Researchers collaborating between Nanyang Technological University (NTU), Singapore, Tsinghua University (TUC), China, and Case Western Reserve University (CWRU), US, believe they have developed the highest-capacity carbon-based supercapacitor to date, and it’s thin enough to use as thread.
Because capacitors can be cycled thousands of times without degrading, supercapacitors could be the next step in practically everything that runs on batteries, from watches and medical devices to smart buildings and hybrid and electric vehicles. Even current lithium-ion [Li-Ion] battery technology can only be cycled about 800 times before its capacity begins to degrade. While researchers work hard to develop longer-lasting Li-ion battery and cycling technology, very little has come along in recent years.
The problem with capacitors, however, is their need for a huge surface area in order to function, which limits their application. Supercapacitor development, especially with the ever-expanding knowledge of graphene, has been growing steadily, however. Nanomaterials, such as graphene nanotubes, have exponentially greater surface area, on a molecular level, than macromaterials.
The multi-university-developed supercapacitor uses acid-oxidized single-wall carbon nanotubes and graphene oxide, along with a nitrogen doping agent, ethylenediamine. The mixture self-assembles, producing a flexible superconductor thread. The surface area of the thread is an astonishing 396 m2/g (square meters per gram), which increases the energy density to a record 6.3 µWh/g (micro-Watt-hours per gram). They’ve also cycled the supercapacitor thread over 10,000 times with just a 7% drop in capacity.
Currently, researchers have been able to synthesize up to 50 m of the new hybrid supercapacitor, but believe that unlimited lengths could be possible. Because the supercapacitor thread could be woven into cloth, researchers believe it could have a myriad uses, such as powering medical devices or wearable electronics. The flexible nature of the supercapacitor means it could possibly be molded into any shape, for endless possible applications.