WO2020246064A1 - Positive electrode active material, and cell - Google Patents

Positive electrode active material, and cell Download PDF

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Publication number
WO2020246064A1
WO2020246064A1 PCT/JP2020/001204 JP2020001204W WO2020246064A1 WO 2020246064 A1 WO2020246064 A1 WO 2020246064A1 JP 2020001204 W JP2020001204 W JP 2020001204W WO 2020246064 A1 WO2020246064 A1 WO 2020246064A1
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Prior art keywords
electrode active
active material
positive electrode
battery
material according
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PCT/JP2020/001204
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French (fr)
Japanese (ja)
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孝紀 大前
修平 内田
岳史 大尾
竜一 夏井
友 大塚
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パナソニックＩｐマネジメント株式会社
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0561—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of inorganic materials only
    • H01M10/0562—Solid materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0565—Polymeric materials, e.g. gel-type or solid-type
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/134—Electrodes based on metals, Si or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present disclosure relates to a positive electrode active material for a battery and a battery.
  • Patent Document 1 discloses a positive electrode active material for a secondary battery.
  • the positive electrode active material includes a core; a shell located surrounding the core; and a cushioning layer located between the core and the shell and containing a three-dimensional network structure connecting the core and the shell and voids.
  • the three-dimensional network structure in the core, shell, and buffer layer is represented by the chemical formula Li a Ni 1-xy Co x M1 y M3 z M2 w O 2 , each containing a plurality of crystal grains independently. Contains polycrystalline lithium composite metal oxide. The crystal grains have an average crystal size of 50 nm to 150 nm.
  • M1 contains any one or more elements selected from the group consisting of Al and Mn.
  • M2 comprises any one or more elements selected from the group consisting of Zr, Ti, Mg, Ta and Nb.
  • M3 comprises any one or more elements selected from the group consisting of W, Mo and Cr.
  • a, x, y, z, and w are 1.0 ⁇ a ⁇ 1.5, 0 ⁇ x ⁇ 0.5, 0 ⁇ y ⁇ 0.5, 0.0005 ⁇ z ⁇ 0.03, 0 ⁇ Satisfy w ⁇ 0.02 and 0 ⁇ x + y ⁇ 0.7.
  • the positive electrode active material in the uniform state of the present disclosure contains particles of a lithium composite oxide having a crystal structure belonging to a layered structure, and the particles are arranged radially from the center of the particles toward the surface, and a plurality of columns are arranged.
  • the c-axis of the crystal structure is oriented in the major axis direction of the crystal aggregate, and the a-axis of the crystal structure is in the minor axis direction of the crystal aggregate. Oriented.
  • a high capacity battery can be realized.
  • FIG. 1 is a diagram showing a structural model of a part of the particles for explaining the structure of the particles of the lithium composite oxide contained in the positive electrode active material in the first embodiment.
  • FIG. 2 is a cross-sectional view showing a schematic configuration of a battery 10 which is an example of the battery according to the second embodiment.
  • FIG. 3A is a scanning transmission electron microscope (STEM) cross-sectional image of the lithium composite oxide particles of Example 1.
  • FIG. 3B is an atomic resolution image of the region 30 portion shown in FIG. 3A.
  • FIG. 4 is a scanning electron microscope (SEM) cross-sectional image of the lithium composite oxide particles of Comparative Example 1.
  • the positive electrode active material in the first embodiment contains particles of a lithium composite oxide having a crystal structure belonging to a layered structure.
  • the particles of the lithium composite oxide include a plurality of columnar crystal aggregates arranged radially from the center of the particles toward the surface.
  • the c-axis of the crystal structure belonging to the layered structure is oriented in the major axis direction of the crystal aggregate, and the a-axis is oriented in the minor axis direction of the crystal aggregate.
  • the columnar crystal aggregate is an aggregate of a plurality of crystals having a crystal structure belonging to a layered structure, and the overall shape of this aggregate is columnar.
  • the c-axis of the crystal structure belonging to the layered structure is oriented in the major axis direction of the crystal aggregate, and the a-axis is oriented in the minor axis direction of the crystal aggregate. Therefore, for example, it can be said that a columnar crystal aggregate is composed of a plurality of crystals having a crystal structure belonging to a layered structure in which the crystal orientations coincide with each other.
  • the positive electrode active material in the first embodiment is, for example, a positive electrode active material for a lithium ion battery.
  • the lithium ion battery has an oxidation-reduction potential (Li / Li + reference) of about 3.4 V.
  • the lithium ion battery has a capacity of about 260 mAh / g or more.
  • FIG. 1 is a diagram showing a structural model of a part of the particles for explaining the structure of the particles of the lithium composite oxide contained in the positive electrode active material in the first embodiment.
  • the lithium composite oxide particle 1 contains a plurality of columnar crystal aggregates 2.
  • the plurality of columnar crystal aggregates 2 are arranged radially from the center of the particle 1 toward the surface.
  • the crystal aggregates 2 may be arranged in a radial order from the center of the particles 1 toward the surface.
  • the crystal aggregates 2 may be arranged radially from the center of the particles 1 toward the surface.
  • the lithium composite oxide in particle 1 has a crystal structure belonging to a layered structure. Therefore, the crystals constituting the columnar crystal aggregate 2 have a crystal structure belonging to the layered structure.
  • the c-axis of the crystal structure belonging to the layered structure is oriented in the major axis direction 3 of the crystal assembly 2, and the a-axis is oriented in the minor axis direction 4 of the crystal assembly 2. It is oriented. Since the crystal aggregate 2 is composed of crystals having such an orientation, a diffusion path of Li is formed in the crystal aggregate 2 along the minor axis direction 4.
  • the lithium composite oxide particle 1 having the above structure Li can easily reach the inside of the particle through the gap between the crystal aggregates 2 adjacent to each other, and Li can be easily reached from the inside of the particle to the outside of the particle. You can get out. Further, since the diffusion path of Li is formed along the minor axis direction 4, the moving distance of Li when the Li diffuses into the positive electrode active material is short. For this reason, the positive electrode active material containing the lithium composite oxide particles 1 can improve the capacity and output of the battery.
  • the positive electrode active material described in Patent Document 1 will be examined.
  • the positive electrode active material described in Patent Document 1 has a core portion, a shell portion located around the core portion, and a buffer layer existing in a gap between the core portion and the shell portion.
  • the shell portion contains particles of crystal-oriented polycrystalline lithium composite metal oxide grown radially from the center of the positive electrode active material toward the surface.
  • the positive electrode active material described in Patent Document 1 does not include a columnar crystal aggregate composed of crystals having an orientation like the positive electrode active material in the first embodiment of the present disclosure.
  • the positive electrode active material described in Patent Document 1 a crystal aggregate having a crystal structure in which the a-axis direction is parallel to the minor axis direction and the c-axis direction is parallel to the major axis direction has been realized. No suggestion is made for such a structure. That is, the lithium composite oxide contained in the positive electrode active material according to the first embodiment does not exist in the past and has a structure that cannot be easily reached from the prior art. As a result, the positive electrode active material in the first embodiment can realize a high-capacity battery.
  • the length of the minor axis of the columnar crystal aggregate is X nm
  • X may satisfy 10 ⁇ X ⁇ 500.
  • the length of the minor axis of the columnar crystal aggregate means the maximum length of the columnar crystal aggregate in the minor axis direction.
  • the maximum length of the columnar crystal aggregate in the minor axis direction corresponds to the length in the minor axis direction of the columnar crystal aggregate in the vicinity of the surface of the lithium composite oxide particles. According to this configuration, the distance at which Li diffuses becomes short. Therefore, a higher capacity battery can be realized.
  • X may satisfy 20 ⁇ X ⁇ 250. According to this configuration, the distance at which Li diffuses becomes short. Therefore, a higher capacity battery can be realized.
  • Y may satisfy 1 ⁇ Y ⁇ 15.
  • the length of the major axis of the columnar crystal aggregate may correspond to, for example, the radius of the particles of the lithium composite oxide.
  • the lithium composite oxide particles have a crystal structure belonging to the layered structure as described above.
  • the crystal structure belonging to this layered structure may belong to at least one selected from the group consisting of the space group C2 / m and the space group R-3m.
  • the crystal structure belonging to this layered structure may be a mixed phase including both a phase belonging to the space group C2 / m and a phase belonging to the space group R-3m. According to this configuration, the diffusibility of Li is further improved, so that a battery having a higher capacity can be realized.
  • the crystal structure belonging to the space group C2 / m has a structure in which Li layers and transition metal layers (layers occupied by "cation elements such as transition metals") are alternately laminated. Further, the transition metal layer can contain Li in addition to "cationic elements such as transition metals". Therefore, the crystal structure belonging to the space group C2 / m can occlude more Li in the crystal structure than the general conventional material LiCoO 2 .
  • the crystal structure belonging to the space group R-3m also has a structure in which Li layers and transition metal layers are alternately laminated.
  • the crystal structure belonging to the space group R-3m has a high diffusion property of Li because the diffusion path of Li exists two-dimensionally.
  • the space group to which the crystal structure of the lithium composite oxide of the positive electrode active material in the first embodiment belongs can be specified by, for example, X-ray diffraction (XRD) measurement or electron beam diffraction measurement.
  • XRD X-ray diffraction
  • the lithium composite oxide particles may have a void layer inside.
  • the area where the electrolytic solution comes into contact with the particles becomes large, and the diffusibility of Li into the particles is further improved.
  • the particles of the lithium composite oxide have a void layer
  • the portion inside the void layer may be regarded as the core portion of the particles, and the portion outside the void layer may be regarded as the shell portion of the particles.
  • the lithium composite oxide particles may have a plurality of void layers.
  • the inner portion of the void layer having the largest thickness may be regarded as the core portion and the outer portion may be regarded as the shell portion.
  • the lithium composite oxide may contain at least one selected from the group consisting of F, Cl, N, and S.
  • the crystal structure is stabilized by substituting a part of oxygen with an electrochemically inactive anion. Further, it is considered that the crystal lattice is expanded and the diffusibility of Li is improved by substituting a part of oxygen with an anion having a large ionic radius. Therefore, it is considered that more Li can be inserted and removed. Therefore, a high-capacity battery can be realized.
  • the lithium composite oxide contains at least one element selected from the group consisting of F, Cl, N, and S
  • the amount of oxygen redox is large. Not too much. Therefore, it is considered that the capacity or cycle characteristics are improved because the crystal structure is suppressed from becoming unstable due to oxygen desorption.
  • the lithium composite oxide may contain F.
  • the lithium composite oxide is a "cationic element such as a transition metal" other than lithium, for example, Mn, Co, Ni, Fe, Cu, V, Nb, Mo, Ti. , Cr, Zr, Zn, Na, K, Ca, Mg, Pt, Au, Ag, Ru, W, B, Si, P, and Al, which may contain at least one selected from the group.
  • a transition metal such as a transition metal
  • the lithium composite oxide is, for example, Mn, Co, Ni, Fe, Cu, V, Ti, Cr, and Zn as the above-mentioned "cation elements such as transition metals". It may contain at least one selected from the group consisting of, i.e., at least one 3d transition metal element.
  • the lithium composite oxide is at least one selected from the group consisting of, for example, Mn, Co, Ni, and Al as the above-mentioned "cationic element such as a transition metal”. May include.
  • the lithium composite oxide may contain Mn.
  • the average composition of the lithium composite oxide may be represented by the following composition formula (1).
  • Me is Mn, Co, Ni, Fe, Cu, V, Nb, Mo, Ti, Cr, Zr, Zn, Na, K, Ca, Mg, Pt, Au, Ag, Ru, W, B, It may be at least one selected from the group consisting of Si, P, and Al.
  • Q may be at least one selected from the group consisting of F, Cl, N, and S.
  • composition formula (1) is based on the following conditions. 1.05 ⁇ x ⁇ 1.5, 0.6 ⁇ y ⁇ 1.0, 1.2 ⁇ ⁇ ⁇ 2.0, and 0 ⁇ ⁇ 0.8, May be satisfied.
  • composition formula (1) when x is 1.05 or more, the amount of Li that can be used increases. Therefore, the capacity is improved.
  • composition formula (1) when x is 1.5 or less, the redox reaction of Me that can be used increases. As a result, it is not necessary to utilize a lot of oxygen redox reactions. This stabilizes the crystal structure. Therefore, the capacity is improved.
  • composition formula (1) when y is 0.6 or more, the redox reaction of Me that can be used increases. As a result, it is not necessary to utilize a lot of oxygen redox reactions. This stabilizes the crystal structure. Therefore, the capacity is improved.
  • composition formula (1) when y is 1.0 or less, the amount of Li that can be used increases. Therefore, the capacity is improved.
  • composition formula (1) when ⁇ is 1.2 or more, it is possible to prevent the charge compensation amount due to the redox of oxygen from decreasing. Therefore, the capacity is improved.
  • composition formula (1) when ⁇ is 2.0 or less, it is possible to prevent the capacity due to redox of oxygen from becoming excessive, and the structure is stabilized when Li is eliminated. Therefore, the capacity is improved.
  • composition formula (1) when ⁇ is larger than 0, the structure is stabilized when Li is eliminated due to the influence of the electrochemically inactive Q. Therefore, the capacity is improved.
  • composition formula (1) when ⁇ is 0.8 or less, it is possible to prevent the influence of the electrochemically inactive Q from becoming large, so that the electron conductivity is improved. Therefore, the capacity is improved.
  • the "average composition" of the lithium composite oxide in the first embodiment is a composition obtained by performing elemental analysis on the lithium composite oxide without considering the difference in the composition of each phase. Typically, it means the composition obtained by performing elemental analysis using a sample as large as or larger than the size of the primary particles of the lithium composite oxide.
  • the above-mentioned average composition can be determined by ICP emission spectroscopy, inert gas melting-infrared absorption method, ion chromatography, or a combination of these analysis methods.
  • Me is at least one selected from the group consisting of Mn, Co, Ni, Fe, Cu, V, Ti, Cr, and Zn, that is, at least one 3d transition metal. It may contain elements.
  • Me may contain at least one selected from the group consisting of Mn, Co, Ni, and Al.
  • Me may contain Mn.
  • Me may be Mn.
  • Me is Co, Ni, Fe, Cu, V, Nb, Mo, Ti, Cr, Zr, Zn, Na, K, Ca, Mg, Pt, Au, Ag, Ru, W, B, Si, P. , And at least one element selected from the group consisting of Al, and Mn may be contained.
  • the ratio of Mn to Me may be 59.9 mol% or more. That is, the mol ratio (Mn / Me ratio) of Mn to the entire Me containing Mn may satisfy the relationship of 0.599 to 1.0.
  • oxygen desorption during charging is further suppressed by containing a large amount of Mn, which easily hybridizes with oxygen. Therefore, a higher capacity battery can be realized.
  • Me may contain at least one selected from the group consisting of B, Si, P, and Al in an amount of 20 mol% or less based on Me.
  • the structure is stabilized by containing an element having a high covalent bond property, so that the cycle characteristics are improved. Therefore, a battery having a longer life can be realized.
  • Q may include F.
  • Q may be F.
  • Q may contain at least one element selected from the group consisting of Cl, N, and S, and F.
  • composition formula (1) is based on the following conditions. 1.166 ⁇ x ⁇ 1.23, and 0.77 ⁇ y ⁇ 0.834, May be satisfied.
  • composition formula (1) is based on the following conditions. 1.9 ⁇ ⁇ ⁇ 1.917, 0.083 ⁇ ⁇ ⁇ 0.1, May be satisfied.
  • the ratio of "Li” and “Me” is represented by x / y.
  • composition formula (1) may satisfy 1.39 ⁇ x / y ⁇ 1.6.
  • the ratio of the number of Li atoms at the site where Li is located is higher than that of the conventional positive electrode active material represented by the composition formula LiMnO 2 . This makes it possible to insert and remove more Li.
  • composition formula (1) may satisfy 1.5 ⁇ x / y ⁇ 1.6.
  • composition formula (1) may satisfy 19 ⁇ ⁇ / ⁇ ⁇ 23.1.
  • ⁇ / ⁇ is 23.1 or less, it is possible to prevent the capacity from becoming excessive due to redox of oxygen, and the structure is stabilized when Li is eliminated. Further, due to the influence of the electrochemically inert Q, the structure is stabilized when Li is eliminated. Therefore, a higher capacity battery can be realized.
  • the ratio of "Li + Me” and “O + Q” (that is, the ratio of "cation” and “anion") is represented by (x + y) / ( ⁇ + ⁇ ).
  • composition formula (1) may satisfy 0.75 ⁇ (x + y) / ( ⁇ + ⁇ ) ⁇ 1.2.
  • composition formula (1) may satisfy 1.0 ⁇ (x + y) / ( ⁇ + ⁇ ) ⁇ 1.2.
  • a part of Li in the lithium composite oxide may be replaced with an alkali metal such as Na or K.
  • the positive electrode active material in the first embodiment may contain the above-mentioned lithium composite oxide particles as a main component (that is, 50% or more (50% by mass or more) in mass ratio with respect to the whole positive electrode active material). Good.
  • the positive electrode active material in the first embodiment may contain the above-mentioned lithium composite oxide particles in a mass ratio of 70% or more (70% by mass or more) with respect to the whole positive electrode active material.
  • the positive electrode active material in the first embodiment may contain the above-mentioned lithium composite oxide particles in a mass ratio of 90% or more (90% by mass or more) with respect to the whole positive electrode active material.
  • the positive electrode active material in the first embodiment may contain unavoidable impurities while containing the above-mentioned lithium composite oxide particles.
  • the positive electrode active material in the first embodiment is composed of a group consisting of a starting material, a by-product, and a decomposition product used for synthesizing the positive electrode active material while containing the above-mentioned lithium composite oxide particles. It may contain at least one selected.
  • the positive electrode active material in the first embodiment may contain only the above-mentioned lithium composite oxide particles, for example, excluding impurities inevitably mixed.
  • the lithium composite oxide can be produced, for example, by the following method.
  • MeCO 3 is prepared.
  • Raw materials for producing this precursor include MeSO 4 , Me (NO 3 ) 2 , Me (CH 3 COO) 2, and other Me-containing compounds, and Na 2 CO 3 , K 2 CO 3 , and Na HCO 3 , Examples include carbonates such as KHCO 3 and the like.
  • Me is Mn
  • examples of the raw material containing Mn include MnSO 4 , Mn (NO 3 ) 2 , Mn (CH 3 COO) 2, and the like.
  • a solution A containing a Me source is prepared by dissolving a compound containing Me in pure water so as to have a predetermined concentration (for example, 2 mol / L). Further, by dissolving the carbonic acid source in pure water so as to have a predetermined concentration (for example, 2 mol / L), a solution B containing the carbonic acid source is prepared.
  • MeCO 3 as a precursor can be obtained by dropping the two prepared solutions A and B into pure water while controlling the pH.
  • the solution B may contain a complex-forming agent such as NH 3 .
  • a raw material containing Li, the above-mentioned MeCO 3 as a precursor, and a raw material containing Q are prepared.
  • Examples of the raw material containing Li include oxides such as Li 2 O and Li 2 O 2 , salts such as LiF, Li 2 CO 3 and LiOH, and lithium composite oxides such as LiMeO 2 and LiMe 2 O 4 . Can be mentioned.
  • Examples of the raw material containing Q include lithium halide, transition metal halide, transition metal sulfide, and transition metal nitride.
  • examples of the raw material containing F include LiF, transition metal fluoride, and the like.
  • These raw materials are weighed so as to have the molar ratio shown in the composition formula (1).
  • the weighed raw materials are mixed, for example, by a dry method or a wet method, and then heat-treated.
  • composition formula (1) By these steps, "x, y, ⁇ , and ⁇ " in the composition formula (1) can be changed within the range represented by the composition formula (1).
  • the conditions of the heat treatment at this time are appropriately set so that the lithium composite oxide according to the first embodiment can be obtained.
  • the optimum conditions for heat treatment depend on other manufacturing conditions and the target composition.
  • the temperature of the heat treatment can be appropriately changed in the range of, for example, 200 to 900 ° C.
  • the time required for the heat treatment can be appropriately changed, for example, in the range of 1 minute to 20 hours.
  • the heat treatment atmosphere may be an air atmosphere, an oxygen atmosphere, or an inert atmosphere such as nitrogen or argon.
  • heat treatment may be performed in several stages instead of one stage.
  • the lithium composite oxide constituting the positive electrode active material according to the first embodiment can be substantially obtained.
  • the space group of the crystal structure of the obtained lithium composite oxide can be specified by, for example, X-ray diffraction measurement or electron diffraction measurement. From this, it can be confirmed that the obtained lithium composite oxide has a crystal structure belonging to the space group C2 / m or R3-m.
  • the average composition of the obtained lithium composite oxide can be determined by, for example, ICP emission spectroscopy, inert gas melting-infrared absorption method, ion chromatography, or a combination of these analysis methods.
