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

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. The migration energy barriers of lithium ions in SiO x /Fe@C were analyzed in four distinct directions, along with the corresponding lithium-ion diffusion sites.