Date of Award

August 2022

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Department

Engineering

First Advisor

Deyang Qu

Committee Members

Ilya Avdeev, Prasenjit Guptasarma, Yin Wang, Yongjin Sung

Keywords

Electrochemical impedance, Initial coulombic efficiency, Lithium-ion battery, Prelithiation, Solid electrolyte interface

Abstract

Prelithiation is to pre-load Li ions in a Li-ion electrode prior to a formation cycle. A chemical, roll-to-roll prelithiation method was developed in this thesis research. The method can be applied to different anode materials. The prelithiation compensated the initial loss of lithium during the formation cycles of a lithium-ion battery (LIB). Eventually, the initial coulombic efficiency (ICE) was significantly increased. In addition, the cyclability of a prelithiated battery was highly related to the quality of the solid electrolyte interface (SEI) on the anode surface. Electrochemical impedance spectroscopy (EIS) was a major technique to evaluate the difference of the SEI between a chemical lithiation and an electrochemical lithiation. An EIS analysis method was developed where the EIS data were transformed from a frequency domain into a time domain to identify the kinetics of each electrochemical process. An equivalent circuit to simulate the behavior of a battery is then created. By combining the simulation results and the cycling performance, a solid electrolyte interface was investigated quantitatively.

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