NOVELTY - A non-aqueous electrolyte secondary battery comprises flat electrode assembly including positive electrode (18) and negative electrode (20), bottomed prismatic hollow outer can (25) storing flat electrode assembly and a non-aqueous electrolyte and having an opening portion; and sealing plate sealing the opening portion of hollow outer can, the flat electrode assembly having portion, other than the side facing sealing plate, covered with insulating sheet, where non-aqueous electrolyte containing lithium difluorophosphate at the time of making the non-aqueous electrolyte secondary battery.    USE - As non-aqueous electrolyte secondary battery (claimed), used as a power supply for driving electric vehicles (EVs) and hybrid electric vehicles    ADVANTAGE - The non-aqueous electrolyte secondary battery has excellent output characteristics in low temperature environment.    DETAILED DESCRIPTION - A non-aqueous electrolyte secondary battery comprises flat electrode assembly including a positive electrode (18) and a negative electrode (20), a bottomed prismatic hollow outer can (25) storing the flat electrode assembly and a non-aqueous electrolyte and having an opening portion; and a sealing plate sealing the opening portion of the hollow outer can, the flat electrode assembly having a portion, other than the side facing the sealing plate, covered with an insulating sheet, the non-aqueous electrolyte containing lithium difluorophosphate at the time of making the non-aqueous electrolyte secondary battery, and the outer surface area of a battery outer body including the hollow outer can and the sealing plate being greater than or equal to 350 cm2.    DESCRIPTION OF DRAWING(S) - The figure shows plan view of a prismatic non-aqueous electrolyte secondary battery.    Non-aqueous electrolyte secondary battery (10)    Positive electrode (18)    Negative electrode (20)    Insulating members (21, 22)    Sealing plate (23)    Hollow outer can (25)    Electrolyte pour hole (26)    Gas exhaust valve (28)