Nanoparticulate coatings for enhanced cyclability of LiCoO2 cathodes

Surface modification as a method for enhancing the cyclability of LiCoO2 cathodes is reviewed. The performances of TiO2 and ZrO2, and their mixed oxide, ZrTiO4, as coating materials, are compared. Coating techniques such as sol-gel and mechano-thermal processes are described. Structural data and morphology of the oxide-coated LiCoO2 are correlated with electrochemical behavior. Their enhanced cyclability is attributed to the suppression of the cycle-limiting phase transitions accompanying the charge-discharge processes. The higher cyclability of the mixed oxide-coated cathodes over those coated with the corresponding individual oxides is also demonstrated. It is also shown that the nature of the core material and the sol-gel precursors for the coatings play a definitive role in the electrochemical behavior of the coated cathode materials.