Silicon monoxide (SiO) based materials are long-established high-capacity anode materials that are used in commercialized lithium-ion batteries. However, the inherently low initial Coulombic efficiency (ICE) is a hurdle to overcome, prior to their full potential utilization as anode materials for lithium-ion batteries. In this presentation, we demonstrate that the ICE of SiO can be enhanced to reach up to 90.5%, through a dehydrogenation-driven Li metal absent prelithiation method using lithium hydride (LiH). Released lithium that originates from LiH, preemptively forms lithium silicate phases, the main reason behind the low ICE of SiO. Through laser-assisted atom probe tomography (LA-APT) and scanning transmission electron microscopy (STEM), the formation of three-dimensionally networked Si/lithium silicate nanocomposite was visualized. The prelithiated SiO exhibits a capacity of 1203 mAh g^-1 with an ICE of 90.5% without detrimental alterations in electrochemical performance. The boost in ICE of prelithiated SiO results in a 50% enhancement of energy density of the full cell (37 mAh) compared to pristine SiO, with excellent cycle performance lasting for 800 cycles. Further description of the reaction mechanism and the resulting microstructure obtained through the suggested prelithiation will be discussed more in detail in the presentation.