NOVELTY - A device comprises an electrochemical conversion assembly containing several electrochemical conversion cells (20); several electrically conductive bipolar plates (30), where the cells are disposed between adjacent bipolar plates; and several conversion assembly gaskets (40) molded onto corresponding bipolar plates. The conversion assembly gaskets comprise a mixture including polyvinylidene fluoride (PVDF).    USE - As device e.g. vehicle with motive power (claimed).    ADVANTAGE - The bipolar plate are electrochemical stable, and electrically conductive. The gasket acts as a seal against leakage, and minimizes leakage of fluid reactant and product streams in the electrochemical conversion assembly. The gasket is electrochemically stable, compressible, inexpensive and available. The gasket is made of material that has a superior chemical stability to facilitate its effectiveness in the gasket; and exhibits excellent thermal stability.    DETAILED DESCRIPTION - A device comprises an electrochemical conversion assembly containing several electrochemical conversion cells (20); several electrically conductive bipolar plates (30), where the electrochemical conversion cells are disposed between adjacent bipolar plates; and several conversion assembly gaskets (40) molded onto corresponding bipolar plates. The conversion assembly gaskets comprise a mixture including polyvinylidene fluoride (PVDF). The mixture comprises a PVDF homopolymer having density of 1.76 cm3, melting point of 158-160degreesC, dielectric strength of 6 kV/mm, maximum water absorption of 0.02 wt.%, an elongation at breakage of 100%, and an elongation at yield of 10%. The PVDF homopolymer exhibits a 1% mass loss in nitrogen at a temperature of 410degreesC; and a glass transition temperature of -39degreesC. The PVDF homopolymer comprises a volume resistivity of 1x1015 ohm-cm at 23degreesC; a tensile modulus of 1310 Mpa. The mixture comprises at least one solvent. The mixture comprises 60 wt.% PVDF homopolymer and 40 wt.% propylene carbonate. The bipolar plates comprise a flowfield (32) defined between opposite, electrically conductive sides of the bipolar plate. The device further comprises a fuel processing system or fuel source for providing a hydrogenous gas to the electrochemical conversion assembly. An INDEPENDENT CLAIM is included for fabricating the electrochemical conversion assembly involving forming a mixture of PVDF and a solvent by dissolving the PVDF in the solvent; applying the mixture onto bipolar plates; and heating the mixture under pressure to form conversion assembly gaskets on the bipolar plates.    DESCRIPTION OF DRAWING(S) - The figure shows a cross-sectional of the bipolar plate with gasket.    conversion cell (20)    bipolar plate (30)    flow-field channel (35)    electrically conductive sides of plate (36, 38)    gasket. (40)