Developing and Investigating a Fast and Controllable Prelithiation Method for Lithium-Ion Batteries

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.