An investigation on layered birnessite type manganese oxides for battery applications

Layered birnessite-type manganese oxide was prepared by a simple redox sol- gel reaction involving hydroxylamine and permanganate in alkaline medium. I R, XRD, Auger electron spectroscopy, EPR, TGA and cyclic voltammetric chara cteristics of the birnessites are presented. The birnessite was examined fo r its cathode performance in zinc-, magnesium- and lithium-based cells. Bis muth and lead exchanged birnessite show superior battery performance when c ompared with sodium and potassium precursors. The magnetoresistance pattern of the discharged birnessite (in Mg/Mg(ClO4)(2)) indicates a colossal magn etoresistance, This observation provides a scope for further studies of exa mining the applicability of magnetoresistance measurement in assessing the charge/discharge status of manganese oxides. Heat treatment of birnessite b rings about distinct changes in the EPR and IR pattern. A correlation betwe en the spectral features and electrochemical activity can be understood. (C ) 2000 Elsevier Science S.A. All rights reserved.