Seung Jae Yang

Metal–Phenolic Carbon Nanocomposites for Robust and Flexible Energy-Storage Devices

Future electronics applications such as wearable electronics depend on the successful construction of energy-storage devices with superior flexibility and high electrochemical performance. However, these prerequisites are challenging to combine: External forces often cause performance degradation, whereas the trade-off between the required nanostructures for strength and electrochemical performance only results in diminished energy storage. Herein, a flexible supercapacitor based on tannic acid (TA) and carbon nanotubes (CNTs) with a unique nanostructure is presented. TA was self-assembled on the surface of the CNTs by metal-phenolic coordination bonds, which provides the hybrid film with both high strength and high pseudocapacitance. Besides 17-fold increased mechanical strength of the final composite, the hybrid film simultaneously exhibits excellent flexibility and volumetric capacitance.

Impact of large-scale meso- and macropore structures in adenosine-derived affordable noble carbon on efficient reversible oxygen electrocatalytic redox reactions

In this report, we delineate a successful synthesis of a high performance and affordable adenosine-derived noble carbon cathode for LOBs with bifunctional electrocatalytic activity and show that the pore structure of the cathode is a key feature to control the electrochemical performance of this electrochemical system.

Easy preparation of partially-opened carbon nanotubes by simple air oxidation for high performance Li–S batteries

The thermal decomposition behavior of multi-walled carbon nanotubes (MWCNTs) was revisited to prepare partially opened MWCNTs by a simple air oxidation method which allows mass-productivity. As a promising matrix for sulfur cathodes, the partially opened MWCNTs can incorporate sulfur in hidden internal areas in the carbon nanotubes, leading to a homogeneous distribution through the MWCNT matrix. The resulting materials enable Li–S batteries to exhibit greatly enhanced electrochemical performance.

Morphochemical imprinting of melamine cyanurate mesocrystals in glucose-derived carbon for high performance lithium ion batteries

A novel dual imprinting method is suggested to synthesize pyridinic N-enriched, hierarchically porous carbon. Rose-like melamine cyanurate (MCA) mesocrystals are prepared by simple self-assembly and utilized as a sacrificial template. The unique morphological and chemical features of the MCA are imprinted in the carbon source during carbonization. Curled graphene-like layers with a high nitrogen content (19.9 at%, especially 8.9 at% of pyridinic N) are interconnected to form a unique red blood cell-shaped morphology with a hierarchical pore structure. The resulting material exhibits an outstanding electrochemical performance (2019 mA h g−1 at 100 mA g−1 and 643 mA h g−1 at 2000 mA g−1 after 250 cycles) when evaluated as an anode material for lithium ion batteries. Furthermore, this novel imprinting strategy can provide a simple and efficient methodology to produce pyridinic N-enriched, hierarchically porous carbonaceous materials for extensive applications.