TY - JOUR
T1 - Control of Ionic Mobility via Charge Size Asymmetry in Random Ionomers
AU - Ma, Boran
AU - Nguyen, Trung Dac
AU - Olvera De La Cruz, Monica
N1 - Funding Information:
This work was supported by the U.S. Department of Commerce, National Institute of Standards and Technology as part of the Center for Hierarchical Materials Design (CHiMaD) under award 70NANB14H012. The authors thank the computational support of the Sherman Fairchild Foundation. B. M. thanks Dr. Rebecca Holmes and Ali Ehlen for reading the manuscript.
Publisher Copyright:
Copyright © 2019 American Chemical Society.
PY - 2020/1/8
Y1 - 2020/1/8
N2 - Solid polymer electrolytes are considered a promising alternative to traditional liquid electrolytes in energy storage applications because of their good mechanical properties, and excellent thermal and chemical stability. A gap, however, still exists in understanding ion transport mechanisms and improving ion transport in solid polymer electrolytes. Therefore, it is crucial to bridge composition-structure and structure-property relationships. Here, we demonstrate that size asymmetry, λ, represented by the ratio of counterion to charged monomer size, plays a key role both in the nanostructure and in the ionic dynamics. More specifically, when the nanostructure is modified by an external electric field such that the mobility cannot be described by linear response theory, two situations arise. The ionic mobility increases as λ decreases (small counterions) in the weak electrostatics (high dielectric constant) regime, whereas in systems with strong electrostatic interactions, ionomers with higher size symmetry (λ ≈ 1) display higher ionic mobility. Moreover, ion transport is found to be dominated by the hopping of the ions and not by moving ionic clusters (also known as "vehicular" charge transport). These results serve as a guide for designing ion-containing polymers for ion transport related applications.
AB - Solid polymer electrolytes are considered a promising alternative to traditional liquid electrolytes in energy storage applications because of their good mechanical properties, and excellent thermal and chemical stability. A gap, however, still exists in understanding ion transport mechanisms and improving ion transport in solid polymer electrolytes. Therefore, it is crucial to bridge composition-structure and structure-property relationships. Here, we demonstrate that size asymmetry, λ, represented by the ratio of counterion to charged monomer size, plays a key role both in the nanostructure and in the ionic dynamics. More specifically, when the nanostructure is modified by an external electric field such that the mobility cannot be described by linear response theory, two situations arise. The ionic mobility increases as λ decreases (small counterions) in the weak electrostatics (high dielectric constant) regime, whereas in systems with strong electrostatic interactions, ionomers with higher size symmetry (λ ≈ 1) display higher ionic mobility. Moreover, ion transport is found to be dominated by the hopping of the ions and not by moving ionic clusters (also known as "vehicular" charge transport). These results serve as a guide for designing ion-containing polymers for ion transport related applications.
KW - Size asymmetry
KW - ionic dynamics
KW - molecular dynamics simulation
KW - random ionomers
KW - solid polymer electrolytes
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U2 - 10.1021/acs.nanolett.9b02743
DO - 10.1021/acs.nanolett.9b02743
M3 - Article
C2 - 31769988
AN - SCOPUS:85076240183
VL - 20
SP - 43
EP - 49
JO - Nano Letters
JF - Nano Letters
SN - 1530-6984
IS - 1
ER -