The influence of doping on the operation of lithium manganese oxide spinel

LiMn2O4 and LiMn2 − xCoxO4 (0.1 ≤ x ≤ 0.4) samples were prepared by a precipitation technique followed by an appropriate heat treatment in the 600–800 °C temperature range. The spinel materials were characterized by powder X-ray diffraction and electrochemical measurements. The differential capacity versus voltage plots indicate that the presence of cobalt strongly influences the order/disorder phase transition of the inserted lithium ions in the upper potential region of the spinel phase. This can be proven by X-ray diffraction measurements of delithiated spinels, showing two coexisting spinel phases in the undoped system whereas a single phase behavior in the cobalt-doped spinel system is observed. These materials show excellent capacity retention during extended cycling.