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Under Pressure: Mechanochemical Effects on Structure and Ion Conduction in the Sodium-Ion Solid Electrolyte Na3PS4

preprint
revised on 22.06.2020 and posted on 24.06.2020 by Theodosios Famprikis, O. Ulas Kudu, James Dawson, Pieremanuele Canepa, François Fauth, Emmanuelle Suard, Mohamed Zbiri, Damien Dambournet, Olaf Borkiewicz, Houssny Bouyanfif, Steffen Emge, Clare P. Grey, Sorina Cretu, Jean-Nöel Chotard, Wolfgang Zeier, Saiful Islam, Christian Masquelier

Fast-ion conductors are critical to the development of solid-state batteries. The effects of mechanochemical synthesis that lead to increased ionic conductivity in an archetypical sodium-ion conductor Na3PS4 are not fully understood. We present here a comprehensive analysis based on diffraction (Bragg, pair distribution function), spectroscopy (impedance, Raman, NMR, INS) and ab-initio simulations aimed at elucidating the synthesis-property relationships in Na3PS4. We consolidate previously reported interpretations about the local structure of ball-milled samples, underlining the sodium disorder and showing that a local tetragonal framework more accurately describes the structure than the originally proposed cubic one. Through variable-pressure impedance spectroscopy measurements, we report for the first time the activation volume for Na+ migration in Na3PS4, which is ~30% higher for the ball-milled samples. Moreover, we show that the effect of ball-milling on increasing the ionic conductivity of Na3PS4 to ~10-4 S/cm can be reproduced by applying external pressure on a sample from conventional high temperature ceramic synthesis. We conclude that the key effects of mechanochemical synthesis on the properties of solid electrolytes can be analyzed and understood in terms of pressure, strain and activation volume.

History

Email Address of Submitting Author

famprikis@gmail.com

Institution

Laboratoire de Réactivité et Chimie des Solides CNRS, Université de Picardie Jules Verne

Country

France

ORCID For Submitting Author

0000-0002-7946-1445

Declaration of Conflict of Interest

no conflict of interest

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