  • the step (a) for producing a precursor which is a carbonate of Me and other raw materials excluding Me are prepared.
  • the step (b) is included, and the step (c) of mixing the precursor and the other raw materials and heat-treating the obtained mixture to obtain a lithium composite oxide.
  • the above-mentioned step (c) includes a step of adjusting the mixed raw materials by mixing each of the above-mentioned raw materials at a ratio of Li of 1.39 or more and 1.6 or less with respect to Me. You may.
  • the above-mentioned step (b) may include a step of producing a lithium compound as a raw material by a known method.
  • each of the above-mentioned raw materials is mixed with Me at a molar ratio of Li of 1.5 or more and 1.6 or less to prepare a mixed raw material. It may be included.
  • step (c) may include a step of reacting by heat treatment in two steps.
  • the battery according to the second embodiment includes a positive electrode containing the positive electrode active material according to the first embodiment, a negative electrode, and an electrolyte.
  • the positive electrode may include a positive electrode active material layer.
  • the positive electrode active material layer may contain the positive electrode active material according to the first embodiment as a main component (that is, 50% or more (50% by mass or more) in mass ratio with respect to the entire positive electrode active material layer). Good.
  • the positive electrode active material layer may contain the positive electrode active material of the above-described first embodiment in a mass ratio of 70% or more (70% by mass or more) with respect to the entire positive electrode active material layer. Good.
  • the positive electrode active material layer may contain the positive electrode active material of the above-described first embodiment in a mass ratio of 90% or more (90% by mass or more) with respect to the entire positive electrode active material layer. Good.
  • the battery according to the second embodiment can be configured as, for example, a lithium ion secondary battery, a non-aqueous electrolyte secondary battery, an all-solid-state battery, and the like.
  • the negative electrode may include, for example, a negative electrode active material capable of occluding and releasing lithium ions.
  • the negative electrode may contain, for example, a material capable of dissolving and precipitating lithium metal as the negative electrode active material.
  • the electrolyte may be, for example, a non-aqueous electrolyte (for example, a non-aqueous electrolyte solution).
  • the electrolyte may be, for example, a solid electrolyte.
  • FIG. 2 is a cross-sectional view showing a schematic configuration of a battery 10 which is an example of a battery according to the second embodiment.
  • the battery 10 includes a positive electrode 21, a negative electrode 22, a separator 14, a case 11, a sealing plate 15, and a gasket 18.
  • the separator 14 is arranged between the positive electrode 21 and the negative electrode 22.
  • the positive electrode 21, the negative electrode 22, and the separator 14 are impregnated with, for example, a non-aqueous electrolyte (for example, a non-aqueous electrolyte solution).
  • a non-aqueous electrolyte for example, a non-aqueous electrolyte solution
  • An electrode group is formed by the positive electrode 21, the negative electrode 22, and the separator 14.
  • the electrode group is housed in the case 11.
  • the case 11 is closed by the gasket 18 and the sealing plate 15.
  • the positive electrode 21 includes a positive electrode current collector 12 and a positive electrode active material layer 13 arranged on the positive electrode current collector 12.
  • the positive electrode current collector 12 is made of, for example, a metal material (for example, at least one selected from the group consisting of aluminum, stainless steel, nickel, iron, titanium, copper, palladium, gold, and platinum, or an alloy thereof). Has been done.
  • a metal material for example, at least one selected from the group consisting of aluminum, stainless steel, nickel, iron, titanium, copper, palladium, gold, and platinum, or an alloy thereof. Has been done.
  • the positive electrode active material layer 13 contains the positive electrode active material according to the first embodiment described above.
  • the positive electrode active material layer 13 may contain, for example, an additive (a conductive agent, an ionic conduction auxiliary agent, a binder, etc.), if necessary.
  • an additive a conductive agent, an ionic conduction auxiliary agent, a binder, etc.
  • the negative electrode 22 includes a negative electrode current collector 16 and a negative electrode active material layer 17 arranged on the negative electrode current collector 16.
  • the negative electrode current collector 16 is made of, for example, a metal material (for example, at least one selected from the group consisting of aluminum, stainless steel, nickel, iron, titanium, copper, palladium, gold, and platinum, or an alloy thereof). Has been done.
  • the negative electrode active material layer 17 contains a negative electrode active material.
  • the negative electrode active material layer 17 may contain, for example, additives (conductive agent, ionic conduction auxiliary agent, binder, etc.), if necessary.
  • the negative electrode active material metal materials, carbon materials, oxides, nitrides, tin compounds, silicon compounds, etc. can be used.
  • the metal material may be a single metal.
  • the metal material may be an alloy.
  • metal materials include lithium metal, lithium alloy, and the like.
  • Examples of carbon materials include natural graphite, coke, graphitizing carbon, carbon fiber, spherical carbon, artificial graphite, amorphous carbon, and the like.
  • silicon (Si), tin (Sn), silicon compound, and tin compound can be used as the negative electrode active material.
  • the silicon compound and the tin compound may be alloys or solid solutions, respectively.
  • silicon compounds examples include SiO x (where 0.05 ⁇ x ⁇ 1.95). Further, a compound (alloy or solid solution) obtained by substituting a part of silicon of SiO x with another element can also be used.
  • the other elements are from the group consisting of boron, magnesium, nickel, titanium, molybdenum, cobalt, calcium, chromium, copper, iron, manganese, niobium, tantalum, vanadium, tungsten, zinc, carbon, nitrogen and tin. At least one selected.
  • tin compound examples include Ni 2 Sn 4 , Mg 2 Sn, SnO x (here, 0 ⁇ x ⁇ 2), SnO 2 , SnSiO 3 , and the like.
  • One kind of tin compound selected from these may be used alone. Alternatively, a combination of two or more tin compounds selected from these may be used.
  • the shape of the negative electrode active material is not particularly limited.
  • a negative electrode active material having a known shape can be used.
  • the method for filling (occluding) lithium in the negative electrode active material layer 17 is not particularly limited. Specifically, as this method, (a) a method of depositing lithium on the negative electrode active material layer 17 by a vapor phase method such as a vacuum vapor deposition method, and (b) a lithium metal foil and the negative electrode active material layer 17 are brought into contact with each other. There is a method of heating both. In either method, lithium can be diffused into the negative electrode active material layer 17 by heat. There is also a method of electrochemically storing lithium in the negative electrode active material layer 17. Specifically, the battery is assembled using the negative electrode 22 having no lithium and the lithium metal foil (positive electrode). Then, the battery is charged so that lithium is occluded in the negative electrode 22.
  • binder for the positive electrode 21 and the negative electrode 22 examples include polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, aramid resin, polyamide, polyimide, polyamideimide, polyacrylic nitrile, polyacrylic acid, polyacrylic acid methyl ester, and poly.
  • Acrylic ethyl ester Polyacrylic acid hexyl ester, Polymethacrylic acid, Polymethacrylic acid methyl ester, Polymethacrylic acid ethyl ester, Polymethacrylic acid hexyl ester, Polyvinyl acetate, Polypolypyrrolidone, polyether, Polyether sulfone, Hexafluoro Polypropylene, styrene butadiene rubber, carboxymethyl cellulose, etc. can be used.
  • binder tetrafluoroethylene, hexafluoroethane, hexafluoropropylene, perfluoroalkyl vinyl ether, vinylidene fluoride, chlorotrifluoroethylene, ethylene, propylene, pentafluoropropylene, fluoromethyl vinyl ether, acrylic acid, hexadiene, Copolymers of two or more materials selected from the group consisting of may be used. Further, a mixture of two or more materials selected from the above materials may be used as a binder.
  • graphite As the conductive agent for the positive electrode 21 and the negative electrode 22, graphite, carbon black, conductive fiber, graphite fluoride, metal powder, conductive whisker, conductive metal oxide, organic conductive material, or the like can be used.
  • graphite include natural graphite and artificial graphite.
  • carbon black include acetylene black, Ketjen black (registered trademark), channel black, furnace black, lamp black, and thermal black.
  • An example of a metal powder is aluminum powder.
  • conductive whiskers include zinc oxide whiskers and potassium titanate whiskers.
  • conductive metal oxides include titanium oxide.
  • organic conductive materials include phenylene derivatives.
  • the surface of the above-mentioned binder may be coated with a material that can be used as the above-mentioned conductive agent.
  • the above-mentioned binder may be coated on the surface with carbon black. Thereby, the capacity of the battery can be improved.
  • the separator 14 a material having a large ion permeability and sufficient mechanical strength can be used. Examples of such materials include microporous thin films, woven fabrics, non-woven fabrics, and the like. Specifically, it is desirable that the separator 14 is made of a polyolefin such as polypropylene or polyethylene. The separator 14 made of polyolefin not only has excellent durability, but can also exhibit a shutdown function when overheated. The thickness of the separator 14 is, for example, in the range of 10 to 300 ⁇ m (or 10 to 40 ⁇ m). The separator 14 may be a monolayer film made of one kind of material. Alternatively, the separator 14 may be a composite film (or a multilayer film) composed of two or more kinds of materials.
  • a polyolefin such as polypropylene or polyethylene.
  • the separator 14 made of polyolefin not only has excellent durability, but can also exhibit a shutdown function when overheated.
  • the thickness of the separator 14 is, for example
  • the porosity of the separator 14 is, for example, in the range of 30-70% (or 35-60%).
  • the “vacancy ratio” means the ratio of the volume of the pores to the total volume of the separator 14.
  • the "vacancy rate” is measured, for example, by the mercury intrusion method.
  • the non-aqueous electrolyte solution contains a non-aqueous solvent and a lithium salt dissolved in the non-aqueous solvent.
  • a cyclic carbonate solvent a chain carbonate solvent, a cyclic ether solvent, a chain ether solvent, a cyclic ester solvent, a chain ester solvent, a fluorine solvent, or the like can be used.
  • cyclic carbonate solvent examples include ethylene carbonate, propylene carbonate, butylene carbonate, and the like.
  • chain carbonate ester solvent examples include dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, and the like.
  • cyclic ether solvent examples include tetrahydrofuran, 1,4-dioxane, 1,3-dioxolane, and the like.
  • chain ether solvent examples include 1,2-dimethoxyethane, 1,2-diethoxyethane, and the like.
  • cyclic ester solvent examples include ⁇ -butyrolactone and the like.
  • chain ester solvent examples include methyl acetate, and the like.
  • fluorine solvent examples include fluoroethylene carbonate, methyl fluoropropionate, fluorobenzene, fluoroethyl methyl carbonate, fluorodimethylene carbonate, and the like.
  • non-aqueous solvent one kind of non-aqueous solvent selected from these can be used alone.
  • non-aqueous solvent a combination of two or more non-aqueous solvents selected from these can be used.
  • the non-aqueous electrolytic solution may contain at least one fluorine solvent selected from the group consisting of fluoroethylene carbonate, methyl fluoropropionate, fluorobenzene, fluoroethyl methyl carbonate, and fluorodimethylene carbonate.
  • fluorine solvent selected from the group consisting of fluoroethylene carbonate, methyl fluoropropionate, fluorobenzene, fluoroethyl methyl carbonate, and fluorodimethylene carbonate.
  • the battery 10 can be operated stably.
  • the electrolyte may be a solid electrolyte.
  • an organic polymer solid electrolyte As the solid electrolyte, an organic polymer solid electrolyte, an oxide solid electrolyte, a sulfide solid electrolyte, etc. are used.
  • organic polymer solid electrolyte for example, a compound of a polymer compound and a lithium salt can be used.
  • the polymer compound may have an ethylene oxide structure.
  • ethylene oxide structure By having an ethylene oxide structure, a large amount of lithium salt can be contained, and the ionic conductivity can be further increased.
  • oxide solid electrolyte examples include a NASICON type solid electrolyte typified by LiTi 2 (PO 4 ) 3 and its element substituent, a (LaLi) TiO 3 type perovskite type solid electrolyte, Li 14 ZnGe 4 O 16 , Li. 4 SiO 4 , LiGeO 4 and LISION type solid electrolyte typified by its element substitution product, Li 7 La 3 Zr 2 O 12 and garnet type solid electrolyte typified by its element substitution product, Li 3 N and its H substitution product , Li 3 PO 4 and its N-substituted products, and the like can be used.
  • NASICON type solid electrolyte typified by LiTi 2 (PO 4 ) 3 and its element substituent
  • a (LaLi) TiO 3 type perovskite type solid electrolyte Li 14 ZnGe 4 O 16 , Li. 4 SiO 4 , LiGeO 4 and LISION type solid electrolyte
  • the sulfide solid electrolyte for example, Li 2 S-P 2 S 5, Li 2 S-SiS 2, Li 2 S-B 2 S 3, Li 2 S-GeS 2, Li 3.25 Ge 0.25 P 0.75 S 4, Li 10 GeP 2 S 12 , etc.
  • LiX (X: F, Cl, Br, I), MO y , Li x MO y (any of M: P, Si, Ge, B, Al, Ga, In) (x, y: Natural numbers) and the like may be added.
  • the sulfide solid electrolyte is particularly rich in moldability and high ionic conductivity. Therefore, by using a sulfide solid electrolyte as the solid electrolyte, a battery having a higher energy density can be realized.
  • Li 2 SP 2 S 5 has high electrochemical stability and higher ionic conductivity. Therefore, if Li 2 SP 2 S 5 is used as the solid electrolyte, a battery having a higher energy density can be realized.
  • the solid electrolyte layer may contain the above-mentioned non-aqueous electrolyte solution.
  • the solid electrolyte layer contains a non-aqueous electrolyte solution, it becomes easy to transfer lithium ions between the active material and the solid electrolyte. As a result, a battery with a higher energy density can be realized.
  • the solid electrolyte layer may contain a gel electrolyte, an ionic liquid, etc. in addition to the solid electrolyte.
  • a polymer material containing a non-aqueous electrolyte solution can be used.
  • a polymer material a polymer having polyethylene oxide, polyacrylic nitrile, polyvinylidene fluoride, and polymethyl methacrylate, or ethylene oxide bond may be used.
  • the cations that make up the ionic liquid are aliphatic quaternary salts such as tetraalkylammonium and tetraalkylphosphonium, pyrrolidiniums, morpholiniums, imidazoliniums, tetrahydropyrimidiniums, piperaziniums, piperidiniums and other fats. It may be a nitrogen-containing heterocyclic aromatic cation such as group cyclic ammonium, pyridiniums, or imidazoliums.
  • PF 6 constituting the ionic liquid -, BF 4 -, SbF 6 -, AsF 6 -, SO 3 CF 3 -, N (SO 2 CF 3) 2 -, N (SO 2 C 2 F 5) 2 -, N (SO 2 CF 3 ) (SO 2 C 4 F 9) -, C (SO 2 CF 3) 3 - , or the like.
  • the ionic liquid may contain a lithium salt.
  • the lithium salt LiPF 6, LiBF 4, LiSbF 6, LiAsF 6, LiSO 3 CF 3, LiN (SO 2 CF 3) 2, LiN (SO 2 C 2 F 5) 2, LiN (SO 2 CF 3) ( SO 2 C 4 F 9 ), LiC (SO 2 CF 3 ) 3 , etc. can be used.
  • the lithium salt one type of lithium salt selected from these can be used alone.
  • the lithium salt a mixture of two or more kinds of lithium salts selected from these can be used.
  • the concentration of lithium salt is, for example, in the range of 0.5 to 2 mol / liter.
  • the battery according to the second embodiment can be configured as a battery having various shapes such as a coin type, a cylindrical type, a square type, a sheet type, a button type, a flat type, and a laminated type.
  • the obtained raw material was dissolved in pure water so that the concentration of Mn + Co + Ni was 2 mol / L to obtain a solution containing Mn, Co, and Ni (that is, a solution containing a Me source). Also, in separate containers, the KHCO 3 so that the concentration of KHCO 3 is 2 mol / L was dissolved in purified water to give a KHCO 3 solution.
  • Each was weighed so as to have a molar ratio of 1.
  • Powder X-ray diffraction measurement was performed on the obtained positive electrode active material.
  • the obtained positive electrode active material had a crystal structure belonging to the space group C2 / m.
  • the average composition of the lithium composite oxide of Example 1 determined from the molar ratio of the raw materials is represented by Li 1.2 Mn 0.54 Co 0.13 Ni 0.13 O 1.9 F 0.1 .
  • FIG. 3A is a STEM cross-sectional image of the lithium composite oxide particles of Example 1.
  • FIG. 3B is an atomic resolution image of the region 30 portion shown in FIG. 3A.
  • the lithium composite oxide particles of Example 1 contained a plurality of columnar crystal aggregates arranged radially from the center of the particles toward the surface. .. Further, from the atomic resolution image of FIG. 3B, in the crystalline crystal aggregate, the c-axis of the crystal structure is oriented in the major axis direction of the crystal aggregate, and the a-axis of the crystal structure is oriented in the minor axis direction of the crystal aggregate. It was confirmed that it was done.
  • a positive electrode mixture slurry was applied to one side of a positive electrode current collector formed of an aluminum foil having a thickness of 20 ⁇ m.
  • a positive electrode was obtained by punching the obtained positive electrode plate into a circular shape with a diameter of 12.5 mm.
  • a negative electrode was obtained by punching a lithium metal foil having a thickness of 300 ⁇ m into a circular shape having a diameter of 14.0 mm.
  • FEC fluoroethylene carbonate
  • EC ethylene carbonate
  • EMC ethyl methyl carbonate
  • a non-aqueous electrolytic solution was obtained by dissolving LiPF 6 in this non-aqueous solvent at a concentration of 1.0 mol / liter.
  • the obtained non-aqueous electrolytic solution was impregnated into a separator (manufactured by Celgard, product number 2320, thickness 25 ⁇ m).
  • the separator is a three-layer separator formed of a polypropylene layer, a polyethylene layer, and a polypropylene layer.
  • a CR2032 standard coin-type battery was manufactured in a dry box with a dew point controlled at ⁇ 50 ° C.
  • Example 2 to 7 From Example 1 described above, the mixing ratio of the raw materials to be subjected to the reaction was changed. Further, from Example 1 described above, the heat treatment conditions were changed within the range of 500 to 900 ° C. and 10 minutes to 10 hours. Except for these, the positive electrode active materials of Examples 2 to 7 were synthesized in the same manner as in Example 1 described above. Table 1 shows the average composition of the lithium composite oxide which is the positive electrode active material of Examples 2 to 7. In addition, Table 1 also shows the heat treatment temperature and heat treatment time.
  • the powder X-ray diffraction measurement was also carried out on the positive electrode active materials obtained in Examples 2 to 7 in the same manner as in Example 1. As shown in Table 1, the positive electrode active materials of Examples 2 to 7 had a crystal structure belonging to the space group C2 / m or R-3m.
  • Each was weighed so as to have a molar ratio of 1.
  • Powder X-ray diffraction measurement was performed on the obtained positive electrode active material.
  • the space group of the obtained positive electrode active material was C2 / m.
  • FIG. 4 is an SEM cross-sectional image of the lithium composite oxide particles of Comparative Example 1.
  • the lithium composite oxide particles of Comparative Example 1 did not contain columnar crystal aggregates arranged radially from the center of the particles toward the surface.
  • the positive electrode active materials obtained in Comparative Examples 2 and 3 were also subjected to powder X-ray diffraction measurement in the same manner as in Comparative Example 1. As shown in Table 1, the positive electrode active materials of Comparative Examples 2 and 3 had a crystal structure belonging to the space group C2 / m.
  • the discharge end voltage was set to 2.5 V, and the battery of Example 1 was discharged at a current density of 0.5 mA / cm 2 .
  • the initial discharge capacity of the battery of Example 1 was 283 mAh / g.
  • the initial discharge capacity of the coin-type batteries of Examples 2 to 7 and Comparative Examples 1 to 3 was measured by the same method as in Example 1.
  • Table 1 the initial discharge capacities of the batteries of Examples 1, 5, and 7, respectively, are larger than the initial discharge capacities of the batteries of Comparative Examples 1, 2, and 3, respectively.
  • the reason for this is that in the positive electrode active materials of Examples 1, 5, and 7, unlike Comparative Examples 1, 2, and 3, columnar crystal aggregates are formed in the particles of the lithium composite oxide. It is considered that this is because the a-axis is oriented in the minor axis direction of the crystal aggregate and the c-axis is oriented in the major axis direction of the crystal aggregate.
  • the positive electrode active materials of Examples 1, 5 and 7 having such a structure shortens the diffusion distance of Li ions and lowers the resistance during charging and discharging. Therefore, although the lithium composite oxide having the same composition is used as the positive electrode active material, the batteries of Examples 1, 5, and 7 are more than the batteries of Comparative Examples 1, 2, and 3. However, it is considered that the initial discharge capacity is large for each.
  • the initial discharge capacity of the battery of Example 1 is larger than the initial discharge capacity of the battery of Example 2.
