Fast-Charging, Long-Running, Bendable Supercapacitor

University College London, United Kingdom

A new bendable supercapacitor made from graphene has been developed that charges quickly and safely stores a record-high level of energy for use over a long period. The technology overcomes the issue faced by high-powered, fast-charging supercapacitors: they usually cannot hold a large amount of energy in a small space.

The bendable supercapacitor. (Photo: University College of London)

The new supercapacitor is extremely promising for next-generation energy storage technology as either a replacement for current battery technology, or for use alongside it, to provide the user with more power. It was designed with materials that give it a high power density and a high energy density. It also can bend to 180 degrees without affecting performance and doesn’t use a liquid electrolyte, which minimizes risk of explosion and makes it suitable for integrating into phones or wearable electronics.

A graphene electrode material with pores can be changed in size to store the charge more efficiently. This tuning maximizes the energy density of the supercapacitor to 88.1 Wh/L (Watt-hour per liter). Similar fast-charging commercial technology has a relatively poor energy density of 5-8 Wh/L and traditional slowcharging; long-running lead-acid batteries used in electric vehicles typically have 50-90 Wh/L. Power density is two orders of magnitude higher at over 10,000 Watt per liter.

Even when bent at 180 degrees, the supercapacitor performed almost the same as when it was flat and after 5,000 cycles, it retained 97.8 percent of its capacity. (Photo: University College of London)

The researchers made electrodes from multiple layers of graphene, creating a dense but porous material capable of trapping charged ions of different sizes. They characterized it using a range of techniques and found it performed best when the pore sizes matched the diameter of the ions in the electrolyte. The optimized material, which forms a thin film, was used to build a proof-of-concept device with both high power and high energy density.

The 6 × 6-cm supercapacitor was made from two identical electrodes layered on either side of a gel-like substance that acted as a chemical medium for the transfer of electrical charge. This was used to power dozens of light-emitting diodes (LEDs) and was found to be highly robust, flexible, and stable.

For more information, contact Bex Caygill at This email address is being protected from spambots. You need JavaScript enabled to view it.; +44 (0)20 3108 3846.