Role of iodine species in structural stability of nanocrystalline manganese oxyiodides

Micro-Raman and X-ray absorption spectroscopy have been applied to determine the geometric and electronic structures of X-ray amorphous manganese oxyiodide nanocrystals prepared in acetone or aqueous solutions. Manganese ions are stabilized commonly in layered lattice consisting of edge-shared MnO6 octahedra, while the oxidation state of iodine species is dependent on the reaction media. On the basis of the present experimental findings, prominent capacity loss of the anhydrous nanocrystals can be explained from the structural instability of layered lattice caused by the lack of IO3- cluster and/or by the partial substitution of oxide with iodide. (C) 2004 The Electrochemical Society.