title: Graphene Folding in Si Rich Carbon Nanofibers for Highly Stable, High Capacity Li-Ion Battery Anodes.
abstract: Silicon nanoparticles (Si NPs) wrapped by graphene in carbon nanofibers were obtained via electrospinning and subsequent thermal treatment. In this study, water-soluble poly(vinyl alcohol) (PVA) with low carbon yield is selected to make the process water-based and to achieve a high silicon yield in the composite. It was also found that increasing the amount of graphene helps keep the PVA fiber morphology after carbonization, while forming a graphene network. The fiber SEM and HRTEM images reveal that micrometer graphene is heavily folded into sub-micron scale fibers during electrospinning, while Si NPs are incorporated into the folds with nanospace in between. When applied to lithium-ion battery anodes, the Si/graphene/carbon nanofiber composites show a high reversible capacity of ∼2300 mAh g(-1) at a charging rate of 100 mA/g and a stable capacity of 1191 mAh g(-1) at 1 A/g after more than 200 cycles. The interconnected graphene network not only ensures the excellent conductivity but also serves as a buffering matrix for the mechanic stress caused by volume change; the nanospace between Si NPs and folded graphene provides the space needed for volume expansion.
authors: School of Chemical and Biomolecular Engineering, Cornell University , Ithaca, New York 14853, United States.
authors: Ling
authors: L
authors: Fei
authors: School of Chemical and Biomolecular Engineering, Cornell University , Ithaca, New York 14853, United States.
authors: Brian P
authors: BP
authors: Williams
authors: School of Chemical and Biomolecular Engineering, Cornell University , Ithaca, New York 14853, United States.
authors: Sang H
authors: SH
authors: Yoo
authors: School of Chemical and Biomolecular Engineering, Cornell University , Ithaca, New York 14853, United States.
authors: Jangwoo
authors: J
authors: Kim
authors: School of Chemical and Biomolecular Engineering, Cornell University , Ithaca, New York 14853, United States.
authors: Ghazal
authors: G
authors: Shoorideh
authors: School of Chemical and Biomolecular Engineering, Cornell University , Ithaca, New York 14853, United States.
authors: Yong Lak
authors: YL
authors: Joo
keywords: Li-ion batteries; electrospinning; graphene; nanofibers; silicon