Synthesis, structure, and electrochemical performance of magnesium-substituted lithium manganese orthosilicate cathode materials for lithium-ion batteries

Gummow, R.J., Sharma, N., Peterson, V.K., and He, Y. (2012) Synthesis, structure, and electrochemical performance of magnesium-substituted lithium manganese orthosilicate cathode materials for lithium-ion batteries. Journal of Power Sources, 197. pp. 231-237.

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Abstract

Magnesium-substituted lithium manganese orthosilicate (Li2MnSiO4) cathode materials with a nominal composition of Li2MgxMn1−xSiO4, for x = 0.4 and 0.5 are synthesized by a solid-state route, at 700 °C in argon. The samples are characterized using powder X-ray and neutron diffraction, scanning electron microscopy, and galvanostatic cell-cycling. Rietveld analyses of the powder X-ray and neutron diffraction data show the formation of a monoclinic P21/n structure related to gamma lithium phosphate with no significant impurity peaks. This structure of the Mg-substituted samples is in contrast to the unsubstituted Li2MnSiO4 compound that has a Pmn21 structure when synthesized under the same conditions. Unit-cell volumes of the Mg-substituted materials are intermediate between those of the P21/n structure of Li2MnSiO4 and the isostructural low-temperature form of Li2MgSiO4, indicating the formation of a solid solution. The Mg-substituted materials feature mixed Mg/Mn cation sites, although no evidence of Li/Mn, Li/Mg or Li/Mg/Mn mixed sites are found. The Li2MgxMn1−xSiO4 cathodes show improved electrochemical performance over that reported for the unsubstituted Li2MnSiO4P21/n phase. The Li2MgxMn1−xSiO4 cathode performance remains limited by its poor electronic properties and the large particle size of the solid-state synthesized products. Optimization of the synthesis conditions is likely to lead to enhanced electrochemical performance.

Item ID: 18863
Item Type: Article (Refereed Research - C1)
Keywords: magnesium substitution; solid solution; Rietveld refinement; neutron diffraction; x-ray diffraction; lithium manganese silicate
ISSN: 1873-2755
Date Deposited: 16 Mar 2012 05:47
FoR Codes: 03 CHEMICAL SCIENCES > 0302 Inorganic Chemistry > 030206 Solid State Chemistry @ 30%
09 ENGINEERING > 0912 Materials Engineering > 091205 Functional Materials @ 70%
SEO Codes: 85 ENERGY > 8506 Energy Storage, Distribution and Supply > 850602 Energy Storage (excl. Hydrogen) @ 100%
Citation Count from Web of Science Web of Science 2
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