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Title: Communication: Nanoscale ion fluctuations in Nafion polymer electrolyte

Ion conduction mechanisms and the nanostructure of ion conduction networks remain poorly understood in polymer electrolytes which are used as proton-exchange-membranes (PEM) in fuel cell applications. Here we study nanoscale surface-potential fluctuations produced by Brownian ion dynamics in thin films of low-hydration Nafion™, the prototype PEM. Images and power spectra of the fluctuations are used to derive the local conductivity-relaxation spectrum, in order to compare with bulk behavior and hopping-conductivity models. Conductivity relaxation-times ranged from hours to milliseconds, depending on hydration and temperature, demonstrating that the observed fluctuations are produced by water-facilitated hydrogen-ion hopping within the ion-channel network. Due to the small number of ions probed, non-Gaussian statistics of the fluctuations can be used to constrain ion conduction parameters and mechanisms.
Authors:
; ; ;  [1] ;  [2]
  1. Department of Physics, Northeastern University, Boston, Massachusetts 02115 (United States)
  2. National Institute of Standards and Technology, Center for Neutron Research, Gaithersburg, Maryland 20899 (United States)
Publication Date:
OSTI Identifier:
22419790
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 141; Journal Issue: 7; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 77 NANOSCIENCE AND NANOTECHNOLOGY; ELECTROLYTES; FLUCTUATIONS; FUEL CELLS; HYDROGEN IONS; MEMBRANES; NANOSTRUCTURES; POLYMERS; PROTONS; SPECTRA; THIN FILMS