Aluminum-coated nickel cobalt containing composite hydroxide and method for manufacturing same, cathode active material for non-aqueous electrolyte secondary battery and method for manufacturing same, and non-aqueous electrolyte secondary battery

A method for manufacturing a cathode active material for a non-aqueous electrolyte secondary battery that includes a lithium nickel cobalt composite oxide having a layered structure that is expressed by a general formula:

• LiuNi1-x-y-zCoxAlyMgzO2 (where 1.00≤u≤1.04, 0.05≤x≤0.20, 0.01≤y≤0.06, and 0.01≤z≤0.03) and that includes secondary particles having a solid structure that are formed by an aggregate of plural primary particles,
• the average particle size of the secondary particles of the cathode active material being within the range 4 μm to 7 μm or less, the tap density of the cathode material being 2.0 g/mL or greater and 2.3 g/mL or less, and the specific surface area of the cathode active material being within the range 0.7 m2/g to 1.0 m2/g,
• wherein the primary particles of the cathode active material have a rectangular parallelepiped shape, and the average particle size of the primary particles of the cathode active material is within the range 0.05 μm to 0.5 μm,
• the average particle size of the primary particles of the cathode active material is the crystallite diameter which is found from the Scherer equation using results from x-ray diffraction measurements;
• and
• the lithium nickel cobalt composite oxide having a crystal structure in which cobalt, magnesium and aluminum are uniformly dissolved in a matrix composed of LiNiO2,
• the method comprising:
• a mixing step for obtaining a lithium mixture by mixing an aluminum-coated nickel cobalt composite hydroxide or a roasted material thereof as a precursor with a lithium compound, wherein
• the aluminum-coated nickel cobalt composite hydroxide consists of:
• Ni1-x-y-zCoxAlyMgz(OH)2 (where, 0.05≤x≤0.20, 0.01≤y≤0.06, and 0.01≤z≤0.03), and includes secondary particles, wherein
• the secondary particles of the precursor have a structure in which a main part has a solid structure that is formed by an aggregate of plural primary particles and in which nickel, cobalt, and magnesium are uniformly dispersed, the main part coated by a coating film that includes aluminum or an aluminum compound;
• the average particle size of the secondary particles of the precursor being within the range of 4 μm to 7 μm or less, the tap density of the precursor being 1.5 g/mL or greater, and the specific surface area of the precursor being within the range of 5.5 m2/g to 7.5 m2/g;
• and
• the primary particles of the precursor have a rectangular parallelepiped shape, and the average particle size of the primary particles is within the range of 0.01 μm to 0.1 μm;
• the average particle size of the primary particles of the precursor is the crystallite diameter which is found from the Scherer equation using results from x-ray diffraction measurements;
• and
• a calcination step for obtaining a lithium nickel cobalt containing composite oxide by calcining the lithium mixture in an oxidizing atmosphere in which the oxygen concentration is 98% by volume or greater.