  • the reason for this is that the positive electrode active material of Example 1 has more Co that contributes to the stabilization of the structure as compared with the positive electrode active material of Example 2. Therefore, in the positive electrode active material of Example 1, the structure during charging and discharging is stabilized. Therefore, it is considered that the initial discharge capacity of the battery of Example 1 is larger than that of the battery of Example 2.
  • the initial discharge capacity of the battery of Example 1 is larger than the initial discharge capacity of the battery of Example 3.
  • the positive electrode active material of Example 1 has a large amount of Ni having a valence of + II as compared with the positive electrode active material of Example 3. Therefore, in the battery of Example 1, the valence of Co in the positive electrode active material is unlikely to change from a stable +III to a low valence, and the positive electrode active material is stabilized. Therefore, it is considered that the initial discharge capacity of the battery of Example 1 is larger than that of the battery of Example 3.
  • the initial discharge capacity of the battery of Example 1 is larger than the initial discharge capacity of the battery of Example 4.
  • the positive electrode active material of Example 1 contains more electrochemically active Co and Ni than the positive electrode active material of Example 4. Therefore, in the battery of Example 1, it is considered that the redox amount of the transition metal increased during charging and discharging, and the initial discharging capacity increased.
  • the initial discharge capacity of the battery of Example 1 is larger than the initial discharge capacity of the battery of Example 5.
  • the positive electrode active material of Example 1 has a larger x / y value in the composition formula of the lithium composite oxide than the positive electrode active material of Example 4. Therefore, in the battery of Example 1, it is considered that the amount of Li that can contribute to the reaction increases, and the amount of Li inserted and removed during charging and discharging increases.
  • the initial discharge capacity of the battery of Example 5 is larger than the initial discharge capacity of the battery of Example 6.
  • the positive electrode active material of Example 5 has a larger amount of Co that contributes to structural stabilization than the positive electrode active material of Example 6. Therefore, in the positive electrode active material of Example 5, the structure during charging and discharging is stabilized. Therefore, it is considered that the initial discharge capacity of the battery of Example 5 is larger than that of the battery of Example 6.
  • the initial discharge capacity of the battery of Example 1 is larger than the initial discharge capacity of the battery of Example 7.
  • the positive electrode active material of Example 1 has a higher valence of the initial transition metal than the positive electrode active material of Example 7. Therefore, it is considered that the positive electrode active material of Example 1 does not have an excessively large amount of oxygen charge compensation during charging, and the structure during charging is stabilized. Therefore, it is considered that the initial discharge capacity of the battery of Example 1 is larger than that of the battery of Example 7.
  • the positive electrode active material of the present disclosure can be used as a positive electrode active material of a battery such as a secondary battery.

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Abstract

This positive electrode active material contains particles (1) of lithium composite oxide having a crystalline structure that belongs to a layered structure. The particles (1) contain a plurality of columnar crystal aggregates (2) which are aligned in a radial direction from the center to the surface of the particles (1). In the columnar crystal aggregates (2), the c axis of the crystalline structure is aligned in the major principal axis direction (3) of the crystal aggregates (2), and the a axis of the crystal structure is aligned in the minor principal axis direction (4) of the crystal aggregates (2).

Description

正極活物質、および、電池Positive electrode active material and battery
　本開示は、電池用の正極活物質、および、電池に関する。 The present disclosure relates to a positive electrode active material for a battery and a battery.
　特許文献１には、二次電池用正極活物質が開示されている。この正極活物質は、コア；前記コアを取り囲んで位置するシェル；および、前記コアとシェルの間に位置し、前記コアとシェルを連結する３次元網目構造体および空隙を含む緩衝層を含む。前記コア、シェル、および緩衝層での３次元網目構造体は、それぞれ独立して複数個の結晶粒を含む、化学式ＬｉaＮｉ1-x-yＣｏxＭ１yＭ３zＭ２wＯ2で表される多結晶リチウム複合金属酸化物を含む。前記結晶粒は、平均結晶サイズが５０ｎｍから１５０ｎｍである。ここで、特許文献１では、上記化学式において、Ｍ１は、ＡｌおよびＭｎからなる群より選択されるいずれか一つまたは二つ以上の元素を含む。Ｍ２は、Ｚｒ、Ｔｉ、Ｍｇ、ＴａおよびＮｂからなる群より選択されるいずれか一つまたは二つ以上の元素を含む。Ｍ３は、Ｗ、ＭｏおよびＣｒからなる群より選択されるいずれか一つまたは二つ以上の元素を含む。ａ、ｘ、ｙ、ｚ、およびｗは、１．０≦ａ≦１．５、０＜ｘ≦０．５、０＜ｙ≦０．５、０．０００５≦ｚ≦０．０３、０≦ｗ≦０．０２、０＜ｘ＋ｙ≦０．７を満たす。 Patent Document 1 discloses a positive electrode active material for a secondary battery. The positive electrode active material includes a core; a shell located surrounding the core; and a cushioning layer located between the core and the shell and containing a three-dimensional network structure connecting the core and the shell and voids. The three-dimensional network structure in the core, shell, and buffer layer is represented by the chemical formula Li a Ni 1-xy Co x M1 y M3 z M2 w O 2 , each containing a plurality of crystal grains independently. Contains polycrystalline lithium composite metal oxide. The crystal grains have an average crystal size of 50 nm to 150 nm. Here, in Patent Document 1, in the above chemical formula, M1 contains any one or more elements selected from the group consisting of Al and Mn. M2 comprises any one or more elements selected from the group consisting of Zr, Ti, Mg, Ta and Nb. M3 comprises any one or more elements selected from the group consisting of W, Mo and Cr. a, x, y, z, and w are 1.0 ≦ a ≦ 1.5, 0 <x ≦ 0.5, 0 <y ≦ 0.5, 0.0005 ≦ z ≦ 0.03, 0 ≦ Satisfy w ≦ 0.02 and 0 <x + y ≦ 0.7.
特表２０１８－５２１４５６号公報Special Table 2018-521456
　従来技術においては、高容量の電池の実現が望まれる。 In the conventional technology, it is desired to realize a high capacity battery.
　本開示の一様態における正極活物質は、層状構造に属する結晶構造を有するリチウム複合酸化物の粒子を含み、前記粒子は、当該粒子の中心から表面に向かって放射状に並んだ、複数の柱状の結晶集合体を含み、前記柱状の結晶集合体において、前記結晶構造のｃ軸が前記結晶集合体の長軸方向に配向し、かつ前記結晶構造のａ軸が前記結晶集合体の短軸方向に配向している。 The positive electrode active material in the uniform state of the present disclosure contains particles of a lithium composite oxide having a crystal structure belonging to a layered structure, and the particles are arranged radially from the center of the particles toward the surface, and a plurality of columns are arranged. In the columnar crystal aggregate including the crystal aggregate, the c-axis of the crystal structure is oriented in the major axis direction of the crystal aggregate, and the a-axis of the crystal structure is in the minor axis direction of the crystal aggregate. Oriented.
　本開示の包括的または具体的な態様は、電池用正極活物質、電池、方法、または、これらの任意な組み合わせで実現されてもよい。 Comprehensive or specific embodiments of the present disclosure may be realized by a positive electrode active material for a battery, a battery, a method, or any combination thereof.
　本開示によれば、高容量の電池を実現できる。 According to the present disclosure, a high capacity battery can be realized.
図１は、実施の形態１における正極活物質に含まれるリチウム複合酸化物の粒子の構造を説明するための、当該粒子の一部の構造モデルを示す図である。FIG. 1 is a diagram showing a structural model of a part of the particles for explaining the structure of the particles of the lithium composite oxide contained in the positive electrode active material in the first embodiment. 図２は、実施の形態２における電池の一例である電池１０の概略構成を示す断面図である。FIG. 2 is a cross-sectional view showing a schematic configuration of a battery 10 which is an example of the battery according to the second embodiment. 図３Ａは、実施例１のリチウム複合酸化物の粒子の、走査型透過電子顕微鏡（ＳＴＥＭ）断面像である。FIG. 3A is a scanning transmission electron microscope (STEM) cross-sectional image of the lithium composite oxide particles of Example 1. 図３Ｂは、図３Ａに示された領域３０部分の原子分解能像である。FIG. 3B is an atomic resolution image of the region 30 portion shown in FIG. 3A. 図４は、比較例１のリチウム複合酸化物の粒子の、走査型電子顕微鏡（ＳＥＭ）断面像である。FIG. 4 is a scanning electron microscope (SEM) cross-sectional image of the lithium composite oxide particles of Comparative Example 1.
　以下、本開示の実施の形態が、説明される。 Hereinafter, embodiments of the present disclosure will be described.
　（実施の形態１）
　実施の形態１における正極活物質は、層状構造に属する結晶構造を有するリチウム複合酸化物の粒子を含む。このリチウム複合酸化物の粒子は、当該粒子の中心から表面に向かって放射状に並んだ、複数の柱状の結晶集合体を含む。柱状の結晶集合体において、層状構造に属する上記結晶構造のｃ軸が結晶集合体の長軸方向に配向し、かつａ軸が結晶集合体の短軸方向に配向している。 (Embodiment 1)
The positive electrode active material in the first embodiment contains particles of a lithium composite oxide having a crystal structure belonging to a layered structure. The particles of the lithium composite oxide include a plurality of columnar crystal aggregates arranged radially from the center of the particles toward the surface. In the columnar crystal aggregate, the c-axis of the crystal structure belonging to the layered structure is oriented in the major axis direction of the crystal aggregate, and the a-axis is oriented in the minor axis direction of the crystal aggregate.
　ここで、柱状の結晶集合体は、層状構造に属する結晶構造を有する複数の結晶の集合体であって、この集合体の全体の形状が柱状である。上記のとおり、柱状の結晶集合体において、層状構造に属する結晶構造のｃ軸が結晶集合体の長軸方向に配向し、かつａ軸が結晶集合体の短軸方向に配向している。したがって、例えば、柱状の結晶集合体は、結晶方位が互いに一致している、層状構造に属する結晶構造を有する複数の結晶によって構成されている、ということもできる。 Here, the columnar crystal aggregate is an aggregate of a plurality of crystals having a crystal structure belonging to a layered structure, and the overall shape of this aggregate is columnar. As described above, in the columnar crystal aggregate, the c-axis of the crystal structure belonging to the layered structure is oriented in the major axis direction of the crystal aggregate, and the a-axis is oriented in the minor axis direction of the crystal aggregate. Therefore, for example, it can be said that a columnar crystal aggregate is composed of a plurality of crystals having a crystal structure belonging to a layered structure in which the crystal orientations coincide with each other.
　以上の構成によれば、高容量の電池を実現できる。 According to the above configuration, a high capacity battery can be realized.
　実施の形態１における正極活物質は、例えば、リチウムイオン電池用の正極活物質である。実施の形態１における正極活物質を用いて、例えばリチウムイオン電池を構成する場合、当該リチウムイオン電池は、３．４Ｖ程度の酸化還元電位（Ｌｉ／Ｌｉ+基準）を有する。また、当該リチウムイオン電池は、概ね、２６０ｍＡｈ／ｇ以上の容量を有する。 The positive electrode active material in the first embodiment is, for example, a positive electrode active material for a lithium ion battery. When, for example, a lithium ion battery is constructed by using the positive electrode active material in the first embodiment, the lithium ion battery has an oxidation-reduction potential (Li / Li + reference) of about 3.4 V. In addition, the lithium ion battery has a capacity of about 260 mAh / g or more.
　実施の形態１における正極活物質の構造について、図面を参照しながら、より具体的に説明する。図１は、実施の形態１における正極活物質に含まれるリチウム複合酸化物の粒子の構造を説明するための、当該粒子の一部の構造モデルを示す図である。 The structure of the positive electrode active material according to the first embodiment will be described more specifically with reference to the drawings. FIG. 1 is a diagram showing a structural model of a part of the particles for explaining the structure of the particles of the lithium composite oxide contained in the positive electrode active material in the first embodiment.
　図１に示すように、リチウム複合酸化物の粒子１は、複数の柱状の結晶集合体２を含む。粒子１において、複数の柱状の結晶集合体２は、粒子１の中心から表面に向かって放射状に並んでいる。例えば、結晶集合体２は、粒子１の中心から表面に向かって放射状に秩序立って並んでいてもよい。結晶集合体２は、粒子１の中心から表面に向かって放射状に配列していてもよい。上述のとおり、粒子１におけるリチウム複合酸化物は、層状構造に属する結晶構造を有する。したがって、柱状の結晶集合体２を構成する結晶は、層状構造に属する結晶構造を有する。このような結晶構造を有する結晶集合体２において、層状構造に属する結晶構造のｃ軸が結晶集合体２の長軸方向３に配向し、かつａ軸が結晶集合体２の短軸方向４に配向している。結晶集合体２がこのような配向を有する結晶で構成されていることにより、結晶集合体２では、短軸方向４に沿ってＬｉの拡散パスが形成される。 As shown in FIG. 1, the lithium composite oxide particle 1 contains a plurality of columnar crystal aggregates 2. In the particle 1, the plurality of columnar crystal aggregates 2 are arranged radially from the center of the particle 1 toward the surface. For example, the crystal aggregates 2 may be arranged in a radial order from the center of the particles 1 toward the surface. The crystal aggregates 2 may be arranged radially from the center of the particles 1 toward the surface. As described above, the lithium composite oxide in particle 1 has a crystal structure belonging to a layered structure. Therefore, the crystals constituting the columnar crystal aggregate 2 have a crystal structure belonging to the layered structure. In the crystal assembly 2 having such a crystal structure, the c-axis of the crystal structure belonging to the layered structure is oriented in the major axis direction 3 of the crystal assembly 2, and the a-axis is oriented in the minor axis direction 4 of the crystal assembly 2. It is oriented. Since the crystal aggregate 2 is composed of crystals having such an orientation, a diffusion path of Li is formed in the crystal aggregate 2 along the minor axis direction 4.
　上記の構成を有するリチウム複合酸化物の粒子１では、互いに隣り合う結晶集合体２の間の隙間を介して、Ｌｉが粒子内部まで容易に到達でき、またＬｉが粒子内部から粒子外へ容易に出ることができる。さらに、Ｌｉの拡散パスは短軸方向４に沿って形成されているので、正極活物質へＬｉが拡散する際のＬｉの移動距離が短い。このような理由により、リチウム複合酸化物の粒子１を含む正極活物質は、電池の容量および出力を向上させることができる。 In the lithium composite oxide particle 1 having the above structure, Li can easily reach the inside of the particle through the gap between the crystal aggregates 2 adjacent to each other, and Li can be easily reached from the inside of the particle to the outside of the particle. You can get out. Further, since the diffusion path of Li is formed along the minor axis direction 4, the moving distance of Li when the Li diffuses into the positive electrode active material is short. For this reason, the positive electrode active material containing the lithium composite oxide particles 1 can improve the capacity and output of the battery.
　ここで、比較形態として、例えば特許文献１に記載されている正極活物質について検討する。特許文献１に記載されている正極活物質は、コア部分、コア部分周囲に位置するシェル部分、およびコア部分とシェル部分との間隙に存在する緩衝層を有している。シェル部分は、正極活物質の中心から表面の方向に放射状に成長された結晶配向性の多結晶リチウム複合金属酸化物の粒子を含んでいる。しかし、特許文献１に記載されている正極活物質は、本開示の実施の形態１における正極活物質のような配向を有する結晶で構成された柱状の結晶集合体を含んでいない。すなわち、特許文献１に記載されている正極活物質では、ａ軸方向が短軸方向に平行で、かつｃ軸方向が長軸方向に平行となる結晶構造を有する結晶集合体が実現されておらず、そのような構造についての示唆もされていない。すなわち、実施の形態１における正極活物質に含まれるリチウム複合酸化物は、従来存在せず、さらに従来技術からは容易に到達できない構造を有している。これにより、実施の形態１における正極活物質は、高容量の電池を実現することができる。 Here, as a comparative form, for example, the positive electrode active material described in Patent Document 1 will be examined. The positive electrode active material described in Patent Document 1 has a core portion, a shell portion located around the core portion, and a buffer layer existing in a gap between the core portion and the shell portion. The shell portion contains particles of crystal-oriented polycrystalline lithium composite metal oxide grown radially from the center of the positive electrode active material toward the surface. However, the positive electrode active material described in Patent Document 1 does not include a columnar crystal aggregate composed of crystals having an orientation like the positive electrode active material in the first embodiment of the present disclosure. That is, in the positive electrode active material described in Patent Document 1, a crystal aggregate having a crystal structure in which the a-axis direction is parallel to the minor axis direction and the c-axis direction is parallel to the major axis direction has been realized. No suggestion is made for such a structure. That is, the lithium composite oxide contained in the positive electrode active material according to the first embodiment does not exist in the past and has a structure that cannot be easily reached from the prior art. As a result, the positive electrode active material in the first embodiment can realize a high-capacity battery.
　実施の形態１における正極活物質において、柱状の結晶集合体の短軸の長さをＸｎｍとすると、Ｘは、１０＜Ｘ＜５００を満たしてもよい。ここで、柱状の結晶集合体の短軸の長さとは、短軸方向における柱状の結晶集合体の最大長さを意味する。短軸方向における柱状の結晶集合体の最大長さとは、すなわち、リチウム複合酸化物の粒子の表面付近における、柱状の結晶集合体の短軸方向の長さに相当する。この構成によれば、Ｌｉが拡散する距離が短くなる。このため、より高容量の電池を実現できる。 In the positive electrode active material according to the first embodiment, assuming that the length of the minor axis of the columnar crystal aggregate is X nm, X may satisfy 10 <X <500. Here, the length of the minor axis of the columnar crystal aggregate means the maximum length of the columnar crystal aggregate in the minor axis direction. The maximum length of the columnar crystal aggregate in the minor axis direction corresponds to the length in the minor axis direction of the columnar crystal aggregate in the vicinity of the surface of the lithium composite oxide particles. According to this configuration, the distance at which Li diffuses becomes short. Therefore, a higher capacity battery can be realized.
　また、Ｘは、２０＜Ｘ＜２５０を満たしてもよい。この構成によれば、Ｌｉが拡散する距離が短くなる。このため、より高容量の電池を実現できる。 Further, X may satisfy 20 <X <250. According to this configuration, the distance at which Li diffuses becomes short. Therefore, a higher capacity battery can be realized.
　実施の形態１における正極活物質において、柱状の結晶集合体の長軸の長さをＹμｍとすると、Ｙは、１＜Ｙ＜１５を満たしてもよい。柱状の結晶集合体の長軸の長さは、例えば、リチウム複合酸化物の粒子の半径に相当してもよい。 In the positive electrode active material according to the first embodiment, if the length of the long axis of the columnar crystal aggregate is Y μm, Y may satisfy 1 <Y <15. The length of the major axis of the columnar crystal aggregate may correspond to, for example, the radius of the particles of the lithium composite oxide.
　実施の形態１における正極活物質において、リチウム複合酸化物の粒子は、上述のとおり、層状構造に属する結晶構造を有する。この層状構造に属する結晶構造は、空間群Ｃ２／ｍおよび空間群Ｒ－３ｍからなる群より選択される少なくとも１つに属していてもよい。この層状構造に属する結晶構造が、空間群Ｃ２／ｍに属する相と、空間群Ｒ－３ｍに属する相との両方を含む混相であってもよい。この構成によれば、Ｌｉの拡散性がさらに向上するため、より高容量の電池を実現できる。 In the positive electrode active material of the first embodiment, the lithium composite oxide particles have a crystal structure belonging to the layered structure as described above. The crystal structure belonging to this layered structure may belong to at least one selected from the group consisting of the space group C2 / m and the space group R-3m. The crystal structure belonging to this layered structure may be a mixed phase including both a phase belonging to the space group C2 / m and a phase belonging to the space group R-3m. According to this configuration, the diffusibility of Li is further improved, so that a battery having a higher capacity can be realized.
　空間群Ｃ２／ｍに属する結晶構造は、Ｌｉ層と遷移金属層（「遷移金属等のカチオン元素」が占める層）とが交互に積層した構造を有する。また、遷移金属層には、「遷移金属等のカチオン元素」以外に、Ｌｉを含有することができる。そのため、空間群Ｃ２／ｍに属する結晶構造は、一般的な従来材料であるＬｉＣｏＯ2よりも、より多くのＬｉを結晶構造内に吸蔵することができる。 The crystal structure belonging to the space group C2 / m has a structure in which Li layers and transition metal layers (layers occupied by "cation elements such as transition metals") are alternately laminated. Further, the transition metal layer can contain Li in addition to "cationic elements such as transition metals". Therefore, the crystal structure belonging to the space group C2 / m can occlude more Li in the crystal structure than the general conventional material LiCoO 2 .
