉｎ、Ｓｉ、Ｇｅ、Ｓｎ、Ｐｂ、Ｓｂ、Ｂｉの少なくとも１種を有するとよい。結着剤としては、正極同様、含フッ素樹脂、熱可塑性樹脂などを用いることができる。負極活物質として金属リチウム又はリチウム合金を用いた二次電池は、リチウム二次電池といい、それ以外の負極活物質を用いた場合にはリチウムイオン二次電池という。 The negative electrode facing the positive electrode has a negative electrode active material. The negative electrode can be formed by forming a sheet of metal lithium, which is a negative electrode active material, or pressing the sheet into a current collector network such as nickel or stainless steel. As the negative electrode active material, a lithium alloy or a lithium compound raw material can be used instead of metallic lithium. Moreover, you may use the negative electrode which consists of a negative electrode active material and binder which can occlude / desorb lithium ion like a positive electrode. As the negative electrode active material, for example, a natural graphite, artificial graphite, an organic compound heating body such as a phenol resin, or a carbonaceous powder such as coke can be used. Moreover, as a negative electrode active material, a negative electrode active material is good to consist of an element compound which can occlude / release lithium ion and has an element which can be alloyed with lithium, and / or an element which can be alloyed with lithium. Elements that can be alloyed with lithium are Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, Ra, Ti, Ag, Zn, Cd, Al, Ga, In, Si, Ge, Sn. , Pb, Sb, Bi may be included. As the binder, as in the positive electrode, a fluorine-containing resin, a thermoplastic resin, or the like can be used. A secondary battery using metallic lithium or a lithium alloy as the negative electrode active material is referred to as a lithium secondary battery, and when a negative electrode active material other than that is used, it is referred to as a lithium ion secondary battery.
　一般的には、正極および負極は、正極活物質または負極活物質の各活物質が結着剤で結着された活物質層と、活物質層で被覆された集電体とからなる。そのため、正極および負極は、活物質および結着剤、必要に応じて導電助材を含む電極合材層形成用組成物を調製し、さらに適当な溶剤を加えてペースト状にしてから集電体の表面に塗布後、乾燥し、必要に応じて電極密度を高めるべく圧縮して形成することができる。 Generally, the positive electrode and the negative electrode are composed of an active material layer in which each of the positive electrode active material or the negative electrode active material is bound with a binder, and a current collector covered with the active material layer. Therefore, a positive electrode and a negative electrode are prepared by preparing an electrode mixture layer forming composition containing an active material, a binder, and, if necessary, a conductive additive, and further adding a suitable solvent to make a paste, After coating on the surface of the film, it can be dried and, if necessary, compressed to increase the electrode density.
　集電体は、金属製のメッシュや金属箔を用いることができる。具体的には、集電体としては、ステンレス鋼、チタン、ニッケル、アルミニウム、銅などの金属材料または導電性樹脂からなる多孔性または無孔の導電性基板が挙げられる。多孔性導電性基板としては、たとえば、メッシュ体、ネット体、パンチングシート、ラス体、多孔質体、発泡体、不織布などの繊維群成形体、などが挙げられる。無孔の導電性基板としては、たとえば、箔、シート、フィルムなどが挙げられる。電極合材層形成用組成物の塗布方法としては、ドクターブレード、バーコーターなどの従来から公知の方法を用いればよい。 The current collector can be a metal mesh or metal foil. Specifically, the current collector includes a porous or non-porous conductive substrate made of a metal material such as stainless steel, titanium, nickel, aluminum, copper, or a conductive resin. Examples of the porous conductive substrate include a mesh body, a net body, a punching sheet, a lath body, a porous body, a foamed body, a fiber group molded body such as a nonwoven fabric, and the like. Examples of the non-porous conductive substrate include a foil, a sheet, and a film. As a method for applying the composition for forming an electrode mixture layer, a conventionally known method such as a doctor blade or a bar coater may be used.
　粘度調整のための溶剤としては、Ｎ－メチル－２－ピロリドン（ＮＭＰ）、メタノール、メチルイソブチルケトン（ＭＩＢＫ）などが使用可能である。 As the solvent for adjusting the viscosity, N-methyl-2-pyrrolidone (NMP), methanol, methyl isobutyl ketone (MIBK) and the like can be used.
　電解質としては、有機溶媒に電解質を溶解させた有機溶媒系の電解液、電解液をポリマー中に保持させたポリマー電解質などを用いることができる。電解液あるいはポリマー電解質に含まれる有機溶媒は特に限定されるものではないが、負荷特性の点からは鎖状エステルを含んでいることが好ましい。そのような鎖状エステルとしては、たとえば、ジメチルカーボネート、ジエチルカーボネート、エチルメチルカーボネートに代表される鎖状のカーボネートや、酢酸エチル、プロピロン酸メチルなどの有機溶媒が挙げられる。これらの鎖状エステルは、単独でもあるいは２種以上を混合して用いてもよく、特に、低温特性の改善のためには、上記鎖状エステルが全有機溶媒中の５０体積％以上を占めることが好ましく、特に鎖状エステルが全有機溶媒中の６５体積％以上を占めることが好ましい。 As the electrolyte, an organic solvent-based electrolytic solution in which an electrolyte is dissolved in an organic solvent, a polymer electrolyte in which the electrolytic solution is held in a polymer, or the like can be used. The organic solvent contained in the electrolytic solution or polymer electrolyte is not particularly limited, but it preferably contains a chain ester from the viewpoint of load characteristics. Examples of such chain esters include chain carbonates typified by dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate, and organic solvents such as ethyl acetate and methyl propionate. These chain esters may be used alone or in admixture of two or more. Particularly, for improving low-temperature characteristics, the above-mentioned chain esters occupy 50% by volume or more in the total organic solvent. In particular, it is preferable that the chain ester occupies 65% by volume or more of the total organic solvent.
