a fuel cell having a polymer electrolyte membrane containing fluorine atoms distributed along the polymer chains , and metal conductors and / or catalysts . the cell is protected from metal ion degradation of cell components , especially the polymer electrolyte , by a metal ion sequestering or chelating agent fixed in the cell or flowing through the cell . in a preferred embodiment , the metal ion - sequestering agent comprises a suitable number of metal ion - binding molecular crown moieties attached to polymer constituents in the electrolyte membrane or in electrodes .