Electroanalytical and thermal stability studies of multi-doped lithium nickel cobalt oxides

Lithiated nickel cobalt oxides are intensively being investigated for possible application in lithium batteries. Improving their electrochemical properties and thermal stability will enhance their chances for commercial application. In the present study, we report the electroanalytical and thermal properties of LiNi0.7Co0.2Ti0.05M0.05O2 (M = Al, Mg, Zn). Cyclic voltammetry experiments revealed the reversibility of the lithium intercalation processes. Impedance measurements showed a decrease in the charge transfer resistance as lithium extraction progressed. The Mg-doped system showed the best cyclability over 100 cycles, followed closely by the Al-doped system. Mg as a dopant led to improved thermal stability of the cathode material in the fully charged state. However, doping with Al or Zn resulted in reduced thermal stability. (C) 2003 Elsevier Science B.V. All rights reserved.