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Solid-state polymer electrolyte membranes (PEMs) exhibiting high ionic conductivity coupled with mechanical robustness and high thermal stability are vital for the design of next-generation lithium-ion batteries and high-temperature fuel cells. We present the in situ preparation of nanostructured PEMs incorporating a protic ionic liquid (IL) into one of the domains of a microphase-separated block copolymer created via polymerization-induced microphase separation. This facile, one-pot synthetic strategy transforms a homogeneous liquid precursor consisting of a poly(ethylene oxide) (PEO) macro-chain-transfer agent, styrene and divinylbenzene monomers, and protic IL into a robust and transparent monolith. The resulting PEMs exhibit a bicontinuous morphology comprising PEO/protic IL conducting pathways and highly cross-linked polystyrene (PS) domains. The cross-linked PS mechanical scaffold imparts thermal and mechanical stability to the PEMs, with an elastic modulus approaching 10 MPa at 180 °C, without sacrificing the ionic conductivity of the system. Crucially, the long-range continuity of the PEO/protic IL conducting nanochannels results in an outstanding ionic conductivity of 14 mS/cm at 180°C. We posit that proton conduction in the protic IL occurs via the vehicular mechanism and the PEMs exhibit an average proton transference number of 0.7. This approach is very promising for the development of high-temperature, robust PEMs with excellent proton conductivities.
Bibliographical noteFunding Information:
This work was supported by the National Science Foundation (Grants DMR-1006370 and DMR-1206459). SAXS data were obtained at the APS, Sector 5 (DuPont?Northwestern?Dow Collaborative Access Team, DND-CAT) and Sector 12. DNDCAT is supported by The Dow Chemical Company, E. I. DuPont de Nemours & Co., and Northwestern University. Use of the APS, an Office of Science User Facility operated for the U.S. Department of Energy (DOE), Office of Science, by Argonne National Laboratory, was supported by the U.S. DOE under Contract DE-AC02-06CH11357. Portions of this work were carried out in the Characterization Facility, University of Minnesota, which receives partial support from the NSF through the MRSEC program (Grant DMR-1420013). The authors thank Prof. Philippe B?hlmann for access to his impedance spectroscopy equipment and Dr. Lucas McIntosh, Morgan Schulze, and Matthew Irwin for helpful discussions.
© 2016 American Chemical Society.
- bicontinuous morphology and high-temperature fuel cells
- polymer electrolyte membranes
- polymerization-induced microphase separation
- protic ionic liquids
How much support was provided by MRSEC?
Reporting period for MRSEC
- Period 3
PubMed: MeSH publication types
- Journal Article
- Research Support, Non-U.S. Gov't
- Research Support, U.S. Gov't, Non-P.H.S.