Atomistic and molecular simulations of novel acid-base blend membranes for direct methanol fuel cells

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dc.contributor.advisorGanesan, Venkat
dc.creatorMahajan, Chetan Vasanten
dc.date.accessioned2014-02-04T15:36:54Zen
dc.date.accessioned2017-05-11T22:41:28Z
dc.date.available2017-05-11T22:41:28Z
dc.date.issued2013-08en
dc.date.submittedAugust 2013en
dc.date.updated2014-02-04T15:36:55Zen
dc.descriptiontexten
dc.description.abstractOne of the main challenges to transform highly useful Direct Methanol Fuel Cells (DMFC) into a commercially viable technology has been to develop a low cost polymer electrolyte membrane (PEM) with high proton conductivity, high stability and low methanol crossover under operating conditions desirably including high temperatures. Nafion, the widely used PEM, fails to meet all of these criteria simultaneously. Recently developed acid-base polymer blend membranes constitute a promising class of PEMs alternative to Nafion on above criteria. Even though some of these membranes produce better performance than Nafion, they still present numerous opportunities for maximizing high temperature proton conductivity and dimensional stability with concomitant minimization of methanol crossover. Our contribution embarks on the fundamental study of one such novel class of blend membranes viz., sulfonated poly (ether ether ketone) (SPEEK)(95 % by weight) blended with polysulfone tethered with base (5 % by weight) such as 2-aminobenzimidazole (ABIm), 5-amino-benzotriazole (BTraz) and 1H-perimidine (PImd), developed by Manthiram group at The University of Texas at Austin. In this work, we report extensive all-atom classical as well as ab-initio molecular dynamics (MD) simulations of such water-methanol solvated blend membranes (as well as pure SPEEK and Nafion) the first time. Our approach consists of three steps: (1) Predict dynamical properties such as diffusivities of water, methanol and proton in such membranes (2) Validate against experiments (3) Develop understanding on the interplay between basic chemistry, structure and properties, the knowledge that can potentially be used to develop better candidate membranes. In particular, we elucidate the impact of simple, fundamental physiochemical features of the polymeric membranes such as hydrophilicity, hydrophobicity, structure or the size of the base on the structural manifestations on the bigger scale such as nanophase segregation, hydrogen bonding or pore sizes, which ultimately affect the permeant transport through such systems.en
dc.description.departmentChemical Engineeringen
dc.format.mimetypeapplication/pdfen
dc.identifier.urihttp://hdl.handle.net/2152/23030en
dc.language.isoen_USen
dc.subjectMethanol fuel-cellsen
dc.subjectMolecular-dynamics simulationen
dc.subjectPolymer electrolyte membranesen
dc.subjectForce-fielden
dc.subjectPolymer membranesen
dc.subjectHydrated nafionen
dc.subjectFuel-cell applicationsen
dc.subjectProton-exchange membranesen
dc.subjectNanophase-segregationen
dc.subjectAtomistic simulationsen
dc.subjectAb initio molecular dynamics simulationsen
dc.subjectProton hoppingen
dc.subjectZundel ionsen
dc.subjectImmidazoliumen
dc.subjectResonance stabilizationen
dc.subjectSulfonated poly(ether ether ketone)en
dc.subjectPolysulfoneen
dc.subjectBenzotriazoleen
dc.subjectBenzimidazoleen
dc.subjectPerimidineen
dc.titleAtomistic and molecular simulations of novel acid-base blend membranes for direct methanol fuel cellsen

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