a novel plenum - free gas diffusion electrode assembly , and cells utilizing the same , embodying a catalyzed preferably carbon cloth or paper sheet contacting on one side a solid metal supporting current collector sheet , as with the aid of a conductive adhesive layer , and preferably though not always essentially carrying an electrolyte - permeable aqueous polymeric hydrogel coating on the other side , with the current collector sheet provided with gas inlet openings occupying a very minor portion of the surface of the current collector sheet .