Cathodic Characteristics of Amorphous Manganese Oxides as Lithium Secondary Battery

The amorphous manganese dioxides were prepared by reduction method using various reagents. The particle size and morphology depended on reducing agents, some of which were aggregated round particles of sub micron order, and the others were small fine fibers like of a few nm in width and several tens nm in length. The former showed low Li-insertion capacity of around 200 mAhg(-1), while the latter material showed high capacity of 500 mAhg(-1) in the OCV measurements until 1 V vs. Li. The as-prepared MnO2 contains some amount of water in the structure. The H2O-free MnO2 obtained by heat-treatment under high oxygen pressure was inferior in electrode property to MnO2 containing water in the structure. The H2O content related to the electrode performance.