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Atomistic investigation of polymer electrolyte membrane nanostructure and dynamics of molecular transport in fuel cells

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dc.contributor.author Sunda, Anurag Prakash
dc.date.accessioned 2014-05-08T06:46:46Z
dc.date.available 2014-05-08T06:46:46Z
dc.date.issued 2014-05-08
dc.identifier.uri http://idl.iiserpune.ac.in:8080/jspui/handle/123456789/370
dc.description Author has taken copyright permissions to include graphs from copyrighted articles of American Chemical Society, American Physical Society, John Wiley & Sons, Elsevier Science Ltd., Macmillan Publisher Ltd., Royal Society of Chemistry, Taylor & Francis and National Academy of Sciences, USA and referred accordingly. en_US
dc.description.abstract In Polymer Electrolyte Membrane (PEM) fuel cells, the PEM is sandwiched between the electrodes to facilitate the proton transport from anode to cathode. A molecular study of structural and dynamical properties of various PEMs from simulations can facilitate the development of aqueous/non-aqueous PEMs for fuel cell applications. In this thesis, polymer membranes like the aliphatic Perfluorosulfonic acid (PFSA) membranes [for example: Nafion (Dupont), Aciplex (Asahi Chemicals Co.) and Dow (Dow Chemicals)] and hetero aromatic benzimidazole based membranes (ABPBI) are chosen for investigation using Molecular Dynamics (MD) simulations. A characterization of ammonium based ionic liquids (ILs) using MD simulations and experimental techniques is also presented in this thesis. MD simulations on trifluoromethanesulfonic (triflic) acid and triflate ion-water mixtures are performed to mimic the functional group of hydrated PFSA polymer electrolyte membranes where the sulfonate group is responsible for proton conduction. Subsequently, a comparative study of pendant-water mixtures of Dow, Aciplex and Nafion membranes is performed to investigate the role of the ether oxygen in side chain and the side chain length. The nanostructure of the full Aciplex ionomer membrane and dynamics of hydronium ions and water molecules is also investigated. A molecular investigation of the hydrated ABPBI polymer membrane doped with phosphoric acid (PA) and triflate ion (TFA) is performed for high temperature PEM fuel cells. Classical MD simulations are employed to compare the structure and dynamics of ABPBI+PA, ABPBI+TFA and ABPBI+PA+TFA blends at varying hydration. The effect of different parameters such as thermostat, coupling time and system size for the accurate determination of shear viscosity is examined using an Extended Simple Point Charge (SPC/E) water model. The relation of electrostatic, cation-phenyl and C-H/phenyl interactions with the structure and dynamics of benzyl-NX3(X=methyl, ethyl) trifluoromethanesulfonate ILs is characterized using MD simulations and Electro-chemical Impedance Spectroscopy (EIS). The characterization of the role of asymmetry of cation and N-H/pi interactions in proton transfer using ab initio MD can be the focus of future activities. Such a study can provide further insights to design novel protic ILs for various technological applications. en_US
dc.description.sponsorship University Grants Commissions, New Delhi; National Council of Science and Technology Communication, Department of Science and Technology, New Delhi en_US
dc.language.iso en en_US
dc.subject Polymer Electrolyte Membranes en_US
dc.subject Ionic Liquids en_US
dc.subject Molecular Dynamics en_US
dc.subject Structure Factor en_US
dc.subject Scattering Intensity en_US
dc.subject Radius of gyration en_US
dc.subject Electro-chemical Impedance Spectroscopy en_US
dc.subject Ionic Conductivity en_US
dc.subject Diffusion coefficient en_US
dc.title Atomistic investigation of polymer electrolyte membrane nanostructure and dynamics of molecular transport in fuel cells en_US
dc.type Thesis en_US


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