Effects of aluminum on the structural and electrochemical properties of LiNiO2

LiNi1-yAlyO2 (0.10 less than or equal to y less than or equal to 0.50) compounds have been synthesized by a coprecipitation method. The characterization of the samples by X-ray and neutron diffraction, associated with Rietveld refinement analysis, has shown that for all materials, about 5% extra-nickel ions are present in the interslab space. Charge-discharge cycling of LiNi1-yAlyO2 as positive electrode material in lithium cells has shown that aluminum substitution suppresses all the phase transitions observed for the LiNiO, system. Good cycling stability was observed, but the capacity decreases from 125 to 100 mAh/g by increasing the aluminum amount from 10 to 25% (3-4.15 V range; C/20 rate). (C) 2003 Elsevier Science B.V. All rights reserved.