Kookheon Char 교수

The unparalleled theoretical specific energy of lithium-sulfur (Li-S) batteries has attracted considerable research interest from within the battery community. However, most of the long cycling results attained thus far relies on using a large amount of electrolyte in the cell, which adversely affects the specific energy of Li-S batteries. This shortcoming originates from the low solubility of polysulfides in the electrolyte. Here, 1,3-dimethyl-2-imidazolidinone (DMI) is reported as a new high d

Highly efficient dye-sensitized solar cells (DSSCs) with excellent long-term stability were fabricated based on tin(IV) oxide (SnO2) nanocrystals with tunable morphologies and band energy levels. The nanocrystals were prepared by a facile, fast, and energy-saving microwave-assisted solvothermal reaction. Through variation of the precursor base used during nanocrystal synthesis control over morphology was achieved—precursor metal cations are known to have a strong influence on the growth process

Abstract Polysulfide dissolution into the electrolyte and poor electric conductivity of elemental sulfur are well‐known origins for capacity fading in lithium–sulfur batteries. Various smart electrode designs have lately been introduced to avoid these fading mechanisms, most of which demonstrate significantly improved cycle life. Nevertheless, an in‐depth understanding on the effect of sulfur microstructure and nanoscale electron transport near sulfur is currently lacking. In this study, the aut

Lithium–sulfur (Li–S) batteries continue to be considered promising post‐lithium‐ion batteries owing to their high theoretical energy density. In pursuit of a Li–S cell with long‐term cyclability, most studies thus far have relied on using ether‐based electrolytes. However, their limited ability to dissolve polysulfides requires a high electrolyte‐to‐sulfur ratio, which impairs the achievable specific energy. Recently, the battery community found high donor electrolytes to be a potential solutio

ABSTRACT The synthesis of high content sulfur copolymers via the inverse vulcanization of elemental sulfur and 1,3‐diisopropenylbenzene (DIB) on a one‐kilogram scale is reported in a single step process. Investigation into the effects of temperature, reaction scale, and comonomer feed ratios on the inverse vulcanization process of S 8 and DIB were explored to suppress the Trommsdorf effect and enable large scale synthesis of these copolymers. The copolymers were then successfully used as the act

ABSTRACT Recent developments in the use of polymeric materials as device components in lithium sulfur (Li‐S) batteries are reviewed. Li‐S batteries have generated tremendous interest as a next generation battery exhibiting charge capacities and energy densities that greatly exceed Li‐ion battery technologies. In this Highlight, the first comprehensive review focusing on the use of polymeric materials throughout these devices is provided. The key role polymers play in Li‐S technology is presented

Measurements have been made on the effects of a thin layer of polystyrene-poly(methyl methacrylate) diblock copolymer on the toughness of the interface between poly(methyl methacrylate) and poly(phenylene oxide). For a wide range of copolymer molecular weights, provided the interface is not saturated with copolymer, the interfacial toughness is a function of just the areal density ∑ of the copolymer molecules, independent of their molecular weight. The toughness was found to vary with ∑2 in acco

Polyaniline/montmorillonite (MMT) nanocomposites containing different PANI contents were prepared by the intercalation of aniline monomer into pristine MMT followed by the subsequent oxidative polymerization of the aniline in the interlayer spacings. The polyaniline/MMT nanocomposite structure intercalated with polyaniline (PANI) was examined by X-ray diffraction (XRD) and transmission electron microscopy (TEM). From the full-width at half-maximum (FWHM) of the (001) reflection peaks in the XRD

Recent studies of all-solid-state batteries (ASSBs) have identified sulfide-based electrolytes with comparable ionic conductivities as those of liquid counterparts. Nevertheless, solution-based manufacturing is unestablished, since it is challenging to find adhesive polymeric binders that can be dispersed in common solvents with sulfide electrolytes. Currently available binders exhibit insufficient electrode adhesion due to their low polarity and are compromised by the chemical stability of a sl

We report on the fabrication of wholly polymeric one-dimensional (1-D) photonic crystals (i.e., Bragg reflectors, Bragg mirrors) via solution processing for use in the near (NIR) and the short wave (SWIR) infrared spectrum (1-2 μm) with very high reflectance (<i>R</i> ∼ 90-97%). Facile fabrication of these highly reflective films was enabled by direct access to solution processable, ultrahigh refractive index polymers, termed, Chalcogenide Hybrid Inorganic/Organic Polymers (CHIPs). The high refr