High efficiency power systems are needed for NASA's future human exploration of space and such power systems must have advanced safety feature and provide high specific energy and high volumetric energy density. Luna Innovations propose to develop novel rechargeable battery with advanced non-toxic and safe anode and cathode materials. Aggressive weight and volume performance improvements over state-of-the-art lithium-ion batteries will be achieved for use in NASA's size-sensitive space vehicles. The proposed graphene nanocomposite-based cathode can be used in coupling with advanced silicon anodes that are much safer compared to lithium metal anodes used in conventional Li-ion batteries. The new battery technology incorporates novel graphene/nanosheet composite in the cathode design to provide higher efficiency for active material utilization and improved reversibility in the electrochemical reactions thus to provide higher energy density and greater cycling stability. We anticipate that the new rechargeable battery will meet all of the metric goals including safety, stability, cycle life and power that specified by NASA for its human-rated space applications.