Scientific Events

Host: on invitation of Prof. Dierk Raabe

Understanding (effective) ionic transport in solids and solid-state batteries

The advent of solid-state batteries has spawned a recent increase in interest in lithium conducting solid electrolytes. However, many open questions remain when trying to optimize electrolytes and understand solid state battery chemistries. In this presentation, we will show how an understanding of the structure-transport properties can help tailor the ionic conductivity. In an exemplary study on superionic lithium metal halides, we show that a cation site-disorder and the local structure of materials is important to study, especially as synthetic influences control materials properties. In a second part of this presentation, we will show the tremendous influence of lattice dynamics on ionic conductors. By introducing a different approach to understanding ionic motion using phonon occupations, we try to explain so far unexplained behaviors of physical ionic transport. Finally, we will show that it is not only important to find fast ionic conductors, but that fast ionic conduction is paramount within solid state battery composites. Measuring the effective ionic transport in cathode composites provides an avenue to explore transport and stability limitations that in turn provide better criteria for solid state battery performance Bio: Wolfgang Zeier received his doctorate in Inorganic Chemistry in 2013 from the University of Mainz. After postdoctoral stays at the University of Southern California, the California Institute of Technology, and Northwestern University, he was appointed group leader at the University of Giessen, within the framework of an Emmy-Noether research group. Since 2020 he holds a professorship for Inorganic Chemistry at the University of Münster. In addition, he heads a department at the Helmholtz-Institute Münster, Ionics in Energy Storage. His research interests encompass the fundamental structure-to-property relationships in solids, with a focus on thermoelectric and ion-conducting materials, as well as solid-solid interfacial chemistry for all-solid-state batteries. [more]

Metal fuels for zero-carbon heat and power

In order to address climate change, we must transition to a low-carbon economy. Many clean primary energy sources, such as solar panels and wind turbines, are being deployed and promise an abundant supply of clean electricity in the near future. The key question becomes how to store, transport and trade this clean energy in a manner that is as convenient as fossil fuels. The Alternative Fuels Laboratory (AFL) at McGill University is actively researching the use of recyclable metal fuels as a key enabling technology for a low-carbon society. Metal fuels, reduced using clean primary energy, have the highest energy density of any chemical fuel and are stable solids, simplifying trade and transport. The chemical energy stored in the metal fuels can be converted to useful thermal or motive power through two main routes: the Dry Cycle, where metal powders/sprays are burned with air, or the Wet Cycle, where metal powders are reacted with water to produce hydrogen and heat as an intermediate step before using the hydrogen as a fuel for various power systems. This talk will overview the concept of metal fuels and the various power system options. It will also touch on the combustion and reaction physics of metal fuels and the propagation of metal flames. Bio: Jeffrey Bergthorson is the Panda Faculty Scholar in Sustainable Engineering and Design, and a Professor in the Department of Mechanical Engineering, at McGill University where he leads the Alternative Fuels Laboratory. He received his B.Sc. in Mechanical Engineering from the University of Manitoba (1999), and his M.Sc. (2000) and Ph.D. (2005) in Aeronautics from the Graduate Aeronautical Laboratories of the California Institute of Technology. Prof. Bergthorson is a Fellow of the Combustion Institute and a Fellow of the American Society of Mechanical Engineers. Prof. Bergthorson’s research interests are in the broad area of the combustion and emissions properties of alternative and sustainable fuels, including biofuels, hydrogen, and the use of metals as recyclable fuels. [more]

Machine Learning for the Steel Industry: Behind the Buzzword

In 2020, every major company’s annual report contained the word digitalization, A.I. or industry 4.0. It is easy to perceive these as buzzwords, aimed at investors, but the reality is more complex: companies are expected to transform now, driven by the fear of becoming obsolete. As researchers, this exciting transition creates significant opportunities: huge amounts of data are becoming readily available, while computing power and machine learning (ML) algorithms are more accessible than ever. However, this is also leading to disproportionate hopes and expectations regarding the actual capabilities of such methods, that only a working knowledge of ML combined with technical expertise in your field can rationalize. As R&D engineers, this critical view will be expected from you. Since technical expertise has already been the focus of your professional career, the effort should therefore be put on acquiring a practical knowledge of ML, that is, what problems can be solved and how to solve them? In this talk, some applications of ML to solve industrial issues (predictive modeling, visualization, combination with physical models...) will be discussed. Furthermore, practical aspects, such as data preparation, models implementation and maintenance will be reviewed, with the aim of providing actual insights on the root causes of successes and failures of ML applied to the steelmaking process. [more]

