TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Composition: At least 20% or at least 50% of the weight of the polymeric material is conductive filler. The conductive filler is carbon filler with a diameter of 7 microns and thickness of at least 10 mils. The porous electronically conductive material is carbon fiber with a porosity of at least 60%.    TECHNOLOGY FOCUS - POLYMERS - Preferred Material: The polymeric material is thermoplastic polyurethane, polypropylene, syndiotactic polystyrene, vinyl ester resin, polyvinylidene fluoride, polytetrafluoroethylene or polyepoxide.    TECHNOLOGY FOCUS - ELECTRICAL POWER AND ENERGY - Preferred Plate: The plate comprises three layers of a porous conductive material. A solid layer of a polymeric material with a dispersion of at least 1 wt.% of conductive layer is between the first and second layers, and between the second and third layers.    TECHNOLOGY FOCUS - ELECTRONICS - Preferred Device: The electronic device has a thickness of at least 70 mils. Its porous electronically conductive material is a carbon fiber with a porosity of at least 70%. WIDER DISCLOSURE - Suitable porous electronically conductive materials include carbon paper, graphite paper, carbon felts, or other carbon-based composites, porous metal materials such as sintered metals, metal meshes, and metal screens, and solid, porous, electronically conductive polymers that are at least 1 mil thick. Suitable polymeric materials that contain the conductive filler include any thermoplastic or thermosetting polymer which is solid at ambient conditions (about 23 degreesC), stable under the operating conditions of the electrochemical cell, and can be mixed with a conductive filler and processed into the shape of a separator plate for use with electrochemical cells. Examples of such include polyolefins, polystyrenes, polyepoxides, polyurethanes, polytetrafluoroethylenes, polyacrylates, polyethylene terephthalate, polyvinylchloride, polyvinylidene fluoride, vinyl ester resins, acrylonitrile-butadiene-styrene copolymers, polyamides, polyesters, linear polyimides, liquid crystal polymers, and their blends or their copolymers. Suitable conductive fillers include electronically conductive grades of carbon black, carbon fibers, graphite, metal fibers and particles, and particles of intrinsically conductive polymers.