Journal of the Korean Electrochemical Society (전기화학회지)

The Korean Electrochemical Society (한국전기화학회)
권호 표지
DOI QR코드

DOI QR Code

Surface Modification of Nafion by Layer-by-Layer Self-Assembled Films of Polyaniline and Sulfonated Poly(ether sulfone) for Direct Methanol Fuel Cell

직접 메탄올 연료전지용 나피온 막의 폴리아닐린/Sulfonated Poly(ether sulfone) 다층 자기조립 박막에 의한 표면 개질

  • Ok, Jeong-Rim (Advanced Materials Division, Korea Research Institute of Chemical Technology) ;
  • Kim, Dong-Wook (Advanced Materials Division, Korea Research Institute of Chemical Technology) ;
  • Lee, Chang-Jin (Advanced Materials Division, Korea Research Institute of Chemical Technology) ;
  • Kang, Yong-Ku (Advanced Materials Division, Korea Research Institute of Chemical Technology)
  • 옥정림 (한국화학연구원 화학소재연구단) ;
  • 김동욱 (한국화학연구원 화학소재연구단) ;
  • 이창진 (한국화학연구원 화학소재연구단) ;
  • 강영구 (한국화학연구원 화학소재연구단)
  • Published : 2008.11.30
Download PDF
⟨ Previous Next ⟩

Abstract

In this study, Nafion membrane was modified to prevent methanol crossover by layer-by-layer self assembly using polyaniline (PANi) as a polycation and sulfonated poly(ether sulfone) (SPES) as a polyanion onto the Nafion surface. Since PANi and SPES possess thermal and chemical stability and rigid backbone, their layer-by-layer self-assembled films on the Nafion are expected to reduce methanol permeability and to increase mechanical stability. UV-Vis absorption spectroscopy verified a linear build-up of the multilayers of PANi and SPES. We found that the thickness per bilayer was about 10 nm by TEM measurement. Although modified Nafion membrane exhibited 15% decrease of proton conductivity, it reduceded 67% of methanol permeability compared to that of the pristine Nafion membrane, resulting in 2.5 times larger selectivity. At the performance test of the fuel cell using 5M methanol as a fuel, the modified Nafion membrane showed 2.4 times higher maximum power density at $30^{\circ}C$ and 1.4 times larger at $60^{\circ}C$ than the pristine Nafion.

본 연구에서는 나피온 막을 통한 메탄올 투과도를 감소시키기 위하여 양전하를 띠는 polyaniline(PANi)와 음전하를 갖는 sulfonated Poly(ether sulfone)(SPES)으로부터 다층 자기조립 박막법으로 나피온 막의 표면을 개질하였다. PANi과 SPES는 열적 화학적으로 안정하며 매우 강직한 특성을 띄고 있어, 나피온 막 표면에 다층 자기조립 박막 형성시 메탄올 투과도 감소 및 치수 안정성의 향상을 기대할 수 있다. 자외선-가시광선 흡광분석에 의하여 PANi와 SPES의 다층박막의 형성이 균일하게 이루어짐을 확인 하였다. TEM 분석을 통하여 다층 자기조립 박막의 bilayer당 두께가 약 10 nm 정도임을 확인 하였다. 개질된 나피온 막은 순수한 나피온 막에 비하여 15%의 이온전도도 감소가 일어났지만 67%의 높은 메탄올 투과도 감소를 나타내어 2.5배 높은 선택도를 보였다. 5 M 메탄올을 연료로 사용한 연료전지 성능시험에서 개질된 나피온 막은 순수한 나피온 막에 비해 최대 전력 밀도가 $30^{\circ}C$에서는 2.4배 증가, $60^{\circ}C$에서는 1.4배 향상을 나타내었다.

