(526f) Molecular Dynamics Characterization of Onsager Transport Coefficients and Transference Number in Polyelectrolyte Solutions
AIChE Annual Meeting
2020
2020 Virtual AIChE Annual Meeting
Materials Engineering and Sciences Division
Charged and Ion-Containing Polymers: Transport and Dynamics
Wednesday, November 18, 2020 - 8:45am to 9:00am
In this work, we aim to understand the emergence of polyelectrolytesâ unique transport properties as we transition from monomeric to oligo- and polymeric anions using coarse-grained molecular dynamics simulations. We perform rigorous calculation of the Onsager transport coefficients, from which we can understand the ion correlations dictating transference number, conductivity, and electrophoretic mobility. We find that cation transference number decreases monotonically with increasing chain length, i.e. in all polyelectrolyte solutions studied, the transference number is lower than that of the monomeric electrolyte. Furthermore, at low concentrations and high chain lengths we observe negative transference number (t+ < 0) due to the presence of long-lived, negatively charged aggregates. These results suggest that while polyelectrolyte solutions may not be promising for use as high transference number electrolytes, they nevertheless offer a unique means of systematically tuning t+ over a very wide range, thereby enabling fundamental studies on the influence of electrolyte transport on battery performance.
- Fong, K. D. et al. Ion Transport and the True Transference Number in Nonaqueous Polyelectrolyte Solutions for Lithium Ion Batteries. ACS Cent. Sci. (2019). doi:10.1021/acscentsci.9b00406