In an improved electrochemical fuel cell assembly, a reactant flow path extends
substantially linearly across the electrochemically active area of an electrode.
The electrode has an in-plane nonuniform structure in its electrochemically active
area as the active area is traversed in the direction of the substantially linear
reactant flow path. Embodiments in which the structure of the fuel cell electrode
varies substantially symmetrically along the reactant flow path are particularly
preferred in fuel cells in which the flow direction of a reactant is periodically reversed.
