Thermodynamics, Kinetics and Structural Evolution of ε-LiVOPO<sub>4</sub> over Multiple Lithium Intercalation

Lin, Yuh-Chieh; Wen, Bohua; Wiaderek, Kamila M.; Sallis, Shawn; Liu, Hao; Lapidus, Saul H.; Borkiewicz, Olaf J.; Quackenbush, Nicholas F.; Chernova, Natasha A.; Karki, Khim; Omenya, Fredrick; Chupas, Peter J.; Piper, Louis F. J.; Whittingham, M. Stanley; Chapman, Karena W.; Ong, Shyue Ping

doi:10.1021/acs.chemmater.5b04880

Cited by 66 publications

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“…[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

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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.

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Section: Introductionmentioning

confidence: 99%

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

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“…Since this work, the approach has been advanced further to allow its combination with conventional powder diffraction. A study of the lithiation/delithiation of the LiVOPO 4 nanocomposite using the 11-ID-B beamline at the APS utilized 3 min data acquisitions alternating between PDF and X-ray powder diffraction every 15 min at 0.06 C (equivalent to 0.015 Li intervals) (Lin et al, 2016). Further operando PDF measurements on beamline 11-ID-B using this setup were performed to examine the sodiation of antimony as a negative electrode for sodium-ion batteries (Allan et al, 2016).…”

Section: Synchrotron X-ray Sources: 4-60 S Resolutionmentioning

confidence: 99%

Real-time powder diffraction studies of energy materials under non-equilibrium conditions

Peterson

Auckett

Pang

2017

Int Union Crystallogr J

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Energy materials form the central part of energy devices. An essential part of their function is the ability to reversibly host charge or energy carriers, and analysis of their phase composition and structure in real time under nonequilibrium conditions is mandatory for a full understanding of their atomicscale functional mechanism. Real-time powder diffraction is increasingly being applied for this purpose, forming a critical step in the strategic chemical engineering of materials with improved behaviour. This topical review gives examples of real-time analysis using powder diffraction of rechargeable battery electrodes and porous sorbent materials used for the separation and storage of energy-relevant gases to demonstrate advances in the insights which can be gained into their atomic-scale function.

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“…3.0 -1.5 V vs. Li + /Li), the Lithium insertion into LiVPO4F occurs at 1.8 V according to a biphasic process between LiVPO4F and Li2VPO4F involving the V III /V II redox couple29 . The Lithium insertion into LiVPO4O leads to the reduction of V IV to V III according to a complex series of phase transitions occurring at 2.48 V, 2.31 V and 2.03 V vs.Li + /Li, to reach the composition Li2V III PO4O 30,31. Figure 8b shows the galvanostatic curves of the mixed valence materials cycled in the 3.0 -1.0 V vs. Li + /Li voltage range (involving the V II /V III and V III /V IV =O redox couples) at C/10.…”

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LiVPO₄F_1–yO_y Tavorite-Type Compositions: Influence of the Concentration of Vanadyl-Type Defects on the Structure and Electrochemical Performance

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Mixed-valence LiVPO4F1–y O y materials were obtained for the first time over a large composition range (here 0.35 ≤ y ≤ 0.75) through a single-step solid-state synthesis. Interestingly, the competition between the ionic character of the V3+–F bond and the strong covalency of the V4+O vanadyl bond originates complex crystal chemistry at the local scale, which allows stabilization of a solid solution between LiVPO4F and LiVPO4O despite a significant deviation from Vegard’s law for the cell parameters. A combined study using IR, Raman, and X-ray absorption spectroscopies highlights the effect of the vanadyl environment on the electronic structure of the vanadium orbitals and a fortiori the electrochemical behavior. Our results underline that the electrochemical performance of LiVPO4F1–y O y -type materials can be controlled by tuning the concentration of vanadyl-type defects, i.e., by playing on the competition between the ionic V3+–F bond and the covalent V4+O bond.

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Thermodynamics, Kinetics and Structural Evolution of ε-LiVOPO₄ over Multiple Lithium Intercalation

Cited by 66 publications

References 65 publications

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

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

Real-time powder diffraction studies of energy materials under non-equilibrium conditions

LiVPO₄F_1–yO_y Tavorite-Type Compositions: Influence of the Concentration of Vanadyl-Type Defects on the Structure and Electrochemical Performance

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Thermodynamics, Kinetics and Structural Evolution of ε-LiVOPO4 over Multiple Lithium Intercalation

Cited by 66 publications

References 65 publications

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

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

Real-time powder diffraction studies of energy materials under non-equilibrium conditions

LiVPO4F1–yOy Tavorite-Type Compositions: Influence of the Concentration of Vanadyl-Type Defects on the Structure and Electrochemical Performance

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Thermodynamics, Kinetics and Structural Evolution of ε-LiVOPO₄ over Multiple Lithium Intercalation

LiVPO₄F_1–yO_y Tavorite-Type Compositions: Influence of the Concentration of Vanadyl-Type Defects on the Structure and Electrochemical Performance