Electrochemical Insertion of lithium into perovskite structure NbO2F

被引:6
作者
Bohnke, Claude [1 ]
Bohnke, Odile [1 ]
Fourquet, Jean Louis [1 ]
机构
[1] Univ Maine, Lab Fluorures, UPRES A CNRS 6010, F-72085 Le Mans, France
来源
MOLECULAR CRYSTALS AND LIQUID CRYSTALS SCIENCE AND TECHNOLOGY SECTION A-MOLECULAR CRYSTALS AND LIQUID CRYSTALS | 1998年 / 311卷
关键词
electrochemical insertion; impedance spectroscopy; oxide fluoride;
D O I
10.1080/10587259808042361
中图分类号
O7 [晶体学];
学科分类号
0702 ; 070205 ; 0703 ; 080501 ;
摘要
Electrochemical insertion of lithium into perovskite structure NbO(2)F has been investigated. Lithium insertion leads to a structural transformation from the initial cubic unit cell to the LiNbO(3)-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.
引用
收藏
页码:23 / 29
页数:7
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