NOVELTY - A lithium secondary battery has a cathode with a cathode mixture layer sintered and located on a cathode current collector. The mixture layer contains a cathode conductive agent comprising a graphite material (3-20 mass%), a cathode binder, and cathode active material particles (20, 21) having an average particle size of 5.0-15.0 microns before being charged and made of a material containing silicon. A theoretical electrical capacity ratio of an anode of the battery to the cathode is less than or equal to 1.0.    USE - The lithium secondary battery is used for driving power sources for mobile information terminals, e.g. mobile telephones, notebook computers, and personal digital assistants. The battery is used for in-vehicle power sources for electric automobiles or hybrid automobiles.    ADVANTAGE - Lithium secondary battery has improved initial charge-discharge efficiency and enhanced charge-discharge cycle performance.    DETAILED DESCRIPTION - Lithium secondary battery comprises:    (a) an anode;    (b) a non-aqueous electrolyte; and    (c) a cathode comprising a cathode current collector and a cathode mixture layer that contains a cathode conductive agent, a cathode binder, and cathode active material particles made of a material containing silicon.    The cathode mixture layer is sintered and located on the cathode current collector. The cathode active material particles have an average particle size of 5.0-15.0 microns before being charged. The cathode conductive agent comprises a graphite material having an average particle size of 2.5-15.0 microns. The amount of the graphite material added is 3-20 mass% with respect to the cathode active material. A theoretical electrical capacity ratio of the anode to the cathode is less than or equal to 1.0. The graphite material has a Brunauer-Emmett-Teller specific surface area of less than or equal to 15 m2/g.    DESCRIPTION OF DRAWING(S) - The figure is a view schematically illustrating an interior of the cathode before and after a charge-discharge operation.    Cathode active material particles (20, 21)