　有機溶媒としては、上記鎖状エステルのみで構成するよりも、放電容量の向上をはかるために、上記鎖状エステルに誘導率の高い（誘導率：３０以上）エステルを混合して用いることが好ましい。このようなエステルの具体例としては、たとえば、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に代表される環状のカーボネートや、γ－ブチロラクトン、エチレングリコールサルファイトなどが挙げられ、特にエチレンカーボネート、プロピレンカーボネートなどの環状構造のエステルが好ましい。そのような誘電率の高いエステルは、放電容量の点から、全有機溶媒中１０体積％以上、特に２０体積％以上含有されることが好ましい。また、負荷特性の点からは、４０体積％以下が好ましく、３０体積％以下がより好ましい。 As the organic solvent, it is preferable to use a mixture having a high induction rate (induction rate: 30 or more) ester in the chain ester, in order to improve the discharge capacity, rather than using only the chain ester. . Specific examples of such esters include cyclic carbonates typified by ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, γ-butyrolactone, ethylene glycol sulfite, and the like. A cyclic ester such as carbonate is preferred. Such an ester having a high dielectric constant is preferably contained in an amount of 10% by volume or more, particularly 20% by volume or more in the total organic solvent from the viewpoint of discharge capacity. Moreover, from the point of load characteristics, 40 volume% or less is preferable and 30 volume% or less is more preferable.
　有機溶媒に溶解させる電解質としては、たとえば、ＬｉＣｌＯ４、ＬｉＰＦ６、ＬｉＢＦ４、ＬｉＡｓＦ６、ＬｉＳｂＦ６、ＬｉＣＦ３ＳＯ３、ＬｉＣ４Ｆ９ＳＯ３、ＬｉＣＦ３ＣＯ２、Ｌｉ２Ｃ２Ｆ４（ＳＯ３）２、ＬｉＮ（ＣＦ３ＳＯ２）２、ＬｉＣ（ＣＦ３ＳＯ２）３、ＬｉＣnＦ２ｎ＋１ＳＯ３（ｎ≧２）などが単独でまたは２種以上混合して用いられる。中でも、良好な充放電特性が得られるＬｉＰＦ６やＬｉＣ４Ｆ９ＳＯ３などが好ましく用いられる。 As an electrolyte to be dissolved in an organic solvent, for example, LiClO 4, LiPF 6, LiBF 4, LiAsF 6, LiSbF 6, LiCF 3 SO 3, LiC 4 F 9 SO 3, LiCF 3 CO 2, Li 2 C 2 F 4 ( SO 3 ) 2 , LiN (CF 3 SO 2 ) 2 , LiC (CF 3 SO 2 ) 3 , LiCnF 2n + 1 SO 3 (n ≧ 2) are used alone or in combination. Among these, LiPF 6 and LiC 4 F 9 SO 3 that can obtain good charge / discharge characteristics are preferably used.
　電解液中における電解質の濃度は、特に限定されるものではないが、０．３～１．７ｍｏｌ／ｄｍ３、特に０．４～１．５ｍｏｌ／ｄｍ３程度が好ましい。 The concentration of the electrolyte in the electrolytic solution is not particularly limited, but is preferably about 0.3 to 1.7 mol / dm 3 , particularly about 0.4 to 1.5 mol / dm 3 .
　また、電池の安全性や貯蔵特性を向上させるために、非水電解液に芳香族化合物を含有させてもよい。芳香族化合物としては、シクロヘキシルベンゼンやｔ－ブチルベンゼンなどのアルキル基を有するベンゼン類、ビフェニル、あるいはフルオロベンゼン類が好ましく用いられる。 Moreover, in order to improve the safety and storage characteristics of the battery, an aromatic compound may be contained in the nonaqueous electrolytic solution. As the aromatic compound, benzenes having an alkyl group such as cyclohexylbenzene or t-butylbenzene, biphenyl, or fluorobenzenes are preferably used.
　セパレータとしては、強度が充分でしかも電解液を多く保持できるものがよい。この観点から、セパレータは、５～５０μｍの厚さで、ポリプロピレン製、ポリエチレン製、プロピレンとエチレンとの共重合体などの、ポリオレフィン製の微孔性フィルムや不織布などが好ましく用いられる。特に、５～２０μｍと薄いセパレータを用いた場合には、充放電サイクルや高温貯蔵などにおいて電池の特性が劣化しやすく、安全性も低下する。しかし、上記の複合酸化物を正極活物質として用いた非水電解質二次電池は安定性と安全性に優れているため、このような薄いセパレータを用いても安定して電池を機能させることができる。 As the separator, a separator having sufficient strength and capable of holding a large amount of electrolyte is preferable. From this viewpoint, the separator is preferably 5 to 50 μm in thickness, and is preferably made of a microporous film or non-woven fabric made of polyolefin such as polypropylene, polyethylene, or a copolymer of propylene and ethylene. In particular, when a thin separator of 5 to 20 μm is used, the characteristics of the battery are likely to deteriorate during charge / discharge cycles and high-temperature storage, and the safety is also lowered. However, since the non-aqueous electrolyte secondary battery using the composite oxide as a positive electrode active material is excellent in stability and safety, the battery can function stably even if such a thin separator is used. it can.
