Scientists have taken a large step toward making a fiber-like energy storage device that can be woven into clothing and power wearable medical monitors, communications equipment or other small electronics.
The device is a supercapacitor—a cousin to the battery. This one packs an interconnected network of grapheneGraphene is an allotrope of carbon, whose structure is one-atom-thick planar sheets of sp2-bonded carbon atoms that are densely packed in a honeycomb crystal lattice. and carbon nanotubes so tightly that it stores energy comparable to some thin-film lithium batteries—an area where batteries have traditionally held a large advantage.
The product’s developers, engineers and scientists at Nanyang Technological University (NTU) in Singapore, Tsinghua University in China, and Case Western Reserve University in the United States, believe the storage capacity by volume (called volumetric energy densityA figure of merit usually expressed in Joules per cubic inch for capacitorsA figure of merit usually expressed in Joules per cubic inch for capacitorsA figure of merit usually expressed in Joules per cubic inch for capacitors) is the highest reported for carbon-based microscale supercapacitorsUnconventional internal design yields a larger capacitanceThat property of a system of conductors and dielectrics which permits the storage of electricity when potential difference exists between the conductors. Its value is expressed as the ratio of a quantity of electricity to a potential difference. A capacitance value is always positive. per unit volume than other types. Valuable for high-current and low frequencyThe number of complete cycles or vibrations per unit of time. Rate of alternation in an AC current. Expressed in cycles per second or hertz (Hz). electrical circuits, power supply filters, etc. Applications are similar to those of rechargeable batteries. to date: 6.3 microwatt hours per cubic millimeter.
The device also maintains the advantage of charging and releasing energy much faster than a battery. The fiber-structured hybrid materials offer huge accessible surface areas and are highly conductive.
The researchers have developed a way to continuously produce the flexible fiber, enabling them to scale up production for a variety of uses. To date, they’veVolumetric Efficiency made 50-meter long fibers, and see no limits on length.
They envision the fiber supercapacitor could be woven into clothing to power medical devices for people at home, or communications devices for soldiers in the field. Or, they say, the fiber could be a space-saving power source and serve as “energy-carrying wires” in medical implants.