Capacity stabilization of layered Li_0.9Mn_0.9Ni_0.1O₂ cathode material by employing ZnO coating

Abstract

Li_0.9Mn_0.9Ni_0.1O₂ has been prepared by an ion-exchange process and evaluated as the positive electrode material for lithium-ion battery application. The particles of the oxide have been subjected to surface modification by coating a thin layer of ZnO. Both the ZnO coated and bare samples have been characterized by chemical analysis, powder X-ray diffraction, scanning electron microscopy, EDAX, EDS-dot mapping, cyclic voltammetry, charge-discharge cycling and AC impedance spectroscopy. The physicochemical studies suggest the formation of a layered structure in the oxide with a uniformly dispersed ZnO coating on fine particles. The electrochemical studies suggest a stable discharge capacity of 210 mA h g^-1 for ZnO coated oxide over about 50 cycles tested in the studies. By contrast, the capacity of bare oxide decreases rapidly on cycling. The enhanced performance of these electrodes is also reflected in AC impedance studies.