Positive-electrode active material for non-aqueous electrolyte secondary batteries, production method thereof, and nonaqueous electrolyte secondary battery

Patent metadata

Field	Value
Publication number	US-2019020023-A1
Application number	US-201615771208-A
Country	US
Kind code	A1
Filing date	Oct 27, 2016
Priority date	Oct 28, 2015
Publication date	Jan 17, 2019
Grant date	—

Abstract

A positive electrode active material for nonaqueous electrolyte secondary batteries has a high charge/discharge capacity and produces high output, as well as has high filling ability. The positive electrode active material includes lithium-nickel composite oxide particles are formed by agglomeration of multiple primary particles, include pores, and have a layered crystal structure. The lithium-nickel composite oxide particles have an average particle size of 15 μm or more and 30 μm or less. The percentage of an area of the pores measured by a cross-sectional observation of the lithium-nickel composite oxide particles with respect to a cross-sectional area of the lithium-nickel composite oxide particles is 1.0% or more and 5.0% or less. A lithium-tungsten compound containing tungsten and lithium is present on the surface of and inside the secondary particles. The lithium-tungsten compound is present on at least part of the surface of the primary particles.

First claim

1 . A positive electrode active material for nonaqueous electrolyte secondary batteries, comprising
lithium-nickel composite oxide particles that consist of secondary particles, the secondary particles being each formed by agglomeration of a plurality of primary particles and including pores, have a composition represented by Li z Ni 1-x-y Co x M y W a O 2+α where 0≤x≤0.35; 0≤y≤0.35; 0.95≤z≤1.30; 0<a≤0.03; 0≤α≤0.15; and M is at least one element selected from Mg, Al, Ca, Ti, V, Cr, Mn, Nb, Zr, and Mo, and have a layered crystal structure, wherein the lithium-nickel composite oxide particles have an average particle size of 15 μm or more and 30 μm or less, the percentage of an area of the pores measured by a cross-sectional observation of the lithium-nickel composite oxide particles with respect to a cross-sectional area of the lithium-nickel composite oxide particles is 1.0% or more and 5.0% or less, a lithium-tungsten compound containing tungsten and lithium is present on the surface of and inside the secondary particles, the lithium-tungsten compound is present on at least part of the surface of the primary particles, and the amount of lithium contained in a lithium compound other than the lithium-tungsten compound present on the surface of the primary particles with respect to the total amount of the lithium-nickel composite oxide particles is 0.05% by mass or less.

2 . The positive electrode active material for nonaqueous electrolyte secondary batteries of claim 1 , wherein the sulfate group content of the positive electrode active material for nonaqueous electrolyte secondary batteries is 0.15% by mass or less.

3 . The positive electrode active material for nonaqueous electrolyte secondary batteries of claim 1 , wherein the tap density of the positive electrode active material for nonaqueous electrolyte secondary batteries is 2.5 g/cm 3 or more.

4 . The positive electrode active material for nonaqueous electrolyte secondary batteries of claim 1 , wherein the lithium-tungsten compound contains 0.05% by atom or more and 3.0% by atom or less of tungsten with respect to the sum of the atomic numbers of Ni, Co, and M contained in the lithium-nickel composite oxide particles.

5 . The positive electrode active material for nonaqueous electrolyte secondary batteries of claim 1 , wherein the lithium-tungsten compound contains lithium tungstate.

6 . The positive electrode active material for nonaqueous electrolyte secondary batteries of claim 1 , wherein the lithium-tungsten compound is present on at least part of the surface of the primary particles as fine particles having particle sizes of 1 nm or more and 500 nm or less.

7 . The positive electrode active material for nonaqueous electrolyte secondary batteries of claim 1 , wherein the lithium-tungsten compound is present on at least part of the surface of the primary particles as coatings having thicknesses of 1 nm or more and 200 nm or less.

8 . The positive electrode active material for nonaqueous electrolyte secondary batteries of claim 1 , wherein the lithium-tungsten compound is present on at least part of the surface of the primary particles as both particles having particle sizes of 1 nm or more and 500 nm or less and coatings having thicknesses of 1 nm or more and 200 nm or less.

