Classifications

• • 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
  • H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
  • C01G51/00—Compounds of cobalt
  • C01G51/40—Complex oxides containing cobalt and at least one other metal element
  • C01G51/42—Complex oxides containing cobalt and at least one other metal element containing alkali metals, e.g. LiCoO2
  • C01G51/44—Complex oxides containing cobalt and at least one other metal element containing alkali metals, e.g. LiCoO2 containing manganese
  • C01G51/50—Complex oxides containing cobalt and at least one other metal element containing alkali metals, e.g. LiCoO2 containing manganese of the type (MnO2)n-, e.g. Li(CoxMn1-x)O2 or Li(MyCoxMn1-x-y)O2
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
  • C01G53/00—Compounds of nickel
  • C01G53/40—Complex oxides containing nickel and at least one other metal element
  • C01G53/42—Complex oxides containing nickel and at least one other metal element containing alkali metals, e.g. LiNiO2
  • C01G53/44—Complex oxides containing nickel and at least one other metal element containing alkali metals, e.g. LiNiO2 containing manganese
  • C01G53/50—Complex oxides containing nickel and at least one other metal element containing alkali metals, e.g. LiNiO2 containing manganese of the type (MnO2)n-, e.g. Li(NixMn1-x)O2 or Li(MyNixMn1-x-y)O2
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/052—Li-accumulators
  • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/36—Selection of substances as active materials, active masses, active liquids
  • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
  • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
  • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/36—Selection of substances as active materials, active masses, active liquids
  • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
  • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
  • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/80—Particles consisting of a mixture of two or more inorganic phases
• • 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
  • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
  • H01M2004/028—Positive electrodes
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/10—Energy storage using batteries

Definitions

• the present invention relates to a method for producing a positive electrode active material for a lithium ion secondary battery, a method for producing a positive electrode for a lithium ion secondary battery using the same, and a method for producing a lithium ion secondary battery.
• Lithium ion secondary batteries are widely used in portable electronic devices such as mobile phones and notebook computers.
• a positive electrode active material for a lithium ion secondary battery includes a composite oxide of lithium and a transition metal or the like such as LiCoO 2 , LiNiO 2 , LiNi 0.8 Co 0.2 O 2 , LiMn 2 O 4 (hereinafter referred to as lithium Containing complex oxide).
• LiCoO 2 , LiNiO 2 , LiNi 0.8 Co 0.2 O 2 , LiMn 2 O 4 hereinafter referred to as lithium Containing complex oxide.
• miniaturization and weight reduction have been demanded as portable electronic devices and in-vehicle lithium ion secondary batteries, and further improvement in charge and discharge efficiency is desired.
• Patent Document 1 discloses an aqueous solution containing a specific cation M, an aqueous solution containing an anion N that reacts with the cation M to form a hardly soluble salt, and a lithium-containing composite containing an Li element and a transition metal element.
• a method for improving the retention rate (cycle retention rate) of the discharge capacity after repeating the discharge cycle is described by heating after contacting the oxide and providing a coating layer on the lithium-containing composite oxide. Yes.
• Patent Document 2 discloses that when a lithium-containing composite oxide powder containing a Li element and a transition metal element is treated with nitric acid, treated with ammonia gas, and then heat-treated, the initial charge / discharge efficiency (initial efficiency) is improved. It is described.
• the charge / discharge efficiency in the lithium ion secondary battery is not necessarily sufficient, and improvement is desired.
• a lithium ion secondary battery with high initial efficiency and a high cycle maintenance rate is desirable.
• the present invention has been made in view of the above circumstances, and a method for producing a positive electrode active material for a lithium ion secondary battery capable of simultaneously improving the initial efficiency and the cycle maintenance ratio in the lithium ion secondary battery, and the use thereof. It is an object of the present invention to provide a method for producing a positive electrode for a lithium ion secondary battery and a method for producing a lithium ion secondary battery.
• the gist of the present invention is the following [1] to [15].
• [1] A method for producing a positive electrode active material for a lithium ion secondary battery having the following steps (I), (II) and (III) in this order.
• Step (I) A step of bringing a lithium-containing composite oxide (I) containing a Li element and a transition metal element into contact with a cleaning liquid, and separating the cleaning liquid after the contact to obtain a lithium-containing composite oxide (II).
• Step (II) A step of obtaining lithium-containing composite oxide (III) by bringing lithium-containing composite oxide (II) into contact with the following composition (1) and composition (2).
• Step (III) A step of heating the lithium-containing composite oxide (III).
• Composition (1) An aqueous solution containing a monoatomic or polyatomic anion (A) containing at least one element (a) selected from the group consisting of S, P, F, and B.
• Composition (2) Li, Mg, Ca, Sr, Ba, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, Al, Cation of a single atom or a complex of at least one metal element (m) selected from the group consisting of Ga, In, Sn, Sb, Bi, La, Ce, Pr, Nd, Gd, Dy, Er, and Yb ( An aqueous solution containing M).
• step (II) The anion contained in the composition (1) (A) it is, F - a is, [1] to manufacture a cathode active material for a lithium ion secondary battery according to any one of [3] Method.
• step (II) the molar ratio of each anion (A) contained in the composition (1) to the total amount of transition metal elements contained in the lithium-containing composite oxide (I) Lithium according to any one of [1] to [4], which is contacted so that a sum of values obtained by multiplying absolute values of valences of ions (A) is within a range of 0.001 to 0.15.
• the lithium-containing composite oxide (I) contains Li element and at least one transition metal element selected from the group consisting of Ni, Co, and Mn, and the molar amount of Li element is the transition metal element
• Me is at least one element selected from the group consisting of Co and Ni
• Me ′ is at least one element selected from the group consisting of Al, Cr, Mg, Mo, Ru, Ti, Zr, and Fe.
• 0.1 ⁇ x 1 ⁇ 0.25, 0.5 ⁇ y 1 / (y 1 + z 1 ) ⁇ 0.8, 0 ⁇ ⁇ ⁇ 0.1, x 1 + y 1 + z 1 1, 1 .9 ⁇ p ⁇ 2.1, 0 ⁇ q ⁇ 0.1.
• the lithium-containing composite oxide (II) is brought into contact with the composition (1) and the composition (2) to the lithium-containing composite oxide (II) under stirring.
• the composition (2) the method for producing a positive electrode active material for a lithium ion secondary battery according to [12].
• a lithium ion secondary battery is produced using the process for producing a positive electrode for a lithium ion secondary battery by the production method according to [14], and the positive electrode for a lithium ion secondary battery, a negative electrode, a nonaqueous electrolyte, and a separator.
• the manufacturing method of a lithium ion secondary battery which has the process to comprise.
• the positive electrode active material for lithium ion secondary batteries which can improve the initial stage efficiency and cycle maintenance factor in a lithium ion secondary battery simultaneously, and the positive electrode for lithium ion secondary batteries are obtained.
• a lithium ion secondary battery excellent in initial efficiency and cycle maintenance rate can be obtained.
• an element symbol indicates an element, and does not indicate a single substance (for example, metal) of the element unless otherwise specified.
