Long-cycling coated LiCoO2 cathodes for lithium batteries - A review

The improved cycling properties of LiCoO2 cathodes are reviewed in this article. Three methods of coating: sol-gel, precipitation and mechano-thermal, are discussed. Both simple oxides such as Al2O3, SiO2, TiO2, ZrO2, etc.and mixed oxides such as MgAl2O4 and ZrTiO4 are compared as coating materials and, where possible, studies of nanomaterial coatings of the above are incorporated. Additionally, there is a brief comparison of the sol-gel and mechano-thermal coating methods. Structural data and morphology of the oxide coated cathodes are correlated with electrochemical behaviour. The enhanced cyclability is attributed to the suppression of cycle-limiting phase transitions. When a strong thin film of nanomaterial coating prevents the cathode from expanding structurally and dissolving into the electrolyte, cyclability is substantially enhanced. Furthermore, mixed oxide-coated cathodes demonstrate greater cyclability than corresponding individual oxide-coated cathodes. Using Al2O3 as an example, the effect of precursor selection for the coating oxide on the cyclability of the coated cathodes is also discussed