A5033052859- Crystallization and Solubility Studies
- X-ray Diffraction in Crystallography
- Advancements in Battery Materials
- Advanced Battery Technologies Research
- Advanced Battery Materials and Technologies
- Magnetic properties of thin films
- Theoretical and Computational Physics
- Electron and X-Ray Spectroscopy Techniques
- Semiconductor Quantum Structures and Devices
- Nanowire Synthesis and Applications
- Magnetic and transport properties of perovskites and related materials
- Extraction and Separation Processes
- ZnO doping and properties
- Analytical Chemistry and Sensors
- Magnetic Properties and Applications
- Advanced Condensed Matter Physics
- Semiconductor materials and interfaces
- Surface and Thin Film Phenomena
- Iron oxide chemistry and applications
- Metallic Glasses and Amorphous Alloys
- Neuroscience and Neural Engineering
- Solid-state spectroscopy and crystallography
- Ion-surface interactions and analysis
- Polymer Surface Interaction Studies
- Quantum Dots Synthesis And Properties
Heinz Maier-Leibnitz Zentrum
2015-2025
Technical University of Munich
2015-2025
Max Planck Computing and Data Facility
2015-2017
Helmholtz-Zentrum Berlin für Materialien und Energie
2011-2013
Freie Universität Berlin
2013
Forschungszentrum Jülich
2003-2005
Abstract Lithium metal batteries are next‐generation energy storage devices that rely on the stable electrodeposition of lithium during charging process. The major challenge associated with this battery chemistry is related to uneven deposition leads dendritic growth and poor coulombic efficiency (CE). A promising strategy for addressing utilizing a polymer coating anodic surface. While several works in past have evaluated coatings, requirements design still unclear. In work, effect dynamics...
Due to its high specific capacity, silicon is a promising candidate substitute conventional graphite as anode material in lithium-ion batteries. However, pure silicon-based anodes suffer from poor capacity retention, mainly due large volume change during cycling, which results pulverization and other side reactions. Therefore, alternative compositions with lowered content similar working voltage are favored, e.g. silicon-graphite (SiG), they can reduce these reactions while maintaining...
Lithium deposition on anode surfaces can lead to fast capacity degradation and decreased safety properties of Li-ion cells. To avoid the critical aging mechanism lithium deposition, its detection is essential. We present workflows for efficient Li electrode cell level. The are based a variety complementary advanced physico-chemical methods which were validated against each other both graphite graphite/Si electrodes: Electrochemical analysis, scanning electron microscopy, glow...
The step-flow growth mode is used to fabricate Si and Ge nanowires with a width of 3.5 nm thickness one atomic layer (0.3 nm) by self-assembly. Alternating deposition results in the formation nanowire superlattice covering whole surface. One Bi terminating surface distinguish between elements Ge. A difference apparent height measured scanning tunneling microscopy images for Also, different kinds two-dimensional Si/Ge nanostructures like alternating nanorings having 5-10 were grown.
Abstract The addition of Si compounds to graphite anodes has become an attractive way increasing the practical specific energies in Li‐ion cells. Previous studies involving Si/C lacked direct insight into processes occurring full cells during low‐temperature operation. In this study, a powerful combination operando neutron diffraction, electrochemical tests, and post‐mortem analysis is used for investigation 18650‐type cylindrical two different aging states are investigated by diffraction....
In this paper, we present an aging study of commercial 18650-type C/LiNi0.33Mn0.33Co0.33O2 lithium-ion cells. The test procedure comprises varying charging currents, discharging currents and resting times between cycles. cells show a nonlinear capacity fade after few hundred equivalent full cycles, if cycled with standard rate almost 1C, different times. By increasing the current or decreasing current, lifetime improves results in linear fade. neutron diffraction experiment reveals loss...
High voltage spinel is one of the most promising next-generation cobalt-free cathode materials for lithium ion battery applications. Besides typically utilized compositional range LixNi0.5Mn1.5O4 0 < x 1 in window 4.90-3.00 V, additional 1.5 mol Li per formula unit can be introduced into structure, an extended to 1.50 V. Theoretically, this leads significant increase specific energy from 690 1190 Wh/kg. However, utilization potential rapid capacity fading and polarization that lack a...
Li redistribution processes within Si-graphite composite (SiG) electrodes are analyzed using in situ and operando X-ray diffraction (XRD), ex light microscopy (LM), optical of cross-sectioned full cells (CS-IOM), 3D microstructure-resolved simulations cells. First, the lithiation behavior graphite SiG (Si content 20.8 wt.-%) is analyzed. The results used as validation methods (XRD, LM, CS-IOM, simulation). Second, between component Si investigated: By XRD measurements during charging...
