P. Alex Greaney

Hydronium-Ion Batteries with Perylenetetracarboxylic Dianhydride Crystals as an Electrode

We demonstrate for the first time that hydronium ions can be reversibly stored in an electrode of crystalline 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA). PTCDA exhibits a capacity of 85 mAh g-1 at 1 A g-1 after an initial conditioning process. Ex situ X-ray diffraction revealed reversible and significant structure dilation upon reduction of PTCDA in an acidic electrolyte, which can only be ascribed to hydronium-ion intercalation. The lattice expansion upon hydronium storage was theoretically explored by first-principles density functional theory (DFT) calculations, which confirmed the hydronium storage in PTCDA.

Mg-Ion Battery Electrode: An Organic Solid’s Herringbone Structure Squeezed upon Mg-Ion Insertion

We report that crystalline 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA), an organic solid, is highly amenable to host divalent metal ions, i.e., Mg2+ and Ca2+, in aqueous electrolytes, where the van der Waals structure is intrinsically superior in hosting charge-dense ions. We observe that the divalent nature of Mg2+ causes unique squeezing deformation of the electrode structure, where it contracts and expands in different crystallographic directions when hosting the inserted Mg-ions. This phenomenon is revealed experimentally by ex situ X-ray diffraction and transmission electron microscopy, and is investigated theoretically by first-principles calculations. Interestingly, hosting one Mg2+ ion requires the coordination from three PTCDA molecules in adjacent columns of stacked molecules, which rotates the columns, thus reducing the (011) spacing but increasing the (021) spacing. We demonstrate that a PTCDA Mg-ion electrode delivers a reversible capacity of 125 mA h g-1, which may include a minor contribution of hydronium storage, a good rate capability by retaining 75 mA h g-1 at 500 mA g-1 (or 3.7 C), and a stable cycle life. We also report Ca2+ storage in PTCDA, where a reversible capacity of over 80 mA h g-1 is delivered.

Deterministic Phonon Transport Predictions of Thermal Conductivity in Uranium Dioxide With Xenon Impurities

We present a method for solving the Boltzmann transport equation (BTE) for phonons by modifying the neutron transport code Rattlesnake which provides a numerically efficient method for solving the BTE in its Self-Adjoint Angular Flux form. Using this approach, we have computed the reduction in thermal conductivity of uranium dioxide (UO

Coarse Grained Models of Heterogeneous Plasticity Using the Discrete Element Method—Bulk Metallic Glasses and Beyond

_2

Multiscale lattice Boltzmann modeling of two-phase flow and retention times in micro-patterned fluidic devices

) due to the presence of a nanoscale xenon bubble across a range of temperatures. For these simulations, the values of group velocity and phonon mean free path in the UO

Mechanism of Na-Ion Storage in Hard Carbon Anodes Revealed by Heteroatom Doping

_2

Insights on the Mechanism of Na-Ion Storage in Soft Carbon Anode

were determined from a combination of experimental heat conduction data and first principles calculations. The same properties for the Xe under the high pressure conditions in the nanoscale bubble were computed using classical molecular dynamics. We compare our approach to the other modern phonon transport calculations, and discuss the benefits of this multiscale approach for thermal conductivity in nuclear fuels under irradiation.

Corrigendum: Hydronium‐Ion Batteries with Perylenetetracarboxylic Dianhydride Crystals as an Electrode

Plastic deformation proceeds through a sequence of stochastic local slip followed by load redistribution. With continued deformation this builds up complex stress fields and develops a heterogeneous pat- tern of local strength, leading to the emergence of microvoids and cracks. The goal of this research is to develop a coarse grained model for crystal plasticity that captures the physics emergent form stochastic heterogeneous deformation. The method based on the discrete element method (DEM), an approach developed for modeling of granular materials and recently adapted for amorphous brittle solids. DEM models the material as a collection of interacting elements. The framework naturally captures the elastic coupling due to geometric frustration in a system under heterogeneous deformation and the emergent phenomena that develop from it. This paper presents the accomplishment of intermediate steps towards modeling crystal plasticity: modeling anisotropic elasticity, and modeling isotropic plasticity.

Automated design of flexible linkers

Abstract Recent advances for fabricating micro-featured architectures such as posts or pillars in fluidic devices provide exciting opportunities for multiphase flow management. Here we describe a novel, multiscale modeling approach for two-phase flows in microfeatured architectures developed within the Shan and Chen Lattice Boltzmann method. In our approach a fine scale is used to resolve the true microfeatured architecture, with a coarser scale used to model the gross geometry of the device. We develop the basic features of the approach and demonstrate its applicability to modeling retention times of droplets of a dispersed phase in an array of microposts – an architecture used in microfluidic reactors, bioreactors, and biomedical devises. Additionally we show that it is feasible to model the microfeatured geometry in a piecewise manner which includes extrapolating dispersed phase flow characteristics in the entire system based on simulations in smaller subdomains.