Engineering topics
Kim, Sung-Kon
Publications and source records attributed to Kim, Sung-Kon.
Flexible and Wearable Fiber Microsupercapacitors Based on Carbon Nanotube–Agarose Gel Composite Electrodes
Not provided.
High-Performance Mesostructured Organic Hybrid Pseudocapacitor Electrodes
The electrodes of a hybrid electrochemical capacitor which utilize the quinone (Q)-hydroquinone (QH 2 ) couple, a prototypical organic redox system known to provide fast and reversible proton-coupled electron-transfer reactions, are deterministically mesostructured via a colloidal templating strategy to provide good ion and electron transport pathways, enabling a high rate performance. Specifically, a conducting polymer, polypyrrole (PPy), is functionalized with a pseudocapacitive material, a Q/QH 2 -containing catechol derivative, by noncovalent interactions. The mesostructure of this hybrid material is formed into an ordered 3D porous structure by a polystyrene colloidal crystal template-assisted electrosynthesis. The catechol derivative is sufficiently bound to the PPy through noncovalent interactions to provide a volumetric capacitance as high as ≈130 F cm –3 and a capacitance retention of ≈75% over 10 000 charging/discharging cycles. Furthermore, when compared with a randomly structured electrode, the deterministically structured electrode exhibits an improved rate performance due to the mesostructure facilitated electron and ion transport.
Self-Assembly of Monodisperse Starburst Carbon Spheres into Hierarchically Organized Nanostructured Supercapacitor Electrodes
We report a three-dimensional (3D) porous carbon electrode containing both nanoscale and microscale porosity, which has been hierarchically organized to provide efficient ion and electron transport. The electrode organization is provided via the colloidal self-assembly of monodisperse starburst carbon spheres (MSCSs). The periodic close-packing of the MSCSs provides continuous pores inside the 3D structure that facilitate ion and electron transport (electrode electrical conductivity ~0.35 S m –1 ), and the internal meso- and micropores of the MSCS provide a good specific capacitance. Here, the capacitance of the 3D-ordered porous MSCS electrode is ~58 F g –1 at 0.58 A g –1 , 48% larger than that of disordered MSCS electrode at the same rate. At 1 A g –1 the capacitance of the ordered electrode is 57 F g –1 (95% of the 0.24 A g –1 value), which is 64% greater than the capacitance of the disordered electrode at the same rate. The ordered electrode preserves 95% of its initial capacitance after 4000 charging/discharging cycles.
Selective Wetting-Induced Micro-Electrode Patterning for Flexible Micro-Supercapacitors
Selective wetting-induced micro-electrode patterning is used to fabricate flexible micro-supercapacitors (mSCs). Here, the resulting mSCs exhibit high performance, mechanical stability, stable cycle life, and hold great promise for facile integration into flexible devices requiring on-chip energy storage.
Facile fabrication of graphene composite microwires via drying-induced size reduction of hydrogel filaments
Graphene based electrical conductors are under consideration for numerous applications in energy storage, energy conversion devices, electronics and sensors. Here, we report a facile and versatile method for fabrication of graphene based composite microwires ranging from ~20 to 250 μm in diameter via size reduction during dehydration of extruded larger diameter graphene oxide-loaded agarose hydrogel fibers. The graphene oxide is effectively reduced to graphene by chemical and thermal treatment. Here, after dehydration and reduction, the resulting graphene composite microwires exhibit high electrical conductivities of up to 1.8 S m –1 .
Superior Pseudocapacitive Behavior of Confined Lignin Nanocrystals for Renewable Energy-Storage Materials
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