To enhance the development of improved lithium-ion batteries, one must gain a comprehensive understanding of the decomposition reactions and reaction by-products of electrolyte solutions. Despite substantial efforts spanning several decades, comprehending the formation of Solid Electrolyte Interphase (SEI) remains a challenging task. In this study, we conducted a comparative analysis of electrolyte decomposition processes occurring in graphite and carbon-coated SiOx anodes. Furthermore, we performed cycling tests on three different electrolyte formulations: those containing VC, those containing FEC, and those devoid of any additives. Our findings confirm that electrolyte decomposition takes place during the charging and discharging cycles, resulting in uneven electrode surface changes. Importantly, the nature of these surface changes depends on the active material and additive conditions. Notably, VC and FEC additives demonstrate effectiveness in mitigating specific reactions involving electrolyte solvents. However, it is worth noting that electrolyte decomposition continues throughout the charging and discharging process, persisting until the latter half of the cycle.