Bulletin of the American Physical Society
APS March Meeting 2023
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session G45: Energy - Battery Electrolytes |
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Sponsoring Units: GERA Chair: Zeeshan Ahmad, Texas Tech University Room: Room 315 |
Tuesday, March 7, 2023 11:30AM - 11:42AM |
G45.00001: Probing Ionic Diffusion in Superionic Compounds Using Four-Dimensional Quasielastic Neutron Scattering Raymond Osborn, Stephan Rosenkranz, Matthew J Krogstad, Puspa Upreti, Anjana M Samarakoon, Daniel M Pajerowski Ionic mobility plays a central role in a wide range of energy-related technologies, whether in solid-state battery electrodes and electrolytes or as a mechanism for reducing thermal conductivity in thermoelectric compounds. The goal of optimizing the ionic conductivity for such applications requires an understanding of the microscopic diffusion pathways, residence times, activation energies, and the interplay between the mobile ion and the local relaxations of the surrounding lattice. Quasi-elastic neutron scattering (QENS) offers a direct method of probing ionic diffusion, providing diffusion coefficients, average residence times, and hopping lengths using jump diffusion models. Recent advances in single crystal inelastic neutron scattering now allow QENS to be measured in four-dimensional (Q,ω)-space. We will discuss measurements using CNCS at the Spallation Neutron Source of the fluorite compounds, SrCl2, within the superionic phase at 1050K, in which the Q-dependence of the linewidths of both incoherent and coherent scattering are sensitive to the self-correlation function and local relaxations around the hopping vacancies, respectively. |
Tuesday, March 7, 2023 11:42AM - 11:54AM |
G45.00002: The Role of Anti-Phase Domains in Enhancing Ionic Conductivity of Na-based Solid-State Battery Electrolytes Boyan K Stoychev All-solid-state batteries (ASSBs) are a promising alternative to current Li-ion systems, with the potential for significantly improved safety and energy density. Solid electrolytes require high ionic and low electronic conductivity, as well as electro-chemical and mechanical compatibility with electrodes. Both requirements remain a critical bottleneck for practical applications. Recently, our collaborators discovered that substituting Y3+ in Na3YCl6 with Zr4+ to form Na3-xY1-xZrxCl6 (NYZCx) enhances Na+ conductivity by two orders of magnitude, while simultaneously preventing electrochemical decomposition when paired with a NaCrO2 cathode. |
Tuesday, March 7, 2023 11:54AM - 12:06PM |
G45.00003: Effects of Anion Clusters at Solid-State Electrolyte and Electrode Interfaces Hong Fang, Purusottam Jena Stability and transport properties at the electrolyte-electrode interface are of great importance to the performance of all-solid-state batteries with solid-state electrolytes (SSEs). Most recent studies have shown that mono-/poly-anion clusters that are either original contained or doped in the SSE can lead to intriguing (transport, electronic, and mechanical) properties [1-6]. However, the effects of anion clusters on the SSE-electrode interfaces are unknown. Here, we will investigate such effects and unravel the working mechanisms using phase/reactivity analysis and explicit interface modeling. |
Tuesday, March 7, 2023 12:06PM - 12:18PM |
G45.00004: Simulations and Analyses of Li4 and Li6 (Thio)Boracites As Promising Li Ion Conducting Electrolytes for All-Solid-State Batteries Natalie Holzwarth, David Lynch, Yan Li The naturally occurring magnesium borate mineral, Mg3B7O13Cl, is characterized by a rigid framework of B-O bonds together with a regular void structure, ideally forming crystals in a face-centered cubic structure. Several structurally related fast Li ion conducting boracites and thioboracites have been synthesized, including Li4B7O12Cl [1], Li4Al3B4O12Cl [2], and Li6B7S13I [3]. In previous work [4], we have shown that the high ionic conductivity of all of these materials is related to the occurrence of natural interstitial Li sites due to the high symmetry of the crystalline structures. In this presentation, we report the results of computational analyses and simulations of the extended family of Li4 and Li6 ion-conducting (thio)boracites in predicted crystalline forms, including face-centered rhombohedral R3c structures of Li4B7S12Cl, Li6B7O13Cl, and Li6Al3B4O13Cl as well as a monoclinic Cc structure of Li6B7S13Cl. |
Tuesday, March 7, 2023 12:18PM - 12:30PM |
G45.00005: High entropy oxides: promising fillers for high ionic conductivity composite polymer electrolytes Juan Verduzco, Sebastian Calderon Cazorla, Gavin D Bidna, Alexander Wei, Alejandro Strachan, ERNESTO E MARINERO High entropy oxides (HEO) are promising materials for novel applications as they are known to exhibit ultra-high dielectric constants as well as high ionic conductivity when doped with lithium. The combination of these attributes renders HEOs attractive as nano-fillers in composite polymer electrolytes (CPE). We report on the synthesis of (MgCoCuZn)O, (MgCoNiCuZn)O, and Lix(MgCoNiCuZn)1-xO utilizing a sol-gel method in combination with high temperature annealing followed by fast quenching to attain single rock salt crystalline order of these HEOs. Nanoparticles are fabricated employing ball milling and different weight loads are incorporated into polymer-salt matrixes. In this talk we will report on ongoing measurements and results on the structural properties of the HEOs and the CPEs as well as ion transport measurements. |
Tuesday, March 7, 2023 12:30PM - 12:42PM |
