Filters

Settings

Now showing1 - 10 of 10
  • Some of the metrics are blocked by your 
    consent settings
    Item type:Project, Access status: without files ,
    Machine-Learned Force Fields for Lithium Manganese Oxide Cathode Materials
    Lithium manganese oxides (LMO) are promising cathode materials for lithium batteries. The transport properties crucial for battery performance are heavily dependent on the electronic structure and polarons, coupling the electronic structure with lattice distortions. While advanced X-ray scattering methods can, in principle, be used to investigate such properties, detailed knowledge of LMO is necessary to guide and analyze such experiments. Computational approaches can contribute significantly here. Traditionally, this requires sophisticated quantum mechanics calculations. However, accessible system sizes and time scales are limited using such methods. Thus, they often offer only an insufficient picture of the charging and discharging process. The development and training of a machine-learned force field (MLFF) for LMO has the potential to complete this picture. However, it requires a novel class of MLFFs that treat explicit charges in a way that accounts for long-range electrostatic interactions. Based on the charge equilibration (QEq) approach implemented in our ELECTRODE software package, we envisage incorporating charges into the MLFF. It is necessary to describe the short- and long-range order of extended polaronic structures in LMO. This study will support X-ray experiments to enable the tracking of lithium transport in LMO. Therefore, combining atomistic simulations with experiments would provide novel insights into this material and technological advancements.
      24
  • Some of the metrics are blocked by your 
    consent settings
    Item type:Project, Access status: without files ,
    From Plasticity to Entropic Recovery - Investigating Reversible Deformation Mechanisms in Thermosets through Spectroscopy and Molecular Modeling
    Epoxy resins generally behave rather brittle, but microscale samples show increased ductility. Thin epoxy films (<100 µm) exhibit pronounced ductility, localized shear bands and mechanically induced necking under tensile load. The formation of shear bands was identified as a cascade of macromolecular mechanisms involving polymer chain stretching, orientation and molecular bond stretching. This interplay of structural reorganizations under tensile loading characterizes the emergence of localized network adaptations and provides a central contribution to the understanding of ductile deformation. These findings raise fundamental questions about the physical prerequisites of plastic deformation in amorphous, close-meshed polymer networks. In particular, it must be clarified whether irreversible plastic network adaptations are involved or whether reversible viscoelastic relaxation processes predominate, which could be understood under thermal activation procedures. Epoxy films of different chemical compositions and reproducible sample thickness are investigated in terms of mechanical deformation using in-situ infrared spectroscopy. The focus is on spectral shifts of aromatic groups of the polymer backbones, especially within the para-substituted phenylene groups, which show stress sensitivity at the molecular level. The resulting peak shifts correlate with macroscopically visible deformation zones, which allow conclusions regarding intermolecular interactions, local orientation and potential network relaxations. Complementary to this, Molecular Dynamics Simulations, supported by AI-based spectrum predictions, allow a direct assignment of vibrations to intra- and intermolecular structural motifs. The elastic response of the polymer networks and thermally induced recovery processes are investigated. The targeted comparison of different network architectures allows an evaluation of the role of molecular connectivity and local mobility for the observed ductility. Temperature-controlled post-treatments are used to test the extent to which mechanically induced structural changes relax due to thermal activation and whether a complete regression of the initial state can be observed. The interplay of mechanical loading, molecular reorganization and thermal recovery facilitates to differentiate between reversible network mobility and irreversible plastic restructuring. The combination of experimental observations with simulation-based structure-property correlations enables a profound understanding of those molecular mechanisms. This knowledge creates the basis for the development of structurally adaptive, energy-absorbing and reusable thermoset materials for demanding technical applications.