　以上の構成要素によって構成される非水電解質二次電池の形状は円筒型、積層型、コイン型等、種々のものとすることができる。いずれの形状を採る場合であっても、正極と負極との間にセパレータを挟装させ電極体とする。そして正極集電体および負極集電体から外部に通ずる正極端子および負極端子までの間を集電用リードなどで接続し、この電極体に上記電解液を含浸させ電池ケースに密閉し、非水電解質二次電池が完成する。 The shape of the non-aqueous electrolyte secondary battery constituted by the above components can be various, such as a cylindrical shape, a stacked shape, and a coin shape. In any case, a separator is sandwiched between the positive electrode and the negative electrode to form an electrode body. Then, the positive electrode current collector and the negative electrode current collector are connected to the positive electrode terminal and the negative electrode terminal that communicate with the outside with a current collecting lead or the like, and the electrode body is impregnated with the electrolyte solution and sealed in the battery case. An electrolyte secondary battery is completed.
　非水電解質二次電池を使用する場合には、初期に充電を行い、正極活物質を活性化させる。ただし、上記の複合酸化物を正極活物質として用いる場合には、初回の充電時にリチウムイオンが放出されるとともに酸素が発生する。そのため、電池ケースを密閉する前に充電を行うのが望ましい。 When using a non-aqueous electrolyte secondary battery, it is charged in the initial stage to activate the positive electrode active material. However, when the composite oxide is used as a positive electrode active material, lithium ions are released and oxygen is generated during the first charge. For this reason, it is desirable to charge the battery case before sealing it.
  ＜車両など＞
　以上説明した本発明の製造方法により得られる複合酸化物を用いた非水電解質二次電池は、携帯電話、パソコン等の通信機器、情報関連機器の分野の他、自動車の分野においても好適に利用できる。たとえば、この非水電解質二次電池を車両に搭載すれば、非水電解質二次電池を電気自動車用の電源として使用できる。 <Vehicle etc.>
The non-aqueous electrolyte secondary battery using the composite oxide obtained by the production method of the present invention described above is suitably used in the field of automobiles in addition to the fields of communication devices such as mobile phones and personal computers, information-related devices. it can. For example, if this non-aqueous electrolyte secondary battery is mounted on a vehicle, the non-aqueous electrolyte secondary battery can be used as a power source for an electric vehicle.
 　以下、本発明の実施例を比較例と比較して説明する。
　（実施例１）
　本実施例では、以下のように、溶融塩法でＬｉＮｉＯ２を主成分とする正極活物質を作製した。 Hereinafter, examples of the present invention will be described in comparison with comparative examples.
Example 1
In this example, a positive electrode active material mainly composed of LiNiO 2 was produced by the molten salt method as follows.
　混合工程において、リチウム化合物原料（溶融塩原料）として０．２０ｍｏｌの水酸化リチウム－水和物ＬｉＯＨ・Ｈ２Ｏ（８．４ｇ）と、ニッケル化合物原料として０．０２ｍｏｌの水酸化ニッケルＮｉＯＨ（１．５１ｇ）とを混合して、原料混合物を調製した。 In the mixing step, 0.20 mol of lithium hydroxide-hydrate LiOH.H 2 O (8.4 g) as a lithium compound raw material (molten salt raw material) and 0.02 mol of nickel hydroxide NiOH (1 g) as a nickel compound raw material .51 g) was mixed to prepare a raw material mixture.
　反応工程において、原料混合物を坩堝に入れて、７００℃の電気炉内に移し、大気中７００℃で２時間加熱した。このとき原料混合物は、融解して溶融塩となり、黒色の生成物が沈殿した。 In the reaction process, the raw material mixture was put in a crucible, transferred into an electric furnace at 700 ° C., and heated in the atmosphere at 700 ° C. for 2 hours. At this time, the raw material mixture melted to form a molten salt, and a black product was precipitated.
　回収工程において、溶融塩の入った坩堝を電気炉内で室温まで冷却した後、電気炉から取り出した。溶融塩が十分に冷却されて固化した後、坩堝ごと２００ｍｌのイオン交換水に浸し、攪拌することで、固化した溶融塩を水に溶解した。黒色の生成物は水に対して不溶性であるため、水は黒色の懸濁液となった。黒色の懸濁液を濾過すると、透明な濾液と、濾紙上に黒色の固体の濾物とが得られた。得られた濾物を更にアセトンを用いて十分に洗浄しながら濾過した。洗浄後の黒色の固体を１２０℃で１２時間、真空乾燥した後、乳鉢と乳棒を用いて粉砕した。 In the recovery process, the crucible containing the molten salt was cooled to room temperature in the electric furnace and then taken out from the electric furnace. After the molten salt was sufficiently cooled and solidified, the entire crucible was immersed in 200 ml of ion exchange water and stirred to dissolve the solidified molten salt in water. Since the black product was insoluble in water, the water became a black suspension. Filtration of the black suspension gave a clear filtrate and a black solid filtrate on the filter paper. The obtained filtrate was further filtered while thoroughly washing with acetone. The black solid after washing was vacuum-dried at 120 ° C. for 12 hours and then pulverized using a mortar and pestle.
