The Korean Society of Surface Science and Engineering

Silicon (Si) is widely considered a promising anode material for high-energy-density lithium-ion batteries (LIBs) owing to its exceptionally high theoretical capacity (~3579 mAh g^-1) and natural abundance. However, its practical implementation is hindered by severe volume expansion and interfacial instability during lithiation, which result in electrode degradation and low initial coulombic efficiency (ICE). Silicon oxide (SiO_x) has emerged as a viable alternative, offering improved structural integrity and more stable cycling performance. Nevertheless, it still suffers from significant ICE loss due to irreversible lithium silicate formation and lithium trapping. Metal doping has recently gained increasing attention as an effective strategy to address these limitations. Incorporation of metal elements such as Mg, Sn, Ti, Li, into SiO_x has been demonstrated to enhance electrical conductivity, stabilize both the structure and the solid electrolyte interphase (SEI), and suppress the formation of electrochemically inactive phases-leading to improved ICE and prolonged cycle life. In this review, we provide a comprehensive summary of recent advances in metal doping strategies for SiO_x-based anodes. The focus is placed on doping mechanisms, synthesis methodologies, and their impact on structural and electrochemical properties, with an emphasis on practical feasibility for next-generation LIB applications.

Keywords SiO_x, Metal Doping, Anode Material, Initial Coulombic Efficiency, Lithium-Ion Battery, Commercialization