| abstract |
[PROBLEMS] To provide an inexpensive and high-performance positive electrode active material for a lithium secondary battery with improved safety and a secondary battery using the same. A has a layered crystal structure, and its composition formula Li a Ni 1-xyz M x Al y Y z O 2, except 0.95 0 ≦ a ≦ 1.100, 0.000 ≦ x ≦ 0.300 (M Is a transition metal other than nickel) 0.001 ≦ y ≦ 0.05 0, 0.001 ≦ z ≦ 0.05, 0.005 ≦ y + z A positive electrode active material for a lithium secondary battery comprising a composite oxide of lithium and a transition metal represented by ≦ 0.100, and a lithium secondary battery using the same as a positive electrode active material. The specific surface area of the active material is preferably in the range of 0.1 to 1.0 m 2 / g, and the sulfur content is preferably 0.1% by weight or less. |