NOVELTY - A nonaqueous electrolyte secondary battery comprises flat-shaped wound electrode component (14) inserted into an external casing such that winding axis is in a horizontal direction, positive electrode plate (11), negative electrode plate (12), nonaqueous electrolyte, and separator (13) at a winding end of the flat-shaped wound electrode component each face an upper surface side. The positive electrode plate has positive mix layer formed on the positive electrode core. The negative electrode plate has negative mix layer formed on the negative electrode core.    USE - Nonaqueous electrolyte secondary battery is used for driving power supply of electric vehicle and hybrid electric vehicle.    ADVANTAGE - The nonaqueous electrolyte secondary battery has excellent electric current interruption mechanism with increased generation amount of carbon dioxide gas, and is safe.    DETAILED DESCRIPTION - A nonaqueous electrolyte secondary battery comprises flat-shaped winding electrode component inserted into an external casing such that winding axis is in a horizontal direction, positive electrode plate, negative electrode plate, and separator at a winding end of the flat-shaped winding electrode component each face an upper surface side. The positive electrode plate has positive mix layer formed on the positive electrode core. The negative electrode plate has negative mix layer formed on the negative electrode core. The flat-shaped wound electrode component is wound by flat shape in the state by which positive electrode plate and negative electrode plate are mutually insulated on both sides of the separator. The flat-shaped wound electrode component has positive electrode core exposure portion (15) formed in one edge portion of the flat-shaped winding electrode component, and negative electrode core exposure portion formed in the other edge portion of flat-shaped wound electrode component. The positive electrode core exposure portion is connected to positive electrode electrical power collector. The negative electrode core exposure portion is connected to anode collector. The positive mix layer contains lithium carbonate. The nonaqueous electrolyte secondary battery is provided with pressure-responsive current cut-off mechanism.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of the nonaqueous electrolyte secondary battery. (Drawing includes non-English language text)    Positive electrode plate (11)    Negative electrode plate (12)    Separator (13)    Flat-shaped winding electrode component (14)    Positive electrode core exposure portion (15)