High rate delithiation behaviour of LiFePO4 studied by quick X-ray absorption spectroscopy

Yu, Xiqian; Wang, Qi; Zhou, Yong‐Ning; Li, Hong; Yang, Xiao‐Qing; Nam, Kyung‐Wan; Ehrlich, Steven N.; Khalid, Syed; Meng, Ying Shirley

doi:10.1039/c2cc36382h

Cited by 55 publications

(43 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As the spectra of Fe K edge shown in Fig. 1, with Fe oxidation from LiFePO 4 to FePO 4 in the delithiation process, a clear shift occurs at the absorption edge, which is consistent with previous literature 32,33 . After collecting the XANES data at each electrochemical stage, while fitting with the linear combination of the two reference spectra, chemical phase information at each pixel can be obtained.…”

Section: Resultssupporting

confidence: 79%

In operando tracking phase transformation evolution of lithium iron phosphate with hard X-ray microscopy

2014

View full text Add to dashboard Cite

The delithiation reaction in lithium ion batteries is often accompanied by an electrochemically driven phase transformation process. Tracking the phase transformation process at nanoscale resolution during battery operation provides invaluable information for tailoring the kinetic barrier to optimize the physical and electrochemical properties of battery materials. Here, using hard X-ray microscopy-which offers nanoscale resolution and deep penetration of the material, and takes advantage of the elemental and chemical sensitivity-we develop an in operando approach to track the dynamic phase transformation process in olivine-type lithium iron phosphate at two size scales: a multiple-particle scale to reveal a rate-dependent intercalation pathway through the entire electrode and a single-particle scale to disclose the intraparticle two-phase coexistence mechanism. These findings uncover the underlying twophase mechanism on the intraparticle scale and the inhomogeneous charge distribution on the multiple-particle scale. This in operando approach opens up unique opportunities for advancing high-performance energy materials.

show abstract

Section: Resultssupporting

confidence: 79%

In operando tracking phase transformation evolution of lithium iron phosphate with hard X-ray microscopy

2014

View full text Add to dashboard Cite

show abstract

“…[1][2][3] When incident X-ray photons with energy greater than the binding energy are absorbed by an atom, a corelevel electron is removed from its quantum level. In XAS, the absorption coefficient, μ(E) is measured as a function of X-ray energy E. Detailed descriptions of X-ray absorption theory and equation have been included in many excellent books and review papers.…”

Section: Introductionmentioning

confidence: 99%

Automated generation and ensemble-learned matching of X-ray absorption spectra

et al. 2018

View full text Add to dashboard Cite

X-ray absorption spectroscopy (XAS) is a widely used materials characterization technique to determine oxidation states, coordination environment, and other local atomic structure information. Analysis of XAS relies on comparison of measured spectra to reliable reference spectra. However, existing databases of XAS spectra are highly limited both in terms of the number of reference spectra available as well as the breadth of chemistry coverage. In this work, we report the development of XASdb, a large database of computed reference XAS, and an Ensemble-Learned Spectra IdEntification (ELSIE) algorithm for the matching of spectra. XASdb currently hosts more than 800,000 K-edge X-ray absorption near-edge spectra (XANES) for over 40,000 materials from the open-science Materials Project database. We discuss a high-throughput automation framework for FEFF calculations, built on robust, rigorously benchmarked parameters. FEFF is a computer program uses a real-space Green's function approach to calculate X-ray absorption spectra. We will demonstrate that the ELSIE algorithm, which combines 33 weak "learners" comprising a set of preprocessing steps and a similarity metric, can achieve up to 84.2% accuracy in identifying the correct oxidation state and coordination environment of a test set of 19 K-edge XANES spectra encompassing a diverse range of chemistries and crystal structures. The XASdb with the ELSIE algorithm has been integrated into a web application in the Materials Project, providing an important new public resource for the analysis of XAS to all materials researchers. Finally, the ELSIE algorithm itself has been made available as part of veidt, an open source machine-learning library for materials science.npj Computational Materials (2018) 4:12 ; doi:10.1038/s41524-018-0067-x INTRODUCTION X-ray absorption spectroscopy (XAS) is a widely used technique in the study of the properties, physical states, and local environments of materials.1-3 When incident X-ray photons with energy greater than the binding energy are absorbed by an atom, a corelevel electron is removed from its quantum level. In XAS, the absorption coefficient, μ(E) is measured as a function of X-ray energy E. Detailed descriptions of X-ray absorption theory and equation have been included in many excellent books and review papers.

show abstract

“…The structure and valence changes are usually evaluated by X-ray diffraction (XRD) [15][16][17][18] and X-ray absorption near edge structure (XANES) [19][20][21] techniques, respectively. In the pioneering works with the XRD and XANES techniques, 22,23 each measurement was carried out separately.…”

mentioning

confidence: 99%

Research Update: Retardation and acceleration of phase separation evaluated from observation of imbalance between structure and valence in LiFePO4/FePO4 electrode

et al. 2014

View full text Add to dashboard Cite

LiFePO4 is a potential positive electrode material for lithium ion batteries. We have experimentally observed an imbalance between the valence change of Fe ions and the structure change from the LiFePO4 phase to the FePO4 phase during delithiation by simultaneous in situ XRD and XANES measurements in an LiFePO4/FePO4 electrode. The ratio of structure change to valence change clearly indicates that the phase separation from LiFePO4 to FePO4 is suppressed at the beginning of delithiation, while it is accelerated at the latter stage, which is due to the coherent strain caused by the lattice misfit between the two phases.

show abstract

High rate delithiation behaviour of LiFePO4 studied by quick X-ray absorption spectroscopy

Cited by 55 publications

References 31 publications

In operando tracking phase transformation evolution of lithium iron phosphate with hard X-ray microscopy

In operando tracking phase transformation evolution of lithium iron phosphate with hard X-ray microscopy

Automated generation and ensemble-learned matching of X-ray absorption spectra

Research Update: Retardation and acceleration of phase separation evaluated from observation of imbalance between structure and valence in LiFePO4/FePO4 electrode

Contact Info

Product

Resources

About