High proton conducting SPEEK/SiO₂/PWA composite membranes for direct methanol fuel cells

Abstract

Sulfonated polyether ether ketone (SPEEK) based composite membranes for direct methanol fuel cell (DMFC) application were prepared by sol-gel reaction of tetraethoxysilane (TEOS) in the SPEEK matrix and the incorporation of phosphotungstic acid (PWA). The conductivity of the developed membranes was determined by impedance spectroscopy and the methanol permeability through the membranes was obtained from diffuseness experiments. The SEM images show that the addition of SiO₂ and the covalent cross-linking structure lead to fine PWA particles and more uniformly dispersion. The swelling of composite membranes remains in the range of 5%–8% at 30–90 °C and the effusion of PWA reduces significantly. The composite membranes show a good balance in higher proton conductivity and lower methanol permeation. The cell with composite membrane has higher open circuit voltage(0.728 V) and higher peak power density(45 mW/cm²) than that with Nafion117.

Keywords

direct methanol fuel cell / sulfonated polyether ether ketone / sol-gel method / PWA / SiO₂

References

[1] Carrette L., Friedrich K. A., Stimming U. Fuel Cell Fundamentals and Applications[J]. Fuel cells, 2001, 1: 5-39.

[2] Kerres J. A. Development of Ionomer Membranes for Fuel Cells[J]. J. Membr. Sci., 2001, 185: 3-27.

[3] Woo Y. Synthesis and Characterization of Sulfonated Polyimide Membranes for Direct Methanol Fuel Cell[J]. J. Membr. Sci., 2003, 220: 31-45.

[4] Poppe D., Frey H., Kreuer K. D., . Carboxylated and Sulfonated Poly(arylene-co-arylene sulfone)s: Thermostable Polyelectrolytes for Fuel Cell Applications[J]. Macromolecules, 2002, 35: 7 936-7 941.

[5] Li L., Zhang J., Wang Y. X. Sulfonated Poly(ether ether ketone) Membranes for Direct Methanol Fuel Cell[J]. J. Membr. Sci., 2003, 226: 159-167.

[6] Xing P., Robertson G. P., Guive M. D., . Synthesis and Characterization of Sulfonated Poly(ether ether ketone) for Proton Exchange Membranes[J]. J. Membr. Sci., 2004, 229: 95-106.

[7] Kreuer K. D. On the Development of Proton Conducting Polymer Membranes for Hydrogen and Methanol Fuel Cells[J]. J. Membr. Sci., 2001, 185: 29-39.

[8] Mikhailenko S. D., Wang K., Kaliaguine S., . Proton Conducting Membranes Based on Cross-linked Sulfonated Poly(ether ether ketone) (SPEEK) [J]. J. Membr. Sci., 2004, 233: 93-99.

[9] S S Mao, S J Hamrock, D A Ylitalo. Crosslinked Ion Conductive Membranes[P]. US Patent 6,090,895 (2000)

[10] Nunes S. P., ruffmann B., Rikowski E., . Inorganic Modification of Proton Conductive Polymer Membranes for Direct Methanol Fuel Cells[J]. J. Membr. Sci., 2002, 203: 215-225.

[11] Zhang G., Zhou Z., Li C. Proton Conducting Composite Membranes from Sulfonated Polyether Ether Ketone and SiO₂[J]. J. Wuhan University of Technology-Mater. Sci. Ed., 2009, 1: 24-28.

[12] Zhang G., Zhou Z. Organic/Inorganic Composite Membranes for Application in DMFC[J]. J. Membr. Sci., 2005, 261: 107-113.

[13] Ramani V., Kunz H. R., Fenton J. M. Investigation of Nafion ®/HPA Composite Membranes for Hightemperature/Low Relative Humidity PEMFC Operation[J]. J. Membr. Sci., 2004, 232: 31-44.