Synthesis, structure and electrochemistry of LiMn2-yAlyO4 prepared by a wet-chemistry method

The LiMn2-yAlyO4 spinel phases have been synthesised by wet-chemistry techniques using a methanolic solution of the metal acetates and dicarboxylic acid as a complexing agent. The formation temperature of LiMn2-yAlyO4 powders has been found to be as low as 350 degreesC using the succinic acid method. The physical properties of the synthesised products have been investigated by X-ray diffraction, Raman spectroscopy, thermal analyses, and electrical conductivity. To improve the rechargeable capacity of Li//LiMn2O4 cells, the electrochemical performances of LiMn2-yAlyO4 compounds as positive electrodes have been evaluated. The structural properties of the materials are very similar to LiMn2O4, the electrochemical performances show that the capacity is maintained at 95% of the initial value at the 50th cycle, this being explained by the change of the Mn3+/Mn4+ ratio in doped phases.