Quantitative analysis of Li distributions in battery material Li1-xFePO4 using Fe M2,3-edge and valence electron energy loss spectra

Shunsuke Kobayashi; Craig A J Fisher; Akihide Kuwabara; Yoshio Ukyo; Yuichi Ikuhara

doi:10.1093/jmicro/dfx012

Quantitative analysis of Li distributions in battery material Li1-xFePO4 using Fe M2,3-edge and valence electron energy loss spectra

Microscopy (Oxf). 2017 Aug 1;66(4):254-260. doi: 10.1093/jmicro/dfx012.

Authors

Shunsuke Kobayashi¹, Craig A J Fisher¹, Akihide Kuwabara¹, Yoshio Ukyo², Yuichi Ikuhara^{1

3}

Affiliations

¹ Nanostructures Research Laboratory, Japan Fine Ceramics Center, Atsuta, Nagoya 456-8587, Japan.
² Office of Society-Academia Collaboration for Innovation, Kyoto University, Uji, Kyoto 611-0011, Japan.
³ Institute of Engineering Innovation, The University of Tokyo, Bunkyo, Tokyo 113-8656, Japan.

PMID: 28431172
DOI: 10.1093/jmicro/dfx012

Abstract

The spatial distribution of Li ions in a lithium iron phosphate (Li1-xFePO4) single crystal after chemical delithiation is quantitatively investigated using Fe M2,3-edge and valence electron energy loss (EEL) spectroscopy techniques. Li contents between those of end-member compositions LiFePO4 and FePO4 are found to correspond to reproducible changes in Fe M2,3-edge and valence EEL spectra across an interface between LiFePO4 and FePO4 regions. Quantitative analysis of these changes is used to estimate the local valence states of Fe ions, from which the Li concentration in the intermediate phase can be deduced. The faster recording time for valence EEL spectra than Fe M2,3-edge spectra makes measurement of the former a more efficient and reproducible means of estimating Li distributions.

Keywords: EEL spectroscopy; delithiation; lithium iron phosphate; valence EELS.