The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform

Sang Young Lee - One of the best experts on this subject based on the ideXlab platform.

  • Mechanically compliant and lithium dendrite growth-suppressing composite polymer electrolytes for flexible lithium-ion batteries
    Journal of Materials Chemistry A, 2013
    Co-Authors: Se Hee Kim, Eun Hye Kil, Sung Ju Cho, Keun-ho Choi, Sang Young Lee
    Abstract:

    We demonstrate mechanically compliant and lithium dendrite growth-suppressing composite polymer electrolytes for use in flexible lithium-ion batteries. This new composite polymer electrolyte (referred to as “CPE”) is fabricated via an exquisite combination of UV (ultraviolet)-cured ethoxylated trimethylolpropane triacrylate macromer (serving as a mechanical framework) and Al2O3 nanoparticles (as a functional filler) in the presence of a high boiling point liquid electrolyte. A distinctive structural feature of the CPE is the close-packed Al2O3 nanoparticles in the liquid electrolyte-swollen ETPTA macromer matrix. Owing to this unique morphology, the CPE provides significant improvements in the mechanical bendability and suppression of lithium dendrite growth during charge–discharge cycling.

  • close packed poly methyl methacrylate nanoparticle arrays coated polyethylene separators for high power lithium ion polymer batteries
    Journal of Power Sources, 2011
    Co-Authors: Jang Hoon Park, Woong Park, Jonghun Kim, Dongjo Ryoo, Hoon Sik Kim, Yeon Uk Jeong, Dongwon Kim, Sang Young Lee
    Abstract:

    In an endeavor to improve the discharge C-rate performance of lithium-ion polymer batteries targeting high-power applications, we develop a novel gel polymer electrolyte-coated separator, which is based on introduction of close-packed poly(methyl methacrylate) (PMMA) nanoparticle arrays onto a polyethylene (PE) separator. In contrast to a conventional PMMA dense coating layer, a noticeable feature of the PMMA nanoparticle array coating layer is its highly ordered nanoporous structure, i.e. well-connected interstitial voids formed between the close-packed PMMA nanoparticles. This unique morphology allows for not only favorable liquid electrolyte wettability but also facile ionic conduction of the PMMA nanoparticle arrays-coated separator, both of which play crucial roles in improving the discharge C-rate performance of cells assembled with the separator.

  • close packed sio2 poly methyl methacrylate binary nanoparticles coated polyethylene separators for lithium ion batteries
    Journal of Power Sources, 2010
    Co-Authors: Jang Hoon Park, Woong Park, Jonghun Kim, Dongjo Ryoo, Yeon Uk Jeong, Joo Hyun Cho, Su Jin Yoon, Sang Young Lee
    Abstract:

    Abstract In an endeavour to improve not only the thermal shrinkage but also the electrochemical performance of separators in lithium-ion batteries, a novel composite separator is developed, i.e., a close-packed SiO2/poly(methyl methacrylate) (PMMA) binary nanoparticles-coated polyethylene (PE) separator. The introduction of SiO2 nanoparticles to the coating layer effectively suppresses thermal shrinkage of the composite separator. In contrast to a SiO2/PMMA coating layer having a film-shaped PMMA binder, the SiO2/PMMA binary nanoparticle coating layer employs PMMA particles as a binder. As a consequence, a highly porous structure, i.e., well-connected interstitial voids, is formed between the binary SiO2 and PMMA nanoparticles. The unique porous morphology allows favourable liquid electrolyte wettability and facile ionic conduction, which play a crucial role in improving cell performance such as the discharge capacity and the C-rate capability of the composite separator.

J S King - One of the best experts on this subject based on the ideXlab platform.

  • conformally back filled non close packed inverse opal photonic crystals
    Advanced Materials, 2006
    Co-Authors: J S King, Davy P Gaillot, Elton Graugnard, C J Summers
    Abstract:

    In this paper, we show that modification of PC-template topology by both heat treatment and multiple conformal infiltrations facilitates precise control and optimization of photonic-band properties. Static tuning is possible by precisely controlled backfilling of inverse opals to increase the filling fraction of dielectric material. [14] However, inverse opals have

Peter G Khalifah - One of the best experts on this subject based on the ideXlab platform.

  • mixed close packed cobalt molybdenum nitrides as non noble metal electrocatalysts for the hydrogen evolution reaction
    ChemInform, 2014
    Co-Authors: Bingfei Cao, Gabriel M Veith, Joerg C Neuefeind, Radoslav R Adzic, Peter G Khalifah
    Abstract:

    Co0.6Mo1.4N2 is synthesized by annealing CoMoO4 at 750 °C for 12 h under flowing NH3 followed by treatment at 400 °C for 1 h under flowing NH3.

  • mixed close packed cobalt molybdenum nitrides as non noble metal electrocatalysts for the hydrogen evolution reaction
    Journal of the American Chemical Society, 2013
    Co-Authors: Bingfei Cao, Gabriel M Veith, Joerg C Neuefeind, Radoslav R Adzic, Peter G Khalifah
    Abstract:

    A two-step solid-state reaction for preparing cobalt molybdenum nitride with a nanoscale morphology has been used to produce a highly active and stable electrocatalyst for the hydrogen evolution reaction (HER) under acidic conditions that achieves an iR-corrected current density of 10 mA cm–2 at −0.20 V vs RHE at low catalyst loadings of 0.24 mg/cm2 in rotating disk experiments under a H2 atmosphere. Neutron powder diffraction and pair distribution function (PDF) studies have been used to overcome the insensitivity of X-ray diffraction data to different transition-metal nitride structural polytypes and show that this cobalt molybdenum nitride crystallizes in space group P63/mmc with lattice parameters of a = 2.85176(2) A and c = 10.9862(3) A and a formula of Co0.6Mo1.4N2. This space group results from the four-layered stacking sequence of a mixed close-packed structure with alternating layers of transition metals in octahedral and trigonal prismatic coordination and is a structure type for which HER activ...

