Li2MnSiO4 cathodes modified by phosphorous substitution and the structural consequences

Gummow, Rosalind J., Han, Guihong, Sharma, Neeraj, and He, Yinghe (2014) Li2MnSiO4 cathodes modified by phosphorous substitution and the structural consequences. Solid State Ionics, 259. pp. 29-39.

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Abstract

Li1.8MnSi0.8P0.2O4 prepared by a citrate acid assisted sol–gel route followed by calcination at 800 °C is compared to a sample of standard Li2MnSiO4 prepared under the same experimental conditions. The particle size of the P-substituted material is 20–40 nm compared to 50–100 nm for the P-free sample. Rietveld refinement of crystallographic models with synchrotron powder X-ray diffraction data shows that both samples consist of a mixture of the Pmn21 and Pmnb polymorphs of Li2MnSiO4 and a minor MnO impurity (< 5%). In the P-substituted material, P is found to partially replace Si in the Pmn21 polymorph accounting for the PO43 − bands observed in the FTIR spectra. The lattice parameters of the P-substituted material differ only slightly from those of the P-free material. Electrochemical tests show that Li/Li1.8MnSi0.8P0.2O4 cells have better performance than Li/Li2MnSiO4 cells in terms of reduced polarisation and a 66% better initial discharge capacity at 40 mA g− 1. P-substituted samples show some loss in long-range order with cycling but less than that observed in P-free samples. Significant reflections are observed in P-substituted cathode samples in the discharged state after the first cycle, in contrast to P-free material. This shows that P-substituted cathodes are less prone to amorphisation than standard P-free cathodes.

Item ID: 32206
Item Type: Article (Refereed Research - C1)
Keywords: lithium-ion battery; cathode; kinetics; phosphorus substitution; lithium manganese silicate
ISSN: 1872-7689
Funders: AINSE
Date Deposited: 20 Jun 2014 04:26
FoR Codes: 03 CHEMICAL SCIENCES > 0306 Physical Chemistry (incl Structural) > 030604 Electrochemistry @ 30%
03 CHEMICAL SCIENCES > 0306 Physical Chemistry (incl Structural) > 030606 Structural Chemistry and Spectroscopy @ 50%
03 CHEMICAL SCIENCES > 0303 Macromolecular and Materials Chemistry > 030306 Synthesis of Materials @ 20%
SEO Codes: 85 ENERGY > 8506 Energy Storage, Distribution and Supply > 850602 Energy Storage (excl. Hydrogen) @ 80%
97 EXPANDING KNOWLEDGE > 970110 Expanding Knowledge in Technology @ 20%
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