      51
  • Some of the metrics are blocked by your 
    consent settings
    Item type:Project, Access status: without files ,
    EXC 3120 BlueMat - Research Topic B2: Selective Electrosorption
    Reversible electrochemical processes offer promising options in water treatment for removing oxyanions, dissolved organic carbon, and partial desalination by ion adsorption. Sorbent effectiveness depends on pore size, volume, surface area, and charge. However, current electrode fabrication processes limit control over multiscale porosity and surface charge, reducing their effectiveness in selective ion removal. Additionally, these properties are static, limiting adaptivity to avoid clogging and the ability to switch between adsorption and desorption. This RT advances the field by tailoring multiscale porosity of material systems for utilization as selective ion adsorbents and membrane filters. Innovative control of adsorption and desorption via adjustable surface potentials and selective ion sorption will transform materials into reversible, selective electrosorption systems. This facilitates strategic ion removal with low energy consumption, like lithium from seawater, marking a significant leap in harvesting engineering-valuable elements. The key scientific questions are: How can we functionalize 3D structured materials with locally and reversibly tunable adsorption and desorption of water-dissolved ions? How can we study the ion structure (+ hydration shell) and the spatiotemporal ion concentration evolution under electric potential and external flow, as well as the coupling of both, in a multiscale porous medium? How can we use multiscale modeling for functional optimization of materials for fast ion adsorption and desorption and low electrode degeneration rates resulting either in selective removal (water treatment) or selective ion (element) harvesting?
      65
  • Some of the metrics are blocked by your 
    consent settings
    Item type:Project, Access status: without files ,
    EXC 3120 BlueMat - Research Topic C4: Scattering of Visible Light by Control of Water Distribution
    Porous media with periodic or random structures comparable to the wavelength of light can provide spectrally selective scattering. Here, the optical response or color is no longer dictated by the base materials but by the pore shape, orientation, and arrangement, as well as by pore filling. Embedding water into the pore space and controlling its distribution at the nm- and ?m-scale allows for modifying the scattering, thus opening new possibilities to dynamically adjust or switch optical appearance. Previously, water has only been used to slightly shift the spectral response of periodic media upon water infiltration. However, here, we plan to go beyond this state of the art, achieving broadband control of the spectral response and even switching the color on and off. In this respect, we aim to achieve a similar functionality as in the skin of chameleons or cephalopods, but using water in porous media. The key scientific questions are: How can we design and fabricate structures with self-organized multiscale porosity to have defined optical appearance? How can we control water distribution in multiscale porous framework structures to switch this optical appearance? How can we utilize these effects for switchable structural color and opacity, including adaptive functionality?
      25
  • Some of the metrics are blocked by your 
    consent settings
    Item type:Project, Access status: without files ,
    EXC 3120 BlueMat - Research Topic D3: Hydrovoltaics
    BlueMat aims to revolutionize hydrovoltaics by developing next-generation hydrovoltaic material technologies. Our goal within D3 is to create high-performance, multiscale, porous materials and innovative hydrovoltaic device architectures to efficiently harness electrical energy from humidity variations, imbibition and drying cycles. We will systematically evaluate their energy conversion performance under varying humidity levels, temperatures, and operating conditions. Our research will focus on reducing imbibition–drying cycle times while enhancing energy output by leveraging humidity variations and low-grade waste heat. This interdisciplinary program aims to advance hydrovoltaics through cutting-edge experimentation, addressing key challenges, and unlocking new opportunities for sustainable energy generation from ambient environmental sources. We will develop highly adapted material architectures to optimize power, addressing issues like minimum friction, salt crystallization upon drying, or evaporation using aqueous electrolytes or water itself. The efforts in D3 aim to improve energy conversion efficiency, durability, and scalability of hydrovoltaic applications, paving the way for widespread deployment in diverse environmental settings. The key scientific questions include: How can we exploit novel hydrovoltaic mechanisms to generate energy from cyclic imbibition and desiccation of electrolyte-infused porous media? How do non-equilibrium fluid dynamics, surface chemistry, open-circuit potential, and other fundamental factors, including the interaction of imbibition and drying influenced by pore characteristics and external stimuli, affect the proposed scheme? How can we optimize the performance of the hydrovoltaic scheme using concepts like hierarchically porous electrodes and adaptive pore wall coatings?
