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Title: Conduction Mechanisms and Structure of Ionomeric Single-Ion Conductors

Our team has designed using DFT (Gaussian) and synthesized low glass transition temperature single-ion conductors that are either polyanions that conduct small cations Li, Na, Cs or polycations that conduct small anions F, OH, Br. We utilize a wide range of complimentary experimental materials charactization tools to understand ion transport; differential scanning calorimetry, dielectric relaxation spectroscopy, infrared spectroscopy, nuclear magnetic resonance spectroscopy, linear viscoelasticity, X-ray scattering and molecular dynamics simulations. The glass transition temperature Tg needs to be as low as possible to facilitate ion transport, so the nonionic parts of the polymer need to be polar, flexible and have strong solvation interactions with the ions. The lowest Tg we have managed for polyanions conducting Li is -60 C. In contrast, polysiloxanes with PEO side chains and tetrabutylphosphonium cationic side groups have Tg ~ -75C that barely increases with ion content, as anticipated by DFT. A survey of all polyanions in the literature suggests that Tg < -80C is needed to achieve the 10-4 S/cm conductivity needed for battery separators.
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Publication Date:
OSTI Identifier:
Report Number(s):
DOE Contract Number:
Resource Type:
Technical Report
Research Org:
The Pennsylvania State University
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Contributing Orgs:
The Pennsylvania State University
Country of Publication:
United States
36 MATERIALS SCIENCE conduction mechanisms, ionomeric single-ion conductors