Stability and Cyclability Predictions of Redox Active Organic Molecules for Non-Aqueous Redox Flow Batteries

Non-aqueous redox flow batteries (NaRFBs) are a promising technology for widespread grid-scale energy storage deployment. Despite their potential for high energy density, current active materials lack the necessary stability and cyclability for scale-up. One class of active materials for NaRFBs are redox active organic molecules (ROMs), which are a focus of recent development due to their low cost and high solubilities compared to other candidate active materials. The research in this thesis seeks to advance of ROM development through characterization of new active materials and development of computational design tools for stability and cyclability. ROM characterization focused on cyclability of the dialkoxyarene ROM catholyte family and (2,2,6,6-Tetramethylpiperidin-1-yl)oxyl (TEMPO). An extensive set of bulk electrolysis (BE) experiments with varying active material concentration, cycle rate, and supporting salt were performed. Two different design strategies for improving dialkoxyarene cyclability were identified: increasing steric hinderance in alkylammonium electrolytes and increasing lithium-coordination in lithium electrolytes. These two strategies and the BE data provide new insight into ROM design and proper selection of electrolytes for cyclability. Computational work used the model building tool Sure Independence Screening and Sparsifying Operator (SISSO) to develop models for screening and prediction of ROMs. A variety of prediction tools for dialkoxyarene and TEMPO cyclability were developed, highlighting the lowest unoccupied molecular orbital (LUMO) energy and the solvation energy as the most important active material descriptors for improving cyclability. Similar tools were developed for dialkoxyarene stability, with the LUMO energy and geometry as the most important factors identified by SISSO. Most significantly, a generalized screening model for stability was developed from data for dialkoxyarene catholytes and pyridinium anolytes. This model is the first generalizable model for any ROM property of interest and provides insight into the unknown factors affecting electrochemical stability. These models provide foundations and methods for the computational design of new ROMs.PHDChemical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/167994/1/bsilcox_1.pd

Annulated Dialkoxybenzenes as Catholyte Materials for Non‐aqueous Redox Flow Batteries: Achieving High Chemical Stability through Bicyclic Substitution

1,4‐Dimethoxybenzene derivatives are materials of choice for use as catholytes in non‐aqueous redox flow batteries, as they exhibit high open‐circuit potentials and excellent electrochemical reversibility. However, chemical stability of these materials in their oxidized form needs to be improved. Disubstitution in the arene ring is used to suppress parasitic reactions of their radical cations, but this does not fully prevent ring‐addition reactions. By incorporating bicyclic substitutions and ether chains into the dialkoxybenzenes, a novel catholyte molecule, 9,10‐bis(2‐methoxyethoxy)‐1,2,3,4,5,6,7,8‐octahydro‐1,4:5,8‐dimethanenoanthracene (BODMA), is obtained and exhibits greater solubility and superior chemical stability in the charged state. A hybrid flow cell containing BODMA is operated for 150 charge–discharge cycles with a minimal loss of capacity.A novel bicyclical substituted dialkoxy‐benzene molecule, 9,10‐bis(2‐methoxy‐ethoxy)‐1,2,3,4,5,6,7,8‐octahydro‐1,4:5,8‐dimethanenoanthracene (BODMA), is developed for use as catholyte materials in non‐aqueous redox flow batteries with greater solubility (in their neutral state) and improved chemical stability (in their charged state). A hybrid flow cell using BODMA demonstrates stable efficiencies and capacity over 150 cycles. The molecular design approach of BODMA can be inspirational for future development of redox active molecules.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/139992/1/aenm201701272.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/139992/2/aenm201701272-sup-0001-S1.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/139992/3/aenm201701272_am.pd

Concert recording 2019-11-20

[Track 1]. Quatour pour saxophones. I. Gaiete Villageoise / F. & M. Jeanjean -- [Track 2]. Memory from Nepomuk\u27s dances / Marcelo Zarvos -- [Track 3]. Quatour pour saxophones. II. Doloroso III. Spirituoso / P.M. Dubois -- [Track 4]. Danza 2016 / Lucky Chops -- [Track 5]. Howler back / Zack Browning -- [Track 6]. Dusk / Steven Bryant -- [Track 7]. Oileain reel / Craig Richards