　一方、空間群Ｒ－３ｍに属する結晶構造も、Ｌｉ層と遷移金属層とが交互に積層した構造を有する。空間群Ｒ－３ｍに属する結晶構造は、二次元的にＬｉの拡散経路が存在するため、Ｌｉの拡散性が高い。 On the other hand, the crystal structure belonging to the space group R-3m also has a structure in which Li layers and transition metal layers are alternately laminated. The crystal structure belonging to the space group R-3m has a high diffusion property of Li because the diffusion path of Li exists two-dimensionally.
　実施の形態１における正極活物質のリチウム複合酸化物の結晶構造が属する空間群は、例えば、Ｘ線回折（Ｘ－ｒａｙ　ｄｉｆｆｒａｃｔｉｏｎ：ＸＲＤ）測定または電子線回折測定によって特定されうる。 The space group to which the crystal structure of the lithium composite oxide of the positive electrode active material in the first embodiment belongs can be specified by, for example, X-ray diffraction (XRD) measurement or electron beam diffraction measurement.
　実施の形態１における正極活物質において、リチウム複合酸化物の粒子は、内部に空隙層を有していてもよい。この構成によれば、例えば電解液が粒子と触れる面積が大きくなり、粒子内へのＬｉの拡散性がさらに向上する。これにより、より高容量の電池を実現できる。リチウム複合酸化物の粒子が空隙層を有する場合、例えば、空隙層よりも内側部分を粒子のコア部とみなし、空隙層よりも外側部分を粒子のシェル部とみなしてもよい。なお、リチウム複合酸化物の粒子は、複数の空隙層を有していてもよい。リチウム複合酸化物の粒子が複数の空隙層を有する場合、最も大きい厚さを有する空隙層よりも内側部分をコア部、外側部分をシェル部とみなしてもよい。 In the positive electrode active material according to the first embodiment, the lithium composite oxide particles may have a void layer inside. According to this configuration, for example, the area where the electrolytic solution comes into contact with the particles becomes large, and the diffusibility of Li into the particles is further improved. As a result, a battery with a higher capacity can be realized. When the particles of the lithium composite oxide have a void layer, for example, the portion inside the void layer may be regarded as the core portion of the particles, and the portion outside the void layer may be regarded as the shell portion of the particles. The lithium composite oxide particles may have a plurality of void layers. When the lithium composite oxide particles have a plurality of void layers, the inner portion of the void layer having the largest thickness may be regarded as the core portion and the outer portion may be regarded as the shell portion.
　また、実施の形態１における正極活物質において、リチウム複合酸化物は、Ｆ、Ｃｌ、Ｎ、およびＳからなる群より選択される少なくとも１種を含んでいてもよい。 Further, in the positive electrode active material according to the first embodiment, the lithium composite oxide may contain at least one selected from the group consisting of F, Cl, N, and S.
　以上の構成によれば、電気化学的に不活性なアニオンによって酸素の一部を置換することで、結晶構造が安定化すると考えられる。また、イオン半径の大きなアニオンによって酸素の一部を置換することで、結晶格子が広がり、Ｌｉの拡散性が向上すると考えられる。このため、より多くのＬｉを挿入および脱離させることが可能になると考えられる。このため、高容量の電池を実現できる。 According to the above configuration, it is considered that the crystal structure is stabilized by substituting a part of oxygen with an electrochemically inactive anion. Further, it is considered that the crystal lattice is expanded and the diffusibility of Li is improved by substituting a part of oxygen with an anion having a large ionic radius. Therefore, it is considered that more Li can be inserted and removed. Therefore, a high-capacity battery can be realized.
　また、例えば、実施の形態１における正極活物質において、リチウム複合酸化物が、Ｆ、Ｃｌ、Ｎ、およびＳからなる群より選択される少なくとも１種の元素を含む場合、酸素のレドックス量が多くなりすぎない。このため、酸素脱離によって結晶構造が不安定になることが抑制されるので、容量またはサイクル特性が向上すると考えられる。 Further, for example, in the positive electrode active material according to the first embodiment, when the lithium composite oxide contains at least one element selected from the group consisting of F, Cl, N, and S, the amount of oxygen redox is large. Not too much. Therefore, it is considered that the capacity or cycle characteristics are improved because the crystal structure is suppressed from becoming unstable due to oxygen desorption.
　また、実施の形態１における正極活物質において、リチウム複合酸化物は、Ｆを含んでもよい。 Further, in the positive electrode active material according to the first embodiment, the lithium composite oxide may contain F.
　以上の構成によれば、電気陰性度が高いＦによって酸素の一部を置換することで、カチオン－アニオンの相互作用が増加し、電池の放電容量または作動電圧が向上する。また、電気陰性度の高いＦを固溶させることで、Ｆを含まない場合と比較して電子が局在化する。このため、充電時における酸素脱離を抑制することができるため、結晶構造が安定化する。このため、より多くのＬｉを挿入および脱離させることが可能になると考えられる。これらの効果が総合的に作用することで、より高容量の電池を実現できると考えられる。 According to the above configuration, by substituting a part of oxygen with F having a high electronegativity, the interaction between cation and anion is increased, and the discharge capacity or operating voltage of the battery is improved. Further, by dissolving F having a high electronegativity as a solid solution, electrons are localized as compared with the case where F is not contained. Therefore, oxygen desorption during charging can be suppressed, and the crystal structure is stabilized. Therefore, it is considered that more Li can be inserted and removed. It is considered that a battery with a higher capacity can be realized by the comprehensive action of these effects.
　また、実施の形態１における正極活物質において、リチウム複合酸化物は、リチウム以外の「遷移金属等のカチオン元素」として、例えば、Ｍｎ、Ｃｏ、Ｎｉ、Ｆｅ、Ｃｕ、Ｖ、Ｎｂ、Ｍｏ、Ｔｉ、Ｃｒ、Ｚｒ、Ｚｎ、Ｎａ、Ｋ、Ｃａ、Ｍｇ、Ｐｔ、Ａｕ、Ａｇ、Ｒｕ、Ｗ、Ｂ、Ｓｉ、Ｐ、およびＡｌからなる群より選択される少なくとも１種を含んでいてもよい。 Further, in the positive electrode active material according to the first embodiment, the lithium composite oxide is a "cationic element such as a transition metal" other than lithium, for example, Mn, Co, Ni, Fe, Cu, V, Nb, Mo, Ti. , Cr, Zr, Zn, Na, K, Ca, Mg, Pt, Au, Ag, Ru, W, B, Si, P, and Al, which may contain at least one selected from the group.
　また、実施の形態１における正極活物質において、リチウム複合酸化物は、上述の「遷移金属等のカチオン元素」として、例えば、Ｍｎ、Ｃｏ、Ｎｉ、Ｆｅ、Ｃｕ、Ｖ、Ｔｉ、Ｃｒ、およびＺｎからなる群より選択される少なくとも１種、すなわち、少なくとも１種の３ｄ遷移金属元素を含んでもよい。 Further, in the positive electrode active material according to the first embodiment, the lithium composite oxide is, for example, Mn, Co, Ni, Fe, Cu, V, Ti, Cr, and Zn as the above-mentioned "cation elements such as transition metals". It may contain at least one selected from the group consisting of, i.e., at least one 3d transition metal element.
　以上の構成によれば、より高容量の電池を実現できる。 According to the above configuration, a higher capacity battery can be realized.
　また、実施の形態１における正極活物質において、リチウム複合酸化物は、上述の「遷移金属等のカチオン元素」として、例えば、Ｍｎ、Ｃｏ、Ｎｉ、およびＡｌからなる群より選択される少なくとも１種を含んでもよい。 Further, in the positive electrode active material according to the first embodiment, the lithium composite oxide is at least one selected from the group consisting of, for example, Mn, Co, Ni, and Al as the above-mentioned "cationic element such as a transition metal". May include.
　以上の構成によれば、より高容量の電池を実現できる。 According to the above configuration, a higher capacity battery can be realized.
　また、実施の形態１における正極活物質において、リチウム複合酸化物は、Ｍｎを含んでもよい。 Further, in the positive electrode active material according to the first embodiment, the lithium composite oxide may contain Mn.
　以上の構成によれば、酸素と軌道混成しやすいＭｎを含むことで、充電時における酸素脱離が抑制される。このため、より多くのＬｉを挿入および脱離させることが可能になると考えられる。このため、より高容量の電池を実現できる。 According to the above configuration, oxygen desorption during charging is suppressed by containing Mn, which easily hybridizes with oxygen. Therefore, it is considered that more Li can be inserted and removed. Therefore, a higher capacity battery can be realized.
　次に、実施の形態１における正極活物質において、リチウム複合酸化物の化学組成の一例を説明する。 Next, an example of the chemical composition of the lithium composite oxide in the positive electrode active material according to the first embodiment will be described.
　実施の形態１における正極活物質において、リチウム複合酸化物の平均組成は、下記の組成式（１）で表されてもよい。
　ＬｉxＭｅyＯαＱβ　・・・式（１） In the positive electrode active material according to the first embodiment, the average composition of the lithium composite oxide may be represented by the following composition formula (1).
Li x Me y O α Q β ··· formula (1)
　ここで、Ｍｅは、Ｍｎ、Ｃｏ、Ｎｉ、Ｆｅ、Ｃｕ、Ｖ、Ｎｂ、Ｍｏ、Ｔｉ、Ｃｒ、Ｚｒ、Ｚｎ、Ｎａ、Ｋ、Ｃａ、Ｍｇ、Ｐｔ、Ａｕ、Ａｇ、Ｒｕ、Ｗ、Ｂ、Ｓｉ、Ｐ、およびＡｌからなる群より選択される少なくとも１種であってもよい。 Here, Me is Mn, Co, Ni, Fe, Cu, V, Nb, Mo, Ti, Cr, Zr, Zn, Na, K, Ca, Mg, Pt, Au, Ag, Ru, W, B, It may be at least one selected from the group consisting of Si, P, and Al.
　また、Ｑは、Ｆ、Ｃｌ、Ｎ、およびＳからなる群より選択される少なくとも１種であってもよい。 Further, Q may be at least one selected from the group consisting of F, Cl, N, and S.
　組成式（１）は、下記の条件、
１．０５≦ｘ≦１．５、
０．６≦ｙ≦１．０、
１．２≦α≦２．０、および
０＜β≦０．８、
を満たしてもよい。 The composition formula (1) is based on the following conditions.
1.05 ≤ x ≤ 1.5,
0.6 ≤ y ≤ 1.0,
1.2 ≤ α ≤ 2.0, and 0 <β ≤ 0.8,
May be satisfied.
　以上の構成によれば、より高容量の電池を実現できる。 According to the above configuration, a higher capacity battery can be realized.
　なお、実施の形態１においては、Ｍｅが２種以上の元素（例えば、Ｍｅ’、Ｍｅ”）からなり、かつ、組成比が「Ｍｅ’y1Ｍｅ”y2」である場合には、「ｙ＝ｙ１＋ｙ２」である。例えば、Ｍｅが２種の元素（ＭｎおよびＣｏ）からなり、かつ、組成比が「Ｍｎ0.6Ｃｏ0.2」である場合には、「ｙ＝０．６＋０．２＝０．８」である。また、Ｑが２種以上の元素からなる場合についても、Ｍｅの場合と同様に計算できる。 In the first embodiment, when Me is composed of two or more kinds of elements (for example, Me', Me ") and the composition ratio is"Me'y1 Me " y2 ", "y =". y1 + y2 ”. For example, when Me is composed of two kinds of elements (Mn and Co) and the composition ratio is "Mn 0.6 Co 0.2 ", it is "y = 0.6 + 0.2 = 0.8". Further, the case where Q is composed of two or more kinds of elements can be calculated in the same manner as in the case of Me.
　なお、組成式（１）において、ｘが１．０５以上の場合、利用できるＬｉ量が多くなる。このため、容量が向上する。 In the composition formula (1), when x is 1.05 or more, the amount of Li that can be used increases. Therefore, the capacity is improved.
　また、組成式（１）において、ｘが１．５以下の場合、利用できるＭｅの酸化還元反応が多くなる。この結果、酸素の酸化還元反応を多く利用する必要がなくなる。これにより、結晶構造が安定化する。このため、容量が向上する。 Further, in the composition formula (1), when x is 1.5 or less, the redox reaction of Me that can be used increases. As a result, it is not necessary to utilize a lot of oxygen redox reactions. This stabilizes the crystal structure. Therefore, the capacity is improved.
　また、組成式（１）において、ｙが０．６以上の場合、利用できるＭｅの酸化還元反応が多くなる。この結果、酸素の酸化還元反応を多く利用する必要がなくなる。これにより、結晶構造が安定化する。このため、容量が向上する。 Further, in the composition formula (1), when y is 0.6 or more, the redox reaction of Me that can be used increases. As a result, it is not necessary to utilize a lot of oxygen redox reactions. This stabilizes the crystal structure. Therefore, the capacity is improved.
　また、組成式（１）において、ｙが１．０以下の場合、利用できるＬｉ量が多くなる。このため、容量が向上する。 Further, in the composition formula (1), when y is 1.0 or less, the amount of Li that can be used increases. Therefore, the capacity is improved.
　また、組成式（１）において、αが１．２以上の場合、酸素の酸化還元による電荷補償量が低下することを防ぐことができる。このため、容量が向上する。 Further, in the composition formula (1), when α is 1.2 or more, it is possible to prevent the charge compensation amount due to the redox of oxygen from decreasing. Therefore, the capacity is improved.
　また、組成式（１）において、αが２．０以下の場合、酸素の酸化還元による容量が過剰となることを防ぐことができ、Ｌｉが脱離した際に構造が安定化する。このため、容量が向上する。 Further, in the composition formula (1), when α is 2.0 or less, it is possible to prevent the capacity due to redox of oxygen from becoming excessive, and the structure is stabilized when Li is eliminated. Therefore, the capacity is improved.
　また、組成式（１）において、βが０よりも大きい場合、電気化学的に不活性なＱの影響により、Ｌｉが脱離した際に構造が安定化する。このため、容量が向上する。 Further, in the composition formula (1), when β is larger than 0, the structure is stabilized when Li is eliminated due to the influence of the electrochemically inactive Q. Therefore, the capacity is improved.
　また、組成式（１）において、βが０．８以下の場合、電気化学的に不活性なＱの影響が大きくなることを防ぐことができるため、電子伝導性が向上する。このため、容量が向上する。 Further, in the composition formula (1), when β is 0.8 or less, it is possible to prevent the influence of the electrochemically inactive Q from becoming large, so that the electron conductivity is improved. Therefore, the capacity is improved.
　なお、実施の形態１におけるリチウム複合酸化物の「平均組成」とは、リチウム複合酸化物に対して各相の組成の違いを考慮せずに元素分析を行なうことによって得られる組成である。典型的には、リチウム複合酸化物の一次粒子のサイズと同程度、または、それよりも大きな試料を用いて元素分析を行なうことによって得られる組成を意味する。 The "average composition" of the lithium composite oxide in the first embodiment is a composition obtained by performing elemental analysis on the lithium composite oxide without considering the difference in the composition of each phase. Typically, it means the composition obtained by performing elemental analysis using a sample as large as or larger than the size of the primary particles of the lithium composite oxide.
　なお、上述の平均組成は、ＩＣＰ発光分光分析法、不活性ガス溶融－赤外線吸収法、イオンクロマトグラフィー、またはそれら分析方法の組み合わせにより決定することができる。 The above-mentioned average composition can be determined by ICP emission spectroscopy, inert gas melting-infrared absorption method, ion chromatography, or a combination of these analysis methods.
　また、組成式（１）において、Ｍｅは、Ｍｎ、Ｃｏ、Ｎｉ、Ｆｅ、Ｃｕ、Ｖ、Ｔｉ、Ｃｒ、およびＺｎからなる群より選択される少なくとも１種、すなわち、少なくとも１種の３ｄ遷移金属元素を含んでもよい。 Further, in the composition formula (1), Me is at least one selected from the group consisting of Mn, Co, Ni, Fe, Cu, V, Ti, Cr, and Zn, that is, at least one 3d transition metal. It may contain elements.
　以上の構成によれば、より高容量の電池を実現できる。 According to the above configuration, a higher capacity battery can be realized.
　また、組成式（１）において、Ｍｅは、Ｍｎ、Ｃｏ、Ｎｉ、およびＡｌからなる群より選択される少なくとも１種を含んでもよい。 Further, in the composition formula (1), Me may contain at least one selected from the group consisting of Mn, Co, Ni, and Al.
　以上の構成によれば、より高容量の電池を実現できる。 According to the above configuration, a higher capacity battery can be realized.
　また、組成式（１）において、Ｍｅは、Ｍｎを含んでもよい。 Further, in the composition formula (1), Me may contain Mn.
　すなわち、Ｍｅは、Ｍｎであってもよい。 That is, Me may be Mn.
　もしくは、Ｍｅは、Ｃｏ、Ｎｉ、Ｆｅ、Ｃｕ、Ｖ、Ｎｂ、Ｍｏ、Ｔｉ、Ｃｒ、Ｚｒ、Ｚｎ、Ｎａ、Ｋ、Ｃａ、Ｍｇ、Ｐｔ、Ａｕ、Ａｇ、Ｒｕ、Ｗ、Ｂ、Ｓｉ、Ｐ、およびＡｌからなる群より選択される少なくとも１種の元素と、Ｍｎとを、含んでもよい。 Alternatively, Me is Co, Ni, Fe, Cu, V, Nb, Mo, Ti, Cr, Zr, Zn, Na, K, Ca, Mg, Pt, Au, Ag, Ru, W, B, Si, P. , And at least one element selected from the group consisting of Al, and Mn may be contained.
　以上の構成によれば、酸素と軌道混成しやすいＭｎを含むことで、充電時における酸素脱離が抑制される。このため、より高容量の電池を実現できる。 According to the above configuration, oxygen desorption during charging is suppressed by containing Mn, which easily hybridizes with oxygen. Therefore, a higher capacity battery can be realized.
　また、組成式（１）において、Ｍｅに対するＭｎの割合が、５９．９モル％以上であってもよい。すなわち、Ｍｎを含むＭｅ全体に対する、Ｍｎのｍｏｌ比（Ｍｎ／Ｍｅ比）が、０．５９９～１．０の関係を満たしてもよい。 Further, in the composition formula (1), the ratio of Mn to Me may be 59.9 mol% or more. That is, the mol ratio (Mn / Me ratio) of Mn to the entire Me containing Mn may satisfy the relationship of 0.599 to 1.0.
　以上の構成によれば、酸素と軌道混成しやすいＭｎを多く含むことで、充電時における酸素脱離がさらに抑制される。このため、より高容量の電池を実現できる。 According to the above configuration, oxygen desorption during charging is further suppressed by containing a large amount of Mn, which easily hybridizes with oxygen. Therefore, a higher capacity battery can be realized.
　また、組成式（１）において、Ｍｅは、Ｂ、Ｓｉ、Ｐ、およびＡｌからなる群より選択される少なくとも１種を、Ｍｅに対して２０モル％以下含んでもよい。 Further, in the composition formula (1), Me may contain at least one selected from the group consisting of B, Si, P, and Al in an amount of 20 mol% or less based on Me.
　以上の構成によれば、共有結合性が高い元素を含むことによって構造が安定化するため、サイクル特性が向上する。このため、より長寿命の電池を実現できる。 According to the above configuration, the structure is stabilized by containing an element having a high covalent bond property, so that the cycle characteristics are improved. Therefore, a battery having a longer life can be realized.
　また、組成式（１）において、Ｑは、Ｆを含んでもよい。 Further, in the composition formula (1), Q may include F.
　すなわち、Ｑは、Ｆであってもよい。 That is, Q may be F.
　もしくは、Ｑは、Ｃｌ、Ｎ、およびＳからなる群より選択される少なくとも１種の元素と、Ｆとを、含んでもよい。 Alternatively, Q may contain at least one element selected from the group consisting of Cl, N, and S, and F.
　以上の構成によれば、電気陰性度が高いＦによって酸素の一部を置換することで、カチオン－アニオンの相互作用が増加し、電池の放電容量または作動電圧が向上する。また、電気陰性度の高いＦを固溶させることで、Ｆを含まない場合と比較して電子が局在化する。このため、充電時における酸素脱離を抑制することができるため、結晶構造が安定化する。これらの効果が総合的に作用することで、より高容量の電池を実現できる。 According to the above configuration, by substituting a part of oxygen with F having a high electronegativity, the interaction between cation and anion is increased, and the discharge capacity or operating voltage of the battery is improved. Further, by dissolving F having a high electronegativity as a solid solution, electrons are localized as compared with the case where F is not contained. Therefore, oxygen desorption during charging can be suppressed, and the crystal structure is stabilized. By combining these effects, a battery with a higher capacity can be realized.
　また、組成式（１）は、下記の条件、
１．１６６≦ｘ≦１．２３、および
０．７７≦ｙ≦０．８３４、
を満たしてもよい。 The composition formula (1) is based on the following conditions.
1.166 ≤ x ≤ 1.23, and 0.77 ≤ y ≤ 0.834,
May be satisfied.
