Lithium secondary battery

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 0.98 or more;
• and
• a non-aqueous electrolyte,
• wherein an average particle diameter (D50) of the natural graphite is in a range from 9 μm to 14 μm, and a mixing weight ratio of the natural graphite and the artificial graphite is in a range from 9:1 to 1:1;
• and
• an anode expansion rate represented by Equation 1 below is 20% or less:
• anode expansion rate (%)=100×(T2-T1)/(T1) [Equation 1]
• wherein T1 is a thickness of the anode at 0% state of charge (SOC), and T2 is a thickness of the anode at 100% SOC;
• and
• wherein a pellet density change rate of the natural graphite which is represented by Equation 2 is 0.06 or less:
• Pellet density change rate=(Da-Db)/(a-b) [Equation 2]
• wherein Da represents a pellet density (g/cc) measured by inputting 2.5 g of the natural graphite in a hole with a 1 cm diameter and then applying a pressure of 8 kN for 5 seconds, Db represents a pellet density measured by applying a pressure of 1 kN for 5 seconds, a represents 8 kN and b represents 1 kN.