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Titolo:
RAMSDELLITE-MNO2 FOR LITHIUM BATTERIES - THE RAMSDELLITE TO SPINEL TRANSFORMATION
Autore:
THACKERAY MM; ROSSOUW MH; GUMMOW RJ; LILES DC; PEARCE K; DEKOCK A; DAVID WIF; HULL S;
Indirizzi:
CSIR,DIV MAT SCI & TECHNOL,POB 395 PRETORIA 0001 SOUTH AFRICA RUTHERFORD APPLETON LAB DIDCOT OX11 0QX OXON ENGLAND
Titolo Testata:
Electrochimica acta
fascicolo: 9, volume: 38, anno: 1993,
pagine: 1259 - 1267
SICI:
0013-4686(1993)38:9<1259:RFLB-T>2.0.ZU;2-5
Fonte:
ISI
Lingua:
ENG
Soggetto:
ELECTROLYTIC MANGANESE-DIOXIDE; SECONDARY LI CELLS; NONAQUEOUS CELL; ELECTROCHEMICAL CHARACTERIZATION; OXIDES; REDUCTION;
Keywords:
RAMSDELLITE; SPINEL; MANGANESE DIOXIDE; STRUCTURE; LITHIUM BATTERIES;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
29
Recensione:
Indirizzi per estratti:
Citazione:
M.M. Thackeray et al., "RAMSDELLITE-MNO2 FOR LITHIUM BATTERIES - THE RAMSDELLITE TO SPINEL TRANSFORMATION", Electrochimica acta, 38(9), 1993, pp. 1259-1267

Abstract

A pure and highly crytalline form of ramsdellite-MnO2 has been synthesized by acid treatment of the spinels LiMn2O4 and Li2Mn4O9 at 95-degrees-C. Although the ramsdellite-MnO2 framework remains intact on lithiation at 70-degrees-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-degrees-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-degrees-C, under vacuum, the lithiated ramsdellite phase Li0.5MnO2 transforms to the spinel LiMn2O4; at 300-400-degrees-C, in air, it oxidizes slowly and transforms to a defect spinel LiMn2O4+delta (0 < delta less-than-or-equal-to 0.5) via an intermediate compound. A mechanism for the ramsdellite-spinel transition is proposed.

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Documento generato il 25/11/20 alle ore 18:31:12