WO2012164693A1 - リチウム二次電池 - Google Patents
リチウム二次電池 Download PDFInfo
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- WO2012164693A1 WO2012164693A1 PCT/JP2011/062525 JP2011062525W WO2012164693A1 WO 2012164693 A1 WO2012164693 A1 WO 2012164693A1 JP 2011062525 W JP2011062525 W JP 2011062525W WO 2012164693 A1 WO2012164693 A1 WO 2012164693A1
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
- C01D15/00—Lithium compounds
- C01D15/02—Oxides; Hydroxides
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- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G53/00—Compounds of nickel
- C01G53/40—Nickelates
- C01G53/42—Nickelates containing alkali metals, e.g. LiNiO2
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G53/00—Compounds of nickel
- C01G53/40—Nickelates
- C01G53/42—Nickelates containing alkali metals, e.g. LiNiO2
- C01G53/44—Nickelates containing alkali metals, e.g. LiNiO2 containing manganese
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- 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
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/362—Composites
- H01M4/366—Composites as layered products
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
- H01M4/46—Alloys based on magnesium or aluminium
- H01M4/466—Magnesium based
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/48—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
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/48—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
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2002/00—Crystal-structural characteristics
- C01P2002/50—Solid solutions
- C01P2002/52—Solid solutions containing elements as dopants
- C01P2002/54—Solid solutions containing elements as dopants one element only
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/12—Surface area
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/40—Electric properties
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/80—Compositional purity
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- 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
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
Definitions
- the present invention relates to a lithium secondary battery using a lithium transition metal oxide as a positive electrode active material and a positive electrode active material for the battery.
- Lithium secondary batteries are becoming increasingly important as on-vehicle power supplies or personal computers and mobile terminals.
- a lithium ion secondary battery that is lightweight and obtains a high energy density is expected to be suitable as a high-output power source mounted on a vehicle.
- a positive electrode active material used for a lithium secondary battery a composite oxide containing lithium (Li) and at least one transition metal element (hereinafter also referred to as lithium transition metal oxide) can be given.
- Patent Documents 1 to 3 are cited as technical documents related to lithium secondary batteries.
- the output of a lithium secondary battery decreases as the SOC (state of charge) decreases. If the output in the low SOC region can be improved, a desired output can be obtained in a wider SOC range, and the amount of energy that can be effectively utilized by taking out the unit volume or unit mass of the battery increases. This is particularly significant in, for example, a vehicle-mounted battery (for example, a vehicle drive power source) that requires high output and high energy density.
- a vehicle-mounted battery for example, a vehicle drive power source
- One object of the present invention is to provide a lithium secondary battery excellent in output in a low SOC region. Another related object is to provide a method for producing such a positive electrode active material for a lithium secondary battery.
- a lithium secondary battery including a positive electrode, a negative electrode, and a nonaqueous electrolyte.
- the positive electrode has a positive electrode active material in the form of secondary particles in which primary particles of lithium transition metal oxide are collected.
- the positive electrode active material includes at least one of nickel (Ni), cobalt (Co), and manganese (Mn).
- the positive electrode active material further contains tungsten (W) and magnesium (Mg). The W exists in a biased manner on the surface of the primary particles (which can also be grasped as a grain boundary).
- the Mg is present throughout the primary particles.
- the content of Mg in the positive electrode active material is an amount exceeding 50 ppm with respect to the total amount of the active material on a mass basis.
- the lithium secondary battery having such a configuration is excellent in output in a low SOC region due to a synergistic effect of W present in the surface of the primary particles of the positive electrode active material and Mg present in the entire interior of the primary particles. Can be.
- the range in which a desired output can be obtained extends to the low SOC side, so that the lithium secondary battery can be effectively used in a wider SOC range.
- the Mg content more than 50 ppm (for example, 100 ppm or more), the output improvement effect in the low SOC region can be more reliably exhibited.
- the “lithium secondary battery” refers to a secondary battery that uses lithium ions as electrolyte ions and is charged / discharged by the movement of charges accompanying the lithium ions between the positive and negative electrodes.
- a battery generally called a lithium ion secondary battery is a typical example included in the lithium secondary battery in this specification.
- the “active material” can reversibly occlude and release (typically insertion and desorption) chemical species (that is, lithium ions here) that serve as charge carriers in the secondary battery.
- SOC refers to a state of charge of a battery based on a voltage range in which the battery is normally used unless otherwise specified.
- a rated capacity (typically measured under conditions of a terminal voltage of 4.1 V (upper limit voltage) to 3.0 V (lower limit voltage)) refers to the state of charge based on the rated capacity specified under the same conditions as the rated capacity measurement of the evaluation test battery described later.
- the content of Mg in the positive electrode active material is preferably 1000 ppm or less (for example, 100 ppm or more and 800 ppm or less) with respect to the total amount of the positive electrode active material on a mass basis. If the Mg content is too high, the output in the moderate SOC region (for example, output at ⁇ 30 ° C.) may tend to decrease.
- the content of W in the positive electrode active material is preferably 0.05 mol% or more and 2 mol% or less, where the total amount of Ni, Co and Mn contained in the positive electrode active material is 100 mol%. According to the positive electrode active material having such a composition, a battery with higher performance can be realized.
- the lithium transition metal oxide is an oxide having a layered structure containing at least Ni as a constituent metal element.
- a lithium transition metal oxide containing all of Ni, Co, and Mn as constituent metal elements (hereinafter also referred to as “LiNiCoMn oxide”) having a layered structure is preferable.
- LiNiCoMn oxide a lithium transition metal oxide containing all of Ni, Co, and Mn as constituent metal elements
- a positive electrode active material for a lithium secondary battery which is a secondary particle in which primary particles of a lithium transition metal oxide (typically, a lithium transition metal oxide having a layered structure) are collected.
- a method for producing a positive electrode active material containing at least one of Ni, Co, and Mn, and further containing W and Mg includes preparing an aqueous solution (typically an acidic aqueous solution) Aq A containing at least one of Ni, Co, and Mn and Mg.
- the method includes preparing an aqueous solution Aq C containing W.
- the aqueous solution Aq A and the aqueous solution Aq C are mixed under alkaline conditions to precipitate a hydroxide containing at least one of Ni, Co, and Mn, Mg, and W.
- This method typically further comprises mixing the hydroxide and a lithium compound.
- the method may include firing the mixture to form the lithium transition metal oxide.
- an aqueous solution Aq A containing at least one of Ni, Co and Mn and Mg and an aqueous solution Aq C containing W are prepared as separate aqueous solutions, And the aqueous solution Aq A and the aqueous solution Aq C are mixed under alkaline conditions (that is, under conditions where the pH exceeds 7), and a hydroxide containing at least one of Ni, Co and Mn, Mg and W (hereinafter referred to as “hydroxide”) , Also referred to as “precursor hydroxide”). Then, this precursor hydroxide is mixed with a lithium compound (Li source) and fired.
- a lithium compound Li source
- Such a method is in the form of secondary particles in which primary particles of lithium transition metal oxide are collected, Mg is present in the entire interior of the primary particles, and W is present on the surface of the primary particles. It is suitable as a method for producing Therefore, the above method includes the production of any positive electrode active material disclosed herein, the production of a positive electrode for a lithium secondary battery provided with the positive electrode active material, the production of a lithium secondary battery provided with the positive electrode active material, etc. It can be preferably applied.
- the precipitation of the precursor hydroxide is preferably performed while maintaining the pH at 11 to 14 (eg, pH 11.5 to 12.5, typically around pH 12).
- the pH value in this specification refers to a pH value based on a liquid temperature of 25 ° C. unless otherwise specified.
- an alkaline aqueous solution is prepared separately from the aqueous solution Aq A and the aqueous solution Aq C , and the alkaline condition is maintained using the alkaline aqueous solution (for example, a pH of 11 to 11). 14).
- the alkaline aqueous solution an aqueous solution containing at least ammonia can be preferably used.
- an aspect in which a mixed solution of ammonia water and sodium hydroxide aqueous solution is used as the alkaline aqueous solution.
- Another preferred embodiment is a mode in which two or more types of alkaline aqueous solutions (for example, aqueous ammonia and aqueous sodium hydroxide) are used separately (for example, each alkaline aqueous solution is supplied to the reaction tank independently). . You may combine these aspects.
- two or more types of alkaline aqueous solutions for example, aqueous ammonia and aqueous sodium hydroxide
- each alkaline aqueous solution is supplied to the reaction tank independently.
- a positive electrode active material produced by any of the methods disclosed herein is provided.
- a positive electrode for a lithium secondary battery provided with the positive electrode active material disclosed herein (which can be a positive electrode active material produced by any of the methods disclosed herein).
- a lithium secondary battery including such a positive electrode is provided.
- the lithium secondary battery disclosed herein (typically, a lithium ion secondary battery) can provide a good output even in a low SOC region. Can be suitably used. Therefore, as another aspect of the present invention, for example, as shown in FIG. 8, any of the lithium secondary batteries 100 disclosed herein (a form of an assembled battery in which a plurality of batteries are typically connected in series)
- a vehicle 1 provided with
- a vehicle for example, an automobile
- a lithium secondary battery as a power source typically, a power source of a hybrid vehicle or an electric vehicle
- a lithium secondary battery 100 for a vehicle driving power source is provided.
