5 min read

Electric Dipoles and Ionic Conductivity in a Na+ Glass Electrolyte

Latest updated: May 29, 2020
Authors: M. Helena Braga, Jorge A. Ferreira, Andrew J. Murchison and John B. Goodenough
Ref: Journal of The Electrochemical Society 2017, volume 164, issue 2, A207-A213

Abstract

Glass, unlike a crystalline solid, contains atoms and molecules that do not occupy fixed positions. A glass that contains molecules that attract one another can age with time. We report such a glass that contains A2O and (OA) electric dipoles (A = Li or Na). At a temperature T < 1.2Tg ≈ 110°C (Tg is the glass transition temperature) the electric dipoles coalesce with time into clusters within which, unlike in ice, some dipoles condense into ferroelectric, negatively charged molecules locally charge-compensated by weakly attracted A+ ions. In an applied electric field, the dipoles are oriented and, over time depending on the T < 110°C, are aligned parallel to the field axis to yield a solid A+ electrolyte with an ionic conductivity σi > 10−2 S cm−1 and a huge dielectric constant that makes it suitable for many applications, including safe rechargeable batteries of high energy density and long cycle life.
batteries dielectrics electrolytes glasses

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