Scientists crack the code on a promising material for next-gen batteries
Researchers have mapped out how PEDOT/Nafion—a hybrid polymer that conducts both electricity and ions—organizes itself at the molecular level. The findings could accelerate development of better batteries, fuel cells, and energy storage devices by showing manufacturers exactly how to tune the material's performance.
Originaltitel: Morphology and Structure of PEDOT:Nafion: Insights from Experiment and Molecular Dynamics Simulations
<p>Poly(3,4-ethylenedioxythiophene) (PEDOT)/Nafion is a promising mixed ionic-electronic conducting polymer. However, in contrast to the well-studied PEDOT:poly(styrenesulfonate) (PSS) system, the nanoscale morphology and the relationship between crystallinity and composition in PEDOT/Nafion remain insufficiently explored and therefore poorly understood. In this work, we investigate the morphology and structural organization of PEDOT/Nafion by combining X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and coarse-grained molecular dynamics (MD) simulations. This combined approach enables us to directly link surface composition, bulk crystallinity, and molecular-scale packing in PEDOT/Nafion-insights that are not accessible from PEDOT:PSS or Nafion-only studies. XPS revealed two distinct sulfur environments associated with PEDOT and Nafion, with a sulfonic-acid-to-thiophene-group ratio R-S/T of approximate to 2.3. XRD analysis showed PEDOT crystallites with an average pi-pi stacking size of about 2.1 nm. MD simulations provided molecular-level insight into the effect of composition, demonstrating that higher Nafion content disrupts PEDOT stacking, yielding smaller crystallites (similar to 1.1 nm), while reduced Nafion content promotes better ordering (similar to 1.4-1.8 nm). These findings establish a clear correlation between composition and crystallinity, supporting a model where the surface is Nafion-rich and the bulk has a lower R-S/T ratio. The combined experimental-computational approach offers a comprehensive understanding of PEDOT morphology and valuable guidance for the design of mixed ion-electron conducting polymers.</p>