Non-aqueous electrolyte secondary battery

1. A non-aqueous electrolyte secondary battery comprising:

a positive electrode including a positive electrode active material;

a negative electrode including a negative electrode active material;

a separator interposed between said positive electrode and said negative electrode; and

a non-aqueous electrolyte,

wherein said positive electrode active material comprises secondary particles, each comprising an aggregate of primary particles, said primary particles comprising a transition metal-containing composite oxide capable of intercalating and deintercalating lithium ions, and

wherein a value (V Pr ) defined by the formula:

V Pr =(1−C/D)/(A 2 ×B 3 ), is not less than 0.0005 and not greater than 0.04,

where an average particle size of said primary particles is A μm,

an average particle size of said positive electrode active material is B μm,

a tap density of said positive electrode active material is C g/ml, and

a true density of said positive electrode active material is D g/ml,

provided that C is from 2.4 to 2.6,

wherein, said composite oxide is represented by the formula: Li x Ni 1-(y+z) Co y M z O 2 , where 1.01≦x≦1.05, 0.1≦y≦0.2, and 0.02≦z≦0.1, and said element M represents Al.

2. The non-aqueous electrolyte secondary battery in accordance with claim 1 ,

wherein said average particle size of said primary particles A is from 0.1 to 1.5 μm, and

said average particle size of said positive electrode active material B is from 3 to 15 μm.