　以上の構成によれば、より高容量の電池を実現できる。 According to the above configuration, a higher capacity battery can be realized.
　また、組成式（１）は、下記の条件、
１．９≦α≦１．９１７、
０．０８３≦β≦０．１、
を満たしてもよい。 The composition formula (1) is based on the following conditions.
1.9 ≤ α ≤ 1.917,
0.083 ≤ β ≤ 0.1,
May be satisfied.
　以上の構成によれば、酸素の酸化還元による容量が過剰となることを防ぐことができ、電気化学的に不活性なＱの影響が十分に受けられることにより、Ｌｉが脱離した際に構造が安定化する。このため、より高容量の電池を実現できる。 According to the above configuration, it is possible to prevent the capacity from becoming excessive due to the redox of oxygen, and the structure is sufficiently affected by the electrochemically inactive Q when Li is eliminated. Stabilizes. Therefore, a higher capacity battery can be realized.
　組成式（１）において、「Ｌｉ」と「Ｍｅ」の比率は、ｘ／ｙで示される。 In the composition formula (1), the ratio of "Li" and "Me" is represented by x / y.
　組成式（１）は、１．３９≦ｘ／ｙ≦１．６、を満たしてもよい。 The composition formula (1) may satisfy 1.39 ≦ x / y ≦ 1.6.
　以上の構成によれば、より高容量の電池を実現できる。 According to the above configuration, a higher capacity battery can be realized.
　なお、ｘ／ｙが１よりも大きい場合、例えば、組成式ＬｉＭｎＯ2で示される従来の正極活物質よりも、Ｌｉが位置するサイトにおけるＬｉ原子数の割合が高い。これにより、より多くのＬｉを挿入および脱離させることが可能となる。 When x / y is larger than 1, for example, the ratio of the number of Li atoms at the site where Li is located is higher than that of the conventional positive electrode active material represented by the composition formula LiMnO 2 . This makes it possible to insert and remove more Li.
　また、ｘ／ｙが１．３９以上の場合、利用できるＬｉ量が多く、Ｌｉの拡散パスが適切に形成される。このため、より高容量の電池を実現できる。 Further, when x / y is 1.39 or more, the amount of Li that can be used is large, and the diffusion path of Li is appropriately formed. Therefore, a higher capacity battery can be realized.
　また、ｘ／ｙが１．６以下の場合、利用できるＭｅの酸化還元反応が少なくなることを防ぐことができる。この結果、酸素の酸化還元反応を多く利用する必要がなくなる。また、充電時におけるＬｉ脱離時に結晶構造が不安定化し、放電時のＬｉ挿入効率が低下することを防ぐことができる。このため、より高容量の電池を実現できる。 Further, when x / y is 1.6 or less, it is possible to prevent the redox reaction of available Me from being reduced. As a result, it is not necessary to utilize a lot of oxygen redox reactions. In addition, it is possible to prevent the crystal structure from becoming unstable during Li desorption during charging and lowering the Li insertion efficiency during discharging. Therefore, a higher capacity battery can be realized.
　また、組成式（１）は、１．５≦ｘ／ｙ≦１．６、を満たしてもよい。 Further, the composition formula (1) may satisfy 1.5 ≦ x / y ≦ 1.6.
　以上の構成によれば、より高容量の電池を実現できる。 According to the above configuration, a higher capacity battery can be realized.
　組成式（１）において、「Ｏ」と「Ｑ」の比率は、α／βで示される。 In the composition formula (1), the ratio of "O" and "Q" is represented by α / β.
　組成式（１）は、１９≦α／β≦２３．１、を満たしてもよい。 The composition formula (1) may satisfy 19 ≦ α / β ≦ 23.1.
　以上の構成によれば、より高容量の電池を実現できる。 According to the above configuration, a higher capacity battery can be realized.
　なお、α／βが１９以上の場合、酸素の酸化還元による電荷補償量が低下することを防ぐことができる。また、電気化学的に不活性なＱの影響を小さくできるため、電子伝導性が向上する。このため、より高容量の電池を実現できる。 When α / β is 19 or more, it is possible to prevent the charge compensation amount from being reduced due to the redox of oxygen. Further, since the influence of the electrochemically inactive Q can be reduced, the electron conductivity is improved. Therefore, a higher capacity battery can be realized.
　また、α／βが２３．１以下の場合、酸素の酸化還元による容量が過剰となることを防ぐことができ、Ｌｉが脱離した際に構造が安定化する。また、電気化学的に不活性なＱの影響を受けることにより、Ｌｉが脱離した際に構造が安定化する。このため、より高容量の電池を実現できる。 Further, when α / β is 23.1 or less, it is possible to prevent the capacity from becoming excessive due to redox of oxygen, and the structure is stabilized when Li is eliminated. Further, due to the influence of the electrochemically inert Q, the structure is stabilized when Li is eliminated. Therefore, a higher capacity battery can be realized.
　組成式（１）において、「Ｌｉ＋Ｍｅ」と「Ｏ＋Ｑ」の比率（すなわち、「カチオン」と「アニオン」の比率）は、（ｘ＋ｙ）／（α＋β）で示される。 In the composition formula (1), the ratio of "Li + Me" and "O + Q" (that is, the ratio of "cation" and "anion") is represented by (x + y) / (α + β).
　組成式（１）は、０．７５≦（ｘ＋ｙ）／（α＋β）≦１．２、を満たしてもよい。 The composition formula (1) may satisfy 0.75 ≦ (x + y) / (α + β) ≦ 1.2.
　以上の構成によれば、より高容量の電池を実現できる。 According to the above configuration, a higher capacity battery can be realized.
　なお、（ｘ＋ｙ）／（α＋β）が０．７５以上の場合、合成時に分相して不純物が多く生成することを防ぐことができる。このため、より高容量の電池を実現できる。 When (x + y) / (α + β) is 0.75 or more, it is possible to prevent a large amount of impurities from being phase-separated during synthesis. Therefore, a higher capacity battery can be realized.
　また、（ｘ＋ｙ）／（α＋β）が１．２以下の場合、アニオンの欠損量が少ない構造となり、充電時におけるＬｉ脱離時に結晶構造が安定化する。このため、より高容量の電池を実現できる。 Further, when (x + y) / (α + β) is 1.2 or less, the structure has a small amount of anion deficiency, and the crystal structure is stabilized during Li desorption during charging. Therefore, a higher capacity battery can be realized.
　また、組成式（１）は、１．０≦（ｘ＋ｙ）／（α＋β）≦１．２、を満たしてもよい。 Further, the composition formula (1) may satisfy 1.0 ≦ (x + y) / (α + β) ≦ 1.2.
　以上の構成によれば、より高容量の電池を実現できる。 According to the above configuration, a higher capacity battery can be realized.
　また、実施の形態１における正極活物質において、リチウム複合酸化物におけるＬｉの一部は、ＮａあるいはＫなどのアルカリ金属で置換されていてもよい。 Further, in the positive electrode active material according to the first embodiment, a part of Li in the lithium composite oxide may be replaced with an alkali metal such as Na or K.
　また、実施の形態１における正極活物質は、上述のリチウム複合酸化物の粒子を、主成分として（すなわち、正極活物質の全体に対する質量割合で５０％以上（５０質量％以上））、含んでもよい。 Further, the positive electrode active material in the first embodiment may contain the above-mentioned lithium composite oxide particles as a main component (that is, 50% or more (50% by mass or more) in mass ratio with respect to the whole positive electrode active material). Good.
　以上の構成によれば、より高容量の電池を実現できる。 According to the above configuration, a higher capacity battery can be realized.
　また、実施の形態１における正極活物質は、上述のリチウム複合酸化物の粒子を、正極活物質の全体に対する質量割合で７０％以上（７０質量％以上）、含んでもよい。 Further, the positive electrode active material in the first embodiment may contain the above-mentioned lithium composite oxide particles in a mass ratio of 70% or more (70% by mass or more) with respect to the whole positive electrode active material.
　以上の構成によれば、より高容量の電池を実現できる。 According to the above configuration, a higher capacity battery can be realized.
　また、実施の形態１における正極活物質は、上述のリチウム複合酸化物の粒子を、正極活物質の全体に対する質量割合で９０％以上（９０質量％以上）、含んでもよい。 Further, the positive electrode active material in the first embodiment may contain the above-mentioned lithium composite oxide particles in a mass ratio of 90% or more (90% by mass or more) with respect to the whole positive electrode active material.
　以上の構成によれば、より高容量の電池を実現できる。 According to the above configuration, a higher capacity battery can be realized.
　なお、実施の形態１における正極活物質は、上述のリチウム複合酸化物の粒子を含みながら、さらに、不可避的な不純物を含んでもよい。 The positive electrode active material in the first embodiment may contain unavoidable impurities while containing the above-mentioned lithium composite oxide particles.
　また、実施の形態１における正極活物質は、上述のリチウム複合酸化物の粒子を含みながら、さらに、正極活物質を合成する際に用いられる出発原料および副生成物および分解生成物からなる群より選択される少なくとも一つを含んでもよい。 Further, the positive electrode active material in the first embodiment is composed of a group consisting of a starting material, a by-product, and a decomposition product used for synthesizing the positive electrode active material while containing the above-mentioned lithium composite oxide particles. It may contain at least one selected.
　また、実施の形態１における正極活物質は、例えば、混入が不可避的な不純物を除いて、上述のリチウム複合酸化物の粒子のみを、含んでもよい。 Further, the positive electrode active material in the first embodiment may contain only the above-mentioned lithium composite oxide particles, for example, excluding impurities inevitably mixed.
　以上の構成によれば、より高容量の電池を実現できる。 According to the above configuration, a higher capacity battery can be realized.
　＜リチウム複合酸化物の作製方法＞
　以下に、実施の形態１の正極活物質に含まれるリチウム複合酸化物の製造方法の一例が、説明される。 <Method for producing lithium composite oxide>
An example of a method for producing a lithium composite oxide contained in the positive electrode active material of the first embodiment will be described below.
　実施の形態１において、リチウム複合酸化物は、例えば、次の方法により、作製されうる。 In the first embodiment, the lithium composite oxide can be produced, for example, by the following method.
　まず、前駆体であるＭｅＣＯ3を作製する。この前駆体を作製するための原料としては、ＭｅＳＯ4、Ｍｅ（ＮＯ3）2、Ｍｅ（ＣＨ3ＣＯＯ）2等のＭｅを含む化合物と、Ｎａ2ＣＯ3、Ｋ2ＣＯ3、ＮａＨＣＯ3、ＫＨＣＯ3等の炭酸塩と、などが挙げられる。例えば、ＭｅがＭｎの場合には、Ｍｎを含む原料としては、例えば、ＭｎＳＯ4、Ｍｎ（ＮＯ3）2、Ｍｎ（ＣＨ3ＣＯＯ）2など、が挙げられる。 First, the precursor MeCO 3 is prepared. Raw materials for producing this precursor include MeSO 4 , Me (NO 3 ) 2 , Me (CH 3 COO) 2, and other Me-containing compounds, and Na 2 CO 3 , K 2 CO 3 , and Na HCO 3 , Examples include carbonates such as KHCO 3 and the like. For example, when Me is Mn, examples of the raw material containing Mn include MnSO 4 , Mn (NO 3 ) 2 , Mn (CH 3 COO) 2, and the like.
　例えば、Ｍｅを含む化合物を所定の濃度（例えば２ｍｏｌ/Ｌ）となるように純水に溶解させることで、Ｍｅ源を含んだ溶液Ａが作製される。また、炭酸源を所定の濃度（例えば２ｍｏｌ/Ｌ）となるように純水に溶解させることで、炭酸源を含む溶液Ｂが作製される。作製された２つの溶液Ａおよび溶液Ｂを純水に、ｐＨを制御しながら滴下していくことで、前駆体としてのＭｅＣＯ3が得られる。なお、溶液Ｂは、ＮＨ3のような錯形成剤を含んでもよい。 For example, a solution A containing a Me source is prepared by dissolving a compound containing Me in pure water so as to have a predetermined concentration (for example, 2 mol / L). Further, by dissolving the carbonic acid source in pure water so as to have a predetermined concentration (for example, 2 mol / L), a solution B containing the carbonic acid source is prepared. MeCO 3 as a precursor can be obtained by dropping the two prepared solutions A and B into pure water while controlling the pH. The solution B may contain a complex-forming agent such as NH 3 .
　次に、リチウム複合酸化物を作製するにあたり、Ｌｉを含む原料、前駆体としての上記のＭｅＣＯ3、および、Ｑを含む原料を用意する。 Next, in producing the lithium composite oxide, a raw material containing Li, the above-mentioned MeCO 3 as a precursor, and a raw material containing Q are prepared.
　Ｌｉを含む原料としては、例えば、Ｌｉ2Ｏ、Ｌｉ2Ｏ2等の酸化物、ＬｉＦ、Ｌｉ2ＣＯ3、ＬｉＯＨ等の塩類、ＬｉＭｅＯ2、ＬｉＭｅ2Ｏ4等のリチウム複合酸化物、など、が挙げられる。 Examples of the raw material containing Li include oxides such as Li 2 O and Li 2 O 2 , salts such as LiF, Li 2 CO 3 and LiOH, and lithium composite oxides such as LiMeO 2 and LiMe 2 O 4 . Can be mentioned.
　また、Ｑを含む原料としては、例えば、ハロゲン化リチウム、遷移金属ハロゲン化物、遷移金属硫化物、遷移金属窒化物など、が挙げられる。 Examples of the raw material containing Q include lithium halide, transition metal halide, transition metal sulfide, and transition metal nitride.
　例えば、ＱがＦの場合には、Ｆを含む原料としては、例えば、ＬｉＦ、遷移金属フッ化物、など、が挙げられる。 For example, when Q is F, examples of the raw material containing F include LiF, transition metal fluoride, and the like.
　これらの原料を、組成式（１）に示したモル比となるように、秤量する。秤量した原料を、例えば、乾式法または湿式法で混合し、その後、熱処理する。 These raw materials are weighed so as to have the molar ratio shown in the composition formula (1). The weighed raw materials are mixed, for example, by a dry method or a wet method, and then heat-treated.
　これらの工程により、組成式（１）における「ｘ、ｙ、α、および、β」を、組成式（１）で示す範囲において、変化させることができる。 By these steps, "x, y, α, and β" in the composition formula (1) can be changed within the range represented by the composition formula (1).
　このときの熱処理の条件は、実施の形態１におけるリチウム複合酸化物が得られるように適宜設定される。熱処理の最適な条件は、他の製造条件および目標とする組成に依存して異なる。 The conditions of the heat treatment at this time are appropriately set so that the lithium composite oxide according to the first embodiment can be obtained. The optimum conditions for heat treatment depend on other manufacturing conditions and the target composition.
　熱処理の温度は、例えば、２００～９００℃の範囲で、適宜変更することができる。熱処理に要する時間は、例えば、１分から２０時間の範囲で、適宜変更することができる。熱処理の雰囲気としては、大気雰囲気、酸素雰囲気、または、窒素もしくはアルゴンなどの不活性雰囲気、であってもよい。 The temperature of the heat treatment can be appropriately changed in the range of, for example, 200 to 900 ° C. The time required for the heat treatment can be appropriately changed, for example, in the range of 1 minute to 20 hours. The heat treatment atmosphere may be an air atmosphere, an oxygen atmosphere, or an inert atmosphere such as nitrogen or argon.
　また、熱処理は、一段階でなく、数段階に分けて行ってもよい。 Further, the heat treatment may be performed in several stages instead of one stage.
　以上のように、用いる原料、原料混合物の混合条件、および熱処理条件を調整することにより、実質的に、実施の形態１における正極活物質を構成するリチウム複合酸化物を得ることができる。 As described above, by adjusting the raw materials to be used, the mixing conditions of the raw material mixture, and the heat treatment conditions, the lithium composite oxide constituting the positive electrode active material according to the first embodiment can be substantially obtained.
　なお、上述のとおり、得られたリチウム複合酸化物が有する結晶構造の空間群は、例えば、Ｘ線回折測定または電子線回折測定により、特定することができる。これにより、得られたリチウム複合酸化物が、空間群Ｃ２／ｍ、または、Ｒ３－ｍに属する結晶構造を有することを確認できる。 As described above, the space group of the crystal structure of the obtained lithium composite oxide can be specified by, for example, X-ray diffraction measurement or electron diffraction measurement. From this, it can be confirmed that the obtained lithium composite oxide has a crystal structure belonging to the space group C2 / m or R3-m.
　なお、得られたリチウム複合酸化物の平均組成は、例えば、ＩＣＰ発光分光分析法、不活性ガス溶融－赤外線吸収法、イオンクロマトグラフィー、またはそれら分析方法の組み合わせにより、決定することができる。 The average composition of the obtained lithium composite oxide can be determined by, for example, ICP emission spectroscopy, inert gas melting-infrared absorption method, ion chromatography, or a combination of these analysis methods.
　以上のように、実施の形態１の正極活物質に含まれるリチウム複合酸化物の製造方法は、Ｍｅの炭酸塩である前駆体を作製する工程（ａ）と、Ｍｅを除く他の原料を用意する工程（ｂ）と、前記前駆体および前記他の原料とを混合し、得られた混合物を熱処理することによりリチウム複合酸化物を得る工程（ｃ）と、を包含する。 As described above, in the method for producing the lithium composite oxide contained in the positive electrode active material of the first embodiment, the step (a) for producing a precursor which is a carbonate of Me and other raw materials excluding Me are prepared. The step (b) is included, and the step (c) of mixing the precursor and the other raw materials and heat-treating the obtained mixture to obtain a lithium composite oxide.
　上述の工程（ｃ）は、上述のそれぞれの原料を、Ｍｅに対して、Ｌｉが１．３９以上１．６以下のモル比となる割合で混合し、混合原料を調整する工程を、包含してもよい。 The above-mentioned step (c) includes a step of adjusting the mixed raw materials by mixing each of the above-mentioned raw materials at a ratio of Li of 1.39 or more and 1.6 or less with respect to Me. You may.
　このとき、上述の工程（ｂ）は、原料となるリチウム化合物を、公知の方法で作製する工程を、包含してもよい。 At this time, the above-mentioned step (b) may include a step of producing a lithium compound as a raw material by a known method.
　また、上述の工程（ｃ）は、上述のそれぞれの原料を、Ｍｅに対して、Ｌｉが１．５以上１．６以下のモル比となる割合で混合し、混合原料を調整する工程を、包含してもよい。 Further, in the above-mentioned step (c), each of the above-mentioned raw materials is mixed with Me at a molar ratio of Li of 1.5 or more and 1.6 or less to prepare a mixed raw material. It may be included.
　また、上述の工程（ｃ）は、熱処理により反応させる工程を、２段階、包含してもよい。 Further, the above-mentioned step (c) may include a step of reacting by heat treatment in two steps.
　（実施の形態２）
　以下、実施の形態２が説明される。なお、上述の実施の形態１と重複する説明は、適宜、省略される。 (Embodiment 2)
The second embodiment will be described below. The description that overlaps with the above-described first embodiment will be omitted as appropriate.
　実施の形態２における電池は、上述の実施の形態１における正極活物質を含む正極と、負極と、電解質と、を備える。 The battery according to the second embodiment includes a positive electrode containing the positive electrode active material according to the first embodiment, a negative electrode, and an electrolyte.
　以上の構成によれば、高容量の電池を実現できる。 According to the above configuration, a high capacity battery can be realized.
　また、実施の形態２における電池において、正極は、正極活物質層を備えてもよい。このとき、正極活物質層は、上述の実施の形態１における正極活物質を、主成分として（すなわち、正極活物質層の全体に対する質量割合で５０％以上（５０質量％以上））、含んでもよい。 Further, in the battery according to the second embodiment, the positive electrode may include a positive electrode active material layer. At this time, the positive electrode active material layer may contain the positive electrode active material according to the first embodiment as a main component (that is, 50% or more (50% by mass or more) in mass ratio with respect to the entire positive electrode active material layer). Good.
　以上の構成によれば、より高容量の電池を実現できる。 According to the above configuration, a higher capacity battery can be realized.
　もしくは、実施の形態２における電池において、正極活物質層は、上述の実施の形態１における正極活物質を、正極活物質層の全体に対する質量割合で７０％以上（７０質量％以上）、含んでもよい。 Alternatively, in the battery of the second embodiment, the positive electrode active material layer may contain the positive electrode active material of the above-described first embodiment in a mass ratio of 70% or more (70% by mass or more) with respect to the entire positive electrode active material layer. Good.
　以上の構成によれば、より高容量の電池を実現できる。 According to the above configuration, a higher capacity battery can be realized.
　もしくは、実施の形態２における電池において、正極活物質層は、上述の実施の形態１における正極活物質を、正極活物質層の全体に対する質量割合で９０％以上（９０質量％以上）、含んでもよい。 Alternatively, in the battery of the second embodiment, the positive electrode active material layer may contain the positive electrode active material of the above-described first embodiment in a mass ratio of 90% or more (90% by mass or more) with respect to the entire positive electrode active material layer. Good.