      36
  • Some of the metrics are blocked by your 
    consent settings
    Item type:Project, Access status: without files ,
    EXC 3120 BlueMat - Cross Area Modeling
    The characteristic behavior of water-driven materials results to a large extent from complex and as yet often poorly understood interactions across different scales. To unravel the fundamental physics and chemistry of water-driven materials, (1) we will develop novel multiscale modeling methods bridging from the quantum to the device level; (2) machine learning (ML) will help to bridge between the scales and leverage the unique imaging data collected in the CA Imaging. Including physical knowledge into ML architectures will help accelerate the design of water-driven materials by identifying, for example, process-structure-property relationships in a fast and automated manner (physics-informed ML). To achieve these ambitious goals, we will rely on extensive (3) research software engineering, providing a whole ecosystem of cutting-edge open-source research software. Overall, we will create a unique multiscale and multi-purpose open-source software ecosystem for computer simulation and ML to understand, predict and optimize Blue Materials from the quantum level to the device level, laying the foundations to leverage cutting-edge imaging and AI to go from “nature-inspired materials” to materials and functionalities “beyond nature”
      55
  • Some of the metrics are blocked by your 
    consent settings
    Item type:Project, Access status: without files ,
    EXC 3120 BlueMat - Research Topic D1: Energy Storage in Supercapacitors
    We will create advanced electrochemical double-layer capacitors (EDLCs) using environmentally friendly materials and aqueous electrolytes. These supercapacitors, known for their rapid charging rates, high power density, and long cycle life, demand high-performance electrolytes and electrode materials. To prevent electrolyte decomposition, we will study high-concentration water-in-salt solutions and strong confinement. A combination of electrochemical studies, advanced in-situ/in-operando techniques, and molecular modeling will help us to understand the hydration/dehydration processes and ion transport dynamics, which are crucial for forming and structuring the EDL. Additionally, we introduce the consideration of the role of strong confinement on the electrolyte dielectric properties and optimize the microstructure of nanoporous carbons and clay-carbon composites to achieve highly energy-dense supercapacitors. Key scientific questions include: How does ion hydration influence EDL structure? Is there a specific dehydration mechanism for ions? How can ion-ion interactions be tuned, and how do they affect EDL formation? What is the impact of carbon porosity on the performance of waterin- salt electrolytes in EDLCs? Is there a correlation between the degree of carbon graphitization and EDL structure? How do the dielectric properties water and electrolyte solutions change with strong confinement in natural 2D materials?
      57
  • Some of the metrics are blocked by your 
    consent settings
    Item type:Project, Access status: without files ,
    EXC 3120 BlueMat - Research Topic D2: All-Water Redox Batteries
    D2 focuses on pioneering new battery solutions using water-based electrolytes and elucidating the critical interactions between water and aqueous electrolyte components at electrified interfaces. We will investigate the interactions between novel electrode materials and water within the context of battery technology. Our approach integrates advanced in-situ and in-operando characterization of material interfaces with modeling to bridge theoretical predictions and experimental observations. Such batteries use zinc metal anodes and cathodes with materials capable of intercalating anions. Dual ion batteries (DIBs) have a high energy density and relatively low cost, making them promising for use in various devices. By understanding the dynamic interactions of water within the pores of hierarchically structured cathode materials combined with layered double hydroxides (LDH), we aim to gain insights into the electrochemical performance and stability of these materials. On the anode side, we will explore the dynamic interactions of water during charge/discharge cycles and the effects of electrolyte additives on Zn dendrite formation. Key scientific questions include: What are new efficient electrolyte additives capable of controling charge/discharge processes on metallic Zn anodes? What is the mechanism at the atomistic scale? How can we develop the effective anion intercalation cathode assembled on hierarchically designed current collectors and open a pathway for the implementation of DIBs? What is the role of water in the ion-exchange processes and in the charge transfer within double hydroxide layers and in the interlayer spaces?
