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

Abstract

A positive active material for a rechargeable lithium battery is provided. The positive active material includes at least one compound selected from the group consisting of lithiated compounds, a metal oxide layer formed on a surface of the compound and metal oxide masses adhered on the metal oxide layer. The positive active material is produced by coating a compound with a metal alkoxide solution, an organic solution of a metal salt or an aqueous solution of a metal salt and heat-treating the coated compound. The compound is selected from the group consisting of lithiated compounds. Thereafter, the heat-treated compound is slow-cooled to 100 to 500° C. and the cooled compound is quenched to room temperature.

1. A positive active material for a rechargeable lithium battery comprising:
 at least one compound selected from the group consisting of lithiated compounds represented by formulas 1 to 9;
   Li x Mn 1-y M′ y A 2    (1)
 
   Li x Mn 1-y M′ y O 2-z A z    (2)
 
   Li x Mn 2 O 4-z A z    (3)
 
   Li x Mn 2-y M′ y A 4    (4)
 
   Li x B 1-y M″ y A 2    (5)
 
   Li x BO 2-z A z    (6)
 
   Li x Ni 1-y-z Co y O 2-z A z    (7)
 
   Li x Ni 1-y-z Co y M″ z A 2α   (8)
 
   Li x Ni 1-y-z Mn y M′ z A α   (9)
 
 
 where 0.95≦x≦1.1, 0≦y≦0.5, 0≦z≦0.5; 0≦α≦2; 
 M′ is at least one element selected from the group consisting of Al, Cr, Co, Ni, Fe, Mg, Sr, V, 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. Cf, Es, Fm, Md, No and Lr; 
 M″ is at least one element selected from the group consisting of Al, Cr, Mn, Fe, Mg, Sr, V, 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; 
 A is selected from the group consisting of O, F, S and P; and 
 B is selected from the group consisting of Ni and Co; 
 a metal oxide layer formed on a surface of the compound; and 
 a plurality of metal oxide masses adhered on the metal oxide layer. 
 
     
     
       2. The positive active material for a rechargeable lithium battery of  claim 1  wherein the metal of the metal oxide layer and metal oxide masses is selected from the group consisting of Mg, Al, Co, K, Na, Ca, Si, Ti, V, Ga, Ge, Sn, B and As. 
     
     
       3. The positive active material for a rechargeable lithium battery of  claim 1  wherein a thickness of the metal oxide layer is 1 to 100 nm. 
     
     
       4. A method of preparing a positive active material for a rechargeable lithium battery according to  claim 1 , comprising the steps of:
 coating at least one compound with a metal alkoxide solution, an organic solution of a metal salt or an aqueous solution of a metal salt, the compound being selected from the group consisting of lithiated compounds represented by formulas 1 to 9;
   Li x Mn 1-y M′ y A 2    (1)
 
   Li x Mn 1-y M′ y O 2-z A z    (2)
 
   Li x Mn 2 O 4-z A z    (3)
 
   Li x Mn 2-y M′ y A 4    (4)
 
   Li x B 1-y M″ y A 2    (5)
 
   Li x BO 2-z A z    (6)
 
   Li x Ni 1-y-z Co y O 2-z A z    (7)
 
   Li x Ni 1-y-z Co y M″ z A 2α   (8)
 
   Li x Ni 1-y-z Mn y M′ z A α   (9)
 
 
 where 0.95≦x≦1.1, 0≦y≦0.5, 0≦z≦0.5; 0≦α≦2; 
 M′ is at least one element selected from the group consisting of Al, Cr, Co, Ni, Fe, Mg, Sr, V, 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. Cf, Es, Fm, Md, No and Lr; 
 M″ is at least one element selected from the group consisting of Al, Cr, Mn, Fe, Mg, Sr, V, 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; 
 A is selected from the group consisting of O, F, S and P; and 
 B is selected from the group consisting of Ni and Co; 
 heat-retreatheat-treating the coated-compound; 
 slow-cooling the heat-treated compound to 100 to 500° C; and 
 quenching the cooled compound to room temperature. 
 
     
     
       5. The method of  claim 4  wherein the compound is coated with a metal alkoxide solution containing a metal selected from the group consisting of Mg, Al, Co, K, Na, Ca, Si, Ti, V, Ga, Ge, Sn, B and As. 
     
