In-situ Characterization of Composition Induced Stresses in Thin Film Oxides: Application to Solid Oxide Fuel Cell and Li-ion Battery Electrodes

Sheth, Jay

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Year:: 2017
Contributor:: Sheth, Jay (creator); Sheldon, Brian (Advisor); Guduru, Pradeep (Reader); Brown University. Engineering: Materials Science Engineering (sponsor)
Genre:: theses
Subject:: Li-ion Batteries; Solid Oxide Fuel Cells; SOFC; batteries; Spinel group; Vanadium pentoxide; doped ceria
Extent:: , None p.
DOI: https://doi.org/10.7301/Z0BG2MGG

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Abstract:: Energy storage and conversion systems rely heavily on the exchange of ions, be it Li-ion batteries (LIBs), which rely on Li+ ions or solid oxide fuel cells (SOFCs) that rely on O2- ions. Exchange of these ions often results in large volumetric changes of the host material, and in constrained geometries, such strains lead to stress build up in the material commonly referred to as compositional stresses. Additionally, heat treatments employed during the growth and fabrication of these systems could also contribute to the stress build up in the material. Given the brittle nature of the oxide ceramic electrodes commonly used in SOFCs and LIBs, such stress build up can lead to mechanical instabilities like fracture or micro-cracks which results in the performance degradation of the device over time, and in extreme cases it could ultimately cause failure of the device. In this dissertation, we will discuss in-situ evolution of the compositional stresses, obtained by wafer curvature measurements, of three material systems; namely 10% Praseodymium doped ceria (PCO, a typical cathode used in intermediate temperature SOFC), spinel Li1+xMn2O4 (LMO) and V2O5 (both LMO and V2O5 are typical cathodes used in LIB), in thin film configuration. The first half of the dissertation discusses in-situ wafer curvature along with high temperature x-ray diffraction (HTXRD) measurements that were employed to measure stresses and strains, respectively on the PCO films during oxidation-reduction cycling and over the pO2 range of 10-1-10-5 atm. at 750oC. This preliminary study is then followed by a discussion on the dependence of these stress and strain on the average grain size of the PCO films. The latter half of the dissertation discusses the in-situ stress evolution in thin films of LMO during electrochemical cycling in a specially designed beaker cell in the 3.5–4.3 V (vs. Li/Li+) voltage range. This is followed by a study that employs thin V2O5 films as model cathode material for LIB, to systematically investigate relationships between stress (intrinsic and extrinsic), phase transformations, and degradation of the cathode.
Notes:: Thesis (Ph. D.)--Brown University, 2017

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Sheth, Jay, "In-situ Characterization of Composition Induced Stresses in Thin Film Oxides: Application to Solid Oxide Fuel Cell and Li-ion Battery Electrodes" (2017). Materials Science Engineering Theses and Dissertations. Brown Digital Repository. Brown University Library. https://doi.org/10.7301/Z0BG2MGG

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Materials Science Engineering Theses and Dissertations

Theses and Dissertations for the Materials Science Engineering department.
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