The effects of sintering time on the structure and electrochemical properties of Li(Ni0.8Co0.2)O2

We present the findings of a new study on the effects of sintering time on the structure and electrochemical properties of layered Li(Ni0.8Co0.2)O-2. Fur this study, we have examined samples prepared with sintering times of 3, 24, 48 and 96 h. The structure was initially examined by powder X-ray diffraction and then more precisely by time of flight powder neutron diffraction, with structural analysis by the Rietveld method being performed. The structural analysis indicated differences in the Li 3a and Ni/Co 3b site occupancies, which appear to be related to the sintering times. Electrochemical charge/discharge measurements indicated that the initial discharge capacities for the samples prepared at 3, 24, and 48 h were basically invariant. However, a sizeable increase was noted for the sample prepared with a sintering time of 96 h. Also, an increase in the obtained discharge capacity from the first to second cycles was found for the samples prepared with 3-48 h sintering times. The largest increase was noted for the sample prepared for 48 h. No increase was seen for the sample sintered for 96 h. However, for all, samples examined in this work, the capacities on first discharge were in excess of 180 mA h/g. (C) 2000 Elsevier Science S.A, All rights reserved.