• ⁇ Method for producing positive electrode active material for lithium ion secondary battery> In the method for producing a positive electrode active material for a lithium ion secondary battery of the present invention (hereinafter referred to as this production method), the following steps (I), (II) and (III) are carried out in this order. Thereby, compared with the case where only each process is performed, the synergistic effect by this combination is acquired, and an initial stage efficiency and a cycle maintenance factor can be improved more.
• This manufacturing method may include other steps between the respective steps as long as the following steps are performed in this order. From the viewpoint of production efficiency, it is more preferable to perform the following steps continuously.
• composition (1) and the composition (2) are the following aqueous solutions, respectively.
• a coating solution An aqueous solution containing a monoatomic or polyatomic anion (A) containing at least one element (a) selected from the group consisting of S, P, F, and B.
• Composition (2) Li, Mg, Ca, Sr, Ba, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, Al, Cation of a single atom or a complex of at least one metal element (m) selected from the group consisting of Ga, In, Sn, Sb, Bi, La, Ce, Pr, Nd, Gd, Dy, Er, and Yb ( An aqueous solution containing M).
• the lithium-containing composite oxide (I) used in this production method contains Li and a transition metal element.
• the lithium-containing composite oxide before being brought into contact with the cleaning liquid is referred to as lithium-containing composite oxide (I).
• the transition metal element includes at least one selected from the group consisting of Ni, Co, Mn, Fe, Cr, V, and Cu.
• a known lithium-containing composite oxide can be used as an active material for a lithium ion secondary battery.
• a lithium containing complex oxide may be used individually by 1 type, and may use 2 or more types together.
• the lithium-containing composite oxide (I) for example, the following compound (i), (ii), (iii), or (iv) is preferable.
• Compound (i) Li and at least one transition metal element selected from the group consisting of Ni, Co, and Mn, and the molar amount of Li is 1.2 with respect to the total molar amount of the transition metal element. A compound that is more than doubled.
• Compound (i) is preferably a compound represented by the following formula (1).
• Compound (ii) Compound represented by the following formula (2).
• Compound (iv) A compound represented by the following formula (4).
• the compound (i) is more preferable in that a high capacity in a lithium ion secondary battery can be obtained.
• Me is at least one element selected from the group consisting of Co and Ni
• Me ′ is selected from the group consisting of Al, Cr, Mg, Mo, Ru, Ti, Zr, and Fe. At least one kind.
• 0.1 ⁇ x 1 ⁇ 0.25, 0.5 ⁇ y 1 / (y 1 + z 1 ) ⁇ 0.8, 0 ⁇ ⁇ ⁇ 0.1, x 1 + y 1 + z 1 1, 1.9 ⁇ p ⁇ 2.1 and 0 ⁇ q ⁇ 0.1.
• Examples of the compound (ii) represented by the formula (2) include LiCoO 2 , LiNiO 2 , LiMnO 2 , LiMn 0.5 Ni 0.5 O 2 , LiNi 0.5 Co 0.2 Mn 0.3 O. 2 , LiNi 0.85 Co 0.10 Al 0.05 O 2 , LiNi 1/3 Co 1/3 Mn 1/3 O 2 .
• the olivine-type metal lithium salt (compound (iii)) is a compound represented by the following formula (3) or a complex thereof.
• X represents Fe (II), Co (II), Mn (II), Ni (II), V (II), or Cu (II)
• Y represents P or Si, 0 ⁇ L ⁇ 3, 1 ⁇ x 3 ⁇ 2, 1 ⁇ y 3 ⁇ 3, 4 ⁇ z 3 ⁇ 12, 0 ⁇ g ⁇ 1.
• LiFePO 4 Li 3 Fe 2 (PO 4 ) 3 , LiFeP 2 O 7 , LiMnPO 4 , LiNiPO 4 , LiCoPO 4 , Li 2 FePO 4 F, Li 2 MnPO 4 F, Li 2 NiPO 4 F, Li 2 CoPO 4 F, Li 2 FeSiO 4, Li 2 MnSiO 4, Li 2 NiSiO 4, Li 2 CoSiO 4 can be cited.
• LiMn 2 O 4 LiMn 1.5 Ni 0.5 O 4 , LiMn 1.0 Co 1.0 O 4 , LiMn 1.85 Al 0.15 O 4 , LiMn 1.9 Mg 0.1 O 4 may be mentioned.
• the lithium-containing composite oxide (I) is preferably particulate.
• the average particle diameter (D50) is preferably 0.03 to 30 ⁇ m.
• D50 is preferably 3 to 30 ⁇ m, more preferably 4 to 25 ⁇ m, and particularly preferably 5 to 20 ⁇ m.
• D50 is preferably 0.03 to 5 ⁇ m, more preferably 0.04 to 1 ⁇ m, and particularly preferably 0.05 to 0.5 ⁇ m.
• D50 is a volume-based cumulative 50% diameter which is a particle diameter at a point where the cumulative curve is 50% in a cumulative curve where the particle size distribution is obtained on a volume basis and the total volume is 100%.
• the particle size distribution is obtained from a frequency distribution and a cumulative volume distribution curve measured with a laser scattering particle size distribution measuring apparatus.
• the particle size is measured by sufficiently dispersing the powder in an aqueous medium by ultrasonic treatment or the like and measuring the particle size distribution (for example, a laser diffraction / scattering particle size distribution measuring device Partica LA-950VII manufactured by HORIBA, etc.). Used).
• the lithium-containing composite oxide (I) can be produced by mixing a coprecipitate containing a transition metal obtained by a coprecipitation method with a lithium compound and baking, hydrothermal synthesis method, sol-gel method, dry mixing A method (solid phase method), an ion exchange method, or a glass crystallization method can be appropriately used. In particular, a method of mixing and baking the coprecipitate and a lithium compound is preferable because a high discharge capacity is easily obtained.
• the coprecipitation method an alkali coprecipitation method and a carbonate coprecipitation method are preferable.
• the lithium composite oxide (I) is a compound selected from the compound (i)
• the carbonate coprecipitation method is preferable from the viewpoint that a high discharge capacity is easily obtained.
• Each of these production methods can be performed using a known method.
• the alkali coprecipitation method is a method in which an aqueous solution of a metal salt containing a transition metal element and a pH adjusting solution containing a strong alkali are continuously mixed to maintain a constant pH in the reaction solution. This is a method of depositing a hydroxide containing a metal element.
• a positive electrode active material having a high powder density of the obtained coprecipitate and excellent filling properties in the positive electrode active material layer can be obtained.
• metal salts containing transition metal elements include nitrates, acetates, chloride salts, and sulfates of transition metal elements. Since the material cost is relatively low and excellent battery characteristics are obtained, a transition metal element sulfate is preferable, and a sulfate composed of Ni sulfate, Co sulfate and Mn sulfate is more preferable.
• Examples of the sulfate of Ni include nickel (II) sulfate hexahydrate, nickel (II) sulfate heptahydrate, nickel sulfate (II) ammonium hexahydrate, and the like.
• Examples of Co sulfate include cobalt (II) sulfate heptahydrate and cobalt (II) ammonium sulfate hexahydrate.
• Examples of the sulfate of Mn include manganese sulfate (II) pentahydrate, manganese sulfate (II) ammonium hexahydrate, and the like.
