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

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