Lithium secondary battery and method of preparing anode for lithium secondary battery

1. A lithium secondary battery, comprising:

a cathode;

a separation layer; and

an anode facing the cathode with the separation layer interposed therebetween, wherein the anode comprises:

an anode current collector; and

an anode active material layer formed on the anode current collector, the anode active material layer including an anode active material including natural graphite or artificial graphite and a conductive additive,

wherein a particle size of the anode active material is from about 5 μm to about 30 μm,

wherein the conductive additive includes an expandable graphite having a particle diameter of 5 μm to 10 μm,

wherein a porosity of the anode active material layer is from 19% to 24%, and

wherein the expandable graphite is in an expanded state, and an amount of the expandable graphite is in a range from 1 wt % to % 5 wt % based on a total weight of the anode active material layer.

2. The lithium secondary battery according to claim 1 , wherein the particle diameter of the expandable graphite is in a range from 5 μm to 7 μm.

3. The lithium secondary battery according to claim 1 , wherein an expansion ratio of the expandable graphite is from 150% to 500%.

4. The lithium secondary battery according to claim 1 , wherein the anode active material layer further includes at least one of a carbon-based conductive agent and a metal-based conductive agent.

5. The lithium secondary battery according to claim 1 , wherein the anode active material layer includes pores formed by an elastic deformation of the expandable graphite.

6. The lithium secondary battery according to claim 1 , wherein a density of the anode active material layer is from 1.4 g/cc to 1.9 g/cc.