• the pH of the solution during the reaction in the alkali coprecipitation method is preferably 10-12.
• An aqueous solution containing at least one selected from the group consisting of sodium hydroxide, potassium hydroxide, and lithium hydroxide is preferable as the pH adjusting solution containing a strong alkali to be added. Among these, an aqueous sodium hydroxide solution is more preferable.
• an aqueous ammonia solution or an aqueous ammonium sulfate solution may be added to the reaction solution in the alkali coprecipitation method.
• the carbonate coprecipitation method is a method in which a metal salt aqueous solution containing a transition metal element and an alkali metal carbonate aqueous solution are continuously mixed to precipitate a carbonate containing a transition metal element in a reaction solution. .
• a positive electrode active material is obtained in which the obtained coprecipitate is porous, has a high specific surface area, and exhibits a high discharge capacity.
• the metal salt containing a transition metal element used in the carbonate coprecipitation method include the same transition metal salts as those exemplified in the alkali coprecipitation method.
• the pH of the solution during the reaction in the carbonate coprecipitation method is preferably 7-9.
• the alkali metal carbonate aqueous solution is preferably an aqueous solution containing at least one selected from the group consisting of sodium carbonate, sodium hydrogen carbonate, potassium carbonate, and potassium hydrogen carbonate.
• An aqueous ammonia solution or an aqueous ammonium sulfate solution may be added to the reaction solution in the carbonate coprecipitation method for the same reason as in the alkali coprecipitation method.
• a step of removing the aqueous solution by filtration, sedimentation separation, or centrifugation.
• a pressure filter, a vacuum filter, a centrifugal classifier, a filter press, a screw press, a rotary dehydrator, or the like can be used.
• washing step it is preferable to carry out a washing step to remove impurity ions such as sodium from the obtained coprecipitate.
• the method for washing the coprecipitate include a method of repeating filtration and dispersion in ion-exchanged water.
• a lithium-containing composite oxide is obtained by mixing and calcining a coprecipitate obtained by the coprecipitation method and a lithium compound.
• the lithium compound for example, lithium carbonate, lithium hydroxide, or lithium nitrate is preferable, and lithium carbonate is more preferable because it is inexpensive.
• the firing temperature is preferably 500 to 1000 ° C. When the firing temperature is within the above range, a lithium-containing composite oxide having high crystallinity is easily obtained.
• the firing temperature is more preferably 600 to 1000 ° C., and particularly preferably 800 to 950 ° C.
• the firing time is preferably 4 to 40 hours, and more preferably 4 to 20 hours. Firing is preferably performed in an oxygen-containing atmosphere, for example, while supplying air. By firing in an oxygen-containing atmosphere, the transition metal element in the coprecipitate is sufficiently oxidized, and the crystallinity tends to be high.
• the lithium-containing composite oxide (I) is brought into contact with the cleaning liquid, and separated from the cleaning liquid after the contact to obtain the lithium-containing composite oxide (II).
• the lithium-containing composite oxide (I) includes Li that does not form the crystal structure of the lithium-containing composite oxide as an impurity.
• alkaline components such as Li, Na, K, etc. which originate in the manufacturing raw material (a coprecipitate, a lithium compound, others) of lithium containing complex oxide (I) may be contained.
• These alkali components are hereinafter referred to as free alkalis. It is considered that the free alkali is attached to the surface of the lithium-containing composite oxide in the form of hydroxide or carbonate. The free alkali can be removed from the lithium-containing composite oxide by the washing treatment. As a result, the battery characteristics of the lithium ion secondary battery using the washed lithium-containing composite oxide as the positive electrode active material can be improved.
• the cleaning liquid is not particularly limited as long as it can dissolve free alkali, and water or an acidic aqueous solution is preferable.
• a pH adjuster or the like may be included in the cleaning liquid in order to control the solubility of free alkali and improve handling.
• the cleaning solution is preferably an acidic aqueous solution in that free alkali is easily dissolved and high charge / discharge efficiency and high discharge capacity can be obtained.
• an acidic aqueous solution having a pH of 0 to 6 at 25 ° C. is preferable.
• the pH of the cleaning liquid is more preferably from 0.5 to 5, and further preferably from 1 to 4.
• the acid component contained in the cleaning liquid is preferably an acid component that does not contain F in order to facilitate separation of the cleaning liquid and the lithium-containing composite oxide (II).
• Suitable acid components contained in the cleaning liquid include lactic acid, sulfuric acid, carbonic acid, citric acid, glycolic acid, malic acid, tartaric acid, gluconic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid. Examples include acid, phthalic acid, formic acid, acetic acid, propionic acid, ascorbic acid, nitric acid, hydrochloric acid, boric acid, phosphoric acid, and perchloric acid. Lactic acid, sulfuric acid, acetic acid, or glycolic acid is more preferable in terms of handling and improving charge / discharge efficiency.
• An acid component may be used individually by 1 type, and may use 2 or more types together.
• a method for bringing the lithium-containing composite oxide (I) into contact with the cleaning liquid for example, a method in which the lithium-containing composite oxide (I) is added to the cleaning liquid and stirred and mixed can be used.
• the contact with the cleaning liquid may be performed a plurality of times.
• the temperature of the cleaning liquid brought into contact with the lithium-containing composite oxide (I) is preferably 10 to 90 ° C., more preferably 20 to 60 ° C., from the viewpoint of improving workability and charge / discharge efficiency.
• the pH of the cleaning solution is higher than 4
• the temperature is preferably 40 ° C. or higher in order to increase the solubility of lithium.
• the time for which the lithium-containing composite oxide (I) is brought into contact with the cleaning liquid is not particularly limited, but 0.5 hours or more is preferable and 1 hour or more is preferable in terms of obtaining high charge / discharge efficiency and high discharge capacity.
• the upper limit of the contact time is preferably 48 hours or less, more preferably 24 hours or less from the viewpoint of productivity.
• the relative amount (X1) of the acid component obtained by the following formula (X1) is preferably 0.005 to 0.20, and preferably 0.02 to 0.15. More preferred.
• Relative amount of acid component (X1) ⁇ Amount of acid component contained in cleaning solution (mole) / Total amount of transition metal element contained in lithium-containing composite oxide (I) (mole) ⁇ ⁇ ⁇ valence of acid component Absolute value ⁇ (X1)
• the relative amount (X1) of the acid component is a molar ratio of the amount of the acid component (unit: mol) contained in the cleaning liquid to the total amount (unit: mol) of the transition metal element contained in the lithium-containing composite oxide (I).
• the value obtained by multiplying the absolute value of the valence of the acid component is not less than the lower limit of the above range, high charge / discharge efficiency and high discharge capacity are obtained, and when it is not more than the upper limit, elution of the transition metal component is small and the yield is increased.
• the cleaning liquid from which the lithium-containing composite oxide (II) is removed after washing (hereinafter referred to as waste liquid), at least lithium is dissolved, and further, the transition metal contained in the lithium-containing composite oxide (I) is dissolved. Also good.
• the waste liquid is also referred to as a filtrate.
