NOVELTY - The non-aqueous electrolyte lithium-ion secondary battery useful as power supply for portable electronic devices e.g. cellular phones, comprises a cathode having a cathode active material layer, an anode, and a non-aqueous electrolyte. The cathode active material layer includes secondary particles of a lithium phosphate compound having olivine structure, and a fibrous carbon. An average particle diameter A of carbon material-coated primary particles constituting the secondary particles is greater than or equal to 50 nm and less than or equal to 500 nm.    USE - The non-aqueous electrolyte lithium-ion secondary battery is useful as power supply for portable electronic devices such as camera-integrated videotape recorders, cellular phones or laptop computers, and for electrical vehicles and hybrid electrical vehicles.    ADVANTAGE - The non-aqueous electrolyte lithium-ion secondary battery has high battery capacity and energy density, light weight, high-power discharging capacity and excellent cycle characteristics, and is compact and excellent in load characteristics.    DETAILED DESCRIPTION - The non-aqueous electrolyte lithium-ion secondary battery useful as power supply for portable electronic devices e.g. cellular phones, comprises a cathode having a cathode active material layer, an anode, and a non-aqueous electrolyte. The cathode active material layer includes secondary particles of a lithium phosphate compound having olivine structure, and a fibrous carbon. An average particle diameter A of carbon material-coated primary particles constituting the secondary particles is greater than or equal to 50 nm and less than or equal to 500 nm. A ratio B/A of a pore diameter B of the secondary particles to the average particle diameter A of the primary particles is greater than or equal to 0.10 and less than or equal to 0.75. INDEPENDENT CLAIMS are included for:    (1) a cathode active material; and    (2) a cathode.    DESCRIPTION OF DRAWING(S) - The diagram shows a cross-sectional view of a structure of a non-aqueous electrolytic solution battery.    Battery lid (14)    Spiral electrode body (20)    Band-like cathode (21)    Band-like anode (22)    Separator. (23)