Structural characterization of Mn-based materials using γ-MnOOH source

LiAl0.1Mn1.9O4 and LiMn2O4 materials were synthesized using LiOH, Al(NO3)(3), and different Mn sources (Mn3O4 and gamma -MnOOH). X-ray diffraction (XRD) showed that all prepared materials had, identical crystalline phase (cubic, Fd(3) over bar m). Two materials using the Mn3O4 source exhibited different cycling characteristics depending on the cycling voltage range. However, the two materials using the gamma -MnOOH source showed an identical cycling performance in both the 3 and 4 V regions. Transmission electron microscope analysis revealed that the materials using -y-MnOOH consisted of two kinds of structures of cubic and tetragonal in the resulting powders although they were shown as a pure cubic, spinet structure in the XRD diagram. This indicated a more stable state for the two Mn-based materials using gamma -MnOOH when the transformation from the cubic to tetragonal phase occurred in the 3 V region. (C) 2001 The Electrochemical Society.