Author ORCID Identifier
https://orcid.org/0000-0002-9173-0169
Defense Date
2026
Document Type
Dissertation
Degree Name
Doctor of Philosophy
Department
Chemistry
First Advisor
Hani M. El-Kaderi
Abstract
The increasing global demand for sustainable, high-energy-density energy storage systems has stimulated extensive research into alternatives to conventional lithium-ion batteries. Among the most promising candidates, lithium-sulfur batteries (LSBs) have attracted considerable attention because of their high theoretical specific energy, low cost, environmental compatibility, and the natural abundance of sulfur. However, the practical implementation of LSBs remains limited by several persistent challenges, including the intrinsically low electronic conductivity of sulfur and lithium sulfide, sluggish sulfur redox kinetics, severe polysulfide dissolution and shuttle behavior, large volume changes during cycling, and poor electrochemical performance under high sulfur loading conditions. These issues collectively lead to low sulfur utilization, rapid capacity fading, and insufficient long-term stability. The objective of research projects described in this dissertation is to develop advanced sulfur cathode materials and electrode architectures that address these limitations through the combined strategies of electrocatalyst design, interfacial engineering, and additive manufacturing. Three complementary research directions were investigated.
First, a selective reduction approach was employed to convert the multivariate metal-organic framework MTV-MOF-74 (Co, Ni, Fe) into a porous carbon host decorated with CoNi alloy and Fe3O4 nanoparticles. The resulting heterostructure provided strong polysulfide adsorption and accelerated redox conversion. As a result, the sulfur cathode delivered a high reversible capacity of 1439.8 mAh g-1 at 0.05 C, sustained stable cycling for 1000 cycles at 1 C with only 0.018% capacity decay per cycle under lean-electrolyte conditions, demonstrating excellent practicality.
Second, direct ink writing (DIW) was utilized to fabricate freestanding 3D printed sulfur cathodes incorporating Co/Ni dual-site atomic catalysts supported on nitrogen-doped carbon. The architected hierarchical porous structure significantly enhanced electrolyte accessibility and ion transport in thick electrodes. The optimized printed cathode delivered a reversible capacity of 1041.4 mAh g-1 at 1 C with 85.5% retention after 1000 cycles, while maintaining a high sulfur loading of 8.1 mg cm-2 with an areal capacity of 12.5 mAh cm-2, highlighting the effectiveness of combining catalyst engineering with 3D electrode design.
Third, MXene/carbon nano-onion (MXene/CNO) heterostructure was developed as a multifunctional sulfur host. Strong interfacial coupling between polar MXene and conductive carbon nano-onions generated Ti-O-C active interfaces that enhanced polysulfide anchoring and reaction kinetics. The resulting cathode exhibited a high reversible capacity of 1171.1 mAh g-1 at 0.1 C and stable cycling for 1500 cycles at 1 C with only 0.027% capacity decay per cycle, demonstrating exceptional long-term durability.
Overall, the results of this dissertation demonstrate that the major limitations of LSBs can be effectively mitigated through the synergistic optimization of catalytic activity, interfacial chemistry, and electrode architecture. The materials and design principles established herein provide important insights into structure-property-performance relationships in sulfur cathodes and offer scalable pathways toward practical high-energy LSBs. Furthermore, these strategies are broadly applicable to other conversion-type energy storage systems, including sodium-sulfur batteries and emerging solid-state printed energy devices.
Rights
© 2026 Mahmoud M. Kaid
Is Part Of
VCU University Archives
Is Part Of
VCU Theses and Dissertations
Date of Submission
6-10-2026