Patent ID: 7309546

Claim:
A positive active material for a rechargeable lithium battery comprising: a lithiated intercalation compound comprising at least one bare compound represented by the following formulas (1) to (12): Li x Mn 1-y M y A 2 (1) Li x Mn 1-y M y O 2-z X z (2) Li x Mn 2 O 4-z X z (3) Li x Co 1-y M y A 2 (4) Li x Co 1-y M y O 2-z X z (5) Li x Ni 1-y M y A 2 (6) Li x Ni 1-y M y O 2-z X z (7) Li x Ni 1-y Co y O 2-z X z (8) Li x Ni 1-y-z Co y M z A α (9) Li x Ni 1-y-z Co y M z O 2-α X α (10) Li x Ni 1-y-z Mn y M z A α (11) Li x Ni 1-y-z Mn y M z O 2-α X α (12) where 0.9≦×1.1; 0≦y≦0.5; 0≦z≦0.5; 0≦α≦2; M is selected from the group consisting of Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, and rare earth elements; A is selected from the group consisting of O, F, S, and P; and X is F, S, or P; and an additive compound comprising one or more compounds represented by the formula M′Mn 2-x Ni x O 4 , where M′ is Li or Na, and x ranges from 0.1 to 0.9, wherein the bare compound is coated with a metal oxide shell and the additive compound has a charging voltage of 4.0 to 4.6V when 5-50% of the M′ is released during charging, and wherein the mixing weight ratio of the lithiated intercalation compound and the additive compound ranges from 99.99 to 70: 0.01 to 30.