Enhanced Structural Stability and Cyclability of Al-Doped LiMn[sub 2]O[sub 4] Spinel Synthesized by the Emulsion Drying Method

Spinel 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 compounds by calcination of the emulsion-dried precursor at 850°C in air. The Al doping range in the spinel phase was much wider. Characteristic X-ray mapping for the 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 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.