Energy storage devices in many aerospace applications are facing unique challenges. Most of such applications, including remote surveillance, satellites, reusable launch vehicles, etc. depend on high-performance, highly specialized batteries. In Phase I, STI prepared and tested several sulfur-carbon nanocomposites of different formulations to identify parameters that affect composite performance characteristics. High efficient electrolyte solvent was prepared and demonstrated with high Coulombic efficiency and good cycling performance. During the Phase II, the composite's composition will be optimized further. Electrolyte solvent will be further optimized to increase the purity and Li ion conductivity. In parallel, cells with 500 mAh capacity will be designed and prototype batteries will be fabricated and characterized.