      56
  • Some of the metrics are blocked by your 
    consent settings
    Item type:Project, Access status: without files ,
    EXC 3120 BlueMat - Research Topic B3: Tunable Hydraulic and Capillarity-Driven Water Flow
    In conventional porous media, hydraulic permeability and capillary pressure during imbibition are determined by static geometry, water–solid interaction, and fluid viscosity. RT B3 aims to integrate mechanisms for stimulus-dependent changes in the pore size and solid- liquid interaction, resulting in tunable permeability and hydrophilicity-induced changes of local capillary forces. Combining this strategy with multiscale 3D structuring and local interface modification will enable materials that can locally and reversibly switch imbibition ability and kinetics. Challenges include the fabrication of multiscale 3D structures and precise hydrophilicity change at local levels. This RT focuses on understanding dynamic fluid–solid interactions upon reversible tuning by external stimuli in 3D multiscale porous structures. Key questions include: How can we explore the water–solid interfacial structure and measure the impact of tunable pore size and hydrophilicity on fluid transport? How can we tailor the flow and permeability rates by adjusting multiscale porosity (“Murray vascularization”) and response to stimuli? How can we fabricate structured 3D (nano)porous materials with locally and reversibly tunable permeability and hydrophilicity?
      40
  • Some of the metrics are blocked by your 
    consent settings
    Item type:Project, Access status: without files ,
    Sulfur-Aromatic Interaction in Biomolecules: Structural Investigations and Spectroscopy
    Jüngste bioinformatische Untersuchungen von Proteinstrukturdatenbanken haben ergeben, dass die Struktur eines Drittels aller bekannten Proteine durch nicht-kovalente Wechselwirkungen zwischen Schwefel und pi-Elektronen aromatischer Gruppen, so genannte S-pi-Wechselwirkungen, stabilisiert wird. Aufgrund der Veränderung der Elektronenorbitale sind die S-pi-Wechselwirkungsgruppen auch als Relaisstationen an den Elektronentransportprozessen innerhalb der Proteine beteiligt. Die biologische Relevanz dieser Wechselwirkung wird auch dadurch deutlich, dass sie bei Krankheiten eine Rolle spielt, die mit dem Verlust der Wechselwirkung aufgrund von Schwefeloxidation einhergehen, darunter altersbedingte Krankheiten wie Alzheimer oder Creutzfeldt-Jakob. S-pi-Wechselwirkungen gewinnen in vielen Forschungsbereichen an Interesse, etwa bei der Entwicklung neuer Medikamente für gezielte Therapien, beim Entwurf von Organokatalysatoren und beim Verständnis der Struktur und der Funktionen biologischer Systeme. Bislang gibt es jedoch keinen spektroskopischen Fingerabdruck dieser Wechselwirkung, der nicht nur Informationen über die elektronische Struktur, Ladungstransfers und abgeleitete Eigenschaften von schwefel- und aromatenhaltigen Proteinen liefert, sondern auch einen Biomarker für die Proteindenaturierung zur frühzeitigen Erkennung bestimmter Krankheiten darstellen könnte. Mit diesem Projekt zielen unsere Teams darauf ab, fortschrittliche Gasphasenspektroskopie-Instrumente (IR-, UV/VUV- und Röntgenspektroskopie) in Kombination mit massenspektrometrischen Techniken einzusetzen, um die Fingerabdrücke der S-pi-Wechselwirkungen in Peptiden und Proteinen zu entschlüsseln. Die grundlegenden Auswirkungen der Schwefeloxidation auf die Denaturierung des Proteins und die Veränderungen der spektroskopischen Signatur werden ebenfalls untersucht. Diese experimentelle Arbeit wird durch theoretische Berechnungen unterstützt, bei denen die S-pi-Wechselwirkung und der Rest des Moleküls durch ab initio-Methoden (QM) bzw. Molekularmechanik (MM) behandelt werden. Die Spektrenberechnung könnte auch Clustering-Techniken erfordern, um eine Schätzung der wichtigen Konformeren zu erhalten und so Schlüsselmerkmale für die Stabilisierung der Proteinstruktur durch S-pi-Wechselwirkungen zu ermitteln.
      73