• the lithium elution rate determined by the following formula (X2) (hereinafter sometimes referred to as “lithium elution rate (X2)”) is preferably 0.2 to 10%, more preferably 1 to 6%. preferable. When the lithium elution rate (X2) is within the above range, high charge / discharge efficiency and high discharge capacity can be obtained.
• Lithium elution rate (X2) ⁇ Amount of Li contained in waste liquid (mol) / Amount of Li contained in lithium-containing composite oxide (I) ⁇ ⁇ 100 (X2)
• the lithium elution rate (X2) is the ratio of the amount of Li dissolved in the cleaning liquid to the total Li contained in the lithium-containing composite oxide (I).
• the amount of Li contained in the waste liquid and the lithium-containing composite oxide (I) is calculated by measurement by inductively coupled plasma (ICP) emission spectroscopy.
• ICP inductively coupled plasma
• transition metal elution rate (X3)) obtained by the following formula (X3) is preferably 0 to 2%, and preferably 0 to 1.5%. Is more preferable. If the transition metal elution rate (X3) is within the above range, the transition metal component is less eluted and the yield is increased.
• Transition metal elution rate (X3) ⁇ total amount of transition metal element contained in waste liquid (mol) / total amount of transition metal element contained in lithium-containing composite oxide (I) ⁇ ⁇ 100 (X3)
• the transition metal elution rate (X3) is a ratio of the total amount of transition metal elements dissolved in the cleaning liquid to the total amount of transition metal elements contained in the lithium-containing composite oxide (I).
• the content of the transition metal element contained in the waste liquid and the lithium-containing composite oxide (I) is calculated by measurement by inductively coupled plasma (ICP) emission spectroscopy.
• the pH of the waste liquid at 25 ° C. is preferably 4.5 to 12.5, more preferably 5.5 to 10.
• the pH of the waste liquid at 25 ° C. is preferably 7 or more.
• the lithium-containing composite oxide (II) is obtained by separating from the cleaning liquid.
• a separation method general solid-liquid separation can be used, and examples thereof include filtration, sedimentation separation, and centrifugation.
• an acidic aqueous solution is used as the cleaning liquid, it is preferable to wash the surface of the lithium-containing composite oxide (II) with water or the like when separating from the cleaning liquid.
• the lithium-containing composite oxide (II) is preferably separated from the cleaning liquid and then heat-dried to remove excess moisture, adsorbate and the like. Thereby, it becomes easy to handle lithium containing complex oxide (II), and the process after process (II) can be performed efficiently.
• the heating temperature is preferably 40 to 300 ° C, more preferably 60 to 200 ° C.
• the heating time is not particularly limited, and is preferably 0.5 to 30 hours, for example, and more preferably 1 to 20 hours. When the heating temperature is within the above range, it can be efficiently dried.
• step (II) of this production method the lithium-containing composite oxide obtained in step (I) is brought into contact with the composition (1) and the composition (2) to contact the lithium-containing composite oxide. (III) is obtained. If the positive electrode active material obtained through this step is used, the charge / discharge efficiency and cycle characteristics of the lithium ion secondary battery can be improved.
• the anion (A) contained in the composition (1) extracts Li from the lithium-containing composite oxide (II) and improves the charge / discharge efficiency of the lithium ion secondary battery. If the metal element (m) contained in the composition (2) is present on the surface, elution of the transition metal from the lithium-containing composite oxide can be suppressed, and the cycle characteristics of the lithium ion secondary battery are improved.
• the anion (A) contained in the composition (1) reacts with the free alkali to extract the Li from the anion (A). It is possible to prevent the effect from being reduced.
• the order of contact is not limited.
• composition examples include an embodiment in which one composition is brought into contact with the other composition and the other composition is alternately brought into contact with each other a plurality of times.
• the composition (1) and the composition (2) are simultaneously contacted.
• the composition (1) and the composition (2) are mixed in advance and then contacted with the lithium-containing composite oxide (II). And the like.
• the composition (1) is brought into contact with the lithium-containing composite oxide (II) after contacting the composition (2). It is particularly preferable to set the order of contact.
• the step (II) as a method of bringing the lithium-containing composite oxide (II) into contact with the composition (1) and the composition (2), an immersion method, a spray method (spray method), a coating method, or the like can be used.
• the spray coating method is preferred.
• the spray coating method is a method in which the composition (1) and the composition (2) are sprayed onto the lithium-containing composite oxide (II).
• the process is simple and the coating layer is uniformly formed on the surface of the lithium-containing composite oxide. It is preferable because it can be formed.
• the composition (1) and the composition (2) are sprayed and mixed with the lithium-containing composite oxide (II) while stirring the particles of the lithium-containing composite oxide (II). It is preferable.
• the amount of the composition (1) and the composition (2) used for contact with the lithium-containing composite oxide (II) is an amount that can be absorbed and adhered by the lithium-containing composite oxide (II). Is preferred. If the lithium-containing composite oxide (II) can be absorbed and adhered, the composition (1) and the composition (2) remaining after contacting the composition (1) and the composition (2) are eliminated. This is preferable because it eliminates the process to process the process.
• the contact temperature between the lithium-containing composite oxide (II), the composition (1) and the composition (2) is preferably 10 to 100 ° C. The contact time is preferably 5 minutes to 10 hours.
• composition (1) An aqueous solution containing a monoatomic or polyatomic anion (A) containing at least one element (a) selected from the group consisting of S, P, F, and B.
• the anion (A) include SO 4 2 ⁇ , SO 3 2 ⁇ , S 2 O 3 2 ⁇ , SO 6 2 ⁇ , SO 8 2 ⁇ , PO 4 3 ⁇ , P 2 O 7 4 ⁇ , PO 3 3. — , PO 2 3 ⁇ , F ⁇ , BO 3 3 ⁇ , BO 2 ⁇ , B 4 O 7 2 ⁇ , B 5 O 8 ⁇ are preferable.
• SO 4 2 ⁇ , PO 4 3 ⁇ , or F ⁇ is more preferable from the viewpoint of stability and handleability.
• the anion (A) is more preferably F 2 -in that a high discharge capacity can be obtained.
• the composition (1) preferably contains the element (a) and is dissolved in water as a solvent, which is a water-soluble compound (1) that is dissociated in an aqueous solution to generate an anion (A).
• a water-soluble compound (1) that is dissociated in an aqueous solution to generate an anion (A).
• the solubility in distilled water at 25 ° C. (the mass [g] of the solute dissolved in 100 g of the saturated solution) is referred to as water solubility, and the solubility is 0 to 2. Slightly soluble.
• Preferable examples of the water-soluble compound (1) having a solubility exceeding 2 include H 2 SO 4 , H 2 SO 3 , H 2 S 2 O 3 , H 2 SO 6 , H 2 SO 8 , and H 3 PO 4.
• a salt rather than an acid in terms of handleability and safety.
• An ammonium salt is particularly preferable in that it is decomposed and removed when heated.
• (NH 4 ) 2 SO 4 , (NH 4 ) HSO 4 , (NH 4 ) 3 PO 4 , (NH 4 ) 2 HPO 4 , (NH 4 ) H 2 PO 4 , NH 4 F and the like are preferable. .
