The research objective of this award is to elucidate the mechanisms of electro-chemically driven mechanical degradation in Si/C composite nanoelectrodes through an integrated experimental/computational approach. The nanoelectrodes consist of silicon nanocrystalline droplets deposited on the inner and outer surface of single-walled carbon nanotubes. This research has four tightly-integrated threads: i) develop first-principles based reactive force fields (ReaxFF) for Li-Si-C systems that enable large-scale atomistic simulations with quantum mechanical accuracy, ii) perform atomistic simulations with ReaxFF to extract basic thermodynamic properties of lithiated CNY and silicon nanodroplets as well as the kinetic parameters of lithium insertion, iii) develop an atomistically informed front-tracking finite element method to simulate and understand size-dependent morphological evolution, stress generation, and defect growth in nanoelectodes, and iv) perform in-situ electron microscopy studies of electrochemically driven deformation, defect nucleation, and growth at the nanoscale.
This research will contribute both cutting edge numerical simulations and nanoscale in-situ experiments of the complex, coupled electrochemical-mechanical phenomena that occur in battery electrodes and lead to degradation and ultimately loss of battery capacity. The research is highly interdisciplinary and will involve interactions and visits with Sandia National Laboratories for the participating students; this will expose them to cutting-edge experimental facilities.
