Chemically oxidized manganese dioxides for lithium secondary batteries

摘要

The specific discharge capacity of γ-MnO_2 was improved with chemical oxidation and vacuum-drying processes. The intergrowth structure and electrochemical performance were studied by X-ray diffraction and electrochemical measurements; the structure-electrochemical property relationships were clarified. Vacuum-dried γ-MnO_2 showed structural changes with capacity fade as the temperature increased, while the chemically oxidized γ-MnO_2 showed no structural change without any capacity fading. The latter material showed a first discharge capacity of 275 mAh g~(-1), and a reversible capacity of 250 mAh g~(-1) with two discharge plateaux after second cycle, which is the highest capacity among the γ-MnO_2 prepared previously.