(475f) Energetics, Structure, and Dynamics of Lignin-Based Carbon Composites
A new lignin-based carbon composite material composed of graphene-based nanoparticles distributed through an amorphous carbon matrix serves as a basis for novel lithium ion anodes. Experimentally synthesized materials show extraordinarily high ion capacity as well as excellent charging and discharging rates. It is hypothesized that the molecular-level basis for the observed improved performance is due to ion storage in the crystalline nanoparticles and rapid ion transport in the amorphous domain. In this work, a set of molecular-level models is proposed that is able to match experimental characterization for nanoparticle size, amorphous volume fraction, and overall density. Pair correlation functions (PCFs) from the well-characterized model systems are used to explain features of the experimental material obtained from the Advanced Photon Source and the Spallation Neutron Source. A complete suite of structural, thermodynamic, and dynamic properties have been generated, including d-spacing as a function of nanoparticle size, interplanar binding energies, and vibrational frequencies of planar breathing. Many of these properties are thought to be relevant for lithium intercalation. The impact on ion storage and transport is discussed.