STRUCTURAL AND ELECTROCHEMICAL STUDIES OF ALPHA-MANGANESE DIOXIDE (ALPHA-MNO2)

The structural and electrochemical properties of alpha-MnO2, prepared by acid digestion of Mn2O3, and its lithiated derivatives xLi(2)O . Mn O2 (0 less than or equal to x less than or equal to 0.25) have been in vestigated as insertion compounds in the search for new and viable cat hode materials for rechargeable 3 V batteries. The alpha-MnO2 product fabricated by this technique contains water within the large (2 x 2) c hannels of the structure; the water can be removed from the alpha-MnO2 framework without degradation of the structure, and then at least par tially replaced by Li2O (lithium oxide). The Li2O-doped alpha-MnO2 ele ctrodes, described generically as xLi(2)O . MnO2, stabilize the struct ure and provide higher capacities on cycling than the parent material, The structures of these alpha-MnO2-type electrode materials are descr ibed, and electrochemical data are presented for both liquid electroly te and polymer electrolyte Li/alpha-MnO2 and Li/xLi(2)O . MnO2 cells. (C) 1997 Published by Elsevier Science S.A.