Impacts of vacancy-induced polarization and distortion on diffusion in solid electrolyte Li 3 OCl

2021 ◽  
Vol 379 (2211) ◽  
Author(s):  
Zerina Mehmedović ◽  
Vanessa Wei ◽  
Andrew Grieder ◽  
Patrick Shea ◽  
Brandon C. Wood ◽  
...  
Keyword(s):  
Solid Electrolytes ◽  
Host Lattice ◽  
Activation Energy Barrier ◽  
Local Distortion ◽  
Mobile Species ◽  
Complex Interactions ◽  
Diffusion Mechanisms ◽  
Dynamics Simulations ◽  
Fast Ion ◽  
Comprehensive Study

Lithium-rich oxychloride antiperovskites are promising solid electrolytes for enabling next-generation batteries. Here, we report a comprehensive study varying Li + concentrations in Li 3 OCl using ab initio molecular dynamics simulations. The simulations accurately capture the complex interactions between Li + vacancies ( V Li ′ ), the dominant mobile species in Li 3 OCl . The V Li ′ polarize and distort the host lattice, inducing additional non-vacancy-mediated diffusion mechanisms and correlated diffusion events that reduce the activation energy barrier at concentrations as low as 1.5% V Li ′ . Our analyses of discretized diffusion events in both space and time illustrate the critical interplay between correlated dynamics, polarization and local distortion in promoting ionic conductivity in Li 3 OCl . This article is part of the Theo Murphy meeting issue ‘Understanding fast-ion conduction in solid electrolytes’.

A New Phase of the Na+ Ion Conductor Na3PS4

2019 ◽  
Author(s):  
Theodosios Famprikis ◽  
James Dawson ◽  
François Fauth ◽  
Emmanuelle Suard ◽  
Benoit Fleutot ◽  
...  
Keyword(s):  
Solid Electrolytes ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Orthorhombic Crystal ◽  
Orthorhombic Crystal Structure ◽  
Ion Conductor ◽  
Solid State Batteries ◽  
Density Analysis ◽  
Two Phases ◽  
Dynamics Simulations

<div> <p>Solid electrolytes are crucial for next‑generation solid‑state batteries and Na<sub>3</sub>PS<sub>4</sub> is one of the most promising Na<sup>+</sup> conductors for such applications. At present, two phases of Na<sub>3</sub>PS<sub>4</sub> have been identified and it had been thought to melt above 500 °C. In contrast, we show that it remains solid above this temperature and transforms into a third polymorph, γ, exhibiting superionic behavior. We propose an orthorhombic crystal structure for γ‑Na<sub>3</sub>PS<sub>4</sub> based on scattering density analysis of diffraction data and density functional theory calculations. We show that the Na<sup>+</sup> superionic behavior is associated with rotational motion of the thiophosphate polyanions pointing to a rotor phase, based on <i>ab initio</i> molecular dynamics simulations and supported by high‑temperature synchrotron and neutron diffraction, thermal analysis and impedance spectroscopy. These findings are of importance for the development of new polyanion‑based solid electrolytes.</p> </div>

scholarly journals Molecular Dynamics Simulations of Crystal Nucleation near Interfaces in Incompatible Polymer Blends

Polymers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 347
Author(s):  
Wenlin Zhang ◽  
Lingyi Zou
Keyword(s):  
Molecular Dynamics ◽  
Polymer Blends ◽  
Md Simulations ◽  
Nucleation And Growth ◽  
Crystal Nucleation ◽  
Crystalline Order ◽  
Mobile Species ◽  
Deep Supercooling ◽  
Crystallizable Polymer ◽  
Dynamics Simulations

We apply molecular dynamics (MD) simulations to investigate crystal nucleation in incompatible polymer blends under deep supercooling conditions. Simulations of isothermal nucleation are performed for phase-separated blends with different degrees of incompatibility. In weakly segregated blends, slow and incompatible chains in crystallizable polymer domains can significantly hinder the crystal nucleation and growth. When a crystallizable polymer is blended with a more mobile species in interfacial regions, enhanced molecular mobility leads to the fast growth of crystalline order. However, the incubation time remains the same as that in pure samples. By inducing anisotropic alignment near the interfaces of strongly segregated blends, phase separation also promotes crystalline order to grow near interfaces between different polymer domains.

scholarly journals OH− and H3O+ Diffusion in Model AEMs and PEMs at Low Hydration: Insights from Ab Initio Molecular Dynamics

