Hydrothermal Synthesis of Lithium Manganese Oxide with .ALPHA.-NaFeO2 Structure.

Abstract

Hydrothermal synthesis of lithium manganese oxide with α-NaFeO2 structure has been studied. A LixMnO2⋅nH2O, (Li-birnessite), with rhombohedral symmetry was used as a starting material. When the molar ratio of Mn/Al was smaller than 0.9/0.1, spinel type lithium manganese oxides were obtained. On the other hand, when the molar ratio of Mn/Al was larger than 0.85/0.15, metastable lithium manganese oxides with α-NaFeO2 structure formed at 80°C, and the capacity fade of the Li-ion cell with cathodes made of these oxides was very small in comparison with that of cathodes made of layered Li-manganese oxides, as previously reported.