- FIG. 1 is a flowchart showing an outline of a method for producing a positive electrode active material according to an embodiment.
- FIG. 2 is a perspective view schematically showing a configuration example of the lithium secondary battery.
- 3 is a cross-sectional view taken along line III-III in FIG.
- FIG. 4 is a TEM image of the positive electrode active material according to an embodiment.
- FIG. 5 is an image showing the distribution of W in the positive electrode active material shown in FIG. 6 is an image showing the distribution of Mg in the positive electrode active material shown in FIG.
- FIG. 7 is a characteristic diagram showing an X-ray absorption fine structure spectrum of W in the positive electrode active material according to one embodiment.
- FIG. 8 is a side view schematically showing a vehicle (automobile) equipped with a lithium secondary battery.
- the positive electrode active material in the technology disclosed herein is in the form of secondary particles in which primary particles of lithium transition metal oxide are collected.
- the lithium transition metal oxide is a lithium oxide containing at least one of Ni, Co, and Mn.
- the crystal structure may be layered, spinel type, or the like.
- the lithium transition metal oxide has a layered (typically rock salt type) crystal structure.
- the technology disclosed herein is applied to a positive electrode for a lithium secondary battery provided with such a positive electrode active material, and various lithium secondary batteries (typically lithium ion secondary batteries) having the positive electrode as a constituent element. Can be done.
- the total content of Ni, Co, and Mn in the positive electrode active material is, for example, 85 mol% or more (preferably 90 mol% or more, preferably 100 mol%), with the total amount of metal elements other than lithium contained in the positive electrode active material being 100 mol%. Typically 95 mol% or more).
- a positive electrode active material containing at least Ni is preferable.
- An active material is preferred.
- the lithium transition metal oxide in the technology disclosed herein there is a lithium oxide containing at least Li, Ni, Co, and Mn (that is, LiNiCoMn oxide).
- the total amount (based on the number of atoms) of Ni, Co and Mn is 1, the amounts of Ni, Co and Mn all exceed 0 and not more than 0.7 (for example, more than 0.1 and not more than 0.6) LiNiCoMn oxide that is typically more than 0.3 and 0.5 or less can be preferably used.
- the first element of Ni, Co, and Mn (the element that is contained most on the basis of the number of atoms) may be any of Ni, Co, and Mn. In a preferred embodiment, the first element is Ni. In another preferred embodiment, the amounts of Ni, Co and Mn (based on the number of atoms) are approximately the same.
- Such a ternary lithium transition metal oxide is preferable because it exhibits excellent thermal stability as a positive electrode active material.
- the positive electrode active material contains at least one of Ni, Co, and Mn, and further contains W and Mg.
- One feature of the technique disclosed here is that the Mg is present in the entire interior of the primary particles, while the W is biased to the surface of the primary particles. By distributing W and Mg in this way, it is possible to realize a lithium secondary battery in which the output in the low SOC region (particularly the low temperature output) is effectively improved.
- W is “biased on the surface of the primary particles” means that W is present (distributed) concentrated on the surface (grain boundaries) of the primary particles compared to the inside of the primary particles. means. Therefore, it does not mean only an aspect in which W exists only at the grain boundary (in other words, does not exist at all inside the primary particle).
- the presence of W on the surface of primary particles is, for example, the distribution of W using energy dispersive X-ray spectroscopy (EDX; Energy Dispersive X-ray Spectroscopy) for active material particles (secondary particles).
- EDX Energy Dispersive X-ray Spectroscopy
- W is concentrated on the grain boundary (the amount of W present per area at the grain boundary is larger than that in the primary particle). (See FIG. 5).
- the position of the grain boundary (primary particle surface) can be grasped by, for example, observation of the cross section with a transmission electron microscope (TEM).
- TEM transmission electron microscope
- Mg is present in the entire interior of the primary particles
- Mg is present (distributed) in the entire positive electrode active material without showing any noticeable bias (preferably substantially uniformly). To do. Therefore, in contrast to the W distribution, there is no bias toward the primary particle surface in Mg.
- the fact that there is no bias in the distribution of Mg can be recognized, for example, by analyzing the line of active material particles (secondary particles) with EDX and not concentrating them at positions corresponding to the grain boundaries. It can also be grasped by mapping the Mg distribution in the same manner as in the case of W and no concentration at the grain boundary is observed (see FIG. 6). In a preferred embodiment, the result of the line analysis is substantially uniform throughout the interior of the primary particles (eg, throughout the active material particles).
- the positive electrode active material contains at least one of Ni, Co, and Mn (typically, it is included as a constituent metal element of the lithium transition metal oxide). It is preferable that it exists in the whole inside (preferably substantially uniformly).
- the positive electrode active material can contain one or more metal elements in addition to the metal elements described above (that is, at least one of Ni, Co, and Mn, Li, W, and Mg).
- metal elements are, for example, one or more elements selected from Al, Cr, Fe, V, Nb, Mo, Ti, Cu, Zn, Ga, In, Sn, La, Ce, Ca, and Na. possible.
- Each distribution of such an arbitrary metal element is not particularly limited. For example, it may be present on the surface of the primary particle in a biased manner, or may exist in the entire interior of the primary particle.
- Such an arbitrary metal element can bring about an effect of reducing the reaction resistance of the battery or improving the durability at a high temperature.
- each arbitrary metal element in the case where two or more kinds are included, each content
- the content of each arbitrary metal element is 1 mol% or less of the total amount of all metal elements other than Li (typically May be less than 1 mol%), and is usually preferably 0.1 mol% or less (typically less than 0.1 mol%).
- the total amount of these optional metal elements should be 2 mol% or less (typically less than 2 mol%) of the total amount of all metal elements other than Li. Usually, it is preferably 0.2 mol% or less (typically less than 0.2 mol%).
- Li, Ni, Co, Mn, W, Mg Li, Ni, Co, Mn, W, Mg
- Lithium transition metal oxides may also be used.
- the positive electrode active material may be, for example, a material having a composition excluding W and Mg (referring to an average composition of the entire positive electrode active material) represented by the following formula (I).
- m may be 0 ⁇ m ⁇ 0.2 (for example, 0.05 ⁇ x ⁇ 0.2).
- P in the above formula may be 0.1 ⁇ p ⁇ 1 (for example, 0.3 ⁇ p ⁇ 0.9, preferably 0.3 ⁇ p ⁇ 0.6).
- q may be 0 ⁇ q ⁇ 0.5 (for example, 0.1 ⁇ q ⁇ 0.4, preferably 0.3 ⁇ q ⁇ 0.6).
- r may be 0 ⁇ r ⁇ 0.5 (eg, 0.1 ⁇ r ⁇ 0.4, preferably 0.3 ⁇ r ⁇ 0.6).
- p + q + r ⁇ 1 (typically 0.8 ⁇ p + q + r ⁇ 1, for example, 0.9 ⁇ p + q + r ⁇ 1).
- M 1 may be one or more selected from Al, Cr, Fe, V, Ti, Mo, Cu, Zn, Ga, In, Sn, La, Ce, Ca, and Na.
- s may be 0 ⁇ s ⁇ 0.05.
- s may be substantially 0 (that is, an oxide that does not substantially contain M 1 ).
- a positive electrode active material having an average composition in which predetermined amounts of W and Mg are added to the composition represented by the above formula (I) is preferable.
- the said Formula (I) points out the composition remove
- the content of W in the positive electrode active material is, for example, more than 0 mol% and not more than 3 mol%, where the total amount of Ni, Co and Mn contained in the positive electrode active material is 100 mol%. It can be. If the W content is too small, the battery performance improvement effect (for example, the effect of improving the output in the low SOC region, the effect of reducing the reaction resistance, etc.) with respect to the positive electrode active material having a composition not containing W is hardly exhibited. It can be. In addition, when the amount of W is too large, the effect of improving the battery performance with respect to the composition containing no W may not be sufficiently exhibited, or the battery performance may be deteriorated.
- the battery performance improvement effect for example, the effect of improving the output in the low SOC region, the effect of reducing the reaction resistance, etc.
- the W content is 0.05 mol% or more and 2 mol% or less (for example, 0.1 mol% or more and 1.0 mol% or less).
- W is concentrated at a position suitable for performing a desired function (specifically, the surface of the primary particle), so even a smaller amount of W is sufficient. A significant performance improvement effect can be exhibited. Therefore, adverse effects (contradictions) associated with the use of W can be better suppressed. It is also advantageous from the viewpoint of reducing the resource risk of battery materials.
- the W content can be measured, for example, by ICP (Inductively Coupled Plasma) emission analysis.
- the content of Mg in the positive electrode active material is preferably an amount exceeding 50 ppm relative to the total amount of the positive electrode active material on a mass basis. That is, it is preferable to contain more than 50 / (1 million) g of Mg per 1 g of the positive electrode active material. If the content of Mg is too small, the battery performance improvement effect (for example, the effect of improving the output in the low SOC region) with respect to the positive electrode active material having a composition not containing Mg may not be sufficiently exhibited. In a preferred embodiment, the Mg content is 1000 ppm or less. If the Mg content is too high, the output in a moderate SOC region (typically about 40 to 60% SOC, for example 56%) may decrease.
- the Mg content is set to 100 ppm to 800 ppm (for example, 300 ppm to 600 ppm).
