The demand for energy continues to rise, and researchers work continually to make batteries and capacitors more efficient.
Recently, a new energy storage device – a supercapacitor – was made. A supercapacitor is an electrochemical battery in which more energy is stored and could be used in cold temperatures. A successful supercapacitor requires a large accessible surface area for transporting and storing energy.
A group of scientists from Nanyang Technological University (NTU) in Singapore, Tsinghua University in China, and Case Western Reserve University in the United States, has developed a supercapacitor that is capable of storing the highest volumetric energy density – 6.3 microwatt hours per cubic millimetre.
According to one of the scientists, Liming Dai, “most supercapacitors have high power density but low energy density, which means they can charge quickly and give a boost of power, but don’t last long. Conversely, batteries have high energy density and low power density, which means they can last a long time, but don’t deliver a large amount of energy quickly.”
To address this issue, the team used hybrid fiber-structured materials. A mixture of acid-oxidized single-wall nanotubes, graphene oxide and ethylenediamine, is placed inside a capillary column and heated for six hours. It is firmly packed inside the capillary column allowing a higher volumetric energy density. The sheets of grapheme are then aligned and assembled in an organized porous network. This arrangement gives ample surface area needed for the transport and storage of charges.
During testing stage, the supercapacitor proved very efficient. According to another scientist from the group, Dingshan Yu, “We have tested the fiber device for 10,000 charge/discharge cycles, and the device retains about 93 percent of its original performance, while conventional rechargeable batteries have a lifetime of less than 1000 cycles.”
This new fibrous storage device is very flexible and could be woven into clothing. According to Yuan Chen, a professor of chemical engineering at Tsinghua University, “because they remain flexible and structurally consistent over their length, the fibers can also be woven into a crossing pattern into clothing for wearable devices in smart textiles.” It could be used in wearable medical devices, communication equipment for soldiers and other small electronics.
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