NOVELTY - A non-aqueous electrolyte secondary battery (1) comprises electrode assembly (20) including positive electrode having particles of lithium transition metal compound as positive electrode active material, negative electrode opposed to positive electrode, and separator disposed between them; non-aqueous electrolyte containing lithium difluorophosphate; and container housing the assembly and the electrolyte, where battery capacity is not less than 21 Ah, and mean particle diameter (D50) of the particles of lithium transition metal compound is not less than 5 mu m to not greater than 15 mu m, and (D90-D10)/D50 is under 1.1.    USE - As non-aqueous electrolyte secondary battery (claimed) used in electric vehicles, hybrid vehicles, hybrid cars, and the like.    ADVANTAGE - The battery capacity is not less than 21 Ah. The battery has superior storage stability in addition to high output and improved low-temperature output characteristics.    DETAILED DESCRIPTION - A non-aqueous electrolyte secondary battery (1) comprises an electrode assembly (20) including a positive electrode containing particles of a lithium transition metal compound as a positive electrode active material, a negative electrode opposed to the positive electrode, and a separator disposed between the positive electrode and the negative electrode; a non-aqueous electrolyte containing lithium difluorophosphate; and a container housing the electrode assembly and the non-aqueous electrolyte, where the battery capacity is not less than 21 Ah, and the mean particle diameter (D50) of the particles of the lithium transition metal compound is not less than 5 mu m to not greater than 15 mu m, and (D90-D10)/D50 is under 1.1.    DESCRIPTION OF DRAWING(S) - The figure shows sectional view of non-aqueous electrolyte secondary battery.    Non-aqueous electrolyte secondary battery (1)    Container (10)    Container body (11)    Sealing plate (12)    Positive electrode terminal (13)    Positive electrode collector (15)    Electrode assembly (20)