title: Hierarchical Graphene-Containing Carbon Nanofibers for Lithium-Ion Battery Anodes.
abstract: We present a method to produce composite anodes consisting of thermally reduced graphene oxide-containing carbon nanofibers (TRGO/CNFs) via electrospinning a dispersion of polyacrylonitrile (PAN) and graphene oxide (GO) sheets in dimethylformamide followed by heat treatment at 650 °C. A range of GO (1-20 wt % GO relative to polymer concentration) was added to the polymer solution, with each sample comprising similar polymer chain packing and subsequent CNF microstructure, as assessed by X-ray diffraction. An increase from 0 to 20 wt % GO in the fibers led to carbonized nonwovens with enhanced electronic conductivity, as TRGO sheets conductively connected the CNFs. Galvanostatic half-cell cycling revealed that TRGO addition enhanced the specific discharge capacity of the fibers. The optimal GO concentration of 5 wt % GO enhanced first-cycle discharge capacities at C/24 rates (15.6 mA g(-1)) 150% compared to CNFs, with a 400% capacity increase at 2-C rates (750 mA g(-1)). We attribute the capacity enhancement to a high degree of GO exfoliation. The TRGO/CNFs also experienced no capacity fade after 200 cycles at 2-C rates. Impedance spectroscopy of the composite anodes demonstrated that charge-transfer resistances decreased as GO content increased, implying that high GO loadings result in more electrochemically active material.
authors.affiliation: Department of Chemical and Biomolecular Engineering, North Carolina State University , 911 Partners Way, Raleigh, North Carolina 27695, United States.
authors.forename: Martin K
authors.initials: MK
authors.lastname: Dufficy
authors.affiliation: Department of Chemical and Biomolecular Engineering, North Carolina State University , 911 Partners Way, Raleigh, North Carolina 27695, United States.
authors.forename: Saad A
authors.initials: SA
authors.lastname: Khan
authors.affiliation: Department of Chemical and Biomolecular Engineering, North Carolina State University , 911 Partners Way, Raleigh, North Carolina 27695, United States.
authors.forename: Peter S
authors.initials: PS
authors.lastname: Fedkiw
keywords: anode; carbon nanofibers; electrospinning; graphene; lithium-ion battery