CRITICAL ROLE OF SURFACES AND INTERFACES IN ENHANCING THE PERFORMANCE OF NANOSTRUCTURED SILICON-BASED ANODE MATERIALS FOR LITHIUM ION BATTERIES

摘要

Nanostructured silicon-based alloys and composites havenreceived great attention as a possible replacement of the conventionalncarbon-based anodes due to their higher lithium storage capacity. Innmany cases, however very little is known about their electrochemicalnproperties and microstructure evolution during lithiation, despitentheir importance for overcoming many technical hurdles faced innpractical use. Using first principles-based atomistic modeling, wenhave explored the lithiation behavior in various Si-basednnanostructures and nanocomposites including nanowires and Si-Cncomposites. This talk will present our recent progress, particularlynfocusing on addressing (1) the lithiation mechanisms of Si near thensurface and interface, with comparisons to those in bulk Si, and (2)nhow the surface and interface affects the performance of Si-basednnanomaterials as Li-ion battery anodes, such as charging rate andncapacity retention. Our study highlights that the presence of surfacesnand interfaces alters the lithiation behavior considerably; forninstance, the Li mobility along the surface or interface tends to bensignificantly enhanced by several factors. We will also present thensurface and interface effects on the structural evolution, bondingnmechanism, mechanical property, and voltage profile of lithiated Sinnanowires and Si-C nanocomposites. The improved understandingnmay offer important guidance for the rational design ofnnanostructured Si-based alloys and composites in order to maximizentheir capacity retention and rate capability.