A pouch-type flexible film battery, including: (a) a cathode structure including a cathode pouch, a cathode conductive carbon layer, and a cathode layer; (b) an anode structure including an anode pouch, an anode conductive carbon layer, and an anode layer; and (c) a polymer electrolyte layer that is provided between the cathode and anode structures, that is bonded to the cathode layer and to the anode layer, and that is a gel-type electrolyte having adhesive properties and including a cellulose-based polymer.