Structural and electrochemical studies of alpha manganese dioxide ((alpha)-MnO(sub 2))

摘要

The structural and electrochemical properties of alpha-MnO(sub 2), prepared by acid digestion of Mn(sub 2)O(sub 3), and its lithiated derivatives xLi(sub 2) O . MnO(sub 2) (where x is greater than or equal to zero and less than or equal to 0.25) have been investigated as insertion compounds in the search for new and viable cathode materials for rechargeable 3-V batteries. The alpha-MnO(sub 2) product fabricated by this technique contains water within the large (2x2) channels of the structure; the water can be removed from the alpha-MnO(sub 2) framework without degradation of the structure, and then at least partially replaced by Li(sub 2)O. The lithia-doped alpha-MnO(sub 2) electrodes, described generically as xLi(sub 2)O . Mno(sub 2), stabilize the structure and provide higher capacities on cycling than the parent material. The structures of these alpha- MnO(sub 2)-type electrode materials are described. and electrochemical data are presented for both liquid electrolyte and polymer electrolyte Li/alpha-MnO(sub 2) and Li/xLi(sub 2)O . MnO(sub 2) cells.