Date of Award:


Document Type:


Degree Name:

Doctor of Philosophy (PhD)


Electrical and Computer Engineering

Committee Chair(s)

Regan Zane


Regan Zane


Hongjie Wang


Kandler Smith


Gregory L. Plett


Dragan Maksimović


Abhilash Kamineni


The transportation sector is a significant contributor to global greenhouse gas emissions. Adopting electric vehicles (EVs) has been recognized as a critical strategy to decarbonize this sector. Energy storage systems, primarily consisting of batteries, play a crucial role in realizing equitable electric mobility solutions. However, technical challenges, such as limitations in battery capacity, power, energy, lifetime, and cost, hinder the widespread adoption of electric mobility and energy storage solutions. Optimizing battery systems for energy and power density targets with a single-chemistry solution is complex and costly, requiring new battery development for each target set. This dissertation proposes a novel composite hybrid energy storage system (CHESS) that offers a solution by integrating energy-dense and power-dense energy storage elements in a single unit at a system level. The CHESS architecture provides more flexibility to meet a range of power and energy density targets using existing chemistries without requiring a new battery design for every set of targets and reduces the energy storage weight. It balances energy between the two battery packs to enhance their utilization and performance while providing power to auxiliary loads under dynamic loads. The dissertation proposes a novel power converter topology to mitigate mismatches in the characteristics of battery cells, enabling a prolonged life. As EV adoption proliferates, many retired lithium-ion batteries are expected to be discarded, leading to environmental, public health and safety, economic, and sustainability concerns. Utilizing the remaining capacity in retired lithium-ion batteries for second-life applications has demonstrated economic and environmental benefits. However, achieving homogeneity among the cells before the second life is critical in exploiting these benefits. This dissertation proposes a new active reconditioning approach that could make short-term reconditioning of batteries before their second life feasible. The control strategy can achieve homogeneity in cell capacities while providing ancillary services to the grid. This thesis represents a significant advancement in the field of hybrid battery systems. The proposed innovations in architectural design, operation, and active balancing control, coupled with the pioneering reconditioning solution for retired EV batteries, contribute to state-of-the-art energy storage technologies.



Available for download on Tuesday, August 01, 2028