Positive electrode active material for nonaqueous electrolyte secondary batteries, method for producing same, and nonaqueous electrolyte secondary battery

Patent metadata

Field	Value
Publication number	US-2020119350-A1
Application number	US-201816622979-A
Country	US
Kind code	A1
Filing date	Jun 25, 2018
Priority date	Jun 28, 2017
Publication date	Apr 16, 2020
Grant date	—

Abstract

Provided is a positive electrode active material for a nonaqueous electrolyte secondary battery including a LiNi composite oxide having low internal resistance and excellent thermal stability. The positive electrode active material is obtained by performing a water washing process using a water spray on a LiNi composite oxide powder obtained by a firing step until the filtrate has an electric conductivity of 30 to 60 mS/cm, and then dried, where the LiNi composite oxide is represented by the composition formula (1): LibNi1−aM1aO2, where M1 represents at least one kind of element selected from transition metal elements other than Ni, group 2 elements, and group 13 elements, and 0.01≤a≤0.5, and 0.85≤b≤1.05.

First claim

1 . A positive electrode active material for a nonaqueous electrolyte secondary battery comprising a lithium nickel composite oxide represented by composition formula (1):
Li b Ni 1−a M1 a O 2 , where M1 represents at least one kind of element selected from transition metal elements other than Ni, group 2 elements, and group 13 elements, 0.01≤a≤0.5, and 0.85≤b≤1.05, and having a specific surface area in a range of 0.5 m 2 /g to 2.05 m 2 /g and a carbon content of 0.08% by mass or less with respect to a total amount of the lithium nickel composite oxide.

2 . The positive electrode active material for a nonaqueous electrolyte secondary battery according to claim 1 , wherein a lithium amount of a lithium compound present on a surface of the lithium nickel composite oxide is 0.10% by mass or less with respect to the total amount of the lithium nickel composite oxide.

3 . The positive electrode active material for a nonaqueous electrolyte secondary battery according to claim 1 , wherein a moisture content of the lithium nickel composite oxide powder is 0.2% by mass or less.

4 . The positive electrode active material for a nonaqueous electrolyte secondary battery according to claim 1 , wherein the composition formula (1) is a composition formula (2):
Li b Ni 1−x−y−z Co x Al y M2 z O 2 , where M2 represents at least one kind of element selected from a group of Mn, Ti, Ca and Mg, 0.85≤b≤1.05, 0.05≤x≤0.30, 0.01≤y≤0.1, and z is 0≤z≤0.05.

5 . The positive electrode active material for a nonaqueous electrolyte secondary battery according to claim 1 , wherein the carbon content is in a range of 0.01% by mass to 0.04% by mass.

6 . The positive electrode active material for a nonaqueous electrolyte secondary battery according to claim 2 , wherein the lithium amount is a mass ratio of lithium to the lithium nickel composite oxide determined by adding the lithium nickel composite oxide to solution to make a slurry, after which an amount of alkali content in the slurry is found by titration with acid using pH of the slurry as an index, and then performing lithium conversion from the amount of alkali content.

7 . The positive electrode active material for a nonaqueous electrolyte secondary battery according to claim 6 , wherein the acid used for the titration is at least one selected from a group consisting of hydrochloric acid, sulfuric acid, nitric acid, and organic acid.

