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Cabana, Kostecki – LBNL V.F.2 Novel In Situ Diagnostics Tools for Li-ion Battery Electrodes (LBNL) material because they can be packed more easily. The result would be electrodes with higher energy density. Advanced synchrotron-based techniques will enable the probing of processes occurring on increasingly shorter timescales and, through their enhanced sensitivity, to study increasingly more subtle changes. The high energy of the beam allows collection of data from whole battery ensembles. The purpose of this effort is to continue to expand our diagnostic capabilities by leveraging the two synchrotron user facilities in the Bay Area. The goal is to offer new insight into processes that determine phase transformations and the interaction of Li with its host lattice in battery materials. Approach This effort is currently centered on the use of transmission X-ray microscopy (TXM) and X-ray Raman spectroscopy (XRS). The measurements were performed at the wiggler beamline 6-2 at Stanford synchrotron radiation lightsource (SSRL). TXM is an imaging tool that provides information on the microstructure of materials. The spatial resolution is generally poorer than that for TEM, but recent advances make it possible to achieve a resolution of 20 nm, a length scale that is relevant to many battery features. TXM does not require elaborate sample preparation or exposure to high vacuum, and X-rays are less damaging to the sample than an electron beam. Both 2D and 3D images can be collected by turning the sample with respect to the beam, so that tomographic reconstructions are generated. In addition, TXM can be coupled with XAS to obtain spatially resolved chemical speciation. XRS also employs hard X-rays and provides information on the bulk electronic structure of a given element, even light ones such as Li or C, at long penetration lengths without the need of ultrahigh vacuum. XRS allows access to the same information as soft X-ray absorption spectroscopy (XAS), but uses penetrating radiation. Because these techniques do not require ultrahigh vacuum, it is possible to design a setup with liquid electrodes for in situ analysis of operating cells. Examples of proposed experiments include measurements of structural changes in carbonaceous materials upon cation and anion intercalation, and monitoring changes in species distribution within a particle in electrochemical reactions. Results 2D XANES TXM images of partially delithiated LiFePO 4 hexagonal crystals (200x2000x4000 nm) were collected at the Fe K-edge, with spatial resolution of about 25nm. The chemical resolution allows to distinguish clearly between Fe 3+ and Fe 2+ species distributed within a partially delithiated crystal. Figure V - 219a and Figure V - 219b show the single field of view images obtained below and above the edge respectively. To distinguish between species at different oxidation states, images were obtained at selected energies. For each pixel, a XANES scan was thus approximated. Figure V - 219c shows the phase map that was obtained by fitting each XANES spectra for each pixel by a linear combination of FePO 4 and LiFePO 4 . Figure V - 219: Partially delithiated LiFePO4 below (a) and above (b) the Fe K-edge and the corresponding phasemap (c) with the distribution of phases within the crystals. Some hurdles were found during these measurements. The crystals measured along the shortest dimension (200nm, i.e., lying flat) are thin enough that about 95% of the beam is transmitted above the Fe-K-edge, which leads to serious contrast issues and high signal to noise ratio. The result is an increase in the measurement time and uncertain data reliability. To circumvent this issue, even larger crystals (10x10x40 m) were analyzed. With these crystals, the method could be extended by repeating the procedure at different rotation angles along a vertical axis, leading to 3D spectroscopic imaging. The data are currently being analyzed and conclusions are expected during FY2012. During this past year, a setup to perform in operando TXM with XANES in 2D was developed. Proof of concept was shown with the conversion reaction of NiO. The selected images at different stages of the battery FY 2011 Annual Progress Report 667 Energy Storage R&D
V.F.2 Novel In Situ Diagnostics Tools for Li-ion Battery Electrodes (LBNL) Cabana, Kostecki – LBNL discharge/charge illustrate the massive changes in the collapse and the formation of nanoparticles. During the morphology that occur when Li reacts with NiO. The experiment, spectroscopic information was obtained to impact and changes of morphology are shown in Figure V - track the distribution of metallic Ni and NiO during the 220. The conversion reaction leads to a drastic volume reaction. expansion which swells the particle and leads to its Figure V - 220: Morphology changes in a NiO particle during electrochemical cycling. XRS data at the Li and C K edges was collected for a sample of highly oriented pyrolytic graphite (HOPG) before and after lithiation. The results at the C K edge (Figure V - 221) show a remarkable decrease in the * signal, which is related to the filling of unoccupied bands above the Fermi level. This filling is at the origin of the metallic character of lithiated graphite. A shift in the * signal toward lower energies was also observed, which is related to a stiffening of the C-C bonds upon lithiation. The Li K edge data show that Li is far from being completely ionized within the structure of the material, contrary to previous studies. Figure V - 221: XRS data at the C K edge for pristine and lithiated HOPG. A setup for in operando XRS was also designed and successfully tested in the laboratory. Preliminary experiments show that the setup is very well suited for the collection of XRS simultaneous to the lithiation of graphite. Results are expected during FY2012. Conclusions and Future Directions Chemical maps of the species involved in the Li deintercalation mechanism in LiFePO 4 were produced in both 2D and 3D for particles of different sizes. The distribution of phases within a crystal was uncovered. In parallel, a setup designed for in operando data collection was built and successfully used at the beamline. Further experiments will leverage this new capability to follow the chemical phase transformations front during electrochemical reactions in different battery electrodes. Attempts will be made to collect data in both 2D and 3D. Data at the Li and C K edge were collected for samples of graphite at different lithiation states. The data reveal the complex bonding nature of the material, with a covalent Li-C interaction leading to a material with metallic character. In operando measurements have also been demonstrated. Further work during FY2012 will be directed at the full leveraging of this capability to follow the chemical interactions between Li and the graphite during intercalation reactions. Energy Storage R &D 668 FY 2011 Annual Progress Report
