Fast determination of phases in LiFePO4 using low losses in electron energy-loss spectroscopy

TL;DR

This paper presents a rapid method for identifying phases in LiFePO4 using low-loss electron energy-loss spectroscopy, supported by first-principles calculations, enabling quick phase determination and future dynamic studies.

Contribution

It introduces a novel approach combining VEELS measurements with first-principles calculations to distinguish phases in LiFePO4 efficiently.

Findings

Identification of a large peak in FePO4 spectrum absent in LiFePO4

Peak intensity is robust against crystal orientation

Method differentiates solid solution and two-phase regions

Abstract

Experimental valence electron energy loss spectra (VEELS), up to the Li K edge, obtained on different phases of LixFePO4 are compared to first principles calculations using the density functional code WIEN2k. In the 4-7 eV range, a large peak is identified in the FePO4 spectrum, but is absent in LiFePO4, which could allow the easy formation of energy filtered images. The intensity of this peak, non sensitive to the precise orientation of the crystal, is large enough to rapidly determine existing phases in the sample and permit future dynamical studies. Solid solution and two-phases regions are also differentiated using Fe M2,3 / Li K edges.