Stiff solid ion conductors based on a double helix polyelectrolyte

Louis A. Madsen
Department of Chemistry and Macromolecules Innovation Institute, Virginia Tech
[email protected]

Collective intermolecular interactions can give rise to surprising material properties. I will describe a new class of materials that we term molecular ionic composites (MICs). MICs simultaneously possess high mechanical stiffness (E’ up to 3 GPa) and yet liquid-like motions of ions inside (conductivity up to 8 mS/cm).1 MICs show promise for enabling, e.g., high density and safe Li and Na batteries, as well as a host of other electrochemical and molecular separations devices.
MICs appear to consist of a collective electrostatic network that enables their transport and mechanical properties, and these materials are stable conductors from -50 to +300°C.1 The figure below (MD simulation, looking down polymer rod axes) illustrates their extensive ionic correlations.2 The sulfonated Kevlar®-like polymer forms a double helix that provides a rigidity persistence length of ~ 1 micrometer along the rod axis (20X that of DNA), thus representing a new 1D material building block.3 I will discuss the phenomena that give rise to MIC properties, and will provide insights into transport of ions in such nanoconfined systems.



1. Y. Wang, Y. Chen, J. Gao, H. G. Yoon, L. Jin, M. Forsyth, T. J. Dingemans, and L. A. Madsen. Advanced Materials (2016). DOI: 10.1002/adma.201505183.
2. Z. Yu, Y. He, Y. Wang, L. A. Madsen, and R. Qiao. Langmuir (2017). DOI: 10.1021/acs.langmuir.6b03798.
3. Y. Wang, Y. He, Z. Yu, J. Gao, S. ten Brinck, C. Slebodnick, G. B. Fahs, C. J. Zanelotti, M. Hegde, R. B. Moore, B. Ensing, T. J. Dingemans, R. Qiao, and L. A. Madsen. Nature Communications (2019). DOI: 10.1038/s41467-019-08756-3.