NOVELTY - A flat fuel cell assembly (100) comprises a membrane electrode assembly (MEA) (102) containing a proton conducting membrane (110), an anode catalyst layer (111), a cathode catalyst layer (113), an anode gas diffusion layer (GDL) (112) and a cathode GDL (114); a cathode porous current collector (104); an anode porous current collector (106); and a gas barrier material layer (108).    USE - As flat fuel cell assembly (claimed) useful as energy source.    ADVANTAGE - The flat fuel cell assembly is capable of diffusing the water at the cathode part into the anode part for being reused, and has a simple manufacturing method, thus enhancing the energy conservation efficiency of the fuel. The manufacturing method is relatively simple and fewer elements are required, thus saving the manufacturing cost. The assembly does not need to change the internal structure of the MEA in the current fuel cell. The flat fuel cell assembly utilizes the high concentration fuel to perform the reaction, thus enhancing the energy conversion efficiency of the fuel. The hydrophobic porous material layer maintains an extremely high and uniform humidity on the gas barrier material layer, so as to achieve a more preferred effect of recycling the water.    DETAILED DESCRIPTION - A flat fuel cell assembly (100) comprises a membrane electrode assembly (MEA) (102) containing a proton conducting membrane (110), an anode catalyst layer (111), a cathode catalyst layer (113), an anode gas diffusion layer (GDL) (112) and a cathode GDL (114), where the anode catalyst layer and the cathode catalyst layer are respectively disposed on two sides of the proton conducting membrane, and the anode GDL and the cathode GDL are respectively disposed on the anode catalyst layer and the cathode catalyst layer; a cathode porous current collector (104), disposed on one side of the cathode GDL of the MEA; an anode porous current collector (106), disposed on one side of the anode GDL of the MEA; and a gas barrier material layer (108), disposed on the cathode porous current collector, and having at least one opening for exposing the surface of the cathode porous current collector. The flat fuel cell assembly further comprises a hydrophobic porous material layer completely covering the cathode porous current collector.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic structural view of a flat fuel cell assembly.    Flat fuel cell assembly (100)    Membrane electrode assembly (102)    Cathode porous current collector (104)    Anode porous current collector (106)    Gas barrier material layer (108)    Proton conducting membrane (110)    Anode catalyst layer (111)    Anode gas diffusion layer (112)    Cathode catalyst layer (113)    Cathode gas diffusion layer. (114)