3-VOLT MANGANESE-DIOXIDE - THE AMORPHOUS ALTERNATIVE

New alkaline manganese dioxides were prepared via a single step soft c hemistry route, by varying the preparation conditions to adjust the Mn oxidation state. Li capacities as high as 0.85 Li per manganese atom were achieved for some formulations. The lithiated materials, under an initial charge, display a topotactic type reaction within the 2-4.5 V voltage range during the Li (de-)intercalation process, in comparison to the discontinuity in the 3-4 V plateau regions for LiMn2O4 spinel cycling. A slight conversion to the spinel response, however, was obse rved for materials heated at 300 degrees C. Samples heated at lower te mperatures do not exhibit the spinel conversion and provide, in most c ases, an appreciable electrochemical response at high cycling rates. T his is exemplified by Li0.37K0.01MnO2.01, with a specific capacity of 160 mAh g(-1) at C/1.8 (85 mA g(-1)).