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

Samples of LixCoO2(0.5 less than or equal to x less than or equal to 1) hav e been prepared by electrochemical deintercalation from high temperature Li CoO2 and are characterized by X-ray diffraction, electrical measurements an d Li-7 MAS NMR spectroscopy. X-Ray diffraction studies asa function of x ar e in good agreement with literature data and suggest that the two-phase dom ain for 0.75 less than or equal to x less than or equal to 0.94 is not due to structural reasons. Electrical conductivity and thermoelectronic power m easurements evidence a gradual change in the electronic properties from loc alised to delocalised electrons upon lithium deintercalation. Li-7 MAS NMR suggests that the metal-non metal transition is the driving force for the e xistence of the biphasic domain.