     
       6. The method of  claim 4  wherein the metal alkoxide solution and the metal aqueous solution have a concentration of 1 to 20%. 
     
     
       7. The method of  claim 4  wherein the heat-treating step is performed at 200 to 1000° C. for 1 to 20 hours. 
     
     
       8. The method of  claim 4  wherein the quenching step is performed at a quenching rate of more than or equal to 0.5° C./min. 
     
     
       9. A positive active material for a rechargeable lithium battery comprising:
 at least one compound selected from the group consisting of lithiated compounds represented by formulas 1 to 9;
   Li x Mn 1-y M′ y A 2    (1)
 
   Li x Mn 1-y M′ y O 2-z A z    (2)
 
   Li x Mn 2 O 4-z A z    (3)
 
   Li x Mn 2-y M′ y A 4    (4)
 
   Li x B 1-y M″ y A 2    (5)
 
   Li x BO 2-z A z    (6)
 
   Li x Ni 1-y-z Co y O 2-z A z    (7)
 
   Li x Ni 1-y-z Co y M″ z A 2α   (8)
 
   Li x Ni 1-y-z Mn y M′ z A α   (9)
 
 
 where 0.95≦x≦1.1, 0≦y≦0.5, 0≦z≦0.5; 0≦α≦2; 
 M′ is Ni; 
 M″ is at least one element selected from the group consisting of Al, Cr, Mn, Fe, Mg, Sr, V, 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; 
 A is selected from the group consisting of O, F, S and P; and 
 B is selected from the group consisting of Ni and Co; 
 a metal oxide layer formed on a surface of the compound; and 
 a plurality of metal oxide masses adhered on the metal oxide layer. 
 
     
     
       10. The positive active material for a rechargeable lithium battery of  claim 9  wherein the metal of the metal oxide layer and metal oxide masses is selected from the group consisting of Mg, Al, Co, K, Na, Ca, Si, Ti, V, Ga, Ge, Sn, B and As. 
     
     
       11. The positive active material for a rechargeable lithium battery of  claim 9  wherein a thickness of the metal oxide layer is 1 to 100 nm. 
     
     
       12. A method of preparing a positive active material for a rechargeable lithium battery according to  claim 9 , comprising the steps of:
 coating at least one compound with a metal alkoxide solution, an organic solution of a metal salt or an aqueous solution of a metal salt, the compound being selected from the group consisting of lithiated compounds represented by formulas 1 to 9;
   Li x Mn 1-y M′ y A 2    (1)
 
   Li x Mn 1-y M′ y O 2-z A z    (2)
 
   Li x Mn 2 O 4-z A z    (3)
 
   Li x Mn 2-y M′ y A 4    (4)
 
   Li x B 1-y M″ y A 2    (5)
 
   Li x BO 2-z A z    (6)
 
   Li x Ni 1-y-z Co y O 2-z A z    (7)
 
   Li x Ni 1-y-z Co y M″ z A 2α   (8)
 
   Li x Ni 1-y-z Mn y M′ z A α   (9)
 
 
 where 0.95≦x≦1.1, 0≦y≦0.5, 0≦z≦0.5; 0≦α≦2; 
 M′ is Ni; 
 M″ is at least one element selected from the group consisting of Al, Cr, Mn, Fe, Mg, Sr, V, 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; 
 A is selected from the group consisting of O, F, S and P; and 
 B is selected from the group consisting of Ni and Co; 
 heat-treating the coated compound; 
 slow-cooling the heat-treated compound to 100 to 500° C.; and 
 quenching the cooled compound to room temperature. 
 
     
     
       13. The method of  claim 12  wherein the compound is coated with a metal alkoxide solution containing a metal selected from the group consisting of Mg, Al, Co, K, Na, Ca, Si, Ti, V, Ga, Ge, Sn, B and As. 
     
     
       14. The method of  claim 12  wherein the metal alkoxide solution and the metal aqueous solution have a concentration of 1 to 20%. 
     
     
       15. The method of  claim 12  wherein the heat-treating step is performed at 200 to 1000° C. for 1 to 20 hours. 
     
     
       16. The method of  claim 12  wherein the quenching step is performed at a quenching rate of more than or equal to 0.5° C./min.