A computer simulation study of ionic conductivity in polymer electrolytes

TL;DR

This study uses computer simulations to analyze ionic conductivity in solid polymer electrolytes, considering phase heterogeneity and dynamic reorganization, aligning well with experimental data.

Contribution

It introduces a novel simulation approach accounting for phase reorganization over relevant time scales in polymer electrolytes.

Findings

Conductivity variation with salt concentration matches experimental trends.

Estimated jump distances are consistent with known polymer bond lengths.

Simulation captures the multiphase nature of polymer electrolytes.

Abstract

In this paper we present a computer simulation study of ionic conductivity in solid polymeric electrolytes. The multiphase nature of the material is taken into account. The polymer is represented by a regular lattice whose sites represent either crystalline or amorphous regions with the charge carrier performing a random walk. Different waiting times are assigned to sites corresponding to the different phases. A random walk (RW) is used to calculate the conductivity through the Nernst-Einstein relation. Our walk algorithm takes into account the reorganisation of the different phases over time scales comparable to time scales for the conduction process. This is a characteristic feature of the polymer network. The qualitative nature of the variation of conductivity with salt concentration agrees with the experimental values for PEO-NH$_{4}$I and PEO-NH$_{4}$SCN. The average jump distance estimated from our work is consistent with the reported bond lengths for such polymers.