Method to manufacture composite polymer electrolyte membranes coated with inorganic thin films for fuel cells

Abstract

The present invention relates to a method for manufacturing composite polymer electrolyte membranes coated with inorganic thin films for fuel cells using a plasma enhanced chemical vapor deposition (PECVD) method or a reactive sputtering method, so as to reduce the crossover of methanol through polymer electrolyte membranes for fuel cells and enhance the performance of the fuel cells. The manufacturing method of composite polymer electrolyte membranes coated with inorganic thin films for fuel cells according to the present invention is characterized to obtain composite membranes by coating the surface of commercial composite polymer electrolyte membranes for fuel cells with inorganic thin films using a PECVD method or a reactive sputtering method. The inorganic materials to form the inorganic thin films are chosen one or more from the group comprising silicon oxide (SiO 2 ), titanium oxide (TiO 2 ), zirconium oxide (ZrO 2 ), zirconium phosphate (Zr(HPO 4 ) 2 ), zeolite, silicalite, and aluminum oxide (Al 2 O 3 ). The present invention, by coating the polymer electrolyte membranes for fuel cells with inorganic thin films via a PECVD method or a reactive sputtering method, reduces the methanol crossover sizably without seriously reducing the ionic conductivity of polymer electrolyte membranes, thereby, when applied to fuel cells, realizes a high performance of fuel cells.

1 . A composite polymer electrolyte membrane coated with inorganic thin films for fuel cells manufactured by a method comprising coating the surface of polymer electrode membranes with inorganic thin films using a plasma enhanced chemical vapor deposition (PECVD) method or a reactive sputtering method.  
     
     
         2 . The composite polymer electrolyte membrane of  claim 1 , wherein the inorganic thin films are chosen from one or more of the group consisting of silicon oxide (SiO 2 ), titanium oxide (TiO 2 ), zirconium oxide (ZrO 2 ), zirconium phosphate (Zr(HPO 4 ) 2 ), zeolite, silicalite, and aluminum oxide (Al 2 O 3 ).  
     
     
         3 . The composite polymer electrolyte membrane of  claim 1 , wherein the polymer electrolyte membranes are perfluorosulfonic acid membranes, electrolyte membranes made of proton conducting hydrocarbon materials, or electrolyte membranes made of proton conducting fluorine materials.  
     
     
         4 . The composite polymer electrolyte membrane of  claim 1 , wherein the PECVD method used to make the composite polymer electrolyte membrane uses reactants comprising one or more monomers selected from the group consisting of organic metal compounds containing aluminum, titanium, silicon, and zirconium in conjunction with one or more gases selected from the group consisting of oxygen, nitrogen, hydrogen, steam, and argon.  
     
     
         5 . The composite polymer electrolyte membrane of  claim 1 , wherein the reactive sputtering method used to make the composite polymer electrolyte membrane uses a 99% or higher purity metal target such as Si, SiO2, SiNH, Al, Zr, or Ti, and maintains its initial pressure at a high vacuum range of 1.0×10 −3  torr to 1.0×10 −6  torr.  
     
     
         6 . The composite polymer electrolyte membrane of  claim 1 , wherein the PECVD or reactive sputtering method used to make the composite polymer electrolyte membrane has as microwave power range of about 10 watts to about 500 watts.  
     
     
         7 . The composite polymer electrolyte membrane of  claim 1 , wherein the reaction chamber pressure for the PECVD method used to make the composite polymer electrolyte membrane is in the range of about 1.0 to about 1000 millitorr.  
     
     
         8 . The composite polymer electrolyte membrane of  claim 1 , wherein the PECVD method or reactive sputtering method used to make the composite polymer electrolyte membrane has an argon pretreatment electromagnetic wave power in the range of about 10 watts to about 500 watts.  
     
     
         9 . The composite polymer electrolyte membrane of  claim 1 , wherein the PECVD method used to make the composite polymer electrolyte membrane has an argon pretreatment pressure of about 1.0 to about 500 millitorr.  
     
     
         10 . The composite polymer electrolyte membrane of  claim 1 , wherein the reaction chamber pressure for the PECVD method used to make the composite polymer electrolyte membrane is in the range of about 10 to about 500 millitorr.  
     
     
         11 . The composite polymer electrolyte membrane of  claim 1 , wherein the thickness of the inorganic thin films is in the range of about 1.0 to about 500 nm.  
     
     
         12 . The composite polymer electrolyte membrane of  claim 1 , wherein the composite membrane is further manufactured by a method comprising a step of coating the surface of an electrolyte membrane with a proton-conducting ionomer solution after coating the inorganic thin film on the electrolyte membrane surface, so as to enhance contact with the electrodes during manufacturing.  
     
     
         13 . A membrane-electrode assembly (MEA) employing composite polymer electrolyte membranes coated with inorganic thin films manufactured by a method comprising coating the surface of polymer electrode membranes with inorganic thin films using a plasma enhanced chemical vapor deposition method or a reactive sputtering method.  
     
     
         14 . A fuel cell employing composite polymer electrolyte membranes coated with inorganic thin films, or employing an MEA containing composite polymer electrolyte membranes with inorganic thin films, wherein the composite polymer membranes are manufactured by a method comprising coating the surface of polymer electrode membranes with inorganic thin films using a plasma enhanced chemical vapor deposition method or a reactive sputtering method.