A diagram of the
dielectric capacitor research.
(October 24, 2015) Nanotechnology
offers new approach to increasing storage ability of dielectric capacitors
For Back to the Future
fans, this week marked a milestone that took three decades to reach.
Oct. 21, 2015, was the day that Doc Brown and Marty McFly
landed in the future in their DeLorean, with time travel made possible by a
“flux capacitor.”
While the flux capacitor still conjures sci-fi images,
capacitors are now key components of portable electronics, computing systems,
and electric vehicles.
In contrast to batteries, which offer high storage capacity
but slow delivery of energy, capacitors provide fast delivery but poor storage
capacity.
A great deal of effort has been devoted to improving this
feature — known as energy density — of dielectric capacitors, which comprise an
insulating material sandwiched between two conducting metal plates.
Now, a group of researchers at the University of Delaware
and the Chinese Academy of Sciences has successfully used nanotechnology to
achieve this goal.
The work is reported in a paper, “Dielectric Capacitors with
Three-Dimensional Nanoscale Interdigital Electrodes for Energy Storage,”
published in Science Advances, the first open-access, online-only journal of
AAAS.
UD's Bingqing Wei
is part of a research team that has reported on the use
of nanotechnology
to improve the energy density of dielectric capacitors.
“With our approach, we achieved an energy density of about
two watts per kilogram, which is significantly higher than that of other
dielectric capacitor structures reported in the literature,” says Bingqing Wei,
professor of mechanical engineering at UD.
“To our knowledge, this is the first time that 3D nanoscale
interdigital electrodes have been realized in practice,” he adds. “With their
high surface area relative to their size, carbon nanotubes embedded in uniquely
designed and structured 3D architectures have enabled us to address the low
ability of dielectric capacitors to store energy.”
One of the keys to the success of the new capacitor is an
interdigitated design — similar to interwoven fingers between two hands with
“gloves” — that dramatically decreases the distance between opposing electrodes
and therefore increases the ability of the capacitor to store an electrical
charge.
Another significant feature of the capacitors is that the
unique new three-dimensional nanoscale electrode also offers high voltage
breakdown, which means that the integrated dielectric material (alumina, Al2O3)
does not easily fail in its intended function as an insulator.