SI2-SSI Collaborative Research: A Computational Materials Data and Design Environment

This poster describes results associated with a project for the National Science Foundation, grant # 1148011. It was prepared for a PIs meeting on 2018-04-30. The primary results are <p>•The Materials Simulation Toolkit (MAST) for high-throughput defect and diffusion modeling</p> <p>•A Machine Learning extension (MAST-ML) to rapidly generate machine learning models from materials data.</p> <p>•Online defect and diffusion analysis apps on MaterialsHub.</p> <p>•The world’s largest computed and machine learning enhanced diffusion database with easy online search.</p> <p>•Valuable research results using these tools and data, e.g. new fuel cell materials.</p> <p>•Workforce training through the Informatics Skunkworks, an undergraduate materials informatics group.</p

SI2-SSI Collaborative Research: A Computational Materials Data and Design Environment

This poster describes results associated with a project for the National Science Foundation, grant # 1148011. It was prepared for a PIs meeting on 2018-04-30. The primary results are <p>•The Materials Simulation Toolkit (MAST) for high-throughput defect and diffusion modeling</p> <p>•A Machine Learning extension (MAST-ML) to rapidly generate machine learning models from materials data.</p> <p>•Online defect and diffusion analysis apps on MaterialsHub.</p> <p>•The world’s largest computed and machine learning enhanced diffusion database with easy online search.</p> <p>•Valuable research results using these tools and data, e.g. new fuel cell materials.</p> <p>•Workforce training through the Informatics Skunkworks, an undergraduate materials informatics group.</p

A database to enable discovery and design of piezoelectric materials

This JSON-file contains metadata pertaining to the compounds studied in this work and the associated calculated piezoelectric properties

Effect of Surface Microstructure on Electrochemical Performance of Garnet Solid Electrolytes

Cubic garnet phases based on Al-substituted Li₇La₃Zr₂O₁₂ (LLZO) have high ionic conductivities and exhibit good stability versus metallic lithium, making them of particular interest for use in next-generation rechargeable battery systems. However, high interfacial impedances have precluded their successful utilization in such devices until the present. Careful engineering of the surface microstructure, especially the grain boundaries, is critical to achieving low interfacial resistances and enabling long-term stable cycling with lithium metal. This study presents the fabrication of LLZO heterostructured solid electrolytes, which allowed direct correlation of surface microstructure with the electrochemical characteristics of the interface. Grain orientations and grain boundary distributions of samples with differing microstructures were mapped using high-resolution synchrotron polychromatic X-ray Laue microdiffraction. The electrochemical characteristics are strongly dependent upon surface microstructure, with small grained samples exhibiting much lower interfacial resistances and better cycling behavior than those with larger grain sizes. Low area specific resistances of 37 Ω cm² were achieved; low enough to ensure stable cycling with minimal polarization losses, thus removing a significant obstacle toward practical implementation of solid electrolytes in high energy density batteries

Effective and interactive dissemination of diffusion data using MPContribs, plus a demo of UW/SI2 and MPContribs

<p>We will describe in this talk how the general approach taken by MPContribs solves the very specific challenges faced by the UW researchers in effectively disseminating their data to the public. The presented solution developed in the collaborative effort between UW and LBNL is the first to demonstrate how MPContribs can empower research groups through the rapid development and deployment of customized but MP-compatible web applications either using on-site or MP resources. It will also be shown how these efforts directly translate into solutions for the ongoing collaboration with researchers at the Advanced Light Source at LBNL [1] in which we aim to develop a processing pipeline for experimental XAS data from the beamline computer to integrated analysis web apps on MP.</p><p>In our demo portion, we show the integration of the UW/SI2 workflow with MPContribs and JupyterHub. See [2] for a quick impression of the general functionality for the UW/SI2 use case. The video and the demo illustrate how MPContribs can be used to contribute, explore and feed data to the generic contribution details pages as well as a project-specific web application.</p><p>[1] MPContribs, arXiv:1510.05024, arXiv:1510.05727, MRS Spring 2016</p><p>[2] https://www.youtube.com/watch?v=wbWde5StHnU (3:43min)</p

Materials Design Rules for Multivalent Ion Mobility in Intercalation Structures

The diffusion of ions in solid materials plays an important role in many aspects of materials science such as the geological evolution of minerals, materials synthesis, and in device performance across several technologies. For example, the realization of multivalent (MV) batteries, which offer a realistic route to superseding the electrochemical performance of Li-ion batteries, hinges on the discovery of host materials that possess adequate mobility of the MV intercalant to support reasonable charge and discharge times. This has proven especially challenging, motivating the current investigation of ion mobility (Li⁺, Mg²⁺, Zn²⁺, Ca²⁺, and Al³⁺) in spinel Mn₂O₄, olivine FePO₄, layered NiO₂, and orthorhombic δ-V₂O₅. In this study, we not only quantitatively assess these structures as candidate cathode materials, but also isolate the chemical and structural descriptors that govern MV diffusion. Our finding that matching the intercalant site preference to the diffusion path topology of the host structure controls mobility more than any other factor leads to practical and implementable guidelines to find fast-diffusing MV ion conductors