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V. FOCUSED FUNDAMENTAL RESEARCH Int
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V.A Introduction Duong - DOE, Srini
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V.B Cathode Development V.B.1 First
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V.B.1 First Principles Calculations
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V.B.1 First Principles Calculations
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V.B.2 Cell Analysis, High-energy De
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V.B.3 Olivines and Substituted Laye
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V.B.4 Stabilized Spinels and Nano O
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V.B.4 Stabilized Spinels and Nano O
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V.B.5 The Synthesis and Characteriz
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V.B.5 Synthesis & Characterization
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V.B.6 Cell Analysis-Interfacial Pro
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V.B.6 Cell Analysis-Interfacial Pro
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V.B.7 Role of Surface Chemistry on
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V.B.8 Characterization of New Catho
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V.B.8 Characterization of New Catho
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V.B.9 Layered Cathode Materials (AN
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V.B.10 Development of High Energy C
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V.B.10 Development of High Energy C
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V.B.11 Crystal Studies on High-ener
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V.B.12 Developing Materials for Lit
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V.B.13 Studies on the Local SOC and
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V.B.13 Studies on the Local SOC and
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V.B.14 New Cathode Projects (LBNL)
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V.C.1 Nanoscale Composite Hetero-st
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V.C.1 Nanoscale Composite Hetero-st
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V.C.2 Interfacial Processes - Diagn
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V.C.3 Search for New Anode Material
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V.C.4 Nano-structured Materials as
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V.C.4 Nano-structured Materials as
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V.C.5 Development of High Capacity
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V.C.5 Development of High Capacity
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V.C.6 Advanced Binder for Electrode
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V.C.6 Advanced Binder for Electrode
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V.C.7 Three-Dimensional Anode Archi
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ARGONNE2_CDJ403T me Pro ile V.C.7 T
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V.C.8 Metal-Based High-Capacity Li-
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V.C.8 Metal-Based High-Capacity Li-
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V.C.9 New Layered Nanolaminates for
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V.C.9 New Layered Nanolaminates for
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V.C.10 Atomic Layer Deposition for
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V.C.10 Atomic Layer Deposition for
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V.C.11 Synthesis and Characterizati
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V.C.11 Polymer-Coated Layered SiOx-
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V.C.12 Synthesis and Characterizati
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V.C.12 Silicon Clathrates for Anode
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V.C.12 Silicon Clathrates for Anode
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V.C.13 Wiring Up Silicon Nanopartic
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V.C.13 Wiring Up Silicon Nanopartic
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V.C.14 Hard Carbon Materials for Hi
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V.C.14 Hard Carbon Materials for Hi
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V.D.1 Polymer Electrolytes for Adva
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V.D.1 Polymer Electrolytes for Adva
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V.D.2 Interfacial Behavior of Elect
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V.D.2 Interfacial Behavior of Elect
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V.D.3 Molecular Dynamics Simulation
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V.D.3 Molecular Dynamics Simulation
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V.D.4 Bi-functional Electrolytes fo
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V.D.4 Bi-functional Electrolytes fo
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V.D.5 Advanced Electrolyte and Elec
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V.D.6 Inexpensive, Nonfluorinated (
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V.D.6 Nonfluorinated (or Partially
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