Membranes ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 355
Author(s):  
Tamar Zelovich ◽  
Mark E. Tuckerman
Keyword(s):  
Molecular Dynamics ◽  
Fuel Cell ◽  
Ab Initio ◽  
Cost Effective ◽  
Clean Energy ◽  
Proton Exchange ◽  
Ab Initio Molecular Dynamics ◽  
Anion Exchange Membranes ◽  
Diffusion Mechanisms ◽  
Dynamics Simulations

Fuel cell-based anion-exchange membranes (AEMs) and proton exchange membranes (PEMs) are considered to have great potential as cost-effective, clean energy conversion devices. However, a fundamental atomistic understanding of the hydroxide and hydronium diffusion mechanisms in the AEM and PEM environment is an ongoing challenge. In this work, we aim to identify the fundamental atomistic steps governing hydroxide and hydronium transport phenomena. The motivation of this work lies in the fact that elucidating the key design differences between the hydroxide and hydronium diffusion mechanisms will play an important role in the discovery and determination of key design principles for the synthesis of new membrane materials with high ion conductivity for use in emerging fuel cell technologies. To this end, ab initio molecular dynamics simulations are presented to explore hydroxide and hydronium ion solvation complexes and diffusion mechanisms in the model AEM and PEM systems at low hydration in confined environments. We find that hydroxide diffusion in AEMs is mostly vehicular, while hydronium diffusion in model PEMs is structural. Furthermore, we find that the region between each pair of cations in AEMs creates a bottleneck for hydroxide diffusion, leading to a suppression of diffusivity, while the anions in PEMs become active participants in the hydronium diffusion, suggesting that the presence of the anions in model PEMs could potentially promote hydronium diffusion.

scholarly journals Influence of Br − /S 2− site-exchange on Li diffusion mechanism in Li 6 PS 5 Br: a computational study

2021 ◽  
Vol 379 (2211) ◽  
Author(s):  
Marcel Sadowski ◽  
Karsten Albe
Keyword(s):  
Rotation Axis ◽  
Computational Study ◽  
Diffusion Mechanism ◽  
Range Transport ◽  
Site Exchange ◽  
Dynamics Simulations ◽  
Low Degrees ◽  
Fast Ion ◽  
Free Material ◽  
Superionic Conduction

We investigate how low degrees of Br − / S 2 − site-exchange influence the Li + diffusion in the argyrodite-type solid electrolyte Li 6 PS 5 Br by ab initio molecular dynamics simulations. Based on the atomic trajectories of the defect-free material, a new mechanism for the internal Li + reorganization within the Li + cages around the 4 d sites is identified. This reorganization mechanism is highly concerted and cannot be described by just one rotation axis. Simulations with Br − / S 2 − defects reveal that Li + interstitials ( L ii . ) are the dominant mobile charge carriers and originate from Frenkel pairs. These are formed because B rS . defects on the 4 d sites donate one or even two L ii . to the neighbouring cages. The L ii . then carry out intercage jumps via interstitial and interstitialcy mechanisms. With that, one single B rS . defect enables Li + diffusion over an extended spatial area explaining why low degrees of site-exchange are sufficient to trigger superionic conduction. The vacant sites of the Frenkel pairs, namely V Li   ′ , are mostly immobile and bound to the B rS . defect. Because S Br ′ defects on 4 a sites act as sinks for L ii . they seem to be beneficial only for the local Li + transport. In their vicinity T4 tetrahedral sites start to get occupied. Because the Li + transport was found to be rather confined if S Br ′ and B rS . defects are direct neighbours, their relative arrangement seems to be crucial for effective long-range transport. This article is part of the Theo Murphy meeting issue ‘Understanding fast-ion conduction in solid electrolytes’.

Sulfur doped Li1.3Al0.3Ti1.7(PO4)3 solid electrolytes with enhanced ionic conductivity and a reduced activation energy barrier

2020 ◽  
Vol 22 (30) ◽  
pp. 17221-17228
Author(s):  
Abdulkadir Kızılaslan ◽  
Mine Kırkbınar ◽  
Tugrul Cetinkaya ◽  
Hatem Akbulut
Keyword(s):  
Activation Energy ◽  
Ionic Conductivity ◽  
Energy Barrier ◽  
Solid Electrolytes ◽  
Activation Energy Barrier ◽  
Conductivity Enhancement

The mechanism of the ionic conductivity enhancement in sulfur-doped Li1.3Al0.3Ti1.7(PO4)3 (LATP) solid electrolytes.

scholarly journals The HMGB chromatin protein Nhp6A can bypass obstacles when traveling on DNA

