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Title: Defect generation in TiO 2 nanotube anodes via heat treatment in various atmospheres for lithium-ion batteries
In this paper, ordered TiO 2 nanotubes were grown on a Ti substrate via electrochemical anodization and subsequently annealed at 450 °C for 4 h under various atmospheres to create different point defects. Oxygen-deficient environments such as Ar and N 2 were used to develop oxygen vacancies, while a water vapor (WV) atmosphere was used to generate titanium vacancies. Computational models by density functional theory predicted that the presence of oxygen vacancies would cause electronic conductivity to increase, while the presence of Ti vacancies could lead to decreased conductivity. The predictions were confirmed by two-point electrical conductivity measurements and Mott–Schottky analysis. Raman spectroscopy was also conducted to confirm the presence of defects. The annealed samples were then evaluated as anodes in lithium-ion batteries. The oxygen-deficient samples had an improvement in capacity by 10% and 25% for Ar- and N 2 -treated samples, respectively, while the WV-treated sample displayed a capacity increase of 24% compared to the stoichiometric control sample (annealed in O 2 ). Electrochemical impedance spectroscopy studies revealed that the WV-treated sample's increased capacity was a consequence of its higher Li diffusivity. The results suggest that balanced electrical and ionic conductivity in nanostructured metal oxide anodes can be tuned through defect generation using heat treatments in various atmospheres for improved electrochemical properties.  more » « less
Award ID(s):
1658076
PAR ID:
10084529
Author(s) / Creator(s):
; ; ; ; ; ; ; ; ;
Date Published:
Journal Name:
Physical Chemistry Chemical Physics
Volume:
20
Issue:
35
ISSN:
1463-9076
Page Range / eLocation ID:
22537 to 22546
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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