G45.00006: Reaction and Ionic Migration at the Electrode-electrolyte Interface in Solid State Batteries from Machine Learning Molecular Dynamics Jingxuan Ding, Boris Kozinsky Understanding the interfacial reactions between the Li-metal anode and solid-state electrolyte (SSE) and the Li ion diffusion mechanism are keys for developing stable and efficient solid-state batteries. Yet, theoretic studies are hindered by the high computational costs of ab initio molecular dynamics in both spatial and temporal dimensions. We combine on-the-fly active learning based on Gaussian Process regression (FLARE) with local equivariant neural network interatomic potentials (Allegro) to construct a symmetric battery of Li-metal anode and SSE and perform machine-learned molecular dynamics (MLMD) of tens of thousands of atoms over several nanoseconds with ab initio accuracy. Prominent reactions are observed at the interface with product phases forming a transition layer spanning a few tens of angstroms. Li ions near the interface are observed to migrate from the anode into the electrolyte and eventually diffuse within the SSE. Finally, we examine how off-stoichiometry affects the reaction rate of the interface and enhances Li ion diffusion. |
Tuesday, March 7, 2023 12:42PM - 12:54PM |
G45.00007: Visualizing Unstable Lithium Electrodeposition within Polymer-ceramic Composite Electrolytes Vivaan Patel Solid polymer and perovskite-type ceramic electrolytes have both shown promise in advancing solid-state lithium metal batteries. Despite their favorable interfacial stability against lithium metal, polymer electrolytes face issues with dendrite formation due to their low ionic conductivity and poor mechanical strength. Highly conductive and mechanically robust ceramics, on the other hand, can be unstable against pure lithium metal. To overcome the disadvantages of each material, we incorporate Li0.33La0.56TiO3 (LLTO) nanoparticles into a block copolymer, polystyrene-b-polyethylene oxide (SEO), matrix to develop a polymer-composite electrolyte (SEO-LLTO). We use synchrotron hard x-ray microtomography to noninvasively study the cell failure and interfacial stability of SEO-LLTO in a lithium-lithium symmetric cell. We observe no clear trend in ionic conductivity or current fraction with increased nanoparticle loading. While the SEO-LLTO electrolyte demonstrates a higher storage modulus than SEO, it is unable to sustain large current densities due to dendrite formation. Three-dimensional tomograms reveal the formation of large globular lithium structures preferentially around regions of high LLTO concentrations in contact with lithium metal. However, upon repeated cycling at lower current densities, the formation of similar globular dendritic structures is not observed. Moreover, by encasing the SEO-LLTO between layers of SEO, we prevent direct contact of LLTO with lithium metal, allowing for the passage of seven-fold higher current densities without signatures of lithium deposition around LLTO. We posit that in addition to direct contact of LLTO and lithium metal, there exists a relatively low critical current density that induces interfacial instabilities in these polymer-composite electrolytes. |
Tuesday, March 7, 2023 12:54PM - 1:06PM Author not Attending |
G45.00008: Effect of reference frame and ion-pair lifetime on the transport coefficients of polymer electrolytes Yunqi Shao, Harish Gudla, Daniel Brandell, Chao Zhang The transport coefficients of electrolyte solutions are important design parameters for electrochemical energy storage devices. The experimental measurements and simulations thereof help to understand the factors limiting the performance of electrolyte materials. We demonstrate the critical role of reference frame (RF) in reconciling the recent experimental observation of negative transference numbers in the polymer electrolyte PEO-LiTFSI, and establishing the link between experiment and simulation. We show that the quantitative comparison of transport coefficients is only possible upon proper RF transformation, and highlight the impact of anion mass fraction and anion-anion interaction on the reported transference numbers. By tuning the solvent polarity of the polymer electrolyte, we reveal two regimes characterized by different ion-pair lifetime with distinct ion-pair kinetics and ion-ion correlation. |
Tuesday, March 7, 2023 1:06PM - 1:18PM |
G45.00009: Free energy sampling to understand the effect of local ion coordination in polymer electrolytes on transport properties Siddharth Sundarararaman, David Prendergast, Ana Sanz Matias, Fabrice Roncoroni In order to understand the success of polyethylene oxide (PEO) for lithium-ion batteries and explore possible better alternatives for salt-polymer mixtures, we study various ions at different concentrations in poly(ether-acetal) electrolytes [P(nEO-mMO), where EO is ethoxyl and MO is methoxyl]. Free-energy sampling, using metadynamics with tailored interaction potentials, elucidates the various coordination environments of ions and the energetic pathways for ion transport in these systems. Using cleverly chosen collective variables, we gain insight into: (1) the competition between cation-anion pairing and coordination by the different polymers at various concentrations, (2) the relative stabilities of single- vs. multi-chain coordination environments and (3) the impact of multi-chain coordination on the glass transition temperature and associated ion transport. We also use advanced data-mining approaches to classify the diverse set of configuration environments buried in these simulations, gaining a deeper understanding of local coordination environments that might easily have been missed with manual inspection. Armed with this insight we suggest strategies for electrolyte design to improve ion transport in battery applications. |
