Electrochemical Insertion of lithium into perovskite structure NbO2F
作者:
Claude Bohnke,
Odile Bohnke,
JeanLouis Fourquet,
期刊:
Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals
(Taylor Available online 1998)
卷期:
Volume 311,
issue 1
页码: 23-29
ISSN:1058-725X
年代: 1998
DOI:10.1080/10587259808042361
出版商: Taylor & Francis Group
关键词: electrochemical insertion;impedance spectroscopy;oxide fluoride
数据来源: Taylor
摘要:
Electrochemical insertion of lithium into perovskite structure NbO2F has been investigated. Lithium insertion leads to a structural transformation from the initial cubic unit cell to the LiNbO3-type structure which presents a hexagonal symmetry. The maximum lithium uptake is 1.2 Li/Nb at room temperature. It corresponds to 60% of the expected maximum. Insertion has been followed by discharge experiments associated with impedance spectroscopy. The experimental results show that the electrochemical process can be characterized by an electrode reaction - layer formation - diffusion sequence. An equivalent circuit model which includes charge transfer reaction, layer formation, constant phase elements and diffusion impedance is proposed. The mechanism of insertion is discussed on the basis of the crystallographic structure of the perovskite. The layer may be viewed as a shell of a high inserted compound surrounding a relatively unaffected nucleus which is formed as insertion proceeds.
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