Patent ID: 7935444

Claim:
A cathode active material for a lithium secondary battery, comprising a lithium transition metal oxide with a layered crystalline structure in which the transition metal comprises a transition metal mixture of Ni, Mn and Co, an average oxidation number of all transition metals other than lithium is more than +3, and specific conditions represented by the following Formulae (1) and (2) are satisfied: 1.1 <m (Ni)/ m (Mn)<1.5 (1) 0.4 <m (Ni 2+ )/ m (Mn 4+ )<1 (2) wherein m(Ni)/m(Mn) is a molar ratio of nickel to manganese and m(Ni 2+ )/m(Mn 4+ ) is a molar ratio of Ni 2+ to Mn 4+ .