Reactivity of lithium exposed graphite surface

Harilal, S. S.; Allain, Jean Paul; Hassanein, A.; Hendricks, Matthew R.; Nieto-Pérez, M.

doi:10.1016/j.apsusc.2009.06.009

Cited by 39 publications

(16 citation statements)

References 33 publications

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“…Both of these features are in agreement with reported values for Li 2 O. 49,50 Along with these changes in electrode E, there is a relative decrease in the intensity of the P 2p and V 2p features, as well as a slight decrease in the C 1s signal from the carbon black. This is ascribed to the formation of the Li 2 O at the cathode surface, i.e.…”

Section: ■ Results and Discussionsupporting

confidence: 91%

Interfacial Effects in ε-Li_xVOPO₄ and Evolution of the Electronic Structure

et al. 2015

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The epsilon polymorph of vanadyl phosphate ε-VOPO 4 is a promising cathode material for high-capacity Li ion batteries, owing to its demonstrated ability to reversibly incorporate two lithium ions per redox center. As lithium is inserted into the nanosized particles within the cathode, the electrochemical reaction can be largely affected by the interfacial chemistry at the nanoparticle surface. We performed X-ray photoelectron spectroscopy using both soft (XPS) and hard (HAXPES) X-rays to chemically distinguish and depth-resolve the interfacial phase transitions in ε-VOPO 4 electrodes as a function of electrochemical discharge. Our analysis shows that the second lithium reaction begins before the full incorporation of the first lithium. This results in a pronounced lithium gradient within the nanoparticles, with the ε-Li 2 VOPO 4 phase only forming near the surface. These results indicate that a disruption of the kinetics are limiting the realized capacity in our hydrothermally synthesized ε-VOPO 4. Moreover, from inspection of the valence band region, we were able to monitor the evolution of ε-VOPO 4 to ε-Li 2 VOPO 4 at the surface of our nanoparticles. These assignments are confirmed by hybrid density functional theory of the three end phases.

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Section: ■ Results and Discussionsupporting

confidence: 91%

Interfacial Effects in ε-Li_xVOPO₄ and Evolution of the Electronic Structure

et al. 2015

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“…Figure 4 shows the peak evolution during Ar sputter cleaning of a NSTX tile sample. The as-received spectra were similar to those reported by Harilal, et al 42 The deuterium related chemistry was revealed in the Dual peaks were observed in the O1s and Li1s energy regions. As sputter cleaning progressed, the relative intensity of the dual O1s and Li1s peaks changed.…”

Section: B Nstx Tile Analysissupporting

confidence: 76%

Differentiating the role of lithium and oxygen in retaining deuterium on lithiated graphite plasma-facing components

et al. 2014

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Laboratory experiments have been used to investigate the fundamental interactions responsible for deuterium retention in lithiated graphite. Oxygen was found to be present and play a key role in experiments that simulated NSTX lithium conditioning, where the atomic surface concentration can increase to >40% when deuterium retention chemistry is observed. Quantum-classical molecular dynamic simulations elucidated this oxygendeuterium effect and showed that oxygen retains significantly more deuterium than lithium in a simulated matrix with 20% lithium, 20% oxygen, and 60% carbon.Simulations further show that deuterium retention is even higher when lithium is removed from the matrix. Experiments artificially increased the oxygen content in graphite to ~16% and then bombarded with deuterium. XPS showed depletion of the oxygen and no enhanced deuterium retention, thus demonstrating that lithium is essential in retaining the oxygen that thereby retains deuterium.

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“…24 The areas under the peaks are weighted using the relative intensities of the spectral lines. 25,26 For the optical emission studies, we employed a 0.5 m spectrograph equipped with an intensified charge-coupled device ͑ICCD͒ to characterize the plasma parameters. The spectrograph was equipped with three gratings of 1800 grooves/mm, 600 grooves/mm, and 150 grooves/mm with effective dispersions of 13.1 nm/mm, 3.1 nm/mm, and 0.74 nm/mm respectively.…”

Section: Experimental Set Upmentioning

confidence: 99%

The effect of laser wavelength on emission and particle dynamics of Sn plasma

Campos

Harilal

Hassanein

2010

Journal of Applied Physics

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We investigated the effects of laser wavelength on the atomic, ionic, and radiative emission from laser-produced tin plasmas. For generating plasmas, planar tin targets were excited using either high intensity neodymium-doped yttrium aluminum garnet ͑Nd:YAG, 1.06 m͒ or carbon dioxide ͑CO 2 , 10.6 m͒ laser pulses; both are considered to be potential excitation lasers for an extreme ultraviolet ͑EUV͒ lithography laser-produced plasma light source. Various diagnostic tools were utilized for investigating ionic, neutral, and radiative emission from Sn plasmas including Faraday cup, witness plate in conjunction with x-ray photoelectron spectroscopy ͑XPS͒, EUV, and visible emission spectroscopy and photography. Atomic and ionic analysis showed that the amount of debris emitted by the Nd:YAG generated plasmas was considerably higher than the CO 2 laser-produced plasmas. The angular distributions of both atomic and ionic debris were found to be more forward-centric for the 1.06 m generated plasma while being much more uniform for the 10.6 m heated plasma. EUV and visible emission images of the plasma also showed a forward-centric appearance for 1.06 m heated plasmas. The strength of excited neutral emission was considerably lower for the case of the 10.6 m plasma while the kinetic energies of ions debris were found to be much higher for CO 2 generated plasmas. Surface analysis of the craters created by the lasers showed that the mass ablation rate is 3.6 times higher for Nd:YAG laser generated plasmas compared to CO 2 generated plasmas at maximum EUV emission.

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Reactivity of lithium exposed graphite surface

Cited by 39 publications

References 33 publications

Interfacial Effects in ε-Li_xVOPO₄ and Evolution of the Electronic Structure

Interfacial Effects in ε-Li_xVOPO₄ and Evolution of the Electronic Structure

Differentiating the role of lithium and oxygen in retaining deuterium on lithiated graphite plasma-facing components

The effect of laser wavelength on emission and particle dynamics of Sn plasma

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Reactivity of lithium exposed graphite surface

Cited by 39 publications

References 33 publications

Interfacial Effects in ε-LixVOPO4 and Evolution of the Electronic Structure

Interfacial Effects in ε-LixVOPO4 and Evolution of the Electronic Structure

Differentiating the role of lithium and oxygen in retaining deuterium on lithiated graphite plasma-facing components

The effect of laser wavelength on emission and particle dynamics of Sn plasma

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Product

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Interfacial Effects in ε-Li_xVOPO₄ and Evolution of the Electronic Structure

Interfacial Effects in ε-Li_xVOPO₄ and Evolution of the Electronic Structure