Enhanced electrochemical stability of Al-doped LiMn2O4 synthesized by a polymer-pyrolysis method

LiAlxMn2−xO4 samples (x = 0, 0.02, 0.05, 0.08) were synthesized by a polymer-pyrolysis method. The structure and morphology of the LiAlxMn2−xO4 samples calcined at 800 °C for 6 h were investigated by powder X-ray diffraction and scanning electron microscopy. The results show that all samples have high crystallinity, regular octahedral morphology and uniform particle size of 100–300 nm. The electrochemical performances were tested by galvanostatic charge–discharge and cyclic voltammetry. The results demonstrate that the Al-doped LiMn2O4 can be very well cycled at an elevated temperature of 55 °C without severe capacity degradation. In particular, the LiAl0.08Mn1.92O4 sample demonstrates excellent capacity retention of 99.3% after 50 cycles at 55 °C, confirming the greatly enhanced electrochemical stability of LiMn2O4 by a small quantity of Al-doping.