Molten salt method of preparation and cathodic studies on layered-cathode materials Li(Co0.7Ni0.3)O2 and Li(Ni0.7Co0.3)O2 for Li-ion batteries

Layered compounds, Li(Co0.7Ni0.3)O-2 (I) and Li(Ni0.7Co0.3)O-2 (II) were prepared by molten salt method in temperature ranging from 650 to 950 degrees C. The effect of morphology, crystal structure and electrochemical properties of materials were evaluated by X-Ray Diffraction (XRD), Scanning Electron Microscopy and Brunauer-Emmett-Teller surface area, cyclic voltammetry (CV) and galvanostatic cycling. XRD pattern shows a hexagonal type structure with lattice parameters of a similar to 2.828 angstrom, c similar to 14.096 angstrom for I and a similar to 2.851 angstrom, c similar to 14.121 angstrom for II prepared in oxygen flow. The surface area of the compounds, I and II are 1.74 and 0.75 m(2) g(-1) respectively. CV studies show a main anodic peak occur at similar to 3.8-3.94 V vs. Li and a cathodic peak occur at similar to 3.6-3.7 V vs. Li. Galvanostatic cycling studies are carried out at a current rate of 30 mA g(-1) in the voltage range of 2.5-4.3 V, at room temperature. Li(Co0.7Ni0.3)O-2 prepared at 750 degrees C in air show a reversible capacity of 145 mAh g(-1) at the 1st discharge cycle and 13% capacity fading between 2 and 56 cycles, whereas Li(Ni0.7Co0.3)O-2 reheated in the presence of oxygen deliver a high and stable reversible capacity of 165 mAh g(-1) at the end of 60th cycle. (C) 2012 Elsevier B.V. All rights reserved.