Expects to Commercialize Wearable High-Performance Battery with the Development of Super-coiled Fibers

DGIST Senior Researcher Changsoon Choi’s team coiled the existing carbon nano tube/spandex fiber and developed a new fiber of supercoiled structure. Expects to be applied in developing various wearable device platforms with super-coil that stretches up to 16 times

a Schematic illustration of highly twisted spandex @carbon nanotube (CNT) fibre, consisting of first-coils and supercoils. Inset shows a schematic of microscale buckled surface. Scanning electron microscopy (SEM) images for b microscopic scaled buckles formed on the surface of spandex@CNT fibre relaxed from pre-strain (scale bar = 15 μm), and c its magnification showing uniaxially aligned CNT bundles (scale bar = 5 μm). SEM images for d noncoiled, e first coiled, and f supercoiled spandex@CNT fibres, showing subsequent structure transformations as the number of twists increases (scale bars for d, e, and f are 200 μm). Inset images from e and f show fibre transformations from noncoiled fibre into first coil, and from first coil into supercoil, respectively. The arrows indicate the propagation direction of coil formation

DGIST announced on Monday, February 18 that Senior Researcher Changsoon Choi’s team in Smart Textile Research Group developed super-elastic multifunctional super-coiled fibers that stretch up to 16 times maximum and maintain electronic characteristics at the same time.

The research and development of 1D conductor using fiber has recently drawn great interest because it can
be widely used in various electronic fields such as wearable, biosensor, and transplantable microelectronic devices. Senior Researcher Changsoon Choi’s team was inspired by a DNA structure and sought to develop a fiber imitating this. Thus, they coiled spandex fiber surrounded by carbon nano tube and realized super-coil structure. While the newly developed fiber stretches by 16 times in length, it does not have any decline in electrical conductivity.

The new highly-twisted supercoils for super-elastic multi-functional fibers are made by coiling fibers, unlike the existing spandex fiber. The coiled fiber can stretch longer than its original length like telephone wire, so it is expected to be applied in various industrial fields including signal transmission cable that needs super-elasticity as well as robot arms and exoskeleton, and electronic circuits that require high flexibility. Also, the team showed a possibility of developing a new storage battery using super-coiled fibers. Senior Researcher Changsoon Choi’s team succeeded in the experiment of developing a high-elastic wearable supercapacitor* that can expand the energy storage volume by 11 times while having high capacitance** value using super-coiled fibers, taking a step further towards the commercialization of wearable high-performance battery.

Senior Researcher Changsoon Choi in the DGIST Smart Textile Research Group said “Through this research, we’ve acquired super-elastic fiber electrode and minimized the decrease of electronic characteristics which was the limitation of existing technology. By conducting a further research for adding other functions to the super-coiled fibers developed this time, we will strive to make sure that super-coiled fibers can be a more effective and universal material in the wearable device field in the near future.”

The research result was published on the online version of ‘Nature Communications,’ the sister magazine of Nature which is one of the world’s most-renowned academic journal on January 25, and was also selected as a featured article in the Energy Materials field.

Meanwhile, this research was led by Senior Researcher Changsoon Choi and Researcher Wonkyung Son, with Director Sangkyu Lim in the Smart Textile Research Group, Principal Researcher Sunmun Jeong, Researcher Jaemyung Lee, and Senior Researcher Younghoon Kim at Solar Energy Research Center in DGIST, as well as through a joint research with Sungkyunkwan University, Hanyang University, and Osong Medical Innovation Foundation.

* Super-capacitor: Especially strengthened the performance of electricity in capacitor (condenser) to be used as a battery part.
** Capacity: Accumulates charge when potentials are given between insulated conductors