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:
Li 1+u Ni x Mn y Co z M t O 2 (x+y+z+t=1, 0.3≤x, 0≤y≤0.55, 0≤z≤0.4, 0≤t≤0.1, wherein 0.7≤x, −0.05≤u≤0.50, or 0.3≤x≤0.7, 0.10≤u≤0.50, and M as an additive element is selected from one or more of among Al, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta and W, and has a hexagonal crystal structure with a layered structure;
the lithium nickel composite oxide composed of substantially spherical secondary particles that are formed of sintered primary particles that clump together, wherein Li, Ni, Mn, and Co are uniformly dispersed throughout the primary particles,
wherein
an average 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 2.0 g/cm 3 or more, and
wherein the secondary particles respectively have a solid structure that is dense from the outside to the inside by the sintered primary particles that clump together, and the specific surface area is preferably 0.2 m 2 /g or greater and 1.5 m 2 /g or less.
2. 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 .
3. The cathode active material for a nonaqueous-electrolyte secondary battery according to claim 1 , wherein M is uniformly dispersed inside of the secondary particles or coated on its surface.
4. 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 3 .