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

Abstract

Disclosed is a positive active material for a rechargeable lithium battery. The positive active material includes at least one compound represented by formulas 1 to 4 and a metal oxide or composite metal oxide layer formed on the compound. Li x Ni 1−y Mn y F 2   (1) Li x Ni 1−y Mn y S 2   (2) Li x Ni 1-−y−2 Mn y M z O 2−a F a   (3) Li x Ni 1−y−z Mn y M z O 2−a S a   (4) (where M is selected from the group consisting of Co, Mg, Fe, Sr, Ti, B, Si, Ga, Al, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Th, Dy, Ho, Er, Tm, Yb, Lu, Ac, Th, Pa, U, Np, Pu, Am, Cm, Bk, Cf, Es, Fm, Md, No and Lr, 0.95≦x≦1.1, 0<y≦0.99, 0≦z≦0.5, and 0≦a≦0.5).

1. A positive active material for a rechargeable lithium battery comprising:
 a plurality of active material particles, each particle of the active material particles comprising at least one compound selected from the group consisting of compounds of the formulas 1 to 4 1 and 2;
   Li x Ni 1−y Mn y F 2   (1)
 
   Li x Ni 1−y Mn y S 2   (2)
 
   Li x Ni 1−y−z Mn y M z O 2−a F a   (3)
 
   Li x Ni 1−y−z Mn y M z O 2−a S a   (4)
 
 
 
       where M is selected from the group consisting of Co, Mg, Fe, Sr, Ti, B, Si, Ga, Al, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Ac, Th, Pa, U, Np, Pu, Am, Cm, Bk, Cf, Es, Fm, Md, No and Lr, and 0.95≦x≦1.1, and 0<y≦0.99, 0≦z≦0.5, and 0≦a≦0.5; and a metal oxide or composite metal oxide layer generally-spherically coating each of the active material particles. 
     
     
       2. The positive active material for a the rechargeable lithium battery of  claim 1  wherein a metal in the metal oxide or composite metal oxide is selected from the group consisting of Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B and As. 
     
     
       3. The positive active material for a the rechargeable lithium battery of  claim 1  wherein a thickness of the layer is 1 to 100 nm. 
     
     
       4. The positive active material for the rechargeable lithium battery of claim 1, wherein the composite metal oxide comprises a metal of a metal alkoxide or a metal salt and a metal of the compound selected from the group consisting of formulas 1 and 2. 
     
     
       5. A positive active material for a rechargeable lithium battery comprising:
 a plurality of active material particles, each of the active material particles comprising at least one compound selected from the group consisting of compounds of formulas 3 and 4;
   Li x Ni 1−y−z Mn y M z O 2−a F a   (3)
 
   Li x Ni 1−y−z Mn y M z O 2−a S a   (4)
 
   
       where M is selected from the group consisting of Co, Mg, Fe, Sr, Ti, B, Si, Ga, Al, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Ac, Th, Pa, U, Np, Pu, Am, Cm, Bk, Cf, Es, Fm, Md, No and Lr, and 0.95≦x≦1.1, 0<y≦0.99, 0≦z≦0.5, and 0≦a≦0.5; and a metal oxide or composite metal oxide layer generally-spherically coating each of the active material particles, and
 wherein a thickness of the metal oxide or composite metal oxide layer is 1 to 100 nm, and 
 wherein the composite metal oxide comprises a metal of a metal alkoxide or a metal salt and a metal of the compound selected from the group consisting of formulas 3 and 4.