University of Glasgow researchers engineered a flexible supercapacitor made of layers of graphene and polyurethane that can obtain solar energy and store excess energy for future use. Their study was published in the journal Advanced Science.
Professor Ravinder Dahiya and his team showcased how the new material works by supplying power to different devices. Some of these include a string of 85 LEDs and a prosthetic hand that has high-torque motors. The material was able to provide power to grasp different objects.
The University of Glasgow's Bendable Electronics and Sensing Technologies (BEST) research team produced its latest innovation in autonomous electronic skin and wearables.
The BEST group of researchers developed a graphene top layer sensitive to touch. Graphene is an allotrope of carbon that is just one atom thick.
Power is generated through solar energy that passes through the top layer of the graphene via a layer of flexible photovoltaic cells below. The supercapacitor made of graphite and polyurethane stores excess power.
Power-generating chemical reactions take place in a special graphite to polyurethane ratio that offers a large, electroactive surface area. This results in a fast charging and discharging energy-dense flexible supercapacitor.
Typical single supercapacitors can only deliver voltages equal to or less than one volt. With 2.5 volts as the new capacitor's capacity, this newly-developed device can power many electronic devices.
Quality assurance tests showed that the supercapacitor can store the power it generates for 15,000 times with no significant loss.
Lead researcher Professor Ravinder Dahiya said: "This is the latest development in a string of successes we've had in creating flexible, graphene-based devices which are capable of powering themselves from sunlight.
"Our previous generation of flexible e-skin needed around 20 nanowatts per square centimeter for its operation, which is so low that we were getting surplus energy even with the lowest-quality photovoltaic cells on the market.
"We were keen to see what we could do to capture that extra energy and store it for use at a later time, but we weren't satisfied with current types of energy storages devices such as batteries to do the job, as they are often heavy, non-flexible, prone to getting hot, and slow to charge.
"Our new flexible supercapacitor, which is made from inexpensive materials, takes us some distance towards our ultimate goal of creating entirely self-sufficient flexible, solar-powered devices which can store the power they generate.
"There's huge potential for devices such as prosthetics, wearable health monitors, and electric vehicles which incorporate this technology, and we're keen to continue refining and improving the breakthroughs we've made already in this field."