Lithium secondary battery

Abstract

A lithium secondary battery according to an embodiment of the present disclosure includes a cathode, an anode and a non-aqueous electrolyte. The anode includes an anode active material which contains a mixture of an artificial graphite and a natural graphite. A sphericity of the natural graphite is 0.96 or more. The lithium secondary battery including the anode has improved life-span and power properties.

What is claimed is: 
     
         1 . A lithium secondary battery, comprising:
 a cathode;   an anode comprising an anode active material comprised of a mixture of an artificial graphite and a natural graphite, wherein a sphericity of the natural graphite is 0.96 or more; and   a non-aqueous electrolyte.   
     
     
         2 . The lithium secondary battery of  claim 1 , wherein the sphericity of the natural graphite is 0.98 or more. 
     
     
         3 . The lithium secondary battery of  claim 1 , wherein an average particle diameter (D 50 ) of the natural graphite is in a range from 9 μm to 14 μm. 
     
     
         4 . The lithium secondary battery of  claim 1 , wherein a half value width in a particle size distribution of the natural graphite is 10 μm or less. 
     
     
         5 . The lithium secondary battery of  claim 1 , wherein a half value width in a particle size distribution of the natural graphite is 9 μm or less. 
     
     
         6 . The lithium secondary battery of  claim 1 , wherein a mixing weight ratio of the natural graphite and the artificial graphite is in a range from 10:1 to 1:1. 
     
     
         7 . The lithium secondary battery of  claim 1 , wherein an anode expansion rate represented by Equation 1 below is 20% or less:
   Anode expansion rate (%)=100×( T   2   −T   1 )/( T   1 )  [Equation 1]
   wherein, in the Equation 1, T 1  is a thickness of the anode at 0% SOC (State Of Charge), and T 2  is a thickness of the anode at 100% SOC.   
     
     
         8 . The lithium secondary battery of  claim 1 , wherein an average particle diameter (D 50 ) of the natural graphite is in a range from 9 μm to 14 μm;
 a half value width in a particle size distribution of the natural graphite is 10 μm or less; 
 a mixing weight ratio of the natural graphite and the artificial graphite is in a range from 10:1 to 1:1; and 
 an anode expansion rate represented by Equation 1 below is 20% or less:
   Anode expansion rate (%)=100×( T   2   −T   1 )/( T   1 )  [Equation 1]
 
 
 wherein, in the Equation 1, T 1  is a thickness of the anode at 0% SOC (State Of Charge), and T 2  is a thickness of the anode at 100% SOC.