Capacitors are 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 energy density of dielectric capacitors, which comprise an insulating material sandwiched between two conducting metal plates.
Researchers at the University of Delaware and the Chinese Academy of Sciences have achieved an energy density of about two watt-hours per kilogram, which is significantly higher than that of other dielectric capacitor structures. One of the keys 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.