Studies on bare and Mg-doped LiCoO2 as a cathode material for lithium ion batteries

Abstract

In this paper, we report on the preparation of bare and Mg-doped Li(Mg(subx(Co(sub1-x)O(sub2) (x = 0, 0.03, 0.05) phases by a molten salt method and their electrochemical properties. They were prepared at 800 C for 6 h in air. Rietveld refined X-Ray Diffraction data of bare (x = 0) and Mg-doped (x = 0.03, 0.05) compounds show a well-ordered hexagonal layer-type structure (a2.81A° , c14.05A° ). Scanning Electron Microscopy (SEM) show hexagonal type morphology at 800 C. Powder density was close to 5.02 gcm(sup-3), which compares well with the theoretical value. Electrochemical properties were studied in the voltage range of 2.5-4.3 V vs. Li using Cyclic Voltammetry (CV) and galvanostatic cycling. CV studies on bare and Mg-doped LiCoO(sub2) show main cathodic and anodic redox peaks at 3.9 V and4.0 V, respectively. Galvanostatic cycling of Li(Mg(subx)Co(sub1-x)O(sub2) (x = 0, 0.03, 0.05) showed reversible charge capacity values at the 60th cycle to be: 147 (±3) mAh(sup g-1) (x = 0), 127 (±3) mAh(sup g-1) (x = 0.03), and 131 (±3) mAh(sup g-1) (x = 0.05) cycled at a current density of 30 mA(sup g-1). Capacity retention is also favourable at 98.5%.