Understanding the properties and performance of Si-based alloys and composites for Li ion battery anodes through first principles-based atomistic modeling

Silicon has the greatest theoretical lithium storage capacity of any known materials. However, the practical use of Si anodes has not yet occurred because of their poor cycling performance, particularly related to significant volume changes during operation that cause electrode disintegration and rapid capacity fading. To overcome such problem, several studies have been undertaken to examine Si-based alloys and composites, yet our understanding of many fundamental aspects of the anode properties and performance remains insufficient. Using first principles-based atomistic modeling, we have explored the lithiation and delithiation behavior in various Si-based binary alloys (Si-M, M = active/inactive element) and nanostructured Si-C composite materials. This talk will present our recent progress, particularly focusing on addressing the effects of alloying on the structure and mechanical properties of host matrices and the anode structural evolution and capacity retention during repeated lithiation/delithiation. We will also discuss the behavior of Li in Si-C nanostructures.