Gattu, Bharat
(2021)
A Fundamental Study of Nanostructured Si Anodes for Lithium Ion Batteries.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
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Abstract
Lithium-ion (Li-ion) batteries have emerged as the flagship, ubiquitous energy storage systems for portable / stationary consumer electronic devices such as video cameras, laptops, mobile phones including the plug-in hybrid as well as in the current models of all electric vehicles (EVs). Despite the commercialization of the first prototype Li-ion battery in 1990 by Sony, commercial Li-ion battery systems currently still employ graphite/carbon having a theoretical capacity of ~372 mAh/g as the anode system. Silicon exhibits a theoretical capacity of ~4200 mAh/g and is explored as a promising anode to replace graphite in LIBs. However, silicon undergoes huge volume expansion (>300%) during lithium alloying / de-alloying resulting, in tremendous crystallographic related phase induced stresses. As a result of these stresses, there is pulverization of the active material in the electrodes resulting in loss of electronic contact with the substrate/current collector resulting in drastic and rapid reduction in capacity and subsequently, the failure of the battery.
In this work, different synthesis approaches (electrodeposition, electroless plating, hydrothermal synthesis, chemical vapor deposition, high energy mechanical milling) for generating nanoscale Si and/or Si composite nanostructures, such as (1) silicon-carbon core-shell (C@Si@C) hollow nanotubes, (2) silicon nanorods and silicon nanoflakes, (3) electrodeposition of silicon thin films and (4) Si/VACNTs directly grown on Cu serving as binder-less system, are discussed. Their electrochemical behavior has been analyzed and correlated to the synthesis process, ensuing structural changes, related structural and microstructural property, degradation mechanism and finally their performance. The Si anodes were characterized for their structure, microstructure and electrochemical performance (first cycle irreversible loss, specific charge – discharge capacities, fade rate) in Li/Li+ system. Their behavior was correlated to morphology of nanostructures before and after electrochemical cycling, and process parameters employed during the synthesis process. X-Ray diffraction, Raman spectroscopy, SEM/TEM, BET analysis and XPS have been used to characterize the crystallographic structure and composition of these nanostructures before and after electrochemical cycling to confirm the evolution, phase and morphological stability of these nanostructures. Subsequently, effort has been made to analyze and study the electrochemical response in full cell system using LiNMC111 at critical loadings using CC-CV mode of testing.
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Details
| Item Type: |
University of Pittsburgh ETD
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| Status: |
Unpublished |
| Creators/Authors: |
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| ETD Committee: |
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| Date: |
26 January 2021 |
| Date Type: |
Publication |
| Defense Date: |
5 November 2020 |
| Approval Date: |
26 January 2021 |
| Submission Date: |
21 October 2020 |
| Access Restriction: |
No restriction; Release the ETD for access worldwide immediately. |
| Number of Pages: |
308 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Swanson School of Engineering > Chemical and Petroleum Engineering |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
chemical vapor deposition, electrospinning, electroplating, electrodeposition, hydrothermal, thin film, mechanical milling, nanotube, nanoflake, nanorod, core shell, electrochemistry, Plasma enhanced chemical vapor deposition, vacuum chemical vapor deposition, Li metal plating |
| Related URLs: |
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| Date Deposited: |
26 Jan 2021 21:26 |
| Last Modified: |
26 Jan 2021 21:26 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/39803 |
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