Pair distribution function analysis and Mössbauer study of defects in microwave-hydrothermal LiFePO₄

Abstract

Olivine-type LiFePO 4 is nowadays one of the most important cathode materials of choice for highenergy 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 (Mö ssbauer) 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 Mö ssbauer spectroscopy, which revealed a small percentage of Fe 3+ on the regular sites.

Antisite Defects in Sol‐Gel‐Synthesized LiFePO4 at Higher Temperature: Effect on Lithium‐Ion Diffusion

“…also found the similar results about the antisite defects . The concentration and distribution of antisite defects observed by experimental procedures are in the range of 1–10 %, depending on different experimental conditions, such as the synthesis route, particle size, and temperature ,,…”

“…Moreover, antisite defects are possible in the LiFePO 4 at higher temperature if sufficient calcination time and required inert gas atmosphere are not available during calcination. Though, exact reason of defects formation in LiFePO 4 is still not clear, but according to previous studies reported,,,, there are many factors viz. calcination time, temperature, synthesis process etc.…”

Supercapacitive carbon nanotube-cobalt molybdate nanocomposites prepared via solvent-free microwave synthesis

“…Microwave synthesis has emerged as an important technique for preparing materials, offering higher reaction rates, better selectivities and shorter reaction time compared to conventional thermal methods. [25][26][27][28][29] Though several kinds of nanoscale molybdates have been successfully synthesized using this technique, 30,31 the reported methods involve utilizing a solvent.…”

New materials for Li-ion batteries: synthesis and spectroscopic characterization of Li2(FeMnCo)SiO4 cathode materials

“…Since the standard fitting procedure based on Lorentzian profiles and linear approximation generally leads to erroneous evaluation of weak and/or poorly resolved contributions4546, we chose to express the spectra line shape through the transmission integral function44 in order to take simultaneously all the broadening/distortion effects into account47.…”