(622g) Tailoring Surface Functionalization of Silica Nanoparticles in Nafion Nanocomposites for Improved Ion Selectively in Vanadium Redox Flow Batteries | AIChE

(622g) Tailoring Surface Functionalization of Silica Nanoparticles in Nafion Nanocomposites for Improved Ion Selectively in Vanadium Redox Flow Batteries

Authors 

Jansto, A. - Presenter, Clemson University
Davis, E. M., Clemson University
Vanadium redox flow batteries (VRFBs) have emerged as a promising solution for grid-scale energy storage for intermittent energy generation such as wind and solar. However, the polymer electrolyte membrane (PEM), typically a perfluorinated ionomer (e.g., Nafion), utilized in VRFBs suffers from high vanadium crossover, which decreases the lifetime and efficiency of the battery. In response, the introduction of nanoparticles in Nafion has proven to be a successful modification method to reduce the vanadium crossover, though there are conflicting theories on how they act to reduce crossover as recent studies have shown that the nanoparticles reside in both the hydrophobic (Teflon-like) and hydrophilic (ionic) domains. In this study, silica (SiO2) nanoparticle loading, size, and surface chemistry were systematically tailored to elucidate its influence on nanoparticle dispersion in the membrane and examine the role of nanoparticle dispersion in mitigating vanadium crossover. Specifically, several types of interactions between silica nanoparticle surface and Nafion structure were investigated, including electrostatic and covalent interactions within the ionic channels of Nafion, and electrostatic interactions with the hydrophobic Teflon backbone. The effect of these interactions, as it applies to nanoparticle dispersion, was obtained by electron imaging, and vanadium ion permeability through the membrane over time was measured by ultraviolet-visible (UV-Vis) spectroscopy. In addition, the bridging support between silica nanoparticle surface and end group was also investigated, ranging from a relatively flexible, short saturated chain to a significantly less flexible chain containing aromatic groups. Results from this study indicate that the surface functionalization of the silica nanoparticles plays an important role in controlling the permeation of vanadium ions across these nanocomposite membranes.