2020 ◽  
Vol 48 (19) ◽  
pp. 10820-10831
Author(s):  
Kiyoto Kamagata ◽  
Kana Ouchi ◽  
Cheng Tan ◽  
Eriko Mano ◽  
Sridhar Mandali ◽  
...  
Keyword(s):  
Dna Binding ◽  
Single Molecule ◽  
Binding Proteins ◽  
Dna Binding Proteins ◽  
Binding Modes ◽  
Dna Structures ◽  
Bacterial Proteins ◽  
Associated Proteins ◽  
Diffusion Mechanisms ◽  
Dynamics Simulations

Abstract DNA binding proteins rapidly locate their specific DNA targets through a combination of 3D and 1D diffusion mechanisms, with the 1D search involving bidirectional sliding along DNA. However, even in nucleosome-free regions, chromosomes are highly decorated with associated proteins that may block sliding. Here we investigate the ability of the abundant chromatin-associated HMGB protein Nhp6A from Saccharomyces cerevisiae to travel along DNA in the presence of other architectural DNA binding proteins using single-molecule fluorescence microscopy. We observed that 1D diffusion by Nhp6A molecules is retarded by increasing densities of the bacterial proteins Fis and HU and by Nhp6A, indicating these structurally diverse proteins impede Nhp6A mobility on DNA. However, the average travel distances were larger than the average distances between neighboring proteins, implying Nhp6A is able to bypass each of these obstacles. Together with molecular dynamics simulations, our analyses suggest two binding modes: mobile molecules that can bypass barriers as they seek out DNA targets, and near stationary molecules that are associated with neighboring proteins or preferred DNA structures. The ability of mobile Nhp6A molecules to bypass different obstacles on DNA suggests they do not block 1D searches by other DNA binding proteins.

scholarly journals Preface to “A Commemorative Issue in Honour of Professor Nick Hadjiliadis: Metal Complex Interactions with Nucleic Acids and/or DNA”

2018 ◽  
Vol 19 (12) ◽  
pp. 3815
Author(s):  
Christina Banti ◽  
Sotiris Hadjikakou
Keyword(s):  
Nucleic Acids ◽  
Metal Complex ◽  
Special Issue ◽  
Complex Interactions ◽  
Comprehensive Study ◽  
Molecular Science

This Special Issue of the International Journal of Molecular Science comprises a comprehensive study on "Metal Complex Interactions with Nucleic Acids and/or DNA". [...]

Adsorption of water molecules on the surface of photo-catalyst: a first principles theoretical comparison between InVO4 and rutile TiO2

2002 ◽  
Vol 751 ◽  
Author(s):  
M. Oshikiri ◽  
M. Boero ◽  
J. Ye
Keyword(s):  
First Principles ◽  
Water Adsorption ◽  
Adsorption Process ◽  
Catalyst Surface ◽  
Chemical Reactivity ◽  
Water Molecules ◽  
Activation Energy Barrier ◽  
Reaction Proceeds ◽  
Adsorption Of Water ◽  
Dynamics Simulations

ABSTRACTThe adsorption process of water molecules on the surface of InVO4 has been investigated via first principles molecular dynamics simulations and compared with that of the well-known rutile TiO2. We have found that the surface of InVO4 shows a remarked chemical reactivity whenever comes in contact with water and H2O molecules are often adsorbed dissociatively on its surface. The reaction proceeds spontaneously in a way similar to the case of TiO2 and does not require the overcoming of an activation energy barrier. The peculiar atomic connectivity of the InVO4 bulk crystal structure and the changes at the catalyst surface induced by the water adsorption are discussed and compared with the TiO2 system.

Effective energy landscapes for mobile ions in solid electrolytes

2004 ◽  
Vol 835 ◽  
Author(s):  
Stefan Adams
Keyword(s):  
Activation Energy ◽  
Ion Transport ◽  
Solid Electrolytes ◽  
Transport Mechanism ◽  
Bond Valence ◽  
Trivalent Cation ◽  
Effective Energy ◽  
Energy Landscapes ◽  
Mobile Species ◽  
Mobile Ions

ABSTRACTBond valence mismatch landscapes may serve as simple models of the effective energy landscapes for mobile ions in solid electrolytes. Thereby they provide a tool to identify the ion transport mechanism and allow to predict the activation energy of the ionic conduction. Accounting for the mass dependence of the conversion from the BV mismatch into an activation energy scale yields a correlation that holds for different types of mobile cations. While in most cases the analysis of bond valence mismatch landscapes is consistent with the ion transport mechanism derived from experimental or other computational evidence, the presumed prototype of trivalent cation conductors Sc2(WO4)3 is discussed as an example, where the BV analysis of transport pathways suggests that the interpretation of previous experimental investigations has to be reconsidered. Both bond valence calculations and molecular dynamics simulations suggests that the most probable mobile species in stoichiometric Sc2(WO4)3 is neither Sc3+ nor individual O2- but the complex divalent anion WO42-.

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