Download Graphene Based Nanocomposite Electrodes for Energy storage in

GRAPHENE BASED NANOCOMPOSITE ELECTRODES FOR
ENERGY STORAGE IN SUPERCAPACITORS
1Ashish
Aphale*, 2Krushangi Maisuria, 3Manoj Mahapatra, 4Angela Santiago,
3Prabhakar
Singh and 5,6Prabir Patra*
1 Department of Computer Science and Engineering, University of Bridgeport, CT-06604
2 Fairfield Ludlowe High School, Fairfield, CT-06824
3 Department of Materials Science, University of Connecticut, Center for Clean Energy and
Engineering, Storrs, CT4 Department of Chemistry, University of Bridgeport, CT-06604
5 Department of Biomedical Engineering, University of Bridgeport, CT-06604
6 Department of Mechanical Engineering, University of Bridgeport, CT-06604
ABSTRACT
Global warming and depleting fossil fuels have forced us to move towards sustainable
and renewable resources for energy production. As the renewable resources of energy are not
available on demand, energy storage systems are starting to play an important role in our lives.
Currently the most popular commercialized energy storage devices are batteries, capacitors and
fuel cells. However, because of our ever increasing appetite for energy, there is a need to
improve the performances of these devices to satisfy high power requirements of various systems
ranging from portable electronics to hybrid vehicles and large industrial equipments. The gap
between the performances of devices and the power requirement can be filled by discovering
new materials for energy storage and advancing our understanding of the electrochemical
interfaces at the nanoscale level. A novel use of atomically thin carbon allotropes like graphene,
carbon nanotubes (CNTs) and electrically conducting polymers (ECPs) such as polypyrrole
(PPy) have been studied as high performance conducting electrodes in supercapacitor
application. A novel templated sustainable nanocomposite electrode has been fabricated using
cellulose extracted from Cladophora c. aegagropila algae as a component of the assembled
supercapacitor device which later has been transitioned to a unique template-less freestanding
nanocomposite supercapacitor electrode. The specific capacitance of polypyrrole-graphenecellulose nanocomposite as calculated from the cyclic voltammetry curve is 91.5 F g-1 at the scan
rate 50 mV s-1 in the presence of 1M NaCl electrolyte. The open circuit voltage of the device
with polypyrrole -graphene-cellulose electrode was found to be around 225 m V and that of the
polypyrrole -cellulose device is only 53 m V without the presence of graphene in the
nanocomposite
electrode. Understanding
the
fundamentals
by
fabricating
template
nanocomposite electrode led to developing a unique nanocomposite template-less freestanding
film which comprises of polypyrrole-graphene-CNT hybrid. Various experiments have been
performed using different electrolytes such ascorbic acid, sodium sulfate and sulfuric acid in
different scan rates. The specific capacitance of polypyrrole-graphene-CNT nanocomposite with
0.1 wt% of graphene-CNT, as calculated from cyclic voltammetry curve is 450 F g-1 at the scan
rate 5 m V s-1. For the first time a nanofibrous membrane has been developed as a separator
which acts as an electrolyte reservoir and ionic diffusion membrane. The performance of the
fabricated supercapacitor device has been analyzed using a multimeter and compared with a
conventional alkaline (1.5 V) battery. Lighting up of 2.2 V light emitting diode has been
demonstrated using the fabricated supercapacitor.