Ion-mediated charge transport in ionomeric electrolytes.

Area of Science:

• Polymer science
• Materials science
• Electrochemistry

Background:

• Ionomers are model systems for studying ion transport in polymers.
• Conductivity depends on net charge transport, influenced by ion diffusion mechanisms.
• Paired ion diffusion contributes negligibly to conductivity.

Purpose of the Study:

• To investigate the ion transport mechanism in sodium-neutralized poly(PEO-co-sulfoisophthalate) using molecular dynamics.
• To understand how ion aggregation affects conductivity in ionomers.
• To explore the role of cation relaying and correlated ion transport.

Main Methods:

• Coarse-grained molecular dynamics simulations.
• Analysis of ion coordination, aggregation, and transport pathways.
• Investigation of diffusion coefficients and conductivity contributions.

Main Results:

• Ion transport is mediated by coordination with ion pairs and clusters due to high ion density.
• Evidence of efficient cation relaying mechanism observed.
• Larger ion aggregates act as conductive pathways for cations.
• Highly ordered ion aggregate networks enhance conductivity through correlated transport.

Conclusions:

• Ion transport in this ionomer is dominated by cluster-mediated mechanisms, not solely individual ion diffusion.
• Cation relaying and correlated motion within ordered ion aggregate networks are key to high conductivity.
• Molecular dynamics simulations provide insights into optimizing ionomer conductivity.