　以上の構成によれば、より高容量の電池を実現できる。 According to the above configuration, a higher capacity battery can be realized.
　実施の形態２における電池は、例えば、リチウムイオン二次電池、非水電解質二次電池、全固体電池、など、として、構成されうる。 The battery according to the second embodiment can be configured as, for example, a lithium ion secondary battery, a non-aqueous electrolyte secondary battery, an all-solid-state battery, and the like.
　すなわち、実施の形態２における電池において、負極は、例えば、リチウムイオンを吸蔵および放出しうる負極活物質を含んでもよい。あるいは、負極は、例えば、リチウム金属を負極活物質として溶解および析出させうる材料を含んでもよい。 That is, in the battery of the second embodiment, the negative electrode may include, for example, a negative electrode active material capable of occluding and releasing lithium ions. Alternatively, the negative electrode may contain, for example, a material capable of dissolving and precipitating lithium metal as the negative electrode active material.
　また、実施の形態２における電池において、電解質は、例えば、非水電解質（例えば、非水電解液）であってもよい。 Further, in the battery according to the second embodiment, the electrolyte may be, for example, a non-aqueous electrolyte (for example, a non-aqueous electrolyte solution).
　また、実施の形態２における電池において、電解質は、例えば、固体電解質であってもよい。 Further, in the battery according to the second embodiment, the electrolyte may be, for example, a solid electrolyte.
　図２は、実施の形態２における電池の一例である電池１０の概略構成を示す断面図である。 FIG. 2 is a cross-sectional view showing a schematic configuration of a battery 10 which is an example of a battery according to the second embodiment.
　図２に示されるように、電池１０は、正極２１と、負極２２と、セパレータ１４と、ケース１１と、封口板１５と、ガスケット１８と、を備えている。 As shown in FIG. 2, the battery 10 includes a positive electrode 21, a negative electrode 22, a separator 14, a case 11, a sealing plate 15, and a gasket 18.
　セパレータ１４は、正極２１と負極２２との間に、配置されている。 The separator 14 is arranged between the positive electrode 21 and the negative electrode 22.
　正極２１と負極２２とセパレータ１４とには、例えば、非水電解質（例えば、非水電解液）が含浸されている。 The positive electrode 21, the negative electrode 22, and the separator 14 are impregnated with, for example, a non-aqueous electrolyte (for example, a non-aqueous electrolyte solution).
　正極２１と負極２２とセパレータ１４とによって、電極群が形成されている。 An electrode group is formed by the positive electrode 21, the negative electrode 22, and the separator 14.
　電極群は、ケース１１の中に収められている。 The electrode group is housed in the case 11.
　ガスケット１８と封口板１５とにより、ケース１１が閉じられている。 The case 11 is closed by the gasket 18 and the sealing plate 15.
　正極２１は、正極集電体１２と、正極集電体１２の上に配置された正極活物質層１３と、を備えている。 The positive electrode 21 includes a positive electrode current collector 12 and a positive electrode active material layer 13 arranged on the positive electrode current collector 12.
　正極集電体１２は、例えば、金属材料（例えば、アルミニウム、ステンレス、ニッケル、鉄、チタン、銅、パラジウム、金、および白金からなる群より選択される少なくとも１種、またはそれらの合金）で作られている。 The positive electrode current collector 12 is made of, for example, a metal material (for example, at least one selected from the group consisting of aluminum, stainless steel, nickel, iron, titanium, copper, palladium, gold, and platinum, or an alloy thereof). Has been done.
　なお、正極集電体１２を省略し、ケース１１を正極集電体として使用することも可能である。 It is also possible to omit the positive electrode current collector 12 and use the case 11 as the positive electrode current collector.
　正極活物質層１３は、上述の実施の形態１における正極活物質を含む。 The positive electrode active material layer 13 contains the positive electrode active material according to the first embodiment described above.
　正極活物質層１３は、必要に応じて、例えば、添加剤（導電剤、イオン伝導補助剤、結着剤、など）を含んでいてもよい。 The positive electrode active material layer 13 may contain, for example, an additive (a conductive agent, an ionic conduction auxiliary agent, a binder, etc.), if necessary.
　負極２２は、負極集電体１６と、負極集電体１６の上に配置された負極活物質層１７と、を備えている。 The negative electrode 22 includes a negative electrode current collector 16 and a negative electrode active material layer 17 arranged on the negative electrode current collector 16.
　負極集電体１６は、例えば、金属材料（例えば、アルミニウム、ステンレス、ニッケル、鉄、チタン、銅、パラジウム、金、および白金からなる群より選択される少なくとも１種、またはそれらの合金）で作られている。 The negative electrode current collector 16 is made of, for example, a metal material (for example, at least one selected from the group consisting of aluminum, stainless steel, nickel, iron, titanium, copper, palladium, gold, and platinum, or an alloy thereof). Has been done.
　なお、負極集電体１６を省略し、封口板１５を負極集電体として使用することも可能である。 It is also possible to omit the negative electrode current collector 16 and use the sealing plate 15 as the negative electrode current collector.
　負極活物質層１７は、負極活物質を含んでいる。 The negative electrode active material layer 17 contains a negative electrode active material.
　負極活物質層１７は、必要に応じて、例えば、添加剤（導電剤、イオン伝導補助剤、結着剤、など）を含んでいてもよい。 The negative electrode active material layer 17 may contain, for example, additives (conductive agent, ionic conduction auxiliary agent, binder, etc.), if necessary.
　負極活物質として、金属材料、炭素材料、酸化物、窒化物、錫化合物、珪素化合物、など、が使用されうる。 As the negative electrode active material, metal materials, carbon materials, oxides, nitrides, tin compounds, silicon compounds, etc. can be used.
　金属材料は、単体の金属であってもよい。もしくは、金属材料は、合金であってもよい。金属材料の例として、リチウム金属、リチウム合金、など、が挙げられる。 The metal material may be a single metal. Alternatively, the metal material may be an alloy. Examples of metal materials include lithium metal, lithium alloy, and the like.
　炭素材料の例として、天然黒鉛、コークス、黒鉛化途上炭素、炭素繊維、球状炭素、人造黒鉛、非晶質炭素、など、が挙げられる。 Examples of carbon materials include natural graphite, coke, graphitizing carbon, carbon fiber, spherical carbon, artificial graphite, amorphous carbon, and the like.
　容量密度の観点から、負極活物質として、珪素（Ｓｉ）、錫（Ｓｎ）、珪素化合物、錫化合物、を使用できる。珪素化合物および錫化合物は、それぞれ、合金または固溶体であってもよい。 From the viewpoint of capacitance density, silicon (Si), tin (Sn), silicon compound, and tin compound can be used as the negative electrode active material. The silicon compound and the tin compound may be alloys or solid solutions, respectively.
　珪素化合物の例として、ＳｉＯx（ここで、０．０５＜ｘ＜１．９５）が挙げられる。また、ＳｉＯxの一部の珪素を他の元素で置換することによって得られた化合物（合金または固溶体）も使用できる。ここで、他の元素とは、ホウ素、マグネシウム、ニッケル、チタン、モリブデン、コバルト、カルシウム、クロム、銅、鉄、マンガン、ニオブ、タンタル、バナジウム、タングステン、亜鉛、炭素、窒素および錫からなる群より選択される少なくとも１種である。 Examples of silicon compounds include SiO x (where 0.05 <x <1.95). Further, a compound (alloy or solid solution) obtained by substituting a part of silicon of SiO x with another element can also be used. Here, the other elements are from the group consisting of boron, magnesium, nickel, titanium, molybdenum, cobalt, calcium, chromium, copper, iron, manganese, niobium, tantalum, vanadium, tungsten, zinc, carbon, nitrogen and tin. At least one selected.
　錫化合物の例として、Ｎｉ2Ｓｎ4、Ｍｇ2Ｓｎ、ＳｎＯx（ここで、０＜ｘ＜２）、ＳｎＯ2、ＳｎＳｉＯ3、など、が挙げられる。これらから選択される１種の錫化合物が、単独で使用されてもよい。もしくは、これらから選択される２種以上の錫化合物の組み合わせが、使用されてもよい。 Examples of the tin compound include Ni 2 Sn 4 , Mg 2 Sn, SnO x (here, 0 <x <2), SnO 2 , SnSiO 3 , and the like. One kind of tin compound selected from these may be used alone. Alternatively, a combination of two or more tin compounds selected from these may be used.
　また、負極活物質の形状は特に限定されない。負極活物質としては、公知の形状（粒子状、繊維状、など）を有する負極活物質が使用されうる。 The shape of the negative electrode active material is not particularly limited. As the negative electrode active material, a negative electrode active material having a known shape (particulate, fibrous, etc.) can be used.
　また、リチウムを負極活物質層１７に補填する（吸蔵させる）ための方法は、特に限定されない。この方法としては、具体的には、（ａ）真空蒸着法などの気相法によってリチウムを負極活物質層１７に堆積させる方法、（ｂ）リチウム金属箔と負極活物質層１７とを接触させて両者を加熱する方法がある。いずれの方法においても、熱によってリチウムを負極活物質層１７に拡散させることができる。また、リチウムを電気化学的に負極活物質層１７に吸蔵させる方法もある。具体的には、リチウムを有さない負極２２およびリチウム金属箔（正極）を用いて電池を組み立てる。その後、負極２２にリチウムが吸蔵されるように、その電池を充電する。 Further, the method for filling (occluding) lithium in the negative electrode active material layer 17 is not particularly limited. Specifically, as this method, (a) a method of depositing lithium on the negative electrode active material layer 17 by a vapor phase method such as a vacuum vapor deposition method, and (b) a lithium metal foil and the negative electrode active material layer 17 are brought into contact with each other. There is a method of heating both. In either method, lithium can be diffused into the negative electrode active material layer 17 by heat. There is also a method of electrochemically storing lithium in the negative electrode active material layer 17. Specifically, the battery is assembled using the negative electrode 22 having no lithium and the lithium metal foil (positive electrode). Then, the battery is charged so that lithium is occluded in the negative electrode 22.
　正極２１および負極２２の結着剤としては、ポリフッ化ビニリデン、ポリテトラフルオロエチレン、ポリエチレン、ポリプロピレン、アラミド樹脂、ポリアミド、ポリイミド、ポリアミドイミド、ポリアクリルニトリル、ポリアクリル酸、ポリアクリル酸メチルエステル、ポリアクリル酸エチルエステル、ポリアクリル酸ヘキシルエステル、ポリメタクリル酸、ポリメタクリル酸メチルエステル、ポリメタクリル酸エチルエステル、ポリメタクリル酸ヘキシルエステル、ポリ酢酸ビニル、ポリビニルピロリドン、ポリエーテル、ポリエーテルサルフォン、ヘキサフルオロポリプロピレン、スチレンブタジエンゴム、カルボキシメチルセルロース、など、が使用されうる。または、結着剤として、テトラフルオロエチレン、ヘキサフルオロエタン、ヘキサフルオロプロピレン、パーフルオロアルキルビニルエーテル、フッ化ビニリデン、クロロトリフルオロエチレン、エチレン、プロピレン、ペンタフルオロプロピレン、フルオロメチルビニルエーテル、アクリル酸、ヘキサジエン、からなる群より選択される２種以上の材料の共重合体が、使用されてもよい。さらに、上述の材料から選択される２種以上の材料の混合物が、結着剤として、使用されてもよい。 Examples of the binder for the positive electrode 21 and the negative electrode 22 include polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, aramid resin, polyamide, polyimide, polyamideimide, polyacrylic nitrile, polyacrylic acid, polyacrylic acid methyl ester, and poly. Acrylic ethyl ester, Polyacrylic acid hexyl ester, Polymethacrylic acid, Polymethacrylic acid methyl ester, Polymethacrylic acid ethyl ester, Polymethacrylic acid hexyl ester, Polyvinyl acetate, Polypolypyrrolidone, polyether, Polyether sulfone, Hexafluoro Polypropylene, styrene butadiene rubber, carboxymethyl cellulose, etc. can be used. Alternatively, as a binder, tetrafluoroethylene, hexafluoroethane, hexafluoropropylene, perfluoroalkyl vinyl ether, vinylidene fluoride, chlorotrifluoroethylene, ethylene, propylene, pentafluoropropylene, fluoromethyl vinyl ether, acrylic acid, hexadiene, Copolymers of two or more materials selected from the group consisting of may be used. Further, a mixture of two or more materials selected from the above materials may be used as a binder.
　正極２１および負極２２の導電剤としては、グラファイト、カーボンブラック、導電性繊維、フッ化黒鉛、金属粉末、導電性ウィスカー、導電性金属酸化物、有機導電性材料、など、が使用されうる。グラファイトの例としては、天然黒鉛および人造黒鉛が挙げられる。カーボンブラックの例としては、アセチレンブラック、ケッチェンブラック（登録商標）、チャンネルブラック、ファーネスブラック、ランプブラック、サーマルブラックが挙げられる。金属粉末の例としては、アルミニウム粉末が挙げられる。導電性ウィスカーの例としては、酸化亜鉛ウィスカーおよびチタン酸カリウムウィスカーが挙げられる。導電性金属酸化物の例としては、酸化チタンが挙げられる。有機導電性材料の例としては、フェニレン誘導体が挙げられる。 As the conductive agent for the positive electrode 21 and the negative electrode 22, graphite, carbon black, conductive fiber, graphite fluoride, metal powder, conductive whisker, conductive metal oxide, organic conductive material, or the like can be used. Examples of graphite include natural graphite and artificial graphite. Examples of carbon black include acetylene black, Ketjen black (registered trademark), channel black, furnace black, lamp black, and thermal black. An example of a metal powder is aluminum powder. Examples of conductive whiskers include zinc oxide whiskers and potassium titanate whiskers. Examples of conductive metal oxides include titanium oxide. Examples of organic conductive materials include phenylene derivatives.
　なお、上述の導電剤として使用されうる材料を用いて、上述の結着剤の表面の少なくとも一部を被覆してもよい。例えば、上述の結着剤は、カーボンブラックにより表面を被覆されてもよい。これにより、電池の容量を向上させることができる。 In addition, at least a part of the surface of the above-mentioned binder may be coated with a material that can be used as the above-mentioned conductive agent. For example, the above-mentioned binder may be coated on the surface with carbon black. Thereby, the capacity of the battery can be improved.
　セパレータ１４としては、大きいイオン透過度および十分な機械的強度を有する材料が使用されうる。このような材料の例としては、微多孔性薄膜、織布、不織布、など、が挙げられる。具体的に、セパレータ１４は、ポリプロピレン、ポリエチレンなどのポリオレフィンで作られていることが望ましい。ポリオレフィンで作られたセパレータ１４は、優れた耐久性を有するだけでなく、過度に加熱されたときにシャットダウン機能を発揮できる。セパレータ１４の厚さは、例えば、１０～３００μｍ（または１０～４０μｍ）の範囲にある。セパレータ１４は、１種の材料で構成された単層膜であってもよい。もしくは、セパレータ１４は、２種以上の材料で構成された複合膜（または、多層膜）であってもよい。セパレータ１４の空孔率は、例えば、３０～７０％（または３５～６０％）の範囲にある。「空孔率」とは、セパレータ１４の全体の体積に占める空孔の体積の割合を意味する。「空孔率」は、例えば、水銀圧入法によって測定される。 As the separator 14, a material having a large ion permeability and sufficient mechanical strength can be used. Examples of such materials include microporous thin films, woven fabrics, non-woven fabrics, and the like. Specifically, it is desirable that the separator 14 is made of a polyolefin such as polypropylene or polyethylene. The separator 14 made of polyolefin not only has excellent durability, but can also exhibit a shutdown function when overheated. The thickness of the separator 14 is, for example, in the range of 10 to 300 μm (or 10 to 40 μm). The separator 14 may be a monolayer film made of one kind of material. Alternatively, the separator 14 may be a composite film (or a multilayer film) composed of two or more kinds of materials. The porosity of the separator 14 is, for example, in the range of 30-70% (or 35-60%). The “vacancy ratio” means the ratio of the volume of the pores to the total volume of the separator 14. The "vacancy rate" is measured, for example, by the mercury intrusion method.
　非水電解液は、非水溶媒と、非水溶媒に溶けたリチウム塩と、を含む。 The non-aqueous electrolyte solution contains a non-aqueous solvent and a lithium salt dissolved in the non-aqueous solvent.
　非水溶媒としては、環状炭酸エステル溶媒、鎖状炭酸エステル溶媒、環状エーテル溶媒、鎖状エーテル溶媒、環状エステル溶媒、鎖状エステル溶媒、フッ素溶媒、など、が使用されうる。 As the non-aqueous solvent, a cyclic carbonate solvent, a chain carbonate solvent, a cyclic ether solvent, a chain ether solvent, a cyclic ester solvent, a chain ester solvent, a fluorine solvent, or the like can be used.
　環状炭酸エステル溶媒の例としては、エチレンカーボネート、プロピレンカーボネート、ブチレンカーボネート、など、が挙げられる。 Examples of the cyclic carbonate solvent include ethylene carbonate, propylene carbonate, butylene carbonate, and the like.
　鎖状炭酸エステル溶媒の例としては、ジメチルカーボネート、エチルメチルカーボネート、ジエチルカーボネート、など、が挙げられる。 Examples of the chain carbonate ester solvent include dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, and the like.
　環状エーテル溶媒の例としては、テトラヒドロフラン、１、４－ジオキサン、１、３－ジオキソラン、など、が挙げられる。 Examples of the cyclic ether solvent include tetrahydrofuran, 1,4-dioxane, 1,3-dioxolane, and the like.
　鎖状エーテル溶媒としては、１、２－ジメトキシエタン、１、２－ジエトキシエタン、など、が挙げられる。 Examples of the chain ether solvent include 1,2-dimethoxyethane, 1,2-diethoxyethane, and the like.
　環状エステル溶媒の例としては、γ－ブチロラクトン、など、が挙げられる。 Examples of the cyclic ester solvent include γ-butyrolactone and the like.
　鎖状エステル溶媒の例としては、酢酸メチル、など、が挙げられる。 Examples of the chain ester solvent include methyl acetate, and the like.
　フッ素溶媒の例としては、フルオロエチレンカーボネート、フルオロプロピオン酸メチル、フルオロベンゼン、フルオロエチルメチルカーボネート、フルオロジメチレンカーボネート、など、が挙げられる。 Examples of the fluorine solvent include fluoroethylene carbonate, methyl fluoropropionate, fluorobenzene, fluoroethyl methyl carbonate, fluorodimethylene carbonate, and the like.
　非水溶媒として、これらから選択される１種の非水溶媒が、単独で、使用されうる。もしくは、非水溶媒として、これらから選択される２種以上の非水溶媒の組み合わせが、使用されうる。 As the non-aqueous solvent, one kind of non-aqueous solvent selected from these can be used alone. Alternatively, as the non-aqueous solvent, a combination of two or more non-aqueous solvents selected from these can be used.
　非水電解液には、フルオロエチレンカーボネート、フルオロプロピオン酸メチル、フルオロベンゼン、フルオロエチルメチルカーボネート、フルオロジメチレンカーボネートからなる群より選択される少なくとも１種のフッ素溶媒が含まれていてもよい。 The non-aqueous electrolytic solution may contain at least one fluorine solvent selected from the group consisting of fluoroethylene carbonate, methyl fluoropropionate, fluorobenzene, fluoroethyl methyl carbonate, and fluorodimethylene carbonate.
　これらのフッ素溶媒が非水電解液に含まれていると、非水電解液の耐酸化性が向上する。 When these fluorine solvents are contained in the non-aqueous electrolytic solution, the oxidation resistance of the non-aqueous electrolytic solution is improved.
　その結果、高い電圧で電池１０を充電する場合にも、電池１０を安定して動作させることが可能となる。 As a result, even when the battery 10 is charged with a high voltage, the battery 10 can be operated stably.
　また、実施の形態２における電池において、電解質は、固体電解質であってもよい。 Further, in the battery according to the second embodiment, the electrolyte may be a solid electrolyte.
　固体電解質としては、有機ポリマー固体電解質、酸化物固体電解質、硫化物固体電解質、など、が用いられる。 As the solid electrolyte, an organic polymer solid electrolyte, an oxide solid electrolyte, a sulfide solid electrolyte, etc. are used.
　有機ポリマー固体電解質としては、例えば高分子化合物と、リチウム塩との化合物が用いられうる。 As the organic polymer solid electrolyte, for example, a compound of a polymer compound and a lithium salt can be used.
　高分子化合物はエチレンオキシド構造を有していてもよい。エチレンオキシド構造を有することで、リチウム塩を多く含有することができ、イオン導電率をより高めることができる。 The polymer compound may have an ethylene oxide structure. By having an ethylene oxide structure, a large amount of lithium salt can be contained, and the ionic conductivity can be further increased.
