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 degrees C for 6h 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 degrees C without severe capacity degradation. In particular, the LiAl0.08Mn1.92O4 sample demonstrates excellent capacity retention of 99.3% after 50 cycles at 55 degrees C, confirming the greatly enhanced electrochemical stability of LiMn2O4 by a small quantity of Al-doping. (c) 2008 Elsevier Ltd. All rights reserved.