8 . A method for producing a positive electrode active material for a nonaqueous electrolyte secondary battery according to claim 1 , comprising:
(i) a step of preparing a fired powder of the lithium nickel composite oxide by mixing a nickel composite compound selected from among nickel composite hydroxide, nickel oxy composite hydroxide, and nickel composite oxide, and having nickel as a main component and at least one kind of element selected from transition metal elements other than nickel, group 2 elements, and group 13 elements as a subcomponent, with a lithium compound, and then firing a mixture thereof in an oxygen atmosphere under firing conditions where a maximum temperature is in a range of 650° C. to 850° C., the lithium nickel composite oxide being represented by composition formula (3):
Li b Ni 1−a M1 a O 2 ,
where M1 represents at least one kind of element selected from transition metal elements other than Ni, group 2 elements, and group 13 elements, 0.01≤a≤0.5, and 0.95≤b≤1.13; and (ii) a step of preparing a powder of the lithium nickel composite oxide by performing a water washing process of the fired powder with spraying the fired powder with water in a temperature range of 10° C. to 40° C., until an electric conductivity of filtrate is in a range of 30 S/cm to 60 mS/cm, to make a fired powder slurry, then performing filtration of the fired powder slurry until a moisture content of adhered water remaining on a particle surface of the fired powder after washing is 10% by mass or less, to obtain a filtered powder, and performing drying of the filtered powder.

9 . The method for producing a positive electrode active material for a nonaqueous electrolyte secondary battery according to claim 8 , wherein, in the step (ii), the fired powder slurry has a slurry concentration in a range of 500 g/L to 3000 g/L.

10 . The positive electrode active for a nonaqueous electrolyte secondary battery according to claim 8 , wherein, in the step (ii), drying of the filtered powder is performed in a gas atmosphere that does not include a compound component including carbon or a vacuum atmosphere.

11 . The method for producing a positive electrode active material for a nonaqueous electrolyte secondary battery according to claim 8 , wherein the nickel composite hydroxide is prepared by dripping an aqueous solution including a nickel compound as a main component and a compound of at least one kind of element selected from transition metal elements other than nickel, group 2 elements, and group 13 elements as a subcomponent, and an aqueous solution including an ammonium ion supplier into a heated reaction tank; and at that time, dripping an aqueous solution of an alkali metal hydroxide in an amount capable of maintaining an alkalinity of a reaction solution.

12 . The method for producing a positive electrode active material for a nonaqueous electrolyte secondary battery according to claim 8 , wherein the nickel oxy composite hydroxide is prepared by dripping an aqueous solution including a nickel compound as a main component and a compound of at least one kind of element selected from transition metal elements other than nickel, group 2 elements, and group 13 elements as a subcomponent, and an aqueous solution including an ammonium ion supplier into a heated reaction tank; and at that time, dripping an aqueous solution of an alkali metal hydroxide in an amount capable of maintaining an alkalinity of a reaction solution, and continuing to further add an oxidizing agent.

13 . The method for producing a positive electrode active material for a nonaqueous electrolyte secondary battery according to claim 8 , wherein the nickel composite oxide is obtained by roasting the nickel composite hydroxide or the nickel oxy composite hydroxide.

14 . The method for producing a positive electrode active material for a nonaqueous electrolyte secondary battery according to claim 8 , wherein at least one kind selected from a group including lithium hydroxide, lithium oxyhydroxide, lithium oxide, lithium carbonate, lithium nitrate, and lithium halide is used as the lithium compound.

15 . The method for producing a positive electrode active material for a nonaqueous electrolyte secondary battery according to claim 8 , wherein in the step (i), a mixing ratio of the nickel composite compound and the lithium compound is adjusted so that a molar ratio of a molar amount of lithium in the lithium compound with respect to a total molar amount of nickel, transition metal element other than nickel, group 2 element, and group 13 element in the nickel composite compound is in a range of 0.95 to 1.13.

16 . A nonaqueous electrolyte secondary battery comprising a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and a nonaqueous electrolyte, wherein the positive electrode active material according to claim 1 is used as a positive electrode material of the positive electrode.

Assignees

• Sumitomo Metal Mining Co

Inventors

• Nakayama Tomoko
• Yokoyama Jun
• Komukai Tetsufumi

Classifications

• H01M2004/027

  Negative electrodes · CPC title

• H01M4/133

  Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx · CPC title

• H01M4/525 Primary

  of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy · CPC title

• H01M2004/028

  Positive electrodes · CPC title

• H01M4/505

  of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy · CPC title