Date of Award
8-2025
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Physics and Astronomy
Committee Chair/Advisor
Dr. Apparao M. Rao
Committee Member
Dr. Srikanth Pilla
Committee Member
Dr. Mark Leising
Committee Member
Dr. Sriparna Bhattacharya
Committee Member
Dr. Morteza Sabet
Abstract
Lithium-ion batteries (LIBs) power a wide range of modern devices, from smartphones to electric vehicles. This dissertation integrates materials characterization and electrochemical testing to develop novel Si-based electrode materials, investigate separator effects, and improve electrochemical impedance spectroscopy (EIS) modeling. First, I synthesized Si@CC composites using bio-based carbon sources and discovered a novel in situ disorder reduction in the amorphous carbon cloud during cycling, attributed to Si volume fluctuations and mesoporous carbon structure, which enhanced capacity retention. A binder-free electrode (Si@CC@BP) using bucky paper further improved gravimetric and areal capacities while reducing weight and manufacturing complexity.
Next, I investigated how separator polymer strand dynamics induce electrolyte advection, influencing dendrite-free metal plating, transference number measurements, and capacity oscillations. This work challenges the Bruce-Vincent method by showing that transference numbers depend on both electrolyte and separator and calls for a new parameter incorporating electrolyte flow.
Finally, I developed a Finite-Length Diffusion Equivalent Circuit Model (FLD-EECM) for EIS analysis, which captures mid- and high-frequency Warburg impedance effects overlooked by conventional models. This model provided more accurate estimates of key battery parameters, such as diffusion coefficients and charge transfer resistance, differing by over 5% from traditional methods.
Overall, my dissertation identifies novel phenomena and provides practical tools to improve the performance, reliability, and modeling of lithium-ion batteries for future applications.
Recommended Citation
Karki, Peshal, "Advancing Lithium-Ion Batteries Through Exploration of Novel Physico-Chemical Phenomena" (2025). All Dissertations. 4045.
https://open.clemson.edu/all_dissertations/4045
Author ORCID Identifier
0009-0005-0163-8545