The effect of various lithium sources such as LiCl, LiOH, and Li-metal on the microstructure and electrochemical properties of granulated SiO_x powders were investigated. Various lithium sources were metallurgically added for a passive pre-lithiation of SiO_x to improve its low initial coulombic efficiency. In spite of using the same amount of Li in various sources, as well as the same process conditions, different lithium silicates were obtained. Moreover, irreversible phases were formed without reduction of SiO_x, which might be from additional oxygen incorporation during the process. Accordingly, there were no noticeable electrochemical enhancements. Nevertheless, the Li₄SiO₄ phase changes the initial electrochemical reaction, and consequently the relationship between the microstructure and electrochemical properties of metallurgically pre-lithiated SiO_x could provide a guideline for the optimization of the performance of lithium ion batteries.