Thackeray, MMRossouw, MHGummow, RJLiles, DCPearce, KDe Kock, ADavid, WIFHull, s2007-06-082007-06-081993-06Thackeray, MM, et al. 1993. Ramsdellite-MnO2 for lithium batteries: The ramsdellite to spinel transformation. Electrochimica Acta, vol 38(9), pp 1259-12670013-4686http://hdl.handle.net/10204/451Copyright: 1993 Pergamon Press LtdA 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.enRamsdellite-MnO2Manganese dioxideLithium batteriesElectrochemistrySciencesArticleThackeray, M., Rossouw, M., Gummow, R., Liles, D., Pearce, K., De Kock, A., ... Hull, s. (1993). Ramsdellite-MnO2 for lithium batteries: The ramsdellite to spinel transformation. http://hdl.handle.net/10204/451Thackeray, MM, MH Rossouw, RJ Gummow, DC Liles, K Pearce, A De Kock, WIF David, and s Hull "Ramsdellite-MnO2 for lithium batteries: The ramsdellite to spinel transformation." (1993) http://hdl.handle.net/10204/451Thackeray M, Rossouw M, Gummow R, Liles D, Pearce K, De Kock A, et al. Ramsdellite-MnO2 for lithium batteries: The ramsdellite to spinel transformation. 1993; http://hdl.handle.net/10204/451.TY - Article AU - Thackeray, MM AU - Rossouw, MH AU - Gummow, RJ AU - Liles, DC AU - Pearce, K AU - De Kock, A AU - David, WIF AU - Hull, s AB - 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. DA - 1993-06 DB - ResearchSpace DP - CSIR KW - Ramsdellite-MnO2 KW - Manganese dioxide KW - Lithium batteries KW - Electrochemistry KW - Sciences LK - https://researchspace.csir.co.za PY - 1993 SM - 0013-4686 T1 - Ramsdellite-MnO2 for lithium batteries: The ramsdellite to spinel transformation TI - Ramsdellite-MnO2 for lithium batteries: The ramsdellite to spinel transformation UR - http://hdl.handle.net/10204/451 ER -