(23d) A Mechanistic Understanding of Lithium-Ion Diffusion and Intercalation in Novel Lignin-Derived Carbon Composite Anodes

Novel lignin-based carbon composite materials consisting of amorphous and crystalline domains have been developed for use as anodes in lithium-ion batteries.  The performance of these anodes is comparable to conventional anode materials at a significantly reduced manufacturing cost. However, the mechanism behind the performance of these novel materials is unknown. In this work, we develop an understanding of this mechanism through the use of reactive molecular dynamics simulations performed on computational models of the experimental systems. The coefficient of lithium-ion diffusivity in each domain and the degree of ion intercalation is ascertained as a function of ion-loading and related to structural properties of each composite system, including crystallite size, volume fraction of crystalline material, and composite density.  Voltage profiles of the model systems are compared to those obtained from experiment. The understanding of lithium-ion diffusion within these systems is used to formulate a prediction of an ideal combination of material properties that would allow the development of even higher performing composite anodes.

N.M. was supported by a grant from the Oak Ridge Associated Universities High Performance Computing Program, by a grant from the Sustainable Energy Education and Research Center of the University of Tennessee and by a grant from the National Science Foundation (DGE-0801470). This research project used resources of the National Institute for Computational Sciences (NICS) supported by NSF under agreement number: OCI 07-11134.5.  This research at Oak Ridge National Laboratory's Spallation Neutron Source was sponsored by the U.S. Department of Energy, Office of Basic Energy Sciences.