Evolution of the patellar sesamoid bone in mammals

The patella is a sesamoid bone located in the major extensor tendon of the knee joint, in the hindlimb of many tetrapods. Although numerous aspects of knee morphology are ancient and conserved among most tetrapods, the evolutionary occurrence of an ossified patella is highly variable. Among extant (crown clade) groups it is found in most birds, most lizards, the monotreme mammals and almost all placental mammals, but it is absent in most marsupial mammals as well as many reptiles. Here, we integrate data from the literature and first-hand studies of fossil and recent skeletal remains to reconstruct the evolution of the mammalian patella. We infer that bony patellae most likely evolved between four and six times in crown group Mammalia: in monotremes, in the extinct multituberculates, in one or more stem-mammal genera outside of therian or eutherian mammals and up to three times in therian mammals. Furthermore, an ossified patella was lost several times in mammals, not including those with absent hindlimbs: once or more in marsupials (with some re-acquisition) and at least once in bats. Our inferences about patellar evolution in mammals are reciprocally informed by the existence of several human genetic conditions in which the patella is either absent or severely reduced. Clearly, development of the patella is under close genomic control, although its responsiveness to its mechanical environment is also important (and perhaps variable among taxa). Where a bony patella is present it plays an important role in hindlimb function, especially in resisting gravity by providing an enhanced lever system for the knee joint. Yet the evolutionary origins, persistence and modifications of a patella in diverse groups with widely varying habits and habitats—from digging to running to aquatic, small or large body sizes, bipeds or quadrupeds—remain complex and perplexing, impeding a conclusive synthesis of form, function, development and genetics across mammalian evolution. This meta-analysis takes an initial step toward such a synthesis by collating available data and elucidating areas of promising future inquiry

Engineering: Cornell Quarterly, Vol.07, No.3 (Autumn 1972): Seeing with Electrons and Ions

IN THIS ISSUE: The Chemical Nature of Atoms: A New Subject for Electron Microscopy /2 (John Silcox, director of the School of Applied and Engineering Physics at Cornell, describes the development of instrumentation and techniques that can provide a new kind of information on the structure of materials.) ... Electron Microscopy in the Study of Materials /9 (The director of Cornell's electron microscope facility at the College of Engineering, Stephen L. Sass, shows how the microscopic examination of specimens is used in studying the physical properties of materials.) ... High-Resolution Microscopy of Biomacromolecules: Present Limitations and Future Possibilities /14 (Cornell research that is extending the high-resolution capabilities of electron microscopy is discussed by Benjamin M. Siegel, professor of applied physics, in an article on the application of this technique to studies of biological interest, in particular the delineation of the ultrastructure of macromolecules.) ... Seeing With Ions: High-Resolution Magnification Without Lenses /21 (A high-resolution microscope in which ions rather than electrons create the image is discussed by David N. Seidman, associate professor of materials science and engineering. The field ion microscope, an instrument without lenses, permits the observation of individual atoms on the surface of a metal.) ... Register /30 (The appointment of Edmund T. Cranch to succeed Andrew Schultz, Jr., as College of Engineering dean is featured, and other staff and faculty appointments are covered.) ... Faculty Publications /4

Concert recording 2019-04-07c

[Tracks 1-3]. Janus / Paul Hayden -- [Tracks 4-5]. Duo sonata / Gregory Wanamaker -- [Tracks 6-7]. Ciudades. Sarajevo Addis Ababa / Guillermo Lago -- [Track 8]. Pit band / William Albright -- [Tracks 9-10]. Crossroads songs / Evan Chambers -- [Track 11]. I encourage the bickering / Dan Puccio

Toward Improved Catholyte Materials for Redox Flow Batteries: What Controls Chemical Stability of Persistent Radical Cations?

Catholyte materials are used to store positive charge in energized fluids circulating through redox flow batteries (RFBs) for electric grid and vehicle applications. Energy-rich radical cations (RCs) are being considered for use as catholyte materials, but to be practically relevant, these RCs (that are typically unstable, reactive species) need to have long lifetimes in liquid electrolytes under the ambient conditions. Only few families of such energetic RCs possess stabilities that are suitable for their use in RFBs; currently, the derivatives of 1,4-dialkoxybenzene look the most promising. In this study, we examine factors that define the chemical and electrochemical stabilities for RCs in this family. To this end, we used rigid bis-annulated molecules that by design avoid the two main degradation pathways for such RCs, viz., their deprotonation and radical addition. The decay of the resulting RCs are due to the single remaining reaction: O-dealkylation. We establish the mechanism for this reaction and examine factors controlling its rate. In particular, we demonstrate that this reaction is initiated by the nucleophile attack of the counteranion on the RC partner. The reaction proceeds through the formation of the aroxyl radicals whose secondary reactions yield the corresponding quinones. The O-dealkylation accelerates considerably when the corresponding quinone has poor solubility in the electrolyte, and the rate depends strongly on the solvent polarity. Our mechanistic insights suggest new ways of improving the RC catholytes through molecular engineering and electrolyte optimization

Redox Flow Batteries: Annulated Dialkoxybenzenes as Catholyte Materials for Non‐aqueous Redox Flow Batteries: Achieving High Chemical Stability through Bicyclic Substitution (Adv. Energy Mater. 21/2017)

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/139916/1/aenm201770121.pd