کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1286487 | 1497969 | 2014 | 6 صفحه PDF | دانلود رایگان |
• The carbon-hybridized Li2MnSiO4 nanostructured powders show the stable cycling performance with a capacity of ∼190 mAh g−1.
• HE-XRD and PDF analyses were carried out to study the discharged/charged structures.
• A long-range ordered structure dissipates in the discharged samples but each discharging process recovers it.
• The disappearance of the long-range order is caused by a local structure accommodating distortions of the MnO4 tetrahedra.
The stable cycling performance with a high discharge capacity of ∼190 mAh g−1 in a carbon-hybridized Li2MnSiO4 nanostructured powder has prompted an experimental investigation of the charged/discharged structures using synchrotron-based and laboratory-based X-rays and atomic-pair distribution-function (PDF) analyses. A novel method of in-situ spray pyrolysis of a precursor solution with glucose as a carbon source enabled the successful synthesis of the carbon-hybridized Li2MnSiO4 nanoparticles. The XRD patters of the discharged (lithiated) samples exhibit a long-range ordered structure characteristic of the (β) Li2MnSiO4 crystalline phase (space group Pmn21) which dissipates in the charged (delithiated) samples. However, upon discharging the long-range ordered structure recovers in each cycle. The disordered structure, according to the PDF analysis, is mainly due to local distortions of the MnO4 tetrahedra which show a mean Mn–O nearest neighbor distance shorter than that of the long-range ordered phase. These results corroborate the notion of the smaller Mn3+/Mn4+ ionic radii in the Li extracted phase versus the larger Mn2+ ionic radius in Li inserted phase. Thus Li extraction/insertion drives the fluctuation between the disordered and the long-range ordered structures.
Journal: Journal of Power Sources - Volume 263, 1 October 2014, Pages 7–12