Chiwon Kang

Ultrathin alumina-coated carbon nanotubes as an anode for high capacity Li-ion batteries

Alumina-coated carbon nanotubes (CNTs) were synthesized on a copper substrate and have been used as an anode in Li-ion batteries. CNTs were grown directly on the copper current collector by chemical vapor deposition and an ultrathin layer of alumina was deposited on the CNTs by atomic layer deposition, thus forming the binder-free electrode for the Li-ion battery. While CNTs, which form the core of the structure, provide excellent conductivity, structural integrity and Li-ion intercalation ability, the aluminium oxide coating provides additional stability to the electrode, with further enhancement of capacity. The anode showed very high specific capacity, good capacity retention ability and excellent rate capability. This novel anode may be considered as an advanced anode for future Li-ion batteries.

Vertically oriented MoS2 nanoflakes coated on 3D carbon nanotubes for next generation Li-ion batteries

The advent of advanced electrode materials has led to performance enhancement of traditional lithium ion batteries (LIBs). We present novel binder-free MoS2 coated three-dimensional carbon nanotubes (3D CNTs) as an anode in LIBs. Scanning transmission electron microscopy analysis shows that vertically oriented MoS2 nanoflakes are strongly bonded to CNTs, which provide a high surface area and active electrochemical sites, and enhanced ion conductivity at the interface. The electrochemical performance shows a very high areal capacity of ~1.65 mAh cm-2 with an areal density of ~0.35 mg cm-2 at 0.5 C rate and coulombic efficiency of ~99% up to 50 cycles. The unique architecture of 3D CNTs-MoS2 is indicative to be a promising anode for next generation Li-ion batteries with high capacity and long cycle life.

Engineering carbon nanomaterials for future applications: energy and bio-sensor

This paper presents our recent results on carbon nanomaterials for applications in energy storage and bio-sensor. More specifically: (i) A novel binder-free carbon nanotubes (CNTs) structure as anode in Li-ion batteries. The interfacecontrolled CNT structure, synthesized through a two-step chemical vapor deposition (CVD) and directly grown on copper current collector, showed very high specific capacity - almost three times as that of graphite, excellent rate capability. (ii) A large scale graphene film was grown on Cu foil by thermal chemical vapor deposition and transferred to various substrates including PET, glass and silicon by using hot press lamination and etching process. The graphene/PET film shows high quality, flexible transparent conductive structure with unique electrical-mechanical properties; ~88.80 % light transmittance and ~ 100 Ω/sq sheet resistance. We demonstrate application of graphene/PET film as flexible and transparent electrode for field emission displays. (iii) Application of individual carbon nanotube as nanoelectrode for high sensitivity electrochemical sensor and device miniaturization. An individual CNT is split into a pair of nanoelectrodes with a gap between them. Single molecular-level detection of DNA hybridization was studied. Hybridization of the probe with its complementary strand results in an appreciable change in the electrical output signal.