NOVELTY - An electrochemical cell stack (101) comprises two electrochemical cells (103-1, 103-2) arranged in series in a bipolar configuration and electrically coupled to one another. The two electrochemical cells comprise a proton exchange membrane (17) having a first and second face, an anode (19) positioned along the first face of the proton exchange membrane, a cathode (21) positioned along the second face of the proton exchange membrane, and a compression pad (105). The compression pad is electrically-conductive, resiliently compressible and porous and having an inner face and an outer face.    USE - As electrochemical cell stack (claimed) for converting water to oxygen and hydrogen.    ADVANTAGE - The electrically-conductive, resiliently compressible and porous compression pad permits the passage of fluids and replacing multilayer screen of electrolysis cell or the carbon fiber paper or carbon fiber cloth of the fuel cell; and the pads can be arranged to the stack without requiring separate compression pad; and prevents fretting corrosion associated with the multi-layer screen, thus reduced the cost and weight of the cell.    DETAILED DESCRIPTION - An electrochemical cell stack (101) comprises two electrochemical cells (103-1, 103-2) arranged in series in a bipolar configuration and electrically coupled to one another. The two electrochemical cells comprise a proton exchange membrane (17) having a first and second face, an anode (19) positioned along the first face of the proton exchange membrane, a cathode (21) positioned along the second face of the proton exchange membrane, and a compression pad (105) for use in defining a cathodic fluid cavity. The compression pad is electrically-conductive, resiliently compressible and porous and having an inner face and an outer face.    INDEPENDENT CLAIMS are also included for the following:    (1) an electrically-conductive, resiliently compressible, fluid diffusion medium suitable for use in an electrochemical cell comprising a first layer containing carbon fibers and at least one binder; and    (2) the preparation of the electrically-conductive, resiliently compressible, fluid diffusion medium involving either mixing the carbon fibers and the at least one binder, laying down the mixture, and heating the mixture to a temperature to melt the binder under conditions of pressure sufficient to form a sheet of uniform thickness; or mixing the carbon fibers and the at least one thermoplastic binder, heating the mixture until the thermoplastic binder begins to melt, dispersing the product, laying down the dispersed material to form a blanket-type product, and heating the blanket-type product to a temperature to melt the thermoplastic binder under conditions of pressure to form a sheet of uniform thickness.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of the proton exchange membrane electrolysis stack.    proton exchange membrane (17)    anode (19)    cathode (21)    electrochemical cell stack (101)    electrochemical cells (103-1, 103-2)    compression pad. (105)