Page 314 - 00. Complete Version - Progress Report IPEN 2014-2016

314 Materials and Nanotechnology | Progress Report

Magnetic, Electric and Nu- cycling life while low energy density and low

clear Materials cell voltage are the common shortcomings.
With this perspective, supercapacitors have
been acknowledged as one of the promising
Supercapacitors – Photoelectric devices in the energy storage industry and fast
cells - Batteries progress has been made in the development

of fundamental and applied aspects of these
The increasing demand on sustainable ener- energy devices.
gy impelled the development of alternative
energy sources with high power and energy In this brief progress report, we describe our
densities. Supercapacitors, batteries and fuel recent research investigation on the prepara-
cells are typical non-conventional energy stor- tion of various nanostructured graphene and
age devices which are based on chemical to zinc oxide electrode materials and the perfor-
electrical energy conversion. These devices mances of symmetric supercapacitors. Vacu-
find extensive applications in consumer elec- um thermal reduction of graphene oxide has
tronics ranging from mobile phones, laptops, been carried out in the group of Supercapaci-
digital cameras, emergency doors and hybrid tors, Batteries and Photovoltaic cells. Graphene
vehicles etc. In all these devices, the chemical oxide nanocomposites have also been success-
energy is converted into electrical energy by fully used to prepare electrical double layer su-
means of electrochemical reactions. In fuel percapacitors. Internal series resistance has
cells, as long as the fuel is fed, the electrical been diminished with the thermal reduction
energy will be obtained and in batteries, the procedure. A post-doctorate research project
stored energy would be drawn on demand, has been carried out on this subject, which re-
requiring a recharging time afterwards. Elec- sulted in the publication of papers and a pat-
trochemical supercapacitor is a typical stor- ent deposit. A master degree on this subject
age device which possesses high specific ca- has been finalized and another patent is being
pacitance, high power density and long cycle written. A doctorate project has also been im-
life and can be used in combination with bat- plemented in the promising area of palladium
teries or fuel cells to meet the start-up at high incorporation on graphene nanomaterials and
power density. also three master degree investigation stud-
ies in carbon supercapacitors. Measurements
Electrical double layer capacitors, pseudo-ca- techniques have been applied to estimate the
pacitors and asymmetric supercapacitors are specific capacitance of the electrode nanoma-
the three types of supercapacitors, classified terials. Cyclic voltammetry and galvanostatic
on the electrochemical responses and elec- cycling have been employed with success for
trodes design. Double layer devices use high this purpose. Efforts have also been made to
surface area materials such as activated car- increase the specific capacitance of the elec-
bons or derivatives for providing high elec- trode nanomaterials. In the field of batteries,
trostatic double-layer capacitance. The sep- a doctorate has been approved and another is
aration of charge obtained in the Helmholtz being finalized. Progress has also been made
double-layer device occurs at the interface be- in the field of photovoltaic cell with the imple-
tween the conductive electrode and the electro- mentation of an automatic research facility
lyte. The advantages of these electrochemical for preparing zinc oxide nanomaterial for en-
devices include high power density and good ergy conversion devices. Zinc oxide thin films

Instituto de Pesquisas Energéticas e Nucleares