　得られた黒色粉末についてＸ線としてＣｕＫα線を用いたＸ線回折（ＸＲＤ）を測定した。Ｘ線回折の測定結果を図１（ａ）に示す。図１（ａ）に示すように、２θ＝１８．７９°にピークがあることから、黒色粉末は層状岩塩構造のＬｉＮｉＯ２を有することがわかる。また、２θ＝４３．３６３°などにＮｉＯに起因するピークが出現していることから、黒色粉末には、ＮｉＯが含まれていることがわかる。ＬｉＮｉＯ２の面指数（ｈ，ｋ，ｌ）＝（０，０，１）に起因するピーク（２θ＝１８．７９°）の強度に対する、ＮｉＯの面指数（ｈ，ｋ，ｌ）＝（２，０，０）に起因するピーク（２θ＝４３．３６３°）の強度の比率は、約２０％であった。このことから、ＬｉＮｉＯ２を１００質量部としたときのＮｉＯの含有量は１５.３質量部であることがわかる。 X-ray diffraction (XRD) using CuKα rays as X-rays was measured for the obtained black powder. The measurement result of X-ray diffraction is shown in FIG. As shown in FIG. 1 (a), the peak at 2θ = 18.79 ° indicates that the black powder has a layered rock salt structure of LiNiO 2 . Further, since a peak due to NiO appears at 2θ = 43.363 ° or the like, it can be seen that the black powder contains NiO. The surface index (h, k, l) of NiO with respect to the intensity of the peak (2θ = 18.79 °) due to the surface index (h, k, l) = (0, 0, 1) of LiNiO 2 = (2 , 0, 0), the ratio of the intensity of the peak (2θ = 43.363 °) was about 20%. This shows that the content of NiO is 15.3 parts by mass when LiNiO 2 is 100 parts by mass.
　（比較例１）
　本比較例では、以下のように、固相法でＬｉＮｉＯ２を主成分とする正極活物質を作製した。 (Comparative Example 1)
In this comparative example, a positive electrode active material containing LiNiO 2 as a main component was prepared by a solid phase method as follows.
　混合工程において、リチウム化合物原料として０．１１ｍｏｌの水酸化リチウム－水和物ＬｉＯＨ・Ｈ２Ｏ（２．６４ｇ）と、ニッケル化合物原料として０．１ｍｏｌの水酸化ニッケルＮｉＯＨ（７．５７ｇ）とを混合して、原料混合物を調製した。 In the mixing step, 0.11 mol of lithium hydroxide-hydrate LiOH.H 2 O (2.64 g) as a lithium compound raw material and 0.1 mol of nickel hydroxide NiOH (7.57 g) as a nickel compound raw material. The raw material mixture was prepared by mixing.
　反応工程において、原料混合物を乳鉢でよく混合した後、坩堝に入れて、酸素雰囲気（酸素ガス濃度１００％）中１０００℃で１２時間加熱した。得られた粉末を、乳鉢と乳棒を用いて粉砕した後、坩堝に入れて、さらに酸素雰囲気（酸素ガス濃度１００％）中、１０００℃で１２時間加熱した。 In the reaction step, the raw material mixture was thoroughly mixed in a mortar, then placed in a crucible and heated in an oxygen atmosphere (oxygen gas concentration 100%) at 1000 ° C. for 12 hours. The obtained powder was pulverized using a mortar and pestle, put in a crucible, and further heated at 1000 ° C. for 12 hours in an oxygen atmosphere (oxygen gas concentration 100%).
　得られた黒色粉末についてＸ線としてＣｕＫα線を用いたＸ線回折（ＸＲＤ）を測定した。Ｘ線回折の測定結果を図１（ｂ）に示す。図１（ｂ）に示すように、ＬｉＮｉＯ２の面指数（ｈ，ｋ，ｌ）＝（０，０，１）のピークが確認されたが、ＮｉＯの面指数（ｈ，ｋ，ｌ）＝（２，０，０）のピークは確認されなかった。 X-ray diffraction (XRD) using CuKα rays as X-rays was measured for the obtained black powder. The measurement result of X-ray diffraction is shown in FIG. As shown in FIG. 1B, the peak of the surface index (h, k, l) = (0, 0, 1) of LiNiO 2 was confirmed, but the surface index (h, k, l) of NiO = The peak of (2, 0, 0) was not confirmed.
　＜実験１＞
　実施例１及び比較例１で生成した粉末を正極活物質として用いてリチウム二次電池を作製し、放電容量を測定した。 <Experiment 1>
A lithium secondary battery was produced using the powder produced in Example 1 and Comparative Example 1 as the positive electrode active material, and the discharge capacity was measured.
　実施例１及び比較例１のいずれかの複合酸化物、導電助剤としてのアセチレンブラック、及び結着材としてのポリテトラフルオロエチレン（ＰＴＦＥ）を、質量比で５０：４０：１０の割合で混合した。次いで、この混合物を集電体であるアルミニウムメッシュに圧着した。その後、１２０℃で１２時間以上真空乾燥し、電極（正極：φ１４ｍｍ）とした。正極に対向させる負極は、金属リチウム（φ１４ｍｍ、厚さ４００μｍ）とした。 The composite oxide of any of Example 1 and Comparative Example 1, acetylene black as a conductive additive, and polytetrafluoroethylene (PTFE) as a binder are mixed at a mass ratio of 50:40:10. did. Subsequently, this mixture was crimped | bonded to the aluminum mesh which is a collector. Then, it vacuum-dried at 120 degreeC for 12 hours or more, and was set as the electrode (positive electrode: (phi) 14mm). The negative electrode facing the positive electrode was metallic lithium (φ14 mm, thickness 400 μm).