• the solvent of the composition (1) may contain one or both of a water-soluble alcohol and a polyol as long as the solubility of the water-soluble compound (1) is not impaired.
• a water-soluble alcohol include methanol, ethanol, 1-propanol, and 2-propanol.
• the polyol include ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, polyethylene glycol, butanediol, and glycerin.
• the total content of the water-soluble alcohol and the polyol contained in the solvent is preferably 0 to 20%, more preferably 0 to 10% with respect to the total mass of the solvent.
• the solvent is particularly preferably water only.
• the composition (1) may contain a pH adjuster in order to adjust the solubility of the water-soluble compound (1).
• a pH adjuster those that volatilize or decompose when heated in a later step are preferable.
• an organic acid such as acetic acid, citric acid, lactic acid, formic acid, maleic acid, oxalic acid, or ammonia is preferable.
• the content of the water-soluble compound (1) is preferably 0.5 to 30%, particularly preferably 2 to 20% in terms of anion (A), based on the total mass of (1) in the composition. If the water-soluble compound (1) is 0.5% or more, it is preferable because the solvent is easily removed by heating in the subsequent step. Moreover, if it is 30% or less, the viscosity of a composition (1) will become an appropriate range, and it is preferable at the point which is easy to make lithium containing complex oxide (II) and a composition (1) contact uniformly.
• the amount of the composition (1) brought into contact with the lithium-containing composite oxide (II) is such that the relative amount (Xa) of the anion (A) determined by the following formula (Xa) is within the range of 0.001 to 0.15. It is preferable that The relative amount (Xa) of the anion (A) is the amount of each anion (A) contained in the composition (1) with respect to the total amount (unit: mole) of the transition metal element contained in the lithium-containing composite oxide (I). ) Is multiplied by the absolute value of the valence of each anion (A).
• the relative amount (Xa) of the anion (A) is 0.001 or more, the charge / discharge efficiency is easily improved, and when it is 0.15 or less, capacity reduction due to impurity generation hardly occurs.
• the value of the relative amount (Xa) of the anion (A) is more preferably within the range of 0.003 to 0.12, and particularly preferably within the range of 0.005 to 0.09.
• Relative amount of anion (A) (Xa) ⁇ amount (mole) of anion (A) contained in composition (1) / total amount of transition metal element contained in lithium-containing composite oxide (I) (mole) ) ⁇ ⁇ ⁇ the absolute value of the valence of the anion (A) ⁇ (Xa)
• the relative amount (Xa) of the anions (A) is included in the composition (1). The sum of all anions. That is, for each anion, the “relative amount of anion (A1)”, “relative amount of anion (A2)”, and the like are obtained by the above formula (Xa), and the total of these is preferably in the above-described range.
• composition (2) in the present invention includes Li, Mg, Ca, Sr, Ba, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, A single atom or complex of at least one metal element (m) selected from the group consisting of Zn, Al, Ga, In, Sn, Sb, Bi, La, Ce, Pr, Nd, Gd, Dy, Er, and Yb An aqueous solution containing the cation (M).
• the cation (M) is preferably a monoatomic ion of the metal element (m).
• the metal element (m) Al, Nb, or Zr is preferable.
• the cation (M) Al 3+ , Nb 5+ , Nb 3+ , or Zr 4+ is preferable.
• the metal element (m) is preferably Al, and the cation (M) is more preferably Al 3+ .
• the composition (2) preferably has a metal element (m) and a water-soluble compound (2) that generates a cation (M) in an aqueous solution dissolved in water as a solvent.
• the water-soluble compounds (2) include inorganic salts such as nitrates, sulfates and chlorides of metal elements (m), acetates, citrates, maleates, formates, lactates, lactates, sulphate
• organic salts such as acid salts, organic complexes, and ammine complexes.
• nitrates, organic acid salts, organic complexes, or ammine complexes are particularly preferable because they are easily decomposed by heat and have high solubility in a solvent.
• Preferred examples of the water-soluble compound (2) include ammonium zirconium carbonate, ammonium zirconium halide, zirconium acetate, zirconium nitrate, aluminum nitrate, aluminum acetate, aluminum oxalate, aluminum citrate, aluminum lactate, basic aluminum lactate, malein Examples thereof include aluminum oxide, niobium nitrate, niobium acetate, niobium citrate, niobium maleate, niobium formate, niobium lactate, niobium oxalate, and ammonium niobium oxalate.
• the solvent of the composition (2) one or both of a water-soluble alcohol and a polyol similar to those of the composition (1) may be added as long as the solubility of the water-soluble compound (2) is not impaired. Moreover, the content is the same as that of the composition (1). Furthermore, in order to adjust the solubility of the water-soluble compound (2), the composition (2) may contain the same pH adjuster as that of the composition (1).
• the content of the aqueous solution compound (2) is preferably from 0.5 to 30%, particularly preferably from 2 to 20%, in terms of metal element (m), based on the total mass of (2) in the composition. If the water-soluble compound (2) is 0.5% or more, it is preferable because the solvent can be easily removed by heating in a later step. Moreover, if it is 30% or less, the viscosity of a composition (2) will become an appropriate range, and it is preferable at the point which is easy to make lithium containing complex oxide (II) and a composition (2) contact uniformly.
• the amount of the composition (2) brought into contact with the lithium-containing composite oxide (II) is such that the relative amount (Xm) of the metal element (m) determined by the following formula (Xm) is within the range of 0.001 to 0.15. It is preferable that The relative amount (Xm) of the metal element (m) is the amount of each cation (M) contained in the composition (2) with respect to the total amount (unit: mol) of the transition metal element contained in the lithium-containing composite oxide (I). ) Is a value obtained by multiplying the molar ratio of the quantity (unit: mole) by the absolute value of the valence of the cation (M).
• the value of the relative amount (Xm) of the metal element (m) is 0.001 or more, the effect of improving the cycle characteristics is increased, and when the value is 0.15 or less, capacity reduction due to impurity generation hardly occurs.
• the value of the relative amount (Xm) of the metal element (m) is more preferably within the range of 0.003 to 0.12, and particularly preferably within the range of 0.005 to 0.09.
• Relative amount (Xm) of metal element (m) ⁇ amount (mol) of each cation (M) contained in composition (2) / total amount of transition metal element contained in lithium-containing composite oxide (I) ( Mol) ⁇ ⁇ ⁇ the absolute value of the valence of each cation (M) ⁇ (Xm)
• the relative amount (Xm) of the metal element (m) It is the total value of metal elements. That is, for each of the cation (M1) containing the metal element (m1), the cation (M2) ...
• the amount of the composition (1) and the amount of the composition (2) that are brought into contact with the lithium-containing composite oxide (II) are the relative amount of the metal element (m) (Xm) / the relative amount of the anion (A).
• the ratio (Xm / Xa) of both represented by (Xa) is preferably 0.1 to 10.
• the ratio (Xm / Xa) of the two is more preferably 0.2 to 5, and further preferably 0.3 to 3. When the ratio (Xm / Xa) of the two is within the above range, a positive electrode active material having a high discharge capacity and high cycle characteristics is easily obtained.