- the Mg content can be measured by, for example, ICP emission analysis.
- the output in the low SOC region is improved by using the positive electrode active material having the above-described configuration, but for example, the following inference can be made. . That is, as one method for improving the output in the low SOC region, it is conceivable to reduce the discharge depth of the positive electrode in the low SOC region.
- the shallow depth of discharge of the positive electrode means that the amount of Li ions that can be accepted by the positive electrode active material in a predetermined SOC is large with respect to the SOC of the battery (a large margin for accepting Li ions).
- the mobility (diffusibility) of Li in the solid of the positive electrode active material tends to increase. Therefore, it is expected that the output in the low SOC region (particularly, the low temperature output that is easily affected by the diffusibility of Li) can be improved by reducing the discharge depth of the positive electrode in the low SOC region.
- W present on the surface (particle interface) of the primary particles helps to improve the initial charge / discharge efficiency by, for example, contributing to charge / discharge of the battery due to its own valence change. obtain. This W can also exhibit the effect of reducing the reaction resistance of the positive electrode active material.
- Mg present in the primary particles can help to improve the initial charge / discharge efficiency by stabilizing the crystal structure change due to charge / discharge.
- a method for producing such a positive electrode active material a method capable of preparing the active material as a final product can be appropriately employed.
- the lithium transition metal oxide is mainly a layered structure oxide (LiNiCoMn oxide) containing all of Ni, Co and Mn will be described.
- the embodiment will be described in more detail, it is not intended to limit the application target of the technology disclosed herein to such a positive electrode active material.
- the positive electrode active material manufacturing method includes preparing an aqueous solution (typically acidic, ie, an aqueous solution having a pH of less than 7) Aq A containing Ni, Co, Mn, and Mg. (Step S110).
- This aqueous solution Aq A is typically a composition that is substantially free of W.
- the amount ratio of each metal element contained in the aqueous solution Aq A can be appropriately set according to the composition of the positive electrode active material that is the object. For example, the molar ratio of Ni, Co, and Mn can be approximately the same as the molar ratio of these elements in the positive electrode active material.
- the Mg content in the positive electrode active material can be adjusted by adjusting the Mg concentration in the aqueous solution Aq A.
- the aqueous solution Aq A may be one type of aqueous solution containing all of Ni, Co, Mn, and Mg, or two or more types of aqueous solutions having different compositions.
- two types of aqueous solutions Aq A1 containing only Ni, Co and Mn as metal elements and aqueous solutions Aq A2 containing only Mg as metal elements may be used as the Aq A.
- Ni, Co can be preferably used a mode of using one kind of aqueous solution Aq A containing all Mn and Mg.
- the aqueous solution Aq A can be prepared, for example, by dissolving a predetermined amount of each of an appropriate Ni compound, Co compound, Mn compound, and Mg compound in an aqueous solvent.
- an appropriate Ni compound, Co compound, Mn compound, and Mg compound in an aqueous solvent.
- salts of each metal that is, Ni salt, Co salt, Mn salt, and Mg salt
- the order in which these metal salts are added to the aqueous solvent is not particularly limited.
- Ni salt, Co salt, Mn salt, Mg salt sulfate ion, nitrate ion, chloride ion, carbonate ion, hydroxide ion, and the like.
- the metal salts may be Ni, Co, Mn, Mg sulfates, nitrates, hydrochlorides, carbonates, hydroxides, and the like. All or part of these metal salt anions may be the same or different from each other.
- Each of these salts may be a solvate such as a hydrate.
- the concentration of the aqueous solution Aq A is preferably such that the total of all transition metals (Ni, Co, Mn) is about 1.0 to 2.2 mol / L.
- the positive electrode active material manufacturing method also includes preparing an aqueous solution Aq C containing W (hereinafter also referred to as “W aqueous solution”) (step S120).
- This aqueous W solution is typically substantially free of Ni, Co, Mn, and Mg (which means that these metal elements are at least not intentionally contained, and is allowed to be mixed as an inevitable impurity).
- A) composition for example, a W aqueous solution containing substantially only W as a metal element can be preferably used.
- the aqueous W solution can be prepared by dissolving a predetermined amount of a W compound in an aqueous solvent, similar to the aqueous solution Aq A described above.
- a W compound for example, various W salts can be used.
- a salt of tungstic acid an oxo acid having W as a central element
- the cation in the W salt can be selected so that the salt is water-soluble, and may be, for example, ammonium ion, sodium ion, potassium ion, or the like.
- An example of a W salt that can be preferably used is ammonium paratungstate (5 (NH 4 ) 2 O ⁇ 12WO 3 ) (FIG. 1).
- the W salt may be a solvate such as a hydrate.
- the concentration of the aqueous W solution is preferably about 0.01 to 1 mol / L based on the W element.
- the aqueous solvent used for the preparation of the aqueous solution Aq A and the aqueous W solution is typically water.
- water containing a reagent (acid, base, etc.) that improves solubility may be used.
- the method according to this aspect may further include providing an alkaline aqueous solution (step S130).
- This alkaline aqueous solution is an aqueous solution in which an alkaline agent (a compound having an action of tilting the liquid property toward the alkali side) is dissolved in an aqueous solvent.
- an alkaline agent a compound having an action of tilting the liquid property toward the alkali side
- an alkali agent any of strong bases (for example, alkali metal hydroxides such as sodium hydroxide and potassium hydroxide) and weak bases (ammonia, amine, etc.) can be used.
- Alkaline aqueous solution Aq B containing at least ammonia is preferred.
- an alkaline aqueous solution containing both a weak base and a strong base is used.
- an alkaline aqueous solution containing ammonia and sodium hydroxide can be preferably used.
- a plurality of alkaline aqueous solutions having different compositions may be used.
- Ni, Co, Mn, Mg, and W are not substantially contained (refers to not containing these metal elements at least intentionally, and mixing as an unavoidable impurity or the like is acceptable. ) Composition.
- aqueous solution Aq A and the aqueous W solution are mixed under alkaline (preferably pH 11 to 14) conditions to precipitate a precursor hydroxide containing Ni, Co, Mn, Mg and W (crystallization).
- alkaline preferably pH 11 to 14
- the aqueous solution Aq A is mixed with W after being neutralized.
- an alkaline aqueous solution having an initial pH of 11 to 14 typically 11.5 to 12.5, for example, about 12.0
- Aqueous solution Aq A and aqueous W solution Aq C are supplied to the reaction vessel at an appropriate rate and mixed with stirring.
- an alkaline aqueous solution may be additionally supplied to the reaction vessel as necessary (step S144).
- the precipitated precursor hydroxide is preferably washed and filtered, dried after crystallization, and prepared into particles having a desired particle size (step S150).
- primary particles are prepared by preparing Ni, Co, Mn, Mg, and W in separate aqueous solutions and mixing them under alkaline conditions (typically, pH 11 or higher).
- Precursor hydroxide (typically in the form of particles) suitable for the production of a positive electrode active material in which Mg is present throughout the interior of the particles and W is present on the surface of the primary particles. This is because the aqueous solution Aq A containing Ni, Co, Mn and Mg is neutralized as described above and then mixed with W, so that a hydroxide containing Ni, Co, Mn and Mg starts to precipitate first. It is considered that W is likely to precipitate by contacting the precipitate.
- the temperature of the reaction liquid can be controlled in the range of 20 ° C. to 60 ° C. (for example, 30 ° C. to 50 ° C.). preferable. Further, it is preferable to adjust the pH of the reaction solution to 11 to 14 (typically 11.5 to 12.5, for example, about 12.0). In an embodiment using an alkaline aqueous solution containing ammonia, it is preferable to adjust the ammonia concentration in the reaction solution to 3 to 25 g / L.
- the time for continuing the precipitation reaction of the precursor hydroxide can be appropriately set according to the particle diameter (typically average particle diameter) of the target positive electrode active material. As a tendency, in order to obtain a positive electrode active material having a larger particle diameter, it is preferable to increase the reaction time.
- the positive electrode active material manufacturing method may include mixing the precursor hydroxide and the Li compound (step S160).
- the Li compound an oxide containing Li may be used, and a compound that can be converted into an oxide by heating (Li carbonate, nitrate, sulfate, oxalate, hydroxide, ammonium salt, sodium salt, etc.) May be used.
- Examples of preferred Li compounds include lithium carbonate and lithium hydroxide.
- Such Li compounds can be used alone or in combination of two or more.
- Mixing of the precursor hydroxide and the Li compound may be performed by either wet mixing or dry mixing. From the viewpoint of simplicity and cost, dry mixing is preferred.
- the mixing ratio of the precursor hydroxide and the Li compound can be determined such that the molar ratio of Li to Ni, Co, and Mn in the target positive electrode active material is realized.
- the precursor hydroxide and the Li compound may be mixed so that the molar ratio of Li to Ni, Co, and Mn is approximately the same as the molar ratio in the positive electrode active material.
- the firing temperature is preferably in the range of about 700 to 1000 ° C. Firing may be performed at the same temperature at a time, or may be performed stepwise at different temperatures.
- the firing time can be appropriately selected. For example, it may be baked at about 800 to 1000 ° C. for about 2 to 24 hours, or baked at about 700 to 800 ° C. for about 1 to 12 hours and then baked at about 800 to 1000 ° C. for about 2 to 24 hours. Also good. In order to obtain a higher output, it is preferable to set the firing temperature in the range of 850 ° C. to 980 ° C. (for example, 850 ° C. to 950 ° C.).
