NOVELTY - A nonaqueous secondary battery (100) consists of a positive electrode, a negative electrode, a nonaqueous electrolyte, and a separator. The positive electrode has a positive mix layer. The positive mix layer contains primary positive electrode active material and secondary positive electrode active material containing lithium-containing complex oxide (I). The primary positive electrode active material contains cobalt. The secondary positive electrode active material contains cobalt, nickel, and manganese. The positive mix layer has density of 3.4 g/cm3 or less.    USE - Nonaqueous secondary battery e.g. lithium-ion secondary battery is used as power supply for mobile telephone, notebook-type personal computer, and electric vehicle.    ADVANTAGE - The nonaqueous secondary battery has excellent heavy current characteristics, and high capacity.    DETAILED DESCRIPTION - A nonaqueous secondary battery consists of a positive electrode, a negative electrode, a nonaqueous electrolyte, and a separator. The positive electrode has a positive mix layer. The positive mix layer contains primary positive electrode active material and secondary positive electrode active material containing lithium-containing complex oxide of formula: Li1+yMO2 (I), where M is cobalt, nickel, titanium, chromium, iron, copper, zinc, aluminum, germanium, tin, magnesium, silver, thulium, niobium, boron, phosphorus, zirconium, calcium, strontium, barium, molybdenum, gallium, and manganese, and y is -0.15-0.15 (including -0.15 and 0.15). The primary positive electrode active material contains cobalt. The secondary positive electrode active material contains cobalt, nickel, and manganese. The content of cobalt with respect to element (M) in whole element of primary positive electrode active material is 90-100 mol%. The content of cobalt, nickel, and manganese with respect to element (M) in whole element of secondary positive electrode active material is 10-35 mol%, 45-65 mol%, and 10-35 mol%, respectively. The content of primary positive electrode active material is 20 %mass or more with respect to all positive electrode active materials contained in the positive mix layer. The positive mix layer has density of 3.4 g/cm3 or less. The negative electrode has a negative mix layer. The negative mix layer contains a material containing composition containing silicon oxide (SiOx, where x is 0.5-1.5 (including 0.5 and 1.5)) containing silicon and oxygen as constituent elements, and graphite as a negative electrode active material. A complex is formed by conjugating material of negative mix layer with a carbon material.    DESCRIPTION OF DRAWING(S) - The drawing shows the top view of nonaqueous secondary battery.    Positive electrode external terminal (11)    Negative electrode external terminal (21)    Nonaqueous secondary battery (100)    Exterior component (200)