• step (III) of this production method the lithium-containing composite oxide (III) obtained in step (II) is heated. By this heating, volatile impurities such as water and organic components contained in the lithium-containing composite oxide (III), the composition (1), and the composition (2) are removed, and a coating layer is formed on a part of the surface. The lithium-containing composite oxide is obtained. In step (III), it is preferable to remove most of the water in advance by drying the lithium-containing composite oxide (III) at 40 to 200 ° C. for 0.5 to 8 hours before heating.
• the heating in step (III) is preferably performed in an oxygen-containing atmosphere.
• the heating temperature is preferably 250 to 700 ° C, more preferably 350 to 600 ° C.
• a coating layer can be favorably formed as heating temperature is 250 degreeC or more. Further, since volatile impurities such as residual moisture are reduced, a decrease in cycle maintenance rate can be suppressed.
• the heating temperature is 700 ° C. or lower, the metal element (m) is difficult to diffuse inside the positive electrode active material, and the battery capacity can be prevented from decreasing due to the diffusion of the metal element (m).
• the heating temperature is preferably 250 ° C. to 550 ° C., more preferably 350 to 500 ° C.
• the heating temperature is 550 ° C. or lower, the coating layer is difficult to crystallize.
• the heating time is preferably 0.1 to 24 hours, more preferably 0.5 to 18 hours, and particularly preferably 1 to 12 hours. When the heating time is in the above range, the coating layer is easily formed satisfactorily.
• the pressure at the time of heating is not specifically limited, Normal pressure or pressurization is preferable, and normal pressure is particularly preferable.
• the coating layer is made of a compound containing the element (a), a compound containing the metal element (m), a compound containing the element (a) and the metal element (m), or a mixture thereof.
• the coating layer preferably contains at least a hardly soluble compound containing the element (a) and the metal element (m).
• the compound containing the element (a) include a salt composed of the element (a) and an alkali metal.
• the salt include LiF, Li 3 PO 4 , Li 2 SO 4 , NaF, and KF.
• the compound containing the metal element (m) include an oxide or hydroxide of the metal element (m). Examples of the oxide include Al 2 O 3 and ZrO 2 .
• hydroxide examples include Al (OH) 3 and Zr (OH) 4 .
• specific examples of the compound containing the element (a) and the metal element (m) include BaSO 4 , CaSO 4 , SrSO 4 , Al 2 (SO 4 ) 3 , Zr (SO 4 ) 2 , CePO 4 , and BiPO 4.
• Al 2 (SO 4 ) 3 , AlPO 4 , AlF 3 , Zr (SO 4 ) 2 , or ZrF 4 is preferable, Al 2 (SO 4 ) 3 or AlF 3 is more preferable, and AlF 3 Is particularly preferred.
• the method for producing a positive electrode for a lithium ion secondary battery according to the present invention includes a step of producing the positive electrode active material for a lithium ion secondary battery, and a positive electrode active material layer including the obtained positive electrode active material, a binder, and a conductive material. Forming on the positive electrode current collector.
• the step of forming the positive electrode active material layer can be performed using a known method.
• a positive electrode active material, a conductive material, and a binder are dissolved or dispersed in a medium to obtain a slurry, or a positive electrode active material, a conductive material, and a binder are kneaded with a medium to obtain a kneaded product.
• the positive electrode active material layer can be formed by coating the obtained slurry or kneaded material on the positive electrode current collector (positive electrode surface).
• Examples of the conductive material include carbon black such as acetylene black, graphite, and ketjen black. One type of conductive material may be used, or two or more types may be used.
• Examples of the binder include fluororesins, polyolefins, polymers having an unsaturated bond and copolymers thereof, acrylic acid polymers such as acrylic acid copolymers and methacrylic acid copolymers, and copolymers thereof.
• Examples of the fluororesin include polyvinylidene fluoride and polytetrafluoroethylene.
• Examples of the polyolefin include polyethylene and polypropylene.
• a polymer having an unsaturated bond and a copolymer thereof a polymer having an unsaturated bond such as styrene-butadiene rubber, isoprene rubber, butadiene rubber, and the copolymer thereof, and as a positive electrode current collector, an aluminum foil or An aluminum alloy foil is mentioned.
• the method for producing a lithium ion secondary battery according to the present invention includes a step of producing the above-described positive electrode for a lithium ion secondary battery, and a lithium ion secondary battery using the obtained positive electrode for a lithium ion secondary battery, a negative electrode, a nonaqueous electrolyte, and a separator.
• the process which comprises a lithium ion secondary battery can be performed using a well-known method.
• the negative electrode is obtained by forming a negative electrode active material layer containing a negative electrode active material on a negative electrode current collector.
• the slurry can be prepared by kneading a negative electrode active material with an organic solvent, and applying the prepared slurry to a negative electrode current collector, drying, and pressing.
• the negative electrode current collector for example, nickel foil, copper foil or the like can be used.
• the negative electrode active material may be any material that can occlude and release lithium ions at a relatively low potential.
• a lithium metal for example, a lithium metal, a lithium alloy, a carbon material, an oxide mainly composed of a metal of periodic table 14 or 15, Carbon compounds, silicon carbide compounds, silicon oxide compounds, titanium sulfide, boron carbide compounds, and the like can be used.
• Carbon materials used for the negative electrode active material include non-graphitizable carbon, artificial graphite, natural graphite, pyrolytic carbons, cokes, graphites, glassy carbons, organic polymer compound fired bodies, carbon fibers, activated carbon And carbon blacks.
• Examples of the cokes include pitch coke, needle coke, and petroleum coke.
• Examples of the fired organic polymer compound include those obtained by firing and carbonizing a phenol resin, a furan resin, or the like at an appropriate temperature.
• Examples of the metal of Group 14 of the periodic table include Si and Sn. Among these, Si is preferable as the metal of Group 14 of the periodic table.
• nonaqueous electrolyte examples include a nonaqueous electrolytic solution in which an electrolyte salt is dissolved in an organic solvent, an inorganic solid electrolyte, and a solid or gel polymer electrolyte in which an electrolyte salt is mixed or dissolved.
• organic solvent known organic solvents for non-aqueous electrolytes can be employed.
• the organic solvent is preferably a cyclic carbonate such as propylene carbonate, or a chain carbonate such as dimethyl carbonate or diethyl carbonate.
• One organic solvent may be used, or two or more organic solvents may be used.
• Examples of the inorganic solid electrolyte include lithium nitride and lithium iodide.
• Examples of the polymer compound used in the solid polymer electrolyte in which the electrolyte salt is mixed or dissolved include polyethylene oxide, polypropylene oxide, polyphosphazene, polyaziridine, polyethylene sulfide, polyvinyl alcohol, polyvinylidene fluoride, polyhexafluoropropylene, And their derivatives, mixtures, and complexes.
• Examples of the polymer compound used in the gel polymer electrolyte in which the electrolyte salt is mixed or dissolved include a fluorine polymer compound, polyacrylonitrile, a copolymer of polyacrylonitrile, polyethylene oxide, a copolymer of polyethylene oxide, and the like. Can be mentioned.
• Examples of the fluorine-based polymer compound include poly (vinylidene fluoride) and poly (vinylidene fluoride-co-hexafluoropropylene).
