Supercapacitors are energy storage devices that can be recharged for virtually unlimited times, but the amount of energy they store is limited. Their working principle is not based on chemical reactions, but rather on transferring surface charges.
Yuri Gogotsi, from the Drexel University in Philadelphia, along with his team of researchers, demonstrated that it’s possible to use the technology that the chip-making industry uses to make thin-film ultracapacitors that store three times as much energy density as conventional ultracapacitor materials.
Furthermore, you won’t have to ever replace ultracapacitors, like you’d do to rechargeable batteries.
Gogotsi uses a high-vacuum technique, called “chemical vapor deposition” to create thin films of metal carbides such as titanium carbide on the surface of a silicon wafer. The films are then chlorinated to remove the titanium, leaving behind a porous film of carbon. In each place where a titanium atom was, a small pore is left behind.
“The film is like a molecular sponge, where the size of each pore is equal to the size of a single ion,” says Gogotsi. This matching means that when used as the charge-storage material in an ultracapacitor, the carbon films can accumulate a large amount of total surface charge.
The Drexel researchers complete the device by adding metal electrodes to either surface to carry current into and out of the device and adding a liquid electrolyte to carry the charges. They found that the performance of the device is best when the carbon material is about 50 micrometers thick, about the same as the width of a human hair.
Theoretically, the size of the films that are made by using Gogotsi’s method is unlimited, because they are already used by the solar industry to create huge panels. These types of supercapacitors could be used in cars, in solar cells, and various gadgets to temporarily store power.