3.Research

1. Materials & Assembly

We study synthetic approaches to prepare functional materials including ion-conductive polymers, 2-dimensional nanomaterials, and carbon nanomaterials. In particular, we extensively study the assembly of those materials into multiscale structures, which are potentially applicable in electronic, wearable, and engineering applications.

Continuous Wet-spinning for Graphene Fibers and MXene Fibers 

Wet spinning is a promising strategy for manufacturing high performance graphene fiber with a large productivity. Graphene and graphene hybrid fibers are continuously produced with meter-lone scale. Carbon, 142, 230 (2019)
Fabrication of pure MXene fiber without binder and matrix have been ramained as a challenge. We fabricated pure MXene fiber with meter-long scale and the MXene fiber was highly electrical conductiive and strong.Nature  Communications, 11, 2825 (2020)

Fabrication of Ultra-strong Fibers

Controlling the microstructures in fibers, such as crystalline structures and microvoids, is a crucial challenge for the development of mechanically strong fibers. We are developing the ultra-strong fibers by  controlling the alignment of nanoassembled structure, implyting that the inherent performance characteristics of 2D nanomaterials can be shown at the level of multidimensional structures including films and fibers. 
 ACS Nano, 15(8), 13055 (2021)

Dynamic Assembly of Colloid Nanoparticle

Assembly of colloid nanomaterials,  rheological properties of thier dispersion have to be considered. We are investigating dynamic assembly of 2D nanosheets (Graphene oxide).
Science Advances, 4, eaau2104 (2018)

2. Materials for energy applications 

Our aim is to prepare high-performance electrodes and electrolytes. Ion-conductive polymers are synthesized for solid-state batteries, and we are extensively studying the interface-engineering to improve cell performance. Various anode materials for LIB and NIB and fiber-based electrodes for supercapacitors are also designed.

Electrode Materials for Lithium Ion Battery

2D nanoscale oxides have attracted a large amount of research interest due to their unique properties. Here, a facile synthetic approach to prepare graphene‐mimicking, porous 2D Co3O4 nanofoils using graphene oxide as a sacrificial template is reported. 
Adv. Funct. Mater., 26, 7605 (2016)

Supercapacitor Electrode Materials (MXene, graphene, metal oxides)

Energy storage capabilities of transition metal oxides have expanded. The fabrication of  high-performance supercapacitor electrode demands developing synergetic architectures with a variety of materials with complement conductivity and stability.
Chemical Engineering Journal, 436, 135041 (2022)Adv. Mater. Interfaces, 5, 1801361 (2018)

Fiber-type Energy Storage System for Wearable Applications

Fiber nanomaterials can become fundamental devices that can be woven into smart textiles and miniaturized fiber-based supercapacitors (FSCs). Herein, we developed porous carbon nanotube–graphene hybrid fibers for all-solid-state symmetric FSCs.
ACS Appl. Mater. Interfaces., 11, 9011 (2019)

Electrode Materials for Sodium Ion Battery

Conventional graphites do not allow Na-ion accommodation into their interlayer space owing to the large ionic radius and low stabilizing energy of Na in graphites. Here, we suggest a promising strategy for significantly increasing Na capacity by expanding the axial slab space of graphite. 
ACS Appl. Mater. Interfaces, 12, 23781 (2020)

3. Materials for ionic applications 

We are developing the harvesting of electrical energy, signal transmission systems, and mechanically operatable devices by using the movement behavior of ions.

(1) Blue energy harvesting and water-treatment: 

We generate electrical energy by using the evaporation of water as a clean energy source. We are newly synthesizing highly porous membranes for this emerging hydro-voltaic technology. In addition, we are studying a new technology to produce clean water by combing our porous membranes and heat-generating elements.

(2) Artificial nerve system: 

Like the nerve system in human body, we are transferring the electrical and chemical signal by using our ionic cables, which are applicable in robotics and electronic devices, and wearable platform.

(3) Actuators: 

we are studying ionic actuators, which are operated under specific conditions, such as light, temperatures, and pressures.

Transmission of Ionic Signal and Power with Nanochannel-based Ionic Cables

Transporting ionic species selectively and rapidly is critical not only for operating electrochemical devices but also for life-sustaining chemical transformations in all living creatures. Our ionic cables could be used for a wide range of system operated in ionic media for the transmission of ionic signals or power. 
Science Advances, 4, eaau2104 (2018)

Generation of Blue Energy with Nanochannels

A salinity-gradient power generation system harvests clean and sustainable energy from the conversion of chemical potential between sea and river water using an ion-selective membrane. Ion selective and ion conductive nanomaterials-based nanofluidic channels are crucial for osmotic energy generation and efficiency. 
J. Mat. Chem. A, 7, 23727 (2019)

Evaportion of Water can generate Electricity

The conversion of the electrokinetic energy arising from evaporation-induced water flow through nanoporous materials has great potential for renewable energy production. We are generating electricity with a nanocapillary membrane.  Our proposed nanocapillary, thin-membrane-based water evaporation-induced energy harvester (WEEH) has great practical potential for energy generation, as well as other membrane-based technologies such as water purification. 

Chemical Engineering Journal, 430, 132759 (2022)

4. Materials for thermal management

We are studying heat-dissipating and heat-generating materials. Our research focuses on the following top priorities in the semiconductor industry: 

(1) High-performance thermal interface materials (TIM)

(2) New packing materials for underfill

(3) High heat-spreading/insulating substrates for 2.5D and 3D semiconductor packaging technologies

(4) The development of low-loss materials for 5G and 6G


Additionally, high-efficiency heating is crucial for energy-saving strategies. We are studying highly efficient heating elements for space, military, and automotive purposes. To achieve this, we are (1) developing new materials such as graphene, MXene, and polymers, and (2) designing novel structures that can operate even in extreme environments.


Electrical Power Cables with low-heat Generation 

For the applications in power transport,  the low heat generation is an appealing feature. Graphene cable can transfer the electrical power without heat generation.
Chemical Engineering Journal, 414, 128803 (2021)Carbon, 142, 230 (2019)