Lithium Secondary Battery

A lithium secondary battery may include an electrode assembly including a positive electrode including a positive electrode active material, a negative electrode including a negative electrode active material, and a separator disposed between the positive electrode and the negative electrode; an electrolyte; and a battery case accommodating the electrode assembly and the electrolyte, wherein the positive electrode active material includes a first lithium nickel-based oxide having at least one of a single particle type composed of one nodule and a pseudo-single particle type which is an aggregate of 30 or less nodules, in 50 wt % or more on the basis of the total weight of the positive electrode active material, and the negative electrode active material is composed of a Si/C composite and a carbon-based negative electrode active material.