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Show simple item record Thackeray, MM Rossouw, MH Gummow, RJ Liles, DC Pearce, K De Kock, A David, WIF Hull, s 2007-06-08T06:38:53Z 2007-06-08T06:38:53Z 1993-06
dc.identifier.citation Thackeray, MM, et al. 1993. Ramsdellite-MnO2 for lithium batteries: The ramsdellite to spinel transformation. Electrochimica Acta, vol 38(9), pp 1259-1267 en
dc.identifier.issn 0013-4686
dc.description Copyright: 1993 Pergamon Press Ltd en
dc.description.abstract A pure and highly crystalline form of ramsdellite-MnO2 has been synthesized by acid treatment of the spinels LiMn2O4 and Li2Mn4O9 at 95°C. Although the ramsdellite-MnO2 framework remains intact on lithiation at 70°C, the hexagonally-close-packed oxygen array buckles towards a cubic-close-packed structure to accommodate the inserted lithium ions. The reaction is reversible but the instability of the structure on cycling limits the utility of ramsdellite-MnO2 as a rechargeable electrode in lithium cells. The ramsdellite structure can be stabilized by reaction with LiOH or LiNO3 at 300-400°C; this reaction, which displaces manganese ions from the MnO2 framework into interstitial octahedral sites generates spinel-related domains that coexist with the lithiated ramsdellite phase. At 300°C, under vacuum, the lithiated ramsdellite phase Li0.5MnO2 transforms to the spinel LiMn2O4; at 300-400°C, in air, it oxidizes slowly and transforms to a defect spinel LiMn2O4+delta (0 < delta < = 0.5) via an intermediate compound. A mechanism for the ramsdellite-spinel transition is proposed. en
dc.language.iso en en
dc.publisher Pergamon Press Ltd en
dc.subject Ramsdellite-MnO2 en
dc.subject Manganese dioxide en
dc.subject Lithium batteries en
dc.subject Electrochemistry en
dc.subject Sciences en
dc.title Ramsdellite-MnO2 for lithium batteries: The ramsdellite to spinel transformation en
dc.type Article en

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