- Such firing conditions can be preferably employed in the production of a positive electrode active material used in a lithium secondary battery for applications where emphasis is placed on enhancing output performance, such as a hybrid vehicle. Further, in order to further widen the SOC range capable of exhibiting a desired output, it is preferable to set the firing temperature in the range of 900 ° C. to 1000 ° C. Such firing conditions can be preferably employed in the production of a positive electrode active material used for a lithium secondary battery for applications in which it is important to increase the amount of electricity that can be taken out, such as an electric vehicle.
- the fired product is crushed and sieved as necessary to adjust the particle size of the positive electrode active material.
- the positive electrode active material in the technology disclosed herein may have an average particle size of the secondary particles of about 1 ⁇ m to 50 ⁇ m.
- a positive electrode active material having an average particle diameter of about 2 ⁇ m to 20 ⁇ m (typically 3 ⁇ m to 10 ⁇ m, for example, about 3 ⁇ m to 7 ⁇ m) is preferable.
- the “average particle diameter” means a median diameter (50% volume average particle diameter; below), which can be derived from a particle size distribution measured based on a particle size distribution measuring apparatus based on a laser scattering / diffraction method, unless otherwise specified. "D50").
- the specific surface area of the positive electrode active material is preferably in the range of approximately 0.5 to 1.8 m 2 / g.
- the average particle diameter of the primary particles constituting the positive electrode active material is at least 5 (for example, 5 to 5) using an electron microscope (both transmission type (TEM) and scanning type (SEM) can be used). It can be grasped by measuring the diameter (longest difference length) with respect to a certain direction of primary particles (about 10) and averaging them.
- TEM transmission type
- SEM scanning type
- a positive electrode active material in which the average particle diameter of the primary particles is 0.1 ⁇ m to 1.0 ⁇ m (for example, 0.2 ⁇ m to 0.7 ⁇ m) is preferable.
- a positive electrode having any of the positive electrode active materials disclosed herein is provided.
- the lithium ion secondary battery provided with the said positive electrode is provided.
- An embodiment of such a lithium ion secondary battery will be described in detail by taking as an example a lithium ion secondary battery having a configuration in which a wound electrode body and a non-aqueous electrolyte are accommodated in a flat rectangular battery case.
- the wound electrode body 20 includes the non-aqueous electrolyte 90 and the electrode body 20. It has the structure accommodated in the flat box-shaped battery case 10 corresponding to a shape.
- the opening 12 of the case 10 is closed with a lid 14.
- the lid body 14 is provided with a positive terminal 38 and a negative terminal 48 for external connection so that a part of the terminals protrudes outward from the lid body 14.
- the lithium ion secondary battery 100 having such a configuration is provided in the lid body 14 after the electrode body 20 is accommodated inside the opening portion 12 of the case 10 and the lid body 14 is attached to the opening portion 12 of the case 10, for example. It can be constructed by injecting an electrolytic solution 90 from a prepared electrolytic solution injection hole (not shown) and then closing the injection hole.
- the electrode body 20 has a positive electrode sheet 30 in which a positive electrode mixture layer 34 containing a positive electrode active material is held by a long sheet-like positive electrode current collector 32 and a negative electrode mixture layer 44 containing a negative electrode active material in a long sheet form.
- the negative electrode sheet 40 held on the negative electrode current collector 42 is overlapped and wound, and the obtained wound body is pressed from the side surface direction and flared to form a flat shape.
- an insulating layer that prevents direct contact between the positive electrode mixture layer 34 and the negative electrode mixture layer 44 is disposed between the positive electrode mixture layer 34 and the negative electrode mixture layer 44.
- two long sheet-like separators 50 are used as the insulating layer.
- the electrode body 20 is configured by winding these separators 50 together with the positive electrode sheet 30 and the negative electrode sheet 40.
- the insulating layer may be coated on one or both surfaces of the positive electrode mixture layer 34 and the negative electrode mixture layer 44.
- the positive electrode sheet 30 is formed such that the positive electrode mixture layer 34 is not provided at one end portion along the longitudinal direction, and the positive electrode current collector 32 is exposed.
- the negative electrode sheet 40 is formed so that the negative electrode mixture layer 44 is not provided at one end along the longitudinal direction, and the negative electrode current collector 42 is exposed.
- a positive electrode terminal 38 is joined to the exposed end portion of the positive electrode current collector 32, and a negative electrode terminal 48 is joined to the exposed end portion of the negative electrode current collector 42.
- the positive and negative electrode terminals 38 and 48 and the positive and negative electrode current collectors 32 and 42 can be joined by, for example, ultrasonic welding, resistance welding, or the like.
- the positive electrode sheet 30 is a paste-like or slurry-like composition in which any of the positive electrode active materials disclosed herein is dispersed in an appropriate solvent together with a conductive material, a binder (binder) and the like used as necessary.
- the positive electrode mixture composition can be preferably prepared by applying the positive electrode current collector composition 32 to the positive electrode current collector 32 and drying the composition.
- the solvent any of an aqueous solvent and an organic solvent can be used. From the viewpoint of highly preventing the situation where W contained in the positive electrode active material is eluted into the solvent, it is preferable to use an organic solvent (for example, N-methyl-2-pyrrolidone (NMP)) as the solvent.
- NMP N-methyl-2-pyrrolidone
- a conductive powder material such as carbon powder or carbon fiber is preferably used.
- carbon powder various carbon blacks such as acetylene black, furnace black, ketjen black, and graphite powder are preferable.
- a conductive material can be used alone or in combination of two or more.
- binder examples include carboxymethyl cellulose (CMC; typically sodium salt), polyvinyl alcohol (PVA), polytetrafluoroethylene (PTFE), styrene butadiene rubber (SBR), polyvinylidene fluoride (PVDF), and the like. It is done.
- CMC carboxymethyl cellulose
- PVA polyvinyl alcohol
- PTFE polytetrafluoroethylene
- SBR styrene butadiene rubber
- PVDF polyvinylidene fluoride
- Such a binder can be used individually by 1 type or in combination of 2 or more types as appropriate.
- Such a binder can also function as a thickener for the positive electrode mixture composition.
- the proportion of the positive electrode active material in the entire positive electrode mixture layer is suitably about 50% by mass or more (typically 50 to 95% by mass), and usually about 70 to 95% by mass. preferable.
- the ratio of the conductive material in the entire positive electrode mixture layer can be, for example, about 2 to 20% by mass, and is usually preferably about 2 to 15% by mass.
- the proportion of the binder in the entire positive electrode mixture layer can be, for example, about 0.5 to 10% by mass, and usually about 1 to 5% by mass is appropriate.
- a conductive member made of a highly conductive metal is preferably used.
- aluminum or an alloy containing aluminum as a main component can be used.
- the shape of the positive electrode current collector 32 may vary depending on the shape of the lithium ion secondary battery, and is not particularly limited, and may be various forms such as a rod shape, a plate shape, a sheet shape, a foil shape, and a mesh shape. .
- an aluminum sheet (aluminum foil) having a thickness of about 10 ⁇ m to 30 ⁇ m can be preferably used as the positive electrode current collector 32.
- the positive electrode mixture composition applied to the positive electrode current collector 32 can be dried under heating as necessary. After drying, the whole may be pressed as necessary.
- the mass of the positive electrode mixture layer 34 provided per unit area of the positive electrode current collector 32 is, for example, 5 to 40 mg / cm. 2 (typically 5 to 20 mg / cm 2 ) is appropriate.
- the density of the positive electrode mixture layer 34 can be, for example, about 1.0 to 3.0 g / cm 3 (typically 1.5 to 3.0 g / cm 3 ).
- the negative electrode sheet 40 provides, for example, a negative electrode current collector 42 with a paste or slurry-like composition (negative electrode mixture composition) in which a negative electrode active material is dispersed in an appropriate solvent together with a binder used as necessary. And it can produce preferably by drying this composition.
- a paste or slurry-like composition negative electrode mixture composition
- a negative electrode active material is dispersed in an appropriate solvent together with a binder used as necessary. And it can produce preferably by drying this composition.
- the negative electrode active material one or more materials conventionally used for lithium ion secondary batteries can be used without any particular limitation.
- a carbon material is mentioned as a suitable negative electrode active material.
- Particulate carbon materials (carbon particles) having a graphite structure (layered structure) at least partially are preferable. Any carbon material of a so-called graphitic material (graphite), a non-graphitizable carbonaceous material (hard carbon), a graphitizable carbonaceous material (soft carbon), or a combination of these materials is preferably used. obtain.
- graphite particles such as natural graphite can be preferably used.
- Carbon particles in which amorphous (amorphous) carbon is added to the surface of graphite may be used.
- the ratio of the negative electrode active material in the entire negative electrode mixture layer is not particularly limited, but it is usually suitable to be about 50% by mass or more, preferably about 90 to 99% by mass (for example, about 95 to 99% by mass). It is.
- the same positive electrode as described above can be used alone or in combination of two or more.
- the addition amount of the binder may be appropriately selected according to the type and amount of the negative electrode active material, and may be, for example, about 1 to 5% by mass of the entire negative electrode mixture layer.
