GEORGIA INSTITUTE OF TECHNOLOGY

Under the provisions of the regulations for the degree

DOCTOR OF PHILOSOPHY

on Monday, September 17, 2018

2:00 PM
in Love 109

will be held the

DISSERTATION PROPOSAL DEFENSE

for

Ah-Young Song

"Development of the high Lithium-ion crystalline Solid Electrolytes and understanding the ion dynamics"

Committee Members:

Dr. Gleb Yushin, Advisor, MSE

Dr. Angus Wilkinson, ChBE

Dr. Johannes Leisen, ChBE

Dr. Josh Kacher, MSE

Dr. Matthew McDowell, MSE

Abstract:

Li-rich antiperovskite studies were conducted to take into account the industrial needs of solid electrolytes in terms of lightweight, low-cost, low-processing temperature. Controversies surrounding previously reported studies motivated us to synthesize Li2+xOH1-x Hal (Hal = Cl and Br) with contaminant-free, ultra-fast, and well-controlled process. We carefully identified the compositions of the synthesized Li2+xOH1-xCl (0≤x<1) and Li2OHBr solid electrolytes and crystal structures at different temperatures. Our studies revealed the presence of proton in the prepared solid electrolytes compared to Li3OHal reported in previous studies. To characterize the materials, EDS, TOF-SIMS, NMR, XPS and XRD have been performed. The fraction of H, which is analyzed in the solid electrolytes, effects on Li ion conductivity inevitably. In contrast to the existing belief that the presence of H impedes Li ion hopping, we found that H should be involved in Li+ conduction mechanism. Since the Li ion conduction mechanism has not been investigated, fundamental understanding about Li ion dynamics will be performed with various approaches theoretically and experimentally.