NOVELTY - An electrical device has electrical power generating element having positive electrode comprising positive electrode active material layer (15) containing active material, and negative electrode comprising negative electrode active material layer (13) containing active material. The coating amount of active material layer (13) is 3-11 mg/cm2. The positive electrode active material contains solid solution of active material in which element (M) chosen from aluminum, zirconium, titanium, niobium, boron, sulfur, tin, tungsten, molybdenum and vanadium exists on solid solution.    USE - Electrical device e.g. lithium-ion secondary battery (claimed) is used for driving power supply and auxiliary power supply. Uses include but are not limited to electric vehicle, fuel-cell vehicle, hybrid electric vehicle, bus, truck, passenger car, mobile telephone, and notebook personal computer.    ADVANTAGE - The electrical device has high capacity, high initial charge-discharge characteristics, long-term reliability and output characteristics.    DETAILED DESCRIPTION - An electrical device has an electrical power generating element having positive electrode comprising a positive electrode active material layer containing positive electrode active material formed on the surface of positive electrode current collector (12), a negative electrode comprising a negative electrode active material layer containing negative electrode active material formed on the surface of negative electrode current collector (11), and separator (17). The coating amount of negative electrode active material layer is 3-11 mg/cm2. The negative electrode active material comprises alpha (silicon material) and beta (carbon material), where alpha is 3-40, beta is 40-95, and alpha + beta is 80-98. The positive electrode active material layer contains 80-98 wt.% solid solution of positive electrode active material in which element (M) chosen from aluminum, zirconium, titanium, niobium, boron, sulfur, tin, tungsten, molybdenum and vanadium exists on the surface of solid solution. The solid solution of positive electrode active material comprises lithium-manganese-cobalt complex oxide of formula: Li1.5(NiaMnbCoc(Li)d)Oz (I), where a+b+c+d is 1.5, a+b+c is 1.1-1.4. The ratio of element (M) to the total content of a,b and c is 0.002-0.05.    DESCRIPTION OF DRAWING(S) - The drawing shows a cross-sectional schematic view of nonaqueous electrolyte lithium-ion secondary battery.    Lithium-ion secondary battery (10)    Negative electrode current collector (11)    Positive electrode current collector (12)    Negative electrode active material layer (13)    Positive electrode active material layer (15)    Separator (17)