- a conductive member made of a highly conductive metal is preferably used.
- copper or an alloy containing copper as a main component can be used.
- the shape of the negative electrode current collector 42 can be in various forms like the positive electrode current collector 32.
- a copper sheet (copper foil) having a thickness of about 5 ⁇ m to 30 ⁇ m can be preferably used as the negative electrode current collector 42.
- Drying of the positive electrode mixture composition applied to the negative electrode current collector 42 can be performed under heating as necessary. After drying, the whole may be pressed as necessary.
- the mass (total mass of both surfaces) of the negative electrode mixture layer 44 provided per unit area of the negative electrode current collector 42 is, for example, about 3 to 30 mg / cm 2 (typically 3 to 15 mg / cm 2 ). Is appropriate.
- the density of the negative electrode mixture layer 44 can be set to, for example, about 0.8 to 2.0 g / cm 3 (typically 1.0 to 2.0 g / cm 3 ).
- the same separator as a general separator in the field can be used without particular limitation.
- a porous sheet made of a resin such as polyethylene (PE), polypropylene (PP), polyester, cellulose, or polyamide, a nonwoven fabric, or the like can be used.
- Preferable examples include a single layer or multilayer structure porous sheet (microporous resin sheet) mainly composed of one or more kinds of polyolefin resins.
- a PE sheet, a PP sheet, a sheet having a three-layer structure (PP / PE / PP structure) in which PP layers are laminated on both sides of the PE layer, and the like can be suitably used.
- the thickness of the separator is preferably set within a range of about 10 ⁇ m to 40 ⁇ m, for example.
- the separator in the technique disclosed herein may have a configuration in which a porous heat-resistant layer is provided on one side or both sides (typically, one side) of the porous sheet or the nonwoven fabric.
- a porous heat-resistant layer can be, for example, a layer containing an inorganic material (inorganic fillers such as alumina particles can be preferably employed) and a binder.
- nonaqueous electrolytic solution 90 a solution containing an electrolyte (supporting salt) in a nonaqueous solvent (organic solvent) is used.
- a nonaqueous solvent the organic solvent used for the electrolyte solution of a general lithium ion secondary battery can be used, selecting suitably 1 type, or 2 or more types.
- particularly preferred non-aqueous solvents include carbonates such as ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), vinylene carbonate (VC), and propylene carbonate (PC).
- EC ethylene carbonate
- DEC diethyl carbonate
- DMC dimethyl carbonate
- EMC ethyl methyl carbonate
- VC vinylene carbonate
- PC propylene carbonate
- a mixed solvent containing EC, EMC, and DMC at a volume ratio of 3: 3: 4 can be preferably used.
- one or more lithium salts used as an electrolyte in a general lithium ion secondary battery can be appropriately selected and used.
- the lithium salt include LiPF 6 , LiBF 4 , LiClO 4 , LiAsF 6 , Li (CF 3 SO 2 ) 2 N, LiCF 3 SO 3 and the like.
- a particularly preferred example is LiPF 6 .
- the nonaqueous electrolytic solution 90 is preferably prepared, for example, so that the electrolyte concentration is within a range of 0.7 to 1.3 mol / L (typically 1.0 to 1.2 mol / L).
- the nonaqueous electrolytic solution 90 may contain an optional additive as necessary as long as the object of the present invention is not significantly impaired.
- additives include one or more purposes such as, for example, improvement in output performance of the battery 100, improvement in storage stability (suppression of capacity reduction during storage, etc.), improvement in cycle characteristics, improvement in initial charge / discharge efficiency, and the like.
- fluorophosphate preferably difluorophosphate, for example, lithium difluorophosphate represented by LiPO 2 F 2
- LiBOB lithium bisoxalate borate
- the concentration of each additive in the nonaqueous electrolytic solution 90 is usually suitably 0.20 mol / L or less (typically 0.005 to 0.20 mol / L), for example, 0.10 mol / L. Or less (typically 0.01 to 0.10 mol / L).
- a nonaqueous electrolytic solution 90 containing both LiPO 2 F 2 and LiBOB at a concentration of 0.01 to 0.05 mol / L (for example, 0.025 mol / L, respectively) can be given.
- Example 1 ⁇ Preparation of positive electrode active material sample ⁇ (Sample 1) About half the volume of water was placed in a reaction vessel equipped with a stirrer and a nitrogen introduction tube, and heated to 40 ° C. with stirring. After replacing the reaction tank with nitrogen, a 25% (mass basis) aqueous sodium hydroxide solution and 25% while maintaining the space in the reaction tank in a non-oxidizing atmosphere having an oxygen concentration of about 2.0% under a nitrogen stream (Mass basis) Aqueous aqueous solution (NH 3 ⁇ NaOH aqueous solution) having a pH of 12.0 based on a liquid temperature of 25 ° C. and an ammonia concentration of 15 g / L based on a liquid temperature of 25 ° C. by adding appropriate amounts of ammonia water. was prepared.
- Nickel sulfate (NiSO 4 ), cobalt sulfate (CoSO 4 ) and manganese sulfate (MnSO 4 ) have a metal element molar ratio (Ni: Co: Mn) of 0.33: 0.33: 0.33, and these metals
- Ni: Co: Mn metal element molar ratio
- MgSO 4 magnesium sulfate
- Ammonium paratungstate (5 (NH 4 ) 2 O ⁇ 12WO 3 ) was dissolved in water to prepare an aqueous solution Aq C (W aqueous solution) having a tungsten (W) concentration of 0.05 mol / L.
- the aqueous solution Aq A obtained above and the aqueous solution Aq C were mixed with 25% aqueous sodium hydroxide solution and 25% aqueous ammonia, and the pH of the reaction solution was maintained at 12.0.
- the mixture was added and mixed while maintaining the ammonia concentration in the liquid phase at 15 g / L.
- the pH and ammonia concentration were adjusted by adjusting the supply rate of each solution to the reaction tank.
- the precipitated product is separated, washed with water, dried, and a molar ratio of Ni: Co: Mn: W is 0.33: 0.33: 0.33: 0.005, and a precursor containing Mg.
- a hydroxide was obtained.
- the average composition of the hydroxide (hydroxide particles) is Ni 0.33 Co 0.33 Mn 0.33 W 0.005 (OH) 2 + ⁇ (However, Mg is further included. 0 ⁇ ⁇ ⁇ 0 .5)).
- the hydroxide was held in an air atmosphere at a temperature of 150 ° C. for 12 hours.
- lithium carbonate is weighed so that the total molar number of Ni, Co and Mn contained in the hydroxide is M T , and the molar ratio of lithium to M T (Li / M T ) is 1.15.
- the resulting mixture was calcined at 850 ° C. to 950 ° C. for 10 hours in air having an oxygen (O 2 ) concentration of 21 vol%.
- the fired product is pulverized and sieved, and the average composition is Li 1.15 Ni 0.33 Co 0.33 Mn 0.33 W 0.005 O 2 (however, 110 ppm with respect to the total amount of the positive electrode active material)
- a positive electrode active material sample 1 represented by the following formula was further obtained.
- the Mg content was measured by ICP emission spectroscopic analysis.
- a black line in the figure is added on the image for easy viewing of the figure, and indicates a position corresponding to a grain boundary (boundary between primary particles).
- Samples 2 to 10 were confirmed to be in the form of secondary particles in which a plurality of primary particles were collected.
- the positive electrode active material sample 1 was subjected to EDX analysis in the same field of view as in FIG. 4, and the distribution of W was mapped. The result is shown in FIG. In FIG. 5, the portion where a larger amount of W is detected is displayed brighter. As is clear by comparing the brightly displayed portion in FIG. 5 with the position of the grain boundary shown in FIG. 4, W is present in the sample 1 with a bias toward the grain boundary. When the distribution of W was similarly mapped for Samples 2 to 10, it was confirmed that there was a difference in the brightness depending on the W content, but in all cases, W was biased to the grain boundaries. .
- the positive electrode active material sample 1 was subjected to EDX analysis in the same field of view as in FIG. 4 to map the Mg distribution. The result is shown in FIG. A portion where a large amount of Mg is detected is displayed brighter. As is clear by comparing FIG. 6 and FIG. 4, it was confirmed that Mg was present substantially uniformly in sample 1 (the brightness was not biased). When the distribution of Mg was similarly mapped for Samples 2 to 10, it was confirmed that Mg was present evenly, although there was a difference in brightness depending on the Mg content.
- a lithium ion secondary battery (evaluation battery) 100 having the structure shown in FIGS. 2 and 3 was produced.
- these batteries may be referred to as batteries 1 to 10 in association with the positive electrode active material samples 1 to 10 used.
- the positive electrode active material sample, acetylene black (AB) as a conductive material, and PVDF as a binder are mixed with NMP so that the mass ratio thereof is 90: 8: 2,
- a composition was prepared. This composition was applied to both surfaces of an aluminum foil (positive electrode current collector) 32 having a thickness of 15 ⁇ m so that the mass (weight per unit area) after drying was 11.8 mg / cm 2 in total on both surfaces. After drying, the density of the positive electrode mixture layer 34 was adjusted to 2.3 g / cm 3 by pressing with a rolling press. Thus, the positive electrode sheet 30 was produced.
