Noon Sept. 11, SL-212
Ilias Belhaouek, Argonne National Laboratory
"Lithium-Sulfur: Current Status and Prospective"
The talk will review works on the room temperature lithium sulfur batteries since the year 2000. Namely, progresses in capacity, cycle life and efficiency of the cells will be discussed from science and engineering standpoints. The sulfur cathode in the Li-S battery offers superior theoretical capacity (1672 mAh.g-1) compared to all Li-ion battery cathodes. Li-S batteries have the advantages of using an abundant, nontoxic and low-cost cathode material. However, several performance-related issues prevent the development of practical Li-S batteries. These issues are rapid capacity fading and low coulombic efficiency, which are believed to be linked to the dissolution of lithium polysulfides from the sulfur electrode into the electrolyte. In this context, we will discuss our most recent results based on the development of a novel electrolyte that was designed to solve the cycling instability and inefficiency that are inherent to the Li-S battery. The new electrolyte consisted of lithium polysulfide species (Li2Sx) dissolved in dimethoxyethane solvent. This conceptually new approach is based on mitigating the sulfur loss by leveling the concentration gradient of the polysulfide species at the cathode/electrolyte interface. Therefore, when these species are produced at the cathode, they do not readily migrate into the electrolyte; instead, they are retained at the cathode interface.
11 a.m. Sept. 16, SL-212
Stephen Whitelam, Molecular Foundy, Lawrence Berkeley National Laboratory
"Nanoscale self-assembly and phase change at surfaces and in confinement"
Many important physical processes happen at surfaces or in confinement. I will discuss two examples, the first being the self-assembly of molecules on surfaces, the second being nucleation in pores. In the first example, I will show how a combination of quantum mechanics and statistical mechanics allows us to identify the physics that governs the self-assembly of small organic molecules into nonperiodic networks on a gold surface. I will also show that the same physics governs assembly of networks formed by a set of apparently unlike building blocks, which range in size from atoms to micron-scale polymers. In the second example, I will discuss how to predict where in a heterogeneous porous medium nucleation will happen. In both examples, simple features of geometry are key to determining the behavior of the system in question.
11:30 a.m. Oct. 9, SL-212 - Canceled due to the government shutdown
John Lemmon, Pacific Northwest National Laboratory
11:30 a.m. Oct. 23, SL-212
Arumugam Manthiram, Joe C. Walter Chair in Engineering and Director of the Texas Materials Institute and the Materials Science and Engineering Graduate Program, University of Texas at Austin
"Materials Challenges and Prospects of Electrical Energy Storage"
Electrical energy stored in batteries, particularly lithium-ion batteries, powers most of the modern portable electronic devices such as cellphones and laptops. Batteries are also being pursued intensively for electric vehicles and stationary storage of electricity produced by renewable sources like solar and wind. However, their adoption for transportation and stationary storage applications requires significant reduction in cost, long cycle life, increase in energy and power, and improvement in safety, which are in turn controlled by the component materials used in batteries. Clearly, development of new materials for existing battery technologies or new battery chemistries at an affordable cost with long life is needed to address our future energy needs. Accordingly, after providing an overview of the current status, this presentation will focus on the development of next generation of electrode materials for lithium-ion batteries as well as new battery chemistries such as hybrid dual-electrolyte lithium-air batteries.
Specifically, high-capacity, high-voltage oxide and high-capacity sulfur cathodes as well as safe nano-engineered alloy anodes for lithium-ion batteries will be first presented, emphasizing the importance of optimizing the surface and bulk structures and novel cell configurations to overcome the persistent problems in the field. Then, hybrid dual-electrolyte lithium-air cells in which the lithium anode in an organic electrolyte is separated by a solid electrolyte from the air electrode in an aqueous catholyte solution will be presented, emphasizing the development of buffer catholytes and inexpensive oxygen reduction and oxygen evolution electrocatalysts.
11:30 a.m. Nov. 6, SL-212
Christopher Prince, marketing application engineer, GE Digital Energy
"Seeing the Forest for the Trees"
The title is an idiom to say "You're so busy focusing on the one tree that you don't realize there's a whole forest."' "You are looking with blinders on."; or "There is so much more than what you see." The power grid has so many complexities and inter-relations that it's easier to break the problem down to the "trees" – but addressing the "forest" can be missed. The policymakers, the regulatory agents and the technology vendors have discreet influencing factors on the "forest" – yet the utility serves as the caretaker for the "trees," the ward of the "forest" and the mediator to the consumers – who derive the value in the direct products of the trees and the indirect benefits of the forest.
The title is a common and simple statement, yet not often used in the system engineering circles...let alone in the vernacular of the power grid. This presentation will present the fundamentals of the systems within an "organism" of supplying electrical power and then take a microscopic view to see the deeper and more extensive systemic relationships that must be considered to manage the most complex systems on the globe.
The objective of this discussion is to discover the opportunities for solutions that provide benefits across the entire system in an industry that is 130 years old -- but never more crucial to mature and growing societies.
11:30 a.m. Dec. 11, SL-212 (note new date)
Richard Wilson, Argonne National Laboratory
"Protactinium to Plutonium: Chemical Periodicity in the Actinide Elements"
The observed chemical behavior of the early actinide elements, Th to Am, is exceptionally diverse in comparison to the lighter lanthanide 4f series of elements. This is typified by the multitude of accessible oxidation states in the early actinide elements, trivalent to heptavalent, contrasting with the predominantly trivalent behavior of the lanthanide elements. This rich chemistry can be traced to the relative energetics of the valence orbitals, principally the 5f and 6d orbitals. The 5f orbitals become stabilized relative to the 6d orbitals upon moving from thorium across the series to americium. Importantly, the periodic stabilization of the 5f orbitals relative to the 6d's results in a crossing of the orbitals' relative energies at protactinium, the element between Th and U, making the chemical and spectroscopic properties of Pa, and heavier actinides, of potentially critical importance for understanding 5f electronic structure and bonding. Understanding and quantifying the chemistry of the actinide elements is paramount for developing nuclear energy technologies particularly as is relates to the exceptionally complex systems encountered in the nuclear fuel cycle. Recent results highlighting the effects of chemical periodicity on the early actinide elements encompassing trends in coordination chemistry, structure and spectroscopic properties will be presented.
This work is funded by the U.S. DOE Early Career Research Award program and was performed at Argonne National Laboratory for the U.S. DOE, OBES, Division of Chemical Sciences, Geosciences, and Biosciences, under contract DE-AC02-06CH11357.