Nickel complex hydroxide particles and nonaqueous electrolyte secondary battery
Disclosed are: nickel complex hydroxide particles that have small and uniform particle diameters; and a method by which the nickel complex hydroxide particles can be produced. Specifically disclosed is a method for producing a nickel complex hydroxide by a crystallization reaction, which comprises: a nucleation step in which nucleation is carried out, while controlling an aqueous solution for nucleation containing an ammonium ion supplying material and a metal compound that contains nickel to have a pH of 12.0-13.4 at a liquid temperature of 25° C.; and a particle growth step in which nuclei are grown, while controlling an aqueous solution for particle growth containing the nuclei, which have been formed in the nucleation step, to have a pH of 10.5-12.0 at a liquid temperature of 25° C. In this connection, the pH in the particle growth step is controlled to be less than the pH in the nucleation step.
1. A cathode active material for a nonaqueous electrolyte secondary battery comprising a lithium-nickel composite oxide comprising a composite oxide containing lithium, represented by the general formula (II):
Li t Ni 1-x-y Co x M y O 2 (II)
wherein 0.95≦t≦1.15, 0≦x≦0.2, 0≦y≦0.15, x+y<0.3, and M is at least one element selected from the group consisting of Mg, Al, Ca, Ti, V, Cr, Mn, Zr, Nb, Mo and W,
wherein said particles have an average particle diameter of 2 to 8 μm, and an index showing the extent of particle size distribution represented by [(d90−d10)/average particle diameter] is 0.58 or less.
2. The cathode active material for a nonaqueous electrolyte secondary battery according to claim 1 , wherein said cathode active material is produced by a process, wherein
said cathode active material comprises a lithium-nickel composite oxide represented by the general formula (II):
Li t Ni 1-x-y Co x M y O 2 (II)
wherein 0.95≦t≦1.15, 0≦x≦0.2, 0≦y≦0.15, x+y<0.3, and M is at least one element selected from the group consisting of Mg, Al, Ca, Ti, V, Cr, Mn, Zr, Nb, Mo and W,
said process comprises:
a step for thermally treating the nickel composite hydroxide particles, wherein the nickel composite hydroxide is represented by the general formula (I):
Ni 1-x-y Co x M y (OH) 2+α (I)
wherein 0≦x≦0.2, 0≦y≦0.15, x+y<0.3, 0≦α≦0.5, and M is at least one additive element selected from the group consisting of Mg, Al, Ca, Ti, V, Cr, Mn, Zr, Nb, Mo and W,
said spherical secondary particles are formed by the aggregation of plural platelike primary particles, and have an average particle diameter of 3 to 7 μm; and an index showing the extent of particle size distribution represented by the formula: [(d90−d10)/average particle diameter] is 0.55 or less,
a step for mixing a lithium compound with the particles after said thermal treatment, to give a mixture, and
a step for calcining said mixture formed in the step for mixing at a temperature of 700° C. to 850° C.
3. A nonaqueous electrolyte secondary battery, comprising the cathode active material for a nonaqueous electrolyte secondary battery according to claim 1 .