RIETVELD REFINEMENTS OF [[alpha]]-MnO₂ AND LITHIATED [[alpha]]-MnO₂ FROM NEUTRON DATA. M. F. Mansuetto, D. W. Dees, C. S. Johnson, M. M. Thackeray, D. W. Vissers, D. Argyriou, ^aL. Christensen, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439, ^a3M Corporation, 3M Center, Building 218-3CA-06, St. Paul, MN 55144

The structures of alpha manganese dioxide ([[alpha]]-MnO₂) and lithiated products have been refined from neutron data using the Rietveld method. [[alpha]]-MnO₂ was synthesized from alkaline battery grade [[gamma]]-MnO₂ via a two step reaction scheme and dehydrated by heat-treatment. [[alpha]]-MnO₂- was chemically and electrochemically lithiated. Neutron diffraction data from powder samples were collected on the Special Environment Powder Diffractometer (SEPD) of the Intense Pulsed Neutron Source facility (IPNS) at Argonne National Laboratory. Rietveld refinements were carried out using GSAS (General Structure Analysis System). The refinements confirm that it is possible to synthesize an anhydrous [[alpha]]-MnO₂- framework structure without any stabilizing cation in the large (2 x 2) channels. Structural stability to electrochemical cycling when lithium is inserted into, and extracted from the [[alpha]]-MnO₂ framework will be discussed.