　正極および負極の間にセパレータとして厚さ２０μｍの微孔性ポリエチレンフィルムを挟装して電極体電池とした。この電極体電池を電池ケース（宝泉株式会社製ＣＲ２０３２コインセル）に収容した。また、電池ケースには、エチレンカーボネートとエチルメチルカーボネートとを１：２（体積比）で混合した混合溶媒にＬｉＰＦ６を１．０ｍｏｌ／Ｌの濃度で溶解した非水電解質を注入して、リチウム二次電池を得た。 A microporous polyethylene film having a thickness of 20 μm was sandwiched between the positive electrode and the negative electrode as a separator to obtain an electrode body battery. This electrode body battery was accommodated in a battery case (CR2032 coin cell manufactured by Hosen Co., Ltd.). In addition, a non-aqueous electrolyte in which LiPF 6 is dissolved at a concentration of 1.0 mol / L is injected into a mixed solvent in which ethylene carbonate and ethyl methyl carbonate are mixed at a volume ratio of 1: 2 into the battery case. A secondary battery was obtained.
　作製したリチウム二次電池について、２５℃一定温度下で充放電試験を行った。充放電試験で充電を行う場合には、０．２Ｃのレートで４．５Ｖまで定電流で充電を行い、その後０．０２Ｃの電流値まで４．５Ｖ一定電圧で充電を行った。放電を行う場合には、２．０Ｖまで０．２Ｃのレートで放電を行った。実施例１及び比較例１の正極活物質を用いて作製した二次電池についての充放電曲線を図２にそれぞれ示した。図２において、実線は実施例１の正極活物質を用いた電池の充放電曲線を示し、点線は比較例１の正極活物質を用いた電池の充放電曲線を示す。図２に示すように、ＮｉＯを含む正極活物質（実施例１）を用いた電池の方が、ＮｉＯを含まない正極活物質（比較例１）を用いた電池よりも放電容量が高かった。 The prepared lithium secondary battery was subjected to a charge / discharge test at a constant temperature of 25 ° C. When charging in the charge / discharge test, charging was performed at a constant current up to 4.5 V at a rate of 0.2 C, and then charging was performed at a constant voltage of 4.5 V up to a current value of 0.02 C. In the case of discharging, discharging was performed at a rate of 0.2 C up to 2.0V. The charge / discharge curves for the secondary batteries produced using the positive electrode active materials of Example 1 and Comparative Example 1 are shown in FIG. In FIG. 2, the solid line shows the charge / discharge curve of the battery using the positive electrode active material of Example 1, and the dotted line shows the charge / discharge curve of the battery using the positive electrode active material of Comparative Example 1. As shown in FIG. 2, the battery using the positive electrode active material containing NiO (Example 1) had a higher discharge capacity than the battery using the positive electrode active material containing no NiO (Comparative Example 1).
　実施例１の溶融塩法では、反応工程を、通常の加熱時間よりも短い２時間とした。比較例１の固相法では、加熱時間を通常よりも長くしている。固相法でも、加熱時間を短くすれば、ＮｉＯが反応系に残ると推定される。 In the molten salt method of Example 1, the reaction step was 2 hours shorter than the normal heating time. In the solid phase method of Comparative Example 1, the heating time is set longer than usual. Even in the solid phase method, it is estimated that NiO remains in the reaction system if the heating time is shortened.
　以上の実験より、ＮｉＯを反応系に含む場合には、高温・長時間の合成が必要なく、高い電池容量の正極活物質を得ることができることがわかる。 From the above experiments, it can be seen that when NiO is included in the reaction system, a high-capacity positive electrode active material can be obtained without the need for high-temperature and long-time synthesis.
　（実施例２）
　本実施例では、以下のように、溶融塩法でＬｉ２ＭｎＯ３・ＬｉＮｉ１／３Ｃｏ１／３Ｍｎ１／３Ｏ２を主成分とする正極活物質を作製した。 (Example 2)
In this example, a positive electrode active material mainly composed of Li 2 MnO 3 .LiNi 1/3 Co 1/3 Mn 1/3 O 2 was prepared by the molten salt method as follows.
　混合工程において、リチウム化合物原料（溶融塩原料）として０．２０ｍｏｌの水酸化リチウム－水和物ＬｉＯＨ・Ｈ２Ｏと、ニッケル化合物原料として０．０２ｍｏｌのニッケルマンガンコバルト酸化物とを混合して、原料混合物を調製した。 In the mixing step, 0.20 mol of lithium hydroxide-hydrate LiOH.H 2 O as a lithium compound raw material (molten salt raw material) and 0.02 mol of nickel manganese cobalt oxide as a nickel compound raw material were mixed, A raw material mixture was prepared.
　反応工程において、原料混合物を坩堝に入れて、７００℃の電気炉内に移し、大気中７００℃で２時間加熱した。このとき原料混合物は、融解して溶融塩となり、黒色の生成物が沈殿した。 In the reaction process, the raw material mixture was put in a crucible, transferred into an electric furnace at 700 ° C., and heated in the atmosphere at 700 ° C. for 2 hours. At this time, the raw material mixture melted to form a molten salt, and a black product was precipitated.
