This new kind of energy storage could be used for future flexible electronics such as solar-powered prosthetics.
The top touch sensitive layer is made from graphene, a highly flexible, transparent ‘super-material’ form of carbon layers just one atom thick. Sunlight which passes through the top layer is used to generate power via a layer of flexible photovoltaic cells below. Any surplus power is stored in a newly-developed supercapacitor, made from a graphite-polyurethane composite.
The team worked to develop a ratio of graphite to polyurethane which provides a relatively large, electroactive surface area where power-generating chemical reactions can take place, creating an energy-dense flexible supercapacitor which can be charged and discharged very quickly.
Similar supercapacitors developed previously have delivered voltages of one volt or less, making single supercapacitors largely unsuited for powering many electronic devices. The team’s new supercapacitor can deliver 2.5 volts, making it more suited for many common applications.
In laboratory tests, the supercapacitor has been powered, discharged and powered again 15,000 times with no significant loss in its ability to store the power it generates.
In a demonstration, the team powered a series of devices, including a string of 84 power-hungry LEDs and the high-torque motors in a prosthetic hand, allowing it to grasp a series of objects.