Lectures and Events - Department of Materials and Interfaces

Upcoming Lectures

  • December01

    14:00 PM

    Gerhard M.J. Schmidt Lecture Hall

    “Investigating the Surface Dynamics of Ions at the Anode-Electrolyte Interface using NMR Spectroscopy”

    Shakked Schwartz

    High-Performance, Rechargeable Li-ion Batteries (LIBs) are key to the global transition from fossil fuels to renewable...

    High-Performance, Rechargeable Li-ion Batteries (LIBs) are key to the global transition from fossil fuels to renewable energy sources. LIBs utilizing lithium metal as the anode are particularly exciting due to their exceptional energy density and redox potential, yet their advancement is hindered by growth of metallic filaments and unstable surface layers. Efficient cationic transport, which is crucial for battery performance, largely depends on the heterogeneous and disordered interphase formed between the anode and the electrolyte during cycling. Directly observing this interphase as well as the dynamic processes involving it is a great challenge. Here we present an approach to elucidate these dynamic processes and correlate them with the corresponding interfacial chemistry, focusing on the first step of cationic transport: surface adsorption. Employing Dark State Exchange Saturation Transfer (DEST) by 7Li NMR, we were able to detect the exchange of Li-ions between the homogenous electrolyte and the heterogeneous surface layer, highlighting the hidden interface between the liquid and solid environments. This enabled determination of the kinetic and energetic binding properties of different surface chemistries, advancing our understanding of cationic transport mechanisms in Li-ion batteries. 

  • January02

    11:00 AM

    Gerhard M.J. Schmidt Lecture Hall

    Graphullerene: a new form of two-dimensional carbon

    Dr. Elena Meirzadeh

    The two natural allotropes of carbon, diamond and graphite, are extended networks of sp3- and sp2- hybridized carbon...

    The two natural allotropes of carbon, diamond and graphite, are extended networks of sp3- and sp2- hybridized carbon atoms, respectively. By mixing different hybridizations and geometries of carbon, one could conceptually construct countless synthetic allotropes. In this talk, I will introduce graphullerene, a new two-dimensional superatomic allotrope of carbon combining three- and four-coordinate carbon atoms. The constituent subunits of graphullerene are C60 fullerenes that are covalently interconnected within a molecular layer, forming graphene-like hexagonal sheets. The most remarkable thing about the synthesis of graphullerene is that the solid-state reaction produces large polyhedral crystals (hundreds of micrometers in lateral dimensions), rather than an amorphous or microcrystalline powder as one would typically expect from polymerization chemistry. Similar to graphite, the crystals can be mechanically exfoliated to produce molecularly thin flakes with clean interfaces—a critical requirement for the creation of heterostructures and optoelectronic devices. We find that polymerizing the fullerenes leads to a large change in the electronic structure of C60 and the vibrational scattering mechanisms affecting thermal transport. Furthermore, imaging few-layer graphullerene flakes using transmission electron microscopy and near-field nano-photoluminescence spectroscopy reveals the existence of moiré-like superlattices. The discovery of a superatomic cousin of graphene demonstrates that there is an entire family of higher and lower dimensional forms of carbon that may be chemically prepared from molecular precursors.