Showing 187 results for Author: Jong K. Keum
Apr, 2015
Journal
In this work we have determined the room temperature electrochemical reactivity of SnO2 thin films and mesoporous carbons filled with SnO2 anodes with Na, and compare the results with those obtained during the reaction with Li. We show that SnO2 can reversibly deliver up to 6.2 Li/SnO2 whereas the reaction with Na is significantly limited. The initial discharge capacity is…
Mar, 2015
Journal
When water molecules are confined to nanoscale spacings, such as in the nanometer size pores of activated carbon fiber (ACF), their freezing point gets suppressed down to very low temperatures (∼ 150 K), leading to a metastable liquid state with remarkable physical properties. We have inves- tigated the ambient pressure diffusive dynamics of water in microporous KynolTMACF…
Jan, 2015
Journal
In this work we report the first experimental in situ determination of the thickness and estimated composition of a condensed electrode/electrolyte interface at various states of charge for the high voltage Li-ion cathode LiMn1.5Ni0.5O4 by exploiting the power of neutron reflectometry.1 Understanding the electrode/electrolyte interface is critical to developing an understa…
Oct, 2014
Journal
The electrochemical reaction of Sb and SnSb anode materials with Na results in the formation of amorphous materials. To understand the resulting phases and electrochemical capacities we studied the reaction products local order using 119Sn and 121Sb Mössbauer spectroscopies in conjunction with measurements performed on model powder compounds of Na-Sn and Na-Sb to further c…
Sep, 2014
Journal
Adding a small amount of a processing additive to the casting solution of organic blends has been demonstrated to be an effective method for achieving improved power conversion efficiency (PCE) in organic photovoltaics (OPVs). However, an understanding of the nano-structural evolution occurring in the transformation from casting solution to thin photoactive films is still…
Feb, 2014
Journal
A hybrid superionic conductor was fabricated utilizing the space charge effect between the LLZO and LPS interfaces. This space-charge effect resulted in an improvement over the individual bulk conductivities of the two systems. Sample with higher weight fractions of LLZO are limited by the porosity and grain boundary resistance arising from non-sintered membranes. By combi…
Feb, 2014
Journal
We synthesized mesoporous carbon from pre-cross-linked lignin gel impregnated with a surfactant as the pore-forming agent, and then activated the carbon through physical and chemical methods to obtain activated mesoporous carbon. The activated mesoporous carbons exhibited 1.5- to 6-fold increases in porosity with a maximum BET specific surface area of 1148 m2/g and a pore…
Jan, 2014
Journal
The attractive optoelectronic properties of conducting polymers depend sensitively upon intra- and inter-polymer chain interactions, and therefore new methods to manipulate these interactions are continually being pursued. Here, we report a study of the isotopic effects of deuterium substitution on the structure, morphology, and optoelectronic properties of regioregular po…