Amorphous nonstoichiometric Ge1−x–Cx:H compounds obtained by radiolysis-chemical vapor deposition of germane/ethyne or germane/allene systems: A bonding and microstructure investigation performed by x-ray photoelectron spectroscopy and Raman spectroscopy

Benzi, Paola; Bottizzo, Elena; Demaria, Chiara; Infante, G; Iucci, Giovanna; Polzonetti, Giovanni

doi:10.1063/1.2748710

Cited by 24 publications

(12 citation statements)

References 62 publications

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“…The Raman peak located at 298 cm À1 represents the nanocrystalline Ge transverse optical (TO) mode, while the small peak at 162 cm À1 represents amorphous germanium. 30,31 Also, the XRD pattern for Ge lm shown in Fig. S3 † proves that the Ge electrode is partly nanocrystalline and partly amorphous.…”

Section: Resultsmentioning

confidence: 91%

3D ordered macroporous germanium fabricated by electrodeposition from an ionic liquid and its lithium storage properties

et al. 2013

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Among the group IVA materials, germanium has a large theoretical specific capacity, good electrical conductivity and fast lithium ion diffusivity, making it an alternative anode material for Li ion batteries.Nanostructured electrodes now are the biggest focus to solve the volume expansion problem and to improve cycling and rate performance. Ionic liquid electrodeposition was used to obtain Ge nanoparticles at room temperature, and by combining with a "hard" template, 3D macroporous frameworks have been easily synthesized. 3D ordered macroporous Ge exhibits a reversible capacity of 1024 mA h g À1 and retains a capacity of 844 mA h g À1 after 50 cycles at a rate of 0.2 C.

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Section: Resultsmentioning

confidence: 91%

3D ordered macroporous germanium fabricated by electrodeposition from an ionic liquid and its lithium storage properties

et al. 2013

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“…Appearance of the strong Raman peak located at 298 cm À1 conrms the deposition of crystalline Ge. 27 No amorphous Ge phase is found in the composite from the Raman results.…”

Section: Resultsmentioning

confidence: 94%

Germanium–graphene composite anode for high-energy lithium batteries with long cycle life

et al. 2013

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The high-energy lithium ion battery is an ideal power source for electric vehicles and grid-scale energy storage applications. Germanium is a promising anode material for lithium ion batteries due to its high specific capacity, but still suffers from poor cyclability. Here, we report a facile preparation of a germanium-graphene nanocomposite using a low-pressure thermal evaporation approach, by which crystalline germanium particles are uniformly deposited on graphene surfaces or embedded into graphene sheets. The nanocomposite exhibits a high Coulombic efficiency of 80.4% in the first cycle and a capacity retention of 84.9% after 400 full cycles in a half cell, along with high utilization of germanium in the composite and high rate capability. These outstanding properties are attributed to the monodisperse distribution of high-quality germanium particles in a flexible graphene framework.This preparation approach can be extended to other active elements that can be easily evaporated (e.g., sulfur, phosphorus) for the preparation of graphene-based composites for lithium ion battery applications.

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“…The peak at 302 cm À1 is attributed to the optical mode of crystalline germanium, which shows a small blue-shi compared to the reported value of 298 cm À1 , 11,17,35 indicating the interaction between germanium and the carbon material.…”

mentioning

confidence: 80%

“…Combining this with the blue-shi of Ge-Ge stretching, we believe that the charge transfer has occurred between germanium and the carbon components, including both the graphene sheets and the carbon layer, 11,17,35,38 indicating that the germanium nanoparticles are not just physically connected to the graphene sheets and carbon layers, but interact with the carbon network, including both the graphene and the carbon layer, by the formation of bonds.…”

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confidence: 99%

A unique sandwich-structured C/Ge/graphene nanocomposite as an anode material for high power lithium ion batteries

Seng

Shi

et al. 2013

J. Mater. Chem. A

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(2013). A unique sandwich-structured C/Ge/graphene nanocomposite as an anode material for high power lithium ion batteries. Journal of Materials Chemistry A, 1 (45), 14115-14121. A unique sandwich-structured C/Ge/graphene nanocomposite as an anode material for high power lithium ion batteries AbstractA unique sandwich-structured C/Ge/graphene composite with germanium nanoparticles trapped between graphene sheets is prepared by a microwave-assisted solvothermal reaction followed by carbon coating and thermal reduction. The graphene sheets are found to be effective in hindering the growth and aggregation of GeO2 nanoparticles. More importantly, the graphene sheets, coupled with the carbon coating, can buffer the volume changes of germanium in electrochemical lithium reactions. The unique sandwich structure features a highly conductive network of carbon, which can improve both the conductivity and the structural stability of the electrode material, and exemplifies a promising strategy for the development of new high performance electrode materials for lithium ion batteries. A unique sandwich-structured C/Ge/graphene composite with germanium nanoparticles trapped between graphene sheets is prepared by a microwave-assisted solvothermal reaction followed by carbon coating and thermal reduction. The graphene sheets are found to be effective in hindering the growth and aggregation of GeO 2 nanoparticles. More importantly, the graphene sheets, coupled with the carbon coating, can buffer the volume changes of germanium in electrochemical lithium reactions.The unique sandwich structure features a highly conductive network of carbon, which can improve both the conductivity and the structural stability of the electrode material, and exemplifies a promising strategy for the development of new high performance electrode materials for lithium ion batteries.

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Amorphous nonstoichiometric Ge1−x–Cx:H compounds obtained by radiolysis-chemical vapor deposition of germane/ethyne or germane/allene systems: A bonding and microstructure investigation performed by x-ray photoelectron spectroscopy and Raman spectroscopy

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Cited by 24 publications

References 62 publications

3D ordered macroporous germanium fabricated by electrodeposition from an ionic liquid and its lithium storage properties

3D ordered macroporous germanium fabricated by electrodeposition from an ionic liquid and its lithium storage properties

Germanium–graphene composite anode for high-energy lithium batteries with long cycle life

A unique sandwich-structured C/Ge/graphene nanocomposite as an anode material for high power lithium ion batteries

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