- the negative electrode active material carbon particles having a structure in which amorphous carbon was coated on the surface of graphite particles were used. More specifically, natural graphite powder and pitch are mixed and the pitch is adhered to the surface of the graphite powder (the mass ratio of natural graphite powder: pitch is 96: 4), and 1000 under an inert atmosphere. After calcination for 10 hours at 1 ° C. to 1300 ° C., the mixture was sieved to obtain a negative electrode active material having an average particle diameter (D50) of 8 to 11 ⁇ m and a specific surface area of 3.5 to 5.5 m 2 / g.
- D50 average particle diameter
- This negative electrode active material, CMC, and SBR were mixed with ion-exchanged water so that the mass ratio thereof was 98.6: 0.7: 0.7 to prepare a slurry composition.
- This composition was applied to both surfaces of a copper foil (negative electrode current collector) 42 having a thickness of 10 ⁇ m so that the total mass (weight per unit area) after drying was 7.5 mg / cm 2 .
- the density of the negative electrode mixture layer 44 was adjusted to 1.0 to 1.4 g / cm 3 by pressing with a rolling press.
- the negative electrode sheet 40 was produced.
- the positive electrode sheet 30 and the negative electrode sheet 40 were wound together with two porous polyethylene sheets 50 (thickness: 20 ⁇ m), and formed into a flat shape to produce the electrode body 20.
- the positive electrode terminal 38 and the negative electrode terminal 48 were attached to the lid body 14, and these terminals 38 and 48 were welded to the positive electrode current collector 32 and the negative electrode current collector 42 exposed at the end of the electrode body 20, respectively.
- the electrode body 20 thus connected to the lid body 14 was accommodated in the opening 10 of the case 10 and the lid body 14 was laser welded to the opening 12 of the case 10.
- a nonaqueous electrolytic solution 90 was injected from an electrolytic solution injection hole (not shown) provided in the lid 14.
- the facing capacity ratio calculated from the charge capacity of the positive electrode and the charge capacity of the negative electrode is adjusted to 1.5 to 1.9.
- the capacity of the battery 100 is approximately 4 Ah.
- the rated capacity of the evaluation test battery was measured according to the following procedures 1 to 3 in the voltage range from 3.0 V to 4.1 V at a temperature of 25 ° C. for the evaluation test battery after the conditioning process.
- [Procedure 1] After reaching 3.0 V by 1 C constant current discharge, discharge at a constant voltage for 2 hours, and then rest for 10 seconds.
- [Procedure 2] After reaching 4.1 V by constant current charging at 1 C, charging is performed for 2.5 hours by constant voltage charging, and then paused for 10 seconds.
- [Procedure 3] After reaching 3.0 V by constant current discharge of 0.5 C, discharge at constant voltage discharge for 2 hours, and then stop for 10 seconds.
- the discharge capacity (CCCV discharge capacity) in the discharge from the constant current discharge to the constant voltage discharge in the procedure 3 is defined as the rated capacity.
- steps 1 to 3 were repeated while increasing the constant watt discharge power from 350 W to 600 W in step 4 in step 4, but the measurement conditions for low SOC and 0 ° C. output are not limited to this.
- the discharge power may be increased from 350 W by a constant wattage different from the above (for example, 5 W or 15 W), or the constant watt discharge power may be increased from 600 W by a constant wattage (for example, 5 W, It may be lowered by 10W or 15W).
- the low SOC / 0 ° C. output indicates the output that the evaluation battery can exert when left in a low SOC and low temperature environment of 0 ° C. for a predetermined time. It is shown that the higher the output value (wattage), the higher the output of the evaluation battery even under such usage conditions.
- steps 1 to 3 were repeated while increasing the constant watt discharge output from 80 W to 200 W in step 4 in step 4, but the measurement conditions for low SOC and ⁇ 30 ° C. output are not limited to this.
- the watt discharge output may be increased from 80 W by a constant wattage different from the above (for example, 5 W or 15 W), or from 200 W by a certain wattage (for example, 5 W, 10 W, or It may be lowered by 15W).
- the low SOC ⁇ ⁇ 30 ° C. output indicates an output that the evaluation battery can exert even when left in a very low temperature environment of ⁇ 30 ° C. for a predetermined time. It shows that the higher the output value (wattage), the higher the output of the evaluation battery can be under such severe use conditions.
- steps 1 to 3 were repeated while increasing the constant watt discharge output from 100 W to 250 W in step 4 in step 4.
- the watt discharge output may be increased from 100 W by a certain wattage different from the above (for example, 5 W, 10 W, or 15 W), or from 250 W by a certain wattage (for example, 5 W, 10 W It may be lowered by 15W, 15W or 20W.
- the above-mentioned medium SOC / -30 ° C output is a moderate SOC (SOC region where the battery is frequently used), and the battery for evaluation exhibits even when left in a very low temperature environment of -30 ° C for a predetermined time. Shows the output you get. It shows that the higher the output value (wattage), the higher the output power of the evaluation battery can be under such use conditions.
- the low temperature output at a low SOC is 0 ° C. as compared with the battery 10 using the positive electrode active material sample whose Mg content is 50 ppm or less. It was clearly improved both at -30 ° C.
- the Mg content in the positive electrode active material was more than 50 ppm and 1000 ppm or less (more specifically, 100 ppm or more and 800 ppm or less), a particularly remarkable low SOC output improvement effect was obtained. Further, when the Mg content exceeded 1000 ppm (Example 9), the low temperature ( ⁇ 30 ° C.) output in the medium SOC decreased. Therefore, in the lithium ion secondary battery having the above configuration, the Mg content is preferably in the range of more than 50 ppm and not more than 1000 ppm from the viewpoint of achieving both high output at low SOC and high output at medium SOC. .
- the W content is the output of medium SOC over the entire range of 0.05 mol% to 2 mol% with the total amount of Ni, Co and Mn being 100 mol%. It was confirmed that the effect of improving the low SOC output can be obtained without significant loss.
- the following experiment was performed in order to confirm that W present in a biased manner on the surface of the primary particles contributes to charge / discharge. That is, a plurality of batteries according to Example 1 were prepared, and the conditioning process and the rated capacity measurement were performed, respectively. And after the rated capacity measurement (SOC 0%), after the rated capacity measurement, charge to SOC 60% at a constant current of 1 C at 25 ° C., and after the rated capacity measurement, charge to SOC 100% at a constant current of 1 C at 25 ° C. The battery adjusted to three kinds of charge states was disassembled and the positive electrode active material was taken out.
- X-ray absorption fine structure (XAFS) spectra of W were measured for each of these 0%, 60%, and 100% positive electrode active materials. The obtained results are shown in FIG. This figure shows how the peak intensity of W increases as the SOC increases. This increase in peak intensity is understood to mean an increase in electron vacancies, that is, an increase in valence. This result shows that W that is biased on the surface of the primary particles contributes to charging / discharging by increasing the valence due to the increase in SOC, thereby improving the charging / discharging efficiency (and thus improving the output in the low SOC region). Indicates that it can be useful.