Andreas Stein - One of the best experts on this subject based on the ideXlab platform.

  • direct synthesis and pseudomorphic transformation of mixed metal oxide nanostructures with non close packed hollow sphere arrays
    Angewandte Chemie, 2018
    Co-Authors: Wenyang Zhao, Prashant Kumar, Xinyu Li, Yasser Al Wahedi, Andre K Mkhoyan, Michael Tsapatsis, Andreas Stein
    Abstract:

    : While bottom-up syntheses of ordered nanostructured materials at colloidal length scales have been successful at producing close-packed materials, it is more challenging to synthesize Non-Close-Packed (ncp) structures. Here, a metal oxide nanostructure with ncp hollow sphere arrays was synthesized by combining a polymeric colloidal crystal template (CCT) with a Pechini precursor. The CCT provided defined confinement through its tetrahedral (Td ) and octahedral (Oh ) voids where the three-dimensionally (3D) ordered, ncp hollow sphere arrays formed as a result of a crystallization-induced rearrangement. This nanostructure, consisting of alternating, interconnected large and small hollow spheres, is distinct from the inverse opal structures typically generated from these CCTs. The morphology of the ncp hollow sphere arrays was retained in pseudomorphic transformations involving sulfidation and reoxidation cycling despite the segregation of zinc during these steps.

  • tunable colors in opals and inverse opal photonic crystals
    Advanced Functional Materials, 2010
    Co-Authors: Carlos I Aguirre, Edilso Reguera, Andreas Stein
    Abstract:

    Colloidal photonic crystals and materials derived from colloidal crystals can exhibit distinct structural colors that result from incomplete photonic band gaps. Through rational materials design, the colors of such photonic crystals can be tuned reversibly by external physical and chemical stimuli. Such stimuli include solvent and dye infiltration, applied electric or magnetic fields, mechanical deformation, light irradiation, temperature changes, changes in pH, and specific molecular interactions. Reversible color changes result from alterations in lattice spacings, filling fractions, and refractive index of system components. This review article highlights the different systems and mechanisms for achieving tunable color based on opaline materials with close-packed or Non-Close-Packed structural elements and inverse opal photonic crystals. Inorganic and polymeric systems, such as hydrogels, metallopolymers, and elastomers are discussed.

Peng Jiang - One of the best experts on this subject based on the ideXlab platform.

  • biomimetic broadband antireflection gratings on solar grade multicrystalline silicon wafers
    Applied Physics Letters, 2011
    Co-Authors: Blayne M Phillips, Peng Jiang, Bin Jiang
    Abstract:

    We report a simple and scalable bottom-up technique for fabricating broadband antireflection gratings on solar-grade multicrystalline silicon (mc-Si) wafers. A Langmuir-Blodgett process is developed to assemble close-packed silica microspheres on rough mc-Si substrates. Subwavelength moth-eye pillars can then be patterned on mc-Si by using the silica microspheres as structural template. Hemispherical reflectance measurements show that the resulting mc-Si gratings exhibit near zero reflection for a wide range of wavelengths. Both experimental results and theoretical prediction using a rigorous coupled-wave analysis model show that close-packed moth-eye arrays exhibit better antireflection performance than Non-Close-Packed arrays due to a smoother refractive index gradient.

  • bioinspired broadband antireflection coatings on gasb
    Applied Physics Letters, 2008
    Co-Authors: Weilun Min, Peng Jiang, Amaury P Betancourt, Bin Jiang
    Abstract:

    We report an inexpensive yet scalable templating technique for fabricating moth-eye antireflection gratings on gallium antimonide substrates. Non-Close-Packed colloidal monolayers are utilized as etching masks to pattern subwavelength-structured nipple arrays on GaSb. The resulting gratings exhibit superior broadband antireflection properties and thermal stability than conventional multilayer dielectric coatings. The specular reflection of the templated nipple arrays match with the theoretical predictions using a rigorous coupled-wave analysis model. The effect of the nipple shape and size on the antireflection properties has also been investigated by the same model. These biomimetic coatings are of great technological importance in developing efficient thermophotovoltaic cells.

  • large scale fabrication of periodic nanostructured materials by using hexagonal non close packed colloidal crystals as templates
    Langmuir, 2006
    Co-Authors: Peng Jiang
    Abstract:

    This letter reports a versatile nonlithographic technique for mass fabricating three types of technologically important materialspolymer microwell arrays, 2D-ordered magnetic nanodots, and semiconductor nanopillar arrays, each with high crystalline qualities and wafer-scale sizes. Spin-coated hexagonal Non-Close-Packed silica colloidal crystals embedded in a polymer matrix are used as starting templates to create 2D polymeric microwell arrays. These through-hole arrays can then be used as second-generation templates to make periodic magnetic nanodots and semiconductor nanopillars. This self-assembly approach is compatible with standard semiconductor microfabrication, and complex micropatterns can be created for potential device applications. The wafer-scale technique may find important applications in biomicroanalysis, high-density magnetic recording media, and microphotonics.