<p dir="ltr">This study investigates the electrochemical behavior of molybdenum disulfide (MoS₂) when utilized as an anode material in Li-ion batteries, particularly focusing on the intriguing phenomenon of extra capacity observed beyond theoretical expectations and the unique discharge curve of the first cycle. Employing a robust suite of advanced characterization methods such as in situ and ex situ X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM), the research unravels the complex structural and chemical evolution of MoS₂ throughout its cycling process. A pivotal discovery of the research is the identification of a distinct lithium intercalation mechanism in MoS₂, which leads to the formation of reversible Li_xMoS₂. These phases play a crucial role in contributing to the extra capacity observed in the MoS₂ electrode. Additionally, density functional theory (DFT) calculations have been utilized to explore the potential for overlithiation within MoS₂, suggesting that Li₅MoS₂ could be the most energetically favorable phase during the lithiation-delithiation process. This study also explores the energetics of a Li-rich phase forming on the surface of Li₄MoS2, indicating that this configuration is energetically advantageous and could contribute further to the extra capacity. The incorporation of reduced graphene oxide (RGO) as a conductive additive in MoS₂ electrodes, demonstrating that RGO notably improves the electrochemical performance, rate capability, and durability of the electrodes. These findings are supported by experimental observations and are crucial for advancing the understanding of MoS₂ as a high-capacity anode material. The implications of this research are significant, offering a pathway to optimize the design and composition of electrode materials to exceed traditional performance and longevity limits in Li-ion batteries.</p>