(US4640876-A)      A single fuel cell (20) is built up from a number of plane members (21,32,42,24). A number of such cells are stacked together to constitute a fuel cell structure. Each fuel cell in the structure requires access to three independent fluid circuits: an electrolyte circuit including an inlet orifice (88A,98A) and an outlet orifice (88B,98B); a gas fuel circuit including inlet and outlet orifices (108); and an oxidant circuit which may be constituted by inlets and outlets in communication with ambient air. In the final structure, these circuit must be effectively sealed from one another and from the surroundings (except for the special case of ambient air oxidant). Unwanted seepage is prevented between adjacent ones of the plane members (21,32,42,24) due to defects in planeness and parallelism of the individual plane members.    This is done by surrounding an area to be sealed off from another area by a rib which stands proud of the surface of the associated plane member and which is associated with at least one groove. When the stack is assembled the ribs are ideally deformed and received in the associated grooves, but in the vicinity of non-ideal portions of the plane members the ribs serve to block gaps through which the fluids would otherwise pass. (20pp)n    (DE3526614-C2)      A fuel cell or battery comprises a stack of separate elements and is sealed by and plates (2,3) with end terminals (4,5).    The electrolyte passes into the battery via orifices (6) and then out again via orifices (7). The gaseous fuel, e.g. hydrogen, passes into the battery via orifices (8) and is drawn off via orifices (2). The gaseous oxygen carrier, e.g. air, enters the battery via the ends of grooves (105) formed on the surface of the battery, and leaves via corresp. orifices on the bottom of the battery.    A distribution circuit is provided for the electrolytes and for the fuel. At least one rib or fin is made of a material which deforms under pressure.    ADVANTAGE -   Sealing provided in battery in simple manner without making structure unstable.