　酸化物固体電解質としては、例えば、ＬｉＴｉ2（ＰＯ4）3およびその元素置換体を代表とするＮＡＳＩＣＯＮ型固体電解質、（ＬａＬｉ）ＴｉＯ3系のペロブスカイト型固体電解質、Ｌｉ14ＺｎＧｅ4Ｏ16、Ｌｉ4ＳｉＯ4、ＬｉＧｅＯ4およびその元素置換体を代表とするＬＩＳＩＣＯＮ型固体電解質、Ｌｉ7Ｌａ3Ｚｒ2Ｏ12およびその元素置換体を代表とするガーネット型固体電解質、Ｌｉ3ＮおよびそのＨ置換体、Ｌｉ3ＰＯ4およびそのＮ置換体、など、が用いられうる。 Examples of the oxide solid electrolyte include a NASICON type solid electrolyte typified by LiTi 2 (PO 4 ) 3 and its element substituent, a (LaLi) TiO 3 type perovskite type solid electrolyte, Li 14 ZnGe 4 O 16 , Li. 4 SiO 4 , LiGeO 4 and LISION type solid electrolyte typified by its element substitution product, Li 7 La 3 Zr 2 O 12 and garnet type solid electrolyte typified by its element substitution product, Li 3 N and its H substitution product , Li 3 PO 4 and its N-substituted products, and the like can be used.
　硫化物固体電解質としては、例えば、Ｌｉ2Ｓ－Ｐ2Ｓ5、Ｌｉ2Ｓ－ＳｉＳ2、Ｌｉ2Ｓ－Ｂ2Ｓ3、Ｌｉ2Ｓ－ＧｅＳ2、Ｌｉ3.25Ｇｅ0.25Ｐ0.75Ｓ4、Ｌｉ10ＧｅＰ2Ｓ12、など、が用いられうる。また、これらに、ＬｉＸ（Ｘ：Ｆ、Ｃｌ、Ｂｒ、Ｉ）、ＭＯy、ＬｉxＭＯy（Ｍ：Ｐ、Ｓｉ、Ｇｅ、Ｂ、Ａｌ、Ｇａ、Ｉｎのいずれか）（ｘ、ｙ：自然数）などが、添加されてもよい。 The sulfide solid electrolyte, for example, Li 2 S-P 2 S 5, Li 2 S-SiS 2, Li 2 S-B 2 S 3, Li 2 S-GeS 2, Li 3.25 Ge 0.25 P 0.75 S 4, Li 10 GeP 2 S 12 , etc. can be used. In addition, LiX (X: F, Cl, Br, I), MO y , Li x MO y (any of M: P, Si, Ge, B, Al, Ga, In) (x, y: Natural numbers) and the like may be added.
　これらの中でも、特に、硫化物固体電解質は、成形性に富み、イオン伝導性が高い。このため、固体電解質として、硫化物固体電解質を用いることで、より高エネルギー密度の電池を実現できる。 Among these, the sulfide solid electrolyte is particularly rich in moldability and high ionic conductivity. Therefore, by using a sulfide solid electrolyte as the solid electrolyte, a battery having a higher energy density can be realized.
　また、硫化物固体電解質の中でも、Ｌｉ2Ｓ－Ｐ2Ｓ5は、電気化学的安定性が高く、よりイオン伝導性が高い。このため、固体電解質として、Ｌｉ2Ｓ－Ｐ2Ｓ5を用いれば、より高エネルギー密度の電池を実現できる。 Further, among the sulfide solid electrolytes, Li 2 SP 2 S 5 has high electrochemical stability and higher ionic conductivity. Therefore, if Li 2 SP 2 S 5 is used as the solid electrolyte, a battery having a higher energy density can be realized.
　なお、固体電解質層は、上述の非水電解液を含んでもよい。 The solid electrolyte layer may contain the above-mentioned non-aqueous electrolyte solution.
　固体電解質層が非水電解液を含むことで、活物質と固体電解質との間でのリチウムイオン授受が容易になる。その結果、より高エネルギー密度の電池を実現できる。 Since the solid electrolyte layer contains a non-aqueous electrolyte solution, it becomes easy to transfer lithium ions between the active material and the solid electrolyte. As a result, a battery with a higher energy density can be realized.
　なお、固体電解質層は、固体電解質に加えて、ゲル電解質、イオン液体、など、を含んでもよい。 The solid electrolyte layer may contain a gel electrolyte, an ionic liquid, etc. in addition to the solid electrolyte.
　ゲル電解質は、ポリマー材料に非水電解液を含ませたものを用いることができる。ポリマー材料として、ポリエチレンオキシド、ポリアクリルニトリル、ポリフッ化ビニリデン、およびポリメチルメタクリレート、もしくはエチレンオキシド結合を有するポリマーが用いられてもよい。 As the gel electrolyte, a polymer material containing a non-aqueous electrolyte solution can be used. As the polymer material, a polymer having polyethylene oxide, polyacrylic nitrile, polyvinylidene fluoride, and polymethyl methacrylate, or ethylene oxide bond may be used.
　イオン液体を構成するカチオンは、テトラアルキルアンモニウム、テトラアルキルホスホニウムなどの脂肪族鎖状４級塩類、ピロリジニウム類、モルホリニウム類、イミダゾリニウム類、テトラヒドロピリミジニウム類、ピペラジニウム類、ピペリジニウム類などの脂肪族環状アンモニウム、ピリジニウム類、イミダゾリウム類などの含窒ヘテロ環芳香族カチオンなどであってもよい。イオン液体を構成するアニオンは、ＰＦ6 -、ＢＦ4 -、ＳｂＦ6 -、ＡｓＦ6 -、ＳＯ3ＣＦ3 -、Ｎ（ＳＯ2ＣＦ3）2 -、Ｎ（ＳＯ2Ｃ2Ｆ5）2 -、Ｎ（ＳＯ2ＣＦ3）（ＳＯ2Ｃ4Ｆ9）-、Ｃ（ＳＯ2ＣＦ3）3 -などであってもよい。また、イオン液体はリチウム塩を含有してもよい。 The cations that make up the ionic liquid are aliphatic quaternary salts such as tetraalkylammonium and tetraalkylphosphonium, pyrrolidiniums, morpholiniums, imidazoliniums, tetrahydropyrimidiniums, piperaziniums, piperidiniums and other fats. It may be a nitrogen-containing heterocyclic aromatic cation such as group cyclic ammonium, pyridiniums, or imidazoliums. Anion, PF 6 constituting the ionic liquid -, BF 4 -, SbF 6 -, AsF 6 -, SO 3 CF 3 -, N (SO 2 CF 3) 2 -, N (SO 2 C 2 F 5) 2 -, N (SO 2 CF 3 ) (SO 2 C 4 F 9) -, C (SO 2 CF 3) 3 - , or the like. Further, the ionic liquid may contain a lithium salt.
　リチウム塩としては、ＬｉＰＦ6、ＬｉＢＦ4、ＬｉＳｂＦ6、ＬｉＡｓＦ6、ＬｉＳＯ3ＣＦ3、ＬｉＮ（ＳＯ2ＣＦ3）2、ＬｉＮ（ＳＯ2Ｃ2Ｆ5）2、ＬｉＮ（ＳＯ2ＣＦ3）（ＳＯ2Ｃ4Ｆ9）、ＬｉＣ（ＳＯ2ＣＦ3）3、など、が使用されうる。リチウム塩として、これらから選択される１種のリチウム塩が、単独で、使用されうる。もしくは、リチウム塩として、これらから選択される２種以上のリチウム塩の混合物が、使用されうる。リチウム塩の濃度は、例えば、０．５～２ｍｏｌ／リットルの範囲にある。 The lithium salt, LiPF 6, LiBF 4, LiSbF 6, LiAsF 6, LiSO 3 CF 3, LiN (SO 2 CF 3) 2, LiN (SO 2 C 2 F 5) 2, LiN (SO 2 CF 3) ( SO 2 C 4 F 9 ), LiC (SO 2 CF 3 ) 3 , etc. can be used. As the lithium salt, one type of lithium salt selected from these can be used alone. Alternatively, as the lithium salt, a mixture of two or more kinds of lithium salts selected from these can be used. The concentration of lithium salt is, for example, in the range of 0.5 to 2 mol / liter.
　なお、実施の形態２における電池は、コイン型、円筒型、角型、シート型、ボタン型、扁平型、積層型、など、種々の形状の電池として、構成されうる。 The battery according to the second embodiment can be configured as a battery having various shapes such as a coin type, a cylindrical type, a square type, a sheet type, a button type, a flat type, and a laminated type.
　＜実施例１＞
　（実施例）
　［正極活物質の作製］
　ＭｎＳＯ4・５Ｈ2Ｏと、ＮｉＳＯ4・６Ｈ2Ｏと、ＣｏＳＯ4・７Ｈ2Ｏとを、Ｍｎ／Ｃｏ／Ｎｉ＝５．４／１．３／１．３のモル比となるようにそれぞれ秤量した。得られた原料を、Ｍｎ＋Ｃｏ＋Ｎｉの濃度が２ｍｏｌ／Ｌとなるように純水に溶解し、Ｍｎ、Ｃｏ、およびＮｉを含む溶液（すなわち、Ｍｅ源を含む溶液）を得た。また、別の容器中に、ＫＨＣＯ3の濃度が２ｍｏｌ／ＬとなるようにＫＨＣＯ3を純水に溶解して、ＫＨＣＯ3溶液を得た。 <Example 1>
(Example)
[Preparation of positive electrode active material]
And MnSO 4 · 5H 2 O, and NiSO 4 · 6H 2 O, and CoSO 4 · 7H 2 O, Mn / Co / Ni = 5.4 / 1.3 / 1.3 molar ratio so as to each Weighed. The obtained raw material was dissolved in pure water so that the concentration of Mn + Co + Ni was 2 mol / L to obtain a solution containing Mn, Co, and Ni (that is, a solution containing a Me source). Also, in separate containers, the KHCO 3 so that the concentration of KHCO 3 is 2 mol / L was dissolved in purified water to give a KHCO 3 solution.
　次に、１Ｌのオーバーフローパイプを備えた反応容器に、５００ｍＬの純水を用意した。この純水に対して、Ｍｅ源を含む溶液を０．７ｍＬ／ｍｉｎで滴下し、かつｐＨを７．５に保つようにＫＨＣＯ3溶液を滴下した。液温を６０℃に保ち、５００ｒｐｍで攪拌しながら、Ｍｅ源とＫＨＣＯ3との反応を６時間続けた。 Next, 500 mL of pure water was prepared in a reaction vessel equipped with a 1 L overflow pipe. To this pure water, a solution containing a Me source was added dropwise at 0.7 mL / min, and a KHCO 3 solution was added dropwise so as to maintain the pH at 7.5. The reaction between the Me source and KHCO 3 was continued for 6 hours while keeping the liquid temperature at 60 ° C. and stirring at 500 rpm.
　反応後、反応容器内に残った溶液を回収した。回収された溶液に対し、洗浄、ろ過、および１２０℃で１２時間の真空乾燥を行った。これにより、正極活物質の前駆体としてのＭｅＣＯ3が得られた。 After the reaction, the solution remaining in the reaction vessel was recovered. The recovered solution was washed, filtered and vacuum dried at 120 ° C. for 12 hours. As a result, MeCO 3 as a precursor of the positive electrode active material was obtained.
　得られた上記前駆体とＬｉ2ＣＯ3とＬｉＦとを、Ｌｉ／Ｍｎ／Ｃｏ／Ｎｉ／Ｏ／Ｆ＝１．２／０．５４／０．１３／０．１３／１．９／０．１のモル比となるようにそれぞれ秤量した。 The obtained precursor, Li 2 CO 3 and Li F were mixed with Li / Mn / Co / Ni / O / F = 1.2 / 0.54 / 0.13 / 0.13 / 1.9 / 0. Each was weighed so as to have a molar ratio of 1.
　次に、得られた混合物を、７００℃で１０時間、大気雰囲気において熱処理した。これにより、リチウム複合酸化物が得られた。このリチウム複合酸化物を、実施例１の正極活物質とした。 Next, the obtained mixture was heat-treated at 700 ° C. for 10 hours in an air atmosphere. As a result, a lithium composite oxide was obtained. This lithium composite oxide was used as the positive electrode active material of Example 1.
　得られた正極活物質に対して、粉末Ｘ線回折測定を実施した。 Powder X-ray diffraction measurement was performed on the obtained positive electrode active material.
　得られた正極活物質は、空間群Ｃ２／ｍに属する結晶構造を有していた。 The obtained positive electrode active material had a crystal structure belonging to the space group C2 / m.
　原料のモル比から求められる実施例１のリチウム複合酸化物の平均組成は、表１に示されているように、Ｌｉ1.2Ｍｎ0.54Ｃｏ0.13Ｎｉ0.13Ｏ1.9Ｆ0.1で表される。 As shown in Table 1, the average composition of the lithium composite oxide of Example 1 determined from the molar ratio of the raw materials is represented by Li 1.2 Mn 0.54 Co 0.13 Ni 0.13 O 1.9 F 0.1 .
　得られた正極活物質、すなわちリチウム複合酸化物に対して、粒子のＳＴＥＭ断面像および原子分解能像の観察が行われた。図３Ａは、実施例１のリチウム複合酸化物の粒子のＳＴＥＭ断面像である。図３Ｂは、図３Ａに示された領域３０部分の原子分解能像である。 The STEM cross-sectional image and atomic resolution image of the particles were observed for the obtained positive electrode active material, that is, the lithium composite oxide. FIG. 3A is a STEM cross-sectional image of the lithium composite oxide particles of Example 1. FIG. 3B is an atomic resolution image of the region 30 portion shown in FIG. 3A.
　図３ＡのＳＴＥＭ断面像から、実施例１のリチウム複合酸化物の粒子が、当該粒子の中心から表面に向かって放射状に並んだ、複数の柱状の結晶集合体を含んでいることが確認された。さらに、図３Ｂの原子分解能像から、状の結晶集合体において、結晶構造のｃ軸が結晶集合体の長軸方向に配向し、かつ結晶構造のａ軸が結晶集合体の短軸方向に配向していることが確認された。 From the STEM cross-sectional image of FIG. 3A, it was confirmed that the lithium composite oxide particles of Example 1 contained a plurality of columnar crystal aggregates arranged radially from the center of the particles toward the surface. .. Further, from the atomic resolution image of FIG. 3B, in the crystalline crystal aggregate, the c-axis of the crystal structure is oriented in the major axis direction of the crystal aggregate, and the a-axis of the crystal structure is oriented in the minor axis direction of the crystal aggregate. It was confirmed that it was done.
　［電池の作製］
　７０質量部の上述の正極活物質と、２０質量部の導電剤と、１０質量部のポリフッ化ビニリデン（ＰＶＤＦ）と、適量の２－メチルピロリドン（ＮＭＰ）とを、混合した。これにより、正極合剤スラリーを得た。 [Battery production]
70 parts by mass of the above-mentioned positive electrode active material, 20 parts by mass of a conductive agent, 10 parts by mass of polyvinylidene fluoride (PVDF), and an appropriate amount of 2-methylpyrrolidone (NMP) were mixed. As a result, a positive electrode mixture slurry was obtained.
　２０μｍの厚さのアルミニウム箔で形成された正極集電体の片面に、正極合剤スラリーを塗布した。 A positive electrode mixture slurry was applied to one side of a positive electrode current collector formed of an aluminum foil having a thickness of 20 μm.
　正極合剤スラリーを乾燥および圧延することによって、正極活物質層を備えた厚さ６０μｍの正極板を得た。 By drying and rolling the positive electrode mixture slurry, a positive electrode plate having a thickness of 60 μm and having a positive electrode active material layer was obtained.
　得られた正極板を、直径１２．５ｍｍの円形状に打ち抜くことによって、正極を得た。 A positive electrode was obtained by punching the obtained positive electrode plate into a circular shape with a diameter of 12.5 mm.
　また、厚さ３００μｍのリチウム金属箔を、直径１４．０ｍｍの円形状に打ち抜くことによって、負極を得た。 Further, a negative electrode was obtained by punching a lithium metal foil having a thickness of 300 μm into a circular shape having a diameter of 14.0 mm.
　また、フルオロエチレンカーボネート（ＦＥＣ）とエチレンカーボネート（ＥＣ）とエチルメチルカーボネート（ＥＭＣ）とを、１：１：６の体積比で混合して、非水溶媒を得た。 Further, fluoroethylene carbonate (FEC), ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed at a volume ratio of 1: 1: 6 to obtain a non-aqueous solvent.
　この非水溶媒に、ＬｉＰＦ6を、１．０ｍｏｌ／リットルの濃度で、溶解させることによって、非水電解液を得た。 A non-aqueous electrolytic solution was obtained by dissolving LiPF 6 in this non-aqueous solvent at a concentration of 1.0 mol / liter.
　得られた非水電解液を、セパレータ（セルガード社製、品番２３２０、厚さ２５μｍ）に、染み込ませた。当該セパレータは、ポリプロピレン層とポリエチレン層とポリプロピレン層とで形成された、３層セパレータである。 The obtained non-aqueous electrolytic solution was impregnated into a separator (manufactured by Celgard, product number 2320, thickness 25 μm). The separator is a three-layer separator formed of a polypropylene layer, a polyethylene layer, and a polypropylene layer.
　上述の正極と負極とセパレータとを用いて、露点が－５０℃に管理されたドライボックスの中で、ＣＲ２０３２規格のコイン型電池を、作製した。 Using the above-mentioned positive electrode, negative electrode, and separator, a CR2032 standard coin-type battery was manufactured in a dry box with a dew point controlled at −50 ° C.
　＜実施例２～７＞
　上述の実施例１から、反応に供する原料の混合比率を、それぞれ変えた。また、上述の実施例１から、熱処理の条件を、５００～９００℃かつ１０分～１０時間の範囲内で、それぞれ変えた。これら以外は、上述の実施例１と同様にして、実施例２～７の正極活物質を合成した。表１に、実施例２～７の正極活物質であるリチウム複合酸化物の平均組成が示される。さらに、表１に、熱処理温度および熱処理時間も示される。 <Examples 2 to 7>
From Example 1 described above, the mixing ratio of the raw materials to be subjected to the reaction was changed. Further, from Example 1 described above, the heat treatment conditions were changed within the range of 500 to 900 ° C. and 10 minutes to 10 hours. Except for these, the positive electrode active materials of Examples 2 to 7 were synthesized in the same manner as in Example 1 described above. Table 1 shows the average composition of the lithium composite oxide which is the positive electrode active material of Examples 2 to 7. In addition, Table 1 also shows the heat treatment temperature and heat treatment time.
　実施例２～７で得られた正極活物質に対しても、実施例１と同様に、粉末Ｘ線回折測定を実施した。表１に示すように、実施例２～７の正極活物質は、空間群Ｃ２／ｍまたはＲ－３ｍに属する結晶構造を有していた。 The powder X-ray diffraction measurement was also carried out on the positive electrode active materials obtained in Examples 2 to 7 in the same manner as in Example 1. As shown in Table 1, the positive electrode active materials of Examples 2 to 7 had a crystal structure belonging to the space group C2 / m or R-3m.
　また、実施例２～７の正極活物質を用いて、上述の実施例１と同様にして、実施例２～７のコイン型電池を作製した。 Further, using the positive electrode active materials of Examples 2 to 7, coin-type batteries of Examples 2 to 7 were produced in the same manner as in Example 1 described above.
　＜比較例１＞
　公知の共沈法を用いて、（Ｍｎ0.675Ｃｏ0.1625Ｎｉ0.1625）（ＯＨ）2で表される組成を有する化合物を得た。この化合物が、正極活物質の前駆体として用いられた。 <Comparative example 1>
A compound having a composition represented by (Mn 0.675 Co 0.1625 Ni 0.1625 ) (OH) 2 was obtained by using a known coprecipitation method. This compound was used as a precursor for the positive electrode active material.
　得られた上記前駆体とＬｉ2ＣＯ3とＬｉＦとを、Ｌｉ／Ｍｎ／Ｃｏ／Ｎｉ／Ｏ／Ｆ＝１．２／０．５４／０．１３／０．１３／１．９／０．１のモル比となるようにそれぞれ秤量した。 The obtained precursor, Li 2 CO 3 and Li F were mixed with Li / Mn / Co / Ni / O / F = 1.2 / 0.54 / 0.13 / 0.13 / 1.9 / 0. Each was weighed so as to have a molar ratio of 1.
　次に、得られた混合物を、７００℃で１０時間、大気雰囲気において熱処理した。これにより、リチウム複合酸化物が得られた。このリチウム複合酸化物を、比較例１の正極活物質とした。 Next, the obtained mixture was heat-treated at 700 ° C. for 10 hours in an air atmosphere. As a result, a lithium composite oxide was obtained. This lithium composite oxide was used as the positive electrode active material of Comparative Example 1.
