Pair distribution function analysis and Mossbauer study of defects in microwave-hydrothermal LiFePO(4)

Research Area: Uncategorized Year: 2012
Type of Publication: Article
Journal: RSC ADVANCES Volume: 2
Number: 1 Pages: 250-258
ISSN: 2046-2069
Olivine-type LiFePO(4) is nowadays one of the most important cathode materials of choice for high-energy lithium ion batteries. Its intrinsic defectivity, and chiefly the so-called lithium iron anti-site, is one of the most critical issues when envisaging electrochemical applications. This paper reports a combined diffractometric (Synchrotron Radiation XRD with Rietveld and PDF analyses) and spectroscopic (Mossbauer) approach able to give a thorough characterization of the material defectivity. Such analytical procedure has been applied to a sample prepared following an innovative microwave-assisted hydrothermal synthesis route that, in a few minutes, allowed us to obtain a well crystallized material. PDF analysis, which is applied for the first time to this type of battery material, reveals the presence of disorder possibly due to Li/Fe exchange or to a local symmetry lowering. A 5% amount of iron on the lithium site has been detected both by PDF as well as by Mossbauer spectroscopy, which revealed a small percentage of Fe(3+) on the regular sites.
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