Lithium Secondary Battery

A lithium secondary battery having high energy density and excellent lifetime characteristics includes: (1) a positive electrode containing a positive electrode active material in a single particle form having a Dof 5.5 μm to 8 μm; (2) a negative electrode containing a first negative electrode active material having a Si—C composite; and (3) an electrolyte. The irreversible capacity per unit area of the negative electrode is smaller than an irreversible capacity per unit area of the positive electrode.