(1) Increased energy storage capacity (capacitance) twentyfold while also including energy harvesting characteristics by constructing a carbon nanotube corrugated structure that retains electrical/mechanical performance despite extreme stretchability. (2) Created fiber electrodes with improved mechanical drive and energy storage capacities by activating even the inside of porous carbon nanotube fibers.

"Published in outstanding academic journals in the field such as ‘Composite parts B: Engineering (IF=11.322, top 1.630% in JCR)’ and ‘ACS Applied Materials & Interfaces (IF=10.383, top 14.058% in JCR)"

Professor Choi Chang-soon's research team created corrugated microstructure carbon nanotube composite fibers with up to 600% elasticity for use in conductors, supercapacitors, and energy harvesters.

A research team led by Master Yoo Seong-joon (first author) and Professor Choi Chang-soon (corresponding author) from Dongguk University created a multi-functional fiber electrode by loading a carbon nanotube sheet onto polymer fibers to form micro-sized wrinkles on the surface. The carbon nanotube corrugated microstructure created in this way has high elasticity (600%) and conductivity, as well as the ability to form micro-sized pores from the contact surface of the polymer core, allowing for approximately 20 times higher capacitance compared to a plain structure without micro-wrinkles and mechano-electrochemistry-based energy production. The polymer/carbon nanotube corrugated microstructure, which can achieve several performance capabilities in a single structure, can be employed in various fields, including biosensors, energy harvesters, and energy storage devices.

'This study is significant in that it demonstrated structural stability, mechanical elasticity, energy storage performance improvement, and energy harvesting in a single structure through the fabrication of the corrugated microstructure of carbon nanotubes,' said Professor Choi Chang-soon.

Meanwhile, this research team recently completed another study on fiber-type carbon nanotube electrodes in collaboration with Hanyang University. By electrochemically activating up to the inside of the car's porous structure, a research team led by Professor Choi Chang-soon of Dongguk University's Department of Energy and Materials Engineering (corresponding author) and Professor Kim Seon-jeong of Hanyang University's Department of Electronic Engineering (co-corresponding author) succeeded in developing a carbon nanotube fiber electrode with dramatically improved mechanical drive and energy storage performance. Carbon nanotube fiber electrodes are promising electrode candidates with a wide range of applications because they have excellent mechanical and electrical properties as well as a unique structure that provides a highly effective reaction area due to the dense concentration of millions of nano-bundles aligned in a single direction and nano-micro channels between bundles. However, because of the stability of the carbon-to-carbon network, which does not react well with other materials, there were numerous practical restrictions.

The existing technology is an oxygen plasma procedure that uses plasma to functionalize the carbon network exposed on the surface, and it proved unable to activate fiber electrodes with internal structures several tens of micrometers in size. The research team applied electrochemical voltage to tackle this challenge. The nano-micro channel's electrostatic pull and capillary action allow the reactant to penetrate and activate the carbon nanotube fiber electrode down to the deep region of the fiber. The produced fiber electrode demonstrated excellent water reactivity, high hydrophilicity with a contact angle of approximately 38°, excellent rotational driving performance in a humid environment (986 revolutions/m), and a capacitance approximately 25 times more than before treatment (72.8 mF/cm2).

According to Professor Changsoon Choi, "This study is remarkable since it activated carbon nanotube fibers as a whole using a new technique known as electrochemical processing. It will be employed as a base electrode in various industries in the future, including soft robots, fabric batteries, and water/wet harvesting, and will represent a technical tipping point that will drastically improve device performance." Researcher Sohn Won-gyeong (co-first author) and Lee Jae-myeong (co-first author) participated in this research.

<From left, Professor Choi Chang-soon, Master Yoo Seong-joon, Researcher Sohn Won-gyeong, Researcher Lee Jae-myeong of the Department of Energy and Materials Engineering>

The research results were published in the March 2023 issue of 「Composites part B: Engineering (IF=11.322)」, a renowned international journal in the field of engineering, and 「ACS Applied Materials & Interfaces (IF=10.383)」, a journal in the field of nanoscience and technology.