Hybrid Low Resistance Ultracapacitor Electrodes Based on 1-Pyrenebutyric Acid Functionalized Centimeter-Scale Graphene Sheets

Abstract

Ultracapacitors are promising candidates for alternative energy storage applications since they can store and deliver energy at relatively high rates. Here, we present hybrid nanocarbon ultracapacitor electrodes with a low equivalent series resistance (ESR) of 7 ohms. 1-pyrenebutyric acid treated large-area single layer graphene (SLG) sheets covered with shortened multi-walled carbon nanotubes (MWNTs) have been utilized as highly conductive and percolated networks of hybrid carbon nanomaterial composites or thin films as ultracapacitor electrodes. Uniform centimeter scale single layer graphene sheets were produced via low pressure chemical vapor deposition using copper foil substrates and then subsequently modified by 1-pyrenebutyric acid functionalization. Chemically shortened MWNTs ranging in length of 200-500 nm, were deposited by drop casting on 1-pyrenebutyric acid functionalized SLG films. SLG/MWNT nancomposite hybrid films of different thicknesses were obtained by controlling the density of MWNT suspension. Surface morphology and nanostructure of the hybrid nanocomposites indicated relatively dense and homogeneous web-like networks. Specific capacitance values of the hybrid electrodes were substantially increased by 200% compared to those ultracapacitors fabricated using buckypaper electrodes. Average values of specific capacitance and energy density obtained were 140.64 F/g and 21.54 Wh/kg respectively. SLG/MWNT nanocomposite electrodes are very promising for future ultracapacitor devices with their low ESR value that is 95% lower than that of buckypaper based ultracapacitors.

Building blocks for bioinspired electrets: molecular-level approach to materials for energy and electronics

“…4b), the ratios between which are concentration dependent. We ascribe the red-shifted peak, the intensity of which increases with an increase in concentration, to aggregates that form at the excited and/ or the ground state [46,[75][76][77][78][79][80]. The trends from this assignment of the fluorescence spectra indicate that the chlorinated hydrocarbons, such as DCM, tend to suppress aggregation (Fig.…”

Bioinspired molecular electrets: bottom-up approach to energy materials and applications

“…[4][5][6][7][8] Local electric fields, originating from molecular dipoles, can strongly affect the behavior of charge carriers. Molecular-scale engineering of field profiles along CT pathways provides an incomparable means for controlling the direction and the efficiency of electron and hole transduction.…”

Synthesis of Carbon Nanotube/Graphene Composites by One‐Step Chemical Vapor Deposition for Electrodes of Electrochemical Capacitors

“…Vertically aligned CNTs were directly grown by CVD (60 sccm C 2 H 2 , 120 sccm H 2 , and 200 sccm Ar, 750 ∘ C) on graphene paper coated with Fe as well as Al 2 O 3 and a higher as well as more stable discharge capacity compared with graphene paper as well as CNTs was achieved [28]. Graphene films were grown on copper foil by low pressure CVD (20 torr, 1000 ∘ C, and 100 sccm CH 4 , 200 sccm H 2 , and 200 sccm Ar), then functionalized with 1-pyrenebutyric acid by drop casting, and coated with multiwalled carbon nanotubes by drop casting after functionalization [29]. Hybrid CNTs and graphene nanostructures were directly grown by ambient pressure chemical vapor deposition (CVD); methane was introduced to form graphene on copper foils at 950 ∘ C, then Fe catalysts were deposited on graphene/copper foils by ebeam evaporation, and ethylene was next introduced to grow pillar CNTs on graphene/copper foil at 750 ∘ C [30].…”