Patent ID: 8778536

Claim:
A lithium manganese oxide positive active material for a lithium ion secondary battery, the positive active material comprising: a spinel lithium manganese oxide of three or more types of particles having different sizes mixed therein, wherein first spinel lithium manganese oxide particles have an average diameter of 5 μm or greater, second spinel lithium manganese oxide particles have an average diameter of 1 μm or less, third spinel lithium manganese oxide particles have an average diameter of 200 nm or less, the average diameter of the second spinel lithium manganese oxide particles is greater than that of the third spinel lithium manganese oxide particles, a ratio of the number of second spinel lithium manganese oxide particles to the number of third spinel lithium manganese oxide particles is in a range between 1 and 4, the first spinel lithium manganese oxide particles are shaped of spheres, and the third spinel lithium manganese oxide particles are shaped of rods.