The insulator-metal transition upon lithium deintercalation from LiCoO2: electronic properties and 7Li NMR study

Samples of Li x CoO 2 (0.5≤x≤1) have been prepared by electrochemical deintercalation from high temperature LiCoO 2 and are characterized by X-ray diffraction, electrical measurements and 7 Li MAS NMR spectroscopy. X-Ray diffraction studies as a function of x are in good agreement with literature data and suggest that the two-phase domain for 0.75≤x≤0.94 is not due to structural reasons. Electrical conductivity and thermoelectronic power measurements evidence a gradual change in the electronic properties from localised to delocalised electrons upon lithium deintercalation. 7 Li MAS NMR suggests that the metal-non metal transition is the driving force for the existence of the biphasic domain.

[1]  Tsutomu Ohzuku,et al.  Solid‐State Redox Reactions of LiCoO2 (R3̅m) for 4 Volt Secondary Lithium Cells , 1994 .

[2]  J. Dahn,et al.  In situ x-ray diffraction and electrochemical studies of Li1−xNiO2 , 1993 .

[3]  M. Ichimura,et al.  Characterization and cathode performance of Li1 − xNi1 + xO2 prepared with the excess lithium method , 1995 .

[4]  C. Delmas,et al.  Cobalt segregation in the LiNi1−yCoyO2 solid solution: A preliminary 7Li NMR study , 1994 .

[5]  Tadeusz Bak,et al.  Modification in the electronic structure of cobalt bronze LixCoO2 and the resulting electrochemical properties , 1989 .

[6]  T. Matsue,et al.  In situ conductivity measurements of LiCoO2 film during lithium insertion/extraction by using interdigitated microarray electrodes , 1996 .

[7]  C. Delmas,et al.  6Li and 7Li NMR in the LiNi1-yCoyO2 Solid Solution (0 .ltoreq. y .ltoreq. 1) , 1995 .

[8]  J. Tarascon,et al.  CoO2, the end member of the LixCoO2 solid solution , 1996 .

[9]  J. Dahn,et al.  Electrochemical and In Situ X‐Ray Diffraction Studies of Lithium Intercalation in Li x CoO2 , 1992 .

[10]  Gerbrand Ceder,et al.  First-principles investigation of phase stability in Li x CoO 2 , 1998 .

[11]  J. Wit,et al.  The thermodynamic and thermoelectric properties of LixTiS2 and LixCoO2 , 1984 .

[12]  P. Hagenmuller,et al.  New families of cobalt substituted nickel oxyhydroxides and hydroxides obtained by soft chemistry , 1987 .

[13]  John B. Goodenough,et al.  LixCoO2 (0, 1980 .