Bulletin of the American Physical Society
APS March Meeting 2020
Volume 65, Number 1
Monday–Friday, March 2–6, 2020; Denver, Colorado
Session U40: Physics and effects on transport of ion-ion correlation in electrolyte materials IIFocus
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Sponsoring Units: DCOMP DCP DMP Chair: Arthur France-Lanord, Massachusetts Institute of Technology MIT Room: 705 |
Thursday, March 5, 2020 2:30PM - 3:06PM |
U40.00001: Ion-ion correlations across and between micropores in carbon electrodes Invited Speaker: Trinidad Méndez-Morales Graphene nanostructures can be the solution for maximizing the capacitance and improving the performance of electrical double-layer capacitors [1]. Also, ionic liquids (IL) can be considered for optimizing these devices owing to some of their unique properties [2]. The combination of both is expected to be key for the development of supercapacitors with high energy density and long cycling life [3]. |
Thursday, March 5, 2020 3:06PM - 3:18PM |
U40.00002: Ion and solvent dynamics in ‘solvent-in-salt’ electrolytes Ivan Popov, Robert Sacci, Nicolette Sanders, Naresh C Osti, Eugene Mamontov, Takeshi Kobayashi, Marek Pruski, Ray Matsumoto, Matt Thompson, Peter Thomas Cummings, Alexei Sokolov Recently, the solvent-in-salt (SIS) systems have attracted significant attention as a perspective electrolytes for the next generation of high voltage batteries and supercapacitors. In this study we analyzed ion and solvent dynamics in highly concentrated solutions in water and acetonitrile of two similar salts Li- TFSI and Li-FSI. We performed comprehensive study of bulk properties using Broadband dielectric spectroscopy (BDS), quasielastic neutron scattering (QENS), NMR, FTIR, and MD simulations. The results revealed that even small amount of solvent leads to high ionic conductivity. Moreover, the conductivity of FSI systems is always greater than the TFSI systems. Analysis reveals that the high conductivity is provided by high solvent mobility even in these very concentrated salt solutions, and higher mobility in the FSI systems is caused by weaker anion-solvent interactions. Presented results suggest that FSI based systems are more promising for use in electrical energy storage systems. |
Thursday, March 5, 2020 3:18PM - 3:30PM |
U40.00003: Electroneutrality Breakdown in Nanoporous Membranes Pedro De Souza, Amir Levy, Martin Bazant The transport of ions in charged membranes underlies a number of important technologies in separations, electrochemistry, and energy harvesting. In general, the charge selectivity and conductivity performance characteristics of the membranes arise from the fixed charge on the membrane, the concentrations of salt, and the size of the pores. Here, we identify unique characteristics of electrostatic screening in 1D nanopores, and demonstrate how these screening properties can affect conductivity and selectivity of membrane systems. In particular, we show that in extreme 1D confinement, the screening length in a nanopore is exponentially long, approaching macroscopic length scales, and can eclipse even the length of extremely long nanotubes. The long-range 1D screening results in the phenomenon of electroneutrality breakdown, where the number of charges within the pore does not match the number of charges on the pore walls, since a significant fraction of the electric field can escape through the pore walls into the membrane matrix. Electroneutrality breakdown has strong consequences on selectivity and conductivity, because the number of mobile charges inside the pore determines these parameters. |
Thursday, March 5, 2020 3:30PM - 3:42PM |
U40.00004: Atomic Scale Characterization of the Voltage-Dependent Electrical Double Layer Structure Katherine Harmon, Felipe Jimenez-Angeles, Sang Soo Lee, Michael J Bedzyk, Monica Olvera De La Cruz, Paul Fenter The adsorption of ions at charged surfaces into an electrical double layer (EDL) is a driving factor in many phenomena including energy storage, nanoparticle stabilization, and biomolecule transport. The ability to control these processes relies on a detailed understanding of the atomic-scale interactions at play. Several EDL models with different assumptions have been proposed, including the diffuse ion cloud of Gouy-Chapman (GC) theory and complex ion-ion correlation phenomena. However, significant debate persists over the accuracy and limitations of these theories. Direct experimental probes of the structures at different surface charges can help to elucidate many open questions. Here, we use in situ resonant anomalous X-ray reflectivity (RAXR) to study the EDL structure of Rb+ at a graphene/SiC electrode in aqueous 0.1 M RbCl as a function of applied potential. The results are compared to molecular dynamics (MD) predictions. Differences in RAXR and MD results are evaluated in the context of GC and ion-ion correlation theories with an eye on the possibility of overcharging at the most negative potentials. |
Thursday, March 5, 2020 3:42PM - 3:54PM |
U40.00005: Ionic liquid dynamics measured with implanted-ion β-NMR Derek Fujimoto, Ryan M. L. McFadden, Martin H Dehn, Yael Petel, Aris Chatzichristos, Lars Hemmingsen, Victoria L. Karner, Robert F Kiefl, Philip C. P. Levy, Iain McKenzie, Carl Michal, Gerald Morris, Matt Pearson, Daniel Szunyogh, John Ticknor, Monika K Stachura, W Andrew MacFarlane Ionic liquids (ILs) not only found in a wide range of potential applications, spanning energy storage to space travel, but the constituent ions have fascinating dynamics and structure. In this study, we use implanted-ion 8Li β-NMR to probe these dynamics in the IL 1-ethyl-3-methylimidazolium acetate. Sensitivity to nanosecond 8Li+ solvation dynamics is inferred from the motional narrowing of the resonance and the local maxima in the 8Li relaxation rate. We show that the activation energy and Vogel-Fulcher-Tammann temperature associated with the relaxation process agree with the dynamic viscosity. Near the melting point, the lineshape is broad and intense, and the form of the relaxation is non-exponential, reflective of heterogeneous dynamics. This demonstration establishes the feasibility of studing the local structure and dynamics of IL thin films and interfaces using β-NMR1. |
Thursday, March 5, 2020 3:54PM - 4:06PM |
U40.00006: Fundamental Studies of Tritium Diffusivity in Irradiation Defective LiAlO2 and Li2ZrO3: A Frist Principles Density Function Theory Study Hari Paudel, Yuhua Duan The thermal neutron irradiation of lithium isotope (6Li) in tritium (3H) -producing burnable absorber rods (TPBARS) of LiAlO2 and Li2ZrO3 crystal produces vacancies, defects of its constituent elements, and several different trapping sites which hinder tritium diffusion process and releasing behavior. Here we investigate the diffusion mechanisms of tritium and O3H species in LiAlO2 and Li2ZrO3 ceramic pellet in order to understand and quantify the effects on diffusion barriers and diffusion coefficients due to the presence of interstitial and substitutional Li defects, hydroxide (O-3H) vacancy defect, and the interactions of 3H with O-vacancies in Li2ZrO3. We find the smallest activation energy barriers of 0.63 and 0.3 eV in LiAlO2 and Li2ZrO3, respectively. The obtained results indicate that the performance of Li2ZrO3 could be better than a widely used ceramic in TPBAR, γ-LiAlO2. |
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