Patent ID: 7790220

Claim:
A method for manufacturing composite membranes for a fuel cell, comprising a step of coating a surface of polymer electrolyte membrane with inorganic thin film using a plasma enhanced chemical vapor deposition (PECVD) method, thereby obtaining the composite membrane, wherein inorganic material of the inorganic thin film is one or more selected from the group consisting of silicon oxide (SiO 2 ), titanium oxide (TiO 2 ), zirconium oxide (ZrO 2 ), zirconium phosphate (Zr(HPO 4 ) 2 ), silicalite, and aluminum oxide (Al 2 O 3 ); the inorganic thin film is made by using one or more organic metal compound(s) selected from the group consisting of trimethyl disiloxanes (TMDSO), hexamethyl disilane, tetramethyl orthosilicate, tetrabutyl orthosilicate, tetra-isopropyl orthosilicate, aluminium methoxide, aluminium ethoxide, aluminium butoxide, aluminium isopropoxide, titanium ethoxide, titanium methoxide, titanium butoxide, titanium isopropoxide, zirconium ethoxide, and zirconium butoxide in conjunction with one or more gases selected from the group consisting of nitrogen, hydrogen, steam, and argon; the inorganic thin film has a thickness of 1.0 nanometer (nm) to 500 nm; the composite membranes have an ionic conductivity of 0.071 S/cm or more and the composite membranes have a characteristic factor of 54 Ω −1 cm −3 s or more, wherein the characteristic factor equals (ionic conductivity/methanol permability)×10 −3 .