title: Colloidal nanocrystals of lithiated group 14 elements.
abstract: The synthesis of colloidal nanocrystals (NCs) of lithiated group 14 elements (Z=Si, Ge, and Sn) is reported, which are Li4.4 Si, Li3.75 Si, Li4.4 Ge, and Li4.4 Sn. Lix Z compounds are highly reactive and cannot be synthesized by existing methods. The success relied on separating the surface protection from the crystal formation and using a unique passivating ligand. Bare Lix Z crystals were first produced by milling elemental Li and Z in an argon-filled jar. Then, under the assistance of additional milling, hexyllithium was added to passivate the freshly generated Lix Z NCs. This ball-milling-assisted surface protection method may be generalized to similar systems, such as Nax Z and Kx Z. Moreover, Li4.4 Si and Li4.4 Ge NCs were conformally encapsulated in carbon fibers, providing great opportunities for studying the potential of using Lix Z to mitigate the volume-fluctuation-induced poor cyclability problem confronted by Z anodes in lithium-ion batteries.
authors.affiliation: Department of Chemistry and Geochemistry, Colorado School of Mines, 1012 14th Street, Golden, CO 80401 (USA) http://inside.mines.edu/∼yonyang/Home.html.
authors.forename: Jacqueline E
authors.initials: JE
authors.lastname: Cloud
authors.forename: Yonglong
authors.initials: Y
authors.lastname: Wang
authors.forename: Tara S
authors.initials: TS
authors.lastname: Yoder
authors.forename: Lauren W
authors.initials: LW
authors.lastname: Taylor
authors.forename: Yongan
authors.initials: Y
authors.lastname: Yang
keywords: anode materials; colloids; group 14 elements; nanoparticles; prelithiation