Nanostructured materials have attracted wide attention for energy storage. The reduced dimensions result in better accommodation of the strain associated with chemical and structural change, new reactions not possible in bulk materials, and high transport rates for ions and electrons. The high specific capacity (or capacitance) and improved reversibility are particularly attractive for batteries and supercapacitors. For practical applications, the electrochemical properties of both the electrode materials and the electrolytes need to be considered and investigated under appropriate reaction conditions desired for specific device applications. The interfacial chemistry and interfacial reactions play a particularly important role. The optimization of both the electrolyte and electrode materials, as well as new battery design are important for the development of new, low cost energy storage systems. Examples of such systems include new high energy redox flow batteries, Li-S and other metal-S batteries, and other conversion chemistry not reported before.