Influence of Cobalt Ions on the Electrochemical Properties of Lamellar Manganese Oxides

Evaluation of Co-doping on the electrochemical properties of the sol-gel birnessite and the new lithiated manganese oxide Li(0.45)MnO(2+delta) is reported. For both compounds the synthesis of Co-doped materials via a solution technique is described. We demonstrate the interest of Co-doped structures with the selected content of 0.15 Co per mole of oxide as the optimum composition. In the case of Li(0.45)Mn(1-y)CO(y)O(2+delta), prepared at 300 degrees C a mixture of a lamellar phase and a cubic one is identified while the Co-doped birnessite appears as a single phase. A probable substitution of Mn by Co ions explains the better specific capacity of 185 mAh/g found and the excellent stability observed over 40 cycles in the voltage range 4.2-2.0 V.