Articles by Shawn Sallis in JoVE
Elemental-sensitive Detection of the Chemistry in Batteries through Soft X-ray Absorption Spectroscopy and Resonant Inelastic X-ray Scattering Jinpeng Wu1,2, Shawn Sallis2,3, Ruimin Qiao2, Qinghao Li2,4, Zengqing Zhuo2,5, Kehua Dai2,6, Zixuan Guo2,7, Wanli Yang2 1Geballe Laboratory for Advanced Materials, Stanford University, 2Advanced Light Source, Lawrence Berkeley National Laboratory, 3Department of Materials Science and Engineering, Binghamton University, 4School of Physics, National Key Laboratory of Crystal Materials, Shandong University, 5School of Advanced Materials, Peking University Shenzhen Graduate School, 6School of Metallurgy, Northeastern University, 7Department of Chemical Engineering, University of California-Santa Barbara Here, we present a protocol for typical experiments of soft X-ray absorption spectroscopy (sXAS) and resonant inelastic X-ray scattering (RIXS) with applications in battery material studies.
Other articles by Shawn Sallis on PubMed
High-efficiency in Situ Resonant Inelastic X-ray Scattering (iRIXS) Endstation at the Advanced Light Source The Review of Scientific Instruments. | Pubmed ID: 28372380 An endstation with two high-efficiency soft x-ray spectrographs was developed at Beamline 8.0.1 of the Advanced Light Source, Lawrence Berkeley National Laboratory. The endstation is capable of performing soft x-ray absorption spectroscopy, emission spectroscopy, and, in particular, resonant inelastic soft x-ray scattering (RIXS). Two slit-less variable line-spacing grating spectrographs are installed at different detection geometries. The endstation covers the photon energy range from 80 to 1500 eV. For studying transition-metal oxides, the large detection energy window allows a simultaneous collection of x-ray emission spectra with energies ranging from the O K-edge to the Ni L-edge without moving any mechanical components. The record-high efficiency enables the recording of comprehensive two-dimensional RIXS maps with good statistics within a short acquisition time. By virtue of the large energy window and high throughput of the spectrographs, partial fluorescence yield and inverse partial fluorescence yield signals could be obtained for all transition metal L-edges including Mn. Moreover, the different geometries of these two spectrographs (parallel and perpendicular to the horizontal polarization of the beamline) provide contrasts in RIXS features with two different momentum transfers.
Mitigating Oxygen Loss to Improve the Cycling Performance of High Capacity Cation-disordered Cathode Materials Nature Communications. | Pubmed ID: 29042560 Recent progress in the understanding of percolation theory points to cation-disordered lithium-excess transition metal oxides as high-capacity lithium-ion cathode materials. Nevertheless, the oxygen redox processes required for these materials to deliver high capacity can trigger oxygen loss, which leads to the formation of resistive surface layers on the cathode particles. We demonstrate here that, somewhat surprisingly, fluorine can be incorporated into the bulk of disordered lithium nickel titanium molybdenum oxides using a standard solid-state method to increase the nickel content, and that this compositional modification is very effective in reducing oxygen loss, improving energy density, average voltage, and rate performance. We argue that the valence reduction on the anion site, offered by fluorine incorporation, opens up significant opportunities for the design of high-capacity cation-disordered cathode materials.The performance of lithium-excess cation-disordered oxides as cathode materials relies on the extent to which the oxygen loss during cycling is mitigated. Here, the authors show that incorporating fluorine is an effective strategy which substantially improves the cycling stability of such a material.