Correlation of Structure to Performance of Soft Materials for Energy Storage Systems Using Neutron Scattering

This dissertation presents work that expands our understanding of the relation between the structural features of soft materials applicable in energy storage systems such as redox flow batteries (RFB) and organic radical batteries (ORB) to their performance. The studies focus on soft materials- nanoparticle organic hybrid materials (NOHMs) and the radical polymer, poly (2,2,6,6-tetramethylpeperidinyloxy-4-yl methacrylate) (PTMA). The results obtained in these studies provide a holistic understanding of the structural features of NOHMs and PTMA in solution that may provide insight to rationally improve the performance of energy storage systems.

The first two projects investigate the structure and assembly of nanoparticle organic hybrid materials (NOHMs) in aqueous solution with and without supporting electrolytes using small angle neutron scattering. The first project focuses on the structure and assembly of the polymer canopy and NOHMs with increasing concentrations of NOHMs in aqueous solution with and without supporting electrolyte. The research highlights that a large amount of polymer ungrafts from the nanoparticle surface to free polymer that interact with the grafted polymer canopy. The second project explores the impact of tuning the bonding type (ionic vs. covalent) of the polymer canopy grafted to the nanoparticle in the structure and assembly of NOHMs in aqueous solutions with and without supporting electrolyte. In presence of supporting electrolyte, ionic NOHMs structure observe a collapsed polymer conformation on the nanoparticle surface and covalent NOHMs shows a subtle change in conformation of the polymer canopy.

The next part of the research focuses on the assembly of NOHMs near the electrode surface using neutron reflectivity. This research highlights that under applied potential, the ordering of NOHMs dramatically changes, impacting the current density of the NOHMs solution.

The final project investigates the conformation and assembly of PTMA in solutions with variations in radical loading in the PTMA backbone and temperature using small angle neutron scattering. The results highlight that the amount of radical loading is the primary factor governing the final conformation of PTMA. Correlating the conformation of PTMA in solutions to the electrochemical performance indicates that PTMA with collapsed chain conformation improves the charge transfer process.