Ionic conductivity mechanisms in PEO–NaPF6 electrolytes

Abstract

Understanding ion transport mechanisms in sodium ion-based polymer electrolytes is critical, considering the emergence of sodium ion electrolyte technologies as sustainable alternatives to lithium-based systems. In this paper, we employ all-atom molecular dynamics simulations to investigate the salt concentration (c) effects on ionic conductivity (σ) mechanisms in sodium hexafluorophosphate (NaPF6) in polyethylene oxide (PEO) electrolytes. Sodium ions exhibit ion solvation shell characteristics comparable to those of lithium-based polymer electrolytes, with similar anion coordination but more populated oxygen coordination in the polymer matrix. We find that the diffusion coefficient of Na+ and PF6 follows the Stokes–Einstein behavior with viscosity (η) and ion-pair relaxation timescales (τc): D+τc−0.87, Dτc−0.93, D+η−1.08, and Dη−1.09, emphasizing the role of ion–polymer coordination and relaxation behavior in governing ion transport. Further analysis reveals an intriguing nonmonotonic trend in the Nernst–Einstein and true ionic conductivity as a function of c, peaking near c = 1 M. We model this behavior as σcα exp(−c/c0), where the nonlinear term (α = 1.6) reflects efficient ion transport due to the absence of ion–ion correlations at low c, and the exponential decay quantifies viscosity-driven losses in ionic conductivity at high c. Our work establishes molecular guidelines to optimize conductivity in sodium-conducting polymer electrolytes, advancing next-generation sodium ion electrolyte technologies.

Graphical abstract: Ionic conductivity mechanisms in PEO–NaPF6 electrolytes

Supplementary files

Article information

Article type
Paper
Submitted
22 Apr 2025
Accepted
31 Aug 2025
First published
09 Sep 2025

Nanoscale, 2025, Advance Article

Ionic conductivity mechanisms in PEO–NaPF6 electrolytes

H. Teherpuria, S. Mohapatra, A. K. Meel, S. S. Paul Chowdhury, S. Kanchi, P. K. Jaiswal and S. Mogurampelly, Nanoscale, 2025, Advance Article , DOI: 10.1039/D5NR01630D

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements