Date of Award

Summer 8-30-2025

Document Type

Campus Access Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry/Physical/Analytical Chemistry

First Advisor

Niya Sa

Second Advisor

Jason Green

Third Advisor

Qingjiang Li

Abstract

This dissertation employs continuum modeling to investigate ion dynamics and electrochemical kinetics across diverse systems, addressing critical challenges in energy storage and electrokinetic applications. The study integrates experimental and computational approaches to explore multivalent ion additives in silicon anodes for lithium-ion batteries, revealing that Mg2+ co-alloying stabilizes silicon under Li-rich conditions. A modified Pseudo-Two-Dimensional (P2D) model illustrates the interplay between Li and Mg kinetics. Further, ion transport in nanopores under alternating current fields is visually shown by ion dynamics, highlighting frequency-dependent transitions between electromigration-dominated non-equilibrium states and diffusion-controlled quasi-equilibrium regimes. Conical nanopores exhibit overlapping surface-charge effects at 20 nm scales, while larger pores favor bulk-like ion dynamics. Another model investigates multi-redox reaction kinetics by Finite element simulations of rotating ring-disk electrode (RRDE) and Cyclic voltammetry (CV) systems, showing that convection speed, exchange current density, etc., parameters critically influence current response. Finally, the modified P2D model optimizes high-voltage cathode designs, correlating porosity gradients and solid-state diffusion coefficients with cathode electrolyte interphase formation reactions. By bridging nanoscale phenomena, such as electric double layer overlaps, to device-scale performance, this work advances strategies for high-energy-density batteries, electrokinetic sensors, and ion-selective membranes. The findings emphasize the role of continuum models in complex ion dynamics and accelerating material design for sustainable energy technologies.

Comments

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