Nickel composite hydroxide and manufacturing method thereof, cathode active material for nonaqueos-electrolyte secondary battery and manufacturing method thereof, and nonaqueous-electrolyte secondary battery
Provided are a cathode active material having a suitable particle size and high uniformity, and a nickel composite hydroxide as a precursor of the cathode active material. When obtaining nickel composite hydroxide by a crystallization reaction, nucleation is performed by controlling a nucleation aqueous solution that includes a metal compound, which includes nickel, and an ammonium ion donor so that the pH value at a standard solution temperature of 25° C. becomes 12.0 to 14.0, after which, particles are grown by controlling a particle growth aqueous solution that includes the formed nuclei so that the pH value at a standard solution temperature of 25° C. becomes 10.5 to 12.0, and so that the pH value is lower than the pH value during nucleation. The crystallization reaction is performed in a non-oxidizing atmosphere at least in a range after the processing time exceeds at least 40% of the total time of the particle growth process from the start of the particle growth process where the oxygen concentration is 1 volume % or less, and with controlling an agitation power requirement per unit volume into a range of 0.5 kW/m 3 to 4 kW/m 3 at least during the nucleation process.
1. A cathode active material for a nonaqueous-electrolyte secondary battery that is essentially composed of a lithium nickel composite oxide that is expressed by the general expression:
L 1+u Ni x Mn y Co z M t O 2 (−0.05≤u≤0.50, x+y+z+t=1, 0.3≤x, 0≤y≤0.55, 0≤z≤0.4, 0≤t≤0.1, and M is one or more kind of additional element that is selected from among Al, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta and W), and has a hexagonal crystal structure;
the lithium nickel composite oxide composed of substantially spherical secondary particles that are formed of sintered primary particles that clump together,
wherein
an average secondary particle size thereof is greater than 8 μm and less than or equal to 16 μm, and a value [(d90-d10)/average particle size], which is an index that indicates the extent of the particle size distribution, being 0.60 or less,
the tap density is 1.8 g/cm 3 or more, and
wherein the nickel content and the manganese content of the lithium nickel composite oxide are regulated in the general expression so as to be 0.3≤x≤0.7 and 0.1≤y≤0.55, respectively,
the secondary particles respectively have a hollow structure which is composed of an outer-shell section that is formed by the sintered primary particles that clump together, and a hollow center section that exists inside the outer-shell section, and
the specific surface area is 0.8 m 2 /g or greater and 2.0 m 2 /g or less.
2. The cathode active material for a nonaqueous-electrolyte secondary battery according to claim 1 , wherein the ratio of the thickness of the outer-shell section with respect to the particle size of the lithium nickel composite oxide is 5% to 45%.
3. A nonaqueous-electrolyte secondary battery having a cathode thereof being formed using the cathode active material for a nonaqueous-electrolyte secondary battery according to claim 1 .