Single-phase lithium nickel oxides with the formula LiNi0.8Co0.2-2yTiyMgyO2
, y = 0.0-0.075 have been prepared and characterized. Their electrochemical
properties as cathode during charging and discharging are discussed. Therm
al behavior of the charged cathodes was studied by differential scanning ca
lorimetry (DSC). Results show that the cathodic behavior of compounds with
y = 0.0 and 0.03 and those with y = 0.05 and 0.075 are similar with respect
to the initial irreversible capacity, suppression of phase transitions, cy
cling behavior and capacity fading. The composition with y = 0.05 shows a c
athodic capacity of 130 mA h/g at the 0.5 C rate and 2.5-4.4 V voltage wind
ow with only 7% fading over 40 cycles. The thermal behavior of the charged
cathode with y = 0.05 is improved compared to y = 0.0 and 0.03. A qualitati
ve explanation for the observed cathodic behavior with various y values is
offered in terms of the occupancy of the magnesium-ions in the Li and Ni la
yers in the lattice. (C) 2001 Elsevier Science B.V. All rights reserved.