About the Choice of the Protogenic Group in PEM Separator Materials for Intermediate Temperature, Low Humidity Operation: A Critical Comparison of Sulfonic Acid, Phosphonic Acid and Imidazole Functionalized Model Compounds

Fuel Cells - Tập 5 Số 3 - Trang 355-365 - 2005
M. Schuster1, Timo Rager1, Akihiro Noda1, Klaus‐Dieter Kreuer1, Joachim Maier1
1Max-Planck-Institut für Festkörperforschung, Heisenbergstr. 1, D-70569 Stuttgart, Germany

Tóm tắt

AbstractTraditionally, sulfonated polymers are used as separator materials in PEM fuel cells. Based on recent experimental results on model compounds this paper critically discusses the potentials and limits of sulfonic acid and alternatively phosphonic acid and heterocycles (imidazole) as protogenic groups for PEM fuel cell electrolytes operating at intermediate temperatures (T > 100 °C) and low humidification. Apart from transport properties, the stability and reactivity of mono‐functionalized model compounds (1‐heptylsulfonic acid (S‐C7), 1‐heptylphosphonic acid (P‐C7) and 2‐heptyl‐imidazole (I‐C7)) and a few diphosphonic acids are examined under wet and dry conditions. These are characterized with respect to their proton conductivity (ac impedance spectroscopy), proton diffusion coefficient (pulsed‐field gradient NMR), thermo‐oxidative stability (TGA under air), electrochemical stability (cyclic voltammetry) and their hydration behavior (TGA under water vapor). The sulfonic acid functionalized compound shows reasonable properties only when a minimum hydration level is guaranteed, while phosphonic acid functionalized compounds combine satisfactory proton conductivity even in the water‐free state at intermediate temperatures (T < 200 °C), comparatively high thermo‐oxidative and electrochemical stability and electrochemical reactivity (hydrogen oxidation and oxygen reduction at platinum surfaces). The presence of water leads to moderate water uptake allowing for reasonable conductivities even at room temperature and prevents condensation reactions at higher temperature. The imidazole based system shows the largest electrochemical stability window, but its moderate proton conductivity and thermo‐oxidative stability and the very high overpotential for oxygen reduction on platinum turn out to be severe disadvantages for the envisaged application.

Từ khóa


Tài liệu tham khảo

Kreuer K. D., 1995, Proc. Electrochem. Soc., 241

10.1016/S0167-2738(97)00082-9

10.1016/0009-2614(95)00905-J

10.1063/1.469654

10.1126/science.275.5301.817

10.1002/anie.198202082

10.1021/cm950192a

10.1016/S0376-7388(00)00632-3

10.1021/cr020715f

10.1002/1439-7641(20020916)3:9<771::AID-CPHC771>3.0.CO;2-Y

10.1016/0013-4686(94)85176-X

10.1016/j.electacta.2003.12.004

K. D. Kreuer inHandbook of Fuel Cells – Fundamentals Technology and Applications Vol. 3(Eds. W. Vielstich A. Lamm H. A. Gasteiger) John WILEY & Sons 2003.

M. Schuster K. D. Kreuer J. Maier presented at SSPC‐11 (Surrey Guildford UK) 2002.

10.1016/S0013-4686(97)10031-7

K. D. Kreuer inSolid State Ionics: Science & Technology (Eds. B. V. R. Chowdari et al.) World Scientific Publishing Co. 1998 pp. 263.

10.1016/S0167-2738(01)00941-9

10.1016/S0167-2738(01)00917-1

10.1016/S0013-4686(03)00200-7

10.1146/annurev.matsci.33.022702.155349

10.1016/S0167-2738(00)00301-5

G. Scharfenberger PhD thesis University of Mainz 2003.

Unpublished results from the authors laboratory.

10.1021/jp022347p

10.1016/S0378-7753(01)00812-6

10.1016/S0376-7388(00)00632-3

Xu X., 1993, Polym. Mater. Sci. Eng., 68, 120

10.1016/S0022-1139(96)03534-8

Stone C., 2000, J. New Mater. Electrochem. Syst., 3, 43

10.1016/S0014-3057(99)00158-5

10.1002/pola.1304

10.1002/pola.10032

10.1021/ma010258p

10.1016/S0376-7388(01)00702-5

10.1016/S0167-2738(02)00449-6

10.1016/S0167-577X(01)00391-3

10.1021/ma0116295

10.1002/macp.200290066

10.1016/S0014-3057(02)00238-0

10.1016/S0379-6779(02)00542-8

10.1016/0022-1902(61)80447-8

10.1063/1.1695690

Th. Dippel K. D. Kreuer M. Hampele A. Rabenau in25thCongress Ampere (Eds. M. Mehring J. U. von Schütz H. C. Wolf) Springer 1990.

10.1039/tf9696500585

10.1021/je60022a041

10.1139/v53-044

10.1021/je00013a016

10.1016/S0167-2738(97)00034-9

10.1006/jssc.1999.8495

10.1016/0167-2738(93)90332-W

10.1039/b209415k

10.1149/1.1837104

10.1149/1.2127232

10.1021/j100894a031

10.1149/1.2127231

10.1016/0022-0728(88)87028-1

10.1149/1.2059334

10.1149/1.2059335

10.1146/annurev.matsci.33.022702.154702

10.1016/S0376-7388(00)00635-9

S. Paddison K. D. Kreuer J. Maier . in preparation.

H. Rößler M. Schuster K. D. Kreuer J. Maier presented at SSPC‐12 (Uppsala Sweden) 2004.

Thông tin
Thông tin xuất bản

Fuel Cells

Tập 5 Số 3

355-365

Thông tin tác giả