Sodium-ion batteries (SIBs) have surfaced as an eminent contender to lithium-ion systems owing to sodium’s universal availability, economic viability, and ecological compatibility. This chapter delineates the scientific foundation and recent strides in SIB research, encompassing electrode architectures, electrolyte chemistries, and fabrication methodologies pivotal for augmenting performance and manufacturability. Electrochemical pathways governing Na-ion storage are critically analyzed in contrast with Li-ion counterparts, considering disparities in ionic radii, potential windows, and material adaptability. Cutting-edge cathodes—including layered transition-metal oxides—and diverse anode frameworks such as carbon derivatives and alloy-type materials are scrutinized with respect to their limitations in energy density, cyclability, and ion diffusion kinetics. The discourse extends to the evolution of liquid, gel, and solid-state electrolytes, underscoring their impact on conductivity enhancement and operational safety. Modern processing routes, including slurry casting and thin-film strategies, are evaluated for their applicability in compact and flexible device prototypes. Furthermore, the integration of nanotechnology is emphasized as a transformative tool for tailoring material properties and accelerating charge transport. Application horizons span from portable electronics and IoT modules to renewable-energy grids, though obstacles in long-term stability, volumetric energy, and large-scale synthesis persist. The chapter concludes by outlining futuristic avenues—ranging from hybrid and dual-ion chemistries to AI-driven material design—that hold promise for expediting the maturation of sodium-based energy storage into a sustainable and commercially viable technology.