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Yamaki, Tetsuya; Sawada, Shinichi; Asano, Masaharu; Maekawa, Yasunari; Yoshida, Masaru*; Gubler, L.*; Alkan G
rsel, S.*; Scherer, G. G.*
ECS Transactions, 25(1), p.1439 - 1450, 2009/10
Times Cited Count：4 Percentile：83.35(Electrochemistry)A multiply-crosslinked polymer electrolyte membrane was prepared by the radiation-induced co-grafting of styrene and a bis(vinyl phenyl)ethane (BVPE) crosslinker into a radiation-crosslinked polytetrafluoroethylene (cPTFE) film. We then investigated its hydrogen/oxygen fuel-cell performance at 60 and 80
C in terms of the effect of radiation and chemical crosslinking. At 60C, all the membranes initially exhibited similar performance, but only the cPTFE-based membranes were durable at 80C, indicating the necessity of radiation crosslinking in the PTFE main chains. Importantly, cell performance of the multiply-crosslinked membrane was found high enough to reach that of a Nafion112 membrane. This is probably because the BVPE crosslinks in the graft component improved the membrane-electrode interface in addition to membrane durability. After severe OCV hold tests at 80 and 95C, the performance deteriorated, while no significant change was observed in ohmic resistivity. Accordingly, our membranes seemed so chemically stable that an influence on overall performance loss could be negligible.
Ben youcef, H.*; Gubler, L.*; Yamaki, Tetsuya; Sawada, Shinichi; Alkan Grsel, S.*; Wokaun, A.*; Scherer, G. G.*
Journal of the Electrochemical Society, 156(4), p.B532 - B539, 2009/02
Times Cited Count：16 Percentile：50.78(Electrochemistry)The effect of cross-linker content on the chemical stability of poly(ethylene-
-tetrafluoroethylene) (ETFE)-based radiation-grafted and sulfonated membranes was investigated. An ex situ degradation test in hydrogen peroxide solution showed a strong increase in stability of crosslinked membranes compared to uncrosslinked ones. Excessive crosslinking, however, is detrimental to the chemical and mechanical properties. Furthermore, the stability of grafted membranes based on ETFE was superior to those based on poly(tetrafluoroethylene-
-hexafluoropropylene) (FEP). An in situ long-term test in a hydrogen/oxygen single cell over 2180 h, using an ETFE-based grafted membrane optimized with respect to cross-linker content, with a graft level of 25% was carried out. The performance of the membrane electrode assembly exhibited a voltage decay rate of 13 
V/h over the testing time at a current density of 500 mA/cm
and a cell temperature of 80C, while the hydrogen permeation showed a steady increase over time. This indicates that, to some extent, changes in the membrane morphology occur over the operating period. Local postmortem analysis of the tested membrane reveals that high degradation was observed in areas adjacent to the oxygen inlet and in other areas nearby.
Yamaki, Tetsuya; Sawada, Shinichi; Asano, Masaharu; Maekawa, Yasunari; Yoshida, Masaru; Gubler, L.*; Guersel, S. A.*; Scherer, G.*
no journal, ,
Multiply-crosslinked polymer electrolyte membranes were prepared by radiation-induced co-grafting of styrene and a bis(vinyl phenyl)ethane (BVPE) crosslinker into radiation-crosslinked polytetrafluoroethylene (cPTFE) films. We then investigated their hydrogen-oxygen PEFC performance at 60 and 80C in terms of the effect of radiation and chemical crosslinking. At 60C, all the membranes initially exhibited similar performance, but only the cPTFE-based membranes were durable at 80C, indicating necessity of radiation crosslinking in the PTFE main chains. Importantly, cell performance of the multiply-crosslinked membranes was found high enough to reach that of Nafion112. This is probably because the BVPE crosslinks in graft components improved the membrane-electrode interface in addition to membrane durability. After severe OCV hold tests at 80 and 95C, the performance deteriorated, while no significant change was observed in ohmic resistivity. Accordingly, our membranes seemed so stable that they could not have any serious influence on overall performance.
Yamaki, Tetsuya; Sawada, Shinichi; Asano, Masaharu; Maekawa, Yasunari; Yoshida, Masaru; Gubler, L.*; Alkan Grsel, S.*; Scherer, G.*
no journal, ,
Multiply-crosslinked polymer electrolyte membranes were prepared by radiation-induced co-grafting of styrene and a bis(vinyl phenyl)ethane (BVPE) crosslinker into radiation-crosslinked polytetrafluoroethylene (cPTFE) films. We then investigated their PEFC performance in terms of the effect of radiation and chemical crosslinking. Importantly, cell performance of the multiply-crosslinked membranes was found high enough to reach that of Nafion112. This is probably because the BVPE crosslinks in graft components improved the membrane-electrode interface in addition to membrane durability. After severe open circuit voltage hold tests, the performance deteriorated, while no significant change was observed in ohmic resistivity. Accordingly, our membranes seemed so stable that they could not have any serious influence on overall performance.
