An electrochemical impedance spectroscopy (EIS) study of three members of the family of compounds LixNi1-yCoyO2 (y ) 0, 0.2, and 1) has been performed by taking spectra at closely spaced bias potentials over the potential windows of utilization as cathodes in lithium-ion batteries. The spectra have been interpreted in terms of electronic and ionic transport properties. It has been found that, for x values greater than about 0.9, all the compounds show semiconductive properties with a specific resistance that increases with decreasing Ni content. For x close to about 0.9-0.8, the properties change into those of a metal-like material in which the ionic conductivity becomes the limiting factor. The transition between these two limiting conditions clearly appears in the impedance spectra.
Electronic and electrochemical properties of LixNi1-yCoyO2 cathodes studied by impedance spectroscopy
NOBILI, Francesco;MARASSI, Roberto
2001-01-01
Abstract
An electrochemical impedance spectroscopy (EIS) study of three members of the family of compounds LixNi1-yCoyO2 (y ) 0, 0.2, and 1) has been performed by taking spectra at closely spaced bias potentials over the potential windows of utilization as cathodes in lithium-ion batteries. The spectra have been interpreted in terms of electronic and ionic transport properties. It has been found that, for x values greater than about 0.9, all the compounds show semiconductive properties with a specific resistance that increases with decreasing Ni content. For x close to about 0.9-0.8, the properties change into those of a metal-like material in which the ionic conductivity becomes the limiting factor. The transition between these two limiting conditions clearly appears in the impedance spectra.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
