8 research outputs found

    Structure-Selective Operando X‑ray Spectroscopy

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    The relationship between charge transport and structural transformations dictates the properties of electrochemical systems. Despite their importance, the reduction–oxidation (redox) reactions within dynamically coexisting structures have so far eluded direct operando investigation. Here, we use resonant X-ray scattering to select X-ray spectra of a crystal structure coexisting with a different structure during a redox-induced phase transformation in P2-Na2/3Ni1/3Mn2/3O2. The spectra of the P2 structure become static midway through the sodium extraction in an operando coin cell, while the overall desodiation proceeds. The coincident emergence of the O2 structure reveals the rigid link between the local redox and the long-range order in this archetypal sodium-ion battery material. Structure-selective X-ray spectroscopy thus opens a powerful avenue for resolving the dynamic chemistry of different structural phases in multistructure electrochemical systems

    Data_Sheet_1_Diversity of electroencephalographic patterns during propofol-induced burst suppression.docx

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    Burst suppression is a brain state consisting of high-amplitude electrical activity alternating with periods of quieter suppression that can be brought about by disease or by certain anesthetics. Although burst suppression has been studied for decades, few studies have investigated the diverse manifestations of this state within and between human subjects. As part of a clinical trial examining the antidepressant effects of propofol, we gathered burst suppression electroencephalographic (EEG) data from 114 propofol infusions across 21 human subjects with treatment-resistant depression. This data was examined with the objective of describing and quantifying electrical signal diversity. We observed three types of EEG burst activity: canonical broadband bursts (as frequently described in the literature), spindles (narrow-band oscillations reminiscent of sleep spindles), and a new feature that we call low-frequency bursts (LFBs), which are brief deflections of mainly sub-3-Hz power. These three features were distinct in both the time and frequency domains and their occurrence differed significantly across subjects, with some subjects showing many LFBs or spindles and others showing very few. Spectral-power makeup of each feature was also significantly different across subjects. In a subset of nine participants with high-density EEG recordings, we noted that each feature had a unique spatial pattern of amplitude and polarity when measured across the scalp. Finally, we observed that the Bispectral Index Monitor, a commonly used clinical EEG monitor, does not account for the diversity of EEG features when processing the burst suppression state. Overall, this study describes and quantifies variation in the burst suppression EEG state across subjects and repeated infusions of propofol. These findings have implications for the understanding of brain activity under anesthesia and for individualized dosing of anesthetic drugs.</p

    Elucidating the Limit of Li Insertion into the Spinel Li<sub>4</sub>Ti<sub>5</sub>O<sub>12</sub>

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    In this work, we show that the well-known lithium-ion anode material, Li4Ti5O12, exhibits exceptionally high initial capacity of 310 mAh g–1 when it is discharged to 0.01 V. It maintains a reversible capacity of 230 mAh g–1, far exceeding the “theoretical” capacity of 175 mAh g–1 when this anode is lithiated to the composition Li7Ti5O12. Neutron diffraction analyses identify that additional Li reversibly enters into the Li7Ti5O12 to form Li8Ti5O12. density functional theory (DFT) calculations reveal the average potentials of the Li4Ti5O12 to Li7Ti5O12 step and the Li7Ti5O12 to Li8Ti5O12 step are 1.57 and 0.19 V, respectively, which are in excellent agreement with experimental results. Transmission electron microscopy (TEM) studies confirm that the irreversible capacity of Li4Ti5O12 during its first cycle originates from the formation of a solid electrolyte interface (SEI) layer. This work clarifies the fundamental lithiation mechanism of the Li4Ti5O12, when lithiated to 0.01 V vs Li

    Elucidating the Limit of Li Insertion into the Spinel Li<sub>4</sub>Ti<sub>5</sub>O<sub>12</sub>

    No full text
    In this work, we show that the well-known lithium-ion anode material, Li4Ti5O12, exhibits exceptionally high initial capacity of 310 mAh g–1 when it is discharged to 0.01 V. It maintains a reversible capacity of 230 mAh g–1, far exceeding the “theoretical” capacity of 175 mAh g–1 when this anode is lithiated to the composition Li7Ti5O12. Neutron diffraction analyses identify that additional Li reversibly enters into the Li7Ti5O12 to form Li8Ti5O12. density functional theory (DFT) calculations reveal the average potentials of the Li4Ti5O12 to Li7Ti5O12 step and the Li7Ti5O12 to Li8Ti5O12 step are 1.57 and 0.19 V, respectively, which are in excellent agreement with experimental results. Transmission electron microscopy (TEM) studies confirm that the irreversible capacity of Li4Ti5O12 during its first cycle originates from the formation of a solid electrolyte interface (SEI) layer. This work clarifies the fundamental lithiation mechanism of the Li4Ti5O12, when lithiated to 0.01 V vs Li

    Elucidating the Limit of Li Insertion into the Spinel Li<sub>4</sub>Ti<sub>5</sub>O<sub>12</sub>

    No full text
    In this work, we show that the well-known lithium-ion anode material, Li4Ti5O12, exhibits exceptionally high initial capacity of 310 mAh g–1 when it is discharged to 0.01 V. It maintains a reversible capacity of 230 mAh g–1, far exceeding the “theoretical” capacity of 175 mAh g–1 when this anode is lithiated to the composition Li7Ti5O12. Neutron diffraction analyses identify that additional Li reversibly enters into the Li7Ti5O12 to form Li8Ti5O12. density functional theory (DFT) calculations reveal the average potentials of the Li4Ti5O12 to Li7Ti5O12 step and the Li7Ti5O12 to Li8Ti5O12 step are 1.57 and 0.19 V, respectively, which are in excellent agreement with experimental results. Transmission electron microscopy (TEM) studies confirm that the irreversible capacity of Li4Ti5O12 during its first cycle originates from the formation of a solid electrolyte interface (SEI) layer. This work clarifies the fundamental lithiation mechanism of the Li4Ti5O12, when lithiated to 0.01 V vs Li

    Elucidating the Limit of Li Insertion into the Spinel Li<sub>4</sub>Ti<sub>5</sub>O<sub>12</sub>

    No full text
    In this work, we show that the well-known lithium-ion anode material, Li4Ti5O12, exhibits exceptionally high initial capacity of 310 mAh g–1 when it is discharged to 0.01 V. It maintains a reversible capacity of 230 mAh g–1, far exceeding the “theoretical” capacity of 175 mAh g–1 when this anode is lithiated to the composition Li7Ti5O12. Neutron diffraction analyses identify that additional Li reversibly enters into the Li7Ti5O12 to form Li8Ti5O12. density functional theory (DFT) calculations reveal the average potentials of the Li4Ti5O12 to Li7Ti5O12 step and the Li7Ti5O12 to Li8Ti5O12 step are 1.57 and 0.19 V, respectively, which are in excellent agreement with experimental results. Transmission electron microscopy (TEM) studies confirm that the irreversible capacity of Li4Ti5O12 during its first cycle originates from the formation of a solid electrolyte interface (SEI) layer. This work clarifies the fundamental lithiation mechanism of the Li4Ti5O12, when lithiated to 0.01 V vs Li
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