Impedance of vapor feed direct methanol fuel cells-polarization dependence of elementary processes at the anode

被引:37
作者
Fukunaga, H [1 ]
Ishida, T [1 ]
Teranishi, N [1 ]
Arai, C [1 ]
Yamada, K [1 ]
机构
[1] Shinshu Univ, Fac Text Sci & Technol, Dept Fine Mat Engn, Ueda, Nagano 3868567, Japan
关键词
direct methanol fuel cell; vapor feed; ac impedance spectroscopy; rate-determining step; interfacial conductivity;
D O I
10.1016/j.electacta.2003.12.037
中图分类号
O646 [电化学、电解、磁化学];
学科分类号
081704 ;
摘要
Membrane electrode assemblies of direct methanol fuel cells (DMFCs) with different catalyst and ionomer loading were prepared. Anode performance and impedance spectra were measured to clarify the characteristics of vapor feed DMFCs (VF-DMFCs). The impedance spectra were deconvolved into three semi-circles with different time constants, each showing a different dependence on the anodic polarization. The middle-frequency range arc decreased as the anodic polarization increased, indicating that this process represents the oxidation reaction of methanol. The high-frequency range arc showed little dependence on the anodic polarization, but increased with the thickness of the electrode, indicating that this process might be related to proton conduction through the electrode. The low-frequency range are was observed only when the methanol concentration was low, in contrast to liquid feed DMFCs (LF-DMFCs), for which the removal of the product gas presents a large resistance. A simpler design can therefore be used for a VF-DMFC, giving it an advantage over an LF-DMFC. A decreasing ionomer to catalyst ratio (I/C) caused the interfacial conductivity (sigma(E)) to increase, but it intensively decreased when I/C was below 0.25. Thus, the connection of the catalysts is important for the anode's performance. (C) 2004 Elsevier Ltd. All fights reserved.
引用
收藏
页码:2123 / 2129
页数:7
相关论文
共 20 条
[1]   The effect of anode flow characteristics and temperature on the performance of a direct methanol fuel cell [J].
Amphlett, JC ;
Peppley, BA ;
Halliop, E ;
Sadiq, A .
JOURNAL OF POWER SOURCES, 2001, 96 (01) :204-213
[2]   Carbon dioxide evolution patterns in direct methanol fuel cells [J].
Argyropoulos, P ;
Scott, K ;
Taama, WM .
ELECTROCHIMICA ACTA, 1999, 44 (20) :3575-3584
[3]  
Boukamp B., 1989, EQUIVALENT CIRCUIT U
[4]   Anodic reaction of vapor feed direct methanol fuel cell [J].
Fukunaga, H ;
Teranishi, N ;
Yamada, K .
KAGAKU KOGAKU RONBUNSHU, 2003, 29 (02) :179-183
[5]   Mechanism and electrocatalysis in the direct methanol fuel cell [J].
Hamnett, A .
CATALYSIS TODAY, 1997, 38 (04) :445-457
[6]   The design and construction of high-performance direct methanol fuel cells. 2. Vapour-feed systems [J].
Hogarth, M ;
Christensen, P ;
Hamnett, A ;
Shukla, A .
JOURNAL OF POWER SOURCES, 1997, 69 (1-2) :125-136
[7]   The design and construction of high-performance direct methanol fuel cells. 1. Liquid-feed systems [J].
Hogarth, M ;
Christensen, P ;
Hamnett, A ;
Shukla, A .
JOURNAL OF POWER SOURCES, 1997, 69 (1-2) :113-124
[8]   DISTINCT PERFORMANCE EVALUATION OF A DIRECT METHANOL SPE FUEL-CELL - A NEW METHOD USING A DYNAMIC HYDROGEN J-REFERENCE ELECTRODE [J].
KUVER, A ;
VOGEL, I ;
VIELSTICH, W .
JOURNAL OF POWER SOURCES, 1994, 52 (01) :77-80
[9]   Recent advances in the development of direct alcohol fuel cells (DAFC) [J].
Lamy, C ;
Lima, A ;
LeRhun, V ;
Delime, F ;
Coutanceau, C ;
Léger, JM .
JOURNAL OF POWER SOURCES, 2002, 105 (02) :283-296
[10]   Characterization of direct methanol fuel cells by AC impedance spectroscopy [J].
Mueller, JT ;
Urban, PM .
JOURNAL OF POWER SOURCES, 1998, 75 (01) :139-143