• the matrix of the gel electrolyte is preferably a fluorine-based polymer compound from the viewpoint of stability against redox reaction.
• the electrolyte salt known ones used in lithium ion secondary batteries can be used, and examples thereof include LiClO 4 , LiPF 6 , LiBF 4 , CF 3 SO 3 Li, and the like.
• the separator include a microporous polyolefin film typified by polyethylene and polypropylene, a film made of a copolymer of polyvinylidene fluoride and hexafluoropropylene, inorganic particles on the surface of the microporous polyolefin film, an aramid resin, a fluororesin, etc. The composite film which apply
• the shape of the lithium ion secondary battery is not particularly limited, and shapes such as a coin shape, a sheet shape (film shape), a folded shape, a wound type bottomed cylindrical shape, a button shape, and the like can be appropriately selected depending on the application.
• a raw material solution consisting of an aqueous salt solution was prepared.
• 401 g of distilled water was added to 99 g of ammonium sulfate and dissolved uniformly to obtain an aqueous ammonium sulfate solution.
• 1900 g of distilled water was added to 1 g of sodium carbonate and dissolved uniformly to obtain a mother liquor.
• an aqueous carbonate solution was added so as to keep the pH in the reaction vessel at 8.0. Further, nitrogen gas was flowed into the reaction vessel at a flow rate of 0.5 L / min so that the deposited transition metal carbonate was not oxidized.
• the obtained coprecipitate was repeatedly washed with pressure filtration and dispersed in distilled water to remove impurity ions. When the electrical conductivity of the filtrate became less than 100 ⁇ S / cm, the washing was finished and dried at 120 ° C. for 15 hours. When the total content of transition metals contained in the coprecipitate after washing and drying was determined by back titration with a ZINCON indicator, EDTA and an aqueous zinc chloride solution, it was 8.36 mol / kg.
• Li-containing composite oxide (I ) 300 g of the coprecipitate and 139.5 g of lithium carbonate having a lithium content of 26.96 mol / kg are mixed and fired at 880 ° C. for 16 hours in an oxygen-containing atmosphere to obtain a lithium-containing composite oxide (I ) Was obtained.
• the amounts of Li, Ni, Co and Mn contained in the lithium-containing composite oxide (I) were measured by ICP.
• the molar ratio of Li: Ni: Co: Mn was 1.5: 0.16: 0.17: 0.67.
• the composition of the lithium-containing composite oxide (I) can be expressed as Li (Li 0.20 Ni 0.128 Co 0.136 Mn 0.536 ) O 2 .
• the average particle diameter D50 of this lithium-containing composite oxide (I) was 10.8 ⁇ m.
• Example 1 [Step (I)] In a 1000 mL plastic container, 20 g of lactic acid (purity 90%) and 800 g of distilled water were added and mixed to obtain a cleaning solution. The pH of the cleaning solution was 2.3. Furthermore, 200 g of lithium-containing composite oxide (I) was added to the cleaning solution, and the mixture was stirred for 3 minutes using a stirring blade. Next, the stirring blade was taken out, the plastic container was covered, and the mixture was mixed for 24 hours at a rotation speed of 20 rpm using a roller mixer. Mixing was performed at room temperature (25 ° C.). The relative amount (X1) of the acid component calculated by the formula (X1) was 0.11.
• the pH of the filtrate was 6.3.
• the lithium elution rate (X2) calculated by the formula (X2) was 3.7%
• the transition metal elution rate (X3) calculated by the formula (X3) was 0.7%.
• composition (2) An aluminum lactate aqueous solution (composition (2)) was prepared by adding 5.8 g of distilled water to 4.2 g of a basic aluminum lactate aqueous solution having an Al content with respect to the mass of the aqueous solution of 8.8% in terms of Al 2 O 3. ) was prepared.
• the metal element (m) content (Al equivalent concentration) relative to the mass of the aluminum lactate aqueous solution (composition (2)) was 3.7%.
• 8.38 g of distilled water was added to 1.62 g of ammonium fluoride (NH 4 F) and mixed to prepare an aqueous ammonium fluoride solution (composition (1)).
• Aqueous ammonium fluoride solution (composition (1)) anions (A) in terms of the concentration to the mass of (F - in terms of concentration) was 8.3%. While stirring 8 g of the lithium-containing composite oxide (II) obtained in the step (I), 0.64 g of the aqueous aluminum lactate solution (composition (2)) was sprayed by a spray coating method to obtain a lithium-containing composite oxide. (II) and the aqueous aluminum lactate solution were brought into contact with mixing.
• composition (1) an ammonium fluoride aqueous solution
• composition (2) an ammonium fluoride aqueous solution
• the lithium-containing composite oxide (II), the aluminum lactate aqueous solution, and the ammonium fluoride aqueous solution are mixed and brought into contact with each other.
• Containing complex oxide (III) was obtained.
• the amount of the composition (1) brought into contact with the lithium-containing composite oxide (II) is such that the relative amount (Xa) of the anion (A) obtained by the formula (Xa) is 0.038. Amount.
• the amount of the composition (2) brought into contact with the lithium-containing composite oxide (II) is such that the relative amount (Xm) of the metal element (m) obtained by the formula (Xm) is 0.019. .
• the valence of the metal element Al used in this example is +3.
• Step (III) The obtained lithium-containing composite oxide (III) is dried at 80 ° C. for 4 hours and then heated at 450 ° C. for 5 hours in an oxygen-containing atmosphere, and Al and F are partially contained on the surface of the lithium-containing composite oxide particles.
• a positive electrode active material composed of particles having a coating layer was obtained.
• Example 2 In Example 1, the spray amount of the aqueous ammonium fluoride solution was changed to 0.32 g, and the relative amount (Xa) of the anion (A) was set to 0.019. Others were carried out similarly to Example 1, and obtained the positive electrode active material which consists of a particle
• Example 4 Step (I) was carried out in the same manner as in Example 1. Distilled water (3.26 g) was added to and mixed with 1.75 g of an aqueous zirconium carbonate solution having a Zr content of 20.7% in terms of ZrO 2 with respect to the mass of the aqueous solution to prepare an ammonium zirconium carbonate (composition (2)).
• the content (Zr equivalent concentration) of the metal element (m) with respect to the mass of the ammonium zirconium carbonate aqueous solution (composition (2)) was 7.2%.
• composition (2) aqueous ammonium zirconium carbonate solution
• composition (1) an aqueous ammonium fluoride solution
• the lithium-containing composite oxide (II), zirconium ammonium carbonate, and an aqueous ammonium fluoride solution are mixed and brought into contact with each other. Containing complex oxide (III) was obtained.
• Step (III) was carried out in the same manner as in Example 1 to obtain a positive electrode active material comprising particles having a coating layer containing Zr and F on a part of the surface of the lithium-containing composite oxide particles.
• Example 5 Lithium-containing composite oxide (II) washed in the same manner as in step (I) of Example 1 was used as the positive electrode active material. Steps (II) and (III) were not performed.
• step (II) of Example 1 spray coating of an aqueous ammonium fluoride solution (composition (1)) was not performed. Otherwise, in the same manner as in Example 1, a positive electrode active material composed of particles having a coating layer containing Al on a part of the surface of the lithium-containing composite oxide particles was obtained.