　回収工程において、溶融塩の入った坩堝を電気炉内で室温まで冷却した後、電気炉から取り出した。溶融塩が十分に冷却されて固化した後、坩堝ごと２００ｍｌのイオン交換水に浸し、攪拌することで固化した溶融塩を水に溶解した。黒色の生成物は水に対して不溶性であるため、水は黒色の懸濁液となった。黒色の懸濁液を濾過すると、透明な濾液と、濾紙上に黒色の固体の濾物とが得られた。得られた濾物を更にアセトンを用いて十分に洗浄しながら濾過した。洗浄後の黒色の固体を１２０℃で１２時間、真空乾燥した後、乳鉢と乳棒を用いて粉砕した。 In the recovery process, the crucible containing the molten salt was cooled to room temperature in the electric furnace and then taken out from the electric furnace. After the molten salt was sufficiently cooled and solidified, the crucible was immersed in 200 ml of ion exchange water, and the molten salt solidified by stirring was dissolved in water. Since the black product was insoluble in water, the water became a black suspension. Filtration of the black suspension gave a clear filtrate and a black solid filtrate on the filter paper. The obtained filtrate was further filtered while thoroughly washing with acetone. The black solid after washing was vacuum-dried at 120 ° C. for 12 hours and then pulverized using a mortar and pestle.
　得られた黒色粉末について、ＣｕＫα線を用いたＸ線回折（ＸＲＤ）測定を行った。図３（ａ）にＸ線回折測定結果を示した。図３（ａ）に示すように、Ｌｉ２ＭｎＯ３・ＬｉＮｉ１／３Ｃｏ１／３Ｍｎ１／３Ｏ２の面指数（ｈ，ｋ，ｌ）＝（０，０，１）に由来するピーク（２θ＝１８．６９５°）が確認され、更にＮｉＯの面指数（ｈ，ｋ，ｌ）＝（２，０，０）に由来するピークも２θ＝４３．３６３°で確認された。Ｌｉ２ＭｎＯ３・ＬｉＮｉ１／３Ｃｏ１／３Ｍｎ１／３Ｏ２の面指数（ｈ，ｋ，ｌ）＝（０，０，１）に由来するピークの強度に対するＮｉＯの面指数（ｈ，ｋ，ｌ）＝（２，０，０）に由来するピークの強度の比率は、１０％であった。このことから、複合酸化物（Ｌｉ２ＭｎＯ３－ＬｉＮｉＯ２）１００質量部に対するＮｉＯの含有量は、７．７質量部であることがわかった。 The obtained black powder was subjected to X-ray diffraction (XRD) measurement using CuKα rays. FIG. 3A shows the result of X-ray diffraction measurement. As shown in FIG. 3 (a), derived from Li 2 MnO 3 · LiNi 1/3 Co 1/3 Mn 1/3 O 2 of plane indices (h, k, l) = a (0, 0, 1) A peak (2θ = 18.695 °) was confirmed, and a peak derived from the plane index (h, k, l) = (2, 0, 0) of NiO was also confirmed at 2θ = 43.363 °. The surface index of NiO with respect to the intensity of the peak derived from the surface index (h, k, l) = (0, 0, 1) of Li 2 MnO 3 · LiNi 1/3 Co 1/3 Mn 1/3 O 2 , K, l) = (2, 0, 0), the ratio of the intensity of the peak was 10%. From this, it was found that the content of NiO with respect to 100 parts by mass of the composite oxide (Li 2 MnO 3 —LiNiO 2 ) was 7.7 parts by mass.
　（比較例２）
　本比較例では、以下のように、固相法でＬｉ２ＭｎＯ３・ＬｉＮｉ１／３Ｃｏ１／３Ｍｎ１／３Ｏ２を主成分とする正極活物質を作製した。 (Comparative Example 2)
In this comparative example, a positive electrode active material mainly composed of Li 2 MnO 3 .LiNi 1/3 Co 1/3 Mn 1/3 O 2 was produced by a solid phase method as follows.
　混合工程において、リチウム化合物原料として０．１０ｍｏｌの水酸化リチウム－水和物ＬｉＯＨ・Ｈ２Ｏと、ニッケル化合物原料として０．１０ｍｏｌのニッケルマンガンコバルト酸化物とを混合して、原料混合物を調製した。 In the mixing step, a raw material mixture was prepared by mixing 0.10 mol of lithium hydroxide-hydrate LiOH.H 2 O as a lithium compound raw material and 0.10 mol of nickel manganese cobalt oxide as a nickel compound raw material. .
　反応工程において、原料混合物を乳鉢でよく混合した後に、坩堝に入れて、酸素雰囲気（酸素ガス含有量１００％）中、１０００℃で１２時間加熱した。得られた粉末を乳鉢と乳棒を用いて粉砕した後、坩堝に入れて、更に酸素雰囲気（酸素ガス濃度１００％）中、１０００℃で１２時間加熱した。 In the reaction step, the raw material mixture was mixed well in a mortar, then placed in a crucible and heated at 1000 ° C. for 12 hours in an oxygen atmosphere (oxygen gas content 100%). The obtained powder was pulverized using a mortar and pestle, placed in a crucible, and further heated at 1000 ° C. for 12 hours in an oxygen atmosphere (oxygen gas concentration 100%).
　得られた黒色粉末についてＸ線としてＣｕＫα線を用いたＸ線回折（ＸＲＤ）を測定し、図３（ｂ）に示した。図３（ｂ）に示すように、Ｌｉ２ＭｎＯ３・ＬｉＮｉ１／３Ｃｏ１／３Ｍｎ１／３Ｏ２の面指数（ｈ，ｋ，ｌ）＝（０，０，１）に由来するピークは確認されたが、ＮｉＯの面指数（ｈ，ｋ，ｌ）＝（２，０，０）に由来するピークは確認されなかった。 The obtained black powder was measured for X-ray diffraction (XRD) using CuKα rays as X-rays and shown in FIG. As shown in FIG. 3 (b), from Li 2 MnO 3 · LiNi 1/3 Co 1/3 Mn 1/3 O 2 of plane indices (h, k, l) = a (0, 0, 1) Although the peak was confirmed, the peak derived from the surface index (h, k, l) = (2, 0, 0) of NiO was not confirmed.
