Frontiers in Materials Science
2012
Prof. Yury Gogotsi
Distinguished University Professor and Trustee Chair
A.J. Drexel Nanotechnology Institute
Department of Materials Science and Engineering
Drexel University
"Carbon Nanomaterials for Capacitive
Energy Storage"
Friday, April 6, 2012
EMSL/1077
10:00AM
This seminar will provide an overview of our research activities in the area of nanostructured carbon materials with focus on supercapacitors and other energy-related applications. Supercapacitors are devices that store electrical energy electrostatically and are used in applications where batteries cannot provide sufficient power or chargedischarge rates. Until now, their higher cost, compared to batteries with similar performance, has been limiting the use of supercapacitors in many household, automotive and other cost-sensitive applications. This presentation describes the material aspects of supercapacitor development, addresses unresolved issues and outlines future research directions.
2011
Dr. Paul R. C. Kent
Staff Scientist
Oak Ridge National Laboratory
Center for Nanophase Materials Sciences
Computer Science and Mathematics Division
"Towards ab initio models of the solid
electrolyte interface and improved accuracy for energy related materials"
Tuesday, December 13, 2011
ETB Columbia River
Dr. Kent will discuss two distinct topics, the first relating to first principles modeling of electrolytes for lithium ion batteries, the second on quantum monte carlo methods, which offer significantly improved accuracy over the popular density functional approaches:
(1) The liquid electrolytes used in lithium ion batteries react on the battery electrodes, forming solid-electrolyte interphases (SEI). This results in capacity loss, an increase in cell resistance, and significantly alters the degradation mechanisms of the electrode materials. To help understand the SEI we have performed ab initio molecular-dynamics simulations of common carbonate electrolytes and lithium salts. We study the role of functionalization of graphiteanode edges on the reducibility of the electrolyte and the ease of Li-ion intercalation at the initial formation stages of the SEI. The molecular dynamics approach reveals, e.g., orientational ordering of the solvent molecules, and favored migration of inorganic (vs. organic) reductive components to the electrode.
(2) Despite recent improvements, practical density functional calculations lack accuracy when applied to many energy storage and catalytic materials. In the case of battery voltages, the challenge involves simultaneously obtaining accurate energies for an oxide and for a metal. Errors of 10% are common, suggesting also that diffusion barriers are suspect. Quantum Monte Carlo (QMC) is a method potentially offering much improved accuracy. However, QMC has only been broadly applied to molecules and select insulators. I will present very recent data for bulk aluminum and a variety of defects demonstrating excellent agreement with experiment, where such data is available. These developments, coupled with the availability of petascale computing, suggest QMC can serve as a benchmark for energy related materials.
Prof. Esther S. Takeuchi
SUNY Distinguished Professor
Chemical and Biological Engineering
Electrical Engineering
Chemistry
University at Buffalo
"Bimetallic Cathode Materials for Lithium Based Batteries"
Thursday, June 9, 2011
EMSL Auditorium - 3:45PM
Batteries for implantable cardiac defibrillators (ICDs) are based on the Lithium/Silver vanadium oxide (SVO, Ag2V4O11) system. This system was first implanted in 1987 and over 20 years later remains the dominant system used in human implants. Hundreds of thousands of lives have been saved due to ICDs powered by Li/SVO batteries. A case study highlighting the rich chemistry and electrochemistry of the Li/SVO system providing battery characteristics favorable to the ICD application will be discussed including strategies critical to successful commercialization.
We are currently investigating next generation materials with a general composition of MM'POx for possible application in biomedical batteries. Specifically, the first material under study is Ag2VO2PO4. Changes in the composition and structure of Ag2VO2PO4 with reduction, especially the formation of silver nanoparticles, are detailed to rationalize a 15,000 fold increase in conductivity with initial discharge, which can be related to the favorable battery characteristics associated with Ag2VO2PO4 cathodes.
Prof. Jingyue (Jimmy) Liu
Director, Center for Nanoscience
Professor, Department of Physics & Astronomy
Professor, Department of Chemistry & Biochemistry
"Nanostructures for Catalysis and Energy Production"
Friday, May 13, 2011
EMSL Auditorium - 1:30PM
Energy is not only the driver for improving the quality of human life but also critical to our survival. To power the planet for a better future, it is imperative to develop new processes for effective use of energy and to develop sustainable and clean energy resources. Catalysis, the essential technology for accelerating desired chemical transformations, plays an important role to realizing environmentally friendly and economically feasible processes for producing energy carriers and for converting them into directly usable energy. Design and synthesis of controlled nanostructures can help us address some key issues encountered in understanding the fundamental processes and dynamics of catalyzed reactions. We have recently synthesized both nanostructured metal oxides and shape-controlled metal nanocrystals, and applied them to the systematic investigation of catalytic processes for steam reforming of alcohols and the oxidation of carbon monoxide on nanoscale facets. Aberration-corrected scanning transmission electron microscopy techniques have been used to elucidate the atomic structures of the active phases. The ability of sub-Ångström resolution imaging with in situ capabilities available in a modern aberration-corrected TEM/STEM provides us excellent opportunities to study the dynamic behavior of nanostructures and to understand their synthesis-structure-performance relationships. Recent progresses in synthesizing novel metal oxide nanostructures for energy harvest and storage will also be discussed.
Joseph T. HuppJoseph T. Hupp
Department of Chemistry
Northwestern University
"Functional Metal-Organic Framework Materials"
Wednesday, May 4, 2011
EMSL Auditorium
1:30 PM
Permanently microporous and/or mesoporous metal-organic frameworks (MOFs) have commanded considerable recent attention. Among the reasons are the materials' high internal surface areas, uniform cavity and aperture size (for a given MOF material), and enormous potential compositional variety based on the chemistry of carbon.
Consisting of rigid or semi-rigid organic struts and metal-ion or metal-cluster nodes, MOFs are typically synthesized via solvothermal techniques. This presentation will touch upon very recent advances in MOF synthesis, advances in materials purification, and advances in materials activation. These advances, together with computational-modeling-assisted design, have enabled us to prepare a material (NU-100) displaying a molecule-accessible surface area of ca. 6,200 m2/g (> 1 square mile per pound). This value compares well with the molecule-accessible surface area promised by the single-crystal X-ray structure of NU-100. Together with another recently described framework material, MOF-210, this material exhibits the highest gravimetric surface area of any material synthesized to date.
Among other unusual properties, the high surface area of NU-100 engenders an extraordinarily high gravimetric capacity for uptake of molecular hydrogen at cryogenic temperatures: e.g. 77K and 70 bar, NU-100 displays a total capacity of 164 mg H2/1,000 mg MOF (= 14.3 wt. %) and an excess capacity (at 56 bar) of 99 mg H2/1,000 mg MOF (= 9.0 wt. %), the highest observed to date for a material storing molecular hydrogen. While these values are far above the targets proposed by the Dept. of Energy, they do not take into account the mass of additional systems components. Variable temperature measurements show that much less hydrogen is taken up at higher temperatures - a consequence of comparatively weak interactions between H2 and the framework material. Required going forward will be an approximate quadrupling of the strength of the interactions. Some approaches to this important problem will be discussed.
Finally, MOFs show promise for additional energy-related applications, including separations and multi-stage catalysis of chemical reactions. Highlights of some new developments in catalysis will be described, with particular emphasis on effective strategies for incorporating potentially highly potent active-sites into MOF environments.