| 摘要 |
PURPOSE: Provided is a positive active material for a secondary battery having a significantly high energy density per unit weight. A lithium ion secondary having improved cycle property and capacity maintenance is also provided. CONSTITUTION: The positive active material comprises a spinel lithium manganese composite oxide represented by the formula of Lia(NixMn2-x-q-rQqRr)O4, wherein x is 0.4 to 0.6, q>0, r is 0 or more, x+q+r<2, 0<a<1.2, Q is an element selected from the group consisting of Na, K and Ca, and R is an element selected from the group consisting of Li, Be, B, Mg and Al. The secondary battery comprises a cathode formed of the positive active material(11) and an anode separated from the cathode by a separator(15). |
