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Updated: Jul 17, 2025

Assembly and Characterization of Polyelectrolyte Complex Micelles
Published on: March 2, 2020
Ion Solvation Cage Structure in Polymer Electrolytes Determined by Combining X-ray Scattering and Simulations
Chao Fang1,2, Saheli Chakraborty1,3, Yunhao Li1
1Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720, United States of America.
Abstract:
Solvation structure plays a crucial role in determining ion transport in electrolytes. We combine wide-angle X-ray scattering (WAXS) and molecular dynamics (MD) simulation to identify the solvation cage structure in two polymer electrolytes, poly(pentyl malonate) (PPM) and poly(ethylene oxide) (PEO) mixed with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt. As the salt concentration increases, the amorphous halo in the pure polymers is augmented by an additional peak at low scattering angles. The location of this peak and its height are, however, different in the two electrolytes. By decoupling the total intensity into species contributions and mapping scattering peaks to position-space molecular correlations, we elucidate distinct origins of the additional peak. In PPM, it arises from long-range charge-ordering between solvation cages and anions, while in PEO it is dominated by correlations between anions surrounding the same cage. TFSI- ions are present in the PPM solvation cage, but expelled from the PEO solvation cage.
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