Engineering topics
Kang, Seok Ju
Publications and source records attributed to Kang, Seok Ju.
Reactive boride infusion stabilizes Ni-rich cathodes for lithium-ion batteries
Engineered polycrystalline electrodes are critical to the cycling stability and safety of lithium-ion batteries, yet it is challenging to construct high-quality coatings at both the primary- and secondary-particle levels. Here, we present a room-temperature synthesis route to achieve full surface coverage of secondary particles and facile infusion into grain boundaries, thus offering a complete “coating-plus-infusion” strategy. Cobalt boride metallic glass is successfully applied to Ni-rich layered cathode LiNi 0.8 Co 0.1 Mn 0.1 O 2 . Here, it dramatically improves the rate capability and cycling stability, including under high-discharge-rate and elevated-temperature conditions and in pouch full cells. The superior performance originates from simultaneous suppression of microstructural degradation of intergranular cracking and side reactions with electrolyte. Atomistic simulations identified the critical role of strong selective interfacial bonding, which offers not only a large chemical driving force to ensure uniform reactive wetting and facile infusion but also lowered the surface/interface oxygen activity, contributing to the exceptional mechanical and electrochemical stabilities of the infused electrode.
Unveiling Nickel Chemistry in Stabilizing High-Voltage Cobalt-Rich Cathodes for Lithium-Ion Batteries
We present a practical solution to increase the stability of 4.45 V LiCoO 2 via high-temperature Ni doping, without adding any extra synthesis step or cost. We identify how a putative uniform bulk doping with highly soluble elements can profoundly modify the surface chemistry and structural stability from systematic chemistry and microstructure analysis. This modification has an electronic origin, where surface-oxygen-loss induced Co reduction that favors tetrahedral site and causes damaging spinel phase formation is replaced by Ni reduction that favors octahedral site and creates a better cation-mixed structure. Furthermore, our findings point to many unknown surface effects on the electrochemical performance of battery electrode materials hidden behind extensively practiced bulk doping strategy. The new understanding of complex surface chemistry is expected to help develop higher-energy-density cathode materials for battery applications.
Solid-state materials formed of molecular clusters and method of forming same
A solid-state material comprising a solid-state compound is provided. The solid-state compound has the formula: [Cluster1][Cluster2]n, where Cluster1 can be a metal chalcogenide molecular cluster, Cluster2 a carbon cluster, and n the number of Cluster2 clusters in the solid-state compound. A method of forming a solid-state material is also provided.
Epitaxially Self-Assembled Alkane Layers for Graphene Electronics
The epitaxially grown alkane layers on graphene are prepared by a simple drop-casting method and greatly reduce the environmentally driven doping and charge impurities in graphene. Here, multiscale simulation studies exhibit that this enhancement of charge homogeneity in graphene originates from the lifting of graphene from the SiO 2 surface toward the well-ordered and rigid alkane self-assembled layers.
A Supramolecular Complex in Small-Molecule Solar Cells Based on Contorted Aromatic Molecules
Abstract Not Provided
Organic Field Effect Transistors Based on Graphene and Hexagonal Boron Nitride Heterostructures
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Controlled Doping in Thin-Film Transistors of Large Contorted Aromatic Compounds
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Ligand chemistry of titania precursor affects transient photovoltaic behavior in inverted organic solar cells
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Using self-organization to control morphology in molecular photovoltaics
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Supersized contorted aromatics
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