Lithium

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Samir Kumar Lahiri - One of the best experts on this subject based on the ideXlab platform.

  • Design of Single Mode Annealed Proton Exchanged LiNbO^3 Waveguides by Effective-Index Based Matrix Method
    Journal of Optics, 2006
    Co-Authors: Pranabendu Ganguly, Juran Chandra Biswas, Samir Kumar Lahiri
    Abstract:

    Effective-index based matrix method is used to analyse annealed proton exchanged (APE) LiNbO_3 waveguides. The variation of refractive index with the fabrication parameters, such as, exchange time, annealing time, waveguide width, and transmitting wavelength is studies. The computed surface refractive index changes of the waveguides are compared with the published experimental results. The 2D transverse refractive index profile of the APE Lithium niobate waveguide is transformed to the laterial 1D effective index profile by WKB method, which is then disc reused using a partitioning scheme. The matrix method is then applied to obtain the propagation constants of the guided modes. Variation of propagation constant with the fabrication parameters of APE waveguide is studied and the single mode APE lithim niobate channel waveguides are designed.

  • Design of Single Mode Annealed Proton Exchanged LiNbO^3 Waveguides by Effective-Index Based Matrix Method
    Journal of Optics, 2006
    Co-Authors: Pranabendu Ganguly, Juran Chandra Biswas, Samir Kumar Lahiri
    Abstract:

    Effective-index based matrix method is used to analyse annealed proton exchanged (APE) LiNbO_3 waveguides. The variation of refractive index with the fabrication parameters, such as, exchange time, annealing time, waveguide width, and transmitting wavelength is studies. The computed surface refractive index changes of the waveguides are compared with the published experimental results. The 2D transverse refractive index profile of the APE Lithium niobate waveguide is transformed to the laterial 1D effective index profile by WKB method, which is then disc reused using a partitioning scheme. The matrix method is then applied to obtain the propagation constants of the guided modes. Variation of propagation constant with the fabrication parameters of APE waveguide is studied and the single mode APE lithim niobate channel waveguides are designed.

Yi Cui - One of the best experts on this subject based on the ideXlab platform.

  • Lithium metal stripping beneath the solid electrolyte interphase
    Proceedings of the National Academy of Sciences of the United States of America, 2018
    Co-Authors: Feifei Shi, Yi Cui, Allen Pei, David T Boyle, Jin Xie, Xiaokun Zhang
    Abstract:

    Lithium stripping is a crucial process coupled with Lithium deposition during the cycling of Li metal batteries. Lithium deposition has been widely studied, whereas stripping as a subsurface process has rarely been investigated. Here we reveal the fundamental mechanism of stripping on Lithium by visualizing the interface between stripped Lithium and the solid electrolyte interphase (SEI). We observed nanovoids formed between Lithium and the SEI layer after stripping, which are attributed to the accumulation of Lithium metal vacancies. High-rate dissolution of Lithium causes vigorous growth and subsequent aggregation of voids, followed by the collapse of the SEI layer, i.e., pitting. We systematically measured the Lithium polarization behavior during stripping and find that the Lithium cation diffusion through the SEI layer is the rate-determining step. Nonuniform sites on typical Lithium surfaces, such as grain boundaries and slip lines, greatly accelerated the local dissolution of Lithium. The deeper understanding of this buried interface stripping process provides beneficial clues for future Lithium anode and electrolyte design.

  • The synergetic effect of Lithium polysulfide and Lithium nitrate to prevent Lithium dendrite growth
    Nature Communications, 2015
    Co-Authors: Hongbin Yao, Kai Yan, Guangyuan Zheng, Zheng Liang, Yet-ming Chiang, Yi Cui
    Abstract:

    Lithium metal has shown great promise as an anode material for high-energy storage systems, owing to its high theoretical specific capacity and low negative electrochemical potential. Unfortunately, uncontrolled dendritic and mossy Lithium growth, as well as electrolyte decomposition inherent in Lithium metal-based batteries, cause safety issues and low Coulombic efficiency. Here we demonstrate that the growth of Lithium dendrites can be suppressed by exploiting the reaction between Lithium and Lithium polysulfide, which has long been considered as a critical flaw in Lithiumsulfur batteries. We show that a stable and uniform solid electrolyte interphase layer is formed due to a synergetic effect of both Lithium polysulfide and Lithium nitrate as additives in ether-based electrolyte, preventing dendrite growth and minimizing electrolyte decomposition. Our findings allow for re-evaluation of the reactions regarding Lithium polysulfide, Lithium nitrate and Lithium metal, and provide insights into solving the problems associated with Lithium metal anodes. Lithium dendrite growth is a serious hazard in battery operations. Here, the authors show that when using Lithium polysulfide and Lithium nitrate as additives in ether-based electrolyte, a stable and uniform solid electrolyte interphase forms on the Lithium surface, which prevents dendrite growth.

