There are really only two choices for energy storage: batteries, which store a lot of electricity in toxic chemicals, and capacitors, which store far less electricity than batteries, but do so between harmless metal plates. But now, a new type of ultracapacitor utilizes computer chip production techniques to provide almost as much electricity as batteries, but with safety and longevity of a capacitor.
Developed by materials scientists at Drexel University in Philadelphia, the ultracapacitor consists of a Greek key design etched into a carbon film. Each bend of the key serves as a capacitor panel, enabling vast numbers of capacitors to be printed onto thin films. Thanks to the high volume and low size enabled by the etching process, these carbon film ultracapacitors can store three-times as much energy as conventional ultracapacitors (but still far less energy than a battery).
However, even though this ultracapacitor doesn't store as much electricity as a battery, it stores enough to serve as the energy source in a number of important technologies. For one, these capacitors could be printed directly onto the back of solar cells, replacing heavier and more toxic batteries in portable, solar powered electronics. Also, since the ultracapacitor resides on a thin carbon sheet, it forms the ideal power source for printed and flexible electronics.
With battery technology advancing as well, it is unlikely that capacitors will ever overtake batteries as the primary electricity storage medium for most devices. But as this development demonstrates, ultracapacitors may become the energy source of choice for the small, flexible, low-energy devices increasingly present in so many products.