• Example 7 In Example 1, the spray amount of the aluminum lactate aqueous solution was changed to 1.28 g, and the relative amount (Xm) of the metal element (m) was set to 0.038.
• step (II) the aqueous ammonium fluoride solution (composition (1)) was not spray-coated. Otherwise, in the same manner as in Example 1, a positive electrode active material composed of particles having a coating layer containing Al on a part of the surface of the lithium-containing composite oxide particles was obtained.
• Example 8 In Example 1, the step (I) was not performed, and the lithium-containing composite oxide (I) was used in the step (II). Otherwise, in the same manner as in Example 1, a positive electrode active material comprising particles having a coating layer containing Al and F on a part of the surface of the lithium-containing composite oxide particles was obtained. (Example 9) In Example 6, the step (I) was not performed, and the lithium-containing composite oxide (I) was used in the step (II). Otherwise, in the same manner as in Example 6, a positive electrode active material composed of particles having a coating layer containing Al on a part of the surface of the lithium-containing composite oxide particles was obtained.
• step (II) of Example 1 spray coating of the aqueous aluminum lactate solution (composition (2)) was not performed. Otherwise, in the same manner as in Example 1, a positive electrode active material composed of particles having a coating layer containing F on a part of the surface of the lithium-containing composite oxide particles was obtained.
• Example 11 In the step (II) of Example 3, the aluminum lactate aqueous solution (composition (2)) was not spray-coated. Otherwise, in the same manner as in Example 3, a positive electrode active material composed of particles having a coating layer containing F on a part of the surface of the lithium-containing composite oxide particles was obtained.
• step (I) was not performed. Otherwise, in the same manner as in Example 4, a positive electrode active material composed of particles having a coating layer containing Zr and F on the surface of the lithium-containing composite oxide particles was obtained.
• Step (I) of Example 1 0.5 g of lactic acid (purity 90%) and 40 g of distilled water were added to a 50 mL screw tube bottle and mixed to obtain a washing solution. The pH of the cleaning solution was 2.4. Furthermore, 10 g of lithium-containing composite oxide (A) was added and stirred for 3 minutes using a stirrer. Next, the stirrer chip was taken out, the plastic container was covered, and mixed for 24 hours at a rotation speed of 20 rpm using a roller mixer. Mixing was performed at room temperature (25 ° C.). The relative amount (X1) of the acid component calculated by the formula (X1) was 0.05.
• Steps (II) and (III) were carried out in the same manner as in Example 1 to obtain a positive electrode active material comprising particles having a coating layer containing Al and F on a part of the surface of the lithium-containing composite oxide particles.
• Example 13 the cleaning liquid in step (I) was changed as shown in Table 2. Except this, Step (II) and Step (III) were carried out in the same manner as in Example 1 to obtain a positive electrode active material comprising particles having a coating layer containing Al and F on a part of the surface of the lithium-containing composite oxide particles.
• a cleaning liquid was prepared by mixing 1.5 g of lactic acid (purity 90%) and 40 g of distilled water.
• a cleaning liquid was prepared by mixing 0.3 g of sulfuric acid (purity 95%) and 40 g of distilled water.
• Example 16 a mixture of 0.6 g of sulfuric acid (purity 95%) and 40 g of distilled water was used as the cleaning liquid.
• Example 17 a mixture of 0.6 g of acetic acid and 40 g of distilled water was used as the cleaning liquid.
• Example 18 a mixture of 0.9 g of acetic acid and 40 g of distilled water was used as the cleaning liquid.
• Example 19 In the step (I) of Example 1, 1 g of lactic acid (purity 90%) and 35 g of distilled water were mixed in a 50 mL screw tube bottle to prepare a washing solution. The pH of the cleaning solution was 2.3. Furthermore, 20 g of lithium-containing composite oxide (I) was added and stirred for 3 minutes using a stirrer. Next, the stirrer chip was taken out, the plastic container was covered, and mixed for 24 hours at a rotation speed of 20 rpm using a roller mixer. Mixing was performed at room temperature (25 ° C.). The relative amount (X1) of the acid component calculated by the formula (X1) was 0.05.
• Steps (II) and (III) were carried out in the same manner as in Example 1 to obtain a positive electrode active material comprising particles having a coating layer containing Al and F on a part of the surface of the lithium-containing composite oxide particles.
• Step (I) of Example 1 40 g of distilled water was used as a cleaning liquid.
• the pH of the cleaning solution was 6.7.
• This washing liquid was set to 80 ° C., 10 g of lithium-containing composite oxide (A) was added, and the mixture was allowed to stand for 15 hours while maintaining the liquid temperature at 80 ° C.
• filtration was performed, and the lithium-containing composite oxide (II) was obtained by drying at 80 ° C. for 15 hours.
• the pH of the filtrate was 12.3.
• the contents of lithium and transition metals (total of Ni, Co, and Mn) contained in the filtrate were measured by ICP.
• the lithium elution rate (X2) determined by the formula (X2) was 0.2.
• Steps (II) and (III) were carried out in the same manner as in Example 1 to obtain a positive electrode active material comprising particles having a coating layer containing Al and F on a part of the surface of the lithium-containing composite oxide particles.
• Examples 1 to 12 are shown in Table 1, and the conditions of Examples 1 to 7 and 13 to 20 are shown in Table 2.
• this slurry was applied on one side to a 20 ⁇ m thick aluminum foil (positive electrode current collector) using a doctor blade. And after drying at 120 degreeC, roll press rolling was performed twice and the positive electrode body sheet
• a lithium-containing composite oxide (I) was used as a positive electrode active material, and a positive electrode sheet was produced in the same manner as described above.
• Example 1 contact with the cleaning liquid (step (I)) and coating (steps (II) and (III)) were performed, and the composition (1) and the composition (2) were used as the coating liquid.
• Examples 1 to 4 and Examples 13 to 20 are excellent in initial efficiency and cycle maintenance ratio as compared to Reference Example 1 in which neither contact with the cleaning liquid nor coating was performed.
• the effect obtained by the present invention is a synergistic effect that is superior to the effect of only the contact with the cleaning liquid and the effect of only the coating, and is an unpredictable effect. That is, in Example 5 in which only contact with the cleaning liquid was performed, the initial efficiency was improved as compared with Reference Example 1, but the cycle maintenance ratio was the same.
• Example 1 in which contact with the cleaning liquid and coating were performed, not only the initial efficiency but also the cycle maintenance ratio were improved as compared with Example 8 in which only coating was performed.
• Example 9 coated with only the composition (2) without contact with the cleaning liquid improved the cycle retention rate as compared with Reference Example 1, but had the same initial efficiency. From this result, it is predicted that when the coating step using only the composition (2) is added, the cycle retention rate is improved while maintaining the initial efficiency. However, Example 6 in which a coating step using only the composition (2) was added after contact with the cleaning liquid improved the cycle retention rate as compared with Example 5, but decreased the initial efficiency.

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• 2014
  • 2014-06-26 CN CN201480038363.2A patent/CN105378986B/zh active Active
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• 2015
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