　＜実験２＞
　実施例２及び比較例２の粉末を正極活物質として用いて、上記実験１と同様にリチウム二次電池を作製し、充放電容量を測定した。測定結果を図４に示した。図４において、実線は実施例２の正極活物質を用いた電池の充放電曲線を示し、点線は比較例２の正極活物質を用いた電池の充放電曲線を示す。図４に示すように、ＮｉＯを含む正極活物質（実施例２）を用いた電池の方が、ＮｉＯを含まない正極活物質（比較例２）を用いた電池よりも放電容量が高かった。 <Experiment 2>
Using the powders of Example 2 and Comparative Example 2 as the positive electrode active material, lithium secondary batteries were produced in the same manner as in Experiment 1, and the charge / discharge capacity was measured. The measurement results are shown in FIG. In FIG. 4, the solid line shows the charge / discharge curve of the battery using the positive electrode active material of Example 2, and the dotted line shows the charge / discharge curve of the battery using the positive electrode active material of Comparative Example 2. As shown in FIG. 4, the battery using the positive electrode active material containing NiO (Example 2) had a higher discharge capacity than the battery using the positive electrode active material containing no NiO (Comparative Example 2).

Claims (13)

  1. 　少なくともリチウム（Ｌｉ）元素及びニッケル（Ｎｉ）元素を含み結晶構造が層状岩塩構造に属するリチウムニッケル系複合酸化物と、ニッケル酸化物とを有し、前記ニッケル酸化物は、前記リチウムニッケル系複合酸化物を製造する原料の一部又は該原料より生成した副生成物であることを特徴とする非水電解質二次電池用正極活物質。 A lithium-nickel composite oxide containing at least lithium (Li) element and nickel (Ni) element and having a crystal structure belonging to a layered rock salt structure; and nickel oxide, wherein the nickel oxide is the lithium-nickel composite oxide A positive electrode active material for a non-aqueous electrolyte secondary battery, which is a part of a raw material for producing a product or a by-product generated from the raw material.
  2. 　前記リチウムニッケル系複合酸化物及び前記ニッケル酸化物は、それぞれ粒子を構成している請求項１記載の非水電解質二次電池用正極活物質。 The positive electrode active material for a non-aqueous electrolyte secondary battery according to claim 1, wherein the lithium nickel composite oxide and the nickel oxide each constitute particles.
  3. 　前記リチウムニッケル系複合酸化物は、組成式：ｘＬｉ２Ｍ１Ｏ３・（１―ｘ）ＬｉＮｉｙＭ２ １－ｙＯ２（０≦ｘ＜１、０＜ｙ≦１、Ｍ１は、４価のＭｎを必須とする１種以上の金属元素、Ｍ２は、金属元素、Ｌｉはその一部が水素で置換されていてもよい。）で表される複合酸化物を基本組成とする請求項１に記載の非水電解質二次電池用正極活物質。 The lithium nickel-based composite oxide has a composition formula: xLi 2 M 1 O 3. (1-x) LiNi y M 2 1-y O 2 (0 ≦ x <1, 0 <y ≦ 1, M 1 is One or more metal elements essentially containing tetravalent Mn, M 2 is a metal element, and Li may be partially substituted with hydrogen.) The positive electrode active material for nonaqueous electrolyte secondary batteries according to claim 1.
  4. 前記組成式：ｘＬｉ２Ｍ１Ｏ３・（１―ｘ）ＬｉＮｉｙＭ２ １－ｙＯ２中のＬｉ２Ｍ１Ｏ３は、Ｌｉ２ＭｎＯ３からなる請求項３記載の非水電解質二次電池用正極活物質。 The composition formula: xLi 2 M 1 O 3 · (1-x) LiNi y M 2 1-y O 2 Li 2 M 1 O 3 in a non-aqueous electrolyte secondary of claim 3, wherein comprising a Li 2 MnO 3 Positive electrode active material for secondary battery.
  5. 前記組成式：ｘＬｉ２Ｍ１Ｏ３・（１―ｘ）ＬｉＮｉｙＭ２ １－ｙＯ２中のＬｉＮｉｙＭ２ １－ｙＯ２は、ＬｉＮｉＯ２、ＬｉＮｉ１／３Ｍｎ１／３Ｃｏ１／３Ｏ２、ＬｉＮｉ１／２Ｍｎ１／２Ｏ２、及びＬｉＮｉ１／２Ｃｏ１／２Ｏ２の群から選ばれる１種からなる請求項３記載の非水電解質二次電池用正極活物質。 LiNi y M 2 1-y O 2 in the composition formula: xLi 2 M 1 O 3. (1-x) LiNi y M 2 1-y O 2 is LiNiO 2 , LiNi 1/3 Mn 1/3 Co The positive electrode for a non-aqueous electrolyte secondary battery according to claim 3, comprising one type selected from the group consisting of 1/3 O 2 , LiNi 1/2 Mn 1/2 O 2 , and LiNi 1/2 Co 1/2 O 2. Active material.
