Date of Graduation

Fall 2017

Degree

Master of Science in Materials Science

Department

Physics, Astronomy, and Materials Science

Committee Chair

Ridwan Sakidja

Keywords

diffusion, density functional theory, nudge elastic band, ab-initio molecular dynamics, Li-ion battery, solid state electrolyte

Subject Categories

Materials Science and Engineering

Abstract

I have investigated the diffusion mechanisms of Li-ion in amorphous lithium phosphite (LiPO3) with addition of sulphur. By applying the nudge elastic band (NEB) method in crystal LiPO3 and Li3PO4, I confirmed the easing of diffusion pathways for Li ion in LiPO3 which is consistent with the previous theoretical finding[1]. From the diffusion study in 0.5 Li2O- 0.5 P2O5 and 0.4 Li2SO4 – 0.6 (Li2O-P2O5) melts above 3000K performed with ab-initio molecular dynamics (AIMD), produces identical outcome as experimental at lower temperatures. I demonstrated the benefit of addition of S in increasing Li+ mobility. I also found that the Li2SO4 addition into the glass results in a characteristic shift in Li-ion vibration to a lower vibrational frequency. In addition, the presence of oxygen surrounding the diffusion pathways appears to be essential in assisting the Li+ mobility in both crystalline and amorphous structures. The activation energy barrier shows similar pattern as reported in experimental analysis with LiPO3[2].

Copyright

© Md Shafiqul Islam

Available for download on Monday, December 31, 2018

Open Access

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