9 . A method for producing a positive electrode active material for nonaqueous electrolyte secondary batteries, the positive electrode active material comprising lithium-nickel composite oxide particles that consist of secondary particles, the secondary particles being each formed by agglomeration of a plurality of primary particles and including pores, have a composition represented by Li z Ni 1-x-y Co x M y W a O 2+α where 0≤x≤0.35; 0≤y≤0.35; 0.95≤z≤1.30; 0<a≤0.03; 0≤α≤0.15; and M is at least one element selected from Mg, Al, Ca, Ti, V, Cr, Mn, Nb, Zr, and Mo, and have a layered crystal structure, the method comprising:
mixing a nickel composite hydroxide containing nickel and optionally cobalt and M, a nickel-oxy hydroxide obtained from the nickel composite hydroxide, a nickel composite oxide, or a mixture thereof, and a lithium compound so that the molar ratio of lithium in the lithium compound to the sum of the atomic numbers of Ni, Co, and M in the nickel composite hydroxide becomes 0.95 or more and 1.30 or less, to obtain a lithium mixture;
firing the lithium mixture at 700° C. or more and 900° C. or less in an oxidizing atmosphere to obtain lithium-nickel composite oxide particles;
mixing the lithium-nickel composite oxide particles obtained after the firing with water to form a lithium-nickel composite oxide slurry, cleaning the lithium-nickel composite oxide particles by stirring the slurry, and then solid-liquid separating the resulting slurry to obtain a cleaned cake comprising the lithium-nickel composite oxide particles;
mixing the cleaned cake and a tungsten compound that is substantially free of lithium to obtain a tungsten mixture; performing a first heat-treatment involving heat-treating the tungsten mixture to dissolve the tungsten compound and thus to form lithium-nickel composite oxide particles where tungsten is dispersed on the surface of the primary particles and on the surface of and inside the secondary particles; and after the first heat-treatment, performing a second heat-treatment involving performing a heat-treatment at a higher temperature than in the first heat-treatment to obtain lithium-nickel composite oxide particles whose porosity is 1.0% or more and 5.0% or less and where a lithium-tungsten compound is formed on the surface of the primary particles and on the surface of and inside the secondary particles.

10 . The method for producing the positive electrode active material for nonaqueous electrolyte secondary batteries of claim 9 , wherein the nickel composite hydroxide is obtained using a method comprising:
charging an aqueous solution containing nickel and optionally cobalt and M and an aqueous solution containing an ammonium ion donor into a reaction bath whose temperature is controlled to 40° C. or more and 60° C. or less to obtain a reaction solution and adding an aqueous solution of sodium hydroxide to the reaction solution so that the pH of the reaction solution is controlled to 12.0 or more and 14.0 or less on a 25° C. solution temperature basis and the ammonia concentration is controlled to 5 g/L or more and 20 g/L or less, to obtain a nickel composite hydroxide slurry; solid-liquid separating the nickel composite hydroxide slurry to obtain a nickel composite hydroxide cake; and cleaning the nickel composite hydroxide cake with water, or cleaning the nickel composite hydroxide cake with an aqueous solution of sodium hydroxide and then cleaning the resulting nickel composite hydroxide cake with water, and then drying the resulting nickel composite hydroxide cake.

11 . The method for producing the positive electrode active material for nonaqueous electrolyte secondary batteries of claim 10 , wherein the nickel composite hydroxide cake is cleaned with 3.5% by mass or less of an aqueous solution of sodium hydroxide.

12 . The method for producing the positive electrode active material for nonaqueous electrolyte secondary batteries of claim 9 , wherein the sulfate group content of the nickel composite hydroxide is 0.5% by mass or more and 2.0% by mass or less.

13 . The method for producing the positive electrode active material for nonaqueous electrolyte secondary batteries of claim 9 , wherein
the lithium mixture is obtained by mixing a nickel composite oxide obtained by oxidizing-roasting the nickel composite hydroxide at a temperature of 500° C. or more and 750° C. or less, a

Assignees

• Sumitomo Metal Mining Co

Inventors

• Yokoyama Jun
• Furuichi Yuki
• Komukai Tetsufumi

Classifications

• 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

• H01M4/0471

  involving thermal treatment, e.g. firing, sintering, backing particulate active material, thermal decomposition, pyrolysis · CPC title

• H01M4/366

  as layered products · CPC title

• H01M2004/021

  Physical characteristics, e.g. porosity, surface area · CPC title

• C01P2004/50

  Agglomerated particles · CPC title