  • impedance analysis of silicon nanowire Lithium ion battery anodes
    Journal of Physical Chemistry C, 2009
    Co-Authors: Riccardo Ruffo, Seung Sae Hong, Candace K Chan, Robert A Huggins, Yi Cui
    Abstract:

    The impedance behavior of silicon nanowire electrodes has been investigated to understand the electrochemical process kinetics that influences the performance when used as a high-capacity anode in a Lithium ion battery. The ac response was measured by using impedance spectroscopy in equilibrium conditions at different Lithium compositions and during several cycles of charge and discharge in a half cell vs. metallic Lithium. The impedance analysis shows the contribution of both surface resistance and solid state diffusion through the bulk of the nanowires. The surface process is dominated by a solid electrolyte layer (SEI) consisting of an inner, inorganic insoluble part and several organic compounds at the outer interface, as seen by XPS analysis. The surface resistivity, which seems to be correlated with the Coulombic efficiency of the electrode, grows at very high Lithium contents due to an increase in the inorganic SEI thickness. We estimate the diffusion coefficient of about 2 × 10−10 cm2/s for lithiu...

Clare P Grey - One of the best experts on this subject based on the ideXlab platform.

  • noninvasive in situ nmr study of dead Lithium formation and Lithium corrosion in full cell Lithium metal batteries
    Journal of the American Chemical Society, 2020
    Co-Authors: Anna B Gunnarsdottir, Chibueze V Amanchukwu, Svetlana Menkin, Clare P Grey
    Abstract:

    Capacity retention in Lithium metal batteries needs to be improved if they are to be commercially viable, the low cycling stability and Li corrosion during storage of Lithium metal batteries being even more problematic when there is no excess Lithium in the cell. Herein, we develop in situ NMR metrology to study "anode-free" Lithium metal batteries where Lithium is plated directly onto a bare copper current collector from a LiFePO4 cathode. The methodology allows inactive or "dead Lithium" formation during plating and stripping of Lithium in a full-cell Lithium metal battery to be tracked: dead Lithium and SEI formation can be quantified by NMR and their relative rates of formation are here compared in carbonate and ether-electrolytes. Little-to-no dead Li was observed when FEC is used as an additive. The bulk magnetic susceptibility effects arising from the paramagnetic Lithium metal were used to distinguish between different surface coverages of Lithium deposits. The amount of Lithium metal was monitored during rest periods, and Lithium metal dissolution (corrosion) was observed in all electrolytes, even during the periods when the battery is not in use, i.e., when no current is flowing, demonstrating that dissolution of Lithium remains a critical issue for Lithium metal batteries. The high rate of corrosion is attributed to SEI formation on both Lithium metal and copper (and Cu+, Cu2+ reduction). Strategies to mitigate the corrosion are explored, the work demonstrating that both polymer coatings and the modification of the copper surface chemistry help to stabilize the Lithium metal surface.

  • Noninvasive In Situ NMR Study of “Dead Lithium” Formation and Lithium Corrosion in Full-Cell Lithium Metal Batteries
    Journal of the American Chemical Society, 2020
    Co-Authors: Anna B Gunnarsdottir, Chibueze V Amanchukwu, Svetlana Menkin, Clare P Grey
    Abstract:

    Capacity retention in Lithium metal batteries needs to be improved if they are to be commercially viable, the low cycling stability and Li corrosion during storage of Lithium metal batteries being even more problematic when there is no excess Lithium in the cell. Herein, we develop in situ NMR metrology to study "anode-free" Lithium metal batteries where Lithium is plated directly onto a bare copper current collector from a LiFePO4 cathode. The methodology allows inactive or "dead Lithium" formation during plating and stripping of Lithium in a full-cell Lithium metal battery to be tracked: dead Lithium and SEI formation can be quantified by NMR and their relative rates of formation are here compared in carbonate and ether-electrolytes. Little-to-no dead Li was observed when FEC is used as an additive. The bulk magnetic susceptibility effects arising from the paramagnetic Lithium metal were used to distinguish between different surface coverages of Lithium deposits. The amount of Lithium metal was monitored during rest periods, and Lithium metal dissolution (corrosion) was observed in all electrolytes, even during the periods when the battery is not in use, i.e., when no current is flowing, demonstrating that dissolution of Lithium remains a critical issue for Lithium metal batteries. The high rate of corrosion is attributed to SEI formation on both Lithium metal and copper (and Cu+, Cu2+ reduction). Strategies to mitigate the corrosion are explored, the work demonstrating that both polymer coatings and the modification of the copper surface chemistry help to stabilize the Lithium metal surface.

