Disclosed is a lithium secondary battery comprising a cathode (C), an anode (A), a separator and an electrolyte, wherein the battery has a weight ratio (A/C) of anode active material (A) to cathode active material (C) per unit area of each electrode of between 0.44 and 0.70, and shows a charge cut-off voltage of between 4.35V and 4.6V. The high-voltage lithium secondary battery satisfies capacity balance by controlling the weight ratio (A/C) of anode active material (A) to cathode active material (C) per unit area of each electrode. Therefore, it is possible to significantly increase the available capacity and average discharge voltage of a battery using a lithium/cobalt-based cathode active material, which shows an available capacity of about 50% in a conventional 4.2V-battery. Additionally, it is possible to significantly improve battery safety under overcharge conditions, and thus to provide a high-voltage and high-capacity lithium secondary battery having excellent safety and long service life.