Review on Improving the Performance of SiO_x Anodes for a Lithium-Ion Battery through Insertion of Heteroatoms: State of the Art and Outlook

Anode materials for Li-ion batteries have attracted significant research interest owing to the growing demand for efficient and cost-effective energy storage systems. Among the various anode materials being studied, silicon-based anodes have garnered considerable attention as a result of their potential to overcome many of the limitations associated with graphite anodes. However, silicon-based anodes undergo high volumetric expansion during cycling, which results in anode failure. In contrast, silicon-oxide-based (SiO_x) materials exhibit limited volumetric expansion, making them viable candidates as anode materials in lithium-ion batteries. Despite this, there remain several challenges associated with SiO_x anodes, including volumetric expansion (160-200%), poor capacity retention, and low initial coulombic efficiency. To address these issues, the incorporation of heteroatoms into SiO_x anodes has been proposed as a promising strategy. In this review, we aim to provide an overview of the current state of research on SiO_x anodes, including experiments and theoretical calculations, with a focus on the insertion of heteroatoms to improve the anode performance. In particular, we examine the effects of heteroatom incorporation on the anode conductivity, lithium diffusion, durability, and initial coulombic efficiency. In addition, we present a design strategy for the insertion of heteroatoms into the SiO_x anodes. This review aims to provide a comprehensive understanding of the role of heteroatoms in SiO_x anodes and highlight the potential for further research in this area.