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First Principles Investigations of Solid-Solid Interfaces in Lithium Battery Materials

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title
First Principles Investigations of Solid-Solid Interfaces in Lithium Battery Materials
author
Lepley, Nicholas D.
abstract
This work explains some of the current issues driving the development of Li batteries and some of the current research opportunities. In particular it focuses on using ab initio theoretical methods to model electrode/electrolyte interfaces for inorganic solid electrolyte materials, especially those related to Li$_3$PS$_4$. I develop a general scheme based on the interface energy for analyzing interfaces between crystalline solids, quantitatively including the effects of varying configurations and lattice strain. This scheme is successfully applied to the modeling of likely interface geometries of several solid state battery materials including Li metal, Li$_3$PO$_4$, Li$_3$PS$_4$, Li$_2$O, and Li$_2$S. This formalism, together with partial density of states analysis, allows me to characterize the extent, stability, and transport properties of these interfaces. My investigation finds that all of the interfaces in this study are stable with the exception of Li$_3$PS$_4$/Li. For this chemically unstable interface, the partial density of states helps to identify mechanisms associated with the interface reactions. The energetic measure of interfaces and analysis of the band alignment between interface materials indicate multiple factors which may be predictors of interface stability, an important property of electrolyte systems.
subject
Density Functional Theory
Interfaces
Lithium batteries
Solid electrolytes
contributor
Holzwarth, Natalie (committee chair)
Salsbury, Freddie (committee member)
Kerr, William (committee member)
Thonhauser, Timo (committee member)
Salam, Akbar (committee member)
date
2016-01-11T09:35:29Z (accessioned)
2016-01-11T09:35:29Z (available)
2015 (issued)
degree
Physics (discipline)
identifier
http://hdl.handle.net/10339/57445 (uri)
language
en (iso)
publisher
Wake Forest University
type
Dissertation

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