Document Type
Dissertation - Open Access
Award Date
2023
Degree Name
Doctor of Philosophy (PhD)
Department / School
Electrical Engineering and Computer Science
First Advisor
Xiaojun Xian
Abstract
Constructing an artificial solid electrolyte interphase (SEI) on lithium metal electrode is a promising approach to address the rampant growth of dangerous lithium morphologies (dendritic and dead Li0) and low Coulombic efficiency that plague development of lithium metal batteries. But it is not known how the Li+ transfer behavior in the SEI is coupled with mechanical properties. We demonstrate here a facile and scalable solution-processed approach to form a Li3N-rich SEI with a phase-pure crystalline structure that minimizes the diffusion energy barrier of Li+ across the SEI. Compared with a polycrystalline Li3N SEI obtained from conventional approaches, our phase-pure/single crystalline Li3N-rich SEI constitutes an interphase of high mechanical strength and a low Li+ diffusion barrier. We elucidate the correlation among Li+ transference number, diffusion behavior, concentration gradient, and the stability of the lithium metal electrode by integrating phase field simulations with experiments. We demonstrate extreme reversibility and ultra-stable charge/discharge cycling behaviors for both symmetric cells and full lithium-metal batteries constructed using this Li3N-rich SEI. These studies provide new insight into the designing and engineering of an ideal artificial SEI for stable and high-performance lithium metal batteries. The fast depletion of fossil fuel has brought severe energy crises. hindering social progress and threatens human development. The increasing global energy demand requires the development of renewable energy storage technologies. Supercapacitors, or electrical double layer capacitors (EDLCs), seem to be the most likely candidates for the next generation of energy storage devices. Supercapacitors possesses the advantage of the conventional capacitors and ionic batteries, and their properties include high power density, fast charge/discharge rate, long cycle life and environmental friendliness. Although EDLC holds great promises for fast-charging energy storage devices but suffers from a limited specific capacitance. The design and development of high performance EDLC-type carbon materials with the effective synergistic effect of high conductivity, tailored porous structure, and high surface area still remain challenging. Here, we report a novel hierarchical porous carbon with a combination of highly conductive electronic pathways and rich ionic storage units in three-dimensional network morphology, leading to high specific capacitance of EDLC. Specifically, by facile hydrothermal synthesis and carbonization, the carbon electrode derived from metal-organic framework and polymer fibers, exhibits extremely high specific capacitance of ~ 385 F g-1 at 0.1 A g-1 and can still maintain capacitance of 303 F g-1 at 10 A g-1. The high electrochemical performance can be attributed to the rich network of micro and mesoporous structures for electrolyte transport and ion adsorption as well as highly conductive electronic pathways inside the electrodes. The assembled EDLC thus delivers a high energy density of 10.53 Wh kg-1 and a power density of 5.454 kW kg-1 at the current density of 10 A g-1 in aqueous electrolyte. Hence, the present study is expected to open a promising route to developing porous materials for high-performance energy devices.
Library of Congress Subject Headings
Lithium ion batteries.
Storage batteries.
Supercapacitors.
Energy storage.
Publisher
South Dakota State University
Recommended Citation
Pokharel, Jyotshna, "Electrochemical Innovations: Advancements in Lithium Metal Batteries & Supercapacitor For Energy Storage" (2023). Electronic Theses and Dissertations. 879.
https://openprairie.sdstate.edu/etd2/879
Rights Statement