　得られた正極活物質に対して、粉末Ｘ線回折測定を実施した。 Powder X-ray diffraction measurement was performed on the obtained positive electrode active material.
　得られた正極活物質の空間群は、Ｃ２／ｍであった。 The space group of the obtained positive electrode active material was C2 / m.
　得られた正極活物質、すなわちリチウム複合酸化物に対して、粒子のＳＥＭ断面像の観察が行われた。図４は、比較例１のリチウム複合酸化物の粒子のＳＥＭ断面像である。 The SEM cross-sectional image of the particles was observed for the obtained positive electrode active material, that is, the lithium composite oxide. FIG. 4 is an SEM cross-sectional image of the lithium composite oxide particles of Comparative Example 1.
　図４のＳＥＭ断面像から、比較例１のリチウム複合酸化物の粒子は、当該粒子の中心から表面に向かって放射状に並んだ柱状の結晶集合体を含んでいなかった。 From the SEM cross-sectional image of FIG. 4, the lithium composite oxide particles of Comparative Example 1 did not contain columnar crystal aggregates arranged radially from the center of the particles toward the surface.
　得られた正極活物質を用いて、上述の実施例１と同様にして、比較例１のコイン型電池を作製した。 Using the obtained positive electrode active material, a coin-type battery of Comparative Example 1 was produced in the same manner as in Example 1 described above.
　＜比較例２および３＞
　上述の比較例１から、反応に供する原料の混合比率を、それぞれ変えた。これ以外は、上述の比較例１と同様にして、比較例２および３の正極活物質を合成した。表１に、比較例２および３の正極活物質の平均組成が示される。 <Comparative Examples 2 and 3>
From Comparative Example 1 described above, the mixing ratio of the raw materials to be subjected to the reaction was changed. Except for this, the positive electrode active materials of Comparative Examples 2 and 3 were synthesized in the same manner as in Comparative Example 1 described above. Table 1 shows the average composition of the positive electrode active materials of Comparative Examples 2 and 3.
　比較例２および３で得られた正極活物質に対しても、比較例１と同様に、粉末Ｘ線回折測定を実施した。表１に示すように、比較例２および３の正極活物質は、空間群Ｃ２／ｍに属する結晶構造を有していた。 The positive electrode active materials obtained in Comparative Examples 2 and 3 were also subjected to powder X-ray diffraction measurement in the same manner as in Comparative Example 1. As shown in Table 1, the positive electrode active materials of Comparative Examples 2 and 3 had a crystal structure belonging to the space group C2 / m.
　また、比較例２および３の正極活物質を用いて、上述の実施例１と同様にして、比較例２および３のコイン型電池を作製した。 Further, using the positive electrode active materials of Comparative Examples 2 and 3, coin-type batteries of Comparative Examples 2 and 3 were produced in the same manner as in Example 1 described above.
　＜電池の評価＞
　正極に対する電流密度を０．５ｍＡ／ｃｍ2に設定し、４．７Ｖの電圧に達するまで、実施例１の電池を充電した。 <Battery evaluation>
The current density with respect to the positive electrode was set to 0.5 mA / cm 2, and the battery of Example 1 was charged until a voltage of 4.7 V was reached.
　その後、放電終止電圧を２．５Ｖに設定し、０．５ｍＡ／ｃｍ2の電流密度で、実施例１の電池を放電させた。 Then, the discharge end voltage was set to 2.5 V, and the battery of Example 1 was discharged at a current density of 0.5 mA / cm 2 .
　実施例１の電池の初回放電容量は、２８３ｍＡｈ／ｇであった。 The initial discharge capacity of the battery of Example 1 was 283 mAh / g.
　実施例２～７および比較例１～３のコイン型電池についても、実施例１と同じ方法で、初回放電容量を測定した。 The initial discharge capacity of the coin-type batteries of Examples 2 to 7 and Comparative Examples 1 to 3 was measured by the same method as in Example 1.
　以上の結果が、表１に示される。 The above results are shown in Table 1.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　リチウム複合酸化物が互いに同じ平均組成を有する実施例１と比較例１、実施例５と比較例２、実施例７と比較例３を、それぞれ比較する。表１に示されるように、実施例１、５、および７の電池の初回放電容量は、それぞれ、比較例１、２、および３の電池の初回放電容量よりも、大きい。この理由としては、実施例１、５、および７の正極活物質においては、比較例１、２、および３と異なり、リチウム複合酸化物の粒子内に柱状の結晶集合体が形成されており、その結晶集合体の短軸方向にａ軸が配向し、かつその結晶集合体の長軸方向にｃ軸が配向しているからであると考えられる。実施例１、５、および７の正極活物質がこのような構造を有することにより、Ｌｉイオンの拡散する距離が短くなり、充放電時の抵抗が下がったと考えられる。このため、同じ組成を有するリチウム複合酸化物が正極活物質として用いられているにも関わらず、実施例１、５、および７の電池の方が、比較例１、２、および３の電池よりも、それぞれ、初回放電容量が大きいと考えられる。 Compare Example 1 and Comparative Example 1, Example 5 and Comparative Example 2, and Example 7 and Comparative Example 3 in which the lithium composite oxides have the same average composition. As shown in Table 1, the initial discharge capacities of the batteries of Examples 1, 5, and 7, respectively, are larger than the initial discharge capacities of the batteries of Comparative Examples 1, 2, and 3, respectively. The reason for this is that in the positive electrode active materials of Examples 1, 5, and 7, unlike Comparative Examples 1, 2, and 3, columnar crystal aggregates are formed in the particles of the lithium composite oxide. It is considered that this is because the a-axis is oriented in the minor axis direction of the crystal aggregate and the c-axis is oriented in the major axis direction of the crystal aggregate. It is considered that the positive electrode active materials of Examples 1, 5 and 7 having such a structure shortens the diffusion distance of Li ions and lowers the resistance during charging and discharging. Therefore, although the lithium composite oxide having the same composition is used as the positive electrode active material, the batteries of Examples 1, 5, and 7 are more than the batteries of Comparative Examples 1, 2, and 3. However, it is considered that the initial discharge capacity is large for each.
　また、表１に示されるように、実施例１の電池の初回放電容量は、実施例２の電池の初回放電容量よりも、大きい。この理由としては、実施例１の正極活物質では、実施例２の正極活物質と比較して、構造の安定化に寄与するＣｏが多い。したがって、実施例１の正極活物質では、充放電時の構造が安定化する。このため、実施例１の電池では、初回放電容量が実施例２の電池よりも増加したと考えられる。 Further, as shown in Table 1, the initial discharge capacity of the battery of Example 1 is larger than the initial discharge capacity of the battery of Example 2. The reason for this is that the positive electrode active material of Example 1 has more Co that contributes to the stabilization of the structure as compared with the positive electrode active material of Example 2. Therefore, in the positive electrode active material of Example 1, the structure during charging and discharging is stabilized. Therefore, it is considered that the initial discharge capacity of the battery of Example 1 is larger than that of the battery of Example 2.
　また、表１に示されるように、実施例１の電池の初回放電容量は、実施例３の電池の初回放電容量よりも、大きい。この理由としては、実施例１の正極活物質では、実施例３の正極活物質と比較して、価数が＋IIであるＮｉが多い。したがって、実施例１の電池では、正極活物質におけるＣｏの価数が安定な＋IIIから低い価数に変化しにくく、正極活物質が安定化する。このため、実施例１の電池では、初回放電容量が実施例３の電池よりも増加したと考えられる。 Further, as shown in Table 1, the initial discharge capacity of the battery of Example 1 is larger than the initial discharge capacity of the battery of Example 3. The reason for this is that the positive electrode active material of Example 1 has a large amount of Ni having a valence of + II as compared with the positive electrode active material of Example 3. Therefore, in the battery of Example 1, the valence of Co in the positive electrode active material is unlikely to change from a stable +III to a low valence, and the positive electrode active material is stabilized. Therefore, it is considered that the initial discharge capacity of the battery of Example 1 is larger than that of the battery of Example 3.
　また、表１に示されるように、実施例１の電池の初回放電容量は、実施例４の電池の初回放電容量よりも、大きい。この理由としては、実施例１の正極活物質では、実施例４の正極活物質と比較して、電気化学的に活性なＣｏおよびＮｉが多い。このため、実施例１の電池では、充放電時に遷移金属のレドックス量が多くなり、初回放電容量が増加したと考えられる。 Further, as shown in Table 1, the initial discharge capacity of the battery of Example 1 is larger than the initial discharge capacity of the battery of Example 4. The reason for this is that the positive electrode active material of Example 1 contains more electrochemically active Co and Ni than the positive electrode active material of Example 4. Therefore, in the battery of Example 1, it is considered that the redox amount of the transition metal increased during charging and discharging, and the initial discharging capacity increased.
　また、表１に示されるように、実施例１の電池の初回放電容量は、実施例５の電池の初回放電容量よりも、大きい。この理由としては、実施例１の正極活物質では、実施例４の正極活物質と比較して、リチウム複合酸化物の組成式におけるｘ/ｙの値が大きい。このため、実施例１の電池では、反応に寄与できるＬｉ量が多くなり、充放電時のＬｉの挿入量および脱離量が増加したと考えられる。 Further, as shown in Table 1, the initial discharge capacity of the battery of Example 1 is larger than the initial discharge capacity of the battery of Example 5. The reason for this is that the positive electrode active material of Example 1 has a larger x / y value in the composition formula of the lithium composite oxide than the positive electrode active material of Example 4. Therefore, in the battery of Example 1, it is considered that the amount of Li that can contribute to the reaction increases, and the amount of Li inserted and removed during charging and discharging increases.
　また、表１に示されるように、実施例５の電池の初回放電容量は、実施例６の電池の初回放電容量よりも、大きい。この理由としては、実施例５の正極活物質では、実施例６の正極活物質と比較して、構造安定化に寄与するＣｏ量が多い。したがって、実施例５の正極活物質では、充放電時の構造が安定化する。このため、実施例５の電池では、初回放電容量が実施例６の電池よりも増加したと考えられる。 Further, as shown in Table 1, the initial discharge capacity of the battery of Example 5 is larger than the initial discharge capacity of the battery of Example 6. The reason for this is that the positive electrode active material of Example 5 has a larger amount of Co that contributes to structural stabilization than the positive electrode active material of Example 6. Therefore, in the positive electrode active material of Example 5, the structure during charging and discharging is stabilized. Therefore, it is considered that the initial discharge capacity of the battery of Example 5 is larger than that of the battery of Example 6.
　また、表１に示されるように、実施例１の電池の初回放電容量は、実施例７の電池の初回放電容量よりも、大きい。この理由としては、実施例１の正極活物質では、実施例７の正極活物質と比較して、初期の遷移金属の価数が大きい。このため、実施例１の正極活物質では、充電の際に酸素の電荷補償量が大きくなりすぎず、充電時の構造が安定化したと考えられる。このため、実施例１の電池では、初回放電容量が実施例７の電池よりも増加したと考えられる。 Further, as shown in Table 1, the initial discharge capacity of the battery of Example 1 is larger than the initial discharge capacity of the battery of Example 7. The reason for this is that the positive electrode active material of Example 1 has a higher valence of the initial transition metal than the positive electrode active material of Example 7. Therefore, it is considered that the positive electrode active material of Example 1 does not have an excessively large amount of oxygen charge compensation during charging, and the structure during charging is stabilized. Therefore, it is considered that the initial discharge capacity of the battery of Example 1 is larger than that of the battery of Example 7.
　本開示の正極活物質は、二次電池などの電池の正極活物質として、利用されうる。 The positive electrode active material of the present disclosure can be used as a positive electrode active material of a battery such as a secondary battery.
　１　　リチウム複合酸化物の粒子
　２　　柱状の結晶集合体
　３　　柱状の結晶集合体の長軸方向
　４　　柱状の結晶集合体の短軸方向
　１０　電池
　１１　ケース
　１２　正極集電体
　１３　正極活物質層
　１４　セパレータ
　１５　封口板
　１６　負極集電体
　１７　負極活物質層
　１８　ガスケット
　２１　正極
　２２　負極 1 Lithium composite oxide particles 2 Columnar crystal aggregate 3 Major axis direction of columnar crystal aggregate 4 Short axis direction of columnar crystal aggregate 10 Battery 11 Case 12 Positive electrode current collector 13 Positive electrode active material layer 14 Separator 15 Seal plate 16 Negative electrode current collector 17 Negative electrode active material layer 18 Gasket 21 Positive electrode 22 Negative electrode

Claims (19)

  1. 　層状構造に属する結晶構造を有するリチウム複合酸化物の粒子を含み、
    　前記粒子は、当該粒子の中心から表面に向かって放射状に並んだ、複数の柱状の結晶集合体を含み、
    　前記柱状の結晶集合体において、前記結晶構造のｃ軸が前記結晶集合体の長軸方向に配向し、かつ前記結晶構造のａ軸が前記結晶集合体の短軸方向に配向している、
    正極活物質。     Contains particles of lithium composite oxide having a crystal structure belonging to a layered structure,
    The particles include a plurality of columnar crystal aggregates arranged radially from the center of the particles toward the surface.
    In the columnar crystal aggregate, the c-axis of the crystal structure is oriented in the major axis direction of the crystal aggregate, and the a-axis of the crystal structure is oriented in the minor axis direction of the crystal aggregate.
    Positive electrode active material.
  2. 　前記柱状の結晶集合体の短軸の長さをＸｎｍとしたとき、Ｘは、１０＜Ｘ＜５００を満たす、
    請求項１に記載の正極活物質。     When the length of the minor axis of the columnar crystal aggregate is X nm, X satisfies 10 <X <500.
    The positive electrode active material according to claim 1.
  3. 　前記柱状の結晶集合体の短軸の長さをＸｎｍとしたとき、Ｘは、２０＜Ｘ＜２５０を満たす、
    請求項２に記載の正極活物質。     When the length of the minor axis of the columnar crystal aggregate is X nm, X satisfies 20 <X <250.
    The positive electrode active material according to claim 2.
  4. 　前記結晶構造は、空間群Ｃ２／ｍおよび空間群Ｒ－３ｍからなる群より選択される少なくとも１つに属する、
    請求項１から３のいずれか一項に記載の正極活物質。     The crystal structure belongs to at least one selected from the group consisting of the space group C2 / m and the space group R-3m.
    The positive electrode active material according to any one of claims 1 to 3.
  5. 　前記粒子が、内部に、空隙層を有する、
    請求項１から４のいずれか一項に記載の正極活物質。     The particles have a void layer inside.
    The positive electrode active material according to any one of claims 1 to 4.
  6. 　前記リチウム複合酸化物の平均組成は、下記の組成式（１）で表される、
    請求項１から５のいずれか一項に記載の正極活物質。
    　ＬｉxＭｅyＯαＱβ　・・・式（１）
    　ここで、
    　前記Ｍｅは、Ｍｎ、Ｃｏ、Ｎｉ、Ｆｅ、Ｃｕ、Ｖ、Ｎｂ、Ｍｏ、Ｔｉ、Ｃｒ、Ｚｒ、Ｚｎ、Ｎａ、Ｋ、Ｃａ、Ｍｇ、Ｐｔ、Ａｕ、Ａｇ、Ｒｕ、Ｗ、Ｂ、Ｓｉ、Ｐ、およびＡｌからなる群より選択される少なくとも１種であり、
    　前記Ｑは、Ｆ、Ｃｌ、Ｎ、およびＳからなる群より選択される少なくとも１種であり、かつ、
    　前記組成式（１）は、下記の条件
    １．０５≦ｘ≦１．５、
    ０．６≦ｙ≦１．０、
    １．２≦α≦２．０、および
    ０＜β≦０．８
    を満たす。     The average composition of the lithium composite oxide is represented by the following composition formula (1).
    The positive electrode active material according to any one of claims 1 to 5.
    Li x Me y O α Q β ··· formula (1)
    here,
    The Me is Mn, Co, Ni, Fe, Cu, V, Nb, Mo, Ti, Cr, Zr, Zn, Na, K, Ca, Mg, Pt, Au, Ag, Ru, W, B, Si, At least one selected from the group consisting of P and Al,
    The Q is at least one selected from the group consisting of F, Cl, N, and S, and is
    The composition formula (1) is based on the following conditions: 1.05 ≦ x ≦ 1.5,
    0.6 ≤ y ≤ 1.0,
    1.2 ≤ α ≤ 2.0 and 0 <β ≤ 0.8
    Meet.
  7. 　前記Ｍｅは、Ｍｎ、Ｃｏ、Ｎｉ、Ｆｅ、Ｃｕ、Ｖ、Ｔｉ、Ｃｒ、およびＺｎからなる群より選択される少なくとも１種を含む、
    請求項６に記載の正極活物質。     The Me contains at least one selected from the group consisting of Mn, Co, Ni, Fe, Cu, V, Ti, Cr, and Zn.
    The positive electrode active material according to claim 6.
  8. 　前記Ｍｅは、Ｍｎ、Ｃｏ、Ｎｉ、およびＡｌからなる群より選択される少なくとも１種を含む、
    請求項６または７に記載の正極活物質。     The Me contains at least one selected from the group consisting of Mn, Co, Ni, and Al.
    The positive electrode active material according to claim 6 or 7.
  9. 　前記Ｍｅは、Ｍｎを含む、
    請求項７または８に記載の正極活物質。     The Me contains Mn,
    The positive electrode active material according to claim 7 or 8.
  10. 　前記Ｍｅに対する前記Ｍｎの割合が、５９．９モル％以上である、
    請求項９に記載の正極活物質。     The ratio of the Mn to the Me is 59.9 mol% or more.
    The positive electrode active material according to claim 9.
  11. 　前記Ｑは、Ｆを含む、
    請求項６から１０のいずれか一項に記載の正極活物質。     The Q includes F.
    The positive electrode active material according to any one of claims 6 to 10.
  12. 　前記組成式（１）は、下記の条件
    　１．１６６≦ｘ≦１．２３、および
    　０．７７≦ｙ≦０．８３４、
    を満たす、
    請求項６から１１のいずれか一項に記載の正極活物質。     The composition formula (1) has the following conditions: 1.166 ≦ x ≦ 1.23, and 0.77 ≦ y ≦ 0.834.
    Meet,
    The positive electrode active material according to any one of claims 6 to 11.
  13. 　前記組成式（１）は、下記の条件
    　１．９≦α≦１．９１７、および
    　０．０８３≦β≦０．１、
    を満たす、
    請求項６から１２のいずれか一項に記載の正極活物質。     The composition formula (1) has the following conditions: 1.9 ≤ α ≤ 1.917 and 0.083 ≤ β ≤ 0.1.
    Meet,
    The positive electrode active material according to any one of claims 6 to 12.
  14. 　前記組成式（１）は、下記の条件
    　１．３９≦ｘ／ｙ≦１．６、
    を満たす、
    請求項６から１３のいずれか一項に記載の正極活物質。     The composition formula (1) is based on the following conditions: 1.39 ≦ x / y ≦ 1.6,
    Meet,
    The positive electrode active material according to any one of claims 6 to 13.
  15. 　前記組成式（１）は、下記の条件
    　１９≦α／β≦２３．１、
    を満たす、
    請求項６から１４のいずれか一項に記載正極活物質。     The composition formula (1) is based on the following conditions 19 ≦ α / β ≦ 23.1.
    Meet,
    The positive electrode active material according to any one of claims 6 to 14.
  16. 　前記リチウム複合酸化物の粒子を、主成分として含む、
    請求項１から１５のいずれか一項に記載の正極活物質。     The lithium composite oxide particles are contained as a main component.
    The positive electrode active material according to any one of claims 1 to 15.
  17. 　請求項１から１６のいずれか一項に記載の正極活物質を含む正極と、
    　負極と、
    　電解質と、を備える、
    電池。     A positive electrode containing the positive electrode active material according to any one of claims 1 to 16.
    With the negative electrode
    With electrolyte,
    battery.
  18. 　前記負極は、リチウムイオンを吸蔵および放出しうる負極活物質、または、リチウム金属を負極活物質として溶解および析出させうる材料を含み、
    　前記電解質は、非水電解液である、
    請求項１７に記載の電池。     The negative electrode contains a negative electrode active material capable of occluding and releasing lithium ions, or a material capable of dissolving and precipitating lithium metal as a negative electrode active material.
    The electrolyte is a non-aqueous electrolyte solution.
    The battery according to claim 17.
  19. 　前記負極は、リチウムイオンを吸蔵および放出しうる負極活物質、または、リチウム金属を負極活物質として溶解および析出させうる材料を含み、
    　前記電解質は、固体電解質である、
    請求項１７に記載の電池。     The negative electrode contains a negative electrode active material capable of occluding and releasing lithium ions, or a material capable of dissolving and precipitating lithium metal as a negative electrode active material.
    The electrolyte is a solid electrolyte.
    The battery according to claim 17.
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