First-principles study of surface and interfacial chemistry in silicon anodes

Silicon is a promising alternative to graphite as an anode material for lithium-ion batteries due to its enhanced safety and dramatically higher theoretical capacity. Drastic volume changes in silicon during lithiation and delithiation cycles, however, hinder capacity retention. Many successful strategies for improving the cyclability of silicon involve the engineering of interfacial chemistry and architectures, and to further these efforts, fundamental information on lithiation processes at well-defined silicon surfaces is greatly needed. In this talk, we present results of extensive computational modeling of interfaces in silicon anodes. Using first principles density functional theory (DFT), the thermodynamics and kinetics of lithiation on Si(111), Si(110), and Si(100) are investigated, and the intrinsic structure sensitivity of silicon lithiation is thereby determined. Different surface chemical species, arising from chemical treatments or surface segregation of bulk dopants, are also analyzed and shown to have significant effects on these lithiation processes.