Enhancing lithium storage performance with silicon-based anodes: a theoretical study on transition metal-integrated SiOx/M@C (M = Fe, Co, Ni) heterostructures

Abstract

In lithium-ion batteries, infusible metals with lithium, such as Mg, Fe, Co, Ni, and Cu are often utilized. However, current research predominantly focuses on the experimental aspects of the (de)lithiation process, with limited exploration from a theoretical calculation perspective. The extensive use of experimental methods to study the many electrochemically inert metals is time-consuming and costly. In this study, we successfully constructed and optimized SiO_x/M@C (M = Fe, Co, Ni) heterostructures, integrating transition metal nanoparticles to address the electrochemical inertness and slow diffusion kinetics of pristine SiO_x. A comprehensive density functional theory (DFT) study was conducted to examine the effects of different metal heterostructures on the structural, migration potential energy, and adsorption properties during lithium-ion intercalation. The results demonstrate that the SiO_x/Fe@C heterostructure exhibits the lowest migration energy barrier, significantly enhancing lithium-ion transport compared to SiO_x/Co@C and SiO_x/Ni@C. Consequently, the SiO_x/Fe@C electrode shows superior high-rate discharge capability and excellent cycling performance through electrochemical measurements. Additionally, the study delves into the intrinsic mechanisms through charge density differences and Fermi level calculations, providing valuable insights into the importance of hybrid strategies for incorporating inert metals into anode materials for lithium-ion batteries.