Nickel-cobalt-manganese complex hydroxide particles and method for producing same, positive electrode active material for nonaqueous electrolyte secondary battery and method for producing same, and nonaqueous electrolyte secondary battery
An object of the present invention is to provide nickel cobalt manganese composite hydroxide particles having a small particle diameter and a uniform particle size distribution, and a method for producing the same. [Solution] A method for producing a nickel cobalt manganese composite hydroxide by a crystallization reaction is provided. The method includes: a nucleation step of performing nucleation by controlling a pH of an aqueous solution for nucleation including metal compounds containing nickel, cobalt and manganese, and an ammonium ion donor to 12.0 to 14.0 in terms of the pH as measured at a liquid temperature of 25° C. as a standard; and a particle growth step of growing nuclei by controlling a pH of an aqueous solution for particle growth containing nuclei formed in the nucleation step to 10.5 to 12.0 in terms of the pH as measured at a liquid temperature of 25° C. as a standard.
1. A cathode active material for a nonaqueous electrolyte secondary battery represented by a general formula: Li 1+u Ni x Co y Mn z M t O 2 , where −0.05≤u≤0.20, x+y+z+t=1, 0.3≤x≤0.7, 0.1≤y≤0.4, 0.1≤z≤0.4, 0≤t≤0.02, and M is at least one additional element selected from the group consisting of Ti, V, Cr, Al, Mg, Zr, Nb, Mo, Hf, Ta and W,
the cathode active material including a lithium nickel cobalt manganese composite oxide of a composite oxide containing lithium with a layer structure belonged in hexagonal crystal system, and
having an average particle diameter of 2 to 8 μm and a value represented by an expression of: [(d90−d10)/average particle diameter] as a marker indicating spreading of a particle size distribution of 0.60 or less.
2. The cathode active material for a nonaqueous electrolyte secondary battery according to claim 1 , wherein
the cathode active material for a nonaqueous electrolyte secondary battery is produced by a production method comprising:
a step of subjecting a nickel cobalt manganese composite hydroxide particles represented by a general formula: Ni x Co y Mn z M t (OH) 2+a , where 0.3≤x≤0.7, 0.1≤y≤0.4,
0.1≤z≤0.5, 0≤t≤0.02, x+y+z+t=1, 0≤a≤0.5, and M is at least one additional element selected from the group consisting of Ti, V, Cr, Al, Mg, Zr, Nb, Mo, Hf, Ta and W,
the nickel cobalt manganese composite hydroxide particles being spherical secondary particles formed by aggregation in a random direction of a plurality of platelike primary particles having an average thickness of 10 nm to 300 nm and an average length of 100 nm to 3000 nm, to a heat treatment;
a mixing step of forming a mixture by mixing a lithium compound with particles after the heat treatment, and adjusting a ratio of a sum of the number of atoms of metals other than lithium to the number of atoms of lithium included in the mixture to 1:0.95 to 1.20; and
a firing step of firing the mixture formed in the mixing step at a temperature of 800° C. to 1000° C.
3. A nonaqueous electrolyte secondary battery having a positive electrode formed with the cathode active material for a nonaqueous electrolyte secondary battery according to claim 1 .