Cathodic behavior of (Co, Ti, Mg)-doped LiNiO2

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.