Lithium metal oxide, negative electrode active material for lithium secondary battery comprising the same, and method of preparing the same

Abstract

The present invention relates to a lithium metal oxide having a nickel oxide layer formed on a surface thereof, and represented by Formula 1; and the lithium metal oxide can be prepared by a method of preparing a lithium metal oxide having a nickel oxide layer formed on a surface thereof, the method comprising steps of: (1) complexing a nickel precursor onto a surface of a lithium metal oxide; and (2) calcining, through a heat treatment, the lithium metal oxide—the surface of which is complexed with the nickel precursor—obtained in Step (1).

1 . A lithium metal oxide having a nickel oxide layer formed on a surface thereof and represented by Formula 1 below:
   Li x M y O z   [Formula 1]
   in Formula 1 above, M is at least one selected from the group consisting of Ti, Sn, Cu, Pb, Sb, Zn, Fe, In, Al, and Zr; and   x, y, and z are determined according to oxidation number of M.   
     
     
         2 . The lithium metal oxide of  claim 1 , wherein the nickel oxide layer comprises at least one selected from the group consisting of NiO a , NiO, and Ni 2 O 3 , and a satisfies 1<a≦1.5. 
     
     
         3 . The lithium metal oxide of  claim 1 , wherein the nickel oxide is obtained by calcining, through a heat treatment, at least one precursor selected from the group consisting of a nickel nitrate hydrate, a nickel nitrate, a nickel acetate hydrate, a nickel sulfate, and a nickel acetate. 
     
     
         4 . The lithium metal oxide of  claim 1 , wherein the nickel oxide layer has a thickness of 0.1 to 30 nm. 
     
     
         5 . The lithium metal oxide of  claim 1 , wherein the nickel oxide layer is 0.5 to 15 wt % with respect to the total weight of the lithium metal oxide. 
     
     
         6 . The lithium metal oxide of  claim 1 , wherein the lithium metal oxide is at least one selected from the group consisting of Li 4 Ti 5 O 12 , LiTi 2 O 4 , Li 2 TiO 3 , and Li 2 Ti 3 O 7 . 
     
     
         7 . The lithium metal oxide of  claim 1 , wherein the lithium metal oxide is Li 4 Ti 5 O 12 . 
     
     
         8 . A negative electrode active material for a lithium secondary battery, the negative electrode active material comprising the lithium metal oxide of  claim 1 . 
     
     
         9 . A lithium secondary battery comprising the negative electrode active material of  claim 8 . 
     
     
         10 . A method of preparing a lithium metal oxide having a nickel oxide layer formed on a surface thereof, the method comprising steps of:
 (1) complexing a nickel precursor on a surface of a lithium metal oxide; and   (2) calcining, through a heat treatment, the lithium metal oxide—the surface of which is complexed with the nickel precursor—obtained in Step (1).   
     
     
         11 . The method of  claim 10 , wherein the nickel precursor is at least one selected from the group consisting of a nickel nitrate hydrate, a nickel nitrate, a nickel acetate hydrate, a nickel sulfate, and a nickel acetate. 
     
     
         12 . The method of  claim 10 , wherein the nickel precursor is used in an amount of 1 to 20 wt % with respect to the total weight of the lithium metal oxide in Step (1). 
     
     
         13 . The method of  claim 10 , wherein the complexing in Step (1) is performed by mixing the lithium metal oxide and the nickel precursor in distilled water and stirring the mixture for 0.5 to 12 hours. 
     
     
         14 . The method of  claim 10 , wherein the complexing in Step (1) is able to be performed in the presence of a complexing agent, and the complexing agent is at least one selected from the group consisting of ammonium hydroxide, ammonium fluoride, and hydrazine compounds. 
     
     
         15 . The lithium metal oxide of  claim 10 , wherein the nickel oxide layer comprises at least one selected from the group consisting of NiO a , NiO, and Ni 2 O 3 , and a satisfies 1<a≦1.5. 
     
     
         16 . The method of  claim 10 , wherein the heat treatment in Step (2) is performed at a temperature of 200 to 900° C. 
     
     
         17 . The method of  claim 10 , wherein the heat treatment in Step (2) is performed under an inert gas atmosphere, and the inert gas is at least one selected from the group consisting of helium, nitrogen, argon, neon, and xenon. 
     
     
         18 . The method of  claim 10 , wherein the lithium metal oxide is represented by Formula 1 below:
   Li x M y O z   [Formula 1]
   in Formula 1 above, M is at least one selected from the group consisting of Ti, Sn, Cu, Pb, Sb, Zn, Fe, In, Al, and Zr; and   x, y, and z are determined according to oxidation number of M.   
     
     
         19 . The method of  claim 10 , wherein the lithium metal oxide is at least one selected from the group consisting of Li 4 Ti 5 O 12 , LiTi 2 O 4 , Li 2 TiO 3 , and Li 2 Ti 3 O 7 . 
     
     
         20 . (canceled) 
     
     
         21 . A method of preparing a negative electrode active material for a lithium secondary battery, the method comprising the preparation method of  claim 10 .