Structure and Electrochemistry of Li2Cr x Mn2 − x  O 4 for 1.0 ⩽ x ⩽ 1.5

Abstract

Li2CraMn2xO4 samples with x = 1.0, 1.25, and 1.5 were prepared by heating sol-gel precursors to elevated temperatures in argon. Three crystalline phases were observed as a function of the final heating temperature and x, and these were plotted on a structure-composition-temperature diagram. The samples lose some oxygen as they are heated, and this is probably part of the cause for the structural changes observed. The structure of Li2CrMnO4 heated to 1000 °C has been determined to be a distorted-hexagonal layered structure, much like that of the layered LiMnO2 phase recently reported by Armstrong and Bruce.'9 This does not agree with previous work by Davidson et al.," who claimed this phase was a tetragonal or orthorhombic distortion of the spinel structure. We show that Davidson's data are better explained by our model. At lower temperatures (e.g., 700 °C), the compounds are isostructural with LiCoO,, with the R-3m space group. Li/Li2CraJvln2_r04 electrochemical cells were made for all the samples and voltage-composition profiles measured. Li,Cr,25Mn,,,04 heated at 700 °C has an attractive voltage profile and a reversible capacity near 150 mAh/g when measured at a low rate of discharge.) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 155.69.4.4 Downloaded on 2014-11-05 to IP

Structural and electrochemical properties of LiNi1/3Co1/3Mn1/3O2 material prepared by a two-step synthesis via oxalate precursor

“…Since the introduction of rechargeable lithium-ion batteries as power sources for portable electronic devices, several positive electrode materials have been extensively investigated as alternatives to LiCoO 2 , which presents instability at potential above 4.2 V. To power hybrid electric vehicles, plug-in hybrid electric vehicles, and electric vehicles, researchers are looking for new materials capable to deliver high power density, higher reversible capacity, good cyclability, and safety [1][2][3]. Among the candidates, several compounds with a layered structure have been suggested, including LiNi 1−x CoO 2 [4,5] Li(Ni 1−x Co x ) 1−y Al y O 2 [6], LiNi 1/2 Mn 1/2 O 2 [6][7][8], LiNi x Mn x Co 1−2x O 2 (0≥x≥1/3) and its derivatives [9][10][11][12][13][14][15].…”

A study on insertion/removal kinetics of lithium ion in LiCrxMn2−xO4 by using powder microelectrode

“…However, its application is limited by its instability due to Jahn-Teller effect and dissolution of manganese into electrolyte during cycling of charging and discharge [6][7][8]. The problem can be solved to a great extent by substitution of other elements such as chromium, cobalt and nickel for a small fraction of manganese atoms in spinel lattice [9][10][11][12][13][14][15]. Much work has been done on preparation, structure and cyclic stability of doped spinel lithium manganese oxides, but less knowledge is available on the effect of doped elements on the kinetics of lithium insertion and removal in the spinel oxide, which is essential for the understanding of stability improvement and for the better application of doped lithium manganese oxide.…”

Electrochemical characterization of a new high capacity cathode

“…Pistoia et al [1] and Wang et al [2] were amongst the ®rst to demonstrate the use of chromium substituted manganese spinel phases as cathodes in secondary lithium cells. Compounds of formula Li 2 Cr x Mn 2Àx O 4 have been studied by Davidson et al [3,4] and by Dahn et al [5]. The experimental data from the latter publication was incorporated into a US patent issued to Dahn and Zheng [6].…”