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Published January 28, 2025 | Version v1
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Water-mediated ion transport in an anion exchange membrane

Creators

  • 1. University of Chicago
  • 2. Georgia Institute of Technology
  • 3. Argonne National Laboratory

Description

Water is a critical component in polyelectrolyte anion exchange membranes (AEMs). It plays a central role in ion transport in electrochemical systems. Gaining a better understanding of molecular transport and conductivity in AEMs has been challenged by the lack of a general methodology capable of capturing and connecting water dynamics, water structure, and ionic transport over time and length scales ranging from those associated with individual bond vibrations and molecular reorientations to those pertaining to macroscopic AEM performance. In this work, we use two-dimensional infrared spectroscopy and semiclassical simulations to examine how water molecules are arranged into successive solvation shells, and we explain how that structure influences the dynamics of bromide ion transport processes in polynorbornene-based materials. We find that the transition to the faster transport mechanism occurs when the reorientation of water molecules in the second solvation shell is fast, allowing a robust hydrogen bond network to form. Our findings provide molecular-level insights into AEMs with inherent transport of halide ions, and help pave the way towards a comprehensive understanding of hydroxide ion transport in AEMs.

Data availability

All data are available within the main text and the supplementary materials.

The MD simulations were conducted using the commercially available package Gromacs. Details required to reproduce the computations and the code supporting the key findings of this study have been provided in the "Methods" section and Supplementary Information. Additional codes used in this study are available from the corresponding authors upon request.

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Additional details

Identifiers

DOI
10.1038/s41467-024-55621-z
Other
oai:uchicago.tind.io:14474

Funding

Division of Materials Science and Engineering, Office of Basic Energy Sciences, Department of Energy

UChicago Information

Division(s)
Physical Sciences Division, Pritzker School of Molecular Engineering
Department(s)
Chemistry
Center(s) or Institute(s)
James Franck Institute