A STUDY OF THE INFLUENCE OF OXYGEN DEFICIENCY ON LITHIUM ION DIFFUSIVITY IN CERIUM OXIDE

• Main Author: Waraney Moesa Komalig, Ravanny
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/69790
• Institution: Institut Teknologi Bandung

Cerium oxide is considered as a promising protective coating material for highenergy cathode of Li-ion battery against surface structural degradation. However, detailed knowledge on how Li migrates in cerium oxide is still limited, which is important for further development of cerium oxide as LIB high energy cathode coating material. Herein, using first-principles density functional theory (DFT) calculations, we investigate Li insertion and diffusion mechanism in pristine CeO2, reduced CeO2 with oxygen vacancy, and Ce2O3 as a representative material for highly reduced cerium oxide. For three different concentrations (1:1, 1:8 and 1:27 Li:Ce), we find that Li can occupy empty octahedral site of CeO2 in either neutral or ionized state. For two different concentrations (1:2 and 1:16 Li:Ce), Li intercalation is only spontaneous for ionized state in Ce2O3. Li diffusion in fluorite CeO2 is isotropic to ?110? direction and the energetic barrier is significantly high. An addition of O-vacancy in the CeO2 fluorite structure breaks the isotropy of Li diffusion; the barrier is decreased if the vacancy is located unidirectional with ?110? direction and the barrier is increased if it is in the opposite of ?110? direction. The diffusion barrier of Li in this structure is significantly lower compare to the previous pristine and reduced CeO2 in two different concentrations, i.e., 1:2 and 1:16 Li:Ce. This indicates that the degree of reduction highly correlates to Li diffusivity in cerium oxide. Therefore, applying highly reduced and O-poor CeO2 coating should be preferred to allow fast and non-obstructive Li diffusion.