Tungsten oxide <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:mrow><a:mo>(</a:mo><a:msub><a:mi>WO</a:mi><a:mi>x</a:mi></a:msub><a:mo>)</a:mo></a:mrow></a:math> films grown on tungsten (W) are characterized by depth-resolved Doppler-broadening spectroscopy (DBS) and positron-annihilation lifetime (PALS) as primary analytical methods. The <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"><b:msub><b:mi>WO</b:mi><b:mi>x</b:mi></b:msub></b:math> prepared W(111) monocrystals using...
Topologically stabilized spin configurations like helices in the form of planar domain walls (DWs) or vortex-like structures with magnetic functionalities are more often a theoretical prediction rather than experimental realization. In this paper we report on exchange coupling and helical phase characteristics within Dy-Fe multilayers. The hysteresis loops temperature show an bias field around 1.0 kOe at 10 K. Polarized neutron reflectivity reveal (i) ferrimagnetic alignment layers low...
Silicon-graphite (SiG) electrodes are attractive candidates as anodes for Li-ion batteries due to their high theoretical specific capacity. However, repeated lithiation/delithiation during charge/discharge cycling causes significant morphological changes of the silicon particles. This results in formation highly porous structures and severe side reactions at silicon/electrolyte interface. To quantify these changes, small-angle neutron scattering (SANS) was applied with selective contrast...
The controlled gold sputtering on quantum dot arrays forms nanostructures exclusively top of dots by self-assembly. A real time observation the nanostructure growth is enabled with grazing incidence small-angle X-ray scattering (GISAXS).
Self-organized anodic titania (TiO 2 ) nanotube arrays are an interesting model anode material for use in Li-ion batteries owing to their excellent rate capability, cycling stability and enhanced safety compared graphite. A composite where carbothermally treated conductive TiO nanotubes used as support a thin silicon film has been shown have the additional advantage of high lithium storage capacity. This article presents detailed comparison structure, surface bulk morphology self-organized...
We report on synthesis and investigation of nanocrystalline cobalt-iron-pyrites with an emphasis nanocrystal structure, morphology magnetic behavior. The nanocrystals (NCs) were 5-25 nm in diameter as characterized using scanning electron microscopy (SEM) transmission (TEM). With increase Fe fraction, X-ray diffraction small-angle-X-ray scattering (SAXS) showed a systematic decrease lattice constant, primary grain/NC size (15 to 7 nm), nanoparticle (NP) (70 20 respectively. temperature...
Grazing-incidence small-angle X-ray scattering is reported from nanoclusters in superparamagnetic (SPM) polycrystalline Co separated by Au. The self-organization of the form nanopillar-like structures with high perpendicular magnetic anisotropy. A distinct signature regular near-neighbour ordering observed, which commonly observed patterned nanostructures. estimated cluster sizes corroborate those their field response. Most significantly, SPM limit for these clusters can be raised to above...
The growth of kinetically self-organized 2D islands in Si/Si(111) epitaxy is described. island size distribution for this system was measured using scanning tunnelling microscopy (STM). influence surface reconstructions on kinetics studied directly a method simultaneous deposition and STM scanning. For the case Si Si(111), lateral rows width 7 × reconstruction unit cell at edges two-dimensional leads to formation 'magic' sizes. evolution shape individual {105} faceted Ge (hut clusters)...
Abstract Existence of 2 π -planar domain walls (DWs) are often reported for transition metal-rare-earth (TM/RE) layered systems. The magnetization process such two-dimensional randomly anisotropical system in the form -DWs is directly correlated with topologically stable helices. Here, instead TM/RE, we have investigated [Dy/Tb] 10 multilayers involving two different anisotropic layers rare-earth/rare-earth (RE/RE). Using and susceptibility as function temperature along thermo-remanent...
We realize a molecularly imprinted polymer (MIP) which is with the retinal neurotransmitter glutamate. The films prepared by electrochemical deposition have smooth surface granular morphology as observed using an atomic force microscope. Multiple reflection attenuated total infrared (ATR-FTIR) spectroscopy and X-ray photoelectron (XPS) are used to chemically confirm imprint of in MIP at solid–liquid solid–air interface, respectively. Fluorescence dye fluorescamine monitor changes...
We report on the effect of nonmagnetic spacer layers interface magnetism and exchange bias in archetypical [Co/CoO]${}_{16}$ system. The separation magnetic bilayers by Au with various thicknesses ${d}_{\mathrm{Au}}\ensuremath{\ge}25$ nm leads to a threefold increase field (${H}_{\mathrm{eb}}$). Reflectometry polarized neutrons does not reveal any appreciable change domain population. This result is agreement observation that granular microstructure within [Co/CoO] independent...
Training in exchange bias systems plays an essential role understanding the very origin of biasing effect. The nonequilibrium arrangement antiferromagnetic (AF) spins at antiferromagnetic-ferromagnetic interface, related to AF uniaxial anisotropy, a crucial during initial training. Our system choice, IrMn/CoFe, possesses softer anisotropy compared other (e.g., CoO), thereby reducing energy penalty due spins. Different methods have been applied initialize or modify unidirectional anisotropy....