Suppression of Phase Transitions in Li-rich Lithium Cobaltite Cathodes Observed by Microparticle Cyclic Voltammetry

The electrochemical behavior of several Li-rich electrodes has been examined by microparticle cyclic voltammetry. A 10 M NaOH solution has been shown to provide a convenient aqueous phase capable to simulate the routinely employed organic Li-ion electrolytes. The voltammetric spectra show that the intercalation process undergoes to significant modifications in the case of nonstoichiometric electrodes with a nominal Li/Co atomic ratio 1.08 and beyond. In these samples the irreversible phase transitions, which are commonly believed to be responsible for the capacity fading of stoichiometric Li cobaltite materials, are clearly inhibited. The suppression effect reaches a maximum for a Li/Co ratio equal to 1.10. © 2002 The Electrochemical Society. All rights reserved.