Breakthrough research in energy storage technology could herald a new era for flexible electronic devices, including solar-powered prosthetics for amputees.
In the study, published in the Advanced Science journal, a team of engineers from the University of Glasgow explained that by using layers of graphene and polyurethane, they can create a flexible supercapacitor capable of generating power from the sun.
The team’s paper, titled ‘Graphene-Graphite Polyurethane Composites based High-Energy Density Flexible Supercapacitors‘, also showed that excess energy could be stored for later use.
Demonstrations of the new material showed a string of 84 LED lights, along with high-torque motors in a prosthetic hand being powered.
The research of energy-autonomous e-skin and wearables is the latest in a series of technological developments from the University’s Bendable Electronics and Sensing Technologies (BEST) research group, led by Professor Ravinder Dahiya.
Professor Dahiya commented: “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 centimetre 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.”
The touch-sensitive top layer developed by the research team is made from graphene, a highly flexible, transparent form of carbon layers just one atom thick.
Sunlight, which passes through this top layer, is used to generate power while surplus energy is stored in a newly-developed supercapacitor made from a graphite-polyurethane composite.
Similar supercapacitors previously developed, researchers said, have been capable of delivering voltages of one volt or less, making single supercapacitors unsuitable for powering many electronic devices.
This team’s new device can deliver 2.5 volts. In laboratory tests so far, it has been powered, discharged and powered again more than 15,000 times with no loses to its storage or power generation capabilities.
Professor Dahiya added: “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.”