  6. 前記組成式：ｘＬｉ２Ｍ１Ｏ３・（１－ｘ）ＬｉＮｉｙＭ２ １－ｙＯ２で表される複合酸化物は、ＬｉＮｉＯ２、Ｌｉ２ＭｎＯ３・ＬｉＮｉＯ２、Ｌｉ２ＭｎＯ３・ＬｉＮｉ１／３Ｍｎ１／３Ｃｏ１／３Ｏ２、Ｌｉ２ＭｎＯ３・ＬｉＮｉ１／２Ｍｎ１／２Ｏ２、及びＬｉ２ＭｎＯ３・ＬｉＮｉ１／２Ｃｏ１／２Ｏ２の群から選ばれる１種からなる請求項３記載の非水電解質二次電池用正極活物質。 The composite oxide represented by the composition formula: xLi 2 M 1 O 3. (1-x) LiNi y M 2 1-y O 2 is LiNiO 2 , Li 2 MnO 3 .LiNiO 2 , Li 2 MnO 3. From the group of LiNi 1/3 Mn 1/3 Co 1/3 O 2 , Li 2 MnO 3 .LiNi 1/2 Mn 1/2 O 2 , and Li 2 MnO 3 .LiNi 1/2 Co 1/2 O 2 The positive electrode active material for a non-aqueous electrolyte secondary battery according to claim 3, comprising one selected.
  7. 　前記リチウムニッケル系複合酸化物を１００質量部としたときに、前記ニッケル酸化物が、５質量部以上３０質量部以下含まれる請求項１記載の非水電解質二次電池用正極活物質。 The positive electrode active material for a nonaqueous electrolyte secondary battery according to claim 1, wherein the nickel oxide is contained in an amount of 5 parts by mass to 30 parts by mass when the lithium nickel composite oxide is 100 parts by mass.
  8. 　ＣｕＫα線を光源とするＸ線回折測定を行って作成された前記正極活物質のＸ線回折図形において、前記リチウムニッケル系複合酸化物の面指数（ｈ，ｋ，ｌ）＝（０，０，１）のピーク強度に対する、前記ニッケル酸化物の面指数（ｈ，ｋ，ｌ）＝（２，０，０）のピーク強度の比率は、０．１％以上２０％未満である請求項１記載の非水電解質二次電池用正極活物質。 In the X-ray diffraction pattern of the positive electrode active material prepared by performing X-ray diffraction measurement using CuKα rays as a light source, the plane index (h, k, l) of the lithium nickel-based composite oxide = (0, 0, The ratio of the peak intensity of the plane index (h, k, l) = (2, 0, 0) of the nickel oxide to the peak intensity of 1) is 0.1% or more and less than 20%. The positive electrode active material for nonaqueous electrolyte secondary batteries.
  9. 　請求項１に記載の非水電解質二次電池用正極活物質の製造方法であって、
    　ニッケルを必須とする一種以上の金属元素を含む酸化物、水酸化物及び金属塩から選ばれる一種以上の金属化合物を含むニッケル化合物原料と、リチウムを必須とする一種以上の金属元素を含む酸化物、水酸化物及び金属塩から選ばれる一種以上の金属化合物を含むリチウム化合物原料とを加熱して、前記ニッケル化合物原料から生成したニッケル酸化物を残した状態で前記ニッケル化合物原料と前記リチウム化合物原料とを反応させて前記リチウムニッケル系複合酸化物を得る反応工程をもつことを特徴とする非水電解質二次電池用正極活物質の製造方法。     It is a manufacturing method of the positive electrode active material for nonaqueous electrolyte secondary batteries according to claim 1,
    Nickel compound raw material containing one or more metal compounds selected from oxides, hydroxides and metal salts containing one or more metal elements essential for nickel, and oxide containing one or more metal elements essential for lithium The nickel compound raw material and the lithium compound raw material are heated in a state where one or more metal compounds selected from hydroxides and metal salts are heated to leave the nickel oxide generated from the nickel compound raw material. A method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery, comprising a reaction step of obtaining the lithium nickel composite oxide by reacting
  10. 　前記リチウム化合物原料と前記ニッケル化合物原料とを混合して原料混合物を調製する混合工程を行い、前記反応工程での前記原料混合物の加熱は、溶融塩法で行う請求項９記載の非水電解質二次電池用正極活物質の製造方法。 The non-aqueous electrolyte 2 according to claim 9, wherein a mixing step of preparing the raw material mixture by mixing the lithium compound raw material and the nickel compound raw material is performed, and heating of the raw material mixture in the reaction step is performed by a molten salt method. A method for producing a positive electrode active material for a secondary battery.
  11. 　前記反応工程の後には、前記リチウムニッケル系複合酸化物を徐冷してから回収する回収工程を行う請求項９記載の非水電解質二次電池用正極活物質の製造方法。 10. The method for producing a positive electrode active material for a nonaqueous electrolyte secondary battery according to claim 9, wherein after the reaction step, a recovery step is performed in which the lithium nickel composite oxide is gradually cooled and then recovered.
  12. 　請求項１に記載の非水電解質二次電池用正極活物質を含む正極と、負極と、非水電解質と、を備えることを特徴とする非水電解質二次電池。 A nonaqueous electrolyte secondary battery comprising: a positive electrode including the positive electrode active material for a nonaqueous electrolyte secondary battery according to claim 1; a negative electrode; and a nonaqueous electrolyte.
  13. 　請求項１２に記載の非水電解質二次電池を搭載したことを特徴とする車両。 A vehicle comprising the non-aqueous electrolyte secondary battery according to claim 12 mounted thereon.
PCT/JP2012/000084 2011-03-14 2012-01-10 Cathode active material for non-aqueous electrolyte secondary battery, method for producing same, and non-aqueous electrolyte secondary battery using same WO2012124242A1 (en)

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