Modelling the combustion of metal powders in laminar and turbulent flames

Besides their ubiquitous use in load-bearing structures, metals also possess qualities of energetic materials. Lithium, for example, is a common fuel in batteries, while aluminum is frequently added to solid rocket propellants and used in pyrotechnics. At high temperatures, metal powders can be burned in air in a similar way to hydrocarbon fuels, releasing chemically stored energy as sensible heat. Contrary to hydrocarbon combustion, however, the main reaction products are solid oxide particles that can, in principle, be retrieved from the exhaust fumes. This amenability to oxide sequestration has stimulated the idea of harnessing metal powders as recyclable energy carriers which are burned, retrieved and, subsequently, recharged by a reduction process based on clean primary energy. Conceptually, the metal powders are akin to high-temperature batteries, serving as a means to buffer the large spatial and temporal intermittency associated with renewable energy sources. Motivated by the potential use of metal powders as recyclable fuels, we qualitatively discuss the physical and chemical processes involved in the combustion of a single metal particle and of metal dusts, respectively. Subsequently, a population balance model for predicting the size distribution of the oxide smoke precipitating in the vicinity of a single burning aluminum particle is presented. Here, we specifically focus on the kinetic rates that control the phase transitions and smoke dynamics, integrating recently developed detailed kinetics for gas phase and heterogeneous surface reactions. The population balance equation governing the oxide size distribution is solved with the aid of a tailored adaptive grid method. An alternative, potentially more economical solution approach we propose is based on an embedded reduced order representation of the particle size distribution that is informed by a training step. The accuracy and convergence properties of this method are investigated for a simplified test case involving particle growth and dispersion in a laminar plane jet. In the final part of the seminar, the physical description, from an Eulerian viewpoint, of metal powders is discussed with a particular emphasis on the ramifications of carrier flow turbulence. In order to account for the small-scale interactions between dispersed particles and the ambient gas phase, the population balance equation governing the metal powder or oxide smoke is integrated into a probabilistic description that naturally accounts for the variability among independent realizations of a turbulent, particle-laden flow. Owing to the high dimensionality of the resulting transport equations, a stochastic solution approach based on Eulerian stochastic fields is proposed for which we show preliminary accuracy and convergence analyses.

Electrochemical Capacitance under Confinement: Implications for Electrochemical Energy Storage and Conversion

Electrochemical Capacitance under Confinement: Implications for Electrochemical Energy Storage and Conversion
Abstract: Many layered materials of interest for electrochemical energy storage and conversion applications are flexible hosts whose interlayers can be expanded to accommodate not just ions but also solvents, organic molecules, polymers, and organometallics. When these “hybrid” materials are placed into an electrochemical environment, the distinction between surface and bulk becomes blurred since the electrochemical interface can now be viewed to extend into the interlayer. During this seminar, I will discuss fundamental aspects of charge storage at electrochemical interfaces and how interfacial charge storage and reactivity change under confinement. I will also describe synthesis of hybrid layered materials and the use of in situ and operando characterization to understand the relationships between structure and composition and the resulting electrochemical reactivity. [more]

Metal energy carriers: renewable fuels of the future

Metal powder has superior energy density compared to fossil fuels and hydrogen. Therefore, metal powders have gained interest as a material for energy storage. The main benefits of metal fuels are that they do not produce CO2 emissions during combustion, they have the potential to be retrofitted in existing coal power plants and they can fit into the existing fuel transportation infrastructure. Furthermore, this enables the production of sustainable energy since metal fuels can be regenerated from metal oxides, using hydrogen from renewable sources. In this presentation, the main characteristics of metal fuels are presented with a final focus on clean combustion. A series of burners has been developed: - single particle or fuel jet in a micro burner to study single particle combustion and particle-particle interaction - Bunsen-type burner for stabilizing laminar and weakly turbulent premixed flames - Tornado-swirl burner First numerical studies are also started for comparison. Furthermore, a 100 KW demonstrator set-up is developed to demonstrate clean combustion to produce steam (placed at Swinkels brewery and Metalot centre). Studies to scale up are also conducted. The main objective of this practical systems is the development of an integrated flexible metal fuel burner with a capacity of 100 KW (TRL5). This is an essential step towards implementation of this sustainable technology. This project forms the basis to further develop full scale burners with a capacity of 10 MWth. The development of the prototype burner is executed by a consortium which covers the entire supply chain. This includes the production of metal powder, fuel preparation, burner and combusted product handling. The industrial partners have broad experience in metal powder supply, dense energy carriers and operating coal fired power plants. Furthermore, techno-economic analyses and the assessment of retrofit potential to existing assets will be carried out. Status-quo will be presented [more]

Growth of Mg-aluminate spinel at MgO- Al2O3 contacts: experiment, nature, and some theory

In this presentation the formation of spinel (MgAl2O4) by reaction between periclase (MgO) and corundum (Al2O3) is addressed. The reaction MgO + Al2O3 => MgAl2O4 may be regarded as a model case for diffusive phase transformations in oxide systems. All phases involved are moderately to highly refractory and have applications in ceramics. Above about 800°C, periclase and corundum react to form a layer of polycrystalline spinel at their interface. A pronounced dichotomy of the internal microstructure and texture of the spinel layer reveals the original position of the periclase-corundum interface. This reflects the direction and extent of the necessary Mg2+ and Al3+ transfer across the spinel layer and allows to quantify the underlying diffusion process. Systematic deviations of the Mg/Al ratio of the spinel from local equilibrium values at the spinel-periclase and the spinel-corundum interface are due to a finite mobility of the two reaction interfaces. The resistance against interface motion arises from dislocation climb at the periclase-spinel interface, which is complemented by the formation of Schottky defects in the reactant periclase. In contrast, the corundum-spinel interface moves by the glide of partial dislocations. This is energetically less expensive than the dislocation climb at the periclase-spinel interface and allows for comparatively rapid approximation of local equilibrium. [more]
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