In recent years, the search for new electrode materials for rechargeable Li-ion batteries has undergone a drastic shift toward nanomaterials. A similar tendency is expected to occur for the conceptually similar Na-ion batteries. Due to very short internal diffusion paths, nanoscale materials are far less limited by their ionic or electronic conductivities than their bulk counterparts. Nanomaterials can also withstand much greater mechanical deformation during charge/discharge cycling. Overall, these favorable effects significantly enlarge the variety of inorganic compounds that can be used as Li and Na ion storage media. Herein, we discuss the perspectives of a specific family of nanomaterials-monodisperse colloidal nanocrystals and nanoparticles-for controlling and studying the effects of size, composition, and morphology on electrochemical properties. Despite clear scientific advantages, commercialization of such nanomaterials is presently hampered by their high cost of synthesis, owing to the use of organic solvents and coordination compounds.