PTFE coated Nafion proton conducting membranes for direct methanol fuel cells

The performances of direct methanol fuel cells (DMFC) are affected by the methanol cross-over, due to the concentration gradient and electrosmosis between the anodes and cathodes. In this study, Polytetrafluoroethylene (PTFE) has been sputter deposited on conventional proton conducting membranes, Nafion117. It was found that the problem of the methanol cross-over was eased by the PTFE coating. The properties of coated and uncoated Nafion117 were investigated by scanning electron microscopy, electron spectroscopy for chemical analysis, gas chromatography and AC impedance spectroscopy. The coated film can form a barrier layer between the methanol solution and the polymer membrane. The PTFE barrier layer can effectively retard the methanol molecules, whereas the proton conductivities were not significantly influenced. The conductivity/permeability ratio two times higher the conventional Nafion117 membrane has been achieved under an optimized coating time. This technique developed shows great potential for the applications in DMFCs.

[1]  Antonino S. Aricò,et al.  Investigation of a direct methanol fuel cell based on a composite Nafion®-silica electrolyte for high temperature operation , 1999 .

[2]  I. Hsing,et al.  Composite Nafion/polyvinyl alcohol membranes for the direct methanol fuel cell , 2002 .

[3]  J. Economy,et al.  Design of high efficiency polymeric cation exchange fibers , 2001 .

[4]  H. Na,et al.  Layer-by-layer self-assembly of in situ polymerized polypyrrole on sulfonated poly(arylene ether ketone) membrane with extremely low methanol crossover , 2009 .

[5]  B. Höhlein,et al.  Fuel cell power trains for road traffic , 1999 .

[6]  Felix Bauer,et al.  Microstructural characterization of Zr-phosphate–Nafion® membranes for direct methanol fuel cell (DMFC) applications , 2004 .

[7]  Ih. Oh,et al.  Modification of polymer electrolyte membranes for DMFCs using Pd films formed by sputtering , 2002 .

[8]  K. Miyatake,et al.  Investigation of direct methanol fuel cell performance of sulfonated polyimide membrane , 2006 .

[9]  Won Choon Choi,et al.  Modification of proton conducting membrane for reducing methanol crossover in a direct-methanol fuel cell , 2001 .

[10]  Y. Lee,et al.  Crosslinked poly(vinyl alcohol) membranes containing sulfonic acid group: proton and methanol transport through membranes , 2004 .

[11]  A. Fane,et al.  Sulfonation of cross‐linked asymmetric membranes based on polystyrene and divinylbenzene , 1994 .

[12]  Zhongyi Jiang,et al.  Proton conducting CS/P(AA-AMPS) membrane with reduced methanol permeability for DMFCs , 2008 .

[13]  G. Jung,et al.  Nafion/PTFE composite membranes for direct methanol fuel cell applications , 2005 .

[14]  Chun–Chen Yang.  Synthesis and characterization of the cross-linked PVA/TiO2 composite polymer membrane for alkaline DMFC , 2007 .

[15]  Soo-Bok Lee,et al.  Sulfonated polystyrene/PTFE composite membranes , 2005 .

[16]  Th. Grube,et al.  Critical assessment of power trains with fuel-cell systems and different fuels , 2000 .

[17]  P. Shen,et al.  Low methanol permeable sulfonated poly(phthalazinone ether sulfone) membranes for DMFCs , 2007 .

[18]  Thomas F. Fuller,et al.  XPS investigation of Nafion® membrane degradation , 2007 .