First-Principles Calculation of Lithium and Sodium Ion Diffusion in Crystalline Silicon Suboxide for Next-Generation Battery Anodes

Abstract

Silicon suboxides (SiO<inf>x</inf>, x < 2) are emerging as promising anode materials for lithium-ion and sodium-based batteries, especially when their oxygen content is minimized. These materials offer significant potential for advancing energy storage technologies by enabling various novel phases through electrochemical-induced solid-state amorphization and crystallization. This study utilizes first-principles simulations to investigate the structural evolution at lithiated and sodiated SiO<inf>2</inf>@Si surfaces, focusing on different crystalline orientations (SiO<inf>2</inf>@Si(110), (100), and (111)). Our results reveal that lithiation and sodiation processes are more favorable on the SiO<inf>2</inf>@Si(110) surface compared to the other orientations. Additionally, the ion transfer rate for Li⁺ increased from 7.62 × 10^-5 to 2.14 × 10^-4 cm²/s. These findings provide valuable insights into ion behavior at the atomistic level and suggest design principles for optimizing electrode materials by elucidating the mechanisms of partial oxide Si alloy formation across various anode architectures.