- Non-aqueous electrolyte 100 Lithium ion secondary battery (lithium secondary battery)
Abstract
Description
ここに開示される技術における正極活物質は、リチウム遷移金属酸化物の一次粒子が集まった二次粒子の形態をなす。上記リチウム遷移金属酸化物は、Ni、CoおよびMnのうち少なくとも一種を含むリチウム酸化物である。その結晶構造は、層状、スピネル型等であり得る。好ましい一態様では、上記リチウム遷移金属酸化物が層状(典型的には岩塩型)の結晶構造を有する。ここに開示される技術は、かかる正極活物質を備えたリチウム二次電池用正極、および、該正極を構成要素とする種々のリチウム二次電池(典型的にはリチウムイオン二次電池)に適用され得る。
上記正極活物質は、Ni、CoおよびMnのうち少なくとも一種を含有するほか、さらにWおよびMgを含有する。ここに開示される技術の一つの特徴は、上記Mgが一次粒子の内部全体に存在する一方、上記Wが一次粒子の表面に偏って存在する点にある。WおよびMgがこのように分布していることにより、低SOC領域における出力(特に低温出力)を効果的に向上させたリチウム二次電池を実現することができる。
Li1+mNipCoqMnrM1 sO2 (I)
上記式(I)において、mは、0≦m≦0.2(例えば0.05≦x≦0.2)であり得る。上記式中のpは、0.1<p≦1(例えば0.3<p<0.9、好ましくは0.3<p<0.6)であり得る。qは、0≦q≦0.5(例えば0.1<q<0.4、好ましくは0.3<q<0.6)であり得る。rは、0≦r≦0.5(例えば0.1<r<0.4、好ましくは0.3<r<0.6)であり得る。ただし、p+q+r≦1(典型的には0.8≦p+q+r≦1、例えば0.9≦p+q+r≦1)である。M1は、Al、Cr、Fe、V、Ti、Mo、Cu、Zn、Ga、In、Sn、La、Ce、CaおよびNaから選択される一種または二種以上であり得る。sは、0≦s≦0.05であり得る。sが実質的に0(すなわち、M1を実質的に含有しない酸化物)であってもよい。
このような正極活物質を製造する方法としては、該活物質を最終生成物として調製可能な方法を適宜採用することができる。以下、主に上記リチウム遷移金属酸化物がNi、CoおよびMnの全てを含む層状構造の酸化物(LiNiCoMn酸化物)である正極活物質を例として、該正極活物質の好ましい製造方法の一実施態様をより詳しく説明するが、ここに開示される技術の適用対象をかかる正極活物質に限定する意図ではない。
上記水溶液AqAは、例えば、適当なNi化合物、Co化合物、Mn化合物、およびMg化合物のそれぞれ所定量を水性溶媒に溶解させて調製することができる。これらの金属化合物としては、各金属の塩(すなわち、Ni塩、Co塩、Mn塩、およびMg塩)を好ましく使用することができる。これらの金属塩を水性溶媒に添加する順序は特に制限されない。また、各塩の水溶液を混合して調製してもよい。あるいは、Ni塩、Co塩、Mn塩を含む水溶液に、Mg塩の水溶液を混合してもよい。これらの金属塩(Ni塩、Co塩、Mn塩、Mg塩)におけるアニオンは、それぞれ、該塩が所望の水溶性となるように選択すればよい。例えば、硫酸イオン、硝酸イオン、塩化物イオン、炭酸イオン、水酸化物イオン等であり得る。すなわち、上記金属塩は、それぞれ、Ni、Co、Mn、Mgの硫酸塩、硝酸塩、塩酸塩、炭酸塩、水酸化物等であり得る。これら金属塩のアニオンは、全てまたは一部が同じであってもよく、互いに異なってもよい。これらの塩は、それぞれ、水和物等の溶媒和物であってもよい。図1には、各金属の硫酸塩を用いる例を示している。水溶液AqAの濃度は、全遷移金属(Ni、Co、Mn)の合計が1.0~2.2mol/L程度となる濃度であることが好ましい。
本態様に係る正極活物質製造方法は、また、Wを含む水溶液AqC(以下、「W水溶液」ということもある。)を準備することを含む(ステップS120)。このW水溶液は、典型的には、Ni、Co、MnおよびMgを実質的に含有しない(これらの金属元素を少なくとも意図的には含有させないことをいい、不可避的不純物等として混入することは許容され得る。)組成物である。例えば、金属元素として実質的にWのみを含むW水溶液を好ましく使用し得る。上記W水溶液は、上述した水溶液AqAと同様に、所定量のW化合物を水性溶媒に溶解させて調製することができる。かかるW化合物としては、例えば、各種のW塩を用いることができる。好ましい一態様では、タングステン酸(Wを中心元素とするオキソ酸)の塩を用いる。上記W塩におけるカチオンは、該塩が水溶性となるように選択することができ、例えばアンモニウムイオン、ナトリウムイオン、カリウムイオン等であり得る。好ましく使用し得るW塩の一例として、パラタングステン酸アンモニウム(5(NH4)2O・12WO3)が挙げられる(図1)。上記W塩は、水和物等の溶媒和物であってもよい。W水溶液の濃度は、W元素基準で0.01~1mol/L程度であることが好ましい。
本態様に係る方法は、さらに、アルカリ性水溶液を準備することを含み得る(ステップS130)。このアルカリ性水溶液は、水性溶媒にアルカリ剤(液性をアルカリ側に傾ける作用のある化合物)が溶解した水溶液である。上記アルカリ剤としては、強塩基(例えば、水酸化ナトリウム、水酸化カリウム等のアルカリ金属水酸化物)および弱塩基(アンモニア、アミン等)のいずれも使用可能である。少なくともアンモニアを含むアルカリ性水溶液AqBが好ましい。ここに開示される技術の好ましい一態様では、弱塩基および強塩基の両方を含むアルカリ性水溶液を使用する。例えば、アンモニアと水酸化ナトリウムとを含むアルカリ性水溶液を好ましく使用し得る。組成の異なる複数のアルカリ性水溶液(例えば、アンモニア水と水酸化ナトリウム水溶液)を使用してもよい。典型的には、Ni、Co、Mn、MgおよびWを実質的に含有しない(これらの金属元素を少なくとも意図的には含有させないことをいい、不可避的不純物等として混入することは許容され得る。)組成物である。
そして、水溶液AqAとW水溶液とを、アルカリ性の(好ましくはpH11~14の)条件下で混合することにより、Ni、Co、Mn、MgおよびWを含む前駆体水酸化物を析出(晶析)させる(ステップS140)。したがって、上記水溶液AqAは、中和された後にWと混合される。例えば、初期pHが11~14(典型的には11.5~12.5、例えば12.0程度)のアルカリ性水溶液を反応槽内に用意し(ステップS142)、この初期pHを維持しつつ、該反応槽に水溶液AqAおよびW水溶液AqCを適切な速度で供給して撹拌混合する。このとき、上記初期pHを維持するために、必要に応じて上記反応槽にアルカリ性水溶液を追加供給するとよい(ステップS144)。析出した前駆体水酸化物は、晶析終了後、水洗・濾過して乾燥させ、所望の粒径を有する粒子状に調製するとよい(ステップS150)。
ここに開示される技術の一実施形態に係るリチウムイオン二次電池は、例えば図2および図3に示されるように、捲回電極体20が、非水電解液90とともに、該電極体20の形状に対応した扁平な箱状の電池ケース10に収容された構成を有する。ケース10の開口部12は蓋体14により塞がれている。蓋体14には、外部接続用の正極端子38および負極端子48が、それら端子の一部が蓋体14から電池の外方に突出するように設けられている。かかる構成のリチウムイオン二次電池100は、例えば、ケース10の開口部12から電極体20を内部に収容し、該ケース10の開口部12に蓋体14を取り付けた後、蓋体14に設けられた電解液注入孔(図示せず)から電解液90を注入し、次いで上記注入孔を塞ぐことによって構築することができる。
(サンプル1)
攪拌装置および窒素導入管を備えた反応槽に、その容量の半分程度の水を入れ、攪拌しながら40℃に加熱した。該反応槽を窒素置換した後、窒素気流下、反応槽内の空間を酸素濃度2.0%程度の非酸化性雰囲気に維持しつつ、25%(質量基準)水酸化ナトリウム水溶液と、25%(質量基準)アンモニア水とを、それぞれ適量加えて、液温25℃を基準とするpHが12.0であり、液相のアンモニア濃度が15g/Lであるアルカリ性水溶液(NH3・NaOH水溶液)を調製した。
水溶液AqAにおけるMg濃度およびW水溶液におけるW濃度を、Mg含有量およびW含有量がそれぞれ表1に示す値となるように調節した。その他の点については正極活物質サンプル1の作製と同様にして、正極活物質サンプル2~10を作製した。
これら正極活物質サンプル1~10は、いずれも、平均粒径(D50)が3μm~8μmの範囲にあり、比表面積が0.5~1.9m2/gの範囲となるように調整した。
上記で得られた正極活物質サンプル1をTEMで観察したところ、複数の一次粒子が集まった二次粒子の形態であることが確認された。TEM像から求めた一次粒子の平均粒径は約0.5μmであった。上記一次粒子の平均粒径は、約10個の一次粒子について、一定方向に対する直径(最長の差渡し長さ)を測定し、それらを算術平均して求めた。サンプル1のTEM像の一つを図4に示す。このTEM像は、日本電子株式会社製の透過型電子顕微鏡、型式「JEM-2100F」を用いて、加速電圧200kVの条件で得られたものである。図中の黒線は、図を見やすくするために画像上で加えたものであって、粒界(一次粒子同士の境界)にあたる位置を示している。サンプル2~10についても、同様に、複数の一次粒子が集まった二次粒子の形態であることが確認された。
正極活物質サンプル1について、図4と同一の視野にてEDX分析を行い、Wの分布をマッピングした。その結果を図5に示す。この図5では、Wが多く検出された箇所ほど明るく表示されている。図5において明るく表示された箇所と、図4に示される粒界の位置とを見比べることにより明らかなように、このサンプル1ではWが粒界に偏って存在ししている。サンプル2~10についても同様にWの分布をマッピングしたところ、Wの含有量によって明るさの程度に差はあるものの、いずれも、Wが粒界に偏って存在していることが確認された。
上記正極活物質サンプル1~10をそれぞれ使用して、概略図2、図3に示す構造のリチウムイオン二次電池(評価用電池)100を作製した。以下、これらの電池を、使用した正極活物質サンプル1~10に対応づけて、電池1~10ということがある。
コンディショニング工程は、次の手順1~2によって行った。
[手順1]1Cの定電流(1Cは、満充電状態の電池を1時間で放電終止電圧まで放電させる電流値を意味する。放電時間率と称されることもある。)にて端子間電圧が4.1Vに到達するまで充電(CC充電)した後、5分間休止する。
[手順2]手順1の後、定電圧で1.5時間充電(CV充電)し、5分間休止する。
評価試験用電池の定格容量は、上記コンディショニング工程後の評価試験用電池について、温度25℃において、3.0Vから4.1Vの電圧範囲で、次の手順1~3に従って測定した。
