Positive active material for rechargeable lithium battery and method of preparing same

Abstract

A positive active material for rechargeable lithium batteries includes an active material component processed from a manganese-based compound. The transition metal compound is selected from Li x MnO 2 , Li x MnF 2 , Li x MnS 2 , Li x MnO 2-z F z , Li x MnO 2-z S z , Li x Mn 1-y M y O 2 , Li x Mn 1-y M y F 2 , Li x Mn 1-y M y S 2 , Li x Mn 1-y M y O 2-z F z , Li x Mn 1-y O 2-z S z , Li x Mn 2 O 4 , Li x Mn 2 F 4 , Li x Mn 2 S 4 , Li x Mn 2 O 4-z F z , Li x Mn 2 O 4-z S z , Li x Mn 2-y M y O 4 , Li x Mn 2-y M y F 4 , Li x Mn 2-y M y S 4 , Li x Mn 2-y M y O 4-z F z , or Li x Mn 2-y M y O 4-z S z where 0<x≦1.5, 0.05≦y≦0.3, z≦1.0 and M is selected from Al, Co, Cr, Mg, Fe or La. A metallic oxide is coated on the active material component.

1 . A positive active material for rechargeable lithium batteries, the positive active material comprising: 
 an active material component processed from a manganese-based compound, the manganese-based compound being selected from the group consisting of Li x Mn 1-y M y O 2 , Li x Mn 1-y M y O 2-z F z , Li x Mn 1-y M y O 2-z S z , Li x Mn 2-y M y O 4-z F z , and Li x Mn 2-y M y O 4-z S z , where 0<x<1.5, 0.05≦y≦0.3, 7≦1.0 and M is selected from the group consisting of Al, Co, Cr, Mg, Fe and La; and    a metallic oxide coated on the active material component, the metallic oxide comprising a metal selected from the group consisting of Mg Al wherein the positive active material is formed of metallic oxide coated active material moieties.    
     
     
         2 . The positive active material of  claim 1  wherein the oxide has a thickness range of 1-1000 nm.  
     
     
         3 . The positive active material of  claim 1  wherein the quantity of metal content is a range of 1 to 10 weight percent of the oxide.  
     
     
         4 . A positive electrode for rechargeable lithium batteries, the positive electrode comprising: 
 a plurality of active material particles processed from a manganese-based compound, the manganese-based compound being selected from the group consisting of Li x MnO 2 , Li x Mn 1-y M y O 2 , Li x Mn 1-y M y O 2-z F z , Li x Mn 1-y M y O 2-z S z , Li x Mn 2 O 4 , Li x Mn 2-y M y O 4 , Li x Mn 2-y M y O 4-z F z , and Li x Mn 2-y M y O 4-z S z , where 0<x<1.5, 0.05≦y≦0.3, z≦1.0 and M is selected from the group consisting of Al, Co, Cr, Mg, Fe and La, and a metallic oxide coated on each of the active material particles, the metallic oxide comprising a metal selected from the group consisting of Mg and Al;    wherein the positive electrode comprises the active material particles coated with the metallic oxide, and wherein the positive electrode is formed after the active material particles are coated with the metallic oxide.    
     
     
         5 . The positive electrode of  claim 4 , wherein the oxide has a thickness range of 1 to 1000 nanometers.  
     
     
         6 . The positive electrode of  claim 4 , wherein the quantity of metal content is in a range of 1 to 10 weight percent of the oxide.