NOVELTY - The battery has connection tabs extended from an end portion of a first metal current collector (14) at a first end portion of a first set of electrode layers (10, 100) and an end portion of a second metal current collector (15) at a first end portion of a second set of electrode layers (11, 101). A fixing element (13) fixes the end portions of the first and second metal current collectors at a first end portion of an electrode stack structure. Second end portions of the first and second electrode layers opposite to the first end portions of the first and second electrode layers are movable.    USE - Flexible secondary battery for use in a mobile electronic device. Uses include but are not limited to smart phones, smart pads, electronic books, watch-shaped telephones, mobile medical devices, game players, portable multimedia players (PMPs) and moving picture experts group (MPEG) audio layer-3 (MP3) players.    ADVANTAGE - The fixing element fixes layers of the electrode stack structure at the end portions of the electrode stack structure in a flexible manner, so that the electrode stack structure maintains stability within the flexible secondary battery even with repeated warping motion or bending motion of the opposed end portion. The battery is provided with a reinforcement element that is arranged around the connection tabs extended from the layers of the electrode stack structure and the fixing element, so that stable operational characteristics of the layers of the electrode stack structure can be maintained.    DETAILED DESCRIPTION - The fixing element is an adhesive or an adhesive-coated tape. The first set of electrode layers and a second set of electrode layers are a negative film, a positive film, a positive active material layer and a negative active material layer. The second metal current collector is a negative current collector. The first metal current collector is a positive current collector. An INDEPENDENT CLAIM is also included for a method for manufacturing a flexible secondary battery.    DESCRIPTION OF DRAWING(S) - The drawing shows a cross-sectional view of an electrode stack structure of a flexible secondary battery.    Electrode layers (10, 11, 100, 101)    Isolating layers (12)    Fixing element (13)    Metal current collectors (14, 15)