Accelerating Electrolyte Discovery for Energy Storage with High-Throughput Screening

Computational screening techniques have been found to be an effective alternative to the trial and error of experimentation for discovery of new materials. With increased interest in development of advanced electrical energy storage systems, it is essential to find new electrolytes that function effectively. This Perspective reviews various methods for screening electrolytes and then describes a hierarchical computational scheme to screen multiple properties of advanced electrical energy storage electrolytes using high-throughput quantum chemical calculations. The approach effectively down-selects a large pool of candidates based on successive property evaluation. As an example, results of screening are presented for redox potentials, solvation energies, and structural changes of ∼1400 organic molecules for nonaqueous redox flow batteries. Importantly, on the basis of high-throughput screening, <i>in silico</i> design of suitable candidate molecules for synthesis and electrochemical testing can be achieved. We anticipate that the computational approach described in this Perspective coupled with experimentation will have a significant role to play in the discovery of materials for future energy needs

Lithium Diffusion in Graphitic Carbon

Graphitic carbon is currently considered the state-of-the-art material for the negative electrode in lithium ion cells, mainly due to its high reversibility and low operating potential. However, carbon anodes exhibit mediocre charge/discharge rate performance, which contributes to severe transport-induced surface structural damage upon prolonged cycling and limits the lifetime of the cell. Lithium bulk diffusion in graphitic carbon is not yet completely understood, partly due to the complexity of measuring bulk transport properties in finite-sized nonisotropic particles. To solve this problem for graphite, we use the Devanathan−Stachurski electrochemical methodology combined with ab initio computations to deconvolute and quantify the mechanism of lithium ion diffusion in highly oriented pyrolytic graphite (HOPG). The results reveal inherent high lithium ion diffusivity in the direction parallel to the graphene plane (∼10⁻⁷−10⁻⁶ cm² s⁻¹), as compared to sluggish lithium ion transport along grain boundaries (∼10⁻¹¹ cm² s⁻¹), indicating the possibility of rational design of carbonaceous materials and composite electrodes with very high rate capability

Three-Dimensional Growth of Li₂S in Lithium–Sulfur Batteries Promoted by a Redox Mediator

During the discharge of a lithium–sulfur (Li–S) battery, an electronically insulating 2D layer of Li₂S is electrodeposited onto the current collector. Once the current collector is enveloped, the overpotential of the cell increases, and its discharge is arrested, often before reaching the full capacity of the active material. Guided by a new computational platform known as the Electrolyte Genome, we advance and apply benzo­[<i>ghi</i>]­peryleneimide (BPI) as a redox mediator for the reduction of dissolved polysulfides to Li₂S. With BPI present, we show that it is now possible to electrodeposit Li₂S as porous, 3D deposits onto carbon current collectors during cell discharge. As a result, sulfur utilization improved 220% due to a 6-fold increase in Li₂S formation. To understand the growth mechanism, electrodeposition of Li₂S was carried out under both galvanostatic and potentiostatic control. The observed kinetics under potentiostatic control were modeled using modified Avrami phase transformation kinetics, which showed that BPI slows the impingement of insulating Li₂S islands on carbon. Conceptually, the pairing of conductive carbons with BPI can be viewed as a vascular approach to the design of current collectors for energy storage devices: here, conductive carbon “arteries” dominate long-range electron transport, while BPI “capillaries” mediate short-range transport and electron transfer between the storage materials and the carbon electrode

Discovery and Characterization of a Pourbaix-Stable, 1.8 eV Direct Gap Bismuth Manganate Photoanode

Solar-driven oxygen evolution is a critical technology for renewably synthesizing hydrogen- and carbon-containing fuels in solar fuel generators. New photoanode materials are needed to meet efficiency and stability requirements, motivating materials explorations for semiconductors with (i) band-gap energy in the visible spectrum and (ii) stable operation in aqueous electrolyte at the electrochemical potential needed to evolve oxygen from water. Motivated by the oxygen evolution competency of many Mn-based oxides, the existence of several Bi-containing ternary oxide photoanode materials, and the variety of known oxide materials combining these elements with Sm, we explore the Bi–Mn–Sm oxide system for new photoanodes. Through the use of a ferri/ferrocyanide redox couple in high-throughput screening, BiMn₂O₅ and its alloy with Sm are identified as photoanode materials with a near-ideal optical band gap of 1.8 eV. Using density functional theory-based calculations of the mullite Bi³⁺Mn³⁺Mn⁴⁺O₅ phase, we identify electronic analogues to the well-known BiVO₄ photoanode and demonstrate excellent Pourbaix stability above the oxygen evolution Nernstian potential from pH 4.5 to 15. Our suite of experimental and computational characterization indicates that BiMn₂O₅ is a complex oxide with the necessary optical and chemical properties to be an efficient, stable solar fuel photoanode