Date of Award
December 2025
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Energy Engineering
First Advisor
Xiaodong Hou
Abstract
Silicon monoxide (SiO)-graphite composite anodes have emerged as promising candidates for next-generation lithium-ion batteries (LIBs) due to their high energy density and favorable electrochemical behavior. However, the heterogeneous nature of composite electrodes characterized by multiple particle sizes, nonlinear reaction kinetics, and intricate transport pathways poses challenges in predicting and optimizing their lithiation performance. This dissertation investigates these challenges through three integrated research studies employing computational modeling, electrode engineering, and fast charging of LIBs at subzero temperatures.
In the first part of this work, a SiO-graphite composite electrode is systematically analyzed to understand the effects of SiO proportion, C-rate, and particle size on electrochemical performance. A physics model developed in COMSOL Multiphysics 6.1 reveals that electrodes with higher SiO content exhibit improved rate capability due to enhanced charge storage capacity. While a relatively uniform state of charge (SOC) distribution is observed at low C-rates, significant SOC heterogeneity develops between graphite and SiO particles at high C-rates. An optimized particle size for both materials is proposed to narrow this SOC gap, enabling a half-cell with 30.27 wt.% SiO to deliver 432 mAh/g at 2C, with an approximately 9% deviation between simulation and experiment.
The second part of this work explores engineered electrode architectures to mitigate transport limitations during high-rate operation. At a coating thickness of 55 μm, this design improves capacity by approximately 2% (440 mAh/g) compared to randomly distributed particles, and further optimization increases the capacity to 475 mAh/g.
The final part of the dissertation addresses fast charging under subzero environmental conditions, where electrolyte conductivity and ion mobility are severely reduced. A lithium cobalt oxide (LCO)/graphite full cell is modeled using the Python Battery Mathematical Modeling (PyBaMM) framework to develop an optimized multi-stage charging protocol for operation at 258.15 K.The proposed strategy integrates (1) pulse charge-discharge preheating, (2) constant-current charging, and (3) constant-voltage charging. Pulse currents are used to increase the cell temperature while maintaining a capacity protection ratio to avoid over-discharge. The optimized protocol successfully raises the cell temperature from 258.15 K to 278.15 K within approximately 6.7 minutes, enabling safe and efficient subsequent fast charging.
Recommended Citation
Ahmed, Rahate, "Improvement Of Lithium-Ion Battery’s Fast Charging Capability Through Anode Design And Charging Algorithm: A Modeling And Experimental Investigation" (2025). Theses and Dissertations. 8205.
https://commons.und.edu/theses/8205