NOVELTY - The non-aqueous secondary battery comprises cathode containing active material having double structured graphite particle comprising natural graphite particle on core portion surface. The natural graphite has face distances (d002) of (002) surface of 0.34 nm or less, and average particle diameter of 15-40 mum. The amount of lithium occlusion during complete charging of battery is 220-270 mAh per 1 g of cathode active material.    USE - For electrical storage systems such as solar power generators, and electric vehicles.    ADVANTAGE - The non-aqueous secondary battery has high-energy capacity and volume energy density, and has excellent cycle life property and safety. Even when the battery is repeatedly charged and discharged, the capacity of battery is maintained at high value.    DETAILED DESCRIPTION - The non-aqueous secondary battery contains anode, cathode, separator and non-aqueous electrolyte containing lithium salt, stored in battery container. The battery has flat shape having thickness of less than 12 mum, energy capacity of 30 Wh or more and volume energy of 180 Wh/I or more. The cathode contains active material having double structured graphite particle, which is covered with amorphous carbon, and comprise natural graphite particle on core portion surface. The natural graphite has face distances (d002) of (002) surface of 0.34 nm or less according to X-ray wide angle diffraction method, average particle diameter of 15-40 mum and tap density of more than 0.8 g/cm3. The face distances of the amorphous carbon is more than 0.34 nm. The amount of lithium occlusion during complete charging of battery is 220-270 mAh with respect to 1 g of cathode active material. The anode contains active material comprising lithium nickel manganese complex oxide of formula: LiaNibMncMdO2.    M = cobalt, aluminum or iron;    a = 1-1.1;    b, c = 0.3 or more and less than 0.5, and b is greater than or equal to c;    d = more than 0 and 0.4 or less;and    b+c+d = 1.    DESCRIPTION OF DRAWING(S) - The figure shows top view and side view of non-aqueous secondary battery for electrical storage systems.    upper cover (1)    bottom container (2)    anode terminal (3)    cathode terminal (4)    injecting nozzle (5)