[手順1]1Cの定電流放電によって3.0Vに到達後、定電圧にて2時間放電し、その後、10秒間休止する。
[手順2]1Cの定電流充電によって4.1Vに到達後、定電圧充電にて2.5時間充電し、その後、10秒間休止する。
[手順3]0.5Cの定電流放電によって3.0Vに到達後、定電圧放電にて2時間放電し、その後、10秒間停止する。
上記手順3における、定電流放電から定電圧放電に至る放電における放電容量(CCCV放電容量)を、定格容量とする。
以下の手順1~5により、低SOCに調整された評価用電池の0℃における出力を測定した。
[手順1;SOC調整]上記コンディショニング工程および定格容量測定後の電池を、常温(ここでは25℃)の温度環境にて、1Cの定電流で3VからSOC27%まで充電(CC充電)し、次いで定電圧で2.5時間充電(CV充電)した。
[手順2;0℃に保持]手順1後の電池を、0℃の恒温槽内に6時間保持した。
[手順3;定ワット放電]手順2後の電池を、0℃の温度環境において定ワット(W)にて放電し、放電開始から電圧が2.0V(放電カット電圧)になるまでの秒数を測定する。
[手順4;繰り返し]:手順3の定ワット放電における放電出力(定ワット放電の放電電力量)を350W~600Wの間で異ならせて、上記手順1~3を繰り返す。より具体的には、手順3の定ワット放電における放電出力を、1回目350W、2回目360W、3回目370W・・・と10Wづつ上げながら、該ワット数が600Wになるまで上記手順1~3を繰り返す。
[手順5;出力値の算出]:手順4において各定ワット放電において測定された電圧2.0Vまでの秒数を横軸にとり、そのときの定ワット放電出力を縦軸にとったプロットの近似曲線から、電圧2.0Vまでの秒数が2秒となるときの出力値(低SOC・0℃出力)を求める。
以下の手順1~5により、低SOCに調整された評価用電池の-30℃における出力を測定した。
[手順1;SOC調整]上記コンディショニング工程および定格容量測定後の電池を、常温(ここでは25℃)の温度環境にて、1Cの定電流で3VからSOC27%まで充電(CC充電)し、次いで定電圧で2.5時間充電(CV充電)した。
[手順2;-30℃に保持]手順1後の電池を、-30℃の恒温槽内に6時間保持した。
[手順3;定ワット放電]手順2後の電池を、-30℃の温度環境において定ワット(W)にて放電し、放電開始から電圧が2.0V(放電カット電圧)になるまでの秒数を測定する。
[手順4;繰り返し]:手順3の定ワット放電における放電出力(定ワット放電の放電電力量)を80W~200Wの間で異ならせて、上記手順1~3を繰り返す。より具体的には、手順3の定ワット放電における放電出力を、1回目80W、2回目90W、3回目100W・・・と10Wづつ上げながら、該ワット数が200Wになるまで上記手順1~3を繰り返す。
[手順5;出力値の算出]:手順4において各定ワット放電において測定された電圧2.0Vまでの秒数を横軸にとり、そのときの定ワット放電出力を縦軸にとったプロットの近似曲線から、電圧2.0Vまでの秒数が2秒となるときの出力値(低SOC・-30℃出力)を求める。
以下の手順1~5により、中SOCに調整された評価用電池の0℃における出力を測定した。
[手順1;SOC調整]上記コンディショニング工程および定格容量測定後の電池を、常温(ここでは25℃)の温度環境にて、1Cの定電流で3VからSOC56%まで充電(CC充電)し、次いで定電圧で2.5時間充電(CV充電)した。
[手順2;-30℃に保持]手順1後の電池を、-30℃の恒温槽内に6時間保持した。
[手順3;定ワット放電]手順2後の電池を、-30℃の温度環境において定ワット(W)にて放電し、放電開始から電圧が2.0V(放電カット電圧)になるまでの秒数を測定する。
[手順4;繰り返し]:手順3の定ワット放電における放電出力(定ワット放電の放電電力量)を100W~250Wの間で異ならせて、上記手順1~3を繰り返す。より具体的には、手順3の定ワット放電における放電出力を、1回目100W、2回目120W、3回目140W・・・と20Wづつ上げながら、該ワット数が250Wになるまで上記手順1~3を繰り返す。
[手順5;出力値の算出]:手順4において各定ワット放電において測定された電圧2.0Vまでの秒数を横軸にとり、そのときの定ワット放電出力を縦軸にとったプロットの近似曲線から、電圧2.0Vまでの秒数が2秒となるときの出力値(中SOC・-30℃出力)を求める。
10 電池ケース
12 開口部
14 蓋体
20 捲回電極体
30 正極シート(正極)
32 正極集電体
34 正極合剤層
38 正極端子
40 負極シート(負極)
42 負極集電体
44 負極合剤層
48 負極端子
50 セパレータ
90 非水電解液
100 リチウムイオン二次電池(リチウム二次電池)
Claims (9)
- 正極と負極と非水電解質とを備えたリチウム二次電池であって、
前記正極は、リチウム遷移金属酸化物の一次粒子が集まった二次粒子の形態をなす正極活物質を有し、
前記正極活物質は、Ni、CoおよびMnのうち少なくとも一種を含み、さらにWおよびMgを含み、
前記Wは前記一次粒子の表面に偏って存在し、
前記Mgは前記一次粒子の内部全体に存在し、
前記正極活物質におけるMgの含有量は、質量基準で、該活物質の総量に対して50ppmを超える量である、リチウム二次電池。 - 前記正極活物質におけるMgの含有量は、質量基準で、該活物質の総量に対して1000ppm以下である、請求項1に記載のリチウム二次電池。
- 前記正極活物質におけるWの含有量は、Ni、CoおよびMnの総量を100モル%として0.05モル%以上2モル%以下である、請求項1または2に記載のリチウム二次電池。
- 前記リチウム遷移金属酸化物は、Ni、CoおよびMnの全てを含む層状構造の酸化物である、請求項1から3のいずれか一項に記載のリチウム二次電池。
- 車両の駆動電源として用いられる、請求項1から4のいずれか一項に記載のリチウム二次電池。
- リチウム二次電池用の正極活物質であって、リチウム遷移金属酸化物の一次粒子が集まった二次粒子の形態をなし、Ni、CoおよびMnのうち少なくとも一種を含み、さらにWおよびMgを含む正極活物質を製造する方法であって:
前記Ni、CoおよびMnの少なくとも一種およびMgを含む水溶液AqAを準備すること;
Wを含む水溶液AqCを準備すること;
前記水溶液AqAと前記水溶液AqCとをアルカリ性条件下で混合して、前記Ni、CoおよびMnの少なくとも一種とMgとWとを含む水酸化物を析出させること;
前記水酸化物とリチウム化合物とを混合すること;および、
前記混合物を焼成して前記リチウム遷移金属酸化物を生成させること;
を包含する、正極活物質製造方法。 - 前記水酸化物の析出は、pHを11~14に維持しつつ行われる、請求項6に記載の方法。
- 前記水酸化物の析出は、少なくともアンモニアを含むアルカリ性水溶液を用いて前記アルカリ性条件を維持しつつ行われる、請求項6または7に記載の方法。
- 請求項6から8のいずれか一項に記載の方法により製造された正極活物質を備える、リチウム二次電池。
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US14/122,213 US9126845B2 (en) | 2011-05-31 | 2011-05-31 | Lithium secondary battery |
CN201180071231.6A CN103563139B (zh) | 2011-05-31 | 2011-05-31 | 锂二次电池 |
KR1020137034095A KR101584880B1 (ko) | 2011-05-31 | 2011-05-31 | 리튬 이차 전지 |
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JP2014183031A (ja) * | 2013-03-21 | 2014-09-29 | Toyota Motor Corp | リチウムイオン二次電池およびその製造方法 |
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KR101848979B1 (ko) * | 2014-10-31 | 2018-05-24 | 주식회사 엘지화학 | 전이금속 산화물 전구체, 리튬 복합 전이금속 산화물, 이를 포함하는 양극 및 이차전지 |
JP6428192B2 (ja) * | 2014-11-20 | 2018-11-28 | 戸田工業株式会社 | 非水電解質二次電池用正極活物質粒子粉末とその製造方法、および非水電解質二次電池 |
JP6417888B2 (ja) | 2014-11-20 | 2018-11-07 | 戸田工業株式会社 | 非水電解質二次電池用正極活物質粒子粉末とその製造方法、および非水電解質二次電池 |
WO2018012466A1 (ja) * | 2016-07-13 | 2018-01-18 | 株式会社Gsユアサ | リチウム二次電池用正極活物質、その製造方法及びリチウム二次電池 |
US20180145317A1 (en) * | 2016-11-18 | 2018-05-24 | Semiconductor Energy Laboratory Co., Ltd. | Positive electrode active material, method for manufacturing positive electrode active material, and secondary battery |
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CN114122500A (zh) * | 2021-11-24 | 2022-03-01 | 东莞新能安科技有限公司 | 电化学装置及其控制方法、电子装置、介质和充电装置 |
KR20230141104A (ko) * | 2022-03-31 | 2023-10-10 | 에스케이온 주식회사 | 리튬 이차 전지용 양극 활물질 및 이를 포함하는 리튬 이차 전지 |
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JPWO2012164693A1 (ja) | 2014-07-31 |
US20140127582A1 (en) | 2014-05-08 |
JP5692617B2 (ja) | 2015-04-01 |
KR20140008464A (ko) | 2014-01-21 |
KR101584880B1 (ko) | 2016-01-13 |
CN103563139B (zh) | 2016-07-06 |
CN103563139A (zh) | 2014-02-05 |
US9126845B2 (en) | 2015-09-08 |
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