%0 Journal Article
%A Sharma, Monika
%A Gupta, Mukul
%A Kaghazchi, Payam
%A Murugavel, Sevi
%T Size induced structural changes in maricite-NaFePO 4 : an in-depth study by experiment and simulations
%J Physical chemistry, chemical physics
%V 21
%N 45
%@ 1463-9084
%C Cambridge
%I RSC Publ.
%M FZJ-2019-06021
%P 25206 - 25214
%D 2019
%X Rechargeable batteries based on the most abundant elements, such as sodium and iron, have a great potential in the development of cost effective sodium ion batteries for large scale energy storage devices. We report, for the first time, crystallite size dependent structural investigations on maricite-NaFePO4 through X-ray diffraction, X-ray absorption spectroscopy and theoretical simulations. Rietveld refinement analysis on the X-ray diffraction data reveals that a decrease in the unit cell parameters leads to volume contraction upon reduction in the crystallite size. Further, the atomic multiplet simulations on X-ray absorption spectra provide unequivocally a change in the site symmetry of transition metal ions. The high resolution oxygen K-edge spectra reveal a substantial change in the bonding character with the reduction of crystallite size, which is the fundamental cause for the change in the unit cell parameters of maricite-NaFePO4. In parallel, we performed first-principles density functional theory (DFT) calculations on maricite-NaFePO4 with different sodium ion vacancy concentrations. The obtained structural parameters are in excellent agreement with the experimental observations on the mesostructured maricite-NaFePO4. The volumetric changes with respect to crystallite size are related to the compressive strain, resulting in the improvement in the electronic diffusivity. The nano-crystalline maricite-NaFePO4 with improved kinetics will open a new avenue for its usage as a cathode material in sodium ion batteries.
%F PUB:(DE-HGF)16
%9 Journal Article
%$ pmid:31696889
%U <Go to ISI:>//WOS:000506841300033
%R 10.1039/C9CP03838H
%U https://juser.fz-juelich.de/record/867204