Negative electrode active material, negative electrode including the negative electrode active material, and secondary battery including the negative electrode

Abstract

A negative electrode active material which includes a core including SiO x (0<x<2), a shell disposed on the core and includes lithium silicate, and a coating layer disposed on the shell and includes carbon nanotubes. Also, a method of preparing a negative electrode active material as well as a negative electrode and a battery including the same.

1 . A negative electrode active material, comprising:
 a core comprising SiO x , wherein 0<x<2;   a shell disposed on the core, wherein the shell comprises lithium silicate; and   a coating layer disposed on the shell, wherein the coating layer comprises carbon nanotubes.   
     
     
         2 . The negative electrode active material of  claim 1 , wherein the shell has a thickness of 10 nm to 1 μm. 
     
     
         3 . The negative electrode active material of  claim 1 , wherein the lithium silicate comprises at least one of Li 2 SiO 3  and Li 2 Si 2 O 5 . 
     
     
         4 . The negative electrode active material of  claim 1 , wherein the lithium silicate is present in an amount of 1 wt % to 45 wt % based on a total weight of the negative electrode active material. 
     
     
         5 . The negative electrode active material of  claim 1 , wherein the coating layer has a thickness of 10 nm to 1 μm. 
     
     
         6 . The negative electrode active material of  claim 1 , wherein the carbon nanotubes have a diameter of 1 nm to 150 nm, and
 the carbon nanotubes have a length of 100 nm to 5 μm.   
     
     
         7 . The negative electrode active material of  claim 1 , wherein the carbon nanotubes are present in an amount of 0.1 wt % to 20 wt % based on a total weight of the negative electrode active material. 
     
     
         8 . A method of preparing a negative electrode active material, the method comprising:
 mixing SiO x  particles and Li 2 CO 3 , wherein 0<x<2; and   performing a heat treatment on the mixed SiO x  particles and Li 2 CO 3  with a catalyst in a H 2  gas atmosphere.   
     
     
         9 . The method of  claim 8 , wherein a weight ratio of the SiO x  particles to the Li 2 CO 3  is in a range of 1:0.111 to 1:0.667. 
     
     
         10 . The method of  claim 8 , wherein the heat treatment is performed at a temperature range of 800° C. to 1,200° C. 
     
     
         11 . The method of  claim 8 , wherein the catalyst comprises at least one oxide selected from the group consisting of iron (Fe) and calcium (Ca). 
     
     
         12 . The method of  claim 8 , wherein the H 2  gas atmosphere is formed by introducing H 2  into the mixed SiO x  particles and Li 2 CO 3  at a flow rate of 500 sccm to 1,000 sccm for a time period of 30 minutes to 2 hours. 
     
     
         13 . The method of  claim 8 , further comprising:
 performing an acid treatment on the heat-treated SiO x  particles and Li 2 CO 3  after of performing the heat treatment.   
     
     
         14 . A negative electrode comprising the negative electrode active material of  claim 1 . 
     
     
         15 . The negative electrode of  claim 14 , further comprising graphite-based active material particles. 
     
     
         16 . A secondary battery comprising:
 the negative electrode of  claim 15 ;   a positive electrode;   a separator disposed between the positive electrode and the negative electrode; and   an electrolyte.