Effect of manganese on the structural and thermal stability of Li0.3Ni0.7-yCo0.3-yMn2yO2 electrode materials (y=0 and 0.05)

Thermal and structural stabilities of Li0.3Ni0.7Co0.3O2 and Li0.3Ni0.65Co0.25Mn0.10O2 chemically delithiated cathode materials were studied by X-ray diffraction, thermogravimetric analysis and differential scanning calorimetry. The structure of the Li0.3Ni0.7Co0.3O2 layered material (S.C. R-3 m) transforms first to the spinel-type structure (S.C. Fd3m) and then to the completely disordered Ni0-type structure (S.C. Fm3m). These structural transitions were accompanied by 10.2% oxygen loss and leads to an exothermic reaction, activated by the electrolyte, more energetic than that of Li0.3Ni0.65Mn0.10O2 manganese substituted electrode. Furthermore, no structural changes were observed during the thermal treatment of Li0.3Ni0.65Co0.25Mn0.10O2 and relatively lower oxygen loss was recorded. The obtained results prove the positive effect of manganese substitution on the electrochemical features of Li0.3Ni0.7Co0.3O2. (C) 2011 Elsevier B.V. All rights reserved.