Negative active material for rechargeable lithium battery and rechargeable lithium battery including same

Abstract

A negative active material for a rechargeable lithium battery includes a composite of silicon and crystalline carbon, wherein the silicon has an average particle diameter (D50) of about 10 nm to about 150 nm, and the crystalline carbon has an average particle diameter (D50) of about 5 μm to about 20 μm, and an aspect ratio of about 4 to about 10.

What is claimed is: 
     
         1 . A negative active material for a rechargeable lithium battery, the negative active material comprising a composite of silicon and crystalline carbon,
 wherein the silicon has an average particle diameter (D 50 ) of about 10 nm to about 150 nm, and   the crystalline carbon has an average particle diameter (D 50 ) of about 5 μm to about 20 μm, and an aspect ratio of about 4 to about 10.   
     
     
         2 . The negative active material as claimed in  claim 1 , wherein the negative active material has an aspect ratio of about 1 to about 2.5. 
     
     
         3 . The negative active material as claimed in  claim 1 , wherein the silicon has an average particle diameter (D 50 ) of about 40 nm to about 120 nm. 
     
     
         4 . The negative active material as claimed in  claim 1 , wherein the crystalline carbon has an average particle diameter (D 50 ) of about 5 μm to about 10 μm. 
     
     
         5 . The negative active material as claimed in  claim 1 , wherein a mixing ratio of the silicon and the crystalline carbon is a weight ratio of about 1:9 to about 9:1. 
     
     
         6 . The negative active material as claimed in  claim 1 , wherein the silicon-carbon composite further includes an amorphous carbon coating layer on the surface thereof. 
     
     
         7 . The negative active material as claimed in  claim 1 , wherein an amount of the amorphous carbon coating layer is about 10 wt % to about 60 wt % based on total 100 wt % of the negative active material. 
     
     
         8 . A rechargeable lithium battery, comprising
 a negative electrode including the negative active material as claimed in  claim 1 ;   a positive electrode including a positive active material; and   a non-aqueous electrolyte.