Enhanced structural stability and cyclability of Al-doped LiMn2O4 spinel synthesized by the emulsion drying method

Spinel LiMn2O4 oxide is of great interest as a low cost and environmentally kind intercalation cathode material for rechargeable lithium batteries, but has suffered from structural unstability during intercalation/deintercalation and severe capacity fading with cycling. Here, we successfully synthesized the spinel LiAlxMn2-xO4 compounds by calcination of the emulsion-dried precursor at 850 degrees C in air. The Al doping range in the spinel phase was much wider. Characteristic X-ray mapping for the LiAl0.3Mn1.7O4 confirmed that Al and Mn were uniformly distributed throughout the crystalline oxide particles. The interaction energy between lithium positive-positive ions for lithium insertion in the host structure remarkably increased with Al doping, and the x value between 0.2 and 0.3 in LiAlxMn2-xO4 was a critical point for showing a simple potential variation. Al-doped samples exhibited excellent cyclablility with showing relatively higher discharge capacity retention due mainly to the stabilized structure as well as the reduced strain during repeated intercalation/deintercalation of lithium by Al substitution. (C) 2001 The Electrochemical Society.