US Patent 7927506 Cathode active material and lithium battery using the same

Cathode active materials including lithium composite metal oxides having layered-spine composite structures are provided. The lithium metal oxide may be represented by the formula xLi2MO3-yLiMeO2-zLi1+dM′2−dO4, in which 0≦d≦0.33, 0<x<1, 0<y<1, 0<z<1 and x+y+z=1. In the formula M is selected from Mn, Ti, Zn, and combinations thereof. Me is selected from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Al, Mg, Zr, B and combinations thereof. M′ is selected from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Al, Mg, Zr, B, and combinations thereof. The cathode active materials have layered-spinel composite structures in which lithium can be intercalated and deintercalated. Lithium batteries including the cathode active materials show high initial coulombic efficiencies and high capacity retention ratios.