Capacitors play a major role in the production of portable electronics, computing systems and electric vehicles, but there is room for improvement.
While batteries provide high storage capacity, but a slow delivery of energy, capacitors provide fast delivery, but poor storage capacity.
Researchers have spent a lot of time trying to find a solution to this issue, called energy density, and now, researchers from the University of Delaware (UD) and the Chinese Academy of Sciences may have just stumbled upon the answer using nanotechnology.
"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.
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. As far as the team knows, this is the first time that 3-D nanoscale interdigital electrodes have been attained in practice.
"With their high surface area relative to their size, carbon nanotubes embedded in uniquely designed and structured 3-D architectures have enabled us to address the low ability of dielectric capacitors to store energy,” says Wei.
One of the keys to the success of the new capacitor is an interdigitated design like interwoven fingers between two hands with "gloves”, which dramatically decreases the distance between opposing electrodes and therefore increases the ability of the capacitor to store an electrical charge.
Another unique feature that the capacitors possessed, that made it all possible, is the new 3-D nanoscale electrode, which offers high voltage breakdown, meaning that the integrated dielectric material (alumina, Al2O3) does not easily fail in its intended function as an insulator.
"In contrast to previous versions, we expect our newly structured dielectric capacitors to be more suitable for field applications that require high energy density storage, such as accessory power supply and hybrid power systems," adds Wei.
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