Keywords

References

  1. M. Rikuawa and K. Sanui, 'Proton-Conducting Polymer Electrolyte Membranes Based on Hydrocarbon Polymers' Prog. Polym. Sci., 25, 1463 (2007) https://doi.org/10.1016/S0079-6700(00)00032-0
  2. J. A. Kerres, 'Development of Ionomer Membranes for Fuel Cell' J. Membr. Sci., 185, 3 (2001) https://doi.org/10.1016/S0376-7388(00)00631-1
  3. S. R. Narayanan, T. L. Valdez, and N. Rohatgi in "Handbook of Fuel Cells", Eds. By W. Vielstich, A. Lamm, and H.A. Gasteiger, John Wiley & Sons, West Sussex, 3, 894 (2003)
  4. V. Tricoli, 'Proton and Methanol Transport in Poly (perfluoro -sulfonate) Membranes Containing Cs+ and H+ Cations' J. Electrochem. Soc., 145, 3798 (1998) https://doi.org/10.1149/1.1838876
  5. C. Manea and M. Mulder, 'Characterization of Polymer Blends of Polyethersulfone/Sulfonated Polysulfone and Polyethersulfone/sulfonated Polyetheretherketone For Direct Methanol Fuel Cell Applications' J. Membr. Sci., 206, 443 (2003) https://doi.org/10.1016/S0376-7388(01)00787-6
  6. L. Li, J. Zhang, and Y. Wang, 'Sulfonated Poly(ether ether ketone) Membranes for Direct Methanol Fuel Cell' J. Membr. Sci., 226, 159 (2003) https://doi.org/10.1016/j.memsci.2003.08.018
  7. D. J. Jones and J. Roziere,v 'Recent advAnces in The Functionalization of Polybenzimidazole and Polyetherketone For Fuel Cell Applications' J. Membr. Sci., 185, 41 (2001) https://doi.org/10.1016/S0376-7388(00)00633-5
  8. B. smitha, S. Sridhar, and A. A. Khan, 'Synthesis and Characterization of Proton Conducting Polymer Membranes For Fuel Cells' J. Membr. Sci., 225, 63 (2003) https://doi.org/10.1016/S0376-7388(03)00343-0
  9. K. M. Nouel and P. S. Fedkiw, 'Nafion-based Composite Polymer Electrolyte Membranes' Electrochim. Acta, 43, 2381 (1998) https://doi.org/10.1016/S0013-4686(97)10151-7
  10. S. Tan and D. Blanger, 'Characterization and Transport Properties of Nafion/Polyaniline Composite Membranes' J. Phys. Chem. B, 109, 23480 (2005) https://doi.org/10.1021/jp054724e
  11. F. Zhang, N. Li, Z. Cui, S. Zhang, and S. Li, 'Novel Acid-base Polyimides Synthesized From Binaphthalene Dianhydride and Triphenylamine-containing Diamine As Proton Exchange Membranes' J. Membr. Sci., 314, 24 (2008) https://doi.org/10.1016/j.memsci.2008.01.032
  12. J. L. Casson, D. W. McBranch, J. M. Robinson, H. L. Wang, J. B. Roberts, P. A. Chiarelli, and M. S. Johal, 'Reversal of Interfacial Dipole Orientation in Polyelectrolyte Superlattices Due to Polycationic Layers' J. Phys. Chem. B, 104, 11996 (2000) https://doi.org/10.1021/jp0029616
  13. D. W. Kim, A. Blumstein, J. Kumar, L. A. Samuelson, B. Kang, and C. Sung, 'Ordered Multilayer Nanocomposites Prepared by Electrostatic Layer-by-Layer Assembly between Aluminosilicate Nanoplatelets and Substituted Ionic Polyacetylenes' Chem. Mater., 14, 3925 (2002) https://doi.org/10.1021/cm0203823
  14. D. W. Kim, J. Kumar, and A. Blumstein, 'Ordered Assembly of Conjugated Ionic Polyacetylenes Within Clay Nanoplatelets: Layer-by-layer Assembly and Intercalative Polymerization' Appl. Clay Sci., 30, 134 (2005) https://doi.org/10.1016/j.clay.2005.04.005
  15. D. W. Kim, B. C. Ku, D. Steeves, R. Nagarajan, A. Blumstein, J. Kumar, P. W. Gibson, J. A. Ratto, and L. A. Samuelson, 'Hydrophobic Barrier: Molecular Selfassembly of Amphiphilic Polyacetylenes Within Aluminosilicate Nanoplatelets' J. Membr. Sci., 275, 12 (2006) https://doi.org/10.1016/j.memsci.2005.08.021
  16. D. W. Kim, H. S. Choi, C. Lee, A. Blumstein, and Y. Kang, 'Investigation on Methanol Permeability of Nafion Modified by Self-assembled Clay-nanocomposite Multilayers' Electrochimica Acta, 50, 659 (2004) https://doi.org/10.1016/j.electacta.2004.01.125
  17. J. Ok, D. W. Kim, C. Lee, W.C. Choi, S. Cho, and Y. Kang, 'Methanol Barriers Derived from Layer-by-Layer Assembly of Poly(ethersulfone)s for High Performance Direct Methanol Fuel Cells' Bull. Korean Chem. Soc., 29, 842 (2008) https://doi.org/10.5012/bkcs.2008.29.4.842
  18. J. H. Cheung, W. B. Stockton, and M. F. Rubner, 'Molecular- Level Processing of Conjugated Polymer. 3. Layer-by-Layer Manipulation of Polyaniline via Electrostatic Interaction' Macromolecules, 30, 2712, (1997) https://doi.org/10.1021/ma970047d
  19. W. B. Stockton, and M. F. Rubner, 'Molecular-Level Processing of Conjugated Polymer. 4. Layer-by-Layer Manipulation of Polyaniline via Hydrogen-Bonding Interaction' Macromolecules, 30, 2717 (1997) https://doi.org/10.1021/ma9700486
  20. F. Xie, C. Chen, H. Meng, and P. K. Shen, 'Effect of the Anodic Diffusion Layer on the Performance of Liquid Fuel Cells' Fuel Cells, 7, 319 (2007) https://doi.org/10.1002/fuce.200600043
  21. M. S. Wilson, and S. Gottesfeld, 'Thin-film Catalyst Layers for Polymer Electrolyte Fuel Cell Electrodes' J. Appl. Electrochem., 22, 1 (1992) https://doi.org/10.1007/BF01093004
  22. Q. Ye, T, and S. ZhaO, 'A Natural-circulation Fuel Delivery System for Direct Methanol Fuel Cells' J. Power Sources, 147, 196, (2005) https://doi.org/10.1016/j.jpowsour.2005.01.026