George Adamson - One of the best experts on this subject based on the ideXlab platform.

  • performance characteristics of Lithium vanadium phosphate as a cathode material for Lithium ion batteries
    Journal of Power Sources, 2003
    Co-Authors: M Y Saidi, Jeremy Barker, Haitao Huang, Jeffrey Swoyer, George Adamson
    Abstract:

    Abstract The properties of the monoclinic Lithium vanadium phosphate, Li3V2(PO4)3 (LVP), are investigated using X-ray diffraction (XRD) and electrochemical methods. Electrochemical measurements conducted in half cells with Li3V2(PO4)3 as the cathode material and Lithium metal as the anode have shown that this material exhibits an excellent reversibility when the charge extracted is confined to that equivalent to two Lithiums per formula unit. The extraction of the last Lithium is observed at a potential >4.6 V versus Li/Li+ and involves a significant overvoltage. Upon discharge, a solid solution behavior is observed after which the two-phase regime for the last Lithium insertion reappears. Furthermore, XRD has shown that the original structure is recovered. Cycling performance as well as rate capability are also presented for rocking-chair batteries based on LVP and graphite.

  • electrochemical properties of Lithium vanadium phosphate as a cathode material for Lithium ion batteries
    Electrochemical and Solid State Letters, 2002
    Co-Authors: M Y Saidi, Jeremy Barker, Haitao Huang, Jeffrey Swoyer, George Adamson
    Abstract:

    The properties of the monoclinic Lithium vanadium phosphate Li 3 V 2 (PO 4 ) 3 are investigated using X-ray diffraction (XRD) and electrochemical methods. Electrochemical measurements conducted in half-cells with Li 3 V 2 (PO 4 ) 3 as the cathode material and Lithium metal as the anode have shown that this material exhibits an excellent reversibility when the charge extracted is confined to that equivalent to two Lithiums per formula unit. The extraction of the last Lithium is observed at a potential greater than 4.6 V vs. Li/Li + and involves a significant overvoltage. Upon discharge, however, XRD has shown that the original structure is recovered.

Pranabendu Ganguly - One of the best experts on this subject based on the ideXlab platform.

  • Design of Single Mode Annealed Proton Exchanged LiNbO^3 Waveguides by Effective-Index Based Matrix Method
    Journal of Optics, 2006
    Co-Authors: Pranabendu Ganguly, Juran Chandra Biswas, Samir Kumar Lahiri
    Abstract:

    Effective-index based matrix method is used to analyse annealed proton exchanged (APE) LiNbO_3 waveguides. The variation of refractive index with the fabrication parameters, such as, exchange time, annealing time, waveguide width, and transmitting wavelength is studies. The computed surface refractive index changes of the waveguides are compared with the published experimental results. The 2D transverse refractive index profile of the APE Lithium niobate waveguide is transformed to the laterial 1D effective index profile by WKB method, which is then disc reused using a partitioning scheme. The matrix method is then applied to obtain the propagation constants of the guided modes. Variation of propagation constant with the fabrication parameters of APE waveguide is studied and the single mode APE lithim niobate channel waveguides are designed.

  • Design of Single Mode Annealed Proton Exchanged LiNbO^3 Waveguides by Effective-Index Based Matrix Method
    Journal of Optics, 2006
    Co-Authors: Pranabendu Ganguly, Juran Chandra Biswas, Samir Kumar Lahiri
    Abstract:

    Effective-index based matrix method is used to analyse annealed proton exchanged (APE) LiNbO_3 waveguides. The variation of refractive index with the fabrication parameters, such as, exchange time, annealing time, waveguide width, and transmitting wavelength is studies. The computed surface refractive index changes of the waveguides are compared with the published experimental results. The 2D transverse refractive index profile of the APE Lithium niobate waveguide is transformed to the laterial 1D effective index profile by WKB method, which is then disc reused using a partitioning scheme. The matrix method is then applied to obtain the propagation constants of the guided modes. Variation of propagation constant with the fabrication parameters of APE waveguide is studied and the single mode APE lithim niobate channel waveguides are designed.