On the incorporation of protic ionic liquids imbibed in large pore zeolites to polybenzimidazole membranes for high temperature proton exchange membrane fuel cells

Conducting fillers based on 2-hydromethyl) trimethylammoniun dimethyl phosphate (IL1), N,N-dimethyl-N-(2-hydroxyethyl) ammonium bis(trifluoromethanesulfonyl)imide (IL2) and 1-H-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (IL3) encapsulated in large pore zeolites (NH4BEA and NaY) have been...

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Bibliographic Details
Published in:Journal of power sources 2013-01, Vol.222, p.483-492
Main Authors: Eguizábal, A., Lemus, J., Pina, M.P.
Format: Article
Language:English
Subjects:
Applied sciences
Assisted proton transport
Dimethyl
Direct energy conversion and energy accumulation
Electrical engineering. Electrical power engineering
Electrical power engineering
Electrochemical conversion: primary and secondary batteries, fuel cells
Electrolytes
Energy
Energy. Thermal use of fuels
Equipments for energy generation and conversion: thermal, electrical, mechanical energy, etc
Exact sciences and technology
Fillers
Fuel cells
H2/O2 single cell performance
High temperature applications
Hybrid polybenzimidazole membranes
Ionic liquids
Large pore zeolites
Materials
Optimization
Polybenzimidazoles
Porosity
Proton exchange membrane fuel cells
Zeolites
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Summary:Conducting fillers based on 2-hydromethyl) trimethylammoniun dimethyl phosphate (IL1), N,N-dimethyl-N-(2-hydroxyethyl) ammonium bis(trifluoromethanesulfonyl)imide (IL2) and 1-H-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (IL3) encapsulated in large pore zeolites (NH4BEA and NaY) have been added to the PBI casting solution for the preparation of high temperature proton exchange membranes (HTPEMs). The filler loading has been systematically varied from 3% to 20% wt. for all the studied composites. The morphological, physicochemical, and electrochemical properties of the as prepared hybrid doped PBI membranes have been fully characterized. For a given conduction filler, the optimum loading is found to be 3% wt. as inferred from the conductivity measurements at 0.05 water molar fraction. Among the tested, the outstanding electrolyte membranes are those containing IL3-NaY. The exhibited through-plane proton conductivity is 54 mS cm−1 at 200 °C for the optimum PBI + IL3-NaY_3%wt hybrid membrane. The so obtained results are explained by the assisted 1-H-3-methylimidazolium and bis(trifluoromethanesulfonyl)imide hydrogen bonding type interactions, clearly beneficial for the proton conduction processes. Moreover, the H2 permeability values for the hybrid electrolyte membranes and pure PBI are quite similar at the examined conditions; indicating the suitability of the preparation procedure in terms of fuel cross-over. The H+/H2 transport selectivity of the optimum IL3-NaY composite membrane clearly outperforms pure PBI and zeolite-PBI counterparts at 50°, 100° and 150 °C. Finally, the optimum composite membranes have been validated in H2/O2 single cell under non humidified conditions up to 180 °C as a “proof of concept” demonstration. ► Synergic combination between H3PO4, PBI and IL3 imbibed in NaY. ► IL3 molecules leached out from NaY crystals contribute to the conduction outperformance. ► H+/H2 transport selectivity values higher than PBI and hybrid NaY–PBI counterparts. ► Proof of concept demonstration in H2/O2 single cell up to 180 °C under non humidified conditions. ► I–V improvement performance values over pristine PBI ranging from 20% up to 100%.
ISSN:0378-7753
1873-2755
DOI:10.1016/j.jpowsour.2012.07.094