In Situ X‐Ray Absorption Fine Structure Studies of a Manganese Dioxide Electrode in a Rechargeable MnO2 / Zn Alkaline Battery Environment

Electronic and structural aspects of a MnO{sub 2} electrode in a rechargeable MnO{sub 2}/Zn battery environment have been investigated by in situ Mn K-edge x-ray absorption fine structure (XAFS). The relative amplitudes of the three major Fourier transform shells of the extended XAFS function of the rechargeable MnO{sub 2} electrode in the undischarged state were similar to those found for ramsdellite, a MnO{sub 2} polymorph with substantial corner-sharing linkages among the basic MnO{sub 6} octahedral units. The analyses of the background-subtracted pre-edge peaks and absorption edge regions for the nominally 1-e{sup {minus}} discharged electrode were consistent with Mn{sup 3+} as being the predominant constituent species, rather than a mixture of Mn{sup 4+} and Mn{sup 2+} sites. Furthermore, careful inspection of both the x-ray absorption near edge structure and EXAFS indicated that the full recharge of MnO{sub 2}, which had been previously discharged either by one or two equivalent electrons, generates a material with decreased corner-sharing linkages compared to the original undischarged MnO{sub 2}.