Tuesday, March 7, 2023 1:18PM - 1:30PM |
G45.00010: Collective ion dynamics in Organic Ionic Plastic Crystals Ivan Popov, Alexei P Sokolov Organic ionic plastic crystals (OIPCs) appear to be promising materials to replace conventional liquid electrolytes in solid state batteries. OIPCs, in contrast to liquid electrolytes, exhibit low conductivity, preventing them to be widely used. Recent investigations have shown that despite of high ion mobility even in their solid phases, the DC-conductivity is significantly suppressed by strong ion-ion interactions [1, 2]. In this study we conducted broadband dielectric spectroscopy, light scattering, and NMR diffusion investigations in the sample Hexafluorophosphate - Diethyl(methyl)(isobutyl)phosphonium [PF6][P1,2,2,4] in order to better understand the causes of the ion-ion correlations in OIPCs. We discovered two types of ion dynamic in OIPCs: i) at short times and length scale the ion dynamic in crystalline phase is similar to regular ionic liquids, ii) while at longer scale 1.5-2 nm, the ion-ion correlations suppress charge displacement and DC conductivity. DC conductivity regime is achieved only when ions are diffusing more than 1.5-2 nm. |
Tuesday, March 7, 2023 1:30PM - 1:42PM |
G45.00011: Fully Characterizing an Electrolyte for Lithium - Ion Batteries Using Electrochemical Methods and Electrophoretic NMR Darby Hickson, David Halat, Alec S Ho, Jeffrey A Reimer, Nitash P Balsara Improvements in current lithium - ion battery electrolytes are necessary to accomodate future energy storage needs. The electrolyte facilitates ion transport, and the transport properties of the electrolyte can be studied using Newman's concentrated solution theory. In this, the electrolyte is fully characterized by a thermodynamic factor and three transport parameters, conductivity, diffusion coefficient, and the transference number. The transference number is obtained by combining multiple electrochemical parameters, which can result in large error bars that obscure the transport behavior of the electrolyte. To reduce this error, we have used electrophoretic NMR (eNMR) to directly measure the electric-field-induced ion and solvent velocities to determine the transference number. This additionally enables the determination of the thermodynamic factor with greater certainty. The relevant transport and thermodynamic parameters have been studied in this work for a liquid electrolyte, lithium bis(trifluoromethanesulfonyl)imide dissolved in tetraethylene glycol dimethyl ether. Based on these results, it is evident that a combination of electrochemical methods and electrophoretic NMR can fully characterize liquid electrolytes for lithium-ion batteries with greater certainty. |
Tuesday, March 7, 2023 1:42PM - 1:54PM |
G45.00012: Correlated Ion Transport in High-Concentration Electrolytes Sheng-Lun Liao Ion transports in the organic solvents with low permittivity, which is often used as electrolytes in lithium ion batteries, are strongly correlated. Recent evidences suggested that the strong couplings between ions and solvents in the high-concentration regime (>1M) can result in a negative correlation between the molar conductivity and self-diffusivity of lithium ions, in sharp contrast to the expectation based on the Nernst-Einstein relation. We calculate the full Onsager transport coefficients using all-atom molecular dynamics simulation over a wide range of concentrations, and decouple the contributions from self-diffusivity and ion-ion correlation. The results show that, in the dilute regime, the oppositely charged species are more likely to move collectively, which causes negative contribution to conductivity; in the concentrated regime, clusters are more abundant, which facilitates ionic hopping between neighboring solvation shells. These two competing effects lead to the salient peak in molar conductivity observed in both experimental and simulation data. Finally, we show that the correlations of ion transport decrease with increasing concentration by examining the variation of the Haven ratio with ion concentration. |
Tuesday, March 7, 2023 1:54PM - 2:06PM |
G45.00013: Ab initio molecular dynamics for calculating battery voltage Manuel Smeu The voltage of a battery can typically be simulated with density functional theory (DFT) by calculating the Gibbs free energy difference between the charged and discharged components. For typical battery chemistries, this can be reasonably approximated with the energies of the cathode and anode, while the electrolyte is considered to experience no net change. However, there are some instances where the electrolyte plays an active role in the operation of the battery. This presentation will describe our efforts to calculate the voltage of batteries in which the state (composition) of the electrolyte changes during the charge/discharge process, which needs to be treated with ab initio molecular dynamics (AIMD) to capture the dynamical nature of liquid electrolyte, and to calculate its contribution to the voltage. In one example, we study a battery that involves dual ion (de)-intercalation of both Na+ and ClO4- species into the cathode. A second example involves vanadium redox flow batteries in which all electrochemical processes occur within the liquid anolyte and catholyte. The approach described here is transferrable to study numerous other battery chemistries in which the liquid electrolyte plays an active role. |
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