Theses and dissertations

This collection includes both ASU Theses and Dissertations, submitted by graduate students, and the Barrett, Honors College theses submitted by undergraduate students. 

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Mechanics of silicon electrodes in lithium ion batteries

Description
As one of the most promising materials for high capacity electrode in next generation of lithium ion batteries, silicon has attracted a great deal of attention in recent years. Advanced characterization techniques and atomic simulations helped to depict that the lithiation/delithiation of silicon electrode involves processes including large volume change…

As one of the most promising materials for high capacity electrode in next generation of lithium ion batteries, silicon has attracted a great deal of attention in recent years. Advanced characterization techniques and atomic simulations helped to depict that the lithiation/delithiation of silicon electrode involves processes including large volume change (anisotropic for the initial lithiation of crystal silicon), plastic flow or softening of material dependent on composition, electrochemically driven phase transformation between solid states, anisotropic or isotropic migration of atomic sharp interface, and mass diffusion of lithium atoms. Motivated by the promising prospect of the application and underlying interesting physics, mechanics coupled with multi-physics of silicon electrodes in lithium ion batteries is studied in this dissertation. For silicon electrodes with large size, diffusion controlled kinetics is assumed, and the coupled large deformation and mass transportation is studied. For crystal silicon with small size, interface controlled kinetics is assumed, and anisotropic interface reaction is studied, with a geometry design principle proposed. As a preliminary experimental validation, enhanced lithiation and fracture behavior of silicon pillars via atomic layer coatings and geometry design is studied, with results supporting the geometry design principle we proposed based on our simulations. Through the work documented here, a consistent description and understanding of the behavior of silicon electrode is given at continuum level and some insights for the future development of the silicon electrode are provided.
ContributorsAn, Yonghao (Author) / Jiang, Hanqing (Thesis advisor) / Chawla, Nikhilesh (Committee member) / Phelan, Patrick (Committee member) / Wang, Yinming (Committee member) / Yu, Hongyu (Committee member) / Arizona State University (Publisher)
Created2014

Determining Efficiency of Wastewater Treatment Plants' Energy Intensity

Description

Wastewater treatment plants (WWTP) are facilities with a large potential for energy savings and improvements, but the factors behind their efficiency remain largely unstudied. In this thesis, a limited study toward developing a benchmarking tool to allow comparison of operation of WWTPs in terms of energy intensity (EI) will be…

Wastewater treatment plants (WWTP) are facilities with a large potential for energy savings and improvements, but the factors behind their efficiency remain largely unstudied. In this thesis, a limited study toward developing a benchmarking tool to allow comparison of operation of WWTPs in terms of energy intensity (EI) will be analyzed. While the comparison of WWTPs is very complex, an initial start with comparing EI will be a useful tool. The methodology for this will first involve a literature review into EI at WWTPs to understand current statistics. After this, publicly available data gathered by Department of Energy sponsored Industrial Assessment Centers (IAC) from 2009 to 2021 of WWTP EI will be studied to show the potential for improvement of EI. This comparison can highlight certain states that currently exhibit more efficient plants, change in efficiency over time, as well as compare specific treatment technologies in literature to the general data gathered from the IAC. Lastly, the first step toward development of this benchmarking tool is a study of the 13 WWTP operations analyzed by the Arizona State University (ASU) IAC using a data envelopment analysis (DEA). This DEA can begin to show how a tool could be used with more data to accurately compare and benchmark a WWTP based on performances of similar WWTPs. This tool could allow operators a possibility of seeing how well their performance compares, and work toward an improvement in their EI.
ContributorsWickman, Sydney (Author) / Villalobos, Rene (Thesis director) / Phelan, Patrick (Committee member) / Gungor-Demirci, Gamze (Committee member) / Barrett, The Honors College (Contributor) / School of International Letters and Cultures (Contributor) / School of Sustainable Engineering & Built Envirnmt (Contributor)
Created2022-12