Investigations on 0.5 Li ( Ni0.8Co0.15Zr0.05 ) O2 – 0.5 Li ( Li1 ∕ 3Mn2 ∕ 3 ) O2 Cathode for Li Rechargeable Batteries

Abstract

In the present work we have reported the electrochemical characteristics of 0.5–0.5 cathodes for lithium rechargeable batteries. In the pristine cathodes the formal oxidation state of Mn ions are , whereas Ni and Co are in the valence state. Rietveld refinement of the powders indicates a hexagonal layered structure (space group ) and minimal cation disorder between lithium and transition-metal layers. Raman analysis confirms the composite nature of pristine cathode laminates which contain (LMO)- and (LNCZO)-rich regions. The galvanostatic charge–discharge characteristic of these composite cathodes is reported in various cutoff voltage limits. When these composite cathodes are charged to , electrochemical extraction of Li takes place from active (LNCZO) as well as inactive (LMO) components. The charge and discharge capacitates of these cathodes are found to be due to , , and redox couples. Reasonably good cyclability of these composite cathodes is obtained when cycled in the cutoff voltage limits of . The cyclability of these composite cathodes are deteriorated when these composite cathodes are charged above and deep discharged up to , followed by repeated cycling in these voltage limits. The probable reasons for such findings are discussed.